Extensive Sorption of Organic Compounds to Black Carbon, Coal, and

Critical Review

Extensive Sorption of Organic Compounds to Black Carbon, Coal, and Kerogen in Sediments and Soils: Mechanisms and Consequences for Distribution, Bioaccumulation, and Biodegradation G E R A R D C O R N E L I S S E N , †,‡ O ¨ R J A N G U S T A F S S O N , * ,† THOMAS D. BUCHELI,§ MICHIEL T. O. JONKER,| ALBERT A. KOELMANS,⊥ AND PAUL C. M. VAN NOORT# Department of Applied Environmental Sciences (ITM), Stockholm University, 10691 Stockholm, Sweden, Department of Environmental Engineering, Norwegian Geotechnical Institute (NGI), P.O. Box 3930 Ullevål Stadium, N-0806 Oslo, Norway, Agroscope FAL Reckenholz, Swiss Federal Research Station for Agroecology and Agriculture (FAL), Zu ¨ rich, Switzerland, Institute for Risk Assessment Sciences (IRAS), Utrecht University, The Netherlands, Wageningen University and Research Centre (WUR), Wageningen, The Netherlands, and Institute of Inland Water Management and Wastewater Treatment (RIZA), Lelystad, The Netherlands

Evidence is accumulating that sorption of organic chemicals to soils and sediments can be described by “dual-mode sorption”: absorption in amorphous organic matter (AOM) and adsorption to carbonaceous materials such as black carbon (BC), coal, and kerogen, collectively termed “carbonaceous geosorbents” (CG). Median BC contents as a fraction of total organic carbon are 9% for sediments (number of sediments, n ≈ 300) and 4% for soils (n ) 90). Adsorption of organic compounds to CG is nonlinear and generally exceeds absorption in AOM by a factor of 10100. Sorption to CG is particularly extensive for organic compounds that can attain a more planar molecular configuration. The CG adsorption domain probably consists of surface sites and nanopores. In this review it is shown that nonlinear sorption to CG can completely dominate total sorption at low aqueous concentrations (100 33 3

122 118 130 121a 133 123 93 55 85 184 88 131 185 186 134 108 132 117 107

4-18 6-14

∼300f 19f

n.a.e 0.07-0.15d 1.7-4.9 n.a.e 3-13b 3-15 6-15 ∼10-30 n.a.e

1 5 23 2 38 9 7 4 1

2-13 2-12

90f 9f

108 118 106 93 102 140 131 141 107

a Partly unpublished data. b Values approximated from graphical data representation. c Higher values (median 8%) before extensive chemical pretreatment. d Higher values (median 5%) before extensive chemical pretreatment. e Not applicable. f Number of data on which median and quartile range are based. g Median where each soil/sediment sampling site has a weight of one. h Median where each reference has a weight of one.

developed by Griffin and Goldberg (138). Unfortunately, this method will detect both kerogen and BC. For shales containing OM that almost entirely consisted of kerogen, standard demineralization methods may suffice to isolate a kerogen-rich fraction (e.g., 6, 76). However, in neither of the above studies was it tested whether the isolated fraction indeed did consist of mainly kerogen. A criterion that might possibly be used to test for geochemical consistency is the 14C content of the isolates: as kerogen formation involves the slow process of metamorphosis (116), it probably will contain no 14C. Environmental Distribution and Contents: BC. As BC can be subjected to atmospheric transport, wet- and drydeposited BC can be found virtually everywhere (e.g., 106, 115, 117, 130). As follows from the above discussion, reported BC contents are partly dependent on the quantification method. For example, in a round-robin test (139) the chemical and lower-temperature (340 °C) thermal methods returned the highest BC contents, whereas optical methods and the high-temperature (375 °C) thermal method produced the lowest figures. Thermal-optical methods appeared to generate intermediate figures. The median value of around 300 literature BC:TOC ratios for sediments from many different locations around the world measures 9% (quartile range 5-18%; Table 2). For 90 soils, the median BC:TOC literature value is 4% (quartile range 2-13%; Table 2). However, in fire-impacted soils the content of charcoal BC may be exceedingly high, up to 30-45% of TOC (140, 141). Environmental Distribution and Contents: Coal and Kerogen. In contrast to BC, coal is not often encountered in 6884

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pristine soils and sediments because most unmined coal is deeply buried (115). Coal will be most abundant in major rivers and harbors near coal mining and shipping areas. Through petrographic analyses, Karapanagioti et al. (10, 156) found that the TOC of an aquifer soil contained 3% coal and 11% charcoal, and reported 0-14% charcoal in the TOC of 10 sediments. Using a petrographic approach, a coal + kerogen content of 1.6% on a total mass basis (approximately 15% of TOC) was found for a heavily contaminated sediment from a River Rhine sedimentation area (88). Kerogen is far more abundant than coal in the Earth’s crust (115). Although most kerogen is in deeply buried reservoirs (116, 142), it can still be present in significant amounts in soils and sediments. For example, Ran et al. (81, 143) found that Borden aquifer TOC (TOC content 0.02%) consisted of 18.7% kerogen. Song et al. (107) reported 2448% kerogen in one soil and three sediments. It has to be kept in mind, however, that no geochemical consistency testing was done to verify these results.

3. Extent and Mechanisms of Sorption to CG Sorption Parameters of CG. The Freundlich equation is most universally used for the description of sorption data. For a multiple-domain sorbent exhibiting both linear absorption and nonlinear adsorption, overall sorption can be described by

CS ) fAOCKAOCCW +

∑f K

nF,X X F,XCW

(1)

X

where CS is the sorbed concentration on a whole sediment

TABLE 3. Freundlich Sorption Parameters of Phenanthrene (PHE) in CG; All KF Data Have Been Converted to Units of [(µg/kgCarbon)/(µg/L)nF] ref

sample

CW/Sa

nb

Log KF

nF

nc

remark

BC 88, 111 four lacustrine sediments 10 isolated charcoal 14 pure charcoal 93 EPA soils and sediments 79 pure soots

10-7 to 10-2

4.6-5.4

10-2 to 1 10-5 to 1 10-3 to 1

5.5 5.6 5.6-6.4

n.m.d

5.6-6.4

10-4

10-0.5

4 0.54 1 0.57 1 0.58 12 0.56-0.79

opaque particles pure diesel soot charred kerogen

to 10-3 to 10-2 10-4 to 1

5.6-6.8 5.7 5.7; 5.9

79

pure charcoal

n.m.d

6.3

1 na

6.3-6.5

1 modeled

Boston Harbor 10-4 sediment median per measuremente median per referencef

1 1 12

5 na

11 94 82

93

4

10 na 1 1.00 2 0.30; 0.24

1 2

“Environmental” KF corrected for attenuation effect added PHE added PHE reinterpreted sorption data from (5), KAOC assumed for the calculations KBC at low concentrations (no isotherms), native PHE Probably both BC and coal nF ) 0.67 for pyrene Charred at 450 °C (77% BC) and 500 °C (80% BC), respectively KBC at low concentrations (no isotherms), native PHE reinterpreted sorption data from (27), KAOC (104.0), nF (0.6-0.8) assumed

5.9 (5.6-6.3)g 38h 0.61 (0.58-0.64) 21h 5.9 (5.6-6.1) 10h 0.58 (0.55-0.63) 6h Coal

13

coals

10-3 to 10-0.5 4.7; 5.1

14 80 11 10

pure coals pure coals opaque particles Canadian River alluvium sed. Pittsburgh coal pure coal

10-4 to 10-0.5 10-8 to 10-2 10-4 to 10-0.5 10-2 to 1

5.1; 5.2 5.4-6.0 5.6-6.8 6.3

10-4

6.5 6.6

15 79

to 1 n.m.d

median per measuremente median per referencef

2 0.78; 0.78 2 5 10 1

0.59; 0.79 0.66-0.79 na 0.55

1 0.56 1 na

5.8 (5.5-6.3) 6.2 (5.4-6.4)

2 2 5 1 1

coal particles present in soil and rock; added PAHs added PHE added PHE Probably both BC and coal coal isolated from sediment; added PHE added PHE KOC at low concentrations (no isotherms), native PHE

21h 0.74 (0.63-0.79) 11h 7h 0.69 (0.56-0.74) 5h

Kerogen and Shale 157 82 13 81 5, 76

Green River & Pula kerogen isolated Borden kerogen bituminous shale kerogen from Kunming, China shale kerogens

10-2

to

10-0.3

5.4; 5.4

2 0.76; 0.74

2

added PHE

5.8

1 0.69

1

10-4 to 10-0.5 5.8 5.8-6.4 10-4 to 1

1 0.74 5 0.39-0.65

1 5

10-3 to 1

3 0.39-0.58

3

added PHE; kerogen and thermally altered kerogens added PHE added PHE; isolated kerogen after 42 d equilibration added PHE; isolated kerogen from shales added PHE

10-3 to 1

15 Lachine shale 10-4 to 1 median per measuremente median per referencef

6.8-7.1 6.5 6.1 (5.8-6.5) 6.0 (5.8-6.4)

1 0.56 1 13h 0.61 (0.51-0.68) 13h 6h 0.63 (0.56-0.73) 6h

a Relative concentration range over which sorption isotherms were measured; S is solid PHE solubility. b Number of data on which K is based. F Number of data on which nF is based. d n.m., not explicitly mentioned in the reference, but in the order of CW/S of 10-6. e Median where each f g soil/sediment sampling site has a weight of one. Median where each reference has a weight of one. Median and quartile range (for all median values in this table). h Number of data on which median and quartile range are based. c

basis (µg/kg dry weight or dw), fAOC is the fraction of non-CG amorphous organic carbon (AOC), KAOC is the linear AOCwater partition coefficient, CW is the aqueous concentration (µg/L), fX denotes the fractions of the various CG moieties (BC, coal, kerogen), KF,X is the CG Freundlich sorption coefficient [(µg/kgX)/(µg/L)nF,X], and nF,X is the Freundlich nonlinearity coefficient of sorption to CG. Note that TOC ) AOC + CG. Sorption in AOC is presumed linear with nF,AOC ) 1, analogous to a dissolution process, whereas sorption to BC, coal, and kerogen can be highly nonlinear with nF,X as low as 0.3-0.7 (4-8, 10-16, 75, 81, 82, 86, 88, 89, 92-94, 97, 111, 144) (Table 3). Analogous to the former sorption paradigm (e.g., 2, 3), in eq 1 all of the AOM is considered homogeneous with respect to organic compound sorption properties. Extensive and nonlinear sorption to CG (exceeding sorption to AOM by 1-3 orders of magnitude) has been shown for a plethora of compounds, such as PAHs (10, 11, 13-15,

79, 81, 84, 88, 89, 94, 97, 111), polychlorinated biphenyls (PCBs (79, 89, 96)), PCDD/Fs (95), polybrominated diphenyl ethers (PBDEs (95)), the pesticide diuron (109, 110, 144), benzene and chlorobenzenes (14, 81, 86, 127), and chlorinated short-chain aliphatic compounds (4, 144). Although Langmuir isotherms are mechanistically more suitable to describe competition, and some efforts have been undertaken to describe adsorption onto BC in terms of Langmuir adsorption (100, 131, 145), we will describe sorption to CG in terms of the Freundlich model to facilitate comparisons with many earlier reports. Table 3 provides a literature overview of CG Freundlich sorption parameters for phenanthrene (PHE). PHE is a model organic compound that has been used frequently to explore the magnitude, mechanism, and consequences of extensive sorption of organic compounds to CG. Although PHE is only a moderately hydrophobic compound with a log KOW of 4.5 VOL. 39, NO. 18, 2005 / ENVIRONMENTAL SCIENCE & TECHNOLOGY

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(e.g., 12-14, 88, 89), its relatively extensive sorption to CG in relation to AOC is comparable to the behavior of many other more hydrophobic compounds (e.g., 79, 94-96, 145). We therefore assume that the explorations hereafter to be presented for PHE also apply to a broad array of planar compounds (see next paragraph). The most important criterion in the selection of data for Table 3 was that the equilibration of the solid-water systems was sufficient, i.e., at least in the order of one month. Especially for larger CG particles (>10-100 µm), required equilibration times may be long (6, 10, 15, 111). In case of insufficient equilibration, actual K-values may be higher than reported in Table 3. The median values in Table 3 suggest that BC, coal, and kerogen exhibit similar C-normalized sorption coefficients for PHE (median log KF between 5.8 and 6.2) and similar isotherm nonlinearities (median nF between 0.58 and 0.74). The KF and the nF quartile ranges overlapped and averaged values of KF and nF did not significantly vary among the three types of CG (t-test, 95% confidence level). Variation in KF and nF is probably caused by variations in CG quality and/or differences in experimental approaches. KF increases and nF decreases with increasing C/O, C/H, and C/N ratios as well as with increasing CG aromaticity (4-8, 75, 80, 82). An increasing specific surface area will probably cause an increase in KF (94). Planarity Effects. The planarity of sorbate molecules seems to play an important role in sorption to CG since (i) BC sorption coefficients of non-ortho substituted, planar PCBs are up to 1 order of magnitude higher than those of ortho-substituted, nonplanar ones of similar KOW (79, 89, 96), (ii) KTOC values are higher for planar compounds than for nonplanar ones with similar KOW in the case of aerosols (146) and contaminated freshwater sediments (35, 37), (iii) PCDFs have both higher laboratory-derived KBC values (95) and elevated field-observed KTOC values (85), and correlated better with BC contents than TOC levels, as compared to PCDDs with similar KOW (85). This is consistent with a difference in the energy-minimized torsional angle: ab initio molecular modeling suggests that this angle is significantly less than 180 °C for PCDDs, but not for PCDFs (95). Thus, it is probably less thermodynamically favorable to attain a planar configuration for PCDDs upon sorption to CG than it is for PCDFs. Recent modeling work has confirmed that sorbate planarity has an important effect on sorption affinities (145) and capacities (100). The sorption of nonplanar atrazine to two CG materials (coal humic acid (147) and isolated environmental BC, i.e., BC as present in natural environments (144)) was of magnitude similar to that of absorption into AOM. On the other hand, nonplanar diuron did show elevated sorption to CG compared to AOC (109, 110, 144). Molecular modeling revealed that this difference could not be easily explained in terms of polarizability, dipole moments, and/or planarity (144). However, the elevated sorption to CG by diuron does imply that a rigid, completely planar structure is not a prerequisite for extensive sorption to CG. It seems rather that the configurational ability to attain (near)-planarity is of importance. Mechanism of Sorption to CG. Generally, the magnitude of the interaction between a hydrophobic sorbate and a CG is affected by dispersive interactions between sorbate and sorbent electron systems. The strength of these interactions depends on the sorbate/sorbent separation distance (steric effects) (148). It has been hypothesized that the mechanism of sorption to CG involves (partial) phase transition energies, whereby CG-sorbed organic compounds attain a semisolid state (87) or a translationally restricted two-dimensional state (145). The close planar association restricts sorbate translational energies in one out of three dimensions, and rotational energies in two out of three dimensions (87, 145). 6886

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The considerable enthalpic and entropic effects of this partial phase transition may be one of the causes for the extensive sorption to CG. Two observations indicate that proton or electron donor/ acceptor interactions also may play a role in sorption to carbonaceous geosorbents: Nitrobenzene sorption to an artificial char exceeded benzene sorption (112), and sorption of the π-electron donor compounds pentamethylbenzene, naphthalene, and phenanthrene to CG-containing soil increased with decreasing pH, whereas there was no pHeffect for the non-π-donor compounds trans-1,2-dichlorocyclohexane, hexachloro-1,3-butadiene, 1,2,4-trichlorobenzene, 2,2′,5,5′-tetrachlorobiphenyl, and 3,3′,4,4′-tetrachlorobiphenyl (149). Two types of CG sorption sites have been proposed in the literature: (i) sorption on a relatively rigid, planar, aromatic surface, and (ii) sorption in narrow nanopores inside the sorbent. There is not necessarily a distinction between these (e.g., sorption to nanopore surfaces). In addition, the observations for “native” PAHs of extremely slow desorption (half-lives of years to centuries (101)) and difficult to extract PAHs (91) from CG indicate the potential existence of very inaccessible nanopore sites, so-called “occlusion sites” (27, 30, 58, 79). Observations that point to the presence of surface sorption sites include (i) sorption coefficients of several CG materials being remarkably constant on a surface-area basis (94), (ii) observed CG maximum sorption capacities corresponding fairly well with monolayer surface coverage (111), and (iii) microscopic observations indicating that PAHs mainly reside in the external surface regions of CG (83). Observations that suggest the existence of CG-sorbed solutes residing in (nano)pores include (i) a close agreement between the volume of sorbed PAHs and the micro- and mesopore volume for a variety of coals and charcoal (14), (ii) benzene causing swelling of charcoal nanopores, which implies that these pores do not possess a rigid structure (86), and (iii) maximum PHE sorption capacities of coal (80) exceeding those of BC (111), whereas coal specific surface areas are much lower than those of BC (Table 1 and ref 80). With respect to the latter argument, it should be remarked that coal surface areas based on CO2 adsorption at 273 K are much higher (100-200 m2/g (151), in the same order of magnitude as BC) than the ones based on N2 adsorption at 77 K (1.5-4.6 m2/g, Table 1). This might also explain that sorption coefficients are so similar for coal and BC despite their disparate N2-based surface areas. Observations that can be reconciled with both surface and nanopore sorption include (i) specific pore-swelling/ PAH displacing solvent mixtures are needed to extract PAHs from CG (91), and (ii) strong correlations of CG-water and CG-gas distribution coefficients with the average CG pore volumes (79, 150), as pore volumes are probably correlated with surface areas. The aforementioned planarity effects can be explained by sorption to both types of CG adsorption sites. First, a larger separation distance between CG surface sites and a nonplanar sorbate probably weakens the dispersive electronic interactions with a flat, aromatic surface. Second, nonplanar compounds may be too “thick” to fit into the majority of CG nanopores and occlusion sites, whereas the thickness of planar compounds is below the average nanopore size (79, 100). The average interlayer spacing in a diesel soot, i.e., the distance from the center planes of two parallel π systems (4.1 Å, as observed by transmission electron spectroscopy (114)) and the nanopore width in an environmental BC isolate (4-10 Å range (89)) have been observed to be of order of magnitude similar to that of the molecular thicknesses of many organic compounds (152).

FIGURE 2. Importance of CG to total PHE sorption in an imaginary sediment where CG is 10% of TOC. Log KAOC was assumed to be 4.5; for log KF,CG and nF,CG the median values for BC, coal, and kerogen were taken (6.0 and 0.64, respectively; Table 1 and text). The situation is sketched with and without CG attenuation due to native compounds and/or OM (see text). In summary, different types of CG sorption sites have been proposed, but the exact mechanism of sorption to CG has not yet been unraveled.

4. Sorption to CG: Implications for Organic Compound Distribution in the Environment Importance of CG to Total Sorption. PHE sorption coefficients for AOC are generally in the order of 104.0-5.0 (e.g., 5, 6, 12, 88). As KF,CG measures about 106.0 at 1 µg/L (Table 3), this means that PHE sorption to pure CG exceeds sorption in AOC by a factor of 10-100 at aqueous concentrations of 1 µg/L. As a result of sorption nonlinearity, sorption coefficients of pure CG are, however, approximately one log unit higher at 1 ng/L than at 1 µg/L. Therefore, sorption to pure CG exceeds sorption in AOC 100-1000 times at these low concentrations (79, 80, 111). As stated earlier, the abovementioned observations can perhaps be generalized to other PAHs, planar PCBs, PCDD/Fs, and PBDEs. However, it was shown that PHE sorption to environmental BC (i.e., BC as present in natural environments) can be as much as 1 order of magnitude lower than sorption to pure BC (111, 153). This attenuation effect is caused by native organic compounds and/or AOM molecules competing for or blocking CG sorption sites (92, 153). The latter mechanism is analogous to the well-documented phenomenon of activated carbon fouling by humic substances (e.g., 154, 155). Attenuation of sorption has only been shown for BC (92, 153) and coal (153). However, it can be expected to occur for kerogen as well, because for this material (i) sorption has also been observed to be nonlinear (6, 15, 76, 81, 82, 157), and (ii) competitive sorption has been shown (77, 158, 159). In Figure 2, the importance of CG to total PHE sorption is sketched for an imaginary sediment with a realistic CG/TOC ratio of 10% (Table 2). Curves are shown for cases excluding and including the attenuation effect. Because of the similarity in sorption parameters for different types of CG, generic values for KF,CG and nF,CG of 106.0 and 0.64 (Table 3), respectively, were used in this figure. These generic values are thus based on a large literature data set (n ≈ 100). These values will also be applied in forthcoming modeling calculations exploring the effect of sorption to CG on environmental distribution, bioaccumulation, and bioremediation potential. The attenuation effect was quantified on the basis of sorption isotherms over a wide concentration range before and after combustion at 375 °C (111) and on the basis of PCB sorption to coal and charcoal in the presence and absence of sediment (153). The magnitude of the attenuation effect appeared to be variable, but generally was around 1 order of magnitude. Hence, in Figures 2-5 it will be assumed that sorption to CG in the environmental situation is 1 order of magnitude weaker

FIGURE 3. Predicted log KTOC of PHE vs the CG/TOC ratio (%), on the basis of the median sorption parameters of CG (Table 3) at 1 µg/L and 1 ng/L. “Attenuation” indicates whether the effect of CG sorption attenuation (assumed to be 1 order of magnitude) due to competition with native compounds and/or OM is taken into account. than sorption to pure CG due to competition with native compounds and/or OM. It should be stressed, though, that it remains uncertain whether this attenuation factor can be extrapolated to other soils and sediments. In the absence of sorptive attenuation, total sorption is dominated by sorption to CG up to concentrations of 1 µg/L (CW/S ≈ 10-3, where S is the maximum solid solubility; Figure 2). In the environmentally more realistic situation where the attenuation effect does occur, sorption to CG overwhelms sorption in AOC up to approximately 10-100 ng/L (CW/S ≈ 10-5; Figure 2). At approximately 200 ng/L, CG and AOC are equally important for total PHE sorption when attenuation is taken into account. As various planar compounds compete for a limited number of CG sorption sites (14, 35, 92, 94, 111), the solubility-normalized concentration on the x-axis in Figure 2 should be regarded as the sum of solubilitynormalized concentrations of planar compounds that compete with PHE for CG sites. The total concentration of compounds that can attain a planar configuration probably consists of both “contaminants” (mainly PAHs) and natural (probably partly planar) biomolecules. With respect to the latter, it has been shown that natural aromatic acids can compete for sorption sites with chlorobenzenes and chlorophenols (158). Elevated OC-Water Distribution Coefficients in the Field. Numerous examples of TOC-water distribution coefficients well above those predicted from equilibrium partitioning into AOC (i.e., KTOC > KAOC) have been reported for many different aquatic environments and several different compound classes (reviewed in e.g., 29, 30, 87). For instance, Socha and Carpenter (38) found that the sorption of pyrogenic (“soot”) PAHs exceeded that expected on the base of AOC equilibrium partitioning. McGroddy and Farrington (27) defined a fraction of field-PAHs that was not “available for equilibrium partitioning (AEP)”. This fraction amounted up to 95-99% for a range of PAHs in Boston Harbor sediments. Later on, BC contents were determined for these samples, and it was concluded that extensive sorption to BC could well explain the observed elevated KTOC values (30, 93). There is a large body of similar evidence for elevated solid-water distribution coefficients in the field that were probably due to the presence of CG as well (e.g., 28, 32, 35, 36, 39, 88, 160, 161). Using the median sorption parameters of CG from Table 3, it can be estimated how sorption to CG will influence the apparent KTOC for PHE (see Figure 3). From Figure 3, it appears that sorption to CG can explain a 1-2 orders of magnitude increase in KTOC, and that this increase is dependent on the total (planar) sorbate concentration, as discussed in the previous section. At lower concentrations, the elevation in KTOC is more pronounced. Figure 3 also demonstrates that at sites where CG contents are in the order of a few percent of TOC (106, 120), the KTOC enhancement will generally be VOL. 39, NO. 18, 2005 / ENVIRONMENTAL SCIENCE & TECHNOLOGY

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less than one log unit, even at low sorbate concentrations (no saturation of CG sorption sites). In CG-rich soils and sediments, however, the increase in KTOC may be strong, although the presence of high CG levels is often accompanied by high native sorbate levels that can diminish the sorbent abilities of CG by competitive effects. CG as a Descriptor of Environmental Organic Compound Distribution. If sorption to a sediment or soil is dominated by sorption to CG, a positive correlation between the spatial distributions of CG and contaminant concentrations can be expected for chemicals that have the same source as the CG (e.g., pyrogenic PAHs and PCDD/Fs). Likewise, AOC-dominated sorption should be accompanied by positive correlations between TOC and sorbate contents. Several studies have shown thus far that the environmental distribution of PAHs correlates better with CG contents than with TOC levels in both lake sediment cores (30, 132) and in marine surface sediments (87). The same was found for PCDD/Fs in marine suspended particulate matter and surface sediments (85). Inclusion of CG (specifically, BC) in a soil-air partitioning model improved the prediction of PAH concentrations for samples with high CG/TOC ratios, whereas it led to overprediction of PAH contents at low CG/TOC ratios (102). In addition, the particle fraction containing the CG, invariably a minor fraction on a mass basis, was observed to contain the majority of sorbed organic compounds (34, 72, 83, 162). All these results indicate CG-dominated sorption in many systems. The absence of a relationship between levels of CG (specifically, BC) and low-molecular-weight PAH contents in 23 Swiss soils containing only background contamination of organic contaminants (106) was explained by heterogeneity of BC among different sites and the low BC/TOC ratios (1-6%). Rockne et al. (162) did not observe a correlation between CG and PAH contents in a sediment either, which might point to either (i) an additional (i.e., petrogenic) source of the chemicals or (ii) saturation of the CG sites making AOM absorption the dominant sorption mechanism (Figure 2). The increase in overall sorption strength due to CG has important consequences for desorption kinetics, bioaccumulation, and biodegradation. These consequences will be discussed in the forthcoming sections.

5. Sorption to CG: Implications for Desorption Kinetics Part of the soil/sediment-sorbed organic compounds is released slowly into water over time scales of weeks to years (e.g., 17, 19, 24-26, 73, 162). This process has been termed slow, resistant, rate-limiting, or nonequilibrium sorption. As early as 1996 it was hypothesized by Pignatello and Xing that slow diffusion in, or extensive sorption to, rigid parts of the OM matrix could be responsible for this slow desorption (17). In addition, these authors proposed that the slowly desorbing fraction was proportional to the extent of enhanced sorption. So, if, e.g., 90% of the sorbate would desorb slowly, one might expect the equilibrium KTOC to be a factor of 10 higher than anticipated on the basis of equilibrium partitioning into AOC only. Later, this relationship was confirmed by experimental observations (e.g., 21, 163). As CGs are held responsible for high KTOC-values, they therefore probably cause slow desorption as well. This has in fact been suggested before (e.g., 53, 79, 152). Therefore, it is hypothesized that the “rigid”, “glassy” OM domain originally proposed by the groups of Weber (5-8, 76) and Pignatello (17, 158, 159, 164) is in fact the same as the CG domain, and thus that sorption to CG probably causes slow desorption. Experimental observations that support this hypothesis include (i) the majority of CG-bound PAHs was observed to desorb over a time scale of decades to centuries (101), (ii) slowly desorbing sorbate fractions demonstrated nonlinear sorption (18), (iii) native planar compounds desorbed more slowly than non6888

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planar ones (152), consistent with planarity effects on sorption to CG (Section 3), and (iv) reported maximum sorption capacities (Qmax) are in the same order of magnitude for the “glassy” adsorption domain (5, 12, 22, 86), the CG domain (80, 93, 100, 111, 127), and the slow sorption domain (18, 131): all these domains appear to have capacities in the range of 0.2-3 mg/g C (131). The above hypothesis is mechanistically feasible, regardless of the character of the CG adsorption sites (occlusion sites, nanopores, internal/external surface sites). In all cases, either geometric factors (constrictivity, tortuous diffusion paths) and/or the high activation energy needed to overcome the described partial phase transition and the strong dispersive interactions between CG and sorbate will result in kinetically restricted release from the sites and/or slow intraparticle diffusion. There are no explicit thermodynamic data for CG to substantiate the hypothesis of a high activation energy, although the activation enthalpies of slow desorption of PAHs and PCBs from whole sediments were high (60-100 kJ/mol (e.g., 19)). If the “glassy” domain, the “slow desorption” domain, and CG truly are the same geosorbent component, the CGbound fractions in Figure 2 also represent the slowly desorbing PHE fractions as a function of CW at a CG/TOC ratio of 10%. The described attenuation effect probably reduces slowly desorbing fractions as well, as indicated by the observations of competition and limited capacities for the slow sorption domain (18, 20).

6. Sorption to CG: Implications for Bioaccumulation At constant solid-water ratios, sorption to CG decreases porewater concentrations (CW; Figure 3). Because uptake of organic chemicals is assumed to proceed mainly via the aqueous phase, sorption to CG will therefore reduce concentrations of these compounds in aquatic organisms. Thus, with variation in geosorbent quality (e.g., CG and AOC contents), the biological uptake of organic compounds can be expected to vary. In the present section we will formulate a CG-inclusive framework to describe such variations in bioaccumulation. Bioaccumulation is usually expressed in terms of the biotato-sediment-accumulation-factor (BSAF), the ratio of the concentrations of a given organic compound in the lipids of a sediment/soil-dwelling organism to the concentrations in the sorbent TOC (e.g., 46, 48, 165)

BSAF )

Clipid KlipidCW ) CTOC CS/fTOC

(2)

in which Clipid is the lipid-normalized sorbate concentration in the organism (µg/g lipid), CTOC is the TOC-normalized sorbate concentration in the geosorbent (µg/g TOC), CS is the total sorbate concentration on a dry weight basis (µg/g dw), fTOC is the TOC fraction, and Klipid (L/kg) is the lipidwater partition coefficient. Note that eq 2 reflects the situation in which equilibrium exists between biota lipids and geosorbent, irrespective of the uptake route. Evaluating the influence of CG on the BSAF is visualized by substituting eq 2 into eq 1 and rearranging (165)

Klipid

BSAF ) KAOC +

∑f X

fX

(3)

KF,XCnWF,X-1

TOC

where we set fAOC ) fTOC, a valid approximation for our current purposes because CG usually constitutes around 10% of TOC (Table 2). We recognize that also Klipid is not necessarily constant for all organisms (e.g., 51, 55, 166), but it is outside

FIGURE 4. Predicted BSAF of PHE in a hypothetical organism with a given lipid composition such that Klipid ) KOW vs the CG/TOC ratio (%), on the basis of the median sorption parameters of CG (Table 3) at 1 µg/L, 1 ng/L, and 1 pg/L. “Attenuation” indicates whether the effect of CG sorption attenuation (assumed to be 1 order of magnitude) due to competition with native compounds and/or OM is taken into account. the scope of the present review to take into account this relatively small variation as well. The graphical presentation of eq 3 is shown in Figure 4. This figure demonstrates that sorption to CG can explain a 1-2 orders of magnitude lower BSAF value at environmentally relevant PHE concentrations of 1 ng/L (CW/S ) 10-6). At yet lower CW, the influence of CG will increase even further, whereas at higher CW it will be less. Equation 3 and Figure 4 also demonstrate that the nonlinearity of sorption to CG can render BSAF values concentration-dependent for a given combination of geosorbent, organism, and compound. Hence, it is of paramount importance to perform bioaccumulation and toxicity tests at the relevant environmental concentration (165). An example of the concentration dependence of PAH uptake is illustrated in a study by Gerde et al. (90), who observed that at low concentrations (far below Qmax), aerosol-bound benzo[a]pyrene was not taken up by dogs, whereas it was at higher concentrations. Explicit evidence of the influence of CG on BSAF includes (i) BSAFs of sediment amended with BC-bound pyrogenic PAHs were six times lower than those of the same sediment amended with petrogenic PAHs (52), as the sediment containing pyrogenic PAHs showed a higher BC content and thus stronger sorption, (ii) the addition of coal and charcoal led to an extensive reduction of concentrations of sedimentbound PCBs in aquatic worms (153), and (iii) uptake of benzo[a]pyrene (BaP) by clams was lower from coke, char, anthracite, and activated carbon than from wood and diatoms (59). In the latter two studies, BSAFs were lower for planar compounds than for nonplanar ones of similar KOW, obviously because sorption to CG is most extensive for compounds that can attain a planar configuration. Thus, the oftenobserved difference in field-based BSAF between (planar) PAHs and (mainly nonplanar) PCBs (e.g., 60) can probably be explained by sorption to CG as well (49, 55, 153, 165). In addition, the generally higher toxicity of planar PCBs as compared to nonplanar ones could be partly offset by their lower BSAFs. There are many other studies in which sorption to CG has been invoked to explain variations in BSAF (29), e.g., variation in BSAFs of organic compounds for deposit-feeders in New York Harbor sediments (53), concentration dependence of BSAF for PCDD and PCDF in Dungeness crab (48), BSAFs for mussels being lower for pyrogenic PAHs than for petrogenic ones (47, 58), improved BSAF data modeling for PAH uptake in invertebrates through the inclusion of BC (55), and KTOC values being higher (31) and BSAFs being lower (56) in the rainy season than in the dry one due to higher surface runoff of BC.

FIGURE 5. Predicted readily biodegradable fraction of PHE vs the CG/TOC ratio, on the basis of the median sorption parameters of CG (Table 3) at 1 µg/L and 1 ng/L. “Attenuation” indicates whether the effect of CG sorption attenuation (assumed to be 1 order of magnitude) due to competition with native compounds and/or OM is taken into account. Field support for the consequences of sorption to CG for bioaccumulation was provided by the observation that BSAF values of native PAHs in six sediments decreased by approximately a factor of 20 when native BC contents increased from 0.1 to 0.45% (BC/TOC ratios were 4-13%) (49). This dependence is even slightly stronger than what would be expected on the basis of eq 3 (165). Obviously, the potentially profound effect that CG has on bioaccumulation has important implications for determining the optimal manner to carry out ecotoxicological risk assessments (Section 8).

7. Sorption to CG: Implications for Biodegradation Sorption to CG not only reduces desorption and bioaccumulation, it also limits biodegradation rates. Evidence for the link among these three processes was mainly provided by the group of Alexander (e.g., 42-44, 74). The prevailing hypothesis is that extensive sorption to CG leads to slow desorption of a part of the sorbed organic compounds. The slowly desorbing fraction is only biodegradable on very long time scales (e.g., 42-44, 73, 74). This was supported by the findings of (i) a 1:1 relationship between slowly desorbing fractions and fractions that could not be remediated within years in the absence of any microbiological limitations (61), (ii) a relationship between fractions extracted by SFE and both bioremediated (69, 70) and XAD-2/water extracted (68, 70) fractions, indicating that the fraction that could not be extracted by water (i.e., the CG-bound fraction) is the fraction that cannot be bioremediated within reasonable time spans (i.e., years), (iii) semisolid tar-pitch-associated PAHs being rapidly degradable, in contrast to CG-associated ones (72, 83), and (iv) complete absence of naphthalene biodegradation in soils and sediments due to granular activated carbon that physicochemically resembles CG (71). Currently, it remains unclear whether the CG-sorbed and slowly desorbing fractions cannot be degraded at all, or are degraded over long time spans (>years). Once the easily available organic compounds absorbed in AOM have become exhausted, porewater levels may drop below threshold concentrations required by the microbes. Therefore, degradation might stop after the AOM-bound fraction has been degraded. However, many organic compounds are cometabolized and in those cases no threshold is expected. Therefore it seems likely that the CG-bound organic compounds are degradable, but only after prolonged times. In Figure 5, the hypothesis of CG-sorbed organic compounds being unavailable for biodegradation is illustrated by sketching the relationship between CG/TOC ratio and potential biodegradability within years of PHE in soil/ sediment. This figure shows that sorption to CG can explain limited biodegradation in the absence of microbiological VOL. 39, NO. 18, 2005 / ENVIRONMENTAL SCIENCE & TECHNOLOGY

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limitations. As the fraction of CG increases, the rapidly biodegradable fraction of PHE diminishes. The biodegradable fractions also decrease with decreasing CW, e.g., at 1 ng/L the potential rapid biodegradability is much less than that at 1 µg/L (Figure 5). This implies that sediments and soils with the highest contamination levels provide the best opportunities for bioremediation in the case where biodegradability is expressed as a percentage of the total sorbate content. The amount of nondegradable or slowly degradable organic compounds, often called the bioremediation “endpoint”, will probably be dependent on the total CG content. The endpoint will likely be close to the Qmax of the CG (0.2-3 mg/g C, see previous section). In conclusion, sorption of organic compounds to CG can explain limitations in both bioaccumulation and biodegradation.

8. Improved Basis for Legislation Ecotoxicological Soil/Sediment Quality Criteria. In most countries, existing soil and sediment quality criteria for organic compounds are based on total solid-phase concentrations. However, numerous studies have now demonstrated that these total contents bear little or no relation to actual concentrations in organisms. The current review provides a basis for understanding this discrepancy: BSAFs will vary due to sorption to CG (Figure 4). The setting of quality criteria or “benchmarking” is based on toxicological experiments carried out in aqueous systems. On the basis of compound-specific “no observed effect concentrations” (NOECs), aquatic quality criteria (µg/L) have been derived. Most of these criteria were derived during the early 1990s, when it was difficult to adequately quantify freely dissolved aqueous concentrations. Therefore, aqueous quality criteria were converted into sediment/soil quality criteria (mg/kg), using generic KTOC values. These KTOC-values were based on equilibrium partitioning with AOC as the sole sorbent domain. However, the ubiquitous presence of CG in sediments and soils renders these generic KTOC values more or less useless, because CG can cause a variation in real-world KTOC values of several orders of magnitude (Figure 3). Because of the unsuitability of total concentrations for ecotoxicological risk assessment, the existing sediment/soil quality criteria should be reconsidered. Future strategies could be based on actual risks. As freely dissolved concentrations are believed to reflect such risks, risk assessments could, for instance, be performed by comparing measured freely dissolved concentrations to the originally derived aqueous quality criteria. Nowadays freely dissolved concentrations can be determined easily using state-of-the-art methods, such as solid-phase extractions using solid-phase micro-extraction (SPME) fibers (40, 167, 168), polyoxymethylene (84), or low-density polyethylene (36, 37, 39), where the freely dissolved concentrations are inferred from the uptake in these polymers. In contrast to total soil/ sediment contents, freely dissolved concentrations are related to concentrations in organisms (40, 168, 169), and thus provide a promising way to restore the relation between quality criteria and biological uptake. This agrees with a recent National Research Council report (33, 170) and an Environmental Science and Technology A-pages article (169) in which it is concluded that: (i) the specific mechanisms of sorption of solid-bound contaminants should be understood, (ii) solid-phase extractions should be used to quantify bioavailable contents, and (iii) the measurements should be verified with biological surveys (bioassays, field inventories). Bioremediation Endpoints. The acceptability of bioremediation endpoints is usually judged on the basis of total solid-sorbed concentrations. However, sorbate fractions that are not degraded by microbes usually are not available for 6890

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uptake in higher organisms (e.g., 42, 74), provided that sorption to CG and not microbial limitations are the cause of the residual fractions. This implies that acceptance criteria could also be based on available (freely dissolved) concentrations instead of total ones. In this way, limited remediation funds can be better prioritized and useless remediation attempts of CG-bound organic contamination will be avoided.

9. Implications and Research Needs The implications of the CG-inclusive dual-mode sorption paradigm are far-reaching. Sorption to CG can explain the frequently observed enhanced field-KTOC values and BSAF decreases of 1-2 orders of magnitude (Figures 3 and 4) as well as biodegradational limitations up to 90-99% (Figure 5). However, many issues remain unresolved and at least the following need further research. (i) All existing BC quantification methods suffer from operational shortcomings, such as potential for charring, partial oxidation of BC, loss of small BC particles, and incomplete AOC removal. (ii) Up until now, research on the relation between sorption to CG and biological processes has mainly focused on uptake by benthic organisms and much less on microbiology and bioremediation. More insight should be gained into the relation between the presence and sorption characteristics of CG and the bioremediation potential of contaminated soils and sediments. Such insights could be used to predict the potential feasibility of a proposed remediation. (iii) Molecular planarity has been observed to affect sorption to most CG moieties, and extensive sorption to CG occurs for PAHs, planar PCBs, chlorobenzenes, PCDD/Fs, and PBDEs. However, information regarding the extent to which sorption to CG affects the fate and bioaccumulation of other compound classes remains limited to a few studies with chlorinated aliphatics (3, 144) and a couple of pesticides (109, 110, 144). (iv) To date, the exact nature of the CG adsorption sites remains unclear. Many observations can be reconciled with both surface and nanopore adsorption as well as with occlusion. Elucidation of the precise character of the sorption sites will increase knowledge on optimal remediation and risk abatement strategies and will aid in modeling adsorption in order to quantitatively estimate adsorption by various compounds. Unraveling the character of CG sorption sites will also help to understand the extent to which OM and native compounds show sorptive competition with organic compounds. Such information will aid in the correct quantification of the sorptive attenuation effect. (v) A potential but hitherto less explored manner to address some mechanistic questions is to study the thermodynamics of sorption to CG. Furthermore, spectroscopic techniques such as solid-state nuclear magnetic resonance spectroscopy could be employed to increase mechanistic understanding. Finally, valuable lessons may be learned from both physicochemical studies on sorption onto carbon surfaces (e.g., 171) and the wealth of data on sorption to activated carbon.

Acknowledgments This study was funded by the European Union (project ABACUS, contract EVK1-2001-00094). O ¨ .G. also acknowledges a Senior Researcher Fellowship from the Swedish Research Council (629-2002-2309). Amy M.P. Oen (Norwegian Geotechnical Institute) is thanked for her final linguistic check of the manuscript. Two anonymous reviewers are thanked for their constructive comments and suggestions.

Literature Cited (1) Lambert, S. M. Omega, a useful index of soil sorption equilibria. J. Agric. Food Chem. 1968, 16, 340. (2) Karickhoff, S. W. Sorption kinetics of HOCs in natural sediments. In Contaminants and Sediments; Baker, R. A., Ed.; Ann Arbor Press: Ann Arbor, MI, 1980; Vol. 2, p 193. (3) Chiou, C. T.; Peters, L. J.; Freed, V. H. A physical concept of soil-water equilibria for nonionic compounds. Science 1979, 206, 831. (4) Grathwohl, P. Influence of organic matter from soils and sediments from various origins on the sorption of some chlorinated aliphatic hydrocarbons: implications on Koc correlations. Environ. Sci. Technol. 1990, 24, 1687. (5) Huang, W.; Young, T. M.; Schlautman, M. A.; Yu, H.; Weber, W. J., Jr. A Distributed Reactivity Model for Sorption by Soils and Sediments. 9. General Isotherm Nonlinearity and Applicability of the Dual Reactive Domain Model. Environ. Sci. Technol. 1997, 31, 1703. (6) Huang, W.; Weber, W. J., Jr. A Distributed Reactivity Model for Sorption by Soils and Sediments. 11. Slow ConcentrationDependent Sorption Rates. Environ. Sci. Technol. 1998, 32, 3549. (7) Young, T. M.; Weber, W. J., Jr. A distributed reactivity model for sorption by soils and sediments. 3. Effects of diagenetic processes on sorption energetics. Environ. Sci. Technol. 1995, 29, 92. (8) Weber, W. J., Jr.; Young, T. M. A Distributed Reactivity Model for Sorption by Soils and Sediments. 6. Mechanistic Implications of Desorption under Supercritical Fluid Conditions. Environ. Sci. Technol. 1997, 31, 1686. (9) Chiou, C. T.; Kile, D. E. Deviations from Sorption Linearity on Soils of Polar and Nonpolar Organic Compounds at Low Relative Concentrations. Environ. Sci. Technol. 1998, 32, 338. (10) Karapanagioti, H. K.; Kleineidam, S.; Sabatini, D. A.; Grathwohl, P.; Ligouis, B. Impacts of Heterogeneous Organic Matter on Phenanthrene Sorption: Equilibrium and Kinetic Studies with Aquifer Material. Environ. Sci. Technol. 2000, 34, 406. (11) Karapanagioti, H. K.; Childs, J.; Sabatini, D. A. Impacts of Heterogeneous Organic Matter on Phenanthrene Sorption: Different Soil and Sediment Samples. Environ. Sci. Technol. 2001, 35, 4684. (12) Xia, G.; Ball, W. P. Adsorption-Partitioning Uptake of Nine LowPolarity Organic Chemicals on a Natural Sorbent. Environ. Sci. Technol. 1999, 33, 262. (13) Kleineidam, S.; Rugner, H.; Ligouis, B.; Grathwohl, P. Organic Matter Facies and Equilibrium Sorption of Phenanthrene. Environ. Sci. Technol. 1999, 33, 1637. (14) Kleineidam, S.; Schu ¨ th, C.; Grathwohl, P. Solubility-Normalized Combined Adsorption-Partitioning Sorption Isotherms for Organic Pollutants. Environ. Sci. Technol. 2002, 36, 4689. (15) Johnson, M. D.; Huang, W.; Weber, W. J., Jr. A Distributed Reactivity Model for Sorption by Soils and Sediments. 13. Simulated Diagenesis of Natural Sediment Organic Matter and Its Impact on Sorption/Desorption Equilibria. Environ. Sci. Technol. 2001, 35, 1680. (16) Allen-King, R. M.; Grathwohl, P.; Ball, W. P. New modeling paradigms for the sorption of hydrophobic organic chemicals to heterogeneous carbonaceous matter in soils, sediments and rocks. Adv. Wat. Res. 2002, 25, 985. (17) Pignatello, J. J.; Xing, B. Mechanisms of Slow Sorption of Organic Chemicals to Natural Particles. Environ. Sci. Technol. 1996, 30, 1. (18) Cornelissen, G.; Rigterink, H.; Van Noort, P. C. M.; Govers, H. A. J. Slowly and very slowly desorbing organic compounds in sediments show nonlinear Langmuir-type sorption. Environ. Toxicol. Chem. 2000, 19, 1532. (19) Cornelissen, G.; Van Noort, P. C. M.; Parsons, J. R.; Govers, H. A. J. The temperature dependence of slow adsorption and desorption kinetics of organic compounds in sediments. Environ. Sci. Technol. 1997, 31, 454. (20) Cornelissen, G.; Van der Pal, M.; Van Noort, P. C. M.; Govers, H. A. J. Competition effects in the slow desorption of organic compounds from sediments. Chemosphere 1999, 39, 1971. (21) Ten Hulscher, Th. E. M.; Vrind, B. A.; Van den Heuvel, H.; Van der Velde, L. E.; Van Noort, P. C. M.; Beurskens, J. E. M.; Govers, H. A. J. Triphasic Desorption of Highly Resistant Chlorobenzenes, Polychlorinated Biphenyls, and Polycyclic Aromatic Hydrocarbons in Field Contaminated Sediment. Environ. Sci. Technol. 1999, 33, 126. (22) Kan, A. T.; Fu, G.; Hunter, M. A.; Chen, W.; Ward, C. H.; Tomson, M. B. Irreversible Sorption of Neutral Hydrocarbons to Sediments: Experimental Observations and Model Predictions. Environ. Sci. Technol. 1998, 32, 892.

(23) Karickhoff, S. W.; Morris, K. R. Sorption dynamics of hydrophobic pollutants in sediment suspensions. Environ. Toxicol. Chem. 1985, 4, 469. (24) Brusseau, M. L.; Rao, P. S. C. Sorption Nonideality During Organic Contaminant Transport in Porous Media. CRC Crit. Rev. Environ. Control 1989, 19, 33. (25) Brusseau, M. L.; Jessup, R. E.; Rao, P. S. C. Nonequilibrium Sorption of Organic Chemicals: Elucidation of Rate-Limiting Processes. Environ. Sci. Technol. 1991, 25, 134. (26) Kan, A. T.; Fu, G.; Tomson, M. B. Adsorption-desorption hysteresis in organic pollutant and soil-sediment interaction. Environ. Sci. Technol. 1994, 28, 859. (27) McGroddy, S. E.; Farrington, J. W. Sediment Porewater Partitioning of Polycyclic Aromatic Hydrocarbons in Three Cores from Boston Harbor, Massachusetts. Environ. Sci. Technol. 1995, 29, 1542. (28) Naes, K.; Axelman, J.; Na¨f, C.; Broman, D. Role of Soot Carbon and Other Carbon Matrixes in the Distribution of PAHs among Particles, DOC, and the Dissolved Phase in the Effluent and Recipient Waters of an Aluminum Reduction Plant. Environ. Sci. Technol. 1998, 32, 1786. (29) Bucheli, T. D.; Gustafsson, O ¨ . Ubiquitous observations of enhanced soild affinities for aromatic organochlorines in field situations: Are in situ dissolved exposures overestimated by existing partitioning models? Environ Toxicol. Chem. 2001, 20, 1450. (30) Gustafsson, O ¨ .; Haghseta, K.; Chan, F. McFarlane, A.; Gschwend, P. M. Quantification of the Dilute Sedimentary Soot Phase: Implications for PAH Speciation and Bioavailability. Environ. Sci. Technol. 1997, 31, 203. (31) Maruya, K. A.; Riseborough, R. W.; Horne, A. J. Partitioning of Polynuclear Aromatic Hydrocarbons between Sediments from San Francisco Bay and Their Porewaters. Environ. Sci. Technol. 1996, 30, 2942. (32) Hawthorne, S. B.; Miller, D. J. Evidence for Very Tight Sequestration of BTEX Compounds in Manufactured Gas Plant Soils Based on Selective Supercritical Fluid Extraction and Soil/Water Partitioning. Environ. Sci. Technol. 2003, 37, 3587. (33) Ehlers, L. J.; Luthy, R. G. Contaminant bioavailability in soil and sediment. Environ. Sci. Technol. 2003, 295A. (34) Hong, L.; Ghosh, U.; Mahajan, T.; Zare, R. N.; Luthy, R. G. PAH Sorption Mechanism and Partitioning Behavior in LampblackImpacted Soils from Former Oil-Gas Plant Sites. Environ. Sci. Technol. 2003, 37, 3625. (35) Jonker, M. T. O.; Smedes, F. Preferential Sorption of Planar Contaminants in Sediments from Lake Ketelmeer, The Netherlands. Environ. Sci. Technol. 2000, 34, 1620. (36) Lohmann, R.; MacFarlane, J. K.; Gschwend, P. M. On the importance of black carbon to sediment-water equilibria of PAHs, PCBs, and PCDDs. In Preprints of Abstracts; ACS Symposium, Boston, MA, August 18-22, 2002; Amercian Chemical Society: Washington, DC, 2002. (37) Booij, K.; Hoedemaker, J. R.; Bakker, J. F. Dissolved PCBs, PAHs, and HCB in Pore Waters and Overlying Waters of Contaminated Harbor Sediments. Environ. Sci. Technol. 2003, 37, 4213. (38) Socha, S. B.; Carpenter, R. Factors affecting pore water hydrocarbon concentrations in Puget Sound sediments. Geochim. Cosmochim. Acta 1989, 51, 1273. (39) Lohmann, R.; MacFarlane, J. K.; Gschwend, P. M. Importance of Black Carbon to sorption of native PAHs, PCBs, and PCDDs in Boston and New York Harbor sediments. Environ. Sci. Technol. 2005, 39, 141. (40) Kraaij, H.; Mayer, P.; Busser, F.; Van het Bolscher M.; Seinen, W.; Tolls, J.; Belfroid, A. C. Measured pore-water concentrations make equilibrium partitioning worksa data analysis. Environ. Sci. Technol. 2003, 37, 268. (41) Paine, M. D.; Chapman, P. M.; Allard, P. J.; Murdoch, M. H.; Minifie, D. Limited bioavailability of sediment PAH near an aluminum smelter: Contamination does not equal effects. Environ. Toxicol. Chem. 1996, 11, 2003. (42) Alexander, M. Aging, Bioavailability, and Overestimation of Risk from Environmental Pollutants. Environ. Sci. Technol. 2000, 34, 4259. (43) Tang, J.; Robertson, B. K.; Alexander, M. Chemical-Extraction Methods To Estimate Bioavailability of DDT, DDE, and DDD in Soil. Environ. Sci. Technol. 1999, 33, 4346. (44) White, J.; Kelsey, J. W.; Hatzinger, P. B.; Alexander, M. Factors affecting sequestration and bioavailability of phenanthrene in soils. Environ. Toxicol. Chem. 1997, 16, 2040. (45) Jager, T.; Baerselman, R.; Dijkman, E.; De Groot, A. C.; Hogendoorn, E. A.; De Jong, A.; Kruibosch, J. A. W.; Peijnenburg, W. Availability of PAHs to earthworms (Eisenia andrei, OliVOL. 39, NO. 18, 2005 / ENVIRONMENTAL SCIENCE & TECHNOLOGY

9

6891

(46) (47)

(48)

(49)

(50) (51)

(52) (53) (54) (55)

(56)

(57) (58)

(59)

(60)

(61)

(62) (63) (64) (65) (66)

(67) (68)

gochaeta) in field-polluted soils and soil-sediment mixtures. Environ. Toxicol. Chem. 2003, 22, 767. Thomann, R. V.; Komlos, J. Model of biota-sediment accumulation factors for PAHs. Environ. Toxicol. Chem. 1999, 18, 1060. Farrington, J. W. Fossil fuel aromatic hydrocarbon biogeochemistry in the marine environment: research challenges. In Strategies and Advanced Techniques for Marine Pollution Studies: Mediterranean Sea; Giam, C. S., Dou, H. J. M., Eds.; Springer-Verlag: Berlin, Germany, 1986; pp 113-142. Cretney, W. J.; Yunker, M Concentration dependency of biotasediment accumulation factors for chlorinated dibenzo-pdioxins and dibenzofurans in Dungeness crab (Cancer magister) at marine pulp mill sites in British Columbia, Canada. Environ. Toxicol. Chem. 2000, 19, 3012. Sundelin, B.; Eriksson-Wiklund, A.-K.; Lithner, G.; Gustafsson O ¨ . Evaluation of the role of black carbon in attenuating bioaccumulation of PAHs from field-contaminated sediments. Environ. Toxicol. Chem. 2004, 23, 2611. Chung, N.; Alexander, M. Effect of Concentration on Sequestration and Bioavailability of Two Polycyclic Aromatic Hydrocarbons. Environ. Sci. Technol. 1998, 32, 855. Ten Hulscher, Th. E. M.; Postma, J,; Den Besten, P. J.; Stroomberg, G. J.; Belfroid, A. C.; Wegener, J. W.; Faber, J.; Van der Pol, J. C.; Hendriks, A. J.; Van Noort, P. C. M. Tenax extraction mimics benthic and terrestrial bioavailability of organic compounds. Environ. Toxicol. Chem. 2003, 22, 2258. Thorsen, W. A.; Cope, W. G.; Shea, D. Bioavailability of PAHs: Effects of Soot Carbon and PAH Source. Environ. Sci. Technol. 2004, 38, 2029. Lamoureux, E. M.; Brownawell, B. J. Chemical and biological availability of sediment-sorbed hydrophobic organic contaminants. Environ. Toxicol. Chem. 1999, 18, 1733. Talley, J. W.; Ghosh, U.; Tucker, S. G.; Furey, J. S.; Luthy, R. G. Particle-scale understanding of the bioavailability of PAHs in sediment. Environ. Sci. Technol. 2002, 36, 477. Moermond, C. T. A.; Zwolsman, J. J. G.; Koelmans, A. A. Black carbon and ecological factors affect in situ biota to sediment accumulation factors for hydrophobic organic coumpounds in flood plain lakes. Environ. Sci. Technol. 2005, 39, 3101. Maruya, K. A.; Riseborough, R. W.; Horne, A. J. The Bioaccumulation of Polynuclear Aromatic Hydrocarbons by Benthic Invertebrates in an Intertidal Marsh. Environ. Toxicol. Chem. 1997, 16, 1087. Baumard, P.; Budzinski, H.; Garrigues, P. Polycyclic aromatic hydrocarbons (PAHs) in sediments and mussels of the western Mediterranean sea. Environ. Toxicol. Chem. 1998, 17, 765. Farrington, J. W.; Goldberg, E. D.; Risebrough, R. W.; Martin, J. H.; Bowen, V. T. US “Mussel Watch” 1976-1978: An overview of the trace-metal, DDE, PCB, hydrocarbon, and artificial radionuclide data. Environ. Sci. Technol. 1983, 17, 490. McLeod, P. B.; Van den Heuvel-Greve, M. J.; Allen-King, R. M.; Luoma, S. N.; Luthy, R. G. Effects of Particulate Carbonaceous Matter on the Bioavailability of Benzo[a]pyrene and 2,2′,5,5′Tetrachlorobiphenyl to the Clam, Macoma balthic. Environ. Sci. Technol. 2004, 38, 4549. Tracey, G. A.; Hansen, D. J. Use of Biota-Sediment Accumulation Factors to Assess Similarity of Non-Ionic Organic Chemical Exposure to Benthically-Coupled Organisms of Differing Trophic Mode. Arch. Environ. Contam. Toxicol. 1996, 30, 467. Cornelissen, G.; Rigterink, H.; Ferdinandy, M. M. A.; Van Noort, P. C. M. Rapidly desorbing fractions of PAHs in contaminated sediments as a predictor of the extent of bioremediation. Environ. Sci. Technol. 1998, 32, 966. Alexander, M. How Toxic Are Toxic Chemicals in Soil? Environ. Sci. Technol. 1995, 29, 2713. Loehr, R. C.; Webster, M. T. Behavior of fresh vs aged chemicals in soil. J. Soil Contam. 1996, 5, 361. Hatzinger, P. B.; Alexander, M. Effect of Aging of Chemicals in Soil on Their Biodegradability and Extractability. Environ. Sci. Technol. 1995, 29, 537. Fu, M. H.; Mayton, H.; Alexander, M. Desorption and biodegradation of sorbed styrene in soil and aquifer solids. Environ. Toxicol. Chem. 1994, 13, 749. White, J. C.; Alexander, M. Reduced biodegradability of desorption-resistant fractions of polycyclic aromatic hydrocarbons in soil and aquifer solids. Environ. Toxicol. Chem. 1996, 15, 1973. White, J. C.; Kelsey, J. W.; Hatzinger, P. B.; Alexander, M. Factors affecting sequestration and bioavailability of phenanthrene in soils. Environ. Toxicol. Chem. 1997, 16, 2040. Hawthorne, S. B.; Poppendieck, D. G.; Grabanski, C. B.; Loehr, R. C. Comparing PAH Availability from Manufactured Gas Plant

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(69)

(70)

(71) (72)

(73)

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(79)

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(87)

(88)

Soils and Sediments with Chemical and Biological Tests. 1. PAH Release during Water Desorption and Supercritical Carbon Dioxide Extraction. Environ. Sci. Technol. 2002, 36, 4795. Hawthorne, S. B.; Grabanski, C. B. Correlating Selective Supercritical Fluid Extraction with Bioremediation Behavior of PAHs in a Field Treatment Plot. Environ. Sci. Technol. 2000, 34, 4103. Hawthorne, S. B.; Poppendieck, D. G.; Grabanski, C. B.; Loehr, R. C. PAH Release during Water Desorption, Supercritical Carbon Dioxide Extraction, and Field Bioremediation. Environ. Sci. Technol. 2001, 35, 4577. Guerin, W. F.; Boyd, S. A. Bioavailability of naphthalene associated with natural and synthetic sorbents. Wat. Res. 1997, 31, 1504. Ghosh, U.; Zimmerman, J. R.; Luthy, R. G. PCB and PAH Speciation among Particle Types in Contaminated Harbor Sediments and Effects on PAH Bioavailability. Environ. Sci. Technol. 2003, 37, 2209. Luthy, R. D.; Aiken, G. R.; Brusseau, M. L.; Cunningham, D. S.; Gschwend, P. M.; Pignatello, J. J.; Reinhard, M.; Traina, S. J.; Weber, W. J., Jr.; Westall, J. C. Sequestration of Hydrophobic Organic Contaminants by Geosorbents. Environ. Sci. Technol. 1997, 31, 3341. Kelsey, J. W.; Kottler, B. D.; Alexander, M. Selective chemical extractants to predict bioavailability of soil-aged organic chemicals. Environ. Sci. Technol. 1997, 31, 214. Huang, W.; Peng, P.; Yu, Z.; Fu, J. Effects of organic matter heterogeneity on sorption and desorption of organic contaminants by soils and sediments. Appl. Geochem. 2003, 18, 955. Huang, W.; Weber, W. J., Jr. A Distributed Reactivity Model for Sorption by Soils and Sediments. 10. Relationships between Desorption, Hysteresis, and the Chemical Characteristics of Organic Domains. Environ. Sci. Technol. 1997, 31, 2562. Weber, W. J., Jr.; Kim, S. H.; Johnson, M. D. Distributed Reactivity Model for Sorption by Soils and Sediments. 15. HighConcentration Co-Contaminant Effects on Phenanthrene Sorption and Desorption. Environ. Sci. Technol. 2002, 36, 3625. Weber, W. J., Jr.; McGinley, P. M.; Katz, L. E. A distributed reactivity model for sorption by soils and sediments. 1. Conceptual basis and equilibrium assessments. Environ. Sci. Technol. 1992, 26, 1955. Jonker, M. T. O.; Koelmans, A. A. Sorption of polycyclic aromatic hydrocarbons and polychlorinated biphenyls to soot and sootlike materials in the aqueous environment mechanistic considerations. Environ. Sci. Technol. 2002, 36, 3725. Cornelissen, G.; Gustafsson, O ¨ . The importance of Unburned Coal Carbon, Black Carbon and Amorphous Organic Carbon to Phenanthrene sorption in sediments. Environ. Sci. Technol. 2005, 39, 764. Ran, Y.; Xing, B.; Rao, P. S. C.; Fu, J. Importance of Adsorption (Hole-Filling) Mechanism for Hydrophobic Organic Contaminants on an Aquifer Kerogen Isolate. Environ. Sci. Technol. 2004, 38, 4340. Yang, C.; Huang, W.; Xiao, B.; Yu, Z.; Peng, P.; Fu, J.; Sheng, G. Intercorrelations among Degree of Geochemical Alterations, Physicochemical Properties, and Organic Sorption Equilibria of Kerogen. Environ. Sci. Technol. 2004, 38, 4396. Ghosh, U.; Gillette, J. S.; Luthy, R. G.; Zare, R. N. Microscale Location, Characterization, and Association of Polycyclic Aromatic Hydrocarbons on Harbor Sediment Particles. Environ. Sci. Technol. 2000, 34, 1729. Jonker, M. T. O.; Koelmans, A. A. Polyoxymethylene Solid-Phase Extraction as a Partitioning Method for Hydrophobic Organic Chemicals in Sediment and Soot. Environ. Sci. Technol. 2001, 35, 3742. Persson, N. J.; Gustafsson, O ¨ .; Bucheli, T. D.; Ishaq, R.; Naes, K.; Broman, D. Soot-Carbon Influenced Distribution of PCDD/Fs in the Marine Environment of the Grenlandsfjords, Norway. Environ. Sci. Technol. 2002, 36, 4968. Braida, W. J.; White, J. C.; Ferrandino, F. J.; Pignatello, J. J. Influence of solute concentration on the sorption kinetics of polycyclic aromatic hydrocarbons (PAHs) in soils. Uptake rates. Environ. Sci. Technol. 2001, 35, 2765. Gustafsson, O ¨ .; Gschwend, P. M. Soot as a strong partition medium for polycyclic aromatic hydrocarbons in aquatic systems. In Molecular Markers in Environmental Geochemistry; Eganhouse, R. P., Ed.; ACS Symposium Series 671; American Chemical Society: Washington, DC, 1997;p 365. Cornelissen, G.; Kukulska, Z.; Kalaitzidis, S.; Christanis, K.; Gustafsson, O ¨ . Relations between Environmental Black Carbon Sorption and Geochemical Sorbent Characteristics. Environ. Sci. Technol. 2004, 38, 3632.

(89) Cornelissen, G.; Elmquist, M.; Groth, I.; Gustafsson, O ¨ . Effect of sorbate planarity on environmental Black Carbon sorption. Environ. Sci. Technol. 2004, 38, 3574. (90) Gerde, P.; Muggenburg, B. A.; Lundborg, M.; Dahl, A. R. The rapid alveolar absorption of diesel soot-adsorbed benzo[a]pyrene: bioavailability, metabolism and dosimetry of an inhaled particle-borne carcinogen. Carcinogenesis 2001, 22, 741. (91) Jonker, M. T. O.; Koelmans, A. A. Extraction of polycyclic aromatic hydrocarbons from soot and sediment: Solvent evaluation and implications for sorption mechanism. Environ. Sci. Technol. 2002, 36, 4107. (92) Cornelissen, G.; Gustafsson, O ¨ . Effects of added PAHs and precipitated Humic Acid coatings on Phenanthrene sorption to environmental Black Carbon. Environ. Pollut. 2005, in press. (93) Accardi-Dey, A.; Gschwend, P. M. Reinterpreting literature sorption data considering both absorption into and adsorption onto black carbon. Environ. Sci. Technol. 2003, 37, 99. (94) Bucheli, T. D.; Gustafsson, O ¨ . Quantification of the Soot-Water Distribution Coefficient of PAHs Provides Mechanistic Basis for Enhanced Sorption Observations. Environ. Sci. Technol. 2000, 34, 5144. (95) Ba¨rring, H.; Bucheli, T. D.; Broman, D.; Gustafsson, O ¨ . Sootwater distribution coefficients for polychlorinated dibenzo-pdioxins, polychlorinated dibenzofurans and polybrominated diphenyl ethers determined with the soot cosolvency-column method. Chemosphere 2002, 49, 515. (96) Bucheli, T. D.; Gustafsson, O ¨ . Soot sorption of non-ortho and ortho-substituted PCBs. Chemosphere 2003, 53, 515. (97) Accardi-Dey, A.; Gschwend, P. M. Assessing the Combined Roles of Natural Organic Matter and Black Carbon as Sorbents in Sediments. Environ. Sci. Technol. 2002, 36, 21. (98) Braida, W. J.; Pignatello, J. J.; Lu, Y.; Ravikovitch, P. I.; Neimark, A. V.; Xing, B. Sorption hysteresis of benzene in charcoal particles. Environ. Sci. Technol. 2003, 37, 409. (99) Accardi-Dey, A. M. Black Carbon in marine sediments: quantification and implications for the sorption of polycyclic aromatic hydrocarbons. Ph.D. Thesis, 2003, Massachusetts Institute of Technology, Cambridge, MA. (100) Van Noort, P. C. M.; Jonker, M. T. O.; Koelmans, A. A. Modeling maximum adsorption capacities of soot and soot-like materials for PAHs and PCBs. Environ. Sci. Technol. 2004, 38, 3305. (101) Jonker, M. T. O.; Hawthorne, S. B.; Koelmans, A. A. Extremely slowly desorbing polycyclic aromatic hydrocarbons from soot and soot-like materials: Evidence by supercritical fluid extraction. 2005, revised manuscript submitted. (102) Ribes, S.; Van Drooge, B.; Dachs, J.; Gustafsson, O.; Grimalt, J. O. Influence of Soot Carbon on the Soil-Air Partitioning of Polycyclic Aromatic Hydrocarbons. Environ. Sci. Technol. 2003, 37, 2675. (103) Nguyen, T. H.; Sabbah, I.; Ball, W. P. Sorption Nonlinearity for Organic Contaminants with Diesel Soot: Method Development and Isotherm Interpretation. Environ. Sci. Technol. 2004, 38, 3595. (104) Lohmann, R. The emergence of black carbon as a super-sorbent in environmental chemistry: the end of octanol? Environ. Forensics 2003, 4, 161. (105) Dachs, J.; Eisenreich, S. J. Adsorption onto Aerosol Soot Carbon Dominates Gas-Particle Partitioning of Polycyclic Aromatic Hydrocarbons. Environ. Sci. Technol. 2000, 34, 3690. (106) Bucheli, T. D.; Blum, F.; Desaules, A.; Gustafsson, O ¨ . Polycyclic aromatic hydrocarbons, black carbon, and molecular markers in soils of Switzerland. Chemosphere 2004, 56, 1061. (107) Song, J.; Peng, P.; Huang, W. Black carbon and kerogen in soils and sediments: 1. Quantification and characterization. Environ. Sci. Technol. 2002, 36, 3960. (108) Nguyen, T. H.; Brown, R.; Ball, W. P. An evaluation of thermal resistance as a measure of black carbon content in diesel soot, wood char, and sediment. Org. Geochem. 2004, 35, 217. (109) Yang, Y.; Sheng, G. Enhanced Pesticide Sorption by Soils Containing Particulate Matter from Crop Residue Burns. Environ. Sci. Technol. 2003, 37, 3635. (110) Yang, Y.; Sheng, G. Pesticide adsorptivity of aged particulate matter arising from crop residue burns. J. Agric. Food Chem. 2003, 51, 5047. (111) Cornelissen, G.; Gustafsson, O ¨ . Sorption of Phenanthrene to Environmental Black Carbon in Sediment with and without Organic Matter and Native Sorbates. Environ. Sci. Technol. 2004, 38, 148. (112) Chun, Y.; Sheng, G.; Chiou, C. T.; Xing, B. Compositions and Sorptive Properties of Crop Residue-Derived Chars. Environ. Sci. Technol. 2004, 38, 4649.

(113) Jonker, M. T. O.; Sinke, A. J. C.; Brils, J. M.; Koelmand, A. A. Sorption of Polycyclic Aromatic Hydrocarbons to oil contaminated sediment: unresolved complex? Envrion. Sci. Technol. 2003, 37, 5197. (114) Gustafsson, O ¨ .; Bucheli, T. D.; Kukulska, Z.; Andersson, M.; Largeau, C.; Rouzard, J. N.; Reddy, C. M.; Eglinton, T. I. Evaluation of a protocol for the quantification of black carbon in sediments. Global Biogeochem. Cycles 2001, 15, 881. (115) Goldberg, E. D. Black Carbon in the Environment; John Wiley: New York, 1985. (116) Tissot, B. P.; Welte, D. H. Petroleum Formation and Occurrence; Springer-Verlag: New York, 1984. (117) Middelburg, J. J.; Nieuwenhuize, J.; Van Breugel, P. Black Carbon in marine sediments. Mar. Chem. 1999, 65, 245. (118) Ge´linas, Y.; Prentice, K. M.; Baldock, J. A.; Hedges, J. I. An improved thermal oxidation method for the quantification of soot/graphitic Black Carbon in sediments and soils. Environ. Sci. Technol. 2001, 35, 3519. (119) Schmidt, M. W. I.; Skjemstad, J.; Czimczik, C. I.; Glaser, B.; Prentice, K. M.; Ge´linas, Y.; Kuhlbusch, T. A. J. Comparative analysis of black carbon in soils. Global Biogeochem. Cycles 2001, 15, 163. (120) Schmidt, M. W. I.; Noack, A. G. Black carbon in soils and sediments: Analysis, distribution, implications, and current challenges. Global Biogeochem. Cycles 2000, 14, 777. (121) Elmquist, M.; Gustafsson, O ¨ .; Andersson, P. Quantification of sedimentary black carbon using the chemothermal oxidation method: an evaluation of ex situ pretreatments and standard additions approaches. Limnol. Oceanogr.: Methods 2004, 2, 417. (122) Mannino, A.; Harvey, H. R. Black carbon in estuarine and coastal ocean dissolved organic matter. Limnol. Oceanogr. 2004, 49, 735. (123) Lim, B.; Cachier, H. Determination of black carbon by chemical oxidation and thermal treatment in recent marine and lake sediments and Cretaceous-Tertiary clays. Chem. Geol. 1996, 131, 143. (124) Masiello, C. A.; Druffel, E. R.; Currie, L. A. Radiocarbon measurement of black carbon in aerosols and ocean sediments. Geochim. Cosmochim. Acta 2002, 66, 1025. (125) Verardo, D. J. Charcoal analysis in marine sediments. Limnol. Oceanogr. 1997, 42, 192. (126) Wolbach, W. S.; Anders, E. Elemental carbon in sediments: determination and isotopic analysis in the presence of kerogen. Geochim. Cosmochim. Acta 1989, 53, 1637. (127) Chun, Y.; Sheng, G.; Chiou, C. T. Evaluation of Current Techniques for Isolation of Chars as Natural Adsorbents. Environ. Sci. Technol. 2004, 38, 4227. (128) Kuhlbusch, T. A.; Crutzen, P. J. Toward a global estimate of black carbon in residues of vegetation fires representing a sink of atmospheric CO2 and a source of O2. Global Biogeochem. Cycles 1995, 9, 491. (129) Fernandes, M. B.; Skjemstad, J. O.; Johnson, B. B.; Wells, J. D.; Brooks, P. Characterization of carbonaceous combustion residues. Morphological, elemental and spectroscopic features. Chemosphere 2003, 51, 785. (130) Gustafsson, O ¨ .; Gschwend, P. M. The flux of Black Carbon to surface sediments on the New England continental shelf. Geochim. Cosmochim. Acta 1998, 62, 465. (131) Van den Heuvel, H.; Le Couriaut, T.; McMullen, B. M.; Lozac’h, F.; Van Noort, P. C. M. Maximum capacities for adsorption of phenantrene in the slowly and very slowly desorbing domains in 19 soils and sediments. Environ. Toxicol. Chem. 2005, 24, 830. (132) Buckley, D. R.; Rockne, K. J.; Li, A.; Mills, W. J. Soot Deposition in the Great Lakes: Implications for Semi-Volatile Hydrophobic Organic Pollutant Deposition. Environ. Sci. Technol. 2004, 38, 1732. (133) Muri, G.; Cermelj, B.; Faganeli, J.; Brancelj, A. Black carbon in Slovenian alpine lacustrine sediments. Chemosphere 2002, 46, 1225. (134) Reddy, C. M.; Pearson, A.; Xu, L.; McNichol, A. P.; Benner, B. A., Jr.; Wise, S. A.; Klouda, G. A.; Currie, L. A.; Eglinton, T. I. Radiocarbon as a tool to apportion the sources of polycyclic aromatic hydrocarbons and black carbon in environmental samples. Environ. Sci. Technol. 2002, 36, 1774. (135) American Society for Testing and Materials (ASTM). Preparing coal samples for microscopical analysis by reflected light. In Annual book of ASTM Standards, Part 26, D2979, Gaseous Fuels: Coal and Coke; ASTM: West Conshohocken, PA, 1996; p 270. VOL. 39, NO. 18, 2005 / ENVIRONMENTAL SCIENCE & TECHNOLOGY

9

6893

(136) Griffin, J. J.; Goldberg, E. D. The fluxes of elemental carbon in coastal sediments. Limnol. Oceanogr. 1975, 20, 456. (137) Renberg, I.; Wik, M. Soot particle counting in recent lake sediments: an indirect dating method. Ecol. Bull. 1985, 37, 53. (138) Griffin, J. J.; Goldberg, E. D. Impact of fossil fuel combustion on sediments of Lake Michigan: a reprise. Environ. Sci. Technol. 1983, 17, 244. (139) Currie, L. A.; Benner, B. A., Jr.; Kessler, J. D.; Klinedinst, D. B.; Klouda, G. A.; Marolf, J. V.; Slater, J. F.; Wise, S. A.; Cachier, H.; Cary, R.; Chow, J. C.; Watson, J.; Druffel, E. R. M.; Masiello, C. A.; Eglinton, T. I.; Pearson, A.; Reddy, C. M.; Gustafsson, O ¨ .; Quinn, J. G.; Hartmann, P. C.; Hedges, J. I.; Prentice, K. M.; Kirchstetter, T. W.; Novakov, T.; Puxbaum, H.; Schmid, H. A critical evaluation of interlaboratory data on total, elemental, and isotopic carbon in the carbonaceous particle reference material, NIST SRM 1649a. J. Res. Natl. Inst. Stand. Technol. 2002, 107, 279. (140) Schmidt, M. W. I.; Skjemstad, J. O.; Gehrt, E.; Ko¨gel-Knabner, I. Charred organic carbon in German chernozemic soils. Eur. J. Soil Sci. 1999, 50, 351. (141) Skjemstad, J. O.; Clarke, P.; Taylor, J. A.; Oades, J. M.; McClure, S. G. The chemistry and nature of protected carbon in soils. Austr. J. Soil Res. 1996, 34, 251. (142) Senftle, J. T.; Landis, C. R.; McLaughlin, R. L. Organic petrographic approach to kerogen characterization. In Organic Geochemistry; Engel, M. H., Macko, S. A., Eds.; Plenum Press: New York, 1993. (143) Ran, Y.; Xiao, B.; Huang, W.; Peng, P.; Liu, D.; Fu, J.; Sheng, G. Kerogen in aquifer material and its strong sorption for nonionic organic compounds. J. Environ. Qual. 2003, 32, 1701. (144) Cornelissen, G.; Haftka, J.; Parsons, J.; Gustafsson, O ¨ . Sorption to Black Carbon of organic compounds with varying polarity and planarity. Environ. Sci. Technol. 2005, 39 (10), 3688-3694. (145) Van Noort, P. C. M. A thermodynamics-based estimation model for adsorption of organic compounds by carbonaceous materials in environmental sorbents. Environ. Toxicol. Chem. 2003, 22, 1179. (146) Falconer, R. L.; Bidleman, T. F.; Cotham, W. E. Preferential Sorption of Non- and Mono-ortho-polychlorinated Biphenyls to Urban Aerosols. Environ. Sci. Technol. 1995, 29, 1666. (147) Kulikova, N. A.; Perminova, I. V. Binding of Atrazine to Humic Substances from Soil, Peat, and Coal Related to Their Structure. Environ. Sci. Technol. 2002, 36, 3720. (148) Schwarzenbach, R. P.; Gschwend, P. M.; Imboden, D. M. Environmental Organic Chemistry, 2nd ed.; John Wiley and Sons Inc.: New York, 2003. (149) Zhu, D.; Hyun, S.; Pignatello, J. J.; Lee, L. S. Evidence for π-π Electron Donor-Acceptor Interactions between π-Donor Aromatic Compounds and π-Acceptor Sites in Soil Organic Matter through pH Effects on Sorption. Environ. Sci. Technol. 2004, 38, 4361. (150) Mastral, A. M.; Garcia, T.; Callen, M. S.; Lopez, J. M.; Navarro, M. V.; Murillo, R.; Galban, J. Three-Ring PAH Removal from Waste Hot Gas by Sorbents: Influence of the Sorbent Characteristics. Environ. Sci. Technol. 2002, 36, 1821. (151) Vorres, K. S. The Argonne Premium Coal Sample Program. Energy Fuels 1990, 4, 420. (152) Van Noort, P. C. M.; Cornelissen, G.; Ten Hulscher, Th. E. M.; Vrind, B. A.; Rigterink, H.; Belfroid, A. C. Slow and very slow desorption of organic compounds from sediment: influence of sorbate planarity. Water Res. 2003, 37, 2317. (153) Jonker, M. T. O.; Hoenderboom, A.; Koelmans, A. A. Effects of sedimentary sootlike materials on bioaccumulation and sorption of polychlorinated biphenyls. Environ. Toxicol. Chem. 2004, 23, 2563. (154) Kilduff, J. E.; Wigton, A. Sorption of TCE by Humic-Preloaded Activated Carbon: Incorporating Size-Exclusion and Pore Blockage Phenomena in a Competitive Adsorption Model. Environ. Sci. Technol. 1999, 33, 250. (155) Carter, M. C.; Weber, W. J., Jr. Modeling Adsorption of TCE by Activated Carbon Preloaded by Background Organic Matter. Environ. Sci. Technol. 1994, 28, 614. (156) Karapanagioti, H. K.; James, G.; Sabatini, D. A.; Kalaitzidis, S.; Christanis, K.; Gustafsson, O ¨ . Evaluating charcoal presence in sediments and its effect on phenanthrene sorption. Water, Air Soil Pollut. 2004, 4, 359. (157) Salloum, M. J.; Chefetz, B.; Hatcher, P. G. Phenanthrene Sorption by Aliphatic-Rich Natural Organic Matter. Environ. Sci. Technol. 2002, 36, 1953. 6894

9

ENVIRONMENTAL SCIENCE & TECHNOLOGY / VOL. 39, NO. 18, 2005

(158) Xing, B.; Pignatello, J. J. Competitive Sorption between 1,3Dichlorobenzene or 2,4-Dichlorophenol and Natural Aromatic Acids in Soil Organic Matter. Environ. Sci. Technol. 1998, 32, 614. (159) Xing, B.; Pignatello, J. J.; Gigliotti, B. Competitive Sorption between Atrazine and Other Organic Compounds in Soils and Model Sorbents. Environ. Sci. Technol. 1996, 30, 2432. (160) Baker, J. E.; Eisenreich, S. J.; Eadle, B. J. Sediment trap fluxes and benthic recycling of organic carbon, PAHs and PCB congeners in Lake Superior. Environ. Sci. Technol. 1991, 25, 500. (161) Broman, D.; Na¨f, C.; Rolff, C.; Zebu ¨ hr, Y. Occurrence and dynamics of PCDDs and PCDFs and PAHs in the mixed surface layer of remote coastal and offshore waters of the Baltic. Environ. Sci. Technol. 1991, 25, 1850. (162) Rockne, K. J.; Shor, L. M.; Young, L. Y.; Taghton, G. L.; Kosson, D. S. Distributed Sequestration and Release of PAHs in Weathered Sediment: The Role of Sediment Structure and Organic Carbon Properties. Environ. Sci. Technol. 2002, 36, 2636. (163) Cornelissen, G.; Rigterink, H.; Vrind, B. A.; Ten Hulscher, Th. E. M.; Ferdinandy, M. M. A.; Van Noort, P. C. M. Two-stage desorption kinetics and in situ partitioning of hexachlorobenzene and dichlorobenzenes in a contaminated sediment. Chemosphere 1997, 35, 2405. (164) Xing, B.; Pignatello, J. J. Increasing isotherm nonlinearity with time for organic compounds in natural organic matter: Implications for sorption mechanisms. Environ. Toxicol. Chem. 1996, 15, 1282. (165) Cornelissen, G.; Gustafsson, O ¨ . Prediction of large variation in BSAFs due to concentration-dependent Black Carbon adsorption of Planar Hydrophobic Organic Compounds. Environ. Toxicol. Chem. 2005, 24, 495. (166) Lohmann, R.; Burgess, R. M.; Cantwell, M. G.; Ryba, S. A.; MacFarlane, J. K.; Gschwend, P. M. Dependency of Polychlorinated Biphenyl and Polycyclic Aromatic Hydrocarbon Bioaccumulation in Mya arenaria on Both Water Column and Sediment Bed Chemical Activities. Environ. Toxicol. Chem. 2004, 23, 2551. (167) Mayer, P.; Vaes, W. H. J.; Wijnker, F.; Legierse, K. C. H. M.; Kraaij, H.; Tolls, J.; Hermens, J. L. M. Sensing Dissolved Sediment Porewater Concentrations of Persistent and Bioaccumulative Pollutants Using Disposable Solid-Phase Microextraction Fibers. Environ. Sci. Technol. 2000, 34, 5177. (168) Heringa, M. Free concentration as target dose estimate. Ph.D. Thesis, Utrecht University, Utrecht, The Netherlands, 2004. (169) Escher, B. I.; Hermens, J. L. M. Internal Exposure: Linking Bioavailability to Effects. Environ. Sci. Technol. 2004, 38, 455A462A. (170) National Research Council. Bioavailability of Contaminants in Soils and Sediments: Processes, Tools and Applications; National Academies Press: Washington, DC, 2002. (171) Paserba, K. R.; Gellman, A. J. Kinetics and energetics of oligomer desorption from surfaces. Phys. Rev. Lett. 2001, 86, 4338. (172) Simoneit, B. R. T. Biomass burningsa review of organic tracers for smoke from incomplete combustion. Appl. Geochem. 2002, 17, 129. (173) Simoneit, B. R. T.; Schauer, J. J.; Nolte, C. G.; Oros, D. R.; Elias, V. O.; Fraser, M. P:; Rogge, W. F.; Cass, G. R. Levoglucosan, a tracer for cellulose in biomass burning and atmospheric particles. Atmos. Environ. 1999, 33, 173. (174) Hays, M. D.; Geron, C. D.; Linna, K. J.; Smith, N. D.; Schauer, J. J. Speciation of Gas-Phase and Fine Particle Emissions from Burning of Foliar Fuels. Environ. Sci. Technol. 2002, 36, 2281. (175) Schauer, J. J.; Cass, G. R. Source Apportionment of Wintertime Gas-Phase and Particle-Phase Air Pollutants Using Organic Compounds as Tracers. Environ. Sci. Technol. 2000, 34, 1821. (176) Benner, B. A., Jr.; Wise, S. A.; Currie, L. A.; Klouda, G. A.; Klinedinst, D. B.; Zweidinger, R. B.; Stevens, R. K.; Lewis, C. W. Distinguishing the Contributions of Residential Wood Combustion and Mobile Source Emissions Using Relative Concentrations of Dimethylphenanthrene Isomers. Environ. Sci. Technol. 1995, 29, 2382. (177) Mandalakis, M.; Gustafsson, O ¨ .; Reddy, C. M.; Xu, L. Radiocarbon apportionment of fossil versus biofuel combustion sources of polycyclic aromatic hydrocarbons in the Stockholm metropolitan area. Environ. Sci. Technol. 2004, 38, 5344. (178) Ishiguro, T.; Takatori, Y.; Akihama, K. Microstructure of diesel soot particles probed by electron microscopy: first observation of inner core and outer shell. Combust. Flame 1997, 108, 231.

(179) Stanmore, B. R.; Brilhac, J. F.; Gilot, P. The oxidation of soot: a review of experiments, mechanisms and models. Carbon 2001, 39, 2247. (180) Rockne, K. J.; Taghon, G. L.; Kosson, D. S. Pore Structure of Soot Deposits from Several Combustion Sources. Chemosphere 2000, 41, 1125. (181) NIST. Certificate of Analysis, Standard Reference Material 1650a; National Institute of Standards and Technology: Gaithersburg, MD, 2000. (182) Posfai, M.; Gelencser, A.; Simonics, R.; Arato, K.; Li, J.; Hobbs, P. V.; Buseck, P. R. Atmospheric tar balls: Particles from biomass and biofuel burning. J. Geophys. Res. 2004, 109, 6213. (183) LeBoeuf, E. J.; Weber, W. J., Jr. A Distributed Reactivity Model for Sorption by Soils and Sediments. 8. Sorbent Organic Domains: Discovery of a Humic Acid Glass Transition and an Argument for a Polymer-Based Model. Environ. Sci. Technol. 1997, 31, 1697.

(184) Guo, L.; Semiletov, I.; Gustafsson, O ¨ .; Ingri, J.; Andersson, P.; Dudarev, O.; White, D. Characterization of Siberian Arctic coastal sediments: Implications for terrestrial organic carbon export. Global Biogeochem. Cycles 2004, 18, GB1036. doi: 10.1029/2003GB002087. (185) Masiello, C. A.; Druffel, E. R. Black carbon in deep-sea sediments. Science 1998, 280, 1911. (186) Mitra, S.; Bianchi, T. S.; McKee, B. A.; Sutula, M. Sources and seasonal discharge of fossil fuel-derived fluvial black carbon from the Mississippi River: implications for the global carbon cycle. Environ. Sci. Technol. 2002, 36, 2296.

Received for review January 28, 2005. Revised manuscript received July 1, 2005. Accepted July 1, 2005. ES050191B

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