Environ. Sci. Techno/. 1995, 29, 2519-2527
Spatial and Temporal Distribution, Fluxes, and Budsets of Omanochlorinated Comnounds in Nchhwest Mediterranein I M M A C U L A D A TOLOSA, JOSEP M. BAYONA, AND JOAN ALBAIGES* Department of Environmental Chemistry, Centro de Investigacidn y Desarrollo (C.S.I.C.), Jordi Girona Salgado 18-26, Barcelona, E-08034 Spain
A total of 30 NW Mediterranean surficial sediment samples collected in the prodeltas of the Rhone and Ebro Rivers, continental shelf, slope, and deep basin were analyzed for 12 individual polychlorinated biphenyl (PCB) congeners, chlorinated diphenylethane pesticides (2,4‘- and 4,4’-DDT and their metabolites), and hexachlorobenzene (HCB). The spatial distribution of the PCB congeners and their concentrations illustrate the relative contribution to the pollution burden in the NW Mediterranean basin of river inputs, urban sewage disposal, and atmospheric deposition, the latter particularly relevant in the deep basin. Estimates of annual fluxes of these compounds in the N W Mediterranean sediments were from 0.5 to 1580pg/m2forPCBs (in Clophen A60 equivalents), from 0.3 to 2060 ,ug/m2 for DDTs (DDT DDE DDD), and from 0.02 to 170 , u g h 2 for HCB. These results account for an accumulation rate in the whole area of 2705 kg/year for PCBs, 2030 kg/year for DDTs, and 205 kg/year for HCB. However, the major accumulation of organochlorinated compounds was found to occur in the prodelta areas with an apparent decrease in the Rhone area during the last 15 years, but not in the Ebro, probably reflecting the earlier banning of the usage of these compounds in that region.
+
+
Introduction Organochlorinated (OC) compounds, namely, DDTs and PCBs, are ubiquitous contaminants whose occurrence in the environment is of special concern because of their resistance to degradation and the toxicity of some of their constituents (1,2). Recent surveys carried out on a global basis have shown their widespread distribution, particularly in the marine environment ( 3 , 4 ) . Long-range atmospheric transport and deposition have been found partially responsible for this distribution and particularly for the background levels found in remote areas (5). * F a : 34-3-2045904.
0013-936W95/0929-2519$09.00/0
@ 1995 American
Chemical Society
In the Mediterranean region, monitoring activities initiated in the 1970s as a result of the implementation of the Barcelona Convention led to the recognition of point sources and the main regions of concentration for these compounds (6-8). The industrial production of PCBs in the region maximized in the mid- 1970s,in France and Spain accounting for 9.6 and 1.9 ktlyear, respectively (6). This production figure contrasts with an earlier banning in other industrialized countries (Le., United States, Japan, U.K.). A similar trend occurred for DDTs, which were banned in Europe in 1979. The potential release ofhexachlorobenzene (HCB) into the environment is more difficult to estimate due to the fact that, beside its past usage as a biocide, it is formed as a byproduct in several industrial processes. In this respect, in the late 1970s the Western European production was estimated as 30 ktlyear (91, whereas Spain only accounted for 1 ktlyear. Current knowledge on the environmental levels of OC compounds in the NW Mediterranean sediments is restricted to the vicinities of point pollution sources (6-8, 10);therefore, the knowledge of their ultimate fate in the basin is rather poor. Nevertheless, a preliminary mass balance for PCBs in the Western Mediterranean has been published (11) and recently updated (12). The aim of this work was the calculation of depositional fluxes of representative OC pesticides and PCB components in NW Mediterranean sediments in order to estimate the load of these refractory pollutants in the basin. The compounds selected for study were 12 individual PCB congeners (IUPAC Nos. 52,101,118 149,153 + 132,138 158,187,128,180,and 1701, includingthe most abundant components from tetra- to heptachlorinated species and the set of sixrecommendedfor analysis by ICES (13). These congeners may coelute with minor constituents in the analytical conditions used in this work (14). However, the bias associated to such coelutions is negligible due to their low abundance. The quantitation of PCBs as individual congeners has not been currently used in the region despite the fact that this is known to improve the accuracy of their determination (15)and to enable a better insight into the biogeochemical processes during transport and sedimentation. The following compounds were also included in this study: 1,1,1trichloro-2-(2-chlorophenyl) -244-chloropheny1)ethane(2,4’DDT); 1,1,l-trichloro-2,2-bis(4-chlorophenyl)ethane (4,4’DDT); 1,l-dichloro-2(2-chlorophenyl)-2(4-chlorophenyl)ethane (2,4’-DDD); 1,1-dichloro-2,2-bis(4-chlorophenyl) ethane (4,4’-DDD); 1,l-dichloro-2-(2-chlorophenyl)-2- (4chloropheny1)ethylene (2,4’-DDE);l,l-dichloro-2,2-bis(4chloropheny1)ethylene(4,4’-DDE);and hexachlorobenzene (HCB). For simplicity, the following nomenclature will be used in this paper: DDDs for the sum of 2,4’- and 4,4’DDD; DDEs for the sum of 2,4‘- and 4,4’-DDE;DDTs for the sum of 2,4’- and4,4’-DDT; and tDDTs for the sum of DDDs, DDEs, and DDTs. Furthermore,the sum of the 12 individual PCB congeners will be referred to as PCBs. Special attention was devoted to urban areas and the Rhone and Ebro estuaries as potential point sources of OC compounds in the region. In this respect, several radial transects were sampled seaward from these points for assessing transport and depositional processes in the basin.
+
+
VOL. 29. NO. 10, 1995 /ENVIRONMENTAL SCIENCE &TECHNOLOGY
2519
FIGURE 1. Area of study and sampling site locations.
In addition, two dated sediment cores, representative of the Rhone and Ebro prodeltas, were analyzed for OC compounds in order to investigate their historical trends in the Provencal and Catalan regions where production patterns were differentand environmental regulations came into effect at different periods.
Experimental Section Environmental Setting. The NW Mediterranean basin (Figure 1) has a surface area of ca. 2.8 x IO5 Kmz. The predominant surficial sea current in the continental shelf andslopeisfromNE toSWsweepingthe coastsofNorthem Italy, France, and Spain (14). The Rhone and Ebro Rivers, with average flow rates of 1710 and 250 m3/s, respectively, are themajorfreshwaterinputs in thearea. Whiie the Rhone River basin is highly industrialized, in the catchment area of the Ebro River agricultural practices predominate. Barcelonaand Marseillewith respectively2.5and 1.0 million inhabitants are the main coastal urban centers. Wastewaters of the largest cities are subjected to primary treatment processes, and the resultant sewage is discharged via submarine outfalls into the continental shelf. The population in the coastal area has a marked seasonal pattern due to the importance of tourism in the region. The main industrial areas are located in the Gulf of Fos (West Marseille)and nearby Tarragona and Barcelona (Figure I ) . Sampling. A series of sediment stations covering the whole basin from IO to 2700 m water depth were box-cored during several oceanographic cruises from 1987 to 1991 (Table I). Subsamples were obtained with stainless steel tubing (6 cm i.d. x 40 cm long) endcapped with FTFE stoppers. Sampleswere frozen at -20 T immediatelyafter 2 5 2 0 . ENVIRONMENTAL SCIENCE & TECHNOLOGY I VOL. 29. NO. 10,1995
collection and were kept in an upward vertical position. Sediment extrusion from the tubing was carried out in a clean laboratory by pulling the partially thawed sample from bottomto topwithaPTFE-coatedpiston. Theextemal part of the sample that was in contact with the sampling tubingwas removed to avoid smearingduring the extrusion process, and the top surface centimeter was recovered by cutting for analysis. Simultaneously, subsamples obtained with a PVC tubing (6 cm i.d. x 30 cm length) were collected for 210Pbdating. Sample handling was similar to that described above for OC compound analyses. The stations were included in radial transects seaward ofthemouthsoftheEbro (BC7-9andll:Cl andD1-3)and Rhone Rivers (RD5-8, IO, and 11) for evaluating the deposition of contaminants from land-based sources. Another group ofsamplingsiteslocatedin theGulfofLions W8, 14, and 23; BC4-6) was selected to estimate the transport of contaminants from the Rhone Estuary by the Ligurian-Provenpl Sea current. A transect containing four sampling sites located in front of Barcelona (AI,A2,BCIO, and "27) was also chosen to evaluate the impact of both point and diffuse pollution sources. Finally, a group of samples (TY19, 17, and 3; BC8, 14, and 15) was obtained in the slope and deep sea basin to evaluate the long-range transport of contaminants. Furthermore, two sediment samples representative of the Rhone and Ebro prodeltas (BC4 and BCS, respectively) were analyzed in depth [0-3, 3-6,6-10, 10-14, 14-22 (Ebro),plus 22-30 cm (Rhone) from the top] in order to ascertain the historical trends of deposition of OC pollutants in the basin. Materials. Octachloronaphthalene (OCN): individual PCB congeners (IUPAC Nos. 52, 101, 118, 153, 138, 187,
TABLE 1
Site location and Sedimentation Characteristics k d b
station
date
location
BC4 BC5 BC6 BC7 BC8 BC9 BCIO BC11 BC12 BC14 BC15 AI A2 c1 D1 D2 D3 TY3 TY8 TY14 TY17 TY19 TY23 TY27 RD5 RD6 RD7 RD8 RDIO RD11
5-90 5-90 5-90 5-90 5-90 5-90 5-90 5-90 5-90 5-90 5-90 9-90 9-90 9-90 9-90 9-90 9-90 11-91 11-91 11-91 11-91 11-91 11-91 11-91 06-87 07-88 07-87 07-87 07-87 07-87
04"51'E, 43"09 N 03"41'E, 42"19 N 03'25'E, 42"51'N 00'53' E, 40'46 N 0Io23'E, 40'23'N OIDO3E,40°53'N 02'09E, 40"58 N 00"43'E, 4O03O'N 01"51'E, 4O0O3'N 04"40 E, 42"OO'N 05'56E, 41'57" 02'11'E, 41"18 N 02"13'E, 41"15'N 00"58E, 40'44'N 0O054'E, 40'40' N OOo55E, 40"35'N 01"03'E, 40'03N 06"30E, 40"39 N 04"54'E, 42"52'N 04"20'E, 42"50'N 05"01'E, 40'41" 03"51'E, 41'31" 03"46E, 43"13'N 02"19E, 40'39" 04"51'E, 43"18'N 04"50'E, 43"18 N 04"51'E, 43'17'N 04"50E, 43'15N 04"18'E, 43'18" 04"52'E, 43"19'N
hc
depth TOC (crn/ (cmy (rn) RAP ( O h ) year) year) 101 760 85 11 520 75 1080 30 1790 2390 2500 57 200 51 20 52 148 2700 840 412 2673 2290 82 1906 23 25 77 90 42 40
MD MD MD MD MD MD MD MD MD MD MD GC GC GC GC GC GC TY TY TY TY TY TY TY GP GP GP GP GP GP
0.83 0.94 0.91 0.75 0.72 0.71 0.95 1.02 1.12 0.70 1.19 1.85 0.80 1.18 1.08 0.97 0.38 1.40 0.95 1.22 1.47 0.85 1.03 0.81 1.61 2.28 1.42 1.53 1.02 1.72
0.20 6.0 0.09 3.0 0.13 1.5
nd
nd
0.15 2.3 0.20 2.0 0.07 0.5
nd
nd
0.05 0.2 0.03 0.0 0.02 0.0
nd
nd
0.14 nd 0.21 nd
nd
nd
0.36 nd 0.22 nd 0.01 nd
nd nd 0.01 0.05 0.10
nd >0.6 20.6 >0.6 -0.6
>0.6 20.6
nd nd nd nd nd nd nd nd nd nd nd nd
a Research vessel. MD, Marione Dufresne; GC, Garcia de/ Cid; Ty, Tyro; GP, George Petit. Sedimentation rate. Mixing rate. dnd, not determined.
128, 180, and 170);2,4'-DDE; 2,4'- and 4,4'-DDD; and 2,4'DDT were obtained in isooctane solutions of 10 ng/mL from Dr. Ehrenstorfer (Augsburg, Germany). Neat (99%) 4,4'-DDE and 4,4'-DDT were purchased from Polyscience (Niles, IL), and neat HCB (97%)was from Aldrich Chemical Co. (Milwaukee, WI). All solvents used were pesticide grade or better. Diethyl ether was obtained from Carlo Erba Farmitalia (Milan,Italy). n-Hexane,methanol, and dichloromethane were purchased from Scharlau (Barcelona,Spain). Florisil (60-100 mesh), sodium sulfate, copper powder, and isooctane were obtained from Merck (Darmstadt, Germany). Analytical Procedures. Freeze-dried sediments (5- 15 g drywt) were spiked (2-250 ng depending on the sampling area) with OCN as the recovery standard. As the same samples were also analyzed for hydrocarbons, squalane was added as the internal standard for calculating the recovery of these fractions. Soxhlet extraction was performed with dichloromethane/ methanol (2:1)for 36 h. In order to avoid losses of the most volatile compounds, the resulting organic extracts were concentrated to 0.5- 1mL in a rotary evaporator, adsorbed onto 2 g of anhydrous sodium sulfate, and dried under a gentle stream of nitrogen. The adsorbed organic extracts were transferred on top of a glass column (35 cm x 0.9 i.d.) slurry packed with 5 g of activated (120 "C) Florisil. The following fractions were recovered: (I) 40 mL of n-hexane [PCBS,2,4'-, 4,4'-DDE, HCB, 4,4'-DDT (partially)] and (11) 20 mL of 10% diethyl ether in n-hexane [4,4'-DDD, 4,4'DDT (partially),OCNI. Elemental sulfur was removed from fraction I by activated copper (sonicated three times with
HC135.5%;rinsed three times with distilled water, acetone, and hexane) treatment for 12 h at room temperature prior to gas chromatographic determination. Subsamples taken for TOC determination were pretreated with 7 N HC1 for carbonate removal and then analyzed in a Fisons 1106CHN analyzer (Milan, Italy). The determination of OC compounds was peformed by capillary gas chromatography with electron capture detection (cGC-ECD) with a Hewlett-Packard 5890 instrument equipped with an HP autosampler 7673A. On the other hand, the recovery of the first fraction was obtained from squalane determined by cGC-FID. Samples were injected under splitless conditions at 270 "C, and the detector temperature was held at 310 "C. The analytical column was a DB-5 of 30 m x 0.25 mm i.d. (0.25pm film thickness). The oven temperature was programmed from 60 to 100 "C at 15 "Urnin and then from 100 to 300 "C at 6 "Clmin, holding the final temperature for 10 min. Helium was used as carrier gas at 2 mL/min. Confirmatory analyses were performed by cGClMS in the negative ion chemical ionization mode, as described elsewhere (17). Quantification was performed by the external standard procedure using a calibration mixture containing all target analytes. Individual calibration plots were linear from 0.01 to 1.2 ng (r > 0.997). Internal standard recoveries obtained in real samples ranged from 70 to 90%, and fortified sediments with the same calibration mixture were higher than 70%with RSD lower than 20% (n = 5). Analytical data were corrected for recoveries using the above-mentioned internal standards. Procedural blanks were obtained for every set of five samples and were processed in the manner as described above. Accumulation and mixing rates in the sediments analyzed were provided by Zuo et al. (18,191 using210Pbdating. Briefly, sediment cores were X-rayed and sectioned in 1-cm intervals in the upper 10 cm and at 2-3 cm thereafter in order to get higher resolution in the more recent section. Cores taken in the vicinities of the river mouths (Ebro and Rhone) showed vertical well-mixed activity profiles of *lOPb,indicating a strong sediment mixing and/or deposition. The mixing coefficient ranged from 0.002 to 7 and from 0.2 to 2.3 cm2/year in the Rhone and Ebro prodeltas, respectively (Table 1). The deposition rates were 0.0250.4 cmlyear for the former area and 0.05-0.2 cm/year for the latter. In the cores collected from the deeper basin (>2000 m),the excess of210Pbdecreased exponentiallywith depth to a constant background value, indicating that the surface layer was undisturbed. Depositional fluxes of pollutants onto the sediments were obtained from geochronological data (210Pb) and sediment densities provided by Zuo et al. (18, 19) (Table 1).
Results and Discussion Sources and Distribution of Polychlorinated Biphenyls. PCBs are ubiquitously distributed in the NWMediterranean surficial sediments. The individual concentrations of selected congeners are reported in Table 2. The congener distributions are generally dominated by hexa- and heptachloro-substituted species paralleling those found in highly chlorinated commercial formulations. In fact, the multiple linear correlation between the PCB congener concentrations of the sediment samples and those of commercial mixtures (e.g., Clophen and Aroclor) showed VOL. 29, NO. 10,1995 / ENVIRONMENTAL SCIENCE &TECHNOLOGY
2521
TABLE 2
Individual Concentrations (ndg, dry wt) of PCB Congeners, DDTs, and HCP (4)
101 (5)
118+149 f5W
153 (6)
138 (6)
187 (7)
128
station
RD-5 RD-6 RD-7 RD-8 RD-10 RD-11
6.8 2.2 10.0 6.0 5.0 9.1
9.4 3.1 13.0 9.4 6.9 14.4
20.6 3.0 29.4 19.9 16.1 41.3
19.5 9.8 28.2 22.1 14.5 38.9
19.4 6.5 29.4 23.8 13.5 38.3
11.1 3.5 15.8 13.9 8.1 19.9
3.4 0.6 4.9 3.6 2.5 7.0
TY-8 TY-14 TY-23 BC4 BC6 BC5
0.1 0.3 0.5 0.3 0.3 0.2
0.2 0.4 0.6 0.5 0.4 0.4
0.7 1.o 1.6 1.3 0.9 1.o
0.7 1.0 1.5 1.0 0.8 1.1
0.9 1.4 2.1 1.1 0.9 1.3
0.3 0.4 0.6 0.4 0.3 0.3
0.1 0.2 0.2 0.2 0.1 0.2
0.7 0.9 1.1 0.8 0.5 0.9
BC7 c1 BCll D1 D2 BC9 D3
1.2 0.7 0.3 1.5 0.9 0.2 nd
1.5 1.4 0.6 1.7 1.5 0.3 0.2
2.2 4.2 1.3 5.6 5.3 0.6 0.4
1.7 3.5 1.4 4.3 4.5 0.5 0.2
1.8 4.3 1.5 5.4 5.1 0.7 0.3
1.0 0.3 2.4 0.6 0.2 0.9 0.6 3.1 0.7 2.9 0.3 0.1 0.1 nd
2.1 4.0 1.9 6.5 6.0 0.3 0.2
AI A2 BClO
2.5 0.3 0.2
5.4 0.4 0.3
13.9 0.4 0.9
7.7 0.7 0.6
10.7 1.0 0.9
0.1 0.1 0.1 0.2 0.1 0.1 0.2 0.4
0.3 0.2 0.2 0.4 0.2 0.3 0.4 0.9
0.2 0.2 0.2 0.3 0.2 0.3 0.4 1.0
0.3 0.2 0.3 0.5 0.3 0.4 0.6 1.3
52
IS)
180 (7)
170 (7)
2,4'-DDD L4-DDE 2,4-DDT 4,4'-DDE 4,4-DDD 4,4-DDT
Rhone Prodelta 17.4 11.6 4.0 5.5 4.1 nd 20.1 16.0 2.0 17.3 11.3 1.0 11.7 8.4 1.0 34.4 25.2 1.0
ndb 1.o nd nd
nd nd
28 4.0 nd 12 nd 47
Gulf of Lions
BC8 BC15 BC14 BC12 TY-3 TY-17 TY-19 TY-27
nd
0.1 nd 0.1 0.1 0.1 0.1 0.1
1.6 0.2 0.1
0.1 n d 0.1 n d 0.1 n d 0.2 0.1 0.1 0.1 0.1 0.1 0.1 0.2 0.2 0.4
28.5 11.2 34.3 30.8 24.5 39.4
1.o 1.8 2.2 2.1 2.0 1.5
0.4 1.o 1.5 2.4 2.0 0.5
1.5 7.7 1.1 2.0 2.7 5.1
0.5 1.3 1.5 0.6 0.4 0.2
0.3 0.6 0.2 nd 0.8 0.1 nd
1.o 1.7 1.1 nd 3.3 nd nd
2.9 5.3 2.1 5.6 7.3 1.o 0.5
43.1 19.5 4.2 12.1 20.7 0.5 0.1
27.2 47.0 7.6 38.5 27.9 0.2 0.09
4.0 7.5 1.8 18.8 9.1 0.4 0.1
Offshore Barcelona 6.5 4.5 6.5 0.5 0.4 0.6 0.6 0.3 0.1
6.9 0.2 nd
nd nd nd
39.5 1.7 1.9
14.6 1.8 0.4
8.7 0.5 2.0
2.9 0.4 0.6
Slope and Deep Basin 0.2 0.1 0.1 0.2 0.1 nd 0.3 0.2 nd 0.4 0.2 nd 0.2 0.1 nd 0.3 0.2 nd 0.4 0.2 nd 0.9 0.6 0.1
nd nd nd nd 0.1 0.1 0.1 0.1
nd nd nd nd 0.3 0.2 0.3 0.1
0.4 0.7 0.4 1.0 0.9 0.9 1.7 1.2
0.6 0.1 0 0.2 0.1 0.1 0.4 0.2
0.8 1.7 1.0 1.5 1.2 1.2 2.9 1.4
0.1 0.1 0.05 0.5 0.2 0.2 0.4 0.3
the highest correlation coefficient ($ > 0.83) for the Clophen A60 formulation, which might indicate that this is the most
widely used in the region. The 12 congeners analyzed in the present work represent ca. 55% of the composition of this mixture (20).However, qualitative and quantitative differenceswere observed among the individual congeners depending on the area. Such differences may be source related or may reflect the environmental fate of these pollutants, thus providing relevant information on their biogeochemistry in the basin. For a better assessment of these distributions, the study area was divided into five subareas, namely, the Rhone and Ebro prodeltas, offshore Barcelona, the Gulf of Lions, and the deep basin. The corresponding profiles are summarized in Figure 2. As it can be seen, the Ebro prodelta sediments are relatively enriched in the heptachloro-substituted components (Le., 180 and 1701,whereas in the Rhone area, the hexachlorinated congeners predominate (i.e., 153/132 and 138/158). This difference is likely related to a different composition of the PCB commercial mixtures most commonly used in Spain and France. Taking into account that the chlorination degree of these mixtures has been modified according to their period of production (3), it could well reflect a latter substitution from the market of highly chlorinated PCB formulations in Spain. In any case, these 1
513 32 106 167 31 227
0.4 0.1 nd nd 0.2 nd
1.1 3.1 1.3 4.9 3.9 0.2 0.1
Number of chlorines in the PCB congener are indicated in parentheses. 0.01 ngig for HCB).
2522
67 12 56 53 49 46
0.1 0.2 0.3 0.3 0.2 0.1
0.4 0.5 0.7 0.4 0.3 0.5
0.1 0.7 1.1 1.0 0.8 nd
Ebro Prodelta
4.5 0.4 0.3
63 13 67 70 43 97
HCB
ENVIRONMENTAL SCIENCE & TECHNOLOGY / VOL. 29, NO. 10.1995
14.7 9.1 1.5 5.8 6.1 0.3 0.1
nd, below the detection limit (ca. 0.05 ng/g for PCBs and DDTs, and
characteristic profiles may assist in recognizing the relative contribution of these two main PCB sources to the coastal sediments and particularly to the areas of deposition of riverine inputs. In this regard, it can be noticed that stations BC9, BC8, and D3 (Ebroslope); BC5 and 6; TY14 and 23 (in the Gulf of Lions) are little influenced by the river discharges accordingto the PCB patterns (Figure2). The concentration gradients in these zones indicate moreover a southwestern transport and deposition of PCBs (i.e., D1, D2 =. C1 > BC7 > B C l l > BC9). It is interesting to notice also that the stations closer to the river mouths, namely, RD5 and C1, exhibit lower concentrations of PCBs with respect to the farther ones. This feature has already been observed with other organic compounds (i.e., lipids) (21)and has been attributed to the lithology of sediments. In fact, Duinker (22)found a strong correlation between PCB concentrations and the contents of fine particles in sediments, which can be deposited farther offshore. Supporting evidence in the present case is the significant correlation between PCB concentrations in sediments and their TOC given in Table 1 ( r = 0.68, n = 28). A significant depletion of the most chlorinated congeners (Le., 180 and 170) was also found in going to the most remote sampling sites (i.e., BC12 and 14; TY3, 17, 19 and 27). This is illustrated in Figure 3 where the PCB distribu-
RH6NE PRODELTA
0.3
0.4 0.5 -
0.2
0.2
-
0.1
0.1
-
0.6
GULF OF LIONS
0.6
p
0.4
"
-
0-
n
4Cl
8CI
#Cl
7CI
4a .n23
I R W m R D 8 e R D 7 m R D 8 ORDlO
w
BCI
8CI
7CI
D B C 8 mBC4 a n 1 4 OBCS
0.7
BARCELONA TRANSECT
L
0.6
-
DEEP- BASIN
0.6
0.4 0.3 0.2 OS3l 0.2 0.1 0
0.6
0.6
8CI
7CI
8 CI
7 CI
4CI
0.7
-
EBRO PRODELTA 0.6
EBRO SLOPE
0.6
0.4
0.4
0.3 0.5 0.2
0.2
0.1
-
0.1
a
4CI
SCI
8CI
0
7u
I 4 CI 6 CI BBCO
lBC@ ODs FIGURE 2. Relative distribution of PCB congeners according- to chlorine substitution (4CI: 52; 5CI: 101,118 6CI: 149,153,132,138,158,128; 7CI: 187,'180, 170) in the different areas ofstudy. mBC7 h3Cl
6ecri
B D 1 OD2
tions of samples corresponding to transects offshore from I 1.8 , the Rhone and Ebro Rivers are reported. It is very unlikely, BC14 however, that the same arguments given above could be 1.6TY3 used to interpret these trends, so an alternative hypothesis 0 .-L0 must be considered. First, reductive dehalogenation of the 1.4TY17 BC8 0 highly chlorinated congeners that may occur under anoxic M8 0 areas containing high concentrations of PCBs (23,241is a AD7 0 2 1.2RD5 process presumably not relevant in the area because anoxic RDB 8 0 1conditions are only restricted to a few spots. On the other c1 hand, aerobic biodegradation under oxic conditions is more 0 effective for the less chlorinated compounds, giving rise to 0.8 I I I I I mixtures enriched in the more highly chlorinated congeners (23, which is not the case here. Second, gas-phase photolysis during the transport of the highly chlorinated congeners is also unlikely since aqueous and vapor-phase FIGURE 3. Ratios between the hexe- (Eof IUPAC Nos. 153,138, and oxidation of PCBs proceed via the addition of a hydroxyl 128) and hepta- (Eof IUPAC Nos. 187,180, and 170) substituted PCB radical onto the non-chlorine-substituted carbons (26'). congeners according to the distance of the stations from the coast.
u
,,
VOL. 29, NO. 10, 1995 / ENVIRONMENTAL SCIENCE &TECHNOLOGY 12523
~
TABLE 3
Selected Concentration Ratios of OC Compounds in Different Areas of Study DDEsttDDTs’ area of study
range
av
range
av
range
av
6 6 2 7 9
0.1-0.3 0.2-0.4 0.4-0.6 0.03-0.7 0.3-0.4
0.2 0.3 0.5 0.2 0.3
0.1-0.4 0.08-0.3 0.3-0.5 0.1-0.5 0.0-0.08
0.2 0.2 0.4 0.3 0.04
0.2-0.7 0.5-1.4 0.7-0.9 0.14-1.7 0.4-1.8
0.5 0.9 0.8 0.8 1 .o
Rhone prodelta Gulf of Lions
Barcelona offshore
Ebro prodelta slope and basin a
Sum of all DDD, DDE, and DDT isomers. Sum of congeners IUPAC Nos. 52, 101, 118
Third, and most likely, is atmospheric vapor-particle partitoning which may lead to a marine deposition enriched in the more volatile species (27). This is due to the fact that the less volatile and higher chlorinated PCBs are more easily removed from the atmosphere and cannot be transported to remote areas. Therefore, both in the atmosphere and in sediments from remote areas the more volatile PCBs dominate. Moreover, we have recently observed in the same region that lower chlorinated congeners are preferentially associated with sinking particles in the open sea (28).
Stations located in the Gulf of Lions (Le., BC4-6, TY14 and 23, in Figure 1) exhibited a similar or even higher depletion of the heptachloro-substituted congeners in comparison with the distributions found in the Rhone Estuary (Figure 2). This may also reflect a long-distance transport of PCBs rather than local sources. Sediments from offshore Barcelona showed an intermediate situation, probably indicating a contribution from multiple sources (e.g.,atmospheric deposition, sewage disposal, runoff, and river transport). In this respect, however, it should be noticed that the contribution of PCB in the NW Mediterranean from the sewage disposal via submarine outfalls is rather localized compared with the estuarine systems, as indicated by the samples collected in nearby Barcelona. In this case, despite the high levels found in the urban sewage sludge (291,their transport far away from the dumping site area is not easy to recognize. The PCB levels found in these sediment samples confirm that the northern part of the basin is the most heavily affected by these pollutants. In fact, the concentrations in the Rhone prodelta are 1 order of magnitude higher than in the Ebro (Table 2). Previous studies in the Mediterranean basin already pinpointed the Marseille Bay as one of the major contributors in the area (30). Effectively,the highest levelwas detectedinsediments fromstationRD11, showing the significance of this local pollution source (Le., Gulf of Fos)
Oryanochlorinated Pesticides Among this class of compounds, HCB,DDTs and their main metabolites, DDDs and DDEs, have been the major components identified. The spatial distribution of tDDTs is similar to that found for PCBs, with negative gradients in seaward transects. However, much higher concentrations of DDTs than PCBs were found in the river mouths. In this regard, the sampling site located in the Rhone mouth exhibited an extremely high concentration (RD5, 675 ngl g). These concentrations are from one to two orders of magnitude higher than those previously reported in the Mediterranean (11, 30, 311, and are only comparable to those obtained in heavily polluted locations (i.e. sewage 2524
PCBsb/tDDTsa
DDDs/tDDTsa
no. of samples
ENVIRONMENTAL SCIENCE &TECHNOLOGY / VOL. 29,
NO. 10, 1995
+ 149, 153 + 132, 138 + 158, 187, 128, 180, and 170.
disposal of Cortiou). In the Ebro prodelta, the highest concentration was also found in the river mouth (BC7,89 nglg). This is approximately one order of magnitude lower than in the Rhone prodelta. Sediments off Barcelona exhibited moderate concentrations (5-76 nglg), comparable to those of the Ebro prodelta (Table 2). Several ratios between tDDTs and its metabolites, namely, DDEs and DDDs, as well as PCBs were calculated (Table 3) in order to evaluate wether the DDT inputs are recent or not, and if the transport and deposition pathways of both types of pollutants are consistent. Since DDEsl tDDTs and DDDsltDDTs ratios are much lower than unity, it appears that recent inputs of DDT may still occur in the area, being particularly relevant in both estuaries. Sediments collected offshore Barcelona exhibited anomalously high DDEsltDDTs ratios, probably reflecting the impact of the primarytreated urban sewage effluent,whichis dumped northeast of stational. In fact, the DDT to DDE conversion occurs faster under the alkaline pH used in the wastewater treatment (32). Indeed, values as high as 115 nglg 4,4’DDE and DDEsltDDTsratios of 0.8were found in sediments collected near the sewage outfall (33). On the other hand, since the degradation pathway of DDTs in sediment is redox potential dependent, the DDDl DDE balance may indicate the prevalent depositional conditions in the area. While in oxic conditions, DDE is the main metabolite of DDT (32);in anoxic conditions, DDD is the major degradation product (34). Consequently, the higher DDDsltDDTs ratios found in coastal sediments (i.e., offshore Barcelona, Table 3) may reflect some low oxygenic conditions in shallow sediments receiving higher land-based organic inputs. Conversely, the lower values recorded in sediments collected in the slope and deep basin may be indicative of less reducing conditions or an extended degradation during the long-range transport of DDT. As far as the PCBslDDTs ratio is concerned (Table 31, it is interestingto notice that the higher values were obtained in coastal sediments off Barcelona that constitute a “hot spot” for PCBs, at remote stations (l.O), and in the Gulf of Lions (0.9).Conversely, the lowest values were recorded in both river estuaries. This could be interpreted on the basis of the different mechanisms of transport of these pollutants. While atmospheric deposition is probably the main route of introduction of PCBs in Mediterranean deepsea sediments, DDTs could mainly be river transported and, therefore, accumulated in river mouths by floculationl sedimentation of suspended particulate matter. This may also reflect the significance of agricultural activities undergoing in the respective river basins. Finally, HCB has been found widely distributed in the area (Table 2). The highest concentrations were found in the sampling sites located in front of the Gulf of Fos (RD11)
TABLE 4
Range of Fluxes of OC Compounds (Arithmetic Mean in Parentheses) in IUW Mediterranean Sediments (pg m-* year-') areas
PCBSO
PCBSm b
tDDTs
Rhone prodeltaC Ebro prodeltad Barcelona offs horee Gulf of Lionsf Ebro continental shelfg W. deep basinh E. deep basin' Ligurian Seaj
390-1340 (750) 24-157 (84) 5-101 4-10 (6.2)
810-2540 (1580) 50-280 (160) 8-168 8-20 (12)
620-6750 (2060) 40-290 (200) 5-122 4-12 (7)
110-290 (170) 4-70 (30) 0.4-5 0.1-1.3 (0.7)
1-80 (5) 1-2.6 (1.7) 0.1-0.4 (0.2) 2-9.3 (4.2)
2-17 (9) 2-5 (3) 0.3-0.8 (0.5) 6-25 (12)
2-5 (3) 1-2.3 (1.6) 0.2-0.5 (0.3) 0.8-2.2 (1.3)
0.1-0.3 (0.2) 0.1-0.3 (0.2) 0.01 -0.03 (0.02) 0.1-0.9 (0.4)
+
HCB
+
a Sum of congeners IUPAC Nos. 52, 101, 118 149, 153 132, 138 + 158, 187, 128, 180, and 170. bClophen A60 equivalents. CSamplingsites: RD5-8, 10, and 11. dSampling sites: BC7, 11; C1; D1 and D2. a Sampling sites: A1 and A2. Mean concentration values are not given. 'Sampling sites: TY8, 14, 23, and BC4-6. Sampling sites: BC8-9 and D3. Sampling sites: TY19 and 27; BClO and 12. Sampling sites: BC14-15 and TY3, 17. j Estimated from a sediment offshore Monaco (28). Q
and in the Rhone prodelta (RD5,7,and 8). This distribution is similar to that found for PCBs in the same area. In fact, a high correlation between PCBs and HCB concentrations in the whole area (r'= 0.918)has been obtained, suggesting a possible common source for both types of pollutants. As it is known, HCB is a byproduct of several industrial processes (35). In the Ebro prodelta, the concentrations were 1 order of magnitude lower and consistent with the riverine inputs already recognized and assessed (35).Urban sewage and atmospheric transport seem to be inputs of secondary importance in the basin, according to the levels found respectively in coastal sediments off Barcelona and in the remote sampling sites. Flux Measurements and Total Input Estimates. Using the sedimentation rates and sediment densities in the stations selected for study (18,19) and the concentrations of PCBs, DDTs, and HCB found in the sediment samples (Table 21, annual fluxes of deposition of the above compounds were calculated. The results, grouped in eight areas including stations with similar sedimentation rates, are summarized in Table 4. The highest fluxes for the different OC compounds examined were encountered in the area of influence of Rhone and Ebro Rivers, the former having a contribution about 1 order of magnitude higher than the latter. These results are higher than those reported for sinking particles collected with sediment traps moored at the continental slope of the Gulf of Lions (33,which could be accounted for by the different time scale between the flux measurements. On the other hand, the PCB fluxes corresponding to the open-sea sediments are comparable to those reported for the Sargasso Sea (3200 m) (381, indicating that remote areas of the Mediterranean behave like a rather pristine environment. As a first step for a mass balance calculation, the total input of OC compounds into deltaic sediments was estimated based on the mean surface areas previously defined (Table 5). These data provide a first-order estimate of the inputs of the major freshwater contributors in the Western Mediterranean. Taking into account the Rhone River concentration of total PCBs, Burns and Villeneuve (11)estimated an annual input of 3.6 and 0.2 t for particulate and dissolved phases, respectively. The present data are consistent with these estimates, because as indicated in Table 5 the annual input of PCBs onto the Rhone prodelta sediments is ca. 1.0 t. The results presented here for the Ebro prodelta, in the range of 140 and 112 kg of DDT and PCBs, respectively, per year are however 1 order of
TABLE 5
Annual Mass Incorporation of OC Compounds onto NW Mediterranean Sediments HCB
(Kd
PCBP (Kg/y)
tDDTs
areas of study
(Kdy)
(Kdy)
Rhone prodeltab Barcelona offshoreC Gulf of Lions and ProvenGal Coastd Ebro prodeltae Ebro shelf-slopef Catalan coast and Valencia Gulfs W. deep basinh E. deep basin' Ligurian Seaj
640 112 43 000
1000 19 516
1300 14 300
108 0.6 30
700 12 600 8 500
112 113 68
140 38 41
21 5 3
64 000 98 000 53 000
192 49 636
102 29 69
13 1.9 21
280552
2705
2033
203.5
surface
total
a Clophen A60 equivalents. Estimated from sampling sites RD58,10,11. EstimatedfromsamplingsiteAl. dEstimatedfromsampling sites TY8, 14, 23, and BC4-6. e Estimated from sampling sites: BC7, 11, and C1; D1 and D2. Estimated from sampling sites BC8-9 and D3. Q Estimated from sampling site A2. Estimated from sampling sites Ty-l9,27,and BC-l0,12. ' Estimatedfromsampling sites BC14-15and TY3, 17. Calculated from sediment trap data offshore Monaco.
magnitude higher than those reported for the river (36). This is probably accounted for by the variability of river inputs leading to biased river flux estimates. A pollutant load for the Ebro prodelta about 10 times lower than for the Rhone is consistent with allquantitative data previously presented and illustrated the relative contribution of these rivers to the land-based pollution budget of the basin. Fairly good agreement was also found for the inputs of HCB in the Ebro prodelta based on the concentrations of river waters (30-80 kglyear) (36). Early estimates by UNEP (39)of DDTs carried by runoff or through rivers in the NW Mediterranean basin were estimated as 5 t/year. Considering that the present calculated input onto sediments is of a few tons per year, those figures are probably overestimated. In any case, the values listed in Table 5 for PCB, DDTs, and HCB are the first ones based on field data covering the whole northwestern basin, and they point out that atmospheric deposition, mainly affectingthe deep-sea basin, should also be taken into account. Historical Trends. The selected sediment cores for assessing the historical trends of deposition of OC pollutants in the basin (BC4 and BC9) (Figure 1) showed almost VOL. 29, NO. 10, 1995 /ENVIRONMENTAL SCIENCE & TECHNOLOGY
2525
TABLE 6
Individual Concentrations (n& dry wt) of PCB Congeners, DDTs, and HCB through Sedimentary Recotd deposition period (subbottom depth, cm)
52
101 118a 153' 138'
187
128
180
170 2,4'-DDD 2,4'-DDE 2.4'-DDT 4.4-DDE 4 . 4 4 0 0 4,4-DDT HCB
1840-1880(30-22cm) ndb nd nd nd n d 1920-1940 (14-10cm) 0.21 0.25 0.58 0.61 0.75 1940-1960(10-6cm) 0.26 0.37 0.85 0.94 1.22 1960-1975 (6-3 cm) 0.38 0.29 1.25 1.24 1.56 1975-1990 (3-Ocm) 0.35 0.51 1.18 1.17 1.47
Rhone Prodelta (BC4) nd n d nd n d 0.15 0.27 0.12 0.53 0.28 nq 0.41 0.19 0.76 0.44 0.86 0.54 0.18 0.99 0.55 1.36 0.52 0.18 0.93 0.52 1.12
nd 0.18 0.54 0.25 0.23
nd 0.22 0.17 0.29 0.31
0.24 1.70 2.11 2.92 2.41
0.20 1.74 1.56 1.84 1.81
nqc 1.54 1.63 1.28 1.14
nd 0.8 1.1 1.5 1.4
1880-1920(22-14cm) nd nd 1920-1940 (14-10cm) 0.06 0.07 1940-1960 (10-6cm) 0.07 0.12 1960-1975 (6-3cm) 0.08 0.13 1975-1990 (3-Ocm) 0.10 0.21
Ebro Prodelta (BC9) nd nd nd nd nd 0.11 nd 0.14 0.10 0.15 0.20 n d 0.20 0.16 0.02 0.26 0.08 0.25 0.18 0.20 0.35 0.12 0.38 0.28 0.32
nd nd nd 0.05 0.09
nd nd nd 0.03 nd
0.08 0.38 0.61 0.73 2.02
0.06 0.32 0.37 0.31 0.40
nd 0.12 0.13 0.09 1.01
nd 0.1 0.1 0.3 0.4
a
nd 0.18 0.32 0.45 0.54
nd 0.19 0.34 0.42 0.56
nd 0.25 0.39 0.49 0.73
Coelution with congeners 149, 132, and 158, respectively. nd, below the detection limit (ca. 0.05 ng/g for individual PCB congeners and DDT,
0.01 for HCB). nq, unable to be quantified.
uniform 210Pbactivities in the upper layers (a few centimeters). At deeper horizons, the activities decreased exponentially, allowing the determination of an apparent or mean accumulation rate of 0.2 cm/year for both of them. The mixing rates (DB)were 6 and 2 cm21year,respectively, for BC4 and BC9, indicating that some vertical mixing in the former (DB > 3 cm2/year)could partially have destroyed its historical register. However, the nondimensional parameter G, which shows the correlation between the apparent (calculated below the surface mixed layer) and the real accumulation rate, exhibited values of 3.3 and 1.1, respectively for BC4 and BC9. G > 10 indicates the predominance of mixing over accumulation while G < 1 means a positive correlation between the apparent and the real accumulation rates. The dated cores were analyzed for PCBs, DDTs, and HCB (Table 6 ) . The concentration profiles through the sedimentary record exhibited a sharp decrease with depth, reaching to background levels at the 15-20-cm horizon corresponding to deposition dates ranging from 1880 to 1920. However, the concentration maxima were area and compound dependent. In fact, while the Ebro prodelta exhibited a maximum concentration of DDTs at the top horizon (0-3 cm) corresponding to 1975-1990, in the Rhone areathemaximumoccurredat3-6cm (1960-1975). These results are consistent with an earlier banning of DDT in France (1979)than in Spain (1986). PCB concentrations have remained constant since the 1960s in the Rhone area while in the Ebro they still increased during the last 15 years, despite the fact that regulations on PCB usage became simultaneously effective in both countries (1985). Organochlorinated compounds at low levels of concentration (0.01-0.41 nglg) were identified in both sediment cores at horizons corresponding to preindustrial (1840-1880) periods. Similar results have been reported by several authors (40-44). Sanders et al. (45) have addressed some of the possible causes of disturbance of sediment cores. Taking into consideration that procedural blanks were usually below 0.05 nglg, this occurrence could be attributed to bioturbation promoted by burrowing organisms and molecular diffusion. The agreement between theorethical and experimental distances at which a contaminant may migrate, calculated according to Wade and Quinn (46),is showing that molecular diffusion is feasible. Among the DDTs, 4,4'-DDE is the most abundant compound reflecting the prevailing oxic conditions in 2526
a
ENVIRONMENTAL SCIENCE &TECHNOLOGY / VOL. 29. NO. 10, 1995
TABLE 7
Fluxes of OC Compounds (ng cm-2 year-') through Sedimentary Record depositional period subbottom depth (cml PCBsa tDDTs 1840- 1880 1920- 1940 1940-1960 1960- 1975 1975- 1990 1880-1920 1920- 1940 1940- 1960 1960- 1975 1975- 1990 a
Rhone Prodelta (BC4) 30-22 ndb 14-10 1.2 10-6 1.7 6-3 2.1 3-0 1.9 Ebro Prodelta (BC9) 22-14 14-10 10-6 6-3 3-0
nd 0.5
0.8 1.0 1.4
HCB
0.1 1.1 1.2 1.3 1.1
nd 0.15 0.19 0.24 0.22
0.1 0.3 0.3 0.3 0.9
nd 0.02 0.03 0.06 0.10
Clophen A60 equivalents. nd, not determined.
surficial sediments. The significantly high degradation index (DDEsjtDDTs > 0.31) in the surficial horizons of some sediments is consistent with this assumption. However, the strong increase of the DDDsltDDTs ratio with depth (0.19,O-3 cm; 0.55,14-22 cm) in the Ebro core may indicate a lower prevalence of these conditions in the Ebro area. From the concentration data (Table 6), sedimentation rates, and sediment densities, fluxes of organochlorinated compounds in both areas of study were calculated (Table 7). In the surficial sediment horizons, fluxes in the Rhone prodelta were from 1.5to 2.0 times higher than in the Ebro, showing either a stabilization or a decrease in the former area since the early 1960%whereas in the latter they have almost doubled during the same period. It should be noticed, however, that due to the low sedimentation rate the time scale of these sediment core sections is rather large (15 years). Probably, a higher resolution time scale could allow the determination of whether or not there was a reduction in the input of OC compounds during the most recent years in the Ebro as well.
Acknowledgments Financial support was obtained from the STEP Program of the EEC under Project EROS-2000 (Contract EV4VO111F) and bythe SpanishPlan for Research (Grant NAT 93-0693). I.T. acknowledges a Ph.D. fellowship from the Catalan Education Ministry (Generalitat de Catalunya). Personnel
onboard RIV Marion Dufresne, RIV Garcia del Cid, and RIV Tyroare kindly acknowledgedfor their friendly atmosphere and assistance. E. Lipiatou kindly provided the Rhone prodelta samples. F. Broto (RamonLlull University)made available the software for the assessment of PCBs patterns from individual congeners.
Literature Cited (1) AlbaigCs, J., Ed. Environmental Analytical Chemistry of PCBs; Gordon and Breach: Reading, U.K., 1994; p 403. (2) De Voogt, P.; Brinkman, U. A. Th. In Halogenated biphenyls,
terphenyls, naphthalenes, dibenzodioxins and related products, 4th ed.; Kimbrough, R. D., Jensen, A. A., Eds.; Elsevier: Amsterdam, 1989; pp 3-69. (3) Ballschmiter, K.; Wittlinger, R. Enuiron. Sci. Technol. 1991, 25, 1103-1 11 1. (4) Iwata, H.; Tanabe, S.; Sakai, N.; Tatsukawa, R. Enuiron. Sci. Technol. 1993, 27, 1080-1098. (5) Cotham, W. E.; Bidleman, T. F. Chemosphere 1991,22, 165-188. (6) Geyer, H.; Freitag, D.; Korte, F. Ecotoxicol. Enuiron. Sat 1984, 8, 129-151. (7) Fowler, S. In PCBs and the environment The Mediterranean Ecosystem; Waid, J. S., Ed.; CRC: Boca Raton, FL, 1989; Vol. 111, p 209. (8) UNEPIFAOIWHOIIAEA.Assessment of the state of pollution of
theMediterranean by organohlogen compounds; MAPTechnical Report Series 39; UNEP: Athens, 1990; p 224. (9) ECETOC. Concentrations of industrial organic chemicals measured in the environment: the influence of physico-chemical properties, tonnage and use pattern. Technical Report 29; European Chemical Industry Ecology and Toxicology Centre: Brussels, 1988. (10) Marchand, M.; Caprais, J. C.; Pignet, P. Mar. Environ. Res. 1988, 25, 131-159. (11) Burns, K. A.; Villeneuve, J.-P. Mar. Chem. 1987, 20, 337-359. (12) Tolosa, I.; Readman, J. W.; Fowler, S. W.; Villeneuve,J. P.; Bayona,
J. M.; Albaigbs, J. Deep Sea Res., submitted for publication. (13) Duinker, J. C.; Schultz, D. E.; Petrick, G. Mar. Pollut. Bull. 1988, 19, 19-24. (14) Schulz, D. E.; Petrick, G.; Duinker, J. C. Enuiron. Sci. Technol. 1989, 23, 852-859. Valls M.; Bayona J. M.; AlbaigCs J. Int. 1. Environ. Anal. Chem. 1990, 39, 329-348. (15) Eganhouse, R. P.; Gosset, R. W. Anal. Chem. 1991, 63, 21302137. (16) Millot, C. Oceanol. Acta 1987, 10, 143-148. (17) Valls, M.; Bayona, J. M.; AlbaigCs, J. Int. 1. Enuiron. Anal. Chem. 1990, 39, 329-348. (18) Zuo, 2.; Eisma, D.; Berger, W. Oceanol. Acta 1991, 14,253-262. (19) Zuo, Z.; Eisma, D.; Gieles,R. In WaterPollutionResearch Reports; No. 28; Martin, J.-M., Barth, H., Eds.; Commission of the European Communities: Belgium, 1991; pp 425-436. (20) Duinker, J. C.; Hillebrand, M. T. J. Enuiron. Sci. Technol. 1983, 17, 449-456. (21) Grimalt, J. 0.; Albaiges, J. Mar. Geol. 1990, 95, 207-224. (22) Duinker, J. C. Neth. 1. Sea Res. 1986, 20, 229-238.
(23) Quensen, I. F.; Tiedje, J. M.; Boyd, S. A. Science 1988,242,752754. (24) Rhee, G.-Y.; Sokol, R. C.; Bethoney, C. M.; Bush, B. Enuiron. Sci. Technol. 1993, 27, 1190-1192. (25) Fava, F.; Zappoli, S.;Marchetti, L.; Morselli,L. Chemosphere 1991, 22, 3-14. (26) Sedlak, D. L.; Andren, A. W. Enuiron. Sci. Technol. 1991, 25, 1419-1427. (27) Bidlernan, T. F. pnuiron. Sci. Technol. 1988, 22, 361-368. (28) Tolosa, I. Ph.D. Dissertation, University of Barcelona, Barcelona, Spain, 1993, pp 449. (29) Bayona, 7. M.; Ferntindez, P.; Porte, C.; Tolosa, I.; Valls, M.; AlbaigCs, J. Chemosphere 1991, 23, 313-326. (30) Amow, A:; Blanc, A.; Jorajuria, A.; Monod, J. L.; Tatossian, J. Ves Journbes Etude Pollutions; CIESM Reports: Cagliari, 1981; pp 459-470. (31) Marchand, M.; Caprais, J. C.; Cosson-Mannevy, M. A,; Moriniere, P. Oceanol. Acta 1983, 6, 269-282. (32) Wolfe, N. L.; Zepp, R. G.; Paris, D. F.; Baughman, G. L.; Hollis, R. C. Enuiron. Sci. Technol. 1977, 11, 1077-1081. (33) Fernttndez, P. Ph.D. Dissertation, University of Barcelona, Barcelona, Spain, 1991, p 405. (34) Zoro, J. A.; Hunter, J. M.;'Eglinton, G.; Ware, G. C. Nature 1974, 247, 235-247. (35) Tobin, P. In Hexachlorobenzene: Proceedingsofan International Symposium; Moms, C. R., Cabral, P. R., Eds.: International Agency for Research on Cancer: Lyon, France, pp 3-1 1 . (36) Cid, J. F.; Risebrough, R. W.; De Lappe, B. W.; Maritio, M. G.; Albaigks, J. Mar. Pollut. Bull. 1990, 21, 518-523. (37) Fowler, S. W.; Ballestra, S.; Villeneuve, 1. P. Conr. ShelfRes. 1990, 29, 1005-1023. (38) Knap,A. H.; Binkley, K. S.; Deuser, W. G. Yarure 1986,319,572574. (39) UNEP/ECElUNIDO/FAOIUNESCOl\VHO/IAEA. UNEP Regional Seas Reports and Studies No 32. UNEP: Geneva, 1984; p 97. (40) Venkatesan, M. I.; Brenner, R'. S.; Turh, E.; Bonilla, J.; Kaplan. I. R. Geochim. Cosmochim. Acta 1980, 44, 789-802. (41) Buchen, H.; Bihler, S.; Schotr, P.; Roper, H. P.: Pachru, H.-I.; Ballschmirter, K. Chemosphere 1981, 10, 945-956. (42) Burns, K. A,; Villeneuve,A. Geochim. Cosmochim. .4cra 1983,47, 995-1006. (43) Rapaport, R. A.; Urban, N. R.; Capel, P. D; Baker, J. E.; Looney, B. B.: Eisenreich, S. J.; Gorham, E. Chemosphere 1985, 14, 11671173. (44) Eisenreich, S. 1.; Capel, P. D.; Robbins, J. A,; Bourbonniere, R. Environ. Sci. Technol. 1989, 23, 11 16- 1126. (45) Sanders, G.; Jones,K. C.; Hamilton-Taylor,J. Enuiron. Sci. Technol. 1992, 26, 1815-1821. (46) Wade, T. L.; Quinn, J. G. Org. Geochem. 1979, 1 . 157-167.
Received for review December 12, 1994. Revised manuscript received June 8, 1995. Accepted June 12, 1995.@ ES9407507 @Abstractpublished in Advance ACS Abstracts, July 15, 1995.
VOL. 29, NO. 10, 1995 /ENVIRONMENTAL SCIENCE &TECHNOLOGY
2527
