l
l
l
l
l
l
l
l
l
l
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l
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-
B///J&/-02 u a
TEMPERATURE (‘C)
Figure 9. Percent oxidation to FepOBvs. temperature 0 FeO (Bioclinical Labs, Tyler 200/400); 0 pyrite (Rico, Colorado, Tyler 200/400); A Fe304 (D. R . Goldsmith Metal Corp., >5 w). Heating rates are 10 ‘Clmin for FeO and 20 ‘C/min for FeoO, and pyrite
not done so. The conclusion from this experiment is that all the iron compounds being considered are oxidized into FepOs rapidly, and it subsequently catalyzes the sulfation of CaO in the manner already discussed. Acknowledgment
We thank Andrej Macek of the U S . Energy Research and Development Administration for his helpful suggestions and discussions. Paul T. Cunningham, Albert A. Jonke, William M. Swift, and Gerhard G. Vogel of Argonne National Laboratory and James W. Sutherland of Brookhaven are also thanked for helpful discussions.
Literature C i t e d (1) Nack, H., Kiang, K. D., Liu, K. T., Murthy, K. S., Smithson, G. R., Jr., Oxley, J. H., “Fluidized Bed Combustion Review”, in
“Fluidization Technology”, D. L. Keairns, Ed., Vol 11, Hemisphere Publ., Wash., 1976. (2) Jonke, A. A., in “Fluidized Bed Combustion”, Proc. 4th Int. Conf., p 13, MITRE Corp., McLean, Va., 1976. (3) Ehrlich, S., ibid., p 15. (4) Borgwardt, R. H., Environ. Sci. Technol., 4,59 (1970). (5) Jonke, A. A., et al., “Reduction of Atmospheric Pollution by the Application of Fluidized-Bed Combustion”, Annual Rep. ANL/ ES-CEN-1004,1971. (6) Hoy, H. R., Roberts, A. G., AIChE Symp. Ser., 68 (126), 225 (1972). (7) Squires, A. M., Virginia Polytechnic Institute and State Univ., Blacksburg, Va., private communication, 1976. (8) Yang, R. T., Cunningham, P. T., Wilson, W. I., Johnson, S. A., Adu. Chem. Ser., 137,149 (1975). (9) Snyder, R. B., Wilson, W. I., Vogel, G. J., Jonke, A. A., “Fluidized Bed Combustion”, Proc. 4th Int. Conf., p 439, MITRE Corp., McLean, Va., 1976. (10) Harrington, R. E., Borgwardt, R. H., Potter, A. E., Am. Ind. Hyg. Assoc. J., 29,52 (1958). (11) Ehrlich, S., patent disclosure cited in Gasner (1977), 1968. (12) Gasner, L. L., Proc. Fluidized Bed Combustion Tech. Exch. Workshop, Vol 11, p 283, MITRE Corp., McLean, Va., 1977. (13) Vogel, G. J., et al., “Supportive Studies in Fluidized-Bed Combustion”, Quarterly Rep., ANL/ES-CEN-1018, 1976. (14) Vogel, G. J., et al., ibid., ANL/ES-CEN-1019,1977. (15) Ashmore, P. G., “Catalysis and Inhibition of Chemical Reactions”, Butterworths, London, England, 1963. (16) Boreskov, G. K., Sokolova, T. I., J . Phys. Chem. USSR, 18.87 (1944); Chem. Abstr., 41,2043 (1947). (17) Kawaguchi, T . , J . Chem. SOC.Jpn., 76,1112 (1955). (18) Wendlandt, W. W., “Thermal Methods of Analysis”, 2nd ed., Wiley-Interscience, New York, N.Y., 1974. (19) Yang, R. T., Chen, J. M., unpublished results, Brookhaven National Lab, 1978.
Received for review November 3, 1977. Accepted January 30,1978. Work performed under the auspices of the Division of Materials and Exploratory Research, U.S. Department of Energy, under contract EY-76-C-02-0016, Washington, D.C. 20545.
Behavior and Transport of Mercury in River-Reservoir System Downstream of Inactive Chloralkali Plant Ralph R. Turner’ and Steven E. Lindberg Environmental Sciences Division, Oak Ridge National Laboratory,Oak Ridge, Tenn. 37830
w Aquatic losses of mercury from a chloralkali plant closed in 1972 continue to cause elevated levels of mercury in downstream water, suspended matter, and bottom sediment. These losses are attributed to leaching of soluble mercury in solid wastes located a t the site and have recently amounted to -39 kglyr. Concentrations of mercury in water and suspended matter immediately downstream of the plant site are typically 20 times higher than immediately upstream. The silt-clay fraction of bottom sediment immediately downstream of the plant site contains up to 200 times as much mercury as similar sediments collected immediately upstream. Field observations and application of a simple dilution model indicate that rapid decreases in mercury concentrations in water as a function of distance below the plant site could be accounted for partially by dilution, although up to 60% of the observed decreases are apparently related to nondilution processes. An environmentally important trend in the chloralkali industry has been steady progress toward complete elimination of the discharge of mercury to waterways. Despite these reductions in mercury discharges, natural recovery of impacted 918
Environmental Science & Technology
aquatic ecosystems has been neither rapid nor complete, largely because leaking industrial waste deposits and contaminated bottom sediments from former unregulated operations persist (1-6). This paper describes our research on the distribution of mercury in a river-reservoir system that continues to receive effluents from an inactive chloralkali plant. Objectives were to determine the magnitude of current losses of mercury from residual waste deposits, the distribution of mercury downstream of these wastes, and the processes regulating these distributions. Additional details related to this work can be found in Van Hook et al. (7). Study Site. The former site of the chemical manufacturing complex, which included a chloralkali (mercury cell process) and ammonia soda plant, is in southwestern Virgina on the banks of the North Fork of the Holston River (NFHR). The NFHR is a fast-flowing mountain stream that originates -77 km above the former plant site and flows 133 km southwest through a rural landscape to the confluence with the South Fork of the Holston River at Kingsport, Tenn. Thence, the main Holston River flows 50 km into Cherokee Lake, a 1 2 260-ha reservoir created in 1942 by the Tennessee Valley Authority. The NFHR is characterized over most of its length by a coarse rocky substrate with extensive riffle and pool areas. 0013-936X/78/0912-0918$01.00/0
@ 1978 American Chemical Society
Mean daily discharge upstream from the former plant site is 8.5 m3/s (drainage area = 575 km2). Downstream near the confluence with the South Fork, the mean daily discharge is 25.4 m3/s (drainage area = 1740 km2) (8). A t the plant site two large (44 ha) unlined settling ponds were used for clarification of waste slurries from the ammonia soda, caustic soda, and chlorine processes, the ammonia soda plant contributing by far the largest amount of solid waste. The chlorine plant, which was built in 1952 with an annual design capacity of 81 000 metric tons ( 9 ) ,was closed in June 1972. The settling ponds are situated immediately adjacent to the NFHR behind steep dikes composed of boiler ash and CaC03 waste. The total volume of solid waste in the settling ponds is estimated by us to be -6 X 106 m3. The location of the ponds perched above the NFHR and on the flank of an adjacent ridge favors leaching of soluble waste components by direct rainfall and by runoff from the ridge. The ponds are drained from the surface and at intermediate depths by stop-log structures, while clay, iron, and plastic pipe provide drainage through the toe of the dike directly into the river. Methods a n d Materials. The results reported here are based on samples collected between February 1975 and January 1976. Sampling locations along the river-reservoir system are designated herein as river kilometers (RK) above or below the chloralkali plant site. Collection, handling, and analytical procedures for water samples are fully outlined elsewhere ( 7 ) and basically followed published methods (IO-1.2). Sediments were collected by hand, Ekman dredge, or piston coring, depending on water depth and on the type of sample desired. To maintain textural uniformity and thus minimize particle size effects on mercury concentration (13,14), only silty and clayey sediments were collected. In the few cases where such biased collection was unsuccessful, the coarser material (>44-p diameter) was removed from the bulk sediment by wet sieving prior to analysis for mercury. Digestion of sediment and waste solids followed the procedure given by Feldman ( 1 1 ) . Cesium-137 activity in lake sediment was determined using nondestructive gamma ray spectrometry (15, 16).
Results and Discussion Source Area Studies. Chemical analysis and x-ray diffraction of the solid waste remaining at the plant site indicated the elemental composition to be primarily Ca, C1, Mg, and Na, the predominant crystalline phase being calcite. The natural leachate from the settling ponds was a caustic (pH 12) brine composed primarily of chlorides and hydroxides of sodium and calcium. Total mercury content of the solid waste collected in a single 2-m core from one of the settling ponds was highly variable as a function of depth (ranging from 4.4 to 350 pg/g). However, the mean mercury concentration in the upper 1 m of this core (198 f 78 pg/g) was significantly (t-test, p I0.001) higher than the mean for the lower 1m (51 f 38 bg/g). If this distribution is representative of the settling ponds as a whole, it may reflect increased use of the settling ponds for disposal of mercury-containing wastes in the final years of plant operation. Attempts to identify the chemical form of mercury in the solid waste were inconclusive. However, the volatility of waste-associated mercury as a function of temperature reported by us elsewhere ( I 7) suggested that mercury exists in the waste at least partially as the elemental species. In addition, batch extractions of the solid waste, using natural rainwater with a pH of 3.8,indicated that less than 5% of the whole waste and less than 2% of the total mercury in the waste were soluble. Total mercury concentrations observed in pipe outfalls and seepage from the two settling ponds (pond 1leachate, = 68
-
x
pg H g L , range = 11-230 pug Hg/L, N = 15; pond 2 leachate, = 1.8pg H g L , range = 0.1-7.4 pg Hg/L, N = 8) indicated that only one of the ponds was a major source of mercury, and that the highest mercury flux (8-50 g/day) was associated with one pipe outfall that received water from both the pond surface and subsurface seepage. According to thermodynamic equilibria considerations ( 1 8 , 1 9 ) ,the high pH and the chloride content of the leachate strongly favor existence of dissolved mercury in the leachate as hydroxy- and chloro-complexes (e.g., Hg(0H); or HgCli-) as well as dissolved Hg'. The aquatic flux of mercury from the settling ponds into the adjacent river via seepages and overflow structures (pipe outfalls) has been previously estimated by us using direct measurements and mass balance calculations ( I 7 ) . Depending on the antecedent conditions and quantity of most recent rainfall, the net flux of mercury from the disposal site via aquatic pathways varied from 26 to 350 g/day, the higher fluxes being associated with stormflow conditions. By comparison, on one day while the plant was still in operation (August 12, 1970), the flux of mercury into the river was reported (20)to be 260 g/day. For the period October 1973 to September 1974 the estimated annual aquatic flux of mercury from the disposal site was 39 f 2 kg (predicted sum f estimated standard error of the sum of predicted fluxes) ( 1 7 ) . The minimum quantity of mercury remaining in the waste pond system can be estimated using the limited core data from 100 pg/g Hg in solid waste of one of the waste ponds pond 1).An estimate of the total mercury burden of the upper 2 m of this pond can thus be calculated using the surface area of this pond, 2.9 X l o 5 m2 (66% of total surface area of both ponds), and assuming a waste density of 2.0 g/cm". If the mercury content of this mass indeed averages 100 pg/g, then the total mercury burden of the upper 2 m of this pond is -9 x 104 kg. Calculations ( 7 ) using this quantity and the annual flux of mercury from the waste pond indicated the potential persistence of the mercury problem on the NFHR in the absence af abatement measures. Distribution a n d Behavior of M e r c u r y in River System. Total mercury concentrations measured in river water immediately downstream of the plant site averaged 0.15 pg/L during the study period (Table I), while total mercury concentrations immediately upstream averaged 0.008 pg/L. Essentially all the mercury in river water upstream of the plant site was in particulate form, but about one-third (33 f 16%) of the mercury immediately downstream occurred in dissolved form. This is consistent with the solubility of the mercury in
x
(x-
Table 1. Mean (2) and Standard Deviation (SD) of Mercury Concentration in Water, Suspended Matter, and Bed Sediment Immediately Upstream and Downstream of Former Chloralkali Plant Site During Study Period Total Hg (MIL)
X
SD N
-
Water Dlssolved Hg (MIL)
Suspended matter Hg a (Mm
Upstream -2.7 km 0.008 0.004 10
0.05). However, the plot of these variables (Figure 1)suggests that the relationship is not linear. Significantly, mercury concentrations on suspended matter increased systematically with decreasing stream discharge during the falling stage of a storm hydrograph, Le., with increasing relative influence of the point source of mercury (Figure 1). Variations in mercury conceptrations in water, suspended matter, and bottom sediment over more than 250 km of the NFHR and its receiving waters are illustrated in Figure 2. The location of the former chloralkali plant a t river kilometer 0 (RK 0) is conspicuous by the peak concentrations of mercury observed immediately downstream of the plant site. Concentrations decrease rapidly downstream from the plant site to about RK 40, below which concentrations vary only slightly. Except as indicated, the data plotted in Figure 2 represent results of a single synoptic (August 1975) survey of mercury in the river-reservoir system. As noted in Table I for the river stations immediately upstream and immediately downstream of the plant site, there was considerable temporal variability in concentrations at most stations. Bottom sediments should, to some extent, integrate the variability in water and suspended matter concentrations and thus may reflect average conditions at a given station. Thus, by way of comparison, we have included in Figure 2c bottom sediment data from an earlier (1973-74) study of mercury in this river system (5).In general, these distributions of mercury in bottom sediment as a function of river kilometer are similar.
(x
920
Environmental Science 8 Technology
(x
1
I
-jZo E 16
e
I
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I
.
A
1
I FALLING LIMB OF STORM HYDROGRAPH JANUARY 4976
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4-
+
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. I
.
MERCURY ON SUSPENDED MATTER ( p g Hg/g)
Figure 1. Relationship between NFHR discharge and Hg concentrations on river suspended matter at 3.1-6.4 km below plant site Solid circles: samples collected May-August 1975
0
JULY-AUGUST 4975
-
a DATA FROM REFERENCE 5
BRACKETS INDICATE RANGES
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-
-20
0
40 80 420 $60 200 240 RIVER KILOMETER ABOVE 1-1 AND BELOW CHLORALKALI PLANT SITE
280
Figure 2. Downstream distribution of dissolved and total Hg in river water column (a), total Hg on river suspended matter (b), and total Hg in silt-clay fraction of river bottom sediments (c)
However, our observations of bottom sediment mercury concentrations below the chloralkali plant are somewhat lower than those reported earlier, perhaps reflecting a gradual flushing of the more highly mercury contaminated sediments from the river system since plant closing. It would seem desirable to confirm this possibility with a follow-up sampling. Dilution Model for Total Mercury in Water. The downstream distribution of total mercury in water lends itself to the application of a simple dilution model because the plant site represents a strong point source of mercury to the NFHR. The concentration of total mercury in water downstream of the source should be regulated primarily by dilution, sedimentation, vapor exchange with the atmosphere, and exchange with bottom sediments. All of these processes are normally expected to result in a downstream reduction in mercury concentration. We have sufficient information to quantitatively evaluate only the effect of dilution. Given an assumption of steady-state conditions, including constant source strength, a time-invariant downstream transport rate, and complete physical mixing, the effect of dilution on mercury concentration at any downstream point can be estimated using the relative increase in drainage area as an index of the increase in streamflow rate a t that point. Assumption of steady-state conditions is probably justified only over short periods of time (on the order of days) when streamflow and source strength are not rapidly changing. If only dilution is operative, the concentration of mercury, C, expected a t a downstream point with drainage area, A , will be
cantly, the best agreement between the dilution model and field observations occurred for the observation period with the highest stream discharge (Figure 3, top), suggesting that the relative importance of processes other than dilution is dependent on flow conditions. T o the extent that the travel time of a discrete water parcel between two points along the river is reduced a t higher stream discharge (when dispersion is greatest), opportunities for losses of mercury from a water parcel by sedimentation, and other time-dependent processes will also be reduced. Thus, the dilution model should indeed predict downstream mercury concentrations more successfully a t higher stream discharge than a t low discharge. Distribution of Mercury in Reservoir Sediments. Association of mercury downstream of the chloralkali plant site predominantly with river suspended matter suggested that the large impoundment of the Holston River below RK 188, Le., Cherokee Lake, has been and continues to be a major sedimentary sink for mercury. Mercury in the silt-clay fraction of the surficial sediments of this lake ranged from 0.47 to 2.40 pg/g with the highest concentration near the input of the Holston River and the lowest concentration near the lake
0.44
--
0.10
I
0 = 26.7 m3/sec
a
I
0
._ -
23.
where A, is the drainage area a t a well-mixed point below the source, C, is the mercury concentration a t A,, and C b is the regional background concentration of mercury (taken here to be 0.008 pg/L, see Table I). Basically the equation states that mercury concentration decreases downstream of a strong point source as a function of the increase in drainage area and the concentration of mercury in the uncontaminated tributaries which account for the drainage area increase. The equation is derived from simple mass balance considerations such as outlined by O'Connor (24) and should only be applied if streamflow rate is directly proportional to drainage area. Hydrologic data (8) for the two stream gauging stations (at RK -2.7 and RK 119)on the NFHR where the drainage areas are 575 and 1740 km2 indicate that average daily stream discharge a t these stations differs by a factor (2.99), which is nearly equal to the ratio of the drainage areas (3.03). Thus, between RK -2.7 and RK 119 the above equation appears to be applicable. Using the relationship between drainage area and river kilometer along with mercury concentrations observed immediately below the plant site on five different occasions (three from earlier studies, ref. 5 ) , we calculated mercury concentrations expected downstream of the plant due to dilution. Comparison of the observed and expected concentrations of total Hg as a function of distance from the point source (illustrated in Figure 3 for two representative cases, one high flow and one low) reveals that a significant fraction (Le., >40%) of the initial rapid downstream decrease in mercury concentrations can be accounted for by dilution alone. The model does not predict a uniform change in concentration as a function of distance downstream due to the stepwise increase in drainage area a t each confluence of a tributary with the NFHR. Contributions from three tributaries within 20 km of the plant site increase the drainage area, and thus streamflow, by a factor of 1.3. Mercury concentrations observed 20 km below the plant site decreased by a factor which varied between 1.3 (Figure 3, top) and 3.1 (Figure 3, bottom). Signifi-
I
0,
I J
0.06
2 0 b-
0.02
- 20
20
60 RIVER k m
100
140
Figure 3. Comparison of expected concentrations of total Hg in downstream water calculated from application of dilution model with field observations under high and low stream discharge (Q) conditions
Volume 12,Number 8, August 1978 921
outflow. Thus, the decreasing gradient in mercury concentration in river surface sediments that characterized the environment below the former plant site was continued through the lake. To establish the natural background mercury concentration expected in the lake sediment, additional sediment samples were collected in two semi-isolated coves of the lake receiving sediment predominantly from adjacent, unimpacted, tributary streams. The silt-clay fraction of these sediments contained 0.14-0.29 pg Hg/g, or about one-fifth the levels observed in midlake sediments of comparable particle size and about the same levels as those found in the silt-clay fraction of river sediments upstream of the former plant site on the NFHR. Shacklette et al. (25) give 0.147 pg Hg/g as the average mercury concentration in uncontaminated soils and other surficial materials from the eastern conterminous United States. Thus, in the absence of anthropogenic inputs of mercury to Cherokee Lake, we might expect that sediment levels should not exceed about 0.15 pg Hg/g, except where high content of organic matter (26-28) may be a factor. Mercury distributions in clayey sediment cores from each end (RK 230 and RK 277) of Cherokee Lake suggested that the anthropogenic mercury loading of the lake has varied considerably with time (Figure 4). Although the cores came from areas of the lake that contrasted considerably in water depth and proximity to the major river input, the mercury concentration profiles have some similar features, i.e., the occurrence of highest concentrations a t 20-35 cm below the present (1976) sediment surface and a decreasing trend in mercury concentration in the most recently deposited sediments. Cesium-137 activity profiles were used as approximate guides to the chronology of sediment deposition (15,16);the peak atmospheric fallout and hence lake deposition of 137Cs occurred in 1963 (29). A well-defined peak in 137Csactivity occurred in only one core, that from RK 277, and thus provides the only chronology of sedimentation. Occurrence of the peak 137Cs activity a t 20-25 cm in the core from RK 277 indicates that deposition of this layer occurred ca. 1963 and yields an average rate of sedimentation since 1963 of -1.9 cm/yr. Extrapolating this rate over the total thickness (-50 cm) of sediment a t RK 277 yields a date for the deposition of the oldest sediments that is prior to the existence of the chloralkali plant on the NFHR. Significantly, these early sediments contained only natural background levels of mercury. Applying the estimated rate of sedimentation to the mercury profile in the core from RK 277 and assuming no significant postdepositional redistribution (e.g., by diffusion, physical mixing) of sediment-bound mercury, and a constant yearly rate of sedimentation, indicates that the peak concentration of mercury occurred ca. 1958. However, the 5-cm subsampling interval obviously imposes a 2- to 3-year uncertainty in this date. We have no explanation as to why mercury deposition a t RK 277 should have been higher in the late
0.4
0
12
0.8
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1
2
3
4
5
6
7
8
0 10
20 30 40
c
4
50 60
CORE FROM R K 2 7 7
C O R E FROM R K 2 3 0
Figure 4. Distribution of total Hg and 13'Cs in sediment cores from midlake (RK 230) and terminus (RK 277) of Cherokee Lake 922
Environmental Science & Technology
1950's than during other times, unless early operations of the chloralkali plant were especially inefficient with respect to aquatic losses of mercury. The mercury and 137Csprofiles in the core from RK 230 are difficult to interpret. The trend of increasing 137Csactivity with depth in the core and the peak in 137Csactivity toward the bottom (at 40-45 cm) suggests that the 60-cm core was of insufficient length to penetrate completely through sediments deposited during the period of maximum l37Cs fallout (1959-1963) (29). This suggestion is consistent with an expected higher rate of sedimentation nearer the Holston River input to the lake. The average sedimentation rate a t RK 230 would thus need to be equal to about 3.5 cm/yr to account for the burial of the 1963 layer by 4 0 4 5 cm of sediment. This rate of sedimentation, if uniform since 1963, suggests that the peak mercury layer a t 20-25 cm was deposited ca. 1970 and is thus unrelated chronologically to the peak in the core from RK 277. Regardless of the precise date of deposition of the high mercury layer a t the 20-25-cm level, this peak must have occurred near the end of operations a t the chloralkali plant since there has been a steady rapid postpeak decrease (8.1-2.4 pg Hg/g) in concentration, and concentrations below the peak (3.6-4.2 pg Hg/g) are consistently above background levels for this area.
Summary Mercury continues to leach from solid wastes from a chloralkali plant closed in 1972 after 20 years of operation. The wastes occupy about 6 X 106 m3 and are contained within two settling ponds covering 44 ha immediately adjacent to the North Fork of the Holston River in Southwestern Virginia. Total mercury concentrations in solid waste from the settling ponds were highly variable as a function depth, ranging from 4.4 to 350 pg/g in one 2-m core. However, less than 2% of this mercury was readily soluble. Mercury in natural leachate from the ponds ranged from 0.1 to 230 pg/L and probably exists in the leachate as hydroxy- and chloro-complexes as well as dissolved elemental mercury. The aquatic flux of mercury from the settling ponds into the adjacent river via numerous seepages ranged from 26 to 350 g/day and was estimated recently to amount to -39 kg/yr. Concentrations of mercury in water (0.15 f 0.05 pg/L) and suspended matter (7.6 f 3.8 pg/L) immediately downstream of the plant site were typically 20 times higher than those immediately upstream. The silt-clay fraction of bottom sediment immediately downstream of the plant site contained up to 200 times as much mercury (19.3 f 1.3 pg/g) as similar sediments collected immediately upstream. Variations in mercury concentrations in water, suspended matter, and bottom sediment over more than 250 km of the downstream river-reservoir system indicated rapid decreases to a point -40 km below the plant site followed by only slight variations. Field observations and application of a simple dilution model indicated that the rapid decreases in total mercury concentrations in water as a function of distance below the plant site could be partially accounted for by dilution. However, up to 60% of the observed decreases were apparently related to nondilution processes. Because the dilution model most successfully predicted downstream mercury concentrations a t higher stream discharge, it was concluded that nondilution processes were more important a t low stream discharge. Mercury in the silt-clay fraction of the surficial sediments of a large downstream impoundment, which appears to have been an important sink for mercury discharged during plant operation, ranged from 0.47 to 2.40 pg/g. Background levels of mercury expected in sediments from this impoundment in the absence of anthropogenic inputs were estimated to be -0.15 pg/g. Mercury profiles in sediment cores from this impoundment suggest that mercury input has been decreasing
with time since the chloralkali plant was closed. The chronology of mercury deposition in the impoundment inferred ~ profiles in the cores suggested that mercury from 1 3 T Cactivity input to the impoundment was highest during early operations of the upstream chloralkali plant and perhaps again near the end of operations. Overall results of this study substantiated that recovery of a river-reservoir system formerly subjected to high discharges of mercury by a chloralkali plant has been very slow and is far from complete. Continued losses of mercury from mercurycontaminated solid wastes stored a t the plant site are implicated in this slow recovery. Acknowledgment
J. R. Lund provided analytical support; D. Klein and S.E. Herbes critically reviewed the manuscript. Literature (1) Nakanishi, J., “The Cause and Channels of Mercury Pollution
in Western Ontario”, Appendix I in: Buffa, L., Report E P S 3WP-76-7, pp 43-52, Environment Canada, 1976. ( 2 ) Armstrong, F.A.J., Hamilton, A. L., in “Trace Metals and Metal-Organic Interactions”, P . C. Sinaer, Ed.. DU 131-55. 1974. (3) Annett,C. S.,D’Itri, F. M., Ford, J. R.;Prince, H. H., J Enciron Qual., 4, 219-22 (1975). (4) Bailev. D. S..“The Occurrence of Mercurv in the Fish and Sediment the North Fork of the Holston Rive; 1970-1972”, Va. State Water Control Bd., Basic Data Bull. 41,62 pp, 1974. (5) Hildebrand, S. C., Andren, A. W., Huckabee, J . W., in: “Toxicity to Biota of Metal Forms in Natural Waters”, Proc. of Int. ,Joint Commission on Great Lakes Research, R. W. Andrew, P. V. Hodson, and D. E. Konasewich, Eds., pp 211-32, Duluth, Minn., 1976. (6) Toole, T . W., Ruane, R. J., “Evaluation of the Mercury Monitoring Program-The North Fork Holston River”, Report EWQ-76-2, 33 pp, Tenn. Valley Authority, 1976. (7) Van Hook, R. I., Hildebrand, S.G., Huckabee. J. W.. Lindberg, S. E., Turner, R. R., Lund, J . R., “Biogeochemistry of Mercury in a River-Reservoir System: Impact of an Inactive Chloralkali Plant on the Holston River-Cherokee Lake”, ORNL/TM-6141, Oak Ridge National Lab, Oak Ridge, Tenn.. 1978. (8)U.S. Geol. Survey, CVater Resources Data for Virginia, 1975. (9) “Congressional Record”, Hearings on .‘Effects of Mercury on Man
OF
and the Environment”, Part 2 , July 29,30,1970, Serial No. 91-73, Appendix 3, pp 121-2,1970. (10) Hatch, W. R., Ott, W.L.,Anal. Chem., 40, 2085-7 (1968). (11) Feldman, C., ihid., 46, 1606-09 (1974). (12) Amer. Pub. Health Assoc., “Standard Methods for the Examination of Water and Wastewater”, 874 pp, APHA, Washington, D.C., 1971. (13) Thomas, R. L., Can. J . Earth Sci., 10,636-50 (1972). (14) Cranston, R. E., Buckley, D. E., Environ. Sei. Technol., 6,274-8 (1972). (15) Ritchie, J. C., McHenry, J. R., Gill, A. C., Limnol. Oceanogr., 18, 254-63 (1973). Cambray, R. S., Fisher, E. M., Nature, 242, (16) Pennington, W., 324-6 (1973). (17) Lindberg, S. E., Turner, R. R., ihid., 268,133-6 (1977). (18) Hem, J . D., U.S. Geological Survey Prof. Paper 713:19-24, 1970. (19) Hahne, H.C.H., Kroontje. W., Soil Sei. SOC.Am. Proc., 37, 838-43 (1973). ( 2 0 ) U.S. Dept. Interior, News Release, 6 pp, Sept. 16, 1970. (21) Lindberg. S.E., Andren, A. W., Harriss, R. C., “Geochemistry of Mercury in the Estuarine Environment”, in “Estuarine Research”, L. E. Cronin. Ed., Vol I, Academic Press, New York, N.Y., 1975. (221 deGroot. A. J . , deGoeij. J.J.M., Zegers, C.. Geol. Mijnhouu, 50, 393-8 (1971). (231 Hannan. P. J.. ThomDson. N. P.. J . Water Pollut. ControlFed.. 49,842-7 (1975). (24) O’Connor. D. J.. Water Resource., Res.. 12.279-94 (1976). (25) Shacklette, H. T.. Boerngen, .J. G., Turner, R; L., US.Geol. Surv. Circ. 644, 5 pp, 1971. (26) Lindberg, S. E.. Harriss, R. C.. Emiron. Sci. Technol., 8,459-62 (1974). (27) Anderson, A. A,, Grundforbattring, 28,95-105 (1967). ( 2 8 ) Kennedy, E. J., Ruch, R. R., Shimp, N. F., “Distribution of Mercury in Unconsolidated Sediments from Southern Lake Michigan”. Ill. State Geol. Survey. Environ. Geol. Note No. 44, 1971. (29) Robbins, J.A., Edgington. D. N.. Geochim. Cosmochim. Acta, 39, 285-304 (1953).
Receiced for recieic, ,Vocemher 16, 1977. Accepted February 2, 1978. Work supported b> the National Science Foundation-RAiVN Encironmental Aspects of Trace Contaminants Program under iVSF Interagenc) Agreement AELV-72-01243A03 with the Energy Research and Decelopmfnt Administration (noii,Department o/ Energy). Oak Ridge National Laboratory operated by I‘nion Carbide Corp. for the Department of Energy.
Characterization Techniques Applied to Indoor Dust Charles J. Weschler Bell Laboratories, Holmdel, N.J. 07733
Methods of characterizing dusts found within buildings were studied, using samples collected in Bell Laboratories’ facility a t Holmdel, N.J. Particle size and morphology were determined by optical and scanning electron microscopy. Quantitative analyses of C, H, and N were obtained, and semiquantitative analyses of elements with atomic numbers greater than 10 were carried out by energy-dispersive x-ray spectroscopy. Water soluble chloride, sulfate, nitrate, sodium, potassium, and calcium were determined using specific ion electrodes and energy-dispersive x-ray spectroscopy. The specific conductances of water extracts were measured. The principal elements present in the benzene soluble components were identified, and the organic functional groupings of these materials were examined by infrared spectroscopy.
0013-936X/78/0912-0923$01 .OO/O
@ 1978 American Chemical Society
Characterization of indoor dust should ultimately lead to a clearer understanding of the methods required to protect people and equipment against the problems caused by these particulates. However, there is little published information on the nature of indoor dust ( I ) . The chief purpose of the present study has been to explore means of characterizing indoor particulates. For convenience, the dust for trial characterizations was collected a t Bell Laboratories’ facility a t Holmdel, N.J. This building has a central air handling system with 85% NBS type filters; about 10%makeup outside air is added to the recirculated air. Experimental
Equipment. For microscopy with both transmitted and incident light, “reversed” binocular research microscopes were employed. Scanning electron microscopy was performed with
Volume 12, Number 8, August 1978 923
