Delfino CONTENTS Lead in Surface Waters ...82 Lead in Sediments ...82 Lead in Vegetation...84 Chemical Properties of Lead in Sediments ...84 Binding of Lead to Humic Substances...84 In 1
Trang 1Lead Distribution in Steele City Swamps* Shanshin Ton and Joseph J Delfino
CONTENTS
Lead in Surface Waters 82
Lead in Sediments 82
Lead in Vegetation 84
Chemical Properties of Lead in Sediments 84
Binding of Lead to Humic Substances 84
In 1970, Sapp Battery Service, Inc initiated its operations to process lead recovery from used automobile batteries The company gradually expanded its operation to process approximately 50,000 used batteries per week in 1978 Wastes from operations were dumped outside the plant and allowed
to run through adjacent wetlands, finally being discharged to Steele City Bay (Figure 6.1)
After 7 years of operation, in 1977, the first complaint about damage to cypress trees in adjoining wetlands was reported to the Florida Department of Environmental Regulation (FDER) FDER closed the site in January 1980
After the site was abandoned, EPA undertook emergency cleanup actions under provisions of the Clean Water Act, Section 311 The Sapp Battery site was included on the final National Priorities List in August 1982
After that date, EPA cooperated with FDER to conduct the Remedial Investigation/Feasi-bility Study (RI/FS) In this study, the on-site soils, groundwater, surface water, and sediments were examined
In 1985, Ecology & Environment, Inc (E&E) became involved in field investigations to further delineate the extent of the contamination Another draft feasibility study was finished by E&E in January 1987 See Appendix Table A6B.2
The analyses of lead were made from April 1989 to September 1992 Samples first collected at stations A through G (Figure 6.1) later extended further downstream in a series of sites: A, B, C, F, OF1, G, and OF2 (Figure 1.3) Descriptions of the sampling sites are given by Ton (1993) The chemical methods used are given in Appendix A6A, and Appendix A6B has a tabular listing of data
on lead in waters, sediments, vegetations, and related limnological data for April 1989 to May 1992
* Condensed by the Editor.
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Trang 2LEAD IN SURFACE WATERS
Lead concentrations in surface waters decreased downstream (Figure 6.2) Concentrations
in most samples were less than those reported in earlier years (Appendix Tables A6B.2 and
A6B.3), and most concentrations were less than the 0.03 mg/l regarded as safe for recreation, fish, and wildlife
LEAD IN SEDIMENTS
Concentrations of lead in sediments also decreased downstream (Figure 6.3) For the most part, lead concentrations were highest in the surface sediments with lower concentrations 15 to 45 cm below (Figure 6.4) These results indicated that the distribution of lead in sediments corresponds
to the surface water drainage pattern Relatively low lead concentrations outside the boundary of the study area suggest that the wetland acts as a filter to retain lead (Appendix Table A6B.5)
Figure 6.1 Location of sampling sites, Jackson County, Florida (Ton, 1990).
Site Location
Florida
Sapp Battery Site West Swamp
East Swamp
County Rd 280
Steele City Bay
N
U.S Rd
231
County
Rd 276
Destruction of Cypress Community
meters
200 400 600 800
A
B
C
Trang 3LEAD DISTRIBUTION IN STEELE CITY SWAMPS 83
Figure 6.2 Concentration of lead in surface waters as a function of distance from original discharge (Station
A in Figure 6.1 ) (Ton, 1990).
Figure 6.3 Concentration of lead in upper sediments (0 to 15 cm) as a function of distance from original
discharge (Station A in Figure 6.1) (Ton, 1990).
Figure 6.4 Lead concentrations in sediment profiles at Stations A through G in Figure 6.1 (Ton, 1990).
n
n
Sampling sites A
B
0.3
0.2
0.1
0.0
Distance, m
G
n
n
n n
n
n
Sampling Sites A
B
C F
D 0
Distance, m
G
500
400 300 200 100
0
500 400 300 200 100
600
Depth 0-15 cm 15-30 cm 30-45 cm
Sampling sites A1 A2 B1 B2 C1 C2 D1 D2 F1 F2 G1 G2
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Trang 4LEAD IN VEGETATION
Water lily (Nymphaea odorata) was the most popular species for the entire wetland, except site
A Leaves, stems, and roots of water lilies were separated for lead analysis Generally, concentrations
of lead in leaves and stems were slightly higher than those in roots However, high concentrations
of lead accumulated in roots were found commonly in other species (Appendix Table A6B.8)
CHEMICAL PROPERTIES OF LEAD IN SEDIMENTS
Sequential chemical extraction (Appendix A6A, Table A6A.1) was used to separate six compo-nents of lead in sediments, each followed by lead determinations Exchangeable lead was extracted with potassium nitrate solution; adsorbed lead was removed with potassium fluoride; organically bound lead with sodium phosphate; inorganic precipitated lead with EDTA; sulfide lead with nitric acid; and residual lead Results are given in Appendix A6B, Table A6B.9 and Figure 6.5
BINDING OF LEAD TO HUMIC SUBSTANCES
As already known from the literature and confirmed with the study of lead fractions (Figure 6.5), much of the lead combines with humic substances To measure the binding to the humic substances in the waters of the study area, 40 gal of surface water was collected from the control pond near the Sapp swamp in June and July 1991 A dialysis apparatus was set up (Figure 6.6) so that lead in solution on one side of a membrane could diffuse through the tiny pores, some becoming
Figure 6.5 Percentages of total sedimentary lead in each of six fractions at six stations in Figure 6.1 (Ton, 1990).
.
.
.
.
40
30
20
10
0
Organically Bound
Carbonate
Sampling Site
Sulfide
Residual
A B C D F G
Exchangeable
Adsorbed
Chemical State 50
Trang 5LEAD DISTRIBUTION IN STEELE CITY SWAMPS 85
bound by the humic substances in solution on the other side One side of the membrane had lead solution only, whereas the other side had lead solution plus that bound in the organic matter After suitable calculations were made using Scatchard graphs (Appendix Figure A6A.3), the ratio of lead bound to humic matter was found to be about 1.5 g lead per kilogram organic matter, slightly more
at higher pH, and about half the binding by a sample of humic materials (Aldrich Chemical Co., purified and freeze dried by Davis [1993])
A small amount (2.9 to 6.2%) of the organic humic molecules diffused in the other direction across the membrane, as measured with an instrument measuring the absorption of ultraviolet light The lower the pH the more diffused, suggesting an effect of pH in making the molecules more compact (already known from past publications) The humic substances from the bay diffused more than the sample of standard humic substance (less than 1%) In other words, the humic molecules from the control swamp were smaller than those in the standard humic material
Figure 6.6 Dialysis apparatus used for measuring the binding of lead by humic substances.
Dialysis Capsule Lead
Solution
Stirring Bars Pump
Stirrer
Sample of Dissolved Organics
Pump
Mf = Free Metals
Mt = Total Metals
Stirrer
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