Heavy metals in the surficial sediments of Fontana Lake, North Carolina

Water Res Voi. "~, No. 3. pp. 35i- 3.'.~, 1984 P~nted m Great Britain. All rights reser-.ed

(2~N3-i354 S4 $3 (;~)~ 0.00 Copy~ght ~ t984 Pergamon Press ktd

HEAVY METALS IN THE SURFICIAL SEDIMENTS OF F O N T A N A LAKE, NORTH CAROLINA A. R. ABERNATHY l, G. L. L.~RSONz and R. C. MATHEWSJR" ~Environmental Systems En~needng Department. Clemson University. Ctemson, SC 29631. :National Park Service. Midwest Regional Office. 1709 Jackson Street. Omaha. NE 68102 and -~Uplands Field Research Laborato~. Great Smoky Mountains National Park. National Park Service. Gatiinburg. TN 37738. U.S.A. (Received Juh, 1983)

Atvstract--Concern about the possible contamination by heavy metals of Fontana Lake !reservoir) and potential sources of such materials led to a study of surficial sediments. Samples of sedimcnt were collected in the main body of the lake and near the mouths of its major tributaries and anatayzed for magnesium. iron. aluminum, manganese, zinc, copper and mercury. Although the drainage area of the reservoir is primarily forested and rural without major industrial developments, the results indicated that manganese. copper and zinc were present in concentrations similar to areas receiving industrial pollution. Chemical analyses of pyritic materials in the watershed (e.g. ~hists or Anakeesta formation) showed relatively high concentrations of many of the same metals present in Fontana sediments. It appears, therefore, that the metals in the lake sediments represent materials derived from geological sources, although airborne contributions of certain metals cannot be ruled out. Key words--lake sediments, heavy metals, contamination. Anakeesta formation, sulfide deposits

INTRODUCTION

STLDY AREA

Metal compounds in lake sediments can result from human perturbations (Aston et al., 1973; Cahill, 1981; Edgington and Robbins, 1976; Fitchko and Hutchinson. 1975; Iskander and Kenney, 1974) and also from undisturbed conditions (Abernathy, 1979; Fitehko and Hutchinson, 1975; lskander and Kenney, 1974: Waiters et al., 1974). At Fontana Lake (reservoir) in western North Carolina, the geology of the forested-rural drainage basin includes pyritic materials which have relatively high concentrations of heavy metals (Hadley and Goldsmith, 1963). In that part of the drainage basin which includes the Great Smoky Mountains National Park, these materials are represented by the Anakeesta formation which is a schist of Precambrian age (Herrmann et al., 1975; King et al., 1968). Within the remainder of the basin they are represented by mineralized deposits characterized by black schist and metasandstone formations (L. S. Wiener, Geologist, Division of Natural Resources, Department of Geology, North Carolina, personal communication). The presence of these sulfide-enriched formations suggests the possibility of substantial inputs of metal compounds to the reservoir sediments. This prompted the present study of heavy metals in surficial sediments within the reservoir. Chemical analyses included the major heavy metals identified in Anakeesta leachate by Huckabee et al. (1975) plus mercury, since the latter has been reported from nearby reservoirs in South Carolina (Abernathy, 1979).

Fontana Lake, located along the southwest border of Great Smoky Mountains National Park, provides power generation and flood regulation on the Little Tennessee River. Physical characteristics of the lake are given in Table I. The major rivers discharging into the lake are the Little Tennesse, Tuckasegee and Nantahala (Fig. I). Eagle, Hazel, Forney and Noland Creeks also empty into the lake. The Oconaluftee River drains into the Tuckasegee River about 13 km upstream from the lake. The drainage basin encompasses about 4069 km-'. PROCEDURES

Samples Sediment samples were collected at 1l stations (Fig. I ) on 8 May 1978, using a standard Ekman dredge. Each sample was placed in a clean plastic bucket, mixed, transferred to a wide-mouth plastic bottle which had been acid washed, and then was shipped to Clemson University for analysis. Upon receipt, each sample was carefully mixed and air-dried at 87~'C to avoid loss of volatile metals such as mercury. Table I. Physical charactcristic~ of Fontana Lake (Tennessee Valley Authority. 1954. 1965) Length Maximum width Surface area Maximum depth Mean depth Volume Normal pool elevation Shoreline length

351

47 km 0.97 km 4265 ha 146 m 4l m t,78 x t0 ~ rn ~ 521 m 399 km

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I.F~.°,. Fig. t. Map of the study area showing the locations of the sample sites. Each sample was finely ground with an agate mortar and pestle. A portion of the pulverized material was weighed. transferred to a 250-ml Ertenmeyer flask and refluxed 1 h with 20 ml of aqua regia to dissolve precipitated or sorbed metal compounds. The digested samples were then diluted with distilled water, filtered through Whatman glass fiber filters, and transferred to 50-ml volumetric flasks. Transfers were made quantitatively, and the filters and flasks were rinsed to remove traces of metal compounds. The d n s i n ~ were added to the samples and subsequently diluted to 50 ml with distilled water

A Perkia-Elmer Model 403 atomic absorption spectrophotometer with a deuterium arc background eorrector was used for the analyses. A Perkin-Elmer HGA-2100 heated graphite analyzer was used for the aluminum, manganese, zinc and copper analyses. Magnesium and iron analyses were made by direct flame aspiration with an ac~tyteae./air flame. The cold vapor technique was used for analyses of mercury (APHA, 1975). Prepared metal standards from Fisher Scientific were diluted with aqua regia and distilled water to approximate the matrix in the digested sediment samples. Calibration

Table 2. Heavy metal concentrations in the surfw.ial s~liments of Fontana Lake by sample group and station

Group

Station No.

Sample depth (m)

o

8 20

mg kg -j dry wt Fe

Mn

Zn

AI

......... Mg Cu

Hg

Major River 53,950 1200 47,600 720

200 63.000 7970 94 67,900 6000

50 53-

1.00 0.60

50.775 960

197 65.450 6985

52

0.80

41.800 28.800 38.700 30.000

170 130 210 150

5350 3720 5040 4600

28 2,1 72 60

1.00 0.67 0.76 076

34,825 406

165 40.200 4678

46

0.80

14 38.600 490 9 33.600 470 Average 36.100 480

168 47,800 4900 I90 43.300 6750 179 45.550 5825

28 29 28

0.75 0.86 0.80

61.700 680 61.000 300 68.400 1200

190 70.600 6800 190 96.690 5100 200 84,600 5100

52 52 55

'.87 I0.00 3.60

63.700 45,832

193 83.963 5667 181 57.699 5575

53 46

5.2 99

Average North Shore 2 3 4 5

7 9 16 22 Average

550 265 410 400

40.t]00 36.400 47.700 36.700

South Shore 7 8 Main Lake 0 1LI II

40 75 90 Average Grand average

733 610

Heavy metals in sediments curves ~ere prepared by analyzing several concentrations of each standard. The sample stations were grouped in order to compare concentrations of metals in the sediments as influenced by _qreams draining specific portions of the basin. Eagle, Hazel, Forney and Noland Creeks all flow into the lake from the Great Smoky Mountains National Park. These streams were designated as the North Shore Group. Stations 1 and 6 ~ere designated as the Major River Group. Stations 9, 10 and t I were designated as the Main Lake Group. Stations 7 at,.d ,_,'3were located within the areas of influence of Wolf Creek Panther Creek and Stecoah Creek/Sawyer Creek. respectively and were designated as the South Shore Group,

RESULTS

The samples from the Major River Group were greater in concentration of each metal than the north Shore and South Shore Groups, except for Hg, which was the same (Table 2). The Main Lake Group was higher in concentration of all metals, except Mg, than the samples from either Shore Group. The samples front Hazel and Eagle Creeks were higher in Cu than the Main Lake sediments (Table 2). Comparing the Main Lake Group and the Major River Group, the former had the highest concentrations of Fe, A1 and Hg while the latter was highest in Mn and Mg; Zn and Cu concentrations were approximately equal in both groups. Although the averages for the South Shore stations were slightly higher than those for North Shore stations, except for mercury, which was the same, and for copper, which was almost twice as high, the differences were small. Thus, the inputs from the smaller streams seem nearly the same except for the high concentrations of Cu from the Hazel Creek and Eagle Creek areas. The major rivers, however, seem to transport the highest concentrations of Fe, Mn, AI and Mg. Except for Hazel and Eagle Creeks, the major rivers also appear to transport the highest concentrations of Cu.

DISCUSSION

The metal compounds found in high concentration in sediments from Fontana Lake are compatible with the analyses for Anakeesta formation (Hadley and Goldsmith, 1963) and the metals in Anakeesta leachate reported by Huckabee et al. (1975). Although particle size was not examined, Fontana Lake sediments have high accumulations of some metals in comparison to sediments from other unpolluted areas. In fact, concentrations of Mn, Cu and Zn were high, even in comparison to sediments from some polluted areas (e.g. Cahill, 198t; McKinney and Milgaard 1980; and Pita and Hyne, 1975). Thus, there appears to be an abundant source(s) of these metals contributing to Fontana Lake sediments. In general, the metal concentrations in the reservoir, except Cu, appeared to be more related to

553

stream size than location. Since the basin is sparsely populated (five county average of 76.7 people per km:), predominantly rural (74.Y'o), contains no major industrial developments and is covered in second ~ o w t h forest, these data suggest that the contribution of heavy metals is primarily geologic in origin. If this is correct, the contributions from the Anakeesta formation in the park and from mineralized deposits elsewhere in the basin appear similar. However, atmospheric inputs from the combustion of fossil fuels and from metal smelters and other industries may also be important (Goldberg et al.. 198t: Weirsma et al., 1979). The amount of contamination from these sources is not known. Copper was found to be more concentrated in sediment samples from the mouths of Hazel and Eagle Creeks than at any of the other sampling locations. Espenshade (t963) reported that copper mines were formerly active in the drainage basin of both those streams and measured Cu concentrations of 0.02-0.04 mg 1- ~in water samples from six streams in the r e , o n . Streams draining the mines and ore dumps contained 0.1 ppm copper or greater. Thus, the occurrence of elevated Cu concentrations in the sediments of these two locations is reasonable. Samples from the main lake were higher in each metal than the other samples, except for magnesium and for copper from Eagle and Hazel Creeks. Dissolved Fe probably becomes oxidized in the epilimnion of the reservoir and precipitates as hydrous oxides. This could result in the enrichment in iron seen in the main lake sediments and could also assist in enriching the main lake sediments in some of the other metals by co-precipitation or sorption. Also, precipitation of these metal compounds from the dissolved state would result in greater concentrations in deep water sediments compared to sediment near the mouths of streams where waterborne particles would continuously dilute the autochthonous sediments with allochthonous particles derived directly from geological substrates. It is also possible that finely divided autochthonous sediment could become resuspended in near-shore areas and ultimately settle in deep water to become part of the main lake sediments. The results of this study suggest that inputs of metal compounds may be .expected from lake or reservoir drainage basins with mineralized deposits. Metal accumulations in the sediments may pose a biological risk in the future. This may be especially important should lake or reservoir acidity increase owing to impacts from acid precipitation upon this soft water system. Acknowledgements--We are grateful to the staff of Great

Smoky Mountains National Park for their assistance on the project. Special thanks are Wen to Lourrie Spraque and David Silsbee for their assistance collecting the sediment samples. Thanks also are extended to Ray Herrmann and Jim Wood for reviewing the manuscript. We thank L. F. Owens for analyzing the sediment samples.

:5-;

A R. ABERNADt'~ el ai. R EFERENCt'S%

Kbernath? .A R. {19"~9} Hea~2, ,'z,~,~a~ c o n t a ~ m a t l o n t~( -,urface waters and fish flesh !n Sou!h Carolina. Repor~ N,,. "7'4. Water Resources Research Institute. Ci,.nns,m L'0.i~ersit>. Clemsofz, SC. APHA , 19751 Standard Metlu~d~ .;~Jr me 4~_ai'~~ti ol ~l'atcr and Wastewa[er. 14th Edition. American Pubhc Heaith a~,~ociauon. New Y,.,rk a,q o n S. R.. Brut.,. D., Chester R. and Padgham R_ C i1973) A possible indicator of technoio~cal growth. ~atur¢ 241.45(~-451. Cahfll R A. ~t981~ Geochemistry of recent Lake Michigan sed, mcnts. Circular 517. Illinois State Geoto~cal Sur',ey. Champaign. IL. Edgmgton D N. and Rohbins J. A. ~1976~ Records of lead ~epos~tion in Lake Michigan sediments since 1880. En,'ir 3ct. Techmd. 10, 266--274. Espenshade G. H. { t9631 Geology of some copper deposits m North Carolina, Virginia, and Alabama U.S. GeM .Tucv. B u l l 1142-1. Fitchko J. and Hutchinson T. C. ~1975) A comparative study of heavy metal concentranons m river m o u t h sediments around the great lakes, d. Great Lakes Res. I. 4(~78. Goldberg E. D.. Hodge V. F.. Grilfin J J.. Koide M, and Ed~ngton D. N. (t981) Impact of fossil fuel combustion on the sediments o f Lake Michigan. Em'ir. Sci. Technn[. 15, 466--471. [ladlcy J. B. and Goldsmith R. ~1963) Geology of the eastern Great Smoky Mountains, North Carolina and Te~messee. U.S. Geological Survey. Profe,Monal Paper 349-B, Herrmann R.. Morgan E. U and Green R L. (1975) The

nature of acid pollution En a small mountain ~tr~t~m. Greal Smoky Mountains Pr¢~cet'dttt,z~ ¢Jf t/l(" _~4zh -JttHu~l[ ~[eetinJ& Southeastern .'~cc/u-r. Geo/.o',~c~,'/ ~, ,¢~=.,/~ .,: -Imcrt,_'a. Voi. 7. p. 499. Huckabee J W.. Goodyear C. P and Jones. R D. ~t975~ AcM rock in the Great Srnokie~: unantic',pated impact or: a q u a n e biota of road construcuon in rebnons of sulfide mineralization. Trans. Am. Fish. Soc. !tl,4, 67'7-6S4. lskandar I K and Keene~ D. R. {19741 Conceutration of heavy metals in sediment cores from selected Wisconsin L a k e . Ent'ir. &'i. Tech~tol. 8, 165-170 King P. B.. Newman R. B. and Hadley J. B. { 1968; Oeolog3 of the Great Smoky M o u n t a i n s National Park. Tennessee and North Carolina. U S . Geological Su~c3. Professional Paper 587 McKinney D. and Milgaard D. ~1980~ The occurrcI~.ce ~! heavy n'ietals in Norris Reservoir. TN Division of Pubhc Health. Di~ision of Water Quahty Comrol. Kno,~,.ille Basin. 25 pp. Pita F. W. and Hyne N. J. (1975) Thedeposltionai ¢nvm~nment of zinc, lead. and cadmium m reservoir sediments Wetter Res. 9. 701-706. Tennessee Valley Authority {1954) Fontana project: _~ummary' of principal features. TI-'A Btdl. No. 14-3. 5 pp. Tennessee Valley Authority (1965) Fontana Dam. F|'A Bull. No. F6516R, 4 pp. Waiters k J., Wolery T. J. and Myser R. D. t1974~ Occurrence o f As. Cd. Co, Cr. Cu. Fe. tlg. NL Sb, a0.d Zn in Lake Erie sediments. Proc. 17th Conl~ Great Lake.~ Res.. htt Ass. Great L a k e s Res. 219-234. Wcirsma G. B., Frank C. W.. Brown K. W and Davison C. 1. t 1980~ Lead particles in the Great Smok) Mountain~ Biosphere Reserve. U.S. EPA. Publication 60f3 4-80-¢)02.