Summary of Sediment Chemistry Research at Old Woman Creek, Ohio

J. Great Lakes Res. 18(4):603-621 Internat. Assoc. Great Lakes Res., 1992

SUMMARY OF SEDIMENT CHEMISTRY RESEARCH AT OLD WOMAN CREEK, OHIO

Gerald Matisoffl and Joseph P. Eaker 2 IDepartment of Geological Sciences Case Western Reserve University Cleveland, Ohio 44106

2Now at Bureau of Underground Storage Tanks Division of Water Resources Department of Environmental Protection CN 029 Trenton, New Jersey 08625-0029 ABSTRACT. Sediments are important at Old Woman Creek National Estuarine Research Reserve (OWC) and similar environments because suspended sediments provide a medium for the transport of many nutrients and toxic substances and bottom sediments may serve as either a sink or source of these substances, can influence estuarine productivity and water quality, can serve as substrates for much of the wetlands microscopic and macroscopic flora and fauna, and can contain a record ofpast conditions at the depositional site. Previous research at OWC has determined that the major sources of sediment supplied to the estuary are from soils and tills and the Berea Sandstone in the drainage basin. These sediments and their associated chemical species are primarily delivered to the estuary during storm events and the majority of the suspended sediment that washes into OWC is trapped and accumulates at the bottom of the estuary. Some postdepositional mobilization and sedimentwater exchange of metals such as cadmium (downcore transport) and nutrients such as silica (release from sediments) has been observed and fluxes calculated. Groundwater seepage into the estuary varies with annual rainfall and is greatest near the estuary perimeter. Solute fluxes resulting from groundwater seepage are generally small compared to total fluxes as measured using bottom chambers. Benthic macroinvertebrates may contribute significantly to internal recycling. Both field measurements and computer simulations indicate that the water and solute budgets are controlled, in part, by a barrier sandbar which sometimes separates the estuary from Lake Erie. INDEX WORDS: Sediment chemistry, lake sediments, fresh water estuary, suspended sediments, sediment-water exchange, seepage flux.

INTRODUCTION

their introduction into nearshore freshwater or oceanic regions, nutrients and pollutants such as pesticides, trace metals, and radionuclides are sorbed onto coatings of fine-grained clay particles or particulate organic matter suspended in the water column. Under the influence of physical processes such as gravitational settling and turbulent eddy diffusion, geochemical processes such as adsorption, flocculation, and precipitation, and biochemical processes such as filter feeding, most of these particles are deposited at the bottom in nearshore environments where they undergo burial and chemical reaction. A second reason for studying lake and river bottom sediments is that they are not simply a sink for hazardous materials that are as-

The purpose of this paper is to summarize the existing body of information on sediments and sediment chemistry that has been performed at Old Woman Creek National Estuarine Research Reserve (O.W.C.N.E.R.R.). We also report some of our new results on groundwater advection and solute transport from sediments at Old Woman Creek. There are several important reasons for studying sediments in this type of environment. First, many nutrients and toxic substances such as heavy metals, pesticides, PCBs, and radioactive elements are associated with sediment particles, so that the fate of these materials is closely tied to the fate of the sediment particles themselves. Upon

603

604

MATISOFF and EAKER

sociated with the particulate phase. They are also a potential short-term source. These materials may remain in the sediment where they are reworked by physical and biological mixing processes and buried or decomposed, solubilized, and released to the sediment pore water, from which they may be refluxed to the lake or estuarine water by diffusion, groundwater advection, bioturbation, and resuspension. A third reason for investigating sediments at Old Woman Creek is that they can have a significant impact on estuarine productivity and water quality. In fact, the clearing and draining of wetlands throughout the western Lake Erie watershed during the past 100-150 years has resulted in an enormous increase in the influx of sediment to the lake compared to pre-historic times and in significant changes to the macrobiological community. It seems unlikely that Lake Erie would have displayed so many ecological and water quality changes in response to changes in the watershed were it not for the sediments promoting those changes. Habitats were lost, fish eggs smothered, light penetration decreased, burial rates of organic matter increased, nutrients and pollutants were delivered more effectively to the lake, etc., all in response to increased sediment loading to the lake. Fourth, suspended and bottom sediments serve as substrates for much of the wetland's and nearshore microscopic and macroscopic flora and fauna. Changes in the nature and/or rate of delivery of sediment to the lake and within the estuary are likely to result in spatial and temporal changes to that biological community. This can have a significant impact on the rates of nutrient recycling, food supplies, habitat development, sediment recycling, etc. A fifth reason for studying sediments is that due to burial they contain a record of past conditions at depositional sites. Our ability to decipher that record depends upon our understanding of all the physical, chemical, and biological processes that affect sediments from the time they are first entrained at the source location until their ultimate burial beneath the estuary or lake. Finally, knowledge of past conditions can prove to be very useful in the development of resource management plans. For example, knowledge of nutrient and sediment loads to Lake Erie during the past 100-150 years corresponds to a spectrum of conditions that ranged from oligotrophic to eutrophic. Although the biogeochemical ecosystem for Lake Erie is quite complicated, this information greatly aids in

establishing cause and effect relationships for water quality and biological speciation and therefore serves as critical information to establishing water quality and quantity and sediment management criteria. Numerous studies of marine estuaries have demonstrated significant changes in the composition of the river water and suspended sediment as they are transported through the estuary enroute to the ocean. The functional similarity of freshwater estuaries with their marine counterparts is unclear because the chemical differences between a river and a lake are more subtle than those between a river and the ocean. The concept of "Great Lakes estuaries" has been intensely debated (Nixon 1990, Herdendorf 1990, Dyer 1990, Odum 1990, Schubel and Pritchard 1990), and Herdendorf (this special issue) and Heath (this special issue) present evidence for chemical gradients that support the use of the word "estuary" when used in reference to Great Lakes rivers and wetlands. The magnitude of sediment-water exchange depends upon complex interrelationships among physical and chemical processes acting on suspended and settled sediment particles, estuarine waters and sediment pore fluids, and biota (Fig. 1). Not all of these processes are well understood in general, and even less is known about some of them at Old Woman Creek. This paper will focus on reviewing the data on the processes depicted in Figure 1 that has been collected at Old Woman Creek. SEDIMENT SOURCES Old Woman Creek is a small tributary to the southwestern margin of Lake Erie (Fig. 2). It lies on the eastern eroded limb of the Cincinnati-Findlay Arch approximately 35 miles east of the arch axis. The Precambrian basement rocks are approximately 2,600 feet below the surface of the study area (Buchanan 1983). The consolidated rock formations that outcrop in the Old Woman Creek drainage basin and are potential sediment sources consist of the Devonian Ohio Shale, the Mississippian Bedford Shale, and the Mississippian Berea Sandstone. The local geology, stratigraphy, lithologies, and thicknesses have been detailed by Pepper et al. (1954), Herdendorf (1966), and Buchanan (1983). The late Devonian Shale is over 500 feet thick and consists of two recognizable units (Huron Shale and Cleveland Shale) in the study area. The Huron Shale is a hard, dense, grayish

SEDIMENT CHEMISTRY AT OLD WOMAN CREEK

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black shale with large basal concretions. The Cleveland Shale is a hard, dense, black to brownish black carboniferous shale containing argillaceous limestone beds with cone in cone structures throughout. The Mississippian Bedford Shale ranges from 0 to 160 feet thick due to channel erosion by the overlying Berea Sandstone. It is a soft, red to gray argillaceous shale containing resistant siltstone layers at the base. In most places the Berea Sandstone overlies the Bedford Shale. This unit varies from 10 to 260 feet thick. The Berea is a hard, dense, light bluish gray to buff colored quartzose sandstone which is generally medium to fine grained. These Paleozoic rock formations are overlain in much of the drainage basin by Quaternary glacial deposits (Fig. 3). During the Pleistocene Epoch the

FIG. 2. Location and generalized map of Old Woman Creek Estuary (after Buchanan 1983).

area experienced several periods of glaciation (Buchanan 1983). Although some Kansan, Nebraskan, and Illinoian till and sand and gravel deposits exist, the most abundant and widespread glacial deposits in the drainage basin are the glacial tills and lacustrine deposits of Wisconsin Age. Buchanan (1983) found that the majority of the sediment being deposited in the Old Woman Creek Estuary originates on a till plain in the upper creek basin which he identified as the "Late Cary" till (Cambell 1955) or Hiram till (Herdendorf 1963). These tills averaged 28% sand, 36% silt, and 35070 clay with the clay fraction consisting of quartz, roughly equal amounts of illite and chlorite, lesser amounts of kaolinite, and small amounts of mixed-layer chlorite-smectite, discrete smectite, mixed-layer chlorite-smectite, and feldspars (Buchanan 1983). Six primary soil associations have been identified in the Old Woman Creek drainage basin (Buchanan 1983, Frizado et al. 1986). These soils are characteristic of the Late Wisconsin glacial environments and reflect the characteristics of the glacial or near-glacial environments under which the parent material was deposited. Frizado et al. (1986) performed a discriminant analysis on the mineralogy of the bulk sediment and determined that the probable sources of estua-

606

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FIG. 3. Generalized cross section of bedrock and overlying sediments beneath Old Woman Creek Estuary. Approximate horizontal scale is 3 miles (after Buchanan 1983).

rine sediment consist of approximately equal parts of (1) glacial till, glacial lacustrine sediment, and soils; and (2) the Berea Sandstone. They found that the Ohio Shale was not a significant contributer to the sediment in the estuary. They feel that the contribution to the sediment load from the Berea is over-estimated by the procedure because export of fine-grained suspended sediment from the estuary will increase the relative proportion of sand in the bottom sediments. They also measured trace element concentrations in humic extracts of sediments (Fig. 4). They performed linear regressions of all possible pairs of trace elements within the humic substances and within each core and found that there are two similar, but different types of humic substances being deposited throughout the estuary. They surmise that the sources for these different humic materials are aquatic plants and marsh species in the main body of the estuary and terrestrial vegetation such as fallen leaves in the southern portion of the estuary.

SUSPENDED SEDIMENTS Detailed studies of sediment dynamics are essential to the development of estuarine sediment, nutrient, and toxic substance management schemes. Previous work has determined that non-point agricultural sources of sediment are a major contributor of nutrients and other pollutants to the Great Lakes (IJC 1978, 1980; Logan 1982; Yaksich et al. 1982, 1985; Wall et al. 1982; Baker 1985; Logan 1987). Yaksich et al. (1985) and Logan (1987) demonstrate that about half of the total phosphorous load to Lake Erie is from non-point tributary sources, of which about 30010 is bioavailable. Suspended sediments from tributaries are also enriched in metals (IJC 1978), but agricultural land practices does not appear to be an anthropogenic source of metals. Organic pollutants such as pesticides (Frank et al. 1982), herbicides (Baker 1985), and PCBs (Thomann and Di Toro 1983) have recently been demonstrated to be transported by tributaries from agricultural areas into Lake Erie.

SEDIMENT CHEMISTRY AT OLD WOMAN CREEK

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Most of the nutrient and material transport into Lake Erie occurs during storm events and the spring runoff period (Yaksich et al. 1985). Yaksich et al. (1982) found that some materials such as total phosphorous are associated with the suspended sediment and tend to increase in concentration with increasing flow, while others, such as chloride, that are not associated with the suspended load, tend to decrease with increasing flow. The importance of storm events on phosphorus transport in the Maumee River is illustrated in Figure 5 (Yaksich et al. 1982). Studies on other rivers draining agricultural land have also demonstrated the importance of storm events on material transport to Lake Erie (Baker 1985, Richards and Baker 1985). Recently, Klarer (1988) performed a preliminary study at Old Woman Creek and found that nutrient and metal chemical transport in the estuary were primarily attributable to the effects of storms (Table 1). Although he was not able to quantify volumetric flow rates, he found that the estuary is a sediment, metal, and nutrient sink. He also found that the removal amounts were greater than can be accounted for from physical sedimentation alone, so that geochemical and biological removal processes must be occuring. In addition, he found that the estuary is a source for some spe-

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FIG. 5. Daily total phosphorus loads in the Maumee River at Waterville, 1975. Most of the phosphorus is associated with the suspended load (from Yaksich et aI. 1982).

cies (e.g., K+), at least during some times of the year. Previous work in marine estuaries has been extensive and has clearly demonstrated the extent of physical, geochemical, and biological processes that affect river-borne sediments and solutes during transport to the sea (see summaries by Cronin 1975, Wiley 1978, and Kennedy 1984). Many of these processes are similar to those emerging from recent studies in freshwater systems. For example, Schubel (1974) and Zabawa and Schubel (1974) reported that runoff from Hurricane Agnes introduced as much sediment into the upper 40 km of Chesapeake Bay in I week as would be normally deposited in 50 years. Yaksick et al. (1982) also concluded that most of the material transport into Lake Erie occurs during storm events. Boyle et al.

608

MATISOFF and EAKER

TABLE 1. Correlation coefficients between turbidity and selected chemical parameters at each sampled site in Old Woman Creek Estuary (from Klarer 1988). Parameters Specific Conductance Oxygen pH Total Alkalinity Orthophosphate Silicate Nitrate Nitrite Ammonia Chloride Sulfate Calcium Magnesium Potassium Sodium Iron Copper Manganese Zinc

A -.245 -.089 -.477* -.636** .462 .101 .493* .425* .647** -.422 -.439* -.723** -.596** .876 -.256 .912** .815** .752** .769**

B -.300 .024 -.269 -.509** .242 .145 .330 .371 .556** -.402 -.527** -.740** -.604** .778** -.258 .928** .933** .524** .909**

C -.182 -.192 -.604** -.604** .694** .280 .120 .068 .423** -.318 .058 -.603** -.638** .794** -.122 .970** .910** .052 .936**

Sites E

D

-.014 -.345 -.677** -.602** .725** .181 .483* .305 .708** -.154 .170 -.413** -.375 .9804** -.024* .848** .716** .004 .730**

F

-.182 -.248 -.582** -.574** .609** .416 .244 .100 .534** -.327 .086 -.416* -.457 .729* -.154 .833** .550** -.238 .512*

-.138 -.237 -.562 -.459* .696** .538** .399 .208 -.068 .359 .162 -.394 -.422 .782** -.098 .826** .668** -.028 .710**

G

-.233 -.305 -.727** -.576** .634** .417 .222 .084 .636** -.420 .033 -.506* -.494 .672** -.280 .826** .697** -.047 .708**

H -.026 -.370 -.674** -.382* .761** .614** .554** .240 .821** -.467* .223 -.275 -.134 .785** -.076 .812** .703** .150 .637**

I .376 -.177 -.203 .344 .183 .389 .312 .341 .563** -.453 .225 -.058 .404 .798** .352 .901** .628** .523* .653**

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(1974) demonstrated that some materials behave conservatively in the estuarine environment while others are non-conservative. They found iron was preferentially removed from the water while Bradford (1972) reported that zinc was added to the estuarine water. Preliminary work by Klarer (1988) reveals that many nutrients and metals also behave non-conservatively in a freshwater estuary. A major difference between marine and freshwater estuaries is the absence of a specific turbidity maximum in the freshwater environment. Although geochemical removal processes are most effective at the turbidity maximum (Sharp et al. 1984), the lower portion of Old Woman Creek is thought to serve as the geochemical equivalent because of the high ratio of surface area to depth and the frequent resuspension of bottom sediments (Fig. 6, Klarer 1988). The majority of suspended sediment that washes into Old Woman Creek Estuary is trapped and accumulates at the bottom of the estuary. Sedimentation rates are not well known, but Buchanan (1983) determined a 14C accumulation rate of 0.76 mm/yr and estimated that since the advent of row-crop agriculture in the 1800s the sedimentation rate in-

creased to about 10 mm/yr. He also determined a simple sediment budget based on sampling locations upstream of the estuary and within the estuary which were sampled 10 times in order to represent average conditions along the stream. He calculated that 20010 of the material in transport in the creek may be deposited in the estuary under normal conditions, but that about 40% of the material is deposited within the estuary during highflow storm events. SEDIMENT CHEMISTRY

The chemistry of the sediments has also been investigated, although the type and quantity of data collected varies widely among the different studies. Frizado et al. (1986) determined that the composition of the interstitial waters is not related to the bulk mineralogy of the sediments, although they did find that the concentrations of most trace metals are higher in the interstitial waters than in the overlying water. They concluded that the sediments will act as a source of trace elements to the estuary. Matisoff and Eaker (1989) also examined the interstitial waters and used flux boxes in order

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to calculate solute exchange between the pore waters in the sediment and the overlying water. They found that the fluxes of iron, copper, and zinc were usually not significantly greater than zero. There were occasional > zero fluxes for copper

609

and zinc. They did, however, measure a statistically significant flux of manganese of 1.1 millmoles/m2 /day during the warm season. Pfister and Frea (1989) also examined the chemistry of the sediments in a few cores at Old Woman Creek. Their data for cadmium concentrations in a nitric acid leach (Fig. 7) is remarkably like that of the hydrous oxide extraction reported in Frizado et at. (1986). They hypothesized that the downcore variation in cadmium concentration was due to downcore variations in aerobic and anaerobic microbial activities. However, their measurements of aerobic and anaerobic microbial counts showed little or no direct correlation with Cd concentration in Old Woman Creek water. They did find some aerobic growth in samples spiked with additional cadmium. This metal profile is different from those reported from cores obtained from Lake Erie (Nriagu et at. 1979). In most of the cores examined from Lake Erie and other freshwater and marine environments, the concentrations of trace elements are usually higher near the surface than they are deeper in the sediment. The usual interpretation (also used by Nriagu et at. 1979) is that this is due to anthropogenic increases of metals in the environment which leads to higher depositional fluxes. Holdren et at. (1984) also showed that a similar profile can result from downcore diffusion and fixation of a mobile substance that has a higher overlying water concentration than in the pore waters. The amount of organic material in one core at Old Woman Creek was measured by Shane (1982) and reported by Buchanan (1983). The "loss on ignition" data plotted as fraction organic carbon is shown in Figure 8. Buchanan (1983) interprets the abrupt increase in percent organic material in the core above a depth of 150 cm (5 ft) as a change in estuary conditions from terrestrially imported organic matter to those suitable for the establishment of a thriving in situ floral community. He supports his interpretation by noting that in contrast to the lower fine-grained organics, the upper organic zones contain matted rootlets, remains of decayed leaves and contemporary aquatic plants, and small twigs. Buchanan (1983) also reports that the vegetal layers in the upper meter are separated by thin, largely inorganic zones of gray or brown silty clay. He interprets the dark, organic-rich layers as indicating periods in the past when the estuary was shallow enough for aquatic plants to survive while the horizons which contain primarily inorganic material represent deeper water intervals on the

610

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FIG. 8. Organic carbon fraction in Old Woman Creek sediments (data from Shane 1982 as cited in Buchanan 1983).

Once deposited, the sedimentary particles are susceptible to resuspension, chemical and biological action, and burial (Fig. 1). Extensive studies have been carried out on the effects of molecular diffusion sediments on the chemical flux through benthic deposits, but the body of literature on the effects of biogenic alteration and groundwater advection on the chemical flux is much less. Measured fluxes of dissolved species frequently exceed that calculated by assuming only diffusional transport, indicating that additional parameters must be taken into account (Matisoff et al. 1985, Cornett et al 1989). Numerous studies (Lerman and Jones 1973; Berner 1974, 1980; Matisoff et al. 1980, 1981; Martens and Burdige 1988; and many others) have evaluated the importance of diffusional transport, and more recent studies (Aller 1978, 1980, 1982; Fisher 1982; Matisoff et al. 1981, 1985; Matisoff 1982; and many others) have demonstrated the importance of benthos on chemical exchange between sediments and water. Vanderborcht et al. (1977) demonstrated that wave action can also significantly affect the chemical (silica) flux. We report here three different methods we employed to estimate the flux of solutes across the sediment-water interface at Old Woman Creek. The first method, termed "direct flux," involved

SEDIMENT CHEMISTRY AT OLD WOMAN CREEK TABLE 2. Comparison ofsolute fluxes determined by three techniques at one location along the eastern edge of Old Woman Creek Estuary near Star Island in 1988. Diffusional fluxes were calculated from pore water profiles in March 1989 (from Matisoff and Eaker 1989).

61 em

T

Calcium (moles/m 2 /day) Sept. Oct. Manganese (J.tmoles/m2 /day) Sept. Oct. Bicarbonate (moles/m 2 /day) Sept. Oct. Dissolved Silica (J.tmoles/m 2/day) Sept. Oct. Nitrate (moles/m 2/day) Sept. Oct. Ammonia (I/-moles/m 2/ day) Sept. Oct.

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monitoring the time rate of change of concentration within a bottom chamber (flux box) of known volume and bottom cross-sectional area. The second method, termed "diffusional flux," calculates the flux assuming Fickian diffusion by using diffusion coefficients and pore water concentration gradients. The third method, "seepage flux," involves direct measurement of groundwater seepage across the sediment-water interface and calculates the solute flux as the water flux times the solute concentration in the water at the sediment-water interface. The results of our flux estimates are reported in Table 2 and are discussed in more detail below. Direct Flux Measurements The solute flux across the sediment-water interface was determined using acrylic and polyethylene flux boxes. A schematic of the acrylic flux box is shown in Figure 9. It was constructed as a 50 cm x 25 cm x 20 cm acrylic box with an open bottom. Side

arms were attached along the middle of the box to ensure that it is inserted to the same depth ( -12.5 cm) each time it is used. The chamber encloses exactly 1,245 cm2 of sediment surface and encloses a volume of 9.5 liters. The top of the box has a battery powered stirrer (constructed from a diving light) attached to help prevent diffusion gradients in the enclosed water when the flux box is emplaced in the sediment. Two 4-cm-diameter holes are also located on the top of the flux box to allow escape of the air inside the box during insertion into the sediment. After the flux box was positioned in the sediment these two holes were plugged with rubber stoppers. Three septa seated on the top of the flux box allowed extraction of 50mL water samples with a syringe. A small plastic sandwich bag was attached to the side of the flux box to replace water that was withdrawn during sampling and to prevent drawing in pore water or water from outside the box. The flux boxes were sampled every 4 h over a 24-h period before being removed. Fluxes were measured at three locations in the estuary: in the southern portion near the

612

MATISOFF and EAKER

railroad bridge, along the eastern edge near Star Island, and near the sandbar. Fluxes were calculated by multiplying a linear regression of the concentration-time data by the enclosed water volume to sediment surface area ratio of the flux box: F = Vdc Adt

(1)

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100

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where F = dissolved flux (mollm2 /day), V enclosed volume of the flux box (m 3), A = surface area enclosed by the flux box (m2), and dc/dt = the linear regression of the concentration-time data (mollm3 /day). Results for several chemical species for September and October 1988 at the shoreline location near Star Island are given in Table 2. Additional data are presented in Matisoff and Eaker (1989).

Diffusional Fluxes Fluxes estimated from Fickian diffusion require knowledge of the interstitial water concentration gradients at the sediment-water interface. The pore water chemistry was determined at the same locations at which the direct flux measurements were made. Pore water "peepers" were used to acquire the pore water samples. The peepers were constructed from 7-mL plastic vials. One side of the vial was cut away and a 0.2 p. membrane filter paper (Gelman Versapore 2000) glued onto the vial to allow solute exchange between the pore water and the peeper (Brunelle 1984). The vials were submerged and filled with deoxygenated/deionized water in the laboratory. The assembled peepers were kept submerged in the deoxygenated/deionized water during transport to the field. A rigid plastic strip with holes at predetermined intervals allowed the peepers to be inserted into the sediment to their appropriate depths. Two vials were deployed at each sample depth in order to acquire approximately 14 ml of sample. The peepers were left in the sediment for over 30 days to allow ionic equilibration with the pore water (Hesslein 1976). After retrieval, the mud was washed off and the samples transferred to small Nalgene sample bottles for chemical analysis in the laboratory. A typical pore water profile for dissolved reactive silicate is shown in Figure 10. The solute flux across the sediment-water interface was calculated by assuming diffusional trans-

FIG. 10. Soluble reactive silicate in sediment pore waters from Old Woman Creek (data from Matisoff and Eaker 1989).

port according to Fick's Law (Ullman and Aller 1980, 1982; Berner 1980): jj = cp DidC j /dx)lx~o

(2)

where jj = the mass of solute i per unit area of sediment per time; Cjis the mass of solute i per unit volume of porewater; x is the space coordinate (positive downward into the sediment); and cp is the porosity of the sediment (cp =0.37, Buchanan 1983). The sediment diffusion coefficient, D sj , was estimated from free ion diffusion coefficients reported by Li and Gregory (1974) and Wollast and Garrels (1971) by a method described by Ullman and Aller (1982) which relates the sediment diffusion coefficient to the product of the free ion diffusion coefficient and porosity. The concentration gradient at the sediment-water interface was found by fitting the pore water data to an exponential decay curve of the form: Y = A-B exp(-Cx), where Y is the concentration at any given depth (x = 0 at the sediment-water interface) and A, B, and C are constants which were fit to the equation by nonlinear least square estimation using the quasiNewton method (Draper and Smith 1981). Diffusional fluxes were calculated from the pore water profiles obtained in March, 1989 at the shoreline location near Star Island and are listed in Table 2. Additional pore water data and solute flux calculations are presented in Matisoff and Eaker (1989) and Frizado et al. (1986). Seepage Fluxes There have been a few recent studies in which groundwater seepage into lakes was measured. Lee et al. (1980) injected a salt solution in a vertical zone between 1.7 and 3 m beneath the shoreline. Their results showed that prediction of solute flux from

SEDIMENT CHEMISTRY AT OLD WOMAN CREEK

onshore zones of groundwater contamination requires consideration of dispersion (mixing) and the ratio of horizontal to vertical permeability. The chemical load brought by groundwater to lakes and estuaries has been estimated from analysis of spring water (Valiela et al. 1978). Enell (1982) demonstrated that groundwater inflow is significant in keeping Lake Bysjon (Sweden) phosphorous concentrations high. Gaudet and Melack (1981) found that groundwater seepage into the NE and NW portions of Lake Naivasha (East Africa) and seepage from the Sand SE portions of the lake into groundwater is significant in controlling the water and chemical mass balances of the lake. Brock et al. (1982), working in Lake Mendota, Wisconsin, where groundwater seepage is known to be an important factor in the hydrological budget, utilized pore water data to examine nutrient loading from groundwater seepage. They found that the groundwater was acting as a source for phosphorous and ammonia and that the nitrate is apparently being removed from the groundwater by denitrification prior to discharge into the lake. We have measured groundwater recharge through the bottom of Lake Chad and have found that this seepage removes as much as 18070 of the annual water input and 160070 of the annual salt input to the lake (Isiorho and Matisoff 1990). Because the barrier sandbar periodically closes the outlet from Old Woman Creek, the water level in the estuary would be expected to rise and seepage through the barrier sandbar becomes the main water and solute transport mechanism between the estuary and Lake Erie. Recently, we measured seepage velocities across the sandbar and at other locations in Old Woman Creek Estuary and have compared solute exchange calculated from diffusional fluxes and seepage measurements (Matisoff and Eaker, 1989). Seepage meters (Fig. 11) were used to measure the time rate of water flux across the sediment-water interface. The method utilizes an open-bottom container (seepage meter) and recording the change of water volume per time in a flexible collection bag attached to the container. This method has been used successfully by many authors to determine seepage between groundwaters and surface waters (Lee 1976, 1977; Lee and Hynes 1979; John and Lock 1977; Lock and John 1978; Downing and Peterka 1978; Fellows and Brezonik 1980; Lee et al. 1980; Connor and Belanger 1981; Gaudet and Melack 1981; Brock et al. 1982; Vanek 1984; Labaugh and Winter 1984; Winter 1986; and Isiorho and Matisoff 1990). The seepage meters

613

----r-----------i Plastic "T'

Tygon Tube

Water Level

Clamp

1

C,llection Bag

55 Gallon Steel Drum

I

1 1

20 cm

1------51.6

cm----~

FIG. 11. Schematic diagram of seepage meter constructed from a 20 cm length at the end of a 55 gallon steel drum (after Isiorho 1987).

used in this study were designed to enable measurement of water flux in either direction across the sediment-water interface. They were constructed from a 30 em section of the top or bottom of a 55 gallon steel drum (Fig. 11). A 6 em diameter hole was drilled into the top of the meter to allow air to escape during emplacement. After the drum was slowly pushed into the sediment, it was allowed to sit for approximately 15 minutes. It was then plugged with a size 13 or 14 rubber stopper/ collection bag. A smaller hole in the rubber stopper contained a 3/8" diameter PVC "T." Two 10 cm long sections of flexible tubing were connected to the "T." A collection bag (1,000 mLlV bag) was attached to one of the pieces of tubing while the other piece of tubing was used for venting any air that became entrapped in the tubing during emplacement. Both pieces of tubing contained a clamp so that only one piece of tubing was opened to the drum at a time. The same procedure was used when measuring the flow from the beach bar into Lake Erie, except that the collection bag was filled with 1,000 mL of water. After 10 minutes the amount of water in the collection bag was remeasured. When measuring the input to Lake Erie from the lake side of the sandbar the collection bag was filled with 100 mL of water and allowed to fill with inflowing water for 10 min. Measurements could not be performed during occasional intense wave action in Lake Erie. Therefore only a few measurements were performed at one location during calm water on the lake side of the sandbar. For measuring the groundwater input to the estuary the bags were filled with 500 mL of water and left undisturbed for 2-6 h before their removal and measurement. Seepage measurements were made at 14 different locations along the barrier beach and at 6 locations in the southern portion of the estuary. The seepage veloc-

614

~

-

MATISOFF and EAKER 14.4 .6 0 14 . 2

0.2

I

E

o

,

I

~

.~ CI>

()

IX' "

I

,,

I

13.8

,I

:I:

0.1

,,

I

~ 13.6

as "

Q)

O~---r---~----,r----,

o

100

FIG. 12. Groundwater discharge (seepage) velocities from Old Woman Creek Estuary into Lake Erie across the barrier sand bar. Data from 13 June 1988.

ity can be calculated from the volumetric time rate of change of water in the bag: dV A dt

=--

3

"0~

/

1IC 0

13.2 May

June

July

Aug

Sept

Oct

Nov

200

Distance from shore (feet)

v

I

I

C!l 13.4

>

I

(3)

where v is the seepage velocity (m/day), A is the surface area covered by the meter (m 2), dV is the change in volume (m 3), and dt is the elapsed time interval (day). Groundwater discharge velocities along the barrier sandbar at Old Woman Creek calculated from seepage measurements ranged from -0.007 mid (recharge to the estuary from Lake Erie) to 1.8 ml d. The average seepage velocity is greatest along the beach edge and decreases exponentially towards zero away from the shore (Fig. 12). This is in agreement with the results of Lee (1977) and Lee et al. (1980) who demonstrated that extrapolations from nearshore sediments predict much lower rates of groundwater flow farther from shore (Cornett et al. 1989). During the summer of 1988 a drought reduced the estuary level from an average gauge height of 14.21 feet in May to 13.36 feet in August after which the drought receeded. From Darcy's Law, the seepage velocity is related to differences between the water levels of the estuary and of Lake Erie. The lower level in the estuary during the summer drought resulted in a reduced head difference and consequently a lower flow through the beach (Fig. 13). A winter storm breached the barrier beach in December, 1988, so that seepage was no longer the main process of water transport between

FIG. 13. Average gauge height of Old Woman Creek Estuary water level and measured groundwater discharge (seepage) velocities through the barrier beach into Lake Erie, May-November 1988.

the estuary and Lake Erie at that time. Seepage measurements were also conducted in the southern portion of the estuary from July through October, 1988, and ranged from 0-0.038 mid into the estuary. The fluxes of solutes across the sedimentwater interface can be calculated as the product of the seepage velocity and the chemical concentration in the water at the sediment water interface (and are given in Table 2 for one location along the eastern edge of the estuary near Star Island). Discussion The estimated solute fluxes across the sedimentwater interface are compared in Table 2. In general, direct measurements using flux boxes produced fluxes that were one to three orders of magnitude higher than fluxes calculated from the pore water profiles or seepage meters. These differences are due to the fact that the different methods are measuring different fluxes. The flux box measures the total flux across the sediment-water interface and its value is dominated by rapid reactions that occur directly at the interface. The pore water profiles measure the concentration differences between the pore waters and the overlying waters and provide an estimate of a longer-term flux associated with sediment burial. The seepage meter fluxes do not measure chemical changes per se, but instead calculate the solute transport associated with the vertical component of groundwater advection. The results presented in Table 2 indicate that the diffusional flux is usually virtually insignificant compared to the seepage flux, and that the seepage

615

SEDIMENT CHEMISTRY AT OLD WOMAN CREEK

'.

-

~ ..b. CHR

~~~

UC / AMP

--

..'

.

. r-_

. ,'.'

;

". <. ...

. ...

.. ' .'~...

~. ~

.. "'.

: ' ..; . ':':"'r

':,'

.,,'

....

FIG. 14. Life positions of dominant profundal freshwater macrobenthos. AMp, Amphipods; CHR, chironomids; TO, tubificid oligochaetes; UC, unionid clams. (from Fisher 1982).

flux is insignificant compared to the values obtained by direct measurements using flux boxes. This general pattern of method-specific estimates of fluxes is not true for calculated values of the silica flux. Decreases in the flux of silica in the winter are due to a seasonal drop in temperature accompanied by a decrease in fresh diatom debris at the sediment surface. As a result, there is significantly less dissolution of diatom frustules at the sediment surface which results in significantly lower silica fluxes determined by the flux box method. In addition, there is less infaunal sediment reworking by chironomids in the winter which also reduces silica flux. Thus, diffusion of silica across the sediment-water interface is the most important factor during the winter months. The importance of infaunal benthos on solute transport cannot be ignored. Figure 14 illustrates the major benthic macroinvertebrates in Lake Erie. Not shown, but perhaps a future important specie on hard substrates is the zebra mussel (Dreissena polymorpha) which is a recent invader from Europe. The mayfly nymph, Hexagenia sp., was an important specie before the 1960s, and may

become important again if the water quality in the western portion of Lake Erie improves. The dominant benthos shown are amphipods, chironomid larvae, tubificid oligochaetes, and unionid clams. Each type of benthos influences solute transport in different ways (Fisher 1982). During our study at Old Woman Creek we observed population densities ranging from 104 indiv. m- 2 to 105 indiv. m- 2 for the oligochaetes and 4,585 indiv. m-2 to 16,811 indiv. m- 2 for the chironomids. We have shown (Matisoff et al. 1985) that chironomids greatly increase the flux of silica from sediments while at the same time they decrease pore water concentrations which leads to low diffusional flux estimates (Fig. 15). Pfister and Frea (1989) examined the downward transport of dissolved cadmium from the water column into Old Woman Creek sediments. In their experimental study, they sequentially added cadmium to the overlying water column and monitored its disappearance in the water over a period of about 2 weeks (Fig. 16). They found that cadmium was removed most effectively after the first addition and least effectively after the third addi-

616

MATISOFF and EAKER

[ H4Si04 ] J,lM 0

400

800

1200 0

400

0

800

-

().-

1200 0

400

800

1200

-€I

'o,

Control

-~ 0

10

-

,, , ,,

~

::r

a

........

(

I

With 'fubifieids

...n

Clams r= 5cm

I

Q

With Chironomids

20

•

Clams r = 10.5 em

Control

30

FIG. 15. Pore water soluble reactive silicate concentration profiles in microcosms with and without benthos. Radial distances are measured from the center of a 2.5 cm radius clam burrow; r = 10.5 cm approximates a control. Note that benthos greatly increase the flux of silica from sediments while at the same time they decrease pore water_ concentrations (from Matisoff et at. 1985).

tion. They found that cadmium transport is enhanced by the microbenthos (bacteria) resulting in downward transport of cadmium to a depths approaching 24 cm in 4 weeks, and that the sedimen microorganisms were conditioned to have increased resistance to the addition of cadmium. SOLUTE BUDGETS AND MODELS One of the major objectives of scientific research in estuaries is to provide the foundation for proper wetlands management. Management considerations include providing water for municipal, commercial, industrial, agricultural, and recreational consumptive uses as well as allocating sufficient water for natural uses such as sustaining habitats and productivity. In addition to water, nutrients and other dissolved solutes and sediments and their associated chemical species have significant impacts on estuaries and estuarine production and

need to be understood in order to properly manage the ecosystem. The quantity and nature of sediments and chemicals delivered to the estuary are greatly influenced by anthropogenic activities in the watershed. Thus, effective management requires both knowledge of the internal processes of the estuarine ecosystem and its response to outside stresses as well as a modeling capability which permits evaluation of the potential changes in the system in response to these internal processes and outside stresses. A hydrologic budget of the estuary is a necessary first step in developing predictive models capable of addressing management questions. Simplified hydrologic and solute budgets were presented in Matisoff and Eaker (1989) and are shown in Figure 17. A hydrologic model was developed by Mitsch and Reeder (1989) and is presented in Figures 18 and 19. In addition, Mitsch discusses systems modeling in this volume. Matisoff and Eaker's budget

SEDIMENT CHEMISTRY AT OLD WOMAN CREEK

617

2.0 to.

\'" ,\

c:

1st dose 2nd dose 3d dose

,\

E

,\ '......

,\

::;)

",

0 ()

...

...

......

Ql

--:, ..........

<'ll

"'\ .....

~

....

.

\

1.0

c:

...... E c. c. ......

.....

"

0

........

"0 ()

--

..... ::>"

0-4-...,..-_-"T"'""-r----,.-----,-~-....,...-..,

o

4

2

6

8

Days After Cd Addition

FIG. 16. Removal of dissolved cadmium from the water column by downward transport into Old Woman Creek sediments. Two weeks between each Cd dose (after Pfister and Frea 1989).

Precipitation 0.32cfs

?

!

Lake Erie

?

Old Woman Creek

l~e,ocity= 0-7 em/sec ?

Evapotran spiration

Estuary 4.4E6 ft3

Flow Disc harge

Ca-1.9E8 Mn-1.2E6 Si-3.7E6 HC03-3.7E8 I: !I: alO

;l;

""<> 1:<1>

:l> 0""

i;<

0

'" U

;

I

0

...N 0

?

?

Seepage Discharge Flux

CI~1.9E8

Sediment Flux Ca=2.19E9 Mn-8.2E8 Si-3.9E9 HC03-4.6E9 C'-O

FIG. 18. STELLA modelfor Old Woman Creek Estuary showing hydrology and productivity submodels. Phosphorus submodel not shown (from Mitsch and Reeder 1989).

'iii 0

0.

"

?

0.076 =0.42 cts Ca-1. 8E8 Mn-2. 3ES Si-2. 9E6 HC03 -3.6E8 C'-S.8 E8

SEDIMENT Ca=1.09E9 Mn-1.86E7 Si-4.4E7 HC03-2.72E9 CI-S.S4E8

FIG. 17. Hydrologic and chemical budgets for Old Woman Creek Estuary. Units for Ca+ +, HC0 3-, and Ct are moles/year (fluxes) and moles (reservoirs). Units for Mn+ + and H,pSi04 are millimoles/year (fluxes) and millimoles (reservoirs). Chemical fluxes calculated from direct flux measurements from April through September. October through December fluxes and seepage fluxes were insignificant. An estuary area of 40 hectares is used to calculate total fluxes (data from Matisoff and Eaker 1989).

is based on a time period when the estuary mouth was closed by the sandbar. Groundwater input occurs around the perimeter of Old Woman Creek Estuary. The lower range of the values (- 0 cfs) occurred during the summer of 1988 when drought conditions prevailed. In September, 1988, the drought conditions began to recede and groundwater input increased (- 2.4 cfs). Discharge through the barrier sandbar ranged from 0.076 cfs to 0.42 cfs from June, 1988, through December, 1988. This barrier sandbar is the major parameter regulating the water level in Old Woman Creek and in the exchange of water and solutes between the estuary and Lake Erie. This can be seen in Figure 19, where Mitch and Reeder (1989) demonstrate that the water level of the outflow can be seen to be strongly coupled to the presence or absence of the barrier sandbar. Their model also indicates that the majority of water leaves the estuary when the sandbar has been breached. The effects of this rapid

618

MATISOFF and EAKER a

between an estuary that is open to Lake Erie or closed by a barrier sandbar. They note that a properly validated model can be used in the future to predict nutrient dynamics of the wetland for a variety of scenarios, including high and low lake levels and differing inputs of water and nutrients from the upstream watershed.

Old Woman Creek Water Level· Field Data

~~

4.2

m ~.O

3.8

129

197

265

4.70

Old Woman Creek Waler Level. Model Results

FUTURE RESEARCH

~_.tO

m ~.IO

380

3.50 61 200,000

100.000 m3/day

00

open 1.00

I~I

130

198

267

335

198

267

335

owe Outnow

opn 10 lake

closed 0.0 61.0 3.20

2.40

mg-pn

Total Phosphorus

1.60

0.800

335

FIG. 19. Data and STELLA model results at Old Woman Creek Estuary in 1988 for water level, surface outflow, and total phosphorus. Range bars indicate one standard deviation of field data (from Mitsch and Reeder 1989).

draining of the estuary have not been studied, but their model results indicate that significant differences related to the state of the sandbar may occur in the total phosphorous and sedimentation rates. However, their model does not calculate major differences in the gross primary productivity, chlorophyll a, macrophyte biomass, or resuspension rates

Perhaps the most visible aspect of the research at Old Woman Creek is that it is conducted by independent workers on independent projects occurring at different times. Although this method of research is likely to provide quality work within individual disciplines, it provides an uncoordinated data base and research base at the estuary. Simply put, one or two funded research projects per year will not lead to a comprehensive understanding of the system. A long-term, focussed study encompassing all aspects of the ecosystem at the estuary with each of the various researchers working at the same time, in the same locations, and sharing a common database is needed before accurate models can be constructed and a validated management plan can be developed and implemented. Perhaps the conference and this special issue can serve as a guide to developing a proposal to support a research program of that type at Old Woman Creek. Future efforts are needed in other areas as well. Additional case studies at other wetlands/estuarine environments in Lake Erie and in the other Great Lakes are needed. An understanding of the major controls on the ecosystem is sometimes best pursued by comparing and contrasting different sites. The role of storms on the estuarine ecosystem and on the physical and chemical transport of pollutants and nutrients needs considerably more detailed study. The impact of human activities within the watershed and within the estuary are not understood, and a reconstruction of the historical record from bottom sediments will assist in this task. Specifically with respect to sediment studies it is necessary to determine the annual time series of the influx and efflux of sediment, nutrients, metals, and toxicants; quantitatively determine the role of various sized storms and waves on the budgets; determine the seasonality of these fluxes and relate them to precipitation and human activity in the watershed and to water levels in the estuary and in Lake Erie; identify the role of Lake Erie water as a

SEDIMENT CHEMISTRY AT OLD WOMAN CREEK

source or sink in the sediment, nutrient, metal, and toxicant budgets; determine the nature and rate of movement of sediment through the estuary; determine the location and rates of sediment deposition within the estuary; determine the nature, location, and effects of waves and storms on the chemical interactions of suspended sediments, sediment pore waters, and estuarine waters; determine the effects of periodic dessication on the physical, chemical, and biological properties of the sediment; determine the nature, location, and effects of waves and storms on the macrobenthic and meiobenthic community of the estuarine sediments; determine the roles of macrobenthos and meiobenthos on material transport across the sediment-water interface and on vertical transport within a buried sediment column; determine the effects of rooted aquatic vegetation on sediment transport and accumulation; and determine the effects of rooted aquatic vegetation on sediment chemistry and biology and on mass transport across the sediment-water interface. Upon collection and interpretation of this type of data it may then be possible to address some of the more general future objectives in the development of a validated management plan. REFERENCES Aller, R.C. 1978. The effects of animal-sediment interaction on geochemical processes near the sedimentwater interface. In Estuarine Interactions, ed. M.L. Wiley, pp. 157-172. New York: Academic Press. _ _ _ _ . 1980. Quantifying solute distributions in the bioturbated zone of marine sediments by defining an average microenvironment. Geochim. Cosmochim. Acta 44:1955-1965. _ _ _ _ . 1982. The effects of macrobenthos on chemical properties of marine sediment and overlying water. In Animal-Sediment Relations: The Biotic Alteration of Sediments, eds. P.L. McCall and M.J.S. Tevesz, pp. 53-102. Plenum. Baker, D.B. 1985. Regional water quality impacts of intensive row-crop agriculture: Lake Erie basin case study. J. Soil Water Conserv. 40:125-132. Berner, R.A. 1974. Kinetic models for the early diagensis of nitrogen, sulfur, phosphorous and silicon in anoxic marine sediments. In The Sea, Vol. 5, Marine Chemistry, ed. B.D. Goldberg, pp. 427-450. Wiley. _ _ _ _ . 1980. Early Diagenesis: A Theoretical Approach. Princeton University Press. Boyle, E., Collier, R., Dengler, A.T., Edmond, J.M., Ng, A.C., and Stallard, R.F. 1974. On the chemical mass balance in estuaries. Geochim. Cosmochim. Acta 38:1719-1728.

619

Bradford, W.L. 1972. A study on the chemical behavior of zinc in Chesapeake Bay water using anodic stripping voltammetry. Chesapeake Bay Institute, Tech. Rept. 76, Ref 72-7, Johns Hopkins University, Baltimore, Md. Brock T.D., Lee, D.R., Janes, D., and Winek, D. 1982. Groundwater seepage as a nutrient source to a drainage lake; Lake Mendota, Wisconsin. Water Res. 16:1255-1263. Brunelle, T.M. 1984. Non-steady state sulfur diagenesis in softwater lakes: An initial investigation. M.S. thesis, The University of Rochester, Rochester, New York. Buchanan, D.B. 1983. Transport and deposition of sediment in Old Woman Creek Estuary, Erie County, Ohio. M.S. thesis, Ohio State University, Columbus, Ohio. Cambell, L.J. 1955. The lake glacial and lacustrine deposits of Erie and Huron Counties, Ohio. Ph.D. dissertation, Ohio State University, Columbus, Ohio. Connor, J.N., and Belanger, 1981. Groundwater seepage in Lake Washington and the upper St. John's River basin, Florida. Water Resour. Res. 3:263-269. Cornett, R.J., Risto, B.A., and Lee, D.R. 1989. Measuring groundwater transport through lake sediments by advection and diffusion. Water Resour. Res. 25:1815-1824. Cronin, L.E., 1975. Estuarine Research. Vol II. Geology and Engineering. New York: Academic Press, Inc. Downing, J.A., and Peterka, J.J. 1978. Relationship of rainfall and lake groundwater seepage. Limnol. Oceanogr. 21 :912-914. Draper, N., and Smith, H. 1981. Applied Regression Analysis, 2nd Ed. New York: John Wiley and Sons. Dyer, K. 1990. the rich diversity of estuaries. Estuaries 13:504-505. Enell, M. 1982. The phosphorous economy of a hypertrophic seepage lake in Scania, South Sweden groundwater influence. Hydrobiologia 86:153-158. Fellows, C.R., and Brezonik, P.L. 1980. Seepage flow into Florida Lakes. Water Res. Bull. 16-4: 635-644. Fisher, J.B. 1982. Effects of macrobenthos on the chemical diagenesis of freshwater sediments. In Animal-Sediment Relations: The Biotic Alteration of Sediments, eds. P.L. McCall and M.J.S. Tevesz, pp. 177-218. Plenum. Frank, R., Braun, H.E., van Hove Holdrine, M., Sirons, G.J., and Ripley, B.D. 1982. Agriculture and water quality in the Canadian Great Lakes Basin: V. Pesticide use in 11 agricultural watersheds and presence in stream water, 1975-1977. J. Environ. Qual. 11:497-505. Frizado, J., and Anderhalt, R., Mancuso, C., and Norman, L. 1986. Depositional and diagenetic processes in a freshwater estuary. Final Report submitted to Sanctuary Programs Division, NOAA and Ohio De-

620

MATISOFF and EAKER

partment of Natural Resources, Division of Natural Areas and Preserves. Gaudet, J.J., and Melack, M.J. 1981. Major ion chemistry in a tropical African lake basin. Freshwater Biology 11 :309-333. Herdendorf, C.E. 1963. The geology of the Vermillion Quadrangle, Ohio. M. S. thesis, The Ohio State University, Columbus, Ohio. _ _ _ _ . 1966. Geology of the Vermilion West and Berlin Heights quadrangles, Erie and Huron Counties, Ohio: Ohio Geological Survey Report of Investigations 60. _ _ _ _ . 1990. Great Lakes estuaries. Estuaries 13:493-503. Hesslein, R.H. 1976. An in situ sampler for close interval pore water studies. Limnol. Oceanogr. 21:912-914. Holdren, G.R., Brunelle, T.M. Matisoff, G., and Wahlen, M. 1984. Timing the increase in atmospheric sulphur deposition in the Adirondack Mountains. Nature 311:245-248. International Joint Commission, 1978. Environmental management strategy for the Great Lakes system. Final Report from the Pollution from Land Use Activities Reference Group (PLUARG). Windsor, Ontario. _ _ _ _ . 1980. Post-PLUARG evaluation of Great Lakes water quality management studies and programs. Vol.2 Windsor, Ontario. Isiorho, S.A. 1987. The interactions between Lake Chad and the phreatic aquifer in the southwest Chad basin. Ph.D. dissertation, Case Western Reserve University, Cleveland. _ _ _ _ , and Matisoff, G. 1990. Groundwater seepage from Lake Chad. Limnol. Oceanogr. 35:931-938. John, P.H., and Lock, M.A. 1977. The spatial distribution of groundwater discharge into the littoral zone of a New Zealand lake. J. Hydrology 33:391-395. Kennedy, V.S. 1984. The Estuary as a Filter. New York: Academic Press. Klarer, D. 1988. The role of a freshwater estuary in mitigating storm water inflow. Old Woman Creek Technical Report Number 5. Ohio Department of Natural Resources, Division of Natural Areas and Preserves. Labaugh, J.W., and Winter, T.C. 1984. The impact of uncertainties in hydrological measurements on phosphorous budgets and emperical models for the Colorado reservoirs. Limnol. Oceanogr. 29:322-339. Lee, D.R. 1976. The role of groundwater in the eutrophication of a lake in glacial outwash terrain. Intern. J. Speleology 8:117-126. _ _ _ _ . 1977. A device for measuring seepage flux in lakes and estuaries. Limnol. Oceanogr. 25:183-186.

_ _ _ _ , and Hynes, H.RN. 1977. Identification of groundwater discharge zones in a reach of Hillman Creek in Southern Ontario. Water Pollut. Res. Bd. Can. 13: 140-147. _ _ _ _ , Cherry, J.A., and Pickens, J.R. 1980. Groundwater transport of salt tracer through a sandy lake bed. Limnol. Oceanogr. 25:45-61. Lerman, A., and Jones, RF. 1973. Transient and steady-state transport between sediments and brines in closed lakes. Limnol. Oceanogr. 18:72-85. Li, Y., and Gregory, S. 1974. Diffusion of ions in seawater and in deep-sea sediments. Geochim. Cosmochim. Acta 38:703-714. Lock, M.A., and John P.H. 1978. The measurement of groundwater discharge into a lake by a direct method. Intern. Revue Gesamenten Hydrobiologie 63:271-275. Logan, T.J. 1982. Mechanisms for release of sedimentbound phosphate to water and the effects of agriculturalland management of fluvial transport of particulate and dissolved phosphate. Hydrobiologia 92:519-530. _ _ _ _ .1987. Diffuse (non-point) source loading of chemicals to Lake Erie. J. Great Lakes Res. 13:649-658. Martens, C.S., and Burdige, J.D. 1988. Biogeochemical cycling in an organic rich coastal marine basin: 10. The role of amino acids in sedimentary carbon and nitrogen cycling. Geochim. Cosmochim. Acta 52:1571-1584. Matisoff, G. 1982. Mathematical models of bioturbation. In Animal-Sediment Relations: The Biotic Alteration of Sediments, P.L. mcCall and M.J. Tevesz, eds., pp. 289-330. Plenum. _ _ _ _ , and Eaker, J. 1989. The importance of groundwater advection on sediment-water chemical exchange at Old Woman Creek freshwater estuary. NOAA Final Report #NA88AA-D-CZ-012. _ _ _ _ , Lindsay, H., Matis, S., and Soster, F. 1980. Trace metal mineral equilibrium in Lake Erie sediments. J. Great Lakes Res. 6:353-366. _ _ _ _ , Fisher, J.B., and McCall, P.L. 1981. Kinetics of nutrient and metal release from decomposing lake sediments. Geochim. Cosmochim. Acta 45:2333-2347. _ _ _ _ , Fisher, J.B., and Matis, S. 1985. Effects of benthic macroinvertebrates on the exchange of solutes between sediments and freshwater. Hydrobiologia 122:19-33. Mitsch, W.J., and Reeder, B.C. 1989. Ecosystem modelling of a Lake Erie Coastal WEtland. In Wetlands of Ohio's Coastal Lake Erie: A Hierachy of Systems, ed. W.J. Mitsch. Ohio Sea Grant R/ER-13-PD. Nixon, S.W. 1990. Toward a broader definition of estuaries? Estuaries 13:492. Nriagu, J.O., Kemp, A.L.W., Wong, J.K.T., and Harper, N. 1979. Sedimentary record of heavy metal

SEDIMENT CHEMISTRY AT OLD WOMAN CREEK pollution in Lake Erie. Geochim. Cosmochim. Acta 43:247-258. Odum, W.E. 1990. The lacustrine estuary might be a useful concept. Estuaries 13:506-507. Pepper, J.P., deWitt Jr., W., and Demarest, D.F. 1954. Geology of the Bedford Shale and Berea Sandstone in the Appalachian Basin. U.S. Geological Survey Professional Paper 259. Pfister, R.M., and Frea, J.1. 1989. Relationship of toxic metals and bacteria in sediments of Old Woman Creek Estuary. NOAA N.E.R.R.S Final Report. Richards, R.P., and Baker, D.B. 1985. Assimilation and flux of sediments and pollutants in the Sandusky River Estuary, Sandusky Bay, and the adjacent nearshore zone of Lake Erie. Final Report submitted to NOAA, Grant #NA80RADOOO38. Schubel, J.R. 1974. Effects of Tropical Storm Agnes on the suspended solids of northern Chesapeake Bay. In Suspended Solids in Water, ed. R.J. Gibbs, pp. 113-132. New York: Plenum Press. _ _ _ _ , and D.W. Pritchard. 1990. Great Lakes estuaries - phooey. Estuaries 13:508-509. Shane, 1982. Personal communication cited in Buchanan (1983). Sharp, J.H., Pennock, J.R., Church, T.M., Tramontano, J.M., and Cifuentes, L.A. 1984. The estuarine interaction of nutrients, organics, and metals: A case study in the Delaware Estuary. In The Estuary as a Filter, ed. V.S. Kennedy, pp. 241-258. New York: Academic Press. Thomann, R.V., and Di Toro, D.M. 1983. Physicochemical model of toxic substances in the Great Lakes. J. Great Lakes Res. 9:474-496. Ullman, W.J., and Aller, R.C. 1980. Dissolved iodine flux from estuarine sediments and implications for the enrichment of iodine at the sediment-water interface. Geochim. Cosmochim. Acta 44:1177-1184. _ _ _ _ , and Aller, R.C. 1982. Diffusion coefficients in nearshore marine sediments. Limnol. Oceanogr. 27:552-556.

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Valiela, I., Teal, J.M., Volkman, S. Schafer, D., and Carpenter, E.J. 1978. Nutrient and particulate fluxes in a salt marsh ecosystem: Tidal exchanges and inputs by precipitation and groundwater. Limnol. Oceanogr. 23:798-812. Vanderborcht, J.P., Wollast, R., and Billen, G. 1977. Kinetic models of diagenesis in disturbed sediments. Part 1. Mass transfer properties and silica diagenesis. Limnol. Oceanogr. 22:787-793. Vanek, V. 1984. Groundwater-lake interaction in a south Swedish lake. Limnologitil/ampningsarbete. Institute of Limnology, University of Lund. Wall, G.J., Dickenson, W.T., and van Vliet, L.J.P. 1982. Agriculture and water quality in the Canadian Great Lakes Basin. II Fluvial sediments. J. Environ. Qual. 11 :482-486. Wiley, M.L. 1978. Estuarine Interaction. New York: Academic Press. Winter, T.C. 1986. Numerical simulation analysis of the interactions of lakes and groundwater. U.S. Geol. Surv. Prof. Paper 1001. Wollast, R., and Garrels, R.M. 1971. Diffusion coefficient of silica in seawater. Nature 229:94. Yaksich, S.M., Melfi, D.A., Baker, D.B., and Kramer, J.A. 1982. Lake Erie nutrient load, 1970-1980. Lake Erie Wastewater Management Study Technical Report, U.S. Army Corps of Engineers, Buffalo, New York. _ _ _ _ , Melfi, D.A., Baker, D.B., and Kramer, J.A. 1985. Lake Erie nutrient load, 1970-1980. J. Great Lakes Res. 11:117-131. Zabawa, C.F., and Schubel, J.R. 1974. Geological effects of tropical storm Agnes on Upper Chesapeake Bay. Maritime Sediments 10:79-84.

Submitted: 20 October 1990 Accepted: 3 June 1992