Island Sound Sediments Research Articles

Low denitrification rates and variable benthic nutrient fluxes characterize Long Island Sound sediments

Organic matter (OM) loading drives benthic metabolism and controls nitrogen (N), phosphorus (P), and carbon (C) cycling in coastal sediments. To better understand the influence of OM on benthic metabolism, we conducted sediment core incubations in Long Island Sound, NY (USA), an estuary heavily influenced by anthropogenic nutrient loading. Cores were collected during the summer and winter at five stations along a west to east transect representing a gradient of high to low nutrient inputs and subsequent OM deposition. Here we provide a comprehensive analysis of environmental drivers of benthic fluxes as well as the first directly measured rates of sediment denitrification and N-fixation, thus providing a missing piece of the N budget for Long Island Sound. Our findings show greatest sediment oxygen demand (SOD) in the western basin during the summer. Sediments were a source of dissolved inorganic N and P. Compared to historic SOD and ammonium fluxes, our measurements were about 50% lower, potentially reflecting larger scale perturbations (e.g., warming temperatures, decrease wind speed) or reduced N loading through improved management of wastewater treatment facilities. Sediments were a source of nitrous oxide (mean (± standard error): 8.63 ± 3.18 nmol m−2 h−1) and methane (23.80 ± 18.05 nmol m−2 h−1). Net sediment denitrification rates were low (10.34 ± 7.61 µmol N2–N m−2 h−1) and did not vary significantly across stations or seasons. These sediments have a N removal efficiency of ~ 30% with the potential to remove approximately 9% of the total land-based N load entering Long Island Sound.

Concentrations of DDTs and dieldrin in Long Island Sound sediment

The concentrations of three frequently detected organochlorine pesticides (OCPs) and one degradation product, p,p'-DDT, p,p'-DDD, dieldrin, and p,p'-DDE were determined in recently collected (2005-2006) and archived (1986-1989) surficial sediments and sediment cores from Long Island Sound (LIS). The concentration of dieldrin ranged from 0.05 to 5.27 ng g(-1) dry weight in the surficial sediments, and from 0.05 to 11.7 ng g(-1) dry weight in the sediment cores. Total DDXs (the sum of p,p'-DDE, p,p'-DDD and p,p'-DDT) concentrations ranged from 1.31 to 33.2 ng g(-1) in surficial sediments and 1.11 to 66.4 ng g(-1) in sediment cores. The results indicate that the three OCPs and DDE were still widely present in LIS surficial sediments two decades after the use of these pesticides in the United States was banned. In addition, the surficial concentrations did not decrease significantly when compared to the concentrations in archived samples collected two decades ago. Sediments in the western part of LIS were more contaminated (with concentrations in some western sites being still above probable effect levels) than those in the eastern part, probably as a result of the net westward sediment transport in LIS. The three OCPs and DDE were detected at all depths (down to ~50 cm) in the sediment cores, and concentration profiles indicated a depositional sedimentary environment with significant sediment mixing. Such mixing may redistribute OCPs deposited earlier (deeper in sediment bed) to the sediment surface and lead to enhanced persistence of OCP concentrations in surficial sediments.

Lack of Enantioselective Microbial Degradation of Chlordane in Long Island Sound Sediment

Numerous studies have examined the enantiomeric compositions of trans- and cis-chlordane in soils (agricultural, background, and house foundation soils) and in the atmosphere. In contrast, little is known aboutthe enantiomeric compositions of chlordane in sediment. In this work, surficial sediments and sediment cores were collected at various sites in Long Island Sound (LIS) previously surveyed by the National Oceanic and Atmospheric Administration's (NOAA) National Status and Trends (NS&T) Program. Archived surficial sediments at selected sites were acquired from the NS&T Specimen Bank. The chlordanes were racemic or nearly racemic in most archived and recently collected sediments, indicating thatthe enantiomeric compositions of the sources of chlordane to LIS sediment did not change in the past two decades, and that house foundation soils are likely the major source of chlordanes to LIS. Invariant enantiomeric compositions temporally in surficial sediments and at different depths in sediment cores clearly indicate the lack of enantioselective biodegradation in LIS sediment, in striking contrast to the widely observed enantioselective biodegradation of chlordanes in soils.

Mercury contamination chronologies from Connecticut wetlands and Long Island Sound sediments

Sediment cores were used to investigate the mercury deposition histories of Connecticut and Long Island Sound. Most cores show background (pre-1800s) concentrations (50–100 ppb Hg) below 30–50 cm depth, strong enrichments up to 500 ppb Hg in the core tops with lower Hg concentrations in the surface sediments (200–300 ppb Hg). A sediment core from the Housatonic River has peak levels of 1,500 ppb Hg, indicating the presence of a Hg point source in this watershed. The Hg records were translated into Hg contamination chronologies through 210Pb dating. The onset of Hg contamination occurred in ~1840–1850 in eastern Connecticut, whereas in the Housatonic River the onset is dated at around 1820. The mercury accumulation profiles show periods of peak contamination at around 1900 and at 1950–1970. Peak Hg* (Hg*= Hg measured minus Hg background) accumulation rates in the salt marshes vary, dependent on the sediment character, between 8 and 44 ng Hg/cm2 per year, whereas modern Hg* accumulation rates range from 4–17 ng Hg/cm2 per year; time-averaged Hg* accumulation rates are 15 ng Hg/cm2 per year. These Hg* accumulation rates in sediments are higher than the observed Hg atmospheric deposition rates (about 1–2 ng Hg/cm2 per year), indicating that contaminant Hg from the watershed is focused into the coastal zone. The Long Island Sound cores show similar Hg profiles as the marsh cores, but time-averaged Hg* accumulation rates are higher than in the marshes (26 ng Hg/cm2 a year) because of the different sediment characteristics. In-situ atmospheric deposition of Hg in the marshes and in Long Island Sound is only a minor component of the total Hg budget. The 1900 peak of Hg contamination is most likely related to climatic factors (the wet period of the early 1900s) and the 1950–1970 peak was caused by strong anthropogenic Hg emissions at that time. Spatial trends in total Hg burdens in cores are largely related to sedimentary parameters (amount of clay) except for the high inventories of the Housatonic River, which are related to Hg releases from hat-making in the town of Danbury. Much of the contaminated sediment transport in the Housatonic River Basin occurs during floods, creating distinct layers of Hg-contaminated sediment in western Long Island Sound. The drop of about 40% in Hg accumulation rates between the 1960s and 1990s seems largely the result of reduced Hg emissions and to a much lesser extent of climatic factors.

Introduction to Mercury Special Issue

This special issue contains 11 papers derived from a topical session titled ‘‘The Impact of Mercury on the Global Environment’’, held in Reno, Nevada, at the 2000 Annual Meeting of the Geological Society of America (GSA). Mercury is of particular concern because of its toxicity, persistence in ecosystems, capacity to bio-accumulate, and global dispersion pattern. The GSA session brought together researchers addressing aspects of this global environmental problem. Topics discussed included natural and anthropogenic sources of mercury, its transport and cycling, the production of methylmercury, and its potential and actual uptake by organisms in mercury-impacted ecosystems. Interest in mercury in the US has been heightened by fish consumption advisories in many states. The 1990 amendments to the US Clean Air Act (CAA) identify mercury as one of several, potentially hazardous air pollutants. Subsequent reports by the National Academy of Sciences and the USA Environmental Protection Agency (EPA) single out mercury as having the greatest potential to impact human health of any of the pollutants identified in the CAA. In December 2000, the EPA announced it would seek to limit mercury emissions from US coalburning power plants, the only major anthropogenic point source not currently regulated. This determination was made after EPA analysis of weekly data on mercury contents in feed coals, and on the quantity and speciation of mercury in stack emissions, collected for US power plants during the1999 calendar year. This special issue includes an analysis by Quick et al. (DOI 10.1007/s00254-002-0622z) of the mercury content of US coals delivered to power plants, based on the EPA results. The behavior of mercury in wetlands and aquatic ecosystems is another important topic addressed in the GSA session and in this special issue. The paper by Marvin-DiPasquale et al. (DOI 10.1007/s00254-002-0623-y) determines rates of methylation and microbial cycling of mercury in San Francisco Bay sediments impacted by Gold Rush-era hydraulic mining debris. In the paper by Varekamp et al. (DOI 10.1007/s00254-002-0624-x), the authors show the chronology of mercury deposition in Connecticut wetlands and Long Island Sound sediments locally impacted by anthropogenic mercury sources. The study by Loukola-Ruskeeniemi et al. (DOI 10.1007/s00254002-0625-9) goes a step further, considering potential uptake of mercury from black shales by lakes and lake sediments, crayfish, fish and, ultimately, human residents of an area in eastern Finland. Several papers in this issue discuss the impact of mercury derived from past and present mining activities. Gray et al. (DOI 10.1007/s00254-002-0626-8) studied dispersion of mercury and methylmercury from an abandoned mercury mine in the Philippines, in close proximity to coastal settlements where residents consume a high proportion of fish and other seafood. Drude de Lacerda (DOI 10.1007/ s00254-002-0627-7) estimates the amount of mercury used worldwide in small-scale gold-refining operations. Papers by Rytuba (DOI 10.1007/s00254-002-0629-5), Miller and Lechler (DOI 10.1007/s00254-002-0628-6), and Gustin et al. (DOI 10.1007/s00254-002-0630-z) consider potential mercury sources, transport and cycling of mercury, and its atmospheric dispersal, respectively, as a result of historic gold mining or mercury mineralization. The papers by Abbott et al. (DOI 10.1007/s00254-0020631-y) and Susong et al. (DOI 10.1007/s00254-002-0632x) are important case studies of point-source mercury emission by a fluidized bed thermal-treatment calciner at Idaho National Engineering and Environmental Laboratory. These studies consider mercury deposition in soils and its potential re-emission from soils to the atmosphere, resulting from an atmospheric source whose mercury emission rate and operational parameters are known. The papers included in this special issue are illustrative of the complex nature of mercury dissemination in the environment. Understanding mercury dispersion and Received: 27 November 2001 / Accepted: 11 January 2002 Published online: 26 June 2002 a Springer-Verlag 2002

Formation of artifact methylmercury during extraction from a sediment reference material.

We examined monomethylmercury (MMHg) in sediment reference material IAEA-405 and sediments from Long Island Sound. MMHg was extracted by both aqueous distillation and leaching with dilute solutions of nitric acid. MMHg was formed from both ambient and added inorganic mercury in extracts of IAEA-405 by either technique. Artifact MMHg in IAEA-405 was related linearly with ambient reactive mercury (HgR) in leachates having > 1.2 M acid, but little or no artifact was measured in less acidic extracts. Addition of potassium chloride enhanced extraction of HgR from LAEA-405 but had no effect on artifact MMHg for each leachate molarity tested. Mercury methylation occurred in solution and was a function of both the availability of HgR and a methylation potential, being limited by HgR in less acidic solutions (0.5-1.2 M) and by the methylation potential in more acidic ones (> 1.2 M). Formation of artifact MMHg in Long Island Sound sediments was inconclusive, but additions of inorganic mercury demonstrated that a potential exists. A potential for abiotic mercury methylation seems always present in sediment, and the availability of HgR appears to control MMHg production under environmental conditions. Abiotic methylation of mercury may occur in environs where the reactivity of inorganic mercury is enhanced, such as river-seawater mixing zones.

Early diagenesis of calcium carbonate in Long Island Sound sediments: Benthic fluxes of Ca<SUP>2+</SUP> and minor elements during seasonal periods of net dissolution

The present study confirms the quantitative significance of carbonate dissolution for associated major and minor element solute fluxes in shelf deposits of temperate regions. Multiple measurement techniques all demonstrate that net dissolution of CaCO 3 dominates during winter in Long Island Sound sediments and results in large fluxes of Ca 2+ , Sr 2+ , and F - out of the seafloor. Ca 2+ fluxes averaged from 4 independent methods range from ∼5 to ∼13 mmol m -2 d -1 with highest flux occurring when surface deposits are most undersaturated with respect to common biogenic carbonates. A significant proportion of dissolution, 40-100%, results from oxidation of reduced metabolites such as FeS, NH + 4 , and Mn 2+ . Results suggest that 90% of the CaCO 3 precipitated each year is dissolved, equivalent to a loss of ∼90-190 g CaCO 3 m -2 yr -1 . Given the general similarity between Long Island Sound and other muddy coastal estuaries along the eastern coast of North America and elsewhere (e.g. Chesapeake Bay, Delaware Bay, Narragansett Bay, Buzzards Bay, Casco Bay), these relative flux measurements are likely to be indicative of much larger temperate regions.

Molecular weight distribution of proteinaceous material in Long Island Sound sediments

Proteinaceous material usually accounts for much of the total nitrogen and organic carbon in marine sediments. Thus, decomposition of protein is frequently investigated as a measure of labile organic matter turnover. The fraction of protein that escapes remineralization to CO2 undergoes transformations that may reflect pathways of preservation in sedimentary environments. We analyzed the molecular weight distribution of sedimentary proteinaceous material extracted with NaOH and evaluated the results in terms of diagenetic changes experienced by this pool. Total protein concentrations were determined in Long Island Sound sediments as total hydrolyzed amino acids (THAA), the sum of concentrations of individual amino acids measured after acid hydrolysis. Although the total fraction of THAA extracted by NaOH decreases slightly downcore, from 55% to 40%, the molecular size of that THAA increases. Proteinaceous material >100 kD increases in relative importance with depth and age of sediment, reaching 70% of the total THAA pool at 3 m depth, or roughly 1,000 yr of sediment accumulation. The fraction of THAA between 10 and 100 kD decreased from 25% to 5% of the total over this depth. The relative abundance of the peptide‐size fraction (<3 kD) remained essentially unchanged. The processes of bacterial production, selective adsorption, geo‐polymerization, and selective preservation were explored to explain these changes.

Diagenesis of planktonic fatty acids and sterols in Long Island Sound sediments: Influences of a phytoplankton bloom and bottom water oxygen content

Diagenesis of organic matter in coastal sediments from Long Island Sound (LIS) was investigated by measuring fatty acids and sterols in (1) a time-series of surface sediment samples over a spring phytoplankton bloom; and (2) sediment cores collected during and after a bloom at two sites with distinctively different bottom-water oxygen contents. Time-dependent distributions of sedimentary fatty acids and sterols in LIS were strongly affected by pulsed inputs from the overlying water column, variations in benthic community, and redox-related degradation processes. The phytoplankton bloom delivered an intense pulse of unsaturated fatty acids (e.g., 16:1(ω7) and 20:5) to the surface sediments. Continuous increases of cholesterol and diunsaturated sterols after the bloom were related to zooplankton grazing processes and increase in benthic faunal abundance. High inventories of planktonic fatty acids and sterols in the upper 5 cm sediments were observed at the low oxygen site during summer, probably caused by a combination of higher input, reduced degradation rates and lower macrofaunal activity under anoxic conditions compared to oxic conditions.

Seasonal patterns of carbonate diagenesis in nearshore terrigenous muds: Relation to spring phytoplankton bloom and temperature

Pore water saturation state with respect to calcite and aragonite minerals in Long Island Sound sediments fluctuates from saturated and near saturated conditions during late fall, to undersaturated during winter, before slowly changing to supersaturated conditions during late spring. Undersaturation occurs during cold, winter periods when lower rates of ΣCO 2 production (low rates of heterotrophic metabolism) and oxidation of reduced minerals such as FeS lower calcium carbonate saturation states. Direct evidence that dissolution of both calcites and aragonite are occurring during this season comes from the simultaneous increases in excess pore water carbonate dissolution products Ca 2+ , F - , and Sr 2+ during periods of pore water undersaturation. Higher ΣCO 2 production rates during warmer periods cause the CO 3 2- concentration to become supersaturated for both calcite and aragonite. ΣCO 2 production is controlled by both temperature and substrate availability so that benthic deposition of organic matter produced during the spring bloom accelerates the seasonal progression of pore waters to supersaturation. These patterns control carbonate dynamics in temperate, nearshore regions, and result in a regularly observed, yearly cycling of calcium carbonate dominated by alternating periods of net dissolution and net precipitation.

Transfer rates of dissolved tracers through estuaries based on 228Ra: A study of Long Island Sound

Using 228Ra (half-life = 5.7 y) we have determined the transfer rate of water as the carrier of tracers (dissolved substances) into Long Island Sound from its western boundary. The primary sampling was done in the summer of 1991, with additional sampling of surface waters in the winter and summer of 1992 and the summer of 1993. The ( 228Ra/ 226Ra) activity ratio was determined by γ-spectrometry of Mn-coated fibers through which sea water was passed. An independent measurement of 226Ra activity per liter of sea water via scintillation counting of 222Rn was made at each sampling site. Based on the 228Ra concentrations in Long Island Sound water, water from the western boundary (off Randalls Island near the connection of the East River with the sound) and shelf water entering the sound from the east together with the measured flux of 228Ra from Long Island Sound sediments, we can determine the transfer rate of water from the East River to Long Island Sound during the summer of 1991. This value was between 0.40 × 1014 l y −1 and 1.1 × 10 14 l y −1, depending on the 228Ra flux from sediments used. The corresponding residence time of water in Long Island sound was between 166 and 63 days.

Anoxic and oxic degradation of 14C‐labeled chloropigments and a 14C‐labeled diatom in Long Island Sound sediments

Anoxic and oxic degradation pathways of sedimentary chloropigments were examined by spiking marine sediment with14C‐labeled algal cells and purified chloropigments from the diatom Skeletonema costatum. These experiments suggest that Chl a degrades through multiple pathways. Under oxic conditions, most bulk sedimentary Chl a degraded to various colorless compounds and only a minor fraction degraded to pheophytin a; added 14C‐labeled Chl a also degraded quickly, but 30–40% of this Chl a was converted to pheophytin a. Under anoxic conditions, only a small fraction of bulk Chl a degraded, but added 14C‐labeled Chl a continuously degraded and ~30–40% of it was converted to pheophytin a. Pheophytin a is relatively stable under anoxic conditions but degrades under oxic conditions, thus it is a potential end product of chloropigment degradation in anoxic environments.Degradation pathways are likely dependent on the relative proportion of unassociated Chl a to chlorophyll complexes present in the sediment. Only unassociated Chl a appears to be available for anoxic decomposition. Under oxic conditions, some colorless products were further degraded and solubilized; none of the 14C label added as purified pigments was lost under anoxic conditions during the 1‐month incubation. About 80% of the acetone‐extractable 14C in labeled cells was lost in 1 month from sediments under oxic conditions and ~30% under anoxic conditions.

Laboratory studies of oxic and anoxic degradation of chlorophyll- a in Long Island Sound sediments

Laboratory incubations of Long Island Sound (LIS) sediments show that chlorophyll-a (Chl a) degradation generally follows first-order kinetics, but that the rates and mechanisms of degradation differ under oxic and anoxic conditions. Chl-a in fresh sediment can be operationally defined as being present in three pools: bound Chl- a (nonextractable by acetone), free (acetone extractable) anoxically degradable Chl-a, and free anoxically stable Chl-a. A major pathway of degradation is initial release of bound Chl-a into the free pool. The release rate constants of bound Chl-a into free Chl-a are remarkably faster (> 10×) under oxic (~4 d −1) compared to anoxic (~0.1 d −1) conditions, and a much greater fraction of total Chl-a degrades under oxic conditions. However, the apparent degradation rate constants of free Chl-a are two to three times higher in the absence of oxygen in sediments with high bound Chla (~0.2−0.3 d −1 for anoxic; ~0.1 d −1 for oxic) and about seven times higher in sediments without bound Chl-a (~0.3 d −1 for anoxic; ~0.04 d −1 for oxic). The differences between anoxic and oxic decomposition in incubation experiments, together with naturally observed concentration profiles which reach low levels of Chl-a, imply that Chl-a in natural sediments degrades during the oscillation between oxic and anoxic conditions caused by physical and biological mixing processes. Oscillation experiments (oxic vs. anoxic and anoxic vs. oxic) suggest that the activities of aerobic organisms may be an important factor affecting Chl- a degradation. Examination of effects of meiofauna on Chl- a degradation under oxic conditions implies that microorganisms may play a stronger role in Chl- a degradation than meiofauna (> 0.125 mm). The relative temperature independence of anoxic degradation and temperature dependence of oxic degradation suggest that anoxic degradation may be controlled largely by chemical factors, while oxic degradation may be more strongly controlled by biophysical and biochemical processes.

Measurement of sediment resuspension rates in Long Island Sound

Resuspension rates have been measured on Long Island Sound sediments (New York/Connecticut, USA) under an oscillating grid, using a flume, and in place, using high frequency acoustics, transmissometers, and sediment traps. Despite differences, the results compare favorably. The methods all provide an order-of-magnitude estimate of the resuspension rate and increases under storm conditions can be estimated.

Early diagenesis of chlorophyll-<I>a</I> in Long Island Sound sediments: A measure of carbon flux and particle reworking

Early diagenesis of chlorophyll-<I>a</I> in Long Island Sound sediments: A measure of carbon flux and particle reworking

Simulation of sulfur diagenesis in anoxic marine sediments using rickard kinetics for FeS and FeS 2 formation

Steady-state diagenetic profiles of reduced sulfur species (H 2S, FeS, FeS 2, and S°) have been modeled using Rickard's kinetic rate laws for goethite sulfidation and pyrite formation. The system of coupled, nonlinear differential equations that describe the diagenesis of sulfur is solved by numerical techniques in conjunction with a constrained, trial and error procedure for determining the correct gradient of H 2S at the sediment-water interface. The behavior of the model is sensitive to the values selected for the initial concentration of goethite and the particle sizes of goethite, FeS, and S°. Using trial and error we have been able to select values for these parameters that produce simulations similar to the profiles measured by the FOAM group in Long Island Sound sediments. Good fits between the model and the FOAM data, however, require a strong decrease with depth in the specific molar surface area of goethite, especially if available iron exceeds the limit to pyrite formation imposed by exhaustion of sulfate or organic matter. These model experiments suggest that Rickard's rate laws are an adequate base upon which to build a model for sulfur diagenesis. However, a truly comprehensive model for sulfur diagenesis will require incorporation of effects due to particle mixing, interaction of reduced sulfur with oxygen and variation of iron reactivity with depth. Calibration and validation of the present model or more complex models of the future will require data sets that include measurements of the molar surface areas of goethite, FeS, and S°. Without this information it is unlikely that a thorough and quantitative understanding of the vertical profiles of H 2S and FeS in marine sediments can be achieved.

Polycyclic aromatic hydrocarbons in surface sediments held in experimental mesocosms

Sediment was collected from three locations along a pollution gradient in Narragansett Bay and transplanted to controlled mesocosms. Total hydrocarbons and eleven individual polycyclic aromatic hydrocarbons (PAHs) were measured in these sediments over a period of 394 days. Total hydrocarbon concentrations increased in the “relatively uncontaminated”; (Rhode Island Sound) sediment that was held in the mesocosms, but did not change in the two other sediments. The concentrations of four PAHs: naphthalene, 2‐methyl naphthalene, 1‐methyl naphthalene and biphenyl, decreased in the “contaminated”; (Providence River) sediment during the experiment and the calculated half‐lives for these compounds were 287, 353, 321 and 333 days, respectively.

The role of sedimentary organic matter in bacterial sulfate reduction: The G model tested1

Laboratory study of the bacterial decomposition of Long Island Sound plankton in oxygenated seawater over a period of 2 years shows that the organic material undergoes decomposition via first‐order kinetics and can be divided into two decomposable fractions, of considerably different reactivity, and a nonmetabolizable fraction. This planktonic material, after undergoing varying degrees of oxic degradation, was added in the laboratory to anoxic sediment taken from a depth of 1 m at the NWC site of Long Island Sound and the rate of bacterial sulfate reduction in the sediment measured by the 35S radiotracer technique. The stimulated rate of sulfate reduction was in direct proportion to the amount of planktonic carbon added. This provides direct confirmation of the first‐order decomposition, or G model, for marine sediments and proves that the in situ rate of sulfate reduction is organic‐matter limited. Slower sulfate reduction rates resulted when oxically degraded plankton rather than fresh plankton was added, and the results confirm the presence of the same two fractions of organic matter deduced from the oxic degradation studies.Near‐surface Long Island Sound sediment, which already contains abundant readily decomposable organic matter, was also subjected to anoxic decomposition by bacterial sulfate reduction. The decrease in sulfate reduction rate with time parallels decreases in the amount of organic matter, and these results also indicate the presence of two fractions of organic carbon of distinctly different reactivity. From plots of the log of reduction rate vs. time two first‐order rate constants were obtained that agree well with those derived from the plankton addition experiment. Together, the two experiments confirm the use of a simple multi‐first‐order rate law for organic matter decomposition in marine sediments.

The mean residence time of plankton-derived carbon in a Long Island Sound sediment core: A correction

The mean residence time of plankton-derived carbon in a Long Island Sound sediment core: A correction

Trace metal fluxes to nearshore Long Island Sound sediments

Sediments are very important as trace metal ‘sinks’ in coastal areas. In this paper we present data on the concentrations and calculated fluxes of the trace metals, Fe, Mn, Cu, Pb, Zn, Cd and Ag at nearshore sites in Long Island Sound. In both areas a percentage of the metal accumulation can be ascribed to local human activities with the highest anthropogenic metal fluxes occurring closest to their source.