Showing papers on "Trace metal published in 1984"

A primer on trace metal-sediment chemistry

Abstract: In most aquatic systems, concentrations of trace metals in suspended sediment and the top few centimeters of bottom sediment are far greater than concentrations of trace metals dissolved in the water column. Consequently, the distribution, transport, and availability of these constituents can not be intelligently evaluated, nor can their environmental impact be determined or predicted solely through the sampling and analysis of dissolved phases. This Primer is designed to acquaint the reader with the basic principles that govern the concentration and distribution of trace metals associated with bottom and suspended sediments. The sampling and analysis of suspended and bottom sediments are very important for monitoring studies, not only because trace metal concentrations associated with them are orders of magnitude higher than in the dissolved phase, but also because of several other factors. Riverine transport of trace metals is dominated by sediment. In addition, bottom sediments serve as a source for suspended sediment and can provide a historical record of chemical conditions. This record will help establish area baseline metal levels against which existing conditions can be compared. Many physical and chemical factors affect a sediment's capacity to collect and concentrate trace metals. The physical factors include grain size, surface area, surface charge, cation exchange capacity, composition, and so forth. Increases in metal concentrations are strongly correlated with decreasing grain size and increasing surface area, surface charge, cation exchange capacity, and increasing concentrations of iron and manganese oxides, organic matter, and clay minerals. Chemical factors are equally important, especially for differentiating between samples having similar bulk chemistries and for inferring or predicting environmental availability. Chemical factors entail phase associations (with such sedimentary components as interstitial water, sulfides, carbonates, and organic matter) and ways in which the metals are entrained by the sediments (such as adsorption, complexation, and within mineral lattices). INTRODUCTION The basic goal of most chemically oriented water-quality studies is to describe or evaluate existing environmental conditions and to attempt to identify the source or sources of the constituents under investigation. An equally important goal is to attempt to predict or determine potential impacts. This heading could accommodate such subjects as bioavailability, amount of constituent transport, location of chemical sinks, ultimate fate, and potential toxic effects. Historically, the U.S. Geological Survey has attempted to assess trace metals in aquatic systems by analyzing water samples. This assessment has entailed determining concentrations of total and dissolved elements and compounds through the collection and analysis, respectively, of unfiltered and filtered water. Concentrations associated with suspended sediment (particulates, seston) are determined indirectly by the difference between total and dissolved concentrations. It is recognized that this approach casts doubt on the reliability of reported suspended-sediment chemical analyses. As a result, water quality tends to be evaluated on the kinds and concentration of various constituents found in solution (Feltz, 1980). However, in most aquatic systems, the concentration of trace metals in suspended sediment and the top few centimeters of bottom sediment is far greater than the concentration of trace metals dissolved in the water column. The strong association of numerous trace metals (for example, As, Cd, Hg, Pb, Zn) with seston and bottom sediments means that the distribution, transport, and availability of these constituents can not be intelligently evaluated solely through the sampling and analysis of the dissolved phase. Additionally, because bottom sediments can act as a reservoir for many trace metals, they must, for several reasons, be given serious consideration in the planning and design of any water-quality study. First, an undisturbed sediment sink contains a historical record of chemical conditions. If a sufficiently large and stable sink can be found and studied, it will allow the investigator to study changes over time and, possibly, to establish area baseline levels against which existing conditions can be compared and contrasted. Second, under changing environmental or physicochemical conditions (like pH, Eh, dissolved oxygen, bacterial action), sediment-bound trace metals can dissolve into the water column, possibly enter the food chain, and have a significant environmental impact. Third, several relatively inert or otherwise environmentally harmless inorganic constituents can degrade, or react with others, to form soluble and potentially toxic forms (for example, the conversion of elemental mercury to methyl-mercury). Finally, bottom sediments should be regarded as a major, if not the major, source of suspended sediment. Therefore, they must be investigated to determine transport potential. Under changing hydrologic conditions (such as a heavy storm or spring runoff), a localized pollution problem can suddenly become widespread and result in significant environmental impact. The foregoing discussion indicates that data on suspended and bottom sediments, as well as on the dissolved phase, are a requisite for the development of a comprehensive understanding of the impact of trace metals on water quality. Through the use of such additional data, it may be possible to begin to identify sources and sinks and the fate and potential effects of toxic or environmentally necessary metals. Similarly, sediment-chemical data are a requisite for transport modeling, for estimating geochemical cycles, and for inferring the availability of various trace metals in an ecological system.

Trace metal content of the forest floor in the green mountains of Vermont: Spatial and temporal patterns

Abstract: The organic horizons of forest soils in eleven stands along an elevational gradient on Camels Hump Mountain, Vermont, were analyzed for Pb, Cu, Zn, Ni, Cd, organic matter and organic C. Lead concentration and amount increased with elevation. Vertical profiles of forest floor in the boreal forest showed that highest concentrations for most metals occurred in the upper F horizon. Comparison with 1966 and 1977 samples from the same stands showed that concentrations of Pb, Cu, and Zn and percent organic matter increased by as much as 148% in the intervening 14 yr. Estimates of 1966 amounts of Pb, Cu, and Zn indicated that increases in trace metal amounts over the 14 yr period are consistent with annual deposition rates reported in the literature.

Trace metals in Bermuda rainwater

Abstract: The concentrations of Cd, Cu, Fe, Mn, Ni, Pb, and Zn have been measured in Bermuda rainwater. Factor analysis indicates that Fe, Mn, and Pb have similar origins to acidic components derived from North America. The other metals all behave similarly but differently to the acids. Sea salt, even after allowances for fractionation, apparently contributes minor amounts of Cu, Pb, and Zn and uncertain amounts of Fe, Mn, and Cd to Atlantic Ocean precipitation. Wash-out ratios, calculated from this data along with earlier measurements of atmospheric trace metal concentrations on Bermuda, are of the same order as those reported from other remote ocean areas. The wet depositional fluxes of Cu, Ni, Pb, and Zn to the western Atlantic Ocean are significant compared to measured oceanic flux rates. However, the wet depositional fluxes of Fe and Mn to this area are relatively small, suggesting additional inputs, while an excess wet depositional flux of Cd suggests large-scale atmospheric recycling of this element.

Bioaccumulation of heavy metals by bivalves from Lim Fjord (North Adriatic Sea)

Abstract: Trace metal concentrations (Zn, Cd, Pb and Cu) were studied in two different bivalve species of the same age, the mussel Mytilus galloprovincialis, Lmk., and the oyster Ostrea edulis, Linnaeus, which had been grown in the water of Lim Fjord, North West Yugoslavia (Peninsula Istria), i.e. under the same physicochemical conditions. The study offers a realistic view on the metal accumulation ability of oysters and mussels. The distribution of trace metals over the different organs and the edible parts of the mussels and oysters, collected in June 1979, was determined and is discussed in detail. The results are supported by the determination of the trace metal levels in the dissolved state and in the suspended material in the ambient sea water of the bivalves. Concentration factors for zinc, cadmium, lead and copper in the mussels of: 95 000, 9 100, 1 500 and 4 000; and in the oysters of: 95 500, 30 400, 3 400 and 64 500 were found, respectively. The values were evaluated comparing the metal concentration in the bivalve soft part and the dissolved trace metal levels in the adjacent water.

Particle flux and trace metal residence time in natural waters1,1

Abstract: A simple inverse relationship between trace metal residence time and particle flux through the water column is tested on the trace metals Zn/sup 2 +/ in fresh water and Th(IV) in ocean water systems with available data on the vertical flux and concentration of particulate matter and Zn/sup 2 +/ in lakes or on the disequilibrium of U/Th nuclides in the ocean. Natural or model aquatic ecosystems with different chemical compositions and particle fluxes confirm the concept that the particle flux through the water column is the major factor regulating trace metal concentrations in natural waters.

Carbonate and bicarbonate trace metal complexes: Critical reevaluation of stability constants

Abstract: The anions HCO3- and CO32- could play a major complexing role for trace metals in CO2 rich thermomineral water. The aim of this paper is to provide a complete thermochemical data set concerning the aqueous complexes of some divalent metal complexes (Fe, Mn, Ni, Co, Cu, Pb, Zn, Cd) with the ligands HCO3- and CO32-. When not previously determined experimentally, stability constants and enthalpies of formation of the complexes were estimated at 25°C from empirical correlations or theoretical approaches. The distribution of the trace metal species in typical water samples is given, indicating that the importance of complexes with bicarbonate cannot be neglected in that type of water.

Sediments and the Transport of Metals

Abstract: Sediments are important carriers for trace metals in the hydrological cycle, an aspect which will be discussed in chapters dealing with individual parts of the hydro-logical cycle. However, sediment research has certain aspects of its own, which warrants a separate discussion. Therefore, we will discuss those aspects of metals and sediments which are common to all parts of the hydrological cycle.

The distribution and geochemistry of some trace metals in the Bermuda coastal environment

Abstract: Results of the analyses of the water column and sediments of the Bermuda Platform for Cd, Cu, Fe, Mn, Ni, Pb and Zn are presented. The major process controlling the water column concentrations is physical mixing of open ocean waters with inshore waters, which are polluted by a wide range of diffuse inputs. Sedimentation within the inshore waters plays a lesser, but significant, role as do fluxes from the sediments of Fe and Mn and possibly phytoplankton uptake of Zn. Concentrations within the sediments are controlled by the formation of trace metal enriched clay/organic particles in the inshore areas and their subsequent redistribution by sediment resuspension, except for Fe and Mn which are largely associated with clay lattices.

Transport of Trace Metals in Marine Food Chains

Abstract: For most trace metals the first trophic level (seawater — phytoplankton) shows the highest concentration increase. In the next trophic level (zooplankton) only Cd, Cu, and Zn concentrations increase. Plankton feeding fishes have higher Cu and Zn levels than fishes preying on invertebrates and fish. The Cu, Zn, and probably Cd concentrations are higher in shrimps feeding on invertebrates than in fishes feeding on shrimps. For these three trace metals the concentrations at first increase along the food chain reaching a maximum with crustaceans, and then decrease in fishes. The concentration of mercury increases with size (i.e., age) of the organisms. Its increase along the food chain does not become evident in short-lived organisms. This increase with size and the fact that long-lived organisms are at the top of the food chain are responsible for the mercury increase along the food chain. Mercury is also the only trace metal which poses a risk to heavy consumers of seafood, especially in areas with high natural mercury levels such as the Mediterranean. The significance of the elevated mercury level in hair and blood of these persons also needs to be evaluated in light of the antagonistic action of the selenium present in seafood. The reevaluation of the lead levels in marine foods shows that only very little Pb enters man through the marine food chain and that, therefore, Pb is not a marine pollutant of concern. Very high As concentrations have been observed, especially in benthic organisms. Although most of the As is in a very low toxic or nontoxic organic form in organisms with high total levels, still considerable amounts may be present in the toxic inorganic form. At present not enough data are available to assess possible risk.

Trace metal composition of and accumulation rates of sediments in the Upper Gulf of Thailand

Abstract: Sediment cores and grab samples were collected in the Upper Gulf of Thailand to determine sedimentation rates and to determine if metal concentrations reflect anthropogenic inputs. Accumulation rates of sediments in the Upper Gulf measured using the 210Pb method, appear to vary from ca. 4 to 11 mm yr−1. Sediment budgets suggest that little of the sediment delivered to the Upper Gulf by the major rivers is ultimately transported to the Lower Gulf. Metal concentrations in Upper Gulf sediments appear to be dominantly controlled by natural inputs.

Statistical models for the accumulation of PAH, chlorinated hydrocarbons and trace metals in epiphytic Hypnum cupressiforme

Abstract: Concentrations of PAH (1.12-benzoperylene, 3.4-benzopyrene, fluoranthene), chlorinated hydrocarbons (α-BHC, lindane, PCB) and trace metals (Zn, Pb, Cu) in bulk precipitation, as well as PAH and trace metal concentrations in atmospheric dust samples from 14 sites in Bavaria, F.R.G. are presented for two vegetation periods (1979 and 1980).

Trace metal changes associated with age of marine vertebrates.

Abstract: Concentrations of selected trace metals in feral populations of marine and coastal elasmobranchs, teleosts, birds, and pinniped mammals are clearly related to age. Regardless of species or tissues, all data for individual metals, except Mn, showed the following trends: increases in Cd, Pb, Hg, and Se with increasing age of the organism; and decreases in Cr, Cu, Fe, Ni, and Zn. For Mn, mammals showed an increase with age whereas birds and fish exhibited decreases. The biological implications of these observations are imperfectly understood at this time. Factors that may account, in part, for these trends include differential uptake at various life stages, reproductive cycle, diet, general health, bioavailability of different chemical species, metal-metal interactions, metallothioneins, critical body parts, and anthropogenic influences.

Complexation Capacity and Conditional Stability Constants for Copper of Sea- and Estuarine Waters, Sediment Extracts and Colloids

Abstract: Trace metals in the environment occur in a variety of forms in solution, in colloids and particulates. Speciation studies try to distinguish between different dissolved forms (valence state, ionic, (in)organic complexed). Speciation has become important in studies concerning transport processes and the fate of trace elements. The toxic effects of trace elements are very much related to their form in the environment (see eg. Langston & Bryan, this volume).

The Relationships Between Metal Speciation in the Environment and Bioaccumulation in Aquatic Organisms

Abstract: Recent advances in methodology have resulted in a much better understanding of the speciation of metals in natural waters. However, despite the realization that the speciation of elements is important in terms of bioavailability and toxicity, progress in understanding the relationships between metal levels in organisms and those in the environment has been slow. Furthermore, emphasis has generally been placed on the bioaccumulation and toxicity of dissolved metals, although in many organisms sediment particles or food may be the most important sources. The ability of aquatic organisms to accumulate metals from a number of different sources complicates organismenvironment relationships. In addition, these relationships are markedly influenced by the differing capacities of organisms to metabolise metals. Thus, variations between the toxicities of metals to different species depend not only on the bioavailability of the metal in the environment but also on the physiological state of the organism. It is also important to evaluate speciation of metals within the framework of their roles as essential (for example Fe, Cu, Mn, Zn, Co) or non-essential elements (Hg, Cd, Ag) bearing in mind that some metals can exert beneficial effects at low concentrations and harmful ones at higher levels.

Trace-metal geochemistry of sediments from Baffin Bay

Abstract: The major- (Si, Al, Ti, Fe, Mn, Ca, Mg) and trace-metal (Zn, Cu, Pb, Co, Ni, Cr, V, Li, Cd, Hg) compositions of surficial sediments from Baffin Bay and the sounds (Lancaster, Jones, Smith) leading into the Arctic Ocean have been determined. The sediment composition varies regionally and in response to textural variations and the heavy-metal concentrations are at or near natural levels in relation to their source rocks and other uncontaminated shelf and oceanic sediments.Chemical partition indicates that most of the heavy-metal concentrations (80–99%) except for Cd (27–71%) are derived from various sulphide, oxide, and silicate minerals. The host minerals are predominantly fine grained and have accumulated at the same rate as other detrital clastic material of comparable grain size. As a result, the highest trace-metal concentrations occur in the fine-grained sediments occupying the deepest parts of the sounds and Baffin Bay. Although most of the metals have reached their depositional site by water transpo...

Dissolved and particulate trace metals in coastal waters of the Gulf and Western Arabian Sea

Abstract: Concentrations of chemical species of selected heavy metals (Cu, Zn, Cd, Hg and Pb) were determined in surface waters from a series of coastal sites in Bahrain, United Arab Emirates (UAE) and the Sultanate of Oman. Analyses were carried out on bulk sea water samples as well as on suspended particulates by anodic stripping voltammetry. Heavy metal concentrations were relatively low with the exception of some “hot spots” which occurred in the vicinity of industrial and port activities. Average copper levels along the coast of UAE were generally higher than those measured in sea water from either Bahrain of Oman. Waters from the more populated and industrialised northwest coast of Oman were found to contain approximately 3 to 4-fold higher Cd and Zn (pH 4–4.5) concentrations than those from the southern coast, an undeveloped region adjacent to the more open waters of the Arabian Sea. Possible reasons for the observed regional variations in trace metal concentrations in Oman are discussed in terms of natural and anthropogenic input sources. Average concentrations in the Gulf (inside the Strait of Hormuz) were 510 ng 1 −1 (Cu), 340 ng 1 −1 (Zn), 20 ng 1 −1 (Cd), 16 ng 1 −1 (Hg) and 76 ng 1 −1 (Pb); in the western Arabian Sea along the coast of Oman concentrations averaged 290 ng 1 −1 (Cu), 180 ng 1 −1 (Zn), 37 ng 1 −1 (Cd), 11 ng 1 −1 (Hg) and 80 ng 1 −1 (Pb). Ranges of concentrations for these metals in Gulf and western Arabian Sea waters approach those which have been reported for open surface waters of the Atlantic, Pacific, Indian Oceans and the Mediterranean Sea indicating that, in general, the coastal waters of this region are not impacted by metal pollution and that the existing natural levels can be used as a point of reference for future pollutant studies.

Trace metal concentrations in fish from the South Esk River, Northeastern Tasmania, Australia.

Abstract: A comprehensive ecological study of the South Esk River (Norris et al., 1980,1981,1982) has provided detailed information on basic water characteristics, concentrations of metals and the relationship of these factors to the distribution and abundance of benthic macroinvertebrates. The numbers of individuals and the variety of species of macroinvertebrates were both much reduced downstream of the source of trace metals from mines entering the South Esk River clearly indicating the low levels of metal contamination. As an adjunct to the study of the South Esk River reported by Norris et al. (1980,1981,1982), an investigation was made of the concentrations of zinc, cadmium and copper in South Esk River fish. The purpose of the work reported here was to assess the value of determining metal concentrations in freshwater fish to indicate metal pollution. Such a practice has been reported as being successful for metals such as mercury and cadmium (Bayly and Lake 1979, Forstner and Wittman 1981). A further aim was to provide information on metal concentrations in fish as few data have been published for Australian rivers (Bayly and Lake 1979).