Marine environment trace metals

The application of neutron activation techniques to the measurement of trace metals in the marine environment has been reviewed by Robertson and Carpenter [815,816]. 

The determination of trace metals in estuarine, marine, and other waters is the subject of a booklet published by the Standing Committee of Analysts set up by the Department of the Environment UK [30]. 

Gardner MJ (1987) UK Analytical Quality Control for Trace Metals in the Coastal and Marine Environment, the Determination of Cadmium. Report PRS 1516-M, Water Res Centre, Medmenham, UK... 

Ecological Analysts, Inc. 1981. The Sources, Chemistry, Fate, and Effects of Chromium in Aquatic Environments. (Avail, from American Petroleum Institute, 2101 L St., N.W., Washington, D.C. 20037. 207 pp.) Eisler, R. 1981. Trace Metal Concentrations in Marine Organisms. Pergamon Press, NY. 687 pp. 

Bordin, G., J. McCourt, and A. Rodriguez. 1994. Trace metals in the marine bivalve Macoma balthica in the Westerschelde estuary, the Netherlands. Part 2 intracellular partitioning of copper, cadmium, zinc and iron — variations of the cytoplasmic metal concentrations in natural and in vitro contaminated clams. Sci. Total Environ. 151 113-124. 

At present, soil derived humic matter and fulvic acids extracted from freshwater are available commercially and are commonly used to test techniques for DOM detection and also used as model compounds for trace metal chelation studies. The results obtained using these model compounds are frequently extrapolated to the natural environment and measurements on "real" samples provide evidence that this DOM is a good model compound. In the past, some investigators also made available organic matter isolated from marine environments using C18 resins. While these compounds come from aquatic sources, this isolation technique is chemically selective and isolates only a small percentage of oceanic DOM. Reference materials are not currently available for these compounds, which inhibits study of the role they play in a variety of oceanographic processes. 

Table 28.8 Comparison of the Dissolved Concentrations of Trace Metals (nM) in the Ocean Outfall Seawater off the Tanshui Coast and in Other Heavily Polluted Marine Environments around the World. ...

Morrison, R.J., Gangaiya, P Naqasima, M.R. and Naidu, R. (1997) Trace metal studies in the great astrolabe lagoon, Fiji, a pristine marine environment. Marine Pollution Bulletin, 34(5), 353-56. 

Few trace element species can be analysed in natural samples directly. Ion selective electrodes (ISE) allow measurements of metal ion activity (Cu2+, Cd2+) however, their use in the marine environment is limited due to low sensitivity and interference by Cl-. 

The mixture of organic constituents in the marine environment is extremely complex. Their origin is partly terrigenuous many compounds are produced in the marine environment itself. The different sources and their relative importance for the complexation of trace metals in estuaries, coastal seas and open ocean are riverine input, runoff from the coastal zone, resuspension, import of water mases, atmospheric input and in situ biological production. 

Colloids. Colloids include particles with hydrophobic, hydrophilic and intermediate forms with a size range 1 - 400 nm. Both organic (including macromolecules) and inorganic (hydrolyzed silica and metal oxides) colloids occur in the marine environment (Sigleo and Helz, 1981). Their surfaces often contain suitable sites for interactions with trace metals (adsorption, complexation). In the marine environment all particles have a negative surface charge (Neihof and Loeb, 1972 Hunter and Liss, 1982). Increase of the electrolyte concentration decreases the stability of the colloidal particles. As a result the... 

Chester, R., Lin, F.J. and Murphy, K.J.T. (1989) A three stage sequential leaching scheme for the characterisation of the sources and environmental mobility of trace metals in the marine aerosol. Environ. Technol. Letts, 10, 887-900. 

The use of bioindicators and biomonitors for gathering environmental information is currently widespread, although some abuse of these terms is customary. The terms bioindicator and biomonitor are commonly but incorrectly taken to be synonymous a bioindicator provides qualitative information on the quality of the environment, whereas a biomonitor supplies quantitative data on environmental contamination.14 This section focuses on the latter, since the trace metal content of biota has been commonly used in biomonitoring programs of metal pollution in the marine environment and is considered to provide a time-integrated measure of metal bioavailability.1,15,16... 

Guo, L., Santschi, P.H., and Warnken, K.W. (2000a) Trace metal composition of colloidal organic matter in marine environments. Mar. Chem. 70, 257-275. 

Using techniques developed for the sampling and analyses of trace metals in marine precipitation by Tramantano, Scudlark, and Church (Environ. Sci. Technol.. in press), Church et al. (11) and Jickells et al. (12) have also reported on concentration measurements of the trace metals Cd, Cu, Fe, Mn, Ni, Pb, V, and Zn in wet deposition at Lewes, Delaware, and on Bermuda. The purpose of this facet of the WATOX research was to assess the sources of, the transport to, and the wet deposition of trace metals to the western Atlantic Ocean during nonsummer months. At this time of the year, trace metals are likely to be transported by a westerly air-mass flow from North America to the open Atlantic. Church and his colleagues report that the concentrations and wet deposition of trace... 

After a treatment of general aspects of metals in the marine environment, specific target organisms, mainly bivalves (clams, mussels, oysters) and tunicates are considered. The latter class of marine organisms, commonly referred to as sea squirts, allows us to trace the pathway of a specific element, vanadium, from outer to inner environment. 

Estuaries are the major pathway of materials from the rivers to the marine environment. In order to understand how dissolved and particulate organic matter v/ithin the estuary affect the speciation of cations within this environment, the ion exchange parameters as a function of ionic strength must be studied. In addition to the physical transfer of material between the dissolved and particulate forms, the salinity variations also affect the ion exchange abilities of these organic molecules. These two major processes can affect the organic material distribution and ability to bind metals, and hence the overall distribution of a given trace metal. 

Burton J. D. and Statham P. J. (1990) Trace metals in seawater. In Heavy Metals in the Marine Environment (eds. P. S. Rainbow and R. W. Furness). CRC Press, Boca Raton, FL. 

Seawater is the most extreme environment on Earth in terms of its paucity of essential trace elements. Marine microorganisms have thus evolved some of the most efficient uptake systems possible and take up trace metals at rates near the maximum allowed by physics and chemistry. One can calculate absolute hmits to the cellular uptake rates of metals by considering the simple case of uptake via transmembrane proteins (Hudson and Morel, 1990). 

Over the past several decades, the importance of trace elements in the marine environment has become apparent, with major regions of world s oceans now known to be affected by iron limitation, and with the first accurate measurements of incredibly scarce quantities of other essential metals. Yet, we understand little of how metal limitation manifests itself in the biochemistry of marine microorganisms or of the role of trace elements in the geochemistry of the oceans. But we now know enough to ask relevant questions at both the molecular and global scale, and are able to use novel experimental tools to help answer these questions. 

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