Food-chain transfer

HPLC has also been utilized in more complex food chain transfers. It has been known for some time that the toxins can be responsible for fish kills in the Bay of Fundy 18). The vectors for these fish kills are zooplankton that feed on toxic dinoflagellates. In two related studies (79 Sullivan, unpublished), HPLC was utilized to investigate the transport of toxins from dinoflagellates to zooplankton and then to fish. The HPLC method is ideally suited for this since only very small sample sizes (ca. 100,000 dinoflagellate cells) are required. 

Talmage, S.S. and B.T. Walton. 1993. Food chain transfer and potential renal toxicity of mercury to small mammals at a contaminated terrestrial field site. Ecotoxicology 2 243-256. 

Clements, W.H., J.T. Oris, and T.E. Wissing. 1994. Accumulation and food chain transfer of fluoranthene and benzo[a]pyrene in Chironomus riparius and Lepomis macrochirus. Arch. Environ. Contam. Toxicol. 26 261-266. 

Refining radionuclide food-chain transfer models... 

The US EPA characterizes As, Be, Sb, Cd, Cr, Cu, Pb, Hg, Ni, Se, Ag, Tl, and Zn as priority metals because of their potential hazardousness to human health. However, the environmental fate and effect of only a few metals (As, B, Cd, Cr, Cu, Mo, Ni, Pb, and Zn) have been studied extensively (Rechcigl 1995). For a given metal the potential to cause harm depends on the identifiable risk pathway, which is different for different metals. One pathway usually provides the highest probability of adverse affects to some receptor and is, therefore, the limiting pathway (Ryan Bryndzia 1997). The most toxic elements to humans are Hg, Pb, Cd, Ni, and Co. Some of the principal limiting pathways for various metals are the direct ingestion of Pb-contaminated soil by children plant phytotoxicity from Cu, Zn, Ni food-chain concentration and transfer of Cd and Hg to humans and food-chain transfer of Se and Mo to livestock (Ryan Bryndzia 1997). 

Swanson SM. 1985. Food chain transfer of U-series radionuclides in a northern Saskatchewan aquatic system. Health Phys 49 747-770. 

Watson AP, Etnier EL, McDowell-Boyer LM. 1984. Radium-226 in drinking water and terrestrial food chains Transfer parameters and normal exposure and dose. Nuclear Safety 25 815-829. 

Since Friedrich Wohler first synthesized urea in 1828, it is estimated that more than 1 million chemicals that were previously unknown in our environment have been synthesized. There are more than 80,000 chemicals manufactured and imported into the United States each year. People are exposed to most of these by air pollution, water pollution, foods and food chain transfers, soil contamination, household use of chemical products, the use of personal care and pharmaceutical products, and industrial contact. Exposure begins before birth in utero and continues throughout life. The different modes of exposure are dealt with separately in the following chapters. 

Vaughan BE. 1984. State of research Environmental pathways and food chain transfer. Environ Health Perspect., 353-371. 

Research on the behavior of Pu and other actinides in aquatic ecosystems of Oak Ridge National Laboratory involves field studies at White Oak Lake, a 10.5-ha impoundment formed by Mahattan Project operations. This final settling basin has received releases from the Laboratory and associated facilities since 1944. Some of the key questions addressed are (a) the partitioning of Pu between the suspended particulate and soluble fractions in the water column, (b) the partitioning of Pu between the bed sediments and overlying water column, (c) the uptake of Pu by biota from these fractions, and (d) food chain transfers and trophic effect on Pu concentrations in biota of the system. 

This book discusses the occurence and fate cf contaminants In soil, effects on organisms, bioaccumulation and food chain transfer, and ecotoxicological assessment procedures. 

Understanding the distribution of chemical forms of metals within certain water types, and their uptake into biota, is based on the electronic configuration of elements and the empirical classification of electron acceptors (metals) and donors (ligands) to hard and soff categories (Morgan and Stumm 1991, Raspor 1991). The relationship between the chemical properties of elements, and their uptake and accumulation - which has implications on detoxification and food chain transfer - will be considered. Classification of trace metals as either essential (Fe, Cu, Mn, Zn, Co) or non-essential (Hg, Cd, Ag, Pb) should be performed with caution, bearing in mind that the former can exert beneficial effects at low concentrations and harmful ones at higher levels. 

The trophic levels range from phytoplankton and macrophytes to zooplankton, invertebrates, fish and mammals. Food chain transfer is affected by the distribution of metals between different tissues of the prey, and by the marked degree to which this compartmentalization can vary at different trophic levels. 

Shea [41] developed a method that separated the toxins with micellar electrokinetic capillary chromatography, followed by detection with laser-induced fluorescence. This method was sufQ-ciently sensitive to follow food chain transfer of toxins from K. brevis cells in culture to planktivo-rous copepods and from the copepods to linlish [42], However, the requirements for derivatization of the sample and assay complexity again worked against common acceptance of this method. 

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