Zinc-65 accumulation

In echinoderms, zinc concentrations are usually higher in detrital feeders than in carnivores, higher in surface feeders than in sediment feeders, and higher in specimens collected inshore than those collected offshore in deeper waters (Eisler 1980). Sea cucumbers, Stichopus tremulus, accumulate radiozinc-65 from seawater by a factor of 1400 however, radiozinc accumulation data should be viewed with caution because addition of stable zinc can reduce zinc-65 accumulations in echinoderm viscera up to tenfold (Eisler 1981). Zinc inhibits the formation of the fertilization membrane in sea urchin eggs, possibly by interfering with cortical granule-derived proteases and proteins (Nakamura et al. 1989). 

Zinc Analysis. For EMI of zinc accumulation of Ps. 244, the ligand salicylaldehyde-2-quinolylhydrazone (SAQH) was used. The SAQH was prepared by refluxing sallcylaldehyde (Aldrich) with 2-hydrazlnoqulnollne (Kodak) as described by Sommer al. (12). In methodology analogous to the tin work described above, known quantities of biomass were exposed to 1.0-30.0 ppm aqueous solutions of ZnBtj. Cell samples were periodically withdrawn from the zinc solution in attempts to measure the kinetics of accumulation of the metal. For EMI analysis cells were suspended in 0.20 mL PIPES and were then treated with 0.10 mL of 3.0 x 10 M SAQH in EtOH. The cell samples were then rewashed and resuspended in 0.30 mL PIPES for EHI analysis (A, =366 nm, A, =498 nm). 

Cell suspensions which were exposed to 1.0 ppm zinc were combined, and to this matrix known amounts of Zn were added, to allow measurement of the amount of zinc accumulated by the cells via GFAA. In related work, cells treated with known concentrations of zinc solutions were systematically combined and thereby "diluted" with cells not exposed to zinc, to determine If GFAA and EMI analyses yield confirmatory results. 

Several attempts were made to monitor the uptake of Zn as a function of time. As a first attempt, the cells were exposed to 30 ppm Zn at room temperature. The rate of uptake of the Zn by the cells was much faster than was the case with Sn it was impossible to measure an increase in zinc content of the cells above that of the initial Zn -exposed sample either in florescence signal or GFAA signal by the methods described in this work. Reducing both the concentration of Zn in solution (10 ppm and 1 ppm) and the temperature (0°) did not slow down the uptake process enough to monitor an increase in accumulated Zn. By addition of known concentrations of Zn to the cells exposed to a 1.0 ppm Zn solution, it was found by GFAA that the amount of zinc accumulated... 

The maximum zinc concentration in earthworms collected from a contaminated site was 1600 mg/kg DW whole animal for uncontaminated sites it was 650 mg/kg (Beyer and Cromartie 1987). Whole-body zinc concentrations in earthworms (Dendrodrilus rubidus, Lumbricus rubellus) tended to reflect zinc concentrations in soil, although zinc accumulations in both species seem to be physiologically regulated when soil zinc values exceeded 1000 mg/kg DW (Morgan and Morgan 1988). 

No effect on growth, survival, or feed conversion. Zinc accumulated in tissue metallothioneins, especially in liver and kidney levels normal after 5 days on zinc-deficient diet (Oh et al. 1979). 

Devi, V.U. andY.P. Rao. 1989a. Zinc accumulation in fiddler crabs Uca annulipes Latreille and Uca triangularis (Milne Edwards). Ecotoxicol. Environ. Safety 18 129-140. 

Elliott, N.G., D. A. Ritz, and R. Swain. 1985. Interaction between copper and zinc accumulation in the barnacle Elminius modestus Darwin. Mar. Environ. Res. 17 13-17. 

Giesy, J.P., J.W. Bowling, and H.J. Kania. 1980. Cadmium and zinc accumulation and elimination by freshwater crayfish. Arch. Environ. Contam. Toxicol. 9 683-697. 

Handy, R.D. and F.B. Eddy. 1990. The influence of starvation on waterborne zinc accumulation by rainbow trout, Salmo gairdneri, at the onset of episodic exposure in neutral soft water. Water Res. 24 521-527. 

Lobel, P.B. and H.D. Marshall. 1988. A unique low molecular weight zinc-binding ligand in the kidney cytosol of the mussel Mytilus edulis, and its relationship to the inherent variability of zinc accumulation in this organism. Mar. Biol. 99 101-105. 

Mason, A.Z. 1988. The kinetics of zinc accumulation by the marine prosobranch gastropod Littorina littorea. Mar. Environ. Res. 24 135-139. 

Sauer, G.R. and N. Watabe. 1989. Ultrastructural and histochemical aspects of zinc accumulation by fish scales. Tissue Cell 21 935-943. 

Alsop, D. H. and Wood, C. M. (2000). Kinetic analysis of zinc accumulation in the gills of juvenile rainbow trout effects of zinc acclimatation and implications for biotic ligand modeling, Environ. Toxicol. Chem., 19, 1911-1918. 

Macnair, M. R., 2002, Within and between population genetic variation for zinc accumulation in Arabidopsis halleri. New Phytol. 155 59-66. 

Without zinc, silicon diffusion to the surface is slow under MCS conditions. Furthermore, when only tin is used as a promoter, no Cu is observed at the surface. Table 3 shows the elemental concentration under various conditions. Under MCS reaction conditions, when zinc was present silicon was not depleted from the subsurface, and when zinc was absent the subsurface was depleted in silicon. Zinc causes the rate of silicon diffusion and copper dispersion to increase. Zinc accumulates at grain boundaries and lowers the free energy of CU3SL Tin and zinc appear to work synergistically but tin does not enhance silicon diffusion on its own. Tin does appear to lower the surface energy of silicon/copper. 

The metals of most concern are the heavy metals, especially cadmium, lead, and mercury. Although it is a metalloid with characteristics of both metals and nonmetals, arsenic is commonly classified as a heavy metal for a discussion of its toxicity. Though not particularly toxic, zinc is abundant and may reach toxic levels in some cases. For example, zinc accumulates in sewage sludge and crop productivity has been lowered on land fertilized with sludge because of zinc accumulation. Copper may be toxic to plants. Aluminum, a natural constituent of soil, may be leached from soil by polluted acidic rainwater and reach levels that are toxic to plants. Other metals that may be of concern because of their toxicides include chromium, cobalt, iron, nickel, and vanadium. Radium, a radioactive alpha particle-emitting metal, can be very toxic at even very low levels in water or food. 

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