摘要: As a major pollutant, cadmium can penetrate into organisms and create adverse effects (Thurberg et al., 1973; Bjerregaard and Vislie, 1985; Zyadah and Abdel-Baky, 2000). Although some studies have focused on its uptake and accumulation in aquatic organisms (Rainbow, 1995; Rainbow, 1997b), we are still far from having a complete understanding of the exact mechanisms involved in this process. In crustaceans, cadmium uptake from water occurs mainly through the gill epithelium (Jennings and Rainbow, 1979; Rainbow, 1997a). If the most obvious parameter controlling cadmium uptake is its own concentration in water, there is also a well documented role of salinity: the uptake, accumulation and toxicity of cadmium increase when the salinity of the water decreases (Wright, 1977b; Frank and Robertson, 1979; Hall and Anderson, 1995). This effect can be at least partially explained by cadmium speciation: in dilute water, the free metal ion, the bioavailable form, is the most common one due to a decrease of chloride ion concentration (Sunda et al., 1978; Gutknecht, 1983). In addition, it has been shown for a long time that accumulation and uptake of cadmium depends on the water calcium concentration. Usually, the more calcium is present in the external medium, the less cadmium accumulates (Wright, 1977a; Pärt et al., 1985). Ca2+ and Cd2+ have equal charges, similar ionic radii (Cd2+: 0.96 Å, Ca2+: 0.99 Å) and similar number of electrons in the outer shell. So, it has been suggested that cadmium is transported through membranes via, at least in part, the same uptake mechanisms as calcium such as Ca2+ channels, Na+/Ca2 …
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