Cadmium inputs to the estuarine and marine environment as a probable carcinogen are derived from both natural and anthropogenic sources. The cadmium contents in the estuarine, coastal and marine waters varied between 4.4 and 5.0 g/L, and a maximum of 10.3 ^g Cd/L cadmium has been reported in the Changjiang estuary, China.
Both acute and chronic cadmium exposure can have toxic effects on aquatic organisms. Acute cadmium poisoning can cause death, and chronic (long-term, low level) exposure affects the reproduction, the mechanisms of which were the amount of cadmium accumulated and stored in the body increasing with exposure time and external concentrations. Once cadmium levels in their body (Critical Body Residues, CBRs) reach a particular level (threshold values), toxic effects occurs, initially sublethal but eventually lethal.
Waterborne and particle-bound (dietary) cadmium is bioavailable and toxic to M. monogolica. The concentrations inducing adverse effects showed that cadmium is present in aquatic environments at concentrations that are sufficient to provoke a biological response in the natural or indigenous biota.
In this topic, the concentration protecting 95% saltwater aquatic organisms calculated from the SMAVs is 81.44 g Cd/L. The important significance when using this benchmark and toxic thresholds is that protecting a large percentage of the species assemblage will preserve ecosystem structure and function. Furthermore, we illustrate the need to take the dietary pathway into account in regulatory assessments and to establish effective concentrations with particulate bound metals of WQC.
