Cadmium, contaminant concentration sediments

Although lead and cadmium sulfate are both soluble, a body of water contaminated with these toxicants in the presence of sulfate and biodegradable organic matter shows very low concentrations of dissolved lead and cadmium, although levels are relatively high in the sediments of the body of water. Explain. 

Chromium, Cu, Mn, Pb and Zn presented a similar distribution trend along the studied area, even though their concentrations are completely different (Figures 6.4-6.S ). This fact suggests that these metals have a similar behaviour in the evaluated environment, probably because they are controlled by similar processes and conditions. Cadmium contents in the analysed samples are in all cases below the LoDs of the method employed (<0.09 pg g dry weight). Iron showed a particular distribution pattern (Figure 6.8), which is probably related to its abundance (38). No evidence of trace metals in surface sediments of the Potter Cove was observed that could be attributed to contamination caused by scientific or logistic activities carried out in the Jubany Station. 

Researchers have found that bioavailability changes seasonally (Mendoza et al., 1996 Balras, 1999). In an assessment of various metals and their bioavailability, Mendoza et al. (1996) found that the bioavailabilty of cadmium and lead peaked in July, whereas cobalt peaked in early spring for organisms in their study area. Balras (1999) reported that fish tissue and sediment concentrations varied seasonally, with lead, cadmium and cobalt concentrations increasing in sediment samples in August-October samples. In general, it is believed that the seasonality of the bioavailable fractions is linked directly to increased temperature-influenced reaction kinetics and increased organism activity as temperature increases, whereas reduced temperatures typically reduce the bioavailability of a contaminant. 

Subsequent studies90 focused on the population structure of fish presenting tumors as well as the role of heavy metals. Overall neoplasm prevalence appears to be stable at about 22% of the population. No juvenile fish, out of 2000 + examined, exhibited tumors. Likewise, tumor prevalence did not appear to be seasonal or site specific within the Lake of the Arbuckles. Water, sediment and fish tissues were collected from the Lake of the Arbuckles, a reference lake outside the drainage, and were analyzed for total recoverable metals (cadmium, chromium, copper, nickel and lead) by graphite furnace atomic absorption. Chromium, copper and nickel were found in the water samples at concentrations of > 1 — 8.6 /xg/1. Low concentrations (>1-13.6 /xg/g wet weight) of all the metals were found in the sediment and liver tissues from both sites. Based on these concentrations, heavy metal contamination does not appear linked to neoplasm occurrence. 

The inorganic contamination of the sediment core was assessed by a determination of selected heavy metals. According to the screening programme of the ICPR (International Commission for the Protection of the Rhine), the elements cadmium, nickel, chromium, lead, copper and zinc were analysed. The vertical concentration profiles are shown in Fig. 4 including a corresponding time scale. 

Studies have found the following contaminants to be present, maximum concentrations in parentheses PCBs (10 mg/kg), mercury (3.4 mg/kg), lead (1,100 mg/kg), zinc (5,200 mg/kg), chromium (1,800mg/kg), copper (800 mg/kg), cadmium (18 mg/kg) and iron (5,500 mg/kg). In addition to the presence of these contaminants, fluctuating lake and harbor levels frequently expose large deposits of sediments and entrained debris which detracts from the aesthetics of the area (OMOE 1982). 

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