Soil, cadmium

Lamy, I., Bourgeois, S., and Bermond, A., Soil cadmium mobility as a consequence of sewage sludge disposal, J. Environ. Qual., 22, 731, 1993. 

Norvell, W. A., Wu, J., Hopkins, D. G., and Welch, R. M. (2000). Association of cadmium in durum wheat grain with soil chloride and chelate-extractable soil cadmium. Soil Sci. Soc. Am. J. 64, 2162-2168. 

Brams, E., Anthony, W., and Witherspoon, L. (1989). Biological monitoring of an agricultural food chain soil cadmium and lead in ruminant tissues. J. Environ. Qual. 18, 317. 

Shin, M., Barrington, S. F., Marshall, W. D., and Kim, J. W. (2005). Effect of surfactant alkyl chain length on soil cadmium desorption using surfactant/ligand systems. Chemosphere 58(6), 735-742. 

Jinzu Valley, Japan. One of the most infamous cases of contaminated land and health occurred in Japan and the effects were most prominent immediately after the Second World War. Around the end of the 19th century, soils in the Jinzu River basin, part of the Toyama prefecture, became contaminated with cadmium as a result of activities upstream at the Kamioka mines. The main activity at this mine was the mining and processing of zinc (cadmium is often associated with zinc ores) with the result that wastewater rich in heavy metals was discharged into the Jinzu River. Contaminants from this industry moved down-stream and caused contamination of soils in paddy fields as a result of abstraction of river water into fields in order to cultivate the local rice crop. Under favourable conditions, cadmium can be a fairly mobile heavy metal, particularly in soils with low pH, and increases in soil cadmium can often result in an increase in the uptake of cadmium by plants. This in turn results in an increase in dietary exposure and the consumption of contaminated agricultural crops can be a major pathway of human exposure. 

Increases in soil cadmium content result in an increase in the uptake of cadmium by plants. The uptake by plants from soil is greater at low soil pH. Processes that acidify soil (e.g. acid rain) may therefore increase the average cadmium concentrations in foodstuffs (WHO, 1992b). 

Biogeochemistry of soil cadmium and the impact on terrestrial food chain contamination... 

Chaney, R.L., Ryan, J.A., Li, Y.,-M. Brown, S.L., 1999. Soil cadmium as a threat to human health. In McLaughlin, M.J., Singh, B.R. (Eds.), Cadmium in Soils and Plants. Developments in Plant and Soil Sciences, vol. 85. Kluwer Academic Publishers, Dordrecht, Holland, pp. 219-256. 

This work is a valuable demonstration of the ease with which this element can enter plants as a first stage in food chains and, from the point of view of human or animal health, any enhancement of soil cadmium levels above the low background level naturally present in topsoil (around 0.13 ppm acetic acid-extractable cadmium) is highly undesirable. 

Lesser intakes of cadmium than those involved in Itai-Itai disease have since been associated with a number of other illnesses and the relationship between cadmium toxicity in mammals and the cadmium ingestion level appears to be complex. In the circumstances, any enhancement of soil cadmium levels in pastoral or agricultural soils must be regarded as highly undesirable. 

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