Cadmium In Parts Research Articles

Accumulation Characteristics of Copper and Cadmium in Greenhouse Vegetable Soils In Tongzhou District Of Beijing

The accumulation of heavy metals in greenhouse vegetable soil is one of the main reasons leading to the deterioration of soil quality and the contamination of agricultural products by heavy metals. A survey was conducted to determine the status of copper and cadmium accumulations in greenhouse vegetable soils in Tongzhou of Beijing. Based on the investigated results, the contamination degree of the two heavy metals in the greenhouse vegetable soils was assessed and the main influence factors caused the accumulation of copper and cadmium was analyzed. The results indicated that there was a distinct increase of copper and cadmium concentration in greenhouse vegetable soils. The concentrations of copper and cadmium in part of soil samples exceeded the environmental quality evaluation standard for farmland of greenhouse vegetables production of China. These over-standard soil samples were mainly collected from Lucheng town and Xiji town. The contents of copper and cadmium in greenhouse soil were increased significantly as the cultivated time of the soil added. The content of copper in greenhouse soil varied from 19.8mg/kg to 39.2mg/kg when the cultivation time of the greenhouse increased from 1 year to 5 years, nearly increased one times. The content of cadmium in vegetable soils of 20-year age greenhouse was 3.2 times of that in 1-year age greenhouse. Significant correlations were found between the content of copper and cadmium in soil, soil organic carbon content, CEC, and available phosphorus and potassium content in soils. Soil physical and chemical properties should be considerated integratedly to reduce the heavy metal contamination in greenhouse soils.

Implications for the human food chain of models of cadmium accumulation in sheep

Critical limits for cadmium in parts of the human food chain are considered to have too small margins of safety and some limits are regularly exceeded. There is concern about the exposure of some sections of the population to cadmium in the human food chain, in particular regarding offal, which is a major source of cadmium to some sectors. The kidney is the first organ of sheep to reach the limit of fitness for human consumption. A model (based on a meta-analysis) predicts that this would occur after a mean of just 130 days of feeding sheep the maximum permitted cadmium concentration in feed (in the European Union) in the organic form. Thus it is not surprising that sheep organs are found routinely to exceed cadmium limits. Since reduction of maximum cadmium levels in sheep feed or of the duration of their exposure are not economically viable measures of control, routine removal of liver and kidney from older sheep from the food chain is recommended as the best option to reduce human dietary cadmium intake from sheep origin.