Cadmium and lead content of vegetable crops grown on land with a history of sewage sludge application

The bioavailability of cadmium to lettuce and cabbage in soils previously treated with sewage sludges

“…The correlation between total Cd in soil and lettuce is statistically significant. The slope of the linear regression equation for these two variables is 0.46, very similar to that reported by Chumbley and Unwin (1982), 0.41. This implies that the proportion of total soil Cd taken up by lettuce was very similar in these two independent studies.…”

“…tration in cabbage was 1.77/zg g-1 DW. This is higher than the mean observed in an ADAS review of sludged soils in the UK (Chumbley and Unwin, 1982) and national surveys in The Netherlands (Wiersma et al, 1986) and Spain (Zurera et al, 1987). Data for a set of polluted soils (Alloway, 1986) had a mean Cd concentration in excess of that found in this study.…”

Accumulation of cadmium in the edible parts of six vegetable species grown in Cd-contaminated soils

“…These calculations are based on the assumption that soil Cd has a bioavailability as high as that of the added Cd salt, which is generally not the case (see below) and should be regarded as the worst-case scenario in a risk assessment. The bioconcentration factor (BCF), defined as the ratio of metal concentration in the edible part to the total metal concentration in soil, was used to evaluate the transfer potential of a metal from soil to plant (Alloway et al, 1990;Chumbley and Unwin, 1982;Harrison and Chirgawi, 1989), which is a function of the properties of the metal itself, the soil properties and the genotype of the plant. The BCF values on the basis of fresh weight varied among vegetables, indicating the difference in the accumulation ability of Cd for six vegetables (Table 2).…”

Heavy metal content of vegetables irrigated with mixtures of wastewater and sewage sludge in Zimbabwe: Implications for human health

“…However the heavy metal content in plants can also be affected by other factors such as the application of fertilisers, sewage sludge or irrigation with wastewater (Devkota and Schmidt, 2000;Frost and Ketchum, 2000;Mangwayana, 1995). Heavy metal contamination of agricultural soils can pose long-term environmental problems and is not without health implications (Sauve et al, 1996;Ferguson, 1990;Chumbley, 1982). When the metals are derived from anthropogenic sources, this can strongly influence their speciation and hence bioavailability as is the case when metal contaminated sewage sludge is applied to agricultural land (Lester, 1987).…”