To better understand the environmental fate of pesticides in Sri Lankan soils, we studied the sorption behavior of two commonly used pesticides (carbofuran and diuron) in 43 surface soils representing a range of soil physicochemical properties from dry and wet zones of Sri Lanka. For carbofuran, the K(d) (L/kg) values varied from 0.11 to 4.1 (mean, 0.83; median, 0.62) and K(oc) ranged from 7.3 to 120.6 (mean, 41.65; median, 36.1), whereas for diuron K(d) values varied from 0.5 to 75 (mean, 9.6; median, 5.15) and K(oc) ranged from 55.3 to 962 (mean, 407; median, 328). A comparison of sorption data on these tropical soils with published studies (mostly European and north American soils) showed that the ranges of sorption coefficients from Sri Lankan soils were within the wide range of K(oc) values reported in the literature. However, these values for both pesticides in soils from dry zones of Sri Lanka were consistently higher (up to two times) than those from the wet zone. The wide range of K(oc) values in Sri Lankan soils may be due to the possible difference in the nature of soil organic carbon, which needs to be further investigated.
The most common source of elevated As concentrations in the Australian environment are attributable to anthropogenic activities. Mining activities have contributed to the contamination of soil and water primarily in Western Australia and Victoria. However, other anthropogenic activities such as agriculture, forestry and industry have also contaminated soil and water at a localized scale. Currently there are over 1000 As contaminated sites previously used as cattle dips for eradicating cattle ticks. Although As contamination of the environment may be severe enough to limit plant growth there appears to be few other reports identifying the impacts of the contaminants on other organisms, such as fish, mammals and humans. In Australia the impacts of metal/metalloid contamination of the environment are often unnoticed or ignored. However, the impacts of elements such as As may pass unnoticed by the public or regulators due to the perception of the minimal impact a contaminant has on the environment. This paper presents an overview of As in the Australian environment including the sources of As contamination, soil, water and plant As content, and the pathways of exposure.
Despite an extensive cleanup program in the Port Pirie region, South Australia, the levels of lead (Pb) in blood of children have been found to exceed the "level of concern" (10 µg/dL). The ingestion of household dust is a major pathway for elevated blood lead by children in the community. Significant differences in levels of Pb in blood in children were observed in various localities around the smelter. In this study an in vitro test was assessed as one method for determining the bioavailability of Pb in household dust and for predicting levels of Pb in blood of children. The solubility of Pb in the dust decreased significantly as pH of the in vitro mixture increased. Correlation studies with average blood Pb levels of children in the corresponding area and in vitro measures of Pb bioavailability found that the best relationship was with total dust Pb (r 2 ) 0.92, **). A significant positive relationship was also found with Pb concentrations determined in the in vitro test at pH 3.0 (r 2 ) 0.82, **). This suggested that for these dust samples, which all had a similar environmental matrix, the use of the in vitro test was not a better indicator of blood Pb levels in children compared with a total Pb analysis.
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