Distribution Of Lead And Its Bioaccessibility In Soil Aroundbattery Plant

In recent years, there is a widespread concern about lead (Pb) pollution in the air and soil environment resulting from the rapid development of battery industries. Human exposure to Pb occurs through inhalation, ingestion, dermal contact, and incidental oral ingestion. There into, incidental oral ingestion of soil was more important for children through outdoor hand-to-mouth activities. In view of this,84soil samples were collected around six battery plant sites of easten and central China. An in vitro digestion test was used to assess the bioaccessibility of Pb in soil, followed by preliminary health risk assessment of Pb bioaccessibility. The relationship of between Pb bioaccessibility and the soil properties was analysised.The results showed that soil Pb pollution in six battery plants varyied degrees, and the total lead in the soil increased with the running time of the battery factories. The content of soil Pb inside plants were significantly higher than that of outside plants. The spatial distribution of Pb content in soil outside battery plants were consistent with the dominant wind direction, wind speed and settlement, and Pb content in soil decreased quickly in the distance of0-50m to battery plants.Pb bioaccessibility in gastric phase range from4.2%to66.9%, were significantly higher than those in small intsetine phase(0.25%～9.29%), due to the strongly acidic environment of the stomach. Pb bioaccessibility of soils inside plants were higher than those of outside, and Pb bioaccessibility outside battery plants decreased quickly as total Pb within0-50m distance. However, a great deal of inconsistency existed between Pb bioaccessibility and total Pb content, which demonstrated that the Pb bioaccessibility were related to other than total Pb of soils outside battery plants.Bioaccessible Pb were significant positively correlated with total Pb in the soils, and also correlated with Fe, Mn, clay, and silt content. The higher soil organic matter (SOM) content and sand content, and lower clay and silt content, the larger its Pb bioaccessibility. But the presence of Fe and Mn could help reduce the soil Pb bioaccessibility. Pb emission from the battery plants into soil present their occurrence forms according to the soil physico-chemical properties. Pb bioaccessibility of soils inside battery plants was higher than that of outside, due to its large deposition limited area of soils inside of battery plants; while Pb bioaccessibility in soils outside battery plants was lower and irregular distributed due to its small deposition the large area of soils.Health risk assessment of Pb was conducted comparing to acceptable daily intake from World Health Organization(WHO). The calculated absolute health risk coefficient (Ka) and the relative risk coefficients (Kr) of soil Pb inside battery plants which have more5years running time, were higher than the tolerant lead intake level for children, and exceed the children health risk warning lineset by WHO, but not exceed the adult health risk warning line. The health risk of lead in soils outside battery plants within0-50m distance was higher for children.