Abstract:
To reduce the influences of soil heavy metal pollution on the quality and safety of tobacco leaves, the contents and accumulation conditions of five heavy metals(arsenic, lead, cadmium, chromium and copper) were analyzed. On the basis of environmental quality standard for Grade Ⅱ soil as described in GB 15618-1995, a single-factor pollution index, Nemerow comprehensive pollution index and potential ecological risk index were used to assess soil environmental quality in Hezhou. The results showed that the contents of As, Pb, Cr and Cu in Hezhou tobacco-growing soils were lower than those specified by the environmental quality standard for Grade Ⅱ soil. However, the Cd content exceeded the standard. The accumulation index of As, Pb and Cr were 0.43, 0.51 and 0.62, respectively, suggesting no accumulation. The accumulation index of Cu and Cd were 1.12 and 1.06, respectively, indicating a slight accumulation due to human activities. The Nemerow comprehensive pollution index of 91.1% of the soil samples were at GradeⅠ(clean)or GradeⅡ(practically clean) in Hezhou tobacco-growing areas and the multi-metal potential ecological risk indexes(
RI) of all the samples were less than 150, which indicated that the soil environmental quality in Hezhou tobacco-growing areas was at the level of"clean"or"practically clean"and low potential ecological risk. Single-factor pollution index of Cd from five sampling points were higher than 1.0, and potential ecological risk of Cd from two sampling points were at the strong level. Therefore, tobacco-growing areas should be selected in Hezhou to avoid Cd pollution areas.