Investigation on Levels of Lead and Cadmium in Farmland Soil in Rikaze, Tibet

Objective To understand the levels of lead and cadmium in farmland soil in Rikaze, Tibet, and to provide the basis for objective evaluation of environmental safety. Methods Based on the requirements in the Monitoring Project for Environmental Hygiene in Rural Area of Tibet Autonomous Region in 2015, farmland soil samples from 5 counties of Rikaze, including Blanc, Nanmuling, Sajia, Lazi and Xietongmen, were collected and examined according to the Determination of the Soil Quality of Lead and Cadmium by Graphite Furnace Atomic Absorption Spectrophotometry (GB/T 17141-1997).Results Based on the results of 100 soil samples, the qualification rate of cadmium was 100% conformed to the first grade of the national standard for soil quality; the qualification rate of lead was 66% conformed to the first grade of the national standard and 34% for the second grade of the national standard. The levels of lead in Lazi, Sajia and Nanmulin county was significantly higher than those in other two counties; only 10% (2/20) of lead level in Nanmulin county was conformed to the first grade of the national standard. Conclusion Cadmium and lead levels in 40% (40/100) of farmland soil in Rikaze were conformed to the first grade of the national standard, but the lead level in other farmland soil were in the lower level of second grade of the national standard, which could not cause damage and pollution to plants and environment.