Tianjin Sewage Irrigated Soil - Wheat System In A Heavy Metal Pollution Assessment And Analysis

With the rapid development of industry in our country, environmental pollution has been the most important problem that restricts economy development and affects human health and survival. The poisonous heavy metal is one of pollutants. The soil contaminated by heavy metals not only affects yield and quality of farm crops, pollutes the Earth's surface water and groundwater, but also hurts human beings by food chain. As a comprehensive industry city, Tianjin produces a huge amount of sewage every year. There is less water because people sets up dams, the climate becomes drier, industry and agriculture use more water. The dual threatening including shortage and pollution of water resources restricts the development of economy, agriculture and ecosystem.In order to find out completely the soil-wheat contaiminated by heavy metals in Tianjin sewage farm, we collect samples on the dry land and examinate contents of heavy metals (Cd, Cu, Pb, Zn, Cr and Ni) in soil-wheat system. Firstly, the anthor evaluates that soil irrigated by sewage that has been contaminated slightly, the main polluting factors are Cd and Zn, and then the anthor evaluates soil according to different regions, soil types and irrigating water. Secondly, the anthor analyzes content and enrichment ability of heavy metals in different part of wheat, evaluates wheat is contaiminated by Cd widespreadly, only few samples polluted by Zn.Finally the anthor put up correlative analysis about heavy metal contents in the soil-wheat system, as well as plant enrichment coefficient and some physico-chemical properties of soil, and establishes a prognostic model about heavy metal content among wheat spike, soil, soil types, PH, organic matter and salinity with the quantifying theory.The prognostic accuracy of primarily contaminative factors(Cd and Zn) is the best with compound correlative coefficient examining, the model can be founded.With improvement of living level, people need cleaner food. Therefore, studying enrichment and pollution of heavy metals in soil-wheat system provides scientific foundation not only for our understanding of enviromental quality but also for the decision- making by government department, which is meaningful to improve the quality of farm crops, guarantee food safety for resident, enhance people's living level and keeping agricultural sustainable development.