Ecological Risk Assessment For The Farmland Of Chongming Country, Shanghai

Ecological Risk Assessment (ERA) is a research field that rises and is developing gradually in recently 20 years. It is produced in order to adapt the transition of environmental management objectives and environmental management idea in the eighties of the 20th century. As for its definition, Ecological Risk Assessment is the assessment for the risk of the ecosystem or its components get. The present research examples mainly include the assessments for the risk of the water areas and soil ecosystem of heavy metal pollution, for the ecological risk biotechnology brings,, for the ecological risk of urbanization, and so on. But there are little examples of assessment for the ecological risk about the ecosystem of farmland and the depth of the assessmet is insufficiently. Chongming county is the only agriculture county of Shanghai, and agriculture has very important position in Chongming economy. Under such a background, the ecological risk assessment for its farmland ecosystem has very important academic and realistic meaning to Chongming country.At first this paper describes the characteristic of the ecosystem of farmland,and point out tha its risk sources include not only the natural disaster (flood, drought, plant disease and so on), but also the jamming (use chemical fertilizer, agricultural chemicals improperly, excessively cultivates and so on). Moreover, along with the economic activity intensity unceasing increasing, the human does more and more in jamming. The paper follows the step of the Ecological Risk Assessment, chooses the crops and soil fertility as the risk receptor. Based on the data investigated and study result had, the paper builds the assessment index system of the risk, and asseses the risk of the receptors.The main results of the paper as follows:1. Crops production risk assessment. According to the actual conditions of Chongming county, the paper divides the crops of Chongming county into the grain, cotton, rape, vegetables and melon, and chooses coefficient variation of per unit...