农业土地利用系统的环境风险分析与评价方法研究:以湖南省桃江县为例

Methods for Environmental Risk Analysis and Assessment of Agro-Land Use Systems

通过对农业土地利用系统的过程和输入-输出特征解析,构建了农业土地利用系统概念模型,从系统输入、土地利用过程和输出3个方面分析了农业土地利用过程中的环境风险源,探讨了针对农业土地利用系统的环境风险识别与评价方法。在此基础上,以乡镇为评价单元,逐一识别相应的环境风险因子,评价各类环境风险水平,并依据每个评价单元需要关注的风险种数评价其综合风险水平。以湖南省桃江县为例,对该县农业土地利用系统中的污水灌溉、肥源投入、农药投入、地膜施用和秸秆焚烧等人为因素带来的环境风险进行评价,结果表明,由于该县南部地区的工厂和采矿活动密集以及土地利用集约度高,农业土地利用系统的综合环境风险程度呈南高北低的趋势。

A conceptual model of agricultural land use systems was established through analysis of the process and characteristics of input and output of the systems.With the aid of the model,analysis was done of environmental risk sources in the processes of agricultural land use from the aspects of input,land use processes and output of the systems.Methods for identification and assessment of environmental risks of the systems were explored.On such a basis,relevant environmental risk factors at a town or township level were identified one by one and assessed.In light of the number of risks each evaluation unit is concerned about,comprehensive risk level of each unit is assessed.Taojiang County of Hunan Province was cited for case study.Environmental risks of sewage irrigation,fertilizers and pesticides application,plastic mulching,straw burning and some other human activities were assessed.Results show that the comprehensive environment risk level in the southern part of the county is higher,because of intensive industrial and mining activities and land use,and the county as a whole displayed a declining trend from south to north in comprehensive environment risk level.