Fuzzy Comprehensive Evaluation Of Environmental Quality Of Major Food Crops Producing Areas In Northern Jiangsu

Food security has always been a major strategic issue relating to the national economic development, social stability and national self-reliance. Conscientiously implementing the "national food security long-term planning framework (2008-2020)", and to protect and improve food quality from the source by strengthening of environment monitoring and evaluation of food crops producing area, have significance in improving agro-ecological environment in China’s major food-producing areas, ensuring food security, expanding agricultural products trade and promoting sustainable agricultural development.This paper evaluates the of special and inter-annual variation in environmental quality of soil, irrigation water quality, food quality by applying fuzzy comprehensive evaluation model, based on GPS positioning monitoring and investigation of the evrionmental conditions of soil and irrigation water, as well as collection and analysis of producing environment and food product samples, main food crops producing area in Northern Jiangsu as the research object. And the correlative analysis of heavy metals metal evaluation factors reveals the intrinsic correlation between the heavy metal content in environment of producing areas and food. The major findings are as follows:(1) The soil environmental quality of these producing areas is generally good, with little difference in spacial and inter-annual variation. In spatial changes, the integrated fuzzy value shows that the soil environmental quality of 25 counties (districts) are of grade I as cleanliness, while Guanyun County of Lianyungang City as the only one belongs to grade II. There are differences within the same level of membership of different sizes, with the order of Yancheng> Suqian> Huai’an> Xuzhou> Lianyungang, in accordance with the principle of maximum membership degree. In inter-annual variation, the order is year 2008 > year 2006> year 2007 in Xuzhou, year 2008> year 2007> year 2006 in Huai’an, year 2008> year 2007> year 2006 in Suqian, and year 2007> year 2006> year 2008 in Lianyungang, while nearly no changes in membership degree of Yancheng from year 2006 to year 2008. And the evaluation results also shows that within all these heavy metals evaluated, lead (Pb), cadmium (Cd), arsenic (As) has greater impacts on soil environment quality, especially lead (Pb), and mercury (Hg) and chromium (Cr) has smaller contribution to the evaluation results.(2) The irrigation water environmental quality of these producing areas is generally good, with much difference in spacial and inter-annual variation. In spatial changes, the integrated fuzzy value shows that the water environmental quality of all 26 counties (districts) in Northern Jiangsu are of grade I as cleanliness, but 22 counties (districts) degree lower than 0.9, with the order of Xuzhou> Lianyungang> Suqian> Yancheng> Huai’an according to the principle of maximum membership degree. In inter-annual variation, the order is year 2008> year 2007> year 2006 in Xuzhou, year 2006> year 2008 > year 2007 in Huai’an, year 2008> year 2006> year 2007 in Suqian, and year 2006> year 2008> year 2007 in Lianyungang, while nearly no changes in membership degree of Yancheng from year 2006 to year 2008. And the evaluation results also shows that within all these heavy metals evaluated, lead (Pb), arsenic (As) has greater impacts on water environment quality, while mercury (Hg) chromium (Cr) and cadmium (Cd) has smaller contribution to the evaluation results.(3) The qualities of food in these producing areas are generally good, with little difference in spacial variation and various differences in inter-annual variation. In spatial changes, the integrated fuzzy value shows that the grain food qualities of all 26 counties (districts) in Northern Jiangsu are of grade Ⅰ, all with membership degree higher than 0.86, with the order of Lianyungang> Suqian> Xuzhou> Yancheng> Huai’an according to the principle of maximum membership degree. In inter-annual variation, the membership degrees of Xuzhou, Huai’an, Suqian and Lianyungang from year 2006 to year 2008 are the same, year 2008> year 2007> year 2006, while year 2008> year 2006> year 2007 in Yancheng. The evaluation results also shows that heavy metals have little impact on food quality, and within all these heavy metals evaluated, lead (Pb), mercury (Hg) and arsenic (As) contained in grains are over the limit values in a few couties (districts), and cadmium (Cd) contained in grains are bellow the limit values in all couties (districts).(4) The fuzzy comprehensive evaluation model, taking full consideration of a variety of factors influcing the environmental systems quality and security of food producing areas, combined with qualitative and quantitative analysis, can effectively minimize the influence of evaluation results caused by evaluation standards choosing and monitoring error. The model uses correlation coefficient method empowerment, not only taking into account the relationship between the evaluation indexes, but also considering the evaluation indexes contributing to the pollution in producing areas, avoiding the impact of human subjective experience, accordance with the objective evaluation index between the importance of linkages and mutual. Combined using with MapInfo enables the model to give the evaluation results stratified visible and more intuitive, which are good support to the evaluation work.