山东省化肥使用时空分异及潜在环境风险评价

为了更为系统地认识农田化肥过量使用对生态环境的潜在威胁机理,加强化肥使用风险管控,该研究以山东省为实证对象,对其化肥使用的时空分异和环境风险进行评价。通过综合考虑化肥使用的强度、效率、环境安全阈值、环境效应权数及作物复种指数等因素,构建了化肥使用面源污染环境风险评价指数模型。结果表明:山东省的化肥使用明显过量。634.1 kg/hm~2的化肥使用强度是中国生态县建设标准250kg/hm~2的2.5倍。化肥使用强度最高的枣庄市878.7 kg/hm~2,是最低的滨州市473.7 kg/hm~2的1.85倍,区域差异不太悬殊。2012年山东省化肥污染的环境风险指数是0.75,总体处于中度风险程度。但是,烟台市处于严重风险,潍坊、济宁和枣庄处于重度风险。同时山东省存在磷肥污染严重环境风险,氮月巴污染重度环境风险,钾肥污染中度环境风险。山东省过量的化肥使用不仅存在较为严重的环境污染风险,并对生态环境产生了不利影响。国家和地方应该尽快实行地区化肥使用总量控制和分区管控指导,确保农业健康可持续发展。

Spatio-temporal differentiation and environmental risk assessment of fertilization in Shandong Province, China

Abstract: Studies on spatio-temporal differentiation and environmental risk of fertilization in Shandong Province were conducted to reveal potential threats of fertilizers to the ecological environment, and strengthen environmental risk awareness and management. Such factors as fertilization intensity, fertilization efficiency, fertilization environmental safety threshold, weight of fertilizer effect on environment, multiple cropping index were introduced into the Fertilization Environmental Risk Index Model (FERIM). The model set up the risk index values between 0 and 1 to assess the fertilization environmental risk of Shandong. Based on the proportion of 1:0.5:0.5 for N:P:K in Shandong and the standard of 250 kg/hm2 for the construction of ecological counties sponsored by Chinese government, the numbers of 125, 62.5, and 62.5 kg/hm2 was considered as environmental safety thresholds for N, P, and K, respectively. Analytic hierarchy process (AHP) was used to determine the weights of N, P, and K. Results were shown as follows. 1) The rate of farmland fertilizer in Shandong was 634.1 kg/hm2, which was 2.5 times as many as the standard of 250 kg/hm2 with the regional difference from the maximum of 878.7 kg/hm2 to the minimum of 473.7 kg/hm2. The proportion of 1:0.5:0.5 for N:P:K was reasonable for crops in Shandong with little regional differentiations. 2) Environmental risk index of Shandong was 0.75 at medium risk degree, with sub-regions of Yantai at serious risk degree at 0.81 risk index and Weifang, Jining and Zaozhuang at severe risk degree in the range of risk index from 0.76 to 0.78. As for nitrogen fertilizer environmental risk, Yantai and Zaozhuang were at severe degree in the range of risk index from 0.78 to 0.80, except for the rest 15 regions at medium degree in the range of risk index from 0.70 to 0.75, while the environmental risk situation for phosphorus use was serious, with Yantai at extreme risk in 0.86 risk index, seven regions of Qingdao, Rizhao, Weifang, Dongying, Zaozhuang, Jining and Liaocheng at serious degree in the range of risk index from 0.81 to 0.84, the rest 9 regions at severe degree in the range of risk index from 0.76 to 0.80. But the environmental risk situation for potash use is relatively light, with southeast part of Shandong where there were seven regions at medium degree in the range of risk index from 0.68 to 0.75 and northwest part where there were ten regions at light degree in the range of risk index from 0.56 to 0.65. 3) Overload fertilizers had resulted in serious environmental problems in Shandong. It made the concentration of NO3-N increasing in the groundwater and acidification of soil in the pH value of less than 5.5 for 63% orchard land in some regions, which was not suitable for apple tree growth. Therefore, governments at all levels in Shandong should regulate the fertilizer use with laws or rules, control the total amount of fertilizers' use and guideline farmers' fertilization according to local conditions in order to assure the sustainability of agriculture.