选择柴达木盆地诺木洪农场3种类型农田进行20 cm表层土壤砷（As）含量检测。第1种为新开垦原生地，第2种为20年耕种地，第3种为50年耕种地，检测As含量分别为16.29、14.90、14.04 mg·kg-1。3种土壤As含量均达到无公害食品标准（25 mg· kg-1）和绿色食品标准（20 mg·kg-1）。多年耕种并没有造成农田表层土壤As积累。农田灌溉用河水中未检出As。生产中使用的22种农药、肥料均检测到As，其中15种杀虫剂、杀真菌剂、除草剂、植物激素等，每年输入土壤As 4513.59 mg·hm-2；7种肥料每年输入土壤As 258015.24 mg·hm-2。施肥是土壤中As输入的重要来源，最主要的输入源是磷酸二铵，占到50％；其次为复合肥、鸡粪和有机肥。每年随作物输出As总量为4380 mg·hm-2。模拟田间灌溉，进行土壤柱淋漓试验，农田20 cm表层土壤每年随灌溉淋漓输出As为245230.65 mg·hm-2，这与随着肥料、农药输入量几乎相等。表层土壤As处在一个输入、输出相对稳定的动态平衡状态。从土壤中输出的As，随灌溉水输入到水系统中，继而造成水系统As的积累，最终将影响到地区农业的可持续发展。%The topsoil arsenic of three wolfberry farmland in the Nuomuhong Farm located in the Qaidam Basin, western China,was detected in this study. The first farmland was an original land, which had never been farmed, the second one was a farmland which had been farmed for 20 years and the third one was a farmland which had been farmed for 50 years. The arsenic contents of those three farmlands were 16.29, 14.90 mg·kg-1 and 14.04 mg·kg-1, respectively. All of them were up to meet the Pollution-Free Food(25 mg·kg-2)and the Green Food(20 mg·kg-1) standards. Farming for many years did not cause the accumulation of farmland topsoil arsenic. Irrigation water was found to be free of arsenic. Fifteen kinds of pesticides, fungicides, herbicides and plant hormones contributed 4 513.59 mg·hm-2 of arsenic to the soil per year. Seven kinds of fertilizer contributed 258 015.24 mg·hm-2 of arsenic to the soil per year. Fertilization was thus a major source of arsenic pollution in the soil, the most serious source of pollution was DAP(50%), followed by compound fertilizer, chicken manure and organic fertilizer. Total 4 380 mg·hm-2 arsenic was output with crops per year. In the experiments of field irrigation simulation and dripping wet the soil, there were 245 230.65 mg·hm-2 arsenic output from 20 cm topsoil by irrigation dripping per year, but the same amount of arsenic were input topsoil with fertilizers and pesticides per year. Farmland topsoil arsenic was an input-output homeostasis state. The arsenic that output from the soil en-tered and accumulated in water system with irrigation water, ultimately affected the sustainable development of agriculture in the region.
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