Redox condition and pH are the two most important factors affecting the arsenic (As) form. With changes of arsenic forms, desorption and migration of the soil As are likely to occur. In arid regions, the irrigation can result in the low soil gas permeability. It coupled with large amount of organic matter deposited in sediments can facilitate the formation of the reduction environment, in which iron and manganese oxides are easy to dissolve, and As can be converted into the dissolved forms that move with groundwater. The Qaidam Basin is located in the Qinghai-Tibet Plateau with the highest elevation in China. In the basin, there is little rain, the soil pH is 8, and it belongs to a typical arid region with sparse vegetation and high soil pH. The irrigation makes the agricultural cultivation possible here, but also changes the soil redox conditions, creating a good condition for soil As desorption and migration. It is necessary to clarify the influence of irrigation agriculture on soil As distribution and migration. This study aimed to investigate the soil As distribution and its influential factors. A 13.2 hm2 unreclaimed field was selected from the basin for the study. It was reclaimed for wolfberry cultivation. In the field, soil samples (0-20 cm) were collected from 22 points for soil As content detection before the cultivation, and in 1, 2, and 3 years of cultivation. Meanwhile, the factors related with agricultural activities were investigated and the soil As content in these factors were determined. The results showed that the soil As content was 0-26.4 mg/kg withthe coefficient of variation (CV) of 0.47 before the cultivation, and about 45.5% of soil samples had soil As content exceeding the Green Food production standard of China (20 mg/kg). After 1-3 years of cultivation, the soil As content was clustered about an average of 15.50-15.88 mg/kg, and the numbers of soil samples points exceeding the standard decreased greatly. The Geographic Information Systems (GIS) spatial distribution map of soil As content revealed that the soil As content before the cultivation was high in the northwest and low in the southeast in the plot, an obvious decreasing trend from the northwest to the southeast. With the increase of farming years, the trend was still maintained but not obvious any more. It indicated that the soil arsenic content at depth of 20 cm was in a dynamic equilibrium with the increase of farming years. By calculating the soil As input from pesticides, fertilizers, and irrigation water and output from wolfberry fruits and stalk, the study showed that the soil As net input per year was 250 g/hm2. However, the measured soil As did not increased after 3 years of cultivation. Therefore, soil As may have the other output ways other than fruits collection and stalk. Downward migration of soil As was likely an output way, which was needed for validation in future.%研究灌溉农业对土壤砷的影响因素及影响程度，可以为土壤砷含量、分布变化趋势提供认识依据，继而为地区农产品安全、环境污染风险评估奠定工作基础。选择柴达木盆地一块新开垦枸杞种植田，土地平整后引河水灌溉，种植枸杞。在枸杞种植前及后1～3 a内，定点检测土壤表层（0～20 cm）砷含量，研究其含量及分布变化，并对变化原因和结果进行分析评价。结果表明，原生地土壤砷质量分数为0～26.40 mg/kg，变异系数为0.47，有45.5%的样点超过绿色标准（≤20 mg/kg）。种植1～3 a后与原生地比较，表层土壤砷含量最低值增加，最高值降低，平均质量分数为15.50～15.88 mg/kg，随种植年限增加趋于稳定，样点超过绿色标准率呈下降趋势。GIS空间分布图显示，原生地土壤砷含量高点出现在研究区西北端，低点出现在东南端，整体分布有多层次落差。随着种植年限的增加，原生地的最高和最低分布区域逐渐消失，空间分布层次落差范围逐渐缩小，但仍然保留着原生土壤西北端高、东南端低的固有分布特征。调查统计枸杞种植期间每年有约250 g/hm2土壤砷净输入，然而其实际测定的平均值并没有增加，说明存在其他路径的输出如砷的向下迁移。
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