Health assessment of spatial and temporal distribution of arsenic in soils irrigated with reclaimed water.

Reclaimed water is an important water resource for agricultural irrigation. Based on the systematic analysis of experimental data, this paper studies the spatiotemporal transformation and distribution of As in soil-crop system. Through the comparison with groundwater irrigation, reclaimed water irrigation was tested and studied in connection with the greenhouse vegetables in the growing season. The accumulation, distribution and transportation of As in different depths of soil within 7 days after reclaimed water irrigation were analyzed and discussed. The results showed that the concentration of As was the highest on the first day after irrigation; it was the highest at the depth of 100 cm on the third day after irrigation, but its concentration in the topsoil slightly decreased; from the fifth to the seventh day, the concentrations of As in the different layers of soil were almost the same, but it was the highest at the depth of 80-120 cm; and it decreased slightly with the increase in depth when the depth was less than 120 cm. As in soil during the growing season varied as the frequency of irrigation increased. The specific situation was as follows: as the accumulated As in the topsoil increased, the increased As at the depth of 80-120 cm would become less and the concentration of As at 200 cm would fall. Therefore, when the appropriate concentration of reclaimed water is used for irrigation, the concentration of As in the deep layer soil will comply with the standard limits of GB15618-1995 and the irrigation with reclaimed water of appropriate concentration will not cause As pollution.