Health evaluation on migration and distribution of heavy metal Cd after reclaimed water drip irrigation.

The utilization of reclaimed water is one of the effective measures to save water resources. The study of reclaimed water irrigation and the analysis of how heavy metals migrate in the soil, especially their movement laws, have important theoretical and practical significance. It helps to predict the risk of heavy metals in foods, which protects our health and safety. In this paper, we studied the accumulation and distribution of heavy metal Cd in soils with reclaimed water drip irrigation in greenhouses during growing season, comparing the effects with groundwater drip irrigation. The results show that the Cd concentration in the surface soil is the highest on the second day after drip irrigation. It will be the highest on the fourth day in the depth of 100 cm, and then, it will decrease slightly. During the period of the sixth day to the eighth day, the Cd concentrations are similar in each depth, and it is the highest in the depth of 0-40 cm and 80-120 cm, but the Cd concentration decreases with the lower depth below 120 cm. By utilizing proper ways of reclaimed water drip irrigation, the Cd concentration in the deep soil will not violate the standard limits of GB15618-1995, which will not cause Cd pollution.