Enhancing phytoremediation of arsenic-contaminated soil by agronomic practices (drip irrigation and intercropping): Influence of soil organic matter

It is essential to improve the efficiency and economic benefits of phytoremediation. In this study, drip irrigation and intercropping were used to enhance the phytoremediation of arsenic-contaminated soil. Meanwhile, the influence of soil organic matter (SOM) on phytoremediation was investigated by comparing the difference in arsenic migration in soils with or without peat addition as well as the arsenic accumulation of plants. The results showed that hemispherical wetted bodies with a radius of approximately 6.5 cm were formed in the soil after drip irrigation. Arsenic in the center of the wetted bodies migrated to the edge of the wetted bodies. Peat inhibited the upward migration of arsenic from the deep subsoil and increased the phytoavailability of arsenic under drip irrigation conditions. To soils without peat added, drip irrigation decreased the arsenic accumulation in crops (planted at the center of the wetted body) while increased the arsenic accumulation in remediation plants (planted at the edge of the wetted body) compared with the flood irrigation treatment. An increase in soil organic matter of about 36 % was found after mixing 2 % peat in the soil, and correspondingly, arsenic concentrations in remediation plants increased by >28 % in both intercropping treatments with a drip or flood irrigation. Drip irrigation coupled with intercropping enhanced the effect of phytoremediation, and the addition of soil organic matter further improved phytoremediation efficiency.