Removal of phthalic esters from contaminated soil using different cropping systems: A field study

Phytoremediation of phthalic esters (PAE) polluted agricultural soils near electrical-waste dismantling areas in east China is a topic of much public concern. In this study, monocropping and intercropping of alfalfa (Medicago sativa L.), Elsholtzia splendens and Sedum plumbizincicola were compared for their potential in phytoremediation of contaminated soil. Regardless of whether alfalfa was cultivated in monoculture (A) or in combination with E. splendens (AE) or with S. plumbizincicola (AS), and also with all three (AES) in intercropping, concentrations of six PAEs in soil were significantly reduced (p < 0.01) by 87.2, 91.2, 87.2 and 89.4% compared to the control. Intercropping enhanced the decline in soil PAEs and increased soil microbial biomass and microbial functional diversity, and alfalfa shoots and roots took up more of the target pollutants than the other two plant species. DEHP was the most abundant of the target PAEs in soil, roots and shoots. The biological concentration factors (BCFs) of alfalfa in monoculture were relatively high, but the transfer factor (TF) and phytoextraction efficiency, which ranged from 1.16 to 1.69 %, were higher in intercropping systems. Thus, rhizospheric remediation by intercropping of the three-species contributed to PAE removal from the soil and may represent a promising in situ bioremediation strategy for PAE contaminated soils.

► Severe PAEs contamination exists in farmland soils of e-waste recycling site.
► Different planting patterns with 3 test plants were conducted and compared.
► PAEs removal was due to both remediation plant and rhizospheric microbe.
► Alfalfa illustrated great ability in phytoextraction and transfer of PAEs.
► Intercropping patterns of 3 plants showed the best applicability.