In situ remediation and ex situ treatment practices of arsenic-contaminated soil: An overview on recent advances

Soil arsenic pollution issues have received increasing attention over the past decades. This review focuses on recent advances in remediation practices of arsenic-contaminated soils from 7400 articles. It critically evaluates the significant literatures of the various methods and proposes research trends and hotspots through bibliometric analysis. Soils or other sites remediation technology could be divided into two categories: ones having received in situ remediation and ones subjected to ex situ treatments. Among them, this review classifies the in situ remediation technology of arsenic-contaminated soils into extraction/migration, immobilization/stabilization, and transformation/degradation from the perspective of remediation goals. From the perspective of treatment pathways, the ex situ treatment technologies for arsenic-contaminated soils are divided into soil washing and solidification/stabilization. Various remediation methods present different levels of adaptability. By introducing six tolerance indices, the adaptability of all the arsenic-contaminated soil remediation technologies to contamination level, costs, time, efficiency, the existence of co-pollutants, and secondary pollution risks is proposed. Solidification/stabilization is considered as the most efficient and the most cost effective is the phytoextraction technique. The research hotspot and trend in the field of arsenic-contaminated soil remediation is the application of biochar-related amendments in paddy soils.