Soil heavy metal pollution from waste electrical and electronic equipment of repair and junk shops in southern Thailand and their ecological risk.

The waste electrical and electronic equipment (WEEE) stream in Thailand shifted from exporting WEEE to recycling them in domestic enterprises after China's import restrictions on e-waste in 2018. This study aims to investigate the pollution status, pollution sources, and ecological risk of heavy metals from manual WEEE dismantling facilities (12 repair shops and 8 junk shops) in the Nakhon Si Thammarat province of southern Thailand by examining the concentrations of As, Cd, Ni, and Pb in the topsoil (0-15 cm) during the wet and dry seasons. The results revealed that the mean concentrations of all heavy metals were higher during the dry season than in the wet season. The concentrations of analyzed soil heavy metals decreased as the intensity of e-waste dismantling activities increased, with recycling sites > repair sites > control sites (no e-waste recycling activities). Only 10% of WEEE processing workshops (junk shops) had soil Pb and As concentrations that exceeded Thailand's residential soil quality standards. However, ecological indexing models based on the geo-accumulation index found that 75% of electric repair shops were contaminated with the analyzed heavy metals, particularly Pb. Moreover, the Nemerow integrated pollution index indicated that 16.7% of electric repair shops were on the pollution warning line. Our findings suggest that policymakers should promote ecological risk assessment as a method for mitigating the negative environmental impact of electronic repair businesses, which are widely dispersed in residential areas and tend to dominate the WEEE stream because of the circular economy concept of "right to repair", and highlight the decline of junk shops and e-waste dismantling villages for waste export resulting from China's ban.