Evaluation of multiple PRPs' contributions to soil contamination in reclaimed sites around an abandoned smelter

Highlights: • Individual contribution of two smelter owners to soil contamination was evaluated. • Arsenic pollution decreased with increasing distance from the smelter chimney. • Conventional GF evaluation can often distort the individual contribution results. • Pollutants released by the former owner were preserved well in the reclaimed sites. • Field evidences must be prioritized to allocate remediation responsibilities. Although soil contamination must be remediated by the polluters under current legal frameworks in numerous countries, the allocation of responsibilities for soil clean-up is still challenging in the case of multiple potentially responsible parties (PRPs). This study evaluated the individual contributions of two PRPs (Owners A & B) to heavy metal contamination in the soil environment near an abandoned smelter and compared the results with those from the conventional Gore Factor (GF) method. The soil in the study area was widely contaminated by various heavy metals. In particular, the arsenic concentration exceeded the local regulatory level of 25 mg kg⁻¹ at all investigated sites. Arsenic components were frequently observed in the form of iron oxides, and they decreased with increasing distance from the smelter chimney. This distribution supported the premise that the arsenic mainly originated from the chimney through oxidation processes of iron-containing ores under high temperature. The GF results attributed greater responsibility to Owner A than Owner B, while the estimated arsenic masses (based on the field investigation) indicated the contrary. These results could be caused by insufficient information for the GF evaluation, because the change in smelter ownership and long history of contamination obscure important data, such as the amount of total refined ores and the efficiency of air pollution prevention facilities in the smelter. Therefore, more field-based approaches must be considered more importantly for the evaluation of multiple PRPs' remediation responsibilities, especially in areas with long-term contamination.