Mobility and environmental availability of metal(loid)s at a historically recultivated Cu/Pb smelter site in Polichno, Holy Cross Mountains, Poland

Abstract

Abstract This study investigates the long-term effects of partial recultivation on metal(loid) contamination and environmental risks at the historical (14-17th century) Cu–Pb smelting site at Polichno (Holy Cross Mountains, Poland). More than 50 years ago, the site underwent partial recultivation involving slag removal; however, residual slag fragments remain dispersed throughout the soil profile. The slag contains high mean concentrations of metal(loid)s, including 111,000 mg·kg − 1 Pb, 56,300 mg·kg − 1 Ba, 8370 mg·kg − 1 Zn, 465 mg·kg − 1 Cu, 110 mg·kg − 1 As, mainly hosted in sulfides, arsenides, sulfates, and a glassy matrix. Maximum soil concentrations reached 7010 mg∙kg − 1 Pb, 4180 mg∙kg − 1 Ba, 1500 mg∙kg − 1 Zn, 658 mg∙kg − 1 Cu, 45.4 mg∙kg − 1 As, with the highest levels in ash- and wood-containing horizons. Average pore water concentrations were 115 µg∙l − 1 Pb, 166 µg∙l − 1 Ba, 161 µg∙l − 1 Zn, 58.9 µg∙l − 1 Cu, and 1.9 µg∙l − 1 As. Batch leaching tests using deionized water classified the slag as non-hazardous waste rather than inert waste, as Pb release exceeded the regulatory threshold for inert waste. pH-static tests showed peak mobilization at pH 2 (Ba 39,000 mg·kg − 1 , Pb 4860 mg·kg − 1 , Zn 3870 mg·kg − 1 , As 21.7 mg·kg − 1 ), with minima at neutral pH. The formation of secondary phases during leaching indicates immobilization processes that limit metal(loid) mobility.