The risk element contamination level in soil and vegetation at the former deposit of galvanic sludges

Abstract

Hazardous waste deposits with high contents of risk elements can represent a potential environmental hazard via penetration of these elements into soil and vegetation. In this case, the former deposit of galvanic sludges in Dolni Lipka, Czech Republic, was investigated. The deposit was temporarily remediated by a thick soil layer cover. The total and mobile risk element contents were determined within the profile of the soil cover as well as the element contents in the vegetation growing on the cover to assess the potential environmental threat of the deposit The plant samples were collected from nine sampling areas, each of 3 × 3 m. The stratification of risk elements within the soil profile was determined where the soil samples were collected in depths of 0–10, 10–40, 40–70, 70–100, and 100–140 cm. The total element contents were determined in aboveground biomass and roots of selected plant species and pseudo total content (extractable with aqua regia) in soils. The mobilizable pool of elements in soils was determined after extraction with a 2 mol L−1 solution of HNO3 and a plant-available pool of elements after extraction with 0.11 mol L−1 solution of CH3COOH. From the perspective of the vegetation and soil’s risk elements content, the dump did not meet criteria for a safe hazardous waste landfill in any way during the sampling time. According to the results, the elements can be divided into three groups: (i) low levels of elements within whole profile—As and Cr; (ii) high levels of elements concentrated in the deepest layer of the soil without significant penetration of the upper layers—Cu, Mo, Pb, Ni, and Zn; and (iii) the elements penetrating the upper layers of the soil—Cd and Hg. The third case poses a serious environmental risk requiring more intensive investigation on the bioavailability of these elements at the site, and subsequently, permanent remediation of the deposit.