Risk estimation of multi-polluted soils in contact with lacustrine systems

Abstract: The area of "Norra Hamnstaden" in Lidköping has been used for several different industires for more than 100 years and porcelain has been produced there since 1912. The sub-area studied in this thesis has been used as a landfill for industrial waste including waste from the local porcelain factory, Rörstrand. Lead is a common contaminant in ceramic waste since the favorable properties of lead(II) oxide has made it a common component in porcelain glazes. Previous surveys have shown severe contamination with levels of lead up to 20 g/kg in the area, but they have been performed to get an overview. Since there are plans for housing and parks on the site, the risk for future inhabitants needs to be assessed more thoroughly. When the theoretical environmental impact of an element in the soil environment is evaluated, only its total concentration in the fine (<2 mm) fraction of the matrix is considered and the availability is assumed to be 100%. For a better understanding of the environmental impact from the soil in the area, a sequential leaching was performed to reveal the chemical speciation and availability of the elements. Analyses of water soluble elements, inorganic anions and total concentrations were also performed. Since the area contains a large amount of porcelain residues and other industrial waste which do not pass through a 2 mm sieve, the coarse fraction was crushed and analyzed as well. The sampling revealed that the main filling of a part of the area was porcelain and porcelain related waste. The lead contamination was severe at those sampling points where porcelain was found, and remediation is needed in that area. The water leachable lead was up to 521 μg/L or 6.2 mg/kg. The total concentration of lead exceeded the limit value for hazardous waste at five sampling points where it reached 52 g/kg. The sequential leaching showed that the total concentration of lead was a good estimate for its bioavailable concentration. For the risk controlling elements almost 50 % of the results showed a significant statistical difference between the bioavailable and the total concentration. The coarse fraction contained lower lead concentration than the fines and the total concentrations therefore overestimate the risk. Moving the porcelain masses could be the best option for remediation unless it can be motivated to leave them in the area.