The possible use of soluble humic substances for remediation of heavy metal polluted soils

TY - ABST

T1 - The possible use of soluble humic substances for remediation of heavy metal polluted soils

AU - Borggaard, Ole K.

AU - Jensen, Julie Katrine

AU - Holm, Peter Engelund

AU - Strobel, Bjarne W.

AU - Hansen, Hans Christian Bruun

N1 - Conference code: 3

PY - 2008

Y1 - 2008

N2 - Polluted soil is a common and serious environmental problem. While reliable methods exist for cleaning soil contaminated by organic compounds through degradation, remediation of heavy metal polluted soils awaits an appropriate solution. This is because heavy metals are nondegradable and generally strongly bonded in soils. Consequently, removal of heavy metals by extraction is difficult and requires harsh chemicals such as ethylenediaminetetraacetic acid (EDTA) and acids. However, use of EDTA is environmentally problematic because of persistence, toxicity and deterioration of soil structure. Therefore, the potential of soluble natural humic substances (HS) to extract heavy metals from contaminated soils is tested as an environmental friendly substitute for EDTA. A strongly polluted urban soil and a moderately polluted agricultural soil were extracted at neutral pH in batch mode by three HS solutions from beech and Norway spruce litter and processed cow slurry, all containing 25 mM dissolved organic carbon (DOC). After 10 weeks, 8 % to 39 % of the total Cd, Cu, Ni and Pb soil contents were extracted. Increasing the DOC concentration to 100 mM resulted in markedly increased heavy metals extraction. Heavy metal extraction with dissolved HS is compared with EDTA at the same concentration and sequential extraction has been performed to identify extracted pools. The results indicate a clear potential of using HS solutions for remediation of heavy metal polluted soils, which is fortunate, especially if organic waste products such as sewage sludge and animal slurry after proper processing can be turned into soluble HS as preliminary investigations indicate.

AB - Polluted soil is a common and serious environmental problem. While reliable methods exist for cleaning soil contaminated by organic compounds through degradation, remediation of heavy metal polluted soils awaits an appropriate solution. This is because heavy metals are nondegradable and generally strongly bonded in soils. Consequently, removal of heavy metals by extraction is difficult and requires harsh chemicals such as ethylenediaminetetraacetic acid (EDTA) and acids. However, use of EDTA is environmentally problematic because of persistence, toxicity and deterioration of soil structure. Therefore, the potential of soluble natural humic substances (HS) to extract heavy metals from contaminated soils is tested as an environmental friendly substitute for EDTA. A strongly polluted urban soil and a moderately polluted agricultural soil were extracted at neutral pH in batch mode by three HS solutions from beech and Norway spruce litter and processed cow slurry, all containing 25 mM dissolved organic carbon (DOC). After 10 weeks, 8 % to 39 % of the total Cd, Cu, Ni and Pb soil contents were extracted. Increasing the DOC concentration to 100 mM resulted in markedly increased heavy metals extraction. Heavy metal extraction with dissolved HS is compared with EDTA at the same concentration and sequential extraction has been performed to identify extracted pools. The results indicate a clear potential of using HS solutions for remediation of heavy metal polluted soils, which is fortunate, especially if organic waste products such as sewage sludge and animal slurry after proper processing can be turned into soluble HS as preliminary investigations indicate.

M3 - Conference abstract in proceedings

SP - 80

EP - 81

BT - Abstracts, EUROSOIL CONGRESS 2008

T2 - International EUROSOIL Congress 2008

Y2 - 26 August 2008 through 29 August 2008

ER -