Cleaning heavy metal contaminated soil with soluble humic substances instead of synthetic polycarboxylic acids

TY - JOUR

T1 - Cleaning heavy metal contaminated soil with soluble humic substances instead of synthetic polycarboxylic acids

AU - Borggaard, Ole K.

AU - Holm, Peter Engelund

AU - Jensen, Julie Katrine

AU - Soleimani, Mohsen

AU - Strobel, Bjarne W.

PY - 2011/9

Y1 - 2011/9

N2 - Soils contaminated with heavy metals constitute a serious and widespread ecological problem but to clean such soils requires strong chemicals such as polycarboxylates; frequently ethylenediaminetetraacetic acid and nitrilotriacetic acid are used. However, these compounds are synthetic and toxic and their replacement by natural products such as soluble humic substances as washing agents for cleaning heavy metal polluted soils would be environmentally very attractive. In fact, such a replacement seems possible at least on cadmium and copper contaminated soil inasmuch as humic substances, depending on the concentration, were found to extract up to 45% and 54% of total cadmium and copper from a highly contaminated calcareous soil. Even though higher amounts of the two metals were extracted by ethylenediaminetetraacetic acid and nitrilotriacetic acid, the humic substances undoubtedly extracted the most reactive fractions. However, the humic substances extracted only 4% of total lead and 17% of total nickel, whereas the percentages for the synthetic polycarboxylates were about 30% for nickel and lead. Ethylenediaminetetraacetic acid and nitrilotriacetic acid may therefore be replaced by humic substances as washing agents for cadmium, copper and maybe nickel contaminated soils, whereas they seem unsuited for cleaning lead contaminated soils, at least if the soils are as calcareous as the soil tested.

AB - Soils contaminated with heavy metals constitute a serious and widespread ecological problem but to clean such soils requires strong chemicals such as polycarboxylates; frequently ethylenediaminetetraacetic acid and nitrilotriacetic acid are used. However, these compounds are synthetic and toxic and their replacement by natural products such as soluble humic substances as washing agents for cleaning heavy metal polluted soils would be environmentally very attractive. In fact, such a replacement seems possible at least on cadmium and copper contaminated soil inasmuch as humic substances, depending on the concentration, were found to extract up to 45% and 54% of total cadmium and copper from a highly contaminated calcareous soil. Even though higher amounts of the two metals were extracted by ethylenediaminetetraacetic acid and nitrilotriacetic acid, the humic substances undoubtedly extracted the most reactive fractions. However, the humic substances extracted only 4% of total lead and 17% of total nickel, whereas the percentages for the synthetic polycarboxylates were about 30% for nickel and lead. Ethylenediaminetetraacetic acid and nitrilotriacetic acid may therefore be replaced by humic substances as washing agents for cadmium, copper and maybe nickel contaminated soils, whereas they seem unsuited for cleaning lead contaminated soils, at least if the soils are as calcareous as the soil tested.

U2 - 10.1080/09064710.2010.515602

DO - 10.1080/09064710.2010.515602

M3 - Journal article

SN - 0906-4710

VL - 61

SP - 577

EP - 581

JO - Acta Agriculturae Scandinavica. Section B. Soil and Plant Science

JF - Acta Agriculturae Scandinavica. Section B. Soil and Plant Science

IS - 6

ER -