TY - JOUR
T1 - Evaluation of heavy metal availability in soils near former zinc smelters by chemical extractions and geochemical modelling
AU - Gao, Hui
AU - Koopmans, Gerwin F.
AU - Song, Jing
AU - Groenenberg, Jan E.
AU - Liu, Xinyang
AU - Comans, Rob N.J.
AU - Weng, Liping
PY - 2022/10/1
Y1 - 2022/10/1
N2 - Multi-surface modelling (MSM) is an important tool to predict heavy metal partitioning and speciation in soils. However, calcareous clay soils contaminated by smelting activities and mine waste have so far received little attention in MSM studies. In this work, 6 paired soil samples taken nearby former Zn smelters and at further distance were used for quantifying the essential input parameters for MSM including the size of the geochemically reactive pool of heavy metals and the reactivity of soil organic matter (SOM) for metal binding. The reactive heavy metal pool (Cd, Cu, Ni, Pb, and Zn) in these samples was determined by extracting soil with 0.43 M HNO3 and 0.005 M DTPA. For both extraction methods, the contribution of all heavy metals to their total contents was larger in most of the soil samples taken nearby former Zn smelters than in the paired samples from further distance. Furthermore, the amounts of heavy metals extracted with 0.43 M HNO3 were consistently larger than those extracted with 0.005 M DTPA. The sum of the humic acid (HA), fulvic acid (FA) + hydrophobic organic neutral (HON) fraction varied between 6.2 and 43% of total SOM with an average of 24%, which is at the lower end of what is commonly reported in literature. The lower SOM reactivity might be attributed to a lower humification rate of fresh soil organic matter due to heavy metal contamination. The accuracy of the MSM-predicted predictions of solubility of the heavy metals, especially for Ni and Zn, was higher when the results of the DTPA extraction method were used as model input, than when using the results of the HNO3 extraction method, especially when the soil carbonate content was > 4%. Hence, the measurement of the geochemical reactivity of heavy metals by the 0.005 M DTPA extraction method and the reactivity of SOM enable adequate MSM predictions of the solubility of heavy metals in smelter slag-contaminated calcareous clay soils.
AB - Multi-surface modelling (MSM) is an important tool to predict heavy metal partitioning and speciation in soils. However, calcareous clay soils contaminated by smelting activities and mine waste have so far received little attention in MSM studies. In this work, 6 paired soil samples taken nearby former Zn smelters and at further distance were used for quantifying the essential input parameters for MSM including the size of the geochemically reactive pool of heavy metals and the reactivity of soil organic matter (SOM) for metal binding. The reactive heavy metal pool (Cd, Cu, Ni, Pb, and Zn) in these samples was determined by extracting soil with 0.43 M HNO3 and 0.005 M DTPA. For both extraction methods, the contribution of all heavy metals to their total contents was larger in most of the soil samples taken nearby former Zn smelters than in the paired samples from further distance. Furthermore, the amounts of heavy metals extracted with 0.43 M HNO3 were consistently larger than those extracted with 0.005 M DTPA. The sum of the humic acid (HA), fulvic acid (FA) + hydrophobic organic neutral (HON) fraction varied between 6.2 and 43% of total SOM with an average of 24%, which is at the lower end of what is commonly reported in literature. The lower SOM reactivity might be attributed to a lower humification rate of fresh soil organic matter due to heavy metal contamination. The accuracy of the MSM-predicted predictions of solubility of the heavy metals, especially for Ni and Zn, was higher when the results of the DTPA extraction method were used as model input, than when using the results of the HNO3 extraction method, especially when the soil carbonate content was > 4%. Hence, the measurement of the geochemical reactivity of heavy metals by the 0.005 M DTPA extraction method and the reactivity of SOM enable adequate MSM predictions of the solubility of heavy metals in smelter slag-contaminated calcareous clay soils.
KW - Chemical extraction
KW - Heavy metals
KW - Mining activities
KW - Multi-surface modelling
KW - Organic matter fractionation
KW - Soil contamination
U2 - 10.1016/j.geoderma.2022.115970
DO - 10.1016/j.geoderma.2022.115970
M3 - Article
AN - SCOPUS:85131379182
SN - 0016-7061
VL - 423
JO - Geoderma
JF - Geoderma
M1 - 115970
ER -