Purpose This study aimed to reveal the effect of dissolved organic matter (DOM) from organic amendments on the mobilization and transport of Cd, both in dissolved form and colloid-associated form, in arable soil in the vicinity of a metallic mining area. Materials and methods Leaching experiments were conducted in an intact soil column in the absence and presence of pig manure-derived DOM under saturated conditions with a rate of 45.9 mm/h to explore the transport dynamic and potential of total Cd (CdTotal), colloid-associated Cd (CdColloid) and dissolved Cd (CdDissolved). Pearson correlation, multi-linear regression and redundancy analysis were used in combination to reveal the mechanism of the dynamic variation of physicochemical factors in response to soil leaching on Cd transport. Results and discussion Soil colloid was found to be the major carrier for Cd transport during leaching in the absence of manure DOM and it dominated the transport dynamics of CdTotal and CdColloid. The presence of manure DOM largely improved the transport potential of Cd in soil, with an increase by mean factors of 1.76 and 2.24 for the leached mass of CdTotal and CdColloid, respectively. Solution pH became the dominant factor determining the transport dynamics of CdTotal and CdColloid in the presence of manure DOM. The increase of solution pH following the injection of manure DOM induced the mobilization of soil colloid, which further led to the increased leached mass of CdColloid. Additionally, the resultant modification of surface negative potential especially of fine colloids by manure DOM improved the enrichment factor of Cd on soil colloid (EFCd/colloid) from 32.6 mg/kg to 43.4 mg/kg, which was the major mechanism for the intensified dominant role of soil colloid in the transport of Cd in soil in the presence of manure DOM. Conclusions These findings highlighted the critical role of manure DOM in the intensified mobilization of soil colloids as well as the transport of Cd in soil upon leaching mainly through the elevation of solution pH and EFCd/colloid, providing new insights in shallow groundwater protection in the vicinity of mining areas and/or site remediation scenarios elsewhere.

Manure-derived dissolved organic matter enhanced colloid-facilitated transport of Cd in arable soil in the vicinity of a mining area

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发表日期：

2025年7月5日

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Wei Zhang,
Mengbin Hou,
Shiyu Wu,
Shuai Chen,
Xingmin Wang

摘要

Purpose

This study aimed to reveal the effect of dissolved organic matter (DOM) from organic amendments on the mobilization and transport of Cd, both in dissolved form and colloid-associated form, in arable soil in the vicinity of a metallic mining area.

Materials and methods

Leaching experiments were conducted in an intact soil column in the absence and presence of pig manure-derived DOM under saturated conditions with a rate of 45.9 mm/h to explore the transport dynamic and potential of total Cd (Cd_Total), colloid-associated Cd (Cd_Colloid) and dissolved Cd (Cd_Dissolved). Pearson correlation, multi-linear regression and redundancy analysis were used in combination to reveal the mechanism of the dynamic variation of physicochemical factors in response to soil leaching on Cd transport.

Results and discussion

Soil colloid was found to be the major carrier for Cd transport during leaching in the absence of manure DOM and it dominated the transport dynamics of Cd_Total and Cd_Colloid. The presence of manure DOM largely improved the transport potential of Cd in soil, with an increase by mean factors of 1.76 and 2.24 for the leached mass of Cd_Total and Cd_Colloid, respectively. Solution pH became the dominant factor determining the transport dynamics of Cd_Total and Cd_Colloid in the presence of manure DOM. The increase of solution pH following the injection of manure DOM induced the mobilization of soil colloid, which further led to the increased leached mass of Cd_Colloid. Additionally, the resultant modification of surface negative potential especially of fine colloids by manure DOM improved the enrichment factor of Cd on soil colloid (EF_Cd/colloid) from 32.6 mg/kg to 43.4 mg/kg, which was the major mechanism for the intensified dominant role of soil colloid in the transport of Cd in soil in the presence of manure DOM.

Conclusions

These findings highlighted the critical role of manure DOM in the intensified mobilization of soil colloids as well as the transport of Cd in soil upon leaching mainly through the elevation of solution pH and EF_Cd/colloid, providing new insights in shallow groundwater protection in the vicinity of mining areas and/or site remediation scenarios elsewhere.