Adsorption Characteristics and the Effect of Dissolved Organic Matter on Mercury(II) Adsorption of Various Soils in China

ABSTRACT

To evaluate the adsorption characteristics and effects of dissolved organic matter (DOM) from wheat straw (DOM_W) and swine manure (DOM_S) on mercury [Hg(II)] adsorption by soils, a series of experiments was conducted on 26 soils with different soil properties.Results showed that the values of K_d (a solid–liquid partition coefficient) of soils varied within a range of 0.768–14.386 L g⁻¹. K_d values were mainly controlled by soil organic matter (SOM), cation exchange capacity (CEC), soil nitrogen (N), and soil sulfur (S). When DOM_W and DOM_S were added to the soil samples, the amount of Hg(II) adsorbed by the soils decreased significantly. Furthermore, based on the decreased percentage of adsorption of Hg(II) by soil upon adding DOM_W (P_DOMW) or DOM_S (P_DOMS), about 73.08% soils, the values of P_DOMS were smaller than those of P_DOMW. The P_DOMW values were related to SOM, pH, free Fe oxide content, and CEC, whereas P_DOMS values were related to soil free Fe/Al oxide contents. Therefore, we should pay more attention about mercury risk caused by the addition of exogenous organic matter in soils, especially for the soils with low or high pH, less SOM, low CEC, and less free Fe/Al oxide.

KEYWORDS:

• Distribution coefficient
• soil properties
• sorption
• fate
• various soils

Acknowledgments

The authors are grateful to Professor Yongguan Zhu, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences; and Wei Guo, Shandong University, for their assistance in soil sampling. Furthermore, they wish to thank Denise A. Leonard and the reviewers for comments on the manuscript.

Funding

The research was supported by the Key Industry Key Technology Innovation Project of Shandong Province (No. 2016CYJS05A02), The Fundamental Research Funds of Shandong University (No. 2014JC048), the China Postdoctoral Science Foundation (No. 2015M572016), and Shandong Provincial Natural Science Foundation, China (No. ZR2013CM042).