文献名： Biological aqua crust mitigates metal (loid) pollution and the underlying immobilization mechanisms

作者 ： Guobao Wang ^a ， Yongqiang Yuan ^abc ， Jean louis Morel ^d ， Zekai Feng ^a ， Daijie Chen ^a ， Chunfeng Lu ^a ， Meina Guo ^a ， Chong Liu ^a ， Shizhong Wang ^abc ， Yuanqing Chao ^abc ， Yetao Tang ^abc ， Dongye Zhao ^e ， Shi Xiao ^f ， Weixian Zhang ^g ， Rongliang Qiu ^abh

^a School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou, 510006, China

^b Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Sun Yat-sen University, Guangzhou, 510275, China

^c Guangdong Provincial Engineering Research Center for Heavy Metal Contaminated Soil Remediation, Sun Yat-sen University, Guangzhou, 510006, China

^d Laboratoire Sols et Environnement, UMR 1120, Université de Lorraine, INRAE, 54518 Vandoeuvre-lès-Nancy, France

^e Environmental Engineering Program, Department of Civil & Environmental Engineering, Auburn University, Auburn, AL 36849, USA

^f School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China

^g College of Environmental Science and Engineering, State Key Laboratory of Pollution Control and Resources Reuse, Tongji University, Shanghai 200092, China

^h Guangdong Laboratory for Lingnan Modern Agriculture, College of Natural Resources and Environment, South China Agricultural University, Guangzhou 510642, China

摘要： Biocrust-mediated in situ  bioremediation could be an alternative strategy to mitigate metal(loid) pollution in aquatic habitats. To better understand the roles of biocrusts in regulating the fate of metal(loid)s, we examined the morphology, composition and structure of biological aqua crusts (BAC) developed in the mine drainage of a representative Pb/Zn tailing pond, and tested their effectiveness for immobilizing typical metal(loid)s. Unlike terrestrial biocrusts, BAC results from an assembly of compounds produced by the strong microbial activity and mineral compounds present in the aquatic environment. The BAC exhibited a unique flexible, spongy and porous structure with a specific surface area of 12-22 m ²  g ⁻¹ , and was able to effectively concentrate various metal(loid)s ( e.g.  Cd, 0.26-0.60 g kg ⁻¹ ; Pb, 0.52-0.66 g kg ⁻¹ ; As, 10.4-24.3 g kg ⁻¹ ). The concentrations of metal(loid)s ( e.g.  Cd and As) in the BAC were even three to seven times higher than those in the source tailings, and more than 98% of immobilized metal(loid)s were present as the highly stable non-EDTA-exchangeable fraction. Adsorption on the well distributed micro-particles of the clay minerals ( e.g.  kaolinite) and the organic matters (2.0-2.7 wt.%) were found to be the major mechanisms for BAC to bind metal cations, whereas adsorption and coprecipitation on Fe/Mn oxide ( e.g.  FeOOH), was proposed to be the dominant pathway for accumulating metal(loid)s, especially As. The decrease in aqueous concentrations of the metal(loid)s along the drainage could be attributed in part to the scavenging effects of the BAC. These findings therefore provide new insights into the possible and efficient strategy for metal(loid) removal from water bodies, and highlighted the important role of BAC as a nature-based solution to benefit the bioremediation of mining area.

关键词： Biological aqua crust ， Metal(loid) immobilization， Biological filter ， Mine drainage ， Bioremediation