摘要
      通过吸附减少土壤中的生物可及抗生素、重金属和抗生素抗性基因（ARGs）是一种有吸引力但尚未实现的降低ARG风险的方法。这种方法有可能降低抗生素和重金属对细菌的（共）选择压力，并降低ARG水平基因向病原体的转化。在这里，通过将水铁矿负载到稻草衍生的生物炭上合成的湿态富硅生物炭/水铁矿复合物（SiC–Fe（W））被检测了i）对土霉素和Cu2+的吸附以降低（共）选择压力，以及ii）对细胞外抗生素抗性质粒pBR322（包含tetA和blaTEM-1）的吸附以抑制ARG转化。SiC–Fe（W）获得了生物炭（对Cu2+）和湿态水铁矿（对土霉素和pBR322）的优先吸附权，并表现出生物炭二氧化硅分散的水铁矿和带负电的生物炭更褶皱和暴露的表面对Cu2+和土霉素的吸附增强作用，对SiC–Fe的吸附能力是土壤的17–135倍。相应地，10 g/kg SiC–Fe（W）改良剂使土壤吸附系数Kd增加了31%–1417%，并降低了溶解土霉素的选择压力、溶解Cu2+的共选择压力和pBR322的转化频率（用大肠杆菌评估）。在碱性条件下，富硅生物炭上Fe–O–Si键的发展增强了水铁矿的稳定性和吸附能力（对土霉素），为生物炭/水铁矿复合合成在ARG污染控制中吸附抑制ARG增殖和转化提供了一种新的潜在策略。
Abstract
Decreasing bioaccessible antibiotics, heavy metals, and antibiotic resistance genes (ARGs) in soil by adsorption is an attractive, but unrealized, approach for ARG risk reduction. This approach has the potential to reduce the (co)selection pressure from antibiotics and heavy metals on bacteria and ARG horizontal gene transformation to pathogens. Here, a wet-state silicon-rich biochar/ferrihydrite composite (SiC–Fe(W)) synthesized by loading ferrihydrite onto rice straw-derived biochar was examined for i) adsorption of oxytetracycline and Cu2+ to reduce (co)selection pressure and ii) adsorption of extracellular antibiotic resistance plasmid pBR322 (containing tetA and blaTEM-1) to inhibit ARG transformation. SiC–Fe(W) gained the adsorption priority of biochar (for Cu2+) and wet-state ferrihydrite (for oxytetracycline and pBR322) and showed adsorptive enhancement (for Cu2+ and oxytetracycline) from a more wrinkled and exposed surface from biochar silica-dispersed ferrihydrite and a more negatively charged biochar, and the adsorption capacity for SiC–Fe(W) was 17–135 times that of soil. Correspondingly, 10 g/kg SiC–Fe(W) amendment increased the soil adsorption coefficient Kd by 31%–1417% and reduced the selection pressure from dissolved oxytetracycline, co-selection pressure from dissolved Cu2+, and transformation frequency of pBR322 (assessed with Escherichia coli). The development of Fe–O–Si bonds on silicon-rich biochar in alkaline enhanced ferrihydrite stability and adsorption capacity (for oxytetracycline), presenting a new potential strategy of biochar/ferrihydrite composite synthesis for adsorptive inhibition of ARG proliferation and transformation in ARG pollution control.

https://www.sciencedirect.com/science/article/abs/pii/S0045653523006239