摘要
为探究土壤铁对厌氧砷氧化耦合硝酸盐还原过程的作用机制,选取土壤有机质含量相近但铁含量不同的两种稻田土壤,设置对照、+NO_(3)^(-)、+As(Ⅲ)和+As(Ⅲ)+NO_(3)^(-)处理开展厌氧培养实验,研究As/N/Fe及微生物群落的变化.结果表明,厌氧条件下硝酸盐还原驱动砷氧化过程,低铁和高铁土壤中砷氧化率分别为35.3%和43.0%,高铁土壤的磷酸提取态和草酸提取态砷占比显著高于低铁土壤;As(Ⅲ)的存在减慢NO_(3)^(-)还原,减少NO_(2)^(-)和N_(2)O的积累,促进NH_(4)^(+)的生成,高铁土壤的反硝化和异化硝酸盐还原产铵过程比低铁土壤快;硝酸盐和As(Ⅲ)的存在降低土壤溶解态和吸附态Fe(Ⅱ)的浓度,提高吸附态总铁的浓度,并改变微生物群落的组成和丰度,Bacillus、Clostridium和Planococcaceae在硝酸盐还原及砷氧化过程中占主导.因此,当土壤吸附态铁高时,能加速砷氧化耦合反硝化/异化硝酸盐还原产铵过程,并促进土壤铁氢氧化物对As(Ⅲ)和As(V)的固定.上述研究发现可为淹水期稻田土壤砷转化的铁氮元素调控提供科学依据.
In this study,two paddy soils with similar organic matter contents but different iron contents were used to conduct anaerobic microcosm incubation experiments with four treatments,including Control,+NO_(3)^(-),+As(Ⅲ),and+As(Ⅲ)+NO_(3)^(-).The transformation of arsenic,nitrogen,and iron species,as well as changes in microbial community structure and abundance were investigated in order to elucidate the effect of iron on the microbial As(Ⅲ)oxidation coupling nitrate reduction processes in soils under anoxic conditions.The results revealed that As(Ⅲ)oxidation was driven by nitrate reduction,and 35.3%and 43.0%of As(Ⅲ)were oxidized in the soils with low iron and high iron content,respectively,at the end of incubation.The phosphate-extracted and oxalate-extracted arsenic contents were significantly higher in the soil with high iron content than those in the soil with low iron content.The presence of As(Ⅲ)slowed down the nitrate reduction process,reduced the accumulation of NO_(2)^(-)and N_(2)O,and promoted the NH_(4)^(+)production.In addition,the denitrification and dissimilatory nitrate reduction to ammonium(DNRA)processes were faster in the soil with high iron content than those in the soil with low iron content.The presence of nitrate and As(Ⅲ)decreased the concentrations of dissolved Fe(Ⅱ)and adsorbed Fe(Ⅱ)in soils,increased the concentrations of adsorbed total iron,and altered the composition and abundance of soil microbial community.Bacillus,Clostridium,and Planococcaceae were identified as the dominant bacteria during nitrate reduction and As(Ⅲ)oxidation processes.This study demonstrates that soils with high content of adsorbed iron can facilitate anaerobic As(Ⅲ)oxidation coupling denitrification/DNRA and enhance the immobilization of As(Ⅲ)and As(V)by iron(oxyhydr)oxides in soils.These findings provide scientific basis for the regulation of arsenic transformation by iron and nitrogen elements in flooded paddy fields.
作者
牛汝苗
杨光
高一帆
梁露予
潘丹丹
黄国勇
李晓敏
NIU Ru-miao;YANG Guang;GAO Yi-fan;LIANG Lu-yu;PAN Dan-dan;HUANG Guo-yong;LI Xiao-min(Key Laboratory of Theoretical Chemistry of Environment,Ministry of Education,Guangdong Provincial Key Laboratory of Chemical Pollution and Environmental Safety,Environmental Research Institute,South China Normal University,Guangzhou 510006,China;Guangdong Provincial Key Laboratory of Integrated Agro-environmental Pollution Control and Management,National-Regional Joint Engineering Research Center for Soil Pollution Control and Remediation in South China,Institute of Eco-environmental and Soil Sciences,Guangdong Academy of Sciences,Guangzhou 510650,China)
出处
《中国环境科学》
北大核心
2025年第3期1456-1464,共9页
China Environmental Science
基金
国家自然科学基金资助项目(42377239,42207009)
广东省重点实验室开放基金资助项目(2023B1212060044)。
关键词
铁氧化还原
反硝化
异化硝酸盐还原成铵
微生物群落
砷氧化固定
iron redox
denitrification
dissimilatory nitrate reduction to ammonium(DNRA)
microbial community
arsenic oxidation and immobilization
