舒瑶,弓晓峰,李远航,熊捷迁,孙玉恒,牛丹妮,吴莉,林媛.鄱阳湖湿地DOM对铁还原菌异化还原水铁矿的影响[J].环境科学学报,2021,41(7):2814-2825
鄱阳湖湿地DOM对铁还原菌异化还原水铁矿的影响
- Effect of DOM on dissimilatory reduction of ferrihydrite by iron reducing bacteria in Poyang Lake Wetland
- 基金项目：国家自然科学基金（No.41761095）
- 舒瑶
- 南昌大学资源环境与化工学院, 鄱阳湖环境与资源利用教育部重点实验室, 南昌 330031
- 弓晓峰
- 南昌大学资源环境与化工学院, 鄱阳湖环境与资源利用教育部重点实验室, 南昌 330031
- 李远航
- 南昌大学资源环境与化工学院, 鄱阳湖环境与资源利用教育部重点实验室, 南昌 330031
- 熊捷迁
- 南昌大学资源环境与化工学院, 鄱阳湖环境与资源利用教育部重点实验室, 南昌 330031
- 孙玉恒
- 南昌大学资源环境与化工学院, 鄱阳湖环境与资源利用教育部重点实验室, 南昌 330031
- 牛丹妮
- 南昌大学资源环境与化工学院, 鄱阳湖环境与资源利用教育部重点实验室, 南昌 330031
- 吴莉
- 南昌大学资源环境与化工学院, 鄱阳湖环境与资源利用教育部重点实验室, 南昌 330031
- 林媛
- 南昌大学资源环境与化工学院, 鄱阳湖环境与资源利用教育部重点实验室, 南昌 330031
- 摘要：湿地土壤和沉积物中的Fe（Ⅲ）还原过程是地球化学循环中重要的一部分，目前有关鄱阳湖湿地DOM的化学组成及其与Fe（Ⅲ）还原作用的构效关系尚不明确.为此，以鄱阳湖湿地沉积物中分离筛选出的铁还原菌作为模式菌，Fe（Ⅱ）的生成量作为考察指标进行Logistic方程拟合分析，并采用紫外-可见光谱、三维荧光光谱及XRD光谱，研究了不同浓度和来源的DOM对水铁矿的还原作用，并对"DOM-铁还原菌-水铁矿"体系中电子转移机制进行了探讨.结果表明，DOM对水铁矿的还原具有促进作用，当苔草DOM浓度为30 mg·L-1时，可使Fe（Ⅱ）含量增加39.7%；DOM对Fe（Ⅲ）还原的促进作用与水铁矿含量相关，在水铁矿添加量为0~1000 mg·L-1时，Fe（Ⅱ）含量显著增加，其中1000 mg·L-1下的Fe（Ⅱ）生成量是50 mg·L-1的13.2倍.不同浓度DOM对Fe（Ⅲ）还原的促进作用不同，表现为苔草DOM：150 mg·L-1>100 mg·L-1≈50 mg·L-1≈30 mg·L-1>20 mg·L-1>0 mg·L-1，沉积物和根际土DOM对Fe（Ⅲ）还原的促进作用均随着浓度（20、30、50 mg·L-1）的增加而略有增大.不同来源（苔草、沉积物、根际土） DOM对水铁矿还原的促进作用无显著性差异（p<0.05）.DOM对水铁矿还原的促进作用主要表现为低分子量组分（色氨酸、酪氨酸等）为铁还原菌提供营养物质和大分子量组分（腐殖酸、富里酸）作为电子穿梭物质.这些结果反映了DOM在电子转移反应中的重要性，为DOM的环境属性提出了一个新见解.
- Abstract：Fe(Ⅲ) reduction in wetland soils and sediments is an important part of the geochemical cycle. At present, the structure-activity relationship between DOM chemical composition and Fe(Ⅲ) reduction is still unclear. For this reason, the iron-reducing bacteria isolated from the sediments of Poyang Lake wetland were selected as the model bacteria, and the production of Fe(Ⅱ) was used as the investigation index for Logistic equation fitting analysis. The UV-Vis spectrophotometer, three-dimensional fluorescence spectrophotometer and XRD were used to study the reduction of ferrihydrite with different concentrations and sources of DOM, and the electron transfer mechanism in the "DOM-iron reducing bacteria-ferrihydrite" system was discussed. The results showed that DOM could promote the reduction of ferrihydrite. When the concentration of Carex DOM was 30 mg·L-1, the content of Fe (Ⅱ) increased by 39.7%. The promoting effect of DOM on Fe (Ⅲ) reduction was related to the content of ferrihydrite. The content of Fe (Ⅱ) increased significantly in the range of 0~1000 mg·L-1 of ferrihydrite, and the yield of Fe (Ⅱ) at 1000 mg·L-1 of ferrihydrite was 13.2 times higher than that at 50 mg·L-1. The promotion effect of DOM on Fe (Ⅲ) reduction was concentration dependent, and higher concentration of DOM has better performance. The promoting effect of sediment and rhizosphere soil DOM on Fe (Ⅲ) reduction increased slightly with the increase of concentration (20, 30, 50 mg·L-1). There was no significant difference in promoting effect of DOM from different sources (Carex, sediment and rhizosphere soil) on the reduction of ferrihydrite (p<0.05). Ferrihydrite reduction was mainly manifested that the low molecular weight components (such as tryptophan, tyrosine, etc.) provide nutrients for iron-reducing bacteria and the large molecular weight components (humic acid, fulvic acid) function as electron shuttle substances. These results reflect the importance of DOM in the electron transfer and provide a new insight into the environmental properties of DOM.
