异化铁还原对水稻土CH_4,CO_2及N_2O形成的抑制

Effect of iron oxide addition on inhibition of CH_4,CO_2 and N_2O in anaerobic paddy soil

采用厌氧泥浆恒温培养实验,测定了4种不同水稻土及添加外源氧化铁后土壤中CH4,N2O和CO2分压及Fe()浓度的变化,探讨了影响温室气体产生的土壤化学及生物学因素。结果表明:不同土壤中甲烷产生量有很大差异,其产甲烷能力的顺序表现为四川水稻土>江西水稻土>吉林水稻土>广东水稻土,添加氧化铁可显著抑制土壤中甲烷的形成。培养过程中不同土壤产生的CO2浓度相近,变化趋势也基本相同,添加氧化铁后均可导致CO2浓度显著降低。广东水稻土中N2O气体分压显著大于其他土壤,并且释放高峰期持续时间长,不同水稻土N2O产生能力的顺序为广东水稻土>四川水稻土>江西水稻土>吉林水稻土。添加Fe(OH)3后,江西、四川和吉林水稻土中N2O气体分压明显降低,而广东水稻土表现为释放高峰期推后。吉林、四川和江西水稻土中铁还原比较迅速,而广东水稻土中铁还原有明显滞后现象。添加乙酸盐和H2对广东水稻土中甲烷生成有明显的促进作用,证实了乙酸盐及H2浓度是限制广东水稻土甲烷生成的重要条件,添加氧化铁可有效抑制外源乙酸盐及H2的产甲烷过程。

The variation of the partial pressure of CH4,N2O,CO2 and the concentrations of Fe （ Ⅱ ） were determinated under anaerobic incubation and after adding iron oxide by slurry experiment of four different paddy soils. The factors of soil chemistry and biology that influence the greenhouse gas production were discussed. The obtained result showed that ：Methane production in four paddy soils was different. The sequence of methanogenesis ability was Sichuan paddy〉Jiangxi paddy〉Jilin paddy〉Guangdong paddy. Adding iron oxide to those paddies could inhibit the quantity of production of methane and reduce the concentration of CO2 ,and the concentrations of CO2 under anaerobic incubation were closer,the variety was also similar. The partial pressure of N2O in Guangdong paddy was higher than that in other paddies and in Guangdong paddy the duration of the peak of partial pressure of N2O was longer than others. The sequence of N2O-produced ability was Guangdong paddy〉Sichuan paddy〉Jiangxi paddy〉Jilin paddy. After adding Fe（OH）3,the partial pressures of N2O in Jiangxi paddy,Sichuan paddy and Jilin paddy were remarkably reduced,but there was a peak hysteresis in Guangdong paddy. The process of iron reduction was more rapid in Jiangxi paddy,Sichuan paddy and Jilin paddy than that in Guangdong paddy. Adding acetate and H2 to paddy can increase the production of methane in Guangdong paddy. The result showed that the concentration of acetate and H2 were factors limiting methanogenesis in Guangdong paddy. Adding iron oxide to paddy may effectively inhibit methanogenesis by additive acetate and H2.