中文摘要：

为探讨光照和硫酸盐对微生物Fe（Ⅲ）还原的影响,在光照和光暗转换条件下,采用厌氧泥浆恒温培育方法分别在四川和天津2种石灰性水稻土中添加不同浓度硫酸盐溶液（20、50、800mmol·kg-1）,培养过程中定期测定土壤泥浆的Fe（Ⅱ）、叶绿素a含量和pH值。结果表明：光照条件下,添加20mmol·kg-1和50mmol·kg-1硫酸盐能减缓光照培养中因为蓝细菌光合作用放氧引起的Fe（Ⅱ）氧化反应,Fe（Ⅱ）氧化反应启动时间与对照处理相比延迟3～7d;蓝细菌在光照培养5d后开始迅速繁殖生长,叶绿素a增长速率表现为随硫酸盐浓度增大而增加,其最终含量在四川和天津水稻土中分别为20mg·kg-1和16mg·kg-1;800mmol·kg-1硫酸盐则完全抑制了Fe（Ⅱ）的重新氧化,且在整个培养周期中没有发现光合细菌存在。pH值变化呈现先微弱下降后升高的趋势,但始终维持在弱碱性范围内。当由光照转入避光培养后,Fe（Ⅱ）累积量又重新回升,增长速率表现为对照〉20mmol·kg-1S处理〉50mmol·kg-1S处理。表明光照并非直接影响铁还原微生物,而是通过光合微生物繁殖间接影响铁还原过程。

英文摘要：

The objective of this study is to investigate influences of sulfate and illumination on microbial iron（Ⅲ） reduction.The calcareous paddy soil samples were separately collected in fields from Tianjin municipality（TJ） and Sichuan province（SC） of China.The sulfate solutions with three concentrations levels（20,50,800 mmol·kg-1） were added into air-dried soils in laboratory to simulate natural flooding process.The method of slurry anaerobic incubation at 30 ℃ was adopted under two illumination conditions,one was simulated natural illumination,and the other one was that simulated natural illumination was kept in the early 35 days and then changed to dark.The contents of Fe（Ⅱ）,chlorophyll a（Chl a） and pH were determined termly.Results showed that,the sulfate solutions amended at 20 mmol·kg-1 and 50 mmol·kg-1 could mitigate Fe（Ⅱ） oxidation resulted by O2 from cyanobacteria under illumination,and the starting time of Fe（Ⅱ） oxidation was delayed for 3~7 d compared with the control.cyanobacteria had a rapid growth after incubation of 5 days,and content of Chl a increased with sulfate concentration increased,and the final content were 20 mg·kg-1 and 16 mg·kg-1 in SC and TJ paddy soils,respectively.The sulfate solution at 800 mmol·kg-1 completely inhibited Fe（Ⅱ） re-oxidation and photosynthetic bacteria did not occur.The pH of slurry maintained in the range of weak alkaline.In the case of the dark incubation stage,the Fe（Ⅱ） accumulation increased with the order control20 mmol·kg-150 mmol ·kg-1.In conclusion,light did not affect iron-reducing bacteria;iron reduction was indirectly affected by photosynthetic bacteria.