石家庄污灌区水土环境中铁氧化菌及其影响因素分析

为了查明河北省石家庄市近郊污灌区包气带和地下水的污染状况,采用最大可能数法(MPN法)对污灌区水土环境中的常见细菌进行培养,通过铁氧化菌在水土环境中数量的变化及其与各环境因子之间的关系分析得出:研究区铁氧化菌在pH为7.4(中偏碱性)、氧化还原电位(ORP)为318 mV(氧化环境)、温度为15℃、溶解氧(DO)质量浓度为4.7~7.8 mg/l、井深40 m的地下水环境中生长较好,数量可达1.1×105个/ml;铁氧化菌在pH为8.07~8.28、含水量为19.0%~22.9%、岩性为粉土、深度为3.5 m以浅的土壤环境中生长较好,数量可达5.1×107个/g。研究结果表明由于长期污灌,研究区的浅层地下水和上部3.5 m的土壤不同程度地受到污染。铁氧化菌在水土环境中大量繁殖,并不断地把可利用的Fe2+氧化成不溶性的Fe3+,影响了研究区的水土环境,使研究区的生态环境产生变化。

Analysis on Iron-oxidizing Bacteria and Their Influencing Factors in Waterand Soil Environment of Sewage Irrigation Area in Shijiazhuang

In order to identify the sewage irrigation pollution of unsaturated zone and groundwater in the suburb of Shijiazhuang City,common bacteria in the soil and water of sewage irrigation area were cultivated through maximum probable number method(MPN method).Iron-oxidizing bacteria were cultured and analyzed by the change of the number of iron-oxidizing bacteria in the soil and water and its relationship between environmental factors,this paper indicates that the best aqueous environment for the growth of iron-oxidizing bacteria in the study area is pH=7.4,showing in the alkaline and neutrality condition,ORP=318 mV,meaning in an oxidation environment,temperature=15 ℃,DO=4.7-7.8 mg/l and depth=40 m,and the amount of bacteria is up to 1.1 × 105 cells/ml;the best soil environment is that pH is 8.07-8.28,water content is 19.0%-22.9%,lithology is silt,depth is less than 3.5 m,and the amount of bacteria is up to 5.1 × 107 cells/g.The result shows that the shallow groundwater and the surface soil(depth<3.5 m)in the study area are polluted at different degrees because of long-term sewage irrigation.Iron-oxidizing bacteria quickly rear in soil and water environment,and constantly oxidize water-soluble Fe2+ into water-insoluble Fe3+,this process affects the water and soil environment of the study area,then changes the ecological environment of the study area.