碳源对氮素在不同潜流带介质中的迁移转化规律研究

Study on the Effects of Carbon Sources on Nitrogen Migration in Different Mediums of Hyporheic Zones

通过室内土柱实验模拟氮素在不同沉积物的潜流带中迁移转化途径,选取粗砂、细砂、粉砂三种介质,以浓度为65.5mg/L的硝酸钾溶液为原水,研究硝态氮在不同沉积物的潜流带中的环境行为;再通过补充碳源,研究碳源对氮的迁移转化过程的影响。实验结果表明,在不同的沉积物介质中,氮的迁移转化不同,主要受介质孔隙度和介质中有机质的制约。由于粉砂介质中孔隙度较小,有利于微生物的附着,且有机质含量较多,反硝化作用和异化还原作用强烈,所以硝酸盐氮下降的最多,而在粗砂介质中孔隙度相对较大,不利于微生物附着,且有机质含量相对较低,反硝化作用和异化还原作用较弱,硝酸盐氮下降的较少。而添加碳源后,反硝化作用和异化还原作用增强,三根柱子中的硝酸盐氮都降到很低的值,说明碳源对潜流带中硝态氮的去除起着重要的作用。

We simulated the transportation and transformation of nitrogen in different mediums of hyporheic zones by the soil pillar experiment in laboratory.The experiment selects three media—the coarse sand,the fine sand soil and the silt soil.The concentration of potassium nitrate solution is 65.5mg/L in the raw water for studying the environmental behavior of nitrate in different mediums of hyporheic zones.After that,through the supplement of extra carbon source,we study on the effects of carbon sources on nitrogen migration.Experimental results demonstrate that the transportation and transformation of nitrogen is distinct in different mediums of hyporheic zones.Because it is restricted by the content of organic matter and the porosity of medias.The silt soil has minimum porosity,so it favors the attachment of microorganisms.The silt soil has high content of organic matter.The denitrification and the dissimilation-deoxidization of nitrate were strong relatively.As a result,the content of the nitrate is the lowest in the silt soil pillar.But the coarse sand has high porosity and it doesn＇t favor the attachment of microorganisms.Moreover the coarse sand has low content of organic matter.The denitrification and the dissimilation deoxidization were weak.The decrease of nitrate is minimum in the coarse sand pillar.After we supply extra carbon source,the denitrification and the dissimilation-deoxidization were enhanced.The content of nitrate is very low in the three pillars.It suggested that carbon source plays an important role in the removal of nitrate in the hyporheic zones.