紫色母岩作基质或覆盖材料对景观水体氮磷去除效果研究

Effect of Using Purple Parent Rock as Substrate or Cover Material on Removal of Nitrogen and Phosphorus in Landscape Water

选取重庆地区分布面积较广的蓬莱镇组、飞仙关组和遂宁组3种不同紫色母岩,研究其作基质或覆盖材料对富营养化景观水体氮磷去除及微生物群落结构的影响。结果表明,利用3种紫色母岩作基质时对水体总氮(TN)、总磷(TP)的去除效果差异较大,蓬莱镇组的去除效果最好;利用3种母岩作覆盖材料时3种母岩均可显著抑制底泥TN、TP的释放,且处理间无显著差异。等温吸附试验表明,3种母岩对TN的吸附均为单层分子吸附和表面吸附,对TP的吸附主要为单层分子吸附,其中,蓬莱镇组母岩的物理吸附能力较强,对TN、TP的最大理论吸附量分别为0.259、0.619 mg·g^(-1)。3种母岩作基质或覆盖材料处理后均会不同程度地改变系统中微生物的群落结构,且不同母岩在水体中释放出的微量元素含量不同,其中,蓬莱镇组紫色母岩向水体中释放的钙(Ca)、钾(K)、铜(Cu)、锰(Mn)、钼(Mo)元素均显著高于飞仙关组和遂宁组紫色母岩。综上,无论作基质还是覆盖材料,蓬莱镇组母岩对氮磷的治理效果均较好,这主要是由于其对水体氮磷的物理吸附作用强于另外2种母岩。此外,3种紫色母岩作基质或覆盖材料时会向系统中释放微量元素,从而影响系统微生物群落结构,进而影响景观水体氮磷的治理效果。

【Objective】The subject of how to construct landscape water bodies for reshaping living environment is getting increasingly popular among scholars.However,most landscape water bodies are closed or semi-closed catchments and easy to get polluted by external pollutants from agricultural wastewater,ornamental fish excretion,and atmospheric sedimentation and eventually eutrophied.Often in those eutrophied landscape water bodies harmful algal blooms,fish kills,and many other related problems occur.The primary cause of landscape water eutrophication is the excess of N and P in the water body.Thus,reduction of N and P in the water body is the key to control of landscape water eutrophication.【Method】Samples of three kinds of purple parent rocks(Peng-lai-zhen Formation(J3p),Fei-xian-guan Formation(T1f),and Sui-ning Formation(J3s)),which are widely distributed in Chongqing,were collected and used as substrate or super stratum in a simulation experiment to explore effects of the purple parent rocks on landscape water purification.Isothermal adsorption tests were conducted to determine physical adsorption abilities of the purple parent rocks,separately.Microbial community structure of each treatment system was analyzed with phospholipid fatty acid(PLFA).【Result】The following findings were obtained.The three kinds of purple parent rocks,when used as substrate,varied in total nitrogen(TN)and total phosphorus(TP)removing efficiency,with J3p in the lead.However,when used as substratum,they effectively inhibited sediments from releasing TN and TP but to a similar extent.The isothermal adsorption tests show that TN adsorptions on the three kinds of purple parent rocks were all in the form of monolayer adsorption and surface adsorption,and TP adsorptions mainly in the monolayer adsorption.Among them,J3p was the highest in physical adsorption capacity and its maximum theoretical adsorption capacity of TN and TP reached 0.259 mg·g-1 and 0.619 mg·g-1,respectively.The use of the purple parent rocks as either substrate or cover material altered the microbial community structures of their respective treatment systems.Compared with CK,T1f and J3s as substrate promoted significantly growth of the bacteria,fungi and protozoa in the landscape water,while J3p did little the growth of water microorganisms.Used as cover material,all the purple parent rocks promoted markedly growth of the bacteria in the water and sediment,but varied in the effect on fungi in the water and sediment.At the same time,number of the bacteria(labeled as PLFA18:0)in the matrix treatment system was significantly and positively related to the content of total nitrogen in the overlying water,while numbers of the bacteria(labeled as PLFA16:0)in the overlay treatment system was significantly and negatively related to the content of total phosphorus in the overlying water.Moreover,the rocks also varied in release of trace elements.J3p released more Ca,K,Cu,Mn and Mo than T1f and J3s did【Conclusion】All the findings demonstrate that application of Peng-lai-zhen Formation purple parent rock as substrate or barrier material could effectively control both nitrogen and phosphorus pollutions in landscape water,which is attributed to its high physical adsorption capacity.Furthermore,releasing of trace element from purple parent rock during the treatment process could alter microbial community structure of the system,and hence affect removal of TN and TP from the system.