外源性重金属铅和镉对河流底泥微生物酶活和有机质降解的影响研究

发布时间：2018-02-11 07:24

本文关键词： 外源性污染铅镉酶有机质　出处：《湖南大学》2015年硕士论文　论文类型：学位论文

【摘要】：随着工业化、城市化进程的加快,大量的工业废水、废渣、生活污水被排放到河流中,使得河流底泥中重金属污染日益严重,并对人类的生活健康产生一定的危害。重金属铅和镉是河流底泥中常见的两种重金属污染物。本文选择河流底泥微生物酶活和有机质降解率为研究对象,在不同浓度外源性铅和镉污染培养条件下,通过监测底泥中脲酶活性、过氧化氢酶活性、蛋白酶活性、有机质含量、离子态铅含量、离子态镉含量、EDTA态铅含量和EDTA态镉含量的变化,分析了底泥微生物酶活对外源性重金属污染的响应机制,以及外源性重金属污染对有机质降解率的影响。实验结果表明,外源性重金属浓度和污染时间是影响生物酶活性和有机质降解的重要因素,且这两个因素之间的交互作用对生物酶活性有显著的影响。实验初期,中低浓度的外源性铅对脲酶有促进作用,中高浓度的镉对脲酶有抑制作用,受外源性铅和镉污染的底泥中过氧化氢酶活性和蛋白酶活性受到抑制；实验中期和后期,低浓度的外源性重金属污染对底泥中脲酶、过氧化氢酶和蛋白酶有促进作用；实验后期,受抑制的生物酶酶活性有所恢复,但是高浓度重金属污染条件下,生物酶活性仍受到抑制。底泥中离子态铅和镉的含量先上升后下降,底泥中EDTA态铅和镉的含量随着时间的变化而上升。皮尔森相关分析显示,脲酶活性变化和离子态或EDTA态铅和镉的含量负相关性,过氧化氢酶活性和EDTA态铅含量之间在第3天、第10天和第30天存在极显著的负相关性,过氧化氢酶和蛋白酶与离子态镉和EDTA态镉含量存在显著的负相关性,蛋白酶活性变化和EDTA态铅含量之间的相关性不显著。有机质的含量随着时间的变化逐渐减少,受重金属污染的底泥中有机质含量比未受重金属污染的底泥中含量要低,不同浓度外源性铅和镉污染条件下有机质降解率存在显著性差异,有机质含量和外源性重金属铅污染下的底泥脲酶活性在第45天有显著的正相关性,与过氧化氢酶活性在第30天有显著地正相关性,与蛋白酶活性存在负相关性。有机质含量和外源性重金属镉污染下的底泥脲酶活性在第7天、第15天和45天有显著的正相关性,与过氧化氢酶活性在第45天有显著地正相关性,与蛋白酶活性在第7和第30天存在显著地正相关性。研究发现的结果将有利于提高对底泥生态毒理机制的认识。
[Abstract]:With the acceleration of industrialization and urbanization, a large number of industrial wastewater, waste residue and domestic sewage are discharged into the river, which makes the heavy metal pollution in the river sediment more and more serious. Heavy metal lead and cadmium are two common heavy metal pollutants in river sediment. In this paper, microbial enzyme activity and degradation rate of organic matter in river sediment are selected as the research objects. Urease activity, catalase activity, protease activity, organic matter content, ionic lead content in sediment were monitored under different concentrations of exogenous lead and cadmium contamination. The changes of ionic cadmium content, EDTA lead content and EDTA cadmium content were analyzed. The response mechanism of microbial enzyme activity to exogenous heavy metal pollution and the effect of exogenous heavy metal pollution on the degradation rate of organic matter were analyzed. The concentration of exogenous heavy metals and the time of pollution are the important factors that affect the bioenzyme activity and the degradation of organic matter, and the interaction between these two factors has a significant effect on the bioenzyme activity. The activity of catalase and protease in the sediment contaminated by exogenous lead and cadmium was inhibited, and the activity of catalase and protease was inhibited in the middle and late stages of the experiment, and the activity of catalase was inhibited in the sediment contaminated by exogenous lead and cadmium, and the activity of catalase and protease was inhibited in the middle and late stages of the experiment. The low concentration of exogenous heavy metals can promote urease, catalase and protease in sediment, but in the late stage of experiment, the inhibited enzyme activity of biological enzyme recovered, but under the condition of high concentration of heavy metal, the enzyme activity of urease, catalase and protease in sediment was improved. The contents of ionic lead and cadmium in sediment increased first and then decreased, and the contents of lead and cadmium in EDTA increased with time. Pearson correlation analysis showed that. The changes of urease activity were negatively correlated with the contents of lead and cadmium in ionic or EDTA forms, and the activities of catalase and lead in EDTA were significantly negative correlated on the 3rd, 10th and 30th day, respectively. There was a significant negative correlation between catalase and protease and the contents of ionic cadmium and EDTA cadmium, but there was no significant correlation between the changes of protease activity and the content of lead in EDTA, but the content of organic matter decreased gradually with the change of time. The content of organic matter in sediment polluted by heavy metal was lower than that in sediment without heavy metal pollution. There was significant difference in degradation rate of organic matter under different concentrations of exogenous lead and cadmium. There was a significant positive correlation between organic matter content and urease activity in sediment contaminated by heavy metal lead on the 45th day and the catalase activity on the 30th day. The content of organic matter and urease activity of sediment contaminated by exogenous heavy metal cadmium were positively correlated on the 7th, 15th and 45th day, and positively correlated with the catalase activity on the 45th day. There was a significant positive correlation between protease activity and protease activity on the 7th and 30th days. The results of the study will help to improve the understanding of the mechanism of sediment ecotoxicology.
【学位授予单位】：湖南大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X522;X172

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