【作者】 滕应；

【导师】 黄昌勇；

【作者基本信息】 浙江大学 ， 土壤学， 2003， 博士

【摘要】 本项目选择红壤作为研究材料，采用室内培养、野外调查以及相关数学分析相结合的研究方法，探讨了重金属污染红壤的微生物生态特征及其影响机制，提出了镉、铅单一污染和镉、铅、铜、锌复合污染下红壤微生物学敏感性生态参数及其动力学变化特征，为重金属污染土壤的修复、环境质量评价以及建立有效的土壤重金属污染预警指标体系提供有益的参考。本项目研究所获得的主要结果如下： 1．以红黄泥和红砂泥两个土属作为供试红壤，采用室内培养方法对外加镉、铅污染红壤的微生物活性及群落结构进行了研究。结果表明：较低浓度Cd、Pb离子有利于提高土壤微生物活性，高浓度Cd、Pb离子则会对土壤微生物活性产生严重的抑制作用。当镉、铅的浓度分别大于15mg·kg^-1和200mg·kg^-1时两供试红壤的微生物活性开始下降。随重金属浓度增加，各指标下降幅度各有差别，其中微生物生物量碳、微生物生物量氮以及基础呼吸和微生物代谢商随重金属浓度增加而明显下降；土壤脱氢酶、脲酶、酸性磷酸酶活性的下降幅度较为明显，过氧化氢酶、蔗糖酶活性次之，蛋白酶活性较为稳定。几种生化作用强度的下降顺序为硝化作用＞固氮作用＞纤维素分解强度＞氨化作用；但土壤微生物生物量碳氮比则随着重金属污染水平的升高而增加。两种土壤比较，以上微生物活性指标对重金属胁迫的响应程度在红砂泥上表现更为明显。上述微生物活性指标与重金属间的相关性分析表明，微生物生物量碳、基础呼吸、微生物代谢商、脱氢酶活性与Cd、Pb的加入量呈极显著负相关性，土壤微生物生物量C∶N比与Cd、Pb的加入量呈现极显著正相关关系。可认为，微生物生物量碳、基础呼吸、微生物代谢商、脱氢酶活性及土壤微生物生物量C∶N比是敏感反映Cd、Pb污染状况的生物学指标。在本文中我们将供试红壤的上述微生物活性指标和2种重金属含量进行主成分因子分析，其结果得出，红黄泥和红砂泥的土壤微生物活性镉胁迫的临界承载量分别为15mg·kg¹和0～15·mg·kg¹；铅胁迫的临界承载量分别为200mg·kg^-1和200～400mg·kg^-1。这一结果将为重金属污染下红壤环境质量生物学评价提供参考。 镉、铅污染红壤微生物群落结构的研究结果亦表明，镉、铅严重污染破坏了土壤微生物区系，使土壤细菌、放线菌及真菌数量下降，其中放线菌对重金属毒性影响最为敏感，细菌次之，真菌受其毒性影响较少。BIOLOG GN测试结果显示，镉、铅污染红壤微生物群落代谢剖面（AWCD）及群落丰富度、多样性指数均显著低于非污染土壤，表明重金属污染引起了土壤微生物群落功能多样性下降，减少了能利用有关碳源底物的微生物数量、降低了微生 中义摘要物对单一碳源底物的利用能力，最终导致土壤微生物群落功能多样性发生变化。 2．通过对红黄泥和红砂泥两个红壤试样外加锻、铅的醋酸盐和氯化盐的培养试验，比较了锅、铅污染下相伴 OAC用7 CI阴离于对红壤微生物活性及其群落功能多样性的影响。研究结果表明：在相同重金属浓度卜，Cd、PbOAC“盐污染红壤的微生物生物量碳、基础ojT｛吸、代谢商、酶活性以及微生物数量、微生物群落代谢剖面和群落功能多样性的抑制作出入丁Cd、PbCI盐处理。进一步研究表明，锅、铅醋酸盐处理的十壤有效态里金属含量均明显高了氯化盐的处理。锅、出的醋酸盐利氯化盐的加入对红黄泥的pH值无明显影响，但对红砂泥的一值产生一定程度的影响。然而，从外加醋酸钾和氯化钾的另一辅助试验结果显示，在等量钾离于浓度条件下，川醋酸钾（KOAC）处理不仅没有对十壤微生物活性、数社及群落功能多样性产生抑制作用，反而有刺激作用，微生物生物量有～定幅度的增加，提高了微生物群落功能多样性。由此可认为，相伴 OAC和 CI阴离于的锅、铅盐导致污染红壤微生物生态特征指标差异并非相伴阴离于本身的直接影响，而主要是相伴阴离于影响重金属的生物有效性所致。并且，从培养前后测得的土壤pH的变化，可推测不同土壤其影响程度是不同的。3．在室内培养条件卜，应用四因素五水平二次止交问归旋转组合设计方案，对Cu、Zn、Ph。Cd复合污染红壤环境的微生物活性及群落功能多样性进行了研究。结果表明；至金属复合污染对红壤微生物活性及群落功能多样性的影响达显著或极显著性水平：而微生物生物量碳、十壤基础呼吸及群落功能多样性指数可较为敏感地反映红壤中重金属复合污染程度状况。同时，在复合污染试验条件下，＊d、CU对供试红壤各项微生物学指标的毒性影响较为明显，Zn次之，Ph的影响最小，并且在红砂泥中表现较为突出。因此，在该复合污染生境中重金属的微生物毒性效应发挥主要由Cd、Cll两元素决定，其生物毒性顺序表现为：Cd＞CU＞Zn＞Ph。与单一锅、单一铅污染处理相比，重金属复合污染对供试红壤微生物活性及其群落功能多样性的影响并非简单的加和作用，或协同作用或桔抗作用，而是一个非常复杂的复合作用。两元素交互效应进一步分析结果表明，当N＝400 ig·kg’、Cd－50 lgkg’，Zll＄400 n。gkg－’时，对红壤微生物学指标的影响 C更多还原

【Abstract】 In this paper, soil microbial ecological characteristics and their influence mechanism in red soils contaminated with heavy metals were studied using the incubation experiment, and field investigations. Some sensitive microbial ecological indexes and kinetic parameters were brought forward under the single pollution of cadmium or lead, and cadmium-lead-copper-zinc compound pollution ways, respectively, which will be useful reference for bioremediation, environmental quality evaluation and building up alert index systems in red soils polluted by heavy metals. Here the main results of this study are presented:1. Two incubation experiments were conducted to evaluate the effect of cadmium and lead applied singly on soil microbial activities and functional diversity of microbial community in red clayey soil and red sandy soil. The results showed the lower concentration of cadmium or lead helps to increase soil microbial activities, but their higher concentration cause greater inhibitory effect on microbial activities in red soils. Soil microbial biomass carbon, microbial biomass nitrogen, soil basal respiration and metabolic quotient all showed a decreasing trend under more than 15 mg.kg-1 cadmium or more than 200 mg.kg-1 lead, respectively. Soil dehydrogenase, urease and acid phosphotase activities have a significant decrease, and the activities of soil catalase and invertase taking sencond place, while soil protease activities showed stable state. The order of four soil biochemical intensity being sensitive to heavy metal pollution indicated as: nitrification>nitrogen fixation>decomposition of cellulose>ammonification. However, soil microbial biomass C:N ratio increased with the increasing of heavy metals level. Moreover, the effect of heavy metal pollution on soil microbial indexes was significant in red sandy soils. There were significant negative relationships among soil microbial carbon, microbial nitrogen, basal respiration, microbial metabolic quotient, urease activity, dehydrogenase activity, nitrification, nitrogen fixation and cadmium or lead concentration (R0.01=0.765, R0.05=0.632) .There was a close positive relationship between soil microbial biomass C:N ratios and cadmium or lead concentration (R=0.8920). Thus it can be seen that soil microbial biomass carbon, microbial biomass nitrogen, soil microbial biomass C:N ratio and microbial metabolism quotient are very sensitive to heavy metals pollution in red soils. Some soil microbial activity parameters and heavy metals contents were analyzed by principal component method. The results showed that the critical levels of cadmium and lead in red clayed soil and red sandy soil were 15 mg.kg-1 and 0-15.mg.kg-1, 200 mg.kg-1and 200-400 mg.kg-1, respectively.Soil microbial populations and functional diversities of microbial community have changed to some extent under the stress of cadmium and lead pollution. The number of soil bacterial, actinomycetes and fungus in red soils polluted by heavy metals decreased greatly compared with non-polluted soil samples. The order of sensitivity to heavy metals pollution was actinomycetes > bacteria > fungus. At the same time, the result of the functional diversity of soil microbial community indicated that soil microbial metabolism quotient (AWCD), microbial community richness and shannon index all decreased significantly in red soils polluted by cadmium and lead compared with non-polluted soils. These results suggested the structure of microbial community have changed, decreased the functional diversity of microbial community, and reduced the microbial number utilizing different carbon resources.In a word, the changing of soil microbial activities and the functional diversity of microbial community reflected to some degree the evolvement law of environmental ecological function of soil contaminated with heavy metals. Simultaneously, some soil microbial parameters were very sensitive to cadmium and lead pollution.2. Two laboratory incubation experiments were carried out to evaluate the influence of accompanyin更多还原