河口潮滩湿地沉积物中胞外酶研究

【作者】 刘存歧；

【导师】 陆健健；

【作者基本信息】 华东师范大学 ， 生态学， 2003， 博士

【摘要】 本文以长江口典型湿地—崇明东滩为例，首次研究了沿高程梯度或沿植被演替系列沉积物中碱性磷酸酶等五种胞外酶活性的空间分布规律，分析了胞外酶活性与环境因子的相互关系及其产生机制，讨论了胞外酶活性在湿地植被演替中的作用。同时以崇明东滩沉积物为对象，运用重金属离子的添加和去除等方法，研究了重金属离子对沉积物中碱性磷酸酶活性的影响，利用胞外酶活性的变化探讨了崇明东滩重金属污染的状况。此外，本文还研究了横沙东滩吹泥试验工程对沉积物环境因子和胞外酶活性的影响并进行了对比分析。上述工作的开展不仅有助于丰富湿地沉积物胞外酶的理论，理解湿地生态系统的生态过程，而且对于河口湿地的保护和利用具有重要的现实意义和应用价值。 主要研究结果如下： 1．崇明东滩沉积物中胞外酶活性沿高程梯度或演替系列呈规律性变化，沉积物理化性质影响着胞外酶活性的分布。 崇明东滩沉积物中沿高程梯度碱性磷酸酶活性有增加的趋势。而各植被样带沉积物中碱性磷酸酶活性、Vmax除在表层有一高值以外，各植被样带在20-30cm处有一较高峰值，而Km值在该处有一较低值，说明除了表层之外，在亚表层有一个令人注意的碱性磷酸酶活跃区。通过直线回归分析发现，碱性磷酸酶活性与沉积物中粒径、溶解无机磷含量呈显著负相关，与总磷、有机质、总氮含量呈显著正相关。最大反应速度Vmax与环境因子的关系与有机质、总氮呈正相关，而Km则相反。说明有机质总氮含量是提高碱性磷酸酶活性的重要因素，同时反映出碱性磷酸酶活性受底物和产物并存机制的诱导或抑制，这种并存机制在其它土壤或沉积物碱性磷酸酶的研究中并不多见。华东师范大学博士学位论文摘要 过氧化氢酶活性随着演替的发展有逐渐增大的趋势。各植被带酶活性垂直分布受环境因子的影响而没有统一的分布规律。无论是水平还是垂直样品，沉积物过氧化氢酶活性与有机质、总氮、总磷呈正相关，与溶解无机磷和沉积物粒径呈负相关。充分反映了随着演替的发展，沉积物的肥力逐渐增高的特点，也反映了沿高程梯度沉积物生物氧化作用逐渐增强。 蛋白酶活性从光滩到芦苇带有降低的趋势，各植被样带垂直样品蛋白酶活性低于表层。与环境因子分析表明，蛋白酶活性与有机质、总氮呈负相关，而与溶解无机磷和沉积物粒径呈正相关。从光滩到芦苇带，硅藻数量逐渐降低，导致沉积物中蛋白质含量降低，影响着蛋白酶的活性，也可能说明蛋白酶主要来源于藻类，因此蛋白酶活性的高低更决定于有机质的类型而与有机质总量无关。 转化酶活性从光滩到芦苇带变化并不明显，在海三棱蔗草带略高。垂直分布在10一3Ocm处有较高的值。与环境因子无显著的相关关系。转化酶活性的大小与分布可能与有机物组成有关。 崇明东滩沉积物中脉酶活性很低，甚至难以检出，与各环境因子无显著相关关系。 2.向沉积物中添加金属离子实验发现，重金属离子对崇明东滩沉积物中碱性磷酸酶的作用方式有两种:Hg、Cd、Pb、Cu等离子对碱性磷酸酶有抑制作用，通过生态剂量分析，四种金属离子对碱性磷酸酶的抑制作用强弱存在差异，顺序为HgZ，>Cu卜)Pb2+>CdZ‘;Zn和Mn离子在低浓度下激活碱性磷酸酶的活性，而在高浓度下则起抑制作用，说明崇明东滩Zn和Mn的污染性不大。通过向不同植被带沉积物样品中添加鳌合剂EDTA以消除重金属离子，发现在各样带沉积物碱性磷酸酶活性最高时相对应的EDTA添加量不同，海三棱蔗草带低于混合带和芦苇带，与各样带重金属的累积含量相一致，EDTA的添加量能够综合反映潮滩湿地重金属的污染程度，由于对酶起作用的重金属形态为华东师范大学博士学位论文摘要离子态，因此利用胞外酶活性来评价沉积物重金属的污染状况更具实践意义。 3.横沙东滩沉积物中存在Cd、Sn、Pb等重金属元素为主的污染，吹泥后沉积物粒径减小，总磷含量明显增加，重金属污染有增加的趋势。尤其是SN，，站位最为明显，这与SN，，站位处于深槽，积累了大量的吹泥原土有关。吹泥后碱性磷酸酶活性显著低于吹泥前，原因在于重金属尤其是Zn的抑制作用。而过氧化氢酶在重金属含量较高的站位具有较高的酶活性，说明了微生物应激反应的存在，过氧化氢酶活性能反映出水域沉积物中污染的程度。转化酶、蛋白酶、脉酶活性无显著变化。因此，碱性磷酸酶和过氧化氢酶活性对环境变化有较好的指示作用。以上说明吹泥对横沙东滩底质环境造成较大的影响，长期影响需进一步跟踪研究。 总之，潮滩湿地高程和沉积物粒径影响着物质的积累和群落的演替，从而决定着胞外酶活性的变化。胞外酶对环境因素的变化具有敏感性，决定了其活性可以作为环境变化的评价指标。更多还原

【Abstract】 The paper studied three aspects of extracelluar enzymes in sediments of the tidal flat wetland, namely 1) the distibution of five sorts of extracellular enzymes in sediments in the East End of Chongming Island along the elevation gradient or community succession series, the relationships between the activities of enzymes and the ecological factors, and functions of extracellular enzymes in the process of community succession; 2) the effects of the heavy metal ions and EDTA on the activity of alkaline phosphatase in sediments of the East End of Chongming Island by adding and removing of heavy metal ions, discussing whether the activities of extracellular enzymes could be taken as the indicators for the environmental status; 3) the variations of the activities of extracellular enzymes in sediments in the East End of Hengsha Island after the discarding clay. These studies would enrich the knowledge of the extracellular enzymes, help us to understud the ecological processes of wetland ecosystem and be important practice to direct the conservation and development of the estuarine tidal flat wetlands.The major conclusions drew on this studies are:1 . The activities of extracellular enzymes in sediment in the east end of Chongming island changed regularly along the elevation gradient, the physical and chemical factors affected the activities of extracellular enzymes.Along the elevation gradient or succession series, the activity of alkaline phosphatase increased gradually. Besides the surface sediments* alkaline phosphatase of sediments in every vegetation area has higher peak activity and Vmax,but a lower Km at the depth of 20-30cm.lt was proved that there was a remarkably active zone of the alkaline phosphatase in the sediments besides the surface layer. The activity of alkaline phosphatase was significantly correlated to the particle size and dissolved inorganic phosphorus negatively but opposite to organic matters and total nitrogen. Vmax had a same trend as activity of alkaline phosphatase, but opposite to Km. Theresults suggested that organic matter and total nitrogen could increase the activity of alkaline phosphatase, and that the activity of alkaline phosphatase was activated or inhibited by substrate and product due to co-existence. This mechanism was reported poorly in the wetland sediments or soils.With succession of community, the activity of catalase increased gradually, and the vertical variation of the activity was affected by environmental factors and didn’t show identical rule. No matter what kinds of sample, including the horizontal and vertical, the activity of catalase was correlated to organic matter, total nitrogen and total phosphorus positively, but opposite to dissolved inorganic phosphorus and particle size of sediments. It suggested that the fertility of sediment and biological oxidation was improved with succession.The activity of proteinase decreased from bare flat to reed zone, and the activity in deeper sediment was lower than surface sediment. The activity of proteinase was correlated to organic matters and total nitrogen negatively, but opposite to dissolved inorganic phosphorus. From bare flat to reed zone, theconcentration of protein declined with diatom quantity which influenced the activity of proteinase. It suggested that proteinase in the sediments was probably produced by diatom, and the activity of proteinase was decided by the types of organic matter but not the concentration of organic matter.From bare flat to reed zone, the activity of sucrase changed insignificantly. There was a higher activity in triangle sulbush(5c/rp? mariquetef) zone than other vegetation zones. To the vertical distribution, there was higher activity at 10-3 Ocm depth. The activity of sucrase had insignificant correlation to the environmental factors. It may mainly depend on the composition of organic matter more than the organic matter.The activity of urease is too low to detect nearly and it had no correlation with environmental factors.2. The experiment of heavy m更多还原