小叶碱蓬和白麻土壤—叶片生态化学计量学特征对不同盐生境的响应

[目的]分析干旱区盐生植物生境土壤与叶片生态化学计量特征在不同盐生境下变化趋势及主要限制因子,为研究干旱区盐生植物生长发育过程中养分限制因子和适应机制提供基础研究资料,同时为荒漠植物的生态保育和恢复提供参考。[方法]选取艾比湖湿地国家级自然保护区稀盐盐生植物小叶碱蓬(Suaeda microphylla)和拒盐盐生植物白麻(Apocynum pictum),测定其生境土壤pH值、含水量、盐分、速效磷、铵态氮、有机碳、全氮、全磷以及植物叶片有机碳、全氮、全磷,分析两种植物叶片与生境土壤生态化学计量特征的关系,探究植物叶片生态化学计量特征的土壤限制因子。[结果](1)随着盐分增加,两种植物生境土壤磷下降,有机碳、氮及化学计量比呈上升趋势,土壤养分含量受盐渍化程度影响显著;(2)两种植物叶片氮受土壤盐分影响显著,随盐分降低呈下降趋势,与土壤氮含量的变化趋势一致,叶片N/P平均值均小于14,表明研究区两种植物均受土壤氮含量限制;(3)RDA分析表明,影响小叶碱蓬叶片生态化学计量的主要因子为土壤pH值(p=0.034)、含水量(p=0.002),而白麻主要受土壤磷(p=0.002)、铵氮(p=0.048)影响。[结论]不同类型盐生植物在土壤—植物生态化学计量特征耦合关系上存在差异。稀盐盐生植物小叶碱蓬主要受土壤pH值、含水量的影响,拒盐盐生植物白麻主要受土壤磷、铵态氮含量影响。

Biotransformation of endosulfan by the tiger worm, <i>Eisenia fetida</i>

This study assesses the role of the earthworm, Eisenia fetida, in the breakdown of endosulfan in a soil environment. Two strains of E. fetida were used in this study to assess the effect of salinity on toxicity and metabolism of endosulfan in these earthworms. One strain of E. fetida (R) was reared in high salinity soil (over 2.0 dS/m of electric conductivity) from Shiwha lake, Korea. A control strain (W) was reared in pig manure compost. Acute toxicity of endosulfan was lower in the R strain when endosulfan was injected. In vitro metabolic studies of endosulfan based on microsomal preparations showed that both strains produced two major metabolites, endosulfan sulfate and endosulfan diol. The production rate of endodulfan sulfate was not significantly different between the strains, while endosulfan diol production was significantly different. In vivo metabolism studies showed only one primary metabolite, endosulfan sulfate, was produced by both strains. HPLC-MS/MS analysis showed annetocin was the indicative protein newly expressed in the R strain in relation to salinity exposure. These findings suggest salinity may induce hydrolyzing enzymes to produce endosulfan diol from endosulfan.