基于野外数据建立大型底栖动物电导率水质基准的可行性探讨

科学合理地设定水质基准是水生生物保护和水生态系统恢复的基础。水体电导率数值的高低由溶解于其中的各种阴阳离子的浓度所决定,而较多的研究也证明电导率能够显著地影响水生生物类群,特别是大型底栖动物物种存活和群落结构的稳定性。离子组成的复杂性,导致无法开展基于室内实验的水生生物电导率基准值的推导。本文借鉴美国环境保护局基于野外调查数据建立电导率基准值的方法,采用流行病学打分方法,分别从电导率是否对大型底栖动物敏感物种存在毒性效应、人为干扰的增强是否会通过电导率产生毒性作用,以及其他环境因子是否对电导率基准值的制定产生影响3个方面,探讨了基于野外数据建立我国电导率基准的可行性。研究区域为辽河流域的浑河及太子河,野外调查数据采集于2009年8月至2010年5月。研究结果表明,电导率的升高显著降低了大型底栖动物敏感物种的出现频率。通过分析研究区域土地利用方式同电导率之间的相关性,证明了农业和城镇建设用地比例的增加显著地增加了水体中电导率的数值。对有可能引起物种消失的其他环境因子进行分析,结果表明电导率是引起大型底栖动物消失的主要原因。综合以上结果,基于野外调查数据来建立大型底栖动物电导率基准值是可行的,为我国水质基准的研究提供了新的思路和方法。

Exploring the Feasibility of Establishing Conductivity Criteria for Macroinvertebrate Based on the Field Investigations

Establishing the criteria of water quality is the basis for protecting aquatic organisms and ecosystem. The level of conductivity is determined by the concentration of ions dissolved in the water. Several studies have shown that conductivity affects the survival of aquatic organisms and stability of macroinvertebrate community. Due to the complexity of composition of dissolved icon, it is difficult to establish the conductivity criteria for aquatic organisms on the basis of experimental data. In the present work, we used the methods from US EPA to establish the conductivity criteria based on the field data. Moreover, we utilized epidemiology scoring method to explore the feasibility whether setting the relevant conductivity criteria is feasible in China. Three research contents were conducted to test the feasibility, including (1) Are macroinvertebrate sensitive species affected strongly by conductivity, (2) Does the anthropogenic disturbance impose toxicity effect on aquatic ecosystem through conductivity and (3) Do some other environmental factors affect the accuracy of setting the criteria? The study area is located in northeast China which consists of two different rivers, namely Hun River and Taizi River. The field data were collected during August 2009 to May 2010. The results showed that conductivity decreased the occurrence frequency of sensitive species significantly. The ratio of agriculture and urban land use increased the conductivity level by analyzing the correlation between landuse and conductivity. Conductivity was the main reason for dying out of sensitive species by analyzing the effects of other environmental factors which may cause the same influence. In summary, establishing conductivity criteria based on field data is feasible, and moreover, some new ideas and methods should be applied for the future studies in relation to the water criteria.