摘要
稳定同位素技术是揭示食物网中物质的循环路径和探究消费者、生产者间的营养关系的重要方法.但是,不同的样品处理方法可能引起同位素比值的变动,使得食物网模型的建立和各研究结果间的相互比较存在一定的困难.样品的预处理主要分为四个环节,即保存、分离、酸化和干燥.在水域生态系统中,水体中的颗粒,溶解性有机物质、细菌、浮游动物、藻类、水生植物、鱼类及底栖动物等采集后,通过分离纯化,得到目的样品,-20℃冷冻保存.对于含有无机碳酸盐的生物样品,例如沉积物、含有钙质结构的无脊椎生物、部分浮游生物等需要酸化处理以排除无机碳对6"c测定的影响,1mol/L.HCl滴加可以达到很好的去除效果.对于生物样品δ15N的测定则不需要酸化处理.最后,样品经冷冻干燥或40—70℃低温烘干以备稳定同位素的测定.另外,用福尔马林、乙醇等保存在博物馆里的样品,对于长时间尺度上食物网的重建具有重要的生态学意义.本文系统总结了不同研究中样品处理过程的差异,分析其干扰机制,为进一步的方法学研究奠定了基础.
Stable isotope analysis is commonly used in studying flows of mass and energy through food webs and trophic relationships in aquatic ecosystems. However, different sample processing methods can influence the measurement of these stable isotope rates, which may result in errors in the resulting food web models and the comparing results between different studies. In particular, errors may result from four different sources, that is, preservation, separation, acidification and dehydration. The collectted particulate/dissolved organic matter, bacteria, zooplankton, algae, hydrophyte, fish and zoobenthos were rinsed with de-ionized water to clean off epibionts, and then stored at -20℃. Acidification by adding lmol/L HCI drop-by-drop was needed for carbon isotope analysis in samples of sediment organic matter, invertebrates with calcareous structures, and plankton. For nitrogen analysis, acidification should be avoided. Finally, dehydration was required by the analytical methods used in the determination of isotopic abundance. Both freeze-drying and drying at 40-70℃ were acceptable. In addition, materials preserved with formalin and ethanol stocks was suitable for current ecological applications of isotopic analysis and open up the possibility to reconstruct food webs and biogeochemical changes at scales of tens or hundreds of years. In this review we summarize different sample processing prior to the analytical determination of stable isotope ratios and the influence mechanism of some processing methods, which are fundamental for further methodology research.
出处
《湖泊科学》
CAS
CSCD
北大核心
2008年第1期13-20,共8页
Journal of Lake Sciences
基金
国家重点基础研究发展计划(973)项目(2002CB412305)
国家自然科学基金项目(40471045)
中国科学院百人计划联合资助．
