氮同位素分馏机制、分析测试与示踪技术及其在生态环境中的应用

Nitrogen isotope fractionation mechanism,analysis measurement tracer technology and its application in ecological environment

【研究目的】氮(N)是地球陆地生态系统中的关键营养元素,也是引起水体富营养化的污染元素之一。随着分析测试技术的不断提高,氮稳定同位素技术已经发展成为一种常用的研究方法和分析手段,在氮的生物地球化学循环、水体富营养化和地下水污染来源识别等方面广泛应用。【研究方法】本文查阅近年来国内外生态环境领域氮稳定同位素的相关文献,综述了氮同位素分馏机制、氮同位素分析技术以及氮同位素在生态环境中应用的研究现状。【研究结果】(1)氮同位素质谱分析技术与氮同位素示踪技术目前已经建立了成熟体系。(2)硝化作用与反硝化作用是土壤氮转化循环的主要机制,生物固氮实现氮的输入,而植物或微生物产生含氮气体或矿化作用是氮输出的主要途径,并伴随着不同程度的氮同位素分馏效应。(3)氮同位素可以用来测定土壤氮素周转速率、N2O排放途径与生物固氮量、指示大气氮沉降变化、探究植物与土壤的相互作用及确定植物对氮素的吸收利用、识别农作物产地与水体、大气的氮污染来源。【结论】未来应将研究重点放在提升氮循环过程中不确定性来源的定量检测能力,确定未被发现的氮输入、积累和损失途径,完善并发展生态系统氮循环模型。

This paper is the result of environmental geological survey engineering.[Objective]Nitrogen(N)is a key nutrient across Earth's terrestrial ecosystems and one of the pollution elements that cause water eutrophication.Owing to the continuous improvements of analysis and testing techniques,nitrogen stable isotope technology has developed into a common research method and analysis mean,and has been widely used in nitrogen biogeochemical cycle,water eutrophication and groundwater pollution source identification.[Methods]In this paper,the relevant literatures on nitrogen stable isotope in the field of ecological environment domestic and overseas in recent years were reviewed,and the research status of nitrogen isotope fractionation mechanism,nitrogen stable isotope analysis technology and nitrogen isotope applications in ecological environment were summarized,the development of remediation technologys of nitrate pollution in groundwater were briefly described.[Results](1)A mature system of nitrogen isotope mass spectrometry and nitrogen isotope tracer technology has been established.(2)Nitrification and denitrification are the main mechanisms of soil nitrogen conversion cycle.Nitrogen input is realized by biological nitrogen fixation,and nitrogen output is mainly through nitrogen gas or ammoniation produced by plants or microorganisms,which is accompanied by different degrees of nitrogen isotope fractionation.(3)Nitrogen isotopes can be used to measure soil nitrogen turnover rates and N2O emission rates,improve biological nitrogen fixation,indicate changes in atmospheric nitrogen deposition,investigate the interaction between plant and soil and determine nitrogen uptake and utilization by plants,and identify crop area sources and pollution in groundwater and atmosphere.[Conclusions]Future researches should focus on improving the ability of quantitative detection of uncertainty sources in the nitrogen cycle,identifying undiscovered nitrogen input,accumulation and loss pathways,and perfecting and developing ecosystem nitrogen cycle model.