Identification, fluxes and stable isotope composition of halocarbons released from halogen rich semi-arid environments

虽然最近已经确定陆地生态系统在挥发性卤代化合物的生产、消费和排放中发挥着重要作用，但它们的特征仍然很差。这些拟议的研究活动是环境保护和可持续发展研究中心研究单位HALOPROC的一部分，其目的是进一步探讨与环境有关的卤代烃的形成，如卤代甲烷、氯甲烷、溴甲烷、碘甲烷、三氯甲烷和溴仿；以及从富含卤素的土壤和相关植被中寻找以前没有特征的短期较大的卤素碳排放。最近开发的快速GC-MS系统将在实验室中使用在半干旱富盐环境中收集的样本(包括项目第一阶段和第二阶段的样本)来评估这些排放。此外，还将从这些土壤和植物样本中测量大量挥发性卤代化合物的稳定同位素值。将利用卤代碳的稳定碳和氢同位素组成(δ13C和δ2H值)来研究它们的生物地球化学循环和全球源-汇关系以及潜在的机制。将对影响卤代烃排放的几个环境参数进行基于实验室的调查。此外，将进行一系列复杂程度不同的实验室实验，以获得更多关于盐碱地和盐生植物中卤代碳形成的潜在机制的信息。在这些调查中使用的仪器还将与其他活动相联系，例如光化学/气雾室。

Although it has recently been established that terrestrial ecosystems play an important role in production, consumption and emission of volatile halogenated compounds, they are still very poorly characterized. The objective of these proposed research activities as part of the DFG research unit HALOPROC is to further explore the formation of environmentally-relevant halocarbons such as the halomethanes, chloromethane, bromomethane, iodomethane, chloroform and bromoform; and look for previously uncharacterized emissions of short-lived larger halocarbons from halogen rich soils and associated vegetation. A recently developed fast GC-MS system will be employed to assess these emissions in the laboratory using samples collected in semi-arid salt rich environments (including samples from the first and second phase of the project). In addition stable isotope values of abundant volatile halogenated compounds will be measured from these soil and plant samples. The stable carbon and hydrogen isotope composition (δ13C and δ2H values) of halocarbons will be used to investigate their biogeochemical cycles and global source-sink relationships, as well as the underlying mechanisms. Laboratory based investigations of several environmental parameters influencing the emissions of halocarbons will be conducted. Furthermore, a series of laboratory experiments with varying degrees of complexity will be conducted to gain more information about the underlying mechanisms involved in halocarbon formation in saline soils and halophytes. Instrumentation used in these investigation will also be linked into other activities such as the photochemical/aerosol chamber.