Ecohydrological Controls on Carbon Drainage Fluxes in Natural and Human-Impacted Watersheds

自然和人类影响流域碳排放通量的生态水文控制

• 批准号: RGPIN-2014-05065
• 负责人: Johnson, Mark
• 金额: $ 2.7万
• 依托单位: University of British Columbia
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2018
• 资助国家: 加拿大
• 起止时间: 2018-01-01 至 2019-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=654743
• 关键词: Ecohydrological; Controls; Carbon; Drainage; Fluxes

Carbon is transported by water from terrestrial ecosystems to freshwater aquatic ecosystems through carbon drainage fluxes. The study of carbon drainage fluxes also involves consideration of subsequent downstream transport of carbon, as well as the loss of carbon to the atmosphere via emissions of carbon dioxide (CO2) or methane (CH4) from the water surface. Improving our understanding of carbon drainage fluxes between the biosphere, hydrosphere and the atmosphere is necessary to discern anthropogenic impacts on the water and carbon cycles, as well as the climate system. **My research program focuses on in situ carbon measurements in surface water and groundwater in temperate and tropical environments. It also examines the physical processes that control these fluxes. We will investigate key components of carbon drainage fluxes that are important to resolving the carbon balance at a watershed scale, and which contribute to our process-based knowledge of carbon and water interactions. In doing so, we will also develop several analytical tools and techniques that we anticipate to be highly transferable beyond this program that will significantly advance the field of ecohydrology. **Our central hypothesis is that changes in the forms and fluxes of carbon transported by water can be used to evaluate impacts resulting from climatic and land use change. Four studies are proposed to address this hypothesis in relation to our long-term objective of assessing carbon and water interactions in natural and human-impacted watersheds. *[A] Evaluate groundwater fluxes of dissolved CO2 in relation to watershed-scale controls on CO2 production and transport; *[B] Characterize dissolved organic carbon (DOC) in terms of DOC concentration and characteristics in soils, groundwater and surface water;*[C] Assess physical controls on emissions of CO2 and CH4 from surface water using two novel approaches: one for flowing water in headwater streams, and one for standing water in a wetland environment; *[D] Investigate changes in carbon drainage fluxes over time in a watershed recovering from disturbance. **In our studies, the biogeochemical characteristics of carbon drainage fluxes will be evaluated to assess if the carbon is likely to be transported downstream or released to the atmosphere via evasion from the water surface. Our analysis of dissolved CO2 concentration dynamics in groundwater adjacent to streams represents a novel approach for assessing the ecohydrological properties of a watershed, while research on DOC chemical characteristics (termed DOC quality) will allow for an assessment of the ecohydrological functioning of a watershed by tracking DOC quality during storm events. **We will characterize DOC quality in terms of its reactivity and bioavailability in order to (i) characterize terrestrial DOC inputs to aquatic ecosystems, and (ii) evaluate the potential for DOC to form disinfection byproducts such as trihalomethanes (THMs) in municipal water supplies. THMs are environmental pollutants resulting from reactions between some forms of DOC and chlorine or bromine during water treatment. THMs pose risks to human health, and the ecohydrological processes to be studied in this program of research appear to play a key role in the transport of DOC with a high THM formation potential.**The proposed program of study incorporates training of highly qualified personnel at BSc, MSc, PhD and PDF levels, and provides opportunities for scientific innovation appropriate for the emerging era of "big data". Training will involve (i) novel use of environmental sensors, data management and time series analysis, and (ii) professional development in mentoring and science communication.

陆地生态系统中的碳通过碳排放通量由水输送到淡水水生生态系统。碳排放通量的研究还涉及考虑随后的下游碳运输，以及通过从水面排放二氧化碳（CO2）或甲烷（CH 4）而损失到大气中的碳。提高我们对生物圈、水圈和大气层之间碳排放通量的理解，对于辨别人类活动对水和碳循环以及气候系统的影响是必要的。** 我的研究项目主要集中在温带和热带环境中地表水和地下水的原位碳测量。它还研究了控制这些通量的物理过程。我们将研究碳排放通量的关键组成部分，这些组成部分对解决流域尺度的碳平衡非常重要，并且有助于我们基于过程的碳和水相互作用的知识。在此过程中，我们还将开发几种分析工具和技术，我们预计这些工具和技术将在本计划之外具有高度可转移性，从而大大推进生态水文学领域的发展。** 我们的核心假设是，通过水输送的碳的形式和通量的变化可以用来评估气候和土地利用变化造成的影响。提出了四项研究来解决这一假设，我们的长期目标是评估自然和人类影响的流域的碳和水的相互作用。*[A]评估与流域尺度控制CO2产生和迁移有关的溶解CO2的地下水通量; *[B]根据土壤、地下水和地表水中溶解有机碳的浓度和特性，确定溶解有机碳的特征;*[C]使用两种新方法评估对地表水CO2和CH 4排放的物理控制：一个用于源头溪流中的流动水，一个用于湿地环境中的静水; *[D]研究从干扰中恢复的流域中碳排放通量随时间的变化。** 在我们的研究中，将评估碳排放通量的生物地球化学特征，以评估碳是否可能从水面逃逸到下游或释放到大气中。我们的分析溶解CO2浓度动态地下水邻近流代表了一种新的方法，用于评估流域的生态水文特性，而DOC化学特性（称为DOC质量）的研究将允许通过跟踪DOC质量在风暴事件的流域生态水文功能的评估。** 我们将根据DOC的反应性和生物利用度来表征DOC的质量，以便（i）表征陆地DOC输入水生生态系统的特征，以及（ii）评估DOC在市政供水中形成消毒副产品（如三卤甲烷（THMs））的潜力。三卤甲烷是在水处理过程中某些形式的DOC与氯或溴反应产生的环境污染物。THMs对人类健康构成风险，本研究计划中要研究的生态水文过程似乎在DOC的运输中发挥关键作用，具有高THM形成潜力。拟议的研究计划包括在理学士，硕士，博士和PDF水平的高素质人才的培训，并提供适合“大数据”的新兴时代的科学创新的机会。培训将涉及（i）环境传感器的新用途，数据管理和时间序列分析，以及（ii）指导和科学传播方面的专业发展。