Salinization of Canadian Prairie Surface Waters: Biogeochemical impacts and Ecosystem Outcomes

人类活动正在增加全世界内陆水生网络（河流、湖泊和水库）的含盐量，其生物地球化学影响复杂且不明确。例如，增加阳离子和阴离子的浓度（例如，硫酸盐）可能会改变生态系统的氧化还原特性、食物网的组成和功能以及物理化学特性，从而影响生物利用率和物质在大陆景观中的流动。 我的长期研究计划旨在了解人类对支撑水生生态系统健康和功能的生物地球化学过程的综合影响。本文提出的计划旨在独特地支持我的总体研究计划。具体而言，该计划旨在解决盐渍化对大陆水生生态系统中生物反应性硫，有机物（OM）和净温室气体（GHG）产生的影响。确定盐渍化的趋势和对水生生态地球化学过程的影响是至关重要的生态地球化学家和生态学家在加拿大和世界各地，因为盐渍化是一个强大的和全球性的问题，对生态系统功能有无数的影响。拟议的研究将确定生态系统盐渍化和OM和温室气体循环之间的连接在一个模型加拿大草原水生网络解决4个短期目标：1）量化之间的关系盐度，硫酸盐的可用性，和二甲基硫（DMS）循环; 2）阐明离子强度和组成对甲烷（CH 4）循环的影响。 3)量化盐渍化对水生有机质循环的影响。 4)将盐渍化变化与温室气体的整个网络、多气体通量联系起来。 这些目标，适用于加拿大河流网络模型，将有助于确定如何盐碱化正在改变大陆景观的生态系统过程。我们将收集来自奥德曼河网络中新的和现有的采样数据，以及来自水生研究设施（美国）的受控实验数据。Lethbridge）。这些信息将为人类对对比元素周期的影响提供重要的新见解（例如，硫、碳、氮、磷），这是全球地球化学的一个方面，仍然没有得到很好的解决。这项研究还将有助于确定综合水生网络的大气升温潜力，从而有助于跟踪大气温室气体含量变化的全球倡议。确定盐度对有机质生物利用度的影响将为水生生物地球化学功能提供重要的见解，因为有机质库的发展是温室气体产生的前体，也是支持生态系统生产力和碳固存的营养物质的主要来源。在盐碱化的对比情景下，对OM生物利用度的进一步了解将对水质监测工作产生实际效益，重点是减轻富营养化，这是农业主导的北方大平原景观的核心问题。

Human activities are increasing the salt content of inland aquatic networks (rivers, lakes, and reservoirs) worldwide, with complex and unclear biogeochemical implications. For example, increasing concentrations of cations and anions (e.g., sulfate) may alter the redox properties of ecosystems, the composition and functioning of food webs, and physico-chemical properties in ways that affect the bio-availability and flow of materials through continental landscapes. My long-term research program aims to understand integrated human impacts on biogeochemical processes underpinning aquatic ecosystem health and functioning. The plan presented herein is designed to uniquely support my overarching research program. Specifically, this program is designed to address salinization impacts on bio-reactive sulfur, organic matter (OM), and net greenhouse gas (GHG) production in continental aquatic ecosystems. Defining the trends of salinization and effects on aquatic biogeochemical processes is critical for biogeochemists and ecologists across Canada and throughout the world, since salinization is a potent and globally widespread problem that has myriad effects on ecosystem functioning. The proposed research will define the connection between ecosystem salinization and cycling of OM and GHGs in a model Canadian Prairie aquatic network by addressing 4 short-term objectives: 1) Quantifying relations between salinity, sulfate availability, and dimethylsulfide (DMS) cycling;  2) Elucidating effects of ionic strength and composition on methane (CH4) cycling. 3) Quantifying salinization effects on aquatic OM cycling. 4) Linking salinization changes to whole-network, multi-gas fluxes of GHGs. These objectives, applied within a model Canadian river network, will help define how salinization is changing ecosystem processes in continental landscapes. We will assemble data from new and existing sampling in the Oldman River Network, and from controlled experimentation at the Aquatic Research Facility (U. Lethbridge). This information will provide critical new insights into human impacts on contrasting elemental cycles (e.g., sulfur, carbon, nitrogen, phosphorus), an aspect of global biogeochemistry that remains poorly resolved. This research will also help define the atmospheric warming potential of integrated aquatic networks, thereby contributing to global initiatives tracking changes in atmospheric GHG content. Defining salinity impacts on OM bioavailability will provide critical insight into aquatic biogeochemical functioning, since development of OM pools is the precursor for GHG production, and a major source of nutrients supporting ecosystem productivity and carbon sequestration. Improved understanding of OM bioavailability under contrasting scenarios of salinization will have practical benefits for water quality monitoring efforts focused on abatement of eutrophication, a central issue for agriculturally dominated Northern Great Plains landscapes.