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

人类活动正在增加世界各地内陆水生网络(河流、湖泊和水库)的含盐量，其生物地球化学影响复杂而不明确。例如，阳离子和阴离子(如硫酸盐)浓度的增加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，从而影响生物可获得性和材料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为我的总体研究计划提供独特的支持。具体地说，该计划旨在解决盐碱化对大陆水生生态系统中生物活性硫、有机物(OM)和净温室气体(GHG)产生的影响。确定盐碱化趋势及其对水生生物地球化学过程的影响对加拿大和世界各地的生物地球化学家和生态学家至关重要，因为盐碱化是一个强有力的全球普遍问题，对生态系统功能有无数影响。这项拟议的研究将通过解决4个短期目标来确定生态系统盐碱化与有机污染物和温室气体循环之间的联系：1)量化盐度、硫酸盐有效性和二甲基硫化物(DMS)循环之间的关系；(2)阐明离子强度和组成对甲烷(CH4)循环的影响。3)量化盐碱化对水生有机质循环的影响。4)将盐碱化变化与温室气体全网络、多气体通量联系起来。在加拿大河网模型中应用这些目标，将有助于定义盐碱化如何改变大陆景观中的生态系统过程。我们将从Oldman River Network的新的和现有的采样以及水生研究设施(U.Lethbridge)的受控实验中收集数据。这些信息将为人类对对比元素循环(例如，硫、碳、氮、磷)的影响提供关键的新见解，这是全球生物地球化学仍未得到解决的一个方面。这项研究还将有助于确定综合水产网络的大气变暖潜力，从而为跟踪大气温室气体含量变化的全球倡议作出贡献。确定盐度对有机质生物有效性的影响将提供对水生生物地球化学功能的重要洞察，因为有机质池的开发是温室气体产生的前兆，也是支持生态系统生产力和碳固存的主要营养来源。在盐碱化的不同情景下，更好地了解有机质的生物有效性，将对侧重于减轻富营养化的水质监测工作产生实际好处，富营养化是大平原北部以农业为主的景观的核心问题。

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.