Characterisation of the nature, origins and ecological significance of dissolved organic matter in freshwater ecosystems

有证据表明，流向内陆和沿海水域的营养物质流量在全球范围内正在增加。尽管管理部门做出了大量努力来减少这些通量，但欧洲一些流域的N&P浓度最近趋于稳定或下降，但另一些流域的N&P浓度据报道有所增加，特别是在流经快速发展的经济区域的河流。进入淡水和沿海地区(如波罗的海)的溶解有机碳(DOC)通量的上升趋势也被广泛报道，特别是在北部温带和北部地区。在淡水和沿海水域，对生态系统健康的影响是广泛和不可取的，在DOC和DON也被认为支持水中致癌物质形成的地方，对人类健康也有影响。在欧洲，为了实现根据欧盟水框架指令将水域恢复到良好生态状态的目标，需要控制流向所有淡水和沿海地区的营养物质通量，而联合国欧洲经济委员会关于远程越境空气污染的公约(CLRTAP)目前正在修订哥德堡议定书附件九(以减少酸化、富营养化和地面臭氧)，以进一步减少陆上活动中的氨排放。与此同时，联合国已将沿海营养物质污染和缺氧列为当前对全球环境的最大威胁之一。影响包括沿海水域的富营养化和氧气枯竭，以及对生态系统、生物多样性和沿海水质的相关损害。联合国环境规划署《马尼拉宣言》(2012年1月)将海洋环境的营养物质富集化确定为其保护海洋环境免受陆上活动影响的全球行动纲领的3个重点之一，这也是2012年6月里约20届联合国可持续发展会议的主要重点之一。如果我们要通过管理干预来控制这些影响，对向水域输送营养物质的性质、来源和速率的详细了解是至关重要的，然而，许多必要的证据基础都是缺乏的。常规水质监测主要基于无机营养成分，大大低估了进入水域的总营养通量，而研究证实，溶解有机物(DOM)在生态系统功能中发挥着重要作用，包括支持微生物新陈代谢、初级生产和污染物传输，这表明在常规监测中的疏忽可能会破坏控制营养物质丰富影响的国际努力。在这里，我们基于项目成员的具体专业知识，开展从分子到流域规模的一系列相互关联的实验和观测研究。我们将结合在流域研究中广泛使用的成熟方法，以及在营养循环研究中应用新颖的一系列尖端方法，或采用新技术，为在分子到河流尺度上的营养循环过程控制带来新的见解。该计划将提供以下方面的更好理解：1.DOM在N&P从源到海洋的运输中的作用及其在气候变化下可能改变向淡水和海岸地带的营养输送的方式；2.在营养状况和DOM特征不同的水域中，DOM作为藻类、植物和微生物群落吸收和利用养分的来源的生态意义；以及3.DOM的生态意义。来自土壤、牲畜和人类排泄物的DOM通量对淡水提供的生态状况、货物和服务的影响。它还将促进5个小组和更广泛的科学界之间的知识交流，并在本项目结束后产生影响，通过任命工作人员和博士在当前理解不确定的领域进行能力建设，破坏商业规划和国际政策制定。

Evidence indicating that nutrient flux to inland and coastal waters is increasing worldwide is clear. Despite significant management effort to reduce theses fluxes, while N & P concentrations have recently levelled off or decreased in some European catchments, in others an increase is reported, particularly in rivers draining through rapidly developing economic regions. A rising trend in Dissolved Organic Carbon (DOC) flux to freshwaters & coastal areas such as the Baltic Sea is also widely reported, particularly in the N Temperate & Boreal regions. Impacts on ecosystem health are extensive & undesirable in both freshwaters & coastal waters, & there are implications for human health where DOC & DON are also known to support carcinogen formation in water supplies.In Europe the control of nutrient flux to all freshwaters & the coastal zone is required in order to meet the target of restoring waters to Good Ecological Status under the EU Water Framework Directive, while the UNECE Convention on Long-Range Transboundary Air Pollution (CLRTAP) is currently revising Annex IX of the Gothenburg Protocol (to Abate Acidification, Eutrophication & Ground-level Ozone) to further reduce the emission of ammonia from land-based activities.Simultaneously, the UN has listed coastal nutrient pollution and hypoxia as the one of the greatest current threats to the global environment. Impacts include eutrophication of coastal waters and oxygen depletion, and the associated damage to ecosystems, biodiversity & coastal water quality. The UNEP Manila Declaration (Jan 2012) identifies nutrient enrichment of the marine environment as one of 3 foci for its Global Programme of Action for the Protection of the Marine Environment from Land-based Activities, and this was one of the key foci at the Rio+20 UN Conference on Sustainable Development, June 2012.A detailed understanding of the nature, origins & rates of nutrient delivery to waters is essential if we are to control these impacts through management intervention, yet much of the necessary evidence base is lacking. Routine water quality monitoring is largely based on inorganic nutrient fractions, and substantially underestimates the total nutrient flux to waters, while research confirms that dissolved organic matter (DOM) plays an important role in ecosystem function including supporting microbial metabolism, primary production and pollutant transport, suggesting that its oversight in routine monitoring may undermine international efforts to bring nutrient enrichment impacts under control.Here, we address this knowledge gap, building on the specific expertise of project members, undertaking a suite of interlinked experimental & observational research from molecular to catchment scale. We will use a combination of well-established approaches widely used in catchment research, with a range of cutting-edge approaches which are novel in their application to nutrient cycling research, or employ novel technologies, bringing new insights into the process controls on nutrient cycling at a molecular to river reach scale.The programme will deliver improved understanding of:1. the role of DOM in the transport of N & P from source to sea & the ways in which this might alter nutrient delivery to freshwaters & the coastal zone under a changing climate;2. the ecological significance of DOM as a source of nutrient uptake & utilisation by algal, plant and microbial communities in waters of contrasting nutrient status & DOM character; and3. the impacts of DOM flux from soils, livestock & human waste fluxes on the ecological status, goods & services provided by freshwaters.It will also deliver knowledge exchange between the 5 groups & the wider science community, and have an impact beyond the lifetime of this project, building capacity through staff & PhD appointments in a field where current understanding is uncertain, undermining business planning and international policy development.