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

有证据表明，全世界流入内陆和沿海沃茨的营养物质正在增加。尽管为减少这些通量作出了重大的管理努力，但在一些欧洲集水区，氮磷浓度最近趋于稳定或有所下降，但据报告，其他集水区的氮磷浓度有所增加，特别是在流经快速发展的经济地区的河流中。溶解有机碳（DOC）通量上升的趋势，如波罗的海的淡水和沿海地区也被广泛报道，特别是在北温带和北方地区。在淡水沃茨和沿海沃茨中，对生态系统健康的影响是广泛的和不希望的，并且对人类健康也有影响，其中DOC和DON也被认为支持供水中的致癌物形成。在欧洲，为了满足根据欧盟水框架指令将沃茨恢复到良好生态状态的目标，需要控制营养物通量到所有淡水沃茨和沿海区。联合国欧洲经济委员会《远距离越境空气污染公约》（CLRTAP）目前正在修订《减少酸化、富营养化和地面臭氧的哥德堡议定书》附件IX，以进一步减少陆地活动产生的氨排放。同时，联合国已将沿海营养物污染和缺氧列为当前全球环境面临的最大威胁之一。影响包括沿海沃茨的富营养化和氧气消耗，以及对生态系统、生物多样性和沿海水质的相关损害。环境署马尼拉宣言（2012年1月）将海洋环境的营养富集确定为其《保护海洋环境免受陆上活动污染全球行动纲领》的三个重点之一，这也是2012年6月里约+20联合国可持续发展大会的重点之一。如果我们要通过管理干预来控制这些影响，营养物输送到沃茨的来源和速度是必不可少的，但缺乏许多必要的证据基础。常规水质监测主要基于无机营养盐组分，大大低估了沃茨的总营养盐通量，而研究证实溶解性有机物（DOM）在生态系统功能中起着重要作用，包括支持微生物代谢，初级生产和污染物迁移，这表明，它在例行监测中的疏忽可能会破坏国际社会为控制营养富集影响所做的努力。在这里，我们解决这一知识差距，建立在项目成员的具体专业知识的基础上，开展了一套从分子到流域规模的相互关联的实验和观察研究。我们将结合广泛应用于流域研究的成熟方法，以及一系列应用于养分循环研究的前沿方法，或采用新技术，为从分子到河流尺度的养分循环过程控制带来新的见解。该计划将提高对以下方面的理解：1. DOM在N & P从源到海的运输中的作用以及在气候变化下这可能改变营养物向淡水和沿海地区输送的方式;2. DOM作为藻类、植物和微生物群落对营养盐吸收和利用的来源，在营养盐状况和DOM特征截然不同的沃茨中的生态学意义;来自土壤、牲畜和人类废物的DOM通量对淡水生态状况、商品和服务的影响。它还将在5个小组和更广泛的科学界之间进行知识交流，并产生超出本项目生命周期的影响，通过在目前理解不确定的领域任命工作人员和博士来建设能力，破坏商业规划和国际政策的制定。

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.