PAthways of Chemcials Into Freshwaters and their ecological ImpaCts (PACIFIC)

人造化学品对于维持公共卫生、粮食生产和生活质量至关重要，包括各种药品、农药和个人护理产品。这些化合物在整个社会的使用导致环境中的浓度和化学多样性不断增加。虽然人们一直关注化学品对淡水生物多样性子集（特别是无脊椎动物和鱼类）的影响，但我们对化学污染如何影响淡水微生物了解甚少。这些微生物群落（“微生物组”）的数量为每毫升水或每克沉积物数百万至数十亿个细胞，构成淡水生态系统中生物多样性最丰富且功能最重要的组成部分。淡水微生物提供的生物地球化学和生态功能对于更广泛的淡水生态系统健康至关重要。化学品进入淡水的途径及其生态影响（PACIFIC）项目将侧重于了解人为化学品的来源及其在淡水生态系统中的途径、归宿和生态影响之间的联系，重点是淡水微生物生态系统及其所发挥的功能。我们将研究预测的扩散和点源化学路径与泰晤士河和布里斯托尔雅芳流域各地的水和沉积物中测量的化学浓度之间的关系，选择代表扩散污染源的梯度。这些地点将选择与废水处理厂 (WwTW) 一致，以了解污水排放如何影响这些梯度的化学负荷。液相色谱法与（高分辨率）串联质谱法和 QTOF（四极杆飞行时间）质谱法相结合，将用于对已证实和怀疑影响淡水生态的化学基团进行靶向和非靶向分析。还将在每个地点测量一系列微生物群落生态系统端点，以识别化学品暴露的影响，包括通过 DNA 测序确定细菌和真菌群落组成、养分循环和化学胁迫和抗性基因的表达、与生物地球化学循环有关的细胞外酶的产生，以及整个微生物群落的功能基因库。我们将对淡水微生物群落进行实验性微观暴露，以增加复杂性和现实性，部署高通量筛选来识别新的化学基团（及其结构特征）具有重组这些社区的能力。将通过应用尖端分子技术来更详细地研究示例性微生物群落修饰化学品，以确定代表淡水微生物生态系统不同分类和功能方面的生态暴露阈值。基于新型现场的中生态系统将用于探索更现实但受控环境中的废水暴露，使我们能够探索化学污染如何与其他生态驱动因素（如营养物和温度）相互作用，以及微生物反应如何扩大到更高的营养水平并改变生态系统功能。扩散和点源化学污染途径的空间和时间放大模型将与实验室和现场暴露开发的新阈值相结合，以确定对淡水微生物的化学威胁，支持开发工具更好地管理化学污染对淡水生态系统健康的风险。这些将与未来的水文、气候和社会经济情景相结合，根据我们实验中的反应提供信息，并与项目合作者环境署共同开发，以探索微生物淡水生态系统和更广泛的生态系统健康的未来威胁。

Manufactured chemicals are essential for the maintenance of public health, food production and quality of life, including a diverse range of pharmaceuticals, pesticides, and personal care products. The use of these compounds throughout society has led to increasing concentrations and chemodiversity in the environment. Whilst there has been focus on understanding the impacts of chemicals on a subset of freshwater biodiversity (particularly invertebrates and fish), we understand less about how chemical pollution impacts freshwater microbes. These microbial communities (the 'microbiome') number in the millions to billions of cells per millilitre of water or gram of sediment and form the most biodiverse and functionally important component of freshwater ecosystems. The biogeochemical and ecological functions delivered by freshwater microbes are essential to wider freshwater ecosystem health. The PAthways of Chemicals Into Freshwaters and their ecological ImpaCts (PACIFIC) project will focus on understanding the link between sources of anthropogenic chemicals and their pathways, fate and ecological impacts in freshwater ecosystems, with an emphasis on freshwater microbial ecosystems and the functions they perform. We will investigate the relationship between predicted diffuse and point source chemical pathways and measured chemical concentrations in water and sediments at locations across the Thames and Bristol Avon catchments, chosen to represent gradients of diffuse pollution sources. These locations will be chosen to coincide with Wastewater Treatment Works (WwTWs) to understand how sewage effluent contributes to chemical burden across these gradients. Liquid chromatography coupled with (high resolution) tandem mass spectrometry and QTOF (quadrupole Time-of-Flight) mass spectrometry will be used to perform targeted and untargeted profiling of chemical groups proven and suspected to impact freshwater ecology. A range of microbial community ecosystem endpoints will also be measured at each location to identify the impact of chemical exposure, including bacterial and fungal community composition via DNA sequencing, the expression of nutrient cycling and chemical stress and resistance genes, the production of extracellular enzymes involved with biogeochemical cycling, and the functional gene repertoire of whole microbial communities.We will perform experimental microcosm exposures on freshwater microbial communities, with increasing complexity and realism, deploying high-throughput screening to identify novel chemical groups (and their structural features) with the capacity to restructure these communities. Exemplar microbial community modifying chemicals will be investigated in more detail by applying cutting-edge molecular techniques to determine ecological exposure thresholds that represent different taxonomic and functional aspects of freshwater microbial ecosystems. Novel field based mesocosms will be used to explore wastewater exposures in more realistic, but controlled settings, allowing us to explore how chemical pollution may interact with other ecological drivers such as nutrients and temperature, and how microbial responses scale-up to higher trophic levels and alter ecosystem functioning.Spatially and temporally up-scaled models of diffuse and point source chemical pollution pathways will be combined with novel thresholds developed from the lab and field exposures, to determine chemical threats to freshwater microbes, supporting the development of tools for the better management of the risks of chemical pollution to freshwater ecosystem health. These will be combined with future hydrological, climate and socio-economic scenarios, informed by responses in our experiments, and co-developed with project collaborators, the Environment Agency, to explore future threats to microbial freshwater ecosystems and wider ecosystem health.