Application of targeted transcriptomics for determining early nutrient sediment retention capacity (NSRC)

减少营养物质及其截留是水源保护的主要目标，也是有效污水处理、工程蓄水流域和农业最佳做法的主要目标。重点往往放在监测水中的营养物来源和浓度上。然而，在湖泊、湿地和工程系统(如蓄水池、人工湿地、排水沟)中，与沉积物水库长期固存的营养物质动员相关的风险并未得到很好的了解。这些沉积物-营养动态可以显著影响浅层富营养化系统的内部营养负荷，并可能在外部负荷减弱后导致延迟恢复。沉积物中的养分循环在很大程度上是由微生物过程驱动的，要么直接通过将结合的养分转化为生物可利用形式，要么间接通过调节控制养分形态和溶解度的物理/化学条件来驱动。测量沉积物营养盐通量的经典方法往往忽略了调节沉积物营养盐保持能力的一组动态和复杂的微生物途径。该项目将与我们的合作者和工业合作伙伴一起，开发一种快速且经济高效的技术来诊断表层沉积物的营养保持能力，因为它与微生物基因表达(功能)和微生物群落组成有关。具体地说，该项目将开发一种有针对性的转录分析系统，该系统能够检测指示活性营养通量的诊断微生物基因表达谱，并可作为更昂贵和费力的经典化学方法的替代品。该分析将通过生成新的基因表达文库来设计系统，该文库可校准来自几个沉积物环境的原位微生物群落，包括农业支流/排水沟、工程保留系统和接受废水处理废水的支流。这些信息将为评估沉积物养分释放导致内部负荷的健康/潜在风险提供新的见解，这是伊利湖目前主要关注的问题，也是与气候变化有关的加拿大其他流域和全球流域预期的主要压力矢量。

Nutrient mitigation and their interception is a primary goal of source water protection and a main objective for effective sewage treatment, engineered water retention basins and agricultural best practice. Emphasis is often placed on monitoring nutrient sources and concentrations in water. However, the risks associated with nutrients mobilization from long-term sequestration in sediment reservoirs are not well understood in lakes, wetlands, and engineered systems (e.g. retention ponds, constructed wetlands, drainage ditches). These sediment-nutrient dynamics can significantly impact internal nutrient loading in shallow eutrophic systems and can cause delayed recovery after external loads have been abated. Nutrient cycling in sediment is driven largely by microbial processes, either directly by conversion of bound-nutrients to bioavailable forms or indirectly by regulating the physical/chemical conditions that control nutrient speciation and solubility. Classic approaches to measuring nutrient flux from sediments often overlook the dynamic and complex set of microbial pathways involved in regulating sediment nutrient retention capacity. With our Collaborators and Industrial Partners, this project will develop a rapid and cost effective technology to diagnose surficial sediment nutrient retention capacity as it relates to microbial gene expression (function) and microbial community composition. Specifically, this project will develop a targeted transcriptomic assay system capable of detecting diagnostic microbial gene expression profiles indicative of active nutrient flux and can serve as a proxy for more expensive and laborious classic chemical approaches. The assay will be system designed by generating novel gene expression libraries calibrated to in-situ microbial communities derived from several sediment environments including agricultural tributaries/drainage ditches, engineered retention systems and tributaries receiving wastewater treatment effluents. Such information will provide new insights for evaluating the health/potential risk of sediment-nutrient release leading to internal load, a current major concern for Lake Erie and a anticipated major stress vector in other Canadian and global watersheds related to climate change.