The freshwater phosophorus cycle and the fate of water-borne pathogens

在拟议的NSERC发现补助金的任期内，三名博士生将对湖泊和河流中的磷循环进行研究，一名将研究河流中病原微生物的持久性。 在多塞特环境科学中心，我们将使用与以前的NSERC DG资金开发的新技术，以确定哪些环境因素决定浮游生物中细菌和藻类的磷酸盐浓度，从而决定其生产力。 首先，我们将解决的假设，食物网结构和光（由混合深度和水的透明度决定）是关键变量。 我们将在DESC解决的第二个基本问题是磷在湖泊上层的停留时间，因此，对于给定的营养负荷，生物量的总量将存在。 要做到这一点，我们将利用天然存在的放射性同位素，可用于测量年龄的磷在表层。 富营养化河流的一个主要环境问题是由于污水和农业的高磷负荷导致水生植物生物量过剩，导致夜间溶解氧低。 要了解磷酸盐浓度可用于植物在夏季低流量期间，当营养物质可能控制植物生长，我们将估计有多少在夏季低流量的P被隔离在不同的社区，我们将确定这些是否是一个净源或汇磷酸盐作为磷酸盐浓度的函数。 这项研究将导致一个模型预测磷酸盐浓度在低流量的河流与不同的相对丰度，这些社区。 沃茨中病原体的浓度取决于载量和持久性。我们将研究不同的水生群落对病原体的去除，包括悬浮物、沉积物、硬表面上的生物膜以及与水生植物相关的生物膜。 这些信息将告知河流社区如何与病原体负荷相互作用，以确定病原体水平。

During the tenure of the proposed NSERC Discovery Grant, three PhD students will conduct research on the phosphorus cycle in lakes and rivers, and one will work on the persistence of pathogenic microbes in rivers.  At the Dorset Environmental Science Centre we will use new techniques developed with previous NSERC DG funding to determine what environmental factors determine the concentration of phosphate available to bacteria and algae in the plankton, and hence their productivity.  Initially, we will address the hypothesis that food web structure and light (determined by mixing depth and water transparency) are the key variables.  The second fundamental problem we will address at DESC is the residence time of P in the epilimnion of lakes and therefore the total amount of biomass that will be present for a given nutrient loading.  To do this we will exploit naturally occurring radioisotopes that can be used to measure the age of P in the epilimnion.   A major environmental problem for eutrophic rivers is excess biomass of aquatic plants caused by high phosphorus loading from sewage and agriculture, leading to low dissolved oxygen at night.  To understand phosphate concentration available to plants during summer low flow periods, when nutrients likely control plant growth, we will estimate how much of the P at summer low flow is sequestered in different communities, and we will determine whether each of these is a net source or sink for phosphate as a function of phosphate concentration.  This research will lead to a model predicting phosphate concentrations at low flow for rivers with different relative abundances of these communities.   Concentrations of pathogens in surface waters are determined by both loading and persistence. We will study the removal of pathogens by different aquatic communities, including seston, sediments, biofilms on hard surfaces, and biofilms associated with macrophytes.  This information will inform as to how river communities interact with pathogen loading to determine pathogen levels.