90Y/90Sr and 234Th/238U disequilibria: Using dual chronometers to measure the effect of invasive dreissenid mussels on particle dynamics in Lake Michigan.

在这个项目中，位于密尔沃基的威斯康星州大学的研究人员将继续研究密歇根湖近岸沃茨中颗粒及其相关营养物质和能量的通量、路径和停留时间。 他们的总体目标是进一步探索使用双快过程计时器（90 Y/90 Sr）和234 Th/238 U不平衡）作为快速粒子动力学的示踪剂。在密歇根湖，dreissenid贻贝现在占主导地位，这些近岸动态和项目目标，因此，集中在这种影响。 有三个具体目标：（1）研究原位底栖贻贝种群密度对水体中原位颗粒（营养物）去除的影响。(2)研究在季节性变化的热条件下，原位底栖贻贝种群对原位颗粒（营养物质）去除的影响。 (3)检查贻贝过滤颗粒（粪便和假粪便形式）的停留时间和近岸非沉积湖床上的90 Y和234 Th的库存。更广泛的影响：沿海地区正受到日益严重的营养和毒性压力，发展和改进在短时间尺度上追踪悬浮物质的技术将广泛适用于五大湖和海洋生物地球化学。了解污染物的迁移也与人们对水安全的高度关切有关，特别是在五大湖，近4 000万人从那里饮用水。放射性核素作为示踪剂用于跟踪和量化环境过程是一个不断扩展的领域，新的放射性核素技术在湖沼学、海洋学、地下水和地表水水文学以及陆-水系统耦合中具有广泛的应用潜力。这些工具是环境研究工具箱的重要组成部分。 五大湖区域能够进行辐射测量的实验室相对较少;提高这一能力具有区域重要性。

In this project, researchers at the University of Wisconsin at Milwaukee will continue their research into the fluxes, pathways and residence times of particles and their associated nutrients and energy in nearshore waters of Lake Michigan. Their overall objective is to further explore the use of dual fast process chronometers (90Y/90Sr) and 234Th/238U disequilibria) as tracers of rapid particle dynamics. In Lake Michigan, dreissenid mussels now dominate these nearshore dynamics and the project objectives, therefore, focus on this influence. There are three specific objectives: (1) Examine what effect the in situ benthic mussel population density has on in situ particle (nutrient) removal from the water column. (2) Examine what effect an in situ benthic mussel population has on in situ particle (nutrient) removal under seasonally changing thermal conditions. (3) Examine the residence time of mussel-filtered particles (in the form of feces and pseudo-feces) and the inventory of 90Y and 234Th on the nearshore non-depositional lake bed. Broader Impacts: Coastal zones are under increasing nutrient and toxic stress, and developing and improving techniques for tracking suspended materials on short time-scales will have broad applicability in both Great Lakes and marine biogeochemistry. Understanding the transport of contaminants is also relevant to the heightened concerns over water security, particularly in the Great Lakes from which nearly 40 million people draw drinking water. The utility of radionuclides as tracers for following and quantifying environmental processes is an expanding field, and novel radionuclide techniques have wide potential application in limnology, oceanography, ground water and surface water hydrology, and terrestrial-aquatic system coupling. These tools are an essential component of the environmental research toolbox. Relatively few laboratories in the Great Lakes region are capable of making radiometric measurements; improving this capability has regional importance.