Great Lakes Restoration Initiative Project 49 Fox River Basin 2016 and 2017 Data

The Fox River transports elevated loads of nitrogen and phosphorus to Lake Michigan. The increased concentration of N and P causes eutrophication of the lake, creating hypoxic zones and damaging the lake ecosystem.To decrease loading, best management practices (BMPs) have been implemented in the uplands of the basin. Little work has been done, however, to reduce nutrient concentrations in the river. Rivers are capable of removing nutrients through biotic uptake and sediment burial and are able to remove N through denitrification. Identifying and managing these locations of increased nutrient cycling known as “hot spots” may be another mechanism for nutrient mitigation.Our objective was to identify hot spots of N and P cycling in the Fox River basin. We measured rates of specific biogeochemical processes (e.g. ambient and potential denitrification, and sediment phosphorus uptake and release) at sites that had varying mixed land use. We also measured variables that are known to affect nitrogen and phosphorus cycling. Models were created to estimate how land use type and BMP coverage can effect the capacity of the Fox River and its tributaries to retain and cycle N and P.

福克斯河（Fox River）向密歇根湖输送了高负荷的氮与磷。氮、磷浓度升高会引发密歇根湖富营养化，形成缺氧区并破坏湖泊生态系统。为降低营养盐负荷，该流域高地已实施最佳管理措施（Best Management Practices, BMPs）。然而，目前针对河流内营养盐浓度削减的研究仍较为匮乏。河流可通过生物摄取与沉积物埋藏去除营养盐，还可通过反硝化作用脱除氮素。识别并管控这类被称为‘热区（hot spots）’的营养盐循环增强区域，或许是另一种营养盐减排途径。本研究旨在识别福克斯河流域内氮、磷循环的热区。我们在不同混合土地利用类型的监测点位，测定了特定生物地球化学过程的速率，包括原位反硝化与潜在反硝化速率、沉积物磷摄取与释放速率。同时，我们还测定了已知会影响氮、磷循环的各类环境变量。本研究构建了模型，以评估土地利用类型与最佳管理措施覆盖度如何影响福克斯河及其支流的氮、磷留存与循环能力。