Global Inputs and Impacts from of Human Sewage in Coastal Ecosystems

Coastal marine ecosystems face a host of pressures from both offshore and land-based human activity. Research on terrestrial threats to coastal ecosystems has primarily focused on agricultural runoff, specifically showcasing how fertilizers and livestock waste create coastal eutrophication, harmful algae blooms, or hypoxic or anoxic zones. These impacts not only harm coastal species and ecosystems but also impact human health and economic activities. Yet few studies have assessed impacts of human wastewater on coastal ecosystems and community health. As such, we have lacked a comprehensive, fine-resolution, global assessment of the inputs and impacts of human sewage inputs that captures both pathogens and nutrient flows to coastal waters and the potential impacts on coastal ecosystems. To address this gap, we use a new high-resolution geospatial model to measure and map nitrogen (N) and pathogen - fecal indicator organisms (FIO) - inputs from human sewage for ~135,000 watersheds globally. Our modeled data is for 2015.The resulting dataset provides N and FIO wastewater inputs for each watershed globally. The dataset separates the contribution from sewered, septic, and untreated (open deification) wastewater inputs to coastal waters. Data is provided at the watershed level, as well as the coastal 'pourpoint' (the location where the watershed empties into the ocean), as vector shape files (.shp). Furthermore, we provide a global raster of N coastal impacts created by propagating pourpoint N inputs into the coastal waters using a plume model based on a logarithmic decay function. The effluent plumes can be used to determine the extent to which different marine habitats are exposed to wastewater N.For full information, see: *Tuholske, C., *Halpern, B., Blasco, G., Villasenor, J. C., Frazer, M., & Caylor, K. (In revision). Mapping global sources and impacts of sewered, septic and direct wastewater in coastalecosystems. PLOS One.*Equal authorship