Mapping global inputs and impacts from of human sewage in coastal ecosystems

Abstract

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. Few studies have assessed impacts of human wastewater on coastal ecosystems and community health. As such, we lack a comprehensive, fine-resolution, global assessment 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. Because solutions depend on the source, we separate nitrogen and pathogen inputs from sewer, septic, and direct inputs. Our model indicates that wastewater adds 6.2Tg nitrogen into coastal waters, which is approximately 40% of total nitrogen from agriculture. Of total wastewater N, 63% (3.9Tg N) comes from sewered systems, 5% (0.3Tg N) from septic, and 32% (2.0Tg N) from direct input. We find that just 25 watersheds contribute nearly half of all wastewater N, but wastewater impacts most coastlines globally, with sewered, septic, and untreated wastewater inputs varying greatly across watersheds and by country. Importantly, model results find that 58% of coral and 88% of seagrass beds are exposed to wastewater N input. Across watersheds, N and FIO inputs are generally correlated. However, our model identifies important fine-grained spatial heterogeneity that highlight potential tradeoffs and synergies essential for management actions. Reducing impacts of nitrogen and pathogens on coastal ecosystems requires a greater focus on where wastewater inputs vary across the planet. Researchers and practitioners can also overlay these global, high resolution, wastewater input maps with maps describing the distribution of habitats and species, including humans, to determine the where the impacts of wastewater pressures are highest. This will help prioritize conservation efforts.Without such information, coastal ecosystems and the human communities that depend on them will remain imperiled.

Mitigating local human impacts promotes coral reef persistence under climate change

“…4b). Pollution from human waste is a major source of human impacts to coastal marine ecosystems globally 43 , and is especially impactful from untreated sources (e.g., septic tanks and cesspools) that are common in Hawaiʻi 44 . Consequently, high concentrations of inorganic nutrients and pathogens leach into Hawaiʻi's coastal waters on a daily basis 44,45 , threatening coral reefs and posing a risk to human health 46 .…”

Gluconobacter Oxydans-Based MFC with PEDOT:PSS/Graphene/Nafion Bioanode for Wastewater Treatment

“…Wastewater treatment will be one of the most important tasks for humanity in the near future [ 1 , 2 , 3 ]. The use of traditional technologies (e.g., coagulation, adsorption and ion exchange membranes) for wastewater treatment does not always contribute to the complete removal of pollutants, so they re-enter the environment [ 4 ].…”

Energía eléctrica a partir de aguas residuales industriales en Guayaquil, Ecuador

“…En otra instancia en el estudio efectuado por Tuholske et al, (2021) se encontró que las aguas residuales agregan alrededor de 6,2 millones de toneladas anuales de nitrógeno a las aguas costeras del mundo. El nitrógeno es uno de los peores contaminantes de los océanos del planeta, ya que causa proliferación tóxica de algas, eutrofización y zonas muertas.…”

“…El nitrógeno es uno de los peores contaminantes de los océanos del planeta, ya que causa proliferación tóxica de algas, eutrofización y zonas muertas. Asimismo, estos investigadores destacan que la contaminación por aguas residuales contribuye a la contaminación de nutrientes por nitrógeno, la degradación de la biodiversidad, el daño a los sistemas de agua dulce, la contaminación por nuevas entidades químicas y el cambio climático Tuholske et al, (2021).…”

“…De allí pues, que afirma este organismo que la tarea de llevar saneamiento seguro para todos está rezagada, cerrar esta brecha es un compromiso para alcanzar los Objetivos de Desarrollo Sostenible (ODS) (BID, 2019). Según, Tuholske et al, (2021) el 63 % de la contaminación mundial por nitrógeno generada por aguas residuales proviene de los sistemas de alcantarillado; el 32 %, de la salida directa; y el 5 %, de los sistemas sépticos. Adicionalmente estos autores señalan que el problema es causado por la falta de acceso a un saneamiento adecuado, así como a sistemas de tratamiento que están obsoletos o no están diseñados para eliminar los nutrientes y otros contaminantes de los desechos Tuholske et al, (2021).…”