The State of Our Oceans

pollutants entering the oceans

Coastal waters receive a variety of land-based water pollutants, ranging from petroleum wastes to pesticides to excess sediments. Marine waters also receive wastes directly from offshore activities, such as ocean-based dumping (e.g., from ships and offshore oil and gas operations).

One pollutant in the ocean is sewage. Human sewage largely consists of excrement from toilet-flushing; wastewater from bathing, laundry, and dishwashing; and animal and vegetable matter from food preparation that is disposed through an in-sink garbage disposal. Because coasts are densely populated, the amount of sewage reaching seas and oceans is of particular concern because some substances it contains can harm ecosystems and pose a significant public health threat. In addition to the nutrients which can cause overenrichment of receiving waterbodies, sewage carries an array of potentially disease-causing microbes known as pathogens.

Animal wastes from feedlots and other agricultural operations (e.g., manure-spreading on cropland) pose concerns similar to those of human wastes by virtue of their microbial composition. Just as inland rivers, lakes, and groundwater can be contaminated by pathogenic microbes, so can coastal waters. Runoff from agricultural areas also contains nutrients such as phosphorus and nitrogen, which can cause overenrichment in coastal regions that ultimately receive the runoff.

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