Hypoxia - a world-wide problem

摘要

When water-borne nutrients reach coastal areas, they can impact ecosystems in a number of ways. Common effects include excess growth of phytoplankton, micro algae and macro algae. Hypoxia can occur when these algae and other organisms die, sink to the bottom, and are decomposed by bacteria, using up the available dissolved oxygen. Salinity and temperature differences between surface and subsurface waters lead to stratification, which limits oxygen replenishment from surface waters. Nutrient sources include agricultural runoff, human sewage, industrial effluent, urban stormwater runoff, and fossil fuel consumption. In the United States, animal manure and fertilizer are the most common sources of nutrients.