Eutrophication and development, pollution from septic systems and sewers, sewage sludge spreading, and other human-related activities increase the flow of both inorganic nutrients and organic substances into ecosystems. Elevated levels of atmospheric compounds of nitrogen can increase nitrogen availability. Phosphorus is often regarded as the main culprit in cases of eutrophication in lakes subjected to "point source" pollution from sewage pipes. The concentration of algae and the trophic state of lakes correspond well to phosphorus levels in water. Studies conducted in the Experimental Lakes Area in Ontario have shown a relationship between the addition of phosphorus and the rate of eutrophication.
Cultural eutrophication Nova Scotia. In order to match an increase in food demand, agricultural production relies heavily on the use of fertilizers to increase overall crop productivity. These fertilizers contain high amounts of phosphorus and nitrogen, which results in excess amounts of nutrients entering the soil. The nutrients that are not absorbed by the plant leach out of the soil and enter freshwater systems, such as rivers. These nutrients can eventually end up in aquatic ecosystems, and are a contributor to increased eutrophication. Cultural eutrophication Cultural eutrophication is the process that speeds up natural eutrophication because of human activity. Due to clearing