nonpoint source pollution nonpoint source pollution nonpoint source (nps) pollution refers to diffuse contamination (or pollution) of water or air that does not originate from a single discrete source. this type of pollution is often the cumulative effect of small amounts of contaminants gathered from a large area. it is in contrast to point source pollution which results from a single source. nonpoint source pollution generally results from land runoff, precipitation, atmospheric deposition, drainage, seepage, or hydrological modification (rainfall and snowmelt) where tracing pollution back to a single source is difficult. nonpoint source water pollution affects a water body from sources such as polluted runoff from agricultural areas draining into a river, or wind-borne debris blowing out to sea. nonpoint source air pollution affects air quality, from sources such as smokestacks or car tailpipes. although these pollutants have originated from a point source, the long-range transport ability and multiple sources of the pollutant make it a nonpoint source of pollution; if the discharges were to occur to a body of water or into the atmosphere at a single location, the pollution would be single-point. part of a series onpollutionmuddy river polluted by sediment air acid rain air quality index atmospheric dispersion modeling chlorofluorocarbon exhaust gas haze indoor air internal combustion engine global dimming global distillation ozone depletion particulates persistent organic pollutant smog aerosol soot volatile organic compound biological biological hazard genetic introduced species (invasive species) digital information electromagnetic light ecological overillumination radio spectrum natural ozone radium and radon in the environment volcanic ash wildfire noise transportation land water air rail sustainable transport urban sonar marine mammals and sonar industrial military abstract noise control radiation actinides bioremediation depleted uranium nuclear fission nuclear fallout plutonium poisoning radioactivity uranium electromagnetic radiation and health radioactive waste soil agricultural herbicides manure waste pesticides land degradation bioremediation defecation electrical resistance heating soil guideline values phytoremediation solid waste biodegradable waste brown waste electronic waste battery recycling food waste green waste hazardous waste biomedical waste chemical waste construction waste lead poisoning mercury poisoning toxic waste international waste industrial waste lead smelting litter mining coal mining gold mining surface mining deep sea mining mining waste uranium mining municipal solid waste garbage nanomaterials plastic microplastics packaging waste post-consumer waste waste management landfill thermal treatment space satellite thermal urban heat island visual air travel advertising clutter overhead power lines traffic signs vandalism war chemical warfare herbicidal warfare (agent orange) nuclear holocaust (nuclear fallout - nuclear famine - nuclear winter) scorched earth unexploded ordnance war and environmental law water agricultural wastewater diseases eutrophication firewater freshwater groundwater hypoxia industrial wastewater marine debris monitoring nonpoint source see misc section nutrient ocean acidification oil spill pharmaceuticals freshwater salinization septic tanks sewage septic tanks pit latrine shipping stagnation sulfur water surface runoff turbidity urban runoff water quality misc point source area source legacy pollution lists diseases law by country most polluted cities least polluted cities by pm2.5 treaties categories by country environment portal ecology portal nonpoint source water pollution may derive from many different sources with no specific solutions or changes to rectify the problem, making it difficult to regulate. nonpoint source water pollution is difficult to control because it comes from the everyday activities of many different people, such as lawn fertilization, applying pesticides, road construction or building construction. controlling nonpoint source pollution requires improving the management of urban and suburban areas, agricultural operations, forestry operations and marinas. types of nonpoint source water pollution include sediment, nutrients, toxic contaminants and chemicals and pathogens. principal sources of nonpoint source water pollution include: urban and suburban areas, agricultural operations, atmospheric inputs, highway runoff, forestry and mining operations, marinas and boating activities. in urban areas, contaminated storm water washed off of parking lots, roads and highways, called urban runoff, is usually included under the category of non-point sources (it can become a point source if it is channeled into storm drain systems and discharged through pipes to local surface waters). in agriculture, the leaching out of nitrogen compounds from fertilized agricultural lands is a nonpoint source water pollution. nutrient runoff in storm water from "sheet flow" over an agricultural field or a forest are also examples of non-point source pollution. principal types (for water pollution) sediment runoff of soil and fertilizer during a rain storm characteristics of point and nonpoint sources of chemical inputs (modified from novonty and olem 1994) point sources wastewater effluent (municipal and industrial) runoff and leachate from waste disposal systems runoff and infiltration from animal feedlots runoff from mines, oil fields, unsewered industrial sites overflows of combined storm and sanitary sewers runoff from construction sites less than 20,000 m2 (220,000 ft²) untreated sewage nonpoint sources runoff from agriculture due to fertilizers and pesticides /irrigation runoff from pasture and range urban runoff from unsewered areas septic tank leachate runoff from construction sites >20,000 m2 (220,000 ft²) runoff from abandoned mines atmospheric deposition over a water surface other land activities generating contaminants sediment (loose soil) includes silt (fine particles) and suspended solids (larger particles). sediment may enter surface waters from eroding stream banks, and from surface runoff due to improper plant cover on urban and rural land. sediment creates turbidity (cloudiness) in water bodies, reducing the amount of light reaching lower depths, which can inhibit growth of submerged aquatic plants and consequently affect species which are dependent on them, such as fish and shellfish. high turbidity levels also inhibit drinking water purification systems. sediment can also be discharged from multiple different sources. sources include construction sites (although these are point sources, which can be managed with erosion controls and sediment controls), agricultural fields, stream banks, and highly disturbed areas. nutrients nonpoint source pollution is caused when precipitation (1) carries pollutants from the ground such as nitrogen (n) and phosphorus (p) pollutants which come from fertilizers used on farm lands (2) or urban areas (3). these nutrients can cause eutrophication (4). nutrients mainly refers to inorganic matter from runoff, landfills, livestock operations and crop lands. the two primary nutrients of concern are phosphorus and nitrogen. phosphorus is a nutrient that occurs in many forms that are bioavailable. it is notoriously over-abundant in human sewage sludge. it is a main ingredient in many fertilizers used for agriculture as well as on residential and commercial properties, and may become a limiting nutrient in freshwater systems and some estuaries. phosphorus is most often transported to water bodies via soil erosion because many forms of phosphorus tend to be adsorbed on to soil particles. excess amounts of phosphorus in aquatic systems (particularly freshwater lakes, reservoirs, and ponds) leads to proliferation of microscopic algae called phytoplankton. the increase of organic matter supply due to the excessive growth of the phytoplankton is called eutrophication. a common symptom of eutrophication is algae blooms that can produce unsightly surface scums, shade out beneficial types of plants, produce taste-and-odor-causing compounds, and poison the water due to toxins produced by the algae. these toxins are a particular problem in systems used for drinking water because some toxins can cause human illness and removal of the toxins is difficult and expensive. bacterial decomposition of algal blooms consumes dissolved oxygen in the water, generating hypoxia with detrimental consequences for fish and aquatic invertebrates. nitrogen is the other key ingredient in fertilizers, and it generally becomes a pollutant in saltwater or brackish estuarine systems where nitrogen is a limiting nutrient. similar to phosphorus in fresh-waters, excess amounts of bioavailable nitrogen in marine systems lead to eutrophication and algae blooms. hypoxia is an increasingly common result of eutrophication in marine systems and can impact large areas of estuaries, bays, and near shore coastal waters. each summer, hypoxic conditions form in bottom waters where the mississippi river enters the gulf of mexico. during recent summers, the aerial extent of this "dead zone" is comparable to the area of new jersey and has major detrimental consequences for fisheries in the region. nitrogen is most often transported by water as nitrate (no3). the nitrogen is usually added to a watershed as organic-n or ammonia (nh3), so nitrogen stays attached to the soil until oxidation converts it into nitrate. since the nitrate is generally already incorporated into the soil, the water traveling through the soil (i.e., interflow and tile drainage) is the most likely to transport it, rather than surface runoff. toxic contaminants and chemicals compounds including heavy metals like lead, mercury, zinc, and cadmium, organics like polychlorinated biphenyls (pcbs) and polycyclic aromatic hydrocarbons (pahs), fire retardants, and other substances are resistant to breakdown. these contaminants can come from a variety of sources including human sewage sludge, mining operations, vehicle emissions, fossil fuel combustion, urban runoff, industrial operations and landfills. toxic chemicals mainly include organic compounds and inorganic compounds. these compounds include pesticides like ddt, acids, and salts that have severe effects to the ecosystem and water-bodies. these compounds can threaten the health of both humans and aquatic species while being resistant to environmental breakdown, thus allowing them to persist in the environment. these toxic chemicals could come from croplands, nurseries, orchards, building sites, gardens, lawns and landfills. acids and salts mainly are inorganic pollutants from irrigated lands, mining operations, urban runoff, industrial sites and landfills. pathogens pathogens are bacteria and viruses that can be found in water and cause diseases in humans. typically, pathogens cause disease when they are present in public drinking water supplies. pathogens found in contaminated runoff may include: cryptosporidium parvum giardia lamblia salmonella norovirus and other viruses parasitic worms (helminths). coliform bacteria and fecal matter may also be detected in runoff. these bacteria are a commonly used indicator of water pollution, but not an actual cause of disease. pathogens may contaminate runoff due to poorly managed livestock operations, faulty septic systems, improper handling of pet waste, the over application of human sewage sludge, contaminated storm sewers, and sanitary sewer overflows. principal sources (for water pollution) urban and suburban areas urban and suburban areas are a main sources of nonpoint source pollution due to the amount of runoff that is produced due to the large amount of paved surfaces. paved surfaces, such as asphalt and concrete are impervious to water penetrating them. any water that is on contact with these surfaces will run off and be absorbed by the surrounding environment. these surfaces make it easier for stormwater to carry pollutants into the surrounding soil. construction sites tend to have disturbed soil that is easily eroded by precipitation like rain, snow, and hail. additionally, discarded debris on the site can be carried away by runoff waters and enter the aquatic environment. contaminated stormwater washed off parking lots, roads and highways, and lawns (often containing fertilizers and pesticides) is called urban runoff. this runoff is often classified as a type of nps pollution. some people may also consider it a point source because many times it is channeled into municipal storm drain systems and discharged through pipes to nearby surface waters. however, not all urban runoff flows through storm drain systems before entering water bodies. some may flow directly into water bodies, especially in developing and suburban areas. also, unlike other types of point sources, such as industrial discharges, sewage treatment plants and other operations, pollution in urban runoff cannot be attributed to one activity or even group of activities. therefore, because it is not caused by an easily identified and regulated activity, urban runoff pollution sources are also often treated as true nonpoint sources as municipalities work to abate them. typically, in suburban areas, chemicals are used for lawn care. these chemicals can end up in runoff and enter the surrounding environment via storm drains in the city. since the water in storm drains is not treated before flowing into surrounding water bodies, the chemicals enter the water directly. other significant sources of runoff include habitat modification and silviculture (forestry). agricultural operations nutrients (nitrogen and phosphorus) are typically applied to farmland as commercial fertilizer, animal manure, or spraying of municipal or industrial wastewater (effluent) or sludge. nutrients may also enter runoff from crop residues, irrigation water, wildlife, and atmospheric deposition.: p. 2–9 sediment (loose soil) washed off fields is a form of agricultural pollution. farms with large livestock and poultry operations, such as factory farms, are often point source dischargers. these facilities are called "concentrated animal feeding operations" or "feedlots" in the us and are being subject to increasing