Water Pollution
These include water quality standards; pollution discharge permits; mandatory best practices; environmental impact assessments for certain farming activities; buffer zones around farms; restrictions on agricultural practices or the location of farms; and limits on the marketing and sale of dangerous products.
However, the report acknowledges that well-known principles for reducing pollution, such as‘ polluter pays,’ are hard to apply to non-point agricultural pollution because identifying the actual polluters is neither easy nor cheap.
That means that measures that promote farmer“ buy in” are critical to preening pollution at the source— such as tax breaks for the adoption of practices that minimize farm export of nutrients and pesticides or payments to for“ landscape maintenance.”
On the farm, a number of best practices can reduce the export of pollutants into surrounding ecosystems, for example: minimizing the use of fertilizers and pesticides, establishing buffer zones along watercourses and farm boundaries, or improving drainage control schemes.
Integrated pest management, which combines the strategic use of pest-resistant crop varieties with crop rotation and the introduction of natural predators of common pests is another helpful tool
On livestock operations, traditional techniques such as restoring degraded pasturelands and better managing animal diets, feed additives and medicines are needed— while more also needs to be done with new nutrient recycling techniques and technologies, such as farm waste biodigesters.
Agricultural water pollution: Numbers of note
• Irrigation is the world’ s largest producer in volume of wastewater( in the form of agricultural drainage).
• Globally, around 115 million tonnes of mineral nitrogen fertilizers are applied to croplands each year. Around 20 percent of these nitrogen inputs end up accumulating in soils and biomass, whereas 35 percent enters the oceans.
• Worldwide, 4.6 million tonnes of chemical pesticides are sprayed into the environment every year.
• Developing countries account for 25 percent of world pesticide use in farming, but 99 percent of the world’ s deaths due to pesticides.
• Recent estimates that the economic impact of pesticides on non-target species( including humans) is approximately $ 8 billion annually in developing countries.
• Oxygen-depletion( hypoxia) resulting from manmade nutrient overloading affects an area of 240 000 km2 globally, comprising 70 000 km2 of inland waters and 170 000 km2 of coastal areas
• Worldwide, an estimated 24 percent of the area under irrigation is affected by salinization
• Currently, more than 700 emerging pollutants, their metabolites and transformation products, are listed as being present in the European aquatic environment.
Some Common Types of Water Contamination
Sewage and wastewater
Used water is wastewater. It comes from our sinks, showers, and toilets( think sewage) and from commercial, industrial, and agricultural activities( think metals, solvents, and toxic sludge). The term also includes stormwater runoff, which occurs when rainfall carries road salts, oil, grease, chemicals, and debris from impermeable surfaces into our waterways
More than 80 percent of the world’ s wastewater flows back into the environment without being treated or reused, according to the United Nations; in some least-developed countries, the figure tops 95 percent. In the United States, wastewater treatment facilities process about 34 billion gallons of wastewater per day. These facilities reduce the amount of pollutants such as pathogens, phosphorus, and nitrogen in sewage, as well as heavy metals and toxic chemicals in industrial waste, before discharging the treated waters back into waterways. That’ s when all goes well. But according to EPA estimates, our nation’ s aging and easily overwhelmed sewage treatment systems also release more than 850 billion gallons of untreated wastewater each year.
Oil pollution
Big spills may dominate headlines, but consumers account for the vast majority of oil pollution in our seas, including oil and gasoline that drips from millions of cars and trucks every day. Moreover, nearly half of the estimated 1 million tons of oil that makes its way into marine environments each year comes not from tanker spills but from land-based sources such as factories, farms, and cities. At sea, tanker spills account for about 10 percent of the oil in waters around the world, while regular operations of the shipping industry— through both legal and illegal discharges— contribute about one-third. Oil is also naturally released from under the ocean floor through fractures known as seeps.
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