Sources of Pollution

Water pollution can come from a multitude of sources; these tend to fall into the categories of agricultural waste, domestic waste, and industrial waste. All three types of waste have different effects on the environment and on humans. In order to protect ones self these effects need to be known so humans can take the necessary precautions in order to protect themselves.

The three main sources of water pollution consist of industry, agriculture, and human waste. In the United States, “industry accounts for more than half the volume of all water pollution and for the most deadly pollutants”. Industry contaminates water through the waste and byproducts it creates. Pollutants such as heavy metals, phosphates, and sulfates can be attributed to industrial factories. These factories use fresh water to carry waste away into streams, lakes, oceans, and other bodies of water; furthering the dispersion of the waste. Since industrial waste is directly injected into the bodies of water, it is considered a point source pollutant. Agriculture pollutes the water with the use of fertilizers, pesticides, and other chemicals through run off. The chemicals used by farmers will often stay in the soil and on the land for many years, and when it rains the chemicals are swept away by the rain and drained into fresh bodies of water. Because there are many sources of pollution from agricultural, it is deemed as a non-point source pollutant. Municipal waste is a large contributor to water pollution as well. Human waste pollution comes after the filtration and cleansing of sewage, after this process the excess sludge and chemicals are dumped, they then seep into the top soil and eventually find their way into a well or other bodies of water. As the population consistently grows, the municipal waste increases exponentially. This is a non point source pollutant since the pollution occurs when the sludge from the waste filtration is placed in the earth not directly into the water.

Water pollution from agricultural waste, like industrial farms, results from storage and disposal of animal waste. Industrial farms store their animal waste and other farm wastes in huge tanks called lagoons, but these tanks can often leak, which causes environmental damage that can be 160 times as damaging as raw sewage. Fertilizers are also used in industrial farms and causes agricultural waste. Phosphorous and nitrogen are minerals that fertilizers contain, too much of this can cause algal bloom, which is when there is a rapid increase of algae in an environment, which kills fish. Livestock manure is used in these industrial farms and contains high concentrations of ammonia. Dissolved ammonia is highly toxic to fish and can also be converted to dangerous nitrates. Elevated nitrate levels in drinking water are highly toxic to humans. Lastly antibiotics and artificial growth hormones are also used in industrial farms. Large amounts of both substances end up being excreted by animals and can thus pollute water along with everything else in livestock waste. Some hormones can remain functional in manure up to 270 days after excretion, and there have been many documented cases of hormones discovered miles downstream of farms.

Industrial waste is due to the runoff sewage released into water supplies from factories, mining sights, or other industrial areas. This type of waste contains numerous pollutants. Some examples of industrial waste water pollution are lead, mercury, nitrates, phosphates, sulfur, oils, and petro chemicals. Lead and mercury are metallic elements that can cause health and environmental problems as well. They are non-biodegradable substances so it is hard to clean them up once they contaminate an environment. Lead can inhibit the action of bodily enzymes while mercury can cause illness through mercury poisoning. The increased use of fertilizers means that phosphates are more often being washed from the soil and into rivers and lakes. This can cause eutrophication, an abundant accumulation of nutrients that support a dense growth of algae and other organisms, the decay of which depletes the shallow waters of oxygen in summer. Sulfur is a non-metallic substance that is also harmful for marine life. Another contaminate is oil which does not dissolve in water; instead it forms a thick layer on the waters surface. This can stop marine plants receiving enough light for photosynthesis. It is also harmful for fish and marine birds because they swim or fly into the oil and become coated in it. Oil can clog the gills of a fish and prevent birds from flying. Lastly petrochemicals are formed from gas or petrol and can also be toxic to marine life.

The City of Tianjin is China’s third largest industrial city and for years it has caused many environmental problems due to the fact that the construction of urban drainage, sewage, and wastewater treatment are far behind the environmental requirements for the city. This has caused the farmers to use untreated wastewater for drinking and agricultural purposes. Also, the industrial plants located in the City of Tianjin have managed to contaminate one of China’s five largest freshwater lakes, Chao Lake. This lake is used to supply water to the surrounding provinces but with the large industrial waste polluting it less and less water can be used from the lake. Recently a wastewater improvement project has been proposed and co-financed by the Tianjin Municipal Government and the World Bank to improve the city’s water. This project will focus on the improvement of waste managements systems.

The various substances that we use for keeping our houses clean add to water pollution because they contain harmful chemicals. Most detergents and washing powders contain phosphates which are used to soften the water, among other things. These and other chemicals contained in washing powders affect the health of all forms of life in the water. When sewage enters a lake or stream, microorganisms begin to decompose the organic materials. Oxygen is consumed as micro-organisms use it in their metabolism. Sewage-contaminated water causes eutrophication, which is the increase in concentration of chemical elements required for life. The nitrates, phosphates, and organic matter found in human waste serve as a food for algae and bacteria. This causes these organisms to overpopulate to the point where they use up most of the dissolved oxygen that is naturally found in water, making it difficult for other organisms in their aquatic environment to live. The bacteria are basically strangling the other organisms. Some of the organisms that do overpopulate from this are also disease-causing microorganisms; these diseases are then spread to humans when they drink said water. Phosphates are also found in soaps and detergents, but there are other household products that we use every day that can be toxic to many animals and humans if they are dumped directly into a body of water. All of these harm both the environments they are introduced to and the humans who drink the water.

There are several ways to detect water pollution sources but one of the most common ways is to use a detecting tube for nitrite; nitrate monitoring was developed as a spot test. The detecting tube is prepared by the packing of poly(vinyl chloride) (PVC) particles coated with a quaternary ammonium salt into a mini-column. A nitrite solution is then treated with sulfanilic acid and 1-naphthol; the resultant colored solution is then drawn into the detecting tube by suction with a syringe, and a color band is formed in the tube. The color band length (CBL) corresponds to the nitrite concentration. Nitrate is also detected after reduction with zinc. The nitrite and nitrate content of domestic wastewater samples is successfully detected by this method over the range of 0.5–45.3 mg-N L⁻¹ as nitrogen concentration. Another type of detecting tube is prepared by alternately packing adsorbent and uncoated PVC particles in a mini-column. Colored zebra-bands are formed in this column, and the nitrite concentration is detected by counting the number of colored zebra-bands. Nitrite and nitrate concentrations in actual wastewater samples are detected more easily by this method, although the accuracy is somewhat lower than that obtained with the CBL method.

A chemical sensor array is used to continuously monitor for the presence or absence of industrial pollutants in the headspace of wastewater generated from an on-line flow-cell. A domestic wastewater is doused with diesel to stimulate the presence of an intermittent discharge in a wastewater influent. Response patterns between the sensors are used to detect for the presence of organic compounds in the wastewater. Correlations between the sensor response patterns or fingerprints are also analyzed using principal component analysis. The results clearly demonstrate that a chemical sensor array can rapidly identify the presence of organic compounds (such as diesel) in a wastewater matrix and could be further developed to monitor for industrial pollutants at the inlet of sewage works.