Other Issues in Water Pollution Urbanization General Population Growth Increased Run-off and Pollution Non-point Pollution Sources (eg Agriculture) Pesticide Use (Module 5) Toxic Organic Chemicals Industrial Effluents Organic Loading Wood burning for Fuel (eg East African lakes - Lake Victoria) Deforestation Microbiological Contamination (Module 4)

Some Observations: General Population Growth was for many years considered the single most important issue affecting actual and future water pollution. This has changed with changes in estimates of population growth rates. Since 1969 population has grown from 3.7 billion to 6 billion. But annual rates of population growth have slowed from 2.04 to 1.33 per cent, and should fall further. Annual additions peaked in at 86 million. They should fall gradually in the next 20 years and more rapidly thereafter.

This view now has changed to one that emphasizes Urbanization and population concentration in the larger cities – often on sea coasts Eleven of the world's 15 largest cities lie along the coast or on estuaries. In the United States, around 53% of the population lives near the coast New calculations show that percent of the world's population live within 100 kilometres of the coast (Cohen et al., 1997). Since the coastal 100 kilometre strip represents 18.7% of the total land area (27,491,108 km2 out of 146,874,796 km2), the average human population density in coastal areas is about 80 persons per square kilometre, twice the global average. Considering that many coastlines are sparsely populated or uninhabited (Antarctica, the far North, etc.), the actual population pressure on the coast in more habitable areas is very high l

Because more urbanized watersheds tend to have greater impervious areas as well as higher quantities of urban and industrial pollution, this map also shows greater pressure on freshwater systems. This map shows that highly urbanized watersheds are concentrated along the east coast of the United States, Western Europe, and Japan, with lesser concentrations in coastal China, India, Central America, most of the United States, Western Europe, and the Persian Gulf

This map shows the level of human modification of the coastal zone, by examining the population within 100 kilometres from the coast. As human population increases in coastal areas, so does pressure on coastal ecosystems through habitat conversion, increased pollution, and demand for coastal resources. The degree of direct human modification of coastal ecosystems can be inferred by looking at the population density within the coastal zone. Globally, the number of people living within 100 km of the coast increased from roughly 2 billion in 1990 to 2.2 billion in 1995—39 percent of the world's population.

Distribution of Renewable Water resources per capita: There is a rapid change from 1995 to 2025 in the availability of water resources …….

Data From: USGS National Water Quality Assessment and the Pesticide National Synthesis ProjectNational Water Quality Assessment and the Pesticide National Synthesis Project The concentration of population in the US around water bodies and the coastal regions is also apparent

The effects of the population and intensive farming in the areas of the US is also clear when examining the: deposition of nitrogen from the atmosphere (air pollution) non-point sources of nitrogen from animal manure application of nitrogen and phosphorus in fertilizers Population change and migration continues. Figures from the US show a marked migration from rural to urban areas (and a movement southwest and southeast)

These urban populations cause water pollution, but the rural populations (although decreasing) are required to increase food output for the increased population in urban areas. This has many ramifications; one of these is increased groundwater pollution and aquifer contamination due to intensive farming applications being done over vulnerable aquifers. Surface waters can also become contaminated from these acivities

Pesticides and their Distribution: Note in the following slides the distribution of different kinds of pesticides: Atrazine, Cyanazine and Paraquat are herbicides: Note the wide distribution in the Mid-West of Atrazine and Cyanazine – commonly used on corn crops. Paraquat is a total kill herbicide used for no-till agriculture and is also widely used in the Mid_west and California Chlorpyriphos is an insecticide: It is widely used in many crop-growing and vegetable/fruit growing areas 2,4-D is a selective herbicide: It is widely used in both the Mid-West and the western wheat areas as well as California Ethion is an insecticide: It is used in vegetable and fruit growing areas to control pests of those crops (Florida, California, etc.)

Deforestation

Other Issues in Water Pollution General Population Growth Urbanization Increased Run-off and Pollution Non-point Pollution Sources (eg Agriculture) Pesticide Use (Module 5) Toxic Organic Chemicals Industrial Effluents Organic Loading Wood burning for Fuel (eg East African lakes - Lake Victoria) Deforestation Microbiological Contamination (Module 4)