Figure 21.17: Industrial Waste Water: Polluted water coming from a factory in Mexico. The
different colors of foam indicate various chemicals in the water and industrial pollution. ( 17 )
uses.- Other chemicals in industrial waste, such as heavy metals, organic toxins, oils, and
solids. - Chemical waste from burning high sulfur fossil fuels that cause acid rain.
- Inadequately treated or untreated sewage and solid wastes from inappropriate waste
disposal. - Oil and other petroleum products from supertanker spills and offshore drilling acci-
dents. - Heated water from industrial processes such as power stations.
Agricultural Pollution
Agriculture includes crops, livestock and poultry farming. Most agricultural contaminants
are carried by runoff that carries fertilizers, pesticides, and animal waste into nearby water-
ways (Figure21.18). Soil and silt erosion also contribute to surface water contamination.
Animal wastes expose humans and the environment to some of the most harmful disease
causing organisms or pathogens. These include bacteria, viruses, protozoa, and parasites.
Pathogens are especially harmful to humans, because they can cause many illnesses including
typhoid and dysentery as well as minor respiratory and skin diseases.
You may be surprised to learn that even the fertilizers we use on our lawns and farm fields
are extremely harmful to the environment. Fertilizers from lawns and farm fields wash into