domingo, 27 de junio de 2010
Ocean Pollution
Ocean Pollution

Toxic pollutants in the ocean have considerable impacts on plants and animals. Heavy metal poisoning from elements such as lead and mercury, caused by industry, builds up in the tissues of top predators such as whales and sharks, causing birth defects and nervous system damage. Dioxins from pulp and paper mills, and poly-aromatic hydrocarbons (PAH's) from oil pollution and burning wood and coal cause genetic problems in marine animals. Polychlorinated biphenyls (PCB’s) from electrical equipment can cause birth problems in most marine organisms. Sewage can cause massive nutrient loading in the oceans, which leads to algal blooms, effectively decreasing the amount of dissolved oxygen in the water and many organisms die from lack of oxygen. Sewage also introduces parasites and bacteria, which can cause beach and shellfish harvesting closures.
Garbage has always been discarded into the ocean, but since the 1940s, plastic use has increased dramatically, resulting in a huge quantity of nearly indestructible, lightweight material floating in the oceans and eventually deposited on beaches worldwide. Marine garbage includes fishing nets, plastics, party balloons, beach toys, general household garbage. Animals eat this garbage and it strangles them or blocks their digestive system causing starvation. Entanglement can also constrict growth and circulation, causing eventual slow death, or trap marine animals within large debris, leading to drowning, starvation or attack by predators. Even if just attached, it slows the animals’ ability to move through the water, and animals starve due to their inability to catch prey.
Soil Contamination
Soil contamination- one of the most dangerous forms of contamination- is caused by the presence of xenobiotic (human-made) chemicals or other alteration in the natural soil environment. This type of contamination typically arises from the rupture of underground storage tanks, application of pesticides, percolation of contaminated surface water to subsurface strata, oil and fuel dumping, leaching of wastes from landfills or direct discharge of industrial wastes to the soil. The most common chemicals involved are petroleum hydrocarbons, solvents, pesticides, lead and other heavy metals. This occurrence of this phenomenon is correlated with the degree of industrialization and intensities of chemical usage.
The concern over soil contamination stems primarily from health risks, from direct contact with the contaminated soil, vapors from the contaminants, and from secondary contamination of water supplies within and underlying the soil. Mapping of contaminated soil sites and the resulting cleanup are time consuming and expensive tasks, requiring extensive amounts of geology, hydrology, chemistry and computer modeling skills.
It is in North America and Western Europe that the extent of contaminated land is most well known, with many of countries in these areas having a legal framework to identify and deal with this environmental problem; this however may well be just the tip of the iceberg with developing countries very likely to be the next generation of new soil contamination cases.
Most polluting cities in the world

- Linfen, China. Air and water pollution by particles and gases in the mining industry and food processing.
- Ranipet, India. Water and soil contamination by industrial chemicals for dyeing.
- Mailuu Suu, Kirjistán. Soil and water pollution by radioactive waste from uranium nuclear industry (Russia).
- Dzerzhinsky, Russia. Water and soil pollution by chemical weapons production.
- Norilsk, Russia. Pollution of air, soil and water with sulfur dioxide, cesium and other elements from the production of platinum.
- Rudnaya Pristan, Russia. Soil contamination from lead, derived from mining.
- Chernobyl in the Ukraine. Water and soil pollution by radioactive waste arising after the nuclear plant accident.
- Kabwe, Zambia. Soil contamination by lead, resulting from their mining.
- Oroya, Peru. Air and soil pollution by lead, resulting from their mining.
- Haina, Dominican Republic. Soil contamination from lead, derived from the recycling of batteries.

Air Contamination

martes, 22 de junio de 2010
Contamination in Ecuador
