موضوع بالانجليزي عن تلوث المياه
Water pollution is the contamination of water bodies such as lakes, rivers, oceans, and groundwater
caused by human activities, which can be harmful to organisms and plants which live in
these water bodies.
Although natural phenomena such as volcanoes, algae blooms, storms, and earthquakes also cause major changes
in water quality and the ecological status of water, water is typically referred to as
polluted when it impaired by anthropogenic contaminants and either does not support a human use
(like serving as drinking water) or undergoes a marked shift in its ability to support
its constituent biotic communities. Water pollution has many causes and characteristics. The primary sources of
water pollution are generally grouped into two categories based on their point of origin. Point-source
pollution refers to contaminants that enter a waterway through a discrete “point source”.
Examples of this category include discharges from a wastewater treatment plant, outfalls from a factory,
leaking underground tanks, etc. The second primary category, non-point source pollution, refers to contamination that,
as its name suggests, does not originate from a single discrete source. Non-point source pollution
is often a cumulative effect of small amounts of contaminants gathered from a large area.
Nutrient runoff in storm water from sheet flow over an agricultural field, or $$$$ls and
hydrocarbons from an area with high impervious surfaces and vehicular traffic are examples of non-point
source pollution. The primary focus of legislation and efforts to curb water pollution for the
past several decades was first aimed at point sources. As point sources have been effectively
regulated, greater attention has come to be placed on non-point source contributions, especially in rapidly
urbanizing/suburbanizing or developing areas….
The specific contaminants leading to pollution in water include a wide spectrum of chemicals, pathogens,
and physical or sensory changes. While many of the chemicals and substances that are regulated
may be naturally occurring (iron, manganese, etc) the concentration is often the key in determining
what is a natural component of water, and what is a contaminant. Many of the
chemical substances are toxic. Pathogens can produce waterborne diseases in either human or animal hosts.
Alteration of water’s physical chemistry include acidity, electrical conductivity, temperature, and eutrophication. Eutrophication is the
fertilization of surface water by nutrients that were previously scarce. Water pollution is a major
problem in the global con$$$$. It has been suggested that it is the leading worldwide
cause of deaths and diseases, and that it accounts for the deaths of more than
14,000 people daily.
