Water Pollution
The
agent that causes the pollution is called pollutants. Any condition to
environment components that threatens the health survival and activities of
humans or other living organisms is called pollution.
Water
pollution is a major global problem. 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. In the most recent national report on
water quality in the United States, 45 percent of assessed stream miles, 47
percent of assessed lake acres, and 32 percent of assessed bay and estuarine
square miles were classified as polluted.
What is Water Pollution?
Water
pollution is the contamination of water bodies (e.g. lakes, rivers, oceans and
groundwater). Water pollution occurs when pollutants are discharged directly or
indirectly into water bodies without adequate treatment to remove harmful
compounds. Or the presence of extraneous materials in the water in sufficient
quantities and durations to cause harm us, other forms of life and materials
change in water quality and ecosystem is called water pollution.
Water
pollution affects plants and organisms living in these bodies of water; and, in
almost all cases the effect is damaging not only to individual species and
populations, but also to the natural biological communities.
Any
chemicals, physical, biological change in water quality that has a harmful
effect on living organisms and makes water unsuitable for desired uses is
called polluted water.
Sources of water pollution:
·
Point sources
·
Non-point sources
1) Point sources
Pollutants
discharge from one sources. A point source of pollution is a single
identifiable localized source of water pollution. It involves discharge from
factories, sewage system, power plants, underground coal mines, and oil wells.
These sources are easy to identify and therefore easy to monitor and regulate
than nonpoint sources. A point source has negligible extent, distinguishing it
from other pollution source geometries Water pollution from an oil refinery
wastewater discharge outlets. In developing countries such discharges are
largely uncontrolled.
2) Non-point
sources
Non–point
source pollution refers to diffuse contamination that does not originate from a
single discrete source. Non-point sources are those sources that can’t be
traced to any single site of discharge. They occurs usually large lands. Some
of the most prominent nonpoint sources of water pollution are agricultural
runoff from cropland and animal farm, storm water from drainage from street and
parking lot and from atmospheric deposition little process have been made in
controlling non-point sources of water pollution because of the difficulty and
expense of identifying and controlling discharge from so many diffused sources.
Two
basic strategies are employed in attempting to bring water pollution under
control:
1. Reduce
or remove the sources (best)
2. Treat
water (wastewater treatment)
Some
of the water pollutants are discussed below:-
1) Pathogens:
The most serious and widespread water pollutants are the infectious agents that
cause sickness and death. Pathogens are the diseases causing bacteria, viruses
and other parasite organisms that grow and multiply within the host. The
excrement from humans and other animals infected with certain pathogens
contains large number of these organisms and contaminated water is responsible
for the spread of many contagious diseases.
Public
health—Sanitation = Good medicine
2) Organic
Wastes: Along with the pathogens human and animal wastes contain organic matter
that creates serious problems if it enters bodies of water untreated. Other
kind of organic matter like leaves, grass, clippings, trash and so forth. This
wastes are biodegradable. The amount of oxygen that water can hold in solution
in severely limited when bacteria and detritus feeders decompose organic matter
in water, they compose oxygen gas dissolved in the water. In cold water do not
reach up to 10 ppm much less can be held in warm water. Oxygen demanding wastes
are substances that at oxidise in the receiving body of water. Oxygen demanding
wastes threatens the aquatic life.
BOD:
Biochemical oxygen demand is a measure of the amount of organic material in
water, stated in terms of how much oxygen will be required to break it down
biologically, chemically or both
3) Chemical
Pollutants
Water
is the excellent universal solvent, have ability to hold many chemicals
substances in solution that have undesirable effects. Water soluble inorganic
chemicals constitute an important class of pollutants that include heavy metals
like lead, mercury, arsenic, nickel and so forth. Acids from mine drainage and
salt.
Organic
chemicals:
·
Hydrocarbons
·
Petroleum products
·
Detergents and soap
·
Cleaning solvents
·
Pesticides
These chemical pollutants are toxic in even small amount which is
dangerous for humans, aquatic and ecosystem.
4) Nutrients:
They are essential elements
required by plants and other living things. Some of the in organic chemicals
carried in solutions in all bodies of water called nutrients. Nitrogen,
phosphorus, carbon, sulphur, calcium, potassium, iron, manganese, boron and
cobalt al are required by living things.
Nutrients can be considered as pollutants when their concentration are
sufficient to allow excessive growth of aquatic plants.. Suitably treated and
used in moderate quantities, sewage can be a fertilizer: it returns important
nutrients to the environment, such as nitrogen and phosphorus, which plants and
animals need for growth. The trouble is, sewage is often released in much
greater quantities than the natural environment can cope with. Chemical
fertilizers used by farmers also add nutrients to the soil, which drain into
rivers and seas and add to the fertilizing effect of the sewage. Together,
sewage and fertilizers can cause a massive increase in the growth of algae or
plankton that overwhelms huge areas of oceans, lakes, or rivers. Especially
algae because of the nutrient enrichment algal bloom takes place. Algae and
decaying organic matter add colour turbidity, odours and objectionable tastes
to water that are difficult to remove and that may greatly reduce its
acceptability as a domestic water source. The process of nutrient enrichment is
called eutrophication. This is known as a harmful algal bloom it can turn the
water red. It is harmful because it removes oxygen from the water that kills
other forms of life, leading to what is known as a dead zone.
5) Thermal
pollution:
A
large stream-electric power plant requires an enormous amount of cooling water.
If that heat release in water, resulting temperature can adversely affect life
in the vicinity of the thermal plume. When temperatures increases metabolism
rate of microorganisms also increases and dissolved oxygen level decreases by
2-3 ppm.
6) Sediments:
As
natural landforms weather, especially during streams, a certain amount of
sediments enters streams and rivers. Erosion, deforestation, overgrazing
uncontrolled agriculture are main cause of the huge amount of soil loss.
Sediments have direct and extreme physical impacts on streams and rivers.
(Sand, silt and clay)
7) Radioactive
Waste:
People
view radioactive waste with great alarm—and for good reason. At high enough
concentrations it can kill; in lower concentrations it can cause cancers and
other illnesses. The biggest sources of radioactive pollution in Europe are two
factories that reprocess waste fuel from nuclear power plants.
Water quality
criteria and standard:
When water is
considered polluted?
The
Quality of water is of vital concern for mankind since it is directly linked
with human welfare. Not only should human being the water quality be maintained
for all living beings and planet earth to maintain proper cycling of planet.
EPA
of US listed 167 chemicals and substances as criteria pollutants. The majority
of these toxic chemicals but mainly are also natural chemicals or conditions
that describe the state of water such as nutrients, hardness, acidity, etc.
Drinking water standard are sticker than other water quality standard. It cover
some 94 chemical substances as contaminants.
|
Parameters
|
USPH Standard
|
|
Color, odour, taste
|
Less
|
|
PH
|
6-8
|
|
Dissolved oxygen
|
4-6 ppm
|
|
Chemical oxygen demand
|
4 ppm
|
|
Total bacteria count
|
100000
|
|
Suspended solid
|
5
|
|
Chloride, sulfate
|
250 ppm
|
|
Cyanide
|
0.05 ppm
|
|
Nitrate+ nitrite
|
<10
|
|
Arsenic
|
0.05
|
|
Calcium
|
100
|
|
Magnesium
|
30
|
|
Barium
|
1
|
|
Cadmium
|
0.01
|
|
Copper
|
1
|
|
Iron
|
<0.3
|
|
Lead
|
<0.05
|
|
Mercury
|
0.001
|
|
Silver
|
0.05
|
|
Zinc
|
5.5
|
|
manganese
|
<0.05
|
The
socioeconomic structure/condition, population growth, mismanagement, climate
change etc. are the major threats to the sources of the water.
We
the human being are responsible for it and we can fix the problem if we start
to change behaviour from now .
.JPG)
Photo-Mahabouddha,Kathmandu
photo-KhullaManch ,Kathmandu
Photo-ideal
urban forest