Water pollution cause by heavy metals

               

 Water pollution:

“Water pollution is the contamination of waterbodies, usually as a result of human activities. Water bodies include for example lakes, rivers, oceans, aquifers and groundwater”

Example:

For example, releasing inadequately treated wastewater into natural water bodies can lead to degradation of aquatic ecosystems.
Heavy metals

 Heavy metals are natural components of the Earth's crust.
 Have high densities.
 Toxic in nature.
 Non degradable.

 Heavy metals are dangerous because they tend to bio accumulate.
Sources:

 Heavy metals can enter a water supply by industrial and consumer waste,
 or even from acidic rain breaking down soils and releasing heavy metals into streams, lakes, rivers, and groundwater.

Heavy metals in Aquatic Environment:
The most common metal pollution in freshwater comes from mining companies. They usually use an acid mine drainage system to release heavy metals from ores, because metals are very soluble in an acid Solution.
Cigarette smoking is a major source of cadmium exposure

The most common heavy metal pollutants are
 Mercury
 Lead
 arsenic,
 cadmium
 Zinc

Mercury:

Natural sources:
 Volcanic eruptions.
 Rock weathering

Anthropogenic sources:
 Mercury mining
 Smelting
 Coal fire and burning fossil fuels

Effects:
 Damage of brain, Kidneys and Lungs.
 Irritation of nose, skin and also skin burns.
 Irritation of Respitatory System.
 Rashes

Environmental effects:

 Mercury in water is transformed into methyl mercury
 Minamata disease due to consumption of methyl mercury contaminated fish

Lead:
 General metabolic poison

Sources:

 Discharge from smelter
 Battery manufacture
 Lead is used in pipes i.e. PVC.

:
 Damage the central nervous system
 Loss IQ level in children
 Cardiovascular and renal diseases in adult

Environmental effects:
 Approximately 94% pb in the atmosphere derived from heavy motor.
 Lead combine with colloidal practical found in natural water.
 Urban run off cause of pollution surface and groundwater .consumption of such untreated water may lead to pb poisoning.

Arsenic:

Cumulative poison carcinogens
Sources:
 Pesticides and herbicides
 Metal smelters
 paints
 Arsenic may also be found in water supplies worldwide, leading to exposure of shellfish, cod, and haddock.

Effects:

 breathing problems
 death if exposed to high level.
 decreased intelligence
 known human carcinogen: lung and skin cancer
 nausea, diarrhea, vomiting
 peripheral nervous system problems
 Birth defects

Cadmium:

Cadmium is most toxic in their ionic forms.
Sources:
 Coal burning is the main source of environmental cadmium.
 Mine tailings
 Phosphate mining
 Electroplating wastes
 Fertilizers produced from Phosphate ores
 Cadmium is used as a pigment in paints.
 Cigarette smoke
 Cadmium is used as Fertilizers and pesticides.

Effects:

 DNA damage and cancer development
 Damage to the immune system
 Psychological disorders
 Reproductive failure
 Disease called Itai Itai caused by
cadmium

Environmental effects:
 Cadmium rich sludge can pollute surface waters as well as soils.
 Cadmium strongly adsorbs to organic matter in soil.
 In Aquatic ecosystems Cadmium can bio accumulate in fish.

Zinc:

Sources:
 Refineries
 Metal plating
 Brass manufacture

Effects:

 Nausea and Vomiting.
 Stomach Pain and Diarrhea. Typically, stomach pain and diarrhea occur in conjunction with nausea and vomiting.
 Flu-Like Symptoms.
 Changes in Your Taste.
 Frequent Infections
 Copper Deficiency. .

Environmental effects:

 Zinc salts cause a milky turbidity in water in higher concentrations.
 Additionally, zinc may add an unwanted flavour to water.
 This occurs at concentrations of about 2 mg Zn2+/ L.


Control:
 Heavy metals can be removed by using Aluminum-based coagulants.
 Heavy metals can be removed from waste water by the method adsorption.
 The metal contaminant gets adsorbed to the surface of the adsorbents i.e ( the medium ) and gets removed.
 Activated Carbon can be used as adsorbent for removing heavy metals.