Marine pollution
#environment
✅Oceans are the ultimate sink of all natural and manmade pollutants.
✅The sewerage and garbage of coastal cities are also dumped into the sea.
✅The other sources of oceanic pollution are navigational discharge of oil, grease, detergents, sewage, garbage and radioactive wastes, offshore oil mining, oil spills.
Oil Spills
✅The most common cause of oil spill is leakage during marine transport and leakage from underground storage tanks.
✅An oil spill could occur during offshore oil production as well.
Impact of oil spill on marine life
✅Oil being lighter than water covers the water surface as a thin film cutting off oxygen to floating plants and other producers.
✅Within hours of an oil spill, the fishes, shellfish, plankton die due to suffocation and metabolic disorders.
Birds and sea mammals that consume dead fishes and plankton die due to poisoning.
Effects of Water Pollution on Human Health
✅Domestic and hospital sewage contain many undesirable pathogenic microorganisms, and its disposal into water without proper treatment may cause an outbreak of serious diseases, such as typhoid, cholera, etc.
✅Metals like lead, zinc, arsenic, copper, mercury and cadmium in industrial wastewaters adversely affect humans and other animals.
✅Consumption of such arsenic polluted water leads to accumulation of arsenic in the body parts like blood, nails and hairs causing skin lesions, rough skin, dry and thickening of the skin and ultimately skin cancer.
✅Mercury compounds in wastewater are converted by bacterial action into extremely toxic methyl mercury, which can cause numbness of limbs, lips and tongue, deafness, blurring of vision and mental derangement.
✅Pollution of water bodies by mercury causes Minamata (neurological syndrome) disease in humans.
✅Lead causes lead poisoning (Lead interferes with a variety of body processes and is toxic to many organs and tissues).
✅The compounds of lead cause anaemia, headache, loss of muscle power and bluish line around the gum.
Effects of Water Pollution on the Environment
✅Micro-organisms involved in biodegradation of organic matter in sewage waste consume a lot of oxygen and make water oxygen deficient killing fish and other aquatic creatures.
✅Presence of large amounts of nutrients in water results in algal bloom (excessive growth of planktonic algae. This leads to ageing of lakes.
✅A few toxic substances, often present in industrial wastewaters, can undergo biological magnification (Biomagnification) in the aquatic food chain. This phenomenon is well-known for mercury and DDT.
✅High concentrations of DDT disturb calcium metabolism in birds, which causes thinning of eggshell and their premature breaking, eventually causing a decline in bird populations.
Eutrophication
✅Lakes receive their water from surface runoff and along with its various chemical substances and minerals.
✅Over periods spanning millennia, ageing occurs as the lakes accumulate mineral and organic matter and gradually, get filled up.
✅The nutrient-enrichment of the lakes promotes the growth of algae, aquatic plants and various fauna. This process is known as natural eutrophication.
✅Similar nutrient enrichment of lakes at an accelerated rate is caused by human activities and the consequent ageing phenomenon is known as cultural eutrophication.
✅On the basis of their nutrient content, lakes are categorized as Oligotrophic (very low nutrients), Mesotrophic (moderate nutrients) and Eutrophic (highly nutrient rich).
✅A vast majority of lakes in India are either eutrophic or mesotrophic because of the nutrients derived from their surroundings or organic wastes entering them.
Eutrophication and Algal Bloom
✅Eutrophic water body: it is a body of water rich in nutrients and so supporting a dense plant population, the decomposition of which kills animal life by depriving it of oxygen.
✅Eutrophication is the response to the addition of nutrients such as nitrates and phosphates naturally or artificially, fertilising the aquatic ecosystem.
✅Phytoplankton (algae and blue-green bacteria) thrive on the excess nutrients and their population explosion covers almost entire surface layer. This condition is known as algal bloom.
Effects of Eutrophication
✅Loss of freshwater lakes: Eutrophication eventually creates detritus layer in lakes and produces successively shallower depth of surface water.
✅Eventually, the water body is reduced into marsh whose plant community is transformed from an aquatic environment to a recognizable terrestrial environment.
✅Algal Blooms restrict the penetration of sunlight resulting in the death of aquatic plants and hence restricts the replenishment of oxygen.
✅New species invasion: Eutrophication may cause the ecosystem competitive by transforming the normal limiting nutrient to abundant level. This cause shifting in species composition of the ecosystem.
✅Loss of coral reefs: Occurs due to decrease in water transparency (increased turbidity).
✅Affects navigation due to increased turbidity; creates colour (yellow, green, red), smell and water treatment problems; increases biomass of inedible toxic phytoplankton, benthic and epiphytic algae and bloom of gelatinous zooplankton.
Dead zones
✅Dead zones (biological deserts) are increasing in the coastal delta and estuarine regions.
✅Hypoxic zones (zones deprived of oxygen) can occur naturally (due to upwelling of nutrients).
✅They can be created or enhanced by human activity to form dead zones.
✅Dead zones are areas in the ocean with very low oxygen concentration (hypoxic conditions).
✅Dead zones emerge when influx of chemical nutrients spur algae growth.
✅These zones usually occur 200-800 meters (in the saltwater layer) below the surface.
✅Dead zones are detrimental to animal life. Most of the animal life either dies or migrates from the zone.
✅One of the largest dead zones forms in the Gulf of Mexico every spring (farmers fertilize their crops and rain washes fertilizer off the land and into streams and rivers).
Photo chemical scope
also known as summer smog, is a type of smog that is produced when UV light originating from the sun interacts with the oxides of nitrogen present in the atmosphere.
✅This type of smog usually manifests as a brown haze and is most commonly seen in highly populated cities that are placed in relatively warm climates.
✅photochemical smog is most prominently visible during the mornings and afternoons.
✅Photochemical form is formed by a complex series of chemical reactions involving sunlight, oxides of nitrogen, and volatile organic compounds that are present in the atmosphere as a result of air pollution. These reactions often result in the formation of ground level ozone and certain airborne particles. The formation of photochemical smog is closely related to the concentration of primary pollutants in the atmosphere.
✅It is also related to the concentration of secondary pollutants (in some cases).
