26 Apr

Water Pollution Related Issues – 2

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Content

• Heavy Metal Pollution
• Marine Pollution

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1) HEAVY METAL POLLUTION

• ­Heavy Metals and their Health Impacts
  • Heavy Metals are metals with relatively high densities, atomic weights, and atomic numbers.
    • Some heavy metals are either essential nutrients (Iron, Cobalt, Zinc etc.) or relatively harmless (such as ruthenium, silver, indium etc.), but can be toxic in large amounts.
    • Other heavy metals like (Lead, Cadmium, Mercury, Chromium, Arsenic etc.) are highly poisonous.
      • Lead was the most common cause of heavy metal But with phasing out of leaded petrol all across the world, this would go down.
        • Lead poisoning may lead to damage to brain, nervous system, Kidney etc. It may also interfere with the development of RBCs
      • Mercury – covered separately in
      • Cadmium – Industrial waste, batteries etc. are the most important source of cadmium poisoning. It negatively hampers the heart condition. It may also cause cancer and organ system toxicity such as skeletal, urinary, reproductive, cardiovascular etc.
  • Long term exposure to heavy metals may result in slowly progressing physical, muscular, and neurological degenerative process.
  • Once dispersed in the biosphere, these metals cannot be recovered or degraded. Hence, environmental effects of metal pollution tend to be permanent.
• Sources of Heavy Metal Poisoning:
  • Mining
    • For g. mining releases chromium, cadmium, lead and mercury – all toxic heavy metals.
    • Raniganj in West Bengal, Jharia in Bihar and Singrauli in Madhya Pradesh are considered some of the “hot spots” of metal pollution.
  • Tailings
  • Industrial Waste
  • Agricultural runoffs
  • Occupational exposures
  • Paints
  • Treated Timber

A) LEAD POISONING

• ­Lead:
  • It is a naturally occurring toxic metal found in the Earth’s crust. Its widespread use has resulted in extensive environmental contamination, human exposure and significant public health problems in many parts of the world.
  • There is no safe level of lead in the body.
    • Mental impairment can occur due to the presence of five micrograms of lead per deciliter (mcg/dL) of blood. Levels in excess of 100 mCg/dL can be fatal.
  • Where is lead used?
    • More than 3/4th of the global lead consumption happens in manufacture of lead acid batteries for motor vehicles.
    • It is also used in products like pigments, paints, solder, stained glass, lead crystal glassware, ammunition, ceramic glazes, jewellery, toys and some cosmetics and traditional medicines.
  • Important sources of environmental contamination:
    • Mining
    • Smelting
    • Manufacturing
    • Recycling activities
    • Use of leaded paint and leaded aviation fuel
    • Drinking water – delivered through lead pipes or pipes joined with lead solder may contain lead.
  • Much of the global use of lead is now obtained through recycling.
• Health Issues:
  • Young children are particularly vulnerable to the toxic effects of lead. It also causes long-term harm in adult, including increased risk of high blood pressure and kidney damage.
  • Pregnant women, if exposed to high level of lead, may suffer from miscarriage, stillbirth, premature birth or low birth weight.
• Sources and routes of exposure:
  • Inhalation of lead particles generated by burning materials containing lead for e.g. during smelting, recycling, stripping etc.
  • Ingestion of lead contaminated dust, water (from leaded pipes) and food (from lead-glazed or lead soldered containers).
  • Some traditional medicines (in India, Mexico and Vietnam), also had presence of lead.
• World Freed from toxic leaded Petrol: UNEP (Aug 2021)
  • Details
    • A global campaign led by the UNEP and its Partnership for Clean Fuels and Vehicles (PCFV) have successfully led to freeing world from the toxic leaded petrol.
  • India and leaded Petrol
    • India was among the early countries to take steps against lead. The process of phase down started in 1994 and got completed in 2000.

B) MERCURY POLLUTION

• Introduction
  • Mercury occurs naturally in the earth’s crust, but human activities, such as mining and fossil fuel combustion, have led to widespread global mercury pollution.
  • Mercury emitted into the air eventually settles into water or onto land where it can be washed into water. Once deposited, certain microorganisms can change it into methylmercury, a highly toxic form that builds up in fish, shellfish and animals that eat fish.
• Prescribed standards by Indian government and WHO
  • Drinking water: 0.001 mg/l
  • Industrial waste: 0.01 mg/l
• Sources of Mercury Pollution
  • An element in the earth’s crust.
  • Other Natural sources include volcanic eruptions and emissions from the ocean.
  • Anthropogenic Sources include:
    • Coal burning power plants are the largest human caused source of
    • Use of Mercury to separate gold from ore bearing rock (another major source of mercury pollution)
  • Other sources of mercury pollution
    • Burning hazardous waste
    • Producing chlorine
    • Breaking mercury products and spilling mercury
    • Improper treatment and disposal of or wastes containing mercury (Kodaikanal Mercury Poisoning by Hindustan lever)
• ­Exposure
  • Most human exposure to mercury is from eating fish and shellfish contaminated with methylmercury
  • Breathing mercury vapor: When products that contain elemental mercury break and release mercury to the air, particularly in warm poorly ventilated indoor spaces.
• Harmful effects: Mercury is poisonous in all forms – inorganic, organic or It is a neurotoxin; it is particularly harmful in the early stages of development, it can impair motor skills and can adversely affect immune system
• ­Airborne Mercury
  • Until recently species that do not eat fish were thought to be safe from the harmful effects of Mercury. However recently researchers have documented mercury in Bicknell’s thrushes, terrestrial birds that inhabit mountain top in northeast Illinois, where habitat lie downwind of the coal burning epicenter of the Ohio.
• Mercury Pollution in India
  • Mercury contamination in India is reaching alarming levels largely due to the discharge of mercury-bearing industrial effluents ranging from 0.058 to 0.268 mg/liter.
  • Centre for Science and Environment have compiled data from various sources to identify critically polluted mercury regions in India:
    • High level of mercury in fish stocks have been found, mainly in coastal areas.
      • Mumbai, Kolkata, Karwar and North Koel (in Bihar) are some of the severely affected areas.
        • Koel river showed mercury concentration almost 600-700 times above the limits.
      • Mercury in ground water and Surface water was detected throughout the country.
      • Further, near industrial units such as chlor-alkali, cement, chemical units and thermal powerplants, levels higher than the permissible limits were found.
• Minamata Convention on Mercury
  • It is an international treaty designed to protect human health and the environment from anthropogenic emissions and release of mercury and mercury compounds.
    • Convention was ratified by delegates from 140 countries in January 2013.
  • Why is global response needed?
    • Mercury pollution is global problem that requires global action because it moves with air and water, transcends political boundaries, and can be transported thousands of miles in the atmosphere.
  • Major Highlights
    • Bans new mercury mines; phase out existing mines.
    • Control measures on air emissions from power
    • Regulate informal sectors like small scale gold mining.
    • Phase out or reduce mercury use in products like batteries switches ;
    • Addresses supply and trade, safer storage and disposal and strategies to address contaminated sites.
    • Technical assistance, information exchange, public awareness and research and monitoring
    • Parties to report on measures taken to implement certain
  • India ratified the convention in
    • This allows India to get technological and financial assistance in the fight against mercury
    • The convention has given five year time to India to control and reduce emissions from new power plants and 10 years’ time for already existing power plants.
• Minamata COP-5 (Nov 2023)
  • Held in Geneva
  • Parties decided new dates to phase out mercury-added products including cosmetics,
  • Strengthened ties with indigenous people.
  • Advanced the first effectiveness evaluation of the convention.
  • Reached an agreement on a threshold for mercury waste.

C) ARSENIC POLLUTION

• Introduction
  • Arsenic is an odorless and tasteless metalloid which is widely distributed in the earth’s crust.
    • Periodic Table: Elemental arsenic is a member of Group VA of the periodic table, with nitrogen, phosphorus, antimony and bismuth. It has an atomic number of 33 and an atomic mass of 74.91
  • Arsenic contamination of the ground water is one of the most serious drinking water issue being faced in India.
  • BIS stimulates a permissible limit of 0.01 mg/L of arsenic in water. But, as per the latest CGWB study, 21 states across the country have pockets of arsenic levels higher than this limit.
• ­Key Areas impacted by Arsenic Pollution in India
  • The states in Ganga-Brahmaputra-Meghna river basin are the most affected. They include – UP, Bihar, Jharkhand, WB, and Assam.
  • Other arsenic affected areas include Punjab, Haryana, Manipur, Chhattisgarh and Karnataka.
• Sources of Arsenic Pollutionzxe
  • Arsenic is introduced in soil and groundwater through weathering of rocks and minerals followed by subsequent leaching and runoff.
  • Anthropogenic sources – coal fired power plants, burning vegetation, and Volcanism.
  • Ground water contaminated with Arsenic is also entering food chain.
    • The chemical has found its way into rice, wheat and potato. A unique observation was that in several samples, arsenic content in food items was higher than that in drinking water.
• Impact
  • Long-term intake of arsenic polluted water leads to arsenic poisoning or arsenicosis, with cancer of skin, bladder, kidney or lung or diseases of skin, blood vessels of legs and feet.
• Key Recent steps:
  • Under Jal Jivan Mission (Har Ghar Nal se Jal), since, planning, implementation, and commissioning of piped water supply scheme based on a safe water source may take time, purely as an interim measure, state and Uts have been advised to install community water purification plants (CWPP) especially in Arsenic and Fluoride affected habitations to provide potable water to every household at the rate of 8-10 litres per capita per day to meet their drinking and cooking requirements.

D) RADIOACTIVE POLLUTION IN WATER

• ­Details
  • Radioactive pollution of water is a newly emerging, but grave concern of water pollution and human health.
  • Radioactive elements are naturally found in earth’s crust. Percolation of naturally occurring radioactive materials (NORM) from the soil sediments to the aquifer causes groundwater contamination.
  • Anthropogenic sources include:
    • Nuclear weapon investigation.
    • nuclear calamities.
    • nuclear powerhouse;
    • dumping of radioactive waste are the major sources.
    • Use of radioisotopes in industries and scientific laboratories are the minor sources.
  • This pollution is more prevalent in groundwater as compared to surface water since it is much exposed to radioactive elements found in rocks. Sometimes magma also releases radioactive gases in environment.
  • A number of radionuclides are found in surface and sub-surface waters, among which 3H, 14C, 40K, 210Pb, 210Po, 222Rn, 226Ra, 228Ra, 232Th, and 234,235, 238 U are common.
    • Uranium, thorium, and actinium are three NORM series that contaminate water resources.
    • Radium, a descendent of NORM series, is one of the decidedly radiotoxic elements found in aquatic systems and can be penetrated into groundwater via (i) acquifer rock dissolution (ii) decaying of 238U and 232Th, or (iii) desorption process
• How is radioactivity measured?
  • It is measured in Becquerel (SI unit) or in curies.
    • Energy absorbed per unit mass is measured by Gray, while the unit Sievert measures the quantity of radiation absorbed by human tissues.
• A small amount of radiation is found in all types of water, but the extended amount of radiation is harmful to human health.
• Harmful Impacts of nuclear radiation:
  • Immediate: recoverable consequences distressing skin, lungs, genitals, and causing of hair fall.
  • Long standing: permanent outcomes such as various infections like radiation damage, bone marrow fatality, cataract initiation, cancer stimulation, cholera, etc.
  • Genetic effects: ionizing radiation induces mutations in germ cells
• ­WHO guideline:
  • Guidelines for drinking water quality and a permissible limit of reference dose level of 0.1 micro- sieverts per year.

E) THERMAL POLLUTION: WATER POLLUTION FROM THERMAL POWER PLANTS

• Thermal Pollution is the degradation of water quality by any process that changes ambient water temperature.
• Heat is considered a water pollutant if it is caused by human activities.
• Major causes of thermal pollution include:
  • Coolant from thermal power plants
  • Industry effluents
  • Alteration of vegetation cover – increases the heating of
• ­Negative impact of Thermal Pollution
  • Oxygen deficiency (reduced solubility and high metabolism)
  • Temperature sensitive aquatic organisms die.
  • Decrease in decomposition of organic matter (oxygen deficiency leads to aerobic decomposers not functioning effectively)
  • Primary productivity and diversity of aquatic plant species decline
• Note: Even unnatural lowering of temperature of a water body is harmful.
  • Aquatic biodiversity is very sensitive to temperature change.

2) MARINE POLLUTION

A) LISBON DECLARATION

• ­Why in news?
  • All 198 members of the UN have unanimously adopted the Lisbon Declaration on Ocean Conservation in July 2022 on the last day of the UN Ocean Conference 2022.
• ­Details
  • Participants agreed to work on preventing, reducing and controlling marine pollution. It includes:
    • Nutrient Pollution
    • Untreated Wastewater
    • Solid Waste Discharges
    • Hazardous Substances
    • Emissions from the marine sector, including shipping, shipwrecks
    • Anthropogenic underwater noise
  • The nations committed to follow science based and innovative action on an urgent basis.
  • They also agreed that developing countries (particularly small island developing states) and LDCs need assistance with capacity building.
  • Developing and promoting innovative financing solutions to help create sustainable ocean- based economies as well as expanding nature-based solutions to help conserve and preserve coastal communities.
  • Member nations also committed to empowering women and girls, recognizing their participation is crucial to building a sustainable ocean-based economy and achieving the UN- mandated SDG14.
• The conference has set the stage for the fifth session of the intergovernmental conference on an international legally binding instrument for the conservation and sustainable se of marine biological diversity of areas beyond national jurisdiction.

B) HIGH SEAS TREATY

• ­Why in news?
  • Negotiators from almost every country in the world finalized a new global treaty meant for conservation of sustainable use of biological resources in the high seas (March 2023)
• ­Background:
  • The High seas are open ocean areas that are outside the jurisdiction of any country. It consists of around 64% of the ocean surface and around 43% of earth. These are home to millions of marine species and trillions of micro-organisms.
  • Existing Legal Framework for High Seas:
    • UNCLOS
    • Antarctic Treaty System
  • Limitations:
    • UNCLOS is not primarily focused on sustainability and environment Though, it asks countries to protect the ocean ecology and conserve its resources, it doesn’t provide the specific mechanisms or processes to do so.
• Technical Name of the Treaty: the ‘Agreement under the UNCLOS on Conservation and Sustainable use of marine biodiversity in areas beyond national jurisdiction (BBNJ))
• Key Highlights of the Treaty:
  • The nations of the world have agreed to a Framework for the Conservation and Sustainable Use of Resources in the open oceans.
  • The High Seas Treaty will work as an implementation agreement under UNCLOS, much like Paris Agreement under UNCLOS.
  • Key Provisions:
    • The treaty has Four Main Objectives:
      • Demarcation of Marine Protected Areas (MPAs), rather like there are protected forest and wildlife areas.
        • Under this, a state or group of states can submit a proposal for MPA along with relevant It also provides guidelines for implementation, monitoring, and review of MPAs established.
        • Note: As of now, only 44% of high seas are protected according to IUCN.
      • Sustainable use of marine genetic resources and equitable sharing of benefits arising from them.
      • Initiation of the process of Environmental Impact Assessments for all major activities in the oceans
        • The agreement includes an obligation to conduct EIAs for activities with potential impacts on the high seas that will apply to new activities such as geo-engineering.
        • It also includes a new impact threshold to trigger a screening process, which means more activities will now be subject to at least some assessment.
      • Capacity building and Technology transfer.

Marine Protected Areas	MPAs are where ocean systems, including biodiversity, are under stress, either due to human activities or climate change. These can be called the national parks or wildlife reserves of the oceans. Activities in these areas will be highly regulated, and conservation efforts similar to what happens in forest or wildlife zones, will be undertaken
Marine Genetic Resources	Oceans host very diverse life forms, many of which can be useful for human beings in areas like drug development. Genetic information from these organisms is already being extracted, and their benefits are being investigated. The treaty seeks to ensure that any benefits arising out of such efforts, including monetary gains, are free from strong intellectual property rights controls, and are equitably shared amongst all. The knowledge generated from such expeditions are also supposed to remain openly accessible to all
Environmental Impact Assessment	The high seas are international waters that are open for use by all countries. Under the provisions of the new treaty, commercial or other activities that can have significant impact on the marine ecosystem, or can cause large-scale pollution in the oceans, would require an environmental impact assessment to be done, and the results of this exercise have to be shared with the international community
Capacity Building and Technology Transfer	The treaty lays a lot of emphasis on this, mainly because a large number of countries, especially small island states and landlocked nations, do not have the resources or the expertise to meaningfully participate in the conservation efforts, or to take benefits from the useful exploitation of marine resources. At the same time, the obligations put on them by the Treaty, to carry out environmental impact assessments for example, can be an additional burden

• • • COP, which acts as the decision making body of the treaty, will take the work forward and will also act as a platform to work with existing authorities that regulate fishing, shipping and mining.
  • Difficult road ahead:
    • The treaty is a result of 20 years of protracted negotiation. The details of all the major contentious provisions, including EIA, sharing of benefits from genetic resources, and mobilization of funds for conservation activities, are still to be worked Many issues remain unaddressed, including mechanisms for policing the protected areas, the fare of the projects that are addressed to be heavily polluting, and resolution of disputes.
    • Process of ratification is also not going to be easy. (UNCLOS took 12 years to become international law and Kyoto Protocol took 8 years – because necessary number of ratifications were not achieved)
      • Treaty must be ratified by a minimum 60 countries for it to come into force

C) MARINE LITTER / MARINE PLASTIC POLLUTION

• ­Introduction:
  • What is marine litter?
    • It’s any man-made, long standing solid material that humans have incorrectly disposed of and that has ended up on the beach, in estuaries, rivers, seas and ocean.
    • Plastic is the most common type of litter found at sea. Around 8 million tonnes of plastics end up in the world’s ocean every year. It is estimated that more than 1 lakh of turtles and marine mammals die every year due to these plastic marine litter. It is estimated that around 18,000 plastic pieces are floating on every square kms of the world’s ocean.
  • Reasons for Increasing Marine Litter:
    • Very slow rate of degradation of litter items, mainly plastic
    • Continuously growing quantity of the litter and debris disposed in oceans due to increased population, industrialization, single use plastics etc.
    • Harmful impacts
      • Affects public health (plastics have now been found in human blood).
      • Threatens marine ecosystem
        • Animals get trapped in this litter. They also sometimes confuse marine litter with food.
        • Ghost Fishing: Nets, Fish Aggregation Devices (FAD) and other gears continue to fish for decades after getting discarded.
      • Impacts fishery and tourism sector
• Key steps taken by India:
  • Marine Plastics Survey Program of NCCR (National Centre for Coastal Research)
    • This program studied the distribution of microplastics in coastal locations in the Bay of Bengal and Arabian Sea in particular along the International Shipping Routes.
    • It found that 50% composition of marine litter was by single use plastics from 2018 – 2021 at various beaches of India.
  • 2021 Amendment to Plastic Waste Management Rules, 2016
    • Ban on several single use plastic from July 2022;
    • Increase in thickness of plastic
  • EPR guidelines related to Plastic packaging materials.
  • Swatch Sagar Surakshit Sagar:
    • Commemorating the 75th year of India’s independence, a coastal cleanup drive was carried out at 75 beaches across the country across 75 days over 7500 km long coastline. This unique first ever national campaign culminated on “International Coastal Clean-Up Day” on 17th Sep 2022.
    • This drive was aimed at removing 1,500 tonnes of garbage from the sea coast which will be a huge relief to marine life and the people staying in coastal regions.
  • At UN Ocean Conference in Lisbon, India has assured the world community that under PM Modi, it is committed to protecting at least 30% of our lands, waters and oceans, and thus adhere to its commitment of 30X30 by 2030 in a mission mode.
    • Note: India is part of the High Ambition Coalition for Nature and People, which was initiated at the “One Planet Summit” in Paris in January 2021, to promote an international agreement to protect at least 30 per cent of the world’s land and ocean by 2030
  • International Cooperation: Under the Commonwealth Litter Program (CLiP), the UK’s Centre for Environmental Fisheries and Aquaculture Sciences (CEFAS) and India’s National Centre for Coastal Research (NCCR) launched a pilot project to understand deteriorating sea water quality due to marine litter.
• Key International Initiatives:
  • London Dumping Regime (of International Maritime Organization): it regulates deliberate dumping of plastic waste at sea from vessels and platforms.
  • International Convention for the Prevention of Pollution from Ships (MARPOL): It regulates both deliberate and accidental discharge of plastics from vessels.
  • But, the problem with both these rules is lack of enforcement. It is hard to monitor and enforce the prohibition on plastic pollution from vessels on the high seas. Flag states often lack incentives to do so.

D) OCEAN DEOXYGENATION

• ­Ocean Deoxygenation
  • It is the phenomenon of oxygen loss in ocean caused by excessive growth of algae due to nutrient pollution. The nutrient pollution may be caused by fertilizers, sewage, animal or aquaculture waste.

• The IUCN Report ‘Ocean deoxygenation: Everyone’s problem’ is the largest peer reviewed study to date of the causes, impacts, and potential solutions to ocean deoxygenation.
• ­Key Findings
  • Ocean regions with low oxygen concentration have expanded to all depths of the Ocean
  • The volume of area depleted with oxygen, known as “anoxic waters / dead zones” have quadrupled.
  • What if the present situation continues?
    • Under a business-as-usual scenario, the ocean is predicted to lose 3-4% of its global oxygen by 2100.
      • Local changes will be more severe.
    • Further, most of the oxygen loss will take place in the upper 1,000 meters, which is the richest part of the Ocean for biodiversity.
• ­ Reasons for Ocean Deoxygenation
  • Climate Change and Nutrient Pollution are the main drivers of the ocean oxygen loss.
  • Ocean oxygen loss is also closely related to Ocean Warming and Acidification caused by anthropogenic carbon di oxide emissions and biogeochemical consequences related to anthropogenic fertilization of the ocean.
• Adverse impact of low oxygen levels
  • Balance of Marine Life: The IUCN report has started impacting the balance of marine life, favoring species tolerant of low-oxygen conditions, like jellyfish, some squid and microbes, at the expense of species sensitive to low-oxygen, including most fish and many marine species.
  • Negatively hamper cycles of nitrogen and phosphorus

E) SARGASSO SEA WEED

• About Sargasso Seaweed
  • Between 2000-2010 there was little sea weed in the central Atlantic: most was found in the Gulf of Mexico and Saragossa Sea.
  • Explosion in Sargassum seaweed first materialized in 2011. It developed in subsequent years into a vast band – in 2018 this stretched for 5,500 miles.
    • The bloom peaks in the middle of the year and develop larger from small populations of the seaweed in the central Atlantic, with some contributions from west Africa.
    • A number of natural and man-made factors align together to make this
  • Problems caused by this explosion.
    • Thick mats can block sunlight
    • Sometimes, when they die and sink, they may be deadly for fish and Corals.
    • They are also proving disastrous for humans. Increasingly huge quantities are washing up in tourist destination, creating stinking masses that threaten the tourism industry and pose a threat to health.
  • Reasons:
    • Alignment of circumstances like conducive sea-surface temperature and salinity combining with an increase in nutrients – in part from the upward movement of cool, nutrient rich water in the eastern Atlantic and an increase in discharge from the Amazon in the preceding years.
• About Sargasso Sea
  • Located entirely within the Atlantic Ocean, it is the only sea without a land boundary. While all other seas in the world are defined at least in part by land boundaries, the Sargasso Sea is defined only by ocean currents. It lies within the Northern Atlantic Subtropical Gyre. The Gulf Stream establishes the Sargasso Sea’s western boundary, while the Sea is further defined to the north by the North Atlantic Current, to the east by the Canary Current, and to the south by the North Atlantic Equatorial Current. Since this area is defined by boundary currents, its borders are dynamic, correlating roughly with the Azores High Pressure Center for any particular season.
  • It has been named after genus of a free floating seaweed called Sargassum.
    • While there are many different types of algae found floating in the ocean all around world, the Sargasso Sea is unique in that it harbors species of sargassum that are ‘holopelagi‘ – this means that the algae not only freely floats around the ocean, but it reproduces vegetatively on the high seas. Other seaweeds reproduce and begin life on the floor of the ocean.
    • Sargassum provides a home to an amazing variety of marine species.
      • Turtles use sargassum mats as nurseries where hatchlings have food and shelter. It also provides essential habitat for shrimp, crab, fish and other marine species.

F) DEAD ZONES

• Introduction
  • Excess nutrient pollution in oceans/lakes create a situation of hypoxia i.e. reduction in availability of oxygen in the water. This situation is often referred as Dead zone as most marine life either dies, or if they are mobile, leave the area. Because of creation of dead zones, habitats which are normally teeming with life become essentially biological deserts.
• Can Dead zone occur naturally?
  • Yes, dead zones may occur naturally. But, environmentalists are concerned about those which are created or enhanced by human activities.
• ­Key factors responsible for creation of dead zones?
  • There are many physical, chemical and biological factors that combine together to create dead zones, but nutrient  pollution  is  the  primary cause of those zones created by human activities.
  • Nutrients -> Algae -> Decomposition -> Oxygen Depletion.
  • Climate Change -> Rising temperatures -> reduce the dissolved oxygen, increase metabolism rate and oxygen demand.

G) THE GREAT PACIFIC GARBAGE PATCH (GPGP)

• The Great Pacific Garbage patch is located about halfway between Hawaii and California. It is the largest accumulation zone of ocean plastic on earth.
• It consists of higher concentration of waste item, but much of the debris is actually small pieces of floating plastic that are not immediately evident to naked eyes.
• While great pacific patch is a term regularly used in the media, it doesn’t paint the correct picture of the marine pollution problem in the North Pacific Ocean. Marine debris concentrates in various regions of the North-Pacific, not just in one area. The exact size, content, and location of the “garbage patches“ are difficult to accurately predict.

• Why is it difficult to clean up the patches?
  1. Very large and shifting area
  2. Uneven distribution of debris
  3. Small pieces of plastic forms the largest chunk
  4. Marine life doesn’t allow simple skimming of these debris