MEVE 019: Unit 10 - Marine Pollution

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 UNIT 10: MARINE POLLUTION

10.1 Introduction

Marine pollution is one of the most pressing global environmental challenges today. It refers to the introduction of harmful substances and waste into oceans, seas, and coastal areas. These pollutants—ranging from plastics and chemicals to oil and heavy metals—threaten marine ecosystems, biodiversity, fisheries, and even human health. With growing industrialization, urbanization, and maritime activities, oceans have become dumping grounds, disrupting their ecological balance.

10.2 Objectives

By the end of this unit, learners will be able to:

·         Define marine pollution and identify its major sources.

·         Understand the extent, intensity, and mechanisms of marine pollution.

·         Describe the ecological impacts of marine and deep-sea pollution.

·         Explore current management strategies, policies, and control measures.

10.3 Definition of Marine Pollution

Marine pollution is defined as:

The introduction by humans, directly or indirectly, of substances or energy into the marine environment which results in harmful effects such as damage to living resources, hazards to human health, hindrance to marine activities, and impairment of water quality.

It affects coastal waters, deep seas, coral reefs, and marine food chains.

10.4 Sources and Causes of Marine Pollution

·         Land-based Runoff: The largest contributor; includes sewage, agricultural runoff (pesticides, fertilizers), and industrial waste.

·         Oil Spills: Leakages from tankers, offshore drilling, and shipping accidents pollute vast ocean areas.

·         Marine Dumping: Deliberate disposal of garbage, plastics, and chemicals into the sea.

·         Atmospheric Deposition: Airborne pollutants like heavy metals and hydrocarbons eventually settle in oceans.

·         Shipping and Port Activities: Release of ballast water, bilge oil, and noise pollution.

·         Plastic Waste: Millions of tons of plastic enter oceans annually, breaking down into microplastics.

·         Deep-sea Mining and Dredging: Disrupt sediments and release toxic substances.

10.5 Effects of Marine Pollution

·         Threat to Marine Life: Toxins, plastics, and chemicals are ingested by fish, seabirds, and marine mammals.

·         Loss of Biodiversity: Coral reefs, mangroves, and seagrass beds are damaged.

·         Bioaccumulation and Biomagnification: Toxins accumulate in organisms and intensify through the food chain.

·         Human Health Risks: Contaminated seafood causes diseases; polluted beaches and waters are unsafe for recreation.

·         Economic Losses: Affects tourism, fisheries, and coastal livelihoods.

10.6 Extent of Marine Pollution

·         According to UNEP, over 80% of marine pollution originates from land-based sources.

·         Over 11 million tonnes of plastic waste enter oceans each year.

·         Oil spills like Deepwater Horizon (2010) highlight the severity of industrial marine pollution.

·         Dead zones (oxygen-depleted areas) are expanding globally due to nutrient runoff.

10.7 Intensity of Marine Pollution

The intensity depends on:

·         Proximity to urban centers and industrial zones

·         Level of maritime traffic

·         Coastal vs. deep-sea ecosystems

·         Ocean currents and seasonal cycles

Shallow coastal zones are more heavily polluted due to accumulation and limited circulation.

10.8 Mechanism and Process of Marine Pollution

1.      Discharge and Deposition: Pollutants enter the water through direct discharge or via rivers and runoff.

2.      Dispersal and Dilution: Pollutants spread with currents, tides, and wind but may not degrade.

3.      Sedimentation: Heavy metals and toxic materials settle on the ocean floor.

4.      Ingestion and Absorption: Marine organisms absorb or ingest toxins, leading to food chain contamination.

10.9 Ecological Impacts of Marine Pollution

·         Coral Bleaching: High temperatures and chemical stress damage coral reefs.

·         Mass Fish Deaths: Oil, toxins, and oxygen depletion cause large-scale marine deaths.

·         Altered Reproductive Systems: Hormonal disruptions in fish and other aquatic life.

·         Microplastic Invasion: Found in marine organisms, seawater, and even deep-sea trenches.

10.10 Ecological Consequences of Deep-sea Mining

·         Sediment Plumes: Disturb the seabed, smother organisms, and affect filter feeders.

·         Toxic Releases: Heavy metals like mercury and lead are released from disturbed rocks.

·         Noise Pollution: Affects whales, dolphins, and other acoustically sensitive species.

·         Loss of Unknown Biodiversity: Many deep-sea species remain undocumented and risk extinction.

10.11 Management and Policy

10.11.1 Oil Pollution Control Measures

·         Booms and Skimmers: Physical containment and removal of oil.

·         Bioremediation: Using microbes to break down oil spills.

·         Chemical Dispersants: Break oil into smaller droplets (with caution due to toxicity).

·         International Conventions: MARPOL (International Convention for the Prevention of Pollution from Ships).

10.11.2 Measures to Control Heavy Metal Pollution

·         Strict Industrial Regulation: Pre-treatment before discharge into rivers.

·         Monitoring and Compliance: Enforcing emission limits.

·         Wetland Use: Natural filters for capturing heavy metals.

10.11.3 Measures to Reduce Ship Pollution

·         Cleaner Fuels and Technologies: Reduce SOx, NOx, and CO₂ emissions.

·         Ballast Water Management: Prevent spread of invasive species.

·         Proper Waste Disposal: On-board treatment and disposal protocols.

·         Port Reception Facilities: For proper handling of ship waste.

10.11.4 Suggestions and Prospects

·         Integrated Coastal Zone Management (ICZM)

·         Public Awareness and Participation

·         Ban on Single-Use Plastics

·         Support for Research and Innovation

·         Strengthening of International Collaboration

10.12 Let Us Sum Up

Marine pollution, largely caused by human activities, is threatening the very foundation of marine ecosystems and biodiversity. Pollutants from land, oil spills, plastics, and heavy metals affect aquatic life, food safety, and economies. Deep-sea mining further compounds these risks. Management strategies—ranging from technological innovations to international policies—must be urgently implemented to prevent irreversible damage. Protecting the oceans is not only vital for environmental health but also for human survival and sustainable development.

 

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