Lecture - 24

Coastal pollution

Contamination is, used to describe the fact that a certain chemical compound is present in a certain habitat and/or the organisms living there, at a concentration higher than normal or the background value, and this due to non-natural causes.

Pollution can then be defined as any form of contamination in an ecosystem with a harmful impact upon the organisms in this ecosystem, by changing the growth rate and the reproduction of plant or animal species, or by interfering with human amenities, comfort, health, or property values. In a broader sense, the terms contamination and pollution also include any physical modification that alters the energy or radiation flow in an environment (such as a heat source or sink, or a radioactive element), or even the presence of an invasive species.

Hence, marine pollution as defined by the Group of Experts on the Scientific Aspects of Marine Pollution (GESAMP), as part of the basic framework of the UN Convention on the Law of the Sea (UNCLOS) 1982 (Article 1.4), is:

“The introduction by man, directly or indirectly, of substances or energy into the marine environment (including estuaries) resulting in such deleterious effects as harm to living resources, hazards to human health, hindrance to marine activities including fishing, impairment of quality for use of sea water, and reduction of amenities.”

Reference: Geert Potters. (2015). Marine pollution (1st ed.)

Classification of Pollution Forms

Pollutants can be categorized based on their physicochemical properties, physical state, environmental persistence, and source.

1. Physicochemical Constitution: Pollutants are either inorganic (e.g., NO, NO₂, SO₂, metal ions) or organic (e.g., wastewater, agricultural runoff, petroleum derivatives). Non-chemical forms, such as sound and light, also contribute to pollution.

2. Physical State: Pollutants exist in solid (e.g., plastic debris, sludge), gaseous (e.g., volatile organic compounds), or particulate forms (e.g., airborne ashes, heavy metals on dust). Waterborne pollutants include solutes like fertilizers, antibiotics, and hormones.

3. Persistence:

o Biodegradable: Pollutants like sewage, manure, and cooking waste are broken down by microorganisms.

o Dissipative: Heat from cooling water, acids/bases neutralized by ocean buffering, and cyanides diluted in seawater fall into this category.

o Persistent: Metals, radioactive materials, chlorofluorocarbons, dioxins, and pesticides resist degradation and often bioaccumulate in higher trophic levels.

4. Source:

o Point Source: Originates from a specific location (e.g., sewage pipes, oil spills, windmill noise).

o Nonpoint Source: Diffuse and hard to trace (e.g., agricultural runoff, urban stormwater, mining dust). Nonpoint sources are the leading cause of water pollution in the U.S., particularly agricultural runoff.

Table 1-1. Types, sources, and effects of marine pollution. Compiled by World Watch Institute.

Sources of Marine Pollution

Marine pollution originates from a variety of sources, both natural and human-made (anthropogenic). These sources can be broadly categorized into land-based, marine-based, and atmospheric sources. Below is a detailed breakdown of the major sources of marine pollution:

1. Land-Based Sources (80% of Marine Pollution)

· Agricultural Runoff:

Fertilizers, pesticides, and herbicides wash into rivers and eventually reach the ocean, causing eutrophication (excessive nutrient enrichment leading to algal blooms and dead zones).

· Urban Runoff:

Stormwater carries pollutants like oil, heavy metals, and chemicals from roads, industrial areas, and urban landscapes into the ocean.

· Industrial Discharges:

Factories release toxic chemicals, heavy metals (e.g., mercury, lead), and untreated wastewater into rivers and coastal waters.

· Sewage and Wastewater:

Untreated or poorly treated sewage introduces pathogens, nutrients, and pharmaceuticals into marine ecosystems.

· Plastic Waste:

Improper disposal of plastic products leads to large amounts of plastic debris entering the ocean via rivers and coastal areas.

· Mining Activities:

Runoff from mining operations carries sediments and toxic metals (e.g., arsenic, cadmium) into water bodies.

· Deforestation and Soil Erosion:

Soil erosion increases sedimentation in rivers, which can smother marine habitats like coral reefs.

· Tourism & Coastal Development

Waste from recreational activities

2. Marine-Based Sources

· Shipping and Maritime Activities:

Oil Spills: Accidental spills from tankers or offshore drilling platforms release large quantities of oil into the ocean.
Ballast Water: Ships discharge ballast water containing invasive species, which can disrupt local ecosystems.
Antifouling Paints: Chemicals like tributyltin (TBT) from ship hulls leach into the water, harming marine life.

· Offshore Oil and Gas Exploration:

Drilling activities release oil, chemicals, and drilling muds into the ocean.

· Fishing Activities:

Ghost Fishing: Abandoned or lost fishing gear continues to trap and kill marine life.
Bycatch: Non-target species are caught and often discarded, leading to waste and ecosystem imbalance.

· Aquaculture:

Fish farms release excess feed, antibiotics, and waste into surrounding waters, contributing to nutrient pollution.

3. Atmospheric Sources

· Air Pollution:

Pollutants like sulfur dioxide (SO₂), nitrogen oxides (NOₓ), and heavy metals are carried by wind and deposited into the ocean through rain or dry deposition.

· Greenhouse Gases:

Increased levels of carbon dioxide (CO₂) lead to ocean acidification, affecting shell-forming organisms like corals and mollusks.

· Dust and Particulate Matter:

Dust storms and industrial emissions transport particles that settle on the ocean surface, affecting marine ecosystems.

4. Natural Sources

· Volcanic Eruptions:

Release ash, gases, and heavy metals into the ocean.

· Natural Oil Seeps:

Oil naturally leaks from the ocean floor, though this is a minor contributor compared to human activities.

· Erosion and Sedimentation:

Natural erosion of coastal areas can increase sediment load in the ocean, affecting marine habitats.

5. Newer and Emerging Sources

· Microplastics:

Tiny plastic particles from cosmetics, synthetic clothing, and degraded plastic waste enter the ocean via rivers and wastewater.

· Noise Pollution:

Underwater noise from ships, sonar, and drilling disrupts marine life, particularly cetaceans (whales and dolphins).

· Light Pollution:

Artificial lighting from coastal cities and offshore platforms affects marine species that rely on natural light cycles.

· Pharmaceuticals and Personal Care Products (PPCPs):

Residues from medications, cosmetics, and cleaning products enter the ocean through sewage and wastewater.

6. Global and Transboundary Sources

· Long-Range Transport:

Pollutants like persistent organic pollutants (POPs) and heavy metals can travel long distances through air and water, affecting remote marine areas.

· Ocean Currents:

Pollutants are carried across vast distances by ocean currents, spreading contamination globally.

Marine debris

Marine debris is composed largely of plastics and may include cigar tips, baby diapers, six-pack rings, beverage bottles and cans, tires, disposable syringes, plastic bags, bottle caps and fishing line and gear. Marine debris can be classified into seven groups.

1) Plastic

2) Metal

3) Leather

4) Glass

5) Foam

6) Clothes

7) Long-life packag

Size classification of debris

Marine debris can be broadly categorized based on size into four main types:

1. Mega-debris: Larger than 100 mm (e.g., large plastic items, fishing nets).

2. Macro-debris: Between 20 mm and 100 mm (e.g., plastic bottles, bags).

3. Meso-debris: Between 5 mm and 20 mm (e.g., small plastic fragments).

4. Micro-debris: Smaller than 5 mm (e.g., microplastics, resin pellets).

Microplastics

Microplastics are tiny plastic particles that are less than 5 mm in size. They are further divided into:

Primary Microplastics: Small particles like resin pellets (used in plastic manufacturing) that enter the ocean directly through runoff or accidental spills.
Secondary Microplastics: Fragments broken down from larger plastic items due to weathering and degradation in the marine environment.

Sources of Microplastics

1. Direct Introduction:

o Runoff from land carries microplastics into rivers and oceans.

o Resin pellets lost during transport or manufacturing processes.

2. Weathering of Larger Debris:

o Larger plastic items (meso- and macro-debris) break down into smaller pieces due to sunlight, waves, and physical abrasion.

Environmental Impact

Floating Microplastics: Low-density plastics (e.g., polyethylene, polypropylene) float on the surface and are ingested by filter-feeding marine organisms.
Sinking Microplastics: High-density plastics (e.g., PVC) sink and accumulate in sediments, where they are ingested by bottom-dwelling organisms.
Ecological Consequences: Microplastics can harm marine life by blocking digestive systems, leaching toxic chemicals, and entering the food chain.
Health hazards like decreased immunity, fertility disorders can be witnessed in marine organisms

Effects of Marine Debris on Ecosystems and Biodiversity

Marine debris, particularly plastic pollution, has severe impacts on marine ecosystems and biodiversity. Below is a simplified summary of the key effects:

1. Entanglement

Macroplastic debris (e.g., fishing nets, ropes, and plastic bags) can entangle marine animals like seals, turtles, seabirds, and whales.
Entanglement restricts movement, leading to:

Injuries (e.g., cuts, infections).
Starvation (inability to hunt or feed).
Drowning (inability to surface for air).

Example: Over 44% of seabirds and 43% of marine mammals are affected by entanglement.

2. Ingestion

Marine animals often mistake plastic debris for food, leading to ingestion.
Microplastics (tiny plastic particles) and macroplastics are ingested by a wide range of species, including fish, turtles, seabirds, and marine mammals.
Effects of ingestion:

Blockage of digestive tracts, causing starvation.
Internal injuries (e.g., gut perforation).
False sense of satiation, reducing food intake.

Example: Over 267 species worldwide, including 86% of sea turtles, are known to ingest plastic.

3. Bioaccumulation and Toxicity

Plastics contain toxic chemicals like organic pollutants and heavy metals (e.g., lead, antimony, and tin compounds).
These chemicals can leach out of plastics and enter the food chain, affecting marine life and humans.
Effects:

Bioaccumulation: Toxins build up in the tissues of marine organisms.
Biomagnification: Toxins become more concentrated as they move up the food chain.

Example: Antimony (a toxic metal) has been found in PET bottles, and lead is present in plastic bags.

4. Habitat Destruction

Plastic debris can smother coral reefs and seagrass beds, disrupting habitats and reducing biodiversity.
Floating plastics can transport invasive species to new areas, altering ecosystems.
Example: Floating plastics in the Southern Ocean have been colonized by a wide range of species, affecting local biodiversity.

5. Impact on Marine Species

Seabirds: Over 44% are affected by plastic ingestion or entanglement.
Marine Mammals: Over 43% are impacted, with species like seals and whales suffering from entanglement.
Sea Turtles: 86% of all turtle species are affected, often mistaking plastic bags for jellyfish.
Fish and Invertebrates: Many species ingest microplastics, which can lead to reduced growth and reproductive issues.

6. Global Threat

Plastic pollution is now recognized as a major stressor for marine ecosystems worldwide.
Its high abundance, durability, and ability to travel long distances make it a persistent problem, even in remote areas.

7. Solutions to Plastic Pollution

Reduce: Minimize the use of single-use plastics.
Reuse: Encourage reusable products.
Recycle: Improve recycling systems to manage plastic waste.
Energy Recovery: Convert plastic waste into energy.
Molecular Redesign: Develop biodegradable or less harmful plastics.

Coastal Pollution: Types, Sources, Marine Debris, and Environmental Impacts