Marine Pollution and Dead Zones

Marine Pollution

• Dead Zones: Areas where most life cannot survive. Figure 1.4a shows changes in the area of dead zones in the Gulf of Mexico from 1985 to 2013.
• Dead Zone Growth: The area of dead zones in 2013 was almost double the area of the dead zones in 2012. This area also exceeded the 5-year average.
• Phosphorus and Nitrogen Sources (Figure 1.4b): In 2012, corn and soybean farms (52%) were the largest contributors to phosphorus and nitrogen discharge to the Gulf of Mexico. Other contributors included farms of other crops, livestock, urban sewage, and atmospheric deposition.
• Photograph 1.4d: Shows a coral reef in a dead zone.
• QR Code (Source 1.4c): Links to the formation process of dead zones (video link).

Adverse Socio-Economic Impacts of Dead Zones (Based on Photograph 1.4d)

• Tourism Decline: The presence of dead zones can deter tourists, impacting the local tourism industry.
• Fishing Industry Decline: A decline in the fishing industry as a result of dead zones may drive down incomes for fishermen. This further impacts the livelihood of those involved in fishing.
• Coral Bleaching: Coral bleaching in dead zones.
• Absence of Fish: Dead zones contain few, if any fish. This lack of fish creates economic problems for the fishing industries.

Alleviating Dead Zones

• Sewage Treatment: Treating sewage before discharge into bodies of water reduces the nutrients entering them. Raising sewage charges for farmers is a possible solution to encourage lower sewage produciton.
• Sustainable Farming: Implementing sustainable farming methods, like intercropping and green manure, could limit the use of chemical fertilizers, thereby lowering nutrient runoff.

Oil Spills and Seabirds

• Oil Absorption: Oil can be absorbed by bird feathers. This is opposite of water, where water is repelled.
• Bird Health Impact: Oil may reduce a bird's ability to fly or float, leading to starvation. Birds are also vulnerable to temperature changes because of the covering from the oil on feathers. Exposure to oil may cause health problems. The oil may be ingested by the birds.

Geographical Enquiry Steps

• Planning and Hypothesis: Initial stages of understanding a geographical issue. Identify the question and relevant hypotheses to test.
• Data Collection: Gathering information and data on the topic of interest.
• Data Processing and Presentation: Data is analyzed and organized for presentation.
• Interpretation and Conclusion: Evaluating results to draw meaningful conclusions.
• Evaluation: Critical analysis of the data and method to ensure accuracy.

Formation of Dead Zones (Elaboration)

• Intensive Farming: Excessive fertilizer use may cause nutrients like nitrogen and phosphorus to be washed into the ocean.
• Algal Blooms: Nutrients cause algal blooms in coastal regions.
• Oxygen Depletion: When the algae die, decomposing bacteria consume oxygen, reducing available oxygen in the water.
• Loss of Marine Life: Low oxygen creates dead zones where many marine organisms cannot survive.

Impact of Marine Pollution

• Marine Life Threatening: Solid waste and oil are threats to marine animals by endangering their survival.
• Harmful Chemicals: Sea water may become polluted with heavy metals, oil or chemical wastes, destroying habitats and poisoning marine life.
• Food Chain Contamination: Chemicals and toxins are absorbed by marine life and accumulate in the food chain harming humans.
• Adverse Economic Impacts: Some recreational activities will be suspended if the coastal areas are polluted, resulting in the loss of income for the local economy. Increased medical spending may also be seen due to increased risk of food poisoning. Health risk and economic loss are directly related.

Correct Sequence for Dead Zone Formation

• Excess use of chemical fertilizers.
• Algal Blooms triggered by the excess nutrients
• Bacteria consume oxygen from low levels of oxygen
• Marine life dies due to low oxygen