Rucete ✏ AP Environmental Science In a Nutshell
8. Aquatic and Terrestrial Pollution
This unit explores how pollutants from human activities impact terrestrial and aquatic ecosystems. Topics include pollution sources, bioaccumulation, eutrophication, endocrine disruptors, waste management strategies, sewage treatment, and the effects of pathogens and infectious diseases on human health.
8.1 Sources of Pollution
Air Pollution
• Caused by fossil fuel combustion, industrial emissions, and mining.
• Leads to acid rain, smog, global warming, ozone depletion, and health issues.
Noise Pollution
• Sources: industrial machines, social events, transportation.
• Effects: hearing loss, hypertension, sleep disorders, stress.
Soil Pollution
• Sources: acid rain, industrial waste, farming chemicals, mining.
• Effects: reduced fertility, harmful dust, bioaccumulation in food chain.
Water Pollution
• Causes: oil spills, sewage, runoff, eutrophication.
• Effects: ecosystem disruption, toxin bioaccumulation, disease spread.
• Point source: known origin (e.g., pipe).
• Non-point source: diffuse sources (e.g., runoff).
8.2 Human Impacts on Ecosystems
Chemical Pollution
• Includes heavy metals, PAHs, pharmaceuticals, detergents, pesticides.
• Contaminate fish, water, soil, and humans through food chains.
Oil & Gas Extraction
• Leaking tanks and drilling operations pollute coastal and groundwater.
Hormones & Drugs
• Hormones in agriculture and pharmaceuticals affect fish and amphibians.
8.3 Endocrine Disruptors
Definition
• Chemicals that interfere with hormone systems in humans and animals.
Examples
• BPA, dioxins, phthalates, PCBs.
• Found in plastics, cosmetics, pesticides, electronics.
Effects
• Birth defects, cancer, infertility, neurological damage.
• Difficult to remove from environment once released.
8.4 Human Impacts on Wetlands and Mangroves
Wetlands
• Transitional zones between land and water (e.g., swamps, bogs, marshes).
• Provide flood control, filtration, carbon storage, habitat, and erosion prevention.
Mangroves
• Coastal tropical wetlands with salt-tolerant trees.
• Buffer shorelines from storms, support fisheries, and reduce erosion.
Threats
• Agriculture, aquaculture, urban development, road construction, and pollution degrade these ecosystems.
• Wetland loss reduces water quality, biodiversity, and natural flood control.
8.5 Eutrophication
Process
• Excess nutrients (mainly nitrogen and phosphorus) enter aquatic systems, often from fertilizer or sewage.
• Leads to algal blooms → algae die → decomposition consumes oxygen → hypoxia → fish kills and biodiversity loss.
Dead Zones
• Hypoxic areas in oceans or lakes where most marine life cannot survive.
• Example: Gulf of Mexico dead zone at Mississippi River delta.
Solutions
• Reduce fertilizer use and improve agricultural practices.
• Treat sewage and runoff before discharge.
• Restore wetlands to absorb nutrients naturally.
8.6 Thermal Pollution
Causes
• Discharge of heated water from power plants or factories into natural water bodies.
Effects
• Warmer water holds less dissolved oxygen → reduces aquatic life survivability.
• Alters reproduction, metabolism, and migration of fish and invertebrates.
Solutions
• Cooling towers and ponds, recycled cooling systems, and strict discharge regulations.
8.7 Persistent Organic Pollutants (POPs)
Definition
• Toxic chemicals that persist in the environment, bioaccumulate through the food web, and pose health risks to humans and wildlife.
Examples
• DDT, PCBs, dioxins, aldrin, endrin, toxaphene.
• Commonly found in pesticides, industrial chemicals, and combustion byproducts.
Effects
• Endocrine disruption, reproductive failure, immune suppression, cancer, developmental damage.
• Transported globally via air and water currents; can accumulate in polar regions.
Regulation
• Stockholm Convention (2001): international treaty to eliminate or restrict POPs.
8.8 Solid Waste Disposal
Types of Waste
• Municipal solid waste (MSW): household and commercial trash.
• Industrial waste: from manufacturing and processing.
• Hazardous waste: toxic, flammable, corrosive, or reactive substances.
Disposal Methods
• Sanitary landfills: compacted, lined, and covered waste; produce methane and leachate.
• Incineration: reduces volume; may generate electricity but emits pollutants.
• Recycling: conserves materials, reduces landfill need and energy use.
• Composting: decomposes organic waste into soil-like product.
Hazards
• Leachate can contaminate groundwater.
• Air pollution from burning and decomposing waste.
• Space and land use issues in urban areas.
8.9 Waste Reduction Methods
3 Rs Approach
• Reduce: minimize waste generation (e.g., reusable bags, buying less).
• Reuse: extend product life by using items multiple times.
• Recycle: process materials into new products (requires energy and separation).
Other Strategies
• Composting, e-waste recovery, sustainable packaging, producer responsibility programs.
8.10 Sewage Treatment
Primary Treatment
• Physical process: screens and settling tanks remove large solids (grit, debris, sludge).
Secondary Treatment
• Biological process: bacteria break down organic matter (BOD – biological oxygen demand).
• Aeration tanks and clarifiers reduce waste concentration.
Tertiary Treatment
• Advanced treatment: removes nutrients (nitrates, phosphates), heavy metals, or pathogens.
• May involve filtration, chemicals, UV, or chlorination.
Disinfection
• Chlorine, ozone, or UV used before discharge to kill remaining pathogens.
Sludge Disposal
• Treated and disposed via incineration, land application, or landfills.
8.11 Lethal Dose (LD50)
Definition
• LD₅₀ is the dose at which 50% of a test population dies from exposure to a substance.
Use
• Used to measure toxicity of chemicals in lab animals.
• Lower LD₅₀ = more toxic.
8.12 Dose Response Curves
Dose-Response Relationship
• Plots the effect of a toxin against its dose.
• Threshold: the minimum dose at which effects appear.
• Helps set exposure limits and determine relative safety.
8.13 Pathogens and Infectious Diseases
Sources
• Waterborne pathogens from untreated sewage and animal waste.
• Diseases include cholera, dysentery, hepatitis A, Giardia, and typhoid.
Global Impacts
• More prevalent in developing countries with poor sanitation.
• Contribute to millions of deaths annually, especially in children.
Solutions
• Improve wastewater treatment, sanitation, and water filtration.
• Promote hygiene, vaccination, and safe water access.
In a Nutshell
Pollution affects both aquatic and terrestrial ecosystems through diverse pathways—nutrient loading, toxic chemicals, thermal changes, solid waste, and biological contamination. Eutrophication, endocrine disruption, and disease spread highlight the complexity of human impacts. Solutions include better waste treatment, reduced emissions, sustainable land use, and education. Managing pollution holistically is key to protecting environmental and public health.