Unit 8: Aquatic & Terrestrial Pollution

8.1 Sources of Pollutants

Key Concepts:

Point Sources of Pollution

Definition: A single, identifiable source of a pollutant, often localized, making monitoring and regulation straightforward.

Examples:

• Smokestacks from factories and power plants.

• Waste discharge pipes from industrial sites leading directly into bodies of water.

Distinct Characteristics:
Point sources are easily identifiable as they can be traced back to a specific location, often subject to regulations and permits, while nonpoint sources are diffuse and come from multiple, scattered origins, making them harder to control.

Must-Know Pollution Examples:
Point Sources:

• Emissions from coal power plants, contributing to air pollution with harmful pollutants like CO2, NOx, and SO_2 that lead to acid rain and respiratory issues.

• Oil spills, such as the BP Oil Spill, which has devastating effects on marine ecosystems and local economies due to the long-lasting environmental impact.
  Nonpoint Sources:

• Urban runoff containing pollutants like motor oil, fertilizers, and heavy metals that wash into streams and rivers during rainfall.

• Pesticides blown by wind from agricultural fields, contributing to soil and water contamination and affecting non-target species.

Pollution Definitions:
Pollutants are specific harmful substances with identifiable sources and negative effects on human health and the environment, while pollution refers to vague or general contamination by various harmful substances, which is often unacceptable in AP Environmental Science (APES) Free Response Questions (FRQs).

8.2 Human Impacts on Ecosystems

Effects of Pollution on Organisms:

The tolerance levels for pollutants vary greatly among organisms; exceeding these limits leads to detrimental effects:

• Physiological stress, hindering the normal functioning of biological systems.

• Limited growth and reproductive capabilities, disrupting population dynamics.

• Potential mortality, particularly among sensitive species.

Coral Reefs and Pollution:

Factors causing damage include:

• Rising ocean temperatures due to climate change, leading to coral bleaching and increased vulnerability to diseases.

• Sediment runoff from construction and deforestation, smothering coral reefs and blocking sunlight necessary for photosynthesis.

• Destructive fishing practices such as blast fishing and cyanide fishing, which directly damage the reef structure.

Effect of oil spills:

• Coating wildlife leads not only to mortality but also long-term health issues such as reproductive problems.

• Economic impacts on tourism and fishing industries, affecting livelihoods in coastal communities.

Acid Rain Impacts:

• Decreases in pH can lead to the decline of sensitive organism populations, including amphibians and fish.

• Heavy metal toxicity affects aquatic life and results in disrupted osmolarity, harming physiological regulation.

Human Activities and Coral Reefs:

• Greenhouse gas emissions lead to warming and bleaching of corals, drastically affecting biodiversity.

• Urban runoff increases concentrations of sediment, pesticides, and toxins in water bodies, further straining coral health.

• Overfishing disrupts ecological balance, leading to the proliferation of certain species that can outcompete coral for resources.

8.3 Endocrine Disruptors & Industrial Water Pollutants

Key Characteristics:

Endocrine disruptors are substances capable of interfering with hormonal systems in animals and humans, leading to various health issues.

Examples of endocrine disruptors:

• Atrazine, commonly used in agricultural weed control, linked to reproductive problems.

• PCBs, industrial pollutants with a history of use in electrical equipment, associated with cancer and immune system damage.

• DDT, once widely used for pest control, known for causing eggshell thinning in birds.

• Phthalates, prevalent in plastic production, linked to hormonal imbalances and developmental issues.

Sources:

• Human medications from sewage, which can disrupt aquatic ecosystems and lead to unintended effects on wildlife.

• Heavy metals reach groundwater and aquatic environments through industrial practices and improper waste disposal, posing significant health risks.

8.4 Human Impacts on Wetlands and Mangroves

Wetland Characteristics:

Wetlands are areas where soil is covered by water at least part-time, providing critical ecosystem services:

• Water filtration, improving water quality by trapping pollutants.

• Flood protection by absorbing excess rainfall and reducing runoff.

• Habitat for a diverse range of species, serving as breeding grounds and migratory stopovers.

Threats:

• Pollution from agricultural runoff, leading to nutrient loading and degradation of water quality.

• Commercial development, resulting in habitat destruction and fragmentation.

• Overfishing, which depletes fish populations and disrupts food webs.

Conservation Efforts:

• Enhancing nutrient removal using constructed wetlands to filter runoff.

• Establishing riparian buffers around waterways to protect and restore habitats.

8.5 Eutrophication

Definition: Eutrophication is the process of nutrient enrichment, primarily from agricultural runoff leading to excessive growth of algae, known as algal blooms.

Causes:

• Agricultural runoff containing phosphates and nitrates promotes algae growth.

• Wastewater from urban areas contributing additional nutrients directly to water bodies.

Effects:

• Algal blooms result in hypoxia, where oxygen levels fall below the threshold necessary for aquatic life.

• Dead zones are formed due to oxygen depletion, creating regions where aquatic organisms cannot survive.

8.6 Thermal Pollution

Effects on Ecosystems:

• Increased water temperatures from thermal pollution lead to decreased dissolved oxygen (DO), affecting respiration in aquatic organisms.

• Altered thermal regimes can disrupt breeding patterns and migratory behavior of fish.

Sources:

• Power plants discharge heated water as part of cooling processes, leading to significant ecological changes in receiving waters.

8.7 Persistent Organic Pollutants (POPs)

Characteristics:

• Synthetic compounds that resist environmental degradation, persisting in ecosystems for decades.

Examples include:

• DDT and PCBs, which have been banned or restricted in many countries due to their harmful effects.

Effects:

• Bioaccumulation in food webs leads to increasing concentrations in higher trophic levels, resulting in long-term health effects in top predators and humans.

8.8 Biomagnification

Definition: Biomagnification refers to the increase in concentration of substances, such as toxins, as they move up the food chain, becoming more concentrated in organisms at higher trophic levels.

Examples of Substances:

• DDT and methylmercury, which affect top predators like eagles, causing reproductive failures and neurological damage.

8.9 Solid Waste Disposal

Types of Solid Waste:

• Municipal solid waste (MSW) includes everyday items discarded by the public, while electronic waste encompasses discarded electrical or electronic devices.

Landfill Characteristics:

• Must-have systems in place for leachate collection, gas collection, and preventing contamination of surrounding environments.

Issues with Landfills:

• Groundwater contamination from leachate, which can be toxic if not managed properly.

• Greenhouse gas emissions, primarily methane, produced during decomposition, contributing to climate change.

8.10 Waste Reduction Strategies

Three Rs: Reduce, Reuse, Recycle.

Recycling:

• Reduces demand for new materials, conserving resources and energy but can be energy-intensive in terms of processing.

Composting:

• Nutrient recycling through the decomposition of organic waste, though it may face issues with odor and pest attraction.

8.11 Sewage Treatment

Treatment Process:

• Primary: Involves physical removal of solids through screening and sedimentation.

• Secondary: Biological breakdown of organic matter by bacteria in aeration tanks.

• Tertiary: Removal of remaining pollutants, often including nutrient removal before discharge into water bodies.

8.12 LD50 & Dose Response Curve

LD50 Definition: The concentration of a substance needed to kill 50% of a given population, a critical measure in toxicology.

Dose Response Curve:

• Illustrates the relationship between toxin exposure and mortality effects, helping to understand the toxicological impact on populations.

8.14 Pollution and Human Health

Key Health Issues:

• There is a well-established link between pollution and various diseases, including dysentery from contaminated water, mesothelioma from asbestos exposure, and respiratory issues caused by air pollutants such as particulate matter and ozone.

8.15 Pathogens and Infectious Diseases

Examples:

• Pathogens such as tuberculosis, malaria, cholera, and emerging viruses like Zika and SARS pose significant public health threats.

• Vectors like mosquitoes and fleas play a crucial role in transmitting these diseases, highlighting the importance of vector control in managing outbreaks.