Human Impact on the Environment

Air Pollution

Types of pollution include air, land, noise, water, and light pollution.
Air pollution is caused by the release of chemicals into the air through harmful gases, burning of fuels, and other byproducts of modern human life.
Polluted air can impede breathing and cause serious diseases in humans and animals.

Land Pollution

Waste materials produced by humans accumulate on the Earth's surface, leading to land pollution.
Chemicals like pesticides and fertilizers are absorbed into the soil, causing contamination.
Ingestion of waste can injure or poison animals. Chemicals can enter the soil and be absorbed by plants or leach into the water supply.

Noise Pollution

Humans produce excessive amounts of loud noise from industrial and vehicle sources.
Excessive noise can interfere with animal communication and harm animals that rely on sound for navigation or hunting.

Water Pollution

Toxins from human and industrial waste are introduced into water supplies, causing water pollution.
Water can be a medium for many pathogens, causing disease when consumed by humans and animals.

Light Pollution

Humans produce excessive amounts of artificial light, interfering with natural cycles of light and darkness.
Artificial light can confuse nocturnal animals and those that hunt at night or rely on the stars for navigation.

The Anthropocene

Scientists agree that many parameters of the Earth system have changed because of human activity.
In the 1980s and 1990s, scientists noticed the Earth was moving away from equilibrium.
Research showed major changes starting after World War II, referred to as “The Great Acceleration.”

Earth System Trends

Trends are shown in graphs displaying changes since 1750 for various parameters:
- Atmospheric carbon dioxide concentration (ppm)
- Stratospheric ozone (% loss)
- Marine fish capture (million tonnes)
- Tropical forest loss (% loss)
- Atmospheric nitrous oxide concentration (ppb)
- Atmospheric methane concentration (ppb)
- Surface temperature anomaly (°C)
- Ocean acidification (hydrogen ion, nmol kg⁻¹)
- Nitrogen to coastal zone (Human N flux, Mtons yr⁻¹)
- Domesticated land (% of total land area)
- Terrestrial biosphere degradation (% decr. mean species abundance)
- Shrimp aquaculture (million tonnes)

CO₂ Emissions per Capita (2006)

CO₂ emissions per capita are categorized into different ranges:
- <2.1 t
- 2.1-4.8t
- >4.8-8.3t
- >8.3-15.8t
- >15.8 t

Geological Time Scale

The Pleistocene epoch lasted for 2 million years.
The Holocene epoch has been ongoing for 11,300 years.
Key geological divisions:
- Era: Cenozoic, Mesozoic
- Period: Quaternary, Neogene, Paleogene, Cretaceous, Jurassic, Triassic, Permian
- Epoch: Holocene, Pleistocene, Pliocene, Miocene, Oligocene, Eocene, Paleocene
Significant boundaries: K/Pg Boundary (visible difference in sediments).

Human Effect on Water Quality

Water Quality: The chemical, biological, and physical status of a body of water.

Importance of Water Quality

Water quality characteristics include:
- Amount of oxygen and nutrients.
- Type and number of organisms.
- Amount of sediment.
These characteristics are crucial for the health of aquatic organisms.

Factors Affecting Water Quality

Natural processes: Seasonal temperature changes and weathering of rock and soil.
Human activities: Pollution from factories and automobiles, deforestation leading to soil erosion.

Runoff

Runoff: Water flow over the land surface carrying soil and contaminants into water bodies.

Point-Source vs Nonpoint-Source Pollution

Point-Source Pollution

Definition: Pollution traced to one specific location.
Examples: Drainpipe, smokestack from a factory, sewage treatment plants.

Nonpoint-Source Pollution

Definition: Pollution that cannot be traced to one specific location; randomness.
Examples: Runoff from lawns, roads, and urban areas.
Runoff contains natural and human-made pollutants like sediments, fertilizers, and oil.

Impact of Pollution

Both point-source and nonpoint-source pollution lower the quality of water.
Most water pollution is from nonpoint-source pollution.
Nonpoint-source pollution can affect drinking water.
Poor water quality harms aquatic organisms. Certain fish can become dangerous to eat due to high toxin levels.

Biomagnification

A process where toxins accumulate in higher concentrations in organisms at higher trophic levels.

Tests for Water Quality

Five main tests for water quality:
- Dissolved oxygen
- Water temperature
- Nitrates
- Acidity
- Turbidity

Dissolved Oxygen

Oceans and lakes contain dissolved oxygen, essential for aquatic life.
Depletion of oxygen levels can lead to:
- Release of excess nitrogen and phosphorus.
- Overgrowth of algae.
- Algae consuming oxygen and blocking sunlight.
- Fish die-offs.

Water Temperature

Aquatic organisms, especially coral reefs, are sensitive to temperature changes.
Coral bleaching occurs due to stress from increased water temperature and ultraviolet radiation, potentially leading to death even with a $2°C$ increase.
As water temperature rises, the amount of oxygen that can dissolve in the water decreases.

Nitrates

Nitrates are nitrogen-based compounds often used in fertilizers.
Runoff of nitrates causes high concentrations in water.
This leads to a rapid increase in algae populations, ultimately reducing oxygen levels.

Acidity

Long-term changes in acidity can alter an entire ecosystem.
Some fish cannot survive acidic conditions, leading to starvation due to the loss of food resources.

Turbidity

Turbidity measures the cloudiness of water from sediments, microscopic organisms, or pollutants.
Greater turbidity reduces the ability of light to pass through the water.
This affects producers that need light for photosynthesis and filter-feeding organisms whose structures can get clogged with sediment.
Measurement: A Secchi disk is used to measure turbidity by lowering it into the water until it is no longer visible; that depth is recorded.

Bioindicator

Bioindicator: An organism sensitive to environmental conditions and one of the first to respond to changes.
Alerts scientists to variations in oxygen levels, nutrients, or pollutants.
Example: Stoneflies indicate good water quality because they cannot survive in low oxygen conditions.
Larger organisms, including fish can also be used as bioindicators; the absence of intolerant fish species indicates low water quality.

Remote Sensing

Remote sensing: Collecting data from a distance, such as through photos from the air or images from satellites.
Used to monitor changes in water storage and forest loss.
Satellite images can be used to compare water conditions over time and monitor changes like forest loss (e.g., Rondonia, Brazil).