apes unit 4 (kortum)

Human Nutrition

• Undernutrition: Not enough calories to meet daily energy needs.

• Malnutrition: Lack of specific nutrients (vitamins, protein, minerals).

• Overnutrition: Too many calories; leads to obesity and health problems.

Why World Hunger Still Exists

• Poverty and unequal food distribution

• Food waste

• Political instability and conflict

• Climate impacts on crops

• Lack of infrastructure and storage

Who Has Access to Meat?

• Mostly wealthier populations in developed countries.

• Meat requires large energy subsidies, land, and water.

Energy Subsidy

• Ratio of energy input (fuel, fertilizers, labor) to energy output (food calories).

• Industrial agriculture usually has a high energy subsidy.

Industrial Agriculture

• Large monocultures

• Heavy fertilizer & pesticide use

• High yields but environmental damage

Sustainable Agriculture

• Smaller scale, more biodiversity

• Less chemical use

• Practices that maintain soil health

Green Revolution

Mid-1900s increase in food production. included high-yield corp, synthetic fertilizer

Flood irrigation

• Water floods fields

• ~20% efficient (lots of evaporation)

Furrow irrigation

• Water flows through trenches

• ~60% efficient

Spray irrigation

• Sprinkler systems

• ~75% efficient

Drip irrigation

• Water directly to roots

• ~95% efficient (most efficient)

Waterlogging

Soil becomes saturated with water → roots suffocate.

Salinization

Salt buildup from irrigation water evaporation

Soil Erosion

Soil carried away by wind or water

Solutions

• Drip irrigation

• Better drainage

• Windbreaks

• Contour plowing

• No-till farming

Organic Fertilizer

Pros:

• Improves soil structure

• Slow nutrient release

Cons:

• Lower nutrient concentration

Synthetic Fertilizer

Examples:

• Nitrogen, phosphorus fertilizers

Pros:

• Immediate nutrient availability

• Higher yields

Cons:

• Runoff causes eutrophication

• Soil degradation

Monocropping

• Growing one crop repeatedly.

Pros:

• Efficient for machinery.

Cons:

• Soil nutrient depletion

• Pest vulnerability.

Polycropping

• Multiple crops grown together.

Pros:

• Reduces pests

• Improves soil nutrients

• Higher biodiversity

Pesticides

Pros:

• Increase crop yields

Cons:

• Kill non-target species

• Bioaccumulation/biomagnification

• Pest resistance

Pesticide Treadmill

Pests develop resistance → stronger chemicals needed → cycle repeats.

Integrated Pest Management (IPM)

Uses multiple strategies:

• Biological controls (predators)

• Crop rotation

• Limited pesticide use

• Monitoring pest populations

GMOs (Genetically Modified Organisms)

• Organisms whose DNA has been altered using genetic engineering.

Examples:

• Bt corn

• Herbicide-resistant soybeans

• Golden rice

Pros:

• Increased yield

• Pest resistance

• Improved nutrition

Cons:

• Potential ecological impacts

• Cross-pollination with wild plants

• Ethical concerns

CAFOs (Concentrated Animal Feeding Operations)

• Large industrial livestock facilities.

Pros:

• Efficient meat production

• Lower food cost

Cons:

• Water pollution from manure

• Antibiotic resistance

• Animal welfare concerns

Current Fishing Methods

• Trawling

• Longlining

• Purse seining

• Drift nets

Overfishing Problems

• Fish population collapse

• Ecosystem imbalance

• Bycatch (unwanted species caught)

Sustainable Fishing Methods

• Catch limits

• Marine protected areas

• Selective fishing gear

• Aquaculture

Aquaculture

• Farming fish or aquatic organisms.

Pros:

• Reduces pressure on wild fish populations

Cons:

• Waste pollution

• Disease spread

• Escape of farmed species

Soil Conservation Practices

• Intercropping: growing crops together for pest reduction

• Crop rotation: alternating crops each season

• Agroforestry: trees mixed with crops

• Contour plowing: plowing along land contours to prevent erosion

• No-till agriculture: planting without disturbing soil

Desertification

Land becomes desert due to overgrazing, deforestation, or poor farming.

Point Source Pollution

Single identifiable source (pipe, factory discharge)

Nonpoint Source Pollution

Diffuse sources (agricultural runoff, urban runoff)

BOD (Biological Oxygen Demand)

• Amount of oxygen microorganisms need to decompose organic waste.

High BOD → low dissolved oxygen → fish die.

Nutrient Runoff & Eutrophication

• Fertilizer runoff adds nitrogen and phosphorus.

• Algae bloom forms.

• Algae die.

• Decomposition consumes oxygen.

• Hypoxia (low oxygen)

Dead Zones

Areas with little oxygen where aquatic life cannot survive.

Primary Treatment Wastewater

• Physical removal of solids

• Screening & sedimentation

Secondary Treatment Wastewater

Bacteria break down organic matter

Tertiary Treatment

• Removes nutrients and chemicals

Removes:

• Solids

• Organic waste

• Some pathogens

Does NOT fully remove:

• Pharmaceuticals

• Hormones

• Some heavy metals

Septic Tanks

Parts:

• Tank

• Drain field (leach field)

Process:

1. Waste enters tank

2. Solids settle

3. Bacteria decompose waste

4. Liquid drains into soil

Pathogen Pollution

Sources:

• Human sewage

• Livestock waste

• Wildlife

Consequences:

• Waterborne diseases

• Unsafe drinking water

Heavy Metals

Examples:

• Lead

• Mercury

• Arsenic

Problems:

• Toxic even in small amounts

• Bioaccumulation

• Biomagnification

Pharmaceuticals & Hormones

Sources:

• Human medications

• Livestock hormones

Examples:

• Birth control hormones

Problems:

• Endocrine disruption

• Fish reproductive abnormalities

Oil Pollution

Sources:

• Tanker spills

• Offshore drilling

• Urban runoff

Consequences:

• Smothers marine life

• Toxic to organisms

Solutions:

• Containment booms

• Skimmers

• Bioremediation

Solid Waste Pollution (Plastics)

Sources:

• Consumer waste

• Fishing gear

• Microplastics

Consequences:

• Wildlife ingestion

• Ocean garbage patches

• Chemical contamination

Turbidity

• Cloudiness in water caused by suspended particles.

Effects:

• Reduces light penetration

• Harms aquatic plants and fish

Thermal Pollution

• Discharge of warm water (often from power plants).

Effects:

• Decreases dissolved oxygen

• Stresses aquatic life

Recovery Curve

• Stream gradually returns to normal temperature downstream.

Clean Water Act (1972)

• Regulates pollutant discharge into U.S. waters.

• Protects surface waters.

Safe Drinking Water Act (1974)

• Protects public drinking water supplies.

• Sets contaminant standards.