Water Pollution notes 1

Water Pollution Overview Water pollution refers to the contamination of water bodies such as rivers, lakes, oceans, and groundwater caused by human activities and natural events.

Sources of Water Pollution

  • Point Sources

    • Definition: Point sources are single identifiable sources of pollution.

    • Examples: Smokestacks, waste discharge pipes.

  • Nonpoint Sources

    • Definition: Nonpoint sources are diffuse and difficult to identify.

    • Examples: Urban runoff, pesticide spraying.

Eutrophication

  • Process: Nutrient enrichment of water bodies leading to algal blooms.

  • Biological Oxygen Demand (B.O.D): Refers to the amount of oxygen required by microbes to decompose organic material in water, indicating pollution levels.

  • Key Nutrients:

    • Nitrates (NO3-), Phosphates (PO4-), Potassium (K+).

  • Effects of Eutrophication:

    • Leads to decreased dissolved oxygen (D.O), causing fish and aquatic organism die-offs.

    • Hypoxic (low oxygen) and anoxic (no oxygen) conditions are created, particularly due to agricultural runoff and wastewater discharge.

    • Example: Gulf of Mexico suffers from eutrophication due to excess fertilizers from Mississippi River runoff.

Sources of Pollution

  • Animal Wastewater:

    • Concentrated Animal Feeding Operations (CAFOs) produce significant waste.

    • Manure lagoons: Large ponds to prevent manure leaking into groundwater, used as fertilizers after breakdown by bacteria.

Tolerance Levels of Organisms

  • Different organisms have varying tolerance levels for pollutants.

  • Oxygen Sag Curve: Illustrates how types of organisms present vary with changes in oxygen levels due to pollution.

    • Clean water organisms: Trout, perch.

    • Trash fish: Carp, leeches.

Indicator Species

  • Organisms that indicate the health of an ecosystem.

  • Case Study: Residents in Ohio cautioned against tap water use due to toxins released by blue-green algae in Lake Erie.

    • Main cause of blooms: Phosphorus from agricultural runoff.

Oligotrophic vs. Eutrophic Lakes

  • Oligotrophic Lakes

    • Characteristics: Low nutrient amounts, stable algae populations, high dissolved oxygen.

  • Eutrophic Lakes

    • Characteristics: High nutrient levels, frequent algal blooms, lower dissolved oxygen.

Temperature and Oxygen Solubility

  • As water temperature increases, solubility of oxygen decreases.

  • Thermal Pollution: Results from heat released into water, negatively impacting organisms.

    • Warm water has less oxygen for respiration compared to colder water.

Urban Runoff Mitigation Strategies

  • Methods:

    • Increase infiltration (permeable pavement, planting trees).

    • Promote public transport to decrease car dependency.

    • Sustainable urban planning (building up instead of out).

Persistent Organic Pollutants (POPs)

  • Definition: Synthetic, carbon-based molecules that do not break down easily.

  • Examples: DDT, PCBs.

  • Characteristics: Toxic to organisms, accumulate in fatty tissues, and can travel long distances.

  • Case Study: DDT's persistence and bioaccumulation leads to environmental concerns and health issues for top predators.

Bioaccumulation and Biomagnification

  • Bioaccumulation: The process where organisms selectively absorb and concentrate pollutants.

    • Example: Mercury accumulation in organisms.

  • Biomagnification: Increase in concentration of substances as they move up the food chain, particularly affecting top predators.

    • Effects: Reproductive, nervous, and circulatory system issues in humans and wildlife due to increased concentration of pollutants like DDT and mercury.

The Endocrine System

  • Role: Maintains homeostasis in response to environmental changes through hormone regulation.

  • Endocrine disruptors can interfere with this system leading to developmental problems in various species.

    • Chemicals of concern: PCBs, dioxins, pesticides, and others that can affect bodily functions.

Lethal Dose (LD50)

  • Definition: The dose of a chemical lethal to 50% of a specific population.

  • Dose-Response Curve: Graph indicating the relationship between the dose of a toxin and the mortality rate of a population.

  • Male fish are increasingly showing signs of feminization due to pollutants affecting hormonal functions in waterways.