Enviornment -BSCUV101 Soil Pollution lecture notes KVB

Page 1: What is Soil?

Definition of Soil

  • Soil is a thin covering over land that supports plant life.

  • Composed of a mixture of:

    • Minerals

    • Organic material

    • Living organisms

    • Air

    • Water

Formation of Soil

  • Factors contributing to soil formation from parent material include:

    • Mechanical weathering: caused by temperature changes and abrasion.

    • Natural elements: wind, moving water, glaciers.

    • Chemical weathering activities: carried out by lichens.

  • Climate and time play crucial roles in soil development:

    • Dry/cold climates develop soil slowly.

    • Warm/humid climates develop soil rapidly.

  • Example of soil formation timeline:

    • Ideal conditions: soft parent material → 1 cm of soil in 15 years.

    • Poor conditions: hard parent material → hundreds of years to form.

Page 2: Structure of Soil

Soil Layers

  • O horizon:

    • Composed of freshly fallen and partially decomposed organic materials.

    • Typically brown or black.

  • A horizon:

    • Contains partially decomposed organic matter (humus) and inorganic particles.

    • Darker and looser than deeper layers.

    • Roots of most plants are found here.

    • Retains water for gradual release.

  • B horizon: (Subsoil)

    • Contains less organic matter than A horizon.

  • C horizon:

    • Composed of weathered parent material, lacking organic materials.

    • Its chemical composition influences soil pH, water absorption, and retention.

Page 3: Causes of Soil Degradation

Key Causes

  • Erosion: Movement of surface litter and topsoil.

  • Use of fertilizers and pesticides: Excessive application can lead to degradation.

  • Salt in water: High levels affect plant growth.

Impact of Erosion

  • Natural process enhanced by human activities (farming, construction, overgrazing, deforestation).

  • Loss of topsoil reduces soil fertility and water retention.

  • Eroded topsoil contributes to water pollution:

    • Clogs lakes

    • Increases water turbidity

    • Harms aquatic life.

  • Formation of 1 inch of topsoil can take 200-1000 years based on conditions.

  • Non-renewable resource concern: faster erosion than formation necessitates conservation measures.

Conservation Techniques

  • Utilize integrated methods to prevent erosion.

  • Techniques include:

    • Area treatment: treating land to reduce erosion.

    • Drainage line treatment: managing natural water courses.

Page 4: Types of Erosion

Various Erosion Types

  • Common types include:

    • Rill Erosion

    • Inter-rill Erosion

    • Splash Erosion

    • Sheet Erosion

    • Gully Erosion

    • Deep Gully Erosion

    • Stream Bank Erosion

    • Tunnel Erosion

    • Waterfall Erosion

    • Landslide Erosion

    • Coastal Erosion

    • Ravine Erosion

    • Impact of drought on soil.

Page 5: Area Treatment Measures

Purpose and Effects

  • Purpose: Reduce impact of rain on soil.

  • Measures Include:

    • Developing vegetative cover on non-arable land.

    • Implementing water infiltration measures where necessary.

    • Constructing bunds and ponds to store rainwater and recharge groundwater.

    • Ridge to valley sequencing: treating upper catchments first for economic viability and reducing damage risk.

Page 6: Drainage Line Treatment Measures

Purpose and Effects

  • Purpose: Stop deepening of gullies and retain groundwater.

  • Treatment Measures:

    • Plugging gullies at formation to prevent erosion.

    • Creating barriers in natural water courses.

    • Using local materials and skills to reduce costs.

  • Effect: Delayed flow improves groundwater recharge and decreases sedimentation in storage basins.

Page 7: Contour Trenches for Conservation

Overview

  • Gradonies: Trenches with bunds built along contours.

    • Collect run-off and conserve moisture for crops.

    • Beneficial in areas of low to moderate rainfall.

  • Stabilization: Bunds stabilized by fast-growing trees and grasses.

  • Continuous contour benches: Used on steep slopes where bunds are impractical.

Page 8: Check Dams and Erosion Control

Types of Check Dams

  • Live check dams: Barriers from grass, shrubs, and trees across gullies.

  • Earthen checkbund: Built from local soil to check erosion.

  • Gabion structures: Stone structures wrapped in chainlink for water retention and erosion control.

  • Underground bandhara: Underground structures to control groundwater movement.

Page 9: Fertilizer and Pesticides Usage

Key Points

  • Fertilizer: 25% of global crop yield linked to chemical fertilizers.

  • Three primary macronutrients:

    • Potassium (K), Phosphorus (P), Nitrogen (N).

  • Micronutrients: Small amounts needed (e.g., Boron, Zinc, Manganese).

  • Benefits of fertilizers: Restore nutrients emptied by harvesting.

Pesticides

  • Used to control various unwanted organisms.

Page 10: Problems with Pesticide Use

Negative Impacts

  • Pesticides affect humans and a variety of living organisms.

  • Types:

    • Persistent (long-lasting) and non-persistent (break down quickly).

  • Pesticide resistance issues; e.g., DDT effectiveness loss in mosquitoes over time.

DDT Usage

  • One of the first synthetic insecticides, saving lives in the early years.

  • Examples of DDT's persistence in the environment.

Page 11: Environmental Persistence of Pesticides

DDT Half-Life

  • Varies based on soil type, temperature, and organisms present.

  • Usage in agriculture is banned; continues in mosquito control.

  • Attached to soil particles, easily transported by wind and water.

Page 12: Bioaccumulation and Biomagnification

Concepts

  • Bioaccumulation: Toxins accumulate in animals unable to flush them out.

  • Biomagnification: Increasing toxin concentrations in higher trophic levels.

  • Case study: DDT's effect on eggshell strength in birds.

Page 13: Resistance and Population Dynamics

Issues with Pesticides

  • Insect populations can develop resistance, negating pesticide effects.

  • Pesticides kill beneficial species, disrupting natural ecosystems.

Human Health Risks

  • Long-term exposure leads to potential health issues (mutations, cancers).

Reasons for Continued Pesticide Use

  1. Increased food production in the short term.

  2. Economic considerations: yields offset costs.

  3. Health concerns in developing countries drive necessity.

Page 14: Organic Farming

Sustainable Practices

  • Avoid chemical fertilizers/pesticides to minimize negative impacts.

  • Crop rotation enhances soil health and fertility.

  • Debate on effectiveness and economic viability in organic farming.

Alternative Practices

  • Sustainable agriculture: Maintain ecosystem health while producing food.

Page 15: Integrated Pest Management (IPM)

Technique Overview

  • Comprehensive understanding of crop ecology and pests for effective control.

  • Promotion of biopesticides derived from microbial, botanical, and biochemical sources.

Page 16: Salinization and its Effects

Impact of Salinization

  • Results from irrigated land accumulating dissolved salts.

  • Over time, salt can stunt growth and degrade soil quality.

Flushing Salts

  • More water usage can help flush out excess salts from soil.

Page 17: Water Quality Parameters

Quality Parameters Table

  • Various classes of water quality based on parameters such as EC, sodium percentage, sodium absorption ratio, etc.

Page 18: Irrigation Issues

Challenges with Irrigation

  • Overuse leads to increased salinity and water logging issues.

  • Sustainable practices are essential to prevent water salinity.

Page 19: Pollution from Organic Wastes

Impact on Water Quality

  • Sewage increases organic waste concentration, lowering dissolved oxygen.

  • Bacterial activity depletes oxygen in water, causing the formation of anoxic zones.

Page 20: Control Measures for Pollution

Sewage Treatment

  • Introduction of treatment plants to reduce biological oxygen demand (BOD).

  • Implementation of various treatment stages depending on effluent quality.