L6. Environmental soil and the analysis_Part 1 (1)

Environmental Soil and Analysis

Lecture Overview

  • Instructor: Huiyuan Guo, Ph.D., Assistant Professor, Department of Chemistry

  • Lecture Content: Focuses on the analysis of environmental soil, covering various aspects such as formation, components, and pollution.

4. Environmental Soil Analysis

4.1 Definition, Function, and Formation of the Soil

  • Definition: Soil is the unconsolidated mineral or organic material on the earth's surface, serving as a natural medium for plant growth (Soil Science Society of America).

  • Functions of Soil:

    • Provides habitats for soil organisms.

    • Supplies nutrients essential for plant growth.

    • Acts as a filter or sink for pollutants.

4.2 Components in the Soil

  • Soil Composition:

    • Atmosphere: Soil air.

    • Rocks and Minerals: Make up mineral constituents.

    • Biosphere: Biomass contributing organic matter.

    • Hydrosphere: Soil water.

4.3 Soil Pollution

  • Definition: Soil pollution is often subtle but has severe impacts. Contaminants can leach into groundwater and affect crops, leading to exposure for humans and animals.

4.4 Analytical Methods for Soil Analysis

  • Measurement Techniques:

    • Gravimetric and volumetric methods for determining soil water content.

    • Calculation formulas for determining various soil characteristics such as bulk density and pore space.

Example Calculations

Soil Core Analysis:

  • Example Question: Given a soil core with specific dimensions, calculate gravimetric soil water content, volumetric soil water content, soil bulk density, % pore space, % water-filled, and % air-filled pore space.

  • Key Metrics:

    • Density of water: 0.997 g/cm³

    • Volume of soil core calculated using the formula for volume of a cylinder.

4.5 Soil Formation

Processes of Soil Formation

  • Stages:

    • Begins with parent material, either consolidated bedrock or unconsolidated deposits (e.g. glacial drift).

    • Physical weathering reduces particle size with minimal chemical changes.

    • Chemical/biological weathering leads to secondary mineral formation and incorporation of organic matter.

4.6 Soil Minerals

Primary Soil Minerals

  • Derived from the rocks of parent material. Dominated by silicates based on the SiO4 tetrahedron.

Secondary Soil Minerals

  • Formed by weathering processes acting on primary minerals. Notable groups: aluminosilicate clay minerals, hydrous oxides.

4.7 Soil Organic Matter (SOM)

Formation of SOM

  • Pathways:

    1. Decomposed material releases compounds that polymerize to form SOM.

    2. Resistant organic materials further react with low-molecular weight compounds.

  • Types of SOM: Humin (high molecular weight), humic acids, and fulvic acids (low molecular weight).

4.8 Soil Pollution Regulations

Legal Framework

  • Superfund Act (1983): Established to manage cleanup of contaminated sites. Enables taxes to aid remediation efforts.

Conclusion

  • Learning Expectations: Comprehensive understanding of soil's functions, components, and pollution. Reading assignments and practice questions will further reinforce the material covered.