Global contamination of soil


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Soil is a biologically active, complex mixture of minerals, organic materials, living organisms, air and water.
Soil contamination is the presence of man-made chemicals or other alteration to the natural soil environment.

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Global contamination of soil

  1. 1. Global contamination of soil Presented by Dr. B. Victor., Ph. DEmail : Blog:
  2. 2. “To forget how to tend the soils is toforget ourselves” -Mahatma Gandhi
  3. 3. Presentation outline  Definition of soil  Soil-an introduction.  Human dependence on soil  Soil functions  Components, properties, profile, a nd types of soil.  Soil contamination- definition, causes and effects  Remedial measures  conclusion
  4. 4. Definition of Soil Traditional definition – material which nourishes and supports growing plants. Component definition – mixture of mineral matter, organic matter, water and air. (Example: Loam soil = 45% mineral matter, 5% organic matter, 25% water, and 25% air).
  5. 5. What is soil?Soil is a biologicallyactive, complex mixture ofminerals, organicmaterials, living organisms, airand water.
  6. 6. Soil-an interface system Soil is an interface between biosphere, lithosphere, hydrosphere and atmosphere.
  7. 7. Distribution of land on planet earth Land occupies 38% of the total space. Type of land % composition Agricultural land ~30 % Forests ~30 % Desert 36% Other land 4% (rock etc.)
  8. 8. Basic Soil constituents • Solid phase Mineral matterSoil is a Organic matter three •Liquid phasephase Soil watersystem •Gaseous phase Soil air
  9. 9. Human dependence on soil resource The site for A place for storingAn essential base agricultural and raw materials and of human life forest production wastes A mirror of the A constituent history of element of civilizations and landscape cultures.
  10. 10. Global degradation of soil 95% of human food is derived from the earth. Only 10% of the world’s land area is suitable for growing crops. Soil quality is degrading worldwide.
  11. 11. Unique soil functionsAn essential natural An integrator of all A medium for plant resource. parts of ecosystems. growth A storehouse of A home for A decomposing water, heat and organisms medium for wastes chemicals. A buffer system to A source material for neutralize harsh construction of environmental shelter changes
  12. 12. Soil-an universal ecological system A complex heterogeneous medium A dynamic ecological system The outer most layer of the earth’s crust (Earth’s living skin-1/3 of surface). A complex open process and response system A vital resource that provides food, feed, fuel and fiber
  13. 13. An overview of soil functions
  14. 14. Major components of soil• Soils have four major components:(1) mineral matter,(2) organic matter,(3) air, and(4) water. Mineral matter contains three fractions, sand, silt, and clay. Organic matter contains appreciable quantities of nitrogen, phosphorus and sulfur . Air and water occupy the pore spaces in soils.
  15. 15. Soil volume Soil consists of organic particles and inorganic matter with pore spaces between and within them. Pore spaces contain soil air, and soil solution. In other words, soil volume consists of solid, liquid and gaseous phases.
  16. 16. 5-components of soilSoil component contents/functionsOrganic matter -Dead and decaying plants and animal & animal manure. -Add nutrients to the soil & hold water.-Minerals Inorganic materials composed of sand, silt and clay. -gives texture to soil.Living organisms Variety of organisms aerate, mix and add nutrients to soil.Water Essential nutrient for plantsAir Provides drainage.
  17. 17. Components of soilby proportionOrganisms 10% Roots 10% Humus 80%
  18. 18. Mineral particle size ranges Mineralsand, silt clay. matter Type of mineral Size range particle sand 2.0-0.06mm silt 0.06-0.002mm clay Less than 0.002mm
  19. 19. Soil organic matter Plant debris, animal litter carcasses, excreta Soluble leachates Organic compoundsorganic matter Bacteria roots acetomycetes fungi Soil organisms algae protozoa
  20. 20. Soil water(i.e. water in the soil). Gravitational water: Gravitational water fills all the pore-space, and leaves no room for oxygen and gaseous exchange. Capillary water: This water which is held with the force of surface tension by the soil particles, and is resistant to the forces of gravity. Hygroscopic water: This water is held so tightly (by surface tension) to the soil particles that the plant roots cant take it up.
  21. 21. ‘Big picture’ of soil properties Mineral texture texture Organic texture Micro-aggregates structure Macro-aggregates Micro-porosity Total porosity Meso-porosity Macro-porosity Capillary water Soil water Gravitational water Hygroscopic water
  22. 22. Physical Properties of Soils Soil Texture –the relative proportions of sand, silt, and clay in the soil. e.g. sandy soil, silty soil, and clay soil. Soil Structure – Structure refers to the arrangement of soil particles. E.g., Granular, Platy, Wedge, Blocky, Prismatic, and Columnar. Soil structure is of particular importance in the absorption of water and the circulation of air
  23. 23. Physical properties of soil Soil texture • Sandy soil, clayey soil, loamy soil • Granules, crumbs, columns, prisms, blocks, or Soil structure clusters Water holding • Depends on texture of soil capacity • Clay soil holds more water. • Low pH soils-acidicAcidity/alkalinity • High pH soils-alkaline Consistence • Hard, loose, friable, firm, plastic and sticky color • Dark, yellow, grey hues
  24. 24. Soil Color Color in soils is due primarily to two factors, humus content and the chemical nature of the iron compounds. Chemical Humus nature of content the iron Soil color compounds Humus has a dark brown or black color. Iron is an important color material which stains mineral particles Ferrous oxide gives gray color Ferric oxide gives red color Hydrated ferric oxide gives yellow color
  25. 25. Soil profile Horizon contents O horizon Fungi, animal wastes, leaves and branches, at various levels of decomposition. A Horizon(Topsoil) Partially decomposed matter B Horizon(Subsoil) Few organisms Less organic matter C Horizon partly weathered or decomposed rock. R Horizon the solid rock layer
  26. 26. Soil pH Soil pH is primarily controlled by the concentration of free hydrogen ions in the soil matrix. Acidic soils have a relatively large concentration of hydrogen ions. Alkaline soils have a relatively low concentration of hydrogen ions.
  27. 27. pH and soil fertilitySoil fertility • Soil fertility is directly influenced by pH through the solubility of many nutrients. • At low pH, many nutrients become very Low pH soluble and are readily leached from the soil profile High pH • At high pH, nutrients become insoluble and plants cannot readily extract them. Optimum • Maximum soil fertility occurs in the range pH 6.0 to 7.2
  28. 28. Soil TypesDepending on the size of the particles in the soil, it can be classified as: Sandy soil Silty soil Clay soil Loamy soil Peaty soil Chalky soil
  29. 29. Soil factors influencing plant growth
  30. 30. Soil organismsMicro-biota• Soil algae, bacteria, fungi, protozoansMeso-biota• Nematodes, oligochaetes, insect larvae, collembola.Macro-biota • Earth worms, rats, snakes.
  31. 31. Dependence biota on soil Soil biota depend on the soil environment for their energy and nutrient supply.
  32. 32. Soil contamination Soil contamination is the presence of man-made chemicals or other alteration to the natural soil environment.
  33. 33. The fate of contaminants in soil Contaminants bind tightly to the soil Contaminants evaporate into the air Contaminants end up in soil/ground water.
  34. 34. Common chemicals ofsoil contamination Petroleum Heavy metals hydrocarbons Pesticides Solvents
  35. 35. Sources of soil contaminants Industrial • Active mines pollution • Solid wastes, waste waters • Consumption of fossilOil pollution fuels.Agricultural • Pesticides, fertilizers pollution
  36. 36. Land pollution: sources ofsolid wastes Wastes from agriculture – crop and farm residues, anima manure. Wastes from mining – coal wastes, metal ore wastes. Industrial wastes- solvents chemicals, paints. Solids from sewage treatments-biomass sludge, settled solids. Ashes – residues from solid fuels Carbage – glass, metals, clothes, plastics, wood, papers.
  37. 37. Causes of soil contamination Indiscriminate use of fertilizers Indiscriminate use of pesticides, insecticides and herbicides. Dumping of solid wastes Deforestation and soil erosion Urbanization
  38. 38. Effects of soil contamination
  39. 39. Effects on agriculture Reduced soil fertility Low crop yield Reduced soil biodiversity Reduced nitrogen fixation
  40. 40. Human health effects Exposure to • Nervous system disorders, heavy metals kidney damage, liver toxicity. in soil Exposure to agricultural • Cancer, infertility chemicals Other • Birth defects, nervous system industrial disorders, kidney diseases. toxins
  41. 41. Reducing soil contamination Reduce use of herbicides and pesticides Encourage organic farming. Dispose garbage properly. Recycle garbage. Avoid over packaged items. Utilize natural resources efficiently and reduce wastage.
  42. 42.  Dr.B.Victor is a highly experienced professor, recently retired from the reputed educational institution- St. Xavier’ s College, Palayamkottai, India-627001. He was the dean of sciences, IQAC coordinator and assistant controller of examinations. He has more than 32 years of teaching and research experience He has taught a diversity of courses and guided 12 Ph.D scholars. send your comments to :
  43. 43. Thank you for watching