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Environmental Chemistry

Environmental Chemistry. IB Option E Part 4: Soil & Waste. Soil Degradation. Soil quality has been altered in such a way that it lowers crop production. Can be caused by changing weather patterns, or by anthropogenic factors such as acidification contamination erosion salinization

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Environmental Chemistry

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  1. Environmental Chemistry IB Option EPart 4: Soil & Waste

  2. Soil Degradation • Soil quality has been altered in such a way that it lowers crop production. • Can be caused by changing weather patterns, or by anthropogenic factors such as • acidification • contamination • erosion • salinization • from industrialization, irrigation, overgrazing, overharvesting of trees

  3. Salinization • from constant or excess irrigation. • Salts from irrigated water accumulate in soil long after the water evaporates. • Plants die from toxic levels of salt or inability to take up water from salty soil with their roots.

  4. Nutrient depletion • intensive farming – • no time for fields to be fallow; • no organic fertilizers used

  5. Soil pollution • can be caused by • industrial discharge • use of pesticides and fertilizers • illegal dumping of spent engine oil, etc. • all lead to groundwater pollution.

  6. Soil Organic Matter (SOM) • organic constituents of the soil • Biological – humus provides source of energy and source of essential nutrient elements nitrogen, phosphorus and sulfur to sustain healthy growth.

  7. Soil Organic Matter (SOM) • organic constituents of the soil • Physical – humus helps soil retain moisture; dark color of humus absorbs heat.

  8. Soil Organic Matter (SOM) • organic constituents of the soil • Chemical– humus acts like clay with its cation exchange capacity. Contains active sites which enable it to bind to nutrient cations. Also acts as acid-base buffer.

  9. Common organic soil pollutants • Hydrocarbons and other VOCs • Pesticides, herbicides & fungicides • Polyaromatic hydrocarbons (PAHs) • Polychlorinated biphenyls (PCBs)

  10. Table 7: Methods of Waste Disposal

  11. Table 8: Recycling

  12. Table 9: Plastics Recycling Codes (no need to memorize, just an “FYI” item)

  13. Table 10: Nuclear Waste

  14. Water and Soil • Precipitation of heavy metal ions and phosphates from water • When a salt is labeled “insoluble,” it really means that it has a very low/slight solubility in water. MX(s) M+(aq) + X-(aq)

  15. Water and Soil • Precipitation of heavy metal ions and phosphates from water • When a salt is labeled “insoluble,” it really means that it has a very low/slight solubility in water. • Solubility product, ksp=[M+][X-]

  16. Water and Soil • Many metal sulfides have very low solubility products, but can still be precipitated out by bubbling other compounds through the water, making use of the common ion effect.

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