Water Chemistry and Soil Characteristics

Water Chemistry, Sources, and Soil Characteristics

• Vegetation impacts water chemistry through evaporation, transpiration, decay of organic matter, and selective uptake of ions.
• Anthropogenic impacts on water chemistry include acid rain, landfill leachate, and high nitrite levels from fertilizers.
• Geology affects water chemistry, with about 60% of dissolved material in rivers coming from weathered rock.
• Lake formation can affect water chemistry through dilution and concentration, nutrient input, sedimentation, residence time, water circulation, pH, and alkalinity.
• Water sources include atmospheric water, oceans, inland seas, coastal zones, estuaries, rivers, reservoirs, lakes, wetlands, groundwater, soil water, glaciers, icebergs, and ground ice.
• The global water footprint includes green water, blue water, and grey water footprints.
• Main ions in water include anions and cations, such as chloride, sulphate, hydrogencarbonate, carbonate, calcium, sodium, magnesium, and potassium.
• Biogenous substances in water include silicon, nitrogen, and phosphorus, which are produced by living organisms.
• Soils are composed of minerals, clay, organic matter, and soil colloids, which are characterized by their size, surface area, and charge.
• Histosols are a type of organic soil without permafrost, with little profile development and accumulation of organic matter as the main soil-forming process.
• Peatlands in Indonesia are the largest peat swamp forest in the world and are at risk of land degradation, loss of carbon to the atmosphere, and air pollution due to draining and clearing for agriculture.
• In Malaysia, histosols cover 8% of the land area, mostly in coastal wetlands or just inland for mangroves, with 30% cleared for agriculture.

Soil Acidity, Redox Reactions, and Groundwater Discharge

• Groundwater discharge occurs through evaporation, effluent seepage, groundwater leakage, and abstraction for domestic, industrial, and agricultural use.
• Nitrogen deficiency in soil causes stunted plant growth and chlorosis of older leaves.
• Phosphate rock is a finite resource used 85% for fertilizer, and phosphorus deficiency causes anthocyanin in plants.
• Soil pH affects ion exchange capacity, plant availability of nutrients, and growth of plants and microbes.
• Soil acidification occurs from adding hydrogen ions from acid-forming processes, exchange of 2 hydrogen ions for a calcium ion, and aluminum cations absorbed more strongly than non-acidic cations.
• Acidity and aluminum mobilization occur when adsorbed hydrogen ions attack clay surfaces, releasing structural aluminum cations and exchanging with solution until in equilibrium.
• Acid soils cause aluminum toxicity, which restricts root growth and inhibits nutrient uptake, and molybdenum deficiency restricts symbiotic nitrogen fixation.
• Nitrogen fertilizers and nitrification cause soil acidification through ammonium and oxygen release, which also leaches nitrate and hydrogen ions.
• Acid rain from burning fossil fuels releases sulfur dioxide and nitrogen oxides gases, oxidizing to sulfuric and nitric acid returned to the soil in acid rain and dry deposition.
• Acid sulfate soils cause oxidation reactions when exposed to oxygen, and liming with limestone effectively increases soil pH.
• Determining lime requirement considers pH buffering capacity, initial soil pH and required change, depth of soil to ameliorate, and type of liming material used.
• Redox reactions involve transfer of electrons, with reduction gaining electrons or losing positive charge and oxidation losing electrons or gaining positive charge. Terminal electron acceptors during respiration are oxygen, and organic carbon is oxidized through aerobic respiration.

Soil Acidity, Redox Reactions, and Groundwater Discharge

• Groundwater discharge occurs through evaporation, effluent seepage, groundwater leakage, and abstraction for domestic, industrial, and agricultural use.
• Nitrogen deficiency in soil causes stunted plant growth and chlorosis of older leaves.
• Phosphate rock is a finite resource used 85% for fertilizer, and phosphorus deficiency causes anthocyanin in plants.
• Soil pH affects ion exchange capacity, plant availability of nutrients, and growth of plants and microbes.
• Soil acidification occurs from adding hydrogen ions from acid-forming processes, exchange of 2 hydrogen ions for a calcium ion, and aluminum cations absorbed more strongly than non-acidic cations.
• Acidity and aluminum mobilization occur when adsorbed hydrogen ions attack clay surfaces, releasing structural aluminum cations and exchanging with solution until in equilibrium.
• Acid soils cause aluminum toxicity, which restricts root growth and inhibits nutrient uptake, and molybdenum deficiency restricts symbiotic nitrogen fixation.
• Nitrogen fertilizers and nitrification cause soil acidification through ammonium and oxygen release, which also leaches nitrate and hydrogen ions.
• Acid rain from burning fossil fuels releases sulfur dioxide and nitrogen oxides gases, oxidizing to sulfuric and nitric acid returned to the soil in acid rain and dry deposition.
• Acid sulfate soils cause oxidation reactions when exposed to oxygen, and liming with limestone effectively increases soil pH.
• Determining lime requirement considers pH buffering capacity, initial soil pH and required change, depth of soil to ameliorate, and type of liming material used.
• Redox reactions involve transfer of electrons, with reduction gaining electrons or losing positive charge and oxidation losing electrons or gaining positive charge. Terminal electron acceptors during respiration are oxygen, and organic carbon is oxidized through aerobic respiration.