Salt water Oceans – (contain ~97% of all water on earth; also responsible for weather, redistribution of energy) Fresh waterPolar ice caps, glaciers, Lakes, streams, ground water, soil water Brackish waterWater whose salinity is intermediate between that of fresh water and salt water

water table Zone of saturation (or ground water zone)

The Green Revolution -- based on modern, high yielding plant varieties, requiring high inputs of fertilizer and water -- has led to increases in world food production at a pace that outstripped population growth. Food prices have declined markedly. Increased water use in irrigated agriculture has benefited farmers and the poor. But increased water and chemical use that fueled the Green Revolution has contributed to environmental degradation, and threatened the resource base upon which we depend for food and livelihoods.

1 kg of beef requires 15,000 kg of water

Molarity = Moles of solute/Liters of Solution (M) Molality = Moles of solute/Kg of Solvent (m) Mole Fraction = Moles solute/total number of moles Mass % = Mass solute/total mass x 100 Volume % = volume solute/total volume x 100 ppm = parts per million * ppb = parts per billion * Chemical concentrations * mass for solutions, volume for gasses

Molarity = Moles of solute/Liters of Solution (M) Molality = Moles of solute/Kg of Solvent (m) Mole Fraction = Moles solute/total number of moles Mass % = Mass solute/total mass x 100 Volume % = volume solute/total volume x 100 ppm = parts per million * ppb = parts per billion * Chemical concentrations * mass for solutions, volume for gasses

Molarity = Moles of solute/Liters of Solution (M) Molality = Moles of solute/Kg of Solvent (m) Mole Fraction = Moles solute/total number of moles Mass % = Mass solute/total mass x 100 Volume % = volume solute/total volume x 100 ppm = parts per million * ppb = parts per billion * Chemical concentrations * mass for solutions, volume for gasses

Assuming the density of water to be 1 g/mL we approximate the density of a dilute aqueous solution to be 1 g/mL  1 ppm = 1 μg/mL = 1 mg/L  1 ppb = 1 ng/mL = 1 μg/L

Determine the ppm of a NaCl solution if 58.5 grams of NaCl was dissolved in 50.0 ml of water (assume the density of water to be 1 g/ml) Convert ml of water to grams Determine total mass of solution Mass of solution = mass of solute + mass of solvent = = g Apply the definition of ppm 58.5 (10 6 ) / = 5.39 x 10 5 ppm NaCl

Contaminants in Ground Water Organic: Chlorinated solvents Pesticides BTX component of gasoline MTBE component of gasoline Inorganic: Nitrates (animal waste, fertilizers, atmospheric deposition, sewage) Phosphates (detergents, fertilizers, sewage) Biological: Bacteria (e.g., E. coli)