mass of the atmosphere: 5 x kg

mass of the atmosphere: 5 x kg 1 ppm of this is 5 x kg Tis is 5 x 10 9 tonnes Or: 5 billion tonnes Or: 5000 million tonnes

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 2 and the poor. 3 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.

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)

Pesticides and the GREEN REVOLUTION can we feed the planet? Since 1950 food grew faster than population: population growth:1.7% per year food growth: 3% per year land growth: 0% per year

10% of Earth’s surface produces food 37% of Earth’s land produces food Total surface area of earth  5.1  m 2 Land  25%  1.3  m 2  13 Gha 10%  4.8 Gha (1 hm = 10 2 m; 1 ha = 1 hm 2 = 10 4 m 2 ) pastures: 3.3 Gha cropland:1.5 Gha

The Earth's Land Total Area: 13 Billion Hectares Other land" includes barren and developed land. Source: Food and Agriculture Organization from Committee for the National Institute for the Environment

[1]development of high yield strains of grains [2]increased use of inorganic fertilizers [3]irrigation [4]synthetic pesticide use The green revolution: increase production eliminate competition

3 times more food being produced then in 1950 Are there any environmental impacts?

Metabolic breakdown product, DDE:

Properties of DDT and other organic compounds 1. very stable 2. low stability in water 3. high stability in hydrocarbon solvents 4. high toxicity to tissues 5. relatively low toxicity to humans

The idea of BIOMAGNIFICATION

Fish are living separatory funnels They ingest water containing DDT The DDT dissolves in the fatty tissues of their bodies

Biomagnification in Long Island Sound [DDT] in sea water ppm [DDT] in plankton0.04 ppm [DDT] in minnows0.5 ppm [DDT] in needle fish2 ppm [DDT] in cormorants25 ppm

© 2012 W. H. Freeman & Co.

LD 50 A measure of toxicity 1. Feed DDT to rats (spike their food) 2. Continue upping their dose until half of the die 3. Measure concentration of DDT in the rats 4. LD 50 = (mass of DDT in rats) # Kg of rat

© 2012 W. H. Freeman & Co.