mass of theatmosphere:5 x 1018 kg

mass of theatmosphere:5 x 1018 kg

1 ppm of this is5 x 1012 kg

Tis is5 x 109 tonnesOr: 5 billion tonnesOr: 5000 million tonnes

Salt water Oceans – (contain ~97% of all water on earth; also responsible for weather, redistribution of energy)

Fresh water Polar ice caps, glaciers, Lakes, streams, ground water, soil water

Brackish water Water whose salinity is intermediate between that of fresh water and salt water

Soil W ater

In term edia te zone Aeration zone

------------------------- 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 farmers2 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 theGREEN 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 food37% of Earth’s land produces food

Total surface area of earth 5.1 1014 m2

Land 25% 1.3 1014 m2 13 Gha 10% 4.8 Gha

(1 hm = 102 m; 1 ha = 1 hm2 = 104 m2)

pastures: 3.3 Ghacropland: 1.5 Gha

A rab lelan d11 %

(1 .4 4 b illio nhec ta re s)

O the r land33 %

(4 .3 5 b illio nhec ta re s)

a

F orest and w ood land30 %

(3 .8 9 b illio nhec ta re s)

P e rm an en tm eado w s & p astu re s

26 %(3 .3 6 b illio n

hec ta re s)

17 % o f a rab le landis irriga ted(2 40 m illion h ec tare s)

The Earth's LandTotal Area: 13 Billion Hectares

Other land" includes barren and developed land.

Source: Food and Agriculture Organizationfrom Committee for the National Institute for the Environment

http://www.cnie.org/pop/conserving/landuse2.htm

[1] development of high yield strains of grains

[2] increased use of inorganic fertilizers[3] irrigation[4] synthetic pesticide use

The green revolution:

increase productioneliminate competition

3 times more foodbeing produced

then in 1950

Are thereany

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 hydrocarbonsolvents

4. high toxicity to tissues

5. relatively low toxicity to humans

The idea ofBIOMAGNIFICATION

Fish are living separatory funnels

They ingest water containing DDT

The DDT dissolves in the fatty tissues of their bodies

Biomagnificationin Long Island Sound

[DDT] in sea water 0.000003 ppm

[DDT] in plankton 0.04 ppm

[DDT] in minnows 0.5 ppm

[DDT] in needle fish 2 ppm

[DDT] in cormorants 25 ppm

© 2012 W. H. Freeman & Co.

© 2012 W. H. Freeman & Co.

© 2012 W. H. Freeman & Co.

LD50

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. LD50 = (mass of DDT in rats) # Kg of rat

© 2012 W. H. Freeman & Co.

© 2012 W. H. Freeman & Co.

© 2012 W. H. Freeman & Co.

© 2012 W. H. Freeman & Co.