Transcript Unit 19 web

19. Food Production
supplementary
ie. (mostly)not in text, but see:
sec.14.10,14.11, 14.12(4th ed.)
Feeding the World
Population:
1965 - 3.5 billion
2000 - 6.0 billion
2050 ~10.0 billion (est.)
1998(millions): 137 born - 53 die = 84 gain (rising)
Average life expectancy = ~65 years
Earth's population growing >1.5%/yr
(NA=0.8%, Malaysia=2.3%)
1 bl Oil = 6 billion Joules=1000kg corn = 125kg beef
Doomsday Prophets or Savants ?
In~1800(population ~1 billion)Thomas Malthus
(economist) wrote "The power of population is
infinitely greater than the power in the earth
to produce subsistence for man" and
"… the passion between the sexes is
necessary and will remain".
In 1973(population ~3.5 billion) Paul Ehrlich
(environmental activist) warned of "… famines
of unbelievable proportions" and feeding 6
billion "... is totally impossible in practice"
March 2008 Analysis
• CBC feature
• Of 6 billion people in the world, 1
billion are obese and 1 billion are
starving
• Redistribution is needed!!
World Food Requirements
WHO estimate = ~2200 Cal/person/day
6 x109 x 2 x 103 = 12 x 1012 Cal/day
Food production: 1965: ~2360 Cal/person/day
1995: ~2740 Cal/person/day
Supply estimated to exceed demand until 2010 AD
Why are 1billion people in the world malnourished >
>>>>Distribution = Politics
www.nationalgeographic.com/
features/2000/population/planet
Wow! Why Worry?
1 North American farmer
can produce food for 100
people.
Food costs(% of income):
W. Europe = >30%
Elsewhere = ?!?!
NA = ~15%(Canada = $6200/family/yr, ie.~11%)
Crop yields(bushels/acre):
Corn(US) - 25(1800)>110(1980)>130(1990)
Wheat(England) - 10(1600)>75(1980)
Rice(Japan/Korea/Taiwan) - 4X(1950>1990)
Food comes from the Land
< 4 billion acres* worldwide used for production of
food( > 0.8 acre/person). * Dropping ~2%/yr
By 2000 ~5 million acres(India + China) had been
degraded so impossible to reclaim, eg. erosion,
overgrazing, deforestation, urban 'development'
(subSahara Africa, Amazon rain forest, even
southwestern Ontario).
Just use more fertilizer; $40/acre would increase
yield 50%(= 2 billion acres).
Cost = $160 billion + pollution.
Distribution of Water in/on the Earth’s Crust
Location
Oceans
Saltwater lakes
Fresh water (easy)
Ground(<0.5 mi)
Lakes
Rivers
Fresh water(hard)
Antarctic ice
Ground(>0.5 mi)
Arctic ice + glaciers
Removal/yr=1000mi3
Volume(mi.3)
%
317,000,000
25,000
97.5
0.3
1,000,000
30,000
300
2.5
6,300,000
1,000,000
680,000
325,000,000 (2 x1018 tons)
Water…LKFs
(little known facts)
Annual withdrawal
(world-wide):
1900 – 600 km3
2000 – 3800 km3
World-wide use of annual replaceable fresh water:
in 2000 – 54%
by 2025 – 70%(90% in underdeveloped countries)
~70% used in agriculture(irrigation – often inefficient)
In Canada..the
Living is Easy!
See:
•worldwater.org
•unesco/water/water_links
•nationalgeographic.com/ngm/0209
Water, Water,
Everywhere and…..
Human body(av)
'excretes' ~2.2L/day
needs 'to drink' ~1.5L/ day
(also food, metabolism).
10% of world population has
adequate potable water.
Unclean water/sanitation kills ~3 million people/yr
(40,000 children/day).
In NA we flush down-the-drain 50,000L/person/yr
Water properties
•
•
•
•
Water acts to moderate Earth’s Temperature
Heat req’d to melt snow and evaporate liq.
High heat capacity: 1cal/gram/oC
Unique in that solid is less dense than liquid
at 4oC: (ice floats!)
Water Cycle
• Moderates the planet
Water in the USA...(trivia?)
Daily use(L)/person
Direct(potable!): drinking/cooking -7; bathing - 35;
dishwashing -14; flushing toilets - 80; laundry –
35; swimming pools/lawns - 85; other - 90
Indirect: industrial - 3800;
irrigation(agriculture/recreation) 2150; municipal(non industrial) - 550
Total = ~6900 (direct - 380; indirect - 6500)
Annual withdrawal = 2X net natural resupply , eg.
the Ogallala reservoir under 8 midwest states has
dropped from 58  8 ft 'thick' since 1930.
Water Trivia
It takes this much water to
produce:
800L - 1kg vegetables
13000L - 1 steak
80L - 1L gasoline
30,000L - 1 ton paper
100,000L - 1 ton steel
2,400,000L - 1 ton 'rubber')
(1 auto = ~300kg of steel)
Most is recycled or 'dumped'(pollution!)
Water –
World Supplies
UN minimum requirement
per person for
drinking/washing/cooking =
50L/day or ~1000m3/yr
A water-stressed country has less than 2000m3/yr/
person of renewable fresh water:
in 2000: 508 million in 31 countries,
by 2025: 3 billion in 48 countries,eg.
India,China(?)
In Canada
it’s Everywhere!
OOPS!
water-level in Great Lakes
drops ~1.2m in last 15 yrs
How Nature corrects itself
• Record snowfalls of 2008 Winter are
expected to produce a 1 foot rise in the
average water level in the Great lakes
• In a year, 25% of the problem from the last
15 years is corrected
• 1” of rain ~ 1 foot of snow
It has to melt!
• Some lost by sublimation
Not so fast………..
• Only net water gain to Great Lakes if source
of snow is not “the lake effect”
• El Nina in Pacific is good : cools NA and
moisture evaporates from Ocean- net gain
in water levels for NA
Water in Canada
Great lakes holds 20% of
the world’s ‘fresh’ water !
But …75% of population,
80% of municipal consumption
90% of industry is American
60% of water runs north into Arctic and ‘unavailable’
Livestock operations in Ontario/Quebec alone
produce manure = sewage from 100 million humans
Water related illnesses ~10,000/yr; deaths ~ 10/yr
Cost to health care system ~ $300 million/yr
Great lakes: chemical “hot spot”
• 1969 River fire in Cleveland
1972: GL Water Quality accord
• PM Trudeau and Pres. Nixon, alarmed by
1969 fire on Cuyahoga River, sign on
1978 Upgrade
• US /Canada agree to “restore and maintain
the chemical, physical and biological
integrity of the waters of the Great Lakes
Ecosystem”
• Commit to rid GL’s of “persistent toxic
substances”-ie those that linger and
potentially poison food sources
Biennial Reports
• Started in 1981-still going
• 1987: emphasis placed on importance of
human and aquatic ecosystem health
• 43 “areas of concern”
2008 Centre for Disease Control
• Report commissioned by the IJC (oversees
issues of GL management)
• 25 “areas of concern”
• Outbreaks of Minimata disease: includes
Cerebral Palsy due to Hg poisoning in
Thunder Bay, Collingwood, Sarnia,
Cornwall
Source of Mercury
• Chlor-Alkali Plants: use Hg in making Cl2
and NaOH. Started in 1894
• 4 cities had large plants (1949-95). 742 tons
released
• Electrolysis of salt water: (Hg) used as an
electrode
• 2Cl- oxidized (LEO) to Cl2. OH- from
reduction (GER) of water . H2 also formed.
Oxidation and reduction
• 2H2O------------------>>H2 + 2OH• 2Cl- ------------------------>> Cl2 (g)
•
•
•
•
Chloride ion loses electrons, LEO
H+ ion in water gains electrons GER
Chlorine and OH- produced
Na+ is spectator ion (no change)
Chlor Alkali plants
• New tech is available, but not Ohio, Wisc.
Gov’ts reluctant to admit problems
•
•
•
•
Health Canada knew in 1990’s
No public report-leaked in 2000
Gov’ts fear lawsuits and expensive cleanups
“there is a reluctance in both US and
Canada to admit that there are ANY effects
of pollutants on fish, wildlife and human
health”
Vital Processes in Food
production
(i) Photosynthesis for carbohydrate
production
(ii) Nitrogen fixation by plants leads to
protein synthesis
(iii)Plants also biosynthesize fatty acids:
Canola etc.
We, and the Earth, need our Nitrogen 'Fix'
" The control of all life forms depends on fixed
nitrogen to form protein."
Inert nitrogen(N2) must be converted to chemically
active species, eg. nitrates, ammonia, that can be
used by plants and animals to make amino acids/
protein.
N2 = :N N: = Inert gas
O2
NO32nitrate
N2
H2
NH3 (NH4+)
ammonia(-ium)
Nitrogen Fixation - au Naturel
• High energy of lightning + O2  NO  NO2 + H2O
 nitric acid (HNO3) = 'acid rain'
• Clover/alfalfa/soy beans(legumes) have N2 fixing
bacteria in their roots(nodules). Can add 100lbs/
acre in one year.
About equal amounts(1 billion tons/yr each)
• Once fixed, the activated nitrogen can be recycled
through dead/decaying organic matter.
Humans cannot 'fix nitrogen' and must consume
plants/animals to obtain their requirements.
Nitrogen Fixation - in the Lab
The(Fritz)Haber Process(~1910) - Nobel prize 1918
N2(g) + 3H2(g)
2NH3(g)
First developed for explosives!
By 1880s it was recognized that 'active nitrogen
compounds' would be necessary as fertilizers to
'feed the world'. By 2000 ammonia is one of the 'top
ten' chemicals produced in the world.
#6 in USA, at:
20 million tons/yr
BUT using energy = 300 million barrels of oil
Plant Nutrients
Non-mineral:
C(CO2), H/O(H2O)
*Primary: (N)nitrogen, (P)phosphorus, (K)potassium
Secondary: (Ca)calcium, (Mg)magnesium, (S)sulfur
Trace: boron, chloride, copper, iron, manganese,
molybdenum, sodium, zinc, (nickel, vanadium)
* can be obtained 'naturally' from manure, guano
(bird 'droppings'), bone/fish meal
Fertilizers (N, P, K)
- the Big Three
Nitrogen/Phosphorus/
Potassium
% of N, P2O5, K2O =
the 3 #s on the box/bag
eg. 5 - 10 - 5
(manure = 0.5 - 0.3 - 0.5)
As soluble salts, easily assimilated by the plants
but easily leached away and not recoverable
Can be quick/slow release
Can be complete(all three); straight(one of the three)
Nitrogen (Ammonia / Nitrates)
Now almost exclusively by the 'Haber process'
Sometimes in the form of liquid/'anhydrous'
ammonia (gas, bp.-33oC) but easier/less dangerous
as solids/salts. Combined with:
Carbon dioxide: (urea - H2NCONH2)
Acids: sulfuric (ammonium sulfate - (NH4)2SO4)
nitric (ammonium nitrate - NH4NO3)
phosphoric (ammonium phosphate - (NH4)2HPO4
Natural sources exhausted / too expensive after
~1950, eg.'Chilean saltpeter'(NaNO3) and 'guano'
(Chile/Peru)
Nitrates too much Bang,
too many $$ ?
*Ammonium nitrate
(NH4NO3)
Are we hooked?
For how many more decades can we afford the
high costs of production (non-renewable energy)
and nitrate pollution(non-accountable).
*Commonly used as an explosive, eg. World War I,
Oklahoma City, 1995 and elsewhere
Phosphorus (Phosphates)
Recognized in early 1800s, first in Europe, that
'phosphate' was a critical for plants. After skeletons
from battlefields were 'used up', larger supplies
were required and in more soluble form, so;
Ca3(PO4)2 + 2H2SO4  Ca(H2PO4)2 + 2CaSO4
superphosphate
also from: phosphate rock + phosphoric acid
Largest deposits in Florida and Morocco (2/3 world
supply!). Estimated to last for 30 - 40 yrs; then
under Atlantic Ocean off Carolinas.
Phosphate Pollution
• Food for blue-green algae (cyanobacteria) :
summer 2007
• Fertilizers, detergents enter natural waters
Potassium
Used as cation(K+),
thus any soluble salt
will do.
Most common form is potassium chloride (KCl).
World class deposits developed in:
> Germany, before World War I
> USA, eg. Carlsbad, NM
> Canada(Saskatchewan, 200m thick & 1.5 km
below ground); buy shares(?) in Potash Corp
The Future…….
• What are your views on
• (i) the best Energy sources (and why)
• (ii) solution to pollution
Global Environment
• Some necessary steps
• Population control: reduce/stabilize overall
E and food demands
• Nuclear power: Clean-low level radioactive
waste buried deep in the ground (its origin);
no C emissions. Oil has max 100 years left.
• Make clean technology financially
attractive (gov’t initiatives/grants)
The problem with David Suzuki
• Refuses to acknowledge the reality of
nuclear power as the future
• France (highest ~60% nuclear) has cleanest
air in Europe
• Wind/solar/wave/biomass etc.OK for off
grid applications, but not practical for
constant large urban needs
Some positive signs
• Ont Gov’t plans new nuclear power facility
• Alberta considers nuclear power option
despite “tar sands” resources
• 1 barrel of oil used to produce 2 barrels in
Tar sand project (CBC feature March 2008)
• Huge CO2 emitter. Nuclear is the solution
But……..some big negatives
• Alberta tar sands: world’s largest oil
resource outside Saudi Arabia
• BUT..requires a lot of Energy to extract it
(~ 1 barrel of oil to produce 2 )
• AND-massive environmental destruction
Environmental damage due to
Tar Sands projects
• Deforestation
• Tailing ponds
Tailing pond contents
• Most dangerous contaminant is naphthenic
acid (PNAH with carboxylic acid bonded to
it)
• Process of extraction involves using vast
quantities of hot water, naptha and paraffin
in order to separate the sparingly soluble
butumen from the tar sands
The leftovers!
• Each cubic meter of bitumen extracted
produces 3-5 X the volume of aqueous
“tailings” that must be stored
• Area the size of Lake Ontario needed!visible with naked eye from outer space
• Also alkyl substituted PAH’s (carcinogenic)
in these ponds
Effects on neighboring
communities
• Fort Chipewan (1st nations ; downstream
form tarsands projects)
• Greater incidence of cancer, lupus and MS
since tarsands development started