SCIENCE MATTERS by David Suzuki with Faisal Moola
If youve been following news about the upcoming Beijing Olympic
Games, you may have seen photos of thousands of workers trying to
clean huge swaths of algae from the waters and beaches in co-host
city Qingdao. The algae have proliferated over a third of the waters
where sailing events will be held.
This is not an unusual occurrence, but it is a symptom of an underlying
problem with potential repercussions far more serious than hampering
Olympic events or adding to the negative publicity surrounding Chinas
games. The blooms along with a host of other problems
are caused by excessive amounts of nitrogen from sources such as
road and industrial run-off, untreated sewage and, most of all,
fossil-fuel combustion and agricultural fertilizers.
Because it is a major component of proteins and the atmosphere,
nitrogen is a vital element in the biosphere. In the soil, nitrogen
stimulates growth in plants. Normally, bacteria in soil can take
atmospheric nitrogen and combine it with hydrogen to create a molecule
that plants can use. We can fix nitrogen from the air
into fertilizer in a process that takes a lot of heat from fossil
Applied on farmers fields, this artificial fertilizer induces
plant growth, but scientists believe that this has resulted in nitrogen
entering the Earths soils at more than twice its natural rate.
This ripples out from the land to affect freshwater and marine ecosystems.
Besides giving Chinese Olympic organizers headaches, algal outbreaks
have also contaminated drinking water supplies used by millions
Excess nitrogen can also disrupt or change plant growth patterns
(including contributing to the spread of invasive species), poison
freshwater environments, deprive ocean ecosystems of the oxygen
needed to support aquatic life and even contribute to global warming.
In one particularly troubling example of the impact of all this
nitrogen, scientists predict that a massive dead zone
in the Gulf of Mexico will grow to more than 26,000 square kilometres
this summer, which is more than 50 percent greater than the yearly
average since 1990. Thats an area about half the size of Nova
Scotia! Dead zones are caused by nitrogen and phosphorous washing
into the ocean and stimulating growth of excessive amounts of algae
and other plants, which then starve the area of oxygen.
Ironically, the increase is fuelled in part by the rush to find
alternatives to fossil fuels that contribute to global warming.
Farmers along the Mississippi River have been planting more corn
and using more fertilizer to meet the demand for corn-based biofuels.
Corns shallow roots dont hold and absorb all of the
fertilizers so much of it washes into streams that flow into the
Mississippi, which drains into the Gulf of Mexico.
In a process known as eutrophication, the nitrates and phosphorous
from the fertilizers, along with carbon from the air, stimulate
growth of algae and other nuisance plants in the water. When the
plants grow, die and decay, they block the sun and use up oxygen,
thus decreasing the supply of dissolved oxygen in the water. This
process occurs in lakes and oceans. The decayed plants also fall
to the bottom and create layers of slime on the lake or ocean floor.
Scientists say these dead zones are growing in size and number,
with as many as 200 now believed to have formed in the Earths
Nitrogen also contributes to global warming, through fossil-fuel
emissions and other human activities such as agriculture, as well
as by eutrophication. Nitrogen itself is harmless and makes up 80
percent of our atmosphere, but nitrous oxide, a by-product of nitrogen
from fossil fuels and agricultural practices, is 300 times more
potent as a greenhouse gas than carbon dioxide, although carbon
dioxide is far more prevalent in the atmosphere.
Because we know where much of the excess nitrogen in the environment
comes from, we know how to reduce the levels. First, we must cut
back on fossil fuels. But we can also reduce our use of chemical
fertilizers in agriculture, on golf courses and even in our own
back yards. We may not be able to fix the problem in time for the
2008 Olympics, but we need to get on it now or well have far
bigger problems to contend with than where to hold Olympic sailing
Take the Nature Challenge and learn more at www.davidsuzuki.org