Agriculture’s impact on water pollution

It’s thousands of square miles wide, virtually devoid of oxygen and it has been
blamed for an increase in shark attacks: the Gulf of Mexico “Dead Zone” is
getting bigger and forcing marine life — including sharks – into shore.
The zone has been caused by a flood of nutrients, such as agricultural fertilizers,
which boost algae production in the sea. These growths consume huge amounts
of oxygen creating a “marine desert” almost devoid of life.




The “Dead Zone” varies in size each year, but in 1999 it was 7,728 square
miles — that’s nearly the size of Delaware and Connecticut combined.

The huge size of the “Dead Zone’ is due to the increase in nutrient pollution
flowing down rivers, including the Mississippi, which is estimated to have risen
threefold in the last fifty years as chemicals become more and more common
on farms.

Environmentalists fear that the drive to radically increase the amount of
corn-based biofuels produced in the U.S. from 15 billion gallons to 36 billion by
2022 could increase pollution in the Mississippi by 19 per cent.

But the problem is by no means limited to U.S. waters.

Similar “Dead Zones” are being discovered across the world and a major
United Nations report in 2003 found that the number had doubled each decade
since the 1960’s.

The UN report also warned that the number will continue to increase as
intensive agriculture spreads around the world and that they are already
having a significant impact on commercial fish stocks. All of this can come
as quite a surprise.

Growing water demands, more pollutants

Think about pollution and you tend to imagine tall smoking chimneys or pipes
pouring industrial effluent into our rivers and lakes. But the use of chemicals
in agriculture is increasingly becoming a concern for environmentalists across
the world.

Agriculture, including livestock and poultry farming, can be a source of a wide
range of pollutants that find their way into our water supplies through run-off
and leaching. This happens when rainfall exceeds the capacity of the ground and it
flows into watercourses and groundwater supplies taking dissolved pollutants with it.

These can include sediment from eroded land, as well as phosphorus and nitrogen compounds from chemical fertilizers and animal waste, which can also harbor
disease pathogens.

These pollutants can have a serious effect on water sources by depleting
oxygen levels, stunting the growth of plants and even suffocating fish — as in
the Gulf of Mexico “Dead Zone.”

The concentration of pollutants can be particularly high in drought years, when
heavy water demand can reduce the flow rate in rivers and cut their ability to
dilute chemicals.

The effects of this can be acute in the developing world, where the pressure
to feed a growing population combined with a low level of regulation can cause
serious problems.

A huge increase in the amount of synthetic chemicals being used in the Philippines
over recent years has caused substantial environmental damage to the country’s
water supplies, according to a 2008 report by Greenpeace.

Between 1961 and 2005 fertilizer use in the Philippines increased by 1000
percent.

“This model of agricultural growth is fatally flawed because of declining crop yields
and massive environmental impacts,” says Greenpeace campaigner Daniel Ocampo.

“Aside from causing land degradation and losses in soil fertility, agrochemicals
cause water pollution that directly and indirectly affects human health.”

According to Greenpeace, analysis of groundwater in the Benguet and Bulacan
provinces in the Philippines, found that 30 percent of tested wells had nitrates
levels above the World Health Organization (WHO) drinking water safety limit.

The Philippine National Economic and Development Authority (NEDA) says that
37 per cent of water pollution in the country originates from agricultural practices.

As well as causing an increase in the algal blooms that can cause “Dead Zones,” agricultural nitrates have been identified as a factor in the growth of toxic
“red tide” algae and high levels in drinking water can also pose a health risk
to humans, especially children. …More….