Water contamination - how can we stop it?

By Colin Windell

 

Nitrate contamination is the most common chemical compound being found in groundwater and the source of this is from farming activity.

In many countries the biggest source of water pollution today is agriculture — not cities or industry — while worldwide, according to the ‘More People, More Food, Worse Water? A Global Review of Water Pollution from Agriculture’, report launched by the Food and Agriculture Organisation (FAO) and the International Water Management Institute at a conference in Tajikistan.

The report, said modern agriculture is responsible for the discharge of large quantities of agrochemicals, organic matter, sediments and saline trading into water bodies.

It said this pollution affects billions of people and generates annual costs exceeding billions of dollars.

“Agriculture is the single largest producer of wastewater, by volume, and livestock generates far more excreta than do humans. As land use has intensified, countries have greatly increased the use of synthetic pesticides, fertilizers and other inputs,” wrote Mr Eduardo Mansur, Director of FAO’s Land and Water Division, and Ms Claudia Sadoff, IWMI Director-General, in their introduction to the report.

“While these inputs have helped boost food production, they have also given rise to environmental threats, as well as to potential human health concerns.”

The report said agro-pollutants of greatest concern for human health were pathogens from livestock, pesticides, nitrates in groundwater, trace metallic elements and emerging pollutants, including antibiotics and antibiotic-resistant genes excreted by livestock.

The report said since 1960 the use of mineral fertilizer had grown 10 times, while since 1970 global sales of pesticides climbed from around one billion dollars to $35-billion a year.

It went on to state the intensification of livestock production — world livestock numbers have more than tripled since 1970 — had seen a new class of pollutants emerge: antibiotics, vaccines and hormonal growth promoters that travel from farms through water into ecosystems and drinking water.

At the same time, water pollution by organic matter from livestock farming was now significantly more widespread than organic pollution from urban areas.

Another booming sector, aquaculture (which had expanded 20-fold since 1980) was now releasing ever greater amounts of fish excreta, uneaten feed, antibiotics, fungicides and anti-fouling agents into surface waters.

On what could be done, according to ‘More People, More Food, Worse Water’, water pollution from agriculture was a complex challenge and effectively managing it requires a range of responses.

According to the report, the most effective way to mitigate pressure on aquatic ecosystems and rural ecologies was to limit the export of pollutants at the source or to intercept them before they reach vulnerable ecosystems and to to develop policies and incentives that encourage people to adopt more sustainable diets and limit increases in demand for food with a large environmental footprint — for example taxes and subsidies.