Two major pollutants: nitrogen and salt

The report contains a study of two major pollutants over the period 2000-2010: nitrogen and salt, through lack of data on emerging pollutants such as plastics.

Indeed, nitrogen is one of the main causes of poor water quality, especially in developed countries. Since 1960, the quantity of nitrated fertilisers used around the world has risen by more than 600%. More than half the nitrogen used as agricultural fertiliser is released into the atmosphere, where it accentuates the greenhouse effect, and into water, where it transforms into nitrates. The latter disturb aquatic habitats and trigger the proliferation of algae that consume oxygen when decomposing. The ecosystem, thus exhausted, then gradually disappears. Nitrogen also presents a problem for human health and thus has an economic cost. When humans consume water with high nitrate content, their blood can no longer correctly carry oxygen, leading to methemoglobinemia – “blue blood” – a condition caused by nitrate/nitrate poisoning to which infants are particularly vulnerable.

The salinity of water and soils is another danger. Salt contamination is constantly increasing due to severe droughts, the increase in ocean levels and greater withdrawals from coastal underground aquifers. In Bangladesh, at least a third of the population drinks water with excess salt content. The World Bank has reported that in the country’s coastal regions, about 3% of infant deaths can be attributed to the consumption of salt water.

Furthermore, this phenomenon reduces farm yields. The quantity of food lost to humans each year due to salt water is enough to feed 170 million people.

An impact on economic growth

 

The study included a third indicator, biochemical oxygen demand (BOD) in watercourses – the indirect measurement of overall water quality – and it was correlated with the economic growth of the region concerned. The result is beyond dispute: when the level of oxygen in water is very low, the growth of GDP in regions located downstream falls by an average of 30%, due to the impacts of this pollution on health, agriculture and ecosystems.

Measures can be taken to improve water quality, as recommended by the report: environmental policies and standards; precise assessments of pollutant loads; the development of water treatment infrastructures with incentives in favour of private investment; the communication of reliable and accurate information to households, etc.

Remedying this situation nonetheless remains difficult for countries lacking the financial capacity to set up these measures while at the same time undergoing demographic growth. Mention can be made of the example of Kenya. The Kenyan government recently stated that more than 4,400 pollutants had been detected in the Nairobi river and announced the launch of a plan to radically combat this pollution, by acting to close factories and take financial sanctions against industrial groups.

It should be recalled that worldwide, more than 80% of wastewater is currently discharged without treatment.