A snapshot of the world’s water quality: water pollution increases in Africa, Asia and Latin America
A polluted river near Suide, China. Image: Adam Cohn | Flickr Creative Commons
Water pollution has worsened since the 1990s in many rivers in Africa, Asia and Latin America, according to a new report ‘A Snapshot of the World’s Water Quality: Towards a Global Assessment‘ by the United Nations Environment Programme (UNEP). High levels of pathogens such as cholera and typhoid are present in around a third of all rivers in the three regions, creating a health risk for millions of people who rely on freshwaters for drinking, bathing and cleaning.
Severe organic pollution (primarily from untreated sewage in wastewater and agricultural fertilisers) impacts around 15% of rivers in Africa, Asia and Latin America, which is reported to place stress of the health and status of fish populations (e.g. through harmful algal blooms and reductions in dissolved oxygen in the water), with knock-on effects for food security of communities who rely on fishing. Both organic and pathogen pollution worsened between 1990 and 2010 in more than half of rivers in the three regions.
Moderate-to-high salinity levels were detected in around 10% of rivers surveyed across the three regions. As with the other two types of water stresses, salinity is reported to have increased in around a third of rivers in the study regions between 1990 and 2010, as a result of many rivers receiving flows of salt-laden irrigation wastewater, domestic wastewater from urban areas and mine runoff, and where water level are reduced by climate changes and/or abstraction.
Freshwater organisms often only tolerate a fixed range of levels of dissolved salts in their habitats, and increased salinity can therefore place significant stress on their health (as reported in this 2013 journal paper). Water with high salinity levels is likely to also require treatment before it is safe for humans to drink.
The UNEP undertook their study as a means of assessing progress towards improving global water security, linked to their set of 17 Sustainable Development Goals. The report highlights the central role that freshwater quality plays in water security, but notes that global assessments of water quality are still patchy and incomplete, particularly in the developing world. As such, the new report is a precursor to an intended global assesment of water quality.
The report highlights that global trends in freshwater quality are uneven, and that whilst broad improvements are being made in some – often more developed – regions (e.g. through the Water Framework Directive in Europe, and the Clean Water Act in the USA), water quality is falling in large parts of the world. Such decreases in water quality often have a range of negative impacts on human and non-human lives which are inextricably tied to freshwater ecosystems.
These impacts can be unevenly spread amongst society, too. The report suggests that women and children are particularly at risk from pathogen pollution, as in many developing countries they may be the members of society who have most contact with water through cleaning, washing and cooking.
The key driver of decreasing water quality in Asia, Africa and Latin America is the growth in non- or poorly-treated wastewater discharges into freshwaters. The report advocates improvements to wastewater treatment infrastructure where pollution from urban populations and industry is high. However, this is far from a straightforward process, dependent on appropriate finance and political will, and often more locally-specific in terms of small-scale society-environment interactions and development trends than this broad-scale assessment can cover in a detailed way.
Despite the negative trends, the report ends on a hopeful note: whilst water pollution is getting worse in Asia, Africa and Latin America, the majority of rivers in the three regions are still in ‘good’ condition, with some barely affected by pollution. Moreover, it is suggested that there is significant potential for their ongoing conservation and restoration in response to well-documented ongoing threats.
Such freshwater conservation attempts across the three regions could be strengthened by four actions, according to the UNEP authors: better monitoring of water quality; comprehensive assessments of national and global water quality to allow for locally targeted conservation; the transfer of knowledge on new approaches for water management (e.g. nature-based solutions and new treatment technologies) to developing countries; and the promotion of good governance and effective institutions to support these initiatives.
The report authors emphasise that protecting and improving water quality should be considered an integral part of environmental sustainability, as outlined by the UNEP Sustainable Development Goals. This highlights the interdependence of freshwater ecosystem health and status and human livelihoods, and the potentially wide-ranging effects that changes to water quality can have on all our lives.
The Freshwater Blog 