Scientists warn of the dangers of salt pollution of freshwaters if preventive measures are not taken

The study, prepared by an international team of scientists coordinated by the researcher Miguel Cañedo-Argüelles, of the BETA research group of the University of Vic -- Central University of Catalonia (UVic-UCC) and the FEM research group of the University of Barcelona (UB), reveals that human activities such as agriculture and resource extraction (coal, minerals, gas, etc.) are increasing water salinity and this has adverse effects on human health and ecosystem functioning. Narcís Prat, professor at the Ecology Department of the University of Barcelona and leader of the UB Freshwater Ecology and Management (FEM) research group, also took part in this work.

In addition, increased water salinity could have very high economic costs due to loss of ecosystem services and direct costs related to water treatment for human consumption. The study also warns that in most cases preventive actions focus solely on human uses of water, ignoring the protection of aquatic biodiversity. Some countries, like Australia and the United States, have made progress in regulating permitted salinity levels on the basis of ecological criteria. Even so, the degree of protection is insufficient. As stated by the researcher Miguel Cañedo-Argüelles, "In most cases these are only recommendations (not legally binding) based on the total quantity of salt (i.e. salinity), without taking into account the concentration of different ions (e.g. chloride, magnesium, sulfate, sodium, etc.)." It is known that different ions have different toxicity, and therefore the authors call for specific legislation to regulate concentration limits of each ion in our rivers and lakes.

In the article, whose authors include the director of CT Beta Tecnio (UVic-UCC), Sergio Ponsà, UVic-UCC ICREA researcher Sandra Brucet Balmaña and the director of the FEM research group (UB), Narcís Prat, the scientists call for global solutions and preventive policies based on the scientific consensus, taking into account social, economic and environmental issues in order to protect aquatic ecosystems from increasing salinity and to ensure access of future generations to the goods and services these ecosystems provide. They also predict that climate change will aggravate this situation because water evaporation will increase, diminishing the capacity of rivers and lakes to dilute salts, and sea level will rise causing salt water to invade fresh water in coastal areas.

The researchers propose incentives for good practices and the use of technology that will reduce salt concentrations in freshwaters. For example, they argue for new agricultural techniques with cultivation of crops that permit a rational use of water. They also recommend permits and controls for enterprises that discharge salt-rich effluents into rivers and lakes in order to control the concentration and timing depending on the dilution capacity of receiving waters, as it is being done in Australia. They admit that ecological disasters caused by increasing salinity, though few in number, have brought about large-scale loss of biodiversity and suffering for human inhabitants affected, as is the case of the fisheries collapse in the Aral Sea and the limited access to safe drinking water in the Ganges delta in Bangladesh.

They also consider that we are still in time to prevent further disasters of this kind if appropriate prevention and management practices are put in place. Nonetheless, increasingly saline aquifers and arable land already make it impossible to cultivate certain crops (as in the Ebro valley), rendering it harder to produce food and provide drinking water, all of which, besides ruining many families, could lead to increased international migration. The countries of southern Europe will suffer most from this situation and experience greatest difficulties in economic activities, especially agriculture.