RE-OLIGOTROPHYZATION in deep rivers and lakes
The case of the river Ebro
The eutrophication - the excessive enrichment of a body of water with nutrients such as nitrogen (N) and phosphorus (P) - is the most widespread problem on Earth for water quality. However, in rivers, reservoirs, lakes and estuaries in developed countries and emerging economies, the current reduction in nutrient inputs - called re-oligotrophication - is much greater for P than for N.
Although the rapid emergence of this phenomenon has made it difficult to monitor ecological effects in detail, some studies have documented an accelerated shift from green waters to clear waters and hence from phytoplankton to macrophytes as dominant primary producers in response to reoligotrophication. However, the improvement in water quality due to the decrease in P does not necessarily imply a return to pristine ecological conditions, as high N:P ratios cause some undesirable or uncontrolled changes in the ecosystem.
Continue reading : Changing nutrients, changing rivers (Science 16Agosto2019, DOI: 10.1126/science.aay2723)
Nitrogen in the environment Excess nitrogen causes problems in developed nations, but nitrogen-poor soils threaten food security elsewhere (Science 14Febrero2019, DOI: 10.1126/science.aav8215)