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Danube: Nature of the Problem

Page history last edited by Liz Dyer 11 years, 9 months ago


II. Nature of the Problem


 The central problem facing the Danube River Basin is the eutrophication of the river and of the Black Sea via point and diffuse sources. The problem of eutrophication begins from excessive nutrients, being nitrogen and phosphorus, entering a body of water from various sources which leads to degraded ecological health. This increase in nutrient density allows for an increase in the amount of bio-life in the region, albeit is typically only a few different species that can survive in these new conditions thus decreasing biodiversity. The species that typically thrive in these new conditions include algae and phytoplankton and form giant algal blooms. The scale and frequency of these massive blooms can be seen in Figure 2 as they are scattered across the basin region.



(Due to bugs in pbworks this image will not show up unless the pdf version is downloaded.)


              Figure 2. Shows the nitrogen pollution from point and diffuse sources http://www.icpdr.org/icpdr-pages/drbmp_maps_2009.htm 




As time passes these massive populations eventually die and decompose. The decomposition process of this massive amount of biomass consumes large quantities of oxygen and results in a great decrease of dissolved oxygen in the river. These low dissolved oxygen levels lead to several problems in the biosphere including hypoxia (i.e. not enough oxygen reaching the tissues) in many species (ICPDR, 2006).


The issue of eutrophication is not a new one to the Danube River. As stated by the ICPDR “Excessive amounts of nutrients have for many decades been entering the Danube River Basin – particularly from agricultural sources. The excess nutrients may cause eutrophication and disturb the ecological balance of the river and the Black Sea.” These nutrients typically enter the river through run off, coming from fertilizers used in agriculture along municipal waste containing phosphoric laundry detergents. The point source locations of these pollutants can be seen in Figure 3 below.



Danube: Image- P Levels.tiff


              Figure 3. Shows the phosphorus pollution from point and diffuse sources http://www.icpdr.org/icpdr-pages/drbmp_maps_2009.htm  



The orange markers in this map show the untreated municipal waste that enters the Danube River, which is located in the middle and lower sections of the basin in which countries are less wealthy and may not be able to afford waste treatment plants. These sources of untreated waste are a key point source of phosphorus entering the river. It is important to note that this diagram does not show the non-point sources of nutrients entering the river. These sources are much more difficult to locate but are considered to be from agricultural runoff located along the basin.


This problem of eutrophication has many negative effects on the surrounding environment and the people living in the basin. Due to hypoxia there is a decrease in aquatic life, negatively affecting the ecosystem and also resulting in less fish for fishermen to capture and sell which affects their livelihood (Global Environment Facility, 2010).  The fishing industry is not the only portion of the economy affected by this problem. Due to these excess nutrients additional treatment of drinking water is required, putting an economic burden on the people living along the river. If left untreated the excess nitrate in drinking water can reduced the body’s ability to deliver oxygen to the cells resulting in several negative effects and also increased health care costs (USEPA, 2011).


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