Rivers nitrate concentrations increased

Major run-off events are a feature of most intertidal areas associated with estuaries. The high flows may limit nutrient processing due to decreased water residence times however, if concentration increases with flow, nutrient processing may increase depending only on the biokinetics of the process. The concentration of nitrate in river water tends to increase with... 

Between 1975 and 1985 nitrate concentrations in the Meuse and the Ijssel rose by 15-25%, and similar, or much higher, increases were recorded in other European rivers nitrate... 

In contrast, during the low flow season (June-October) important nutrient loads from both point and non-point sources are relevant. Summer irrigation drives nitrate inputs to stream waters [38], The lower dilution capacity of the river causes higher concentrations of nitrate and DOC, as well as an increase in phosphate content with... 

An increase of C02 concentration in the atmosphere does not determine substantial fertilization of marine bioproductivity—but does lead to pH decrease. As temperature grows, C02 assimilation by the ocean decreases, but C02 emissions due to upwellings are reduced and the transport of excess carbon to deep layers of the ocean diminishes. The anthropogenically induced input of nutrients to the oceans through river run-off and deposition of atmospheric aerosols (especially nitrate and iron as elements of atmospheric aerosols) can affect bioproductivity. 

During the second part of the 20th century, river flux of organic matter, nutrients and pollutants markedly increased. For example, increase in concentration of ammonia nitrogen is 2.5 times, of nitrites and nitrates 4 and 5 times respectively, of phosphate 2 times. Since the beginning of 1970s, the concentration of heavy metals and oil in river water has also increased [9]. Over the period 1996-2000, the input of the contaminants to the Black Sea with the Danube waters comprises oil 53 x 1012 t, Cu 1.2 x 1012 t, and Zn 3.3 x 1012t [9],... 

The depletion of silicate in surface waters during the 1970s and 1980s has also been found to have an important impact on shifts of phytoplankton species composition from siliceous (mainly diatoms) to non-siliceous (coc-colithophorids and flagellates). Recent changes in nutrient concentrations of the river inputs have resulted in changes in the coastal waters concentrations of nitrate decreased considerably and concentrations of silicate increased [83]. 

River Pollution. The sampling plan has to allow for the variations in flow rate and concentrations of nutrients in different parts of the river. So it is not adequate simply to sample the middle of the river. The study might be related to the effects of sewage works (anticipating increased loads of ammonia and phosphate or the suspected leaching of nitrate from agricultural land). 

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