Figure 1
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Data sources:
Data was provided from National Environmental Monitoring Department of the Ministry of Ecology and Natural Resources under the ENI SEIS II East project activities
Note: The data series are calculated as the average of annual mean of BOD5 (mg O2/l) (top) and ammonium concentration (mg NH4-N/l) (bottom) for river monitoring sites in the whole of Azerbaijan (left) and in different regions (right) for the period 2001-2017. The number of monitoring sites is given in parenthesis.
Biochemical oxygen demand (BOD) and ammonium are key indicators of organic pollution in water. BOD shows how much dissolved oxygen is needed for the decomposition of organic matter present in water. Concentrations of these parameters normally increase as a result of organic pollution caused by discharges from waste-water treatment plants, industrial effluents and agricultural runoff. Severe organic pollution may lead to rapid de-oxygenation of river water, high concentration of ammonia and disappearance of fish and aquatic invertebrates. Some of the year-to-year variation can be explained by variation in precipitation and runoff.
Over the whole time period there has been a slight increase in ammonium concentration and a slight decrease in BOD (by 32%% and 25%, respectively, if comparing the last three years to the first three years). However, BOD has increased since the minimum level in 2012. For both determinands there was a period with higher levels than the most recent level. This period occurred somewhat later for ammonium than for BOD.
The regional time series patterns are fairly similar to the national patterns. For BOD the levels differed clearly between the regions up until 2010, with the highest levels in Shirvan and Gazakh-Ganja and the lowest in Lankaran-Astara (only represented by two sites). In recent years the results have been more similar. For ammonium concentrations the regions differed most clearly during the peak period (2009-2014), with the highest concentrations found in Gazakh-Ganja.
Transboundary transport, industrial and agricultural production in Azerbaijan, old sewer systems in some areas, and lack of solid waste management in some rural areas have led to an increase in organic pollution up to 2010. The Shamkir and Mingachevir reservoirs along the Kura river were affected by the discharge of waste-water from many settlements in the Kura basin. Over the last 7-8 years, the installation of new modern waste-water treatment plants in the country has reduced organic pollution.