Figure 1
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Data sources:
Data was provided by the Ministry of Environment of the Republic of Armenia under the ENI SEIS II East project activities
(C10, C11) Water quality indicator, by observation points and years provided by ArmStatBank
Note: The data series are calculated as the average of annual mean concentrations for river and lake monitoring sites in Armenia for the period 2008-2017. The number of river sites is 45 (21 sites above settlements and 24 below), representing 22 rivers. The number of lake sites (Lake Sevan) is 4. The right hand river plots show the average time series without the site 55.
Large inputs of nutrients to freshwater from urban and agricultural point and non-point sources can lead to ecological changes, eutrophication of water and have negative impacts on the use of water for human consumption and other purposes. The main source of nutrients in Armenia is agriculture, wastewater and storm water. There are only six treatment plants in Armenia, with mechanical treatment only. Nitrate pollution is mainly associated with agriculture.
The average river nitrate concentration below settlements increased by 29% from 2008 to 2017. This is related to increased emissions from wastewater and agriculture. Above settlements there was a slight decrease (5%), leading to a less marked increase for the set of river sites as a whole (18%). Over the same period the average river phosphate concentration below settlements increased by 244%. However, the concentrations in 2008 were particularly low. Looking at the time period 2009-2017 the increase was 34% below settlements. Although the average concentration level was lower, the relative increase was about the same above settlements (31%). Overall, this gave an increase of 33% from 2009 to 2017 (265% compared to 2008).
River Hrazdan is one of the longest and most polluted rivers in Armenia, and especially the site 55, which is the nearest site after Yerevan City has very high phosphate concentrations. Removing this site from the average reduces the phosphate concentration below settlements by 14-27%, depending on the year, and consequently the average concentration across all sites is also reduced. No such effect is seen for nitrate, indicating that wastewater is the major contributor at this site.
Average nutrient concentrations in Lake Sevan increased markedly over the period 2008-2012, which was a result of the increasing lake level. Residential buildings, roads and forests were covered with water, which led to hydromorphological changes and caused nutrient pollution of Lake Sevan.
Average total phosphorus concentration in Lake Sevan increased over the period 2013-2017. Diffuse runoff from agricultural land and untreated domestic wastewater continues to be important sources of phosphorus emissions to Lake Sevan. These pollution sources do not have a big impact on the rivers in the region, but they affect Lake Sevan due to direct discharge into the lake. Moreover, phosphorus stored in the sediment can keep lake concentrations high and prevent improvement of the water quality.