C11 – Nutrients in freshwaters of the Republic of Moldova
Are concentrations of nutrients in freshwater in Moldova decreasing?
Figure 1 – Changes in concentrations of nutrients in rivers of the Republic of Moldova (1992-2017)
Data sources
- Data were provided by Environment Quality Monitoring Division of the State Hydrometeorological Service of the Ministry of Agriculture, Regional Development and Environment, under the ENI SEIS II East project activities.
- Water quality database of Dniester river basin, State Hydrometeorological Service.
Note: The data series are calculated as the averages of the annual mean concentrations of nitrate (mg NO3-N/l) (top) and total phosphorus (mg P/l) (bottom) for river sites in the two river basins of Moldova (Prut basin and Nistru (Dnister) basin) and in the Black Sea basin in Moldova (direct tributaries of the Black Sea), as well for the whole country for the period 1992-2017. The number of river sites is given in parenthesis. The total number of river sites is 19.
Figure 2 – Changes in concentrations of nutrients in lakes of Moldova (1992-2017)
Data sources
- Data were provided by the Environment Quality Monitoring Division of the State Hydrometeorological Service of the Ministry of Agriculture, Regional Development and Environment, under the ENI SEIS II East project activities.
- Water quality database of Dniester river basin, State Hydrometeorological Service.
Note: The data series are calculated as the averages of annual means of nitrate concentrations (mg NO3-N/l) (top) and total phosphorus (mg P/l) (bottom) for three lakes in Moldova for the period 1992-2017.
The average nitrate concentration in rivers in the period 1992-2017 was 5.11 mg N/l. The highest peak in nitrate was in 1998 (11.70 mg N/l) and the lowest in 2010 (3.08 mg N/l). The overall trend in nitrate concentration in rivers is negative, but there are large difference between sub-periods. Between 1992 and 1998 the annual average concentrations of nitrate in freshwater were increasing, after which the trend changed. Between 1998 and 2005 the trend was significantly negative. In the 12 years from 2005 to 2017 there was no significant trend. Concentrations of nitrate fluctuate around a multiannual average of 4.3 mg N/l.
The highest concentrations of nitrates are found in the rivers in the Nistru basin (the average for the period 1992 -2017 was 7.38 mg N/l). Here, the maximum average annual concentration exceeded 15 mg N/l in 1998. Rivers in the Prut basins have an average annual concentration of 3.05 mg N/l; the highest concentrations were in 1994 (2.59 mg N/l) and 2001 (2.46 mg N/l).
The highest annual averages of total phosphorus concentration in rivers were in 2008, 2012 and 2016, when all values were above 0.34 mg P/l. There is no significant trend in phosphorus concentrations in the freshwaters of Moldova. In the Nistro basin, the phosphorus concentrations are slightly increasing. This may indicate a lack of waste water treatment and an increase in the use of phosphate-based detergents throughout the area.
The highest average nitrate concentration in lakes was in 1998, after which it started to steadily decrease. At present, the average annual nitrate concentration in lakes is lower than 0.5 mg N/l. The lowest concentration has been in Ghidighici lake on the river Bîc in the Chișinău area. All lakes showed negative trends in nitrate concentration following the peak in 1998. The reason for this might be a decrease in agricultural activities. The same negative nitrate trend has been seen in rivers as well.
The average total phosphorus concentration in the three lakes studied (Dubăsari Centrala Hidroelectrică, Costești Centrala Hidroelectrică and Ghidighici lake on the river Bîc (Vatra, Chișinău) was around 0.10 mg P/l between 1994 and 2007, after which the concentration started to increase. Nevertheless, this is due to a very high increase in phosphorus in Ghidighici lake in the Chișinău area. The other two lakes are reservoirs on rivers (used for hydroelectric power) and have rather stable and low phosphorus concentrations (< 0.1 mg P/l). The increasing trend in phosphorus in Ghidighici lake until 2012 might be related to a larger input of untreated urban waste water and greater use of phosphorus-based products in agriculture.
What is the current state of nutrient pollution of rivers in Moldova?
Figure 3 – Nutrients in rivers of Moldova in 2017
Data sources:
- Data were provided by the Environment Quality Monitoring Division of the State Hydrometeorological Service of the Ministry of Agriculture, Regional Development and Environment, under the ENI SEIS II East project activities.
- Water quality database of Dniester river basin, State Hydrometeorological Service.
Note: The graph shows the distribution of river monitoring sites in nitrate concentration classes (left) and total phosphorus concentration classes (right) for the two river basins of Moldova (Prut basin and Nistru (Dnister) basin), in the Black Sea basin in Moldova (direct tributaries of the Black Sea) and for the whole country, based on the average of the annual mean concentrations for 2017. The number of monitoring sites per river basin is given in parenthesis.
At present, more than half of the sites on rivers in Moldova have low nitrate concentrations (< 2.0 mg N/l) and one third have moderate concentrations (2.0-3.0 mg N/l). Two sites out of 19 have very high concentrations; both are located in the Nistru basin. All six sites on the Prut basin have low nitrate concentrations. The Danube river in Moldova has low nitrate pollution (< 2.0 mg N/l). The River Cogîlnic that flows into the Black Sea is moderately polluted by nitrate (2.0-3.6 mg N/l).
The situation is worse for total phosphorus in rivers. Almost 50 % of river sites in Moldova are moderately to highly polluted. The majority of them lie on the Nistru basin. The least polluted by phosphorus are rivers in the Prut basin. The total phosphorus measured in the Danube river in Moldova demonstrates low nitrate pollution (< 0.1 mg P/l). The River Cogîlnic that flows into the Black Sea is moderately polluted by phosphorus (0.1-0.2 mg P/l).
Indicator specification
Indicator definition
Concentrations of phosphate and nitrate in rivers and total phosphorus and nitrates in lakes.
Units
The concentration of nitrate is expressed as mg NO3-N/l. Total phosphorus is expressed as mg P/l.
Rationale
Justification for indicator selection
Large inputs of nitrogen and phosphorus to water bodies from urban areas, industry and agricultural areas can lead to eutrophication and cause ecological changes that can result in a loss of plant and animal species (reduction in ecological status). This may have negative impacts on the use of water for human consumption and other purposes.
The quality of the surface water environment in terms of eutrophication and nutrient concentrations is the objective of several EU directives such are the Water Framework Directive, the Nitrates Directive and the Urban Waste Water Treatment Directive
Scientific references
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Council Directive 91/271/EEC of 21 May 1991 concerning urban wastewater treatment
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Directive 2000/60/EC of the European Parliament and the Council of 23 October 2000 establishing a framework for Community action in the field of water policy (Water Framework Directive) http://ec.europa.eu/environment/water/waterframework/index_en.html;
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UNECE, 2018, ‘Guidelines for the application of environmental indicators’, description of C11: nutrients in freshwater, United Nations Economic Commission for Europe.
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UNECE, 2018, ‘Guidelines for the application of environmental indicators’, glossary of terms — description of C11: nutrients in freshwater, United Nations Economic Commission for Europe.
Policy context and targets
Context description
National policy context
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Environmental Strategy for the years 2014-2023 and of the Action Plan for its implementation. Republic of Moldova Government Decision No 301 of 24 April 2014.
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Water Law No 727 of 23 December 2011.
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Regulation on the monitoring of systematic evidence on the status of surface water and groundwater (Guideline No 932 of 20 November 2013).
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Regulation on environmental quality requirements for surface water (Government Decision No 890 of 12 November 2013).
International policy context
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Danube River Protection Convention, 1994. Convention on Cooperation for the Protection and Sustainable Use of the Danube (Convention on the Protection of the Danube River, Sofia, 1994).
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There are several EU directives that aim to improve water quality and reduce impacts, the major one being the Water Framework Directive, which requires the achievement of good ecological status or good ecological potential of surface water bodies. In accordance with the EU-Moldova Association Agreement, the country has an obligation to comply with the requirements of these directives.
Targets
National targets
The National Environmental Strategy provides for the implementation of a river basin management system to improve the quality of surface water by 50 % (2023).
According to the Regulation on environmental quality requirements for surface water in Moldova should improve the quality of surface water by one class.
International targets
The UN Sustainable Development Goal 6 target 6.3 aims to achieve, by 2030, improve water quality by reducing pollution, eliminating dumping and minimizing release of hazardous chemicals and materials, halving the proportion of untreated wastewater and substantially increasing recycling and safe reuse globally.
Related policy documents
Environmental Strategy for the years 2014-2023 and of the Action Plan for its implementation. Republic of Moldova Government Decision No 301 of 24 April 2014.
Methodology
Methodology for indicator calculation
In Moldova, the monitoring programme for surface water is based on the Water Law and its regulations transposing the Water Framework Directive. The monitoring of freshwater quality is done by the Environment Quality Monitoring Division of the State Hydrometeorological Service of the Ministry of Agriculture, Regional Development and Environment of the Republic of Moldova. Monitoring data from 19 locations on eight rivers and three lakes was used for the analysis. The frequency of surveillance monitoring was four times a year.
An annual time series for each site was calculated by averaging the values for individual samples per year. Aggregated time series are calculated as the average of the individual annual time series and are calculated for the two major river basins, Nistru (Dniester) and Prut, and basins of two rivers draining into the Black Sea (Dunerea (Danube) and Cogîlnic), as well as for the whole country. Only the time series that were complete after gap-filling are included in the aggregated time series. This is to ensure that the aggregated data series are consistent, i.e. including the same sites throughout the time series. In this way assessments are based on actual changes in concentration and not on changes in the number of sites.
For the present state analysis, the monitoring sites were assigned to different concentration classes, based on the average of the annual mean concentrations for 2017. All sites with data from 2017 were included in the analysis.
The nitrate determination method is based on the regulatory document „SM SR ISO 7890-3: 2006”, namely the spectrometric measurement of the absorption of the yellow compound formed by the reaction of sulphosalicylic acid with the nitrate, followed by treatment with an alkaline solution.
The method for determining orthophosphates is based on their reaction with ammonium molybdate in an acidic medium to form ammonium phosphomolybdate, which subsequently, under the action of ascorbic acid, forms a blue complex known as molybdenum blue.
The total phosphorus determination method is based on the oxido-reduction reaction between the phospho-organic compounds and the ammonium persulphate in an acidic medium to form phosphates, which are subsequently determined by the spectrophotometric method.
Additional information can be found on the environmental indicators public portal of the environmental ministry (1).
Methodology for gap-filling
For time series and trend analyses, only series that were complete after interpolation (i.e. no missing values in the site data series) are used. This is to ensure that the aggregated data series are consistent, i.e. including the same sites throughout the time series. In this way assessments are based on actual changes in concentration, and not on changes in the number of sites.
Methodology references
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EEA, 2005, EEA core set of indicators guide, EEA Technical Report No 1/2005, Office for Official Publications of the European Communities, Luxembourg.
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UNSD and UNEP, 2013, ‘Questionnaire 2013 on environment statistics, section: water’, United Nations Statistics Division and United Nations Environment Programme.
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UNECE, 2018. Guidelines for the Application of Environmental Indicators, Description of C11. Nutrients in freshwater.
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UNECE, 2018. Guidelines for the Application of Environmental Indicators, Glossary of terms – C11. Nutrients in freshwater.
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Regulation on systematic monitoring and recording of surface water and groundwater, HG nr. 932 from 20 November 2013 (2).
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Guidelines for the chemical analysis of surface water’, A.D. Semionova, Guidedrometeoizdat Leningrad 1977.
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Common Implementation Strategy for theWater Framework Directive (2000/60/EC). Guidance document No. 7. Monitoring under the Water Framework Directive (3).
Uncertainties
Methodology uncertainty
No uncertainty has been specified.
Data sets uncertainty
No uncertainty has been specified.
Rationale uncertainty
No uncertainty has been specified.
Data sources
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Data were provided by the Environment Quality Monitoring Division of the State Hydrometeorological Service of the Ministry of Agriculture, Regional Development and Environment, under the ENI SEIS II East project activities.
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Water quality database of Dniester river basin, State Hydrometeorological Service.