Nutrients in freshwater

Thematic area - Water

Name of Indicator - Nutrients in freshwater

DPSIR - S - State Indicator

Indicator type - A = descriptive indicator

Definition of the indicator - The indicator shows the concentrations of orthophosphates, total phosphorus, ammonium, nitrates and nitrites in surface waters (rivers and lakes)

Units: Orthophosphates - mg P/l; Total phosphorus - mg P/l; Ammonium - mg N/l; Nitrates - mg N/l; Nitrites - mg N/l.

Policy relevance of the indicator Legal framework includes: - Water Law # 727 from 23.12.2011 ( came into force on 26th of October) - Regulation on monitoring systematic evidence of the surface waters and groundwater’s status (Government Decision # 932 from 20.11.2013) - Regulation on surface water environmental quality requirements (Government Decision # 890 from12.11.2013)

Strategic framework includes: - Environmental Strategy (Government Decision #301 from 24th April 2014);

International framework includes: - Convention on the Protection and Use of Transboundary Watercourses and International Lakes (Water Convention, Helsinki, 1992); - Convention on Wetlands of International Importance especially as Waterfowl Habitat (Ramsar, 1971) - Convention on Cooperation for the Protection and Sustainable Use of the River Danube (Convention for the Protection of the Danube River, Sofia, 1994);

Targets The National Environmental Strategy states that it should be implemented a management system of hydrographical basins in order to improve the surface water quality by 50% (a. 2023) According to the Regulation on surface water environmental quality requirements Republic of Moldova should improve the quality of surface water with one class.

Key questions - Are the concentration of nutrients in the surface waters decreasing?

Assessment

The total phosphorus concentration shows a stable trend for rivers, the values being situates under 0.2 mg/l since 2005 (see Figure #1). The image is quite vice-versa for the concentration of orthophosphates which shows an increasing trend for all tranboundary rivers (see Figure #2). For Dnester River - downstream monitoring station (Olanesti) the total phosphorus concentration in 2005 were very high, but since then the concentration decreased considerably (see Figure# 3).

According to the mean annual monitoring data for surface waters for Danube, Prut Dniester Rivers the nitrites concentration is decreasing in time (see Figure#4), the maximum mean value being calculated for 2009 at the entrance of Prut River in the Republic – s. Sirauti (see Figure#5).

The nitrate concentration in Nistru and Prut Rivers is decreasing, while for Danube River it shows a stable trend (see Figure#6). The nitrate concentration in Nistru River is decreasing in the upstream, while in the downstream it has a stable set of values for the period of the last 10 years (see Figure#7).

The ammonium concentration in rivers is obviously decreasing for all water courses (see Figure#8). Data on concentration of ammonium in Dniester river by monitoring stations shows that in the downstream the concentration of ammonium is higher than in the upstream and middle course of the river. Nevertheless, the trend of concentration of ammonium at Olanesti monitoring station is slowly decreasing by time (see Figure#9).

We observed and assess the situation for 3 lakes – Dubasari, Costesti and Ghidighici for the period 2005-2014. Total phosphorus and orthophosphates in lakes are slightly increasing for 2012 in Dubasari and Costesti reservoirs, while for Ghidighici lake there is an obviously increasing trend for these parameters for 2010, 2012-2013, manly from agriculture activities (see Figure #10 and Figure#11).

The concentration for nitrogen nutrients: nitrites, nitrates and ammonium in lakes is slightly decreasing since 2005 until 2014 (see Figure #12, Figure#13 and Figure#14).

Key messages: The total phosphorus, nitrites, nitrates and ammonium is decreasing in the assessed rivers, while the orthophosphates increase. For assessed lakes nutrients, total phosphorus and orthophosphates decrease, excepting the increasing parameters of total phosphorus and orthophosphates for Ghidighici lake.

Methodology

In the Republic of Moldova the monitoring program for surface waters is based on the Water Law and it’s bylaws transposing the Water Framework Directive. A monthly surveillance monitoring program has been established for tranboundary rivers and Costesti Reservoir, for the other lakes the frequency of surveillance is 4 times per year. The method for determination of nitrates is based on spectrophotometric analyses according to the international standard: SM SR ISO 7890-3:2006. Also, the methods for determining ammonia, nitrites, orthophosphates and total phosphorus are spectrophotometric based on guidelines for surface water. The concentration of phosphates and total phosphorus is expressed as mg of P/liter the concentration of nitrites, nitrates and ammonia is expressed as mg of N/liter.

Uncertainty: The uncertainty is very low because according to national methodology we should have measures at least 4 times per year. Actually we do measures 12 times per years. Recommendations The laboratory performing analyses for surface water monitoring is being accredited since 2004. Nevertheless, there is no automatic water quality monitoring station, which could give us results on the state of affairs each day. Also, due to the fact that the allocated budget for monitoring is smaller than necessary, the monitoring program is being elaborated according to it and it does not cover each waterbody. In order to propose some water quality measures to be taken, there’s a need to know the situation very well, this means there should exist a good monitoring program of the two hydrographical districts delineated in our country. For this we need at least 5 automatic monitoring stations on transboundary rivers. Also, the capacity of the analytical laboratory should be improved by acquisition of modern equipment, staff training in analytical and quality assurance fields.

Данные и Ресурсы

Дополнительная информация

Поле Величина
Администратор Natalia Zgircu
Date noi da
Frecvența de actualizare anual
Instituția sau direcția responsabilă State Hydrometeorological Service