State and impacts
- Surface waters are in good condition.
- The rivers are contaminated in areas around big settlements, especially those with no treatment plants for wastewater.
- Main pollutants are domestic sewage, industry and agriculture.
- Improvement of river water is due to the transition to a market economy and reduction of the large industrial facilities and pollutants.
Figure 1. Categorisation of sites for the period 2001-2007 and
Figure 2. Change of the concentration of the main indicators: NH4-N, NO3-N, DO, COD-Mn, BOD5, PO4 (1990 = 100%) for the period 1990-2007.
Surface waters in Bulgaria as a whole are in good condition. Transition to market economy and the decline in production from industry and agriculture has led to a reduction in pollutants discharged into water, including reducing the loads of major nutrients (nitrogen and phosphorus). As a result, nearly 75 % of the length of rivers in the country meet the standards for good quality. The improvement of water quality started 1998 - there is a clear trend of sustainability and slight improvement of all indicators for water quality between 1998 and 2007.
On the national level, we applied the same thtt indicators for chemical status of surface waters as on the European level: average concentrations of dissolved oxygen (DO), BOD5 (BOD5), Mn (COD-Mn), ammonium (NH4 - N) and nitrate (NO3-N) nitrogen, phosphate (PO4). The categorisation of surface water was done according to Ordinance No 7/1986 - benchmarks and standards for determining the quality of running surface water in Bulgaria. There is a clear tendency of an increasein waters in good chemical status (I category) – more than 80 % of stations. There is an exception only for ammonium nitrogen concentration – 40 % of sampling stations is in I category, but the standard in Bulgaria (<0.1 mg/l) is more strict than in the EU (<0.2 mg/l).
Groundwater - water quality
- Groundwater quality assessment for 2007 has been carried out in compliance with European Water Framework Directive by groundwater bodies (GWBs) and by River Basin Districts.
- The results of the chemical analyses had been made were compared with the Groundwater Quality Standards according to the Bulgarian Regulation N-1 dated 10.10.2007 for exploration, use and protection of groundwater.
- The GWBs were identified as being at risk in 2007 for different pollutants but the most considerable were the exceedings of the Nitrate Standard.
- Statistical calculations of Nitrate concentration have been carried out for the time period 1993-2007 (medians, 25 percentile, 75 percentile, minimum and maximum). The highest median values were determined for groundwater in the Black Sea River Basin District.
- Groundwater status was estimated as mean values of Nitrate contents of all the country for a four-year period, corresponding to the different groundwater monitoring types of points.
- Trends analyses of the nitrate content mean values were carried out for two time periods – 2000-2003 and 2004-2007.
Groundwater - status assessment:
Figure 3. Nitrate concentration in groundwater at Black Sea River District.
Figure 4. Indicator on status.
Figure 5. Average Nitrate concentrations in groundwater [mg/l] in time period 2004-2007.
Figure 6. Trend classes between previous and current monitoring period for Nitrates – time periods 2000-2003 and 2004-2007.
- Nitrates are the main pollutant of groundwater in the country.
- Groundwaters were classified by nitrates content in four quality classes for the average nitrate concentrations in groundwater
- In compliance with the Development guide for Member State reports - Status and trends of aquatic environment and agricultural practice- under ‘NITRATES’ DIRECTIVE (91/676/CEE), the average and the maximum values of the nitrate content per every groundwater sampling site were determined for time period 2004-2007. The map with average nitrate concentration is shown her.
- Groundwater status analysis by Nitrates (Average values for time period 2004-2007) was carried out consider the monitoring station types:
Type 0 - Phreatic groundwater (shallow): 0-5 m (inclusive phreatic springs)
Type 1 – Phreatic groundwater (deep)
Subtype 1a – 5-15 m
Subtype 1b – 15-30 m
Subtype 1c - >30 m
Type 2 – Captive groundwater
Type 3 - Karstic groundwater (inclusive Karstic springs)
- The results of Nitrates analysis by station type show predominance of the average concentrations below 25 mg/L for all station types except the Karstic groundwater, where 33,3% were below 25 mg/L, but another 33,3% were above 50 mg/L. The very high vulnerability of the Karstic groundwater (inclusive Karstic springs) is shown.
Groundwater - trend assessment:
A map with Nitrate trend classes between the previous (2000-2003) and the current (2004-2007) monitoring period (in compliance the Nitrate Development guide) was prepared and is shown here.
The results of trend analyses by monitoring station types shows prevalence of trend of decrease in type 0 phreatic (shallow) groundwater; for type 1, deep phreatic groundwater – subtypes 1a and 1b - slow predominance have increasing trends, while decrease trends are predominantly detected in subtype 1 c and type 2 - Captive groundwater. Increasing trends predominate for Type 3 - Karstic groundwater (inclusive Karstic springs) with 64,71%.
Groundwater - water quantity
Groundwater quantity state assessment for 2007 has been carried out by monitoring stations – well levels and spring flows trends.
Groundwater quantity trend assessment for time period 2003-2007, has been carried out by monitoring stations – well levels and spring flows trends.
Indicator on trends:
Figure 7. Increase trend in the spring flows (2003–2007).
Figure 8. Decrease trend in the spring flows (2003–2007).
Figure 9. Increase trend in the wells’ levels (2003–2007).
Figure 10. Decrease trend in the wells’ levels (2003–2007).
Evaluation of the groundwater quantitative status and description of the trends. Groundwater quantitative status.
Very big spatial variety in groundwater quantity status was detected during 2007, but with predominant trends of decreasing of groundwater resources, has been observed in 61 monitoring points – 60 % of the points representative for the different groundwater bodies.
The month average values of the spring flows have been below the average month rates in 71 % of the groundwater basins in the main part of the year.
For the groundwater levels in the wells a big spatial variety also was observed considering the corresponding normal average month rates and multi annual average month values, bur with prevailing trend of decrease, detected in 37 observed points or 55 % of the cases.
Description of the groundwater quantitative trends:
The trends in the spring flows and the groundwater levels in the wells in the time period 2003-2007 were established to be predominantly positive.
Increase was detected at 51% of GWBs for the spring flow, and also rise of groundwater level was measured in 54 % of the observed cases (35 wells).
Further national information
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