PART 4

 

Ground Water Quality

4.1. Hungarian territory

The subject of the joint ground water quality monitoring on the Hungarian side consists of 22 wells, from among 16 objects are ground water quality observation wells, situated in the upper layer of the gravel sediments, and 6 wells are used for drinking water supply (Tab. 4-1).

Samples were taken 4 times during the year. In 2003 no sample were taken in case of the Darnózseli I drinking water well. Dissolved oxygen measurements in ground water quality observation wells were done as well.

The water quality monitoring in observation wells was carried out by the North-Transdanubian Authority for the Environment Protection, the water quality monitoring in wells for drinking water supply were carried out by Regional Waterworks Companies. Wells included in the ground water quality monitoring are situated on the Fig. 4-1.

  Table 4-1: List of monitoring objects on the Hungarian territory

In compliance with the point 1 of the Recommendations of the Joint Annual Report in 1999 long-term evaluation of the ground water quality since 1992 has been carried out in the 2003 National Annual Report. The detailed evaluations, tables and graphs of ground water quality data are part of the Hungarian National Report as well.

The ground water quality in case of the selected four observation wells on the Hungarian side was as follows.

Well No. 9327, locality: Dunakiliti

On the basis of long-term data the seasonal, periodical variation of water quality was markedly observed in the ground water observation well, the water of which had low salt content, similarly to the Danube water. Periodicity appears mainly in changes of water temperature, dissolved oxygen, conductivity, pH and nitrate ion concentrations. Alongside with this slight increase of sodium and chloride concentration was recorded. No substantial change occurred in the organic contamination, phosphate ion concentration and in content of nitrogen forms in comparison to the previous year. Iron in the water was detected in a concentration below the ground water quality limits, while the manganese concentration, which increased in comparison to the previous year, exceeded these limits in the second half of the year.

Well No. 9413, locality: Sérfenyősziget

In the year 2003 the meteorological conditions did not affected the water temperature significantly. Seasonal fluctuation was monitored in pH values and sodium, iron and manganese contents. The conductivity values, which refer to the salt concentration in the water, fluctuated more significantly; on the basis of average values a decreasing tendency can be presented. The content of potassium, magnesium and chloride was below ground water quality limits, with further decreasing tendency. The calcium concentration in 2003 was present in lower concentration, however it exceeded the ground water quality limits. The concentration of organic matter showed a slight increase. From among the nitrogen forms limit values were measured in case of nitrite ion at one occasion, while the ammonium ion and nitrate ion concentrations as well as the organic contamination remained below the limits. In case of nitrates limited fluctuation and decreasing tendency was observed. The iron content slightly increased and concentration exceeding the ground water quality limit was measured at one occasion. The manganese content seasonally fluctuated and permanently exceeded the limit value.

Well No. 9430, locality: Kisbodak

The temperature of the water with a moderate salt content was lower in comparison with the previous year; the fluctuation was of lower rate and it did not followed changes of air temperature. The continuous decrease of salt content stopped; values were stable in comparison to the previous year. An increase was observed in organic contamination and in phosphate concentration. Values of nitrite and nitrate ions were similar to values of previous year, with maximum observed in spring. There was a decrease recorded in content of ammonium ion and sulphates. Considering the drinking water use only the ammonium ion content could be objected. The iron and manganese concentrations in the water were high. The iron content fluctuated significantly throughout the year, while the manganese content showed a seasonal fluctuation.

Well No. 9456, locality: Ásványráró

The conductivity values of the water with a stable, slightly seasonally fluctuating water temperature and medium salt content, did not changed significantly in comparison with the previous year.

The organic material content was below the ground water quality limit values and presented a slight seasonal fluctuation; no significant change occurred in values compared to the previous year. From among the nitrogen forms the ammonium ion concentration exceeded the limit value, with maximum in the summer period. The slight increasing tendency stopped. The nitrite and nitrate contamination was not typical in this water. The iron and manganese content demonstrated a seasonal fluctuation over the limit concentrations.

4.2. Slovak territory

For purposes of the Slovak-Hungarian monitoring data of the Western Slovakia’s Waterworks Enterprise (ZVS), the Waterworks Enterprise Bratislava (BVS), Slovak Hydrometeorological Institute (SHMÚ) and Ground Water Consulting Ltd. were used. The objects of Waterworks Enterprises are used for drinking water supply; the other objects are observation wells (Tab. 4-2).

The evaluation for every well included in the joint monitoring, similarly to the previous years, was done for period of eleven years (1.10.1992-31.10.2003) in the National Annual Report. The evaluation in this report is focused mainly to the ground water quality in waterworks, which are more representative because of their continuous pumping. All data from each well were interpreted in relation to the agreed limits for drinking water presented in Tab. 4.3.

Since April 1, 2004 a new Ordinance No. 151/2004 of the Slovak Ministry for Public Health was set, which completely transposed the EU Directive No. 98/83/EC from November 3, 1998 describing the water quality limits for human consumption. The notice “SK” in the table 4.3 labels parameters where Slovak national standard prescribes other values.

Table 4-2: List of monitoring objects on the Slovak territory

Short evaluation of the ground water quality in monitoring objects included in the data exchange

In comparison to the previous year there were no significant changes in the parameters observed during the hydrological year 2003. Long-term evaluation was done in the Slovak National Annual Report in 2003 for eleven years period, comparing the data from all monitored objects with the agreed limit values for ground water quality. Ground water quality at drinking water sources is very stable in long term and satisfies the agreed ground water quality limits. The only exceptions are the waterworks Bodíky (No. 485), where manganese concentrations 17 times and ammonium concentration once exceeded the limit value during the whole observation period, and the waterworks Rusovce (No. 102), where sulphate concentration once exceeded the limit value (year 1992). (For details look into the table “Exceedings of the Standard’s limits in ground water quality parameters” in the Graphical Appendix of the Slovak National Annual Report in 2003.)

The ground water quality in observation objects is more influenced by local impacts. From the table “Exceedings of the Standard’s limits in ground water quality parameters” in the Graphical Appendix of the Slovak National Annual Report in 2003 results, that agreed limit in case of ammonium concentration was more frequently exceeded at object No. 899, while occasionally it was exceeded at objects 87, 329, 872 and 888. In case of nitrite concentration the limit values were exceeded more frequently at object No. 170, while occasionally at objects No. 234 and 872. In case of manganese the limit value was exceeded more frequently at object No. 899, occasionally at objects No. 170 and 3. The iron concentrations overrun the limits at objects No. 170 and 872, occasionally at objects No. 262, 265 and 87. Sporadically occur values exceeding limit concentration for magnesium, COD_Mn and chlorides. Concentrations of all other observed ground water quality components at monitored objects satisfy the limits for ground water quality.

Ground water quality evaluation at waterworks for drinking water supply.

Right side of the Danube

(Waterworks at Bratislava No. – 907, at Rusovce – 102, at Čunovo – 2559)

The water quality on waterworks at Rusovce and Čunovo is very similar. Damming the Danube had a great influence on the ground water quality due to the changed infiltration conditions and changed ground water flow direction, especially at the waterworks Rusovce. After the damming the concentration of cations (Na, Ca, Mg) and anions (Cl, SO₄, HCO₃) significantly decreased, which resulted in decreased of conductivity, which is permanent. Similar process, but in less extent was observed at the waterworks Čunovo, mainly in case of sodium, chlorides and sulphates. At Rusovce there is a slight increasing tendency of pH values detected.

In the period of 1998-1999 the ground water quality has stabilised and the cations and anions fluctuate in a narrow range, in case of calcium and magnesium there is a slight increase observed, while in case of sulphates and hydrocarbons the decrease continued. On both waterworks the nitrate concentrations, as well as the organic contamination, expressed by COD_Mn and TOC, decreased and got stable.

The situation at the waterworks No. 907 at Bratislava differs. Values of respective parameters fluctuate a lot during the year, except the pH value. The waterworks is situated near the Danube and concentrations of observed parameters follow the fluctuation of these parameters in the Danube. Based on the measured values it can be stated that increase of magnesium concentration, and decrease of sulphates, manganese, phosphates and organic contamination occurred.

Left side of the Danube

(Waterworks at Kalinkovo No. – 116, at Šamorín – 105, at Dobrohošť – 467, at Bodíky – 485, at Gabčíkovo – 103)

The ground water quality at waterworks situated on the left side of the Danube was not influenced to that extent like the quality at the waterworks on the right side. The ground water quality at the waterworks No. 116 at Kalinkovo and No. 105 at Šamorín is similar. Some differences (at Kalinkovo slight increase, at Šamorín slight decrease) exist in calcium, magnesium and hydrocarbonate concentrations and conductivity values (wider range at Kalinkovo). The manganese concentrations at Kalinkovo fluctuate around 0.2-0.3 mgl^-1. On both waterworks the concentrations of nitrates decreased, however since 2001 there is a slight increase. Concentration of sulphates decrease on both waterworks. The concentrations of silicates slightly increased, the increase since 2002 is more evident. The COD_Mn values in 2002-2003 slightly decreased on both waterworks. TOC at Kalinkovo increases, at Šamorín the increase of TOC stopped in 2000 and the concentrations have begun to decrease. In comparison to the previous period the average water temperature at Kalinkovo waterworks in the period 2001-2003 increased by 1 °C.

The Gabčíkovo waterworks is situated in the area drained by the tailrace canal and the water comes to the wells from the inland area. The conductivity, content of dissolved solids, chlorides, sulphates, sodium, potassium and nitrates slightly increase in long term. This fact shows that the amount of ground water coming from the inland area gradually increases. Concentrations of silicates are higher in comparison to waterworks Kalinkovo and Šamorín, moreover since 2002 there is additional slight increase. The oxygen content is low, but the nitrate concentration slightly increases and the TOC and COD_Mn values decreased to 1 mgl^-1. From this point of view the oxidative capacity for organic carbon oxidation slightly improves. The iron content is below the detection limit, however the manganese content rarely exceeds the given limit.

The ground water quality at waterworks No. 467 – Vojka and No. 485 – Bodíky is strongly influenced by the local conditions. Although the waterworks are close to each other, based on the measurements it can be stated that tendencies in ground water quality parameters are different: decrease of conductivity, calcium, manganese and sulphate concentrations at Bodíky waterworks; increase of conductivity, calcium, manganese, sulphate and hydrocarbonate concentrations at Vojka waterworks. At waterworks Bodíky the ammonium concentrations fluctuate in a wide range from 0.05 to 0.57 mgl^-1, however a slight decrease in 2002-2003 could be observed. The manganese concentrations fluctuate mainly from 0.2 to 0.8 mgl^-1. Nitrate concentrations decrease on both waterworks during the whole monitoring period, however since 2001 a slight increase is observed. Concentrations of COD_Mn and TOC slightly decreased on both waterworks during last two years. Concentrations of silicates slightly increase during the observed period on both waterworks.

4.3. Conclusions

As a conclusion it can be stated that the basic physical and chemical parameters, cations, anions and oxygen regime parameters satisfies the agreed ground water quality limits at all monitoring objects. The nutrient content satisfies the agreed limits in long term as well, except the nitrates in object No. 170 during the period 1994-2000, while in 2001-2003 the situation got better, and ammonium content, particularly in object No. 899. The iron and manganese contents satisfy the agreed limit on most of the monitored objects, however manganese content frequently exceeds the given limit in objects No. 116, 485, 899 and 262 and the iron content exceeded the limit in objects 170 and 872, occasionally in objects No. 262 and 234.

Summarizing the results of the long-term water quality observations of 16 groundwater quality observation wells on Hungarian side it can be stated that the water base of Szigetköz is typically characterised by higher iron and manganese content. The manganese content was permanently over the groundwater quality limit at 12 wells, while the iron concentration exceeded the limit value at 9 wells.

In 2003 further changes in ground water quality could be observed at certain wells, since the content of components – presumably indicating contamination of agricultural origin and waste water – like nitrogen forms and organic material changed from well to well. However, their content was generally lower or it did not changed in comparison to the previous year.

Changes in ground water quality at some places reflect an integrated effect of the transformations occurred in the region, in which the changed ground water flow directions, affected by the Szigetköz water supply, also played role.

The ground water quality of drinking water producing wells could be characterised by a high degree of stability. The drinking water producing wells in the Győr region prove a small scale of manganese and ammonium contamination. The salt content, the iron and manganese concentrations were higher in wells at Győr-Révfalu water source, than in wells at Győr-Szőgye, which were pumped from bigger depth. In general the ground water quality in drinking water producing wells – occasionally after pre-treatment – is suitable for drinking water supply.

Limits for drinking water quality used for evaluation in the frame of joint monitoring are given in the following table:

 Table 4-3: Ground water quality limits for drinking water

EU-European standard, SK-Slovak standard, H-Hungarian standard

IV          – indicating value                    RV     – recommended value

LV         – limit value                            HLV    – highest limit value