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 objects, containing 16 ground water quality observation wells, situated in the upper part of the gravel sediments, and 6 wells that are used for drinking water supply (waterworks). The list of objects is given in Table 4-1. Samples were taken 4 times during the year.

The North-Transdanubian Inspectorate for Environment Protection and Water Management carried out the water quality monitoring in observation wells, Regional Waterworks Companies carried out the water quality monitoring in wells for drinking water supply. Situation of wells included in the ground water quality monitoring are shown in Fig. 4-1. 

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

The ground water quality at above mentioned observation objects is described in details in the Hungarian National Annual Report in 2007. The long-term evaluation of the ground water quality, the detailed evaluation of the chemical composition, tables and diagrams are parts of it. In the Joint Annual Report four selected observation wells were evaluated. 

Well No. 9327, locality: Dunakiliti

Based on long-term data seasonal, periodical variation of certain characteristics (parameters) of water quality was markedly observed in the object No. 9327. The groundwater has low salt content, similarly as the Danube water. Periodicity first of all appears in changes of water temperature, pH, nitrates and chlorides concentrations. Pollution by organic matter shows decreasing tendency. No substantial change occurred in phosphate ion concentration, or in the content of nitrogen forms in comparison with the previous year. The manganese in the water was constantly in a concentration below the ground water quality limits, but contrary to the previous period a slight increase of iron was registered. 

Well No. 9413, locality: Sérfenyősziget

The water temperature was not considerably influenced by meteorological conditions. Slightly decreasing tendency in conductivity values, observed in the previous period, remained with slight fluctuations in 2007 too. Decrease of conductivity was registered in connection with decrease of sulphate and chloride ions concentration and with decrease of calcium concentration. Concentrations of nitrogen forms, phosphate ions and pollution by organic matter are low, and compared to the previous year remained unchanged. The manganese and iron concentrations seasonally fluctuate and the manganese permanently exceeds the limit value for drinking water quality. 

Well No. 9430, locality: Kisbodak

The temperature of this water, which has a moderate salt content, showed a slight seasonal fluctuation, however it did not followed the changes in air temperature. The electric conductivity has not changed and the average values could be attributed as stable. The pH values showed a seasonal fluctuation; in comparison with previous years were lower. The organic matter content shoved a seasonal fluctuation as well, and it is below the limit values in long-term. No significant changes were recorded in case of nitrogen forms and phosphate ion concentrations. There was a slight increase of ammonium ion registered from among the nitrate forms (at the end of 2007). The iron and manganese concentrations in the ground water are high; significantly exceed the limit values. Considering the long-term development of the manganese content a slight decrease is observed. 

Well No. 9456, locality: Ásványráró

The ground water has a medium salt content and stable water temperature with a slight seasonal fluctuation. The slightly increasing tendency in electric conductivity values stopped. In 2007 there were lower pH values recorded in comparison with the previous period. The organic matter content was below the quality limit values for drinking water and did not showed significant changes. The ammonium ion concentrations exceed the limit for drinking water in long-term and their course has increasing tendency. The nitrate content was low. The ground water has high iron and manganese content, with a seasonal fluctuation. Concentrations of these parameters significantly exceeded the drinking water limit values.

4.2. Slovak territory 

The groundwater quality monitoring is carried out on 18 objects on the Slovak territory (10 observation objects and 8 waterworks) – Table 4-2. For purposes of the Slovak-Hungarian monitoring, the data of Western Slovakia’s Waterworks Company (ZVS), the Waterworks Company Bratislava (BVS), Slovak Hydrometeorological Institute (SHMÚ) and Ground Water Consulting Ltd. were used.

The groundwater quality evaluation for each object included into the joint monitoring was done in the Slovak National Annual Report in 2007. Part of the National Annual Report is the Tabular Annex, where the water quality data are processed lucidly for the evaluated period, and the Graphical Annex, where the long-term development of observed quality parameters is displayed graphically for each object included into the joint monitoring. The evaluation in the Joint Report is focused mainly on the ground water quality in waterworks, which are more representative because of their continuous pumping. Data from each well were interpreted in relation to the agreed limits for drinking water, which are presented in Table 4-3. In the long-term evaluation two wells are presented at Kalinkovo site – No. 116 and 119, because the pumping at the well No. 116 was stopped in 2004 due to technical reasons and it was replaced by the well No. 119. 

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

On the negotiation of monitoring representatives held in Gyõr on April 25, 2007 it was agreed, that nitrites, TOC and silicates will be excluded from the groundwater quality parameter list, and that the groundwater quality will be evaluated for the period of calendar year (the evaluation up to the present was related to the hydrological year).

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

In comparison with the previous year, there were no significant changes observed in parameters analysed during the year 2007. The groundwater quality in waterworks is stable in long-term and mostly satisfies the agreed groundwater quality limits for drinking water. Exceedings of agreed limit values occurred at waterworks Bodíky and Kalinkovo in case of manganese, and at waterworks Kalinkovo one times in case of iron.

The groundwater quality in observation objects is more influenced by local impacts. The monitoring results show that agreed limits are exceeded in case of ammonium ion, manganese and iron. Concentrations of all other analysed groundwater quality components in observation objects satisfy the agreed limits for groundwater quality for drinking water.

Detailed evaluation of waterworks and observation objects according to limit values for years 2005 and 2007 is given in the table “Exceedings of Standard’s limits in groundwater quality parameters” in the Graphical Appendix of the Slovak National Annual Report in 2007. 

Ground water quality evaluation at waterworks

Right side of the Danube

Waterworks at Rusovce – No. 102 and at Čunovo – No. 2559

The water quality at waterworks Rusovce and Čunovo is very similar after damming the Danube. Damming the Danube had a great influence on the groundwater quality, primarily on waterworks at Rusovce and in less extent on waterworks at Čunovo. Concentrations of cations, anions and conductivity values had gradually stabilised and they fluctuate in a narrow range at present. The slight increasing tendency of nitrate concentrations continued in 2007 too. Higher nitrate concentrations occur at Čunovo waterworks, but these values are low compared to the groundwater quality limit values for drinking water. The content of other observed nutrients is low in a long term and mostly fluctuates at the level of their detection limits. The organic contamination in the evaluated year, expressed by COD_Mn, was similar to that in the previous year at both waterworks. The manganese and iron concentrations are low, and in case of manganese they mostly fluctuate below the detection limit of the used analytical method. The pH values in 2007 were fluctuating in comparison with the previous period. The chloride content slightly increased in last two years. The groundwater quality parameters satisfy the agreed quality limits for drinking water at both waterworks.

Waterworks at Bratislava No. – 907

Regarding the location of the waterworks No. 907 – Pečniansky les near the Danube the groundwater quality at this object is significantly influenced by changes and chemical components fluctuation in the Danube water. Values of individual parameters, particularly cations, anions, water temperature, dissolved oxygen content and nitrate concentration significantly fluctuate during the year. The dissolved oxygen content, the nitrate concentrations and the COD_Mn values are higher in comparison with the other waterworks. The concentrations of manganese, ammonium ion and phosphates in 2007 were mostly below the detection limit of the applied analytical method. The sodium and chloride concentrations in the evaluated year decreased in comparison with values recorded in the previous year. Lower values were registered for nitrates, iron and COD_Mn as well. No exceedings of quality limits for drinking water occurred (Table 4-3).

Left side of the Danube

Waterworks at Kalinkovo No. – 116 and at Šamorín – No. 105

The groundwater quality at waterworks situated on the left side of the Danube was not influenced to the same extent by the damming as the quality at the waterworks on the right side. The groundwater chemistry at waterworks Kalinkovo (objects No. 119) and at Šamorín (object No. 105) is similar and the course and changes of most quality parameters are similar too. Certain differences exist in calcium, manganese, iron and ammonium ion concentrations. There is a slight increase of water temperature registered in last three years in comparison with the long-term development. There were bigger differences recorded between individual values in 2007 contrary to previous period, when the values were balanced. Since 2004 the dissolved oxygen contents were significantly higher than in the previous period at both waterworks (No. 105 and No. 119). The interpretation of these changes is not unambiguous; they can be connected with the change of waterworks operator. The observed water quality parameters in 2007 satisfied the groundwater quality limits for drinking water at both waterworks, except the sampling in October 2007, when the manganese concentration narrowly exceeded the limit value. The content of manganese, ammonium ion and phosphates in the evaluated year at object No. 105 was mostly below the detection limit of the applied analytical method. The nitrate content was similar to that in 2006. Organic pollution of the ground water expressed by COD_Mn values continually shows a slight decrease.

Waterworks at Gabčíkovo – No. 103

The groundwater quality at Gabčíkovo waterworks differs from the groundwater quality at Kalinkovo and Šamorín waterworks due to the different ground water flow direction. The water temperature at Gabčíkovo waterworks is more balanced. The pH values in years 2005-2006 fluctuated, but in 2007 they became balanced again, although they are slightly higher than in the previous period. In case of the conductivity values, the concentrations of calcium, sulphates, hydrogencarbonates and nitrates a slight long-term increase is registered. At the beginning of the whole observation period their concentrations were lower in comparison with the concentrations at Kalinkovo and Šamorín waterworks. However, they gradually increased and at present they reach higher values at waterworks Gabčíkovo. Increase in sulphates and chlorides contents show that to the waterworks flow greater part of water from the inland part of the Žitný ostrov area. The sodium and potassium concentrations reach only the half of concentration values recorded at Šamorín or Kalinkovo waterworks. Sudden increase of nitrates by 3 mg.l^-1 in 2005 was probably caused by change in methodology of laboratory analysis. Since 2002 the COD_Mn values were mostly below the detection limit of the applied analytical method. From this point of view the oxidizing capacity for organic carbon oxidization got slightly better. Contents of ammonium ion, phosphates, iron and manganese at object No. 103 mostly oscillate at the level of detection limit of applied analytical method. In 2007 every observed quality parameter satisfied the groundwater quality limits for drinking water (Table 4-3).

Waterworks at Dobrohošť – No. 467 and Bodíky – No. 485

The groundwater quality at waterworks Vojka and Bodíky is strongly influenced by the local conditions. The groundwater chemical composition is similar; it noticeably differs in few components only (manganese, ammonium ion and iron). In case of nitrates the concentrations at Vojka waterworks (No. 467) are slightly higher than at Bodíky waterworks (No. 485). In the evaluated period significant differences were registered in case of manganese and ammonium ion concentrations, in less extent in case of dissolved oxygen and iron content. The dissolved oxygen content is low in long-term, and it is the lowest from all evaluated objects. Slight improving in 2007 was registered at Vojka waterworks (No. 467), where the dissolved oxygen content increased. The manganese, ammonium ion and iron concentrations are higher at Bodíky waterworks (No. 485). The manganese concentrations at this object exceed in long term the groundwater quality limit value for drinking water. Decreasing tendency in chlorides and sulphates observed since 2001 stopped and slightly higher concentrations were recorded in comparison with the year 2006. In the evaluated year the manganese, ammonium ion and phosphates concentrations, and except one value the iron concentrations too, were below the detection limit of the applied analytical method at Vojka waterworks. The COD_Mn values are low at both waterworks, mostly below the detection limit. The pH values fluctuated in the years 2005-2006, but they has stabilised in 2007 again. Sudden increase of nitrates in 2005 was probably caused by change in methodology of laboratory analysis. 

4.3. Conclusions 

According to the results of the long-term water quality observations at 16 groundwater quality observation wells on the Hungarian side, it can be stated that the water base of Szigetköz is typically characterised by a higher iron and manganese content. The iron and manganese content continuously exceed the groundwater quality limits on most of the observed wells. In general it can be stated that content of nitrogen form parameters and parameters indicating the presence of organic matter (COD) slightly decreased or it did not changed in comparison to the previous year. The organic pollution is local, particularly of agricultural origin, or in some cases originates from wastewater settlement tanks.

When analysing the groundwater quality data from wells used for drinking water supply it is evident that the ammonium ion and organic matter contents are higher in wells at Győr region. In these wells also the iron and manganese contents exceed the drinking water quality limit values or oscillates around them. The iron and manganese concentrations are lower in waterworks, which are pumped from a bigger depth. The water extracted in waterworks Dunakiliti I., Feketeerdő T-II and Darnózseli I is of satisfactory quality and the groundwater quality is characteristic by high stability. In general the groundwater quality in drinking water producing wells (occasionally after pre-treatment) is suitable for a drinking water supply.

Based on the results of long-term groundwater quality observation on the Slovak territory it can be stated that the observed groundwater quality parameters mostly satisfies the agreed groundwater quality limits (Table 4-3). In case of waterworks exceeding of manganese limit value was recorded at Bodíky waterworks (No. 485) in every sampling and once at Kalinkovo waterworks (No. 119). In case of observation objects exceedings are more frequent and at more objects. Detailed description is given in the Slovak National Annual Report in 2007. The groundwater quality at waterworks is stable in long-term. The waterworks Bratislava – Pečniansky les is influenced by the water quality in the Danube. Contrary to the rest of observed waterworks most of the groundwater quality parameters vary and show seasonality. In the region of waterworks at Rusovce and Čunovo the ground water flow direction has changed, which resulted in groundwater quality improvement at mentioned waterworks. The groundwater quality at Kalinkovo and Šamorín is influenced by surface water infiltration from the Danube and reservoir. The groundwater quality at Gabčíkovo waterworks differs from the other waterworks due to the prevailing groundwater flow direction coming from the inland area. The ground water quality at Vojka and Bodíky waterworks is significantly influenced by the local conditions. At Bodíky the manganese content reaches higher values, more often exceeds the agreed groundwater quality limit. Based on long-term measurements it can be stated that the organic pollution characterised by COD_Mn decreased during the observed period at every object. From among the nutrients the phosphates and ammonium ion occur in low concentrations on monitored objects in long term. They are mostly below the detection limit of the applied analytical method at present. Only at Bodíky and Kalinkovo they reach higher concentrations, which does not exceed the limit agreed for these groundwater quality parameters. Approximately since 2000 a slight increase of nitrates concentrations is registered, but their content is permanently low. In the evaluated year 2007 no considerable changes of the groundwater quality were registered. The groundwater chemical composition in observation objects is similar to the groundwater chemical composition of the waterworks in their neighbourhood. The groundwater quality in observation objects mostly reflects local influences. 

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

Table 4-3: Groundwater 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