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 from the observation objects were taken 2 times and samples from waterworks 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 in above mentioned observation objects is described in details in the Hungarian National Annual Report in 2008. 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 water quality parameters 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 in last three years had slightly increasing tendency. No substantial change occurred in phosphate ion concentration, or in the content of nitrogen forms in comparison with the previous year. The manganese and iron in the water were in a concentration below the ground water quality limits. 

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 2008 too. Decrease of conductivity values was registered in connection with decrease of sulphate and chloride ions concentration. Concentrations of nitrogen forms, phosphate ions and pollution by organic matter are low, however in nitrates and organic pollution increase were observed in last two years. In 2008 the highest measured concentration of iron in the observed period was recorded (0.80 mg.l^-1). The content of manganese, which is permanently present in concentrations exceeding the limit value in long term, showed decreasing tendency. 

Well No. 9430, locality: Kisbodak

The groundwater in this object has a moderate salt content. The water temperature in the period of observation showed a slight seasonal fluctuation, however it did not followed the changes in air temperature. There was one higher value of electric conductivity recorded in 2008, but the average values could be attributed as stable since 2001. 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 change was recorded in case of phosphates. There was a slight increase of ammonium ions and nitrates registered from among the nitrate forms. From the long-term development point of view decrease of sulphates and calcium can be observed. 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 groundwater has a medium salt content and stable water temperature with a slight seasonal fluctuation. The slightly increasing tendency in electric conductivity values stopped. 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, but the increasing tendency stopped and values began to decrease. The nitrates content was low. The groundwater has high iron and manganese content, with a seasonal fluctuation. Concentrations of these parameters significantly exceeded the drinking water limit values. The content of manganese had slight decreasing tendency.

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 (ZSVS), the Waterworks Company Bratislava (BVS), Slovak Hydrometeorological Institute (SHMÚ) and Ground Water Consulting Ltd. (GWC) were used.

The groundwater quality evaluation for each object included in the joint monitoring was done in the Slovak National Annual Report in 2008. 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 development of observed quality parameters is displayed graphically for each object included in the joint monitoring. The evaluation in the Joint Report is focused mainly on the groundwater 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 (Kalinkovo, S-4) was stopped in 2004 due to technical reasons and it was replaced by the well No. 119 (Kalinkovo, S-9). 

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

On the negotiation of monitoring representatives held in 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, instead of hydrological year. 

Short evaluation of the groundwater 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 2008. 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.

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 2008 is given in the table “Exceedings of limits in groundwater quality parameters” in the Graphical Appendix of the Slovak National Annual Report in 2008. 

Groundwater 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. Higher nitrate concentrations occur at Čunovo waterworks during the whole observation period, but these values are low compared to the groundwater quality limit values for drinking purposes. The content of other observed nutrients is low in long term and mostly fluctuates at the level of their detection limits. The organic contamination in the evaluated year, expressed by COD_Mn, was slightly higher in comparison to the previous year at both waterworks. The manganese and iron concentrations were low. The pH values were fluctuating in 2008 as well. The slight increase of chlorides in 2006 and 2007 did not occurred in the evaluated year and the concentrations returned to the previous level. 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 nitrates concentration considerably fluctuate during the year. The dissolved oxygen content, the nitrates concentrations and the COD_Mn values are higher in comparison with the other waterworks. The concentrations of manganese, ammonium ion and phosphates were below the detection limit of the applied analytical method in 2008. Sporadically higher concentrations of calcium, magnesium, sulphates and hydrogen-carbonates occurred. Contents of the other parameters were similar as in the previous year. No exceedings of quality limits for drinking water (Table 4-3) occurred on this waterworks. 

Left side of the Danube

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

The groundwater quality at waterworks situated on left side of the Danube was not influenced to the same extent by the damming as the quality at the waterworks on right side. The groundwater chemistry at waterworks Kalinkovo (objects No. 116 and 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 potassium, manganese, iron and ammonium ion concentrations – they are higher at Kalinkovo. In 2008 the contents of manganese, ammonium ion and phosphates at waterworks No. 105 in Šamorín were mostly below the detection limit of the applied analytical method again. The water temperature, the pH and conductivity values show slight increase in long term at both waterworks. The dissolved oxygen contents reached higher values in last two years. The tendency of gradual increase of nitrates concentrations stopped. The organic pollution, expressed by COD_Mn value was in 2008 higher than in the previous year. The observed groundwater quality parameters in 2008 satisfied the groundwater quality limits for drinking purposes at both waterworks.

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 are constantly higher. Te long-term slight increase of calcium, magnesium, sulphates, chlorides and hydrogen-carbonates concentrations stopped. The increase in sulphates and chlorides contents show that greater part of water flows to the waterworks 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 changes in the content of nitrates in the period 2005-2008 were caused by change of apparatus for nitrates determination and following calibration and sensitivity alteration. Similar situation occurred at two other waterworks at Vojka and Bodíky as well, which are monitored by the same company - ZSVS. The organic pollution, expressed by COD_Mn is low in long-term (since 2002 the values prevailingly fluctuates below the detection limit of the applied analytical method). From this point of view the oxidizing capacity for organic carbon oxidization got slightly better. Low in long-term are the contents of ammonium ion, phosphates, iron and manganese, which mostly oscillate at the level of detection limits of applied analytical methods. In 2008 every observed quality parameter satisfied the groundwater quality limits for drinking purposes (Table 4-3).

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

The groundwater quality at waterworks Vojka and Bodíky is strongly influenced by local conditions. The groundwater chemical composition is similar; it noticeably differs in few components only. Differences occur in sulphates and nitrates, their values are higher at waterworks in Vojka. The measured values of nitrates in the period 2005-2008 are considered as less representative because of above-mentioned reasons (change of apparatus for nitrates determination). Further differences can be observed in case of ammonium ions, iron, manganese and during the last three years in water temperature as well. Values of these groundwater quality parameters are higher at Bodíky waterworks. The manganese concentrations at this waterworks at every sampling exceed in long term the groundwater quality limit value for drinking water according to Table 4-3. The dissolved oxygen content is low in long-term at both waterworks and it is the lowest from every evaluated waterworks. Slight improving was registered in 2007 and 2008 at Vojka waterworks (No. 467), where the dissolved oxygen content slightly increased. At Vojka waterworks the manganese, ammonium ion and phosphates concentrations, and except one value the iron concentrations as well, were below the detection limits of applied analytical methods in 2008. The COD_Mn values are constantly low at both waterworks, mostly below the detection limit. 

4.3. Conclusions 

According to 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 constantly 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 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 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 sample and twice 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 2008. The groundwater quality at waterworks is stable in long-term. The waterworks Bratislava – Pečniansky les is influenced by 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 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. From among nutrients the phosphates and ammonium ion occur in low concentrations on monitored objects in long term. They are mostly below the detection limits of the applied analytical methods at present. Only at Bodíky and Kalinkovo they reach higher concentrations, which does not exceed the limit values 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 2008 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 purposes

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

IV          – indicating value                    RV       – recommended value

LV         – limit value                            HLV    – highest limit value