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. In 2009 the observation of ground water quality at object No. 9435 at Arak was terminated due to technical reasons. This object was replaced by the observation well No. 9544 at Halászi, which is situated close to the original object.

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 2009. 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 is markedly observed in the object No. 9327. Periodicity first of all appears in changes of water temperature, pH and nitrates concentrations. The groundwater has low salt content, similarly as the Danube water. Pollution by organic matter in last four years had slightly increasing tendency, which stopped in the evaluated year. No substantial change occurred in phosphate ion concentration, or in the content of nitrogen forms in comparison with the previous year. The manganese content was below the groundwater quality limit value, but the iron exceeded the limit value in both samples.

Well No. 9413, locality: Sérfenyősziget

The water temperature is not influenced considerably by meteorological conditions. The conductivity values after a temporary decrease (app. since 2001) has stabilised on certain level. The decrease of conductivity values was registered in connection with decrease of sulphate and chloride ions concentrations. The content of nitrogen forms, phosphate ions and pollution by organic matter were low. Contrary to the year 2008 the iron concentrations did not exceeded the limit value. The content of manganese, which slightly decreased in previous years, showed increasing tendency in the evaluated year and significantly exceed the limit value for drinking water.

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. The electric conductivity was similar to that in previous years. 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 contrary to its higher content in the period 2007-2009 it is below the limit value in long-term. No significant change was recorded in case of phosphates and the ammonium ions content was similar to that in 2008. Nitrates occurred in an amount below the detection limit value. The iron and manganese concentrations in the ground water are high, and significantly exceed the limit values. Regarding 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 limit values for drinking water and did not show significant changes. The ammonium ion concentrations exceed the limit for drinking water in long-term, but the increasing tendency stopped and after the decrease has stabilised.. 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, similarly to the previous period of observation.

4.2. Slovak territory

The groundwater quality monitoring on the Slovak territory is carried out on 18 objects (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 2009. 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 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 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 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 groundwater quality in monitoring objects included in data exchange according to the Agreement

In comparison with the previous year, there were no significant changes observed in parameters analysed during the year 2009. The groundwater quality in waterworks is stable in long-term and mostly satisfies the agreed groundwater quality limits for drinking water. Exceeding 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 period 2005-2009 is given in the table “Exceeding of limits of groundwater quality parameters” in the Graphical Appendix of the Slovak National Annual Report in 2009.

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 on waterworks at Rusovce and in less extent on waterworks at Čunovo. Concentrations of cations, anions and conductivity values had stabilised gradually and at present they fluctuate in a narrow range. At Rusovce the calcium, magnesium and chlorides show slightly higher concentrations; somewhat lower is the content of potassium and the pH value. In comparison with the Rusovce waterworks 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, decreased in comparison to the previous year at both waterworks. The manganese and iron concentrations were low. The dissolved oxygen contents significantly vary and they slightly increased in last three years. The groundwater quality parameters satisfy the agreed quality limits for drinking water at both waterworks.

Waterworks at Bratislava No. – 907

With regard to the location of the waterworks No. 907 – Pečniansky les, near the Danube, the groundwater quality at this object is significantly influenced by changes and fluctuation of chemical components 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 COD_Mn values recorded in 2009 were the lowest since starting the monitoring. Similarly to the year 2008 the concentrations of manganese, ammonium ion and phosphates in the evaluated year were below the detection limit of the applied analytical method. Concerning the nitrates and iron concentrations the values recorded in 2009 were the maximal values during the observation period, however the iron occurs in low concentration in long-term at this waterworks. Contents of the other parameters were similar as in the previous year. In the evaluated year no exceeding 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 by the damming to that extent as the quality at the waterworks on the 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 groundwater quality parameters are similar too. Little differences exist in case of potassium, manganese and iron. These parameters reach higher values at Kalinkovo. Significant differences are registered only in the case of ammonium ion, which concentrations at Šamorín waterworks are below the detection limit, contrary to Kalinkovo waterworks, where they are higher. The dissolved oxygen contents reach higher values in last three years at both waterworks. The water temperature, the pH and conductivity values show slight increase in long term. The concentrations of nitrates were similar as in the year 2008. In the case of COD_Mn concentrations one higher value of 2.13 mg.l^-1 occurred at Kalinkovo waterworks, however it did not exceed the limit value. During the observation period the manganese and iron concentrations several times exceeded the limit values at Kalinkovo. In 2009 every observed groundwater quality parameter 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 in 2009 decreased and they returned to the level of the period 2000-2004. The long-term slight increase of calcium, magnesium, sulphates, chlorides and hydrogen-carbonates concentrations stopped. The increase of sulphates and chlorides show that greater part of water flows to the waterworks from the inland part of the Žitný ostrov area. The sodium and potassium concentrations are the lowest of all observed object and reach only the half of concentration values registered at Šamorín or Kalinkovo waterworks. Sudden change in the content of nitrates in the period 2005-2008 was 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 - ZVS. 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 2009 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 on both waterworks; it noticeably differs in few components only. Slight differences occur in sulphates and nitrates, which 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). At Bodíky waterworks the manganese contents are higher in long-term, slightly higher are the contents of ammonium ions, iron and hydrogen-carbonates, as well as the water temperature values. 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 among the evaluated waterworks. Slight improving was registered in the period 2007-2009 at Vojka waterworks (No. 467), where the dissolved oxygen content slightly increased. At this waterworks the manganese, iron, ammonium ion and phosphates concentrations in 2009 were below the detection limits of applied analytical methods. The COD_Mn values are constantly low at both waterworks, frequently below the detection limit.

4.3. Conclusions

According to results of long-term water quality monitoring at 16 groundwater quality observation wells on the Hungarian side, it can be stated that the water base of Szigetköz is typically characterised by higher iron and manganese content. The iron and manganese content constantly exceed the groundwater quality limits on most of observed wells. In general it can be stated that the 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 it 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 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 occasionally it occurs at Kalinkovo waterworks (No. 119), in the year 2009 it did not occur. In case of observation objects exceeding of limit values is more frequent and it occur at more objects. Detailed description is given in the Slovak National Annual Report in 2009. 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 these 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 2009 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 purposes 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