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, with screens 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 per year.

The North-Transdanubian Inspectorate of Environment and Water 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 illustrated 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 2010. 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, site: 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 like the Danube water. Pollution by organic matter in the evaluated year was slightly lower than in the year 2009. 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 content once exceeded the groundwater limit value.

Well No. 9413, site: Sérfenyősziget

The water temperature is not influenced considerably by meteorological conditions. The conductivity values after a temporary decrease (in the period 2001 -2003) 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 did not reach the limit values. In case of nitrates slight increase was recorded. Similarly to the year 2009 the iron concentrations did not exceeded the limit value. The content of manganese in the evaluated year was slightly lower in comparison with the previous year, but it was significantly above the limit value for drinking water.

Well No. 9430, site: 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 year. The pH values showed a seasonal fluctuation; in comparison with previous years they slightly increased. The organic matter content shoved a seasonal fluctuation as well, and it is below the limit value. No significant change was recorded in case of phosphates and the ammonium ions content was similar to that in 2009. Nitrates occurred in an amount below the detection limit value. The iron and manganese contents in the ground water are high, and significantly exceed the limit values. Taking into account the long-term development of the manganese content a slight decrease is observed.

Well No. 9456, site: Ásványráró

The groundwater has a medium salt content and stable water temperature with a slight seasonal fluctuation. In the long-term the electric conductivity has slightly increasing tendency. 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 in 2008 and after the decrease has stabilised. The nitrates content is low in long-term. The groundwater has high iron and manganese content, with a seasonal fluctuation. Concentrations of these parameters in the evaluated year 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 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 2010. 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 listed 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.

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 2010. 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 in the year 2010 occurred only at Bodíky waterworks in case of manganese in each sampling and one exceeding was recorded also 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 period 2005-2010 is given in the table “Exceeding of limits of groundwater quality parameters” in the Graphical Appendix of the Slovak National Annual Report in 2010.

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. Differences in these waterworks can be observed in some parameters. At Rusovce waterworks the bicarbonates, calcium, magnesium, chlorides and in last two years the sulphates show slightly higher concentrations; somewhat lower is the content of potassium and nitrates. Higher nitrates concentrations can be seen at Čunovo waterworks during the whole observation period. In the years 2009 and 2010 they have decreasing tendency. However, they are low compared to the groundwater quality limit values. The contents of ammonium ions and phosphates are low in long-term at both waterworks and mostly fluctuates at the level of their detection limits. The organic contamination in last two years, expressed by COD_Mn, decreased to the detection limit. The manganese and iron concentrations are low in long-term. The dissolved oxygen content fluctuate and it slightly increased in last four years. The groundwater quality parameters satisfy the agreed quality limits for groundwater 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 are higher than at other observed objects. The COD_Mn values decreased in last two years below 1 mg.l^-1. Concentrations of manganese, ammonium ion and phosphates are below the detection limits of the applied analytical methods, or just above them in long-term. Iron concentrations in the evaluated year were similar like in the year 2009; the nitrates concentrations were lower. Contents of the other parameters were similar like in the previous year and satisfied the quality limits for drinking water (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 left side of the Danube was not influenced by the damming to that extent like 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 manganese contents. The manganese reaches higher values at Kalinkovo, at Šamorín it mostly occurs below the detection limit. Significant differences are registered only in ammonium ions. Their concentrations are higher at Kalinkovo, but comply with the limits for the groundwater quality. The dissolved oxygen contents in the evaluated year reached maximal values for the entire monitoring period at both waterworks (8.65 mg.l^-1 at Kalinkovo and 7.91 mg.l^-1 at Šamorín). The water temperature, the pH and conductivity values, which showed a slight increase in long term, had stabilised. The concentrations of nitrates, similarly to previous years, oscillated around 5 mg.l^-1. Contamination by organic matter was low. In 2010 all 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 increase in sulphates and chlorides content shows that great part of the water flows to the waterworks from the inland part of Žitný Ostrov area. The water temperature at Gabčíkovo waterworks is more balanced at this waterworks. The pH values after a temporary increase in the period 2006-2008 decreased and they returned to the level of the period 2000-2004. The long-term slight increase of calcium, magnesium, sulphates, bicarbonates and chlorides stopped in the evaluated year. 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. The dissolved oxygen contents are among the lowest. The nitrates concentrations in the period 2008-2010 returned to the level of the years 2002-2005. The sudden change in nitrates content in the years 2005-2007 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). 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.

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, and occasionally chlorides, 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 higher manganese content is characteristic, which exceeds the agreed limit in each determination. Slightly higher are the contents of ammonium ions, iron and bicarbonates, as well as the water temperature values. The dissolved oxygen content is low in long-term at both waterworks, and at Bodíky it is the lowest from among all evaluated waterworks. Slight improvement in redox conditions was registered in the period 2007-2010 at Vojka waterworks (No. 467), where the dissolved oxygen content slightly increased. Concentrations of manganese, ammonium ions, phosphates and iron are low at Vojka and mostly fluctuate below the detection limit. Such low concentrations at Bodíky are characteristic only for phosphates and occasionally for iron (however, in the evaluated year one higher iron concentration of 0.26 mg.l^-1 occurred, which exceeded the limit value for this parameter). 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 drawn from greater 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 wells producing potable water (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). The exceptions are the waterworks at Bodíky and at Kalinkovo. At Bodíky waterworks the manganese exceeds the quality limit in each sampling and occasionally occurs a higher concentration of iron as well (one value in the year 2010) At Kalinkovo waterworks sometimes occurs manganese content, which does not meet the relevant limit. 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 2010. 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 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.

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. At present they are mostly below the detection limits of the applied analytical methods. Only at Bodíky and Kalinkovo they reach higher concentrations, which do not exceed the limit values agreed for these groundwater quality parameters. The content of nitrates is low and the slightly increasing tendency observed since the year 2000 stopped. In waterworks at Čunovo there was even decrease in nitrates to the level in years 1999-2000.

In the evaluated year 2010 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