BORON IN GROUND WATERS OF NICOSIA, CYPRUS ΕΠΙΠΕ Α ΒΟΡΙΟΥ ΣΕ ΥΠΟΓΕΙΑ ΝΕΡΑ ΤΗΣ ΛΕΥΚΩΣΙΑΣ, ΚΥΠΡΟΣ - PDF

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MYKONOS2004 BORON IN GROUND WATERS OF NICOSIA, CYPRUS I. Sarrou, G. Georghiou, A. Charalambides 1, I. Pashalidis Department of Chemistry University of Cyprus, P.O. Box 20537, 1678 Lefkosia, Cyprus, 1 Geological

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MYKONOS2004 BORON IN GROUND WATERS OF NICOSIA, CYPRUS I. Sarrou, G. Georghiou, A. Charalambides 1, I. Pashalidis Department of Chemistry University of Cyprus, P.O. Box 20537, 1678 Lefkosia, Cyprus, 1 Geological Survey Department, Ministry of Agriculture, Natural Resources and Environmnent ABSTRACT Seasonal boron levels in ground waters of Nicosia have been determined and the corresponding data have been compared to previous concentration data and correlated to concentration of other chemical species. According to data evaluation boron levels measured at different time don t differ statistically significant from each other, indicating that basically the geological background governs boron levels and that probably the boron content in Nicosia ground waters is of marine origin. Nevertheless, these boron levels are toxic for boron sensitive crops. ΕΠΙΠΕ Α ΒΟΡΙΟΥ ΣΕ ΥΠΟΓΕΙΑ ΝΕΡΑ ΤΗΣ ΛΕΥΚΩΣΙΑΣ, ΚΥΠΡΟΣ Ι. Σάρρου, Γ. Γεωργίου, Α. Χαραλαµπίδης 1,Ι. Πασχαλίδης Τµήµα Χηµείας Πανεπιστήµιο Κύπρου, Τ.Κ , 1678 Λευκωσία, Κύπρος 1 Τµήµα Γεωλογικής Επισκόπησης, Υπουργείο Γεωργίας, Φυσικών Πόρων και Περιβάλλοντος ΠΕΡΙΛΗΨΗ Στην παρούσα εργασία προσδιορίσθηκε η εποχιακή συγκέντρωση βορίου σε υπόγεια νερά της Λευκωσίας και έγινε σύγκριση των δεδοµένων µε παλαιότερα δεδοµένα και συσχέτισή τους µε συγκεντρώσεις άλλων χηµικών ειδών. Σύµφωνα µε την αξιολόγηση των δεδοµένων τα επίπεδα βορίου που παρατηρούνται σε διαφορετικές χρονικές περιόδους δεν διαφέρουν στατιστικά σηµαντικά, υποδεικνύοντας ότι βασικά το γεωλογικό υπόστρωµα καθορίζει τα επίπεδα βορίου και ότι το βόριο σε αυτά τα υπόγεια νερά είναι µάλλον θαλάσσιας προέλευσης. Εντούτοις, τα επίπεδα αυτά ξεπερνούν τα όρια τοξικότητας για φυτά ευαίσθητα στο βόριο. 1. INTRODUCTION Present and future availability of drinking and irrigation water has become of cardinal importance for the economic and social development of Cyprus. The problem is more serious because Cyprus is a semi-arid region and groundwater is (besides desalination) of primary importance for drinking and irrigation purposes. In arid and semi-arid areas groundwater used for irrigation contains high levels of boron related to the origin and composition of the background lithology [1]. Boron enters into the surface and ground water systems by leaching of rocks and soils, as well as by geothermal releases [2, 3]. On the other hand anthropogenic sources of boron are related to release of boron containing products into water through municipal sewage systems and mining and processing of boron minerals [4]. Boron concentration in irrigation water is of particular interest because of its beneficial and toxic effects in plants. The range between deficiency and toxicity symptoms is narrow, necessitating accurate quantification of solution boron concentrations and pre-treatment of irrigation water, that contains elevated amounts of boron, prior application. Generally, boron levels above 0.3 mg L -1 in irrigation waters for sensitive crops (e.g. citrus trees) and levels above 1.0 mg L -1 for most plants are considered to be toxic [5, 6]. The present paper reports about seasonal variation of boron levels in ground waters of Nicosia, the comparison of these data with previous concentration data and the correlation of boron levels with concentration of other chemical species in the corresponding ground waters. 2. MATERIALS AND METHODS Ground water samples were collected in 1 L plastic bottles from 20 different sites of Nicosia and surroundings (figure 1). Ground water sampling was carried out at three different time periods (Summer 2002, Winter 2002/2003 and Spring 2003) and overall 60 ground water samples had been collected and immediately analysed for ph, electrical conductivity (EC) and cation (Na +, K +, Ca 2+ and Mg 2+ ) and anion (Cl -, NO 3 -, HCO 3 - and SO 4 2- ) concentration. ph was measured potentiometrically by means of a glass electrode (WTW-Model ph537), which was calibrated against ph 4, 7 and 10 standard buffer solutions and the electrical conductivity using a commercially available conductivity meter and electrode (Jenway-Model 4020). Before chemical analysis, the ground water samples were filtered through a 450 nm cellulose acetate filter. Concentration of the cations was determined spectroscopically by means of ICP-OES (Shimadzu ICP-7500). Additionally, determination of sodium and potassium concentration was carried out by flammephotometry (Gallenkamp Flamme Analyser) and calcium and magnesium concentration was analysed by complexometric titrations using EDTA. Determination of anion concentrations was carried out as follows: sulfate by ICP-OES and gravimetry, chloride by means of argentometry - (Mohr Method), nitrate by colorimetry (Lovibond 550) and HCO 3 by acid/base titration. The concentration of boron in solution was determined by ICP-OES or by photometry using the azomethine-h method [7].The precision of the classical methods of chemical analysis was 1%, whereas overall precision of instrumental methods of analysis was estimated to be 5%. Data regarding boron imports were adopted from the annual imports and exports statistics of the Statistical Service of the Republic of Cyprus ( ) and data concerning previous measurements ( ) of boron concentration in the corresponding ground waters were obtained from old reports of the Geological Survey Department. Statistical analysis of the experimental data such as comparison of group means and multivariate analysis was performed using the JMP statistical software package (version 4). Figure 1: Sampling sites of ground waters in which the concentration of boron and other chemical parameters has been determined 3. RESULTS AND DISCUSSION 3.1 Longterm and Seasonal Variation of Boron Levels Figure 2 shows boron concentration data measured in ground waters of Nicosia at different time periods. The data denoted as correspond to boron levels measured in ground waters from different boreholes in the time periode between 1982 and 1984, and the data denoted as summer2002, winter2002 and spring2003 correspond to boron levels measured in ground waters obtained from the same boreholes within this study. In figure 2 the different groups are represented by a means diamond and a quantile box plot. The means diamond provide the mean, as a horizontal diagonal line and the span of boron concentration values corresponding to the 95 % confidence interval for each group, as top and down corners. The quantile box plot shows the median as an inside horizontal line, while the ends of the box indicate the 25 th and 75 th percentiles. The (comparison) circles at the right of the plot provide a graphical presentation of whether the mean values of the concentration measured in the ground waters at different time are statistically different or not. The mean values of the different groups of data are 0.6 ± 0.5, 0.77 ± 0.4, 0.70 ± 0.3 and 0.72 ± 0.4 ppm, respectively. Although statistically not significant, there are small differences between the data obtained at different time periods. The mean and in particular the median value of the previous data are lower than the corresponding values of the recent data. Generally, this phenomenon is observed not only by comparison of group means of boron concentrations in various groundwater systems but also when boron concentrations in a specific groundwater measured at different time period are compared. Figure 3 shows the mean values of boron concentration for different groundwater systems as a function of the sampling period. Despite the restriction of import and use of boron products e.g. washing powders in Cyprus since1974, there is no significant decrease of boron concentration in Nicosia ground waters indicating that the anthropogenic sources of boron play a minor role with respect to boron contamination of the respective ground water systems. The boron content of the ground waters originates basically from the geological background hosting the ground water. The small increases of boron levels observed recently could be attributed to the exhaustive utilization of the groundwater reservoirs, particularly during the recent decades, which has lead to a disturbance of the aquifer systems. Nevertheless, although of natural origin the increased boron levels in Nicosia ground waters are toxic for boron sensitive crops and have to be processed prior application [B] in ppm spring2003 summer2002 winter2002 time periode All Pairs Tukey-Kramer 0.05 Figure 2: Comparison of boron levels determined in ground waters of Nicosia at different time period Furthermore, data in figure 2 indicate that mean boron concentration in ground waters is increased slightly in summer. This is most probably due to exhaustive ground water use and the lack of rainwater intrusion in the groundwater reservoirs during the hot summer-period. Figure 3: Mean values of boron concentration for different groundwater systems as a function of the sampling period 3.2 Multivariate Correlation of Chemical Parameters Figure 4 shows graphically the results of a multivariate correlation performed in order to find any correlation between the various chemical constituents determined in the investigated ground waters. According to the multivariate analysis there is stronger correlation between boron concentration and the concentration of other chemical species of marine origin such as Cl -, Na + and Mg 2+. This indicates that the increased born levels in ground waters of Nicosia are related to seawater remains and is in agreement with the geological evolution of the island and in particular the formation of the area under investigation. The marine origin of the Nicosia ground waters is corroborated also by the fact that the relative concentration of ions found in the respective ground waters corresponds more to the relative concentration of ions found in seawater than to the relative concentration of ions found in a typical ground water (Table 1). Furthermore the linear correlation between chloride and sodium ions (figure 4) indicates on the predominance of marine remains in the Nicosia ground waters. TABLE 1: Chemical analysis of mean groundwater, seawater and Nicosia ground waters chemical species ground water ppm ground water (Nicosia), ppm Seawater ppm Cl ± SO ± HCO ± Na ± Mg ± Ca ± K ± ph [Cl-] [SO4--] [HCO3-] [NO3-] [Na+] [Ca++] [Mg++] [K+] [B] Figure 4: multivariate analysis of chemical parameters determined in ground waters of Nicosia 4. CONCLUSIONS The results obtained from this study lead to the following conclusions: Generally, ground waters of Nicosia contain boron in levels which are toxic for boron sensitive crops Mean boron concentration in the ground waters of Nicosia has slightly increased during the last three decades. This can be most probably attributed to exhaustive utilization of ground water reservoirs during the recent decades and not to release of boron containing products through municipal sewage systems. Boron in groundwaters of Nicosia is basically governed by the geological background and is most probably of marine origin. AKNOWLEDGMENTS This research is supported by Cyprus Foundation for Research Promotion (contract number PENEK-09/2001) and the University of Cyprus. REFERENCES 1. Schachtschabel P., Blume H.-P., Bruemer G., Hartge K.-H., Schwertmann U., in: Lehrbuch der Bodenkunde, F. Enke Verlag, 13 th Edition, Stuttgart Gemici Ü., Tarcan G., Environmental Geology Vol. 43, (2002) 3. Goldberg S., Plant and Soil Vol. 193, (1997) 4. Fox K. K., Cassani G., Facchi A., Schröder F. R., Poelloth C., Holt M. S., Chemosphere. Vol. 47, (2002) 5. Wilcox, L.V., J.Am. Water Works Assoc Vol. 50, (1958) 6. Nable R.O., Banuelos G.S., Paull J.G., Plant and Soil Vol. 193, (1997) 7. Rump H.H., Krist H., in: Laboratory Manual for the Examination of Water, Waste Water and Soil, 2 nd Edition, Weinheim 1992
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