Groundwater quality as a source for irrigation in Strumica valley, Republic of Macedonia

B. Kovacevik*, S. Mitrev, B. Boev, I. Karov, V. Zajkova Panova
Laboratory for Plant Protection and Environment, Goce Delcev University of Stip, Krste Misirkov, 2000 Stip, Republic of Macedonia

Abstract. The quality of groundwater was investigated for possible agriculture pollution in the traditional agriculture region of Strumica, situated in the southeast part of the Republic of Macedonia. Almost 200 samples of water from boreholes in 14 different points were collected and analyzed by relevant standard methods for a total content of Na+, K+, Ca2+, Mg2+, NH +, Cl-, HCO -, SO 2-, NO -, NO -, and PO 3-. The results showed that groundwater in the studied area is generally neutral to slightly alkaline. The abundance of the major ions is Mg2+>Ca2+>K+>Na+ and HCO ->Cl->PO 3->SO 2-. Concentration range of the main 344 cations Na+, K+, Ca2+ Mg2+ and NH + is 1.40 – 36.71mg/L, 0.68 – 354.44 mg/L, 7.43 – 411.18 mg/L, 1.07 – 96.14 mg/L and < LOQ (limit of quantification) – 55.89 4 mg/L, respectively. Regarding anions Cl-, HCO -, SO 2-, NO -, NO -, and PO 3- concentration range is 4.19 – 614.31mg/L, 0.04 – 750.97 mg/L, < LOQ – 300.45 34324 mg/L 0.14 – 284.44 mg/L, < LOQ – 35.85 mg/L and < LOQ – 7.80 mg/L, respectively. A multivariate statistical analysis is performed to evaluate the possible interrelationship within a set of variables. Statistical and hydrochemical analysis suggest that the quality of groundwater is mainly affected by the geological composition of the area. Factor analysis (FA) revealed five significant factors of 14 variables and account for 71.54 % of the total variance. Although nitrates are considered a significant source of widespread groundwater contamination, when it comes to agricultural areas the result didn’t show any severe contamination except in the periphery of the valley which is considered to be related to the thickness of the basal lithozone represented by sandstones and the shallow aquifers.