UV/VIS spectroscopy as a method to characterize well water quality. [UV/VIS-spektroskopi som metod att karakterisera brunnsvattenkvalité]

Abstract

The applicability of UV/VIS spectroscopy for the characterization of well water quality was studied by analyzing 219 private wells from sparsely populated areas of Finland. In addition to conventional water quality indicators, such as conductivity, nitrate and DOC, a series of UV/VIS spectroscopic parameters were determined: A-224, A-254, A-280, A-365, A-436, the area under 250–350 nm, the area under 250–500 nm, SUVA-254, Molar Absorbance-280, Specific Color, A2/A3 and A2/A4, in order to find the most proper surrogate for the organic matter amount and the best indicator of organic matter quality. Three parameters, A-254, A-280 and the area under 250–350 nm were found to be applicable as surrogates for conventional aggregate organic matter indicators, giving rough approximations of organic content in well waters. A-224 can be used to estimate roughly the nitrate concentration in well water samples. A2/A4, SUVA-254 and Molar Absorbance-280 correlated positively with the high molecular weight fraction of NOM and therefore indicate surface water percolation or soil organic matter leaching into the wells. A2/A4 was found to be the most appropriate bulk spectroscopic parameter for the characterization of NOM structure and origin from wells with low and high dissolved organic matter content.