A new diatom training set for the reconstruction of past water pH in the Tatra Mountain lakes

Abstract

Lakes located in the Polish and Slovak parts of the Tatra Mountains were included in the Tatra diatom database (POL_SLOV training set). The relationship between the diatoms and the water chemistry in the surface sediments of 33 lakes was the basis for the statistical and numerical techniques for quantitative pH reconstruction. The reconstruction of the past water pH was performed using the alpine (AL:PE) and POL_SLOV training sets to compare the reliability of the databases for the Tatra lakes. The results showed that the POL_SLOV training set had better statistical parameters (R2 higher by 0.16, RMSE and max. bias lower by 0.2 and 0.36, respectively) compared to the AL:PE training set. The better performance of the POL_SLOV training set is particularly visible in the case of Przedni Staw Polski where the curve of the inferred water pH shows an opposite trend for the period from the 1960s to 1990 compared to that based on the AL:PE dataset. The reliability of the inferred pH was confirmed by the comparison with current instrumental measurements.