| Popis: |
The qualitative status of groundwater is often underestimated. This is because distinguishing trends of hydrogeochemistry variation linked to anthropogenic pressure from natural trends in groundwater is challenging. The study aims to evaluate the effect of the natural processes on the limits of temporal variability of the natural background level (NBL) in springs draining aquifer units with different vulnerabilities. Shallow groundwater samples of eighteen natural springs were investigated. Statistical analysis and geochemical modelling were used. The results showed that the natural temporal variability limits of HCO3−, Na+, K+, Cl− and SO42− in high vulnerability aquifers were narrower than in moderate and low vulnerability aquifers. This pattern was determined by the stronger buffering effect of carbonate equilibrium, sulphate reduction, and dilution processes on the variation of these major ions in high vulnerability aquifers. Meanwhile, natural temporal variability limits of TDS, Ca2+ and Mg2+ in high vulnerability aquifers were wider than in moderate and low vulnerability aquifers. This pattern was related to the stronger buffering effect of ion exchange on the variability limits of Ca2+ and Mg2+ in springs of moderate and low vulnerability aquifer units than the buffering effect of weaker carbonate dissolution and higher dilution intensity on the variability limits of Ca2+ and Mg2+ in springs of high vulnerability aquifer. The results of this research could be helpful for the reasonable integrated management and effective protection of groundwater resources. |
