engleski

Effect of nitrates on underground water resources-analysis by RAPS method

Usual drinking water quality analysis is used to determine amount of the nitrates since excessive concentrations of nitrate-nitrogen or nitrite-nitrogen in drinking water have a negative impact on health.Regardless their concentrations are under or below the maximum allowed concentration, special attention should be devoted to the seasonal changes of nitrate concentration. Such changes can be caused by natural or by anthropogenic impacts. Before establishing the possible connections or even correlations to the nitrate concentration changes and mentioned impacts, it is necessary to determine seasonal increases, decreases, and similar deviations within analyzed time period. Such period has duration from one month up to one year, or even during longer. Most often used statistical methods, i.e. trend analysis, determining the correlation between two or more variables, etc., enable a smooth analysis, but sometimes they can lead to false conclusions, especially in case of the insignificant value of the regression coefficient. Using the Rescaled Adjusted Partial Sums method (RAPS) eliminates such a subjective analysis and foregoing conclusions. By using it, small systematic and random changes can be overcome, and errors and variability in the analyzed time series can be seen by graphic representation of the calculation of RAPS values for analyzed time series. This paper showed implementation of RAPS method for the case study of nitrate time series of well-field Bartolovec, which has a crucial importance for water supply of the Varaždin city in Croatia.

Nitrates ; time series analysis ; RAPS ; Varaždin ; water supply

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