| Abstract [eng] |
The long-term trend analysis of pollutants is widely applied as an important tool to determine anthropogenic influence, the effectiveness of implemented environmental measures or observation of climate change. Analysis of long-term trend is not an easy task, as it contains of long range of dataset and most important – implementing the right kind of statistical method. In this report Mann-Kendall trend test and Box-and-Whisker plot methods were applied in order to evaluate trends of nutrients and heavy metals. Mann-Kendall test represents non-parametrical statistical method whereas Box-and-Whisker plot refers as Exploratory Data Analysis method. River Nemunas – the longest and with highest flow rate – was chosen as a representative river in Lithuania performing statistical pollution trend analysis. Concentrations of Cu, Cr, Ni, BOD, ammonium nitrogen and total nitrogen have the trend to decreas, whereas concentration of COD increase. Meanwhile concentrations of Zn, Pb, NOx-nitrogen and total phosphorus does not have significant trends. The highest levels of concentration were detected to be bellow Kaunas town. Meanwhile the lowest levels of concentration are near Kulautuva. |
