Major and Trace Elements in Water and Suspended Matter of the Northern Dvina River and Their Annual Discharge into the White Sea
Résumé
The results of continuous four-year-long investigations (from May 2015 to April 2019) of the elemental composition of water and suspended matter in the Northern Dvina River are given. Water was sampled every month at two sites in the lower reaches of the river. More than 50 major and trace elements are determined in water filtered through Nuclepore filters and in suspended matter on the filters. The methods of inductively coupled plasma mass spectrometry and atomic absorption spectrophotometry were used. In contrast to most similar publications previously, the mean concentrations of elements weighted to water discharge (dissolved forms) and to suspended matter discharge (suspended forms) are obtained, which enables us to consider them as the closest to reality. Comparison with the mean concentrations in world rivers shows that the Corg and Fe concentrations in the water of the Northern Dvina River exceed them by 3-5 times. This is related to natural factors, primarily to specific features of the catchment basin (widely spread bogs). The presence or absence of correlation between trace elements and organoferric colloids significantly affects their concentration. The content of elements in the suspended matter of the river is similar to the mean global level, except for Corg and P. We calculate the discharges of dissolved and suspended elements for every year of research and the mean for the four-year period.