Biogeninių medžiagų koncentracijos ir kiekio dinamika Pietryčių Lietuvos upėse minimalaus nuotėkio laikotarpiu

Abstract

The investigation of the hydrological and hydrochemical alteration in the rivers of the Southeast of Lithuania is presented in this article. After comparison of the dynamics of the mineral nitrogen during the vears of big, average and small abundance of water, there was made an oh sensation, that the concentration of the investigated substances in the river waters is decreasing while the yield is increasing. The concentration of the mineral nitrogen in the investigated river waters of the Southeast of Lithuania did not overdraw [] permissible norm except the river Salcia. where the concentration has altered from 2,709 to 6,913 mg/l. We have calculated the amount of the hollowed out mineral nitrogen from the Šventoji and the Strėva rivers referring to the samples taken by JTC (once a month) and our own samples (taken once in a three months) and we have received the difference of 14 %.