Zmiany stężeń fosforanów w wodach rolniczej zlewni rzeki Raszynki

Abstract

The paper presents results of the phosphate concentration of waters in the catchment area of the river Raszynka located in the municipalities of Lesznowola, Raszyn and Michałowice in the province of Mazowieckie. Water samples from the river and from the midfield drainage ditches were collected in the period from March to November 2014–2015. Phosphate concentration were determined by spectrophotometry with ammonium molybdate. It was shown that 87% of water samples from the Raszynka river exceeds the maximum range of phosphate concentration (≤ 0.30 PO4 -3·dm-3) for surface water, and the highest number was recorded in the interval of 0.51–1.00 PO4 -3·dm-3. A large proportion of arable land (84.7%) under field vegetables (20%) and potatoes (27.5%) – in the upper part of the river, favoured an excessive concentration of phosphates in the surface waters. Reducing the intensity of agricultural land use in the downstream section of the river to the extensive meadows favoured a decrease of phosphate concentration.