Ocena zawartości azotanów w wodach rzeki Dunajec

Abstract

Human activities transform the natural environment and cause an extreme biogen inflow to surface waters. The current investigation was aimed to estimate the effect of agricultural and domestic human activities at lowland area of the Dunajec watershed on water quality, both from the spatial and time perspective, which was assessed considering their nitrates content. Water was sampled during the vegetation periods 2003 and 2004 in one of the Dunajec River section flows through the rural areas between Zgłobice, above the industrial center in Tarnów and below Czchów dam reservoirs. Nitrates contents in the Dunajec waters depended both on the date and point of sampling and ranged between 0.38 and 4.84 mg NO3-N dm-3. In 2004 nitrates content on average was higher than in 2003 by 27%. The highest nitrates concentration was stated below Brzozowianka draining rural areas with poor sewage system. High nitrates concentrations were found at Zgłobice, a point closing typical of the agricultural section. The least nitrates content was found at Janowice below Pale nianka draining extensive farming areas. Markedly larger variations of nitrates content were observed in 2003 than in 2004. The highest nitrate concentrations were registered after intensive rainfall and top-dressing with nitrogen, wheras their lowest levels were found in the summer because of intensive development of vegetation. Water enrichment with nitrates in the agricultural area was observed at spring dates, but the reverse relation was noticed at other dates. Nitrates content fulfilled recommended values for A1 category of consumption water but most samples may be considered as sensitive to eutrophication because of nitrates concentration.