The changes in nutrient amounts in the river Susve in 1960-2001

Abstract

The paper discusses changes in water quality and leached nutrient amounts in the mid-size river Susve (tributary of the Nevezis). In 1960-1965, mineral nitrogen and phosphate phosphorus concentrations contained in the Susve river water were 0.5 mg/l and 0.015 mg/l respectively; this is considered as background concentration. In 1992-1993, average nitrogen concentration increased 10 times, phosphorus concentration increased 2.7 times (5.2 and 0.04 mg/l respectively). Nutrient concentration shows decreasing tendency during the last years. Leached NP amounts depending on their concentration and river runoff were comparatively small within the study period (1992-2001): on the average there were leached 9.3 kg/ha of total nitrogen, 0.11 kg/ha of total phosphorus, 6.9 and 0.06 kg/ha of mineral nitrogen and phosphorus respectively. Leached NP amounts (10.2 and 0.7% respectively) is insignificant contribution into total pollution which occurs in the basin as a result of the whole agricultural activity.