Land use, geology and soil properties control nutrient concentrations in headwater streams

Nutrient losses from headwater catchments (<50 km2) cause eutrophication problems downstream. Catchment properties are strongly reflected in the levels of nutrient concentrations streams. Based on measurements total and dissolved nitrogen (TN, DN) phosphorus (TP, DP) 235 small streams, we showed that proportion arable land a catchment had strongest positive effect concentrations, with coefficient determination (R2) 0.54, 0.64, 0.45, 0.51 for TN, DN, TP, DP, respectively. In contrast, increased forest wetland led to lower The geological composition major influence soil properties. turn, certain properties, such as clay content aluminum (Al), an important binding agent P, influenced particulate P (PP) Consequently, by using link between geology water quality, areas potentially sensitive were identified classifying bedrock categories into three groups. Approximately 25% Swedish was sensitive. Sensitive found regions sedimentary higher fractions even when agricultural small, indicating background concentrations.