Nutrient variations in the Sava River Basin

• Published in: Journal of soils and sediments Vol. 15; no. 12; pp. 2380 - 2386
• Main Authors: Vrzel, Janja, Ogrinc, Nives
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01-12-2015; Springer Nature B.V
• Subjects: Agricultural land; Analysis; Annual; Anthropogenic factors; autumn; Earth and Environmental Science; Environment; Environmental Physics; Eutrophication; Freshwater; human population; Human populations; IASWS 2014: The Interactions Between Sediments and Water; Intensive farming; Land use; Locations (working); Low flow; nitrates; Nitrogen; Nutrient loading; Nutrients; phosphates; Phosphorus; pollution load; Population density; Regressions; River banks; River basins; River flow; Rivers; Seasonal variation; Seasonal variations; Sediments; soil; Soil Science & Conservation; Spatial analysis; summer; Temporal variations; Trend analysis; Trends; Water quality; watersheds; winter; Serbia; Slovenia; Croatia; Sava River; Croatia, Sava R; MED, Slovenia; Croatia, Lika, Srb; Nutrients; Sava River Basin; Computational methods; Statistics
• ISSN: 1439-0108; 1614-7480
• DOI: 10.1007/s11368-015-1190-7

PURPOSE: The first comprehensive evaluation and trend analysis of long-term nitrogen (N) and phosphorus (P) data was performed for the Sava River Basin (SRB) at locations in Slovenia, Croatia, and Serbia. MATERIALS AND METHODS: Data on long-term water quality at eight selected locations were evaluated statistically based on the period of reporting, availability of flow data, and the experience from our previous investigations. Trends in NO₃ ⁻ and PO₄ ³⁻ concentrations at locations were identified using simple linear regressions on log-transformed data. RESULTS AND DISCUSSION: Analysis indicated spatial and seasonal variability between locations. The highest long-term annual mean NO₃ ⁻ and PO₄ ³⁻ concentrations were observed in Croatia and Serbia at locations that are susceptible to anthropogenic nutrient loading arising from high human population densities and intensive agricultural land use. Temporal variations indicate that river flow plays an important role in the distribution of NO₃ ⁻ and PO₄ ³⁻ concentrations. Low flow during the summer months promotes reductive conditions leading to a minimum in annual mean NO₃ ⁻ concentrations and a maximum in annual mean PO₄ ³⁻ concentrations resulting from the release of inorganic P from sediments. The highest annual mean NO₃ ⁻ concentrations were observed in winter/autumn under higher flow conditions that leach NO₃ ⁻ from soil and banks into the river. The results of trend analysis show a reduction of nutrients at the majority of locations ranging from 8 to 58 %. CONCLUSIONS: Although trends in NO₃ ⁻ and PO₄ ³⁻ concentrations indicate a decrease at the majority of selected locations, it is still necessary to apply appropriate removal technologies in order to reduce the nutrient loads into the Sava River Basin and thereby improve water quality.