Relationships between land use and nitrogen and phosphorus concentrations in Berze River basin [Latvia]
2021
Siksnane, I., Latvia Univ. of Life Sciences and Technologies, Jelgava (Latvia) | Lagzdins, A., Latvia Univ. of Life Sciences and Technologies, Jelgava (Latvia)
According to the latest HELCOM eutrophication assessment excessive inputs of nitrogen and phosphorus to the riverine and marine environments are one of the main reasons for water quality deterioration in the Baltic Sea. Both nitrogen and phosphorus are natural elements in terrestrial and aquatic ecosystems as essential for the plant growth. There are many factors both natural and anthropogenic that impact the amount of excess nutrients discharged in streams and rivers. This research examines how catchment area characteristics in terms of share of different land uses influence nutrient concentrations in water at a sub-basin level. Using the CORINE Land Cover 2018 data and results of Agricultural Runoff Monitoring Programme, as collected in the fifteen Berze River sub-basins during the time period of 2005–2020, the relationships between land use and concentrations of nitrate-nitrogen (NO3-N), ammonium-nitrogen (NH4-N), total nitrogen (TN), orthophosphate-phosphorus (PO4- P), and total phosphorus (TP) were assessed. In general, the results suggest that with increasing proportion of agricultural land in the catchment area the mean TN, NO3-N, TP, PO4-P concentrations in water are expected to increase. Contrary to agricultural land with increasing proportion of forest and semi-natural areas, the mean TN, NO3-N, TP, PO4-P concentrations in water decrease. With higher proportion of water bodies in the catchment area, the mean concentrations of NH4-N in water decrease as well. The conclusions of this study can be used to evaluate the current situation in the catchment areas where no water quality sampling and hydrology measurements are carried out, as well as for planning purposes of land use change in a given catchment area, which allows to forecast future changes in water quality.
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