Table 1. Catchment characteristics of the seven big rivers and the whole Baltic Sea. All 7 rivers: Loads in 2014 and trends in 1995−2014 The area specific TN and TP loads of the seven big rivers widely varied with a general tendency to increase from the sparsely populated areas in the north towards the densely populated areas in the south (Figure 3). The highest area specific nutrient loads were detected in the Vistula river basins (Table 2), but some of the Daugava and Nemunas rivers were characterized by equally high values of area specific TN loads (Figure 3), while the average specific load from the whole river basins were remarkably lower than in the Vistula. The area specific TP loads were the highest in the Vistula River basin, and the lowest area specific loads were reported for the relatively pristine Kemi River basin and the upstream sub-catchments of the Neva basin (Figure 3). Figure 3. Area specific loads kg km-2 (load/ area) of TN and TP from the catchments or sub-catchment of the seven big rivers (2014). 2. Area specific loads kg km-2 (load/area) and concentrations of TN and TP in 2014. Concentrations were calculated from annual load and flow values. Area-specific TN load Area-specific TP load TN concentration TP concentration River in kg/km2 in kg/km2 in µg/l in µg/l Göta 280 8.0 626 18 Kemi 111 5.1 363 17 Daugava 228 8.6 1750 66 Nemunas 333 12 2140 75 Oder 323 19 3090 177 Vistula 341 42 2130 262 Neva 182 9.0 634 31 Total annual nutrients loads by rivers highly depend on annual average precipitation in the river basin and consequently river flow. Therefore flow normalized values for total N and P loads are used for inter-annual comparison of loads and building long term trends. In 2014 the non-normalized TN load was 226,000 t and TP load 15,300 t In 2014 the big seven rivers’ proportion of the flow to the Baltic Sea was 41%, and the respective proportions of TP load was 46% and TN load 29% (Fig. 4). The River Neva contributed over 40% of the total flow of the seven big rivers, but the Vistula had the highest TN and TP loads.
Table 1. Catchment characteristics of the seven big rivers and the whole Baltic Sea. All 7 rivers: Loads in 2014 and trends in 1995−2014 The area specific TN and TP loads of the seven big rivers widely varied with a general tendency to increase from the sparsely populated areas in the north towards the densely populated areas in the south (Figure 3). The highest area specific nutrient loads were detected in the Vistula river basins (Table 2), but some of the Daugava and Nemunas rivers were characterized by equally high values of area specific TN loads (Figure 3), while the average specific load from the whole river basins were remarkably lower than in the Vistula. The area specific TP loads were the highest in the Vistula River basin, and the lowest area specific loads were reported for the relatively pristine Kemi River basin and the upstream sub-catchments of the Neva basin (Figure 3). Figure 3. Area specific loads kg km-2 (load/ area) of TN and TP from the catchments or sub-catchment of the seven big rivers (2014). 2. Area specific loads kg km-2 (load/area) and concentrations of TN and TP in 2014. Concentrations were calculated from annual load and flow values. River Area-specific TN load in kg/km2 Area-specific TP load in kg/km2 TN concentration in µg/l TP concentration in µg/l Göta 280 8.0 626 18 Kemi 111 5.1 363 17 Daugava 228 8.6 1750 66 Nemunas 333 12 2140 75 Oder 323 19 3090 177 Vistula 341 42 2130 262 Neva 182 9.0 634 31 Total annual nutrients loads by rivers highly depend on annual average precipitation in the river basin and consequently river flow. Therefore flow normalized values for total N and P loads are used for inter-annual comparison of loads and building long term trends. In 2014 the non-normalized TN load was 226,000 t and TP load 15,300 t In 2014 the big seven rivers’ proportion of the flow to the Baltic Sea was 41%, and the respective proportions of TP load was 46% and TN load 29% (Fig. 4). The River Neva contributed over 40% of the total flow of the seven big rivers, but the Vistula had the highest TN and TP loads.
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