Riverine nutrient inputs have shown a declining trend, despite large interannual differences. Since the mid-1980s, flow-normalised inputs have decreased steadily at a rate of 2-3% per year. Winter is suited best for trend analyses of nutrient concentrations because biological activity in this season is low. Levels of phosphate and dissolved inorganic nitrogen (DIN) decrease significantly in winter, both in the open German Bight and in the Wadden Sea. Nutrient concentrations in the German Bight and Wadden Sea in winter, normalised to salinity 30, correlate significantly with flow-normalised riverine loads. In 2006, phosphate levels normalised to salinity 30 reached 1.06 ± 0.05 ¿mol/L (32.8 ± 1.5¿g/L P) in the Wadden Sea and coastal waters, exceeding the elevated level of 0.6 ¿mol/L (18.6 ¿g/L P) set by BLMP for these waters. Concentrations of dissolved inorganic nitrogen normalised to salinity 30, at 44.7 ± 3.2 ¿mol/L (0.63 ± 0.05 mg/L N), in 2006 still were three times higher than the elevated levels of 11.14 ¿mol/L (0.15 to 0.20 mg/L N).
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