Langtransporterte tilførsler av næringssalter til Ytre Oslofjord 1996-2006

The mean winter/spring contributions of nitrate and phosphate from the German Bight to the coastal water (5 - 30 m) outside the Oslofjord during the period 1996-2006 were estimated to respectively 70 % and 40 %. In the Oslofjord (5-30 m), the mean contribution of German Bight Water in the same period was estimated to 60 % in the outer and 45 % in the inner part of the fjord. In the brackish upper layer (0-5m), the mean contribution of nitrate from the German Bight during the winter period (December-February) was estimated to about 30 %. In the summer period, from June to August, the supply of nitrate was dominated by local sources, about 80 % in the upper 5m and 50-75% between 5 and 30 m depth. After 1995 the transport of nitrate during winter/spring, mainly from the German Bight, was reduced by about 40 % (from 42 to 24 mmol/m3) and consequently the mean nitrate concentration (1996-2006) in the coastal water in the inner Skagerrak and in the Oslofjord (5 - 30m) was reduced with 25-30 %, and in the 0-5m layer with about 15 %