Urea as a nitrogen source for the phytoplankton in the Oslofjord

✍ Scribed by S. Kristiansen

• Publisher: Springer-Verlag
• Year: 1983
• Tongue: English
• Weight: 723 KB
• Volume: 74
• Category: Article
• ISSN: 0025-3162
• DOI: 10.1007/bf00394270

✦ Synopsis

Ambient concentrations of urea in the inner Oslofjjord, Norway, showed a pronounced yearly cycle in 1980, with values in the range 0.1 to 10.0ktg-atNl-1; this cycle resembled that of ammonia although urea concentrations were usually lower. The uptake of urea by phytoplankton was investigated using lSN. Urea was usually a less important N source than NH4 +, and accounted for 0 to 53% (mean 19%) of summed NH4++NOi-+urea uptake rates from April to October. Absolute as well as relative (specific) uptake rates of urea were higher in the summer (June-August) than at other times. Uptake of urea was inhibited by NH~ concentrations higher than 1 to 2 ktgat N 1-1. The summed NH4++NO~+ urea uptake rate was exponentially related to temperature.