Nitrogen uptake and the importance of internal nitrogen loading in Lake Balaton

Presing, M., Herodek, S., Preston, T. and Voros, L. (2001) Nitrogen uptake and the importance of internal nitrogen loading in Lake Balaton. Freshwater Biology, 46(1), pp. 125-139. (doi: 10.1046/j.1365-2427.2001.00622.x)

Abstract

1. The importance of various forms of nitrogen to the nitrogen supply of phytoplankton has been investigated in the mesotrophic eastern and eutrophic western basin of Lake Balaton.<br /> 2. Uptake rates of ammonium, urea, nitrate and carbon were measured simultaneously. The uptake rates were determined using N-15 and C-14 methodologies, and N-2-fixation was measured using the acetylene-reduction method. The light dependence of uptake was described with an exponential saturation equation and used to calculate surface-related (areal) daily uptake. <br /> 3. The contribution of ammonium, urea and nitrate to the daily nitrogen supply of phytoplankton varied between 11 and 80%, 17 and 73% and 1 and 15%, respectively. N- 2-fixation was negligible in the eastern basin and varied between 5 and 30% in the western region of the lake. The annual external nitrogen load was only 10% of that utilized by algae.<br /> 4. The predominant process supplying nitrogen to the phytoplankton in the lake is the rapid recycling of ammonium and urea in the water column, The importance of the internal nutrient loading is emphasized.

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Preston, Professor Tom
• Authors: Presing, M., Herodek, S., Preston, T., and Voros, L.
• Subjects: Q Science > QH Natural history > QH301 Biology
• College/School: College of Science and Engineering > Scottish Universities Environmental Research Centre
• Journal Name: Freshwater Biology
• Publisher: Blackwell Publishing
• ISSN: 0046-5070
• Copyright Holders: © Copyright Blackwell
• First Published: First published in Freshwater Biology 46(1):125-139
• Publisher Policy: Reproduced in accordance with the copyright policy of the publisher