The effect of tidal range on the flushing of ammonium from intertidal sediments of the Tagus estuary,Portugal |
| |
| Institution: | 1. Instituto de Oceanografia da Faculdade de Ciências, Universidade de Lisboa, Campo Grande, 1700 Lisboa, Portugal;2. Instituto de Investigação das Pescas e do Mar, Av. Brasília, 1400 Lisboa, Portugal;1. Laboratory for Protistology and Aquatic Ecology, Department of Biology, Ghent University, Krijgslaan 281-S8, 9000 Gent, Belgium;2. Research Department, Botanic Garden Meise, Nieuwelaan 38, 1860 Meise, Belgium;1. Instituto Oceanográfico-Universidade de São Paulo (IO-USP), Praça do Oceanográfico 191, São Paulo, SP 05508-120, Brazil;2. Universidade Federal do Rio Grande, Departamento de Física, Campus Carreiros, CP 474, Rio Grande, RS 96201-900, Brazil;3. Escola Superior de Tecnologia, Universidade do Algarve, Campus da Penha, 8005-139 Faro, Portugal;1. Ecosystem Management Research Group (ECOBE), University of Antwerp, 2610 Wilrijk, Belgium;2. Royal Netherlands Institute for Sea Research (NIOZ), 4400 AC Yerseke, The Netherlands;3. StatUA Center for Statistics, University of Antwerp, 2000 Antwerp, Belgium;4. Department of Civil Engineering, Ghent University, 9052 Zwijnaarde, Belgium;1. Programa de Pós-graduação em Biodiversidade Vegetal, Instituto de Ciências de Biológicas, Universidade Federal de Goiás, Goiânia GO 74690-900, Brazil;2. Departamento de Botânica, Universidade Federal de Goiás, Goiânia GO 74690-900, Brazil;3. Programa de Pós-gradução em Ecologia e Evolução, Instituto de Ciências Biológicas, Universidade Federal de Goiás, Goiânia GO 74690-900, Brazil;4. Programa de Pós-graduação em Ciências Ambientais, Universidade de Brasília, Planaltina DF 73.340-710, Brazil;5. Programa de Pós-Graduação em Geociências Aplicadas, Universidade de Brasília, Instituto de Geociências, Brasília DF 70.910-900, Brazil;6. Universidade de Brasília, Laboratório de Geoquímica, Instituto de Geociências, Brasília DF 70.910-900, Brazil;7. Instituto de Pesquisas Hidráulicas, Universidade Federal do Rio Grande do Sul, Avenida Bento Gonçalves, Porto Alegre RS 91.501-970, Brazil;8. Joint International Laboratory LMI OCE ‘Observatory of Environmental Change’, UnB/IRD, Brasília DF 70.910-900, Brazil;9. Institut de Recherche pour le Développement, UMR Espace-DEV, Maison de la télédétection, 500 rue J.F. Breton, 34000 Montpellier, France |
| |
| Abstract: | The time-course evolution of ammonium concentration has been examined in the flood water during the first 25 min of tidal inundation. The way this transport fluctuates with the tidal ranges and wind conditions was investigated. Flood water was collected at three sites, located along a transect from the lower to the upper intertidal area of the Tagus estuary. At spring and intermediate tides, the periods of air exposure vary slightly along the transect due to the high tidal amplitude and the flatness of the area, but the upper site remains uncovered at neap tide over the entire tidal cycle. At each site, sampling was performed at different tidal ranges covering the neap-spring tidal cycle and wind conditions. Ammonium was determined in the flood water at short time intervals: 1, 2, 3, 4, 5, 10, 15, 20 and 25 min. A clear pattern was observed along the transect: considerable quantities of ammonium were exported from the sediment to the water column at the beginning of the inundation, ranging from 0.2 to 4.8 mmol m?2 d?1. The highest transport was recorded at the lower intertidal site under spring tide conditions, which corresponds to the higher energetic situation and shorter emersion period. The lowest transport was observed at the upper intertidal site during the first inundation that followed three days of neap tide and continuous exposure of the sediment to the air. The value rates (0.2–4.8 mmol m?2 d?1) were one order of magnitude higher than those calculated from molecular diffusion (0.07 – 0.16 mmol m?2 d?1). This study points to the importance of the tidal flushing of ammonium from the intertidal sediments, and its spatial and tidal fluctuation. |
| |
| Keywords: | |
| 本文献已被 ScienceDirect 等数据库收录！ |
|
