Microphytobenthos activity and fluxes at the sediment-water interface: interactions and spatial variability |
| |
Authors: | Marco Bartoli Daniele Nizzoli Pierluigi Viaroli |
| |
Institution: | (1) Dipartimento di Scienze Ambientali, Università degli Studi di Parma, 43100 Parma, Italy |
| |
Abstract: | In this study oxygen and nutrient fluxes and denitrification rates across the sediment-water interface were measured via intact core incubations with a twofold aim: show whether microphytobenthos activity affects these processes and analyse the dispersion of replicate measurements. Eighteen intact sediment cores (i.d. 8 cm) were randomly sampled from a shallow microtidal brackish pond at Tjarno, on the west coast of Sweden, and were incubated in light and in darkness simulating in situ conditions. During incubation O2, inorganic N and SiO2 fluxes and denitrification rates (isotope pairing) were measured. Assuming mean values of 18 cores as best estimate of true average (BEA), the accuracy of O2, NH4
+, NO3
- and SiO2 fluxes calculated for an increasing number of subsamples was tested. At the investigated site, microalgae strongly influenced benthic O2, inorganic N and SiO2 fluxes and coupled (Dn) and uncoupled (Dw) denitrification through their photosynthetic activity. In the shift between dark and light conditions NH4
+ and SiO2 effluxes (60 and 110 µmol m-2h-1) and Dn (5 µmol m-2 h-1) dropped to zero, NO3
- uptake (70 µmol m-2 h-1) showed a 30% increase, while Dw (20 µmol m-2 h-1) showed an 80% decrease. For O2 and NO3
- dark fluxes, 4 core replicates were sufficient to obtain averages within 5-10% of the best estimated mean, while 10-20% accuracy was obtained with 4-12 replicates for SiO2 and >10 replicates for NH4
+ dark fluxes. Mean accuracy was considerably lower for all light incubations, probably due to the patchy distribution of the benthic microalgal community. |
| |
Keywords: | Benthic diatoms Core incubation Denitrification Inorganic N and Si fluxes at the interface Spatial variability |
本文献已被 SpringerLink 等数据库收录! |
|