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High Primary Production Contrasts with Intense Carbon Emission in a Eutrophic Tropical Reservoir
- Source :
- Frontiers in Microbiology, 7, 1-13, Repositório Institucional da UFRN, Universidade Federal do Rio Grande do Norte (UFRN), instacron:UFRN, Frontiers in Microbiology 7 (2016) MAY, Frontiers in Microbiology, Frontiers in Microbiology, 7(MAY), Frontiers in Microbiology, 7, pp. 1-13
- Publication Year :
- 2016
- Publisher :
- Frontiers Media SA, 2016.
-
Abstract
- Recent studies from temperate lakes indicate that eutrophic systems tend to emit less carbon dioxide (Co-2) and bury more organic carbon (OC) than oligotrophic ones, rendering them CO2 sinks in some cases. However, the scarcity of data from tropical systems is critical for a complete understanding of the interplay between eutrophication and aquatic carbon (C) fluxes in warm waters. We test the hypothesis that a warm eutrophic system is a source of both CO2 and CH4 to the atmosphere, and that atmospheric emissions are larger than the burial of OC in sediments. This hypothesis was based on the following assumptions: (i) OC mineralization rates are high in warm water systems, so that water column CO2 production overrides the high C uptake by primary producers, and (ii) increasing trophic status creates favorable conditions for CH4 production. We measured water-air and sediment-water CO2 fluxes, CH4 diffusion, ebullition and oxidation, net ecosystem production (NEP) and sediment OC burial during the dry season in a eutrophic reservoir in the semiarid northeastern Brazil. The reservoir was stratified during daytime and mixed during nighttime. In spite of the high rates of primary production (4858 +/- 934 mg C m(-2) d(-1)), net heterotrophy was prevalent due to high ecosystem respiration (5209 +/- 992 mg C m(-2) d(-1)). Consequently, the reservoir was a source of atmospheric CO2 (518 +/- 182 mg C m(-2) d(-1)). In addition, the reservoir was a source of ebullitive (17 +/- 10 mg C m(-2) d(-1)) and diffusive CH4 (11 +/- 6 mg C m(-2) d(-1)). OC sedimentation was high (1162 mg C m(-2) d(-1)), but our results suggest that the majority of it is mineralized to CO2 (722 +/- 182 mg C m(-2) d(-1)) rather than buried as OC (440 mg C m(-2) d(-1)). Although temporally resolved data would render our findings more conclusive, our results suggest that despite being a primary production and OC burial hotspot, the tropical eutrophic system studied here was a stronger CO2 and CH4 source than a C sink, mainly because of high rates of OC mineralization in the water column and sediments.
- Subjects :
- 0106 biological sciences
Microbiology (medical)
Aquatic Ecology and Water Quality Management
010504 meteorology & atmospheric sciences
Carbon sequestration
01 natural sciences
Microbiology
Caatinga
chemistry.chemical_compound
Water column
Net ecosystem production
GeneralLiterature_REFERENCE(e.g.,dictionaries,encyclopedias,glossaries)
Semiarid
Original Research
0105 earth and related environmental sciences
semiarid
Total organic carbon
WIMEK
organic carbon burial
Organic carbon burial
Ecology
methane
010604 marine biology & hydrobiology
Aquatic Ecology
carbon dioxide
Carbon sink
Sediment
net ecosystem production
Aquatische Ecologie en Waterkwaliteitsbeheer
Mikrobiologi
Carbon dioxide
chemistry
Environmental chemistry
Environmental science
Ecosystem respiration
Eutrophication
Methane
Subjects
Details
- ISSN :
- 1664302X
- Volume :
- 7
- Database :
- OpenAIRE
- Journal :
- Frontiers in Microbiology
- Accession number :
- edsair.doi.dedup.....971daa815fdc86e7871b0a6ae477d27d