Conjunctive use of in situ gas sampling and chromatography with geospatial analysis to estimate greenhouse gas emissions of a large Amazonian hydroelectric reservoir

Isabel L de Sousa Brandão; Chris M Mannaerts; Isaque W de Sousa Brandão; Joaquim Carlos Barbosa Queiroz; Wouter Verhoef; Augusto C Fonseca Saraiva; Heronides A Dantas Filho

doi:10.1016/j.scitotenv.2018.08.403

Conjunctive use of in situ gas sampling and chromatography with geospatial analysis to estimate greenhouse gas emissions of a large Amazonian hydroelectric reservoir

Sci Total Environ. 2019 Feb 10;650(Pt 1):394-407. doi: 10.1016/j.scitotenv.2018.08.403. Epub 2018 Aug 29.

Authors

Isabel L de Sousa Brandão¹, Chris M Mannaerts², Isaque W de Sousa Brandão³, Joaquim Carlos Barbosa Queiroz⁴, Wouter Verhoef⁵, Augusto C Fonseca Saraiva⁶, Heronides A Dantas Filho⁷

Affiliations

¹ Department of Water Resources, Faculty of Geo-Information Science and Earth Observation, University of Twente, Enschede, NL 7500, AE, the Netherlands. Electronic address: i.l.desousabrandao@utwente.nl.
² Department of Water Resources, Faculty of Geo-Information Science and Earth Observation, University of Twente, Enschede, NL 7500, AE, the Netherlands. Electronic address: c.m.m.mannaerts@utwente.nl.
³ Faculty of Chemistry, Federal University of Pará, Belém 66075-110, Brazil. Electronic address: isaque@ufpa.br.
⁴ Geoscience Institute, Federal University of Pará, Belém 66075-110, Brazil. Electronic address: joaquim@ufpa.br.
⁵ Department of Water Resources, Faculty of Geo-Information Science and Earth Observation, University of Twente, Enschede, NL 7500, AE, the Netherlands. Electronic address: w.verhoef@utwente.nl.
⁶ Analytical Center Laboratory, Belém 66815-140, Brazil.
⁷ Faculty of Chemistry, Federal University of Pará, Belém 66075-110, Brazil. Electronic address: herondantas@ufpa.br.

PMID: 30199684
DOI: 10.1016/j.scitotenv.2018.08.403

Abstract

Hydroelectric power reservoirs are considered potential contributors to the greenhouse effect in the atmosphere through the emittance of methane and carbon dioxide. We combined in situ sampling and gas chromatography with geostatistical and remote sensing approaches to estimate greenhouse gas (GHG) emissions of a large hydropower reservoir. We used remote sensing data to estimate the water surface and geospatial interpolation to calculate total emissions as a function of reservoir surface area. The CH₄ and CO₂ gas concentrations were linearly correlated to sampling time, confirming the adequacy of the in situ sampling method to measure GHG diffusive fluxes from reservoir water surfaces. The combination of high purity (99.99%) ISO-norm gas standards with a gas chromatograph, enabled us to achieve low measurement detection limits of 0.16 and 0.60 μmol mol^-1, respectively, for CH₄ (using a flame ionization or FID detector) and CO₂ (using a thermal conductivity or TCD detector). Our results show that CO₂ emissions are significantly (an order of 5.10²-10³) higher than those of CH₄ in both the spatial and temporal domain for this reservoir. The total diffusive GHG emissions over a year (June 2011 to May 2012) of the Tucuruí hydropower reservoir being in operation, in units of tons of carbon, added up to 6.82 × 10³ for CH₄ and 1.19 × 10⁶ for CO₂. We show that in situ GHG sampling using small floating gas chambers and high precision gas chromatography can be combined with geospatial interpolation techniques and remote sensing data to obtain estimates of diffusive GHG emissions from large water bodies with fluctuating water surfaces such as hydropower reservoirs. We recommend that more measurements and observations on these emissions are pursued in order to support and better quantify the ongoing discussions on estimates and mitigation of GHG emissions from reservoirs in the Amazon region and elsewhere in the world.

Keywords: Amazon; Diffusive emissions; GHG fluxes; Spatial interpolation; Tucuruí.