Earth-prints repository, logo   DSpace

About DSpace Software
|earth-prints home page | roma library | bologna library | catania library | milano library | napoli library | palermo library
Please use this identifier to cite or link to this item: http://hdl.handle.net/2122/8612

Authors: Rey, A.*
Etiope, G.*
Belelli-Marchesini, L.*
Papale, D.*
Valentini, R.*
Title: Geologic carbon sources may confound ecosystem carbon balance estimates: Evidence from a semiarid steppe in the southeast of Spain
Title of journal: Journal of geophysical research
Series/Report no.: / 117 (2012)
Issue Date: 27-Sep-2012
DOI: 10.1029/2012JG001991
Keywords: carbon dioxide
soil
ecosystems
Abstract: At a semiarid steppe site located in the SE of Spain, relatively large CO2 emissions were measured that could not be attributed to the ecosystem activity alone. Since the study site was located in a tectonically active area, it was hypothesized that a part of the measured CO2 was of geologic origin. This investigation included a survey of soil CO2 efflux, together with carbon isotope analyses of the CO2 in the soil atmosphere, soil CO2 efflux (i.e., Keeling plots), groundwater and local thermal springs. These measurements confirmed the hypothesis of degassing from geologic sources. In areas with local faults and ancient volcanic structures, soil CO2 efflux rates were significantly higher (i.e., up to 6.3 and 1.4 mmol CO2 m 2 s 1) than measurements in a comparable site that was some distance from fault sites (means of 1.0 and 0.43 mmol CO2 m 2 s 1 in March and June, respectively). The CO2 concentration in the soil atmosphere at the eddy covariance site reached 0.14% v/v at 0.70 m soil depth with a 13C-enriched isotopic composition (d13C from 10.2‰ to 16.6‰), consistent with the isotopic composition of the soil CO2 efflux estimated by Keeling plots (i.e., 16.6‰). 13C-enriched CO2 also occurred in local aquifers, and there was evidence of degassing from deep crust and mantle at regional scale by the helium isotopic ratio in spring waters located about 30 km (R/Ra: 0.12) and 200 km (R/Ra: 0.95) NW of the eddy covariance site. This study highlights the importance of considering CO2 sources of geologic origin when assessing the net ecosystem carbon balance of sites that may possibly be affected by circulation of such CO2-rich fluids.
Appears in Collections:04.04.12. Fluid Geochemistry
Papers Published / Papers in press

Files in This Item:

File SizeFormatVisibility
Rey et al 2012 - JGR.pdf480.67 kBAdobe PDFonly authorized users View/Open


Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.


Share this record
Del.icio.us

Citeulike

Connotea

Facebook

Stumble it!

reddit


 

Valid XHTML 1.0! ICT Support, development & maintenance are provided by CINECA. Powered on DSpace Software. CINECA