A new automated setup for stable isotope analysis of dissolved organic carbon

Bouillon, Steven; Korntheuer, Michael; Baeyens, Willy; Dehairs, Frank

doi:10.4319/lom.2006.4.216

Cited by 44 publications

(61 citation statements)

References 27 publications

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“…4c). Differences in the origin of particulate and dissolved organic carbon have previously been documented (Bouillon et al, 2006), but rarely as pronounced as shown here. More importantly, our study provides clear mechanisms explaining these strong variations (summarized in Sect.…”

Section: Origin and Exchange Of Organic Mattermentioning

confidence: 67%

“…Samples for DOC and δ 13 C DOC were obtained by pre-filtering surface water on pre-combusted Whatman GF/F filters, followed by filtration on 0.2 µm cellulose acetate syringe filters (Sartorius), and preserved by addition of 50 µL of H 3 PO 4 . DOC concentrations and δ 13 C signatures were measured with a modified Thermo HiperTOC TOC-analyzer, interfaced with a Thermo delta +XL IRMS as described by Bouillon et al (2006).…”

Section: Methodsmentioning

confidence: 99%

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Importance of intertidal sediment processes and porewater exchange on the water column biogeochemistry in a pristine mangrove creek (Ras Dege, Tanzania)

et al. 2007

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Abstract. We sampled a tidal creek (Ras Dege, Tanzania) during a 24-h cycle to document the variations in a suite of creek water column characteristics and to determine the relative influence of tidal and biological driving forces. Since the creek has no upstream freshwater inputs, highest salinity was observed at low tide, due to evaporation effects and porewater seepage. Total suspended matter (TSM) and particulate organic carbon (POC) showed distinct maxima at periods of highest water flow, indicating that erosion of surface sediments and/or resuspension of bottom sediments were an important source of particulate material. Dissolved organic carbon (DOC), in contrast, varied in phase with water height and was highest at low tide. Stable isotope data of POC and DOC displayed large variations in both pools, and similarly followed the variations in water height. Although the variation of δ 13 C DOC (−23.8 to −13.8‰) was higher than that of δ 13 C POC (−26.2 to −20.5‰), due to the different endmember pool sizes, the δ 13 C signatures of both pools differed only slightly at low tide, but up to 9‰ at high tide. Thus, at low tide both DOC and POC originated from mangrove production. At high tide, however, the DOC pool had signatures consistent with a high contribution of seagrass-derived material, whereas the POC pool was dominated by marine phytoplankton. Daily variations in CH 4 , and partial pressure of CO 2 (pCO 2 ) were similarly governed by tidal influence and were up to 7-and 10-fold higher at low tide, which stresses the importance of exchange of porewater and diffusive fluxes to the water column. When assuming that the high dissolved Correspondence to: S. Bouillon (steven.bouillon@vub.ac.be) inorganic carbon (DIC) levels in the upper parts of the creek (i.e. at low tide) are due to inputs from mineralization, δ 13 C data on DIC indicate that the organic matter source for mineralization had a signature of −22.4‰. Hence, imported POC and DOC from the marine environment contributes strongly to overall mineralization within the mangrove system. Our data demonstrate how biogeochemical processes in the intertidal zone appear to be prominent drivers of element concentrations and isotope signatures in the water column, and how pathways of dissolved and particulate matter transport are fundamentally different.

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Section: Origin and Exchange Of Organic Mattermentioning

confidence: 67%

Section: Methodsmentioning

confidence: 99%

Importance of intertidal sediment processes and porewater exchange on the water column biogeochemistry in a pristine mangrove creek (Ras Dege, Tanzania)

et al. 2007

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“…DOC was analysed according either on a Thermo HiperTOC-isotope ratio mass spectrometer (IRMS) or with an Aurora1030 TOC analyser (OI Analytical) coupled to a Delta V Advantage IRMS, with a precision better than ±5% (ref. 35) (refs 37,38). The detection limits were 0.30 and 0.15 µmol l −1 for NH 4 + and NO 3 − , respectively.…”

Section: Methodsmentioning

confidence: 99%

Globally significant greenhouse-gas emissions from African inland waters

et al. 2015

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Carbon dioxide emissions to the atmosphere from inland waters-streams, rivers, lakes and reservoirs-are nearly equivalent to ocean and land sinks globally. Inland waters can be an important source of methane and nitrous oxide emissions as well, but emissions are poorly quantified, especially in Africa. Here we report dissolved carbon dioxide, methane and nitrous oxide concentrations from 12 rivers in sub-Saharan Africa, including seasonally resolved sampling at 39 sites, acquired between 2006 and 2014. Fluxes were calculated from published gas transfer velocities, and upscaled to the area of all sub-Saharan African rivers using available spatial data sets. Carbon dioxide-equivalent emissions from river channels alone were about 0.4 Pg carbon per year, equivalent to two-thirds of the overall net carbon land sink previously reported for Africa. Including emissions from wetlands of the Congo river increases the total carbon dioxide-equivalent greenhouse-gas emissions to about 0.9 Pg carbon per year, equivalent to about one quarter of the global ocean and terrestrial combined carbon sink. Riverine carbon dioxide and methane emissions increase with wetland extent and upland biomass. We therefore suggest that future changes in wetland and upland cover could strongly a ect greenhouse-gas emissions from African inland waters.C limate predictions necessitate a full and robust account of natural and anthropogenic greenhouse-gas (GHG) fluxes, especially for CO 2 (refs 1-3), CH 4 (ref. 4) and N 2 O (ref. 5), which together accounted for 94% of the anthropogenic global radiative forcing by well-mixed GHGs in 2011 relative to 1750 (ref. 6). Inland waters (streams, rivers, lakes and reservoirs) are increasingly recognized as important sources of GHGs to the atmosphere, with global CO 2 and CH 4 emissions estimated at 2.1 PgC yr −1 (ref.3) and 0.7 PgC yr −1 (CO 2 -equivalents; CO 2 e) (ref. 4) (1 Pg = 10 15 g), respectively. Considering that the oceanic and land carbon (C) sinks correspond to ∼1.5 and ∼2.0 PgC yr −1 (ref. 7), respectively, the GHG flux from inland waters is significant in the global C budget.In a recent global compilation of inland CO 2 data 3 , <20 data points (out of 6,708, that is, <0.3%) represented African inland waters (with the exception of South Africa, which has been densely sampled), even though they account for ∼12% of both global freshwater discharge 8 and riverine surface area 3 , and include some of the largest rivers and lakes in the world. Equally for the global CH 4 database, there is a strong under-representation of tropical inland waters, whereby a recent synthesis 4 resorted to extrapolating CH 4 fluxes from temperate rivers.The prevailing large uncertainty involved in GHG flux estimates for inland waters, essentially due to the paucity of available data, is coupled to a poor understanding of underlying processes, both of which preclude gauging of future fluxes in response to human pressures. In particular, there is a need to further understand the link between inland water GHG fluxes and ...

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“…Consequently, estuaries and proximal continental shelves typically sustain high biological productivity (Walsh et al, 1981;Wollast, 1993Wollast, , 1998Cai, 2003), which may draw down CO 2 . This phenomenon, however, may be more than counteracted by enhanced heterotrophic activity, supported by organic carbon input from rivers (Smith and Hollibaugh, 1993;Heip et al, 1995;Hedges and Keil, 1995;Hedges et al, 1997;Hansell and Carlson, 1998;Bouillon et al, 2006;Jiang et al, 2010). Additionally, direct inorganic carbon input from river water, submarine groundwater discharge and exchanges with tidal marshes and mangroves play an important role in increasing the pCO 2 of estuarine and shelf waters (Moran et al, 1991;Miller and Moran, 1997;Neal et al, 1998;Raymond and Bauer, 2001;Borges et al, , 2006Cai et al, 2003;Wang and Cai, 2004;Jahnke et al, 2005;Bouillon et al, 2008;Jiang et al, 2008aJiang et al, , 2010Chen et al, 2012).…”

Section: C-t a Chen Et Al: Air-sea Exchanges Of Co 2 In The Worldmentioning

confidence: 99%

Air–sea exchanges of CO<sub>2</sub> in the world's coastal seas

et al. 2013

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Abstract. The air-sea exchanges of CO 2 in the world's 165 estuaries and 87 continental shelves are evaluated. Generally and in all seasons, upper estuaries with salinities of less than two are strong sources of CO 2 (39 ± 56 mol C m −2 yr −1 , positive flux indicates that the water is losing CO 2 to the atmosphere); mid-estuaries with salinities of between 2 and 25 are moderate sources (17.5 ± 34 mol C m −2 yr −1 ) and lower estuaries with salinities of more than 25 are weak sources . Mixing with low-pCO 2 shelf waters, water temperature, residence time and the complexity of the biogeochemistry are major factors that govern the pCO 2 in estuaries, but wind speed, seldom discussed, is critical to controlling the air-water exchanges of CO 2 . The total annual release of CO 2 from the world's estuaries is now estimated to be 0.10 Pg C yr −1 , which is much lower than published values mainly because of the contribution of a considerable amount of heretofore unpublished or new data from Asia and the Arctic. The Asian data, although indicating high pCO 2 , are low in sea-to-air fluxes because of low wind speeds. Previously determined flux values rely heavily on data from Europe and North America, where pCO 2 is lower but wind speeds are much higher, such that the CO 2 fluxes are higher than in Asia. Newly emerged CO 2 flux data in the Arctic reveal that estuaries there mostly absorb rather than release CO 2 .Most continental shelves, and especially those at high latitude, are undersaturated in terms of CO 2 and absorb CO 2 from the atmosphere in all seasons. Shelves between 0 and 23.5 • S are on average a weak source and have a small flux per unit area of CO 2 to the atmosphere. Water temperature, the spreading of river plumes, upwelling, and biological production seem to be the main factors in determining pCO 2 in the shelves. Wind speed, again, is critical because at high latitudes, the winds tend to be strong. Since the surface water pCO 2 values are low, the air-to-sea fluxes are high in regions above 50 • N and below 50 • S. At low latitudes, the winds tend to be weak, so the sea-to-air CO 2 flux is small. Overall, the world's continental shelves absorb 0.4 Pg C yr −1 from the atmosphere.

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A new automated setup for stable isotope analysis of dissolved organic carbon

Cited by 44 publications

References 27 publications

Importance of intertidal sediment processes and porewater exchange on the water column biogeochemistry in a pristine mangrove creek (Ras Dege, Tanzania)

Importance of intertidal sediment processes and porewater exchange on the water column biogeochemistry in a pristine mangrove creek (Ras Dege, Tanzania)

Globally significant greenhouse-gas emissions from African inland waters

Air–sea exchanges of CO<sub>2</sub> in the world's coastal seas

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A new automated setup for stable isotope analysis of dissolved organic carbon

Cited by 44 publications

References 27 publications

Importance of intertidal sediment processes and porewater exchange on the water column biogeochemistry in a pristine mangrove creek (Ras Dege, Tanzania)

Importance of intertidal sediment processes and porewater exchange on the water column biogeochemistry in a pristine mangrove creek (Ras Dege, Tanzania)

Globally significant greenhouse-gas emissions from African inland waters

Air–sea exchanges of CO&lt;sub&gt;2&lt;/sub&gt; in the world's coastal seas

Contact Info

Product

Resources

About

Air–sea exchanges of CO<sub>2</sub> in the world's coastal seas