Use of GC and equilibrium calculations of CO 2 saturation index to indicate whether freshwater bodies in north-eastern Germany are net sources or sinks for atmospheric CO 2

Gelbrecht, Jörg; Fait, Martin; Dittrich, Maria; Steinberg, Christian

doi:10.1007/s002160050832

Cited by 45 publications

(45 citation statements)

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“…In our system, the dissolved pCO 2 was about 50% undersaturated compared to atmospheric concentrations, which is common for Lake Stechlin. 42 Thus, the existing gas bubbles would be similarly undersaturated with respect to atmospheric concentrations, resulting in an apparent CO 2 flux into the water. Each 1 mm diameter bubble at equilibrium would be undersaturated relative to atmospheric equilibrium by ∼ −4.2 × (Figure 4b).…”

Section: ■ Resultsmentioning

confidence: 99%

Enhancing Surface Methane Fluxes from an Oligotrophic Lake: Exploring the Microbubble Hypothesis

Mcginnis

Kirillin

Tang

et al. 2015

Environ. Sci. Technol.

100

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Exchange of the greenhouse gases carbon dioxide (CO2) and methane (CH4)across inland water surfaces is an important component of the terrestrial carbon (C) balance. We investigated the ﬂuxes of these two gases across the surface of oligotrophic Lake Stechlin using a ﬂoating chamber approach. The normalized gas transfer rate for CH4 (k600,CH4) was on average 2.5 times higher than that for CO2 (k600,CO2) and consequently higher than Fickian transport. Because of its low solubility relative to CO2, the enhanced CH4 ﬂux is possibly explained by the presence of microbubbles in the lake’s surface layer. These microbubbles may originate from atmospheric bubble entrainment or gas supersaturation (i.e., O2) or both. Irrespective of the source, we determined that an average of 145 L m−2 d−1 of gas is required to exit the surface layer via microbubbles to produce the observed elevated k600,CH4. As k600 values are used to estimate CH4 pathways in aquatic systems, the presence of microbubbles could alter the resulting CH4 and perhaps C balances. These microbubbles will also aﬀect the surface ﬂuxes of other sparingly soluble gases in inland waters, including O2 and N2

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Section: ■ Resultsmentioning

confidence: 99%

Enhancing Surface Methane Fluxes from an Oligotrophic Lake: Exploring the Microbubble Hypothesis

Mcginnis

Kirillin

Tang

et al. 2015

Environ. Sci. Technol.

100

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“…Wind speed data were recorded by ultrasound at lake-center monitoring stations every 10 min by a meteo multiprobe (ecoTech). The CO 2 concentration in surface waters (or partial pressure of CO 2 , P CO 2 ) was calculated from DIC concentrations, pH, and temperature, adjusting for the concentration of calcium ions (CaCO 0 3 , CaHCO z 3 , and CaOH + ), following Gelbrecht et al (1998). Conservative P CO 2 concentrations are calculated for each lake accounting for a possible measured pH bias of 0.2 from DOC effects (Herczeg et al 1985).…”

Section: Methodsmentioning

confidence: 99%

A feedback loop links brownification and anoxia in a temperate, shallow lake

Brothers¹,

Köhler²,

Attermeyer³

et al. 2014

Limnology & Oceanography

119

143

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This study examines a natural, rapid, fivefold increase in dissolved organic carbon (DOC) concentrations in a temperate shallow lake, describing the processes by which increased DOC resulted in anoxic conditions and altered existing carbon cycling pathways. High precipitation for two consecutive years led to rising water levels and the flooding of adjacent degraded peatlands. Leaching from the flooded soils provided an initial increase in DOC concentrations (from a 2010 mean of 12 6 1 mg L 21 to a maximum concentration of 53 mg L 21 by June 2012). Increasing water levels, DOC, and phytoplankton concentrations reduced light reaching the sediment surface, eliminating most benthic primary production and promoting anoxia in the hypolimnion. From January to June 2012 there was a sudden increase in total phosphorus (from 57 mg L 21 to 216 mg L 21 ), DOC (from 24.6 mg L 21 to 53 mg L 21 ), and iron (from 0.12 mg L 21 to 1.07 mg L 21 ) concentrations, without any further large fluxes in water levels. We suggest that anoxic conditions at the sediment surface and flooded soils produced a dramatic release of these chemicals that exacerbated brownification and eutrophication, creating anoxic conditions that persisted roughly 6 months below a water depth of 1 m and extended periodically to the water surface. This brownification-anoxia feedback loop resulted in a near-complete loss of macroinvertebrate and fish populations, and increased surface carbon dioxide (CO 2 ) emissions by an order of magnitude relative to previous years.

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“…Additionally, karst water is generally alkaline. The content of CO 2− 3 C in dissolved inorganic C is very small, so we did not need to consider it in the DIC calculation Gelbrecht et al, 1998). In this study, we used the formula F 1 below to calculate net carbon uptake by karst, using the estimates of mean annual [HCO3 − ], ion concentration during the dry-wet season, and the mean daily underground flow discharge.…”

Section: Determination Of Water Samples and Dic Methodsmentioning

confidence: 99%

Differences and influencing factors related to underground water carbon uptake by karsts in the Houzhai Basin, southwestern China

et al. 2016

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Abstract. Carbon sink in karstic areas is very important at a global scale. Consequently, accurate determination of the carbon sink of karst ecosystems has become a core issue in research. We used flow and carbon ion concentration data from three stations with different environmental background conditions in the Houzhai Basin, southwestern China, to analyse the differences in carbon uptake between stations and to determine their impact factors. The results show that carbon sink discharge was mainly controlled by the flow at each site. Preliminary analysis indicated that the rapid increase in flow only had a partial dilution effect on the ion concentrations due to the high speed and stability of chemical carbonate weathering. The Land-Use and Cover-Change (LUCC) type had important effects on the bicarbonate ion concentrations; under stable run-off conditions, the influence of flow variation on the ion concentration was lower than the effects of chemical carbonate weathering on bicarbonate ion concentrations under different environmental conditions (a comparison of Laoheitan and Liugu stations showed a difference of 150 %). However, if run-off increased significantly, the impact of run-off variation on bicarbonate ions was greater than the effects of chemical carbonate weathering caused under different environmental conditions. This work provides a reference for the calculation of the karst geological carbon sink.

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Use of GC and equilibrium calculations of CO 2 saturation index to indicate whether freshwater bodies in north-eastern Germany are net sources or sinks for atmospheric CO 2

Cited by 45 publications

References 1 publication

Enhancing Surface Methane Fluxes from an Oligotrophic Lake: Exploring the Microbubble Hypothesis

Enhancing Surface Methane Fluxes from an Oligotrophic Lake: Exploring the Microbubble Hypothesis

A feedback loop links brownification and anoxia in a temperate, shallow lake

Differences and influencing factors related to underground water carbon uptake by karsts in the Houzhai Basin, southwestern China

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