Microbial respiratory quotient during basal metabolism and after glucose amendment in soils and litter

Dilly, Oliver

doi:10.1016/s0038-0717(00)00123-1

Cited by 139 publications

(112 citation statements)

References 15 publications

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“…Low RQ values were reported for the incubation of acidic soils from Argentina (0.27-0.65; Aon et al, 2001) and from Germany (Dilly, 2001; < 0.5 for some soils). In the latter soils the RQ increased to ∼ 1.0 immediately after glucose addition and reached ∼ 1.3 with time.…”

Section: Relationships Between Co 2 and O 2 In Low-ph Soilsmentioning

confidence: 88%

Using O2 to study the relationships between soil CO2 efflux and soil respiration

et al. 2015

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Abstract. Soil respiration is the sum of respiration processes in the soil and is a major flux in the global carbon cycle. It is usually assumed that the CO 2 efflux is equal to the soil respiration rate. Here we challenge this assumption by combining measurements of CO 2 with high-precision measurements of O 2 . These measurements were conducted on different ecosystems and soil types and included measurements of air samples taken from the soil profile of three Mediterranean sites: a temperate forest and two alpine forests. Rootfree soils from the alpine sites were also incubated in the lab. We found that the ratio between the CO 2 efflux and the O 2 influx (defined as apparent respiratory quotient, ARQ) was in the range of 0.14 to 1.23 and considerably deviated from the value of 0.9 ± 0.1 expected from the elemental composition of average plants and soil organic matter. At the Mediterranean sites, these deviations are explained as a result of CO 2 dissolution in the soil water and transformation to bicarbonate ions in these high-pH soils, as well as by carbonate mineral dissolution and precipitation processes. Thus, a correct estimate of the short-term, chamber-based biological respiratory flux in such soils can only be made by dividing the measured soil CO 2 efflux by the average (efflux-weighted) soil profile ARQ. Applying this approach to a semiarid pine forest resulted in an estimated short-term biological respiration rate that is 3.8 times higher than the chamber-measured surface CO 2 . The ARQ values often observed in the more acidic soils were unexpectedly low (< 0.7). These values probably result from the oxidation of reduced iron, which has been formed previously during times of high soil moisture and local anaerobic conditions inside soil aggregates. The results reported here provide direct quantitative evidence of a large temporal decoupling between soil-gas exchange fluxes and biological soil respiration.

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Section: Relationships Between Co 2 and O 2 In Low-ph Soilsmentioning

confidence: 88%

Using O2 to study the relationships between soil CO2 efflux and soil respiration

et al. 2015

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“…Oxidation of average phytoplanktonic material (sensu Takahashi et al, 1985;Anderson, 1995;Hedges et al, 2002) implies a low theoretical RQ of 0.7, as plankton are constituted by reduced and oxygen-poor components such as lipids and proteins. Humic-rich colored dissolved organic carbon (DOC) of terrestrial origin, which globally dominates freshwater bacterial substrates (del Giorgio et al, 1997;Jansson et al, 2007;Karlsson et al, 2009), is completely oxidized at an RQ of ca 0.9 (Dilly, 2001). However, recent studies show that bacteria selectively utilize sub-pools of the bulk DOC (Berggren et al, 2007;Guillemette and del Giorgio, 2011).…”

Section: Introductionmentioning

confidence: 99%

Magnitude and regulation of bacterioplankton respiratory quotient across freshwater environmental gradients

2011

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Bacterioplankton respiration (BR) may represent the largest single sink of organic carbon in the biosphere and constitutes an important driver of atmospheric carbon dioxide (CO 2 ) emissions from freshwaters. Complete understanding of BR is precluded by the fact that most studies need to assume a respiratory quotient (RQ; mole of CO 2 produced per mole of O 2 consumed) to calculate rates of BR. Many studies have, without clear support, assumed a fixed RQ around 1. Here we present 72 direct measurements of bacterioplankton RQ that we carried out in epilimnetic samples of 52 freshwater sites in Qué bec (Canada), using O 2 and CO 2 optic sensors. The RQs tended to converge around 1.2, but showed large variability (s.d. ¼ 0.45) and significant correlations with major gradients of ecosystem-level, substrate-level and bacterial community-level characteristics. Experiments with natural bacterioplankton using different single substrates suggested that RQ is intimately linked to the elemental composition of the respired compounds. RQs were on average low in net autotrophic systems, where bacteria likely were utilizing mainly reduced substrates, whereas we found evidence that the dominance of highly oxidized substrates, for example, organic acids formed by photo-chemical processes, led to high RQ in the more heterotrophic systems. Further, we suggest that BR contributes to a substantially larger share of freshwater CO 2 emissions than presently believed based on the assumption that RQ is B1. Our study demonstrates that bacterioplankton RQ is not only a practical aspect of BR determination, but also a major ecosystem state variable that provides unique information about aquatic ecosystem functioning.

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“…To estimate patterns of carbon fluxes in relation to sediment granulometry, a conversion factor of 0.38 and respiratory coefficient of 0.85 (Dilly 2001) was used to convert the amounts of consumed oxygen (mg O 2 dm −3 h −1 ) into amounts of carbon processed during respiration (mg C dm −3 h −1 ) (after Lampert 1984). …”

Section: Methodsmentioning

confidence: 99%

Testing the influence of sediment granulometry on heterotrophic respiration with a new laboratory flow-through system

et al. 2016

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Purpose Increased sedimentation due to land use intensification is increasingly affecting carbon processing in streams and rivers around the globe. This study describes the design of a laboratory-scale flow-through incubation system as a tool for the rapid estimation of sediment respiration. The measurements were compared with those obtained using an in situ closed chamber respiration method. The influence of sediment size on respiration rates was also investigated. Materials and methods Measurements were conducted on a pre-alpine gravel-bed river sediment separated into the following grain size fractions: > 60 mm (14.3%), 60-5 mm (60.2%), 5-2 mm (13.7%), 2-0.063 mm (11.1%) and <0.063 mm (0.6%). Concurrently, in situ and laboratory measurements were carried out on a naturally heterogeneous sediment. In situ respiration was determined in closed chambers as O 2 consumption over time, while in the laboratory, respiration was determined using flow-through respiration chambers. Oxygen concentrations were measured using a fibre-optic oxygen meter positioned at the inflow and outflow from the chamber. Results and discussion The mean respiration rates within naturally mixed riverbed sediments were 1.27 ± 0.3 mg O 2 dm −3 h −1 (n = 4) and 0.77 ± 0.1 mg O 2 dm −3 h −1 (n = 3) for the flow-through chamber system and closed chamber system, respectively. Respiration rates were statistically significantly higher in the flow-through chamber system (t test, p < 0.05), indicating that closed chamber measurements underestimated the oxygen consumption within riverbed sediments. Sediment grain size was found to significantly affect respiration rates in both systems (ANOVA, p < 0.001) with the fine sediment fraction (particle size <0.063 mm) having the highest respiration rate (r flow-through = 51 ± 23 mg O 2 dm −3 h −1 ). The smallest fractions (2-0.063 and <0.063 mm), which represent approximately 12% of total sediment volume, contributed 60% of total respiration. Conclusions The study demonstrated that flow-through respiration chambers more accurately estimate the respiration rate within riverbed sediments than in situ closed chambers, since the former experiment imitates the natural conditions where continuous interstitial flow occurs in the sediments. We also demonstrated that fine sediments (<5 mm) substantially contribute to heterotrophic respiration in the studied gravel-bed river.

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Microbial respiratory quotient during basal metabolism and after glucose amendment in soils and litter

Cited by 139 publications

References 15 publications

Using O<sub>2</sub> to study the relationships between soil CO<sub>2</sub> efflux and soil respiration

Using O<sub>2</sub> to study the relationships between soil CO<sub>2</sub> efflux and soil respiration

Magnitude and regulation of bacterioplankton respiratory quotient across freshwater environmental gradients

Testing the influence of sediment granulometry on heterotrophic respiration with a new laboratory flow-through system

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Microbial respiratory quotient during basal metabolism and after glucose amendment in soils and litter

Cited by 139 publications

References 15 publications

Using O&lt;sub&gt;2&lt;/sub&gt; to study the relationships between soil CO&lt;sub&gt;2&lt;/sub&gt; efflux and soil respiration

Using O&lt;sub&gt;2&lt;/sub&gt; to study the relationships between soil CO&lt;sub&gt;2&lt;/sub&gt; efflux and soil respiration

Magnitude and regulation of bacterioplankton respiratory quotient across freshwater environmental gradients

Testing the influence of sediment granulometry on heterotrophic respiration with a new laboratory flow-through system

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Using O<sub>2</sub> to study the relationships between soil CO<sub>2</sub> efflux and soil respiration

Using O<sub>2</sub> to study the relationships between soil CO<sub>2</sub> efflux and soil respiration