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Effects of Temperature and Water Saturation on CO_2 Production and Nitrogen Mineralization in Alpine Wetland Soils 被引量:14
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作者 GAO Jun-Qin OUYANG Hua +2 位作者 XU Xing-Liang ZHOU Cai-Ping ZHANG Feng 《Pedosphere》 SCIE CAS CSCD 2009年第1期71-77,共7页
Relationships between carbon (C) production and nitrogen (N) mineralization were investigated in two alpine wetland soils of the Tibetan Plateau using laboratory incubation under different temperatures (5, 15, 25, and... Relationships between carbon (C) production and nitrogen (N) mineralization were investigated in two alpine wetland soils of the Tibetan Plateau using laboratory incubation under different temperatures (5, 15, 25, and 35 ℃) and water saturation (noninundation and inundation). A significant positive relationship was found between CO2 production and N mineralization under increasing temperatures from 5 to 35 ℃ with the same water saturation condition in the marsh soil (r2 > 0.49, P < 0.0001) and the peat soil (r2 > 0.38, P < 0.002), and a negative relationship with water saturation increasing at the same temperature, especially 25 and 35 ℃, in the marsh soil (r2 > 0.70, P < 0.009) and the peat soil (r2 > 0.61, P < 0.013). In conclusion, temperatures and water saturation could regulate the relationship between CO2 production and net N mineralization in the Tibetan alpine marsh and peat soils. 展开更多
关键词 co2 production N mineralization TEMPERATURE water saturation WETLAND
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A Comparative Study on Chemical Composition of Supercritical CO_2 Extraction Products in Peels of Trichosanthes kirilowii Maxim. from Changqing District
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作者 于京平 李佳 +1 位作者 张永清 范英才 《Agricultural Science & Technology》 CAS 2013年第2期257-261,共5页
[Objective] This study aimed to investigate the differences in chemical composition of supercritical CO2 extraction products in peels of Trichosanthes kirilowii Maxim. from Changqing district. [Method] Supercritical f... [Objective] This study aimed to investigate the differences in chemical composition of supercritical CO2 extraction products in peels of Trichosanthes kirilowii Maxim. from Changqing district. [Method] Supercritical fluidextraction (SFE) and GCMS method were applied to determine and analyze the chemical components of the extracts in peels of three strains of Trichosanthes kirilowii Maxim. [Result] The chemical components of supercritical CO2 extraction products in peels of three strains of Trichosanthes kirilowii Maxim. varied., and the number of chemical components with normalized percentage content higher than 1% was 5, 7 and 8, respectively. There are 14 kinds of common components, and the relative content of hexadecanoic acid was the highest. [Conclusion] Supercritical CO2 extracts in peels of different strains of Trichosanthes kirilowii Maxim. contain different chemical components, providing scientific basis for breeding excellent varieties and the development and utilization of Trichosanthes kirilowii Maxim. 展开更多
关键词 Trichosanthes kirilowii Maxim. PEEL Supercritical co2 extraction products Chemical components coMPARISON
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Temperature Sensitivity of Soil Respiration Probed by Numerical Analysis of Field-Observed Data Sets
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作者 Ippei Iiyama 《Journal of Geoscience and Environment Protection》 2023年第8期65-84,共34页
Temperature sensitivity of soil respiration is essential to predict possible changes in terrestrial carbon budget on various scenarios about atmospheric and soil climates. Although it is often evaluated by using respi... Temperature sensitivity of soil respiration is essential to predict possible changes in terrestrial carbon budget on various scenarios about atmospheric and soil climates. Although it is often evaluated by using respiratory quotient “Q<sub>10</sub>”, Q<sub>10</sub> values of soil respiration seem to vary depending on methods or scales of evaluation. Aiming at probing how Q<sub>10</sub> values of soil respiration are evaluated differently for a field, this study used a model of soil respiration rate, and numerically evaluated soil respiration rates along depth by fitting the model to depth distributions of CO<sub>2</sub> concentration measured in a field. And temperature sensitivity of soil respiration rate was evaluated by comparing the determined soil respiration rates with atmospheric and soil temperatures measured in the field. The results showed that the relation between surface CO<sub>2</sub> emission rates and atmospheric temperatures was represented by lower Q<sub>10</sub> values than that between soil respiration rates and soil temperatures, presumably because the top soil layers had acclimatized in more extent to the existing thermal regime than the underlying deeper layers. Thus, for evaluating effects of long-term rise in atmospheric temperature on soil respiration, it is necessary to precisely predict the long-term change in depth distribution of soil temperature as well as to quantify temperature sensitivity of soil respiration along depth. The evaluated sensitivity of surface CO<sub>2</sub> emission rate to atmospheric temperature showed hysteresis, implying the needs for more knowledge about temperature sensitivity of soil respiration evaluated in both warming and cooling processes for better understandings and predictions about terrestrial carbon cycling. 展开更多
关键词 Air-Filled Porosity Inverse Analysis Mass Balance Potentially Maximum co2 production Rate Soil Gas Diffusion Water content
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Direct Measurement of CO_2 Retention in Arable Soils with pH Above 6.5 During Barometric Process Separation Incubation
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作者 Hannah CONRADS Joachim INGWERSEN +1 位作者 JU Xiaotang Thilo STRECK 《Pedosphere》 SCIE CAS CSCD 2018年第5期726-738,共13页
The barometric process separation(BaPS)technique is a well-established incubation method to simultaneously measure gross nitrification and respiration rates in soil.Its application,however,is still critical in soils w... The barometric process separation(BaPS)technique is a well-established incubation method to simultaneously measure gross nitrification and respiration rates in soil.Its application,however,is still critical in soils with pH above 6.5.Here,a substantial part of microbial CO_2 production is retained in soil solution(CO_2,aq)due to shifts in the carbonate equilibrium.This may lead to substantial errors in gas balance calculation.Yet,utilization of the BaPS technique is only reliable if the critical term is adequately quantified.We present an easy,inexpensive,and direct method,the sterilization-CO_2-injection(SCI)method,to measure CO_2 retention during soil incubation.Sterilized soil was incubated in the BaPS system,and defined volumes of CO_2 were injected to stepwise increase CO_2partial pressure(p CO_2)inside the chamber and to analyse the physicochemical equilibration process.Five exemplary agricultural soils from Northeast China and Southwest Germany were used for method establishment,presenting pH values between 4.4 and 7.6 and carbonate contents between 0% and 3.9%.We observed that in soils with pH>6.5,70%–90% of the injected CO_2 was taken up by the soil until the equilibrium inside the chamber was re-established.As expected,in soils with low pH(<6.5),measured CO_2 retention was low.CO_2 retention patterns were sensitive to incubation temperature with tri-fold dissolution capacity at 5~?C compared to 25?C,but insensitive to variations in soil water content.The resulting soil-specific relationship between p CO_2 and CO_2,aq concentration allowed the quantification of CO_2,aq concentration as a function of headspace p CO_2. 展开更多
关键词 carbonate equilibrium co2 dissolution capacity co_2 partial pressure microbial co2 production soil pH sterilization-co2-injection method volume of headspace air volume of soil solution
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