scholarly journals Characteristics of soil profile CO<sub>2</sub> concentrations in karst areas and their significance for global carbon cycles and climate change

2019 ◽  
Vol 10 (3) ◽  
pp. 525-538
Author(s):  
Qiao Chen
Keyword(s):  
Soil Ph ◽  
Soil Profile ◽  
Carbon Sink ◽  
Soil Depth ◽  
Global Climate ◽  
Co2 Concentration ◽  
Soil Co2 ◽  
Deep Soil ◽  
Carbon Cycles ◽  
Co2 Concentrations

Abstract. CO2 concentrations of 21 soil profiles were measured in Zhaotong City, Yunnan Province. The varying characteristics of soil profile CO2 concentrations are distinguishable between carbonate and noncarbonate areas. In noncarbonate areas, soil profile CO2 concentrations increase and show significant positive correlations with soil depth. In carbonate areas, however, deep-soil CO2 concentrations decrease and have no significant correlations with soil depth. Soil organic carbon is negatively correlated with soil CO2 concentrations in noncarbonate areas. In carbonate areas, such relationships are not clear. This means that the special geological process in carbonate areas – carbonate corrosion – absorbs part of the deep-soil-profile CO2. Isotope and soil pH data also support such a process. A mathematical model simulating soil profile CO2 concentration was proposed. In noncarbonate areas, the measured and the simulated values are almost equal, while the measured CO2 concentrations of deep soils are less than the simulated in carbonate areas. Such results also indicate the occurrence of carbonate corrosion and the consuming of deep-soil CO2 in carbonate areas. The decreased CO2 concentration was roughly evaluated based on stratigraphic unit and farming activities. Soil pH and the purity of CaCO3 in carbonate bedrock deeply affect the corrosion. The corrosion in carbonate areas decreases deep-soil CO2 greatly (accounting for 5.2 %–66.3 % with average of 36 %) and naturally affects the soil CO2 released into the atmosphere. Knowledge of this process is important for karst carbon cycles and global climate changes and it may be a part of the “missing carbon sink”.

scholarly journals Characteristics of soil profile CO<sub>2</sub> concentrations in karst areas and its significance for global carbon cycles and climate change

2019 ◽  
Author(s):  
Qiao Chen
Keyword(s):  
Soil Ph ◽  
Soil Profile ◽  
Soil Depth ◽  
Global Climate ◽  
Co2 Concentration ◽  
Soil Co2 ◽  
Deep Soil ◽  
Carbon Cycles ◽  
Global Climate Changes ◽  
Co2 Concentrations

Abstract. CO2 concentrations of 21 soil profiles were measured in Zhaotong City, Yunnan Province. The varying characteristics of soil profile CO2 concentration are distinguishable between carbonate and non-carbonate areas. In non-carbonate areas, soil profile CO2 concentrations increase and show significant positive correlations with soil depth. In carbonate areas, however, deep soil CO2 concentrations decrease and have no significant correlations with soil depth. Soil organic carbon is negatively correlated with soil CO2 concentrations in non-carbonate areas. In carbonate areas, such relationships are not clear. It means the special geological process in carbonate areas- carbonate corrosion- absorbs part of the deep soil profile CO2. Isotope and soil pH data also support such process. Mathematical model simulating soil profile CO2 concentration was proposed. In non-carbonate areas, the measured and the simulated values are almost equal, while the measured CO2 concentrations of deep soils are less than the simulated in carbonate areas. Such results also indicate the occurrence of carbonate corrosion and the consuming of deep soil CO2 in carbonate areas. The decreased CO2 concentration was roughly evaluated based on stratigraphic unit and farming activities. Soil pH and the purity of CaCO3 in carbonate bedrock deeply affect the corrosion. The corrosion in carbonate areas decreases deep soil CO2 greatly (accounting for 10–70 %, with average of 36 %), and naturally affects the soil CO2 released into the atmosphere. Knowledge of this process is important for karst carbon cycles and global climate changes, and it may be a potential part of the missing sink.

Differential effects of wetting and drying on soil CO2 concentration and flux in near-surface vs. deep soil layers

2020 ◽  
Vol 148 (3) ◽  
pp. 255-269 ◽  
Author(s):  
Kyungjin Min ◽  
Asmeret Asefaw Berhe ◽  
Chau Minh Khoi ◽  
Hella van Asperen ◽  
Jeroen Gillabel ◽  
...  
Keyword(s):  
Co2 Concentration ◽  
Soil Co2 ◽  
Deep Soil ◽  
Wetting And Drying ◽  
Near Surface ◽  
Soil Layers ◽  
Differential Effects ◽  
Soil Co2 Concentration

Effective remediation of diazinon from spent sheep dip wash by disposal on land

2007 ◽  
Vol 47 (1) ◽  
pp. 13 ◽  
Author(s):  
G. W. Levot
Keyword(s):  
Soil Profile ◽  
Soil Depth ◽  
Disposal Site ◽  
Deep Soil ◽  
Limit Of Quantification ◽  
Entire Volume ◽  
South Wales ◽  
Run Off ◽  
Australian Wool ◽  
Pre Treatment

Spent sheep dip wash (about 3500 L) containing 59 mg diazinon/L was evenly distributed onto a 450-m2 grassed, soil-bunded, sloping site near Cumnock in central New South Wales, Australia. The entire volume was contained within the bunded area but surface run-off created ponding in the lowest corner of the site. The mean concentration within the top 7 cm of soil was 2.32 mg/kg a day after application. By day 14, this had dropped to 0.4 mg/kg and by day 56, was below the limit of quantification (0.1 mg/kg). The half-life of diazinon in soil was estimated to be 7 days. Residues in the next 7 cm of soil depth were much lower and were below the limit of quantification in all samples collected at day 28 or later. This suggests that vertical leaching of diazinon within the soil profile did not occur despite more than 95 mm of rain during the trial interval. Throughout the 56-day trial interval, diazinon concentrations in the top 7 cm of soil 3 m downhill of the lowest corner of the dip disposal site were unchanged from background pre-treatment levels. No diazinon was detected in samples at 7–14 cm depth in the soil profile in this area. With neither vertical nor lateral movement of diazinon away from the initial treatment zone, we consider the disposal of spent diazinon sheep dips as described here, to be an acceptable and convenient option for Australian wool producers and dipping contractors. Suitable dip disposal sites should be situated away from sensitive locations in areas that have good grass cover over deep soil and that are contained by an effective bund. Stock and other animals should be excluded from these sensitive locations.

An experimental and modeling study of responses in ecosystems carbon exchanges to increasing CO2 concentrations using a tropical rainforest mesocosm

1998 ◽  
Vol 25 (5) ◽  
pp. 547 ◽  
Author(s):  
Guanghui Lin ◽  
Bruno D.V. Marino ◽  
Yongdan Wei ◽  
John Adams ◽  
Francesco Tubiello ◽  
...  
Keyword(s):  
Global Climate ◽  
Co2 Concentration ◽  
Atmospheric Co2 ◽  
Natural Ecosystems ◽  
Ecosystem Carbon ◽  
Co2 Concentrations ◽  
Net Ecosystem Carbon Exchange ◽  
Big Leaf Model ◽  
Atmospheric Co2 Concentrations ◽  
Change Response

The ecosystem carbon exchanges in the enclosed rainforest of Biosphere 2, an enclosed apparatus comprised of large synthetic ecosystems, were measured and modeled during the winter of 1995–1996 under different atmospheric CO2 concentrations. On eight separate days, this mesocosm was exposed to various levels of CO2 ranging from about 380 to 820 µmol mol-1 daily mean and then sealed 24 hours for continuous measurements of ecosystem CO2 fluxes. Our results indicated that net ecosystem carbon exchange in the mesocosm was enhanced by increasing CO2 over the short periods studied (2–7 weeks), but, as expected from physiological studies, the response is not linear. The main effect of short-term CO2 change was the enhancement of canopy CO 2 assimilation, while soil respiration was not affected by the atmospheric CO2 concentration. The whole ecosystem radiation use efficiency was significantly higher under higher CO2. The results of direct measurements were predicted well by a simple canopy model (the ‘big-leaf’ model) that incorporates current physiological understanding of the biochemistry of leaf photosynthesis. Validation of this model with a range of CO2 and light levels indicates that it can be used with confidence to predict the responses of natural ecosystems to global climate change. Response of ecosystem processes to elevated CO2 with relaxation time longer than a few weeks could not be resolved in this study, but longer-term closure experiments are planned to examine these processes.

scholarly journals Physiological and Transcriptome Responses to Elevated CO2 Concentration in Populus

Forests ◽  
2021 ◽  
Vol 12 (8) ◽  
pp. 980
Author(s):  
Tae-Lim Kim ◽  
Hoyong Chung ◽  
Karpagam Veerappan ◽  
Wi Young Lee ◽  
Danbe Park ◽  
...  
Keyword(s):  
Elevated Co2 ◽  
High Throughput Sequencing ◽  
Global Climate ◽  
Transcriptome Assembly ◽  
Soluble Sugar ◽  
Model Organism ◽  
Co2 Concentration ◽  
Total Soluble Sugar ◽  
Elevated Atmospheric Co2 ◽  
Co2 Concentrations

Global climate change is heavily affected by an increase in CO2. As one of several efforts to cope with this, research on poplar, a representative, fast growing, and model organism in plants, is actively underway. The effects of elevated atmospheric CO2 on the metabolism, growth, and transcriptome of poplar were investigated to predict productivity in an environment where CO2 concentrations are increasing. Poplar trees were grown at ambient (400 ppm) or elevated CO2 concentrations (1.4× ambient, 560 ppm, and 1.8× ambient, 720 ppm) for 16 weeks in open-top chambers (OTCs). We analyzed the differences in the transcriptomes of Populusalba × Populus glandulosa clone “Clivus” and Populus euramericana clone “I-476” using high-throughput sequencing techniques and elucidated the functions of the differentially expressed genes (DEGs) using various functional annotation methods. About 272,355 contigs and 207,063 unigenes were obtained from transcriptome assembly with the Trinity assembly package. Common DEGs were identified which were consistently regulated in both the elevated CO2 concentrations. In Clivus 29, common DEGs were found, and most of these correspond to cell wall proteins, especially hydroxyproline-rich glycoproteins (HRGP), or related to fatty acid metabolism. Concomitantly, in I-476, 25 were identified, and they were related to heat shock protein (HSP) chaperone family, photosynthesis, nitrogen metabolism, and carbon metabolism. In addition, carbohydrate contents, including starch and total soluble sugar, were significantly increased in response to elevated CO2. These data should be useful for future gene discovery, molecular studies, and tree improvement strategies for the upcoming increased-CO2 environments.

scholarly journals Kinetic Properties of Microbial Exoenzymes Vary With Soil Depth but Have Similar Temperature Sensitivities Through the Soil Profile

2021 ◽  
Vol 12 ◽  
Author(s):  
Ricardo J. Eloy Alves ◽  
Ileana A. Callejas ◽  
Gianna L. Marschmann ◽  
Maria Mooshammer ◽  
Hans W. Singh ◽  
...  
Keyword(s):  
Microbial Biomass ◽  
Temperature Sensitivity ◽  
Soil Profile ◽  
Current Knowledge ◽  
Soil Depth ◽  
Microbial Biomass C ◽  
Rate Theory ◽  
Kinetic Properties ◽  
Nutrient Inputs ◽  
Deep Soil

Current knowledge of the mechanisms driving soil organic matter (SOM) turnover and responses to warming is mainly limited to surface soils, although over 50% of global soil carbon is contained in subsoils. Deep soils have different physicochemical properties, nutrient inputs, and microbiomes, which may harbor distinct functional traits and lead to different SOM dynamics and temperature responses. We hypothesized that kinetic and thermal properties of soil exoenzymes, which mediate SOM depolymerization, vary with soil depth, reflecting microbial adaptation to distinct substrate and temperature regimes. We determined the Michaelis-Menten (MM) kinetics of three ubiquitous enzymes involved in carbon (C), nitrogen (N) and phosphorus (P) acquisition at six soil depths down to 90 cm at a temperate forest, and their temperature sensitivity based on Arrhenius/Q10 and Macromolecular Rate Theory (MMRT) models over six temperatures between 4–50°C. Maximal enzyme velocity (Vmax) decreased strongly with depth for all enzymes, both on a dry soil mass and a microbial biomass C basis, whereas their affinities increased, indicating adaptation to lower substrate availability. Surprisingly, microbial biomass-specific catalytic efficiencies also decreased with depth, except for the P-acquiring enzyme, indicating distinct nutrient demands at depth relative to microbial abundance. These results suggested that deep soil microbiomes encode enzymes with intrinsically lower turnover and/or produce less enzymes per cell, reflecting distinct life strategies. The relative kinetics between different enzymes also varied with depth, suggesting an increase in relative P demand with depth, or that phosphatases may be involved in C acquisition. Vmax and catalytic efficiency increased consistently with temperature for all enzymes, leading to overall higher SOM-decomposition potential, but enzyme temperature sensitivity was similar at all depths and between enzymes, based on both Arrhenius/Q10 and MMRT models. In a few cases, however, temperature affected differently the kinetic properties of distinct enzymes at discrete depths, suggesting that it may alter the relative depolymerization of different compounds. We show that soil exoenzyme kinetics may reflect intrinsic traits of microbiomes adapted to distinct soil depths, although their temperature sensitivity is remarkably uniform. These results improve our understanding of critical mechanisms underlying SOM dynamics and responses to changing temperatures through the soil profile.

Soil CO2 concentration and efflux from three forests in subtropical China

Soil Research ◽  
2012 ◽  
Vol 50 (4) ◽  
pp. 328 ◽  
Author(s):  
Lixia Zhou ◽  
Shenglei Fu ◽  
Mingmao Ding ◽  
Zhigang Yi ◽  
Weimin Yi
Keyword(s):  
Soil Depth ◽  
Soil Surface ◽  
Co2 Concentration ◽  
Soil Co2 Efflux ◽  
Co2 Efflux ◽  
Soil Co2 ◽  
Subtropical China ◽  
Mean Values ◽  
Soil Co2 Concentration ◽  
The Mean

Measurements of soil CO2 efflux and soil CO2 concentration concurrently are important for understanding the mechanism and regulation of CO2 in the soil. We have analysed CO2 concentration in a soil profile and soil CO2 efflux in three typical forests in subtropical China: monsoon evergreen broad-leaved forest (BF, 400 years old), pine and broad-leaved mixed forest (MF, 80 years old), and pine forest (PF, 70 years old). A portable soil CO2 sampler of simple sample operation was designed and used. The seasonal patterns of soil surface CO2 efflux and soil CO2 concentration were observed, and were positively correlated with rainfall, soil temperature, and moisture. The mean values of soil CO2 concentrations at the 15, 30, 45, and 60 cm soil depth were higher in BF (3368–9243 μL L–1) than in MF (1495–7662 μL L–1) and PF (1566–5730 μL L–1), while the mean values of soil surface CO2 efflux (Rsurface) were 0.55 ± 0.11 g m–2 h–1 in BF, 0.52 ± 0.10 g m–2 h–1 in MF, and 0.45 ± 0.07 g m–2 h–1 in PF. Soil CO2 concentration and Rsurface increased gradually with the age of the forests, but the incremental increase in soil CO2 concentration will be greater than that of Rsurface in MF and PF compared with BF. The data suggested that, although older forests have more C, younger forests probably will sequester C as CO2 faster than older forests.

scholarly journals Soil carbon sequestration by three perennial legume pastures is greater in deeper soil layers than in the surface soil

2016 ◽  
Vol 13 (2) ◽  
pp. 527-534 ◽  
Author(s):  
X.-K. Guan ◽  
N. C. Turner ◽  
L. Song ◽  
Y.-J. Gu ◽  
T.-C. Wang ◽  
...  
Keyword(s):  
Carbon Sequestration ◽  
Soil Carbon ◽  
Soil Profile ◽  
Soil Depth ◽  
Arable Land ◽  
Growth Period ◽  
Bare Soil ◽  
Soil Carbon Sequestration ◽  
Deep Soil ◽  
Perennial Legume

Abstract. Soil organic carbon (SOC) plays a vital role as both a sink for and source of atmospheric carbon. Revegetation of degraded arable land in China is expected to increase soil carbon sequestration, but the role of perennial legumes on soil carbon stocks in semiarid areas has not been quantified. In this study, we assessed the effect of alfalfa (Medicago sativa L.) and two locally adapted forage legumes, bush clover (Lespedeza davurica S.) and milk vetch (Astragalus adsurgens Pall.) on the SOC concentration and SOC stock accumulated annually over a 2 m soil profile. The results showed that the concentration of SOC in the bare soil decreased slightly over the 7 years, while 7 years of legume growth substantially increased the concentration of SOC over the 0–2.0 m soil depth. Over the 7-year growth period the SOC stocks increased by 24.1, 19.9 and 14.6 Mg C ha−1 under the alfalfa, bush clover and milk vetch stands, respectively, and decreased by 4.2 Mg C ha−1 in the bare soil. The sequestration of SOC in the 1–2 m depth of the soil accounted for 79, 68 and 74 % of the SOC sequestered in the 2 m deep soil profile under alfalfa, bush clover and milk vetch, respectively. Conversion of arable land to perennial legume pasture resulted in a significant increase in SOC, particularly at soil depths below 1 m.

scholarly journals Assessment of Soil Organic Carbon in Tropical Agroforests in the Churiya Range of Makawanpur, Nepal

2020 ◽  
Vol 2020 ◽  
pp. 1-5
Author(s):  
Lilu Kumari Magar ◽  
Gandhiv Kafle ◽  
Pradeep Aryal
Keyword(s):  
Climate Change ◽  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Soil Profile ◽  
Climate Change Mitigation ◽  
Soil Depth ◽  
Global Climate ◽  
Agroforestry Systems ◽  
Home Garden ◽  
Change Mitigation

This paper reports the findings of a research study conducted in three tropical agroforestry systems in the Makawanpur district of Nepal, to quantify the spatial and vertical distribution of soil organic carbon in 30 cm soil profile depth in agrisilviculture, home garden, and silvopasture. The three agroforestry systems represent tropical agroforests of Nepal. It was found that the soil had 24.91 t/ha soil organic carbon in 30 cm soil profile in 2018, with 2.1% soil organic matter concentration in average. Bulk density was found increasing with an increase in soil depth. The soil organic carbon was not found significantly different across different agroforestry systems. Looking into the values of stocks of soil organic carbon, it is concluded that the tropical agroforests have played a role in global climate change mitigation by storing considerable amounts of soil organic carbon and the storage capacity can further be increased. Involvement of farmers in the management of tropical agroforests cannot be ignored in the process of climate change mitigation.

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