scholarly journals Attributes of Atmospheric Carbon Monoxide Oxidation by Maine Forest Soils

1999 ◽  
Vol 65 (12) ◽  
pp. 5257-5264 ◽  
Author(s):  
G. M. King
Keyword(s):  
Co Oxidation ◽  
Forest Soils ◽  
Inhibitory Effect ◽  
Atmospheric Methane ◽  
Methyl Fluoride ◽  
Co Concentration ◽  
Net Uptake ◽  
Atmospheric Carbon Monoxide ◽  
Nitrite Inhibition ◽  
Water Contents

ABSTRACT CO, one of the most important trace gases, regulates tropospheric methane, hydroxyl radical, and ozone contents. Ten to 25% of the estimated global CO flux may be consumed by soils annually. Depth profiles for 14CO oxidation and CO concentration indicated that CO oxidation occurred primarily in surface soils and that photooxidation of soil organic matter did not necessarily contribute significantly to CO fluxes. Kinetic analyses revealed that the apparentKm was about 18 nM (17 ppm) and theV max was 6.9 μmol g (fresh weight)−1 h−1; the apparentKm was similar to the apparentKm for atmospheric methane consumption, but theV max was more than 100 times higher. Atmospheric CO oxidation responded sensitively to soil water regimes; decreases in water content in initially saturated soils resulted in increased uptake, and optimum uptake occurred at water contents of 30 to 60%. However, extended drying led to decreased uptake and net CO production. Rewetting could restore CO uptake, albeit with a pronounced hysteresis. The responses to changing temperatures indicated that the optimum temperature for net uptake was between 20 and 25°C and that there was a transition to net production at temperatures above 30°C. The responses to methyl fluoride and acetylene indicated that populations other than ammonia oxidizers and methanotrophs must be involved in forest soils. The response to acetylene was notable, since the strong initial inhibition was reversed after 12 h of incubation; in contrast, methyl fluoride did not have an inhibitory effect. Ammonium did not inhibit CO uptake; the level of nitrite inhibition was initially substantial, but nitrite inhibition was reversible over time. Nitrite inhibition appeared to occur through indirect effects based on abiological formation of NO.

scholarly journals Nitrogen addition decreases methane uptake caused by methanotroph and methanogen imbalances in a Moso bamboo forest

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Quan Li ◽  
Changhui Peng ◽  
Junbo Zhang ◽  
Yongfu Li ◽  
Xinzhang Song
Keyword(s):  
Community Structure ◽  
Forest Soils ◽  
Nitrogen Addition ◽  
N Deposition ◽  
Moso Bamboo ◽  
Bamboo Forest ◽  
N Addition ◽  
Atmospheric Methane ◽  
Key Factor ◽  
Moso Bamboo Forest

AbstractForest soils play an important role in controlling global warming by reducing atmospheric methane (CH4) concentrations. However, little attention has been paid to how nitrogen (N) deposition may alter microorganism communities that are related to the CH4 cycle or CH4 oxidation in subtropical forest soils. We investigated the effects of N addition (0, 30, 60, or 90 kg N ha−1 yr−1) on soil CH4 flux and methanotroph and methanogen abundance, diversity, and community structure in a Moso bamboo (Phyllostachys edulis) forest in subtropical China. N addition significantly increased methanogen abundance but reduced both methanotroph and methanogen diversity. Methanotroph and methanogen community structures under the N deposition treatments were significantly different from those of the control. In N deposition treatments, the relative abundance of Methanoculleus was significantly lower than that in the control. Soil pH was the key factor regulating the changes in methanotroph and methanogen diversity and community structure. The CH4 emission rate increased with N addition and was negatively correlated with both methanotroph and methanogen diversity but positively correlated with methanogen abundance. Overall, our results suggested that N deposition can suppress CH4 uptake by altering methanotroph and methanogen abundance, diversity, and community structure in subtropical Moso bamboo forest soils.

scholarly journals Soil, plant, and transport influences on methane in a subalpine forest under high ultraviolet irradiance

2009 ◽  
Vol 6 (7) ◽  
pp. 1311-1324 ◽  
Author(s):  
D. R. Bowling ◽  
J. B. Miller ◽  
M. E. Rhodes ◽  
S. P. Burns ◽  
R. K. Monson ◽  
...  
Keyword(s):  
High Elevation ◽  
Subalpine Forest ◽  
Atmospheric Methane ◽  
Vegetation Canopy ◽  
Conifer Forest ◽  
Uv Irradiance ◽  
Plant Foliage ◽  
Net Uptake ◽  
Scalar Similarity ◽  
Ultraviolet Irradiance

Abstract. Recent studies have demonstrated direct methane emission from plant foliage under aerobic conditions, particularly under high ultraviolet (UV) irradiance. We examined the potential importance of this phenomenon in a high-elevation conifer forest using micrometeorological techniques. Vertical profiles of methane and carbon dioxide in forest air were monitored every 2 h for 6 weeks in summer 2007. Day to day variability in above-canopy CH4 was high, with observed values in the range 1790 to 1910 nmol mol−1. High CH4 was correlated with high carbon monoxide and related to wind direction, consistent with pollutant transport from an urban area by a well-studied mountain-plain wind system. Soils were moderately dry during the study. Vertical gradients of CH4 were small but detectable day and night, both near the ground and within the vegetation canopy. Gradients near the ground were consistent with the forest soil being a net CH4 sink. Using scalar similarity with CO2, the magnitude of the summer soil CH4 sink was estimated at ~1.7 mg CH4 m−2 h−1, which is similar to other temperate forest upland soils. The high-elevation forest was naturally exposed to high UV irradiance under clear sky conditions, with observed peak UVB irradiance >2 W m−2. Gradients and means of CO2 within the canopy under daytime conditions showed net uptake of CO2 due to photosynthetic drawdown as expected. No evidence was found for a significant foliar CH4 source in the vegetation canopy, even under high UV conditions. While the possibility of a weak foliar source cannot be excluded given the observed soil sink, overall this subalpine forest was a net sink for atmospheric methane during the growing season.

The response to salinity of a population of Dactyloctenium aegyptium from a saline habitat in southern Nigeria

1994 ◽  
Vol 10 (2) ◽  
pp. 219-228 ◽  
Author(s):  
A. A. Adu ◽  
A. R. Yeo ◽  
O. T. Okusanya
Keyword(s):  
Sea Water ◽  
Nutrient Deficiency ◽  
Net Photosynthesis ◽  
Dry Weight ◽  
Potassium Nitrate ◽  
Inhibitory Effect ◽  
Ion Concentration ◽  
Dactyloctenium Aegyptium ◽  
Sodium And Potassium ◽  
Water Contents

ABSTRACTThe effects of salinity upon the growth, photosynthesis, ion and water contents of a population of Dactyloctenium aegyptium originating from a saline site in Nigeria were investigated. Growth was unaffected by a salinity of 10% artificial sea water, but was reduced by one third in 20% and by two thirds in 30% artificial sea water respectively. Initial adjustment to salinity was due both to increases in the concentrations of sodium and potassium per unit dry weight and to reduced hydration, the latter being the more important at higher salinities. The increase in ion concentration in the cell sap balanced the salinity of the medium at 10% artificial sea water, but was excessive at higher concentrations of sea water. Net photosynthesis was unaffected by 10% artificial sea water but declined at higher salinities. The potassium content of the plants did not fall below 200–250 mM, and the sodium to potassium ratio did not exceed three, even at the highest salinities. Variation in the concentration of nutrients (potassium, nitrate and sulphate) in the medium in the presence of 25% artificial sea water had significant effects upon growth, but these were small in relation to the inhibitory effect of the salinity.The reduction in growth could not be attributed to lack of osmotic adjustment or to nutrient deficiency, and was probably due to ion toxicity within the leaves. The tolerance to reduced hydration, combined with the ability to germinate in saline conditions previously observed, could enable D. aegyptium to establish in a saline soil. The population did not exhibit any halophytic characteristics but did survive with a low growth rate at salinities up to 50% artificial sea water. It is concluded that the species was able to colonize the saline site because of its inherent adaptability, rather than the possession of an ecotype adapted to saline conditions.

Physicochemical and biological factors affecting atmospheric methane oxidation in gray forest soils

Microbiology ◽  
2005 ◽  
Vol 74 (2) ◽  
pp. 216-220 ◽  
Author(s):  
I. K. Kravchenko ◽  
V. M. Semenov ◽  
T. V. Kuznetsova ◽  
S. A. Bykova ◽  
L. E. Dulov ◽  
...  
Keyword(s):  
Methane Oxidation ◽  
Forest Soils ◽  
Atmospheric Methane ◽  
Biological Factors ◽  
Factors Affecting ◽  
Gray Forest Soils

scholarly journals Declines in methane uptake in forest soils

2018 ◽  
Vol 115 (34) ◽  
pp. 8587-8590 ◽  
Author(s):  
Xiangyin Ni ◽  
Peter M. Groffman
Keyword(s):  
New Hampshire ◽  
Forest Soils ◽  
Global Environmental Change ◽  
Ecological Research ◽  
Atmospheric Methane ◽  
Northeastern United States ◽  
Global Environmental ◽  
Methane Uptake ◽  
Long Term Ecological Research

Forest soils are a sink for atmospheric methane (CH4) and play an important role in modulating the global CH4 budget. However, whether CH4 uptake by forest soils is affected by global environmental change is unknown. We measured soil to atmosphere net CH4 fluxes in temperate forests at two long-term ecological research sites in the northeastern United States from the late 1990s to the mid-2010s. We found that annual soil CH4 uptake decreased by 62% and 53% in urban and rural forests in Baltimore, Maryland and by 74% and 89% in calcium-fertilized and reference forests at Hubbard Brook, New Hampshire over this period. This decrease occurred despite marked declines in nitrogen deposition and increases in atmospheric CH4 concentration and temperature, which should lead to increases in CH4 uptake. This decrease in soil CH4 uptake appears to be driven by increases in precipitation and soil hydrological flux. Furthermore, an analysis of CH4 uptake around the globe showed that CH4 uptake in forest soils has decreased by an average of 77% from 1988 to 2015, particularly in forests located from 0 to 60 °N latitude where precipitation has been increasing. We conclude that the soil CH4 sink may be declining and overestimated in several regions across the globe.

A Simplified One-Dimensional Mathematical Model to Study the Transient Thermal Behavior of an Oxidation Catalyst with Both Low and High Levels of CO Concentration at the Inlet

2019 ◽  
Vol 14 (3) ◽  
Author(s):  
Priyabrata Mohapatra ◽  
Mayank Mittal
Keyword(s):  
Thermal Behavior ◽  
Co Oxidation ◽  
Heat Generation ◽  
Catalyst System ◽  
Oxidation Catalyst ◽  
Dual Fuel ◽  
Engine Exhaust ◽  
Warm Up ◽  
Co Concentration ◽  
Transient Thermal

Abstract In recent years, the permissible limits of engine exhaust emissions are reduced considerably. Hence a quick warm-up and high conversion efficiency of the catalyst system is essential to meet upcoming stringent emission regulations. In the present work, the transient thermal behavior of an oxidation catalyst is studied using a one-dimension mathematical modeling approach with the focus on CO oxidation for dual-fuel engine application. At first, the heat generation due to chemical reactions is considered negligible for studying the warm-up behavior. Upon obtaining a good agreement between predicted warm-up temperature profiles with available literature data, the effect of an electrical heater on the warm-up behavior is investigated. The model is then extended by incorporating heat generation due to CO oxidation. A simplified reaction rate model is considered in order to reduce the computational complexity. It is observed that the simplified model agrees well with the experimental data for both low and high levels of CO concentration at the inlet, typical in dual-fuel technology when an engine is operated under diesel and dual-fuel modes, respectively.

Methane uptake by various forest soils with and without litter

2020 ◽  
Author(s):  
Anna Walkiewicz ◽  
Piotr Bulak ◽  
Bruce Osborne ◽  
Mohammad Ibrahim Khalil ◽  
Syed Faiz-ul Islam ◽  
...  
Keyword(s):  
Forest Soils ◽  
Field Experiments ◽  
Deciduous Forest ◽  
Coniferous Forest ◽  
Mixed Forest ◽  
Ghg Emissions ◽  
Atmospheric Methane ◽  
Litter Layer ◽  
Negative Effect ◽  
Dry Conditions

<p>Forest soils are often a sink for atmospheric methane (CH<sub>4</sub>) and are thus worth special attention in the context of mitigation of greenhouse gases (GHGs) and offset of agricultural GHG emissions at farm to national levels. The litter layer influences the exchange of GHGs between soil and atmosphere; however, most studies focus on the contribution of only soil to the CH<sub>4</sub> cycle. In order to improve the inventory of this gas, it is worth investigating how litter influences the exchange of GHGs. Its effect on CH<sub>4</sub> uptake may vary in deciduous and coniferous sites due to the different properties of litter. Field experiments were carried out to assess the CH<sub>4</sub> uptake capability in 5 different soil types (with and without litter) under different forest types (deciduous, coniferous, and mixed) in Poland. During summer 2019, the highest CH<sub>4</sub> uptake (about 2 mg C m<sup>-2</sup> day<sup>-1</sup>) in a variant without litter on the ground was detected in Dystric Cambisol (with the highest C/N ratio) under a 100-year-old coniferous forest and in Albic Luvisol under a 58-year-old mixed forest. The presence of the litter level reduced the CH<sub>4</sub> flux in the range of 6-27% in these locations. Methane consumption was the lowest in silty soils (~ 0.4 – 1 mg C m<sup>-2</sup> day<sup>-1</sup>) in the mixed forest and decreased by 13-29% when covered with the litter layer. The negative effect of the litter layer on CH<sub>4</sub> absorption was the lowest (~ 3-4%) in sandy Eutric Gleysol under a 75-year-old deciduous forest with 90% of oak and 10% of European hornbeam. The dry conditions in the summer 2019 (with total rainfall 163 mm during the tested months in the studied region) resulted in low moisture in both the litter and soil. However, even low-humidity litter (below 10%) reduced CH<sub>4</sub> consumption rates in the measured sites.</p><p>Research was partially conducted under the project financed by Polish National Centre for Research and Development within of ERA-NET CO-FUND ERA-GAS Programme (ERA-GAS/I/GHG-MANAGE/01/2018).</p>

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