The purpose of this research was to study the generation, sink, and emission of greenhouse gases by soils on technogenic parent materials, created at different stages of the Moskva River floodplain development (1—construction and 2—landscaping of residential areas).
Materials and methods
Field surveys revealed the spatial trends of concentration and emission of the greenhouse gases in following groups of soils: Retisols (RT-ab-ct) and Fluvisols (FL-hu, FL-hi.gl) before land engineering preparation for the construction, Urbic Technosols Transportic (TC-ub-ar.tn and TC-ub-hu.tn) at stage 1 and Urbic Technosols Folic (TC-ub-fo) at stage 2. CO2 and CH4 concentration in soils and their emission were determined using subsurface soil air equilibration tubes and the closed chamber method, respectively. Bacterial methane generation rate (MGR) and methane oxidation rate (MOR) were measured by kinetic methods.
Results and discussion
In natural soils MOR is caused only by intra-aggregate methanogenesis. The imbalance of methane generation and oxidation was observed in FL-hi.gl. It caused CH4 accumulation in the profile (7.5 ppm) and its emission to the atmosphere (0.11 mg CH4 m?2 h?1). RT-ab-ct acted as the sink of atmospheric methane. CO2 emission was 265.1?±?24.0 and 151.9?±?37.2 mg CO2 m?2 h?1 from RT-ab-ct and FL-hi.gl, respectively. In Technosols CH4 concentration was predominantly low (median was 2.7, 2.9, and 3.0 ppm, in TC-ub-ar.tn, TC-ub-hu.tn, and TC-ub-fo, respectively), but due to the occurrence of peat sediments under technogenic material, it increased to 1–2%. Methane emission was not observed due to functioning of biogeochemical barriers with high MOR. In TC-ub-ar.tn and TC-ub-hu.tn, the barriers were formed at 60-cm depth. In TC-ub-fo, the system of barriers was formed in Folic and Technic horizons (at 10- and 60-cm depth). CO2 emission was 2 times lower from TC-ub-ar.tn and TC-ub-hu.tn and 1.5 times higher from TC-ub-fo than from natural soils.
Conclusions
Greenhouse gas generation, sink, and emission by natural soils and Technosols in floodplain were estimated. CO2 and CH4 content in Technosols varied depending on the properties of parent materials. Technosols at stage 1 did not emit CH4 due to formation of biogeochemical barriers—soil layers of high CH4 utilization rates. Urbic Technosols (Folic) at stage 2 performed as a source of significant CO2 emission.
The first inventory and zoning of the emission and sink of methane and carbon dioxide in the urban structure of greenhouse gases from soils and surface technogenic formations (STFs) (Technosols) on technogenic, recrementogenic, and natural sediments have been performed with consideration for the global warming potential under conditions of different formation rate of these gases, underflooding, and sealing. From gas geochemical criteria and anthropogenic pedogenesis features, the main sources of greenhouse gases, their intensity, and mass emission were revealed. The mass fractions of emissions from the sectors of waste and land use in the inventories of greenhouse gas emissions have been determined. New sources of gas emission have been revealed in the first sector, the emissions from which add tens of percent to the literature and state reports. In the second sector, emissions exceed the available data in 70 times. Estimation criteria based on the degree of manifestation and chemical composition of soil-geochemical anomalies and barrier capacities have been proposed. The sink of greenhouse gases from the atmosphere and the internal (latent) sink of methane in soils and STFs have been determined. Ecological functions of soils and STFs have been shown, and the share of latent methane sink has been calculated. The bacterial oxidation of methane in soils and STFs exceeds its emission to the atmosphere in almost hundred times. 相似文献
Methane consumption in constructions is driven by its intense biofiltration which differs by seasons according to the general specifics of the functioning of methanotrophs. Three stages of methane biofiltration were identified—adaptation, optimum, and stress. It was established that methane biofiltration in soil construction is 1.5–2.0 times higher than in soil-like constructions. The biofiltration process under intense methane inflow leads to filtrate acidity increase; the Eh value drops in the summer period in constructions and grows during the winter season; a significant increase in microbial community stability is observed. 相似文献
Eurasian Soil Science - The response of the microbial community (microbial biomass carbon (Cmic), basal respiration (BR), and functional diversity (FD)) of agrosoddy-podzolic soil (Albic Glossic... 相似文献
Background, aim, and scope Exploited gas fields and underground gasholders are specific sources of increasing methane concentration. Methane migrates
into the soils by diffusion and convection through natural and technogenic cracks in geological structures and influences
the function of the soils. Soil cover of gas-bearing area functions as a specific, bilateral, periodically penetrating, geomembrane.
Soils shield, transform, and differentiate migrating fluxes of technogenic-allochthonous methane, preventing its emission
to the atmosphere. Problems of methane’s emission are rather current at the present, as methane is the second in importance
after CO2 greenhouse gas, since its concentration in the atmosphere annually grows by approximately 1%. By global estimations, methane
emissions in the gas industry make about 8% of annual receipt to the atmosphere, equal on the average to 500 Тg per a year
(Cicerone and Oremland, Global Biogeochem Cy 2:299–327, 1988). But these calculations are based on the account of the technological losses making 3–12% from the mining of natural gas.
The contribution of migratory methane fluxes to the atmosphere, as a rule, is not considered. The need for research of soil
cover functioning on gas-bearing areas is explained by the fact that processes of methane oxidation, its transformation in
soils, and emission to the atmosphere at these objects are now practically not being studied. The aim of our study was to
reveal specific processes of soil function and formation on gas-bearing areas by an example of underground gasholder.
Materials and methods The material was sampled in 1998–2003 at the territory of underground gasholder located in Albeluvisol’s zone in Russia. According
to the comparative-geographical method, 51 soil profiles have been studied in similar litologically geomorphological conditions
in various geochemical zones: in the industrial zone, in the zone of gas dissipation, and at the regional background. The
total square of investigated territory is about 60 km2. Six soil profiles were investigated in seasonal dynamics. Samples of soils for physical, chemical, and microbiological analyses
were taken from each horizon of soil profiles (202 samples). Samples of soil air for a definition of methane concentration
were taken from depths of 20, 40, and 60 cm. Methane emission to the atmosphere was measured near soil’s cuts and, in addition,
on all area of the investigated territory at knots of squares network through 700–1,000 m, in total at 32–42 points in May,
July, and November. Years of investigation have been split by technological and hydrothermal conditions. The periods with
the normal and lowered compression of gas in gasholder, dry and warm, and damp and cool years have been allocated. It has
influenced the soil function processes and considered an interpretation of the data received.
Results The changes of functional parameters of soils at a gas-bearing area influenced by methane fluxes migrating from gas deposits,
in comparison with background soils, are revealed. Such functional parameters are methane concentration in the soils, activity
of its bacterial oxidation, methane emission to the atmosphere, and oxidation–reduction potential. Spatial and temporary dynamics
of these parameters at gas-bearing and background territory are investigated.
Discussion Methane interaction with soil’s air is in its ascending (descending) and lateral diffusion and convection in soils. Methane
fluxes dissipate in porous space of soils forming gas anomalies. The technogenic-allochthonous methane concentration strongly
varies in soil’s air on gas-bearing area (1–10,500 ppm) and, on average, exceeds the autochthonous, microbiologically produced
methane at background territories. Migratory methane is deposited on diffusion and sorption barriers. The capacity of diffusion
barrier depends on effective coefficient of diffusion, the attitude of air and general porosity, and granulometric composition
and sharply differs in auto-, semi-hydro-, and hydromorphic soils reaching maximum in hydromorphicity and among the soils
with identical water content—in heavy soils. The capacity of the sorption barrier is defined by abiotic methane absorption
and a specific surface of soils and grows with their increasing intensity in soils to a heavier granulometric composition
or into soils with peat and gleyic horizons. The low sorption capacity leads to an increase of methane concentration in the
soil’s air and decreases its utilization by microorganisms, in which its quantity depends on sorption properties. The central
component of functioning that promotes a number of essential transformations in soils on gas-bearing areas is methane interaction
with the biotic phase. The periods of methane deposition by diffusion and sorption barriers are used for biological methane
oxidation and formation of biogeochemical barriers in soils. The activity of bacterial methane oxidation is characterized
by spatial variability and depends on the entrance of methane, defined by granulometric composition, soil moisture, the attitude
of air and general porosity, Eh, organic matter content, and salinization. During interaction between technogenic-allochthonous
methane and soil on diffusion, sorption, and biogeochemical barriers, its transformation occurs, accompanied by a strengthening
of variability of oxidation–reduction potential and formation of pedogenic, bacteriomorphic, and nanodispersic magnetic oxides
of iron.
Conclusions and perspectives Specificity of soil functioning on a gas-bearing area is in interaction of technogenic-allochtonous methane with solid, liquid,
gaseous, and living substance of the soil system. Spatial laws of soils functioning on gas-bearing area in the Albeluvisol’s
zone are revealed. Distinctions of soil functions depending on litologically geomorphological conditions are shown. The greatest
changes of parameters of functioning under the influence of technogenic-allochthonous methane occur in automorphic soils,
and it is less in semi-hydromorphic soils. Activity of bacterial methane oxidation in soils, emission, and consumption from
the atmosphere and their spatial laws are characterized by the time dynamics depending on hydrothermal and technological conditions
of seasons and years. During oxidation in soils of gas-bearing areas, carbon of methane is concentrated on a biogeochemical
barrier that is shown in the increase of methylotrophic microorganisms’ biomass and leads to a high variability and decrease
of Eh and to the formation of magnetic oxides of iron.
Recommendations Results of research can be used for carrying out ecological monitoring and an estimation of tightness of objects of the gas
industry. Activity of bacterial methane oxidation, Eh, and magnetic oxides of iron can be used as diagnostic parameters of
soils on gas-bearing areas.
This paper has been developed from a presentation at the conference SUITMA-4 (Soils in Urban, Industrial, Traffic, Mining
and Military Areas) Nanjing, China, 2007 相似文献