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1.
The processes controlling the solid–solution partitioning of organic matter in soils are central to understanding carbon cycling in terrestrial ecosystems, yet are poorly understood at present. We studied the partitioning of soil organic matter between solid and solution in batch titrations of 12 soil samples from three European forests in a range of climates. We also examined the release of soil organic matter on repeated leaching. The partitioning was simulated using a model that pictures the pool of potentially mobile organic matter to consist of fractions of differing solubilities. Desorption of organic matter was then effected by an increase in the electrical charge of the organic molecules due to their chemical reactions with other soil components. The model could simulate the partitioning of organic matter in all the soils using two parameters describing the amounts of soil organic matter in each fraction. The release of organic matter on repeated leaching was reasonably well described. The model predicted that dissolved organic matter should have become more hydrophilic with depth in the soil, due to the retention of more hydrophobic components in the upper horizons. This accorded with observed compositions of the soil organic matter. The model also showed that at the ambient pH of the soils, only a small proportion of the potentially mobile organic matter (comprising fulvic acids and hydrophilic moieties) was involved in partitioning to the solution. 相似文献
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植物残体向土壤有机质转化过程及其稳定机制的研究进展 总被引：10，自引：1，他引：9
土壤有机质的数量和质量不仅是衡量土壤肥力状况的核心要素,其形成、转化及稳定过程还与全球气候变化密切相关。植物残体是土壤有机质的初始来源,但由于其腐解过程的复杂、多变性以及土壤有机质、微生物的高度异质性,植物残体向土壤有机质的转化和稳定机理尚不十分明确。本文介绍并讨论了近年来关于植物残体向土壤有机质转化相关研究的新发现,探讨了微生物源和植物源有机质对土壤有机质的贡献,概述了土壤有机质形成的微生物驱动机制,并综述了植物残体输入后土壤有机质稳定性的相关研究,最后对该研究领域未来的发展进行展望,以期能够为科学地提高土壤的固碳能力提供参考。 相似文献
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Jiajia Gao Robert Mikutta Boris Jansen Georg Guggenberger Cordula Vogel Karsten Kalbitz 《植物养料与土壤学杂志》2020,183(1):27-41
Association of organic matter (OM) with minerals is an important pathway in the formation of stable OM in soil. While the importance of mineral–organic associations (MOA) in regulating soil carbon cycling has been rigorously demonstrated by empirical evidence, knowledge about the molecular‐scale arrangement of OM at mineral surfaces is still lacking. Such knowledge is urgently needed to disentangle the mechanisms of long‐term storage of soil OM. Based on indirect observations regarding the formation, composition, and structure of MOA, a conceptual multilayer model was proposed by Kleber et al. in 2007 to foster debate and help elucidating the structure and reactivity of MOA. According to this model, the associated OM at mineral surfaces is discrete and self‐organized into a multilayer structure. In this review, we aim to collect and evaluate existing studies that used this model to explain biogeochemical processes at mineral–organic interfaces, and based on this, assess the applicability of the model. The multilayer model has seen extensive adoption within soil science and related fields. In general, existing studies either support the concept of a patchy distribution of adsorbed OM on mineral surfaces or advocate that OM can be coprecipitated with nanosized poorly crystalline minerals or hydrolysable metals. However, the evidence for the patchy distribution of adsorbed OM cannot support the multilayer model on its own. There is little consensus about the role of N‐rich OM in forming the contact zone according to the multilayer model but surface conditioning by different classes of organic compounds appears to be an essential factor for the overall adsorption of OM. Nevertheless, large uncertainty still remains with respect to multilayer‐like organization of MOA. By taking advantage of recent developments in surface analytical sciences and computational chemistry, a rigid experimental testing of the multilayer model at the molecular level is still required and awaits to be integrated into improved concepts of MOA formation and OM stabilization. 相似文献
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Ying Teng Zhihong Xu Yongming Luo Frédérique Reverchon 《Journal of Soils and Sediments》2012,12(3):411-419
Purpose
Global climate change (GCC), especially global warming, has affected the material cycling (e.g., carbon, nutrients, and organic chemicals) and the energy flows of terrestrial ecosystems. Persistent organic pollutants (POPs) were regarded as anthropogenic organic carbon (OC) source, and be coupled with the natural carbon (C) and nutrient biogeochemical cycling in ecosystems. The objective of this work was to review the current literature and explore potential coupling processes and mechanisms between POPs and biogeochemical cycles of C and nutrients in terrestrial ecosystems induced by global warming. 相似文献8.
稻田土壤碳循环是我国陆地生态系统碳循环的重要组成部分。促进稻田生态系统碳的固定及稳定对减缓全球气候变化起着不容忽视的作用。微生物主导的有机碳转化过程是土壤碳循环研究的核心,微生物同化代谢介导的细胞残体迭代积累在土壤有机碳长期截获和稳定过程中发挥重要作用。与旱地土壤相比,关于稻田土壤中微生物残体积累动态对外源有机物质如作物秸秆输入的响应及主要影响因子的认识还相对有限,对微生物通过同化作用参与土壤固碳的过程和机制尚缺乏系统认识。基于此,本文介绍了微生物残体对土壤有机碳库形成和积累的重要性及评价指标,重点探讨了秸秆还田对稻田土壤微生物残体积累动态以及外源秸秆碳形成细胞残体转化过程的影响,分析了影响微生物残体积累转化的主要气候因素和土壤因素,最后提出了未来应借助先进的光谱和高分辨率成像技术并结合同位素示踪对微生物残体的稳定性与机理开展更为深入的研究。 相似文献
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Degradation of humic substances by soil microorganisms — a review Humic substances which represent differently extractable fractions of the soil organic matter exert multifarious effects on soil as a site for plant growth and a part of terrestrial environments. Among them especially humic acids and fulvic acids are subject to degradation and/or transformation by soil microorganisms. Several authors demonstrated the participation of different species of fungi, actinomycetes and also of non-mycelial aerobic or anaerobic bacteria in those processes under laboratory conditions. Indications exist that humic substances irrespective of their structure undergo degradation on cell surfaces due to the activity of exoenzymes. In this respect microbial phenoloxidases play an extraordinarily important role. The degradation rate of humic substances can be followed by optical, gravimetric and chemoanalytical methods as well as using biochemical and microbiological procedures (CO2 release, microbial growth, biomass formation). An objective evaluation, however, can be hindered by the adsorption of humic substances on microbial biomass and sometimes also by formation of novel humic-like microbial metabolites. Therefore it is necessary to apply a multifactorial approach in the study of the degradation of humic substances which includes both quantitative and qualitative parameters. To better elucidate how these processes may occur under natural conditions, mixed populations of soil microorganisms should be predominantly involved in future studies. 相似文献
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Soil aggregation is a key ecosystem process that strongly affects soil structure. Soil structure is the three dimensional arrangement of primary particles, organic matter, soil aggregates and associated pores. As such, soil aggregation influences the organization of soil biodiversity and soil-borne biogeochemical processes. Saprobic fungi (SF) have promising but largely untapped potential to offer new perspectives and insights into mechanisms of soil aggregation. The study of SF permits identification of traits that may predict soil aggregation component processes: formation, stabilization and disintegration. The measurement of fungal key traits in experiments aimed at soil aggregation effects will generate data necessary for mechanistic understanding. When such efforts are combined with collecting such information across a range of systems in curated databases this can, by channeling efforts, lead to a step change in our understanding and modeling of organism-mediated soil aggregation mechanisms and changes in functional diversity due to global change. 相似文献
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A better understanding of the links between dissolved organic matter and biogeochemical processes in soil could help in evaluating global soil dynamics. To assess the effects of land cover and parental material on soil biogeochemistry, we studied 120 soil samples collected from various ecosystems in Burgundy, France. The potential solubility and aromaticity of dissolved organic matter was characterised by pressurised hot-water extraction of organic carbon (PH-WEOC). Soil physico-chemical characteristics (pH, texture, soil carbon and nitrogen) were measured, as was the δ13C signature both in soils and in PH-WEOC. We also determined bacterial and fungal abundance and the genetic structure of bacterial communities. Our results show that the potential solubility of soil organic carbon is correlated to carbon and clay content in the soil. The aromaticity of PH-WEOC and its δ13C signature reflect differences in the decomposition pathways of soil organic matter and in the production of water-extractable organic compounds, in relation to land cover. The genetic structure of bacterial communities is related to soil texture and pH, and to PH-WEOC, revealing that water-extractable organic matter is closely related to the dynamics of bacterial communities. This comprehensive study, at the regional scale, thus provides better definition of the relationships between water-extractable organic matter and soil biogeochemical properties. 相似文献
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Isabel Miralles Manuel Sánchez-Marañón Gonzalo Almendros 《Soil biology & biochemistry》2007,39(10):2459-2470
Total soil organic matter levels and humic acid formation processes in mountain calcimorphic soils from Sierra María-Los Vélez Natural Park (Almería, Southern Spain) were found to differ depending on soil use (pine and oak forests, and cleared areas either cultivated or affected by bush encroachment). Biogeochemical indicators such as the concentration of exchangeable cations, or the concentration of the different types of humic substances were neither influenced by the type of vegetation nor soil use. In fact, multidimensional scaling and multiple correlations suggest that soil carbon sequestration processes are controlled by small-scale topographical features and their impact on water holding capacity. From a qualitative viewpoint, there were two more or less defined sets of soils: one set consisted of soils with humic acids with marked aliphatic character, displayed intense 2920 cm−1 infrared band, and had low optical density. The resolution-enhanced infrared spectra suggested typical lignin patterns and well-defined amide bands, which point to a selective preservation of comparatively young organic matter. This situation contrasts with that in other set of soils with low C levels (<20 g kg−1) where humic acids with featureless infrared spectra showed high aromaticity and were associated with perylenequinonic chromophors of fungal origin: this is considered the consequence of overlapping biogeochemical mechanisms involving both microbial synthesis and condensation processes. The results from visible and infrared derivative spectroscopies suggest that the reliability of statistically assessing the biogeochemical performance of the different uses on the site studied in terms of the intensity of the prevailing humic acid formation mechanisms, i.e., accumulation of inherited macromolecular substances in the former set, vs. microbial synthesis including the condensation of precursors of low molecular weight substances in the latter. 相似文献
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Alpine ecosystems are quite sensitive to global climatic changes. Drawing from two sets of remote sensing data (1986 and 2000) and field investigations, the ecological index method was used to document ecosystem changes in the Yangtze and Yellow River source regions of central Qinghai–Tibet. Although crucial to understanding alpine ecosystem responses to global climatic changes, and in assessing the potential for their rehabilitation, the impact of such changes on alpine soil characteristics, including structure, composition, water retention, as well as chemical and nutrient contents, is poorly understood. Over a 15-year period (1986–2000), climatic changes led to considerable degradation of alpine meadows and steppes. In the meadows, the surface layers of the soil became coarser, bulk density, porosity and saturated hydraulic conductivity rose, while water-holding capacity decreased. In comparison, steppe soils showed little changes in soil physical properties. Degradation of alpine ecosystems led to large losses in soil available Fe, Mn and Zn. Important losses in soil organic matter (SOM) and total nitrogen (TN) occurred in badly degraded ecosystems. Climate warming in the Qinghai–Tibet Plateau, caused by the impact of greenhouse gas, has resulted in changes of cold alpine ecosystem such as the significant alteration of the soil C and N cycles. 相似文献
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Nitrogen controls, on the seasonal and inter-annual variability of net ecosystem productivity (NEP) in a western temperate conifer forest in British Columbia, Canada, were simulated by a coupled carbon and nitrogen (C&N) model. The model was developed by incorporating plant–soil nitrogen algorithms in the Carbon-Canadian Land Surface Scheme (C-CLASS). In the coupled C&N-CLASS, the maximum carboxylation rate of Rubisco (Vcmax) is determined non-linearly from the modelled leaf Rubisco-nitrogen, rather than being prescribed. Hence, variations in canopy assimilation and stomatal conductance are sensitive to leaf nitrogen status through the Rubisco enzyme. The plant–soil nitrogen cycle includes nitrogen pools from photosynthetic enzymes, leaves and roots, as well as organic and mineral reservoirs from soil, which are generated, exchanged, and lost by biological fixation, atmospheric deposition, fertilization, mineralization, nitrification, root uptake, denitrification, and leaching. Model output was compared with eddy covariance flux measurements made over a 5-year period (1998–2002). The model performed very well in simulating half-hourly and monthly mean NEP values for a range of environmental conditions observed during the 5 years. C&N-CLASS simulated NEP values were 274, 437, 354, 352 and 253 g C m−2 for 1998–2002, compared to observed NEP values of 269, 360, 381, 418 and 264 g C m−2, for the respective years. Compared to the default C-CLASS, the coupled C&N model showed improvements in simulating the seasonal and annual dynamics of carbon fluxes in this forest. The nitrogen transformation to soil organic forms, mineralization, plant nitrogen uptake and leaf Rubisco-nitrogen concentration patterns were strongly influenced by seasonal and annual temperature variations. In contrast, the impact of precipitation was insignificant on the overall forest nitrogen budget. The coupled C&N modelling framework will help to evaluate the impact of nitrogen cycle on terrestrial ecosystems and its feedbacks on Earth's climate system. 相似文献
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严重退化红壤植被恢复后有机质富集和团聚体稳定性 总被引：3，自引：0，他引：3
Three types of soils： an eroded barren soil under continuous fallow, an eroded soil transplanted with Lespedeza shrubs （Lespedeza bieolor）, and an eroded soil transplanted with camphor tree （Cinnaraomum camphora） were investigated to quantify organic matter pools and aggregates in reforested soils using physical fractionation techniques and to determine aggregate stability in relation to the enrichment of soil organic carbon （SOC）. Soil organic matter （SOM） was physically fractionalized into free particulate organic matter （fPOM）, occluded particulate organic matter （oPOM）, and mineralassociated organic matter （mOM）. The SOM was concentrated on the surface soil （0 5 cm）, with an average C sequestration rate of 20-25 g C m^-2 year^-1 over 14 years. As compared to the eroded barren land, organic C content of fPOM, oPOM, and mOM fractions of the soil under Lespedeza and under camphor tree increased 12-15, 45-54, and 3.1-3.5 times, respectively. A linear relationship was found between aggregate stability and organic C （r^2 = 0.45, P 〈 0.01）, oPOM （r^2 = 0.34, P 〈 0.05）, and roOM （r^2 = 0.46, P 〈 0.01） of aggregates. The enrichment of organic C improved aggregate stability of the soil under Lespedeza but not that under camphor tree. However, further research is needed on the physical and biological processes involved in the interaction of soil aggregation and SOC sequestration in ecosystem. 相似文献
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不同土地利用下黑土密度分组中碳、氮的分配变化 总被引：17，自引：1，他引：16
陆地生态系统植被覆盖会影响有机质在土壤及其各组分中的分布,是控制土壤有机质储量的重要因子。通过对黑土有机碳、氮含量的估算,阐明土地利用变化对土壤有机碳库及轻组、重组有机碳、氮含量和结合态腐殖质有机碳含量的影响以及有机碳、氮的消长变化。结果表明:(1)不同土地利用方式下土壤0～20cm土层总有机碳(TOC)、全氮(TN)含量存在显著差异(p<0.05),自然土壤被破坏或转为农田,土壤总有机碳和全氮含量会持续下降,但农田化肥和有机肥配施后,土壤总有机碳和全氮含量显著增加;草地经过20年的植被恢复,土壤总有机碳含量显著高于农田化肥和无肥处理,有机碳库储量显著提高;(2)游离态轻组(Free-LF)和重组(HF)有机碳和氮含量与土壤总有机碳和全氮呈显著或极显著正相关,闭蓄态轻组(Occluded-LF)有机碳和氮在土壤中呈随机分布;(3)游离态轻组的C/N比高于全土和其他组分,易受微生物作用而降解,是土壤不稳定碳库的主要成分;(4)松结态胡敏酸碳含量与土壤总有机碳显著相关(p<0.05),土壤肥力随着胡敏酸的增加而提高。农田有机培肥不但能够提高有机质含量和土壤质量,也能显著提高农田生态系统抵押大气CO2的能力。 相似文献
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Advanced spectroscopic, microscopic, and tomographic characterization techniques to study biogeochemical interfaces in soil 总被引：1，自引：0，他引：1
Thilo Rennert Kai U. Totsche Katja Heister Michael Kersten Jürgen Thieme 《Journal of Soils and Sediments》2012,12(1):3-23
Purpose
Biogeochemical interfaces, the 3D association of minerals, soil organic matter, and biota, are hotspots of soil processes because they exhibit strong biological, physical, and chemical gradients. Biogeochemical interfaces have thicknesses from nanometers to micrometers and separate bulk immobile phases from mobile liquid or gaseous phases. The aim of this contribution is to review advanced microscopic and spectroscopic characterization techniques that allow for spatially resolved analysis of composition and properties of biogeochemical interfaces or their visualization. 相似文献18.
Kai U. Totsche Thilo Rennert Martin H. Gerzabek Ingrid Kögel‐Knabner Kornelia Smalla Michael Spiteller Hans‐Jörg Vogel 《植物养料与土壤学杂志》2010,173(1):88-99
Soil, the “Earth's thin skin” serves as the delicate interface between the biosphere, hydrosphere, atmosphere, and lithosphere. It is a dynamic and hierarchically organized system of various organic and inorganic constituents and organisms, the spatial structure of which defines a large, complex, and heterogeneous interface. Biogeochemical processes at soil interfaces are fundamental for the overall soil development, and they are the primary driving force for key ecosystem functions such as plant productivity and water quality. Ultimately, these processes control the fate and transport of contaminants and nutrients into the vadose zone and as such their biogeochemical cycling. The definite objective in biogeochemical‐interface research is to gain a mechanistic understanding of the architecture of these biogeochemical interfaces in soils and of the complex interplay and interdependencies of the physical, chemical, and biological processes acting at and within these dynamic interfaces in soil. The major challenges are (1) to identify the factors controlling the architecture of biogeochemical interfaces, (2) to link the processes operative at the individual molecular and/or organism scale to the phenomena active at the aggregate scale in a mechanistic way, and (3) to explain the behavior of organic chemicals in soil within a general mechanistic framework. To put this in action, integration of soil physical, chemical, and biological disciplines is mandatory. Indispensably, it requires the adaption and development of characterization and probing techniques adapted from the neighboring fields of molecular biology, analytical and computational chemistry as well as materials and nano‐sciences. To shape this field of fundamental soil research, the German Research Foundation (DFG) has granted the Priority Program “Biogeochemical Interfaces in Soil”, in which 22 individual research projects are involved. 相似文献
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微生物残体在土壤中的积累转化过程与稳定机理研究进展 总被引：3，自引：0，他引：3
近年来,关于微生物残体在土壤有机质积累和转化过程中的作用越来越受到研究者的关注。土壤有机质中微生物残体的数量和组成比例变化与土壤有机质的形成、容量大小及周转特征密切相关。对目前土壤微生物残体研究方面的相关进展进行了梳理和总结,在明确土壤微生物残体的来源及其重要性的基础上,介绍了土壤微生物残体定量和转化的表征方法,阐述了微生物残体在土壤有机质积累转化过程中的作用及其主要影响因素,探讨了微生物残体在土壤中的稳定机制,提出了微生物通过同化代谢作用驱动细胞残体积累进而促进土壤有机质积累和稳定过程中亟待探讨的科学问题。期望为进一步探究陆地生态系统土壤有机质周转与微生物过程的相互作用机理提供一定的思考。 相似文献
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J.E. Barrett R.A. Virginia J. Aislabie J.G. Bockheim W.B. Lyons J.N. Nkem H. Steltzer M.D. Wallenstein 《Soil biology & biochemistry》2006,38(10):3019-3034
Terrestrial environments of Victoria Land, Antarctica are ideal systems to test hypotheses about the sensitivity of ecosystem processes to climate variability, and the relationships between soil biodiversity and ecosystem functioning because of their high sensitivity to climate change and their limited diversity. This region is also considered among the most pristine of ecosystems, and therefore may serve as an indicator for detecting the response of other ecosystems to global environmental change. Rates and controls over key ecosystem processes remain poorly documented over much of Victoria Land, but it is generally held that the distribution and functioning of soil communities are most limited by the availability of liquid water and organic carbon. Here we review examples of ecosystem processes from several sites in North and South Victoria Land and develop a regional synthesis accounting for variation in the availability of soil resources (i.e. liquid water, organic matter, inorganic nutrients). Variation in soil microclimate, organic matter, moisture and salinity encountered over gradients of coastal to interior sites, latitude, and soil chronosequences are the primary controls over the structure of soil communities and their functioning. Imbalanced stoichiometric nutrient ratios frequently encountered in Victoria Land ecosystems also contribute to limited distribution of soil biota, and where they occur these elemental imbalances indicate lower biological activity and little biotic control over bulk element ratios in soils. Priorities and future directions of Victoria Land soil and ecosystem research are also discussed. 相似文献