Kooperativer Bibliotheksverbund

Berlin Brandenburg

and
and

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
Language
Year
  • 1
    Language: English
    In: 한국토양비료학회 학술발표회 초록집, 2014, Vol.2014(6), pp.156-156
    Keywords: Methane ; Carbondioxide ; Eddy Covariance ; Fen ; Reed ; Ghg
    Source: DBpia - 디비피아 (Nurimedia)
    Source: DBpia (Nurimedia)
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 2
    Language: English
    In: Soil Biology and Biochemistry, December 2016, Vol.103, pp.349-364
    Description: The mechanistic integration of microbial behavior remains a major challenge in biogeochemical modeling of organic matter turnover in soil. We recently introduced dynamic feedbacks between specific microbial groups and their micro-environment in a biogeochemical model (Pagel et al., 2014). Here, the model was applied in a case study to simulate pesticide degradation coupled to carbon (C) turnover in the detritusphere. We aimed at unravelling the effects of litter-derived substrate supply on the spatiotemporal dynamics of the microbial community and the resulting biogeochemical processes at the mm-scale in soil. We linked genetic information on abundances of bacteria, fungi and specific pesticide degraders to the biogeochemical dynamics of C and a generic model compound (MCPA, 4-chloro-2-methylphenoxyacetic acid) in soil by multiobjective calibration. We observed and simulated increased dissolved organic and microbial C as well as accelerated MCPA degradation in soil up to a 6 mm distance to litter. We found that, whereas transport and sorption processes act as extrinsic control on the encounter of microorganisms and substrates, microbial traits such as substrate preference or metabolic capabilities intrinsically determine turnover rates triggering feedback effects on physicochemical processes such as diffusion. A process analysis revealed that C cycling and pesticide degradation in the detritusphere were strongly controlled by fungal dynamics. Our study demonstrates that integrating mathematical modeling with experiments provides comprehensive insight into the microbial regulation of matter cycling in soil.
    Keywords: Functional Trait ; Soil-Litter Interface ; Priming Effect ; Carbon Isotopes ; Functional Gene Tfda ; Pareto Analysis ; Agriculture ; Chemistry
    ISSN: 0038-0717
    E-ISSN: 1879-3428
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 3
    Language: English
    In: Soil Biology and Biochemistry, December 2018, Vol.127, pp.137-147
    Description: Complex interactions between biodegradation and mass transfer of organic compounds drive the fate of pesticides in soil ecosystems. We hypothesized that, at the small-scale, co-location of degraders and pollutants in soils may be a prerequisite for efficient biodegradation of these chemicals. In non-co-localized micro-environments, however, diffusive and advective solute transport as well as active transport of microbial degraders towards their corresponding substrate may improve the accessibility of microbial substrates. The objective of this study was to test whether water flow can accelerate microbial pesticide degradation by facilitating the encounter of spatially separated pesticides and bacterial degraders at the millimeter scale. Combining natural and sterilized soil aggregates, we built soil cores with different spatial localizations of the pesticide 2,4-dichlorophenoxyacetic acid (2,4-D) and microbial degraders: (i) homogeneous distribution of microorganisms and 2,4-D throughout the soil core, (ii) co-localized microorganisms and 2,4-D in a mm soil location, and iii) separated microorganisms and 2,4-D in two mm soil locations spaced 1 cm apart. Following the fate of C labelled 2,4-D (mineralization, extractable and non-extractable residues) as well as the abundance of bacterial 2,4-D degraders harboring the gene over an incubation period of 24 days, we observed decreased biodegradation of 2,4-D with increasing spatial separation between substrate and bacterial degraders. We found evidence that advection is a key process controlling the accessibility of 2,4-D and pesticide degraders. Advective solute transport induced leaching of about 50% of the initially applied 2,4-D regardless of initial spatial distribution patterns. Simultaneously, advective transport of 2,4-D and bacterial degraders triggered their re-encounter and compensated for the leaching-induced separation of initially co-localized microorganisms and 2,4-D. This resulted in effective biodegradation of 2,4-D, comparable to the homogeneous treatment. Similarly, advective transport processes brought substrate and degraders into contact if both were initially separated. Thus, advection more effectively removed bioaccessibility limitations to pesticide degradation than diffusive transport alone. These results emphasize the importance of considering spatial microbial ecology as well as biogeophysics at the mm scale to better understand the fate of pesticides at larger scales in soil.
    Keywords: Accessibility ; Biodegradation ; Mm Scale ; Biogenic and Abiotic Non Extractable Residues ; Advection and Diffusion Transport ; Tfda Genes ; Agriculture ; Chemistry
    ISSN: 0038-0717
    E-ISSN: 1879-3428
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 4
    Language: English
    In: Journal of Irrigation and Drainage Engineering, 2015, Vol.141(6), p.4014072(11)
    Description: Soil water plays a key role in crop growth and yield formation. A sustainable irrigation management depends on a reliable soil water monitoring. The present study was conducted to derive site-specific and pedotransfer calibrations for Aquaflex time domain transmission (TDT) soil water sensors and to test their performance under field conditions. In spring 2009, two soil moisture networks were installed in the Kraichgau region and in the Swabian Alb, southwest Germany. Each network consists of 21 stations, each equipped among others with an Aquaflex TDT sensor installed 15-cm-deep in the soil. At each station, soil samples were taken and analyzed for the gravimetric soil water content, bulk density, soil texture, electrical conductivity, pH, and organic nitrogen and carbon content. The factory calibration delivered highly biased soil water contents [~ -8.0 Volume (Vol.) %]. The root mean square errors (RMSEs) were high, reaching on average 8.3 and 12.6 Vol.% in Kraichgau and Swabian Alb, respectively. The RMSEs of pedotransfer calibrations declined to 3.7 Vol.% in Kraichgau and to 3.4 Vol.% in Swabian Alb. In both regions, the slope of the calibration curve was affected by soil bulk density. High-leverage independent variables affecting the intercept were electrical conductivity in Kraichgau and silt fraction in Swabian Alb. Site-specific calibrations performed best. On average, the RMSE in Kraichgau was 3.0 Vol.%, in Swabian Alb 1.9 Vol.%. The pedotransfer-based approach proposed in the present study is a good compromise between labour effort and accuracy for soil landscapes with similar texture and properties. DOI: 10.1061/(ASCE)IR.1943-4774.0000838. Author keywords: Time domain transmission technique; Kraichgau; Swabian Alb; Regional scale; Soil moisture network.
    Keywords: Probes (Electronic Instruments) – Maintenance and Repair ; Soil Moisture – Measurement ; Agricultural Land – Properties
    ISSN: 0733-9437
    E-ISSN: 19434774
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 5
    In: Pest Management Science, January 2014, Vol.70(1), pp.70-79
    Description: Byline: Nguyen La, Marc Lamers, Vien V Nguyen, Thilo Streck Keywords: pesticides; rice fields; fish ponds; modelling; water quality; south-east Asia; Vietnam Abstract Background In Vietnam, paddy rice fields have been identified as a major non-point source of pesticide pollution of surface- and groundwater which is often directly used for domestic purposes. One strategy to assess the risk of pesticide pollution is to use process-based models. Here, we present a new model developed for simulating short-term pesticide dynamics in combined paddy rice field-fish pond farming systems. The model was calibrated using the Gauss-Marquardt-Levenberg algorithm and validated against measured pesticide concentrations of a paddy field-fish pond system typical for northern Vietnam. Results In the calibration period, model efficiencies were 0.82 for dimethoate and 0.87 for fenitrothion. In the validation period, modelling efficiencies slightly decreased to 0.42 and 0.76 for dimethoate and fenitrothion, respectively. Scenario simulations revealed that a field closure period of 1day after pesticide application considerably reduces the risk of pond and surface water pollution. Conclusion These results indicate that the proposed model is an effective tool to assess and evaluate management strategies, such as extended field closure periods, aiming to reduce the loss of pesticides from paddy fields. [c] 2013 Society of Chemical Industry
    Keywords: Pesticides ; Rice Fields ; Fish Ponds ; Modelling ; Water Quality ; South‐East Asia ; Vietnam
    ISSN: 1526-498X
    E-ISSN: 1526-4998
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 6
    Language: English
    In: Biogeochemistry, 2014, Vol.117(1), pp.185-204
    Description: Microbiologically active biogeochemical interfaces are excellent systems to study soil functions such as pesticide degradation at the micro-scale. In particular, in the detritusphere pesticide degradation is accelerated by input of fresh organic carbon from litter into the adjacent soil. This observed priming effect suggests: (i) pesticide degradation is strongly coupled to carbon turnover, (ii) it is controlled by size and activity of the microbial community and (iii) sorption and transport of dissolved carbonaceous compounds and pesticides might regulate substrate availability and in turn decomposition processes. We present a new mechanistic 1D model ( PEsticide degradation Coupled to CArbon turnover in the Detritusphere, PECCAD ) which implements these hypotheses. The new model explicitly considers growth and activity of bacteria, fungi and specific pesticide degraders in response to substrate availability. Enhanced pesticide degradation due to availability of a second source of carbon (dissolved organic carbon) is implemented in the model structure via two mechanisms. First, additional substrate is utilized simultaneously with the pesticide by bacterial pesticide degraders resulting in an increase in their size and activity. Second, stimulation of fungal growth and activity by additional substrates leads directly to higher pesticide degradation via co-metabolism. Thus, PECCAD implicitly accounts for litter-stimulated production and activity of unspecific fungal enzymes responsible for co-metabolic pesticide degradation. With a global sensitivity analysis we identified high-leverage model parameters and input. In combination with appropriate experimental data, PECCAD can serve as a tool to elucidate regulation mechanisms of accelerated pesticide degradation in the detritusphere.
    Keywords: Soil organic matter ; Mechanistic model ; Biogeochemical interface ; Priming effect ; Carbon isotopes ; Gene abundance
    ISSN: 0168-2563
    E-ISSN: 1573-515X
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 7
    Language: English
    In: Soil Biology and Biochemistry, 2010, Vol.42(10), pp.1879-1887
    Description: Much is known about mechanisms and regulation of phenoxy acid herbicide degradation at the organism level, whereas the effects of environmental factors on the performance of the phenoxy acid degrading communities in soils are much less clear. In a microcosm experiment we investigated the small-scale effect of litter addition on the functioning of the MCPA degrading communities. C labelled MCPA was applied and the functional genes and were quantified to characterise bacterial MCPA degradation. We identify the transport of litter compounds as an important process that probably regulates the activity of the MCPA degrading community at the soil–litter interface. Two possible mechanisms can explain the increased abundance and MCPA degradation below the litter layer: 1) transport of α-ketoglutarate or its metabolic precursors reduces the costs for regenerating this co-substrate and thereby improves growth conditions for the MCPA degrading community; 2) external supply of energy and nutrients changes the internal resource allocation towards enzyme production and/or improves the activity of bacterial consortia involved in MCPA degradation. In addition, the presence of litter compounds might have induced fungal production of litter-decaying enzymes that are able to degrade MCPA as well.
    Keywords: Mcpa ; Degradation ; Detritusphere ; Tfda ; Tfdaα ; Regulation ; Transport ; Α-Ketoglutarate ; Agriculture ; Chemistry
    ISSN: 0038-0717
    E-ISSN: 1879-3428
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 8
    Language: English
    In: Soil biology & biochemistry, 2010, Vol.42, pp.1879-1887
    Description: Much is known about mechanisms and regulation of phenoxy acid herbicide degradation at the organism level, whereas the effects of environmental factors on the performance of the phenoxy acid degrading communities in soils are much less clear. In a microcosm experiment we investigated the small-scale effect of litter addition on the functioning of the MCPA degrading communities. 14C labelled MCPA was applied and the functional genes tfdA and tfdAα were quantified to characterise bacterial MCPA degradation. We identify the transport of litter compounds as an important process that probably regulates the activity of the MCPA degrading community at the soil–litter interface. Two possible mechanisms can explain the increased tfdA abundance and MCPA degradation below the litter layer: 1) transport of α-ketoglutarate or its metabolic precursors reduces the costs for regenerating this co-substrate and thereby improves growth conditions for the MCPA degrading community; 2) external supply of energy and nutrients changes the internal resource allocation towards enzyme production and/or improves the activity of bacterial consortia involved in MCPA degradation. In addition, the presence of litter compounds might have induced fungal production of litter-decaying enzymes that are able to degrade MCPA as well. ; Includes references ; p. 1879-1887.
    Keywords: Nutrient Availability ; Biodegradation ; Environmental Factors ; Biochemical Pathways ; Soil Bacteria ; Glutaric Acid ; Microbial Genetics ; Plant Litter ; Mcpa (Herbicide) ; Herbicide Residues ; Soil Fungi ; Energy Metabolism ; Enzyme Activity ; Alpha-Ketoglutarates
    ISSN: 0038-0717
    Source: AGRIS (Food and Agriculture Organization of the United Nations)
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 9
    Language: English
    In: Geoderma, March, 2012, Vol.173-174, p.42(8)
    Description: To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.geoderma.2012.01.014 Byline: Ihuaku Anagu, Joachim Ingwersen, Sascha C. Iden, Jens Utermann, Wolfgang Durner, Thilo Streck Keywords: Bayesian parameter estimation; Isotope dilution method; Multiple batch extractions; Sorption isotherm Abbreviations: CV, coefficient of variation; DRAM, delayed rejection adaptive metropolis; EF, modeling efficiency; L/S, liquid to soil ratio; MCMC, markov chain monte carlo; MuBaX, multiple batch extraction; pdf, probability density function; RE, relative error Abstract: The sorption isotherm is the key to modeling the fate of many environmental chemicals in soil. Iden and Durner (2008) proposed a simple method, the multiple batch extractions test (MuBaX), to simultaneously estimate the isotherm parameters and the total desorbable heavy metal contents. The method essentially consists of equilibrating soil suspensions at varying liquid to soil (L/S) ratios, which induces desorption of heavy metals, measuring the solution phase concentrations at equilibrium, and using a model to evaluate the measured data. This study was carried out to test the capability of the proposed method to estimate Freundlich parameters of eight heavy metals for 49 topsoil samples from nine soil types. Heavy metals studied were Cd, Cr, Cu, Mo, Ni, Sb, Tl and Zn. Five L/S ratios (1, 2, 10, 30, and 100Lkg.sup.-1) were used. Parameter estimation was carried out using a Bayesian approach. Although measured solution phase concentrations could be reproduced very well (modeling efficiency, EF, between 0.89 and 0.99), the agreement between total desorbable heavy metal contents estimated by MuBaX and those measured by isotope dilution was quite poor as indicated by negative values of the modeling efficiency. We conclude that the MuBaX method is not well suited for application to strongly sorbing topsoils with relatively low heavy metal contents. Nevertheless, the Bayesian parameter estimation proved useful because it enabled the reliable quantification of the uncertainties in the parameter estimates and was not negatively affected by the existence of local minima of the objective function. Article History: Received 1 August 2010; Revised 21 November 2011; Accepted 9 January 2012
    Keywords: Monte Carlo Methods -- Analysis ; Heavy Metals -- Analysis ; Markov Processes -- Analysis
    ISSN: 0016-7061
    Source: Cengage Learning, Inc.
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 10
    Language: English
    In: Science of the Total Environment, 15 October 2016, Vol.568, pp.1076-1085
    Description: Soils are faced with man-made chemical stress factors, such as the input of organic or metal-containing pesticides, in combination with non-chemical stressors like soil compaction and natural disturbance like drought. Although multiple stress factors are typically co-occurring in soil ecosystems, research in soil sciences on this aspect is limited and focuses mostly on single structural or functional endpoints. A mechanistic understanding of the reaction of soils to multiple stressors is currently lacking. Based on a review of resilience theory, we introduce a new concept for research on the ability of polluted soil (xenobiotics or other chemical pollutants as one stressor) to resist further natural or anthropogenic stress and to retain its functions and structure. There is strong indication that pollution as a primary stressor will change the system reaction of soil, i.e., its resilience, stability and resistance. It can be expected that pollution affects the physiological adaption of organisms and the functional redundancy of the soil to further stress. We hypothesize that the recovery of organisms and chemical-physical properties after impact of a follow-up stressor is faster in polluted soil than in non-polluted soil, i.e., polluted soil has a higher dynamical stability (dynamical stability = 1 / recovery time), whereas resilience of the contaminated soil is lower compared to that of not or less contaminated soil. Thus, a polluted soil might be more prone to change into another system regime after occurrence of further stress. We highlight this issue by compiling the literature exemplarily for the effects of Cu contamination and compaction on soil functions and structure. We propose to intensify research on effects of combined stresses involving a multidisciplinary team of experts and provide suggestions for corresponding experiments. Our concept offers thus a framework for system level analysis of soils paving the way to enhance ecological theory.
    Keywords: Resilience ; Stability ; Resistance ; Pollutants ; Natural Stress ; Copper ; Compaction ; Environmental Sciences ; Biology ; Public Health
    ISSN: 0048-9697
    E-ISSN: 1879-1026
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. Further information can be found on the KOBV privacy pages