Аналіз чинників впливу на процеси функціонування керівної системи підприємств

Мета статті зводиться до вирішення завдання аналізу чинників впливу на керівну систему як регулятор діяльності підприємства та за допомогою використання метода теоретичного аналізу, синтезу та узагальнення розробки їх загальної класифікації.Цель статьи сводится к решению задания анализа факторов влияния на руководящую систему как регулятор деятельности предприятия и с помощью использования метода теоретического анализа, синтеза и обобщения разработки их общей классификации

On the stratigraphic integrity of leaf-wax biomarkers in loess paleosols

Paleoenvironmental and paleoclimate reconstructions based on molecular proxies, such as those derived from leaf-wax biomarkers, in loess-paleosol sequences represent a promising line of investigation in Quaternary research. The main premise of such reconstructions is the synsedimentary deposition of biomarkers and dust, which has become a debated subject in recent years. This study uses two independent approaches to test the stratigraphic integrity of leaf-wax biomarkers: (i) long-chain n-alkanes and fatty acids are quantified in two sediment-depth profiles in glacial till on the Swiss Plateau, consisting of a Holocene topsoil and the underlying B and C horizons. Since glacial sediments are initially very poor in organic matter, significant amounts of leaf-wax biomarkers in the B and C horizons of those profiles would reflect postsedimentary root-derived or microbial contributions. (ii) Compound-specific radiocarbon measurements are conducted on n-alkanes and n-alkanoic (fatty) acids from several depth intervals in the loess section "Crvenka", Serbia, and the results are compared to independent estimates of sediment age. <br><br> We find extremely low concentrations of plant-wax n-alkanes and fatty acids in the B and C horizons below the topsoils in the sediment profiles. Moreover, compound-specific radiocarbon analysis yields plant-wax ¹⁴C ages that agree well with published luminescence ages and stratigraphy of the Serbian loess deposit. Both approaches confirm that postsedimentary, root-derived or microbial contributions are negligible in the two investigated systems. The good agreement between the ages of odd and even homologues also indicates that reworking and incorporation of fossil leaf waxes is not particularly relevant either

Diverse soil carbon dynamics expressed at the molecular level

The stability and potential vulnerability of soil organic matter (SOM) to global change remains incompletely understood due to the complex processes involved in its formation and turnover. Here we combine compound-specific radiocarbon analysis with fraction-specific and bulk-level radiocarbon measurements in order to further elucidate controls on SOM dynamics in a temperate and sub-alpine forested ecosystem. Radiocarbon contents of individual organic compounds isolated from the same soil interval generally exhibit greater variation than those among corresponding operationally-defined fractions. Notably, markedly older ages of long-chain plant leaf wax lipids (n-alkanoic acids) imply that they reflect a highly stable carbon pool. Furthermore, marked 14C variations among shorter- and longer-chain n-alkanoic acid homologues suggest that they track different SOM pools. Extremes in SOM dynamics thus manifest themselves within a single compound class. This exploratory study highlights the potential of compound-specific radiocarbon analysis for understanding SOM dynamics in ecosystems potentially vulnerable to global change

Compound-Specific Radiocarbon Analysis by Elemental Analyzer–Accelerator Mass Spectrometry: Precision and Limitations

[EN]We examine instrumental and methodological capabilities for microscale (10−50μg of C) radiocarbon analysisof individual compounds in the context of paleoclimate and paleoceanography applications, for which relatively high-precisionmeasurements are required. An extensive suite of data for14C-free and modern reference materials processed using differentmethods and acquired using an elemental-analyzer−accelerator-mass-spectrometry (EA-AMS) instrumental setup at ETHZurich was compiled to assess the reproducibility of specific isolation procedures. In order to determine the precision, accuracy,and reproducibility of measurements on processed compounds, we explore the results of both reference materials and threeclasses of compounds (fatty acids, alkenones, and amino acids) extracted from sediment samples. We utilize a MATLAB codedeveloped to systematically evaluate constant-contamination-model parameters, which in turn can be applied to measurementsof unknown process samples. This approach is computationally reliable and can be used for any blank assessment of small-sizeradiocarbon samples. Our results show that a conservative lower estimate of the sample sizes required to produce relativelyhigh-precision14C data (i.e., with acceptable errors of 0.5, a precision of 2% can be achieved for alkenone and fatty acid samples containing≥15 and 10μg of C, respectivel

Transformations in organic sulfur speciation during maturation of Monterey shale: Constraints from laboratory experiments

A series of hydrous pyrolysis experiments were conducted at temperatures ranging from 125 to 360C at 350 bars pressure to examine variations in sulfur speciation during thermal maturation of Monterey shale. The total sediment, kerogen and bitumen from each experiment in addition to unheated representatives were analyzed via x-ray absorption spectroscopy, pyrolysis-gas chromatography, {sup 30}NMR spectrometry, elemental analysis, thin-layer chromatography and reflected light microscopy. Based on these measurements, it was possible to recognize three distinct temperature regimes, within which the type and amount of sulfur in the analyzed fractions underwent transformations: (1) between 150 and 225C significant proportion of kerogen-bound sulfur is lost probably due to the collapse of polysulfide bridges; (2) between 225 and 275C, cleavage of -S-S- and -S-C- linkages within the kerogen is believed to occur, resulting in substantial production of polar sulfur-rich bitumen; (3) above 275C total bitumen yields as well as the proportion of bitumen sulfur decrease, while C-C bond scission leads to increased yields of saturated and aromatic hydrocarbons. The results from this study clearly and quantitatively establish a link between organically-bound sulfur, and more specifically, organic polysulfides, and the low-temperature evolution of soluble petroleum-like products (bitumen) from sulfur-rich source rocks

The Modern Ocean Sediment Archive and Inventory of Carbon (MOSAIC): version 2.0

Marine sediments play a crucial role in the global carbon cycle by acting as the ultimate sink of both terrestrial and marine organic carbon. To understand the spatiotemporal variability in the content, sources, and dynamics of organic carbon in marine sediments, a curated and harmonized database of organic carbon and associated parameters is needed, which has prompted the development of the Modern Ocean Sediment Archive and Inventory of Carbon (MOSAIC) database (http://mosaic.ethz.ch/, last access: 26 July 2023; https://doi.org/10.5281/zenodo.8322094, Paradis, 2023; https://doi.org/10.5168/mosaic019.1, Van der Voort et al., 2019​​​​​​​). MOSAIC version 2.0 has expanded the spatiotemporal coverage of the original database by &gt;400 % and now holds data from more than 21 000 individual sediment cores from different continental margins on a global scale. Additional variables have also been incorporated into MOSAIC v.2.0 that are crucial to interpret the quantity, origin, and age of organic carbon in marine sediments globally. Sedimentological parameters (e.g. grain size fractions and mineral surface area) help understand the effect of hydrodynamic sorting and mineral protection on the distribution of organic carbon, while molecular biomarker signatures (e.g. lignin phenols, fatty acids, and alkanes) can help constrain the specific origin of organic matter. MOSAIC v.2.0 also stores data on specific sediment and molecular fractions, which provide further insight into the processes that affect the degradation and ageing of organic carbon in marine sediments. Data included within MOSAIC are continuously expanding, and version control will allow users to benefit from updated versions while ensuring reproducibility of their findings.</p

Compound-specific radiocarbon dating of the varved Holocene sedimentary record of Saanich Inlet, Canada

Author Posting. © American Geophysical Union, 2004. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Paleoceanography 19 (2004): PA2012, doi:10.1029/2003PA000927.The radiocarbon contents of various biomarkers extracted from the varve-counted sediments of Saanich Inlet, Canada, were determined to assess their applicability for dating purposes. Calibrated ages obtained from the marine planktonic archaeal biomarker crenarchaeol compared favorably with varve-count ages. The same conclusion could be drawn for a more general archaeal biomarker (GDGT-0), although this biomarker proved to be less reliable due to its less-specific origin. The results also lend support to earlier indications that marine crenarchaeota use dissolved inorganic carbon (DIC) as their carbon source. The average reservoir age offset ΔR of 430 years, determined using the crenarchaeol radiocarbon ages, varied by ±110 years. This may be caused by natural variations in ocean-atmosphere mixing or upwelling at the NE Pacific coast but variability may also be due to an inconsistency in the marine calibration curve when used at sites with high reservoir ages.This work was supported by the Netherlands Organization for Scientific Research (NWO) and NSF grants OCE-9907129 and OCE-0137005 (Eglinton)

Contrasts in dissolved, particulate, and sedimentary organic carbon from the Kolyma River to the East Siberian Shelf

Arctic rivers will be increasingly affected by the hydrological and biogeochemical consequences of thawing permafrost. During transport, permafrost-derived organic carbon (OC) can either accumulate in floodplain and shelf sediments or be degraded into greenhouse gases prior to final burial. Thus, the net impact of permafrost OC on climate will ultimately depend on the interplay of complex processes that occur along the source-to-sink system. Here, we focus on the Kolyma River, the largest watershed completely underlain by continuous permafrost, and marine sediments of the East Siberian Sea, as a transect to investigate the fate of permafrost OC along the land–ocean continuum. Three pools of riverine OC were investigated for the Kolyma main stem and five of its tributaries: dissolved OC (DOC), suspended particulate OC (POC), and riverbed sediment OC (SOC). They were compared with earlier findings in marine sediments. Carbon isotopes (δ13C, Δ14C), lignin phenol, and lipid biomarker proxies show a contrasting composition and degradation state of these different carbon pools. Dual C isotope source apportionment calculations imply that old permafrost-OC is mostly associated with sediments (SOC; contribution of 68±10 %), and less dominant in POC (38±8 %), whereas autochthonous primary production contributes around 44±10 % to POC in the main stem and up to 79±11 % in tributaries. Biomarker degradation indices suggest that Kolyma DOC might be relatively degraded, regardless of its generally young age shown by previous studies. In contrast, SOC shows the lowest Δ14C value (oldest OC), yet relatively fresh compositional signatures. Furthermore, decreasing mineral surface area-normalised OC- and biomarker loadings suggest that SOC might be reactive along the land–ocean continuum and almost all parameters were subjected to rapid change when moving from freshwater to the marine environment. This suggests that sedimentary dynamics play a crucial role when targeting permafrost-derived OC in aquatic systems and support earlier studies highlighting the fact that the land–ocean transition zone is an efficient reactor and a dynamic environment. The prevailing inconsistencies between freshwater and marine research (i.e. targeting predominantly DOC and SOC respectively) need to be better aligned in order to determine to what degree thawed permafrost OC may be destined for long-term burial, thereby attenuating further global warming.</p

A critical evaluation of interlaboratory data on total, elemental, and isotopic carbon in the carbonaceous particle reference material, NIST SRM 1649a

Because of increased interest in the marine and atmospheric sciences in elemental carbon (EC), or black carbon (BC) or soot carbon (SC), and because of the difficulties in analyzing or even defining this pervasive component of particulate carbon, it has become quite important to have appropriate reference materials for intercomparison and quality control. The NIST "urban dust" Standard Reference Material? SRM 1649a is useful in this respect, in part because it comprises a considerable array of inorganic and organic species, and because it exhibits a large degree of (14C) isotopic heterogeneity, with biomass carbon source contributions ranging from about 2 % (essentially fossil aliphatic fraction) to about 32 % (polar fraction). A primary purpose of this report is to provide documentation for the new isotopic and chemical particulate carbon data for the most recent (31 Jan. 2001) SRM 1649a Certificate of Analysis. Supporting this is a critical review of underlying international intercomparison data and methodologies, provided by 18 teams of analytical experts from 11 institutions. Key results of the intercomparison are: (1) a new, Certified Value for total carbon (TC) in SRM 1649a; (2) 14C Reference Values for total carbon and a number of organic species, including for the first time 8 individual PAHs; and (3) elemental carbon (EC) Information Values derived from 13 analytical methods applied to this component. Results for elemental carbon, which comprised a special focus of the intercomparison, were quite diverse, reflecting the confounding of methodological-matrix artifacts, and methods that tended to probe more or less refractory regions of this universal, but ill-defined product of incomplete combustion. Availability of both chemical and 14C speciation data for SRM 1649a holds great promise for improved analytical insight through comparative analysis (e.g., fossil/ biomass partition in EC compared to PAH), and through application of the principle of isotopic mass balance.Carrie, L. A., Benner, B. A., Kessler, J. D., Klinedinst, D. B., Klouda, G. A., Marolf, J. V., . . . Schmid, H. (2002). A Critical Evaluation of Interlaboratory Data on Total, Elemental, and Isotopic Carbon in the Carbonaceous Particle Reference Material, NIST SRM 1649a. Journal of Research of the National Institute of Standards and Technology, 107(3), 279-298

Environmental and hydrologic controls on sediment and organic carbon export from a subalpine catchment: insights from a time series

Studies engaging in tracking headwater carbon signatures downstream remain sparse, despite their importance for constraining transfer and transformation pathways of organic carbon (OC) and developing regional-scale perspectives on mechanisms influencing the balance between remineralization and carbon export. Based on a 40-month time series, we investigate the dependence of hydrology and seasonality on the discharge of sediment and OC in a small (350 km2) Swiss subalpine watershed (Sihl River basin). We analyze concentrations and isotopic compositions (δ13C, F14C) of particulate OC and use dual-isotope mixing and machine learning frameworks to characterize and estimate source contributions, transport pathways, and export fluxes. The majority of transferred OC is sourced from plant biomass and soil material. The relative amount of bedrock-derived (petrogenic) OC, abundant in headwater streams, progressively decreases downstream in response to a lack of source material and efficient overprinting with biospheric OC, illustrating rapid organic matter alteration over short distances. Large variations in OC isotopic compositions observed during baseflow conditions converge and form a homogenous mixture enriched in OC and characterized by higher POC-F14C values following precipitation-driven events. Particulate OC isotopic data and model results suggest that storms facilitate surface runoff and the inundation of riparian zones, resulting in the entrainment of loose plant-derived debris and surficial soil material. Although particle transport in the Sihl River basin is mainly driven by hydrology, subtle changes in bedrock erosivity, slope angle, and floodplain extent likely have profound effects on the POC composition, age, and export yields.</p