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24701. 题目: The effect of application of organic manures and mineral fertilizers on the state of soil organic matter and nutrients in the long-term field experiment
文章编号: N18072412
期刊: Journal of Soils and Sediments
作者: Ladislav Men?ík, Luká? Hlisnikovsk?, Lubica Pospí?ilová, Eva Kunzová
更新时间: 2018-07-24
摘要: Purpose: Soil organic matter (SOM) plays an important role in terrestrial ecosystems and agroecosystems. Changes in the agricultural sector in the Czech Republic within the past 25 years have had a negative impact on SOM content and contribute to gradual soil degradation. The aim of this study is to estimate the effect of long-term application of different mineral fertilizers (NPK) and organic manures (manure, cattle slurry) on soil chemical properties (quality of humus, available nutrients, and soil reaction). Materials and methods: Soil samples were collected from Luvisol during two selected periods 1994–2003 and 2014–2016 from long-term field experiment carried out in Prague-Ruzyně (Czech Republic). Average annual temperature is 8.5 °C, and annual precipitations are 485 mm. Different fertilization regimes have been applied for 62 years. The crop rotation was as follows: cereals (45%), root crops (33%) and legumes (22%). Soil analysis—soil organic carbon (SOC) was determined by oxidimetric titration method. Short fractionation method for evaluation of humic substance (HS), humic acid (HA) and fulvic acid (FA) content was used. Absorbance of HS in UV-VIS spectral range was measured by Varian Carry 50 Probe UV-VIS spectrometer. Degree of humification (DH) and color index (Q4/6) were calculated from fractional composition data. Soil reaction was measured by potentiometric method. Available nutrients (phosphorus, potassium, magnesium, calcium) were determined by Mehlich II and Mehlich I methods and by ICP-OES. For data analysis, the following are used: exploratory data analysis, ANOVA, and principal component analysis (PCA). Results and discussion: PCA analysis differentiated fertilizers into two categories: (1) variant NPK (lower quality of humus)—higher acidity, lower SOC and HS content, predomination of FA, higher DH and lower content of available nutrients; (2) variants with organic manures (higher quality of humus)—lower acidity, higher SOC and HS content, predomination of HA, middle DH, and high content of available nutrients. The main result of presented study is to give a synthesis of effect of different type of fertilizers on a sustainable organic matter management in arable soils, with respect to yields, food security and adaptation to predict climate changes. Conclusions: Long-term application of mineral fertilizers (NPK) without organic matter input can accelerate humus mineralization and soil quality degradation with all negative consequences such as (nitrogen leaching, higher availability of toxic element for plants, slow energy for soil microorganisms etc.). Application of organic fertilizers (manure and cattle slurry) helps to achieve the long-term stable yields while maintaining soil at optimum quality (long-term sustainable management with SOM). Principal component analysis is a useful tool for evaluation of soil quality changes.
24702. 题目: Studying of the interaction between peat humic acids and metazachlor using spectroscopy methods
文章编号: N18072411
期刊: Journal of Soils and Sediments
作者: Romualda Bejger, Lilla Mielnik, Ma?gorzata W?odarczyk, Pawe? Nicia
更新时间: 2018-07-24
摘要: Purpose: The analysis covered the interaction of humic acids (HA) isolated from peats with the metazachlor using spectroscopic methods. Materials and methods: Five peatlands have been selected for the study in the southern and northern parts of Poland. Extraction of humic acids (HA1, HA2, HA3, HA4, and HA5) was performed using a procedure recommended by the International Humic Substances Society. Metazachlor 500 SC with metazachlor as a biologically active substance [2-chloro-N-(pyrazol-1-ylmethyl)acet-2′,6′-xylidide] has been used. HA have been assessed on the basis of their elemental composition. Spectroscopic techniques have been used to study the HA structure and their interaction with metazachlor including: UV-visible spectroscopy, dynamic light scattering, and delayed luminescence (DL) Results and discussion: Based on their morphological and chemical properties, the studied peat soils can be classified as follows: (1) Eutric Murshic Sapric Histosols, (2) Eutric Sapric Histosols, (3) Eutric Hemic Histosols, (4) Eutric Fibric Histosols, and (5) Dystric Dranic Hemic Histosols according to the WRB guidelines (2015). Results showed that the largest particle size, measured by E4/6 coefficient, was found in HA2 sample, while the smallest in HA3 sample. The addition of metazachlor to HA solutions reduced the values of E4/6 coefficient by 33 to 72%, while the values of hydrodynamic diameter by 4 to 32%. No significant changes were found between E4/6 after adding of metazachlor to HA solutions. The largest changes in DL intensity, excited both by blue and red light after herbicide addition, were observed in HA2 sample, which is characterized by the largest particle size, the highest oxygen content and CQ value as well as the lowest “aromatization rate” value. Conclusions: The particle sizes of HA molecules measured by E4/6 coefficient do not impact on the particle sizes of HA-herbicide systems measured by the same ratio. The delayed luminescence may become valuable, because it is simple, fast, and sensitive. Additionally, the results show minor errors comparing with chemical methods. This method may provide information about structure and nature of humic acids, as well as their photoreactivity. The using of delayed luminescence in studies of HA-pesticides interaction may enable us to better understand the luminescence properties of HA.
24703. 题目: Seasonal changes in the content of dissolved organic matter in arable soils
文章编号: N18072410
期刊: Journal of Soils and Sediments
作者: Ewa Rosa, Bozena Debska
更新时间: 2018-07-24
摘要: Purpose: The aim of this paper has been to determine the seasonal changes in the content of dissolved organic matter (DOM) in the soils under agricultural use based on assaying changes in dissolved organic carbon (DOC) and dissolved nitrogen (DNt) as well as determining the factors which can define the DOM in soils. Materials and methods: The research has involved the soils under agricultural use sampled in the Kujawsko-Pomorskie province (Poland). Phaeozems and Luvisols were sampled from the depth of 0–30, 30–60, and 60–100 cm, November 2011 through September 2013, in November, March, May, July, and September. The soil samples were assayed for the grain size composition, pH, dry weight content, content of total organic carbon, and total nitrogen. Dissolved organic matter was extracted with 0.004 mol dm3 CaCl2; in the DOM extracts, the content of dissolved organic carbon (DOC) and dissolved nitrogen (DNt) were assayed. The research results were statistically verified. Results and discussion: It has been demonstrated that in the first year of research, the content of dissolved organic carbon in the soils was changing throughout the year. The highest differences in the content of that carbon fraction occurred across the soil sampled in autumn and the soil sampled in spring. In the second year of research, an inverse dependence was noted. DOC was migrating to deeper layers of the soil profile; yet, the migration got more intensive in summer. The content of dissolved nitrogen was not changing significantly throughout the year. Higher DNt content in the surface layer, in general, resulted in a higher content of dissolved nitrogen in deeper profile layer, which could have been due to leaching of the nutrient deep down the soil profile. Conclusions: The content of dissolved organic carbon was significantly related to the content of total organic carbon and total nitrogen. Significant changes in the content of dissolved forms of nitrogen were reported in the profile of Phaeozems due to mineral fertilization and irrigation. The soils where irrigation and higher nitrogen rates had been applied demonstrated a higher content and share of soluble forms of nitrogen, as compared with the soils non-irrigated and the soils where lower nitrogen rates had been supplied.
24704. 题目: Quantitative and qualitative characterisation of humic products with spectral parameters
文章编号: N18072409
期刊: Journal of Soils and Sediments
作者: Ekaterina Filcheva, Mariana Hristova, Pavlina Nikolova, Todorka Popova, Konstantin Chakalov, Valentin Savov
更新时间: 2018-07-24
摘要: Purpose: The application of different humic products for the treatment of soils and plants has increased in recent years. The characteristics of humic products, such as the content and composition of organic carbon and the maturity, provide valuable information which is essential for an adequate application. Such information is crucial for manufacturers, business consultants and users involved in the production, distribution and implementation of humic products. This article presents the correlation between the quantitative indicators of commercial humic products and their spectral characteristics via measurements in the ultraviolet spectrum at 300 nm, in the visible area at 445 and 665 nm and in the near-infrared spectrum at 850 nm. Materials and methods: We evaluated humic products (liquid and solid) of different origins. Via wet combustion, the content of total organic carbon in humic products can be determined. The precipitation of humic acids from the starting solution determines the composition of the humic products in terms of humic acids (HAs) and fulvic acids (FAs). The dissolution of HAs determines their concentration by titration, while the specific extinction can be assessed via spectrophotometry via measuring the absorption of HAs spectra at the following wavelengths: 300, 465, 665 and 850 nm. The degree of aromaticity and condensation of humic products determines the optical density of the HAs via the E4/E6 ratio. Results and discussion: The content of total organic carbon varied widely from 0.55 to 37.5% across all groups. The content of carbon in HAs, as a percentage of the total carbon in fulvic-type humic products, ranged from 1.29 to 16.00%, while in humic-type products, it ranged from 51.43 to 91.92%. The minimum value of the E4/E6 ratio was 2.97, while the maximum value was 6.35. We observed a direct relationship between the dominant type of acids in humic products and the E4/E6 ratio. Conclusions: The optical density of HAs indicates their quality characteristics. The presented optical characteristics for humic products show that there is a direct relationship, especially between HAs/FAs and E4/E6 ratios. Measurement at 300 nm (E300) in the near-ultraviolet area and at 850 nm (E850) in the near-infrared area can increase the range of the spectral study.
24705. 题目: Qualitative and quantitative soil organic matter estimation for sustainable soil management
文章编号: N18072408
期刊: Journal of Soils and Sediments
作者: Jolanta Kwiatkowska-Malina
更新时间: 2018-07-24
摘要: Purpose: The aims of this paper were to review tools and methods for qualitative and quantitative evaluation of soil organic matter (SOM) coming from diverse egzogenic sources for effective soil management, and to introduce a new approach to predict dynamics of SOM transformations, especially humification, as a key process in the formation of humic substances (HSs). Materials and methods: A review of existing literature is presented on tools and methods for qualitative and quantitative assessment of organic matter in soil originating from various sources for reasonable soil management, attempting to provide a better understanding of the advances in organic matter transformations and new research directions for modeling. Diverse tools and methods for qualitative and quantitative evaluation of organic matter in soil coming from diverse sources have been adopted so far to express transformation processes. Results and discussion: For the qualitative analysis of SOM and humic acids (HAs), the analytical techniques are applied, e.g., HPSEC, NMR, and ESI-FTICRMS. The quantitative analysis is done through the following parameters: humification index (HI), humification degree (HD), and humification rate (HR). These analyses indicated that because of lack of reliable data from sufficiently long-term experiments, mathematical modeling may be applied as a numerical tool for quantitative estimation and prediction of humification of SOM. The effective soil management should include soil properties as well as different functions: food production, nutrient and water cycling, storage, filtrating, buffering, biological habitat, gene pool, source of raw materials, climate regulations, heritage, platform for man-made structure. The soil utility value should be evaluated through the SOM qualitative and quantitative analysis of organic carbon and total nitrogen. Knowledge about dynamics of SOM transformations is essential, particularly in the context of stability and efficiency of different sources of organic matter applied into soil. A qualitative understanding of SOM dynamics transformations along with modeling for quantitative assessment of HS formation should be used to develop sustainable soil management. The modeling may be considered as a tool for predicting SOM humification dynamics and consequently the formation of HSs from the diverse sources. The existing archival data from a long-term experiment may be used to build and calibrate the reliable mathematical model of SOM humification. Conclusions: Managing of SOM remains a sound basis for maintaining soil in a good condition for optimizing productivity. The development of land management strategies to optimize both the increase of soil organic carbon levels and the recycling of nutrients from SOM needs to be a priority. This should include policy makers and other users as well.
24706. 题目: Particle and structure characterization of fulvic acids from agricultural soils
文章编号: N18072407
期刊: Journal of Soils and Sediments
作者: Aleksandra Ukalska-Jaruga, Guillaume Debaene, Bo?ena Smreczak
更新时间: 2018-07-24
摘要: Purpose: Structural studies on fulvic acids (FAs) are of significant importance since FAs are involved in many environmentally important processes, such as adsorption and transportation of nutrients, trace elements, and organic pollutants. Interactions between suspended and dissolved soil components are controlled by a variety of attractive and repulsive interparticle forces influenced partially by FA properties. The aim of this paper is a detailed characterization of FAs derived from agricultural soils varied with physicochemical properties. Materials and methods: Forty topsoils (pHKCL = 3.8–7.8, clay content = 0–6%, and TOC = 7.0–187.2 g kg-1) were collected from rural area. Fulvic acids (FAs) were isolated according to the IHSS method. The overall FA solutions were purified by nonionic macroporous acrylic ester resin (DAX-8), and the organic carbon content in FA fraction (FA-OC) was determined by a liquid C–N analyzer. The particle size diameter (PSD) and polydispersity (PDI) were analyzed by a dynamic light scattering technique, while the zeta potential (ZP) was measured using an electrophoretic light scattering method. Spectroscopic properties of FAs, including occurrence and distribution of functional groups, were investigated by near-IR spectroscopy. Results and discussion: Agricultural soils differed substantially, with FA-OC content ranging from 0.6 to 8.8 g kg-1 that accounted for 0.5 to 22.6% of TOC. The PSD exhibited wide range of particle size (0.2 to 69.6 nm) and was characterized by different polydispersity (14–183.1%). The ZP described the behavior, and surface charge of FA particles varied from 1.7 to + 3.3 mV. Low ZP characterized 77% of FAs and indicated the ease of aggregate formation and intermolecular connections. The measured ZP also showed that suspended organic particles of FAs had both positive and negative charges, which was confirmed by the spectroscopic analysis. The presence of negative charges on FA particle surfaces was connected with the occurrence of phenol and carboxyl groups while positive charge with amine. Conclusions: Detailed characterization of FAs from agricultural soils confirms their heterogeneous and complex nature. The results indicate that FAs mainly exist as small molecules that form molecular aggregates or associations in solutions. FA in a solution of a similar ionic strength may be positively or negatively charged due to its chemical structure and aggregate behavior which affects their properties in the soil.
24707. 题目: Mutual relations between PAHs derived from atmospheric deposition, enzymatic activity, and humic substances in soils of differently urbanized areas
文章编号: N18072406
期刊: Journal of Soils and Sediments
作者: El?bieta J. Bielińska, Barbara Futa, Aleksandra Ukalska-Jaruga, Jerzy Weber, Szymon Chmielewski, Sylwia Weso?owska, Agnieszka Mocek-P?óciniak, Krzysztof Patkowski, Lilla Mielnik
更新时间: 2018-07-24
摘要: Purpose: The aim of this study was to determine the mutual relations between polycyclic aromatic hydrocarbons (PAHs) originated from atmospheric emissions and enzymatic activity and humic substances in soils at differently urbanized area, on an example of the Lublin city, east Poland. Materials and methods: The chosen areas represented three differently urbanized environments: old tenement houses and modern residential blocks, mixture of different building and rural landscape, and typical rural environment with smallholding farms, respectively. On each of the urban, suburban, and rural areas, one representative plot was chosen on fallow lands classified as luvisol derived from loess. The soil samples were collected from the top 25 cm layer. The following properties were determined: pH, organic carbon, total nitrogen, humic and fulvic acids, PAHs content (14 PAHs from US EPA list), and the activities of the following enzymes: dehydrogenases, acid phosphatase, alkane phosphatase, protease, and urease. Results and discussion: Higher contents of organic C and total N were found in the rural soil samples. The share of humic acid was similar in all soils investigated, ranging from 19.38 to 25.27%, while fulvic acid values differ significantly between urban and rural areas. The urban soils indicated much lower share of fulvic acids (9.78–10.99%) than those of rural (29.02–29.32%). Consequently, the values of the CHA:CFA ratio of the urban soil were approximately two times higher than those of the rural soil. The results showed that both the rate of humification and the activity of dehydrogenases, acid phosphatase, alkaline phosphatase, and proteases in the soils increased in the following sequence: urban < suburban < rural. Conclusions: The results showed that an increase of PAHs in the urbanized areas affect other soil properties. The phenanthrene/anthracene and fluoranthene/pyrene ratios pointed to coal combustion as the principal source of PAHs in the investigated soils. The PAH content in the urbanized area inhibit humification processes in the soil and the activity of dehydrogenases, acid phosphatase, alkaline phosphatase, and proteases.
24708. 题目: Molecular composition of the Humeome extracted from different green composts and their biostimulation on early growth of maize
文章编号: N18072405
期刊: Plant and Soil
作者: Hiarhi Monda, Vincenza Cozzolino, Giovanni Vinci, Marios Drosos, Davide Savy, Alessandro Piccolo
更新时间: 2018-07-24
摘要: Background and aims: The use of composted agricultural wastes as source of biostimulant compounds provides an added value to the recycling of biomasses. This study aims to expand the knowledge on the relationship between molecular composition and bioactivity of the Humeome extracted from green composts. Methods: Humic acids (HA) were isolated from the following green composts: 1. artichoke (HA-CYN), 2. artichoke/fennel (HA-CYNF), 3. tomato (HA-TOM), 4. cauliflower (HA-CAV). The compost-extracted Humeome was characterized by solid- and liquid-state Nuclear Magnetic Resonance (NMR) Spectroscopy, Infrared Spectrometry, pyrolysis-gas chromatography/mass spectrometry (Pyr-GC/MS), elemental and thermal analyses (TGA, DSC), and the effects on maize (Zea mays L.) seedling growth (roots and shoots) and leaves chlorophyll content, investigated at three different concentration rates (25, 50 and 100 mg L-1 C). Results: All Humeomes from green composts generally favored plant growth, with HA-CYN and HA-CAV being active at small concentrations, while HA-TOM and HA-CYNF at greater application rates. The response of HA-CYN and HA-CAV was attributed to their large hydrophobicity that may favor adhesion to roots surfaces and concomitant release of bioactive molecules, whereas the toxicity of phenolic moieties in HA-TOM and HA-CYNF could only be mitigated by tighter intermolecular aggregation at greater concentrations. Conclusion: Bioactivity of Humeomes from green composts appeared to be related to their composition and consequent conformational structure in solution, whose flexibility determines the potential release of bioactive molecules that directly or indirectly influence plants development.
24709. 题目: Humic matter: basis for life—a plea for humics care
文章编号: N18072404
期刊: Journal of Soils and Sediments
作者: Fritz H. Frimmel, Gudrun Abbt-Braun
更新时间: 2018-07-24
摘要: Purpose: Humic matter (HM) is the leftover from life and at the same time the source for new life. The resulting complex system with many interactions has become a crucial part for the anthropocene and by this for the survival of mankind. Based on the results of the application of advanced analytical tools, the structures, reactions and interactions of HM are discussed. Materials and methods: HM was investigated from different water samples (ground water, bog lake, waste water effluent). Fulvic acids (FA) and humic acids (HA) were isolated from a bog lake and from waste water effluent according to the XAD-method described by the International Humic Substances Society. Parameters like dissolved organic carbon (DOC), spectral absorption coefficient at λ = 254 nm (SAK), AOX (on activated carbon absorbable organically bound halogen) and THM (trihalomethanes) were determined according to ISO standard methods. For additional characterization, size exclusion chromatography coupled with online DOC detection and solid-state NMR were applied. The degradation of HM was studied by heterogeneous photocatalysis with titanium dioxide. Membrane separation, done as ultra- and nanofiltration, was used to characterize different size fractions of HM. Results and discussion: The water solubility and hence the omnipresence of HM in aquatic systems opens the door for obtaining well-defined samples for experiments with meaningful results. Information on transport properties and reactivity, derived from the molecular size of HM, was obtained by using membrane filtration at different pore sizes. Photocatalytic degradation of HM was investigated by irradiation of suspensions with TiO2 as catalyst. Small organic acids (e.g. formic acid) were formed before total mineralisation occurred. Conclusions: It can be concluded that the properties of HM are well derivable from their molecular data. The resulting character of HM with respect of the human environment seems to be obviously ambivalent and asks for a sound understanding and proper management to support life in a sustainable way.
24710. 题目: Humic acid and biochar as specific sorbents of pesticides
文章编号: N18072403
期刊: Journal of Soils and Sediments
作者: Irmina ?wiel?g-Piasecka, Agnieszka Medyńska-Juraszek, Maria Jerzykiewicz, Magdalena D?bicka, Jakub Bekier, El?bieta Jamroz, Dorota Kawa?ko
更新时间: 2018-07-24
摘要: Purpose: The aim of the research was to compare the effect of two types of organic sorbents—humic acid (HA) and biochar (BC)—in sorption-desorption processes of different polar pesticides, which residues are commonly present in arable soils and are potentially harmful for the environment. It also aims to advance the understanding of behavior of both ionizable and nonionizable pesticides in the presence of BC and HA in soils. Materials and methods: Three different classes of pesticides were investigated: carbamates (carbaryl and carbofuran), phenoxyacetic acids (2,4-dichlorophenoxyacetic acid (2,4-D) and 4-chloro-2-methylphenoxyacetic acid (MCPA)), and aniline derivatives (metolachlor). Investigated humic acid was extracted by Shnitzer’s method from topsoil horizon of arable Gleyic Phaeozem. Biochar was produced from wheat straw in gasification process at 550 °C, remaining 30 s in the reactor. To obtain the experimental goal structural properties of both sorbents were determined and sorption-desorption experiments conducted. To the investigated organic matter samples (HA or BC), 10 or 15 mg L-1 pesticide solutions in 10 mM CaCl2 were added and the mixtures were shaken for 24 h. Afterwards, the samples were centrifuged and supernatants analyzed by LC-MS/MS for the pesticide content. Analogous experiment was performed for desorption studies (samples refilled with 10 mM CaCl2). Results and discussion: Humic acids exhibited strong affinity for the ionic substances, for which high-percentage uptake (74.6 and 67.9% initial dose of 2,4-D and MCPA, respectively) was obtained. Retention of nonionic carbamates on HA was much weaker (35.4% of carbofuran and 10.2% of carbaryl sorbed). Sorption of carbamates to BC was significantly reduced (76.4–84.3%) by the alkaline hydrolysis. Metolachlor was bound comparably strong both by HA (72.9%) and BC (70.2%), although different mechanisms governed its sorption. Noticeable desorption occurred only in the case of 2,4-D bound to HA (over 50%), whereas other studied compounds were released from HA within the range of 4.4–10.8% of the dose sorbed. Oppositely to HA, desorption of all studied pesticides from BC was completely inhibited, except for 2,4-D (3.7% desorbed). Conclusions: Investigated humic acid has high affinity to polar, ionic pesticides of high water solubility, which are sorbed via specific interactions with HA functional groups. Studied biochar, due to its moderately hydrophobic character, preferentially attracts nonionic pesticides of relatively high logP values and low water solubility. Hydrophobic bonding is postulated as a main mechanism of their attraction to BC. Besides sorbent structural properties, pH is the main factor governing sorption equilibria in the studied mixtures.
24711. 题目: Evaluation of the possibilities of using humic acids obtained from lignite in the production of commercial fertilizers
文章编号: N18072402
期刊: Journal of Soils and Sediments
作者: Marta Huculak-M?czka, Józef Hoffmann, Krystyna Hoffmann
更新时间: 2018-07-24
摘要: Purpose: Technological progress and high market demand contributed to a significant interest in the production of fertilizers based on humic acids. The aim of this study was to evaluate the possibilities of using humic acids obtained from lignite in the production of new commercial products. For this purpose, it is necessary to determine the quality standard requirements for such material. Properties of humic acids depend on source of origin as well as method of its extraction. Materials and methods: The humic acids were extracted from polish deposit of lignite–Sieniawa Lubuska by alkaline extraction using for this purpose six kinds of extractants: 0.1 M NaOH and 0.25 M NaOH, 0.1 M KOH and 0.25 M KOH, and 0.1 M Na4P2O7 and 0.25 M Na4P2O7. The humic samples were used in solid powder form and characterized by UV-Vis spectroscopy, 13C NMR spectroscopy, fluorescence spectroscopy, and thermal analysis. Results and discussion: The determining factor influencing a degree of humic acids extraction from lignite and their structure is type of extractant. The largest efficiency of extraction (about 50%) was obtained with the use of NaOH solutions. All examined humic acids were generally characterized by simple and heterogeneous molecularly structure with low molecular weight and low aromatic polycondensation. Therefore, it can be concluded that humic acids extracted with NaOH and KOH solutions are less condensed than those extracted with Na4P2O7 solutions. It can suggest that humic acids obtained from lignite using solutions of Na4P2O7 are characterized by a low transformation degree and greater amount of carboxyl groups. Conclusions: Low rank coal can be successfully used in agriculture as a rich source of humic acids. Reagent used in their extraction, apart from high efficiency should have a neutral impact on their structure. Studies on the physicochemical properties of humic acids can be helpful in predicting behaviors of such fertilizer components in the environment and in inventing new products taking the principles of sustainable development into consideration.
24712. 题目: Dissolved organic matter, nutrients, and bacteria in Antarctic soil core from Schirmacher Oasis
文章编号: N18072401
期刊: Journal of Soils and Sediments
作者: Viia Lepane, Kai Künnis-Beres, Enn Kaup, Bhupesh Sharma
更新时间: 2018-07-24
摘要: Purpose: This study focuses on the application of HPLC in dissolved organic matter (DOM) research in Antarctic environment together with nutrients and heterotrophic bacteria (HB) analyses. The specific aims were to investigate changes in DOM components characteristics and in nutrients in soil core from ground active layer and upper permafrost, to relate obtained data to active heterotrophic bacteria records after applying statistical data treatment methods, and to explore the potential impact of environment. Materials and methods: A single Antarctic 1.9-m deep soil core drilled at a site without human impact from Schirmacher Oasis, located 70° 46′ 02″ S and 11° 45′ 11″ E, was explored. The chromophoric DOM (CDOM) was characterized by soil water analysis using multi-wavelength HPLC. Total organic carbon and total nitrogen were determined by elemental analysis, the total phosphorus by inductively coupled plasma spectrometry. The vertical changes in those nutrients and their ratios were investigated. The microbiological analysis was accomplished through the determination of psychrotrophic and psychrophilic aerobic HB numbers by colony-forming units counting method, and by epifluorescence microscopy examination. Cluster analysis using the Ward method and principal component analysis was performed on the chromatographic and microbiology data to reveal similar layers in studied soil core. Results and discussion: In active soil layer, the CDOM was missing thus indicating rather active decomposition of organic material or organic debris by the local microbial community. In deep permafrost layers, the quantity of CDOM preserved in soil water increased. The content of total organic carbon in soil was low, between 0.05 and 0.2%, and decreased down the core. The vertical changes in nutrients (total N and P), the ratios C/N and C/P, followed total organic carbon profile suggesting similar sources. Microbiological analyses showed decreasing vertical concentrations of active HB. Statistical data treatment methods enabled clustering of soil core into three zones according to depth. Conclusions: The obtained results contribute to better understanding of organic carbon-related processes in an almost un-polluted Antarctic environment. The CDOM, macronutrients, C/N, C/P, and HB profile characteristics of the Antarctic soil core clearly demonstrate the effect of environment (active or permafrost soil layers). The study demonstrated that combining HPLC with multi-wavelength detection and microbial analyses with statistical data treatment is potentially a promising tool of investigating changes in Antarctic soil DOM and in soil waters generally.
24713. 题目: Assimilation of ancient organic carbon by zooplankton in Tibetan Plateau lakes is depending on watershed characteristics
文章编号: N18072306
期刊: Limnology and Oceanography
作者: Y.Su, E.Hu, Z.Liu, E.Jeppesen, J. J.Middelburg
更新时间: 2018-07-23
摘要: Ancient (i.e., radiocarbon depleted) organic carbon (OC) is exported from ice sheet, glacier, and permafrost systems and may be buried, respired, or assimilated in downstream aquatic systems. Few studies have explored the potential use of this ancient OC in lake food webs. We combined natural abundance radiocarbon and stable carbon isotope data (Δ14C and δ13C) to study ancient OC utilization by zooplankton in six lakes covering a large climate gradient on the central and peripheral Tibetan Plateau. A depleted Δ14C signature of dissolved and particulate OC was found in the inflowing streams and lakes, ranging from – 49‰ to – 569‰, corresponding to radiocarbon ages between 403 yr and 6757 yr. The Δ14C values for zooplankton in the lakes ranged from – 45‰ to – 264‰, reflecting that zooplankton obtain 14C‐depleted signatures through assimilation of ancient OC and/or indirectly through consumption of phytoplankton or aquatic plant utilizing 14C‐depleted inorganic carbon. Moreover, ancient OC from inflowing streams contributed more to zooplankton diets in the temperate glacier area than in the cold glacier area. Assimilation of ancient OC by zooplankton in lakes is not only affected by drainage basin characteristics, such as the recharge coefficient of the lake, but also by the biogeochemical properties of OC. Use of ancient OC by zooplankton in high‐altitude lakes may constitute an important link between the contemporary aquatic food webs and the glaciated watersheds. Our findings have important implications for the contribution of ancient carbon to the modern lake food webs of high‐altitude and polar lakes.
24714. 题目: Sorption of chlorinated hydrocarbons to biochars in aqueous environment: Effects of the amorphous carbon structure of biochars and the molecular properties of adsorbates
文章编号: N18072305
期刊: Chemosphere
作者: Weifeng Chen, Ran Wei, Jinzhi Ni, Liuming Yang, Wei Qian, Yusheng Yang
更新时间: 2018-07-23
摘要: Currently, the role of amorphous carbon structure (ACS) in sorption of chlorinated hydrocarbons (CHs) to biochars remains little known. Therefore, three CHs (1,1,2,2-tetrachloroethane, 1,3,5-trichlorobenzene and γ-hexachlorocyclohexane) with different molecular properties were selected as model adsorbates to investigate the effect of ACS on sorption of CHs to biochars produced at seven different pyrolysis temperatures (300–900 °C). There were two main mechanisms for ACS controlling the sorption of CHs. First, the polar sites on ACS are hydrophilic, CHs with greater polarity could strongly compete with the water molecule for the hydrophilic sites. Second, ACS of low temperature (300–400 °C) produced biochars possessing the natural organic matter (NOM)-like structure occupied some hydrophobic sites on condensed graphitic structure (CGS) of biochars. CHs with great hydrophobicity possibly seized the hydrophobic sorption sites on CGS from the NOM-like structure. Therefore, ACS of biochar was more benefit for sorption of strong polar CHs (1,1,2,2-tetrachloroethane: π = 0.95; LogKow = 2.39) or strong hydrophobic CHs (1,3,5-trichlorobenzene: π = 0.70; LogKow = 4.19) than CHs (γ-hexachlorocyclohexane: π = 0.68; LogKow = 3.72) with relatively low polarity and hydrophobicity. The result reflects that the interaction between NOM and natural black carbon/biochars in soil and water environment possibly plays the similar role in controlling the environmental behavior of various polar or hydrophobic organic pollutants. Moreover, with increasing concentration of adsorbate (Ce), the first mechanism enhanced, while the second mechanism weakened. This study gives a deep insight into the roles of ACS of biochars in controlling the fate and availability of CHs with different molecular properties in environment.
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24715. 题目: Sedimentary alkalinity generation and long-term alkalinity development in the Baltic Sea
文章编号: N18072304
期刊: Biogeosciences
作者: Erik Gustafsson, Mathilde Hagens, Xiaole Sun, Daniel C. Reed, Christoph Humborg, Caroline P. Slomp, Bo G. Gustafsson
更新时间: 2018-07-23
摘要: Enhanced release of alkalinity from the seafloor, principally driven by anaerobic degradation of organic matter under low-oxygen conditions and associated secondary redox reactions, can increase the carbon dioxide (CO2) buffering capacity of seawater and therefore oceanic CO2 uptake. The Baltic Sea has undergone severe changes in oxygenation state and total alkalinity (TA) over the past decades. The link between these concurrent changes has not yet been investigated in detail. A recent system-wide TA budget constructed for the past 50 years using BALTSEM, a coupled physical-biogeochemical model for the whole Baltic Sea area, revealed an unknown TA source. Here we use BALTSEM in combination with observational data and one-dimensional reactive transport modelling of sedimentary processes in the F r Deep, a deep Baltic Sea basin, to test whether sulfate reduction coupled to iron (Fe) sulfide burial can explain the missing TA source in the Baltic Proper. We calculated that this burial can account for 26% of the missing source in this basin, with the remaining TA possibly originating from unknown river inputs or submarine groundwater discharge. We also show that temporal variability in the input of Fe to the sediments since the 1970s drives changes in sulfur burial in the F r Deep, suggesting that Fe availability is the ultimate limiting factor for TA generation under anoxic conditions. The implementation of projected climate change and two nutrient load scenarios for the 21st century in BALTSEM shows that reducing nutrient loads will improve deep water oxygen conditions, but at the expense of lower surface water TA concentrations, CO2 buffering capacities and faster acidification. When these changes additionally lead to a decrease in Fe inputs to the sediment of the deep basins, anaerobic TA generation will be reduced even further, thus exacerbating acidification. This work highlights that Fe dynamics play a key role in the release of TA from sediments where Fe sulfide formation is limited by Fe availability, as exemplified for the Baltic Sea. Moreover, it demonstrates that burial of Fe sulfides should be included in TA budgets of low oxygen basins.
24716. 题目: Global soil organic carbon removal by water erosion under climate change and land use change during AD?1850–2005
文章编号: N18072303
期刊: Biogeosciences
作者: Victoria Naipal, Philippe Ciais, Yilong Wang, Ronny Lauerwald, Bertrand Guenet, Kristof Van Oost
更新时间: 2018-07-23
摘要: Erosion is an Earth system process that transports carbon laterally across the land surface and is currently accelerated by anthropogenic activities. Anthropogenic land cover change has accelerated soil erosion rates by rainfall and runoff substantially, mobilizing vast quantities of soil organic carbon (SOC) globally. At timescales of decennia to millennia this mobilized SOC can significantly alter previously estimated carbon emissions from land use change (LUC). However, a full understanding of the impact of erosion on land–atmosphere carbon exchange is still missing. The aim of this study is to better constrain the terrestrial carbon fluxes by developing methods compatible with land surface models (LSMs) in order to explicitly represent the links between soil erosion by rainfall and runoff and carbon dynamics. For this we use an emulator that represents the carbon cycle of a LSM, in combination with the Revised Universal Soil Loss Equation (RUSLE) model. We applied this modeling framework at the global scale to evaluate the effects of potential soil erosion (soil removal only) in the presence of other perturbations of the carbon cycle: elevated atmospheric CO2, climate variability, and LUC. We find that over the period AD1850–2005 acceleration of soil erosion leads to a total potential SOC removal flux of 74±18PgC, of which 79%–85% occurs on agricultural land and grassland. Using our best estimates for soil erosion we find that including soil erosion in the SOC-dynamics scheme results in an increase of 62% of the cumulative loss of SOC over 1850–2005 due to the combined effects of climate variability, increasing atmospheric CO2 and LUC. This additional erosional loss decreases the cumulative global carbon sink on land by 2Pg of carbon for this specific period, with the largest effects found for the tropics, where deforestation and agricultural expansion increased soil erosion rates significantly. We conclude that the potential effect of soil erosion on the global SOC stock is comparable to the effects of climate or LUC. It is thus necessary to include soil erosion in assessments of LUC and evaluations of the terrestrial carbon cycle.
24717. 题目: Dissolved organic matter in coastal rainwater: Concentration, bioavailability and depositional flux to seawater in southeastern China
文章编号: N18072302
期刊: Marine Chemistry
作者: Hongyan Bao, Yueyuan Yi, Chao Wang, Robert G.M. Spencer, Xun Deng, Weidong Guo
更新时间: 2018-07-23
摘要: Forty-seven precipitation samples were collected between March 2011 and May 2012 in Xiamen, southeastern China to examine the concentration, bioavailability and depositional flux of dissolved organic matter (DOM) in rainwater. Fluorescence excitation-emission (EEM) spectra of DOM were also determined to trace compositional changes during biodegradation experiments to assess which components of the DOM pool are biolabile. Rainwater dissolved organic carbon (DOC) concentrations ranged from 8.5 to 932 μM, with a volume-weighted average concentration of 128 μM. The fraction of biolabile DOC (BDOC%) ranged from 16 to 91% with an average of 46 ± 17%. The biodegradation rate of rainwater DOC followed a first-order exponential curve. During biodegradation experiments, protein-like fluorescence decreased and humic-like fluorescence remained constant or increased. Both DOC and BDOC concentration showed a dilution effect in relation to rainfall amount. Rainwater with continental trajectories typically had higher DOC concentrations than from marine trajectories, while, in contrast, the BDOC% didn't show significant differences among trajectories. Winter rainwater DOC concentration was significantly higher, while BDOC% was lower than other seasons, which may be related to greater relative fossil fuel inputs, particularly from coal burning in northern China. The depositional flux of rainwater DOC into Xiamen Bay was estimated to be 2.1 Gg C yr 1, and the rainwater BDOC flux to Xiamen Bay was approximately 35% of that discharged from the Jiulong River. Our results highlight that precipitation inputs play a significant role in supplying BDOC to the ocean with ramifications for marine food webs.
24718. 题目: Effects of short- and long-term exposures of humic acid on the Anammox activity and microbial community
文章编号: N18072301
期刊: Environmental Science and Pollution Research
作者: Khadija Kraiem, Mohamed Ali Wahab, Hamadi Kallali, Andrea Fra-vazquez, Alba Pedrouso, Anuska Mosquera-Corral, Naceur Jedidi
更新时间: 2018-07-23
摘要: Humic acid has a controversial effect on the biological treatment processes. Here, we have investigated humic acid effects on the Anammox activity by studying the nitrogen removal efficiencies in batch and continuous conditions and analyzing the microbial community using Fluorescence in situ hybridization (FISH) technique. The results showed that the Anammox activity was affected by the presence of humic acid at a concentration higher than 70 mg/L. In fact, in the presence of humic acid concentration of 200 mg/L, the Anammox activity decreased to 57% in batch and under continuous condition, the ammonium removal efficiencies of the reactor decreased from 78 to 41%. This reduction of Anammox activity after humic acid addition was highlighted by FISH analysis which revealed a considerable reduction of the abundance of Anammox bacteria and the bacteria living in symbiosis with them. Furthermore, a total inhibition of Candidatus Brocadia fulgida was observed. However, humic acid has promoted heterotrophic denitrifying bacteria which became dominant in the reactor. In fact, the evolution of the organic matter in the reactor showed that the added humic acid was used as carbon source by heterotrophic bacteria which explained the shift of metabolism to the favor of heterotrophic denitrifying bacteria. Accordingly, humic acid should be controlled in the influent to avoid Anammox activity inhibition.
24719. 题目: Short-term effects of loosening and incorporation of straw slurry into the upper subsoil on soil physical properties and crop yield
文章编号: N18072207
期刊: Soil and Tillage Research
作者: Gizachew Tarekegn Getahun, Thomas K?tterer, Lars Juhl Munkholm, Mohammed Masud Parvage, Thomas Keller, Katrin Rychel, Holger Kirchmann
更新时间: 2018-07-22
摘要: Subsoils that are compacted, nutrient-poor or low in soil organic matter (SOM) often limit crop growth and yield. Improvement of subsoil conditions by deep loosening is laborious and expensive and its positive effect may not last. This study investigated the effect of deep loosening and injection of slurry made from cereal straw (30 Mg dry mass ha 1) at 25–34 cm depth on soil properties and crop performance in a Swedish field experiment that started in autumn 2015 and monitored soil and crop properties during 2016. Loosening + straw incorporation into subsoil resulted in significantly higher soil organic carbon (SOC) content, potential plant-available water and porosity and lower bulk density (BD) in spring 2016 compared with the control. In autumn 2016, penetrometer resistance (PR) and BD were both significantly lower and SOC and porosity were significantly higher in the loosening + straw treatment compared with the control and loosening only (29–34 cm). Furthermore, BD was significantly lower in the loosening + straw treated subsoil than in the top soil layer of the control (0–10 cm). Observations indicated that more continuous pores were found in the loosening + straw treatment than in other treatments. Roots and soil faunas were found more frequently where straw was incorporated. Grain yield increased by 5.6% due to loosening + straw addition (P = 0.03) and by 4% due to loosening only (P = 0.06). These results indicate that loosening + straw input into upper subsoil had a positive short-term influence on soil physical properties, potential plant-available water and grain yield. Straw addition prolonged the positive effect of loosening.
24720. 题目: Nanoremediation of cadmium contaminated river sediments: Microbial response and organic carbon changes
文章编号: N18072206
期刊: Journal of Hazardous Materials
作者: Wenjing Xue, Zhiwei Peng, Danlian Huang, Guangming Zeng, Jia Wan, Rui Xu, Min Cheng, Chen Zhang, Danni Jiang, Zhengxun Hu
更新时间: 2018-07-22
摘要: The application of nanomaterials to contaminated river sediments could induce important changes in the speciation of heavy metals with potential impacts on ecosystem. Here, rhamnolipid (RL)-stabilized nanoscale zero-valent iron (RNZVI) was conducted to test its potential performance in changing the mobility and speciation of cadmium (Cd) in river sediments, with consideration of the influences of microbial community and organic carbon (OC). Compared to NZVI, RNZVI was more effective in transforming labile Cd to stable fraction with a maximum residual concentration increasing by 11.37 mg/kg after 42 days of incubation. Bacterial community structure was tracked using high-throughput sequencing of 16S rRNA genes. Results indicated that the application of RNZVI changed the bacterial community structure and increased the relative abundance of Fe(III)-reducing bacteria, which could redistribute Fe combined Cd into a more stable Fe mineral phase. The contents of OC were gradually decreased and became stable, might resulting from OC bioavailability’s being stimulated by RNZVI through changing the bacterial community composition. This study indicates that abiotic process (i.e., from reaction with NZVI) and biotic process fueled by RNZVI lead to the immobilization of Cd in river sediments.
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