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25821. 题目: Concentration, characterization and risk assessment of polycyclic aromatic hydrocarbons (PAHs) and organochlorine pesticides (OCPs) in soils from the Corn Belt of Northeast China
文章编号: N19112208
期刊: European Journal of Soil Science
作者: Zucheng Wang, Shasha Liu, Kaijun Lu, Xiaoyun Xu, Tianyu Zhang
更新时间: 2019-11-22
摘要: Organic contaminants in agricultural soils are widely reported; however, their accumulation patterns are quite different among regions. This study reports the distribution, accumulation and risk assessment of polycyclic aromatic hydrocarbons (PAHs), dichlorodiphenyltrichloroethane (DDT) and hexachlorocyclohexane (HCH) in soils from the Corn Belt of northeast China at a regional scale. Concentrations of PAHs, DDT and HCH were306‐5300, 6.00–82.0 and 4.07–15.6 ng g⁻¹, respectively. Source analysis suggests PAHs were derived from regional combustion of biomass and coal, except where sites are strongly affected by local sources. The DDT and HCH residues in soils are likely derived from previous agricultural applications that have persisted due to slow microbiological degradation under low mean temperatures. Precipitation was only significantly correlated with PAH concentrations, suggesting that precipitation affected PAH but not DDT and HCH distributions at a regional scale. Positive correlations between DDT concentrations and total organic carbon (TOC) contents of soils suggest hydrophobic organic contaminants were associated with organic matter. In contrast, TOC contents were correlated with PAHs in alfisols but not in pedocals. Pedocals contained mainly high molecular weight PAHs, indicating that eluviation affected the accumulation of less hydrophobic organic contaminants. Different correlations between low molecular weight PAH and HCH concentrations with TOC contents were found in alfisols, suggesting that contaminant structure may also affect the accumulation of less hydrophobic organic contaminants in these soils. Risk analysis suggested that potential ecological risks related to soils in the Corn Belt may lead to reduced maize production and the potential for human health risks in the future.

25822. 题目: Role of cotton sticks biochar in immobilization of nickel under induced toxicity condition and growth indices of Trigonella corniculata L.
文章编号: N19112207
期刊: Environmental Science and Pollution Research
作者: Uzma Younis, Subhan Danish, Saeed Ahmad Malik, Niaz Ahmed, Tariq Muhammad Munir, Muhammad Khalid Rasheed
更新时间: 2019-11-22
摘要: Among various heavy metals, nickel (Ni) is a potential pollutant that accumulates in broad-leaf vegetables and is reported to be carcinogenic. Biochar (BC) is a nutrient-rich and effective organic amendment for immobilization of Ni in soil. Fenugreek (Trigonella corniculata L.), a broad-leaf vegetable, is commonly cultivated due to its all-inclusive composition of nutrients such as calcium and iron and β-carotene and vitamins. Therefore, a field-pot study was conducted to examine the effectiveness of cotton-sticks-waste biochar (BC) for soil immobilization of Ni in fenugreek crop cultivated between early-October to end-November 2015. Fenugreek was grown in a sandy-loam soil experimentally contaminated with various Ni levels (0, 25, 50, and 100 mg Ni kg⁻¹ soil) under three BC levels (0, 3, and 5%; w/w). Overall, results showed increasing plant lipid peroxidation (assessed via malondialdehyde) and ascorbic-acid concentration with increasing Ni toxicity level without BC application (p ≤ 0.05). Application of 3% BC increased the chlorophyll a (20.0%), chlorophyll b (49.1%), total chlorophyll (27.6%), carotenoids (21.6%), anthocyanin (27.2%), photosynthetic rate (112%), transpiration rate (45.0%), and sub-stomatal CO₂ concentration (19.9%) in fenugreek as compared to control (0% BC) under 50 mg Ni kg⁻¹ soil. Higher BC application rate (5%) was more effective in increasing the chlorophyll a (33.6%), chlorophyll b (81.1%), total chlorophyll (43.9%), carotenoids (71.7%), anthocyanin (77.8%), photosynthetic rate (127%), transpiration rate (42.2%), and sub-stomatal CO₂ concentration (23.5) over control under 100 mg Ni kg⁻¹ soil. We suggest that the consistent increases in dry mass, carbon flux rate and, protein, amino acids, and sugar contents of fenugreek (cultivated in a soil toxified with Ni and amended with 5% BC) seems to be caused by the reduction in the mobility of Ni in the presence of BC in a sandy-loam soil.

25823. 题目: Integrated production systems: An alternative to soil chemical quality restoration in the Cerrado-Amazon ecotone
文章编号: N19112206
期刊: CATENA
作者: Matheus B. Soares, Onã da S. Freddi, Eduardo da S. Matos, Renan F.R. Tavanti, Flávio J. Wruck, Joaquim P. de Lima, Vinicius Marchioro, Julio C. Franchini
更新时间: 2019-11-22
摘要: Soil organic carbon (SOC) is the main terrestrial carbon reservoir. The spatial distribution of SOC is mainly regulated by environmental factors and anthropogenic activity. Historically, land-use change has been responsible for much of the world’s greenhouse gas emissions. However, carbon storage can be improved through agricultural management, either by increasing carbon inputs through higher crop yields or by delaying the release of carbon into the atmosphere. Therefore, it is essential to correctly choose which cover crops to use and how long these crops will remain in the crop rotation system. In order to clarify these issues, the objective of this work was to evaluate the chemical quality and changes in soil carbon stock between no-tillage and soybean/corn crop succession systems and integrated crop-livestock systems. The study was carried out in Querência (MT), Brazil, located in the Cerrado/Amazon ecotone. The integrated systems were studied between 2007 and 2014. These systems followed annual crop rotation and forage rotation, and were laid out as a consortium or were isolated, with the aim of producing grain and meat. In order to determine soil chemical properties, 170 sampling plots were randomized among the treatments. The highest carbon values were observed in the integrated crop-livestock systems (ICL), probably due to higher inputs of organic residues. Crop rotation with plants of different families allowed better land use and soil exploration. However, integrated production systems comprising longer pasture periods, no-tillage, and soybean/corn crop succession decreased soil carbon. When comparing carbon stocks from 2010 to 2014, only integrated production systems ICL2 and ICL3 were able to increase carbon stocks. Our results highlight the importance of length of growing and correct choice of cover crops in maintaining SOC stocks, and thus provide insights to improve SOC stocks in agricultural land in Brazil's main producing region.

25824. 题目: Characterization for the transformation of dissolved organic matters during ultraviolet disinfection by differential absorbance spectroscopy
文章编号: N19112205
期刊: Chemosphere
作者: Hao Wu, Zhanghao Chen, Feng Sheng, Jingyi Ling, Xin Jin, Chao Wang, Cheng Gu
更新时间: 2019-11-22
摘要: The transformation of dissolved organic matter (DOM) during various disinfection processes has raised great concerns due to the generation of carcinogenic disinfection by-products (DBPs). Ultraviolet (UV) irradiation is an effective method for drinking water disinfection, during which DOM undergoes changes in functional groups and molecular weight. In this study, the spectrophotometric titration and gel permeation chromatography (GPC) determination were employed to investigate the changes in oxygenated groups and weight-averaged molecular weight (M_w) of two typical DOM during UV irradiation. The differential absorbance spectra (DAS) of DOM could be deconvoluted into six Gaussian bands. The change of relative band intensity was attributed to the change of oxygenated groups (carboxylic and phenolic groups), which was confirmed by combining DAS data and revised Non-Ideal Competitive Adsorption -Donnan model. The GPC result demonstrated that the M_w of DOM decreased after UV disinfection. Moreover, a linear correlation between M_w and the intensity of deconvoluted Gaussian band from DAS was established, which might be served as an alternative approach to estimate M_w and predict the hydrophobicity and DBPs formation potential of DOM in drinking water treatment and monitoring.
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25825. 题目: Molecular insight into variations of dissolved organic matters in leachates along China’s largest A/O-MBR-NF process to improve the removal efficiency
文章编号: N19112204
期刊: Chemosphere
作者: Hui Wang, Zhaowen Cheng, Zhiyi Sun, Nanwen Zhu, Haiping Yuan, Ziyang Lou, Xiaoliang Chen
更新时间: 2019-11-22
摘要: Dissolved organic matter (DOM) is a critical component of high-strength organic wastewater, and the study of them from molecular perspective could improve the removal efficiency. Leachate samples were collected from China’s largest two stage anaerobic/aerobic membrane bioreactor and nanofiltration (A/O-MBR-NF) process, with the treatment capacity of 5000 t/d, and characterized by electrospray ionization (ESI) coupled with Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) from molecular perspective. High molecular weight (m/z > 500) compounds with 40–50 carbon atoms and 15–20 double bond equivalence (DBE) were biodegraded into medium molecular weight compounds with 10–20 carbon atoms and ∼10 DBE. Contribution of lipids and unsaturated hydrocarbons compounds in DOM turned into 42.1% and 2.5%, respectively, while contribution of condensed aromatics in DOM dramatically increased to 15.4% in leachates along the A/O-MBR process. Most of DOM was converted into higher polymerization degree and accumulated in concentrated leachate (CL). Sulfur-containing compounds, whose relative peak ratio accounted for 56.4%, were regarded as recalcitrant DOM in CL. Increase of retention time in anaerobic unit for raw leachate might be useful for decomposing the long-chain organic compounds, which could also reduce loadings for the following A/O-MBR process. Well-focus techniques such as sulfur-oxidation bacteria could be introduced into the MBR unit for better removing organo-sulfur compounds. Advanced oxidation processes for CL degradation would be efficiency for the removal of recalcitrant DOM. Thus, leachate could be disposed in a zero-discharge way based on the practical experience of such a typical working treatment process.
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25826. 题目: Degradation kinetics of target compounds and correlations with spectral indices during UV/H₂O₂ post-treatment of biologically treated acrylonitrile wastewater
文章编号: N19112203
期刊: Chemosphere
作者: Xiang Tu, Xiaoyang Meng, Yang Pan, John C. Crittenden, Yaye Wang
更新时间: 2019-11-22
摘要: In this study, the post-treatment of biologically treated acrylonitrile wastewater was investigated during UV/H₂O₂ process. Five contaminants in the effluent were selected as target compounds, including Furmaronitrile (FMN), 3-Pyridinecarbonitrile (3PCN), 1,3-Dicyanobenzene (1,3-DCB), 5-Methyl-1H-benzotriazole (5MBT), and 7-Azaindole (7AID). Under optimal reaction conditions, the UV/H₂O₂ post-treatment exhibited good performances in destruction of organic compounds and toxicity. The photo-chemical parameters of the target compounds were measured and it was found that 5MBT and 3PCN had fast degradation rate constants under direct UV photolysis. The second-order rate constants of the target compounds with hydroxyl radicals were determined to be in the range of (1.0–5.0) × 10⁹ M⁻¹ s⁻¹ at pH 3.0 and 25 °C. A simplified pseudo-first-order steady state (Sim-PSS) model, which considered direct UV photolysis and radical oxidation simultaneously, agreed well with the experimental data from the post-treatment of a biologically treated effluent. High-performance size exclusion chromatography (HPSEC) coupled with diode-array detector (DAD) and fluorescence detector (FLD) analysis revealed that humic-like sub-peak signals from different molecular weights of fluorescent organic matter decreased consistently during the oxidation process, which made humic-like fluorescence exhibit higher correlation with the target compounds’ degradation than the spectral indices of UV absorbance at 254 nm (UVA₂₅₄) and protein-like fluorescence.

25827. 题目: Pyrogenic organic matter effects on soil bacterial community composition
文章编号: N19112202
期刊: Soil Biology and Biochemistry
作者: Jamie Woolet, Thea Whitman
更新时间: 2019-11-22
摘要: Pyrogenic organic matter (PyOM) is produced by the incomplete combustion of organic matter, and can represent a large portion of total soil organic carbon in both fire-affected systems and managed systems where PyOM is added intentionally as a soil amendment. The effects of PyOM on the structure of soil microbial communities remain a topic of fundamental interest, and a number of studies have begun to identify and characterize the PyOM-associated microbial community. However, it is unclear to what extent the effects of PyOM on soil bacteria are consistent. Our goals were to synthesize current related studies to (1) determine if there is a detectable and consistent “charosphere” community that characterizes PyOM-amended soils, (2) distinguish consistent responders at the phylum level to PyOM amendments, and (3) identify individual PyOM-responsive taxa that increase in relative abundance consistently across different soil types. We re-analyzed publicly available raw 16S Illumina sequencing data from studies that investigated the bacterial communities of PyOM-amended soils. We determined that soil source is more important than PyOM for shaping the trajectory of the community composition. Although we were able to identify a few genera that respond positively and somewhat consistently to PyOM amendments, including Nocardioides, Micromonospora, Ramlibacter, Noviherbaspirillum, and Mesorhizobium, in general, neither phylum-level nor genus-level responses to PyOM were consistent across soils and PyOM types. We offer suggestions for our future efforts to synthesize the effects PyOM may have on soil microbial communities in an array of different systems. Due to the dual challenges of high functional diversity at fine taxonomic scales in bacteria, and diverse ranges of soil and PyOM properties, researchers conducting future studies should be wary of reaching a premature consensus on PyOM effects on soil bacterial community composition. In addition, we emphasize the importance of focusing on effect sizes, their real-world meanings, and on cross-study effect consistency, as well as making data publicly available to enable syntheses such as this one.

25828. 题目: Methodology for selection of optical parameters as wastewater effluent organic matter surrogates
文章编号: N19112201
期刊: Water Research
作者: Sydney L. Ulliman, Julie A. Korak, Karl G. Linden, Fernando L. Rosario-Ortiz
更新时间: 2019-11-22
摘要: Absorbance- and fluorescence-based optical parameters are commonly used as surrogates in engineered systems, but there is no systematic approach for selecting robust parameters. This study develops a methodology that is applied to a case study of differentiating wastewater effluent organic matter from naturally-derived dissolved organic matter. The methodology defines criteria to identify optical parameters that could detect statistically significant compositional differences in organic matter, independent of organic matter concentration, and measure fluorescence-based parameters with low susceptibility to inner filter effects. The criteria were applied to 26 parameters that were measured for 11 pairs of source water and conventionally-treated wastewater samples collected from sites with varied spatial and temporal conditions. Only two parameters, apparent fluorescence quantum yield measured at excitation 370 nm and fluorescence peak ratio A:T, met the criteria across all sites. These results demonstrate and encourage an objective and robust process for selecting optical surrogates for organic matter characterization.
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25829. 题目: Organic Matter Amendment and Plant Colonization Drive Mineral Weathering, Organic Carbon Sequestration, and Water-Stable Aggregation in Magnetite Fe Ore Tailings
文章编号: N19112107
期刊: Environmental Science & Technology
作者: Songlin Wu, Yunjia Liu, Jeremy J. Bougoure, Gordon Southam, Ting-Shan Chan, Ying-Rui Lu, Shu-Chih Haw, Tuan Anh Huu Nguyen, Fang You, Longbin Huang
更新时间: 2019-11-21
摘要: The formation of water-stable aggregates in finely textured and polymineral magnetite Fe ore tailings is one of the critical processes in eco-engineering tailings into soil-like substrates as a new way to rehabilitate the tailings. Organic matter (OM) amendment and plant colonization are considered to be effective in enhancing water-stable aggregation, but the underlying mechanisms have not yet been elucidated. The present study aimed to characterize detailed changes in physicochemistry, Fe-bearing mineralogy, and organo-mineral interactions in magnetite Fe ore tailings subject to the combined treatments of OM amendment and plant colonization, by employing various microspectroscopic methods, including synchrotron-based X-ray absorption fine structure spectroscopy and nanoscale secondary ion mass spectroscopy. The results indicated that OM amendment and plant colonization neutralized the tailings' alkaline pH and facilitated water-stable aggregate formation. The resultant aggregates were consequences of ligand-promoted bioweathering of primary Fe-bearing minerals (mainly biotite-like minerals) and the formation of secondary Fe-rich mineral gels. Especially, the sequestration of OM (rich in carboxyl, aromatic, and/or carbonyl C) by Fe-rich minerals via ligand-exchange and/or hydrophobic interactions contributed to the aggregation. These findings have uncovered the processes and mechanisms of water-stable aggregate formation driven by OM amendment and plant colonization in alkaline Fe ore tailings, thus providing important basis for eco-engineered pedogenesis in the tailings.

25830. 题目: Structural Features and Pro-Inflammatory Effects of Water-Soluble Organic Matter in Inhalable Fine Urban Air Particles
文章编号: N19112106
期刊: Environmental Science & Technology
作者: Antoine Simões Almeida, Rita M. P. Ferreira, Artur M. S. Silva, Armando C. Duarte, Bruno M. Neves, Regina M. B. O. Duarte
更新时间: 2019-11-21
摘要: The impact of inhalable fine particulate matter (PM2.5, aerodynamic diameter <2.5 μm) on public health is of great concern worldwide. Knowledge on their harmful effects are mainly due to studies carried out with whole air particles, with the contribution of their different fractions remaining largely unknown. Herein, a set of urban PM2.5 samples were collected during daytime and nighttime periods in autumn and spring, aiming to address the seasonal and day-night variability of water-soluble organic matter (WSOM) composition. In vitro analysis of the oxidative and pro-inflammatory potential of WSOM samples was carried out in both acute (24 h) and chronic (3 weeks) exposure setups using Raw264.7 macrophages as cell model. Findings revealed that the structural composition of WSOM samples differs between seasons and in a day–night cycle. Cell exposure resulted in an increase in the transcription of the cytoprotective Hmox1 and pro-inflammatory genes Il1b and Nos2, leading to a moderate pro-inflammatory status. These macrophages showed an impaired capacity to subsequently respond to a strong pro-inflammatory stimulus such as bacterial lipopolysaccharide, which may implicate a compromised capacity to manage harmful pathogens. Further investigation on aerosol WSOM could help to constrain the mechanisms of WSOM-induced respiratory diseases and contribute to PM2.5 regulations.

25831. 题目: Effect of total solids content on anaerobic digestion of poultry litter with biochar
文章编号: N19112105
期刊: Journal of Environmental Management
作者: Mathu Indren, Cristian H. Birzer, Stephen P. Kidd, Paul R. Medwell
更新时间: 2019-11-21
摘要: Methane production via anaerobic digestion of poultry litter provides a pathway for energy production from an abundant waste product. Recent studies have shown the use of biochar (pyrolysed biomass) can decrease methane production lag times and increase peak daily yields from ammonia-stressed low-solids anaerobic digesters. Due to the variety of feedstocks and digester configurations used, research to date has not yet determined the effect of biochar addition as a function of the digester total solids content. This study shows the addition of biochar reduces the lag time by a greater percentage in the digesters with a higher total solids content. There was a 17%, 27% and 41% reduction lag time due to biochar addition at total solids contents of 5%, 10% and 20%, respectively. The peak daily methane yield increased by 136% at 10% total solids. There was no significant increase in the peak yield at 5% total solids, while there was a 46% increase at 20% total solids. Real-time PCR analysis confirms the Methanosaetaceae family, which is a key methanogen due to its ability to facilitate direct interspecies electron transfer while attached to biochar, preferentially attaches to biochar. Furthermore, this research shows the attachment of the Methanosaetaceae family, does not decrease with increasing total solids content. A potential negative effect of biochar addition, a reduced volumetric efficiency, can be negated by using a shorter retention time. This new understanding will help to improve predictions of the impact of biochar addition for new digester designs operating in semi-solids and high-solids conditions.

25832. 题目: Dissolved black carbon in throughfall and stemflow in a fire-managed longleaf pine woodland
文章编号: N19112104
期刊: Biogeochemistry
作者: Sasha Wagner, Steven Brantley, Stribling Stuber, John Van Stan, Ansley Whitetree, Aron Stubbins
更新时间: 2019-11-21
摘要: The interception of rainfall by trees enriches rainwater with tree-derived dissolved organic matter (tree-DOM), which represents the first terrigenous source of DOM during storm events. The tree-DOM is then exported from the canopy via rainfall that drips from leaves and branches (throughfall) or is funneled down the tree trunk (stemflow) to the forest floor. Here, we evaluate contributions of dissolved black carbon (DBC) to tree-DOM in fire-managed longleaf pine woodlands (Pinus palustris). These are the first quantitative measurements of throughfall and stemflow DBC for any type of forest or tree species. The inter-storm variability of tree-DOM concentrations, composition, and optical properties in throughfall and stemflow were also examined. Tree-DOM was enriched in dissolved organic carbon (DOC) and DBC compared to rainfall, and concentrations did not vary with storm size. Therefore, longleaf and slash pines contain a large repository of leachable organic matter that was not significantly diminished, even during large storm events. The aromaticity of stemflow DOM increased with amount of rainfall, suggesting bark may need to undergo a certain degree of saturation for the solubilization of DBC and other aromatic components. In tree-DOM, DBC comprised ~ 2% of DOC. A simple mass balance suggested annual yields of DBC in throughfall and stemflow (50–350 kg-DBC and 19 kg-DBC km⁻² year⁻¹, respectively). Therefore, atmospheric deposition would be enough to sustain a continual source of tree-derived DBC in longleaf pine ecosystems regularly maintained by fire.

25833. 题目: Priming effect intensity of soil organic carbon mineralization under no-till and residue retention
文章编号: N19112103
期刊: Applied Soil Ecology
作者: Zheng-Rong Kan, Ahmad Latif Virk, Gong Wu, Jian-Ying Qi, Shou-Tian Ma, Xing Wang, Xin Zhao, Rattan Lal, Hai-Lin Zhang
更新时间: 2019-11-21
摘要: No-till (NT) and residue retention (RR) are widely adopted techniques to improve soil health and mitigate global warming, but knowledge on the priming effect (PE) intensity of soil organic carbon (SOC) mineralization under NT and RR is still limited. Therefore, a field-cum-laboratory study was conducted to assess the effects of NT and RR as well as their interaction on the basal SOC mineralization and PE intensities. Soil samples obtained for 0–5, 5–10, and 10–20 cm layers, from a factorial experiment of tillage practices (NT and plow tillage (PT)) and residue managements (RR and residue removal (R0)), with and without ¹³C-labelled maize residues were incubated. The results showed that the contribution of PE intensity to total mineralization increased with the depth of soil layer, but the interaction of NT and RR on the PE was not significant. The PE of NT was lower than that of PT by 12.5–17.9% (30.6–54.3 mg kg⁻¹) under RR and 10.2–11.5% (32.4–39.9 mg kg⁻¹) under R0, because of higher soil water content and compaction under NT than that under PT. Additionally, the ∆POC (particulate organic carbon concentration loss) after incubation was the dominant positive factor; a lower ∆POC was observed under NT than that under PT. Moreover, the PE of RR was lower than that of R0 by 23.8–28.0% (66.7–96.7 mg kg⁻¹) under NT and 21.3–22.3% (68.5–81.6 mg kg⁻¹) under PT due to lower bulk density, higher SOC concentration before incubation, and substantial ∆DOC (dissolved organic carbon concentration loss, 7.7–25.8 mg kg⁻¹) under RR. Furthermore, the basal mineralization of NT was lower than that of PT under RR and R0. Although RR had higher basal mineralization than that under R0, the lowest basal mineralization per unit carbon was recorded in the NT with RR treatment due to a significant interaction between NT and RR. Therefore, a combination of NT and RR synchronously decreased the basal mineralization and PE intensity and enriched the amount of SOC, which can lead to positive feedback against the SOC sequestration.

25834. 题目: Preservation of organic carbon promoted by iron redox transformation in a rice-wheat cropping system
文章编号: N19112102
期刊: Applied Soil Ecology
作者: Xiaolei Huang, Wenjing Kang, Lei Wang, Guanghui Yu, Wei Ran, Jianping Hong, Qirong Shen
更新时间: 2019-11-21
摘要: Mineral protection regulates long-term global preservation of soil organic carbon (SOC), but little research has been conducted on the iron (Fe) oxide availability for carbon binding regulated by seasonal variation of wetting and drying and fertilization in paddy soils. The objective of this study was to explore the effects of five-year rice-wheat rotation and organic fertilization on the production of short-range-ordered (SRO) Fe oxides and SOC sequestration. Five fertilization treatments were examined: (1) no fertilizer control (CK), (2) chemical nitrogen, phosphorus and potassium (NPK), (3) 50% NPK plus manure (NPKM), (4) 100% NPK plus straw (NPKS), and (5) 30% NPK plus manure organic-inorganic compound fertilizer (NPKMOI). Soil samples were collected from 2013 to 2015 after each wheat and rice harvest. A split-plot analysis of variation was used to investigate the respective role of fertilizer treatments (main-plot) and crop seasons (sub-plot) in the transformation of SRO-Fe oxides. Variation partitioning analysis was used to quantify the contribution of SRO-Fe oxides to the accumulation of SOC. Five-year rice-wheat rotation without any fertilization (CK) increased the oxalate extractable Fe oxides (Feo) by 55.06% compared with the initial soil. The Feo concentration was higher (P < 0.05) in the NPKM, NPKS and NPKMOI treatments than in the NPK and CK treatments, and was higher after the rice harvest than after the wheat harvest. Furthermore, the Feo concentration was positively (P < 0.001) correlated with the SOC content and negatively correlated with the specific carbon mineralization rate (SCMR, rate per unit SOC). Moreover, the Feo could explain 52.57% and 40.5% of the variation in the SOC content and the SCMR, respectively. In addition, the partial humification coefficient (PHC, the percentage of SOC change per unit of exogenous carbon input) of the crop straw was 12.92% but amounted to 41.45% to 46.35% for different types of compost. These results indicate that the reductive dissolution and subsequent oxidative precipitation of Fe oxides induced by seasonal alternation of wetting and drying can be further promoted via organic fertilization possibly by forming organo-Fe complexes, which contribute to the accumulation of SRO-Fe oxides and the preservation of organic carbon in paddy soils.
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25835. 题目: Precipitation of protodolomite facilitated by sulfate-reducing bacteria: The role of capsule extracellular polymeric substances
文章编号: N19112101
期刊: Chemical Geology
作者: Deng Liu, Qigao Fan, Dominic Papineau, Na Yu, Yueying Chu, Hongmei Wang, Xuan Qiu, Xingjie Wang
更新时间: 2019-11-21
摘要: The origin of dolomite has long puzzled geologists. It has recently been documented that sulfate-reducing bacteria (SRB) are capable of catalyzing the formation of protodolomite, a previously proposed precursor of ordered sedimentary dolomite. However, the catalytic mechanism of SRB remains incompletely understood. This experimental study is aimed at probing the effect of capsule extracellular polymeric substances (capsule EPS) from SRB on the crystallization of protodolomite in vivo. The capsule EPS tested herein was isolated from a protodolomite-mediating SRB, Desulfotomaculum ruminis, and added into a solution wherein the degree of oversaturation was close to the growth medium of D. ruminis at stationary phase. The solid products were characterized with X-ray diffraction (XRD), Raman spectroscopy and, scanning and transmission electron microscopy (SEM and TEM). Our results indicated that aragonite emerged in the reactors without capsule EPS, while Ca-Mg carbonates (Mg-calcite and protodolomite) were produced in the systems amended with capsule EPS. The incorporation amount of Mg²⁺ in Ca-Mg carbonates was enhanced with the increasing concentration of capsule EPS. The predominant occurrence of protodolomite was found in the reactor with 140 mg/L capsule EPS. These resulting protodolomites were spherical in shape, and composed of numerous nano-particles. The catalytic influence of capsule EPS on the precipitation of protodolomite might be attributed to their strong Mg²⁺ binding capacity, potentially diminishing Mg-hydration, which is a potent inhibitor of protodolomite crystallization. The results of Fourier transformation infrared (FT-IR) spectra showed that Mg²⁺ was bonded with carboxyl and hydroxyl groups on capsule EPS. This inferred adsorption capacity of capsule EPS was also supported by new calculations of complexation chemistry between Mg-H₂O complex and organic compounds present in capsule EPS.

25836. 题目: Characteristics, speciation, and bioavailability of mercury and methylmercury impacted by an abandoned coal gangue in southwestern China
文章编号: N19112010
期刊: Environmental Science and Pollution Research
作者: Longchao Liang, Xiaohang Xu, Jialiang Han, Zhidong Xu, Pan Wu, Jianyang Guo, Guangle Qiu
更新时间: 2019-11-20
摘要: During coal mining activities, a lot of coal gangue is produced, which usually contains high mercury (Hg) concentrations as well as the acid mine drainage (AMD) generator of pyrite. In the present study, the total mercury (THg) and methylmercury (MeHg) in gangue, water, sediment, paddy soil, and rice samples, collected from abandoned coal mining areas, were analyzed. Results showed that the THg concentrations ranged from 0.37 to 35 mg/kg (11 ± 8.4 mg/kg) and 0.15 to 19 mg/kg (2.0 ± 3.9 mg/kg) in gangue and sediments, respectively. For paddy soils, the THg concentrations and MeHg varied from 0.16 to 0.91 mg/kg and 0.71 to 11 ng/g, respectively. Rice samples exhibited wide concentration ranges of THg (3.0–22 ng/g) and MeHg (0.71–8.9 ng/g). Sequential extraction of Hg revealed that the nitric acid-extractable state Hg (F4) was the dominant Hg species in gangue and sediment, while humic acids state Hg (F3) was the dominant form in paddy soil. Compared with gangue, higher percentages of F3 and the residual state Hg (F5) in both sediment and soil samples implied the transformation of F4 to F3 and F5 during transportation. Soil n-HAs (the difference between the total organic carbon and humic acids) were positively correlated with both THg and MeHg in soil and rice, indicating that n-HAs enhance Hg bioavailability under acidic conditions. Further studies should be conducted to reveal the factors influencing the transformation of different Hg fractions, providing ideas on decreasing the bioavailability of Hg in coal mining areas.

25837. 题目: Effect of biochar and wood ash amendment on biochemical methane production of wastewater sludge from a temperature phase anaerobic digestion process
文章编号: N19112009
期刊: Bioresource Technology
作者: Caroline Cimon, Paul Kadota, Cigdem Eskicioglu
更新时间: 2019-11-20
摘要: Biochemical methane production (BMP) assays of acidified municipal sludge were conducted with local char (biochar and wood ash) in granular (0.85-4.75 mm) and powdered (< 0.075 mm) form. The effects of char addition on BMP were investigated under high acid stress conditions at substrate to inoculum ratios of 2.2, 3.2 and 4.4 g volatile solids (VS)/g-VS and char dosages of 0.2–3.7 g/g-VS_substrate. Powdered biochar at dosage of 0.8-3.7 g/g-VS_substrate achieved the highest improvement in rate of methane production with 192-461% increase from controls, in the first 16 days. This increase was followed by an early stationary methane production phase and a reduction of total methane yield by up to 25%. Results indicated that the early plateau could be caused by adsorption of volatile fatty acids by the biochar.

25838. 题目: Organic geochemical signals of controlling freshwater dynamics on salinity stratification in organic-rich shales in the Lower Permian Irati Formation (Paraná Basin, Brazil)
文章编号: N19112008
期刊: Organic Geochemistry
作者: Laercio Lopes Martins, Hans-Martin Schulz, Hélio Jorge Portugal Severiano Ribeiro, Caroline Adolphsson do Nascimento, Eliane Soares de Souza, Georgiana Feitosa da Cruz
更新时间: 2019-11-20
摘要: The Lower Permian Irati Formation in the northeastern and central eastern Paraná Basin (southern Brazil) was investigated in terms of bulk and molecular organic geochemistry in order to enlighten the complex depositional paleoenvironment during deposition of Irati black shales. The geochemical data reflect temporal and spatial variations of freshwater incursions promoting salinity stratification and high primary productivity in surface waters with the establishment of photic zone euxinia. Overall, highly concentrated C₁₇ long-chain alkylnaphthalenes point to algal blooms as a result of freshwater inflows into the Irati Sea, mostly in the central eastern basin segment, and resemble concentration variations of pristane, phytane and nC₁₇. The freshwater inflows were also retraced by increasing chroman ratios toward the top of the investigated units along with the general decrease of further palaeosalinity indicators, e.g., gammacerane, tetracyclic (C₂₄), β-carotane, and the herein suggested γ-carotane and lexane indexes. The existence of a water column stratification promoting organic matter preservation is supported by the detection of tetrahydrophenanthrene at high concentrations, in addition to the known prominent occurrence of gammacerane. The detection of C₁₀ to C₃₁ aryl isoprenoids in addition to C₁₆ and C₁₈ pseudohomologue aryl isoprenoids points to the presence of photic zone euxinia. In general, samples from the central eastern basin were deposited in a deeper marine setting with lower salinity than samples from the northeastern basin, which displays signals of a shallower marine environment with reducing bottom water conditions, both deposited under freshwater influxes.

25839. 题目: The effects of straw incorporation with plastic film mulch on soil properties and bacterial community structure on the Loess Plateau
文章编号: N19112007
期刊: European Journal of Soil Science
作者: Yüze Li, Yingchun Hu, Duanpu Song, Shihan Liang, Xiaoliang Qin, Kadambot H. M. Siddique
更新时间: 2019-11-20
摘要: The application of plastic film mulch and the return and incorporation of crop straw into topsoil as independent treatments affect soil physicochemical properties, including nutrient balance/cycling. It remains unclear whether combining straw incorporation and plastic film mulch significantly affect soil physicochemical properties and bacterial communities. We conducted a two‐factor (plastic film mulch application and maize straw incorporation) randomised block design experiment with four treatments: no plastic film mulch or straw incorporation (C), plastic film mulch (M), straw incorporation without mulch (CS) and straw incorporation with mulch (MS). Soil was sampled at the end of the growing cycle after three years of treatment. Soil organic carbon (SOC), total nitrogen (TN) and nitrate‐nitrogen (NO₃^–‐N) concentrations significantly improved after straw incorporation. Plastic film mulch had a significant negative effect on soil bacterial richness, while straw incorporation had no effect. Straw incorporation had a significant positive effect on bacterial diversity, while plastic film mulch had no effect. The MS and M treatments had significantly more Proteobacteria than the C and CS treatments. Formation of the soil bacterial community structure was driven by soil TN, NO₃^–‐N and SOC in the treatments with straw incorporation, and soil ammonium‐nitrogen (NH₄⁺‐N) in the treatments without straw incorporation. In conclusion, plastic film mulch coupled with straw incorporation can significantly change the taxonomical and functional composition of soil bacterial communities and enhance soil bacterial diversity by affecting carbon and nitrogen cycling in cropland soils of farmland, especially in arid and semi‐arid regions.

25840. 题目: Straw and optimized nitrogen fertilizer decreases phosphorus leaching risks in a long-term greenhouse soil
文章编号: N19112006
期刊: Journal of Soils and Sediments
作者: Chao Fei, Shirong Zhang, Wenliang Wei, Bin Liang, Junliang Li, Xiaodong Ding
更新时间: 2019-11-20
摘要: Purpose: Phosphorus (P) mobility in soil is controlled by its forms and soil sorption capacity. The P forms and soil sorption capacity are both affected by nitrogen (N) and carbon (C) addition. This paper aimed to (i) analyze effects of N and straw application on the different forms and content of P in the soil and its leachates in greenhouse soil, and (ii) explain variations in soil P transformation and transport in terms of contributing soil factors. Material and methods: In this study, the impacts of N and straw application on the transformation and transport of soil P were investigated after 17 years in a greenhouse. Four fertilization regimes were implemented: farmer standard fertilization practice (CK), straw incorporation treatment (SC), optimized N fertilizer application (ON), and combined straw and optimized N fertilizer application (SN). P forms and its contents were determined in the selected leached water and its related soil samples. Results and discussion: Compared with CK, ON treatment significantly (p < 0.05) decreased total phosphorus (P_t) and the proportion of organic phosphorus (P_o) in soil, while straw amendment did not affect soil P_t content. SC, ON, and SN all decreased soil available phosphorus (P_a) but enhanced P transformation, as evidenced by the increase in the ratio of P_a to P_t and microbial phosphorus (MBP) and alkaline phosphatases (ALP) in soil. After SN implementation, soil P adsorption capacity increased significantly and was associated with higher soil organic matter (SOM) and CaCO₃. ON showed lower P_t in the leachate than CK, but SC did not lead to significantly different. Under the SN regime, P_t loss by leaching decreased by 29.4% compared with CK and significantly reduced proportion of total dissolve P (DP_t) in leachate. Conclusions: Our study highlights that straw and optimized N fertilizer in SN treatment not only generates lower P loss by leaching but also promotes the transformation of soil P, which were attributed to higher soil P_a in greenhouse soil. This finding further indicates that P transformation and transport in the different fertilizer regimes was primarily linked to pH and SOM in greenhouse soil.