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25341. 题目: Anthropogenic influences on mercury in Chinese soil and sediment revealed by relationships with total organic carbon
文章编号: N19091304
期刊: Environmental Pollution
作者: Wen Xue, Sae Yun Kwon, Stephan E. Grasby, Elsie M. Sunderland, Xin Pan, Ruiyang Sun, Ting Zhou, Haiyu Yan, Runsheng Yin
更新时间: 2019-09-13
摘要: Rapid industrialization has led to high levels of mercury (Hg) releases from anthropogenic sources in China. When deposited to terrestrial ecosystems, Hg has a high affinity for natural organic carbon. This means that Hg concentrations will vary naturally as a function of the total organic carbon (TOC) content of different soils and sediment. Thus, Hg to TOC ratios in topsoil and surface sediment provides a useful normalized tracer of the anthropogenic impact on Hg contamination. We compiled literature-documented Hg and total organic carbon (TOC) data for topsoil (n = 957) and surface sediment (n = 1142) in China. Topsoil samples (n = 100) were also collected in this study to broaden the spatial coverage. We found large differences in Hg:TOC ratios among topsoil from background sites, agricultural and urban areas, and mining sites and surface sediment from fluvial, coastal, and marine environments. Specifically, a significant increase in Hg:TOC ratios occurred between soils from background sites (median: Hg:TOC = 21.1; Inter-Quartile Range (IQR): 9.67 to 40.7) and agricultural areas (median: 34.1; IQR: 22.1 to 58.7), urban areas (median: 62.1 ng g⁻¹; IQR: 34.2 to 154) and mining sites (median: 2780; range: 181 to 43500). Urban and mining sites show the largest increase in Hg:TOC ratios, reflecting elevated anthropogenic Hg inputs in these areas. Fluvial sediment showed higher Hg:TOC ratios (median: 197; IQR: 109 to 389) than coastal (median: 88.3; IQR: 46.8 to 168) and marine sediment (median: 89.7; IQR: 53 to 138), indicating decreased anthropogenic Hg input from rivers to coastal and marine regions. Results of our study suggest Hg:TOC ratios are a useful normalized indicator of the influence of anthropogenic Hg releases on Hg enrichment in topsoil and surface sediment.
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25342. 题目: Oxygen-rich biochar from torrefaction: A versatile adsorbent for water pollution control
文章编号: N19091303
期刊: Bioresource Technology
作者: Liang Li, Mei Yang, Qian Lu, Wenkun Zhu, Hanqing Ma, Lichun Dai
更新时间: 2019-09-13
摘要: Compared to pyrochar (PC), little is known about the capability of torrefaction char (TC) in water pollution control. In this study, the physicochemical properties of TC and PC, and their adsorption performances for uranium (U(VI)) and methylene blue (MB) were investigated. Results showed that TC was higher in oxygen content, and richer in oxygen-containing functional groups. The maximum U(VI) and MB adsorption capacities were increased from 56.21 and 192.67 mg/g for PC, respectively, to > 100 and > 350 mg/g for TC, respectively, indicating that TC was much more efficient than PC. Furthermore, torrefaction atmosphere affected the adsorption performance of resulting TC. For example, TC from N₂ was more efficient in MB adsorption, while TC from air was more efficient in U(VI) adsorption. Thus, attributed to the lower processing temperature, simpler preparation route, and higher adsorption capacity, TC could be a competent candidate for water pollution control.
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25343. 题目: Influence of mineral water constituents, organic matter and water matrices on the performance of the H2O2/IO4−-advanced oxidation process
文章编号: N19091302
期刊: Environmental Science: Water Research & Technology
作者: Nor Elhouda Chadi, Slimane Merouani, Oualid Hamdaoui, Mohammed Bouhelassa, Muthupandian Ashokkumar
更新时间: 2019-09-13
摘要: We have recently reported that the reaction of H₂O₂/IO₄⁻ could be a new advanced oxidation process (AOP) for water treatment [N. E. Chadi, S. Merouani, O. Hamdaoui, M. Bouhelassa and M. Ashokkumar, H₂O₂/periodate (IO₄⁻): a novel advanced oxidation technology for the degradation of refractory organic pollutants, Environ. Sci.: Water Res. Technol., 2019, 5, 1113–1123]. Experiments were conducted in deionized water using toluidine blue (TB) as a model pollutant, in which the impact of all operating conditions was clarified. Herein, we report, for the first time, the impact of mineral water constituents (salts), different kinds of organic additives (surfactants, sucrose, glucose and carboxylic acids) and water matrices (natural mineral water, seawater and treated wastewater effluent) on the performance of this emerging AOP. It was observed that the presence of salts decreased the degradation efficiency of the process. The one exception is that of bicarbonate which notably accelerated the TB degradation rate but only at low HCO₃⁻ concentration. Similarly, the presence of organic competitors diminished the efficiency of TB degradation through consuming radicals and oxidizing species generated by the reaction of H₂O₂ with periodate. The quenching impact of organic competitors and salts increased with their concentrations in the solution. Degradation trials conducted in real environmental matrices showed that more than 50% of the process efficacy was lost when the pH of the matrices was adjusted to 5.4, but a lower loss was observed when the process was operated at natural pH (∼7.6). All these findings were discussed and interpreted with regard to the reactivity of radicals formed with additives present in the system.
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25344. 题目: Simultaneous in-situ remediation and fertilization of Cd-contaminated weak-alkaline farmland for wheat production
文章编号: N19091301
期刊: Journal of Environmental Management
作者: Juan Li, Panyue Zhang, Junpei Ye, Guangming Zhang, Yajing Cai
更新时间: 2019-09-13
摘要: In-situ remediation of heavy metal-contaminated farmland mainly focuses on acidic soil, however, weak-alkaline farmland widely exists in north China. Meanwhile, fertilization is usually ignored, but it may influence remediation efficiency as well as grain production. In this paper, field experiments were carried out to investigate in-situ simultaneous remediation and fertilization of Cd-contaminated weak-alkaline soil by microbial agent mixed with fulvic acid (MFA), wheat straw biochar, sepiolite and their mixture. Results showed that addition of these conditioners decreased the soil available Cd by 39.86%–71.33% and the wheat Cd by 41.94%–87.10%. The decrease order of soil available Cd followed sepiolite > mixture > biochar > MFA, while the decrease order of wheat Cd was mixture > sepiolite > biochar > MFA. With addition of mixture, the wheat Cd reduced to 0.08 mg/kg, lower than the Cd limit of 0.1 mg/kg in Contaminant Limit in Food of National Food Safety Standards (GB2762-2017), and the highest wheat yield reached 7590 kg/hm². The MFA had significant effects on improvement of soil organic matters, nutrients and rhizosphere microbes; the biochar was prominent in improving soil organic matters, inhibiting wheat Cd and soil available Cd; the sepiolite had obvious advantages in reducing wheat Cd and soil available Cd; and the mixture had a more balanced effect on soil remediation and fertilization. Correlation study showed that soil available Cd significantly affected the uptake of Cd by wheat, and wheat yield was significantly positively correlated with soil organic matters, available N. Therefore, reducing soil available Cd, increasing soil organic matters and nutrients are the keys to simultaneous remediation and fertilization of Cd-contaminated weak-alkaline soil for wheat production.
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25345. 题目: Size‐resolved characterization of the chromophores in atmospheric particulate matter from a typical coal‐burning city in China
文章编号: N19091214
期刊: Journal of Geophysical Research: Atmospheres
作者: Qingcai Chen, Zhen Mu, Wenhuai Song, Yuqin Wang, Zhaohong Yang, Lixin Zhang, Yan‐Lin Zhang
更新时间: 2019-09-12
摘要: This study reports the size‐resolved characterization of the chromophores in atmospheric particulate matter in Linfen, a typical coal‐burning city in China. The optical properties of both the water‐soluble and water‐insoluble chromophores in atmospheric particulates are studied using excitation‐emission matrix (EEM) spectroscopy and follow the parallel factor (PARAFAC) analysis of EEM data. The mass absorption efficiency (MAE) and normalized fluorescence volume (NFV) by mass concentration of the organic carbon in methanol‐soluble matter (MSM) in the particulate samples are stronger than that of the water‐soluble matter (WSM). We found that the total absorption (Abs), fluorescence volume (FV), MAE and NFV of particle extracts with sizes less than 10 μm increased with the decreasing particle size. The total concentration of the selected seven polycyclic aromatic hydrocarbons (PAHs) was positively correlated with the Abs365 and FV of both the WSM and MSM, but the average contribution of the selected PAHs to the total Abs and FV was very small (<3%). This study is the first to report a size‐resolved characterization of the chromophores in atmospheric particulate matter. Humic‐like substances tend to be present in small particles, and tryptophan‐like and tyrosine‐like components tend to increase with increasing particle size.

25346. 题目: Molecular-Scale Investigations Reveal Noncovalent Bonding Underlying the Adsorption of Environmental DNA on Mica
文章编号: N19091213
期刊: Environmental Science & Technology
作者: Hang Zhai, Lijun Wang, Christine V Putnis
更新时间: 2019-09-12
摘要: Mineral–soil organic matter (SOM including DNA, proteins, and polysaccharides) associations formed through various interactions, play a key role in regulating long-term SOM preservation. The mechanisms underlying DNA–mineral and DNA–protein/polysaccharide interactions at nanometer and molecular scales in environmentally relevant solutions remain uncertain. Here, we present a model mineral–SOM system consisting of mineral (mica)–nucleic acid (environmental DNA, eDNA)/protein (bovine serum albumin)/polysaccharide (alginate), and combine atomic force microscopy (AFM)-based dynamic force spectroscopy and PeakForce quantitative nanomechanical mapping using DNA-decorated tips. Single-molecule binding and adhesion force of eDNA to mineral and to mineral adsorbed by protein/polysaccharide reveal the noncovalent bonds and that systematically changing ion compositions, ionic strength, and pH result in significant differences in organic–organic and organic–mineral binding energies. Consistent with the bond-strength measurements, protein, rather than polysaccharide, promotes mineral-bound DNA molecules by ex situ AFM deposition observations in relatively high concentrations of divalent cation-containing acidic solutions. These molecular-scale determinations and nanoscale observations should substantially improve our understanding of how environmental factors influence the organic–mineral interfacial interactions through the synergy of collective noncovalent and/or covalent bonds in mineral–organic associations.

25347. 题目: New insights into the variation of dissolved organic matter components in different latitudinal lakes of northeast China
文章编号: N19091212
期刊: Limnology and Oceanography
作者: Longji Zhu, Yue Zhao, Sicong Bai, Haixuan Zhou, Xiaomeng Chen, Zimin Wei
更新时间: 2019-09-12
摘要: Dissolved organic matter (DOM) plays a key role in the carbon cycle of freshwater ecosystems. We explored DOM composition from six lakes encompassing a typical latitudinal gradient of lakes in northeast of China (41.9°N–48.6°N). Generally, the relative contents of protein‐like components decreased while humic‐like components increased with increasing latitude. Additionally, the results from modified two‐dimensional correlation spectroscopy indicated that humic‐like components with relatively simple structure were formed earlier than those with relatively complex structure. Furthermore, structural equation models suggested that at higher latitude, lake DOM tended to stabilize as protein‐like component was transformed into humic‐like component. We also found that nutrients (e.g., nitrogen and phosphorus) were key factors affecting DOM composition in low‐latitudinal lakes, whereas temperature was the key factor affecting DOM composition in high‐latitudinal lakes. In conclusion, this study identified the factors which explained the observed latitudinal pattern of DOM in northeast lakes of China. This study provided a theoretical basis for DOM management of lakes at different latitudes.

25348. 题目: Eukaryotic influence on the oceanic biological carbon pump in the Scotia Sea as revealed by 18S rRNA gene sequencing of suspended and sinking particles
文章编号: N19091211
期刊: Limnology and Oceanography
作者: Manon T. Duret, Richard S. Lampitt, Phyllis Lam
更新时间: 2019-09-12
摘要: Suspended marine particles constitute most of the particulate organic matter pool in the oceans, thereby providing substantial substrates for heterotrophs, especially in the mesopelagic. Conversely, sinking particles are major contributors to carbon fluxes defining the strength of the biological carbon pump (BCP). This study is the first to investigate the differential influence of eukaryotic communities to suspended and sinking particles, using 18S rRNA gene sequencing on particles collected with a marine snow catcher in the mixed layer and upper mesopelagic of the Scotia Sea, Southern Ocean. In the upper mesopelagic, most eukaryotic phytoplankton sequences belonged to chain‐forming diatoms in sinking particles and to prymnesiophytes in suspended particles. This suggests that diatom‐enriched particles are more efficient in carbon transfer to the upper mesopelagic than those enriched in prymnesiophytes in the Scotia Sea, the latter more easily disintegrating into suspended particles. In the upper mesopelagic, copepods appeared most influential on sinking particles whereas soft‐tissue metazoan sequences contributed more to suspended particles. Heterotrophic protists and fungi communities were distinct between mixed layer and upper mesopelagic, implying that few protists ride along sinking particles. Furthermore, differences between predatory flagellates and radiolarians between suspended and sinking particles implied different ecological conditions between the two particles pools, and roles in the BCP. Molecular analyses of sinking and suspended particles constitute powerful diagnostic tools to study the eukaryotic influence on the BCP in a more holistic manner compared to classic carbon export studies focusing on sinking particles.

25349. 题目: Terrestrial-marine continuum of sedimentary natural organic matter in a mid-latitude estuarine system
文章编号: N19091210
期刊: Journal of Soils and Sediments
作者: Carlo Bravo, Christian Millo, Stefano Covelli, Marco Contin, Maria De Nobili
更新时间: 2019-09-12
摘要: Purpose: Humic acids (HA) have several environmental roles, but are particularly important in aquatic environments, being recognized as redox active natural organic matter (NOM) components. We examined NOM in recent sediments of a low-energy coastal environment which is free from inputs of dissolved terrestrial HA as their solubility is suppressed by bonding with Ca²⁺ ions. Our aim is to investigate the contribution of autochthonous versus terrestrial C sources to HA and their fractions along a river-coastal lagoon transect. Materials and methods: Surface sediments were collected along the Aussa River (R), in the central basin of the Marano and Grado Lagoon (L) and within a secluded lagoon fish farm (FF). Extractable NOM components were obtained by extracting sediments first with 0.5 M NaOH (free NOM) and then with 0.1 M NaOH plus 0.1 M Na₄P₂O₇ (bound NOM). Extracts were separated into non-humic and humic fractions by solid phase chromatography. Organic carbon (C_org), total nitrogen (N_tot), δ¹³C, and δ¹⁵N were determined with an Isotope Ratio Mass Spectrometer (Thermo Scientific Delta V Advantage) coupled with an Elemental Analyzer (Costech Instruments Elemental Combustion System). Fourier-transform infrared (FTIR) spectra were recorded with a FT-IR100 PerkinElmer Spectrometer. UV-vis spectra were recorded at pH 7 by a Varian Cary Spectrophotometer. Results and discussion: Both NOM and HA display typical traits of terrestrial origin in river sediments and of a more marine (algal) origin in lagoon and fish farm sediments. This trend is evident in free HA, whereas bound HA seem more influenced by terrestrial inputs. A larger proportion (60–70%) of non-humic C was extracted by NaOH in all samples. Bound HA differ from free HA for their C/N ratios, which are higher and vary within a much narrower range. The changes in HA’s ¹³C isotopic composition, FTIR spectra, and spectroscopic parameters (SUVA₂₅₄, S_R, and aromaticity) highlight a progressive mixing of terrestrial and marine substrates that either undergo in situ humification or are transported as materials sorbed onto suspended mineral particles. Conclusions: Our results highlight the existence of a complex, but continuous pattern of terrestrial and marine contributions to C sequestration and humification even in transitional environments where allochthonous humic C inputs are restricted due to insolubilization of humic substances by Ca²⁺. Along the examined transect, the NOM and free and bound HA appear well differentiated. Terrestrial inputs contribute to the bound HA fraction via transported mineral particles in all the samples, no matter the environment encountered.

25350. 题目: Preparation and characterization of alginate-kelp biochar composite hydrogel bead for dye removal
文章编号: N19091209
期刊: Environmental Science and Pollution Research
作者: Godfred Ohemeng-Boahen, Divine Damertey Sewu, Seung Han Woo
更新时间: 2019-09-12
摘要: The alginate-kelp biochar composite hydrogel bead (Alg-KBC) was successfully developed via physical crosslinking with Ca²⁺. The composite material was characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR), inductively coupled plasma optical emission spectrometry (ICP-OES), and elemental analyzer. The Alg-KBC showed high removal capacity for crystal violet (CV), from aqueous solution (33.8% more than that of the pristine alginate bead). The adsorption isotherm data were fitted to the nonlinear forms of the Langmuir, Freundlich, and Redlich-Peterson isotherm models. Also, the adsorption kinetics data were analyzed with the nonlinear forms of the pseudo-first-order, pseudo-second-order, and intra-particle diffusion models. Both chemisorption and physisorption with an indispensable role of external mass transfer and stagewise pore diffusion were essential in the adsorption process. Thus, by impregnating biochar powder in alginate, a bio-platform, a composite hydrogel bead which has higher affinity for cationic dye in aqueous medium and also eliminates the onerous task of separating biochar powder from the adsorbate solution, was obtained. Hence, the Alg-KBC can be considered for efficient dye removal in the wastewater treatment process.

25351. 题目: pH-responsive lignin-based magnetic nanoparticles for recovery of cellulase
文章编号: N19091208
期刊: Bioresource Technology
作者: Rui-jing Dong, Da-feng Zheng, Dong-jie Yang, Xue-qing Qiu
更新时间: 2019-09-12
摘要: Enzymatic hydrolysis of lignocellulose to produce bioethanol by cellulase is an important method to alleviate the energy crisis. In this paper, in order to overcome the shortcomings of low efficiency, high cost and easy deactivation of cellulase in the process of bio-refinery, pH-responsive lignin-based magnetic nanoparticles (Fe₃O₄/LSQA) were synthesized to immobilize and recover cellulase. It was shown that a high immobilization ratio of 55.52 % for cellulase was obtained. Meanwhile, the desorption ratio was 68.27% by adjusting the pH of the system. After five reusing cycles, the desorbed cellulase retained 31.79% of the relative activity due to the pH responsiveness of Fe₃O₄/LSQA. These results not only provide a new idea for the recycling of cellulase, but also broaden the application of industrial lignin and increase the extra value.
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25352. 题目: Enhanced butanol-hydrogen coproduction by Clostridium beijerinckii with biochar as cell’s carrier
文章编号: N19091207
期刊: Bioresource Technology
作者: Jiwen Wu, Lili Dong, Chunshuang Zhou, Bingfeng Liu, Defeng Xing, Liping Feng, Xiukun Wu, Qi Wang, Guangli Cao
更新时间: 2019-09-12
摘要: In this study, the effects of biochar on the fermentation performance of butanol-hydrogen coproduction by Clostridium beijerinckii F-6 were investigated. Results showed that the biochar with rich porous and graphitized structure can significantly promote the coproduction of butanol and hydrogen. The productivity of butanol and hydrogen reached 0.148 g/L/h and 0.299 mmol/L/h with biochar addition which were 20.23% and 48.76% higher than that in control without biochar addition, respectively. Moreover, the whole energy conversion efficiency calculated based on the heat value showed increment from 43.69% to 51.75% with biochar addition. Combined analysis of organic acids accumulation and oxidation-reduction potential fluctuation proved that biochar can regulate reducing power during fermentation and accelerate the conversion of acid phase to solvent phase. Scanning electron microscope images showed that biochar acted as carriers for cells absorption. Confirmation experiment further proved that biochar enhanced the butanol tolerant ability of Clostridium beijerinckii F-6.
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25353. 题目: Wodyetia bifurcata biochar for methylene blue removal from aqueous matrix
文章编号: N19091206
期刊: Bioresource Technology
作者: Kleber Jean Leite dos Santos, Grazielle Emanuella de Souza dos Santos, Ícaro Mychel Gomes Leite de Sá, Alessandra Honjo Ide, José Leandro da Silva Duarte, Sandra Helena Vieira de Carvalho, João Inácio Soletti, Lucas Meili
更新时间: 2019-09-12
摘要: The endocarp of Wodyetia bifurcata was used to produce biochar by vacuum pyrolysis as an alternative adsorbent for methylene blue (MB) removal. The influence of different pyrolysis temperatures, particle diameters and activation agents in the adsorption process was studied. Kinetics and adsorption equilibrium were also evaluated. Biochar obtained at higher pyrolysis temperatures and activated with H₃PO₄ showed the best adsorptive capacities, achieving 83% of MB removal. The experimental data fitted better with pseudo-second order model. Isotherms performed at 25, 40, 50 and 60 °C showed that the adsorption of MB onto the activated biochar had no concentration dependence in the range studied. Experimental isotherms fitted well with the Freundlich and Sips models and the thermodynamic parameters suggested a physical adsorption mechanism in a heterogeneous surface, spontaneous at all temperatures evaluated. In brief, the activated carbon obtained from Wodyetia bifurcata can be a promising material for MB removal from aqueous solutions.

25354. 题目: Spatiotemporal distribution of nitrogen biogeochemical processes in the coastal regions of northern Beibu Gulf, south China sea
文章编号: N19091205
期刊: Chemosphere
作者: Jing Guo, Yinghui Wang, Junxiang Lai, Changgui Pan, Shaopeng Wang, Hao Fu, Bo Zhang, Yefeng Cui, Linlin Zhang
更新时间: 2019-09-12
摘要: Nitrogen biogeochemistry occupies a central role in nitrogen cycles and exerts a significant influence on primary productivity and global carbon cycles. In order to better understand the nitrogen biogeochemistry in coastal regions, spatiotemporal nitrogen fixation, denitrification and anammox were investigated in the coastal regions of northern Beibu Gulf (NBG), South China Sea (SCS). Nitrogen fixation was mainly detected in the water column of outer bays, attributed to the low nitrate concentration and low N/P (N/P < 16). Comparisons of the nitrogen fixation rates between unicellular (<10 mm) and the filamentous diazotrophs (>10 mm) indicated that the contribution of unicellular diazotrophs was more important than filamentous diazotrophs. Besides, field investigation revealed that Richelia was the dominant species in filamentous diazotrophs. On the other hand, both denitrification and anammox were found in the surface sediment and denitrification dominated the nitrogen loss process. Denitrification was mainly related to the nitrate concentration in pore water and organic matter in the sediment, while anammox was mainly regulated by the concentration of nitrate and nitrite in pore water. Additionally, temperature, dissolved oxygen (DO) and salinity also had an impact on denitrification and anammox. The net areal yield of nitrogen biogeochemical processes was estimated to be −1079t/a, as an important pathway of nitrogen removal. This study adds to the knowledge of nitrogen biogeochemistry in the nutrient-replete coastal region and highlights its significance in such an environment.

25355. 题目: The influence of land cover, including Nootka lupin, on organic carbon exports in east Icelandic rivers
文章编号: N19091204
期刊: CATENA
作者: Hannah Lehnhart-Barnett, Susan Waldron
更新时间: 2019-09-12
摘要: Fluvial dissolved and particulate organic carbon concentrations, [DOC] and [POC], were measured weekly in two contrasting catchments in east Iceland in June and July 2016. Sampling was carried out at ten sites in each catchment, including the outlets. [DOC] ranged from 2.1 to 6.6 mg L⁻¹, and [POC] from 0.4 to 3.1 mg L⁻¹. Mean TOC fluxes over the sampling period amounted to 0.46 μg m⁻² s⁻¹ from the West catchment and 0.42 μg m⁻² s⁻¹ from the East catchment. Concentration and flux data were used to analyse the relationship between organic carbon budgets and different land cover: heathland, wetland, sparse vegetation and dense Nootka lupin (Lupinus nootkatensis). Wetland area, associated with C-rich Histic Andosols, was found to have a significant positive influence on in-stream organic carbon concentrations and fluxes, and the opposite was found with sparsely vegetated areas, likely due to limited soil development. Areas with dense lupin cover were associated with relatively-low organic carbon fluxes in the East catchment, possibly because lupin stabilises its substrate, reducing mobilisation of DOC and POC. In the West catchment this influence was not clear, but this is likely due to the co-location of wetland, causing increased C exports.

25356. 题目: Increasing soil carbon stocks in eight typical forests in China
文章编号: N19091203
期刊: Biogeosciences
作者: Jianxiao Zhu, Chuankuan Wang, Zhang Zhou, Guoyi Zhou, Xueyang Hu, Lai Jiang, Yide Li, Guohua Liu, Chengjun Ji, Shuqing Zhao, Peng Li, Jiangling Zhu, Zhiyao Tang, Chengyang Zheng, Richard A. Birdsey, Yude Pan, and Jingyun Fang
更新时间: 2019-09-12
摘要: Forest soils represent a major stock of organic carbon (C) in the terrestrial biosphere, but the dynamics of soil organic carbon (SOC) stock are poorly quantified, especially based on direct field measurements. In this study, we investigated the 20-year changes in the SOC stocks at eight sites from southern to northern China. The averaged SOC stocks increased from 125.2 ± 85.2 Mg C ha⁻¹ in the 1990s to 133.6 ± 83.1 Mg C ha⁻¹ in the 2010s across the forest sites, with a mean increase of 127–908 kg C ha⁻¹ yr⁻¹. This SOC accumulation was resulted primarily from both leaf litter and fallen logs and equivalent to 3.6–16.3 % of aboveground net primary production. Our findings provide strong evidence that China's forest soils have been acting as significant carbon sinks although their strength varies with forests in different climates.

25357. 题目: Spatial and temporal changes of soil properties and soil fertility evaluation in a large grain-production area of subtropical plain, China
文章编号: N19091202
期刊: Geoderma
作者: Shuai Chen, Bowen Lin, Yanqiang Li, Sining Zhou
更新时间: 2019-09-12
摘要: Understanding the spatial and temporal characterization of soil properties, along with soil management practices, helps in analyzing soil properties changes and timely adjusting management patterns. Moreover, soil fertility evaluation within farmland is urgently needed for understanding soil fertility level and avoiding soil degradation. This study addressed the spatial and temporal changes of both soil properties and soil fertility, and their causes in a large grain-production area of China's subtropical plain, which has been used as the national commodity grain base for 35 years. In 2007 and 2017, 827 and 733 soil samples were collected across the area, respectively. Soil pH, organic matter (OM), available nitrogen (AN), available phosphorus (AP) and available potassium (AK) were measured. The changes of soil properties were analyzed with the descriptive statistics methods and geostatistical methods, while the soil integrated fertility index (IFI) was calculated by the integrated fertility index method combined with the minimum data set method. In general, 2017 had a lower variability than 2007 for all properties except AP, and pH had a lower variability than other indicators. Differences of all indexes among 6 cropping systems and 2 crop years were significant, and oilseed rape-soybean cropping system performed better than other cropping systems in most indexes. Moreover, in 2007 there was a stronger spatial dependence than in 2017, and AP and OM had a stronger spatial dependence than other indicators. Mapping indicated that a more patchy distribution of all indicators was found in 2007 than in 2017. In addition, OM and AK in soil decreased substantially, and AN decreased slightly, but AP and pH increased. By principal component analysis and correlation analysis selected OM, AP and AK as soil IFI evaluation indexes, and their weights were determined. The IFI results showed that soil fertility declined in all areas, while the double rotation systems had higher soil fertility levels than the continuous single cropping systems. These results confirm that long-term scale planting can reduce spatial variability and dependence of properties and homogenize soil properties. Our findings demonstrated that the changes of cropping systems, the differences of fertilization and the reduction of acid rain were the three important reasons for the changes of soil properties and soil fertility in Jianli county in recent years. In this study area, effective measures should be taken to increase OM, AP and AK contents in soil.

25358. 题目: Estimating the mineral surface area of soils by measured water adsorption. Adjusting for the confounding effect of water adsorption by soil organic carbon
文章编号: N19091201
期刊: European Journal of Soil Science
作者: Miko UF Kirschbaum, Donna L Giltrap, Sam R McNally, Lìyǐn L Liáng, Carolyn B Hedley, Gabriel YK Moinet, Michael Blaschek, Michael H Beare, Benny KG Theng, John E Hunt, David Whitehead
更新时间: 2019-09-12
摘要: Specific surface area can be a strong predictor of organic carbon (SOC) contents in soils. Specific surface area can be estimated reliably and cost‐effectively from water adsorption by air‐dry soil samples, but SOC itself can also adsorb water. For estimating the mineral component of specific surface area, it is, therefore, necessary to exclude water‐adsorption by SOC. Here, we refer to ‘apparent specific surface area’ for measurements that include water adsorption by both mineral soil and SOC. We used a mathematical approach to estimate water adsorption by SOC so that this component can be subtracted from measurements of apparent specific surface area.

25359. 题目: Characteristics and Stability of Incidental Iron Oxide Nanoparticles during Remediation of a Mining-Impacted Stream
文章编号: N19091112
期刊: Environmental Science & Technology
作者: Logan N Rand, James F. Ranville
更新时间: 2019-09-11
摘要: Acid mine drainage (AMD) produces nanoparticulate Fe oxides and sorbed toxic metals, such as Cu and Zn. As an indirect product of human activity, these Fe oxides can be classified as incidental nanoparticles (INPs) and their colloidal aggregates. Research in nanoparticle fate and transport has advanced with the development of single particle inductively coupled plasma-mass spectrometry (spICP-MS), but AMD INPs have received little attention. We examined the characteristics and abundance of Fe oxide INPs in an AMD-impacted stream over the first 6 months of remediation. Fe and Cu INP concentrations were approximately 107 and 105 particles mL–1, before and after treatment, respectively. Overall, ∼4 Cu-containing INPs were counted for every 100 Fe-containing INPs. We also studied surface chemistry changes during the treatment period using hematite, a model Fe INP, suspended in filtered field waters. Changes in zeta potential and INP size, measured by dynamic light scattering, support that the contaminated stream chemistry (low pH, high ionic strength) promoted rapid aggregation while improved water quality favored stability. However, the water chemistry and INP stability during snowmelt were additionally impacted by electrolyte dilution, the addition of dissolved organic matter, and physical scouring. By linking field measurements to laboratory experiments, this work explores the effects of surface chemistry on AMD-generated INP behavior before and during remediation in a hydrologically dynamic alpine stream. To our knowledge, this is the first investigation of remediation effects on AMD INPs and the first use of spICP-MS as a technique to measure them.

25360. 题目: Lignin from white-rotted European beech deadwood and soil functions
文章编号: N19091111
期刊: Biogeochemistry
作者: Kenton P. Stutz, Klaus Kaiser, Janna Wambsganss, Fernanda Santos, Asmeret Asefaw Berhe, Friederike Lang
更新时间: 2019-09-11
摘要: In forest ecosystems, deadwood can improve carbon storage, nutrient availability, and water holding capacity in soils. Yet the effect of organic matter from deadwood such as lignin on these soil functions and their regulators are unknown. We hypothesized that carbon storage, exchangeable cations, and pore space increase with the quantity of lignin-derived phenolic acids from beech deadwood. We also hypothesize that the most pronounced differences occur in more advanced decay classes, in the forest floor at sites with moder forest floors, and in the Ah horizon at sites with mull forest floors. Cupric oxide-oxidation products were used to determine lignin concentration, composition, and oxidation from paired reference and test samples next to 42 downed European beech (Fagus sylvatica L.) deadwood logs in ten stands in Southwest Germany. Compared to reference points, the sum of vanillyl, syringyl and cinnamyl lignin-derived phenols increased next to beech deadwood (within 10–20 cm). The composition and oxidation of lignin-derived phenols also changed near beech deadwood: syringyl/vanillyl ratios increased while cinnamyl/vanillyl and aldehyde/acid ratios for vanillyl decreased. Water-extractable organic carbon (OC) and its aromaticity also increased next to beech deadwood as did total OC and particulate OC separated by density fractionation relative to total and mineral-bound OC. These changes occurred namely in the organic horizons of moder forest floors, and in the Ah horizon underneath mull forest floors. These observations indicated that phenols predominantly entered soil in fluxes of fragmented and dissolved organic matter from beech deadwood. Changes to soil nutrient availability and porosity were linked to increasing lignin-derived phenols from beech deadwood especially in nutrient-poor soils and near heavily decayed deadwood. This is evidence that soils close to beech deadwood, a substrate, are spatially limited pedogenic hot-spots that have increased soil carbon, available nutrients, and pore space depending on the forest floor and parent material.