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26541. 题目: Tripolyphosphate-assisted electro-Fenton process for coking wastewater treatment at neutral pH
文章编号: N19030212
期刊: Environmental Science and Pollution Research
作者: Fengxia Deng, Shan Qiu, Yingshi Zhu, Xiaoxiao Zhang, Jixian Yang, Fang Ma
更新时间: 2019-03-02
摘要: The first application of a novel electro-Fenton (EF) for coking wastewater (CW) treatment at the original pH (6.80) by using tripolyphosphate (TPP) ligand was proposed. Total organic carbon (TOC) decay of CW followed a pseudo-first kinetic rate constant with an apparent rate constant (k_app) of 1.07 × 10⁻² min⁻¹ for the EF in the presence of TPP (EF/TPP), which was 2.10 times higher than that of conventional EF (k_app = 5.10 × 10⁻³ min⁻¹) working at pH 3. The high efficiency of EF/TPP at neutral pH was mainly attributed to the newly formed Fe-O-P coordination in the iron-ligand compound (Fe²⁺-TPP) supported by UV-absorption spectra results, activating oxygen to produce ^•OH and hence enhancing the oxidation capacity. Key operating parameters of CW mineralization by EF/TPP including Fe²⁺ concentration and pH value were systematically investigated. Excitation-emission matrix (EEM) spectra technique was used to assess the variance of dissolved organic matters during the EF/TPP process. Results showed an 81% mineralization of CW after 3 h electrolysis coupled with a low energy consumption (0.129 kWh g⁻¹ TOC) which were obtained by the EF/TPP process. Microtox toxicity demonstrated that TPP could reduce the toxicity of raw CW and importantly, it showed that EF/TPP was effective for detoxification. Mechanism study via simulated matrix with similar components as CW revealed that ^•OH produced both from Fenton and Fe²⁺-TPP activation together with the generated active chlorine was responsible for CW mineralization. In summary, the TPP-assisted EF process was presented as a promising technique for extending coking wastewater treatment at near-neutral pH with a high mineralization. -

26542. 题目: Organic Carbon and Nitrogen Stocks along a Thermokarst Lake Sequence in Arctic Alaska
文章编号: N19030211
期刊: Journal of Geophysical Research: Biogeosciences
作者: Matthias Fuchs, Josefine Lenz, Suzanne Jock, Ingmar Nitze, Benjamin M. Jones, Jens Strauss, Frank Günther, Guido Grosse
更新时间: 2019-03-02
摘要: Thermokarst lake landscapes are permafrost regions, which are prone to rapid (on seasonal to decadal timescales) changes, affecting carbon and nitrogen cycles. However, there is a high degree of uncertainty related to the balance between carbon and nitrogen cycling and storage. We collected twelve permafrost soil cores from six drained thermokarst lake basins (DTLB) along a chronosequence north of Teshekpuk Lake in northern Alaska, and analyzed them for carbon and nitrogen contents. For comparison, we included three lacustrine cores from an adjacent thermokarst lake and one soil core from a non‐thermokarst affected remnant upland. This allowed to calculate the carbon and nitrogen stocks of the three primary landscape units (DTLB, lake, and upland), to reconstruct the landscape history, and to analyze the effect of thermokarst lake formation and drainage on carbon and nitrogen stocks. We show that carbon and nitrogen contents and the carbon‐nitrogen ratio are considerably lower in sediments of extant lakes than in the DTLB or upland cores indicating degradation of carbon during thermokarst lake formation. However, we found similar amounts of total carbon and nitrogen stocks due to the higher density of lacustrine sediments caused by the lack of ground‐ice compared to DTLB sediments. In addition, the radiocarbon‐based landscape chronology for the past 7,000 years reveals five successive lake stages of partially, spatially overlapping DTLBs in the study region, reflecting the dynamic nature of ice‐rich permafrost deposits. With this study, we highlight the importance to include these dynamic landscapes in future permafrost carbon feedback models.

26543. 题目: The influence of humic acid on U(VI) sequestration by calcium titanate
文章编号: N19030210
期刊: Chemical Engineering Journal
作者: Songhua Lu, Kairuo Zhu, Han Guo, Huihui Wang, Ning Zhang, Ahmed Alsaedi, Tasawar Hayat, Ying Li, Yubing Sun
更新时间: 2019-03-02
摘要: The influence of humic acid (HA) on U(VI) sequestration by calcium titanate (CaTiO₃) was investigated by batch experiment and spectroscopic techniques. Various characterizations, including zeta potentials, average hydrodynamic diameters, specific surface area and pore volume, have been demonstrated that HA significantly changes the surface properties of CaTiO₃. In addition, the obtained results revealed that HA enhanced U(VI) adsorption at pH < 5.0 attributed to the strong electrostatic attraction, the dispersion of particles exposed more adsorption sites and abundant oxygen-groups of surface loaded HA, whereas U(VI) sequestration was inhibited assigned to the stronger electrostatic repulsion between anionic U(VI) species and more negative surface of CaTiO₃ at pH > 6.0. XPS analysis showed that the higher sequestration of U(VI) in the existence of HA, which was ascribed to the enhanced dispersity, decreased zeta potential and more abundant surface functional groups of CaTiO3 at low pH. In addition, HA inhibited the reduction of U(VI) to U(IV) at low pH under ambient conditions. These information are significant for the understanding the surface properties of perovskite-type titanate materials and its sequestration performance of uranium in HA-rich environments.
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26544. 题目: Testing the “component additivity” approach for modelling Cu and Zn adsorption to a natural sediment
文章编号: N19030209
期刊: Chemical Geology
作者: Leanne M. Fisher-Power, Zhenqing Shi, Tao Cheng
更新时间: 2019-03-02
摘要: Surface complexation modelling (SCM) is a powerful tool for predicting metal adsorption to minerals and natural organic matter. However, the ability of SCM to predict metal adsorption to natural sediments, characterized by a great variety of co-existing inorganic and organic components, has not been fully investigated. The objective of this research was to study the effects of soil organic matter (SOM) and Fe/Al-oxyhydroxides depletion and grain-size fractionation on Cu and Zn adsorption to a natural sediment and examine the applicability of “component additivity” approach for modelling metal adsorption to natural sediments. A natural sediment sample was separated into six portions, one of which was unmodified, and the others chemically treated to remove SOM, Fe/Al-oxyhydroxides, or both SOM and Fe/Al-oxyhydroxides, or separated into coarse and fine grain-size fractions. Each of the six variations of the sediment was characterized and used in adsorption experiments. Experimental results showed that Cu and Zn adsorption decreased substantially when SOM and Fe/Al-oxyhydroxides in the sediment were removed, and that the coarse grain-size fraction adsorbed lower amounts of Cu and Zn, whereas the fine fraction adsorbed similar amount of Cu but higher amount of Zn compared to the unmodified sediment. A surface complexation model, in which only SOM, Fe/Al-oxyhydroxides, and clays were considered as active adsorbents, with their metal adsorption quantified using models independently developed by previous studies, successfully simulated Cu and Zn adsorption to the sediments using the “component additivity” approach. The percentage of active organic carbon (f_o) and percentage of active Fe/Al-oxyhydroxides (f_Fe/Al-oxides) were found to play critical roles in determining the accuracy of the model and had to be adjusted based on sediment type to reflect the distinct metal binding properties of SOM and Fe/Al-oxyhydroxides in different types of sediments.

26545. 题目: Storage, pattern and driving factors of soil organic carbon in an ecologically fragile zone of northern China
文章编号: N19030208
期刊: Geoderma
作者: Xuyang Wang, Yuqiang Li, Xiangwen Gong, Yayi Niu, Yinping Chen, Xiaoping Shi, Wei Li
更新时间: 2019-03-02
摘要: Knowledge of the spatial pattern of soil organic carbon (SOC) and its influencing factors is important for understanding the carbon cycle. We investigated the SOC density (SOCD) to a depth of 30 cm from ground surface at 644 sites in an agro-pastoral ecotone of northern China that covered 654,564 km². SOC storage to a depth of 30 cm was 2360 Tg, and SOCD averaged 3.78 kg·m⁻² for the entire study area. SOCD to a depth of 20 cm and from 20 to 30 cm showed strong and moderate spatial dependence, with a nugget to sill ratio of 0.7% and 43.5%, respectively. Overall, SOCD increased from southwest to northeast, it was more strongly correlated with latitude than with longitude. Forest and sandy land had the highest and lowest SOCD, at 6.28 and 1.76 kg·m⁻², respectively. The SOCD (kg·m⁻²) of grassland decreased with decreasing vegetation cover: high (4.42) > medium (3.62) > low (2.50). For the common soils in the study area, the highest mean SOCD was 9.31 kg·m⁻² in Grey Forest Soils, versus 1.75 kg·m⁻² in Brown Pedocals. In the study area, temperature appears to be the dominant factor that influences SOC, and SOCD decreased with increasing temperature. However, topographic factors (elevation, slope, and aspect) had a weaker effect on SOC. Our results provide a valuable baseline for future research on the long-term evolution of SOCD.

26546. 题目: Fractionation and risk assessment of metals in sediments of an ocean dumping site
文章编号: N19030207
期刊: Marine Pollution Bulletin
作者: Jun-Mo Jung, Ki-Young Choi, Chang-Soo Chung, Chang-Joon Kim, Suk Hyun Kim
更新时间: 2019-03-02
摘要: Sediments of Yellow Sea dumping sites (YSDS) collected in 2015 were analyzed using the European Community Bureau of Reference (BCR) sequential extraction method to assess the contamination and potential risk to the environment. Cr, Ni, Cu, and Zn exhibited the most dominant residual fraction, whereas Cd was mostly in the exchangeable fraction and Pb in the reducible fraction. Cr contains a significant amount of oxidizable fraction in the dumping area due to the dumping of tannery sludge with high concentrations of Cr, mainly in the organic matter-bound form. The global contamination factor (GCF) showed that high non-residual fractions of Cd and Pb contributed considerably to contamination. Nevertheless, modified potential ecological risk index (MRI) suggested low ecological risk for metals in YSDS because of the low total content of Cd and the small mobile fraction of other metals.

26547. 题目: Combining the microbial calcite precipitation process with biochar in order to improve nickel remediation
文章编号: N19030206
期刊: Applied Geochemistry
作者: Jing Zhang, Deepika Kumari, Chaolin Fang, Varenyam Achal
更新时间: 2019-03-02
摘要: Microbially induced calcite precipitation (MICP) is a promising technology in the remediation of heavy metals, while biochar is a valuable adsorbent for its removal. In the present study, biochar was added to the MICP process to investigate its effect on the remediation of nickel (Ni). The MICP process immobilized 89% and 66% of Ni²⁺ at initial concentrations of 50 and 100 mg L⁻¹, respectively. However, biochar had an inhibitory effect on the calcite produced by Bacillus cereus NS4 and suppressed the Ni remediation. The mechanism of suppression by biochar was elucidated by scanning electron microscopy-energy dispersion spectrophotometry, Fourier transform infrared spectroscopy, and X-ray diffraction techniques. Biochar caused weakening of the adsorption bonds responsible for carbonate formation led to dissociation of the carbonate structure. This is the first study to combine biochar with the MICP process and provides reference data for better understanding of the mechanism of suppression of carbonate precipitation by biochar.

26548. 题目: Sorption and leaching behavior of bithionol and levamisole in soils
文章编号: N19030205
期刊: Chemosphere
作者: Xuan Ma, Xueping Liu, Sanglan Ding, Shijun Su, Zhiwei Gan
更新时间: 2019-03-02
摘要: The batch experiments were conducted to understand sorption process of bithionol (BIT) in yellow soil (YS) and red soil (RS), while column leaching experiments were performed to evaluate the leaching behavior of BIT and levamisole (LEV) in the tested soils. The adsorption and desorption data fitted well with the Freundlich isotherms (R² ≥ 0.94). The distribution coefficient of BIT in the YS and RS were 104 and 98.3 L/kg, respectively. Hysteresis was observed for bithionol desorption in the YS and RS, with hysteresis coefficient of 0.917 and 0.928, respectively. Dissolved organic matter (DOM) addition and acid condition enhanced the adsorption of BIT in the soil. Both BIT and LEV showed poor leaching potential in the tested soils. More than 80% of BIT and LEV remained in the surface soil layer and the amount of the two target compounds in the leachates accounted for less than 1% of overall recovery. DOM showed little influence on the concentration of BIT and LEV in the leachates collected at different time. The results could fill the gap on the behavior of BIT and LEV in soil under laboratory conditions.

26549. 题目: Growth promotion of greenhouse tomatoes with Pseudomonas sp. and Bacillus sp. biofilms and planktonic cells
文章编号: N19030204
期刊: Applied Soil Ecology
作者: Emily Ricci, Timothy Schwinghamer, Di Fan, Donald L. Smith, Valérie Gravel
更新时间: 2019-03-02
摘要: The effects on plants of commercial applications of biofertilizer and biocontrol agents containing planktonic rhizobacteria cells are inconsistent mainly due to an unsuccessful competition with existing endogenous microbial communities. The present study investigated rhizobacteria inoculants in the form of biofilms, which are dense colonies of single or multi-species microbial cells, adherent to either biotic or abiotic surfaces, and encased in a self-produced matrix composed of extracellular polymeric substances. Bacillus sp., Pseudomonas sp., or a mixed inoculum of both bacteria at the planktonic or biofilm stage of growth were applied to greenhouse-grown tomato (Solanum lycopersicum L. cv Trust) plants fertilized with a half strength Hoagland solution or a modified solution lacking phosphate or iron. Based on multivariate analysis of variance, availability of nutrients, bacteria, and stages of bacterial growth significantly affected plant variables known to be contributing factors to greenhouse tomato yield. Results suggest that Bacillus sp. and Pseudomonas sp. biofilms are more effective inoculants than planktonic bacteria cells. Pseudomonas sp. applied as a biofilm increased the height and root dry weight of tomato plants, but it inhibited the positive effects of inoculation on tomato leaf number and tomato root length. Path analysis identified positive causal paths from (Pseudomonas) biofilm and planktonic cells, to the tomato plant growth variables. Presence of Bacillus sp. alone or in a mixture inhibited the positive effects of inoculation on tomato plant leaf area and root dry weight. Nevertheless, the effect of Bacillus sp. on root length was relatively positive. Results suggest that the use of innovative rhizobacteria biofilm technologies could prove advantageous as biofertilizer agents, and alleviate the dependence of greenhouse tomato producers on non-biological agro-chemicals.

26550. 题目: Decomposition of an N-fixing invasive plant compared with a native species: Consequences for ecosystem
文章编号: N19030203
期刊: Applied Soil Ecology
作者: Elizabete Marchante, Hélia Marchante, Helena Freitas, Annelise Kjøller, Sten Struwe
更新时间: 2019-03-02
摘要: Invasion by the Australian Acacia longifolia has significantly altered the characteristics of both vegetation and soil of Portuguese coastal dunes, including the accumulation of a thick litter layer. Although many aspects of impacts by this species in invaded dunes are known, decomposition of the litter is not well studied, but this can be crucial to disentangle both impacts and recovery. In order to better understand the impacts at soil level and the recovery of the system after removal of the invader, decomposition of A. longifolia litter was studied and compared with decomposition of the native Cistus salviifolius, for >3 years. Litterbags were deployed in a coastal sand dune and samples retrieved after 2, 5, 11, 17, 24, 36 and 41 months. At the final sampling, ca. 41% and 48% of the initial litter mass of A. longifolia and C. salviifolius, respectively, remained, showing that in these dunes both species decompose slowly. During the first 17 months, A. longifolia decomposed faster than C. salviifolius, but thereafter the rate slowed down and C. salviifolius was decomposed at a faster rate. In general, throughout decomposition, N and lignin content, lignin/cellulose ratio, cellulase and chitinase activity, and the number of microfungi morphotypes were significantly higher in A. longifolia than in C. salviifolius litter. On the other hand, C/N ratio, cellulose content and the number of microfungal isolates were generally higher in C. salviifolius litter. Mostly for A. longifolia, lignin content and lignin/N ratio increased as the remaining litter mass decreased. Despite high N content and low lignin/N and C/N ratios, almost 43% of the A. longifolia litter is recalcitrant/very slowly decomposed, accumulating on soil surface for long periods. The slow decomposition rate of A. longifolia litter together with the production of much more litter than the native vegetation (ca. 3 times more than C. salviifolius) is reflected in the accumulation of a thick N-rich litter layer on soil surface of invaded areas. This promotes a continuous input of C and nutrients to the soil, and leaves a hidden legacy long after the removal of the invader that, amongst other impacts, prevents the regeneration of native species.

26551. 题目: Impacts of green manure amendment on detritus micro-food web in a double-rice cropping system
文章编号: N19030202
期刊: Applied Soil Ecology
作者: Yunfeng Chen, Ning Hu, Qingzhong Zhang, Yilai Lou, Zhongfang Li, Zheng Tang, Yakov Kuzyakov, Yidong Wang
更新时间: 2019-03-02
摘要: Chinese milk vetch (CMV) is widely used as a green manure due to its efficiency for nutrient preservation and soil fertility improvement, as well for providing more organic substances for soil organisms. Detritus micro-food web drives carbon and nutrient cycling and maintains ecosystem productivity. The effects of CMV amendment on detritus micro-food web were investigated in a six-year field experiment. Compared to the mineral fertilizers (NPK) alone, the fertilizers combined with CMV (NPK + CMV) increased soil organic carbon content, and thus enhanced the biomass of microorganisms, as well as protozoa abundance, while did not change micro-feeding nematode abundance (MN). This indicates a substrate-driven bottom-up effect. However, the green manure application increased omnivores-predators (OP) abundance and the OP/MN ratio, suggesting a top-down effect. Higher F/B ratio indicates a shift of the food web energy structure towards to fungi-dominated channel in the manured soil. Here, the green manure amendment should be encouraged to improve soil detritus micro-food web.

26552. 题目: Effects of land-use change on chemical attributes of a Ferralsol in Brazilian Cerrado
文章编号: N19030201
期刊: CATENA
作者: Fabiane Pereira Machado Dias, Rodrigo Hübner, Flávia de Jesus Nunes, Wilson Mozena Leandro, Francisco Alisson da Silva Xavier
更新时间: 2019-03-02
摘要: The expansion of agriculture in the Brazilian Cerrado biome occurs at the expense of replacing native forest with pasture and/or crops. Negative environmental impacts, such as soil degradation, have been observed during this process. We aimed to evaluate the effect of different agricultural management systems on chemical attributes and soil organic matter fractions of a Ferralsol in an area of Cerrado, in the municipality of Hidrolândia, Goiás, Brazil. The following management systems were evaluated: (a) pasture (PAST), (b) no-tillage system (NT), organic cultivation (ORG) systems with different years of cultivation (2, 6, 8, and 10 years), and (c) a conventional management system (CS). Further, an area under native Cerrado forest (NF) was selected and used as a reference for steady state. Soil cores were collected at 0.0–0.10, 0.10–0.20, and 0.20–0.40 m depths. Macronutrients, total organic C (TOC), particulate organic C (POC), humic substances, and labile-C (Lab-C) were analyzed. The land-use change effect, driven by deforestation with subsequent pasture and/or crop, was evident by principal component (PC) analysis. In the 0.0–0.10 m soil layer, PC2 showed the isolation of NF from agricultural systems, whereas PC1 exhibited similar phenomena for the 0.10–0.20 and 0.20–0.40 m layers. In all cases, the agricultural systems showed weak correlation to TOC, POC, Lab-C and base saturation, suggesting loss of soil chemical fertility compared to NF. The ORG-8 area differed from other managed systems mainly due to high pH, P content, and base saturation. Soil cation exchange capacity was highly correlated to variables associated with soil organic matter, such as TOC, POC, and Lab-C. This result demonstrates that Cerrado soils are highly dependent on soil organic C dynamics. Conversion of Cerrado into agricultural land decreases soil chemical fertility. However, agroecosystems that reduce soil tillage and increase organic inputs, such as organic cultivation and no-tillage, seem to be suitable options for agricultural activity in Brazilian Cerrado.

26553. 题目: The influence of dissolved organic matter on the marine production of carbonyl sulfide (OCS) and carbon disulfide (CS2) in the Eastern Tropical South Pacific
文章编号: N19030110
期刊: Ocean Science Discussions
作者: Sinikka T. Lennartz, Marc von Hobe, Dennis Booge, Henry Bittig, Tim Fischer, Rafael Gonçalves-Araujo, Kerstin B. Ksionzek, Boris P. Koch, Astrid Bracher, Rüdiger Röttgers, Birgit Quack, Christa A. Marandino
更新时间: 2019-03-01
摘要: Oceanic emissions of the climate relevant trace gases carbonyl sulfide (OCS) and carbon disulfide (CS2) are a major source to their atmospheric budget. Their current and future emission estimates are still uncertain due to incomplete process understanding and, therefore, inexact quantification across different biogeochemical regimes. Here we present the first concurrent measurements of both gases together with related fractions of the dissolved organic matter (DOM) pool, i.e. solid-phase extractable dissolved organic sulfur (DOSSPE), chromophoric (CDOM) and fluorescent dissolved organic matter (FDOM) from the Eastern Tropical South Pacific (ETSP). These observations are used to estimate in-situ production rates and identify their drivers. We find different limiting factors of marine photoproduction: while OCS production is limited by the humic-like DOM fraction that can act as a photosensitizer, high CS2 production coincides with high DOSSPE concentration. The lack of correlation between OCS production and DOSSPE may be explained by the active cycling of sulfur between OCS and dissolved inorganic sulfide via OCS photoproduction and hydrolysis. In addition, the only existing parameterization for OCS dark production is validated and updated with new rates from the ETSP and the Indian Ocean. Our results will help to predict oceanic concentrations and emissions of both gases on regional and, potentially, global scales.

26554. 题目: Spatially variable bioturbation and physical mixing drive the sedimentary biogeochemical seascape in the Louisiana continental shelf hypoxic zone
文章编号: N19030109
期刊: Biogeochemistry
作者: Richard Devereux, John C. Lehrter, Giancarlo Cicchetti, David L. Beddick, Diane F. Yates, Brandon M. Jarvis, Jessica Aukamp, Marilynn D. Hoglund
更新时间: 2019-03-01
摘要: Seasonal hypoxia on the Louisiana continental shelf (LCS) has grown to over 22,000 km² with limited information available on how low oxygen effects the benthos. Benthic macrofaunal colonization and sediment biogeochemical parameters were characterized at twelve stations in waters 10–50 m deep along four transects spanning 320 km across the LCS hypoxic zone in the early fall of 2010 when bottom waters typically return to oxic conditions. Chemical data and sediment profile imaging (SPI) support three primary mechanistic pathways of organic matter degradation on the LCS: (i) metal oxide cycling in depositional muds, (ii) infauna-driven bioturbation delivering oxygen below the sediment–water interface, and (iii) sulfate reduction in sediments where iron oxide availability is limited. The transect nearest the Mississippi River delta had the highest concentrations of porewater and solid phase Mn and Fe with SPI images of recently deposited reddish, mixed muddy sediments suggestive of metal cycling. The deepest stations had high oxidized iron concentrations and rust colored sediments with faunal colonization that suggests sediments are oxidized via bioturbation. Many nearshore and central LCS stations had more black sediments, more disturbed clay layers, lower amounts of oxidized iron, and higher sulfate reduction rates than the deepest stations. Sediment mixing coefficients, D_B, determined from chlorophyll-a concentration profiles varied between 33 and 183 cm⁻² year⁻¹. D_B values were highest at the deepest stations where sediments were colonized. D_B were not determined at two nearshore stations where chlorophyll-a concentrations were highly variable in surficial sediments, and on the eastern shelf where sedimentation is high. This study provides a regional view of benthic faunal colonization and sediment biogeochemistry on the LCS, describes regions with potentially different pathways of organic matter degradation, and demonstrates the importance of both bioturbation and physical mixing in processing the large amounts of organic matter in river-dominated continental shelf systems.

26555. 题目: Sonocatalytic degradation of butylparaben in aqueous phase over Pd/C nanoparticles
文章编号: N19030108
期刊: Environmental Science and Pollution Research
作者: Georgios Bampos, Zacharias Frontistis
更新时间: 2019-03-01
摘要: In the present work, the sonocatalytic degradation of butylparaben was investigated using Pd immobilized on carbon black as the sonocatalyst. The presence of 25 mg/L 10Pd/C significantly increased the removal rate of butylparaben and the observed kinetic constant increased from 0.0126 to 0.071 min⁻¹, while the synergy index between sonolysis and adsorption was 70.7%. The BP degradation followed pseudo-first-order kinetics with the apparent kinetic constant decreased from 0.071 to 0.030 min⁻¹ when the initial concentration of butylparaben increased from 0.5 to 2 mg/L. The process was being favored slightly under alkaline conditions. The presence of organic matter (20 mg/L humic acid) reduced the apparent kinetic constant more than two times. The addition of chlorides up to 250 mg/L did not significantly reduce the rate of reaction, while the presence of 250 mg/L bicarbonates reduced the observed kinetic constant from 0.071 to 0.0472 min⁻¹. The prepared catalyst retains the efficiency after five subsequent experiments since the apparent kinetic constant was only slightly decreased from 0.071 to 0.059 min⁻¹.

26556. 题目: Feasibility of agricultural residues and their biochars for plant growing media: Physical and hydraulic properties
文章编号: N19030107
期刊: Waste Management
作者: Golnoosh Banitalebi, Mohammad Reza Mosaddeghi, Hossein Shariatmadari
更新时间: 2019-03-01
摘要: This study was conducted to examine feasibility of using some agricultural residues and their biochars as substitutes for commercial horticultural growing media as cocopeat, sand, perlite, zeolite, pumice, vermiculite and rockwool. Biochars of wheat straw, sawdust, rice hull, sugarcane bagasse and date palm bunches were produced at 300 and 500 °C. Following substrate properties were determined: easily available water (EAW) defined by the difference between water contents (θ) at absolute matric potentials (h) of 10 and 50 hPa (EAW = θ₁₀ − θ₅₀), air after irrigation (AIR = θ₀ − θ₁₀), water holding capacity (WHC = θ₁₀), water buffering capacity (WBC = θ₅₀ − θ₁₀₀), saturated water content (θ_s), bulk density (BD), total porosity (TP), water drop penetration time (WDPT), pH and electrical conductivity (EC). A classification system was developed to evaluate the substrates as horticultural growing media. Higher pyrolysis temperature produced biochars with higher pH, EC, TP, θ_s, WHC, EAW, and WBC and lower biochar yield, AIR, BD and WDPT. Sugarcane bagasse biochars had higher θ_s, TP and WBC and lower BD than other biochars. Comparison among organic residues and inorganic substrates showed that highest TP, θ_s and EAW were observed in rockwool, whereas, among organic residues, maximum values of these properties were achieved for sugarcane bagasse, wheat straw and sawdust, respectively. Considering pH, EC, BD, TP, EAW, AIR, WBC and WDPT, wheat straw and sawdust were classified as very good substrates similar to cocopeat and rockwool. Other organic residues were placed in good class. Wheat straw and date palm bunches biochars produced at 500 °C and sugarcane bagasse and rice hull biochars were good growing media and can be suitable candidates for amendments or replacements of commercial growing media.

26557. 题目: Evaluation of algal photosynthesis inhibition activity for dissolved organic matter with the consideration of inorganic and coloring constituents
文章编号: N19030106
期刊: Chemosphere
作者: Kentaro Misaki, Yuhei Morita, Kentaro Kobayashi, Yuichi Sugawara, Yoshihisa Shimizu, Taketoshi Kusakabe
更新时间: 2019-03-01
摘要: The effect of waterborne ingredient on ecosystem has been of great interest. In the present study, the evaluation method using algal photosynthesis inhibition assay with dual-channel pulse amplitude modulation (PAM) system was established for a series of water samples to elucidate the potential effect of the total body of organic compounds including natural organic matter (NOM) on aquatic ecosystems. The more sensitive and less time-consuming monitoring method compared with algal growth inhibition assay was suggested, especially considering inorganic and coloring constituents. Algal photosynthesis inhibition activity was detected with high sensitivity for photosystem II (PSII) inhibitors, whereas the IC₁₀ of the other chemicals was over the environmental standard concentration for Chlamydomonas moewusii (Chlorophyceae) and Pheodactylum tricornutum (Diatomea). The photosynthesis inhibition activity of Lake Biwa dissolved organic matter (LBDOM) and fulvic acid (LBFA) was significantly detected at ≥10 times the concentration and >10 mgC L⁻¹, respectively, whereas prominent activity was confirmed for Suwannee River NOM (SRNOM) on the river original concentration (>30 mgC L⁻¹) for both algae. Significant inhibition activity was detected in both algae at least in twice-concentration for water samples from a wastewater treatment pilot plant. There was no great difference in the activity between sewage secondary effluent and its filtrate with ultrafiltration (UF), and physically washing water for the UF membrane.

26558. 题目: Floodplain dynamics in North American permafrost regions under a warming climate and implications for organic carbon stocks: A review and synthesis
文章编号: N19030105
期刊: Earth-Science Reviews
作者: Katherine B. Lininger, Ellen Wohl
更新时间: 2019-03-01
摘要: Although there have been studies on changes to hydrology in permafrost regions and exports of nutrients and organic matter to the Arctic Ocean, little is known about how geomorphic dynamics of rivers in permafrost regions will change in the future under a warming climate and the effects of those changes on floodplains. We focus on river dynamics in the context of channel-floodplain interactions and the implications for organic carbon storage in floodplains. As sites of nutrient processing and storage of sediments and organic matter, changes in channel and floodplain form and process will impact sediment yields, nutrient and organic matter export to the Arctic Ocean, aquatic and riparian habitat, and infrastructure. We present a review of the factors influencing reach-scale river dynamics, using the framework of factors affecting erosive force and erosional resistance of banks and floodplain surfaces, which will change due to a warming climate. We summarize studies indicating how observed and modeled trends in these factors will affect erosive force and erosional resistance in the future. We then hypothesize the net effects that these changes will have on the ratio of erosive force to erosional resistance, and the cascading effects on channel and floodplain form and process. We describe two scenarios that could occur under different conditions in the form of conceptual models, one in which the ratio of erosive force and erosional resistance decreases, and one in which the ratio increases. An increase in the ratio of erosive force to erosional resistance due to a reduction in permafrost extent and depth and an overall increase in discharge would increase bank erosion, bank failures, sediment supply, and lateral channel migration rates, decreasing floodplain turnover time and the age of riparian vegetation. A decrease in the ratio of erosive force to erosional resistance due to a reduction in erosive force relative to sediment supply would cause enhanced deposition within the river corridor. Regardless of which scenario may occur, changes in channel process and form will influence the ratio of lateral to vertical accretion, change the nature and stored amount of floodplain sediment, and change the sources and storage of organic carbon within floodplains.

26559. 题目: The adverse effect of biochar to aquatic algae- the role of free radicals
文章编号: N19030104
期刊: Environmental Pollution
作者: Ying Zhang, Ruixin Yang, Xiaohui Si, Xingwei Duan, Xie Quan
更新时间: 2019-03-01
摘要: The application of biochar in remediation and recovery of heavy metals and/or organic contaminants in water and soil is increasing. However, the adverse effect of biochar to aquatic organisms has not received enough attention. In this study, we conducted a study on the biotoxicity of biochar pyrolyzed from pine needle under oxygen-limited conditions. The toxicity of biochar was expressed with the following endpoints: cell growth, chlorophyll-a (Chl-a), reactive oxygen species (ROS), superoxide dismutase (SOD) content of Scenedesmus obliquus (S. obliquus) and the luminescence of Photobacterium phosphoreum (P. phosphoreum). Here, the effect of free radicals (FRs) contained in biochar was stressed. Our results show that the toxicity of biochar is significantly correlated with the concentration of FRs in biochar particles. Meanwhile, we found the FRs-containing biochar could induce the production of acellular ROS (such as ·OH) in water, which would also induce the production of interior cellular ROS in aquatic organisms. Our findings provide a new insight into the mechanism of toxicity aroused by biochar applications and aid in understanding its potential ecological risk.
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26560. 题目: Dissolved Organic Matter at the Fluvial-Marine Transition in the Laptev Sea Using in situ Data and Ocean Color Remote Sensing
文章编号: N19030103
期刊: Biogeosciences
作者: Bennet Juhls, Pier Paul Overduin, Jens Hölemann, Martin Hieronymi, Atsushi Matsuoka, Birgit Heim, and Jürgen Fischer
更新时间: 2019-03-01
摘要: River water is the main source of dissolved organic carbon (DOC) in the Arctic Ocean. DOC plays an important role in the Arctic carbon cycle and its export from land to sea is expected to increase as ongoing climate change accelerates permafrost thaw. However, transport pathways and transformation of DOC in the land-to-ocean transition are mostly unknown. We collected DOC and a_CDOM(λ) samples from 11 expeditions to river, coastal and offshore waters and present a new DOC-a_CDOM(λ) model for the fluvial-marine transition zone in the Laptev Sea The a_CDOM(λ) characteristics revealed that the DOM in samples of this dataset are primarily of terrigenous origin. Observed changes in a_CDOM and its spectral slopes indicate that DOM is modified by microbial- and photo-degradation. Ocean Color Remote Sensing (OCRS) provides the absorption coefficient of colored dissolved organic matter (a_CDOM(λ)^sat) at λ = 440 or 443 nm, which can be used to estimate DOC concentration at high temporal and spatial resolution over large regions. We tested the statistical performance of five OCRS algorithms and evaluated the plausibility of the spatial distribution of derived a_CDOM(λ)^sat. The ONNS algorithm showed the best performance compared to in situ a_CDOM(440) (r² = 0.72). Additionally, we found ONNS-derived a_CDOM(440), in contrast to other algorithms, to be partly independent of sediment concentration, making ONNS the most suitable a_CDOM(λ)^sat algorithm for the Laptev Sea region. The DOC-a_CDOM(λ) model was applied to ONNS-derived a_CDOM(440) and retrieved DOC concentration maps showed moderate agreement to in situ data (r² = 0.53). The in situ and satellite-retrieved data were offset by up to several days, which may partly explain the weak correlation for this dynamic region. Satellite-derived surface water DOC concentration maps from MERIS satellite data demonstrate rapid removal of DOC within short time periods in coastal waters of the Laptev Sea, which is likely caused by physical mixing and different types of degradation processes. Using samples from all occurring water types leads to a more robust DOC-a_CDOM(λ) model for the retrievals of DOC in Arctic shelf and river waters.