论文检索

总访问量：5926617次

总访客量：428874人

所有论文

25681. 题目: No‐tillage and ryegrass grazing effects on stocks, stratification and lability of carbon and nitrogen in a subtropical Umbric Ferralsol
文章编号: N19122404
期刊: European Journal of Soil Science
作者: B. Ramalho, J. Dieckow, G. Barth, P. L. Simon, A. S. Mangrich, R. C. Brevilieri
更新时间: 2019-12-24
摘要: No‐tillage farming combined with temporary cattle grazing is becoming a common practice in parts of South America. We quantified the effects of no‐tillage and winter‐grazing of annual ryegrass (Lolium multiflorum Lam.) on soil carbon and nitrogen stock, stratification ratio (concentration in 0‐5 cm to 10‐20 cm layer) and lability (based on particulate organic matter‐POM), relative to conventional tillage or ungrazed ryegrass. A nine‐year old experiment was conducted in a southern Brazilian Ferralsol. Soil under no‐tillage accumulated 1.11 Mg C ha^‐1 year^‐1 and 0.10 Mg N ha^‐1 year^‐1 to 100 cm depth relative to conventional tillage when ryegrass was not grazed, and also increased the stratification ratio of carbon (1.48 vs 1.11) and nitrogen (1.66 vs 1.17). The carbon and nitrogen lability was also greater in no‐tillage soil, as carbon and nitrogen stocks increased proportionally more in sand‐POM than in silt or clay size‐fractions (carbon lability index=1.57 vs 1.00; nitrogen lability index=1.57 vs 1.00). Semiquinone concentrations in physical fractions was 4‐28% smaller in no‐tillage, suggesting less organic matter aromaticity in this treatment. Grazing, however, caused no further improvement of stocks of carbon and nitrogen in the 0‐100 cm layer of no‐tillage soil (e.g., 209 vs 212 Mg C ha^‐1, ns), neither on stratification, nor on lability of those elements relative to ungrazed ryegrass. Overall, no‐tillage effectively promoted soil carbon and nitrogen accumulation and lability in this subtropical Ferralsol, while grazing did not compromise the gains of no‐tillage.

25682. 题目: Understanding diatoms’ past and future biogeochemical role in high latitude seas
文章编号: N19122403
期刊: Geophysical Research Letters
作者: Jeffrey W. Krause, Michael W. Lomas
更新时间: 2019-12-24
摘要: Because cold‐water diatoms’ baseline elemental density (BED) is substantially higher than temperate diatoms, previous polar studies may have underestimated diatoms’ contribution to elemental standing stocks, contribution to particulate organic carbon (POC) export and incorrectly modelled their susceptibility to future warming. We apply cold‐water diatom allometry to Arctic field samples and derived diatom growth rates ranging from 0.01–0.68 d^‐1, versus unrealistically high rates estimated using temperate diatom allometry. Reanalysis of published Southern Ocean data (AESOPS, EIFEX) shows that diatom POC was significantly underestimated. During AESOPS, diatoms could have accounted for a majority of POC export. However, during some field programs (Kerguelen Plateau), temperate allometry properly accounted for diatom biomass. We also predict that warming sea surface temperature may alter high‐latitude diatom BED, suggesting that even if abundances do not change with warming, the reduced diatom BED will likely lower the trophic‐transfer efficiency and their total carbon flow to consumers.

25683. 题目: Amino-functionalized mesoporous silica-magnetic graphene oxide nanocomposites as water-dispersible adsorbents for the removal of the oxytetracycline antibiotic from aqueous solutions: adsorption performance, effects of coexisting ions, and natural organic matter
文章编号: N19122402
期刊: Environmental Science and Pollution Research
作者: Panida Prarat, Parnuch Hongsawat, Patiparn Punyapalakul
更新时间: 2019-12-24
摘要: The amino-functionalized mesoporous silica-magnetic graphene oxide nanocomposite (A-mGO-Si) was synthesized and used for oxytetracycline (OTC) removal from water. Various factors like the effects of initial concentration, contact time, and influence of pH were investigated. Selective adsorption experiments in connection with coexisting ions and dissolved organic matter (DOM) were also investigated. In this study, humic acid (HA) and tannic acid (TA) were representative of both hydrophobic and hydrophilic DOM, respectively. Results indicated that A-mGO-Si had an adsorption ability for OTC that was relatively greater than that of virgin magnetic graphene oxide (mGO), graphene oxide (GO), Fe₃O₄ particles, and SBA-15 mesoporous silica and also showed a better uptake removal capacity for OTC at low initial concentration in comparison with the other adsorbents. The adsorption behavior of OTC onto A-mGO-Si could be described by the pseudo-second-order kinetic model and the Freundlich isotherm model. The electrostatic interaction has no influence on the OTC absorbed when the OTC is in an aqueous medium in its zwitterion form (3.22 < pH < 7.46). At high pH, the weak π–π EDA interactions and hydrogen bonding may manifest themselves, hence causing a lower adsorption capacity. The main adsorption mechanisms were plausibly activated by H-bonding, and π–π EDA interactions, while the electrostatic interaction (cation–π interaction) might be the minor adsorption mechanism. Addition of individually exogenous ions (Na⁺, Mg²⁺, NO⁻, and CO₃²⁻) resulted in a decrease of OTC adsorption due to the emergence of a competitive effect. Considering the presence of HA and TA in mixed solute systems, the DOM was likely to form a stronger interaction system with mGO-Si, thereby resulting in an adsorption level which was more competitive in the process at low aqueous phase concentration of OTC. In contrast to the high aqueous phase, the coexistence of DOM could promote OTC adsorption. The phenomenon may reflect the result that a surface complexation mechanism could achieve in adsorptions.

25684. 题目: Effects of electrolytic oxidation for mitigating ultrafiltration membrane fouling caused by different natural organic matter fractions
文章编号: N19122401
期刊: Environmental Science: Water Research & Technology
作者: Tao Xu, Li Cui, Honghan Li, Peng Zou, Jiyan Liang
更新时间: 2019-12-24
摘要: Membrane fouling is a challenging issue in terms of ultrafiltration application. However, as a novel water treatment technology, the impact of electrocatalytic oxidation on membrane fouling is still debated. Thus, in this study, to overcome this problem, the application of electrocatalytic oxidation pretreatment was evaluated for mitigating membrane fouling by natural organic matter. The influence of natural organic matter (NOM) fractions on the control efficiency was also investigated using humic acid (HA), bovine serum albumin (BSA), and sodium alginate (SA). The performance was examined through normalized flux decline, fouling resistance analysis, EEM fluorescence spectroscopy and the classical membrane fouling model. The results indicate that the electrocatalytic oxidation pretreatment exhibited a remarkable synergistic effect in the reduction of NOM, with a reduction in the DOC of 53% and 55% for HA and SA, respectively. However, the electrocatalytic oxidation pretreatment exhibited limited influence on BSA. The electrocatalytic oxidation pretreatment efficiently reduced both the reversible and irreversible fouling resistances and increased the membrane flux. The fouling mitigation by electrocatalytic oxidation was attributed to the oxidation of organic matter by ˙OH. The experimental results are expected to provide a feasible strategy for electrocatalytic oxidation to mitigate fouling.
图文摘要:

25685. 题目: Iron-loaded carbon nanotube-microfibrous composite for catalytic wet peroxide oxidation of m-cresol in a fixed bed reactor
文章编号: N19122302
期刊: Environmental Science and Pollution Research
作者: Yi Yang, Huiping Zhang, Haoxin Huang, Ying Yan, Xinya Zhang
更新时间: 2019-12-23
摘要: A kind of novel iron-loaded carbon nanotube-microfibrous composite (Fe₂O₃-CNT-MF) catalyst is prepared and tested for fixed bed m-cresol catalytic wet peroxide oxidation (CWPO) reaction. Results show that the Fe₂O₃-CNT-MF can significantly decline the pressure drop of the fixed bed. Higher temperature, lower feed flow rate, higher catalyst bed height, and higher H₂O₂ dosage are beneficial to m-cresol degradation. Lower pH can also improve m-cresol degradation, but it will cause severe iron leaching. The highest m-cresol removal (over 99.5%) and total organic carbon (TOC) removal (53.6%) can be observed under condition of 2 cm bed height, flow rate of 2 mL/min, reaction temperature of 70 °C, 6 g/L H₂O₂, and initial pH = 1. Meanwhile, the Fe₂O₃-CNT-MF catalyst shows good stability with less than 10% decrease in m-cresol conversion and 7% decrease in TOC conversion after 24-h reaction and less than 2 mg/L iron leaching is observed in all conditions except for strong acid condition. Two probable pathways of m-cresol degradation process are presented. Under most conditions, m-cresol will first be turned into methylhydroquinone, followed by oxidation to p-toluquinone. In basic condition, some m-cresol will first be changed into 4-methylpyrocatechol. These aromatic intermediates will then be oxidized into some small molecular acids and finally be mineralized to CO₂ and H₂O.

25686. 题目: Effects of char from biomass gasification on carbon retention and nitrogen conversion in landfill simulation bioreactors
文章编号: N19122301
期刊: Environmental Science and Pollution Research
作者: Wei Peng, Alberto Pivato, Francesco Garbo, Tianfeng Wang
更新时间: 2019-12-23
摘要: The application of char from biomass gasification as a filling material in landfill simulation reactors was investigated to evaluate the effect of char on carbon retention and nitrogen leaching, nitrogen denitrification, and waste stabilization. Landfill simulation columns filled with fine fraction of aged refuse (AR) and solid fraction of digestate (SFD) were used, with two char application methods: embedding a char layer between AR and SFD layers and mixing char with the SFD. The experimental results show that char application increased the biodegradable organic matter content as the respiration index (RI₄) of the mixture char-SFD increased up to 37.7%, which could enhance the heterotrophic denitrification. Moreover, 12.3% of ammonia leaching was avoid by applying the SFD mixed with char. These results indicate that char from biomass gasification poses a significant enhancement on nitrogen and carbon retention which might increase the denitrification capacity of the SFD in the long run. Although high nitrogen removal rates were achieved (up to 23.1 mg N/kg-TS day), the addition of char from biomass gasification has little effect on the nitrate removal.

25687. 题目: Enhanced adsorption performance and governing mechanisms of ball-milled biochar for the removal of volatile organic compounds (VOCs)
文章编号: N19122206
期刊: Chemical Engineering Journal
作者: Wei Xiang, Xueyang Zhang, Kuiqing Chen, June Fang, Feng He, Xin Hu, Daniel C.W. Tsang, Yong Sik Ok, Bin Gao
更新时间: 2019-12-22
摘要: Hickory wood was pyrolyzed at 300 °C, 450 °C, and 600 °C to produce biochars, which were then modified by ball milling. The pristine and ball-milled biochars were used to remove volatile organic compounds (VOCs) including acetone, ethanol, chloroform, cyclohexane, and toluene. Compared with the corresponding pristine one, each ball-milled biochar showed significantly improved structural characteristics. Their specific surface area (SSA) increased by 1.4–29.1 times, average pore size (APS) decreased slightly, and the hydrophilicity and polarity were also enhanced according to the elemental analysis. The adsorption of VOCs by ball-milled biochar increased by 1.3–13.0 folds, and the maximum adsorption capacity of acetone was up to 103.4 mg/g. The adsorption of polar VOCs (acetone, ethanol, and chloroform) onto ball-milled biochars was mainly controlled by surface adsorption process, which was affected by the SSA, APS, and volatile organic matter of the biochars, as well as the properties of the VOCs. The adsorbed VOCs were completely desorbed from the ball-milled biochars at relatively low temperature (≤115.2 °C). Reusability experiments with five adsorption-desorption cycles showed that ball-milled biochar had an excellent reusability for all VOCs. Ball-milled biochars can therefore be used as an effective and regenerable adsorbent for the removal of VOCs.
图文摘要:

25688. 题目: Variability and determinants of soil organic matter under different land uses and soil types in eastern China
文章编号: N19122205
期刊: Soil and Tillage Research
作者: Manman Fan, Rattan Lal, Huan Zhang, Andrew J. Margenot, Jingtao Wu, Pengbao Wu, Liming Zhang, Jingtao Yao, Furong Chen, Chao Gao
更新时间: 2019-12-22
摘要: Assessing the spatial and temporal variability of soil organic matter (SOM) and identifying determinants of its stability are crucial to measure carbon (C) sequestration and emissions and to understand the evolution of soil functionality. In this study, a spatially dense dataset (5207 topsoil samples (0−20 cm) based on a 1 × 1 km grid) was used to produce SOM maps using geostatistical interpolation by kriging methods and to identify the determinants of SOM distribution in an intensive agricultural region of eastern China. The SOM contents were relatively low and ranged from 10 to 20 g kg⁻¹ for 96.6 % of the total study area, indicating low-fertility soil conditions in the study area. Compared with historical soil data, the SOM content differed among different counties, and increased in most parts of Changfeng and Feidong County from 1981 to 2003. The SOM content was significantly impacted by altitude, aspect, pH, soil texture, as well as soil type and land use, but not by slope gradient, topographic wetness index (TWI) or normalized difference vegetation index (NDVI). The increased application of chemical fertilizer and organic manure in paddy and vegetable-based systems likely contributed to SOM accrual during the 22-year period. Agricultural land uses of paddy rice (Oryza sativa) and vegetable production are conductive to soil C sequestration in agricultural soils in eastern China.

25689. 题目: Nitrogen transformation processes and gaseous emissions from a humic gley soil at two water filled pore spaces
文章编号: N19122204
期刊: Soil and Tillage Research
作者: E. Clagnan, S.A. Rolfe, S.F. Thornton, D. Krol, K.G. Richards, G. Lanigan, P. Tuohy, O. Fenton
更新时间: 2019-12-22
摘要: The artificial drainage of heavy textured gley soils is prevalent on pasture. Drainage of a soil profile reduces the water filled pore space (WFPS) in the upper soil horizons with consequences for N₂ and N₂O emissions, the fate of nitrogen (N), transformational processes and microbial and bacterial communities. The present intact soil column study with isotopically enriched fertiliser investigates all these aspects simultaneously under two WFPS treatments (80% (HS) and 55% (LS) saturation). Results showed significant differences in nitrous oxyde (N₂O) emissions, in both pattern and amount, with maxima at 11.97 mg N₂O-N/m²h for HS and at 1.64 for LS. Isotopic enrichment data showed a significant predominance (74.8–97.2%) of nitrification in LS, with a possible reduction in NH₄⁺ but a higher concentration of nitrate (NO₃⁻) in N losses. Denitrification dominated in HS (72.5–73.4%), possibly leading to high ammonium (NH₄⁺) losses. Enrichment values showed differential apportionment patterns. A high component of N₂O emission derived from denitrification in HS (6.0% HS; 0.4% LS) with a significant amount of N₂O (62.9%) transformed to N₂ (3.7% LS). A higher percentage of ¹⁵N was retained in LS soil. HS showed a lower amount of unaccounted N highlighting lower losses. Differences in gene copy concentrations (GCC) were found across most analysed genes (16S, nirS, nirK, nosZ1, nosZ2, amoA and nrfA). Both HS and LS treatments showed similar potentials for N₂O production and its reduction to N₂, but a reduced potential for nitrification and dissimilatory nitrate reduction to ammonium (DNRA) in HS. This study explained the effect of drainage and rewetting on gaseous emissions providing an explanation in terms of community switches. On the current soil type, structures to manage watertable heights would push the system towards complete denitrification with only N₂ production but may present risks in terms of ammonia (NH₃) and NH₄⁺ losses.

25690. 题目: Immobilization and sorption of Cd and Pb in contaminated stagnic anthrosols as amended with biochar and manure combined with inorganic additives
文章编号: N19122203
期刊: Journal of Environmental Management
作者: Yasir Hamid, Lin Tang, Bilal Hussain, Muhammad Usman, Muhammad Laeeq ur Rehman Hashmi, Muhammad Bilal Khan, Xiaoe Yang, Zhenli He
更新时间: 2019-12-22
摘要: The present study evaluated the efficiency of pre-selected composite amendments (CA-1: biochar-lime-sepiolite-zeolite and CA-2: manure-lime-sepiolite) for immobilization and sorption of Cd and Pb in field and batch sorption experiments. The field experiment was performed in a co-contaminated clay purple soil (stagnic anthrosols). Along with a control experiment (T1), CA-1 and CA-2 were tested at different rates including 750, 1500, 3000 and 6000 kg ha⁻¹ by growing wheat as the test crop. The obtained results revealed that the highest dose of both composites (T5: 6000 kg ha⁻¹ and T9: 6000 kg ha⁻¹) increased the soil pH to 6.85 and 6.81, respectively as compared to the control (5.63). DTPA-extractable Cd and Pb contents decreased with composite treatments (T7 and T4) at harvest stage samples. Metal fractionation depicted that application of amendments decreased the exchangeable fraction at harvesting stage. Application of CA-2 and CA-1 (3000 kg ha⁻¹) significantly increased the plant biomass (by 28% and 24%, respectively) and grain yield (by 26% and 22%, respectively) of wheat. Furthermore, batch sorption experiment results revealed that Langmuir adsorption model better fitted the sorption results with R² values ranging between 0.99 and 0.91 for Cd and Pb, respectively. CA-1 and CA-2 exhibited the maximum adsorption capacity for Cd with no significant difference among treatments but Pb adsorption capacity was highest in CA-1 followed by CA-2 and control. The results of our experiments revealed that the application of organics combined with inorganic materials enhanced Cd and Pb immobilization and sorption, consequently reducing metals availability in laboratory and field conditions. Moreover, for field trials, application of the composite amendments at 3000 kg ha⁻¹ emerged as the suitable treatment for tested wheat-grown area.
图文摘要:

25691. 题目: Studying the relationship between total organic carbon and soil carbon pools under different land management systems of Garo hills, Meghalaya
文章编号: N19122202
期刊: Journal of Environmental Management
作者: Gaurav Mishra, Avishek Sarkar
更新时间: 2019-12-22
摘要: The contribution of land uses in sequestering soil carbon (C) is a key question of research in tropical regions, where C emissions due to land use changes, extreme rainfall events and high temperatures can aggravate the global issue of climate change. In the present study, different pools of soil organic C were assessed, from shifting cultivation lands (jhum), rubber, tea garden and coffee plantations of Tura district in Meghalaya, which is located in Northeastern region (NER) of India. To achieve this goal, different parameters such as bulk density (BD), total organic carbon (TOC) and C pools, viz., very labile (C_VL), labile (C_L), less labile (C_LL) and non-labile (C_NL) were analyzed. The results indicated significant correlations among TOC and C pools in most land uses, except for C_NL pool. Tea gardens showed the highest value of TOC stock (62.75 ± 1.47 t C ha⁻¹) while the lowest was found in the jhum lands (33.34 ± 5.04 t C ha⁻¹). Similarly, both the active (12.03 mg g⁻¹) and passive (4.60 mg g⁻¹) C pools were highest under tea gardens. C_VL was found to be positively correlated with TOC and active carbon pool (ACP), while C_LL was also positively correlated with passive carbon pool (PCP). This study indicates the potential of tea gardens as a promising C sequestering land use, which can be promoted in jhum lands to mitigate the negative impacts of climate change.

25692. 题目: Variations of surface soil δ¹³C_org in the different climatic regions of China and paleoclimatic implication
文章编号: N19122201
期刊: Quaternary International
作者: Dongliang Zhang, Yunpeng Yang, Min Ran
更新时间: 2019-12-22
摘要: Knowledge of relationships between organic carbon isotope composition (δ¹³C_org) of surface soils and climatic factors (precipitation and temperature) is very crucial to reconstruct the paleoclimate variations. Relationships relating δ¹³C_org and climatic factors remain relatively different in the regions influenced by various climatic systems. In this study, based on compiled 1394 surface soil δ¹³C_org data in China, the relationship between soil δ¹³C_org and precipitation and temperature are statistically investigated in the different climatic regions of China (i.e., Xinjiang region, Tibetan Plateau, northern China and southern China). The result show that, spatially, surface soil δ¹³C_org values in Xinjiang region are mainly controlled by temperature and precipitation, while that are mainly controlled by precipitation in Tibetan Plateau. Surface soil δ¹³C_org in northern China and in southern China are mainly influenced by temperature but with a contrary picture. Temporally, a decrease of Holocene δ¹³C_org in Xinjiang region was caused by reducing temperature and increasing precipitation, while an increase of δ¹³C_org in Tibetan Plateau was a response to reducing precipitation. A decrease of Holocene δ¹³C_org in northeast China resulted from temperature decreasing and that in Loess Plateau from temperature decreasing and C₄ abundance reducing. In southern China, temperature decreasing since Holocene was responsible for an increasing trend of δ¹³C_org sequence. Our results can be considered as a basis for the past climate and vegetation interpretation of δ¹³C_org data inferred from various geological archives in the different climatic regions of China.

25693. 题目: Molecular Understanding of Humic Acid-Limited Phosphate Precipitation and Transformation
文章编号: N19122120
期刊: Environmental Science & Technology
作者: Xinfei Ge, Lijun Wang, Wenjun Zhang, Christine V Putnis
更新时间: 2019-12-21
摘要: Phosphorus (P) availability is widely assumed to be limited by the formation of metal (Ca, Fe, or Al) phosphate precipitates that are modulated by soil organic matter (SOM), but the SOM–precipitate interactions remain uncertain because of their environmental complexities. Here, we present a model system by quantifying the in situ nanoscale nucleation kinetics of calcium phosphates (Ca-Ps) on mica in environmentally relevant aqueous solutions by liquid-cell atomic force microscopy. We find that Ca-P precipitate formation is slower when humic acid (HA) concentration is higher. High-resolution transmission electron microscopy observations demonstrate that HA strongly stabilizes amorphous calcium phosphate (ACP), delaying its subsequent transformation to thermodynamically more stable phases. Consistent with the formation of molecular organo–mineral bonding, dynamic force spectroscopy measurements display larger binding energies of organic ligands with certain chemical functionalities on HA to the initially formed ACP than to mica that are responsible for stabilization of ACP through stronger HA–ACP interactions. Our results provide direct evidence for the proposed importance of SOM in inhibiting Ca-P precipitation/transformation. We suggest that similar studies of binding strength in SOM–Fe/Al–P may reveal how both organic matter and metal ions control P availability and fate, and thus the eventual P management for agronomical and environmental sustainability.

25694. 题目: Combination of sunlight with hydrogen peroxide generated at a modified reticulated vitreous carbon for drinking water disinfection
文章编号: N19122119
期刊: Journal of Cleaner Production
作者: Yanchao Jin, Yijun Shi, Ziyu Chen, Riyao Chen, Xiao Chen, Xi Zheng, Yaoxing Liu
更新时间: 2019-12-21
摘要: Long treatment times limit the application of solar disinfection (SODIS). The concentrations of electrolytes in drinking water are low, so it is difficult to generate a sufficient quantity of H2O2 for drinking water disinfection via electrochemical reduction. In this study, SODIS and electrochemical reduction were combined together. A reticulated vitreous carbon (RVC) cathode was anodised to improve its performance and characterized using scanning electron microscopy and X-ray photoelectron spectroscopy. The contributions of the electrochemical process and SODIS to disinfection were studied. The influences of current, temperature and humic acid (HA) were also investigated. The results showed that the modification of RVC added oxygen-bearing functional groups and doubled the quantity of H2O2 generated at the cathode. When the hybrid process was employed to remove E. coli from water, The E. coli count was reduced from approximately 106 colony-forming units (CFUs) per mL to below the detection threshold (<4 CFU/mL) after 120 min. The disinfection time of the hybrid method was lower than those of SODIS and electrochemical disinfection alone by 60% and 20%, respectively. Increasing the current reduced the treatment time from 150 to 90 min, although the treatment consumed more electricity. HA in a low concentration (1 mg/L) could enhance the disinfection process. However, a relatively high HA concentration (4 mg/L) suppressed the inactivation of E. coli. Increasing the temperature from 20 to 40 °C reduced the treatment time from 120 to 90 min, and the electricity consumption per log of E. coli decreased from 102.2 to 64 Wh/m3. This study demonstrates that combining SODIS and H2O2 electrogeneration is an effective and energy-efficient disinfection strategy.

25695. 题目: Hydrogenated TiO2 membrane with photocatalytically enhanced anti-fouling for ultrafiltration of surface water
文章编号: N19122118
期刊: Applied Catalysis B: Environmental
作者: Lei Zhang, Tze Chiang Albert Ng, Ximeng Liu, Qilin Gu, Yajun Pang, Zhixiao Zhang, Zhiyang Lyu, Zeming He, How Yong Ng, John Wang
更新时间: 2019-12-21
摘要: A supported Ti3+ self-doped anatase TiO2 membrane is developed by facile partial-sintering and hydrogenation, and its photocatalytically enhanced anti-fouling in ultrafiltration of surface water is explored. The hydrogenated membranes demonstrate much enhanced photocatalytic activity towards humic acid (HA) degradation, and better anti-fouling capability as compared to the pristine TiO2 membrane. Upon UV irradiation, the hydrogenated TiO2 membrane (TiO2_H30, by 30 h of hydrogenation) shows 60% higher HA removal efficiency, compared with pristine TiO2. During subsequent filtration tests, the TiO2_H30 membrane with UV pre-treatment shows a 50% enhancement of residue normalized flux over that of pristine TiO2, and a tripling of residue normalized flux as compared to tests performed without UV pre-treatment. The enhanced fouling resistance of the hydrogenated TiO2 membranes is directly correlated to the boosted photocatalytic activity, which is attributed to the improved carrier trapping, inhibited recombination, and improved conductivity, due to the hydrogenation-induced surface disorder and Ti3+ self-doping.

25696. 题目: A diverse uncultivated microbial community is responsible for organic matter degradation in the Black Sea sulfidic zone
文章编号: N19122117
期刊: Environmental Microbiology
作者: Saara Suominen, Nina Dombrowski, Jaap S. Sinninghe Damsté, Laura Villanueva
更新时间: 2019-12-21
摘要: Organic matter degradation in marine environments is essential for the recycling of nutrients, especially under conditions of anoxia where organic matter tends to accumulate. However, little is known about the diversity of the microbial communities responsible for the mineralization of organic matter in the absence of oxygen, as well as the factors controlling their activities. Here, we determined the active heterotrophic prokaryotic community in the sulfidic water column of the Black Sea, an ideal model system, where a tight coupling between carbon, nitrogen and sulfur cycles is expected. Active microorganisms degrading both dissolved organic matter (DOM) and protein extracts were determined using quantitative DNA stable isotope probing incubation experiments. These results were compared with the metabolic potential of metagenome assembled genomes obtained from the water column. Organic matter incubations showed that groups like Cloacimonetes and Marinimicrobia are generalists degrading DOM. Based on metagenomic profiles the degradation proceeds in a potential interaction with members of the Deltaproteobacteria and Chloroflexi Dehalococcoidia. On the other hand, microbes with small genomes like the bacterial phyla Parcubacteria, Omnitrophica and of the archaeal phylum Woesearchaeota, were the most active, especially in protein‐amended incubations, revealing the potential advantage of streamlined microorganisms in highly reduced conditions. This article is protected by copyright. All rights reserved.

25697. 题目: Carbon export and drivers in the southeastern Levantine Basin
文章编号: N19122116
期刊: Deep Sea Research Part II: Topical Studies in Oceanography
作者: Ronen Alkalay, Olga Zlatkin, Timor Katz, Barak Herut, Ludwik Halicz, Ilana Berman-Frank, Yishai Weinstein
更新时间: 2019-12-21
摘要: In this paper, we present C export data from the southeastern Levantine Basin, 50 km west of Haifa, at water depth of 1,500 m. Particulate organic carbon (POC) fluxes were measured for 18 months by automated and single bottle sediment traps at the recently-deployed DeepLev observatory and compared with water column profiles of 234Th. Calculations, based on POC/234Th ratios, result in water column-integrated export of 18 mmolC m−2 d−1 at the end of summer (Dec 2017) and remineralization during spring (e.g. 14.4 mmolC m−2 d−1, Apr, 2018). Based on the sediment traps POC export in the basin was generally low (0.05–1 mmolC m−2 d−1 at the base of the photic zone during Dec 2017–May 2018). Fluxes were quite variable, and the export pattern was mainly controlled by coastal discharge or shelf-resuspension (winter peaks) rather than by marine primary production. This was demonstrated by: i) larger POC fluxes measured by deep water (1,300 m) and twilight zone (280 m) traps compared to fluxes measured at the base of euphotic zone, ii) tight correlation of POC with total mass flux, iii) decrease of the POC percentage during winter peak events and iv) imbalance (large integrated deficit or excess) of water column 234Th. Both deficit and excess are evidence of lateral flux, where the first probably results from wave-induced shelf resuspension of organic-poor material, which underwent minimal remineralization and induced scavenging, while the latter derives from the conveyance of large amount of land-derived organic matter, which undergoes remineralization, therefore input of 234Th to the water column.

25698. 题目: Enhanced light‐absorption of black carbon in rainwater compared with aerosols over the northern Indian Ocean
文章编号: N19122115
期刊: Journal of Geophysical Research: Atmospheres
作者: Krishnakant Budhavant, August Andersson, Henry Holmstrand, Poonam Bikkina, Srinivas Bikkina, S.K. Satheesh, Örjan Gustafsson
更新时间: 2019-12-21
摘要: Black carbon (BC) aerosols affect climate, especially in high aerosol loading regions such as South Asia. A key uncertainty for the climate effects of BC is the evolution of light‐absorbing properties in the atmosphere. Here, we present a year‐round comparison of the mass absorption cross‐section (MAC, 678nm) of BC in air (PM10) and rain, for samples collected at the Maldives Climate Observatory at Hanimaadhoo (MCOH). We develop a filter‐loading correction scheme for estimating BC absorption on filters used in high‐volume samplers. The year‐round average MAC678 of BC in the rain is almost twice (13.3 ± 4.2 m2/g) compared to the PM10 aerosol (7.2 ± 2.6 m2/g). A possible explanation is the elevated ratio of organic carbon (OC) to BC observed in rain particulate matter (9.4 ± 6.3) compared to in the aerosols (OC/BC 2.6 ± 1.4, Water‐insoluble organic carbon/BC 1.2 ± 0.8), indicating a coating‐enhancement effect. In addition to BC, we also investigated the MAC365 of water‐soluble Brown Carbon (BrC) in PM10 (0.4 ± 0.4 m2/g, at 365nm). In contrast to BC, MAC365‐BrC relates to air mass history, showing higher values for samples from air originating over the South Asian landmass. Furthermore, calculated washout ratios are much lower for BC compared to OC and inorganic ions such as sulfate, implying a longer atmospheric lifetime for BC. The wet deposition flux for BC during the high loading winter was three times higher than during the wet summer, despite much less precipitation in the winter.

25699. 题目: From Andes to Amazon: assessing branched tetraether lipids as tracers for soil Organic Carbon in the Madre de Dios River system
文章编号: N19122114
期刊: Journal of Geophysical Research: Biogeosciences
作者: Frédérique M.S.A. Kirkels, Camilo Ponton, Valier Galy, A. Joshua West, Sarah J. Feakins, Francien Peterse
更新时间: 2019-12-21
摘要: We investigate the implications of upstream processes and hydrological seasonality on the transfer of soil OC from the Andes mountains to the Amazon lowlands by the Madre de Dios River (Peru), using branched glycerol dialkyl glycerol tetraether (brGDGT) lipids. The brGDGT signal in Andean soils (0.5‐3.5 km elevation) reflects air temperature, with a lapse rate of ‐6.0 °C km^‐1 elevation (r² = 0.89, p<0.001) and ‐5.6 °C km^‐1 elevation (r²=0.89, p<0.001) for Organic and Mineral horizons respectively. The same compounds are present in river suspended particulate matter (SPM) with a lapse rate of ‐4.1 °C km^‐1 elevation (r²=0.82, p<0.001) during the wet season, where the offset in intercept between the temperature lapse rates for soils and SPM indicates upstream sourcing of brGDGTs. The lapse rate for SPM appears insensitive to an increasing relative contribution of 6‐methyl isomer brGDGTs produced within the river. River depth profiles show that brGDGTs are well mixed in the river and are not affected by hydrodynamic sorting. BrGDGTs accumulate relative to OC downstream, likely due to the transition of particulate OC to the dissolved phase and input of weathered soils towards the lowlands. The temperature‐altitude correlation of brGDGTs in Madre de Dios SPM contrasts with the Lower Amazon River, where the initial soil signature is altered by changes in seasonal in‐river production and variable provenance of brGDGTs. Our study indicates that brGDGTs in the Madre de Dios River system are initially soil‐derived, and highlights their use to study OC sourcing in mountainous river systems.

25700. 题目: Contribution of plant litter and soil variables to organic carbon pools following tropical forest development after slash‐and‐burn agriculture
文章编号: N19122113
期刊: Land Degradation & Development
作者: Shaojun Wang, Minkun Chen, Run Cao, Qianbin Cao, Qianqian Zuo, Ping Wang, Bo Yang, Shuang Zhao
更新时间: 2019-12-21
摘要: Tropical forest development after slash‐and‐burn agriculture crucially affects soil carbon accumulation. However, it remains unclear how the dynamics of soil organic carbon pools are regulated following tropical forest restoration. Our study aims to quantify the contribution of litter and soil variables to alterations in carbon pools during tropical forest restoration on slash‐and‐burn agricultural land in Xishuangbanna, Yunnan, China. This study observed a significant increase in soil carbon pools along forest restoration. The extent of the increase in labile fractions (1.9–2.5 times) was higher than that of soil organic carbon (1.5 times) during the restoration from early to later stages. The proportion of microbial carbon to total carbon increased from 3.0% to 7.7% during forest restoration, while those of dissolved (5.3% to 3.1%) and readily oxidizable (42.9% to 29.6%) fractions decreased. Clay content determined the accumulation dynamics of soil organic carbon (10.5%) and labile fractions (6.0–13.5%) in the later stage, while free Fe oxides (10.4–15.4%) contributed to these pools mainly in the early stage. Microbial carbon explained 22.4–26.7% and 20.6–28.3% of the variation in soil organic carbon stocks and labile fractions, respectively, whereas litter carbon accounted for 9.5–15.3% of the change in microbial carbon stock. The contribution (8.2–17.1%) of litter‐soil nutrient interactions to carbon pools increased during forest restoration. Our data suggest that carbon dynamics are mainly determined by variations in the clay content, free Fe oxides, and litter and microbial carbon, possibly through nutrient‐level interactions between the litter and soil during tropical forest restoration.