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25201. 题目: Arctic soil carbon turnover controlled by experimental snow addition, summer warming and shrub removal
文章编号: N19122102
期刊: Soil Biology and Biochemistry
作者: Nynne R. Ravn, Bo Elberling, Anders Michelsen
更新时间: 2019-12-21
摘要: Northern latitude tundra heaths have accumulated large amounts of organic carbon (C) in the soil. Changes in climatic conditions such as temperature and winter precipitation might affect the C balance and potentially change these tundra ecosystems from being C sinks to sources of CO₂ emitted to the atmosphere. However, studies on C fluxes with single and combined winter snow and summer warming effects are scarce. This study investigates gross ecosystem production (GEP), ecosystem respiration (ER), net ecosystem production (NEP) and carbon isotopic composition of CO₂ emitted from a dry heath in arctic Greenland one and two years following field manipulations of summer temperature, shrub abundance and winter snow depth. Our aims were to quantify climatic change effects on CO₂ fluxes and the growing season carbon balance of the ecosystem and to investigate shifts in δ¹³C of emitted CO₂ potentially due changes in emission from old soil C versus recently fixed carbon. Ecosystem CO₂ fluxes and δ¹³C-CO₂ were measured using closed chambers, and soil CO₂ concentrations and δ¹³C were measured depth-specifically using gas probes.We found a significant increase of CO₂ emissions in all treatments during both years. Growing season NEP increased by 38 and 73% with 1 m enhanced winter snow depth, by 113 and 144% with summer warming and by 61 and 320% with total shrub removal in 2013 and 2014, respectively. The snow effect can be explained by the delay in the onset of growth as indicated by early season reduced vegetation greenness. The effect of warming was a result of an increase of ER by 39 and 32%, and the effect of shrub removal was mainly due to a reduction in GEP by 34 and 48%, in 2013 and 2014, respectively. Furthermore, the δ¹³C of the carbon source of CO₂ emitted from warmed plots increased significantly two years after the experiment was initiated. This might indicate increased decomposition of ¹³C enriched soil organic matter and hence increased mineralization of the old carbon stock in the soil under warmed conditions. The increase of NEP, the additive response of all treatments, and the indications of increased emission of carbon from old stocks due to warming (or warming-induced drying), demonstrate the risk of a relatively fast feedback to climate warming during the snow-free season.
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25202. 题目: In-situ determination of current density distribution and fluid modeling of an electrocoagulation process and its effects on natural organic matter removal for drinking water treatment
文章编号: N19122101
期刊: Water Research
作者: Sean T. McBeath, Amin Nouri-Khorasani, Madjid Mohseni, David P. Wilkinson
更新时间: 2019-12-21
摘要: Electrocoagulation is a burgeoning technology now being considered for niche water treatment applications. Although much research has been conducted to determine the efficacy of electrocoagulation to remove various contaminants, the more fundamental electrochemical aspects of the technology are often overlooked. This research provides insight into the fundamental relationship of water flow, electrochemical metal dissolution and current density distribution through computational fluid dynamic (CFD) models, mathematical models and in-situ current density distribution identification experiments. Theoretically, it was determined that current distributed along the electrode was inversely proportional to the water flowrate. The turbulent flow through the EC reactor was simulated with varying inter-electrode gaps and flowrates, while the average velocity segments across the electrode surface was calculated, corresponding to the same segments used to experimentally determine the current distribution. Through the CFD models and current distribution determining technique, it was observed that current density was distributed unevenly and followed the trend predicted by theory. Areas of lower current density were generally accompanied by higher velocity flow. More uniform current was yielded with larger inter-electrode gaps, due to the greater flow uniformity. While operating with a 1 mm gap, the current and water velocity varied across the electrode by Δ27.6 mA/cm² and Δ0.220 m/s, and was minimized to Δ3.6 mA/cm² and Δ0.062 m/s at a 10 mm gap. Although current uniformity was increased, the overall current density decreased significantly due to the greater ohmic resistance associated with the larger gap. The removal of natural organic matter was reduced as much as 79% when the inter-electrode gap was reduced from 10 to 1 mm.
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25203. 题目: Relationship between macro‐pores and soil organic carbon fractions under long‐term organic manure application
文章编号: N19122011
期刊: Land Degradation & Development
作者: Lingying Xu, Meiyan Wang, Yutian Tian, Xuezheng Shi, Yijie Shi, Quanbo Yu, Shengxiang Xu, Jinhua Pan, Xiangwei Li, Xinqiao Xie
更新时间: 2019-12-20
摘要: Greenhouse vegetable production systems converted from cereal fields often experience a decrease in soil aeration due to intensive land use. Organic fertilization is a method commonly used to solve this problem. While previous studies have considered soil organic carbon (SOC) or soil pores under organic cultivation, the relationship between SOC fractions and soil macro‐pores is unknown. This study analysed the long‐term progressive variations in soil macro‐pore (>50 μm) and SOC fraction characteristics in organic greenhouse vegetable plantations (one‐year‐old, nine‐year‐old, and fourteen‐year‐old fields) converted from rice‐wheat rotation fields and established the relationship with X‐ray computed tomography scanning and ¹³C solid‐state nuclear magnetic resonance spectroscopy. The results suggested that the total macro‐porosity increased from 7.95% to 16.36% throughout the whole organic plantation, and a similar trend occurred in small (50‐500 μm) and medium (500‐1000 μm) macro‐porosity. Besides, the total SOC content and the contents of its fractions increased with organic planting time. With the total macro‐porosity exhibiting significant associations with SOC (r = 0.81*^*), the relative proportion of O‐alkyl C (r = ‐0.94*^*) and the relative proportion of aromatic C (r = 0.89*^*), a lower O‐alkyl C proportion of SOC might help to increase macro‐porosity. A similar relationship was found between the relative proportion of SOC fractions and the macro‐porosity. The O‐alkyl C proportion had significantly negative relations with aromatic C (r = ‐0.94*^*) and SOC (r = 0.84*^*). Overall, both SOC and its fractions can help to improve soil macro‐porosity, but the effects of different fractions on these pores vary.

25204. 题目: Towards simple tools to assess functional effects of contaminants on natural microbial and invertebrate sediment communities
文章编号: N19122010
期刊: Environmental Science and Pollution Research
作者: Stéphane Pesce, Sophie Campiche, Carmen Casado-Martinez, Ayanleh Mahamoud Ahmed, Chloé Bonnineau, Aymeric Dabrin, Emilie Lyautey, Benoit J.D. Ferrari
更新时间: 2019-12-20
摘要: Surface sediments can accumulate contaminants that affect microorganisms and invertebrates and disturb benthic ecological functions. However, effects of contaminants on ecological functions supported by sediment communities are understudied. Here, we tested the relevance of two simple tools to assess the ecotoxicological effects of metal contamination on natural sediment communities using particulate organic matter breakdown and decomposition as a functional descriptor. To this aim, we performed a 21-day laboratory microcosm experiment to assess the individual and combined effects of Cu and As (nominal concentration of 40 mg kg⁻¹ dw each) using the bait-lamina method (cellulose, bran flakes, and active coal in PVC strips) as well as artificial tablets (cellulose, bran flakes and active coal embedded in an agar matrix). Sediment toxicity was also evaluated using the standardized ostracod toxicity test. Both the bait-lamina and artificial tablet methods showed low effects of As on organic matter breakdown and decomposition but strong effects of Cu on this important ecological function. Both also showed that the presence of Cu and As in mixture in the sediment induced total inhibition of organic matter breakdown and decomposition. The ostracod toxicity test also showed high toxicity of Cu-spiked and Cu-plus-As-spiked sediments and low toxicity of As-spiked sediments. Besides confirming that artificial organic matter substrates are relevant and useful for assessing the functional effects of contaminants on sediment micro- and macro-organism communities, these results suggest that the proposed methods offer promising perspectives for developing tools for use in assessing functional ecotoxicology in the sediment compartment.

25205. 题目: Organochlorine pesticides and dissolved organic matter within a system of urban exorheic lakes
文章编号: N19122009
期刊: Environmental Monitoring and Assessment
作者: Cristina Liana Popa, Simona Ionela Dontu, Elfrida Mihaela Carstea, Erika Andrea Levei, Cristian Ioja, Ana Maria Popa, Mirela Miclean, Oana Cadar
更新时间: 2019-12-20
摘要: Urban lakes represent the most extensive water bodies in cities and provide blue ecosystem services, by retaining pollutants, offering cultural services, and mitigating climate change. Human activities threaten to decrease the supply of ecosystem services associated with urban lakes. Exorheic lakes play an essential role in reducing and changing the characteristics of pollutants and organic matter along the environmental continuum. This study aims to gain further understanding on the distribution and fate of organochlorine pesticides (OCPs) in relation to fluorescent dissolved organic matter (DOM) within an exorheic lake system, located along Colentina river, Bucharest. Results indicated a historical usage of HCHs, which were present in lake water and sediment samples, in concentrations exceeding the regulatory limits, with potential eco-toxicity on aquatic biota. Decades of intense applications along the river, before OCPs ban, led to their accumulation in sediments and their re-mobilization, each year, after the lakes were drained, dredged, and refilled. Fluorescence measurements revealed that DOM accumulated in certain lakes due to wastewater discharges, and surface runoff, but decreased towards the end of the exorheic lakes through dilution, sedimentation, and biodegradation. The results also showed that fluorescent DOM may have a substantial impact on OCPs cycle in urban lakes and may help to determine the conditions and effectiveness of removing OCPs from water and sediments. These issues contribute to the decrease of ecosystem services supply associated with urban lakes, having multiple hidden consequences on the urban environment.

25206. 题目: The role of direct photolysis in the photodegradation of the herbicide bentazone in natural surface waters
文章编号: N19122008
期刊: Chemosphere
作者: Luca Carena, Debora Fabbri, Monica Passananti, Marco Minella, Marco Pazzi, Davide Vione
更新时间: 2019-12-20
摘要: The photochemical fate of the herbicide bentazone was assessed by lab experiments and modeling tools. Experimental and modeling results showed that bentazone is mainly photodegraded by direct photolysis in natural water samples, even in the presence of dissolved organic matter (DOM) that can act as light-screening agent, photosensitizer and scavenger of reactive species. Even when it was dissolved in natural water samples containing different DOM amounts, the phototransformation kinetics of bentazone was unchanged compared to irradiation runs in ultrapure water. This finding suggests that the DOM and the other components of our samples did not affect the direct photolysis of bentazone by light-absorption competition, at least at the experimental optical path lengths, and did not induce significant indirect photodegradation by producing reactive transient species. Photochemical modeling in a lake-water photoreactivity scenario corroborated the observed experimental results, showing the predominant role of direct photolysis in the overall (direct + indirect) photodegradation of bentazone at different water depths and DOM contents. However, the model predicted a minor but non-negligible contribution of indirect photochemistry (i.e., reactions triggered by HO^•, CO₃^•− and ³CDOM*) to the herbicide degradation. This contribution (especially by ³CDOM*) could become crucial in deep and DOM-rich water bodies. Finally, several photoproducts formed by direct photolysis and HO^•-induced photodegradation were identified, which should not be particularly toxic for aquatic organisms and Vibrio fischeri bacteria.
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25207. 题目: Landscape heterogeneity impacts water chemistry, nutrient regime, organic matter and chlorophyll dynamics in agricultural reservoirs
文章编号: N19122007
期刊: Ecological Indicators
作者: Usman Atique, Kwang-Guk An
更新时间: 2019-12-20
摘要: The objectives of this study were to determine the seasonal and temporal variabilities of nutrients, chlorophyll (Chl-a) and some other parameters in 95 agricultural reservoirs influenced by the Asian monsoon during 2008–2017, and elucidates the links of water chemistry dynamics to landscape heterogeneity. Using the long-term data, we analyzed seasonal and inter-annual patterns of the water quality in relation to the intensity of the summer monsoon and developed the seasonal empirical models on CHL-nutrients (N, P) in relation to the light regime by the calculation of non-algal light attenuation coefficient (K_na). Multi-metric water pollution index (WPI_KR) reflected on the chemical health of reservoirs in relation to monsoon and land use patterns. The results divulged the intensity of monsoon rainfall tremendously influenced nutrients, Chl-a and TOC level in cropland and urban regions. TP showed the highest percentage of relationship with Chl-a and ambient nutrient ratios indicating it as the limiting factor particularly in cropland, urban and forest region. TOC disclosed the highest relationship with Chl-a in cropland (R² = 0.66) and forest (R² = 0.71) regions. Secchi disk depth (SDD) displayed a strong negative relationship with suspended solids, TP and Chl-a in cropland and estuarine regions. K_na indicated a strong relationship with TP and TOC in cropland and estuarine region reservoirs. On the other hand, trophic state index specified the majority of reservoirs in zooplankton grazing state except few in the estuarine region showing the propensity of blue-green algae presence. Further principal component analysis (PCA) designated cropland region characterized by higher TP and Chl-a level within increasing Carlson’s trophic state index (CTSI), the urban region receiving higher sediments and chemical oxygen demand. On the contrary, the forest region showed a tendency of higher organic matter (TOC) while estuarine characterized by higher electrical conductivity (EC). Hierarchical cluster analysis (HCA) showed that cropland region reservoirs strongly linked to urban reservoirs in terms of deteriorating water quality. Based on WPI_KR results, cropland and urban region reservoirs reflected as ‘poor’, estuarine as ‘fair’ condition while forest region indicated ‘excellent to good’ chemical health status. According to CTSI, forest and estuarine reservoirs were in the oligotrophic state, urban in mesotrophic and cropland region reservoirs from mesotrophic to eutrophic state. This study supports a reduction in phosphorus yielding fertilizers in the Korean Peninsula that could lead to eutrophication of lentic ecosystems in the future along with mitigation of anthropogenic impacts in the reservoir's watershed.
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25208. 题目: Primordial organic matter in the xenolithic clast in the Zag H chondrite: Possible relation to D/P asteroids
文章编号: N19122006
期刊: Geochimica et Cosmochimica Acta
作者: Yoko Kebukawa, Michael E. Zolensky, Motoo Ito, Nanako O. Ogawa, Yoshinori Takano, Naohiko Ohkouchi, Aiko Nakato, Hiroki Suga, Yasuo Takeichi, Yoshio Takahashi, Kensei Kobayashi
更新时间: 2019-12-20
摘要: Some xenolithic clasts in meteorites may have originated from unique primitive Solar System bodies. These clasts would provide novel insights into the early evolution of the Solar System. We conducted multiple analyses of organic matter (OM) in a CI-like xenolithic clast in the Zag (H5) meteorite including bulk elemental and isotopic analysis, FTIR, STXM/XANES, and NanoSIMS. The bulk C and N abundances in the Zag clast were +5.1 ± 0.4 wt.% and +0.26 ± 0.01 wt.%, respectively, which were the highest observed among various chondrite groups. The bulk δ¹³C value of the Zag clast was +23.0 ± 4.1 ‰ which was close to the value of the Tagish Lake meteorite; the δ¹⁵N value was +300 ± 3 ‰ which was close to the values of CR chondrites and Bells (a unique CM). The δD values of C-rich regions obtained by NanoSIMS were approximately +600 to +2000‰ which were close to the values of IOM from CI, CM and Tagish Lake. Some isotopic “hot spots” were observed with δD values up to ≈ +4000‰ and δ¹⁵N values up to ≈ +5500‰. The infrared transmission spectrum of the Zag clast was consistent with the abundant phyllosilicates and carbonates observed in the clast. The STXM showed abundant OM in various forms. C-XANES spectra from the OM were generally similar to CI/CM/CR chondrites. However, some variations existed in the molecular structures. OM in the Zag clast was partially associated with carbonates. The functional group, elemental and isotopic signatures of the OM in the Zag clast support the idea that the Zag clast is unique among known carbonaceous chondrite groups and originated from the outer Solar System such as aqueously-altered D/P type asteroids.

25209. 题目: Ultra-low concentration of total organic carbon in ultrapure water using ion-exchange resin embedding silanized magnetic nanoparticles
文章编号: N19122005
期刊: Journal of Environmental Sciences
作者: Jung Joon Lee, Jihyeon Park, Bo-Hyun Kim, Sunjong Lee
更新时间: 2019-12-20
摘要: Regeneration of pure water is an important issue not only for the healthy life but also for the fine control of precise processes in various industries. One important issue in ultra-high purified water is to reduce the amount of total organic carbon (TOC). Herein, we introduce a new approach to reduce the TOC using the surface silanized nanoparticles, in which the magnetic nanoparticles (mNPs) are silanized and then complexed with ion exchange resin (IER) beads. The Fe₃O₄ mNPs are surface modified by using high concentrated vinyltrimethoxysilane (VTMS) and then adhered on the surface of IER beads. The surface modified mNPs have a thick-shell of polysiloxane layer varying from 5 to 22 nm depending on the amount of VTMS used, which leads the significant increase of specific surface area. The IER beads embedding VTMS-silanized mNPs achieves about 7 μg/L of the TOC level in ultrapure water system, which is two orders less than 228 μg/L of the feeding water and one order less than 96 μg/L from the system using pristine IER beads. This result is mainly attributed to the polysiloxane layer forming broccoli-like surface structure and some part by the vinyl group of VTMS exposed to the amines in the water.
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25210. 题目: Soil organic carbon and aggregation in response to thirty-nine years of tillage management in the southeastern US
文章编号: N19122004
期刊: Soil and Tillage Research
作者: Surendra Singh, Amin Nouri, Shikha Singh, Saseendran Anapalli, Jaehoon Lee, Prakash Arelli, Sindhu Jagadamma
更新时间: 2019-12-20
摘要: Agricultural management practices control soil organic carbon (SOC) content in croplands. Long-term cropping system experiments offer a great opportunity to understand the magnitude and direction of SOC change in response to management practices. Such information is very limited from the southeastern US, a region with warm and humid climatic conditions that typically favor SOC decomposition over accumulation. Therefore, this study was conducted to assess the effect of 39 years of chisel plow (CP), disc plow (DP), moldboard plow (MP), no-tillage (NT), NT with winter wheat (Triticum aestivum L.) cover crop (NTW), and NT with wheat-soybean (Glycine max L.) double crop (NTWD) on total SOC and SOC fractions including permanganate oxidizable C (POXC), water extractable C (WEC), resistant C (RC), and aggregate-associated SOC in a continuous soybean system. Additionally, aggregate size distribution, mean weight diameter (MWD), and wet aggregate stability (WAS) were determined. Results showed that NTW and NTWD significantly increased SOC and POXC compared to MP with mean SOC (g kg⁻¹ soil) of 12.2 (NTW) ≥10.9 (NTWD) >7.2 (MP) and mean POXC (mg kg⁻¹ soil) of 465 (NTWD) ≥418 (NTW) >252 (MP). The WEC and RC fractions did not differ among treatments. Across the treatments, the greatest aggregate-associated SOC concentration was found in microaggregates (0.053–0.25 mm) and the lowest in clay- and silt-size particles (<0.053 mm). Additionally, WAS under NT systems was significantly higher (45.5–52.3 %) than under tilled treatments (21.9–29.1 %). Total SOC correlated significantly with POXC (r = 0.68, p < 0.01), RC (r = 0.46, p < 0.05), WAS (r = 0.65, p < 0.01), and aggregate-associated SOC concentrations (r > 0.6, p < 0.01). Overall, this study revealed that NT enhanced SOC and POXC accumulation and macroaggregation compared to tilled treatments. Cover cropping and double cropping further improved SOC accumulation. In conclusion, long-term adoption of different tillage intensities can strongly alter SOC dynamics in bulk soil and aggregates under continuous soybean production systems of the southeastern US.

25211. 题目: Organic nitrogen in residential stormwater runoff: Implications for stormwater management in urban watersheds
文章编号: N19122003
期刊: Science of The Total Environment
作者: Mary G. Lusk, Gurpal S. Toor, Patrick W. Inglett
更新时间: 2019-12-20
摘要: Stormwater runoff containing organic nitrogen (N) is a source of potentially bioavailable N in water bodies. Characterization and concentrations of dissolved organic N (DON) and particulate organic N (PON) in urban stormwater runoff are rarely reported and considered in stormwater management. Our objectives were to (1) characterize the organic (DON, PON) and inorganic (NO₃⁻ and NH₄⁺) N pools in residential stormwater runoff and (2) determine the rainfall driven landscape sources of runoff PON using an isotopic mixing model with ¹³C and ¹⁵N during a wet season (June–September). We instrumented a 13 ha (0.13 km²) residential catchment located in Florida, United States with an ISCO autosampler and collected stormwater runoff samples (n = 52) over 11 individual stormwater runoff events. Mean concentration of total N in runoff during the wet season was 1.61 mg L⁻¹, of which 37% was DON and 25% was PON. A strong seasonal first flush of PON, giving rise to a large PON:TN ratio, was observed as the wet season progressed from June (PON:TN = 0.39;) to September (PON:TN = 0.12), whereas DON did not display any seasonal variability (mean: 0.66 mg L⁻¹). The isotope mixing model estimated that 76% of PON in the runoff originated from oak detritus (leaves: 50%, acorns: 26%) and the remaining 24% from lawn grass clippings. The dominance of organic N fractions in the urban stormwater runoff suggests that landscape controls on PON and DON are needed to reduce N loading in the urban stormwater runoff. The seasonal first flush of PON indicates that monitoring strategies should focus on how nutrient concentrations in runoff may respond to seasonal drivers such as leaf litterfall and that there may be optimal times for N management, such as after a prolonged dry season in which materials accumulate and pose the risk for later mobilization.
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25212. 题目: Aggregation and stability of nanoscale plastics in aquatic environment
文章编号: N19122002
期刊: Water Research
作者: Mehnaz Shams, Iftaykhairul Alam, Indranil Chowdhury
更新时间: 2019-12-20
摘要: The widespread use and release of plastics in nature have raised global concerns about their impact on public health and the environment. While much research has been conducted on macro- and micro-sized plastics, the fate of nanoscale plastics remains unexplored. In this study, the aggregation kinetics and stability of polyethylene and polystyrene nanoscale plastics were investigated over a wide range of aquatic chemistries (pH, salt types (NaCl, CaCl_2, MgCl₂), ionic strength) relevant to the natural environment. Results showed that salt types and ionic strength had significant effects on the stability of both polyethylene and polystyrene nanoscale plastics, while pH had none. Aggregation and stability of both polyethylene and polystyrene nanoscale plastics in the aquatic environment followed colloidal theory (DLVO theory and Schulze-Hardy rule), similar to other colloidal particles. The critical coagulation concentration (CCC) values of polyethylene nanoscale plastics were lower for CaCl₂ (0.1 mM) compared to NaCl (80 mM) and MgCl₂ (3 mM). Similarly, CCC values of polystyrene nanospheres were 10 mM for CaCl₂, 800 mM for NaCl and 25 mM for MgCl₂. It implies that CaCl₂ destabilized both polyethylene and polystyrene nanoscale plastics more aggressively than NaCl and MgCl₂. Moreover, polystyrene nanospheres are more stable in the aquatic environment than polyethylene nanoscale plastics. However, natural organic matter improved the stability of polyethylene nanoscale plastics in water primarily due to steric repulsion, increasing CCC values to 0.4 mM, 120 mM and 8 mM for CaCl_2, NaCl and MgCl₂ respectively. Stability studies with various water conditions demonstrated that polyethylene nanoscale plastics will be fairly stable in the natural surface waters. Conversely, synthetic surface water, wastewater, seawater and groundwater rapidly destabilized polyethylene nanoscale plastics. Overall, our findings indicate that significant aqueous transport of nanoscale plastics will be possible in natural surface waters.
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25213. 题目: Scaling behavior of iron in capacitive deionization (CDI) system
文章编号: N19122001
期刊: Water Research
作者: Tianyu Wang, Changyong Zhang, Langming Bai, Binghan Xie, Zhendong Gan, Jiajian Xing, Guibai Li, Heng Liang
更新时间: 2019-12-20
摘要: This study investigated the fouling and scaling behaviors in a capacitive deionization (CDI) system in the presence of iron and natural organic matter (NOM). It was found that the salt adsorption capacity (SAC) significantly decreased when treating Fe-containing brackish water, with higher Fe concentrations leading to severer SAC reduction. Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) analysis demonstrated that Fe₂O₃ appeared to be the predominant foulant attached on the electrode surface, which was difficult to be removed via backwashing, indicating the irreversible property of the foulant. Further characterizations (e.g., N₂ sorption-desorption isotherms, electrochemical impedance spectroscopy and cyclic voltammetry) revealed that the CDI electrodes suffered from obvious deterioration such as specific surface area loss, resistance increase and capacitance decline with the occurrence of Fe scaling. While the presence of NOM alleviated the Fe scaling through NOM-Fe complexing effects, NOM itself was found to have negative impacts on CDI desalination performance due to their strong interactions with the carbon electrodes.
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25214. 题目: Leaching behavior of Cd, Zn and nutrients (K, P, S) from a contaminated soil as affected by amendment with biochar
文章编号: N19121912
期刊: Chemosphere
作者: Reinhart Van Poucke, Erik Meers, Filip M.G. Tack
更新时间: 2019-12-19
摘要: In Campine region in Flanders (Belgium) there are contaminated sites with Cd and Zn due to atmospheric deposition from industry. Flanders is also known for its large surpluses of nitrogen and phosphorous coming from intense livestock production. To solve both issues, the potential of biochar to sorb metals and nutrients was investigated. Experiments were conducted to examine whether biochar could reduce the leaching of nutrients (K, P and S) and metals (Cd and Zn) into the soil solution. Most biochars caused an increase in pH of approximately 1 unit which is often the main driver of the metal immobilization. Nutrient concentrations in the leachate of soil amended with oak-based biochar were lower compared to the blank soil. For the other amendments, however, the results were higher due to the nutrients leached from the applied products.The result of this experiment emphasize the potential of biochar to immobilize nutrients and metals in soil water systems, thus keeping the nutrients longer available for the plant and reducing the metal toxicity. However, the amount of metals immobilized was lower than expected. Further research is required to determine whether biochar from livestock products could act as a slow release fertilizer.

25215. 题目: Transformation of amino acid tyrosine in chromophoric organic matter solutions: Generation of peroxide and change of bioavailability
文章编号: N19121911
期刊: Chemosphere
作者: Qing Zhoua, Xu Zhang, Chi Zhou
更新时间: 2019-12-19
摘要: Studying the photochemical transformation mechanism of dissolved free amino acids (DFAA) in chromophoric dissolved organic matter (CDOM) solution facilitates the understanding of DFAA’s environmental fate and bioavailability change upon solar irradiation in natural surface waters. Tyrosine oxidation product (Tyr-OH) was synthesized to quantify the primary transformation product (tyrosine peroxide, Tyr-OOH) in CDOM solution. Both reactions between superoxide radical anion (O₂⁻) and tyrosine radical (Tyr) and between singlet oxygen (¹O₂) and tyrosine (Tyr) yield Tyr-OOH, which is subsequently transformed into Tyr-OH. The reaction between O₂⁻ and Tyr not only generated Tyr-OOH but also caused the regeneration of Tyr. O₂⁻ and ¹O₂ contributed 30−44% to Tyr’s transformation in CDOM solutions at pH 8.0, in which ¹O₂ oxidation accounted for 6–11%. The contribution of O₂⁻ to Tyr’s phototransformation process was the difference between the total contribution of O₂⁻ and ¹O₂ and the individual contribution of ¹O₂. Compared with the fast assimilation of Tyr, Tyr-OH was stable in natural water under dark incubation, indicating that phototransformation decreased the bioavailability of Tyr.
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25216. 题目: Humic acid functionalized magnetic nanomaterials for remediation of dye wastewater under ultrasonication: Application in real water samples, recycling and reuse of nanosorbents
文章编号: N19121910
期刊: Chemosphere
作者: Ravindra Kumar Gautam, Ida Tiwari
更新时间: 2019-12-19
摘要: Water pollution by industrial sector is a great problem which hampers the sustainable development goals. Dye containing water effluent poses vast challenge to clean water before its discharge in to the surrounding ecosystem. Herein, we prepared humic acid functionalized Fe₃O₄ nanosorbents through an eco-friendly route and applied for decolorization of carcinogenic dye from water. The nanosorbents was characterized by AFM, BET surface area analyzer, FTIR, SEM-EDX, TEM, TGA/DTG, VSM and XRD. Adsorption experiments were conducted by taking the appropriate amount of dye in different sources of water under ultrasonication. Adsorption process was controlled by chemisorption in nature making pseudo-second-order model most suitable. Multilayer adsorption was taking place on the active sites of nanosorbents showing applicability of Freundlich isotherm model with highest adsorbed amount of 199.986 mg g⁻¹ at 323 K. Rise in temperature favors the remediation of colored effluent thus positive value of ΔH° (74.234 kJ mol⁻¹) and negative value of ΔG° shows endothermic and spontaneous nature of adsorption system. Cationic surfactant CTAB favors the adsorption (<80%) while anionic SDS gives very low removal (>48%) because of the micelle formation at the surface of nanosorbents. Decolorization from real water samples shows that the adsorption of malachite green was 97, 90, 91, 87, and 86% for Ganga river water, tap water, well water, hand pump water and submersible water, respectively. The used Fe₃O₄/HA nanosorbents was easily recycled from water samples through 0.1 M HCl and nanosorbents was used up to five cycles with greater percentage of removal at 85%.
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25217. 题目: Biochar promotes the reduction of N₂O to N₂ and concurrently suppresses the production of N₂O in calcareous soil
文章编号: N19121909
期刊: Geoderma
作者: Wenxu Dong, Anna Walkiewicz, Andrzej Bieganowski, Oene Oenema, Magdalena Nosalewicz, Chaohui He, Yuming Zhang, Chunsheng Hu
更新时间: 2019-12-19
摘要: Biochar additions may mitigate N₂O emissions from soil. The mechanisms underpinning the mitigation of emissions remain to be elucidated. A series of incubation experiments were performed to investigate the effects of biochar on N₂O production and reduction in columns with a low-fertility or high-fertility soil, with or without the injection of N₂O in the subsoil and with and without glucose (to stimulate denitrification). Biochar was added to the calcareous soils in 0 and 1% (w/w) amounts and moisture was maintained at 70% water-filled pore space (WFPS) over the incubation period. The results revealed that biochar reduced the emissions of soil-produced N₂O by 37–47% and those of injected N₂O by 23–44%. The addition of glucose solution strongly increased N₂O emissions, while biochar reduced total N₂O emissions by as much as 64–81% and those of injected N₂O alone by 29–51%. Differences between the low-fertility and high-fertility soils in the apparent N₂O emission mitigation by biochar were relatively small, but tended to be larger for the low-fertility soil. The results suggest that biochar addition can suppress the production of N₂O in soil and simultaneously stimulate the reduction of N₂O to N₂. Further studies are needed to elucidate the regulatory effects of biochar in soil.

25218. 题目: Linking thermogravimetric data with soil organic carbon fractions
文章编号: N19121908
期刊: Geoderma
作者: David Tokarski, Martin Wiesmeier, Helena Doležalová Weissmannová, Karsten Kalbitz, Michael Scott Demyan, Jiří Kučerík, Christian Siewert
更新时间: 2019-12-19
摘要: Different soil fractionation approaches are frequently used to separate soil organic carbon (SOC) pools of different turnover time and shed light on soil carbon dynamics. However, these methods are laborious and time consuming. Thermogravimetry might be an alternative. Previous studies revealed relationships between soil organic matter (SOM), total nitrogen, clay content, and soil respiration and thermogravimetry (TG) data represented by TG indicators (mass loss in 10 °C intervals) and TG fractions (mass loss in larger temperature intervals). In this work, both TG indicators and fractions were correlated with the contents of SOC fractions representing different turnover times. The fractions we used were particulate organic carbon, dissolved organic carbon, organic C in the sand fraction and in stable aggregates, organic C attached to silt and clay particles and a chemically resistant fraction (<63 µm and not oxidizable by NaOCl). Fractionation and thermogravimetry was applied to 144 samples from arable and grassland top- and subsoils. The results revealed that both TG indicators and fractions or their combinations correlated with SOC fractions in grassland topsoils (R² between = 0.70–0.92, p < 0.001 except for the chemically resistant fraction), while the correlation with SOC fractions in arable soils were significantly lower (R² between 0.36 and 0.72, p < 0.001). No correlations were observed between TG data and SOC fractions in subsoils of arable and grassland soils. Importantly, most of the correlations were observed in soils in which carbon content correlated with TG indicator between 340 and 350 °C. This TG indicator can be used as a differentiator for the application of developed equations for modeling the functional SOC fractions of different turnover times in various types of soils. Thermogravimetry is not able to replace classical fractionation schemes. However, the results showed that thermogravimetry can be an additional tool to assess SOM quality in different land use systems besides traditional chemical-physical fractionation methods.

25219. 题目: Simulated photo-degradation of dissolved organic matter in lakes revealed by three-dimensional excitation-emission matrix with regional integration and parallel factor analysis
文章编号: N19121907
期刊: Journal of Environmental Sciences
作者: Jin Zhang, Fanhao Song, Tingting Li, Kefu Xie, Huiying Yao, Baoshan Xing, Zhongyu Li, Yingchen Bai
更新时间: 2019-12-19
摘要: Simulated photo-degradation of fluorescent dissolved organic matter (FDOM) in Lake Baihua (BH) and Lake Hongfeng (HF) was investigated with three-dimensional excitation-emission matrix (3DEEM) fluorescence combined with the fluorescence regional integration (FRI), parallel factor (PARAFAC) analysis, and multi-order kinetic models. In the FRI analysis, fulvic-like and humic-like materials were the main constituents for both BH-FDOM and HF-FDOM. Four individual components were identified by use of PARAFAC analysis as humic-like components (C1), fulvic-like components (C2), protein-like components (C3) and unidentified components (C4). The maximum 3DEEM fluorescence intensity of PARAFAC components C1–C3 decreased by about 60%, 70% and 90%, respectively after photo-degradation. The multi-order kinetic model was acceptable to represent the photo-degradation of FDOM with correlation coefficient (R_adj²) (0.963–0.998). The photo-degradation rate constants (k_n) showed differences of three orders of magnitude, from 1.09× 10⁻⁶ to 4.02 × 10⁻⁴ min⁻¹, and half-life of multi-order model T12n) ranged from 5.26 to 64.01 min. The decreased values of fluorescence index (FI) and biogenic index (BI), the fact that of percent fluorescence response parameter of Region I (P_I,n) showed the greatest change ratio, followed by percent fluorescence response parameter of Region II (P_II,n), while the largest decrease ratio was found for C3 components, and the lowest T12n was observed for C3, indicated preferential degradation of protein-like materials/components derived from biological sources during photo-degradation. This research on the degradation of FDOM by 3DEEM/FRI-PARAFAC would be beneficial to understanding the photo-degradation of FDOM in natural environments and accurately predicting the environmental behaviors of contaminants in the presence of FDOM.
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25220. 题目: Cadalenes and norcadalenes in organic-rich shales of the Permian Irati Formation (Paraná Basin, Brazil): tracers for terrestrial input or also indicators of temperature-controlled organic-inorganic interactions?
文章编号: N19121906
期刊: Organic Geochemistry
作者: Laercio Lopes Martins, Hans-Martin Schulz, Hélio Jorge Portugal Severiano Ribeiro, Caroline Adolphsson do Nascimento, Eliane Soares de Souza, Georgiana Feitosa da Cruz
更新时间: 2019-12-19
摘要: Cadalene, isocadalene and a series of norcadalenes were identified in black shales of the Permian Irati Formation in the northeastern and central eastern Paraná Basin (Brazil). The origin of their α-isomers with an isopropyl substituent is potentially related to higher plants, and likely reflects the spreading of pteridophytes and gymnosperms after the glaciation of southern Gondwana. A general increase in the relative abundance of isocadalene (1,6-dimethyl-3-isopropylnaphthalene, the β-isomer) co-occurs in with increasing thermal maturity at the base of the Amaral Machado Quarry (northeastern basin), and refers to the acid-catalyzed rearrangement of cadalene (1,6-dimethyl-4-isopropylnaphthalene, the α-isomer) due to the presence of montmorillonite, via an organic-inorganic interaction. This localized and incipient maturation can be related to diabase sills of the Serra Geral Formation. Similar maturation due to heating also affected the distribution of the norcadalenes by thermally stabilizing their α-isomers with an isopropyl substituent, in addition to the formation of related compounds with an ethyl substituent. Based on this, a norcadalene ratio is proposed, which is the sum of the 1,6-dimethyl-4-ethylnaphthalene and 1,6-dimethyl-3-ethylnaphthalene over the sum of the 1-isopropyl-4-methylnaphthalene and 1-isopropyl-7-methylnaphthalene. The results of this ratio and the established cadalene ratio resemble each other whereas samples from the São Mateus do Sul Quarry (central eastern basin) were not affected by thermal maturation and are characterized by a uniform distribution of the cadalenes and norcadalenes.