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24781. 题目: Soil fungal community assembly processes under long‐term fertilization
文章编号: N19101305
期刊: European Journal of Soil Science
作者: Y. Shi, K. K. Dang, Y. H. Dong, M. M. Feng, B. R. Wang, J. G. Li, H. Y. Chu
更新时间: 2019-10-13
摘要: Understanding the processes that regulate communities of microorganisms is a key issue and focus in microbial ecology. Although fungi play a critical role in soil biogeochemical cycling, their community assembly processes remain largely unknown, especially in agricultural soils. In this study, we investigated the relative importance of five community assembly processes: variable selection, homogeneous selection, homogeneous dispersal, dispersal limitation, and undominated process on soil fungal communities under long‐term (28 years, 1990‐2018) fertilization management consisting of 12 different treatments in triplicate field plots. Using Illumina MiSeq sequencing of the 18S rRNA eukaryotic gene, we observed that fungal communities in manure treatments were all structured primarily by homogeneous dispersal, while the communities in chemical fertilizer treatments were structured primarily by homogeneous dispersal and undominated process. Soil calcium played an important role in shaping soil fungal community, while soil organic matter concentrations showed a considerable impact on the soil fungal phylogenetic community composition. Overall, our results suggest that fertilization management should be considered as a key factor driving microbial community assembly processes in farmed soils.

24782. 题目: Evaluating the effect of biochar on mesophilic anaerobic digestion of waste activated sludge and microbial diversity
文章编号: N19101304
期刊: Bioresource Technology
作者: Bo Wu, Qi Yang, Fubing Yao, Shengjie Chen, Li He, Kunjie Hou, Zhoujie Pi, Huanyu Yin, Jing Fu, Dongbo Wang, Xiaoming Li
更新时间: 2019-10-13
摘要: This study compared the effects of sewage sludge-derived pyrochar (PC300, PC500, and PC700) and hydrochar (HC180, HC240, and HC300) on mesophilic anaerobic digestion of waste activated sludge (WAS). It was demonstrated that hydrochar can better promote the methane production compared with pyrochar. The highest accumulative methane yield of 132.04 ± 4.41 mL/g VS_added was obtained with HC180 addition. In contrast, the PC500 and PC700 showed a slightly negative effect on methane production. Sludge-derived HC not only accelerated the solubilization and hydrolysis of sludge floc, but also improved the production of acetic acid and propionate, further resulting in improved methane production. Simultaneously, the syntrophic microbes facilitating direct interspecies electron transfer (DIET) such as Syntrophomonas, Peptococcaceae, Methanosaeta and Methanobacterium bred rapidly with the addition of HCs. These results indicated that the hydrochar is more ideal as the accelerant to promote the methane production from mesophilic anaerobic digestion of WAS than the pyrochar.

24783. 题目: Impact factors of dissolved organic carbon and the transport in a river-lake continuum in the Tibet Plateau of China
文章编号: N19101303
期刊: Journal of Hydrology
作者: Zhidan Wen, Kaishan Song, Ge Liu, Yingxin Shang, Junbin Hou, Lili Lyu, Chong Fang
更新时间: 2019-10-13
摘要: As a significant fraction of carbon in inland waters, dissolved organic carbon (DOC) plays a crucial role in carbon cycling at a global scale. Understanding the linkages between variations in DOC and its dominant factors in lakes is critical for estimating its concentration on a larger scale. This study characterized the concentrations of DOC in the lakes of Tibet Plateau and explored the major underlying influencing factors. The overall mean concentration of DOC in these closed lakes had a mean value of 21.80 ± 30.82 mg/L (mean ± S.D.) and was higher than open lakes (F = 174.1, p < 0.05). The potential drivers for the concentration of DOC in the lakes of Tibet Plateau were conducted by the correlation analysis of DOC with the observed landscape, water quality variables, and climatic factors. The multiple regression model showed that 78% of DOC concentrations across the lakes could be explained by Shannon evenness index (SHEI) of landscape, slope, and landscape dominance index (LDI), of which SHEI explained the most substantial variations for the concentration of DOC. The changes in the concentrations of DOC in river-lake interaction were analyzed in Qinghai Lake watershed. The concentration of DOC in the Qinghai Lake water was higher than the surrounding rivers. Slope and the density of soil organic matter (SOM) in the Qinghai Lake watershed were responsible for the higher DOC in lake than rivers. The landscape had a significant influence on DOC in the lakes, and the dominant factor was SHEI. The results observed from this investigation further supplement the information of DOC in the inland waters with plateau lakes. Further, this study is expected to improve the understanding of the transport of DOC in the river-lake ecosystem.

24784. 题目: Characterization of chromophoric dissolved organic matter in lakes across the Tibet-Qinghai Plateau using spectroscopic analysis
文章编号: N19101302
期刊: Journal of Hydrology
作者: Kaishan Song, Sijia Li, Zhidan Wen, Lili Lyu, Yingxin Shang
更新时间: 2019-10-13
摘要: Fluorescent dissolved organic matter (FDOM) has a significant influence on global inland water carbon cycling and biogeochemical processes. The alpine lakes on Tibet-Qinghai Plateau (TQP) are exposed to high-intensity ultraviolet radiation, long retention time with less anthropogenic influences. Yet, limited studies were conducted on FDOM of lakes on the highest plateau in the world with unique aquatic environments. Spatiotemporal variations of FDOM components from 63 lakes (32 fresh lakes, N = 135; 31 brackish lakes, N = 109) were grouped according to salinity across the TQP collected during 2014–2017. FDOM were examined using excitation-emission matrix spectra (EEM) and fluorescence regional integration (FRI). CDOM absorption and FDOM fluorescence indices, average fluorescence intensities of the five fluorescent components (φ_i, i = I, II, III, IV, V) and total fluorescence intensities (φ_T) are significantly different between brackish and freshwater lakes (p < 0.05). High correlations (−0.51^** < r < −0.86^**, p < 0.01) were revealed between FDOM and dissolved organic carbon (DOC) concentrations with salinity > 10‰. A comparatively prolonged retention time and terrestrial allochthonous inputs caused higher DOC accumulation in brackish water. Strong UV radiation resulted in an important effect on CDOM photo-absorption characteristics, and that contributed to DOC variability and fate. Likewise, average CDOM spectroscopic indices in each basin with different land covers showed a moderate correlation between DOC and normalized humic-like φ_V for 20 basins (r = −0.46^**, p < 0.01). The results suggest that studies on the highest alpine lakes across the TQP should focus on the impact of the evapo-concentration, ultraviolet irradiance and landscape features within different basins on FDOM characteristics. It demonstrated that the FDOM was dominated by the allochthonous sources in brackish lakes from the TQP and had a similarity to those observed in marine environments.

24785. 题目: Potentially toxic elements and biochemical components in surface sediments of NW Mexico: An assessment of contamination and trophic status
文章编号: N19101301
期刊: Marine Pollution Bulletin
作者: Américo Iadran Torres, José Roberto Rivera Hernández, Erica Giarratano, Mauricio Faleschini, Carlos René Green Ruiz, Mónica Noemí Gil
更新时间: 2019-10-13
摘要: Concentrations of Potentially Toxic Elements (PTEs) were determined in sediments from Santa María La Reforma (SAMARE) coastal lagoon and Mocorito River, Mexico. Furthermore, biochemical composition of organic matter in sediments was analyzed to assess their trophic status. The PTEs concentrations followed the order Fe > Pb ∼ Zn > Cr ∼ Cu > Ni ∼ As ∼ Co > Cd. Except for As, PTEs showed correlation between them indicating a common source. As and Pb were above the threshold levels of toxic effect, but they did not exceed the levels of probable effect for biota. Metals were correlated with carbohydrates and As with lipids. Low protein/carbohydrate ratios suggest that decomposed detritus of nitrogen-rich algae as well as fresh mangrove litter can be present. These biochemical proxies suggest that meso-oligotrophic conditions prevail in SAMARE. Considering that fishing activities are practiced and that the northern portion of SAMARE was classified as a RAMSAR site, the information presented is useful to generate strategies for the management of this ecosystem.

24786. 题目: Methyl chloride produced during UV₂₅₄ irradiation of saline water
文章编号: N19101207
期刊: Journal of Hazardous Materials
作者: Qian Yang, Yang Guo, Yue E, Sanbing Zhang, Ernest R. Blatchley, Jing Li
更新时间: 2019-10-12
摘要: Ultraviolet (UV) irradiation is widely used for water treatment due to its effectiveness against a wide range of waterborne pathogens with minimal production of regulated disinfection byproducts. However, in this study, the formation of methyl chloride (CH₃Cl) from guaiacol and chloride was observed during UV₂₅₄ irradiation. The results indicated that direct photolysis of guaiacol produced an arenium ion, and the reactive methoxy group was further transformed to CH₃Cl in the presence of chloride. O-quinone was detected as the primary product of the degradation of guaiacol resulting from UV₂₅₄ irradiation. Other organic compounds containing methoxy, ethoxy, or methylamino groups with structures that are similar to guaiacol were also demonstrated to generate halocarbons in aqueous chloride or bromide solution under UV₂₅₄ irradiation. Scavenging experiments and removal of oxygen demonstrated that neither oxygen nor chlorine radicals were involved in CH₃Cl formation. In seawater samples, CH₃Cl was also detected in the presence or absence of added organic matter. These results demonstrate that CH₃Cl can be formed during UV₂₅₄ irradiation in saline water and that attention should be paid to this compound and structurally-related compounds in the application of UV₂₅₄ processes.
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24787. 题目: Tracking spatio-temporal dynamics of POC sources in eutrophic lakes by remote sensing
文章编号: N19101206
期刊: Water Research
作者: Jie Xu, Shaohua Lei, Shun Bi, Yunmei Li, Heng Lyu, Jiafeng Xu, Xiaoguang Xu, Meng Mu, Song Miao, Shuai Zeng, Zhubin Zheng
更新时间: 2019-10-12
摘要: Estimating the proportions of particulate organic carbon (POC) endmembers is essential to fully understand the carbon cycle, the function of aquatic ecosystems, and the migration of contaminants in eutrophic lakes. There is currently no effective remote sensing optical algorithm in the literature to solve this problem. In this study, a POC-source color index (S_POC) was constructed based on the terrestrial and endogenous POC ratios calculated from field-measured stable isotope (δ¹³C_POC) values. The S_POC algorithm traces the sources of POC by utilizing three spectral bands centered approximately at 560 nm, 674 nm, and 709 nm, covering the intrinsic optical information of different POC sources. At the same time, the S_POC algorithm shows good applicability to Ocean and Land Color Instrument (OLCI), Medium-Resolution Imaging Spectrometer (MERIS), Moderate Resolution Imaging Spectroradiometer (MODIS), and Geostationary Ocean Color Imager (GOCI) image data. The POC sources estimated using the algorithm and monthly OLCI data showed that from March 2018 to January 2019, the POC at the surface of Lake Taihu was mainly terrigenous. In addition, due to multiple factors such as algal blooms, plant physiology, river transport, regional rainfall, and carbon cycling, the distribution of POC sources exhibited strong spatial and temporal heterogeneity. Compared with other methods, it is more convenient to use remote sensing to identify the proportion of POC in different endmembers, which offers a more comprehensive understanding of the energy flows and material circulation in lakes.
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24788. 题目: Impact of organic and inorganic carbon on the formation of nitrite during the VUV photolysis of nitrate containing water
文章编号: N19101205
期刊: Water Research
作者: Mengqi Han, Madjid Mohseni
更新时间: 2019-10-12
摘要: Nitrite formation during Vacuum UV (VUV) photolysis of nitrate-containing water has been studied in this research. Here the goal was to understand the effect of water matrix, specifically dissolved organic carbon (DOC), dissolved inorganic carbon (DIC) and dissolved oxygen (DO), on the formation of nitrite in nitrate-containing water during treatment with VUV AOP. The results confirmed that the formation of nitrite was considerable during the VUV irradiation, and it increased with increasing the UV fluence. However, the rate of nitrite formation was not linearly correlated with the UV fluence. Also, nitrite formation increased with increasing the DOC in water. Tert-butanol, as OH radical scavenger, was used to elucidate the mechanism behind the impact of DOC. The effect of DIC was only pronounced at very high DIC concentration, which led to lower formation of nitrite. When both DOC and DIC were present in water, DOC had the dominant effect on nitrite formation. DO in water had the impact of reducing the formation of nitrite. All these results can help to understand the mechanisms involved in the transformation of nitrate to nitrite in various water matrices, and guide VUV applications for scientific and industrial proposes.
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24789. 题目: The carbonic anhydrase activity of sinking and suspended particles in the North Pacific Ocean
文章编号: N19101204
期刊: Limnology and Oceanography
作者: Adam V. Subhas, Jess F. Adkins, Sijia Dong, Nick E. Rollins, William M. Berelson
更新时间: 2019-10-12
摘要: The enzyme carbonic anhydrase (CA) is crucial to many physiological processes involving CO₂, from photosynthesis and respiration, to calcification and CaCO₃ dissolution. We present new measurements of CA activity along a North Pacific transect, on samples from in situ pumps, sediment traps, discreet plankton samples from the ship's underway seawater line, plankton tows, and surface sediment samples from multicores. CA activity is highest in the surface ocean and decreases with depth, both in suspended and sinking particles. Subpolar gyre surface particles exhibit 10× higher CA activity per liter of seawater compared to subtropical gyre surface particles. Activity persists to 4700 m in the subpolar gyre, but only to 1000 m in the subtropics. All sinking CA activity normalized to particulate organic carbon (POC) follows a single relationship (CA/POC = 1.9 ± 0.2 × 10⁻⁷ mol mol⁻¹). This relationship is consistent with CA/POC values in subpolar plankton tow material, suspended particles, and core top sediments. We hypothesize that most subpolar CA activity is associated with rapidly sinking diatom blooms, consistent with a large mat of diatomaceous material identified on the seafloor. Compared to the basin‐wide sinking CA/POC relationship, a lower subtropical CA/POC suggests that the inventory of subtropical biomass is different in composition from exported material. Pteropods also demonstrate substantial CA activity. Scaled to the volume within pteropod shells, first‐order CO₂ hydration rate constants are elevated ≥ 1000× above background. This kinetic enhancement is large enough to catalyze carbonate dissolution within microenvironments, providing observational evidence for CA‐catalyzed, respiration‐driven CaCO₃ dissolution in the shallow North Pacific.

24790. 题目: Sargassum sp. act as a Large Regional Source of Marine Dissolved Organic Carbon and Polyphenols
文章编号: N19101203
期刊: Global Biogeochemical Cycles
作者: Leanne C. Powers, Norbert Hertkorn, Natasha McDonald, Philippe Schmitt‐Kopplin, Rossana Del Vecchio, Neil V. Blough, Michael Gonsior
更新时间: 2019-10-12
摘要: Dissolved organic carbon (DOC) plays critical roles in marine carbon cycling, but its sources and sinks remain uncertain. In this study, we monitored DOC exudation rates of Sargassum natans under visible light (λ >390 nm) and solar radiation. DOC release rates ranged from 7 to 10 μg C g^‐1_biomass h^‐1 (wet weight) under visible light, but increased to 23 to 41 μg C g^‐1_biomass h^‐1 when exposed to natural sunlight. Results indicate that DOC released by Sargassum could amount to 0.3 to 1.2 Tg C yr^‐1, potentially contributing significantly to the marine DOC pool in the Gulf of Mexico and Western North Atlantic. We employed the Folin‐Ciocalteu phenolic content method, nuclear magnetic resonance (NMR) spectroscopy, and ultrahigh resolution Fourier transform ion cyclotron resonance mass spectrometry (FT‐ICR MS) to characterize the diverse pool of organic compounds exuded from Sargassum. Results from these complementary methods showed that Sargassum release large quantities of phlorotannins, a class of polyphenols that have very similar properties to terrestrial DOC. These phlorotannins and their oxygenated phenolic derivatives exhibit a high hydrogen deficiency and functionalization (i.e. 4 to 6 oxygen atoms per aromatic ring), representing 5 to 18% of the released DOC isolated by solid phase extraction. Thus, Sargassum is the largest biological source of open ocean polyphenols recorded to date. The amount of polyphenolic DOC released by Sargassum challenges previous beliefs that all polyphenols found within the oceans are remnants of terrestrial organic matter, although the stability of phlorotannins and their derivatives needs to be further evaluated.

24791. 题目: Almond and walnut shell-derived biochars affect sorption-desorption, fractionation, and release of phosphorus in two different soils
文章编号: N19101202
期刊: Chemosphere
作者: Narges Hemati Matin, Mohsen Jalali, Vasileios Antoniadis, Sabry M. Shaheen, Jianxu Wang, Tao Zhang, Hailong Wang, Jörg Rinklebe
更新时间: 2019-10-12
摘要: Effective soil phosphorus (P) management requires higher level of knowledge concerning its sorption-desorption, fractionation, and release, as well as its interactions with soil amendments including biochar (BC). The purpose of this research was to investigate the influence of two different BCs, derived from almond and walnut shell, on P sorption-desorption and its redistribution among the geochemical fractions in two different soils. The BCs were applied to the soils in four doses (0, 2.5, 5, and 10% w/w) and the mixtures were incubated for one month. Phosphorus sorption increased due to the addition of BCs. Phosphorus sorption data fitted well the Freundlich isotherm and were simulated by the PHREEQC software. Biochar addition increased total P and the added P was mainly distributed in the exchangeable, Fe/Al–P and the residual fractions. Also, BC addition resulted in an increase in the water-soluble-, mobile-, and Olsen-P, making P more available for plant uptake. The kinetics data were well described by the simple Elovich, pseudo-second-order, and intra-particle diffusion equations. Walnut BC-added soils had higher P sorption capacity than those added with the almond BC. The results suggest that BC binds soil P and releases it gradually back into solution, making it thus available to plants; this renders the studied BCs promising materials for protecting P from being lost out of soil. Future research must be conducted over longer-term experiments that would study P dynamics in BC-added soils under real field conditions.
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24792. 题目: Persulfate activation by sulfide-modified nanoscale iron supported by biochar (S-nZVI/BC) for degradation of ciprofloxacin
文章编号: N19101201
期刊: Separation and Purification Technology
作者: Jie Gao, Dongqiang Han, Yun Xu, Yingying Liu, Jingge Shang
更新时间: 2019-10-12
摘要: Antibiotics ciprofloxacin pollution has become a major problem in the aqueous environment. Advanced oxidation processes (AOP) have been recognized as promising technology to treat wastewater contaminated by antibiotics. In this study, biochar-supported sulfided nanoscale zero- valent iron (S-nZVI/BC) was employed as a catalyst to activate persulfate (PS) to remove the ciprofloxacin (CIP). The effects of S/Fe molar ratio, PS dosage, initial pH value and CIP concentration, and coexisting anion were investigated. Results showed that S-nZVI/BC exhibited excellent performance in removing CIP when combined with PS. S-ZVI/BC with an S/Fe mole ratio of 0.25 exhibited the highest CIP removal efficiency. CIP could be efficiently removed when the initial solution pH ranged from 2.5 to 8.5, and chloride was found to have a negative effect on degradation. The batch experimental data agreed well with the pseudo-second-order model. Radical scavenger studies revealed that SO₄^•− and HO^• were the crucial reactive species, which contributed to the high CIP degradation performance. A possible degradation pathway was proposed with the elimination of the piperazine ring based on the LC-MS analysis. Moreover, the catalytic ability of S-nZVI/BC could be maintained at 87 % after five turnovers. In all, this study indicates that S-nZVI/BC is an ideal catalyst for PS activation for antibiotics treatment.
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24793. 题目: Effect of additional food waste slurry generated by mesophilic acidogenic fermentation on nutrient removal and sludge properties during wastewater treatment
文章编号: N19101105
期刊: Bioresource Technology
作者: Jialing Tang, Yunhui Pu, Xiaochang C. Wang, Yisong Hu, Jin Huang, Huu Hao Ngo, Shengwang Pan, Yuyou Li, Nengmin Zhu
更新时间: 2019-10-11
摘要: Fermentation slurry from food waste (FSFW) generated by acidogenic fermentation at mesophilic temperature was utilized to improve the nutrients removal from wastewater. Organic acids (such as lactate and volatile fatty acids) in the FSFW behaved as readily biodegradable carbon sources, while the particulate and macromolecular organics acted as slowly biodegradable carbon sources during denitrification processes. The FSFW dosage significantly influenced the nitrogen removal performance, and a C/N ratio (in terms of chemical oxygen demand to nitrogen ratio) of 8 could achieve complete denitrification in the batch tests. In a sequencing batch reactor (SBR) using FSFW for long-term wastewater treatment, extracellular polymeric substances (EPS) gradually accumulated, sludge particle size significantly increased, and microbial communities were selectively enriched, which contributed to promoting the nitrogen (>80%) and phosphate (90.1%) removal efficiencies. Overall, the FSFW produced by acidogenic fermentation under mesophilic temperature served as an excellent intermediary between FW valorization and wastewater treatment.
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24794. 题目: Mechanism of negative surface charge formation on biochar and its effect on the fixation of soil Cd
文章编号: N19101104
期刊: Journal of Hazardous Materials
作者: Zhongxin Tan, Shengnan Yuan, Mengfan Hong, Limei Zhang, Qiaoyun Huang
更新时间: 2019-10-11
摘要: The studies of the mechanism of Cd fixation by biochar have mainly focused on the pore size, pH, and oxygen-containing functional groups, and few researches have paid close attention to the effect of the negative charge in biochar surface. In this paper, biochar was produced in the CO₂ atmosphere at different pyrolysis temperatures, and the influence of the pyrolysis temperature on biochar surface charge were explored. The cause of the negative charge on the biochar surface has been analysed, and the optimal preparing temperature for the biochar with the best effect of cadmium immobilization from soil has been found. The results show that with the increasing temperature from 300 to 700 °C, the negative surface charge on biochar surface gradually decreases, while the fixed amount of Cd increases. The factors affecting the surface charge of biochar are ash content, pH, oxygen-containing functional groups, polar groups, and hydrogen bonds. Among them, the pH, oxygen-containing functional groups and polar groups have positive effects on the surface negative charge, whereas the hydrogen bond has a negative effect. The determinant of surface charge is the hydroxyl group, the content of hydroxyl group decreases as increasing temperature, resulting in a decrease in surface negative charge.

24795. 题目: Carbon and nutrient fluxes from seagrass and mangrove wrack are mediated by soil interactions
文章编号: N19101103
期刊: Estuarine, Coastal and Shelf Science
作者: Joshua L. Breithaupt, Evan Duga, Megan Witt, Rebecca Filyaw, Noah Friedland, Melinda J. Donnelly, Linda J. Walters, Lisa G. Chambers
更新时间: 2019-10-11
摘要: Shoreline accumulation of vegetative wrack may contribute nutrient subsidies for primary or secondary production, detritivore food-web support, habitat provision, and sediment stabilization. This study addresses a knowledge gap in the literature by going beyond quantification of carbon (C) and nutrient flux potentials to investigate the biogeochemical interaction between wrack and shoreline soil. Results from a year-long shoreline survey of wrack type and abundance in Mosquito Lagoon, FL, were combined with a two-month intact core experiment observing the interaction of mangrove and seagrass leaves with organic and mineral shoreline soils. Experimental treatments were subjected to tidal cycles; at low tide, measurements were made of soil respiration and drainage water nutrient content. A measure called Soil Interaction with Litter Effect (SoILE) is introduced to quantify the suppression or enhancement of C and nutrient fluxes from a combination of wrack with shoreline soils compared to the potential fluxes of wrack and soil separately.Monthly mean (±1 S.E.) accumulation of wrack dry mass in Mosquito Lagoon was 37.65 ± 2.99 g m⁻². Unusually high values (72.16 ± 13.74 g m⁻²) occurred in September 2017 following Hurricane Irma. In a comparison of seagrass and mangrove leaves and organic and mineral soils, seagrass leaves were the greatest source of dissolved inorganic nitrogen (DIN) and soluble reactive phosphorus (SRP) by factors of 24 and 13, respectively. Seagrass also had the highest fluxes of dissolved organic carbon (DOC) and CO₂ by factors of 2 and 2.7, respectively. The most common effect of combining wrack and soil was to suppress the magnitude of DOC and CO₂ fluxes. There were few differences between combined and additive fluxes of DIN and SRP; the DIN flux was suppressed from the combination of seagrass with organic soil, and the SRP flux was enhanced from the combination of mangrove leaves with mineral soil. Suppression and enhancement of SoILE values were likely both attributable to a “smothering” effect caused by the physical interaction of vegetation with the soil surface that altered redox conditions. Wrack accumulation on restored living shorelines is likely to have a two-fold positive effect of subsidizing nutrients for primary production by shoreline plants and contributing to an increase in soil carbon by interacting with soils to result in a net suppression of DOC and CO₂ effluxes.
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24796. 题目: Synthesis and characteristics of a novel FeNi 3 /SiO 2 /TiO 2 magnetic nanocomposites and its application in adsorption of humic acid from simulated wastewater: study of isotherms and kinetics
文章编号: N19101102
期刊: Environmental Science and Pollution Research
作者: Fateme Akbari, Maryam Khodadadi, Ayat Hossein Panahi, Ali Naghizadeh
更新时间: 2019-10-11
摘要: The presence of natural organic matter such as humic acid in water creates various problems in water purification. Humic acid can react with chlorine in the disinfection step and lead to the production of trihalomethanes and haloacetic acids that these compounds have carcinogenic and mutagenic properties; therefore, they must be removed before arriving to the disinfection stage. The purpose of this research was adsorption of humic acid from simulated wastewater by synthesized FeNi₃/SiO₂/TiO₂ magnetic nanocomposites. FeNi₃/SiO₂/TiO₂ magnetic nanocomposites were synthesized by sol-gel procedure and its characteristics were determined by TEM, VSM, BET, FESEM, and XRD techniques. Then, the effects of such pH (3–11), FeNi₃/SiO₂/TiO₂ dosage (0.005–0.1 g/L), contact time (0–200 min), and initial concentration (2–15 mg/L) were studied on humic acid adsorption using FeNi₃/SiO₂/TiO₂. The results of adsorption experiments revealed that the highest percentage of humic acid removal (94.4%) was achieved at pH 3, initial concentration of 5 ppm, FeNi₃/SiO₂/TiO₂ dose of 0.1 g/L, and contact time of 90 min. The analyses of experimental isotherm data showed that the humic acid adsorption was described by Langmuir model and also the kinetic studies represented that the process of adsorption of humic acid on FeNi₃/SiO₂/TiO₂ was followed by the pseudo-second kinetic. According to the results, it can be concluded that FeNi₃/SiO₂/TiO₂ magnetic nanocomposites have a high ability to absorb humic acid from simulated wastewater.

24797. 题目: Applicability of advanced oxidation processes in removing anthropogenically influenced chlorination disinfection byproduct precursors in a developing country
文章编号: N19101101
期刊: Ecotoxicology and Environmental Safety
作者: Surbhi Tak, Bhanu Prakash Vellanki
更新时间: 2019-10-11
摘要: The studies on occurrence of contaminants of emerging concern in drinking water treatment plants or even wastewater treatment plants in developing country like India, are very limited. Trihalomethanes (THMs) is one such contaminant of concern in drinking water treatment sector. THMs are the major disinfection byproducts (DBPs) formed during the widely used chlorination process. Their identification and removal is of utmost importance in developed as well as developing nations. This study is first of its kind to assess the removal of mixture of urban run-off driven organic matter, agricultural run-off driven organic matter, untreated sewage effluent driven organic matter and little natural organic matter (NOM) (altogether NefOM) (major DBP precursors) using advanced oxidation processes (AOPs) in the Indian region. Since, NOM vary geographically, this study will add up to applicability of generally utilized AOPs for removal of site explicit (Indian) NefOM. Trihalomethanes at a conventional water treatment plant at Mathura and a moving bed biofilm based non-conventional water treatment plant at Agra were monitored over a year, demonstrating the inability of the water treatment plants to limit formation of DBPs from Yamuna inlet water at any time of the year. Various AOPs (UV–H₂O₂, O₃–H₂O₂, O₃) and UV (ultraviolet) photolysis were assessed for their ability to decrease the trihalomethane forming potential (THMFP) by degrading the contaminants in the waters of Yamuna. Kinetic studies were conducted to evaluate the selected AOPs based on their ability to mineralize dissolved organic carbon (DOC), and decrease UV₂₅₄ at various pH, UV intensities, and ozone and hydrogen peroxide concentrations. UV-L/H₂O₂ at an intensity of 47 mJ/cm²/min, pH = 7, and at hydrogen peroxide concentration of 0.5 mM provided an optimum reduction of DOC (64%) and UV₂₅₄ (87%). Fractionation studies indicated that treatment by UV-L/H₂O₂ leads to the most significant decrease in the hydrophobic fraction of the water, while further study indicated that UV-L/H₂O₂ also showed maximum attenuation of THMFP.
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24798. 题目: Photochemical Aging of Soot in the Aqueous Phase: Release of Dissolved Black Carbon and the Formation of 1 O 2
文章编号: N19101007
期刊: Environmental Science & Technology
作者: Meng Li, Fengxia Bao, Yue Zhang, Hua Sheng, Chuncheng Chen, Jincai Zhao
更新时间: 2019-10-10
摘要: The photochemical aging of soot in the aqueous phase could have an important influence on water environments such as fog water and wet aerosols in the atmosphere, as well as lakes and oceans. In this study, we systematically investigated the photochemistry of soot in the aqueous phase. Soot releases dissolved black carbon into the aqueous phase during photoreactions, which is attributed to the phototransformation of the nonpolar unsaturated C–H species in soot to polar carbonyl-containing species. More importantly, we found that soot suspensions, particularly those of the dissolved part of soot, were effective photosensitizers for the generation of singlet oxygen (1O2). The 1O2 apparent quantum yield of the dissolved part reached 33 ± 2% under 377 nm irradiation, which is an order of magnitude higher than those of most types of well-studied dissolved organic matter in water. As a result, soot could impact the environmental fate of coexisting organic contaminants, such as the photodegradation of bisphenol A. This study will not only give insight into the photochemistry of soot in the liquid phase but also reveal the significant implications of soot photoaging in the aqueous phase by the release and degradation of organic matter.

24799. 题目: Wintertime Optical Properties of Primary and Secondary Brown Carbon at a Regional Site in the North China Plain
文章编号: N19101006
期刊: Environmental Science & Technology
作者: Qiyuan Wang, Jianhuai Ye, Yichen Wang, Ting Zhang, Weikang Ran, Yunfei Wu, Jie Tian, Li Li, Yaqing Zhou, Steven Sai Hang Ho, Bo Dang, Qian Zhang, Renjian Zhang, Yang Chen, Chongshu Zhu, Jun-ji Cao
更新时间: 2019-10-10
摘要: The light-absorbing properties of atmospheric brown carbon (BrC) are poorly understood due to its complex chemical composition. Here, a black-carbon-tracer method was coupled with source apportionments of organic aerosol (OA) to explore the light-absorbing properties of primary and secondary BrC from the North China Plain (NCP). Primary emissions of BrC contributed more to OA light absorption than secondary processes, and biomass burning OA accounted for 60% of primary BrC absorption at λ = 370 nm, followed by coal combustion OA (35%) and hydrocarbon-like OA (5%). Secondary BrC absorption was high in the early morning and later decreased due to the bleaching of chromophores. Nighttime aqueous-phase chemistry promoted the formation of secondary light-absorbing compounds and the production of strongly absorbing particles. Source analysis showed that the NCP region was the most important source for primary and secondary BrC subtypes at the study site. The mean direct radiative forcing for BrC was 0.15 W m–2 (0.11 W m–2 and 0.04 W m–2 for the primary and secondary fractions, respectively). This study provides new information on the optical properties of primary and secondary BrC and highlights the importance of atmospheric oxidation on BrC absorption.

24800. 题目: Retention of microplastics in sediments of urban and highway stormwater retention ponds
文章编号: N19101005
期刊: Environmental Pollution
作者: Fan Liu, Alvise Vianello, Jes Vollertsen
更新时间: 2019-10-10
摘要: Urban and highway surfaces discharge polluted runoff during storm events. To mitigate environmental risks, stormwater retention ponds are commonly constructed to treat the runoff water. This study is the first to quantify the retention of microplastics in the sediments of such ponds. It applied state-of-art FTIR-methods to analyse the composition, size, shape, and mass of microplastics in the range 10–2000 μm. Seven ponds serving four land uses were investigated, and the results are related to catchment characteristics, sediment organic matter content, and hydraulic loading. We have not found a correlation between the microplastics abundance, polymer composition, size distribution and the land use in the catchment, as well as the sediment organic matter content. Both the highest (127,986 items kg⁻¹; 28,732 μg kg⁻¹) and the lowest (1511 items kg⁻¹; 115 μg kg⁻¹) accumulation of microplastics were found in the sediments of ponds serving industrial areas. There was, however, a correlation to the hydraulic loading of the ponds, where the sediments of the highest-loaded ponds held the most microplastics. This study shows that sediments in stormwater retention ponds can trap some of the microplastics and prevent them from being transported downstream. These systems need to be considered when assessing the fate of microplastics from urban and highway areas.
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