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13321. 题目: Degradation of naphthalene with magnetic bio-char activate hydrogen peroxide: Synergism of bio-char and Fe–Mn binary oxides
文章编号: N19052703
期刊: Water Research
作者: Ling Li, Cui Lai, Fanglong Huang, Min Cheng, Guangming Zeng, Danlian Huang, Bisheng Li, Shiyu Liu, MingMing Zhang, Lei Qin, Minfang Li, Jiangfan He, Yujin Zhang, Liang Chen
更新时间: 2019-05-27
摘要: This study investigated the hydrogen peroxide (H2O2) activation potential of Fe–Mn binary oxides modified bio-char (FeMn/bio-char) for the degradation of naphthalene, the dominant PAHs in drinking water. Results showed that FeMn/bio-char exhibited 80.7- and 2.18-times decomposition rates towards H2O2 than that of pure bio-char and Fe–Mn binary oxides, respectively, and consequently the FeMn/bio-char/H2O2 photo-Fenton system presented highest naphthalene removal efficiency. The enhanced catalytic activity could be ascribed to the synergistic effect of the combination of bio-char and Fe–Mn binary oxides, such as promoting the adsorption capacity towards contaminant, increasing concentration of persistent free radicals (PFRs) and introducing Fe–Mn binary oxides as new activator. According to the batch-scale experiments, FeMn/bio-char/H2O2 photo-Fenton system could degrade naphthalene effectively at a wide pH ranges, and 82.2% of naphthalene was degraded under natural pH of 5.6 within 148 min. Free radicals quenching studies and electron spin resonance (ESR) analyses verified that the dominant free radical within FeMn/bio-char/H2O2 photo-Fenton system was hydroxyl radical (•OH). According to the preliminary analysis, the generation of •OH were ascribed to the activation of H2O2 by Fe (II), Mn (II) and PFRs on the catalyst surface. The mainly degradation intermediates of naphthalene were identified by GC-MS analysis. Consequently, the possible degradation pathways were proposed. Moreover, naphthalene degradation experiments were also conducted in river, tap water, industrial wastewater as well as medical wastewater, and the results indicated that the FeMn/bio-char/H2O2 photo-Fenton system was effective in the treatment of naphthalene in natural waters. This study brings a valuable insight for the potential environmental applications of modified bio-char.
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13322. 题目: Carbon and mercury export from the Arctic rivers and response to permafrost degradation
文章编号: N19052702
期刊: Water Research
作者: Cuicui Mu, Feng Zhang, Xu Chen, Shemin Ge, Mei Mu, Lin Jia, Qingbai Wu, Tingjun Zhang
更新时间: 2019-05-27
摘要: Arctic rivers export a large amount of organic carbon (OC) and mercury (Hg) to Arctic oceans. Because there are only a few direct calculations of OC and Hg exports from these large rivers, very little is known about their response to changes in the active layer in northern permafrost-dominated areas. In this study, multiyear data sets from the Arctic Great Rivers Observatory (ArcticGRO) are used to estimate the export of dissolved organic carbon (DOC), particulate organic carbon (POC), total mercury (THg) and methylmercury (MeHg) from the six largest rivers (Yenisey, Lena, Ob, Mackenzie, Yukon and Kolyma) draining to the Arctic Ocean. From 2003 to 2017, annual DOC and POC export to the Arctic Ocean was approximately 21612 Gg and 2728 Gg, and the exports of Hg and MeHg to the Arctic Ocean were approximately 20090 kg and 110 kg (0.002% of the total Hg stored in the northern hemisphere active layer). There were great variations in seasonal OC and Hg concentrations and chemical characteristics, with higher fluxes in spring and lower fluxes in winter (baseline). DOC and Hg concentrations are significantly positively correlated to discharge, as discharge continues to increase in response to a deepening active layer thickness during recent past decades. This study shows that previous results likely underestimated DOC exports from rivers in the circum-Arctic regions, and both OC and Hg exports will increase under predicted climate warming scenarios.
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13323. 题目: Ash application enhances decomposition of recalcitrant organic matter
文章编号: N19052701
期刊: Soil Biology and Biochemistry
作者: Louise Hindborg Mortensen, Carla Cruz-Paredes, Olaf Schmidt, Regin Rønn, Mette Vestergård
更新时间: 2019-05-27
摘要: Harvesting whole-tree biomass for biofuel combustion intensifies removal of nutrients from the ecosystem. This can be partly abated by applying ash from the combustion back to the system, as the ash is rich in nutrients. Ash is very alkaline and ash application raises soil pH, which in turn can stimulate microbial activity and thus decomposition and mineralization. Our aim was to test if ash induced decomposition activity was associated with enhanced turnover of recalcitrant, i.e. relatively old, organic pools. Two experiments were conducted in the same coniferous plantation after the application of 0, 3, 4.5 and 6 t ash ha−1, and 0, 3, 9, 15 and 30 t ash ha−1, respectively. We used natural abundance of 15N in mosses, mites and ectomycorrhizal fungi 26 months after ash application, as well as temporal variation in δ15N values of ectomycorrhizal fungi, as an indicator of decomposition of recalcitrant organic matter in the first experiment. Furthermore, in the second experiment we used measurements of extracellular manganese peroxidase activity almost 4 years after ash application as an indication of potential decomposition of lignin, an important component of recalcitrant organic matter.The δ15N signature increased significantly for ectomycorrhizal fungi, dead moss, Nothroid and Gamasida mites, and manganese peroxidase activity tended to increase, with increasing ash doses. This suggests that ash application stimulates turnover of recalcitrant organic matter, which can increase the available pool of nitrogen in the system. This will potentially enhance the fertilizer value of ash. However, the δ15N in ectomycorrhizal fungi tended to peak at 18 months after ash application, before decreasing, suggesting that the turnover of recalcitrant organic matter is reduced again with time.
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13324. 题目: The combination of coagulation and ozonation as a pre-treatment of ultrafiltration in water treatment
文章编号: N19052604
期刊: Chemosphere
作者: Fan Bu, Baoyu Gao, Xue Shen, Wenyu Wang, Qinyan Yue
更新时间: 2019-05-26
摘要: Ultrafiltration (UF) technology is considered an efficient water treatment method. In recent years, researchers have been committed to enhancing the treatment efficiency of UF and alleviating membrane fouling. An effective method is to achieve this is through the use of coagulation as a pre-treatment to UF; however, during a long term operation, membrane fouling can occur due to the residual organic matters and the generation of microorganisms. In this study, we combine coagulation and ozonation as a pre-treatment of UF and compare four types of pre-treatment: coagulation, ozonation, coagulation followed by ozonation (C–O) and ozonation followed by coagulation (O–C). Results showed that ozonation alone did not perform well. Both combinations of coagulation and ozonation enhanced the organic matter removal efficiency, although membrane fouling was lowest following the C–O pre-treatment as the microbial load was reduced. While a slight increase in the yield of disinfection by-products was observed with the addition of ozonation, the concentration remained below the Chinese standard for tap water quality (100 μg/L).

13325. 题目: Sequential electrocoagulation-electrooxidation for virus mitigation in drinking water
文章编号: N19052603
期刊: Water Research
作者: Joe Heffron, Donald R. Ryan, Brooke K. Mayer
更新时间: 2019-05-26
摘要: Electrochemical water treatment is a promising alternative for small-scale and remote water systems that lack operational capacity or convenient access to reagents for chemical coagulation and disinfection. In this study, the mitigation of viruses was investigated using electrocoagulation as a pretreatment prior to electrooxidation treatment using boron-doped diamond electrodes. This research is the first to investigate a sequential electrocoagulation-electrooxidation treatment system for virus removal. Bench-scale, batch reactors were used to evaluate mitigation of viruses in variable water quality via: a) electrooxidation, and b) a sequential electrocoagulation-electrooxidation treatment train. Electrooxidation of two bacteriophages, MS2 and ΦX174, was inhibited by natural organic matter and turbidity, indicating the probable need for pretreatment. However, the electrocoagulation-electrooxidation treatment train was beneficial only in the model surface waters employed. In model groundwaters, electrocoagulation alone was as good or better than the combined electrocoagulation-electrooxidation treatment train. Reduction of human echovirus was significantly lower than one or both bacteriophages in all model waters, though bacteriophage ΦX174 was a more representative surrogate than MS2 in the presence of natural organic matter and turbidity. Compared to conventional treatment by ferric salt coagulant and free chlorine disinfection, the electrocoagulation-electrooxidation system was less effective in model surface waters but more effective in model groundwaters. Sequential electrocoagulation-electrooxidation was beneficial for some applications, though practical considerations may currently outweigh the benefits.
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13326. 题目: The characterization of biochars derived from rice straw and swine manure, and their potential and risk in N and P removal from water
文章编号: N19052602
期刊: Journal of Environmental Management
作者: Ling Luo, Guolan Wang, Guozhong Shi, Mengting Zhang, Jing Zhang, Jinsong He, Yinlong Xiao, Dong Tian, Yanzong Zhang, Shihuai Deng, Wei Zhou, Ting Lan, Ouping Deng
更新时间: 2019-05-26
摘要: Nowadays, the plant residual derived biochars have been widely applied to remove nitrogen (N) and phosphorus (P) from water. However, the application of animal manure derived biochars in N and P removal was less studied. To compare the different efficiency and risk of plant residual- and animal manure-derived biochar in removing N and P from water, this study chose rice straw and swine manure as representative to produce biochar at 700 °C, and modified the produced biochar by MgCl2. Then, the characteristics, removal efficiency and release of N and P of biochars were investigated. The results showed swine manure-biochars generally had higher ash content and cation exchange capacity (CEC), but lower pH and surface area relative to rice straw-biochars. Besides, MgCl2 modification reduced the ash content and surface area of both raw biochars, whereas the pH, CEC and pore size were enhanced. Furthermore, this work demonstrated that ammonium and nitrate could be removed by all biochars to certain extent, and MgCl2 modified biochars generally had higher removal efficiency. However, none of phosphate removal was achieved by all biochars. Additionally, the release of ammonium, nitrate and phosphate from biochars was observed, suggesting there might be a risk for applying biochars in N and P removal from water. Notably, the MgCl2 modification seemed to accelerate N and P release from biochars. This work provided important information that the production and modification of biochars should be carefully designed for higher removal efficiency of pollutants. Meanwhile, the risk of released pollutants as well as the release mechanisms should be paid more attention in the future.
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13327. 题目: Crop rotation and succession in a no-tillage system: Implications for CO2 emission and soil attributes
文章编号: N19052601
期刊: Journal of Environmental Management
作者: Clariana Valadares Xavier, Mara Regina Moitinho, Daniel De Bortoli Teixeira, Gustavo André de Araújo Santos, Marcelo de Andrade Barbosa, Débora Marcondes Bastos Pereira Milori, Everlon Rigobelo, José Eduardo Corá, Newton La Scala Júnior
更新时间: 2019-05-26
摘要: This study aimed to quantify and characterize the relationship between soil CO2 emission (FCO2) and soil physical, chemical, and microbiological attributes at the end of the agricultural season in an area under a no-tillage system with crop rotation for more than 16 years. Summer crop sequences consisted of corn and soybean monoculture and corn-soybean rotation. Winter crops were corn, millet, pigeon pea, grain sorghum, and crotalaria. Treatments consisted of combinations of three summer crop sequences with five winter crops. Sixteen assessments of FCO2, soil temperature, and soil moisture were carried out under the remaining straw from the combination of summer sequences and winter crops over a 51-day period. Subsequently, soil physical, chemical, and microbiological attributes were assessed at depths of 0–0.10 and 0.10–0.20 m. The experiment was conducted in strips in a randomized block design with three replications. The multivariate analysis showed that the characterization of the pattern of FCO2 and other soil attributes as a function of the management with summer and winter crop residues differed according to the soil layer. In the 0.10–0.20 m layer, no difference was observed between treatments. However, the contents of clay, organic matter, sum of bases, microbial biomass carbon, dehydrogenase and amylase enzyme activity, and humification index of organic matter in the most superficial soil layer (up to 0.10 m) contributed to characterize differences in FCO2. Therefore, FCO2 variation is more influenced by soil microorganisms and the management in the most superficial layer. Soil attributes such as organic matter, enzyme activity, and biomass carbon had a higher influence on FCO2 dynamics in the 0–0.10 m layer, while soil density became a significant factor in FCO2 variation in the subsurface layer (0.10–0.20 m). Strategies such as soil management under no-tillage systems can be considered very efficient because, regardless of the residues generated by different crops, it contributes significantly to reduce FCO2, assisting in mitigating greenhouse gases in agriculture. Further studies on soil metagenomic analyses with quantification of functional genes related to carbon cycle will allow establishing direct relationships between FCO2 and microbiota dynamics and soil management since microbiota is the most sensitive bioindicator to changes in the environment.
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13328. 题目: Phytoremediation of multi-metal contaminated mine tailings with Solanum nigrum L. and biochar/attapulgite amendments
文章编号: N19052514
期刊: Ecotoxicology and Environmental Safety
作者: Xinxin Li, Xu Zhang, Xinlei Wang, Zhaojie Cui
更新时间: 2019-05-25
摘要: A greenhouse experiment was conducted to investigate an enhanced phytoremediation technique for multi-metal contaminated mine tailings by Solanum nigrum L. and using biochar/attapulgite as soil amendments. The 10% attapulgite (MA2) and 10% biochar (MB2) were recommended as the optimum chemical proportions for amendment materials. Plant length and fresh weight in the MA2/MB2-applied treatments were significantly higher than that in the non-amended treatment, indicating MA2 and MB2 amendments could alleviate metal phytotoxicity. Metal uptake in plant leaves was lower with MA2 and MB2 application than that in the non-amended treatment. However, metal uptake in plant roots was significantly increased with MA2 and MB2 application from the fifth month, suggesting that MA2 and MB2 had significant enhancement on metal stabilization. Temporal variation of metal translocation in soil-to-plant system showed that the function of MA2 and MB2 reached the plateau nearly in the seventh month. The removal rates of metals were higher after the application of MA2 than MB2, and by the following order: Cu (39.6%) > Zn (35.0%) > Cd (34.1%) > Hg (32.1%) > Pb (31.8%) > Mn (19.1%). The synergistic effect between S. nigrum L. and MA2/MB2 appeared to be particularly effective in terms of metal phytostabilization, and MA2 was superior to MB2.

13329. 题目: Effect of land use and carbonates on organic matter stabilization and microbial communities in Mediterranean soils
文章编号: N19052513
期刊: Geoderma
作者: Mireia Martí-Roura, Frank Hagedorn, Pere Rovira, Joan Romanyà
更新时间: 2019-05-25
摘要: Soil organic matter (SOM) is sensitive to land use and to physico-chemical soil properties as well soil microbial communities controlling SOM stabilization. Our study aimed at exploring how carbonates of Mediterranean soils – known to stabilize SOM by enhancing soil aggregation and binding SOM by calcium – are affecting SOM and microbial communities under different land uses. In soils with and without carbonates sampled in forests, cultivated and abandoned fields, we have fractionated SOM-pools according to particle sizes and determined C mineralization rates and polyvalent cations in these fractions. In agreement with larger scale assessments in the Mediterranean, our results show that SOM contents are greater in forest than in agricultural soils, but that the differences among land use types depend on carbonate contents. While SOM contents are greater in carbonated soils of forests, cultivated soils have low SOM levels independent of the carbonate content, presumably due to a reduced protection of particulate SOM by century-long intense tillage. Forest soils contain particularly large amounts of SOM associated with the coarser soil fraction. In this fraction, C mineralization was smallest in the carbonated forest soil, possibly due to a low SOM quality indicated by high C/N ratios and low δ15N values. Greater contents of Ca, Fe and Al in carbonated soils also suggests that stabilization through Ca and phyllosilicates was important. Mineralization of sand-associated SOM was highest in cultivated and abandoned soils, which is indicative for a small SOM stabilization, which in turn might restrict SOM accumulation after land abandonment. Microbial communities assessed by phospho-lipid fatty acid signatures and microbial carbon use efficiency were more closely associated with land use than with carbonate content – a pattern that reflects the distribution of C pools among size fractions which differed more strongly among land use types than between soils with and without carbonates.

13330. 题目: Photodegradation of 2-(2-hydroxy-5-methylphenyl)benzotriazole (UV-P) in coastal seawaters: Important role of DOM
文章编号: N19052512
期刊: Journal of Environmental Sciences
作者: Xi Chen, Jieqiong Wang, Jingwen Chen, Chengzhi Zhou, Feifei Cui, Guoxin Sun
更新时间: 2019-05-25
摘要: Benzotriazole UV stabilizers (BT-UVs) have attracted concerns due to their ubiquitous occurrence in the aquatic environment, and their bioaccumulative and toxic properties. However, little is known about their aquatic environmental degradation behavior. In this study, photodegradation of a representative of BT-UVs, 2-(2-hydroxy-5-methylphenyl)benzotriazole (UV-P), was investigated under simulated sunlight irradiation. Results show that UV-P photodegrades slower under neutral conditions (neutral form) than under acidic or alkaline conditions (cationic and anionic forms). Indirect photodegradation is a dominant elimination pathway of UV-P in coastal seawaters. Dissolved organic matter (DOM) from seawaters accelerate the photodegradation rates mainly through excited triplet DOM (3DOM), and the roles of singlet oxygen and hydroxyl radical are negligible in the matrixes. DOM from seawaters impacted by mariculture exhibits higher steady-state concentration of 3DOM ([3DOM]) relative to those from pristine seawaters, leading to higher photosensitizing effects on the photodegradation. Halide ions inhibit the DOM-sensitized photodegradation of UV-P by decreasing [3DOM]. Photodegradation half-lives of UV-P are estimated to range from 24.38 to 49.66 hr in field water bodies of the Yellow River estuary. These results are of importance for assessing environmental fate and risk UV-P in coastal water bodies.
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13331. 题目: Soil microbial response to metal contamination in a vegetated and urban brownfield
文章编号: N19052511
期刊: Journal of Environmental Management
作者: Jay Prakash Singh, Bhagyashree P. Vaidya, Nina M. Goodey, Jennifer Adams Krumins
更新时间: 2019-05-25
摘要: The ubiquity of urban brownfields presents not only a challenge for environmental managers but also an opportunity to study the functional aspects of degraded ecosystems that are in close contact with human habitation. In this study, we investigate the soil microbial community response to heavy metal contamination at Liberty State Park (LSP), an urban brownfield in Jersey City, NJ, USA. Heavy metal contamination of the soils at LSP is heterogeneous, varying widely across site and among metals. We collected soils along a previously mapped gradient of metal contamination at LSP and sampled soil from a local and uncontaminated reference site (Hutcheson Memorial Forest (HMF)) for comparison. For all soils, we measured soil heavy metal concentrations, soil organic carbon content, bacterial density, and extracellular phosphatase activity as a proxy of ecosystem functioning. Additionally, we analyzed the microbial community composition using high-throughput sequencing. Data show that some sites within LSP have significantly higher phosphatase activity compared to HMF, indicating that some heavily contaminated LSP soils are highly functional. We also found that soil organic carbon and bacterial density have a significant and positive relationship with phosphatase activity. The microbial community analyses showed that the bacterial communities were sensitive to heavy metals and that the composition was significantly affected in particular by copper, zinc, and lead. The fungal communities, however, did not vary significantly with heavy metals. Our results shed important light on the composition and functioning of urban brownfield soils. A deeper understanding of these unique ecosystems is required for successful remediation, restoration and urban sustainability.

13332. 题目: Evaluating storage and pool size of soil organic carbon in degraded soils: Tillage effects when crop residue is returned
文章编号: N19052510
期刊: Soil and Tillage Research
作者: Yan Zhang, Xiujun Li, Edward G. Gregorich, Neil B. McLaughlin, Xiaoping Zhang, Yafei Guo, Yan Gao, Aizhen Liang
更新时间: 2019-05-25
摘要: Conventional tillage in Northeast China involves complete removal of crop residue and deep plowing, both of which cause significant loss of soil organic carbon (SOC). Our study aimed to evaluate SOC storage and pool sizes in degraded soils when post-harvest residue is returned to degraded soil and different tillage systems are used. We measured SOC under no-tillage (NT), ridge-tillage (RT) and moldboard plow (MP) and compared storage across treatments. We used sulfuric acid hydrolysis to separate and evaluate the size of two labile pools and one recalcitrant pool. There was no difference in crop yields (and hence C inputs) across tillage treatments over 12 years. SOC storage in the plow layer (0–20 cm) increased in all tillage systems compared to soils in the degraded state but the rate of increase was greater under NT and RT than MP. There was increased variability when we assessed deep SOC storage (0–30 cm) and SOC storage at this depth was the same across tillage systems, but still higher than in the initially degraded state. Changes observed in the size of labile and recalcitrant pools indicated these occurred mainly in the surface 0–5 cm and that RT induced slight changes in the chemical composition of SOC. Our results indicate that returning residues to degraded soils: 1) replenished SOC levels but the rate of replenishment was highest under conservation tillage, 2) had no effect on yields (C inputs) and deep SOC storage across tillage treatments, and 3) induced subtle differences in SOC pool size.

13333. 题目: Anaerobically-digested sludge conditioning by activated peroxymonosulfate: Significance of EDTA chelated-Fe2+
文章编号: N19052509
期刊: Water Research
作者: Jiaqi Wang, Min Yang, Ruiping Liu, Chengzhi Hu, Huijuan Liu, Jiuhui Qu
更新时间: 2019-05-25
摘要: This study investigates the efficiency of anaerobically-digested sludge (ADS) conditioning using peroxymonosulfate (PMS) activated by EDTA chelated-Fe2+ process (PMS-EDTA-Fe2+), and the roles and mechanism of EDTA are explored by investigating the capillary suction time (CST), specific resistance to filtration (SRF), bound water content (BWC), extracellular polymeric substances (EPS), iron species transformation, sludge morphology, and active radicals formation. PMS-EDTA-Fe2+ process exhibits better performance in sludge dewatering than PMS-Fe2+ process. Upon the introduction of EDTA at optimum molar ratio of EDTA to Fe2+ REDTAFe2 of 1 : 3, CST, SRF, and BWC are decreased by 60.0%, 70.6%, and 1.5%, and the cell viability is decreased from 75.4% to as low as 24.7%. EDTA introduction significantly enhances the yield of active radicals (i.e., SO4 and OH) by nearly 50% as compared to PMS-Fe2+ process. This effect contributes to stronger cells lysis as indicated by SEM and CLSM, and the contents of polysaccharide and protein in total EPS fractions are increased by 19.2% and 37.4% accordingly. Additionally, EDTA increases the iron mobility by forming FeII/III-EDTA complexes and potentially inhibits ADS coagulation at high doses. The total dissolved iron (FeTot_dis) concentration increases from 203.4 mg/L to 601.4 mg/L due to the introduction of EDTA at 0.4 mmol/g VSS, and the dominant iron species in supernatant transformed from Fe2+ to Fe3+ accordingly. The optimization of EDTA doses is significant to balance oxidation and coagulation effects and to achieve better dewatering performance.
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13334. 题目: Halide-specific enhancement of photodegradation for sulfadiazine in estuarine waters: Roles of halogen radicals and main water constituents
文章编号: N19052508
期刊: Water Research
作者: Qun Zhao, Qi Fang, Huaying Liu, Yingjie Li, Huishu Cui, Biaojun Zhang, Senlin Tian
更新时间: 2019-05-25
摘要: Although photochemical transformation is a major degradation pathway for antibiotics in surface freshwaters, the photodegradation of antibiotics from freshwaters downstream into seawater is largely unknown. Herein, sulfadiazine was adopted as a representative antibiotic to probe the alteration of photolytic kinetics along freshwater to seawater sampled from Qinzhou Bay, China. The results showed that the photodegradation rate constants of sulfadiazine significantly increased in estuarine waters along freshwaters to seawaters. Experiments in synthetic water samples with isolated local dissolved organic matter (IL-DOM) indicated that the increased photodegradation of sulfadiazine is attributed to the integrative effect of both IL-DOM and halide ions. Radical quenching experiments with tert-butanol (quenching of ·OH) and isopropanol (quenching of both ·OH and reactive halogen species, RHS) demonstrated that RHS are largely responsible for the halide-specific enhancement in the photodegradation of sulfadiazine, rather than other reactive species, such as triplet-excited IL-DOM and ·OH. However, triplet-excited IL-DOM was involved in the production of RHS by the oxidation of halide ions by the triplet-excited states. Experiments conducted with DOM analogues verified DOM-sensitized RHS formation, and the degradation induced by RHS is positively correlated with the triplet-excited reduction potentials of DOM analogues. These findings are helpful in deeply understanding the transformation of antibiotics, and demonstrate the importance of RHS-induced degradation in antibiotics fate models in estuarine water systems.
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13335. 题目: Formation of mixed Eu(III)-CO3-fulvic acid complex: Spectroscopic evidence and NICA-Donnan modeling
文章编号: N19052507
期刊: Chemical Geology
作者: Yasmine Z. Kouhail, Marc F. Benedetti, Pascal E. Reiller
更新时间: 2019-05-25
摘要: Humic substances impact the fate of radionuclides in the environment. The formation of mixed complexes between lanthanides(III), carbonates, and humic substances is still a matter of debate and further studies are needed. Time-resolved luminescence spectroscopy (TRLS) is used to evidence the presence of Eu(III)-CO3-SRFA ternary complexes in media representative of environmental conditions. The evolutions of the Eu(III) luminescence spectra from the 5D07F0 to the 5D07F2 transitions are showing modifications of the asymmetry ratio — area ratio of the 5D07F2 over the 5D07F1 transition — that indicates the presence of several species in addition to the EuCO3+ and Eu-SRFA complexes. The occurrence of bi-exponential decay times, with one decay time faster than one from Eu3+, is typical of the occurrence of fulvic complex, even in the presence of carbonate. The analyses of the indirect excitation of the Eu-CO3-SRFA system are used to build complexation isotherms varying either SRFA or total carbonate concentrations in the framework of the NICA-Donnan modeling of the Eu(III)-SRFA system. In view of the restricted pH range, no strict attribution to the different possible types of sites can be done. Different complex(es) formations are considered and discussed.
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13336. 题目: Targeted removal of organic foulants in landfill leachate in forward osmosis system integrated with biochar/activated carbon treatment
文章编号: N19052506
期刊: Water Research
作者: Bilal Aftab, Yong Sik Ok, Jinwoo Cho, Jin Hur
更新时间: 2019-05-25
摘要: Forward osmosis (FO) has been adopted to treat complex wastewater such as landfill leachate due to its high rejection of organics. In this study, the in-line adsorptive process using biochar (BC) or powdered activated carbon (PAC) was applied to a cross flow FO system to enhance the mitigation of the FO membrane fouling from landfill leachate. The changes in the leachate composition along the treatments were tracked by excitation emission matrix-parallel factor analysis (EEM-PARAFAC) to identify tryptophan-like (C1), fulvic-like (C2), and humic-like (C3) components. After a single operation of FO, the C1 was found to be the main constituent responsible for membrane fouling irrespective of varying operation conditions regarding draw solute concentrations and flow rates. Both sorbents (i.e., BC and PAC) exhibited the preferential removal behavior towards C1 > C2 > C3, which was well supported by their individual adsorption isotherm model parameters. The addition of in-line adsorption treatment to FO resulted in substantial improvements in the filtered volume (>57%) and the flux recovery (>80%) compared to the single FO operation. Without chemical cleaning of membrane, the flux was fully recovered at a dose of 10 g/L BC or 0.3 g/L of PAC. A significant and negative correlation was found between the flux recovery and the C1 of the feed leachate or the corresponding spectral peak intensity (p < 0.05) for the integrated FO system, suggesting the potential of using on-line fluorescence monitoring for the performance of the integrated system in terms of fouling mitigation. This study provided a new insight into the effectiveness of BC or PAC adsorption as the in-line integration with an FO system for the targeted removal of FO membrane foulants in landfill leachate.
图文摘要:

13337. 题目: Enhanced aerobic sludge granulation by applying carbon fibers as nucleating skeletons
文章编号: N19052505
期刊: Chemical Engineering Journal
作者: Jie Xu, Heliang Pang, Junguo He, Mengfei Wang, Jun Nan, Lin Li
更新时间: 2019-05-25
摘要: A novel granulation technique by adding carbon fibers (CFs) as the skeletons of aerobic granular sludge (AGS) was developed in this study. Three sequential batch reactors (SBRs) named R1, R2 and R3 were operated over 5 months under low hydraulic shear force (HSF). Comparatively, the R2 and R3 had short CFs and long CFs added to the sludge mixture, respectively. The results indicated that adding CFs accelerated the maturation of granules and improved the stability of AGS, while the AGS in R1 disintegrated twice due to the overgrowth of filamentous bacteria, and appeared in a mixture of flocs and AGS eventually. Total amount of protein and polysaccharide in extracellular polymeric substances (EPS) showed little difference among three reactors, whereas their contents in tightly bound EPS of AGS in R2 and R3 were much higher than that in loose bound EPS during granulation. Confocal laser scanning microscopy (CLSM) images showed that the β-d-glucopyranose polysaccharides of AGS in R2 and R3 were more concentrated in the outer layer, but uniformly distributed in the AGS in R1, indicating that CFs might maintain the structural stability of AGS by providing skeletons together with β-d-glucopyranose polysaccharides. High throughput sequencing analysis showed that the relative abundance of functional bacteria, especially Candidatus_Accumulibacter, was extremely increased due to the addition of CFs. This study indicated that adding CFs is an effective method for aerobic sludge granulation under low HSF.
图文摘要:

13338. 题目: Linking phytoplankton primary production and chromophoric dissolved organic matter in the sea
文章编号: N19052504
期刊: Progress in Oceanography
作者: Carles Guallar, Jordi Flos
更新时间: 2019-05-25
摘要: The link between phytoplankton primary production (PPP) and chromophoric dissolved organic matter (CDOM) has been demonstrated indirectly in the laboratory, but not directly in the sea. Here, for the first time, we report a strong link between PPP and CDOM in a study carried out in coastal marine waters around Barcelona (NW Mediterranean) in contrasting seasons. We measured relevant correlations between a254 CDOM concentration and both PPP (r = 0.89, p < 0.001, n = 16; r = 0.76, p < 0.01, n = 10; and r = 0.68, p < 0.001, n = 26; for summer, winter–spring and both seasons together, respectively) and the specific production rate at optimal light intensity (PmB; r = 0.77, p < 0.001, n = 16; r = 0.86, p < 0.01, n = 10; and r = 0.85, p < 0.001, n = 26; for the same seasons). Based on our findings, we design a model that predicts PPP very well, using a254 CDOM, water temperature and photosynthetically active radiation (PAR) (R2 = 0.84, p < 0.001, n = 26).Relationships between CDOM concentration parameters (measured at wavelengths of 280, 300, 340, 355, 375, 412 and 460 nm) and variables associated to CDOM processes (chlorophyll-a, bacterial abundance, turbidity related to sediment resuspension and PAR) were also evaluated. Bacterial abundance is significantly correlated with CDOM concentration measured at higher wavelengths when all samples are considered (e.g., r = 0.82, p < 0.001, n = 26, for a355 CDOM). However, in seasonal data analysis, the correlations decrease slightly (summer season: e.g., r = 0.79, p < 0.001, n = 16, for a355 CDOM) or become non-significant (winter–spring season: e.g., r = -0.02, p = 0.95, n = 10, for a355 CDOM). Sunlight photobleaching and sediment resuspension processes significantly influence CDOM dynamics in the summer (for a300 CDOM: r = -0.72, p < 0.001, n = 16; and r = 0.67, p < 0.01, n = 16, respectively).

13339. 题目: Impacts of long-term plant residue management on soil organic matter quality, Pseudomonas community structure and disease suppressiveness
文章编号: N19052503
期刊: Soil Biology and Biochemistry
作者: Bryony E.A. Dignam, Maureen O'Callaghan, Leo M. Condron, Jos M. Raaijmakers, George A. Kowalchuk, Steven A. Wakelin
更新时间: 2019-05-25
摘要: The microbiome of grassland soils provides ecosystem services essential to plant health and productivity, including nutrient cycling and suppression of soil-borne diseases. Understanding how soil management practices affect soil microbial communities will provide opportunities by which indigenous soil microbes and their functions can be managed to sustain or promote plant growth and enhance disease suppressiveness. Here, we investigated the impact of 20 years of plant residue management in a long-term grassland field trial on soil chemical and (micro)biological properties, in particular the suppression of damping-off disease of kale caused by the fungal root pathogen Rhizoctonia solani AG 2–1. Plant residue management led to significant variation in the community structure of the bacterial genus Pseudomonas between treatments. Soil organic matter quality (inferred carbon recalcitrance) was responsible for 80% of the observed variation in Pseudomonas community structure. Furthermore, increased Pseudomonas species diversity (Shannon's index), microbial activity, soil organic matter content, and carbon availability distinguished suppressive (low disease) soils from conducive (high disease) soils. More specifically, Pseudomonas species diversity and richness (Margalef's) were identified as the primary parameters explaining the greatest proportion (>30%) of variation in the disease suppressive capacity of soils across treatments. Collectively, our results suggest that management-induced shifts in Pseudomonas community composition, notably species diversity and richness, provide a better indicator of disease conduciveness for a broad-host range fungal pathogen than soil chemical parameters. In conclusion, our study indicates that frequent addition of organic residues to agricultural grassland soils enhances the diversity and activity of plant-beneficial bacterial taxa.

13340. 题目: Environmental effects on soil microbial nitrogen use efficiency are controlled by allocation of organic nitrogen to microbial growth and regulate soil gross N mineralization
文章编号: N19052502
期刊: Soil Biology and Biochemistry
作者: Shasha Zhang, Qing Zheng, Lisa Noll, Yuntao Hu, Wolfgang Wanek
更新时间: 2019-05-25
摘要: Microbial nitrogen use efficiency (NUE) is the efficiency by which microbes allocate organic N acquired to biomass formation relative to the N in excess of microbial demand released through N mineralization. Microbial NUE thus is critical to estimate the capacity of soil microbes to retain N in soils and thereby affects inorganic N availability to plants and ecosystem N losses. However, how soil temperature and soil moisture/O2 affect microbial NUE to date is not clear. Therefore, two independent incubation experiments were conducted with soils from three land uses (cropland, grassland and forest) on two bedrocks (silicate and limestone). Soils were exposed to 5, 15 and 25 °C overnight at 60% water holding capacity (WHC) or acclimated to 30 and 60% WHC at 21% O2 and to 90% WHC at 1% O2 over one week at 20 °C. Microbial NUE was measured as microbial growth over microbial organic N uptake (the sum of growth N demand and gross N mineralization). Microbial NUE responded positively to temperature increases with Q10 values ranging from 1.30 ± 0.11 to 2.48 ± 0.67. This was due to exponentially increasing microbial growth rates with incubation temperature while gross N mineralization rates were relatively insensitive to temperature increases (Q10 values 0.66 ± 0.30 to 1.63 ± 0.15). Under oxic conditions (21% O2), microbial NUE as well as gross N mineralization were not stimulated by the increase in soil moisture from 30 to 60% WHC. Under suboxic conditions (90% WHC and 1% O2), microbial NUE markedly declined as microbial growth rates were strongly negatively affected due to increasing microbial energy limitation. In contrast, gross N mineralization rates increased strongly as organic N uptake became in excess of microbial growth N demand. Therefore, in the moisture/O2 experiment microbial NUE was mainly regulated by the shift in O2 status (to suboxic conditions) and less affected by increasing water availability per se. These temperature and moisture/O2 effects on microbial organic N metabolism were consistent across the soils differing in bedrock and land use. Overall it has been demonstrated that microbial NUE was controlled by microbial growth, and that NUE controlled gross N mineralization as an overflow metabolism when energy (C) became limiting or N in excess in soils. This study thereby greatly contributes to the understanding of short-term environmental responses of microbial community N metabolism and the regulation of microbial organic-inorganic N transformations in soils.

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