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23961. 题目: Rare earth elements in soil profiles of various ecosystems across Germany
文章编号: N19020313
期刊: Applied Geochemistry
作者: Julia Mihajlovic, Albrecht Bauriegel, Hans-Joachim Stärk, Niko Roßkopf, Jutta Zeitz, Gerhard Milbert, Jörg Rinklebe
更新时间: 2019-02-03
摘要: Rare earth elements (REEs) are of emerging interest. In the environment, they occur in minerals, however, they are also used in many key technologies and in agriculture. In consequence, REEs are released into the environment and have thus an impact on it. However, our knowledge regarding REEs in soils is incomplete. We selected eight soil profiles across Germany aiming to determine REE contents (aqua regia) and potential mobilization (hydroxylammonium chloride and hot water extractable) and to explore relations between REEs and soil properties. The composition of the parent material strongly influenced by the ice ages during the Pleistocene (especially in northeastern Germany) is a crucial factor differentiating the content of REEs in our studied soils. The silty, clayey soils in the western part of Germany possessed higher REE contents than the sandy and peaty soils in the northeast (average REE content Cambisols: 825 μmol kg⁻¹, Retisols: 407 μmol kg⁻¹, Arenosol 180 μmol kg⁻¹, Histosols 122 μmol kg⁻¹) because REE can adsorb onto clay minerals. The characteristic soil genetic processes of each soil type were reflected by the vertical distribution of the REE content. The vertical distribution of REEs and the hydroxylammonium chloride-extractable REE contents were mainly controlled by Al, Fe, Mn and their oxides (additional to clay) which provide important sorption sites for REEs. High contents of clay, Al/Fe/and Mn oxides caused high REE contents. The hydroxylammonium chloride-extractable REE contents varied in average from 266 to 8 μmol kg⁻¹ in the soils. The hot water extractable REE contents (in average 0.94 μmol kg⁻¹) tended to be higher in horizons which were rich in organic matter. In future, mechanistic experiments concerning the dynamics of REE mobilization should be performed as well as monitoring in plants and wildlife to improve our knowledge about REEs in the environment.
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23962. 题目: Photoconversion of U(VI) by TiO₂: An efficient strategy for seawater uranium extraction
文章编号: N19020312
期刊: Chemical Engineering Journal
作者: Ping Li, Jingjing Wang, Yun Wang, Jianjun Liang, Bihong He, Duoqiang Pan, Qiaohui Fan, Xiangke Wang
更新时间: 2019-02-03
摘要: Uranium extraction from seawater is of significant importance for the sustainable utilization of uranium in the near future; however, several challenges remain owing to the low uranium concentration and high salinity of seawater. In this work, for the first time, photocatalysis by TiO₂ was introduced for U(VI) extraction from seawater. The photocatalysis method achieved a high uranium extraction capacity of 3,960 mg/g without saturation. To evaluate the performance of the photocatalysis in the potential real applications, the influence of environmental factors was systematically studied. The results showed that H⁺ in solution competed with U(VI) ions for the photogenerated e^-, inhibiting U(VI) photoreduction. Inversely, U(VI) photoreduction was facilitated at pH > 6.0 and was adequate for U(VI) extraction from seawater. The efficiency of U(VI) photoreduction can also be inhibited by the high initial U(VI) concentration, high salinity, and high TiO₂ dose. Methanol can accelerate U(VI) photoreduction by consuming photogenerated holes. Similarly, humic acid can promote U(VI) photoreduction at acidic conditions, and the reaction efficiency was slightly hindered over pH ∼6.5. Although the photoactivity was inhibited to some extent under specific conditions, it was proven that U(VI) could be completely extracted in all systems by increasing the irradiation time. X-ray photoelectron spectroscopy, X-ray diffraction and X-ray absorption near edge structure confirmed that U(VI) was transformed into U(IV) during photocatalysis and that UO₂ was mainly formed on the TiO₂ surface. The extraction of uranium in real seawater is also feasible and the deposited uranium could be easily recovered using a Na₂CO₃ solution after standing in air for several hours. Therefore, photocatalysis is demonstrated to be an eco-friendly, facile, economical and sustainable approach for uranium extraction from seawater.
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23963. 题目: Graphene based ZnO nanoparticles to depolymerize lignin-rich residues via UV/iodide process
文章编号: N19020311
期刊: Environment International
作者: Mahmoud Mazarji, Merlin Alvarado-Morales, Panagiotis Tsapekos, Gholamreza Nabi-Bidhendi, Niyaz Mohammad Mahmoodi, Irini Angelidaki
更新时间: 2019-02-03
摘要: In this work, potassium iodide (KI) and graphene oxide (GO) were utilized to promote the selectivity of photocatalytic process for alkali lignin oxidation over ZnO. Different concertation of GO was added during the microwave synthesis procedure of ZnO, and the characterization results revealed that graphene can shift the conduction band to more reducing potential, resulting to higher production of superoxide anion radicals (O₂⁻) compared to OH. Response Surface Methodology revealed the most suitable interaction among loading of GO, KI and irradiation time on lignin and total phenolic compound (TPC) degradation. Specifically, the optimal conditions (i.e. maximum lignin (52%) and minimum TPC (55%) degradation) were at [KI] = 0.64 mM; GO content into ZnO 1.2 mg/mL; 240 min of irradiation time. The results showed that higher addition of graphene into structure of ZnO could preserve more phenolics from degradation due to less production of OH. Furthermore, the addition of KI at optimized conditions could enhance the selectivity of degradation of lignin and phenolics via producing I radicals and quenching the excess amount of generated OH, respectively. The lower generation of OH at optimized conditions was quantitatively confirmed by a photoluminescence simplified technique. In addition, the effect of the photocatalytic process on substrate's anaerobic degradability was examined in order to evaluate the suitability of the pretreated solution for energy recovery. Indeed, besides the higher TPC concentration, the biogas production of treated straw at optimized conditions was increased by 35% compared to the untreated sample.
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23964. 题目: Organic carbon: An overlooked factor that determines the antibiotic resistome in drinking water sand filter biofilm
文章编号: N19020310
期刊: Environment International
作者: Kun Wan, Menglu Zhang, Chengsong Ye, Wenfang Lin, Lizheng Guo, Sheng Chen, Xin Yu
更新时间: 2019-02-03
摘要: Biofilter, an essential water treatment process, is reported to be the harbor of bacterial antibiotic resistance genes (ARGs). Due to the oligotrophic characteristic of source water, filter biofilm is largely influenced by the concentration of organic carbon. The objective of this study was to investigate the effect of organic carbon concentration on shaping bacterial antibiotic resistome in filter biofilm. Our study was based on pilot-scale sand filters, and we investigated the antibiotic resistome using high-throughput qPCR. A total of 180 resistance genes from eight categories of antibiotics were detected in 15 biofilm samples of three sand filters. The results indicated that higher concentration of influent organic carbon led to lower diversity of bacterial community and richness of antibiotic resistance genes (ARGs) in biofilm. We discovered a negative correlation (p ≤ 0.01) between the richness of ARGs and the corresponding TOC level. Moreover, the absolute abundance of ARGs was positively correlated (p ≤ 0.05) with the abundance of 16S rRNA gene and was determined by the organic carbon concentration. Sand filters with gradient influent organic carbon concentration led to the formation of different antibiotic resistomes and canonical correspondence analysis (CCA) indicated that difference in bacterial community composition was likely the main reason behind this difference. We also observed a similar trend in the relative abundance of ARGs, which increased with the depth of sand filters. However, this trend was more pronounced in filters with low organic carbon concentrations. Overall, this study revealed that the organic carbon concentration determined the absolute abundance of ARGs and also shaped the diversity and relative abundance of ARGs in drinking water sand filters. These results may provide new insights into the mechanism of persistent bacterial antibiotic resistance in drinking water treatment.
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23965. 题目: Effects of extracellular polymeric substances of Pseudomonas fluorescens, citrate, and oxalate on Pb sorption by an acidic Ultisol
文章编号: N19020309
期刊: Ecotoxicology and Environmental Safety
作者: Jackson Nkoh Nkoh, Hai-lung Lu, Xiao-ying Pan, Ge Dong, Muhammad Aqeel Kamran, Ren-Kou Xu
更新时间: 2019-02-03
摘要: The continuous production of low molecular weight (LMW) organic acids by plants and microorganisms coupled with the continuous presence of extracellular polymeric substances (EPS) in soils is a guarantee that the mobility of heavy metals in soils will be controlled. The effects of citrate, oxalate, and EPS on the adsorption of Pb by an acidic Ultisol were studied both as a function of pH and ionic strength. Electrokinetic potential measurements were also employed to observe to what extent each ligand affected the surface charge property of the Ultisol. All the ligands shifted the zeta potential of the Ultisol to the negative direction, implying that the surface charge of the soil became more negative. The effect on the zeta potential of the soil was observed in the order of oxalate ˃ citrate ˃ EPS. The quantity of Pb adsorbed at each pH (3.0–7.0) reflected the corresponding change in the zeta potential as induced by each ligand. The presence of the ligands shifted the isoelectric point of the Ultisol from 4.8 to 3.2 for the EPS system and below 3.0 for the citrate and oxalate systems. More Pb was adsorbed in the presence of oxalate than in the presence of citrate and EPS. The two most outstanding mechanisms that governed the adsorption of Pb by the Ultisol were (1) electrostatic attraction which was supported by the increase in negative zeta potential of the Ultisol and, (2) complexation which was supported by the lesser proportion of Pb adsorbed in the citrate system at higher pH and also by the spectroscopic data for EPS. The combination EPS + citrate + oxalate was more effective in enhancing the adsorption of Pb than the combination EPS + oxalate and EPS + citrate.
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23966. 题目: Silver nanoparticles: An integrated view of green synthesis methods, transformation in the environment, and toxicity
文章编号: N19020308
期刊: Ecotoxicology and Environmental Safety
作者: Tiago Alves Jorge de Souza, Lilian Rodrigues Rosa Souza, Leonardo Pereira Franchi
更新时间: 2019-02-03
摘要: Nowadays, silver nanoparticles (AgNPs) are the most widely used nanoparticles (NPs) in the industry due to their peculiar biocidal features. However, the use of these NPs still runs into limitations mainly because of the low efficiency of environmental friendly synthesis methods and lack of size standardization. When NPs are release in the environment, they can be transformed by oxidation, adsorption or aggregation. These modification shows a dual role in toxic response of AgNPs. The adsorption of natural organic matter from environment on AgNPs, for example, can decrease their toxicity. Otherwise oxidation occurred in the environment is also able to increase the release of toxic Ag⁺ from NPs. Thus, the current review proposes an integrated approach of AgNP synthetic methods using bacteria, fungi, and plants, AgNP cytotoxic and genotoxic effects as well as their potential therapeutic applications are also presented.
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23967. 题目: Factors influencing DBPs occurrence in tap water of Jinhua Region in Zhejiang Province, China
文章编号: N19020307
期刊: Ecotoxicology and Environmental Safety
作者: Xiaoling Zhou, Lili Zheng, Shiyan Chen, Hongwei Du, Benimana Muhire Gakoko Raphael, Qianyun Song, Fuyong Wu, Jianrong Chen, Hongjun Lin, Huachang Hong
更新时间: 2019-02-03
摘要: Investigating the occurrence of disinfection by-products (DBPs) and identify the related influencing factors in drinking water is essentially important to control DBPs risk. In this study, 64 tap water samples were collected from 8 counties (or county level cities) in Jinhua Region of Zhejiang Province, China. Results showed that the median (range) of trihalomethane (THMs), haloacetic acids (HAAs), haloacetonitriles (HANs), haloketones (HKs) and halonitromethanes (HNMs) were 23.2 (9.1–40.9), 15.3 (5.8–38.6), 2.2 (0.7–7.6), 2.1 (0.2–6.4) and 0.7 (0.2–2.9) µg/L, respectively. HAAs, HANs, HKs and HNMs levels were generally higher in summer than in winter or spring, while for THMs in most counties, higher levels occurred in winter than in summer or spring. Spatially, Yongkang, Yiwu and Dongyang had higher DBPs levels than Pujiang, Pan’an, Lanxi, Wuyi and Jinhua, which was generally consistent with their economy development (GDP). Correlation analysis showed that DBPs occurrence in tap water was significantly related with physicochemical parameters. Principle component analysis further suggested that organic matter (DOC and UVA₂₅₄) are the major factors influencing the occurrence of THMs, HAAs, HANs and HKs in tap water, while for HNMs, both the organic (DOC and UVA₂₅₄) and inorganic factors (e.g. Temp, NO₂^--N, pH, Br^- and NH₄⁺-N) played important role in its formation.
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23968. 题目: Multi-colony coral skeletal Ba/Ca from Singapore’s turbid urban reefs: relationship with contemporaneous in-situ seawater parameters
文章编号: N19020306
期刊: Geochimica et Cosmochimica Acta
作者: J.T.I. Tanzil, N.F. Goodkin, T.M. Sin, M.L. Chen, G.N. Fabbro, E.A. Boyle, A.C. Lee, K.B. Toh
更新时间: 2019-02-03
摘要: The ratio of barium to calcium in coral skeletons (Ba/Ca_coral) is broadly used as a proxy for tracking terrestrial/river runoff. There are, however, inconsistencies in Ba/Ca_coral records that have prompted caution in its reliability as an environmental proxy. Direct comparisons between in-situ seawater measurements and coral Ba/Ca are therefore needed to ensure accurate proxy calibration and interpretation. The current study represents the first to test Ba/Ca_coral against years-long monthly-resolution contemporaneous measurements of several in-situ seawater parameters i.e. dissolved seawater barium (Ba_SW), temperature, salinity, suspended sediments, sedimentation rate and photosynthetically active radiation. We analysed the Ba/Ca_coral of six Porites lutea corals sampled from two turbid reefs in Singapore, and explored relationships with in-situ seawater parameters over the period 2008–2015. Our study found poor agreement in Ba/Ca_coral from replicate corals sampled from the same reef, and only one of the six colonies analysed showed significant but weak Ba/Ca_coral–Ba_SW and Ba/Ca_coral–Ba/Ca_SW relationships. There was also no clear relationship between Ba/Ca_coral and skeletal luminescence G/B (a coral proxy strongly linked with salinity and river runoff). This implies that 1) the incorporation of terrestrially derived humic-like substances into the coral is independent of Ba, and 2) it is likely factors other than freshwater discharge/flood events are driving the poor reproducibility of Ba/Ca_coral and disconnect with Ba_SW at our study sites. We found a positive relationship between Ba/Ca_coral and organic suspended solids for 4 of the 6 colonies analysed that suggests biological mechanisms such as feeding could be driving skeletal Ba incorporation. A negative relationship between Ba/Ca_coral and total sedimentation rate was also found, suggesting that within reef sediment fluxes may be influencing spatio-temporal variability of the Ba-supply. Ba incorporation into coral skeleton, especially in dynamic, turbid settings such as those found in Singapore, is likely more complex than previously thought. Our results highlight the possibility of high heterogeneity in coral responses to environmental conditions, and the need for careful selection of colonies and a site-specific, replicated approach when attempting to apply Ba/Ca_coral as a trace element proxy.

23969. 题目: Effects of metal cations on coupled birnessite structural transformation and natural organic matter adsorption and oxidation
文章编号: N19020305
期刊: Geochimica et Cosmochimica Acta
作者: Qian Wang, Peng Yang, Mengqiang Zhu
更新时间: 2019-02-03
摘要: Birnessite, a layered manganese (Mn) oxide, possesses extraordinary metal adsorption and oxidation activity, and thus imposes impacts on many biogeochemical processes. The reactivity of birnessite strongly relies on its Mn oxidation state composition (the proportions of Mn II, III and IV), particularly by the Mn(III) proportion. Partial reduction of birnessite transforms birnessite to be Mn(II, III)-rich or to MnOOH and Mn₃O₄, and thus strongly affects birnessite reactivity. As a metal scavenger, naturally occurring birnessite contains abundant transition and alkali and alkaline earth metal cations in its structure; however, the effects of these metal cations on the partial reduction-induced transformation of birnessite remain unknown. We examined the effects of Zn²⁺, Mg²⁺, Ca²⁺ and ionic strength (controlled by NaCl) on transformation of birnessite (δ-MnO₂) during partial reduction by fulvic acid (FA) at pH 8 and FA/MnO₂ mass ratios (R) of 0.1 or 1 over 600 hours under anoxic conditions. Results showed that low ionic strength (0 versus 50 mM NaCl) disfavored FA adsorption, fractionation and oxidation, and thus disfavored formation of Mn(III) in the reacted birnessite. Compared to the 50 mM NaCl system, all divalent cations (Mg²⁺, Ca²⁺ and Zn²⁺) favored FA adsorption and fractionation. Both Mg²⁺ and Ca²⁺ significantly enhanced FA oxidation at the early stage but barely at the late stage, whereas Zn²⁺ strongly suppressed FA oxidation during the entire experimental period. Due to adsorption competition, the presence of the divalent cations resulted in low concentration of Mn(II) adsorbed on vacancies of birnessite. Both Ca²⁺ and Mg²⁺ favored Mn(III) production in MnO₆ layers and on vacancies, with more Mn(III) produced in the layers, while Zn²⁺ inhibited Mn(III) production at both locations. A small portion of birnessite also transformed to feitknechtite and hausmannite, and the transformation seemed faster in the presence of the divalent cations than in NaCl solution. The formation of Mn(III) in the reacted birnessite can be ascribed to comproportionation between Mn(IV) and Mn(II) adsorbed on either vacancies or edge sites of birnessite. The low–valence Mn oxide phases likely formed via the comproportionation on the edges. The divalent cations affected Mn(III) concentrations of birnessite and formation of the low-valence Mn oxides by competing with Mn(II) for adsorption on edge/vacancy sites or stabilizing Mn(III) in the layers. This work indicates that divalent metal cations strongly influence reactivity and transformation of birnessite in the coupled Mn and C redox cycles, and that birnessite containing divalent cations can be an important adsorbent for natural organic carbon in Mn-rich environments. Overall, this study provides insights into the coupled cycles of Mn, trace metals and organic carbon in alkaline and saline environments.

23970. 题目: Middle–Upper Ordovician (Darriwilian–Sandbian) paired carbon and sulfur isotope stratigraphy from the Appalachian Basin, USA: Implications for dynamic redox conditions spanning the peak of the Great Ordovician Biodiversification Event
文章编号: N19020304
期刊: Palaeogeography, Palaeoclimatology, Palaeoecology
作者: Nevin P. Kozik, Seth A. Young, Chelsie N. Bowman, Matthew R. Saltzman
更新时间: 2019-02-03
摘要: The Evans Ferry section from the Appalachian Basin of eastern North America has been analyzed for chemostratigraphic trends to elucidate possible causal mechanisms facilitating the Great Ordovician Biodiversification Event (GOBE). Paired stable isotope (δ¹³C and δ³⁴S) analyses were used in this carbonate-dominated locality from the Appalachian Basin to reconstruct the marine redox states during this key period of rapid biodiversification. This succession is one of the most expanded Sandbian Stage (Upper Ordovician) deposits known from North America, and it allows new high-resolution reconstructions of long-term, global carbon and sulfur cycle fluctuations. The integrated geochemical and sequence-stratigraphic investigation presented here from the Laurentian epeiric seaway allows for possible identification of the contraction and expansion of reducing water masses during the Middle–Late Ordovician that may have been linked to global-marine paleoredox dynamics. Utilizing new conodont-based ⁸⁷Sr/⁸⁶Sr isotope stratigraphy along with previous conodont biostratigraphy, we can confidently correlate our stable isotope profiles to other carbonate successions globally. Carbonate facies indicate that this area experienced partial restriction from open-marine conditions during certain intervals in the Sandbian. These semi-restricted environments record carbon (δ¹³C_carb) isotope trends that are secular in nature, as they can be correlated to other successions across Laurentia and Baltica. We identify several intervals when δ¹³C_carb and δ³⁴S_CAS (carbonate-associated sulfate) trends are decoupled. These inverse stratigraphic trends are, at times, followed by parallel positive shifts in δ¹³C_carb and δ³⁴S_CAS. Causal mechanisms for the observed decoupled δ¹³C and δ³⁴S trends may include a wide variety of factors such as more closed-system, local biogeochemical processes associated in part with diagenesis, or they could instead reflect variations in the global fluxes of organic matter and pyrite burial linked to changing marine paleoredox conditions. The positive covariation in trends presented here likely represents transient increases in organic carbon and pyrite burial in response to expansion of reducing marine environments.

23971. 题目: A blessing in disguise? Natural organic matter reduces the UV light-induced toxicity of nanoparticulate titanium dioxide
文章编号: N19020303
期刊: Science of The Total Environment
作者: Simon Lüderwald, Vera Dackermann, Frank Seitz, Elena Adams, Alexander Feckler, Carsten Schilde, Ralf Schulz, Mirco Bundschuh
更新时间: 2019-02-03
摘要: Besides their economic value, engineered inorganic nanoparticles (EINPs) may pose a risk for the integrity of ecosystems. Among EINPs, titanium dioxide (nTiO₂) is frequently used and released into surface waters in the μg range. There, nTiO₂ interacts with environmental factors, influencing its potential to cause adverse effects on aquatic life. Although factors like ultra violet (UV) light and natural organic matter (NOM) are considered as ubiquitous, their joint impact on nTiO₂-induced toxicity is poorly understood. This study addressed the acute toxicity of nTiO₂ (P25; 0.00–64.00 mg/L; ~60 nm) at ambient UV light (0.00–5.20 W UVA/m²) and NOM levels (seaweed extract; 0.00–4.00 mg TOC/L), using the immobility of Daphnia magna as response variable. Confirming previous studies, effects caused by nTiO₂ were elevated with increasing UV radiation (up to ~280 fold) and mitigated by higher NOM levels (up to ~12 fold), possibly due to reduced reactive oxygen species (ROS; measured as ^•OH radicals) formation at lower UV intensities. However, contradicting to former studies, nTiO₂-mediated ROS formation was not proportional to increasing NOM levels: lower concentrations (0.04–0.40 mg TOC/L) slightly diminished, whereas a higher concentration (4.00 mg TOC/L) promoted the ROS quantity, irrespective of UV intensity. Measured ROS levels do not fully explain the observed nTiO₂-induced toxicity, whereas increasing acetylcholinesterase and glutathione-S-transferase activities in daphnids (in presence of 8.00 mg/L nTiO₂ and elevated UV intensity) point towards neurotoxic and oxidative stress as a driver for the observed effects. Hence, despite higher ^•OH levels in the treatments where 4.00 mg TOC/L were present, NOM was still capable of reducing nTiO₂-induced stress and ultimately adverse effects in aquatic life.
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23972. 题目: Evaluation of Pilot-Scale Biochar-Amended Woodchip Bioreactors to Remove Nitrate, Metals, and Trace Organic Contaminants from Urban Stormwater Runoff
文章编号: N19020302
期刊: Water Research
作者: Negin Ashoori, Marc Teixido, Stephanie Spahr, Gregory H. LeFevre, David L. Sedlak, Richard G. Luthy
更新时间: 2019-02-03
摘要: Stormwater is increasingly being valued as a freshwater resource in arid regions and can provide opportunities for beneficial reuse via aquifer recharge if adequate pollutant removal can be achieved. We envision a multi-unit operation approach to capture, treat, and recharge (CTR) stormwater using low energy, cost-effective technologies appropriate for larger magnitude, less frequent events. Herein, we tested nutrient, metal, and trace organic contaminant removal of a pilot-scale CTR system in the laboratory using biochar-amended woodchip bioreactors following eight months of aging under field conditions with exposure to real stormwater. Replicate columns with woodchips and biochar (33% by weight), woodchips and straw, or woodchips only were operated with continuous, saturated flow for eight months using water from a watershed that drained an urban area consisting of residential housing and parks in Sonoma, California. After aging, columns were challenged for five months by continuous exposure to synthetic stormwater amended with 50 μg L^–1 of six trace organic contaminants (i.e., fipronil, diuron, 1H-benzotriazole, atrazine, 2,4-D, and TCEP) and five metals (Cd, Cu, Ni, Pb, Zn) frequently detected in stormwater in order to replicate the treatment unit operation of a CTR system. Throughout the eight-month aging and five-month challenge experiment, nitrate concentrations were below the detection limit after treatment (i.e., <0.05 mg N L^-1). The removal efficiencies for metals in all treatments were >80% for Ni, Cu, Cd, and Pb. For Zn, about 50% removal occurred in the woodchip-biochar systems while the other systems achieved about 20% removal. No breakthrough of the trace organic compounds was observed in any biochar-containing columns. Woodchip columns without biochar removed approximately 99% of influent atrazine and 90% of influent fipronil, but exhibited relatively rapid breakthrough of TCEP, 2,4-D, 1H-benzotriazole, and diuron. The addition of straw to the woodchip columns provided no significant benefit compared to woodchips alone. Due to the lack of breakthrough of trace organics in the biochar-woodchip columns, we estimated column breakthrough with a diffusion-limited sorption model. Results of the model indicate breakthrough for the trace organics would occur between 10,000 and 32,000 pore volumes. Under ideal conditions, this could be equivalent to decades of service assuming failure by other processes (e.g., clogging, biofouling) does not occur. These results indicate that multiple contaminants can be removed in woodchip-biochar reactors employed in stormwater treatment systems with suitable flow control and that the removal of trace organic contaminants is enhanced significantly by addition of biochar.
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23973. 题目: Effect of Dissolved Oxygen on Efficiency of TOC Reduction by UV at 185 nm in an Ultrapure Water Production System
文章编号: N19020301
期刊: Water Research
作者: Jeongyun Choi, Jinwook Chung
更新时间: 2019-02-03
摘要: The effect of dissolved oxygen (DO) on the degradation of methanol by ultraviolet (UV) light at 185 nm (UV-185) was examined in this study. The experiments were conducted using a bench-scale experimental apparatus that was operated under continuous conditions. In the control tests with various DO conditions, it was confirmed that UV irradiation of water without methanol produced approximately 54 μg/L of H₂O₂ and removed 15% to 90% of the DO. The production of H₂O₂ was affected by the mixing conditions within the UV reactor and the dose of UV. The degradation efficiency of methanol by UV-185 irradiation improved linearly with increasing DO concentration, with more than 90% DO consumption. The maximum total organic carbon (TOC) removal rate was observed at 100 μg/L DO and 433 mW·sec/cm², the highest DO and dosage conditions in this study. The production of H₂O₂ was also affected by DO concentration in the feed water, especially at the high UV dosage, in which lower H₂O₂ production was observed at higher DO.
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23974. 题目: Mutual relationships of biochar and soil pH, CEC, and exchangeable base cations in a model laboratory experiment
文章编号: N19020210
期刊: Journal of Soils and Sediments
作者: Niguss Solomon Hailegnaw, Filip Mercl, Kateřina Pračke, Jiřina Száková, Pavel Tlustoš
更新时间: 2019-02-02
摘要: Purpose: The majority of biochar studies use soils with only a narrow range of properties making generalizations about the effects of biochar on soils difficult. In this study, we aimed to identify soil properties that determine the performance of biochar produced at high temperature (700 °C) on soil pH, cation exchange capacity (CEC), and exchangeable base cation (Ca²⁺, K⁺, and Mg²⁺) content across a wide range of soil physicochemical properties. Materials and methods: Ten distinct soils with varying physicochemical properties were incubated for 12 weeks with four rates of biochar application (0.5, 2, 4, and 8% w/w). Soil pH, CEC, and exchangeable base cations (Ca²⁺, K⁺, and Mg²⁺) were determined on the 7th and 84th day of incubation. Results and discussion: Our results indicate that the highest biochar application rate (8%) was more effective at altering soil properties than lower biochar rates. Application of 8% biochar increased pH significantly in all incubated soils, with the increment ranging up to 1.17 pH unit. Biochar induced both an increment and a decline in soil CEC ranging up to 35.4 and 7.9%, respectively, at a biochar application rate of 8%. Similarly, biochar induced increments in exchangeable Ca²⁺ up to 38.6% and declines up to 11.4%, at an 8% biochar application rate. The increment in CEC and exchangeable Ca²⁺ content was found in soils with lower starting exchangeable Ca²⁺ contents than the biochar added, while decreases were observed in soils with higher exchangeable Ca²⁺ contents than the biochar. The original pH, CEC, exchangeable Ca²⁺, and texture of the soils represented the most crucial factors for determining the amount of change in soil pH, CEC, and exchangeable Ca²⁺ content. Conclusions: Our findings clearly demonstrate that application of a uniform biochar to a range of soils under equivalent environmental conditions induced two contradicting effects on soil properties including soil CEC and exchangeable Ca²⁺ content. Therefore, knowledge of both biochar and soil properties will substantially improve prediction of biochar application efficiency to improve soil properties. Among important soil properties, soil exchangeable Ca²⁺ content is the primary factor controlling the direction of biochar-induced change in soil CEC and exchangeable Ca²⁺ content. Generally, biochar can induce changes in soil pH, CEC, and exchangeable Ca²⁺, K⁺, and Mg²⁺ with the effectiveness and magnitude of change closely related to the soil’s original properties.

23975. 题目: A novel TiO₂/biochar composite catalysts for photocatalytic degradation of methyl orange
文章编号: N19020209
期刊: Chemosphere
作者: Lili Lu, Rui Shan, Yueyue Shi, Shuxiao Wang, Haoran Yuan
更新时间: 2019-02-02
摘要: A series of TiO₂/biochar composite catalysts were prepared by the hydrolysis method for the degradation of methyl orange, where biochar was obtained from the pyrolysis of waste walnut shells. The catalysts were examined by scanning electron microscope (SEM), energy dispersive spectrometer (EDS), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), photoluminescence spectroscopy (PL) and X-ray photoelectron spectroscopy (XPS), elemental analysis and ultra violet-visible diffuse reflectance spectroscopy (UV–vis DRS). The photocatalytic activity results showed that the catalysts noted as CT0.1/1, CT0.2/2 and CT 0.5/1 exhibited higher catalytic activity than that of pure TiO₂. Besides, catalyst CT0.2/1 exhibited the highest catalytic activity (the decolorization efficiency of 96.88% and the mineralization efficiency of 83.23% were obtained), attributed to the synergistic effect of biochar and TiO₂, while CT1/1 possessed the lowest activity due to the shelter of light by the excess biochar. After 5 repeated use, the catalyst CT0.2/1 still exhibited rather high activity toward the degradation of MO, where the decolorization efficiency and mineralization efficiency of MO achieved 92.45% and 76.56%, and the loss of activity was negligible.

23976. 题目: Comparison of the accumulation and metabolite of fluoxetine in zebrafish larva under different environmental conditions with or without carbon nanotubes
文章编号: N19020208
期刊: Ecotoxicology and Environmental Safety
作者: Zhenhua Yan, Guanghua Lu, Hongwei Sun, Xuhui Bao, Runren Jiang, Jianchao Liu, Yong Ji
更新时间: 2019-02-02
摘要: Few studies have focused on the influence of environmental conditions on the bioavailability of pollutants interacted with nanomaterials in organisms. In this study, we primarily compared the influence of multiwalled carbon nanotubes (MWCNTs) on the bioavailability of fluoxetine in zebrafish (Danio rerio) larva under different environmental conditions: natural organic matter (NOM) and salinity. The results showed that fluoxetine accumulated in the larvae and then transformed into the metabolite norfluoxetine, with the metabolic rates from 2.8 to 3.5. Following co-exposure to MWCNTs, the accumulation of fluoxetine and norfluoxetine were further enhanced, suggesting a superior carrier of MWCNTs for fluoxetine, especially the functional MWCNTs. The consistent increase in the fluoxetine and norfluoxetine accumulation highlights the bioavailability of absorbed fluoxetine on MWCNTs in zebrafish larvae. The presence of NOM promoted the accumulation of fluoxetine and norfluoxetine in zebrafish, but alleviated the carrier effects of MWCNTs, acting as a natural antidote. Salinity negatively influenced the bioavailability of fluoxetine in the larvae, and further reversed the enhancements caused by MWCNTs. These findings provide a new insight into the influence of environmental conditions on the interactions between nanomaterials and pollutants in organisms.
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23977. 题目: Mercury speciation in various aquatic systems using passive sampling technique of diffusive gradients in thin-film
文章编号: N19020207
期刊: Science of The Total Environment
作者: Arne Bratkič, Katja Klun, Yue Gao
更新时间: 2019-02-02
摘要: Mercury (Hg) is one of the primary health concerns in natural and urbanised environments due to past and present natural and anthropogenic emissions. Its environmental cycle is driven by redox reactions, microbial metabolism and organic matter (OM) interactions, which may all lead to formation of bioaccumulative organic Hg species; methylmercury (MeHg), with damaging consequences for human and ecosystem health. Hence, Hg lability and bioavailability has been the focus of many investigations and assessed with a variety of chemical proxies in order to improve understanding of the conditions that lead to enhanced bioavailability of Hg and its species. We investigated Hg labile species with Diffusive Gradient in Thin-film technique (DGT) in the water column and sediment of Zenne River (Brussels, Belgium) and Gulf of Trieste (North Adriatic). They represent two contemporary important Hg-impacted areas; the former by anthropogenic urban pollution, and the latter by historic pollution from Hg mining. Hg speciation of labile inorganic and methylmercury in these two environments was not yet investigated using DGT technique. The results show labile Hg species changing with season in the water column of Zenne River, while the sediments are the source of bioavailable MeHg to the water column that is transported further creating a halo effect in the region. Values of labile Hg species for water column and sediments in Gulf of Trieste differ from previous research, highlighting the need for more investigation into Hg bioavailability. MeHg/THg ratios were compared to other sampling methods for labile Hg species.
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23978. 题目: High-resolution prediction of organic matter concentration with hyperspectral imaging on a sediment core
文章编号: N19020206
期刊: Science of The Total Environment
作者: Kévin Jacq, Yves Perrette, Bernard Fanget, Pierre Sabatier, Didier Coquin, Ruth Martinez-Lamas, Maxime Debret, Fabien Arnaud
更新时间: 2019-02-02
摘要: In the case of environmental samples, the use of a chemometrics-based prediction model is highly challenging because of the difficulty in experimentally creating a well-ranged reference sample set. In this study, we present a methodology using short wave infrared hyperspectral imaging to create a partial least squares regression model on a cored sediment sample. It was applied to a sediment core of the well-known Lake Bourget (Western Alps, France) to develop and validate a model for downcore high resolution LOI550 measurements used as a proxy of the organic matter. In lake and marine sediment, the organic matter content is widely used, for example, to reconstruct carbon flux variations through time. Organic matter analysis through routine analysis methods is time- and material-consuming, as well as not spatially resolved. A new instrument based on hyperspectral imaging allows high spatial and spectral resolutions to be acquired all along a sediment core. In this study, we obtain a model characterized by a 0.95 r prediction, with 0.77 wt% of model uncertainty based on 27 relevant wavelengths. The concentration map shows the variation inside each laminae and flood deposit. LOI550 reference values obtained with the loss on ignition are highly correlated to the inc/coh ratio used as a proxy of the organic matter in X-ray fluorescence with a correlation coefficient of 0.81. This ratio is also correlated with the averaged subsampled hyperspectral prediction with a r of 0.65.
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23979. 题目: Comparison of short-term dosing ferrous ion and nanoscale zero-valent iron for rapid recovery of anammox activity from dissolved oxygen inhibition
文章编号: N19020205
期刊: Water Research
作者: Yuan Yan, Yayi Wang, Weigang Wang, Shuai Zhou, Junjie Wang, Jianhua Guo
更新时间: 2019-02-02
摘要: As obligate anaerobes, anammox bacteria are sensitive to oxygen, which might hinder the maximization of anammox activity. However, there are very few effective strategies to rapidly recover anammox activity after its deterioration under exposure of oxygen. In this study, the activity recovery of anammox bacteria encountering dissolved oxygen (DO) exposure (0.2 and 2.0 mg L⁻¹) were compared by three strategies in short-term experiments, nZVI, Fe(II) dosing, and N₂ purging. nZVI is more effective in recovering anammox activity with a high DO exposure (2 mg L^‒1), compared to a low DO exposure (0.2 mg L^‒1). After inhibiting by 2.0 mg L⁻¹ DO, anammox activity recovery (normalized to the control) was ranked in the order of nZVI (5 mg L⁻¹) addition (63±8.2%)> Fe(II) (5 mg L⁻¹) addition (41±8.0%) >N₂ purging (39 ± 4.0%). In contrast to Fe(II) ion additions, the shell structure of nZVI combined with the buffering effect of biomass-extracellular polysaccharide (EPS) prevented the sharp pH variation and excessive dissolved Fe(II)/Fe(III) in solution. Under such circumstances, nZVI addition (5 and 25 mg L⁻¹) increased the intracellular reactive oxygen species (ROS) to a moderate level (<200%), which might be responsible for the better activity recovery of anammox than that of Fe(II) addition and N₂ purging. Specifically, 5 mg L⁻¹ nZVI dosage moderately enhanced the intracellular O₂⁻ production (∼150% of the control) after scavenging 2.0 mg L⁻¹ DO, and the anammox activity recovered better than that of both 5 and 25 mg L⁻¹ Fe(II) ions additions. However, high dosage nZVI (75 mg L⁻¹) inhibited anammox activity in spite of low or high DO exposure. Our findings elucidate that appropriate amount of nZVI (a short-term dosing) can rapidly recover anammox activity when anammox bacteria encountering oxygen exposure accidentally and could be useful in facilitating the robust operation of anammox-based processes.
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23980. 题目: Mycobacterial metabolic characteristics in a water meter biofilm revealed by metagenomics and metatranscriptomics
文章编号: N19020204
期刊: Water Research
作者: Junge Zhu, Ruyin Liu, Nan Cao, Jianwei Yu, Xinchun Liu, Zhisheng Yu
更新时间: 2019-02-02
摘要: Mycobacteria represent one of the most persistent bacterial populations in drinking water distribution system (DWDS) biofilm communities; however, mycobacterial in situ metabolic profiles are largely unknown. In this study, the metabolic characteristics of mycobacteria in a household water meter biofilm were unveiled using a coupled metagenomic/metatranscriptomic approach. The water meter biofilm appeared to express nitrogenase genes (nifDKH) and a full complement of genes coding for several carbon-fixation pathways, especially the Calvin cycle, suggesting the CO₂ sequestration and dinitrogen fixation potential of the biofilm. These findings indicate that it may be difficult to prevent the formation of DWDS biofilms simply by controlling the availability of organic carbon or nitrogen. The composite genome of mycobacteria (CG-M) was reconstructed based on the obtained omics data. CG-M shared similar genome phylogeny and virulence-factor profiles with Mycobacterium avium complex, suggesting that population CG-M might represent a member of mycobacteria with pathogenicity. According to the gene expression patterns, population CG-M showed the metabolic potential to assimilate CO₂ via the Calvin cycle and/or anaplerotic reactions, and even to grow autotrophically with CO as the sole carbon and energy source. This suggests that organic carbon may not be a limiting factor for mycobacterial growth in DWDSs. Moreover, our results suggest that mycobacterial aromatic degradation is primarily achieved through the catechol meta-cleavage pathway, and biofilm mycobacteria could prefer phosphate as the phosphorus source.
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