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25301. 题目: Microplastic Impacts on Microalgae Growth: Effects of Size and Humic Acid
文章编号: N20011512
期刊: Environmental Science & Technology
作者: Ge Liu, Ruifen Jiang, Jing You, Derek C. G. Muir, Eddy Y. Zeng
更新时间: 2020-01-15
摘要: Research has already demonstrated the toxic effects of microplastics (MPs) on different biota. However, the underlying toxic mechanism of MPs remains to be elucidated, especially the effect of particle size and the presence of dissolved organic matter in water. This study investigated the impact on Scenedesmus obliquus exposed in five types of polystyrene particle suspensions with different sizes and surface charges, in the presence and absence of humic acid (HA). Results indicated that the 50% growth inhibition rate of S. obliquus showed no significant difference between the five types of MPs, but the toxic mechanism varied with particle size. Larger size MPs caused adverse effects by blocking the light transport and affecting photosynthesis, while smaller ones destroyed the cell wall by adsorbing onto the algae surface. Also, the addition of HA significantly alleviated the toxicity of smaller size MPs, but not of the larger ones. Scanning electron microscopy images and the reactive oxygen species assay demonstrated that the HA could form a corona on the surface of MPs, reduce the affinity to microalgae, and minimize the adverse effect. Together, these findings identified important factors in determining the toxicity of MPs, providing valuable data for risk assessment of MPs.

25302. 题目: Enhancing methanogenesis from anaerobic digestion of propionate with addition of fe oxides supported on conductive carbon cloth
文章编号: N20011511
期刊: Bioresource Technology
作者: Yanguang Xu, Mingwei Wang, Qilin Yu, Yaobin Zhang
更新时间: 2020-01-15
摘要: In this study, a Fe₂O₃ supported on conductive carbon cloth (FC) was prepared and supplemented into anaerobic digestion reactors to improve propionate degradation. In the FC-supplemented reactors, the cumulative methane production and propionate degradation increased by 15.4% and 19.67% compared with those of the control, respectively. Less methane production with H₂/CO₂ as the sole substrate in the culture taken from the FC reactors suggested that interspecies hydrogen transfer in the FC reactors was weaker. These results suggested that direct interspecies electron transfer (DIET) was established in the FC reactors to improve the performance. Fe₂O₃ increased the secretion of electron shuttle components of extracellular polymeric substances to increase electron exchange capacity of biomass of the FC reactors, which further facilitated the DIET. Analysis on microbial communities confirmed that the abundance of microorganisms-related DIET in the FC reactors was higher than that in the control.
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25303. 题目: Biological performance and fouling mitigation in the biochar-amended anaerobic membrane bioreactor (AnMBR) treating pharmaceutical wastewater
文章编号: N20011510
期刊: Bioresource Technology
作者: Linlin Chen, Peijin Cheng, Lu Ye, Hui Chen, Xiangyang Xu, Liang Zhu
更新时间: 2020-01-15
摘要: Anaerobic membrane bioreactor (AnMBR) is an advanced technology in treating pharmaceutical wastewater, but the membrane fouling limits its development. In this study, the biochar with adsorption capacity of biopolymers was added in AnMBR to investigate its potential in treating pharmaceutical wastewater and alleviating membrane fouling. In the biochar-amended AnMBR, adsorbable organic halogen (AOX) was removed effectively, and more COD was biotransformed into CH₄. Membrane fouling mitigation was achieved in the third stage with a 56% decrease of average transmembrane pressure difference (TMP) rising rate. The predominant culprit, proteins of extracellular polymeric substance (EPS-proteins) in sludge mixture and cake layer, was reduced significantly. Particularly, the proportion of micromolecular (0.1-0.15 kDa) EPS-proteins in cake layer was 1.5-folds that of the control group. The important bio-foulant genus Arcobacter aggregating on the membrane had less and almost half the relative abundance (16.5%) than that of the control group (30.7%).
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25304. 题目: Below ground residues were more conducive to soil organic carbon accumulation than above ground ones
文章编号: N20011509
期刊: Applied Soil Ecology
作者: Yang Wang, Yingde Xu, Jiubo Pei, Ming Li, Te Shan, Weijun Zhang, Jingkuan Wang
更新时间: 2020-01-15
摘要: Long-term intensive cultivation generally affects even soil fertility by decreasing the soil organic carbon (SOC) content. The returning of maize residues to the soil is documented as an effective measure to increase SOC and improve soil productivity. However, limited information is available on the turnover and storage of organic carbon (C) caused by the addition of different maize residue types to soil with different soil fertility levels. For this purpose, a 540-day in-site field experiment was carried on soils with low and high fertility levels amended with three types of ¹³C-labeled maize residues (root, stem and leaf) in Northeast China. The abundances of ¹³C in the soil samples were measured on the 60th, 90th, 180th, and 540th days after incubation. The results showed that the residual rate of the residue-derived C was higher in the high-fertility (HF) soil than that in the low-fertility (LF) soil on the 60th day (an average of 56.6% vs. 52.37%, P < 0.05). At the end of the experiment, the content of the residue-derived C in the root-amended treatment (0.5 and 0.4 g kg⁻¹ in the HF and LF soils, respectively) was higher than that in the stem-amended (0.4 and 0.3 g kg⁻¹ in the HF and LF soils, respectively) and leaf-amended (0.4 and 0.3 g kg⁻¹ in the HF and LF soils, respectively) treatments. The residual rates of the root-, stem- and leaf-derived C were 20.1%, 15.6%, and 15.4% in the LF soil and 20.4%, 18.3%, and 18.2% in the HF soil, respectively. The results revealed that the HF soil had higher capacity to retain exogenous residue C, and the residue-derived C contribution from below ground residues (roots) to SOC should be more important than that from above ground parts (leaves + stems) in a long-term period.

25305. 题目: Dynamics of soil aggregation and organic carbon fractions over 23 years of no-till management
文章编号: N20011508
期刊: Soil and Tillage Research
作者: Cláudia dos Reis Ferreira, Eduardo Carvalho da Silva Neto, Marcos Gervasio Pereira, Jair do Nascimento Guedes, Jean Sérgio Rosset, Lúcia Helena Cunha dos Anjos
更新时间: 2020-01-15
摘要: Evaluation of aggregate formation in no-till farming systems and the effects on soil organic matter can provide relevant insights into soil carbon storage, nutrient cycling, and soil susceptibility to erosion. However, there is little information on the soil aggregate formation pathways in no-till systems. This study aimed to investigate the effect of no-tillage duration on soil aggregates and soil organic matter compared with undisturbed soil in the rainy and dry season. The following experimental sites were analyzed: NT₇ (no-till management for 7 years), NT₁₄ (no-till management for 14 years), NT₂₃ (no-till management for 23 years) and AF, a preserved fragment of Atlantic Forest (reference area). Aggregate formation pathway was analysed/described according to the morphological pattern using a stereo microscope (LEICA M125), in magnification ranges between 20x and 40 × . Physical fractionation of organic matter was carried out by granulometric size separation, and humic substances were separated into humic acid, fulvic acid, and humin fractions by differential solubility. No-till management affected the dynamics of soil aggregation and organic matter fractions. In the long term, no-till farming reduced biological aggregation (52.5 ± 4.5 % in AF to 19.2 ± 3.1 % in NT₂₃), and increased physicochemical aggregation (21,2 ± 2.1 % in AF to 47.2 ± 5.1 % in NT₂₃), may be because the traffic-induced compaction resulting from seeding. However, over the years, no-till farming increased soil particulate organic carbon (POC), mineral-associated organic matter (MAOM) and humin contents because of the constant input of crop residues to surface layers. Our results suggest that the morphological classification analysis of soil aggregates was sensitive to changes in land use over time, consisting as an indicator practical, affordable, repeatable, and easily understood and interpreted, which may be used to ascertain changes in physical soil conditions.

25306. 题目: Potential of siltstone and its composites with biochar and magnetite nanoparticles for the removal of cadmium from contaminated aqueous solutions: Batch and column scale studies
文章编号: N20011507
期刊: Environmental Pollution
作者: Muhammad Imran, Zia Ul Haq Khan, Jibran Iqbal, Noor Samad Shah, Saima Muzammil, Shafaqat Ali, Nawshad Muhammad, Arwa Aziz, Behzad Murtaza, Muhammad Asif Naeem, Muhammad Amjad, Muhammad Shahid, Ali Zakir, Muhammad Rizwan
更新时间: 2020-01-15
摘要: The present study is the first attempt to evaluate the pilot and batch scale adsorption potential of siltstone (SS) and its nanocomposites with biochar (EDB/SS), magnetite nanoparticles (MNPs/SS) and MNPs/EDB/SS for Cd removal from contaminated water. The SS, EDB/SS, MNPs/SS and MNPs/EDB/SS were characterized with FTIR, XRD, BET, SEM, TEM, TGA and point of zero charge (PZC). The effects of adsorbent dosage, contact time, initial Cd concentration, pH and presence of competing ions were evaluated on the Cd removal and its adsorption. The order for Cd removal was: MNPs/EDB/SS > MNPs/SS > EDB/SS > SS (95.86–99.72% > 93.10–98.5% > 89.66.98–98.40% > 74.90–90%). Column scale experiments yielded maximum retention (95%) of Cd even after 2 h of injection at 100 mg Cd/L. The exhausted SS, EDB/SS, MNPs/SS and MNPs/EDB/SS were reused without losing significant adsorption potential. Similarly, maximum Cd adsorption (117.38 mg/g) was obtained with MNPs/EDB/SS at dose 1.0 g/L. The results revealed that coexisting cations reduced the Cd removal due to competition with Cd ions. The experimental results were better explained with Freundlich isotherm model and pseudo 2nd order kinetic models. The results revealed that SS and its composites can be used efficiently for the removal of Cd from contaminated water.
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25307. 题目: Lateral mobilization of soil carbon induced by runoff along karstic slopes
文章编号: N20011506
期刊: Journal of Environmental Management
作者: Leticia Gaspar, Lionel Mabit, Ivan Lizaga, Ana Navas
更新时间: 2020-01-15
摘要: Soil erosion induced by runoff is a main hydrological pathway for lateral transport of carbon in terrestrial landscapes. More information about how water erosion influences the carbon gains and losses at different erosional and depositional landform positions is critical, especially in fragile agroecosystems with a variety of land uses and ephemeral hydrological and sedimentological pulses, typical of Mediterranean environments. The purpose of this study is to characterize the lateral mobilization of soil organic and inorganic carbon (SOC and SIC) along topographically driven transects over a period of four decades in a sub-humid karstic area in northern Spain. The ¹³⁷Cs inventories and the characterization of terrain attributes of the study area were used to identify whether erosional or depositional processes have been predominant in the 58 sampling sites. Average soil losses and gains varied between −4 and +4 mm ha⁻¹ yr⁻¹, and the carbon patterns obtained are discussed in the context of the dominant hydrological processes in the study area. Results indicate that SOC and SIC losses were related to an increase in water flow accumulation, while the highest SOC gains were recorded at concave positions. Soil erosion processes and the content of SOC and SIC in soils are the two main factors controlling carbon budgets. The topographical and geomorphological characteristics of the transects, the spatial distribution of land uses and the presence of landscape linear elements such as terraces or paths, affect runoff and determine the sediment connectivity and carbon dynamics along the slopes. The combined use of ¹³⁷Cs and the perceptual model provides reliable SDR estimates benefiting the appraisals of the redistribution of eroded carbon. The knowledge of processes involved in the lateral carbon movement induced by runoff along karstic hillslopes provides a better understanding of the role of soil erosion as carbon source or sinks in the global carbon cycle.
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25308. 题目: Elucidating the negative effect of denitrification on aromatic humic substance formation during sludge aerobic fermentation
文章编号: N20011505
期刊: Journal of Hazardous Materials
作者: Mingzi Shi, Xinyu Zhao, Longji Zhu, Junqiu Wu, Taha Ahmed Mohamed, Xu Zhang, Xiaomeng Chen, Yue Zhao, Zimin Wei
更新时间: 2020-01-15
摘要: Humic substance (HS), as an aromatic compound, is the core product of aerobic fermentation. Denitrification-dependent degradation of aromatic compounds have been repeatedly observed in environment. However, few studies have elucidated the relationship between denitrification and aromatic HS during sludge aerobic fermentation. This study was conducted to investigate the effect of enhanced denitrification on aromatic HS formation. On the 24th day of sludge aerobic fermentation, five tests (CK, Run1, Run2, Run3 and Run4) were executed, and nitrate concentrations were adjusted to 480 ± 20, 500 ± 20, 1000 ± 20, 1500 ± 20 and 2000 ± 20 mg/kg with potassium nitrate, respectively. Analytical results demonstrated that nitrate addition increased denitrifying genes abundance and enhanced denitrification, which further reduced aromatic HS formation (p < 0.05). Especially in Run3, the concentrations of HS and humic acid on the 52nd day dramatically decreased by 12.9 % and 34.2 % in comparison with those on the 31 st day. High-throughput sequencing revealed that enhanced denitrification effectively stimulated the metabolism of denitrifying microorganisms with aromatic-degrading capability. Co-occurring network analysis indicated that some keystone taxa of denitrification aromatic-degrading microorganisms involved in the conversion of nitrate to nitrite were the most crucial for enhancing denitrification and reducing aromatic HS formation.
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25309. 题目: A new sea surface temperature proxy based on bacterial 3-hydroxy fatty acids
文章编号: N20011504
期刊: Organic Geochemistry
作者: Yi Yang, Canfa Wang, James A. Bendle, Xiaoguo Yu, Chao Gao, Xiaoxia Lü, Xiaoyan Ruan, Ruicheng Wang, Shucheng Xie
更新时间: 2020-01-15
摘要: 3-Hydroxy fatty acids (3-OH-FAs), derived from Gram-negative bacterial outer membranes, have received recent attention for their potential as new terrestrial pH and temperature proxies for palaeoclimate studies. However, it is not known whether 3-OH-FAs based proxies can be developed and applied to the marine environment. Here we analyze 3-OH-FAs from a latitudinal transect of marine surface sediments from the North Pacific Ocean (12 °N to 61 °N with a mean annual sea surface temperature (SST) range of 28.1 °C to 1.3 °C). The results show that distributions of 3-OH-FAs in marine sediments yield overall higher abundances of anteiso 3-OH-FA homologues compared to soils. Furthermore, 16S rRNA gene sequencing of the marine sediments and soils shows the Gram-negative bacterial community is dominated by Proteobacteria (ca. 94%) at the phylum level. In contrast, in regional soils the Gram-negative bacterial community is more diverse with significant contributions from Proteobacteria (ca. 50%), Acidobacteria (ca. 24%), Verrucomicrobia (6%), Bacteroidetes (6%) and other phyla. These distinct genomic and molecular differences suggest distinctly different aggregate compositions of bacteria that produce 3-OH-FA in the marine realm vs soils. Moreover, we find that the ratio of anteiso to normal C₁₃ 3-OH-FA (RAN₁₃) measured in surface sediments is highly correlated with mean annual SST throughout the temperature transect (1.3–28.1 °C). When applied to a short sediment core from the East China Sea, the SST changes reconstructed by the RAN₁₃ proxy are comparable to instrumental SST data. These findings demonstrate that RAN₁₃ and potentially other, so far undiscovered, proxies based on 3-OH-FAs have potential for environmental and palaeoclimate applications in marine environments.

25310. 题目: Effects of extracellular polymeric substance fractions on polyacrylamide demand and dewatering performance of digested sludges
文章编号: N20011503
期刊: Separation and Purification Technology
作者: Vu Hien Phuong To, Tien Vinh Nguyen, Heriberto Bustamante, Saravanamuthu Vigneswaran
更新时间: 2020-01-15
摘要: High polymer demand in sludge conditioning is an intractable aspect of the water industry. This study investigated the effects of extracellular polymeric substances (EPS) fractions on polyacrylamide demand for conditioning and dewatering performance. Specifically, it examined aerobically and anaerobically digested sludges from seven full-scale wastewater treatment plants (WWTPs). Our study successfully quantified the contributions of soluble EPS to polyacrylamide demand during conditioning and explained the role of tightly bound EPS (TB-EPS) in determining the digested sludges’ dewatering performance. Results show that the concentrations of soluble EPS in the sludges varied between 92 – 1148 mg/L. Experimental results also demonstrated that between 25% - 80% of polyacrylamides used for conditioning were wasted in “parasitic” reactions with soluble EPS. The residual cationic polyacrylamide left in solution, after the parasitic reactions, was substantial and varied between 35 – 254 mg/L. Despite this outcome, the zeta potential values of dewatered sludge cakes remained negative, i.e. between -24 – -35 mV. These indicated that the residual soluble cationic polyacrylamides would not have been absorbed on the negatively charged sludge particles. This explained the relatively poor performance of the dewatering stage in the treatment plants studied. Furthermore the results suggested the TB-EPS attached to the sludge particles would be responsible for the poor dewatering. We postulated that the TB-EPS would gelify and immobilize the water surrounding the sludge particles. Our study suggested that new and more effective polymers for conditioning are needed to both: (i) reduce polymer demand; and (ii) improve the dewatering performance.

25311. 题目: Translocating subtropical forest soils to a warmer region alters microbial communities and increases the decomposition of mineral-associated organic carbon
文章编号: N20011502
期刊: Soil Biology and Biochemistry
作者: Xiong Fang, Guoyi Zhou, Chao Qu, Wenjuan Huang, Deqiang Zhang, Yuelin Li, Zhigang Yi, Juxiu Liu
更新时间: 2020-01-15
摘要: It is not clear how soil organic carbon (SOC) and its related microbial processes respond to climate warming in subtropical forest, which limits our ability to predict the response and feedback of such forests to future warming. Here, we translocated a forest microcosm from a high-elevation site to a low-elevation site (600 m–30 m a.s.l.) in a subtropical forest, to study the responses of SOC fractions, microbial communities and enzyme activities to increases in soil temperature (ca. 1.69 °C). Results showed that translocation to a warmer region significantly decreased the total SOC content by an average of 21.1% after three years of soil warming. Warming non-significantly decreased the particulate organic C (POC) and microbial C (MBC) content by 15.7% and 15.2%, respectively, and increased the light fraction organic C (LFOC) and dissolved organic C (DOC) content by 15.5% and 2.3%, respectively. By contrast, warming significantly decreased the <53 μm fraction organic C (N-POC, −15.3%) and heavy fraction organic C (HFOC, −14.8%) content. Warming significantly decreased the relative abundance of total bacteria (−2.7%), G⁺ bacteria (−6.1%), G⁻ bacteria (−6.6%) and actinomycetes (−10.8%), but increased the relative abundance of fungi (+22%). The oxidase and mass-specific oxidase activities were significantly increased by 32–70% in the warming soils. The decline in the N-POC was highly correlated to the increases in the relative abundance of fungi, the ratio of fungal to bacterial biomass (F:B), oxidase and mass-specific oxidase activities. Our results suggest that climate warming may increase the potential for fungal decomposition of mineral-associated organic C by increasing oxidase activities, leading to greater C losses in the subtropical forest than previously estimated.

25312. 题目: Nitrogen addition has contrasting effects on particulate and mineral-associated soil organic carbon in a subtropical forest
文章编号: N20011501
期刊: Soil Biology and Biochemistry
作者: Jungang Chen, Wen Xiao, Chengyang Zheng, Biao Zhu
更新时间: 2020-01-15
摘要: Increasing atmospheric nitrogen (N) deposition has substantially affected carbon (C) and nutrient cycling in forest ecosystems. However, the responses of different soil organic carbon (SOC) fractions with different turnover rates to N addition are highly divergent, and the underlying mechanisms remain elusive. In this study, we explored the responses of surface soil (0–10 cm) characteristics and microbial communities to six years of experimental N addition (0, 50, 100 and 150 kg N ha⁻¹ yr⁻¹) in a subtropical evergreen broadleaf forest in southern China. Our results showed that N addition led to significant soil acidification (pH from 5.3 to 4.9). Microbial biomass carbon and total microbial, bacterial and fungal abundance (phospholipid fatty acid, PLFA) were reduced by N addition, but extracellular enzymes involved in C, N and phosphorus (P) cycling were not responsive to N addition. Soil extractable Ca²⁺ concentration was depleted by N addition, while other extractable cations (Fe³⁺, Al³⁺, Mg²⁺, K⁺, Na⁺) were not affected. Moreover, N addition did not significantly change the C and N concentration of bulk soil. We further separated the bulk soil into particulate organic matter (>53 μm, POM) and mineral-associated organic matter (<53 μm, MAOM) fractions by wet sieving. Interestingly, C in the POM fraction was significantly increased by N addition, while C in the MAOM fraction was depleted by N addition. Correlation analysis and structural equation modeling results suggested that N addition may suppress microbial decomposition of plant inputs and thus lead to accumulation of C in the POM fraction, while it may reduce the mineral sorption of microbial necromass and products and thus cause depletion of C in the MAOM fraction. Taken together, our results highlighted the vulnerability of soil C in the stable MAOM fraction to N addition, and emphasized the role of soil metals (particularly extractable Ca²⁺) and pH in controlling soil C storage under N addition.

25313. 题目: Assessment of Interactions between Transition Metals and Atmospheric Organics: Ascorbic Acid Depletion and Hydroxyl Radical Formation in Organic-Metal Mixtures
文章编号: N20011409
期刊: Environmental Science & Technology
作者: Manfei Lin, Jian Zhen Yu
更新时间: 2020-01-14
摘要: Excessive oxidative stress has been recognized as an important cause of the adverse health effects associated with exposure to ambient particulate matter (PM). Transition metals (TMs) (e.g., iron (Fe) and copper (Cu)) are known catalysts in the formation of reactive oxygen species (ROS) in surrogate lung fluid containing antioxidants. Humic-like substances (HULIS), extracted from atmospheric aerosols, retain the compositional complexity of real-world samples. It contains mixtures of organics that chelate TMs and was used in this work to examine the roles of atmospheric organics in affecting ROS formation and antioxidant depletion by TMs. Two types of metal-binding organics known to be present in HULIS, oxygen-containing (i.e., carboxylic acids) and reduced-nitrogen-containing organics (i.e., imidazoles), were first investigated for their effects on the ascorbic acid depletion (denoted as OPAA) and hydroxyl radical formation (denoted as OP•OH) from both Fe(II) and Cu(II) in phosphate buffered saline (pH 7.40) containing ascorbic acid. Our results show that carboxylic acids enhance the OPAA and OP•OH by TMs while imidazoles suppress them. Similar experiments using three HULIS samples with distinctly different chemical compositions revealed complexity in metal-organics interactions. While ambient HULIS showed negligible impacts, two biomass burning source HULIS samples from rice straw and sugar cane leaf burning displayed unambiguous suppression or enhancement effects on OPAA and OP•OH by TMs. The effect was metal-specific and source HULIS-specific. The distinct behaviors of the three HULIS types can be explained by their different chemical compositions, for example, outstanding higher level of alkaloid compounds (e.g., imidazoles) in rice straw burning HULIS was consistent with the suppression effect exerted by this source of HULIS. In addition, we found OPAA and OP•OH are well-correlated while the proportion of OP•OH/OPAA by Cu is noticeably lower than that by Fe, indicating varying sensitivity of the metals to different OP end points. Our work highlights the importance and complexity of metal-organics interactions and the advantages of comeasurements of ROS generation and antioxidant depletion when assessing oxidative stress elicited by atmospheric PM.

25314. 题目: Molecular Characteristics of Dissolved Organic Nitrogen and Its Interaction with Microbial Communities in a Prechlorinated Raw Water Distribution System
文章编号: N20011408
期刊: Environmental Science & Technology
作者: Hang Xu, Chenshuo Lin, Zhen Shen, Li Gao, Tao Lin, Hui Tao, Wei Chen, Jian Luo, Chunhui Lu
更新时间: 2020-01-14
摘要: Dissolved organic nitrogen (DON) represents a unique challenge in prechlorinated raw water distribution systems (PRWDSs) because of its contribution to the formation of harmful nitrogen-disinfection byproducts, influence upon biogeochemical processes, and unclear molecular characteristics. Here, Fourier transform ion cyclotron resonance mass spectrometry in combination with high-throughput sequencing was applied to elucidate the molecular changes of DON and biofilm microbial communities in a PRWDS in Yixing, China. Our study revealed that dynamic characteristics of DON are significantly correlated with the biofilm. The accumulation of refractory lignin-like compounds and CnHmOpN1 contributes to the higher recalcitrance molecular characteristics of DON in the effluent associated with Alphaproteobacteria, Planctomycetes, and Bacteroidetes. Additionally, with the help of prechlorination, the biofilm may change the DON characteristics and lead to higher oxygenation, higher m/z, and lower saturation during transportation. Despite the promotion of CnHmOpN1 and CnHmOpN3 at the early stage, we suggest that appropriate concentration of chlorine can add to the front end of raw water distribution pipes. Prechlorination may control the nitrification process and stabilize the rapid growth of diversity and concentration of low molecular weight DON, especially the refractory CnHmOpN1 in the effluent, which may help to improve treatment efficiency of drinking water treatment plants.

25315. 题目: Light absorption properties of brown carbon (BrC) in autumn and winter in Beijing: Composition, formation and contribution of nitrated aromatic compounds
文章编号: N20011407
期刊: Atmospheric Environment
作者: Xingru Li, Yang Yang, Shuiqiao Liu, Qing Zhao, Gehui Wang, Yuesi Wang
更新时间: 2020-01-14
摘要: Nitro-aromatic compounds (NACs) are an important part of brown carbon because of their strong light absorbing properties in the visible and near ultraviolet regions. In this study, the concentration and formation mechanism of eight NACs, as well as their relative contribution to the light absorption of methanol-extracted BrC, were determined from fine particle samples collected in Beijing using ultra-high performance liquid chromatography coupled with high resolution mass spectrometry and ultraviolet–visible light spectrophotometry. The average concentrations of the eight NACs were 20.27 ± 12.40 ng m−3 and 74.17 ± 50.66 ng m−3 in autumn and winter, respectively. Among the detected NACs, 4-nitrophenol (4NP) and 4-nitrocatechol (4NC) were the most abundant compounds. The correlation analysis showed that the NACs other than 2,4-dinitrophenol (2,4-DNP) are strongly intercorrelated. Significant correlations among nitro catechols (NCs), nitro salicylic acids (NSAs) and NO2 support their proposed origin from secondary formation in the presence of •OH + NO2 (daytime process) or •NO3+NO2 (nighttime process). Significant correlations among nitrate, sulfate and NSAs were also found, indicating that the nitration of salicylic acid by nitric acid and sulfuric acid was another possible mechanism formation of NSAs. The methanol-extracts in winter had much higher light absorption than those in autumn, which is in agreement with the trend of NACs but contrary to the trends of PM2.5, water soluble ions, organic carbon and elemental carbon. The average absorption Ångström exponents (AAEs) during autumn and winter were 4.62 and 5.55, respectively, suggesting that secondary transformation were the main sources of BrC. The light absorption of NACs accounted for 1.17% and 3.18% of the total methanol-soluble BrC light absorption at λ = 365 nm in autumn and winter, respectively, while their masses only accounted for 0.16% and 0.44% of the OC, respectively, demonstrating that although NACs are not the major contributor to BrC, but they are strong BrC chromophores, and their influence on solar radiation should be included in future modeling work.

25316. 题目: Soil organic carbon depletion in global Mollisols regions and restoration by management practices: a review
文章编号: N20011406
期刊: Journal of Soils and Sediments
作者: Xiangru Xu, Jiubo Pei, Yingde Xu, Jingkuan Wang
更新时间: 2020-01-14
摘要: Purpose: Mollisols are the most fertile, high-yielding soils in the world. During the past several decades, Mollisols have lost about 50% of their antecedent organic carbon (C) pool due to soil erosion, degradation, and other unsuitable human activities. Therefore, restoring soil organic C (SOC) to Mollisols via reasonable management is crucial to sustainable development and is important for environmental stability. However, the existing literature on SOC and soil quality has focused on one soil type or on a given region where Mollisols occur, and the degree of SOC depletion and stabilization in Mollisols have not been comprehensively evaluated. Overall, we propose to develop an optimum scheme for managing Mollisols, and we outline specific issues concerning SOC restoration and prevention of SOC depletion. Materials and methods: In this review, we identify the uncertainties involved in analyses of SOC in Mollisols as related to management practices. According to the existing literature on SOC in Mollisols at the global scale, we analyzed the results of SOC depletion research to assess management practices and to estimate the C amount stabilized in Mollisols. Results and discussion: The review shows that the SOC stocks in Mollisols in North America under cropped systems had 51 ± 4 (equiv. mass) Mg ha⁻¹ in the top 30 cm soil layer. The SOC contents in Northeast China decreased from 52 to 24 g kg⁻¹ (46%) after 150 years of cultivation management. All of the Mollisols regions in the world are facing the challenge of SOC loss, and this trend could have a negative influence on global climate change. Hence, it is very important to take proper measures to maintain and enhance organic C contents in Mollisols. Conclusions: We concluded that reasonable management practices, including no-tillage, manure and compost fertilization, crop straw returning, and mulching cultivation, are the recommended technologies. The C restoration in Mollisols is a truly win-win strategy for ensuring the security of food and soil resources while effectively mitigating global climate change. Thus, more attention should be given to protective management and land use for its impacts on SOC dynamics and soil properties in Mollisols regions.

25317. 题目: Application of biochar in advanced oxidation processes: supportive, adsorptive, and catalytic role
文章编号: N20011405
期刊: Environmental Science and Pollution Research
作者: Faheem, Jiangkun Du, Sang Hoon Kim, Muhammad Azher Hassan, Sana Irshad, Jianguo Bao
更新时间: 2020-01-14
摘要: The advanced oxidation processes (AOPs), especially sulphate radical (SO₄^•−)–based AOPs (SR-AOPs), have been considered more effective, selective, and prominent technologies for the removal of highly toxic emerging contaminants (ECs) due to wide operational pH range and relatively higher oxidation potential (2.5–3.1 V). Recently, biochar (BC)-based composite materials have been introduced in AOPs due to the dual benefits of adsorption and catalytic degradation, but the scientific review of BC-based catalysts for the generation of reactive oxygen species (ROSs) through radical- and non-radical-oriented routes for EC removal was rarely reported. The chemical treatments, such as acid/base treatment, chemical oxidation, surfactant incorporation, and coating and impregnation of minerals, were applied to make BC suitable as supporting materials (SMs) for the loading of Fenton catalysts to boost up peroxymonosulphate/persulphate/H₂O₂ activation to get ROSs including ^•OH, SO₄^•−, ¹O₂, and O₂^•− for targeted pollutant degradation. In this review, all the possible merits of BC-based catalysts including supportive, adsorptive, and catalytic role are summarised along with the possible route for the development prospects of BC properties. The limitations of SR-AOPs especially on production of non-desired oxyanions, as well as disinfection intermediates and their potential solutions, have been identified. Lastly, the knowledge gap and future-oriented research needs are highlighted.

25318. 题目: Lithology controlled soil organic carbon stabilization in an alpine grassland of the Peruvian Andes
文章编号: N20011404
期刊: Environmental Earth Sciences
作者: Songyu Yang, Boris Jansen, Karsten Kalbitz, Fresia O. Chunga Castro, Rutger L. van Hall, Erik L. H. Cammeraat
更新时间: 2020-01-14
摘要: Alpine grasslands of the Neotropical Andes have high soil organic carbon (SOC) stocks and provide crucial ecosystem services. However, stability of the SOC in these grasslands is not well-studied. Having insights into SOC stability contributes to a better understanding of ecosystem vulnerability and maintaining of ecosystem services. The objectives were to get a first insight into organic matter (OM) stabilization in soils from different bedrocks of Andean alpine grasslands near Cajamarca, Peru (7° 11″ S, 78° 35″ W) and how this controls SOC stocks. Samples were collected from soils formed on limestone and acid igneous rocks. Stabilization mechanisms of OM were investigated using selective extraction methods separating active Fe, Al and Ca fractions and determined SOC stocks. In both soil types, the results showed important contributions of complexation with and/or adsorption on Fe and Al (oxides) to OM stabilization. Exclusively in the limestone soils, Ca induced OM stabilization by promoting the formation of Ca²⁺ bridges between OM and mineral surfaces. Furthermore, no evidence showed that OM stabilization was controlled by crystalline Fe oxides, clay contents, allophones, Al toxicity or aggregate stability. Limestone soils had significantly higher SOC stocks (405 ± 42 Mg ha⁻¹) compared to the acid igneous rock soils (226 ± 6 Mg ha⁻¹), which is likely explained by OM stabilization related to Ca²⁺ bridges in addition to the stabilization related to Fe and Al (oxides) in the limestone soils. Our results suggest a shift from OM stabilization dominated by Fe and Al (oxides) to that with the presence of Ca-related cation bridges, with increasing pH values driven by lithology.

25319. 题目: Long-term alkaline conditions inhibit the relative abundances of tetracycline resistance genes in saline 4-chlorophenol wastewater treatment
文章编号: N20011403
期刊: Bioresource Technology
作者: Yahe Li, Jianguo Zhao, Yu Li, Badan Jin, Ke Zhang, Hongzhong Zhang
更新时间: 2020-01-14
摘要: Considering the occurrence and spread of antibiotic resistance genes (ARGs) pose significant risks to public health, the effects of long-term exposure to alkaline conditions on the relative abundances of tetracycline resistance genes (TRGs) were studied in saline 4-chlorophenol (4-CP) wastewater treatment. Alkaline conditions were maintained by supplying the co-metabolic carbon source of sodium acetate. Results showed that except for the 4-CP, the removal of pollutants was significantly inhibited, and the relative abundances of the most TRGs were repressed. In addition, the removal of pollutants and the relative abundances of TRGs were moderately affected by the NaCl addition. The proteins in the extracellular polymeric substances (EPS) played key roles in reducing the relative abundances of TRGs, which were altered by the microbial diversity. In conclusion, for the pollutants removal and ARGs reduction in refractory industrial wastewater treatment, alkaline conditions should be maintained by selecting suitable co-metabolic carbon sources.

25320. 题目: Influence of COD/SO₄²⁻ ratio on vinasse treatment performance by two-stage anaerobic membrane bioreactor
文章编号: N20011402
期刊: Journal of Environmental Management
作者: Ana Flávia Rezende Silva, Natalie Cristine Magalhães, Paulo Vitor Martinelli Cunha, Miriam Cristina Santos Amaral, Konrad Koch
更新时间: 2020-01-14
摘要: Vinasse is sulfate-rich wastewater due to sulfuric acid dosage in some ethanol production steps. The vinasse sulfate concentration is subject to seasonal variations. A two-stage anaerobic membrane bioreactor (2S-AnMBR) was operated to evaluate the influence of COD/SO₄²⁻ ratio on vinasse treatment performance by using a real vinasse sample under natural seasonal COD/SO₄²⁻ variation. This ratio directly affects the sulfidogenesis efficiency, which is responsible for different forms of inhibition in the anaerobic treatment of sulfate-rich wastewater. The bioreactor presented a stable performance at the highest COD/SO₄²⁻ ratios (50–94), with high removal of chemical oxygen demand (COD) (97.5 ± 0.4%) and volatile fatty acids (VFA) (98.0 ± 0.6%), but low removal of sulfate (69.9 ± 9.5%), indicating lower sulfate reducing bacteria (SRB) activity. In the lowest COD/SO₄²⁻ ratios (9–20), a deterioration in the removal of organic matter (87.0 ± 1.3%) and VFA (69.8 ± 15.5%) was observed, accompanied by sulfate removal increase (92.9 ± 2.6%). A significant correlation between COD fractions removed via methanogenesis and sulfidogenesis and the COD/SO₄²⁻ ratio was found, indicating that the increase of this ratio is beneficial to the methanogenic archaea activity. The occurrence of sulfidogenesis, favored by the lower COD/SO₄²⁻ ratios, induced the microbial soluble products (SMP) and extracellular polymeric substances (EPS) release and protein/carbohydrate ratio increase in the mixed liquor, contributing to the filtration resistance increase.
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