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17361. 题目: Examining the effectiveness of biomass-derived biochar for the amelioration of tropospheric ozone-induced phytotoxicity in the Indian wheat cultivar HD 2967
文章编号: N20122614
期刊: Journal of Hazardous Materials
作者: Annesha Ghosh, Madhoolika Agrawal, Shashi Bhushan Agrawal
更新时间: 2020-12-26
摘要: A pot study was performed to evaluate the influence of O3 stress with different biochar treatments on a wheat cultivar (HD 2967). Plants were subjected to ambient and elevated (ambient+20 ppb) O3 along with three doses of biochar (0, 2.5, and 5%). Elevated ozone alone reduced most of the growth parameters, negatively affecting the test cultivar's physiology. Although enzymatic antioxidants were up-regulated by elevated O3, damage to the membrane integrity was evident by higher MDA content in the wheat leaves. Besides, the uptake of nutrients was observed to be reduced under elevated O3 due to the reduced phyto-availability of the soil's nutrients and cation exchange capacity. Such limitation of assimilates and nutrients marked a trade-off between growth and defence, translating to grain yield loss. However, applying biochar as a soil conditioner ameliorated the detrimental effects of O3 with respect to the economic yield of wheat. Biochar alone improved soil properties and nutrient phyto-availability, which translated to better plant growth, stronger physiological capacity, and higher crop productivity. Thus, the study inferred that altered nutrient phyto-availablity and its uptake, likely associated with biochar-induced improved soil properties, relayed stronger plant physiology and antioxidative defence system to combat O3 induced oxidative stress.

17362. 题目: Contribution of microalgae to carbon sequestration in a natural karst wetland aquatic ecosystem: an in-situ mesocosm study
文章编号: N20122613
期刊: Science of The Total Environment
作者: Zhuang Yan, Taiming Shen, Wei Li, Wenli Cheng, Xiayu Wang, Min Zhu, Qiwen Yu, Yutian Xiao, Longjiang Yu
更新时间: 2020-12-26
摘要: Carbonate rock weathering coupled with aquatic photosynthesis in karst areas is an important part in the formation of terrestrial carbon sinks. The capacity of photosynthetic carbon sequestration by aquatic microalgae and carbonic anhydrase (CA) is integral in the estimation of carbon sink potential of karst aquatic ecosystems. To date, carbon sequestration by aquatic microalgae in karst areas has been investigated in laboratory experiments. In the present work, the capacity of carbon sequestration by microalgae and CA under natural karst aquatic conditions and the main environmental factors were investigated in field in-situ mesocosms. The Sizhitan Pond of the Huixian karst wetland in Guilin City, Guangxi Province, China, was selected as a typical karst natural water body for this study. The capacity of photosynthetic carbon sequestration varied with microalgal community composition. The microalgal communities with active extracellular CA showed high capacity of carbon sequestration. The average conversion of inorganic carbon to relatively stable organic carbon by microalgae in the Huixian karst wetland aquatic ecosystem was estimated as 4207.5 t C/a. Approximately 28.7% of the bicarbonate fed by the karst underground river was fixed into organic carbon by microalgal photosynthesis. The major environmental factors affecting the capacity of carbon sequestration by microalgae in the karst wetland aquatic ecosystem were the water CA activity, illumination, temperature, total phosphorus and total nitrogen. This study is the first to address the contribution of aquatic microalgae and CA to carbon sequestration under natural karst aquatic conditions. The findings contribute to establishing groundwork for substantiating the carbon sink potential in global karst ecosystems.

17363. 题目: Forest management practices of Pinus tabulaeformis plantations alter soil organic carbon stability by adjusting microbial characteristics on the Loess Plateau of China
文章编号: N20122612
期刊: Science of The Total Environment
作者: Yahui Song, Jiaying Zhai, Jiaoyang Zhang, Leilei Qiao, Guoliang Wang, Lihui Ma, Sha Xue
更新时间: 2020-12-26
摘要: Sustainable management practices can enhance the capacity and potential for soil carbon (C) sequestration, significantly contributing towards mitigating regional climate change. Here, we investigated how the microbial characteristics of a Pinus tabulaeformis plantation responded to different management practices to identify the role of microbial characteristics in influencing the stability of soil organic carbon (SOC). We chose a Pinus tabulaeformis plantation on the Loess Plateau where forest management practices had been conducted since 1999. Five forest management practices were implemented: two at the forest level (P. tabulaeformis with and without ground litter), and three using different vegetation restoration approaches after clear-cutting (P. tabulaeformis seedlings, abandoned grassland, and natural shrub regeneration). Microbial biomass, soil respiration, microbial community structure, microbial metabolic function, and soil oxidizable organic carbon (OC) fractions were evaluated. Forest management practices changed SOC stability by adjusting the microbial characteristics (e.g. soil microbial community diversity and microbial metabolic function diversity). The result of path analysis was that the direct path coefficient of microbial biomass on soil oxidizable OC fractions was the largest, which was 1.499. Path analysis and redundancy analysis showed that microbial biomass had the largest direct influence on soil oxidizable OC fractions. Compared with other forest management practices, natural shrub regeneration increased the nonlabile carbon fraction by increasing soil microbial characteristics, and contributed the most towards stabilizing SOC, which enhanced the stability of the soil ecosystem on the plateau. In conclusion, microbial biomass was the biggest influence factor of SOC stability. In contrast, the stability of SOC may be most stable in the area of natural shrub regeneration.

17364. 题目: Microbial carbon use efficiency, biomass residence time and temperature sensitivity across ecosystems and soil depths
文章编号: N20122611
期刊: Soil Biology and Biochemistry
作者: Jinquan Li, Junmin Pei, Feike.A. Dijkstra, Ming Nie, Elise Pendall
更新时间: 2020-12-26
摘要: Decomposition of soil organic matter by microorganisms is a fundamental mechanism driving the terrestrial carbon (C) cycle. Microbial C use efficiency (CUE), microbial biomass residence time (MRT), and soil C temperature sensitivity (Q10) co-determine the fate of soil C in a changing climate. In order to reveal the effect of soil depth and varying hydrologic properties on CUE, MRT, and Q10 of microbial respiration, we incubated soils from three ecosystems (wetland, grassland, and forest) and soil depths (0–10, 20–30, and 50–60 cm) at two temperatures (10 and 30°C). Microbial CUE was estimated using a substrate-independent method by incorporating 18O from labeled water into microbial DNA with the simultaneous measurement of microbial respiration. CUE ranged from about 0.2 to 0.7 with a mean value of 0.5 ± 0.1, MRT ranged from 4 to 73 days with a mean value of 26 ± 19 days, and Q10 ranged from 1.8 to 2.9, averaging 2.3 ± 0.3 across all samples. We found that CUE increased but MRT and Q10 decreased along the wetland-grassland-forest hydrologic gradient; and they all increased with soil depth. Moreover, CUE and MRT were lower at 30°C than that at 10°C. Although there were some differences in factors regulating the variation in CUE, MRT or Q10 among soil depths and ecosystem types, both within individual ecosystems and depths, CUE, MRT, and Q10 were strongly correlated to available C:N ratios, clay content, and C quality, respectively. In conclusion, our findings emphasize the importance of stoichiometry and C quality of available substrates in predicting the variation in microbial C use efficiency and soil C temperature sensitivity in different soil depths and along a hydrologic gradient.

17365. 题目: Adsorption of gold from waste mobile phones by biochar and activated carbon in gold iodized solution
文章编号: N20122610
期刊: Waste Management
作者: Wanying Zhou, Huiting Liang, Yuanye Lu, He Xu, Yongli Jiao
更新时间: 2020-12-26
摘要: The application of laboratory-generated biochar and activated carbon adsorbents in gold iodized solution for the recycling of waste mobile phone printed circuit boards (WMPCBs) is investigated. This research aims to solve problems associated with the existing gold recovery technologies of WMPCBs. Currently, the disposal of WMPCBs is expensive, involves complex processes, and contributes to secondary pollution. In this study, laboratory-generated biochar is produced from corn straw, wheat straw, and wood chips by pyrolysis. The effects of factors on the adsorption efficiency are investigated, and the optimal operating conditions for biochar and activated carbon adsorption are determined. The following optimal parameters were found for activated carbon: temperature = 25 °C, particle size = 40–60 mesh, dosage = 0.05 g/10 mL, pH = 7, reaction time = 2 h, and oscillation frequency = 200 r/min. The adsorption efficiency reached 98.6%. For biochar, optimization involved: raw material from corn straw at a pyrolysis temperature = 700 °C, reaction time = 5 h, oscillation frequency = 200 r/min, pH = 3, dosage = 0.15 g/10 mL, and temperature = 50 °C. An adsorption efficiency of 98% was achieved. The two adsorbents were compared, and results demonstrated that the adsorption properties of the laboratory-generated biochar were slightly inferior to those of the activated carbon; however, they were similar. Biochar adsorption can reuse waste, which may not only solve the current problems related to WMPCB recycling, but can help to achieve a win-win situation of increased environmental protection and sustainable utilization of resources.

17366. 题目: Comparative analysis for pyrolysis of sewage sludge in tube reactor heated by electromagnetic induction and electrical resistance furnace
文章编号: N20122609
期刊: Waste Management
作者: Yongjie Xue, Yi Zhou, Jian Liu, Yue Xiao, Teng Wang
更新时间: 2020-12-26
摘要: A comparative study was conducted on the pyrolysis of sewage sludge in tube reactors heated by electromagnetic induction (EMI) and conventional electrical resistance furnace (ERF). A minimal effect of pyrolysis temperature and initial moisture content on the distribution of pyrolytic products was obtained. Compared with the counterpart from ERF pyrolysis, the bio-char from EMI pyrolysis exhibited less ash content (46.38 wt%) and higher organic matter content (53.62 wt%). SEM and FTIR test showed similar microstructure characterizations in the two bio-chars. The specific area of bio-char from EMI pyrolysis was 8.6 m2/g. EMI pyrolysis increased the total content of aliphatic/aromatics in the bio-oil from 10.8 wt% to 15.6 wt% and the hydrogen/carbon monoxide in the bio-gas from 33.8 vol% to 41.1 vol% because of possible cracking and reforming reactions. Increased sulfur content in the bio-oil and decreased hazard gas content (such as hydrogen sulfide and sulfur dioxide) in the bio-gas were obtained during EMI pyrolysis. The actual energy consumption for EMI and ERF pyrolysis were 4.62 MJ/kg and 6.65 MJ/kg. Increasing the feedstock content would reduce the energy consumption unit energy consumption. Less system energy loss during EMI pyrolysis might explain the higher energy recovery from EMI pyrolysis than that from ERF. Despite some disadvantages, EMI pyrolysis shows potential in real-plant applications.

17367. 题目: Soil aggregates are key factors that regulate erosion-related carbon loss in citrus orchards of southern China: Bare land vs. grass-covered land
文章编号: N20122608
期刊: Agriculture, Ecosystems & Environment
作者: J.Y. Zheng, J.S. Zhao, Z.H. Shi, L. Wang
更新时间: 2020-12-26
摘要: Water erosion induces a wide variation in organic carbon (OC) loss in orchard agroecosystems due to high anthropogenic disturbance. Grass cover, a common agricultural practice, can both suppress OC transport by reducing erosive rainfall and runoff, and enhance the amount of OC in soil by increasing OC inputs. These different effects on OC loss call for a deeper understanding of the process and drivers of OC loss under grass cover during water erosion processes. Hence, we conducted a simulated rainfall experiment under bare land (BL) and grass cover in orchards to analyse the direct and indirect effects of grass cover, soil aggregate properties, runoff and sediment yield on OC loss using structural equation modelling (SEM). The results demonstrated that grass cover reduced sediment and runoff by 97.84–98.81 % and 47.28–82.12 %, respectively, and correspondingly reduced the loss of 97.21–99.24 % soil organic carbon (SOC) and 83.55–92.76 % dissolved organic carbon (DOC) compared to BL. The SEM results showed that sediment, as opposed to runoff, was the main pathway of OC loss and grass cover regulated total organic carbon (TOC) loss by varying soil aggregate properties rather than by changing erosive forces. Specifically, the total effect of the soil aggregate stability and SOC content in aggregates under grass cover on TOC loss was negative (-0.21 and -1.14, respectively). Moreover, the increasing percentage of >5 mm soil aggregates contributed to reducing SOC and DOC losses, while the increasing percentage of 0.5−0.25 mm soil aggregates aggravated SOC and DOC losses. The results from this study emphasize that grass cover is a convenient and effective measure for reducing OC loss in orchards; moreover, studying the effect of multiple-factor interactions on OC loss will provide insights and improve predictions of the global carbon cycle.

17368. 题目: Effects of long-term biochar and biochar-based fertilizer application on brown earth soil bacterial communities
文章编号: N20122607
期刊: Agriculture, Ecosystems & Environment
作者: Mengyu Gao, Jinfeng Yang, Chunmei Liu, Bowen Gu, Meng Han, Junwei Li, Na Li, Ning Liu, Ning An, Jian Dai, Xiaohua Liu, Xiaori Han
更新时间: 2020-12-26
摘要: The objective of this study was to investigate the effects of 6 years of continuous biochar and biochar-based fertilizer (BBF) application on the soil bacterial community of brown earth soil (Cambisol) growing peanuts. There were five treatments: no fertilizer, low biochar (LB, 250 kg ha−1), high biochar (HB, 750 kg ha−1), chemical nitrogen (N)–phosphorus (P)–potassium (K) fertilizer (NPK, 83 kg ha−1 N, 36 kg ha−1 P, and 41 kg ha−1 K), and BBF (750 kg ha−1). The community richness (ACE) and community diversity (Shannon) indices were highest in the HB treatment, and the ACE of the HB treatment was higher than in the LB treatment (15.4 %). Proteobacteria was the dominant phylum (more than 38.5 % in all treatments). Compared to the CK and NPK treatments, Acidobacteria increased, and Actinobacteria decreased with biochar addition, but there were no significant differences in the microbial community structures of the biochar treatments (LB, HB, and BBF). The soil pH, total nitrogen, and available phosphorus were significantly associated with the bacterial community composition (phyla level). Cell wall/membrane/envelope biogenesis, signal transduction mechanisms, amino acid transport and metabolism, and energy production and conversion were the main gene types. The genes related to energy production and conversion, amino acid transport, metabolism, nucleotide transport and metabolism, carbohydrate transport and metabolism, and other functional roles were significantly more abundant in the biochar treatments (LB, HB, BBF) than in the CK and NPK treatments.

17369. 题目: The influence of amino acids structure on their anaerobic digestion and the strategy to enhance biotransformation of refractory ones
文章编号: N20122606
期刊: Chemical Engineering Journal
作者: Meng Wang, Tong Yu, Yang Huo, Yinguang Chen
更新时间: 2020-12-26
摘要: Protein is an important component of organic waste, and it is first hydrolyzed to amino acids (AAs) during anaerobic digestion (AD). Until now, however, the effect of AAs structure on their AD has never been documented. In this paper the influence of AAs structure on their two-phase AD and the strategy to enhance biotransformation of refractory ones were investigated. Firstly, the AD performance of nineteen water-soluble AAs was compared. The methane yield of polar AAs was higher than that of non-polar ones (162.3–308.1 verse 10.7–140.5 mL/gCODadd) except glycine (284.1 mL/gCODadd). Further studies showed that the order of methane production with polar AAs, according to their carbon number, was 4-C < 6-C < 3-C < 5-C, while that with non-polar AAs was long-chain AAs (5 to 11-C) < short-chain AAs (2 to 3-C). The methane yield of non-polar ones with long-chain, according to their functional groups, was followed: proline > Alkyl AAs > Ph AAs. The mechanism investigation revealed the relationship between the structure of AAs and the amount of VFAs excluding propionate was consistent with the influence of AAs structure on methane yield. The microbes in AD system of refractory AAs had higher cell surface hydrophobicity (CSH) and lower cell membrane permeability (CMP), which led to lower enzyme activities and amino acid degradation as well as VFAs generation, and thus less methane production. Finally, the strategy to increase the biotransformation of refractory AAs was studied, and the methane yield was increased up to 139.8% by the application of rhamnolipid to change CSH and CMP in the digestion system. These findings elucidated the relationship between AAs structure and AD performance and provided new ideas to improve the biotransformation of refractory AAs.

17370. 题目: Predicting dissolved organic carbon concentration in a dynamic salt marsh creek via machine learning
文章编号: N20122605
期刊: Limnology and Oceanography: Methods
作者: Christina J. Codden, Andrew M. Snauffer, Amy V. Mueller, Catherine R. Edwards, Megan Thompson, Zachary Tait, Aron Stubbins
更新时间: 2020-12-26
摘要: Dissolved organic carbon (DOC) is a master variable in aquatic systems. Resolving DOC dynamics requires high‐temporal resolution data. However, DOC concentration cannot be directly measured in situ, and discrete sample collection and analysis becomes expensive as temporal resolution increases. To surmount this problem, an option is to predict site‐specific DOC concentration with linear modeling and optical data predictors collected from high‐cost, high‐maintenance in situ spectrophotometers. This study sought to improve upon the accuracy and field costs of linear predictive DOC methods by using machine learning modeling coupled to low‐to‐zero cost predictors. To do this, we collected 16 months of in situ data (e.g., spectrophotometer attenuation, salinity, temperature), assembled freely available predictors (e.g., point in year, rainfall), and collected samples for DOC analysis, all in a salt marsh creek. At seasonal timescales, machine learning (coefficient of determination [R2] = 0.90) modestly improved upon the accuracy of linear methods (R2 = 0.80) but offered substantial instrumentation cost reductions (~ 90%) by requiring only cost‐free predictors (online data) or cost‐free predictors paired with low‐cost in situ predictors (temperature, salinity, depth). At intertidal timescales, linear methods proved ill‐equipped to predict DOC concentration compared to machine learning, and again, machine learning offered a substantial instrumentation cost reduction (~ 90%). Although our models were developed for and applicable to a single site, the use of machine learning with low‐to‐zero cost predictors provides a blueprint for others trying to model DOC dynamics and other analytes in any complex aquatic system.

17371. 题目: Formation factors and hazard evaluation of halogenated methyl sulfonic acid in drinking water
文章编号: N20122604
期刊: Environmental Research
作者: Tong Zhu, Shipeng Yang, Xiaohang Zhang, Xiaoling Zhao, Kaijun Wang
更新时间: 2020-12-26
摘要: Halogenated methyl sulfonic acid (HMSAs) is a new type of disinfection by-product recently reported, and there are few relevant studies, so its source and harm are still unclear. This study mainly discusses the source of halogenated methyl sulfonic acid from the macroscopic level and evaluates the harm to human health. This study clarified that chlorine disinfection is one of the main ways of generating halogenated methyl sulfonic acids (HMSAs) in drinking water. The macroscopic properties of HMSA precursors were analyzed through liquid chromatograph-mass spectrometry (LC-MS/MS), 3D fluorescence, and Fourier transform infrared spectrometry. The results showed that polar and positively charged organic compounds with molecular weights of >3 KDa or <0.5 KDa can readily generate HMSAs. By analyzing the main components of natural organic compounds in water and comparing them with the characteristics of organic compounds such as dimethyl sulfoxide and ethyl mercaptan, it meant that natural organic compounds are easily degraded. Humic and fulvic acids contribute the most to HMSA generation. This study lasted for three years and collected water samples from 102 waterworks in 24 cities in China, and the existence of HMSAs in drinking water in different cities was analyzed. The potential health risks associated with HMSAs were used by the United States Environmental Protection Agency (U.S. EPA) health risk assessment model. The average and maximum concentrations of HMSAs in tap water from key cities in China were taken as evaluation objects. The results showed that the carcinogenic risk coefficient (R) value of both concentrations was far lower than the lowest acceptable carcinogenic risk (1.0×10-6) provided by U.S. EPA. Therefore, HMSAs in drinking water in China currently pose no human health risks.

17372. 题目: Successful remediation of soils with mixed contamination of chromium and lindane: Integration of biological and physico-chemical strategies
文章编号: N20122603
期刊: Environmental Research
作者: Juan Daniel Aparicio, Rafael G. Lacalle, Unai Artetxe, Erik Urionabarrenetxea, José María Becerril, Marta Alejandra Polti, Carlos Garbisu, Manuel Soto
更新时间: 2020-12-26
摘要: Soils contaminated by organic and inorganic pollutants like Cr(VI) and lindane, is currently a main environmental challenge. Biological strategies, such as biostimulation, bioaugmentation, phytoremediation and vermiremediation, and nanoremediation with nanoscale zero-valent iron (nZVI) are promising approaches for polluted soil health recovery. The combination of different remediation strategies might be key to address this problem. For this reason, a greenhouse experiment was performed using soil without or with an organic amendment. Both soils were contaminated with lindane (15 mg kg-1) and Cr(VI) (100 or 300 mg kg-1). After one month of aging, the following treatments were applied: (i) combination of bioaugmentation (actinobacteria), phytoremediation (Brassica napus), and vermiremediation (Eisenia fetida), or (ii) nanoremediation with nZVI, or (iii) combination of biological treatments and nanoremediation. After 60 days, the wellness of plants and earthworms was assessed, also, soil health was evaluated through physico-chemical parameters and biological indicators. Cr(VI) was more toxic and decreased soil health, however, it was reduced to Cr(III) by the amendment and nZVI and, to a lesser extent, by the biological treatment. Lindane was more effectively degraded through bioremediation. In non-polluted soils, nZVI had strong deleterious effects on soil biota when combined with the organic matter, but this effect was reverted in soils with a high concentration of Cr(VI). Therefore, under our experimental conditions bioremediation might be the best for soils with a moderate concentration of Cr(VI) and organic matter. The application of nZVI in soils with a high content of organic matter should be avoided except for soils with very high concentrations of Cr(VI). According to our study, among the treatments tested, the combination of an organic amendment, biological treatment, and nZVI was shown to be the strategy of choice in soils with high concentrations of Cr (VI) and lindane, while for moderate levels of chromium, the organic amendment plus biological treatment is the most profitable treatment.

17373. 题目: Methylmercury Transport and Fate Shows Strong Seasonal and Spatial Variability along a High Arctic Freshwater Hydrologic Continuum
文章编号: N20122602
期刊: Environmental Science & Technology
作者: Stephanie Varty, Igor Lehnherr, Kyra St. Pierre, Jane Kirk, Victoria Wisniewski
更新时间: 2020-12-26
摘要: The presence of toxic methylmercury (MeHg) in Arctic freshwater ecosystems and foodwebs is a potential health concern for northern Indigenous people. Addressing this issue requires a better understanding of MeHg production, fate during transport, and uptake into foodwebs. We used methylation assays and spatiotemporal surveys of MeHg concentrations, during the ice-covered and open water seasons, across a hydrologic continuum (composed of thaw seeps, lake/ponds, and a wetland) to identify Hg methylation hotspots and seasonal differences in MeHg cycling unique to Arctic ecosystems. Ponds and saturated wetland soils support methylation hotspots during the open water season, but subsequent export of MeHg to downstream ecosystems is limited by particle settling, binding of MeHg on soil organic matter, and/or demethylation in drier wetland soils. During the ice-covered season, MeHg concentrations in lake waters were approximately ten-fold greater than in summer; however, zooplankton MeHg concentrations were paradoxically five times lower at this time. Despite limited evidence of snow-phase methylation, the snowpack is an important MeHg reservoir. Changes in ice-cover duration will alter MeHg production and bioaccumulation in lakes, while increased thaw and surface water flow will likely result in higher methylation rates at the aquatic–terrestrial interface and more efficient downstream transport of MeHg.

17374. 题目: Factors Affecting Nitrate Concentrations in Stream Base Flow
文章编号: N20122601
期刊: Environmental Science & Technology
作者: Susan A. Wherry, Anthony J. Tesoriero, Silvia Terziotti
更新时间: 2020-12-26
摘要: Land use, geology, and riparian canopy are indicated as factors affecting nitrate concentrations in stream base flow. Much of this nitrogen is derived as nitrate from groundwater that discharges to streams as base flow. In this study, boosted regression trees (BRTs) were used to relate nitrate concentrations in base flow (n = 156) to explanatory variables describing nitrogen sources, geology, and soil and catchment characteristics. From these relations, a BRT model was developed to predict base flow nitrate concentrations in streams throughout the Chesapeake Bay watershed. The highest base flow nitrate concentrations were associated with intensive agricultural land use, carbonate geology, and sparse riparian canopy, which suggested that reduced nitrogen inputs, particularly over carbonate terrane, are critical for limiting nitrate concentrations. The lowest nitrate concentrations in the BRT model were associated with extensive riparian canopy, high levels of organic carbon in soils, and suboxic conditions at shallow depths, which suggested that denitrification in the subsurface, particularly in the riparian zone, is limiting base flow nitrate concentrations. Nitrate transport from aquifers to streams can take decades to occur, resulting in decades-long lag times between the time when a land-use activity is implemented and when its effects are fully observed in streams. Predictive models of base flow nitrate concentrations in streams will help identify which portions of a watershed are likely to have large fractions of total stream nitrogen load derived from pathways with significant lag times.

17375. 题目: Adsorption recovery of phosphate from waste streams by Ca/Mg-biochar synthesis from marble waste, calcium-rich sepiolite and bagasse
文章编号: N20122508
期刊: Journal of Cleaner Production
作者: Wangde Deng, Dongqing Zhang, Xiaoxian Zheng, Xingyao Ye, Xiaojun Niu, Zhang Lin, Mingli Fu, Shaoqi Zhou
更新时间: 2020-12-25
摘要: In this study, marble waste and calcium-rich sepiolite were employed as Ca and Mg sources, and the agricultural waste was used as carbon source to synthesize two modified-biochar composites (Mar-BC800 and Sep-BC800) for removing phosphate from waste streams. The results show that Mar-BC800 and Sep-BC800 exhibited excellent performance for phosphate adsorption from aqueous solution in a wide pH range of 3-11, and the maximum adsorption capacity of phosphate by Mar-BC800 and Sep-BC800 was 263.17 and 128.21 mg/g, respectively. The adsorption process was best described by the pseudo second-order model and Langmuir model, and the dominating sorption mechanism for phosphate is that Ca2+ or Mg2+ with phosphate to form Ca5(PO4)3OH, Mg3(PO4)2 and Mg3(PO4)2·4H2O precipitate. Furthermore, Mar-BC800 and Sep-BC800 are simple to produce, the methods used to produce modified biochar are green, economic and environmentally-friendly, and the phosphate adsorbed modified biochar can applied as fertilizer to farmland soil, which have the functions of increasing soil fertility and improving soil physical and chemical properties.

17376. 题目: Self-decoration of N-doped graphene oxide 3-D hydrogel onto magnetic shrimp shell biochar for enhanced removal of hexavalent chromium
文章编号: N20122507
期刊: Journal of Hazardous Materials
作者: Mohamed E. Mahmoud, Asmaa K. Mohamed, Mohamed Abdel Salam
更新时间: 2020-12-25
摘要: In this work, a novel decorated and combined N-doped graphene oxide hydrogel with shrimp shell magnetic biochar (NGO3DH-MSSB) biosorbent was fabricated as an effective material for Cr(VI) removal. Three-dimensional self-assembled graphene oxide hydrogel was synthesized using nitrogen source, ethylenediamine (EDA). Characterizations of NGO3DH-MSSB biosorbent were established by FT-IR, TGA, SEM and BET, where high surface area (398.05 m2/g) compared with that of MSSB (138.64 m2/g) was characterized. The maximum achieved swelling ratio (800%) was only after 300 min. The binding mechanisms between Cr(VI) ions and NGO3DH-MSSB biosorbent were controlled by electrostatic adsorption (ion-pair), pore filling, and reduction-coordination reaction. Adsorption was described by the pseudo-second order kinetic (R2 = 0.9994, 0.9983 and 0.9992) at 10, 50 and 100 mg/L and Langmuir isotherm model (R2 = 0.9997, 0.9957 and 0.9912) at 25, 40 and 50 oC. The adsorption capacity (350.42 mg/g) was achieved at pH 1.0, using initial Cr(VI) concentration (100 mg/L) and contact time (180 min) at room temperature. NGO3DH-MSSB biosorbent could be successfully reused after eight cycles. The percentage removal of Cr(VI) were confirmed as 99.79, 99.20 and 98.0% from tap water, sea water and wastewater, respectively.

17377. 题目: Synthesis of Fe0/Fe3O4@porous carbon through a facile heat treatment of iron-containing candle soots for peroxymonosulfate activation and efficient degradation of sulfamethoxazole
文章编号: N20122506
期刊: Journal of Hazardous Materials
作者: Yating Yan, Huayu Zhang, Wei Wang, Wenchao Li, Yueping Ren, Xiufen Li
更新时间: 2020-12-25
摘要: Developing highly efficient, reusable, non-toxic and low-cost catalysts is of great importance for persulfate-based advanced oxidation processes (AOPs). In this work, ferrocene was mixed into paraffin to prepare a candle, and the iron-containing candle soots were collected and heated at 500 oC~900 oC under N2 atmosphere for 1 h to prepare magnetically recyclable Fe0/Fe3O4@porous carbon (Fe0/Fe3O4@PC) catalysts. The Fe0/Fe3O4@PC-700 obtained after pyrolysis at 700 oC exhibited the best catalytic activity for sulfamethoxazole (SMX) degradation. 10 mg/L SMX could be completely degraded within 10 min by 0.2 g/L of Fe0/Fe3O4@PC-700 and 0.5 mM PMS at pH 5.0. The carbon shell effectively inhibited the Fe leaching of Fe0/Fe3O4@PC-700, and 99.73% of Fe was retained after five consecutive cycles. In the Fe0/Fe3O4@PC-700/PMS system, SMX was degraded through the sulfate radical (SO4·¯), hydroxyl radical (·OH), superoxide radical (O2·¯) dominated radical pathway, and the singlet oxygen (1O2) dominated non-radical pathway. The coexisting inorganic ions and natural organic matters (NOM) in actual water inhibited the degradation of SMX. Finally, four possible degradation pathways were proposed based on the degradation intermediates of SMX. This work provides a facile heat treatment of iron-containing candle soots strategy to prepare the [email protected] catalysts for PMS-based AOP.

17378. 题目: Periphyton enhances arsenic release and methylation at the soil-water interface of paddy soils
文章编号: N20122505
期刊: Journal of Hazardous Materials
作者: Ting Guo, Williamson Gustave, Haiying Lu, Yan He, Xianjin Tang, David B. Buchwalter, Jianming Xu
更新时间: 2020-12-25
摘要: Periphyton is ubiquitous in rice paddy fields, however its role in paddy soil arsenic (As) biogeochemistry remains unexplored. In this study, microcosm incubations and extensive field sampling were used to better understand the roles of periphyton on As mobility and transformation at the soil-water interface. Microcosm incubations revealed that periphyton on the paddy soil surface enhanced As release to water and increased methylated As contents at the soil-water interface. Experimental additions of dissolved phosphate did not significantly affect these processes. The presence of periphyton increased the dissolved organic carbon (DOC) content of the surface soil which may have played a role in the increased As mobility. However, the increase in methylated As species at the soil-water interface is indicative of detoxification processes of As by periphyton. The results from the field study revealed a high abundance and diversity of As biotransformation and detoxification genes in periphyton. Genera of Kineosporia, Limisphaera, Ornatilinea, Ktedonosporobacter and Anaerolinea played key roles in shaping arsM harboring microbe communities in field periphyton. These results highlight the importance of periphyton in the behavior of As in paddy soils and can potentially facilitate improved management of As contamination in paddy soils.

17379. 题目: Heterogeneous Fenton-like reaction followed by GAC filtration improved removal efficiency of NOM and DBPs without adjusting pH
文章编号: N20122504
期刊: Separation and Purification Technology
作者: Yao Zhang, Zhili Lu, Zeyu Zhang, Baoyou Shi, Chun Hu, Lai Lyu, Pengxiao Zuo, Jordin Metz, Haibo Wang
更新时间: 2020-12-25
摘要: This paper explores the removal of natural organic matter (NOM) and disinfection by-products (DBPs) in drinking water by heterogeneous Fenton-like oxidation and granular activated carbon (GAC) filtration in a pilot scale test without adjusting pH of the water. pH of the used water in this study was from 7.5 to 8.7. Comparing with conventional water treatment processes, heterogeneous Fenton-like reaction and GAC filtration increased the removal rate of dissolved organic carbon (DOC), NOM with different apparent molecular weight (AMW) (F1-F7) and with different compositions (C1-C5) to 75.11%, 88.65% and 58.73%, respectively. Moreover, heterogeneous Fenton-like reaction and GAC filtration increased the removal rate of DBPs to 88.18%. The multivariate statistical analysis indicated that haloacetic acids (HAAs) and haloketones (HKs) mainly came from fulvic-like and humic-like NOM with AMW lower than 1.5 K Da. These substances with AMW between 1.5 K Da and 3.5 K Da were the main precursors of trihalomethanes (THMs). The main precursors of halonitriles (HANs) were soluble microbial byproduct-like (SMP-like), tyrosine-like and tryptophan-like substance with the AMW between 3.5 K Da and 4.5 K Da. Overall, without adjusting pH of water, heterogeneous Fenton-like reaction and GAC filtration improved the removal efficiency of NOM and DBPs, and controlled the genotoxicity of drinking water.

17380. 题目: Addition of wheat straw to acid sulfate soils with different clay contents reduces acidification in two consecutive submerged-moist cycles
文章编号: N20122503
期刊: Geoderma
作者: N. Jayalath, Rob Fitzpatrick, Luke M. Mosley, Petra Marschner
更新时间: 2020-12-25
摘要: Acid sulfate soils (ASS) are wide-spread in wetlands and experience distinct biogeochemical changes during submerged and moist periods. During submerged periods, under reducing conditions, sulfate reduction can result in a pH increase whereas moist periods induce sulfide and ferrous iron oxidation, leading to acidification which can pose a threat to the environment. A laboratory incubation experiment was carried out to determine the effect of organic matter (OM) amendment on pH and redox potential over two successive submerged-moist cycles in different types of ASS (Sulfuric, Hypersulfidic and two Hyposulfidic soils). The four soils also differed in clay content (10, 15, 23, 38% referred to as C10, C15, C23 and C38) and were collected in a wetland at Banrock Station, South Australia. The experiment was conducted over 24 weeks with each submerged and each moist period lasting 6 weeks. The soils were unamended or amended with 10 g C kg−1 finely ground wheat straw. During the submerged periods, the soils were maintained under a layer of water, in the moist periods they were kept at 100% of water holding capacity. The soil pH increased in both submerged periods, particularly in amended soils with low clay content (C10 and C15). Changes in pH during submerged and moist periods were greater in soils with low clay content (C10, C15) than those with high clay content (C23, C38). The effect of wheat straw addition on pH at the end of submerged and moist periods did not differ between the two submerged-moist periods, with a higher pH in amended than unamended soils. In submerged periods, the redox potential (Eh) decreased more strongly in amended soils than in unamended soils. It was 100–200 mV from week 2 onwards in amended soils whereas the Eh was 300 to 400 mV higher without amendment except in C38 where it was 100–200 mV in both amendment treatments. In the moist periods, the pH decreased more strongly in amended than in unamended soils, particularly in C10 and C15 but remained higher than in unamended treatments. This study showed that wheat straw addition maintains its ameliorative effect on soil pH for at least two submerged-moist cycles, but the ameliorative pH effect depends on clay content, being greater in soils with low clay content.