This study designed surface flow constructed wetlands (SFCWs) with Myriophyllum aquaticum (M. aquaticum) to evaluate how different influent C/N ratios (0:1 (C0N), 5:1 (C5N), 10:1 (C10N), and 15:1 (C15N)) affect pollutant removal, greenhouse gas (GHG) emissions, and microbial communities. The results showed that effluent ammonia nitrogen (NH4+-N), nitrate nitrogen (NO3−-N), and total nitrogen (TN) concentrations decreased, but effluent chemical oxygen demand (COD) concentration increased with increasing influent C/N ratios. The highest removal rates of TN (73.17%) and COD (74.56%) were observed with C5N. Regarding GHG emissions, a few changes in CO2 fluxes were caused by the influent C/N ratio, whereas CH4 fluxes obviously increased with the increasing influent C/N ratio. The highest N2O emission occurred with C0N (211.03 ± 44.38 mg-N·m−2·h−1), decreasing significantly with higher C/N ratios. High-throughput sequencing revealed that different influent C/N ratios directly influenced the microbial distribution and composition related to CH4 and N2O metabolism in SFCWs. The highest abundance (46.24%) of denitrifying bacteria (DNB) was observed with C5N, which helped to achieve efficient nitrogen removal with a simultaneous reduction in N2O emissions. Methanogen abundance rose with higher C/N ratios, whereas methanotrophs peaked under C5N and C10N conditions. Additionally, the random forest model identified influent C/N ratio and Rhodopseudomonas as primary factors influencing CH4 and N2O emissions, respectively. This highlights the importance of the influent C/N ratio in regulating both pollutant removal and GHG emissions in constructed wetlands.

Excessive application of chemical fertilizers accumulates nitrogen in soil (soil legacy nitrogen), and its release has a long-term impact on environmental quality. The information regarding leaching of soil legacy nitrogen and role of soil pore structure is scarce. Fifteen undisturbed soil cores with a depth of ~200 mm were collected from five paddy fields in a subtropical area of China, and soil pore structure was characterized with X-ray computed tomography. The batch leaching column experiments were conducted to investigate the nitrogen leaching from the soil cores. In the leachate, inorganic nitrogen (NO3--N and NH4+-N) accounted for 73-85 % of total dissolved nitrogen (TDN), which showed small variations among the five sampling sites. The NO3--N, NH4+-N and TDN concentrations in the leachate over the number of leaching times could be well fitted with the Gaussian, exponential or linear models, suggesting that different nitrogen forms showed variable leaching dynamics. NO3--N and TDN leaching losses continued to increase with the number of leaching times, whereas NH4+-N leaching from the soil had a threshold value. Combination of changes in soil nitrogen content after leaching, the lagging effect of soil legacy nitrogen may be partly attributed to the continuous transformation of NH4+-N and organic nitrogen into NO3--N in the soils. Besides the nitrogen content in the soil, the most important factor of soil pore structure controlling NO3--N and TDN leaching loss was the fractal dimension; NH4+-N was mainly controlled by connectivity. The present study highlighted the importance of soil pore structure and nitrogen format transformation in the leaching of soil legacy nitrogen.

为探讨养殖废水中兽用抗生素对湿地系统中氮素转化及相关微生物过程的影响,以养殖废水中常见的抗生素SD(磺胺嘧啶)为例,设置0、10、100和1000μg∕L 4个添加浓度开展模拟试验.通过qPCR(实时荧光定量PCR)技术,测定了湿地底泥中氨氧化和反硝化功能基因丰度,结合Pearson相关分析,分析了养殖废水中不同氮素形态与底泥中氮转化功能基因丰度的关联性.结果表明:①与CK组比较,添加SD对湿地TN的最终去除效果无显著性差异,4个处理组的TN去除率为75.4％～80.5％,但在培养前期(0～14 d),SD对水体NH4+-N和NO3--N转化的抑制率最高分别达53.0％和99.5％,随着SD浓度的增加,抑制作用越强,到培养后期(14～28 d),各处理水体中不同形态的氮浓度无显著差异.②由qPCR测试结果得出,湿地底泥中AOA(氨氧化古菌)的丰度比AOB(氨氧化细菌)高出1～2个数量级,表明AOA在氨氧化过程中起主导作用,另外在培养第7天,AOB发生显著抑制现象,对SD更敏感;与CK相比,在第7天和第14天,反硝化基因narG、nirS、nirK和nosZ丰度随SD浓度的增加而逐渐降低.③相关性分析结果表明,AOA与ρ(NH4+-N)呈极显著正相关(P<0.01),AOB与ρ(NO3--N)呈极显著正相关(P<0.01),nirK与ρ(NO2--N)呈极显著正相关(P<0.01).研究显示,SD能抑制湿地底泥中氮转化微生物及相关氮转化过程,且SD浓度越大,抑制作用也越大,但随着培养时间的增加抑制作用会减弱.

Nitrogen dynamics were studied over 3 years in pilot-scale surface flow constructed wetlands (SFCWs) treating three strengths of ammonium-rich swine wastewater. A high removal rate of ammonium (1.2-2.9 g m(-2) d(-1)) and total nitrogen (1.5-3.5 g m(-2) d(-1)) was achieved from highstrength wastewater in the SFCWs. Nitrate concentration was significantly higher (p < 0.01) in the effluent than in the influent, and the increased nitrate concentration did not significantly affect ammonium removal in the SFCWs. The effluent nitrate concentration showed annual cyclical changes and could be described using a harmonic regression equation over time (y = a + b sin (2 pi/365.25 t + c); R-2 = 0.152-0.566). The multiple regression equation (R-2 = 0.200-0.551) indicated that water temperature and oxidation reduction potential were the primary factors affecting nitrate accumulation in the SFCWs. The abundance of nitrification functional genes (ampA in ammonia-oxidizing archaea and bacteria) was higher in spring and winter than in summer. The abundance of denitrification functional genes (narG, nirK, nirS, and nosZ) was higher in summer than in spring and winter. At cold temperatures (5-10 degrees C), nitrate accumulated significantly in the water column rather than in the sediments and the potential nitrification rates increased slightly, suggesting the importance of nitrogen transformation in the water column during nitrogen removal. These results are helpful for selecting targeted seasonal intensification strategies to improve the SFCWs performance.

In this study, the abundance and structure of bacterial and denitrifying functional genes of epiphyton and bacterioplankton in pilot-scale surface flow constructed wetlands treating different ammonium nitrogen concentrations (similar to 0.2, 40, 170, and 230 mg/L) of swine wastewater were investigated by quantitative PCR. The gene abundance of denitrifiers in epiphyton outnumbered the gene abundance of denitrifiers in bacterioplankton (P< 0.01), e.g., nirK gene abundance: 1.6-4.5 x 10(7) vs 0.23-1.5 x 10(4) copies/ng DNA. A nitrogen concentration-dependent microbial community structure was observed for epiphyton and bacterioplankton. Proteobacteria, Bacteroidetes, and Actinobacteria dominated at the phylum level in both epiphyton and bacterioplankton. The nirS gene abundance in both niches was negatively related to the dissolved oxygen and redox potential of wastewater, but it was positively related with the Bacteroidetes and Flavobacterium abundance. The results indicated that microbial community structure and abundance are distinct between epiphyton and bacterioplankton. This study also demonstrate that epiphytic biofilms play an important role in denitrification during the treatment of swine wastewater in constructed wetlands. Finally, since swine wastewater serves as an excellent source for nutrients, possible technological options including periphyton techniques for resource recovery from wastewater and future research prospective have been suggested.

Based on the discharge characteristics of agricultural non-point source pollution in the headstream region of the Kaihui River-a typical small agricultural watershed, an integrated ecological engineering treatment system (IEETS) was constructed with ecological wetland as the core unit to control the pollution. The nitrogen (N) and phosphorus (P) removal performances of the IEETS were discussed in this study. The results showed that the dominant source of N and P in the study area was livestock and poultry breeding, which was urgent to control. The monitoring results indicated that the ecological wetland treatment project resulted in average total nitrogen (TN) and total phosphorus (TP) removal rates of 87.1% and 90.9%, respectively, when treating mixed decentralized domestic and swine wastewater treatment. The multi-stage constructed wetlands had an average of 85.7% of TN and 84.9% of TP removal for mixed farmland drainage and decentralized swine wastewater. The removal rates for landscape-based ecological wetland were within the range of 27.1%-67.4% for TN and 13.3%-81.5% for TP in the catchment terminal water. The total interception amount of TN and TP by the IEETS was 5292 kg·a-1 and 1054 kg·a-1, accounting for 35.3% and 43.6% of total pollution loads in the headstream region, respectively. These findings illustrated that the IEETS presents promising treatment results on non-point source pollution, and is suitable for widespread applications to wastewater treatment in small watersheds of southern China.

A microporous porphyrin-based hydrogen-bonded organic framework, named PFC-5, was precisely designed and successfully constructed. Because of the present of multiple hydrogen bondings and π–π interactions between porphyrinic ligands, PFC-5 possesses a robust framework with excellent water, thermal, and chemical stability. A CO2 sorption isotherm demonstrated that PFC-5 possesses permanent microporosity after activation. The obtained material has been explored for highly selective C2 light hydrocarbons/CH4 separations at room temperature and normal pressure.

无奇迹论证作为科学实在论的主要论证包含了一个潜在的推理:如果一个理论做出了成功的预测,那么这足以说明该理论的真理性.然而,历史上无数的例子表明,基于理论的预测成功而被当作真理性的东西,在后来证明是错误的.为了应对这一历史性的挑战,实在论者对这一推理形式进行了诸多修改.目前有可能的辩护形式包括结构实在论的观点和强调证实的理论.但是结构实在论在一些关键的概念上还存在争议,同时由于是一种很强的选择性实在论立场而让许多实在论者难以接受.证实的方法虽然能够解决历史的反例带来的问题,但同时也带来了一些非历史的难题.

Pollutant concentrations in influents into constructed wetlands (CWs) are highly fluctuating and may vary over several orders of magnitude, leading to large uncertainties in removal performance assessment when using pollutant concentrations in the influent and effluent directly. Incorporating a probabilistic approach into removal performance assessment and needed area estimation of CWs could advantage decision making regarding wastewater treatment and engineering applications. A series of three-stage surface-flow CWs (SFCWs) were constructed for treating ammonium-rich swine wastewater. The surface removal rate and removal efficiency of ammonium nitrogen in the SFCWs using the probabilistic approach were 0.27-3.23 g m(-2) d(-1) and 43.0-99.9% (95% confidence interval (CI)), which were consistent with the deterministic approach (95% CI: 0.24-3.18 g m(-2) d(-1) and 70.4-99.9%). The needed SFCW area was estimated as 6.6 (95% CI: 1.4-17.8) to 29.7 (95% CI: 6.4-80.1) m(2) for required removal efficiency from 40% to 90% for 0.18 m(3) d(-1) swine wastewater with different strengthens. For specific removal efficiency of 90%, the needed CW areas was 13.9 (95%CI: 4.9-42.7), 25.1 (95% CI: 5.9-66.0), 33.5 (95%CI: 13.5-87.1), and 40.8 (95%CI: 16.2-89.4) m(2) for influent ammonium loading rate of 0.18-2.7, 2.7-14.4, 14.4-36, and 36-60 g d(-1), respectively. The first-order removal constant of ammonium nitrogen decreased logarithmically with increasing influent and effluent concentration/loading rate in the SFCW units (p < 0.001), which was responsible for the needed SFCW areas covering a wide range. The reliability analysis confirmed the results from the probabilistic approach were appropriate. The present study shed new lights on the performance evaluation and design of CWs for treating wastewater with highly-fluctuating concentrations using a probabilistic approach.

Controlled growth of ZnS/ZnO heterojunctions on porous biomass carbons has been achieved via a one-step carbothermal reduction strategy.

Exploring optimal C:N ratio is necessary to ensure balanced microbial nitrification and denitrification in constructed wetlands (CWs), which has become an important management practice for more efficient nitrogen removal and sustainability of CWs. Surface flow constructed wetlands (SFCWs) vegetated with Myriophyllum aquaticum were designed to investigate the effects of five different influent C:N ratios (0:1, 2.5:1, 5:1, 10:1, and 15:1) on nitrogen removal performance and microbial communities over a 175-day experimental period. Compared to the influent C:N ratios of 0:1, higher NH4+-N, NO3--N, and total nitrogen (TN) removal efficiencies and lower NO3--N accumulation were observed at influent C:N ratios higher than 5:1. In addition, the highest TN removal efficiency (70.4%) and the lowest nitrous oxide emission flux (4.12 mg m(-2) d(-1)) were obtained at the influent C:N ratio of 5:1. High-throughput sequencing revealed that influent C:N ratios altered the distribution and composition of microbial communities in the sediment, which resulted in a dynamic interplay between N-transforming functional microbes and NH4+-N and NO3--N removal. In particular, the dominant denitrifiers, including Desulfovibrio, Zoogloea, and Dechloromonas, weremore abundant in the sediment with an influent C:N ratio of 5:1, which contributed to the high N removal rate. These findings may be used to screen for an optimum influent C:N ratio to maintain the sustainability of SFCWs with higher N removal efficiency. (C) 2019 Published by Elsevier B.V.

By introducing a coordinative phosphate group into a carboxylic acid linker, a ligand was successfully synthesized and used to construct phonocarboxylate framework with narrow approachable channels.

This study investigated nitrogen (N) removal process and microbial community distribution in a full-scale integrated constructed wetland (ICW), which was constructed with a bioreactor (R) and three wetland units (W1, W2, and W3) arranged successively along the flow path. For swine wastewater treatment, ICW showed high N removal efficiency with average removal rate of 98% for NH4+-N and 96% for total nitrogen (TN) from August 2012 to July 2014. In ICW sediments, abundance of amoA gene of ammonia-oxidizing archaea (AOA) was 1 order of magnitude greater than ammonia-oxidizing oxidizing bacteria (AOB), and narG gene was 2 orders of magnitude greater than nosZ. The highest amoA gene abundance of AOA and AOB in R were consistent with the most efficient NH4+-N and TN removal compared to W1, W2, and W3. Both W1 and W3 vegetated with Myriophyllum aquaticum had significantly higher AOA abundance than W2 vegetated with Ipomoea aquatica, Zizania latifolia, and Nasturtium officinale (p < 0.05). Responding to the increasing NO3--N concentrations along the flow path, higher narG and nosZ abundance were observed in W2 and W3 than in R and W1. Principal component analysis revealed that there were clear differences in the relative abundance of terminal restriction fragments. These findings demonstrated that environmental factors such as wetland plants and NH4+-N and NO3--N concentrations had effects on the distri bution of microbial ammonia oxidizers and denitrifiers. Therefore, the responsible development of functional microbial communities could contribute to efficient N removal in the ICW. (C) 2017 Elsevier B.V. All rights reserved.

Anisotropic Pd nanoparticles with highly branched morphologies are urgently needed as building blocks for nanoscale devices, catalysts, and sensing materials owing to their novel structures and unique physicochemical properties. However, realizing size control and branch manipulation for these materials is very challenging. In this study, we develop a facile ultrafine Cu seed-mediated approach in the aqueous phase to produce novel Pd–Cu trigonal hierarchical nanoframes (THNFs). The main branch of most of the obtained nanocrystals is tripod-like, with advanced branches along the arms as frame units having self-similarity. In this method, the size of the Pd–Cu THNFs can be flexibly controlled by manipulating the nucleation involving the sub-3 nm Cu seeds. These Pd–Cu THNFs outperform Pd black with regard to their ethanol-oxidation performance, having a specific activity and mass activity 9.7 and 6.6 times higher, respectively. This research provides a versatile ultrafine seed-mediated approach for producing size-controlled anisotropic bimetallic nanoframes.

信息计算主义以信息和计算为基础来理解物理世界和整个宇宙.根据这种观点,物理宇宙是在信息结构上进行计算的计算过程网络.信息作为结构组织着整个宇宙,物理宇宙的动力学就是在做自然运算.信息计算主义哲学观的产生离不开信息科学技术的发展.在全球知识生产的复杂网络中,在交叉学科研究中表达出的全球化、信息网络、多元主义和多样化是需要在高度的抽象水平上表达的现象,这需要哲学论述来提供.但是,信息计算主义决不是宇宙万物的最终答案.作为一个学习的工具,它可能有助于我们在信息计算这个特殊的抽象层面上加强不同研究领域、知识共同体和信息源之间的交流,建立新的知识统一框架.

Three sandwich-type inorganic–organic hybrid solids based on iso-polyvanadate cluster, {V4O12}4–, {H2V6O18}4–, or {H2V10O28}4–, and decamethylcucurbit[5]uril (Me10CB[5]) have been synthesized under hydrothermal conditions. In the structures of (NH4)4[(V4O12)·(Me10CB[5]@0.5H2O)2]·∼15H2O (1) and (NH4)4[(H2V10O28)·(Me10CB[5]@H2O)2]·∼16H2O (3), tetranuclear {V4O12}4– or decanuclear {H2V10O28}4– clusters are sandwiched by (NH4)2@Me10CB[5] closed molecular capsules, through hydrogen-bonding interactions, whereas compound 2, formulated as Li4(H2O)6[(H2V6O18)·(Me10CB[5]@H2O)2]·∼14H2O, is built by hexanuclear {H2V6O18}4– clusters that are covalently sandwiched by Li2@Me10CB[5] half-open molecular capsules in a way similar to thoset of 1 and 3. Compounds 1–3 represent rare examples of sandwich-type polyoxometalate (POM)-based materials in which POM units are inserted at the inner sphere by either hydrogen or covalent bonds. Compound 2 has shown rational photocatalytic activity toward the degradation of methyl orang...

A 3D water-stable anionic metal-organic framework [Zn4(hpdia)2]·[NH2(CH3)2]·3DMF·4H2O (FJI-C4) was constructed based on an elaborate phosphorus-containing ligand 5,5'-(hydroxyphosphoryl)diisophthalic acid (H5hpdia). FJI-C4 with narrow one-dimensional (1D) pore channels exhibits high selectivity of C3H8/CH4 and C2H2/CH4. It is the first time for the MOF which contains phosphorus for selective separation of methane from natural gas and pyrolysis gas.

Constructed wetlands are increasingly used to control nitrogen (N) pollution diffusion from agricultural source to downstream water. In order to compare N removal efficiencies for swine wastewater treatment, three wetland microcosms vegetated with Myriophyllum aquaticum (Myriophyllum), Alternanthera philoxeroides (Alternanthera), or without vegetation (Control) were constructed in an agricultural area of southern China. Meanwhile, the key environmental factor and N removal pathway were investigated among the three microcosms. The results showed that, after 30 days incubation, 96.4% of TN was removed in Myriophyllum microcosm, significantly higher than 74.2% and 47.3% in Alternanthera and Control microcosms (p < 0.05). Plant N accumulation was significantly higher in M. aquaticum than A. philoxeroides (p <0.05). The analysis of Pearson's correlation revealed that the NH4+-N concentrations were negatively correlated with DO concentrations and Eh values. Microbial nitrification-denitrification was the dominant N removal pathway in the three microcosms, accounting for 66.9-80.5% of the TN removal. Furthermore, NH3 volatilization in Control was significantly higher than those in Myriophyllum and Alternanthera microcosms (p < 0.05). These findings suggested that plant vegetation in constructed wetlands (e.g., M. aquaticum) improved N removal efficiency in treating swine wastewater and additionally reduced NH3 volatilization. (C) 2016 Elsevier B.V. All rights reserved.

本研究以绿狐尾藻(Myrioph yllum elatinoides)湿地系统为对象,分析绿狐尾藻湿地系统中NH4+-N的去除规律及氮质量平衡.结果表明,试验第28天,在200和400 mg·L-1 NH4+-N两个处理中,水体全氮(TN)去除率分别为86.1％和77.7％,NH4 +-N去除率分别为89.8％和78.8％.根据氮质量平衡得出,在200和400 mg·L-1 NH4 +-N两个处理中分别有14.7％和30.2％的外源NH4+-N直接被底泥吸附,25.3％和l1.0％转化成底泥NO3-N,29.7％和12.7％被绿狐尾藻直接吸收利用,14.o％和23.3％残留在水体,剩余16.3％和22.8％可能被微生物硝化反硝化作用去除.研究结果表明,绿狐尾藻对氨氮有较好的净化效果,为其在人工湿地的应用提供了科学依据.