1. 题目: Treatment of iodine-containing water by the UV/NH2Cl process: Dissolved organic matters transformation, iodinated trihalomethanes formation and toxicity variation
期刊: Water Research
作者: Jing Wang, Jie Zhang, Shi-Qi Huang, Yi Hu, Yang Mu
摘要: UV/NH2Cl process is becoming increasingly important for water treatment, while its impact on iodine-containing water remains unknown. In this study, the structure transformation of dissolved organic matters (DOMs), generation of iodinated trihalomethanes (I-THMs), and variation of acute toxicity were evaulated during the UV/NH2Cl treatment of iodine-containing water. The combination of exciation emission matrix-parallel factor analysis and two-dimensional correlation spectroscopy integrated with synchronous fluorescence and infrared absorption spectroscopy showed that fulvic-like fraction of DOM was more susceptible to UV/NH2Cl process and particularly iodo and polysaccharide groups gave the fastest resopnses. Cosequnently, UV fluence lower than 60 mJ/cm2 promoted the production of I-THMs, while excessive UV exhausted NH2Cl and reactive iodine species and subsequently reduced I-THMs generation. Moreover, DOM concentration and source, NH2Cl dosage, and I− concentration had significant impacts on I-THM formation in the UV/NH2Cl process. Additionally, a positive correlation was found between acute toxicity variation and I-THM formation when treating iodine-containing waters with UV/NH2Cl. These results together provide a comprehensive understanding on UV/NH2Cl treatment of iodine-containing water.
2. 题目: Deep-water inflow event increases sedimentary phosphorus release on a multi-year scale
作者: Astrid Hylén, Sebastiaan J. van de Velde, Mikhail Kononets, Mingyue Luo, Elin Almroth-Rosell, Per O. J. Hall
摘要: Phosphorus fertilisation (eutrophication) is expanding oxygen depletion in coastal systems worldwide. Under low-oxygen bottom water conditions, phosphorus release from the sediment is elevated, which further stimulates primary production. It is commonly assumed that re-oxygenation could break this “vicious cycle” by increasing the sedimentary phosphorus retention. Recently, a deep-water inflow into the Baltic Sea created a natural in situ experiment that allowed us to investigate if temporary re-oxygenation stimulates sedimentary retention of dissolved inorganic phosphorus (DIP). Surprisingly, during this 3-year study, we observed a transient but considerable increase, rather than a decrease, in the sediment efflux of DIP and other dissolved biogenic compounds. This suggested that the oxygenated inflow elevated the organic matter degradation in the sediment, likely due to an increase in organic matter supply to the deeper basins, potentially combined with a transient stimulation of the mineralisation efficiency. As a result, the net sedimentary DIP release per m2 was 56 %–112 % higher over the years following the re-oxygenation than before. In contrast to previous assumptions, our results show that inflows of oxygenated water to anoxic bottom waters can increase the sedimentary phosphorus release.
3. 题目: Concentration distribution, enrichment and controlling factors of metals in Al-Shuaiba Lagoon sediments, Eastern Red Sea, Saudi Arabia
期刊: Environmental Earth Sciences
作者: Ramadan H. Abu-Zied, Bandar A. Al-Mur, Mohammed I. Orif, Ahmed Al Otaibi, Mohammed A. Ghandourah
摘要: Fifty surficial bottom sediments from the Al-Shuaiba Lagoon (80 km south of Jeddah City, eastern Red Sea, Saudi Arabia) were investigated for some major and trace metals to map their concentration distribution in the lagoon, shed light on their origin and controlling factors, and to establish potential risks to living organisms through comparison with sediment quality guidelines (SQGs). Statistical analyses allowed the division of metals into five associations: (1) Mg-Ca-Sr, (2) Al-Zn-Cr-Ni-Cu, (3) Fe–Mn-Li, (4) K and (4) Pb–Cd. Their distributions indicated that elevated values of Al, Mg, Fe, Sr, K, Mn, Li, Zn, Cr, Cu, Pb, Ni and Cd occurred in high intertidal areas and in mangrove sediments. These decreased gradually towards the deeper waters and inlet, except for Ca, which had its highest concentration in the centre of the lagoon. Major elements mainly appear to originate from the mineralization and evaporation of the lagoon’s water, whereas trace elements appear to originate from wind-blown dust and runoff, with subsequent concentration in sediments aided by adsorption onto fine particles and organic carbon complexes. Enrichment indices and a pollution load index (PLI) indicated that the lagoon sediments were highly enriched with Sr, Pb and Cd, with the latter two and PLI being the highest at the eastern side of the lagoon. Comparison with the SQGs showed that the concentrations of Cu, Pb and Cd are higher than the effect range low (ERL) and threshold effect level (TEL), but are lower than the effect range median (ERM). This suggests that these metals might cause an occasional threat to the biota in the eastern part of the lagoon.
4. 题目: Heterogeneous catalytic ozonation of sulfamethazine in aqueous solution using maghemite-supported manganese oxides
期刊: Separation and Purification Technology
作者: Xinghao Liu, Haipu Li, Ying Fang, Zhaoguang Yang
摘要: Sulfamethazine (SMT), widely used for treating diseases by bacterial infections, is difficult to degrade with the traditional water treatment process completely. Catalytic ozonation with synthesized maghemite-supported manganese oxides (MnxOy/γ-Fe2O3) as the catalyst could degrade 100% SMT in 30 min and remove 61.9% TOC in 90 min. Moreover, the TOC removal ratio was 1.79 times higher than that with ozonation alone. The SMT mineralization increased with increasing the ozone dosage, catalyst dosage, and pH of the solution, but it decreased with increasing the SMT concentration. Furthermore, the generated hydroxyl radical contributed to SMT mineralization. The -OH on the surface of MnxOy/γ-Fe2O3 could further react with O3 to trigger a series of reactions and generate the reactive species. The polyvalent manganese provided the electrons for O3 to produce the reactive species. The degradation process of SMT mainly consisted of de-sulfuration and hydroxylation. The toxicity of final intermediates was negligible compared with that of SMT. The anions or the humic acid in the solution could affect SMT mineralization. The excellent catalytic activity, reusability, and stability of MnxOy/γ-Fe2O3 catalysts lay a good foundation for practical application in the future.
5. 题目: Terrestrial dissolved organic matter inflow drives temporal dynamics of the bacterial community of a subarctic estuary (northern Baltic Sea)
期刊: Environmental Microbiology
作者: D. Figueroa, E. Capo, M.V. Lindh, O.F. Rowe, J. Paczkowska, J. Pinhassi, A. Andersson
摘要: Climate change is projected to cause increased inflow of terrestrial dissolved organic matter to coastal areas in northerly regions. Estuarine bacterial community will thereby receive larger loads of organic matter and inorganic nutrients available for microbial metabolism. The composition of the bacterial community and its ecological functions may thus be affected. We studied the responses of bacterial communities to inflow of terrestrial dissolved organic matter in a subarctic estuary in the northern Baltic Sea, using a 16S rRNA gene metabarcoding approach. Betaproteobacteria dominated during the spring river flush, constituting ~60% of the bacterial community. Bacterial diversity increased as the runoff decreased during summer, when Verrucomicrobia, Betaproteobacteria, Bacteroidetes, Gammaproteobacteria and Planctomycetes dominated the community. Network analysis revealed that a larger number of associations between bacterial populations occurred during the summer than in spring. Betaproteobacteria and Bacteroidetes populations appeared to display similar correlations to environmental factors. In spring, freshly discharged organic matter favoured specialists, while in summer a mix of autochthonous and terrestrial organic matter promoted the development of generalists. Our study indicates that increased inflows of terrestrial organic matter‐loaded freshwater to coastal areas would promote specialist bacteria, which in turn might enhance the transformation of terrestrial organic matter in estuarine environments.
6. 题目: Determination of Instinct Components of Biomass on the Generation of Persistent Free Radicals (PFRs) as Critical Redox Sites in Pyrogenic Chars for Persulfate Activation
期刊: Environmental Science & Technology
作者: Wei Wu, Shishu Zhu, Xiaochen Huang, Wei Wei, Chao Jin, Bing-Jie Ni
摘要: Persulfate (PS) activation on biochar (BC) is a promising technology for degrading the aqueous organic contaminants. However, the complexity of activation mechanisms and components in biomass that used to produce BC makes it difficult to predict the performance of PS activation. In this study, we employed eight sludges as the representative biomass that contained absolutely different organic or inorganic components. Results showed that the elemental composition, surface properties, and structures of the sludge-derived BCs (SBCs) clearly depended on the inherent components in the sludges. The intensities of persistent free radicals (PFRs) in the electron paramagnetic resonance (EPR) correlated positively with N-containing content of sludges as electron shuttle, but negatively with the metal content as electron acceptor. Linking with PFRs as crucial sites of triggering a radical reaction, a poly-parameter relationship of predicting PS activation for organic degradation using the sludge components was established (kobs,PN = 0.004 × Cprotein + 0.16 × CM–0.895 −0.118). However, for the PS activation on those SBCs without PFRs, this redox process only relied on the sorption or conductivity-related characteristics, not correlating with the content of intrinsic components in biomass but with pyrolysis temperatures. This study provided insightful information of predicting the remediation efficiency of PS activation on BCs and further understanding the fate of contaminants and stoichiometric efficiency of oxidants in a field application.
7. 题目: Discovering the potential of an nZVI-biochar composite as a material for the nanobioremediation of chlorinated solvents in groundwater: Degradation efficiency and effect on resident microorganisms
作者: Jaroslav Semerád, Alena Ševců, Nhung H.A. Nguyen, Pavel Hrabák, Roman Špánek, Kateřina Bobčíková, Kristýna Pospíšková, Jan Filip, Ivo Medřík, Josef Kašlík, Ivo Šafařík, Alena Filipová, Jaroslav Nosek, Martin Pivokonský, Tomáš Cajthaml
摘要: Abiotic and biotic remediation of chlorinated ethenes (CEs) in groundwater from a real contaminated site was studied using biochar-based composites containing nanoscale zero-valent iron (nZVI/BC) and natural resident microbes/specific CE degraders supported by a whey addition. The material represented by the biochar matrix decorated by isolated iron nanoparticles or their aggregates, along with the added whey, was capable of a stepwise dechlorination of CEs. The tested materials (nZVI/BC and BC) were able to decrease the original TCE concentration by 99% in 30 days. Nevertheless, regarding the transformation products, it was clear that biotic as well as abiotic transformation mechanisms were involved in the transformation process when nonchlorinated volatiles (i.e., methane, ethane, ethene, and acetylene) were detected after the application of nZVI/BC and nZVI/BC with whey. The whey addition caused a massive increase in bacterial biomass in the groundwater samples (monitored by 16S rRNA sequencing and qPCR) that corresponded with the transformation of trichloro- and dichloro-CEs, and this process was accompanied by the formation of less chlorinated products. Moreover, the biostimulation step also eliminated the adverse effect caused by nZVI/BC (decrease in microbial biomass after nZVI/BC addition). The nZVI/BC material or its aging products, and probably together with vinyl chloride-respiring bacteria, were able to continue the further reductive dechlorination of dichlorinated CEs into nonhalogenated volatiles. Overall, the results of the present study demonstrate the potential, feasibility, and environmental safety of this nanobioremediation approach.
8. 题目: Effects of dissolved oxygen on the sludge dewaterability and extracellular polymeric substances distribution by bioleaching
作者: Yun bei LI, Jun li SONG, Qian jing YAO, Ze xu CHEN, Yi WEI, Hai long LI, Meng xiao WANG, Bing jing WANG, Jia min ZHOU
摘要: Bioleaching is a biological conditioning technology for sludge, which not only improves sludge dewatering performance but also removes heavy metals from sludge. As the bioleaching process is a comprehensive biological and chemical process, it is necessary to explore the effects of dissolved oxygen (DO) concentrations on bioleaching efficiency. Three bioleaching experiments with different DO concentrations (T1: 0.8–3.1 mg/L, T2: 3.1–5.5 mg/L, T3: 5.5–7.5 mg/L) were conducted for five days. The sludge dewatering efficiency was evaluated using capillary suction time (CST) and specific resistance to filtration (SRF). The relationship between sludge dewaterability and extracellular polymeric substance (EPS) fraction distribution was investigated. In the treatment with the highest DO concentration, the minimum values of SRF and CST were 4.31 ×1011 m/kg and 13.5 s, which occurred earlier than the treatment with the lower DO concentrations by approximately 24–48 h. A significant decrease (83.4–93.2%) in tightly bound EPS (TB-EPS) protein (PN) was observed in all treatments, while a positive correlation (r = 0.924, P < 0.01) was observed between SRF and PN content in TB-EPS. A relatively higher abundance of Acidithiobacillus was found with the increase in DO concentration. Additionally, other genera including Metallibacterium, Alicyclobacillus, Acidibacter, Acidocella, and Luteococcus also played important roles in EPS biodegradation. These results revealed that increasing the DO concentration could improve sludge dewatering performance and heavy metal removal by enhancing bioleaching microbial activity, the degradation of PN in TB-EPS, and sludge floc fragmentation, but only if sufficient energy sources were provided.
9. 题目: Disentangling the effects of OM quality and soil texture on microbially mediated structure formation in artificial model soils
作者: Franziska B. Bucka, Vincent J.M.N.L. Felde, Stephan Peth, Ingrid Kögel-Knabner
摘要: The interaction between mineral particles and soil organic matter (SOM) is an important and complex process during soil structure formation, in which the effects of soil texture and OM properties are intertwined. Within the SOM, there are residues of particulate organic matter (POM) of various sizes, as well as microbial necromass co-existing. These OM residues undergo microbial decay whose products stabilize particle connections and thus induce aggregate formation. We developed an experimental set-up to study early soil structure formation within a controlled lab environment. Artificial soil microcosms with a mineral mixture of different textures (clay loam, loam, and sandy loam) were used to perform a short-term incubation for 30 days under constant water tension. OM was added individually either as POM of two different size classes (milled hay litter, 0.63–2 mm and <63 µm, respectively) or bacterial necromass (Bacillus subtilis). The dry mixing process and incubation of the mineral mixtures led to particle–particle interactions and fine particle coatings of the sand grains as shown by a reduction in the specific surface area (N2-BET). The OM residues were quickly accessed and degraded by microbes (peak in CO2-release within the first 10 days of incubation), which induced the formation of water-stable aggregates. The POM of both sizes induced predominantly the formation of macroaggregates (0.63–30 mm) with a mass contribution of 72% to 91%, irrespective of the mixtures’ texture. The bacterial necromass induced a texture-dependent formation of macro- and microaggregates (63–200 µm), with larger aggregates in sand-rich mixtures. The different aggregate sizes were related to differences in the developed microbial community, as obtained by PLFA analysis. The bacterial necromass induced a microbial community dominated by bacteria, whereas the POM fostered a high relative abundance of fungi, whose hyphae could enmesh and stabilize large aggregates in all textures. The formed aggregates are water-stable but have a very low mechanical stability. Dry crushing with a mechanical loading frame revealed that very low forces (<4 N) were sufficient for breaking the aggregates down. Microbial growth and degradation of the OM residues led to OM patches occupying <17% of the mineral surfaces after the incubation, suggesting that the aggregates are loosely connected structures, bound together by some distinct spots of processed OM acting as gluing joints. This initially formed scaffold holds particles in place for further stabilization processes and resists immersion in water but exhibits no stability toward mechanical forces.
10. 题目: A critical review on the application and recent developments of post-modified biochar in supercapacitors
期刊: Journal of Cleaner Production
作者: Xiangping Li, Jianguang Zhang, Bin Liu, Zhenping Su
摘要: The demand for sustainable and renewable energy sources has gained tremendous research attention around the world over the past years. Supercapacitor, among lots of energy storage devices, has been attracted many researches for the advantages of high power density, fast charge-discharge capability and cycle stability. Compared with other carbon materials, biochar materials have attracted special attention as efficient, low-cost, active materials for energy storage. In this work, the typical preparation and modification methods of biochar as the supercapacitor electrode are classified. the factors influencing the electrochemical performance of biochar, such as specific surface area (SSA), pore structure, surface chemical modification and conductivity are systematically discussed. This work studied the relationship between carbon with mesopore and hierarchical pore structure and the electrochemical performance of biochar electrode materials. The advantages and disadvantages of introducing heteroatoms and functional materials on the surface of biochar for supercapacitor electrode are analyzed. Meanwhile, future development trends for biochar materials in this field are also prospected.
11. 题目: Deciphering microbial mechanism underlying soil organic carbon storage in a wheat maize rotation system
期刊: Science of The Total Environment
作者: Xinjie Wu, Pengfei Liu, Carl-Eric Wegner, Yu Luo, Ke-Qing Xiao, Zhenling Cui, Fusuo Zhang, Werner Liesack, Jingjing Peng
摘要: A link between microbial life history and soil organic carbon storage in agroecosystems is presumed, but largely unexplored at the gene level. We aimed to elucidate whether and how differential organic material amendments (manure versus peat-vermiculite) affect, relative to a sole chemical fertilizer treatment, the link between microbial life history and soil organic carbon storage in a wheat-maize rotation field experiment. To achieve this goal, we combined bacterial 16S rRNA gene and fungal ITS amplicon sequencing, metagenomics and the assembly of genomes. Fertilizer treatments had a significantly greater effect on microbial community composition than aggregate size, with soil available phosphorus and potassium being the most important community-shaping factors. Limitation in labile carbon was linked to a K-selected oligotrophic life history (Gemmatimonadetes, Acidobacteria) under a sole chemical fertilizer treatment; defined by a significant enrichment of genes involved in resource acquisition, glycosyl hydrolases, and in competition. By contrast, excess of labile carbon promoted an r-selected copiotrophic life history (Cytophagales, Bacillales, Mortierellomycota) under manure treatment; defined by a significant enrichment of genes involved in cellular growth. A distinct life-history strategy was not observed under peat-vermiculite treatment, but rather a mix of both K-selected (Acidobacteria) and r-selected (Actinobacteria, Mortierellomycota) microorganisms. Compared to a sole chemical fertilizer treatment, soil organic carbon storage efficiency was significantly increased by 26.5% and 50.0% under manure and peat-vermiculite treatments, respectively. Taken together, our results highlight the importance of organic material amendments, but in particular a one-time peat-vermiculite application, to promote soil organic carbon storage as a potential management strategy for sustainable agriculture.
12. 题目: Adsorption behaviors of paper mill sludge biochar to remove Cu, Zn and As in wastewater
期刊: Environmental Technology & Innovation
作者: Zhiyong Xu, Yunqin Lin, Yuejin Lin, De Yang, Haomin Zheng
摘要: Paper mill sludge biochar (PMSB) was produced via pyrolysis in a muffle furnace at 750 °C. Subsequently, PMSB was soaked in the HCl solution and washed by deionized water to obtain minerals and organic materials. The organics were named as demineralized paper mill sludge biochar (DPMSB). It was found that PMSB and minerals had larger pore diameters than DPMSB. Also, the removal efficiencies of Cu, Zn and As were above 95.00% by using PMSB and minerals because of the large pores, abundant carbonates and -OH groups, while the removal efficiencies of Cu, Zn and As by using DPMSB were 40.92%, 87.93% and 94.99%, respectively, owing to the H+ competition to Cu and Zn adsorption but more micropores to enhance As adsorption. The adsorption behavior of PMSB showed that the adsorption isotherms of Cu, Zn and As could be well simulated by the Freundlich model, and the pseudo-second-order model fitted the adsorption kinetics of Zn and As, and the Elovich model fitted the adsorption kinetics of Cu. Moreover, the optimal dosages of PMSB to adsorb Cu, Zn and As were 0.3, 0.3 and 0.1 g/L, respectively. And the pH values of the solution for the efficient adsorption of Cu, Zn and As were 4.00, 6.00 and 2.00, respectively. This work provided basic data for the potential commercial application of PMSB for heavy metals removal from wastewater.
13. 题目: A novel eco-friendly recycling of food waste for preparing biofilm-attached biochar to remove Cd2+ and Pb2+ in wastewater
期刊: Journal of Cleaner Production
作者: Yonghui Xing, Xuesong Luo, Song Liu, Wenjie Wan, Qiaoyun Huang, Wenli Chen
摘要: The development of green and sustainable cleaning technologies to properly reuse food waste and remove heavy metals in wastewater can avoid secondary damage to the environment. Our study proposes an innovative way to prepare an efficient adsorbent by growing biofilm bacteria in food waste and attaching them to biochar also prepared from food waste. Modification of the biochar by bacterial biofilm reduced the specific surface area but increased the average pore and the adsorption performance of Cd2+ and Pb2+. Electrostatic adsorption and the complexation by oxygen-containing functional groups were the main adsorption mechanisms of biofilm-attached biochar, and it was also easily recyclable by re-growth of the biofilm cultured by food waste. In wastewater containing both Cd2+ and Pb2+, the two have competitive adsorption sites on biofilm-attached biochar, but more functional groups participate in removing Cd2+. This study proposes a new idea to reuse food waste and prepare bio-modified biochar adsorbents and provides a strategy to remove Cd2+ and Pb2+ in wastewater by applying biofilm-attached biochar.
14. 题目: Enhanced bioremediation of 2,3’,4,4’,5-pentachlorodiphenyl by consortium GYB1 immobilized on sodium alginate-biochar
期刊: Science of The Total Environment
作者: Xiaofang Ouyang, Hua Yin, Xiaolong Yu, Zhanyu Guo, Minghan Zhu, Guining Lu, Zhi Dang
摘要: 2,3’,4,4’,5-pentachlorodiphenyl (PCB 118), a dioxin-like PCB, is often detected in the environment and is difficult to be aerobically biodegraded. In this study, a novel polychlorinated biphenyl degrading consortium GYB1 that can metabolize PCB 118 was successfully obtained by acclimatization process. To enhance the application performance of free bacterial cells, consortium GYB1 was immobilized with sodium alginate and biochar to prepare SC-GYB1 beads. Orthogonal experiments indicated that the optimal composition of the beads (0.2 g) was 2.0% sodium alginate (SA) content, 2.0% wet weight of cells and 1.5% biochar content, which can degrade 50.50% PCB 118 in 5 d. Immobilization shortened the degradation half-life of 1 mg/L PCB 118 by consortium GYB1 from 8.14 d to 3.79 d and made the beads more robust to respond to environmental stress. The SC-GYB1 beads could even keep considerable PCB degradation ability under 200 mg/L Cd2+ stress. According to 16S rRNA gene analysis, Pseudomonas and Stenotrophomonas played the dominant role in consortium GYB1. And embedding obviously altered the community structure and the key bacterial genera during the PCB removal process. Therefore, the immobilization of bacteria consortium by sodium alginate-biochar enhanced the biodegradation of PCB 118, which will provide new insights into functional microorganisms' actual application for PCB restoration.
15. 题目: Lipids and their δ13C values reveal carbon assimilation and cycling in the methane-seep tubeworm Paraescarpia echinospica from the South China Sea
期刊: Deep Sea Research Part I: Oceanographic Research Papers
作者: Hongxiang Guan, Daniel Birgel, Dong Feng, Jörn Peckmann, Lei Liu, Lihua Liu, Jun Tao
摘要: Gutless tubeworms obtain their nutrition from their bacterial endosymbiotic partners, and the metazoan hosts provide the bacteria with sulfide, carbon dioxide, and molecular oxygen taken up through the plume. At seeps, tubeworms take up sulfide using their posterior end, allowing them to fix carbon dioxide and synthesize organic molecules. Compared to bulk tissue isotope compositions, lipid biomarkers and their compound-specific δ13C values of soft tissues allow to assign nutritional modes of endosymbionts and hosts, as well as associations between endosymbionts and the animal host. In this study, the tubeworm Paraescarpia echinospica retrieved from the Haima seeps in the South China Sea (SCS) at approximately 1400 m water depth was analyzed using 16S rRNA, bulk tissue isotopes, lipid biomarkers, and compound-specific δ13C values. The Lamellibrachia sp. endosymbiont, a phylotype of the Gammaproteobacteria, is a bacterium gaining energy from oxidizing sulfur compounds (thiotrophic endosymbiont). Further, six phylotypes of Gammaproteobacteria and seven phylotypes of Alphaproteobacteria were identified in the trophosome. High contents of n-C16:1ω7, n-C18:1ω7 fatty acids, and n-C16:0 and n-C18:1ω7 fatty alcohols were found in the trophosome, and somewhat lower contents in the plume and vestimentum, consistent with the prevalence of thiotrophic endosymbionts in the trophosome. The fatty acids n-C16:1ω7 and n-C18:1ω7 produced by the endosymbionts yielded δ13C values ranging from −34‰ to −30‰, reflecting the use of marine dissolved inorganic carbon (DIC) rather than DIC derived from anaerobic oxidation of methane. The overall small differences in δ13C values (Δamong tissues ≤3‰) for n-C16:1ω7 and n-C18:1ω7 fatty acids in both symbiont-containing and symbiont-free tissues appear to represent the δ13C signatures of the endosymbionts. Generally, n-C16:1ω7 and n-C18:1ω7 fatty acids should be more 13C-depleted than the respective n-C16:0, n-C18:0 fatty acids resulting from desaturation. However, in this study, the saturated n-C16:0, n-C18:0 fatty acids in soft tissues were 13C depleted by 4‰–10‰ compared to the respective n-C16:1ω7 and n-C18:1ω7 fatty acids, suggesting complex trophic interactions between P. echinospica, its endosymbionts, other bacteria living in P. echinospica, and the environment. Sterols, yielding the lowest δ13C values from −49‰ to −46‰, are interpreted to be derived from bioconversion of dietary sterols by the animal host. The combination of microbial diversity, bulk tissue isotopes, and lipid biomarkers used here is a valuable approach to evaluate the nutritional associations between symbionts and hosts in chemosymbiosis as well as the diet of the animal host.
16. 题目: Mixture of controlled-release and conventional urea fertilizer application changed soil aggregate stability, soil humic acid molecular composition, and nitrogen uptake
期刊: Science of The Total Environment
作者: Yongxiang Gao, Xue Song, Kexin Liu, Taige Li, Wenkui Zheng, Yong Wang, Zhiguang Liu, Min Zhang, Qi Chen, Zeli Li, Ruochen Li, Lei Zheng, Wenlong Liu, Tianyu Miao
摘要: Controlled-release urea (CRU) fertilizer application has been shown to improve crop yield and nitrogen (N) use efficiency. However, its effects when mixed with conventional urea fertilizer on soil aggregate stability, humic acid (HA) molecular composition and crop N uptake remain unclear. Soil and plant samples were collected from a long-term (2008-2019) experiment on field maize (Zea mays L., ‘Zhengdan 958’) which included two types of fertilizers [conventional urea fertilizer (CUF), blended CUF with CRU fertilizer (CRF)], four N application rates (0, 150, 300 and 450 kg ha-1), each in three replicates. The results showed that at 300 kg N ha-1, compared to CUF treatment, the CRF treatment significantly improved soil aggregate characteristics [aggregate content with particle size larger than 0.25 mm (R0.25) by 9.6%, mean weight diameter by 19.8%, and geometric mean diameter by 21.7%]. CRF treatment also increased HA content by 5.5%, fulvic acid (FA) by 5.5%, lignin-like molecules by 0.94 times, and protein-like molecules by 3.69 times. At grain-filling stage, CRF treatments significantly increased the sum of soil NH4+-N and NO3--N content by 23.3-24.5%, sap bleeding rate by 12.8-18.2% and N delivery rate through bleeding sap by 60.6-87.7% compared to CUF treatments at the same N application rate. At the same rate of N application, the CRF treatments significantly improved the average yield during three growing seasons by 9.4-14.0% in contrast with CUF treatments. The regression equations showed that the maximum yield was 8,294 kg ha-1 for CUF at the application rate of 312 kg N ha-1 while it was 9,890 kg ha−1 for CRF at the application rate of 286 kg N ha−1. We conclude that the long-term application of CRF changed the HA molecular structure, enhanced the water stable aggregates, improved crop N uptake, and increased economically viable maize yield.
17. 题目: Soil organic carbon in irrigated agricultural systems: a meta‐analysis
期刊: Global Change Biology
作者: David Emde, Kirsten Hannam, Ilka Most, Louise Nelson, Melanie Jones
摘要: Over the last 200 years, conversion of noncultivated land for agriculture has substantially reduced global soil organic carbon (SOC) stocks in upper soil layers. Nevertheless, practices such as no‐ or reduced tillage, application of organic soil amendments, and maintenance of continuous cover can increase SOC in agricultural fields. While these management practices have been well‐studied, the effects on SOC of cropping systems that incorporate irrigation are poorly understood. Given the large, and expanding, agricultural landbase under irrigation across the globe, this is a critical knowledge gap for climate change mitigation. We undertook a systematic literature review and subsequent meta‐analysis of data from studies that examined changes in SOC on irrigated agricultural sites through time. We investigated changes in SOC by climate (aridity), soil texture, and irrigation method with the following objectives: i) to examine the impact of irrigated agriculture on SOC storage, and ii) to identify the conditions under which irrigated agriculture is most likely to enhance SOC. Overall, irrigated agriculture increased SOC stocks by 5.9%, with little effect of study length (2 – 47 years). However, changes in SOC varied by climate and soil depth, with the greatest increase in SOC observed on irrigated semi‐arid sites at the 0 ‐ 10 cm depth (14.8%). Additionally, SOC increased in irrigated fine‐ and medium‐textured soils but not coarse‐textured soils. Furthermore, while there was no overall change to SOC in flood/furrow irrigated sites, SOC tended to increase in sprinkler irrigated sites, and decrease in drip irrigated sites, especially at depths below 10 cm. This work sheds light on the nuances of SOC change across irrigated agricultural systems, highlights the importance of studying SOC storage in deeper soils, and will help guide future research on the impacts of irrigated agriculture on SOC.
18. 题目: Ball-milled biochar incorporated polydopamine thin-film composite (PDA/TFC) membrane for high-flux separation of tetracyclic antibiotics from wastewater
期刊: Separation and Purification Technology
作者: Dawei Zhang, Kejing Zhang, Xiaolan Hu, Yingwen Xue, Lu Zhang, Yingxia Sun
摘要: Nowadays, attempts emerge in an endless stream to explore an efficient active interlayer to break the “trade-off” relationship between permeability and rejection of conventional thin-film composite (TFC) membrane. Biochar, which is often used as an economically efficient material in soil remediation and wastewater treatment, however, is usually neglected in the application of TFC membrane. This study fabricated a series of polydopamine (PDA)/TFC membranes incorporated with different concentrations of ball-milled biochar (BMBC) interlayer by the combination of conventional interfacial polymerization and bar coating method and employed them in antibiotics wastewater removal. Results indicated that water permeability of the optimized membrane (PDA/TFC-2) improved nearly two-fold (32±1.8 LMHB (L.m-2·h-1·bar-1) versus 18.6±1.6 LMHB for control membrane), and the rejection rates were also the highest (91.9% for chlortetracycline, 90.3% for tetracycline, 81.8% for Ciprofloxacin and 91.3% for oxytetracycline). Furthermore, the fouled PDA/TFC-2 membrane could be easily regenerated by NaOH washing and remained ∼70.6% permeability flux of that of fresh membrane even after five times washing, while the rejection rate was still more than 60%. The findings of our study not only provide a promising material for the separation of antibiotic wastewater but also give a new sight towards the application of biochar in wastewater treatment.
19. 题目: Degradation of cephalexin by persulfate activated with magnetic loofah biochar: performance and mechanism
期刊: Separation and Purification Technology
作者: Haocheng Song, Qiang Li, Yuxuan Ye, Fei Pan, Dajie Zhang, Dongsheng Xia
摘要: Antibiotic contamination has become a serious environmental problem and much attention has been paid to its purification. The sulfate radical (SO4•−) based advanced oxidation processes (AOPs) exhibited significant potential in the treatment of antibiotics. In this study, the magnetic biochar (Fe2O3@LBC) derived from loofah was prepared to activate persulfate (PS) for cephalexin (CEX) degradation. Under the optimal conditions, 73.9% of CEX was removed in the Fe2O3@LBC/PS system. Free radicals quenching experiments and electron paramagnetic resonance (EPR) analysis revealed that HO• and SO4•− were responsible for the degradation of CEX. The C-OH of the catalyst played a crucial role in the degradation process. In addition, the conversion between Fe3+ and Fe2+ enhanced the degradation of CEX by producing SO4•−. The degradation performance of other antibiotics and CEX in different water matrices indicated the broad adaptability and applications of Fe2O3@LBC. The main intermediates and the possible transformation pathways were proposed. These results provided a potential insight into biochar based catalysts for the degradation of antibiotics by activation of persulfate.
20. 题目: Phosphate alters the compositional characteristics of humic acid adsorbed onto goethite
期刊: Journal of Soils and Sediments
作者: ChunYan Luo, ShuaiLong Wen, ShiLin An, YueHan Lu, YingXun Du
摘要: Purpose The adsorption of organic matter and phosphate on minerals is a common natural process that has an important impact on the migration and burial of carbon and phosphorus. Previous studies have focused mainly on the influence of organic matter on the adsorption of phosphate. Yet, the influence of phosphate on the adsorption of different pools of organic matter is not well understood. This study evaluates changes in different organic matter pools during their adsorption to minerals in the presence of phosphate. Materials and methods Firstly, the adsorption behaviors of natural organic matter (i.e., humic acid) and phosphate on goethite were evaluated separately. Secondly, humic acid and phosphate were added to goethite at different orders to elucidate the effect of phosphate on the fractionation of humic acid components adsorbed to goethite. Results and discussion The results showed that when phosphate and humic acid were added simultaneously, goethite was preferentially combined with phosphate. In the absence of phosphate, SUVA254 of the humic acid solution decreased and E2/E3 of the solution increased during the adsorption. Among the six EEM-PARAFAC (excitation-emission matrix fluorescence coupled with parallel factor analysis) components of the humic acid, C1, C2, and C4 (terrestrial humus-like substances) decreased significantly and exhibited strong adsorption, C3 (microbial fulvic-like substance) showed weak adsorption, whereas C5 (photodegradation products) and C6 (tyrosine-like component) did not show evident adsorption. In the presence of phosphate, phosphate inhibited, and replaced the adsorbed C1, C2, and C4, but promoted the adsorption of C5, which increased the aromaticity and the molecular weight of the humic acid solution. Conclusions Our results reveal that phosphate influences the fractionation of humic acid components adsorbed onto goethite, suggesting that phosphate can alter the chemical composition of natural organic matter interacting with minerals and thus impact the burial and fractionation of natural organic matter at the mineral-water interface.