17441. 题目: Bioremediation of gaseous methyl tert-butyl ether by combination of sulfuric acid modified bagasse activated carbon-bone biochar beads and Acinetobacter indicus screened from petroleum contaminated soil
作者: Waleeporn Pongkua, Rujira Dolphen, Paitip Thiravetyan
摘要: Combination of sulfuric acid modified bagasse activated carbon-bone biochar beads and Acinetobacter indicus screened from petroleum contaminated soil was the best condition for gaseous methyl tert-butyl ether (MTBE) removal. It was found that H2SO4 modified bagasse AC in powder form had higher adsorption capacity (989.33 mg g−1) than that in bead form (1.94 mg g−1). In addition, bone biochar in powder form (3.51 mg g−1) also had higher adsorption capacity than that in bead form (1.63 mg g−1). This was the fact that material beads contained high moisture content that inhibited the penetration of gaseous MTBE into the material. And a mixed material of H2SO4 modified bagasse AC-bone biochar beads had the highest adsorption capacity (2.22 mg g−1) compared to individual H2SO4 modified bagasse AC beads (1.94 mg g−1) and bone biochar beads (1.63 mg g−1) due to a mixed material had more rough surface and high surface area on its material. So, gaseous MTBE can penetrate through this material more easily. Although the maximum adsorption capacity of H2SO4 modified bagasse AC in powder form was the highest but microorganism cannot sustain and survive in this form for a long time. Therefore, the material beads were more suitable for microorganism to grow and degrade gaseous MTBE. Microorganism can degrade MTBE and caused no secondary wastes. Moreover, A. indicus was a novel strain for MTBE removal that has not been previously reported. Therefore, a combination of A. indicus-mixed material beads was a good choice for MTBE removal in a biofilter system.
17442. 题目: Feeding behavior of the ocypodid crab Macrophthalmus japonicus and its effects on oxygen-penetration depth and organic-matter removal in intertidal sediments
期刊: Estuarine, Coastal and Shelf Science
作者: Bon Joo Koo, Sung-Han Kim, Jung-Ho Hyun
摘要: This study examined the poorly understood feeding behavior of the ocypodid crab Macrophthalmus japonicus in the field to explore its effects on oxygen-penetration depth (OPD) and organic-matter removal from intertidal sediments. An in situ investigation was conducted on an upper mud flat in the mouth of the Han River estuary, on the western coast of Korea. The behavior of M. japonicus and variation in the OPD within its habitat were surveyed and contents of organic materials such as organic carbon (OC), organic nitrogen (ON) and δ15N in its feeding pellets were compared as contrasted with non-feeding sediments during the daytime ebb in summer. We continuously recorded the surface activity of the crab during two main feeding periods and during a resting period, when the crabs remain immobile on the surface. Feeding periods exceeded 1 h; crabs fed on sediments more actively during the first feeding period (45 pseudo-pellets individual−1 h−1) than during the second feeding period (19 pseudo-pellets individual−1 h−1). The feeding period duration increased as body size decreased. Adult crabs devoted more of their time to basking in sunlight to dry their bodies, whereas young crabs spent most of their time feeding. Crab feeding activity on the surface generally enhanced the OPD. Conversely, OPD decreased during basking, when most crabs were immobile. Crab feeding greatly altered sediment geochemistry in the intertidal flat. In feeding pellets, OC and ON concentrations decreased to 55% and 60%, respectively, of those in non-feeding sediments. OC and ON were removed at rates of 1.89 mmol C m−2 h−1 and 0.24 mmol N m−2 h−1, respectively. The removal rate of OC by crab feeding was three-fold higher than that of OC mineralization by diffusive oxygen uptake (average: 0.56 mmol C m−2 d−1) and was comparable with the rate of anaerobic carbon mineralization (1.74–3.83 mmol m−2 h−1) in this region. The increase in the C/N ratio (10.6%–12.5%) and decrease in δ15N (7.21‰–5.99‰) in feeding pellets compared with non-feeding sediments indicate that M. japonicus removed N more selectively to meet requirements. These results imply that in situ crab activity significantly influenced OC and ON cycles; therefore, it is necessary to consider processes such as macroinvertebrate production and consumption when evaluating the purification function of intertidal sediments.
17443. 题目: Combination of humic acid and clay reduce the ecotoxic effect of TiO2 NPs: A combined physico-chemical and genetic study using zebrafish embryo
期刊: Science of The Total Environment
作者: Krupa Kansara, Ashutosh Kumar, Ajay S. Karakoti
摘要: The series of breakthroughs that have occurred within the realm of nanotechnology have been the source of several new products and technological interventions. One of the most salient examples in this regard is the widespread employment of titanium dioxide (TiO2) nanoparticles across a range of consumer goods. Given that waste is generated at every stage of the consumer-product cycle (from production to disposal), many items with TiO2 nanoparticles are likely to end up being discarded into water bodies. In order to understand the interaction of TiO2 NPs with aquatic ecosystem, the ecological fate and toxicity of TiO2 NPs was studied by exposing zebrafish embryos to a combination of abiotic factors (humic acid and clay) to assess its effect on the development of zebrafish embryos. The physiological changes were correlated with genetic marker analysis to holistically understand the effect on embryos development. Derjaguin–Landau–Verwey–Overbeek (DLVO) theory was used to analyze the interaction energy between TiO2 NPs and natural organic matter (NOM) for understanding the aggregation behavior of engineered nanoparticles (ENPs) in media. The study revealed that combination of HA and clay stabilized TiO2 NPs, compared to bare TiO2 and HA or clay alone. TiO2 NPs and TiO2 NPs + Clay significantly altered the expression of genes involved in development of dorsoventral axis and neural network of zebrafish embryos. However, the presence of HA and HA + clay showed protective effect on zebrafish embryo development. The complete system analysis demonstrated the possible ameliorating effects of abiotic factors on the ecotoxicity of ENPs.
17444. 题目: Molecular Composition of Hydrothermal Liquefaction Wastewater from Sewage Sludge and Its Transformation during Anaerobic Digestion
期刊: Journal of Hazardous Materials
作者: Shilai Hao, Shuang Ren, Nan Zhou, Huihui Chen, Muhammad Usman, Chen He, Quan Shi, Gang Luo, Shicheng Zhang
摘要: Anaerobic digestion (AD) has shown potential to convert hydrothermal liquefaction wastewater (HTLWW) into biogas in previous studies. However, the identification of refractory components and further insights into the molecular transformations of organics in HTLWW are essential for developing more efficient AD processes. In this study, two HTLWWs were obtained from the temperature-derived hydrothermal liquefaction of sewage sludge at 170 ℃ and 320 ℃. Their molecular compositions, as well as their modifications in the subsequent AD process, were characterized using a suite of advanced molecular tools. The dissolved organic matter (DOM) in the high temperature-derived HTLWW was lower in molecular weight, less saturated, less oxidized, and enhanced in nitrogenous substances. During the AD process, most of the volatile compounds and low molecular weight (LMW) neutrals were removed, while biopolymers were the most refractory. Carboxylic-rich alicyclic molecules (CRAM), particularly those containing 3 to 5 N for low temperature-derived DOM and 1 to 3 N for high temperature-derived DOM, were resistant to anaerobic biodegradation. Meanwhile, compounds with fewer nitrogens and more carboxyl groups were preferentially produced. This molecular characterization of HTLWW-derived DOM and examination of its transformation during AD will contribute to the development of efficient methods for HTLWW treatment in the future.
17445. 题目: Facile inverse micelle fabrication of magnetic ordered mesoporous iron cerium bimetal oxides with excellent performance for arsenic removal from water
期刊: Journal of Hazardous Materials
作者: Zhipan Wen, Jun Lu, Yalei Zhang, Gang Cheng, Shengnan Huang, Jin Chen, Rui Xu, Yin-an Ming, Yingru Wang, Rong Chen
摘要: In this study, magnetic ordered mesoporous Fe/Ce bimetal oxides (OMICs) were successfully synthesized via the modified sol-gel-based inverse micelle method. The textural/structure properties, surface chemistry and adsorption behavior of OMICs could be easily adjusted by using the calcination temperature. The sintering of samples would decrease the surface area, while expand the pore and crystallite size, which resulted in the formation of highly ordered inner-connected structure. Compared with pure mesoporous iron oxides (MI) and mesoporous cerium oxides (MC), this ordered mesoporous iron-cerium bimetal oxides (OMIC-3, 450 ℃) exhibited remarkable arsenic adsorption performance. The maximum adsorption capacities of As(III) and As(V) for OMIC-3 were 281.34 and 216.72 mg/g, respectively, and both As(III)/As(V) adsorption kinetics were well described by the pseudo-second order. The ionic strength and coexisting ions (except SiO32- and PO43-) did not affect arsenic removal, while humic acid (HA) significantly influenced on the arsenic removal even at a lower concentration. The adsorption mechanism study revealed that both the surface charge and surface M-OH groups of OMIC-3 were played the key roles in arsenic removal. The reusable property suggested that this magnetic OMIC-3 was a promising excellent adsorbent for decontamination of arsenic-polluted (especially As(III)-polluted) wastewater.
17446. 题目: Complexation of Arsenite, Arsenate, and Monothioarsenate with Oxygen-Containing Functional Groups of Natural Organic Matter: An XAS Study
期刊: Environmental Science & Technology
作者: Ashis Biswas, Johannes Besold, Carin Sjöstedt, Jon Petter Gustafsson, Andreas C. Scheinost, Britta Planer-Friedrich
摘要: Arsenic (As) is reported to be effectively sorbed onto natural organic matter (NOM) via thiol coordination and polyvalent metal cation-bridged ternary complexation. However, the extent of sorption via complexation with oxygen-containing functional groups of NOM is poorly understood. By equilibrating arsenite, arsenate, and monothioarsenate with purified model-peat, followed by As K-edge X-ray absorption spectroscopic analysis, this study shows that complexation with oxygen-containing functional groups can be an additional or alternative mode of As sorption to NOM. The extent of complexation was highest for arsenite, followed by monothioarsenate and arsenate. Complexation was higher at pH 7.0 compared to 4.5 for arsenite and arsenate and vice versa for monothioarsenate because of partial transformation to arsenite at pH 4.5. Modeling of the As K-edge extended X-ray absorption fine structure data revealed that As···C interatomic distances were relatively longer in arsenate- (2.83 ± 0.01 Å) and monothioarsenate-treated peat (2.80 ± 0.02 Å) compared to arsenite treatments (2.73 ± 0.01 Å). This study suggests that arsenite was predominantly complexed with carboxylic groups, whereas arsenate and monothioarsenate were complexed with alcoholic groups of the peat. This study further implies that in systems, where NOM is the major sorbent, arsenate and monothioarsenate can have higher mobility than arsenite.
17447. 题目: As(V) removal using biochar produced from an agricultural waste and prediction of removal efficiency using multiple regression analysis
期刊: Environmental Science and Pollution Research
作者: Sneh Lata, Roshan Prabhakar, Asok Adak, Sukha Ranjan Samadder
摘要: Arsenic contamination in drinking water is a matter of concern for many countries. An efficient and low-cost solution for this hazard is essentially needed on urgent basis. Therefore, in this study, banana pith (an agricultural waste) was used for biochar production and later it was modified with iron and applied for arsenic adsorption from aqueous solution. Produced biochar was characterized for proximate, ultimate, and surface analyses. Interestingly, after iron impregnation, the surface area of biochar increased (31.59 m2/g) by nearly 8 times. Morphological analysis showed that iron particles firmly held within the pores after impregnation. Arsenate (As(V)) adsorption behavior of iron-impregnated banana pith biochar was evaluated through a batch study by considering various parameters like dose, concentration, pH, temperature, and competing anions. Compared to impregnated biochar, raw biomass and its biochar showed a lesser affinity for arsenate in aqueous solution. The adsorption isotherm of As(V) on banana pith biochar was covered in the temperature range of 298 to 318 K, and kinetic data of adsorption was experimentally generated at 298 K. Langmuir model for the sorption isotherms and pseudo-second-order kinetic model for the sorption kinetics represented the experimental data. The thermodynamic study showed negative Gibb’s free energy (− 46.88 kJ/mol at 298 K, − 48.58 kJ/mol at 308 K, − 50.73 kJ/mol at 318 K) that suggested spontaneity of the adsorption process. Negative enthalpy (ΔH° = − 10.55 kJ/mol) showed exothermic nature of adsorption of arsenic, while negative entropy (ΔS° = 0.123 kJ/mol.K) suggested enthalpy-driven adsorption process. Mechanism of arsenic adsorption onto iron-impregnated banana pith biochar has also been discussed in detail. Based on the experimental observation, a predictive model for arsenate removal has been developed in this study. The findings of the present study elucidated that iron-impregnated banana pith biochar can be used as a low-cost adsorbing material for As(V) from aqueous solutions.
17448. 题目: A new incubation and measurement approach to estimate the temperature response of soil organic matter decomposition
期刊: Soil Biology and Biochemistry
作者: Yuan Liu, Nianpeng He, Li Xu, Jing Tian, Yang Gao, Shuai Zheng, Qing Wang, Xuefa Wen, Xingliang Xu, Kuzyakov Yakov
摘要: A reliable and precise estimate of the temperature sensitivity (Q10) of soil organic matter (SOM) decomposition is critical to predict feedbacks between the global carbon (C) cycle and climate change. In this study, we first summarize two commonly used approaches for estimating Q10 (Approach A: constant temperature incubation and discontinuous measurements, CDM model; Approach B: varying temperature incubation and discontinuous measurements, VDM model). We then introduced a newly developed approach (Approach C, VCM model) that combines rapidly varying temperature incubations and continuous measurements of SOM decomposition rates (Rs) that may be more realistic and suitable for Q10 estimation, especially for large scale estimation. Then, we conducted a 26-day incubation experiment using three different soils to compare the performance of these three approaches for estimating Q10 using R2 and P-values as indicators. Our results demonstrate that the fitting goodness of the exponential model was consistently higher for Approach C, with higher R2 values, lower confidence intervals, and lower P-values in almost all cases compared with Approaches A and B. Furthermore, results showed that Approaches A and B underestimated the Q10 value by 9.5–13% and 2.9–5.7%, respectively, in three different soils throughout the entire incubation period. Compared with traditional commonly used methods, the newly developed Approach C (VCM model) provides a more accurate and rapid estimation of the temperature response of SOM decomposition and can be used for large-scale estimation of Q10.
17449. 题目: Dissolved organic carbon dynamics in the East China Sea and the northwest Pacific Ocean
期刊: Ocean Science
作者: Ling Ding, Tiantian Ge, Xuchen Wang
摘要: Oceanic dissolved organic carbon (DOC) represents one of the largest carbon reservoirs on Earth, and its distribution and biogeochemical cycles play important roles in carbon cycling and other biogeochemical processes in the ocean. We report the distribution and concentrations of DOC for water samples collected from the shelf-edge and slope regions in the East China Sea (ECS) and the Kuroshio Extension (KE) in the northwestern North Pacific during two cruises in 2014–2015. The DOC concentrations were 45–88 µM in the ECS and 35–65 µM in the KE. In addition to biological processes that are estimated to account for 7 % and 8 %–20 % in shaping the DOC distribution in the ECS and KE regions, respectively, the DOC distribution is largely controlled by hydrodynamic mixing of different water masses. By comparing the DOC results with dissolved inorganic carbon (DIC) and dissolved inorganic radiocarbon (Δ14C-DIC) measured from the same water samples, we further demonstrate that the intrusion of the Kuroshio Current could dilute the DOC concentrations at stations in the outer shelf and slope regions of the ECS. The concentrations of DOC in the KE were significantly lower in surface waters than in the ECS, and a relatively low and stable DOC level (∼40 µM) was found in deep water (below 1500 m) at all stations. Based on the previously reported DIC and Δ14C-DIC values for the stations, the observed spatial variations of DOC in the upper 700 m among the stations in the KE were mainly influenced by mixing of the two water masses carried by the Kuroshio and Oyashio, the two dominant western boundary currents in the region. The hydrodynamic processes are thus important factors in the distribution and dynamics of DOC in the KE region.
17450. 题目: Dissolved organic carbon leaching from montane grasslands under contrasting climate, soil and management conditions
作者: Jin Fu, Rainer Gasche, Na Wang, Haiyan Lu, Klaus Butterbach-Bahl, Ralf Kiese
摘要: Grasslands are thought to be more vulnerable than many other ecosystems to climate change since their soils are characterized by high organic carbon contents and warming in montane regions is twice the global average rate. Despite these expected vulnerabilities, little is known about how climate change and management influence dissolved organic carbon (DOC) losses from montane grasslands and how relevant these losses are compared to other ecosystem carbon fluxes. In this study, 36 large (1 m2, 140 cm height) grassland lysimeters were filled with undisturbed soil monoliths and operated at three different sites located along an elevational gradient from 860 to 600 m a.s.l. From 2012 to 2014, changes in soil DOC concentrations and DOC leaching losses were quantified under different climate, soil and management (intensive vs. extensive; i.e., differing in the frequency of cutting and manuring events) conditions. The annual DOC leaching losses ranged between 6.6 and 27.5 kg C ha−1 year−1, which was only a minor (< 3%) component of the net ecosystem carbon exchange. DOC leaching losses were not affected by management intensity but were positively correlated with soil organic carbon in the top soil. Climate warming (~ + 2 °C) significantly increased DOC leaching rates for intensive (+ 43%) and extensive management (+ 58%), but only if simultaneous reductions in leachate were moderate. The DOC concentrations in soil water significantly decreased with soil depth. In 10, 30 and 50 cm DOC concentration were positively correlated with aboveground biomass production, indicating that plants play a crucial role in topsoil DOC dynamics. However, this relationship did not occur for DOC in soil water collected at 140 cm, suggesting that adsorption and degradation processes in the subsoil ultimately determine the dynamics of DOC losses below the rooting zone.
17451. 题目: Photocatalytic behavior of biochar-modified carbon nitride with enriched visible-light reactivity
作者: Lirong Meng, Wenhua Yin, Shengsen Wang, Xiaoge Wu, Jianhua Hou, Weiqin Yin, Ke Feng, Yong Sik Ok, Xiaozhi Wang
摘要: Ultra-thin layered structures and modified bandgaps are two efficient strategies to increase the photocatalytic performance of various materials for the semiconductor industry. In the present study, we combined both strategies in one material to form carbon-doped graphitic carbon nitride (g-C3N4) nano-layered structures by the method of melamine thermal condensation, in the presence of different mass ratios of biochar. The characterization showed that the composite with the best ratio retained the g-C3N4 polymeric framework and the bond with g-C3N4. The biochar was established via π–π stacking interactions and ether bond bridges. The π-conjugated electron systems provided from biochar can elevate charge separation efficiency. The ultra-thin structure also curtailed the distance of photogenerated electrons migrating to the surface and enlarge specific surface area of materials. The presence of carbon narrowed the bandgap and increased light absorption at a wider range of wavelengths of g-C3N4. The biochar/melamine ratio of 1:15 presented the best performance, 2.8 and 5 times faster than g-C3N4 degradating Rhodamine and Methyl Orange, respectively. Moreover, the catalyst presented a good stability for 4 cycles. In addition to that, biochar from waste biomass can be considered a sustainable, cost-effective, and efficient option to modify g–C3N4–based photocatalysts.
17452. 题目: Residual effects of biochar and phosphorus on growth and nutrient accumulation by maize (Zea mays L.) amended with microbes in texturally different soils
作者: Mazhar Rafique, Ibrahim Ortas, Muhammad Rizwan, Hassan Javed Chaudhary, Ali Raza Gurmani, Muhammad Farooq Hussain Munis
摘要: The purpose of study was to examine the residual effects of two types of biochar amendments, two phosphorus (P) fertilizer levels, phosphorus solubilizing bacteria (PSB) and arbuscular mycorrhizal fungs (AMF) on plant growth, nutrients absorption and root architecture of Zea mays L. in texturally different soils. Biochar signficantly increased nutrients absorption and plant biomass production with P-fertilization and microbial inoculantion. Texturally different soils enhanced the plant biomass and nutrients absorption in their independent capacity on addition of biochar, microbial inoculants and P-fertilization. It was shown that mycorrhizal inoculation had positive influence on plant root and shoot biomass in both soils irrespective to the biochar type used. Root colonization was notably increased in biochar + mycorrhizae (B + M) inocultaed plants. It was shown that mycorrhizal inoculation had positive influence on nutrients absorption by plant roots and it had high content of P, potassium, calcium and magnesium in plants at all biochar and P levels. Without P fertilization, biochar amendments significantly promoted shoot P content and root colonization. The P application significantly influenced soil microbial activity in terms of nutrient concentration and plant growth. Root attributes were significantly inclined by microbial inoculation. Residual effects of biochar and P significantly enhanced the nutreints absorption and maize plant growth. Thus, we concluded that residual biochar and P fertilizer showed positive effects on nutrients absorption and maize plant growth promotion in differently textured soils. Microbial inoculants further stimulated the plant biomass production and nutrients absorption due to effective root colonization.
17453. 题目: Effects of fish culture on particulate organic matter in a reservoir-type river as revealed by absorption spectroscopy and fluorescence EEM-PARAFAC
作者: Hui Wang, Yonghao Wang, Wan-E Zhuang, Wei Chen, Weixin Shi, Zhuoyi Zhu, Liyang Yang
摘要: Dam construction and fish culture can change the biogeochemical processes in river, yet their impact on the spectral properties of particulate organic matter (POM) remains to be studied. This was investigated in a reservoir-type river (Minjiang river, SE China) using absorption spectroscopy and fluorescence excitation-emission matrices-parallel factor analysis (EEMs-PARAFAC). Five fluorescent components were identified from POM with PARAFAC. Four components C1–C4 were affected by the seasonal variations of rainfall and runoff, indicating the influences of hydrological condition and terrestrial inputs. The Chlorophyll a concentration (Chl a) correlated significantly with the humic-like C3 (p < 0.05) and the protein-like C4 (p < 0.01), indicating phytoplankton was an important source of C3 and C4. The Chl a and fluorescence intensities of C3–C4 were higher in the fish culture zones than in other areas, and the absorption coefficient a300 and C1–C4 were lower downstream the dam. These results indicated that fish farming in the reservoir probably promoted the production of POM. The a300 and C1 per unit mass of suspended particulate matter (a300/TSM and C1/TSM) correlated significantly with the median particle size (p < 0.01), which might be related to the contribution of micro-phytoplankton. The absorption spectra of POM showed a shoulder peak at ∼280 nm, and its intensity correlated significantly and positively with Chl a (p < 0.01). These results indicated that the peak was probably derived from phytoplankton production. Our results have implications for better understanding the influences of human activities on the dynamics of river POM.
17454. 题目: Composition of the dissolved organic matter produced during in situ burning of spilled oil
期刊: Organic Geochemistry
作者: Aprami Jaggi, Jagoš R. Radović, Lloyd R. Snowdon, Stephen R. Larter, Thomas B.P. Oldenburg
摘要: In situ burning is often used as a response method for oil slicks in the marine environment. This process however forms viscous tar-like residues that either float on the surface or sink through the water column, introducing organic species into the water phase. The interaction of this burn residue with the water phase also introduces dissolved organics into the water column. In this study, we conducted laboratory-scale experiments to characterize and compare the organic species entering the water phase from the petrogenic (fresh oil) and pyrogenic (burnt oil) input during oil spills. The oil and water-soluble organics were characterized using ultra-high-resolution mass spectrometry (FTICR-MS). The results show that burning strongly increases concentrations of oil-related constituents entering the water phase, due to transformation reactions producing oxidized organic species with higher water solubility. The pyrogenic water-soluble organics also showed a higher percentage of unsaturated compounds relative to the petrogenic fraction. The effect of these highly unsaturated and oxygenated organic species on oil spill fate and their ecosystem impacts is currently unknown.
17455. 题目: Sediment properties of lithologic units and their correlation within the lower delta plain of the Nakdong River Delta, southeast Korea
期刊: Quaternary International
作者: Boo-Keun Khim, Seungwon Shin, Jin Cheul Kim, Hiroyuki Takata, Sangmin Hyun, Daekyo Cheong
摘要: Multi-proxy sediment properties reveal that three cores (ND-01, ND-02, and ND-03) from the lower delta plain of the Nakdong River Delta, southeast Korea, are characterized by the same stratigraphic lithologic successions consisting of a upper sand unit (10–15 m thick and <1 ka), a middle mud unit (∼20 m thick and 1–9 ka), a lower sand unit (6–9 m thick and 9–10 ka), and a lower mud unit (10–15 m thick and >10 ka) overlying weathered gravelly fluvial sediments and weathered bedrock. The sediment properties of each lithologic unit are controlled by the balance between the marine influence from Holocene sea level rise and the freshwater influence from Nakdong River discharge. In particular, the middle mud unit is characterized by distinct peaks in CaCO3 content, P/T ratios (the ratio of planktonic foraminifera to the sum of benthic and planktonic foraminifera), total organic carbon and total nitrogen contents, and δ13Corg values at 7–8 ka, which indicates that the maximum marine forcing during the sea level rising and the greatest influence of the Tsushima Warm Current during the evolution of the river-mouth coastal depositional system from an estuarine to a deltaic environment. Although the vertical stacking of lithologic successions is stratigraphically consistent within the lower delta plain, the precise temporal evaluation and comprehensive depositional evolution in the Nakdong River Delta including the upper delta plain and the prodelta zones remain a topic of future investigation.
17456. 题目: Past climate changes over South Korea during MIS3 and MIS1 and their links to regional and global climate changes
期刊: Quaternary International
作者: Sujeong Park, Jaesoo Lim, Hyoun Soo Lim
摘要: To test past climate change in central Korea in terms of latitudinal differences over the Korean Peninsula, we reconstructed relative abundances between C3 and C4 plants in Hanam area based on sedimentary total organic carbon isotope values (δ13CTOC) of a 2.8 m long trench in an archeological site and compared these data with climate changes at different latitudes of Korea. During marine isotope stage 3 (MIS3) corresponding to past 60,000–25,000 years, the millennial-timescale fluctuations of the δ13CTOC values in Hanam were more similar to those in Hongcheon located in the inner mountain area of central Korea than those in Cheollipo area in west coast of Korea. Periods with significantly decreased δ13CTOC values representing decreased C4 plants under wetter climates in these two inland areas are comparable with millennial-timescale Dansgaard–Oeschger (D-O) warming events recorded in Greenland ice cores, suggesting strong climatic teleconnection between East Asia and subpolar areas during the last glacial period. During MIS1 (Holocene), the changes in vegetation and climate in Hanam have been influenced by the long-term summer monsoon changes. Regarding past latitudinal change in aridity or humidity over Korea, during the middle Holocene, δ13CTOC values in areas of central South Korea gradually decreased, suggesting moving to a more humid climate. This is contrary to the increasing δ13CTOC values in southern South Korea indicating more dry climates. Furthermore, it is likely that there were two severe dry climates at different times at different latitudes (1000 cal BP in Hanam in northern South Korea and 2500 cal BP in Geoje in southern South Korea), suggesting possible different climate changes at millennial timescales over Korea.
17457. 题目: Field demonstration of enhanced removal of chlorinated solvents in groundwater using biochar-supported nanoscale zero-valent iron
期刊: Science of The Total Environment
作者: Linbo Qian, Yun Chen, Da Ouyang, Wenying Zhang, Lu Han, Jingchun Yan, Petr Kvapil, Mengfang Chen
摘要: The application of biochar-supported nanoscale zero-valent iron (biochar-nZVI) was successfully implemented in a field demonstration for the first time. To overcome the significant shortcomings of nZVI agglomeration for in-situ groundwater remediation, biochar-nZVI was injected into groundwater using direct-push and water pressure driven packer techniques for a site impacted by chlorinated solvents in the North China Plain. The field demonstration comprising two-step injections was implemented to demonstrate the effectiveness of nZVI and biochar-nZVI respectively. The outcome of the demonstration revealed a sharp reduction of contaminant concentrations of chlorinated solvents in 24 h following the first injection of nZVI, but the rebound of the concentrations of these contaminants in groundwater has occurred within the next two weeks. However, application of biochar-nZVI greatly enhanced the removal of chlorinated solvents in groundwater over the longer period of 42 days. The enhanced removal of chlorinated solvents in groundwater by biochar-nZVI is mainly attributed to the synergistic effects of adsorption and reduction. The adsorption by biochar significantly reduced the level of chlorinated solvents in groundwater. Overall increases in ferrous iron and chloride concentrations after the injections indicated that the reduction has occurred during the removal of chlorinated solvents in groundwater. In summary, biochar-supported nZVI could be potentially used for the effective remediation of chlorinated solvents in groundwater.
17458. 题目: Enhanced removal of hexavalent chromium by engineered biochar composite fabricated from phosphogypsum and distillers grains
期刊: Science of The Total Environment
作者: Guoqi Lian, Bing Wang, Xinqing Lee, Ling Li, Taoze Liu, Wenqiang Lyu
摘要: Two kinds of industrial wastes (distillers grains and phosphogypsum) were used as raw materials to produce a new biochar composite for Cr(VI) removal in water. The influencing factors including pyrolysis temperature, dosage, initial solution pH as well as contacting time were explored. The adsorption kinetics, isotherms, and thermodynamics of two biochars were conducted. The results show that the adsorption of Cr(VI) by biochar is related to pH. The ideal pH was 3.0 and the adsorbed Cr(VI) decreases as the pH increases. The Cr(VI) adsorption process conformed to the pseudo-second-order equation. Phosphogypsum modified (PM)-biochar is well described by the Freundlich model. The maximum adsorption capacities of distillers grains (DG)-biochar and PM-biochar on Cr(VI) were 63.1 and 157.9 mg g−1, respectively. The thermodynamic analysis indicates that the Cr(VI) adsorption occurs spontaneously which is an endothermic process. This study provided an alternative way for Cr(VI) removal from water.
17459. 题目: Enhanced thallium(I) removal from wastewater using hypochlorite oxidation coupled with magnetite-based biochar adsorption
期刊: Science of The Total Environment
作者: Huosheng Li, Jingfang Xiong, Gaosheng Zhang, Aiping Liang, Jianyou Long, Tangfu Xiao, Yongheng Chen, Ping Zhang, Dandan Liao, Lianhua Lin, Hongguo Zhang
摘要: The development of efficient and regenerable adsorbent coupled with advanced oxidation for enhanced thallium (Tl) removal has been a recent focus on wastewater treatment. In this study, a magnetite-based biochar derived from watermelon rinds was synthesized and used as a sustainable adsorbent and catalyst for hypochlorite oxidation and removal of Tl(I) from wastewater. The addition of hypochlorite substantially enhanced the Tl(I) removal under normal pH range (6–9). Maximum Tl adsorption capacity of 1123 mg/g was achieved, which is 12.3% higher than the highest value previously reported. The magnetic biochar can be regenerated using 0.1 mol/L HNO3 solution for elution in only 5 min, with a Tl desorption efficiency of 78.9%. The Tl removal efficiency was constantly higher than 98.5% during five consecutive recycle tests, indicating the effective reuse performance of the adsorbent. Oxidation, surface precipitation, pore retention and surface complexation were the main mechanisms for Tl(I) removal. The re-dissolution of Tl compounds and ion exchange of Tl cations with proton were the main mechanisms for adsorbent regeneration. Given the fast oxidation rate, high adsorption capacity, steady reusability and facile separability, this magnetic biochar-hypochlorite technique is a promising means for Tl(I) removal from wastewater. The catalytic hypochlorite oxidation induced by the magnetic biochar has also great potential to the effective removal of other pollutants.
17460. 题目: Pyrolysis characteristics of soil humic substances using TG-FTIR-MS combined with kinetic models
期刊: Science of The Total Environment
作者: Tingting Li, Fanhao Song, Jin Zhang, Shasha Liu, Baoshan Xing, Yingchen Bai
摘要: The incorporation and cycling of pyrogenic organic matter in soil is a potential carbon sink, while the pyrolysis behaviors of soil organic matter are still lacking. Pyrolysis characteristics of soil fulvic acid (FA) and humic acid (HA) were investigated using thermogravimetry combined with Fourier transform infrared spectrometer-mass spectrometer (TG-FTIR-MS) and kinetic models. Four reaction stages corresponding to four pseudo-components were distinguished for both FA and HA. FA exhibited greater transformation contributions of hemicellulose-like and cellulose-like pseudo-components, while HA exhibited greater transformation contributions of lignin-like pseudo-components. Compared to HA, higher levels of heat-resistant aromatic compounds, phenolic groups, and carboxylic groups were recognized in FA. Values of both activation energy (Ea, 246.13–661.40 kJ·mol−1) and pre-exponential factor (lnA, 53.49–107.16 min−1) of FA were greater than corresponding Ea (241.74–466.70 kJ·mol−1) and lnA (51.99–74.36 min−1) values of HA determined by Flynn-Wall-Ozawa method and Distributed Activation Energy Model. The main pyrolysis reaction mechanisms of both FA and HA closely matched with the order-based model corresponding to 2nd and 3rd order random nucleation on an individual particle. The evolved gas species of H2, CH4, H2O, and CO2 were dominant for FA and HA pyrolysis. Generally, the total H2/CO2 and CH4/H2O releases were relatively larger for FA and HA pyrolysis, respectively. TG-FTIR-MS is shown to be an effective method to provide valuable and qualitative analysis of the gaseous volatile species evolved during HS pyrolysis. Findings from this systematic study of soil organic matter responding to pyrolysis will be critical for predicting the changes of soil systems or carbon cycle affected by future climate and fire regimes.