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22821. 题目: Elucidating the role of earthworms for the formation of organo-mineral associations in soil
文章编号: N20031905
期刊: Soil Biology and Biochemistry
作者: T. Guhra, K. Stolze, S. Schweizer, K.U. Totsche
更新时间: 2020-03-19
摘要: Earthworms are considered as ecosystem engineers impacting soil properties as well as nutrient and element cycles. To facilitate their movement through the soil, earthworms excrete extracellular polymeric substances, commonly referred to as earthworm cutaneous mucus. This type of biogenic organic matter may serve as nutrient source for plants and microorganisms. While the impact of earthworms burrowing through and ingesting the soil as well as earthworm-formed aggregate properties are rather well studied, still little is known about the interaction of mucus with soil constituents. The objective of this study was to investigate the small-scale interactions between earthworm mucus and secondary soil minerals, e.g. goethite and illite, and the resulting formation of organo-mineral associations. For this, we characterized the chemical composition of earthworm mucus by FTIR and 13C-NMR and compared the findings with those of microbial EPS as abundant and well investigated type of organic matter in soil. Mucus from anecic (Lumbricus terrestris L.) and endogeic (Aporrectodea caliginosa Sav.) earthworm species was dominated by proteins and carbohydrates. Adsorption to illite and goethite was pronounced and accompanied by a distinct compositional fractionation of mucus between the solid and liquid phase especially for goethite as shown by the investigation of mineral-freed supernatants after conducting completely mixed batch reactor experiments. Furthermore, we identified the formation of organo-mineral associations and determined the surface charge by measuring the isoelectric point (IEP). The IEP of mucus-goethite associations was lower while the IEP of mucus-illite associations was higher than the corresponding pure mineral phase. Our results show that the specific adsorption of earthworm mucus constituents to soil minerals results in the formation of mucus-mineral associations. These associations contribute to the enrichment of nutrient elements in the drilosphere and earthworm-formed aggregates. Furthermore, they explain the altered properties of earthworm-formed aggregates in comparison to the earthworm unaffected bulk soil material.

22822. 题目: Urbanization increases carbon concentration and pCO2 in subtropical streams
文章编号: N20031904
期刊: Environmental Science and Pollution Research
作者: Michelle das Neves Lopes, Cleiton Juarez Decarli, Lorena Pinheiro-Silva, Thiago Cesar Lima, Nei Kavaguichi Leite, Mauricio Mello Petrucio
更新时间: 2020-03-19
摘要: Urbanization growth may alter the hydrologic conditions and processes driving carbon concentrations in aquatic systems through local changes in land use. Here, we explore dissolved carbon concentrations (DIC and DOC) along urbanization gradient in Santa Catarina Island to evaluate potential increase of CO2 in streams. Additionally, we assessed chemical, physical, and biotic variables to evaluate direct and indirect effects of urbanization in watersheds. We defined 3 specific urbanization levels: high (> 15% urbanized area), medium (15–5% urbanized area), and low (< 5% urbanized area) urbanization. The results showed that local changes due to growth of urban areas into watersheds altered the carbon concentrations in streams. DOC and DIC showed high concentrations in higher urbanization levels. The watersheds with an urban building area above 5% showed pCO2 predominantly above the equilibrium with the atmosphere. These findings reveal that local modifications in land use may contribute to changes in global climate by altering the regional carbon balance in streams.

22823. 题目: Life cycle assessment of biochar-to-soil systems: A review
文章编号: N20031903
期刊: Journal of Cleaner Production
作者: Jan Matuštík, Tereza Hnátková, Vladimír Kočí
更新时间: 2020-03-19
摘要: The climate change and soil degradation are among the most prominent environmental issues of today and solutions need to be looked for. Pyrolysis of (waste) biomass to produce biochar that is then applied to agricultural soil could be one of the means to tackle these problems. Many authors have used the Life Cycle Assessment method to evaluate the environmental impact of biochar-to-soil projects and in this paper those studies are systematically reviewed to uncover the overall trend. Although the differences in the contexts and characteristics of these studies disallow direct comparison of results, it is still obvious that the application of biochar brings significant benefits, either to neutralize the greenhouse gas emission of agricultural production or as a carbon capture method. There is also a great potential for energy production by utilizing the co-products - syngas and bio-oil. The benefits of carbon sequestration in biochar and the energy production usually overcompensate the greenhouse gas emissions produced during feedstock production and handling. However, the effect on other impact categories needs to be evaluated and limited and the economic sustainability of the project needs to be assured. To facilitate future progress, some methodology unification would be beneficial.

22824. 题目: Diffuse nitrogen pollution in a forest-dominated watershed: Source, transport and removal
文章编号: N20031902
期刊: Journal of Hydrology
作者: Pengtao Wang, Wei Ouyang, Zeshan Wu, Xintong Cui, Weihong Zhu, Ri Jin, Chunye Lin
更新时间: 2020-03-19
摘要: Along with gradually controlled point source discharges, diffuse nitrogen pollution has become an important cause of eutrophication. Diffuse nitrogen export from forests is an inherent characteristic, and increasing human disturbance aggravates this process. To control diffuse nitrogen pollution effectively, it is of great significance to determine the source, transport path and removal method of diffuse nitrogen export in forest-dominated watersheds. Long-term variations in the nitrogen concentrations indicate that nitrate and dissolved organic nitrogen (DON) are the main diffuse nitrogen export forms in the Buerhatong River watershed (BRW). Thus, the Soil and Water Assessment Tool (SWAT) hydrological model is conducted to simulate diffuse nitrate and DON export. First, main source of diffuse nitrate and DON export is determined by the fitting results of nitrogen contribution and forest/farmland cover. Then, the relationship between nitrogen export from forest/farmland and main hydrologic streamflow is explored. Finally, the role of wetlands in the diffuse nitrogen load removal is analyzed, and sensitivity results by Monte Carlo simulation of nitrogen export from wetlands, forests and farmlands are compared. The average annual diffuse nitrate and DON export values are 1.19 and 0.43 kg ha−1 yr−1, respectively, from 2014 to 2017. When forest cover and farmland cover are higher than 70% and 5%, farmlands and forests are the main sources of diffuse nitrate and DON export, respectively. Lateral flow is the dominant transport path of DON export from forests and nitrate export from farmlands, with correlation coefficient of 0.73 and proportion of 98%, respectively. Wetlands have the ability to reduce the diffuse nitrogen load, and their efficiency is related to the relative geographic location. The in situ experimental results show that the nitrate and DON removal rates by wetlands are 24.46% and 11.71%, respectively. The sensitivity of forest and wetland for diffuse nitrate and DON load removal is 0.31, −0.12 and 0.2, −0.21, respectively. Returning forests to wetlands is a good method for diffuse nitrogen removal with food production taken into consideration.

22825. 题目: Effect of Microbial Biomass and Humic Acids on Abiotic and Biotic Magnetite Formation
文章编号: N20031901
期刊: Environmental Science & Technology
作者: Xiaohua Han, Elizabeth J. Tomaszewski, Julian Sorwat, Yongxin Pan, Andreas Kappler, James M. Byrne
更新时间: 2020-03-19
摘要: Magnetite (Fe3O4) is an environmentally ubiquitous mixed-valent iron (Fe) mineral, which can form via biotic or abiotic transformation of Fe(III) (oxyhydr)oxides such as ferrihydrite (Fh). It is currently unclear whether environmentally relevant biogenic Fh from Fe(II)-oxidizing bacteria, containing cell-derived organic matter, can transform to magnetite. We compared abiotic and biotic transformation: (1) abiogenic Fh (aFh); (2) abiogenic Fh coprecipitated with humic acids (aFh-HA); (3) biogenic Fh produced by phototrophic Fe(II)-oxidizer Rhodobacter ferrooxidans SW2 (bFh); and (4) biogenic Fh treated with bleach to remove biogenic organic matter (bFh-bleach). Abiotic or biotic transformation of Fh was promoted by Feaq2+ or Fe(III)-reducing bacteria. Feaq2+-catalyzed abiotic reaction with aFh and bFh-bleach led to complete transformation to magnetite. In contrast, aFh-HA only partially (68%) transformed to magnetite, and bFh (17%) transformed to goethite. We hypothesize that microbial biomass stabilized bFh against reaction with Feaq2+. All four Fh substrates were transformed into magnetite during biotic reduction, suggesting that Fh remains bioavailable even when associated with microbial biomass. Additionally, there were poorly ordered magnetic components detected in the biogenic end products for aFh and aFh-HA. Nevertheless, abiotic transformation was much faster than biotic transformation, implying that initial Feaq2+ concentration, passivation of Fh, and/or sequestration of Fe(II) by bacterial cells and associated biomass play major roles in the rate of magnetite formation from Fh. These results improve our understanding of factors influencing secondary mineralization of Fh in the environment.

22826. 题目: Emission characteristics of polybrominated diphenyl ethers from the thermal disassembly of waste printed circuit boards
文章编号: N20031812
期刊: Atmospheric Environment
作者: Shufei Tan, Zhenyu Chen, Rui Wang, Jie Guo, Zhenming Xu
更新时间: 2020-03-18
摘要: Thermal disassembly is prevalently applied for the removal of electronic components on waste printed circuit boards (WPCBs), and temperature is an important factor influencing the pollutant emission process. The emission characteristics of polybrominated diphenyl ethers (PBDEs) to the environment under thermal stress were investigated by conducting both bench-scale experiments and pilot-scale experiments over a temperature range from 100 to 260 °C. Bench-scale experiments showed that the emission factors (EFs) for ∑39PBDEs from WPCB powder were obviously higher than those from WPCB fragments. Mono-to tri-BDEs predominated the PBDEs emission at each temperature, and the EFs for the mono-to tri-BDEs from WPCB powder ranged from 232 to 3280 ng/g, respectively. Pilot-scale experiments were done to study the particulate matter (PM) and PBDEs emitted from WPCBs mounted with electronic components using a thermal disassembly machine. The mass of the PM and PBDEs released from WPCBs during heating increased with increasing temperature. A bimodal distribution pattern for the PM with peaks at diameters of 0.4–0.7 and 5.8–9.0 μm was observed. The values of the EFs for ∑39PBDEs varied from 6.41 to 674 ng/g, which were comparable with those calculated from WPCB fragments in the bench-scale experiments. The mass distribution of the ∑39PBDEs in the PM predominated in the size fraction of >9.0 μm and 0.7–1.1 μm at 100 and 260 °C, respectively. The highly brominated PBDEs (hexa- and hepta-BDEs) had a mass median aerodynamic diameter (MMAD) greater than 2.5 μm, while the lightly brominated PBDEs (mono-to penta-BDEs) were mainly distributed in finer particles, with a MMAD of less than 2.5 μm. The particle size distribution of PBDEs was significantly correlated with the distribution of organic carbon (OC) in PM. All these results can provide basic data for gas pollution related to PBDEs and its control for electronic waste recycling.

22827. 题目: Radiocarbon in dissolved organic and inorganic carbon of the South China Sea
文章编号: N20031811
期刊: Journal of Geophysical Research: Oceans
作者: Ling Ding, Yuanzhi Qi, Sen Shan, Tiantian Ge, Chule Luo, Xuchen Wang
更新时间: 2020-03-18
摘要: We present the carbon isotope (14C and 13C), dissolved inorganic carbon (DIC), and dissolved organic carbon (DOC) concentration measurements in the South China Sea (SCS) to reveal the different sources and cycling time scales of the two major carbon pools in the SCS. The DIC concentrations ranged from 1776 μmol kg‐1 to 2328 μmol kg‐1, and they were lower at the surface and increased with depth. Conversely, the DOC concentrations ranged from 38 μM to 95 μM, and they were higher on the surface and decreased rapidly in the upper 500‐m water depth. The DIC Δ14C and DOC Δ14C values varied from ‐227‰ to 68‰ and ‐557‰ to ‐258‰, respectively, and both decreased with depth until 1500 m and then remained relatively constant. DOC Δ14C values were ‐330‰ lower than DIC Δ14C, indicating that DOC has cycled for much longer than DIC in the SCS. The lower Δ14C‐DIC and Δ14C‐DOC values at depths shallower than 700 m were mainly influenced by intensified vertical mixing, which upwelled the deep water with low Δ14C‐DIC and Δ14C‐DOC values for thorough mixture with the upper layer water. Conversely, the small difference in the Δ14C signature in deep water (> 1500 m) between the SCS and the North Pacific (NP) confirmed the rapid water exchange through the Luzon Strait and rapid water mixing in the SCS basin, which plays an important role in controlling carbon cycling in the deep SCS.

22828. 题目: Methane oxidation dynamics in a karst subterranean estuary
文章编号: N20031810
期刊: Geochimica et Cosmochimica Acta
作者: David Brankovits, John W. Pohlman
更新时间: 2020-03-18
摘要: Chemical gradients between fresh, brackish and saline waters shape biogeochemical reactions and organic matter transformation within subterranean estuaries. In the Yucatán Peninsula's karst subterranean estuary (KSE), methane and dissolved organic matter generated during the anaerobic decomposition of tropical forest vegetation are transported into flooded cave networks where microbial consumption greatly reduces their concentrations in the groundwater. To test the hypothesis that chemoclines associated with salinity gradients of the KSE are sites of methane oxidation, we obtained methane concentration and δ13C profiles of unprecedented vertical resolution from within a fully-submerged cave system located 6.6 km inland from the coastline using the 'OctoPiPi' (OPP) water sampler. Along a 12-24 cm thick low-salinity-halocline at ∼4.5 m water depth, salinity increased from fresh to brackish (0.2 to 1.8 psu), methane concentrations decreased, and δ13C values increased, as expected for microbial methane oxidation. The underlying brackish water had elevated oxygen concentrations compared to the always anoxic freshwater, suggesting that aerobic methane oxidation is the dominant process facilitating methane consumption. By contrast, as salinity increased from 1.8 to 36 psu through a 24-36 cm thick high-salinity-halocline between the meteoric lens and the saline groundwater at ∼20 m water depth, methane concentrations and δ13C values were constant. Conservative mixing and kinetic isotope models incorporating the methane data confirm a hotspot for microbial methane oxidation at the low-salinity-halocline. At least 98% of methane originating in the anoxic freshwaters was removed before its transport via channelized flow towards the coastline. These findings provide novel insight into the spatial constraints of methane dynamics within a karst subterranean estuary.

22829. 题目: Are nitrous oxide emissions indirectly fueled by input of terrestrial dissolved organic nitrogen in a large eutrophic Lake Taihu, China?
文章编号: N20031809
期刊: Science of The Total Environment
作者: Yongqiang Zhou, Qitao Xiao, Lei Zhou, Kyoung-Soon Jang, Yunlin Zhang, Mi Zhang, Xuhui Lee, Boqiang Qin, Justin D. Brookes, Thomas A. Davidson, Erik Jeppesen
更新时间: 2020-03-18
摘要: Lakes actively transform nitrogen (N) and emit disproportionately large amounts of N2O relative to their surface area. Studies have investigated the relative importance of denitrification or nitrification on N2O emissions; however, the linkage between N2O efflux and dissolved organic nitrogen (DON) and carbon (DOC) remains largely unknown. Long-term (2012–2017) seasonal field observations and a series of degradation experiments were used to unravel how DON composition impacts N2O emissions from Lake Taihu, China. In the northwestern part of the lake, large riverine inflow and high N2O emissions occur in all seasons (24.6 ± 25.2 μmol m−2 d−1), coincident with high levels of terrestrial DON and DOC. The degradation of labile DON and DOC likely enhanced ammonification as supported by the correlations between NH4+-N and DON, DOC, a(350), and terrestrial humic-like C3. The area with large riverine inputs in the northwestern part of the lake was characterized by low DO which may enhance incomplete aerobic nitrification and incomplete denitrification, both leading to N2O production. Twenty days laboratory experiments indicated greater N2O production in the northwest inflow samples (N2O on day 20: 120.9 nmol L−1 and 17.3 nmol L−1 for bio- and photo-degradation samples, respectively) compared with the central lake samples (N2O on day 20: 20.3 nmol L−1 and 12.3 nmol L−1 for bio- and photo-degradation samples, respectively), despite both having low Chl-a. Our bio- and photo-degradation of DON and DOC experiment confirmed the occurrence of ammonification along with consumption of NH4+-N and thereafter NO3−-N. Our results collectively suggest that terrestrial DON fueled ammonification, enhanced nitrification and incomplete denitrification, and thereby became an important contributor to the N2O efflux from Lake Taihu.

22830. 题目: Fate and removal of antibiotic resistance genes in heavy metals and dye co-contaminated wastewater treatment system amended with β-cyclodextrin functionalized biochar
文章编号: N20031808
期刊: Science of The Total Environment
作者: Ji-wen Wu, Cong-rong Wu, Chun-shuang Zhou, Li-li Dong, Bing-feng Liu, De-feng Xing, Shan-shan Yang, Jia-ning Fan, Li-ping Feng, Guang-li Cao, Shi-jie You
更新时间: 2020-03-18
摘要: Biochar has been received increasing concerns regarding its environmental effect, which is promising in wastewater treatment. In this study, the performance of β-cyclodextrin functionalized biochar (β-BC) on the removal of antibiotic resistance genes (ARGs) in wastewater treatment under the co-stresses of heavy metals and dye is evaluated. Results show that when 20 mg/L heavy metals (HMs) and 150 mg/L methyl orange (MO) are present in daily fed influent, only 0.05 mg/L HMs residual and 96.79%–98.84% MO removal efficiency achieved in β-BC additive group, compare to 0.16 mg/L and 87.92%–94.11% of that in control, respectively, indicating that β-BC can benefits the performance of contaminants removal. To evaluate the role of β-BC plays on ARGs in multi-contaminants stressed system, tet W, tet M, sul-1, sul-2, blaTEM, oxa-1, qnr-S, erm-B and intI-1 are identified. The relative abundance of all identified ARGs are decreased when β-BC presence compared to the corresponding groups without β-BC additive. The diversity and composition of microbial community are explored and the reduction of potential antibiotic-resistant bacteria is speculated as a driver of ARGs removal. In conclusion, our study demonstrates that β-BC possesses the ability to promote the removal of ARGs during continuous wastewater treatment under HMs-MO co-contaminant.

22831. 题目: Ammonia and phosphorus removal from agricultural runoff using cash crop waste-derived biochars
文章编号: N20031807
期刊: Frontiers of Environmental Science & Engineering
作者: Alisa Salimova, Jian’e Zuo, Fenglin Liu, Yajiao Wang, Sike Wang, Konstantin Verichev
更新时间: 2020-03-18
摘要: Adsorption of biochars (BC) produced from cash crop residuals is an economical and practical technology for removing nutrients from agricultural runoff. In this study, BC made of orange tree trunks and tea tree twigs from the Laoguanhe Basin were produced and modified by aluminum chloride (Al-modified) and ferric sulfate solutions (Fe-modified) under various pyrolysis temperatures (200°C–600°C) and residence times (2–5 h). All produced and modified BC were further analyzed for their abilities to adsorb ammonia and phosphorus with initial concentrations of 10–40 mg/L and 4–12 mg/L, respectively. Fe-modified Tea Tree BC 2h/400°C showed the highest phosphorus adsorption capacity of 0.56 mg/g. Al-modified Orange Tree BC 3h/500°C showed the best performance for ammonia removal with an adsorption capacity of 1.72 mg/g. FTIR characterization showed that P = O bonds were formed after the adsorption of phosphorus by modified BC, N-H bonds were formed after ammonia adsorption. XPS analysis revealed that the key process of ammonia adsorption was the ion exchange between K+ and NH4+. Phosphorus adsorption was related to oxidation and interaction between PO43 and Fe3+. According to XRD results, ammonia was found in the form of potassium amide, while phosphorus was found in the form of iron hydrogen phosphates. The sorption isotherms showed that the Freundlich equation fits better for phosphorus adsorption, while the Langmuir equation fits better for ammonia adsorption. The simulated runoff infiltration experiment showed that 97.3% of ammonia was removed by Al-modified Orange tree BC 3h/500°C, and 92.9% of phosphorus was removed by Fe-modified Tea tree BC 2h/400°C.

22832. 题目: Continuous aridification since the mid-Holocene as the main cause of C 3 /C 4 dynamics in the grasslands of Northeastern China
文章编号: N20031806
期刊: European Journal of Soil Science
作者: N. Li, M. Xie, D. Sack, N. Dubois, X. Yang, G. Gao, D. Li, L. Liu, H. Liu, C. Leng, J. Wang, B. Liu, D. Jie
更新时间: 2020-03-18
摘要: Ecological responses to past climate change as determined from palaeorecords offer insights into responses that may accompany future climate change. In arid and semi‐arid lands, the interactions between regional vegetation and climate change are not yet well understood partly due to a lack of suitable palaeovegetation proxies that can provide accurate and continuous tracers for past vegetation dynamics. To gain a better understanding of long‐term vegetation dynamics, this study employs a multiproxy approach applied to sand‐palaeosol sediments of northeastern China's Songnen grasslands. Phytolith analyses and data on the stable carbon isotope composition (δ13C) of organic matter are used to reconstruct palaeovegetation composition, namely, the changing abundance of C3 and C4 species, whereas a geochemical weathering index (Fed/Fet ratios) tracks past East Asian summer monsoon (EASM) intensity. The phytolith assemblages and indices and δ13C of the soil indicate that C4 species abundance has been increasing in the Songnen grasslands since the mid‐Holocene, although C3 vegetation is still dominant. Statistically significant negative correlations between the δ13C data and Fet/Fed ratios suggest that continuous weakening of the EASM since the mid‐Holocene may be responsible for the 13C‐enrichment of the sediments in the Songnen grasslands. Field vegetation surveys, modern topsoil phytoliths, and δ13C calibration data indicate that the expansion of C4 species since the mid‐Holocene is mainly due to their ability to cope with aridity when growing season temperature is not undergoing a significant decrease. Future precipitation decreases in arid and semi‐arid lands should make C4 species more competitive in the grasslands of Northeastern China. This article is protected by copyright. All rights reserved.

22833. 题目: Soil DOC release and aggregate disruption mediate rhizosphere priming effect on soil C decomposition
文章编号: N20031805
期刊: Soil Biology and Biochemistry
作者: Yanghui He, Weixin Cheng, Lingyan Zhou, Junjiong Shao, Huiying Liu, Huimin Zhou, Kai Zhu, Xuhui Zhou
更新时间: 2020-03-18
摘要: Roots and the associated rhizospheric activities regulate the mineralization of native soil organic matter (SOM), which is referred to as the rhizosphere priming effect (RPE). Although the importance of RPE for carbon cycle has increasingly been recognized, experimental evidence for how soil structural changes modulate the RPE is still unavailable. We addressed this issue by growing soybean plants (C3) in a C4-derived soil in a continuous 13C- labeling greenhouse. We hypothesized that root-induced soil structural change regulated the RPE by destabilizing soil matrix-protected organic carbon. Our results showed that the RPE was tightly coupled with plant photosynthetic activity, the disruption of coarse macro-aggregates, and the increased release of dissolved organic carbon (DOC) from the soil matrix. These findings indicate that living roots together with rhizodeposits not only can directly stimulate rhizospheric microbial activities, but also can make soil matrix-protected organic carbon available to microbial attacks and further enhance the RPE. This study suggests that the RPE on SOM mineralization is intimately linked with the dynamics of soil structures and DOC, which should be considered in future studies on mechanistic understanding and modeling of the RPE.

22834. 题目: Spatiotemporal variations of DOM components in the Kushiro River impacted by a wetland
文章编号: N20031804
期刊: Environmental Science and Pollution Research
作者: Md. Shafiquzzaman, Husnain Haider, Muhammed A. Bhuiyan, Abdelkader T. Ahmed, Saleem S. AlSaleem, Abdul Razzaq Ghumman
更新时间: 2020-03-18
摘要: Dissolved organic matter (DOM) has been recognized as a serious water quality problem in natural water bodies receiving pollution loads from point and nonpoint sources. The present study investigates the spatiotemporal variability of DOM composition in the Kushiro River and its tributaries (Eastern Hokkaido, Japan) impacted by the Kushiro wetland. Water samples were collected in the wet and dry seasons from several locations of the river and analyzed for DOM characteristics by UV–visible and excitation–emission matrix fluorescence spectroscopy techniques and by developing water quality index. Rather than the spatial effect, significant seasonal impacts on DOM pollution in the Kushiro River were observed. Overall concentrations of DOM decreased during the dry season. The increase of specific ultraviolet absorbance in the dry season indicated an increasing trend of humification, aromaticity and molecular weight of DOM. Five fluorescent peaks, including peaks A, C, M, B, and T were predicted by EEM spectra. Peaks A and C were found to be the most dominating peaks in both the seasons and indicated enrichment of humic-like matters in river water. The intensities of poly-aromatic humic substances as well as DOM components of microbial origin increase in the wet season and proteins like autochthonous DOM increase during the dry season. The study recognized the contribution of freshly produced DOM component by the decomposition of wetland plants in wet season and effect of snowfall in the dry season. Analysis of three fluorescence indices revealed that the river water primarily contains terrestrially dominated DOM. A significant impact of the adjacent WWTPs and wetland to the river water DOM were also observed. The water quality index of river water DOM showed low to medium levels of DOM pollution in the Kushiro River.

22835. 题目: Removal of methylene blue dye using rice husk, cow dung and sludge biochar: characterization, application, and kinetic studies
文章编号: N20031803
期刊: Bioresource Technology
作者: Anees Ahmad, Nawaz Khan, Balendu Shekher Giri, Pankaj Chowdhary, Preeti Chaturvedi
更新时间: 2020-03-18
摘要: The present studies aimed for the removal of Methylene blue (MB) dye using the rice husk biochar (RHB), cow dung biochar (CDB) and domestic sludge biochar (SB) synthesized through slow pyrolysis at 500°C. The biochar was used for the adsorption of synthetic aqueous MB dye. The removal efficiencies of MB by CDB, RHB and SB in a batch experiment were 97.0-99.0; 71.0-99.0 and 73.0-98.9 % at conditions, pH (2.0–11.0); Biochar dosage (0.5–6.0 g/100mL) for 5 days. Adsorption isotherm of Langmuir constant (KL) were obtained 0.101, 0.583 and 0.128 for RHB, CDB and SB respectively. Further, adsorption kinetics of pseudo first order for RHB, CDB and SB were 0.068, 0.018, and 0.066 while it was 0.031, 0.023 and 0.273 for pseudo second order kinetics. Thus, CDB was more effective adsorbent for the dye removal. The pHz values were 7.8, 6.3 and 6.0 for the CDB, RHB, and SB, respectively.

22836. 题目: A lignin-biochar with high oxygen-containing groups for adsorbing lead ion prepared by simultaneous oxidization and carbonization
文章编号: N20031802
期刊: Bioresource Technology
作者: Yuan Li, Fei Wang, Yaowen Miao, Yuliang Mai, Huanling Li, Xiaotian Chen, Jiazhi Chen
更新时间: 2020-03-18
摘要: A lignin-biochar with high acidic oxygen-containing groups was produced via a facile simultaneous oxidization and carbonization of pulping lignin by using sulfuric acid for the first time. The lignin-biochars were investigated by 13C NMR, FTIR and XPS, and results demonstrated that treatment by sulfuric acid could oxidize part of aromatic ring side chain to introduce high acidic oxygen-containing group, especially carboxyl group,. Their total acidic oxygen-containing groups of lignin-biochar including –COOH and Ar-OH reached 8.64 mmol/g. Adsorption experiments were carried and the maximum adsorption capacity of lignin-biochar for Pb2+ reached 679 mg/g, which was significantly higher than other lignin-based or carbon adsorbents. Moreover, it could maintain high removal rate at high adsorption capacity. It also demonstrated that adsorption capability was proportional to the accessible carboxyl groups.

22837. 题目: Implication for adsorption and degradation of dyes by Humic acid: light driven of Environmentally persistent free radicals to activate reactive oxygen species
文章编号: N20031801
期刊: Bioresource Technology
作者: Yanzhuo Zhang, Muchen Yin, Xuedi Sun, Jing Zhao
更新时间: 2020-03-18
摘要: Humic acid (HA) was applied as the biosorbent for the adsorption and degradation of dyes in the presence of environmentally persistent free radicals (EPFRs). Scanning Electron Microscope (SEM) analysis showed that the microstructure of the HA surface and the thermal stability was analyzed by thermogravimetric analysis (TGA). Following irradiation, semiquinone EPFRs (g-factor>2.0045) were generated on the HA surface. Both O2 and the addition of H2O2 were able to promote the generation of hydroxyl and superoxide radicals for the degradation of dye in aqueous solution. Furthermore, adsorption was observed to remove large amounts of the dyes, while the instantaneous free radical degradation process reduced the dyes to the lower concentration. In addition, a linear relationship was observed between the consumption of EPFRs and dye degradation rates. In ternary systems, HA conformed to Langmuir (476.19-1250.12 mg/L) and pseudo-second-order kinetic models. This work offers new insights into HA-EPFRs and their potential applications.

22838. 题目: Formation and control of bromate in sulfate radical-based oxidation processes for the treatment of waters containing bromide: A critical review
文章编号: N20031705
期刊: Water Research
作者: Chaoting Guan, Jin Jiang, Suyan Pang, Yang Zhou, Yuan Gao, Juan Li, Zhen Wang
更新时间: 2020-03-17
摘要: Sulfate radical-based advanced oxidation processes (SR-AOPs) show a good prospect for effective elimination of organic contaminants in water due to the powerful oxidation capability and good adaptability of sulfate radical (SO4•−). However, great concerns have been raised on occurrence of the carcinogenic byproduct bromate (BrO3−) in SR-AOPs. The present article aims to provide a critical review on BrO3− formation during bromine (Br)-containing water oxidation by various SR-AOPs. Potential reaction mechanisms are elaborated, mainly involving the sequential oxidation of bromide (Br−) by SO4•− to Br-containing radicals (e.g., bromine atom (Br•)) and then to hypobromous acid/hypobromite (HOBr/OBr−), which acts as the requisite intermediate for BrO3− formation. Some key influencing factors on BrO3− formation are discussed. Particularly, dissolved organic matter (DOM) as a component ubiquitously present in aquatic environments shows a significant suppression effect on BrO3− formation, primarily attributed to the reduction of Br• by DOM to Br−. The reaction of Br• with DOM can hardly produce organic brominated byproducts, while their formation is mainly due to the bromination of HOBr/OBr− generated through nonradical pathways such as the direct reaction of Br− with oxidants (e.g., peroxymonosulfate (PMS)) or other reactive species derived from catalytic activators (e.g., Co(III) in the Co(II)/PMS process). The debromination of brominated pollutants during their oxidation by SO4•− results in the release of Br−, which, however, is not further transformed to BrO3− until coexisting organic matters are mineralized nearly completely. Furthermore, possible strategies for control of BrO3− formation in SR-AOPs as well as the future research needs are proposed.

22839. 题目: Solvent-free synthesis of magnetic biochar and activated carbon through ball-mill extrusion with Fe3O4 nanoparticles for enhancing adsorption of methylene blue
文章编号: N20031704
期刊: Science of The Total Environment
作者: Yanfei Li, Andrew R. Zimmerman, Feng He, Jianjun Chen, Lujia Han, Hao Chen, Xin Hu, Bin Gao
更新时间: 2020-03-17
摘要: Magnetic carbonaceous adsorbents were synthesized by ball-milling biochar (BC) or activated carbon (AC) with Fe3O4 nanoparticles, and their capacities to sorb methylene blue (MB) from water were evaluated and compared. Ball milling with magnetite not only improved the surface properties of the carbonaceous adsorbents, especially BC, but also introduced magnetic properties through mechanical extrusion. Furthermore, ball-mill extrusion increased the MB adsorption capacity of BC at all pH values by 14-fold, on average, but BC ball milled with magnetite had even greater MB adsorption capacity (27-fold, greater, on average). While ball milling of AC also improved its MB adsorption capacity (by almost 3-fold, on average), ball milling with magnetite did not further improve its MB adsorption capacity. All the magnetic adsorbents showed fast MB adsorption kinetics, reaching equilibrium within about 8 h. The Langmuir maximum MB adsorption capacity of the magnetic ball-milled BC (MBM-BC) was the highest (500.5 mg/g) among all the samples including the ones derived from AC. After five adsorption-desorption cycles, MBM-BC maintained about 80% MB removal capacity. The high MB adsorption capacity of MBM-BC was attributed to its increased surface area, opened pore structure, functional groups and aromatic CC bonds, which promoted π-π and electrostatic interactions. Findings from this study indicate that the magnetic ball-milled BC is a promising adsorbent due to its environmentally friendly synthesis, high efficiency, low cost, and convenience in operation.

22840. 题目: Alpine Hummocks Drive Plant Diversity and Soil Fertile Islands on the Tibetan Plateau
文章编号: N20031703
期刊: Wetlands
作者: Hui Zhao, Da Wei, Yan Yan, Jianbo Wu, Xiaodan Wang
更新时间: 2020-03-17
摘要: Earth hummocks are widely distributed in arctic, sub-Arctic and alpine regions and have important roles in determining plant diversity and the nutrient content of soils. We investigated the impact of the spatial heterogeneity on soil properties and plant communities caused by the hummocks on the Tibetan Plateau. The results indicated alpine hummocks created higher plant diversity and soil fertile island patterns under Kobresia Genus communities. Vegetation height, cover, above-ground and underground biomass, species richness and diversity at the top of well-developed hummocks were the significantly higher than those in the inter-hummocks and surrounding flat ground. The soil organic carbon content in surface soil layer (0-50 cm) at the hummock top was 154.6% and 172.3% higher than those in inter-hummock area and the flat ground, respectively. From the developing to well-developed stage, K. littledalei became the dominant population at hummock top instead of K. humilis, and fertile islands gradually formed with higher soil organic carbon and total nitrogen, lower soil moisture and wider soil temperature variation RDA analysis further indicated the interactions of plant community succession and soil fertile island could create positive feedbacks to nutrient-rich patches.