221. 题目: Thermally regenerable FeS/N-doped biochar catalyzed peroxydisulfate oxidative destruction of aqueous triclosan
Ferrous sulfide loaded on N-doped biochar (FeS/NBC) was prepared to pyrolyze jute fibers pretreated with (NH4)2Fe(SO4)2. FeS/NBC-catalyzed degradation of triclosan was assessed by peroxydisulfate oxidation. The effects of solution pH, foreign anions and peroxydisulfate concentration were investigated. It is found that neutral pH was conducive to removal of triclosan, achieving about 99% triclosan removal and 65% mineralization level. The presence of HCO3− and HPO42− will inhibit triclosan degradation, but Cl− showed a considerable promotion. Importantly, the spent FeS/NBC catalyst can be regenerated via a reheat treatment to completely recover the catalytic activity. Electron paramagnetic resonance and quenching experiments demonstrated that radicals (•OH, •SO4− •O2−) and non-radical (1O2) were the major reactive species in the reaction. GC-MS analysis identified that the residual intermediates from cycloaddition and ether bond breakage existed in the reaction solution, and recommended radical-dominated and singlet oxygen-assisted degradation pathways. The evaluation of actual samples showed that the presence of Cl− could enhance the removal of triclosan, and the generation of chlorine-based radicals was suggested as the main reason for this result. This study proved FeS/NBC-PDS system could efficiently remove triclosan in water, and the catalyst can be regenerated by a simple reheat treatment.
222. 题目: The impact of inorganic ions on the solar photolysis of chlorinated dissolved organic matter from different sources: spectral characteristics, disinfection byproducts, and biotoxicities
Dissolved organic matter (DOM) from wastewater treatment plant (WWTP) effluent is chlorinated and then discharged into natural waters, where it is subject to solar irradiation. However, the impacts of inorganic ions in natural waters on the photochemical transformations of the chlorinated DOM (DOM-Cl) have not been studied comprehensively. In this study, variations in the spectral characteristics, disinfection byproducts (DBPs), and biotoxicities of DOM-Cl under solar irradiation at different pH values and in the presence of NO and HCO were revealed. Three sources of DOM, including DOM from a WWTP effluent, natural organic matter from the Suwannee River, and DOM from plant leaf leachate, were investigated. Solar irradiation resulted in the oxidation of the highly reactive aromatic structures and then reduced the amounts of chromophoric and fluorescent DOM, especially under alkaline conditions. Moreover, alkaline conditions significantly promoted the detected DBPs degradation and the biotoxicities attenuation, while NO and HCO generally impeded them (or did not work). Dehalogenation of the unknown halogenated DBPs and photolysis of the nonhalogenated organics were the main mechanisms for the DOM-Cl biotoxicity reductions. Hence, improving the ecological safety of WWTP effluents could be achieved through solar irradiation by removing the DBPs formed.
223. 题目: Novel sludge-sugarcane bagasse mixed biochar as an efficient activator for peroxymonosulfate to degrade bisphenol AF
The exploitation of cost-effective and environmentally friendly biochar catalysts is of major importance for the oxidative treatment of toxic organic wastewater and the resource utilization of waste biomass. In this work, sewage sludge and bagasse waste were co-pyrolyzed into a novel biochar catalyst (SB-BC-900) for efficiently activating peroxymonosulfate (PMS) to degrade bisphenol AF (BPAF) in wastewater. Compared with single sludge biochar (S-BC-900), SB-BC-900 had a larger cumulative pore volume, more oxygenated functional groups (OFGs) and higher graphitization degree, with a significantly higher catalytic capacity. SB-BC-900 enabled rapid degradation of BPAF within 10 min at a low PMS dosage (molar ratio [PMS]: [BPAF] = 2.67:1). There was mainly the non-free radical pathway dominated by singlet oxygen (1O2) in the SB-BC-900/PMS system. Graphitic carbon (sp2 C=C) and OFGs on SB-BC-900 played a crucial part in the catalytic degradation of BPAF. A green approach is provided to resource waste biomass for efficient wastewater treatment in this work.
224. 题目: Spatiotemporal response of dissolved organic matter diversity to natural and anthropogenic forces along the whole mainstream of the Yangtze River
The Yangtze River, the largest river in Asia, plays a crucial role in linking continental and oceanic ecosystems. However, the impact of natural and anthropogenic disturbances on composition and transformation of dissolved organic matter (DOM) during long-distance transport and seasonal cycle is not fully understood. By using a combination of elemental, isotopic and optical techniques, as well as Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR MS), we investigated DOM abundance and composition along the whole mainstream at highly spatial resolution in the dry and early wet seasons. Our findings showed that the concentration and flux of dissolved organic carbon (DOC) in the Yangtze River was much lower compared with other worldwide larger rivers. The distribution of δ13CDOC and higher abundance of humic-like fluorescent component and highly unsaturated and phenolics (HUPs) compound reflected a prominent contribution of allochthonous DOM. Further optical and molecular analysis revealed humic-like fluorescent components were coupled with CHO molecules and HUPs compound with higher aromatic, unsaturated, molecular weight and stable characteristics between upstream and midstream reaches. With increasing agricultural and urban land downstream, there were more heteroatomic formulae and labile aliphatic and protein-like compounds which were derived from human activities and in situ primary production. Meanwhile, DOM gradually accumulates with slow water flow and additional autochthonous organics. Weaker solar radiation and water dilution during the dry/cold season favours highly aromatic, unsaturated and oxygenated DOM compositions. Conversely, higher discharge during the wet/warm season diluted the terrestrial DOM, but warm temperatures could promote phytoplankton growth that releases labile aliphatic and protein-like DOM. Besides, chemical sulfurization, hydrogenation and oxygenation were found during molecular cycling processes. Our research emphasizes the active response of riverine DOM to natural and anthropogenic controls, and provides a valuable preliminary background to better understand the biogeochemical cycling of DOM in a larger river.
225. 题目: Black carbon pollution in China from 2001 to 2019: Patterns, trends, and drivers
Based on a near real–time 10 km × 10 km resolution black carbon (BC) concentration dataset, this study investigated the spatial patterns, trend variations, and drivers of BC concentrations in China from 2001 to 2019 with spatial analysis, trend analysis, hotspot clustering, and multiscale geographically weighted regression (MGWR). The results indicate that Beijing–Tianjin–Hebei, the Chengdu–Chongqing agglomeration, Pearl River Delta, and East China Plain were the hotspot centers of BC concentration in China. From 2001 to 2019, the average rate of decline in BC concentrations across China was 0.36 μg/m3/year (p < 0.001), with BC concentrations peaking around 2006 and sustaining a decline for the next decade or so. The rate of BC decline was higher in Central, North, and East China than in other regions. The MGWR model revealed the spatial heterogeneity of the influences of different drivers. A number of enterprises had significant effects on BC in East, North, and Southwest China; coal production had strong effects on BC in Southwest and East China; electricity consumption had better effects on BC in Northeast, Northwest, and East China than in other regions; the ratio of secondary industries had the greatest effects on BC in North and Southwest China; and CO2 emissions had the strongest effects on BC in East and North China. Meanwhile, the reduction of BC emissions from the industrial sector was the dominant factor in the decrease of BC concentration in China. These findings provide references and policy prescriptions for how cities in different regions can reduce BC emissions.
226. 题目: Effects of varying amounts of different biochars on mercury methylation in paddy soils and methylmercury accumulation in rice (Oryza sativa L.)
There is growing evidence for the potential of biochars (BCs) in remediating mercury-contaminated paddy soils, but the high doses commonly used in laboratory studies discourage BC application in practice. To address these difficulties, we compared the effects of varying amounts of BCs from different sources on the formation of methylmercury (MeHg) in soil and its accumulation in rice through microcosm and pot experiments. The addition of a wide range of added doses (0.3, 0.6, 1, 2, 4 and 5 %, w/w) of BCs derived from different biomass feedstocks (i.e., corn stalk, wheat straw, bamboo, oak and poplar) significantly decreased the fraction of ammonium thiosulfate ((NH4)2S2O3)-extractable MeHg in the soil, although the MeHg contents varied with BC types and doses during soil incubation. However, the extractable MeHg in the soil did not continuously decrease with increasing BC doses, especially at doses of >1 %, resulting in limited further reductions. Moreover, a relatively low application rate (0.3–0.6 %, w/w) of BCs (i.e., corn stalk, wheat straw and bamboo-derived BC), especially of bamboo-derived BCs, significantly decreased the MeHg levels (42–76 %) in rice grains (brown rice). Meanwhile, the extractable soil MeHg decreased (57–85 %), although the MeHg in the soil varied under BC amendment during rice cultivation. These results provide further evidence that applying BC produced from different raw carbon materials (e.g., lignocellulosic biomass) could effectively reduce MeHg accumulation in rice grains, possibly due to MeHg bioavailability reduction in the soil. Our results suggest the possibility of mitigating MeHg accumulation in rice with a low dose of BCs, with great potential for use in remediating moderately contaminated paddy soils.
227. 题目: The adsorption mechanism of sludge-based biochar toward highly concentrated organic membrane concentrates from landfill leachate
In this study, the sludge-based biochar (BC) was prepared by dewatered sludge from a membrane bioreactor to treat the membrane concentrate. Then, the adsorbed and saturated BC was regenerated (RBC) by pyrolysis and deashing treatment to further treat the membrane concentrate. Afterward, the composition of membrane concentrate before and after BC or RBC treatment was detected, and the biochars’ surface characteristics were characterized. The results showed that RBC outperformed BC in the abatement of chemical oxygen demand (CODCr), ammonia nitrogen (NH3-N), and total nitrogen (TN), with their removal rates of 60.07%, 51.55%, and 66.00%, respectively, an improvement of 9.49%, 9.00% and 16.50% of the removal rate compare to BC. The specific surface area of BC and RBC was about 109 times as much as the original dewatered sludge, and the pore size of BC and RBC belonged to mesopore which was a benefit for removing small and mediate size pollutants. The increase of the oxygen-containing functional group in RBC and the ash abatement contributed much to the improvement of RBC adsorption performance. In addition, cost analysis showed that BC+RBC had a cost of 0.76$/kg for COD removal, which was a lower cost than other common membrane concentrate treatment technologies.
228. 题目: Effects of returning corn straw incorporated with fungi, and fermented corn straw on soil humic acid structural characteristics
During our previous laboratory incubation experiments, we found that the fungus (Trichoderma reesei (T. reesei)) has the best ability to transform corn straw into humic acid-like (HAL) substance. To further investigate whether the direct application of corn straw incorporated with T. reesei is as effective as the application of corn straw fermented with T. reesei in promoting the transformation and accumulation of stable soil organic matter components, a 720-day field experiment was established.
The field experiment involved four treatments applied to the soil at equal carbon mass: corn straw incorporated with T. reesei (CS-T), corn straw (CS), fermented corn straw treated by T. reesei (FCS-T), and blank control treatment (CK). The elemental analyzer, fluorescence and Fourier transform infrared spectroscopy, and thermogravimetric were used to comprehensively characterize the soil humic acid (HA) structure of the above treatments.
The results showed that the CS-T treatment encouraged the decomposition of unstable components of soil HA at 30 days, and formed a relatively younger HA at 180 days. The FCS-T treatment directly formed soil HA with more aliphatic compounds between 30 and 360 days. After a long transformation and accumulation, the FCS-T treatment at 720 days increased the relative HA content to 29.3% and formed more aromatic and stable HA with the H/C ratio and fluorescence index of 1.257 and 0.618, respectively.
The application of FCS-T could be a more suitable practice than the direct application of corn straw to increase soil HA content and aromaticity, as well as to improve soil HA stability.
229. 题目: Factors affecting soil organic carbon pool in marshes along the Yarlung Zangbo River, Tibet China
230. 题目: Preparation of activated biochar with adjustable pore structure by hydrothermal carbonization for efficient adsorption of VOCs and its practical application prospects
Porous-activated biochars with abundant pores have great potential for the treatment of volatile organic compounds (VOCs). However, the lack of cost-effective pore-modulation methods for these materials has hindered their feasibility for large-scale use as adsorbents. In this study, hydrothermal carbonization (HTC) of glucose, the basic unit of cellulose, was investigated, and the pore structure of the obtained hydrochar was precisely determined by controlling the main factors of the hydrothermal process. Orthogonal experiments were conducted to determine the most suitable conditions for a hierarchical porous structure, and the water ratio was considered the main regulating factor. The range of possible carbon precursors was extended to all biomasses by proposing an innovative model to explain the formation of pore structures during the conversion of basic biomass components to biochar in the HTC process. The results revealed that the water ratio significantly affected the decomposition and carbonization of biomass in HTC, which further affected the microdomain unit size and, thus, the biochar pore structure. Further, the graded porous structure substantially enhanced the biochar adsorption capacity. HTC was found to have a greater potential for practical applications, as it presented a substantially higher yield, compared to direct carbonization processes. Overall, this work provides guidance and an effective reference for the pore size adjustment of porous-activated biochar developed for the adsorption of pollutants.
Data will be made available on request.
231. 题目: Enhanced simultaneous arsenite oxidation and sorption by Mn-modified biochar: Insight into the mechanisms under optimal modification condition
This study successfully prepared two types of Mn-modified biochar using chemical co-precipitation (MBC1) and impregnation pyrolysis methods (MBC2) for simultaneous oxidation and adsorption of arsenic species efficiently. Both Mn-modified biochars were able to remove significantly greater quantities of As(Ⅲ) from solution than the pristine biochar. Among them, MBC1 showed better oxidation and adsorption capacity, especially at a pyrolysis temperature of 600 °C and a ratio of 3:10 (MnOx: BC). The As(Ⅲ) adsorption on MBC1 conformed to the pseudo-second-order kinetics and Freundlich isothermal models. The maximum adsorption capacity of MBC1 for As(Ⅲ) at pH 7.0 calculated from the Langmuir adsorption isotherm was 32.06 mg·g-1. The related mechanisms were characterized using elemental analysis, SEM, BET, FTIR, XRD, XPS and HPLC-ICP-MS techniques. Results showed that Mn-oxides significantly improved the surface physicochemical properties of biochar, with significant increase of functional groups (e.g., hydroxyl and carboxyl), the specific surface area and pore structure, which not only promoted the adsorption of arsenic species but mitigated the passivation of biochar surface and Mn-oxides by Mn(Ⅱ). The oxidation of As(Ⅲ) via Mn(Ⅲ) and Mn(Ⅳ) in Mn-oxides on the modified biochar subsequently resulted in more efficient production of As(Ⅴ). The Mn(Ⅱ) and As(Ⅴ) could subsequently precipitate and be re-adsorbed on the biochar surface. The re-adsorbed Mn(Ⅱ) increased the positive charge on the biochar surface, and the strong electrostatic attraction can promote As(Ⅴ) adsorption at pH < pHPZC. This study further revealed the favorable conditions and underlying mechanisms for the enhanced simultaneous arsenite oxidation and sorption by Mn-modified biochar.
232. 题目: Increasing tree productivity does not translate into greater soil organic carbon storage
Increasing soil organic carbon (SOC) storage is one of the promising solutions to mitigate climate change. Fast-growing trees are a potential tool in this context as they rapidly accumulate C in their biomass and could transfer more organic matter (OM) into the soil. However, the relationship between aboveground productivity and SOC storage remains poorly understood. Five clones with different growth rates were selected from a 14-year-old hybrid poplar plantation located in New Liskeard, ON, Canada. We collected soil cores at 87.5 and 175.0 cm distance from the stem and at 0–20, 20–40 and 40–60 cm soil depth for soil C concentration analysis. The most productive clone DN2 (Populus deltoides × P. nigra) stored less SOC (83 Mg ha−1) between 0 and 60 cm depth than the mid-productive clones 1079 (Populus × jackii (P. balsamifera × P. deltoides)) and 915005 (P. maximowiczii × P. balsamifera) (95 and 96 Mg ha−1 respectively), while the least productive clone 747210 (P. balsamifera × P. trichocarpa) also had a lower SOC stock (85 Mg ha−1) compared to the other clones, but not significantly. There was no relationship between aboveground productivity and SOC stocks and total SOC stocks increased by 6 % when the sampling distance was closer to the tree stems. The difference in SOC stocks between clones was mostly observed at the 20–40 cm depth suggesting the significant effect of roots on SOC storage. Soil C/N ratios were significantly different between clones at 0–20 and 20–40 cm depths suggesting differences in OM decomposition rates between clones. There could be a trade-off between aboveground productivity and litter decomposition rate to increase SOC storage.
233. 题目: Transformations of Ferrihydrite–Extracellular Polymeric Substance Coprecipitates Driven by Dissolved Sulfide: Interrelated Effects of Carbon and Sulfur Loadings
234. 题目: Co-composting poultry carcasses with wood-based, distillers’ grain and cow manure biochar to increase core compost temperatures and reduce leachate's COD
Composting has been recognized as a viable method to dispose of animal carcasses. Common concerns related to the composting process include low core temperatures, leachate generation, and ammonia emissions. This study tested co-composting full-size poultry carcasses with commercially available biochars at an aeration rate of 0.8 L∙min−1. Biochars prepared by gasifying wood pallets, distillers’ grains, and cow manure were added to the composting bins at the 13% rate (by volume). Results showed that poultry carcasses with wood-based and cow manure biochar increased temperatures by 2.0 to 3.3 °C. All biochar-amended bins met the time–temperature criteria to eliminate avian influenza (H7N1) viruses, which could not be achieved without biochar addition. Wood-based biochar amendment lowered the cumulative chemical oxygen demand of the leachate samples by 87% (P = 0.02). At the rate studied, the biochar amendment did not significantly affect ammonia emissions (P = 0.56). BET surface area of wood-based biochar was 1.4 and 28 times greater than that of cow manure and distillers’ grain biochar, respectively. Compared to no biochar addition, wood-based biochar resulted in significantly higher compost temperatures (P = 0.02), lower leachate COD values (P = 0.02), and a higher total nitrogen content (P = 0.01) while it did not cause an increase in sodium content (P = 0.94) of the finished compost. In conclusion, amending the poultry carcass composting process with wood-based biochar (13% by volume) is recommended, especially to eliminate disease-causing agents.
235. 题目: Quantifying blue carbon stocks and the role of protected areas to conserve coastal wetlands
Vegetated coastal ecosystems, in particular mangroves, tidal marshes and seagrasses are highly efficient at sequestering and storing carbon, making them valuable assets for climate change mitigation and adaptation. The state of Queensland, in northeastern Australia, contains almost half of the total area of these blue carbon ecosystems in the country, yet there are few detailed regional or state-wide assessments of their total sedimentary organic carbon (SOC) stocks. We compiled existing SOC data and used boosted regression tree models to evaluate the influence of environmental variables in explaining the variability in SOC stocks, and to produce spatially explicit blue carbon estimates. The final models explained 75 % (for mangroves and tidal marshes) and 65 % (for seagrasses) of the variability in SOC stocks. Total SOC stocks in the state of Queensland were estimated at 569 ± 98 Tg C (173 ± 32 Tg C, 232 ± 50 Tg C, and 164 ± 16 Tg C from mangroves, tidal marshes and seagrasses, respectively). Regional predictions for each of Queensland's eleven Natural Resource Management regions revealed that 60 % of the state's SOC stocks occurred within three regions (Cape York, Torres Strait and Southern Gulf Natural Resource Management regions) due to a combination of high values of SOC stocks and large areas of coastal wetlands. Protected areas in Queensland play an important role in conserving SOC assets in Queensland's coastal wetlands. For example, ~19 Tg C within terrestrial protected areas, ~27 Tg C within marine protected areas and ~ 40 Tg C within areas of matters of State Environmental Significance. Using multi-decadal (1987–2020) mapped distributions of mangroves in Queensland; we found that mangrove area increased by approximately 30,000 ha from 1987 to 2020, which led to temporal fluctuations in mangrove plant and SOC stocks. We estimated that plant stocks decreased from ~45 Tg C in 1987 to ~34.2 Tg C in 2020, while SOC stocks remained relatively constant from ~107.9 Tg C in 1987 to 108.0 Tg C in 2020. Considering the level of current protection, emissions from mangrove deforestation are potentially very low; therefore, representing minor opportunities for mangrove blue carbon projects in the region. Our study provides much needed information on current trends in carbon stocks and their conservation in Queensland's coastal wetlands, while also contributing to guide future management actions, including blue carbon restoration projects.
236. 题目: Advancement of biochar-aided with iron chloride for contamination removal in wastewater and biogas production: A review
The use of fossil fuels, emission of greenhouse gases (GHG) into the atmosphere, and waste pose a problem to the environment and public health that urgently needs to be dealt with. Among numerous chemical activating agents that can be added to anaerobic digestion (AD) to enhance nutrient removal and increase the quality and quantity of biomethane, iron chloride (FeCl3) is the one that has the lowest cost and is the most environmentally friendly. This state-of-the-art review aims to revise the influence of FeCl3 on the Brunauer–Emmett–Teller (BET) surface area of biochar and its ability to increase methane (CH4) yield and remove contaminants from biogas and wastewater. The novelty of the study is that FeCl3, an activating agent, can increase the BET surface area of biochar, and its efficacy increases when combined with zinc chloride or phosphoric acid. Regarding the removal of contaminants from wastewater and biogas, FeCl3 has proven to be an effective coagulant, reducing the chemical oxygen demand (COD) of wastewater and hydrogen sulfide in biogas. The performance of FeCl3 depends on the dosage, pH, and feedstock used. Therefore, FeCl3 can increase the BET surface area of biochar and CH4 yield and remove contaminants from wastewater and biogas. More research is needed to investigate the ability of FeCl3 to remove water vapor and carbon dioxide during biogas production while accounting for a set of other parameters, including FeCl3 size.
237. 题目: The mobility and fate of Cr during aging of ferrihydrite and ferrihydrite organominerals
The fixation of environmentally hazardous Cr(VI) in soils is largely attributed to its retention by iron (Fe) (oxyhydr)oxides in the soil environment, which are prevailingly associated with organic carbon (OC). The effect of OC with different binding strengths on Cr(VI) adsorption and the mobility and fate of Cr(VI) during aging of Fe (oxyhydr)oxide however, are unknown. Here we investigate how OC binding strength influences Cr(VI) adsorption to ferrihydrite (Fh) organominerals, the aging of Fh organominerals and the subsequent retention or release of Cr(VI) as aging proceeds. We conduct Cr(VI) adsorption experiments onto Fh organominerals, apply surface complexation modelling to study the relative binding strengths between OC and Cr(VI), and then conduct aging experiments to track the redistribution of Cr(VI). We show based on the relative binding strength between OC and Cr(VI), that weakly-bound OC at different C loadings has almost no discernable influence on Cr(VI) adsorption, while strongly-bound OC significantly suppresses Cr(VI) adsorption via surface site blocking and/or electrostatic repulsion. The mobility and fate of Cr(VI) with Fh organominerals during the aging process is strongly influenced by the presence of OC. Weakly-bound carboxyl-poor OC not only near doubles the rate of Cr(VI) retained (i.e., Cr(VI) redistribution from a weakly-bound to a strongly-bound fraction) in neoformed Fe minerals at pH 5.0, but also increases the final proportion of Cr(VI)strongly-bound, which we attribute to the loose and porous structure of Fh organominerals and easier replacement of weakly-bound OC by Cr(VI). More strongly-bound carboxyl-rich OC and higher pH however, reduces the influence of OC, such that the rate of Cr(VI) retained is similar to or lower than that for the pure Fh system, which we attribute to the fact that the strongly-bound OC is less easily replaced by Cr(VI) and hence Cr(VI) is less able to access surface sites or surface pores and thus to be retained inside neoformed minerals. Overall we suggest that OC with higher carboxyl-richness will further suppress the rate of Cr(VI) retained and overall proportion of Cr(VI)strongly-bound, and thus that the mobility and fate of Cr(VI) in soils is strongly controlled by the carboxyl-richness of OC in Fe organominerals.
238. 题目: Long-term tillage and irrigation effects on aggregation and soil organic carbon stabilization mechanisms
Sustainable soil management practices are required in agriculture to enhance carbon sequestration and restore soil functions. Here, the aim was to investigate the effect of different tillage practices combined with or without irrigation on (i) soil organic carbon (SOC) content, (ii) fungal biomass and their relationships with aggregate size classes in the soil surface layer; further, (iii) the concept of soil particle saturation with SOC was tested to evaluate if a threshold was reached in a 14 year-experiment. Our hypothesis was that long-term irrigation, intensive tillage and their combination, would negatively affect soil aggregation and SOC stabilization. The experiment has started in 2003 on a research farm in Canterbury, New Zealand. The present work focused on two contrasting tillage practices –intensive tillage with 20–25 cm ploughing (IT) and direct drill (DD)– combined with sprinkler-irrigated and non-irrigated (hereafter called Rainfed) conditions in a split-plot experimental design. Soil samples (0–5 cm layer) were analyzed for pore size distribution, specific surface area and microbial biomass. Further, wet sieving was used to isolate large macroaggregates (LM, > 2000 μm), small macroaggregates (SM, 250–2000 μm), microaggregates (m, 53–250 μm), particle sized silt + clay fractions (s+c, < 53 μm) and Fine20 particles (<20 μm), followed by the analysis of aggregate morphology and SOC quantification in them. Results showed that both DD and Rainfed management increased total SOC content of the bulk soil. Only the LM fraction and the SOC therein (OC-LM) increased significantly in DD compared to IT, while m and s+c fractions and OC-m and OC-s+c did not differ between treatments. Macroaggregate breakdown processes and measured SOC therein had likely not reached steady-state conditions, as suggested by the lack of any SOC differences in the aggregate size classes < 250 µm. In contrast, the Fines20:SOC ratio differentiated between soils that had reached (i.e., DD) or not reached (i.e., IT) the saturation threshold. Finally, it was observed that a higher fungal:bacteria (F:B) ratio was generally accompanied by a greater LM fraction and mean weight aggregate diameter, highlighting the importance of fungi in the formation of LM. These results suggested that our hypothesis of detrimental effects on soil aggregation and SOC accumulation of both tillage and irrigation was not fully demonstrated yet. A longer study period would be required to better understand the effects of such practices of SOC storage.
239. 题目: A Comparative Study in Black Carbon Concentration and its Emission Sources in Tribal Area
In this study, we have assessed the concentrations of black carbon (BC) measured using Aethalometer during different cooking periods in five different types of kitchens and different fuels in the tribal villages of east India. The BC mass concentrations were 397.24 ± 129.28, 403.49 ± 204.02, 463.45 ± 196.83, 458.77 ± 181.81 and 445.43 ± 193.67 µgm−3 for the indoor built kitchen (K1), indoor built kitchen but stoves situated in living area (K2), outside built kitchen (K3), semi-open kitchen (K4), and open cooking (K5), respectively. It is noted that the kitchen structure also significantly influences the accumulation of BC particles. During the whole study period, the maximum and minimum BC concentrations were 996.75 µg m−3 and 58.23 µg m−3, respectively. Maximum BC concentrations of 472.84 μgm−3 and minimum concentration of BC 402.11 μgm−3 were found on use of cow dung with paddy residue and wood as fuel, respectively. The result shows that the paddy residue emitted highest BC pollutants as compared to other fuel categories. We also studied the ambient BC concentration exposure for women living in villages. Despite no connection between study area and from industrial site, we observed a more tremendous amount of BC concentration. It shows that solid biomass fuel is responsible for increasing the concentrations level of BC in the atmosphere. The health risks were higher in K3 and K4 types of kitchens than in other types of kitchens. Our results indicate a requirement for a comprehensive study to thoroughly investigate the impact of household BC pollutants on the health risk assessments in the villages of east India.
240. 题目: Removal of NO at low concentration from air in urban built environments by activated miscanthus biochar
This work presents an innovative and sustainable approach to remove NO emissions from urban ambient air in confined areas (underground parking areas or tunnels) using low-cost activated carbons obtained from Miscanthus biochar (MSP700) by physical activation (with CO2 or steam) at temperatures ranging from 800 to 900 °C. The NO removal capacity of the activated biochars was evaluated under different conditions (temperature, humidity and oxygen concentration) and compared against a commercial activated carbon. This last material showed a clear dependence on oxygen concentration and temperature, exhibiting a maximum capacity of 72.6% in air at 20 °C, whilst, its capacity notably decreased at higher temperatures, revealing that physical NO adsorption is the limiting step for the commercial sample that presents limited oxygen surface functionalities. In contrast, MSP700-activated biochars reached nearly complete NO removal (99.9%) at all tested temperatures in air ambient. Those MSP700-derived carbons only required low oxygen concentration (4 vol%) in the gas stream to achieve the full NO removal at 20 °C. Moreover, they also showed an excellent performance in the presence of H2O, reaching NO removal higher than 96%. This remarkable activity results from the abundance of basic oxygenated surface groups, which act as active sites for NO/O2 adsorption, along with the presence of a homogeneous microporosity of 6 Å, which enables intimate contact between NO and O2. These features promote the oxidation of NO to NO2, which is further retained over the carbon surface. Therefore, the activated biochars studied here could be considered promising materials for the efficient removal of NO at low concentrations from air at moderate temperatures, thus closely approaching real-life conditions in confined spaces.