论文检索 |
|||||
|
总访问量：1121427次 总访客量：36852人 | |||||
| 关键词:... | |||||
| 期刊：... | |||||
所有论文 |
|||||
201. 题目: Synergy between graphitized biochar and goethite driving efficient H2O2 activation: Enhanced performance and mechanism analysis Due to the contradiction between attractive properties and undesirable Fenton-like catalytic performance of iron minerals, how to enhance their Fenton-like catalytic activity is a critical but challenging issue. Here, we took an eco-friendly approach to improve the Fenton-like catalytic capacity of goethite (α-FeOOH) by loading it on graphitized biochar (GBC), and the results indicated that the existence of GBC could successfully facilitate the oxytetracycline (OTC) removal. The degradation rate constant of α-FeOOH/GBC-10 composite was approximately 2.1 times higher than that of α-FeOOH. GBCs with different graphitization degrees were obtained by adjusting the pyrolysis temperature. Interestingly, the improvement of catalytic activity of α-FeOOH/GBC was well correlated with the graphitization degree of GBC, and the graphitized structures (sp2-C) and functional group (C=O) in GBC could expedite the blocked Fe(III)/Fe(II) cycling by speeding up the electrons transfer from H2O2 to α-FeOOH and donating electrons to Fe(III). In addition, the electron spin resonance and quenching experiments demonstrated that OTC removal was attributed to the joint action of •OH, O2•-, and 1O2. This study sheds light on the possible role of GBC in Fenton-like reactions based on iron minerals and thus, lays the groundwork for the rational construction of more efficient Fenton-like catalytic systems. | |||||
202. 题目: Experiment and multiscale molecular simulations on the Cu absorption by biochar-modified asphalt: An insight into removal capability and mechanism of heavy metals from stormwater runoff Asphalt has been the primary material for pavements and other building components such as roof shingles and waterproofing systems, which can be the path for stormwater runoff pollutants such as heavy metals (HMs). In this study, the capability and mechanism of asphalt and biochar-modified asphalt (BMA) to remove Cu as the typical HM found in the road dust and surface runoff were fundamentally explored for the first time. Experiment and multiscale molecular simulations were performed. Molecular dynamics (MD) simulations showed the Cu absorption into the asphalts. Monte Carlo (MC) and density functional theory (DFT) revealed the detailed mechanism of Cu absorption. Biochar (BC) presence modified the spatial distribution of maltenes and asphaltenes fractions in asphalt and enhanced the absorption. Maltenes were absorbed into the porous structure of BC, leaving more asphaltenes in the asphalt part of BMA. Asphaltenes were the Cu adsorbing preference sites ascribed to the cation-π interaction between Cu and the aromatic plane. The DFT simulations also suggested favourable adsorption of other commonly found metals (e.g., Cr, Pb, Ni, Cd, and Zn) onto asphaltenes. The present study found the capability and mechanism of BMA and asphalt to remove HMs at the molecular scales, providing a path for designing asphalts with value-added functionality in minimizing environmental pollution. | |||||
203. 题目: High oil content inhibits humification in food waste composting by affecting microbial community succession and organic matter degradation Composting is an effective technology to realize resource utilization of food waste in rural China. However, high oil content in food waste limits composting humification. This study investigated the effects of blended plant oil addition at different proportions (0, 10, 20, and 30%) on the humification of food waste composting. Oil addition at 10%–20% enhanced lignocellulose degradation by 16.6%–20.8% and promoted humus formation. In contrast, the high proportion of oil (30%) decreased the pH, increased the electrical conductivity, and reduced the seed germination index to 64.9%. High-throughput sequencing showed that high oil inhibited the growth and reproduction of bacteria (Bacillus, Fodinicurvataceae, and Methylococcaceae) and fungi (Aspergillus), attenuated their interaction, thus, reducing the conversion of organic matter, such as lignocellulose, fat, and total sugar, to humus, consequently leading to negative impacts on composting humification. The results can guide composting parameter optimization and improve effective management of rural food waste. | |||||
204. 题目: Bubbleless Air Shapes Biofilms and Facilitates Natural Organic Matter Transformation in Biological Activated Carbon | |||||
205. 题目: Sulfide inhibition on polyphosphate accumulating organisms and glycogen accumulating organisms: Cumulative inhibitory effect and recoverability Sulfate in wastewater can be reduced to sulfide and its impact on the stability of enhanced biological phosphorus removal (EBPR) is still unclear. In this study, the metabolic changes and subsequent recovery of polyphosphate accumulating organisms (PAOs) and glycogen accumulating organisms (GAOs) were investigated at different sulfide concentrations. The results showed that the metabolic activity of PAOs and GAOs was mainly related to H2S concentration. Under anaerobic conditions, the catabolism of PAOs and GAOs was promoted at H2S concentrations below 79 mg/L S and 271 mg/L S, respectively, and inhibited above these concentrations; whereas anabolism was consistently inhibited in the presence of H2S. The phosphorus (P) release was also pH-dependent due to the intracellular free Mg2+ efflux from PAOs. H2S was more destructive to the esterase activity and membrane permeability of PAOs than those of GAOs and prompted intracellular free Mg2+ efflux of PAOs, resulting in worse aerobic metabolism and subsequent recovery of PAOs than GAOs. Additionally, sulfides facilitated the production of extracellular polymeric substances (EPS), especially tightly bound EPS. The amount of EPS in GAOs was significantly higher than that in PAOs. The above results indicated that sulfide had a stronger inhibition to PAOs than GAOs, and when sulfide was present, GAOs had a competitive advantage over PAOs in EBPR. | |||||
206. 题目: Mono-/multiadsorption of chlorobenzene compounds on biochar: influence of the properties of the chlorobenzene molecules and biochar PurposeThis study aimed to explore the adsorption behaviors and mechanisms of chlorobenzene compounds (CBs; monochlorobenzene (MCB); 1,2-dichlorobenzene (1,2-DCB); pentachlorobenzene (PeCB); and hexachlorobenzene (HCB)) on corn straw-based biochar. Materials and methodsThe adsorption kinetics and isotherms of the four CBs were investigated in mono- or multi-CB adsorption experiments with the corn straw–based biochar which was pyrolyzed at 500 °C and modified with 1 mol/L HCl. Moreover, the surface morphology and porosity of the biochar were characterized. The molecular orbitals, electron cloud distribution, and configuration of the CBs were calculated by the quantum chemical method. The relationships were investigated among the adsorption behaviors and quantum chemical parameters of the CBs as well as the morphology characteristics of the biochar to explore the adsorption mechanisms of the CBs on the biochar. Results and discussionThe results showed that in both mono- and multi-adsorbate systems, the adsorption of the CBs was well fitted by the pseudo-second-order, Elovich, and the Freundlich model. The adsorption rates, affinities, and amounts indicated that the biochar preferably absorbed highly chlorinated CBs (PeCB and HCB) over low-chlorinated CBs (MCB and 1,2-DCB). The absolute electronegativity (χ), electrophilicity index (ω), polarizability (α), and molecular volume (Vm) followed the increasing order MCB < 1,2-DCB < PeCB < HCB. The values of energy gap of molecular frontier orbitals (ΔEGap) and molecular hardness (η) decreased with increasing halogen number of the CBs. The lower energy gap of molecular frontier orbitals, the less molecular stability, and higher deformability could favor the adsorption of highly chlorinated CBs (PeCB and HCB) on the biochar. ConclusionsDuring the adsorption process of the CBs on the biochar, physisorption and pore filling might be the two associated mechanisms. The biochar with properties (aromatization and porosity) matchable to the CBs in energy gap of molecular frontier orbitals, electrophilicity, and polarizability is available to enhance adsorption capacity to the greatest extent. The competitive adsorption might enhance the risk of CB mobility and bioavailability by reducing the adsorption amount and delaying the equilibrium time. | |||||
207. 题目: Spatial effects of nitrogen deposition on soil organic carbon stocks in patchy degraded saline-alkaline grassland Soil organic carbon (SOC) represents the largest carbon sink and plays a critical role in mitigating global warming. Elevated nitrogen (N) deposition has substantial effects on soil carbon sequestration in grassland ecosystems. However, almost no study has examined the effects of N deposition in widely degraded saline-alkaline grasslands. This is a critical knowledge gap because saline-alkaline degradation is one of the key global threats to carbon sequestration services provided by grasslands. Here, we conducted a 3-year N addition experiment in a patchy degraded saline-alkaline grassland to examine the effects of simulated N deposition on SOC stocks, along with spatial effects for five types of saline-alkaline degraded patches (multi-species-mixture patches; Leymus chinensis patches; Puccinellia tenuiflora patches; Chloris virgata patches and Artemisia anethifolia patches). N addition had no overall effect on SOC stocks in the degraded saline-alkaline grassland, but showed pronounced spatial effects depending on the saline-alkaline characteristics of degraded patches. Specifically, SOC decreased in multi-species-mixture patches with low saline-alkaline stress (soil 7 < pH < 8), but no change was observed in other types of degraded patches with high saline-alkaline stress (soil pH > 9). Although N addition promoted plant growth and increased aboveground biomass in all degraded patches, the resulting aboveground carbon input did not further contribute to soil carbon sequestration. Rather than aboveground biomass, soil pH was the critical controlling factor for soil carbon in the saline-alkaline grassland. However, N addition did not alter soil pH in all degraded patches. In multi-species-mixture patches with lightly saline-alkaline soils, N addition reduced species richness and increased microbial C:N ratio, which could accelerate soil carbon decomposition, thereby decreasing SOC stocks. Our findings suggest that increased global N deposition would not restore natural soil carbon in degraded saline-alkaline grassland, and instead, may further deteriorate soil carbon sequestration in lightly degraded patches with high plant diversity and low saline-alkaline stress. | |||||
208. 题目: Tree mycorrhizal type controls over soil water-extractable organic matter quantity and biodegradation in a subtropical forest of southern China Tree mycorrhizal type is believed to be a key factor controlling soil organic matter dynamics in forests, yet its effects on soil dissolved organic matter (DOM) quantity and biodegradation remain unknown, especially in sub/tropical forests. Here, we used soil water-extractable organic matter (WEOM) as a proxy for soil DOM, and measured water-extractable organic carbon (WEOC), total nitrogen (WETN), and total phosphorus (WETP) concentrations, and WEOM chemical composition (i.e., aromaticity and molecular weight) in the 0–10 cm and 10–30 cm mineral soil depths along the gradient ranging from arbuscular mycorrhizal (AM)- to ectomycorrhizal (ECM)-associated tree dominance in a subtropical secondary forest of southern China. Subsequently, we assessed soil WEOM biodegradation using a 42-day aerobic incubation experiment. At each soil depth, WEOC concentration and WEOC:WETN ratio increased with increasing ECM tree dominance, whereas WEOM aromaticity and molecular weight exhibited an opposite changing trend. Moreover, WEOC concentration correlated positively with soil organic C, total N, total P, and sand content, but correlated negatively with soil pH and clay and silt contents. Soil WEOM biodegradation did not change with ECM tree dominance in 0–10 cm depth but decreased with increasing ECM tree dominance in 10–30 cm depth. Soil WEOM biodegradation was negatively related to WEOC:WETP and WETN:WETP ratios, but was positively related to WEOM aromaticity and molecular weight. These findings suggested that tree mycorrhizal type is a potential indicator of soil DOM concentration and biodegradation, and highlight that the shifts in dominance of AM- and ECM-associated trees will influence soil DOM dynamics by altering soil texture, C:N:P stoichiometry, and C quality in subtropical forests. | |||||
209. 题目: Urban particulate water-soluble organic matter in winter: Size-resolved molecular characterization, role of the S-containing compounds on haze formation Water-soluble organic matter (WSOM), as a group of ubiquitous components in atmospheric PM, plays a crucial role in global climate change and carbon cycle. In this study, the size-resolved molecular characterization of WSOM in the range of 0.010–18 μm PM was studied to gain insights into their formation processes. The CHO, CHNO, CHOS, CHNOS compounds were identified by the ultrahigh-resolution Fourier transform ion cyclotron resonance mass spectrometry in ESI source mode. A bimodal pattern of the PM mass concentrations was found in the accumulation and coarse mode. The increasing mass concentration of PM was mainly attributed to the growth of large-size PM with the occurrence of haze. Both Aiken-mode (70.5–75.6 %) and coarse-mode (81.7–87.9 %) particles were proven the main carriers of the CHO compounds, the majority of which were indicated to be the saturated fatty acids and their oxidized derivatives. The S-containing (CHOS and CHNOS) compounds in accumulation-mode (71.5–80.9 %) increased significantly in hazy days, where organosulfates (C11H20O6S, C12H22O7S) and nitrooxy-organosulfates (C9H19NO8S, C9H17NO8S) were confirmed in majority. The S-containing compounds in accumulation-mode particle with high oxygen content (6–8 oxygen atoms), unsaturation degree (DBE < 4), and reactivity could facilitate the particle agglomeration and accelerate the haze formation. | |||||
210. 题目: Effects of dissolved organic matter derived from two herbs on the growth, physiology, and physico-chemical characteristics of four bloom-forming algae species While algal blooms occur frequently in lakes and reservoirs worldwide, the effects of dissolved organic matter (DOM) from lakeside and riparian zones on bloom formation are not well understood. In this study, we characterized the molecular composition of DOM from Cynodon dactylon (L.) Pers. (CD-DOM) and Xanthium sibiricum Patrin ex Widder (XS-DOM) and assessed their effects on the growth, physiology, volatile organic compounds (VOCs), and stable carbon isotope in four bloom-forming algae species (Microcystis aeruginosa, Anabaena sp., Chlamydomonas sp., and Peridiniopsis sp.). Stable carbon isotope analysis showed that the four species were affected by DOM. Both DOM types increased the cell biomass, polysaccharide and protein contents, chlorophyll fluorescence parameter values, and VOCs release of Anabaena sp., Chlamydomonas sp. and Microcystis aeruginosa, suggesting that DOM stimulated algal growth by increasing nutrient sources, photosynthetic efficiency, and stress tolerance. And in general, these three strains exhibited better growth at higher DOM concentrations. However, DOM treatment inhibited the growth of Peridiniopsis sp., as indicated by the increases in reactive oxygen species, damage in photosystem II reaction centers, and blockage in electron transport. Fluorescence analysis showed that tryptophan-like compounds were the main DOM components that affected algal growth. Molecular-level analysis suggested that unsaturated aliphatic compounds may be the most important DOM components. The findings indicate that CD-DOM and XS-DOM promote the blue-green algal blooms formation and thus should be considered in the management of natural water quality. | |||||
211. 题目: Comparative study for sorption of arsenic on peanut shell biochar and modified peanut shell biochar In this study, arsenite [As(III)] and arsenate [As(V)] removal efficiency of peanut shell biochar (PSB) and modified peanut shell biochar (MPSB) was compared in aqueous solutions. The modification was carried out with KMnO4 and KOH. Sorption efficiency of MPSB was relatively higher than PSB at pH 6 for As(III) (86%) and for As(V) (91.26%) for initial concentration of 1 mg/L, adsorbent dose of 0.5 g/L and 240 min equilibrium time at 100 rpm. Freundlich isotherm and pseudo-second order model suggested possible multilayer chemisorption. Fourier transform infrared spectroscopy showed that –OH, C-C, C=C and C-O-C groups contributed significantly in adsorption for both PSB and MPSB. Thermodynamic study showed that the adsorption process is spontaneous and endothermic. Regeneration studies revealed that PSB and MPSB can be successfully used for three cycles. This study established that peanut shell is low-cost, environment friendly and efficient biochar for removal of arsenic from water. | |||||
212. 题目: Current application of seaweed waste for composting and biochar: A review To address the origins of ocean acidification, seaweed aquaculture is emerging as a key biosequestration strategy. Nevertheless, seaweed biomass is involved in developing food and animal feed, whereas seaweed waste from commercial hydrocolloid extraction is dumped in landfills, which together limit the carbon cycle and carbon sequestration. This work sought to evaluate the production, properties, and applications of seaweed compost and biochar to strengthen the “carbon sink” implications of aquaculture sectors. Due to their unique characteristics, the production of seaweed-derived biochar and compost, as well as their existing applications, are distinct when compared to terrestrial biomass. This paper outlines the benefits of composting and biochar production as well as proposes ideas and perspectives to overcome technical shortcomings. If properly synchronized, progression in the aquaculture sector, composting, and biochar production, potentially promote various Sustainable Development Goals. | |||||
213. 题目: Development of novel kinetic model based on microbiome and biochar for in-situ remediation of total petroleum hydrocarbons (TPHs) contaminated soil A novel kinetic model has been developed to explain the degradation of total petroleum hydrocarbons. Microbiome engineered biochar amendment may result in a synergistic impact on degradation of total petroleum hydrocarbons (TPHs). Therefore, the present study analyzed the potential of hydrocarbon-degrading bacteria A designated as Aeromonas hydrophila YL17 and B as Shewanella putrefaciens Pdp11 morphological characterized as rod shaped, anaerobic and gram-negative immobilized on biochar, and the degradation efficiency was measured by gravimetric analysis and gas chromatography-mass spectrometry (GC-MS). Whole genome sequencing of both strains revealed the existence of genes responsible for hydrocarbon degradation. In 60 days remediation setup, the treatment consisting of immobilization of both strains on biochar proved more efficient with less half-life and better biodegradation potentials compared to biochar without strains for decreasing the content of TPHs and n-alkanes (C12–C18). Enzymatic content and microbiological respiration showed that biochar acted as a soil fertilizer and carbon reservoir and enhanced microbial activities. The removal efficiency of hydrocarbons was found to be a maximum of 67% in soil samples treated with biochar immobilized with both strains (A + B), followed by biochar immobilized with strain B 34%, biochar immobilized with strain A 29% and with biochar 24%, respectively. A 39%, 36%, and 41% increase was observed in fluorescein diacetate (FDA) hydrolysis, polyphenol oxidase and dehydrogenase activities in immobilized biochar with both strains as compared to control and individual treatment of biochar and strains. An increase of 35% was observed in the respiration rate with the immobilization of both strains on biochar. While a maximum colony forming unit (CFU/g) was found 9.25 with immobilization of both strains on biochar at 40 days of remediation. The degradation efficiency was due to synergistic effect of both biochar and bacteria based amendment on the soil enzymatic activity and microbial respiration. | |||||
214. 题目: Investigating hydrological transport pathways of dissolved organic carbon in cold region watershed based on a watershed biogeochemical model Dissolved organic carbon (DOC) is a significant component of regional and global carbon cycles and an important surface water quality indicator. DOC affects the processes of solubility, bioavailability and transport for a number of contaminants, such as heavy metals. Therefore, it is crucial to understand DOC fate and transport in the watershed and the transport pathways of DOC load. We modified a previously developed watershed-scale organic carbon model by incorporating the DOC load from glacier melt runoff and used the modified model to simulate periodic daily DOC load in the upper Athabasca River Basin (ARB) in the cold region of western Canada. The calibrated model achieved an overall acceptable performance for simulating daily DOC load with model uncertainties mainly from the underestimation of peak loads. Parameter sensitivity analysis indicates that the fate and transport of DOC load in upper ARB are mainly controlled by DOC production in the soil layers, DOC transport at the soil surface, and reactions in the stream system. The modeling results indicated that the DOC load is mainly from the terrestrial sources and the stream system was a negligible sink in the upper ARB. It also indicated that rainfall-induced surface runoff was the major transport pathway of DOC load in the upper ARB. However, the DOC loads transported by glacier melt runoff were negligible and only accounted for 0.02% of the total DOC loads. In addition, snowmelt-induced surface runoff and lateral flow contributed 18.7% of total DOC load, which is comparable to the contribution from the groundwater flow. Our study investigated the DOC dynamics and sources in the cold region watershed in western Canada and quantified the contribution of different hydrological pathways to DOC load, which could provide a useful reference and insight for understanding watershed-scale carbon cycle processes. | |||||
215. 题目: Novel insight into arsenic enrichment in aquifer sediments under different paleotemperatures from a molecular-level characterization of sedimentary organic matter The heterogeneous distribution of As in sediments is governed by the abundance and type of SOM, which is closely associated with the depositional environment. However, few studies have revealed the effect of depositional environment (e.g., paleotemperature) on As sequestration and transport in sediments from the perspective of the molecular characteristics of sedimentary organic matter (SOM). In this study, we characterized the optical and molecular characteristics of SOM coupled with organic geochemical signatures to illustrate in detail the mechanisms of sedimentary As burial under different paleotemperatures. We identified that alternating paleotemperature changes result in the fluctuation of H-rich and H-poor organic matter in sediments. Further, we found aliphatic and saturated compounds with higher nominal oxidation state of carbon (NOSC) values predominate under high-paleotemperature (HT) conditions, while polycyclic aromatics and polyphenols with lower NOSC values accumulate under low-paleotemperature (LT) conditions. Under LT conditions, thermodynamically favorable organic compounds (higher NOSC values) are preferentially degraded by microorganisms to provide sufficient energy to sustain sulfate reduction, favoring sedimentary As sequestration. Under HT conditions, the energy gained from the decomposition of low NOSC value organic compounds approaches the energy required to sustain dissimilatory Fe reduction, leading to sedimentary As release into groundwater. This study provides molecular-scale evidence of SOM that indicates LT depositional environments favor sedimentary As burial and accumulation. | |||||
216. 题目: Insights into Mechanisms of Novel Engineered Biochar Derived from Neem Chips via Iron Catalyst for the Removal of Methyl Orange from Aqueous Phase Methyl orange (MO) is a toxic dye used in many industrial processes. The removal of MO is considered expensive by the sophisticated treatment methods. Hence, there is a need for the discovery of novel methods for removing MO from polluted water. Therefore, this study was aimed at understanding the scientific insights into the adsorption mechanism of novel engineered biochar derived from neem chips via catalytic conversion with FeCl3 for the MO removal. This is the first report describing the use of novel engineered biochar derived from waste neem chip biomass for the removal of the highly resistant anionic dye “methyl orange” by understanding the insights into the removal mechanism. The biochar was prepared at different temperatures: 200 °C, 400 °C, 600 °C, and 800 °C, with a residence time of 2 h. An adsorptive experiment was planned, under a set of experimental conditions: dosage 1 g/L; pH 6; rpm 150; holding time 72 h, to identify the best biochar. The selected biochar has then been activated by iron catalyst of different concentrations (1%, 3%, 5%, and 7%) at a temperature of 700 °C for 30 min. The adsorptive performance was then checked. The engineered biochar with a high qe value (amount of adsorbate removed by unit weight of engineered biochar) was selected, for the detailed studies; isotherm, kinetics, thermodynamics, and rate-limiting factor analyses were used to understand the adsorptive mechanism of novel engineered biochar synthesized. Moreover, it was also treated with wastewater to check its removal efficiency. Furthermore, point zero charge (pzc) was analyzed to study the functional properties of novel engineered biochar along with XRD analysis. The outcomes revealed that the FeCl3 activation improved the (qe) amount of adsorbate removed by grams of engineered biochar to 63.39 mg/g from 80.30 mg/g and it improved the aromatic carbon network. Moreover, the adsorption nature of novel engineered biochar to MO removal is multilayer. It also obeyed well for the pseudo-second-order kinetics. The adsorption is spontaneous and endothermic. The engineered biochar synthesized performed well to remove impurities from a real industrial wastewater: Removal of total suspended solids was 68% and removal of total solids was 74%. Therefore, the engineered biochar produced by the iron catalytic conversion of neem chips is a novel adsorbent for MO removal from aqueous phase. Graphical | |||||
217. 题目: Lignite drove phenol precursors to participate in the formation of humic acid during chicken manure composting This study set out to explore the impact of lignite on preserving organic matter and promoting the formation of humic acid (HA) during chicken manure composting. Composting test was carried out for control (CK), 5 % lignite addition treatment (L1), 10 % addition treatment (L2) and 15 % addition treatment (L3). The results demonstrated that lignite addition effectively reduced the loss of organic matter. The HA content of all lignite-added groups was higher than that of CK, and the highest was 45.44 %. L1 and L2 increased the richness of bacterial community. Network analysis showed higher diversity of HA-associated bacteria in L2 and L3 treatments. Structural equation models revealed that reducing sugar and amino acid contributed to the formation of HA during CK and L1 composting, while polyphenol contributed more to the HA formation during L2 and L3 composting. Furthermore, lignite addition also could promote the direct effect of microorganisms on HA formation. Therefore, the addition of lignite had practical significance to enhance compost quality. | |||||
218. 题目: Identification of the cause of the difference among TOC quantitative methods according to the water sample characteristics Total organic carbon (TOC) analysis with accurate determination of particulate organic carbon (POC) content in suspended solids (SS) containing water is critical for evaluating the environmental impact of particulate organic pollutants in water and calculating the carbon cycle mass balance. TOC analysis is divided into the non-purgeable organic carbon (NPOC) and differential (known as TC-TIC) methods; although the selection of method is greatly affected by the sample matrix characteristics of SS, no studies have investigated this. This study quantitatively evaluates the effect of SS containing inorganic carbon (IC) and purgeable organic carbon (PuOC), as well as that of sample pretreatment, on the accuracy and precision of TOC measurement in both methods for various environmental water sample types (12 wastewater influents and effluents and 12 types of stream water). For influent and stream water with high SS, the TC-TIC method expressed 110–200 % higher TOC recovery than that for the NPOC method due to POC component losses in SS owing to its conversion into PuOC during sample pretreatment (using ultrasonic) and subsequent loss in the NPOC purging process. Correlation analysis confirmed that particulated organic matter (POM, mg/L) content in SS directly affected this difference (r > 0.74, p < 0.01, n = 24); for POC water samples (those containing >10 mg/L of POM) featuring purgeable dissolved organic matter, TC-TIC was appropriate in securing TOC measurement accuracy. In constrast, in effluent and stream water with low SS (i.e., < ~5 mg/L) and high IC (> 70 %) contents, the TOC measurement ratios (TC-TIC/NPOC) of both methods were similar, between 0.96 and 1.08, suggesting that NPOC is appropriate for improving precision. Our results provide useful basic data to establish the most reliable TOC analysis method considering SS contents and its properties along with the matrix characteristics of the sample. | |||||
219. 题目: High-resolution patterns and inequalities in ambient fine particle mass (PM2.5) and black carbon (BC) in the Greater Accra Metropolis, Ghana Growing cities in sub-Saharan Africa (SSA) experience high levels of ambient air pollution. However, sparse long-term city-wide air pollution exposure data limits policy mitigation efforts and assessment of the health and climate effects in growing cities. In the first study of its kind in West Africa, we developed high resolution spatiotemporal land use regression (LUR) models to map fine particulate matter (PM2.5) and black carbon (BC) concentrations in the Greater Accra Metropolitan Area (GAMA), one of the fastest sprawling metropolises in SSA. We conducted a one-year measurement campaign covering 146 sites and combined these data with geospatial and meteorological predictors to develop separate Harmattan and non-Harmattan season PM2.5 and BC models at 100 m resolution. The final models were selected with a forward stepwise procedure and performance was evaluated with 10-fold cross-validation. Model predictions were overlayed with the most recent census data to estimate the population distribution of exposure and socioeconomic inequalities in exposure at the census enumeration area level. The fixed effects components of the models explained 48–69 % and 63–71 % of the variance in PM2.5 and BC concentrations, respectively. Spatial variables related to road traffic and vegetation variables explained the most variability in the non-Harmattan models, while temporal variables were dominant in the Harmattan models. The entire GAMA population is exposed to PM2.5 levels above the World Health Organization guideline, including even the Interim Target 3 (15 μg/m3), with the highest exposures in poorer neighborhoods. The models can be used to support air pollution mitigation policies, health, and climate impact assessments. The measurement and modelling approach used in this study can be adapted to other African cities to bridge the air pollution data gap in the region. | |||||
220. 题目: Low-rate ferrate dosing damages the microbial biofilm structure through humic substances destruction and facilitates the sewer biofilm control The microbial activities in sewer biofilms are recognized as a major reason for sewer pipe corrosion, malodor, and greenhouse gas emissions. However, conventional methods to control sewer biofilm activities were based on the inhibitory or biocidal effect of chemicals and often required long exposure time or high dosing rates due to the protection of sewer biofilm structure. Therefore, this study attempt to use ferrate (Fe(VI)), a green and high-valent iron, at low dosing rates to damage the sewer biofilm structure so as to enhance sewer biofilm control efficiency. The results showed the biofilm structure started to crush when the Fe(VI) dosage was 15 mg Fe(VI)/L and the damage enhanced with the increasing dosage. The determination of extracellular polymeric substances (EPS) showed that Fe(VI) treatment at 15-45 mgFe/L mainly decreased the content of humic substances (HS) in biofilm EPS. This is because the functional groups, such as C-O, -OH, and C=O, which held the large molecular structure of HS, were the primary target of Fe(VI) treatment as suggested by 2D-Fourier Transform Infrared spectra. As a result, the coiled chain of EPS maintained by HS was turned to extended and dispersed and consequently led to a loosed biofilm structure. The XDLVO analysis suggested that both the microbial interaction energy barrier and secondary energy minimum were increased after Fe(VI) treatment, suggesting that the treated biofilm was less likely to aggregate and easier to be removed by the shear stress caused by high wastewater flow. Moreover, combined Fe(VI) and free nitrous acid (FNA) dosing experiments showed for achieving 90% inactivation, the FNA dosing rate could be reduced by 90% with the exposure time decreasing by 75% at a low Fe(VI) dosing rate and the total cost was substantially decreased. These results suggested that applying low-rate Fe(VI) dosing for sewer biofilm structure destruction is expected to be an economical way to facilitate sewer biofilm control. | |||||
