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النتائج 4061 - 4070 من 7,292
Predicting wetland area and water depth in Barind plain of India النص الكامل
2022
Singha, Pankaj | Pal, Swades
The present study attempts to delineate wetlands in the lower Tangon river basin in the Barind flood plain region using spectral water body extraction indices. The main objectives of this present study are simulating and predicting wetland areas using the advanced artificial neural network-based cellular automata (ANN-CA) model and water depth using statistical (adaptive exponential smoothing) as well as advanced machine learning algorithms such as Bagging, Random Subspace, Random Forest, Support vector machine, etc. The result shows that RmNDWI and NDWI are the representative wetland delineating indices. NDWI map was used for water depth prediction. Regarding the prediction of wetland areas, a remarkable decline is likely to be identified in the upcoming two decades. The small wetland patches away from the master stream are expected to dry out during the predicted period, where the major wetland patches nearer to the master stream with greater water depth are rather sustainable, but their depth of water is predicted to be reduced in the next decades. All models show satisfactory performance for wetland depth mapping, but the random subspace model was identified as the best-suited water depth predicting method with an acceptable prediction accuracy (root mean square error <0.34 in all the years) and the machine learning models explored better result than adaptive exponential smoothing. This recent study will be very helpful for the policymakers for managing wetland landscape as well as the natural environment.
اظهر المزيد [+] اقل [-]Ecotoxicological and health implications of microplastic-associated biofilms: a recent review and prospect for turning the hazards into benefits النص الكامل
2022
Okeke, Emmanuel Sunday | Ezeorba, Timothy Prince Chidike | Chen, Yao | Mao, Guanghua | Feng, Weiwei | Wu, Xiangyang
Microplastics (MPs), over the years, have been regarded as a severe environmental nuisance with adverse effects on our ecosystem as well as human health globally. In recent times, microplastics have been reported to support biofouling by genetically diverse organisms resulting in the formation of biofilms. Biofilms, however, could result in changes in the physicochemical properties of microplastics, such as their buoyancy and roughness. Many scholars perceived the microplastic-biofilm association as having more severe consequences, providing evidence of its effects on the environment, aquatic life, and nutrient cycles. Furthermore, other researchers have shown that microplastic-associated biofilms have severe consequences on human health as they serve as vectors of heavy metals, toxic chemicals, and antibiotic resistance genes. Despite what is already known about their adverse effects, other interesting avenues are yet to be fully explored or developed to turn the perceived negative microplastic-biofilm association to our advantage. The major inclusion criteria for relevant literature were that it must focus on microplastic association biofilms, while we excluded papers solely on biofilms or microplastics. A total of 242 scientific records were obtained. More than 90% focused on explaining the environmental and health impacts of microplastic-biofilm association, whereas only very few studies have reported the possibilities and opportunities in turning the microplastic biofilms association into benefits. In summary, this paper concisely reviews the current knowledge of microplastic-associated biofilms and their adverse consequences and further proposes some approaches that can be developed to turn the negative association into positive.
اظهر المزيد [+] اقل [-]Nanofiltration Membrane Fouling and Control Caused by Residual Aluminum in Feed Water النص الكامل
2022
Yu, Hui-Bo | Zhang, Xian-Qiu | Han, Xue | Yang, Zhen-Zhen | Zhou, Ya-Wen | Ding, Wen | Du, Ming-Xia
It is reported that residual aluminum from coagulation pretreatment can increase membrane fouling in nanofiltration (NF) or reverse osmosis (RO) desalination systems. However, the membrane fouling mechanism of residual aluminum and the effective control measures are not very clear. In this study, the nanofiltration membrane fouling caused by poly-aluminum chloride (PACl), the inhibitory effect of amino trimethylene phosphonic acid (ATMP) on aluminum foulants, and calcium carbonate scale in the presence of residual aluminum were investigated by permeate experiments and scanning electron microscopy (SEM) observation of the fouled membranes. Besides, the effect of adding ultrafiltration before nanofiltration on reducing membrane fouling caused by residual aluminum was also investigated. The results showed that most of the residual aluminum in feed eventually formed insoluble particles and fine flocs, and accumulated gradually on the membrane surface, which was a typical colloid particle fouling. ATMP can reduce the membrane fouling caused by residual aluminum to some extent, and the permeate flux ratio (J/Jc) increased from 0.83 to 0.89 when ATMP increased to the optimal dose of 6 mg⋅L⁻¹. However, this means can still effectively eliminate carbonate scale, even in the presence of residual aluminum. Moreover, ultrafiltration pretreatment prior to nanofiltration was very effective to control membrane fouling, and the comprehensive cost was calculated to be only 0.006 $⋅m⁻³. Therefore, the combined process of coagulation-ultrafiltration as a pretreatment of nanofiltration or reverse osmosis should be an ideal way to prevent membrane fouling caused by residual aluminum.
اظهر المزيد [+] اقل [-]Application of titanium dioxide immobilized on a cellulosic material for the photocatalytic degradation of Acid Black 24 dye in a continuous flow cascade reactor النص الكامل
2022
Salhi, Anas | Esserrar, Sana | Nechchadi, Bouchra | El Amine Ghanjaoui, Mohammed | Aguedache, Abdelkahhar | El Krati, Mohammed | Tahiri, Soufiane
The aim of this work is the study of the photocatalytic degradation of Acid Black 24 dye (AB24), in a continuous flow cascade reactor, using titanium dioxide (TiO₂) immobilized on a cellulosic material. The results obtained demonstrated a synergistic effect of the two phenomena adsorption and photocatalysis. The effects of various parameters that affect the dye removal efficiency were investigated. The best photocatalytic degradation yield of AB24 molecules is obtained in acidic medium because of the strong attraction between the positively charged catalyst and the anionic dye molecules. The optimum times for obtaining the best yields depend on the initial concentration of the dye, the volume of the treated solution, and the feed rate of the reactor. In addition, reusing the catalytic material several times is technically possible; this can decrease the cost of treatment for a possible industrial scale application.
اظهر المزيد [+] اقل [-]Multi-isotopes revealing the coastal river anthropogenic pollutants and natural material flux to ocean: Sr, C, N, S, and O isotope study النص الكامل
2022
Zhang, Shitong | Han, Guilin | Zeng, Jie | Liu, Man | Li, Xiaoqiang | Liu, Jinke
Coastal river exports massive terrestrial materials to the adjacent marine environment with information about chemical weathering, providing critical insights on riverine flux and the potential impact on marine ecosystem. In this study, the preliminary data of dissolved strontium (Sr) and ⁸⁷Sr/⁸⁶Sr in a typical coastal river in southeastern China were collected along with hydrochemistry and C, N, S, and O isotopes to discriminate the source of terrestrial weathering and the riverine flux. Sr concentrations exhibited a range of 0.084 ~ 1.307 μmol L⁻¹, and ⁸⁷Sr/⁸⁶Sr values ranged 0.7089 ~ 0.7164. The total cationic charge (TZ⁺) ranged 0.2 ~ 11.7 meq L⁻¹ with the predominant Ca²⁺ which accounted for > 50% of TZ⁺, while the anions were dominated by HCO₃⁻. The extremely high Na⁺ and Cl⁻ near the estuary indicated seawater mixing in such a coastal river. δ¹³C-DIC, δ¹⁵N-NO₃⁻, δ¹⁸O-NO₃⁻, and δ³⁴S-SO₄²⁻ of river water ranged − 24.1‰ ~ − 9.2‰, 0.3‰ ~ 22.7‰, − 2.1‰ ~ 21.4‰, and − 9.3‰ ~ 18.0‰, respectively. δ¹³C enhanced correspondingly to decreased δ³⁴S, confirming the attendance of H₂SO₄ in carbonate weathering. Most δ¹⁸O values exhibited within ± 10‰, indicating the dominant nitrification process. δ¹⁵N presented slightly negative relationship with δ¹³C and no obvious correlation with δ³⁴S, indicating relatively limited impact of denitrification. The depleted δ¹³C and δ¹⁵N may be attributed to carbonate dissolution with nitric acids and the oxidation of organic matters into C and N pools. Quantitative analysis revealed that silicate weathering accounts for 79% of total dissolved Sr, indicating the dominant weathering process. The estimated monthly flux of dissolved Sr to the East China Sea was 138.1 tons, demonstrating an potential impact on seawater Sr isotope evolution. Overall, the investigations of multi-isotopes revealed the enhancement of weathering rates and the consequently depleted CO₂ consumption, which further proved the involvement of strong acids (H₂SO₄ and HNO₃). This study provides scientific insight in terrestrial weathering and anthropogenic impact of a typical coastal watershed and may orient the management of environmental issues related to coastal ecosystems.
اظهر المزيد [+] اقل [-]The impact of drivers’ short-term exposure to air pollution on traffic deaths النص الكامل
2022
Shi, Daqian | Liu, Ziwei | Fu, Jie | Yu, Hongwei
Air pollution may decrease drivers’ driving performance thus leading to traffic accidents, but this impact is almost ignored in existing literature. We investigate the short-term effect of air pollution on traffic deaths using the high-dimensional fixed effect model and instrument variable method based on the daily-city panel data in China from 2013 to 2018. The results show that drivers’ short-term exposure to air pollution significantly increases the number of traffic deaths. For every 1 ug/m³ increase of PM2.5 concentration each day, the daily number of traffic deaths will increase by 0.64%. The impacts of air pollution on traffic deaths can last for 2 days. We also find that impact varies from different driver groups.The male, the young (age under 22), the elderly (age over 60), and the two-wheeler drivers are more vulnerable. Worse air pollution may associate with more bad driving behaviors and less good manners. In this article, we reveal a new factor that leads to traffic deaths, i.e., air pollution, and we also put forward some prevention strategies which may provide policy references for traffic safety.
اظهر المزيد [+] اقل [-]How FDI and technology innovation mitigate CO2 emissions in high-tech industries: evidence from province-level data of China النص الكامل
2022
Wang, Zhaocheng | Gao, Lijuan | Wei, Zixiang | Majeed, Abdul | Alam, Iqbal
The high technology (high-tech) industry of China has gained a key strategic position in the Chinese economic goals. In this positioning, foreign direct investment (FDI) and technological innovation have emerged as strong pillars of the high-tech industry. However, there are growing concerns of carbon emission from this industry which is still debatable. In this context, this study measures the effect of FDI and technology innovation on carbon emissions in the high-tech industry from 28 provinces of China. The study uses the provincial data for China over the period 2000–2018. In addition to examining unit root properties, structural breaks, and cointegration, this study uses quantile regression for estimating long-run relationships among study variables. The findings reveal the negative impact of FDI on carbon emissions. Technology innovation positively impacts in the initial three quantiles, whereas negatively impacts in the next six quantiles. These results indicate that FDI and technology innovation have shaped the energy intensity in the high-tech industry, which causes fluctuation in carbon emissions over time. After controlling the effects of urbanization, energy intensity, and economic growth, this study recommends that policymakers should emphasize on the heterogeneous effects of FDI and technology-lead emissions at different quantiles during the process of CO₂ emission reduction.
اظهر المزيد [+] اقل [-]Effective photocatalytic degradation of amoxicillin using MIL-53(Al)/ZnO composite النص الكامل
2022
Fawzy, Asmaa | Mahanna, Hani | Mossad, Mohamed
A promising hierarchical nanocomposite of MIL-53(Al)/ZnO was synthesized as a visible-light-driven photocatalyst to investigate the degradation of amoxicillin (AMX). MIL-53(Al)/ZnO ultrafine nanoparticles were obtained by preparing Zn-free MIL-53Al and employing it as a reactive template under hydrothermal and chemical conditions. The synthesized nanocomposite (MIL-53(Al)/ZnO) has a low content of Al > 1.5% with significantly different characterizations of the parent compounds elucidated by various analyses such as SEM, TEM, XRD, EDX, and UV–Vis. The effect of operational parameters (catalyst dose (0.2–1.0 g/L), solution pH (3–11), and initial AMX concentration (10–90 mg/L)) on the AMX removal efficiency was studied and optimized by the response surface methodology. A reasonable goodness-of-fit between the expected and experimental values was confirmed with correlation coefficient (R²) equal to 0.96. Under the optimal values, i.e., initial AMX concentration = 10 mg/L, solution pH ~ 4.5, and catalyst dose = 1.0 g/L, 100% AMX removal was achieved after reaction time = 60 min. The degradation mechanism and oxidation pathway were vigorously examined. The AMX degradation ratios slightly decreased after five consecutive cycles (from 78.19 to 62.05%), revealing the high reusability of MIL-53(Al)/ZnO. The AMX removal ratio was improved with enhancers in order ([Formula: see text]> H₂O₂ > S₂O₈⁻²). The results proved that 94.12 and 98.23% reduction of COD were obtained after 60 and 75 min, respectively. The amortization and operating costs were estimated at 3.3 $/m³ for a large-scale photocatalytic system.
اظهر المزيد [+] اقل [-]Surface functionalization of natural hydroxyapatite by polymerization of β-cyclodextrin: application as electrode material for the electrochemical detection of Pb(II) النص الكامل
2022
Tchoffo, Rodrigue | Ngassa, Guy B. P. | Doungmo, Giscard | Kamdem, Arnaud T. | Tonlé, Ignas K. | Ngameni, Emmanuel
A composite material prepared by polymerization of β-cyclodextrin (β-CD) on the surface of natural hydroxyapatite using citric acid as cross linker, was employed as electrode material for the detection of Pb(II). Hydroxyapatite was obtained from bovine bones, following a three-step procedure including pre-calcination, chemical treatment with (NH₄)₂HPO₄, and calcination. The structure and morphology of the pristine hydroxyapatite (NHAPP₀.₅) and its functionalized counterpart (NHAPₚ₀.₅-CA-β-CD) were examined using XRD, FTIR, and SEM. Upon deposition as thin film on a glassy carbon electrode (GCE), the ion exchange ability of NHAPₚ₀.₅-CA-β-CD was exploited to elaborate a sensitive sensor for the detection of lead. The electroanalytical procedure was based on the chemical accumulation of Pb(II) ions under open-circuit conditions, followed by the detection of the preconcentrated species using differential pulse anodic stripping voltammetry. The reproducibility of the proposed method, based on a series of 8 measurements in a solution containing 2 μM Pb(II) gave a coefficient of variation of 1.27%. Significant parameters that can affect the stripping response of Pb(II) were optimized, leading to a linear calibration curve for lead in the concentration range of 2 × 10⁻⁸ mol L⁻¹ – 20 × 10⁻⁸ mol L⁻¹ (R² = 0.998). The detection limit (3S/m) and the sensitivity of the proposed sensor were 5.06 × 10⁻¹⁰ mol L⁻¹ and 100.80 μA.μM⁻¹, respectively. The interfering effect of several ions expected to affect the determination of lead was evaluated, and the proposed sensor was successfully applied in the determination of Pb(II) ions in spring water, well water, river water and tap water samples.
اظهر المزيد [+] اقل [-]Performance Evaluation of A/O Membrane Bioreactor System in the Effective Removal of Endocrine-Disrupting Chemicals: the Effect of SRT and Flux Rate النص الكامل
2022
Sözüdoğru, Onur | Koçoğlu, Elif Seda | Yılmaz, Alper Erdem | Bakırdere, Sezgin | Komesli, Okan Tarık
The effect of SRT and flux rate on the removal of endocrine-disrupting chemicals (EDCs), which have serious adverse effects on human and wildlife endocrine systems, by the laboratory scale submerged flat-sheet anoxic/oxic MBR system (A/O MBR), was investigated. The A/O MBR system was operated for four different sludge holding times (SRT: 10 days, 15 days, 25 days, and 30 days) and three different fluxes’ (13 L/m²·h, 18 L/m²·h, and 26 L/m²·h) removal of EDCs (carbamazepine, bisphenol A, methylparaben, ethylparaben, 17α-ethinylestradiol, β-estradiol, estrone, tonalide, galaxolide, and triclosan) was investigated. The A/O MBR system ensures higher removal of all EDCs (> 86%) except for carbamazepine (34%) at high SRT (30d) and low flux (13 L/m²·h). SRT and flux rate could be vital operating parameters for the removal of carbamazepine, ethylparaben, triclosan, and 17α-ethinylestradiol; however, there might not be a significant effect on the removal of bisphenol A (> 90%), methylparaben (> 91), β-estradiol (> 99%), estrone (> 99%), tonalide (> 99%), and galaxolide (> 99%). The removal of ethylparaben, 17α-ethinylestradiol, triclosan, and carbamazepine with A/O MBR at high sludge age (30 day) and low flux (13 L/m²·h) were 93.3%, 96.9%, 86.9%, and 34.8%, respectively. When the SRT was reduced to 10 days, and the flux was increased to 26 L/m²·h, the removal efficiency of ethylparaben, 17α-ethinylestradiol, triclosan, and carbamazepine decreased to 72.7%, 77.2%, 52.4%, and 1.06%, respectively. It found that SRT and flux rate could be vital parameters for the removal of carbamazepine, ethylparaben, triclosan, and 17α-ethinylestradiol; however, there might not be a significant effect on the removal of bisphenol A, methylparaben, β-estradiol, estrone, tonalide, and galaxolide.
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