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A study on water quality prediction by a hybrid CNN-LSTM model with attention mechanism 全文
2021
Atwill, Yurong Y. | Xiong, Qingyu | Wu, Chao | Zou, Qinghong | Yu, Yang | Yi, Hualing | Gao, Min
The water environment plays an essential role in the mangrove wetland ecosystem. Predicting water quality will help us better protect water resources from pollution, allowing the mangrove ecosystem to perform its normal ecological role. New approaches to solve such nonlinear problems need further research since the complexity of water quality data and they are easily affected by the noise. In this paper, we propose a water quality prediction model named CNN-LSTM with Attention (CLA) to predict the water quality variables. We conduct a case study on the water quality dataset of Beilun Estuary to predict pH and NH₃-N. Linear interpolation and wavelet techniques are used for missing data filling and data denoising, respectively. The hybrid model CNN-LSTM is highly capable of resolving nonlinear time series prediction problems, and the attention mechanism captures longer time dependence. The experimental results show that our model outperforms other ones, and can predict with different time lags in a stable manner.
显示更多 [+] 显示较少 [-]Catalytic activity comparison of natural ferrous minerals in photo-Fenton oxidation for tertiary treatment of dyeing wastewater 全文
2021
Lu, Jun | Chen, Quanyuan | Zhao, Qi | Liu, Xiaochen | Zhou, Juan
Natural ferrous minerals are readily available and recyclable catalysts in photo-Fenton-like oxidation for wastewater treatment. In this work, typical ferrous oxide and sulfide minerals including magnetite, chalcopyrite, and pyrrhotite were exploited as catalysts in heterogeneous photo-Fenton oxidation for purification of biological effluent of dyeing wastewater. In a wide initial pH range (3.0~7.5), ferrous mineral-based heterogeneous photo-Fenton-like reactions were proven to be effective on the oxidation of recalcitrant pollutants. COD removals achieved 60.57%, 58.83%, and 57.41% using pyrrhotite, chalcopyrite, and magnetite, respectively, as catalyst under ultraviolet irradiation of 220~275 nm at H₂O₂ concentration of 9.8 mM. The corresponding COD removals were 51.75% and 34.09% with or without ferrous sulfate additions in UV/H₂O₂ systems. Minerals exhibited excellent stability and reusability with photo-catalytic activity reduction of less than 10% in the reuse of 5 cycles. Dissolved iron concentrations were determined to be 1.86 mg L⁻¹, 4.62 mg L⁻¹, and 7.53 mg L⁻¹ for magnetite, chalcopyrite, and pyrrhotite, respectively, at pH 3 and decreased to zero in neutral pH environment, which were much lower than those required for homogenous Fenton reaction. It was deduced that oxidation of recalcitrant pollutants was mainly catalyzed by Fe(II) on the mineral surface. The more reactive oxygen species such as hydroxyl radicals were resulted from the reaction of surface Fe (II) with H₂O₂, H₂O₂ photolysis, and charge separation of minerals under UV irradiation.
显示更多 [+] 显示较少 [-]Does the new-type urbanization construction improve the efficiency of agricultural green water utilization in the Yangtze River Economic Belt? 全文
2021
Ding, Xuhui | Cai, Zhongyao | Fu, Zhu
It is very important to control agricultural water pollution and promote agricultural water saving, for high-quality development of Yangtze River Economic Belt (YREB). The efficiency of agricultural green water utilization (EAGWU) needs financial and technical support from the new-type urbanization, which also change agricultural production mode and resource utilization level. This paper introduces non-point source water pollution into the output, adopts the super efficiency-slack model (SE-SBM) to measure the EAGWU, and uses difference generalized method of moments (DIF-GMM) to examine how new-type urbanization affects EAGWU from its four core characteristics. The results of EAGWU show that the overall efficiency value has been increasing rapidly in the research period, while the eastern provinces performed better and the central provinces performed worse. On the other hand, the overall difference in EAGWU first diverged and then shrunk, while economically developed provinces has been converging all the time. The results of driving factor estimation show that population urbanization has a significantly positive effect on EAGWU, with the rural labor force transfer and agricultural land circulation. Economic urbanization and urban-rural integration have negative effects, with the widening gap of absolute income and the compressed space of agricultural development. The EAGWU lag phase has a positive effect, because of the ratchet or cumulative effect, while equilibrium-urbanization has an insignificant effect. The conclusions will provide preferable recommendations for decision-making of green and water-saving development in agriculture.
显示更多 [+] 显示较少 [-]Iron, thermal stratification, Eucalyptus sp., and hypoxia: drivers to water blackening in southern China reservoirs 全文
2021
Li, Yiping | Norgbey, Eyram | Zhu, Ya | Nwankwegu, Amechi S. | Bofah-Buoh, Robert | Anim, Desmond | Takyi- Annan, Georgina Esi | Nuamah, Linda | Banahene, Patrick | Pu, Yashui | Huang, Yanan
The management of black water depends primarily on the knowledge of the dynamics of organic matter (OM), iron (Fe), sulfide (S), and manganese (Mn), at the water-sediment boundary (WSB). However, the mechanistic path of these substances leading to black water remains unsettled. In this study, a 35-day field study was conducted using the thin-film diffusion gradient technology (DGT) and the planar optrode to address the unknown combined effects of Fe, Mn, OM, S, and tannins from Eucalyptus species on Tianbao reservoir.Our results indicated that the hypolimnion was hypoxic due to thermal stratification, which caused the reduction of insoluble Fe and Mn from sediments to bottom water. Correlation analysis (Fe:S (r:0.5–0.9); Mn:S (r:0.2–0.8)) and elevated fluxes (Fe²⁺, Mn²⁺, S²⁻) connoted that these parameters interacted chemically to give black matter. The content of OM, Fe²⁺, and tannic acid in the benthic region diminished remarkably (p < 0.05) from day 1 (strong stratification) to day 35 (weak stratification), connoting that these parameters also interacted chemically to give black matter. The turbidity (clarity of the water) increased from day 1 to 35 with a significant difference (p < 0.05) recorded on day 14 confirming that black water was formed on this day when the thermal structure of the reservoir was annihilated. Correlation analysis supported the assertion that the variability in oxygen and redox conditions caused changes in Fe, Mn, and OM content at the WSB.The finding from the field research provides useful information to stakeholders on how to improve the quality of freshwater management designs.
显示更多 [+] 显示较少 [-]Mechanism and Optimization of Polyepoxysuccinic Acid in Washing Cd-, Pb-, and Zn-Contaminated Soils 全文
2021
Zhong, Qinmei | Li, Linxian | Zhang, Shirong | Li, Ting | Xu, Xiaoxun | Wang, Guiyin | Li, Yun
Soil washing is an important technique for remediating metal-contaminated soils, and screening promising eluant and optimizing its washing conditions can enhance the restoration efficiencies. Biodegradable polyepoxysuccinic acid (PESA) was employed to remove Cd, Pb, and Zn from two contaminated soils. FTIR analysis suggested that PESA washing process may be dominated by dispersion effect and associated with chelating function. The effects of PESA concentration, pH of solution, and washing time on heavy metal removal were conducted. Single-factor experiments showed that Cd, Pb, and Zn removal was 72.8, 75.7, and 47.7% for soil A and 61.1, 70.2, and 43.3% for soil B at PESA concentration of 30.0 mmol L⁻¹, pH 3.0, and washing time of 2.0 h. Furthermore, rotatable orthogonal central combination design (ROCCD) was conducted to optimize the washing parameters. The optimal experiment intervals of PESA concentration, pH, and washing time were 38.0–39.0 mmol L⁻¹, 3.0, and 2.0–2.4 h. Under these conditions, Cd, Pb, and Zn could be removed 80.4, 66.0, and 47.8% from soil A and 64.9, 67.4, and 43.3% from soil B, respectively. Therefore, PESA is a potential extracting agent to remove heavy metals from contaminated soils, and ROCCD is an effective reliable tool for optimization washing parameters.
显示更多 [+] 显示较少 [-]A subchronic low-dose exposure of a glyphosate-based herbicide induces depressive and anxious-like behavior in mice: quercetin therapeutic approach 全文
2021
Bicca, Diogo Ferreira | Spiazzi, Cristiano Chiapinotto | Ramalho, Juliana Bernera | Soares, Melina Bucco | Cibin, Francielli Weber Santos
In this study, we investigated the possible role of pesticide exposure in contributing to neurological diseases such as depression. Here, we evaluated whether a subchronic low dose of a glyphosate-based herbicide (GBH) could induce alterations in the central nervous system, using the flavonoid quercetin as a therapeutic strategy. Forty mice were divided into four treatment groups: control, GBH, quercetin, and GBH+Quer groups and received 50 mg/kg of GBH solution, 30 mg/kg of quercetin, and/or vehicles for 30 days via gavage. After performing behavioral tests, such as the open field (OF), elevated plus maze (EPM), forced swim test (FST), and sucrose preference test (SPT), the mice were euthanized and their hippocampal tissues were collected to measure the levels of oxidative stress markers such as reactive species (RS), total antioxidant capacity (FRAP), reduced glutathione (GSH), and acetylcholinesterase activity (AChE), as well as for histological evaluation. The GBH group showed anxious and depressive-like behavior in the EPM and FST tests, as well as increased levels of RS and decreased GSH levels in the hippocampus. Quercetin treatment in the GBH+Quer group allowed partial or total improvement in behavioral tests (EPM and FST) and in the levels of oxidative stress markers (RS and GSH). However, the quercetin group showed similar behavior to the GBH group after treatment. The results revealed that oral exposure to a subchronic low dose of GBH was capable of promoting effects on behavior and oxidative stress in the hippocampus of mice. In addition, despite quercetin having a neuroprotective role, caution is needed when considering the possible per se effects of its continuous supplementation.
显示更多 [+] 显示较少 [-]Laboratory experimental study of the evaporation and mechanical behaviour of deposited tailings 全文
2021
Zheng, Binbin | Wang, Jiahe | Zhang, Dongming | Zhao, Lei | Wang, Wensong
Surface deposition has been widely used in the mining industry to manage mill tailings. Tailings are generally discharged in the form of a slurry into tailings ponds. The slurried tailings are deposited in layers that undergo complex processes, e.g. evaporation, desiccation and consolidation. The evaporation of the deposited tailings controls their geotechnical engineering behaviour, which is necessary to characterise the physical properties. In this study, a constant temperature device was employed in evaporation tests to investigate two classes of deposited tailings, and the effects of the initial concentration, particle size, exposure area and deposited layer thickness on the evaporation processes were analysed. The test results showed four stages in the evaporation processes of deposited coarse and fine tailings. Dewatering of the deposited tailings occurred during the first two stages, which were keys to improving the desiccation efficiency of the tailings in the pond. The exposure area and deposited layer thickness also had a considerable influence on evaporation. The evaporation rate increased with the exposure area and layer thickness. Direct shear tests were performed to measure the shear strength of intact tailings during evaporation and used to determine the variation law of the mechanical properties of the test tailings.
显示更多 [+] 显示较少 [-]Enhanced activated persulfate oxidation of ciprofloxacin using a low-grade titanium ore under sunlight: influence of the irradiation source on its transformation products 全文
2021
Macías-Vargas, José-Alberto | Campos-Mañas, Marina Celia | Agüera, Ana | Sánchez Pérez, José Antonio | Ramírez-Zamora, Rosa-María
In this work, the activated persulfate oxidation of ciprofloxacin (CIP) using a low-grade titanium ore under sunlight or simulated sunlight were conducted to analyze the CIP degradation efficiency and to identify the transformation products (TPs) generated during oxidation under both types of irradiation sources by using liquid chromatography-quadrupole time-of-flight mass spectrometry (LC-QTOF-MS). All advance oxidation process experiments were performed in a 2700-mL raceway reactor at a pH value of ~ 6.5 and an initial CIP concentration of 1 mg/L, during 90 min of reaction time. The control experiments carried out under simulated sunlight achieved a 97.7 ± 0.6% degradation efficiency, using 385 W/m² of irradiation with an average temperature increase of 11.7 ± 0.6 °C. While, the experiments under sunlight reached a 91.2 ± 1.3% degradation efficiency, under an average irradiation value of 19.2 ± 0.3 W/m² in October–November 2019 at hours between 11:00 am and 3:00 pm with an average temperature increase of 1.4 ± 0.8 °C. Mass spectrometry results indicated that 14 of the 108 possible TPs reported in the literature were detected. The calculated exact mass, measured accurate mass, and its characteristic diagnostic fragment ions were listed, and two new TPs were tentative identified. The TP generation analysis showed that some specific compounds were detected in different time intervals with kinetic variations depending on the irradiation used. Consequently, two CIP degradation pathways were proposed, since the type of irradiation determines the CIP degradation mechanism. Graphical abstract
显示更多 [+] 显示较少 [-]Integrated risk prioritization and action selection for cold chain 全文
2021
Dagsuyu, Cansu | Derse, Onur | Oturakci, Murat
Cold chain, which affects human health and quality of life, is applied for temperature-sensitive and perishable products. Any problems occurring in the cold chain can cause deterioration in products, causing poisoning, death, or various diseases. There are many stages in the cold chain itself and the risk significance level of each stage is different. Therefore, the risks that occur depending on the weight of the stages in the cold chain should be defined and minimized and action plans are needed to be formed. Every action in the action plan cannot be implemented simultaneously since each action requires a different amount of budget and time resources of the companies are finite. Hence, the risks occurring in the cold chain should be minimized with the maximum use of limited company resources. In this study, an integrated mathematical model with analytical hierarchy method and failure mode and effect analysis is proposed that will maximize the weighted risk reduction amount by considering the budget and time constraints of the companies at the same time. The proposed approach has been applied in the 3PL service provider and the results are discussed. According to the results of the study where maximum benefit is aimed with the actions taken against the dangers, the maximum objective function value was obtained at the second and third levels of the workforce and budget values by evaluating the different situations with scenario analyses. In this solution, it is foreseen that by taking 5 actions, improvement will be made in 14 hazards.
显示更多 [+] 显示较少 [-]Comprehensive assessment of water quality and associated health risk by using physicochemical quality indices and multivariate analysis in Terme River, Turkey 全文
2021
Ustaoğlu, Fikret | Taş, Beyhan | Tepe, Yalçın | Topaldemir, Halim
The ecosystem and water quality of Terme River, an essential drinking and irrigation water source in the region, are at risk due to anthropogenic pressures. Therefore, the present study aim to present a comprehensive overview of the water quality state and pollution sources of the river. Some physicochemical water quality parameters were analyzed by standard methods along the surface water of river spatiotemporally. The concentrations of major elements and heavy metals (Na, Mg, K, Ca, Al, Cr, Fe, Co, Mn, Ni, Zn, Cd, Cu, Pb, As) were measured in water samples. Relationships between physicochemical data were assessed by using multivariate statistical analysis (MSA) methods. The order of the mean values of cations were as follow: Ca²⁺ > Mg²⁺ > Na⁺ > K⁺ > NH₄⁺ (32.66, 26.82, 13.29, 6.45, 0.305; mg/L), and order of anions: SO₄²⁻ > NO₃– >F⁻ > NO₂– (7.88, 3.988, 1.01, 0.0316; mg/L). Increases in ion concentrations in the downstream zone have been monitored in the summer and autumn months. Average water quality index (WQI) 22, heavy metal pollution index (HPI) 15.61, heavy metal evaluation index (HEI) 0.78, and nutrient pollution index (NPI) 0.404 values indicated that the general water quality of Terme River was fine. All hazard quotient (HQ) and hazard index (HI) values in this study were calculated below the risk threshold (<1). HI-total values (2.48E-01) in children were higher than in adults (2.14E-01). This suggests that children’s health is at higher risk than adults. Principal component analysis (PCA) data formed four principal components (PCs) explaining 85.22% of the total variance. These PCs revealed that the significant changes in water quality occurred from point and diffuse sources, including rock types of the basin, soil erosion, domestic wastewater discharges, and agricultural flow of inorganic fertilizers.
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