خيارات البحث
النتائج 3821 - 3830 من 7,291
Spatial distribution of antibiotic resistance genes of the Zaohe–Weihe Rivers, China: exerting a bottleneck in the hyporheic zone النص الكامل
2022
Shen, Siqi | Yang, Shengke | Zhang, Dan | Jia, Yang | Zhang, Fanfan | Wang, Yanhua | Wang, Wenke
The hyporheic zone (HZ) is an active biogeochemical region where groundwater and surface water mix and a potential reservoir for antibiotic resistance genes (ARGs). In this paper, the relative abundance and spatial distribution of ARGs in the HZ media were investigated, taking into consideration both the five speciation of six metals and the local characteristics. The samples of surface water, groundwater, and sediment were collected from Zaohe–Weihe Rivers of Xi’an City, which is a representative city with characteristics of the northwest region of China. Of 271 ARGs associated with 9 antibiotics, 228 ARGs were detected, with a total detection rate of 84%. Sulfonamide and aminoglycoside ARGs were the dominant types of ARGs. The top 6 ARGs and mobile genetic elements (MGEs) in terms of abundance were tnpA-04, cepA, sul1, aadA2-03, sul2 and intI1. The results of principal component analysis (PCA) showed that the distribution characteristics of ARGs were not associated with the sampling sites but with the environmental medias. Similarity in the water phases and significant differences in the water and sediment phases were found. The redundancy analysis (RDA) identified the key factors controlling ARG pollution, including dissolved oxygen (DO) in surface water, total nitrogen (TN) in groundwater, and total organic carbon (TOC) in sediment. In terms of the speciation of heavy metals, we further revealed the promotion effect between ARGs and heavy metals, especially the residual fraction of Ni. In terms of horizontal transfer mechanism, ARGs were significantly correlated with tnpA-03 in water phase and tnpA-04 in sediment. In the three media, intI1 and ARGs all show a significant correlation. These findings showed that hyporheic zone exerted a bottleneck effect on the distribution and transfer of ARGs.
اظهر المزيد [+] اقل [-]Comparative immunomodulatory efficacy of rosemary and fenugreek against Escherichia coli infection via suppression of inflammation and oxidative stress in broilers النص الكامل
2022
Farouk, Sameh M. | Abdel-Rahman, Haidy G. | Abdallah, Osama A. | EL-Behidy, Nashwa G.
Broiler chickens are frequently infected with Escherichia coli (E. coli) bacteria, which often leads to the emergence of many diseases and high economic losses. Hence, the current study was conducted to assess the relative efficacy of dietary rosemary and fenugreek, under E. coli infection in broilers and their ability to replace antimicrobials without any loss of productivity or negative influence on broiler health, via evaluation of growth performance, biochemical indices, immune response and histo-morphological changes. Eighty Cobb broilers were allotted to four equal groups (n = 20 chicks/group): control non-infected (CN), control infected (CI), rosemary infected (RI) and fenugreek infected (FI) groups. The RI and FI groups revealed a significant elevation in their body weight and body weight gain compared with the CI group. However, both groups showed a significant decline in serum aspartate and alanine aminotransferase activities, as well as uric acid and creatinine levels. A significant decrease in total antioxidant capacity, catalase and superoxide dismutase activities was noted among CI chicks. Moreover, distinctly higher activities were evident in both RI and FI groups. Assessment of immunomodulatory markers showed a significant increase in immunoglobulin G along with a significant decline in interleukin-6 level in both RI and FI groups, with the lowest IL-6 value within FI group. Histopathological evaluations focused on the deleterious effect associated with E. coli infection of broilers’ liver, kidney, intestine, spleen, bursa of Fabricius and thymus. Partial histological improvement was noticed among RI group, and nearly normal tissues were recorded in FI group. Overall, the obtained findings suggest the ability of fenugreek to mitigate the adverse effects of E. coli infection on broiler performance and tissue profiles, by improving the general health status of the broiler chickens.
اظهر المزيد [+] اقل [-]Particular pollutants, physical properties, and environmental performance of porous ceramsite materials containing oil-based drilling cuttings residues النص الكامل
2022
Xiong, Deming | Wang, Chaoqiang | Huang, Xin
The mineral compositions of oil-based drilling cutting residues (ODCRs) were similar to that of clay, which could be used as raw materials for ceramsite. In this study, the maximum addition of ODCRs and the optimum calcination conditions were studied by single factor experiment. The microstructure, phase composition, and element distribution of ceramsite were studied by means of SEM, XRD and EDS. The ceramsite, with a 40% ODCRs content, was calcined at 1000 °C for 2 h. After cooling down, the ceramsite had good physical properties, including low density, low water absorption, and high compressive strength. The bulk density was 850–970 kg/m³, the water absorption was 2.1–10%, and the cylinder compressive strength was 6–11.8 MPa. And most of the heavy metals in ODCRs were effectively solidified. The organic toxic substances were completely burned. The leaching amount of harmful elements met the requirements of Chinese standards. The ceramsite would avoid secondary pollution to the environment. So the ceramsite made from ODCRs can not only improve the processing speed of ODCRs, but also be used as building materials, greening materials, industrial filter materials, etc., and increase its environmental and social benefits.
اظهر المزيد [+] اقل [-]Bibliometric analysis of global research progress on electrochemical degradation of organic pollutants النص الكامل
2022
Dos Santos, José Ribamar Nascimento | Alves, Ismael Carlos Braga | Marques, Aldaléa Lopes Brandes | Marques, Edmar Pereira
As a result of anthropogenic action, an increasing amount of toxic organic compounds has been released into the environment. These pollutants have adverse effects on human health and wildlife, which has motivated the development of different types of technologies for the treatment of effluents and contaminated environments. The electrochemical degradation of organic pollutants has attracted the interest of research centers around the world for its environmental compatibility, high efficiency, and affordable cost. In the present study, a bibliometric analysis was performed using the Web of Science database in order to assess the progress of publications related to electrochemical degradation of organic pollutants between the years 2001 and 2021. The data retrieved showed a significant increase in publications related to the topic in the last 20 years. Electrochimica Acta was the magazine responsible for the largest number of publications (291, 6.52%). The studies mainly included the areas of engineering, chemistry, and environmental science ecology. China with a total of 1472 (32.96%) publications dominated research in this area, followed by Spain (436, 9.76%) and Brazil (345, 7.72%). The institutions with the highest number of contributions were the University of Barcelona and the Chinese Academy of Sciences, and the most productive authors were Brillas E. and Oturan M. A. The results of this study provide important references and information on possible research directions for future investigations on electrochemical degradation of organic pollutants.
اظهر المزيد [+] اقل [-]Spatial Spillover Effects of Renewable Energy on Carbon Emissions in Less-developed Areas of China النص الكامل
2022
Bai, Jun | Li, Shixiang | Kang, Qiying | Wang, Nan | Guo, Kailu | Wang, Jinfeng | Cheng, Jinhua
The purpose of this paper is to determine the spatial spillover effects of renewable energy on carbon emissions in China’s less-developed areas. However, few studies have considered this issue from the perspective of less-developed areas. Based on panel data of 21 provinces in China from 2000 to 2017, this paper analyzes the spatial spillover effects of renewable energy on carbon emissions using Moran’s I and Spatial Durbin Model (SDM). The results suggest that, first, Moran’s I ranges from 0.378 to 0.519, Moran scatter plot presents that provinces are located in the high–high (HH) and low-low (LL) quadrants, indicating provincial carbon emissions in the study area have a significant spatial correlation and agglomeration. Second, under the three matrices, the direct effect coefficients of renewable energy are -0.2522, -0.2639 and -0.2601, this shows that renewable energy is beneficial to local carbon emissions reduction. In contrast, the indirect effect coefficients of renewable energy are 0.0605, 0.1012 and 0.1125, which means higher renewable energy consumption in a single area is conducive to the improvement of carbon emissions to neighbouring areas. Third, urbanization, industrialization, physical capital and other variables have different impacts on local and nearby carbon emissions. This study provides empirical evidence to achieve carbon emission reduction targets by government policymakers.
اظهر المزيد [+] اقل [-]Characteristics of antibiotic resistance genes in full-scale anaerobic digesters of food waste and the effects of application of biogas slurry on soil antibiotic resistance genes النص الكامل
2022
Wang, Pan | Zheng, Yi | Lin, Peiru | Chen, Xiteng | Qi, Linsong | Yang, Xinyu | Ren, Lianhai
The fate of antibiotic resistance genes (ARGs) in full-scale anaerobic digestion (AD) of food waste (FW) and in the soil applied with biogas slurry has not been fully understood. In this study, 12 targeted ARGs and intI1 in FW, intermediate product, and biogas slurry from three full-scale AD were analyzed. The results showed that subcritical water pretreatment was an effective method for ARG attenuation, by which the absolute abundance of total targeted ARGs was removed by 99.69%. The predominant ARGs (ermB, tetM, and tetW) in FW were removed more than 99% after subcritical water pretreatment. The result of field experiments with biogas slurry as fertilizer showed that the absolute abundance of several ARGs (sul2, tetM, blaOXA-1, blaTEM) and intI1 accumulated significantly compared to the control group (CK) during three consecutive growth stages of the rice. The detected abundance of ARGs in paddy field soil increased from 190.50 (CK) to 8.87 × 10⁴ copies/g (wet weight) (soil) during tillering stage, and increased from 4102.65 (CK) to 4.38 × 10⁴ copies/g (wet weight) (soil) during heading time. Biogas slurry improved the soil nutrients (TN, AN, TP, and AP); meanwhile, the concentrations of total salt and Cl⁻ increased. Network analysis indicated that 28 genera were the possible hosts of ARGs; variation partitioning analysis (VPA) indicated that microbial communities (contribution 59.30%) were the main factors that affected the fate of ARGs and intI1.
اظهر المزيد [+] اقل [-]Ag3PO4-based photocatalysts and their application in organic-polluted wastewater treatment النص الكامل
2022
Yu, Chunmu | Chen, Xiaojuan | Li, Ning | Zhang, Yue | Li, Sailin | Chen, Jieming | Yao, Liang | Lin, Kaichun | Lai, Yiqi | Deng, Xinru
Semiconductor photocatalysis technology has shown great potential in the field of organic pollutant removal, as it can use clean and pollution-free solar energy as driving force. The discovery of silver phosphate (Ag₃PO₄) is a major breakthrough in the field of visible light responsive semiconductor photocatalysis due to its robust capacity to absorb visible light < 520 nm. Furthermore, the holes produced in Ag₃PO₄ under light excitation possess a strong oxidation ability. However, the strong oxidation activity of Ag₃PO₄ is only achieved in the presence of electron sacrifice agents. Otherwise, photocorrosion would greatly reduce the reuse efficiency of Ag₃PO₄. This review thus focuses on the structural characteristics and preparation methods of Ag₃PO₄. Particularly, the recent advances in noble metal deposition, ion doping, and semiconductor coupling, as well as methods of magnetic composite modification for the improvement of catalytic activity and recycling efficiency of Ag₃PO₄-based catalysts, were also discussed, and all of these measures could enhance the catalytic performance of Ag₃PO₄ toward organic pollutants degradation. Additionally, some potential modification methods for Ag₃PO₄ were also proposed. This review thus provides insights into the advantages and disadvantages of the application of Ag₃PO₄ in the field of photocatalysis, clarifies the photocorrosion essence of Ag₃PO₄, and reveals the means to improve photocatalytic activity and stability of Ag₃PO₄. Furthermore, it provides a theoretical and methodological basis for studying Ag₃PO₄-based photocatalyst and also compiles valuable information regarding the photocatalytic treatment of organic polluted wastewater.
اظهر المزيد [+] اقل [-]Evaluation of metal contamination, flux and the associated human health risk from atmospheric dustfall in metal mining areas of Southern Jharkhand, India النص الكامل
2022
Mahato, Mukesh Kumar | Singh, Abhay Kumar | Giri, Soma
Metals can be apprehended in the atmospheric environment of copper and iron mining areas of Jharkhand, which falls in one of the most mineralized areas of India with extensive mining and industrial activities. The study was taken up to appraise the metal contamination in the atmospheric dust to evaluate the metal fluxes and associated health risk considering the seasonal variations. Sixty samples were analyzed for As, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, and Zn using the inductively coupled plasma mass spectrometer (ICP-MS) and the contamination levels were assessed by various indices. The metal content of dustfall samples exceeded the average shale values for most of the metals. Higher metal concentrations were found in the locations in close vicinity of mining and industrial areas. The principal component analysis suggested both geogenic and anthropogenic sources for metals in the atmospheric dustfall. Human health risk as determined by hazard quotient (HQ) and hazard index (HI) suggested considerable risk to the child populace through the ingestion pathway for both the mining areas, higher being in iron mining areas. The metal flux and the health risk were higher in summers as compared to winters for both the mining areas. Consequently, the results advocate the necessity of periodic monitoring of the freefall dust of the mining areas and development of proper management strategies to reduce the metal pollution.
اظهر المزيد [+] اقل [-]Geotechnical properties of oil-polluted soil: a review النص الكامل
2022
Haghsheno, Hamed | Arabani, Mahyar
Soil polluted by oil and its derivatives is a critical environmental issue worldwide that jeopardizes ecological systems and causes geotechnical problems. This review paper focuses on the previous studies concerning the impacts of oil pollution on soil geotechnical properties. To this end, related academic literature on this topic was investigated and discussed. The findings of this study demonstrated that the addition of oil pollution in coarse-grained soils significantly reduces particle surface roughness. On the other hand, in fine-grained soils, it results in flocculation and secondary aggregation of clay particles, less aggregated and loose packing in the soil matrix, the formation of isometric pores, the formation of fissure-like pores, and an increase in mesoporosity. In general, it was found that the geotechnical properties of oil-polluted soils are mostly determined by the physicochemical and/or physical interactions between the soil and contaminant. Additionally, previous research has demonstrated that oil pollutants alter the geotechnical properties of cohesive and non-cohesive soils significantly, including the Atterberg limits, particle-size distribution, compaction behavior, unconfined compressive strength, friction angle, cohesion, hydraulic conductivity, and consolidation characteristics. However, no general pattern could be established for the majority of them. Besides, it was found that the degree of geotechnical property alteration of oil-polluted soil is strongly influenced by the soil type and features, as well as the quantity, type, and chemical composition of oil pollutants.
اظهر المزيد [+] اقل [-]Preventable mortality attributable to exposure to air pollution at the rural district of Punjab, India النص الكامل
2022
Ravindra, Khaiwal | Singh, Tanbir | Mor, Suman
Air pollution has emerged as a leading global health risk in recent decades, where its health impacts are primarily focused on urban areas. In India, semi-urban and rural areas are also emerging as air pollution hotspots. As these regions are out of focus, the current study monitored air pollution (PM₂.₅) at a rural district of Punjab in North India and attempted to study the associated health impacts. Hospital data of outpatient department (OPD), inpatient department (IPD) and all-cause mortality was correlated with change in PM₂.₅ concentrations. PM₂.₅ concentrations showed seasonal variations having relatively higher concentrations during post-monsoon and winter seasons. This rise in air pollution (annual average 92 µg/m³) was found to be mainly due to crop residue burning, including local meteorology. In comparison, hospital data shows that hospital visits and admissions were higher during monsoon. This shows that hospital admissions could not be directly linked to air pollution in rural areas as other factors such as short days during winters and self-medication, socio-economic factors and dependency on local unauthorised traditional healers may influence. The application of the AirQ + model for short-term health effects reveals that out of 2582 total deaths, preventable deaths ranging from 246 (WHO guidelines value – 10 µg/m³) to 159 (Indian NAAQS – 40 µg/m³) could be ascribed to air pollution exposure and specifically PM₂.₅. However, these deaths are avoidable by developing strategies to minimise air pollution in rural areas. Hence, a comprehensive approach is needed to plan air pollution reduction strategies, including urban, semi-urban and rural areas.
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