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Результаты 4001-4010 из 6,560
Spatio-temporal variation and risk assessment of hydrochemical indices in a large diversion project of the Yellow River, northern China, from 2008 to 2017 Полный текст
2020
Li, Yuan | Wang, Fei | Feng, Jia | Lv, Junping | Liu, Qi | Nan, Fangru | Liu, Xudong | Xu, Lan | Xie, Shulian
Large-scale, inter-basin water diversion projects have been developed to relieve water scarcity crisis and water pollution problems. Environmental status and ecosystem impacts are largely unknown for the Wanjiazhai Yellow River Diversion Project (YRDP-WJZ), a water body critical in northern China. In the current study, twelve hydrochemical indices (including Mn, Cu, Zn, Hg, Pb, NH₃-N, COD-Mn, DO, BOD₅, COD, TP, and TN) were collected from 2008 to 2017 based on multiple analytical approaches to understand environmental status and ecological risks. Human health risk and threats to aquatic organisms from heavy metals were assessed. Heavy metals have no regular spatial distribution. Biochemical parameters and nutrients pollute seriously in midstream and downstream, respectively. Hydrochemical indices suggested high levels of pollution in the midstream section. Water quality improved downstream of the Fenhe Reservoir, but total nitrogen and total phosphorus in the downstream section increased in recent years. The Canadian Council of Ministers of the Environment Water Quality Index (CWQI) suggested midstream water quality was poor in general, and 80% of annual calculations had a marginal grade. For aquatic organisms, ecological risks of Cu and Zn were high. For local residents, drinking water was generally safe, but continued monitoring is critical due to ongoing threats to water quality in these areas.
Показать больше [+] Меньше [-]Analyzing extended STIRPAT model of urbanization and CO2 emissions in Asian countries Полный текст
2020
Naushīn, Miṣbāḥ | Abbasi, Muhammad Ali | Iqbāl, Jāvīd
CO₂ emissions tend to increase more rapidly in underdeveloped economies as compared to developed countries mainly in China, India, and Asia. One of the aspects that accounts for the increasing CO₂ emissions is urbanization (UR) and it is increasing all over the world particularly in Asian and African regions. The present study examines the impact of energy use and UR on carbon emissions over the period 1995 to 2018 while using the extended STIRPAT model for Asian countries. Panel co-integration techniques and Granger causality test are applied on selected variables. FMOLS and DOLS methods are also applied to check for robustness. Findings confirm the presence of long-run co-integration among variables. The outcomes propose that energy consumption and UR have positive impact on CO₂ emissions and output. Outcomes also reveal that financial development (FD) has negative effect on emissions of CO₂ but positive effect on economic growth. Results of Granger causality technique indicate that long-run causality association exists among emissions of CO₂, economic growth, and UR. In the short run (SR), bidirectional causal relationship has been found between trade openness and FD.
Показать больше [+] Меньше [-]Effects of microplastics and nanoplastics on marine environment and human health Полный текст
2020
Sana, Siva Sankar | Dogiparthi, Lakshman Kumar | Gangadhar, Lekshmi | Chakravorty, Arghya | Abhishek, Nalluri
Microplastics (MPs) with an average size of less than 5 mm, along with nanoplastics (NPs) of an average size of fewer than 0.1 μm are the result of huge plastic waste fragmentation or straight environmental emissions. Pollution from micro- and nanoplastics is a worldwide paradigm that raises environmental and human health concerns. They may also comprise very harmful chemicals that are implemented in plants and animals when MPs/NPs are used that may lead to higher accumulation of these compounds in food chains. In addition, higher surface area-to-volume ratio, characteristic of MPs/NPs can contribute to their potentially harmful impact as other pollutants, like continuous organic contaminants, can also be bio-accumulated and adsorbed. A complex issue correlated with MPs/NPs is their ability to absorb and interact with other common pollutants in the environment, such as metals, pharmaceuticals, and other contaminants. Thus, MPs/NPs can directly influence on destiny and toxicity of these substances to the environment and organisms. In this review, first, we introduce possible sources and formation, their destinies, and environmental impact of MPs/NPs and then explain feasible paths of all these particles entering the human body. Then, the review highlights the effect of MPs/NPs on human health. Finally, it provides a brief summary of the potential as well as the neurological toxicity of MPs/NPs.
Показать больше [+] Меньше [-]Genetic polymorphisms in XRCC1, OGG1, and XRCC3 DNA repair genes and DNA damage in radiotherapy workers Полный текст
2020
Soliman, Asmaa H. M. | Zaki, Nasef N. | Fathy, Hala M. | Mohamed, Aml A. | Ezzat, Mohamed A. | Rayan, Amal
DNA damage may develop at any dose of ionizing radiation. DNA damage activates pathways that regulate cell growth and division or coordinate its replication and repair. The repair pathways, base excision repair (BER) and single-strand break repair (SSBR), can repair such damages efficiently and maintain genome integrity. Loss of this repair process or alteration of its control will be associated with serious outcomes for cells and individuals. This study aimed to determine the relationship between XRCC1 (Arg194Trp, Arg280His, and Arg399Gln), OGG1 (Ser326Cys), and XRCC3 (Thr241Met) SNPs and DNA damage and to identify high-risk individuals with reduced DNA repair capacity. This case-control study was conducted on 80 subjects; 50 subjects working in Clinical Oncology and Nuclear Medicine Department in Assiut University Hospital along with 30 controls. A total of 1 mL blood samples were collected for Single-Cell Gel Electrophoresis Technique (Comet Assay) for detection of DNA damage in those subjects. A total of 3 mL fresh blood samples were collected and analyzed by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP)–based technique. DNA damage detected by comet test was significantly high in IR-exposed workers than control. Statistically high significant difference was found in exposed subjects versus control subjects regarding the frequencies of the variant alleles of hOGG1³²⁶, XRCC1²⁸⁰ & ³⁹⁹, and XRCC3²⁴¹. The level of DNA damage was not affected by OGG1³²⁶ SNPs when comparing subjects of wild genotype with those of (pooled) variants either in the exposed staff or in the control group while XRCC1²⁸⁰, ³⁹⁹ and XRCC3²⁴¹ variant alleles had an influence on the studied DNA damage biomarker. Moreover, genotyping distribution pattern was highly variable in relation to gender. The present study indicated a relationship between DNA damage detected by comet test and single nucleotide polymorphisms in genes coding for DNA certain repair enzymes. Individuals occupationally exposed to low doses of ionizing radiation could be at great risk and more susceptible to the increased DNA damage if they have inherited genetic polymorphism.
Показать больше [+] Меньше [-]Production of sulphides in denitrifying woodchip bioreactors Полный текст
2020
Malá, Jitka | Hrich, Karel | Schrimpelová, Kateřina | Bílková, Zuzana
Denitrifying woodchip bioreactors, natural treatment systems used for the reduction of nitrates in agricultural runoff or groundwater, may cause adverse side effects within receiving waters. One of the least studied but nonetheless still serious issues is the production of hydrogen sulphide, which occurs in bioreactors under operating conditions favourable to its creation. The aim of this paper is to elucidate the effect of process parameters on the production of sulphides and the proportion of hydrogen sulphide in a 1-year-long experimental study with four laboratory-scale denitrifying bioreactors. During the study, the strong dependence of sulphate reduction and the production of sulphides on the effluent oxidation-reduction potential (ORP) and nitrate-nitrogen (NO₃-N) concentrations of bioreactors became evident. Sulphide formation occurred at concurrent effluent NO₃-N concentrations below 3 mg/L and ORPs lower than − 100 mV. The tested hydraulic retention time of 1.7 days was sufficiently long to achieve these conditions. At an effluent pH of 7 or lower, the majority of the total sulphides present were in the form of hydrogen sulphide. It is suggested that in order to avoid the production of hydrogen sulphide, the production of total sulphides has to be minimised.
Показать больше [+] Меньше [-]Astragaloside protects rat brain from microwave-induced functional injuries via restoring acetylcholine and normalizing electroencephalogram Полный текст
2020
Zhao, Li | Sun, Yunbo | Yu, Chao | Chen, Junjun | Xu, Xinping | Zhang, Xueyan | Wang, Hui | Zhang, Jing | Wang, Haoyu | Dong, Ji | Yao, Binwei | Zhou, Hongmei | Liu, Shuchen | Peng, Ruiyun
Studies from our group and others have reported that 30 mW/cm² microwave could damage the structures of rat hippocampus, as well as impair the neuronal functions. The neuroprotective effects of astragaloside, purified from Astragalus membranaceus, have been demonstrated in animal models of neurodegenerative diseases. In this study, we found that 30 mW/cm² microwave impaired spatial learning and memory ability in rats, while astragaloside could significantly alleviate the injuries. The pathological analysis also showed that astragaloside protected neurons from microwave-induced damages, such as mitochondrial swelling and cavitation, rough endoplasmic reticulum swelling and dilation, synaptic gap disappearing, and vesicle aggregation. Moreover, microwave-induced structural damage of synapse resulted in downregulation of acetylcholine, an important neurotransmitter for information transmission, while astragaloside could protect the structure of synapse, as well as restore the acetylcholine level in rat hippocampus. Furthermore, astragaloside also accelerated the recovery of brain electroencephalogram (EEG) after microwave exposure, indicating that astragaloside could promote the normalization of neuronal functions. In conclusion, astragaloside protected the morphological structures and restored acetylcholine level in rat hippocampus, which could improve brain functions via normalizing brain EEG. Therefore, astragaloside might be a promising candidate to treat microwave-induced injuries of central nervous system (CNS).
Показать больше [+] Меньше [-]Zn/Pb Concentration Ratios Emphasize Spatiotemporal Airborne Metal Dynamics in Soils Under Different Land Use Полный текст
2020
van Oort, Folkert | Monna, Fabrice | Garnier, Stéphane
Zinc (Zn) and lead (Pb) concentrations were measured in 173 samples collected in soils under forest, wetland, and arable land around a Zn smelter plant that stopped activity in the 1960s. The adopted sampling strategy consisted in collecting 0–30-cm-depth samples from all soils, tilled or not, in order to harmonize the analyzed soil volume to that of plowed soils. Airborne deposition was modeled as a function of the distance from the pollution source and of land use. The Zn/Pb concentration ratios in the surface layer remarkably contrasted 3–4, 1.5–2, and ~ 0.5 for arable, wetland, and forest soils, respectively, independently from the distance to the emission source, while total Zn and Pb concentrations, taken separately, were only slightly discriminant. For metal pollution sites originating from former industrial activity, Zn/Pb concentration ratios determined on relevant soil samples represent a powerful indicator that provides easy and rapid information in real field conditions on time-related input/output dynamics of mobile and less-mobile metal pollutants, and hence, on interactions between pollutants and soils under different land use conditions.
Показать больше [+] Меньше [-]Investigating the potential use of an oleaginous bacterium, Rhodococcus opacus PD630, for nano-TiO2 remediation Полный текст
2020
Sundararaghavan, Archanaa | Mukherjee, Amitava | Suraishkumar, Gadi K.
The occurrence of titanium dioxide nanoparticles (nTiO₂), in the effluents released from wastewater treatment plants, has raised concerns. The fate of nTiO₂ and their potential impact on organisms from different ecosystems are widely investigated. For the first time, in this work, we report the responses of an oleaginous bacteria Rhodococcus opacus PD630, belonging to an ecologically important genus Rhodococcus to environmentally relevant concentrations of nTiO₂, under dark and UV light conditions. We observed a dose-dependent increase in nTiO₂ uptake by the bacteria that reached a maximum of 1.4 mg nTiO₂ (g cell)⁻¹ under mid-log UV exposure, corresponding to 97% uptake. The nTiO₂ induced oxidative stress in bacteria that increased from 25.1 to a maximum of 100.3, 44.1, and 51.7 μmol .OH (g cell)⁻¹ under dark, continuous, and mid-log UV, respectively. However, nTiO₂ did not affect bacterial viability. Further, due to oxidative stress, the triacylglycerol (biodiesel) content from bacteria increased from 30% to a maximum of 54% CDW. Based on our findings, we propose an application of R. opacus PD 630 in nTiO₂ remediation due to their high nTiO₂ uptake and resistance.
Показать больше [+] Меньше [-]Screening of agricultural land productivity and returning farmland to forest area for sensitivity to rural labor outward migration in the ecologically fragile Loess Plateau region Полный текст
2020
Li, Linfei | Khan, Sufyan Ullah | Xia, Xianli | Zhang, Huili | Guo, Chenhao
The mechanism of the non-agricultural transfer of rural labor to agricultural production efficiency and their interrelationships is a problem worthy of further discussion at this stage in China. The mediating effect model is constructed, the least square method is used for regression, and the instrumental variable method is used to solve the possible endogeneity problem. Through the investigation of farmers in Loess Plateau region, this paper analyzes the effects of factor substitution and planting structure adjustment after agricultural labors work outside and its impact on agricultural land output from the theoretical and empirical aspects, as well as the impact of off-farm employment on agricultural land output under different constraints. Results showed that the negative influence of labor non-agricultural transfer on farmland land output rate is − 7.264, and farmers’ participation in returning farmland to forests can alleviate the negative impact of non-agricultural transfer on the agricultural land output. Labor substitution factor investment plays a part in the mediating effect, and part of the mediating effect is − 0.879. The adjustment of agricultural planting structure plays the whole mediating effect, that is to say, the larger the scale of labor non-agricultural transfer in Loess Plateau area, the more unfavorable for farmers to invest in labor substitution agricultural factors of production, and the more they are inclined to grow food crops. When the constraint conditions of factor substitution difficulty and planting structure adjustment space are considered, the higher the factor substitution difficulty is, the smaller the planting structure adjustment space; the negative effect of the non-agricultural transfer of labor on the agricultural land output rate is more obvious. It provides effective reference value to judge the development stage and trend of regional agriculture and puts forward relevant policy suggestions to guarantee the development of regional agriculture and farmers’ life.
Показать больше [+] Меньше [-]Optimized methods for diffusive greenhouse gas flux analyses in inland waters Полный текст
2020
Zhu, Lin | Yu, Jianghua | Van Dam, Bryce | Cao, Huayong | Pu, Yinyu | Shi, Wenqing | Qin, Boqiang
Inland waters are considered hotspots of greenhouse gas (GHG) emissions and have been extensively researched. Static chamber (STAT) and thin boundary layer (BLE) are two commonly used methods for analyzing diffusive GHG emissions from inland waters. However, the STAT method is often disturbed by GHG bubbles; meanwhile, many kinds of headspace gas are used in the BLE method, but the differences between their diffusive GHG emission analysis results are not understood. In this study, the chamber in the STAT method was modified to combat the disturbances from GHG bubbles, and the typically used gases for the BLE method, namely, pure nitrogen, air, and filtered air, were comparatively studied. Results demonstrated that the modified chamber could effectively prevent the invasion of GHG bubbles; it increased the success rate from 67 to 90% in the field test, with no obvious impacts on the results of the GHG emission analyses. The use of air and filtered air in the BLE method yielded the lower values of GHG emissions relative to pure nitrogen, and this finding was potentially attributed to the inhibition effects of the residual GHGs and high humidity in air and filtered air on the extraction of diffusive GHGs from the surface water. This study improved the commonly used methods for diffusive GHG emission analysis, and the current findings are beneficial to the study of GHG emissions from inland waters.
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