خيارات البحث
النتائج 2131 - 2140 من 4,896
Influence of electronic cigarette vaping on the composition of indoor organic pollutants, particles, and exhaled breath of bystanders
2019
van Drooge, Barend L. | Marco, Esther | Perez, Noemi | Grimalt, Joan O.
The changes of particles and organic pollutants in indoor atmospheres as consequence of vaping with electronic cigarettes have been analyzed. Changes in the composition of volatile organic compounds (VOCs) in exhaled breath of non-smoking volunteers present in the vaping environments have also been studied. The exposure experiments involved non-vaping (n = 5) and vaping (n = 5) volunteers staying 12 h together in a room (54 m²) without external ventilation. The same experiment was repeated without vaping for comparison. Changes in the distributions of particles in the 8–400 nm range were observed, involving losses of nucleation-mode particles (below 20 nm) and increases of coagulation processes leading to larger size particles. In quantitative terms, vaping involved doubling the indoor concentrations of particles smaller than 10 μm, 5 μm, and 1 μm observed during no vaping. The increase of particle mass concentrations was probably produced from bulk ingredients of the e-liquid exhaled by the e-cigarette users. Black carbon concentrations in the indoor and outdoor air were similar in the presence and absence of electronic cigarette emissions. Changes in the qualitative composition of PAHs were observed when comparing vaping and non-vaping days. The nicotine concentrations were examined separately in the gas and in the particulate phases showing that most of the differences between both days were recorded in the former. The particulate phase should therefore be included in nicotine monitoring during vaping (and smoking). The concentration increases of nicotine and formaldehyde were small when compared with those described in other studies of indoor atmospheres or health regulatory thresholds. No significant changes were observed when comparing the concentrations of exhaled breath in vaping and no vaping days. Even the exhaled breath nicotine concentrations in both conditions were similar. As expected, toluene, xylenes, benzene, ethylbenzene, and naphthalene did not show increases in the vaping days since combustion was not involved.
اظهر المزيد [+] اقل [-]Ambient air pollution and risk of type 2 diabetes in the Chinese
2019
Li, Hui | Duan, Donghui | Xu, Jiaying | Feng, Xiaoqi | Astell-Burt, Thomas | He, Tianfeng | Xu, Guodong | Zhao, Jinshun | Zhang, Lina | You, Dingyun | Han, Liyuan
We performed a time series analysis to investigate the potential association between exposure to ambient air pollution and type 2 diabetes (T2D) incidence in the Chinese population. Monthly time series data between 2008 and 2015 on ambient air pollutants and incident T2D (N = 25,130) were obtained from the Environment Monitoring Center of Ningbo and the Chronic Disease Surveillance System of Ningbo. Relative risks (RRs) and 95% confidence intervals (95% CIs) of incident T2D per 10 μg/m³ increases in ambient air pollutants were estimated from Poisson generalized additive models. Exposure to particulate matter < 10 μm (PM₁₀) and sulfur dioxide (SO₂) was associated with increased T2D incidence. The relative risks (RRs) of each increment in 10 μg/m³ of PM₁₀ and SO₂ were 1.62 (95% CI, 1.16–2.28) and 1.63 (95% CI, 1.12–2.38) for overall participants, whereas for ozone (O₃) exposure, the RRs were 0.78 (95% CI, 0.68–0.90) for overall participants, 0.78 (95% CI, 0.69–0.90) for males, and 0.78 (95% CI, 0.67–0.91) for females, respectively. Exposure to PM₁₀ and SO₂ is positively associated with T2D incidence, whereas O₃ is negatively associated with T2D incidence.
اظهر المزيد [+] اقل [-]Sorption of Copper and Zinc from Aqueous Solution by Metabasalt Residue and its Mineralogical Behavior
2019
Dalacorte, Luana | Escosteguy, Pedro Alexandre Varella | Bortoluzzi, Edson Campanhola
Residues from mining, as metabasalt powder from amethyst exploration, can be used to improve soil properties. Although there is a high-load content of clay minerals in metabasalt, the effects of this residue on cooper (Cu²⁺) and zinc (Zn²⁺) sorption and desorption have not been studied. The aim of this work was to evaluate Cu²⁺ and Zn²⁺ sorption capacity of metabasalt powder and to discuss the mineralogical behavior facing this phenomenon. This residue sorption capacity was compared to reference clay minerals under two Cu²⁺ and Zn²⁺ concentrations (8 and 16 cmolc/kg) in a competitive system (Cu²⁺ + Zn²⁺). The sorption capacity was estimated by sequential desorption using cation exchange resin. A survey of mineralogical and Cu²⁺ and Zn²⁺ concentrations was performed on metabasalt before and after sorption, and after desorption tests. All materials sorbed higher amounts of Cu²⁺ than Zn²⁺. The sorption magnitude decreased in the following order: metabasalt > montmorillonite > illite > kaolinite. Cu²⁺ and Zn²⁺ desorption from metabasalt is lower than the standard clay minerals, since the metabasalt sorption sites are expandable interlayers of clay minerals. The relevance and application of our findings are critical in providing information for the management of metabasalt residue, suggesting potential use as a remediation agent in contaminated water, especially those with high Cu²⁺ and Zn²⁺ loading. It also suggests that the Cu²⁺ and Zn²⁺ enrichment of this residue could potentially be used for converting the metabasalt into a useful source of slow nutrient supply for agricultural soils.
اظهر المزيد [+] اقل [-]Antecedents of satisfaction and engagement of low-carbon bicycle-sharing using in China
2019
Ding, Xiping | Long, Xingle | Li, Liang | Liang, Hui | Wang, Qingling | Cai, Sijia
Transport sector contributed numerous carbon emissions in China. It is important to promote low-carbon bicycle-sharing using in China. This paper aims to analyze the influencing factors of the satisfaction and engagement of bicycle-sharing in China. An extended model of customer satisfaction is established, which considers both customer satisfaction theory and customer engagement theory. We explore the different effect of convenience, health, safety, and facility on satisfaction of bicycle-sharing using. We also explore the role of satisfaction on three different dimensions of engagement: enthusiasm, participation, and social interaction. Multi-group structure equation model is employed to explore the different roles of gender on the determinants of satisfaction and engagement of bicycle-sharing using. The findings reveal that facilities had the larger effect on satisfaction of bicycle-sharing using than safety and health for male. Safety had the largest influence on satisfaction of bicycle-sharing using for female, followed by facility, convenience, and health.
اظهر المزيد [+] اقل [-]Comparison of Biological Nutrient Removal via Two Biosorption-Activated Media Between Laboratory-Scale and Field-Scale Linear Ditch for Stormwater and Groundwater Co-treatment
2019
Chang, Ni-Bin | Wen, Dan | Colona, William | Wanielista, Martin P.
Excess nitrogen in the ecosystem could result in eutrophication and harmful algal bloom in an ecosystem. Low impact development (LID) facilities, regarded as an integral part of green infrastructures for flow control and water quality management may include, but are not limited to, dry/wet ponds, green roof, bioswale or linear ditch, vegetated natural strip, exfiltration trench, piping networks with underdrain or reuse options, and bioswale. This study presents a new approach using a linear ditch along a roadside for LID with the aid of two green sorption media that are designed for co-treatment of stormwater and groundwater for nutrient removal. The stormwater is primarily from agricultural discharge and transportation stormwater runoff. Two recipes of green sorption media, including the green sorption media and woodchip, were examined and compared through a laboratory-scale column study and a field-scale test bed media under various influent concentrations and flow conditions. The green sorption media were found more appropriate than the woodchip media for field-scale applications because the green sorption media may exhibit long-standing microenvironments and hydraulic patterns to provide a homogeneous hydraulic retention time and infiltration rate for nutrient removal. Therefore, such a new LID practice may not only mitigate the impact from various surface stormwater runoffs but also co-treat groundwater and stormwater for nutrient removal.
اظهر المزيد [+] اقل [-]From Saprotrophic to Clear Water Status: the Restoration Path of a Degraded Urban Lake
2019
Grochowska, Jolanta | Augustyniak, Renata | Łopata, Michał | Parszuto, Katarzyna | Tandyrak, Renata | Płachta, Anna
The study was conducted on Długie Lake in Olsztyn, which for 20 years since the mid-1950s served as a domestic and storm wastewater receiver, which led to its complete degradation. The discontinuation of wastewater inflow in 1976 caused a change in the trophic state from saprotrophic to hypertrophic. Evident improvement of water quality was possible only after the implementation of proper restoration techniques. Długie Lake was subjected to artificial aeration with thermal destratification (1987–2000). After all opportunities to improve water quality in the lake by artificial aeration (low phosphorus sorption capacity of sediment) had been exhausted, it was decided that a phosphorus inactivation method using the coagulant PAX 18 be used (2001–2003). Before restoration, the nutrient concentration in the near-bottom water layer of Długie Lake was very high at 22.9 mg TN L⁻¹ and 3.50 mg TP L⁻¹. The average amount of chlorophyll a was ca. 200 μg L⁻¹, and the Secchi disc visibility did not exceed 1 m. In 2017, 14 years after termination of the lake restoration process, the total phosphorus concentration at the bottom was 0.21 mg P L⁻¹ on average, and the total nitrogen was 1.5 mg N L⁻¹. The mean transparency of the water oscillated around approximately 5 m, and the amount of chlorophyll a was 1.86 μg L⁻¹. Studies have shown that the most important step in reclamation is to prevent pollutants from entering the lake to the maximum extent possible and to use a combination of several reclamation methods as a matter of good practice. Stable environmental conditions have developed in the lake, and the values of chlorophyll a and the Secchi disk visibility indicate that the lake has reached a mesotrophic state.
اظهر المزيد [+] اقل [-]Application of Natural Organic Residues as Adsorbents to Remove Lead from Waters
2019
Oliveira, Luciana C. | Botero, Wander G. | Farias, Tamyris S. | Santos, Josué C. C. | Gabriel, Gabriele V. M. | Goveia, Danielle | Cacuro, Thiago A. | Waldman, Walter R.
The contamination of the environment by potentially toxic metals is highlighted by possible impacts of their high availability. Thus, the development of alternative absorbents that can be used in the remediation of contaminated areas, systems that are able to interact with these metals and affect their disposal, transportation, and bioavailability, is of great interest. Natural organic residue (NOR), often discarded as waste, is a promising alternative because it is capable of affecting the bioavailability of potentially toxic metals in the environment. This study assessed the interaction between NOR and NOR ashes (inorganic constituents) and lead ion (Pb²⁺), and its potential of adsorption, in order to analyze their use in contaminated areas. Two different NOR were evaluated and its structural characteristics presented differences in their organic material content and in its complexing capacity. NOR2 presented better capacity of complexing and adsorption of Pb²⁺ ions, performance that must be associated to the higher amount of organic matter present in the soil of this residue. In addition, the adsorption at pH 7.0 occurred through specific interactions with certain functional groups on the surface of NOR and NOR ashes. Besides that, the retention capacity of the Pb²⁺ ions was concentration dependent, in which the highest amount of mass will be the adsorbent retention. In light of this, the results obtained in this work highlight the importance of natural organic residues as a natural adsorbent material to lead removal.
اظهر المزيد [+] اقل [-]Evaluation of conventional drinking water treatment plant efficiency according to water quality index and health risk assessment
2019
Alver, Alper
The objective of this research is to investigate the effluent water quality of a treatment plant in Turkey fed from surface and groundwater, according to water quality index (WOI) and health risk assessment (HRA). In order to achieve this goal, the quality of the influent and effluent water of the treatment plant was monitored monthly from January 2017 to January 2019. Water quality parameter results were compared with the Turkish drinking water standards and the World Health Organization (WHO), revealing that all parameters were within approved limits. Principal component analysis (PCA) was applied to determine the water quality parameter impacts in the overall quality of water and the most attractive parameters were trace elements, heavy metals, NH₃-N, NO₃, and TKN. To evaluate water quality and the impacts on human health, WQI and HRA, including hazard quotient (HQ) and hazard index (HI), were used. The WQI values were calculated by taking into account PCA results. WQI results demonstrated that the influent and effluent of water treatment plant values have a small number of WQI ranking that expressed the water category was “excellent” for drinking purpose. Finally, metal contamination in influent and effluent waters was assessed and the associated health risks to rural populations were estimated for different age groups, children and adults in the service area of the treatment plant. The health risk assessment with similar to WQI results, the acute, sub-chronic, and chronic risks of trace elements was “negligible” level, i.e., to a level affecting 1 person in 1,000,000 inhabitants.
اظهر المزيد [+] اقل [-]Virulence, antimicrobial and heavy metal tolerance, and genetic diversity of Vibrio cholerae recovered from commonly consumed freshwater fish
2019
Xu, Mengjie | Wu, Jinrong | Chen, Lanming
Vibrio cholerae is a leading waterborne pathogen worldwide. Continuous monitoring of V. cholerae contamination in aquatic products and identification of risk factors are crucial for assuring food safety. In this study, we determined the virulence, antimicrobial susceptibility, heavy metal tolerance, and genetic diversity of 400 V. cholerae isolates recovered from commonly consumed freshwater fish (Aristichthys nobilis, Carassius auratus, Ctenopharyngodon idellus, and Parabramis pekinensis) collected in July and August of 2017 in Shanghai, China. V. cholerae has not been previously detected in the half of these fish species. The results revealed an extremely low occurrence of pathogenic V. cholerae carrying the major virulence genes ctxAB (0.0%), tcpA (0.0%), ace (0.0%), and zot (0.0%). However, high incidence of virulence-associated genes was observed, including the RTX toxin gene cluster (rtxA-D) (83.0–97.0%), hlyA (87.8%), hapA (95.0%), and tlh (76.0%). Meanwhile, high percentages of resistance to antimicrobial agents streptomycin (65.3%), ampicillin (44.5%), and rifampicin (24.0%) were observed. Approximately 30.5% of the isolates displayed multidrug resistant (MDR) phenotypes with 42 resistance profiles, which were significantly different among the four fish species (MARI, P = 0.001). Additionally, tolerance of isolates to heavy metals Hg²⁺ (49.3%), Zn²⁺ (30.3%), and Pb²⁺ (12.0%) was observed. The enterobacterial repetitive intergenic consensus-polymerase chain reaction (ERIC-PCR)-based fingerprinting of the 400 V. cholerae isolates revealed 328 ERIC-genotypes, which demonstrated a large degree of genomic variation among the isolates. Overall, the results of this study support the need for food safety risk assessment of aquatic products.
اظهر المزيد [+] اقل [-]Modification of the Relative Abundance of Constituents Dissolved in Drinking Water Caused by Organic Pollution: a Case of the Toluca Valley, Mexico
2019
de Oca, Reyna María Guadalupe Fonseca-Montes | Ramos Leal, Alfredo | Solache-Ríos, Marcos José | Martínez-Miranda, Verónica | Fuentes Rivas, Rosa María
Drinking water contains geogenic elements to which human beings are exposed; in the long term, these elements can be either harmful (As) or beneficial (Mg and Ca) to health. The composition and relative abundance of the constituents in groundwaters are conditioned by the balance between dissolution, precipitation, and oxide-reduction processes also by the nature and spatial arrangement of the materials interacting with the water. In recent decades, human activities and changes in the use of land have led to the accumulation of organic materials and their degradation into nitrogen and phosphorus, which has resulted in a change of the physicochemical composition and quality of drinking water. The main target of the study was to evaluate the effect of contamination by nitrogen and phosphate organic matter on the physicochemical composition of water used for human consumption. The study was conducted in the Toluca Valley aquifer. The determination of parameters in situ and analysis in the laboratory of physicochemical parameters revealed the presence of NO₃⁻ (1.0–119 mg L⁻¹), SO₄²⁻ (6.81–24.70 mg L⁻¹), PO₄³⁻ (2.50–32.20 mg L⁻¹), and N-NH₄⁺ (0–5.40 mg L⁻¹), which suggested the presence of punctual anthropogenic contamination; this was confirmed using 3D fluorescence to identify the presence of organic matter. The results of Na⁺ (15.75 mg L⁻¹), K⁺ (2.66 mg L⁻¹), Ca²⁺ (8.73 mg L⁻¹), and Mg²⁺ (8.01 mg L⁻¹) using the ICP technique showed that the water supplied in the area has a low mineral content. Correlation between P and cations Ca²⁺ (0.844) > Na⁺ (0.720) > Mg²⁺ (0.694) > K⁺ (0.60) indicates that anthropic contamination affects the relative abundance of dissolved constituents in water. The scarcity of essential nutrients in water impacts on public health; it has been reported that deficiency of Ca²⁺ and Mg² implies a wide variety of clinical conditions, mainly in the development of cardiovascular diseases.
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