细化搜索
结果 2281-2290 的 4,929
Ecophysiological Responses of a Willow Cultivar (Salix miyabeana ‘SX67’) Irrigated with Treated Wood Leachate
2019
Frédette, Chloé | Comeau, Yves | Brisson, Jacques
As wood preservatives leach from exposed treated wood, they contaminate soil and water, creating an environmental problem that needs to be addressed. Treating this contamination is particularly challenging since it includes mixed compounds, such as heavy metals and trace elements, as well as xenobiotic organic pollutants like polychlorinated dibenzo-dioxin/furan congeners (PCDD/Fs) that are very toxic and are under very strict discharge regulations. Cultivating fast-growing willow shrubs, either in soil or in treatment wetlands, offers a flexible and inexpensive treatment option. The main objective of this study was to evaluate the tolerance of a frequently used willow cultivar (Salix miyabeana ‘SX67’) to irrigation with leachate contaminated with pentachlorophenol (PCP) and chromated chromium arsenate (CCA), two important wood preservatives. We designed a mesocosms experiment with willow grown in three different substrates and irrigated over 12 weeks with three different leachate concentrations. Willow proved to be tolerant to irrigation with the raw leachate, with only leaf area decreasing with increasing leachate concentration. However, the type of growing substrate influenced willow ecophysiological responses and overall performance, and seemed to affect contaminant dynamics in the plant-soil system. All contaminants accumulated in willow roots, and Cu and PCDD/Fs were also translocated to aerial parts. Overall, this study suggests that Salix miyabeana ‘SX67’ could be a good candidate for treating water or soil contaminated with wood preservatives.
显示更多 [+] 显示较少 [-]Study on Mercury Methylation in the Amazonian Rivers in Flooded Areas for Hydroelectric Use
2019
Gomes, Vinicius M. | Santos, Ademir dos | Zara, Luiz F. | Ramos, Dayana D. | Forti, Juliane C. | Ramos, Diovany D. | Santos, Felipe A.
This study aimed to estimate in laboratory the temporal production of methylmercury during the filling of reservoirs of hydropower plants and to correlate it to the ecosystem of different locations in northern Brazil: Jirau hydropower plant in the Madeira River in the state of Rondônia (white waters—under construction), Cana Brava hydropower plant in the Tocantins River in the state of Goiás (clear waters—completed), and the Negro River in the Amazon (black waters—comparative). After collecting water, soil, and sediment samples in the regions mentioned, a microcosm was created to reproduce the conditions close to those found in nature. Water/soil/Hg⁰/Hg²⁺ and water/sediment/Hg⁰/Hg²⁺ were added to glass recipients. Next, methylmercury concentration was monitored by atomic fluorescence spectrometry, total organic carbon by TOC 5000A, and physical and chemical parameters such as pH, redox potential, and dissolved oxygen, for 25 days. The results obtained allow concluding that organic matter plays an important role, providing excess methyl groups to react with inorganic Hg and form organic Hg. The Negro River, which has higher contents of organic matter in its soil, water, and sediment, presented higher potential of mercury methylation in both experiments performed, followed by rivers Madeira and Tocantins.
显示更多 [+] 显示较少 [-]Inequality of female health and its relation with urbanization level in China: geographic variation perspective
2019
Yang, Hao | Pu, Haixia | Wang, Shaobing | Ni, Runxiang | Li, Bin
Urbanization development plays a vital role in the health of modern residents; however, there have been very limited researches to specifically and comprehensively explore the relationship between urbanization level evaluating indicators (ULEIs) and female health outcomes. The mortality rate of breast cancer (BC), cervical cancer (CC), and ovarian cancer (OC) and classified urbanization factor are collected at provincial level. Stepwise regression model (SRM) and geographically weighted regression model (GWRM) are conducted to obtain spatial relationship between the mortality rate of those cancer and ULEI. Our results show that there is remarkable difference of mortality rate of BC, CC, and OC in different provinces as well as higher BC, CC, and OC distributed in northern regions. The increase of value added of primary industry (VAPI), taxi, and coal consumption has detrimental effect on BC and CC. Fuel oil consumption (FOC) ultimately results in increase of mortality rate of BC and OC, and urban fixed asset investment (UFAI) poses a risk to increase the mortality rate of OC. Contrarily, natural gas consumption (NGC) appear to mitigate mortality rate of BC. In particular, our findings demonstrate that there exist spatial differences for VAPI, FOC, NGC, taxi, and coal consumption influencing BC, CC, and OC. It is suggested that policy makers should take account of regional discrepancy and implement a sustainable urbanization development considering female health.
显示更多 [+] 显示较少 [-]Simultaneous removal of nitrate/phosphate with bimetallic nanoparticles of Fe coupled with copper or nickel supported on chelating resin
2019
Shen, Zhanhui | Dong, Xinyi | Shi, Jialu | Ma, Yuanhao | Liu, Daoru | Fan, Jing
Given the prevalence of nitrate and phosphate in surface and groundwater, it is important to develop technology for the simultaneous removal of nitrate and phosphate. In this study, we prepared the bimetallic nanoparticles of Fe coupled with copper or nickel supported on chelating resin DOW 3N (D-Fe/Ni and D-Fe/Cu) for removing nitrate and phosphate simultaneously. XPS profiles revealed that Cu has better ability than Ni to increase the stability of Fe nanoparticles and prevent nZVI from oxidation. The results showed that nitrate removal efficiencies by D-Fe/Ni and D-Fe/Cu were 98.7% and 95.5%, respectively and the phosphate removal efficiencies of D-Fe/Cu and D-Fe/Ni were 99.0% and 93.0%, respectively. Besides adsorption and coprecipitation as reported in previous studies, the mechanism of phosphate removal also includes the adsorption of the newly formed polymeric ligand exchanger (PLE). Moreover, in previous studies, the presence of phosphate had significant negative effects on the reduction of nitrate. However, in this study, the removal efficiency of nitrate was less affected with the increasing concentration of phosphate for D-Fe/Cu. This was mainly because D-Fe/Cu had higher adsorption capacity of phosphate due to the newly formed PLE according to the XPS depth profile analysis.
显示更多 [+] 显示较少 [-]Understanding corporate surplus food donation in China: testing the roles of environmental concern, altruism, past experience, and perceived risk
2019
Liao, Chuanhui | Hong, Jin | Zhao, Dingtao
This paper investigates the motives behind corporate giving and determines whether perceived risk plays a major role in corporate surplus food donation intention. A conceptual model is developed from the perspectives of perceived risk, economic concern, past behavior, and moral motives. A questionnaire survey is conducted among food manufacturers and retailers in the Sichuan Province in China. A total of 143 valid observations are used to conduct structural equation modeling analysis. The results show that corporate reputation, legislation, and business risks are the main sub dimensions of risks that corporations perceive. Perceived risk, past behavior, environmental concern, and altruism affect corporate donation intention significantly. Implications of the findings for promoting surplus food donation are also discussed.
显示更多 [+] 显示较少 [-]Methods for monitoring construction off-road vehicle emissions: a critical review for identifying deficiencies and directions
2019
Sepasgozar, Samad M. E. | Li, Heng | Shirowzhan, Sara | Tam, Vivian W. Y.
The paper reviews the existing applications of sensing technologies for measuring construction off-road vehicle emissions (COVE) such as earthmoving equipment. The current literature presented different measurement methods and reported the results of utilisation of new technologies for measuring COVE. However, previous papers used different technology applications covering only a part of the monitoring process with its own limitations. Since technologies are advancing and offering novel solutions, there is an urgent need to identify the gaps, re-evaluate the current methods, and develop a critical agenda for automating the entire process of collecting emissions data from construction sites, and monitoring the emission contributors across cities. This paper systematically identifies relevant papers through a search of three key databases—Web of Science, Engineering Valley and Scopus—covering the publications in the last decade from 2008 to 2017. An innovative robust research method was designed to select and analyse the relevant papers. The identified papers were stored in a data set, and a thematic algorithm employed to find the clusters of papers which might be potentially relevant. The selected papers were used for further micro-thematic analysis to find key relevant papers on COVE, and the gap in the literature. A sample of relevant papers was found relevant to COVE and critically reviewed by coding and content analysis. This paper critically reviews the selected papers and also shows that there is a considerable gap in the applications of new technologies for measuring in-use COVE in real time based on real activities toward automated methods. This review enables practitioners and scholars to gain a concrete understanding of the gap in measuring COVE and to provide a significant agenda for future technology applications.
显示更多 [+] 显示较少 [-]The characterization and methane adsorption of Ag-, Cu-, Fe-, and H-exchanged chabazite-rich tuff from Turkey
2019
Sakızcı, Meryem | Özer, Mehmet
In this study, a chabazite-rich tuff (CHA) from the Bala deposit of Ankara region (Turkey) and its modified forms (CuCHA, AgCHA, FeCHA, and HCHA samples) were investigated at 273 and 298 K using volumetric apparatus up to 100 kPa. The chabazite samples were characterized by using thermal analysis (TG-DTG-DTA), X-ray diffraction (XRD), X-ray fluorescence (XRF), scanning electron microscopy with detector X-ray energy dispersive (SEM-EDX), Fourier transform infrared (FT-IR), and N₂ adsorption methods. It was found that natural chabazite is composed of predominantly chabazite with small amounts of clinoptilolite and erionite. XRD showed that there are major structural changes to Fe- and H-exchanged chabazite samples. Capacity of chabazites for CH₄ ranged from 0.168 and 1.341 mmol/g. Among all the modified forms, it was observed that Ag form of chabazite zeolite had the greatest methane adsorption capacity at both temperatures.
显示更多 [+] 显示较少 [-]Optimisation of bioscrubber systems to simultaneously remove methane and purify wastewater from intensive pig farms
2019
Liu, Fang | Fiencke, Claudia | Guo, Jianbin | Lyu, Tao | Dong, Renjie | Pfeiffer, Eva-Maria
The use of bioscrubber is attracting increasing attention for exhaust gas treatment in intensive pig farming. However, the challenge is to improve the methane (CH₄) removal efficiency as well as the possibility of pig house wastewater treatment. Three laboratory-scale bioscrubbers, each equipped with different recirculation water types, livestock wastewater (10-times-diluted pig house wastewater supernatant), a methanotroph growth medium (10-times-diluted), and tap water, were established to evaluate the performance of CH₄ removal and wastewater treatment. The results showed that enhanced CH₄ removal efficiency (25%) can be rapidly achieved with improved methanotrophic activity due to extra nutrient support from the wastewater. The majority of the CH₄ was removed in the middle to end part of the bioscrubbers, which indicated that CH₄ removal could be potentially optimised by extending the length of the reactor. Moreover, 52–86% of the ammonium (NH₄⁺-N), total organic carbon (TOC), and phosphate (PO₄³⁻-P) removal were simultaneously achieved with CH₄ removal in the present study. Based on these results, this study introduces a low-cost and simple-to-operate method to improve CH₄ removal and simultaneously treat pig farm wastewater in bioscrubbers.
显示更多 [+] 显示较少 [-]Perception of household in regards to water pollution: an empirical evidence from Pakistan
2019
Ahmed, Adeel | Shafique, Imran
Water pollution is one of the main threats to public health in Pakistan. The watchdogs for drinking water quality are toothless, hence Pakistan’s ranking in maintaining water quality standards is 80th out of 122 nations. Despite such alarming situation coupled with violation of various drinking water quality parameters set by WHO, the risk perception of people remains an unfolded area of research. This paper examines the risk perception of household regarding water pollution in Pakistan and its potential effect on human health. In this way, we present a more analytical interpretation of the subject by collecting data from a survey questionnaire from one of the largest urban cities of Pakistan. Conclusions are drawn which stress that education, income, and knowledge of water pollution have higher impact on risk perception. From this position, and with the development of implications for policy, we demonstrate the need of a systematic quantification of various uncertainties that can provide more realistic support for remediation-related decisions to policy makers.
显示更多 [+] 显示较少 [-]Direct and indirect photolysis of the antibiotic enoxacin: kinetics of oxidation by reactive photo-induced species and simulations
2019
Lastre-Acosta, Arlen Mabel | Barberato, Bruna | Parizi, Marcela Prado Silva | Teixeira, Antonio Carlos Silva Costa
The purpose of this study was to investigate the aqueous phase photochemical behavior of enoxacin (ENO), an antibiotic selected as a model pollutant of emerging concern. The second-order reaction rate constants of ENO with hydroxyl radicals (HO●) and singlet oxygen (¹O₂) were determined at pH 3, 7, and 9. Also, the rate constants of the electron transfer reaction between ENO and triplet states of chromophoric dissolved organic matter (³CDOM*) are reported for the first time, based on anthraquinone-2-sulfonate (AQ2S) as CDOM proxy. The sunlight-driven direct and indirect ENO degradation in the presence of dissolved organic matter (DOM) is also discussed. The results show that direct photolysis, which occurs more rapidly at higher pH, along with the reactions with HO● and ³AQ2S*, is the key pathway involved in ENO degradation. The ENO zwitterions, prevailing at pH 7, show kENO, HO●, kENO,₁O₂, and kENO,₃AQ₂S* of (14.0 ± 0.8) × 10¹⁰, (3.9 ± 0.2) × 10⁶, and (61.5 ± 0.7) × 10⁸ L mol⁻¹ s⁻¹, respectively, whose differences at pH 3, 7, and 9 are due to ENO pH-dependent speciation and reactivity. These k values, along with the experimental ENO photolysis quantum yield, were used in mathematical simulations for predicting ENO persistence in sunlit natural waters. According to the simulations, dissolved organic matter and water depth are expected to have the highest impacts on ENO half-life, varying from a few hours to days in summertime, depending on the concentrations of relevant waterborne species (organic matter, NO₃⁻, NO₂⁻, HCO₃⁻).
显示更多 [+] 显示较少 [-]