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The nexus between urbanization, road infrastructure, and transport energy demand: empirical evidence from Pakistan
2019
Wang, Zhaohua | Ahmed, Zahoor | Zhang, Bin | Wang, Bo
Transport sector of Pakistan contributes more than one half to the national energy consumption. This sector is dominated by road transportation and mainly relies on fossil fuels. The country is going through rapid unplanned urbanization, which can lead to detrimental health and ecological consequences by intensifying road transport energy consumption. Therefore, the current study investigates the effect of urbanization on road sector energy consumption controlling for economic growth, road infrastructure, and industrialization. The autoregressive distributed lag (ARDL) approach is used to examine the long-run and short-run relationship between variables over the period 1971 to 2018. The vector error correction model (VECM) is employed to analyze the causality between variables. The results disclose a significant positive contribution of urbanization to road sector energy consumption. Further, road infrastructure, economic growth, and industrialization stimulate road transport energy consumption. Feedback effect exists between urbanization and road transport energy consumption, while economic growth Granger causes road sector energy consumption, urbanization, and road infrastructure. The findings imply that energy conservation and sustainable urbanization policies are a better choice under the current economic situation. Also, road infrastructure development in rural areas may reduce rural to urban migration.
Show more [+] Less [-]Study on shear behavior of kaolinite contaminated by heavy metal Cu (II)
2019
Zhang, Zhihong | Chen, Yang | Fang, Jianghua | Guo, Fei
Numerous studies have shown that the invasion of the chemicals plays an important role on the geomechanical properties of the soil. This article aims to investigate the shear behavior of contaminated soil by laboratory tests and develop an extended shear strength model on the basis of the experimental results. In order to explicitly evaluate the effect of solution concentration on the shear strength behavior of soil, the remolded samples of kaolinite mixed with different concentrations of CuCl₂ solutions were prepared to carry out a series of consolidated-undrained triaxial shear strength tests. The results indicate that different CuCl₂ solution concentrations have significant influence on the shear strength property of kaolinite. With the increase of CuCl₂ solution concentration, the shear strength of soil displays a declining tendency, and the strength properties including cohesion and internal friction angle are also reduced, which indicates the Cu (II) that existed in the soil samples has deteriorated the soil strength strongly. Based on the experimental results, an extended Mohr–Coulomb strength model for contaminated soils has been proposed by introducing osmotic suction as a macro variable parameter. The conclusions in this study can provide reference for pollution prevention of existing and future foundations.
Show more [+] Less [-]Carbon footprint accounts of Pakistan: an input-output life cycle assessment model
2019
Zeshan, Muhammad
The Paris agreement (2015) seems a significant achievement towards a global mitigation policy to climate change. However, implementing the promised Intended Nationally Determined Contribution (INDC) targets by the participating countries has become a real challenge. In this aspect, the input-output life cycle assessment (IO-LCA) model provides an important assessment mechanism to design suitable abatement policies limiting the rising greenhouse gas (GHG) emissions. The present paper develops an IO-LCA model for Pakistan and estimates all the direct and indirect GHG emissions caused by all the production activities during all the stages of production. This task is achieved in three phases. In phase 1, the Pakistan input-output table (IOT) is constructed. In phase 2, the GHG environmental satellite accounts are created for each sector in the economy. In phase 3, the GHG emissions are linked to different categories of final demand.
Show more [+] Less [-]Fishing lines and fish hooks as neglected marine litter: first data on chemical composition, densities, and biological entrapment from a Mediterranean beach
2019
Battisti, Corrado | Kroha, Silvio | Kozhuharova, Elina | De Michelis, Silvia | Fanelli, Giuliano | Poeta, Gianluca | Pietrelli, Loris | Cerfolli, Fulvio
We reported first data on the densities and chemical composition of fishing lines and fish hooks deposited on a Mediterranean beach. On a sampling area of 1.5 ha, we removed a total of 185,028 cm of fishing lines (density 12.34 cm/m²) and 33 hooks (density 22 units/ha). Totally, 637.62 g (42.5 mg/m²) of fishing lines were collected. We sampled 120 items entangled belongings to 7 animal taxa (density 6.49 items/100 m of fishing lines). We also observed a not quantifiable number of egagropiles (Posidonia oceanica spheroids), Rhodophyceae (Halymenia sp.) and segments of reeds of Phragmites communis, trapped in the fishing lines. Fourier transform infrared (FTIR) spectroscopy was used in order to identify the chemical composition of the fishing lines: 92% was made of nylon while 8.0% was determined as fluorocarbon based polymers (polyvinylidene fluoride). Because of their subtlety and reduced size, sandy beach cleaning operations should include at least two consecutive removal samplings: indeed, a part of this litter (12.14%) is not removed in the first sampling. The unexpected high density of fishing lines suggests specific management actions aimed to periodically remove this neglected anthropogenic litter.
Show more [+] Less [-]Investigating membrane fouling associated with GAC fluidization on membrane with effluent from anaerobic fluidized bed bioreactor in domestic wastewater treatment
2019
Aslam, Muhammad | Kim, Jeonghwan
Effect of mechanical scouring driven by granular activated carbon (GAC) fluidization on membrane fouling was investigated using a laboratory-scaled, fluidized membrane reactor filtering the effluent from anaerobic fluidized bed bioreactor (AFBR) in domestic wastewater treatment. The GAC particles were fluidized by recirculating a bulk solution only through the membrane reactor to control membrane fouling. The membrane fouling was compared with two different feed solutions, effluent taken from a pilot-scaled, AFBR treating domestic wastewater and its filtrate through 0.1-μm membrane pore size. The GAC fluidization driven by bulk recirculation through the membrane reactor was very effective to reduce membrane fouling. Membrane scouring under GAC fluidization decreased reversible fouling resistance effectively. Fouling mitigation was more pronounced with bigger GAC particles than smaller ones as fluidized media. Regardless of the fluidized GAC sizes, however, there was limited effect on controlling irreversible fouling caused by colloidal materials which is smaller than 0.1 μm. In addition, the deposit of GAC particles that ranged from 180 to 500 μm in size on membrane surface was very significant and accelerated fouling rate. Biopolymers rejected by the membranes were thought to play a role as binding these small GAC particles on membrane surface strongly.
Show more [+] Less [-]Virulence profiles of vancomycin-resistant enterococci isolated from surface and ground water utilized by humans in the North West Province, South Africa: a public health perspective
2019
Matlou, Daniel Pheeha | Bissong, Marie Ebob AgborTabot | Tchatchouang, Christ-Donald Kaptchouang | Adem, Mohomud Rashid | Foka, Frank Eric Tatsing | Kumar, Ajay | Ateba, Collins Njie
Vancomycin-resistant enterococci (VRE) have been responsible for numerous outbreaks of serious infections in humans worldwide. Enterococcus faecium and Enterococcus faecalis are the principal species that are frequently associated with vancomycin resistance determinants, thus usually implicated in hospital- and community-acquired infections in humans. The study aim was to determine the antibiotic resistance and virulence profiles of VREs isolated from surface and groundwater samples that are used by humans in the North West Province, South Africa. A total of 170 water samples were collected and analyzed. Eighty-one potential isolates were screened for characteristics of Enterococcus species using preliminary biochemical tests, PCR assays and sequence analysis. The antimicrobial resistance profiles of the isolates against nine antibiotics were determined and a dendrogram was generated to access the relatedness of the isolates. The isolates were screened for the presence of antibiotic resistance and virulence genes by multiplex PCR analysis. A total of 56 isolates were confirmed as Enterococcus species and the proportion of E. faecium (46.9%) was higher than E. faecalis (29%) and E. saccharolyticus (1.2%). Sequence data of E. faecium, E. faecalis, and E. saccharolyticus isolates revealed 97 to 98% similarities to clinical strains deposited in NCBI Genbank. Large proportions (44; 78.6%) of the isolates were resistant to vancomycin while 16 and 3.6% of the isolates possessed the vanA and vanB genes respectively. The MAR phenotype Vancomycin-Nalidixic Acid-Streptomycin-Chloramphenicol-Ampicillin-Oxytetracycline-Gentamycin-Nitrofurantoin-Sulphamethoxazole indicated that some isolates were resistant to all of the nine antibiotics tested. Cluster analysis of antibiotic resistance data revealed two major clusters. Sixteen (36.4%), 14 (27.3%), 3 (6.8%), and 2 (4.5%) of the VRE isolates possessed the gel, asa1, hyl, and esp virulence genes respectively while the cylA gene was not detected in the study. Multiple antibiotic-resistant enterococci were also resistant to vancomycin and possessed virulence determinants indicating that they can pose severe public health complications on individuals who consume contaminated water.
Show more [+] Less [-]Guarana improves behavior and inflammatory alterations triggered by methylmercury exposure: an in vivo fruit fly and in vitro neural cells study
2019
Algarve, Thaís Doeler | Assmann, Charles Elias | Cadoná, Francine Carla | Machado, Alencar Kolinski | Manica-Cattani, Maria Fernanda | Sato-Miyata, Yukiko | Asano, Tsunaki | Duarte, Marta Maria Medeiros Frescura | Ribeiro, Euler Esteves | Aigaki, Toshiro | da Cruz, Ivana Beatrice Mânica
Methylmercury (MeHg) is a well-known environmental pollutant associated with neurological and developmental deficits in animals and humans. However, epidemiological data showed that people living in the Amazon region although exposed to MeHg do not present these effects probably due to the protective effect of certain foods. We hypothesized here if guarana, a highly caffeinated fruit and consumed on a daily basis by Amazon people, could have some protective effect against MeHg toxicity using two complementary approaches. To assess locomotor impairment and sleep disruption, we used fruit fly (Drosophila melanogaster) model, and to evaluate neuroinflammation, we used human SH-SY5Y neural cells by measuring inflammatory cytokines levels. Results showed that guarana had a protective effect on the locomotor activity of male fruit flies reducing the excessive sleepiness caused by MeHg and increasing daily activity. Also, guarana increased the viability of flies and attenuated neural cells mortality. In addition, guarana reduced all pro-inflammatory cytokines levels increased by MeHg, along with caspase-1, caspase -3, caspase-8, and 8-dOHG levels, whereas increased the anti-inflammatory (IL-10) cytokine levels, which was decreased by MeHg. Our study provides new insights on the protective effects of guarana on the viability, locomotor activity, sleep, and activity patterns in vivo and the in vitro neuronal anti-inflammatory effect against MeHg toxicity.
Show more [+] Less [-]Carbon emission intensity of electricity generation in Belt and Road Initiative countries: a benchmarking analysis
2019
Zhang, Xingping | Zhang, Haonan | Zhao, Changhong | Yuan, Jiahai
The scope of this study is to analyze the carbon emissions intensity of electricity generation in “Belt and Road Initiative” (BRI) countries. The total CO₂ emissions from electricity generation in BRI nations increases from 4232.34 Mt in 2013 to 4402.38 Mt in 2015, accounting for 34.45% of global CO₂ emissions from electricity generation. Logarithmic mean Divisia index methodology is applied to analyze the drivers of carbon emissions intensity in BRI nations. The decomposition results revealed that the regional carbon emissions intensity in BRI nations increases during 2013–2015 and the power generation efficiency is the essential factor to improve carbon emissions performance in BRI developing countries. For BRI developing countries, promoting clean and efficient thermal power is a pragmatic priority for green power development.
Show more [+] Less [-]Analysis of methanogens adsorption and biogas production characteristics from different coal surfaces
2019
Guo, Hongyu | Dong, Zhiwei | Liu, Xile | Bai, Yang | Gao, Zhixiang | Xia, Daping
The aim of this study was to examine the biogas production and the adsorption aspect of microorganism from different coals. Coal samples were obtained from Qianqiu mine and Guandi mine. Microbial populations were cultured from the coal mine drainage. After an anaerobic reaction period at about 35 °C, adsorption rate was determined by the spectrophotometer, while a scanning electron microscopy was used to observe the microorganisms on the coal and the headspace methane was analyzed using gas chromatography. Results show that the coal rank and particle size serve as important factors influencing the adsorption of microorganism and biogenic methane production. With decreasing particle size, the Qianqiu coal produced a considerable adsorption rate between 75 and 79%, while the adsorption rate of Guandi coal was between 52 and 74%. Meanwhile, the density of microorganisms from the Qianqiu coal surface demonstrated a higher level of adsorption than that of Guandi coal following the scanning electron microscopy images. Additionally, Qianqiu coal produced a higher level of biogas production (391.766–629.199 μmol/g) than that of Guandi coal (292.835–393.744 μmol/g) and the Qianqiu coal also generated a higher concentration of methane during the incubation. When the adsorption rate decreasing, the biogas production from various pulverized coals appeared to be decreased and demonstrated a positive correlation to the adsorption rate. The results of this study suggest that the adsorption behavior of microorganisms is closely related to the effect of coal biodegradation and contributes to the biogenic methane production potential.
Show more [+] Less [-]Factors influencing mercury uptake by leaves of stone pine (Pinus pinea L.) in Almadén (Central Spain)
2019
Barquero, José Ignacio | Rojas, Sofía | Esbrí, José María | García-Noguero, Eva M. | Higueras, Pablo
The use of trees for biomonitoring of mercury (Hg) and other atmospheric pollutants is of increasing importance today. Leaves from different species have been the most widely used plant organ for this purpose, but only pine bark, and not leaves, was used to monitor Hg pollution. In Almadén (South Central Spain), the largest cinnabar (HgS) deposits in the world have been mined for over 2000 years to obtain metallic Hg and this activity has caused the widespread dispersion of this toxic element in the local environment. A strip of pine trees, 2750 m in length, adjacent and to the South of the mining town has been studied in order to evaluate pine tree needles as monitors for Hg contamination in this heavily polluted area. The study involved the collection of pine tree leaves from several discrete sites along the strip, as well as samples from other nearby locations, together with soil samples and monitoring of atmospheric Hg in the area during both the day and night. Leaves and soils were analyzed for total Hg concentration by means of atomic absorption spectrometry; the leachable fraction of soil Hg was also analyzed by the CV-AFS technique. The results indicate that soils from the investigated area were not directly affected by mining related pollution, with low total Hg levels (3–280 mg kg⁻¹) found in comparison with the nearby Almadén metallurgical precinct and very low leachable Hg contents (0.27–59.65 mg kg⁻¹) were found. Moreover, pine tree needles have a low uptake capacity, with lower THg levels (0.03–6.68 mg kg⁻¹) when compared to those of olive trees in Almadén. However, pine needles do show significant variability with regard to the distance from the source. Gaseous Hg exhibits a similar pattern, with higher levels close to the source, especially during night time (225 ng m⁻³). A multiple linear regression analysis (MLRA) revealed that gaseous Hg in the nocturnal period is the prime factor that influences the amount of Hg uptake by pine tree needles. This finding makes pine needles a promising candidate to biomonitor gaseous Hg on a local or regional scale worldwide. Almadén pine tree needles have been exposed to a number of different Hg sources, including the primary one, namely the old mine dump, and secondary sources such as polluted roads or illegal urban residual waste. The secondary sources cause some minor discrepancies in the model established by the MRLA. The biomonitoring capacity of pine needles needs to be evaluated in areas far from the source. The process involved in gaseous Hg uptake by pine needles appears more likely to involve sorption in the external part of the needle than uptake through stomas, thus making this process strongly dependent on high atmospheric Hg concentrations.
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