The main purpose of this work is to analyze the impact of environmental degradation proxied by CO2 emissions per capita along with some other explanatory variables namely energy use, trade, and human capital on economic growth in selected higher CO2 emissions economies namely China, the USA, India, and Japan. For empirical analysis, annual data over the period spanning between 1971 and 2013 are used. After using relevant and suitable tests for checking data properties, the panel fully modified ordinary least squares (FMOLS) method is employed as an analytical technique for parameter estimation. The panel group FMOLS results reveal that almost all variables are statistically significant, whereby test rejects the null hypotheses of non cointegration, demonstrating that all variables play an important role in affecting the economic growth role across countries. Where two regressors namely CO2 emissions and energy use show significantly negative impacts on economic growth, for trade and human capital, they tend to show the significantly positive impact on economic growth. However, for the individual analysis across countries, the panel estimate suggests that CO2 emissions have a significant positive relationship with economic growth for China, Japan, and the USA, while it is found significantly negative in case of India. The empirical findings of the study suggest that appropriate and prudent policies are required in order to control pollution emerging from areas other than liquefied fuel consumption. The ultimate impact of shrinking pollution will help in supporting sustainable economic growth and maturation as well as largely improve society welfare.
This study aimed at determining the presence and characterization of Escherichia coli and Shiga toxin-producing E. coli (STEC) from imported frozen beef meats. Seventy-four (74) frozen imported beef meat samples from two countries, India (42 samples) and Australia (32 samples), were collected and tested for E. coli. These samples were purchased from the frozen meat sections of five different supermarkets in different locations in Selangor, Malaysia, from April 2012 to October 2014. A total of 222 E. coli strains were isolated from the meat samples; 126 strains were isolated from country A (India), and 96 E. coli strains were from country of origin B (Australia), respectively. A total of 70 E. coli strains were identified and characterized. All E. coli strains were isolated into Fluorocult medium and identified using API 20E kit. All selected E. coli strains were characterized for Shiga toxin genes (stx1 and stx2). All biochemically identified E. coli in this study were further subjected to molecular detection through polymerase chain reaction (PCR) amplification and characterization using 16S ribosomal RNA (rRNA) gene of Shiga toxin-producing E. coli. Of the 70 E. coli strains, 11 strains were positive for both Shiga toxin genes (stx1 and stx2) and 11 (11/70) strains were positive for stx1 gene, while 25 (25/70) strains were positive for stx2 gene. The analysis of 16S rRNA gene of all the E. coli isolates in this study was successfully sequenced and analyzed, and based on sequence data obtained, a phylogenetic tree of the 16S rRNA gene was performed using Clustal W programme in MEGA 6.06 software. Phylogenetic tree showed that the E. coli isolates in our study cluster with the strain of E. coli isolated in other countries, which further confirm that the isolates of E. coli in this study are similar to those obtained in other studies. As a result, all the strains obtained in this study proved to be a strain of pathogenic E. coli, which may cause a serious outbreak of food-borne disease. The isolation of pathogenic E. coli strains from the imported meat samples calls for prudent management of imported meats by the relevant authorities.
Given that drugs and their degradation products are likely to occur as concoctions in wastewater, the degradation of a mixture of two nonsteroidal anti-inflammatory drugs (NSAIDs), diclofenac (DCF) and naproxen (NPX), was investigated by solar photolysis and titanium dioxide (TiO2)-mediated solar photocatalysis using an immersion-well photoreactor. An equimolar ratio (1:1) of both NSAIDs in distilled water, drinking water, and river water was subjected to solar degradation. Solar photolysis of the DCF and NPX mixture was competitive particularly in drinking water and river water, as both drugs have the ability to undergo photolysis. However, the addition of TiO2 in the mixture significantly enhanced the degradation rate of both APIs compared to solar photolysis alone. Mineralization, as measured by chemical oxygen demand (COD), was incomplete under all conditions investigated. TiO2-mediated solar photocatalytic degradation of DCF and NPX mixtures produced 15 identifiable degradants corresponding to degradation of the individual NSAIDs, while two degradation products with much higher molecular weight than the parent NSAIDs were identified by liquid chromatography mass spectrometry (LC-MS) and Fourier transform-ion cyclotron resonance-mass spectrometry (FT-ICR-MS). This study showed that the solar light intensity and the water matrix appear to be the main factors influencing the overall performance of the solar photolysis and TiO2-mediated solar photocatalysis for degradation of DCF and NPX mixtures.
Dhaka and its neighboring areas suffer from severe air pollution, especially during dry season (November-April). We investigated temporal and directional variations in particulate matter (PM) concentrations in Dhaka, Gazipur, and Narayanganj from October 2012 to March 2015 to understand different aspects of PM concentrations and possible sources of high pollution in this region. Ninety-six-hour backward trajectories for the whole dry season were also computed to investigate incursion of long-range pollution into this area. We found yearly PM10 concentrations in this area about three times and yearly PM2.5 concentrations about six times greater than the national standards of Bangladesh. Dhaka and its vicinity experienced several air pollution episodes in dry season when PM2.5 concentrations were 8-13 times greater than the World Health Organization (WHO) guideline value. Higher pollution and great contribution of PM2.5 most of the time were associated with the north-westerly wind. Winter (November to January) was found as the most polluted season in this area, when average PM10 concentrations in Dhaka, Gazipur, and Narayanganj were 257.1, 240.3, and 327.4 μg m(-3), respectively. Pollution levels during wet season (May-October) were, although found legitimate as per the national standards of Bangladesh, exceeded WHO guideline value in 50 % of the days of that season. Trans-boundary source identifications using concentration-weighted trajectory method revealed that the sources in the eastern Indian region bordering Bangladesh, in the north-eastern Indian region bordering Nepal and in Nepal and its neighboring areas had high probability of contributing to the PM pollutions at Gazipur station.
A study was carried out to determine the pathogenicity (hemolytic activity) on corals (Turbinaria sp.) and sea bass (Lates calcarifer) of Aeromonas hydrophila from water, sediment, and coral. Samples were collected from coastal water and coral reef areas. One hundred and sixty-two isolates were successfully isolated. Out of 162, 95 were from seawater, 49 from sediment, and 18 from coral. Sixteen isolates were picked and identified. Isolates were identified using a conventional biochemical test, the API 20NE kit, and 16S rRNA nucleotide sequences. Hemolytic activity was determined. Out of 16 isolates, 14 isolates were β-hemolytic and two isolates were non-hemolytic. Corals infected with A. hydrophila suffered bleaching. Similar effect was observed for both hemolytic and non-hemolytic isolates. Intramuscular injection of A. hydrophila into sea bass resulted in muscular bleeding and death. Higher infection rates were obtained from hemolytic compared to non-hemolytic strains of A. hydrophila isolates.
In the present work, the efficiency of the sonication, electrocoagulation, and sono-electrocoagulation process for removal of pollutants from the industrial effluent of the pulp and paper industry was compared. The experimental results showed that the sono-electrocoagulation process yielded higher pollutant removal percentage compared to the sonication and electrocoagulation process alone. The effect of the operating parameters in the sono-electrocoagulation process such as electrolyte concentration (1-5 g/L), current density (1-5 A/dm(2)), effluent pH (3-11), COD concentration (1500-6000 mg/L), inter-electrode distance (1-3 cm), and electrode combination (Fe and Al) on the color removal, COD removal, and power consumption were studied. The maximum color and COD removal percentages of 100 and 95 %, respectively, were obtained at the current density of 4 A/dm(2), electrolyte concentration of 4 g/L, effluent pH of 7, COD concentration of 3000 mg/L, electrode combination of Fe/Fe, inter-electrode distance of 1 cm, and reaction time of 4 h, respectively. The color and COD removal percentages were analyzed by using an UV/Vis spectrophotometer and closed reflux method. The results showed that the sono-electrocoagulation process could be used as an efficient and environmental friendly technique for complete pollutant removal.
This study investigated the effect of different supporting electrolyte (Na2SO4, MgSO4, NaCl) in degradation of Reactive Black 5 (RB5) and generation of electricity. Zinc oxide (ZnO) was immobilized onto carbon felt acted as photoanode, while Pt-coated carbon paper as photocathode was placed in a single chamber photocatalytic fuel cell, which then irradiated by UV lamp for 24 h. The degradation and mineralization of RB5 with 0.1 M NaCl rapidly decreased after 24-h irradiation time, followed by MgSO4, Na2SO4 and without electrolyte. The voltage outputs for Na2SO4, MgSO4 and NaCl were 908, 628 and 523 mV, respectively, after 24-h irradiation time; meanwhile, their short-circuit current density, J SC, was 1.3, 1.2 and 1.05 mA cm(-2), respectively. The power densities for Na2SO4, MgSO4 and NaCl were 0.335, 0.256 and 0.245 mW cm(-2), respectively. On the other hand, for without supporting electrolyte, the voltage output and short-circuit current density was 271.6 mV and 0.055 mA cm(-2), respectively. The supporting electrolyte NaCl showed greater performance in degradation of RB5 and generation of electricity due to the formation of superoxide radical anions which enhance the degradation of dye. The mineralization of RB5 with different supporting electrolyte was measured through spectrum analysis and reduction in COD concentration.
One of the environmental challenges that modern poultry industry faced is odor pollution caused by ammonia emission. The objectives of the study were to determine the effect of sodium butyrate on the production of ammonia in the cecal contents of laying hens using in vitro gas production study and to elucidate the mechanism behind it. The study consisted of a control (without sodium butyrate), and three experimental groups added with 10, 15, and 20 mg of sodium butyrate, respectively. Results showed that ammonia production in headspace of the syringe decreased by 8.2, 23, and 23 %, respectively, while ammonium production from the fermentation broth decreased by 6.3, 14.4, and 13.7 %, respectively. Sodium butyrate had no significant effect on the contents of uric acid and urea, nitrate-N, or total N in all treatments. However, sodium butyrate decreased the urease and uricase activities (P
The Bernam River is one of the most important rivers in Malaysia in that it provides water for industries and agriculture located along its banks. The present study was conducted to assess the level of contamination of heavy metals (Cd, Ni, Cr, Sn, and Fe) in surface sediments in the Bernam River. Nine surface sediment samples were collected from the lower, middle, and upper courses of the river. The results indicated that the concentrations of the metals decreased in the order of Sn > Cr > Ni > Fe > Cd (56.35, 14.90, 5.3, 4.6, and 0.62 μg/g(1) dry weight). Bernam River sediments have moderate to severe enrichment for Sn, moderate for Cd, and no enrichment for Cr, Ni, and Fe. The contamination factor (CF) results demonstrated that Cd and Sn are responsible for the high contamination. The pollution load index (PLI), for all the sampling sites, suggests that the sampling stations were generally unpolluted with the exception of the Bagan Tepi Sungai, Sabak Bernam, and Tanjom Malim stations. Multivariate techniques including Pearson's correlation and hierarchical cluster analysis were used to apportion the various sources of the metals. The results suggested that the sediment samples collected from the upper course of the river had lower metal concentrations, while sediments in the middle and lower courses of the river had higher metal concentrations. Therefore, our results can be useful as a baseline data for government bodies to adopt corrective measure on the issues related to heavy metal pollution in the Bernam River in the future.
The solar flat plate collector operating under different convective modes has low efficiency for energy conversion. The energy absorbed by the working fluid in the collector system and its heat transfer characteristics vary with solar insolation and mass flow rate. The performance of the system is improved by reducing the losses from the collector. Various passive methods have been devised to aid energy absorption by the working fluid. Also, working fluids are modified using nanoparticles to improve the thermal properties of the fluid. In the present work, simulation and experimental studies are undertaken for pipe flow at constant heat flux boundary condition in the mixed convection mode. The working fluid at low Reynolds number in the mixed laminar flow range is undertaken with water in thermosyphon mode for different inclination angles of the tube. Local and average coefficients are determined experimentally and compared with theoretical values for water-based Al2O3 nanofluids. The results show an enhancement in heat transfer in the experimental range with Rayleigh number at higher inclinations of the collector tube for water and nanofluids.
This is the first extensive report on linear alkylbenzenes (LABs) as sewage molecular markers in surface sediments collected from the Perlis, Kedah, Merbok, Prai, and Perak Rivers and Estuaries in the west of Peninsular Malaysia. Sediment samples were extracted, fractionated, and analyzed using gas chromatography mass spectrometry (GC-MS). The concentrations of total LABs ranged from 68 to 154 (Perlis River), 103 to 314 (Kedah River), 242 to 1062 (Merbok River), 1985 to 2910 (Prai River), and 217 to 329 ng g(-1) (Perak River) dry weight (dw). The highest levels of LABs were found at PI3 (Prai Estuary) due to the rapid industrialization and population growth in this region, while the lowest concentrations of LABs were found at PS1 (upstream of Perlis River). The LABs ratio of internal to external isomers (I/E) in this study ranged from 0.56 at KH1 (upstream of Kedah River) to 1.35 at MK3 (Merbok Estuary) indicating that the rivers receive raw sewage and primary treatment effluents in the study area. In general, the results of this paper highlighted the necessity of continuation of water treatment system improvement in Malaysia.
Pristine chitosan beads were modified with sulfur (S)-containing functional groups to produce thiolated chitosan beads (ETB), thereby increasing S donor ligands and crosslinks. The effect of temperature, heating time, carbon disulfide (CS2)/chitosan ratio, and pH on total S content of ETB was examined using Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. The total S content of ETB increased with increasing CS2/chitosan ratio and decreased with decreasing pH and increasing temperature (>60 °C) and heating time (at 60 °C). Spectroscopic analyses revealed the presence of thiol (-SH)/thione, disulfide (-S-S-), and sulfonate groups in ETB. The thiolation mechanism involves decomposition of dithiocarbamate groups, thereby forming thiourea crosslinks and trithiocarbonate, resulting in -SH oxidation to produce -S-S- crosslinks. The partially formed ETB crosslinks contribute to its acid stability and are thermodynamically feasible in adsorbing Cd and Cu. The S-containing functional groups added to chitinous wastes act as sorbents for metal remediation from acidic environments.
Quorum-sensing regulates bacterial biofilm formation and virulence factors, thereby making it an interesting target for attenuating pathogens. In this study, we investigated anti-biofilm and anti-quorum-sensing compounds from secondary metabolites of halophiles marine streptomyces against urinary catheter biofilm forming Proteus mirabilis without effect on growth viability. A total of 40 actinomycetes were isolated from samples collected from different places in Iraq including marine sediments and soil samples. Fifteen isolates identified as streptomyces and their supernatant screened as anti-quorum-sensing by inhibiting quorum-sensing regulated prodigiosin biosynthesis of Serratia marcescens strain Smj-11 as a reporter strain. Isolate Sediment Lake Iraq (sdLi) showed potential anti-quorum-sensing activity. Out of 35 clinical isolates obtained from Urinary catheter used by patient at the Universiti Kebangsaan Malaysia Medical Center, 22 isolates were characterized and identified as Proteus mirabilis. Isolate Urinary Catheter B4 (UCB4) showed the highest biofilm formation with highest resistance to used antibiotic and was chosen for further studies. Ethyl acetate secondary metabolites extract was produced from sdLi isolate. First, we determined the Minimum Inhibitory Concentration (MIC) of sdLi crude extract against UCB4 isolate, and all further experiments used concentrations below the MIC. Tests of subinhibitory concentrations of sdLi crude extract showed good inhibition against UCB4 isolate biofilm formation on urinary catheter and cover glass using Scanning electron microscopy and light microscopy respectively. The influence of sub-MIC of sdLi crude extract was also found to attenuate the quorum sensing (QS)-dependent factors such as hemolysin activity, urease activity, pH value, and motility of UCB4 isolate. Evidence is presented that these nontoxic secondary metabolites may act as antagonists of bacterial quorum sensing by competing with quorum-sensing signals for receptor binding.
Dioxin-like compounds (DLCs) have been classified by the World Health Organization (WHO) as one of the most persistent toxic chemical substances in the environment, and they are associated with several occupational activities and industrial accidents around the world. Since the end of the 1970s, these toxic chemicals have been banned because of their human toxicity potential, long half-life, wide dispersion, and they bioaccumulate in the food web. This review serves as a primer for environmental health professionals to provide guidance on short-term risk assessment of dioxin and to identify key findings for health and exposure assessment based on policies of different agencies. It also presents possible health effects of dioxins, mechanisms of action, toxic equivalency factors (TEFs), and dose-response characterization. Key studies related to toxicity values of dioxin-like compounds and their possible human health risk were identified through PubMed and supplemented with relevant studies characterized by reviewing the reference lists in the review articles and primary literature. Existing data decreases the scope of analyses and models in relevant studies to a manageable size by focusing on the set of important studies related to the perspective of developing toxicity values of DLCs.
This study was carried out to investigate the physicochemical properties of compost from oil palm empty fruit bunches (EFB) inoculated with effective microorganisms (EM∙1™). The duration of microbial-assisted composting was shorter (∼7 days) than control samples (2 months) in a laboratory scale (2 kg) experiment. The temperature profile of EFB compost fluctuated between 26 and 52 °C without the presence of consistent thermophilic phase. The pH of compost changed from weak acidic (pH ∼5) to mild alkaline (pH ∼8) because of the formation of nitrogenous ions such as ammonium (NH4 (+)), nitrite (NO2 (-)), and nitrate (NO3 (-)) from organic substances during mineralization. The pH of the microbial-treated compost was less than 8.5 which is important to prevent the loss of nitrogen as ammonia gas in a strong alkaline condition. Similarly, carbon mineralization could be determined by measuring CO2 emission. The microbial-treated compost could maintain longer period (∼13 days) of high CO2 emission resulted from high microbial activity and reached the threshold value (120 mg CO2-C kg(-1) day(-1)) for compost maturity earlier (7 days). Microbial-treated compost slightly improved the content of minerals such as Mg, K, Ca, and B, as well as key metabolite, 5-aminolevulinic acid for plant growth at the maturity stage of compost. Graphical Abstract Microbial-assisted composting on empty fruit bunches.
This study investigates the relationship between energy consumption and carbon dioxide emission in the causal framework, as the direction of causality remains has a significant policy implication for developed and developing countries. The study employed maximum entropy bootstrap (Meboot) approach to examine the causal nexus between energy consumption and carbon dioxide emission using bivariate as well as multivariate framework for Malaysia, over a period of 1975-2013. This is a unified approach without requiring the use of conventional techniques based on asymptotical theory such as testing for possible unit root and cointegration. In addition, it can be applied in the presence of non-stationary of any type including structural breaks without any type of data transformation to achieve stationary. Thus, it provides more reliable and robust inferences which are insensitive to time span as well as lag length used. The empirical results show that there is a unidirectional causality running from energy consumption to carbon emission both in the bivariate model and multivariate framework, while controlling for broad money supply and population density. The results indicate that Malaysia is an energy-dependent country and hence energy is stimulus to carbon emissions.
This paper examines whether attitudes towards electric vehicles (ATEVs), subjective norms (SNs) and perceived behavioural control (PBC) have significant associations with consumer purchase intention (PI) and the purchase behaviour of environmentally friendly vehicles (EFVs). The results from the survey questionnaires are analysed using confirmatory factor analysis (CFA) and structural equation modelling (SEM). The findings of this paper indicate that ATEV, SN and PBC significantly influence PI. This finding also indicates that environmental consequence and individual preferences do not influence the PI of the respondents. We found that Malaysian car owners are largely unaware of the greenhouse effects on the environment or attach to it little importance, which is reflected in their PI towards EFVs. The outcomes of this study could help policymakers design programmes to influence attitudes, subjective norms, perceived behavioural control and purchase behaviour to prevent further air pollution and reduce CO2 emissions from the transportation sector.
The purpose of this study is to explore the effect of financial development on CO2 emission in 129 countries classified by the income level. A panel CO2 emission model using urbanisation, GDP growth, trade openness, petroleum consumption and financial development variables that are major determinants of CO2 emission was constructed for the 1980-2011 period. The results revealed that the variables are cointegrated based on the Pedroni cointegration test. The dynamic ordinary least squares (OLS) and the Granger causality test results also show that financial development can improve environmental quality in the short run and long run due to its negative effect on CO2 emission. The rest of the determinants, especially petroleum consumption, are determined to be the major source of environmental damage in most of the income group countries. Based on the results obtained, the investigated countries should provide banking loans to projects and investments that can promote energy savings, energy efficiency and renewable energy to help these countries reduce environmental damage in both the short and long run.
Titanium dioxide (TiO2) has been considered a useful material for the treatment of wastewater due to its non-toxic character, chemical stability and excellent electrical and optical properties which contribute in its wide range of applications, particularly in environmental remediation technology. However, the wide band gap of TiO2 photocatalyst (anatase phase, 3.20 eV) limits its photocatalytic activity to the ultraviolet region of light. Besides that, the electron-hole pair recombination has been found to reduce the efficiency of the photocatalyst. To overcome these problems, tailoring of TiO2 surface with rare earth metals to improve its surface, optical and photocatalytic properties has been investigated by many researchers. The surface modifications with rare earth metals proved to enhance the efficiency of TiO2 photocatalyts by way of reducing the band gap by shifting the working wavelength to the visible region and inhibiting the anatase-to-rutile phase transformations. This review paper summarises the attempts on modification of TiO2 using rare earth metals describing their effect on the photocatalytic activities of the modified TiO2 photocatalyst.
The objective of this study is to examine the impact of natural gas consumption, output, and urbanization on CO2 emission in China and India for the period, 1965-2013. A cointegraton test, which provides for endogenously determined structural breaks, has been applied to examine the long-run relationship and to investigate the presence of environmental Kuznets curve (EKC) in the two countries. The presence of causal relationship between the variables is also investigated. The findings show that there is a long-run relationship in the variables and natural gas, real GDP, and urbanization have long-run positive impact on emission in both countries. There is no evidence for EKC in China and India. The findings further suggest that there is a long-run feedback relationship between the variables. The policy inferences of these findings are discussed.