Forecasting Daily Maximum Surface Ozone Concentrations in Brunei Darussalam—An ARIMA Modeling Approach

Abstract

A time series approach using autoregressive integrated moving average (ARIMA) modeling has been used in this study to obtain maximum daily surface ozone (O₃) concentration forecasts. The order of the fitted ARIMA model is found to be (1,0,1) for the surface O₃ data collected at the airport in Brunei Darussalam during the period July 1998-March 1999. The model forecasts of one-day-ahead maximum O₃ concentrations have been found to be reasonably close to the observed concentrations. The model performance has been evaluated on the basis of certain commonly used statistical measures. The overall model performance is found to be quite satisfactory as indicated by the values of Fractional Bias, Normalized Mean Square Error, and Mean Absolute Percentage Error as 0.025, 0.02, and 13.14% respectively.     

Profenofos induced modulation in physiological indices,genomic template stability and protein banding patterns of Anabaena sp. PCC 7120

To understand the mechanism underlying organophosphate pesticide toxicity, cyanobacterium Anabaena PCC 7120 was subjected to varied concentrations (0, 5, 10, 20 and 30 mg L^?1) of profenofos and the effects were investigated in terms of changes in cellular physiology, genomic template stability and protein expression pattern. The supplementation of profenofos reduced the growth, total pigment content and photosynthetic efficiency of the test organism in a dose dependent manner with maximum toxic effect at 30 mg L^?1. The high fluorescence intensity of 2′, 7′ –dichlorofluorescin diacetate and increased production of malondialdehyde confirmed the prevalence of acute oxidative stress condition inside the cells of the cyanobacterium. Rapid amplified polymorphic DNA (RAPD) fingerprinting and SDS-PAGE analyses showed a significant alteration in the banding patterns of DNA and proteins respectively. A marked increase in superoxide dismutase, catalase, peroxidase activity and a concomitant reduction in glutathione content indicated their possible role in supporting the growth of Anabaena 7120 up to 20 mg L^?1. These findings suggest that the uncontrolled use of profenofos in the agricultural fields may not only lead to the destruction of the cyanobacterial population, but it would also disturb the nutrient dynamics and energy flow.     

Phase behaviors,fuel properties,and combustion characteristics of alcohol-vegetable oil-diesel microemulsion fuels

Biofuels are being considered as alternatives to fossil-based fuels due to depletion of petroleum-based reserves and pollutant emission concerns. Vegetable oils and bioalcohols have proven to be viable alternative fuels both with and without engine modification. However, high viscosity and low energy content are long-term operational problems with vegetable oils and bioalcohols, respectively. Therefore, vegetable oil-based microemulsification is being evaluated as a method to reduce the high viscosity of vegetable oils and enhance the miscibility of alcohol and oil phases. Studies have shown that microemulsification with different alcohols lead to varying fuel properties depending on their structure. The overall goal of this study was to formulate microemulsion fuels with single and mixed alcohol systems by determining the effects of water content, alcohol branching structure and carbon chain length on phase behaviors, fuel properties, and emission characteristics. It was found that microemulsion fuels using certain alcohols displayed favorable stability, properties, and emission characteristics. Flames of fuels with linear short-chain-length alcohols had larger near-burner blue regions and lower CO and soot emissions indicating the occurrence of more complete combustion. In addition to alcohol effects, the effect of vegetable oils, surfactants, and additives on emission characteristics were insightful in pursuit of appropriate microemulsion fuels as cleaner burning alternatives to both No.2 diesel and canola biodiesel.     

Removal of sulfadimethoxine in soil mediated by extracellular oxidoreductases

Sulfadimethoxine (SDM) is an antibiotic commonly used in concentrated animal feeding operations and released into the environment via manure application on agricultural lands. Transformation of antibiotics in soil impacts the likelihood of their entry to water bodies, uptake by plants, and thus their effect on terrestrial and aquatic organisms. We conducted experiments to incubate SDM in a sandy loam soil in the presence of humification enzymes commonly found in natural soil, laccase, horseradish peroxidase, and lignin peroxidase. Incubation with the enzymes led to significant reduction in the fraction of SDM extractable from soil, indicating the formation of bound residues. Such transformation was enhanced when the organic matter content in soil is increased or when certain chemical mediators were used along with laccase. The study provided a basis for understanding the environmental fate of sulfonamides and help with the development of remediation methods to mitigate the release of sulfonamides from soil to water.     

Novel degradation pathway of 4-chloro-2-aminophenol via 4-chlorocatechol in Burkholderia sp. RKJ 800

Burkholderia sp. RKJ 800 utilized 4-chloro-2-aminophenol (4C2AP) as the sole carbon and energy source and degraded it with release of chloride and ammonium ions. The metabolic pathway of degradation of 4C2AP was studied and a novel intermediate, 4-chlorocatechol was identified as a major degradation product of 4C2AP using high-performance liquid chromatography and gas chromatography–mass spectrometry. Enzyme activities for 4C2AP-deaminase and 4-chlorocatechol-1,2-dioxygenase were detected in the crude extracts of the 4C2AP-induced cells of strain RKJ 800. The activity of the 4C2AP-deaminase confirmed the formation of 4-chlorocatechol from 4C2AP and the 4-chlorocatechol-1,2-dioxygenase activity suggested the cleavage of 4-chlorocatechol into 3-chloro-cis,cis-muconate. On the basis of the identified metabolites, we have proposed a novel degradation pathway of 4C2AP for Burkholderia sp. RKJ 800. Furthermore, the potential of Burkholderia sp. RKJ 800 to degrade 4C2AP in soil was also investigated using microcosm studies under laboratory conditions. The results of microcosm studies conclude that Burkholderia sp. RKJ 800 was able to degrade 4C2AP in soil and may be used to remediate 4C2AP-contaminated site. This is the first report of (1) the formation of 4-chlorocatechol and 3-chloro-cis,cis-muconate in the degradation pathway of 4C2AP and (2) bioremediation of 4C2AP by any bacterium.     

Water sustainability: reforming water management in new global era of climate change

The National Seminar on Sustainable Water Resource Management in Era of Changing Climate (NSWRM-2014) on 10–11 January 2014 organised by the Institute of Environment and Sustainable Development and Environmental Science and Technology, Banaras Hindu University, witnessed the presence of experts from environmentalists, industrialists and experts on water resources and its management. The deliberations and scientific discussions led to the conclusion that it is not just the resource but the natural capacity to sustain it that requires monitoring, understanding and stewardship. The focus of governance in India needs to move at a faster pace from conventional methods of sector-based water management to more integrated approach for sustainable water resource management. It is more of the people participation that is the future key towards sustainable water resource management in India.     

Cost Effective Production of Poly-β-Hydroxybutyrate by Bacillus subtilis NG05 Using Sugar Industry Waste Water

The present study describes the treatment of sugar industry waste water and its use as a potential low cost substrate for production of bioplastic by Bacillus subtilis NG05. The B. subtilis NG05 grow at the rate of 0.14 g h^?1 L^?1 of production media used and accumulate the 50.1 % of poly β-hydroxybutyrate (PHB). The phase contrast microscopy revealed the presence of PHB granules in B. subtilis NG05 which was further confirmed by Fourier transform infrared spectroscopy and ¹H-nuclear magnetic resonance. The polymer was further analysed by differential scanning calorimetry. PHB production yield was achieved up to 4.991 g L^?1 with Sugar industry waste water as sole nutrient source. Thus the process provided dual benefits of conversion of a waste material into value added product, PHB and waste management.     

Morphological,compositional and ultrastructural changes in the Scrobicularia plana shell in response to environmental mercury – An indelible fingerprint of metal exposure?

The study aimed to assess morphological, structural and compositional alterations in Scrobicularia plana nacre environmentally exposed to mercury in order to seek out the possibility of the assessed alterations as a monitoring tool to handle complexity and interactions of metals in the environment involving a non-invasive methodology. Bivalves were collected from a mercury contaminated site (Laranjo basin – Ria de Aveiro, Portugal) and a reference site in the same aquatic system. The combination of scanning electron microscopy (SEM) with energy-dispersive X-ray spectroscopy (EDS) technique depicted a sheet like morphology of bivalve nacre collected from the reference site. Moreover, EDS plot exhibited the presence of potassium, oxygen, calcium, and carbon elements. Shells collected from the contaminated area depicted lamellar patches like structures with particle like morphology composition. SEM images corresponding to the elemental analysis by EDS plot clearly denoted the presence of mercury. SEM images from the other locations of the contaminated shells depicted large surface area, a broken or ruptured symmetry of organic matrix as well as crack-like gaps. The influence of environmental mercury affecting the surface morphology of S. plana nacre showed dimple like morphology (as proved by transmission electron microscopy, TEM). The possible explanation may be the replacement of calcium elements with other elements or alloys from the nacre composite collected from contaminated region. Therefore, the nacre fingerprint may be useful as innovative knowledge and applicable tool aiming at risk reduction from noxious mercury present in the environment. Overall results suggested the use of shell as an indelible fingerprint of metal exposure.