Mesoscale trajectory modeling for the Brisbane airshed

The main objective of this research is to identify the possible pollutant transport trajectories from the source to the receptor and to identify the location of areas of high pollution potential for ozone. In order to identify the regions which would most probably be affected by ozone and its precursors, a mesoscale trajectory model is developed and forward air‐parcel trajectories originating from Brisbane city are estimated. Eight trajectories per day, starting at 00, 03, 06, 09, 12, 15, 18 and 21 hours, are calculated for one complete calendar year. The probability distribution of trajectories shows seasonal and diurnal characteristics and prevailing transport routes of air pollution. Computer‐driven trajectories indicate that air parcels are concentrated in a region between mountainous ranges in the West and islands in the East. This study identifies potential pollutant transport paths and zones of high concentrations that would assist planners in selecting appropriate areas for future industrial and urban development.     

An overview and analysis of site remediation technologies

This paper presents an analysis of the site restoration techniques that may be employed in a variety of contaminated site cleanup programs. It is recognized that no single specific technology may be considered as a panacea for all contaminated site problems. An easy-to-use summary of the analysis of the important parameters that will help in the selection and implementation of one or more appropriate technologies in a defined set of site and contaminant characteristics is also included.     

Fungicidal impact on chickpea--Mesorhizobium symbiosis

The effects of carbendazim, captan, thiram, and mancozeb, on plant vitality, chlorophyll content, N uptake, protein content, nodulation, and seed yield in chickpea (Cicer arietinun) were assessed in a controlled environment. Seeds treated with fungicides at 1 and 1.5 g.a.i. kg seed had no significant adverse effect on plant vigor, seed yield, and N and protein contents. In contrast, fungicides applied at 2 g.a.i./kg of captan, thiram and mancozeb, significantly reduced the measured parameters. In general, the toxicity of fungicides in terms of seed yield increased in the following order: Control=carbendazim > thiram > captan > mancozeb. Total chlorophyll content in foliage declined consistently with fungicides dose rates and application days. Seeds treated with lower rates of fungicides significantly increased nodulation (nodule number per plant and its dry mass) and were compatible with chickpea inoculum used in this study. Although carbendazim at 2 g.a.i. kg seed had no phytotoxic effect assessed under greenhouse conditions, it significantly reduced the chlorophyll content, nodulation (60d) and N content in shoots.     

Elimination of chloramphenicol, sulphamethoxazole and oxytetracycline in shrimp, Penaeus chinensis following medicated-feed treatment

Muscle residue depletion of chloramphenicol (CAP), sulphamethoxazole (SMZ) and oxytetracycline (OTC) following oral administration was evaluated in shrimp, Penaeus chinensis under field conditions. Three groups of shrimps were cultured in tanks filled with seawater and fed a commercial medicated diet containing 2000 mg kg(-1) CAP, SMZ and OTC, respectively, twice daily for 3 days. Sampling was conducted at different intervals (0, 0.5, 1, 1.5, 2, 3, 4, 8, 10, 12, 16, 24, 36, 48, 72, 96, 120, 144, 168 h) after the cessation of medication. Drug analysis was carried out by HPLC. The elimination half-life (t(1/2)) of CAP was 10.04 h, the elimination half-life (t(1/2)) of SMZ was 5.68 h and that of OTC was 16.12 h. If the EU MRPL value of 0.3 ng/g for CAP and MRL value of 0.1 microg/g for SMZ and OTC quoted for muscle from finfish is extended to shrimp muscle, extrapolation of the data indicates that it would be passed after a 139.7 h (95% CI=132.0-144.4 h), 30.6 h (95% CI=27.2-33.1 h), 90.3 h (95% CI=87.9-92.5 h) withdrawal period for CAP, SMZ and OTC in shrimp muscle, respectively.     

Estimation of radon concentrations in coal mines using a hybrid technique calibration curve

The results of epidemiological studies in various countries show that radon and its progeny cause carcinogenic effects on mine workers. Therefore, it becomes of paramount importance to monitor radon concentrations and consequently determine the radon dose rates in coal mines for the protection of coal miners. A new calibration curve was obtained for radon concentration estimation using hybrid techniques. A calibration curve was generated using 226Ra activity concentration measured by a HPGe detector-based gamma-ray spectrometer versus alpha-track-density rate due to radon and its progeny on CR-39 track detector. Using the slope of the experimentally determined curve in the units of Becqueral per kilogram (Bq kg-1) per unit alpha-track-density per hour (cm-2 h-1), radon concentrations (Bq m-3) were estimated using coal samples from various coal mines in two provinces of Pakistan, Punjab and Balochistan. Consequently, radon dose rates were computed in the simulated environment of the coal mines. Results of these computations may be considered with a caveat that the method developed in this paper provides only a screening method to indicate the radon dose in coal mines. It has been shown that the actual measurements of radon concentrations in the coal mines are in agreement with the estimated radon concentrations using the hybrid-technique calibration curve.     

An optimization procedure for the isocratic high-performance liquid chromatographic separations of environmental pollutants

This paper describes the use of the overlapping resolution mapping procedure to optimize the separation of priority pollutants by isocratic, reversed-phase high-performance liquid chromatography. Three classes of pollutants are considered: polycyclic aromatic hydrocarbons, substituted phenols and phthalate esters. The procedure requires only seven chromatographic runs for each set of pollutants before an optimized mobile phase composition is derived which can satisfactorily resolve all the components in the respective mixtures of pollutants. The main advantage of such a systematic scheme to optimize mobile phase compositions is an improvement in method development times compared to conventional techniques. Another benefit is that expenditures on solvents are reduced.     

Optimization of the gradient HPLC separation of selected phthalates using the overlapping resolution mapping technique

Optimization procedures for the reversed-phase separations of six phthalates using the isoselective multisolvent gradient elution (IMGE) system are described. A systematic experimental design has been employed to gather retention data on the compounds in a mixture. The data were then fitted into a second-order polynomial equation and an overlapping resolution mapping (ORM) technique of data analysis was subsequently used to establish the optimum solvent mixture for the highest resolution of all adjacent peaks in the chromatogram.     

Bioaccumulation of metals in human blood in industrially contaminated area

The consumption of contaminated food crops, meat and milk has significantly increased the concentrations of trace metals in human blood as compared to the control area.     

Emission factor estimation for oil and gas facilities

Fugitive emission rate quantification in an oil and gas facility is an important step of risk management. There are several studies conducted by the United States Environmental Protection Agency (USEPA) and American Petroleum Institute (API) proposing methods of estimating emission rates and factors. Four major approaches of estimating these emissions, in the order of their accuracy, are: average emission factor approach, screening ranges emission factor approach, USEPA correlation equation approach, and unit-specific correlation equation approach. The focus of this study is to optimize the USEPA correlation equations to estimate the emission rate of different units in an oil and gas facility. In the developed methodology, the data available from USEPA (1995) is used to develop new sets of equations. A comparison between USEPA correlation equations and the proposed equations is performed to define the optimum sets of equations. It is observed that for pumps, flanges, open-ended lines, and others, the proposed developed equations provide a better estimation of emission rate, whereas for other sources, USEPA equations supply the better estimate of emission rate.