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.     

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.     

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.     

Microbial and enzymatic degradation of PCBs from e-waste-contaminated sites: a review

Environmental Science and Pollution Research - Electronic waste is termed as e-waste and on recycling it produces environmental pollution. Among these e-waste pollutants, polychlorinated biphenyls...     

Modelling of the effect of size on flocculent dust explosions

The effect of size on the severity of explosions involving flocculent materials has been simulated by means of a model previously developed for spherical particles and here extended to the cylindrical geometry of flock. The model consists of the identification of the regime (internal and external heating, pyrolysis/devolatilization reaction, and volatiles combustion) controlling the explosion by the evaluation of dimensionless numbers (Bi, Da, Th and Pc) and then of the estimation of the deflagration index as a function of flocculent size. The model has been validated by means of explosion data of polyamide 6.6 (nylon) at varying diameter and length. The comparison between model and experimental data show a fairly good agreement.     

A rough set-based game theoretical approach for environmental decision-making: A case of offshore oil and gas operations

Environmental decision-making in offshore oil and gas (OOG) operations can be extremely complex due to conflicting objectives or criteria, availability of vague and uncertain information, and interdependency among multiple decision-makers. Most existing studies ignore conflicting preferences and strategic interactions among decision-makers. This paper presents a game theoretical approach to solve multi-criteria conflict resolution problem under constrained and uncertain environments. Uncertainties in the quantification of imprecise data are expressed using rough numbers. A multi-criteria game is developed to model a decision problem in which three groups of decision-makers (i.e., operators, regulators and service engineers) are involved. This game is solved using the generalized maximin solution concept. With the solution (i.e., optimal weights of the criteria), the rough numbers can be aggregated to an expected payoff for each alternative. Finally, the weights of upper and lower limits of a rough number are employed to transform the expected payoff into a crisp score, based on which all alternatives are ranked to identify the best one. A numerical example is outlined to demonstrate the application of the proposed method to the selection of management scenarios of drilling wastes.     

A spatial econometric analysis of convergence in global environmental performance

Environmental Science and Pollution Research - This study intends to test the presence of β-convergence in the global Environmental Performance (EP). For this purpose, spatial Green Solow...     

Hydrochemical characteristics and identification of groundwater pollution sources in tropical savanna

Groundwater pollution of the watershed is mainly influenced by the multifaceted interactions of natural and anthropogenic processes. In this study, classic chemical and multivariate statistical methods were utilized to assess the groundwater quality and ascertain the potential contamination sources affecting the groundwater quality of Galma sub-watershed in a tropical savanna. For this purpose, the data set of 18 groundwater quality variables covering 57 different sampling boreholes (BH) was used. The groundwater samples essentially contained the cations in the following order of dominance: Ca²⁺ ?>?Na⁺ ?>?Mg²⁺ ?>?K⁺. However, the anions had HCO₃^–?>?Cl^–?>?SO₄^–2?>?NO₃^– respectively. The hydrochemical facies classified the groundwater types of the sub-watershed into mixed Ca–Mg–Cl type of water, which means no cations and anions exceeds 50%. The second dominant water type was Ca–Cl. The Mg–HCO₃ water type was found in BH 9, and Na–Cl water type in BH 29 of the studied area. The weathering of the basement rocks was responsible for the concentrations of these ions in the groundwater chemistry of the sub-watershed. Hierarchical cluster analysis (HCA) grouped the groundwater samples (boreholes) into five clusters that are statistically significant regarding the similarities of groundwater quality characteristics. The principal component analysis (PCA) extracted two major principal components explained around 65% of the variance and suggested the natural and anthropogenic processes especially the agricultural pollutants including synthetic fertilizers, and leaching of agricultural waste as the main factors affecting the groundwater quality. The integrated method proved to be efficient and robust for groundwater quality evaluation, as it guaranteed the precise assessment of groundwater chemistry in the sub-watershed of the tropical savanna. The findings of this investigation could be useful to the policy makers for developing effective groundwater management plans for the groundwater resources and protection of the sub-watershed.

     

Ag nanoparticle-decorated chitosan/SrSnO3 nanocomposite for ultrafast elimination of antibiotic linezolid and methylene blue

Environmental Science and Pollution Research - Effective design of ultrafast new-generation photocatalysts is a challenging task that requires highly dedicated efforts. This research focused on the...