Radionuclides (lead-210, polonium-210, thorium-230, and -232) and thorium and uranium in water, sediments, and fish from lakes near the city of Elliot Lake, Ontario, Canada

Radionuclides (210Pb, 210Po, 230Th, and 232Th) and chemical Th and U were measured in water, sediments, and fish tissues (bone, muscle, and gut contents of laketrout, Salvelinus namaycush, whitefish, Coregonus clupeaformis and Prosopium cylindraceum) from four lakes in a watershed affected by U mining and milling operations at Elliot Lake, Ontario, and from control lakes in an adjacent, non-industrialized, watershed. Radionuclide concentration ratios between tissue levels and sediment and water levels were calculated. Annual radionuclide intakes and resulting doses were estimated for humans consuming fish from the watershed. Bone 210Pb levels were higher (186 mBq g(-1) dry wt in laketrout and 230 mBq g(-1) dry wt in one lake whitefish) than in muscle (< 50 mBq g(-1) dry wt in all cases), and generally higher in fish from study lakes than from controls, but no consistent differences were observed among fish species. Similarly, 210Po levels were higher in bone (208 +/- 33 mBq g(-1), in laketrout) than muscle (maximum 26 +/- 4 mBq g(-1), in laketrout), and in study lake populations compared to controls. Laketrout 210Po bone concentrations were higher than previously reported in Canada. Levels of 230Th, 232Th, and Th were below detection limits (20 mBq g(-1), 0.05 microg g(-1)) in body tissues in all fish species. Bone levels of U (14.6 +/- 3.0 microg g(-1), in lake whitefish) were higher than in muscle (most < 0.05 microg g(-1), except 0.12 +/- 0.04 and 0.08 +/- 0.03 microg g(-1) in lake whitefish) in fish from waters affected by industrial activity. In control lakes, bone and muscle levels were lower and not significantly different from each other. Muscle levels did not vary consistently with location. Concentration of 210Pb and U was seen from water and 'gut' material (taken as a surrogate for diet) to bone in laketrout and whitefish, and of U from water to muscle in whitefish, but in no case from sediments to tissues. Human intakes of 210Pb, 210Po, 230Th, 232Th, and U from consuming one meal of fish (375 g) per week could, in aggregate, represent an annual effective dose < 15% of the public dose limit (5 mSv). Monitoring biota living near the decommissioned Elliot Lake U operations, especially of 210Pb levels in fish muscle, with further assessment of human doses attributable to local fish and other animals in the diet, should continue. Because radionuclide effects on fish health (and on other non-human organisms) are of increasing concern, neoplasms, malformations, and reproductive anomalies in local fish deserve examination.     

Pathways and kinetics of carbon tetrachloride and chloroform reductions by nano-scale Fe and Fe/Ni particles: comparison with commercial micro-scale Fe and Zn

Groundwater and wastewater contaminated with chlorinated organic compounds (COCs) can be treated with zero-valent metals. The practicality of this treatment method depends on the reduction rates of the target compounds and their byproducts. In this study, nano-scale Fe and Fe/Ni particles were synthesized so that they could be used to rapidly degrade carbon tetrachloride (CT) and chloroform (CF). Their BET surface areas were around two orders higher than those of commercial micro-scale Fe and Zn particles. Batch reduction experiments carried out with a metal loading of 2.5 gl(-1) showed that complete reduction of CT by the nano-scale Fe/Ni and Fe particles could be achieved within 20 min and 60 min, respectively. With the commercial micro-scale Fe and Zn particles applied at 125 gl(-1), complete CT reduction could only be achieved after 4h and 1.5h, respectively. Reductions of CT and CF with the nano-scale particles followed pseudo-first-order kinetics, and the specific reaction rate constants with the nano-scale Fe/Ni particles were 2-8 times higher than those of the nano-scale Fe particles. CT was degraded through hydrogenolysis to CF, and subsequently via both complete reduction pathway to methane and hydrogenolysis pathway to dichloromethane (DCM). Significantly more methane was generated with the use of the nano-scale Fe/Ni particles than with the nano-scale Fe particles. While the commercial Zn particles were more reactive than the commercial Fe particles, they failed to transform CT directly into methane, causing accumulation of DCM in the aqueous phase.     

Degradation of trichloroethylene by photocatalysis in an internally circulating slurry bubble column reactor

The effects of initial trichloroethylene (TCE) concentration, recirculating liquid flow rate and gas velocity on photodegradation of TCE have been determined in an internally circulating slurry bubble column reactor (0.15m-ID x 0.85 m-high). Titanium dioxide (TiO2) powder was employed as a photocatalyst and the optimum loading of TiO2 in the present system is found to be approximately 0.2 wt%. The stripping fraction of TCE by air flow increases but photodegradation fraction of TCE decreases with increasing the initial TCE concentration, recirculating liquid flow rate and gas velocity. The average removal efficiency of TCE is found to be approximately 97% in an internally circulating slurry bubble column reactor.     

Trichloroethylene degradation by photocatalysis in annular flow and annulus fluidized bed photoreactors

The effects of trichloroethylene (TCE) gas flow rate, relative humidity, TiO(2) film thickness, and UV light intensity on photodegradation of TCE have been determined in an annular flow type photoreactor. Phosgene and dichloroacetyl chloride formation could be controlled as a function of TCE gas flow rate and photodegradation of TCE decreased with increasing relative humidity. The optimum thickness of TiO(2) film was found to be approximately 5 mum and the photocatalytic reaction rate of TCE increased with square root of UV light intensity. In addition, the effects of the initial TCE concentration, phase holdup ratio of gas and solid phases (epsilon(g)/epsilon(s)), CuO loading on the photodegradation of TCE have been determined in an annulus fluidized bed photoreactor. The TCE photodegradation decreased with increasing the initial TCE concentration. The optimum conditions of the phase holdup ratio (epsilon(g)/epsilon(s)) and CuO wt.% for the maximum photodegradation of TCE was found to be 2.1 and 1.1 wt.%, respectively. Therefore, an annulus fluidized bed photoreactor is an effective tool for TCE degradation over TiO(2)/silica gel with efficient utilization of photon energy.     

Anaerobic biotransformation of dinitrotoluene isomers by Lactococcus lactis subsp. lactis strain 27 isolated from earthworm intestine

Dinitrotoluenes are widely used as solvents and are intermediates in the synthesis of dyes, explosives, and pesticides. Environmental concerns regarding DNTs have increased due to their widespread use and their discharge into the environment. In this study, the anaerobic biodegradation of four dinitrotoluene isomers, 2,3-, 2,4-, 2,6- and 3,4-DNT, was investigated using Lactococcus lactis subsp. lactis strain 27, which was isolated from the intestines of earthworms. Liquid chromatography/mass spectrometry and NMR spectroscopy showed that L. lactis strain 27 non-specifically reduced the nitro groups on the tested dinitrotoluenes to their corresponding aminonitrotoluenes. L. lactis strain 27, however, did not reduce either sequentially or simultaneously two nitro groups of the dinitrotoluenes, resulting in the formation of the corresponding diaminotoluenes. In vitro formation of dinitroazoxytoluenes suggested the presence of oxygen-sensitive hydroxylaminonitrotoluenes. L. lactis strain 27 was capable of reducing 2,4-, 2,6-, 2,3-, and 3,4-dinitrotoluenes up to 173.6, 66.6, 287.1, and 355 microM, respectively in 12 h incubation. A relatively rapid reduction was observed in the case of the 2,3-, and 3,4-dinitrotoluenes, which have vicinal nitro groups on their arene structure. Non-specific anaerobic reduction of dinitrotoluenes by the intestinal bacterium L. lactis strain 27 differentiated the extent of reduction of DNTs according to the substitutional position of the nitro groups and produced in vitro more toxic dinitroazoxytoluenes, suggesting that anaerobic biotransformation of dinitrotoluenes could increase environmental risk.     

The oldest known tracks of web-footed birds from the Lower Cretaceous of South Korea

 We describe the oldest tracks of web-footed birds from the Early Cretaceous in South Korea. The tracks are characterized by a wide divarication angle and a long reversed hallux. The web is semipalmate and restricted to the proximal portion of the three forward digits. The tracks from the Early Cretaceous in South Korea are smaller than those of the Late Cretaceous, therefore confirming the trend of size increasing in the early evolution of birds as shown by skeletal fossils. The discovery of web-footed tracks with abundant non-web-footed tracks indicates that there was a considerable diversification of shore birds as early as the Early Cretaceous. Received: 4 November 1999 / Accepted in revised form: 28 February 2000     

Impact Modeling of Sewage Discharge From Georgetown of Penang, Malaysia on Coastal Water Quality

Currently about 200,000 persons of the Penang Georgetown population is served by a sewerage system which conveys the raw sewage to an open channel flume in Jelutong for discharge into the Western Channel. This has resulted in the degradation of coastal water quality in the affected areas. Therefore, there exists an urgent need to look for other alternatives for sewage treatment and disposal. This paper presents the results of computer simulations on the impacts of sewage discharge on Penang coastal waters under two treatment and disposal options. The preferred option is a conventional activated sludge treatment system capable of treating the sewage to secondary level with a submerged outfall to the Western Channel for the disposal of the treated effluent. The results of computer simulations show that the quality of coastal waters, other than in the immediate vicinity of the discharge point, would be able to achieve the Malaysian proposed criterion for recreational waters up to year 2020.     

Determination and speciation of heavy metals in sediments of the Juru River,Penang, Malaysia

The Juru River flows through largely urbanized areas and is grossly polluted by domestic wastes and discharges from pig farms. Other than carrying highly polluting organic materials, these wastes are also contaminated with heavy metals. To ascertain the extent of heavy metal pollution in the river, total and non-residual concentrations of Cu, Pb, Zn, Mn and Fe in sediment samples collected along the river were determined. The results indicate that both the total and non-residual metal concentrations in sediments can successfully be used to identify heavy metal pollution sources. The speciation of Zn, Mn and Fe in the sediment samples were investigated using a sequential leaching technique which identifies the elements among six operationally defined host fractions: (1) exchangeable, (2) carbonate and surface-associated, (3) easily reducible, (4) moderately reducible, (5) bound to organic matter and sulphides and (6) residual. The results indicate that Zn is mainly associated with the reducible fractions. Zn and Fe found in the moderately reducible fraction are significantly correlated, indicating that iron oxides is the preferred host phase by Zn.     

Characterization of ISO 14001 implementation

Environmental degradation caused by human activities is of concern to society, government, industry, companies, and the people who are able to enjoy improved lifestyles because of industrial activities. However, all of these parties also have a responsibility to support and conserve the environment and act responsibly toward the earth. This article, which includes a systematic literature review and draws upon the authors’ practical experience, summarizes the benefits, motives, and difficulties in implementing environmental management systems using the International Organization for Standardization's (ISO) 14001 framework.