Environmental 238U and 232Th concentration measurements in an area of high level natural background radiation at Palong, Johor, Malaysia

Concentrations of uranium-238 and thorium-232 in soil, water, grass, moss and oil-palm fruit samples collected from an area of high background radiation were determined using neutron activation analysis (NAA). U-238 concentration in soil ranged from 4.9 mg kg(-1) (58.8 Bq kg(-1)) to 40.4 mg kg(-1) (484.8 Bq kg(-1)), Th-232 concentration ranged from 14.9 mg kg(-1) (59.6 Bq kg(-1)) to 301.0 mg kg(-1) (1204 Bq kg(-1)). The concentration of U-238 in grass samples ranged from below the detection limit to 0.076 mg kg(-1) (912 mBq kg(-1)), and Th-232 ranged from 0.008 mg kg(-1) (32 mBq kg(-1)) to 0.343 mg kg(-1) (1.372 Bq kg(-1)). U-238 content in water samples ranged from 0.33 mg kg(-1) (4.0 Bq L(-1)) to 1.40 mg kg(-1) (16.8 Bq L(-1)), and Th-232 ranged from 0.19 mg kg(-1) (0.76 Bq L(-1)) to 0.66 mg kg(-1) (2.64 Bq L(-1)). It can be said that the concentrations of environmental U-238 and Th-232 in grass and water samples in the study area are insignificant. Mosses were found to be possible bio-radiological indicators due to their high absorption of the heavy radioelements from the environment.     

Growth inhibition in Japanese medaka (Oryzias latipes) fish exposed to tetrachloroethylene

A recent study in our laboratory has demonstrated that tetrachloroethylene (TCE) is acutely toxic to Japanese medaka (Oryzias latipes) larvae with a 96 hr-LC50 of 18 (17-19) mg/mL (Spencer et al., 2002). In the present study we hypothesize that TCE exposure induces a developmental effect in Japanese medaka. Growth and age specific sensitivity of Japanese medaka larvae were studied with four age groups (7, 14, 21 and 28 days old) to determine tetrachloroethylene effects on these parameters. The medaka larvae were exposed for 96 hours in a single concentration (10 mg/mL) of TCE. The toxic endpoints evaluated were larvae weight, length, water content and protein concentration. The study revealed that exposure of medaka larvae to this sub-acute concentration of TCE significantly reduced length and weight in the treated group. The difference in growth between control and treated groups was more obvious in age versus length, than in age versus weight. The dry weight-fresh weight ratio (dw/fw) was shown to be higher in the control group. Water content in TCE-treated medaka was higher than in the control group, and younger fry had more water content than older ones. A higher protein concentration was also observed in TCE-treated medaka compared to the control group. These results indicate that TCE has a profound effect on the growth and development of Japanese medaka larvae.     

Bioaccumulation and physiological effects of mercury in Sesbania drummondii

The accumulation of mercury and its effect on growth, photosynthesis and antioxidative responses were studied in Sesbania drummondii seedlings. Mercury concentration in shoots as well as in the roots increased with increasing Hg concentrations in the growth solution. The accumulation of Hg was more in roots than shoots. At 100 mg l-1 Hg concentration, shoots accumulated 998 mg Hg kg -1 dry weight (dw) while roots accumulated 41,403 mg Hg kg-1 dw. Seedlings growth was not significantly affected at lower concentrations of Hg. A concentration of 100 mg l-1 Hg inhibited growth by 36.8%, with respect to control. Photosynthetic activity was assessed by measuring chlorophyll a fluorescence by determination of Fv/Fm and Fv/Fo values. Photosynthetic integrity was not affected up to 50 mg l-1 Hg concentration, however, concentrations higher than 50 mg l-1 affected photosynthetic integrity. Sesbania responded to Hg induced oxidative stress by modulating non-enzymatic antioxidants [glutathione (GSH) and non-protein thiols (NPSH)] and enzymatic antioxidants: superoxide dismutase (SOD), ascorbate peroxidase (APX) and glutathione reductase (GR). Glutathione content and GSH/GSSG ratio increased up to a concentration of 50 mg l-1 while slight down at 100 mg l-1 Hg. The content of NPSH significantly increased with increasing Hg concentrations in the growth medium. The activities of antioxidative enzymes, SOD, APX and GR followed the same trends as antioxidants first increased up to a concentration of 50 mg l-1 Hg and then slight decreased. The results of present study suggest that Sesbania plants were able to accumulate and tolerate Hg induced stress using an effective antioxidative defense mechanisms.     

Fisheries sustainability assessment and sensitivity analysis: an illustration

Using a modified Ecologically Sustainable Development (ESD) framework, this paper assesses progress towards sustainability over time with a case study of the demersal trawl fishery of Oman, which has been transformed and turned into the coastal fishery after the trawl ban. A multi-criteria decision analysis method is used for ranking the years and deciding on the best performing year under five alternative scenarios related to the core components involving humans and the environment. Under the environment component, the year 2001 stood out as the best across all scenarios. The combined results also echoed the same in four out of five scenarios. With reference to progress towards sustainability during the study period, no clear positive year-to-year trend was observed from the overall results. The analysis of the S2 scenario revealed that the closed fishing season during 1998–2001 yielded a positive spill-over effect on the local economy. The results from a comparative analysis indicated that the strengths (weaknesses) of the year 2001 were predominantly associated with the environment (human) component, and thereby, reflecting a comparatively higher conservation outcome in the year 2001. The findings from the comparative analysis would guide fishery managers in designing appropriate strategies for improving weaknesses of the preferred option and reducing the inter-scenario risk by combining positive features of the second-best option. The framework outlined in the present paper can be used to guide the sustainability assessment of other local fisheries (for instance, the lobster, abalone, and shrimp fisheries) including the recently developed coastal fishery.

     

Biodesulfurization of refractory sulfur compounds in petro-diesel by a novel hydrocarbon tolerable strain Paenibacillus glucanolyticus HN4

Environmental Science and Pollution Research - One of the main precursors of air pollution and acid rains is the presence of the recalcitrant thiophenic compounds, for example dibenzothiophene...     

Impacts of and adaptation to climate change on the oil palm in Malaysia: a systematic review

Environmental Science and Pollution Research - The interaction and the interplay of climate change with oil palm production in the Southeast Asia region are of serious concern. This particularly...     

Modeling of flow and contaminant transport in coupled stream-aquifer systems

This paper describes an integrated approach for modeling flow and contaminant transport in hydraulically connected stream-aquifer systems. The code, FTSTREAM, extended the capabilities of the ground-water model, FTWORK, to incorporate chemical fate and transport in streams. Flow in the stream network is modeled as an unsteady, spatially varying flow, while transport modeling is based on a one-dimensional advection-dispersion equation. In addition to sorption and decay during transport in ground water, the model incorporates volatilization, settling and decay during transport in surface water. The interaction between surface water and ground water is accommodated by a leakage term and is implemented in the model using an iterative Picard-type procedure to ensure mass conservation across the interface between the two systems. The modeling approach is used to simulate contaminant transport in the Mad River, Ohio, which is hydraulically connected to a buried valley aquifer of sand and gravel outwash. The river is a receiving stream in the upstream part of the modeled area. Downstream, heavy pumping from a municipal well field causes the river to become a loosing stream. Induced infiltration from the river is responsible for a considerable portion of the well yield. The flow and transport model, developed for this study, simulates coupling between flow in the aquifer and the river. Hypothetical sources of contamination are introduced at selected locations in the upstream portion of the aquifer. The model is then used to simulate the expected transport in both the aquifer and the stream. A series of simulations elucidates the role of the river in facilitating the transport of the hypothetical contaminants in ground water and surface water. Effect of sorption, retardation and volatilization on contaminant transport is also examined for the case of the volatile organic compounds.     

Adsorption kinetics and modeling of H2S by treated waste oil fly ash

Waste oil fly ash (OFA) collected from disposal of power generation plants was treated by physicochemical activation technique to improve the surface properties of OFA. This synthesized material was further used for potential hydrogen sulfide (H₂S) adsorption from synthetic natural gas. The raw OFA was basically modified with a mixture of acids (20% nitric acid [HNO₃] and 80% phosphoric acid [H₃PO₄]), and it was further treated with 2 M potassium hydroxide (KOH) to enhance the surface affinity as well as surface area of synthesized activated carbon. Correspondingly, it enhanced the adsorption of H₂S. Crystallinity, surface morphology, and pore volume distribution of prepared activated carbon were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), and Brunauer-Emmett-Teller (BET) analyses. Fourier transform infrared (FTIR) study was also performed to identify the functional groups during different synthesis stages of modified activated carbon. The Langmuir, Freundlich, Sips, and dual-site Langmuir (DSL) models were used to study the kinetic and breakthrough behavior of H₂S adsorption over alkali-modified activated carbon. Modeling results of isotherms indicated that OFA has dual sites with high and low affinity for H₂S adsorption. The Clark model, Thomas model, and Yoon-Nelson model were used to examine the effects of flow rate and inlet concentration on the adsorption of H₂S. Maximum uptake capacity of 8.5 mg/g was achieved at 100 ppm inlet concentration and flow rate of 0.2 L/min.

Implications: Utilization of worthless oil fly ash from power plant is important not only for cleaning the environment but also for solid waste minimization. This research scope is to eradicate one pollutant by using another pollutant (waste ash) as a raw material. Chemical functionalization of synthesized activated carbon from oil fly ash would lead to attachment of functional groups of basic nature to attract the acidic H₂S. Such type of treatment can enhance the uptake capacity of sorbent several times.     

Baseline study of methane emission from open digesting tanks of palm oil mill effluent treatment

Anthropogenic release of greenhouse gases, especially CO₂ and CH₄ has been recognized as one of the main causes of global warming. Several measures under the Kyoto Protocol 1997 have been drawn up to reduce the greenhouse gases emission. One of the measures is Clean Development Mechanisms (CDM) that was created to enable developed countries to cooperate with developing countries in emission reduction activities. In Malaysia, palm oil industry particularly from palm oil mill effluent (POME) anaerobic treatment has been identified as an important source of CH₄. However, there is no study to quantify the actual CH₄ emission from the commercial scale wastewater treatment facility. Hence, this paper shall address the CH₄ emission from the open digesting tanks in Felda Serting Hilir Palm Oil Mill. CH₄ emission pattern was recorded for 52 weeks from 3600 m³ open digesting tanks. The findings indicated that the CH₄ content was between 13.5% and 49.0% which was lower than the value of 65% reported earlier. The biogas flow rate ranged between 0.8 l min⁻¹ m⁻² and 9.8 l min⁻¹ m⁻². Total CH₄ emission per open digesting tank was 518.9 kg day⁻¹. Relationships between CH₄ emission and total carbon removal and POME discharged were also discussed. Fluctuation of biogas production was observed throughout the studies as a result of seasonal oil palm cropping, mill activities, variation of POME quality and quantity discharged from the mill. Thus only through long-term field measurement CH₄ emission can be accurately estimated.