Chien-Jung Tien

Partitioning of aromatic and oxygenated constituents into water from regular and ethanol-blended gasolines

Variability in gasoline-water partitioning of major aromatic constituents (benzene, toluene, ethylbenzene, and xylenes (BTEX)) and methyl tert-butyl ether (MTBE) were examined for regular and ethanol-blended gasolines. By use of a two-phase liquid-liquid equilibrium model, the distribution of nonpolar solutes between fuel phase and water was related to principles of equilibrium. The models derived using Raoults law convention for activity coefficients and liquid solubility is presented. The observed inverse log-log linear dependence of K(fw) values on aqueous solubility, could be well predicted by assuming gasoline to be an ideal solvent mixture. Oxygenated additives (i.e., ethanol and MTBE), in the low percent range (below 5%), were shown to have minimal or negligible cosolvent effects on hydrocarbon partitioning. In the case of high fuel-to-water ratio (e.g., 1:1) or near contaminant source zone, the cosolvent effect of oxygenated gasoline with high content of ethanol (e.g., E85) will be environmentally significant.

Biodegradation of carbamate pesticides by natural river biofilms in different seasons and their effects on biofilm community structure.

This study investigated the ability of natural river biofilms from different seasons to degrade the carbamate pesticides methomyl, carbaryl and carbofuran in single and multiple pesticide systems, and the effects of these pesticides on algal and bacterial communities within biofilms. Spring biofilms had the lowest biomass of algae and bacteria but showed the highest methomyl degradation (>99%) and dissipation rates, suggesting that they might contain microorganisms with high methomyl degradation abilities. Degradation of carbofuran (54.1-59.5%) by biofilms in four seasons was similar, but low degradation of carbaryl (0-27.5%) was observed. The coexistence of other pesticides was found to cause certain effects on pesticide degradation and primarily resulted in lower diversity of diatoms and bacteria than when using a single pesticide. The tolerant diatoms and bacteria potentially having the ability to degrade test pesticides were identified. River biofilms could be suitable biomaterials or used to isolate degraders for bioremediating pesticide-contaminated water.

Development of river biofilms on artificial substrates and their potential for biomonitoring water quality

This study conducted several approaches to determine development and succession of different types of biofilms (i.e., colonization and accumulation biofilms). Changes in total metabolic activity, bacterial and algal composition within different biofilms from two river ecosystems were analyzed. They were related to water quality parameters in order to assess major factors influencing biofilm growth. Significant differences in chlorophyll a concentrations in biofilms and water between two rivers were due to differences in light intensity, water current velocity, and turbidity. Colonization of epilithic algae in biofilms mainly resulted from high levels of nutrients (up to 2.8 mgL(-1) of phosphate) and water chlorophyll a, and may be caused by attachment of planktonic algae. However, epilithic algae may also serve as the source of planktonic algae. Oxidizable substrates measured as chemical oxygen demand were found to directly increase bacterial growth or indirectly affect growth a week later. One-month colonization biofilms were the most sensitive to change of water quality, and had the greatest number of significant relationships to physico-chemical and biological parameters among three types of biofilms. This suggested that 1-month colonization biofilms were applicable for biomonitoring water quality.

Assessing the toxicity of organophosphorous pesticides to indigenous algae with implication for their ecotoxicological impact to aquatic ecosystems

This study aimed to determine the toxicity of three organophosphorous pesticides, chlorpyrifos, terbufos and methamidophos, to three indigenous algal species isolated from local rivers and algal mixtures. The diatom Nitzschia sp. (0.30–1.68 mg L−1 of EC50 -the estimated concentration related to a 50% growth reduction) and the cyanobacteria Oscillatoria sp. (EC50 of 0.33–7.99 mg L−1) were sensitive to single pesticide treatment and the chlorophyta Chlorella sp. was the most tolerant (EC50 of 1.29–41.16 mg L−1). In treatment with the mixture of three pesticides, Chlorella sp. became the most sensitive alga. The antagonistic joint toxic effects on three indigenous algae and algal mixtures were found for most of the two pesticide mixtures. The results suggested that mixture of pesticides might induce the detoxification mechanisms more easily than the single pesticide. The synergistic interactions between terbufos and methamidophos to algal mixtures and between methamidophos and chlorpyrifos to Nitzschia sp. indicated methamidophos might act as a potential synergist. Differential sensitivity of three families of algae to these pesticides might result in changes in the algal community structures after river water has been contaminated with different pesticides, posing great ecological risk on the structure and functioning of the aquatic ecosystem.

Partitioning of polynuclear aromatic hydrocarbons into water from biodiesel fuel mixtures

Environmental context. The dwindling fossil fuel sources have led to a major interest in expanding the use of bioenergy. While biodiesel is moving towards the mainstream as an alternative source of energy, a thorough understanding of the potential impact and risk posed by spills of biodiesel and biodiesel fuel mixtures should be obtained. We present new data here that will allow the prediction of biodiesel behaviour and the extent of contamination in soils and groundwater in the event of such a spill. Abstract. Partition coefficients of polynuclear aromatic hydrocarbons (PAHs) between biodiesel fuel mixtures (i.e. B1, B5, and B20) and water were determined by the frequently applied estimation method of Raoult’s law. The experimental partition coefficients were compared with calculation by polyparameter linear free energy relationship (PP-LFER) approaches. Deviations from poor recovery of PAHs from the aqueous phase in partition experiments and parameters in the PP-LFER equation are discussed. The results suggest that the extent of deviation from ideal behaviour for biodiesel–water partitioning is relatively small (i.e. errors remain within a factor of two). The concentrations of PAHs in water in equilibrium with these biodiesel fuel mixtures, estimated from the model presented, may be considered as a reasonable approximation for most field-scale applications.

Epidemiological, clinical and climatic characteristics of dengue fever in Kaohsiung City, Taiwan with implication for prevention and control

Background The early identification of dengue infection is essential for timely and effective quarantine and vector control measures for preventing outbreaks of the disease. Kaohsiung City is responsible for most of the dengue cases in Taiwan. Thus, this study aims to identify major factors involved in the prevalence of dengue fever by analyzing the epidemiological and clinical characteristics, and to establish associations between weather parameters and dengue occurrence in this City. Methods A retrospective study was conducted with 3,322 confirmed dengue cases. Appropriate statistical methods were used to compare differences and correlations between dengue occurrence and demographic, clinical and weather parameters. Results The outbreak of dengue fever was found to be initiated by imported cases of dengue viruses from other endemic countries. Most of the confirmed cases were not reported to the health authority during the first visit to a doctor, and it took a median of 5 days after the appearance of the first syndromes for medical personnel to report suspected dengue cases. Accordingly, Aedes mosquitoes would have enough time to be infected and transmit the dengue virus. The diagnosis and notification criteria should not only include common symptoms of fever, myalgia, headache, skin rash and arthralgia, but should also be adjusted to include the most frequent symptoms of loss of appetite and feeling thirsty to shorten the notification time. Significantly positive correlations were found between the number of confirmed cases and weather parameters (i.e., temperature, rainfall and relative humidity) at a time lag of 1 month and 2 months. The predictive models for dengue occurrence using these three parameters at a 2-month lag time were established. Conclusions The surveillance of imported cases, adjustment of notification criteria and application of climatic predictive models would be helpful in strengthening the dengue early warning surveillance system.