Colin S. Chen

Application of real-time PCR, DGGE fingerprinting, and culture-based method to evaluate the effectiveness of intrinsic bioremediation on the control of petroleum-hydrocarbon plume.

Real-time polymerase chain reaction (PCR), denaturing gradient gel electrophoresis (DGGE), and the culture-based method were applied in the intrinsic bioremediation study at a petroleum-hydrocarbon contaminated site. The genes of phenol hydroxylase (PHE), ring-hydroxylating toluene monooxygenase (RMO), naphthalene dioxygenase (NAH), toluene monooxygenase (TOL), toluene dioxygenase (TOD), and biphenyl dioxygenase (BPH4) were quantified by real-time PCR. Results show that PHE gene was detected in groundwater contaminated with benzene, toluene, ethylbenzene, xylene isomers (BTEX) and methyl tert-butyl ether (MTBE), and this indicates that intrinsic bioremediation occurred at this contaminated site. Results from DGGE analyses reveal that the petroleum-hydrocarbon plume caused the variation in microbial communities. In this study, MTBE degraders including Pseudomonas sp. NKNU01, Bacillus sp. NKNU01, Klebsiella sp. NKNU01, Enterobacter sp. NKNU01, and Enterobacter sp. NKNU02 were isolated from the contaminated groundwater using the cultured-based method. Results from MTBE biodegradation experiment show that the isolated bacteria were affected by propane. This indicates that propane may influence the metabolic pathway of MTBE by these bacteria. Knowledge and comprehension obtained from this study will be helpful in evaluating the occurrence and effectiveness of intrinsic bioremediation on the remediation of petroleum-hydrocarbon contaminated groundwater.

The potential role of water quality parameters on occurrence of nonylphenol and bisphenol A and identification of their discharge sources in the river ecosystems

Nonylphenol (NP) and bisphenol A (BPA) have attracted great attention due to their estrongenic activities and occurrence in different environments. This study investigated concentrations of NP and BPA in water and sediments of 16 major rivers in Taiwan to determine their association with water quality parameters on their distribution. The sources of NP and BPA discharged into river environments were also identified. The results showed that concentrations of NP and BPA were in the range of 0.02-3.94 and 0.01-44.65μgL(-1) in water and 6.59-47797.69 and 0.37-491.54μgkg(-1) dry weight in sediments. High levels of NP and BPA in water and sediments were measured in sampling sites near highly industrialized and urbanized areas. Construction of the sewage system and wastewater treatment plant has decreased these chemicals discharged into Love River. Dilution effects and erosion of surface sediments in the high-flow season resulted in lower concentrations of NP and BPA detected in sediments of most rivers than those in the low-flow season. Occurrence characteristics of NP and BPA in water and sediments were mainly related to organic carbon contents in sediments and several water quality parameters such as dissolved oxygen, pH, concentrations of ammonia-nitrogen and total organic carbon in water. Effluents from NP/BPA-related factories appeared to be the major discharge sources of NP and BPA. Use and waste of BPA-containing products in household activity was the another discharge source of BPA, but handling NP-containing products became an important source of NP only in the low-flow season.

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.

Biodegradation of methyl tert-butyl ether (MTBE) by Enterobacter sp. NKNU02

We previously isolated and identified Enterobacter sp. NKNU02 as a methyl tert-butyl ether (MTBE)-degrading bacterial strain from gasoline-contaminated water. In this study, tert-butyl alcohol, acetic acid, 2-propanol, and propenoic acid were detected using gas chromatography/mass spectrometry when MTBE was degraded by rest cells of Enterobacter sp. NKNU02 cells. We also found that biodegradation of MTBE was decreased, but not totally inhibited in mixtures of benzene, toluene, ethylbenzene and xylene. The effects of MTBE on the biology of Enterobacter sp. NKNU02 were elucidated using 2D proteomic analysis. The cytoplasmic proteins isolated from these MTBE-treated and -untreated cells were carried out for proteomic analysis. Results showed that there were 6 differential protein spots and 8 differential protein spots, respectively, as compared to their corresponding control (without MTBE addition), at the indicated incubation times when 40% and 60% of 100 mg/L of MTBE had been removed, Among these proteins, nine were successfully identified with matrix-assisted laser desorption ionization-time of flight-mass spectrometry. Proteins identified included extracellular solute-binding protein, periplasmic-binding protein ytfQ, cationic amino acid ABC transporter, isocitrate dehydrogenase, cysteine synthase A, alkyl hydroperoxide reductase (AhpC), transaldolase, and alcohol dehydrogenase. Based on these differential proteins, we discuss the bacterial responses to MTBE at the molecular level.

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.

The major source and impact of phenyltin contamination on freshwater aquaculture clam Corbicula fluminea and wild golden apple snail Pomacea canaliculata

Environmental context. Phenyltin contamination is worldwide, and can be detrimental for aquatic ecosystems. Such contamination is largely due to the wide use of triphenyltin-based antifouling paints in the marine environment, but also to its use as fungicides and molluscicides in agriculture. This study provided the data to allow assessment of the accumulation potential of phenyltin compounds in molluscs, and established the correlation of phenyltin concentrations between biota and environmental matrices. Abstract. This study determined the concentrations of triphenyltin (TPT) and its degradation products, diphenyltin (DPT) and monophenyltin (MPT), in the aquaculture clam Corbicula fluminea and the wild golden apple snail Pomacea canaliculata. Sediments from irrigation ditches and clam aquaculture ponds, and soils from paddy fields were also analysed for these compounds in order to elucidate the sources and impact of phenyltin contamination. Considerably high levels of TPT were found in clams (<5.7–68.7 ng g–1 WW, wet weight), snails (ND (not determined)–1558.0 ng g–1 WW), and soils (ND–336.8 ng g–1 DW, dry weight), but not in sediments. The accumulation of phenyltin compounds in clams and snails was attributed to the spraying of triphenyltin-based pesticides in paddy fields. The higher levels of phenyltins accumulated in snails did not result in higher imposex levels, but caused a longer penis sheath length. The biota-sediment accumulation factor (BSAF) indicated that clams (2.3–6.9) had a higher bioaccumulative ability of TPT from sediments than snails (1.0–1.4). Relatively low levels of the hazard quotients of TPT (i.e. <1) suggested consumption of the aquaculture clam might not have a potential human health risk.

Effects of Cosolvent and Temperature on the Desorption of Polynuclear Aromatic Hydrocarbons from Contaminated Sediments of Chien-Jen River, Taiwan

This study evaluated the effects of the water-miscible cosolvent and temperature on the sorption-desorption of polynuclear aromatic hydrocarbons (PAHs) from contaminated sediments in Chien-Jen River, Taiwan. Sediment samples from five sampling stations of downstream section were utilized in this study. Phenanthrene and anthracene were selected as target compounds. The cosolvent effect on sorption of phenanthrene and anthracene was examined by the addition of various volume fractions of methanol (i.e., 0.3, 0.5, 0.7, and 0.9, respectively) in the sediment/water systems. The utility of the log-linear cosolvency model for predicting PAH sorption from solvent mixtures was evaluated. An inverse relationship was observed for sorption coefficients of phenanthrene and anthracene as a function of increasing cosolvent. The effect of temperature on sorption of phenanthrene and anthracene was conducted at temperature from 10°C to 40°C. The use of elevated temperatures in desorption experiments increased the PAH release from sediments. It was observed that sorption of phenanthrene and anthracene onto sediments decreased when temperature increased. The decrease of sorption coefficient of phenanthrene was more sensitive than that of anthracene. The magnitude of decreased sorption was attributed by the increased desorption rate constant, solubility, and heterogeneities of sediments.