Green oysters caused by copper pollution on the Taiwan coast

The first case of green oysters (Crassostrea gigas) broke out along the Charting mariculture area of south-western Taiwan in January 1986. The green color was found to be due to high copper content in the oyster tissue. Since then, a long-term survey around this area shows that total dissolved copper ranges from 4.99 to 23.6 microg/liter and particulate copper ranges from 1.09 to 5.51 microg/liter in sea-water. The green oysters collected from the Erhjin Chi estuary on 26 January, 1989 gave the highest copper content, 4401+/-79 ppm dry wt. Other green oyster cases were occasionally observed in the Hsiangsan and Anpin mariculture areas. Meanwhile, an experiment of copper accumulation in oysters was conducted at three stations (south-western Taiwan) for up to 90 days. Multiple regression analysis indicates that the food pathway may predominate in copper accumulation by green oysters. This bioaccumulation experiment shows that the total uptake of copper per oyster is an exponential function of exposure time for the first 2 weeks with an accumulation rate of 214 ppm Cu/day and then levels off. The average values of concentration factors for oysters (about 5 x 10(5)) were very close to steady-state values under the natural conditions at each station.     

WINTER HEAT BUDGET AND FRAZIL ICE PRODUCTION IN THE UPPER ST. LAWRENCE RIVER1

ABSTRACT: Winter heat budget and frazil ice production in the St. Lawrence River between the Ogdensburg-Prescott Boom and the Moses-Saunders Power Dam are analyzed. Contributions of each heat exchange component, and spatial distributions of heat exchange rates are calculated for three typical winters. Based on the calculated heat budget, the amount and distribution of frazil ice generated in the study reach is analyzed. The result of this study indicates that the thermal energy contained in the river water flowing into the study reach is a dominate factor in the heat budget analysis. The heat flux from the channel bottom accounts for an important portion of the total heat budget during the ice covered period.     

Dry deposition of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in ambient air

The PCDD/Fs in the ambient air associated with concentration and dry deposition flux of four seasons were characterized in rural area. The mean PCDD/F concentrations were 0.342, 0.221, 0.675, 0.741 pg m(-3) and the mean I-TEQ values were 0.027, 0.016, 0.024, 0.063 pg m(-3) in spring, summer, fall and winter, respectively. Ambient air in winter was higher by a factor of 3.4 and 3.9 for PCDD/F concentration and I-TEQ, respectively, than in summer. The study area is located in a Tropical region. Hence, domestic heating is not found in this area and is not responsible for the elevated winter concentration in comparison to other studies. A smooth plate with a sharp leading edge that is pointed into the wind by a wind vane was used for measuring dry deposition flux of PCDD/Fs. Atmospheric dry deposition fluxes of total PCDD/Fs were 140, 116, 137, and 207 pg m(-2)day(-1) in spring, summer, fall, and winter, respectively, and averaged approximately 150 pg m(-2)day(-1). The total dry deposition flux was found to decrease as the temperature increased. Calculated dry deposition velocities of total PCDD/Fs were 0.45, 0.52, 0.32 and 0.39 cm s(-1) in spring, summer, fall, and winter, respectively, and averaged 0.42 cm s(-1).     

Chromate reduction on humic acid derived from a peat soil--exploration of the activated sites on HAs for chromate removal

Humic substances are a major component of soil organic matter that influence the behavior and fate of heavy metals such as Cr(VI), a toxic and carcinogenic element. In the study, a repetitive extraction technique was used to fractionate humic acids (HAs) from a peat soil into three fractions (denoted as F1, F2, and F3), and the relative importance of O-containing aromatic and aliphatic domains in humic substances for scavenging Cr(VI) was addressed at pH 1. Spectroscopic analyses indicated that the concentrations of aromatic C and O-containing functional groups decreased with a progressive extraction as follows: F1>F2>F3. Cr(VI) removal by HA proceeded slowly, but it was enhanced when light was applied due to the production of efficient reductants, such as superoxide radical and H(2)O(2), for Cr(VI). Higher aromatic- and O-containing F1 fraction exhibited a greater efficiency for Cr(VI) reduction (with a removal rate of ca. 2.89 mmol g(-1) HA under illumination for 3 h). (13)C NMR and FTIR spectra further demonstrated that the carboxyl groups were primarily responsible for Cr(VI) reduction. This study implied the mobility and fate of Cr(VI) would be greatly inhibited in the environments containing such organic groups.     

Application of WRF-Chem to simulate air quality over Northern Vietnam

Environmental Science and Pollution Research - The WRF-Chem (Weather Research and Forecasting with Chemistry) model is implemented and validated against ground-based observations for meteorological...     

Organotin concentrations in three intertidal neogastropods from the coastal waters of Taiwan

This study was aimed to determine organotin concentrations in the muricids Thais clavigera, Thais tuberosa and Morula granulata on an island wide scale and to find an adequate bioindicator species for long-term monitoring purpose. Samples were collected from the coast of Taiwan and vicinity islands with organotin analysis by graphite furnace atomic absorption spectrophotometry. Because triphenyltin (TPT) could not be discriminated from tributyltin (TBT) by the extraction method, organotins were measured as TBT + TPT and total hexane extractable organotins. Severity of imposex in the muricid population samples expressed as relative penis size (RPS) indices were calculated and compared to determine a suitable bioindicator species. In T. clavigera, T. tuberosa and M. granulata, TBT + TPT were 17-157, 1-44 and 117-1343 ng Sn g(-1) dry wt, respectively. And total organotins varied in the range of 181 to 1125, 23 to 44 and 229 to 1402 ng Sn g(-1) dry wt, respectively. A positive correlation was found between TBT + TPT and total organotins in M. granulata (TBT + TPT = Total organotins x 1.01-110.79; R2=0.97; p<0.001). At the site of Dapaisha, total organotins in M. granulata was 10 times higher than in T. tuberosa (i.e. 242 versus 23 ng Sn g(-1) dry wt). No signs of imposex were found in T. tuberosa (a single site in two subsequent years) and in M. granulata (seven collection sites). The degree of imposex (RPS) of T. clavigera varied from 0.2 to 38.1%. The RPS indices from fishing harbors were not higher than from rocky shores and oyster culture sites. No correlation was found between RPS indices and concentrations of TBT + TPT or total organotins. M. granulata seemed to be insensitive to organotin pollution although organotins were also detected. Our results indicate that organotin pollution is wide spread in coastal waters of Taiwan and pollutants at least include butyltins and phenyltins. As a bioindicator species, T. clavigera is more appropriate than T. tuberosa and M. granulata to monitor organotin contamination.     

Gender differences in wayfinding in virtual environments with global or local landmarks

This study assesses gender differences in wayfinding in environments with global or local landmarks by analyzing both overall and fine-grained measures of performance. Both female and male participants were required to locate targets in grid-like virtual environments with local or global landmarks. Interestingly, the results of the two overall measures did not converge: although females spent more time than males in locating targets, both genders were generally equivalent in terms of corrected travel path. Fine-grained measures account for different aspects of wayfinding behavior and provide additional information that explains the divergence in overall measures; females spent less time traveling away from the target location, a higher proportion of time not traversing, and made more rotations when stopping than males did. Rather than unequivocally supporting male superiority in wayfinding tasks, both the overall and fine-grained measures partially indicate that males and females are differentially superior when using global and local landmark information, respectively. To summarize, males moved faster than females but did not necessarily navigate the spatial surroundings more efficiently. Each gender showed different strengths related to wayfinding; these differences require the application of both overall and fine-grained measures for accurate assessment.     

Profiles and removal efficiency of polycyclic aromatic hydrocarbons by two different types of sewage treatment plants in Hong Kong

Sewage discharge could be a major source of polycyclic aromatic hydrocarbons(PAHs) in the coastal waters. Stonecutters Island and Shatin Sewage Treatment Works(SCISTW and STSTW)in Hong Kong, adopted chemically enhanced primary treatment and biological treatment,respectively. This study aimed at(1) determining the removal efficiencies of PAHs,(2) comparing the capabilities in removing PAHs, and(3) characterizing the profile of each individual PAHs, in the two sewage treatment plants(STPs). Quantification of 16 PAHs was conducted by a Gas Chromatography. The concentrations of total PAHs decreased gradually along the treatment processes(from 301 ± 255 and 307 ± 217 ng/L to 14.9 ± 12.1 and 63.3 ± 54.1 ng/L in STSTW and SCISTW, respectively). It was noted that STSTW was more capable in removing total PAHs than SCISTW with average total removal efficiency 94.4% ± 4.12% vs. 79.2% ± 7.48%(p 0.05). The removal of PAHs was probably due to sorption in particular matter, confirmed by the higher distribution coefficient of individual and total PAHs in solid samples(dewatered sludge contained92.5% and 74.7% of total PAHs in SCISTW and STSTW, respectively) than liquid samples(final effluent-total contained 7.53% and 25.3% of total PAHs in STSTW and SCISTW, respectively).Despite the impressive capability of STSTW and SCISTW in removing PAHs, there was still a considerable amount of total PAHs(1.85 and 39.3 kg/year, respectively for the two STPs) being discharged into Hong Kong coastal waters, which would be an environmental concern.