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101.
Chiang CT Chang TK Hwang YH Su CC Tsai KY Yuan TH Lian IeB 《Environmental geochemistry and health》2011,33(5):469-476
The growing incidence of oral cancer (OC) in Taiwan has become a crucial public health concern. In particular, Changhua, a
county in central Taiwan, carries persistently high OC incidence rate, with an alarmingly high male/female ratio of OC incidence.
Previous epidemiological studies had found that the incidence is spatially correlated with the level of soil content to certain
heavy metals in the central Taiwan area. Soil and the human body both intake environmental heavy metals, which can be absorbed
through various ways. The soil metal concentration is an index of possible environmental exposure to heavy metal, and the
blood metal concentration somewhat reflects the level of the exposure on the human body. Metallic carcinogen is likely to
generate free radicals and play a role in many cancers, and many studies had reported that environmental exposure to heavy
metals is an important risk factor for developing cancer. Studies on animals showed that chronic intake of chromium (Cr) could
induce OC. This study aims to explore the association between the Cr concentration in the farm soil and in the blood of OC
patients. We recruited 79 OC patients from Changhua County, with their lifestyle being adjusted in regression analysis. The
results showed that the Cr concentration in the blood of OC patients is significantly higher than the background value, and
is positively associated with the Cr concentration in the soil surrounding their residence (p-value < 0.023). Because Changhua County is only with moderate prevalence of the known OC habitual risk factors, an environmental
factor related to heavy metal Cr exposure is suspected. Future investigations may verify the causal relation between Cr and
OC. 相似文献
102.
Effects of oceanic and terrestrial sediment suspensions on the behavioral traits activity, colony expansion, and mucus formation
of the gorgonian octocoral Subergorgia suberosa (Pallas, 1766) were studied in the laboratory. Increased sediment concentration significantly changed the logits of activity
indices (as colony expansion) and was correlated with decreased activity. For both sources of sediments, the activity index
decreased as the concentration of sediment increased. The level of decrease was more significance for terrestrial sediments.
The activity index showed no clear time pattern for the control group, but a decrease over time occurred in both sediment
treatment groups. Activity change was linearly correlated with exposure time and concentration of terrestrial and ocean sediments.
The activity indices of polyps were negatively correlated with the formation of mucus sheets (correlation = −0.536, p = 0.048). For both sources of sediments, the frequency of mucus sheet formation (MSF) increased with sediment concentration.
Increases in terrestrial sediment loads resulted in more striking effects. The probability for MSF under different sediment
groups at different concentrations over time was modeled by regressions. Frequency of polyp activity is suggested as a suitable
biomarker to monitor the effects of sedimentation stress. 相似文献
103.
Benefits of Bt cotton counterbalanced by secondary pests? Perceptions of ecological change in China 总被引:1,自引:0,他引:1
Jennifer H. Zhao Peter Ho Hossein Azadi 《Environmental monitoring and assessment》2011,173(1-4):985-994
In the past, scientific research has predicted a decrease in the effectiveness of Bt cotton due to the rise of secondary and other sucking pests. It is suspected that once the primary pest is brought under control, secondary pests have a chance to emerge due to the lower pesticide applications in Bt cotton cultivars. Studies on this phenomenon are scarce. This article furnishes empirical evidence that farmers in China perceive a substantial increase in secondary pests after the introduction of Bt cotton. The research is based on a survey of 1,000 randomly selected farm households in five provinces in China. We found that the reduction in pesticide use in Bt cotton cultivars is significantly lower than that reported in research elsewhere. This is consistent with the hypothesis suggested by recent studies that more pesticide sprayings are needed over time to control emerging secondary pests, such as aphids, spider mites, and lygus bugs. Apart from farmers?? perceptions of secondary pests, we also assessed their basic knowledge of Bt cotton and their perceptions of Bt cotton in terms of its strengths and shortcomings (e.g., effectiveness, productivity, price, and pesticide use) in comparison with non-transgenic cotton. 相似文献
104.
Jong Ho Kim Byoung Kyu Kwak Chee Burm Shin Won Jin Jeon Hyeon-Soo Park Sun Woo Lee Kyunghee Choi Woon Gi Lee Jun Hee Lee Sun Ho Baek Jongheop Yi 《Environmental Modeling and Assessment》2011,16(3):265-281
A local-scale spatially refined multimedia fate model (LSRMFM) was developed to evaluate in detail the multimedia transport of organic compounds at a spatial level. The model was derived using a combination of an advection?Cdispersion?Creaction partial differential equation, a steady-state multimedia fugacity model, and a geographical information system. The model was applied to predicting four major volatile organic compounds that are produced as emissions (benzene, toluene, xylene, and styrene) in an urban and industrial area (the 50?×?50-km area was divided into 0.5?×?0.5-km segments) in Korea. To test the accuracy of the model, the LSRMFM was used to predict the extent of dispersion and the data compared with actual measured concentrations and the results of a generic multimedia fate model (GMFM). The results indicated that the method developed herein is appropriate for predicting long-term multimedia pollution. However, the comparison study also illustrated that the developed model has some limitations (e.g., steady-state assumption) in terms of explaining all the observed concentrations, and additional verification and study (e.g., validation using a large observed data set, integration with a more accurate runoff model) would be desirable. In comparing LSRMFM and GMFM, discrepancies between the LSRMFM and GMFM outputs were found, as the result of geographical effects, even though the environmental parameters were identical. The geographical variation for LSRMFM output indicated the existence of considerable local human and ecological risks, whereas the GMFM output indicated less average risk. These results demonstrate that the model has the potential for improving the management of pollutant levels under these refined spatial conditions. 相似文献
105.
Allan Gomez-Flores Gukhwa Hwang Sadia Ilyas Hyunjung Kim 《Frontiers of Environmental Science & Engineering》2022,16(3):31
106.
Tae Won Lee Michael J. Miller Hak Bin Hwang Sam Wouthuyzen Katsumi Tsukamoto 《Marine Biology》2008,153(3):285-295
Leptocephali of the widely distributed tropical marine eels of the genus Kaupichthys (family Chlopsidae) were collected around Sulawesi Island during a sampling survey in the Indonesian Seas in late September
and early October 2002, and the otolith microstructure of 24 of the 59 specimens captured was examined to learn about the
larval growth rates and spawning times of these small sized eels. Leptocephali ranging in size from 25 to 60 mm were collected
in Makassar Strait and the Celebes Sea, but they were most abundant in the semi-enclosed Tomini Bay of northeast Sulawesi
Island. The Kaupichthys leptocephali examined had 39–161 otolith growth increments. Their back-calculated hatching dates indicated that five age
groups were present and each group appeared to have been spawned around the full moon of previous months. Average growth rate
estimates of the first two age groups were 0.65 and 0.54 mm/day for the 27.4–30.4 and 37.6–45.6 mm age classes. The growth
rates of the oldest three age groups (52.0–60.8 mm) appeared to have slowed down after they reached their approximate maximum
size. An increase in increment widths at the outer margin of the otoliths of those larger than 53 mm suggested that the process
of metamorphosis had begun even though there were few external morphological changes indicating metamorphosis. It is hypothesized
that chlopsid leptocephali have an unusually short gut that may not need to move forward during early metamorphosis. The presence
of four age classes in Tomini Bay suggests that the Togian Islands region may be productive habitats for Kaupichthys juveniles and adults. 相似文献
107.
Gael Dur Sami Souissi David Devreker Vincent Ginot François G. Schmitt Jiang-Shiou Hwang 《Ecological modelling》2009
Limited empirical studies have elucidated the daily egg production and associated reproductive processes of egg bearing copepod. Herein, we present an individual-based model which constitutes a realistic representation of the reproduction in egg bearing copepods. The model has been parameterized using an extensive set of experimental data obtained from the literature and from the laboratory and field experiments on the estuarine copepod Eurytemora affinis. The proposed model takes into account the adult female longevity, the clutch size and interclutch duration, which is a function of egg maturation time and latency time required by the female after egg hatching to produce a new clutch. The embryonic development time and hatching success are also taken into account. The effect of temperature on the means and variances of above-mentioned reproductive parameters has been also incorporated. A multi agent system based generic platform “Mobidyc” has been used to generate and calibrate the model. The model demonstrates the reproductive parameters of females of E. affinis which is validated through individual based experiments. Temperature specific simulations provide a dynamical explanation of temperature effect on the cumulative egg production. The daily survival principally affects the number of clutches produced per female during its life span. The results obtained in the present study by combining temperature and survival effects reveal the relatively greater importance of the first factor on the daily egg production of egg-carrying copepods. The present model is generic and hence easily applicable to other animals with comparable reproductive strategy. 相似文献
108.
Hwang IH Aoyama H Matsuto T Nakagishi T Matsuo T 《Waste management (New York, N.Y.)》2012,32(3):410-416
Hydrothermal treatments using subcritical water (HTSW) such as that at 234 °C and 3 MPa (LT condition) and 295 °C and 8 MPa (HT condition) were investigated to recover solid fuel from municipal solid waste (MSW). Printing paper, dog food (DF), wooden chopsticks, and mixed plastic film and sheets of polyethylene, polypropylene, and polystyrene were prepared as model MSW components, in which polyvinylchloride (PVC) powder and sodium chloride were used to simulate Cl sources.While more than 75% of carbon in paper, DF, and wood was recovered as char under both LT and HT conditions, plastics did not degrade under either LT or HT conditions. The heating value (HV) of obtained char was 13,886-27,544 kJ/kg and was comparable to that of brown coal and lignite. Higher formation of fixed carbon and greater oxygen dissociation during HTSW were thought to improve the HV of char.Cl atoms added as PVC powder and sodium chloride to raw material remained in char after HTSW. However, most Cl originating from PVC was found to converse into soluble Cl compounds during HTSW under the HT condition and could be removed by washing.From these results, the merit of HTSW as a method of recovering solid fuel from MSW is considered to produce char with minimal carbon loss without a drying process prior to HTSW. In addition, Cl originating from PVC decomposes into soluble Cl compound under the HT condition. The combination of HTSW under the HT condition and char washing might improve the quality of char as alternative fuel. 相似文献
109.
Kun‐Yeun Han Sang‐Ho Kim Deg‐Hyo Bae 《Journal of the American Water Resources Association》2001,37(3):695-708
ABSTRACT: This study developed a QUAL2E‐Reliability Analysis (QUAL2E‐RA) model for the stochastic water quality analysis of the downstream reach of the main Han River in Korea. The proposed model is based on the QUAL2E model and incorporates the Advanced First‐Order Second‐Moment (AFOSM) and Mean‐Value First‐Order Second‐Moment (MFOSM) methods. After the hydraulic characteristics from standard step method are identified, the optimal reaction coefficients are then estimated using the Broyden‐Fletcher‐Goldfarb‐Shanno (BFGS) method. Considering variations in river discharges, pollutant loads from tributaries, and reaction coefficients, the violation probabilities of existing water quality standards at several locations in the river were computed from the AFOSM and MFOSM methods, and the results were compared with those from the Monte Carlo method. The statistics of the three uncertainty analysis methods show that the outputs from the AFOSM and MFOSM methods are similar to those from the Monte Carlo method. From a practical model selection perspective, the MFOSM method is more attractive in terms of its computational simplicity and execution time. 相似文献
110.
Bioabsorbable Soy Protein Plastic Composites: Effect of Polyphosphate Fillers on Biodegradability 总被引:8,自引:0,他引:8
Alan H. Tkaczyk Joshua U. Otaigbe Kai-Lai G. Ho 《Journal of Polymers and the Environment》2001,9(1):19-23
The use of biodegradable polymers made from renewable agricultural products such as soy protein isolate has been limited by the tendency of these materials to absorb moisture. A straightforward approach for controlling the inherent water absorbency of the biodegradable polymers involves blending special bioabsorbable polyphosphate fillers, biodegradable soy protein isolate, plasticizer, and adhesion promoter in a high-shear mixer followed by compression molding. The procedure yields a relatively water-resistant, biodegradable soy protein polymer composite, as previously reported. The aim of the present study is to determine the biodegradability of the new polyphosphate filler/soy protein plastic composites by monitoring the carbon dioxide released over a period of 120 days. The results suggest that the composites biodegrade satisfactorily, with the fillers having no significant effect on the depolymerization and mineralization of the soy protein plastic, processes that would otherwise result in nonbiodegradable composites. Further, the results indicate that the biodegradation and useful service life of these biocomposites may be controlled by changing the filler concentration, making the biocomposites useful in applications in which the control of water resistance and biodegradation is critical. 相似文献