Exposure of arc-furnace-plant workers to polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs)

This study aimed to evaluate serum polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) levels in electric-arc-furnace workers according to their corresponding occupational exposure. In addition, the ambient PCDD/Fs of the work environment were measured to provide additional support for the exposure and accumulation inside the electric arc furnace. The ambient PCDD/F concentrations inside the electric arc furnace were 1.557-1.917 pg-TEQ/Nm(3), 5-24 folds higher than those outside (0.080-0.385 pg-TEQ/N m(3)). In addition, higher average serum levels were measured in the workers with high occupational dioxin exposure (24.0 pg WHO-TEQ/g lipid) than in those with lower occupational dioxin exposure (13.8 pg WHO-TEQ/g lipid). Higher PCDFs/PCDDs ratios were found in serum samples from high-exposure groups than in low-exposure groups. The higher ratio of PCDFs/PCDDs was also found in ambient samples consistent with other metallurgical processes reported previously. Our results suggest that PCDD/Fs exposure exits in the smelting process of electric arc furnace, and the occupational hygiene should be taken more seriously concern in that workplace.     

Relationship between carbonaceous materials and polychlorinated biphenyls (PCBs) in the sediments of the Danshui River and adjacent coastal areas, Taiwan

Persistent organic pollutants, POPs (e.g., polychlorinated biphenyls) can seriously and deleteriously affect environmental quality and human health. These organic pollutants are exhibiting high affinities to solid phases and thus, quickly end up in sediments. To better understand the role of carbonaceous materials in the transport and distributions of POPs in terrestrial and near-shore environments, concentrations of PCBs and carbonaceous materials (including total organic carbon, black carbon and total carbohydrates), were determined in surface sediments of the Danshui River and nearby coastal areas, Taiwan. Total concentrations of PCBs in the sediments ranged from non-detectable to 83.9 ngg(-1), dry weight, with the maximum value detected near the discharge point of the marine outfall from the Pali Sewage Treatment Plant. These results suggest that the sewage treatment plant has discharged PCBs in the past and the concentrations are still high due to their persistence; alternatively, PCBs are still being discharged in the estuarine and near-shore environment of the Danshui River. Organic carbon and black carbon concentrations correlated well with those of total PCBs in the sediments, suggesting that both organic carbon and black carbon significantly affect the distribution of trace organic pollutants through either post-depositional adsorption, or by co-transport of similar source materials. The field results demonstrate that black carbon and plays an important role in the general distribution of PCBs, while concentrations of some specific PCBs are affected by both black carbon and organic carbon concentrations.     

Effect of humic substance on thermal treatment of chromium(VI)-containing latosol soil

Latosol soils contaminated with chromium(VI) [Cr(VI)], which is hazardous, can be recycled as raw materials for porcelain and construction sectors if a proper thermal stabilization process is implemented. This study investigates how thermal treatment affects Cr behavior during the sintering of latosol and deorganic latosol samples; both samples are artificially contaminated with CrO3. Approaches including X-ray absorption spectroscopy, scanning electron microscopy, N2-based Brunauer Emmett Teller surface analyzer, thermogravimetric analyzer/differential scanning calorimeter, and the toxicity characteristic leaching procedure promulgated by Taiwan Environmental Protection Administration are used in this study. After drying the Cr(VI)-contaminated latosol (i.e., containing 37,120 mg of Cr/kg sample) at 105 degrees C, approximately 80% of the doped CrO3 is chemically reduced to Cr(OH)3 by a humic substance naturally existing in the soil. In contrast, in the organics-free CrO3-contaminated latosol dried at 105 degrees C, only 9% of the doped CrO3 is reduced to Cr(OH)3. Heating the samples at 500 and 1100 degrees C transforms hazardous Cr(VI) into Cr(III) that is negligibly toxic; Cr2O3, which is insoluble, is detected as the most abundant Cr species. Moreover, formation of Cr2SiOs, which is suggested to relate to low Cr leaching, is only detected in the sample heated at 1100 degrees C. Surface morphology, surface area, and thermogravimetric analyzer/differential scanning calorimeter results demonstrate that thermal treatment at 1100 degrees C can incur considerable soil sintering/ melting if the humic substance in the soil has been heated off previously. Finally, Cr concentrations in the toxicity characteristic leaching procedure leachates collected from the samples thermally treated at 1100 degrees C for 4 hr are < or =0.21 mg of Cr L(-1) that are much less than the Taiwan Environmental Protection Administration regulatory limit (<5 mg of Cr L(-1)); consequently, these two samples are nonhazardous, and they have the potential for resource recycling. Conversely, Cr concentrations in the leachates from all 500 degrees C and 105 degrees C samples are in the 25.6-1279 mg L(-1) range.     

Isolated right diaphragmatic eventration mimicking congenital heart disease in utero

Diaphragmatic eventration is the upward displacement of the abdominal viscera secondary to a thin or paralytic diaphragm. Its clinical presentations and radiographic pictures are similar to those of diaphragmatic hernia. Prenatal diagnosis of diaphragmatic eventration is extremely rare. A pregnant woman was referred to us because of abnormal cardiac findings noted at 20 weeks of gestation. A diagnosis of partial anomalous pulmonary venous connection was made on the basis of our findings of right atrial enlargement with an abnormal vascular channel drainage to it. The infant was born via cesarean section at 40 weeks and developed complications of cyanosis immediately after birth. Postnatal imaging studies and surgical findings disclosed right side diaphragmatic eventration with liver and associated vasculature upward displacement into the right pleural cavity. The cardiac structure was otherwise normal. We conclude that when an abnormal vessel tracing and unexplainable cardiac chamber asymmetry is encountered, diaphragmatic eventration should be considered as one of the differential diagnoses. Correct recognition and transferral to the hospital for neonatal assistance may lead to timely and appropriate management of these fetuses. Copyright © 2005 John Wiley & Sons, Ltd.     

不同耕作方式下土壤氮素矿化和硝化特征研究

为探讨长期定位试验田不同耕作方式下土壤氮素矿化和硝化特征,采用室内恒温通气培养法,保持土壤田间持水量在65％条件下,测定不同耕作方式下表层土壤（0～20cm）在不同温度下的NH4^＋和NO3^-含量,并计算氮素矿化量和硝化率。结果表明,随着温度的升高,土壤氮素矿化和硝化作用均增强,几种耕作方式下土壤氮素矿化和硝化作用均表现为35℃〉30℃〉25℃。保护性耕作与水旱轮作和常规平作之间的矿化量存在显著的差异,垄作免耕〉厢作免耕〉水旱轮作〉常规平作。土壤氮素最终硝化率达到了60％～80％,表现为常规平作最高,水旱轮作次之,厢作免耕最低。矿化率与土壤有机质、碱解氮和速效磷对数均成显著正相关,相关系数分别为r^2=0．99,r^2=0．97,r^2=0．96,pH是影响硝化作用的重要因素,硝化率与土壤pH成显著正相关,r^2=0．991。     

库布齐沙漠自然植被与人工植被土壤水盐的空间异质性比较研究

干旱半干旱地区土壤水盐的空间分布对土地利用和生态恢复具有重要作用。运用传统统计学和地统计学对库布齐沙漠5种自然植被和5种人工植被0～10和10～20cm深度土壤水分和盐分的空间异质性进行了小尺度比较分析。结果表明：9种群落的土壤水盐平均值下层大于表层,且盐分的空间相关性较水分更高;人工植被土壤水分（CV=5.3%～22.7%）和盐分（CV=15.7%～51.2%）具有空间分布均匀、层间差异不明显等特征,而自然植被水分（CV=9.9%～32.6%）和盐分的（CV=26.9%～180.0%）却与之相反;小尺度上,人工植被土壤不同层间的水分关系、盐分关系以及水盐关系可能随建植时间的增加会越来越不明显,格局强度将不断减弱,这也极有可能改变大尺度上的水盐运移状况,进而影响研究区生态系统的稳定性和安全性。     

Effects of controller-pilot communication medium,flight phase and the role in the cockpit on pilots’ workload and situation awareness

This study explores the effects of communication medium, flight phase, and the role in the cockpit on pilots’ workload and situation awareness. Eight pilots with the experience of Controller-Pilot Data Link Communications (CPDLCs) participated in this simulated experiment. Two types of communication medium (voice and datalink), three types of flight phase (departure, cruise, and arrival), and two types of role (pilot flying and pilot non-flying) were investigated in the experiment. The results indicated that flight phase is a significant factor and cruise is the most suitable phase for datalink use on pilots’ acceptance, workload, and situation awareness performance. Both medium and role were not the significant factors. Since there is no significant difference on medium when no extra tasks and interferences involved in a normal flight, that the use of CPDLC can be justified during all phases of a no-event flight. In addition, the results of usability indicated that the simulated CPDLC with command selection functions proposed in this study provides good utility for the participants. In order to use the CPDLC for all phases of flight in the future, adding more command selection functions in place of typing messages by pilots and accommodating appropriate interfaces for different phases are recommended to enhance the usability of the CPDLC unit.     

Monitoring natural organic matter in water with scanning spectrophotometer

This study uses scanning ultraviolet-visible (UV-Vis) spectrophotometer to monitor natural organic matter (NOM) in water. The results showed that the area under the UV-Vis spectra is a good surrogate to monitor the concentration of the aqueous NOM. No apparent difference was found between the spectra of the three commercially available humic acids used in this study. The use of the scanning spectra compensates the potential random error in the absorbance determined at single wavelength due to the heterogeneous NOM compositions. The major interference of the proposed method comes from the formazine turbidity and nitrate nitrogen (NO3- -N). Although filtration with a 0.45-microm filter can remove most of the interference from formazine, some interference is still present at a wavelength less than 250 nm. Also it is found that the presence of the NO3- -N greatly affect the spectra of the NOM. In order to monitor the NOM in water with minimized interference, it is recommended that the area under the spectra between 250 and 350 nm should be used as a surrogate for concentration of NOM in water.