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521.
Robin D. Calfee Edward E. Little Laverne Cleveland Mace G. Barron 《Environmental science and pollution research international》1999,6(4):207-212
Traditionally, the toxic effects of petroleum have been investigated by conducting studies in the absence of ultraviolet radiation
(UV). Photomediated toxicity is often not considered, and the toxic effects of an oil spill can be grossly underestimated.
The toxicity of a weathered oil collected from a monitoring well at an abandoned oil field toCeriodaphnia dubia was examined in the presence of UV. A solar simulator equipped with UVB, UVA, and cool white lamps was used to generate environmentally
comparable solar radiation intensities.C. dubia were exposed to six concentrations of water accommodated fractions (WAF) of weathered oil in conjunction with three levels
of laboratory simulated UV (Reference = < 0.002 μW/cm2UVB; 3.0 μW/cm2 UVA; Low = 0.30 μW/cm2 UVB; 75.0 μW/cm2 UVA; High = 2.0 μW/cm2 UVB; 340.0 μW/cm2 UVA) and visible light. Seven day static renewal bioassays were used to characterize WAF/UV toxicity. WAF toxicity significantly
(p < 0.05) increased when the organisms were exposed to WAF in the presence of UV. The photoenhanced toxicity of the WAF increased
with WAF concentration within each UV regime. Relative to the reference light regime, the average number of neonates from
adults exposed to 1.6 mg TPH/L decreased significantly by 20% within the low light regime, and by 60% within the high light
regime. These results indicate that organisms exposed to dissolved-phase weathered oil in the presence of environmentally
realistic solar radiation, exhibit 1.3–2.5 times greater sensitivity, relative to organisms exposed under traditional laboratory
fluorescent lighting. 相似文献
522.
David L. Fabacher Edward E. Little Gary K. Ostrander 《Environmental science and pollution research international》1999,6(2):69-71
We exposed albino and pigmented medakaOryzias latipes to simulated solar ultraviolet-B (UVB) radiation to determine if albino medaka were less tolerant of UVB radiation than medaka
pigmented with melanin. There was no difference in the number of albino and pigmented medaka that died during the exposure
period. Spectrophotometric analyses of the outer dorsal skin layers from albino and pigmented medaka indicated that, prior
to exposure, both groups of fish had similar amounts of an apparent colorless non-melanin photoprotective substance that appears
to protect other fish species from UVB radiation. Our results indicate that albino medaka were as tolerant of UVB radiation
as pigmented medaka because they had similar amounts of this photoprotective substance in the outer layers of the skin. 相似文献
523.
双流机场全年近1/3的日子有低见度天气出现,最多的冬季平均日数达到的总数的80%,而且低能见度有明显的季节变化和日变化。低能见度主要由辐射雾造成。二次低能见度天气为其特点,主是由弱冷空气进入暖湿气团所致。 相似文献
524.
龚建华 《应用与环境生物学报》2001,7(5):478-482
为研究电磁辐射场对微生物细胞的“非热效应”,选用几株工业微生物(产L-精氨酸钝齿棒状杆菌A6,产L-赖氨酸钝齿棒状杆菌LB6和产胞内SOD酶酵母菌S1)进行了初步探讨,试验结果表明,置于2μm-1mm频段电磁场接受辐射处理后的试验样本细胞对热的承受能力提高,表现为在较高温度下细胞生长速度的增加,处于对数生长期的细胞对辐射刺激有更明显的敏感反应,较低pH可以一定程度地强化辐射处理的效果,试验结果还进一步证明了以上效应产生于电磁辐射场的“非热效应”,而不是简单的热效应或微生物的自发突变。 相似文献
525.
526.
对自行研制的电子设备太阳辐射试验系统进行了介绍。设备研制中对试验系统的辐照灯阵进行了优化设计,同时根据环境试验要求,介绍了太阳辐射试验设备研制过程中所遇到的辐射光源选择及强度控制、光谱分布修正和光源启动系统等技术难点,并给出了解决途径。该试验系统研制成功,为考核装备的环境适应性和产品可靠性提供了科学的试验手段。 相似文献
527.
This study is aimed to clarify whether effect of low-level microwave radiation on human brain differs at different modulation
frequencies. Resting EEG recordings were done on different groups of healthy volunteers. The 450 MHz microwave radiation modulated
at 40 and 70 Hz (15 subjects) and 217 and 1,000 Hz (19 subjects) frequencies was applied. The results of our previous study
at 7, 14 and 21 Hz modulation were included into analysis. Ten cycles of the exposure (1 min off and 1 min on) at each fixed
modulation frequencies were applied. The field power density at the scalp was always 0.16 mW/cm2. Our results showed that microwave exposure increased the EEG energy at EEG frequencies lower or close to the modulation
frequency. No effect was detected at EEG frequencies higher than the modulation frequency. Statistically significant changes
were caused by exposure in the EEG alpha and beta frequency bands; no significant effect was detected in the theta band. Our
results suggest that telecommunication devices with complex spectrum of modulation frequencies like mobile phone can affect
all human EEG frequency bands. 相似文献
528.
In this study, an in situ microwave activated platinum electrode was developed for the first time to completely incinerate the azo dye simulated wastewater containing methyl orange. The experiments were carried out in a circulating system under atmospheric pressure. Azo bond of methyl orange was partly broken on Pt, certain decoloration was reached, and the total organic carbon was not removed effectively without microwave activation. However, methyl orange was mineralized completely and efficiently on the in situ microwave activated Pt. 2,5-Dinitrophenol, p-nitrophenol, hydroquinone, benzoquinone, maleic and oxalic acids are the main intermediates during degradation of methyl orange. Aromatic products are the main substances leading to the poisoning of Pt and decrease of electrochemical oxidation efficiency, so methyl orange removal can not be carried out thoroughly. However, the intermediates were broke down quickly with in situ microwave activation promoting the mineralization of methyl orange on Pt. 相似文献
529.
The present work describes a model for predicting the population dynamics of the main components (resources and consumers) of terrestrial ecosystems exposed to ionising radiation. The ecosystem is modelled by the Lotka–Volterra equations with consumer competition. Linear dose–response relationships without threshold are assumed to relate the values of the model parameters to the dose rates. The model accounts for the migration of consumers from areas characterised by different levels of radionuclide contamination. The criteria to select the model parameter values are motivated by accounting for the results of the empirical studies of past decades. Examples of predictions for long-term chronic exposure are reported and discussed. 相似文献
530.
In case of an accidental release of radioactive substances into the environment, it is important to quickly and reliably estimate the radiation dose received by people in the affected area, and to determine the extent of the contamination. Measurements of the extent of the release and the subsequent contamination can be facilitated if there are predetermined reference sampling sites with known background radiation and inventory of radionuclides. Since 1996, 34 reference sites for soil sampling, field gamma, and intensimeter measurements have been established in western Sweden. Time series data for dose rates and radioisotope inventory have been collected at these sites, allowing for the investigation of changes in these parameters over time. The mass activity densities for the uranium and thorium series elements varied approximately between 10 and 50 Bq/kg and between 10 and 40 Bq/kg, respectively. The mass activity density of 40K was approximately in the range 300–800 Bq/kg. The radiation exposure due to 137Cs was rather small in this area. The dose rates calculated from in situ measurement data showed that the contribution to the total dose rate was almost entirely due to naturally occurring radionuclides. The measured dose rate was about twice as high as the calculated rate, even after subtracting the contribution from cosmic radiation. This may be explained by the fact that intensimeters generally are calibrated to measure the quantity ambient dose equivalent, which should not underestimate the effective dose. 相似文献