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221.
青藏高原内陆典型冰川区"冰川-径流"汞传输过程 总被引:3,自引:0,他引:3
为研究青藏高原内陆典型冰川区"冰川-径流"汞输送过程,于2011年8月15日~9月9日对青藏高原内陆念青唐古拉山脉扎当冰川-曲嘎切流域内雪坑、冰川融水以及径流进行了采样,检测了不同环境介质中汞浓度,并分析了不同介质中汞的控制因素及输送过程.结果表明,扎当冰川-曲嘎切流域内雪坑、冰川融水以及曲嘎切径流中总汞浓度分别为(3.79±5.12)、(1.06±0.77)和(1.02±0.24)ng·L-1,处于全球背景水平.不同环境介质中均以颗粒态汞为主,受到总悬浮颗粒物和径流量的控制.随着气温升高,冰川消融,受其补给的河流径流量增加.不同环境介质间,从冰川末端融水到曲嘎切下游河水,总汞浓度峰值时间分别是14:00、16:00和20:00以后,体现了汞在"冰川-径流"环境系统中随冰川消融、径流量变化的释放和传输过程.冰川补给河流汞的传输受多种因素制约,气候变化背景下,冰川消融和径流增加带来的侵蚀将在汞释放及其向下游传输发挥日益重要的作用. 相似文献
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223.
Lee SM Lee JW Park KR Hong EJ Jeung EB Kim MK Kang HY Choi IG 《Journal of environmental science and health. Part. B》2006,41(4):385-397
The white rot fungus Stereum hirsutum was used to degrade methoxychlor [2,2,2-trichloro-1,1-bis(4-methoxyphenyl)ethane] in culture and the degraded products were extensively determined. The estrogenic activity of the degraded products of methoxychlor was examined using cell proliferation and pS2 gene expression assays in MCF-7 cells. S. hirsutum showed high resistance to methoxychlor 100 ppm, and the mycelial growth was fully completed within 8 days of incubation at 30 degrees C. Methoxychlor in liquid culture medium was gradually converted into 2,2-dichloro-1,1-bis(4-methoxyphenyl)ethane, 2,2-dichloro-1,1-bis(4-methoxyphenyl)ethylene, 2-chloro-1,1-bis(4-methoxyphenyl) ethane, 2-chloro-1,1-bis(4-methoxyphenyl) ethylene, and 1,1-bis(4-methoxyphenyl)ethylene, indicating that methoxychlor is dominantly degraded by dechlorination and dehydrogenation. MCF-7 cells were demonstrated to proliferate actively at the 10-5 M concentration of methoxychlor. However, cell proliferation was significantly inhibited by the incubation with methoxychlor culture media containing S. hirsutum. In addition, the expression level of pS2 mRNA was increased at the concentration (10-5 M) of methoxychlor. The reductive effect of S. hirsutum for methoxychlor was clear but not significant as in the proliferation assay. 相似文献
224.
Andrew Carlin Caroline Kadji Mieke M. Cannie Serena Resta Xin Kang Jacques C. Jani 《黑龙江环境通报》2020,40(1):125-135
Extremes of fetal growth can increase adverse pregnancy outcomes, and this is equally applicable to single and multiple gestations. Traditionally, these cases have been identified using simple two-dimensional ultrasound which is quite limited by its low precision. Magnetic resonance imaging (MRI) has now been used for many years in obstetrics, mainly as an adjunct to ultrasound for congenital abnormalities and increasingly as part of the post-mortem examination. However, MRI can also be used to accurately assess fetal weight as first demonstrated by Baker et al in 1994, using body volumes rather than standard biometric measurements. This publication was followed by several others, all of which confirmed the superiority of MRI; however, despite this initial promise, the technique has never been successfully integrated into clinical practice. In this review, we provide an overview of the literature, detail the various techniques and formulas currently available, discuss the applicability to specific high-risk groups and present our vision for the future of MRI within clinical obstetrics. 相似文献
225.
城市化造成我国城乡教育资源分布与实际需求存在偏差:农村小学教育资源浪费,城镇小学不能满足学龄儿童入学需求,城镇中学升学率的提高越来越受到教学资源不足的限制。在研究快速城市化背景下我国城乡基础教育资源优化配置问题的基础上。就农村基础教育资源的优化配置,提出有效盘活存量资源、合理配置增量资源、加强基础教育、发展职业技术教育、开展农业技术培训、强化农村人口思想素质教育的对策建议。就城镇基础教育资源的优化配置,提出扩大名校办学规模、加大对非“重点”学校的投入力度、发挥市场在教育资源配置中的作用的对策建议。 相似文献
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227.
Sun Shiwei Kang Shichang Huang Jie Chen Shengyun Zhang Qianggong Guo Junming Liu Wenjie Neupane Bigyan Qin Dahe 《Environmental science and pollution research international》2017,24(17):15078-15088
Environmental Science and Pollution Research - The Tibetan Plateau (TP) is home to the largest permafrost bodies at low- and mid-latitudes, yet little is known about the distribution and variation... 相似文献
228.
模糊综合法在城市绿地系统景观生态综合评价中的应用——以上海市为例 总被引:9,自引:0,他引:9
绿地是城市人工景观中最重要的自然要素,以往对绿地景观生态的研究主要集中在能量流动和空间结构等方面,很少涉及城市绿地景观生态的综合评价。本文利用融模糊综合评判和模糊聚类分析于一体的模糊综合法对城市绿地系统景观生态进行了综合评价。 相似文献
229.
The useful life of consumer electronic devices is relatively short, and decreasing as a result of rapid changes in equipment features and capabilities. This creates a large waste stream of obsolete electronic equipment, electronic waste (e-waste).Even though there are conventional disposal methods for e-waste, these methods have disadvantages from both the economic and environmental viewpoints. As a result, new e-waste management options need to be considered, for example, recycling. But electronic recycling has a short history, so there is not yet a solid infrastructure in place.In this paper, the first half describes trends in the amount of e-waste, existing recycling programs, and collection methods. The second half describes various methods available to recover materials from e-waste. In particular, various recycling technologies for the glass, plastics, and metals found in e-waste are discussed. For glass, glass-to-glass recycling and glass-to-lead recycling technologies are presented. For plastics, chemical (feedstock) recycling, mechanical recycling, and thermal recycling methods are analyzed. Recovery processes for copper, lead, and precious metals such as silver, gold, platinum, and palladium are reviewed. These processes are described and compared on the basis of available technologies, resources, and material input–output systems. 相似文献
230.
Airborne particulate matter (PM) concentrations were measured in Iksan, a suburban area in South Korea during April, 2003.
PM2.5 (particles with an aerodynamic diameter less than 2.5 μm) and PM10 (particles with an aerodynamic diameter less than 10 μm) samples were collected, and the chemical characteristics of particles
were examined for diurnal patterns, yellow dust/rainfall influences, and scavenging effects. Average concentrations of PM2.5 and PM10 mass measured were 37.3 ± 16.2 μg m−3 and 60.8 ± 29.5 μg m−3, respectively. The sum of ionic chemical species concentrations for PM2.5 and PM10 was 16.9 ± 7.3 and 23.1 ± 10.1 μg/m3, respectively. A significant reduction in PM mass concentrations during rainfall days was observed for coarse mode (PM2.5 − 10) particles, but less reduction was found for fine (PM2.5) mass concentration. SO4
2−, NH4
+, and K+ predominated in fine particulate mode, NO3
− and Cl− predominated in fine particle mode and coarse particle mode, but Na+, Mg2+, and Ca2+ mostly existed in coarse mode. The high concentration of ammonium due to local emissions and long-range transport neutralized
sulfate and nitrate to ammonium sulfate and ammonium nitrate, which were major forms of airborne PM in Iksan. Average mass
concentrations of PM10 in daytime and at night were 57.6 and 70.0 μg m−3, and those of PM2.5 were 35.4 and 42.5 μg m−3, respectively. NO3
− and Cl− in both PM2.5 and PM10 were about double at night than in the daytime, while the rest of the chemical species were equal or a little higher at night
than in the daytime. The results suggest the formation of ammonium nitrate and chloride when high ammonia concentration and
low air temperature are allowed. Backward air trajectory analyses showed that air masses arriving at the site during yellow
dust period were transported from arid Chinese regions, which resulted in high concentrations of airborne PM mass concentrations.
In the meantime, air mass trajectories during a rainfall period were mostly from the Pacific Ocean or the East China Sea,
along with a relatively low PM concentration. 相似文献