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141.
When investigating the impact of air pollution on health, particulate matter less than 2.5 μm in aerodynamic diameter(PM_(2.5)) is considered more harmful than particulates of other sizes. Therefore, studies of PM_(2.5) have attracted more attention. Beijing, the capital of China,is notorious for its serious air pollution problem, an issue which has been of great concern to the residents, government, and related institutes for decades. However, in China,significantly less time has been devoted to observing PM_(2.5) than for PM_(10). Especially before 2013, the density of the PM_(2.5) ground observation network was relatively low, and the distribution of observation stations was uneven. One solution is to estimate PM_(2.5) concentrations from the existing data on PM_(10). In the present study, by analyzing the relationship between the concentrations of PM_(2.5) and PM_(10), and the meteorological conditions for each season in Beijing from 2008 to 2014, a U-shaped relationship was found between the daily maximum wind speed and the daily PM concentration, including both PM_(2.5) and PM_(10). That is, the relationship between wind speed and PM concentration is not a simple positive or negative correlation in these wind directions; their relationship has a complex effect, with higher PM at low and high wind than for moderate winds.Additionally, in contrast to previous studies, we found that the PM_(2.5)/PM_(10) ratio is proportional to the mean relative humidity(MRH). According to this relationship, for each season we established a multiple nonlinear regression(MNLR) model to estimate the PM_(2.5) concentrations of the missing periods. 相似文献
142.
Andrew O. Hughes Jon M. Olley Jacky C. Croke Ian T. Webster 《Journal of environmental radioactivity》2009,100(10):858-865
Fallout 137Cs has been widely used to determine floodplain sedimentation rates in temperate environments, particularly in the northern hemisphere. Its application in low fallout, tropical environments in the southern hemisphere has been limited. In this study we assess the utility of 137Cs for determining rates of floodplain sedimentation in a dry-tropical catchment in central Queensland, Australia. Floodplain and reference site cores were analysed in two centimetre increments, depth profiles were produced and total 137Cs inventories calculated from the detailed profile data. Information on the rates of 137Cs migration through local soils was obtained from the reference site soil cores. This data was used in an advection–diffusion model to account of 137Cs mobility in floodplain sediment cores. This allowed sedimentation rates to be determined without the first year of detection for 137Cs being known and without having to assume that 137Cs remains immobile following deposition. Caesium-137 depth profiles in this environment are demonstrated to be an effective way of determining floodplain sedimentation rates. The total 137Cs inventory approach was found to be less successful, with only one of the three sites analysed being in unequivocal agreement with the depth profile results. The input of sediment from catchment sources that have little, or no, 137Cs attached results in true depositional sites having total inventories that are not significantly different from those of undisturbed reference sites. 相似文献
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144.
研究了大丰风电场一期、二期工程对盐城沿海湿地珍禽国家级自然保护区的生态影响.结果表明,在自然保护区实验区内建风电场会改变自然保护区生态结构和功能,使生物量减少,鸟类栖息地丧失,物种多样性下降,景观破碎化.提出了对策措施,以降低由于风电场的建设对自然保护区造成的生态影响. 相似文献
145.
稀有鮈鲫神经发育相关基因的克隆、同源性分析及组织分布 总被引:1,自引:0,他引:1
作为重要的本土模式鱼类,稀有鮈鲫神经发育相关的生物学背景几乎空白,导致其在神经毒性评价方面的应用受到限制。本文从稀有鮈鲫脑部克隆得到了神经发育相关的神经生长因子(nerve growth factor;ngf)、脑源性神经营养因子(brain-derived neurotrophic factor;bdnf)、胶质纤维酸性蛋白(glial fibrillary acidic protein;gfap)、髓鞘相关糖蛋白(myelin-associated glycoprotein;mag)、P0蛋白(myelin protein zero;mpz)、微管蛋白α1(α1-tubulin)和Y染色体性别决定基因10(SRY-box containing gene 10;sox10)等基因的片段,并对其进化树及表达谱进行了分析。序列分析表明,bdnf的核苷酸序列与鲫鱼、鲤鱼的同源性最高,均为98%;gfap、ngf、mag和α1-tubulin与斑马鱼的同源性最高,分别为95%、92%、92%和96%;mpz与黑头软口鲦的同源性最高,为94%;sox10与鳙鱼同源性最高,达97%。表达谱分析结果表明,ngf、bdnf、mag、mpz、α1-tubulin和sox10基因均在脑组织中表达量最高,gfap在脊髓中表达量最高,上述结果为这一模式鱼类在神经发育学和神经毒性效应评价方面的应用奠定了基础。 相似文献
146.
Ying Han Huiting Xie Wenbin Liu Haifeng Li Mengjing Wang Xuebin Chen Xiao Liao Nan Yan 《Frontiers of Environmental Science & Engineering》2016,10(6):7
We assessed the contamination levels of Mn, Zn, Cr, Cu, Ni, Pb, As and Hg and the risks posed by these potentially harmful elements in top-soils around a municipal solid waste incinerator (MSWI).We collected 20 soil samples, with an average pH of 8.1, and another fly ash sample emitted from the MSWI to investigate the concentrations of these elements in soils. We determined the concentrations of these elements by inductively coupled plasma–optical emission spectrometer (ICP-OES), except for Hg, which we measured by AF-610B atomic fluorescence spectrometer (AFS). We assessed the risks of these elements through the use of geoaccumulation index (I geo), potential ecological risk index (RI), hazard quotient (HQ i ) and cancer risk (Risk i ). The results showed that concentrations of potentially harmful elements in soil were influenced by the wind direction, and the concentrations of most elements were higher in the area northwest of the MSWI, compared with the area southeast of the incinerator, with the exception of As; these results were in accordance with those results acquired from our contour maps. According to the I geo values, some soil samples were clearly polluted by Hg emissions. However, the health risk assessment indicated that the concentrations of Hg and other elements in soil did not pose non-carcinogenic risks to the local populations. This was also the case for the carcinogenic risks posed by As, Cr, and Ni. The carcinogenic risk posed by As was higher, in the range 6.49 × 10–6–9.58 × 10–6, but this was still considered to be an acceptable level of risk. 相似文献
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148.
典型电器工业区河涌沉积物中的多溴联苯醚空间和垂直分布 总被引:4,自引:4,他引:4
对珠江三角洲佛山市顺德区容桂镇电器工业区河涌沉积物多溴联苯醚(PBDEs)的含量进行了空间和垂直分布研究.选择该镇中心城区内河涌作为研究河道,根据河涌水流情况选取8个采样点采集沉积物样品.所有样品中均检出PBDEs.各监测点的PBDEs总含量变化范围为62~349 ng.g-1(平均为178 ng.g-1),各采样点的浓度差异较大.其中,十溴联苯醚含量为56~337 ng.g-1(平均为171 ng.g-1),占PBDEs总含量的90%~99%(平均95%).所检测到的部分同系物(如BDE-196、197和203)可能是BDE-209的降解产物.PBDEs的垂直分布模式显示,0~10 cm层面样品的PBDEs浓度为147 ng.g-1,30~40 cm层面样品的PBDEs浓度为260 ng.g-1,PBDEs在沉积物中的丰度随垂直深度的增加而增加.12种同系物在采自各个深度层样品中的比例基本相同,由十溴工业品来源的BDE-209、208、207和206占总PBDEs的94%,而五溴和八溴所占比例较低.由此可见,该地区普遍存在PBDEs污染,其中十溴联苯醚是最主要污染物,这可能与十溴工业品是电器工业主要使用的阻燃材料相关. 相似文献
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150.
作为传统的黄沙监测技术的发展和延伸,激光雷达已经成为一种全新的黄沙观测手段,它的使用标志着对黄沙的观测由二维空间发展到三维空间。本文简要阐述了NIES型激光雷达的工作原理,激光雷达的构成,对利用激光雷达观测黄沙气溶胶进行了讨论,提出了利用激光雷达观测黄沙天气,具有连续性、准确性和可视化的三大特点。 相似文献