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211.
某冶炼厂拆迁场地土壤重金属污染健康风险评价 总被引:9,自引:5,他引:4
按照环保部最新颁布实施的污染场地风险评估技术导则(HJ 25.3—2014),选取Cu、Pb、Zn、Cd、Cr、As 6种重金属元素为主要污染物,结合Pearson相关分析及克里金差值法,对某冶炼厂拆迁场地土壤进行健康风险评价。结果表明:拆迁场地土壤中重金属污染集中于生产区及堆放场,污染程度为生产区≈堆放场生活区,6种重金属平均值低于《展览会用地土壤环境质量评价标准》B级(HJ 350—2007),Pb、Zn、Cd平均值高于广西省和中国土壤元素背景值;相关分析表明Cu分别与Pb、Zn、Cr、As,Pb-Cr、Pb-As及Zn-Cd存在极显著正相关关系;健康风险评价结果表明生活区土壤中6种重金属对人体健康不会产生不良或危害效应;生产区和堆放场土壤中Cr存在致癌风险,As存在致癌风险和非致癌危害。成人血铅模型(ALM)计算得出生活区、生产区及堆放场中成人血铅浓度值分别为4.98μg·d L-1、5.04μg·d L-1、5.03μg·d L-1,低于成人血铅浓度风险评价的基准值5.8μg·d L-1,且Pb的平均值低于国内外居住用地土壤铅环境基准值。 相似文献
212.
To increase the knowledge on the particulate matter of a wetland in Beijing, an experimental study on the concentration and composition of PM10 and PM2.5 was implemented in Beijing Olympic Forest Park from 2013 to 2014. This study analyzed the meteorological factors and deposition fluxes at different heights and in different periods in the wetlands. The results showed that the mean mass concentrations of PM10 and PM2.5 were the highest at 06:00–09:00 and the lowest at 15:00–18:00. And the annual concentration of PM10 and PM2.5 in the wetland followed the order of dry period (winter) > normal water period (spring and autumn) > wet period (summer), with the concentration in the dry period significantly higher than that in the normal water and wet periods. The chemical composition of PM2.5 in the wetlands included NH4+, K+, Na+, Mg2 +, SO42 −, NO3−, and Cl−, which respectively accounted for 12.7%, 1.0%, 0.8%, 0.7%, 46.6%, 33.2%, and 5.1% of the average annual composition. The concentration of PM10 and PM2.5 in the wetlands had a significant positive correlation with relative humidity, a negative correlation with wind speed, and an insignificant negative correlation with temperature and radiation. The daily average dry deposition amount of PM10 in the different periods followed the order of dry period > normal water period > wet period, and the daily average dry deposition amount of PM2.5 in the different periods was dry period > wet period > normal water period. 相似文献
213.
Cissy Ballen Mo Healey Mark Wilson Michael Tobler Mats Olsson 《Die Naturwissenschaften》2012,99(8):661-664
Telomeres shorten as a consequence of DNA replication, in particular in cells with low production of telomerase and perhaps in response to physiological stress from exposure to reactive oxygen species, such as superoxide. This process of telomere attrition is countered by innate antioxidation, such as via the production of superoxide dismutase. We studied the inheritance of telomere length in the Australian painted dragon lizard (Ctenophorus pictus) and the extent to which telomere length covaries with mass-corrected maternal reproductive investment, which reflects the level of circulating yolk precursor and antioxidant, vitellogenin. Our predictors of offspring telomere length explained 72?% of telomere variation (including interstitial telomeres if such are present). Maternal telomere length and reproductive investment were positively influencing offspring telomere length in our analyses, whereas flow cytometry-estimated superoxide level was negatively impacting offspring telomere length. We suggest that the effects of superoxide on hatchling telomere shortening may be partly balanced by transgenerational effects of vitellogenin antioxidation. 相似文献
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216.
三峡水库水位上升对香溪河流域典型滑坡的影响分析 总被引:5,自引:0,他引:5
在三峡水库蓄水后,香溪河流域众多滑坡出现变形失稳现象。白家堡滑坡、耿家坪滑坡、白马滩滑坡在蓄水后的变形特征各不相同。对库水位上升后3个滑坡的变形特征及其渗透性进行了比较研究,表明影响滑坡响应时间的主要因素是滑体的渗透性。以白家堡滑坡为例,利用摩根斯坦-普赖斯法,对不同c、值,进行75~175 m水位线的稳定性系数演算,发现各c、值不同水位线下稳定性系数曲线的变化规律有2种类型,即下降—平直型和下降—上升型,这种变化规律与浸水部位密切相关。 相似文献
217.
广州市PM10的时空变化特征分析 总被引:4,自引:0,他引:4
广州市的空气颗粒物污染呈逐年加重趋势,因此利用2001-2004年广州市空气自动监测点(国控点)监测的PM10日平均质量浓度资料,分析了广州市PM10的时空变化特征.统计结果表明,广州市PM10年平均质量浓度逐年递增,月平均质量浓度和季节变化趋势也较明显,秋冬季节污染较重,春夏季节污染较轻;污染较重的是海珠区和黄埔区,污染较轻的为越秀区、天河区和花都区;主成分分析显示各监测点对广州市PM10污染的贡献相当,不同监测点之间PM10质量浓度的变化主要受大尺度上的天气现象影响. 相似文献
218.
一体式膜-生物反应器中膜污染过程的动态分析 总被引:6,自引:1,他引:5
膜污染过程的动态研究对于有效地控制膜污染意义重大。结合膜过滤压差的上升和污染膜表面微观形态的变化 ,对不同污泥浓度和膜通量条件下 ,一体式膜 生物反应器中膜污染过程进行了动态分析。结果表明 ,膜污染初期主要是水中溶解性物质在膜表面附着 ,随后污泥在膜表面沉积。溶解性有机物在膜面的附着 ,对膜过滤压差即膜过滤阻力的变化影响不大 ,而活性污泥在膜表面的大量沉积将导致膜过滤压差迅速上升。污泥浓度愈高 ,膜通量愈大时 ,活性污泥颗粒愈易在膜面沉积。通过停止进出水维持空曝气、降低反应器内污泥浓度或延长膜的停抽时间可以使沉积在膜表面的悬浮污泥脱离膜表面 ,从而使膜过滤能力得到很好的恢复。采用经典的膜污染模型对各运行阶段膜污染模式进行了分析 ,模型拟合结果与电镜观察结果基本吻合。 相似文献
219.
In this study, we examined how and when transformational leadership affected team knowledge exchange. Taking a goal pursuit perspective, we hypothesized two parallel mediating mechanisms—team knowledge goal generation and team knowledge goal striving—linking transformational leadership to team knowledge exchange. In addition, we investigated whether team-level team-member exchange served as a boundary condition that qualified the effects of transformational leadership on team knowledge goal generation and striving. We tested our hypotheses using time-lagged data from 118 work teams of a large Chinese manufacturing firm. Our findings provided support for the proposed parallel mediating mechanisms (i.e., team knowledge goal generation and team knowledge goal striving) that linked transformational leadership to team knowledge exchange. In addition, we found that team-level team-member exchange could strengthen the positive effect of transformational leadership on team knowledge exchange via team knowledge goal generation. By taking the novel lens of team goal pursuit, this study contributes to the literature on leadership and teams by shedding light on how transformational leadership triggers the goal pursuit process of team knowledge exchange. 相似文献
220.