Bed sediment-associated trace metals in an urban stream, Oahu, Hawaii   总被引：78，自引：0，他引：78  

R. A. Sutherland 《Environmental Geology》2000,39(6):611-627

 Of the 117 stream and lake systems sampled nationwide, fish from Manoa Stream on Oahu, Hawaii, have consistently shown the highest Pb concentrations. Therefore a detailed study was conducted to examine total metal contents in bed sediments from a 5.8-km stretch of Manoa Stream. A total of 123 samples (<63 μm) were examined for 18 elements and 14 samples for 21 elements. Selected samples were also examined using different leach solutions to examine metal phase associations. All trace metal data, computations of enrichment ratios and the modified index of geoaccumulation point to mineralogical control for Cr and Ni; minor anthropogenic contamination for Ba, Cd, Cu, Hg and Zn; and a very strong contamination signal for Pb. Maximum Pb contents (up to 1080 mg kg⁻¹) were associated with anthropogenic material dumping in minor tributaries, storm sewer sediments and sediments in the “lower” section of the basin. Proportionally Pb had the highest non-residual component of elements examined; dominantly in the reducible phase associated with Mn and amorphous Fe oxyhydroxides. The contamination signal was typically lowest in the “undisturbed” headwater reach of the basin (above 5.1 km) with significant increases throughout the “residential” and “commercial-institutional” zones of the mid-basin. The spatial pattern of bed sediment contamination and evidence from storm sewer-outlet sediments strongly indicates that Pb, and to a lesser degree some other metals, is still being transported to the stream and the primary agent is soil erosion and transport of metals sorbed to sediments. The primary source of sediment-associated metals is considered to be the automobile, though other minor sources can not be ruled out. Received: 3 November 1998 · Accepted: 26 January 1999  相似文献   

改性当地土壤技术修复富营养化水体的综合效果研究:Ⅲ.模拟湖泛水体的应急治理效果   总被引：1，自引：0，他引：1  

代立春  潘纲  李梁  李宏  毕磊  尚媛媛  王丽静  王丹  张洪刚  李巧霞  古小治  钟继承 《湖泊科学》2013,25(3):342-346

为了探索原位解决湖泛引起的水体感官和水质恶化问题,本研究在室内考察了改性当地土壤对湖泛黑物质的絮凝去除效果及土壤和沙子覆盖对絮体再悬浮的抑制作用,并在梅梁湾围隔实验中考察了改性当地土壤湖泊综合修复技术对模拟湖泛水体嗅味物质和营养盐的去除及水体溶解氧(DO)的改善效果.室内研究结果表明,壳聚糖改性土壤对湖泛水体黑物质的絮凝去除效果比聚合氯化铝更佳,在55 mg/L的壳聚糖改性土壤投加量时,水体浊度从对照的 >2000NTU降低到5 NTU,土壤和沙子覆盖能够有效地减少湖泛水体黑物质絮凝去除后的再悬浮.现场研究结果表明,该技术处理30 min后总氮和总磷的去除率达到97.0%,嗅味物质DMTS和MIB的去除率达到75.0%以上,水体表层DO增加了75.0%,底层DO增加了183.5%.改性当地土壤湖泊综合修复技术对湖泛水体的感官和水质起到明显的应急改善效果.  相似文献   

河北尚义M4.0地震加速度记录时频特性分析     

吕国军  张合  李皓  李姜  李胜强 《地震地磁观测与研究》2018,39(6):136-142

2016年6月23日,河北张家口尚义县发生M 4.0地震,发震构造为尚义-平泉断裂。采用基于聚类经验模态分解（EEMD）的HHT计算方法,对尚义M4.0地震强震动记录进行EEMD分解、Hilbert谱变换及谱分析,得到强震动台站的加速度记录分量的时程、FFT谱和边际谱、瞬时能量谱及时频谱,对比分析并认识各种谱的时频特性及规律,做好灾前预防工作,以减少人民生命财产损失。  相似文献   

Numerical exploration of the motion of variable mass test particle on the perturbed circular restricted three-body configuration     

《New Astronomy》2022

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