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21.
Gascó C Antón MP Pozuelo M Clemente L Rodríguez A Yañez C González A Meral J 《Journal of environmental radioactivity》2006,89(2):159-171
Within an extensive multinational and multidisciplinary project carried out in Do?ana National Park (Spain) to investigate its preservation and regeneration, the filling velocity of the salt marshes has been evaluated through the calculation of their average sediment accumulation rates. (239+240)Pu and (137)Cs from weapons testing fallout and total (210)Pb distribution profiles and inventories have been determined in some of the most characteristic zones of the park, namely, the ponds (or "lucios") and the waterjets (or "ca?os"). Plutonium inventories range from 16 to 101 Bq m(-2), (137)Cs values fluctuate between 514 and 3,758 Bq m(-2) and unsupported (210)Pb values comprise between 124 and 9398 Bq m(-2). Average sedimentation rates range from 3 to 5 mm y(-1) (1952-2002). These data are higher than those obtained by carbon dating for the period 6,500 AD-present, estimated as 1.5-2 mm y(-1), suggesting an increase in the accumulation of sediments and the alteration of the park's hydrodynamics caused by the re-channeling of the major rivers feeding the salt marshes. 相似文献
22.
A 52-day continuous semi-static waterborne exposure (test media renewed daily) regimen was employed to investigate the accumulation and elimination profiles of two iron oxide nanomaterials (nano-Fe2O3 and nano-Fe3O4) in zebrafish (Danio rerio). Adult zebrafish were exposed to nanomaterial suspensions with initial concentrations of 4.0 and 10.0 mg/L for 28 days and then were moved to clean water for 24 days to perform the elimination experiment. Fe content was measured in fish body and feces to provide data on accumulation and elimination of the two iron oxide nanomaterials in zebrafish. The experiment revealed that: (1) high accumulation of nano-Fe2O3 and nano-Fe3O4 were found in zebrafish, with maximum Fe contents, respectively, of 1.32 and 1.25 mg/g for 4.0 mg/L treatment groups and 1.15 and 0.90 mg/g for 10.0 mg/L treatment groups; (2) accumulated nanoparticles in zebrafish can be eliminated efficiently (the decrease of body burden of Fe conforms to a first-order decay equation) when fish were moved to nanoparticle-free water, and the elimination rates ranged from 86% to 100% by 24 days post-exposure; and (3) according to analysis of Fe content in fish excrement in the elimination phase, iron oxide nanomaterials may be adsorbed via the gastrointestinal tract, and stored for more than 12 days. 相似文献
23.
化工过程中毒事故风险的模糊综合评估 总被引:2,自引:2,他引:2
影响化工过程中毒事故风险性的不确定因素较多,其风险具有相对性且大部分因素具有模糊性的特点。为此,笔者建立了化工过程多级多指标中毒事故风险评估指标体系,根据模糊优选理论,提出了中毒事故风险的模糊综合评估模型,运用模糊层次分析法确定各指标权重,结合有关统计数据及工厂实际,对化工过程潜在的中毒事故风险性进行模糊综合评估,所获结果为化工过程中毒事故的综合防治提供了理论依据 相似文献
24.
Accumulation of Hg(II) by microbial biofilms on suspended particulate matter 相似文献
25.
Mechanism of sulfur capture during coal briquette combustion 总被引:2,自引:0,他引:2
1IntroductionChinaisacountryinwhichcoalisusedasthemainenergysource.Theproportionofcoalwilbeabout75%attheendofthiscentury,andh... 相似文献
26.
为了对冶金企业高温熔融金属作业人员的可靠性进行评估和量化,基于认知可靠性与失误分析方法(CREAM),提出了适用于高温熔融金属作业的人员可靠性分析方法。该方法给出了通用效能条件(Common Performance Condition, CPC)的评估细则,采用层次分析法(Analytic Hierarchy Process,AHP)与熵值法相结合的CPC因子权重确定方法,利用模糊数学原理实现CPC因子输入的模糊化,从而计算高温熔融金属作业人员失误概率(HEP)和可靠度。通过对炼钢冶炼作业的人员可靠性分析的结果表明:该方法合理有效,具有一定的应用性。 相似文献
27.
主要分析了化学实验室产生的环境污染特点,指出化学实验室是一类典型的、严重的小型污染源.在此基础上提出了防治化学实验室污染、加强实验室环境管理的方法和措施. 相似文献
28.
Holographic quantitative structure-activity relationship(HQSAR) is an emerging QSAR technique with the combined application of molecular hologram, which encoded the frequency of occurrence of various molecular fragment types, and the subsequent partial least squares(PLS) regression analysis. In this paper, the acute toxicity data to the guppy( poecilia reticulata) for a series of 56 substituted benzenes, phenols, aromatic amines and nitro-aromatics were subjected and this resulted in a model with a high predictive ability. The influence of fragment size and fragment distinction parameters on the quality of HQSAR model was investigated. The robustness and predictive ability of the model were also validated by leave-one-out (LOO) cross-validation procedure and external testing data set. 相似文献
29.
Xiaohui Wang Shuai Du Tao Ya Zhiqiang Shen Jing Dong Xiaobiao Zhu 《Frontiers of Environmental Science & Engineering》2019,13(1):14
30.
As an efficient method for ammonium (NH4+) removal, contact catalytic oxidation technology has drawn much attention recently, due to its good low temperature resistance and short start-up period. Two identical filters were employed to compare the process for ammonium removal during the start-up period for ammonium removal in groundwater (Filter-N) and surface water (Filter-S) treatment. Two types of source water (groundwater and surface water) were used as the feed waters for the filtration trials. Although the same initiating method was used, Filter-N exhibited much better ammonium removal performance than Filter-S. The differences in catalytic activity among these two filters were probed using X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and compositional analysis. XRD results indicated that different manganese oxide species were formed in Filter-N and Filter-S. Furthermore, the Mn3p XPS spectra taken on the surface of the filter films revealed that the average manganese valence of the inactive manganese oxide film collected from Filter-S (FS-MnOx) was higher than in the film collected from Filter-N (FN-MnOx). Mn(IV) was identified as the predominant oxidation state in FS-MnOx and Mn(III) was identified as the predominant oxidation state in FN-MnOx. The results of compositional analyses suggested that polyaluminum ferric chloride (PAFC) used during the surface water treatment was an important factor in the mineralogy and reactivity of MnOx. This study provides the theoretical basis for promoting the wide application of the technology and has great practical significance. 相似文献