煤矸石中金属元素对人体健康影响的研究

矿业活动是环境中金属元素的主要来源,而煤矸石是我国矿业固体废料中产生量、累计积存量和占地面积最大的固体废物,它含有铁、钠、锌、铜、锰等22种有害微量元素。分析煤矸石中这些金属元素在环境中的迁移转化途径及其对生物体的毒性效应,对人体健康影响的研究具有重要意义。本文详细阐述了金属元素对生物体(植物和人)的生物效应,重点分析了煤矸石中几种常见的金属元素在环境中的迁移途径及它们对人体健康的影响和毒性效应,并提出了防治煤矸石环境污染的相应对策。     

可视电话电磁兼容案例分析

通过对可视电话认证测试中静电放电和辐射骚扰试验问题对策的分析,探讨在测试过程中如何分析电磁兼容问题的三要素并依据这三个要素进行改进,最终通过认证测试,并总结了电信终端设备电磁兼容认证测试中有关问题的分析方法.     

The effects of land use on fluvial sediment chemistry for the conterminous U.S. - results from the first cycle of the NAWQA Program: trace and major elements, phosphorus, carbon, and sulfur

In 1991, the U.S. Geological Survey (USGS) began the first cycle of its National Water Quality Assessment (NAWQA) Program. The Program encompassed 51 river basins that collectively accounted for more than 70% of the total water use (excluding power generation), and 50% of the drinking water supply in the U.S. The basins represented a variety of hydrologic settings, rock types (geology), land-use categories, and population densities. One aspect of the first cycle included bed sediment sampling; sites were chosen to represent baseline and important land-use categories (e.g., agriculture, urban) in each basin. In total, over 1200 bed sediment samples were collected. All samples were size-limited (< 63 µm) to facilitate spatial and/or temporal comparisons, and subsequently analyzed for a variety of chemical constituents including major (e.g., Fe, Al,) and trace elements (e.g., Cu, Zn, Cd), nutrients (e.g., P), and carbon. The analyses yielded total (≥ 95% of the concentrations present), rather than total-recoverable chemical data.Land-use percentages, upstream underlying geology, and population density were determined for each site and evaluated to asses their relative influence on sediment chemistry. Baseline concentrations for the entire U.S. also were generated from a subset of all the samples, and are based on material collected from low population (≤ 27 p km^− 2) density, low percent urban (≤ 5%), agricultural or undeveloped areas. The NAWQA baseline values are similar to those found in other national and global datasets. Further, it appears that upstream/underlying rock type has only a limited effect (mostly major elements) on sediment chemistry. The only land-use category that appears to substantially affect sediment chemistry is percent urban, and this result is mirrored by population density; in fact, the latter appears more consistent than the former.     

ICP-AES法测定天青石中主次量元素的研究

采用偏硼酸锂熔样,电感耦合等离子体原子发射光谱(ICP-AES)法,对天青石样品实现了一次熔样,主次量元素同时分析。对影响其光谱测量的各种因素进行了较为详细的研究,研究了实验的最佳测定条件。结果表明,方法的检出限为0.0011-0.022lμg·ml-1,回收率为92.87％-106.37％,RSD小于3.89％。该法准确、快速、简便,应用于天青石样品中主次量元素的测定,结果满意。     

Distribution of rare earth elements in anionic,cationic and particulate fractions in boreal humus-rich streams affected by acid sulphate soils

The abundance, fractionation and physicochemical forms of rare earth elements (REEs) were determined in five boreal humus-rich streams (dissolved organic carbon, DOC = 14-40 mg/l) affected by acid sulphate soils. The sampling was carried out during high-water flow in autumn when the acid sulphate soils are extensively flushed. The analytical procedures included ion-exchange experiments in field and ICP-MS determination. There was a general decrease in pH (range 4.5-6.2) and increase in the REE concentrations (La range 0.82-23 microg/l) as the proportion of the catchment cover of acid sulphate soils increased, explained by high amounts of REEs in the acidic runoff from such soils. In each stream, four different REE fractions were identified: (1) A cationic fraction, which is dominant in the REE-rich runoff from the acid sulphate soils and which is depleted in HREEs due to hydrochemical and/or geochemical processes, (2) an anionic fraction identified as humus-REE complexes, which in general is more abundant the higher the DOC concentrations and which also becomes increasingly abundant across the lanthanide series, (3) a fraction having a well-developed MREE enrichment, presumably consisting of colloidal REEs, and (4) a minor uncharacterised particle-associated fraction. The REE pool in the streams thus consists of several coexisting and contrasting REE species. The identification and quantification of such species is a prerequisite for the precise and accurate characterisation of the REE hydrochemistry of the streams.     

大门景观设计艺术浅识

大门具有众多功能实在的景观价值和文化内涵。认识大门与围墙、主体建筑、道路、山水植物及雕塑等要素的景观配置艺术是必要的。     

Blood lead level and its relationship to certain essential elements in the children aged 0 to 14 years from Beijing, China

Objective

To investigate blood lead level and its relationship to copper, zinc, calcium, magnesium and iron in the children aged 0 to 14 years old from Beijing, China.

Methods

We classified 3181 children into one of the four groups: Group A (n = 783, < 1 year old); Group B (n = 1538, 1-3 years old); Group C (n = 443, 3-7 years old); and, Group D (n = 417, 7-14 years old). All these metal elements were determined by atomic absorption spectrometry.

Results

The blood lead level was 0.207 ± 0.105 μmol/L. There was a significant gender difference for zinc (P < 0.05) in Group C, and there was also a significant gender difference for copper (P < 0.05) and lead (P < 0.05) in Group D. Controlling for gender and age, we observed that there was a negative correlation of lead with zinc (r = − 0.052, P < 0.01), magnesium (r = − 0.042, P < 0.05) and iron (r = − 0.031, P < 0.05), respectively. Furthermore, in the children aged 1-7 years old, we also found there was a negative linear correlation of lead with zinc, magnesium and iron, respectively (P < 0.01).

Conclusion

Blood lead level in children from Beijing was markedly decreased. And deficiency of zinc, magnesium and iron is related to the elevated blood lead level in the children aged 1-7 years.     

探求现代空港建筑设计中的地域性--乌鲁木齐地窝堡国际机场航站楼设计随笔

现代航站楼设计追求地域特色必须因地制宜地解决空港中重要的流程、功能、空间、技术、节能等问题。指出将地域要素自然地贯彻过程始终，才能恰当地表达出地域特色。     

空间钢刚架的双重非线性极限分析

本文考虑了材料非线性和几何非线性影响因素,应用荷载—位移逐步增量法,通过自行编制的程序,求算出了空间钢结构刚架的荷载位移全过程曲线。并与单重非线性和双重线性方法分析的结果进行了比较,通过程序计算和试验实测表明,双重非线性有限元法更能真实地反映结构的实际工作。 最后,本文还求出了在各种荷载和各种约束状况下刚架结构双重非线性的极限承载力以及其对应的极限模态。     

灯光元素的数字化描述

基于对灯光元素的分析，引入灯光的特征参数以表征城市灯光景观的效果。并定义了包括光色参数、光形参数、多媒质参数、增强参数和环境参数的特征参数向量和关联矩阵模型，从而建立起进行灯光环境规划的现代数学分析的基础，为系统工程学分析方法应用于城市规划提供了一个平台。