湘西汞矿区土壤中重金属的空间分布特征及其生态环境意义

采用HG-ICP-AES和ICP-MS法测定了湘西茶田汞矿区典型土壤剖面（远离矿口处的自然土壤剖面P₁、矿口附近的自然土壤剖面P₂和汞矿渣下覆土壤剖面P₃）不同层次的土壤及矿区的矿石、废矿和矿渣等环境样品中Hg及其它重金属的含量,在此基础上,结合富集系数法和相关分析等地统计学方法,探讨了汞矿区土壤中Hg等重金属的来源、分布及迁移特征.结果表明,Hg在P₁剖面中呈底层富集趋势,而在P₂、P₃剖面中均表现出明显的表层富集现象;P₂、P₃剖面土壤都遭受了Hg的污染,但P₃的污染更为严重,其土壤表层的Hg含量达到640 　μg·g^-1,剖面Hg平均含量为(76.74±171.71) 　μg·g^-1,Hg向下迁移的深度超过100 cm,分别高于P₂的6.5 　μg·g^-1、(2.74±1.90) 　μg·g^-1和40 cm;除成矿元素Hg污染严重外,矿区土壤中还存在着Cd、As、Pb、Zn的污染,且以Cd的污染较为严重;矿区土壤剖面中重金属的迁移能力为Hg>Cd>As>Zn ≈ Pb,并受元素在表土层的含量及土壤理化参数的影响.研究表明,矿区土壤剖面中重金属的来源、分布及迁移既受原生地质环境的影响,更与人类采选矿活动密切相关.     

黄土沟壑区小流域不同地形下土壤微量元素分布特征

研究了黄土沟壑区小流域塬面、坡地、梯田和沟道土壤微量元素的剖面分布特征,以揭示不同地形条件下微量元素的有效性及地球化学特性.结果表明,不同土层土壤全量微量元素的变异系数均小于15%,为小变异土壤性质,有效态和吸附态铁和锰的变异系数均高于36%,为高度变异土壤性质;有效态和吸附态锌和铜属于中到高度变异.全量铁、锰和铜以沟道土壤较高,全锌、有效态和吸附态微量元素含量以塬面土壤较高.不同形态微量元素的剖面分布趋势取决于地形条件.不同地形下成土过程及不同地形条件所对应的土地利用方式造成了全量微量元素的差异,而土壤有机质含量的差异是不同地形条件下有效态和吸附态微量元素剖面分布特征不同的主要原因.     

美国海军F-18飞机中的“使用任务环境法”

介绍了美国海军F-18飞机采用的使用任务环境（OME）法,重点分析了F-18飞机合成任务剖面、主要环境因素和完整性试验大纲,简述了F-18飞机OME法在可靠性水平增长及寿命期费用节省等方面取得的成果。     

装备全寿命环境剖面与任务剖面

评估和提升装备的战备完好性和任务成功性,必须掌控装备的全寿命剖面,特别是全寿命环境剖面和全寿命任务剖面。论述了环境剖面和任务剖面之间的关系和界定原则,提出了环境剖面的确定方法,阐述了组成任务剖面的作战使用剖面和非作战使用剖面的确定步骤和应该考虑的要点。     

固体发动机典型环境载荷分析

分析了固体发动机在贮存、运输、发射等使用条件下的环境载荷,为下一步编制固体发动机环境载荷谱和试验研究提供了基础。     

贵州茂兰峰丛森林洼地泥沙堆积速率的~(137)Cs示踪研究

选择黔南峰丛洼地区的茂兰自然保护区的坡格森林洼地典型小流域,进行了泥沙堆积的137Cs示踪研究。(1)坡格森林洼地底部的土壤剖面属于农耕地剖面。(2)受岩土分布、微地形和土壤异质性的影响,137Cs初始沉降后的再分布不均匀,137Cs面积活度变异系数为1.54。相同组成特征的地块内部样点137Cs面积活度变异系数变化为0.36～0.54,变异相对较小。但137Cs面积活度不能表征土壤侵蚀状况。(3)典型沉积剖面B-1的单一137Cs峰值浓度出现在14～16cm,高浓度137Cs均匀分布深度小于当地犁耕层厚度20cm,说明1963年以来坡格森林洼地的堆积速率接近于0。     

Distribution of polybrominated diphenyl ethers and decabromodiphenylethane in surface sediments from Fuhe River and Baiyangdian Lake, North China

Nineteen surface sediment samples collected from Baiyangdian Lake and its inflowing river (Fuhe River) in North China were analyzed for polybrominated diphenyl ethers (PBDEs) and decabromodiphenylethane (DBDPE). The concentrations of PBDEs and DBDPE in sediments ranged from 5.5 to 300.7 ng/g dry weight (dw) and 1.1 to 68.2 ng/g dw, respectively. Their levels in sediments in Fuhe River were significantly higher than those in Baiyandian Lake. Compared to data from other regions, the PBDE levels in surface sediments from Baiyangdian Lake and Fuhe River were in the medium to lower range. Among the PBDE congeners, BDE209 was predominant, with contributions to the total PBDEs ranging from 79.4% to 97.3% in sediment samples. For the lowly brominated congeners (tri- to hepta-BDE), BDE47 and BDE99 were the most abundant, which contributed 52.1% and 44.1% to the sum of tri- to hepta-BDEs in the sediments from Baiyangdian Lake and Fuhe River, respectively. The compositional patterns of PBDEs in Baiyangdian Lake sediments indicated that technical deca-BDE mixture was the major pollutant sources with a minor contribution of penta-BDE mixture. The present study suggested that the importance of Fuhe River as a possibly potential sources of PBDEs contamination in Baiyangdian Lake.     

Effects of elevated atmospheric CO2 concentration and temperature on the soil profile methane distribution and diffusion in rice-wheat rotation system

The aim of this experiment was to determine the impacts of climate change on soil profile concentrations and diffusion effluxes of methane in a rice–wheat annual rotation ecosystem in Southeastern China. We initiated a field experiment with four treatments:ambient conditions(CKs), CO_2 concentration elevated to ~ 500 μmol/mol(FACE),temperature elevated by ca. 2°C(T) and combined elevation of CO_2 concentration and temperature(FACE + T). A multilevel sampling probe was designed to collect the soil gas at four different depths, namely, 7 cm, 15 cm, 30 cm and 50 cm. Methane concentrations were higher during the rice season and decreased with depth, while lower during the wheat season and increased with depth. Compared to CK, mean methane concentration was increased by 42%, 57% and 71% under the FACE, FACE + T and T treatments, respectively, at the 7 cm depth during the rice season(p 0.05). Mean methane diffusion effluxes to the 7 cm depth were positive in the rice season and negative in the wheat season, resulting in the paddy field being a source and weak sink, respectively. Moreover, mean methane diffusion effluxes in the rice season were 0.94, 1.19 and 1.42 mg C/(m~2·hr) in the FACE,FACE + T and T treatments, respectively, being clearly higher than that in the CK. The results indicated that elevated atmospheric CO_2 concentration and temperature could significantly increase soil profile methane concentrations and their effluxes from a rice–wheat field annual rotation ecosystem(p 0.05).     

基于贮存剖面的弹上电子部件可靠性分析

目的 提高弹上电子部件贮存可靠性预测的准确度,提出基于贮存剖面的弹上电子部件可靠性分析方法。方法 在分析弹上电子部件贮存剖面及环境条件的基础上,将弹上电子部件视为多阶段任务系统,引入贝叶斯分析,采用分阶段建模方法,针对各阶段相关性和失效率的不同,基于累积损伤模型,构建弹上电子部件贮存寿命周期内的可靠性模型。结果 相比于洞库贮存、值班等单一环境条件下的可靠性预测,基于贮存剖面综合环境下的可靠性预测结果的准确性更高,且随着贮存时间的增长,优势更明显。结论 该方法立足于实际贮存剖面,分析结果更符合弹上电子部件的应用实际,也为其他弹上部件的可靠性分析提供了一种有效途径。     

Polycyclic aromatic hydrocarbons in soils of Beijing and Tianjin region： Vertical distribution, correlation with TOC and transport mechanism

The contents and distribution of 20 polycyclic aromatic hydrocarbons (PAHs) and heterocyclic aromatic hydrocarbons (HAHs) were investigated in 16 soil profiles of Beijing and Tianjin region. Transport of high molecular weight PAHs (HMWPAHs) and the correlation between total organic carbon (TOC) and their concentrations were also discussed. The results indicated that highly contaminated sites were located at urban or wastewater irrigation areas and pollutants mainly accumulated in topsoil (< 40 cm), with a sharp content decrease at the vertical boundary of 30–40 cm. Total PAHs/HAHs concentrations in soils from Tianjin were markedly greater than those from Beijing. Even the contents at bottoms of soil profiles in Tianjin were higher than those in topsoils of Beijing soil profile. HMWPAHs dominated the PAH profiles, exhibiting a uniform distribution of pyrogenic origin between topsoils and deep layers. Furthermore, the percentages of HMWPAHs remained relative constant with the depth of soil profiles, which were consistent with the distribution of particulate matter-associated PAHs in the local atmospheric environments. Therefore, HMWPAHs transport with particulates might be the predominant source found in soil profiles.