新疆独山子泥火山沉积物及孔隙水的地球化学特征与流体来源

对陆地泥火山流体来源及其向地表渗漏过程中的改造作用开展研究,有利于加深理解泥火山释放甲烷的碳排放过程。新疆准噶尔盆地南缘独山子泥火山柱状沉积物和地表沉积物的矿物和元素组成,以及沉积物孔隙水离子组成等的分析结果显示,泥火山沉积物孔隙水Na+和Cl–间具有很好的正相关性,具有比海水高的Na+/Cl–和Li+/Cl–值、低的K+/Cl–和Mg2+/Cl–。泥火山沉积物与围岩相比,富集伊利石、绿泥石和方解石,缺少蒙脱石,富集Ca、亏损Si,这些变化主要与黏土矿物的脱水转变有关。表明泥火山流体主要来源于深部低盐度沉积物孔隙水,但经历了地表的蒸发作用,并混合了大气降水。     

基于生物可利用性与宽浓度范围的Hakanson潜在生态风险指数法的创建——以小秦岭金矿区农田土壤为例

Hakanson潜在生态风险指数法是土壤重金属潜在生态风险评价的一种常用方法,研究与实践证明其有效性的同时,也发现了其不足之处:忽略了土壤重金属不同形态之间潜在生态风险的差异,且只重视重金属含量高于参考值时的生态风险,而对低于参考值时的情况没有给予考虑,以致特定情况下的评价结果不能很好地反映实际生态风险,因而有必要创建适用性更广的Hakanson潜在生态风险指数法。为此,基于全过程控制优化的思想,引入了生物可利用性毒性系数,并将修正浓度与参考值差值引入计算公式,创建了基于生物可利用性与宽浓度范围的Hakanson潜在生态风险指数法,实现了对重金属不同形态风险贡献的差异及重金属浓度低于参考值情况下潜在生态风险的准确把握。以小秦岭金矿区为典型区域,辅以对采集土样重金属总量及5种形态含量的分析,开展案例研究。结果表明,基于生物可利用性与宽浓度范围的Hakanson潜在生态风险指数法能客观地揭示土壤重金属的潜在生态风险,具有更大的适应性,是一种有效的潜在生态风险评价方法。     

人工影响天气用碘化银催化剂对区域环境影响的研究进展

中国自1958年以来开展人工影响天气作业。碘化银作为主要的催化剂,是否会对环境造成影响备受关注。分析了国内外使用碘化银开展人工增雨雪和人工防雹外场试验作业后降水、土壤和湖泊等的Ag+含量,尽管催化后Ag+含量会有不同程度的增加,尤其是地面燃烧炉催化和人工防雹作业,但降水和水库中的Ag+含量远低于饮用水标准。统计了我国外场人工影响天气作业的碘化银用量,结合降水和水库中Ag+浓度观测,认为我国人工影响天气使用的碘化银不会对水资源和环境造成影响。     

A Study on the CO Isotopic Lines of the Star Forming Region AFGL 5157

By the mapping observations simultaneously at the ¹²CO (J=1-0), ¹³CO (J=1-0), and C¹⁸O (J=1-0) lines on the area of 24’×24’ (12 pc×12 pc) of the star forming region AFGL 5157, we have obtained the distribution and averaged physical parameters for the respective ¹³CO and C¹⁸O cores of this molecu- lar cloud. At the edge of the molecular cloud, the isotopic abundance ratio is X [(¹³CO)/(C¹⁸O)] ≈ 10, close to the ratio of a giant molecular cloud. The viral masses of the ¹³CO and C¹⁸O cores are less than the masses of the molecu-lar cloud cores, so the molecular cloud cores are gravitationally unstable, and the C¹⁸O molecular cloud core is more easy to collapse. The column density distributions of the C¹⁸O molecular cloud core in the northeast and southwest directions are, respectively, 1.1 × 10²³× z^−0.43 and 4.6 × 10²⁵× z^−0.58, where z is the distance from the center of the molecular cloud core. The high velocity molecular out?ow has been con?rmed from our ¹²CO spectra, the mass loss rate of the out?ow has been estimated, and the mass-velocity relation of the out?ow is ?tted by a power-law function of m ∝ v^−1.8. The star formation rate of the ¹³CO molecular cloud core is as high as 23%, probably, under the in?uence of     

Low velocity shock-cloud encounters I.

Shocks propagating in the interstellar medium (ISM) play an important role in the life of molecular clouds. Through a theoretical study of interaction between clouds and shocks we can understand, for example, the density distribution of observed molecular clouds and the first steps of star formation. The only way to study of interaction in detail is via a numerical hydrodynamical simulation. In this paper we present the first results of a hydrocode which is able to follow the processes after the collision between the cloud and shock front.Our main theoretical result is that the chemical processes (e.g. H₂ dissociation) can affect the dynamical processes significantly. Global parameters of the cloud are calculated for the comparision of the simulation and the observations.     

Dense Gas Diagnostics: Maser Excitation and Variability

I review a number of diagnostic techniques, based upon the excitation and variability of astrophysical masers, which can be applied to dense gas. In each case, I consider the observations necessary and the amount of interpretation, or modelling, required to complete the analysis of a source, presenting examples of each diagnostic method.     

银心区气体分子环的开普勒模型

根据银心区的CO谱线观测 ,对 30 0pc气体分子环提出了一种开普勒模型 :气体分子分布在一个膨胀或收缩的椭圆环上 ,环上的气体分子按开普勒定律绕银心转动。在这样一种模型下 ,气体分子的辐射可以产生类似CO谱线观测的图形。简单讨论了各种模型参数对图形的可能影响     

Spectral Line and Continuum Radiation Propagation in a Clumpy Medium

We discuss the propagation of spectral line and continuum radiation in a clumpy medium and give general expressions for the observed absorption or emission from a cloud population. We show that the affect of the medium clumpiness can usually be characterised by a single number multiplying the mean column opacity. Our result provides a simpler proof and generalization of the result of Martin et al. (1984). The formalism provides a simple way to understand the effects of clumping on molecular line profiles and ratios; for example, how clumping effects the interpretation of ¹³CO(1–0) to ¹²CO(1–0) line ratios. It also can be used as a propagation operator in physical models of clumpy media where the incident radiation effects the spectral line emissivity. We are working to extend the formalism to the propagation of masers in a clumpy medium, but in this case, there are special difficulties because formal expectation values are not characteristic of observations because they are biased by rare events.