云层与气溶胶对大气吸收太阳辐射的影响

云通过辐射过程对地气系统的能量平衡起着特别显著的调节作用 ,是影响天气、气候以及全球变化的重要因子。近年来 ,有云大气对太阳短波辐射的“异常吸收”又成为云—辐射研究中的一个争论热点。有云大气的短波吸收受到多种因素的影响 ,关于这方面的研究还不够充分。本文通过计算 ,从理论上探讨了若干因素的组合对大气吸收的综合影响。在计算中 ,同时考虑了不同太阳辐射波段、不同太阳入射天顶角、不同云顶高度以及不同下垫面的影响 ,并考虑了包含大气分子、气溶胶和云滴的吸收与散射 ,以及在近红外波段大气自身的热辐射等过程 ,阐明了云与气溶胶在不同波段对大气吸收太阳辐射的影响。     

Mercury-tainted overbank sediment from past gold mining in north Georgia, USA

 Gold was discovered in 1829 and mined until about 1940 in north Georgia, particularly within an area known as the Dahlonega mining district. The mining operations there, which involved mercury amalgamation in stamp mills and sluices, delivered significant quantities of mercury waste to streams. This paper focuses on the downstream dispersal and storage of mercury in streambank sediments of two watersheds near Dahlonega, Georgia. Mercury concentrations for individual samples of historical sediment range from 0.02 to 12.00 ppm, with average values in streambanks near the core of the mining district ranging from 0.2 to 0.6 ppm. Mercury levels rapidly decrease in the downstream direction to concentrations that are slightly above a background level of 0.04±0.02 ppm. Mercury concentrations also appear to decrease with increasing distance from streambanks. Similar levels of mercury contamination from former gold mines probably exist in many other parts of the gold-bearing rocks of the Piedmont of the eastern United States. The bioavailability and environmental hazard posed by the contaminated sediment is not certain. Received: 8 January 1996 · Accepted: 29 May 1996     

强天气冷涡云系结构的分析和物理解释

本文分析了三个产生强对流天气冷涡过程的卫星云图.冷涡云系的结构可归纳为单纯的冷涡结构和具有锢囚气旋结构两类.利用诊断分析对冷涡云系中各个组成部分,即涡旋云区、不稳定云区、正涡度平流云区、冷涡云区及暖锋云区与有关物理量的配置关系进行了讨论.     

西太平洋热带海域的水汽和云的变化特性

本文依据1987年9—11月西太平洋热带海域海洋大气综合考察中双波长微波辐射计观测系统和红外窗区辐射计所得到的观测资料,分析研究了考察海域的水汽和云的变化特性,得到了一些有意义的结果。双波长微波辐射计观测系统可以获得水汽场的动态变化和云中液态水的演变;西太平洋海域的个例显示出辐合区的垂直气柱水汽含量比非辐合区的明显大的特征;用红外亮度温度可以近似估计晴空大气垂直气柱水汽含量。     

对流云中冰相过程的三维数值模拟——Ⅱ:繁生过程作用

在可压缩三维冷云数值模式里对冰晶繁生过程进行了参数化,显式考虑了过冷滴冻结破裂和Hallett-Mossop两个繁生机制,并对冰晶浓度进行了订正。对暖底孤立积云的模拟实例表明繁生作用对对流系统宏观特征没有显著改变,地面总降水略有增加,最大雨强增大且时间提前。繁生过程的主要作用是改变了云的微物理结构特征,使云中冰化时间提早,冰化程度大大加强,引起云上部增暖并抬高云顶。在所考虑的两个繁生机制中,冻结破裂繁生机制是引起微物理结构发生变化的主要过程。还对各冰相微物理过程的相对作用进行了分析。     

沉积物污染和环境沉积学

环境沉积学着重研究人类活动与沉积循环（包括风化作用、侵蚀作用、沉积作用和早期成岩作用）相互间的影响,寻求人类与自然协调发展的更佳方式。现在,全球河流、湖泊和海洋中沉积物污染严重,沉积学家应予以关注并为解决由此所产生的环境问题做出贡献。实际上,为了对沉积物环境质量进行评估和治理被污染的环境,需要沉积学家去研究污染物的时空分布与岩相、沉积相和沉积体系之间的相互关系,研究污染物在沉积作用和早期成岩作用中的行为,研究沉积物中污染物的存在形式等重要课题。     

基于云GIS的遗址保护数据共享服务研究

遗址保护的多学科综合研究特征以及考古学的不可逆性、不确定性,使遗址数据的共享成为一项紧迫的工作。本文通过对遗址保护过程的分析及遗址保护相关单位的分类,提出了遗址数据"授权使用,分级共享;远程使用、保证安全;限时使用,有偿服务"的共享原则和集中管理的共享服务模式。结合当前云计算和大数据的发展趋势,研究提出了基于云计算平台的遗址保护数据共享平台总体框架,并对总体框架中的遗址考古公共服务云GIS平台进行功能设计,以石峁遗址为例,实现遗址数据资料在公共服务平台上的发布、展示、查询浏览及遗迹模拟展示。     

东亚夏季风活动与不同类型云的相关性研究

利用1998~2007年候平均卫星-台站融合降水资料以及ISCCP (International Satellite Cloud Climatology Project) D1云资料,分别定义了标准降水指数和两类云指数。降水指数大值区的移动能很好的表征东亚夏季风活动,两类云指数能分别反映某个区域深对流云(DC)、高积云(Ac)和积云(Cu)云量的集中变化特征。根据不同地区降水集中时段以及降水量等气候特征,结合中国气候区划(温度带及干湿区)及不同地域的地形特征,把中国大陆受东亚夏季风影响的地区划分为五个子区域。利用ISCCP D1云气候资料和降水资料,在候时间尺度上通过分析降水与不同云类、标准降水指数与两类云指数的相关性研究了东亚夏季风活动与不同类型云的对应关系。研究表明:ISCCP定义的深对流云(DC)、卷层云(Cs)与降水量在五个区显著正相关,表明东亚夏季风活动伴随有大量的对流云及云砧出现;高积云(Ac)、积云(Cu)的总云量与降水量在五个区显著负相关,表明夏季风活动增强时,Ac和Cu云量减少;层云(St)和层积云(Sc)与降水量在南方和北方分别呈显著的负相关和正相关,说明季风活动在南方伴随着对流云的显著增加,在北方则使层状云和对流云均有所增加;高层云(As)、卷云(Ci)和雨层云(Ns)与季风活动没有显著的相关性。     

Spatial distribution,environmental assessment and source identification of metals content in surface sediments of freshwater reservoir,Pakistan

Surface sediments were collected from different sites of a freshwater reservoir, Pakistan, and analyzed for eight metals (Cd, Co, Cr, Cu, Fe, Mn, Pb and Zn) using flame atomic absorption spectrometry. The estimated metals levels were found higher than other reported studies. The environmental indices including geoaccumulation index, enrichment factor and contamination factor identified Cd, Co, Pb and Zn as the priority pollutants of concern. Chromium, Cu and Mn were also found to be enriched in some areas. The pollution load index (≥1) indicated progressive deterioration of the sediments quality. Principal component and cluster analyses revealed that Cd, Co, Pb and Zn were mainly originated from agricultural activities, domestic wastes, road runoffs and recreational activities. Chromium, Cu, Fe and Mn were mainly derived from natural sources though Cr, Cu and Mn were partially contributed by human inputs. Based on spatial distribution, inlet and middle sites of the reservoir were found more contaminated. This study would drive urgent attention to develop preventive actions and remediation processes for aquatic system protection and future restoration of the reservoir.     

Spatial variability of soils and stream sediments and the remediation effects in a Portuguese uranium mine area

The old Senhora das Fontes uranium mine, located in central Portugal, was closed down in 1971. The treatment of ores from this mine and other mines by heap-leach ended in 1982. Seven dumps partially covered by vegetation were left in the area. Soil and stream sediment samples were collected in December 2009. The remediation was carried out from May 2010 to January 2011. Stream sediment samples were collected again in October 2013. Before the remediation, soils from inside the mine influence area have higher Al, As, Co, Cr, Cu, Fe, Ni, Sr, Th, U and Zn concentrations than soils from outside this area, due to radionuclides, metals and metalloid released from the mine dumps. The principal component analysis (PCA) shows a distinction between soils from inside and outside the mine influence area. The U(VI), As(V) and metals from soils can be adsorbed to Fe-oxyhydroxides and the humic acid can increase the U uptake. Soils must not be used for public or private green and residential areas, because they are contaminated in U, As, Co, Cd and Ni. Before the remediation, downstream sediments have higher Al, As, Cu, Mn, Ni, Pb, U and Zn than upstream sediments, due to erosion and percolation of water through the mine dumps. The PCA shows a distinction between downstream and upstream sediments. The U(VI), Th and As(V) can be adsorbed to Fe-oxyhydroxides. The stream sediments are contaminated in As, Mn, Th and U. Downstream sediments are the most contaminated in U and As. After the remediation, upstream and downstream sediments have generally higher Al, Fe, As, Cr, Ni, Th, U and Zn concentrations than before the remediation, attributed to the relocation of dumps. Radionuclides, metals and metalloids were transported by surface water. Consequently downstream sediments have higher Al, As, Cu, Mn, Ni, Th, U and Zn concentrations than upstream sediments. The U(VI), Th and As(V) can be adsorbed to Fe-oxyhydroxides. Stream sediments became more contaminated in U, Th and As than before the remediation, but more intensively downstream.