地磁低点位移频谱特征及机理探讨

以河北省昌黎地震台为例,使用该台地磁Z分量的分钟值数据,分别对比了正常时段、磁暴发生时段、 低点位移时段的主要频率谱值变化特征. 通过多频点功率谱对数拟合,发现在数据长度相等的情况下,相对于正常时段而言磁暴时段各频率的能量明显增强,特别是高频端尤其明显; 而当大范围低点位移发生时,高频端的能量基本与正常时段持平,但4个小时以上的周期功率谱大部分要低于正常段. 通过对多日低点位移时段的FFT累加与正常时段对比后发现,低点位移发生时,8.5小时和13.7小时周期的频谱值增加. 通过与DE-METER卫星观测的电子密度数据空间图象进行对比,发现地磁低点位移的发生与空间Ne的增加有很好的对应性. 最后对这些变化特征及低点位移可能产生的机制进行了探讨.      

Organochlorine pesticides in fish from the southern Baltic Sea: levels, bioaccumulation features and temporal trends during the 1995-2006 period

The levels of HCH isomers, HCB and summation DDTs were determined in five species of Baltic fish collected during 1995-2006. Some downward time trends of HCH isomer, pp'-DDE and pp'-DDD concentrations in Baltic fish were observed; in contrast, HCB and DDT concentrations did not exhibit any obvious trend. Concentrations of summation HCHs expressed on a lipid weight basis were very similar in all species studied. In contrast, concentrations of summation DDTs varied in tested species. The most abundant HCH isomer was beta-HCH and among DDT-related compounds, pp'-DDE prevailed. In our investigations the sampling sites were not a crucial factor for organochlorine pesticide concentrations and patterns observed in fish, but the occurrence of several inter-species differences in the bioaccumulation features of OC pesticides were observed. For cod there was a positive correlation between fish size (length) and summation DDT concentration. In herring, sprat and salmon samples, summation DDT concentrations were negatively correlated with fat content.     

不同植被覆盖率地区遥感矿化蚀变提取研究

从遥感图像上识别出的围岩蚀变信息往往是一种弱信息。地表植被和第四系覆盖的干扰,增加了遥感蚀变信息提取的难度。为了研究不同植被覆盖条件下的矿化蚀变信息提取方法,分别选取内蒙古西部戈壁荒漠基岩裸露区（温根地区）、中北部中覆盖草原区（达来庙地区）和东北部高覆盖森林草原区（颇格鲁山地区）,利用TM数据进行遥感蚀变信息提取方法研究,得出以下结论：在基岩裸露地区,利用比值法、主成分分析法均能较好地提取出矿化蚀变信息;在中覆盖草原区,利用掩膜对图像进行预处理,再利用主成分分析法提取矿化信息效果比较好;在高覆盖森林草原区,利用掩膜技术和抑制植被信息方法对遥感数据进行综合处理,再利用比值-主成分分析方法能够提取部分矿化蚀变信息。这些方法对今后在类似地区开展遥感蚀变信息提取工作具有一定的指导意义。     

民和黄土粗颗粒组分的气候意义初探

民和黄土各粒径组分含量变化与磁化率曲线对比,并进行相关分析发现：民和黄土〉３０μｍ的粗颗粒组分可以作为较敏感的东亚冬季风代用指标。明确了民和黄土粗颗粒组分与气候变化的良好对应关系。     

永修-南昌剪切带物质成分变异及体积变化研究

永修—南昌剪切带中糜棱岩物质成分变异及体积变化分析结果表明,以Al2O3守恒为限制条件,该剪切带损失了9%的质量和体积,糜棱岩类Fe2O3明显带入,SiO2、K2O、MgO、P2O5、FeO、Na2O等组分明显带出。研究结果显示糜棱岩组分的得失和体积的变化主要发生在初糜棱岩化阶段。     

Keeping things in order: multivariate direct gradient analysis of a strongly fluctuating benthic community

Two spatial surveys of the macrobenthos of an estuarine intertidal area, the Oosterschelde in the southwestern part of The Netherlands, were conducted in different years. In the period between the surveys changes in the hydrodynamics of the estuary took place as a result of the construction of a storm-surge barrier. The works reduced the tidal volume in the basin and as a consequence the altitude of the tidal flats decreased by approximately 0.1 to 0.2 m. Considerable differences in species densities were found between the two surveys, but these large differences could not be explained by changes in the ‘spatial' environmental variables (such as altitude) that were taken into account in a direct gradient analysis. Unknown and ‘only-to-time-related' (e.g. weather-related) factors had considerably influenced species abundance. This implies that the impact of the works on the macrobenthos could not be evaluated on the basis of observed species densities in the before- and after-the-works surveys. Generally, it implies that even if the levels of future ‘spatial' environmental variables are known, direct gradient analysis based on a single survey cannot be used for prediction of future densities in absolute terms in such strongly fluctuating communities. Yet, the gradient analyses for the two years revealed rather similar estimates of the major environmental gradients. The same was true for the parameters that described the relative change in species densities in response to a change in the environmental gradient levels. Hence the most appropriate way of evaluating the changes that have occurred in the benthic community as a result of the works was in terms of the observed changes in the ‘spatial' environmental gradient levels. The levels of the first environmental gradient, which was strongly related to the sediment structure, did not change between years. Levels of the second gradient, which could be interpreted as a tidal zone gradient, decreased. This suggests that the works particularly affected taxa that are strongly related to this second gradient, such as Corophium living in the upper tidal areas and Nephthys living in the lower tidal zone.     

相关观测情况的可靠性研究

可靠性是测量网优化设计和数据质量控制要考虑的重要因素之一。在独立观测情况,测量网的可靠性可用多余度（或称多余观测分量）来表示,多余度越小,该余度越小,该观测位置的可靠性越差,但在相关观测情况,多余度的值域超出（０,１）区间,已不能可靠性特征。本文建议采用一种新的可靠性度量指标：ｒｉ＝（ＰＲ）ｉｉ／Ｐｉｉ,其中Ｐ是观测权阵,Ｒ是平差因子阵。ｒｉ的值域在一种新的可靠性度量指标;ｒｉ＝（ＰＲ）ｉｉ／ｐｉ     

江西大背坞金矿床矿石物质组成及金的赋存状态

大背坞金矿床属贫硫化物（糜棱岩）石英脉型,该矿床有用组分唯有Au,自然金是Au最主要的赋存形式,几乎集中富集了全部Au组分.虽然矿石中有极微量的银金矿,并在方铅矿中发现可能还存在次显微金,但含金量却微不足道.石英、黄铁矿、毒砂是自然金的主要载体.自然金成色高,多以中粗粒裂隙金形式产出,粒间金次之,包裹金较少.本矿床中黄铜矿、方铅矿、闪锌矿不发育,含量少,但它们与自然金关系密切,镜下常常发现与自然金共生赋存于较粗粒的黄铁矿、毒砂等载金矿物中.这3种硫化物是发现富矿化的标志.铅同位素结果表明本金矿成矿物质来源于前震旦纪变质沉积岩,中元古界双桥山群是矿源层.金以络合物的形式迁移.当温度降低（低于300℃）,含矿溶液进入容矿空间压力降低,金发生沉淀.矿化早期石英脉包裹体pH值4.91,Eh值164.52,到矿化主期pH升高到6.38~6.72,Eh降低到57.44,从而使金在溶液中的溶解度大大降低,促使金发生沉淀.     

Beach Litter Sampling Strategies: is there a ‘Best’ Method?

Ten methods for sampling beach litter were tested on 16 beaches located around the Firth of Forth, Scotland in order to ascertain the effectiveness of the various methods. Both fresh and/or accumulated litter were sampled. Some methods were more effective for recording gross amounts of litter. Maximum litter counts could be obtained by surveying the top boundary of the beach (e.g. vegetation line, retaining wall, rocks). Lowest amounts were obtained by surveying one five metre wide belt transect from the vegetation line to the shore. Some bias towards highlighting particular litter types was shown by specific methods. It was concluded that there were advantages and disadvantages for each method and that the aims of the study would in the end determine the method.     

用活有孔虫分布指示三亚汊道外港潮流格局

由因子分析得知,海南岛三亚湾汊道外港海底分布有四个主因子活有孔虫群,它们分别代表海湾内水体、湖冲出半盐水水体、湾外内陆架水体及内陆架与海湾水相混的过渡水体.这些水体在潮汐作用下的运动、相互混合,可由各水体的有孔虫指示.由每个主因子因子得分最高的三个属种百分含量之和等值线图所指示的外港潮流循环格局,与海洋学研究所得的结果相当一致.利用有孔虫指示潮汐汊道潮流格局尚属首次尝试,这方法对海岸开发分析泥沙运动、污染物排放等有实践意义.