Geomagnetic spherical harmonic analysis

Summary An attempt is made to determine the optimum representation of the geomagnetic field in terms of spherical harmonics with regard to the number of parameters required for an adequate accuracy of fit, and considering the effect of allowing for the oblateness of the earth. A representative set of geomagnetic data was subjected to a set of analyses with from 8 to 120 coefficients for both spherical and oblate models of the earth. It is concluded that a sixth order analysis (48 coefficients) with no allowance for oblateness is the most compact representation of the field compatible with tolerable accuracy.     

150 years of magnetic observatories: Recent researches on world data

A joint Discussion Meeting of the Royal Astronomical Society and the Royal Irish Academy, held on January 11th, 1991, commemorated the establishment of some early magnetic observatories, discussed recent research using global geomagnetic data and described the present status of magnetic observatories in the United Kingdom. The observatory and instruments at the Dublin magnetic observatory; the origins of the Greenwich magnetic observatory, and why it eventually had to be resited; and the history of the Munich magnetic observatory formed the historical part of the proceedings. Current research topics discussed were the geomagnetic secular variation and deep Earth structure and dynamics; fluid flow patterns near the top of the core; the origin of the annual variation of the geomagnetic field; results of an analysis of monthly means from some British observatories; a new theory of the geomagnetic daily variation; and the interactions between ionospheric science and geomagnetism. The present-day observatory scene was described in terms of the information that can be derived from the almost 40 year series of data from Hartland magnetic observatory; of the methods used to process data from the three UK magnetic observatories, which nowadays are operated automatically and remotely; and (a look into the future) of a new project, INTERMAGNET, which aims to make available, in near real time, data from the world-wide network of magnetic observatories.     

PCB contamination from sampling equipment and packaging

Work reported in this paper suggests that there are cases of contamination of soil and water samples by polychlorinated biphenyls (PCB) from paper and plastic packaging. Soil samples, which have been stored in paper bags for more than 20 years, share a similar congener distribution as the bags. Analyses showed a predominance of light congeners. PCB-analyses of water also indicate that water samples could be contaminated by plastic packaging. All analytical results of solid material packaging, as well as soil stored in the packaging, show a high relative amount of light weight PCB congeners. The paper bags that were analysed are made of strong paper and very popular among geochemists because of their watertight quality. These paper bags were manufactured more than 20 years ago. The plastic packaging that was analysed was produced in 1997 and 2008. The analyses of plastic and paper show that the raw material that has been used in the production at different times contains a wide concentration range of PCB. Re-sealable plastic bags, which contained the highest levels of PCB of the plastic material, are used by researchers world-wide as sampling bags for soils and sediments. This paper raises an important issue that packaging may potentially contaminate the samples that they hold.     

Geomagnetic signature of the 1999 August 11 total eclipse

The magnetic north ( H ), magnetic east ( D ) and vertically downward ( Z ) components of the geomagnetic field were monitored at Elazıgˇ, Turkey, with a three-component fluxgate magnetometer during the 1999 August 11 total eclipse of the Sun. The results were compared with those obtained with an identical instrument at Kandilli magnetic observatory, which is at a similar latitude to Elazıgˇ, but clear of the band of totality. An increase of D is found during the eclipse, rising to a maximum close to the time of maximum eclipse. The reality of this effect is confirmed by noting a similar feature, also centred on the time of eclipse, at a number of European observatories.     

小样本数据下安徽省经济-环境系统协调发展的实证分析

作为一个非线性复杂系统,经济与环境之间相互作用,两者之间如果彼此协调,就能推动社会的可持续发展,反之则会阻碍社会的发展,中国各省份情况概莫能外。使用主成分分析和环境与经济系统协调度计量模型,对安徽省2000-2010 年的经济—环境协调状况进行了定量分析,计算出该省经济—环境之间的协调度;然后利用基于IOWA算子的组合预测方法,对小样本数据进行外推预测;进而给出"十二五"期间实现安徽省经济—环境系统协调发展的政策建议,指出当地政府在制定相应公共政策时,应对本地区经济—环境系统影响较大的因子予以格外关注,同时要避免地区之间争夺区域外投资的恶性竞争,否则将不利于经济—环境系统的协调发展。     

Release and transformations of inorganic iodine by marine macroalgae

A number of field and laboratory studies on the impact of marine macroalgae on dissolved inorganic iodine speciation are presented. Within tidally isolated rock pools, the brown macroalga Fucus serratus was found to both release stored iodide and to facilitate the reduction of iodate to iodide. In contrast, no discernible changes in iodine speciation were observed in rock pools containing green macroalgae of the genus Ulva. Incubation experiments confirmed that the macroalgae Laminaria digitata, F. serratus and Kallymenia antarctica release iodide, though the rate of release varied between species and between specimens of the same species. Application of oxidative stress by treatment with cell wall derived oligoguluronate elicitors increased the efflux of iodide by L. digitata approximately 20-fold. The release of iodide by macroalgae may impact upon the formation of volatile iodine species (molecular iodine and iodocarbons) that are of importance in the coastal atmosphere.