Four thousand years of atmospheric lead pollution in northern Europe: a summary from Swedish lake sediments

This paper presents a large palaeolimnological study of the pre-industrial and industrial history of atmospheric lead pollution deposition in Sweden. Both lead concentrations and ²⁰⁶Pb/²⁰⁷Pb ratios have been analysed in 31 lakes covering most of Sweden, plus one lake in north-west Russia. Four of the lakes have varved (annually-laminated) sediments. Isotope analysis is a sensitive and effective method to distinguish pollution lead from natural catchment lead and to detect early pollution influence, because the ²⁰⁶Pb/²⁰⁷Pb ratio in unpolluted background sediments in Sweden was > 1.3, while that of lead from pollution, derived from ores and coal, was < 1.2. The sediments show a consistent picture of past temporal changes in atmospheric lead pollution. These changes include: the first traces of pollution 3,500-3,000 yrs ago; a pollution peak in Greek-Roman Times (about 0 AD); lower lead fall-out between 400 and 900 AD; a significant and permanent increase in atmospheric lead fall-out from about 1000 AD; an increase with the Industrial revolution; a major increase following World War II; the maximum peak in the 1970s; and decreasing fall-out over the last decades. The four varved sediments provide high-resolution records of atmospheric pollution. They reveal pollution peaks about 1200 and 1530 AD which match the history of metal production in Europe. According to the varve records the lead pollution level in the late 1990s had decreased beneath the level of the 1530s. The pollution level 1200 AD was about 35% of the 1980s, when lead pollution was still near its all time high. About 50% of the total accumulated atmospheric lead pollution deposition through time was deposited in the pre-industrial period. The sediments also show a consistent picture of the geographic distribution of atmospheric lead deposition over time, with higher deposition in south Sweden and declining levels to the north, which supports the hypothesis that the main sources of pre-industrial atmospheric lead pollution in Sweden were cultural areas in mainland Europe and Great Britain.     

The relief of the Swiss Alps and adjacent areas and its relation to lithology and structure: topographic analysis from a 250-m DEM

In this paper we discuss the large-scale geomorphological characteristics of the Swiss Alps based on numerical analysis of a digital elevation model and compare these to an erodibility map constructed from a geotechnical map of Switzerland and regional geomorphological studies. Comparing the erodibility map with the large-scale morphometry shows an intimate relationship between mountain-scale erodibility and topography. On average, higher mean elevations and steeper mean slopes correlate with regions where rocks of low erodibility prevail. Areas with high peaks as well as the main water divides are controlled by the presence of bedrock with low to very low detachability. The drainage network of the Swiss Alps shows a close relationship to the lithological differences as well. Major longitudinal valleys follow easily erodible units. In the eastern and western part of the Swiss Alps, the highest values of local relief are located to the south of the main water divide, whereas in the central part, local relief is higher to the north of the main water divide. The large-scale geomorphic characteristics regarded in the framework of the geological history of uplift and denudation suggest that low and very low erodibilities lead to the development of areas of high elevations which are likely to persist over periods of 10–15 Ma. As the analysis of the Lepontine area shows, 20 Ma after cessation of exhumation, such high elevations are likely to be worn down and to manifest themselves as high relief only.     

波西米亚块体西部长周期电磁研究(英文)

在波西米亚块体西南部做了一条长周期电磁剖面 ,它靠近德国超深钻的位置。用一个二维合成模型对数据做了大体的拟合 ,模型走向东西 ,近地表盖层高度地不均匀畸变。畸变层显示强烈的各向异性 ,优势电导方向为NW -SE至NNW -SSE。讨论了深部区域结构的几个不同的模型 ,其中一个模型可以解释由MT和GDS数据显示的主方向的偏差 ,还讨论了沿特别剖面得到的结果与区域地电结构的关系     

On the meridional circulation and balance of momentum in the Southern Ocean of POP

 The circulation of the Southern Ocean is studied in the eddy-resolving model POP (Parallel Ocean Program) by an analysis of zonally integrated balances. The TEM formalism (Transformed Eulerian Mean) is extended to include topography and continental boundaries, thus deviations from a zonally integrated state involve transient and standing eddies. The meridional circulation is presented in terms of the Eulerian, eddy-induced, and residual streamfunctions. It is shown that the splitting of the meridional circulation into Ekman and geostrophic transports and the component induced by subgrid and Reynolds stresses is identical to a particular form of the zonally integrated balance of zonal momentum. In this balance, the eddy-induced streamfunctions represent the interfacial form stresses by transient and standing eddies and the residual streamfunction represents the acceleration of the zonal current by density fluxes in a zonally integrated frame. The latter acceleration term is directly related to the surface flux of density and interior fluxes due to the resolved and unresolved eddies. The eddy-induced circulation is extremely vigorous in POP. In the upper ocean a shallow circulation, reversed in comparison to the Deacon cell and mainly due to standing eddies, appears to the north of Drake Passage latitudes, and in the Drake Passage belt of latitudes a deep-reaching cell is induced by transient eddies. In the resulting residual circulation the Deacon cell is largely cancelled and the residual advection of the zonal mean potential density is balanced by diapycnal eddy and subgrid fluxes which are strong in the upper few hundred meters but small in the ocean interior. The balance of zonal momentum is consistent with other eddy-resolving models; a new aspect is the clear identification of density effects in the zonally integrated balance. We show that the wind stress and the stress induced by the residual circulation drive the eastward current, whereas both eddy species result in a braking. Finally, we extend the Johnson–Bryden model of zonal transport to incorporate all relevant terms from the zonal momentum balance. It is shown that wind stress and induction by the residual circulation carry an eastward transport while bottom form stress and the stress induced by standing eddies yield westward components of transport. Received: 26 June 2001 / Accepted: 2 November 2001     

A fractal-multifractal approach to groundwater contamination. 2. Predicting conservative tracers at the Borden site

 In a companion paper (Puente et al., this issue), the capability of a deterministic fractal-multifractal (FM) approach to faithfully and compactly describe the geometry of chloride and bromide tracers gathered at the Borden site was illustrated. As trends in surrogate parameter space were found for successive plume contours (i.e. linear growth in coordinates by which fractal interpolating functions pass, nearly constant rotations and fairly high scalings), this article reports usage of a variety of prediction schemes, based on linear regressions and the aforementioned trends, in order to study the evolving plumes. It is shown that the FM representation leads to plausible non-Gaussian plume evolutions and yields predictions that closely approximate records for a period of time that extends even beyond one year. It is illustrated that such predicted geometries are also consistent with predictions made via stochastic theories (i.e. Dagan, 1984).     

Evolutionary properties of stochastic models of earthquake accelerograms: Their dependence on magnitude and distance

An approach to generate artificial earthquakeaccelerograms on hard soil sites is presented. Eachtime-history of accelerations is considered as arealization of a non-stationary gaussian stochasticprocess, with statistical parameters depending onmagnitude and source-to-site distance. In order tolink the values of these parameters for each groundmotion record with the corresponding magnitude andsource-to-site distance, semi-empirical functionalrelations called generalized attenuationfunctions are determined. The set of realground-motion time histories used to obtain thesefunctions correspond to shocks generated at differentsources and recorded at different sites in thevicinity of the southern coast of Mexico. The resultsshow significant dispersion in the parameters of themodel adopted, which reflect that associated with thereal earthquakes included in the sample employed.The problem of conditional simulation of artificialacceleration time histories for prescribed intensitiesis briefly presented, but its detailed study is leftfor a companion paper. The criteria and modelsproposed are applied to generate two families ofartificial acceleration records for recurrenceintervals of 100 and 200 years at a specific sitelocated in the region under study. The results shownin this article correspond to acceleration timehistories recorded on firm ground for earthquakesgenerated at the subduction zone that runs along thesouthern coast of Mexico, and cannot be generalized tocases of earthquakes generated at other sources orrecorded at other types of local conditions. Thismeans that the methods and functional forms presentedhere are applicable to these other cases, but thevalues of the parameters that characterize thosefunctions may differ from those presented here.     

Model of Formation and Development of Spring Thermal Bar

A mathematical model simulating the thermo- and hydrodynamic processes near the thermal bar in the period of lake warming in spring is considered. A closed system of Reynolds type equations is constructed based on the Navier–Stokes nonlinear system of equations using the Boussinesq approximation and a special technique for isolating large-scale structures in turbulent medium. The turbulent viscosity coefficient is evaluated in the course of problem solution. The results of calculations are shown to agree well with field observation data.     

Stochastic delineation of wellhead protection area in fractured aquifers and parametric sensitivity study

 In many countries, the setup of protection areas around every drinking water well was instituted at a national level in order to preserve the quality of water as well as the perennially of the resource. Wellhead protection surfaces have been defined using capture zones showing the area influenced by a well within a certain time. A stochastic method is developed for delineating time-related capture zones in fractured aquifers characterised by a low porosity and a high degree of fracturing. The flow velocity within the fractures is determined statistically depending on the distribution of the fracture features and the mass transfer solution is obtained through a particle tracking algorithm. Probabilistic capture zone curves are obtained as a function of the travel time of particles to the well and the percentage of particles apt to be extracted up to this time. A sensitivity study of fracture network parameters leads to the conclusion that orientations and aperture distribution of the fracture sets are of primary importance to the wellhead protection delineation.     

Diurnal Variations in the Hydrochemical Indices in Amur Bay

A study was conducted to assess the diurnal variations in water temperature, in-situ density, and salinity; major components of the salt composition; ion–chlorine relationships; elements of the carbonate system and their chlorine ratios; major nutrient compounds; total organic carbon content; suspended matter; dissolved oxygen and its percentage in the coastal waters of Amur Bay. The notions of zero, very small, small, medium, high, and very high relative variability are introduced.