Speciation of Trace Elements in Acidic PoreWaters from Waste Rock Dumps by Ultrafiltration andIon Exchange Combined with ICPMS and ICPOES

A speciation procedure developed on reactive acidicpore water samples from mining areas is presented.Methods with low consumption of solution are requiredthat allow rapid sample preparation to avoid equilibriumchanges as far as possible. The entire procedure includesonly three parallel separation steps. One aliquot is filteredthrough an 1 kd ultrafiltration membrane to separate traceelements adsorbed or complexed by colloids. One cationand one anion exchange are performed with two additionalaliquots to determine simple hydrated ions and smallinorganic complex ions. Commonly used procedures ofion exchange seem to be problematic. This new techniqueis based on a novel ion exchanger. Subsequently the threefractions obtained from the separation procedures and theoriginal pore water sample are analysed by ICPMS, ICPOES,ET-AAS, Flame-AAS, FES and IC to determine the concentrationsof the major ions and additionally up to 50 trace elements. Theinfluence of pH-values and several dissolved compounds iscontrolled in experiment series with synthetically preparedsolutions to reveal potential artifacts.     

A note on Stokes production of turbulence kinetic energy in the oceanic mixed layer: observations in the Baltic Sea

Shear- and convection-driven turbulence coexists with wind-generated surface gravity waves in the upper ocean. The turbulent Reynolds stresses in the oceanic mixed layer can therefore interact with the shear of the wave-generated Stokes drift velocity to extract energy from the surface waves and inject it into turbulence, thus augmenting the mean shear-driven turbulence. Stokes production of turbulence kinetic energy (TKE) is difficult to measure in the field, since it requires simultaneous measurement of the turbulent stress and the Stokes drift profiles in the water column. However, it is readily inferred using second moment closure models of the oceanic mixed layer provided: (1) wave properties are available, along with the usual water mass properties, and radiative and air–sea fluxes needed to drive the mixed layer model and (2) the model skill can be assessed by comparing the model results against the observed dissipation rates of TKE. Comprehensive measurements made during the Reynolds 2002 campaign in the Baltic Sea have made the estimation of Stokes production possible, and in this paper, we report on the effort and the conclusions reached. Measurements of air–sea exchange parameters and water mass properties during the campaign allowed a mixed layer model to be run and the turbulent stress in the water column to be inferred. Simultaneous wave spectrum measurements enabled Stokes drift profile to be deduced and wave breaking to be included in the model run, and the Stokes production of TKE in the water column estimated. Direct measurements of the TKE dissipation rate from an upward traversing microstructure profiler were used to assure that the model could reproduce the turbulent dissipation rate in the water column. The model results indicate that the Stokes production of TKE in the mixed layer is of the same order of magnitude as the shear production and must therefore be included in mixed layer models.     

A GIS based approach to back trajectory analysis for the source apportionment of aerosol constituents and its first application

A new method has been developed to combine back trajectory statistics with a detailed land cover analysis. It provides numeric proxies for the residence times of sampled air masses above certain land cover classes (marine, natural vegetation, agricultural lands, urban areas, and bare areas), as well as further meteorological parameters (mean trajectory length, solar radiation along trajectory, and local height of the boundary mixing layer). The method has been implemented into a GIS-enabled database system to allow for an efficient processing of large datasets with low computational demands. A principal component analysis was performed on a dataset including the modelled residence times, the modelled meteorological parameters, some measured meteorological parameters (wind speed and temperature), and the concentrations of 10 particle constituents (inorganic ions and organic and elemental carbon) in 5 particle size ranges for 29 winter- and summertime samples at an urban background site in Leipzig, Germany. Six principal components could be extracted which together explained about 80% of the total variance in the dataset. The factors could be attributed to the influence of meteorology to continental background pollution, secondary formation processes in polluted air masses, wood burning, aged sea-salt, local traffic, and long-range transported crustal material. The modelled residence times and the meteorological parameters were generally consistent with the existing knowledge of specific particle sources and thereby facilitated and strengthened the interpretation of the factors. Moreover, they allowed for a clear distinction between continental background pollution and secondary formation processes, which has not been possible in previous source apportionment studies. The results demonstrate that the combined usage of back trajectory, land cover, and meteorological data by the presented method yields valuable additional information on the history of sampled air masses, which can improve the quality of source apportionment of atmospheric aerosol constituents.     

Mechanism development and modelling of tropospheric multiphase halogen chemistry: The CAPRAM Halogen Module 2.0 (HM2)

A new detailed multiphase halogen mechanism, the CAPRAM Halogen Module 2.0 (HM2), has been developed and coupled to the multiphase chemistry mechanism RACM-MIM2ext/CAPRAM 3.0n. The overall mechanism comprises 1,705 reactions including 595 reactions of the HM2. Halogen chemistry box model studies have been, for the first time, performed with a non-permanent cloud scenario for pristine open ocean regions in mid-latitudes. Moreover, detailed time-resolved reaction flux analysis has been used to investigate the multiphase halogen reaction cycles in more detail. Clouds significantly change the multiphase halogen chemical system and new reaction cycles are proposed for in-cloud conditions. While most gas phase concentrations are decreased for chlorine and iodine species, they are increased for bromine. Flux analyses determined the relative contributions of the methylene dihalides CH₂IX (X = Cl, Br, I) as the main I atom source with a contribution of about 80 % to the total iodocarbon sources. Furthermore, HOI was confirmed to be important for chlorine activation. It is shown that 25 % of the ozone loss can be attributed to halogens. VOC oxidation by halogens is important as halogens account for about 20 % of the methane oxidation and up to 80 % of the oxidation of other VOCs. In other cases, enhanced VOC and VOC oxidation product concentration levels were found. For example, 15 % of the methyl peroxyl radicals are formed after the reaction of chlorine atoms with methane or methyl hydroperoxide. In the aqueous phase, changes in the oxidation of organics do only occur for highly oxidised organics without a C-H bond. For example, over 80 % of oxalic acid are oxidised by electron transfer with Cl₂ ^? in deliquescent particles during non-cloud periods.     

Particle tracking in the vicinity of Helgoland,North Sea: a model comparison

Station Helgoland Roads in the south-eastern North Sea (German Bight) hosts one of the richest long-term time series of marine observations. Hydrodynamic transport simulations can help understand variability in the local data brought about by intermittent changes of water masses. The objective of our study is to estimate to which extent the outcome of such transport simulations depends on the choice of a specific hydrodynamic model. Our basic experiment consists of 3,377 Lagrangian simulations in time-reversed mode initialized every 7 h within the period Feb 2002–Oct 2004. Fifty-day backward simulations were performed based on hourly current fields from four different hydrodynamic models that are all well established but differ with regard to spatial resolution, dimensionality (2D or 3D), the origin of atmospheric forcing data, treatment of boundary conditions, presence or absence of baroclinic terms, and the numerical scheme. The particle-tracking algorithm is 2D; fields from 3D models were averaged vertically. Drift simulations were evaluated quantitatively in terms of the fraction of released particles that crossed each cell of a network of receptor regions centred at the island of Helgoland. We found substantial systematic differences between drift simulations based on each of the four hydrodynamic models. Sensitivity studies with regard to spatial resolution and the effects of baroclinic processes suggest that differences in model output cannot unambiguously be assigned to certain model properties or restrictions. Therefore, multi-model simulations are needed for a proper identification of uncertainties in long-term Lagrangian drift simulations.     

Laboratory seismic measurements: an aid in the interpretation of seismic field data

This contribution reports data and evidence from laboratory measurements of compressional and shear-wave velocities and mineralogical, microstructural and chemical analyses in crustal rocks that may provide an aid to understanding and interpreting geophysical data. It is shown that the correlation of laboratory seismic data with stratigraphic field data can provide the necessary data base for constructing a seismic model of the Earth's crust in a particular geological area.     

Seasonal to decadal forcing of high water level percentiles in the German Bight throughout the last century

For the purpose of coastal planning and management, especially under changing climatic conditions, enhanced knowledge about the evolution of extreme sea levels in the past, present, and future is required. This paper presents statistical analyses of high seasonal water level percentiles of 13 tide gauges in the German Bight, spanning over a period of up to 109 years throughout the twentieth and twenty-first centuries. Seasonal and annual high percentile time series of water levels were investigated in comparison to the mean sea level (MSL) for changes on seasonal, inter-annual, and decadal timescales. While throughout the first half of the twentieth century extreme water levels generally followed changes in MSL, during the second half of the century, linear extreme sea level trends exceeded those in MSL in the order of 9–64 cm per century. The largest, although insignificant, contribution to the magnitude of these trends occurs in the winter season (January to March), while smaller but, due to the generally lower atmospheric variability, significant changes are observed during spring (April to June). The observed multi-decadal trends are generally in good agreement with multi-decadal trends in the corresponding percentiles of local zonal surface winds. Only small parts of the trends remain unexplained. It is suggested that these remaining trends result from modifications in the local tidal regime. For the aspects of coastal planning, the findings clarify that in the German Bight, in addition to changes in MSL, potential changes in storminess and in the tidal regime significantly contribute to the development of extreme water levels. Since these factors have influenced the characteristic of extremes throughout the recent past, they also have to be taken into account when estimating design water levels for, e.g., dikes (in a warming climate) under changing greenhouse gas emissions.