Some aspects of the interaction of humic substances with metal ions

Humic substances are the major organic constituents of soils and sediments. They are heterogeneous, polyfunctional, polydisperse, macromolecular and have no accurately known chemical structure. Their interactions with radionuclides are particularly important since they provide leaching mechanisms from disposal sites. The central theme to this research is the interaction of heavy metal actinide analogues with humic materials. Studies described focus on selected aspects of the characteristics and properties of humic substances. Some novel approaches to experiments and data analysis are pursued. Several humic substances are studied; all but one are humic acids, and those used most extensively were obtained commercially. Some routine characterisation techniques are applied to samples in the first instance. Humic substances are coloured, but their ultra-violet and visible absorption spectra are featureless. Yet, they fluoresce over a wide range of wavelengths. Enhanced fluorescence in the presence of luminescent europium(III) ions is explained by energy transfer from irradiated humic acid to the metal ion in a photophysical model. Nuclear magnetic resonance spectroscopy is applied to the study of humic acids and their complexes with heavy metals. Proton and carbon-13 NMR provides some structural and functionality information; Paramagnetic lanthanide ions affect these spectra. Some heavy metals are studied as NMR nuclei, but measurements are restricted by their sensitivity. A humic acid is fractionated yielding a broad molecular weight distribution. Electrophoretic mobilities and particle radii determined by Laser Doppler Electrophoretic Light Scattering are sensitive to the conditions of the supporting media, and the concentration and particle size distribution of humic substances. In potentiometric titrations of humate dispersions, the organic matter responds slowly and the mineral acid addition is buffered. Proton concentration data is modelled and a mechanism is proposed involving two key stages, both resulting in proton release after some conformational changes.

Post-vernacular language use in a Low German linguistic community

In a time of rapid shift and loss of smaller, regional and minority languages it becomes apparent that many of them continue to play a role as post-vernacular varieties. As Shandler (2006) points out for Yiddish in the United States, some languages serve the purpose of identity-building within a community even after they have ceased to be used as a vernacular for daily communication. This occurs according to Shandler through a number of cultural practices, such as amateur theatre, music and folklore, translation, attempts to learn the language in evening classes, etc. This paper will demonstrate that the paradigm developed by Shandler for Yiddish can be applied to other linguistic communities, by comparing the post-vernacular use of Yiddish with Low German in Northern Germany. It will focus on the linguistic strategies that individuals or groups of speakers apply in order to participate in a post-vernacular language community.