PARENT SESSION

1D - Soil and Sediment Contamination
Hall 9
8:30 AM - 12:30 PM, Tuesday, 29 April 2003
Chair: Van Noort, P.¹, ¹
Co-chair: Gerhardt, A.², ²

(TU9/1) Pollutant loads and particle structure in sediments: FTIR-DRIFT as an all-round tool for bulk particle characterization?

Gallé, Tom ^{1, 2}, Kurtenbach, Andreas², van Lagen, Barend³, ¹ Resource Centre for Environmental Technologies, Esch/Alzette, Luxembourg, Luxembourg² Dept. of Hydrology University of Trier, Trier, Germany, Germany³ Laboratory of Soil Science and Geology Wageningen University, Wageningen, The Netherlands, The Netherlands

ABSTRACT- Hydrological regime and life-cycle situations have a strong impact on the structure of river particles, both in sediments and (re-)suspended. The variation of organic and mineralogical composition causes differences in pollutant affinities and ultimately, through ingestion and digestibility of the constituents, affects the bioavailability of the transported pollutants. Hence, there is a need for a swift characterization technique that covers both mineral and organic structures and is able to be performed at low sample volumes and costs. Diffuse reflection FTIR seemed a good candidate and we tested this method on weekly collected sediments in a mid-mountain stream over a period of two years. Dealing with mixtures of mineral and organic material (living and non-living) requires statistical methods to gain maximum information out of the spectra. Two strategies have been adopted: A first approach allows a classification of sediments via a cluster analysis of the first derivatives of selected regions of the FTIR-spectra that are chosen respective of their organic or mineralogical character. Patterns of seasonal and hydrological influence could be extracted from the data enabling further interpretation of particle and associated pollutant sources. A second step consisted in testing the consistency of specific bands of the spectra by running cross-correlation among the normalized peak-heights/integrals themselves and with external parameters like org. C, C/N-ratio, particle-size distributions as well as selected metals. Finally, Py-GC-MS has been applied as a complementary structural investigation method to selected samples of the FTIR derived clusters . Potential and limitations of FTIR to characterize structural variations in mineral and organic constituents of the particles will be discussed.

Key words: particles, FTIR, mineral, organic