engleski

Complementary methods for characterization of stream sediments as an aid in assessment of sediment quality

Introduction The European water framework directive (WFD) has not come yet up with environmental quality standards for sediments. It is still open which sediment monitoring approaches will be used. The aim of the present work is to demonstrate on selected stream sediments what type of characterization can be obtained when using interdisciplinary approach. Methods Complementary methods were: X-ray diffraction (XRD), inductive coupled plasma &#8211; mass spectroscopy (ICP-MS), Xray fluorescence (XRF), solid state 27Al MAS NMR, 29Si MAS NMR, grain size analysis and Mössbauer spectroscopy. Results, discussion and conclusion Advantages and disadvantages of each method were discussed. Solely ICP-MS method requires chemical decomposition. It is the most useful for microelement analysis (51 element), which data can be used in geostatistical analysis and detection of anomalies. Other techniques are non destructive and require simple physical sample preparation. XRD method can give with certainty class and group of minerals. Determination of clay minerals, when present <5%, is less certain. XRF method is suitable for determination of major elements, particularly of Si and limited number of trace elements. However, Mg and Na cannot be detected. The particle size distribution was determined in fraction <63 &#181; ; m. It was found that the amount of clays (fraction <4 &#181; ; m) was in the range 7.4 &#8211; 12.6%. Mössbauer spectra taken at room temperature and at 70 K in a mixture of several minerals are difficult to interpret. Valuable information concerning the valence and site populations of iron in poorly crystallized minerals can be obtained. Solid state 29Si MAS NMR can give structural information, like the number of different SiO4, Si(Al)O3 units. 27Al MAS NMR gives the presence and number of tetrahedral and octahedral Al sites and their ratio. Grain size analysis and surface area of particles is a fundamental property of sediments and is important in pollution research. All of the studied methods are recommended in future sediment analysis.

stream sediments; monitoring; WFD; complementary methods

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