IEGAS
Grain Size Inter-calibration
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Results of the 1st Inter-calibration Exercise for Grain Size Analyses in Sediments (1st IEGAS) |
1. Introduction
Grain-size and grain-size distribution are among the key factors in sedimentology and landscape evolution, despite common standards have not yet been set up by the scientific community.
These parameters determine the mechanical properties of sediments and provide information on the origin and history of the landscape evolution.
The problem of comparing grain-size analyses based on different techniques and physical principles has been discussed by several authors. Because of the differences in results, many comparative studies of grain-size techniques have been carried out over the last two decades.
Depending on the type of instruments used for grain size analysis sediments can be classified in different textural classes based on the sand/silt/clay ratios.
What is the scope of the Intercalibration Exercise?
- Involvement of analytical laboratories of Research Centres, Universities, Public Associations and Private Company to develop an international network;
- Analyses of real sediments samples (gulf, lagoon and coastal) with different grain size and mineralogical characteristics;
- Comparison of grain size data determined by different instruments, analytical methods and laboratories.
2. Participating laboratories
38 laboratories from all around the world participated at the 1st IEGAS Exercise. Among them, 42% were Universities, 23% were Public Research Bodies, 18% were Environmental Protection Agencies and 15% were Private Companies.
The figure below show a general description of IEGAS participating laboratories.
3. Description of the IEGAS Intercalibration Exercise
3.1 Description of EXERCISE 1
Exercise 1 is addressed to scientists and technicians focused on the wide use of grain size determinations in environmental studies.
For Exercise 1 three sediment samples with different grain size and mineralogical characteristics have been analysed by the Reference Laboratory (RL; a, b). Then, samples have been sent by RL to the laboratories involved in the Intercalibration Exercise to be analyzed with their methodological protocols and instruments (c). Finally, analytical results have been collected by the RL and will be discussed in a final report (d).
3.2. Description of EXERCISE 2
Exercise 2 is addressed to scientists and technicians focused on sedimentological studies. For Exercise 2 three sediment samples collected in different sites with different mineralogical characteristics and different sand/clay/silt percentages have been sent by RL to laboratories involved in the Intercalibration Exercise to be sieved at different grain size and analyzed with different methods.
Finally, analytical results have been collected by the RL and will be discussed in a final report.
3.3. IEGAS sample sites
All samples were natural samples and were collected in three coastal marine areas in order to obtain different mineralogical matrix and different textures.
The figure below show the location of IEGAS sampling sites.
- S1 = Gulf of Oristano
- S2 = Lagoon of Venice
- S3= Adriatic Sea (Cesenatico)