Regolith properties under trees and the biomechanical effects caused by tree root systems as recognized by electrical resistivity tomography (ERT)

In the Middle Ages, trade and craft started developing intensely in Krakow, a significant metropolis of Central Europe. This led to a considerable demand for water, which resulted in the creation of an elaborate network of artificial watercourses. Their course, until today, has not been sufficiently studied. Non-invasive geophysical methods combined with a small diameter borehole drilling technique and geochemical analyses can identify the presence of structures connected with historical moats, millstreams, etc. on the basis of historical sediment recognition. The research carried out in 2010 involved measurements with two geophysical methods, i.e. the ground-penetrating radar (GPR) and the cesium magnetometer. Due to the high attenuation of electromagnetic waves by anthropogenic soil and magnetic disturbances connected with a tram line, additional measurements were undertaken using the electrical resistivity tomography (ERT) technique. This method allowed the detection of structures buried under anthropogenic layers. Based on the use of borehole drilling and the acquisition of ground profiles, it was possible to present a more precise interpretation. In consequence, the location of historical watercourses was determined and the course of their fragments was mapped more precisely. The measurement of the basic physicochemical proprieties of the ground samples (pH, Eh, EC) and determining the metal concentration with atomic absorption spectroscopy (AAS), enabled to identify anthropogenic-origin metals, such as Cu and Pb, and also those of the geogenic origin, like Fe, in the medium. The measured values were correlated with the measurement results of magnetic susceptibility, which allowed for lithological classification of the layers.

Historical anthropogenic layers identification by geophysical and geochemical methods in the Old Town area of Krakow (Poland)

Field Assessment in Rock Art and Cultural Stone Decay

Research conducted in a municipal park in a small town located in the Province of Silesia (southern Poland) showed that the park vegetation was growing on a Technosol, formed on highly magnetic anthropogenic material. The metallurgical waste came from the local steel mill and foundry and creates a subsoil in a significant part of the municipal park. This waste is covered with an organic layer of approximately 10 cm. Utilizing specific magnetic and geoelectrical properties of the wastes, we proposed a unique combination of integrated geophysical measuring techniques including soil magnetometry, electrical resistivity tomography (ERT) with varying unit electrode spacing, and electromagnetic profiling (EM) to assess continuity, thickness, and the depth of the anthropogenic layer of metallurgical wastes. The maximal thickness of the metallurgical wastes was identified in the western part of the studied area, and the same material was found in the eastern part of the park forming individual lenses or nests within 8 m deep zone in the area of a buried ravine where the historical railway line was located. The shallow ERT profiles (with unit electrode spacing 0.5 m) also revealed a thin layer of material with high resistivity (>500 Ωm). Thermomagnetic analyses have shown that the sources of the extremely high magnetic susceptibility of the wastes were magnetite and metallic iron (αFe). The detected high concentration of Fe and Mn was not accompanied by potentially toxic metals and, at relatively high pH values (6.5–9.0), does not constitute a significant ecological threat.

Application of different geophysical techniques to study Technosol developed on metallurgical wastes

In the present study, application of complementary to each other non-invasive geophysical methods and geochemical slim hole drilling allowed to locate a small fragment of the historical water system, and to determine the type and stratigraphy of the sediments filling it. The most universal, and frequently used geophysical methods are electrical resistivity tomography (ERT) and ground penetrating radar (GPR). These methods are characterized by high precision mapping of the investigated medium, and the possibility of implementation even in small areas. They play an important role in defining the location of archaeological excavations sites. The applied geophysical methods enabled precise and comprehensive analyses of near-surface zones in the area of Planty Park in Krakow (Poland), such as engineering/geological recognition, and detection of anthropogenic structures. As an important metropolis of Central Europe in the medieval period, Krakow due to rapid development of craft and trade had a high demand for water both for the general population and craftsmen. As a result, the city continuously developed and used a complex watercourse and sewage collection system. The layout of the system has not yet been accurately mapped. The authors decided that the ERT method was suitable for this case study. The study was conducted in the eastern part of Planty Park, near Dominikanska Street, measurements were taken using a two-dimensional (2D) parallel layout of ERT profiles. The authors also carried out a three-dimensional (3D) image interpretation process. Even though the ERT method is limited by the requirement of a minimal implementation area, it makes the detection of former watercourses possible. In order to verify the ERT results, three small-diameter mechanical holes drillings were carried for purpose of macroscopic analysis of the ground type with determination of its lithology and layer layout. On gathered samples laboratory measurements of pH, oxidation–reduction potential Eh, and conductivity EC were done. Copyright © 2016 John Wiley & Sons, Ltd.

Geophysical and Geochemical Studies on Historical Layers in the Area of Old Krakow, Poland

Planowanie badań oraz ocena skuteczności zastosowania metody tomografii elektrooporowej do monitoringu zanieczyszczeń na podstawie modelowania numerycznego

Wioleta Antonik

Papers

Geophysical and Geochemical Studies on Historical Layers in the Area of Old Krakow, Poland

Planowanie badań oraz ocena skuteczności zastosowania metody tomografii elektrooporowej do monitoringu zanieczyszczeń na podstawie modelowania numerycznego