Browsing by Author "Järvinen, Juha"

Petroleum hydrocarbons (PHCs) and heavy metals are common soil contaminants, which when released in the environment have the potential to damage plants as well as endanger the health of both humans and animals. Investigating these contaminations for cleanup purposes is therefore important, and developing new rapid techniques to aid in this process would be beneficial. VNIR-SWIR (350–2500 nm) reflectance spectroscopy is a well-known method that has been shown to be a promising tool for the rapid and costeffective mapping and monitoring of various soil contaminations. However, previous studies have mainly focused on the spectral features of soil contaminants; the anisotropic nature of reflectance and polarization have been largely ignored. Characterization of these reflectance properties has the potential to provide valuable additional information, that can be used to improve remote-sensing methods and help develop reflectance models for the quantitative and qualitative analysis of contaminants in soil. To study the bidirectional reflectance and polarization properties of petroleum hydrocarbons and lead, the Finnish Geodetic Institute Field Goniospectrometer (FIGIFIGO) was used to measure samples artificially contaminated with diesel, motor oil and lead in the laboratory as well as lead contaminated soil and vegetation at Suomenlinna, Finland. In total, 23 samples were measured. It was confirmed that petroleum hydrocarbons can be detected from their characteristic absorption bands, and that the 1730 nm band is the most significant for this purpose. However, clay minerals appeared to considerably lower the intensity of these bands and affect the reflectance. Despite this, hydrocarbon absorption features were successfully detected from all samples at a lowest measured concentration of 0.5 wt.%. The polarization in the backward direction was found to decrease when diesel or motor oil was added, while the polarization increased in the forward direction on low zenith angles. In order to better understand the relationships between clay, water, hydrocarbon and quartz contents and their combined effects on the reflectance, more studies are needed. The reflectance and polarization of the laboratory Pb samples were found to increase significantly in the forward direction, while the polarization decreased in the backward direction in the SWIR region. This characteristic, if investigated further, could prove useful for the detection of heavy metals in soil. Lead was not reliably detected from the field samples, but more controlled studies on the relationship between soil contaminations and polarization properties of vegetation should be considered.