This study introduces the use of infrared camera for finding, detecting and evaluating contaminated sites. In recent years, our research team has introduced an innovative use of aerial thermography to detect several illegal activities, as illicit landfills, unauthorized sewage and other “anomalies” on the surface waters, identified by their thermal infrared signatures . This paper introduces first results of a Thermal approach, based on radiometric data used to identify different pollutants in soil matrix and its role in environmental surveys. The method adopted in this study has been developed for the main pollutants verified in the chemical analysis for land, reproduced according to the law and a laboratory task as well. The method has been developed to individualize the presence of pollutants in the soil. It’s well known how the landfill management is intricate, particularly after the capping stage, when it’s fundamental the detection of the pollutants diffusion in the surrounding area. Moreover, the problem of illegal landfills is nowdays topical, and there is a great exigency of identifying this critical areas. The traditional methods used for checking the soil that have been polluted consist in collecting samples of land, afterwards analyzed in chemical laboratories. This kind of analyses requires a great amount of resources such as time and money, even though in most cases is compulsery to know as soon as possible the conditions of the site. It is clear that the need of a new technology is increasingly felt. The latest advanced technology available today are remote and proximal sensing, in which the thermography plays a fundamental role. This technique is used for detecting anomalies in various sectors such as construction, renewable energy and electric systems. Previous studies demonstrate that thermography can be applied to point out pollution in rivers and sea . The application of the thermography we bear in this work is the ﬁrst known for revealing contamination in lands. The indirect method here used could help in providing evidence of contamination in big areas where the state is unknown. In this case, the use of traditional laboratory techniques would be applied only when the thermographic technique reveals anomalies. The scope of this work is to: • catalog the pollutants in liquid form, according to different emissivity value of each one considered in this study; • appreciate the signatures of the pollutants and their aspect through radiometric data, after the scattering in soils samples. The indirect method has been used in this study for apprising the presence of pollutants, chosen as required by law, using their thermal signature detected by an IR thermal sensor. The anomalies have been identified using the thermal IR signatures of the different materials by an infrared camera which thermal sensitivity is 30 mK , and has got a 640x480 IR detector, that gives the temperature in every point of the acquired image (each pixel corresponds to a value of temperature or emissivity that is stored in a data matrix). The accuracy is really high (1%) and 3.2-megapixel visible light camera. The Focal Plane Array (FPA) is an uncooled microbolometer, and the output data are radiometric. For the first step have been considered pollutants for soil in known concentration made in laboratory, selected within the most those typically are present in the soil matrix, in order to set up the most close conditions to those which can occur in the fields during a monitoring action in a wide area. The selected pollutants belong to different chemical families: heavy metals (antimony, cobalt, lead, nickel, zinc), hydrocarbons (gasoline, diesel), oils (motoroil, extra virgin olive oil). The results obtained are satisfactory, infact it has been possible to distinguish and classified almost 8 different classes of compounds but there is still a room for improvement in order to identify a larger number of classes. For the second step were prepared land sample type of soil in different aliquots, each one doped, by rain or spot, sprinkled with solutions of known concentration of individual and different contaminants, appropriately selected and dissolved in an appropriate solvent. The results of this test are interesting as well, because the thermal differences between the clean soil and contaminated ones are detectable, also between soil dropped with different pollutants. These odds are noticeable not only by graphical view, but also comparing the emissivity values of the samples .
|Titolo:||A new application of the infrared thermography: finding illicit landfills and contaminated soils|
|Autori interni:||LEGA, MASSIMILIANO|
|Data di pubblicazione:||2015|
|Appare nelle tipologie:||4.1 Contributo in Atti di convegno|