Soil spectroscopy as a method to monitor Total Petroleum Hydrocarbon (TPH) contamination in soil

Contamination of soil with Petroleum hydrocarbons plays an important role in recent environmental deterioration. The commonly used analytic method for assessing Total Petroleum Hydrocarbons (TPH) in soil samples, is based on extraction with 1, 1, 2-Trichlorotrifluoroethane (Freon 113), a substance prohibited to use by the EPA. The current paper assembles the use of reflectance radiation across the VNIR-SWIR region (400-2500 nm) to monitor TPH concentration in soil. This technology is environmental friendly and permits rapid and cost-effective measurements of large number of samples. Artificial contaminated samples were analyzed chemically and spectrally to form a database of 5 soils contaminated with 3 types of TPH, creating 15 datasets of 48 samples each at contamination levels of 50–5000 wt% ppm. A brute force preprocessing approach was used by combining 8 different preprocessing techniques at “all possibilities”, resulting in 120 different mutations for each dataset. The brute force was done based on an innovative computing system developed for this study termed “all possibilities” approach. The use of the “all possibilities” system proved to be effective and efficient for optimal spectral modeling in soil in general and assessing TPH contamination in soil in particular.