Feasibility of Using Near-Infrared Spectroscopy for Rapid Quantification of 17β-Estradiol Sorption Coefficients in Soil

Livestock manure contains natural steroid hormones, with the most potent being 17 beta-estradiol. The transport of steroid hormones from agricultural fields to adjacent water bodies can result in 17 beta-estradiol environmental contamination impacting aquatic organisms. Sorption coefficients are useful input into models that estimate risk of water contamination. The feasibility of applying near-infrared spectroscopy (NIRS) for determining sorption coefficients of 17 beta-estradiol in soil was investigated for two irregular undulating to hummocky terrain landscapes in Manitoba and Saskatchewan, Canada. A total of 609 soil samples in 140 soil profiles were collected from several horizons to a depth of 1 m. Air-dried and sieved (2 mm) soil samples were analyzed for soil organic carbon (SOC), soil pH, and soil texture. Sorption coefficients of 17 beta-estradiol were determined by a batch equilibrium process. Spectral data were collected from soil samples (25 g) using two instruments, the 45VISNIR Zeiss Corona (wavelength range 700-1690 nm) and the Foss NIRSystems 6500 (wavelength range 1100-2500 nm). Regardless of the site and instrument, the predictive models were excellent for both SOC and 17 beta-estradiol sorption coefficients. The data thus generated can be used as input parameters in fate models for efficient risk assessments and decision-making programs for environmental safety where soils are at risk of receiving inputs of 17 beta-estradiol. Calibration results for soil pH were also adequate with Corona outperforming the Foss instrument. Soil texture predictions were relatively unsuccessful regardless of the instrument and site.