Changes in Spectral Slope due to the Effect of Grain Size and Moisture in Beach Sand of Western Puerto Rico

A GER-1500 spectroradiometer was used to collected reflectance measurements in several laboratory experiments using sand from five beaches of western Puerto Rico. Sand samples were analyzed and the spectral slope was calculated to determine its changes due to different grain size and composition. Results indicate that all the studied parameters of sand (grain size, composition and humidity) affect the magnitude of the reflectance and the spectral slope. The reflectance curve showed the major change between 450 and 550 nanometers in all the five beaches. Higher magnitude in the slope correlates with fine grain size and carbonates composition material and lower magnitudes in the slope with bigger grain size and higher composition of dark minerals. It was also found that the spectral are reduced with an increase in the water content. The statistical analyses of the spectral slope show that they have significance difference between the different grain sizes.