Laser-induced breakdown spectroscopy for environmental monitoring of soil carbon and nitrogen

Carbon reservoirs at the earth's surface comprise the plant and microbial, biomass, and organic and inorganic carbon in soils, lakes, rivers, and oceans. These reservoirs interact with the atmosphere and affect its CO₂ content. Soil organic carbon (SOC) is an essential constituent in all ecosystems that can be enhanced by manipulating agricultural and forest lands. A successful strategy is the determination of the amount (quantity) and the chemical composition (quality) of carbon and nitrogen stored within the soil profile. The need for rapid analysis of both the soil quantity and quality is an essential part of determining the techniques of choice for measuring SOC. We have successfully demonstrated the technique of laser-induced breakdown spectroscopy (LIBS) in the determination of the total concentration of carbon and nitrogen in soils and have also been successful in the development of electrochemical-surface enhanced Raman spectroscopy (Electro-SERS), the results for which will be reported in another article. In this article we will focus on the data obtained using the LIBS technique. Our preliminary results suggest that LIBS method can be used for developing a field deployable instrument that can be used for in situ, real time monitoring of total carbon and nitrogen in soil. We have determined the total concentration of carbon in 15 soil samples and have obtained a calibration curve for them.