Exploiting flow analysis as a tool for monitoring the leaching process of micronutrients using laboratory scale soil columns (LSSCs)

Monitoring the soil/water interface has become fundamental for both environmental and agricultural studies. This work aimed to set up and monitor laboratory scale soil columns (LSSCs) for assessing nutrient levels and characterizing soil leachates using flow analysis methods. A flow analysis method was developed to determine calcium and magnesium concentrations, overcoming the disadvantages of conventional methods in terms of time consumption, waste production and cost. The LSSCs were set up with soil cores from distinct locations and with burned soil to verify if soil type or forest fires affect leaching behaviour. Leachates were obtained through rain simulations with rainwater. In order to establish valid comparisons, simulated rain was assessed before and after going through the LSSCs. The accommodation of both metals in the same sequential injection manifold was successfully attained, as well as the determination of ranges of calcium of 0.160-35.0 mg L^-1, and a range of magnesium of 0.160-8.00 mg L^-1. The developed method was successfully used to monitor different soil leachates, allowing for the assessment of both metal ions before and after going through the LSSCs. The limits of detection obtained for calcium and magnesium determinations were 7 and 8 μg L^-1, respectively. Effluent production equalled 1.8 mL for the assessment of magnesium and the smaller range of calcium and 2.0 mL for the larger range.