High-Resolution, Two-Dimensional Measurement of Dissolved Reactive Phosphorus in Sediments Using the Diffusive Gradients in Thin Films Technique in Combination with a Routine Procedure

May 30, 2020

ABSTRACT: Dissolved reactive phosphorus (DRP) is the most available P form insedimentsandoftendirectlycontrolsphytoplanktonbloomsinaquaticsystems. In this study, a novel procedure was developed for two-dimensional (2D) measurement of DRP in sediments at a spatial resolution of 0.45 mm using the diffusive gradients in thin films (DGT) technique with a revised high-capacity binding phase (Zr oxide gel). This procedure involves DGT uptake of P in sediments, 2Dslicing ofthebindinggelona0.450.45-mmgridsystem,elution ofPfromeachgelsquarewith1MNaOH,andmicrocolorimetricdeterminationof DRPineachelutedsolutionusing384-microwellplates.MeasurementsofDRPvia thisprocedureweretestedinhomogeneoussolutionsandsedimentsandproduced an acceptable error (<20% relative standard deviation) for the analysis once the accumulated mass of P in each gel square reached 1.2 μg cm2. This method was successfully applied to produce 2D images of the DRP distribution in sediments with and without the influence of tubificid worm bioturbation, revealing a much more pronounced and localized impact from tubificid worms than that found using a one-dimensional measurement of pore water DRP concentrations at 1-cm resolution.


Writers: Shiming Ding*†Fei JiaDi XuQin SunLei ZhangChengxin FanChaosheng Zhang§