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 Jia‡Di Xu†Qin Sun‡Lei Zhang†Chengxin Fan†Chaosheng Zhang§