Use of soil color meter for aqueous iron and ammonium measurements(Environment)

概要

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In this paper, we proposed a new approach for on-site colorimetric analysis of ferrous ions (Fe^<2+>) and ammonium-nitrogen (NH_4^+-N) using a soil color meter as an alternative method to conventional spectrophotometry. The soil color meter we used can express solution color numerically on the basis of L^*a^*b^* color space. After coloring of water by the 1,10 phenanthroline method and the Indophenol blue method, the color of solution was measured by the soil color meter. A linear relationship between Fe^<2+> and a^* or b^* values, and systematic change of NH_4^+-N with L^* value, enable us to make a calibration curve. The Fe^<2+> and NH_4^+-N concentrations in groundwater samples (Fe^<2+>: 0.3-1.3 mg L^<-1>; NH_4^+-N: 0.02-0.62 mg L^<-1>) determined by the proposed method agreed well with those determined by conventional spectrophotometry with the difference being ± 0.05 mg L^<-1> and ± 0.02 mg L^<-1>, respectively. Since a similar apparatus is widely used in the soil science field, this technique would facilitate field surveys.
一般社団法人日本土壌肥料学会の論文