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Nitrate is the main contaminant of excessive nitrogen in surface water. Accurate identification and analysis of different source's contribution rates is the key to source control of nitrate pollution. Based on the stable isotopes of nitrogen and oxygen in nitrate and Bayesian mixing model, nitrate transformation processes, proportions of source contributions and the corresponding uncertainty are studied in waters of Xiannyu Lake, Xinyu City. The results show that NO3--N was the primary form of nitrogen in waters of the lake, with its proportion exceeding 60%. Assimilation of phytoplankton existed in the surface waters while nitrification dominated the nitrogen cycling. The main nitrate source was manure/sewage, the proportional contribution of which is 59.4%, and then followed by nitrogen fertilizer (20.7%), soil organic nitrogen (17.3%) and atmospheric deposition (2.6%). The proportional contributions of soil organic nitrogen and fertilizer sources showed the highest uncertainty, and the uncertainty would increase significantly when ignoring the fractionation effect of nitrification. [ABSTRACT FROM AUTHOR]

ABSTRACT The electrochemiluminescence (ECL) behavior of luminol on a nafion-nano-TiO2 modified glassy carbon electrode (nafion-nano-TiO2GCE) was studied. Two ECL peaks (ECL-1 and ECL-2) were found during cathodic potential scanning. ECL-1 at ca −0.4 V (vs AgAgCl reference electrode) came from the reaction between luminol and active oxygen anion produced at the GCE surface directly, while ECL-2 at ca −0.9 V (vs AgAgCl reference electrode) came from the reaction between luminol and the active oxygen anion catalyzed by TiO2. The possible mechanism for the generation of both ECL peaks has been proposed. The reproducibility of the ECL intensities on nafion-nano-TiO2GCE at ECL-1 and ECL-2 was good, with relative standard deviations ( n = 10) of 4.3 and 1.3%, respectively. The ECL-2 generated at the nafion-nano-TiO2GCE surface was further developed to detect the dissolved oxygen, and a detection limit of 0.02 mg/L was achieved. The proposed method was applied to detect dissolved oxygen in water with satisfactory result. Copyright © 2010 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The electrochemiluminescence (ECL) behavior of luminol on a nafion-nano-TiO(2) modified glassy carbon electrode (nafion-nano-TiO(2)--GCE) was studied. Two ECL peaks (ECL-1 and ECL-2) were found during cathodic potential scanning. ECL-1 at ca -0.4 V (vs Ag--AgCl reference electrode) came from the reaction between luminol and active oxygen anion produced at the GCE surface directly, while ECL-2 at ca -0.9 V (vs Ag--AgCl reference electrode) came from the reaction between luminol and the active oxygen anion catalyzed by TiO(2.) The possible mechanism for the generation of both ECL peaks has been proposed. The reproducibility of the ECL intensities on nafion-nano-TiO(2)--GCE at ECL-1 and ECL-2 was good, with relative standard deviations (n = 10) of 4.3 and 1.3%, respectively. The ECL-2 generated at the nafion-nano-TiO(2)--GCE surface was further developed to detect the dissolved oxygen, and a detection limit of 0.02 mg/L was achieved. The proposed method was applied to detect dissolved oxygen in water with satisfactory result., (Copyright © 2010 John Wiley & Sons, Ltd.)