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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]

To promote the resource utilization of steel slag and improve the production process of steel slag in steelmaking plants, this research studied the characteristics of three different processed steel slags from four steelmaking plants. The physical and mechanical characteristics and volume stability of steel slags were analyzed through density, water absorption, and expansion tests. The main mineral phases, morphological characteristics, and thermal stability of the original steel slag and the steel slag after the expansion test are analyzed with X-ray diffractometer (XRD), scanning electron microscope (SEM), and thermogravimetric analysis (TG) tests. The results show that the composition of steel slag produced by different processes is similar. The main active substances of other processed steel slags are dicalcium silicate (C2S), tricalcium silicate (C3S), CaO, and MgO. After the expansion test, the main chemical products of steel slag are CaCO3, MgCO3, and calcium silicate hydrate (C-S-H). Noticeable mineral crystals appeared on the surface of the steel slag after the expansion test, presenting tetrahedral or cigar-like protrusions. The drum slag had the highest density and water stability. The drum slag had the lowest porosity and the densest microstructure surface, compared with steel slags that other methods produce. The thermal stability of steel slag treated by the hot splashing method was relatively higher than that of steel slag treated by the other two methods. [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.)