An investigation of grain size, organic compounds and metal distribution in 23 sediment samples of the Geum-River basin (Korea) was conducted in two seasons of 2012 (dry season and rainy season). The samples of sediment were collected from the basin and investigated for concentrations of some metal and general indexes containing grain size. Concentrations of Pb, Zn, Cu, Cr, Ni, As, Cd, Hg, Al and Li have been determined by inductively coupled plasma spectrometer (ICP) and the sediments organic matter content was determined by the loss on ignition, and sediments were fractionated with three different nylon sieves. Correlation analysis was made for grain size, organic material and metal concentrations, and the Pearson correlation coefficients between their concentrations were determined. As a result, the higher metal concentrations were found in the period of the dry season than in another season. The metal concentrations showed high correlation with that of organic material (COD and TOC). Thereby, the high distribution of metal concentrations in sediment containing high organic compound is suggesting an interaction with organic matter.
In this study, we developed a rapid and simple analytical method for the simultaneous determination of pesticide residue in environmental water using an LC-Orbitrap (Q-Exactive Plus) with electrospray ionization mode. The detection process was performed in Full scan/ddMS2 mode. Sample preparation was performed using online SPE. Only 1 mL of each water sample was injected during the on-line SPE and the samples were concentrated in a Hypersil GOLD aQ trapping column. We compared seven gradient programs and three analytical columns to analyze the 360 pesticides. Most compounds were detected using the CORTECS C18 column with the 7 th gradient program method. The established method was validated by linearities, accuracy, precisions, and limits of quantification (LOQ) of the 340 pesticides. The calibration linearities were over 0.994 and LOQ were 5.2-283.3 ng/L. Accuracy and precision values were achieved in the ranges of 91-120% and 0.63-8.21%, respectively. This method can be applied to effectively monitor the health of aquatic environments and can be potentially applicable in a variety of fields in the future.
BACKGROUND:Recently, the project for improvement
Introduction The principle oxidants in the drinking system are dissolved oxygen and chlorine, and the corrosion of water pipe is going alone because of oxidants reaction. Since 1930, pH control chemicals such as NaOH, Ca(OH)2, NaHCO3, and phosphate corrosion inhibitors have been used to prevent the corrosion of water pipes. However, to directly add Ca(OH)2at inlet of water well in production process of drinking water may cause a problem to make clouding phenomenon in tap water. The objective of this study removes such problems as the turbidity, strengthen more safety of water. Experimental Materials – The iron(carbon steel) was in the form of sheet 0.04 cm in thick and the following analysis: Fe 99.62%, Mn 0.26%, Cu 0.08%, Ni 0.05%, Mo 0.01%. specimens cut from this sheet measured 15cm×1.2cm. The chemicals used as corrosion inhibitors were NaOH, Ca(OH)2, and H3PO4 and tap water used as blank. NaOCl was used to disinfect the drinking water made by the demo plant. In order to examine the effect of disinfectant residual concentration according to adding lime water and corrosion inhibitor such as ortho phosphate(H3PO4), the residual concentration of disinfectant was measured in carbon steel water pipe 50 m in length at the corrosion pilot plant and the temperature of solution was in room temperature between 5°C in the winter to 35°C in the summer. Chlorine residual concentration in the water pipes 50 m in length was measured for 5, 10, 20, 40, 60 min, respectively. The electrochemical tests was measured using Solartron Potentiostat 1480 and the test was performed in a typical three electrode cell which consist of carbon steel as working electrode, saturated calomel electrode as reference electrode, platinum counter electrode. Result s HOCl and OCl- in drinking water which chlorine was added as disinfectant reach in equilibrium state at nearly pH 7.5. As pH increases, more of OCl- exists than the strong disinfectant, HOCl-, Increasing HOCl below pH 7.5 is more benefit in terms disinfectant efficiency. Figure 2 above shows the concentration of free residual chlorine with time. Running drinking water in the pipe, adding PO4 decreased concentration of chlorine from 0.48 to 0.28 ppm for 40 min, NaOH decreased concentration of chlorine from 0.45 to 0.10ppm, Ca(OH)2 decreased concentration of chlorine from 0.24 to 0.10 ppm, but tap water as blank degreased concentration of chlorine from 0.40 to 0.07 ppm for only 10 minutes. Of three corrosion inhibitors, PO4 showed the highest reduced efficiency for the concentration of residual chlorine. To inhibit the reaction of chlorine with metal water pipe is similar to inhibit the corrosion reaction. Reference US EPA, Disinfection Profiling and Benchmarking, EPA Guidance Manual, August 1999. American Society for Testing and Materials, G 4-95(1996). Figure 1
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