Lakhasly

For sediment and soil samples, they were digested in a closed poly-tetrafluoroethylene system with an acid mixture of HNO3 (5 mL)-HF (1 mL)-HClO4 (1 mL) at 180 ?C for 10 h (Huang et al. 2015).The total concentrations of Cd, Cu, Ni, Pb, Cr, Zn, Fe, and Al in the digestion solutions were then analyzed by an inductively coupled plasma-atomic emission spectroscopy (ICPAES; IRIS Intrepid II XSP, Thermo Electron, USA).Because the source discrimination power of Pb stable isotopes is mainly due to 206Pb, 207Pb, and 208Pb (Sangster et al. 2000), they were measured for sediment, soil, and anthropogenic source samples by an inductively coupled plasma-mass spectrometry (ICP-MS; Agilent 7500, Agilent Technologies, USA).The relative standard deviations for duplicate samples were generally lower than 1%..

For sediment and soil samples, they were digested in a closed poly-tetrafluoroethylene system with an acid mixture of HNO3 (5 mL)–HF (1 mL)–HClO4 (1 mL) at 180 °C for 10 h (Huang et al. 2015). The total concentrations of Cd, Cu, Ni, Pb, Cr, Zn, Fe, and Al in the digestion solutions were then analyzed by an inductively coupled plasma-atomic emission spectroscopy (ICPAES; IRIS Intrepid II XSP, Thermo Electron, USA). A multi-element standard solution (GSB04-1767-2004, Guobiao Testing & Certification Co., Ltd., China) was used to establish calibration curves. For quality control, each digestion batch included 2 reagent blanks, 1 standard reference material, and 1 duplicate sample to assess the accuracy and precision of the measurements. Replicate analysis of the standard reference material GBW-07304 (National Research Center for Geo analysis, China) showed good accuracy, with overall recovery rates ranging from 97 to 106%. The relative standard deviations for duplicate samples were less than 5%. The method detection limits, defined as 3 times the standard deviation of blank measurements, were 0.1, 0.4, 0.4, 1.4, 0.5, 1.2, 8.9, and 8.9 mg/L for Cd, Cu, Ni, Pb, Cr, Zn, Fe, and Al, respectively.
Because the source discrimination power of Pb stable isotopes is mainly due to 206Pb, 207Pb, and 208Pb (Sangster et al. 2000), they were measured for sediment, soil, and anthropogenic source samples by an inductively coupled plasma-mass spectrometry (ICP-MS; Agilent 7500, Agilent Technologies, USA). During ICP-MS measurement, the peak pattern of maximum (20 points) was chosen, and the integration time was set as 0.3 s (Luo et al. 2015). To optimize the analytical performance, the digestion solutions above were diluted with 5% HNO3 to approximately 20 μg/L according to total Pb concentration (Margui et al. 2006). The method detection limits were 0.06, 0.07, and 0.07 μg/L for 206Pb,
207 208
Pb, and Pb, respectively. The relative standard deviations for duplicate samples were generally lower than 1%. In addition, solutions of the standard reference material NIST 981 (National Institute of Standards and Technology, USA) were measured after every 5 samples for calibration and quality control. The average measured ratios of 206Pb/207Pb and 208Pb/207Pb for the standard reference material were 1.091 and 2.371, which were generally in good agreement with the certified values of 1.093 and 2.370, respectively.
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