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OBJECTIVES@#To establish a diatom database by analyzing the quatity, species distribution and differences of diatom in water samples of the whole navigable sections of the Beijing-Hangzhou Grand Canal, to provide a reference for the inference of the drowning site.@*METHODS@#Water samples were collected at 22 sites in the navigable sections of the Beijing-Hangzhou Grand Canal (Jining section to Yangzhou Section), and the diatoms at each site were qualitatively and quantitatively analyzed by using graphite digestion-scanning electron microscopy.@*RESULTS@#Sampling site T (Laohuaijiang River Line, Gaoyou City, Yangzhou City, Jiangsu Province) had the highest number of diatoms, while sampling site O (Siyang County, Suqian City, Jiangsu Province) had the lowest number of diatoms, with a large gap of 68 times. At sampling site Q (Jiangpu District, Huaian city, Jiangsu Province), there were 19 species of diatoms. The sampling site O had the least diatoms, with 7 species. There were no significant differences in species evenness and species diversity at each sampling site (P>0.05). Some sampling sites have characterized diatoms, such as Caloneis at station A (Taibai Lake, Weishan County, Shandong Province), Rhoicosphenia at station B (Nanyang Town, Weishan County, Shandong Province), Amphora at station I (Taierzhuang District, Zaozhuang City, Shandong Province) and Epithemia at station J (Pizhou 310 national highway, Xuzhou City, Jiangsu Province).@*CONCLUSIONS@#The species richness of diatoms gradually increased from north to south. Diatom species richness and species diversity might be higher in areas with complex environments and large population flow. Climate type has a certain influence on the distribution of diatoms.
Subject(s)
Humans , Beijing , Diatoms , Drowning , Rivers , WaterABSTRACT
Objective To establish and evaluate a method for determination of total arsenic in urine by test-tube rapid digestion hydride generation atomic fluorescence spectrometry.Methods After digestion of urine samples using graduated test-tube and graphite digestion apparatus,arsenic content in urine was determined with atomic fluorescence spectrometer.Then the test results were evaluated by using quality control measures,such as precision and accuracy experiments,and the results between different laboratories were reviewed and compared.Results The urinary arsenic was in a linear range of 0-0.300 mg/L,correlation coefficient (r) ＞ 0.999 3,detection limit was 0.000 21 mg/L,relative standard deviation (RSD) ≤4.62％ and the recoveries of standard addition were 93.9％-104.3％.The value of standard reference material measured was within the allowable range.The blind sample of the national urinary arsenic was qualified.Conclusions This method is suitable for large scale determination of urinary arsenic for its micro sample amount needed,less interference and strong practicability.The error results are in a controlled range.
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OBJECTIVE: To establish a method for determination of urinary tin by atomic fluorescence spectrophotometry.METHODS: The graphite digestion instrument was used to digest 2. 50 m L urinary sample with 1. 50 m L concentrated nitric acid,hydrochloric acid( volume fraction 4. 00%) was added to a total constant volume of 10. 00 m L. After 2. 50 m L of thiocarbamide-ascorbic acid( mass concentration 100 g / L) was added,hydrochloric acid( volume fraction 4. 00%) was added to a total constant volume of 25. 00 m L( equivalent to urinary sample was diluted 10 times),1. 00 m L of the sample was collected and detected by atomic fluorescence spectrophotometry. RESULTS: The good linear relationship was shown in the range of 4. 00-200. 00 μg / L with a correlation coefficient of 0. 999 5. The limit of detection was 0. 20 μg / L. The recovery rates ranged from 100. 20% to 100. 84%. The within-run relative standard deviation( RSD) and between-run RSD were 0. 11%-2. 01% and 1. 37%-5. 58%,respectively. The samples can be stored for 7 days under the temperature of4 ℃. CONCLUSION: This method has the advantages of high sensitivity,precision and convenient operation,which is suitable for the daily determination of urinary tin in human.