Evaluation of water hygiene in public swimming places in Chongqing based on principal component analysis
结果 游离性余氯、浑浊度、pH、浸脚池游离性余氯、尿素、菌落总数、大肠菌群合格率分别为91.30%、89.40%、91.30%、91.30%、99.00%、95.20%、86.50%，各指标的P50值分别为0.455 mg·L−1、0.59 NTU、7.352、6.63 mg·L−1、0.78 mg·L−1、8 CFU·mL−1、0 CFU·100 mL−1。主成分分析结果显示KMO=0.573，P<0.001；共提取出4个主成分，各主成分特征值分别为2.990、1.624、0.854、0.617，其累计贡献率达86.928%。巴南区、北碚区、璧山区、丰都县、奉节县、江北区、南岸区、南川区、彭水县、黔江区、荣昌区、石柱县、潼南区、万州区、永川区、渝中区、长寿区、忠县的综合评价值依次为−0.139、0.228、0.587、0.042、−3.365、0.587、0.597、0.587、0.189、−1.127、−0.201、−0.181、0.587、0.416、0.587、0.587、−0.098、0.043。主城中心区、主城新区、渝东南片区、渝东北片区综合评价值的P50分别为0.587、0.587、−0.181、0.043。
Background At present, the evaluation of water quality in public swimming places mostly adopts the single index evaluation method, ignoring the possible correlation between the indicators, the problem of information overlap between the indicators, and the differences between the swimming places with single or multiple unqualified water quality indicators.
Objective To evaluate water quality in public swimming places in Chongqing objectively, intuitively, and comprehensively.
Methods In 2020, a stratified random sampling method was used to investigate seven water quality indicators of 112 public swimming places in the central urban area, the new downtown urban area, the northeastern area, and the southeastern area of Chongqing. The selected indicators were free residual chlorine, turbidity, pH, free residual chlorine in disinfection pool of feet, urea, total plate count, and coliform bacteria. Principal component analysis was utilized to comprehensively evaluate water quality of swimming places by calculating principal component characteristic values and comprehensive evaluation values.
Results The qualification rates of free residual chlorine, turbidity, pH, free residual chlorine in disinfection pool of feet, urea, total plate count, and coliform bacteria were 91.30%, 89.40%, 91.30%, 91.30%, 99.00%, 95.20%, and 86.50%, respectively, and the P50 values were 0.455 mg·L−1, 0.59 NTU, 7.352, 6.63 mg·L−1, 0.78 mg·L−1, 8 CFU·mL−1, and 0 CFU·100mL−1, respectively. The results of principal component analysis showed that KMO=0.573, P<0.001; four principal components were extracted, the eigenvalues of each principal component were 2.990, 1.624, 0.854, and 0.617, respectively, and the cumulative contribution rate was 86.928%. The comprehensive values of Banan District, Beibei District, Bishan District, Fengdu County, Fengjie County, Jiangbei District, Nan'an District, Nanchuan District, Pengshui County, Qianjiang District, Rongchang District, Shizhu County, Tongnan District, Wanzhou District, Yongchuan District, Yuzhong District, Changshou District, and Zhongxian County were −0.139, 0.228, 0.587, 0.042, −3.365, 0.587, 0.597, 0.587, 0.587, 0.189, −1.127, −0.201, −0.181, 0.587, 0.416, 0.587, 0.587, −0.098, and 0.043, respectively. The comprehensive evaluation values (P50) of the central urban area, the new downtown urban area, the southeastern area, and the northeastern area of Chongqing were 0.587, 0.587, −0.181, and 0.043, respectively.
Conclusion The hygienic status of water in public swimming places in Chongqing is above average in China, but there are still potential health problems in turbidity and bacterial pollution in the southeastern area and Fengjie County of Chongqing.