Analysis of Changing Trend of Fecal Coliform Levels at Lakes in Hue Citadel, Vietnam

Abstract

To determine changing trends of fecal contamination at TinhTam, CayMung, TanMieu and HoVe lakes in Hue Citadel (Vietnam), this reseach sampled and monitored the fecal coliform level every two months from March 2013 to November 2014. There were a total of 11 samples collected at each site. Samples were determined by MPN method and based on standards of APHA. Mann-Kendall non-parametric test was used to analyze and assess changing trends based on Theil-Sen slope, using ProUCL 4.1 software. The monitoring results in the 21^st month study period showed that the fecal coliform level at the lakes in Hue Citadel has large fluctuations in the rainy season (September and November). The result also indicated that TanMieu Lake has the highest level of fecal coliform. By statistical analysis and Mann-Kendall non-parametric test, the study indicated that there is an increase in the levels of fecal contamination at HoVe lake (p < 0.05), where the changing rate of the contamination at the value of 37.50 MPN/100 mL/month (450.00 MPN/100 mL/year) was also detected. The long-term solution is to prevent the discharge of the sources of fecal bacteria into the lakes in Hue Citadel.