Variation of Surface Water Quality in Cu Lao Dung Island, Soc Trang Province, Vietnam

Abstract

The study aims to evaluate variation of surface water quality in canals in Cu Lao Dung district, Soc Trang province, Vietnam using multivariate statistical methods. Sixteen surface water samples with the parameters of pH, total suspended solids (TSS), dissolved oxygen (DO), biological oxygen demand (BOD), chemical oxygen demand (COD), NH4+-N, NO2−-N, PO43−-P, Cl−, Fe, coliform were used for the assessment. The results showed that the surface water in the study area was contaminated with microorganisms, salinity and acidity, and nutrient. The concentrations of coliform, Cl−, Fe, TSS and NO2−-N were higher than the specified limits by 4.17, 2.04, 1.91, 1.28 and 1.10 times, respectively. The four principal components could explain up to 81.40% of the total variance of surface water quality. The main water pollution sources could be from natural (rainwater runoff, saltwater intrusion, erosion) and man-made activities from domestic and agricultural activities (livestock, aquaculture, cultivation), industry and navigation activities. Cluster analysis divided surface water quality into two groups by the difference in BOD, COD, NH4+-N, NO2−-N, Fe, coliform and pH. Pearson correlation results demonstrated that only BOD or COD should be monitored since it is mutually predictable. Specific sources and its contribution should be further studied for effective surface water quality management in the study area.