Evaluating Surface Water Quality in Cai Nuoc River, Ca Mau Province, Vietnam

This study aims to evaluate surface water quality in Cai Nuoc River, Ca Mau province using a water quality index and principal component analysis. Surface water quality is assessed using National Technical Regulation on surface water quality (QCVN 08-MT:2015/BTNMT, Column B1), water quality index (WQI), eutrophication index (EI) with the support of principal component analysis (PCA). Nine water quality parameters of pH, DO, TSS, COD, BOD, N–NH4+, P–PO43-, N–NO3- and coliform were used for the evaluation and index calculations. The results presented that surface water quality in Cai Nuoc River was polluted by low DO and high N–NH4+ and P–PO43-. The WQI index classified water quality from average to very good (WQI= 73-94), relatively suitable for the survival and development of aquatic organisms. Meanwhile, the EI index showed the water bodies was in the stages of the poor to super eutrophication, mainly due to aquaculture and seafood processing activities. PCA determined three potential sources responsible for 100% of water quality fluctuations. The problems of organic and nutrients pollution in the study areas should be urgently solved to preserve diversity of aquatic organisms.