Assessing surface water quality in Cai Rang district, Can Tho city

Abstract

This study aims to assess surface water quality in rivers and canals in Cai Rang district, Can Tho city. Water quality data for the period 2013 - 2019 was collected at five locations (Cai Rang market - CR1, Cai Cui site - CR2, Cai Dep site - CR3, and canal of Ben Ba - CR4, Cai Rang Be - CR5) with 17 water quality parameters including pH, temperature, total suspended solids (TSS), turbidity, dissolved oxygen (DO), biochemical oxygen demand (BOD), chemical oxygen demand (COD), ammonia (NH₄⁺-N), nitrite (NO₂^--N), nitrate (NO₃^-- N), orthophosphate (PO₄^3--P), coliforms, iron (Fe), chromium (Cr⁶⁺), fluorine (F^-), lead (Pb) and arsenic (As). Water quality was compared with national technical regulations on surface water quality (QCVN 08-MT: 2015/BTNMT). The results showed that the study area was organic pollution (low DO, high BOD and COD). Correlation analysis showed that TSS, turbidity, organic compounds, nitrogenous and phosphorus compounds, heavy metals (Fe, As, Cr⁶⁺) were positive correlation. Principal component analysis (PCA) showed that there were 13 indicators (pH, temperature, TSS, turbidity, DO, NO₂^--N, NO₃^-- N, PO₄^3--P, coliforms, Fe, Cr⁶⁺, F^-, and As) affecting surface water quality and such parameters should be included in the monitoring program. PCA also presented four main factors that explained 91.5% of the variation in water quality in the study area. The sources of pollutants were mainly from domestic, agricultural, industrial wastewater, water traffic and storm water runoff. The study provides important information on surface water quality in Cai Rang district, Can Tho city, contributing for the management of surface water environment there.