Assessment of Surface Water Quality Duyen Hai District, Tra Vinh Province, Vietnam

Abstract

The study was carried out to assess surface water quality in
Duyen Hai district, Tra Vinh province at 7 monitoring locations
from NM1 to NM7 with the parameters studied inclue including
pH, total suspended solids (TSS), dissolved oxygen (DO),
biological oxygen demand (BOD), chemical oxygen demand
(COD), ammonium (N-NH4
+
), nitrate (N-NO3
-
), phosphate (PPO4
3-
), iron (Fe) and coliform to assess surface water quality in
the years2020 and 2021. Surface water quality is assessed
through comparison with the national technical regulation on
surface water quality column A1 (QCVN 08-MT:2015/BTNMT).
The study has applied statistical methods including cluster
analysis and principal component analysis to group monitoring
locations with similarity in the concentrations of parameters and
determine the influencing parameters on surface water quality.
The study results showed that the water quality in the study area
appeared polluted in both years. Compared with column A1, all
water quality parameters exceeded the allowable limits of QCVN
08-MT:2015/BTNMT (except pH parameter).Cluster analysis
(CA) analysis has grouped from 7 monitoring sites into 3
monitoring groups, reducing 54% of monitoring costs for future
monitoring programs. The results of the principal component
analysis (PCA) analysis in the years 2020 and 2021 showed that
there were 81.3% and 93.3% of surface water quality changes
explained by three PCs and four PCs, respectively. All
parameters used in the study should be further monitored in the
upcoming monitoring program. Causes of pollution in the study
area could originate from natural factors, acid sulfate soil,
decomposition of plant residues in water, waste from
agricultural and livestock production, farming, aquaculture and
saltwater intrusion.