Spatiotemporal Variation of Coastal Water Quality in Kien Giang Province, Vietnam Using Multivariate Statistical Methods

Abstract

The study was carried out to assess coastal water quality using

multivariate statistics. The coastal water samples were collected in

the dry season (March) and wet season (September) in 2020 at eight

districts, 26 positions (KG1-KG26). The parameters of temperature

(T), pH, salinity (Sal), total suspended solids (TSS), dissolved

oxygen (DO), chemical oxygen demand (COD), ammonium

nitrogen (N-NH4

+

), phosphate (P-PO4

3-

), Coliform, iron (Fe), and

silicon dioxide (SiO2) were used for coastal water quality

assessment using national technical regulation on marine water

quality (QCVN 10-MT:2015/BTNMT), cluster analysis (CA) and

principal component analysis (PCA). The results showed that

seawater was contaminated with organic (low DO and high TSS in

some locations), microbiological, nutrient (N-NH4

+

), and metal

(Fe). The sea water environmental indicators have seasonal

fluctuations in which DO, COD, N-NH4

+

, TSS in the dry season

tended to be higher than those in the rainy season. Coliform in dry

season and rainy season were similar. The average value of iron in

the rainy season was higher than that in the dry season. COD and

SiO2 were low and not regulated in QCVN 10-MT:2015/BTNMT.

In the dry season water quality was classified into six clusters while

in the rainy season it was classified into four clusters demonstrating

spatial and temporal variation of sea water quality. Seawater in the

dry season was affected by three main sources while in the rainy

season it was only affected by two main sources. The main

indicators affecting water quality in the study area including N-

NH4

+

, Coliform, P-PO4

3-

, TSS, Fe, COD, SiO2. Further studies need

to investigate specific sources that contribute to water quality

indicators in order to have a solution to better manage sea water

quality in the study area.