Assessment of Coastal Surface Water Quality in Tien Giang Province, Vietnam

Abstract

The study was conducted to assess the quality of surface water

environment in the coastal area of Tien Giang province. The samples

were collected in the dry season (March-June) and in the wet season

(September-November) in 2020. The water quality variables of pH,

dissolved oxygen (DO), total suspended solid (TSS), chemical

oxygen demand (COD), ammonium (N-NH4

+

), sulfide (S2-

), chloride

(Cl-

), Coliform, zinc (Zn), arsenic (As), chromium (Cr), oil & grease

were compared with QCVN 10-MT :2015/BTNMT. CA and PCA are

used to cluster water quality and define monitoring criteria.

Research results show that pH, Zn, As, Cr, Oil and Grease, Coliform

are still within the allowable limits. COD ranges from 7 to 18 mg/L;

The sulfide concentration detected only in March was in the range

of 0.8-1.6 mg/L; The Cl-

concentration at the sampling sites ranged

from 6,447 to 12,752 mg/L. TSS at sampling locations exceeded the

allowable limit of QCVN 10-MT:2015/BTNMT from 1-1.7 times

while TSS between months exceeded the allowable limit from 1.12 to

1.9 times. N-NH4

+

concentration exceeds the allowable limit of

QCVN 10-MT:2015/BTNMT according to sampling location from 1-

1.4 times and seasonally from 1-1.6 times. Overall results show that

coastal seawater in Tien Giang province is lightly polluted with

organic matter and N-NH4

+

. Water quality has seasonal fluctuations

in which DO, TSS, S2-

, Cl-

in the dry season are higher than those in

the rainy season. In contrast, COD, N-NH4

+

in the rainy season were

higher than those in the dry season. Water quality is classified into

three clusters due to the difference of indicators COD, TSS, N-NH4

+

,

Cl-

. Cluster 1 is more polluted than the other clusters. PC1-PC4

were the main component explaining 73.4% of water quality

variation. The indicators having the main influence on water quality

in the study area include pH, COD, DO, TSS, N-NH4

+

, S2-

, Cl-

,

coliform, and Zn, which need to be continuously monitored. Further

studies should focus on investigating sources of pollution in order to

have a solution to better manage water quality in coastal areas.