Assessment of Surface Water Quality in the Water Bodies in Aquaculture Area in Kien Giang Province, Vietnam

Abstract

The study was conducted to assess the quality of surface water in

the aquaculture area of Kien Giang province in the period of 2019-

2020. Water samples were collected twice per year (in March and

September) at seven locations designated AQ1 to AQ7. The

parameters of temperature (T), pH, salinity (S), total suspended

solids (TSS), dissolved oxygen (DO), chemical oxygen demand

(COD), ammonium (N-NH4

+

), orthophosphate (P-PO4

3-

), Coliform,

iron (Fe), and silicon dioxide (SiO2) were used to assess water

quality. The study used national regulation on marine water quality

(QCVN 10-MT:2015/BTNMT) and multivariate statistical methods

including cluster analysis (CA) and principal component analysis

(PCA) to assess water quality. The results showed that the

temperature and pH are within the allowable limits. Salinity, COD,

and SiO2 are in the ranges of 7.7-22.2‰, 18.3-22.8 mg/L, and 8-

16.3 mg/L, respectively. These criteria are not specified in QCVN

10-MT:2015/BTNMT. TSS at positions AQ5-QW7 exceeded the

allowable limit. DO at all positions in May 2019 and all sampling

periods of 2020 were below the allowable limit. N-NH4

+ appeared

at all sampling locations in March 2019 while N-NH4

+ appeared at

only a few locations in September 2019 and also in 2020. In the

locations where N-NH4

+ was found, N-NH4

+ were all over the

allowable limit. P-PO4

3- was found only at AQ1 (2019) and AQ4-

AQ6 (2020) positions. Coliform at AQ3, AQ6, AQ7 exceeded the

allowable limit of QCVN 10-MT:2015/BTNMT. Fe at all positions

has exceeded the allowable limit. The large fluctuations in time and

space of surface water quality was mainly due to COD, TSS,

salinity, N-NH4

+

, coliform, Fe, SiO2. The results of PCA analysis

showed that the parameters of pH, salinity, TSS, COD, N-NH4

+

, P-

PO4

3-

, Fe, SiO2, coliform need to be continued to be monitored

because they have the main impact on surface water quality.

Further studies need to investigate specific sources of pollution in

order to have appropriate treatment solutions