Groundwater quality assessment for drinking purposes: a case study in the Mekong Delta, Vietnam.

Groundwater serves as an important resource for people in the Mekong Delta, but its quality has been continuously declined from human activities. Current status of the groundwater quality needs to be evaluated for sustainable groundwater resource management. This study aimed to evaluate the groundwater quality for drinking purposes in the Mekong Delta, Vietnam, using multivariate statistical methods and integrated-weight water quality index. Data comprised 8 water quality parameters (pH, total hardness, nitrate (NO3-), iron (Fe), lead (Pb), mercury (Hg), arsenic (As), and coliforms) obtained from 64 observation wells in An Giang province, Dong Thap province, and Can Tho city, were analyzed by cluster analysis (CA), principal component analysis (PCA), and integrated-weight water quality index (IWQI). The results indicated that most parameters were within standards while excessive hardness and Fe contamination were found in some regions. More than 80% of samples were detected with serious coliform contamination. The CA results revealed that groundwater quality heavily depend on geological locations with 4 clusters of the sampling locations. Three principal components obtained from PCA could explain 77.2% of the groundwater quality variation. The IWQI values ranging from 4 to 2761 classified groundwater quality as excellent (53.1%), good (25%), poor (9.4%), very poor (4.7%), and undrinkable (7.8%), which were associated with coliform contamination. These findings have provided insights into the groundwater quality status in the region, which can benefit in developing a water protection strategy.

Combination of water quality, pollution indices, and multivariate statistical techniques for evaluating the surface water quality variation in Can Tho City, Vietnam.

This study assessed the surface water quality in Can Tho city, Vietnam, using a combination of water quality, pollution indices, and multivariate statistical methods. Surface water samples were collected at 38 locations with a frequency of 4 times in 2020 (March, June, September, and December) and at the time of high and low tides to analyze for 18 indicators. Results showed that surface water in Can Tho city was contaminated with organic matters and microorganisms. Parameters of pH, turbidity, total suspended solids (TSS), biochemical oxygen demand (BOD), chemical oxygen demand (COD), N-NH4+, and N-NO3- are significantly increased with low tide. Comprehensive pollution index indicated mild to moderately polluted water in March, June, and September and moderately to severely polluted water in December. Organic pollution index revealed that surface water quality in all locations was polluted with organic matters during the study period especially in March and December. The water quality index also indicated that water quality in December was mostly classified as moderate and bad. The principal component analysis indicated that surface water quality could be affected by five main sources that explain 64.40% of the total variation. This significantly caused the fluctuation of pH, temperature, turbidity, TSS, DO, BOD, COD, N-NH4+, P-PO43-, Fe, and As, which should all be the focus for future monitoring. Surface water management in Can Tho city should also emphasize on the wastewater from urbanization and agriculture, which has been recognized by the analysis to have highest contribution to organic, nutrient, and microbial pollutants in the water bodies.

Classification of water quality in low-lying area in Vietnamese Mekong delta using set pair analysis method and Vietnamese water quality index.

A rational water quality assessment program directly affects a success of a national socio-economic development strategy. This study was aimed to evaluate and classify surface water quality in Dong Thap province, Vietnam, using set pair analysis (SPA) and national water quality index (WQI_VN) methods. The water quality data was collected at 58 locations in 2019 by the Department of Natural Resources and Environment of Dong Thap province. Sixteen variables including temperature (°C), pH, turbidity (NTU), dissolved oxygen (DO, mg/L), biological oxygen demand (BOD, mg/L), chemical oxygen demand (COD, mg/L), total suspended solids (TSS, mg/L), ammonia (N-NH4+, mg/L), nitrite (N-NO2-), nitrate (N-NO3-, mg/L), total nitrogen (TN, mg/L), orthophosphate (P-PO43-, mg/L), chloride (Cl-, mg/L), sulfate (SO42-, mg/L), coliform (MPN/100 mL), and Escherichia coli (MPN/100 mL) were monitored four times a year (58 water samples × 16 parameters × 4 monitoring times). The findings presented that TSS, BOD, COD, N-NH4+, N-NO2-, P-PO43-, coliform, and E. coli were the main constraints on water quality. The results of the entropy weight calculation indicated that deteriorated water quality was in the order of microbiological > nutrients > organic matters. Surface water quality was evaluated at medium (level III) and poor (level IV) by SPA and WQI_VN, respectively; however, the combination of SPA and entropy weight was considered more efficient in this classification and a positive spatial autocorrelation was also found through Moran's I. The spatial distribution of water quality based on SPA classification revealed that better water quality was found in the inner parts of the study area. Due to its ease and effectiveness, set pair analysis should be considered for inclusion in the water quality assessment program of Vietnam.

Prevalence of lower genital tract infection among women attending maternal and child health and family planning clinics in Hanoi, Vietnam.

To determine the prevalence of lower genital tract infection (LGTI) with Candida spp, Trichomonas vaginalis, Neisseria gonorrhoeae, Chlamydia trachomatis, and bacterial vaginosis among symptomatic and asymptomatic women attending maternal and child health and family planning (MCH/FP) clinics in Hanoi, Vietnam. A multi-centered, cross-sectional descriptive study stratified by reported symptoms of vaginal discharge was carried out in three MCH/FP clinics among 1,000 women aged 18-44 years in 1998. Of these, 89.1% lived in Hanoi, 97.6% were currently married, and 99.2% had only one sexual partner in the past 12 months. Regarding their contraceptive use, 28.2% did not use any contraception, 25.6% used an intrauterine device (IUD), 22.8% used condoms, and 23.4% used other methods. The overall prevalence of Candida spp was 11.1% (95% CI = 9.1-13.1%); T. vaginalis, 1.3% (95% CI = 0.6-2.0%); no gonococcal infection was found; the prevalence of C. trachomatis was 4.4% (95% CI = 3.1-5.7%); and of bacterial vaginosis, 3.5% (95% CI = 2.4-4.6%). The presence of LGTI was not associated with reported symptom of vaginal discharge. LGTI was common among married and monogamous women attending MCH/FP clinics in Hanoi, of whom many used IUDs and may have an increased risk of complications in the presence of LGTI. The lack of association between symptoms and laboratory-confirmed infection underscores the challenge of diagnosing LGTI when laboratory testing is not available.