Evaluating Groundwater Quality Using Multivariate Statistical Analysis and Groundwater Quality Index

Under pressure from surface water pollution and climate change, groundwater becomes a critical water source. Information on groundwater quality could contribute to effective groundwater management. This study was carried out to utilize multivariate statistical analysis and the groundwater quality index (GWQI) to evaluate groundwater quality in Ca Mau Province, Vietnam. Twenty-five groundwater samples from residential-urban areas, cemetery areas, landfill areas, and saline intrusion areas were collected for this study. Groundwater quality was evaluated using the National Technical Regulation on Groundwater Quality (QCVN 09-MT:2015/BTNMT) and GWQI. Principal component analysis (PCA) was used to identify potential polluting sources and key variables influencing groundwater quality. Cluster analysis (CA) was applied to cluster groundwater quality, and the sites were recommended for future monitoring. The results revealed that NH4+-N contaminated groundwater in the landfill area, while the saline intrusion area was polluted by TDS and NH4+-N. The groundwater quality classified as excellent, good, poor, and very poor accounted for 44, 40%, 12%, and 4%, respectively. Cluster analysis divided groundwater quality into four groups, mainly based on the presence of NH4+-N and TDS. Nine groundwater sampling locations could be removed from the current groundwater quality program but still ensuring representativeness as a result of CA. PCA proposed two main sources of variation in groundwater quality at each residential-urban area: the cemetery area, the landfilling area, and the saline intrusion area. The groundwater parameters (i.e., pH, TDS, permanganate index, NH4+-N, NO3--N, and Fe) should be continued to monitor. Domestic and industrial wastewater discharge, leachate from cemeteries and landfills, the nature of groundwater aquifers, and seawater intrusion could be potential sources of groundwater variation. The current findings provide scientific information for local environmental authorities to manage and monitor groundwater quality in the study area. Doi: 10.28991/CEJ-2024-010-03-03 Full Text: PD

Assessing Air Quality Using Multivariate Statistical Approaches

The purpose of the current study was to evaluate air quality in Dong Thap province, Vietnam. The air quality data was collected during 2019–2020, representing the time of pre- and mid-COVID-19. Twenty-seven air quality samples (in the areas of urban, residential-administrative, hospital-schools, and industry-craft village areas) were used for the evaluation. Air quality was evaluated using national technical regulations on air quality, including QCVN 26:2010/BTNMT and QCVN 05:2013/BTNMT. The difference of mean air quality between the areas was examined using a one-way ANOVA followed by the Duncan test at a significant level of 5%. The relationship between air quality parameters and microclimate factors was tested using Pearson correlation. Principal component analysis (PCA) was utilized to identify critical variables and potential sources of air variation. Cluster analysis (CA) was applied to group similar air quality sites, thus recommending air monitoring site selection. The results show that the air quality in the study area is not polluted. The concentrations of noise, TSP, SO2, and NO2in the mid-COVID-19 pandemic were significantly lower than those in the pre-COVID-19 pandemic due to the social distancing policy. There was a close correlation among air quality parameters, except for air humidity. PCA identified two to four potential sources of air variation, explaining 84.3%, 100%, 100% and 89.7% of the total air quality variance at urban, residential–administrative, hospital-schools, and industry-craft villages, respectively. CA divided the 27 sampling sites into eight groups by the differences, mainly in humidity, wind speed noise, TSP, and CO. Eight sampling sites could be potentially reduced from the current monitoring program for representativeness and cost-effectiveness purposes. All air parameters in the current study are significant for monitoring, and the potential sources of air quality variation are traffic activities, industrial production, craft village activities, and daily life using fuels in residential areas. The results of the current study provide useful information for air quality monitoring and management. Future monitoring programs should include toxic air pollutants in air quality monitoring programs. Doi: 10.28991/CEJ-2024-010-02-012 Full Text: PD

Evaluating Surface Water Quality in Ninh Kieu District, Can Tho City, Vietnam

This study aimed to evaluate water quality in the canals in Ninh Kieu district, Can Tho city in the period of 2018-2019. Monitoring data were collected at 10 locations distributed on Tham Tuong canal (TT1, TT2), Cai Khe canal (CK1-CK4), Bun Xang lake (BX1-BX2), Cai Son - Hang Bang canal (HB1, HB2). Water quality parameters assessed include temperature, pH, turbidity, total suspended solids (TSS), biological oxygen demand (BOD), chemical oxygen demand (COD), orthophosphate (PO43--P), nitrate (NO3-- N), ammonia (NH4+-N), nitrite (NO2-- N) and coliforms. The results showed that water quality in the canals in Ninh Kieu district, Can Tho city were contaminated with coliforms, TSS, BOD, and COD. The temperature and pH parameters were very little fluctuated, while BOD, coliforms, and DO tended to decrease in the period from 2018-2019. Particularly, the mean P-PO43- in 2019 was higher than that in 2018. BOD, COD, TSS, P-PO43-, and coliforms in Tham Tuong canal were higher than those in other water bodies because several production and business activities are taking place. Water pollution problem in Ninh Kieu district, Can Tho city needs to be solved as soon as possible to ensure healthy environment, attracting tourists to visit in Can Tho city

Evaluating Current Water Quality Monitoring System on Hau River, Mekong Delta, Vietnam Using Multivariate Statistical Techniques

This study aims to assess the sampling sites and frequencies of sampling of the existing surface water quality monitoring on Hau River using multivariate analysis techniques. Principal Component Analysis (PCA) and Cluster Analysis (CA) were used to analyze the water quality monitoring data collected every month in 2018 from 8 sampling stations. Surface water quality parameters including pH, temperature, dissolved oxygen (DO), total suspended solids (TSS), nitrate (N-NO3-), phosphate (P-PO43-), chemical oxygen demand (COD) and coliforms were used in the PCA and CA analyses. The findings indicated that the Hau River water quality was polluted by TSS, COD and coliforms in which COD was high in dry season, TSS was high in wet season and coliforms were high all year round. The PCA revealed that pH, temperature, DO, TSS, N-NO3-, P-PO43-, COD and coliforms influenced on the water quality, therefore, relevant for examination in the water samples. These water quality variables were affected by various polluting sources, for examples, runoff, human activities, and hydrological influence. Cluster analysis suggested that the current monitoring program could be reduced from 8 to 3-4 points and 12 to 3-4 times per year. This monitoring program could save the total budget for up to 42%. The findings of the present study could be useful to the policy maker especially to those who are dealing with surface water monitoring systems. The multivariate statistical techniques could be used to assess the surface water quality monitoring network

Risks of Surface Water Pollution in Southern Vietnam

The study was carried out to assess surface water quality and ecological risks in water bodies in the southern region of Vietnam. The study used monitoring data at 58 locations, which were collected in March, May, June, July, August, October, November, and December of 2022, with 11 water quality parameters (temperature, pH, DO, TSS, BOD, COD, NH4+-N, NO3--N, Fe, Pb, and Cd). Comprehensive pollution index (CPI), ecological risk level, and multivariate statistical analysis methods were utilized. The values of CPI showed that the surface water quality was mildly polluted, moderately polluted, and severely polluted, accounting for 37.93, 46.93, and 15.52%, respectively. In particular, heavy pollution was concentrated in the water bodies of the Sai Gon and Vam Co Rivers. TSS, BOD, COD, NH4+-N, and Fe had a moderate to high level of risk, while water samples contaminated with NO3--N, Pb, and Cd had a level of risk from low to safe. High levels of risk were concentrated in the water bodies of the Sai Gon River and Vam Co River, typically BOD and COD. Based on the impact level, the positions were classified into five groups, with the locations on the Sai Gon River and Vam Co River (Groups 4 and 5) being affected by various waste sources in the inner city of Ho Chi Minh City. The PCA results presented three sources, such as discharge from residential areas, soil erosion, and agriculture, that have caused water quality fluctuations and increased the impact on the water quality of water bodies. Measures to protect water resources according to environmental protection laws must be implemented soon to minimize ecological risks from water-polluting sources. Doi: 10.28991/CEJ-2023-09-11-06 Full Text: PD

Evaluating the Importance of Ecosystem Services in University Campus

University campuses provide a variety of ecosystem services (ES) that play an important role in both physical and mental benefits for students. However, the importance and actual service performance of ES in universities were not clearly perceived in Vietnam. This study was conducted to fill these gaps with the objectives of (1) assessing students' perceptions of the importance of ecosystem services on their university campus and (2) assessing students' satisfaction with these ecosystem services. Using the interview method, the study collected research data from 210 students at Can Tho University (CTU), a large university in Vietnam. The results of the study have confirmed the importance of ecosystem services such as trees, lawns, water bodies, and buildings on CTU's campus. With modern design, buildings play an important role in creating space to organize formal classes, self-study, and group work for students. Green spaces not only improve air temperature and bring high aesthetic value, but they are also habitats for many species of animals and plants. Most students were very satisfied with the ES provided by the CTU's campus. However, the functions of the grass and water bodies ecosystem need to be improved, as the student satisfaction with these ES was significantly lower than the value they expected. The results of analyzing the importance and satisfaction of ES will be a useful basis for making decisions on planning and developing ecosystems. This is a new research direction in Vietnam that needs continued research and application. Doi: 10.28991/CEJ-2024-010-01-015 Full Text: PD

Characterization of Groundwater Quality and Human Health Risk Assessment

The study aimed to appraise groundwater quality in the Mekong Delta using a groundwater quality index (GWQI) and estimate human health risks associated with groundwater consumption. Groundwater samples were collected at sixty wells distributed in An Giang, Kien Giang, Hau Giang and Dong Thap provinces. Twelve water quality parameters were measured, including pH, total dissolved solids (TDS), hardness, coliform, nitrate (NO3ˉ), nitrite (NO2ˉ), ammonium (NH4+), sulfate (SO42-), iron (Fe), manganese (Mn), arsenic (As) and cadmium (Cd). The results were compared with the national regulation on groundwater quality. The findings of this study indicated that groundwater in the Mekong Delta was contaminated with microorganisms and some heavy metals (Fe, Mn, and As). This was related to anthropogenic activities, such as improperly treated domestic wastewater and agricultural and industrial wastes. Based on the results of GWQI, 30% of the total groundwater samples in the Mekong Delta were classified as very good for drinking purposes. However, over 26% of all samples were unsuitable for drinking. In terms of risk assessment, children were rather susceptible to cancer risks and adverse health effects through drinking As-contaminated groundwater than adults. The cancer risks of consuming As-contaminated groundwater for children and adults were up to 4.28×10-3that is higher than the acceptable risk. The highest aggregate hazard quotient of heavy metal-contaminated groundwater for children and adults was 9.54, which means that they could suffer adverse health effects. Groundwater is an indispensable source of freshwater in the Mekong Delta; thus, home water treatments are recommended to protect public health, and an in-depth groundwater quality and health risk assessment should be conducted. Doi: 10.28991/CEJ-2023-09-03-09 Full Text: PD

Ecological Risk Associated with the Occurrence of Heavy Metals in Agricultural Soil in Soc Trang Province, Vietnam

The study aimed to evaluate the content and potential ecological risks due to the presence of toxic elements (Pb, Cu, Cr, Zn, As) in agricultural soil in Soc Trang province. Data of five heavy metals and physical factors at eight sites (from D1 to D8) in three ecological zones (fresh, brackish and saline agricultural activities) in the study were collected from the Department of Natural Resources and Environment of Soc Trang province. Multivariate statistical analyzes, including principal component analysis (PCA), correlation analysis (Pearson), cluster analysis (CA) and potential ecological risk index (RI), were used in the study. The results showed that the content of Pb, Cu, Cr, Zn and As fluctuated in the range of 8.54–30, 21.90–28.10, 20.60–38.70, 46.80–86, 1.35–11.30 mg/kg, respectively, within the allowable limits of QCVN 03-MT:2015/BTNMT. The soil in the study area has moderate to neutral acidity, suitable for growing crops. The Pearson and PCA results showed that the inputs in local agricultural development (fertilizers, pesticides, fungicides, and herbicides) have contributed to the increase of heavy metal content in the soil. The results of the CA grouped eight soil samples into two large groups belonging to the ecological areas (brackish, saline) and freshwater. The mean RI value of 68.84 indicated low potential ecological risks in agricultural land in Soc Trang province. However, As and Cr are heavy metals that would pose significant potential risks to the environment and humans. Thus, measures are needed to strictly control the sources of these metals

Recommending Surface Water Quality Monitoring for the Nature Reserve Using Multivariate Statistical Methods

Lung Ngoc Hoang Nature Reserve has a crucial role in conserving and protecting the natural ecosystem and biodiversity in the Mekong Delta, Vietnam, and the local communities also receive great benefits from aquatic resources in this nature reserve. This study was conducted to assess water quality in the Lung Ngoc Hoang Nature Reserve and to provide important information for the monitoring program using multivariate statistical methods. Water samples were collected bimonthly from fifteen locations belonging to five functional zones of the nature reserve (i.e., buffer zone, main canal, administrative and service zone, ecological restoration zone, and strictly protected zone). The physiochemical properties of water samples were measured, including temperature, pH, electrical conductivity (EC), total suspended solids (TSS), dissolved oxygen (DO), biochemical oxygen demand (BOD), chemical oxygen demand (COD), total nitrogen (TN), total phosphorus (TP), sulfate (SO42-), iron (Fe2+), and aluminum (Al3+). The results showed that the levels of TSS, COD, and Fe2+ exceeded the Vietnamese standard on surface water quality, and the DO level was also far below the standard. Besides, the concentrations of TN, TP, and Al3+ in the nature reserve area showed the risk of eutrophication and negative effects on aquatic organisms. Problems of water quality were observed in the main canal and the administrative and service zones more than in the other zones. Cluster analysis (CA) suggested a reduction in the number of monitoring frequencies and locations to four months (i.e., January, April, July, and September) and twelve locations, respectively. This reduction allows for a decrease in the effort and cost of the monitoring program with adequate information to evaluate water quality. Moreover, principal component analysis (PCA) identified five principal components, which could explain 80.98% of the total variance of the initial dataset. Potential pollution sources were also recognized based on PCA, including the nature properties of sulfate-acid soils, livestock, fertilizer, and domestic activities. The findings of this study can enhance our understanding of water quality in the nature reserve area and the effectiveness of future monitoring programs. Doi: 10.28991/CEJ-SP2023-09-015 Full Text: PD