Antibiotic residues and antimicrobial resistance in surface water are issues of global concern, especially in developing countries. In this study, the occurrence of seven antibiotics and one ...antiparasitic agent was determined in surface water samples collected from four rivers running through Hanoi urban area in the Red River Delta, northern Vietnam. The pharmaceuticals in water samples were analyzed by solid-phase extraction combined with liquid chromatography–tandem mass spectrometry method. The concentrations of pharmaceuticals in our samples ranged from 3050 to 16,700 (median 7800) ng/L, which were generally higher than levels found in river water from many other locations in the world. Amoxicillin, oxfendazole, and lincomycin were the most dominant and frequently detected compounds (detection rate 100%), which together accounted for 76 ± 14% of total concentrations. Sulfacetamide and sulfamethoxazole were detected at moderate concentrations in more than two-thirds of the analyzed samples. The remaining antibiotics (i.e., azithromycin, ciprofloxacin, and ofloxacin) were found at lower detection frequency and concentrations. Antibiotic concentrations in the water samples were not significantly different between the investigated rivers. Meanwhile, levels of pharmaceuticals in the samples collected in February 2020 were higher than those found in the remaining samples, largely due to the sharp decrease in sulfamethoxazole and azithromycin concentrations of the samples collected in March and April. Considerable ecological risks of antibiotics in surface water were estimated for some compounds such as amoxicillin, ciprofloxacin, and ofloxacin.
Microplastics (MPs) are small (< 5 mm) plastic particles that are widely found in marine, freshwater, terrestrial and atmospheric environments. Due to their prevalence and persistence, MPs are ...considered an emerging contaminant of environmental concern. The separation and quantitation of MPs from freshwater sediments is a challenging and critical issue. It is necessary to identify the fate and sources of MPs in the environment, minimise their release and adverse effects. Compared to marine sediments, standardised methods for extracting and estimating the amount of MPs in freshwater sediments are relatively limited. The present study focuses on MP recovery efficiency of four commonly used salt solutions (NaCl, NaI, CaCl
2
and ZnCl
2
) for isolating MPs during the density separation step from freshwater sediment. Known combinations of artificial MP particles (PS, PE, PVC, PET, PP and HDPE) were spiked into standard river sediment. Extraction using NaI, ZnCl
2
and NaCl solutions resulted in higher recovery rates from 37 to 97% compared to the CaCl
2
solution (28–83%) and varied between polymer types. Low-density MPs (PE, HDPE, PP and PS) were more effectively recovered (> 87%) than the denser polymers (PET and PVC: 37 to 88.8%) using NaCl, NaI and ZnCl
2
solutions. However, the effective flotation of ZnCl
2
and NaI solutions is relatively expensive and unsafe to the environment, especially in the context of developing countries. Therefore, considering the efficiency, cost and environmental criteria, NaCl solution was selected. The protocol was then tested by extracting MPs from nine riverine sediment samples from the Red River Delta. Sediments collected from urban rivers were highly polluted by MPs (26,000 MPs items·kg
−1
DW) compared to sediments located downstream. Using a NaCl solution was found to be effective in this case study and might also be used in long-term and large-scale MP monitoring programmes in Vietnam.
This review provides focused insights into the contamination status, sources, and ecological risks associated with multiple classes of antibiotics in surface water from the East and Southeast Asia ...based on publications over the period 2007 to 2020. Antibiotics are ubiquitous in surface water of these countries with concentrations ranging from <1 ng/L to hundreds μg/L and median values from 10 to 100 ng/L. Wider ranges and higher maximum concentrations of certain antibiotics were found in surface water of the East Asian countries like China and South Korea than in the Southeast Asian nations. Environmental behavior and fate of antibiotics in surface water is discussed. The reviewed occurrence of antibiotics in their sources suggests that effluent from wastewater treatment plants, wastewater from aquaculture and livestock production activities, and untreated urban sewage are principal sources of antibiotics in surface water. Ecological risks associated with antibiotic residues were estimated for aquatic organisms and the prevalence of antibiotic resistance genes and antibiotic-resistant bacteria were reviewed. Such findings underline the need for synergistic efforts from scientists, engineers, policy makers, government managers, entrepreneurs, and communities to manage and reduce the burden of antibiotics and antibiotic resistance in water bodies of East and Southeast Asian countries.
Display omitted
•Antibiotic contamination status in East/Southeast Asia's surface water is reviewed.•Antibiotics are ubiquitous in surface water, especially in aquaculture and urban areas.•Antibiotic levels varied greatly from few ng/L to hundreds μg/L in surface water.•Ecological risks and prevalence of antibiotic resistance were widely observed.•Regional monitoring studies and environmental guidelines for antibiotics are needed.
Coastal aquaculture contributes significantly to the local economy of many countries however water quality issues in the coastal regions are threatening the sustainability of this economic activity. ...This paper presents the analysis of seven heavy metals (HM) in surface seawater and wastewater from the Red River coastal aquaculture zone during 2019–2020. HM concentrations (μg.L−1) from 72 seawater samples were: Zn: 60.76 (0.5–188.0); Cu: 26.91 (0.10–96.0); Pb: 7.27 (0.8–31.2); Cr: 6.71 (0.6–28.4); As: 1.38 (0.15–5.78); Cd: 0.44 (0.04–2.41); and Hg: 0.34 (0.02–1.39). All mean values of HM in seawater were lower than the Vietnam regulatory limits for aquaculture seawater although high individual HM concentrations were found in some isolated seawater samples. Concerning wastewater quality, only mean As concentration was higher than the Vietnam regulatory limit for surface water quality, despite the fact that high concentrations of other individual HM were observed. The PCA analysis on the entire dataset of seawater and wastewater samples revealed that HM concentrations in seawater originate from various sources including human activities and natural conditions. The total potential ecological risk index (averaging 18.6; from 7.48 to 39.05) for the Red River coastal zone is in the low range. These results provide a scientific basis for better management of the coastal environment which is important for the sustainable development of the aquaculture industry in this area.
Display omitted
•Observation of heavy metal concentrations in aquaculture seawater and wastewater in the Red River coastal zone.•As concentrations were sporadically higher than the Vietnam norms, although mean concentrations were always lower.•Need for better wastewater management in the coastal aquaculture zone.
Improper processing activities of e-waste are potential sources of polycylic aromatic hydrocarbons (PAHs) and their derivatives, however, information about the environmental occurrence and adverse ...impacts of these toxic substances is still limited for informal e-waste recycling areas in Vietnam and Southeast Asia. In this study, unsubstituted and methylated PAHs were determined in surface soil and river sediment samples collected from a rural village with informal e-waste recycling activities in northern Vietnam. Total levels of PAHs and MePAHs decreased in the order: workshop soil (median 2900; range 870–42,000 ng g−1) > open burning soil (2400; 840–4200 ng g−1) > paddy field soil (1200; range 530–6700 ng g−1) > river sediment samples (750; 370–2500 ng g−1). About 60% of the soil samples examined in this study were heavily contaminated with PAHs. Fingerprint profiles of PAHs and MePAHs in the soil and sediment samples indicated that these pollutants were mainly released from pyrogenic sources rather than petrogenic sources. The emissions of PAHs and MePAHs in this area were probably attributed to uncontrolled burning of e-waste and agricultural by-products, domestic coal and biomass combustion, and traffic activities. Carcinogenicity and mutagenicity of PAHs in the e-waste workshop soils were significantly higher than those of the field soils; however, the incremental lifetime cancer risk of PAH-contaminated soils in this study ranged from 5.5 × 10−9 to 4.6 × 10−6, implying acceptable levels of human health risk. Meanwhile, concentrations of some compounds such as phenanthrene, anthracene, fluoranthene, benzaanthracene, and benzoapyrene in several soil samples exceeded the maximum permissible concentrations, indicating the risk of ecotoxicological effects.
Display omitted
•PAHs and MePAHs were found in e-waste soil and sediment at elevated concentrations.•PAH/MePAH levels decreased: workshop ≈ open burning > field soil > sediment.•Mixed pyrogenic sources were revealed, e.g., e-waste, biomass, and coal combustion.•Cancer risk of PAH-contaminated soil was generally acceptable.•Some PAHs may exhibit ecotoxicological risk for soil and freshwater life.
Urban rivers are significantly impacted by anthropogenic pressure. This study presents the updated assessment of the concentrations of 11 metals and other variables (pH, total organic carbon (TOC) ...and nutrients (total nitrogen, total phosphorus, and total silica)) in the sediments of four urban rivers in inner Hanoi city, Vietnam, during the period 2020–2022. The mean concentrations of Fe, Zn, As, and Cr were higher than the permissible values of the Vietnam National technical regulation on the surface sediment quality. Moreover, Zn and Cr were at the severe effect level of the US EPA guidelines for sediment quality. The calculation of pollution indices (
I
geo
and EF) demonstrated that Mn, Ni, and Fe were from natural sources whereas other metals were from both anthropogenic and natural sources. The ecological risk index revealed that metals in Hanoi riverine sediments were classified at considerable ecological risk. High values of metals, TOC, and nutrients in the sediments of these urban rivers mostly originate from the accumulation of untreated urban wastewater that is enhanced by low river discharge. Our results may provide scientific base for better management decisions to ensure environmental protection and sustainable development of Hanoi city.
Contamination of aquaculture products by pathogenic organisms is a major concern in areas where this activity is of high economic importance. The abundances of total coliforms (TC), Escherichia coli ...(EC) and faecal streptococci (FS) (in CFU.100 mL−1) in seawater in the Red River coastal aquaculture zone were determined. The results showed TC numbers (200 to 9100; average 1822), EC (<100 to 3400; average 469) and FS (<100 to 2100; average 384), of which TC exceeded the allowable threshold of the Vietnam regulation for coastal aquaculture water. TC and EC numbers in 4 wastewater types (domestic, livestock farming sewage, agricultural runoff, and mixed sewage canals) were investigated and revealed the importance of point sources of faecal contamination in seawater. These results underline the need to reduce the release of untreated wastewater and to put into place seawater microbial quality monitoring in areas where the development of sustainable aquaculture is an objective.
Display omitted
•FIB contamination was observed in aquaculture area of Red River delta, Vietnam.•Point source and environmental factors affect FIB concentration seawater.•Need to reduce untreated wastewater release for sustainable aquaculture development.
Surface water is used by 50% of the global population as a source of drinking water. It is therefore important to have an understanding of the quality of surface water used for this purpose, given ...its potential risk to human health. We studied fecal indicator bacteria FIB; comprising total coliforms (TC),
Escherichia coli
(EC) and fecal streptococci numbers along with 28 other water quality variables in Hoa Binh reservoir, Vietnam during six sampling campaigns undertaken from July 2023 to January 2024. Hoa Binh is a multi-purpose reservoir used for aquaculture, drinking water for local cities and Hanoi, the capital, which is downstream of the reservoir, and irrigation. Of the measured FIB, the mean value of TC exceeded that permitted by the Vietnam technical regulation for surface freshwater, QCVN 08-MT:2023/BTNMT. The mean values of the other variables, except for total nitrogen, were within the limits, although the maximal values of total organic carbon and total phosphorus exceeded them. Different point sources, including those originating from the local human population, tourists, livestock farming and fish cage farming, and diffuse sources from agriculture, comprise the major sources of contamination of the reservoir. Due to the importance of Hoa Binh reservoir for the provision of drinking water for Hanoi, the largest city of Vietnam, our results indicate the need to regularly monitor the quality of the water in the reservoir to provide a scientific basis for the implementation of timely measures to protect it. Our results also contribute to filling the knowledge gap on the microbial quality of water in developing countries.
Unsubstituted and methylated polycyclic aromatic hydrocarbons (22 PAHs and 17 Me-PAHs) were examined in surface sediments collected from the Red River and four inner-city rivers of Hanoi City, ...Vietnam. Concentrations of total PAHs and Me-PAHs ranged from 52 to 920 (median 710) and from 70 to 2600 (median 1000) ng/g dry weight in samples of dry and wet seasons, respectively. Significant correlation was observed between total PAHs and organic carbon contents (Spearman's
ρ
= 0.782;
p
< 0.05). PAHs were more abundant than Me-PAHs in all samples and dominated by 4–6 ring compounds. The most predominant PAHs were benzo
ghi
perylene, benzo
b/j
fluoranthene, chrysene, pyrene, fluoranthene, and phenanthrene. Methylated derivatives of naphthalene, phenanthrene, anthracene, and benz
a
anthracene were frequently detected. The patterns of PAHs indicated principal pyrogenic sources (notably gasoline exhaust) in this highly urbanized area. The occurrence of several PAHs were occasionally associated with adverse effects on benthic organisms of the inner-city rivers.
Urbanisation and demographic growth are putting pressure on surface water quality in many large cities. Microbial water quality, as determined by the presence of fecal indicator bacteria (FIB) was ...investigated in 15 urban lakes in the inner city of Hanoi, Vietnam from 2021 to 2023. FIB (total coliforms, TC and Escherichia coli, EC) numbers exceeded the allowed values of the Vietnam technical regulation for surface freshwater QCVN 08-MT:2015/BTNMT in most studied lakes. High domestic sewage discharge from residential areas and surface runoff from surrounding areas were the major sources of lake water pollution. High FIB numbers in these lakes mean that the use of water for market gardening or leisure activities or the consummation of fish and other aquatic products from these lakes may pose a risk to the population. These results provide the base of a dataset on water quality, which is a necessary precursor for any scientifically based management plan.
