Residue and ecological risk assessment of Polybromine diphenyl ethers (PBDEs) in the surface water of West Lake, Hanoi
| Meeting | VIWC2026 |
| Topic | OS4: Water quality and Aquaculture |
| Author | Huyen Vu Thu | Toan Vu Duc |
| Organization | Hanoi University of Natural Resources and Environment. | Research of Organic Matter (ROOM), Environmental and Life Science Research Laboratory, Thuyloi University, Vietnam |
| ID | 2023.1676260484 |
Content
1. Introduction
For the purpose of flame retardants in products, people have synthesized and produced PBDEs since the first decades of the 20th century. PBDEs are a family of 209 isomers and congener (divided into 10 groups according to the number of Br in the product). Substances in the PBDEs family have high boiling points (in the range of 310oC - 425oC), low cost production and are used as additives in many polymers (poly vinylchloride, polypropylene, poly ester, poly ethylene terphthalate, poly acrylnitrite, etc.) poly amide, poly butylene terphthalate, poly urethane, epoxy resin, phenol resin...), greatly increase the fire resistance of plastic products. Bromine flame retardant is widely used in explosion-proof materials such as furniture, textiles, plastics, building materials, electrical appliances and electronic equipment to prevent fire. The global production of these techniques was 67,440 tons in 2001 (Olisah et al., 2020)
Since 1990, when strange effects on humans and domestic animals were discovered, many studies began to focus on PBDEs. The results obtained are worrisome as this family of substances has the potential to be toxic to humans and animals. The main effects include endocrine disorders, affecting the human brain, liver, and kidneys. PBDEs can enter the environment by evaporation from plastic products, dust from electronic waste, exhaust fumes from municipal solid waste incinerators, and then entering the food chain (accumulation). in food such as fish, beef...) and then into the human body (eating, breathing, skin contact). They persist in the environment for a long time, are hydrophobic, bioaccumulative and highly contagious. Many studies show that PBDEs has accumulated in blood, human milk and environmental components such as air, soil, and sediment in many countries around the world.
West Lake, in addition to its extremely important ecological significance, the lung of Hanoi, is also a symbol of the thousand-year-old capital with the surrounding environment and landscape creating a harmonious natural picture. However, West Lake is facing pollution without many really effective treatment solutions. Pollution appears on the lake more and more affecting the landscape, lake water quality as well as the daily life of people living along the lake. Based on the current status of the West Lake area, the study mainly clarified the residual problems and risks in lakes and lakes of some typical PBDEs substances in the aquatic environment.
2. Materials and methods
2.1 Methods of investigation, data collection
Using the method to investigate information on the main waste sources of West Lake. At the same time, collect information of existing researches in the country and in the world on research subjects
Sampling locations were selected to represent the space and waste sources of the study area. Based on the field survey, ten sampling locations were selected (symbols from M1 to M10), from locations near the beginning of To Ngoc Van street to the end of Lac Long Quan street. At each location, take a surface water sample in December 2021 (sample symbols from NM1 to NM10). The distance between sampling locations ranges from 800 m to 900 m. The steps are followed: TCVN 6663-1:2011 (ISO 5667-2:2006), Water quality – Sampling – Part 1: Technical guidance for taking QCVN 08-MT:2015/BTNMT 6 samples; TCVN 6663-3:2003 (ISO 5667-3:1985) Water quality – Sampling – Part 3: Guidelines for storage and handling of samples; TCVN 5994:1995 (ISO 5667-4:1987) - Water quality - Sampling. Guide to sampling in natural and artificial ponds.
2.2 Sample analysis method
Treat the sample with liquid extraction according to EPA method 3510C and clean the sample according to EPA Method 3630C. Samples after extraction and cleaning were injected into a gas chromatograph mass spectrometer (GC-MS).
2.3 Methods of risk assessment
The environmental risk posed by PBDEs in West Lake surface water was assessed using the risk quotient (Risk quotient, RQ). RQ is calculated according to the formula:
RQ = C / MAC (formula 1)
Where: C: concentration of research substance
MAC (Maximum allowable concentration): the maximum allowable concentration for the research substance in the medium. The levels of risk are classified as: very low risk (RQ ≤ 0.01), low risk (0.01 < RQ ≤ 0.1), medium risk (0.1 < RQ < 1) , high risk (RQ > 1) (Trân L.T.H, n.d.)
3. Results and discussion
3.1 Assessment of PBDE pollution in West Lake
The analysis results showed that all 7 selected PBDEs were detected in the lake water samples and are shown in Figure 1.
Image 1. PBDE concentration (µg/l) in West Lake water in December 2021
Analytical results in December 2021 obtained the concentration of Σ7PBDEs in West Lake surface water ranging from 26.78 to 77.36 µg/l. The general assessment from Table 1 shows that the concentration of Σ7PBDEs and its components tended to decrease gradually according to the positions from NM5 > NM10 > NM1 > NM6 > NM7 > NM9 > NM3 > NM2 > NM4 > NM8. According to the results in Figure 1, it is easy to see that the total PBDEs concentration at NM5 has the highest value of 77.36 µg/l and the lowest concentration at NM8 is 26.78 µg/l. The concentration of Σ7PBDEs did not decrease gradually along the length of the studied lake, but reached the highest value at NM5, which is near Trich Sai road. This may be because in this location PBDEs emissions from activities in apartment buildings, and restaurants and hotels nearby, are the most significant. From those sources, PBDEs enters the wastewater, affecting the lake water quality at point NM9. At the same time, the above study has clarified that PBDEs can not only spread by air, but also can be spread on the surface, entering the surface water on West Lake.3.2 Evaluation of PBDEs composition in West Lake water
The composition of PBDEs in lake water is related to the change and physicochemical properties of each PBDEs. The average percentage of PBDEs in the lake water samples is presented in Figure 2.
Image 2. Average percent of 7 PBDEs in water samples December 2021
The results showed that the average percentage of 7 PBDEs (Figure 2) did not change much over the sampling time. At positions NM3 and NM8, Tribromodiphenyl ether and Heptabromodiphenyl ether have the largest average percentage compared to the remaining positions. In 7 PBDEs, PBDEs is produced in larger volume and more application than other PBDEs. The results of analyzing the percentage of PBDEs in the lake water sample showed that there was a match for the physicochemical properties of PBDEs and the ability of PBDEs to change in the environment.PBDEs has penetrated into the water surface of West Lake and from there has the ability to spread in a wide range. Risk assessment due to PBDEs in water is necessary to consider the potential impact on water quality of West Lake water environment. From there, the RQ values at the sampling points are calculated and presented in Table 1.
| PBDE | MPC (mg/l) | RQ December 2021 | |
| Min | Max | ||
| PentaBDE | 53 | 0.030 | 0.269 |
| OctaBDE | 17 | 0.113 | 0.552 |
4. Conclusion
PBDEs pollution in surface water at West Lake, Hanoi has occurred on a large scale. The concentration of Σ7PBDEs ranged from 26.78 µg/l to 77.36 µg/l. Heptabromodiphenyl ether was the predominant percentage in water samples (average 60%). The level of environmental risk posed by PBDEs ranges from low to moderate. Because PBDEs has the potential to cause endocrine disorders to humans, it is very important to continue to monitor in the next time.
Acknowledgement
The authors would like to thank the strong research group (Research of Organic Matter, ROOM), Environmental and Life Science Research Laboratory, Thuyloi University for their support during the research.
5. Reference
Olisah, C., Okoh, O. O., & Okoh, A. I. (2020). Polybrominated diphenyl ethers (PBDEs) in surface water and fish tissues from Sundays and Swartkops Estuaries, Eastern Cape Province, South Africa: Levels, spatial distribution, seasonal variation and health implications. Regional Studies in Marine Science, 36, 101319. https://doi.org/10.1016/j.rsma.2020.101319
Trân L.T.H. (n.d.). Đánh giá rủi ro môi trường. Nhà xuất bản Khoa học và Kỹ thuật, 2018. Keywords: PBDEs, benthich animals
