RESUMO
This first study investigated the presence of dioxins and furans in river sediments around a craft village in Vietnam, focusing on Secondary Steel Recycling. Sediment samples were collected from various locations along the riverbed near the Da Hoi Secondary Steel Recycling village in Bac Ninh province. The analysis was conducted using a HRGC/HRMS-DFS device, detecting a total of 17 dioxin/furan isomers in all samples, with an average total concentration of 288.86 ng/kg d.w. The concentrations of dioxin/furan congeners showed minimal variation among sediment samples, ranging from 253.9 to 344.2 ng/kg d.w. The predominant compounds in the dioxin group were OCDD, while in the furan group, they were 1,2,3,4,6,7,8-HpCDF and OCDF. The chlorine content in the molecule appeared to be closely related to the concentration of dioxins and their percentage distribution. However, the levels of furan isomers did not vary significantly. The distribution of these compounds was not dependent on the flow direction, as they were mainly found in solid waste and are not water-soluble. Although the hepta and octa congeners had high concentrations, when converted to TEQ values, the tetra and penta groups (for dioxins) and the penta and hexa groups (for furans) contributed more to toxicity. Furthermore, the source of dioxins in sediments at Da Hoi does not only originate from steel recycling production activities but also from other combustion sites. The average total toxicity was 10.92 ng TEQ/kg d.w, ranging from 4.99 to 17.88 ng TEQ/kg d.w, which did not exceed the threshold specified in QCVN 43:2017/BTNMT, the National Technical Regulation on Sediment Quality. Nonetheless, these levels are still concerning. The presence of these toxic substances not only impacts aquatic organisms in the sampled water environment but also poses potential health risks to residents living nearby.
Assuntos
Dioxinas , Monitoramento Ambiental , Furanos , Sedimentos Geológicos , Rios , Aço , Poluentes Químicos da Água , Rios/química , Vietnã , Sedimentos Geológicos/química , Sedimentos Geológicos/análise , Dioxinas/análise , Aço/química , Poluentes Químicos da Água/análise , Furanos/análise , Furanos/química , Monitoramento Ambiental/métodos , ReciclagemRESUMO
Phytochemical investigation of a methanolic extract of Sedum sarmentosum collected from Vietnam resulted in the isolation of a new megastigmane glucoside, named sedumoside K (1), together with 17 previously reported compounds (2-18). Structural elucidation of the new compound was achieved by HRFABMS, NMR spectroscopic analysis, acid hydrolysis and quantum ECD calculations. The absolute configuration of compounds 2-6 has been revised. The major isolates were tested for cytotoxic activity against HeLa human cervical cancer cells, and all showed moderate activities.