The contamination characteristics of arsenic and other trace elements in groundwater and the potential risks of arsenic from the groundwater were investigated. Elevated contamination of arsenic, barium and manganese was observed in tube-well water of two villages (Chuyen Ngoai and Chau Giang) in Ha Nam province in the Northern Vietnam. Concentrations of As in the groundwater ranged from 12.8 to 884 µg/L with mean values in Chuyen Ngoai and Chau Giang were 614.7 and 160.1 µg/L, respectively. About 83 % of these samples contained As concentrations exceeding WHO drinking water guideline of 10 μg/L. The mean values of Mn and Ba in groundwater from Chuyen Ngoai and Chau Giang were 300 and 657 μg/L and 650 and 468 μg/L, respectively. The mean value of Ba concentration in groundwater in both Chuyen Ngoai and Chau Giang was about 22 % of the samples exceeded the WHO guideline (700 µg/L). Arsenic concentrations in human urine of residents from Chuyen Ngoai and Chau Giang were the range from 8.6 to 458 µg/L. The mean values of Mn and Ba in human urine of local people from Chuyen Ngoai were 46.9 and 62.8 μg/L, respectively, while those in people from Chau Giang were 25.9 and 45.9 μg/L, respectively. The average daily dose from ingesting arsenic for consuming both untreated and treated groundwater is from 0.02 to 11.5 and 0.003 to 1.6 μg/kg day, respectively. Approximately, 57 % of the families using treated groundwater and 64 % of the families using untreated groundwater could be affected by elevated arsenic exposure.

Chlorobenzenes (CBzs) are unintentionally produced organic contaminants from different thermal industrial processes, which have been scarcely surveyed in Asian developing countries including Vietnam. In this study, residue concentrations, profiles, emission factors, and annual emissions of seven chlorobenzene compounds were investigated in fly ash and bottom ash samples of some industrial facilities including brick making plant, steel and zinc production plants, and industrial and municipal waste incinerators in northern Vietnam. Total concentrations of seven CBzs in the ash samples were generally decreased in the order: industrial waste incinerator > municipal waste incinerator > steel-making plant > brick making plant. Emission pattern of CBzs varied considerably among different industrial plants, with 1,2-and 1,3-dichloro-, 1,2,3,4-tetrachloro-, and hexachlorobenzene as predominant compounds in the industrial waste incinerators and steel-making plants. Emission factors of CBzs estimated for the fly ash and bottom ash samples were in the range of 118-2020 and 5.3-22,600 μg ton −1 , respectively. Average annual emissions (AEs) of total seven CBzs estimated for fly ash and bottom ash in the investigated plants were in the range of 154-54,300 and 20,160-161,400 mg year −1 , respectively. The AEs of CBzs estimated for fly ash in the steel-making plant were higher than those in the waste incinerators. Meanwhile, CBz emissions for bottom ash were the highest in the steel-making plant, followed by the industrial and municipal waste incinerators. This is among the first studies on the emission characteristics of both low and highly chlorinated benzenes from industrial activities in Vietnam.