Screening environmental risk evaluation of As and trace metals in soils and sediments from a developing area (Bắc Giang Province, Northern Vietnam).

Despite the key role that areas close to the rivers Cầu and Ngũ Huyện Khê (Bắc Giang Province, Northern Vietnam) play in the socio-economic development of Vietnam, poor information is available on the level of contaminants and their natural backgrounds in local soils and sediments. To partially fill this gap and to take into account for pressures and impacts on different zones and environment types (river sediments, crop fields, family wells, industrial and urban soils), the samples were collected and analyzed for fifteen trace elements at thirty sites distributed over the province. To overcome the lack of information on natural background and to identify the extent of the deviation from natural conditions, we coupled statistical analysis to contamination indices. The multivariate analysis was used to relate sediment chemical composition with a possible alteration from secondary inputs and to highlight those samples that most deviate from the distribution by category and are potentially more problematic. Geoaccumulation indexes and enrichment factors were calculated to discriminate between natural backgrounds and anthropic sources, SQGs were used for a screening evaluation of environmental risk in the study area. Results showed relatively high concentrations, sometimes exceeding international and national guidelines, and local sources could prevail over geogenic origins. Despite its significant natural contribution all over the study area, As evidenced some cases of anthropogenic contamination, similarly to that observed for Cd, Hg, and Zn. Their high concentrations may be a problem for public health, especially when found in family wells.