Risk Assessment of Heavy Metals in Sediment Samples from the Mae Chaem River, Chiang Mai, Thailand

Abstract

Heavy metals are significant environmental pollutants that are recognized as posing a potential health hazard to human beings. We investigated the concentrations of the heavy metals As, Cd, Cr, Cu, Ni, Pb, and Zn in surface sediments collected from the Mae Chaem River in Chiang Mai, Thailand, during the dry season in 2021. The mean concentrations of heavy metals in sediments were, in decreasing order, Zn > Cr > As > Pb > Ni > Cu > Cd. The mean values of As, Cd, Cr, and Cu were determined to be 32.5 ± 18.3, 0.33 ± 0.07, 45.8 ± 11.9, and 21.9 ± 7.42 mg Kg−1, respectively. These levels are higher than their standard levels in Thailand, namely 10.0, 0.16, 45.5, and 21.5 mg Kg−1, respectively. Principal component analysis (PCA) revealed that the primary origins of heavy metal contamination are predominantly attributed to residential settlements and agricultural areas. The hazard quotient (HQ) was used to estimate the non-carcinogenic risk of exposure to heavy-metal-bound surface sediments for both children and adults. The results showed that the HQ values for both groups were less than 1.0 (HQ < 1.0), indicating no risk. Moreover, assessment of the long-term risk for ingestion of toxic metals indicated no risk (<10−6) based on the lifetime cancer risk (LCR). However, the LCR values of As and Cr were 5.3 × 10−6 and 2.5 × 10−6, respectively, demonstrating the most elevated LCR among the hazardous metals in terms of children’s exposure. Therefore, it is possible that children living in agricultural areas and participating in activities around the study area may be exposed to elevated concentrations of As and Cr.

Riverine Pesticides in an Agricultural Catchment in Northern Thailand: With Focus on Atrazine and Metabolites

“…While a substantial portion of the agriculture in northern Thailand relies on rain-fed practices, irrigation methods are employed to extend the growing season. The emergence of profitable crops has raised question about sustainability, especially when pesticides are incorporated. ,− Other agricultural depictions and pesticide-related research conducted in the northern highlands of mainland Southeast Asia hold relevance to the study site. ,,− While many of the highland farmers in these regions belong to ethnic minorities, the use of pesticides is widespread and common among all farmers regardless of race and location within catchments.…”