title: Lead distribution and its potential risk to the environment: lesson learned from environmental monitoring of abandon mine.
abstract: There are many abandon and existing mines (tin, lead and zinc) in the mountainous areas of Thailand. Toxic elements including heavy metals such as lead (Pb), cadmium (Cd) and arsenic (As) have been released and transported from the mining sites to the adjacent landscape. In Thong Pha Phum District, Kanchanaburi Province, Thailand Pb contamination in the vicinity of the mine has occurred which could lead to potential health problems in downstream communities. To better understand current status of Pb contamination and accumulation in the surrounding environment and potential health impact, surface sediment, soil and plant samples were collected seasonally from representative monitoring sites along the aquatic track or flow regime. Potential health risk was determined using hazard quotient (HQ) as an index for local inhabitants who consume rice. Environmental monitoring illustrated that Pb concentrations in the surface sediment was as high as 869.4 mg kg(-1) dry weight and varied differently among stations sampled. Lead content in agricultural soil ranged between 137.8 to 613.5 mg kg(-1) dry weight and was inversely proportion to the distance from the point source. Moreover Pb was transported from the point source to down hill areas. At the highly polluted monitoring stations (S1, S2, and S3), concentrations of Pb exceeded the maximum allowable concentration for Pb in agricultural soil (300 mg kg(-1)) by 1.7-2 times. The Pb in soil was primarily associated with Fe/Mn oxides bound fraction (46-56%) followed by the organic bound fraction (25-30%). Lead uptake by plant varied and was species dependent. However root and tuber crops like cassava (19.92 mg Pb kg(-1) dry weight) and curcumin (3.25 mg Pb kg(-1) dry weight) could have removed Pb from the soil which suggest growing root crops in Pb contaminated soils should be avoided. However Cd, a co-contaminant at one of monitored stations (S4) yielded rice grain with Cd exceeding the maximum allowable concentration suggesting some potential health risk (HQ = 5.34) if people consume rice grown at this station. Overall result shows a low risk associated with Pb release into the environment.
authors.affiliation: School of Environmental, Resources and Development, Asian Institute of Technology, Pathumthani, Thailand.
authors.forename: Wanida
authors.initials: W
authors.lastname: Nobuntou
authors.forename: Preeda
authors.initials: P
authors.lastname: Parkpian
authors.forename: Nguyen Thi Kim
authors.initials: NT
authors.lastname: Oanh
authors.forename: Athapol
authors.initials: A
authors.lastname: Noomhorm
authors.forename: R D
authors.initials: RD
authors.lastname: Delaune
authors.forename: Aroon
authors.initials: A
authors.lastname: Jugsujinda
mesh_terms: D018556:Crops, Agricultural / Q000737:chemistry / Q000254:growth & development; D004784:Environmental Monitoring / Q000379:methods* / Q000706:statistics & numerical data; D005506:Food Contamination / Q000032:analysis; D019015:Geologic Sediments / Q000737:chemistry*; D006304:Health Status; D007854:Lead / Q000032:analysis* / Q000633:toxicity; D008906:Mining; D008962:Models, Theoretical; D012275:Oryza / Q000737:chemistry / Q000254:growth & development; D018570:Risk Assessment; D012621:Seasons; D012987:Soil / Q000032:analysis / Q000592:standards; D012989:Soil Pollutants / Q000032:analysis* / Q000633:toxicity; D013785:Thailand; D014872:Water Movements; D014874:Water Pollutants, Chemical / Q000032:analysis* / Q000633:toxicity
chemical_list: D012987:Soil; D012989:Soil Pollutants; D014874:Water Pollutants, Chemical; D007854:Lead