Assessment of Lead (Pb) Leakage From Abandoned Mine Tailing Ponds to Klity Creek, Kanchanaburi Province, Thailand.

Abstract

In 2013, Klity Creek became the site of Thailand's first legally required remediation, 15 years after the spill of lead (Pb)‐contaminated mine tailings into the creek. Even today, nature cannot attenuate Pb‐contaminated sediment, arguably due to either high geological background Pb or continuous leakage of Pb from the unlined tailing ponds, upstream of the creek. In this study, four lines of evidence were used to reveal that the leakage from tailing ponds is primarily responsible for the long‐term Pb contamination. First, stable Pb isotope ratios (206Pb/207Pb and 208Pb/207Pb) were used to apportion sources between the tailings and geological background. The analysis of samples from the tailing ponds, geological background, and local zinc (Zn)‐Pb deposit revealed five different Pb sources (i.e., two distinct mine tailings, two different backgrounds, and a local Zn‐Pb deposit) in the area based on five unique isotope ratios. Using source apportionment analysis, Pb‐contaminated sediments in Klity Creek were consistent with tailings being the dominant source (30%–100%). Likewise, an analysis of Pb radionuclide (210Pb) revealed the Pb in the contaminated sediment was relatively new, 0–6.7 years old, suggesting that the Pb source was recent leakage from the tailing ponds rather than the 15‐year‐old tailing spill. Isotope evidence was supported by the elevated Pb‐contaminated seepage (0.30 ± 0.22 mg/L) from the tailing ponds and groundwater samples (up to 0.225 mg/L) collected from monitoring wells surrounding the tailing ponds. Consequently, proper management of Pb leakage from the tailing ponds is critical for successful Klity Creek remediation.