Application of multi-monitoring methods to investigate the contamination levels and dispersion of Pb and Zn from tin mining in coastal sediments at Saphan Hin, Phuket, Thailand

Heavy metals have been detected in coastal regions, in the vicinity of former mining sites. The level of these heavy metals frequently exceed the safe limits in what represents an important aquatic source of food for human consumption. A thorough and conventional study into the levels of contamination in the suspected area is a costly but necessary exercise in order to inform any appropriate mitigating actions. This study demonstrates the benefits of integrating scientific investigating methods comprising chemical analysis using aqua regia and geo-electrical surveys, i.e., electrical resistivity imaging and induced polarization, to attain the approximate levels of contamination for both lateral and vertical landscapes in an efficient way. The demonstration to present the conformity and reliability of this joint methods is at Saphan Hin, situated on the southeastern coast of Phuket, Thailand. The site is located downstream of Bang-Yai canal; a potential intermediary carrying heavy metals especially Lead and Zinc from a number of mines where the nearest is approximately 4 km away. Saphan Hin is an important place marine fishery to supply to an increasing number of tourists to Phuket. The combined results from using all methods in this study are consistent in showing that the extent of the over-the-limit contamination can be found up to at least 200 m from the estuary, and with the decreasing depths from around 20 m to 50 cm at further distances from mainland, demanding urgent measures for the health of local people as well as tourists. A model to adapt these monitoring methods for implementation in operating mines is proposed as an early warning system to prevent any leakage probably occurring under normal conditions. (C) 2019 Elsevier Ltd. All rights reserved.