Heavy Metal Contamination of Surface Waters in Mae Moh, Lampang, Thailand

Abstract

The Mae Moh Lignite Mine and Power Plant is one of the largest energy production complexes in Thailand, with a total generating capacity of 2,625 megawatt. While lignite coal is viewed as an indispensible source of energy for Thailand, pollution and health impacts arising from coal combustion has generated much public and academic concern. My study aims to measure the surface water quality of water sources in Mae Moh District, Lampang, Thailand. Water pollution in Mae Moh is less studied as compared to air pollution, and no prior study has considered the water quality of sources outside of the Mae Moh Power Plant that are accessible to the general public. The key objective of my study is to determine whether the concentrations of heavy metals in Mae Moh District’s surface waters is a potential threat to human health and the natural environment. Inductively Coupled Plasma Mass Spectrometry (ICP-MS) was used to measure arsenic, cobalt, chromium, iron, lead and zinc concentrations, and compared against the threshold concentrations set by relevant environmental and health agencies. A total of 32 water samples were taken from canals, reservoirs, wells, stream tributaries, settling ponds and sumps in Mae Moh District. All six heavy metals were found to be present in the waters of Mae Moh District. However, arsenic was the only element that was found at concentrations 3 exceeding threshold values (0.01 mg/L or 10 ?g/L). Of the four water sources with arsenic concentrations that exceeded threshold values, three of them were settling ponds and sumps that belong to the Mae Moh Power Plant’s water network. Villagers from the Mae Moh District are unlikely to be at risk of arsenic poisoning since they do not access the wastewaters in Mae Moh Power Plant, and treated or filtered water is their main source of water for drinking and domestic usage.