ECOLOGICAL RISK AND PHYTOREMEDIATION ASSESSMENT OF HEAVY METAL CONTAMINATION IN THALE NOI LAKE, THAILAND

Abstract

Thale Noi Lake is a part of the Songkhla Lagoon in Phatthalung Province, Thailand and is home to many different types of water animals. This research studies the levels and location of aluminum (Al), arsenic (As), and lead (Pb) in water, sediments, and aquatic plants. The study involved two aquatic plants, water lettuce (Pistia stratiotes) and water primrose (Ludwigia adscendens), which are macrophytes capable of absorbing metals from water and sediment. The analysis was conducted using ICP-OES on samples from four stations (ST01-ST04). The amount of Al, As, and Pb in the water at the four stations were found to be below the established maximum standards in Thale Noi Lake, indicating acceptable water quality. However, Al concentrations were highest in sediments, followed by Pb and As. Lead concentrations exceeded the sediment standard at all stations, and arsenic levels exceeded both USEPA and MacDonald standards. Statistical differences in heavy metal concentrations were confirmed by ANOVA followed by Tukey’s post hoc test. Al and As in water and sediment varied significantly among the stations, while differences were also observed between plant species and plant parts. High EF values for Pb and As at ST02 confirmed human influence, similar to Igeo results showing Pb contamination at all stations, while As remained unpolluted. The highest metal concentrations in ST01 were linked to the lowest sediment pH and DO. Both plants showed low BAF and BCF values, indicating limited metal accumulation from soil, but higher metal uptake from the water column, especially for arsenic and lead. Translocation factors remained below 1, suggesting metals were retained in roots, minimizing potential entry into the food chain. These findings support the potential of both species for phytoremediation, particularly in arsenic-and lead-contaminated waters.