The ecological complexity of the Thai-Laos Mekong River: II. Metals and polyaromatic hydrocarbons (PAHs) monitoring, modelling and environmental fate

• Published in: Journal of environmental science and health. Part A, Toxic/hazardous substances & environmental engineering Toxic/hazardous substances & environmental engineering, 2010-11, Vol.45 (13), p.1674-1680
• Main Authors: Keenan, Helen E., Bangkedphol, Sornnarin, Sakultantimetha, Arthit, Songsasen, Apisit
• Format: Article
• Language: English
• Subjects: Animals; Applied sciences; bioconcentration factor; biomagnifications; Cadmium - analysis; Cadmium - toxicity; chronic value; Continental surface waters; Ecology; Environmental Monitoring - methods; Environmental Monitoring - standards; Environmental Monitoring - statistics & numerical data; Environmental quality; Environmental science; Exact sciences and technology; Fishes - growth & development; Humans; Laos; Lead - analysis; Lead - toxicity; lethal concentration 50; Lethal Dose 50; Manganese - analysis; Manganese - toxicity; metal; Metals; Metals, Heavy - analysis; Metals, Heavy - toxicity; Models, Theoretical; Natural water pollution; octanol-water partition coefficient; organic carbon partition coefficient; PAHs; Pollution; Polycyclic aromatic hydrocarbons; Polycyclic Aromatic Hydrocarbons - analysis; Polycyclic Aromatic Hydrocarbons - toxicity; Quality; Rivers; Rivers - chemistry; sediment-water partition coefficient; Thailand; Water Pollutants, Chemical - analysis; Water Pollutants, Chemical - toxicity; Water Supply - standards; Water treatment and pollution
• ISSN: 1093-4529; 1532-4117
• DOI: 10.1080/10934529.2010.513208

The Mekong is an essential source of water and protein for the denizens of Thai Laos countries. It is hypothesized that pollution may be adversely affecting the water and sediment quality, which threatens the short and long-term use of this major river system. This directly impacts on the health and population of the aquatic life and ultimately human health and the economy for both countries is affected. The quality of the river can be assessed from various chemical and physical parameters, such as PAHs and metals content of both the water and the sediment. The introduction of Environmental Quality Standards (EQS) allows comparison of the values obtained with the guidelines. Furthermore the modelling program EPISUITE was used to determine the environmental partitioning of pollutants within the different environmental compartments. Using the data produced for PAHs and metals the experimental model was compared to the default model. This involved experimentally measuring the log K oc for Mekong sediments and from this determining the log K ow . High availability in sediment of pollutants may lead to greater biomagnification in bethnic fish, which may then be hazardous for human consumption even if it is safe for the species that is accumulating pollutants. The potential for this is shown by the calculated accumulation in biota C bio values exceeding both the Chronic value (ChrV) and Lethal Concentration 50 (LC 50 ) for fish in the Mekong River. When compared to the EQS guidelines the amount of some PAHs, cadmium and lead in sediment were above the lowest effect level but below the severe effect level.