Determination of levels of Mn, As, and other metals in water, sediment, and biota from Phayao Lake, Northern Thailand, and assessment of dietary exposure

Abstract

This study was undertaken to determine levels of contamination of toxic metals in water, sediment, and consumed fishery products from Phayao freshwater lake located in northern Thailand, which is a major water resource for drinking water, agriculture, and household use. Concentrations of Mn, As, and other metals were determined in water, sediment, fish tissues (Puntius gonionotus) and pond snails (Filopaludina martensi). Sampling was carried out in 3 periods (February, May, and August) in 2005. Metal analysis was performed by using inductively coupled plasma mass spectrometer (ICP-MS). Concentrations of Mn and As in lakewater ranged from 40–382 and 0.68–8.79 μ g L^{− 1} whereas the USEPA (Mn) and WHO (As) guidelines for drinking water are 50 and 10 μ g L^{− 1}, respectively. Concentrations of some metals (Al, Cr, Mn, and Fe) in water were found to be higher in the area where water flowed into the lake from a small river than in other areas. The highest metal concentrations were found in the period of the dry season (May 2005). Among different sampling sites, the patterns of metal accumulations were different. Estimated fishery product consumption from the lake was calculated and the results indicated that the concentrations of metals in these products were lower than the recommended average daily dietary intake. Therefore, the consumption of fish and pond snail from this water resource may not pose a risk of metal toxicity. However, monitoring of the levels of Mn and As in lakewater should be carried out routinely so that appropriate prevention of contamination from these toxic metals can be implemented.

Keywords:

• Metals
• ICP-MS
• Phayao Lake
• Thailand
• freshwater
• sediment

Acknowledgments

This study was supported by the Inter University Program on Environmental Toxicology, Technology and Management, Asian Institute of Technology, Mahidol University and Chulabhorn Research Institute. The authors would like to thank Ms. Sumontha Nookabkaew for technical support on ICP-MS instrument and Ms. Sunisa Charoenphan for lab assistance.

Notes

* = information value.

^a Abundant metals

^b trace metals

^c toxic metals.

^a Abundant metals

^b trace metals

^c toxic metals. Metal contents analyzed in dry weight from the sediment. A to J represent sampling sites. For detailed description see Table 1.

^a Abundant metals

^b trace metals

^c toxic metals.

^a Estimated dietary intake based on 70 kg human body weight (COT, 2003).

^b Recommended dietary allowance (RDAs)/adequate daily dietary intake (http://www.nap.edu).

^c 23.6 kg per year of fish consumption rate in Thailand. (http://www.fao.org/fi/fcp/en/THA/profile.htm).

^d Estimated consumption rate at 5 kg per year per capita in Thailand.