Water resources in East Asia are considered particularly vulnerable to climate variability and extremes due to strong hydrologic variability inherent in the monsoon climate and rising water demand resulting from rapid economic growth. To obtain a better understanding of the current status and climate-induced risks concerning surface water quality in East Asia, seasonal and spatial variations in surface water quality were compared among 11 watersheds in eight countries during typical dry and wet periods from 2006 to 2008. While concentrations of dissolved ions tended to be higher during dry periods, concentrations of suspended sediments and dissolved organic matter were significantly higher during wet periods at most sampling locations. Metals with low solubility showed higher total concentrations during wet periods and had strong positive relationships with suspended sediment concentrations. Metals with high partitioning into the dissolved phase exhibited higher concentrations during dry periods at many sites. Seasonal and spatial patterns were distinct along the Lower Mekong River, including much higher monsoonal concentrations of sediment-associated metals and relatively high dry-season concentrations of dissolved As along upper reaches. The results suggest that rainfall variability is crucial in understanding seasonality and climate-induced risks concerning surface water quality in East Asia.
Bibliographical noteFunding Information:
Water sampling campaigns in eight countries were conducted as part of an international research project funded by the APN (Asia-Pacific Network for Global Change Research) through START (ARCP2008-04CMY-Park), with additional funding provided by the UNU & GIST Joint Programme on Science and Technology for Sustainability. The work conducted in Korea by JH Park was supported by Korea Forest Service (‘Forest Science & Technology Project’ S210810L010110) and the National Research Foundation of Korea funded by the Korea Government (ERC 2009-0093460; KRF-2007-313-F00033). We thank Prof. Jung-Soo Lee for drawing the site map, Sei-Young Kim for ICP-MS analysis, and numerous other students and research staff for their assistance in sample collection and analysis. Part of chemical analysis was conducted at the Central Laboratory of Kangwon National University.
- East Asia
- Mekong River
- Rainfall variability
- Surface water quality
- Suspended sediments
- Trace metals