Trace elements in fluvial sediments of the Gandaki River Basin, Central Himalaya, Nepal: distribution, sources, and risk assessment
摘要
Himalayan river basins are crucial for water and sediment transport, supporting millions of people and influencing ecological health. However, the distribution, sources, and contamination levels of trace elements (TEs) in these regions remain poorly understood. This study assesses the spatial distribution, contamination levels, and sources of TEs in fluvial sediments of the Gandaki River Basin (GRB), Central Himalayas, Nepal.
Materials and methodsA total of 75 sediment samples from riverbed (R0), floodplain (R1), and terrace (R2) were analyzed. TE concentrations were measured, and contamination levels were evaluated using indices such as pollution load index (PLI), geo-accumulation index (Igeo), and enrichment factor (Ef). Principal component analysis (PCA) and correlation analysis were used to distinguish natural and anthropogenic sources of TEs.
Results and discussionTE concentrations varied, following the order: Ti > Ba > Sr > Rb > Zn > Cr > V > Li > Y > Ni > Cu > Pb > As > Sc > Co > Cs > U > Mo > Tl > Cd. Moderate to high contamination was observed for Cr, Cu, and Mo, with 12% of samples exceeding TEC and PEC for As and Cr, indicating potential environmental risks. Higher TE levels on the leeward (U-) side were linked to weathering of metal-rich materials and long-range transport processes.
ConclusionsThe study highlighted ecological risks from TE contamination in the GRB, stressing the need for pollution control, sustainable river basin management, and further research to mitigate environmental hazards.
Graphical abstract