Observations on carbon and nitrogen content of suspended matter in aheadwater stream in Hong Kong

Article type: Research Article

Authors: Peart, M.R. | GUAN, Dong-sheng

Affiliations: Department of Geography, University of Hong Kong, Hong Kong | Department of Environmental Science, Sun Yatsen (Zhongshan) University, Guangzhou 510275, China

Note: [] Corresponding author. E-mail: eesgds@zsu.edu.cn

Abstract: The total carbon(C) and total nitrogen(N) content of suspended matter in a small undisturbed headwater drainage basin in the New Territories of Hong Kong has been monitored. Mean C and N contents were 12.85% and 0.99% respectively for 132 samples. Samples collected under stableflow conditions had mean C and N contents of 12.81% and 1.06% respectively. Stormflow samples had mean C and N values of 12.86% and 0.97% respectively, which were very similar to the levels observed under stableflow conditions. The mean C:N ratios of 12.47 and 13.39 for stableflow and stormflow also reveal little difference according to hydrologic conditions. When all the data is considered little difference is observed in C and N according to the season. However, in winter there is a significant difference in C and N content between stable and stormflow samples. When C and N are plotted against water level the scattergraphs suggested that as stage increases the percentage of C and N in the suspended matter declines. Scattergraphs of C and N against suspended sediment concentration reveal a negative association. Comparison has been made between fresh leaf C, N and C/N ratio for trees and shrubs and the suspended matter. Fresh leaves do not appear to contribute significantly to suspended matter. The C/N ratio of suspended matter would also seem to exclude woody material and algae as sources of suspended matter.

Keywords: carbon, nitrogen, suspended matter, Hong Kong

Journal: Journal of Environmental Sciences, vol. 16, no. 4, pp. 533-538, 2004