ITP Prof. ZHANG Fan will host the 41st academic frontier seminar, inviting Dr. Tao Yan from University of Hawai'i to share with us his latest research efforts and achievement. See http://www.cee.hawaii.edu/persons/yan/yan.htm for more about Dr. Tao Yan and his research interest.

Your participation and involvement in the discussion are warmly welcome!

Report: Effects of Land Uses on the Contamination of Water, Soil, and Sediment in Watersheds of a Tropical Island

Presenter: Tao Yan, Assistant Professor of Civil and Environmental Engineering, University of Hawai’I at Manoa

Venue: meeting room on the second floor of ITP office buidling

Time: 3.00 pm, Friday, 24 June 2011

Abstract:

Human activities can significantly change the landscape and alter indigenous environmental conditions. In this talk, we will discuss the effects of different land uses on (1) the bacteriological quality of water and soil, and (2) concentrations of polycyclic aromatic hydrocarbons (PAHs) in stream sediments, on the Island of Oahu, Hawaii. To understand how urbanization affects water bacteriological quality, we monitored the concentration dynamics of several fecal indicator bacteria (FIBs), including E. coli, enterococci, and C. perfringens, in both forest and urban sections of the Manoa Stream over an eight-month period. Significantly higher levels of FIBs were observed in the urban stream water than that of the rainforest section. In contrast, no significant difference in E. coli concentration was observed in soils affected by the two land uses. Rep-PCR DNA fingerprinting technique was used to investigate the genetic variation of E. coli. High spatial and temporal variations in E. coli genotypes were observed in the Manoa watershed, but there was no significant difference in E. coli genotypes with respect to land uses. The second part of the talk will focus on the effects of land uses on the concentrations of polycyclic aromatic hydrocarbons (PAHs) in stream sediments. We sampled 28 coastal stream sediments affected by urban residential, urban industrial, and agricultural activities (including forest), and found that the average concentrations of PAHs increased in the order of agricultural, urban residential, and urban industrial land uses. The fractional concentrations of 16 PAHs and specific PAH ratios indicated that PAHs sources in the urban residential stream sediments are most likely of petroleum origin, while PAHs in the urban residential and agricultural stream sediments most likely came from combustion activities.