Abstract:

This study used fluorescence emission spectra,fluorescence excitationemissionmatrix spectroscopy (EEMs) and UVVis absorbance spectra to access the spectra characteristics of dissolved organic matter (DOM) in the sediments sampled in the Yangtze River around Chongqing urban area. Absorption index E2/E3 (absorbance at 250 nm to 365 nm) was observed to ensure the composition of DOM in the sediments.Meanwhile,by determining the fluorescence index 〖WTBX〗f〖WTBZ〗450/〖WTBX〗f〖WTBZ〗500 at 370 nm with fluorescence emission spectra and analysising the EEM’s fingerprint feature,the source and spatial distribution rule of DOM were further evaluated. From the results,the value of fluorescence index 〖WTBX〗f〖WTBZ〗450/〖WTBX〗f〖WTBZ〗500 (142-163) indicated that DOM in the sediments might derive from microbial and terrestrial sources with a predominantly terrestrial origins character. The value of E2/E3 ranged from 202 to 304.Four kinds of fluorescence peaks of DOM in the sediments were identified,including a mayor component humiclike materials,other proteinlike materials, fulvic materials and microbial byproducts.The higher fluorescence value presented in the chonggang and cuntan sampling station,the lower fluorescence value presented in egongyan and yudong sampling station, and the fluorescence value showed the trends of updownup in spatial distribution along the Yangtze River of Chongqing section