Abstract：Understanding the optical characteristics of chromophoric dissolved organic matter ( CDOM) could help to study dissolved organic matter ( DOM) cycling in aquatic ecosystems. In addition, environmental factors affected CDOM optical characteristics and resulted in influencing carbon cycle in aquatic environment. The spectral reflectance characteristics of riverine waters, CDOM absorption and fluorescent characteristic as well as environmental factors were analyzed for water samples collected in September 2013 and October 2014, respectively. Results showed that the water quality of Liaohe River watershed exhibited great variation. The concentrations of total nitrogen ( TN, 4.40 mg·L-1) and total dissolved chromium ( 0.0065 mg·L-1) exceeded the GB3838-2002 ( national quality standards for surface waters, China) standard for Class V waters of 2.0 mg·L-1 and 0.005 mg·L-1, respectively.Comparatively, samples with obvious characteristics of suspended sediments exhibited similar CDOM absorption curves while samples with obvious characteristics of chlorophyll a showed great differences. Values of S275-295 obtained in this study, ranging from 0.0163 to 0.0191 nm-1, were higher thanmany other rivers but lower than lakes and reservoirs. Relative lower molecular weight substances of CDOM in the East Liaohe River and the stem of Liaohe River were obtained compared with the other rivers. The SUVA254 showed that the aromaticity of CDOM in the East Liaohe River was higher while the West Liaohe River was lower than the others investigated. According to fluorescence index ( FI) , the index of recent autochthonous contribution ( BIX) and humification index ( HIX) , CDOM were mainly from terrestrial ( allochthonous) substances and DOM originating from higher plants. However, CDOM in Taizihe and Dalinghe were derived from autochthonous substances. The humic-like and protein-like peaks were all observed in fluorescence excitationemission matrices. Most samples exhibited fairly strong humic-like fluorophores ( peak A and C) and number of samples showed strong protein-like fluorophores ( peak B and T) at the same time. Redundancy analysis ( RDA) indicated that dissolved organic carbon, TN, total phosphorus, total alkalinity, total dissolved arsenic and mercury concentrations strongly correlated with parameters that explained optical characteristics ( p<0.05) and were the main factors affected CDOM characteristics.
Keyword：CDOM; optical characteristic; RDA; PCA; fluorescence index; fluorescence peaks;
【source】】Acta Scientiae Circumstantiae2018年04期
