title: Distribution and spectral characteristics of chromophoric dissolved organic matter in a coastal bay in northern China.
abstract: The absorption spectra of chromophoric dissolved organic matter (CDOM), along with general physical, chemical and biological variables, were determined in the Bohai Bay, China, in the springs of 2011 and 2012. The absorption coefficient of CDOM at 350 nm (a350) in surface water ranged from 1.00 to 1.83 m⁻¹ (mean: 1.35 m⁻¹) in May 2011 and from 0.78 to 1.92 m⁻¹ (mean: 1.19 m⁻¹) in April 2012. Little surface-bottom difference was observed due to strong vertical mixing. The a350 was weakly anti-correlated to salinity but positively correlated to chlorophyll a (Chl-a) concentration. A shoulder over 260-290 nm, suggestive of biogenic molecules, superimposed the overall pattern of exponentially decreasing CDOM absorption with wavelength. The wavelength distribution of the absorption spectral slope manifested a pronounced peak at ca. 300 nm characteristic of algal-derived CDOM. All a250/a365 ratios exceeded 6, corresponding to CDOM molecular weights (Mw) of less than 1 kDa. Spectroscopically, CDOM in the Bohai Bay differed substantively from that in the Haihe River, the bay's dominant source of land runoff; photobleaching of the riverine CDOM enlarged the difference. Results point to marine biological production being the principal source of CDOM in the Bohai Bay during the sampling seasons. Relatively low runoff, fast dilution, and selective photodegradation are postulated to be among the overarching elements responsible for the lack of terrigenous CDOM signature in the bay water.
authors.affiliation: College of Marine Science & Engineering, Tianjin University of Science & Technology, Tianjin 300457, China. Electronic address: liguij@tust.edu.cn.
authors.forename: Guiju
authors.initials: G
authors.lastname: Li
authors.affiliation: College of Marine Science & Engineering, Tianjin University of Science & Technology, Tianjin 300457, China.
authors.forename: Jing
authors.initials: J
authors.lastname: Liu
authors.affiliation: College of Marine Science & Engineering, Tianjin University of Science & Technology, Tianjin 300457, China.
authors.forename: Yulan
authors.initials: Y
authors.lastname: Ma
authors.affiliation: College of Marine Science & Engineering, Tianjin University of Science & Technology, Tianjin 300457, China.
authors.forename: Ruihua
authors.initials: R
authors.lastname: Zhao
authors.affiliation: College of Marine Science & Engineering, Tianjin University of Science & Technology, Tianjin 300457, China.
authors.forename: Suzheng
authors.initials: S
authors.lastname: Hu
authors.affiliation: College of Marine Science & Engineering, Tianjin University of Science & Technology, Tianjin 300457, China.
authors.forename: Yijie
authors.initials: Y
authors.lastname: Li
authors.affiliation: College of Marine Science & Engineering, Tianjin University of Science & Technology, Tianjin 300457, China.
authors.forename: Hao
authors.initials: H
authors.lastname: Wei
authors.affiliation: College of Marine Science & Engineering, Tianjin University of Science & Technology, Tianjin 300457, China; Institut des sciences de la mer de Rimouski, Université du Québec à Rimouski, Rimouski, Québec G5L 3A1, Canada. Electronic address: huixiang_xie@uqar.ca.
authors.forename: Huixiang
authors.initials: H
authors.lastname: Xie
mesh_terms: D002681:China; D009792:Oceans and Seas; D012623:Seawater / Q000737:chemistry*; D013057:Spectrum Analysis / Q000379:methods*; D014874:Water Pollutants, Chemical / Q000737:chemistry*
chemical_list: D014874:Water Pollutants, Chemical
keywords: Bohai Bay; CDOM; Molecular weight; Photobleaching; Spectroscopic properties