title: Bioavailability of riverine dissolved organic carbon and nitrogen in the Heilongjiang watershed of northeastern China.
abstract: The bioavailabilities of dissolved organic carbon (DOC) and dissolved organic nitrogen (DON) were examined in eight sampling stations of the Heilongjiang watershed, located in Heilongjiang Province, northeast China. Water samples were incubated for 55 days at 20 °C, and the decreases in the DOC and DON concentrations were measured during the laboratory incubations. The experiments showed that bioavailable DOC (BDOC) accounted for 15-30% of DOC and bioavailable DON (BDON) accounted for 29-57% of DON. DOM bioavailability was higher for DON compared to DOC, suggesting that DON was more bioavailable and had a faster turnover than DOC in the Heilongjiang watershed. Furthermore, the percent of bioavailable DOC (%BDOC) was significantly related to SUVA254, not the DOC concentration, suggesting that the chemistry composition of DOM played a more important role in affecting its bioavailability compared to the DOM concentration. In addition, significant negative correlations were observed between the initial DOC/DON ratios and the percent of bioavailable DOM fractions (%BDOC and %BDON), especially for %BDON, implying that low C/N molecules or N-rich compounds may be preferentially utilized by microbes. Graphical Abstract DOC concentrations of eight sampling sites, microbial decomposition of DOC over 55 days, % bioavailable DOC of eight sampling sites, DOM chemical composition of eight sampling sites, demonstrated chemical composition influence on DOM bioavailability.
authors.affiliation: College of Life Science, Northeast Agricultural University, Harbin, 150030, China.
authors.forename: Jianhong
authors.initials: J
authors.lastname: Shi
authors.affiliation: College of Life Science, Northeast Agricultural University, Harbin, 150030, China.
authors.forename: Hongyang
authors.initials: H
authors.lastname: Cui
authors.affiliation: Heilongjiang Province Environmental Monitoring Centre, Harbin, 150056, China.
authors.forename: Liming
authors.initials: L
authors.lastname: Jia
authors.affiliation: College of Life Science, Northeast Agricultural University, Harbin, 150030, China.
authors.forename: Linlin
authors.initials: L
authors.lastname: Qiu
authors.affiliation: College of Life Science, Northeast Agricultural University, Harbin, 150030, China.
authors.forename: Yue
authors.initials: Y
authors.lastname: Zhao
authors.affiliation: College of Life Science, Northeast Agricultural University, Harbin, 150030, China. weizm691120@163.com.|, No. 59, Mucai Street, Xiangfang District, Harbin, 150030, China. weizm691120@163.com.
authors.forename: Zimin
authors.initials: Z
authors.lastname: Wei
authors.affiliation: College of Life Science, Northeast Agricultural University, Harbin, 150030, China.
authors.forename: Junqiu
authors.initials: J
authors.lastname: Wu
authors.affiliation: College of Life Science, Northeast Agricultural University, Harbin, 150030, China.
authors.forename: Xin
authors.initials: X
authors.lastname: Wen
mesh_terms: D002244:Carbon / Q000032:analysis*; D002681:China; D004784:Environmental Monitoring; D009584:Nitrogen / Q000032:analysis*; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D014874:Water Pollutants, Chemical; D002244:Carbon; D009584:Nitrogen
keywords: Aromaticity; Bioavailability; Dissolved organic carbon (DOC); Dissolved organic nitrogen (DON); Heilongjiang watershed