title: Characterization of dissolved organic nitrogen in wet deposition from Lake Erhai basin by using ultrahigh resolution FT-ICR mass spectrometry.
abstract: Dissolved Organic Nitrogen (DON) of wet deposition in Erhai basin (EWD) was characterized at the molecular level by using electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI FT-ICR MS). The structure and composition of DON were investigated by the combined ESI FT-ICR MS, UV-Vis absorbance and fluorescence techniques. The FT-ICR MS measurements indicate that a large (∼790) number of organic species present in the wet deposition, in which DON account for 18.3%, with most of DON containing a single nitrogen atom. The typical relative molecular mass of the DON species was found to be in the range of 200-400 Da. Approximately 57.2% of DON species are highly unsaturated (DBE (Double Bond Equivalent) > 5) with the nitrogen- and sulfur-containing species, which are probably represented mainly by active nitrooxy organosulfates, accounting for ∼ 19.3% of the total DON. The low average SUVA254 and A253/A203 values (0.02 and 0.06, respectively), indicates that the aromaticity of the EWD samples is particularly weak. The average values of E2/E3 and E4/E6 in the EWD samples were 6.84 and 1.84, respectively. This is a clear indication of the low degree of humification of EWD samples, in agreement with ESI FT-ICR MS measurements. Our study demonstrates that multiple experimental techniques combined with FT-ICR MS, UV-Vis absorbance and fluorescence can be efficiently used for in-depth studying the DON at the molecular level. Thus it allows us to achieve a deep and insightful understanding of the DON structure and composition.
authors.affiliation: Research Center of Lake Environment, Chinese Research Academy of Environment Sciences, Beijing, China; State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing, China; College of Resources, Environment and Tourism, Capital Normal University, Beijing, China.
authors.forename: Shuang
authors.initials: S
authors.lastname: Feng
authors.affiliation: Research Center of Lake Environment, Chinese Research Academy of Environment Sciences, Beijing, China; State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing, China.
authors.forename: Li
authors.initials: L
authors.lastname: Zhang
authors.affiliation: Research Center of Lake Environment, Chinese Research Academy of Environment Sciences, Beijing, China; State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing, China. Electronic address: wangshengruia@126.com.
authors.forename: Shengrui
authors.initials: S
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing, China; Atmospheric Science Research Center, State University of New York at Albany, 251 Fuller Road, Albany, NY 12203, USA; Department of Applied Mathematics, Moscow State University of Technology "Stankin", Vadkovsky per. 1, Moscow 127055, Russia.
authors.forename: Alexey B
authors.initials: AB
authors.lastname: Nadykto
authors.affiliation: State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing, China; Atmospheric Science Research Center, State University of New York at Albany, 251 Fuller Road, Albany, NY 12203, USA.
authors.forename: Yisheng
authors.initials: Y
authors.lastname: Xu
authors.affiliation: State Key Laboratory of Heavy Oil Processing, China University of Petroleum, Beijing 102249, China.
authors.forename: Quan
authors.initials: Q
authors.lastname: Shi
authors.affiliation: State Key Laboratory of Heavy Oil Processing, China University of Petroleum, Beijing 102249, China.
authors.forename: Bin
authors.initials: B
authors.lastname: Jiang
authors.affiliation: Research Center of Lake Environment, Chinese Research Academy of Environment Sciences, Beijing, China; State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing, China.
authors.forename: Weibin
authors.initials: W
authors.lastname: Qian
mesh_terms: D002681:China; D004784:Environmental Monitoring; D004785:Environmental Pollutants / Q000032:analysis* / Q000737:chemistry; D005583:Fourier Analysis; D060106:Lakes; D009584:Nitrogen / Q000032:analysis* / Q000737:chemistry; D011891:Rain / Q000737:chemistry*; D021241:Spectrometry, Mass, Electrospray Ionization; D013455:Sulfur / Q000032:analysis
chemical_list: D004785:Environmental Pollutants; D013455:Sulfur; D009584:Nitrogen
keywords: Characterization; DON; ESI FT-ICR MS; Erhai; Wet deposition