In order to understand the transport and humification processes of dissolved organic matter（DOM） within sediments of a semi-arid floodplain at Rifle,Colorado,fluorescence excitation–emission matrix（EEM） spectrosc...In order to understand the transport and humification processes of dissolved organic matter（DOM） within sediments of a semi-arid floodplain at Rifle,Colorado,fluorescence excitation–emission matrix（EEM） spectroscopy,humification index（HIX） and specific UV absorbance（SUVA） at 254 nm were applied for characterizing depth and seasonal variations of DOM composition.Results revealed that late spring snowmelt leached relatively fresh DOM from plant residue and soil organic matter down into the deeper vadose zone（VZ）.More humified DOM is preferentially adsorbed by upper VZ sediments,while non-or lesshumified DOM was transported into the deeper VZ.Interestingly,DOM at all depths undergoes rapid biological humification process evidenced by the products of microbial by-product-like（i.e.,tyrosine-like and tryptophan-like） matter in late spring and early summer,particularly in the deeper VZ,resulting in more humified DOM（e.g.,fulvic-acid-like and humic-acid-like substances） at the end of year.This indicates that DOM transport is dominated by spring snowmelt,and DOM humification is controlled by microbial degradation,with seasonal variations.It is expected that these relatively simple spectroscopic measurements（e.g.,EEM spectroscopy,HIX and SUVA） applied to depth-and temporally-distributed pore-water samples can provide useful insights into transport and humification of DOM in other subsurface environments as well.展开更多
The concentrations of the particulate organic carbon (POC) and its isotopic compositions inthe freshwater in the lower reaches of the Huanghe River were observed for one year period.The annualfluxes of the POC and tot...The concentrations of the particulate organic carbon (POC) and its isotopic compositions inthe freshwater in the lower reaches of the Huanghe River were observed for one year period.The annualfluxes of the POC and total carbon of the Huanghe River entering seas were estimated,in combination withthe available data on carbon in the dissolved state in literature.For this study 295 water samples and 115sediment ones from 118 stations were collected on three separate cruises to the Huanghe Estuary and morethan 400 organic carbon isotope data were obtained.After the comprehensive study a new model was con-structed on the dispersion of fine-grained suspended matter entering seas from the Huanghe River in combi-nation with contents of suspended matter,concentrations of POC in water samples and grain size parame-ters,contents of organic carbon in sediment samples.展开更多
基金partially performed at the Molecular Foundry,Lawrence Berkeley National Laboratorysupported as part of the Sustainable Systems Scientific Focus Area program at Lawrence Berkeley National Laboratorysupported by the U.S.Department of Energy,Office of Science,Office of Biological and Environmental Research,Subsurface Biogeochemical Research Program,through Contract No.DE-AC02-05CH11231 between Lawrence Berkeley National Laboratory and the U.S.Department of Energy
文摘In order to understand the transport and humification processes of dissolved organic matter（DOM） within sediments of a semi-arid floodplain at Rifle,Colorado,fluorescence excitation–emission matrix（EEM） spectroscopy,humification index（HIX） and specific UV absorbance（SUVA） at 254 nm were applied for characterizing depth and seasonal variations of DOM composition.Results revealed that late spring snowmelt leached relatively fresh DOM from plant residue and soil organic matter down into the deeper vadose zone（VZ）.More humified DOM is preferentially adsorbed by upper VZ sediments,while non-or lesshumified DOM was transported into the deeper VZ.Interestingly,DOM at all depths undergoes rapid biological humification process evidenced by the products of microbial by-product-like（i.e.,tyrosine-like and tryptophan-like） matter in late spring and early summer,particularly in the deeper VZ,resulting in more humified DOM（e.g.,fulvic-acid-like and humic-acid-like substances） at the end of year.This indicates that DOM transport is dominated by spring snowmelt,and DOM humification is controlled by microbial degradation,with seasonal variations.It is expected that these relatively simple spectroscopic measurements（e.g.,EEM spectroscopy,HIX and SUVA） applied to depth-and temporally-distributed pore-water samples can provide useful insights into transport and humification of DOM in other subsurface environments as well.
基金the National Natural Science Foundation of China.
文摘The concentrations of the particulate organic carbon (POC) and its isotopic compositions inthe freshwater in the lower reaches of the Huanghe River were observed for one year period.The annualfluxes of the POC and total carbon of the Huanghe River entering seas were estimated,in combination withthe available data on carbon in the dissolved state in literature.For this study 295 water samples and 115sediment ones from 118 stations were collected on three separate cruises to the Huanghe Estuary and morethan 400 organic carbon isotope data were obtained.After the comprehensive study a new model was con-structed on the dispersion of fine-grained suspended matter entering seas from the Huanghe River in combi-nation with contents of suspended matter,concentrations of POC in water samples and grain size parame-ters,contents of organic carbon in sediment samples.
