| This paper systematically studied the distribution,composition and source of dissolved organic matter(DOM)in surface water,soil and sediment in Huainan section of Huaihe River Basin.UV-Vis absorption spectrum(UV-Vis)and excitation and emission matrix(EEMs)were used as technical means for DOM spectral characterization.The distribution and composition of DOM in surface water,soil and sediment were explored by parallel factor analysis(PARAFAC)and fluorescence regional integration(FRI).At the same time,combined with water quality parameters and spectral data,the influence of water quality on DOM was analyzed in depth,and the correlation between DOM and the release of dissolved organic phosphorus(DOP)and soluble reactive phosphorus(SRP)caused by sediment disturbance was studied.In order to provide a scientific basis for the study of DOM produced by agricultural non-point sources.The main results are as follows :(1)Three chemical components(humic acid-like C1 and C2,protein-like C3)were isolated from water DOM by parallel factor analysis.The proportion of C1+C2components(63.01%-71.53%)was higher than that of C3(28.47%-36.99%).The humification degree of DOM in the four types of water bodies is low,which is affected by both microbial and terrestrial sources.The DOM of the four types of water bodies is mainly composed of tryptophan-like(region II)and fulvic acid-like(region III)in the ultraviolet region,while the proportion of substances represented by regions I,IV and V is relatively small.The regression analysis of the regional integral components of DOM and water quality indicators shows that the material content of the five regions is closely related to water quality indicators such as nitrogen and phosphorus.(2)Inverse distance weighted interpolation analysis showed that the content of dissolved organic carbon(DOC)in the north side of Machang Reservoir was higher than that in the south side in summer,while the opposite was true in winter.The aromaticity and hydrophobicity of DOM in reservoir water in different seasons are closely related,and the degree of humification is low,which is affected by both microbial and terrestrial sources.Two humic-like substances C1 and C2 and a protein-like substance C3 were decomposed from the water of Machang Reservoir by parallel factor analysis.Among them,C1 and C2 had strong homology,and total dissolved nitrogen(TDN)and total dissolved phosphorus(TDP)were more closely related to tryptophan-like proteins.(3)The content of DOC in soil was woodland>farmland>grassland>vegetable land.The content of DOC in woodland soil was significantly higher than that in other land use types,and the content of aromaticity,molecular weight and hydrophobic organic matter in woodland soil was also significantly higher than that in other three soils.Three components(humic-like C1,tyrosine-like C2,and tryptophan-like C3)were extracted from soil DOM by parallel factor analysis.The proportion of C2+C3components was greater than that of C1 components.All soil DOM were affected by both exogenous and endogenous inputs,and the degree of humification was weak,mainly fulvic acid.(4)The release kinetics of SRP and DOP in the sediment extract can be well fitted by the second-order kinetic model.SRP is mainly derived from terrestrial input,and DOP is mainly composed of small molecular organic phosphorus compounds.Although the release of SRP was significantly greater than that of DOP with the increase of extraction time,the correlation between DOP and DOM was closer.The correlation between the concentration of DOP and the fluorescence intensity integral area of regions I,II and III was significantly higher than that of SRP.Sediment DOM is affected by microbial metabolism and terrestrial input.Among them,the source of DOM in ditch sediments tends to be microbial metabolism,and the autogenic characteristics are strong.The humification degree of sediment DOM is weak,and the humification degree of ditch sediment DOM is lower than that of other sediments.The proportion of regional material content of sediment DOM was generally characterized by protein-like substances(P1+P2+P4)greater than humus-like substances(P3+P5),and the proportion of protein-like substances in ditch sediments was the highest,reaching 74.36%.Figure [36] Table [20] Reference [158]... |
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