Source And Characterization Of Dissolved Organic Matter(DOM) In Jinpen Reservoir

Jinpen Reservoir is located in the Heihe River Basin of Xi'an and a single-cycle gorge deep-water reservoir.The lack of oxygen and endogenous pollution caused by stratification of water and rainfall runoff have a significant impact on water quality,which directly affects the quality and safety of drinking water sources.Therefore,the three-dimensional fluorescence spectroscopy-parallel factor analysis method and UV-visible absorption spectroscopy were used to analyze the distribution characteristics and sources of DOM in the water bodies,interstitial water and sediment along the Jinpen Reservoir.And the relationship between sediment DOM and nitrogen in sediments was discussed.The impact of runoff input on DOM of the reservoir was focused on.The main conclusions of this paper are as follows:?1?By using EEMs-PARAFAC,the fluorescence components of fulvic acid-like C1,tryptophan-like C2 and humic acid-like C3 were found in the water of Jinpen Reservoir.Through the analysis of the fluorescence spectrum indicators?FI,BIX,HIX?,it is concluded that the source of DOM in Jinpen Reservoir has both endogenesis and terrestrial sources.This feature originates from the geomorphic characteristics and hydrological conditions of the reservoir.?2?The characteristics of DOM in reservoir water have significant temporal and spatial changes.In terms of time,from the winter of 2016 to the fall of 2017,the DOM concentration of water bodies is the largest in winter,the lowest in spring,and it has risen in summer,but remained low,and the fluorescence intensity in autumn increases to a higher level.DOM of the vertical water body has no significant difference in autumn,winter and spring,but there is a vertical difference in summer in space;along the way from the upstream to the main reservoir area,DOM gradually decreases.?3?Rainfall runoff is the main source of DOM of reservoir.In early June,heavy runoff water carried a large amount of granular nutrient organic material and silt dive into the form of gravity flow.The flow pattern changed from the underlying subsurface flow in the river area to the transitional interval laminar flow and eventually mixed with the water in the main reservoir area.,which caused a short-term high load on the main library DOM?4?There is a significant reservoir concentration gradient of DOM between interstitial water of sediments and overlying water in reservoir.The sediment DOM is easily released into water bodies under the conditions of water disturbance,microbial action and so on.The interstitial water DOM content and the degree of humification gradually increased with depth.?5?Through analysing the absorption index a₃₅₀,the spectral slopes S_275-295,S_350-400,and the spectral slope ratio S_R,it shows that DOM concentration of sediments extracted from the upstream to the main reservoir shows a trend of decreasing first and then increasing.This is due to the gradual deposition of organic particles from upstream to downstream and enrichment in the main reservoir area.The content of DOM components in sediments shows a high correlation with sediment nitrogen.Degradation of sediment DOM is one of the major sources of sediment nitrogen.