冰封期前后河流底泥中溶解性有机物组分的荧光特性的变化

以沈阳市新开河为研究对象,考察了冰封期前、后河流底泥中溶解性有机物(DOM)组分荧光特性的变化.按照DOM在XAD树脂上的吸附特性将其分为5个部分:疏水性有机酸(HPO-A)、疏水性中性有机物(HPO-N)、过渡亲水性有机酸(TPI-A)、过渡亲水性中性有机物(TPI-N)和亲水性有机物(HPI).结果表明:HPO-A是河流底泥中的主要DOM组分,在冰封期前、后分别占溶解性有机碳(DOC)的41.2%~69.5%和38.9%~63.9%.冰封期前河流底泥中的DOM及HPO-A、HPI的DOC值均高于冰封期后.三维荧光光谱结果显示,冰封期前、后河流底泥DOM组分中含有类腐殖酸荧光物质,类富里酸荧光物质,类芳香族蛋白质荧光物质和类溶解性微生物代谢产物荧光物质,并且类芳香族蛋白质荧光物质在各DOM组分中的含量最高.冰封期后HPO-A、HPI中荧光物质的含量低于冰封期前.同步荧光光谱结果显示,在冰封期河流底泥DOM组分中激发波长分别为285~295 nm和330~350 nm的荧光物质向水体释放,导致其在底泥DOM组分中相对含量的显著降低.

Changes in fluorescence characteristics of dissolved organic matter fractions in the sediments of river before and after the icebound season

The changes in fluorescence characteristics of dissolved organic matter (DOM) fractions in the sediments of the Xinkaihe River in Shenyang before and after the icebound season were E_xamined. DOM was fractionated using XAD resins into five fractions: hydrophobic acid (HPO-A), hydrophobic neutral (HPO-N), transphilic acid (TPI-A), transphilic neutral (TPI-N) and hydrophilic fraction (HPI). The results showed that HPO-A was the main DOM fraction in river sediments, constituting 41.2%~69.5% and 38.9%~63.9% of the dissolved organic carbon (DOC) before and after the icebound season, respectively. The DOC values of DOM, HPO-A and HPI in river sediments before the icebound season were higher than those after. The results of three-dimensional fluorescence spectra indicated that humic acid-, fulvic acid-, aromatic protein- and soluble microbial byproduct-like fluorescent materials were present in DOM fractions in river sediments before and after the icebound season. Moreover, the content of aromatic protein-like fluorescent materials in each DOM fraction was the highest. The contents of fluorescent materials in HPO-A and HPI after the icebound season were lower than those before. The results of synchronous fluorescence spectra suggested that the fluorescent materials with E_xcitation wavelength of 285~295 nm and 330~350 nm in DOM fractions in river sediments were released into waters during the icebound season, resulting in significantly decreases in the relative content in DOM fractions in sediments.