城镇与城郊污染河道中DOM成分分布与影响因素

河道水环境的溶解性有机物（dissolved organic matter,DOM）是全球碳循环的重要环节.在国内当前城镇河道污染治理攻坚的紧迫形势下,探究河道DOM受不同类型的外源污染、内源次生污染及天气模式等因素的影响,是明晰关键污染成因的前提.为了解析受生活污水污染的城镇河道与受水产养殖业、种植业及畜禽养殖业污染的城郊河道中DOM成分与当量的差异,以某大型城市作为研究区域,以城镇河道、城郊河道与水源地共21个点位的表层水与沉积物为研究对象,应用了三维荧光光谱-平行因子分析（excitation-emission matrix-parallel factor analysis,EEM-PARAFAC）.结果表明：①城镇与城郊河道水体DOM成分都以蛋白质类成分为主（酪氨酸类与色氨酸类成分）,含有少量腐殖酸类成分,但城镇河道水体存在人为腐殖酸类成分;②城镇河道与市郊河道DOM成分的形成原因截然不同,城镇河道主要受生活污水污染与内源次生污染,导致人为腐殖酸类成分增多.城郊河道主要受富含N、P的农业废水污染,促进自养细菌的内源代谢使蛋白质类成分增多,这可能是形成其现有DOM特征的关键原因;③降雨产生的雨水径流与城市溢流将外源污染物输送到河道中,同时水力搅动等水动力学因素通过稀释等物理作用影响了表层水与沉积物中的DOM成分分布.     

Resolving the variability of CDOM fluorescence to differentiate the sources and fate of DOM in Lake Taihu and its tributaries

Taihu Basin is the most developed area in China, which economic development has resulted in pollutants being produced and discharged into rivers and the lake. Lake Taihu is located in the center of the basin, which is characterized by a complex network of rivers and channels. To assess the sources and fate of dissolved organic matter (DOM) in surface waters, we determined the components and abundance of chromophoric dissolved organic matter (CDOM) within Lake Taihu and 66 of its tributaries, and 22 sites along transects from two main rivers. In Lake Taihu, there was a relative less spatial variation in CDOM absorption a_CDOM(355) with a mean of 2.46 ± 0.69 m⁻¹compared to the mean of 3.36 ± 1.77 m⁻¹ in the rivers. Two autochthonous tryptophan-like components (C1 and C5), two humic-like components (C2 and C3), and one autochthonous tyrosine-like component (C4) were identified using the parallel factor analysis (PARAFAC) model. The C2 and C3 had a direct relationship with a_CDOM(355), dissolved organic carbon (DOC), and chemical oxygen demand (COD). The separation of lake samples from river samples, on both axes of the Principal Component Analysis (PCA), showed the difference in DOM fluorophores between these various environments. Components C1 and C5 concurrently showed positive factor 1 loadings, while C4 was close to the negative factor 1 axis. Components C2 and C3 showed positive second factor loadings. The major contribution of autochthonous tryptophan-like components to lake samples is due to the autochthonous production of CDOM in the lake ecosystems. The results also showed that the differences in geology and associated land use control CDOM dynamics, such as the high levels of CDOM with terrestrial characteristics in the northwestern upstream rivers and low levels of CDOM with increased microbial characteristics in the southwestern upstream rivers. Most of river samples from the downstream regions in the eastern and southeastern plains had a similar relative abundance of humic-like fluorescence, with less of the tryptophan-like and more of the tyrosine-like contributions than did samples from upstream regions.     

基于有色溶解性有机质(CDOM)解析陆源污染物在东海区域的分布特征

随着"陆海统筹"海洋保护战略的提出,近海水质修复越来越依靠对污染源数据的准确掌握,而活性磷酸盐和总无机氮等常规水质指标不能对海洋中陆源污染物进行有效指示.因此,本研究利用三维荧光光谱结合平行因子分析（EEM-PARAFAC）等技术分析了象山港和东海不同深度有色溶解性有机质（CDOM）的组成和分布特征,探讨基于CDOM快速分析技术的近海水质评价方法.结果表明,象山港水质受沿岸排放影响显著,其氮磷营养盐、陆源腐殖质（EEM-PARAFAC组分C1和C4）和生活源类蛋白质（C3和C5）物质显著高于东海表层水体.在东海水体中,5个荧光组分的高值区主要分布在北部近岸表层海域,与盐度分布相反,清晰表明长江冲淡水等陆源输入对CDOM的显著影响.相关性分析表明,陆源物质输入是东海表层水体中污染物的重要来源,而底层污染物的来源则更为复杂.总体上,污水类物质较大程度地改变了东海北部表层CDOM的组成.本研究表明,利用EEM-PARAFAC等技术可快速有效地识别海洋中CDOM的来源,深刻揭示了陆源排放对海洋水质的影响程度,可为"陆海统筹"海洋保护策略提供技术支撑.     

典型岩溶水系统中溶解性有机质的运移特征

西南岩溶水系统中有机质和养分有独特的产生、分解和保存方式,了解有机质与养分循环耦合机制是恢复和优化调控这些脆弱生态系统退化的科学基础.以桂林寨底地下河系统为研究对象,对岩溶地下水的补给、径流、排泄过程中DOM的性质和行为变化进行示踪分析,为深刻认识岩溶地下水DOM的生物地球化学循环提供科学依据.结果表明共检验出3种DOM荧光组分,其中C1、C2为陆源输入的类腐殖质荧光有机物,C3则为内源类蛋白酪氨酸荧光有机物.DOM荧光组分以陆源类腐殖质荧光组分为主,反映了夏季丰水期外源输入对地下水系统DOM的重要贡献.与传统理化指标相比,岩溶地下水系统的DOM空间变化更加明显,也更能反映出地下水系统的细微变化.传统的理化指标主要反映地下河系统的区域特征,而DOM荧光组分则更多地反映了采样点的类型差异.     

岷江上游水体中DOM光谱特征的季节变化

川西北高原湿地和高山峡谷区是岷江等河流重要集水区,地表水体中溶解性有机质(DOM)更多受环境背景影响,DOM来源与结构特征对认识流域有机碳输出通量及模式有重要意义.本文对岷江上游在4月(枯水期末)和10月(丰水期末)分别进行沿程地表水采样并测定了DOM三维荧光光谱(EEM),结合平行因子模型(PARAFAC)分析岷江上游水体DOM沿程和季节变化特征.结果表明,DOM荧光峰(类腐殖峰A、C和类蛋白峰B、T)沿程波动趋势和程度不同;枯水期末(4月)A、C峰强而丰水期末(10月)B、T峰强.PARAFAC识别出3个荧光组分,即C1(250~260/380~480 nm,类腐殖质,占比48.68%~65.02%),C2(300~330/380~480 nm,类腐殖质,占比23.17%~29.83%)和C3(270~280/300~350 nm,类蛋白质,占比11.83%~21.53%);枯水期末(4月)组分沿程波动更明显,其中C1沿程波动最显著.荧光指数(FI)均值在1.4~1.9之间,说明不同季节DOM均有内外源混合特征;枯水期末(4月)DOM腐殖化、芳香性和疏水性高,表明DOM陆源贡献更大,而丰水期末(10月)DOM自生源贡献比枯水期更高.CDOM浓度[a(355)]与类腐殖质浓度[Fn(355)]极显著正相关,这也证实岷江上游水体中DOM的陆源输入.C1、C2在枯水期末(4月)相关性极显著而丰水期末(10月)相关性未达到显著性水平,进一步表明岷江上游水体中DOM的外源性及季节性差异.     

同温混合初期主库区沉积物间隙水DOM的光谱特征——以周村水库为例

运用紫外-可见光谱技术以及结合平行因子分析法的三维荧光光谱（EEM-PARAFAC）技术,对周村水库秋末同温混合初期的沉积物间隙水中溶解性有机物（DOM）的光谱特征进行分析.结果表明：周村水库沉积物间隙水DOM的紫外-可见吸收光谱并无明显特征峰,吸收系数的变异系数在50%~330%之间,表明其性质在不同深度上存在差异;E2/E3、E3/E4随深度增加,说明富里酸所占DOM的比例随沉积物深度增加而升高;三维荧光光谱中分离了4个组分,分别为类富里酸（C1、C2）、类蛋白（C3）和类腐殖酸（C4）;类蛋白（C3）与类腐殖酸（C4）具有显著的相关性（P<0.01,R=0.905）;DOM总荧光强度以及各组分荧光强度随着沉积物深度的增加均呈下降趋势,但DOM中腐殖质所占比例随深度逐渐增加,各样点间各荧光组分的荧光强度与组分比例差异显著;水库沉积物间隙水的高FI（1.8~2.0）和BIX（>1.0）,以及低HIX（<4.0）的荧光特征指数,说明不同深度DOM的腐殖化程度低,均来源于微生物作用.