河口区溶解有机物三维荧光光谱的平行因子分析及其示踪特性

Resolving Excitation Emission Matrix Spectroscopy of Estuarine CDOM with Parallel Factor Analysis and Its Application in Organic Pollution Monitoring

利用激发发射矩阵荧光光谱(EEMs)并结合平行因子分析(PARAFAC),研究了九龙江口有色溶解有机物(CDOM)的荧光组分特征及其河口动力学行为,并探讨其作为河口区有机污染示踪指标的可行性.利用PARAFAC模型识别出九龙江口CDOM由2类4个荧光组分组成,即类腐殖质荧光组分C1(240,310/382nm)、C2(230,250,340/422nm)、C4(260,390/482nm)及类蛋白质荧光组分C3(225,275/342nm).模型结果表明,传统寻峰法指认的短波类腐殖质A峰区域(240～290/380～480nm)实际上并非一个单独的荧光峰,而是若干荧光组分的组合,并且它与传统上指认的长波区海源类腐殖质M峰、陆源类腐殖质C峰之间存在内在联系.包含M峰的C1组分在河口区随盐度增加呈稀释降低趋势,表明M峰并不能被认为是海洋来源的专有特征峰.类腐殖质组分C1和C2在盐度<6的河口最大浑浊带区表现出一定的添加行为,之后在河口混合过程中呈保守行为,而类腐殖质荧光组分C4则在整个河口混合过程中都呈保守行为.类蛋白质荧光组分C3在河口混合过程中呈不保守行为,并且在总荧光组分中所占比例在高盐度区呈上升趋势.EEM-PARAFAC不仅可示踪九龙江不同支流DOM的特征,并且还可很好地示踪九龙江口的有机污染程度.

The distribution and estuarine behavior of fluorescent components of chromophoric dissolved organic matter（CDOM） from Jiulong Estuary were determined by fluorescence excitation emission matrix spectroscopy（EEMs） combined with parallel factor analysis（PARAFAC）.The feasibility of these components as tracers for organic pollution in estuarine environments was also evaluated.Four separate fluorescent components were identified by PARAFAC,including three humic-like components（C1：240,310 /382 nm;C2：230,250,340 /422 nm;C4：260,390 /482 nm） and one protein-like components（C3：225,275 /342 nm）.These results indicated that UV humic-like peak A area designated by traditional＂peak-picking method＂was not a single peak but actually a combination of several fluorescent components,and it also had inherent links to so-called marine humic-like peak M or terrestrial humic-like peak C.Component C2 which include peak M decreased with increase of salinity in Jiulong Estuary,demonstrating that peak M can not be thought as the specific indicator of the ＂marine＂humic-like component.Two humic-like components C1 and C2 showed additional behavior in the turbidity maximum region（salinity 6） and then conservative mixing behavior for the rest estuarine region,while humic-like components C4 showed conservative mixing behavior for the whole estuarine region.However,the protein-like component C3 showed nonconservative mixing behavior,suggesting it had autochthonous estuarine origin.EEMs-PARAFAC can provide fluorescent fingerprint to differentiate the DOM features for three tributaries of Jiulong River.The observed linear relationships between humic-like components and absorption coefficient a（280） with chemical oxygen demand（COD） and biological oxygen demand（BOD5） suggest that the optical properties of CDOM may provide a fast in-situ way to monitor the variation of the degree of organic pollution in estuarine environments.