长江口溶解有机物光漂白和光矿化表观量子产率  

The apparent quantum yields of dissolved organic matter photobleaching and photomineralization in the Changjiang River Estuary

作　　者：孙欣[1] 宋贵生[1] Xie Huixiang 

机构地区：[1]天津科技大学海洋与环境学院,天津300457 [2]加拿大魁北克大学里姆斯基分校海洋科学研究所

出　　处：《海洋学报》2016年第4期120-129,共10页

基　　金：国家自然科学基金--海洋中无色溶解有机物的光敏及生物降解的研究(41376081);国家重大科学研究计划973计划子课题--陆海间碳循环关键生物地球化学过程及机理研究(2013CB956601)

摘　　要：溶解有机物(DOM)经太阳光照射导致其吸光度(光漂白)和溶解有机碳(光矿化)损失,从而影响水体生态系统光学特性及碳循环。本文通过测定冬季长江口及其邻近海域DOM光降解表观量子产率(AQY),初步探讨了DOM光反应活性在河口及陆架海的变化特征。DOM光降解AQY由口内至口外逐渐递减,且有色溶解有机物(CDOM)光漂白速率是溶解有机碳(DOC)光矿化速率的10倍。Φble(CDOM光漂白表观量子产率)和Φmin(DOC光矿化平均量子产率)在最大浑浊带以东海域与盐度和SUVA254分别呈显著的线性负相关与正相关,表明DOM光反应活性在长江口外受物理混合影响为主,且陆源DOM光反应活性比海源高。此外,最大浑浊带下游DOM光降解AQY显著低于上游。DOM光降解速率随波长的变化呈现非高斯分布,且峰值出现在330nm,积分结果表明UVA是DOM光降解的主要贡献者。本研究结果将为完善我国东海碳通量模型提供帮助。Exposure of dissolved organic matter（DOM）to irradiation leads to the losses of absorbance（photobleaching）and carbon（photomineralization）,thereby impacting the optics and carbon cycle in aquatic environments.In this study,the apparent quantum yields（AQY）of DOM photodegradation in the Changjiang River Estuary and its adjacent sea was investigated to evaluate the variation character of DOM photodegradation in the estuarine and coastal waters.AQY of DOM photodegradation gradually decreases seaward and the photobleaching rate of chromophoric DOM（CDOM）is about ten times that of dissolved organic carbon（DOC）photomineralization along the entire estuary.The significant negative linear correlation between theΦ^-ble（solar spectrum-weighted mean apparent quantum yield of CDOM photobleaching,orΦ^-min：solar spectrum-weighted mean apparent quantum yield of DOC photomineralization）and salinity in the region seaward from the turbidity maximum zone,as well as the significant positive linear correlations betweenΦ^-ble（orΦ^-min）and SUVA254 indicated the physical mixing process should be the dominant factor in controlling the photoreactivity of DOM along the Changjiang River Estuary and the photoreactivity of terrestrial DOM was higher than that of marine-derived DOM.AQY of DOM photodegradation in the lower section was much lower than that in the upper section.The action spectra of DOM phodegradation was characterized as a non-Gaussian style,with the peak response located around 330 nm.The wavelength integrated result demonstrated UVA is the main contributor to DOM photodegradation.This study will provide help to improve the carbon flux model in the East China Sea.

关 键 词：溶解有机物 光漂白 光矿化 表观量子产率 长江口 

分 类 号：P734[天文地球—海洋化学]