青岛近岸绿潮区溶解有机质微生物可利用性

以青岛近岸绿潮区水体中DOM （溶解有机质）为研究对象，通过室内降解实验计算了水体中DOC （溶解有机碳）的降解效率并分析了水中CDOM （有色溶解有机质）的荧光组分及其变化特征.结果显示，绿潮区不同站点和暴发前后水体中的DOC均发生了不同程度降解，降解过程符合一级降解动力学方程，其中约8.93%~45.10%的DOC可被微生物利用，在时空上受浒苔绿潮影响程度大的水体中DOC降解率最高.应用三维荧光光谱和平行因子相结合的技术，分析确定了绿潮水体中的CDOM包含3种类腐殖质组分（C1、C2、C3）和1种类蛋白质组分（C4），且所有样品中类蛋白质组分含量均显著高于单一类腐殖质组分，表明浒苔绿潮释放的CDOM主要成分是类蛋白质.降解实验中，类蛋白质组分的变化与DOC含量降解趋势相同，而类腐殖质组分逐渐增加.同时，CDOM各荧光参数与微生物可利用性DOC百分比含量（BDOC%）相关性分析的结果和支持向量机的权重分析结果均显示：相对于BDOC%，C4组分为正相关，C1组分负相关，表明BDOC与CDOM组分间的关联度极高，可推测类蛋白质与BDOC均易被微生物降解利用，而类腐殖质与RDOC （惰性溶解有机碳）关系更为密切.该研究揭示了浒苔绿潮生消期间水体中DOM含量的变化及其与不同荧光组分的对应关系，可为解释浒苔绿潮造成的次生生态灾害的原因提供理论基础，并且可利用CDOM组分含量和DOC含量快速推测出BDOC的含量，为海洋现场调查提供便利.

Microbial bioavailability of dissolved organic matter in Qingdao coastal green tide area

Dissolved organic matter (DOM) in the green tide region of Qingdao coastal was studied through indoor degradation experiments, the degradation efficiency of Dissolved organic carbon(DOC) in different seawater was calculated, and the fluorescent components and their variation of colored dissolved organic matter(CDOM) in the water were analyzed. The results showed that DOC in different sites and periods influenced by green tide had all been degraded, and the degradation process accorded with the first-order degradation kinetic equation, in which about 8.93%~45.10% of DOC could be utilized by microorganisms, and the degradation rate of the samples greatly affected by the outbreak of Ulva prolifera green tide was the highest. Based on usage of three-dimensional excitation and emission matrix fluorescence spectroscopy and parallel factor analysis, it was determined that CDOM in green tide water contains three humus components (C1, C2, C3) and one protein component (C4), and the content of protein like components in all samples was significantly higher than that of each single humus component, indicating that the main component of CDOM released by Ulva prolifera green tide is protein like component. In the degradation experiment, the change of protein like components was the same as the degradation trend of DOC content, while humus like components gradually increased. Meanwhile, the results of the support vector machine weight analysis and results of correlation analysis between the fluorescence parameters of CDOM and the percentage content of bioavailable dissolved organic carbon (BDOC%) showed that compared with BDOC, C4component was positively correlated and C1component was negatively correlated, indicating that the correlation between BDOC and CDOM components is very high. It can be inferred that protein-like component and BDOC are easy to be degraded and utilized by microorganisms, and humus-like component is more closely related to RDOC(refractory dissolved organic carbon). This study revealed the changes of DOM content in water during the Ulva prolifera green tide period and its corresponding relationship with different fluorescent components, which could provide a theoretical basis for explaining the causes of secondary ecological disasters caused by Ulva prolifera green tide, and could quickly infer the content of BDOC by using CDOM components and DOC, which offers convenience for marine field investigation.