Knowledge Management System Of Institute of Oceanology, Chinese Academy of Sciences
|Alternative Title||Identification of informational organic matters and their environmental geochemical characteristics in the surface seawater of typical sea areas|
|Place of Conferral||中国科学院海洋研究所|
|Keyword||信息有机物 检测方法 胶州湾 西太平洋 环境地球化学|
对现有邻苯二甲酸酯和正构烷烃的提取检测方法进行优化，建立了一种可同时检测海水中15种邻苯二甲酸酯和32种正构烷烃（C8-C40）的方法，该方法基于二氯甲烷液相萃取和气相色谱-质谱联用（GC-MS）分析，标准曲线相关系数高于0.996，加标回收率高于70%，已成功应用于胶州湾和西太平洋海山区表层海水中两种信息有机物的检测。首次建立了海水中13种植物激素的提取检测方法，该方法以C18和HLB固相萃取小柱联用进行提取，使用液相色谱-质谱联用（LC-MS）进样检测，标准曲线相关系数高于0.994，在加标浓度为100 ng·mL-1和1000 ng·mL-1时的回收率分别为58.6-117.3%和96.2-100.7%，该方法对于研究藻华等生态现象中植物激素的角色和作用有潜在应用价值。
基于高分辨的四极杆飞行时间质谱（Q-TOF-MS/MS）所得一级、二级质谱数据，结合质谱数据库检索，可以在未知目标有机物的情况下，较为准确地定性分析海水中的微痕量有机物。探索不同pH条件对检测效果的影响，发现强酸性pH条件提取出的有机物分子异质性高, 对酸、酮等活性小分子和木质素、蛋白质、糖类等生物分子的提取效果好。强酸性pH条件更有利于提取带有含氧不饱和基团（如：羧基、羰基）和环氧结构的分子，较低pH条件对于极性较大的分子有更好的提取效果，更适合从天然海水中提取活性分子。pH=2时提取物有效峰数目最多，指认出的分子式种类最多，对定性分析海水溶解有机物的分子组成最为有利。定性筛查海月水母在饥饿状态下释放出的潜在活性物质，发现饥饿状态下的海月水母会释放出大量溶解态有机物，释放出的溶解有机氮（DON）占溶解态总氮（DTN）的30%，溶解有机磷（DOP）占溶解态总磷（DTP）的16%，为“水母在环境压力下会释放信息有机物”这一猜想提供了事实支持。Q-TOF质谱分析发现，具有显著统计学差异的特征离子m/z值主要分布在200-800之间，与之对应，解析出以脂类衍生物为主的13种潜在信息有机物，结合文献检索推测水母在极端环境条件下可能会释放出氧脂素类潜在信息有机物。用这种方法定性筛查胶州湾表层海水中的活性有机物，发现包括己二酸、十六环内酯、甘油酯、黄酮等在内的17 种潜在信息有机物。
2. 研究了胶州湾表层海水中邻苯二甲酸酯、正构烷烃和植物激素这三类信息有机物的环境地球化学特征。相对于其他研究海域，胶州湾表层海水中的信息有机物有相对较高的含量。邻苯二甲酸酯以DiBP和DBP为主，浓度范围为6.00-56.93 μg·L-1，对海洋生物具有中到高等生态风险；正构烷烃由连续的分布的C11-C37同系物组成，总量为1.76-39.09 μg·L-1；植物激素仅检出生长素，含量为2.62-17.56 ng·L-1。信息有机物的组成与分布情况受人类活动影响强烈。
3. 首次报道了西太平洋海山区表层海水中邻苯二甲酸酯的环境地球化学特征，并研究了正构烷烃的环境地球化学特征。西太平洋海山区表层海水中的信息有机物浓度相对较低，邻苯二甲酸酯以DBP、DEHP和DiBP为主，浓度范围为12.13-60.69 ng·L-1；正构烷烃由碳数连续分布的C8-C20同系物组成，总量为0.73-0.74 μg·L-1。信息有机物在西太平洋表层海水中的分布相对均匀，正构烷烃来源以海洋自生为主，邻苯二甲酸酯虽然总体浓度很低，但某些种类已达到产生潜在生态风险的水平。
Informational organic matters refer to the trace organic matters in the natural environment, which can promote or inhibit the survival and growth of biological species or biota, and influence the ecosystem and ecological environment by regulating the abundance and community structure of organisms. It is of great significance to understand the structure of the ecological system and elucidate the mechanism of ecological phenomena by combining the detection of informational organic matters’ chemical structures and concentrations with the research of their distribution characteristics and ecological functions. Although some results had been achieved by the current research on informational organic matters in the marine environment, limited to the lack of analytical methods, the research is fragmented instead of systematic. This dissertation mainly focuses on the establishment of methods extracting and detecting informational organic matters in seawater. Based on literature investigation and non-targeted screening of potential informational organic matters in seawater, phthalates, n-alkanes and phytohormones were selected as objective informational organic matters. The following new results and understandings were obtained:
1. Two sets of methods were constructed to extract and detect trace informational organic matters in seawater. The method of non-polar organic compounds, such as phthalates (PAEs), is based on liquid-liquid extraction and gas chromatography-mass spectrometry. The other method is based on solid phase extraction and Q-TOF mass spectrometry and can be used for non-targeted screening and detecting potential informational organic compounds in components-unknown seawater samples.
A method for simultaneously extracting and detecting 15 phthalates and 32 n-alkanes (C8-C40) in seawater was established by optimizing the available extraction and detection methods. This method was based on dichloromethane extraction and gas chromatography-mass spectrometry (GC-MS) analysis. The correlation coefficients of the standard curves are higher than 0.996, and the spiked recoveries are higher than 70%. Now the method has been successfully applied to the extraction and detection of phthalates and n-alkanes in surface seawater of Jiaozhou Bay and seamounts area in the western Pacific Ocean. The extraction and detection method of 13 phytohormones from seawater was established for the first time. Phytohormones were extracted by C18 and HLB solid phase extraction cartridges and analyzed by liquid chromatography-mass spectrometry (LC-MS). The correlation coefficients of the standard curves were higher than 0.994, and the spiked recoveries of 100 ng mL-1 and 1000 ng mL-1 were 58.56-117.3% and 96.16-100.7%, respectively. This method has potential application value for the study of phytohormones’ roles and effects in ecological phenomena such as algal blooms.
Based on the data of the high-resolution quadrupole time-of-flight mass spectrometry (Q-TOF-MS) and various mass spectrum databases, it is practicable to qualitatively analyze trace organic matters in seawater accurately without objective targeted organic matter. Explore the effect of different pH on the extraction and detection of bioactive organic compounds from seawater. Extracts with strong acidic pH condition were found to be with higher molecular heterogeneity, and their extraction effects to bioactive molecules such as acid and ketone, and biomolecules such as lignin, protein and sugar was better than extracts with other pH conditions. Strong acidic pH benefits to the extraction of molecules with oxygen-containing unsaturated groups (such as carboxyl and carbonyl) and epoxy structures. Lower pH conditions have a better extraction effect for polar molecules, therefore more suitable for extracting bioactive molecules from natural seawater. When pH=2, extracts were extracted with most effective peaks and recognizable molecular formula, which is most favorable to the qualitative analysis of the molecular composition of seawater dissolved organic matter. Qualitatively screen the potential active compounds released by hungry Aurelia aurita. Dissolved organic nitrogen (DON) accounted for 30% of the dissolved total nitrogen (DTN), and dissolved Organic phosphorus (DOP) accounted for 16% of the dissolved total phosphorus (DTP), which provides evidence to the assumption "jellyfish release informational organic matters under environmental stress". Q-TOF mass spectrum showed that the m/z of featured ions with significant statistical differences was mainly distributed between 200-800. Thirteen potential informational organic compounds were identified correspondingly, most of which were lipid derivatives. It suggested that jellyfish might release oxylipins and their derivatives as potential informational organic matters under extreme environmental conditions. Qualitatively screen bioactive organic compounds in the surface seawater of Jiaozhou Bay with the method above, 17 potential informational organic matters were found, including adipic acid, 16-epoxy lactone, glycerol ester and flavonoids.
2. The environmental geochemical characteristics of 3 informational organic matters, phthalates, n-alkanes and phytohormones, in the surface seawater of Jiaozhou Bay, were studied. Compared to other sea areas, informational organic matters in the surface seawater of Jiaozhou Bay were with relatively higher concentrations. Phthalates are dominated with DiBP and DBP, with a concentration ranged from 6.00 μg L-1 to 56.93 μg L-1, and pose medium to high ecological risk to marine organisms. N-alkanes were composed of C11-C37 congeners with a concentration of 1.76-39.09 μg L-1. Among phytohormones, only auxin was detected in the surface seawater of Jiaozhou Bay with a concentration of 2.62-17.56 ng L-1. The composition and distribution of informational organic matters are strongly influenced by human activities.
A total of 12 phthalates were detected in the surface seawater of Jiaozhou Bay, with a concentration of 6.00-56.93 μg L-1. They were concentrated in the northeast than the southwest and concentrated near Huangdao coast than Qingdao. DiBP (51.94%) and DBP (21.59%) are the dominated PAEs. They were accessed to the environment directly by waste disposal or sewage during industrial production or daily life. The risk quotient (RQ) of DiBP to fish is 12.49, and the RQ of DEHP to algae is 5.09, far above the level of high ecological risk. The RQ of DBP and DEHP to other marine organisms also exceeds 0.01, indicating moderate ecological risk to marine organisms.
N-alkanes in the surface seawater of Jiaozhou Bay were composed of C11-C37 congeners, with a concentration of 1.76-39.09 μg L-1. N-alkanes were concentrated in the mouth of Jiaozhou Bay. Their distribution corresponds to the input of industrial wastewater, domestic sewage from the northeastern and western rivers, and ship shipping in the port near the mouth of Jiaozhou Bay. In the middle and outside of the bay, with relatively less influence from human activities, n-alkanes are with obvious main carbon peaks of C24. The anterior peak group has a weak advantage of odd carbon, and the posterior peak group has a weak even advantage, indicating that these n-alkanes are mainly generated by marine algae and bacteria. N-alkanes from human activities were mainly weathered petroleum pollutants, which are composed of C21-C33 congeners, with weak even carbon advantage and single-peak shaped of posterior peaks. The removal mechanism of n-alkanes in surface seawater of Jiaozhou Bay is dominated with physical weathering such as evaporation and dilution. The weathering strength is increased from the inside to the outside of the bay.
Only auxin was detected with a concentration of 2.62-17.56 ng L-1. The distribution of auxin in the surface seawater of Jiaozhou Bay was opposite to phthalates, which indicated that the distribution of phytohormones was similar to marine phytoplankton. With further research, phytohormones are expected to be a biomarker indicating the distribution and growth of phytoplankton in the future.
3. The environmental geochemical characteristics of phthalates and n-alkanes in the surface seawater of seamounts area in the western Pacific Ocean were systematically studied. It was found that the concentration of informational organic matters in the surface seawater of the western Pacific Ocean lower than other sea areas. Phthalates are dominated by DBP, DEHP and DiBP, with concentrations ranged from 12.13 ng L-1 to 60.69 ng L-1. N-alkanes were composed of C8-C20 congeners with concentrations of 0.73-0.74 μg L-1. The distribution of informational organic matters in the surface seawater of the western Pacific Ocean is of little difference. N-alkanes were mainly self-generated from marine organisms. Although the concentration of phthalates is very low, they had reached the level of posing a potential ecological risk to marine organisms, indicating that marine plastic pollution could not be ignored anymore.
A total of 14 phthalates were detected in the surface seawater in the seamount area of western Pacific Ocean with concentrations of 12.13-60.69 ng L-1. Their distribution corresponded to the depth of seawater. Seamount-current interaction was the main factor affecting the distribution of PAEs. DBP (20.66%), DEHP (19.75%) and DiBP (18.72%) were PAEs with the highest concentrations. The RQ of DiBP to algae was 0.06, indicating moderate ecological risk. The RQ of DEHP to crustaceans and fish were also close to 0.01, suggesting potential ecological risks to other marine organisms in the seamounts area of western Pacific Ocean. PAEs in the surface seawater of the western Pacific is mainly derived from storage media such as plastic wreckage or atmospheric particles. They were carried to the western Pacific through long-range atmospheric transportation or currents and were released into the marine environment slowly as the carrier weathering.
N-alkanes in the surface seawater of seamount area in the western Pacific Ocean were composed of C8-C20 congeners with concentrations of 0.73-0.74 μg L-1, and distribution with little difference. The distribution of n-alkanes congeners was completely in the anterior peak group before C20, indicating they were generated by marine organisms. N-alkanes in the surface seawater of the western Pacific Ocean were dominated with C9, with an extremely weak even advantage and CPI and OEP close to 1, showing that the n-alkanes here are not freshly generated. Marine bacterial were involved in the process of their production and degradation, but their contribution is not dominant.
|MOST Discipline Catalogue||理学::海洋科学|
|张倩. 海水中信息有机物的鉴别及在典型海域表层水中的环境地球化学特征[D]. 中国科学院海洋研究所. 中国科学院大学,2019.|
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