Identification Of Informational Organic Matters And Their Environmental Geochemical Characteristics In The Surface Seawater Of Typical Sea Areas

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 32n-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 than70%.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 and1000 ng mL^-11 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?g L^-11 to 56.93?g L^-1,and pose medium to high ecological risk to marine organisms.N-alkanes were composed of C11-C37congeners with a concentration of 1.76-39.09?g 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?g 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-C₃₇congeners,with a concentration of 1.76-39.09?g 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?g 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?g 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.