Concentration Characteristics And Influencing Factors Of Organic Amines,Dimethyl Sulfide And Their Precursors In Marine Environment

The classic CLAW hypothesis believes that marine phytoplankton will synthesize DMSP(Dimethylsulphoniopropionate,DMSP)in response to pressures such as salinity,and the dimethyl sulfide(DMS)produced by bacterial degradation will be exchanged between the sea and air.When it enters the ocean atmosphere by other means,DMS will continue to be oxidized to produce Methanesulfonic acid(MSA)and sulfuric acid.MSA,etc.can nucleate to produce new particles or promote the growth of particulate matter,thereby increasing the concentration of cloud condensation nuclei(CCN).By increasing the scale of cloud formation,the intensity of sunlight reaching the ocean is reduced and the greenhouse effect is regulated.The role of.Current studies have also shown that marine animals ingest and accumulate DMSP from phytoplankton and other foods in response to environmental factors such as salinity and depth.After being released and degraded,it also has a greater contribution to the DMS content in the marine environment.However,the CLAW hypothesis has also been questioned by scientists in recent years.Because,in addition to DMSP,trimethylamine oxide(TMAO),glycine betaine(GBT),choline(CHO)and carnitine(Carnitine,CAR)are used as the nitrogen osmotic adjustment of marine organisms.Substances are also widespread in the marine environment.After they are degraded by bacteria,they will produce organic amines such as Trimethylamine(TMA),Dimethylamine(DMA)and Methylamine(MMA),which are chemically more active than DMS.These organic amines are exchanged by the sea and air.Entering the atmosphere can also promote the generation of new particles and the growth of particulate matter in the atmosphere,thereby reducing global warming.Therefore,organic amines are also one of the current international research hotspots.We detected the composition of MSA and organic amines in atmospheric particulate matter samples from the Qinhuangdao Enteromorpha outbreak area,shellfish breeding area,Qingdao Dagu river shrimp and crab breeding area,and Yantai Haiyang fish and shrimp breeding workshop by URG-9000D ion chromatography.The characteristics and effects of DMSP,TMAO and CAR in samples from the Yellow and Bohai Sea,the Northwest Pacific Ocean and the marine animals and algae in the Enteromorpha eruption area of Qinhuangdao by high performance liquid chromatography-mass spectrometry(HPLC-MS/MS)The factors are analyzed,and the contribution value of marine animals and plants to the marine and atmospheric organic amines and MSA is obtained,which is of great significance for further understanding the concentration differences,sources and climate effects of organic amines and MSA in the marine environment.The results of the study are as follows:(1)Analysis of the concentration of organic amines in marine and atmospheric particulatesBy comparing the content of organic amines in the atmospheric particles in the Enteromorpha outbreak area and the marine aquaculture area,it is found that the DMAH⁺content in the marine aquaculture area is absolutely dominant,with an average content of 0.23±0.37 nmol m^-3,which is 8 times that of the Enteromorpha outbreak area.DMAH⁺The contribution rate of 88%.The total organic amine content in the marine aquaculture area is 7 times that of the Enteromorpha outbreak area,with a contribution rate of 88%,indicating that marine animals have an important contribution to organic amines in the marine environment.(2)MSA-concentration analysis of marine and atmospheric particulate matterThe MSA^-average of PM₁₀atmospheric particles in the outbreak area of??Enteromorpha outbreak area is 0.42±0.43 nmol m^-3,while the MSA^-content in animal breeding area is 0.13±0.13 nmol m^-3,and the MSA^-content in enteromorpha outbreak area is about the animal breeding area.2-3 times of DMSP,which is inversely related to the content of organic amines,indicating that marine algae and other plants are the main contributors to DMSP in the marine environment.(3)The particle size distribution characteristics of organic amine salts in marine and atmospheric particlesIn PM₁₀,the concentrations of DMAH⁺and TMAH⁺are 0.23±0.37 nmol m^-3and0.04±0.08 nmol m^-3,respectively.About 90%of these two ions are present in PM_1.0.The concentrations of MMAH⁺and DEAH⁺are 0.07±0.20 nmol m^-3and 0.02±0.05nmol m^-3,respectively.These two organic amine ions are mainly distributed between PM_0.4-1.6.According to the particle size distribution characteristics of organic amines in atmospheric particles,it is inferred that these organic amine salts are mainly generated through the transformation of gas particles.(4)Study on the content of TMAO and DMSP in different kinds of animals and plantsIn order to better study the distribution of TMAO and DMSP in different types of animals and plants,we divided the samples into six categories:macroalgae,bony fishes,cephalopods,molluscs,shellfish and crustaceans.The average concentration of TMAO is in the range of 1.7×10^-3±0.6×10^-3-3.14±2.14 g kg^-1,and the overall trend is cephalopod>bone fish>crustaceans>shellfish?molluscs>large algae.Cephalopods and bony fishes are higher than the other species,which may be due to the greater depth of the environment in which they are located,and more TMAO accumulates in response to factors such as osmotic pressure.The content of TMAO in animals is much higher than that in macroalgae,indicating that TMAO is mainly accumulated in marine animals.In animal and plant samples,the content of DMSP and TMAO also showed an inverse relationship,and the content of DMSP of macroalgae showed an absolute advantage,indicating that DMSP was mainly accumulated by marine plants.Crustaceans,shellfish and molluscs have higher DMSP content because they accumulate DMSP by filtering algae and phytoplankton.(5)Study on the contents of TMAO,DMSP and CAR in animals in different sea areasIn animal samples from four different sea areas,the total concentration range of TMAO is 0.57±0.68-3.04±0.67 g kg^-1,and the total concentration trend is Huangdonghai>Bohai>Northwest Pacific>Qinhuangdao coast.The content of TMAO in the first three marine animals is significantly higher than that in the coastal area of Qinhuangdao.This may be due to the fact that the depths of the Yellow Sea,the Bohai Sea and the Northwest Pacific Ocean are much higher than those in the coastal areas of Qinhuangdao.Marine animals have accumulated a large amount of pressure in response to depth.TMAO.However,the content of TMAO in the Yellow Sea and the Bohai Sea is higher than that in the Northwest Pacific.We speculate that it may be due to the high eutrophication of the offshore waters of China,which makes marine algae synthesize high concentrations of organic amine precursors,which are transmitted through the food chain,thereby making marine animals contain more More TMAO.(6)Degradation of DMSP and organic amine precursors by bacteriaDMSP and organic amines are important sources of nitrogen,sulfur and energy in the marine environment.The bacteria that degrade organic amines in the marine environment mainly include deep-sea strains such as Alteromonas,Halomonas,Marine Bacillus,Rhodobacter and Vibrio.In the two observation sites,Rose bacillus HIMB11 is significantly higher than other strains,reaching 40%,because Rose bacillus HIMB11 can degrade DMSP,GBT and other substances into DMS and organic amines to participate in the nitrogen and sulfur cycle and obtain energy.HIMB11 plays a very important role in the production and release of organic amines and MSA.