Dimethylsulfide Cycle In The Yellow Sea And The East China Sea-A Model Study And Application

Dimethylsulfide(DMS)is an important biogenic volatile sulfur compound,the oxidation products of DMS in the atmosphere will contribute to the natural acidity of rainfall and affect the Earth's climate change.The Yellow Sea and the East China Sea has a higher primary productivity and a larger air-sea exchange flux of DMS.Therefore,it is urgent to establish the multivariate statistical model of DMS and the ecological model coupled DMS,discussing the spatio-temporal variation of DMS concentration and its control mechanism.The main work and results are as follows:(1)Multivariate statistical model of DMS concentration in the Yellow Sea and the East China Sea and application.Based on the published data during 2005 to 2015,this paper established two multivariate statistical models of surface DMS concentration,involving surface chlorophyll a(Chl-a)concentration and surface temperature(M.1 and M.2,adjust R square were 0.49 and 0.55 respectively).Results showed that there was a range of temperature,the DMS concentration significantly increased under the rising of Chl-a concentration within the range of temperature;the higher the Chl-a concentration was,the narrower the range of temperature could be.Meanwhile,this paper established the Generalized Additive Mixed Model of surface DMS concentration involving surface Chl-a concentration,total dimethylsulfoniopropionate(DMSPt):Chl-a,temperature and salinity(M.3,adjust R square was 0.72).Results showed that DMS concentration increased with the rising of Chl-a concentration or DMSPt:Chl-a,and Chl-a concentration made a greater contribution;as the temperature rose,the DMS concentration in the mass increased,and this increase in temperature was weakened when the temperature was high;furthermore,DMS concentration could increase under the rising of salinity when the DMSPt:Chl-a level was higher,and DMS concentration could rise first and then fall when the DMSPt:Chl-a level was lower.Compared with the last dacade,if surface Chl-a concentration rose with a average of 10%and surface temperature rose with a average of 1?,setting DMSP:Chl-a and salinity unchanged at the beginning of the 22nd century,summer average DMS concentration in the South Yellow Sea and the East China Sea would elevate about 4.63?12.18%and 1.75?10.76%,respectively;the increase of summer surface DMS concentration in the coast of the South Yellow Sea was lower than that in the South Yellow Sea and the increase of summer surface DMS concentration in the coast of the East China Sea was higher than that in the East China Sea.(2)Ecosystem model coupled DMS in the Yellow Sea and the East China Sea and application.We proposed a parameterization scheme of DMS cycle,migration and transformation of DMSP contained phytoplankton active exudation,predation release,autolysis,free DMSP-lyase cleavage,bacterial DMSP-lyase cleavage and bacterial DMSP-demethylation,migration and transformation of DMS contained free DMSP-lyase cleavage,bacterial DMSP-lyase cleavage,photochemical oxidation,bacterial degradation and air-sea exchange,developed a three-dimensional hyrodynamic module coupled biophysical and geochemical process used for eastern China continental shelf,simulated DMS concentration.During April,November and December,nearshore surface Chl-a and DMS concentration were lower than that in the central of the Yellow Sea,in the other months,it was the opposite;there were two peaks of the surface Chl-a and DMS concentration in the Yellow Sea during the year,and two peaks appeared in spring and autumn respectively;during the period from April to October,surface Chl-a concentration in the North Yellow Sea was lower than that in the South Yellow Sea,and surface DMS concentration in the North Yellow Sea was lower than that in the South Yellow Sea from August to October,but surface DMS concentration in the North Yellow Sea was higher than that in the South Yellow Sea from April to July,during the period from January to March and November to December,surface Chl-a and DMS concentration in the North Yellow Sea were higher than those in the South Yellow Sea,moreover,surface Chl-a and DMS concentration in the East China Sea were lower than those in the Yellow Sea.At the 35° transect,nearshore Chl-a concentration grew from February and got the peak in May,DMS concentration grew from March and got the peak in July and August;there was a wide range of high-value areas of Chl-a and DMS concentration in the central of the South Yellow Sea during April to August,moreover,the core depth of the high-value region declined and the concentration decreased during the period.At the PN transect,high values of Chl-a and DMS concentration basically appeared within the depth of 10 m;nearshore Chl-a concentration grew from April to November,DMS concentration grew from April and got the peak in August;offshore Chl-a and DMS concentration grew from March to May.