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Distributions Of Organic Carbon In The East China Sea, Yellow Sea, Northeastern Hainan Rivers And Coasts

Posted on:2010-07-15Degree:MasterType:Thesis
Country:ChinaCandidate:L X TianFull Text:PDF
GTID:2120360275494166Subject:Marine Chemistry
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Organic carbon cycle in the ocean represents an important part in the global carbon cycle.It is of great significance to make aware of the distributions,transportations and transformations of dissolved organic carbon and particulate organic carbon in the ocean. In the present thesis,particulate organic carbon(POC) and dissolved organic carbon (DOC) in water were determined using a Shimadzu TOC-VCPH和Vario ELⅢCHONS. The samples were collected from the sampling locations in the East China Sea,Southern Yellow Sea,northeastern Hainan Rivers and coasts.The main purposes of this current study are to elucidate the distributions,the dominant factors of dissolved organic carbon and particulate organic carbon in the study areas.Moreover,a dissolved organic carbon budget for East China Sea Shelf is evaluated by box-model in this work.DOC and POC samples collected in the East China Sea in February 2007,May 2007 and April 2008 were analyzed.The results showed that high values of DOC and POC were found near the shore and the values decreased seaward.The average values showed April 2008>May 2007>February 2007.The distribution of DOC was controlled by the geography and hydrology factors in winter and spring.The distribution of POC near shore mainly came from terrestrial inputs,while in the continental shelf and edge being greatly impacted by biochemical factors,such as Chl a. The DOC/AOU molar ratios were -0.17,-0.19 and -0.22 in the East China Sea Shelf, Zhejiang Coast and near the Yangtze River estuary respectively,meanwhile,a total of 24%,26%and 31%could be assigned to oxidation of dissolved organic carbon.A DOC budget was estimated for the East China Sea Shelf in February 2007 and the result suggested that the shelf to be a net source of East China Sea.Its net export was 63.6kmol/s,which much lower than in November 2006.Therefor,the difference of export between different months in the same season was large.That was maybe because the differences of DOC concentration and the water flux of Taiwan Strait.POC samples collected in the Southern Yellow Sea in April 2007 were analyzed.The lowest values of POC and PN appeared in the middle in the surface and bottom layer, and near the Qingdao Cold Water(122.5°E,36°N) appeared the highest POC and PN contents and decreased around it.The highest values of DOC appeared near the northwest of Shidao coastal in the surface and bottom layer.The DOC/AOU molar ratio was -0.24 in the A3-F4 transect in the Southern Yellow Sea,meanwhile,a total of 33% could be assigned to oxidation of dissolved organic carbon.The contributions of phytoplankton to POC,estimated by a simple model,were 19.3%±20.8%in the surface layer,24%±18%in the 30 meter respectively.Outer Qingdao,the highest POC mainly came from northern Shandong coastal stream which had high organic carbon concentration.DOC and POC samples collected in the Wanquan River,Wenchang River in December 2006,August 2007 and August 2008 were analyzed.It was obvious seasonal variation of organic carbon concentrations in Wenchang River.It was non-conservative between organic carbon and salinity.Aquacultural activities and mangrove system near the Wenchang River could be major sources for higher DOC observed in the river in winter.In summer(2007.8),near the estuary DOC and POC were greatly influenced by tidal action,showing that high tide lower than low tide.In summer(2008.8),before the typhoon arrival,DOC was mainly impacted by tidal action,while,after the typhoon,the influence of typhoon was higher than tidal action.Colloidal organic carbon between 0.45μm and 0.02μm constituted 19%±9%.It was obvious seasonal variation of organic carbon concentrations in Wanquan River too.It was non-conservative between organic carbon and salinity in winter(2006.12). While,It was conservative between organic carbon and salinity in summer(2007.8 and 2008.8),meanwhile,in August 2008,DOC was influenced by typhoon and tidal action. Colloidal organic carbon between 0.45μm and 0.02μm constituted 27%±10%.The ratio of POC/Chl a were 72-312 in the Wanquan River,43-196 in the Wenchang River and 122.5-334 in adjacent coral reef waters respectively.The contribution of phytoplankton to POC,estimated by a simple model,were 34%in the Wanquan River, 45%in the Wenchang River and 38%in adjacent coral reef water respectively.
Keywords/Search Tags:particulate organic carbon (POC), dissolved organic carbon (DOC), Southern Yellow Sea, East China Sea, Wanquan River, Wenchang River
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