Carbon Storage In The Seagrass Sediments Of Guangxi,China

As carbon dioxide and other greenhouse gases?CH₄,N₂O etc.?are increasing which lead to climate change.The“Blue Carbon”emphasizes an important role of seagrass in organic carbon burial and storage.The carbon sequestered by the global seagrass ecosystem is one of the most important components of blue carbon.The total amount of carbon captured and sequestered annually in sediments is second only to coastal salt marsh in various coastal ecosystems.However,compared with other ecosystems,the global blue carbon data on the sediment carbon pools in Chinese sea grass ecosystem,especially deep sediments?>50 cm?,are rarely reported.Therefore,this research compares different species in Guangxi which based on the organic carbon content in deep sediments of sea grass beds,the analysis of the organic carbon space in the ecosystem carbon pools in the intertidal zones of Guangxi,the vegetation habitats?mangroves and seagrass?and the non-vegetation habitats?barren tidal flat?sediment organic carbon distribution pattern,the effects of sea grass species,soil physicochemical properties and other factors on the spatial distribution of organic carbon in sediments were investigated,and the organic carbon storage of seagrass beds in Guangxi was estimated.This is the first quantitative study of the deep-seated carbon stocks in Guangxi Sea grass.The results show that:?1?The organic carbon content in sediments from 0-100 cm depth of sea grass beds in Guangxi lies between 0.06%and 2.80%,the average organic carbon content is 0.35%,and the median is 0.23%,which is lower than the organic carbon content of the adjacent mangrove sediments,higher than the average 0.27%of the organic carbon content in the adjacent barren tidal flat sediments.?2?The organic carbon density of sediments from 0-100 cm deepth of sea grass beds in Guangxi lies between 14.48 to 127.17 MgC/ha,with an average of 48.32 MgC/ha,which is lower than the average density of organic carbon in the adjacent mangrove sediments?81.95MgC/ha?.Above average density of organic carbon in adjacent barren tidal flat sediments?30.78MgC/ha?.?3?The sequence of carbon density for different types of seagrass beds sediments was?was???is?estimated to be:Halophila beccarii?83.98 MgC/ha?,Zostera japonica?35.83MgC/ha?,Halophila ovalis?14.48 MgC/ha?.?4?The organic carbon density of 0-100 cm sediments in seagrass beds in Guangxi ranged from 1.00 to 1.82 g/cm³,with an average of 1.48 g/cm³ and a median of 1.50 g/cm³.?5?The organic carbon density?average?and carbon storage of seagrass bed sediments in Guangxi are 48.32 MgC/ha and 26721.26 MgC,respectively,which was is lower than the average carbon density of the global seagrass bed?152.17 MgC/ha?;?6?Under the same habitat conditions,the carbon density of the bay-type sediment samples is higher than that of the open sea and estuarine sediment samples.The influence degree of habitat types on soil organic carbon content and organic carbon density is different,mainly related to different types of soil dry bulk density,topography,and hydrological environment.?7?The physical and chemical properties of soil are important factors affecting the organic carbon content of sediments.The contents of organic carbon in sea grasses,mangroves,and barren tidal flat sediments are significantly negatively correlated with the bulk density,and are significantly positively correlated with the TN content.There are no correlation with the TP content.There is a very significant positive correlation between organic carbon content and TP content in barren tidal flat sediments.The organic carbon content in seagrass sediments is significantly negatively correlated with water content.This research fills the data gap of organic carbon pools in Chinese sea grass beds sediments,provides basic data for the evaluation of the carbon sink function of seagrass beds in south China.