沉积学报2012，Vol.30Issue(1)：128-136,9.
长江口盐沼土壤有机质分布与矿化的空间差异
Spatial Differentiation of Soil Organic Matter Distribution and Mineralization in the Salt Marsh of the Yangtze Estuary
摘要
Abstract
Two transects（Transect I,Transect II） were selected in areas with Spartina alterniflora,and native vegetation,respectively,for investigation of both distribution and mineralization of soil organic matter（SOM） in the Chongmingdongtan salt marsh of the Yangtze Estuary,China.This study is based the on content of particulate organic carbon（POC）,δ13C value of POC,molar ratio of C/N,and grain size characteristics of drilling cores in high tidal flat（core DT-01-2,core DT-08-1）,middle tidal flat（core DT-02-1,core DT-08-2） and bare flat（core DT-03-2,core DT-08-3）.Cores with the same altitude at the two transects contrast in variations of both POC content and δ13C value with depth,and are different in average values of δ13C and POC content,respectively.The average content of POC of core DT-01-2（0.8%） is markedly greater than that of POC of core DT-08-1（0.47%）.The average content of POC of core DT-02-1（0.38%） is greater than that of POC of core DT-08-2（0.11%）.δ13C values of core DT-08-1 average-24.52‰,and the average value of δ13C of core DT-01-2 is-19.73‰.The average value of δ13C of core DT-08-2（-22.06‰） is close to that of δ13C of core DT-02-1（-22.92‰）.Therefore,the variation trend of SOM composition from high tidal flat（core DT-01-2） to middle tidal flat（core DT-02-1） of Transect I is not consistent with that of SOM composition from high tidal flat to middle tidal flat of Transect II.This may be due to differences in SOM composition between the two transects. Transect I was located in the area with invasive Spartina alterniflora that is of C4 type plant.POC content is positively correlated with δ13C value for core DT-01-2,suggesting that organic components from Spartina alterniflora are predominant in SOM at the drilling site.Core DT-01-2 contrasts markedly with core DT-08-1 in correlation between δ13C value and POC content.This is due to the difference in vegetation type between the sites of the two cores,with C3 type plant at the site of core DT-08-1 and C4 type plant at the site of core DT-01-2.The average content of POC of core DT-01-2 is the greatest among those of POC of the studied cores,which may correlate to the high primary production of Spartina alterniflora.Core DT-02-1 is different with core DT-01-2 in correlation between δ13C value and POC content,and is similar to core DT-08-1 that is located in the area with native vegetation.This suggests that SOM at the site of core DT-02-1 are mainly composed of organic components from primary sediments that are transported by the Yangtze River.The correlation between δ13C value and POC content of core DT-02-1 has not been changed thoroughly by the organic components from Spartina alterniflora,which may correlate to the weaker mineralization of SOM,due to the limited time period for the development of middle tidal flat.Spartina alterniflora has produced marked impacts on both content and composition of SOM in the high tidal flat,and discernable impacts on composition of SOM in the middle tidal flat.Native vegetation has exerted marked influence on composition of SOM in the high tidal flat.Salt marsh vegetations have therefore made remarkable impacts on distribution and mineralization of SOM.Organic components of different stages of mineralization are mixed in the SOM of the high tidal flat.SOM composition is relatively simple in the middle tidal flat,indicating that SOM mineralization is less complicated there.Both clay content and water content vary markedly with depth,suggesting that sedimentary sequences have initial constraints on distribution of materials with depth in the salt marsh.Cores with different altitudes contrast markedly in both vertical distribution and mineralization of SOM.Soil carbon dynamics are constrained by the characteristic sedimentary processes on the salt marsh of the Yangtze Estuary.关键词
盐沼/碳稳定同位素/碳矿化/长江口Key words
salt marsh/stable carbon isotope/carbon mineralization/the Yangtze Estuary分类
海洋科学引用本文复制引用
陈庆强,杨艳,周菊珍,张国森,崔莹..长江口盐沼土壤有机质分布与矿化的空间差异[J].沉积学报,2012,30(1):128-136,9.基金项目
国家自然科学基金项目（批准号：40772210,40202032）资助 （）
