The carbon isotopic composition of organic matter from lake sediments has been extensively used to infer variations in productivity. In this paper, based on the study of the contents and δ13C values of organic matter...The carbon isotopic composition of organic matter from lake sediments has been extensively used to infer variations in productivity. In this paper, based on the study of the contents and δ13C values of organic matter in different types of lakes, it has been found that δ13C values of organic matter have different responses to lake productivity in different lakes. As to the lakes dominated by aqutic macrophytes such as Lake Caohai, organic matter becomes enriched in 13C with increasing productivity. As to the lakes dominated by aquatic algae such as Lake Chenghai, δ13C values of organic matter decrease with increasing productivity, and the degradation of aquatic algae is the main factor leading to the decrease of δ13C values of organic matter with increasing productivity. Therefore, we should be cautious to use the carbon isotopic composition of organic matter to deduce lake productivity.展开更多
Based on total carbon(C) and C isotopes in sediment cores,sedimentary organic carbon(SOC) was quantified in three types of mangrove sites(barren flat sites without mangroves,mangrove plantations,and natural mangrove f...Based on total carbon(C) and C isotopes in sediment cores,sedimentary organic carbon(SOC) was quantified in three types of mangrove sites(barren flat sites without mangroves,mangrove plantations,and natural mangrove forests),which were considered to represent a continuum from least restored to most restored sites in southern China.SOC densities in the barren sites,plantations,and natural forests were 90,170 and 288 Mg ha 1,respectively.We inferred that mangrove restoration increased SOC accumulation in coastal areas.At 0-70 cm depth,SOC δ 13 C values in both mangrove sites ranged from 27.37‰ to 23.07‰ and exhibited gradual enrichment with depth.In contrast,the values in the barren flat sites remained around 22.19‰ and fluctuated slightly with depth.At 0-60 cm,the 14 C ages of the SOC in the barren flat site,the natural mangrove site,and the artificial mangrove site ranged from 1 397 to 2 608,255 to 2 453,and 391 to 2 512 years BP,respectively.In both types of mangrove sites but not in the barren flat sites,the enrichment of δ 13 C with depth was related to increases in SOC decay and SOC age with depth.According to analysis of 14 C age,much of the mangrove-derived C was transported and stored at 0-60 cm depth under anaerobic conditions in both mangrove sites.The sediments of mangrove forests in southern China sequester large quantities of SOC during mangrove restoration.展开更多
基金supported by the National Basic Research Program of China (Grant No. 2006CB403201)the National Natural Science Foundation of China (Grant No. 40673068)
文摘The carbon isotopic composition of organic matter from lake sediments has been extensively used to infer variations in productivity. In this paper, based on the study of the contents and δ13C values of organic matter in different types of lakes, it has been found that δ13C values of organic matter have different responses to lake productivity in different lakes. As to the lakes dominated by aqutic macrophytes such as Lake Caohai, organic matter becomes enriched in 13C with increasing productivity. As to the lakes dominated by aquatic algae such as Lake Chenghai, δ13C values of organic matter decrease with increasing productivity, and the degradation of aquatic algae is the main factor leading to the decrease of δ13C values of organic matter with increasing productivity. Therefore, we should be cautious to use the carbon isotopic composition of organic matter to deduce lake productivity.
基金Supported by the National Basic Research Program (973 Program) of China (No. 2009CB421101)the Knowledge Innovation Program of the Chinese Academy of Sciences (No. KSCX2-SW-132)the Guangdong Sci-Tech Planning Project(Nos. 2008A030203007 and 2010B060200039)
文摘Based on total carbon(C) and C isotopes in sediment cores,sedimentary organic carbon(SOC) was quantified in three types of mangrove sites(barren flat sites without mangroves,mangrove plantations,and natural mangrove forests),which were considered to represent a continuum from least restored to most restored sites in southern China.SOC densities in the barren sites,plantations,and natural forests were 90,170 and 288 Mg ha 1,respectively.We inferred that mangrove restoration increased SOC accumulation in coastal areas.At 0-70 cm depth,SOC δ 13 C values in both mangrove sites ranged from 27.37‰ to 23.07‰ and exhibited gradual enrichment with depth.In contrast,the values in the barren flat sites remained around 22.19‰ and fluctuated slightly with depth.At 0-60 cm,the 14 C ages of the SOC in the barren flat site,the natural mangrove site,and the artificial mangrove site ranged from 1 397 to 2 608,255 to 2 453,and 391 to 2 512 years BP,respectively.In both types of mangrove sites but not in the barren flat sites,the enrichment of δ 13 C with depth was related to increases in SOC decay and SOC age with depth.According to analysis of 14 C age,much of the mangrove-derived C was transported and stored at 0-60 cm depth under anaerobic conditions in both mangrove sites.The sediments of mangrove forests in southern China sequester large quantities of SOC during mangrove restoration.
