Environmental change recorded by radionuclides and organic geochemical signatures in a sediment core from Lake Daihai, North China

	Environmental change recorded by radionuclides and organic geochemical signatures in a sediment core from Lake Daihai, North China
	Sun, Weiwei; Ni, Zhenyu; Meng, Xianqiang; Jiang, Qingfeng; Zhang, Enlou
刊名	CATENA
	2021
卷号	206
英文摘要	Grasslands are one of the most important terrestrial ecosystems, acting as carbon sinks and thus mitigating greenhouse gas emissions. However, large uncertainties remain regarding the effects of long-term anthropogenic activities on the carbon cycling in grassland ecosystems, due to a dearth of high-resolution records. Here we present an organic geochemical lacustrine record from Lake Daihai, in the arable-pastoral ecotone of North China, in order to investigate the response of biogeochemical processes to anthropogenic activities. The chronology, based on radionuclides (Pb-210 and Cs-137), shows that the record spanning the last similar to 80 years, with a temporal resolution of 0.3-7.6 years per centimeter. The total organic carbon (TOC) and total nitrogen (TN) molar ratio and the stable carbon isotopic composition of the total organic carbon (delta C-13(TOC)) range from 13.9 to 19.1 and from 27.0 to 23.9%, respectively, suggesting that the sedimentary organic matter is mainly derived from the terrestrial vegetation-soil system. The significant negative correlation between TOC concentrations and their delta C-13(TOC) is consistent with those in soil profiles, suggesting the delta C-13(TOC) enrichment is mainly due to microbial decomposition of the organic carbon in the vegetation-soil system. From the 1980s to the 2000s CE, rapid agricultural expansion and over-grazing in the watershed reduced the organic carbon input from vegetation to soils, and enhanced the soil organic carbon decomposition, hence affecting the restoration of the carbon sink function of the surrounding grasslands. Furthermore, organic carbon burial rates within Lake Daihai sediments increase significantly with anthropogenic activities, from 4.2 to 39.3 g m(-2) yr(-1) with a sediment focusing correction. The geochemical record as a whole clearly shows that anthropogenic activities have dominated biogeochemical processes of carbon in the arable-pastoral ecotone of North China over the last similar to 80 years.
内容类型	期刊论文
源URL	[http://159.226.73.51/handle/332005/20353]
专题	中国科学院南京地理与湖泊研究所
推荐引用方式 GB/T 7714	Sun, Weiwei,Ni, Zhenyu,Meng, Xianqiang,et al. Environmental change recorded by radionuclides and organic geochemical signatures in a sediment core from Lake Daihai, North China[J]. CATENA,2021,206.
APA	Sun, Weiwei,Ni, Zhenyu,Meng, Xianqiang,Jiang, Qingfeng,&Zhang, Enlou.(2021).Environmental change recorded by radionuclides and organic geochemical signatures in a sediment core from Lake Daihai, North China.CATENA,206.
MLA	Sun, Weiwei,et al."Environmental change recorded by radionuclides and organic geochemical signatures in a sediment core from Lake Daihai, North China".CATENA 206(2021).