Linking sedimentary total organic carbon to210Pbexchronology from Changshou Lake in the Three Gorges Reservoir Region, China.
The influences of total organic carbon (TOC) and total nitrogen (TN) on Lead-210 (210Pb) dating have recently been of increasing concern in lacustrine research. Sediment core from Changshou Lake in the Longxi catchment was investigated for influence of TOC on210Pb dating. Lead-210 excess (210Pbex), Cesium-137 (137Cs) activities, TOC, TN, and particle size were measured. We proposed a dating index based on137Cs chronology and particle size distribution of the lake sediment profile and rainfall erosivities calculated from Longxi catchment metrological records. Increasing trends in TOC and TN were specifically caused by commercial cage fish farming after 1989. The statistically significant correlation between210Pbexactivity, TOC (0.61, p = 0.04) and TN (0.51, p = 0.04), respectively explained post-1989210Pb scavenging. The210Pbexactivity was closely related with coupled peaks of TOC and TN from mass depth 5-10 g cm-2. Higher TOC/TN ratio (8.33) indicated submerged macrophytes and native aquatic algal growth as main source of carbon from enhanced primary productivity because of massive fertilizer use and coherent climate warming. The study supported key hypothesis on vital role of fertilizer usage and algal derived TOC in controlling sedimentary210Pbexactivity at Changshou Lake sediment.137Cs profile and erosive events as time markers provided reliable and consistent sedimentation rate of (1.6 cm y-1).210Pbexactivity decayed exponentially after peak at mass depth 5.68 g cm-2. Therefore, violation of210Pb dating primary assumptions made it inappropriate for sediment dating at Changshou Lake. TOC content must be considered while using210Pb as dating tool for lake sediment profiles.
Key Laboratory of Mountain Surface Processes and Ecological Regulation, Institute of Mountain Hazards and Environment, Chinese Academy of Sciences, Chengdu, 610041, China; University of Chinese Academy of Sciences, Beijing, 100049, China; Abdul Wali Khan University, Mardan, Pakistan.
Raheel
R
Anjum
Key Laboratory of Mountain Surface Processes and Ecological Regulation, Institute of Mountain Hazards and Environment, Chinese Academy of Sciences, Chengdu, 610041, China.
Jinzhang
J
Gao
Key Laboratory of Mountain Surface Processes and Ecological Regulation, Institute of Mountain Hazards and Environment, Chinese Academy of Sciences, Chengdu, 610041, China.
Qiang
Q
Tang
Key Laboratory of Mountain Surface Processes and Ecological Regulation, Institute of Mountain Hazards and Environment, Chinese Academy of Sciences, Chengdu, 610041, China. Electronic address: xiubinh@imde.ac.cn.
Xiubin
X
He
Key Laboratory of Mountain Surface Processes and Ecological Regulation, Institute of Mountain Hazards and Environment, Chinese Academy of Sciences, Chengdu, 610041, China.
Xinbao
X
Zhang
Key Laboratory of Mountain Surface Processes and Ecological Regulation, Institute of Mountain Hazards and Environment, Chinese Academy of Sciences, Chengdu, 610041, China.
Yi
Y
Long
Key Laboratory of Mountain Surface Processes and Ecological Regulation, Institute of Mountain Hazards and Environment, Chinese Academy of Sciences, Chengdu, 610041, China.
Zhonglin
Z
Shi
Key Laboratory of Mountain Surface Processes and Ecological Regulation, Institute of Mountain Hazards and Environment, Chinese Academy of Sciences, Chengdu, 610041, China; University of Chinese Academy of Sciences, Beijing, 100049, China.
Mingfeng
M
Wang
D002244:Carbon / Q000032:analysis / Q000737:chemistry*; D002588:Cesium Radioisotopes / Q000032:analysis / Q000737:chemistry; D002681:China; D004784:Environmental Monitoring; D005308:Fertilizers / Q000032:analysis; D019015:Geologic Sediments / Q000737:chemistry*; D060106:Lakes / Q000737:chemistry*; D007856:Lead Radioisotopes / Q000032:analysis / Q000737:chemistry*; D009584:Nitrogen / Q000032:analysis / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000737:chemistry*
D002588:Cesium Radioisotopes; D005308:Fertilizers; D007856:Lead Radioisotopes; D014874:Water Pollutants, Chemical; D002244:Carbon; D009584:Nitrogen
(210)Pb dating; Algal scavenging; Changshou Lake; Lake sediment; Rainfall erosivity; TOC