近百年来异龙湖有机碳和无机碳埋藏响应水体富营养化的协同变化特征  

Synergistic changes of organic and inorganic carbon burial in response to eutrophication in Yilong Lake over the past 100 years

作　　者：李平[1,2] 陈光杰 孔令阳[1] 黄林培 王旭[1] 杨关绍 索旗 李静 王露[1] 韩桥花 周起 郭雯 李蕊 张涛[1] LI Ping;CHEN Guang-jie;KONG Ling-yang;HUANG Lin-pei;WANG Xu;YANG Guan-shao;SUO Qi;LI Jing;WANG Lu;HAN Qiao-hua;ZHOU Qi;GUO Wen;LI Rui;ZHANG Tao(Yunnan Key Laboratory of Plateau Geographical Processes and Environmental Changes,Faculty of Geography,Yunnan Normal University,Kunming 650500,China;School of Resource and Environment,Xichang University,Xichang 615013,China)

机构地区：[1]云南师范大学地理学部,高原地理过程与环境变化云南省重点实验室,云南昆明650500 [2]西昌学院资源与环境学院,四川西昌615013

出　　处：《中国环境科学》2023年第10期5489-5502,共14页China Environmental Science

基　　金：国家自然科学基金资助项目(42171072);云南省重点研发计划项目(202203AC100002-02);异龙湖高原浅水湖泊云南省野外科学观测研究站资助项目(202305AM070002);云南省John P.Smol院士工作站资助项目(202005AF150005)。

摘　　要：湖泊碳埋藏模式及其动态变化对陆地碳汇通量与全球碳收支估算具有重要影响,然而现有湖泊碳埋藏评估主要基于有机碳的埋藏模式,缺乏对无机碳埋藏以及有机碳-无机碳协同变化过程的系统评估.本文通过对云南岩溶区异龙湖开展沉积物岩芯样品的多指标分析和湖盆3个点位的记录对比,结合210Pb、137Cs年代学序列,识别了1900年以来异龙湖有机碳和无机碳埋藏通量的变化历史和空间特征,并甄别了二者协同变化的主要特征及其转化路径.结果表明,近百年来流域开发导致的营养盐长期输入(如沉积物氮和磷的持续富集)显著提高了异龙湖的内源初级生产力,表现为1900~2020年间沉积物藻类色素含量持续增加,蓝藻叶黄素浓度由~7.02μg/g显著增加到~38.99μg/g.同期有机碳和无机碳的埋藏通量均出现持续的上升趋势,且两者的同步变化特征显著(r=0.98~0.99,P<0.001).回归分析表明,藻类生物量是碳埋藏通量上升的主要驱动因子(R^(2)=0.33~0.91,P<0.001),指示了藻类光合作用以及“生物碳泵”效应对碳埋藏过程的驱动作用.在流域地表物质输入强度总体下降(如磁化率信号和沉积物C:N比值的减小)的背景下,藻类生物量和内源有机碳的持续上升导致了有机质矿化过程中自生碳酸盐的转化作用明显增加(如无机碳δ13C信号的持续下降),进而促进了有机碳与无机碳埋藏通量的协同增长.上述结果表明,水体富营养化过程促进形成了有机碳和无机碳埋藏通量同步增加的长期模式,加强了异龙湖有机碳和无机碳埋藏过程的耦合作用.因此在人类活动与气候变化持续的背景下,对岩溶地区湖泊碳埋藏模式的科学评估需要关注无机碳埋藏过程及其对陆地碳汇通量的动态影响.Carbon burial and its dynamic change in lakes play an indispensable role in the global carbon budget and residual land sink.Carbon sequestration in hard water lakes and other inland waters is deemed to be an important sink process owing to carbonate weathering coupled with aquatic photosynthesis,which stimulates continuous organic carbon and inorganic carbon burial.However,existing assessment paradigms are mainly based on organic carbon,lacking a comprehensive understanding of inorganic carbon burial and its synergistic change with organic carbon.Here,the history of carbon burial fluxes over the past century through multi-proxy and spatial sediment surveys of Yilong Lake in the karst area of Yunnan province was analyzed,in combination with 210Pb and 137Cs chronological profiles,for uncovering the patterns and mechanisms of synergistic changes in organic and inorganic carbon burial.The results showed that the allochthonous primary productivity in Yilong Lake has been significantly elevated due to nutrient input caused by watershed cultivation(e.g.,enrichment of sediment nitrogen and phosphorus contents),with sediment pigment content increasing from 7.02μg/g in~1900 to 38.99μg/g in~2020.The accumulation rates of both organic and inorganic carbon showed a continuous trend of increasing and a high degree of synergistic changes(r=0.99,P<0.001).Regression analysis further showed that algal biomass was the main factor in driving the accumulation rates of both organic and inorganic carbon(R^(2)=0.33~0.91,P<0.001).This indicated that algal photosynthesis and the"biological carbon pump"effect have largely controlled the processes of carbon burial.With the general decline of allochthonous watershed export(as evidenced by a decline of sediment magnetic susceptibility signal and C:N ratio)and a continuous increase of algal biomass,more allochthonous organic carbon can be transformed to authigenic carbonates(as evidenced in a sustained depletion ofδ13CTIC)during the decaying and mineralization of organic matters,enhancing t

关 键 词：富营养化 碳埋藏 无机碳 协同变化 异龙湖 

分 类 号：X524[环境科学与工程—环境工程]