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引用本文:季宁宁,刘永,王圣瑞.洱海悬浮颗粒物和表层沉积物有机碳氮同位素来源特征及水质指示意义.湖泊科学,2022,34(1):118-133. DOI:10.18307/2022.0111
Ji Ningning,Liu Yong,Wang Shengrui.The sources characteristics of stable isotope organic carbon and nitrogen in suspended particles and surface sediments in Lake Erhai and their water quality implications. J. Lake Sci.2022,34(1):118-133. DOI:10.18307/2022.0111
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洱海悬浮颗粒物和表层沉积物有机碳氮同位素来源特征及水质指示意义
季宁宁,刘永,王圣瑞
1.北京大学环境科学与工程学院, 国家环境保护河流全物质通量重点实验室, 北京 100871;2.粤港水安全保障联合实验室, 北京师范大学珠海校区水科学研究中心, 珠海 519087;3.北京师范大学水科学研究院, 北京 100875;4.云南省高原湖泊流域污染过程与管理重点实验室, 昆明 650034
摘要:
为探究湖泊水体悬浮颗粒物和沉积物有机碳、氮来源及水质指示意义,分析了2013-2014年洱海悬浮颗粒物和表层沉积物有机碳同位素(δ13C)、氮同位素(δ15N)和C/N比值时空变化特征及与水质的关系.结果表明:①洱海悬浮颗粒物δ13C、C/N、δ15N在旱、雨季差异显著(P<0.05),旱季变化范围分别为-31.75‰~-18.21‰(均值-25.34‰±4.14‰)、9.1~16.9(均值13.3±2.7)、4.9‰~7.4‰(均值6.4‰±1.3‰),雨季变化范围分别为-14.7‰~-23.8‰(均值-20.2‰±3.3‰)、4.6~8.9(均值7.1±1.6)、7.4‰~10.8‰(均值9.3‰±1.8‰).悬浮颗粒物有机碳来源在旱季以陆源C3植物为主(46.0%±6.9%),转变为雨季以浮游植物为主(43.3%±6.1%);氮来源在旱季以陆源植物为主(40.7‰±6.5%),转变为雨季以湖内水生植物和浮游植物为主(39.9%±6.6%).表层沉积物δ13C(-24.0‰~-14.6‰(均值为-18.7‰±4.7‰))和C/N(9.1~15.5(均值为12.1±3.3))均无显著季节差异(P>0.05),δ15N在旱、雨季差异显著(P<0.05),变化范围分别为1.9‰~4.9‰(均值为3.6‰±1.5‰)和0.7‰~7.8‰(均值为4.2‰±1.8‰).表层沉积物有机碳来源在旱、雨季均以陆源C4植物为主(48.2%±19.1%),氮来源旱季以陆源植物为主(44.3%±10.1%),转变为雨季以化肥为主(30.3%±6.8%).两者有机碳与氮来源差异揭示水生和浮游植物来源的有机碳与氮易降解,对水质影响较大,而陆源C4植物和土壤来源的有机碳和化肥来源氮易沉积,对水质影响相对较小.②随机森林回归分析表明,悬浮颗粒物有机质(POM)来源差异(δ13C、C/N)、氧化还原电位和水温(WT)是影响水体多营养循环指标的重要因子,重要度为4.0%~6.9%;POM、C/N和WT是影响叶绿素a的重要因子,重要度为9.3%~10.7%,说明POM来源特征结合水环境因子显著影响水质,而表层沉积物有机质来源相对稳定,对水质无显著影响.为防控洱海水质持续下降,除了加强外源控制,雨季还应重点采取控藻措施.
关键词:  悬浮颗粒物  有机质  碳氮稳定同位素  来源  指示意义  洱海
DOI:10.18307/2022.0111
分类号:
基金项目:国家自然科学基金-云南联合基金项目(U1902207)和云南省高原湖泊流域污染过程与管理重点实验室开放基金项目(2020-02-2-W2,2020-124A-W2)联合资助.
The sources characteristics of stable isotope organic carbon and nitrogen in suspended particles and surface sediments in Lake Erhai and their water quality implications
Ji Ningning1,2,3,4, Liu Yong1, Wang Shengrui5,6,7,8
1.College of Environmental Sciences and Engineering, State Environmental Protection Key Laboratory of All Materials Flux in Rivers, Peking University, Beijing 100871, P. R. China;2.Guangdong-Hong Kong Joint Laboratory for Water Security, Center of Water Research, Beijing Normal University at Zhuhai, Zhuhai 519087, P. R. China;3.College of Water Sciences, Beijing Normal University, Beijing 100875, P. R. China;4.Yunnan Key Laboratory of Pollution Process and Management of Plateau Lake-Watershed, Kunming 650034, P. R. China;5.College of Environmental Sciences and Engineering, State Environmental Protection Key Lab. of All Materials Flux in Rivers, Peking University, Beijing 100871, P.R.China;6.Guangdong-Hong Kong Joint Lab. for Water Security, Beijing Normal University at Zhuhai, Zhuhai 519087, P.R.China;7.College of Water Sciences, Beijing Normal University, Beijing 100875, P.R.China;8.Yunnan Key Lab. of Pollution Process and Management of Plateau Lake-Watershed, Kunming 650034, P.R.China
Abstract:
In order to explore the sources of organic carbon and nitrogen in suspended particles (SP) and sediments, and their implication for water quality, the spatiotemporal variation characteristics of stable isotopic carbon (δ13C), nitrogen (δ15N) and C/N in SP and surface sediments of Lake Erhai were determined in 2013-2014, and their effects on water quality were analyzed. The results showed that, ① The δ13C, C/N and δ15N of SP were significantly different between dry and wet seasons (P<0.05), and varied in the range of -31.75‰ to -18.21‰(the mean was -25.34‰±4.14‰), 9.1 to 16.9(13.3±2.7) and 4.9‰ to 7.4‰(6.4‰±1.3‰) in the dry season, and -23.8‰ to -14.7‰(-20.2‰±3.3‰),4.6 to 8.9(7.1±1.6) and 7.4‰ to 10.8‰(9.3‰±1.8‰) in the wet season, respectively. The end-member mixing model showed, the sources of organic carbon in SP transformed from the terrestrial C3 plants dominated (46.0%±6.9%) in the dry season to phytoplankton dominated (43.3%±6.1%) in the wet season; the nitrogen sources in SP transformed from the terrestrial plants dominated (40.7%±6.5%) in the dry season to aquatic plants and phytoplankton dominated (39.9%±6.6%) in the wet season. There were no significant differences in δ13C and C/N in surface sediments between dry and wet seasons (P>0.05), and the δ13C and C/N varied in the range of -24.0‰ to -14.6‰(-18.7‰±4.7‰)) and 9.1 to 15.5(12.1±3.3), respectively. The δ15N of surface sediments was significantly different between dry and wet seasons(P<0.05), and varied in the range of 1.9‰ to 4.9‰(3.6‰±1.5‰) and 0.7‰ to 7.8‰(4.2‰±1.8‰), respectively. The organic carbon in surface sediments in dry and wet seasons mainly originated from the terrestrial C4 plants, which contributed 48.2%±19.1% of the total organic carbon, and the nitrogen sources in surface sediments transformed from the terrestrial plants dominated (44.3%±10.1%) in the dry season to fertilizers dominated (30.3%±6.8%) in the wet season. The different sources of organic carbon and nitrogen between SP and surface sediments revealed that the organic carbon and nitrogen from phytoplankton were easily degraded, leading to the deterioration of water quality; while the organic carbon from terrestrial C4 plants and soil erosion and nitrogen from fertilizer are easy to deposit, which had little effect on water quality. ② Correlation analysis and random forest regression analysis showed that the source difference of particulate organic matter(POM) (δ13C and δ15N), oxidation-reduction potential and water temperature (WT) in SP were key indicators in the multi-nutrient cycling index for lake water with the importance for 4.0% to 6.9%, while POM, C/N and WT in SP were key indicators in chlorophyll-a for lake water with the importance for 9.3% to 10.7%, which indicated that the source characteristics of POM combining with environmental factors had a significant effect on water quality. However, the source characteristics of organic carbon and nitrogen in surface sediments have no significant effect on water quality. For the protection of Lake Erhai, in addition to further strengthening the control of external loads, the phytoplankton biomass should be mainly controlled in the wet season to avoid further deterioration of water quality.
Key words:  Suspended particles  organic matter  stable isotope of carbon and nitrogen  source  implications  Lake Erhai
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