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1.
本文测定了海南儋州湾南岸柱状沉积物的粒度、总有机质参数(TOC、C/N和δ13C)和类脂生物标志物含量,并通过端元混合模型使用红树植物特征标志物蒲公英萜醇含量、长链正构烷烃含量和δ13C值半定量区分了海南儋州湾南岸沉积有机质来源,尤其是红树林的贡献。另外,通过估算沉积物的有机碳储量来评估儋州湾红树林区域的储碳能力。在沉积有机质中,陆源、水源和红树植物有机质所占平均比例分别为47%,36%和17%。沉积物柱状样中单位厘米深度沉积物的碳储量范围在0.12~2.90 t/ha。本研究表明,儋州湾地区沉积物中来自于红树林的有机质比例较低,且其碳埋藏量可能低于全球平均水平。修复和保护儋州湾红树林,能够有效提升湿地的碳埋藏效率,从而减缓大气CO2上升对环境的负面影响。本文应用生物标志物和碳同位素方法,半定量区分了红树林生态系统各种来源有机碳的贡献,将蒲公英萜醇作为红树林特征生物标志物应用在计算模型中,能够量化红树植物来源有机碳的贡献,加深对红树林系统有机碳埋藏情况的了解。  相似文献   

2.
通过对曼谷湾顶红树林区柱状沉积物D1的总有机碳(Total Organic Carbon, TOC)、总氮(Total Nitrogen, TN)、稳定碳同位素(δ13C)及粒度等指标的分析,在210Pb建立的年代地层框架的基础上,重建了该地区近百年来有机碳的埋藏记录,并对其影响因素进行了探讨。结果表明,TOC含量和δ13C值变化范围分别为1.35%~2.26%,-24.18‰~-22.67‰,均自下而上表现为先增加后减少的趋势。研究区为河口型红树林,相比海洋型红树林,其沉积物中有机碳来源受红树林影响较小,这是由于受周期性涨落潮和河口径流的冲刷,较轻的红树林碳屑极易被分解或被带至外海,难以在沉积物中存储。综合研究区的环境因素,选择陆源、海源和人为源作为三端元,计算得出柱状沉积物中有机碳以人为源和海源为主,陆源贡献相对较低。1939年以来,人为源有机碳贡献不断增大;1980—2008年间,因入海河流上游修建大坝,导致入海物质通量减少,加之该时期区域气候模式发生变化,降雨量相对减少,陆源有机碳贡献相对降低。因围海造田、围海养殖等人类活动增强,人为...  相似文献   

3.
红树林生态系统位于海洋与陆地的交界处,具有重要的生态服务功能。红树林湿地是重要的碳库,对全球碳平衡有重要影响。然而,由于受到人口增长、社会经济发展和城市化进程加快等人类活动和全球气候变化的影响,红树林正在加速消失。文章以广东湛江市国家级红树林自然保护区为研究区,通过分析红树林沉积物中的有机碳含量及分布特征,讨论人类活动(如,人工养殖)在湿地碳循环中的影响。本研究在研究区内获取15个样品,利用重铬酸钾氧化—还原容量法测定了沉积物中有机碳含量。结果表明:研究区内沉积物有机碳(TOC)含量介于0.68%~2.50%,同时TOC含量与研究区内人工养殖场排污口的距离有密切关系:离排污口越近,TOC值越低;离排污口越远,TOC值越高。此外,研究区内红树林TOC含量与其他红树林湿地TOC含量相比明显偏低,可能与养殖排污抑制红树林的生长和繁殖,从而使其TOC含量明显减少有关。  相似文献   

4.
潮滩作为重要的湿地类型和高效的有机碳汇备受关注,近期围垦、养殖等人类活动和互花米草入侵对潮滩生化环境和有机碳埋藏产生了重要影响。本研究选取了福建三沙湾三处不同植被类型的潮滩各取得沉积物短柱样,测定沉积物的总有机碳含量(TOC)、稳定碳同位素(δ13C),结合210Pbex测试计算的沉积速率,估算了不同区域的有机碳埋藏通量(BC)。结果表明,互花米草阶段和红树林阶段TOC含量分别为0.67%和0.95%,比对应的光滩阶段分别提高了13.6%和26.7%,表明红树林对潮滩固碳效率的提升比互花米草更加显著。在两者的共同生长区域,随时间推移TOC含量显著下降,表明互花米草入侵挤占红树林生长空间之后,降低了潮滩的固碳效率。短柱样沉积物δ13C值分布范围在-24.70~-21.87‰,主要体现海源有机质同位素特征,但也会受潮滩植被生长类型影响。对各短柱样有机碳埋藏通量进行估算,得到研究区红树林生长阶段BC平均值为149.53 g/m2/yr,远高于互花米草生长阶段的平均值57.37 g/m2/yr。  相似文献   

5.
随着工业化进程的加快,湛江湾的生态环境承载力受到了极大的考验。为了解湛江湾生态环境的变化过程,文中利用湛江湾表层柱状沉积物样品中总有机碳含量(TOC)及其稳定同位素、总氮含量(TN)和C/N值的测定,结合端元混合模型,分析了湛江湾沉积物中有机质的来源,探讨了沉积物有机碳同位素的主要影响因素。结果表明,湛江湾沉积物中有机质主要来源为自生藻类,同时也受一定程度陆源输入的影响。沉积序列的元素地球化学参数表明,沉积物δ13C值呈现短暂的负偏随后长期正偏的趋势。底部的负偏可能与大气CO2浓度增加有关,随后δ13C主体正偏的趋势主要受控于气候转暖、生产力增加以及富营养化程度增加的共同影响,暗示了人类活动对湛江湾的生态环境的影响逐渐加剧。其中,人类活动相关的工业、农业有机污染物排放可能是不断加剧海水富营养化的主要原因。  相似文献   

6.
基于莱州湾32个典型站位的表层沉积物样品,系统分析了稀土元素(REE)组成和分布特征以及重金属污染程度和污染来源;探讨了影响重金属和稀土元素分布的环境因素,并从重金属潜在源区、化学蚀变指数(CIA)和REE特征3个角度分析了莱州湾表层沉积物来源。研究表明,稀土元素总量自莱州湾东南部向北部递增,部分稀土元素(Eu、Gd和Tb)含量主要与细粒级的黏土矿物和有机碳含量相关,受化学风化的影响很小。研究区部分站位受到了Cd和Hg的污染,且主要是人类活动富集的;Cu、Pb、Zn可能源于地壳自然风化产物,其中Cu和Zn还与人类活动密切相关;Cr则受自然风化和人类活动的双重影响而富集;大部分重金属含量的累积还受湾内水动力的影响。沉积物源的判别结果显示,研究区CIA平均值为50.83,接近黄河沉积物的CIA值(50.9~59.7),低于中国黄土;研究区稀土元素配分模式和特征参数也与黄河十分接近,表明黄河是莱州湾表层沉积物的重要来源;广利河与潍河-弥河三角洲仅对南部和西南部海域沉积物有贡献,而黄土和山东省土壤对莱州湾沉积物的贡献量相对更少。  相似文献   

7.
根据2006年5月获得的海底表层沉积物和柱状样品测试资料,分析了钦州湾海底沉积物中有害元素Hg的平面分布和垂向分布特征。结果显示:平面分布上,钦州湾口门附近Hg含量较高,Hg影响较大,湾内的Hg含量则较小,湾外向外海方向Hg含量逐渐降低;垂向分布上,海底表层的Hg含量高,向下则逐渐降低,至海底表层70cm以下,Hg值趋于稳定。根据沉积速率,确认约700年前开始,钦州湾受人类活动的影响逐渐增加,至约130年前,人类活动影响加剧。对比历史事件,认为钦州湾海底沉积物Hg含量变化与人类活动相关。总体上,钦州湾海底沉积物Hg测量值均低于标准值,说明其环境目前尚好。  相似文献   

8.
海湾是海洋和陆地相互作用和人类活动最强烈的区域,沉积物中重金属的含量和分布都受到人类活动的影响。为了探究钦州湾沉积物中重金属的含量水平、污染程度和可能来源,本研究分析了钦州湾表层沉积物中Cu、Pb、Zn、Cd、Cr、Hg和As的含量及空间分布,采用地质累计指数(Igeo)和潜在生态风险指数(PERI)定量分析了重金属的污染程度和生态风险,并利用自组织映射(SOM)和正定矩阵因子分解法(PMF)模型评估了重金属的可能来源。结果表明:钦州湾表层沉积物重金属中Zn的平均含量最高,Hg平均含量最低;除个别站位的Pb含量符合海洋沉积物质量第二类标准外,其他重金属含量均符合海洋沉积物质量第一类标准;Igeo结果表明钦州湾表层沉积物主要的污染元素为Pb、Hg和Cu;PERI结果表明Hg是钦州湾表层沉积物主要的生态风险元素。SOM和PMF模型结果表明钦州湾表层沉积物重金属主要受自然来源、农业活动、工业生产活动的共同影响,各来源的相对贡献率分别为39.65%、29.15%和31.20%。  相似文献   

9.
对海南岛红树林柱样中有机生物标志物等生物地球化学参数进行了初步研究.结果显示红树林中有机碳(OC)与总氮(TN)比值范围为5.35-7.47,碳稳定同位素(δ13C)值范围为-25‰--22.9‰.脂肪酸与正构烷烃浓度分布范围分别为7.8-21.8μg·g-1(干重)和3.2-25μg·g-1(干重).在表层沉积物中,红树林植物、细菌与浮游生物的脂肪酸生物标志物各占总脂肪酸的25.4%、12.9%和7.5%,结合较低的OC/TN比值和较高的δ13C值,表征了当地微生物和外源浮游植物的有机质贡献.各类脂肪酸在柱样中表现出不同的降解特征:多不饱和脂肪酸(PUFAs)优先被降解,而长链脂肪酸(LCFAs)则较为稳定,没有明显的降解.碳优势指数(CPI)和平均碳链长度(ACL)显示,埋藏深度越深,有机物的生物化学改造程度越大.  相似文献   

10.
杨海丽  郑玉龙 《海洋学报》2008,30(4):95-103
2005年8月在海南洋浦湾内湾取得1根柱状样,在铅-210定年的基础上分析沉积物粒度、总有机碳含量及其同位素值(δ13C)、总氮含量及其同位素值(δ15N)、生物硅含量、重金属(镍、镉、铬、铜、锌、铅)含量及有机氯农药(六六六、滴滴涕)含量等参数发现,111cm至表层,沉积物中有机碳、总氮、生物硅含量升高,特别是从45cm至表层,它们的含量明显增加,说明该湾内有富营养化趋势。由有机碳与总氮的原子比和有机碳同位素指示的物源信息可知,该湾内有机质来源为藻类和陆源脉管植物的混合,且以陆源输入为主。陆源有机碳含量与总有机碳含量的相关系数为0.917。自23cm至表层有机碳同位素明显偏轻,氮同位素偏重。从111cm至表层,重金属和有机氯农药含量升高。综合分析各环境指标可知,洋浦湾近百年来环境演变可分为三个时期,即20世纪70年代以前、70年代至90年代、90年代至21世纪初,洋浦湾经历了未污染期、轻度污染期、显著污染期。  相似文献   

11.
Mangrove degradation must reduce carbon sequestration in recent years, thereby aggravating global warming.Thus, short-term impacts of human activity on mangrove ecosystems are cause for concern from local governments and scientists. Mangroves sediments can provide detailed records of mangrove species variation in the last one hundred years, based on detailed 210 Pb data. The study traced the history of mangrove development and its response to environmental change over the last 140 years in two mangrove swamps of Guangxi, Southwest China. Average sedimentation rates were calculated to be 0.48 cm/a and 0.56 cm/a in the Yingluo Bay and the Maowei Sea, respectively. Chemical indicators(δ13Corg and C:N) were utilized to trace the contribution of mangrove-derived organic matter(MOM) using a ternary mixing model. Simultaneous use of mangrove pollen can help to supplement some of these limitations in diagenetic/overlap of isotopic signatures. We found that vertical distribution of MOM was consistent with mangrove pollen, which could provide similar information for tracing mangrove ecosystems. Therefore, mangrove development was reconstructed and divided into three stages: flourishing, degradation and re-flourishing/re-degradation period. The significant degradation, found in the period of 1968–1998 and 1907–2007 in the Yingluo Bay and the Maowei Sea, respectively, corresponding to a rapid increase of reclamation area and seawall length, rather than climate change as recorded in the region.  相似文献   

12.
Located between terrestrial and marine ecosystems, mangrove forests are sensitive to changes in climate. The responses of mangrove ecosystems to climate change in the future can be understood by reconstructing past mangrove dynamics using proxies preserved in the intertidal sediments. Considering the complexity of the proxies commonly used, it is necessary to develop a relatively simple, inexpensive proxy. In this study, available chemical tracers (δ13Corg and C:N) of the four cores (YLW02, YLW03, O18, and Q37) from the intertidal zone of the northern Beibu Gulf (NBG) and a three-end-member (mangrove, sea grass, and suspended particulate matter) model was utilized to determine the contribution of mangrove-derived organic matter (CMOM) in carbonate-free sediments. Compared with the summed concentration of mangrove pollen (SCMP), a significant positive correlation between CMOM and SCMP is displayed. The calculated CMOM for an additional 210Pb-dated sediment core from the Yingluo Bay, NBG (YLW01) clearly indicates a mangrove development going through degradation, flourishing, relative degradation, and relative flourishing, which are separately in correspondence with the lowest, highest, lower, and higher air temperature and rainfall in the time intervals of 1890–1918 AD, 1919–1956 AD, 1957–1990 AD, and 1991–2010 AD. This suggests that CMOM preserved in intertidal sediments has a potential to reconstruct historical mangrove development in high resolution, at the very least, along the coasts of the NBG.  相似文献   

13.
广西钦州湾晚全新世红树林演变及对海平面变化的响应   总被引:2,自引:0,他引:2  
Mangroves, widely distributed along the coasts of tropical China, are influenced by Asia monsoon, relative sea level change and enhanced human activity. To predict the impacts of future climate change on mangrove ecosystems, it can be understood by reconstructing past mangrove dynamics using proxies preserved in coastal sediments. In this study, we quantitatively partitioned buried organic matter(OM) sources, collected from a vulnerable mangrove swamp in the Qinzhou Bay of northwestern South China Sea, using a ternary end-member mixing model of δ~(13)C and C:N values. Mangrove-derived OM(MOM) contribution was used as a tracer for mangrove development since 2.34 cal ka BP. This information, together with paleoclimate records(i.e.,speleothem δ~(18)O values, sea level change, grain size parameters) and human activity, was used to divide mangrove development into three stages during the late Holocene: relative flourish(2.34–1.13 cal ka BP), relative degradation(1.13–0.15 cal ka BP) and further degradation(0.15–0 cal ka BP). Before 1.13 cal ka BP, mangroves flourished with a high MOM contribution((88.9±10.6)%), corresponding to stable and high sea level under a warm and humid climate. After 1.13 cal ka BP, rapid fall in relative sea level coupled with the strengthening of the Asian winter monsoon, resulted in mangrove degradation and MOM reduction((62.4±18.9)%). Compared with air temperature and precipitation, the relative sea level fall was the main controlling factor in mangrove development before entering the Anthropocene(the time of the Industrial Revolution). After ~150 cal a BP, reclamation of mangrove swamps to shrimp ponds is the main factor causing mangrove degradation and MOM reduction.  相似文献   

14.
红树林生态系统在全球气候变化和碳循环过程中发挥着很重要的作用,准确评估红树林湿地的碳收支,对于保护和恢复海洋蓝色碳汇以及全球气候治理工作具有重要的意义。本研究以海南东寨港国家级自然保护区的红树林湿地为研究对 象,采用 《对 2006 IPCC 国家温室气体清单指南的 2013 增补:湿地》 (简称 《湿地指南》) 中的计算方法,利用野外现场调查数据及已有的研究成果作为参数,评估和量化海南东寨港红树林湿地在 2010—2018 年期间的碳收支情况。研究表明:(1) 2010 年红树林面积为 1 627.21 hm2,全部为成熟红树林,碳储量为 5.85*105t C;2018 年红树林面积为 1 665.42 hm2,其中 1 625.84 hm2为成熟红树林,碳储量为 6.71*105t C,39.58 hm2为过渡期红树林,碳储量为 4.36*103t C,总碳储量为6.75*105t C。 (2) 2010—2018 年期间红树林碳储量增加了 9.0*104t C。另外,有 1.37 hm2的红树林湿地退化为水域,释放了81.36 t 的碳储量。因此,2010—2018 年期间东寨港红树林湿地碳收支为+8.99*104t C,整体上表现为净碳汇生态系统。本研究结果可为气候变化背景下海南红树林湿地的保护与恢复、风险评估以及气候治理提供科学参考。  相似文献   

15.
The response of mangrove ecosystems to the Asian monsoon in the future global warming can be understood by reconstructing the development of mangrove forests during the Holocene climatic optimum(HCO), using proxies preserved in coastal sediments. The total organic matter in sediments of a segmented core, with calibrated age ranges between 5.6 and 7.7 cal. ka BP and corresponding to the HCO, from the Qinzhou Bay in Guangxi, China, is quantitatively partitioned into three end-members according to their sources: mangrove-derived, terrigenous,and marine phytoplanktonic, using a three-end-member model depicted by organic carbon isotope(δ13Corg) and the molar ratio of total organic carbon to total nitrogen(C/N). The percentage of mangrove-derived organic matter(MOM) contribution is used as a proxy for mangrove development. Three visible drops in MOM contribution occurred at ca. 7.3, ca. 6.9, and ca. 6.2 cal. ka BP, respectively, are recognized against a relatively stable and higher MOM contribution level, indicating that three distinct mangrove forest degradations occurred in the Qinzhou Bay during the HCO. The three mangrove forest degradations approximately correspond to the time of the strengthened/weakened Asian winter/summer monsoon. This indicates that even during a period favorable for the mangrove development, such as the HCO, climatic extremes, such as cold and dry events driven by the strengthened/weakened Asian winter/summer monsoon, can trigger the degradation of mangrove forests.  相似文献   

16.
Mangrove forests are vulnerably threatened by sea level rise (SLR). Vegetation organic carbon (OC) stocks are important for mangrove ecosystem carbon cycle. It is critical to understand how SLR affects vegetation OC stocks for evaluating mangrove blue carbon budget and global climate change. In this study, biomass accumulation and OC stocks of mangrove vegetation were compared among three 10 year-old Kandelia obovata (a common species in China) mangrove forests under three intertidal elevations through species-specific allometric equations. This study simulated mangrove forests with SLR values of 0 cm, 40 cm and 80 cm, respectively, representing for the current, future ~100 a and future ~200 a SLR of mangrove forests along the Jiulong River Estuary, China. SLR directly decreased mangrove individual density and inhibited the growth of mangrove vegetation. The total vegetation biomasses were (12.86±0.95) kg/m2, (7.97±0.90) kg/m2 and (3.89±0.63) kg/m2 at Sites SLR 0 cm, SLR 40 cm and SLR 80 cm, respectively. The total vegetation OC stock decreased by approximately 3.85 kg/m2 (in terms of C) from Site SLR 0 cm to Site SLR 80 cm. Significantly lower vegetation biomass and OC stock of various components (stem, branch, leaf and root) were found at Site SLR 80 cm. Annual increments of vegetation biomass and OC stock also decreased with SLR increase. Moreover, significant lower sedimentation rate was found at Site SLR 80 cm. These indicated that SLR will decrease mangrove vegetation biomass and OC stock, which may reduce global blue carbon sink by mangroves, exacerbate global warming and give positive feedback to SLR.  相似文献   

17.
Mangroves can not only provide multiple ecosystem service functions, but are also efficient carbon producers,capturers, and sinks. The estimation of the organic carbon accumulation rate(OCAR) in mangrove sediments is fundamental for elucidating the role of mangroves in the global carbon budget. In particular, understanding the past changes in the OCAR in mangrove sediments is vital for predicting the future role of mangroves in the rapidly changing environment. In this study, three dated sediment cores from interior and fringe of mangroves in the Yingluo Bay, China, were used to reconstruct the spatiotemporal variations of the calculated OCAR since 1900 in this area. The increasing OCAR in the mangrove interior was attributed to mangrove flourishment induced by climate change characterized by the rising temperature. However, in the mangrove fringe, the strengthening hydrodynamic conditions under the sea level rise were responsible for the decreasing OCAR, particularly after the1940 s. Furthermore, the duration of inundation by seawater was the primary factors controlling the spatial variability of the OCAR from the mangrove fringe to interior, while the strengthened hydrodynamic conditions after the 1940 s broke this original pattern.  相似文献   

18.
Located in the intertidal zone of the tropical and subtropical coasts, mangrove forests are an important ecosystem in the global carbon cycle and serve as a protector of local seashores. Under the double impacts of climate change,especially sea-level rise, and human activity, mangrove forests around the world have faced degradation, against which the reconstruction of the historical development of mangrove forests using an effective indicator has been regarded as a necessary strategy for designing a predictable model. As the primary product of mangrove forest, it is reasonable that the content of leaf fragments of mangrove(CLFM) buried in sediments in the form of sub-fossils potentially has the same indicative function for the development of mangrove forests as that of widely-used mangrove pollen. In this study, the leaf fragments of mangrove in two sediment cores(YLW02 and YLW03) drilled in the Yingluo Bay in Guangxi, Southwest China were picked out and weighted for calculation of CLFM, which was used as an indicator of mangrove development after examination of parallelism and a statistical correlation of the CLFM with the concentration of mangrove pollen. The results clearly show that the vertical distribution of the CLFM for the core taken from the landward margin of mangrove forests(YLW03) only parallels that of the local mangrove species(Rhizophora. stylosa) with a significantly positive correlation(R=0.56, P=0.05), while the vertical distribution of the CLFM for the core taken from the interface between seaward margin of mangrove forest and the trunk of tidal creeks of the bay(YLW02) parallels the summed concentration of mangrove pollen(SCMP) with a more positive correlation than that of YLW03(R=0.85, P=0.01), indicating that the trunk outlet of tidal creeks must have been the site where mangrove production gathered from the overall forest rather than from local production. The variations in the CLFM of both cores indicate that overall the mangrove forests in the Yingluo Bay have increasingly flourished over the last 130 years except for the interval of 1940–1950 AD in response to an increase in air temperature and decrease in rainfall, which would have resulted in an increase in seawater salinity;while the coupled extreme increases in air temperature and in rainfall in summer, which would have resulted in extreme decreases in seawater salinity, would be responsible for the relative degradation of mangrove forests in the interval of 1940–1950 AD.  相似文献   

19.
红树林是具有重要碳汇功能的生态系统,其保护和修复成为海洋领域应对气候变化的重要手段。适宜的生境条件是红树林生态修复成功与否的关键因素,而红树植物物种和种植措施等也决定了修复后生态系统结构和功能的发展。本研究综述了红树林生态修复固碳功能的特点,分析了生境条件、物种和种植措施等因素对红树林生态系统固碳效果的影响,以期为红树林生态修复提供参考。总体上,红树林生态修复促进了有机碳在植物体和土壤中的累积,而在生态修复初期红树植被的固碳能力高于土壤。水文条件、滩涂高程、底质条件、物种、种植密度和种苗来源等关系到修复后红树植物的生长、颗粒态有机物的沉降、有机物的输出和保留、有机质的分解等过程,进而影响生态系统的固碳能力。因此,开展红树林生态修复时选择适宜生境条件的修复地块,合理选择物种和种植措施,在提高植被恢复效果的同时可提高红树林固碳增汇的生态功能。  相似文献   

20.
红树林海岸的沉积物输运和碳沉降特征   总被引:1,自引:0,他引:1  
Mangroves play an important role in sequestering carbon and trapping sediments. However, the effectiveness of such functions is unclear due to the restriction of knowledge on the sedimentation process across the vegetation boundaries. To detect the effects of mangrove forests on sediment transportation and organic carbon sequestration, the granulometric and organic carbon characteristics of mangrove sediments were investigated from three vegetation zones of four typical mangrove habitats on the Leizhou Peninsula coast. Based on our results, sediment transport was often "environmentally sensitive" to the vegetation friction. A transition of the sediment transport mode from the mudflat zone to the interior/fringe zone was often detected from the cumulative frequency curve. The vegetation cover also assists the trapping of material, resulting in a significantly higher concentration of organic carbon in the interior surface sediments. However, the graphic parameters of core sediments reflected a highly temporal variability due to the sedimentation process at different locations. The sediment texture ranges widely from sand to mud, although the sedimentary environments are restricted within the same energy level along the fluvial-marine transition zone. Based on the PCA results, the large variation was mainly attributed to either the mean grain size features or the organic carbon features. A high correlation between the depth and δ13C value also indicated an increasing storage of mangrove-derived organic carbon with time.  相似文献   

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