【作者】 黄婧；

【导师】 孙立广； 王新明；

【作者基本信息】 中国科学技术大学 ， 环境科学， 2011， 博士

【摘要】 阿德雷企鹅和南极毛皮海豹是南大洋食物链顶端捕食者,他们对环境变化的反应敏感,是南极无冰区环境变化的指示计。研究历史时期企鹅、海豹的生态变化有助于更好地认识未来的全球变化对南大洋生态系统的影响。目前对南极企鹅、海豹生态变化的研究主要以野外调查、卫星遥感观测和粪土层标型元素、Sr和N同位素的方法为手段,应用有机地球化学方面的工作还不多。本文选取位于东南极西福尔丘陵阿德雷企鹅粪土沉积剖面DG2、西南极法尔兹半岛毛皮海豹粪土沉积剖面HN1和东南极罗斯岛阿德雷企鹅粪土沉积剖面MB4进行有机地球化学分析,以生物粪土沉积层为载体,利用生物标志物结合地质学方法与古气候学、生态学、动植物学等多学科交叉的方法,研究了环南极三个区域的有机地球化学性质和生态发展历史,结合气候变化和人类文明的发展,利用微观生物地球化学来探索生态、气候与环境变化之间的科学问题,探讨生物对环境的响应和海鸟、海兽对聚居地周围植物生态环境的影响,为研究环南极生态和环南极气候变化提供科学依据,也为更好的预测未来提供基础。涉及的主要内容和结果如下:1.东南极西福尔丘陵企鹅聚居地生态研究对东南极西福尔丘陵Gardner Island阿德雷企鹅粪土沉积剖面DG2开展了有机地球化学分析,研究了企鹅粪土层DG2的烃类、醇类和酸类等生物标志物。DG2沉积剖面的正烷烃以短链为主;脂肪酸组分偶奇优势明显,以C₁₆,C₁₈和C₂₄一元饱和脂肪酸为主;不饱和脂肪酸含量很低,以C_18:1^△9为主,总体表明沉积剖面的沉积来源单一稳定,主要来源可能为淡水湖相沉积的藻类、细菌和水生苔藓输入,无大波动。醇类组分以高浓度的植醇、胆甾烷醇和胆甾醇为主,分别代表了植被和企鹅数量,指示了研究区域历史时期的生态变化。本章利用粪便甾醇恢复了阿德雷企鹅在西福尔丘陵地区8,500年来的数量变化,恢复此地历史时期的生态系统变化,并首次利用C_24:0酸作为水生苔藓的标志物,恢复历史时期水生苔藓的生长状况以及探讨水生苔藓和企鹅数量之间相互消长的关系。2.西南极法尔兹半岛海豹聚居地生态研究对西南极法尔兹半岛毛皮海豹粪土沉积剖面HN1开展了有机地球化学分析,这是首次利用生物标志物的方法来恢复历史时期海豹数量的变化。通过对采自该地区的海豹粪土沉积柱HN1的有机地球化学分析,发现HN1沉积剖面的正烷烃以短链及n-C₂₃为主,主要来源可能为湖相沉积的藻类、细菌和苔藓的输入。脂肪酸组分偶奇优势明显,以C₁₆,C₁₈和C₂₄一元饱和脂肪酸为主,主要来源可能是浮游动物、细菌及苔藓;不饱和脂肪酸含量很低,以C_16:1和C_18:1为主,表明了沉积剖面的沉积源单一稳定,无大波动。醇类组分以高浓度的植物甾醇和粪便甾醇为主,分别代表了植被和海豹粪土沉积的输入,利用粪便甾醇和植醇恢复了该地区上个世纪以来海豹数量的变化和周围植被变化。20世纪上半叶,由于人为的大量捕杀,该地区海豹数量下降, 60年代后期由于人类禁止捕杀海豹,该地区海豹数量得以迅速恢复。该地区上个世纪以来人类活动对海豹数量变化有显著影响。与此同时,气候变暖在过去几十年中使植被和藻类增加,磷虾减少,磷虾数量的减少也影响了海豹数量的变化。3.东南极罗斯岛企鹅聚居地生态研究对东南极罗斯岛企鹅粪土沉积剖面MB4开展了有机地球化学分析,第一次利用生物标志物的方法来恢复该地区历史时期企鹅数量的变化。通过对东南极罗斯岛Cape Bird的企鹅粪土沉积剖面MB4的有机地球化学分析,可以了解到MB4沉积剖面的正烷烃主要分布在C₁₅到C₃₀,以C₁₇、C₂₃和C₂₉为主,主要来源可能为周围环境中的苔藓输入。脂肪酸组分偶奇优势明显,以C₁₆和C₂₄一元饱和脂肪酸为主,主要来源可能是浮游动物、细菌及苔藓。醇类组分以C_28,30一元脂肪醇、植物甾醇和粪便甾醇为主。通过利用生物标志物:胆甾醇+胆甾烷醇、植醇、nC₁₆-ol、nC₂₂-ol和nC₂₈-ol来分别指示企鹅数量、植被状况、藻类、苔藓和地衣的变化,恢复罗斯岛Cape Bird中部地区阿德雷企鹅聚居地1,120年来的生态变化,探讨此地的沉积环境、有机质来源以及环境对此沉积的影响,探讨企鹅生态和自然过程对南大洋生态系统的影响,以及和周围环境之间的反馈关系。4.环南极地区粪土层生物标志物性质对比与分析我们用生物标志物的方法分析了环南极三个沉积剖面:东南极西福尔丘陵Gardner岛、西南极法尔兹半岛和东南极罗斯岛Cape Bird,通过分析这三个生物沉积剖面中的有机生物标志物分布,研究这三个区域沉积物由于周边植被和聚居地动物的不同而造成生物标志物的不同。烃类、脂肪醇和酸类的变化更多的是受到了采样点沉积古环境以及采样环境和古环境中周围植物输入的影响,甾醇类则是受到不同动物粪便来源的影响而显示出不同的标志物,可以对不同的动物粪便来源进行区分并恢复历史时期的生物数量变化。通过对比发现,生物标志物提供了沉积剖面更为全面的信息,可以完善对粪土沉积层性质的了解,加深了对区域生态和环境演变过程的理解。更多还原

【Abstract】 Adélie penguin and fur seal are the top predators in the food chains of Southern Ocean and they are sensitive to the environmental changes. Therefore they are indicators of the Southern Ocean status. Rearches on the historical changes of ecosystems of penguins and seals contribute to a better understanding of the influences of global changes to the ecosystem of Sounthern Ocean. And the current methods of researching on the Antarctic penguins, seals ecological responses are field survey, satellite remote sensing methods, biogeochemical records and the istopes of N and Sr. But the works which are using organic geochemistry method are few.In the present study, we perform organic geochemic analyses on the Adélie penguin ornithogenic sediment core DG2 and MB4 in Vestfold Hills and Ross Island, East Antarctica separately, and fur seal excrement sediment core HN1 in Fieldes Peninsula, combine with geology and ancient climate, ecology, animal and plant science and other interdisciplinary approach, study the organic geochemistry and ecological history of the three regions around the Antarctica. By combine with changes of climate and development of human civilization, we can explore the problems between climate and environmental changes, biological responses to environmental and sea birds, sea animals on the colonies by using micro-ecological biogeochemistry. And these researches provide the scientific basises for future ecological researches and the researches of climate of the Antarctic ring. The main contents are summarized as follows:1. The evolution of penguin colony on Vestfold Hills, East AntarcticaWe collected an ornithogenic sediment core DG2 from Gardner Island in Vestfold Hills, East Antarctica, and reconstructed an 8,500 years variation history of penguin population and vegetation abundance on this island, and examined the evolution of the penguin colony. The results showed that the aliphatic hydrocarbons were mainly consisted of short-chain n-alkanes which likely derived from freshwater algae and bacteria. Meanwhile, the even-carbon fatty acids, such as n-C₁₆, n-C₁₈ and n-C₂₄, dominated alkenoic acids and they principally originated from bacteria, freshwater moss or zooplankton. However, unsaturated fatty acids were predominated by C_18:1 acid from freshwater algae to show good preservation and simple sourses of the sediments but trace amount in it. Furthermore, the concentrations of cholestanol, cholesterol and phytol which came from penguin excrements and vegetation were high in the alcohols and the fluctuations of them in the lake core might respond to the historical changes of penguin populations and vegetations. We used the levels of two molecular markers cholesterol and cholestanol as the proxy indicators of penguin population size. Other molecular markers, including C_24:0 alkenoic acids, C₁₈ n-alkanol and phytol were used as the proxy indicators of aquatic moss, algae, and general vegetation respectively. It’s shown that the growth of algae was mainly affected by the nutritional supply from penguin droppings, so their abundance was positively linked with penguin population. The growth of aquatic moss, however, was controlled more by the degree of water body transparency than by nutrient availability. Because the pollution of water body increased as penguin population grew, aquatic moss abundance showed a seesaw-like relationship with penguin population. These results suggested that penguins played a dominant role in this simple ecosystem in the Antarctic environment. The reconstructed relationship between penguin population and vegetation abundance may offer new insights to understand ancient Antarctic environment and ecology.2. The evolution of seal colony on Fieldes Peninsula, West AntarcticaWe collected a sediment core HN1 from the Fieldes Peninsula of West Antarctica, and performed organic geochemical analysis on it. Short-chain n-alkanes were the main components of aliphatic hydrocarbons, and they were likely derived from algae and bacteria; n-C₂₃ was likely from moss. Fecal sterols and phytol respectively came from seal feces and vegetation, they were dominant in the alcohol compositions, and their fluctuations likely responded to historical changes of the ecosystem near the sediment. The even-carbon fatty acids, such as n-C₁₆, n-C₁₈ and n-C₂₄, dominated the alkenoic acid compositions, and they mainly originated from bacteria, moss and zooplankton. The concentrations of unsaturated fatty acids were low and predominated by C_16:1 and C_18:1 unsaturated acids, and this showed that the sediment was well preserved and had a simple and stable source of organic materials. We used cholesterol, cholestanol, epicoprostanol, coprostanol, and seal hair numbers as the proxy indicators of seal population size and phytol as of general vegetation, and we reconstructed the 20^th century history of variation of the seal population and vegetation abundance on this island. In this study, The sealing industry in the early 20^th century caused the dramatic decline of seal population, and the ban of seal hunting since the 1960s led to its recovery of seal population. The seal population during the past century was primarily controlled by human activities and krill density. The reconstructed relation between seal population and vegetation abundance may offer new insights into Antarctic environment and ecology.3. The evolution of penguin colony on Ross Island, East AntarcticaWe collected an ornithogenic sediment core MB4 from Cape Bird in Ross Island, East Antarctica, and reconstructed an 1,120 years variation history of penguin population and vegetation abundance on this island, and examined the evolution of the penguin colony. The results showed that the aliphatic hydrocarbons were mainly consisted of long-chain n-alkanes which likely derived from mosses. Meanwhile, the even-carbon fatty acids, such as n-C₁₆ and n-C₂₄, dominated alkenoic acids and they principally originated from bacteria, freshwater moss or zooplankton. Furthermore, the concentrations of cholestanol, cholesterol and phytol which came from penguin excrements and vegetation were high in the alcohols and the fluctuations of them in the lake core might respond to the historical changes of penguin populations and vegetations. We used the levels of cholesterol and cholestanol, phytol, nC₁₆-ol, nC₂₂-ol and nC₂₈-ol as the proxy indicators of penguin population size, vegetable, algae, moss and lichen respectively. These results suggested that penguins played a dominant role in this simple ecosystem in the Antarctic environment. The reconstructed relationship between penguin population and vegetation abundance may offer new insights to understand ancient Antarctic environment and ecology.4. The contrast and analysis of biomarkers in different fields on AntarcticaWe analyzed three sediment profiles around Antarctica by using biomarkers: Adélie penguin ornithogenic sediment core DG2 and MB4 in Vestfold Hills and Ross Island, East Antarctica separately, and fur seal excrement sediment core HN1 in Fieldes Peninsula. By analyzing the distribution of biomarkers in the three sediments, we could research on the differents of plants around the research areas and the distribution of differents biomarkers. Hydrocarbons, alcohols and acids are more impacted by the environment and the input of plants. Sterols are impacted by the origines of differental animals’fecals. Therefore sterols can distinguish differental animals and reconstruct the changes of population in history. By comparison, the sedimentary biomarkers provide more comprehensive informations, improve the understanding of sediments, deepen the understanding of the evolutions of regional ecologic and environment.更多还原