陆架边缘海沉积物有机碳矿化及其对海洋碳循环的影响

边缘海沉积物是海洋重要的碳储库,其内部的碳循环主要是由有机质矿化分解过程来驱动的。有机碳进入边缘海沉积物后,矿化分解为溶解无机碳(DIC)进入沉积物孔隙水并扩散到上层水柱,参与海洋系统碳循环;同时还有部分DIC与钙镁等离子结合形成自生碳酸盐,保存于沉积物碳库。从生物地球化学角度探讨有机质埋藏机制和效率,在此基础上重点综述沉积物硫酸盐还原、产甲烷和甲烷厌氧氧化过程的耦合机制,以及有机质矿化对自生碳酸盐形成的影响等方面的研究进展,以期加深对陆架边缘海沉积物在全球碳循环收支平衡中的作用及其气候环境效应的认识。     

恢复地史时期大气CO2浓度的新指标: 苔藓植物化石

在中国已知最好的苔藓植物化石产地之一河北蔚县, 采集了大量中侏罗世的苔藓植物化石, 选取了3种保存较好的数十块苔类植物化石进行实验室分析处理, 测定了它们的碳同位素组成, 并计算出Δ13C, 运用国际学术界古大气CO₂浓度的最新研究成果, 即通过地质学、植物学、植物生理学、地球化学和概率统计学的多学科交叉研究, 利用苔藓植物化石有机碳同位素判别这一全新指标和重建古大气二氧化碳的模型——BRYOCARB, 恢复出中侏罗世的古大气CO₂浓度约为705(BRYOCARB_NP)或566(BRYOCARB_P)μmol/mol, 结果表明苔藓植物化石是恢复地质历史时期大气CO₂浓度变化的有效新指标.      

末次间冰期以来渭南黄土地区土壤有机碳碳库的演变

冰期-间冰期的陆地碳库变化成为最近十几年来碳循环研究的热点之一,以深海氧同位素、模型模拟和古环境证据等手段展开对不同时间尺度上不同碳库之间碳通量变化研究.土壤碳库的巨大储量导致了土壤碳库的任何微小波动都比陆地生态系统其他碳库更容易影响陆地生态系统碳循环以及大气CO₂浓度,并最终影响到全球气候变化.通过对过去4万年来黄土高原地区土壤有机碳碳库的演变研究发现,深海氧同位素第3阶段期间,土壤有机碳碳密度相对于磁化率在细节上更能够表现出气候的小波动,这一期间的土壤有机碳碳密度快速上升,在较高的水平上多次波动,可能是因为这一时期的气候环境整体上更适宜碳在黄土古土壤中的累积和保存.在末次盛冰期(LGM)时,土壤有机碳碳密度急剧下降,伴随气候的快速波动,其间有一次较大规模的反弹,持续约2 ka,最低值出现在14 ka BP和19 ka BP.对比深海氧同位素曲线,土壤有机碳碳库与其在末次盛冰期和全新世都表现出良好的一致性.而磁化率在大约15 ka BP以后就开始增加,似乎超前于土壤有机碳碳密度和深海氧同位素的增加.并且,在全新世早期到晚期土壤有机碳碳密度经历了逐渐上升继而下降的变化过程,该时段的最高值出现在大约7~5 ka BP.      

泥炭地碳源汇功能与“双碳”目标

自工业革命以来,大气中CO₂浓度快速升高导致了全球变暖,并引发了一系列气候和环境问题。应对气候变化、实现“碳达峰与碳中和”(以下简称“双碳”)已成为世界各国共同倡导的目标;而理解自然系统的碳源汇功能,对实现这一目标具有重要的意义。泥炭地是世界上分布最为广泛的湿地类型,对全球碳循环和气候变化有着十分重要的影响,其在实现“双碳”目标中的重要性受到越来越多的关注,这也使泥炭地碳循环研究成为前沿领域。本文简要回顾了国内外泥炭地碳循环的研究现状,阐述了泥炭地的碳源汇特征(包括CO₂净交换、 CH₄排放、溶解有机碳迁移、碳累积)、变化及驱动机制,并对其在实现“双碳”目标中的作用进行了分析。总体来说,泥炭地碳循环对全球碳源汇估算具有重要的影响,未来需进一步加强对泥炭地分布和碳库的研究,强化泥炭地生态环境演变规律、碳循环-相关过程对气候变化的敏感度以及研究薄弱地区等的针对性研究。在此基础上,科学地可持续管理和恢复退化泥炭地,如人为水文调节,以保持甚至增加其碳汇潜力和储存碳的稳定性,可发挥泥炭地在“双碳”时代的最大碳汇潜力,也将是减缓气候...     

藏南碳酸岩脉成因及其气候效应

始新世末期以来,全球大气CO₂浓度持续下降,但长期以来不清楚为何这一时期全球大气CO₂浓度下降,巨量的大气CO₂赋存于何处。深入研究该问题有助于准确理解未来大气CO₂浓度变化的趋势,特别是有助于进一步评估人类自身碳排放的后果。这一时期,小印度陆块持续与大亚洲陆块汇聚,导致了以喜马拉雅为代表的山脉群和青藏高原的形成。很早就有学者从地球表层碳循环的角度提出了"青藏高原的隆升导致了全球变冷"的观点,但这一观点既没有解释清楚"巨量大气CO₂到何处去"的问题,也没有讨论青藏高原本身向大气圈排放CO₂等问题,因此该观点最近受到了强烈的质疑。这些激烈的争论充分反映了传统的地球表层碳循环研究已不能充分满足当前社会的需求。本文从深部碳循环这个视角重新探讨青藏高原在全球碳循环中的作用。在印度与亚洲陆块持续汇聚期间,以喜马拉雅为代表的巨型山脉快速崛起,然后持续遭受化学风化作用,大量消耗大气CO₂。化学风化的产物堆积在喜马拉雅山前的前陆盆地内,形成了巨量含新生碳酸盐矿物和有机碳的西瓦里克沉积杂岩,随后新生的西瓦里克杂岩又随持续平板俯冲的印度陆壳被带入青藏高原内部,与平板俯冲的印度陆壳共同经历高温变质作用。俯冲板片内的(黑)云母等含水矿物发生脱水,形成花岗岩浆。花岗岩浆再与俯冲的西瓦里克杂岩内的碳酸盐岩发生交代反应,释放出含钙、镁离子、以CO₂和水为主的高温流体,本文称其为壳源火成碳酸岩浆。碳酸岩浆沿张性裂隙上侵、冷凝之后形成藏南的碳酸岩脉。虽然青藏高原内部的火山、温泉等均向大气圈排放CO₂,但所排放的碳均为再循环来自大气圈的碳,并且排放量略小于吸收量,否则消耗大气CO₂所新生的碳酸岩脉就不会在青藏高原内部保存下来。藏南大量晚新生代碳酸岩脉的发现充分说明了喜马拉雅山脉和藏南高原是一个巨大的碳储库,在其形成过程中将巨量大气CO₂转化为流体(岩浆)的形式封存于青藏高原内部,从而大幅降低了大气CO₂浓度,最终导致了全球变冷。上述过程充分说明,大气CO₂浓度的变化实质上是受控于地球内部的构造运动。进一步可推论出,"全球变化"只是一个自然现象,虽然它有独特的运行轨迹,但与人类的碳排放量无因果关系。     

松辽盆地庆深气田天然气成因类型鉴别

通过对松辽盆地徐家围子烃源岩和原油热模拟实验、烷烃气碳同位素组成分析, 认为在高演化阶段单一热力作用可以引起重烃气(δ13C₂ > δ13C₃ > δ13C₄) 碳同位素组成倒转, 但CH₄与C₂H₆(δ13C₁ > δ13C₂) 却很难发生倒转.庆深气田天然气重甲烷碳同位素组成、烷烃气碳同位素完全倒转、高稀有气体同位素组成(R/Ra > 1.0), 说明该气田天然气来源具有多样性.利用R/Ra与CO₂/3He和R/Ra与CH₄/3He关系对庆深气田天然气成因类型进行识别, 认为该气田烷烃气中甲烷有部分为无机成因, 重烃气则为有机成因.该地区高地温梯度导致有机成因重烃气碳同位素组成发生倒转, 而CH₄与C₂H₆碳同位素组成倒转主要与重碳同位素的无机甲烷混入有关.      

海洋直接注入CO2封存技术方法综述

人类活动造成的CO₂排放是全球气候变暖面临的主要挑战之一。CO₂封存有望成为全世界减少碳排放份额最大的单项技术。海洋碳捕获、利用和封存(OCCUS)可以在较短时间内提供最大的碳封存能力,与其他地质封存方法相比更加安全有效。而且,多相态形式的CO₂(气态、液态、固态和水合物)可以在海洋纵深尺度上实现直接注入。海洋碳封存是一项发展潜力巨大、优势明显的新兴碳封存技术,是实现大规模碳减排的重要措施之一,具有广阔的应用前景。因此,笔者等系统地阐述了海洋CO₂直接注入、封存(OCS)的基本原理、技术现状、监测与评估,以及环境方面的影响,并对高效CO₂注入技术,CO₂泄漏的检测、防范与补救技术,以及海洋碳封存的生态后效等方面进行了展望。     

地质封存CO2水岩作用对页岩有机碳的萃取效应研究

CO₂ 水岩相互作用实验研究对于CO₂地质封存以及页岩气开发都具有重要意义。近年来多数研究主要侧重于岩石中矿物成分的反应过程,对于岩石中有机质成分的研究比较有限。本文选取盖层页岩,重点研究CO₂对于页岩中有机碳的萃取效应作用。实验使用高压反应釜在95 ℃和15 MPa条件下进行CO₂ 水页岩反应,同时考查不同的水岩接触方式对反应的影响,实验中分别测试了反应后水体中的溶解性有机碳(DOC)和反应前后岩石表面形态变化(SEM表征)。DOC的测试结果表明,相对于空白对照组高压N₂作用,超临界CO₂体系对于岩石有机碳具有明显的萃取效果,其中在不含水和仅含少量水的体系中,CO₂体系对DOC的萃取量能达到N₂体系的3倍以上,显示超临界CO₂极强的萃取能力。对比不同含水量的实验体系,发现含有少量水的情况下,CO₂对于有机碳的萃取量达到最大,比不含水的体系高出了87%,而这种能力的提高是由于少量极性分子H₂O的加入,能够增强超临界CO₂流体的溶剂化性能导致的。SEM结果也说明了不同的水岩气接触方式对岩石表面形貌具有不同的改造效果。本文实验结果有助于更好认识CO₂地质封存水岩作用及其潜在环境风险。     

冬春季青藏高原北麓河多年冻土活动层中气体CO2浓度分布特征

2005年1~5月在青藏高原北麓河附近的高寒干草原、高寒草甸和高寒草原3种典型草地上进行了不同深度土壤气体采样和CO₂浓度分析.结果表明:土壤剖面的土壤气体CO₂浓度呈现出上低下高的分布特征.在动态变化上,土壤中CO₂浓度在多年冻土活动层春季升温过程中出现一个峰值,经过短暂的降低后随夏季融化过程开始而升高.土壤剖面CO₂浓度与土壤有机碳、重组有机碳、轻组有机碳、水溶性有机碳、植物残体有机碳、微生物碳贮量和土壤温度呈明显的相关关系,在100 cm以上深度与土壤水分呈负相关关系.在整个观测期间,高寒干草原、高寒草原和高寒草甸植被下3种土壤剖面土壤气体CO₂浓度变化范围分别为1 052~3 050 mL·m^-3、3 425~39 144 mL·m^-3和984~12250 mL·m^-3,高于我国塿土CO₂浓度变化范围,也远远高于青藏高原五道梁地区高寒草原土壤气体CO₂浓度变化范围.石灰简育寒冻雏形土和石灰寒冻砂质新成土CO₂浓度变化范围低于国外报道的草地和农田CO₂浓度变化范围;石灰草毡寒冻雏形土CO₂浓度变化范围明显高于国外报道的草地和农田CO₂浓度变化范围.活动层冻结期,土壤CO₂的闭蓄作蓄作用比较明显.由于微地形导致土壤水分条件的差异,夏季融化过程各观测点土壤CO₂浓度开始升高时间存在差异.     

南海北部海马冷泉区表层沉积物的AOM生物标志化合物特征及意义

选取采自南海天然气水合物赋存区海马冷泉,管状蠕虫区（ROV06站位）和贻贝区（HM101站位）的2个表层沉积物柱状样品,提取其中的生物标志化合物,对其种类和稳定碳同位素进行了测定,用以探讨海底表层沉积物中的有机质来源、微生物种群分布及其对冷泉渗漏活动的响应特征. 两个站位的沉积物中均发现了大量与甲烷厌氧氧化古菌（ANME）有关的生物标志物,如2,6,11,15?四甲基十六烷（crocetane）、2,6,10,15,19?五甲基二十烷（PMI）等类异戊二烯烃,古醇（archaeol）、sn2?羟基古醇（sn2?OH?Ar）等,以及来源于硫酸盐还原菌（SRB）的异构/反异构脂肪酸iso?C₁₅和ai?C₁₅等. 这些生物标志物均具有极低的碳同位素特征（古菌生标δ13C值低至-126‰,硫酸盐还原菌生标δ13C值低至?89‰）,表明沉积物中发生了甲烷厌氧氧化作用（AOM）. ROV06和HM101站位沉积物中均检测到了crocetane,大多数sn2?羟基古醇/古醇大于1,同时ai?C₁₅/iso?C₁₅脂肪酸比值小于2,这说明两个站位沉积物中的甲烷厌氧氧化古菌主要以ANME?2/DSS为主,指示甲烷渗漏强度较强. ROV06站位的表层沉积物含有crocetane,但sn2?羟基古醇/古醇小于1,且ai?C_15/iso?C₁₅脂肪酸比值大于2.1,指示了ANME?1/DSS和ANME?2/DSS混合存在的种群特征,说明ROV06站位顶部甲烷渗漏强度有减小的趋势. 根据古菌种群ANME?2化合物对甲烷的碳同位素分馏（Δ:-50‰）及古菌生物标志物（PMI、古醇、sn2?羟基古醇）的平均δ13C值,计算得到甲烷δ13C值（-58‰~-53‰）,显示甲烷为热成因和生物成因混合气. 虽然ROV06和HM101站位的甲烷具有相近的δ13C值,但ROV06站位的SRB生物标志物比HM101站位要更加亏损13C（Δδ13C:18‰）,这可能与管状蠕虫的共生菌（硫氧化菌）吸收硫化物并释放出硫酸盐有关,因为其不断释放出的硫酸盐很可能极大地增强了甲烷厌氧氧化作用,使沉积物中含有更多13C亏损的无机碳.      

The Paleoceanography during the Time with High δ13C of Phanerozoic marine carbonates

Carbon isotopic composition of marine carbonates is a record for various important geological events in the process of earth development and evolution. The carbonates of Carboniferous, Permian and Triassic, as the transition from Paleozoic to Mesozoic-Cenozoic have very high ¹³C value. Taking this as the main point, and combined with the oxygen, strontium isotopic composition in carbonates, distribution of carbonate basin area through geologic time, the correlation of carbon isotopic composition of marine carbonates to sea level change, organic carbon burial flux, exchange of CO₂ content in atmosphere and ocean, and long cycle evolution of the earth ecosystems were approached. The results are shown as follows: ①The interval of ¹³C >3‰ during Phanerozoic was concentrated in Carboniferous, Permian and the beginning of Triassic, but the beginning of Triassic was characterized by higher frequency and larger fluctuations in ¹³C value during a short time, whereas the Carboniferous-Permian presented a continuously stable high ¹³C value, indicating a larger amount of organic carbon accumulation in this time interval. Relatively high ¹⁸O values during this time was also observed, showing a long time of glaciations and cold climate, which suggest a connection among rapid organic carbon burial, cold climate, as well as pCO₂ and pO₂ states of atmosphere. ②The over consumption of atmosphere CO₂ by green plants during the time with high ¹³C of seawater forced CO₂ being transferred from ocean to atmosphere for the balance, but the decrease in the seawater amount and water column pressure caused by the global cooling could weaken dissolution capacity of CO₂ in seawater and carbon storage of marine carbonates, and also reduce the carbonate sedimentary rate and decrease the carbonate basin area globally from Devonian to Carboniferous and Permian. During the middle-late Permian carbonate was widely replaced by siliceous sediments even though in shallow carbonate platform, which resulted in the decrease of marine invertebrates, suggesting the Permian chert event should be global. ③The Phanerozoic ⁸⁷Sr/⁸⁶Sr trend of seawater showed a sharp fall in Permian and drop to a minimum at the end of the Permian, indicting input of strontium from the submarine hydrothermal systems (mantle flux). Such process should accompany with a supplement of CO₂ from deep earth to atmosphere and ocean system, but the process associated with widespread volcanism and rises of earth’s surface temperature pricked up the mass extinction during the time of end Permian. ④Cold climate and increase of continental icecap volume, the amalgamation of northern Africa and Laurentia continentals were the main reasons responsible for the sea level drop, but the water consumption result from the significantly increased accumulation of organic carbon should also be one of the reasons for the sea level drop on the order of tens of meters. ⑤The mass extinction at the end Permian was an inevitable event in the process of earth system adjustment. It was difficult for marine invertebrates to survive because of the continuously rapid burial of organic carbon, and of the decrease of sea water amount and its dissolution ability to CO₂. At last, at the end of Paleozoic, the supplement of CO₂ to atmosphere and ocean by widely magma activities resulted in a high temperature of earth surface and intensified mass extinction.     

Key Scientific Problems and Challenges of Studying Carbon Cycle Mechanism in Pacific Sector of the Arctic

Challenged by the enormous pressure to reduce the global carbon emission, it is expected that the Arctic Ocean could absorb additional atmospheric CO₂ with the retreating of sea-ice. The Chukchi Sea and adjacent waters, characterized by the highest carbon fixation in the global ocean and large carbon flux into the deep-ocean for sequestration, make substantial contributions to carbon cycling in the entire Arctic Ocean. Understanding the response mechanism of carbon cycling in this region to the rapidly changing environment is the foundation for the prediction of carbon sink in the Arctic Ocean. However, the response of carbon absorption and storage to climate change is still controversial, and the main controlling factors of the carbon cycle process remain unclear.Thus, to establish high-resolution coupled ocean-ice-carbon models can explore the influence of sea ice retreat on atmospheric CO₂ and the vertical sinking carbon fluxes in Chukchi Sea, estimate the effectiveness of growing inflow and slope upwelling on carbon sink/source patterns, discuss the response of deep-ocean carbon sequestration to the changing environment, and evaluate the effectiveness of continental shelf pump in the Chukchi Sea as well as its role in the global carbon sink. Based on the challenge for the research of the Chukchi Sea carbon cycle research with rapidly changing climate, the basic ideas of establishing Arctic Ocean carbon cycling model as well as its key scientific issues to be resolved were proposed.     

人类巨量碳排放后果分析: 来自青藏高原综合调查的启示

人类巨量碳排放究竟导致什么后果,争议颇大,只有深入研究始新世以来大气CO₂浓度与环境变化,才有可能正确认识未来人类自身巨量碳排放之后果。大量研究揭示出: 从始新世到渐新世末期,大气CO₂浓度大幅下降,全球变冷,形成了大陆冰川; 中新世至今,大气CO₂浓度在低浓度背景之下长周期缓慢下降。当前尚不清楚何种机制主导了这一变化过程,也不清楚形成大陆冰川的水来自何方。为此,从青藏高原深部碳循环、表层水循环和环境变化的角度探讨这些问题,再分析未来人类巨量碳排放之后果。青藏高原在生长、隆升过程中,通过硅酸岩化学风化、植物光合作用、陆内俯冲(深埋)、水岩反应等方式,持续将巨量大气CO₂转化为富含碳元素的固、流体,封存在青藏高原新生的厚地壳之中,大幅降低了大气CO₂浓度,导致了全球变冷、大陆内陆(含青藏高原,下同)表层失水变干,形成了大陆冰川。渐新世—中新世之交,青藏高原生长到改变大气环流的规模,形成了亚洲季风,大陆内陆进一步荒漠化,捕获CO₂的量大幅下降,并与青藏高原内部所释放CO₂的量达到了准动态平衡,这是中新世以来大气CO₂浓度变化的主要机制。人类巨量碳排放彻底扭转了大气CO₂浓度长周期缓慢下降的趋势,大陆冰川因全球变暖所形成的液态水不会长期停留在海洋里,而以大气降水的方式重新回到干冷的大陆内陆,青藏高原将因此再次成为巨型水塔,缓解30多亿人的清洁饮用水问题。持续生长的高原和当前干冷荒漠化的大陆内陆通过前述多种方式固化人类排放的巨量CO₂,导致未来大气CO₂浓度在较高浓度背景下保持稳定,届时沙漠变绿洲,黄土高原变成有机质丰富的黑土高原,人居环境大幅改善; 但在盆地内部,PM2.5难以扩散,易形成雾霾。全球平均海平面因海水热膨胀而缓慢上升,上升速率约为1 mm/a。水主要在大陆冰川与内陆表层之间循环,与海平面升降之间没有因果关系。因此,人类巨量碳排放所导致的全球变暖对于人类自身的发展是利大于弊。     

基性-超基性岩碳酸盐化固碳效应研究进展

人为排放CO₂导致全球气候变暖已经对人类生存和发展造成威胁,碳捕获与封存是世界公认的实现碳减排的主要途径之一。基性-超基性岩碳酸盐化固碳作为地质碳汇之一,是一种经济、安全且长久的碳捕获与封存方式,引起了国际社会越来越多的重视。本文阐述了自然条件下基性-超基性岩碳酸盐化反应过程,分析其固碳机理和影响基性-超基性岩碳酸盐化速率的主要因素。在此基础上,梳理并总结了目前国际上基性-超基性岩固碳技术的研究进展和典型应用实例,认为全球广泛分布的基性-超基性岩具有巨大的固碳潜力。该技术的推广和应用将对未来大气CO₂减排具有重要意义。     

海洋酸化对颗石藻的影响

工业革命以来人类活动产生了大量二氧化碳气体（CO2）并释放到大气中。CO2溶于海水,造成海水pH值降低,改变海洋碳酸系统的平衡。海洋酸化对海洋生态系统特别是钙化生物构成威胁。颗石藻作为主要的钙化浮游生物,在海洋碳循环过程中起着重要的作用。大多数培养实验表明CO2浓度上升会促进颗石藻光合作用。而海洋酸化对不同种或不同品系颗石藻钙化作用产生不同的影响。     

Marine Carbon Sequestration: Current Situation,Problems and Future

Abuse of fossil energy resources results in the excessive discharge of greenhouse gases, especially CO₂, enhancing the trend of global climate warming. Carbon sequestration is an important method to lower the increasing rate of CO₂ concentration in the atmosphere. Marine carbon sequestration is a novel idea for reducing CO₂ emission, and its reservoir mainly includes seawater and submarine sediment, which not only possess a great potential capacity of carbon sequestration, but also have high safety in relation to continental reservoirs. In this paper, we expounded the technique principle and mechanisms of marine carbon sequestration, potential capacity and time duration of marine carbon sequestration, main factors influencing marine carbon sequestration, CO₂ injection technique, impacts on marine biota from over emission of CO₂ and technique monitoring the leakage of CO₂. Finally, a prospect of marine carbon sequestration was proposed, and its hot topics were accordingly pointed out.     

甲烷氧化与氨氧化微生物及其耦合功能

甲烷氧化与氨氧化过程分别对控制温室气体甲烷和氧化亚氮方面有着特殊作用,土壤及湿地等环境中的甲烷氧化菌和氨氧化菌在生态系统碳、氮生物循环中扮演着重要的角色。论述了甲烷氧化与氨氧化过程的微生物学机制,甲烷氧化菌和氨氧化菌的群落结构变化,分析了甲烷氧化菌和氨氧化菌在碳、氮循环以及它们在控制重要温室气体排放中的环境功能,阐述了甲烷氧化菌和氨氧化菌的关联作用机制。以期深入揭示甲烷氧化菌与氨氧化菌的空间分异与耦合机制,为深入探讨这类微生物的生态机制和环境功能提供科学线索。     

Estimating the carbon transfer between the ocean, atmosphere and the terrestrial biosphere since the last glacial maximum

Carbon dioxide records from polar ice cores and marine ocean sediments indicate that the last glacial maximum (LGM) atmosphere CO₂ content was 80–90 ppm lower than the mid-Holocene. This represents a transfer of over 160 GtC into the atmosphere since the LGM. Palaeovegetation studies suggest that up to 1350 GtC was transferred from the oceans to the terrestrial biosphere at the end of the last glacial. Evidence from carbon isotopes in deep sea sediments, however, indicates a smaller shift of between 400 and 700 GtC. To understand the functioning of the carbon cycle this apparent discrepancy needs to be resolved. Thus, older data have been reassessed, new data provided and the potential errors of both methods estimated. New estimates of the expansion of terrestrial biomass between the LGM and mid-Holocene are 700 GtC ± > 300 GtC, using the ocean carbon isotope-based method, compared with of 1100 GtC ± > 500 GtC using the palaeovegetation estimate. If these estimates of the carbon shift to the terrestrial biosphere are equilibrated with the dissolved carbon in the oceans, and the CaCO₃ compensation of the ocean is taken into account, then the glacial atmospheric CO₂ would have been between 50 (± 30) ppm and 95 (± 50) ppm higher. The glacial atmosphere therefore should have had a CO₂ partial pressure of between 330 and 375 μatm. Hence, a rise of between 130 and 175 μatm in atmospheric CO₂, rather than 80 μatm, at the end of the last glacial must be accounted for.     

基性、超基性岩: 二氧化碳地质封存的新途径

CO₂地质封存是控制全球CO₂净排放量的有效手段.自然界存在大量基性、超基性岩石的碳酸盐风化作用, 与CO₂反应生成稳定的碳酸盐矿物.影响基性、超基性岩石与CO₂反应速率的因素有温度、压力、pH值、流体流动速率以及与矿物接触的表面积等.矿物在反应过程中放热可以使碳酸盐化体系进入自我加热的良性循环, 同时控制流体的流动速率可以保持最佳温度并使反应速率最大化.蛇绿岩中的橄榄岩、大陆玄武岩和深海玄武岩在地球表层广泛分布, 可贮存大量CO₂.目前研究表明此方法在技术上可行, 经济成本上有优势.因此, 基性、超基性岩石具有封存CO₂的巨大潜力, 可以作为地质封存CO₂的新途径.      

Review on Researches of Aragonite Saturation State in the Southern Ocean:A Key Parameter of Southern Ocean Acidification

The Southern Ocean is a strong sink for atmospheric CO₂, making it especially vulnerable to ocean acidification (OA). The aragonite saturation state (Ω_arg) of seawater has been used as an index for the estimation of OA, which plays a critical role in evaluating the living environment of marine calcified organisms. However, it is very difficult to perform the studies of OA and Ω_arg in the Southern Ocean due to its harsh climate. Therefore, in order to better understand the OA and its further influences, the advances of Ω_arg studies were summarized in the oceans surrounding the Antarctica. Significant spatial and temporal variations of surface seawater Ω_arg are demonstrated in the Southern Ocean. In general, the surface seawater Ω_arg shows a lower value in the off-shore areas than in the open oceans. And, Ω_arg also exhibits a strong seasonal cycle with a higher value in summer than in winter. The distributions of Ω_arg in vertical water column generally present a declining tendency from surface to bottom. In addition, the shoaling of Ω_arg horizon at high latitude could be attributed to the ventilation and upwelling of deep waters in the Southern Ocean. There are many factors that could impact the Ω_arg in the Southern Ocean, including sea ice melting, sea-air CO₂ exchange, biological activities and hydrological processes, etc. Finally, the future changes and key scientific problems of OA in the Southern Ocean are proposed.