沉积岩中无机CO2热模拟实验研究

结合三水盆地的地质特点，分析了无机CO₂热模拟实验研究的可能性，进行了不同条件下的模拟试验和相关的分析测试，提出了无机CO₂生成量和转化率的概念和计算方法。从实验结果来看：含有一定量碳酸盐矿物的沉积岩，在一定温度下可转化形成相当数量的无机CO₂，无机CO₂转化率越高，岩石中碳酸盐矿物越容易转化生成无机CO₂；相同热成熟度条件下，Ⅱ型干酪根生成有机CO₂的量较Ⅲ型的少；CO₂中碳同位素与CO₂的成因密切相关，随有机质热成熟度的增加，同种类型有机质生成的有机CO₂相对富集¹³C；无机CO₂较有机CO₂的碳同位素明显富集¹³C，随水介质的pH值降低，无机CO₂气含量、模拟温度及时间的增加，无机CO₂相对富集¹³C。实验研究结果为CO₂成因研究及其资源评价提供了实验依据。     

腾冲新生代火山区温泉CO2气体排放通量研究

近期研究表明,不仅火山喷发期会向当时的大气圈输送大量的温室气体,火山间歇期同样会释放大量的温室气体。在火山活动间歇期,火山区主要以喷气孔、温(热)泉以及土壤微渗漏等形式向大气圈释放温室气体。腾冲是我国重要的新生代火山区,同时也是重要的水热活动区,那里出露大量的温泉,然而目前未见腾冲火山区温泉气体排放通量的研究报道。本文利用数字皂膜通量仪测量了腾冲新生代火山区温泉中CO₂的排放通量。研究结果表明,腾冲新生代火山区温泉向当今大气圈输送的CO₂通量达3.58×10³ t·a^-1,相当于意大利锡耶纳Bassoleto地热区温泉中CO₂的排放规模。腾冲火山区温泉的CO₂释放通量主要受深部岩浆囊、断裂分布、地下水循环、围岩成分等多方面因素的影响。本文根据温泉中CO₂的排放特征,将腾冲温泉分为南北两区,南区温泉CO₂通量远高于北区的温泉,热海地热区的通量为腾冲CO₂通量的最大值。在北温泉区,CO₂通量主要受控于断裂的分布;而在南温泉区,除受到断裂控制外,热海地热区底部的岩浆囊及其与围岩的相互作用成为CO₂气体的重要物质来源,同时高温的岩浆囊为温泉及CO₂的形成提供了重要热源。     

中国东部CO2气地球化学特征及其气藏分布

中国东部CO₂气田(藏)发育广泛,分布复杂。本文对中国东部松辽、渤海湾、苏北、三水、东海、珠江口、莺琼、北部湾等盆地和内蒙古商都地区以及部分现代构造岩浆活动区CO₂气田(藏)和气苗中CO₂的地球化学特征进行了分析和研究,探讨了中国东部CO₂气的成因、来源及分布。中国东部CO₂气的含量主要分布区间为0~10%,其次为90%~100%,呈现典型的U字型。δ¹³C_CO2值则呈现典型的单峰式分布,峰值区间为-6‰~-4‰。CO₂含量、δ¹³C_CO2值和R/Ra值综合表明,中国东部高含CO₂气以幔源无机成因为主,混有部分有机成因气和(或)壳源无机气。中国东部已发现的36个无机成因CO₂气田(藏)在空间分布上与新近纪及第四纪北西西向玄武岩活动带展布一致,深大断裂和岩浆活动是无机成因CO₂富集、运移和分布最重要、最直接的两大主控因素。     

土壤碳及其在地球表层系统碳循环中的意义

本文回顾了近１０年来国内外对土壤碳研究的主要进展,分析了土壤碳的移动性及其影响因素,着重针对陆地系统碳汇饱和问题介绍了土壤碳对大气CO²源汇效应的碳转移过程及其在地球表层系统碳循环中的作用,指出应加强对土壤碳转移及其对全球变化的响应、土壤碳固存对大气CO²调控的机制和动态的研究,以便为缓解陆地系统碳汇饱和提供科学依据。     

新疆罗北洼地湖相沉积物有机碳同位素的变化序列及其古环境意义

测定了新疆罗布泊地区湖相沉积物CK-2钻孔样品的总有机碳含量（TOC）及其同位素组成、碳酸盐含量和C/N比值等环境代用指标,以及石膏矿物的质谱-铀系年龄。测试结果表明,20～9kaB.P.期间沉积物δ¹³C_org.在-23.4‰～-16.1‰之间波动且阶段性明显,与TOC呈现良好的相关关系,整体变化趋势同南极Dome C冰芯中记录的全球大气CO₂浓度一致;C/N比值表明有机碳来源主要是陆生高等植物。因此大气CO₂浓度变化是影响20～9kaB.P.期间罗布泊湖相沉积物δ¹³C_org.值变化的主导因素,周围山体上C₃/C₄植物相对生物量的变化则是另一重要因素。依据δ¹³C_org.的变化序列将此时间段湖区古环境的演化分成6个阶段:20.0～14.1kaB.P.期间受到末次盛冰期的影响,气温偏低,湖水丰沛;14.1～13.3kaB.P.是一个气候不稳定期,冷暖波动较频繁,但以暖为趋势;13.3～12.8kaB.P.期间经历了一段冷期,于12.8kaB.P.结束了末次冰期,随后气候开始转暖至11.8kaB.P.;其后气温再次变冷并维持到10kaB.P.;最后从10kaB.P.进入全新世暖期。δ¹³C_org.序列明显向偏负方向变化,表明该地区变暖的趋势相当明显。罗布泊地区日益干旱化是全球气候变化的结果,尤其是受到全球CO₂浓度的不断升高所制约。     

土壤碳循环研究进展

土壤碳是陆地碳库的主要组成部分,全球土壤有机碳总量达1270 Gt。气候变化影响植物生长、植物碎屑分解速率以及土壤—大气碳通量,这对大气CO₂含量有重要影响。土壤有机质模型是研究生态系统尺度土壤碳循环的唯一可用工具,目前已开发出多种。大量研究表明,¹⁴Ｃ测试是研究土壤有机碳组成及驻留时间的重要手段,土壤有机碳由一系列具不同更新时间的组分构成。土壤粒级组成、矿物特征及土体结构等内在因素制约土壤有机碳存量及状态,对于长时间尺度碳的更新具有重要意义。研究不同气候带土壤有机碳储量及动态变化特征,可为预测未来农、林生态系统变化提供理论依据。     

增江颗粒有机碳同位素的AMS研究初报

全球河流每年向海洋输送约1Gt(10¹⁵g)的碳,其中40%为有机碳。然而,在海洋沉积物中却难以寻找到足量的陆地碳的生物地球化学标记[1]。显然,陆地碳在河流搬运过程中经历了复杂的生物地球化学变化,乃至“踪迹全无”。河流有机碳可大体上划分为颗粒态(POC)和溶解态(DOC)两种基本类型。就全球范围讲,河流输送的POC和DOC在数量上相当或DOC略高些。但在一些高浑浊的河流,尤其是亚洲季风区的河流中,POC在有机碳中却占绝对优势。如珠江干流水体中POCDOC比值高达5.0左右^[2]。因此,亚洲季风区河流中所搬运的POC对其注入水域的生物地球化学过程影响深远。河流有机质的来源复     

太湖及其周围河流中N2O的空间分布与释放通量

本次研究选择中国东部一个生态和环境空间分异极大的浅水湖泊（太湖）以及周围河流,分别于2003年7月和9月两次采集湖水和河水样品,分析其中的N₂O浓度,并利用扩散模型公式估算水-气界面N₂O交换通量。结果显示N₂O饱和度的空间变化从70％不饱和到2708％过饱和变化范围很大。N₂O饱和度的空间分布,N₂O与CH₄、无机氮、TDS（总溶解固体物质）之间的相关性都表明：   太湖重度富营养区N₂O的产生极大地受到人为N输入的影响。然而,初步的通量分析显示湖泊N₂O的释放因子不超过0.63％,小于河流中的默认值,N₂O产率也略低于水环境中的平均值,太湖以面积为权重的释放通量平均值并不高,在7月和9月分别为14.0μmol/m²·d和9.7μmol/m²·d。这些结果表明流域人为N输入对整个湖泊N₂O的促进作用是有限的,预计未来湖泊N₂O释放不会因为人为活动增加而出现大幅度增加的状况。流域内各生态景观N₂O释放量的比较,也表明富营养湖泊总体上仍然是一个十分有限的大气N₂O释放源。相反,太湖周围河流存在较大的N₂O释放速率,在7月和9月估算的N₂O释放通量分别为142.1μmol/m²·d和28.8μmol/m²·d。将这一释放速率推广到整个流域后,预计河网的N₂O释放量将占到耕作土壤的10％～50％,显示了河流对区域N₂O质量平衡具有较重要的影响。     

西安灞河流域现代岩溶作用与CO2吸收量

本文探讨了灞河流域岩溶特征、CO²估算方法和CO²吸收量。观测资料表明,灞河流 域河水中ｐＨ值在冬春季高,夏秋季低,而ＨＣＯ３含量通常与ｐＨ相反。河水和黄土地下水中 ｐＨ值、ＨＣＯ３等化学成分含量与北方南部石灰岩区岩溶水基本相同,表明该区现代岩溶作用 明显,黄土地层也在不断吸收CO²,并对全球碳循环有重要影响。雨水富含CO²,其中约有 ８２％的CO²被岩溶过程吸收,１８％左右的随河水流失。根据一个流域CO²输入量和输出量,可 以计算岩溶过程中 CO²吸收量。计算表明,灞河流域现代岩溶过程中每年吸收的 CO²约为５６３２．８ｔ。     

全球变化条件下的土壤呼吸效应

土壤呼吸是陆地植物固定CO₂尔后又释放CO₂返回大气的主要途径，是与全球变化有关的一个重要过程。综述了全球变化下CO₂浓度上升、全球增温、耕作方式的改变及氮沉降增加的土壤呼吸效应。大气CO₂浓度的上升将增加土壤中CO₂的释放通量，同时将促进土壤的碳吸存；在全球增温的情形下，土壤可能向大气中释放更多的CO₂，传统的土地利用方式可能是引发温室气体CO₂产生的重要原因，所有这些全球变化对土壤呼吸的作用具有不确定性。认为土壤碳库的碳储量增加并不能减缓21世纪大气CO₂浓度的上升。据此讨论了该问题的对策并提出了今后土壤呼吸的一些研究方向。其中强调，尽管森林土壤碳固定能力有限，但植树造林、森林保护是一项缓解大气CO₂上升的可行性对策；基于现有田间尺度CO₂通量测定在不确定性方面的进展，今后应继续朝大尺度田间和模拟程序方面努力；着重回答全球变化条件下的土壤呼吸过程机理；区分土壤呼吸的不同来源以及弄清土壤呼吸黑箱系统中土壤微生物及土壤动物的功能。当然，土壤呼吸的测定方法尚有待改善。     

论岩溶作用对全球碳循环的意义与碳汇效应——兼对《对<中国岩溶作用产生的大气CO2碳汇分区估算>一文的商榷》的答复

岩溶作用促进大气二氧化碳汇过程不仅局限于碳酸盐岩地区,而是涉及全球陆地地质岩石地区,因此以前仅考虑岩溶面积计算的岩溶碳汇量偏低,需要以河流流域为单元全面计算全球岩溶碳汇效应。除了产生河流溶解无机碳被带入海洋外,岩溶作用还可通过水体生物吸收形成颗粒有机碳以及在岩溶土壤中固定有机碳等方式形成碳汇,因此,岩溶地质过程固碳形式多样。其中,仅全球水生生物固定岩溶水重碳酸根产生的有机碳近0.5Gt,生态恢复可促进岩溶土壤有机碳固定及岩溶流域碳汇,我国西南石漠化治理工程至少可增加岩溶碳汇2~3亿t,如果重视岩溶增汇技术的应用,全球岩溶碳汇效应将非常显著。所以,岩溶碳汇研究意义重大,岩溶碳汇效应更不可忽略。      

Modern carbon burial in Lake Qinghai,China

The quantification of carbon burial in lake sediments, and carbon fluxes derived from different origins are crucial to understand modern lacustrine carbon budgets, and to assess the role of lakes in the global carbon cycle. In this study, we estimated carbon burial in the sediment of Lake Qinghai, the largest inland lake in China, and the carbon fluxes derived from different origins. We find that: (1) The organic carbon burial rate in lake sediment is approximately 7.23 g m⁻² a⁻¹, which is comparable to rates documented in many large lakes worldwide. We determined that the flux of riverine particulate organic carbon (POC) is approximately 10 times higher than that of dissolved organic carbon (DOC). Organic matter in lake sediments is primarily derived from POC in lake water, of which approximately 80% is of terrestrial origin. (2) The inorganic carbon burial rate in lake sediment is slightly higher than that of organic carbon. The flux of riverine dissolved inorganic carbon (DIC) is approximately 20 times that of DOC, and more than 70% of the riverine DIC is drawn directly and/or indirectly from atmospheric CO₂. (3) Both DIC and DOC are concentrated in lake water, suggesting that the lake serves as a sink for both organic and inorganic carbon over long term timescales. (4) Our analysis suggests that the carbon burial rates in Lake Qinghai would be much higher in warmer climatic periods than in cold ones, implying a growing role in the global carbon cycle under a continued global warming scenario.     

西江流域的有机碳侵蚀通量

在西江下游的马口水文站对径流进行了4个季节的有机碳采样分析。研究表明,西江径流有机碳的断面构成在各个季节均较为一致;季节性变化表现为,有机碳和悬浮物含量随流量的增加而增加。随着水体悬浮物含量的增加,悬浮物的有机碳含量呈对数趋势降低。西江流域的有机碳侵蚀通量为10.18×106gC/km2·yr.,是全球外流域有机碳侵蚀通量的2～3倍,其中以颗粒有机碳的侵蚀通量为主,达到8.30×106gC/km2·yr.,溶解有机碳的侵蚀通量为1.88×106gC/km2·yr.。反映了流域内较强的机械剥蚀过程,这与西江流域典型的季风气候、较大的地形高差,以及农业耕作历史长久、土地利用强度较大等因素有关。     

Carbon Isotopic Constrains on the Sources and Controls of the Terrestrial Carbon Transported in the Four Large Rivers in China

The Changjiang， Huanghe， Zhujiang and Heilongjiang are the four largest rivers in China and they transport large amount of fresh water and terrigenous materials， including both inorganic and organic carbon into the ocean. The sources of the terrestrial carbon transported in the four rivers， however， have not been well constrained and compared. In this study， we used carbon isotopes （¹³C and ¹⁴C） combined with concentration measurements to investigate and compare the sources and fluxes of Dissolved Inorganic Carbon （DIC）， Particulate Inorganic Carbon （PIC）， Dissolved Organic Carbon （DOC） and Particulate Organic Carbon （POC） in the four rivers. The contributions of the potential sources to both DIC and DOC were quantitatively calculated using a dual isotope and three end member model. The results showed that the concentrations and isotope characteristics of the carbon pools in the river depended largely on the geological setting， surrounding environment and the anthropogenic influence of the drainage basins. Compared with other large rivers in the world， the concentrations of DIC in the Changjiang， Huanghe and Zhujiang were higher， but the DIC fluxes in the Huanghe and Zhujiang were lower. The DOC concentrations in the Heilongjiang River were higher and lower in the other three rivers compared with the average value of the world largest 25 rivers. The Changjiang， Huanghe and Zhujiang all transport millennia aged carbon. The old riverine DIC reflects the influence of chemical weathering of carbonate rocks and the old DOC reflects influence mainly from pre-aged soil OC. These ancient terrestrial carbon discharged by the rivers could have significant effects on the carbon cycle and ecosystems in the China's marginal seas.     

珠江马口站,河口站断面水体有机碳含量的季节变化

１９９７年７月份和１１月份对北河口站和西江马口站水体有机碳含量进行了两次采样分析。结果表明;两江水体的颗粒有机碳含量在不同 均高于溶解有机碳含量,这与全球河流以溶解有机碳为主的平均格局显著不同。溶解有机碳,颗粒有机碳含量以及总有机碳含量均不文季节的变化而变化,汛期含量高于平水期。悬浮物中有机碳的含量的随悬浮物含量的增加,也即流域土壤机械侵蚀强度的加强而降低,这种现象与全球河流的总体趋势一致。汛期水     

Carbon Fluxes and Sinks: the Consumption of Atmospheric and Soil CO2 by Carbonate Rock Dissolution

Carbonate rock outcrops cover 9%–16% of the continental area and are the principal source of the dissolved inorganic carbon (DIC) transferred by rivers to the oceans, a consequence their dissolution. Current estimations suggest that the flux falls between 0.1–0.6 PgC/a. Taking the intermediate value (0.3 PgC/a), it is equal to 18% of current estimates of the terrestrial vegetation net carbon sink and 38% of the soil carbon sink. In China, the carbon flux from carbonate rock dissolution is estimated to be 0.016 PgC/a, which accounts for 21%, 87.5%–150% and 2.3 times of the forest, shrub and grassland net carbon sinks respectively, as well as 23%–40% of the soil carbon sink flux. Carbonate dissolution is sensitive to environmental and climatic changes, the rate being closely correlated with precipitation, temperature, also with soil and vegetation cover. HCO3- in the water is affected by hydrophyte photosynthesis, resulting in part of the HCO3? being converted into DOC and POC, which may enhance the potential of carbon sequestration by carbonate rock dissolution. The possible turnover time of this carbon is roughly equal to that of the sea water cycle (2000a). The uptake of atmospheric/soil CO2 by carbonate rock dissolution thus plays an important role in the global carbon cycle, being one of the most important sinks. A major research need is to better evaluate the net effect of this sink in comparison to an oceanic source from carbonate mineral precipitation.     

土壤发生性碳酸盐碳稳定性同位素模型及其应用

干旱、半干旱地区土壤无机碳库比有机碳库大2~5倍,无机碳库及其周转在该地区土壤碳平衡中具有重要意义。土壤发生性碳酸盐是土壤发育过程的产物,与岩生性碳酸盐溶解/沉积平衡、土壤有机碳分解CO2的再转化密切相关。发生性碳酸盐碳稳定性同位素主要由土壤CO2的碳同位素组成决定,可以用描述不饱和层气体质量传递的扩散—生成模型模拟。在土壤碳酸盐体系（土壤CO2(g)、碳酸盐和土壤溶液）处于同位素平衡状态时,根据生物过程产生的分子扩散以及碳酸盐化学平衡反应的分馏模型,发生性碳酸盐δ13C值比有机质δ13C值大14‰~16‰。扩散—生成模型和/或分馏模型可以用于鉴定和定量化分散态发生性碳酸盐组分、区分土壤碳酸盐悬膜上发生性碳酸盐的比例,并可用于定量评价土地利用管理措施对碳酸盐溶解/沉积平衡的影响,这在全球碳循环研究中具有重要意义。     

岩溶系统中土壤氮肥施用对岩溶碳汇的影响

有资料显示陆地碳酸盐岩风化消耗大气CO2的碳通量与世界森林碳汇通量量级相当。但农业地区过量施用氮肥形成的硝酸对碳酸盐岩的溶解会减弱岩溶碳汇效应,其量可达到7%~38%,而适量施用氮肥在增加农作物产量的同时,能降低土壤C/N比,增加土壤微生物活性,促进有机物料分解,从而提高土壤CO2浓度,提高土下碳酸盐岩的溶解速率。因此,要从两方面分析岩溶系统中土壤氮肥施用对岩溶碳汇效应的影响。同时,岩溶区碳酸盐岩风化形成的土壤具有较高的pH值及盐基饱和度,对H+有较强的缓冲作用,可能是导致自然条件下,河流中溶解无机碳(DIC)与水体中钙、镁等离子并不守恒的原因之一,因此,运用端元法可能过高估算了硝酸对碳酸盐岩的溶解量。岩溶区土壤环境中硝化作用产生的硝酸到底多少能对碳酸盐岩产生溶蚀,并影响到岩溶碳汇效应还有待研究。应结合土壤本身的特性及河流生物地球化学过程,综合研究不同施氮水平、土壤硝化产酸及其影响下的土下碳酸盐岩溶解及碳汇效应过程,客观评价岩溶区土壤氮肥施用对岩溶碳汇的影响,并寻求适宜氮肥施用量及促进岩溶碳循环,提高岩溶碳汇效应的技术方法。      

乌裕尔河流域颗粒有机碳的来源：碳同位素证据

以2008、2009年所采集的乌裕尔河9个点位水体中的悬浮物为研究对象,对丰、枯水期颗粒有机碳（POC）含量、碳同位素组成（^13C、^14C）及表观年龄进行了系统测试与分析,以期探讨河流中颗粒有机碳来源与流域土壤侵蚀的关系。研究结果表明,该河流中颗粒有机碳（POC）主要来源于未受玉米残体及根系输入影响的深层土壤,且土...     

Global significance of the carbon cycle in the karst dynamic system: evidence from geological and ecological processes

On the basis of proposing the existence of a karst carbon cycle and carbon sink at a watershed scale, this paper provides four pieces of evidence for the integration of geology and ecology during the carbon cycle processes in the karst dynamic system, and estimated the karst carbon sink effect using the methods of comparative monitoring of paired watersheds and the carbon stable isotope tracer technique. The results of the soil carbon cycle in Maocun, Guilin, showed that the soil carbon cycle in the karst area, the weathering and dissolution of carbonate rocks under the soil, resulted in a lower soil respiration of 25% in the karst area than in a non-karst area (sandstone and shale), and the carbon isotope results indicated that 13.46% of the heavy carbon of the limestone is involved in the soil carbon cycle. The comparative monitoring results in paired watersheds, suggesting that the HCO₃^- concentration in a karst spring is 10 times that of a rivulet in a non-karst area, while the concentration of inorganic carbon flux is 23.8 times. With both chemical stoichiometry and carbon stable isotopes, the proportion of carbon in karst springs derived from carbonate rocks was found to be 58.52% and 37.65% respectively. The comparison on carbon exchange and isotopes at the water-gas interface between the granite and carbonate rock basins in the Li River showed that the CO₂ emission of the karst water is 10.92 times that of the allogenic water from the non-karst area, while the carbon isotope of HCO₃^- in karst water is lighter by 8.62‰. However, this does not mean that the karst water body has a larger carbon source effect. On the contrary, it means the karst water body has a greater karst carbon sink effect. When the karst subterranean stream in Zhaidi, Guilin, is exposed at the surface, carbon-rich karst water stimulated the growth of aquatic plants. The values of carbon stable isotopes in the same species of submerged plants gradually becomes heavier and heavier, and the 512 m flow process has a maximum range of 15.46‰. The calculation results showed that 12.52% of inorganic carbon is converted into organic carbon. According to the data that has been published, the global karst carbon sink flux was estimated to be 0.53-0.58 PgC/a, equivalent to 31.18%-34.41% of the global forest carbon sink flux. In the meanwhile, the karst carbon sink flux in China was calculated to be 0.051 PgC/a, accounting for 68% of its forest carbon sink flux.