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1.
Periplatform surface sediments were studied for carbonate mineralogy in conjunction with analyses of the water column for carbonate chemistry on the eastern Northern Nicaragua Rise (NNR) in the Caribbean Sea. The results show a strong correspondence between variations and disappearance, with increasing water depth, of metastable carbonate minerals (fine aragonite and magnesian calcite) and their respective saturation levels in the overlying waters. Similar correspondence between variations in sediment proportions of fine aragonite and magnesian calcite and their respective saturation levels has previously been established in the Bahamas. There are, however, significant differences between the two areas. The sharp decrease in aragonite content and the measured aragonite saturation level occur at 4000 m in the Bahamas, compared to 1800 m on the eastern NNR. In both areas, magnesian calcite minima correspond to the in situ PCO 2 maxima in the water column. The magnesian calcite minimum, however, is at 950 m in the Bahamas and 750 m on the eastern NNR. Magnesian calcite disappears in the Bahamas at 3800 m and at 2000 m on the eastern NNR. These results demonstrate the importance of the influence of overlying water chemistry on the preservation of metastable carbonate minerals in off-bank periplatform sediments, and they clearly demonstrate the difference in terms of carbonate preservation between the poorly ventilated waters of the Caribbean Sea and the well-oxygenated waters of the adjacent Atlantic Ocean. They also open the possibility of obtaining paleoceanographic information on the depth of the CO 2 maximum (O 2 minimum) and its separation from the aragonite saturation depth in at least some areas. 相似文献
2.
基于渤海表层典型的碳酸盐系统,通过实验室密闭培养实验,分析急性CO 2酸化条件对菲律宾蛤仔( Ruditapes philippinarum) CaCO 3形成速率( G)和CO 2呼吸速率( RC)的影响,以探讨局部海域CO 2酸化的底层海水在潮流或者风海流等因素的驱动下,脉冲式影响贝类栖息地时养殖贝类可能的响应。结果表明,菲律宾蛤仔在急性CO 2酸化条件下发生轻微的钙壳溶解和显著的呼吸抑制。CO 2酸化和菲律宾蛤仔的呼吸作用共同驱动钙壳溶解,溶解速率随 Ω文石下降而升高, G(μmol/(FWg·h))=0.14 × Ω文石-0.49 ( n=12, r=0.95, p<0.01)。活体菲律宾蛤仔钙壳保持稳定的 Ω文石临界值为3.5,而在 Ω文石=1.0的条件下,每天溶解的钙壳相当于贝壳总重的2‰。相较于钙壳溶解, Ω文石改变对菲律宾蛤仔呼吸作用的影响更大, RC(μmol/(FWg·h))=0.27 × Ω文石+0.90 ( n =12, r=0.82, p<0.01)。由于呼吸代谢决定了摄食等各种耗能行为的效率,因此本研究的结果表明,尽管菲律宾蛤仔可以通过摄食等自身调节机制来抵御造成钙壳溶解的环境胁迫,然而这一机制本身就可能受到酸化环境的不良影响。 相似文献
3.
利用free-drift开放反应系统,在恒压力(101.325 kPa)和恒温度(25.0±0.2)℃环境条件下,研究人工海水中二氧化碳分压(pCO2)的变化对方解石和文石的溶解速率及反应级数的影响.研究结果表明:如果溶解实验中pCO2未达到完全平衡,计算得出的反应级数偏小,且反应液pCO2不平衡是造成不同反应阶段反应... 相似文献
4.
The B/Ca ratio of planktonic foraminifer shells has been used as a proxy for reconstructing past ocean carbonate chemistry. However, recent studies have revealed significant uncertainties associated with this proxy, such as whether seawater temperature or [ CO_3~(2-)] is the dominant control on the partition coefficient(K_D) of planktonic foraminiferal B/Ca. To address these uncertainties and thus improve our understanding of the planktonic foraminiferal B/Ca proxy, we analysed B/Ca ratios in the tests of Neogloboquadrina dutertrei(300–355 μm) and Pulleniatina obliquiloculata(355–400 μm) in surface sediment samples from the tropical western Pacific and South China Sea. The relationship between these B/Ca ratios and bottom water calcite saturation states(Δ[ CO_3~(2-)]) is weak, thus suggesting only a small dissolution effect on the B/Ca of the two species. The correlation coefficients(R~2) between the B/Ca ratios of N. dutertrei and P. obliquiloculata and environmental parameters(e.g., temperature, salinity, phosphate, DIC and ALK) in the tropical western Pacific and South China Sea are not high enough to justify using B/Ca ratios as a palaeoenvironmental proxy in the study areas. The significant correlation between K_D values of N. dutertrei and P. obliquiloculata and carbonate system parameters(e.g.,[ CO_3~(2-)], DIC, ALK, pH and [ HCO_3~-]) in the study area reflect chemical links between the K_D denominator and these variables. Based on our surface sediment calibration, an empirical relationship between the K_D of N.dutertrei and temperature is proposed in the tropical western Pacific. We also generated a record of B/Ca ratios in N. dutertrei(300–355 μm) from Core MD06-3052 in the tropical western Pacific over the past 24 ka to evaluate the application of the revised B/Ca proxy method. Based on the reconstructed empirical relationship for B/Ca and subsurface seawater ALK, we estimated subsurface seawater carbonate system parameters in the tropical western Pacific since 24 ka. In general, the estimated subsurface seawater pH and [ CO_3~(2-)] show an increase with time, and the record of subsurface seawater pCO_2 shows a decrease with time, in the tropical western Pacific over the past 24 ka. The consistent trends in subsurface seawater pCO_2 and opal flux during deglaciation may imply that the reported increase in subsurface water pCO_2 in the study area was promoted by enhanced upwelling in the Southern Ocean. 相似文献
5.
Cold-water (<3–11°C) carbonate is the predominant sediment on the Tasmanian shelf. Calcitic skeletal grains (bryozoa, foraminifera, echinoderms, etc.) predominate over aragonitic (gastropods, etc.) ones. Non-skeletal grains are mostly micritic intraclasts with some pellets. Fibrous spherulitic and rhombohedral calcite submarine cements range up to 90% in the bryozoan sand. X-ray analyses show that the bryozoan sand is characterized by a spectrum of calcites (low to high magnesian) and some aragonite. A uniform spread of Mg concentrations from 0.06 to 2.48 wt.% indicates <3–10°C ambient water temperatures. The Mn (10–360 ppm) and Fe (176–2499 ppm) concentrations increase with increasing Mg values due to the formation of impure CaCO3 phases. The Sr content in bryozoan sand (bryozoa = 3200 ppm Sr) decreases with increasing rhombohedral calcite cement, as low Mg-calcite precipitating from 3° C sea water would have 1350 ppm Sr. The bryozoan sand grains with fibrous spherulitic calcite cements have high Sr concentrations (4470–7000 ppm), in the same range as in aragonitic (detected only by X-ray analyses) bryozoan sand grains. The spherulitic calcite cements are either pseudomorphs after original aragonite cements or these calcite cements and aragonite were inverted from fibrous spherulitic vaterite, a predominant CaCO3 polymorph at temperatures <10°C. 相似文献
6.
Ｄｙｎａｍｉｃｓ ａｎａｌｙｓｉｓ ｆｏｒ ｆｌｕｘ ｏｆ ｃａｒｂｏｎ ｄｉｏｘｉｄｅ ａｃｒｏｓｓ ｓｅａｓｕｒｆａｃｅＺｈａｎｇＨｕａｉａｎｄＳｕｎＦｕＡｂｓｔｒａｃｔ：ＴｈｅＣＯ２ｅｘｃｈａｎｇｅｂｅｔｗｅｅｎａｔｍｏｓｐｈｅｒｅａｎｄｓｅａ... 相似文献
7.
The 3rd Chinese National Arctic Research Expedition(CHINARE–Arctic III) was carried out from July to September in 2008. The partial pressure of CO2(pCO2) in the atmosphere and in surface seawater were determined in the Bering Sea during July 11–27, 2008, and a large number of seawater samples were taken for total alkalinity(TA) and total dissolved inorganic carbon(DIC) analysis. The distributions of CO2 parameters in the Bering Sea and their controlling factors were discussed. The pCO2 values in surface seawater presented a drastic variation from 148 to 563 μatm(1 μatm = 1.013 25×10-1 Pa). The lowest pCO2 values were observed near the Bering Sea shelf break while the highest pCO2 existed at the western Bering Strait. The Bering Sea generally acts as a net sink for atmospheric CO2 in summer. The air-sea CO2 fluxes in the Bering Sea shelf, slope, and basin were estimated at-9.4,-16.3, and-5.1 mmol/(m2·d), respectively. The annual uptake of CO2 was about 34 Tg C in the Bering Sea. 相似文献
8.
分析表观耗氧量、滴定碱度及总二氧化碳量等资料来研判红海及亚丁湾间之海水交换。结果显示,红海深层水的方解石及霰石饱和度均比亚丁湾和阿拉伯海深层水的饱和度高。红海全水柱之方解石和霰石都处於过饱和状态,亚丁湾和阿拉伯海中各深度之方解石亦呈过饱和状态,但霰石的饱和探度则大约在500m左右。分析深层水之生物体无机碳与有机碳的分解比值,可以发现此地区深层水中,大约有25％的总二氧化碳增加量是由无机碳酸钙溶解而来。 相似文献
9.
利用4种海-气界面气体传输速率公式对比研究了北太平洋气体传输速率及其CO 2通量的季节变化特征。与单纯依赖风速的算法相比, 考虑波浪影响的气体传输速率和CO 2通量在空间分布和季节变化上具有明显差异。在低纬度地区(0°～30°N), 波浪参数使气体传输速率下降, 海洋对大气CO 2的吸收减少, 而在30°N以北范围内则出现新的气体传输速率高值区, 海洋对大气的吸收增加。进一步研究了黑潮延伸体区域的气候态月平均气体传输速率和CO 2通量。结果表明, 该区域气体传输速率和CO 2通量最大值分别出现于冬季和春季, 引入波浪参数后, 虽然该区域气体传输速率和CO 2通量平均值没有明显差异, 但季节变化强度显著增强。 相似文献
10.
依托2017年8月23日至2017年9月6日在长江口及邻近海域连续走航测得的二氧化碳分压( pCO 2)值,结合温度、盐度、溶解氧等数据,阐述该海域 pCO 2的分布特征,并利用一次大风事件前后一个断面的重复观测数据,讨论天气事件对长江口海-气CO 2通量的影响。夏季长江口及邻近海域表层海水 pCO 2范围为145~929 μatm,总体呈近岸高远岸低的分布特征,在受长江冲淡水影响的区域,海表 pCO 2较低,整体表现为大气CO 2的汇。大风事件(最大风速达9.7 m·s -1)加强了水体的垂直混合,导致近岸区域从大气CO 2的弱源变为强源(CO 2通量从0.2±1.9上升到 55.0±12.4 mmol·m -2·d -1),而远岸区域的碳汇略有加强(CO 2通量从-12.7±2.3变为-16.8±2.5 mmol·m -2·d -1)。因此,在估算东海海-气CO 2通量时,台风、冷空气等短时间尺度天气事件的影响也不容忽视。 相似文献
11.
Consolidated to friable carbonate rocks found in the Lee Stocking Island area in the Exuma Cays include: (1) reef rock, (2) channel stromatolites, (3) shallow-water hardgrounds, (4) beachrock rimming the islands and (5) Pleistocene bedrock. The most common cement fabrics observed are: aragonitic fibers, which include acicular fan-druse and square-tipped coarse fibers cementing beachrock and stromatolites; and an isopachous needle-fiber rim cementing hardgrounds and stromatolites. Less common are high-Mg calcite bladed textures of the reef rock and stromatolites. Two types of blades are present: the more common stubby variety of either high-Mg or low-Mg calcite, and an elongated variety of high-Mg calcite which was found in only three beachrock samples. Aragonitic micrite envelopes usually surround grains in beachrock, hardgrounds and stromatolites, but only in association with fibrous cement. An aragonitic crust cements the surfaces of lime mud beds of the tidal channel, while a high-Mg calcite cryptocrystalline cement occurs in all the rock types. Calcified algal filaments of high-Mg calcite, from the abundant green and blue-green algae in the area, are a primary cement in stromatolites and a secondary cement in hardgrounds and beachrock. A low-Mg calcite equant spar cements the Pleistocene samples and is associated with meteoric diagenesis and cementation of the Pleistocene surface. Cement precipitation coincides with the path of the cool oceanic water from Exuma Sound as it warms and loses CO2 and moves up onto the bank near Lee Stocking with the incoming tide. Cryptocrystalline cement is the first and commonest cement forming to the seaward while platformward, fibrous cements become predominant. As suggested by their crystal size and location on the shelf margin, we think that the reef rock cryptocrystalline material are the fastest forming of the cements, where the incoming oceanic water is more saturated with respect to calcium carbonate and undergoes the most significant warming. The rate of the warming and degassing process is thought to increase in the tidal channel though the cementation rate is thought to fall slightly in response to a reduced availability of calcium carbonate. On the platform interior further warming and degassing are believed to cause cement precipitation and the development of hardgrounds, but these may form at a slower rate than that of the margin, though this rate is still quite high. Cementation gradients occur from the tidal channel to the intertidal zones of: (1) west Norman's Pond Cay, where cement fabric suggests a reduced calcium carbonate availability, and (2) west Lee Stocking Island, where a change in mineralogy suggests a change in water chemistry. Thus, a sequence of cement fabrics and mineralogies can be traced. Micritic textures occur in a more seaward position; fine, fibrous aragonite fibers in a more lagoonal and levee position; and coarser aragonite fibers and Mg-calcite cements in the intertidal and supratidal position. This sequence is thought to track the evolution of the water mass. 相似文献
12.
针对南海北部和吕宋海峡附近海域的海-气CO2通量及其调控问题,研究了2009年3月底至4月中旬在这些海域通过走航观测的方法取得的海-气CO2分压和海表温度、盐度等相关数据。结果表明,在河口、沿岸流以外的南海北部开阔海域,与大气平衡的CO2分压分布在368~380μatm,南低北高,平均值为371μatm;而海表CO2分压分布在293~405μatm,南高北低。南海北部开阔海域的海表CO2分压主要受温度效应调控,也在一定程度上受水团混合、海-气交换、生物活动等非温度效应的影响。在相同水温条件下,黑潮区的海表CO2分压比南海北部的海表CO2分压低。本研究和大多数前人研究的结果都表明,南海北部海盆区域和吕宋海峡西侧海域在春季与大气CO2接近源汇平衡,而非大气CO2的显著源区。 相似文献
13.
基于2012年7月对东海的调查,剖析了其水体中各形态碳(pCO2、DIC、DOC、POC)的区域分布特征,估算了海-气界面CO2的交换通量(FCO2),探讨了影响其交换的主要因素,在此基础上,结合历史资料初步分析了近十几年来该海域海-气界面CO2交换通量的变化趋势。结果表明,2012年7月长江口邻近海域相对南部陆架区具有较低的DIC浓度,而DOC与POC的浓度相对较高。调查区域表层水pCO2变化范围为96.28~577.7μatm(1atm为101 325Pa),平均值为297.6μatm,低值区出现在长江冲淡水区(30°~33°N,123°~125°E),高值区主要分布在东海陆架的南部区域。表层水pCO2主要受控于长江冲淡水的输入和混合(盐度)、台湾暖流以及生物生产等。调查海域2012年7月海-气FCO2平均为(-6.410±7.486)mmol/(m2·d),表现东海在夏季是大气CO2的汇区,区域碳汇强度由强到弱依次为:长江冲淡水区(CDW)、黄东海混合水区(YEMW)、陆架咸淡水混合区(SMW)、近岸上升流区(CUW)和台湾暖流区(TWCW),东海夏季每日吸收大气CO2(以C计)约(18.3±19.8)kt。结合历史资料分析发现,近十几年来东海夏季碳汇强度有增强趋势,CDW区的海-气界面CO2通量平均年增速为-0.814mmol/(m2·d),即海水吸收大气二氧化碳每年增加约54.6kt,是夏季东海碳汇增加的最主要贡献者。 相似文献
14.
工业革命以来,人类活动释放的大量CO2进入大气层,不仅产生严重的温室效应,也使得全球海洋出现酸化的现象。造礁珊瑚被认为是受海水酸化影响最大的类群。本研究以鹿角杯形珊瑚(Pocillopora damicornis)为研究对象,通过气体交换法模拟未来的酸化环境(2100年)研究鹿角杯形珊瑚的钙化率和光合能力(Fv/Fm)对酸化的响应。实验设置两个pH组(分别为7.8和8.1),自然光下进行4周的实验,水温控制在(27.5±1)℃。由于珊瑚等生物的代谢过程(主要是呼吸作用),实验系统的pH昼夜变化显著,酸化处理组和对照组的pH分别介于7.69~7.91和7.99~8.29。鹿角杯形珊瑚的生长率介于1.15%~2.09%/周,酸化对鹿角杯形珊瑚的钙化率和光合效率没有显著的影响,鹿角杯形珊瑚对酸化的敏感度低。对比历史研究数据,本研究的结果进一步表明酸化对造礁珊瑚的影响存在种的特异性。推测鹿角杯形珊瑚对酸化的抗性可能与该珊瑚在有光的条件下能够利用HCO-3以及能够上调钙化位点的pH有关。这种特异性的pH缓冲能力使得珊瑚能维持钙化位点钙质基质高的文石饱和度(Ωarag),因此能以小的额外能耗提高造礁珊瑚的钙化率。 相似文献
15.
ＣａｒｂｏｎａｔｅｃｈｅｍｉｓｔｒｙａｎｄｔｈｅａｎｔｈｒｏｐｏｇｅｎｉｃＣＯ_２ｉｎｔｈｅＳｏｕｔｈＣｈｉｎａＳｅａ￥Ｃｈｅｎ－ＴｕｎｇＡｒｔｈｕｒＣｈｅｎａｎｄＭｉｎｇ－ＨｓｉｕｎｇＨｕａｎｇ（ＲｅｃｅｉｖｅｄＳｅｐｔｅｍｂｅｒ２１，１９９３；ａ?.. 相似文献
16.
周日观测对掌握近海碳酸盐体系变化和海-气CO 2交换过程是必要的，有助于降低碳源汇评估的不确定性。针对北部湾东北部的英罗湾-安铺港海域，于2018年4月和8月利用24 h定点逐时采样观测了该区域表层海水碳酸盐体系及相关要素，分析了春、夏季的表层海水CO 2分压(p CO 2)24 h逐时变化规律及其调控因子。观测结果表明，春、夏季p CO 2变化范围分别为530～628μatm和427～748μatm，平均海-气CO2通量分别为(1.7±0.8)mmol/(m 2·d)和(1.2±0.8)mmol/(m 2·d)，均表现为大气CO 2的弱源。其中春季p CO 2 24 h逐时变化受温度的影响相比夏季更显著，而夏季p CO 2对潮汐作用以及区域内沿岸河流、地下水等淡水汇入引起的生物生产和呼吸代谢过程增强的响应更明显。海水升温主导了春季区域表层高p CO 2的形成，夏季咸淡水的物理混合过程中增... 相似文献
17.
大气CO2浓度升高引起的海洋酸化如何在光变环境下影响大型海藻固碳量的问题,关系到未来海洋初级生产力的变化趋势。为研究大型海藻对CO2浓度升高和光强变化的响应,本文选取浒苔(Ulva prolifera)幼苗为实验材料,探讨其在不同光强下[80、260μmol/(m2·s)]和两种CO2浓度(正常CO2浓度:400μL/L和高CO2浓度:1 000μL/L)下的生理变化。研究发现,在正常CO2浓度、高光条件下,浒苔幼苗的生长最快,超氧化物特化酶(SOD)活性最高,而过氧化氢酶(CAT)活性在低光、高CO2处理下有最大值。光合色素含量和光系统Ⅱ的光化学效率在不同处理间没有显著性差异,但叶绿素a与类胡萝卜素的比值在低光正常CO2处理下有最大值。同时,高光高CO2处理下,浒苔幼苗的可溶性蛋白含量最低。 相似文献
18.
ＣｈｅｍｉｃａｌｃｈａｒａｃｔｅｒｉｓｔｉｃｓａｎｄｅｓｔｉｍａｔｉｏｎｏｎｔｈｅｖｅｒｔｉｃａｌｆｌｕｘｏｆＮ，Ｐ，ＳｉｉｎｕｐｗｅｌｌｉｎｇａｒｅａｏｆＴａｉｗａｎＳｔｒａｉｔ￥ＣｈｅｎＳｈｕｉｔｕａｎｄＲｕａｎＷｕｑｉ（ＦｕｊｉａｎＩｎｓｔｉｔ... 相似文献
19.
海表二氧化碳分压( pCO 2)是指海洋表层水和大气之间的二氧化碳(CO 2)交换处于动态平衡时CO 2的含量, 是描述海-气CO 2交换的一个主要因子。本文利用2008—2014年覆盖南海大部分海域的海表 pCO 2观测资料, 结合现场海表温度和海表盐度以及卫星观测的叶绿素 a数据, 构建了基于多元线性回归方法的分区域反演模型。模型在水深浅于30m的区域均方根误差为5.3μatm, 其余海区均方根误差为10.8μatm, 与前人基于个别航次的有限区域反演结果的均方根误差相当。利用该模型公式和HYbrid Coordinate Ocean Model(HYCOM)再分析海表温、盐数据及MODIS-Aqua卫星观测的叶绿素 a数据进行反演, 得到了时空分辨率为5'×5'的2004—2016年的逐月南海海表 pCO 2数据。该数据能较好地反映南海海表 pCO 2在海表温度影响下, 春夏高、秋冬低的季节变化特征, 与前人基于航次观测的研究结果相似, 表明反演模型具有较高的可信度。进一步分析发现, 南海及邻近海域平均海表 pCO 2具有显著的准十年振荡特征: 2012年附近出现了极小值, 之前表现为降低的趋势, 之后略有升高的趋势。受海表 pCO 2的影响, 南海海盆平均海-气CO 2通量在2012年之前出现了显著降低的趋势, 表明南海释放到大气中的CO 2减少, 并在2007年之后的冬季出现了负值(从碳源变为碳汇), 2012年之后变化较为平缓。热带太平洋年代际振荡引起的南海区域海表盐度变化是造成海表 pCO 2及海-气CO 2通量准十年变化的主要原因。分区分析的结果表明, 南海北部海表 pCO 2变化最为显著, 在南海海表 pCO 2的季节和准十年变化中都起到非常重要的作用。 相似文献
20.
采用船载海?气CO 2连续观测系统于2011年和2014年夏季在琼州海峡开展了现场观测，分析研究了表层海水二氧化碳分压(pCO 2)时空变化及其影响因子。2011年和2014年夏季pCO 2分别为(516±29) μatm和(533±15) μatm，海?气CO 2交换通量分别为(8.4±1.7) mmol/(m2·d)和(4.5±0.4) mmol/(m2·d)，均是大气CO 2的强源，高于相邻及相似海域，主要受控于东口海域上升流和海峡中部狭管效应。2011年夏季东口上升流增大pCO 2的同时也促进了浮游植物繁殖，光合作用吸收水体CO 2，降低了pCO 2，而且受其影响，西口口门附近叶绿素a和溶解氧含量陡增，pCO 2突降。2014年夏季东口海域上升流较弱，且观测海域垂直混合作用显著，pCO 2和溶解氧分布特征与2001年夏季明显不同。海峡中部狭管效应造成水体输运速率大、混合作用强，浮游植物“来不及”生长，pCO 2较高。 相似文献
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