赤道西太平洋暖池区更新世以来的生源沉积物沉积特征及其古海洋学意义   总被引：3，自引：1，他引：3  

王汝建  成鑫荣  刘传联  翦知  王吉良  李建  武晓光 《海洋地质与第四纪地质》2001,21(4):67-72

赤道西太平洋暖池区中部柱状样MD972140中钙质超微化石氧同位素记录和生物地层学的研究为该柱提供了可靠的年龄框架。氧同位素记录与生源和非生源组分的对比表明，粗组分和碳酸钙含量变化表现为冰期降低，间冰期升高，类似于大西洋型旋回，而蛋白石和非生源组分却与之相反。更新世以来粗组分和碳酸钙含量的变化总体上是由高到低，而蛋白石和非生源组分含量的变化是由低到高，反映了陆源物质输入量和表层水生产力的增加。由此可见，碳酸钙和蛋白石含量的变化主要受到钙质和硅质生物生产力以及陆源物质输入量的控制。氧同位素7期以来，蛋白石含量和硅质微体化石丰度在冰期升高及在间冰期降低的变化反映了表层水生产力的波动和硅质溶解作用的强弱。  相似文献   

Experimental salt weathering of limestones in relation to rock properties     

A. S. Goudie 《地球表面变化过程与地形》1999,24(8):715-724

A total of 21 different types of British and European Mesozoic limestones have been subjected to simulated salt weathering using sodium sulphate (Na₂SO₄) with the following aims: assessment of the relative durabilities of different types of limestone; assessment of the importance of modulus of elasticity and other factors in affecting durability; and assessment of the use of impulse excitation techniques to monitor changes in rock modulus of elasticity. The rocks showed a wide spectrum of durabilities; while rocks with high values of modulus of elasticity, lower water absorption capacities, high densities and low salt uptakes tended to be durable, there were anomalies, the explanation for which probably lies in their pore structures. Non-destructive testing techniques showed that, although the more durable rocks failed to lose weight or to show visual signs of disintegration, their modulus of elasticity values did tend to decline, indicating a loss in strength. Copyright © 1999 John Wiley & Sons, Ltd.  相似文献   

Geochemical characteristics of ores and surface waters for environmental risk assessment in the Pinpet iron deposit,southern Shan State,Myanmar     

Kyaw Zay Ya  Tsubasa Otake  Aoi Koide  Kenzo Sanematsu  Tsutomu Sato 《Resource Geology》2020,70(3):296-308

Mining operations in the Pinpet Fe deposit, which is the second‐largest Fe deposit in Myanmar, are currently suspended, in part because of possible contamination of heavy metals and hazardous elements (e.g., Fe, As, Cu, Zn, and U) into the surrounding aquatic environment and associated public concern. However, a scientific investigation of the source and degree of contamination in streams near the deposit has not yet been conducted. Therefore, we quantified heavy‐metal and hazardous‐element concentrations of stream waters and sediments in stream beds, and measured the speciation and concentration of these metals in deposit Fe ores using the sequential extraction method, to better understand the influence of mining activities on the surrounding environment. Geochemical results for Nan‐tank‐pauk stream and its tributaries indicate that the chemical compositions of their waters are controlled by carbonate bedrock and that no detectable contamination has occurred as a result of mining activity or hematite and limonite ore beneficiation processes in either the wet or dry seasons. All measured heavy‐metal and hazardous‐element concentrations were below the World Health Organization standards for drinking water and the proposed national drinking water quality standards in Myanmar. Bulk chemical compositions of stream‐bed and tailings dam sediments show that As, Zn, and Cu concentrations are similar to those in uncontaminated sediments. Results of bulk mineralogical and chemical analyses of ore samples reveal that some limonite ore samples contain substantial amounts of As (up to 2 wt%). However, sequential extraction results indicate that most (>90%) of the As in these As‐rich ores is hosted in insoluble fractions (e.g., crystalline Fe hydroxides and clays). Therefore, arsenic is unlikely to be released into the aquatic environment by interacting with water during ore beneficiation processes should the mine resume operations.  相似文献   

海洋沉积物/颗粒物在生源要素循环中的作用及生态学功能   总被引：2，自引：1，他引：1  

宋金明  李学刚 《海洋学报》2018,40(10):1-13

海洋沉积物/颗粒物是生源要素循环过程中的关键源与汇,沉积物/颗粒物一方面是海水生源要素的主要归宿,生源要素从溶解态经复杂的生物-化学过程转变为颗粒态,颗粒物质再沉降形成沉积物,另一方面,海洋沉积物/颗粒物经过微生物-浮游动物-底栖生物作用分解形成溶解态的生源要素,并释放到海水中再次被浮游植物利用,进入下一轮循环,所以,海洋沉积物/颗粒物具有异常重要的生态学功能。浮游植物是海水溶解态生源要素的利用者和海源颗粒态生源要素的初始形成者,浮游动物通过摄食浮游植物或其他有机颗粒物可释放出溶解态生源要素或形成更大的颗粒物,颗粒物沉降后形成的沉积物又通过底栖生物摄食-扰动-破碎等过程将颗粒生源要素释放进入水体参与再循环。生态系统不同类群的生物在颗粒生源要素的释放-沉降中所起的作用不同而又相互关联,其中浮游动物-底栖生物的摄食与代谢、微生物参与的分解过程起着非常重要的作用。所以,海洋沉积物/颗粒物生态学功能研究作为支撑海洋环境和资源的持续利用的科学基础,已成为海洋科学的前沿领域,必将获得跨越发展。  相似文献   

夏季珠江口及近岸海域悬浮颗粒物生物硅分析          下载免费PDF全文

俞小勇  徐杰  龙爱民  钟宛宣 《海洋学研究》2018,36(3):67-75

2017年6月在珠江口及近岸海域61个站位采集了悬浮颗粒物生物硅(BSi,biogenic silica)和叶绿素a(Chl a)。利用RAGUENEAU et al(2005)提出的碱提取法测定了悬浮颗粒物生物硅,探讨不同环境条件下BSi浓度以及碱性提取液中岩源硅(LSi,lithogenic silica)的干扰程度。结果显示,Chl a质量浓度范围为0.06~8.64 μg·L^-1,悬浮颗粒物BSi浓度从低于检测限到14.3 μmol·L^-1,LSi浓度范围为0.00~9.56 μmol·L^-1;LSi/(LSi+BSi)比均值为0.38 mol·mol^-1。提取液中测得的Si/Al比均值为2.42 mol·mol^-1,与RAGUENEAU et al(2005)报道值接近。研究区域内的表层BSi反映了硅藻的生物量,与Chl a存在显著线性相关。LSi对BSi测量的干扰程度存在明显的空间差异,总体上近岸BSi和LSi高,LSi/(LSi+BSi)比低;外海BSi和LSi低,LSi/(LSi+BSi)比高;河口内BSi低,LSi高,LSi/(LSi+BSi)比高;上升流区BSi和LSi高,LSi/(LSi+BSi)比高;底层较表层具有更高的LSi和LSi/(LSi+BSi)比。最后,对常用的几种碱提取法在应用时存在的问题作了探讨。  相似文献   

夏季珠江口邻近海域表层浮游植物的碳叶绿素比值及其碳含量     

俞小勇  徐杰  龙爱民  李瑞环  施震  李芊 《海洋学报(英文版)》2020,39(2):123-131

Chlorophyll a(Chl a),particulate organic carbon(POC)and biogenic silica(BSi)were determined in coastal waters adjacent to the Zhujiang(Pearl)River Estuary(ZRE)during summer,in order to examine the C:Chl a ratio of phytoplankton and phytoplankton carbon in the plume-impacted coastal waters during summer,as well as to assess the relative contribution of diatoms to the phytoplankton biomass,by the regression between Chl a,POC and BSi.Our results showed that the C:Chl a ratio(g/g)of phytoplankton was high(up to 142),likely due to high light intensity and nutrient limitation.The river plume input stimulated phytoplankton growth,especially diatoms,resulting in higher relative contribution of phytoplankton carbon(55%)and diatoms(34%)to POC in the plume-impacted region than those(33%and 13%)in high salinity area,respectively.Phytoplankton carbon(up to 538μg/L)in the plume-impacted region was much higher than that(<166μg/L)in high salinity area.Our findings were helpful to improve the biogeochemical model in coastal waters adjacent to the ZRE.  相似文献   

近1000年来西格陵兰荷尔斯泰因斯堡港生物硅指示的海洋生产力变化   总被引：1，自引：1，他引：0  

沙龙滨  李冬玲  刘焱光  吴彬  吴燕妮  Knudsen Karen Luise  李中乔  徐皓 《海洋学报(英文版)》2020,39(9):78-85

We analyzed the biogenic silica(BSi) content and produced a diatom-based summer sea-surface temperature(SST) reconstruction for sediment core GC4 from the Holsteinsborg Dyb, West Greenland. Our aim was to reconstruct marine productivity and climatic fluctuations during the last millennium. Increased BSi content and diatom abundance suggest relatively high marine productively during the interval of AD 1000–1400, corresponding in time to the Medieval Warm Period(MWP). The summer SST reconstruction indicates relatively warm conditions during AD 900–1100, followed by cooling after AD 1100. An extended cooling period during AD 1400–1900 is characterized by prolonged low in reconstructed SST and high sea-ice concentration. The BSi values fluctuated during this period, suggesting varying marine productivity during the Little Ice Age(LIA).There is no significant correlation between the BSi content and SST during the last millennium, suggesting that the summer SST has little influence on marine productively in the Holsteinsborg Dyb. A good correspondence between the BSi content and the element Ti counts in core GC4 suggests that silicate-rich meltwater from the Greenland ice sheet was likely responsible for changes in marine productively in the Holsteinsborg Dyb.  相似文献   

Influence of particle composition on thorium scavenging in the marginal China seas     

YANG Weifeng  CHEN Min  CAO Jianping  QIU Yusheng  ZHANG Run  MA Qiang  TONG Jinlu  YANG Junhong  YANG Zhi  L&#; E 《海洋学报(英文版)》2009,28(2):45-53

Thorium-234 and particle composition (organic matter, biogenic silica, carbonate and lithogenic component) were examined in the East China Sea (ECS) and the northern South China Sea (NSCS) in order to constrain the particle types scavenging thorium isotopes. Good positive correlations between particulate organic matter (POM) or carbonate and thorium-234 in suspended particulate matter (SPM) indicates that POM and carbonate are efficient to scavenge thorium-234. No relationship between biogenic silica and thorium-234 suggests that geochemical behavior of thorium-234 may be not influenced by biogenic silica. A simple model was used to evaluate the affinity of thorium-234 to different particle components. The results show that POM is the most efficient scavenger for thorium-234 in the ECS and the NSCS, followed by carbonate. The authors'' results lend support to the utility of thorium-234 as a proxy of POC and carbonate in the upper layer. However, the strong dependence of thorium scavenging on particle composition challenges thorium-230 as a constant flux proxy.  相似文献   

Early Pliocene Paleoceanography of the Vityaz Fracture Zone, Central Indian Ridge     

M. V. S. GUPTHA Ran adip BANERJEE Lina P. MERGULHAO Priyanka BANERJEE G. PARTHIBAN Manish TEWARI 《《地质学报》英文版》2007,81(4):614-621

Planktic foraminifera from the calcareous substrate of a ferromanganese crust in the Vityaz Fracture Zone （VFZ）, Central Indian Ridge were studied to reconstruct the early Pliocene paleoceanography of this region. Eleven species of planktic foraminifera were encountered, among them Globorotalia menardii, Neogloboquadrina dutertrei, Globigerina bulloides and Globigerinoides tuber are prominent. Predominance of N. dutertrei in the top 3 cm of the carbonate substrate is attributed to an influx of fresh water which eventually triggered their productivity by increasing the nutrient level. The presence of G. bulloides and G. menardii in significant proportions in deeper layers suggests the prevalence of open ocean upwelling. The bulk chemical compositions of the substrate at different depth intervals indicates higher enrichment of trace metals in the upper sections which could have been supplied through oceanic water by the chemical weathering of terrestrial matter during the peak of Pliocene Asian monsoon. Thus, it is concluded that during the early Pliocene the biogenic components of the substrate were distinctly contributed by both upwelling and productivity triggered by an influx of fresh water originating from the intensification of the Asian monsoon during the early Pliocene Period.  相似文献   

Spatiotemporal changes of biogenic elements in the Changjiang River Estuary and adjacent waters in summer over the last decade     

Lu Yang  Yujia Zhang  Xiaoli Wang  Qiulu Wang  Long He  Xiao Li 《海洋学报(英文版)》2023,42(1):83-90

The long-term spatiotemporal changes of surface biogenic elements in the Changjiang River Estuary and adjacent waters during the summer of 2008-2016 were analyzed in this study.The concentrations of dissolved inorganic nitrogen(DIN),soluble reactive phosphate(PO₄^3-) and silicate(SiO₃^2-) were generally stable,with a slight decrease of DIN and PO₄^3-,and a slight increase of SiO₃^2-,which mainly occurred in the e...  相似文献