Dissolution kinetics of biogenic silica from the water column to the sediments

Stirred flow-through experiments were conducted for the first time with planktonic biogenic silica (BSi). We investigated the dissolution kinetics of uncleaned and chemically cleaned BSi collected in ocean surface water, sediment traps, and sediments from the Norwegian Sea, the Southern Ocean, and the Arabian Sea. The solubility at 2°C is rather constant (1000 to 1200 μM). The dissolution rates are, however, highly variable, declining with water depth, and phytoplankton reactivity is two to three orders of magnitude higher than pure siliceous oozes. The reactivity decrease correlates well with an increase in the integrated peak intensity ratios of Si-O-Si/Si-OH measured by Fourier transform infrared (FTIR) spectroscopy. The removal of organic or inorganic coatings enhance the reactivity by at least an order of magnitude. Atomic Al/Si ratios of 0.03 to 0.08 in sedimentary diatom frustules decrease significantly to 0.02 as a result of removal of inorganic coatings and detritals present. Near equilibrium, the dissolution rates exhibit a linear dependence on the degree of undersaturation. At higher degrees of undersaturation—that is, at low concentrations of dissolved silica—the dissolution rates of uncleaned samples define a nonlinear trend.The nonlinear kinetics imply that the dissolution of natural BSi is strongly accelerated in silica-depleted surface waters. The FTIR results suggest that internal condensation reactions reduce the amount of surface reaction sites and are partly responsible for the reactivity decrease with depth. The high content of Al in sedimentary BSi is likely caused by precipitation of dissolved silica with Al dissolved from minerals in sediment. Nonbiogenic silica as coatings or detritals are partly responsible for the solubility and reactivity decrease of BSi in sediments. One order of magnitude different rate constants measured in Norwegian Sea and Southern Ocean sediment trap material support the so-called opal paradox—that is, high BSi accumulation rates in sediments in spite of low BSi production rates in surface waters of the Southern Ocean.     

Production and pelagic dissolution of biogenic silica in the Southern Ocean

Vertical distributions of particulate silica, and of production and dissolution rates of biogenic silica, were determined on two N-S transects across the Pacific sector of the Antarctic Circumpolar Current during the austral spring of 1978. Particulate silica profiles showed elevated levels in surface water and near the bottom, with low (35–110 nmol Si · 1^?1) and vertically uniform values through the intervening water column. Both the particulate silica content of the upper 200 m and the production rate of biogenic silica in the photic zone increased from north to south, reaching their highest values near the edge of the receding pack ice. A significant, but variable, fraction (18–58%) of the biogenic silica produced in the surface layer was redissolving in the upper 90–98 m. Net production of biogenic silica in the surface layer (production minus dissolution) was proceeding at a mean rate of ca. 2 mmol Si · m^?2 · day^?1. This is ca. 4 times greater than the most recent estimate of the mean accumulation rate of siliceous sediments beneath the ACC. We estimate, based on mass balance, that the mean dissolution rate of biogenic silica in subsurface water column in the Southern Ocean is 1.2–2.9 mmol Si · m^?2 · day^?1.     

Solubility and dissolution rate of silica in acid fluoride solutions

We performed 57 batch reactor experiments in acidic fluoride solutions to measure the dissolution rate of quartz. These rate data along with rate data from published studies were fit using multiple linear regression to produce the following non-unique rate law for quartz

where 10^−5.13 < a_HF < 10^1.60, −0.28 < pH < 7.18, and 298 < T < 373 K. Similarly, 97 amorphous silica dissolution rate data from published studies were fit by multiple linear regression to produce the following non-unique rate law for amorphous silica

where 10^−2.37 < a_HF < 10^1.61, −0.32 < pH < 4.76 and 296 < T < 343 K. Regression of the rates versus other combinations of solution species, e.g.  + H⁺, F⁻ + H⁺, HF + , HF + F⁻, or  + F⁻, produced equally good fits. Any of these rate laws can be interpreted to mean that the rate-determining step for silica dissolution in fluoride solutions involves a coordinated attack of a Lewis acid, on the bridging O atom and a Lewis base on the Si atom. This allows a redistribution of electrons from the Si–O bond to form a O–H group and a Si–FH group.     

On the relationship between silica and carbonate diagenesis in deep-sea sediments

Silica diagenesis and carbonate diagenesis are interrelated. This is confirmed by observations of DSDP Sites 462, 463, 465, 466, and 577. Carbonate sediments containing chert (1) tend to be more indurated and display more advanced diagenetic alterations, regardless of sub-bottom depth; and (2) microfossil components are more strongly affected (overgrown and/or dissolved), while the amount of micritic particles and larger, euhedral calcite crystals is greater. In addition, mass physical properties, porosity in particular, vary more widely in sediment sections containing chert. Furthermore, in the studied similarly composed sediments recrystallization of biogenic opal is indicated by a significant reduction of the specific surface area, reaching a minimum value when quartz is formed.One possible mechanism involved is the production of «surplus« dissolved carbonate created by the replacement of carbonate material by silica during the process of chert formation and silicification. The «extra« carbonate is then available for precipitation as overgrowths and cement outside the chert nodules and silicified zones. Hence silica diagenesis, if it occurs early enough in the sediment, bears some influence on carbonate diagenesis. It is therefore suggested that silica diagenesis be added to the list of factors included in the «diagenetic potential« equation ofSchlanger &Douglas (1974).

---

Zusammenfassung Die Diagenese von biogenem Silikat und Karbonat steht in engem Zusammenhang, wie Beobachtungen an Sedimenten der DSDP Sites 462, 463, 465, 466 und 577 zeigen. Karbonatische Sedimente, die biogenes SiO₂ enthalten, zeichnen sich aus durch (1) größere Verfestigung und stärkere diagenetische Veränderungen — unabhängig von der Tiefe im Sediment, (2) mehr Lösung und Überwuchs an Mikrofossil-Komponenten, (3) höheren Anteil mikritischer Partikel wie auch größerer idiomorpher Kalzitkristalle, (4) stärkere Variation der sedimentphysikalischen Eigenschaften, speziell der Porosität und damit zusammenhängender Parameter.Die Umkristallisation des biogenen SiO₂ führt in ähnlich Zusammengesetzen Sedimenten zu einer drastischen Abnahme der spezifischen Oberfläche. Minimalwerte werden erreicht, wenn sich Quarz bildet.Diagenetisch wichtig ist die Produktion von zusätzlichem Karbonat durch die Silizifizierung von Karbonatschalen. Dieses »Überschuß«-Karbonat wird dann als Überwuchs, Zement oder außen an den »Hornstein«-Aggregaten gefällt. Demzufolge beeinflußt die Diagenese von biogenem SiO₂ auch die Karbonatdiagenese. Daher ist es sinnvoll, die Diagenese von biogenem SiO₂ mit zu den Faktoren zu rechnen, die das »diagenetische Potential« — wie esSchlanger &Douglas (1974) definierten — ausmachen.

---

Résumé L'étude de sédiments provenant des sites DSDP 462, 463, 465, 466 et 577 montre qu'il existe une relation entre la diagenèse de la silice et celle du carbonate biogéniques. Les sédiments carbonatés qui renferment de la silice biogémque présentent: 1) une induration plus marquée et des modifications diagénétiques plus poussées — et ce indépendamment de la profondeur sous la surface du fond; 2) une dissolution et/ou un accroissement plus développés des micro-fossiles; 3) une plus grande teneur en particules micritiques et une plus grande taille des calcites idiomorphes; 4) un éventail plus large de leurs propriétés physiques, particulièrement de la porosité et des paramètres qui en dépendent.La cristallisation de l'opale biogénique, dans des sédiments de compositions semblables, se traduit par une réduction drastique de la surface spécifique, qui atteint une valeur minimale lorsque du quartz est formé.Un rôle diagénétique important est joué par l'excès de carbonate dissous engendré par la silicification de coquilles carbonatées; cet excès de carbonate est dès lors disponible pour la précipitation des auréoles d'accroissement et du ciment hors des nodules de chert et des zones silicifiées. Il s'ensuit que la diagenèse du SiO₂ biogénique influence la diagenèse du carbonate. Il conviendrait dès lors d'ajouter la diagenèse de la silice à la liste des facteurs qui interviennent dans l'équation du «potentiel diagénétique» deSchlanger etDouglas (1974).

---

462, 463, 465, 466 577, . , , : 1) , ; 2) ; 3) , 4) , . SiO₂ . . . »« , , « ». , .. «, 1974 Schlanger & Douglas.

     

Diffusion of ions in sea water and in deep-sea sediments

The tracer-diffusion coefficient of ions in water, D_j⁰, and in sea water, $\text{D}{}_{\mathrm{j}}{}^1$, differ by no more than zero to 8 per cent. When sea water diffuses into a dilute solution of water, in order to maintain the electro-neutrality, the average diffusion coefficients of major cations become greater but of major anions smaller than their respective $\text{D}{}_{\mathrm{j}}{}^1$ or D_j⁰ values. The tracer diffusion coefficients of ions in deep-sea sediments, D_j,sed., can be related to $\text{D}{}_{\mathrm{j}}{}^1$ by $\text{D}{}_{\mathrm{j,sed.}}\text{= D}{}_{\mathrm{j}}{}^1\text{·}\text{α}\text{θ}{}^2$, where θ is the tortuosity of the bulk sediment and a a constant close to one.     

Calcium carbonate dissolution history in late quaternary deep-sea sediments,Western Gulf of Mexico

Calcium carbonate dissolution has been studied in eight piston cores from the western Gulf of Mexico ranging in depth from 965 to 3630. The degree of dissolution throughout the cores was determined by studies of foraminiferal test fragmentation, benthonic foraminiferal abudance, calcium carbonate concentration, and various relationships between solution-resistant and solution-susceptible species. The paleoclimatic history recorded in these cores is similar to those defined previously in the Gulf of Mexico and equatorial Atlantic. Two mesgascopically distinct ash layers and well-defined planktonic foraminiferal subzones permit precise intercore correlation of dissolution horizons. All cores demonstrate intense dissolution during several subzones, especially during the early-middle Y, X1, and W1. Other less consistent dissolution horizons occur in various cores. Sedimentation rates increase while calcite concentrations decrease during glacial episodes suggesting increased dilution by terrigenous materials. Despite this, glacial episodes show greater dissolution and worse preservation of foraminiferal tests. Therefore, increased dissolution of calcium carbonate during glacial episodes must be a function of some mechanism that more than compensates for the increased rate of burial by terrigenous sediments. Dissolution is dissolution processes are not responsible for the observed effects. The oxidation of organic material may be the primary mechanism controlling the dissolution of calcium carbonate in the western Gulf of Mexico.     

深海沉积物中的稀土矿产资源研究进展

近年发现,太平洋和印度洋的深海盆地中存在大量富含稀土的深海沉积物。主要类型为多金属软泥、沸石黏土和远洋黏土,其中的全稀土含量(∑REY,∑REE+Y)为400×10-6~2000×10-6,最高可达6600×10-6,重稀土含量(HREE)已达到或超过中国南方离子吸附型矿床的重稀土品位两倍以上,是潜在的新型稀土资源,具有重要的经济价值。目前不少学者对富稀土的深海沉积物进行了大量地球化学及部分矿物学的工作,认为多金属软泥中的稀土元素多赋存于与海底热液作用有关的铁锰氧化物和氢氧化物中,而沸石黏土和远洋黏土中稀土元素的富集则与磷酸盐的混入密切相关,其稀土元素主要存在于与磷灰石成分相当的生物鱼骨屑中。深海黏土的北美页岩标准化稀土配分模式与海水相似,表明其中的稀土元素主要来自于海水,REY富集成矿可能主要受控于磷灰石早期成岩阶段,期间稀土元素未发生分异。尽管近些年对深海沉积物中的稀土元素研究取得了不少成果,但是,对于沉积物中的稀土富集机制及影响因素等问题仍然需要更加深入的研究。作为稀土资源大国,为了争取我国在国际海底稀土资源竞争中的话语权,维护中国的稀土利益,中国应加紧开展相关的稀土资源勘查和潜力评价。     

Oxidative dissolution potential of biogenic and abiogenic TcO2 in subsurface sediments

Technetium-99 (Tc) is an important fission product contaminant associated with sites of nuclear fuels reprocessing and geologic nuclear waste disposal. Tc is highly mobile in its most oxidized state and less mobile in the reduced form [Tc(IV)O₂·nH₂O]. Here we investigate the potential for oxidation of Tc(IV) that was heterogeneously reduced by reaction with biogenic Fe(II) in two sediments differing in mineralogy and aggregation state; unconsolidated Pliocene-age fluvial sediment from the upper Ringold (RG) Formation at the Hanford Site and a clay-rich saprolite from the Field Research Center (FRC) background site on the Oak Ridge Site. Both sediments contained Fe(III) and Mn(III/IV) as redox active phases, but FRC also contained mass-dominant Fe-phyllosilicates of different types. Shewanella putrefaciens CN32 reduced Mn(III/IV) oxides and generated Fe(II) that was reactive with Tc(VII) in heat-killed, bioreduced sediment. After bioreduction and heat-killing, biogenic Fe(II) in the FRC exceeded that in RG by a factor of two. More rapid reduction rates were observed in the RG that had lower biogenic Fe(II), and less particle aggregation. EXAFS measurements indicated that the primary reduction product was a TcO₂-like phase in both sediments. The biogenic redox product Tc(IV) oxidized rapidly and completely in RG when contacted with air. Oxidation, in contrast, was slow and incomplete in the FRC, in spite of similar molecular scale speciation of Tc compared to RG. X-ray microprobe, electron microprobe, X-ray absorption spectroscopy, and micro X-ray diffraction were applied to the whole sediment and isolated Tc-containing particles. These analyses revealed that non-oxidizable Tc(IV) in the FRC existed as complexes with octahedral Fe(III) within intra-grain domains of 50-100 μm-sized, Fe-containing micas presumptively identified as celadonite. The markedly slower oxidation rates in FRC as compared to RG were attributed to mass-transfer-limited migration of O₂ into intra-aggregate and intraparticle domains where Tc(IV) existed; and the formation of unique, oxidation-resistant, intragrain Tc(IV)-Fe(III) molecular species.     

The dissolution kinetics of biogenic calcium carbonates in seawater

Dissolution rate as a function of degree of undersaturation was measured on shells of individual species of coccoliths and foraminifera, various size fractions of sediment from the Ontong-Java Plateau and the Rio Grande Rise, a collection of large pteropods, and on synthetic calcite and aragonite powder.Results of the study indicate that all biogenic and synthetic calcium carbonate follows the rate law $\text{R\% = k\%(1 ? Ω)}{}^{\mathrm{n}}$ where $\text{Ω  [Ca}{}^{\mathrm{2+}}\text{][CO}{}_3{}^{\mathrm{2?}}\text{]/K'}{}_{\mathrm{sp}}$ and K'_sp is the apparent solubility product of calcite or aragonitic seawater. In the case of all calcite samples, n_c = 4.5, while for aragonitic samples n_a = 4.2. The ‘rate constant’, k%, varies widely between samples and in many cases is inversely correlated with grain size. However, the individual species of coccoliths, E. huxleyi and C. neohelis, which were cultured in the laboratory appear not to follow this rule, with dissolution rates an order to magnitude lower than expected.     

A method for quantitative evaluation of carbonate dissolution in deep-sea sediments and its application to paleoceanographic reconstruction

A method is proposed by which the degree of attrition of the tests of certain foraminifera species, such as Globorotalia menardii and Globorotalia tumida, is used to “scale” the amount of CaCO₃ that has been dissolved from sediment. The scale is calibrated experimentally in the laboratory. The method has been applied to three calcareous cores from the Pacific and the Indian Oceans. It is shown that the original CaCO₃ contents in these cores were high (82–95%) and relatively uniform compared to the present down-core values. About 65 to 85% of the originally deposited CaCO₃ has been dissolved, corresponding to dissolution rates on the order of 0.1-0.3 moles/cm²/yr. These results indicate that appreciable solution could have occurred on sea floor rich in calcareous sediments and that the variation in CaCO₃ content in a core may have resulted largely from dissolution. The difference in the degree of solution between glacial and interglacial sediments in these cores is not so distinct, with ? 10% less intense dissolution during glacial times on the average. However, the dissolution minimum occurring around the late Wisconsin glaciation (10,000–20,000 yr B.P.) previously noted in several cores elsewhere is confirmed. At that time, near the site of core M70 PC-20 in the southwest Pacific, the $\text{CO}{}_3{}^{\mathrm{2?}}$ concentration of the bottom water is estimated to have been approximately 5% higher than the present value, and the calcite lysocline was about 300 m deeper. To evaluate possible variations in CaCO₃ deposition rate across the glacial-interglacial transitions requires precise age control, which the present study lacks.     

Distribution and sources of carbon,nitrogen, phosphorus and biogenic silica in the sediments of Chilika lagoon

The present study investigated the spatial and vertical distribution of organic carbon (OC), total nitrogen (TN), total phosphorus (TP) and biogenic silica (BSi) in the sedimentary environments of Asia’s largest brackish water lagoon. Surface and core sediments were collected from various locations of the Chilika lagoon and were analysed for grain-size distribution and major elements in order to understand their distribution and sources. Sand is the dominant fraction followed by silt + clay. Primary production within the lagoon, terrestrial input from river discharge and anthropogenic activities in the vicinity of the lagoon control the distribution of OC, TN, TP and BSi in the surface as well as in the core sediments. Low C/N ratios in the surface sediments (3.49–3.41) and cores (4–11.86) suggest that phytoplankton and macroalgae may be major contributors of organic matter (OM) in the lagoon. BSi is mainly associated with the mud fraction. Core C5 from Balugaon region shows the highest concentration of OC ranging from 0.58–2.34%, especially in the upper 30 cm, due to direct discharge of large amounts of untreated sewage into the lagoon. The study highlights that Chilika is a dynamic ecosystem with a large contribution of OM by autochthonous sources with some input from anthropogenic sources as well.     

The distribution of ash in Icelandic lake sediments and the relative importance of mixing and erosion processes

During the Holocene the volcano Hekla explosively emitted highly silicic tephra on four occasions. The ash was widely dispersed by the wind. Distinctive light-coloured ash layers are now to be seen in the peats of Northern Iceland. Ash from the 1104 AD eruption was carried as far as Scandinavia. The most recent three tephra are preserved in the top 6 m of sediment in Lake Svinavatn. Chemical data from the sediment of Lake Svinavatn, which lies near the north coast of Iceland 170 km from Hekla, reveal the presence of silicic ash above the tephra visible to the naked eye. Unlike the vertical spread of ash in ocean sediment cores which results from biological mixing effects, the upwards spread of ash in the Svinavatn lake sediment cores appears to have been produced by erosion of ash from the lake catchment in the decades following the eruptions. The variations in concentrations of 11 elements, as determined by neutron activation analysis, can be explained by an exponentially decreasing input from catchment erosion. The additional input to each of the three Hekla ash layers was in the region of 3% of the ash which fell on the Svinavatn catchment.     

Biogeochemical processes in the water column of the Caspian Sea in November 2008

Doklady Earth Sciences -     

Effect of orthophosphate on the dissolution kinetics of biogenic magnesian calcites

The dissolution behavior of two biogenic Mg-calcites, the echinoid, Tripneustes (12 mol% MgCO₃), and the red alga, Neogoniolithon (18 mol% MgCO₃ plus brucite), was studied using free-drift methods in distilled water and phosphate-spiked solutions at 25°C and P_CO2 = 1 atm. Small concentrations of phosphate strongly inhibit dissolution rates. Inhibition increases with increased phosphate levels and with approach toward saturation. Near saturation, dissolution rates are reduced by 10³ by the presence of 0.6 μmol adsorbed-P/m². The magnitude of phosphate inhibition is similar to that observed for low-Mg calcite, and like calcite, the mechanism of inhibition is probably by adsorption of P at surface kink sites. Phosphate appears to inhibit removal of Mg and Ca equally during Mg-calcite dissolution. Rates of brucite dissolution are unaffected by phosphate.Mg-calcites containing >8.5 mol% MgCO₃ should be thermodynamically unstable relative to aragonite in most natural waters. Recent work, however, shows that in contrast to its effect on the behavior of Mg-calcites. phosphate does not inhibit aragonite dissolution. The presence of phosphate might thus reverse the relative stability of these two minerals during diagenesis of shallow marine carbonate sediments.     

Estimation of authigenic alteration of biogenic and reactive silica in Pearl River estuarine sediments using wet-chemical digestion methods

The extent of authigenic alteration of biogenic and reactive silica in Pearl River estuarine sediments has been estimated using wet-chemical digestion methods. Results show relatively constant distributions of biogenic and reactive Si horizontally and vertically. Based on three core measurements, the biogenic and total reactive Si average 77.91 and 264.77 μmol Si g⁻¹, respectively. Their extents of authigenic alteration are correspondingly estimated as ~55.6 and ~70.6%. The average biogenic Si accumulation rate is calculated as 1.91 × 10⁹ mol Si year⁻¹, which translates into storage of ~7.15% of the annual riverine dissolved silica input. By contrast, the total reactive Si accumulation rate is as high as 6.49 × 10⁹ mol Si year⁻¹, improving annual riverine silicic acid storage to ~24.19%. Detailed investigation is required for a good understanding of early diagenetic process of biogenic and reactive silica in this subtropical area.     

Influence of hydrodynamic regime on the mineral composition of deep-sea sediments

The composition of sand-silt and pelite fractions of deep-sea sediments deposited under different hydrodynamic conditions was studied. Assemblages of clastic, clayey, biogenic, and authigenic minerals formed under the influence of surface and bottom currents were traced. It is shown that biogenic opal, fine-dispersed celestobarite, and authigenic protosyngenetic ferromanganese micronodules, which are composed of only manganese phases, represent indicators of cyclonic gyres characterized by enhanced bioproductivity. Collophane (bone detritus), phillipsite, palagonite, and large celestobarite crystals prevail in mineral assemblages below the anticyclonic gyres, whereas ore micronodules are depleted in manganese. Surface and bottom currents control the distribution of clastic (terrigenous edaphogenic, terrestrial-volcanogenic) and clay minerals, as well as biogenic opal in the form of Ethmodiscus frustules in sediments. Edaphogenic mineral assemblages represent the reliable indicators of bottom currents.     

The 1912 earthquake in South Baikal: traces in bottom sediments and gas release into the water column

Large earthquakes took place in southern Cisbaikalia in the first half of 1912. They might have caused a mass release of gas (methane?) into the water column of Lake Baikal and the atmosphere near Sharyzhalgai station of the Circum-Baikal Railroad. This phenomenon was observed in August 1912 by the residents as rising water columns several meters high and reported in the regional press.To find traces of this event, core was recovered from bottom sediments at a depth of 1300 m in winter 2010. The depth interval 1–8.7 cm is a homogeneous layer, no more than 100 years old (²¹⁰Pb dating). The sediments here are poor in SiO_2biog but richer in Corg than the underlying sediments. Also, they are marked by a considerable content of terrestrial plant remains, a lower content of planktonic diatoms, and higher contents of benthic and ancient diatoms. These data indicate that the layer under study formed as a result of the 1912 earthquake, with a considerable contribution from the littoral and shallow-water zones of Lake Baikal.     

A review of water column processes influencing hypoxia in the northern Gulf of Mexico

In this review, we use data from field measurements of biogeochemical processes and cycles in the Mississippi River plume and in other shelf regions of the northern Gulf of Mexico to determine plume contributions to coastal hypoxia. We briefly review pertinent findings from these process studies, review recent mechanistic models that synthesize these processes to address hypoxia-related issues, and reinterpret current understanding in the context of these mechanistic models. Some of our conclusions are that both nitrogen and phosphorus are sometimes limiting to phytoplankton growth; respiration is the main fate of fixed carbon in the plume, implying that recycling is the main fate of nitrogen; decreasing the river nitrate loading results in less than a 1:1 decrease in organic matter sinking from the plume; and sedimenting organic matter from the Mississippi River plume can only fuel about 23% of observed coastal hypoxia, suggesting significant contributions from the Atchafalaya River and, possibly, coastal wetlands. We also identify gaps in our knowledge about controls on hypoxia, and indicate that some reinterpretation of our basic assumptions about this system is required. There are clear needs for improved information on the sources, rates, and locations of organic matter sedimentation; for further investigation of internal biogeochemical processes and cycling; for improved understanding of the rates of oxygen diffusion across the pycnocline; for identification and quantification of other sources of organic matter fueling hypoxia or other mechanisms by which Mississippi River derived organic matter fuels hypoxia; and for the development of a fully coupled physical-biogeochemical model.     

湖泊沉积生物硅的测定与应用:以湖光岩玛珥湖为例

在国外实验方法基础上,初步建立了湖泊沉积生物硅实验室测定方法,硅胶模拟实验表明,该方法准确可靠,沉积样品重复测试显示测量平均偏差小。利用此方法,首次分析了我国雷州半岛湖光岩玛珥湖Ｂ孔部分岩芯生物硅含量,结果显示,生物硅敏感地记录了末次冰消期古季风气候的变化,揭示了快速变化的ＢΦｌｌｉｎｇ－ＡｌｌｅｒΦｄ－Ｙｏｕｎｇｅｒ Ｄｒｙａｓ气候事件,表明了低纬度湖泊沉积生物硅也是一个理想的古气候替代指标。