Sr isotopic and elemental characteristics of calcites in the Chinese deserts: Implications for eolian Sr transport and seawater Sr evolution

Calcite content, Sr concentrations, and isotopes of calcites in the Chinese deserts are systematically studied in this paper. Calcite contents, which are calculated according to acid-soluble Ca contents in the deserts, are generally higher in the sandy deserts than in the sandy lands and decrease roughly from northwest to northeast of China. Acid-soluble Sr is well correlated with calcite in the Chinese deserts, implying acid-soluble Sr comes mainly from the calcite dissolution. Sr concentrations in calcites, calculated on the basis of calcite contents and acid-soluble Sr concentrations in the deserts, have an inverse relation to calcite contents, essentially mirroring the degree of Sr substitution for Ca in the calcite development. Desert calcites have regional variations in Sr isotopic ratios. Calcite Sr isotopic ratios depend on geological settings and chemical weathering. The Badain Jaran, and Tengger deserts are probably affected by additional factors such as the remote groundwater cycle or overturning of underlying sand deposits.Only four deserts (Taklimakan, Qaidam, Badain Jaran, and Tengger) appear to be potential sources of eolian deposits in the Chinese Loess Plateau (CLP). Isotopic signatures of calcite Sr and silicate Nd further indicate that the Tengger desert was not an important source for eolian deposits in the CLP. Eolian calcite was probably enriched due to wind sorting from the potential sources to the CLP and suffered weathering–leaching after it accumulated in the CLP. Sr isotopic compositions and Ca/Sr molar ratios of calcites are different between the deserts and the Lingtai profile, due to the integrated effect of wind sorting and weathering–leaching.It is essential to calculate accurately the ⁸⁷Sr/⁸⁶Sr ratio and Sr concentration of eolian calcite entering the oceans according to geochemical data of the Chinese deserts, because of the importance of the Chinese deserts in the global dust cycle. The calculated Sr concentration and ⁸⁷Sr/⁸⁶Sr ratio of eolian calcite entering the North Pacific Ocean, are 11.75 μmol/g and 0.71032, respectively. The calculated values in this study are close to the recommended values by Jacobson [Jacobson A. D. (2004) Has the atmospheric supply of dissolved calcite dust to seawater influenced the evolution of marine ⁸⁷Sr/⁸⁶Sr ratios over the past 2.5 million years? Geochem. Geophys. Geosyst. 5(12), 1–9, Q12002. doi:10.1029/2004GC000750]. Using the same model as that of Jacobson (2004), the effect of Asia dust on the evolution of seawater Sr isotopes is evaluated. (⁸⁷Sr/⁸⁶Sr)_seawater increases by 0.3 × 10⁻⁵ if the lower dust flux of 2.34 × 10⁸ mol Sr/yr is used in the model, suggesting the little effect of Asian dust on the seawater Sr record in the Quaternary. The increase in (⁸⁷Sr/⁸⁶Sr)_seawater is 1.5 × 10⁻⁵ if the higher value of 1.17 × 10⁹ mol Sr/yr is used, as observed in the Quaternary Sr record. These results further support the suggestions of Jacobson (2004).     

Intrusion of the Kuroshio into the South China Sea,in September 2008

Using widespread conductivity–temperature–depth (CTD) data in the Philippine Sea and northern South China Sea near the Luzon Strait together with altimeter data, we identified an intrusion of water from the Kuroshio into the South China Sea (SCS) through the Luzon Strait in September 2008. The Kuroshio water obviously intruded into the SCS from 20 to 21°N, and existed mainly in the upper 300 m. The intrusion water extended as far west as 117°E, then looped around in an anticyclonic eddy and returned to the Philippine Sea further north. The dynamics of the Kuroshio intrusion are discussed using a 1.5-layer nonlinear shallow-water reduced-gravity model. The analysis suggests that the strong cyclonic eddy to the east of the Kuroshio in September 2008 was of benefit to the intrusion event.     

行星运动与厄尔尼诺、东北夏季低温冷害

利用厄尔尼诺与行星运动的联系,对厄尔尼诺进行了分类。发现东北夏季低温冷害的发生与厄尔尼诺的类型有关：负极值型和负正极值型厄尔尼诺的发生年几乎与冷害年一一对应,其他类型的厄尔尼诺则很少甚至不发生冷害。统计表明：三大行星（火、木、土）冲日时日心黄纬的负极值年的次年和木星的正极值的前一年及当年,有利于冷害的发生;土星运行到日心黄经为１９～１２１°时,会导致冷害群的发生。     

Observation system simulation experiments using an ensemble-based method in the northeastern South China Sea

Journal of Oceanology and Limnology - An ensemble-based method for the observation system simulation experiment (OSSE) is employed to design optimal observation stations and assess the present...     

Numerical study on the eddy–mean flow interaction between a cyclonic eddy and Kuroshio

A three-dimensional primitive equations ocean model (POM) is employed to study the momentum and energy balance of a moving cyclonic eddy (CE) during eddy–mean flow interaction. The CE generated by an idealized typhoon forms to the east of the Philippine islands. A momentum balance analysis shows that the dynamics of the CE are generally dominated by the geostrophic current throughout the life cycle of the CE. An energy analysis suggests that the eddy kinetic energy (EKE) and the eddy potential energy (EPE) decay rapidly after generation. The maximum EPE initially appears at the surface of the eddy center and gradually appears in the subsurface layer. The largest baroclinic instability (BCI) initially occurs at the surface. For a CE moving along a trajectory, the conversion from mean potential energy (MPE) to the EPE is positive (negative) in the front (rear) part of the trajectory, and then the eddy transfers its EPE forward along its trajectory by means of the front (rear) part of the eddy obtaining (losing) EPE from (to) the mean flow. During the interaction stage, the northward flowing Kuroshio interacts with the southward flow on the western side of the eddy and the inverse velocity shear between the Kuroshio and the eddy causes the EKE to gradually develop east–west asymmetry. The largest barotropic instability (BTI) is found in the interaction zone. Advection term, pressure work, and friction term play the dominating role in eddy decay in the eddy zone, while BTI only dominates in the interaction zone.     

山东沂水紫苏花岗岩特征-形成时代及成因探讨

通过对山东沂水地区紫苏花岗岩野外地质特征、岩相学及地球化学特征等的研究,认为山东沂水地区紫苏花岗岩为变质表壳岩经深熔作用形成．其主要证据为：（１）紫苏花岗岩与变质表壳岩在空间上密切伴生,二者多为渐变过渡接触关系,且他们的片麻理协调一致;（２）在变质表壳岩中发育大量长英质或花岗质脉体,这些脉体的矿物成分、地球化学特征与紫苏花岗岩一致;（３）紫苏花岗岩与变质表壳岩具有相似的稀土配分型式;（４）紫苏花岗岩亏损大离子亲石元素及生热元素,其原岩应为经历了深变质作用的岩石;（５）紫苏花岗岩中锆石多为圆粒状和椭球状,并发育磨蚀坑,说明其原岩主要为变沉积岩;（６）麻粒岩相变质作用时间与紫苏花岗岩形成时间基本一致．     

Discussion about mechanism of harmful algal blooms breakout

HAB (harmful algal bloom) is a serious marine ecological disaster. Up to now there is no definite conclusion about its mechanism of occurrence.The observation results show that the HAB breakout in the Xiangshan Bay was mainly caused by physical convergence capacity,and the breakout process had no direct relation to eutrophication.As a new idea it is thought that the process of the HAB breakout is mainly a physical convergence or accumulation process in some areas. A hypothesis about dynamic mechanism of the HAB appearing in the area off the Changjiang Estuary is put forward according to hydrology and topography and the past work, and a breakthrough is expected to be made for doing further research.     

塔里木盆地东北部英吉苏凹陷侏罗系沉积-构造背景

英吉苏凹陷位于塔里木盆地东北部,侏罗纪属中亚——中国西北超大型盆地的一部分,是早侏罗世形成的克拉通内盆地。基于钻井、地震剖面、砂岩骨架颗粒分析和地球化学资料,本文提出当时其北界可达库鲁克塔格,物源区主要是南边的古造山带,物源为晋宁期岛弧花岗闪长岩闪长岩及部分下古生界。受燕山运动影响,中侏罗世晚期-晚侏罗世该凹陷闭合隆起,白垩纪时重又沉陷成为塔里木北部坳陷的一部分。     

Application of multi-agent models to urban expansion in medium and small cities: A case study in Fuyang City, Zhejiang Province, China

In this study, three-phase satellite images were used to define rules for the allocation of time and space in construction land resources based on a complex adaptive system and game theory. The decision behavior and rules of government agent, enterprise agent and resident agent in construction land growth were explored. A distinctive and dynamic simulation model of construction land growth was built, which integrated multi-agent, GIS technology and RS data and described the interaction among influencing agents, Taking Fuyang City in the Changjiang River Delta as an example, an assessment process for the remote sensing data in construction land and scenario planning was constructed. Repast and ArcGIS were used as simulation platforms. A simulation of the spatial pattern in land-use planning and the setting of scenario planning were conducted by using the incomplete active game, which was based on different natural, social and economic levels. Through this model, a simulation of urban planning space and decision-making for Fuyang City was created. Relevant non-structured problems arising from urban planning management could be identified, and the process and logic of urban planning spatial decision-making could thus be improved. Cell-by-cell comparison showed that the simulation accuracy was over 72%. This model has great potential for use by government and town planners in decision support and technique support in the policy-making process.     

Vertical structure and evolution of the Luzon Warm Eddy

Eddies are frequently observed in the northeastern South China Sea (SCS). However, there have been few studies on vertical structure and temporal-spatial evolution of these eddies. We analyzed the seasonal Luzon Warm Eddy (LWE) based on Argo float data and the merged data products of satellite altimeters of Topex/Poseidon, Jason-1 and European Research Satellites. The analysis shows that the LWE extends vertically to more than 500 m water depth, with a higher temperature anomaly of 5°C and lower salinity anomaly of 0.5 near the thermocline. The current speeds of the LWE are stronger in its uppermost 200 m, with a maximum speed of 0.6 m/s. Sometimes the LWE incorporates mixed waters from the Kuroshio Current and the SCS, and thus has higher thermohaline characteristics than local marine waters. Time series of eddy kinematic parameters show that the radii and shape of the LWE vary during propagation, and its eddy kinetic energy follows a normal distribution. In addition, we used the empirical orthogonal function (EOF) here to analyze seasonal characteristics of the LWE. The results suggest that the LWE generally forms in July, intensifies in August and September, separates from the coast of Luzon in October and propagates westward, and weakens in December and disappears in February. The LWE’s westward migration is approximately along 19°N latitude from northwest of Luzon to southeast of Hainan, with a mean speed of 6.6 cm/s.