Dissolved inorganic carbon (DIC) and its carbon isotopic composition in sediment pore waters from the Shenhu area,northern South China Sea

The Shenhu area is one of the most favorable places for the occurrence of gas hydrates in the northern continental slope of the South China Sea. Pore water samples were collected in two piston cores (SH-A and SH-B) from this area, and the concentrations of sulfate and dissolved inorganic carbon (DIC) and its carbon isotopic composition were measured. The data revealed large DIC variations and very negative δ ¹³C-DIC values. Two reaction zones, 0–3 mbsf and below 3 mbsf, are identified in the sediment system. At site SH-A, the upper zone (0–3 mbsf) shows relatively constant sulfate and DIC concentrations and δ ¹³C-DIC values, possibly due to bioturbation and fluid advection. The lower zone (below 3 mbsf) displays good linear gradients for sulfate and DIC concentrations, and δ ¹³C-DIC values. At site SH-B, both zones show linear gradients, but the decreasing gradients for δ ¹³C-DIC and SO₄ ²⁻ in the lower zone below 3 mbsf are greater than those from the upper zone, 0–3 mbsf. The calculated sulfate-methane interface (SMI) depths of the two cores are 10.0 m and 11.1 m, respectively. The depth profiles of both DIC and δ ¹³C-DIC showed similar characteristics as those in other gas hydrate locations in the world oceans, such as the Blake Ridge. Overall, our results indicate an anaerobic methane oxidation (AMO) process in the sediments with large methane flux from depth in the studied area, which might be linked to the formation of gas hydrates in this area.     

<Superscript>234</Superscript>Th/<Superscript>238</Superscript>U disequilibrium and particulate organic carbon export in the northern South China Sea

We utilized ²³⁴Th, a naturally occurring radionuclide, to quantify the particulate organic carbon (POC) export rates in the northern South China Sea (SCS) based on data collected in July 2000 (summer), May 2001 (spring) and November 2002 (autumn). Th-234 deficit was enhanced with depth in the euphotic zone, reaching a subsurface maximum at the Chl-a maximum in most cases, as commonly observed in many oceanic regimes. Th-234 was in general in equilibrium with ²³⁸U at a depth of ∼100 m, the bottom of the euphotic zone. In this study the ²³⁴Th deficit appeared to be less significant in November than in July and May. A surface excess of ²³⁴Th relative to ²³⁸U was found in the summer over the shelf of the northern SCS, most likely due to the accumulation of suspended particles entrapped by a salinity front. Comparison of the ²³⁴Th fluxes from the upper 10 m water column between 2-D and traditional 1-D models revealed agreement within the errors of estimation, suggesting the applicability of the 1-D model to this particular shelf region. 1-D model-based ²³⁴Th fluxes were converted to POC export rates using the ratios of bottle POC to ²³⁴Th. The values ranged from 5.3 to 26.6 mmol C m⁻²d⁻¹ and were slightly higher than those in the southern SCS and other oligotrophic areas. POC export overall showed larger values in spring and summer than in autumn, the seasonality of which was, however, not significant. The highest POC export rate (26.6 mmol C m⁻²d⁻¹) appeared at the shelf break in spring (May), when Chl-a increased and the community structure changed from pico-phytoplankton (<2 μm) dominated to nano-phytoplankton (2–20 μm) and micro-phytoplankton (20–200 μm) dominated.     

Geochemistry of pore waters from the Xisha Trough, northern South China Sea and their implications for gas hydrates

This paper reports all available geochemical data on sediments and pore waters from the Xisha Trough on the northern continental margin of the South China Sea. The methane concentrations in marine sediments display a downhole increasing trend and their carbon isotopic compositions (δ ¹³C = −25 to −51‰) indicate a thermogenic origin. Pore water Cl⁻ concentrations show a range from 537 to 730 mM, and the high Cl⁻ samples also have higher concentrations of Br⁻, Na⁺, K⁺, and Mg²⁺, implying mixing between normal seawater and brine in the basin. The SO₄ ²⁻ concentrations of pore waters vary from 19.9 to 36.8 mM, and show a downhole decreasing trend. Calculated SMI (sulfate-methane interfaces) depths and sulfate gradients are between 21 and 47 mbsf, and between −0.7 and −1.7 mM/m, respectively, which are similar to values in gas hydrate locations worldwide and suggest a high methane flux in the basin. Overall, the geochemical data, together with geological and geophysical evidence, such as the high sedimentation rates, high organic carbon contents, thick sediment piles, salt and mud diapirs, active faulting, abundant thermogenic gases, and occurrence of huge bottom simulating reflector (BSR), are suggestive of a favorable condition for occurrence of gas hydrates in this region.     

原位杂交技术在斜带石斑鱼神经坏死病毒检测中的应用

根据斜带石斑鱼（Epinephelus coioids）神经坏死病毒（orang-spotted nervous necrosis virus,0GNNV）的主衣壳蛋白（major capsid protein,MCP）基因的保守序列,设计一对引物,从感染0GNNV的斜带石斑鱼组织匀浆液提取RNA为模板进行RT-PCR扩增,得到426bp的cDNA片断。用得到的RT-PCR产物加上地高辛（DIG）标记作为核酸探针。通过注射病毒提取液人工感染一组斜带石斑鱼,解剖感染病毒的斜带石斑鱼,从中分离出脑和眼睛,运用原位杂交技术检测组织中的OGNNV。实验表明,原位杂交具有较高的灵敏性和特异性,可以用原位杂交的办法来检测养殖的石斑鱼是否有携带该病毒,达到监控和预防神经坏死病爆发的目的。本实验还采用了H＆E染色方法检测了感染NNV的石斑鱼脑部和眼部组织,观察细胞内的坏死部分。与原位杂交做对比,提高了检测的可靠性和准确性。本实验建立的石斑鱼神经坏死病毒的ISH检测方法有着较高的特异性和敏感性,易于操作,有助于石斑鱼神经坏死病毒的组织定位、发病机理的研究。     

Outburst risk of barrier lakes in Sichuan,China

34 barrier lakes induced by earthquake have been formed by wedged debris on the river channels after a massive earthquake happening on May 12 in Sichuan, China. Among them, the Tangjiashan Barrier Lake is the largest one. It faces very urgent risk of dam breaking when water level reaches the top and begins overflow in case of storm rainfalls and continually aftershocks, threatening already devastated cities and villages with about 1.5 million people downstream. The outburst of a similar barrier lake occurred in the Minjiang River in 1933, causing a catastrophic flood. Risk analysis indicates that not all barrier lakes are highly dangerous. Only those lakes with very high dams and water to be filled up in short period need to be dealt with immediately.     

栖霞市马家窑金矿床成矿流体地球化学特征

马家窑金矿床是胶东地区比较典型的石英脉型金矿床代表,属中低温热液矿床,成矿流体盐度较低,气相成分以H2O,CO2为主,其次是Na^＋,Ca^＋和Cl^-,K^＋和F^-较贫,流体的成分与大气降水热液相类似。成矿流体的H,O同位素值则反映大气降水在不同温度和不同水／岩值条件下与栖霞超单元回龙夼单元交换后的分布特征,认为马家窑金矿床的成矿热液属大气降水成因。     

鲁西南隐伏区单县煤田曹县煤田的发现及其意义

继巨野煤田之后,近期在鲁西南隐伏区又相继发现了单县煤田和曹县煤田。它指示着隐伏区赋煤规律及找煤方向是：掀斜断凸的北缘,大型潜凸的周边,凹陷中的凸起,凸起中的凹陷。表明山东省深部找煤潜力巨大,前景广阔。应系统开展曹县一鄄城、阳谷一茌平、黄河北、章丘煤田深部、淄博煤田外围、单县一嘉祥6个含煤预测区的深部找矿工作。     

对影响招远市黄金矿山地质环境评价的几点认识

招远市黄金资源蕴藏丰富,开采历史悠久,素有“金城天府”之称,建国以来,累计向国家交售黄金近200t,是全国第一产金大市（县）。其矿山地质环境问题不同于一般的县市,通过对其矿山地质环境特点的分析,认为招远市金矿区矿山地质环境影响评价的重点为采空塌陷,地裂缝,渣石流等地质灾害及水环境等。     

山东五莲七宝山窑头隐爆角砾岩筒矿化特征及意义

五莲七宝山地区岩浆活动频繁,具有多期次岩浆活动。环状断裂与辐射状断裂发育,形成七宝山复式火山机构。隐爆角砾岩是火山活动的产物,具有良好的成矿机制和控矿作用,窑头隐爆角砾岩筒成矿时代为燕山晚期。对窑头隐爆角砾岩筒的产状、分布、规模、围岩蚀变等地质特征进行了分析,推断窑头铜（金）矿为隐爆角砾岩型低温热液小型矿床。     

济南张夏组灰岩岩溶地下水供水潜力探讨

济南南部广布巨厚张夏组灰岩,其中赋存优质丰富的岩溶地下水。出露众多泉水,其流量为800～8000m3/d。该文通过简述济南地区张夏组灰岩岩溶地下水的赋存条件与水文地质特征,概略计算与评价其资源量,论证开发利用这一新水源的可行性,以期为济南供水与保泉开辟新途径。