新疆及邻区MS≥6地震与中国大陆地磁日变化相关性分析

<正>1研究背景新疆及周边地区地质构造活跃,强震活动频繁,2008年以来发生多次6.0级及以上地震,其中≥6.5级地震10余次,如：2016年吉尔吉斯坦M_S 6.7、中国新疆阿克陶MS 6.7和呼图壁MS 6.2地震,2017年新疆精河MS 6.6地震,2020年1月19日新疆伽师县M_S 6.4地震(39.83°N,77.21°E),等等。在几百千米范围内,地磁垂直分量日变化相关性较好,一些研究者据此对大震前后的数据变化进行分析,如：林美等(1982)、冯志生等(1998)、     

气候影响下的荒漠下的荒漠化监测

根据揭示沙漠化扩张内在规律的相关气候驱动因子的假说,气候作用影响之下的沙漠化是在具反射率-降水正、负反馈特点的气候系统之中的区域干旱化过程与干旱土壤退化过程相互作用的结果。在辐射调节下的地表下垫面温度占主导的条件下,气候成因的沙漠化是由区域气候系统反馈所形成。正反馈的外部调节因子是降水量的变化和极端降水事件(特别是旱灾)的出现频率,降水量减少以及降水频率的降低直接影响沙漠化的程度。20世纪下半叶,人类因素导致的干旱土地退化作为另外的正反馈调节因子,其重要性正在增加。通常正反馈的扩大趋势会被通过蒸腾而进行的地表温度调节的负反馈所抑制。由正反馈到负反馈的转换是通过地球表面与大气层之间的热量交换的调节所确定的,其中非潜热因子处于增加状态。上述情况在反射率和地表温度同时增加的条件下发生。在超出绿色植物生物量及其NDVI指数阈值的条件下,负反馈向正反馈的转换就会发生。人为作用导致的植被退化加快了向绿色植物生物量阈值逼近的进程,从而引起气候因素驱动的沙漠化扩大。一个主要由气候因素影响的荒漠化区域,在大多数情况下,其绿色生物量均在季节变化和年际变化中达到了阈值。在中度的人为影响的植被退化条件下,这些地域一般都包括部分干旱与半干旱土地。然而有时,人类活动也会导致干旱的半湿润土地退化。本文运用Turan和Sahel地区1982-2001年NDVI指数的监测结果,分析了全球变暖和人为作用导致的土地退化。     

一种在线明渠堰槽流量计准确性方法研究

明渠流量计广泛运用于城市供水、污水处理、企业污水排放以及农业灌溉等领域,一般搭配各种堰槽使用,其中巴歇尔槽以其精度高、测量范围广、水头损失小以及固态杂质不易沉积等优点被广泛使用。但其需要计量工作人员在现场进行校准测量之后进行计算,使得结果准确度相低、且测量过程复杂、人为因素造成误差大。因此有必要对影响巴歇尔槽明渠流量计的计量特性进行研究,本研究分别设计了试验用巴歇尔槽和二次仪表(数据采集系统)以及该数据采集系统对应的数据处理、显示、存储软件,方便进行数据处理和数据分析,从而为现场校准工作提供理论依据,使计量工作人员的校准工作有理可依,使计量工作的结果更准确有效。     

Geochemistry and Petrogenesis of Late Ediacaran Rare-metalAlbite Granites of the Arabian-Nubian Shield

The Abu Dabbab albite granite(ADAG), in the central Eastern Desert of Egypt, hosts the most significant rare metal ore deposit in the northern part of the Neoproterozoic Arabian-Nubian Shield. Here, we report detailed field,petrographic, mineralogical and geochemical investigation of the ADAG, an isolated stock-like granitic body with sharp intrusive contacts against metamorphic country rocks, probably emplaced at about 600 Ma. The fine-grained porphyritic upper unit is a preserved remnant of the shallowly-emplaced apex of the magma chamber, whereas the medium-grained lower unit crystallized at deeper levels under subvolcanic conditions. The peraluminous leucocratic ADAG shares common geochemical characteristics with post-collisional intraplate A-type magmas. In addition to the conspicuous enrichment in Na2 O, the ADAG is remarkable for its anomalous concentrations of Ta, Nb, Li, Hf, Ga, Sn, Zn and heavy rare-earth elements. Nb-Ta minerals in the ADAG are mixed with Fe-Mn oxides, forming black patches that increase in abundance toward of the base of the intrusion. Columbite-tantalite, cassiterite and wolframite are the most important ore minerals.Pronounced negative Eu anomalies(Eu/Eu* = 0.10–0.24) reflect extreme magmatic fractionation and perhaps the effects of late fluid-rock interaction. The ADAG was most likely generated by partial melting of the juvenile middle crust of the ANS as the geotherm was elevated by erosional uplift following lithospheric delamination and it was emplaced at the intersection of lineations of structural weakness. Although formation of the ADAG and its primary enrichment in rare metals are essentially due to magmatic processes, late-stage metasomatism caused limited redistribution of rare metals. Fluid-driven subsolidus modification was limited to the apex of the magma chamber and drove development of greisen, amazonite, and quartz veins along fracture systems.     

新疆塔中油田中古58井寒武系芙蓉统白云岩储层特征

塔里木板块广泛分布的寒武系白云岩储层具重要的油气勘探潜力.塔中油田I号断裂带的中古58井寒武系芙蓉统下丘里塔格群白云岩在区域上有代表性,具有孔隙规模大且储层物性好的优势.储集空间类型包括小型溶洞、溶孔、晶间孔、晶间溶孔及裂缝等,常充填石英、隐晶质硅质、白云石、萤石、黄铁矿、闪锌矿、方解石并呈现明显的充填次序;有效储层包...     

Benthic infaunal communities around two artificial reefs in Mamala Bay, Oahu, Hawaii

Non-fishery use of artificial reefs has been given attention in recent years. The primary concern associated with non-fishery artificial reefs is their effects to the surrounding ecosystems. This study examined the infaunal communities around two non-fishery artificial reefs (the sunken vessels YO257 and Sea Tiger) in Mamala Bay, Hawaii. Infaunal community structures at these artificial reefs were relatively similar to one at a nearly natural patch reef. A large amount of basalt gravel around YO257 associated with its deployment operation possibly had an effect on the surrounding community by increasing pore space. Polychaete assemblages were compared with existing data throughout the bay, and this revealed that the variation in sediment grain sizes and depths seemed to play some role in structuring the polychaete communities. Nevertheless, the infaunal communities around the artificial reefs were typical and within the range of natural variation in Mamala Bay, supporting their beneficial uses in ecotourism.     

The amphipod Talitrus saltator as a bioindicator of human trampling on sandy beaches

The present paper assesses the use of the supralittoral amphipod Talitrus saltator as a bioindicator of the effects of human trampling on the supralittoral sandy band. Samplings in delimited areas were carried out at sites subjected to different human impact. The results showed a strong negative correlation between the number of swimmers and the sandhopper population density, while there was no clear relationship between sandhopper abundance and the other factors considered: granulometry, compactness and organic carbon content of the sand, and trace metal contents in the sand and sandhoppers. A field test of trampling conducted in a confined space showed its direct negative effect on sandhopper survival. However, trace metal analysis confirmed the ability of T. saltator to bioaccumulate some elements (Hg, Zn, Cu, Cd). Our study demonstrates that T. saltator is a good bioindicator of human impact in the supralittoral zone of sandy shores.     

Domoic acid excretion in dungeness crabs, razor clams and mussels

Domoic acid (DA) is a neurotoxic amino acid produced by several marine algal species of the Pseudo-nitzschia (PN) genus. We studied the elimination of DA from hemolymph after intravascular (IV) injection in razor clams (Siliqua patula), mussels (Mytilus edulis) and Dungeness crabs (Cancer magister). Crabs were also injected with two other organic acids, dichloroacetic acid (DCAA) and kainic acid (KA). For IV dosing, hemolymph was repetitively sampled and DA concentrations measured by HPLC-UV. Toxicokinetic analysis of DA in crabs suggested most of the injected dose remained within hemolymph compartment with little extravascular distribution. This observation is in sharp contrast to results obtained from clams and mussels which exhibited similarly large apparent volumes of distribution despite large differences in overall clearance. These findings suggest fundamentally different storage and elimination processes are occurring for DA between bivalves and crabs.     

Diagnosis of trace metal contamination in sediments: the example of Ensenada and El Sauzal, two harbors in Baja California, Mexico

Total metal concentrations in sediments from within Ensenada and El Sauzal Harbors are generally higher than at the mouths. Grain-size analyses suggested that this enrichment could be due to the presence of fine-grained sediments in the inner part of the harbors rather than to anthropogenic perturbations. The (Me/Al)(sample) ratios for Pb, Co, Ni and Fe were significantly higher for Ensenada Harbor relative to El Sauzal Harbor, whereas the ratios for Cd, Mn, Zn and Cu were statistically equivalent for both harbors. Calculated enrichment factors [EF(Me)=(Me/Al)(sample)/(Me/Al)(shale)] indicated that the metals showing slight enrichment were those associated with anthropogenic contamination (Pb, Zn), or probably related to primary productivity in the water column (Cd, Co). The levels of most of the metals were not greatly enriched, a consideration that is of the utmost importance when contamination issues are at stake.     

Habitat continuity effects on gradients of fish biomass across marine protected area boundaries

Marine protected areas (MPAs) could be useful as fisheries management tools for the exportation of pelagic eggs, larvae and adult fish. A decreasing gradient of fish biomass across MPAs boundary may indicate export. We determine whether gradients of decreasing biomass of fish assemblage occurred in Tabarca Marine Reserve over two habitats with different continuity across the boundaries, to test if the patchy nature of the marine environment might act as a barrier for the fish export. In general, significant decreasing gradients in total fish biomass and biomass of some species were observed on P. oceanica and rocky substrates, independently of their different continuity through the reserve boundaries. Changes in the multivariate structure of the fish assemblage were correlated with the distance from integral reserve. All of these results support the hypothesis that the exportation of adult fish from Tabarca Marine Reserve occurs, and this process may influence the surrounding fished areas.