新疆白杨河铍铀矿床萤石Sm-Nd和沥青铀矿U-Pb年代学及其地质意义

白杨河矿床是我国类型独特的一个特大型铍、铀多金属矿床,铍矿物主要确定为羟硅铍石,铀矿物主要发现沥青铀矿和次生的硅钙铀矿以及少量的铌铀矿,伴生矿物主要是萤石。为恢复铀和铍的成矿过程,划分成矿阶段,本次工作通过系统采集钻孔中的萤石样品,进行了Sm-Nd同位素测年研究,获得了三组等时线年龄,分别为291±16Ma、265±33Ma和207±37Ma,代表了成矿前、成矿期和成矿后萤石的形成;采集中心工地、新西工地和九号工地平巷内的沥青铀矿样品,进行了UPb同位素测年研究,获得了~(206)Pb/~(238)U表观年龄237.8±3.3Ma、224±3.1Ma、197.8±2.8Ma、97.8±1.4Ma和30.0±0.4Ma,利用U-Pb表观年龄将铀矿化划分为四个阶段:中三叠世、晚三叠-早侏罗世、晚白垩世和古近纪中期。因此,白杨河矿床具有铍早铀晚的成矿特点,铀成矿经历了四个阶段。     

Enzymatic activity in the rhizosphere of Spartina maritima: potential contribution for phytoremediation of metals

Extracellular enzymatic activity (EEA) of five enzymes (peroxidase, phenol oxidase, beta-glucosidase, beta-N-acetylglucosaminidase and acid phosphatase) was analysed in sediments colonised by Spartina maritima in two salt marshes (Rosário and Pancas) of the Tagus estuary (Portugal) with different characteristics such as sediment parameters and metal contaminant levels. Our aim was a better understanding of the influence of the halophyte on microbial activity in the rhizosphere under different site conditions, and its potential consequences for metal cycling and phytoremediation in salt marshes. Acid phosphatase and beta-N-acetylglucosaminidase presented significantly higher EEA in Rosário than in Pancas, whereas the opposite occurred for peroxidase. This was mainly attributed to differences in organic matter between the two sites. A positive correlation between root biomass and EEA of hydrolases (beta-glucosidase, beta-N-acetylglucosaminidase and acid phosphatase) was found, indicating a possible influence of the halophyte in sediment microbial function. This would potentially affect metal cycling in the rhizosphere through microbial reactions.     

Biochemical alterations in juvenile carp (Cyprinus carpio) exposed to zinc: glutathione reductase as a target

The aim of this study was to investigate biochemical changes in juvenile carp (Cyprinus carpio) exposed to zinc chloride (10, 30 and 100 microM) for a period of 48 h. Zinc exposure caused a concentration-dependent reduction in glutathione reductase (GR) activity in gills, liver and brain. Gill glutathione S-transferase (GST) was reduced when animals were exposed to the highest concentration of 100 microM zinc. The phosphorylation of p38(MAPK) increased in the brain of fish exposed to zinc 100 microM, while phosphorylation of the extracellular signal-regulated protein kinase 1/2 (ERK1/2) and c-Jun N-terminal protein kinase 1/2 (JNK1/2) remained unchanged. Expression of proteins HSP60 and HSP70 were not affected by zinc exposure. Considering the significant concentration-dependent inhibition of GR in all tissues analyzed, this enzyme could be a potential biomarker of exposure to zinc, which has to be confirmed.     

“Trends” and variations of global oceanic evaporation data sets from remote sensing

The variability in global oceanic evaporation data sets was examined for the period 1988-2000. These data sets are satellite estimates based on bulk aerodynamic formulations and include the NASA/Goddard Space Flight Center Satellite-based Surface Turbulent Flux version 2 （ GSSTF2）, the Japanese-ocean flux using remote sensing observations （J-OFURO）, and the Hamburg Ocean-Atmosphere Parameters and Fluxes from Satellite version 2 （HOAPS2）. The National Center for Environmental Prediction （NCEP） reanalysis is also included for comparison. An increase in global average surface latent heat flux （SLHF） can be observed in all the data sets. Empirical mode decomposition （EMD） shows long-term increases that started around 1990 for all remote sensing data sets. The effect of Mt. Pinatubo eruption in 1991 is clearly evident in HOAPS2 but is independent of the longterm increase. Linear regression analyses show increases of 9.4%, 13.0%, 7. 3%, and 3.9% for GSSTF2, J-OFURO, HOAPS2 and NCEP, for the periods of the data sets. Empirical orthogonal function （EOF） analyses show that the pattern of the first EOF of all data sets is consistent with a decadal variation associated with the enhancement of the tropical Hadley circulation, which is supported by other satellite observations. The second EOF of all four data sets is an ENSO mode, and the correlations between their time series and an SO1 are 0.74, 0.71,0.59, and 0.61 for GSSTF2, J-OFURO, HOAPS2, and NCEP in that order. When the Hadley modes are removed from the remote sensing data, the residue global increases are reduced to 2.2% , 7. 3%, and 〈 1% for GSSTF2, J-OFURO and HOAPS, respectively. If the ENSO mode is used as a calibration standard for the data sets, the Hadley mode is at least comparable to, if not larger than, the ENSO mode during our study period.     

卡里马塔海峡水体交换的季节变化

Four trawl-resistant bottom mounts, with acoustic Doppler current profilers(ADCPs) embedded, were deployed in the Karimata Strait from November 2008 to June 2015 as part of the South China Sea-Indonesian Seas Transport/Exchange and Impact on Seasonal Fish Migration(SITE) Program, to estimate the volume and property transport between the South China Sea and Indonesian seas via the strait. The observed current data reveal that the volume transport through the Karimata Strait exhibits significant seasonal variation. The winteraveraged(from December to February) transport is –1.99 Sv(1 Sv=1×10~6 m~3/s), while in the boreal summer(from June to August), the average transport is 0.69 Sv. Moreover, the average transport from January 2009 to December2014 is –0.74 Sv(the positive/negative value indicates northward/southward transport). May and September are the transition period. In May, the currents in the Karimata Strait turn northward, consistent with the local monsoon. In September, the southeasterly trade wind is still present over the strait, driving surface water northward, whereas the bottom flow reverses direction, possibly because of the pressure gradient across the strait from north to south.     

Differentiated payments for environmental services schemes: Amethodology proposal

Payment schemes for environmental services face serious budget constraints in Mexico. Payments are equally distributed among forest owners, and the governmental agencies that make payments to beneficiaries do not evaluate the amount of environmental services produced by forested areas. This lack of evaluation could lead to economic and environmental deficiencies that restrict the possible benefits of such programmes. In general, these programmes do not achieve their conservation objectives, and local beneficiaries are not involved in the design or application of these programmes. Similarly, the Payments for Hydrological Environmental Services (PHES) programme of the State of Mexico, Mexico, makes equal payments to beneficiaries of forested areas considering tree density. The objective of the present work was to create a methodology for determining differentiated payments schemes for hydrological environmental services, prioritising areas that contribute the most to groundwater recharge and promote the participation of society. In the Nevado de Toluca Natural Protected Area, the environmental criteria of forest type, tree density and aquifer overexploitation as well as social participation were considered in a multi-criteria analysis implemented in a Geographic Information System. A methodology was developed to determine differentiated payments based on specific forest characteristics that influence the potential capacity of forests to recharge groundwater reserves in addition to the level of social participation. In particular, social participation is key as it could ensure the viability of PHES programmes as conservation alternatives in forested areas with high groundwater recharge potential.     

Challenges in the Detection and Attribution of Northern Hemisphere Surface Temperature Trends Since 1850

Since 2007, the Intergovernmental Panel on Climate Change(IPCC) has heavily relied on the comparison between global climate model hindcasts and global surface temperature(ST) estimates for concluding that post-1950s global warming is mostly human-caused. In Connolly et al., we cautioned that this approach to the detection and attribution of climate change was highly dependent on the choice of Total Solar Irradiance(TSI) and ST data sets.We compiled 16 TSI and five ST data sets and found by alter...     

加里福尼亚南部岸外泥火山的甲烷成因方解石、13C亏损的双壳类贝壳以及气水合物

沿大陆边缘的气体和流体通量与构造—沉积过程和(产生冷泉、温泉和甲烷水合物的)物化条件有关(如Obzhirov等,2004)。我们对水合物进行了深入研究,因为它对块体坡移、能源、全球气候突然变化以及全球的碳质量平衡具有潜在的贡献。其中冷泉尤其重要,因为其与大的气体和流体通量、     

Mechanical compression release device in steel bracing system for retrofitting RC frames

1 Introduction Braced steel frames are commonly used to resist seismic loads. Their seismic behavior was extensively studied during the past decades (Bertero et al.., 1989; Roeder, 1989; Jain, 1978). Their design is governed by the buckling behavior of the bracing members (ASCE, 1994,2002; CSA, 1994). To prevent or delay the seismic buckling of compressive members in concentrically braced frames in steel structures, a great number of methods have been proposed. These include the use of sp…