Effects of naphthalene and phenanthrene on visual and prey capture endpoints during early stages of the dourado Salminus brasiliensis

Naphthalene (NAP) and phenanthrene (PHE) effects on Salminus brasiliensis, a carnivorous freshwater fish, were investigated using behavioral tests. Larval stages of S. brasiliensis were exposed to water concentrations of 0, 0.04 mg/l, 0.20mg/l and 0.50mg/l for naphthalene and 0, 0.01 mg/l, 0.05 mg/l and 0.1mg/l for phenanthrene during two developmental phases. The prey fish Prochilodus lineatus were not exposed. Visual acuity was measured at the end of phase 2 in individual S. brasiliensis, which were also tested at the end of each phase for number of attacks on prey, number of prey captured, prey capture efficiency, and distance swam. Vision was impaired by PHE exposure, as acuity angles increased in exposed fish. At Stage I 2.3+/-1.2 prey were captured with 46% efficiency in controls compared to 0.4+/-0.3 prey captured with 13.4% efficiency in fish exposed to 0.05 mg PHEl(-1), the LOEL for both endpoints. At Stage II 4.0+/-1.1 preys were captured in controls compared to 2.5+/-0.9 preys captured in fish exposed to 0.01 mg PHEl(-1), the LOEL. Stage II control fish captured prey with 70% efficiency compared to 30% efficiency at Stage II fish exposed to 0.05 mg PHEl(-1), the LOEL. Distance swam was not affected by either NAP or PHE exposure. The exposure of larval stages of S. brasiliensis to realistic water concentrations of PHE impairs foraging skills and could affect recruitment of the species.     

Underwater measurements of carbon dioxide evolution in marine plant communities: A new method

We developed a new methodology to determine CO₂ fluxes in intertidal and shallow subtidal plant communities, namely seagrasses, both when the plants are submerged and when they are air-exposed. The apparatus comprises closed incubation chambers and a gas exchange column, designed to remove carbon dioxide from the water. Different types of incubation chambers were designed and built to adapt the system to distinct environments and incubation requirements. The methodology was tested under a comprehensive range of situations and its advantages and limitations are discussed. Overall, the method provides precise measurements of community carbon dioxide fluxes, through a fast and non-intrusive process, allowing repeatable in situ measurements of carbon uptake both in submerged and air-exposed conditions. As the experimental apparatus is identical, directly comparable measurements of air-exposed and submerged community production may be obtained, allowing sound estimates of daily carbon budgets of intertidal and shallow subtidal communities.     

Use of different intertidal habitats by faunal communities in a temperate coastal lagoon

The faunal communities of four intertidal habitats namely sand, mud, seagrass (Zostera noltii) and seagrass patches (mixSM) of a temperate coastal lagoon, Ria Formosa (southern Portugal), were sampled. A total of 47 species were taken in 428 bottomless drop sampler samples, with the highest number of species and the more commonly occurring species belonging to the Mollusca phylum. The dominance of these gastropod species underlines the importance of the grazing food chain in these habitats. Bittium reticulatum was the most abundant species, being especially abundant in the seagrass habitat. The most frequent and highest biomass species in the community was Carcinus maenas, a predator that makes use of the available resources and that is adapted to the highly variable intertidal environment. Pomatoschistus microps was the most abundant fish species, with highest densities in the mud habitat, which demonstrates an ability to occupy a low depth area. The seagrass habitat had the highest diversity, abundance and biomass, followed by the mixSM habitat and was different from all the others. Assemblages were highly influenced by the presence of vegetation, providing forage and refuge from predation. A well defined summer group was identified in all habitats. These results highlight the importance of seagrass beds and the idea that their decrease implies the decrease of lagoon production through the impoverishment of the trophic structure of the lagoon.     

“三联式”成矿预测新进展

随着信息技术的发展 ,矿产勘查已步入数字化、定量化研究的新阶段。“三联式”成矿预测以地质异常分析为基础 ,以成矿多样性分析与矿床谱系研究为指导 ,将地质异常、成矿多样性及矿床谱系 3方面定量化研究紧密结合形成矿产预测及定量评价的切入点 ,是实现“数字找矿”的创新探索。文中对“三联式”成矿预测的基本理论进行了论述 ,结合在固体矿产和油气资源预测评价中的最新研究成果 ,重点论述了“三联式”成矿预测中的地质异常动态演化解析思路和“5P”靶区逐步逼近法。研究认为 :不同时期地质异常各自包含的矿产类型、组合特征与资源潜力等均有明显差异 ,应用地质异常动态演化的解析思路与方法 ,有效提取与相应成矿事件密切相关的致矿地质异常 ,是提高预测成果科学预见性的关键。并且 ,随着“三联式”成矿预测研究的不断深入 ,找矿信息由少到多 ,找矿范围由大到小 ,靶区级别由低到高 ,找矿成功概率逐步增大 ,勘探风险逐步降低。“5P”靶区圈定 ,从 1P到 5P依次研究目标内涵增大、外延减小、预测对象 (矿产种类及成因类型 )渐趋明确。     

Chemical availability of arsenic and heavy metals in sediments from abandoned cinnabar mine tailings

The understanding of the solid-phase speciation of arsenic in soils and sediments is important in the evaluations of its potential mobility and availability in the environment. The spoil heaps of abandoned mercury mines contain waste materials with high arsenic and heavy metals concentrations. The weathering of these tailings can cause their mobilization to the surroundings. In this work, the mobility and availability of arsenic and some heavy metals were evaluated in sediments from two heavily polluted mercury mining districts in Asturias (NW Spain). For this purpose, a slightly modified version of the Bureau Community of Reference sequential extraction scheme was applied to sediments. The total contents in the operationally defined fractions were analysed by inductively coupled plasma-atomic emission spectrometry. Extremely high total arsenic concentrations were found in all sediments ranging from 4,000 to 24,800 mg kg^?1. High easily mobilizable arsenic contents were found in the first mining area, related to the solubilization of Ca-bearing phases, supported by extracts analyses, X-ray diffraction results and the positive correlation found among the As and Ca fractionations. Ni and Zn were the most mobile among heavy metals, being Cr the least mobile, suggesting an anthropogenic origin due to the metallurgical processes, transport or dispersion generated from neighbour spoil heaps. In the second mining area, the bulk of As was concentrated in the residual phase, as well as Cr, Cu, Fe, Pb, Ti, indicating a mineralogical origin and the low availability of these elements. The strong correlations established between As and Fe and Ti distributions support the hypothesis that As is mainly associated to structural mineral phases in these sediments.     

Climate change scenarios of heat waves in Central Europe and their uncertainties

The study examines climate change scenarios of Central European heat waves with a focus on related uncertainties in a large ensemble of regional climate model (RCM) simulations from the EURO-CORDEX and ENSEMBLES projects. Historical runs (1970–1999) driven by global climate models (GCMs) are evaluated against the E-OBS gridded data set in the first step. Although the RCMs are found to reproduce the frequency of heat waves quite well, those RCMs with the coarser grid (25 and 50 km) considerably overestimate the frequency of severe heat waves. This deficiency is improved in higher-resolution (12.5 km) EURO-CORDEX RCMs. In the near future (2020–2049), heat waves are projected to be nearly twice as frequent in comparison to the modelled historical period, and the increase is even larger for severe heat waves. Uncertainty originates mainly from the selection of RCMs and GCMs because the increase is similar for all concentration scenarios. For the late twenty-first century (2070–2099), a substantial increase in heat wave frequencies is projected, the magnitude of which depends mainly upon concentration scenario. Three to four heat waves per summer are projected in this period (compared to less than one in the recent climate), and severe heat waves are likely to become a regular phenomenon. This increment is primarily driven by a positive shift of temperature distribution, but changes in its scale and enhanced temporal autocorrelation of temperature also contribute to the projected increase in heat wave frequencies.     

A Clinopyroxene-Orthopyroxene-Plagioclase Symplectite Formed by Garnet Breakdown in Granulite Facies, Guaxupé, Minas Gerais, Brazil

In mafic granulites, garnet can form by reactions such as Opx + Pl = Cpx + Grt + Qtz; Opx + Pl = Grt + Qtz. As a result of isothermal decompression (ITD), garnet can then break down to a characteristic orthopyroxene-plagioclase symplectite. Mafic, iron-rich garnet-pyroxene granulite from the Guaxupé Massif has symplectite that formed by near-isothermal decompression, as a consequence of uplift of the granulite facies terrane. This symplectite was found to consist of vermicular clinopyroxene-orthopyroxene-plagioclase, with clinopyroxene clearly growing from the garnet that is breaking down, modal amounts of clinopyroxene being less than orthopyroxene. Electron probe analyses show clear differences between core (Cpx₁), rim, and symplectite clinopyroxene (Cpx₂). Considering also the presence of magnetite in the symplectite texture, garnet breakdown is thought to be better represented by a reaction such as Cpx₁ + Grt + O₂ = Cpx₂ + Opx + Pl +Mt + Qtz.     

中国西部环境演变及其影响研究

文章综述了气候与中国西部环境演变过程及其对社会经济的影响 ,特别分析了人类活动和全球变暖条件下的演变特征。以政府间气候变化专门委员会 (IPCC) )的研究方法 ,采用全球大气海洋耦合模式和区域气候模式 ,预测了 2 0 10年、2 0 30年和 2 0 5 0年中国西部地区未来气候生态环境的可能变化趋势即情景。对西部地区生态与经济的脆弱性问题也作了分析 ,最后提出了在西部大开发中实施生态环境保护与可持续发展双赢战略的思想。     

The impact of El Ni?o on South American summer climate during different phases of the Pacific Decadal Oscillation

In austral summer, the observed El Ni?o (EN) events during warm Pacific Decadal Oscillation (PDO) phases (PDO(+)) exhibited large anomalous upper level wave patterns in response to larger Sea Surface Temperature (SST) anomalies in the Equatorial Pacific and Atlantic Oceans compared with SST anomalies in EN events during cold PDO phases (PDO(?)). The precipitation anomalies in PDO(+) EN are increased over Southeastern South America (SESA) associated with the intensification of the moisture flux convergence in this region. The PDO(?) EN events exhibit positive precipitation anomalies only over southern SESA, while negative anomalies were observed in the north. Downward motion and anomalous divergence over central eastern Brazil may have contributed to the weakening of the northwesterly moisture flux convergence associated with the South American Low Level Jet (SALLJ) over the subtropics. The extratropical cyclones showed higher frequency and lower central pressures in southern Brazil, Uruguay, northeastern Argentina, and Southwest Atlantic Ocean during the PDO(+) EN events compared with the PDO(?) EN events. Such increase in the frequency and intensity of cyclogenesis cases seems to be in accordance with the anomalous moisture flux convergence over the SESA and associated reduction in the Sea Level Pressure observed during PDO(+) EN events. In order to investigate the impact of a canonical El Ni?o event over South America under different PDO phases, two numerical experiments were done with an Atmospheric General Circulation Model. Global SST and ice sea fields average over years characterized by (a) PDO(+) and (b) PDO(?) were considered as climatologically fields, and a composite of anomalies of SST of all El Ni?o events observed in 1950?C1999 was added in the region 20oS?C20oN;120oW?C175oW of both ??climatologies.?? The differences in experiments suggest that a canonical EN may produce significant different anomalous atmospheric patterns associated with distinct PDO climatologies. The more significant differences are simulated over extreme northern and eastern Brazil. Additional numerical experiments isolating the observed variability of SST over several oceanic basins during different PDO phases will be conducted to study their particular role on the South American climate.     

The surface radiation budget over South America in a set of regional climate models from the CLARIS-LPB project

The performance of seven regional climate models in simulating the radiation and heat fluxes at the surface over South America (SA) is evaluated. Sources of uncertainty and errors are identified. All simulations have been performed in the context of the CLARIS-LPB Project for the period 1990–2008 and are compared with the GEWEX-SRB, CRU, and GLDAS2 dataset and NCEP-NOAA reanalysis. Results showed that most of the models overestimate the net surface short-wave radiation over tropical SA and La Plata Basin and underestimate it over oceanic regions. Errors in the short-wave radiation are mainly associated with uncertainties in the representation of surface albedo and cloud fraction. For the net surface long-wave radiation, model biases are diverse. However, the ensemble mean showed a good agreement with the GEWEX-SRB dataset due to the compensation of individual model biases. Errors in the net surface long-wave radiation can be explained, in a large proportion, by errors in cloud fraction. For some particular models, errors in temperature also contribute to errors in the net long-wave radiation. Analysis of the annual cycle of each component of the energy budget indicates that the RCMs reproduce generally well the main characteristics of the short- and long-wave radiations in terms of timing and amplitude. However, a large spread among models over tropical SA is apparent. The annual cycle of the sensible heat flux showed a strong overestimation in comparison with the reanalysis and GLDAS2 dataset. For the latent heat flux, strong differences between the reanalysis and GLDAS2 are calculated particularly over tropical SA.