Geochemistry of regional background aerosols in the Western Mediterranean

The chemical composition of regional background aerosols, and the time variability and sources in the Western Mediterranean are interpreted in this study. To this end 2002–2007 PM speciation data from an European Supersite for Atmospheric Aerosol Research (Montseny, MSY, located 40 km NNE of Barcelona in NE Spain) were evaluated, with these data being considered representative of regional background aerosols in the Western Mediterranean Basin. The mean PM₁₀, PM_2.5 and PM₁ levels at MSY during 2002–2007 were 16, 14 and 11 µg/m³, respectively. After compiling data on regional background PM speciation from Europe to compare our data, it is evidenced that the Western Mediterranean aerosol is characterised by higher concentrations of crustal material but lower levels of OM + EC and ammonium nitrate than at central European sites. Relatively high PM_2.5 concentrations due to the transport of anthropogenic aerosols (mostly carbonaceous and sulphate) from populated coastal areas were recorded, especially during winter anticyclonic episodes and summer midday PM highs (the latter associated with the transport of the breeze and the expansion of the mixing layer). Source apportionment analyses indicated that the major contributors to PM_2.5 and PM₁₀ were secondary sulphate, secondary nitrate and crustal material, whereas the higher load of the anthropogenic component in PM_2.5 reflects the influence of regional (traffic and industrial) emissions. Levels of mineral, sulphate, sea spray and carbonaceous aerosols were higher in summer, whereas nitrate levels and Cl/Na were higher in winter. A considerably high OC/EC ratio (14 in summer, 10 in winter) was detected, which could be due to a combination of high biogenic emissions of secondary organic aerosol, SOA precursors, ozone levels and insolation, and intensive recirculation of aged air masses. Compared with more locally derived crustal geological dusts, African dust intrusions introduce relatively quartz-poor but clay mineral-rich silicate PM, with more kaolinitic clays from central North Africa in summer, and more smectitic clays from NW Africa in spring.     

The XMM Cluster Survey: forecasting cosmological and cluster scaling-relation parameter constraints

We forecast the constraints on the values of  σ₈, Ω_m  and cluster scaling-relation parameters which we expect to obtain from the XMM Cluster Survey (XCS). We assume a flat Λ cold dark matter Universe and perform a Monte Carlo Markov Chain analysis of the evolution of the number density of galaxy clusters that takes into account a detailed simulated selection function. Comparing our current observed number of clusters shows good agreement with predictions. We determine the expected degradation of the constraints as a result of self-calibrating the luminosity–temperature relation (with scatter), including temperature measurement errors, and relying on photometric methods for the estimation of galaxy cluster redshifts. We examine the effects of systematic errors in scaling relation and measurement error assumptions. Using only  ( T , z )  self-calibration, we expect to measure Ω_m to ±0.03 (and  Ω_Λ  to the same accuracy assuming flatness), and σ₈ to ±0.05, also constraining the normalization and slope of the luminosity–temperature relation to ±6 and ±13 per cent (at 1σ), respectively, in the process. Self-calibration fails to jointly constrain the scatter and redshift evolution of the luminosity–temperature relation significantly. Additional archival and/or follow-up data will improve on this. We do not expect measurement errors or imperfect knowledge of their distribution to degrade constraints significantly. Scaling-relation systematics can easily lead to cosmological constraints 2σ or more away from the fiducial model. Our treatment is the first exact treatment to this level of detail, and introduces a new 'smoothed ML' (Maximum Likelihood) estimate of expected constraints.     

Vertical structure of the stable boundary layer detected by RASS-SODAR and in-situ measurements in SABLES 2006 field campaign

Data from the SABLES 2006 field campaign are used in order to analyse some of the main processes present along the nocturnal periods: surface-based inversions, low level jets, katabatic winds, wave-like motions, pressure perturbations, etc. These processes have an important influence on the vertical structure (both thermal and dynamical) of the atmospheric boundary layer, and can be better described with the synergetic combination of RASS-SODAR data and in-situ measurements (such as sonic anemometer data and high-resolution pressure series from microbarometers). It is shown how the different air masses and their evolution are easily identified when pressure and RASS-SODAR wind and temperature data are presented together. Likewise, periodic pressure fluctuations observed in the surface array of microbarometers reveal the existence of gravity wave motions whose propagation is better understood after locating the wave ducting layers with the help of RASS-SODAR average wind ant temperature profiles.     

Measuring the ecological integrity of an industrial district in the Amazon estuary, Brazil

The aim of the present study is to provide information on the ecological integrity of an industrial district located in the estuary of Pará River (Amazon estuary), by applying a selection of fish based multimetric indices of ecosystem integrity: Abundance Biomass Comparation (ABC); Biological Health Index; Estuarine Fish Community, Transitional Fish Classification and Estuarine Biotic Integrity Indexes. To evaluate the impacts of the industrial area and cargo terminal, three areas were considered: Zone 1, (maximum impact), Zone 2 (median risk) and Zone 3 (reference area). All the biological indices used were considered to be excellent indicators of the ecological integrity of the different sectors of the study area and were especially effective for the demonstration of the critical alterations of the fish community of Zone 1 and Zone 2. The simultaneous use of different indices family, with different assumptions, did strengthen the results enhancing the confidence in the diagnostic.     

Stable isotope study of cave percolation waters in subtropical Brazil: Implications for paleoclimate inferences from speleothems

We analyze the interannual monthly variability of oxygen isotope ratios in data from IAEA stations along the Atlantic coast of South America between 23° and 34° S to evaluate the influence of parameters such as temperature, rainfall amount and moisture source contribution on meteoric water recharging two karst systems in subtropical Brazil. In addition, a 2 year monitoring program performed on soil and cave drip and rimstone pool waters from sampling sites with contrasting discharge values and located at 100 and 300 m below the surface in the Santana Cave System (24°31′ S; 48°43′ W), is used to test the influence of hydrologic and geologic features on the temporal variations of seepage water δ¹⁸O.

Interannual monthly variations in δ¹⁸O of rainfall reflect primarily regional changes in moisture source contribution related to seasonal shifts in atmospheric circulation from a more monsoonal regime in summer (negative values of δ¹⁸O) to a more extratropical regime in winter (positive values of δ¹⁸O). Variations in groundwater δ¹⁸O indicate that the climatic signal of recent rainfall events is rapidly transmitted through the relatively deep karst aquifer to the cave drip waters, regardless of location of collection in the cave. In addition, the data also suggest that water replenishment in the system is triggered by the increase in hydraulic head during periods when recharge exceeds the storage capacity of the soil and epikarst reservoirs. Significant perturbations in the groundwater composition, characterized by more positive values of δ¹⁸O, are probably connected to an increased Atlantic moisture contribution associated with extratropical precipitation. This implies that the δ¹⁸O of speleothems from caves in this region may be a suitable proxy for studying tropical–extratropical interactions over South America, a feature that is intrinsically related to the global atmospheric circulation.     

Geochemical and statistical analysis of trace metals in atmospheric particulates in Wuhan, central China

The geochemical characteristics of trace metals (As, Cr, Co, Cd, Cu, Mn, Ni, Pb, V and Zn) in PM10 in Wuhan, the biggest metropolitan in central China, as well as their sources and contributions were analyzed. As PM10 has been the principal contaminant of air in Wuhan for years, concentrations of trace metals were measured in PM10 using high-volume samplers at one urban (Hankou) and one industrial (Changqian) site in Wuhan between September 2003 and September 2004. Based on the results, PM10 in Wuhan is characterized by relatively high levels of As, Cd, Mn, Pb and Zn compared with other Asian cities. The time-series of these elements indicated that As, Cu and Zn at both sites have similar trends, whereas Pb levels showed different patterns due to different emission sources. Factor analysis was applied to the datasets focusing on the apportionment of the mass of selected trace metals. Results indicate that Pb, Cd and As have a common source (smelting) at both sites, whereas the sources of Ni vary from coal combustion and steel in Changqian to mineral and traffic in Hankou.     

Characterization of a profile of residual soil from granite combining geological, geophysical and mechanical testing techniques

This paper summarizes the results of an experimental site investigation and characterization survey, on a residual (saprolitic) soil from granite, in the framework of a research project led by the Faculty of Engineering of the University of Porto (FEUP). This project aims at characterizing these unusual soils in the context of the development of an International Prediction Event (Class A) on the behaviour of different types of piles. A very extensive site characterization campaign, including a large variety of in-situ tests and field methods, has been held. These investigations comprised the application of several geophysical borehole and surface methods, namely P- and S-wave seismic refraction, reflection, cross-hole (CH), down-hole (DH), electrical resistivity imaging and ground probing radar (GPR), as well as mechanical tests, namely SPT, CPT and DMT, among others. The site is geologically formed by an upper layer of heterogeneous residual granitic soil, overlaying rather weathered granite contacting a gneissic migmatite. Direct and indirect results from some of the referred surveys were compared between them and with some of the available geological and geotechnical information, namely those obtained from seismic, electrical and GPR profiles, conducted adjacent to three boreholes in which undisturbed soil samples were collected previously to geophysical data acquisition. In addition, a comprehensive laboratory testing program was carried out using the collected undisturbed samples. A discussion of the obtained results is hereby presented, giving emphasis to the correlations encountered between the different tests, specific of saprolitic soils with weak relic structures.