Sources, distribution and variability of hydrocarbons in total atmospheric suspended particulates of two Brazilian areas influenced by sugarcane burning

Polycyclic aromatic hydrocarbons (PAHs) and aliphatic hydrocarbons (AHs), such as n-alkanes, hopanes and steranes, were studied in relation to total atmospheric suspended particulates (TSP). Two representative Brazilian cities affected by sugarcane monoculture practices, with their rural surroundings, were chosen for the study. The cities chosen were Maceió (state of Alagoas, NE-Brazil) and Campos dos Goytacazes (state of Rio de Janeiro, SE-Brazil). Samples were collected during the harvesting period, when sugarcane burning occurs, and during the non-harvesting period. The aliphatic hydrocarbon fingerprints suggest a marked contribution of biogenic inputs and a slight contamination by aliphatics in areas far from the urban regions. In the urban areas, some petroleum contributions were observed, marked by the presence of hopanes (m/z 191) and steranes (m/z 217) in the mass chromatographic profiles. A marked increase in PAH concentrations was detected during the sugarcane burning periods, mainly at Campos dos Goytacazes. In a similar approach, n-alkane concentrations and BaP/nC₂₄ ratios were higher during the sugarcane burning periods. These increases were mainly associated with PAH production by the pyrogenic process in relation to aliphatic hydrocarbons with the same carbon numbers. The PAH isomeric ratios and the mixture of petrogenic and pyrogenic compounds of the TSP suggest atmospheric contamination for all regions as a whole, but the more elevated pyrogenic contribution during the sugarcane burning period implies that the impact of this activity is relevant.     

Middle Terrace Deposits of the Tagus River in Alpiarça, Portugal, in Relation to Early Human Occupation

The stratigraphy and sedimentology of the Q3 middle terrace alluvial sequence in the lower Tagus river valley, Portugal, were studied near the village of Alpiarça, approximately 40 km upstream from the estuarine area. Two main stratigraphic units were recognized, separated by an important uncomformity. The Lower Gravels unit (LG) consists of intercalations of medium to coarse gravel deposits, mainly quartzitic, with coarse sandy matrix, organized in tabular bodies. The overlying Upper Sands unit (US) consists of tabular sandy channel deposits and overbank fines, the latter containing well-developed paleosols and backswamp deposits, showing a general aggrading trend, apparently with varying rates; available data indicate that deposition of the US took place under temperate climatic conditions. Within US deposits are several paleolithic archaeological sites, the lower ones in the alluvial stratigraphy being Middle Acheulian, whereas those embedded in overlying deposits are, from bottom to top, Upper Acheulian and Micoquian. Some of these sites have been recently excavated. The quartzite artifacts were apparently abandoned by early humans on the flood plain surface during deposition of the US unit and were subjected to limited reworking during their incorporation in the alluvium. TL/OSL dating of sandy-silty sediments, though imprecise, support archaeological evidence pointing to an age of 150,000 to 70,000 yr B.P. for the US unit.     

Rotation of Tokamak Plasmas by Alfvén Waves

Externally excited Alfvén waves can generate the poloidal and toroidal rotation in the collisional (edge) and core (weakly collisional) tokamak plasma. The necessary value of these velocities to achieve the L-H transition, can be obtained by manipulating the value of an absorbed power. This rotation linearly depends on dissipated power, decreases in banana regimes and did not depend on toroidal magnetic field. In the plasma layer where the RF power is absorbed, the radial electric field also appears. There is the very satisfactory agreement between our theory and experimental results obtained on Phaedrus-T tokamak. The methods developed in this paper can be applied to other tokamaks with another kind of waves, which can be used to operate the plasma dynamics taking into account the appropriate dispersion relation for that type of waves.     

Effect of Induced Toroidal Rotation on Poloidal Rotation and Ion Heat Conductivity of Tokamak Edge Plasmas

The transport processes in edge (collisional) plasmas of tokamaks with smooth profiles of macroscopic plasma parameters and induced poloidal and toroidal plasma flows, are considered. The toroidal and poloidal velocities of particles, the radial electric field and the ion heat flux are derived. It is shown that forces, induced by radio frequency waves, plasma turbulence or neutral beam injection, can be used to control the poloidal and toroidal plasma velocities, as well as ion heat conductivity, in a wide range of these values.     

Phytoremediation potential and morphological changes of plants growing in the vicinity of lead smelter plant

With the increasing industrialization, heavy metals concentration in soils has greatly increased. Phytoremediation is a low-cost, non-intrusive and aesthetically harmonious technology that uses plants to remediate contaminated sites by heavy metals. The aim of the study was to determine Cd, Pb and Zn concentration in the biomass of plant species growing on a multi-metal-contaminated site of lead smelter processing, to assess the workability of using these plants for phytoremediation purposes and highlight possible damage in morphological leaf changes. Two plant species, i.e., Ipomoea asarifolia and Urochloa decumbens and the associated soil samples were collected and analyzed Cd, Pb and Zn concentrations and then calculating the bioconcentration factor and translocation factor parameters for each element. Leaves and roots samples were observed by light microscopy. Metal concentrations varied greatly and majorly depend on site sampled, plant species and tissue. Cd, Pb and Zn in tissue ranged from 0 to 102.48, 0 to 381.04 and 12.84 to 295.02 mg Kg^?1. However, none of the plant showed potential for hyperaccumulation. Both plants showed bioaccumulation factor more than one, where it was 7.66 and 6.82 for Pb and Zn in U. decumbens, respectively. Translocation factor was calculated below one for both plants and all metals. Morphological studies revealed development of adaptive features that strengthen the U. decumbens to grow in contaminated soil. Our study suggests that I. asarifolia and U. decumbens have potential for phytostabilization at multi-metal-contaminated site.     

Coronal loop heating by discrete Alfvén waves

We have modeled the solar coronal active loop heating by discrete Alfvén waves. Discrete Alfvén waves (DAW) are a new class of Alfvén waves which can be described by the two-fluid model with finite ion-cyclotron frequency, or the MHD model with plasma current along the magnetic field line as shown by Appert, Vaclavik, and Villar (1984). We have modeled the coronal loop as a semi-toroidal plasma with the major toroidal radius much larger than the plasma radius. We have shown that the absorption of discrete Alfvén waves by the plasma through viscosity can account for at least 30% of the coronal heating rate density of 10^–4 J m^–3 s^–1.     

Spatial and temporal variability of seawater properties,current velocity and SPM concentration off Cassino Beach-Rio Grande-Southern Brazil

Water column profiles and near-bed time series of pressure, current velocity, suspended-particulate matter (SPM) concentration and seawater temperature and salinity were collected during three short cruises carried out in May 2005 in the shoreface and inner shelf area adjacent to Cassino Beach, southern Brazil. The measurements were part of the Cassino Experiment, a project conducted at an open, sandy coastal area known for the occurrence of patches of fairly large amounts of muddy sediments that are sporadically fluidized, transported onshore and eventually stranded on the beach. The study area is close to the Patos Lagoon mouth, being influenced by its water and suspended-sediment discharge. The presence of the Patos Lagoon outflow on the inner shelf was detected in one of the cruises (May 13) through measurements of near-surface salinity: while close to shore salinity was 29.4, a minimum value of 13.8 was measured at ∼10 km from the coast. Four days later, no trace of the plume was detected in the area. Regarding seawater temperature, no large temporal or spatial variability was documented with measured values ranging from 19.3 to 20 °C. Water column currents were prominently to N and NE, except at the outermost station, located ∼42 km from the coast, where NW-directed flows were observed at surface and mid-depth. Maximum near-bed current velocity oscillated between 18 and 42 cm s⁻¹ in the east–west direction and between 14 and 42 cm s⁻¹ in the north–south direction. Near-surface concentration of SPM oscillated between 11 and 99 mg L⁻¹, in general one order of magnitude lower than near-bed values. However, near-bed concentration of SPM showed large spatial variability: the highest value (2200 mg L⁻¹) was yielded by a water sample collected at ∼8 m water depth, at a station located ∼2 km away from the shoreline; two water samples collected 500 m, apart from this station, yielded SPM concentrations of 148 and 205 mg L⁻¹, one order of magnitude lower. Spectral analyses of near-bed current speed and SPM concentration indicate the relevance of oscillations in the low-frequency (<0.05 Hz) range. Detailed sampling of bottom sediment indicated that in May 2005 the mud patch was centered at ∼8.5 m water depth.     

Geostatistical Seismic Inversion with Direct Sequential Simulation and Co-simulation with Multi-local Distribution Functions

Stochastic sequential simulation is a common modelling technique used in Earth sciences and an integral part of iterative geostatistical seismic inversion methodologies. Traditional stochastic sequential simulation techniques based on bi-point statistics assume, for the entire study area, stationarity of the spatial continuity pattern and a single probability distribution function, as revealed by a single variogram model and inferred from the available experimental data, respectively. In this paper, the traditional direct sequential simulation algorithm is extended to handle non-stationary natural phenomena. The proposed stochastic sequential simulation algorithm can take into consideration multiple regionalized spatial continuity patterns and probability distribution functions, depending on the spatial location of the grid node to be simulated. This work shows the application and discusses the benefits of the proposed stochastic sequential simulation as part of an iterative geostatistical seismic inversion methodology in two distinct geological environments in which non-stationarity behaviour can be assessed by the simultaneous interpretation of the available well-log and seismic reflection data. The results show that the elastic models generated by the proposed stochastic sequential simulation are able to reproduce simultaneously the regional and global variogram models and target distribution functions relative to the average volume of each sub-region. When used as part of a geostatistical seismic inversion procedure, the retrieved inverse models are more geologically realistic, since they incorporate the knowledge of the subsurface geology as provided, for example, by seismic and well-log data interpretation.