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Copyright of Revista Brasileira de Engenharia Agricola e Ambiental - Agriambi is the property of Revista Brasileira de Engenharia Agricola e Ambiental and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The steel industry in Brazil is responsible for around 5% of total carbon dioxide emissions, releasing around 1.85 tons of CO 2 for every ton of steel produced. The use of charcoal in self-reducing iron ore briquettes can be an alternative to reduce fossil fuel consumption and reduce carbon emissions in the primary steelmaking industry, however, the particle size can affect the reduction process. This study aims to analyze the reduction kinetics of charcoal briquettes in three particle size ranges. To this end, the charcoal was characterized using thermogravimetric analysis to determine the contents of fixed carbon, ash and volatiles, analysis of sulphur in the charcoal by combustion in a tube furnace, determination of particle size by laser granulometer, elemental chemical analysis of the charcoal ash by X-ray fluorescence spectrometry. The briquettes were reduced in a thermogravimetric balance to 1100 °C with heating rates between 10 and 40 °C/min. They were characterized by X-ray diffraction. Finally, a kinetic study was carried out using the Coats-Redfern method. In all the briquettes, the controlling mechanism was diffusion. In the mixture with fines, the activation energy ranged from 31.95 to 33.72 kJ/mol and 120.29–137.17 kJ/mol. For the mixture with medium grain size, the activation energy ranged from 58.1 to 89.42 kJ/mol and 107.83–153.50 kJ/mol. X-ray diffraction revealed phases of hematite and magnetite at 800 °C, while at 900 °C phases of wustite and faialite and metallic iron were identified. • Particle size affects self-reducing briquette's reaction rate in iron ore reduction kinetics. • Charcoal-based briquettes offer a viable solution for sustainable steel production, reducing fossil fuel use. • The activation energy increases in the second stage of the briquette reduction process. [ABSTRACT FROM AUTHOR]

Most soil databases present the mass fractions of sand, silt, and clay particles without detailed primary particle-size distribution (PSD). In the present paper two simple methods are introduced to estimate the PSD using the fractions of sand, silt, clay, and very coarse sand. A total of 504 soil samples with different texture classes from different regions, i.e., southern Iran (245), south-eastern Brazil (116), and UNSODA database (143) were used. PSD of the Iranian and Brazilian soil samples were determined using a combination of wet-sieving and sedimentation (hydrometer for Iranian and pipette for Brazilian soils) approaches and that of the others extracted from UNSODA database. We developed two new methods including very coarse sand-dependent (VCS-D) and very coarse sand-independent (VCS–I) to predict PSD of the soils. PSD were also predicted using the revised Skaggs method (R-Skaggs) and compared with the measured ones. Both VCS-D and VCS-I approaches with very simple equations accurately estimated full range of PSD in a wide range of the fine to medium textured soils)clay, clay loam, loam, silty clay, silty clay loam, silt loam, and silt texture classes). Accuracy of predictions was slightly lower in coarse textured soils (sandy clay, sandy clay loam, sandy loam, loamy sand, and sand textures) than that of the other texture classes. For these coarse textured soils, it is strongly recommended that the fraction of particles between 0.05 and 2 mm diameters be estimated using the VCS-D or VCS-I methods and the fraction of particles between 0.002 and 0.05 mm diameters be estimated using the R-Skaggs method. The R-Skaggs method could only predict the PSD in the soils with nearly 25–60% sand content, accurately. Whereas, the new proposed methods could predict full range of PSD with high accuracy (NRMSE <10%) in soils with sand content less than 53%. Overall, the proposed methods could accurately predict full range of PSD curve by using only the content of primary soil particles in nearly 73% of soil classes in texture triangle. • New methods (VCS-D and VCS-I) proposed to estimate particle-size distribution (PSD). • The methods are very simple and accurate to estimate PSD from limited texture data. • The methods are very accurate to estimate PSD in 73% of soil texture triangle. • The methods excellently estimate PSD in fine and medium textured soils. • The methods were more accurate than R-Skaggs in fine and medium textured soils. [ABSTRACT FROM AUTHOR]

The state of Espírito Santo is the major producer of Coffea canephora in Brazil. Knowledge of genetic reserves is fundamental to plant breeding. Therefore, the present study characterized and analyzed the genetic diversity of 600 C. canephora accessions from the germplasm bank of Incaper based on 38 traits evaluated in 24-30-month-old plants. Further, the predominant descriptors or traits were identified, and high phenotypic variability was determined. Genetic distances for the grouped (Gower), quantitative, and qualitative datasets were 0.48, 0.61, and 0.92, respectively, with accessions 76 (Conilon) and 407 (Robusta) being the most divergent ones at Incaper. In clustering using the Tocher optimization method, 30 groups were formed, with three accessions introduced from Epamig's Robusta collection being the most dissimilar ones. Graphical dispersion analysis using the principal coordinate method revealed the predominance of three groups formed by the Robusta, Conilon, and hybrid Robusta × Conilon genotypes. [ABSTRACT FROM AUTHOR]

Anthracnose, caused by Elsinoë ampelina, is an economically important grapevine disease in south and southeast Brazil. Control is achieved by lime sulphur application during grapevine dormancy and foliar fungicide sprays until the berries are half‐grown. This study assessed the temporal and spatial progress of grapevine anthracnose under field conditions in order to describe the disease dynamics and its relationship to pathogen survival. The experiment was carried out in a vineyard of table grape Vitis labrusca in Brazil, during the 2014 and 2015 growing seasons. The incidence of vines with diseased leaves, stems and berries and the disease severity on leaves were recorded from bud break to veraison. Monomolecular, logistic and Gompertz models were fitted by non‐linear regression to the incidence and severity data over time to characterize the temporal progress. Ordinary runs, dispersion index, modified Taylor's power law and spatial hierarchy analyses were used to characterize the spatial pattern of diseased plants. The monomolecular model showed the best fit for the incidence progress, with disease progress rates ranging from 0.051 to 0.136 per day. In both seasons, the incidence of diseased plants reached 100% 1 month after bud break. However, the incidence of diseased leaves per plant was around 60% and leaf disease severity was lower than 5% for both years. Ordinary runs and dispersion index analyses revealed that diseased grapevines were distributed randomly on the majority of the assessment dates. Meanwhile, a slight aggregation of diseased vines was observed in the modified Taylor's power law analysis. Our results suggested that the progress of anthracnose incidence and severity over time was governed mainly by the income of the primary inoculum, which survived in the vineyard. Therefore, anthracnose control measures in Brazilian vineyards should be focused on the reduction in inoculum within the vineyard. [ABSTRACT FROM AUTHOR]

Copyright of Revista Brasileira de Engenharia Agricola e Ambiental - Agriambi is the property of Revista Brasileira de Engenharia Agricola e Ambiental and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The purpose of this work is to present suitable statistical methods to study the performance of undergraduate students based on the incidence/proportion of failed courses/subjects. Three approaches are considered: first, the proportion of failed subjects is modeled considering a zero-one augmented beta distribution; second, discrete models are used to model the probability of failing subjects with logit link; third, incidence is modeled using regression for count data with log link and the logarithm of the total number of subjects as an offset. Zero-inflated versions are used to account for the excess of zeros in the data when appropriate and we also considered the heterogeneous dispersion parameter, when applicable. Overall, the zero-inflated negative binomial and zero inflated beta-binomial models, with regression on the mean and the dispersion parameters, present good measures of goodness of fit to the data. The database consists of records of Engineering major students who entered the State University of Campinas, Brazil, from 2000 to 2005. Entrance exam scores and demographic variables as well as socio-economic status are considered as covariates in the models. [ABSTRACT FROM AUTHOR]

We investigated the adsorption of glyphosate onto five subtropical soils of Paraná and São Paulo states, Brazil, a region of intense agricultural activities, aiming at the determination of kinetic and isotherm adsorption parameters which enable the evaluation of the potential leaching of the herbicide. The adsorption was fast, being described by the pseudo-second order and intraparticle diffusion models, thus suggesting that mixed mechanisms are involved. The Oxisol containing the highest concentrations of metal oxides (209.5 g kg−1 Fe2O3 and 160.2 g kg−1 Al2O3) was the sample with the highest rate constant, indicating the adsorption sites are readily available. All the soils are rich in aluminum and iron oxides, explaining the Freundlich coefficients (KF) between 642 and 1360 mg1-1/n kg−1 L1/n, which are higher than most of the coefficients described for other soils around the world. The maximum desorption (15% of the adsorbed amount) was observed for the Oxisol. For the other soils, desorption ranged from 2 to 7%. These results suggest that the leaching of free glyphosate to nearby surface and groundwaters is unlikely unless excessive doses are used. The adsorption parameters are useful for managing the right doses applied to the crops, thus avoiding contamination of adjacent areas. [ABSTRACT FROM AUTHOR]

The energy generated by Small Hydroelectric Plants (SHPs) is sold in Brazil using a Physical Energy Guarantee, also known as a Power Purchase Agreement (PPA), the maximum amount of energy that a generator can sell. The PPA is calculated based on monthly average flow series data, however, studies have shown that this can overestimate the PPA and that daily average flow series data are more accurate in reflecting the amount of generated electric energy. Unlike other hydrological evaluations, the uncertainty levels associated with the data used to calculate the PPA at SHPs are neither considered nor quantified. This study investigates the impact of hydrological uncertainties on SHP PPAs. The Monte Carlo method was used to analyze the uncertainty levels for an SHP case study. It has been elaborated 2 models, where the results show that the models have on average an upper deviation of 1.30 MW from current PPA and a lower deviation of 1.19 MW from the current PPA. Dispersion analysis revealed that SHPs with smaller installed capacities and lower PPAs faced more business risks than SHPs with higher PPAs, which are generally more thoroughly evaluated by investors. [ABSTRACT FROM AUTHOR]

In this work the urban area of Aracaju city, located in the State of Sergipe, Northeastern Brazil was the site for simultaneous collection of suspended particles (TSP) and inhalable particulate matter (PM 10) aiming an evaluation of the air quality parameters. Concentrations of Cd, Co, Cu, Fe, Mn, Ni, Pb and V in TSP and PM 10 were determined by inductively coupled plasma mass spectrometry (ICP-MS). Iron was the most abundant element found in both particulate samples. Through chemometric tools, it was possible to point out that the contributions to the TSP and PM 10 formation are similar, and strong correlations were observed between Fe-Mn (0.83) and Cd-Pb (0.93) in TSP, and Fe-Mn (0.90), Fe-Cu (0.81) and Cd-Pb (0.97) in PM 10 , an evidence that these species are from sources related mainly to soil resuspension and vehicular traffic. Enrichment factor (EF) and geoaccumulation index (I geo) showed an influence of fossil fuel burning in the composition of TSP and PM 10. Through principal component analysis (PCA) and hierarchical cluster analysis (HCA) it was observed particle size distribution groupings according to its aerodynamic size. Evaluation of the concentrations obtained for the collected samples according to the seasons (dry and rainy), indicated the influence of both, biogenic (resuspension of soil and marine aerosols) and anthropic (vehicle traffic and biomass burning) sources. Image 1 • Study considering seasonal source of TPS and PM 10 in Aracaju city was investigated. • Concentrations of Cd, Co, Cu, Fe, Mn, Ni, Pb and V in TSP and PM 10 were determined. • Enrichment factor and geoaccumulation index were calculated for airborne trace elements. • Concentrations of Cu, Pb, Cd and Co suggest anthropic contribution. • Correlations between Fe-Cu and Fe-Mn showed a relation to natural sources. [ABSTRACT FROM AUTHOR]

Grasslands and wetlands are non-forested highly biodiverse ecosystems. Although fire is a major factor controlling and maintaining biodiversity in different landscapes of Central Brazil, there are still knowledge gaps about its effect on these systems. We compared composition, diversity and coverage of herbaceous and sub-shrub species in 'campos de murundus' (murundus fields) before and after recurrent fire events. We sampled and collected species in 32 subplots of 1 m2 within a 100 × 100 m plot, and compared species richness, diversity, frequency, and cover percentage before and after recurrent fires. Floristic composition was evaluated through multivariate dispersion analysis. Our results show that recurrent fires in murundus fields decreased species richness and modified the composition of herbaceous and sub-shrub (i.e., species with a woody base and soft shoots) species. However, species diversity either increased or was maintained, depending on the diversity index used. In addition, repeated fire events modified the coverage and increased the dominance of fire-tolerant species, such as Aristida pendula, over fire-sensitive ones, such as Eriocaulon burchellii, Eleocharis minima, Hyptis hygrobia, Scleria sp., Paspalum lineare, Piriqueta sp., Polygala celosioides and Sipanea biflora. These post-fire changes resulted in altered species composition, richness and soil cover. Generally, fire increased the amount of bare ground and, consequently, decreased species richness and species diversity. [ABSTRACT FROM AUTHOR]

Copyright of Revista Brasileira de Engenharia Agricola e Ambiental - Agriambi is the property of Revista Brasileira de Engenharia Agricola e Ambiental and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Soils from the remote areas of the Amazon Rainforest in Brazil are poorly mapped due to the presence of dense forest and lack of access routes. The use of covariates derived from multispectral and radar remote sensors allows mapping large areas and has the potential to improve the accuracy of soil attribute maps. The objectives of this study were to: (a) evaluate the addition of relief, and vegetation covariates derived from multispectral images with distinct spatial and spectral resolutions (Landsat 8 and RapidEye) and L-band radar (ALOS PALSAR) for the prediction of soil organic carbon stock (CS) and particle size fractions; and (b) evaluate the performance of four geostatistical methods to map these soil properties. Overall, the results show that, even under forest coverage, the Normalized Difference Vegetation Index (NDVI) and ALOS PALSAR backscattering coefficient improved the accuracy of CS and subsurface clay content predictions. The NDVI derived from RapidEye sensor improved the prediction of CS using isotopic cokriging, while the NDVI derived from Landsat 8 and backscattering coefficient were selected to predict clay content at the subsurface using regression kriging (RK). The relative improvement of applying cokriging and RK over ordinary kriging were lower than 10%, indicating that further analyses are necessary to connect soil proxies (vegetation and relief types) with soil attributes. [ABSTRACT FROM AUTHOR]

The quality of particle size analysis is essential for correct soil textural classification and defining the Brazilian Agroclimatic Zoning. The objectives were to evaluate methods of particle size analysis and develop a spreadsheet for use in quality control analyzes. We collected 50 soil samples with different particle size distribution, in RS and SC states of Brazil, which were analyzed by five laboratories in the two states that perform the soil particle size analysis using two methods: one proposed by the Campinas Agronomic Institute (IAC) and the other by the Network of Soil and Plant Tissue Analysis Laboratories of the states of RS and SC (ROLAS). A greater number of disparities were observed for the clay and sand fractions regardless of the method. The ROLAS method had a higher number of mismatches (76% of samples), especially for samples with higher contents of those two fractions. The use of the median value in the ROLAS methodology is more rigorous in analysis quality control. [ABSTRACT FROM AUTHOR]

The aim of this paper is to present and discuss the air dispersion parameters determined for industrial Brazilian flotation circuits. The rougher and scavenger circuits of RPM, Taquari-Vassouras, Copebras and Fosfertil-Catalão (today Vale Fertilizantes) were investigated. For RPM and Taquari-Vassouras, the superficial gas velocity (Jg), gas hold-up (&egr;g), bubble size diameter (d32) and superficial area bubble flux (Sb were measured, whereas only the Jg and &egr;g were measured in the other circuits. The results pointed out that, except for RPM, all the circuits presented very low values for the air dispersion parameters. Taquari-Vassouras presented the lowest values for average Jg and gas hold-up: 0.05 cm/s and 5%, respectively. The highest value was presented for the rougher circuit of Cope-bras, 1.17cm/s, while RPM presented the highest values for &egr;g and bubble size, respectively 31% and 2.61mm. In the circuits where the calculation of the Sb parameter was possible, the results obtained lay in a range lower than those re-ported in literature. [ABSTRACT FROM AUTHOR]

In order to improve manganese-iron alloy production processes, an important Brazilian manganese ore typology, placed in Carajás, PA, was characterized. A representative sample was obtained from mine. The particle size determination was performed by screening, followed by chemical analysis using plasma spectrometry (ICP-AES). The physical properties studied included density, surface area and porosity measurements (BET). The mineral constituents was identified and quantified by X-ray diffraction. A termogravimetrical study was done in order to verify the thermal stability of major mineral constituents in the air. It was observed that 19.3% of studied typology was below 6.3mm. The manganese, silica and phosphorus contents were 52.63%, 1.92% and 0.17%, respectively. The oxides identified were cryptomelane, todorokite and pyrolusite. The other constituents were goethite, quartz, gibbsite, and kaolinite. According to the thermal study, the cryptomelane and pyrolusite start their decomposition in the air, at approximately 600°C. At around 950°C, Mn2O3 decomposition and Mn3O4 growth were observed. [ABSTRACT FROM AUTHOR]

Background, aim and scope Studies of particulate-associated pollutants, or PAPs, in urban areas have become necessary due to their potentially deleterious effects on the environment. However, it is not just the sediments themselves which are problematic but also their particle size composition, which has a great influence on their capacity to adsorb and transport pollutants. This paper presents the particle size distributions and concentrations of five metals (Cr, Cu, Ni, Pb and Zn) of urban sediments collected from paved streets and gully pots from 20 cities in southern Brazil. The cities have different characteristics and hence sources of PAPs associated with differing geologies, soil types and type of urbanisation. Studies of this nature enable elucidation of the relationship between diffuse sources such as streets and gully pots and the likelihood of PAPs to subsequently pollute the urban aquatic environment. Materials and methods Sediment samples were taken at random from paved streets and gully pots in 20 cities in Rio Grande do Sul state, southern Brazil by means of a portable vacuum cleaner to avoid loss of finer particles. The particle sizes of the samples were measured using a Cilas® 1180 laser particle analyzer, and the concentrations of five metals (Cr, Cu, Ni, Pb and Zn) were determined by wet acid digestion (HCl-HF-HClO4-HNO3) followed by inductively coupled plasma atomic emission spectroscopy on the <63-μm fraction. Results It was found that in comparison to sediments collected from the streets, gully pot sediments were more heterogeneous in terms of particle size and also that sediment samples from the gully pots were predominantly coarser than those originating on the streets. From the gully pot results, analysis of the modal particle diameter enabled the cities to be divided into three categories. The concentrations of metals in the street sediments were similar across all 20 cities, with all concentrations above background values. Discussion The fact that concentrations of metals in the street sediments were above statutory guideline values and that the coarser material was deposited in the gully pots suggests that the finer, more polluted sediment is not retained in the gully pots but is transported to the nearest local receiving watercourse. This finding has implications for management strategies for reducing pollution in urban environments. Conclusions High concentrations of Cr, Cu, Ni, Pb and Zn in the <63-μm fraction of street sediments, in combination with coarse material retained in the gully pots, indicate that metals could be transferred quite rapidly from the diffuse source of pollutants, on impermeable street surfaces, to receiving watercourses. Recommendations and perspectives Studies of urban sediment particle size and geochemistry enable predictions to be made of sediment behaviour in urban environments. This will inform management strategies such as the possibility of including sustainable urban drainage systems in future management plans, in which it is useful to know how efficient the drainage system is from the point of view of sediment deposition in the urban aquatic environment and the potential for pollution of receiving waters. [ABSTRACT FROM AUTHOR]

This paper reports on a preliminary evaluation of the grain size distribution of cadmium, lead and copper in sediment from Catarina Beach, Ilha Solteira, in the state of Sao Paulo, Brazil. Surface sediments were fractionated with < 63 μ m nylon sieves and subjected to three digestion procedures: the proposed open digestion, the standard USEPA-3050B and closed digestion in a Teflon tube. The metals were determined by atomic absorption spectrometry. The results of the three procedures showed no significant differences. The 309 mg Kg1 concentration of copper found at the P3 sampling point exceeded the PEL (probable effect level) value of 197 mg Kg1, which represents an environmental hazard to aquatic organisms. The sediments organic matter content determined by the loss on ignition was 6.8, 1.7 and 0.6% in the P3, P1 and P2 samples, respectively. The distribution of metal concentrations in sieved sediment followed the order P3 < P2 < P1 thereby suggesting an interaction with organic matter. [ABSTRACT FROM AUTHOR]

A system comprising a UASB reactor, shallow polishing ponds and shallow coarse filters, treating actual wastewater from the city of Belo Horizonte, Brazil, has been evaluated. The main focus of the research was to compare grain sizes and hydraulic loading rates in the coarse filters. Two filters operating in parallel were investigated, with the following grain sizes: Filter 1 : 3 to 10 cm; Filter 2:8 to 20 cm. Two hydraulic loading rates were tested: 0.5 and 1.0 m³/m³.d. The filter with the lower rock size had a better performance than the filter with the larger rock size in the removal of SS and, as a consequence, BOD and COD. A better performance was obtained with the hydraulic loading rate of 0.5 m³/m³.d, as compared to the rate of 1.0 m³/m³.d. The effluent quality during the period with the lower loading rate was very good for discharge into water bodies or for agricultural reuse (median effluent concentrations from Filter 1 : BOD: 20 mg/L; COD: 106 mg/L; SS: 28 mg/L; E. coil: 528 MPN/100 mL). [ABSTRACT FROM AUTHOR]

The concentrations of PM2. 5−10, PM2. 5 and associated water-soluble inorganic species (WSIS) were determined in a coastal site of the metropolitan region of Rio de Janeiro, Southeastern Brazil, from October 1998 to September 1999 (n=50). Samples were dissolved in water and analyzed for major inorganic ions. The mean (± standard deviation; median) concentrations of PM2. 5−10 and PM2. 5 were, respectively, 26 (± 16; 21)μgm−3 and 17 (± 13; 14)μgm−3. Their mean concentrations were 1. 7–1. 8 times higher in dry season (May–October) than in rainy season (November–April). The WSIS comprised, respectively, 34% and 28% of the PM2. 5−10 and PM2. 5 masses. Chloride, Na+ and Mg2+ were the predominant ions in PM2. 5−10, indicating a significant influence of sea-salt aerosols. In PM2. 5, SO4 2− (∼97% nss-SO4 2−) and NH4 + were the most abundant ions and their equivalent concentration ratio (SO4 2−/NH4 + ∼1. 0) suggests that they were present as (NH4)2SO4 particles. The mean concentration of (NH4)2SO4 was 3. 4μgm−3. The mean equivalent PM2. 5 NO3 − concentration was eight times smaller than those of SO4 2− and NH4 +. The PM2. 5 NO3 − concentration in dry season was three times higher than in rainy season, probably due to reaction of NaCl (sea salt) with HNO3 as a result of higher levels of NO y during the dry season and/or reduced volatilization of NH4NO3 due to lower wintertime temperature. Chloride depletion was observed in both size ranges, although more pronouncely in PM2. 5. [Copyright &y& Elsevier]

Arsenic distribution and dispersion in sediments of the Engenho Inlet and the Sepetiba Bay were investigated in order to evaluate the extent of the contamination caused by a metallurgical plant installed in the Sepetiba Bay watershed. The ore used in the smelting process, the soil around the plant, and ore waste collected inside the plant were also analyzed for As. Very high As concentrations in the strongly and weakly bound fractions (up to 63 000 and 52 700 μg g-1, respectively) were found in the ore waste. The soils also contained high concentrations of both the strongly and weakly bound fractions (748 and 636 μg g-1, repectively), although the ore itself contained lower levels of the two fractions (63 and 13 μg g-1, respectively). The sediments of the Engenho Inlet had a high degree of contamination (up to 347 μg g-1) decreasing toward Sepetiba Bay where the lowest concentrations were found (up to 50 μg g-1). Altough lower concentrations were found in the Sepetiba Bay sediments, they are 5 times higher than the world average. The results showed that there is an As transport from the Engenho Inlet to the Sepetiba Bay. These results suggests that the bay's fish and mollusk stock my be contaminated. This contamination may adversely affect the health of the local population, whose main protein supply is seafood. [ABSTRACT FROM AUTHOR]

The Butiazal de Tapes (30°31′39.86″S, 51°21′31.02″W) region is located in southern Brazil on the western shore of the Patos Lagoon and presents a remnant of a native palm grove ecosystem known as butiazal. It is characterized as savanna dominated by palm trees from the Butia genus, and spreads throughout southern Brazil, Uruguay and Argentina. Species from this genus are threatened by monoculture and livestock farming. In this region there are outcrops of Pleistocene coastal deposits which were exposed to the Holocene climate and to the influence of coastal dynamics. It is therefore an excellent location for palaeoclimatic and palaeoenvironmental reconstruction of the past 11,000 years. For such a reconstruction, and better understanding as to how this unique ecosystem was formed, tools such as bioindicators (phytoliths and palynomorphs), X-ray diffractometry analysis, total organic matter content determination, particle size analysis and carbon-14 AMS dating were used. Indications of the presence of Butia in the region from at least 11,125 to 10,751 yr cal BP were identified, along with the importance of the climate during its formation and expansion. Although the climate changes in the analysed interval were not expressive, it was possible to divide the profile into 4 zones according to plant cover and observe the influence of sea-level shifts during the Holocene on the evolution of the palaeoenvironment in the region, besides the evident human influence on vegetation evolution. • Variations in sea level can be detected through changes in vegetation evolution. • The ecosystem butiazal has been in the west shore of Patos Lagoon since at least 4154-3960 yr cal BP. • Butia odorata (Barb. Rodr.) Noblick responds well to phytolith analysis. • There are evidences of anthropic management in the evolution of "Butiazal de Tapes". [ABSTRACT FROM AUTHOR]

• This paper was to characterize the dynamics and spatial aspects of erodibility. • Texture governs higher or lower loss rates according to grain size. • Cultivated IBEs exhibit moderate to high soil loss rates, mainly by runoff. • Texture and organic matter control susceptibility to water erosion in IBEs. • Erodibility factors showed spatial dynamics moderately influenced by relief. Soil erosion generally causes environmental and economic damage to agricultural systems, representing one of the biggest management problems for agriculture. Therefore, understanding the behavior of the erosive process is indispensable for the diagnosis of best conservationist practices of use and management of agricultural resources. The aim of this paper was to characterize the dynamics and spatial aspects of erodibility, its indicators and to evaluate the applicability of the prediction equations of soil loss proposed by Denardin (1990) and Flanagan and Livingston (1995) for cultivated and natural Indian Black Earths (IBEs). Grids with 88 georeferenced sampling points were established for soil sampling at a depth of 0.0–0.20 m. Laboratory analyzes were performed to determine soil particle size and soil organic matter (SOM) analysis. The erodibility factors were calculated and applied univariate analysis, geostatistics and multivariate techniques. Cultivated IBEs exhibit moderate to high soil loss rates even in low slope relief, mainly by runoff. The dynamics of the erodibility factors behave under moderate spatial dependence between the attributes, with high range values and moderate relief influence, indicating high spatial variability, showing the tendency of values of soil losses similar to distances between 15 and 69 m. However, texture and organic matter were the main indicators of erodibility, since medium texture IBEs tend to increase the global and interril erodibility values, and under sandy texture tend to increase erodibility in gully. The increase in SOM elevates erodibility and interril due to the high amount of pyrogenic coal with high capacity to retain water. Therefore, we recommend the adoption of management practices that reduce erosion processes, and mainly avoid the loss of mineralized SOM to maintain crop sustainability. [ABSTRACT FROM AUTHOR]

Decaying plant material is the major source of soil organic carbon (SOC). Nevertheless, it still remains unclear how the biochemical composition of litter is affecting the formation of SOM. Thus, we aimed to disentangle the effect of plant litter composition on C transference into differently stabilized soil fractions. We did this by individually incubating 13C enriched Eucalyptus spp. organs (bark, leaves, twigs and roots) in topsoil (0–20 cm) of a sandy-clay loam (Haplic Ferralsol) from Paula Candido – Brazil (20º 52' S, 42º 58' E). Additionally, a soil sample without plant residue addition was incubated and used as a control. The samples were incubated at 80% of their water-holding capacity at 25 ºC. The molecular composition of the incubated plant organ material was characterized by solid-state 13C-CP/MAS-NMR spectroscopy. At the end of the incubation experiment (after 200 days), aliquots were taken and the SOM was physically fractionated using a combined density-particle size separation method. The total C content and the relative abundance of 13C (δ 13C) of each soil organic matter fraction were measured by IRMS, whereas the litter-C contribution for each SOM fraction was assessed using a two-end member isotope mixing model. No significant differences were observed for total SOC contents among the different treatments. Conversely, lower total SOC contents were observed for the control treatment without residue addition, indicating mineralization of inherited SOM along the incubation period. The partitioning of litter-derived C into SOM fractions and CO2 indicates that leaf had higher proportion of C transferred to the total SOC, followed by roots, bark and twigs. The amount of carbon transferred to the mineral associated organic matter (MAOM) was as follows: leaves > bark > twigs > roots. Contrastingly, for the particulate organic matter (POM) the order was as follows: roots > bark > twigs = leaves. Contrasting NMR spectra demonstrate the significant effect of the biochemical composition of each plant organ in the fate of C in soil. Carbon from leaves was preferentially allocated to the MAOM fraction, and was more enriched in carboxyl and alkyl groups. Twigs, bark and roots, which were more enriched in O-Alkyl group, were preferentially respired or allocated into the POM fraction. [ABSTRACT FROM AUTHOR]