Soil corrosion of the AISI1020 steel buried near electrical power transmission line towers

Soil corrosion of carbon steel samples buried up to hundred days close to a high voltage power transmission line tower was examined by weight loss vs. time. A higher weight loss was observed if the samples were electrically connected to the tower than if they were not. This was attributed to the influence of alternating current (AC) signals induced in the soil by the transmission line. This field study showed for the first time the influence of the AC power line on the buried structure of the tower, while other studies so far were focused only on AC corrosion of cathodically protected coated pipelines, running parallel to the transmission line. An improved method was used to measure weight loss by descaling in Clark solution. The new method substitutes discontinuous measurements, proposed in the ASTM-G1-90 standard, by in situ measurements of the weight loss during descaling, using a computer controlled microbalance

Mineralogy of the clay fraction of alfisols in two slope curvatures: IV - spatial correlation with physical properties

A influência da mineralogia da fração argila nos atributos físicos do solo é reportada na literatura; porém, as relações espaciais entre esses atributos são escassas em se tratando de Argissolos. O objetivo deste trabalho foi avaliar a correlação espacial entre os minerais da fração argila e atributos físicos de um Argissolo de origem arenítica. Os atributos mineralógicos como diâmetro médio do cristal (DMC); largura à meia altura (LMA) dos minerais hematita, goethita, caulinita e gibbsita; teor; substituição isomórfica (SI); área de superfície específica (ASE) dos minerais hematita e goethita; razão goethita/(goethita+hematita); e razão caulinita/(caulinita+gibbsita) foram correlacionados com os atributos físicos por meio da correlação simples de Pearson e dos semivariogramas cruzados entre esses atributos. As relações encontradas entre a substituição isomórfica da goethita e os atributos físicos do solo permitiram inferir sobre o efeito da cristalinidade desse mineral nos atributos físicos do solo. Goethitas com altos valores de substituição isomórfica favoreceram a dimensão dos agregados e da porosidade; o contrário ocorreu com a densidade do solo (Ds) e resistência a penetração (RP). Gibbsitas de maior grau de cristalinidade favoreceram os maiores valores de densidade do solo e RP.Although the influence of clay mineralogy on soil physical properties has been widely studied, spatial relationships between these features in Alfisols have rarely been examined. The purpose of this work was to relate the clay minerals and physical properties of an Alfisol of sandstone origin in two slope curvatures. The crystallographic properties such as mean crystallite size (MCS) and width at half height (WHH) of hematite, goethite, kaolinite and gibbsite; contents of hematite and goethite; aluminium substitution (AS) and specific surface area (SSA) of hematite and goethite; the goethite/(goethite+hematite) and kaolinite/(kaolinite+gibbsite) ratios; and the citrate/bicarbonate/dithionite extractable Fe (Fe d) were correlated with the soil physical properties through Pearson correlation coefficients and cross-semivariograms. The correlations found between aluminium substitution in goethite and the soil physical properties suggest that the degree of crystallinity of this mineral influences soil properties used as soil quality indicators. Thus, goethite with a high aluminium substitution resulted in large aggregate sizes and a high porosity, and also in a low bulk density and soil penetration resistance. The presence of highly crystalline gibbsite resulted in a high density and micropore content, as well as in smaller aggregates. Interpretation of the cross-semivariogram and classification of landscape compartments in terms of the spatial dependence pattern for the relief-dependent physical and mineralogical properties of the soil proved an effective supplementary method for assessing Pearson correlations between the soil physical and mineralogical properties.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Universidade Estadual Paulista - UNESP FCAV Agronomy (Soil Science)UNESP FCAV Soils and Fertilizers DepartmentUNESP FCAV Exact Science DepartmentUniversidade Estadual Paulista - UNESP FCAV Agronomy (Soil Science)UNESP FCAV Soils and Fertilizers DepartmentUNESP FCAV Exact Science Departmen