Richard Heck - Academia.edu (original) (raw)

Papers by Richard Heck

Soil Science Society of America journal, Jun 27, 2024

AGU Fall Meeting Abstracts, Dec 1, 2005

The author has further granted permission to Simon Fraser University to keep or make a digital co... more The author has further granted permission to Simon Fraser University to keep or make a digital copy for use in its circulating collection, and, without changing the content, to translate the thesislproject or extended essays, if technically possible, to any medium or format for the purpose of preservation of the digital work. The author has further agreed that permission for multiple copying of this work for scholarly purposes may be granted by either the author or the Dean of Graduate Studies. It is understood that copying or publication of this work for financial gain shall not be allowed without the author's written permission.

Revista Brasileira De Ciencia Do Solo, Dec 1, 1998

Investigações micromacromorfológicas, físicas, químicas e mineralógicas foram realizadas em solos... more Investigações micromacromorfológicas, físicas, químicas e mineralógicas foram realizadas em solos Podzólicos Amarelos na região do submédio São Francisco, município de Petrolina, estado de Pernambuco. O objetivo do estudo foi caracterizar e identificar possíveis diferenciações nos solos, em função de seus posicionamentos no terreno, pela ação conjugada dos relevos de superfície e subsuperfície, subordinadas ou não a cinco anos de manejo com irrigação em cultura de manga. Foram utilizados dados de quatro perfis de solos, sendo dois em área irrigada e dois em outra contígua que apenas tinha sido recentemente desmatada. Observou-se que os solos não foram significantemente alterados em suas características morfológicas e mineralógicas pelo manejo com irrigação. Algumas características morfológicas, como presença de fragipãs e mosqueamentos, parecem estar relacionadas com a movimentação e acumulação de água subordinadas à conjugação dos relevos de superfície e subsuperfície. Modificações nas características químicas foram observadas, principalmente relativas à alta salinidade e sodicidade, especialmente nos horizontes mais profundos dos perfis da subárea não irrigada. Tais modificações também parecem relacionadas com a dinâmica da água subordinada ao relevo. Uma vez que alguns efeitos nocivos da irrigação foram observados na área contígua, que não estava sendo utilizada, ressalta-se a necessidade de sempre extrapolar a avaliação do impacto ambiental da irrigação além dos limites das áreas dos projetos. Também foi observado que a cimentação e a impermeabilidade nos horizontes mais profundos são, provavelmente, devidas à presença de micropãs formados por argilas iluviais. Termos de indexação: salinização, sodicidade, micropãs. (1) Parte da Tese de Mestrado do primeiro autor, apresentada à Universidade Federal Rural de Pernambuco (UFRPE), para obtenção do título de Mestre em Agronomia-Ciência do Solo. Trabalho financiado pela Agência Canadense para Desenvolvimento Internacional (CIDA) e Companhia de Desenvolvimento do Vale do São Francisco (CODEVASF). Recebido para publicação em setembro de 1997 e aprovado em setembro de 1998.

Journal of Oral Science

Purpose: To assess root temperature during filling techniques and quantify the volume of endodont... more Purpose: To assess root temperature during filling techniques and quantify the volume of endodontic filling materials using infrared thermography (IT) and micro-computed tomography (micro-CT). Methods: Ninety premolars were divided into three groups: lateral condensation (LC), single cone (SC) and thermomechanical compaction (TMC). For thermal analysis, 45 teeth were assessed using a FLIR T650sc IT camera during filling techniques and 45 teeth were scanned using a Nikon micro-CT to assess gutta-percha, cement, and void volumes. Descriptive and inferential statistical analyses were performed (nonparametric Mann-Whitney test, Kruskal-Wallis test, and Friedman test with Tukey's bidirectional analysis of variance). Results: TMC showed the highest temperature increase at 15 s after the procedure and a significant temperature decrease at 45 s after its completion. TMC showed the largest volume of gutta-percha and LC the highest void volume. Conclusion: The temperature increase generated by gutta-percha endodontic filling techniques is within acceptable limits. A greater volume of endodontic cement was observed for the SL and LC filling techniques.

This paper describes the methodology applied in five basalts samples from Serra Geral Formation, ... more This paper describes the methodology applied in five basalts samples from Serra Geral Formation, Santa Catarina State, Brazil, using images obtained by X-ray computed tomography (μCT), which allow 3D visualization. The rocks samples were oriented collected and sent to the Soil Imaging Laboratory - Guelph University, in Canada, for the images acquisition and processing. The steps for the enhancement of micro-brittle structures and mineral density differences, termed in this study as anisotropic markers, consist of filters to detect edges, smoothing filters and particle analysis. The results are shown in rose diagrams for each axis (X, Y and Z) of the samples and was established the relationship between the axis and the surface fault system. In order to evaluate whether the methodology can be applied to oriented rock without the fault surface, another set of images were analyzed, based on a subvolume of the samples, without the surface fault. The results showed that the new techn...

Journal of Geography and Regional Planning, 2007

An airborne infrared image was used to produce a map of land cover types in the Eastern shore of ... more An airborne infrared image was used to produce a map of land cover types in the Eastern shore of Lake Huron, Ontario province of Canada. Maximum likelihood pixel-based and nearest neighbor object-based methods were used in this approach. Land cover classes that obtained traditional pixel-based classification approaches showed a salt-and-pepper effect having the lowest producer accuracy (59.5%). Overall classification results increased up to 80% in object- based approach but still failed to distinguish buildings and creeks. Contours and DEM thematic layers enhanced classification results to a higher level (94%) and increased the producer accuracy for buildings and creek by creating reasonable objects in segmentation process in the object-based approach. Key words: Infrared image classification, pixel-based, object-based, DEM thematic layer, land cover mapping.

Acta Scientiarum. Agronomy, 2020

In this work, lacunarity analysis is performed on soil pores segmented by the pure voxel extracti... more In this work, lacunarity analysis is performed on soil pores segmented by the pure voxel extraction method from soil tomography images. The conversion of forest to sugarcane plantation was found to result in higher sugarcane soil pore lacunarity than that of native forest soil, while the porosity was found to be lower. More precisely, this study shows that native forest has more porous soil with a more uniform spatial distribution of pores, while sugarcane soil has lower porosity and a more heterogeneous pore distribution. Moreover, validation through multivariate statistics demonstrates that lacunarity can be considered a relevant index of clustering and can explain the variability among soils under different land use systems. While porosity by itself represents a fundamental concept for quantification of the impact of land use change, the current findings demonstrate that the spatial distribution of pores also plays an important role and that pore lacunarity can be adopted as a co...

Brazilian Archives of Biology and Technology, 2019

The sandstones of the Furnas Formation in the State of Paraná, south of Brazil, are located in re... more The sandstones of the Furnas Formation in the State of Paraná, south of Brazil, are located in regions with great importance due to the natural heritage found in the rocky forms and associated flora and fauna. This paper presents a detailed analysis of the internal structure of diverse sandstones of the Furnas Formation. X-ray microtomography allowed 3D characterization of the number, pore size and shape distributions of the sandstones. Images with voxel size of 60 3 µm 3 were utilized to evaluate the sandstone's HIGHLIGHTS • Coarser sandstones presented higher porosities. • Fine sandstones had larger number of pores. • Genetic factors affected the size and shape of pores. • 3D images with voxel size of 60 3 µm 3 were evaluated.

Brazilian dental journal

The objective of this study was to evaluate the effect of root canal preparation with single-file... more The objective of this study was to evaluate the effect of root canal preparation with single-file reciprocating systems at different working lengths on the development of apical microcracks using micro-computed tomographic (micro-CT) imaging. Forty extracted human mandibular incisors were randomly assigned to 4 groups (n=10) according to the systems and working length used to prepare the root canals: Group A - WaveOne Gold at apical foramen (AF), Group B - WaveOne Gold 1 mm short of the AF (AF-1 mm), Group C - Unicone (AF) and Group D - Unicone (AF-1 mm). Micro-CT scanning was performed before and after root canal preparation at an isotropic resolution of 14 µm. Then, three examiners assessed the cross-sectional images generated to detect microcracks in the apical portion of the roots. Apical microcracks were visualized in 3, 1, 1, and 3 specimens in groups A, B, C, and D, respectively. All these microcracks observed after root canal preparation already existed prior to instrumentat...

Journal of endodontics, Jan 14, 2017

This study aimed to evaluate the ability of 2 optical coherence tomographic (OCT) systems to dete... more This study aimed to evaluate the ability of 2 optical coherence tomographic (OCT) systems to detect apical dentinal microcracks. Twenty extracted human single-rooted mandibular incisors were selected. After root canal preparation with an R40 Reciproc file (VDW, Munich, Germany), the specimens presenting apical microcracks were identified using micro-computed tomographic (micro-CT) scanning as the gold standard. Then, the apical portions of the roots were imaged with spectral domain OCT (SD-OCT) and swept-source OCT systems, and the resulting images were blindly evaluated by 3 independent examiners to detect microcracks. The diagnostic performance of each OCT device was calculated, and statistical analysis was performed. Based on the micro-CT images, 12 (60%) roots presented dentinal microcracks in the apical region. The images generated by the OCT systems were able to show microcrack lines at the same location as the corresponding micro-CT cross sections. Although the diagnostic per...

Journal of Environmental Analysis and Progress, 2016

O arranjo, orientação e organização dos grãos do solo de diferentes características são fatores d... more O arranjo, orientação e organização dos grãos do solo de diferentes características são fatores determinísticos da estrutura do solo, como também, da porosidade desse meio. A porosidade possui forte influência na aeração, na transferência de água/solutos/gases/calor, na resistência à penetração e ramificação de raízes e no desenvolvimento de microorganismos, podendo ser um elemento importante na determinação da qualidade de um solo. A avaliação morfométrica do espaço poroso de um Neossolo Regolítico Eutrófico (NRe) utilizando a Microtomografia Computadorizada de Raios-x é objetivo deste estudo, onde foram analisados os atributos físicos do solo e os tamanhos, as formas e as inclinações dos vazios intra-agregados. O NRe apresentou uma porosidade de 28% (27% de vazios inter-agregados e 1% de vazios intra-agregados) e 73% de agregados. Cerca de 73% dos vazios intra-agregados possuem volumes entre 1,278 x 10-4 a 6,545 x 10-2 mm³. Há um maior volume de vazios complexos e alongados, os qu...

Encyclopedia of Soil Science, 2008

Calcareous soils as defined here are the soils that fall between the near neutral soils and the a... more Calcareous soils as defined here are the soils that fall between the near neutral soils and the alkaline soils (Figure C1) in redox-pH space. They straddle the calcite fence of the pedogenic grid (Figure C2). The fence itself marks the pH zone below which calcite dissolves and above which it precipitates, by the reaction CaCO 3 þ H þ ¼ Ca 2þ þ HCO À 3

Revista Brasileira de Ciência do Solo, 2015

Analysis of the soil pore system represents an important way of characterizing soil structure. Pr... more Analysis of the soil pore system represents an important way of characterizing soil structure. Properties such as the shape and number of pores can be determined through soil pore evaluations. This study presents a three-dimensional (3D) characterization of the shape and number of pores of a sub-tropical soil. To do so, a second generation X-ray microtomograph equipped with a plain type detector was employed. A voltage of 120 kV and current of 80 mA was applied to the X-ray tube. The soil samples analyzed were collected at three different depths (0-10, 10-20, and 20-30 cm). The results obtained allowed qualitative (images) and quantitative (3D) analyses of the soil structure, revealing the potential of the microtomographic technique, as well as the study of differences in soil macroporosity at different depths. Macroporosity was 5.14 % in the 0-10 cm layer, 5.10 % in the 10-20 cm layer, and 6.64 % in the 20-30 cm layer. The macroporosity of unclassified pores (UN) was 0.30 % (0-10 a...

Scientia Agricola, 2008

Inadequate management of soil and irrigation water contribute to soil degradation, particularly i... more Inadequate management of soil and irrigation water contribute to soil degradation, particularly in the alluvial areas of Northeast Brazil, where salinity and sodicity are already common features. This study evaluates the effects of the addition of gypsum in the irrigation water on physical and chemical properties of soils with different levels of salinity and sodicity. Samples were collected at the Custódia irrigation area of Brazil, predominantly covered by alluvial soils. Leaching tests using simulated irrigation water classified as C3S1, and gypsum-saturated irrigation water were carried out in soil columns of 20 and 50 cm depth. Soil leaching with gypsum saturated water (T2) resulted in an increase in the amounts of exchangeable calcium and potassium, and in a decrease of soil pH, in relation to the original soil (T0), with significant statistical differences to the treatment using only water (T1). There was a reduction in the electrical conductivity, exchangeable sodium and exc...

Korean Journal of Soil …, 2010

(English) Pore network models are useful tools to investigate soil pore geometry. These models pr... more (English) Pore network models are useful tools to investigate soil pore geometry. These models provide quantitative information of pore geometry from 3D images. This study presents a pore network model to quantify pore structure and hydraulic characteristics. ...

Canadian Journal of Soil Science, 2022

Shallow soils occur throughout the world and are recognized as Leptosols at the highest level in ... more Shallow soils occur throughout the world and are recognized as Leptosols at the highest level in the World Reference Base. These soils are notionally characterized as having a lithic contact close to the soil surface. Within the Canadian System of Soil Classification (CSSC), shallow soils are currently handled at the family level according to the depth at which the lithic contact is encountered. At the series level, these soils are usually designated as a shallow phase of a non-shallow soil series, ignoring the hierarchical structure of the CSSC. Shallow soils occur almost anywhere in Canada where the glacial drift is thin. The presence of bedrock close to the surface impacts drainage, the amount of available moisture, depth for rooting, and has a major influence on soil formation. Consequently, it is proposed that the importance of shallow soils be elevated to the order level, to be consistent with the frequency of their occurrence in the Canadian landscape and for consistency with...

Geoderma, Apr 1, 2016

Abstract Soil aggregate properties, such as strength, shape and porosity, influence a range of es... more Abstract Soil aggregate properties, such as strength, shape and porosity, influence a range of essential soil functions and there is a need for more detailed understanding of the effect of soil management on these aggregate properties. There is also a need for improved knowledge on the link between aggregate and bulk soil properties. The objectives of this study were to quantify the long-term effect of rotation and tillage on aggregate shape, strength and pore characteristics, to evaluate the influence of aggregate shape and pore characteristics on aggregate strength and soil friability and to correlate aggregate properties to bulk soil properties. Soil core samples were taken in spring 2010 from the long-term rotation and tillage trial (initiated in 1980) at the University of Guelph, Canada. The rotations included were continuous corn (R1) and a diverse rotation (R6), and the tillage treatments were mouldboard ploughing (MP) and no-tillage (NT). The soil cores were exposed to a drop shatter test and air-dried before separation into different size fractions. Ten aggregates from the 4–9.2 mm size fraction per core sample (i.e. 320 in all) were X-ray micro-CT scanned. The size, shape and porosity of the aggregates were determined using image analysis with 40 μm voxel size. Subsequently, aggregate tensile strength was determined in an indirect tension test. Rotation had a more pronounced effect than tillage treatment on the different aggregate properties. The diverse rotation resulted in higher aggregate total porosity and more rounded aggregates than the continuous corn rotation. Surprisingly, there was no treatment effect on X-ray micro-CT resolvable porosities. Aggregate strength decreased with both total and X-ray micro-CT resolvable porosity even though the correlations were weak. Significant correlation was also found to aggregate sphericity although only around 10% of the variation in tensile strength could be explained by this property. Our study highlights that caution must be taken when trying to predict aggregate strength from general aggregate characteristics. For both bulk soil and aggregates, the R6-MP had highest and R1-NT lowest porosity. Tillage had strongest effect on bulk soil porosity, whereas aggregate total porosity was only affected by rotation. Our results suggest that the scale of observation is important when evaluating the influence of soil management. A strong correlation was found between aggregate strength and pore characteristics and soil fragmentation in a drop shatter test, i.e. 55% of the variation could be explained. Our study indicates therefore that bulk soil fragmentation behaviour can be predicted from aggregate characteristics. It needs to be highlighted that our results are based on one long-term experiment on a silt loam soil. The results need to be verified for soils with different soil types, climates and management histories.

Geoderma, Jul 1, 2012

Soil pore characteristics X-ray computed tomography (CT) scanning technology has, in recent decad... more Soil pore characteristics X-ray computed tomography (CT) scanning technology has, in recent decades, been shown to be a very powerful technique to visualize and quantify soil structure. The objective of this project was to quantify soil pore characteristics, on undisturbed field moist soil, using a high resolution X-ray CT scanner and link then these results to soil friability assessed using the drop shatter method. Minimally disturbed soil cores were taken from selected treatments in a long-term rotation and tillage treatment experiment located on a silt loam at the Elora Research Station near Elora, Ontario, Canada. Soil cores varied in porosity and pore characteristics. A drop shatter test was used as a reference procedure to quantify soil friability. The top 40 mm of the 80 mm high soil samples were scanned using a X-ray micro-CT scanner. The selected region of interest (36 × 36 × 36 mm) was reconstructed with a voxel size of 60 μm. Estimated surface area, produced from the drop-shatter test, varied between 0.2 and 1.62 m 2 kg − 1 , and an average of 0.79 m 2 kg − 1. Total and airfilled porosity was determined on the soil cores using traditional methods. Total porosity ranged from 41 to 60 m 3 100 m − 3 , and an average of 49 m 3 100 m − 3. The air-filled porosity, at sampling/testing, ranged between 5 and 32 m 3 100 m − 3 , with an average of 15 m 3 100 m − 3. The porosity determined from CT imagery ranged between 1 and 31 m 3 100 m − 3 , with an average of 4.5 m 3 100 m − 3. The number of branches, junctions and end points averaged 298, 117 and 198 per cm 3 , respectively. We found significant and strong correlations between the soil pore characteristics assessed on the whole soil cores and the characteristics of the air-filled pores determined using high-resolution X-ray computer tomography (CT). Our study confirmed a significant correlation between soil friability, expressed by surface area produced by standardized dropshatter, and soil pore characteristics. The strongest correlations were found with porosity, surface area and number of junctions per cm 3 .

Soil & Tillage Research, Mar 1, 2013

Tillage and rotation are fundamental factors influencing soil quality and thus the sustainability... more Tillage and rotation are fundamental factors influencing soil quality and thus the sustainability of cropping systems. Many studies have focused on the effects of either tillage or rotation, but few have quantified the long term integrated effects of both. We studied the issue using a 30-year old long-term rotation and tillage treatment experiment on a Canadian silt loam soil. Topsoil measurements were carried out for three different rotations: R1 (C-CC -C) continuous corn (Zea mays L.), R6. (C-C-O(RC), B(RC)) corn, corn, oats (Avena fatua L.) and spring barley (Hordeum vulgare L.) and R8, (C-C-S-S) corn, corn, soybean (Glycine max L.), soybean. A red clover (Trifolium pretense L.) cover crop was under seeded in oats and spring barley in R6. In 2010, first year corn was grown in R6 and R8. The tillage treatments included no tillage, NT and mouldboard ploughing, MP. Topsoil structural quality was visually evaluated in early June and mid October. Minimal disturbed soil cores collected in early June were used for X-ray CT scanning and to quantify water content and porosity. Soil friability was determined on the soil samples using a drop shatter test. Crop yield was determined and correlated to the soil quality estimates. We found significant effect of both rotation and tillage on visual soil structure at both times of assessment. Poor soil structure was found for NT except when combined with a diverse crop rotation (R6). The soil core pore characteristics data also displayed a significant effect of tillage but only a weak insignificant effect of rotation. The drop shatter results were in accordance with the visual assessment data. Crop yield correlated significantly with the visual soil structure scores. We conclude that a diverse crop rotation was needed for an optimal performance of NT for the studied soil.