USE OF AGROMINERAL AS SUBSTRATE FOR GROWTH OF EUCALYPTUS SEEDLINGS

Success in the production of eucalyptus seedlings directly affects the development of plants in the field. Several factors influence their initial growth, especially the substrate. This study aimed to evaluate the growth of Eucalyptus globulus seedlings and characteristics of the substrate using silicate agromineral (SA) in different proportions (substrate:SA; v/v): T0 – 100:00%, T1 – 90:10%, T2 – 80:20%, and T3 – 50:50%. The treatments were evaluated using a completely randomized design. Measurements of height (H), stem diameter (SD) and calculation of the H/SD ratio of the plants were performed every 3 weeks, totaling 4 measurements. At the end of the experiment (12 weeks), soil fertility analyses, granulometric analysis (sand, silt and clay) and total chemical analysis were carried out. Due to the chemical and mineralogical composition of SA, its use in substrate in a greater proportion (T3) promoted the increase of exchangeable K, Ca and Si contents, which influenced the increase in the sum of bases and cation exchange capacity. The levels of assimilable P and micronutrients Fe, Cu, Zn and Mn were also higher in this treatment. The increase in SA proportions in the substrate composition also favored increase in the sand fraction and reduction in the clay fraction. As for the growth of seedlings, the results were not significant for H and SD as a function of SA doses, leading to the conclusion that the solubilization and slow release of nutrients by SA did not influence the growth of the plants

The Use of Artificial Neural Network and Advanced Statistics to Model Sediment Yield on a Large Scale: Example of Morocco

Morocco ranks among countries with the greatest achievements in the field of dams in Africa but is affected by the sedimentation phenomenon due to soil erosion in upstreams. The assessment of Sediment Yield (SY) and Suspended Sediment Yield (SSY) remains a challenging global issue, especially in Morocco, characterized by a great diversity of morphological, climatic, and vegetation cover. The main objective of this paper was to perform advanced statistics and artificial neural networks (ANN) in order to understand the spatial distribution of sediment yield and the factors most controlling it, including factors of the RUSLE model (Revised Universal Soil Loss Equation). In order to produce a model able to assess SY, we collected and analyzed extensive data of most variables that can be affecting SY using 42 catchments of the biggest and important dams of Morocco. Statistical analysis of the studied watersheds shows that SY is mainly related to the watershed area and the length of the drainage network. On the other hand, the SSY is higher in watersheds where gully erosion is abundant and lower in areas with no soil horizon. The SSY is mainly related to the altitude, aridity index, sand fraction, and drainage network length. In front of the complexity of preserving this phenomenon, the ANN was applied and gave very good satisfactory results in predicting the SSY (NSE=0.93, R2=0.93).

MINERAIS PESADOS NA FRAÇÃO AREIA DO COLÚVIO-CASCALHO DIAMANTÍFERO DO GARIMPO DE PAININ (ITAITUBA, PARÁ, BRASIL)

The present work describes the heavy minerals identified in the sand fraction of the diamond-rich alluvium of the Painin garimpo, located on the right bank of the Tapajós River, in Itaituba, Pará. In general, secondary diamond deposits, such as those found in several regions of Brazil (Minas Gerais, Bahia, Goiás, etc.) have a very characteristic assemblage of heavy minerals, in which their minerals are known as diamond satellites. In Painin these minerals were extracted from the concentration of gravel obtained with the aid of a pan, after the extraction of pebbles, silt and clay fractions. The sand fraction was sieved in several fractions and from the fractions 0.25-0125 and 0.125-0.062 mm, the non-opaque heavy minerals were separated using bromoform as a heavy liquid. Minerals were identified by optical microscopy and x-ray diffraction. They stand out in descending order and according to the fraction sand, staurolite, tourmaline, corundum, rutile, diaspore, gold, topaz, zircon, anatase and kyanite. Of these, only corundum and diaspore are not classic heavy minerals from sedimentary rocks of the great Amazon region. These two minerals are together with the phosphates of the alunite supergroup, often found in the satellites of the secondary Painin diamond deposits, but not mentioned in those mentioned above, and likely to have an affinity with the primary nature of the diamond. Rutile, anatase and iron oxides are most frequently cited in these satellites. Probably corundum, diaspore and the alunite supergroup phosphates are characteristic for Painin.

Pleistocene cyclostratigraphy on the continental rise and abyssal plain of the western Ross Sea, Antarctica

<p>This thesis investigates glacimarine sedimentation processes operating on the continental margin of the western Ross Sea during the Pleistocene (˜2.5 Ma). This time period is characterised by a major global cooling step at ˜0.8 Ma, although several proposed episodes of major marine-based Antarctic Ice Sheet (AIS) retreat in warm interglacial periods are inferred to have occurred after this time. Constraining the timing and magnitude of past marine-based AIS retreat events in the Ross Sea through this time will improve our understanding of the forcing mechanisms and thresholds that drive marine-based ice sheet retreat. Identifying such mechanisms and thresholds is crucial for assisting predictive models of potential ice sheet collapse in a future world with rapidly rising atmospheric carbon dioxide (CO₂) concentrations. Six sedimentary cores forming a north-to-south transect from the continental rise to the abyssal plain of the western Ross Sea were examined in order to identify potential sedimentary signatures of past marine-based ice sheet variability and associated oceanographic change. A lithofacies scheme and stratigraphic framework were developed, which allowed the identification of shifting sedimentary processes through time. The sediments are interpreted to have been deposited primarily under the influence of bottom currents, most likely from changing rates of dense Antarctic Bottom Water (AABW) formation over glacial-interglacial cycles. Two dominant lithofacies (laminated and bioturbated) are recognised in the Pleistocene contourite sequences. Laminated facies alongside reduced ice-rafted debris (IRD) fluxes and reduced biological productivity are interpreted to represent expanded ice sheet and sea ice margins during glacial conditions, which acted to restrict surface water ventilation resulting in less oxygenated bottom waters. Conversely, laminated facies alongside reduced IRD fluxes and increased productivity are inferred to represent a reduction of ice shelf and sea ice cover resulting in enhanced AABW formation and sediment delivery. In general, it is interpreted that bioturbated facies in combination with enhanced productivity are common during interglacial conditions, with peaks in IRD associated with ice sheet retreat events leading into interglacial conditions. However, the relationships between laminated and bioturbated facies vary between sites, and facies at most sites generally alternate on timescales exceeding that of individual glacial-interglacial cycles (<100 kyr). Nonetheless, there are clear baseline shifts in the facies distributions through time across the sites, and it is inferred these represent step-like shifts in the ice sheet volume and sea ice processes on the continental shelf and above the study sites during the Pleistocene. This thesis also assesses and compares three independent methodologies of obtaining IRD mass accumulation rates (MARs). The three methodologies include counting clasts >2 mm in x-ray images, the sieved weight percentage of the medium-to-coarse sand fraction (250 µm-2 mm), and volumetric estimates of the > 125 µm sand fraction using a laser particle sizer. The x-ray and sieve methods produced comparable results, while the volumetric estimate, although showing comparable long-term trends, produces a lesser correlation to the other two methods. Spectral analysis of the IRD content and the magnetic susceptibility data series reveals that during the Early Pleistocene (2.5-1.2 Ma) ice discharge into the western Ross Sea was paced by the 41 kyr and 100 kyr cycles of obliquity and eccentricity, respectively. The Mid-Pleistocene Transition (MPT;1.2-0.8 Ma) was characterised by a switch to a higher-frequency, lower-amplitude IRD flux during a long-term period of high power in eccentricity, obliquity and precession (˜23 kyr) observed in the orbital solutions, suggesting a relatively linear response to orbital forcing at this time. The colder climate state of the Late Pleistocene (0.8-0.01 Ma) is characterised by IRD fluctuations modulated primarily by the 100 kyr eccentricity forcing that became dominant by 400 ka. In the western Ross Sea, IRD fluxes show a clear response to the orbital pacing of glacial-interglacial cycles, but are equivocal in identifying the magnitude of ice sheet loss or growth through glacial-interglacial cycles.</p>

Pleistocene cyclostratigraphy on the continental rise and abyssal plain of the western Ross Sea, Antarctica

<p>This thesis investigates glacimarine sedimentation processes operating on the continental margin of the western Ross Sea during the Pleistocene (˜2.5 Ma). This time period is characterised by a major global cooling step at ˜0.8 Ma, although several proposed episodes of major marine-based Antarctic Ice Sheet (AIS) retreat in warm interglacial periods are inferred to have occurred after this time. Constraining the timing and magnitude of past marine-based AIS retreat events in the Ross Sea through this time will improve our understanding of the forcing mechanisms and thresholds that drive marine-based ice sheet retreat. Identifying such mechanisms and thresholds is crucial for assisting predictive models of potential ice sheet collapse in a future world with rapidly rising atmospheric carbon dioxide (CO₂) concentrations. Six sedimentary cores forming a north-to-south transect from the continental rise to the abyssal plain of the western Ross Sea were examined in order to identify potential sedimentary signatures of past marine-based ice sheet variability and associated oceanographic change. A lithofacies scheme and stratigraphic framework were developed, which allowed the identification of shifting sedimentary processes through time. The sediments are interpreted to have been deposited primarily under the influence of bottom currents, most likely from changing rates of dense Antarctic Bottom Water (AABW) formation over glacial-interglacial cycles. Two dominant lithofacies (laminated and bioturbated) are recognised in the Pleistocene contourite sequences. Laminated facies alongside reduced ice-rafted debris (IRD) fluxes and reduced biological productivity are interpreted to represent expanded ice sheet and sea ice margins during glacial conditions, which acted to restrict surface water ventilation resulting in less oxygenated bottom waters. Conversely, laminated facies alongside reduced IRD fluxes and increased productivity are inferred to represent a reduction of ice shelf and sea ice cover resulting in enhanced AABW formation and sediment delivery. In general, it is interpreted that bioturbated facies in combination with enhanced productivity are common during interglacial conditions, with peaks in IRD associated with ice sheet retreat events leading into interglacial conditions. However, the relationships between laminated and bioturbated facies vary between sites, and facies at most sites generally alternate on timescales exceeding that of individual glacial-interglacial cycles (<100 kyr). Nonetheless, there are clear baseline shifts in the facies distributions through time across the sites, and it is inferred these represent step-like shifts in the ice sheet volume and sea ice processes on the continental shelf and above the study sites during the Pleistocene. This thesis also assesses and compares three independent methodologies of obtaining IRD mass accumulation rates (MARs). The three methodologies include counting clasts >2 mm in x-ray images, the sieved weight percentage of the medium-to-coarse sand fraction (250 µm-2 mm), and volumetric estimates of the > 125 µm sand fraction using a laser particle sizer. The x-ray and sieve methods produced comparable results, while the volumetric estimate, although showing comparable long-term trends, produces a lesser correlation to the other two methods. Spectral analysis of the IRD content and the magnetic susceptibility data series reveals that during the Early Pleistocene (2.5-1.2 Ma) ice discharge into the western Ross Sea was paced by the 41 kyr and 100 kyr cycles of obliquity and eccentricity, respectively. The Mid-Pleistocene Transition (MPT;1.2-0.8 Ma) was characterised by a switch to a higher-frequency, lower-amplitude IRD flux during a long-term period of high power in eccentricity, obliquity and precession (˜23 kyr) observed in the orbital solutions, suggesting a relatively linear response to orbital forcing at this time. The colder climate state of the Late Pleistocene (0.8-0.01 Ma) is characterised by IRD fluctuations modulated primarily by the 100 kyr eccentricity forcing that became dominant by 400 ka. In the western Ross Sea, IRD fluxes show a clear response to the orbital pacing of glacial-interglacial cycles, but are equivocal in identifying the magnitude of ice sheet loss or growth through glacial-interglacial cycles.</p>

A review of factors influencing performance of pervious concrete

Pervious concrete is an environment friendly solution for eliminating imperviousness-related drawbacks of conventional concrete. Pervious concrete mixes are predominantly composed of cement, coarse aggregate, and water. The partial or complete elimination of fine aggregate results in porous structure, which influences performance of pervious concrete. This article is aimed at reviewing major factors involved in the design of pervious concrete mixes, namely the compaction, aggregate to cementitious material ratio (ACR), sand fraction, water to cementitious material ratio (w/cm), size of coarse aggregate, and void ratio or porosity. The effects of various admixtures, replacement materials, and fibres, are also discussed. The results indicate that pervious concrete acts as an effective medium in promoting the sustainability of urban environments due to its multi-aspectual benefits.

How fast do submarine fans grow? Insights from the Quaternary Golo fans, offshore Corsica

High-resolution seismic, core, and chronological data from the Quaternary Golo deep-sea fans, offshore Corsica, France, give new insights into rates of submarine fan growth. Average vertical deposition rates for units that represent the Late Pleistocene glacial periods are 0.1–0.5 m/k.y. Glacial-age deposits are sand rich; in contrast, post-glacial deposits lack a significant sand fraction and are dominated by carbonate-rich mud. As a result, seismically constrained volumetric rates of deposition for glacial periods with low sea level and a subaerially exposed shelf are ~0.23 km3/k.y., 2×–5× higher than rates during interglacials when sea level is high, the shelf is submerged, and sand is trapped in shallow-marine environments. At millennial time scales, variations in deposition rate reflect climate-driven sea-level changes, autogenic avulsion of river channels that extend across the shelf during low sea level, and autogenic avulsion of submarine channels that shift the locus of deposition laterally. Short-term deposition rates range from 8.6 m/k.y. at proximal portions of submarine fans to 0.4 m/k.y. along the distal fringe. Our data show that submarine fans can be dynamic environments with formation and evolution of levee-confined channels and lobe complexes in 103–104 yr, comparable to the time scales needed to form fluvial channel belts and delta lobes.

Sediment Characterization and Monsoonal Impact on Beach Morphology at the Three Beaches along the Karachi Coast, Pakistan

Sediment characteristics plays important role in the determination and functioning of coastal ecosystems. The present study is an attempt to evaluate the variability in sediment characteristics of the three beaches: Clifton, Sandspit and Buleji, at the Karachi coast. The samples were collected during pre-monsoon and south-west monsoon seasons to evaluate the seasonal differences. The sediments of the three sites showed variations in moisture content, organic matter and grain size. The highest mean moisture (27.17%) and organic contents (3.5 %) were recorded from the sediments of Clifton. The maximum fraction of sediments (> 80 %) consist of fine to very fine sand at all studied sites. The sediments of Clifton were high in very fine sand fraction and low in coarse sand fraction as compared to Sandspit and Buleji. The sediments of all the three studied sites are moderately sorted, negatively coarse-skewed and showed leptokurtic distribution. The studied beaches of Clifton, Sandspit and Buleji shows dissimilarity in sediment characteristics as indicated through Cluster and PCA analysis. The monsoonal influence on sediment characteristics was also observed at all the three studied beaches. The strong wave action during SW monsoon season results in the deposition of the coarser sediments at the high tide level thus increasing the steepness of the beaches.

Soil mapping, classification and morphological characteristics of the University of Benin land

This study was conducted to map, and classify the soils of University of Benin Teaching, Research and Integrated Farm site. Rigid grid soil survey method at an intensive scale was done on a 62-hectare land that produced seven mapping units. In each mapping unit, a representative pedon was sunk, described and sampled. Soil samples were analyzed using standard methods. Data generated were analyzed using descriptive statistics to determine their coefficient of variation. The r esult indicated that the soils were reddish when moist at different contrasting levels. Textural classes ranged from Loamy sand to Sandy Clay Loam while structure ranged from Single grain crumb to Sub-angular blocky. The pedons were well drained except for pedon 5, which had mottles at subsurface horizon. Means of Sand fraction ranged from ≤649 to ≥ 931 gkg-1 ; Silt ranged from ≤13.2 to ≥ 47.7gkg-1 while Clay ranged from≤ 50 to ≥ 303 gkg-1 in all the pedons; clay fraction increased with increase in depth, forming argillic horizon in pedons 1,2 and 7. pH had means ranging from ≤4.23 to ≥5.28 and recorded low variation (≤ 3.6 to ≥ 13.0 %) in all the pedons. organic carbon had means ranging from ≤ 3.3 to ≥ 36.4 gkg-1; CEC ranged from ≤ 4.85 to ≥ 16.4 cmolkg-1 while Base saturation ranged from ≤16.6 to ≥ 51%. Hence pedons 1, 2 and 7 were placed in the order Ultisols ( Acrisols); pedons 3and 4 in Entisols ( Arenosols) Pedon 4; Pedons 5and 6 in Inceptisols (Cambisols) according to USDA Soil Taxonomy and correlated with WRB.

Use of Soil Physicochemical Properities in Assessment of Soil Erosion South; A Case Study of Agbor, South-South Nigeria

The study area is one of the areas in the south-south region of Nigeria that has been ravaged by erosion. This has lead loss of infrastructure and has also affected the livelihood of the inhabitant of the study area. In this study, the physiochemical properties of soils in Agbor and its neighboring communities was assessed in eleven different locations. A total of eleven soil samples, consisting of 5 samples each at a depth of 0 – 200 cm were taken in accordance with the clarification of different horizons. The samples were air-dried, crushed and sieved in 2mm mesh sieve then subjected to analysis for both physical and chemical properties in the laboratory. The physiochemical analysis results showed that pH value ranges from 5.0 to 6.3 indicating very strongly acidic to strongly acidic. Bulk density ranged from 1.29 to1.35 indicating a slight increase due to the presence of sand fraction. And low level of porosity which ranged from 49.4 to 50.9. The low obtained from Total Organic Matter (TOM) indicate intense rainfall and constant leaching. The low Ca, Mg, K+ and Na+ values indicate intense rainfall and leaching problems. The values obtained from Al3+, H+, EA and P revealed slight increase and cause of acidity nature across eleven soils test site. The properties showed by all soils revealed that they are vulnerable to weathering, leaching and easy removal by runoff. Therefore, there resistivity is low.