Physical-hydraulic properties of tropical sandy-loam soil in response to rice-husk dust and cattle dung amendments and surface mulching

ABSTRACT

The effects of topsoil addition of rice-husk dust (RHD) and cattle dung (CD), alongside surface mulching with dry grasses/legume, on the infiltration characteristics and intrinsic structural properties of a deep, well-drained soil in southeastern Nigeria are assessed. Treatments are RHD-amended, CD-amended and “unamended”, each plot being either surface-mulched or left bare, with the unamended-bare plots as control. Amendments and mulch were applied at 20 t/ha equivalents. Their effects on the soil’s infiltration characteristics 7 months later were not evident; however, there was a tendency for differences: CD-amended ≥ RHD-amended ≥ unamended and surface-mulched ≥ bare-surface. By contrast, saturated hydraulic conductivity (K_s ) differed thus: CD-mulched ≥ unamended-mulched > the rest. Similar values were recorded for K_s (50.89 cm/h) and final infiltration rate (50.74 cm/h) only under CD-amended plots, which also showed the highest values (43.50 cm/h) for transmissivity of the soil. Soil penetrometer resistance was lowest in CD-amended plots (113.44 kPa) and highest in unamended plots (166.78 kPa). Topsoil addition of cattle dung and surface mulching could increase infiltration, though marginally, and permeability of coarse-textured tropical soils beyond the season of their application when their effects on soil structure have almost waned.     

The damped cable system for seismic protection of frame structures — Part II: Design and application

The complementary sections of the studies carried out on the damped cable system, whose experimental and numerical characterization and assessment analyses are described in the companion paper, are presented herein. The first section includes a criterion for a preliminary evaluation of the section area of cables, the second branch stiffness of spring‐dampers and the mutual installation preload, and suggestions for a simplified nonlinear dynamic computation of the damping coefficient of dissipaters. A second section follows, aimed at evaluating the influence of cable layout on damped cable system performance. A numerical enquiry is developed on a four‐story and an eight‐story RC plane frame, to assess their seismic response for several shapes of cables, and determine what geometrical configurations are the best performing ones. In the third section, a demonstrative application of the protective system, represented by the seismic retrofit of a hospital building with RC structure, is offered. The characteristics of the system designed for this case study, including locations, dimensions, layouts, and technical installation details of cables and spring‐dampers, are illustrated, and the improvement of seismic performance as compared with the original conditions, is finally assessed. Copyright © 2011 John Wiley & Sons, Ltd.     

Competition Between Littoral Cladocerans Macrothrix triserialis and Alona rectangula (Cladocera) in Relation to Algal Food Level and Inoculation Density

We studied the relative competitive abilities of littoral cladocerans M.triserialis and A. rectangula using green algal food at two levels (0.5 · 10⁶ and 2 · 10⁶ cells mL⁻¹ of Chlorella) under five different inoculation ratios. Both the cladoceran species were influenced by food availability and mutual competitive pressure. Macrothrix could withstand competition better under conditions of lower food availability while Alona grew better, despite competition, when more Chlorella was available. Population growth rates (r) ranged from 0.022…0.070 for Alona and from 0.024…0.075 for Macrothrix. There was a significant impact of the inoculation ratio on the maximal population density reached by either test species. Food concentration had a significant influence on the peak population density reached only for Alona rectangula. Data on the body sizes of M. triserialis and A. rectangula showed that there was a higher somatic growth with increasing food availability and decreased competitive pressure in both the test species. In Macrothrix, food concentration and the competition from Alona through different initial inoculation densities had a significant impact on the body size. At the lower food concentration, the body size was significantly smaller when the inoculation density was lowest (highest competitive pressure). The body size of Alona, on the other hand, was not affected by the competition but was significantly higher under conditions of greater food availability. These results have been discussed in light of different theories of competition.     

A cross-analysis framework for multi-source volunteered,crowdsourced, and authoritative geographic information: The case study of volunteered personal traces analysis against transport network data

Abstract

The paper discusses the need of a high-level query language to allow analysts, geographers and, in general, non-programmers to easily cross-analyze multi-source VGI created by means of apps, crowd-sourced data from social networks and authoritative geo-referenced data, usually represented as JSON data sets (nowadays, the de facto standard for data exported by social networks). Since an easy to use high-level language for querying and manipulating collections of possibly geo-tagged JSON objects is still unavailable, we propose a truly declarative language, named J-CO-QL, that is based on a well-defined execution model. A plug-in for a GIS permits to visualize geo-tagged data sets stored in a NoSQL database such as MongoDB; furthermore, the same plug-in can be used to write and execute J-CO-QL queries on those databases. The paper introduces the language by exemplifying its operators within a real study case, the aim of which is to understand the mobility of people in the neighborhood of Bergamo city. Cross-analysis of data about transportation networks and VGI from travelers is performed, by means of J-CO-QL language, capable to manipulate and transform, combine and join possibly geo-tagged JSON objects, in order to produce new possibly geo-tagged JSON objects satisfying users’ needs.     

Exact solution for granular flows

In this paper, we present the exact solution of the Riemann problem for the nonlinear one‐dimensional so‐called shallow‐water or Saint‐Venant equations with friction proposed by SAVAGE and HUTTER to describe debris avalanches. This model is based on the depth‐averaged thin layer approximation of granular flows over sloping beds and takes into account a Coulomb type friction law with a constant friction coefficient. A particular configuration of the Riemann problem corresponds to a dam of infinite length in one direction from which granular material is released from rest at a given time over an inclined rigid or erodible bed. We solve analytically and numerically the depth‐averaged long‐wave equations derived in a topography‐linked coordinate system for all the possible Riemann problems. The detailed mathematical proof of the derivation of the analytical solutions and the analysis of their structure and properties is intended, first of all, for geophysicists, mathematicians, and physicists because of the possible extension of this study to more complex problems (geometries, friction laws, …). The numerical solution of the first‐order finite‐volume method based on a Godunov‐type scheme is compared with the proposed exact Riemann problem solution. This solution is used to solve the dam‐break problem and analyze the influence of the thickness of the erodible bed on the speed of the granular front. Comparison with existing experimental results shows that, for an erodible bed, the equations lack fundamental physical significance to reproduce the observed dynamics of erosive granular flows. Copyright © 2012 John Wiley & Sons, Ltd.     

Characteristics of the burial environment related to quartz SAR-OSL dating at St. Vincent Island, NW Florida, USA

St. Vincent Island, on the northwest Gulf coast of Florida, USA, preserves a well-developed beach ridge plain that began to form 4000 years ago based on inferred ages of pottery artefact assemblages. Seven vibra cores up to 2.88 m in length (uncompacted sediment) were retrieved from six ridges across the island. The single-aliquot regenerative-dose (SAR) procedure was used to obtain two optically stimulated luminescence (OSL) ages per core at different depths within each core.

The geographically youngest ridges gave ages of 370±50–1900±300 years, yielding an inter-ridge accumulation time of 150 years assuming uniform sediment accumulation. The oldest ridge sets yielded ages of 2700±400–2800±300 years. Dating results are evaluated in terms of equivalent dose (D_E) distributions and other characteristics in relation to aspects of the burial environment, including pedogenesis.     

Water chemistry of lakes related to active and inactive Mexican volcanoes

Water chemistry of crater lakes, maars and water reservoirs linked to some Mexican volcanoes within and outside the Mexican Volcanic Belt has been determined for several years and examined regarding environmental and volcanic factors. All the analyzed lakes are relatively small with a maximum depth of 65 m, and are located in regions with different climates, from semi-arid to very humid, with altitudes ranging from 100 to more than 4000 m a.s.l. Crater lakes in active volcanoes (El Chichón, Popocatépetl) have very low pH, moderate to high temperatures and major ion concentrations varying with the level of volcanic unrest. Lakes in sub-arid and temperate-arid regions (like maars in Puebla and Guanajuato states) show high alkalinity and pH, with bicarbonate/carbonate, chloride, sodium and magnesium as predominant ions. Lakes located in humid climates (Central Michoacán and Veracruz state) have low mineralization and near-neutral pH values. In general, conservative dissolved ions and conductivity appear to be mostly controlled by precipitation/evaporation and by the ionic concentration of groundwater inputs. Calcium, magnesium, sulfate concentrations and pH are strongly influenced by volcanic-rock or volcanic gas interactions with water. The influence of low-level volcanic activity on crater lakes may be obscured by water–rock interactions, and climatic factors. One of the aims of this paper is to define the relative influence of these factors searching for a reference frame to recognize the early volcanic precursors in volcano-related lakes.     

Occurrence of PSP-producing dinoflagellate Alexandrium tamiyavanichii in Bingo-Nada, the central coastal water of the Seto Inland Sea, Hiroshima Prefecture, Japan

During surveillance of the distribution of the paralytic shellfish poison (PSP)-producing dinoflagellate in 2003, 2004 and 2005 along the coastlines of the Seto Inland Sea, Hiroshima Prefecture, Japan, some species of toxic phytoplankton were isolated from the eastern coasts, Bingo-Nada, the central regions of the Seto Inland Sea. It was rather unexpectedly revealed from the basis of the morphological characteristics that they were unambiguously identified as Alexandrium tamiyavanichii and Alexandrium catenella. Two strains (ATY041106, ATY051018) of A. tamiyavanichii showed a specific toxicity of 38.7 x 10(-6) and 111.5 x 10(-6)MU/cell, respectively. These values seemed to be several times or much higher than that of A. catenella (AC030816, AC040614), having a specific toxicity of 4.5 x 10(-6) and 4.1 x 10(-6)MU/cell, respectively, isolated in the same area. From the results of HPLC-furuorometric analysis, it revealed that the toxins in ATY041106 exist almost exclusively as beta-epimers (C2, GTX3, GTX4), which accounted for 72.7 mol%. The toxin profiles of this strain are featured by the presence of a large amount of GTX3 (59.1 mol%) and a small amount (20.6%) of C1 and 2 in comparison with the PSP compositions of A. tamarense, which is isolated as the main responsible species in Hiroshima Bay, a western part of coastal sea in Hiroshima Prefecture. On the other hand, it revealed that the toxin profiles of two strains (AC030816, AC040614) of A. catenella exist almost exclusively as beta-epimers (C2, GTX3, GTX4), which accounted for 81.8 and 56.5 mol%, as the same manner. The toxin profiles of these two strains are featured by the presence of a large amount of C2 (80.5 and 46.3 mol%) in comparison with the PSP compositions of A. tamiyavanichii. To our knowledge, this is the first record to show the distribution and harmful influence of A. tamiyavanichii and A. catenella in Bingo-Nada in Hiroshima Prefecture. Though contamination of bivalves with these PSP-producing planktons in this area has not occurred yet so far, attention should be paid to this species as well as the other causative dinoflagellate from the stand point of public health and food hygiene.