Database extension for digital soil mapping using artificial neural networks

Cost and time are the two most important factors conditioning soil surveys. Since these surveys provide basic information for modelling and management activities, new methods are needed to speed the soil-mapping process with limited input data. In this study, the polypedon concept was used to extend the spatial representation of sampled pedons (point data) in order to train artificial neural networks (ANNs) for digital soil mapping (DSM). The input database contained 97 soil profiles belonging to 7 different soil series and 15 digital elevation model (DEM) attributes. Pedons were represented in raster format as one-cell areas. The corresponding polypedons were then spatially represented by neighbouring raster cells (e.g. 2 × 2, … up to 6 × 6 cells). The primary database contained 97 pedons (97 cells) that were extended up to 3492 cells (in the case of 6 × 6-cell regions). This approach employed test and validation areas to calculate the respective accuracies of data interpolation and extrapolation. The results showed increased accuracies in training and interpolation (test area) but a poor level of accuracy in the extrapolation process (validation area). However, the overall precision of all predictions increased considerably. Using only topographic attributes for extrapolation was not sufficient to obtain an accurate soil map. To improve prediction, other soil-forming factors, such as landforms and/or geology, should also be considered as input data in the ANN. The proposed method could help to improve existing soil maps by using DSM results in areas with limited soil data and to save time and money in soil survey work.     

Amphipoda assemblages in a disturbed area (Alicante,Spain, Western Mediterranean)

The distribution and composition of Amphipoda assemblages were analysed off the coasts of Alicante (Spain, Western Mediterranean), a disturbed area affected by several co‐occurring anthropogenic impacts. Although differences among sampled stations were mainly related to natural parameters, anthropogenic activities were linked with changes in amphipod assemblages. Expansion of the Port of Alicante, a sewage outfall and a high salinity brine discharge could be causing the disappearance of amphipods at stations closer to these disturbances. However, the completion of port enlargement works and mitigatory dilution of the brine discharge has led to the recovery of the amphipod assemblage. Among the natural parameters, depth determines the distribution of some of the species. While Siphonoecetes sabatieri was abundant at shallow stations, Ampelisca spp., Photis longipes, Pseudolirius kroyeri, Apherusa chiereghinii and Phtisica marina were more abundant at deeper stations. Grain size and percentage of organic matter also influenced amphipod distribution, resulting in changes in species composition and in the relative percentages of different trophic groups. Species such as Ampelisca brevicornis, Perioculodes longimanus, Urothoe hesperiae and Urothoe elegans were more abundant at stations with a high content of fine sand. Carnivorous species, mainly of the Oedicerotidae family, were more abundant at those stations with a low organic matter content, while detritivorous species were more abundant at stations with a higher mud content. Among 62 identified species, three were reported for the first time from the Spanish Mediterranean coast, two species were recorded for the second time and a new species of Siphonoecetes was found, Siphonoecetes (Centraloecetes) bulborostrum. These results confirm the need for further data on amphipods from the Mediterranean Spanish coast.     

Efficiency of calcein tagging on juveniles of the sea urchins Diadema africanum and Paracentrotus lividus

We evaluated the effectiveness of chemical tagging with the fluorescent marker calcein for two key species of herbivorous sea urchins, Diadema africanum and Paracentrotus lividus, to facilitate medium‐ and long‐term ecological experiments. In total, 98 juveniles of D. africanum and 98 P. lividus were tagged with this fluorescent marker, with 12 combinations of different tagging techniques (chemical bath or injection), concentrations of calcein (2, 10 and 20 mg · l^?1), and soaking times (2, 4 and 24 h). Respective control treatments were conducted by means of seawater injection and bathing. The success of tagging was assessed after a month of feeding individuals ad libitum with the algae Dictyota sp. Sea urchins were dissected and their Aristotle's lanterns cleaned with 10% sodium hypochlorite to examine these structures under UV light using a binocular microscope. Each species was evaluated in terms of survival, percentage of tagged individuals and intensity of the resulting tag. The results showed that the method of soaking individuals of both species for 24 h in concentrations of calcein of 10 and 20 mg · l^?1 gave the highest percentage survival (100%) and the resulting tags were clearly visible.     

Animal thermal comfort index for the state of Paraíba,Brazil: trend,influencing factors,and mitigating measures

Theoretical and Applied Climatology - The present work had the objective to determine the tendency and the influence percentage of climatic variables on the Temperature and Humidity Index (THI) in...     

Predicting coffee yield based on agroclimatic data and machine learning

Theoretical and Applied Climatology - Climate directly and indirectly influences agriculture, being the main responsible for low and high yields. Prior knowledge on yield helps coffee farmers in...     

HVSR estimation of site effects in Melilla (Spain) and the damage pattern from the 01/25/2016 Mw 6.3 Alborán Sea earthquake

The January 25, 2016, Mw 6.3 Alborán Sea earthquake shook the autonomous city of Melilla (Spain) with a macro-seismic intensity of VI (EMS-98). In spite of this low intensity, significant non-structural damages were reported, whose cost was estimated in more than 13 million euros. The damages were concentrated in the modernist district, which is considered the most important and valuable part of the city. This scenario is not new in Melilla, since historical and instrumental seismicity studies based on intensities felt in Melilla have revealed that earthquakes with intensities of V–VI have a return period of approximately 25 years. However, seismic microzonation studies have not been carried out so far. In this paper, we present a seismic microzonation study based on seismic noise measurements and the foreshock, mainshock and aftershock records of the January 25, 2016, earthquake. The seismic signals were processed using the horizontal-to-vertical spectral ratio (HVSR) technique. The frequency amplification results were correlated with geological formations, and after that they were correlated with the distribution of damages. The lagoon and the recent alluvial deposits show the maximum number of damaged buildings and maximum frequency amplifications of 2–8 between 2 and 7 Hz. In the coastal deposits, some amplification in the same frequency range has been observed, but other formations show a minimum number of damaged buildings and a flat spectral response ratio. Two important factors in this damage pattern are the high vulnerability of ornamental facades characteristics (non-structural elements) of the modern architecture buildings and their location on the lagoon and the recent alluvial deposits where maximum site amplification is reached.     

Timing the tectonic mingling of ultramafic rocks and metasediments in the southern section of the coastal accretionary complex of central Chile

Uranium-lead ages are reported for zircons from ultramafic bodies and metamorphic host rocks of the Western Series that outcrop at La Cabaña, in the southern section of the coastal accretionary complex of central Chile. Metasedimentary mica schists hosting the ultramafic bodies contain a main detrital zircon population of Devonian age (365–380 Ma) clustering around ~368 Ma, differing significantly from neighbouring areas where Devonian zircons are scarce. Zircons from the metasomatic reaction zones (albitites and chloritites), formed during the emplacement and alteration of the ultramafic bodies, are mainly Ordovician (~478 Ma) and lack Devonian zircons, resembling a typical detrital zircon pattern from other locations in the Western Series. Zircons from the chloritite reaction zone of the Lavanderos serpentinite, the easternmost ultramafic body in La Cabaña, are in textural equilibrium with metamorphic ilmenite. Some of these zircons yield an average age of 283.4 ± 7 Ma (n = 6) which is identical, within error, to a previously reported K-Ar fuchsite cooling age of 282 ± 6 Ma from the reaction zone. Most zircons extracted from chromitite boulders have euhedral oscillatory-zoned growth patterns with a similar range of ages than those reported for the Western Series (324–1090 Ma; n = 12), except for two zircons with cloudy appearance and high U/Th ratios which yielded an average age of 285.5 ± 7 Ma. The presence of Early Permian zircons (~280–290 Ma) in all studied rocks suggests remobilization of Zr, possibly triggered by metasomatic fluids released during the disequilibrium reaction associated with the tectonic emplacement of the ultramafic rocks into the metasedimentary rock. Simultaneously with the formation of metasomatic zircons, Palaeozoic and Mesoproterozoic zircons from the metasedimentary rocks were mechanically incorporated into the ultramafic rocks, thus providing a record of the timing of crustal emplacement of the ultramafic rocks into the accretionary complex.     

Soil quality indicator of oxisols grown with sugarcane and native forest in northeastern São Paulo state,Brazil

The evaluation of soil quality is an important tool for degradation monitoring and sustainable management implementation. The objective of this study was to measure physical and chemical soil properties to set soil quality and validate a model of soil quality indicator in latosols (oxisols) under sugarcane cropping and native forest. The study was carried out in the cities of Araras, Santa Ernestina, and Guariba in São Paulo State, Brazil. We collected 24 samples of disturbed and undisturbed soil at 0.0–0.10 m layer from three areas grown with sugarcane and neighboring locations under native woodland. We assessed the following soil properties: (a) chemical—pH in CaCl₂, organic matter (OM), phosphorus (P), potassium (K⁺), calcium (Ca²⁺), magnesium (Mg²⁺), potential acidity (H?+?Al), aluminum (Al³⁺), and sulfur (S); (b) physical—macro- and microporosity, soil bulk density (Ds), aggregate stability, mean weight diameter (MWD), rill (K_r) and interrill (K_i) global erodibility, shear stress (τc), and magnetic susceptibility (MS). Data underwent multivariate statistics to identify the properties that denote soil quality and to set their weights within the functions of soil quality indicator (SQI). This study showed that the multivariate analysis was efficient in determining which physical and chemical properties were most sensitive, of which we can mention total sand, MS, clay, microporosity, Mg, Ca, pH, and OM. We can therefore conclude that the quality indicators of soils grown with sugarcane were lower than those under forest were, showing the need for adoption of conservation management practices.     

Ra and Rn isotopes as natural tracers of submarine groundwater discharge in the patagonian coastal zone (Argentina): an initial assessment

Submarine groundwater discharge (SGD) is herein recognized as a significant pathway of material transport from land to the coastal SW Atlantic Ocean and thus, it can be a relevant factor affecting the marine biogeochemical cycles in the region. This paper focuses on the initial measurements of ²²⁶Ra, ²²⁸Ra and ²²²Rn made in Patagonia’s coastal zone of Chubut and Santa Cruz provinces (42°S–48°S, Argentina). ²²⁶Ra activity ranged from 2.9 to 73.5 dpm 100 L^?1, and ²²⁸Ra activity ranged from 11.9 to 311.0 dpm 100 L^?1 in groundwater wells. The radium activities found in Patagonia’s marine coastal regions and adjacent shelf indicate significant enrichment throughout the coastal waters. Groundwater samples presented the largest ²²²Rn activity and ranged from 2.66 to 1083 dpm L^?1. Conversely, in the coastal marine environment, the ²²²Rn activity ranged from 1.03 to 6.23 dpm L^?1. The Patagonian coastal aquifer showed a larger enrichment in ²²⁸Ra than in ²²⁶Ra, which is a typical feature for sites where SGD is dominant, probably playing a significant role in the biogeochemistry of these coastal waters.     

Identification of hydrogeochemical processes in a volcano-sedimentary aquifer of Ciénega de Chapala in Michoacán,Mexico

The present study characterized the hydrogeochemical processes of the aquifer of Ciénega de Chapala in Michoacán, Mexico. The dominant water families contained bicarbonate magnesium and sodium. In the region, water infiltrates into a fractured volcanic environment exposed in the surrounding mountains and is transmitted to the volcano-sedimentary units of the ciénega, where silicate alteration and ion exchange processes occur in the clays of the subsoil. The Gibb diagrams confirm that the main evolutionary processes in the aquifer are rock-water interactions in the local flow and evaporation in the intermediate and regional flows. The molar ratios of HCO₃/Na and Ca/Na are congruent with the type of volcano-sedimentary environment present in the area. Ternary mixing processes associated with three end members were also identified and were related to the flow systems in the area. The local flow contributes 77% of water to the system, and the intermediate and regional flows contribute 16% and 7%, respectively.