Degree Of Erosion Research Articles

Is bipolar hemiarthroplasty an appropriate type of hip articulation following proximal femoral or total femoral resections for musculoskeletal malignancies?

Different approaches are applied for reconstruction in patients with a musculoskeletal malignancy which require a proximal femoral or total femoral resection. We aimed to evaluate the treatment outcomes of patients who underwent a proximal femoral or total femoral resection due to bone and soft tissue tumors and had an endoprosthetic reconstruction by a bipolar hemiarthroplasty type of hip articulation. We retrospectively identified 133 patients who underwent a proximal femoral or total femoral endoprosthetic replacement after resection of a bone or soft tissue malignancy. There were 74 male and 59 female patients, with a mean age of 55.02 ± 16.92years (range 11-84years) and a median follow-up of 24.47 ± 24.45months (range 6-164months). Patient demographics, surgical, and oncological data were recorded. Acetabular wear was measured using the classification proposed by Baker. Functional assessment was performed using the Musculoskeletal Tumor Society (MSTS) functional score. There was no statistically significant difference among primary diagnostic groups in terms of gender, prosthesis type, trochanter major resection, local recurrence, complication/revision rate, and MSTS Score (p > 0.05, for each parameter). On the other hand, a statistically significant difference was detected in terms of degree of acetabular erosion among diagnostic groups (p < 0.001); the acetabular erosion rate (AER) was found to be lower in patients with metastatic carcinoma than in patients with a diagnosis of primary bone or soft tissue sarcoma. The univariable analysis revealed that the effect of age, primary diagnosis, localization, follow-up time, and presence and number of distant organ metastasis variables on AER were found to be statistically significant (p = 0.018, p = 0.035, p = 0.002, p = 0.007, p = 0.031, p = 0.040, respectively). In patients who undergo a proximal femoral or a total femoral resection due to a musculoskeletal tumor, bipolar hemiarthroplasty is an adequate type of hip articulation method, since it does not affect the revision requirements and functional outcomes of patients with acetabular erosion.

Effect of a Cytoprotective Dose of Dehydroleucodine, Xanthatin, and 3-Benzyloxymethyl-5H-furan-2-one on Gastric Mucosal Lesions Induced by Mast Cell Activation.

The aim of this study was to determine whether the lactones dehydroleucodine, xanthatin and 3-benzyloxymethyl-5H-furan-2-one, would be effective in an animal model of gastric ulcer induced by mast cell activation. Rats were divided into ten groups. Treatments were repeated for four days. The degree of gastric erosion was assessed with a scoring system and histological preparations. Gastric mast cell morphology was analyzed by histological procedures. Serum serotonin levels were determined as markers of mast cell activation. Statistical analyses were done using ANOVA and Tukey–Kramer test. We demonstrated that the repeated administration of compound 48/80 results in extensive mucosal lesions in the gastric mucosa and that such lesions occurred in association with mast cell degranulation and a significant increase of serum serotonin. We showed that these lesions were prevented by dehydroleucodine, xanthatin, and 3-benzyloxymethyl-5H-furan-2-one and that this effect was similar to that obtained with sodium cromoglycate. In conclusion, the results of the present study indicate that the optimal gastric cytoprotective dose of dehydroleucodine, xanthatin, and 3-benzyloxymethyl-5H-furan-2-one is efficacious in an animal model of gastric ulcer induced by mast cell activation. Our findings suggest that these lactones could be valuable tools for designing novel therapeutic agents for digestive disorders associated with inappropriate mast cell activation.

Tectonic and magmatic factors of Li-F granites localization of the East of Russia

We have investigated tectonic and magmatic factors of Li-F granites localization of the East of Russia. The study is based on the ideas of Far Eastern geologists about the deep structures of intraplate activity. A model of a source structure with mantle heat sources and ore-forming magmatic complexes was used. We carried out a special metallogenic analysis of the East of Russia as applied to the rare metal-tin-bearing formation of subalkaline leucogranites, including Li-F ones.&#x0D; Source structures are the main factor in the tectonic and magmatic development of the East of Russia, localization of ore-forming granites and the formation of rare-metal-tin ore regions. On deep layers of source structures there are areas of the mantle and earth's crust decompaction, heat, magmas and fluids sources, as well as granitoid cryptobatholiths. Relatively large massifs of leucogranites, small intrusions of tin monzonitoids and Li-F granites are concentrated near the modern surface. The source structures correspond to the rank of the ore region. The source structures in the South of the region are: Badzhalskaya, Miao-Chanskaya, Ippato-Merekskaya, Hogdu-Lianchlinskaya, Arminskaya, etc.; in the North: Pevekskaya, Kuiviveem-Pyrkakayskaya, Kuekvun-Ekiatapskaya, Iultinskaya, Telekayskaya, Central Polousnaya, Omsukchanskaya, etc. Three types of ore regions have been identified according to the degree of source structures and Li-F granites erosion.&#x0D; We have also outlined the patterns of source structures evolution and their place in the geological history of ore-bearing granites. A classification of source structures and its comparison with the classifications of regional intrusives and metallogenic subdivisions are proposed. It has been established that, despite the diversity of tectonic, geological and petrological settings in the East of Russia, the intrusions of Li-F granites are regulated by the same tectonic and magmatic factors. The tectonic and magmatic factors of Li-F granites localization in the East of Russia are identified and classified as geophysical, orogenic, geoblock, magmatic, metasomatic and disjunctive.

Numerical simulation of the cathode erosion by ion sputtering in hollow cathode arc discharges

Cathode erosion by ion sputtering is one of the primary erosion mechanisms in hollow cathode discharges. In this paper, the moving mesh approach coupling with a two-dimensional plasma fluid model was employed to simulate the cathode erosion process for 100 h in a hollow cathode arc discharge. In the numerical model, plasma transport, arc flow and heating, and cathode thermal balance were considered. In addition, the electron emission, ion bombardment, and surface radiation were taken into account on the cathode wall. The normal erosion depth on the cathode surface was defined to characterize the degree of cathode erosion. The results showed that the ion sputtering erosion was sensitive to the ion flux toward the cathode wall and the distribution of the plasma potential. The external magnetic field could mitigate the erosion process. The changes of erosion depth and position under different discharge currents, gas flow rates, and intensities of the applied magnetic field were also investigated in this paper.

Detection of areas prone to wind erosion and air pollution using DSI and PDSI indices

Many significant dust storms have occurred in the Central part of Iran since ancient times. Recently, the frequency and intensity of such events have increased remarkably, especially in hyper-arid and arid zones of Yazd province. Under these conditions, it is necessary to address several notable challenges, including methods of detecting the potential sites for wind erosion and dust storms and degree of success in reducing air pollution and dust storms. Thus, this study utilized weather codes of dust to monitor wind erosion and dust storm frequency in Yazd province, Iran. The study also defined a new appropriate index to evaluate air pollution in terms of different dust events. A new dust storm index for air pollution (PDSI) introduces to monitor air pollution. Daily dust storm index (DSI) is another empirical model to study dust storm activities. Weather codes associated with dust events were used at 11 synoptic stations in the Yazd province during 2000–2017. PDSI assessment using meteorological code 06 and hourly scale is used as the main tools for evaluating air pollution. Evaluation of dust weather codes using different weights performed to properly analyze wind erosion and air pollution status at different spatial and temporal scales. Yazd station had the highest amount of air pollution (105.9). Meybod had the highest amount of wind erosion (9.76) with a significant potential to occur dust storm. Assessment of the DSI and PDSI indicates a significant increase (about ten times) in wind erosion and air pollution in recent years. Poor land management and the existence of outdoor dust haze are the main causes of the terrible increase in air pollution during 2008–2017. It is recommended to promote sustainable industrial development and reduce the negative impacts of mining activities in regions with medium to severe air pollution.

A review of road infrastructure development and contemporary degradation on K’gari-Fraser Island

ABSTRACT Unpaved roads are often of poor quality in parks globally, particularly where funding and resources are limited. We review the history of road infrastructure development and provide contemporary evidence of road degradation on World Heritage listed K’gari-Fraser Island to demonstrate a need for a more sustainable transport system. Historical industry from mining and timber exploitation has established but also deeply impacted many sections of the island’s roads. Contemporary observations reveal high volumes of vehicular traffic contributing to erosion and deep-cuttings on many sections of this international tourist destination that attracts approximately 450,000 visitors per annum. Current observations of road degradation show that a more sustainable transport system should be implemented to mitigate further erosion from vehicular and weather impacts. The article provides justification for the need for sustainable transport solutions and strategies based on a history of inland sand road degradation and erosion leading to environmental impacts on K’gari-Fraser Island. Photographic evidence of varying degrees of degradation and erosion currently occurring and from past industry on K’gari’s roads is provided in this article to strengthen the argument for a more sustainable transport network.

Watershed Prioritization Based on Morphometric Parameters and PCA Technique: A Case Study of Deonar River Sub Basin, Sidhi Area, Madhya Pradesh, India

Abstract Watershed prioritization is beneficial for soil, groundwater development as well as for the implementation of the artificial recharge schemes. It is a well-known scientific process of drainage network delineation and ranking of different sub-watersheds of a basin. This is the mostly adopted morphometric interpretation and assessment technique and used for prioritization of watershed. In the present study, morphometric analysis of the Deonar river sub basin has been carried out to interpret and assess its hydrological importance. The study was carried out using geospatial approach and it is reflected in morphometric parameters such as linear, areal and relief aspects of the watershed. Detailed morphometric analysis and drainage map has been prepared from ASTER DEM (digital elevation model) having 30m spatial resolution using GIS environment. The delineated and analysed morphometric parameters are helpful for planning of soil and water conservation with the PCA approach. Principal component analysis (PCA) is a well-known technique that reduces the dimensionality of the given input data set which maximizes the amount of variance information. The delineated drainage order comes 1 to 5 and the watershed comprises of 6 sub-watersheds named as SW-I to SW-VI were analyzed. Based on Deonar river sub basin morphometric analysis, the sub-watershed is categorised into three classes as high, medium and low priority zones. Watershed prioritization and correlation of morphometric parameters of the Deonar river basin illustrates and indicates the high priority due to the greater degree of erosion. The analysed result is useful for making better planning and management, to identify the artificial recharge structures of the various sub-watersheds for improving the water potentiality.

A Comparative Analysis of Soil Loss Tolerance and Productivity of the Olive Groves in the Protected Designation of Origin (PDO) Areas Norte Alentejano (Portugal) and Estepa (Andalusia, Spain)

Olive groves are Mediterranean systems that occupy more than 2.5 M ha in Spain and 0.352 M ha in Portugal. Assuming the differences between both countries in terms of olive grove regulation and considering their multifunctionality, it is useful to implement agronomic indices to estimate their sustainability. The Soil Loss Tolerance Index (SLTI) and the Soil Productivity Index (SPI) are two such indices. We calculated both indices in the Protected Designation of Origin (PDO) Norte Alentejano (Portugal). The SLTI index was adapted considering specific variables of the analysed olive groves (i.e., SLTIog). The values obtained were compared with those previously estimated for PDO Estepa (Spain). The negative impacts of erosion and the underlying agricultural practices on the sustainability of olive groves became evident, resulting in decreased soil productivity at the regional level. The SLTIog index showed higher values for crops, being a more realistic tool to analyse sustainability. A higher soil loss tolerance was detected for integrated groves in the PDO Norte Alentejano than for PDO Estepa due to the shorter age of olive cultivation in Portugal, with incipient soil impacts. These indices provide information on the degree of soil erosion, allowing farmers and decision-makers to apply practices to maximise the sustainability of olive groves.

4-Phenylbutyric acid, a potent endoplasmic reticulum stress inhibitor, attenuates the severity of collagen-induced arthritis in mice via inhibition of proliferation and inflammatory responses of synovial fibroblasts.

4-Phenylbutyric acid (4-PBA) exerts potent pharmacological effects, including anti-inflammatory properties, via inhibition of endoplasmic reticulum (ER) stress. However, it is not known whether 4-PBA attenuates the severity of rheumatoid arthritis. The present study aimed to determine whether the inhibition of ER stress by 4-PBA ameliorated experimentally induced arthritis. The proliferation of synovial fibroblasts (SFs) and expression of matrix metalloproteinases (MMPs) were evaluated in the presence of interleukin (IL)-1β with or without 4-PBA. The effect of 4-PBA on the phosphorylation of Mitogen-activated protein kinase (MAPK) and the activation of Nuclear factor-κB (NF-κB) in IL-1β-stimulated SFs was assessed. In an in vivo study, the effects of 4-PBA were investigated using DBA/1 mice with collagen-induced arthritis (CIA). Clinical, histological, and serological assessments of CIA treated with 4-PBA were performed to determine the therapeutic effect of 4-PBA. In vitro, 4-PBA inhibited the proliferation and expression of IL-1β-stimulated SFs and MMP-1 and MMP-3 through the suppression of both the phosphorylation of MAPKs and NF-κB in IL-1β-stimulated SFs. The 4-PBA treatment markedly attenuated the severity of arthritis in CIA mice. The 4-PBA treatment ameliorated joint swelling and the degree of bone erosion and destruction and decreased the level of inflammatory cytokines and MMP-3 and Cox-2. Furthermore, remarkable improvements in histopathological findings occurred in 4-PBA-treated mice. These findings suggested that 4-PBA could attenuate the severity of arthritis in CIA mice by partially blocking the phosphorylation of MAPKs and the activation of NF-κB in SFs. Thus, through the inhibition of ER stress, 4-PBA may be a potent agent for the treatment of RA.

Agricultural soil loss

Soil Conservation The current era of major loss of agriculturally productive soils has gained relatively little public attention. It seems intuitively unnecessary to spell out what will happen to food production, hydrology, carbon sequestration, and ecological services if we allow soil erosion to proceed at current rates. However, it is difficult to quantify soil loss and to translate that into agricultural loss. Thaler et al. focused on the US Corn Belt and used remote sensing to map areas in fields that have no carbon-rich (i.e., A-horizon) soils remaining. Previous attempts to quantify soil loss suggested that little damage had occurred. By contrast, the new estimate indicates that ∼35% of an area of ∼400,000 square kilometers (a third of the Corn Belt area) has lost its A-horizon soil (∼1.4 petagrams), especially on hillslopes. The authors suggest that mechanically working the land (tillage) has been responsible for most soil loss in this region. This degree of erosion translates into a 6% reduction in overall crop yield and ∼$3 billion in economic loss. Proc. Natl. Acad. Sci. U.S.A. 118 , e1922375118 (2021).

Biodiversity of AM Fungi in Coffee Cultivated on Eroded Soil

Arbuscular mycorrhizal fungi (AMFs) play an important role in soil improvement, leading to the enhanced growth and yield of the host plants. The diversity, abundance, and richness of AMFs were evaluated in eight coffee plantations (Coffea arabica L.) with different erosion degrees. The results indicated that 26 AMFs morphotypes scattered across four genera were recovered and included five species. Funneliformis species were the most dominant representatives of the total isolates followed by Claroideoglomus, Rhizoglomus, Gigaspora, Acaulospora, Glomus, Diversispora, Septoglomus, and Scutellospora. The highest diversity and richness were found in non-eroded agroecosystems, followed by sites with a minimum erosion, and the lowest values were reported within the highly eroded agroecosystems. These results suggest that eroded soil affects AMF fungi, creating the need to carry out studies that allow for the implementation of cultural practices where biodiversity and soil are preserved.

The collapse of a granular column onto an erodible bed: dynamics and morphology scaling

The collapse of a granular column onto an erodible bed is studied experimentally and numerically, and underlying scaling laws on deposition morphology and erosion geometry are mainly considered. The differences in material properties between the column and the erodible bed give rise to the change in flow behaviors, in which the particle density ratio between the column and the erodible bed plays a crucial role. The flow duration apparently increases with initial aspect ratio $$a$$ , but its normalized value tends to a constant at large $$a$$ regardless of particle density ratio. Furthermore, several univariable scaling laws are put forward to quantitatively characterize final deposition morphology and erosion geometry. By rescaling these univariable functions, the generalized scaling laws containing two relevant variables are further proposed, which have been verified to be applicable for a wider range of situations where the degree of erosion dominates the propagation of collapsing flow.

Coupling loss characteristics of N-P-C through runoff and sediment in the hilly region of SE China under simulated rainfall.

Soil total carbon (TC), phosphorus (P), and nitrogen (N) exports from the weathered granite slopes are greatly influenced by the complex hydrological processes and terrain factors. In this study, the coupling loss characteristics of N-P-C via runoff and sediment were studied with two soil tanks under simulated rainfalls. Three soils respectively derived from the tillage layer (T-soil), laterite layer (L-soil), and sand layer (S-soil) were employed to determine the interactions of hydrology and topography on N-P-C exports under three rainfall intensities (1.5, 2.0, and 2.5 mm/min). The erosion degree of different soils displayed an order of S-soil > L-soil > T-soil. The results showed that surface flow was the main runoff form for L- and T-soil, while underground flow was predominant for S-soil. There was a linear correlation between sediment and surface flow (R2 > 0.78). Surface flow was the dominant pathway of P loss via runoff with underground flow being an important supplementation, and the main P loss pattern switched between dissolved phosphorus (DP) and particle phosphorus (PP) during the experiment. However, P lost via eroded sediment accounted for more than 94% of the TP loss amount. N presented an opposite trend to P and was mainly lost via underground flow. The main N loss form in surface and underground flow was NO3--N. Underground flow was the predominant total nitrogen (TN) loss pathway for S- and L-soil, followed by sediment and surface flow. For T-soil, TN lost via runoff was much greater than that carried by eroded sediment. TC for S-soil was mainly lost via underground flow while that for L- and T-soil was mostly lost via surface flow. Both N-P loss loads in surface flow and P loss load in underground flow were positively correlated with TC loss load (p < 0.05), indicating that the presence of organic matter brings about more nutrient losses. These results expand our understanding of the combined effects of rainfall intensity and erosion degree on runoff and sediment yields as well as N-P-C losses from the bare weathered granite slopes of SE China.

Temporal and Spatial Distribution of Surface Sediment and Its Implications in the Yangtze Subaqueous Delta

Characteristics of sediments vary significantly temporally and spatially in the Yangtze subaqueous delta and adjacent East China Sea shelf due to complicated dynamic conditions. Magnetic properties of sediments are sensitive to hydrodynamics and provenance, and therefore can indicate sediment transportation and deposition. High-resolution surface sediments collected in different seasons and years from the Yangtze subaqueous delta and neighboring East China Sea shelf were subjected to environmental magnetic analyses. In combination with granulometric analysis, this paper discusses temporal and spatial variations of magnetic properties and their implications for indicating sediment transportation, sediment source identification, and hydrodynamic response. The results show that magnetic parameters SIRM and XARM/SIRM suggest sediment transportation path from the Yangtze River into the East China Sea, with majority migrating to the south and southeast and then deposited to the west of 123°E, while a little fine sediment delivered to the northeast in summer. Cluster analysis demonstrates three sedimentation districts according to magnetic properties and particle size in the study area, which represent modern Yangtze sediment, late Pleistocene relict sand, and their mixture, respectively. Temporal-spatial changes in particle size of sediments suggests erosion outside the North Branch in the past few years, while opposite trend of changes on particle size of surface sediment in the adjacent area might reflect different degrees of erosion.

Rock Slope Stability Assessment Along Rawanduz Main Road, Kurdistan Region

The rock slope instability along the Khalifan-Bekhal-Rawanduz main road has been studied in the southwestern limb of the Bradost anticline (Mountain) and both northeastern and southwestern limb of the Korek anticline (Mountain) in the northeast of the Erbil city, Kurdistan Region, Iraq. The major factors of the instability of the rock slopes in the study area are types of discontinuous and the degree of erosion. Ten stations have been chosen for fieldwork. The expected failure types that may occur along the road are plane sliding and wedge sliding. This research is mainly focused on the type of failure along the rock slope and the factor that affect the instability of the studied slopes and have found that they are slope orientation and geometry of the discontinuity. Different remediation methods are proposed for the studied rock slopes base on rock slope analysis. The rock slopes along the road require continuous monitoring because of their hazard conditions.

Influence of mechanical faults on electrical resistance in high voltage circuit breaker

The health of contact sets is one of the most critical factors for the breaking capacity of the high voltage circuit breaker. Dynamic resistance measurement is considered to be an effective method to assess the erosion degree of the contact sets. However, the electrical resistance may be influenced by many other mechanical faults which will cause the misdiagnosis of the contact sets. At present, the influence mechanism has not been clarified. Therefore, the influence mechanism and degree of mechanical faults (stress relaxation, fatigue, friction) of contact sets is studied in the present paper. Firstly, the accelerated stress relaxation experiments of CuW alloy, the fatigue experiments of contact sets, and the mechanical friction experiments are carried out to obtain the relationship between the fault degree and the electrical resistance. Secondly, the fatigue fracture, micromorphology, energy dispersive spectroscopy, and metal loss of the contact sets are investigated. Thirdly, the stress distribution and fatigue fracture of the contact finger is analyzed by the finite element method. Based on the above works, the fatigue damage, and the partial loss of the contact fingers are considered to be the most distinct influence on the electrical resistance curves.

Ultrasound-assisted sequentially precipitated nickel-silica catalysts and its application in the partial hydrogenation of edible oil

Sequentially precipitated Mg-promoted nickel-silica catalysts with ageing performed under various ultrasonic intensities were employed to study the catalyst performance in the partial hydrogenation of sunflower oil. Results from various characterisation studies showed that increasing ultrasonic intensity caused a higher degree of hydroxycarbonate erosion and suppressed the formation of Ni silicates and silica support, which improved Ni dispersion, BET surface area and catalyst reducibility. Growth of silica clusters on the catalyst aggregates were observed in the absence of ultrasonication, which explained the higher silica and nickel silicate content on the outer surface of the catalyst particle. Application of ultrasound also altered the electron density of the Ni species, which led to higher activity and enhanced product selectivity for sonicated catalysts. The catalyst synthesised with ultrasonic intensity of 20.78 Wcm−2 achieved 22.6% increase in hydrogenation activity, along with 28.5% decrease in trans-C18:1 yield at IV = 70, thus supporting the feasibility of such technique.

The Origin of Terraces in Buried Valleys in the Northwest of the East European Plain

Abstract —The paper considers the origin of terraces that often complicate the slopes of abnormally deep buried valleys in the northwest of the East European Plain. The Izborsk–Maly valley (Pskov Region, Russia), which is half filled with Quaternary sediments, was chosen as the object of study. Since the upper part of the valley remains unfilled, it is possible to study in detail both geologic and geomorphologic structures of its terraced slopes being of particular interest in the context of the origin of buried valleys and the role of substrate in it. The four denudation-terrace levels that have been identified on the slopes of the Izborsk–Maly valley at absolute elevations of 53, 56–58, 70–72, and 75–77 m formed during the destruction of the preglacial karst landscape under the influence of Pleistocene glaciations. The formation of the terraces was probably linked with several stages of overdeepening of the valley and its expansion by the glacial erosion processes, which corresponded to at least two stages of the ice sheet advance in this area. The last stage may have been the beginning of the Late Valdai (Weichselian) glaciation or the activation of the edge of an ice sheet during its Luga phase (~15.7 cal kyr BP). Results of the study suggest that the Izborsk–Maly valley formed in subglacial conditions. The degree of glacial erosion was determined primarily by the coherence of Devonian carbonate-terrigenous rocks hosting the valley and the degree of the area transformation by karst processes. The cirque shape of slopes is the evidence of karst processes expression in pre-glacial time. Analysis of literature data shows that the origin of denudation terraces in the buried valleys in the northwest of the East European Plain has been paid little attention. The obtained data contribute to the study of this problem and provide insights into the origin of buried valleys.

Estimation of erodization of the irrigated soil cover in the Priazov zone

The article considers the assessment of the degree of eroded irrigated soil cover based on field studies conducted in 2018 and 2020 in the Kuibyshev district of the Rostov region. Analysis and evaluation of diagnostic indicators of erosion processes was carried out in 12 point samples from the 0-20 cm soil layer. The main diagnostic indicators of the studied area are: humus content; mobile phosphorus and exchange potassium. A comparative assessment of the degree of site erosion is presented. It is noted that in 2018 there are medium-eroded areas (the area where the wells are located 2, 3, 8, 9, 11, 12), and in 2020, uneroded and slightly eroded soils are already observed on the site, which indicates that agro-reclamation measures are being taken to prevent negative processes. In 2018, the highest humus content was observed in well 6 (130.78 t/ha), and the lowest-in well 11 (85.54 t/ha). The lowest humus content for 2020 was found in well 8 (78.78 t/ha), the highest-in well 12 (91.78 t/ha), which corresponds to 2 and 1 degrees of erosion. In 2018 the availability of mobile phosphorus in the surveyed area is high, with the exception of sampling points 8 (22.29 mg / kg), 9 (15.71 mg/kg) and 12 (19.15 mg/kg), which corresponds to the degree of soil cover erosion from 0 to 3. The lowest values of exchange potassium are observed in 2018, which is typical for leaching of the main nutrients during irrigation. Further monitoring studies of the soil cover should be carried out systematically to assess the degree of erosion hazard during irrigation, which will serve as a basis for developing models and forecasts of changes in soil fertility.

Pleistocene Ophiomorpha nodosa from Buenos Aires, Argentina: Paleoenvironmental implications for ghost shrimp trace fossils along South America

Ophiomorpha nodosa Lundgren1891 is described from Puente de Pascua Formation Late Pleistocene of northeastern Buenos Aires province. The pelletal morphology and the base of ramifications of O. nodosa burrows are compared with mid-Holocene, Late Pleistocene Pehuen-Có locality and southern Brazil records. The preservation between sites differs in the degree of erosion and weathering, in situ or ex situ provenance, fragmentary shafts with or without branching and degree of cementation. These comparisons between sites suggest that different environmental conditions have generated the accumulation of trace fossils in transgressive and highstand depositional environments from foreshore through offshore. Neoichnological observations ascribe the burrowing of Ophiomorpha to ghost shrimps. For South American records Audacallichirus (formerly Sergio) mirim Rodrigues and Hödl, 1990 has been suggested as the producer, due to the similarity in morphology between modern and fossil burrows, and geographic distribution of ghost-shrimps. Finding of a widespread ichnotaxon possibly produced by the same taxon in different environmental conditions in the southwestern Atlantic suggests behavioral plasticity. The paleoenvironment of Puente de Pascua Formation in the level with Ophiomorpha burrows is interpreted a tidal flat in intertidal to subtidal depositional environments and relatively calm waters.