Intensity of Soil Pollution by Toxic Substances Depending on the Degree of Its Washout

A significant degree of ploughness of agricultural lands of Ukraine has led to increased erosion and the creation of soils of varying degrees of washout, which leads to dehumification and contamination of soils with toxic substances. Therefore, the purpose of the study was to establish the features of horizontal migration and accumulation of heavy metals of lead, cadmium, copper, and zinc, trace elements of boron and manganese, radionuclides of caesium and strontium on podzolic heavy loamy chernozems with varying degrees of washout: non-eroded, weak and medium washout, conditioned by the development of erosion processes. During the study, spectrophotometric, colorimetric, gamma-spectrometric, and radiochemical methods were used to determine the content of toxic substances in the soil. The study results showed that on slightly washed soils, the content of humus is 12.9% less, easily hydrolysed nitrogen – 13.3%, mobile forms of phosphorus – 51.1%, mobile potassium – 34.9% less than on slightly washed soils. The humus content on medium-washed soil was 8.8% less than on lightly washed soil, easily hydrolysed nitrogen – 14.3% less, mobile phosphorus – 15.3% more, mobile potassium – 42.9% more. A strong horizontal migration of mobile lead forms in washed podzolic heavy loamy chernozem was established, which increases with increasing degree of soil washout with the content of mobile lead forms on medium-washed soil by 24% more than on non-eroded soil. The same dependence was established on the content of mobile forms of zinc in the soil, with their predominance on medium-washed soil by 17 %, compared to non-washed. The content of mobile forms of copper is lower on slightly washed soil, compared to non – washed soil by 5%, boron – 18.8% less on non-washed soil, compared to medium-washed, and the content of mobile forms of manganese increases by 3.3% from slightly to medium-washed soil. It was also found that the concentration of caesium decreased by 25.6% on medium-washed soils, compared to non-washed ones

Almost half of the Pb content leaving in the bottom of the sea

Using survey data of Pb in water body from southwest of Jiaozhou Bay to west of bay mouth, in August 1992 and according to the horizontal change model and the vertical change model of matter content put forward by authors, we calculate the horizontal loss amount, vertical diluted amount and vertical sediment amount of Pb in surface and bottom layer and determine the model diagram of Pb content horizontal and vertical changes. The results showed that in August, the absolutely horizontal loss amount of Pb content in surface layer and bottom layer was 8.92μg/L, and the relatively horizontal loss amount of Pb content was 56.10%. The absolutely horizontal increase amount of Pb was 5.74μg/L in bottom layer, and the relatively horizontal increase amount was 42.23%. In the southwestern waters of the bay, the absolutely vertical diluted amount of Pb was 8.05μg/L in both surface and bottom layer, and the relatively vertical diluted amount was 50.62%. Meanwhile, in the western waters of bay mouth, Pb content in the surface and bottom layer had an absolutely vertical sediment amount of 6.61μg/L and a relatively vertical sediment amount of 48.63%. From the southwestern waters of the bay to the western waters of the bay mouth, a large amount of Pb content in the surface layer is deposited on the seabed. Therefore, during the horizontal migration of Pb content on the surface, the loss was nearly 60.00% when the current left the bay. However, Pb content in the bottom layer increased by 42.23% during its horizontal migration. Thus, the high Pb content in the surface layer is retained at the bottom of Jiaozhou Bay. When the current left the inside of the bay, Pb content in the surface layer was relatively high with the vertical diluted amount of Pb content in the surface layer and bottom layer reaching almost 50%. When the main sea current reached the western part of the bay mouth, the Pb content in the surface layer could settle on the seabed rapidly and continuously with a high sediment amount of 48.63%.

The Application of Geophysical Techniques in Tracking Leachate Plumes Migration in a Typical Cemetery within the Sandy formation in Benin City, Nigeria.

The survey aim is to track leachate plumes within the sandy formation which is below the surface laterite layer. It investigates the presence and migration of leachate plumes in the sandy region in a typical cemetery (Third Cemetery), in Benin City, Nigeria. The research engaged Vertical Electrical Sounding (VES), 2-Dimensional computation of time- lapse to detect the time rate of migration in both the vertical and horizontal directions.The field work covered a time – lapse of six months (June 2017 to December 2017). The electrical resistivity data collected in parallel equidistant lines was processed to obtain geoelectric models using Res2dinv. The leachate plumes in the cemetery migrate vertically and horizontally at different rates. The maximum and minimum rates of vertical migration are 4.1 cm/day and 0.2 cm/day respectively, while the maximum and minimum rates of horizontal migration are 32.8 cm/day and 1.7 cm/day respectively. The volumetric analysis of the plume zones indicates that of the 75,231m3 of the subsurface imaged, 6,322 m3 is the zone contaminated by leachate plume, that is, 8.4 % of the earth volume investigated contained leachate plume. The research also showed that repeated ERT surveys can track movement of leachate plume emanating from decomposed dead bodies over time in active cemetery. The average travel time for a leachate plume to transverse a vertical distance of 6.6 m in coarse sand is 366.7 days at constant migration speed of 1.8 cm/day.

Renewal and Differentiation of GCD Necklace Olfactory Sensory Neurons

Both canonical olfactory sensory neurons (OSNs) and sensory neurons belonging to the guanylate cyclase D (GCD) “necklace” subsystem are housed in the main olfactory epithelium, which is continuously bombarded by toxins, pathogens, and debris from the outside world. Canonical OSNs address this challenge, in part, by undergoing renewal through neurogenesis; however, it is not clear whether GCD OSNs also continuously regenerate and, if so, whether newborn GCD precursors follow a similar developmental trajectory to that taken by canonical OSNs. Here, we demonstrate that GCD OSNs are born throughout adulthood and can persist in the epithelium for several months. Phosphodiesterase 2A is upregulated early in the differentiation process, followed by the sequential downregulation of β-tubulin and the upregulation of CART protein. The GCD and MS4A receptors that confer sensory responses upon GCD neurons are initially expressed midway through this process but become most highly expressed once CART levels are maximal late in GCD OSN development. GCD OSN maturation is accompanied by a horizontal migration of neurons toward the central, curved portions of the cul-de-sac regions where necklace cells are concentrated. These findings demonstrate that—like their canonical counterparts—GCD OSNs undergo continuous renewal and define a GCD-specific developmental trajectory linking neurogenesis, maturation, and migration.

Demersal amphipod migrations: spatial patterns in marine shallow waters

The nocturnal displacement to the water column of species hiding in the substrate during the day (so-called demersal migration) is a widespread phenomenon in coastal habitats. However, despite the relevance of these migrations to coastal ecosystem functioning, most of their ecological aspects are poorly understood. We aim to characterize spatial distribution patterns of demersal amphipods by comparing samples collected by light traps deployed both at rocky and nearby sandy areas. Dispersal abilities of such species were explored by considering two spatial scales of separation between rocky and sandy substrates: (1) <100 m and (2) >1 km. A total of >45,000 amphipod specimens were collected in the water column during the whole study, belonging to 50 species. The numerically dominant species were Guernea coalita, Bathyporeia cf. elegans, Perioculodes longimanus and Nototropis swammerdamei. The present study highlights the relevance of substrate type and study location on coastal demersal amphipod migrations. Amphipod assemblages were significantly different in the water column above rocky and sandy bottoms, even at a small spatial scale. Species emerging from rocky bottoms tend to remain in the proximity of this habitat; they showed lower abundances in sandy areas located nearby and almost none of them reached distant sandy areas. In contrast, migrant species commonly found on sediment during the day were collected at higher abundances in light traps deployed above rocky bottoms. Although several factors (e.g. food availability, predation pressure) are proposed to explain these patterns, the purpose of this horizontal migration remains unknown.

Cd Content with an Always High Vertical Diluted Amount

Based on the investigation data about Cd in Jiaozhou Bay in August 1992 and the horizontal change model of matter content and the vertical change model of matter content proposed by the authors, the horizontal loss amount, vertical diluted amount and vertical sediment amount of Cd content in the surface and bottom layers from the southeast waters of the bay to the west waters of the bay mouth were calculated, and the model block diagram of the horizontal and vertical changes of Cd content was determined. The results show that in August, the absolutely loss amount of Cd content in the surface layer was 0.09μg/L, and the absolutely increase amount of Cd content in the bottom layer was 0.10μg/L. The relatively loss amount of Cd content in the surface layer was 12.00%, and the relatively increase amount of Cd content in the bottom layer was 41.66%. Cd content in the surface and bottom layershadabsolutely vertical diluted amount of 0.42-0.61μg/L, and its relatively vertical diluted amount was 63.63-81.33%. In August, in the horizontal migration of Cd content in the surface and bottom layers, the main sea current carried high Cd content in the surface waters.And after passing through the nearshore waters of the bay, one tenth of the Cd content in the surface layer settled to the seabed. In the horizontal migration process of Cd content in the surface layer, the loss amount of Cd content in the surface layer reached 12.00% in the nearshore waters around Jiaozhou Bay, thus the increase amount of Cd content in the bottom layer reached 41.66%. It reveals that the high Cd content in the surface layer could rapidly and continuously sink to the seabed, and the Cd content in the seabed waters in Jiaozhou Bay increased by 41.66%. In August, in the process of vertical migration, the Cd content transported by main sea current was relatively high, and the vertical diluted amount of Cd content in the surface and bottom layers was high 63.63 - 81.33% from the southeast waters of the bay to the waters in the west of the bay mouth.

Calculation of Cd Content Settlement in a Circle of Coastal Waters

With the help of the data about Cd in the southeast and southwest waters of Jiaozhou bay and models of horizontal and vertical matter content variation proposed by the authors, horizontal loss amount and vertical diluted amount of Cd content in the surface layer and bottom layer are calculated, and the model block diagrams of horizontal and vertical variation of Cd content are determined. The calculation shows that in August, the absolutely horizontal loss amount of Cd content in the surface layer and bottom layer was 0.06-0.43μg/L, and the relatively horizontal loss amount of Cd content in the surface layer and bottom layer was 42.85-57.33%. In the southeast and southwest waters of the bay, the absolutely verticaldiluted amount of Cd content in the surface layer and bottom layer was 0.24-0.61μg/L, and the relatively vertical diluted amount was 75.00-81.33%. In the process of horizontal migration in August, in the surface waters, the main sea current carried Cd content through a circle of the nearshore waters in the bay, and there was almost no source of Cd content. Therefore, in the horizontal migration process of Cd content, after a long journey, the Cd content in the surface layer and bottom layer got a lot of losses. Specifically, the absolutely horizontal loss amount was 0.06- 0.43μg/L, and the relatively horizontal loss amount was 42.85-57.33%, which proved Dongfang Yang’s migration law of matter content put forward by the authors. In the process of vertical migration in August, the Cd content transported by the main sea current was higher in the southeast waters of the bay, and the vertical diluted amount of Cd content in the surface layer and bottom layer was 81.33%. The main sea current reached the waters of the southwest bay from the waters of the southeast bay through a circle of the nearshore waters in the bay. At this time, the Cd content transported by the main sea current was relatively low in the waters of the southwest bay, but the vertical diluted amount of Cd content in the surface layer and bottom layer was still very high, which was 75.00%. It reveals that the vertical diluted amount of Cd content in the surface layer and bottom layer was very high in any water area, whether the Cd content is high or low.

How planetary growth outperforms migration

Planetary migration is a major challenge for planet-formation theories. The speed of type-I migration is proportional to the mass of a protoplanet, while the final decade of growth of a pebble-accreting planetary core takes place at a rate that scales with the mass to the two-thirds power. This results in planetary growth tracks (i.e., the evolution of the mass of a protoplanet versus its distance from the star) that become increasingly horizontal (migration dominated) with the rising mass of the protoplanet. It has been shown recently that the migration torque on a protoplanet is reduced proportional to the relative height of the gas gap carved by the growing planet. Here we show from 1D simulations of planet–disc interaction that the mass at which a planet carves a 50% gap is approximately 2.3 times the pebble isolation mass. Our measurements of the pebble isolation mass from 1D simulations match published 3D results relatively well, except at very low viscosities (α < 10−3) where the 3D pebble isolation mass is significantly higher, possibly due to gap edge instabilities that are not captured in 1D. The pebble isolation mass demarks the transition from pebble accretion to gas accretion. Gas accretion to form gas-giant planets therefore takes place over a few astronomical units of migration after reaching first the pebble isolation mass and, shortly after, the 50% gap mass. Our results demonstrate how planetary growth can outperform migration both during core accretion and during gas accretion, even when the Stokes number of the pebbles is small, St ~ 0.01, and the pebble-to-gas flux ratio in the protoplanetary disc is in the nominal range of 0.01–0.02. We find that planetary growth is very rapid in the first million years of the protoplanetary disc and that the probability for forming gas-giant planets increases with the initial size of the protoplanetary disc and with decreasing turbulent diffusion.