Vertical Sinking Research Articles

Indirect Impact of Eutrophication on Occurrence, Air-Water Exchange, and Vertical Sinking Fluxes of Antibiotics in a Subtropical River.

A significant challenge that warrants attention is the influence of eutrophication on the biogeochemical cycle of emerging contaminants (ECs) in aquatic environments. Antibiotics pollution in the eutrophic Pearl River in South China was examined to offer new insights into the effects of eutrophication on the occurrence, air-water exchange fluxes (Fair-water), and vertical sinking fluxes (Fsinking) of antibiotics. Antibiotics transferred to the atmosphere primarily through aerosolization controlled by phytoplankton biomass and significant spatiotemporal variations were observed in the Fair-water of individual antibiotics throughout all sites and seasons. The Fsinking of ∑AB14 (defined as a summary of 14 antibiotics) was 750.46 ± 283.19, 242.71 ± 122.87, and 346.74 ± 249.52 ng of m-2 d-1 in spring, summer, and winter seasons. Eutrophication indirectly led to an elevated pH, which reduced seasonal Fair-water of antibiotics, sediment aromaticity, and phytoplankton hydrophobicity, thereby decreasing antibiotic accumulation in sediments and phytoplankton. Negative correlations were further found between Fsinking and the water column daily loss of antibiotics with phytoplankton biomass. The novelty of this study is to provide new complementary knowledge for the regulation mechanisms of antibiotics by phytoplankton biological pump, offering novel perspectives and approaches to understanding the coupling between eutrophication and migration and fate of antibiotics in a subtropical eutrophic river.

Unveiling the Global Extent of Land Subsidence: The Sinking Crisis

AbstractLand subsidence, referring to the vertical sinking of land surface, is a significant geohazard posing serious risks to security of infrastructure, natural resources, built environment, and businesses in numerous places worldwide. Using deep learning approaches combined with more than 46,000 subsidence data, we predicted global land subsidence based on 23 environmental parameters. The generated global map of land subsidence covers historically documented and new subsiding areas. We estimate that more than 6.3 million square kilometers of the global land is influenced by significant subsidence rates. That includes 231,000 square kilometers of urban and dense settlement areas and a population of nearly 2 billion. The model revealed a positive correlation between the intensity of groundwater abstraction and the subsidence rate. Our results offer new insights regarding potential hotspots of land subsidence and provide the information required to devise necessary action plans and develop effective policies to mitigate this growing challenge worldwide.

Contribution Assessment of Northern Hemispheric Atmospheric Circulations to Korean Mid-Summer Surface Warming by the Atmospheric Nudging Experiment

Anomalous surface warming in Korea has been explained by the high-pressure anomaly accompanied by the vertical sinking motion and weakening of westerlies at the exit of the East Asian Jet. The large-scale circulations linked to this high pressure over East Asia are characterized by the low pressure over the Arctic (AC) and the high pressure over Western Europe (WE), East Asia, and the North Pacific (NP). To assess the contribution of these circulation anomalies to the hot summer in Korea, the four nudging experiments (AC, NP, AC + NP, and WE) are applied to the simulations with 50 different initial conditions in July. As a result, the most similar patterns on local and hemispheric scales are found in the AC + NP nudging experiment. However, the near-surface response in the AC + NP is still weak, and its center shifts to the north compared to the observed, which is induced by the weaker diabatic contribution for the downward motion in the nudging experiment. Using the quasi-geostrophic omega equation, we find that the simulated radiative feedback process is not sufficient to build up the large-scale subsidence with the short nudging period. Despite this limitation, AC + NP well simulates the coherent sinking motion and high-pressure system near Korea by the vorticity advection associated with the upper-level westerlies. It implies that the contribution of the North Pacific circulation (a downstream region) should also be considered to reasonably simulate the East Asia surface warming along with those in the upstream regions.

How did a tailings spill change the distribution of legacy organochlorine compounds in a Southeast Atlantic inner shelf area: Is a hidden danger being transferred to the ocean?

Polychlorinated biphenyls (PCBs) and dichloro-diphenyl-trichloroethane (DDT) were evaluated in water and sediments from the Espírito Santo Inner Shelf (ESIS), Brazil, three years after the Fundão dam failure (FDF). We discuss the levels, sources, fate, and current environmental risks of these contaminants on temporal and spatial scales. In addition, the associated coastal dispersion patterns, water-sediment exchange trends, and environmental alterations were also discussed. Low contributions and no environmental risks were verified for PCBs after FDF. However, the low concentrations and frequency of occurrence in the samples did not allow for further reliable conclusions regarding the source of this contaminant. In contrast, hazard risk has been detected for DDTs in water and sediments. In sediments, there were a significant increase in level (up to 13.42 ng g−1; outlier = 369.6 ng g−1), inventory (maximum = 35.98 ng cm−2) and mean total mass (21.1 ± 39.4 kg) of DDTs after FDF. The integrated assessment of the spatial distribution in water and sediment suggests that DDTs was released from the Doce River, travelled south by the water column, and returned to the mouth region by northward sediment transport, where it accumulated. However, intense rainfall increased the input of DDTs to the ESIS and may have also altered its spatial distribution. Fugacity fraction analysis (ƒƒ) indicated a net flux of DDTs from water to sediment, suggesting that vertical sinking was an important transport process in this area. Finally, the findings indicate that FDF contributed to DDTs input on ESIS by remobilizing contaminated past sediments and soils from the Doce River drainage basin. This contribution is expected to continue since a large amount of tailings is still stored in the river basin and estuary. These results highlight the importance of assessing the indirect impacts of large-scale land disasters on marine environments, and may be helpful in future interpretations of additional local trends and global inventories of legacy pollutants.

Numerical investigation of the three-dimensional paths of plastic polymers in the Gulf of Naples

The high-resolution Campania Regional Ocean Model (CROM), coupled with an online Lagrangian particle tracking algorithm, is used to investigate the horizontal and vertical behavior of different (in terms of size and density) plastic polymer types during February and August 2016 in the Gulf of Naples. The transport of passive particles is evaluated based on the three-dimensional Eulerian velocity fields provided by the ocean model. The virtual particles are released in several hot spot areas in the Gulf of Naples where most of the marine debris is supposed to come from. A sensitivity analysis on the vertical sinking for negatively buoyant particles is carried out. The sinking behavior is determined by the settling velocity, which depends on the physical properties of the individual litter item as well as on the hydrodynamical features of the marine environment. Different numerical experiments are carried out to evaluate the effect of marine dynamics on three-dimensional transport.

Vertical flux of microplastic, a case study in the Southern Ocean, South Georgia

Estimated plastic debris floating at the ocean surface varies depending on modelling approaches, with some suggesting unaccounted sinks for marine plastic debris due to mismatches between plastic predicted to enter the ocean and that accounted for at the surface. A major knowledge gap relates to the vertical sinking of oceanic plastic. We used an array of floating sediment traps combined with optical microscopy and Raman spectroscopy to measure the microplastic flux between 50 and 150 m water depth over 24 h within a natural harbour of the sub-Antarctic island of South Georgia. This region is influenced by fishing, tourism, and research activity. We found a 69 % decrease in microplastic flux from 50 m (306 pieces/m2/day) to 150 m (94pieces/m2/day). Our study confirms the occurrence of a vertical flux of microplastic in the upper water column of the Southern Ocean, which may influence zooplankton microplastic consumption and the carbon cycle.

ОЦІНКА МОЖЛИВОСТІ РЕГУЛЮВАННЯ ВОДНОГО РЕЖИМУ ОКРЕМИХ ТЕРИТОРІЙ ЧОРНОБИЛЬСЬКОЇ ЗОНИ ВІДЧУЖЕННЯ

The characteristics of the natural features of the Chernobyl Exclusion Zone (CEZ), in particular the nature of the relief, soil cover, main plant groups, and landscape characteristics, are provided. The hydrographic network of the region is detailed, represented by rivers, lakes, ponds, dams of the Pripyat and Uzh rivers, the reservoir of the Kyiv HPP, reclamation channels, water mirrors in front of filtration dams. It was noted that the main processes that form the current level of radioactive contamination of water systems in the CEZ are natural processes of radioactive decay, vertical sinking and geochemical fixation of radionuclides. Analysis of water pollution monitoring data in rivers and canals of the exclusion zone shows that by regulating water levels in most areas of the catchment areas of the CEZ, it is impossible to significantly influence the reduction of water pollution in them compared to the effects of their natural self-purification. Therefore, it is impractical to continue large-scale works on water flow regulation by hydrotechnical structures in order to minimize the removal of radioactive substances beyond the exclusion zone. It is advisable to leave in operation only those systems that allow maintaining increased moisture in peatlands, reducing the risks of fires. The studies carried out on the reclamation system “Buryakivka” in the basin of the Sakhan River, as an experimental training ground for the regulation of the regime of floodplains of the CEZ, are covered in detail. The use of the method of remote sensing of the Earth (DSS) to control the water regime and monitor the transformation of reclamation systems into wetlands is substantiated. In particular, spectral analysis of image pixels in different parts of the spectrum using vegetation indices. A positive nature protection effect from the increase in the area of wetlands in the Exclusion Zone was noted in the context of the prospects of climate change and in the context of the probability of increasing cases of dry periods in the territory of Polissia.

Dynamic synergistic effects of large-scale three-dimensional circulation anomalies on the record-breaking cold wave in February 2021 in North America

In contrast to previous studies that mainly focused on the influence of the polar vortex in the horizontal circulation on the local cold air, this study uses the three-pattern decomposition of global atmospheric circulation (3P-DGAC) to reveal the dynamic synergistic effects of horizontal circulation, local meridional circulation, and local zonal circulation on cold waves, by examining the record-breaking extreme cold wave (ECW) in February 2021 across North America. In terms of horizontal circulation, this ECW is preceded by the strengthening of blocking highs over the North Pacific and North Atlantic that force the tropospheric polar vortex edge toward North America, resulting in the development of the North American trough. The strongly northwesterly wind caused by the North American trough strengthens the local meridional circulation over North America, transporting cold Arctic air to the mid-low latitudes. Meanwhile, the local meridional circulation over North America strengthens the ascending motion and subsequently promotes the development of local zonal circulation over the North Atlantic. In turn, the developed local zonal circulation reinforces the blocking highs over the two oceans, slowing the movement of the trough and ridge systems eastward and leading to a long duration for this ECW. The composite analysis further conforms that the vertical sinking motion corresponding to blocking highs over the two oceans is mainly contributed by the local zonal circulation, and the strong local zonal circulation over the North Atlantic could lengthen the duration of the cold wave by strengthening the blocking highs. This study suggests that 3P-DGAC is an effective tool for investigating the three-dimensional structural characteristics of anomalous circulations in ECWs.

Characteristics and Meteorological Effects of Ozone Pollution in Spring Season at Coastal City, Southeast China

Surface ozone (O3) pollution has become one of the top environmental issues in recent years around the world and can be influenced by meteorological processes on multiple scales. Understanding the meteorological mechanism and contributions of O3 pollution is of great importance for O3 mitigation. In this study, we explored the impacts of meteorological conditions on O3 concentrations in a coastal city in Southeast China, with a particular focus on O3 pollution episodes inspringtime. A significant increase in the O3 pollution ratefrom 2015 to 2020 was observed (41.7% year−1) and the seasonal characteristics of O3 concentrations showed a two-peak pattern. We selected 12 pollution episodes during the springtime of 2015 to 2020 and identified four dominant synoptic weather patterns (SWPs) that could cause O3 pollution. The local meteorological conditions and vertical dynamic structures under different SWPs were analyzed. The results showed that high O3 levels tend to be associated with high temperature, weak wind, low relative humidity, and deep vertical sinking motion. We also established a quantitative linkage between the O3 values and meteorological factors. Based on meteorological conditions, 60.8~80.8% of the variation in O3 can be explained.

Reduced bacterial mortality and enhanced viral productivity during sinking in the ocean

Particle sinking is an important process in the ocean, influencing the biogeochemical cycle and driving the long-term preservation of carbon into the deep sea via the biological pump. However, as an important component of marine ecosystems, the role of viruses during sinking is still poorly understood. Therefore, we performed a series of transplantation experiments in the South China Sea to simulate environmental changes during sinking and investigate their effects on viral eco-dynamics and life strategy. Our study demonstrated increased viral production but decreased virus-mediated bacterial mortality after transplantation. A larger burst size and switch from the lysogenic to lytic strategy were shown to contribute to enhanced viral productivity. We provide experimental evidence that surface viral ecological characteristics changed dramatically after transplantation into deep-sea waters, indicating a potential importance of viruses during vertical sinking in the ocean. This effect probably provides positive feedback on the efficiency of the biological pump.

Sink versus tilt penetration into shaken dry granular matter: The role of the foundation.

We study the behavior of cylindrical objects as they sink into a dry granular bed fluidized due to lateral oscillations. Somewhat unexpectedly, we have found that, within a large range of lateral shaking powers, cylinders with flat bottoms sink vertically, while those with a "foundation" consisting of a shallow ring attached to their bottom, tilt besides sinking. The latter scenario seems to dominate independently from the nature of the foundation when strong enough lateral vibrations are applied. We are able to explain the observed behavior by quasi-2D numerical simulations, which also demonstrate the influence of the intruder's aspect ratio. The vertical sink dynamics is explained with the help of a Newtonian equation of motion for the intruder. Our findings may shed light on the behavior of buildings and other manmade structures during earthquakes.

Peculiarities of passing through a temperature gradient in vertical shaft sinking with artificial ground freezing

Peculiarities of passing through a temperature gradient in vertical shaft sinking with artificial ground freezing

Impact of mesoscale eddies on the source funnel of sediment trap measurements in the South China Sea

The mooring tethered time-series sediment traps (TS-traps) collect sinking particles in the ocean, enabling the estimation of biological pump (BP) efficiency based on the assumption of vertical settling. However, the advection of sea water can disperse particles over long distance during the sinking process, introducing uncertainties into the estimates of BP efficiency. In the South China Sea, mesoscale eddies generate significant lateral transport above the mesopelagic zone, which has a large impact on the collecting area and source funnel of TS-traps. We studied the role of eddies in the lateral transport of sinking particles using a Lagrangian Particle Tracking Model (LPTM) which was forced by three-dimensional currents of eddy composites derived from the global Hybrid Coordinate Ocean Model (HYCOM). The eddy reanalysis using the HYCOM outputs was validated using occurrence, genesis and dissipation statistics of eddies. Backward particle tracking was performed at three stations located in the northern, central and southwestern SCS, respectively. The results indicate that the vertical sinking assumption is invalid when the particle sinking velocity is relatively low. Furthermore, the fraction of surface sources from the edge of the eddies depends on both the sinking velocity and seasonal variability of the background current. The eddy current controls the movement of particles within the eddy, and many of the particles with a sinking velocity <80 m d−1 can be transported from the edge to the eddy center. The source funnel within the mesoscale eddy is tilted vertically, leading to an asymmetrical distribution of the particle source around the trap location. Finally, for slow-sinking particles, trap-collected particles could originate from the subsurface located tens to hundreds of kilometers away from the trap location. Overall, our results highlight the role of mesoscale eddies in interpreting trap measurements.

Numerical simulation of vertical shaft sinking using artificial ground freezing

Artificial ground freezing (AGF) is used worldwide for vertical shaft sinking in difficult hydrogeological conditions. The modern tendency is to determine the design parameters of the freezing technique based on numerical simulation. This work is devoted to the numerical simulation of the formation of an ice-soil wall in the soil stratum due to the AGF and shaft sinking under the protection of the wall. For this purpose, a fully coupled thermo-hydro-mechanical model of soil freezing has been developed on the basis of the theory of poromechanics. The developed model considers important features of the freezing process, such as the phase change, pore water migration due to cryogenic suction, frost heave, and consolidation of the soil. The results have shown that the model allows to predict the distribution of ice content, assess stress and strain in the ice-soil wall, and estimate displacement of the excavation wall.

Modelling and Simulation of Vertical Fin Style Aluminium Heat Sink for Controlled Thermal Compensation in Absorber Loaded Antenna Array

Enhanced array performance can be achieved by increasing number of array elements but at the cost of increased side lobe levels. These sidelobes can be supressed by integrating graphene oxide based electromagnetic absorbers along with antenna array on a single substrate. Absorbers can effectively reduce the side lobe levels of array by absorbing their interelement coupling waves, the ambient temperature of array however increases as the absorbed side lobes dissipate into heat which is not desirable. Temperature compensation technique is hence proposed whereby the temperature shift is controlled by utilizing heat sink mounted absorber for improving the performance of antenna array.

Source-to-sink system for peat accumulation in marginal basins of the South China Sea with the Qiongdongnan Basin as an example

In the coal-bearing deposits of the Qiongdongnan Basin in the South China Sea, coal seams are for the most part extremely thin, typically less than 0.5 m. Coal streaks are commonly observed but are not concentrated. In addition, the ash content of the coal components is very high, indicating that the geological conditions of peat accumulation and coal formation were very unstable. For these reasons, it can be speculated that at the time of development, peat mires were relatively poor, in terms of inheritance and continuity, and were commonly not preserved. Coal measures, coal seams (in situ peat accumulation over long distances) and dispersed terrigenous sedimentary organic matter, which together constitute a type of complex coal source-to-sink system found in basin-marginal basins, include three aspects. (1) The material is homologous: whether autochthonous accumulation, allochthonous accumulation or dispersed organic matter is present, the total organic matter source is homologous, i.e. suitable for development and plant growth. (2) The process of organic matter transport (channel) is divided into three forms: vertical accumulation in situ, transport to relatively fixed areas by flowing water, and transport by other mechanisms with long-distance dispersion and drift. (3) There are three types of aggregation forms: vertical accumulation in situ, transport from flowing water to relatively fixed areas away from where plants grow and aggregate, and deposition in deep-water basins fixed with other substances; the latter type requires a period of time for long-distance dispersion and drift, including channel flow and surface flow. KEY POINTS From plant growth to peat formation, the ‘source–channel–sink system’ of coal formation is ‘sensitivity to sedimentary environments and complexity of distribution’. Convergence of coal-series, coal seam (in situ peat aggregation and allochthonous aggregation), and terrestrial dispersed organic matter deposition, constitute a complex coal-measure source–sink system. Source includes substance homology, channels include in situ vertical accumulation and dispersion drift in short and long distances, with convergence forms including in situ vertical accretion, remote sink and dispersion in deep-water basin.

ОБ ОПЫТЕ И ПЕРСПЕКТИВАХ ПРИМЕНЕНИЯ ТЕХНОЛОГИЙ ПРОХОЖДЕНИЯ ВЕРТИКАЛЬНЫХ СТВОЛОВ В УКРАИНЕ

Purpose. Analysis of production experience, scientific and technical developments and assessment of the prospects for the application and development of technologies for the construction of vertical shafts in Ukraine in the context of the need to restore the coal mining industry to preserve the energy independence of the state. Methodology. The methods of analysis of the accumulated production experience of shaft sinking in Ukraine, in the post-Soviet space and in the leading mining countries, as well as scientific and technical literature were used. Results. The classification of technologies and methods of vertical shaft sinking is considered and supplemented, technological schemes and equipment used and promising for Ukraine for the construction of shafts by conventional and special methods are analyzed, the production experience of the Donetskshakhtoprokhodka and Spetsshakhtobureniie trusts is generalized from the point of view of applicability in the construction of shafts of block No. 12 of PJSC Shakhtopravlenie Pokrovskoe”. The possibility of using a modified parallel technological scheme of shaft sinking has been substantiated. The prospects of mechanized shaft sinking in Ukraine – by drilling and with the use of shaft-sinking machines – are assessed. The characteristics of the conditions for the construction and operation of shaft lining, the final element of the shaft, as a structure and functional complex are given. Variants of combined lining, including those with the use of fiber-reinforced concrete, are considered. Scientific novelty. The results of the analysis of technological schemes and methods of vertical shafts sinking, accumulated production experience and scientific and technical developments are generalized, trends and prospects for the development of technologies are considered. Practical value. The analysis of technological schemes and methods of sinking vertical shafts was carried out on the basis of domestic and foreign production experience. Key words: vertical shaft, sinking technology, shaft sinking flow chart, drilling and blasting operations, shafts drilling, shaft-sinking machine.

How Quickly Can a Submarine Dive?

A two-equation model is developed to describe the descent of a submarine as it floods its ballast tanks. The flow into the tanks is assumed to be inviscid, and the drag on the vertical sinking motion of the craft is neglected. The two coupled differential equations are the generalized form of Newton’s second law and the Bernoulli relation. Time derivatives are converted to spatial derivatives to decouple the equations, and the resulting second-order equation is solved using the Euler–Cromer algorithm. The theory and the method of numerical integration are suitable for an intermediate-level undergraduate course in mechanics that includes some basic fluid dynamics.

Numerical analysis of application limits of Vyalov’s formula for an ice-soil thickness

Artificial ground freezing is an efficient technique which allows one to sink the mine shafts under complex hydrogeological conditions. The aim of artificial ground freezing is a creation of a temporary wall of frozen soil around the intended excavation. To estimate an optimal thickness of an ice-soil wall, the Vyalov’s formula is widely used by engineers. The article is devoted to analysis of Vyalov’s formula on the basis of the numerical simulation. The numerical simulation has been conducted by the finite element method. For the simulation of a stress-strain state of an ice-soil wall a new computational scheme has been proposed. The scheme is based on Vyalov’s design layout for a vertical shaft sinking and takes into account a soil layer beyond the excavation bottom. A mechanical behavior of frozen soil is described by Vyalov’s constitutive relations. As a result, it has been shown that values of the wall thickness given by Vyalov’s formula do not agree with the ones obtained by the numerical simulation. In order to conform results given by Vyalov’s formula and the numerical simulation, two modifications of the formula have been proposed.

Tibetan Plateau heating as a driver of monsoon rainfall variability in Pakistan

Pakistan summer monsoon rainfall consists of a large portion of the local annual total rainfall, and in the recent monsoon seasons, prolonged periods of anomalous rainfall and excessive flooding have appeared in Pakistan. A full understanding of the monsoon rainfall variability is important for the sustainable development of the country. Based on multiple data analyses and the weather research and forecasting model, the potential impact of Tibetan Plateau (TP) heating on the interannual variability of Pakistan monsoon rainfall is investigated. It is observed that a significant negative relationship exists between the thermal forcing over the southeastern TP and Pakistan monsoon rainfall in July–August. Both the data analyses and model sensitivity experiments identify that the TP heating drives a Rossby wave response in the upper atmosphere characterized with an anticyclonic anomaly over the southern TP but a cyclonic anomaly to the north. This dipole pattern of anomalous circulation induces an evident upper-level convergence over Pakistan, corresponding with remarkable vertical sinking motion. Meanwhile, in the lower troposphere, the TP heating causes anomalous westerly wind along the Himalayas over the northern India continent. Such westerly anomaly further induces less water vapor transport into Pakistan from the Bay of Bengal. Therefore, both the dynamic and thermodynamic processes regulated by positive TP heating are not beneficial for the occurrence of monsoon rainfall in Pakistan. This study proposes a new potential mechanism in which TP heating acts as a driver of Pakistan monsoon rainfall variability on interannual time scales.