Dominant Direction Research Articles

The effects of wind-wave disturbances on sediment resuspension and phosphate release in Lake Chao

As a typical shallow lake with a wind-generated flow, the resuspension state of sediment and phosphorus release under wind field disturbance plays an important role in controlling lake eutrophication in Lake Chao. In this study, we proposed a combination of experimental analysis of dynamic disturbances, wind-wave disturbance shear stress calculation, and model simulation (experimental-calculative-modeling) to quantitatively investigate the effects of wind-wave disturbances on the resuspension state of Lake Chao bottom sediment and phosphorus release and distribution. The results showed that the release rate of phosphorus from the Lake Chao bottom sediment was affected by the wind field and bottom sediment content, which varied significantly spatially and showed some difference between different seasons. Under the condition of sufficient water body disturbance, the substrate in the Western Lake area of Lake Chao mainly adsorbed phosphate from the water body, while the substrate in the Central Lake area and the Eastern Lake area adsorbed phosphate along with the release. The magnitude of the phosphorus release rate due to sediment resuspension was mainly affected by wind speed, and the distribution of phosphorus content was influenced by the circulation generated by different dominant wind directions. The wind-wave disturbances have a significant effect on the spatial and temporal distribution of phosphorus in Lake Chao, and the proposed experimental-calculative-modeling ensemble can provide relevant technical support for the study of water pollution control strategies and comprehensive remediation and management of Lake Chao.

Variation of Local Wind Fields under the Background of Climate Change and Its Impact on Algal Blooms in Lake Taihu, China

Global climate change can greatly promote the continuing expansion of algal blooms in eutrophic inland lakes. Wind fields, an important climate factor, provide an external driving force for the movement of algal blooms. Based on algal bloom satellite imageries and wind observation data from 2003 to 2022, this study explored a quantitative assessment of the variations in surface wind fields and their impacts on the algal blooms in Lake Taihu, China. The results indicate that the mean wind speed at different time scales in the Lake Taihu area presents a continuous descending tendency in recent decades, which is the probable cause for the increasing frequency and severity of algal blooms in the lake. Wind fields affect the formation, location, and severity of algal blooms in diverse and complex ways. The area and frequency of algal blooms in Lake Taihu increase with the decrease in wind speed. The 6 h mean wind speed before 12:00 LT (Local Time) on the day of the algal bloom occurrence generally follows a Gaussian distribution, with a wind speed range of (0.6 m/s, 3.4 m/s) at the 95.5% confidence level. Accordingly, the wind speeds of 0.6 m/s and 3.4 m/s are identified to be the lower and upper critical wind speed indicators suitable for the formation of algal blooms, respectively. Another meaningful finding is that the outbreak of large-scale algal blooms requires stricter wind speed conditions, with a significantly lower wind speed threshold of around 2 m/s. Our study also demonstrates that the dominant wind direction of southeast in the region may be an important cause of the continuous water-quality decline and the high frequency and severity of algal blooms in the northwest waters of the lake. These findings will contribute to further studies on the dynamic mechanism of algal blooms and provide support for water environment management and algal bloom prevention and control.

Impacts of maritime shipping on air pollution along the US East Coast

Abstract. Air pollution is considered a leading threat to human health in the US and worldwide. An important source of air pollution in coastal areas is the globally increasing maritime shipping traffic. In this study, we take a high-resolution modeling approach to investigate the impacts of ship emissions on concentrations of various atmospheric pollutants, under the meteorological conditions and emissions of the year 2018. We utilize the Comprehensive Air Quality Model with extensions (CAMx) to simulate transport, diffusion, and chemical reactions and the Weather Research and Forecasting (WRF) model to provide the meteorological inputs. We focus on four criteria pollutants – fine particulate matter with a diameter smaller than 2.5 µm (PM2.5), nitrogen dioxide (NO2), sulfur dioxide (SO2), and ozone (O3) – as well as nitrogen oxide (NO), and we calculate their concentrations in the presence and absence of ship emissions along the US East Coast, particularly in the proximity of major ports. We find that ship emissions increase the PM2.5 concentrations over the ocean and over a few areas inland. The 98th percentile of the 24 h average PM2.5 concentrations (the “design value” used by the US Environmental Protection Agency) increased by up to 3.2 µg m−3 in some coastal areas. In addition, ships contribute significantly to SO2 concentrations, up to 95 % over the Atlantic and up to 90 % over land in coastal states, which represents a ∼45 ppb increase in the SO2 design values in some states. The 98th percentile of the hourly NO2 concentrations also increased by up to 15 ppb at the major ports and along the shore. In addition, we find that the impact of shipping emissions on O3 concentrations is not uniform, meaning that ships affect ozone pollution in both positive and negative ways: over the ocean, O3 concentrations were significantly higher in the presence of ships, whereas O3 concentrations decreased in the presence of ships in major coastal cities. Our simulation results show that ships emit significant amounts of fresh NO in the atmosphere, which then helps scavenge O3 in volatile organic compound (VOC)-limited areas, such as major ports. By contrast, over the ocean (NOx-limited regime), enhanced NOx concentrations due to ships contribute to the formation of O3 and therefore enhance O3 concentrations. Overall, due to the dominant southwesterly wind direction in the region, the impacts of ships on air pollutants mainly remain offshore. However, in coastal states near major ports, the impacts are significantly important.

Fracturing parameter optimization technology for highly deviated wells in complex lithologic reservoirs

Highly-deviated wells are the key technology to reduce the risk of drilling accidents and improve the utilization of reservoirs. However, for reservoirs with complex lithology, highly-deviated wells are faced with the problems of geomechanical transformation and fracturing parameter optimization. The research on fracturing parameter optimization technology of high-deviated wells in complex lithologic reservoirs is helpful to the research and application of geomechanics in deep unconventional reservoirs. This paper is based on geological mechanics laboratory experiments and logging interpretation, combined with regional geological background, to clarify the geological and mechanical characteristics of the Fengcheng Formation shale oil region in the Mabei Slope. On this basis, based on the current geostress field and natural fracture distribution pattern of the Mabei Slope, an integrated model of shale oil geological engineering in local well areas was established. Based on the finite element method, optimization design was carried out for the cluster spacing, construction fluid volume, displacement, and sand volume of highly deviated well fracturing, and three-dimensional simulation of fracturing fractures was completed. The research results indicate that: (1) The current dominant direction of the maximum principal stress in the Fengcheng Formation on the Mabei Slope is from northeast to southwest, with the maximum horizontal principal stress generally ranging from 90 to 120 MPa and the minimum horizontal principal stress generally ranging from 70 to 110 MPa. (2) The difference in stress between the two horizontal directions is relatively large, generally greater than 8 MPa. Two sets of natural fractures have developed in the research area, one with a northwest southeast trend and the other with a northeast southwest trend. The natural fracture density of the Fengcheng Formation shale reservoir in the Mabei Slope is 0.32–1.12/m, with an average of 0.58/m, indicating a moderate to high degree of fracture development. (3) The geological model and three-dimensional geo-mechanical model are established according to the actual drilling geological data, and different schemes are designed to carry out single parameter optimization. The optimization results show that the optimal cluster spacing of the subdividing cutting volume pressure of the highly deviated wells in the Fengcheng Formation of the Mabei Slope is 12 m, the optimal construction fluid volume is 1400–1600 m3/section, the optimal construction displacement is 8 m3/min, and the optimal sanding strength is 2.5 m3/m. At the same time, by comparing the fracturing implementation effect with the fracturing scheme design, it is proven that the artificial parameter optimization method for highly deviated wells based on the finite element method based on the regional stress background and the natural fracture development law proposed in this paper is feasible and can provide a scientific basis for the fracturing development of highly deviated wells in complex lithologic reservoirs. This research has been well applied in Mahu area of Xinjiang oilfield.

Topoğrafya ve Meşcere Yapısının Rüzgâr Devriği Zararlarına Etkisinin Araştırılması: Düzce Orman İşletme Müdürlüğü Örneği

Aim of study: The aim of the study was to determined the tree volume and damage level in windthrow areas and to assess the impact of topographic factors and forest structure on windthrow damaged.
 Area of study: Our study was conducted within the Düzce Forest Management Directorate.
 Material and methods: The windthrow areas within the boundaries of Düzce Forest Management Directorate were obtained from extraordinary yield reports. According to windthrow data verified using Google Earth, the borders for each damage were determined and transferred to ArcMap. The relationships between windthrow areas and enviromental parameters were determined using digital maps and forest management plans. Correlation analysis was applied to find out the relationship between windthrow areas and topographic and forest characteristics. Additionally, variance analysis was performed to determine if there were differences in terms of dominant aspects and forest types between windthrow areas and amounts. T-tests were conducted to determine if there were differences between windthrow areas and amounts and the dominant wind direction. Based on the statistically significant results, an intersect analysis was applied to environmental parameters to generate a windthrow susceptibility map.
 Main results: Windthrow occurred mostly in the southwest aspect, in the Fir-Beech species and in the cd age classes. A statistically significant relationship (p

Поговорим о пермеатах

The article focuses on the ambiguous interpretation of the term «permeate». The dominant directions of membrane fractionation with the production of various permeates are analyzed.

ON ACCELERATION OF THERMAL SIMULATION OF URBAN SCENES WITH THE APPLICATION OF AN EVOLUTIONARY ALGORITHM TO TREE PLANTING STRATEGIES

Abstract. Tree planting is one of the most popular in urban morphology measures for urban heat island reduction since, at a relatively low monetary cost and with a marginal alteration of the scene, trees provide shadows and neutralize harmful gases. Findings for their optimal distribution within the urban scene exist in numerous environmental studies. However, merely the digital twin of the scene possesses the capability to analyze further developments of the scene, such as changes in dominant wind directions. Today’s extensive computational resources allow for thermal simulations of digital twins on multiple (not-yet-existing) urban scene designs, aiming at minimizing the average or peak temperatures. From the point of view of computer graphics, this paper proposes four tools to accelerate an evolutionary algorithm for tree planting strategies. Using GPU arrays for rendering, pre-rendering default scenes, and pre-filtering trees in the early morning and late evening hours helps accelerating the rendering process. Computation of fitness function on different computers allows a further acceleration of the evolutionary algorithm. The total acceleration factor of a scene using computational set-up exceeds 218, thus demonstrating the enormous potential the evolutionary algorithm may bring about in future investigations.

РЕЗУЛЬТАТЫ ГЛУБИННЫХ МАГНИТОТЕЛЛУРИЧЕСКИХ ИССЛЕДОВАНИЙ В РАЙОНЕ СЛОБОДСКОГО ГЕОДИНАМИЧЕСКОГО УЗЛА (ВОСТОЧНО-ЕВРОПЕЙСКАЯ ПЛАТФОРМА)

The Sloboda Geodynamic Intersection is considered as an area of convergence for major segments, aulacogens, faults, and suture zones of the East European Platform.Between 2020 and 2022, researchers from the Geological Faculty of Lomonosov Moscow State University and the Geoelectromagnetic Research Center (GEMRC IPE RAS) conducted deep magnetotelluric surveys in this region. The surveys were performed along the Pushkiny Gory – Andreapol, Sebezh – Velikiye Luki – Rzhev, and Ostrov – Ostashkov profiles. Through qualitative analysis of the collected data, the dimensionality of the studied medium, the total longitudinal conductance of the sedimentary cover, and the dominant strike direction of conductive structures were assessed. Quantitative interpretation using 1D, 2D, and 3D inversions resulted in geoelectric models comprising a conductive sedimentary cover and a highly resistive basement. Within the depth range of 10–40 km, transcrustal zones of enhanced electrical conductivity were consistently identified, interpreted as the southwest extension of the Ilmen-Ladoga anomaly. These conductivity anomalies are attributed to the deep submergence of heavily tectonized and metamorphosed sedimentary rocks, initially saturated with organic and carbonate matter.

Characteristics of wind-sand transportation along railways in the eastern fringe of the Taklimakan Desert and sand control system

Abstract This paper focuses on the Korla-Ruoqiang desert railway line, utilizing ERA5 (ERA5 is the fifth generation of ECMWF (European Centre for Medium-Range Weather Forecasts) atmospheric reanalysis global climate data) wind data to conduct a comprehensive analysis of the wind energy environment along the line in all aspects, reveals the characteristics of wind-sand transport, and puts forward the countermeasures to prevent and control wind-sand disasters. The results of the study indicate that: (1) the wind-sand along the line mainly occurs in the spring and summer seasons, and the dominant sand-moving directions are easterly (ENE, E and NNE) and northeasterly (NE). (2) The average annual sand-moving wind speed ranges from 5.80 m/s to 7.25 m/s, and the annual frequency of sand-moving ranges from 11.99% to 37.26%. (3) The annual sand drift potential (DP) along the line ranges from 69.20 VU to 607.24 VU, with three types of wind energy environments: low, medium and high. The resultant drift potential (RDP) ranges from 45.52 VU to 547.49 VU, and the wind variability index (RDP/DP) is between 0.54 and 0.90. (4) The average sand transport quantity along the line ranges from 2.92 m³/m/a to 9.09 m³/m/a. Based on these results, we optimize the sand blocking, sand fixing and wind erosion prevention measures for different types of wind-sand environments, establish a scientific and efficient wind-sand protection and control system to solve the wind-sand problems and provide a scientific foundation for the prevention and control of wind-sand disasters along the line.

Characteristics of droplets emission immediately around mouth during dental treatments

Control measures aiming for removing droplets generated during dental treatments have been attracted increasing attention after COVID-19 pandemic, but the emission characteristics of droplets around the source (namely, the mouth) have still not been fully understood. The present study investigated experimentally the emission characteristics of droplets around mouth during typical dental treatments. A manikin being treated by portable dental instruments simulated the dental treatments, while the laser light scattering technique and particle image velocimetry (PIV) technique were employed to perform the measurements. The peak mass fraction of droplets occurs around the droplet size from 20 μm to 100 μm, while the mass fraction of droplets with the diameter less than 200 μm accounts for over 80 %. By fitting with the Rosin-Rammler equation, the mean size of droplets (d‾) are 54.96 and 98.93, and the size distribution parameter (n) are 1.35 and 1.58, respectively, for the process of air-powder-polishing and ultrasonic scaling. The dominant emission direction of droplets is towards the dummy’ head and chest. The emitted droplets formed approximately a cone shape, and its angle varied from 25° to 83° for different conditions. The maximum velocity of droplets at the location near the dummy's mouth exceeds 1.0 m/s for most conditions. The injecting flow rate and treated tooth position are the major factors influencing the emission direction, angle, and velocity. It is expected that the results can further increase our understanding of emission characteristics of droplets and provide accurate initial conditions for CFD simulations.

Wind Energy Resources at Antarctic Stations Based on ERA5

The harsh scientific research environment of Antarctic stations demands a reliable energy supply; however, traditional methods not only pose a challenge in supply but also harm the environment. Antarctic energy supply has become a new choice for energy development in Antarctica due to its abundant wind energy resources. Using ERA5 10 m wind field reanalysis data, we compared and analyzed the correlation (r) and Root Mean Square Error (RMSE) between some observation stations and reanalysis data, with correlations above 0.67 and root mean square error below 2.3. This indicates that the accuracy of the ERA5 data is suitable for resource assessment at stations in Antarctica. We assessed the wind energy potential of the Great Wall, Zhongshan, Kunlun and Taishan Stations. The results show that the annual distribution and long-term trend of wind energy at Taishan Station are the best, followed by the Great Wall, Zhongshan and Kunlun Stations. Taishan Station has stable wind direction and abundant wind energy, the average wind power density is 800 W/m2, with an annual growth trend of 2.02 W/m2·yr−1. The effective wind speed occurrence and energy level occurrence are generally above 90% and the coefficient of variation is generally below 0.8. The dominant direction of wind energy is northeast and the wind direction is stable, which is conducive to the development and utilization of wind energy.

Multiple compression directions and basinal response in a rhomb-shaped terrestrial basin: The Cuevas de Cañart syncline (Iberian Chain, eastern Spain)

Rhomb-shaped basins have been commonly attributed to strike-slip tectonics, linked to fault bends and jogs (pull-apart basins). The case-study presented in this work (Las Cuevas de Cañart basin, Iberian Chain) is a 2 km × 5 km continental basin that shows a particular combination of geometric and sedimentary features. It shows a syncline geometry with steeply-dipping limbs, thickness of syn-tectonic sedimentary continental filling of about 1000 m, high amplitude/wavelength ratio, and different fold trends, some of them oblique to the main trend of the Iberian Chain. All these features make it an interesting case of a mixed-type basin, sharing both compressional and strike-slip features. The Cuevas de Cañart basin shows a Mesozoic, pre-compressional sequence linked to the extensional processes dominating in the marginal zones of the Maestrazgo basin, with a series up to 1500 m thick of limestones, sandstones and shales. These units overlie a detachment level (Upper Triassic Keuper facies) and show thickness variations controlled by NW-SE and NE-SW striking normal faults. During the Cenozoic compression, both fault systems were re-activated, and newly formed E-W folds (perpendicular to one of the dominant shortening directions) also appeared in the southern basin margin. The detailed structural study of this basin evidences the role of different types of structures (basement faults, thrusts formed under different compression directions) and the relevance of the detachment level in the evolution of compressional basins and thin-skinned fold-and-thrust belts.

Dominant A1 Direction as an Additional Factor for Deciding Surgical Approach for A1 Bifurcation Aneurysms

Background and ObjectivesClipping of the Anterior communicating artery (AcomA) located aneurysms is considered a critical surgical procedure for neurosurgeons worldwide due to the complexity of the surgical area. The present study is conducted to discuss the importance of the geometrical curvatures and the direction of the dominant A1 artery and their impact on aneurysmal growth direction and choice of side selection of the Pterional surgical approach side. MethodsThe present study enrolled 183 patients with ruptured AcomA-located aneurysms. the aneurysms were all treated surgically through a Pterional approach. Because of multiple dominant A1 direction, we divided the artery into 2 segments and based on the second segment direction we categorized the patients into Ascending A1, Descending A1, and Horizontal A1 groups. The ascending group includes the superiorly projecting aneurysms, while the horizontal and descending groups include the anteriorly and inferiorly projecting aneurysms respectively. Contralateral Pterional approach to the dominant A1 was chosen for aneurysms with an ascending artery. However, the ipsilateral Pterional approach was conducted in horizontal and descending A1 dominant groups. ResultsThe aneurysmal growth projection axis always follows the direction of the second dominant A1 segment. Full neck control with satisfactory perforators inspection was achieved through the contralateral approach in most cases of an ascending A1 especially if ipsilateral A2 is posterior to the neck. The A1 segment can be satisfactorily seen from the contralateral exposure before the Aneurysmal neck is exposed in ascending A1 geometries. ConclusionA1 direction is an important additional factor that is to be considered for side selection when deciding Pterional exposure of A1 bifurcation aneurysms. Accessing the contralateral dominant ascending A1 has better visualization of the neck than entering from ipsilateral approach especially if the ipsilateral A2 was posterior to the neck.

FACTORS AND DIRECTIONS OF CHANGES ON THE GRAIN MARKET IN POLAND DURING THE WAR IN UKRAINE

The study addresses the problem of identifying the impact of the conflict in Ukraine on the situation on the grain market in Poland. The analysis covered price changes, the volume and structure of exports and imports. The effects of the crisis in the field of trade policy were assessed. The source of materials for the analyzes was the literature on the subject and empirical research conducted by various institutions dealing in trade in agricultural products. The information used in the work came from the European Agricultural Products Exchange (MATIF), the World Bank, market reports of the Ministry of Agriculture and Rural Development and the European Commission. The most up-to-date reports from the United Nations, Reuters and European institutions were also used. It was found that the situation on the cereal market is extremely dynamic. Russia’s aggression against Ukraine has caused many problems on EU agricultural markets, including grain markets. There was a significant increase in the prices of wheat and corn. There were no significant changes in foreign trade directions. In the structure of Polish grain exports and imports, corn and wheat are still the most important, and in 2022, the dominant place for wheat and corn purchases was Ukraine. However, the dominant direction of grain exports was Germany.

Biaxial stretch can overcome discrepancy between global and local orientations of wavy collagen fibres

Most frequently used structure-based constitutive models of arterial wall apply assumptions on two symmetric helical (and dispersed) fibre families which, however, are not well supported with histological findings where two collagen fibre families are seldom found. Moreover, bimodal distributions of fibre directions may originate also from their waviness combined with ignoring differences between local and global fibre orientations. In contrast, if the model parameters are identified without histological information on collagen fibre directions, the resulting mean angles of both fibre families are close to ±45°, which contradicts nearly all histologic findings. The presented study exploited automated polarized light microscopy for detection of collagen fibre directions in porcine aorta under different biaxial extensions and approximated the resulting histograms with unimodal and bimodal von Mises distributions. Their comparison showed dominantly circumferential orientation of collagen fibres. Their concentration parameter for unimodal distributions increased with circumferential load, no matter if acting uniaxially or equibiaxially. For bimodal distributions, the angle between both dominant fibre directions (chosen as measure of fibre alignment) decreased similarly for both uniaxial and equibiaxial loads. These results indicate the existence of a single family of wavy circumferential collagen fibres in all layers of the aortic wall. Bimodal distributions of fibre directions presented sometimes in literature may come rather from waviness of circumferentially arranged fibres than from two symmetric families of helical fibres. To obtain a final evidence, the fibre orientation should be analysed together with their waviness.

Boundary effect and heat vortices of hydrodynamic heat conduction in graphene

A SIMPLE like algorithm is proposed for numerically solving the Guyer-Krumhansl equations. Results show that thermal conductivity of suspended graphene depends on the heat flux boundary conditions. If the strength of the point source is fixed, only when the strength of the point sink exceeds a critical value can the heat vortices occur in the heat flux vector field. We also find that heat vortices only appear when the side length perpendicular to the dominant heat flow direction exceeds a critical value. Furthermore, the no-slip boundary condition is beneficial for the generation of heat vortices, while the specular phonon-boundary interactions can disrupt the heat vortices. These findings will contribute to experiments on heat vortex in the heat flux field of suspended graphene. Finally, it is found that the heat can flow from some cold regions to hot regions for the hydrodynamic heat conduction in suspended single-layer graphene.

Temperature variation in the South Orkney Islands, maritime Antarctic

AbstractMeteorological records at Signy Station in the South Orkney Islands (SOIs) have recently been digitized to cover the period of 1947–1995. This study compares the newly available near‐surface air temperatures at Signy with those from a nearby station, Orcadas and with reanalysis datasets to provide a more comprehensive picture of the weather and climate variability in the SOIs. Temperatures from both stations show a higher degree of variability in winter than summer, but the variability differs in terms of its relationship to the dominant wind directions and sea ice influences. The two stations differ markedly in terms of their respective warm temperature events, largely due to orography‐induced föhn winds at Signy Station as northwesterlies flow over Coronation Island. ERA5 reproduces the monthly to annual averages exceedingly well but underestimates both cold and warm tails of station temperatures. Temperature trends in the SOIs are also considered in terms of changes in large‐scale circulation and the sea surface temperature over the Brazil‐Falkland Confluence. However, caution is required in interpreting the long‐term temperature trends estimated from reanalysis data as most of the reanalyses show a cold bias before 1979, which is most likely caused by misrepresentation of the sea ice.

Long-term characterisation of directional wave spectra in the Black Sea and the Sea of Azov

Directional wave spectra describe complex sea-states in frequency and directional domains and provide more detailed information than the bulk wave parameters. Using hourly directional wave spectra hindcasted for 42 years (1979–2020), this study aims to assess long-term spectral wave climate in the Black and Azov Seas. Variance densities are averaged over the frequencies and directions for annual, seasonal, and monthly scales to determine spectral wave climate. Furthermore, The individual wave systems observed in each directional wave spectra are determined by referring to the independent spectral peak at each observation. The different sea state conditions, including the uni-modal and multi-modal wave systems, are classified and analysed; The energy, frequency, and direction of the three first prominent individual wave system peaks are deeply evaluated as a function of the sea state conditions. Occurrences as the function of spectral peak density and directions of the prominent individual wave system peaks are also computed and discussed. The results reveal that multi-modal spectra are more frequent, although the highest peak density values and lowest peak frequencies were observed within the wave spectra of uni-modal sea states. The spectral peak densities, frequencies, and directions depend on the number of wave systems in the wave spectrum and geographic location. The first peaks in the wave spectra are primarily derived from two dominant directions, and ∼54 % of the peaks had a density greater than 2 m2/Hz. In contrast, second and third peaks in the wave spectra are typically derived from three or more dominant directions and rarely exceed 2 m2/Hz density.

Biomonitoring of dairy farm emitted ammonia in surface waters using phytoplankton and periphyton

The increasing environmental abundance of reactive N (‘Nr’) entails many adverse effects for society such as soil degradation and eutrophication. In addressing the global surplus of N, there is a pressing need to quantify local sources and dynamics of Nr. Although quantified as an important anthropogenic source of Nr, the spatiotemporal patterns of ammonia (‘NH3’) emitted by dairy farming and its resulting pressure on local surface waters lacks quantification. Quantification could optimize farm management with minimized losses of valuable nitrogen and protection of freshwater ecology. This study aimed to unravel spatiotemporal dynamics of ammonia nitrogen emitted by a dairy farm in the atmospheric and aquatic geo-ecosphere. Atmospheric NH3 and aqueous ammonium (‘NH4+’) were determined over time, together with meteorological variables. Aquatic biomonitors (periphyton and phytoplankton) were employed to monitor the spatial impacts of cattle-stable emitted NH3. Atmospheric NH3 on the farm was significantly regulated by wind, sharply declining over increasing distances from the stable (average decrease in the dominant wind direction from 55.5 μg/m3 at 20 m to 5.8 μg/m3 at 500 m, in the other wind directions values decreased from 38.3 μg/m3 to 6.0 μg/m3). This was also reflected in local surface water concentrations of NH4+, with average concentrations decreasing from 37.0 mg [NH4+-N]/L at 65 m to 4.8 mg [NH4+-N]/L in the dominant wind direction, and from 1.2 to 0.7 in other directions. Periphyton biomass, total N (“TN”) and δ15N all significantly reflected spatiotemporal dynamics of atmospheric NH3 and aqueous NH4+, as did phytoplankton TN. The cattle stable significantly influenced local water quality through atmospheric spreading of NH3, and both aquatic biomonitors were influenced by and reflected dairy farm emitted NH3 with a sharp dilution over distance. This study strongly underlines the importance of atmospheric transport of dairy farm emitted NH3 and its effects on local water quality.

Analysis of hybrid exploitation of wind and wave power in the Mediterranean and the Black Sea

The hybrid use of renewables enables resource complementation by other sources when one of them is inactive. This study focuses on wind and wave hybrids in the Mediterranean and the Black Sea with the aim of quantifying the potentials, directionality, correlation, and complementarity of the two sources. The investigation includes the spatial distributions and point-wise analysis capacity factors, the relationship between wave height and period, prevailing directions of wind and wave, bivariate probability analysis of wind and wave power, correlation of wind and wave power based on Pearson and Kendall’s Tau methods, and complementarity analysis by computing the active hours of one source when the other is inactive. The energy density, correlation, and complementarity analysis are realized considering the working conditions of a wind turbine with eight different wave energy converters by taking into account their power matrices. ERA5 dataset is used as a source for the wind and wave data in the basin with over six-decade long time series for each grid point. The results indicate that the wind turbine possesses higher capacity factors. For the wind turbine, the spatial maximum is 0.5, whereas for the wave energy converters, this value is 0.16 for the Pelamis device with the highest performance among the considered devices. The relationship between the wave climate parameters is investigated by fitting the wave height and period time series to an exponential function in all study area. Results are provided as spatial distributions of function coefficient which is hoped to be useful for the researchers when only one of the variables is known. Bivariate probabilities are computed for wind and wave power, and it is seen that for the selected analysis points, the wave power has a potential between 1 and 1.5 kW/m in the most probable axial locations. Directional analysis of wind and waves resulted in a map of the prevailing directions in the study area showing that the Northwest is the dominant direction. Correlation analysis between the wind and wave power time series of devices indicates that a positive correlation is evident in the study area up to + 0.69. The main result from the complementarity investigation accompanied by the correlation analysis showed that wind complementing wave condition is much more dominant in the region.