Horizontal Dispersion Research Articles

Horizontal and vertical dispersion in a wind-driven oceanic gyre model

This study addresses the horizontal and vertical dispersion of passive tracers in idealized wind-driven subtropical gyres. Synthetic particles within a closed basin are numerically advected to analyze their dispersion under different theoretical velocity fields. Horizontal dispersion simulations incorporate the classic wind-driven Stommel circulation along with (i) surface Ekman drift associated with the Stommel wind field and (ii) inertial effects due to particle size and buoyancy. Results reveal that the Ekman drift inhibits particle dispersion across the entire domain leading to tracer concentration in a quasi-stable distribution skewed toward the western side of the basin. Similar behavior is observed with inertial particles. The equilibrium state is quantified for different diffusivity values, particle sizes, and buoyancies. For vertical dispersion, simulations incorporate the three-dimensional Ekman velocity, which includes a negative vertical component, while ignoring inertial effects. Initially, surface particles accumulate around the gyre center while slowly sinking, but they disperse across the basin once they surpass the Ekman layer and are free from surface effects. Tracers sink more on the western side of the basin, regardless of horizontal diffusivity. On average, ignoring inertial effects, particles sink less with higher diffusivity and more with lower diffusivity, suggesting a potential for high horizontal distribution of sunken tracers in the ocean.

A detailed simulation study on radionuclide dispersion under spent fuel road transportation conditions: Effects of vessel type and coniferous vegetation growth

Vegetation barriers are an important environmental characteristic of spent fuel road transportation accidents. Spent fuel vessels may be affected by force majeure factors during transportation, which leads to damage to spent fuel assemblies and containers and can cause radionuclides to gradually release from assemblies to vessels to the external environment. In this work, considering the growth periods of coniferous vegetation barriers and vessel type, a radionuclide dispersion model based on computational fluid dynamics (CFD) was established by adding a decay term and a pressure loss term. The simulations showed that, first, compared to the small (Type-II) vessel, the effects of fluid flow around the large vessel (Type-I) have a more significant impact on radionuclide dispersion. The backflow around the Type-I vessel causes leaked radionuclides to disperse towards the vessel, and the larger the vessel is, the more significant the rise of the leaked radionuclide plume tail will be due to the increased negative pressure gradient area. Moreover, the area contaminated exceeding the maximum allowable concentration by radioactivity for the Type-I vessel is reduced gradually with the growth of coniferous vegetation barriers due to the weakening of the backflow effect by growing vegetation. Second, compared to vegetation barriers of 15 years and 23 years, the horizontal distance exceeding the maximum allowable concentration of the leaked 131I dispersion from Type II vessels near vegetation barriers for 12 years is the longest. The older the vegetation barrier is, the shorter the horizontal dispersion range, and the shape of radionuclide dispersion gradually transforms from flat to semicircular with vegetation barrier growth, but this could cause a greater radioactive accumulation effect near the leakage point, and the maximum concentration of leaked 131I reached 0.54 kBq·m−3 for leaked radionuclides from the Type II vessel under vegetation barriers of 23 years. In addition, improvement suggestions based on the proposed method are presented, which will enable the Standards Institutes to apply the research methodologies described herein across various scenarios. Environmental ImplicationCompared to nonradioative pollutants, radioactive pollutants are intercepted by vegetation barriers and then migrate to the soil through leaves, stems, and roots, which can contaminate the surrounding environment. Considering the effects of vessel type and coniferous vegetation growth, a radionuclide dispersion model based on CFD was established. Suggestions for decontaminating radioactive pollution areas have been proposed based on the simulation results of hypothetical scenarios. The scenario applicability improvements based on the proposed model could assist relevant Standards Institutes to making improving measures.

Horizontal Pay Dispersion and Organizational Performance: A Meta-Analysis

Horizontal Pay Dispersion and Organizational Performance: A Meta-Analysis

Plasma Coupled Electrolyte Additive Strategy for Construction of High-Performance Solid Electrolyte Interphase on Li Metal Anodes.

High-performance lithium metal anodes are crucial for the development of advanced Li metal batteries. Herein, this work reports a novel plasma coupled electrolyte additive strategy to prepare high-quality composite solid electrolyte interphase (SEI) on Li metal to achieve enhanced performance and stability. With the guidance of calculations, this work selects diethyl dibromomalonate (DB) as an additive to optimize the solvation structure of electrolytes to modify the SEI. Meanwhile, this work groundbreakingly develops DB plasma technology coupled with DB electrolyte additive to construct a combinatorial SEI: inner plasma-induced SEI layer composed of LiBr and Li2CO3 plus additive-reduced SEI containing LiBr/Li2CO3/organic lithium compounds as an outer compatible layer. The optimized hybrid SEI has strong affinity toward Li+ and good mechanical properties, thereby inducing horizontal dispersion and uniform deposition of Li+ and keep structure stable. Accordingly, the symmetrical cells exhibit enhanced cycling stability for 1200h at an overpotential of 23.8mV with average coulombic efficiency (99.51%). Additionally, the full cells with LiNi0.8Co0.1Mn0.1O2 cathode deliver a capacity retention of 81.7% after 300 cycles at 0.5 C, and the pouch cell achieves a volumetric specific energy of ≈664Wh L‒1. This work provides new enlightenment on plasma technology for fabrication of advanced metal anodes for energy storage.

When inequality means equity: horizontal wage dispersion and the propensity to leave current employment across different organizational settings

Abstract Extant research holds that horizontal wage dispersion (i.e., wage dispersion within a hierarchical level in a firm) induces employees to leave their employment. Based on social comparison theory, we nuance this by theoretically and empirically uncovering contingencies under which horizontal wage dispersion is associated with employees staying in their current employment. Specifically, we focus on firm size and decentralization as relevant organizational contingencies. In large as opposed to small firms, employees’ productivity may vary significantly within hierarchical levels, causing employees to consider high horizontal wage dispersion as equitable. In decentralized firms, there is more delegation of responsibilities to employees at lower levels in the hierarchy, creating more room for individual differentiation in terms of contributions and thus legitimizing horizontal wage dispersion. Our empirical analysis based on matched employer–employee data from Denmark strongly supports our predictions. Our study reveals the organizational contingencies where horizontal wage dispersion can be used as a retention tool.

The penetration phenomenon of the expiratory airflow from thermal plume of human body in the microenvironment around people

Understanding the influence of the human body's thermal plume on exhaled airflow is crucial for accurately assessing indoor infection risks. This study employs numerical simulations and a jet integral modeling method to investigate the airflow dispersion patterns of a single thermal manikin during sustained expiration. It was found that the thermal plume formed a two-stage evolution in exhaled airflow. Initially, the airflow was weakened by the thermal plume in the horizontal dispersion, and subsequently it was bent due to the entrainment of the surrounding air in the upward dispersion of the exhaled airflow. The thermal plume changes the trajectory and lateral dispersion distance of exhaled airflow. When the exhalation velocity is 1 m/s, the airflow is fully deflected towards the head plume region. When the exhalation velocity is between 1.5 and 2 m/s, the airflow is partially deflected, with only part of the upper airflow deflected towards the head plume region. In addition, it is interesting to note that the plume changes the dispersion trajectory of the exhaled airflow, while still adhering to the distributions of buoyant jet flow. This study suggests that the thermal effect of the human body is a significant factor in characterizing the dispersion of exhalation airflow and aerosols. Considering the thermal plume in indoor infection risk assessment is expected to yield more reliable data for theoretical modeling of respiratory airflow transport.

An In-Depth Investigation of Micropillar Array Columns for the Separation of Finite-Sized Particles by Hydrodynamic Chromatography.

The exact moment approach (EMA) is adopted to predict, without any fitting parameters, the plate height curves for polystyrene microparticles of different sizes in micropillar array columns performed by hydrodynamic chromatography. The EMA allows us to decouple the contribution of horizontal and vertical dispersion terms and thus investigate the influence of pillar height and interpillar distance on separation performance. In the convection-controlled regime, we found that axial dispersion is mainly controlled by the vertical dispersion term, the latter being due to the flow-arresting top and bottom walls. This vertical contribution can be estimated from the axial dispersion in rectangular, open tubular channels formed between the pillars. Henceforth, plate height curves can be accurately predicted by simply adding the estimated vertical term to the horizontal dispersion term evaluated from 2D simulations. This finding allowed us to understand that, to improve separation performance, it is advisible to decrease the interpillar distance (expected result) and decrease the pillar height (counterintuitive result).

Aeolian desert dust as a primary estuarine sediment source: Fine sediment transport and dynamics in the northern Arabian/Persian gulf

Fluvial discharge and freshwater runoff are recognized as the main sediment sources in many estuaries worldwide. Precipitation is, however, limited in arid and semi-arid areas, allowing for high aeolian dust activity, and inducing limited river runoff. As such, aeolian dust could contribute to the estuarine sediment sources in such areas. Uniquely, the Northern Arabian/Persian Gulf (NG) is continuously loaded with vast amounts of aeolian desert dust annually. This study focuses on the role of desert dust in the distribution of suspended sediment in the Northern Arabian/Persian Gulf (NG), employing in-situ measurements of physical parameters (collected in 2015–2016), satellite imagery, and a flexible mesh hydrodynamic model (Delft3D-FM) coupled with a sediment transport model (Delft-WAQ). The model showed reasonable performance in representing the complex system of NG. The study revealed that more than 90% of the sediment along the NG is aeolian dust, with the remaining being fluvial. Owing to salinity-induced density gradients, estuarine circulation keeps the fluvial sediment confined to the estuarine zone of the Shatt Al-Arab even during the events of increased freshwater discharges. In the NG most of the suspended sediments have an aeolian origin. They were found in shallow zones within the 5 m isobath, including the estuary of Shatt Al-Arab where they are mixed with the fluvial sediment fractions. Tides were found to play a key role in sediment mixing and horizontal dispersion in the shallow area of the NG most of the time, while the Shamal increased the transport of fine sediment to offshore areas (seaward). Based on current knowledge, this study represents a rare instance where estuarine sediment dynamics are primarily governed by aeolian deposits from a nearby desert.

Numerical Modelling and Prediction of Oil Slick Dispersion and Horizontal Movement at Bornholm Basin in Baltic Sea

This paper presents an original approach to predicting oil slick movement and dispersion at the water surface. Special emphasis is placed on the impact of evolving hydro-meteorological conditions and the thickness of the oil spill layer. The main gap addressed by this study lies in the need for a comprehensive understanding of how changing environmental conditions and oil thickness interact to influence the movement and dispersion of oil slicks. By focusing on this aspect, this study aims to provide valuable insights into the complex dynamics of oil spill behaviour, enhancing the ability to predict and mitigate the environmental impacts of such incidents. Self-designed software was applied to develop and modify previously established mathematical probabilistic models for predicting changes in the shape of the oil trajectory. First, a semi-Markov model of the process is constructed, and the oil thickness is analysed at the sea surface over time. Next, a stochastic-based procedure to forecast the horizontal movement and dispersion of an oil slick in diverse hydro-meteorological conditions considering a varying oil layer thickness is presented. This involves determining the trajectory and movement of a slick domain, which consists of an elliptical combination of domains undergoing temporal changes. By applying the procedure and program, a short-term forecast of the horizontal movement and dispersion of an oil slick provided its trajectory at the Bornholm Basin of the Baltic Sea within two days. The research results obtained are preliminary prediction results, although the approach considered in this paper can help responders understand the scope of the problem and mitigate the effects of environmental damage if the oil discharge reaches sensitive ecosystems. Finally, further perspectives of this research are given.

The relationship between December haze pollution in the Sichuan Basin and preceding climate factors

AbstractHaze pollution (HP) is one of the most serious disasters in the Sichuan Basin (SCB), adversely affecting human health, transportation, tourism and agriculture. HP in December is severe and differs from the haze days in January and February in terms of their temporal variations. To improve the understanding of December haze days in the SCB (DHDSCB), this study not only shows the atmospheric circulations and local meteorological circumstances related with the haze variation, but also analyses its relationship with the prior atmospheric apparent heat source over the Tibetan Plateau (TP) and the sea surface temperature (SST). The key circulation system associated with the interannual variation of the DHDSCB is that the SCB is controlled by the positive geopotential height anomalies and anomalous anticyclonic circulations with weak southwestward water vapour transport. Moreover, unfavourable local meteorological circumstances limit the vertical (horizontal) dispersion of pollutants. In addition, the DHDSCB during 1981–2022 is also found to have significant relationships with two preceding climate factors, which are the atmospheric apparent heat source (Q1) over the western TP in preceding November and the SST difference between the western Maritime Continent and western Australia in preceding autumn. The enhancement of Q1 over the western TP in preceding November is closely related to the midlatitude North Atlantic–southern Mediterranean Middle East–Arabian Sea–TP and its downstream region teleconnection pattern. Consequently, the anticyclonic circulation prevails over the SCB, and SCB is with less precipitation and more haze days in December. The western Maritime Continent and western Australia SST pattern in preceding Autumn is correlated with the Bay of Bengal–eastern TP and its downstream–Japan–Bering Sea teleconnection pattern, providing unfavourable moisture condition for the precipitation over the SCB and leading to the onset, development and maintenance of static weather in December. Therefore, the Q1 over the western TP and the SST pattern over the western Maritime Continent and western Australia may be potential indicators for the subseasonal prediction of HP in the SCB in December.

Salt intrusion dynamics in a well-mixed sub-estuary connected to a partially to well-mixed main estuary

Abstract. Salt intrusion in estuaries has been exacerbated by climate change and human activities. Previous studies have primarily focused on salt intrusion in the mainstem of estuaries, whereas those in sub-estuaries (those that branch off their main estuaries) have received less attention. During an extended La Niña event from 2021 to 2022, a sub-estuary (the East River estuary) alongside the Pearl River estuary, China, experienced severe salt intrusions, posing a threat to the freshwater supply in the surrounding area. Observations revealed that maximum salinities in the main estuary typically preceded spring tides, exhibiting significant asymmetry in salinity rise and fall over a fortnightly timescale. In contrast, in the upstream region of the sub-estuary, the variation in salinity was in phase with that of the tidal range, and the rise and fall of the salinity were more symmetrical. Inspired by these observations, we employed idealized numerical models and analytical solutions to investigate the underlying physics behind these behaviors. It was discovered that under normal dry conditions (with a river discharge of 1500 m3 s−1 at the head of the main estuary), the river–tide interaction and change in horizontal dispersion accounted for the in-phase relationship between the salinity and tidal range in the upstream region of the sub-estuary. Under extremely dry conditions (i.e., a river discharge of 500 m3 s−1 at the head of the main estuary), salinity variations were in phase with those of the tidal range in the middle as well as the upstream region of the sub-estuary. The variation in salinity in the main estuary along with those in salt dispersion and freshwater influx inside the sub-estuary collectively influenced salinity variation in the well-mixed sub-estuary. These findings have important implications for water resource management and salt intrusion prevention in the catchment area.

Shear horizontal wave dispersion in two phase magneto-electro-elastic material loaded with viscoelastic fluid layer

In the present work, an exact analytical approach has been used to study the dispersive behavior of the shear horizontal (SH) wave in magneto-electro-elastic (MEE) material loaded with a viscoelastic fluid. Complex dispersion equations are derived in the cases of electric short magnetic short (ESMS), electric short magnetic open (ESMO), electric open magnetic short (EOMS), and electric open magnetic open (EOMO) boundary conditions by solving the equilibrium equations of MEE material and the Stokes equation of viscoelastic fluid. To validate the present outcomes, the MEE material is changed into piezoelectric and piezomagnetic materials by taking some theoretical assumptions and the outcomes are matched with preexisting results. Effect of volume fraction, wave frequency, substrate thickness and thickness of the fluid layer on phase velocity and attenuation of SH wave have studied. This study may find its applications in better understanding of the surface acoustic wave devices incorporated with viscoelastic fluid layer.

Radiative impacts of the Australian bushfires 2019–2020 – Part 2: Large-scale and in-vortex radiative heating

Abstract. Record-breaking wildfires ravaged south-eastern Australia during the fire season 2019–2020. The intensity of the fires reached its paroxysmal phase at the turn of the year 2019–2020, when large pyro-cumulonimbi developed. Pyro-convective activity injected biomass burning aerosols and gases in the upper-troposphere–lower-stratosphere (UTLS), producing a long-lasting perturbation to the atmospheric composition and the stratospheric aerosol layer. The large absorptivity of the biomass burning plume produced self-lofting of the plume and thus modified its vertical dynamics and horizontal dispersion. Another effect of the in-plume absorption was the generation of compact smoke-charged anticyclonic vortices which ascended up to 35 km altitude due to diabatic heating. We use observational and modelling description of this event to isolate the main vortex from the dominant Southern Hemispheric biomass burning aerosol plume. Entering this information into an offline radiative transfer model, and with hypotheses on the absorptivity and the angular scattering properties of the aerosol layer, we estimate the radiative heating rates (HRs) in the plume and the vortex. We found that the hemispheric-scale plume produced a HR of 0.08±0.05 K d−1 (from 0.01 to 0.15 K d−1, depending on the assumption on the aerosol optical properties), as a monthly average value for February 2020, which is strongly dependent on the assumptions on the aerosol optical properties and therefore on the plume ageing. We also found in-vortex HRs as large as 15–20 K d−1 in the denser sections of the main vortex (8.4±6.1 K d−1 on average in the vortex). Our results suggest that radiatively heated ascending isolated vortices are likely dominated by small-sized strongly absorbing black carbon particles. The hemispheric-scale and in-vortex HR estimates are consistent with the observed ensemble self-lofting (a few kilometres in 4 months) and the main isolated vortex rise (∼ 20 km in 2 months). Our results also show evidence of the importance of longwave emission in the net HR of biomass burning plumes.

Modeling the Air Pollution and Aerosol‐PBL Interactions Over China Using a Variable‐Resolution Global Model

AbstractModeling air quality has always been a challenge in global models constrained by coarse grids. Here, the variable‐resolution Community Atmosphere Model with full chemistry based on the scalable spectral element (SE) dynamical core (MUSICAv0) is applied in simulating air pollution with a finer grid resolution of ∼0.25° over East Asia (SE_VR), in contrast to the same model with a uniform resolution of ∼1.0° (SE_UR). Two nudging experiments and four free‐running experiments are conducted to investigate the capabilities of SE_VR in modeling the air pollution and aerosol‐planetary boundary layer (PBL) interactions over China. Results show the regional refinement in SE_VR is essential for simulating haze events over complex terrain areas attributed to its better performance in representing the local vertical and horizontal dispersion conditions. SE_VR shows prominent advantages over SE_UR in simulating surface ozone because of better resolving spatial segregation of NOx and volatile organic compounds (VOC) chemical regimes and subsequently representing more detailed chemical processes related to ozone formation, although the model generally overestimates surface ozone over China. Further analysis of SE_VR shows the daytime radiative effect of black carbon (BC) aerosols lowers PBL height by 12.0% (17.9%), and leads to an increase of PM2.5 by 14.5% (10.8%) under the moderate (severe) air pollution conditions over Sichuan Basin. However, SE_UR has deficiencies in simulating BC‐PBL interactions due to its inability to reproduce the strong inverse temperature structure caused by BC aerosols in the lower atmosphere layer. Our results highlight the value of variable‐resolution global models for simulating air pollution and its interactions with climate.

Development of a Marine Radioactivity Expert System based on the Extended Marine Food Web: Experiments with Initial Bottom Contamination

An extended version of an expert system was developed as an effort to provide technical support to decision makers for the initial prompt assessment of environmental impacts of marine radioactivity, considering both pelagic and benthic marine food webs. The preliminary version of this system was firstly developed to determine the transfer of radionuclides through a pelagic marine food web (Kim et al, 2020). This system's approach was similar to the Cornell Mixing Zone Expert System (CORMIX) developed by Jirka (1995), as it used idealized settings for the physical/hydrodynamic coastal conditions. Existing or extended systems were executed by taking into account different kinds of radioactivity sources. The initial contamination of bottom sediment is considered in the present study, while the direct discharge to the coastal ocean from the nuclear power plant was considered in the early study. Assuming initial contamination, sensitivity experiments of temporal <sup>137</sup>Cs variations without/with horizontal advection and diffusion (EXP-WOHAD and EXP-WHAD, respectively) were conducted. In EXP-WOHAD, a total of six test cases were constructed, considering a range of vertical diffusion coefficients and sediment fluxes at the water-sea bed interface. The EXP-WHAD experiments were classified into two categories with six cases each, considering the horizontal diffusion and advection processes. The EXP-WOHAD results show that the vertical diffusion processes in the bottom sediment result in the exponential decay of the <sup>137</sup>Cs concentrations in the top sediment layer through upward and downward diffusive fluxes, producing pulse-like time variations in <sup>137</sup>Cs in the water column and the middle sediment layer. These sediment fluxes affect the peak height and its occurrence time in the water column and the middle sediment layer. From EXP-WHAD, it has been confirmed that part of <sup>137</sup>Cs diffused into the water column experiences horizontal dispersion and thereafter deposition to the bottom sediment. It is noted that due to the limited diffusion to the water column, the <sup>137</sup>Cs concentrations in benthic organisms are larger than those in pelagic organisms.

CFD simulation of gas dispersion at hydrogen bunkering station

ABSTRACT This research is to simulate hydrogen leakage at bunker station with various wind directions and velocities using Computational Fluid Dynamics (CFD) model to understand hydrogen dispersion behaviour and provide general guidelines to establish risk prevent measures and mitigations at early design phase. This case study examines hydrogen plume behavior in various wind conditions, focusing on horizontal and vertical dispersion as well as mean travel distance over time. Regardless of wind direction, hydrogen disperses in alignment with the wind. As time progresses post-leakage, the plume elongates in the wind's longitudinal direction and contracts vertically, maintaining a consistent shape. Wind direction and the direction of hydrogen release notably influence dispersion patterns. When the wind aligns vertically with the release point, hydrogen plume distance increases with higher wind speeds. Conversely, when wind opposes the release direction, plume length tends to decrease at high speeds. Intriguingly, the maximum distance of 27.85 m occurs when wind and leak directions are orthogonal at 180°. For wind speeds up to 5 m/s, all wind directions show a similar increase in plume distance. However, at 7 m/s, scenarios with horizontal, perpendicular wind directions exhibit a distinct change. Analyzing hydrogen dispersion aids in establishing safety criteria and risk mitigation distances for hydrogen leakages in bunker stations during the early design phase.

Simplified dispersion analysis based on dye tests at a small stream

Abstract The modelling of solid transport in open channels requires good knowledge about parameters related to basic processes such as hydrodynamic dispersion, advection and decay rates. Such parameters are usually determined by dye tests. Numerous tracer studies have been performed on laboratory flumes and natural rivers. However, on-site sampling is often difficult, expensive and needs special apparatus. The main aim of the study was to justify simplified method based on the monitoring of the dye cloud shape in order to determine both longitudinal and transversal dispersion coefficients. In this study, four dye tests were carried out on a small local stream (the Lipkovsky) using Rhodamine WT fluorescein dye as a tracer. The tests were carried out in such a manner that both longitudinal and horizontal transversal dispersion data were obtained. For this purpose, the visually determined extent of the dye cloud was interpreted via the analytical solution of the advection-dispersion equation. The results obtained by this simplified approach indicated that the longitudinal dispersion coefficient Dx = 0.051–0.057 m2/s and the coefficient of horizontal transversal dispersion Dy = 0.00024–0.00027 m2/s. The method was justified by corresponding root mean square error (RMSE) counting RMSE = 0.65–1.02 m for the dye cloud centre, RMSE = 1.87–2.46 m for the head and tail of the cloud and RMSE = 0.025–0.11 m for the cloud width, the Nash-Sutcliffe efficiency coefficients ranged from 0.9 to 0.998. The comparison of these values with empirical formulae and other tracer studies indicated significant overestimation of the mentioned values of Dx , which can be attributed to the uniform velocity distribution along the width of Lipkovsky Stream. Much better agreement was achieved for Dy .

The Influence of a Key Indicator kv on the Diffusion Range of Underwater Oil Spill

As oil spills cause harm to the survival and environment of the ocean, the objective of the present paper is to study the oil migration range using the key indicator kv, which is defined as the ratio of oil spill speed to ocean current speed. The correctness of diffusion models created and estimated for subsea oil spills can be verified by experiments. We also considered the effect of key indicators on the horizontal and vertical dispersion ranges of oil spills. The study’s findings show that, under various kv settings, the horizontal and vertical spreading heights of oil spills both increase as kv rises. When kv is equal, the leakage velocity and water flow velocity increase synchronously, and over time, the horizontal distance and vertical diffusion height of the oil spill gradually increase. In the early stages of an oil spill, when kv = 50, 100, or 150, the vertical spreading velocity will rapidly decrease. The vertical spreading speed of spilled oil increases as kv rises when the water flow rate remains constant. The horizontal migration distance grows as kv decreases when the leakage rate is constant. Fitting curves for the vertical rise height and horizontal spreading distance for the same and various kv settings were also obtained in order to anticipate the migration mode of oil spills. This is critical for dealing with environmental damage caused by maritime oil spills, as well as emergency responses.

The Non-linear Relationship between Horizontal Pay Dispersion and Technological Knowledge Production

The Non-linear Relationship between Horizontal Pay Dispersion and Technological Knowledge Production

Spatial and temporal dispersion of Doryctobracon areolatus (Szépligeti) (Hymenoptera: Braconidae) in orchards infested with Anastrepha fraterculus (Wiedemann) (Diptera: Tephritidae).

Doryctobracon areolatus (Szépligeti) is an endoparasitoid and promising fruit fly control agent. The objective of the study was to determine the spatial (horizontal and vertical) and temporal dispersion of D. areolatus in the field. To evaluate the horizontal and temporal dispersion, two peach orchards were selected. In each orchard, 50 points were marked at different distances from the central point, from where 4,100 couples of D. areolatus were released. Four hours after release, parasitism units (PU) (3 per point) were fixed to the trees at a height of 1.5 m from the ground. The PUs were composed of ripe apples artificially infested with second instar larvae of Anastrepha fraterculus (30 larvae/fruit). For the evaluation of vertical dispersion, in an olive orchard six points were selected (trees of ≈4 m in height). Each tree was divided into three heights in relation to the ground (1.17, 2.34, and 3.51 m). Doryctobracon areolatus was able to disperse horizontally at a distance >60 m from the release point. However, the highest parasitism rates [15-45% (area 1); 15-27% (area 2)] were observed up to 25 m. Higher percentages of parasitism and of recovered offspring occur in the first days after the release of the parasitoid (2 DAR). As for vertical dispersion, D. areolatus parasitized A. fraterculus larvae up to the highest attachment height of the evaluated PUs (3.51). The results showed the potential use of D. areolatus in the management of fruit flies in the field.