A universal nutrient application strategy for the bioremediation of oil-polluted beaches

Biostimulation by nutrient application is a viable technology for restoring oil-contaminated beaches. Maximizing the nutrient residence time is key for achieving a rapid cost-effective cleanup. We considered the nutrient injection strategy through a perforated pipe at the high tide line and we simulated numerically beach hydraulics, which allowed us to estimate the optimal injection flow rate of nutrient solution. Our results indicate that the optimal application is one that starts following the falling high tide and lasts for half tidal cycle. The saturated wet-front of the nutrient solution on the beach surface would move seaward with the same speed of the falling tide keeping a constant distance with the tide line. The numerical results were generalized to beaches of wide ranges of hydraulic and tidal properties using a novel dimensionless formulation for water flow and solute transport in porous media. Nomographs were presented to provide the flow rate based on four parameters: The beach slope and hydraulic conductivity, and tidal amplitude and period.     

Natural headland control of beaches

When waves arrive obliquely to a coast they cause littoral drift, the fluctuations of which result in cycles of erosion and siltation. These are minimised when the resultant wave energy is normal to the beach as the longshore component of energy approaches zero. This situation occurs naturally when headlands exist and the shoreline between them is sculptured into zeta shaped bays with logarithmic spiral plan shape. Waves are then diffracted and refracted into the embayment, arriving at the beach more normally. There is a limiting erosive pattern, for the case of no further input of sediment, where the log spiral and indentation ratio reach values which are predictable. These can then be used to test the stability of that section of coast.     

Near shore waves,long-shore currents and sediment transport along micro-tidal beaches,central west coast of India

Coastlines are undergoing constant geomorphologic changes with respect to the incident wave climate.Based on waves measured at 9 m water depth,simulation of near shore wave transformation is done using REFDIF-1numerical model and the near shore breaker parameters are estimated at two micro-tidal beaches along central west coast of India.Model results are validated with measured values.From the breaker parameters,long-shore current and long-shore sediment transport rates（LSTR） are computed by using semi-empirical equations.Estimated long-shore current and LSTR are showing dramatic variations with respect to seasons.Predominant direction of LSTR is observed towards north since the approach waves are from south-west direction during pre-monsoon and post monsoon.During monsoon season,waves are from west south-west and resulted in southerly transport.The estimated annual net and gross LSTR by Cambridge Environmental Research Consultants（CERC） at two locations are in the same order whereas LSTR estimated by Walton ＆ Bruno and Kamphuis equations are showing different estimations because of difference in surf-zone width and foreshore slope between the two locations.For micro-tidal beaches with length less than 6 km,Kamphuis equation is giving agreeable estimation of LSTR.Sensitivity analysis of LSTR estimate shows that coastal inclination is the prominent factor in determining LSTR than incident wave angle.     

Effects of oil on water filtration by exposed sandy beaches

The most important natural function of exposed sandy beaches is the filtration of large volumes of sea water which are flushed through the interstitial pore system by the actions of tides and waves. In this process organic material is mineralized by the interstitial fauna and nutrients returned to the sea. This paper examines the physical effects of oil in blocking or reducing this filtration. Reduced filtration of sea water may be caused by prevention or retardation of interstitial water flow and/or decrease in pore space. The magnitude of the effects depends on the volume of oil, its state of weathering, its location on the beach and its degree of admixture with sand. It appears that under all but the heaviest conditions of pollution these effects are relatively small and only become significant in situ when discrete layers of weathered oil occur near the surface in the upper intertidal zone where maximum water input normally occurs.     

The macroinfauna of the Galician sandy beaches (NW Spain) affected by the Prestige oil-spill

Eighteen sandy beaches were sampled along the 1659 km of the Galician coast (NW Spain) six months after the Prestige oil-spill to study the impact of the fuel and the clean-up activities on the macroinfauna community. A transect was extended at each beach, from above the drift line to below the swash line at five sampled levels; at each level six 0.05 m2 replicates were taken to a depth of 30 cm and sieved through a 1mm mesh, and the organisms collected and preserved. Results were compared with previous data obtained using the same procedures. The macroinfauna was numerically dominated by the amphipod Pontocrates arenarius, the isopod genus Eurydice, the polychaete Scolelepis squamata, and the amphipod Talitrus saltator. As a result of the Prestige oil-spill and the clean-up activities, beach populations were reduced, with Eurydice and S. squamata as the most affected taxa.     

On resonant over-reflection of waves by jets

It is well known that internal or Rossby waves propagating across a jet can be amplified, a phenomenon usually referred to as over-reflection. In some cases, over-reflection can be infinitely strong – physically, this means that the reflected and transmitted waves can exist without an incident one, i.e. they are spontaneously emitted by the mean flow. In this article, it is shown that infinitely strong over-reflection (resonant over-reflection) occurs for gravity-wave scattering by ageostrophic jets in a rotating barotropic ocean and Rossby-wave scattering by a two-jet configuration on the quasigeostrophic beta-plane. It is further demonstrated that, generally, a resonantly over-reflected wave is always marginal to instability, i.e. either an increase or a decrease of its wavenumber transforms it into an unstable eigenmode localised near the jet.     

Microbial community of cyanobacteria mats in the intertidal zone of oil-polluted coast of Saudi Arabia

Cyanobacterial mats are found at various locations along the coast of the Eastern Province of Saudi Arabia. Those mats were affected by severe oil pollution following 1991 oil spill. In this study, samples from Abu Ali Island were collected at three selected sampling sites across the intertidal zone (Lower, Middle, and Upper) in order to understand the effect of extreme environmental conditions of high salinity, temperature and desiccation on distribution of cyanobacteria along the oil polluted intertidal zone. Our investigation of composition of cyanobacteria and diatoms was carried out using light microscopy, and Denaturant Gradient Gel Electrophoresis (DGGE) technique. Light microscopy identification revealed dominant cyanobacteria to be affiliated with genera Phormidium, Microcoleus, and Schizothrix, and to a lesser extent with Oscillatoria, Halothece, and various diatom species. The analysis of DGGE of PCR-amplified 16S rRNA fragments showed that the diversity of cyanobacteria decreases as we proceed from the lower to the upper intertidal zone. Accordingly, the tidal regime, salinity, elevated ambient air temperature, and desiccation periods have a great influence on the distribution of cyanobacterial community in the oil polluted intertidal zone of Abu Ali Island.     

Daily accumulation rates of marine debris on sub-Antarctic island beaches

The worlds’ oceans contain a large but unknown amount of plastic debris. We made daily collections of marine debris stranded at two sub-Antarctic islands to establish (a) physical causes of strandings, and (b) a sampling protocol to better estimate the oceans’ plastic loading. Accumulation rates at some beaches were dependent on tide and onshore winds. Most of the 6389 items collected were plastic (Macquarie 95%, Heard 94%) and discarded or lost fishing gear comprised 22% of those plastic items. Stalked barnacles (Lepas spp.) were a regular attachment on Macquarie debris but not at Heard Island. The daily accumulation rate of plastic debris on Macquarie Island was an order of magnitude higher than that estimated from monthly surveys during the same 4 months in the previous 5 years. This finding suggests that estimates of the oceans’ plastic loading are an order of magnitude too low.     

Scattering of rossby waves by partial barriers

Abstract

The scattering of Rossby waves by partial barriers is studied. It is found that only a small fraction of the wave energy will penetrate the gap between South America and Antarctica if the wave period is less than a month.     

Generation of waves by advected pressure fluctuations

Abstract

Because of the dispersion of surface gravity waves, the rate at which advected pressure fluctuations generate wave energy is independent of the coherence time of the pressure fluctuations provided that this time is long compared with the period of the waves. Phillips' (1957) analysis is correct insofar as it concerns wave components exactly “resonant” with the advected pressure fluctuations, but it does not deal adequately with the “bandwidth” of the resonance.     

Sand wave formation by stationary waves

In this paper we develop a new hypothesis which relates the formation of sand waves in open flow to the effect of stationary (lee) waves on flow with smooth nonhomogeneous downstream depth or behind an obstacle. The lee wave moves upstream with the phase velocity equal to the absolute value of the flow velocity, hence the wave crest does not move. Results of our experiments show that sand waves on the flow bed appear only below the lee waves and characteristics of sand waves are determined by the wave properties. We investigated the nonlinear stationary waves for subcritical and supercritical Froude numbers. These results allow us to predict sand waves characteristics for a particular flow.     

Resonance induced by Rossby Lee waves

Abstract

The mutual interaction of fields induced by spatially separated potential vorticity sources in a quasi-geostrophic barotropic flow is investigated using the weakly nonlinear approach. It is found that a powerful nonlinear response can be triggered by Rossby lee waves. This resonance phenomenon which dominates all other nonlinear corrections depends on certain global resonance conditions and on the change in the phase of the Rossby lee wave across the distance separating the sources. The response is particularly strong for topographic forcing possessing δ-function characterisitics.     

Kinematic dynamo induced by helical waves

We investigate numerically the kinematic dynamo induced by the superposition of two helical waves in a periodic box as a simplified model to understand the dynamo action in astronomical bodies. The effects of magnetic Reynolds number, wavenumber and wave frequency on the dynamo action are studied. It is found that this helical-wave dynamo is a slow dynamo. There exists an optimal wavenumber for the dynamo growth rate. A lower wave frequency facilitates the dynamo action and the oscillations of magnetic energy emerge at some particular wave frequencies.     

Sunglitter radiance modulation by internal waves

Summary Quantitative sunglitter radiance modulations at the ocean surface due to internal waves were calculated applying a simple first order theory. The results have been compared with the image data of internal wave signatures northeast of Nantucket Shoals off the coast of Massachusetts, U.S.A., taken by the Earth Terrain Camera (ETC) during the Skylab mission. The maximum magnitudes of sunglitter radiance modulations predicted by the theory are comparable to the satellite image data. The extreme values of calculated modulations depend only weakly on the wavelength of the internal wave signature. This is consistent with the analysed ETC data. On the other hand, the shapes of simulated and measured image intensity transects across an internal wave packet are different. This may possibly be explained by the assumed idealized sinusoidal type of thermocline used in the calculations. The theory predicts that sunglint signatures of internal waves are advected relative to positions of extreme slope regions of the thermocline due to currents.

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Strahldichtemodulation des Sonnenglitzerns durch interne Wellen

Zusammenfassung Quantitative Strahldichtemodulationen des Sonnenglitzerns an der Meeresoberfl?che durch interne Wellen werden unter Verwendung einer einfachen ersten Ordnungstheorie berechnet. Die Ergebnisse werden mit Bilddaten von internen Wellensignaturen nord?stlich von Nantucket Shoals vor der Küste von Massachusetts, U.S.A., verglichen, die w?hrend der Skylab-Mission von der Erdbeobachtungskamera (ETC) aufgenommen wurden. Die Werte der maximalen Strahldichtemodulation des Sonnenglitzerns, die von der Theorie vorhergesagt werden, sind mit den Satellitenbilddaten vergleichbar. Die Extremwerte der berechneten Modulationen h?ngen nur schwach von der Wellenl?nge der internen Wellensignaturen ab. Dieses stimmt mit den analysierten ETC Daten überein. Auf der anderen Seite sind die Kurvenverl?ufe zwischen den simulierten und gemessenen Bildintensit?tsprofilen entlang eines internen Wellenpaketes unterschiedlich. Dieses kann m?glicherweise durch den angenommenen idealisierten sinusf?rmigen Typ der Thermokline erkl?rt werden, der für die Berechnungen verwendet wurde. Die Theorie macht die Vorhersage, da? Signaturen des Sonnenglitzerns von internen Wellen durch Str?mungen advektiert werden relativ zu den Positionen der extremen Neigungsregionen der Thermokline.

     

The persistence and character of stranded oil on coarse-sediment beaches

Small amounts of oil that can persist for decades in the intertidal zone of coarse-sediment beaches have been documented in a few well-studied cases. Oil that survives attenuation over the short-term (weeks to months) will persist until there is a change in the environmental conditions, as might occur where there is a seasonal storm-wave climate or as a beach undergoes long-term (erosional) changes. Oil residues can persist on the beach surface as tar mats, asphalt-like pavements, or as veneers on sediment particles or hard surfaces. Subsurface oil residues can persist in similar forms or as fill or partial fill of the pore spaces between coarse-sediment particles. Oil penetrates until it reaches fine-grained sediment, the water table, bedrock, or other penetration-limiting layers. Amounts of persistent oil are very small fractions of the volumes that were originally stranded and these protected residues can continue to biodegrade as they become thinner and more discontinuous.     

Modelling the time-varying extent of groundwater seepage on tidal beaches

The outcrop of groundwater on tidal beaches distinguishes an upper unsaturated region from a lower saturated region of the intertidal profile. Since the 1940s, it has been recognized that the extent of groundwater seepage at the beach face is one factor determining the tendency for erosive or accretionary conditions to prevail. As a primary step towards incorporating bed saturation characteristics within cross-shore sediment transport models, this paper (and accompanying program disk) details a simple model to simulate the time-varying extent of seepage face development across tidal beaches. From a comparison with field results obtained on the macrotidal Central Queensland (Australia) coast, the model appears to provide an encouraging degree of predictive capability. The model also assists in highlighting the sensitivity of seepage face development to varying beach face, tide and wave characteristics.     

Shore litter along sandy beaches of the Gulf of Oman

Beach debris abundance and weight were estimated from surveys on 11 beaches of the Gulf of Oman along the Omani coast. Debris were collected on two occasions from 100 m transects, sorted and categorized by origin and type. Overall contaminations ranged from 0.43 to 6.01 items m(-1) of beach front on different beaches with a mean value of 1.79+/-1.04 gm(-1) (95% C.I). In terms of weight, contamination levels ranged from 7.8 to 75.44 gm(-1) of beach front with a mean contamination of 27.02+/-14.48 gm(-1) (95% C.I). In terms of numbers of items, plastic debris ranked first on all beaches followed by either wood items or other organic materials such as cigarette butts. Industrial debris remained few on all beaches (<10%). Most debris had a local origin and, in terms of numbers, were associated with beach recreational activities whereas fishing debris represented the largest proportion of the debris in terms of weight. There were notable differences between beaches in the relative abundance of recreation-related and fishing-related debris.     

The formation of beaches on shore platforms in microtidal environments

Beaches are common features of many rocky shorelines and can be considered to be constrained by the underlying geology. In mesotidal to macrotidal areas the slope of the substrate and sediment supply are the primary factors in constraining the size and development of beaches on shore platforms. In microtidal settings it is not known if these factors are wholly responsible for determining the presence of beaches on shore platforms, nor the contribution of other factors such as hydrodynamics. The microtidal coast of Victoria, Australia, is surveyed in this study in order to quantify the morphological boundary conditions that constrain beach development on semi‐horizontal shore platforms. An ample sediment supply indicates that the underlying geology is controlling the presence and absence of beaches. Where beaches occur they always overlie a rock ramp which is the steepest part of the platform. The two most important morphological constraints were platform width and height both of which significantly correlated with beach volume. An elevational threshold exists at just over +1.0 m where beaches cannot accumulate. Below this threshold, platform width appears to be the principle constraining factor in beach accumulation. An evolutionary model is inferred which suggests that dissipation of wave energy associated with platform widening plays an important role in allowing beaches to accumulate. The model suggests beaches on platforms will be particularly sensitive to sea level rise. Copyright © 2014 John Wiley & Sons, Ltd.