Search

In the Adriatic Sea (Mediterranean Sea), during monitoring of Production Water (PW) discharged from offshore platforms, high contamination levels of metals, PAH, and aliphatic hydrocarbons are detected in the sediment close to some installations. Here, we investigate for the first time, the transport and fate of the total suspended solids (TSS) associated with PW discharged by selected platforms, considering the separation of particulate matter from the water plume. We apply a 3D hydrodynamic model and a Lagrangian module to simulate the dispersion of PW suspended substances, then we relate the numerical results to the sediment contamination measured data. The TSS released with PW determines a negligible contribution along the water column and seems poorly related to the anomalies observed in the sediment contamination levels. This approach paves the way to assess the potential risks arising from TSS discharged with the PW on marine ecosystems and to optimize the environmental monitoring tools.

Surface gravity waves retrieved by a network of HF (High Frequency) radars and measured in situ by an ADCP (Acoustic Doppler Current Profiler) current meter connected to an elastic beacon were used to carry out a multiple-year characterization of the wave field of the Gulf of Naples (south-eastern Tyrrhenian Sea, western Mediterranean). The aim of the work was to create a climatology of the study area and to demonstrate the potential of an integrated platform for coastal studies. The patterns recorded by the different instruments were in agreement with the wave climatology of the southern Tyrrhenian Sea as well as with previous scores for the same area. The results presented in this work also highlight seasonal and interannual consistency in the wave patterns for each site. In a wider context, this study demonstrates the potential of HF radars as long-term monitoring tools of the wave field in coastal basins, and supports the development of integrated observatories to address large-scale scientific challenges such as coastal ocean dynamics and the impact of global change on the local dynamics.

The Gulf of Naples is a coastal area in the south-eastern Tyrrhenian Sea (western Mediterranean). Zones of great environmental and touristic value coexist in this area with one of the largest seaports in the Mediterranean Sea, industrial settlements and many other pollution sources. In such an environment, water renewal mechanisms are crucial for maintaining the ecological status of the coastal waters. In this paper, we focus on the water exchange between the interior of the Gulf and the neighbouring open Tyrrhenian Sea. The surface dynamics of the Gulf have been investigated based on measurements carried out with a high-frequency (HF) radar system. The vertical component of the current field has been provided by the Regional Ocean Modelling System (ROMS) model of ocean circulation. We present the results of a one-year-long analysis of data and simulation results relative to the year 2009. Inshore/offshore exchanges were assessed by looking at the zonal component of the surface and subsurface current field across a transect representing a sort of threshold between the interior of the Gulf and the open sea. This also allows for the reconstruction of the short-term origin of waters found inside the Gulf in the different forcing and circulation conditions.

The calanoid Clausocalanus furcatus and the cyclopoid Oithona plumifera are species dominating the copepod assemblage in oligotrophic environments but displaying contrasting swimming behaviour. C. furcatus moves almost continuously along very convoluted trajectories, while O. plumifera sinks slowly with occasional brief relocating jumps. To evaluate the efficiency of such opposing behaviour in encountering potential prey, the swimming performances of both species are here simulated with a Lagrangian, individual-based approach, implemented to simulate the realistic motion and perceptive fields of the two species. For each modelled swimming trajectory, we calculate the number of realised encounters and the associated search efficiency in uniform and patchy distributions of virtual prey. C. furcatus will perform better than O. plumifera in terms of realised encounters, but its search efficiency will be lower owing to the peculiar motion behaviour and to the shape and extension of the perceptive field. Despite these differences, these two species do co-exist in food diluted areas, thus indicating alternative strategies to successfully thrive in pelagic oligotrophic environments.

High-frequency coastal radars (HFRs) have proved to be excellent tools for monitoring coastal circulation, providing synoptic, high spatial and temporal resolution surface current data in real time...

An individual-based model is presented which describes the spatial and temporal evolution of phytoplankton growth in terms of a Lagrangian ensemble of cells affected by various physical and biological forcing factors. The motion of cells develops according to a turbulent velocity field which simulates the Antarctic mixed layer during the summer. The cell growth is a function of the irradiance regime, nutrient availability and the vertical position of the individual with respect to the other cells (in order to evaluate the self-shading effect). The values of photosynthetic parameters used to simulate the photophysiological response of the organisms are derived from measurements collected in the Ross Sea. In contrast to previous individual-based descriptions, all the physical and biological processes involved are explicitly reproduced in their dynamical features. Coupling different mixing levels with photoacclimation strategies leads to a wide range of photophysiological responses which underline the role of individual physiological histories in determining the growth of the population as a whole. Simulated photosynthetic parameters, chlorophyll a concentrations and integrated primary production correspond closely to in situ data and confirm that photoacclimation to low irradiance and strong mixing regimes may be considered as crucial factors in the photosynthetic performance of Antarctic phytoplankton.

Produced formation waters (PFWs), a by-product of both oil and gas extraction, are separated from hydrocarbons onboard oil platforms and then discharged into the sea through submarine outfalls. The dispersion of PFWs into the environment may have a potential impact on marine ecosystems. We reproduce the initial PFW-seawater mixing process by means of the UM3 model applied to offshore natural gas platforms currently active in the Northern Adriatic Sea (Mediterranean Sea). Chemical analyses lead to the identification of a chemical tracer (diethylene glycol) which enables us to follow the fate of PFWs into receiving waters. The numerical simulations are realized in different seasonal conditions using both measured oceanographic data and tracer concentrations. The numerical results show the spatial and temporal plume development in different stratification and ambient current conditions. The analytical approach measures concentrations of the diethylene glycol at a maximum sampling distance of 25 m. The results show a good agreement between field observations and model predictions in the near-field area. The integration of numerical results with chemical analyses also provides new insight to plan and optimize PFW monitoring and discharge.