Modelling of hydrodynamics and mecury transport in lake Velenje. Part 2, Modelling and model verification

PCFLOW3D - a three-dimensional mathematical model that was developed at the Chair of Fluid\ud Mechanics of the Faculty of Civil and Geodetic Engineering, University of Ljubljana, was used for\ud hydrodynamic and Hg transport simulations in Lake Velenje. The model is fully non-linear and\ud computes three velocity components, water elevation and pressure. Transport-dispersion equations\ud for salinity and heat (and/or any pollutant) are further used to compute the distributions of these\ud parameters. The results show that the major sources of mercury in Lake Velenje are lake inflows.\ud The hydrodynamic simulations revealed that ground and/or surface water inflow and outflow do not\ud have much influence on water cycling in the lake basin. Wind and ambient temperature seem to\ud have the greatest influence on water movement in the lake. Mercury transport simulations\ud performed by PCFLOW3D show good agreement with the measured distribution of different Hg\ud and MeHg forms in Lake Velenje. Verification of water flow was done by isotope tracers δ18O and\ud δ2H and measurements of different Hg and MeHg forms. Distribution of different Hg species and\ud forms and isotopic composition in water of Lake Velenje is described in Part 1

Limitation and Restrictions on the Admission of Postpanamax Container Ships in the Port of Koper

The recent global container transport increase amounts to about 8-10% on a yearly basis - in the Port of Koper in 2012 it was 570,744 TEU, which brings Koper\u27s increase to 850% over the last 15 years. Despite the global recession, the decline in container transport in 2009 was minimal. A great increase in transport followed in the year 2010 which was partly a consequence of the introduction of a direct line between Asia and the north Adriatic. Further increases in container traffic depend primarily on the technological readiness of the Port of Koper. Therefore, it is necessary to invest in transport mechanization and hinterland connections, but also to provide sufficient draught and a properly shaped channel to ensure a safe approach for larger container vessels calling at the Port of Koper. The paper presents statistics and methods supporting container terminal enlargement and a safety and environmental assessment derived from the use of a ship handling simulator with specific consideration given to th

Prerequisites for the development of mass balance models of the biogeochemical cycle of mercury in the Mediterranean Sea

The information presently available on the biogeochemical cycle of mercury in the Mediterranean Sea is reviewed in an attempt to evaluate our state of knowledge, to pinpoint gaps in our understanding and to assess the possibility of establishing mass balance models. The need to promote such models for either the large scale Mediterranean system or individual small scale coastal basins have been discussed. The basic requirements to facilitate the development of mass balance models for both scales were identified.peer-reviewe

Limitation and Restrictions on the Admission of Postpanamax Container Ships in the Port of Koper

The recent global container transport increase amounts to about 8-10% on a yearly basis - in the Port of Koper in 2012 it was 570,744 TEU, which brings Koper\u27s increase to 850% over the last 15 years. Despite the global recession, the decline in container transport in 2009 was minimal. A great increase in transport followed in the year 2010 which was partly a consequence of the introduction of a direct line between Asia and the north Adriatic. Further increases in container traffic depend primarily on the technological readiness of the Port of Koper. Therefore, it is necessary to invest in transport mechanization and hinterland connections, but also to provide sufficient draught and a properly shaped channel to ensure a safe approach for larger container vessels calling at the Port of Koper. The paper presents statistics and methods supporting container terminal enlargement and a safety and environmental assessment derived from the use of a ship handling simulator with specific consideration given to th

Long-term scenarios of mercury budgeting and exports for a Mediterranean hot spot (Marano-Grado Lagoon, Adriatic Sea)

The Marano-Grado Lagoon (MGL) is extensively contaminated by mercury (Hg) from local sources and long-term (500 years) tidally delivered inputs from the Idrija Hg mine (Slovenia) through Isonzo River suspended loads. A multibox WASP-7 (Water Analysis Simulation Program) model was used to simulate the long-term dynamics of the mercury cycle in the MGL. Scenario simulations were used to compute changes in the system over 100 years. Present and future Hg concentrations in water, sediment, and Hg budgets were compared, including evasion and MeHg inputs to the Mediterranean Sea, based on climate changes and mercury capping in tributary rivers. Using the Ref baseline scenario, the model computes a general decrease in HgT of 13% in the water column and of 80% in sediment and a strong MeHg increase in sediment (+73%). The net sea export of HgT decreases by 77% to up to 48 kg/y while MeHg increases by 10% to up to 0.63 kg/y. The lagoon sediment recovery time of HgT up to a target level of 0.3 mg/kg is computed over 570 years for surface sediments (1750 for subsurface sediments). When removing Hg from boundaries, the same target value for surface sediments is reached within 110 years

A comparison of the MIKE 3 and PCFLOW3D models for hydrodynamic simulations in the Gulf of Trieste

A comparison between the hydrodynamic simulations of the models MIKE 3 and\ud PCFLOW3D in the Gulf of Trieste was performed.\ud The model MIKE 3 was developed at the Danish Hydraulic Institute (DHI). It is used to\ud simulate three-dimensional free-surface flow. At the Chair of Fluid Mechanics a similar\ud model PCFLOW3D is being developed and practically used since 1985. This model is used to\ud study processes in larger water bodies, such as lakes and seas, where the horizontal velocities\ud are larger than vertical for an order of magnitude. The basic characteristics of both models are\ud presented in this work.\ud The input data and a comparison of the results of some simulations performed in the Gulf of\ud Trieste with both models is further shown. Geometry and bathymetry data, temperature and\ud salinity conditions in the Gulf of Trieste and at the Soĉa river mouth, wind velocity and\ud direction as well as discharge and velocity of the River Soĉa were required for the\ud simulations. Realistic seasonal conditions were simulated using different turbulence models.\ud In the vicinity of the Soĉa river mouth a comparison of the results was performed also for a\ud refined numerical grid. The agreement of results was better in winter conditions (bora wind),\ud while simulations of tidal forcing and in summer conditions showed worse agreement of the\ud results.\ud The results of both models are comparable, despite relatively high discrepancies in some parts\ud of the modelling domain. Minor differences in numerical schemes and turbulence models\ud offered by both models and different input of boundary conditions, particularly at the open\ud boundary and in the inflow cell, were found to be the main reasons of discrepancies

Modelling of mercury exchange between sediment and water in the gulf of Trieste

The present work focuses on modelling of mercury exchange between sediment and water due to diffusion using three-dimensional nonlinear unsteady-state baroclinic mathematical model PCFLOW3D. The PCFLOW3D model was upgraded with the equations for determining the diffusion fluxes of mercury between sediment and water on the basis of concentrations in sediment pore waters and in the overlying water. The performed model verification showed a good agreement between the results of simulations and the test calculations in Excel. In the performed sensitivity analysis the impact of all relevant parameters in the exchange equations (diffusion coefficient, sediment porosity, Hg concentrations in sediment and water, thickness of active sediment layer, and thickness of contaminated sediment) was evaluated. The results showed that for accurate simulations each individual parameter has to be chosen correctly.\ud The model was further used for simulations in the Gulf of Trieste, which, due to the lack of reliable input data only serve as an additional test of the model and do not represent the real situation. The performed simulations took into account 5, 10, 30 and 90 day time intervals, separately for summer and winter conditions. The results of simulations were compared to measurements in the Gulf of Trieste described in Covelli et al. (1999). The achieved agreement was within an order of magnitude. The quantity of mercury removed from the sediment within one year was further determined from simulations. The agreement within a factor of four was achieved with the published results.\ud The described approach of determining sediment-water diffusion fluxes was used in the PCFLOW3D model for the first time. With additional quality input data this approach will enable the improvement of the modelling results and better understanding of the mercury cycle in coastal seas.\ud \u

Hydraulic zonation of the lagoons of Marano and Grado, Italy. A modelling approach

The hydraulic regime-based zonation scheme of the Lagoons of Marano and Grado (Italy) has been derived by means of numerical models. A finite element modelling system has been used to describe the water circulation taking in account different forces such as tide, wind and rivers. The model has been validated by comparing the simulation results against measured water levels, salinity and water temperature data collected in several stations inside the lagoons. The analysis of water circulation, salinity and spatial distribution of passive tracers released at the inlets, led to a physically-based division of the lagoons system into six subbasins. The derived classification scheme is of crucial value for understanding the renewal capacity and pollutants distribution patterns in the lagoon

Parameters affecting the presence of methyl-mercury in the water column of the Mediterrranean sea

The thesis presents parameters affecting the presence of methyl-mercury (MeHg) in the water column of the Mediterranean Sea. The area is polluted with mercury due to a wide variety of sources stemming from the cinnabar belt underlying the Mediterranean from Spain to Turkey, where the most of the world mercury stock can be found. Mercury is transported through the air and rivers into marine environment. Numerous parameters that affect the concentrations of methyl-mercury and the methylation in the water column (microbial activity, temperature, pH, organic matter, redox conditions, sulfide, and salinity) are still not clarified. These parameters are described in detail on the basis of available literature. Several analyses were performed on data obtained in the framework of the MERCYMS and MED-OCEANOR projects in order to investigate possible connections between environmental parameters, concentrations, and transformation coefficients of mercury in marine environment. Such a parameterisation and possible new reaction coefficients would represent a valuable tool in modelling of mercury methylation and demethylation in the water column. Correlation coefficients were extremely low in all performed analyses (< 0.5); therefore, it was not possible to establish any connections between the measured environmental parameters and the concentrations of methyl-mercury from the obtained trendlines. Seasonally averaged concentrations within different layers and parts of the Mediterranean Sea showed elevated concentrations of MeHg in the Adriatic Sea, and higher MeHg concentrations at the sea-bottom in the autumn, which is consistent with previously published research studies