N Zharova

A simulation model for the annual fluctuation of Zostera marina biomass in the Venice lagoon

Abstract A simulation model was built to describe the growth patterns of Zostera marina in an area in the Venice lagoon. The model tracks changes in the above- and below-ground biomass and shoot density and is based on data for Zostera biomass, net production and growth rates, chemical-physical parameters and nutrient concentrations in water, sediment and particulate matter. It was assumed that the most important factors controlling Zostera growth and distribution are light and temperature, and that Zostera growth was not limited by nutrient availability. The goal was to simulate biomass production and its seasonal changes as a function of external forcing variables (light, water temperature, wind and tide-generated water movements) and internal control (plant density). A series of simulation experiments were performed with the basic model and its modifications showed that among the most important phenomena affecting Zostera growth are: (1) inhibition of production and recruitment of new shoots by high temperature and (2) light attenuation due to seasonal fluctuation and wind- and tide-induced suspension of sediments.

ENVIRONMENTAL POLLUTANTS AND ORGANIC CARBON CONTENT IN SEDIMENTS FROM AN AREA OF THE MOROCCAN MEDITERRANEAN COAST

Toxicol.andEnviron.Chem., Vol. 84, No. 1–4, pp. 53–67 2001 OPA (Overseas Publishers Association) N.V.Reprints available directly from the publisher Published by license underPhotocopying permitted by license only the Gordon and Breach SciencePublishers imprint,a member of the Taylor & Francis Group.

Time trend of Butyl- and Phenyl-Tin contamination in organisms of the Lagoon of Venice (1999–2003)

In the period 1999–2003 a monitoring study on the accumulation of organotin compounds in edible organisms in the Lagoon of Venice was conducted. Butyl and Phenyl derivatives were determined in pooled samples of Mytilus galloprovincialis and Tapes spp. with the aims of assessing organotin contamination in the Lagoon of Venice in the period just preceding their ban in Europe, monitoring the concentrations in organisms with a high commercial use, evaluating a potential hazard for human health due to seafood and identifying the possible contamination sources. Sampling stations (up to 20) were distributed around the Lagoon and particularly concentrated in the area close to the town of Chioggia. Significantly higher (analysis of variance (ANOVA), p<0.05) tributyltin (TBT) concentrations were found in mussels (from 38 ±8 to 6,666 ±1,333 μg kg−1 d.w., as TBT+), than in clams (from 6 ±1 to 2,256 ±451 μg kg−1 d.w., as TBT+). During the 3 years of the survey no increase in average concentrations of the butyltin compounds (tributyltin (TBT) + dibutyltin (DBT) + monobutyltin (MBT)) was observed (ANOVA, p>0.05) in either species. Furthermore, by analyzing the entire data set, it is evident that most stations show analogous concentrations in the 3 years for both species, whereas few have anomalously higher concentrations. If organotin concentrations in specimens from some sites are compared with the Tolerable Average Residue Level, a possible risk for human health must be considered.

Hydro : simulation of hydrodynamics and water pollution

Abstract A user-friendly package for simulations of wind-induced currents and dispersion of non-conservative pollutants in aquatic media is discussed. The hydrodynamics are modelled by a stationary shallow-water approximation of the Eckman type. The generated patterns of currents are fed into the 2-D advection-diffusion model to calculate the concentration fields of a pollutant coming with inflows or injected directly into the water body. The package runs on IBM compatible PCs with a mathcoprocessor being very desirable. The package is simple to learn. It may be useful for preliminary qualitative analysis of water pollution, as well as for education and demonstration purposes.