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This study evaluated the distribution of polychlorinated biphenyls (PCBs) in 39 surface sediment samples and four cores collected in Toulon Bay, a semiclosed area submitted to various anthropogenic inputs. The concentration of PCBs in the superficial sediment samples ranged from 1.7 to 2530 ng g−1 dry weight. The spatial distribution of these compounds suggested that the high concentrations of these contaminants are located in the small bay and are related to human activities. In the larger bay, the concentrations were in the same order of magnitude than those reported in others locations around the world. Comparison of the levels with target values from the French legislation shows that, except for four polluted sites with critical values (N2: values ≥1 mg kg−1 dry weight) in the smaller bay, PCBs levels throughout the larger and the smaller bay are lower than the accepted values (N1: values <0.5 mg kg−1 dry weight). The PCBs in the sediment cores ranged from 0.8 to 739 ng g−1 dry weight dependent core. Vertical profiles indicated earlier usage of PCBs which coincided with the history of the Toulon Bay. In this study, using alkane, we could follow the PCBs pollution history over about 80 years and estimate a sedimentation rate of about 0.32 cm year in the small Bay of Toulon.Electronic supplementary materialThe online version of this article (doi:10.1186/s40064-016-2715-2) contains supplementary material, which is available to authorized users.

A two-dimensional (2-D), time-stepped finite-element (FE) method is used to model and successfully replicate saturated line-to-line and three-phase short-circuit test responses recorded on a 40-pole 13.75-MVA hydrogenerator at Hydro-Quebec's Rapides-des-Quinze generating station. Three levels of line-to-line and sudden three-phase short-circuit tests (0.13, 0.25, and 0.48 p.u.) are simulated numerically using the FE-based model. While symmetrical faults are only used for parameter determination, the computed line-to-line waveforms are thoroughly compared to real data, with special attention given to field current responses. According to IEEE Std.-115-1995, the -axis dynamic reactances and time-constants are computed from three-phase short-circuit tests while the negative-sequence reactance is derived from the line-to-line short-circuit test resulting in a rated armature current. The obtained simulated tests responses and parameter values, from both symmetrical and asymmetrical faults, support the effectiveness of the proposed FE-based model in incorporating the saturation phenomenon, large number of poles, and detailed damper representation to achieve an accurate dynamic performance assessment together with negative-sequence reactance and dynamic constants prediction. Index Terms-Performance and parameter predictions, synchronous machines, transient electromagnetic analysis.

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