Assessment of heavy metals in sediment and in suspended particles affected by multiple anthropogenic contributions in harbours

La Goulette, Rades and Sidi Bou Said harbours are considered as the most important commercial and tourist ports in the Gulf of Tunis. They are located on the northeast coast of Tunis and receive industrial and municipal wastewaters from Tunis city. The contamination level of copper, lead, zinc, cadmium, manganese, iron, total nitrogen and total organic carbon in the surface sediments was assessed on the basis of the enrichment index factors and corresponding to sediment quality guidelines. The results revealed moderate to highly elevated concentrations near to the sites of intense industrial, shipping and/or commercial activities suggesting a direct influence of these sources. In winter and summer, concentrations varied for cadmium, 0.28–1.40 mg kg-1; lead, 18–217 mg kg-1; zinc, 87–459 mg kg-1; copper, 8–121 mg kg-1; manganese, 208–254 mg kg-1; and for iron, 24–40 g kg-1. Furthermore, in summer the concentration of the total organic carbon and the total nitrogen contents range between 4.3–6.5 % and 0.06–0.49 % with an average value of 5.9 and 0.15 %, respectively. Whereas, in winter, total organic carbon and the total nitrogen concentrations varied between 2.3–9.6 % and 0.03–0.22 % with an average value of 6.1 and 0.14 %, respectively. The levels of lead, copper, zinc and iron in suspended particulate matter content range between 3.1–27.5 mg kg-1; 0.4–11.7 mg kg-1; 1–1.5 mg kg-1; 1.2–1.7 g kg-1, respectively. This study revealed that heavy metals pollution is mainly localized in the commercial (Rades) and fishing (La Goulette) harbours and not in the yachting (Sidi Bou Said) harbour

Calibrage automatique d’un convertisseur Sigma-Delta utilisant un BIST

National audienceCet article présente l’utilisation d’une technique de test intégré (BIST pour Built In Self Test) qui permet la mesure du signal sur bruit avec distorsion (SINAD) d’un convertisseur sigma-delta (SD) comme outil de calibrage de ce circuit. La mise en valeur de cette méthode fut effectuée en utilisant un circuit intégré comprenant un modulateur SD du second ordre et le BIST, un circuit programmable (FPGA) et des potentiomètres numériques. Ces derniers permettent de modifier les tensions de polarisation de l’amplificateur opérationnel constituant le modulateur. Le démonstrateur conçu est aussi piloté par une interface graphique sous Labview ®

A Stereo Audio ΣΔ ADC Architecture with Embedded SNDR Self-Test

International audienceIn this paper we present a new architecture for audio Analog-to-Digital Converters (ADCs) that includes a Built-In Self-Test (BIST) technique for the test of the Signal-to-Noise and Distortion Ratio (SNDR). A periodical binary stream is generated in the chip in order to stimulate the converter. The reuse of the bandgap circuit already existing in the converter allows us to generate the test stimulus with a very small analog area overhead. The output response analysis is performed by means of a sinewave fitting algorithm. The reuse of the digital filter already existing in the converter allows us to generate a synchronized reference signal necessary for the fitting algorithm. The BIST technique is equivalent to a standard test carried out with a sinusoidal signal at -12 decibels Full-Scale (dBFS). The total test time is 60 ms and the estimated BIST overhead area is 7.5% of the whole stereo converter area in a 0.13 μm CMOS technology. Experimental results show that the correlation between the embedded self-test and a sinusoidal standard test is excellent, with a SNDR error smaller than 1 dB

Contaminated sediment resuspension induces shifts in phytoplankton structure and function in a eutrophic Mediterranean lagoon

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Impact of climate change and river managements on the reduction of sediment transport to the sea in Maghreb

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Styela plicata: a new promising bioindicator of heavy metal pollution for eastern Aegean Sea coastal waters

As part of a research project, the concentrations of Cd, Cu, Pb, V, and Zn in the tissues of Styela plicata were investigated for the first time to determine if S. plicata is a suitable biological indicator for biomonitoring of heavy metals in eastern Aegean Sea coastal waters. To examine the relationships, heavy metal levels in suspended particulate matters (SPMs) and sediments were also determined. According to the results, the mean metal levels in SPM, sediments, and S. plicata samples could be arranged in the following order of abundance: Zn > Cu > Pb > V > Cd. As for heavy metal levels, significant positive correlations were noted between Cd-Pb, Cd-V, Cd-Zn, Cu-V, and Pb-V in SPM; Cd-Zn, Cu-Zn, Pb-Cd, Pb-Cu, and Pb-Zn in sediment; and Cu-Pb, Cu-Zn, and Pb-Zn in S. plicata samples. Positive relationships between these metals showed that they were originated from same sources and that they were associated with each other. Based on the findings, Zn, Cu, and Pb concentrations in suspended particulate matters, sediments, and S. plicata samples were generally represented with higher levels at stations that were used for boating, shipping, and related activities. As S. plicata is a strongest accumulator of V, the relatively low V levels observed in this study may indicate the lack of anthropogenic sources of this metal in the sampling stations. In conclusion, suspended particulate matter and sediment can be useful tool to detect the pollution status of the marine environment. Furthermore, the findings of this study highlighted that S. plicata is a promising alternative for the monitoring of heavy metal pollution for eastern Aegean Sea coasts