A representative sampling of tuna muscle for mercury control

The mechanisms of mercury accumulation and distribution in fish tissues are related to its high affinity for sulfhydryl groups in proteins. There is evidence that mercury is distributed unevenly based on the different reactivity of these groups in the various muscle proteins. Tuna fish also shows numerous specialized anatomical features including the structure of the swimming muscles and some form of endothermy, which generates variations in the mercury content between dark and white muscle and between muscle tissues with different lipid content. The aim of the study is to verify, through a suitable sub lot of Thunnus thynnus caught by a static trap in south-western Sardinia, the effective uneven distribution of mercury in the various muscles and also identify the sites representative of the entire carcass. In agreement with other authors, the results show that even in the Bluefin tuna of the Mediterranean, the site “anterior extremity of upper loin (schienale in Italian)” is representative of the mercury average content of muscle tissues as a whole.

Study of Foam Flow in a Gas-Liquid Cylindrical Cyclone (GLCC) Compact Separator

Aqueous foam flow behavior in a Gas-Liquid Cylindrical Cyclone (GLCC) is studied experimentally and theoretically with the objective of determine the operational envelop for foam break up. An existing experimental two-phase facility was modified to enable foam flow characterization. Several experimental data were acquired for aqueous foam using a compact inlet cyclone. These include: foam characterization in static trap sections, and foam flow behavior in the cyclone. Saint-Jalmes et al. (2000) model has been modified for characterization of foam evolution in static trap sections including the prediction of the drainage interface height with time. In addition, a new model for the prediction of the operational envelop for foam break up in the cyclone based on foam characteristics was developed. Good agreement is observed between the experimental data and the predictions of the models. It can be concluded that depending on the operational conditions the GLCC can act either as a foam breaker or as a foam generator. The developed model for the prediction of the operational envelop for foam break up separates these two modes of operations of the GLCC.