Ninety percent of the Global Movement of Goods transit by ship. The transportation of HNS (Hazardous and Noxious
Substances) in bulk highly increases with the tanker traffic. The huge volume capacities induce a major risk of accident
involving chemicals. Among the latest accidents, many have led to vessels sinking (Ievoli Sun, 2000 - ECE, 2006).
In case of floating substances, liquid release in depth entails an ascending two phase flow. The visualization of that flow
is complex. Indeed, liquid chemicals have mostly a refractive index close to water, causing difficulties for the assessment
of the two phase medium behavior. Several physics aspects are points of interest: droplets characterization (shape
evolution and velocity), dissolution kinetics and hydrodynamic vortices.
Previous works, presented in the 2010 Speckle conference in Brazil, employed Dynamic Speckle Interferometry to study
Methyl Ethyl Ketone (MEK) dissolution in a 15 cm high and 1 cm thick water column. This paper deals with
experiments achieved with the Cedre Experimental Column (CEC - 5 m high and 0.8 m in diameter). As the water
thickness has been increased, Dynamic Speckle Interferometry results are improved by shadowscopic measurements. A
laser diode is used to generate parallel light while high speed imaging records the products rising. Two measurements
systems are placed at the bottom and the top of the CEC. The chemical class of pollutant like floaters, dissolvers (plume,
trails or droplets) has been then identified. Physics of the two phase flow is presented and shows up the dependence on
chemicals properties such as interfacial tension, viscosity and density. Furthermore, parallel light propagation through
this disturbed medium has revealed trailing edges vortices for some substances (e.g. butanol) presenting low refractive