The rheological and viscoelastic properties of mayonnaise emulsions with different size of oil droplets were investigated. Α programmable rotational rheometer was used for the measurements and flow curves were determined at constant and variable shear rate. Mayonnaise exhibited a non-Newtonian, shear-thinning flow with yield stress and time-dependent features. The data from rotational tests were modeled by the Herschel-Bulkley equation. The temperature-dependence of η a was modelled using the Arrhenius equation. Activation energy, E a ranged from 15 to 20 kJ/mol. Viscoelastic properties were characterized using small amplitude oscillatory shear. Mayonnaise exhibited weak gel-like properties. The values of apparent and complex viscosity were correlated using the generalised Cox-Merz rule. According to the obtained values of parameter α, this rule could not be cut-down to one-parameter linear function. The rheological characteristics of mayonnaise were well correlated to the size of oil droplets.

Heavy metal content of high load ashes applied on the ground during severe forest fires may be released into rainwater, and through it, they can either penetrate into the ground water or be washed out into water receivers, causing a severe environmental problem. The chemical composition of two dominant Greek forest species (Pinus halepensis, Quercus coccifera) ashes was determined before and after leaching. The ash samples were similar to those obtained in actual forest fires and two leaching tests (column and shake leaching test) were employed using aqueous solutions of pH=6 and 1. For the analysis of ashes (prior to and after leaching), the following analytical techniques were used: X-ray diffraction and scanning electron microscopy with energy dispersive X-ray analysis. For the analysis of leachates ion chromatography and inductively coupled plasma emission spectrometry were used. At pH=6 (rainwater conditions) some elements were released (i.e., 95% Cr, 70% Pb). The release of Cr is up to 95% for P. halepensis and 76% for Q. coccifera. The total amount of some toxic elements recovered (i.e., Cd) was up to 99%. As expected, at pH=1 the majority of metallic elements were almost completely recovered. Knowledge of the leaching properties of Mediterranean forest species ashes is very important for evaluating their impact on the environment (soil and ground and underground water streams).

A serial batch leaching experiment has been carried out to evaluate the release of elements from the ash of Pinus halepensis needles burned under two test conditions-with and without treatment of the forest species with the carbonate minerals (huntite and hydromagnesite) in aqueous solution (pH 6). The ash (before and after leaching) and leachates were analyzed using atomic absorption spectroscopy and X-ray diffraction. Compared with data from samples treated with the commercially available, phosphate-based fire retardant diammonium phosphate (DAP), we found that use of huntite or hydromagnesite was much more successful in obstructing the release of the toxic elements present in the ash, probably because of the alkaline conditions resulting from decomposition of the minerals during burning. In contrast, DAP tended to be more able to facilitate the extraction of some toxic metals (e.g., Zn, Cu, Mn), probably because of the acidic conditions resulting from its decomposition to phosphoric acid. Data from this study thus lend strong support to the use of magnesium carbonate minerals as new wildfire retardants, because they were shown to be more friendly to the environment (e.g., soil, ground, and underground water streams) than those currently in use (e.g., phosphate or sulfate salt type).

The chemical, mineralogical, and leaching behavior of three dominant Greek forest species ashes (Pinus halepensis, Pistacia lentiscus, and Olea europaea), before and after treating forest species with diammonium phosphate (DAP) 5% and 10% weight to weight, have been studied using a new five-step shake leaching method at pH=6. For the analysis of ashes (prior and after leaching) and leachants, the following analytical techniques were used: atomic absorption spectroscopy, X-ray diffraction, and scanning electron microscopy with energy dispersive X-ray fluorescence analysis. The presence of DAP obstructs the extraction process of some metal ions (i.e., Na, K) contained in ashes by converting the soluble carbonate salts to the less soluble phosphates (i.e., Na 2 CO 3 → Na 3 PO 4 ). On the contrary, DAP enhances the mobility of some other metals (i.e., Ca) by forming more soluble compounds [i.e., CaCO 3 → Ca 3 (PO 4 ) 2 ]. In addition, the presence of DAP lowers the pH of leachates, causing dissolution of some toxic elements (i.e., Mn, Pb, Zn). Unexpectedly, DAP prevents the leachability of Cr from ash. The above study concerns the environmental effects (soil and ground and underground water streams) caused by the use of chemical retardants on forest fires.