A HPLC‐based protocol has been developed for the determination of zero‐valent sulfur (ZVS) speciation, including solid, colloidal elemental sulfur and individual inorganic polysulfides in natural aquatic samples. The protocol includes four experimental procedures: (1) determination of polysulfide speciation by rapid single‐phase derivatisation with methyl trifluoromethanesulfonate; (2) determination of the sum of polysulfide and colloidal sulfur by reaction with hydrogen cyanide (cyanolysis); (3) determination of total zero‐valent sulfur by treatment with zinc chloride followed by extraction with chloroform; and (4) chromatographic determination of polythionates without sample pre‐treatment. With proper sampling and preservation techniques in the field or on board ship, this combination of methods allowed the quantitative determination of: (a) individual polysulfide species; (b) dispersed colloidal sulfur; (c) dispersed solid elemental sulfur; and (d) tetra‐, penta‐ and hexathionates. With minor modification, the method could be expanded to include other polythionates. Sixteen various wet chemical and liquid chromatographic methods were tested on nine synthetic reference samples (including solid elemental sulfur, colloidal elemental sulfur, inorganic polysulfides and polythionates) to establish the optimal protocol. The protocol was further evaluated by analysing the zero‐valent sulfur content in microbially‐produced sulfur and in sulfur from two natural samples of sulfide‐rich seawater from tidal flats pools of the Wadden Sea (Germany).

The present study reviews the options of cultivating the green alga, Chlorella emersonii, under photoautotrophic conditions with flue gas derived from a cement plant. It was conducted in the Lafarge Perlmooser plant in Retznei, Austria, where stone coal and various surrogate fuels such as used tyres, plastics and meat-and-bone meal are incinerated for heating limestone. During 30 days of cultivation, flue gas had no visible adverse effects compared to the controls grown with pure CO 2 . The semi-continuous cultivation with media recycling was performed in 5.5-L pH-stat photobioreactors. The essay using CO 2 from flue gas yielded a total of 2.00 g L −1 microalgal dry mass and a CO 2 fixation of 3.25 g L −1 . In the control, a total of 2.06 g L −1 dry mass was produced and 3.38 g L −1 CO 2 was fixed. Mean growth rates were between 0.10 day −1 (control) and 0.13 day −1 (flue gas). No accumulation of flue gas residues was detected in the culture medium. At the end of the experiment, however, the concentration of lead was three times higher in algal biomass compared to the control, indicating that cultures aerated with this type of flue gas should not be used as food supplements or animal feed.

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