Algae contain high amounts of arsenic in the form of arsenosugars. The metabolism and toxicology of these arsenic species are not yet fully understood. Three sets of experiments have been conducted in which the alga Laminaria was ingested by 2 to 5 healthy volunteers. Total arsenic concentrations in urine and in blood, packed blood cells and serum have been determined using ICP-MS and HGAFS, respectively. Neutron activation analysis was used for the determination of the total arsenic content in algae samples. Speciation analysis of urine and serum samples has been carried out using HPLC-ICP-MS. HPLC-ES-MS/MS has been used for structural confirmation. The stability of the arsenosugars in simulated gastric fluid was studied for both boiled and unboiled seaweed. A maximum level of arsenic in urine appears within 15 to 25 h after ingestion. Total arsenic and speciation analysis revealed no marked increase in arsenic blood, serum and packed cells levels up to 7 h after ingestion. Dimethylarsinic acid (DMA), methylarsonic acid (MA) and dimethylarsinoylethanol (DMAE) have been positively identified in urine sampled after algae intake. Another 5 species remain unknown. In simulated gastric fluid incubated with algae, the larger share of the arsenosugars degrade within a short time span into a compound with a mass of 254 Da.

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We have monitored the growth of lead decanoate coatings in real time using electrochemical impedance spectroscopy (EIS) and synchrotron X-ray diffraction in a unique environmental cell. The measurements involved the immersion of lead substrates in a 0.05 M sodium decanoate solution and the simultaneous collection of spectroscopic and electrochemical data as the coating deposits. In separate experiments, the surface morphology was investigated with SEM. The stratigraphy and thickness of layers after 6 h of treatment ( ∼ =1.5 µm) was determined using RBS and ultra low energy SIMS combined with surface profilometry. Weight-gain measurements were also carried out. Overall, the results are consistent with an initially parabolic process, due simply to diffusionally limited two-dimensional growth across the surface from nucleation sites. This becomes linear over time as one-dimensional vertical growth sets in at full coverage (layer closure). The X-ray data and the microscopy show that the coating consists of fine, interlocking, randomly oriented flake-shaped crystals, with no obvious epitaxial relationship to the lead substrate. The growth rate of the coating and its corrosion resistance are extremely sensitive to preparation method of the NaC 10 solution in ways which are still under investigation.

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