Two hundred fifteen cyanobacteria bloom samples collected from different parts of Finland were studied, 35 of which proved to be neurotoxic. Toxicity was determined by mouse bioassay. Anabaena species were present in all neurotoxic samples except one, in which Oscillatoria dominated. The presence of anatoxin‐a in the blooms and in the isolated strains was studied from freeze‐dried materials by gas chromatography/mass spectrometry. The simultaneous occurrence of neurotoxicity and hepatotoxicity in some samples was studied by high performance liquid chromatography and high performance thin layer chromatography. Thirteen out of 30 bloom samples contained anatoxin‐a. In the remaining samples, neurotoxicity was caused by unknown toxin(s). Strains producing anatoxin‐a were isolated from the genera Anabaena, Aphanizomenon, Oscillatoria, and Cylindrospermum. Anatoxin‐a content of the blooms varied from 12 to 4360 μg/g freeze‐dried material. Some strains were able to produce about three times as much anatoxin‐a as was detected in natural blooms. Simultaneous occurrence of neurotoxicity and hepatotoxicity was found in some samples as well as atypical toxic responses in mouse bioassay.
The effectiveness of various drinking water treatment processes has been tested in laboratory and pilot scale experiments using neurotoxic and hepatotoxic cyanobacterial blooms and laboratory‐grown algal cultures as test material. The species involved belonged to the genera Microcystis, Oscillatoria, and Anabaena. Microcystis and Oscillatoria hepatotoxins were analyzed by high performance liquid chromatography. The Anabaena neurotoxin, anatoxin‐a, was determined using gas chromatography/mass spectrometry techniques. Toxicity was tested and verified by mouse bioassay. The laboratory study, made with freeze‐dried cyanobacteria, showed that toxins were not removed by conventional flocculation treatment procedures. The simultaneous addition of a small amount of powdered activated carbon with the flocculation chemical did not improve the removal of hepatotoxins significantly. Substantial reduction of toxins was achieved by granulated activated carbon filtration and by ozonization. Pilot plant studies supported the laboratory findings. Results of the slow sand filtration experiments suggested some removal of toxins.
High-volume samples of ambient air were collected by glass-fiber filter (particulate) and XAD-2 resin (vapor) from three locations in Finland: two cities and a rural area. Samples were analyzed for polynuclear aromatic hydrocarbons (PAH) and selected other polynuclear compounds. Genotoxicity of the samples was assayed in the Ames Salmonellalmicrosome test and sister chromatid exchange assay before and after fractionation into four fractions of increasing polarity. The ratio of PAH in the vapor and particulate phases of the samples varied considerably with the season, and the scavenging effect of snow and rain was as well clearly demonstrated. The rural samples showed minimal or no genotoxic activity, whereas at the urban sites not only the particulate-phase but also the vapor-phase samples were mutagenic. The genotoxicity was mainly associated with the most polar fractions of both phases. Studies with the nitroreductase-deficient Salmonella strain TA98NR indicated that, in the urban air samples collected in winter, a considerable part of the mutagenicity detected in the Ames test was due to NO2-substituted compounds. Traffic is suggested to be the major determinant for the genotoxic activity in the ambient air.
Scanning electron microscopy combined with energy dispersive X-ray analysis (SEM/EDX) was used to identify the gunshot residue (GSR) particles discharged by lead-free Sintox ammunition. Sintox GSR particles are characterized by spheroidal particles mainly consisting of titanium (Ti) and zinc (Zn). The results obtained in this study are in agreement with the hypothesis that GSR particles are formed by rapid condensation and solidification of vaporized and molten primer and bullet materials as a result of sudden temperature quench. The surface morphology of Ti-Zn particles is an essential criterion for their identification as gunshot residue particles and for discrimination against Ti-Zn environmental particles.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.