Molecular phylogeny and population structure of tideland snails in the genus Cerithidea around Japan

Phylogenetic relationships and genetic population structures were analyzed for tideland gastropods in the genus Cerithidea around Japan on the basis of partial sequence of the mitochondrial COI gene. Large genetic divergence was shown between individuals of Cerithidea cingulata in the southern Ryukyus and those in the central Ryukyus and the Japanese Islands. Haplotypes of C. cingulata from the Japanese Islands were paraphyletic with the exclusion of a monophyletic group from the central Ryukyus. Genetic differentiation of C. cingulata was also detected between Amami-Oshima Island and Okinawajima Island. No genetic divergence was found between Cerithidea rhizophorarum in the Japanese Islands and its subspecies C. rhizophorarum morchii in the Ryukyu Islands. The lack of genetic divergence of Cerithidea largillierti between continental China and Japan suggests relatively recent migration between the Japanese Islands and the Asian continent. For all three Cerithidea species distributed in both the Japanese Islands and the Ryukyu Islands, the Tokara Gap and the Kerama Gap were shown to have acted as barriers to the dispersal.     

Analysis of polycyclic aromatic hydrocarbons (PAHs) in airborne particles by direct sample introduction thermal desorption GC/MS

The technique of thermal desorption (TD)–GC/MS was evaluated for measuring airborne, 4–6 ring polycyclic aromatic hydrocarbons (PAHs) collected onto quartz filters. TD provides a more readily automated and sensitive alternative to traditional solvent extraction, decreasing the time/cost of analysis and reducing the risk of analyte loss or sample contamination. The developed method was successfully applied to the analysis of PAH standard solutions loaded on sorbent tubes packed with quartz wool and the graphitized carbon black sorbent Carbograph2. The optimized method showed high desorption efficiency over the whole range of target PAHs with good precision, linearity and sensitivity. The proposed method was verified on an urban dust Standard Reference Material (SRM 1649a); the experimentally determined concentrations agreed with the certified ranges (95% confidence limit) for all target compounds except benzo[a]anthracene, which fell just outside the narrow certified range. The desorption efficiency and the reproducibility of the method was evaluated by analysing pieces of real sample filters sampled from urban air for a period of 24 h. The results confirmed the homogeneity of the filter and showed high recovery efficiencies for all target PAHs.     

Lateral migration and offsite surface emission of landfill gas at City of Montreal Landfill Site

An evaluation of lateral landfill gas migration was carried out at the Saint-Michel Environmental Complex in Montreal, City of Montreal Landfill Site, Canada, between 2003 and 2005. Biogas concentration measurements and gas-pumping tests were conducted in multilevel wells installed in the backfilled overburden beside the landfill site. A migration event recorded in autumn 2004 during the maintenance shutdown of the extraction system was simulated using TOUGH-LGM software. Eleven high-density instantaneous surface monitoring (ISM) surveys of methane were conducted on the test site. Gas fluxes were calculated by geostatistical analyses of ISM data correlated to dynamic flux chamber measurements. Variograms using normal transformed data showed good structure, and kriged estimates were much better than inverse distance weighting, due to highly skewed data. Measurement-based estimates of yearly off-site surface emissions were two orders of magnitude higher than modelled advective lateral methane flux. Nucleodensimeter measurements of the porosity were abnormally high, indicating that the backfill was poorly compacted. Kriged porosity maps correlated well with emission maps and areas with vegetation damage. Pumping tests analysis revealed that vertical permeability was higher than radial permeability. All results suggest that most of the lateral migration and consequent emissions to the atmosphere were due to the existence of preferential flow paths through macropores. In December 2006, two passively vented trenches were constructed on the test site. They were successful in countering lateral migration.     

RESEARCH: Shrub Propagation Techniques for Biological Control of Invading Tree Species

Cornus stolonifera, Salix petiolaris, and Spiraea alba clones already located within the corridor of an electrical power line. To establish the efficiency of treatments, we examined the statistical differences of growth traits between species and treatments. An analysis of the effects of layering shows, after the first growth season, differences for all growth traits in only one species, Spiraea alba. After the second growth season, we observed the development of new aerial stems. Layering favors horizontal expansion of shrubs over height development. The third year after treatment, the effect of layering is reduced except for Cornus stolonifera, which continuously increases, as shown by the significant progression of the clone issued from the layer even five years after treatments. With the cutting back technique, we expected a distinct vertical growth of the shrubs at the expense of increasing the crown diameter. This technique would be best associated with the rejuvenation of clones, followed by a layering of new shoots to allow a horizontal expansion of the shrubs. Therefore, the formation of a dense shrub community by layering should be considered a valuable approach for the biological control of undesirable trees in powerline rights-of-way.