Experimental harvesting of wetland plants to evaluate trade-offs between reducing methane emissions and removing nutrients accumulated to the biomass in constructed wetlands.

Constructed wetlands built for water treatment often need biomass harvesting to remove nutrients from the system. Usually harvesting is done during the peak growing season to maximize the amount of nutrients removed from the system. This, however, can create huge methane fluxes that escape from plant tissues to the atmosphere. We used manual chambers and eddy covariance measurements to analyze the increase in methane emissions due to the harvesting of two common wetland species, Typha spp. and Schoenoplectus spp., in two climatically different constructed wetlands in Estonia and California. In addition, we determined the biomass nutrient and carbon concentrations from harvested biomass. We found that harvesting during the summer season, e.g. June and August, resulted in a significant release of methane at both sites. At the California site, baseline median methane emissions were 217.6 nmol m-2 s-1, and harvesting resulted in increases to 395.4 nmol m-2 s-1 that decreased to baseline emission within three days. Footprint modeling demonstrated that the emission increases measured by eddy covariance were dominated by contributions from the cut area to the total footprint signal. At the Estonian site, harvesting resulted in methane increases of 15.9 nmol m-2 s-1 to 110.4 nmol m-2 s-1 in August. However, in September and October the emission was significantly lower. Plant biomass analyses showed clear temporal dynamics in terms of nutrient concentration, being highest in summer and lowest in winter. Our experiments indicate that the optimal time for aboveground biomass harvesting is at the end of the growing season before nutrient translocation to belowground plant structures begins coinciding with lowest methane emissions. Therefore, strategic planning of the harvest timing may help reduce greenhouse gas emissions from managed wetlands and thus improve their multi-faceted ecological benefit.

Atypical adenolymphoma and glomus caroticum tumour: a rare coincidence.

We describe the rare simultaneous appearance of an atypical adenolymphoma with a glomus caroticum tumour on the same side of the neck in a middle-aged man. This case report is the first to describe this coexistence. Due to the atypical, cyst-like presentation of the Warthin's tumour, a final diagnosis was made only after surgical resection and histopathological examination. Both the adenolymphoma and glomus caroticum tumour were successfully removed surgically.

Diagnostic procedures in head and neck cancer.

Accurate, methodical diagnostic work up and staging are of the most importance in the treatment of Head and Neck tumours. It allows an initial multidisciplinary decision making, giving the patient the best chance of curation, with the least morbidity. In this paper the authors try to give a generally accepted work-up and try to get in to some of the newer techniques.

[Otologic manifestations of Wegener's disease]. / Otologische manifestaties van de ziekte van Wegener.

Two cases of otologic involvement in Wegener's granulomatosis are reported. Symptoms are referable to those of an acute otitis media with impaired hearing. The ANCA test is helpful in the diagnosis. Immunosuppressive therapy in association with corticosteroids is the treatment of choice.

Evidence for the presence of mutagenic compounds other than chromium in particles from mild steel welding.

A modified Salmonella/microsome liquid culture assay was used to investigate the mutagenicity of the particulate fraction from mild steel welding. Previous reports have implicated compounds of chromium VI as the mutagenic and toxic agents in welding fumes, since only the particles from welding on stainless steel, which contains 15-25% chromium, were mutagenic, whereas particles from welding on mild steel, which contain less than 0.1% chromium, were not mutagenic or toxic. In this investigation, mild steel particles were shown to contain direct-acting and promutagenic compounds that induced frameshift mutations. The mutagenic agents, which were insoluble in sodium phosphate buffer, did not include chromium VI or organic compounds. Further, the expression of mutation appears to require a cell-particle interaction for the release of the mutagenic species from the particles.