Peatland Microbial Communities as Indicators of the Extreme Atmospheric Dust Deposition

We investigated a peat profile from the Izery Mountains, located within the so-called Black Triangle, the border area of Poland, Czech Republic, and Germany. This peatland suffered from an extreme atmospheric pollution during the last 50 years, which created an exceptional natural experiment to examine the impact of pollution on peatland microbes. Testate amoebae (TA), Centropyxis aerophila and Phryganella acropodia, were distinguished as a proxy of atmospheric pollution caused by extensive brown coal combustion. We recorded a decline of mixotrophic TA and development of agglutinated taxa as a response for the extreme concentration of Al (30 g kg−1) and Cu (96 mg kg−1) as well as the extreme amount of fly ash particles determined by scanning electron microscopy (SEM) analysis, which were used by TA for shell construction. Titanium (5.9 %), aluminum (4.7 %), and chromium (4.2 %) significantly explained the highest percentage of the variance in TA data. Elements such as Al, Ti, Cr, Ni, and Cu were highly correlated (r>0.7, p<0.01) with pseudostome position/body size ratio and pseudostome position. Changes in the community structure, functional diversity, and mechanisms of shell construction were recognized as the indicators of dust pollution. We strengthen the importance of the TA as the bioindicators of the recent atmospheric pollution

Quantitative x-ray microfluorescence analysis of small areas and individual particles

During the past few years, rapid progress has been made in the development of collimated x-ray sources which permit energy-dispersive x-ray analysis of small areas with dimensions below 100 μm. An x-ray microfluorescence spectrometer developed at NIST employs a commercial low-power (50 WATTS) x-ray tube providing a small focused x-ray beam (0.25 × 0.25 mm). The x-ray beam size was further reduced with a Mo collimator tipped with a Pt foil having a 70μm hole in the center. The x-ray beam profile was measured by step scanning across Cu wires 50 μm in diameter in both X and Y directions. The cross section of the beam was approximated by a Gaussian function with a FWHM of 43 μm. A schematic diagram of the spectrometer which is capable of operation in vacuum is shown in Figure 1.Other features include a close coupled source-sample-detector for optimum count rate, a motorized x-y stage, and a color video camera for continuous viewing of the sample at normal incidence.</jats:p

Research in the Quantitative Analysis of Individual Particles by X-Ray Fluorescence Spectrometry

In a previous publication, we compared measurements of the x-ray microfluorescence of calcium and iron from homogeneous spherical glass particles with the results of Monte Carlo simulation. That work was performed to verify a Monte Carlo model developed for the characterization of particle size effects using a polished flat sample of the same composition as a reference standard. The present work extends our comparison to synthetic glass particles containing elements of higher atomic number. We also modified our Monte Carlo model to include simulation of x-ray fluorescence from elements in irregular shaped synthetic particles. In addition, the Compton scattering from spherical and irregular shaped particles was simulated using Monte Carlo and compared with experimental measurements.</jats:p

Point source inoculation of Mesocyclops (Copepoda : Cyclopidae) gives widespread control of Ochlerotatus and Aedes (Diptera : Culicidae) immatures in service manholes and pits in North Queensland, Australia

This study details the novel application of predacious copepods, genus Mesocyclops, for control of Ochlerotatus tremulus (Theobald) group and Aedes aegypti (L.) mosquito larvae in subterranean habitats in north Queensland, Australia. During June 1997, 50 Mesocyclops sp. I were inoculated into one service manhole in South Townsville. Wet season rainfall and flooding in both 1998 and 2000 was responsible for the dispersal of copepods via the underground pipe system to 29 of 35 manholes over an area of 1.33 km(2). Significant reductions in Aedes and Ochlerotatus larvae ensued. In these habitats, Mesocyclops and Metacyclops were able to survive dry periods, when substrate moisture content ranged from 13.8 to 79.9%. At the semiarid inland towns of Hughenden and Richmond, cracking clay soil prevents drainage of water from shallow service pits where Oc. tremulus immatures numbered from 292-18,460 per pit. Introduction of Mesocyclops copepods into these sites during May 1999 resulted in 100% control of Oc. tremulus for 18 mo. One uninoculated pit subsequently became positive for Mesocyclops with resultant control of mosquito larvae