Simultaneous measurements of formaldehyde and nitrous acid in dews and gas phase in the atmosphere of Santiago,Chile

The amounts of formaldehyde and nitrous acid (HONO) in gas phase and dews of Santiago de Chile were simultaneously measured. Formaldehyde concentrations values in the liquid phase (dews) correlate fairly well with those in the gaseous phase and are even higher than those expected from gas–dew equilibrium. On the other hand, nitrite concentrations in dews were considerably smaller (ca. 15 times) than those expected from the gas-phase concentrations. This under-saturation is attributed to diffusion limitations due to the relatively large HONO solubility. In agreement with this, under-saturation increases with the rate of dew formation and the pH of the collected waters, factors that should increase the rate of gas to liquid HONO transfer required to reach equilibrium.     

Powerful data analysis routine helps locate buried bombs

Heavy bombing during World War II in Europe, particularly in Germany, left thousands of unexploded bombs buried underground and underwater. The bombs can be detected with magnetic sensors, but sorting through the huge amounts of data generated in area searches has proven to be by far the most difficult part of the task. Recently, a data analysis program has been developed that is capable of correlating global positioning system (GPS) data to magnetic sensor readings to identify likely bomb site candidates in a remarkably short period of time. A key to the success of this application is the use of packaged data-analysis software, Origin, from Microcal Software, Inc. (Northampton, Massachusetts), which is capable of interfacing to external C and C++ pattern curve-fitting routines that operate at the required high rates of speed.     

From molecules to materials — a novel route for the synthesis of advanced ceramics

Dedicated to Prof. Dr. E. Fluck The present contribution reports on the synthesis of novel ceramic materials from molecular precursors like inorganic-organic hybrid polymers. This process, denoted as polymer pyrolysis, was developed in the mid-1970s for the fabrication of inorganic fibers made of silicon carbide (SiC). Current investigations and results in this field of research are highlighted. The main topics reviewed are related to the synthesis of appropriate polymeric ceramic precursors, especially for the preparation of multicomponent materials, the processing of the molecular compounds to ceramic components, and finally to the characterization of the material properties.     

Photocatalytic degradation of trinitrotoluene and other nitroaromatic compounds

The photocatalytic degradation of 2,4,6-trinitrotoluene and ten other nitroaromatic compounds in aerated TiO₂ suspensions has been studied. The following order of reactivity was observed: nitrotoluenes > nitrobenzene > dinitrotoluenes . dinitrobenzenes > 2,4,6-trinitrotoluene > 1,3,5-trinitrobenzene, which reflects the known influence of nitro groups towards the attack of electrophilic reagents on the aromatic molecule.     

(M)VOC and composting facilities. Part 1: (M)VOC emissions from municipal biowaste and plant refuse

GOAL, SCOPE AND BACKGROUND: Malodorous volatiles derived from the decomposition of biowaste within the process of composting might pose a risk to human health. Different techniques of process engineering have been developed to minimise the burden of malodorous compounds in air possibly affecting compost workers and residents in the vicinity. METHODS: In the present study, three different composting facilities were examined for the emission of volatiles to estimate the impact of process engineering on the dispersal of odorous compounds and to discuss its relevance for human health. RESULTS AND DISCUSSION: Concentrations of single compounds belonging to alcohols, ketones, furanes, sulfur-containing compounds and especially terpenes ranged from 10(2) up to nearly 10(6) ng/m3 depending on the sampling sites and the process engineering. The ratio of MVOC and total VOC measured changed throughout the process of biodegradation. A certain combination of volatile compounds coincided with the occurrence of typical compost odour. CONCLUSION: The type of process engineering seemed to have a major impact on the emission of volatiles, as amounts of (microbial) volatiles emitted were characteristic for the different techniques used. Thus, the MVOC emission basically depends on the degree of biodegradation. It is likely that the concentrations workers are exposed to can have an impact on human health. RECOMMENDATIONS AND OUTLOOK: It is obvious that less sophisticated types of process engineering give rise to greater amounts of bioaerosols and volatiles and, therefore, technical devices have to be improved and controlled regularly to minimise adverse health effects on workers.     

Analysis of particle-associated semi-volatile aromatic and aliphatic hydrocarbons in urban particulate matter on a daily basis

PM_2.5 Particle-associated semi-volatile organic compounds (SVOC) were determined in the city of Augsburg, Germany. Daily samples were collected at a central monitoring station from late summer to late autumn 2002. The concentrations of polycyclic aromatic hydrocarbons (PAH), oxidized PAH (O-PAH), n-alkanes, hopanes and long chain linear alkylbenzenes were determined by direct thermal desorption-gas chromatography-time of flight mass spectrometry (DTD-GC-TOFMS). Additionally, PM_2.5 particle mass and number concentrations were measured. The sampling campaign can be divided into two parts, distinguished by a lower temperature level in the second part of the campaign. The particulate mass concentration showed no significant changes, whereas most of the SVOC had significant higher mean and peak concentrations in the colder period. The analysis of the data showed an increased influence of non-traffic sources in the colder period, reflected by a weak shift in the PAH profile and a significant shift in the hopane pattern. Statistical analysis of the inter-group correlations was carried out. Eight clusters partly representing different sources of the aerosol have been identified.