Global comparison of VOC and CO observations in urban areas

Speciated volatile organic compound (VOC) and carbon monoxide (CO) measurements from the Marylebone Road site in central London from 1998 through 2008 are presented. Long-term trends show statistically significant decreases for all the VOCs considered, ranging from ?3% to ?26% per year. Carbon monoxide decreased by ?12% per year over the measurement period. The VOC trends observed at the kerbside site in London showed greater rates of decline relative to trends from monitoring sites in rural England (Harwell) and a remote high-altitude site (Hohenpeissenberg), which showed decreases for individual VOCs from ?2% to ?13% per year. Over the same 1998 through 2008 period VOC to CO ratios for London remained steady, an indication that emissions reduction measures affected the measured compounds equally. Relative trends comparing VOC to CO ratios between Marylebone Road and Hohenpeissenberg showed greater similarities than absolute trends, indicating that emissions reductions measures in urban areas are reflected by regional background locations. A comparison of VOC mixing ratios and VOC to CO ratios was undertaken for London and other global cities. Carbon monoxide and VOCs (alkanes greater than C₅, alkenes, and aromatics) were found to be strongly correlated (>0.8) in the Annex I countries, whereas only ethene and ethyne were strongly correlated with CO in the non-Annex I countries. The correlation results indicate significant emissions from traffic-related sources in Annex I countries, and a much larger influence of other sources, such as industry and LPG-related sources in non-Annex I countries. Yearly benzene to ethyne ratios for London from 2000 to 2008 ranged from 0.17 to 0.29 and compared well with previous results from US cities and three global megacities.     

Removal of hexafluoroarsenate from waters

Arsenic predominantly occurs in natural ground and surface waters as arsenate and arsenite. Other arsenic species can also be present in anthropogenically influenced waters. By means of a newly-developed speciation technique an arsenic compound was identified as hexafluoroarsenate at high concentration (about 0.8mgl(-1) as As) in a lake polluted by waste water from a former crystal glass factory. This compound shows a completely different behavior than common arsenite and arsenate in waters. However, respective literature data were little found regarding its environmental behavior as well as the applicable remediation technologies. Conventional arsenic treatment mechanisms, such as the well-known sorption to iron hydroxides, can not be used to remediate water with this compound. Hence, an effective method to remove hexafluoroarsenate from water was developed using its strong affinity to anion exchangers (strong basic exchangers with quaternary ammonium groups). The sorption can be described by a Langmuir isotherm and first-order kinetics with a half-life of about 10min. Interferences by sulphate and fluoride, present at much higher concentrations in the polluted lake water, might be expected due to the anion exchange mechanism, but were shown to be of minor importance.     

Optimisation of reduction of global CO2 emission based on a simple model of the carbon cycle

A simple model has been designed to describe the interaction of climate and biosphere. Carbon dioxide, understood as a major emitted gas, leads to a change of global climate. Economic interpretation of the model is based on the maximisation of the global CO₂ cumulative emissions. The two most important profiles of emission have been obtained: optimal and multi-exponential suboptimal profiles, each displaying different characteristics. This revised version was published online in July 2006 with corrections to the Cover Date.     

Drugs from marine organisms

A modern approach to the search for biologically active substances of potential therapeutic use isolated from marine organisms is illustrated by a presentation of the multidisciplinary project pursued by the Roche Research Institute of Marine Pharmacology near Sydney, Australia. This specialized insitute is part of the world-wide research endeavour of our company and has now been in operation for five years. Following a brief outline of the technical functions the main scientific achievements published by the scientists of the institute are reviewed. This institute is, to our knowledge, the only one of its kind in private industry and we have attempted to demonstrate how its activities should be viewed in the overall context of today's drug or product development.     

Estimation of mercury content in tailings of the gold mine area of Poconé, Mato Grosso,Brazil

As in many other parts of the world, gold is produced in the surface mining region of Poconé, Mato Grosso, Brazil, using mercury. The goal of this investigation was to estimate the amount of mercury in certain tailings and to determine the area of the land that has been contaminated by the gold mining operations. Mercury concentrations from 2 to 495 ng/g (dw) were determined in the tailing materials. It was observed that only isolated sites were acting as central points of contamination. Using digital Landsat satellite data (The-matic Mapper) and aerial photos, the sites degraded by the mining were classified, and their total area was estimated to be 12.3 km² in the region of Poconé. It was estimated, that 4.9 km² were occupied by the contaminated tailings. The mean height of the pile slags was determined to be 4.5 m. From the experimentally calculated average density of the material in the tailings, 2.01 g/cm³, the total mercury content in the piles of tailings was estimated to be 1600 ± 350 kg.     

Phosphorus recovery from wastewater--expert survey on present use and future potential

Today, a variety of different approaches to the recovery of phosphorus from wastewater, sludge, and sludge ash exist. These approaches differ basically by the origin of the used matter (wastewater, sludge liquor, fermented or nonfermented sludge ash) and the process (precipitation, wet-chemical extraction, and thermal treatment). To rate them according to their characteristics, the latter were phrased as hypotheses and subjected to an international expert survey. The survey showed that phosphorus recovery is expected to become an established process over the next 20 years in industrialized countries for economic reasons. A decisive aspect in this regard will be the quality of the produced fertilizer. Simple technologies such as the recovery from sludge liquor seem to be preferred. If sludge is incinerated, phosphorus recycling from ash then becomes more interesting and has to be considered. Phosphorus recovery and source-separating sanitation technologies are more appropriate for industrialized countries than for developing countries. Because the growing awareness of environmental issues will prevent sludge from being used agriculturally in an increasing number of countries in the next decade, the market potential for nutrient recovery technologies will increase in the immediate future.     

Trihalomethane formation during water disinfection in four water supplies in the Somes river basin in Romania

Background, aim and scope  

After the discovery of chloroform in drinking water, an extensive amount of work has been dedicated to the factors influencing the formation of halogenated disinfections by-products (DBPs). The disinfection practice can vary significantly from one country to another. Whereas no disinfectant is added to many water supplies in Switzerland or no disinfectant residual is maintained in the distribution system, high disinfectant doses are applied together with high residual concentrations in the distribution system in other countries such as the USA or some southern European countries and Romania. In the present study, several treatment plants in the Somes river basin in Romania were investigated with regard to chlorine practice and DBP formation (trihalomethanes (THMs)). Laboratory kinetic studies were also performed to investigate whether there is a relationship between raw water dissolved organic matter, residual chlorine, water temperature and THM formation.     

Improving soil investigations at brownfield sites using a flexible work strategy and screening methods inspired by the US Environmental Protection Agency's triad approach

Investigations of polluted brownfield sites and sample analyses are expensive, and the resulting data are often of poor quality. Efforts are needed, therefore, to improve the methods used in investigations of brownfield sites to both reduce costs and improve the quality of the results. One approach that could be useful for both of these purposes is the triad strategy, developed by the US Environmental Protection Agency, in which managing uncertainty is a central feature. In the investigations reported here, a field study was conducted to identify possible ways in which uncertainties could be managed in practice. One example considered involves optimizing the uncertainty by adjusting the sizes of samples and the efforts expended in analytical work according to the specific aims of the project. In addition, the potential utility of several toxicity assessment methods for screening sites was evaluated. As well as presenting the results of these assessments, in this contribution we discuss ways in which a flexible work strategy and screening methods inspired of the triad philosophy could be incorporated into the Swedish approach to remediate brownfield sites. A tiered approach taking advantage of field and screening methods is proposed to assess brownfield sites focusing on the response and acceptable uncertainty that are required for the task.     

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