Medical radioisotopes in the environment – following the pathway from patient to river sediment

Motivated by the detection of ¹³¹I in river sediment in routine long-term surveillance samples, a systematic short-term study of the wastewater treatment chain was planned and conducted. Inflow, effluent and primary sludge were collected on a daily basis during two weeks at a regional wastewater treatment plant. Samples were investigated by gamma spectroscopy. Four medically used isotopes could be identified (¹³¹I and ^99mTc regularly, ¹⁵³Sm and ¹²³I sporadically). The concentration levels coincide well with literature data for ¹³¹I, and with our own long-term data for ¹³¹I and ^99mTc for the same plant. Cosmogenic ⁷Be activity in primary sludge correlated well with rainfall intensity. Surface sediment was sampled at low tide at both shores of the river, up- and downstream of the plant. ¹³¹I was identified in all samples, with a sharp maximum (about 100 Bq kg⁻¹ d.m.) at the discharge point of the plant and lower levels elsewhere, decreasing monotonically in downstream direction. ⁷Be and ¹³⁷Cs showed the same behaviour, but no peak at the discharge point. Predictions from simple equilibrium models for the transport and sedimentation of ¹³¹I show good agreement with the experimental data and suggest that the wastewater treatment plant is the main source for this isotope.     

Aryl hydrocarbon receptor-mediated activity of atmospheric particulate matter from an urban and a rural site in Switzerland

Atmospheric particulate matter (PM) is an air-suspended mixture of solid and liquid particles that vary in size, shape, and chemical composition. Long-term exposure to elevated concentrations of fine atmospheric particles is considered to pose a health threat to humans and animals. In this context, it has been hypothesized that toxic chemicals such as polycyclic aromatic hydrocarbons (PAHs) play an important role. Some PAHs are known to be carcinogenic and it has been shown that carcinogenic effects of PAHs are mediated by the aryl hydrocarbon receptor (AhR). In this study, PM1 was collected at a rural and an urban traffic site during an intense winter smog period, in which concentration of PM1 often exceeded 50 μg m^?3. We applied an in vitro reporter gene assay (DR-CALUX) to detect and quantify PM1-associated chemicals that induce AhR-mediated gene expression. This activity was expressed as CALUX equivalents of 2,3,7,8-tetrachlorodibenzodioxin (PM-TCDD-CEQs). In addition, concentrations of PAHs in the PM1 extracts were determined using gas chromatography/high-resolution mass spectrometry. Concentrations of PM-TCDD-CEQs ranged from 10 to 85 pg m^?3 and from 19 to 87 pg m^?3 at the urban and rural site, respectively. By the use of known relative potency factors, the measured concentration of a PAH was converted into a PAH-TCDD-CEQ concentration. ΣPAH-TCDD-CEQ and PM-TCDD-CEQ were highly correlated at both sites (r² = 0.90 and 0.69). The calculated ΣPAH-TCDD-CEQs explain between 2% and 20% of the measured PM-TCDD-CEQs. Benzo[k]fluoranthene was the most important PAH causing approximately 60% of the total ΣPAH-TCDD-CEQ activity. In contrast to NO, CO, PM10, and PM1, the concentration of PM-TCDD-CEQs showed no significant difference between the two sites. No indications were found that road traffic emissions caused elevated concentrations of PM-TCDD-CEQs at the urban traffic site.     

The influence of temperature on the deactivation of commercial Pd/Rh automotive catalysts

Automotive catalyst deactivation can be promoted by thermal and poisoning mechanisms. Catalyst efficiency is reduced by thermal degradation resulting in the agglomeration of precious metals and the reduction of the washcoat surface area. In this paper, the temperature influence on the commercial Pd/Rh-based automotive catalyst performance was studied. Textural and physicochemical characterisation techniques were employed, such as X-ray fluorescence (XRF), atomic absorption spectrometry (AAS), N₂ physisorption, X-ray diffraction (XRD), temperature programmed reduction (TPR) and scanning electron microscopy coupled with energy-dispersive X-ray analysis (SEM–EDX). The catalysts were evaluated for CO and propane oxidation with a stoichiometric gas mixture similar to engine exhaust gas. The results indicated the transformation of alumina into high temperature phases and the formation of new mixed oxide phases. Evidence of sintered particles and several spots of palladium agglomerates was seen by SEM–EDX analysis. The activity results showed the effects of thermal deactivation on the conversion of the pollutants. In spite of exposure to extreme temperature conditions (72 h at 1200 °C), significant activity was still observed for carbon monoxide and propane oxidation reactions.     

Toxaphen in der Umwelt

Toxaphene is a mixture of more than 200 polychlorinated C₁₀-terpenes. Due to its persistence and long-range transport, it is distributed all over the world. Many of the components are very stable under environmental conditions, while others are easily degraded by UV-light or microorganisms. The main conversion pathway is reductive dechlorination and dehydrochlorination; oxidative degradation possibly occurs only after previous dechlorination. Accumulation especially in the aquatic environment has led in many cases to high residue levels in fish, marine mammals, and sea birds of the northern hemispere. Toxaphene is mutagenic in the Ames test and of high toxicity for fish, but few data are available on the toxicity of single components or their mode of action.     

Behavior of fenhexamid in soil and water

A study was conducted to investigate fenhexamid (FEX) behavior in soil and in water. FEX proved to be rather stable at acid pH but showed slight degradation at neutral and alkaline pH. After 101 days of FEX spiking of a soil sample, 94% at pH 4, 12% at pH 7 and 23% at pH 9 of the active ingredient was still present. In natural water the rate of FEX disappearance appeared to be slow which may be due to abiotic rather than biotic processes. The soil degradation tests showed low persistence of the active ingredient if a good microflora activity is guaranteed (DT(50) about 1 day). Moreover, in absence of microorganisms, FEX proved to be stable. Humidities of 25 and 50% of Water Holding Capacity (WHC) influenced in equal measure the rate of degradation. From the same soil, a bacterium was isolated and identified as Bacillus megaterium, which was able to metabolize FEX with the hydroxylation of the cyclohexane ring. Moreover, FEX showed an elevated affinity for humic acid (73%), smectite (31%), and ferrihydrite(20%) and low affinity for vermiculite (11%) and kaolinite (7%).     

Distribution of Cd and As in organs and tissues of four marine mammal species stranded along the Italian coasts

Concentrations of Cd and As were determined in organs and tissues (muscle, heart, kidney, lung and liver) of four cetacean species (Stenella coeruleoalba, Truncatus truncatus, Grampus griseus and Ziphius cavirostris) stranded along the Italian coasts during the period 2000-2009. Significant differences were found between Cd concentrations in the different analysed tissues. Particularly, the kidney shows the highest concentrations of Cd in all analysed specimens, followed by the liver. No systematic or statistically significant difference in As concentrations was found in the analysed tissues. Considerable differences of Cd and As values in samples from different geographical areas (Sicily Channel, Adriatic Sea and Tyrrhenian Sea) were found, with the highest values measured in samples from the Sicily Channel. This basically suggests that anthropogenic and natural sources significantly affect Cd and As content in cetaceans.     

Possible markers of traffic-related emissions

Looking for robust indicators of motor vehicle emissions it has been found that brake wear and linings are significant contributors of Cu, Mo and Sb to air particulate matter. These trace elements, whose mutual ratios in airborne particulate matter resulted quite different from those in crustal material, appear to be available fingerprinting tools to identify the contribution of on-road vehicles to traffic-derived particulate matter. In this study, the results of analytical determinations of Cu, Mo and Sb on PM(10), PM(2.5), vegetation and brake dust samples, together with gas (CO, NOx) concentrations, are discussed. Highly significant correlations among Cu, Sb and Mo were observed in particulate matter from Palermo and between Cu-Sb and Cu-Mo at Catania. Further significant positive correlations have been found in pine needles from Palermo, Gela and in platanus leaves from Catania.     

Temporal distribution of cyanobacteria in the coast of a shallow temperate estuary (Río de la Plata): some implications for its monitoring

The aim of this study was to analyze the temporal distribution of phytoplanktonic cyanobacteria in a site located in the freshwater tidal zone near the extraction point for the drinking water supply. Samples were taken considering three timescales as follows: hours, days, and weeks, during the period of highest development of cyanobacteria. The phytoplankton density, microcystin concentration (LR, RR, YR), and chlorophyll-a were related to meteorological variables (wind and temperature), tidal high, and physical-chemical variables (nutrients, pH, conductivity, light penetration). The results obtained in this study showed that the variables that primarily modulate the temporal distribution of cyanobacteria were temperature, pH, light penetration, conductivity, and nutrients (particularly NO₃ ^? and NH₄ ⁺), while the winds and tide had a secondary effect, only evidenced at an hourly scale. Therefore, this timescale would be the most suitable for monitoring cyanobacterial populations, when the amount of cyanobacterial cells exceeds the alert I level proposed by the World Health Organization. This recommendation is particularly important for the water intake zones in Río de la Plata, which are vulnerable to the damage generated by cyanobacteria on the water quality.     

Valorisation of crude earth as sustainable building material: a case of international cooperation in the Logone Valley (Chad–Cameroon)

Deforestation is one of the most dramatic threats to environmental equilibrium and food safety in many regions of the world, and particularly in sub-Saharan Africa. It is enhanced by many kinds of human activities, among which is the earth brick-firing process that needs large amounts of wood for attaining and maintaining temperatures required during this process. In order to reduce deforestation, the present study investigated from different points of view the potential of crude earth to be used as building material, taking as a case study the Logone Valley located at the border between Chad and Cameroon. First, an on-site investigation was made to verify the state-of-the-art of brick production technologies and to evaluate their impact on the environment. Subsequently, morphological and geotechnical analyses on soil samples collected from different sites of the Logone Valley were carried out, to evaluate their suitability to brick production. Finally, a pilot plant for crude earthen brick production was set, particularly based on a new press designed for this purpose.