New particle formation at a peri-urban agricultural site.

New Particle Formation (NPF) is a major source of ultrafine particles that affect both air quality and climate. Despite emissions from agricultural activities having a strong potential to lead to NPF, little is known about NPF within agricultural environments. The aim of the present study was to investigate the occurrence of NPF events at an agricultural site, and any potential relationship between agricultural emissions and NPF events. A field campaign was conducted for 3 months at the FR-Gri-ICOS site (France), at an experimental farm 25 km west of Paris city centre. 16 NPF events have been identified from the analysis of particle number size distributions; 8 during the daytime, and 8 during the night-time. High solar radiation and ozone mixing ratios were observed during the days NPF occurred, suggesting photochemistry plays a key role in daytime NPF. These events were also associated with higher levels of VOCs such as isoprene, methanol, or toluene compared to non-event days. However, ammonia levels were lower during daytime NPF events, contributing to the hypothesis that daytime NPF events were not related to agricultural activities. On the other hand, temperature and ozone were lower during the nights when NPF events were observed, whereas relative humidity was higher. During these nights, higher concentrations of NO2 and ammonia were observed. As a result, agricultural activities, in particular the spreading of fertiliser on surrounding crops, are suspected to contribute to night-time NPF events. Finally, all the identified NPF events were also observed at SIRTA monitoring station 20 km from the FR-Gri ICOS site, showing that both night-time and daytime NPF events were regional processes. We hypothesise that night-time NPF may be related to fertiliser spreading over a regional scale, as opposed to the local activities at the farm. To our knowledge, this is the first time night-time NPF has been observed in the agricultural context.

A multiresidue analytical method on air and rainwater for assessing pesticide atmospheric contamination in untreated areas.

The use of pesticides in agriculture to protect crops against pests and diseases generates environmental contamination. The atmospheric compartment contributes to their dispersion at different distances from the application areas and to the exposure of organisms in untreated areas through dry and wet deposition. A multiresidue analytical method using the same TD-GC-MS analytical pipeline to quantify pesticide concentrations in both the atmosphere and rainwater was developed and tested in natura. A Box-Behnken experimental design was used to identify the best compromise in extraction conditions for all 27 of the targeted molecules in rainwater. Extraction yields were above 80% except for the pyrethroid family, for which the recovery yields were around 40-59%. TD-GC-MS proved to be a good analytical solution to detect and quantify pesticides in both target matrices with low limits of quantification. Twelve pesticides (six fungicides, five herbicides and one insecticide) were quantified in rainwater at concentrations ranging from 0.5 ng·L-1 to 170 ng·L-1 with a seasonal effect, and a correlation was found between the concentrations in rainwater and air. The calculated cumulative wet deposition rates are discussed regarding pesticide concentrations in the topsoil in untreated areas for some of the studied compounds.

Characterization of particulate and gaseous pollutants from a French dairy and sheep farm.

Agricultural activities highly contribute to atmospheric pollution, but the diversity and the magnitude of their emissions are still subject to large uncertainties. A field measurement campaign was conducted to characterize gaseous and particulate emissions from an experimental farm in France containing a sheep pen and a dairy stable. During the campaign, more than four hundred volatile organic compounds (VOCs) were characterized using an original combination of online and off-line measurements. Carbon dioxide (CO2) and ammonia (NH3) were the most concentrated compounds inside the buildings, followed by methanol, acetic acid and acetaldehyde. A CO2 mass balance model was used to estimate NH3 and VOC emission rates. To our knowledge, this study constitutes the first evaluation of emission rates for most of the identified VOCs. The measurements show that the dairy stable emitted more VOCs than the sheep pen. Despite strong VOC and NH3 emissions, the chemical composition of particles indicates that gaseous farm emissions do not affect the loading of fine particles inside the farm and is mainly explained by the low residence time inside the buildings. The experimental dataset obtained in this work will help to improve emissions inventories for agricultural activities.

Automated Plasmodium detection by the Sysmex XN hematology analyzer.

BACKGROUND: Malaria is a potentially severe disease affecting nearly 200 million people per year. Early detection of the parasite even in unsuspected patients remains the challenging aim for effective patient care. Automated complete blood counts that are usually performed for any febrile patient might represent a tool to ascertain malaria infection. AIMS: To evaluate the ability of the new generation of the Sysmex hematology analyzer (XN-series) to detect malaria. METHODS: We retrospectively studied 100 blood samples performed with the recent Sysmex XN analyzer that were positive for Plasmodium and explored its ability to detect the parasite. 100 samples from patients uninfected by malaria were used as control group. RESULTS: Specific abnormalities such as additional events in the mature neutrophil/eosinophil area of the white blood cells differential (WDF) scattergram were noted for 1.1% of Plasmodium falciparum samples and 56.2% of other Plasmodium species samples. Mature parasite stages (schizonts or gametocytes) were observed on blood smears among those samples. WDF scattergrams were able to detect 80.0% (12/15) of Plasmodium mature stages. Furthermore, the differential in white blood counts between WDF and white cell nucleated (WNR) channels was a predictive signal of Plasmodium mature stages in 73.3% (11/15) of samples and may be explained by a differential destruction of particles with the analyzer reagent. CONCLUSION: Associated to thrombocytopaenia, a Sysmex XN Plasmodium pattern may represent a useful warning for Plasmodium detection in unsuspected patients, particularly when mature parasite stages are present.

Fungicide volatilization measurements: inverse modeling, role of vapor pressure, and state of foliar residue.

Few data sets of pesticide volatilization from plants at the field scale are available. In this work, we report measurements of fenpropidin and chlorothalonil volatilization on a wheat field using the aerodynamic gradient (AG) method and an inverse dispersion modeling approach (using the FIDES model). Other data necessary to run volatilization models are also reported: measured application dose, crop interception, plant foliage residue, upwind concentrations, and meteorological conditions. The comparison of the AG and inverse modeling methods proved the latter to be reliable and hence suitable for estimating volatilization rates with minimized costs. Different diurnal/nocturnal volatilization patterns were observed: fenpropidin volatilization peaked on the application day and then decreased dramatically, while chlorothalonil volatilization remained fairly stable over a week-long period. Cumulated emissions after 31 h reached 3.5 g ha(-1) and 5 g ha(-1), respectively (0.8% and 0.6% of the theoretical application dose). A larger difference in volatilization rates was expected given differences in vapor pressure, and for fenpropidin, volatilization should have continued given that 80% of the initial amount remained on plant foliage for 6 days. We thus ask if vapor pressure alone can accurately estimate volatilization just after application and then question the state of foliar residue. We identified adsorption, formulation, and extraction techniques as relevant explanations.

Human herpesvirus 6 infection and transient acquired myelodysplasia in children.

BACKGROUND: To demonstrate that primary human herpesvirus 6 (HHV-6) infection in childhood can cause hematopoietic dysplasia that mimics a myelodysplastic syndrome (MDS) in severe cases. PROCEDURE: Seven immunocompetent children, who presented at admission with concomitant cytopenias in blood and morphologic features of dysplasia in bone marrow, were evaluated. Diagnosis of acute HHV-6 infection was secondary made by detection of HHV-6 DNA in plasma, bone marrow, or cerebrospinal fluid and measurement of plasma antibody titers. Peripheral blood and bone marrow aspirate smears were examined at diagnosis and during follow-up. Morphologic recognition of myelodysplasia was made according to the recommendations of the Third MIC Cooperative Group. RESULTS: Anemia was the most frequent cytopenia (five of seven cases). Bi- or tri-lineage dysplasia was observed in the marrow samples. Granulocytic and erythroid cells were always affected with dysgranulopoiesis and dyserythropoiesis scores equal to or higher than 3. Myelodysplasia was not due to a clonal disorder and disappeared gradually within 1 or 2 months. CONCLUSIONS: Our results indicate that severe HHV-6 infection may induce reversible myelodysplastic changes. These findings contribute to elucidate the pathogenicity of HHV-6 and furthermore suggest that HHV-6 infection must also be considered as a cause of dysplasia in the differential diagnosis of MDS.

Varations in maize pollen emission and deposition in relation to microclimate.

The coexistence of genetically modified (GM) crops with conventional crops has become a subject of debate and inquiry. Maize (Zea mays L.) is one of the most cultivated crop plants in the world and there is a need to assess the risks of cross-pollination. Concentration and deposition rate downwind from different-sized maize crops were measured during three flowering seasons, together with micrometeorological conditions in the surrounding environment. Pollen release started once the air vapor pressure deficit (VPD) increases above 0.2 to 0.5 kPa. Moreover, the dynamics of release was correlated with the dynamics of VPD surrounding the tassels. Horizontal deposition appeared to follow a power law over short distance downwind from the source, and the dispersal distance increased with the source canopy height and the roughness length of the downwind canopy. This work also provides a data set containing both pollen measurements and contrasting weather conditions to validate dispersal models and further investigate maize pollen dispersal processes.