Reactive and organic halogen species in three different European coastal environments

International audienceWe present results of three field campaigns using active longpath DOAS (Differential Optical Absorption Spectroscopy) for the study of reactive halogen species (RHS) BrO, IO, OIO and I2. Two recent field campaigns took place in Spring 2002 in Dagebüll at the German North Sea Coast and in Spring 2003 in Lilia at the French Atlantic Coast of Brittany. In addition, data from a campaign in Mace Head, Ireland in 1998 was re-evaluated. During these field campaigns volatile halogenated organic compounds (VHOCs) were determined by GC/ECD-ICPMS in air and water. Due to the spatial distribution of macroalgae at the German North Sea Coast we found a clear connection between elevated levels of VHOCs and the appearance of macroalgae. Extraordinarily high concentrations of several VHOCs, especially CH3I and CH3Br of up to 1830 pptv and 875 pptv, respectively, were observed at the coast of Brittany, demonstrating the outstanding level of bioactivity there. We found CH2I2 at levels of up to 20 pptv, and a clear anti-correlation with the appearance of IO. The IO mixing ratio reached up to 7.7±0.5 ppt(pmol/mol) during the day, in reasonable agreement with model studies designed to represent the meteorological and chemical conditions in Brittany. For the two campaigns the DOAS spectra were evaluated for BrO, OIO and I2, but none of these species could be clearly identified (detection limits around 2 ppt, 3 ppt, 20 ppt, resp.). Only in the Mace Head spectra evidence was found for the presence of OIO. Since macroalgae under oxidative stress are suggested to be a further source for I2 in the marine boundary layer, we re-analyzed spectra in the 500?600 nm range taken during the 1998 PARFORCE campaign in Mace Head, Ireland, which had not previously been analyzed for I2. We identified molecular iodine above the detection limit (~20 ppt), with peak concentrations of 61±12 ppt. Since I2 was undetectable during the Brittany campaign, we suggest that iodine may not be released into the atmosphere by macroalgae in general, but only by a special type of the laminaria species under oxidative stress. Only during periods of extraordinarily low water (spring-tide), is the plant exposed to ambient air and may release gaseous iodine in some way to the atmosphere. The result of our re-analysis of spectra from the PARFORCE campaign in 1998 support this theory. Hence, we feel that we can provide an explanation for the different I2 levels in Brittany and Mace Head

Continuous haematic pH monitoring in extracorporeal circulation using a disposable florescence sensing element.

During extracorporeal circulation (ECC), blood is periodically sampled and analyzed to maintain the blood-gas status of the patient within acceptable limits. This protocol has well-known drawbacks that may be overcome by continuous monitoring. We present the characterization of a new pH sensor for continuous monitoring in ECC. This monitoring device includes a disposable fluorescence-sensing element directly in contact with the blood, whose fluorescence intensity is strictly related to the pH of the blood. In vitro experiments show no significant difference between the blood gas analyzer values and the sensor readings; after proper calibration, it gives a correlation of R>0.9887, and measuring errors were lower than the 3% of the pH range of interest (RoI) with respect to a commercial blood gas analyzer. This performance has been confirmed also by simulating a moderate ipothermia condition, i.e., blood temperature 32°C, frequently used in cardiac surgery. In ex vivo experiments, performed with animal models, the sensor is continuously operated in an extracorporeal undiluted blood stream for a maximum of 11 h. It gives a correlation of R>0.9431, and a measuring error lower than the 3% of the pH RoI with respect to laboratory techniques

Observation of mesenteric microcirculatory disturbance in rat by laser oblique scanning optical microscopy

Ischemia-reperfusion (I/R) injury model has been widely applied to the study of microcirculation disturbance. In this work, we used laser oblique scanning optical microscopy (LOSOM) to observe the microcirculation system in the mesentery of rat model. Utilizing a localized point-scanning detection scheme, high-contrast images of leukocytes were obtained. The extended detection capability facilitated both the automatic in vivo cell counting and the accurate measurement of the rolling velocity of leukocytes. Statistical analysis of the different treatment groups suggested that the distinction between I/R and sham groups with time lapse is significant

Studies of Reactive Halogen Species (RHS) in the Marine and mid-Latitudinal Boundary Layer by Active Longpath Differential Optical Absorption Spectroscopy

Untersuchungen von Reaktiven Halogenverbindungen (RHS) in der Maritimen Grenzschicht und in Mittleren Breiten mit der Aktiven Langpfad DOAS Methode Die Relevanz reaktiver Halogenverbindungen in der Troposphare ist einerseits belegt durch den gravierenden Ein uss auf Ozon, welcher zum ersten Mal wahrend des polaren Sonnenaufgangs in der vollstandigen Zerstorung bodennahem Ozons durch reaktive Bromverbindungen beobachtet wurde. Weiterhin werden reaktive Iodverbindungen in Zusammenhang mit aktuell beobachteter Partikelbildung in Kustengebieten gebracht. Da Partikel in der Atmosphare die mikrophysikalischen Eigenschaften von Stratocumulus Wolken beein ussen, kann in diesen Beobachtungen eine groe Bedeutung fur das Klima liegen. Im Rahmen der vorliegenden Arbeit wurden drei Feldmesskampagnen unter Verwendung der aktiven Langpfad DOAS Messmethode durchgefuhrt, um das Vorkommen von reaktiven Halogenverbindungen, speziell BrO, IO, OIO und I2 in verschiedenen mittlereren Breiten zu untersuchen. Wahrend bodengebunder Messungen in der arktisch beein ussten Region der Hudson Bay, Kanada wurden bis zu 35 ppt des BrO Radikals detektiert zeitgleich zur fast vollstandigen Zerstorung des bodennahen Ozons. Bei zwei weiteren Feldmesskampagnen zur Untersuchung der RHS in maritim beein ussten Gebieten an der deutschen Nordseekuste und der franzosischen Atlantikkuste wurde IO als einziges Halogenoxid in beiden Umgebungen gefunden mit maximalen Konzentrationen von 7.70.5 ppt. In dieser maritimen Umgebung konnte BrO nicht oberhalb der Nachweisgrenze von 1.5 ppt nachgewiesen werden, ebenso verblieben OIO und auch I2 unterhalb der Nachweisgrenze. Eine Reanalyse von DOAS Spektren, die wahrend einer vorangegangenen Kampagne 1998 in Mace Head, Irland gewonnen wurden, ergaben 6112 ppt I2 wahrend der Nacht und besonders tiefem Wasserstand wahrend Springtide. Diese Beobachtungen werden erklart unter der Annahme, dass Laminaria Algen, die den unteren Intertidenbereich bewohnen, wahrend dieser Zeit in Kontakt mit der Atmosphare molekulares Iod emittieren

Long term outdoor operation of a tubular airlift pilot photobioreactor and a high rate algal pond as tertiary treatment of urban wastewater.

530 L high rate alga pond (HRAP) and 380 L airlift tubular photobioreactor (TPBR) were operated and compared in a urban wastewater treatment plant (WWTP), with the main purpose of removing nitrogen and phosphorous from the effluent of the WWTP while generating a valuable biomass. The photosynthetic activity in TPBR was during entire experiment higher than HRAP. The maximum areal productivity reached was 8.26 ± 1.43 and 21.76 ± 0.3 g SS m−2 d−1 for HRAP and TPBR respectively. Total nitrogen (TN) removal averaged 89.68 ± 3.12 and 65.12 ± 2.87% for TPBR and HRAP respectively, while for total phosphorus (TP) TPBR and HRAP averaged 86.71 ± 0.61 and 58.78 ± 1.17% respectively. The lipid content showed no significant differences (p < 0.05) between HRAP and TPBR averaging 20.80 ± 0.22 wt%. The main operating disadvantage of TPBR versus HRAP was the sever biofouling which forced to stop the experiment. Under the same conditions of operation TPBR was more limited at low temperatures than HRAP, and HRAP was more light limited than TPBR