E. Liger

Assessment of ozone variations and meteorological effects in an urban area in the Mediterranean Coast

Ozone concentrations are valuable indicators of possible health and environmental impacts. However, they are also used to monitor changes and trends in the sources of both ozone and its precursors. For this purpose, the influence of meteorological variables is a confusing factor. This study presents an analysis of a year of ozone concentrations measured in a coastal Spanish city. Firstly, the aim of this study was to perceive the daily, monthly and seasonal variation patterns of ozone concentrations. Diurnal cycles are presented by season and the fit of the data to a normal distribution is tested. In order to assess ozone behaviour under temperate weather conditions, local meteorological variables (wind direction and speed, temperature, relative humidity, pressure and rainfall) were monitored together with ozone concentrations. The main relationships we could observe in these analyses were then used to obtain a regression equation linking diurnal ozone concentrations in summer with meteorological parameters.

Gross alpha, gross beta activities and 7Be concentrations in surface air: analysis of their variations and prediction model

Abstract Measurements of gross α, gross β activities and cosmogenic beryllium-7 ( 7 Be ) concentrations were made each week during the years 1992, 1993, 1994 and 1995 from samples of atmospheric aerosols filtered from the air. The data are sufficiently numerous to allow us to examine variations in time and through these measurements we have established several parameters that should be of importance in understanding any trends in radionuclides concentrations in the atmosphere. The weekly variation is discussed in relation to various meteorological factors. Seasonal variation of 7 Be concentration in the atmosphere was measured and there was a tendency for a maximum in the spring and summer and a minimum in fall and winter. It can be said for this radionuclide that our results showed a prevailing influence of weekly average of the daily maximum temperature. In this work, the data on concentrations and meteorological data have been made use of in order to determine a model for gross α, gross β and 7 Be , respectively. The model can be used to estimate that part of the trend in gross α and gross β activities and in 7 Be levels that can be accounted for by trends in local meteorology. A satisfactory agreement between the results of the model and the measurements was highlighted.

Release of 222Rn from some soils

Measurements have been made of 222Rn release from diverse soils in the region surrounding Malaga, Spain. These flux measurements were carried out by two methods. A direct method using a static chamber technique and another indirect method obtained from concentration profile measurements of 222Rn in the soil air. The effects of meteorological variables and other parameters on 222Rn flux were studied. The factors that most affected the instantaneous value of 222Rn release were humidity and soil thermal gradient. The directly measured 222Rn fluxes at investigated sites are higher than 222Rn fluxes derived by the indirect method.

Atmospheric deposition of 7Be at a coastal Mediterranean station

The bulk 7Be depositional flux was measured at Malaga (4°28′8″W; 36°43′40″N), a coastal Mediterranean station in the south of Spain, from 1992 to 1999. The annual 7Be depositional flux varied between 188 and 585 Bq m−2 yr−1 with a mean of 412 Bq m−2 yr−1, reflecting a Mediterranean climate where two well-recognized wet and dry periods are dominant. Data on the 7Be depositional flux in Malaga show that the seasonal variation is not uniform from year to year and the amount of precipitation primarily controls the depositional fluxes. This study shows that the 7Be depositional fluxes during fall and winter were minimized and that the fallout maxima were confined to either spring and/or summer, possibly reflecting stratosphere/troposphere exchange. A comparison of our measurements and other data obtained at different locations in the world was also made.

Measurement of 222Rn in soil concentrations in interstitial air

Measurements of 222RB soil concentrations were made by inserting stainless-steel sampling tubes into the soil. The samples of the soil interstitial air were taken in to pre-evacuated 1 L glass flasks. The glass flasks are cylindrical and coated with a film of ZnS(Ag). Z~Rn was measured by counting the alpha particles emitted by ~Rn and its daughter products, z~SPo and 21aBi, when they reached radioactive equilibrium. Measurements of ZZ2Rn gas concentrations in the soil air interstices by the method at different depths were used to calculate the diffusion coefficient of the Z22Rn in the soil air. This study has been carried out for diverse soils. Copyright

Emissions of CO2 from some soils

Emissions of carbon dioxide were measured from diverse soils in the surroundings of Malaga (Spain). These measurements were carried out by two methods. A direct method using a static open chamber technique and another indirect method obtained from simultaneously measured 222Rn flux and concentration profile measurements of 222Rn and CO2 in the air of soil. The directly measured CO2 fluxes at investigated sites is slightly higher than CO2 fluxes derived from the indirect method. Carbon dioxide emitted by soils, showed a mean direct flux to the atmosphere of 5 mmol M−2 h−1.

Methane uptake in soils of Southern Spain estimated by two different techniques: Static chamber and 222radon flux and soil air concentration profiles

Abstract Measurements of methane fluxes from four differing soils in the surroundings of Malaga (Spain) were carried out by two methods: a direct method using a static accumulation chamber at the soil surface and an indirect method obtained from simultaneously measured 222 Rn flux from the soil surface in parallel with the concentration profile measurements of 222 Rn and CH 4 in the air of soil. The directly measured methane flux at all the investigated soils was higher than the methane fluxes derived from the indirect method. Atmospheric methane was consumed by all the soils and mean direct flux to the atmosphere were 3.25 μmol m −2 h −1 . The study showed no correlation between methane uptake and soil temperature, which might be due to the dry conditions prevailing during the study period.

Gross-α and gross-β activities in airborne particulate samples. Analysis and prediction models

Measurements of gross-a and gross-b activities were made every week during the years 1992‐1997 for airborne particulate samples collected using air filters at a clear site. The data are suAciently numerous to allow the examination of variations in time and by these measurements to establish several features that should be important in understanding any trends of atmospheric radioactivity. Two models were used to predict the gross-a and gross-b activities. A good agreement between the results of these models and the measurements was highlighted. # 2001 Elsevier Science Ltd. All rights reserved.

EFFECT OF CARBONIC ANHYDRASE INHIBITORS ON THE INORGANIC CARBON UPTAKE BY PHYTOPLANKTON NATURAL ASSEMBLAGES(1).

The role of carbonic anhydrase (CA) in inorganic carbon acquisition (dissolved inorganic carbon, DIC) was examined in Alboran Sea phytoplankton assemblages. The study area was characterized by a relatively high variability in nutrient concentration and in abundance and taxonomic composition of phytoplankton. Therefore, the relationship between environmental variability and capacity for using HCO3− via external CA (eCA) was examined. Acetazolamide (AZ, an inhibitor of eCA) inhibited the primary productivity (PP) in 50% of the samples, with inhibition percentages ranging from 13% to 60%. The AZ effect was more prominent in the samples that exhibited PP >1 mg C · m−3 · h−1, indicating that the contribution of eCA to the DIC photosynthetic flux was irrelevant at low PP. The inhibition of primary productivity by AZ was significantly correlated to the abundance of diatoms. However, there was no a relationship between AZ effect and CO2 partial pressure (pCO2) or nutrient concentration, indicating that the variability in the PP percentage supported by eCA was mainly due to differences in taxonomic composition of the phytoplankton assemblages. Ethoxyzolamide (EZ, an inhibitor of both external and internal CA) affected 13 of 14 analyzed samples, with PP inhibition percentages varying from 50% to 95%. The effects of AZ and EZ were partially reversed by doubling DIC concentration. These results imply that CA activity (external and/or internal) was involved in inorganic carbon acquisition in most the samples. However, EZ effect was not correlated with pCO2 or taxonomic composition of the phytoplankton.

7Be and 210Pb concentrations in air in Málaga (Spain)

Measurements of 7Be and 210Pb in atmospheric air (1 m above the ground) have been carried out each week over one and a half year period. The method used to determine 7Be and 210Pb activities is based on the total amount of radioactive aerosols filtered from the air. The activities of 7Be and 210Pb were determined by a hyper-pure germanium detector using standard gamma-spectrometry. The average weekly concentrations of 7Be were in the range of 1.21-12.1 mBq.m-3 and for 210Pb in the range of 0.8-2.4 mBq.m-3. The weekly variations were discussed in relation to various meteorological factors. It can be said that our results showed a prevailing influence of weekly average temperature for 7Be concentration and the weight of aerosols and wind speed for 210Pb oncentrations.