Pb Activity Ratios Research Articles

A study on possible use of Urtica dioica (common nettle) plant as polonium (210)Po and lead (210)Pb contamination biomonitor in the area of phosphogypsum stockpile.

The aim of this study was to test a possible use of Urtica dioica (common nettle) plant as a biomonitor of polonium 210Po and lead 210Pb contamination near phosphogypsum stacks by determining concentrations of these radionuclides in samples collected from the area of phosphogypsum stockpile in Wiślinka (northern Poland). The 210Po and 210Pb contents in roots depended on their concentrations in soils. Bioconcentration factor values from soil to root of the plant did not depend on 210Po and 210Pb contents in soils that leads to the conclusion that different polonium and lead species have different affinities to U. dioica plants. The main sources of both analyzed radionuclides in green parts of plants are wet and dry air deposition and transportation from soil. The values of 210Po/210Pb activity ratio indicate natural origin of these radioisotopes in analyzed plants. 210Po and 210Pb concentration in U. dioica roots is negatively weakly correlated with distance from phosphogypsum stockpile.

雨水中214Bi/214Pb放射能比による雲粒・雨滴の存在時間の推定

雨水中214Bi/214Pb放射能比による雲粒・雨滴の存在時間の推定

Resuspension of radionuclides into the atmosphere due to forest fires

Two major wild fire episodes occurred in north- western Russia in April/May and August 2008. The burning biomass and heating of the surface soil released several hazardous components into the atmosphere. During the spring smoke episode the 137 Cs activity concentration in the air in southern Finland increased by a factor of 10 compared to values just before the episode. Simultaneously there was an increase of a same order of magnitude in the concentra- tions of PM10, trace metals (e.g. lead), polycyclic aromatic hydrocarbons (e.g. benzo(a)pyrene) and potassium. The 210 Po/ 210 Pb activity ratio increased from the usual 3-5% to even as high as 35% because Po is more volatile than Pb. The summer episode was less severe but still the mercury concentration in the air increased by a factor of two while 137 Cs activity concentration rose by a factor of eight. From the radiological point of view the exposure to the increased radionuclide concentration was insignificant compared to health hazards due to the increased concentration of aerosol particles and their chemical components.

Natural radionuclides in fine aerosols in the Pittsburgh area

Natural radionuclides have been proposed for use as tracers in assessing the transport of ozone and aerosols in the troposphere. Beryllium-7 is produced in the upper troposphere and lower stratosphere and after formation rapidly attaches itself to fine aerosol particles. Measurements of 7 Be at ground level can therefore be used as a tracer of stratospheric/tropospheric folding events, leading to injection of ozone and upper atmospheric aerosols into the lower atmosphere. Since its concentration varies little on regional scales it can also be used to detect and correct for sampling problems in particulate monitoring networks. Lead-210 and its progeny, 210 Bi, and 210 Po can also be used to determine the apparent tropospheric residence times for fine aerosols by looking at the 210 Bi/ 210 Pb and 210 Po/ 210 Pb activity ratios. Reported here are measurements of the natural radionuclides 7 Be and 210 Pb, taken at two sites near Pittsburgh, PA in the summer of 2001 and at a site near Centerton, New Jersey in 1999 during the NEOPS field campaign. Beryllium-7 results show no evidence of upper atmospheric input during the sampling period. Apparent residence times as calculated from 210 Po/ 210 Pb ratios are shorter for Pittsburgh than for Centerton, and shorter for both sites than those obtained previously in other areas, indicating a local aerosol source as well as a higher loading of water-soluble species such as sulfate and nitrate. A comparison of fine and course aerosol lifetimes shows no contribution of excess 210 Po from wind-blown soil or from coal-fired power plants.

Aerosols: unexpected disequilibrium phenomena between airborne radio activities of lead-210 and its progenies bismuth-210 and polonium-210.

For the first time, concentrations of the long lived radon progenies (210)Pb, (210)Bi and (210)Po were measured in the mine atmosphere of the so called "healing gallery" in Badgastein, Austria, a region famous for its radioactive springs. These investigations were performed in order to study the radioactive equilibrium between the (210)Pb-(210)Bi and the (210)Pb-(210)Po pairs so as to gain more information about the aerosol-forming processes in the mine. The particle size distribution of the aerosols was determined under different ventilation conditions. Six-stage and eight-stage cascade impactors with working ranges from 0.15 to 5 micro m and from 0.063 to 8 micro m, respectively, were used to collect the mine aerosols. These samples were analysed in the laboratory and measured by liquid scintillation spectrometry. The most surprising results were found under full ventilation, when the total activity concentrations of (210)Pb, (210)Bi and (210)Po were 4.6, 2.0 and 16.5 mBq/m(3), respectively. In this case (210)Po/(210)Pb activity ratios ranged between 1.8+/-0.3 and 4.3+/-0.3. These unexpected results were confirmed by the eight-stage impactor samples. For the smallest particles, between 0.062 and 0.125 micro m, an even higher value of 7.5 was observed. As outside sources could be excluded, such (210)Po enrichments must occur during the aerosol-forming process itself inside the mine.

Factors controlling [formula omitted] and [formula omitted] atmospheric deposition as revealed by sampling individual rain events in the region of Geneva, Switzerland

Bulk atmospheric deposition of 7 Be and 210 Pb has been measured at Versoix, close to Geneva, Switzerland. Collectors were continuously deployed from November 1997 through November 1998 for periods from 1 to 22 days depending on the frequency of rain. The activities of 7 Be and 210 Pb integrated over the sampling interval were moderately well correlated with rainfall ( r 2 of 0.66 and 0.55, respectively; p<0.001) and well correlated one with the other ( r 2 of 0.91; p<0.001). The 7 Be/ 210 Pb activity ratio is close to 13.5, except for samples collected in the periods of very low precipitation which have a distinctly lower ratio. A simple model accounting for rainfall, seasonal variations and reload of the local atmosphere after a rain event explains 90% of the variance of 7 Be and 210 Pb deposition. Concentrations of 210 Pb and Ca ++ in rain were correlated with transport time of air masses over the continent as indicated by reconstruction of air mass trajectories over three days.

Tissue and subcellular distributions of [formula omitted] in the crustacean Saduria entomon inhabiting the southern Baltic Sea

The paper presents the results of 210 Po determinations, and 210 Po/ 210 Pb activity ratios, in the tissues and organs of the Baltic crustacean Saduria entomon. Additionally, the subcellular localisation of 210 Po in the hepatopancreas of this organism has been studied using centrifugation followed by determination of the 210 Po concentrations in isolated fractions. The 210 Po concentrations fall within the range 0.63–543.5 Bq kg −1 (dry wt). The highest values of 210 Po and 210 Po/ 210 Pb activity ratio (10.6) were found, as expected, in the hepatopancreas. The majority of the 210 Po in the hepatopancreatic cells was found in the cytosol fraction (60% of the total 210 Po ).

A comparison of [formula omitted] accumulation in molluscs from the southern Baltic, the coast of Spitsbergen and Sasek Wielki Lake in Poland

210 Po was analysed in the tissues and organs of four different species of molluscs originating from the Gulf of Gdańsk and Słupsk Narrow ( Mytilus trossulus, Mya arenaria), Southern coast of Spitsbergen ( Chlamys islandicus), and Sasek Wielki Lake in north-east Poland ( Anodonta cygnea). The results show a great disproportion in the 210 Po distribution within the molluscs examined. The highest 210 Po concentrations were found in the hepatopancreas of the Baltic and freshwater species whereas for the polar molluscs the highest values were observed in gills. The 210 Po/ 210 Pb activity ratio was calculated exclusively for the Baltic bivalves. The value of the ratio greatly exceeds unity for all organs and tissues (except for the shell of Mya arenaria). The concentration factor CF for the total soft tissue of all the molluscs analysed varies in the range of 3600–72,000.

Formula omitted] and [formula omitted] in the South-equatorial Atlantic: : distribution and disequilibrium in the Upper 500 m

The distribution of 210 Po and 210 Pb (grand daughter–parent) in the dissolved and total (dissolved+particulate) phase of sea water samples has been measured in the upper 500 m at four stations along a western transect in the South-equatorial Atlantic. Such a transect allows one to make inference about the particle-associated scavenging processes in the equatorial versus subtropical regions of the South Atlantic. A common feature of the 210 Po profiles is that the dissolved activities in the surface waters are about one-third of the equilibrium concentrations, suggesting weeks to a month removal times of 210 Po by adsorption on settling particles. The mean dissolved 210 Po / 210 Pb activity ratios in the equatorial and South Atlantic are 0.27 and 0.39, respectively, representing a pronounced disequilibrium in surface waters. The box-model calculation yields a residence time of about 73 and 130 days for dissolved 210 Po in the surface water at the equatorial and southern sites, respectively. The gross deficiency of 210 Po extends throughout the upper 500 m; however, the 210 Po residence time in the intermediate depths is longer than that in surface water. The observed 210 Po – 210 Pb disequilibrium has been examined with respect to POC concentration, which yields a significant positive correlation ( r 2=0.61), suggesting that the 210 Po deficiency is mainly associated with biological removal. The 210 Pb distribution shows distinctively higher concentrations in the equatorial surface waters (19–22 dpm/100 l), suggesting an enhanced atmospheric flux of 210 Pb . The residence time of dissolved 210 Pb (400–780 days), with respect to atmospheric input, is longer than dissolved 210 Po and 234 Th residence times, and also shows a latitudinal decrease toward the equator in the surface ocean. The shorter residence time in the surface equatorial ocean (0–20 m) seems associated with higher productivity and more rapid particulate scavenging.

Model of &lt;sup&gt;210&lt;/sup&gt;Pb and &lt;sup&gt;210&lt;/sup&gt;Po Placental Transfer to Fetal Bone

Because of the paucity of actual measurements, a theoretical model has been developed that predicts the in utero activity levels of 210 Po ingrowing from 210 Pb. Experimental data have shown that the placental transfer of lead takes place precludes the transfer of significant amounts of polonium. Bone volume seekers with long half-lives that can substitute for calcium, such as 210 Pb, are assumed to have similar specific activities, per g Ca, in fetal bone as they have in maternal bone. The dependence of the ingrowth of 210 Po from 210 Pb with gestational age was calculated with the input of experimental data on the mass of stable lead and calcium in the fetal skeleton and the whole body. It is predicted that the 210 Po/ 210 Pb activity ratio is ∼ 0.25 in the bone of the third-trimester fetus

The use of natural radioactive tracers in a study of atmospheric residence times

The global values of the activity ratios of 7 Be/ 32 P, 7 Be/ 35 S, and 7 Be/ 22 Na are presented and discussed. The wide range of variations of these observed ratios and residence times derived from them indicate a varying input of a stratospheric component of these isotopes. This shows that the troposphere is not a closed system and residence times calculated from the above ratios are likely to be larger than the actual values. More consistent results are obtained for tropospheric residence times based on 210 Bi/ 210 Pb activity ratios from various locations. The 7 Be/ 35 S ratios are lower than the expected ratios by a factor of 2 to 3, calculated from cosmic ray production values, indicating other sources like bomb production. Since the ratios are less even during periods of low fallout activity, another source, such as graphite reactors is a possibility. DOI: 10.1034/j.1600-0889.1990.00014.x