In the assessment of the environmental distribution of technetium (99 Tc) the transfer factor or bioconcentration factor is an important parameter.Generally the transfer factor is based on (pseudo) equilibria, first-orderuptake and elimination processes, and an absence of homeostatic control. Thepresent work evaluates the transfer factor concept for Tc in duckweed by evaluatingTc steady-state concentrations in duckweed against growth rate and nutrientconcentration. It was concluded that (1) Tc accumulation is not homeostaticallycontrolled and (2) the transfer factor is inversely proportional to the growthrate.
Transplants of the lichen Parmelia sulcata were suspended in nylonbags in a region within a rectangle of 15 km wide and 25 km long on a grid2.5 km × 2.5 km, centred in a oil powered station. In each of the 47places, two sets of four transplants each were hung in a system that rotatesaccording to the wind direction. One set was always facing the wind and theother downwind. Every three months for a 9-month period one transplant fromeach set was collected. The transplants were analysed by instrumental neutronactivation analysis (INAA) and proton induced X-ray emission (PIXE). The transplantbehavior according to the different exposure to the wind is investigated,and some emission sources are identified.
Two examples are given to illustrate how modern experimental techniques may extend the scope of possibilities of radiotracer applications. The first example refers to the use of a Ge-detector -ray spectrometer to measure the transport in plants of 15 elements simultaneously. The second example presented is an in-vivo study of the binding of Cd-ions in plants using meansurements of perturbed --directional correlations.
Between 8th July 2002 and 18th June 2004, aerosol samples were collected in Azores. Their inorganic composition was obtained
by neutron activation analysis in order to study the differences of aerosols in two atmospheric altitudes of the central north
Atlantic: (1) PICO-NARE observatory (Lower Free Troposphere-LFT) at Pico mountain summit (38,470ºN, 28,404ºW, 2,225 m a.s.l.)
in Pico Island, Azores, where air masses from the surrounding continents (Africa, Europe, Central and North America) pass
through, carrying aerosols with anthropogenic (Sb, Br, Mo, U, Se and Tb) and/or natural emissions (Fe, Co, La, Na, Sm, Cr,
Zn, Hf, K and Th); (2) TERCEIRA-NARE station (Marine Boundary Layer) at Serreta (38,69ºN, 27,36ºW, 50 m a.s.l.), in Terceira
Island, Azores, where natural aerosols (I, Cl, Na, Br and other soil related elements) are predominant. However, a combined
interpretation of the data points out to a co-existence of the anthropogenic elements Sb and Mo, eventually with similar origins
as the ones passing Pico Mountain summit. Very high concentrations and enrichment factors for Sb, Mo and Br in LFT, higher
than the ones found in other areas, confirm atmospheric long-range transport mainly from the west boundary of north Atlantic;
this may indicate eventual accumulation and persistence of those elements in the area due to the presence of Azores high pressures
or the Hadley cells effect. A significant correlation between Fe and Yb and the enrichment of rare earth elements (La, Sm,
Tb and Yb) and Th in LFT aerosols, both reflect a mineral dust intrusions from north Africa (Sahara and Sahel region).
Authors:Kamalika Sen, Wouter Breeman and H. Wolterbeek
The present article describes the probable speciation of 68Ga radionuclide just before labeling to DOTA peptides for PET imaging. The 68Ga eluted from an anion exchange column after its purification was analyzed for its elemental composition and pH at several
stages. Neutron activation analysis of the eluted fractions yields the concentrations of Na and Cl, pH measurements indicate
the concentration of free H+ ions in the medium and specific activity calculations indicate the concentration of 68Ga in the solution. Using all these information we get the idea of speciation of no carrier added Ga in the eluted fractions
from CHEAQS programme. The estimations indicate that Ga is mostly present as GaCl2+ in the total MiliQ eluate. However, just before labeling of DOTA the pH of the Ga-containing eluate is adjusted to ~3.5 using
HEPES buffer and at that condition Ga remains as Ga3+ species which is responsible for a successful and efficient labeling. The MilliQ eluate collected before actual labeling
was estimated for trace elements using inductively coupled plasma atomic emission spectrometry was found to contain a few
ppb of Al, Co, Pd and Pt that did not interfere in the actual labeling. A clear idea about the prerequisite of 68Ga species before labeling to a peptide might be of special interest for its judicious application as a radiopharmaceutical.
Authors:M. Freitas, M. Reis, A. Marques and H. Wolterbeek
Transplants of the lichen Parmelia sulcata Taylor were suspended in nylon bags within a rectangle of 15 km wide and 25 km long on a grid 2.5 km×2.5 km, centered in a power station. In all of the 47 places two sets of four transplants each were hanged, one facing the wind and the other opposing the wind. Care was taken (1) in covering the two sets with a polyethylene roof to prevent leaching of elements in the lichen, (2) in building a hanging system that could rotate according to the wind direction, and (3) in orienting one set towards the wind and the other set opposite the wind. During a one-year period, one transplant of each set was taken for analysis after a 3 month exposure. Some results of the second campaign (after a 6 month exposure) obtained by INAA are shown and compared with the first campaign (after a 3 month exposure). Elemental contents are mapped and discussed.
Authors:J. Hattink, L. Weltje, H. Wolterbeek and J. de Goeij
This study deals with the accumulation dynamics of the long-lived fission product technetium (99Tc) in duckweed. Duckweed serves as model for aquatic plants, because of its representative foliar uptake for 99Tc. This study shows that 99Tc is irreversibly accumulated and distributed over cytoplasm, chloroplasts and mitochondria. Autoradiography showed that 99Tc was not transported to new biomass. Irreversible storage of 99Tc in plant biomass means that steady-state situations cannot be interpreted as a balance between uptake and elimination of 99Tc, but that 99Tc continuously builds up in each single duckweed plant and overall Tc concentrations are averaged over new biomass.
Authors:A. Marques, M. Freitas, M. Reis, H. Wolterbeek and T. Verburg
Transplants of the epiphytic lichen Parmelia sulcata were suspended in nylon bags within a rectangle of 15 km wide and 25 km long on a grid 2.5 km'2.5 km in the Sado estuary region. The transplants were oriented towards the wind (F) and opposing the wind (T) and were collected after 3, 6 and 9 months of exposure. Samples were analyzed by INAA and PIXE. Source identification was made by Monte Carlo Target Transformation Factor Analysis (MCTTFA) using three different combinations of data (all data, F data and T data). Five factors were identified for all the combinations performed. For two factors, F and T differentiation was observed.
Authors:R. Jasan, T. Verburg, H. Wolterbeek, R. Plá and M. Pignata
The lichen Ramalina celastri (Spreng.) Krog. & Swinsc. was used to study trace-element atmospheric pollution in Córdoba (Argentina). 38 samples from a 1999 campaign were analyzed by NAA and a number of physiological parameters was determined. In first-ever comparisons, no correlations were found between altitude, physiological parameters and determined elements, which allowed the full comparison of element data in lichen samples throughout the whole survey area. After the application of Monte Carlo assisted factor analysis to the elemental matrix, five source profiles were found and mapped. The attribution of the sources is discussed.
Authors:A. Marques, M. Freitas, H. Wolterbeek and T. Verburg
Parmelia sulcata transplants were used in three different exposure systems, focused on three different influxes: free influx, horizontal influx
and vertical influx. The total element deposition and the precipitation volumes were found to be positively correlated for
Fe and Ni only. The element contents in lichen transplants and in total element deposition showed significant correlations
for Ca, Fe and Mn in the free influx system and for Na, Ni and V in the horizontal influx system. No significant positive
correlations were found for the vertical influx. The results indicate that, apart from response rates, the transplant positioning
systems may have effects on element-specific net accumulation.