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Wet and, to a lesser extent, dry deposition of atmospheric (129)I are known to represent the dominating processes responsible for (129)I in continental environmental samples that are remote from (129)I sources and not directly influenced by any liquid (129)I release of nuclear installations. Up to now, however, little is known about the major emitters and the related global deposition pattern of (129)I. In this work an overview over major sources of (129)I is given, and hitherto unknown time-dependent releases from these were estimated. Total gaseous (129)I releases from the US and former Soviet reprocessing facilities Hanford, Savannah River, Mayak, Seversk and Zheleznogorsk were found to have been 0.53, 0.27, 1.05, 0.23 and 0.14TBq, respectively. These facilities were thus identified as major airborne (129)I emitters. The global deposition pattern due to the (129)I released, depending on geographic latitude and longitude, and on time was studied using a box model describing the global atmospheric transport and deposition of (129)I. The model predictions are compared to (129)I concentrations measured by means of Accelerator Mass Spectrometry (AMS) in water samples that were collected from various lakes in Asia, Africa, America and New Zealand, and to published values. As a result, both pattern and temporal evolution of (129)I deposition values measured in and calculated for different types of environmental samples are, in general, in good agreement. This supports our estimate on atmospheric (129)I releases and the considered substantial transport and deposition mechanisms in our model calculations., (Copyright 2010 Elsevier B.V. All rights reserved.)

Estimates of (129)I depositions from (129)I releases of reprocessing plants are so far based on measurements of soil and rain water samples. Because (129)I concentrations in these samples show a highly temporal and spatial variability, the (129)I deposition values deduced from single measurements cannot be seen as representative for a larger area. Here it is proposed to use lake water as an archive for former (129)I depositions, to overcome these limitations. If the limnological parameters of any lake are known, the local (129)I deposition flux can be deduced which is temporally averaged over the flushing time, and spatially averaged over the catchment area of the lake. Samples were collected from various European lakes and from Lake Baikal (Russia). The (129)I concentration in these samples was measured by means of accelerator mass spectrometry, and values between 0.3 and 8.1x10(8) at/l were obtained. Deduced (129)I deposition fluxes averaged over the flushing times of the lakes range from 0.3 to 9.3x10(12) at/m(2) y. The (129)I deposition fluence measured for Lake Baikal is attributed predominantly to releases from the former Soviet reprocessing facilities Chelyabinsk, Tomsk and Krasnoyarsk, while the (129)I deposition fluxes deduced for all other lakes are attributed to releases from the European reprocessing activities at Sellafield, Marcoule and La Hague.

129I in the European environment originates predominantly from the industrial nuclear fuel reprocessing plants Sellafield (Great Britain), Marcoule, and La Hague (both France). While reliable data on 129I releases from La Hague exist for the whole period of operation, less is known about the contributions from Sellafield and Marcoule. For those periods where no data are available, i.e., for the first 16 years of the Sellafield operation and for the first 3 decades of the Marcoule operation, we estimated releases into the atmosphere of 118 GBq and 825 GBq, respectively. Hence, Marcoule was the major European source of airborne 129I, contributing about 45% to the total airborne 129I releases from all the European reprocessing facilities, until it was decommissioned in 1997. The estimated total emissions were compared with 129I deposition fluxes for the time period 1970-2002, obtained from the analysis of an ice core from Fiescherhorn glacier, Swiss Alps (46 degrees 33'N, 08 degrees 04'E; 3900 m asl). The temporal evolution of the 129I deposition agrees well with the total 129I releases into the atmosphere from the European reprocessing facilities and from atmospheric nuclear weapons tests, supporting our estimated release rates. However,the 129I concentrations and deposition fluxes at Fiescherhorn glacier were a factor of 6 lower than values obtained from the analysis of rainwater collected near Zurich (408 m asl) in Switzerland in the years 1994-97. This suggests a strong vertical concentration gradient of 129I, typical for water-soluble atmospheric trace species which are removed from the atmosphere in the course of days by precipitation scavenging, and must be taken into account if glaciers are used as an archive for a retrospective quantification of 129I deposition fluxes. In addition, the temporal evolution of the contribution of 129I re-emitted from the ocean's surface for the 129I inventory in the atmosphere was quantified for the first time. Although the annual amount of 129I released this way was very low until the early 1990s, it is similar to the airborne 129I releases from Sellafield and La Hague in the present time.

To investigate the potential of physiological lipids as an alternative to synthetic polymeric materials such as poly(lactide-co-glycolide), peptide-containing glyceryl tripalmitate microparticles were prepared. A modified solvent evaporation method and a melt dispersion technique without the use of organic solvent were employed. Thymocartin (TP-4), an immunomodulating tetrapeptide and insulin were chosen as model peptides and incorporated as a solid or dissolved in 100 microl aqueous solution. The resulting microparticles were characterized with respect to particle size and morphology, biocompatibility, drug content (encapsulation efficiency) and in vitro release behavior. Electron spectroscopy for chemical analysis was used to investigate the adsorption of the model peptides to the lipid matrix material. The modified solvent evaporation as well as the melt dispersion method were suitable for the preparation of microparticles in the size range of 20-150 microm with an acceptable yield. The biocompatibility of the glyceryl tripalmitate microparticles after implantation into NMRI-mice was comparable to poly(lactide-co-glycolide) microparticles. The encapsulation efficiency for both model peptides was high (>80%) even at high theoretical loadings when the peptide was incorporated as a solution with the melt dispersion technique. The in vitro release behavior was substantially influenced by the physicochemical properties of the model peptides used in this study.

Somatostatin, a therapeutic peptide with a high therapeutical potential but a very short biological half-live was encapsulated within microparticles by a modified solvent evaporation method and a melt dispersion method without the use of organic solvent. As the use of synthetic polymer matrix materials often goes along with detrimental effects on incorporated peptides, we investigated the potential of physiological lipids such as glyceryl tripalmitate (Dynasan 116) as an alternative matrix material. The two preparation methods were evaluated with respect to surface topography, particle size distribution, encapsulation efficiency, in-vitro release behavior and modification of the resulting microparticles. Microparticles with a suitable particle size distribution for i.m. or s.c. injection could be prepared with both methods. The encapsulation efficiency of the peptide into glyceryl tripalmitate microparticles was substantially influenced by the preparation method and the physical state of the peptide to be incorporated. The melt dispersion technique and the incorporation of the drug as an aqueous solution gave the best results with actual drug loadings up to 9% and an encapsulation efficiency of approximately 90%. Microparticles prepared by the melt dispersion technique crystallized in the unstable alpha-modification. The peptide was released almost continuously over 10 days with no burst effect, 20-30% of the incorporated somatostatin was not released in the monitored time period.