Absolute dating of the European Neolithic using the 5259 BC rapid 14C excursion

Abrupt radiocarbon (14C) excursions, or Miyake events, in sequences of radiocarbon measurements from calendar-dated tree-rings provide opportunities to assign absolute calendar dates to undated wood samples from contexts across history and prehistory. Here, we report a tree-ring and 14C-dating study of the Neolithic site of Dispilio, Northern Greece, a waterlogged archaeological site on Lake Kastoria. Findings secure an absolute, calendar-dated time using the 5259 BC Miyake event, with the final ring of the 303-year-long juniper tree-ring chronology dating to 5140 BC. While other sites have been absolutely dated to a calendar year through 14C-signature Miyake events, Dispilio is the first European Neolithic site of these and it provides a fixed, calendar-year anchor point for regional chronologies of the Neolithic.

Local incomplete combustion emissions define the PM2.5 oxidative potential in Northern India

The oxidative potential (OP) of particulate matter (PM) is a major driver of PM-associated health effects. In India, the emission sources defining PM-OP, and their local/regional nature, are yet to be established. Here, to address this gap we determine the geographical origin, sources of PM, and its OP at five Indo-Gangetic Plain sites inside and outside Delhi. Our findings reveal that although uniformly high PM concentrations are recorded across the entire region, local emission sources and formation processes dominate PM pollution. Specifically, ammonium chloride, and organic aerosols (OA) from traffic exhaust, residential heating, and oxidation of unsaturated vapors from fossil fuels are the dominant PM sources inside Delhi. Ammonium sulfate and nitrate, and secondary OA from biomass burning vapors, are produced outside Delhi. Nevertheless, PM-OP is overwhelmingly driven by OA from incomplete combustion of biomass and fossil fuels, including traffic. These findings suggest that addressing local inefficient combustion processes can effectively mitigate PM health exposure in northern India.

"Until death do us part". A multidisciplinary study on human- Animal co- burials from the Late Iron Age necropolis of Seminario Vescovile in Verona (Northern Italy, 3rd-1st c. BCE)

Animal remains are a common find in prehistoric and protohistoric funerary contexts. While taphonomic and osteological data provide insights about the proximate (depositional) factors responsible for these findings, the ultimate cultural causes leading to this observed mortuary behavior are obscured by the opacity of the archaeological record and the lack of written sources. Here, we apply an interdisciplinary suite of analytical approaches (zooarchaeological, anthropological, archaeological, paleogenetic, and isotopic) to explore the funerary deposition of animal remains and the nature of joint human-animal burials at Seminario Vescovile (Verona, Northern Italy 3rd-1st c. BCE). This context, culturally attributed to the Cenomane culture, features 161 inhumations, of which only 16 included animal remains in the form of full skeletons, isolated skeletal parts, or food offerings. Of these, four are of particular interest as they contain either horses (Equus caballus) or dogs (Canis lupus familiaris)-animals that did not play a dietary role. Analyses show no demographic, dietary, funerary similarities, or genetic relatedness between individuals buried with animals. Isotopic data from two analyzed dogs suggest differing management strategies for these animals, possibly linked to economic and/or ritual factors. Overall, our results point to the unsuitability of simple, straightforward explanations for the observed funerary variability. At the same time, they connect the evidence from Seminario Vescovile with documented Transalpine cultural traditions possibly influenced by local and Roman customs.

Fossil and Nonfossil Sources of Winter Organic Aerosols in the Regional Background Atmosphere of China

Carbonaceous aerosols (CA) from anthropogenic emissions have been significantly reduced in urban China in recent years. However, the relative contributions of fossil and nonfossil sources to CA in rural and background regions of China remain unclear. In this study, the sources of different carbonaceous fractions in fine aerosols (PM2.5) from five background sites of the China Meteorological Administration Atmosphere Watch Network during the winter of 2019 and 2020 were quantified using radiocarbon (14C) and organic markers. The results showed that nonfossil sources contributed 44-69% to total carbon at these five background sites. Fossil fuel combustion was the predominant source of elemental carbon at all sites (73 ± 12%). Nonfossil sources dominated organic carbon (OC) in these background regions (61 ± 13%), with biomass burning or biogenic-derived secondary organic carbon (SOC) as the most important contributors. However, the relative fossil fuel source to OC in China (39 ± 13%) still exceeds those at other regional/background sites in Asia, Europe, and the USA. SOC dominated the fossil fuel-derived OC, highlighting the impact of regional transport from anthropogenic sources on background aerosol levels. It is therefore imperative to develop and implement aerosol reduction policies and technologies tailored to both the anthropogenic and biogenic emissions to mitigate the environmental and health risks of aerosol pollution across China.

Summer paleohydrology during the Late Glacial and Early Holocene based on δ2H and δ18O from Bichlersee, Bavaria

Isotope-based records provide valuable information on past climate changes. However, it is not always trivial to disentangle past changes in the isotopic composition of precipitation from possible changes in evaporative enrichment, and seasonality may need to be considered. Here, we analyzed δ2H on n-alkanes and δ18O on hemicellulose sugars in sediments from Bichlersee, Bavaria, covering the Late Glacial and Early Holocene. Our δ2Hn-C31 record documents past changes in the isotopic composition of summer precipitation and roughly shows the isotope pattern known from Greenland. Both records show lower values during the Younger Dryas, but at Bichlersee the signal is less pronounced, corroborating earlier suggestions that the Younger Dryas was mainly a winter phenomenon and less extreme during summer. δ18Ofucose records the isotopic composition of the lake water during summer and is sensitive to evaporative enrichment. Coupling δ2Hn-C31 and δ18Ofucose allows calculating lake water deuterium-excess and thus disentangling changes in the isotopic composition of precipitation and evaporative enrichment. Our deuterium-excess record reveals that the warm Bølling-Allerød and Early Holocene were characterized by more evaporative enrichment compared to the colder Younger Dryas. Site-specific hydrological conditions, seasonality, and coupling δ2H and δ18O are thus important when interpreting isotope records.

Quantitative evaluation for the sources and aging processes of organic aerosols in urban Guangzhou: Insights from a comprehensive method of dual‑carbon isotopes and macro tracers

Organic carbon aerosol (OC) is a pivotal component of PM_2.5 in the atmospheric environment, yet its emission sources and atmospheric behaviors remain poorly constrained in many regions. In this study, a comprehensive method based on the combination of dual‑carbon isotopes (¹³C and ¹⁴C) and macro tracers was employed in the PRDAIO campaign performed in the megacity of Guangzhou, China. The ¹⁴C analysis showed that 60 ± 9 % of OC during the sampling campaign was associated with non-fossil sources such as biomass burning activities and biogenic emissions. It should be noted that this non-fossil contribution in OC would significantly decrease when the air masses came from the eastern cities. Overall, we found that non-fossil secondary OC (SOC_NF) was the largest contributor (39 ± 10 %) to OC, followed by fossil secondary OC (SOC_FF: 26 ± 5 %), fossil primary OC (POC_FF: 14 ± 6 %), biomass burning OC (OC_bb: 13 ± 6 %) and cooking OC (OC_ck: 8 ± 5 %). Also, we established the dynamic variation of ¹³C as a function of aged OC and the volatile organic compounds (VOCs) oxidized OC to explore the impact of aging processes on OC. Our pilot results showed that atmospheric aging was highly sensitive to the emission sources of seed OC particles, with a higher aging degree (86 ± 4 %) when more non-fossil OC particles were transferred from the northern PRD.

Is biomass burning always a dominant contributor of fine aerosols in upper northern Thailand?

Biomass burning (BB) is an important contributor to the air pollution in Southeast Asia (SEA), but the emission sources remain great uncertainty. In this study, PM2.5 samples were collected from an urban (Chiang Mai University, CMU) and a rural (Nong Tao village, NT) site in Chiang Mai, Thailand from February to April (high BB season, HBB) and from June to September (low BB season, LBB) in 2018. Source apportionment of carbonaceous aerosols was carried out by Latin Hypercube Sampling (LHS) method incorporating the radiocarbon (14C) and organic markers (e.g., dehydrated sugars, aromatic acids, etc.). Thereby, carbonaceous aerosols were divided into the fossil-derived elemental carbon (ECf), BB-derived EC (ECbb), fossil-derived primary and secondary organic carbon (POCf, SOCf), BB-derived OC (OCbb) and the remaining OC (OCnf, other). The fractions of ECbb generally prevailed over ECf throughout the year. OCbb was the dominant contributor to total carbon with a clear seasonal trend (65.5 ± 5.8 % at CMU and 79.9 ± 7.6 % at NT in HBB, and 39.1 ± 7.9 % and 42.8 ± 4.6 % in LBB). The distribution of POCf showed a spatial difference with a higher contribution at CMU, while SOCf displayed a temporal variation with a greater fraction in LBB. OCnf, other was originated from biogenic secondary aerosols, cooking emissions and bioaerosols as resolved by the principal component analysis with multiple liner regression model. The OCnf, other contributed within a narrow range of 6.6 %-14.4 %, despite 34.9 ± 7.9 % at NT in LBB. Our results highlight the dominance of BB-derived fractions in carbonaceous aerosols in HBB, and call the attention to the higher production of SOC in LBB.

Carbon-14 release and speciation during corrosion of irradiated steel under radioactive waste disposal conditions

Carbon-14 is a key radionuclide in the safety assessment of deep geological repositories (DGR) for low- and intermediate-level radioactive waste (L/ILW). Irradiated metallic wastes generated during the decommissioning of nuclear power plants are an important source of ¹⁴C after their disposal in a DGR. The chemical form of ¹⁴C released from the irradiated metallic wastes determines the pathway of migration from the DGR into the environment. In a long-term corrosion experiment with irradiated steel simulating the hyper-alkaline, anoxic conditions of a cement-based DGR, total inorganic (TI¹⁴C²) and organic ¹⁴C contents (TO¹⁴C) in the liquid and gas phases (TG¹⁴C), as well as individual ¹⁴C-bearing carbon compounds by compound-specific radiocarbon analysis (CSRA), were quantified using accelerator mass spectrometry (AMS). The AMS-based quantification allows the determination of ¹⁴C in the pico- to femtomolar concentration range. An initial increase in TO¹⁴C was observed, which could be attributed partially to the release of ¹⁴C-bearing oxygenated carbon compounds. In the long term, TO¹⁴C and the TI¹⁴C remain constant, while TG¹⁴C increases over time according to a corrosion rate of steel of 1 nm/yr. In solution, ¹⁴C-bearing carboxylic acids (CAs) contribute ~40% to TO¹⁴C, and they are the main ¹⁴C carriers along with ¹⁴C-bearing carbonate (¹⁴CO₃^2-). The remaining fraction of TO¹⁴C (~ 60%) is likely due to the presence of as yet non-identified polymeric or colloidal organic material. In the gas phase, ¹⁴CH₄ accounts for more than 80% of the TG¹⁴C, while only trace amounts of ¹⁴CO, and other small ¹⁴C-bearing hydrocarbons have been detected. In a DGR, the release of ¹⁴C will be mainly in gaseous form and migrate via the gas pathway from the repository near field to the surrounding host rock and eventually to the environment.

Migration of iodine-129 and iodine-127 in soils

To draw the balance of anthropogenic 129I input into European soils, the concentrations of 129I and 127I in seven soils from Lower Saxony were analyzed down to a depth of 250 cm. In comparison with pre-nuclear soils and Ukrainian soils, we detected a significant anthropogenic input of 129I. Considering the different time periods for the input of 129I and 127I it was possible to assess the dynamics of sorption processes which dominate migration and accumulation. Anthropogenic 129I was successfully used as a tracer for a clarification of the migration processes of trace elements in soils.

Soil carbon loss from drained agricultural peatland after coverage with mineral soil

Drainage for agriculture has turned peatlands from a net sink to a net source of carbon (C). In order to reduce the environmental footprint of agricultural peatland drainage, and to counteract soil subsidence, mineral soil coverage is becoming an increasingly used practice in Switzerland. To explore the effect of mineral soil coverage on soil C loss and the source of CO₂ from peatland drained for agriculture, we utilized the radiocarbon signature (F¹⁴C) of soil C and emitted CO₂ in the field. The experiment, located in the Swiss Rhine Valley, was carried out on two adjacent drained organic soils, either without mineral soil cover (reference 'Ref'), or covered with mineral soil (thickness ~ 40 cm) (coverage 'Cov') 13 years ago. Drainage already commenced 130 years ago and the site was managed as meadow since the 1970ies. Drainage induced 41-75 kg C m^-2 loss, which is equivalent to annual C loss rates of 0.49-0.58 kg C m^-2 yr^-1 and 0.31-0.63 kg C m^-2 yr^-1 for Cov and Ref, respectively. Mineral soil coverage had no significant effect on the amount of heterotrophic respiration, however, at Cov, the radiocarbon signature of heterotrophic CO₂ was significantly (p<0.01) younger than at Ref, indicating that mineral soil coverage moved the source of decomposition of soil organic carbon (SOC) from a higher share of old peat towards a higher share of relatively younger material. In summary, our study lends support to the hypothesis that mineral soil coverage might reduce the decomposition of old peat underneath, and may therefore be a promising peatland management technique for the future use of drained peatland for agriculture.

Electrospray Mediated Localized and Targeted Chemotherapy in a Mouse Model of Lung Cancer

Background: An advanced stage, centrally localized invasive tumor is a major cause of sudden death in lung cancer patients. Currently, chemotherapy, radiotherapy, laser ablation, or surgical resection if possible are the available state-of-the-art treatments but none of these guarantee remedy or long-term relief and are often associated with fatal complications. Allowing localized chemotherapy, by direct and confined drug delivery only at the tumor site, could be a promising option for preoperative down staging or palliative therapy. Here we report the localized and targeted application of intra tumor delivery of chemotherapeutics using a novel device based on the principle of electrospray.

Methods: C57BL/6J mice were injected with Lewis lung carcinoma cells subcutaneously. After 15 days, the animals were anesthetized and the tumors were exposed by skin incision. Tumors were electrosprayed with 100 µg cisplatin on days 0 and 2, and tumor volumes were measured daily. Animals were sacrificed on day 7 after the first electrospray and tumors were analyzed by immunohistochemistry.

Results: In this proof-of-concept study, we report that the tumor volume was reduced by 81.2% (22.46 ± 12.14 mm³) after two electrospray mediated Cisplatin deliveries, while the control tumor growth, at the same time point, increased by 200% (514.30 ± 104.50 mm³). Moreover, tunnel and Caspase-3 positive cells were increased after Cisplatin electrospray compared to other experimental groups of animals.

Conclusion: Targeted drug delivery by electrospray is efficient in the subcutaneous mouse model of lung cancer and offers a promising opportunity for further development toward its clinical application.

Determination of ultra-low concentrations of gaseous 14C-bearing hydrocarbons produced during corrosion of irradiated steel using accelerator mass spectrometry

Compound-specific radiocarbon analysis (CSRA) was developed to identify and quantify gaseous 14C-bearing carbon compounds at the pico- to femtomolar concentration range and employed in a corrosion experiment with small specimens of irradiated steel. The approach is based on gas chromatographic separation of single 14C-bearing carbon compounds, their oxidation to 14CO2, sampling with a custom-made fraction collector and quantification by accelerator mass spectrometry (AMS). In addition to CSRA, a method allowing the quantification of the total 14C content of the gas phase was developed and tested. After validation of the two set-ups with standards, the gaseous 14C-bearing carbon compounds produced during alkaline anoxic corrosion of irradiated steel were quantified. Small hydrocarbons (HCs) like methane (14CH4) and ethane (14C2H6) were the only 14C-bearing compounds identified in the gas phase above the detection limit. 14CH4 was the main species (on average 5.4 × 10-14 mol L-1 gas) and contributed >90% to the total 14C content, whereas the concentration of 14C2H6 was much lower (7.9 × 10-16 mol L-1 gas). To our knowledge, this is the first study reporting CSRA of gaseous 14C-bearing HCs produced during anoxic corrosion of irradiated metallic radioactive waste at ultra-low concentrations.

An evaluation of source apportionment of fine OC and PM2.5 by multiple methods: APHH-Beijing campaigns as a case study

This paper reports an evaluation of multiple source apportionment methods for OC and PM_2.5.

14C Research at the Laboratory for the Analysis of Radiocarbon with AMS (LARA), University of Bern

The Laboratory for the Analysis of Radiocarbon with AMS (LARA) at the University of Bern measures the radioactive carbon isotope ¹⁴C with accelerator mass spectrometry (AMS) in different applications. Besides radiocarbon dating of environmental and archaeological samples, the LARA focuses on source apportionment of air-borne particulate matter (i.e. aerosols) as well as greenhouse gases such as carbon dioxide and methane. This approach allows the identification and quantification of fossil carbon emissions in these air components, which is relevant for measures of air-quality improvement. The LARA furthermore develops instrumental setups for and at the AMS in order to analyze ¹⁴C samples in μg-amounts with low contamination and high throughput, preferably using online-hyphenated systems.

Glacial heterogeneity in Southern Ocean carbon storage abated by fast South Indian deglacial carbon release

Past changes in ocean ¹⁴C disequilibria have been suggested to reflect the Southern Ocean control on global exogenic carbon cycling. Yet, the volumetric extent of the glacial carbon pool and the deglacial mechanisms contributing to release remineralized carbon, particularly from regions with enhanced mixing today, remain insufficiently constrained. Here, we reconstruct the deglacial ventilation history of the South Indian upwelling hotspot near Kerguelen Island, using high-resolution ¹⁴C-dating of smaller-than-conventional foraminiferal samples and multi-proxy deep-ocean oxygen estimates. We find marked regional differences in Southern Ocean overturning with distinct South Indian fingerprints on (early de-)glacial atmospheric CO₂ change. The dissipation of this heterogeneity commenced 14.6 kyr ago, signaling the onset of modern-like, strong South Indian Ocean upwelling, likely promoted by rejuvenated Atlantic overturning. Our findings highlight the South Indian Ocean’s capacity to influence atmospheric CO₂ levels and amplify the impacts of inter-hemispheric climate variability on global carbon cycling within centuries and millennia.

A Southern Ocean influences on the carbon cycle is considered a key component of deglacial changes. Here, the authors show spatial differences in glacial Southern Ocean carbon storage that dissipated rapidly 14.6 kyr ago, revealing a South Indian Ocean contribution to rapid deglacial atmospheric CO₂ increases.

High-Resolution Historical Record of Plant Protection Product Deposition Documented by Target and Nontarget Trend Analysis in a Swiss Lake under Anthropogenic Pressure

A multiproxy workflow was used to assess >60 plant protection products (PPPs) in sediment samples from a Swiss lake under heavy agricultural pressure. The results show the appearance of PPPs for the first time in the early 1960s with an overall detection of 34 PPPs and with herbicides and fungicides found in equal proportions. Paleolimnological data [e.g., chronology, hyperspectral imaging of sedimentary green pigments, and semiquantitative elemental composition (μXRF scans)] suggest that PPP concentrations and fluxes to the sediment over time are not related to land surface processes such as soil erosion or lake biogeochemistry but are attributed mainly to PPP application (inferred from sales) or regulatory measures (bans). Additional compounds with similar sources of contamination as the target PPPs captured by nontarget trend analysis (≥2000 unknown profiles) reveal significant inputs of contaminants to the lake starting in the 1970s, followed by a decrease of contamination at the beginning of the 1990s and a constant increase by ∼28% of the unknown compounds since the year 2000. An ecological risk assessment conducted on detected PPPs indicates that since the 1980s, the sediment quality is insufficient with risk quotient values displaying maximum levels in the most recent sediments (∼2010) despite bans of specific PPPs and environmental regulations.

Troubles in Tuva: Patterns of perimortem trauma in a nomadic community from Southern Siberia (second to fourth c. CE)

OBJECTIVES

Warfare is assumed to be one of the defining cultural characteristics of steppe nomads in Eastern Eurasia. For the first-centuries CE, a period of political turmoil in Northern China and Southern Siberia, relatively few data are, however, available about the degree and variability of violence in these communities. Here, we provide new data on violence among steppe nomads during the first-centuries CE by analyzing the type, anatomical distribution, and demographic distribution of perimortem trauma at Tunnug1 (Tuva, Southern Siberia-second to fourth c. CE).

MATERIALS AND METHODS

Perimortem traumas were assessed on 87 individuals representing both sexes and different age classes. The timing of the lesions was assessed based on morphological criteria, including the absence and presence of bone reactive processes and the relative plasticity of the bone at the moment of impact. The distribution by age, sex, and anatomical location of trauma was analyzed by means of logistic models, Fisher's exact tests, and 3D visualizations.

RESULTS

A total of 130 perimortem traumas, including chop marks, slice marks, penetrating lesions, and blunt traumas were identified on 22 individuals. Chop marks were mostly at the level of the skull and vertebrae and were likely caused by bladed weapons. Slice marks were found on the cervical vertebrae and cranium and may be the result of throat slitting and scalping by means of smaller bladed implements. Traumas were more frequent in males, and their presence is not correlated with age.

DISCUSSION

This study adds new data to the few available regarding violence among steppe nomadic cultures and provides new insights about the effects of political instability on the life of the people inhabiting Eastern Eurasia during the early centuries CE.

Increased uranium concentrations in ground and surface waters of the Swiss Plateau: A result of uranium accumulation and leaching in the Molasse basin and (ancient) wetlands?

Increased uranium (U) concentrations are found in certain ground and surface waters of the Swiss Plateau. Analysis of more than 100 public fountains revealed that increased ²³⁸U concentrations frequently occur close to the interface between the Lower Freshwater Molasse and the Upper Marine Molasse, cropping out in the western part of the Swiss Molasse Basin. Out of these locations, Mont Vully, situated ca. 20 km west of Berne, was studied in detail. As this hill consists of the two aforementioned stratigraphic Molasse units, it represents an ideal case study. Two springs at the northern slopes of Mont Vully exhibit the highest ²³⁸U concentrations with more than 300 mBq/L and were thus monitored for almost two years in order to screen possible seasonal variations. Further water samples were collected from spring captures, creeks and drainage pipes. The pipes drain the farmland north of Mont Vully showing ²³⁸U concentrations with more than 600 mBq/L. In order to discover the reason for the duplication in concentration, gamma dose rate measurements were accomplished on the farmland, revealing elevated dose rates of up to 160 nSv/h. These are located above ancient pathways of creeks that originated from Mont Vully. At these locations with elevated dose rates, three shallow sediment drill cores were taken and analyzed for their U content. The sediment cores can essentially be divided into three parts: (i) an upper soil with common U concentrations of about 30 Bq/kg ²³⁸U, (ii) an U-rich peat horizon with concentrations of up to 500 Bq/kg ²³⁸U, and (iii) an impermeable clay unit that acts as an aquitard with again minor ²³⁸U concentrations. Radiocarbon dating of the U-rich peat horizon reveals ages younger than 8.1 kyrs. This study suggests that a wetland was formed on top of the impermeable clay layer after the last glaciation during the Holocene. The stream waters with ²³⁸U concentrations of more than 300 mBq/L originating from Mont Vully contributed significantly to the water supply for the development of the wetland. Due to the reducing conditions that are present in wetlands, the dissolved U in the incoming streams was reduced and adsorbed onto organic matter. Accordingly, an entrapment for U was generated, persisting for at least 6 kyrs - a sufficient time to accumulate up to 500 Bq/kg. In the course of the last century, numerous wetlands in Switzerland were drained by capturing streams and installing drainage pipes to make the land suitable for agriculture. This kind of melioration was also done at the wetlands north of Mont Vully resulting in a subsequent change in redox conditions within the soil. The solubility of U depends on its oxidation state and U can be oxidized by oxygen-rich rainwater. The rainwater leached the U adsorbed on the peat yielding ²³⁸U concentrations of more than 600 mBq/L. Consequently, the duplication of ²³⁸U concentrations in the drainage water as compared to the original concentration that creeks brought into the ancient wetlands has been clarified during this study. Twenty of the analyzed public fountains in the Swiss Plateau exhibited a ²³⁸U concentration of more than 50 mBq/L. All of them could have contributed to the formation of a wetland after the last glaciation, which leads to the assumption that the situation at Mont Vully is not a singularity in the Swiss Plateau.

Analysis of 14C-bearing compounds released by the corrosion of irradiated steel using accelerator mass spectrometry

The combination of ion chromatography (IC) with accelerator mass spectrometry (AMS) was developed to determine the speciation of 14C-(radiocarbon) bearing organic compounds in the femto to pico molar concentration range. The development of this compound-specific radiocarbon analysis (CSRA) of carboxylic acids is reported and the application of the method on a leaching solution from neutron-irradiated steel is demonstrated. The background and the dynamic range of the AMS-based method were quantified. On using 14C-labelled standards, the measurements demonstrate the repeatability of the analytical method and the reproducible recovery of the main target carboxylic acids (i.e., acetate, formate, malonate, and oxalate). The detection limit was determined to be in the mid fmol 14C per L level while the dynamic range of the analytical method covers three orders of magnitude from the low fmol to the mid pmol 14C per L level. Cross contamination was found to be negligible during IC fractionation and was accounted for during eluate processing and 14C detection by AMS. The 14C-bearing carboxylates released from an irradiated steel nut into an alkaline leaching solution were analysed using the CSRA-based analytical method with the aim to check the applicability of the approach and develop appropriate sample preparation. The concentrations of 14C-bearing formate and acetate, the main organic corrosion products, were at a low pmol 14C per L level for convenient dimensions of the alkaline leaching experiment which demonstrates that compound-specific 14C AMS is an extremely sensitive analytical method for analysing 14C-bearing compounds. The content of total organic 14C in solution (TO14C) determined by the direct measurement of an aliquot of the leaching solution agrees well with the sum of the 14C concentrations of the individual carboxylates within the uncertainty of the data. Furthermore, the TO14C content is in good agreement with the calculated value using the corrosion rate determined from the 60Co release and the 14C inventory of the irradiated steel specimen.

High Contribution of Nonfossil Sources to Submicrometer Organic Aerosols in Beijing, China

Source apportionment of organic carbon (OC) and elemental carbon (EC) from PM₁ (particulate matter with a diameter equal to or smaller than 1 μm) in Beijing, China was carried out using radiocarbon (¹⁴C) measurement. Despite a dominant fossil-fuel contribution to EC due to large emissions from traffic and coal combustion, nonfossil sources are dominant contributors of OC in Beijing throughout the year except during the winter. Primary emission was the most important contributor to fossil-fuel derived OC for all seasons. A clear seasonal trend was found for biomass-burning contribution to OC with the highest in autumn and spring, followed by winter and summer. ¹⁴C results were also integrated with those from positive matrix factorization (PMF) of organic aerosols from aerosol mass spectrometer (AMS) measurements during winter and spring. The results suggest that the fossil-derived primary OC was dominated by coal combustion emissions whereas secondary OC was mostly from fossil-fuel emissions. Taken together with previous ¹⁴C studies in Asia, Europe and USA, a ubiquity and dominance of nonfossil contribution to OC aerosols is identified not only in rural/background/remote regions but also in urban regions, which may be explained by cooking contributions, regional transportation or local emissions of seasonal-dependent biomass burning emission. In addition, biogenic and biomass burning derived SOA may be further enhanced by unresolved atmospheric processes.

Land Use Affects Carbon Sources to the Pelagic Food Web in a Small Boreal Lake

Small humic forest lakes often have high contributions of methane-derived carbon in their food webs but little is known about the temporal stability of this carbon pathway and how it responds to environmental changes on longer time scales. We reconstructed past variations in the contribution of methanogenic carbon in the pelagic food web of a small boreal lake in Finland by analyzing the stable carbon isotopic composition (δ13C values) of chitinous fossils of planktivorous invertebrates in sediments from the lake. The δ13C values of zooplankton remains show several marked shifts (approx. 10 ‰), consistent with changes in the proportional contribution of carbon from methane-oxidizing bacteria in zooplankton diets. The results indicate that the lake only recently (1950s) obtained its present state with a high contribution of methanogenic carbon to the pelagic food web. A comparison with historical and palaeobotanical evidence indicates that this most recent shift coincided with agricultural land-use changes and forestation of the lake catchment and implies that earlier shifts may also have been related to changes in forest and land use. Our study demonstrates the sensitivity of the carbon cycle in small forest lakes to external forcing and that the effects of past changes in local land use on lacustrine carbon cycling have to be taken into account when defining environmental and ecological reference conditions in boreal headwater lakes.

Fossil and Nonfossil Sources of Organic and Elemental Carbon Aerosols in the Outflow from Northeast China

Source quantification of carbonaceous aerosols in the Chinese outflow regions still remains uncertain despite their high mass concentrations. Here, we unambiguously quantified fossil and nonfossil contributions to elemental carbon (EC) and organic carbon (OC) of total suspended particles (TSP) from a regional receptor site in the outflow of Northeast China using radiocarbon measurement. OC and EC concentrations were lower in summer, representing mainly marine air, than in other seasons, when air masses mostly traveled over continental regions in Mongolia and northeast China. The annual-mean contribution from fossil-fuel combustion to EC was 76 ± 11% (0.1-1.3 μg m(-3)). The remaining 24 ± 11% (0.03-0.42 μg m(-3)) was attributed to biomass burning, with slightly higher contribution in the cold period (∼31%) compared to the warm period (∼21%) because of enhanced emissions from regional biomass combustion sources in China. OC was generally dominated by nonfossil sources, with an annual average of 66 ± 11% (0.5-2.8 μg m(-3)), approximately half of which was apportioned to primary biomass-burning sources (34 ± 6%). In winter, OC almost equally originated from primary OC (POC) emissions and secondary OC (SOC) formation from fossil fuel and biomass-burning sources. In contrast, summertime OC was dominated by primary biogenic emissions as well as secondary production from biogenic and biomass-burning sources, but fossil-derived SOC was the smallest contributor. Distinction of POC and SOC was performed using primary POC-to-EC emission ratios separated for fossil and nonfossil emissions.

Secondary organic aerosol origin in an urban environment: influence of biogenic and fuel combustion precursors

Source contributions of organic aerosol (OA) are still not fully understood, especially in terms of quantitative distinction between secondary OA formed from anthropogenic precursors vs. that formed from natural precursors. In order to investigate the OA origin, a field campaign was carried out in Barcelona in summer 2013, including two periods characterized by low and high traffic conditions. Volatile organic compound (VOC) concentrations were higher during the second period, especially aromatic hydrocarbons related to traffic emissions, which showed a marked daily cycle peaking during traffic rush hours, similarly to black carbon (BC) concentrations. Biogenic VOC (BVOC) concentrations showed only minor changes from the low to the high traffic period, and their intra-day variability was related to temperature and solar radiation cycles, although a decrease was observed for monoterpenes during the day. The organic carbon (OC) concentrations increased from the first to the second period, and the fraction of non-fossil OC as determined by ¹⁴C analysis increased from 43% to 54% of the total OC. The combination of ¹⁴C analysis and Aerosol Chemical Speciation Monitor (ACSM) OA source apportionment showed that the fossil OC was mainly secondary (>70%) except for the last sample, when the fossil secondary OC only represented 51% of the total fossil OC. The fraction of non-fossil secondary OC increased from 37% of total secondary OC for the first sample to 60% for the last sample. This enhanced formation of non-fossil secondary OA (SOA) could be attributed to the reaction of BVOC precursors with NO_x emitted from road traffic (or from its nocturnal derivative nitrate that enhances night-time semi-volatile oxygenated OA (SV-OOA)), since NO₂ concentrations increased from 19 to 42 μg m⁻³ from the first to the last sample.

The effect of brain size evolution on feeding propensity, digestive efficiency, and juvenile growth

One key hypothesis in the study of brain size evolution is the expensive tissue hypothesis; the idea that increased investment into the brain should be compensated by decreased investment into other costly organs, for instance the gut. Although the hypothesis is supported by both comparative and experimental evidence, little is known about the potential changes in energetic requirements or digestive traits following such evolutionary shifts in brain and gut size. Organisms may meet the greater metabolic requirements of larger brains despite smaller guts via increased food intake or better digestion. But increased investment in the brain may also hamper somatic growth. To test these hypotheses we here used guppy (Poecilia reticulata) brain size selection lines with a pronounced negative association between brain and gut size and investigated feeding propensity, digestive efficiency (DE), and juvenile growth rate. We did not find any difference in feeding propensity or DE between large- and small-brained individuals. Instead, we found that large-brained females had slower growth during the first 10 weeks after birth. Our study provides experimental support that investment into larger brains at the expense of gut tissue carries costs that are not necessarily compensated by a more efficient digestive system.

Enhanced light absorption by mixed source black and brown carbon particles in UK winter

Black carbon (BC) and light-absorbing organic carbon (brown carbon, BrC) play key roles in warming the atmosphere, but the magnitude of their effects remains highly uncertain. Theoretical modelling and laboratory experiments demonstrate that coatings on BC can enhance BC's light absorption, therefore many climate models simply assume enhanced BC absorption by a factor of ∼1.5. However, recent field observations show negligible absorption enhancement, implying models may overestimate BC's warming. Here we report direct evidence of substantial field-measured BC absorption enhancement, with the magnitude strongly depending on BC coating amount. Increases in BC coating result from a combination of changing sources and photochemical aging processes. When the influence of BrC is accounted for, observationally constrained model calculations of the BC absorption enhancement can be reconciled with the observations. We conclude that the influence of coatings on BC absorption should be treated as a source and regionally specific parameter in climate models.

Source Apportionment of Elemental Carbon in Beijing, China: Insights from Radiocarbon and Organic Marker Measurements

Elemental carbon (EC) or black carbon (BC) in the atmosphere has a strong influence on both climate and human health. In this study, radiocarbon ((14)C) based source apportionment is used to distinguish between fossil fuel and biomass burning sources of EC isolated from aerosol filter samples collected in Beijing from June 2010 to May 2011. The (14)C results demonstrate that EC is consistently dominated by fossil-fuel combustion throughout the whole year with a mean contribution of 79% ± 6% (ranging from 70% to 91%), though EC has a higher mean and peak concentrations in the cold season. The seasonal molecular pattern of hopanes (i.e., a class of organic markers mainly emitted during the combustion of different fossil fuels) indicates that traffic-related emissions are the most important fossil source in the warm period and coal combustion emissions are significantly increased in the cold season. By combining (14)C based source apportionment results and picene (i.e., an organic marker for coal emissions) concentrations, relative contributions from coal (mainly from residential bituminous coal) and vehicle to EC in the cold period were estimated as 25 ± 4% and 50 ± 7%, respectively, whereas the coal combustion contribution was negligible or very small in the warm period.

Source apportionment using radiocarbon and organic tracers for PM2.5 carbonaceous aerosols in Guangzhou, South China: contrasting local- and regional-scale haze events

We conducted a source apportionment and investigated the atmospheric behavior of carbonaceous aerosols during hazy and normal days using radiocarbon ((14)C) and biomass burning/secondary organic aerosol (SOA) tracers during winter in Guangzhou, China. Haze episodes were formed either abruptly by local emissions or through the accumulation of particles transported from other areas. The average contributions of fossil carbon to elemental carbon (EC), water-insoluble organic carbon, and water-soluble organic carbon were 71 ± 10%, 40 ± 6% and 33 ± 3%, respectively. High contributions of fossil carbon to EC (80-90%) were observed for haze samples that were substantially impacted by local emissions, as were the highest (lowest) ratios for NO3(-)/SO4(2-) (OC/EC), which indicates that these particles mainly came from local vehicle exhaust. Low contributions of fossil carbon to EC (60-70%) were found for haze particles impacted by regional transport. Secondary organic carbon (SOC) calculated using SOA tracers accounts for only ∼ 20% of the SOC estimated by (14)C, which is probably because some important volatile organic carbons are not taken into account in the SOA tracer calculation method and because of the large discrepancy in ambient conditions between the atmosphere and smog chambers. A total of 33 ± 11% of the SOC was of fossil origin, a portion of which could be influenced by humidity.

High secondary aerosol contribution to particulate pollution during haze events in China

Rapid industrialization and urbanization in developing countries has led to an increase in air pollution, along a similar trajectory to that previously experienced by the developed nations. In China, particulate pollution is a serious environmental problem that is influencing air quality, regional and global climates, and human health. In response to the extremely severe and persistent haze pollution experienced by about 800 million people during the first quarter of 2013 (refs 4, 5), the Chinese State Council announced its aim to reduce concentrations of PM2.5 (particulate matter with an aerodynamic diameter less than 2.5 micrometres) by up to 25 per cent relative to 2012 levels by 2017 (ref. 6). Such efforts however require elucidation of the factors governing the abundance and composition of PM2.5, which remain poorly constrained in China. Here we combine a comprehensive set of novel and state-of-the-art offline analytical approaches and statistical techniques to investigate the chemical nature and sources of particulate matter at urban locations in Beijing, Shanghai, Guangzhou and Xi'an during January 2013. We find that the severe haze pollution event was driven to a large extent by secondary aerosol formation, which contributed 30-77 per cent and 44-71 per cent (average for all four cities) of PM2.5 and of organic aerosol, respectively. On average, the contribution of secondary organic aerosol (SOA) and secondary inorganic aerosol (SIA) are found to be of similar importance (SOA/SIA ratios range from 0.6 to 1.4). Our results suggest that, in addition to mitigating primary particulate emissions, reducing the emissions of secondary aerosol precursors from, for example, fossil fuel combustion and biomass burning is likely to be important for controlling China's PM2.5 levels and for reducing the environmental, economic and health impacts resulting from particulate pollution.

Developmental plasticity of growth and digestive efficiency in dependence of early-life food availability

Nutrition is a potent mediator of developmental plasticity. If food is scarce, developing organisms may invest into growth to outgrow size-dependent mortality (short-term benefit) and/or into an efficient digestion system (long-term benefit). We investigated this potential trade-off, by determining the influence of food availability on juvenile body and organ growth, and on adult digestive efficiency in the cichlid fish Simochromis pleurospilus. We reared two groups of fish at constant high or low food rations, and we switched four other groups between these two rations at an early and late juvenile period. We measured juvenile growth and organ sizes at different developmental stages and determined adult digestive efficiency. Fish kept at constant, high rations grew considerably faster than low-food fish. Nevertheless, S. pleurospilus partly buffered the negative effects of low food availability by developing heavier digestive organs, and they were therefore more efficient in digesting their food as adults. Results of fish exposed to a ration switch during either the early or late juvenile period suggest (i) that the ability to show compensatory growth after early exposure to low food availability persists during the juvenile period, (ii) that digestive efficiency is influenced by varying juvenile food availability during the late juvenile phase and (iii) that the efficiency of the adult digestive system is correlated with the growth rate during a narrow time window of juvenile period.

Radiocarbon-based source apportionment of carbonaceous aerosols at a regional background site on Hainan Island, South China

To assign fossil and nonfossil contributions to carbonaceous particles, radiocarbon ((14)C) measurements were performed on organic carbon (OC), elemental carbon (EC), and water-insoluble OC (WINSOC) of aerosol samples from a regional background site in South China under different seasonal conditions. The average contributions of fossil sources to EC, OC and WINSOC were 38 ± 11%, 19 ± 10%, and 17 ± 10%, respectively, indicating generally a dominance of nonfossil emissions. A higher contribution from fossil sources to EC (∼51%) and OC (∼30%) was observed for air-masses transported from Southeast China in fall, associated with large fossil-fuel combustion and vehicle emissions in highly urbanized regions of China. In contrast, an increase of the nonfossil contribution by 5-10% was observed during the periods with enhanced open biomass-burning activities in Southeast Asia or Southeast China. A modified EC tracer method was used to estimate the secondary organic carbon from fossil emissions by determining (14)C-derived fossil WINSOC and fossil EC. This approach indicates a dominating secondary component (70 ± 7%) of fossil OC. Furthermore, contributions of biogenic and biomass-burning emissions to contemporary OC were estimated to be 56 ± 16% and 44 ± 14%, respectively.

Fossil and biogenic CO₂ from waste incineration based on a yearlong radiocarbon study

We describe the first long-term implementation of the radiocarbon (¹⁴C) method to study the share of biogenic (%Bio C) and fossil (%Fos C) carbon in combustion CO₂. At five Swiss incinerators, a total of 24 three-week measurement campaigns were performed over 1 year. Temporally averaged bag samples were analyzed for ¹⁴CO₂ by accelerator mass spectrometry. Significant differences between the plants in the share of fossil CO₂ were observed, with annual mean values from 43.4 ± 3.9% to 54.5 ± 3.1%. Variations can be explained by the waste composition of the respective plant. Based on our dataset, an average value of 48 ± 4%Fos C was determined for waste incineration in Switzerland. No clear annual trend in %Fos C was observed for four of the monitored incinerators, while one incinerator showed considerable variations, which are likely due to the separation and temporary storage of bulky goods.

On the origin of129I in rain water near Zürich

129I concentrations in precipitation at Dübendorf/Zürich, Switzerland, have been determined with monthly resolution for almost three years in the mid 1990s. The results confirm that annual mean129I concentrations in precipitation in central Europe have remained about constant since the late 1980s. Liquid and gaseous emissions from the nuclear fuel reprocessing plants at Sellafield and La Hague are discussed as the only possible sources of129I in precipitation in central Europe. Based on an upper limit estimate for iodine transferred from the sea to the atmosphere, the gaseous discharges constitute the potentially bigger129I reservoir for precipitation. Moreover, the time dependence of the annual gaseous129I releases from Sellafield and La Hague correlates much better with the129I concentrations in precipitation in central Europe since the late 1980s than does the time dependence of the liquid emissions from these sites. At monthly resolution, the129I concentrations in the precipitation samples close to Zürich exhibit a large variability. A meteorological transport analysis was carried out for four selected months with particularly low or high observed129I concentrations. It was found that meteorological transport alone, based upon assimilated wind fields and observed precipitation values, can not directly account for the large month-to-month variability.

Determination of biogenic and fossil CO(2) emitted by waste incineration based on (14)CO(2) and mass balances

A field application of the radiocarbon ((14)C) method was developed to determine the ratio of biogenic vs. fossil CO(2) emissions from waste-to-energy plants (WTE). This methodology can be used to assign the Kyoto relevant share of fossil CO(2) emissions, which is highly relevant for emission budgets and emission trading. Furthermore, heat and electricity produced by waste incinerators might be labelled depending on the fossil or biogenic nature of the primary energy source. The method development includes representative on-site CO(2) absorption and subsequent release in the laboratory. Furthermore, a reference value for the (14)C content of pure biogenic waste (f(M,bio)) was determined as 1.130+/-0.038. Gas samples for (14)CO(2) analysis were taken at three WTEs during one month each. Results were compared to an alternative approach based on mass and energy balances. Both methods were in excellent agreement and indicated a fraction of biogenic CO(2) slightly above 50%.

Using aerosol light absorption measurements for the quantitative determination of wood burning and traffic emission contributions to particulate matter

A source apportionment study was performed for particulate matter in the small village of Roveredo, Switzerland, where more than 70% of the households use wood burning for heating purposes. A two-lane trans-Alpine highway passes through the village and contributes to the total aerosol burden in the area. The village is located in a steep Alpine valley characterized by strong and persistent temperature inversions during winter, especially from December to February. During two winter and one early spring campaigns, a seven-wavelength aethalometer, high volume (HIVOL) samplers, an Aerodyne quadrupole aerosol mass spectrometer (AMS), an optical particle counter (OPC), and a Sunset Laboratory OCEC analyzer were deployed to study the contribution of wood burning and traffic aerosols to particulate matter. A linear regression model of the carbonaceous particulate mass in the submicrometer size range CM(PM1) as a function of aerosol light absorption properties measured by the aethalometer is introduced to estimate the particulate mass from wood burning and traffic (PM(wb), PM(traffic)). This model was calibrated with analyses from the 14C method using HIVOL filter measurements. These results indicate that light absorption exponents of 1.1 for traffic and 1.8-1.9 for wood burning calculated from the light absorption at 470 and 950 nanometers should be used to obtain agreement of the two methods regarding the relative wood burning and traffic emission contributions to CM(PM1) and also to black carbon. The resulting PM(wb) and PM(traffic) values explain 86% of the variance of the CM(PM1) and contribute, on average, 88 and 12% to CM(PM1), respectively. The black carbon is estimated to be 51% due to wood burning and 49% due to traffic emissions. The average organic carbon/total carbon (OC/TC) values were estimated to be 0.52 for traffic and 0.88 for wood burning particulate emissions.

Source attribution of submicron organic aerosols during wintertime inversions by advanced factor analysis of aerosol mass spectra

Real-time measurements of submicrometer aerosol were performed using an Aerodyne aerosol mass spectrometer (AMS) during three weeks at an urban background site in Zurich (Switzerland) in January 2006. A hybrid receptor model which incorporates a priori known source composition was applied to the AMS highly time-resolved organic aerosol mass spectra. Three sources and components of submicrometer organic aerosols were identified: the major component was oxygenated organic aerosol (OOA), mostly representing secondary organic aerosol and accounting on average for 52-57% of the particulate organic mass. Radiocarbon (14C) measurements of organic carbon (OC) indicated that approximately 31 and approximately 69% of OOA originated from fossil and nonfossil sources, respectively. OOA estimates were strongly correlated with measured particulate ammonium. Particles from wood combustion (35-40%) and 3-13% traffic-related hydrocarbon-like organic aerosol (HOA) accounted for the other half of measured organic matter (OM). Emission ratios of modeled HOA to measured nitrogen oxides (NOx) and OM from wood burning to levoglucosan from filter analyses were found to be consistent with literature values.

Identification of the mass spectral signature of organic aerosols from wood burning emissions

Throughout the winter months, the village of Roveredo, Switzerland, frequently experiences strong temperature inversions that contribute to elevated levels of particulate matter. Wood is used as fuel for 75% of the domestic heating installations in Roveredo, which makes it a suitable location to study wood burning emissions in the atmosphere in winter. An Aerodyne quadrupole aerosol mass spectrometer (Q-AMS) was used to characterize the composition of the submicrometer, non-refractory aerosol particles at this location during two field campaigns in March and December 2005. Wood burning was found to be a major source of aerosols at this location in winter. Organics dominated the composition of the aerosols from this source, contributing up to 85% of the total AMS measured mass during the afternoon and evening hours. Carbonaceous particle analysis showed that organic carbon composed up to 86% of the total carbon mass collected at evening times. Results from 14C isotope determination revealed that up to 94% of the organic mass came from non-fossil sources, which can be attributed mostlyto wood burning. The unique combination of off-line 14C isotope analysis and on-line aerosol mass spectrometry was used to identify periods during which organic mass was mainly from wood burning emissions and allowed for the identification of the AMS spectral signature of this source in the atmosphere. The identified ambient signature of wood burning was found to be very similar to the mass spectral signature obtained during the burning of chestnut wood samples in a small stove and also to the spectrum of levoglucosan. Particles from wood burning appeared to be composed of highly oxygenated organic compounds, and mass fragments 60, 73, and 137 have been suggested as marker fragments for wood burning aerosols. Mass fragment 44, which is used as a marker for oxygenated organic aerosols (OOA), contributed about 5% to the total organic signal from primary wood burning sources. The ratio of the organic mass emitted from wood burning to m/z 60 in Roveredo is 36. This ratio may be used to provide an estimate of the organic aerosol mass emitted from wood burning in other locations.

Determination of stable carbon isotopes of organic acids and carbonaceous aerosols in the atmosphere

A wet oxidation method for the compound-specific determination of stable carbon isotopes (delta(13)C) of organic acids in the gas and aerosol phase, as well as of water-soluble organic carbon (WSOC), is presented. Sampling of the organic acids was done using a wet effluent diffusion denuder/aerosol collector (WEDD/AC) coupled to an ion chromatography (IC) system. The method allows for compound-specific stable carbon isotope analysis by collecting different fractions of organic acids at the end of the IC system using a fraction collector. delta(13)C analyses of organic acids were conducted by oxidizing the organic acids with sodium persulfate at a temperature of 100 degrees C and determining the delta(13)C value of the resulting carbon dioxide (CO(2)) with an isotope ratio mass spectrometer. In addition, analysis of delta(13)C of the WSOC was performed for particulate carbon collected on aerosol filters. The WSOC was extracted from the filters using ultrapure water (MQ water), and the dissolved organic carbon was oxidized to CO(2) using the oxidation method. The wet oxidation method has an accuracy of 0.5 per thousand with a precision of +/-0.4 per thousand and provides a quantitative result for organic carbon with a detection limit of 150 ng of carbon.

Iodine-129 in soils from Northern Ukraine and the retrospective dosimetry of the iodine-131 exposure after the Chernobyl accident

Forty-eight soil profiles down to a depth of 40 cm were taken in Russia and Ukraine in 1995 and 1997, respectively, in order to investigate the feasibility of retrospective dosimetry of the 131I exposure after the Chernobyl accident via the long-lived 129I. The sampling sites covered areas almost not affected by fallout from the Chernobyl accident such as Moscow/Russia and the Zhitomir district in Ukraine as well as the highly contaminated Korosten and Narodici districts in Ukraine. 129I was analyzed by radiochemical neutron activation analysis (RNAA) and accelerator mass spectrometry (AMS). 127I was measured for some profiles by RNAA or ion chromatography (IC). The results for 127I demonstrated large differences in the capabilities of the soils to store iodine over long time spans. The depth profiles of 129I and of 137Cs showed large differences in the migration behavior between the two nuclides but also for each nuclide among the different sampling sites. Though it cannot be quantified how much 129I and 137Cs was lost out of the soil columns into deeper depths, the inventories in the columns were taken as proxies for the total inventories. For 129I, these inventories were at least three orders of magnitude higher than a pre-nuclear value of 0.084+/-0.017 mBq m(-2) derived from a soil profile taken in 1939 in Lutovinovo/Russia. From the samples from Moscow and Zhitomir, a pre-Chernobyl 129I inventory of (44+/-24) mBq m(-2) was determined, limiting the feasibility of 129I retrospective dosimetry to areas where the 129I inventories exceed 100 mBq m(-2). Higher average 129I inventories in the Korosten and Narodici districts of 130 and 848 mBq m(-2), respectively, allowed determination of the 129I fallout due to the Chernobyl accident. Based on the total 129I inventories and on literature data for the atomic ratio of 129I/131I=13.6+/-2.8 for the Chernobyl emissions and on aggregated dose coefficients for 131I, the thyroid exposure due to 131I after the Chernobyl accident was estimated for the inhabitants of four villages in the Korosten and of three villages in the Narodici districts. The limitations and uncertainties of the 129I retrospective dosimetry are discussed.

Relative influence of 129I sources in a sediment core from the Kattegat area

The depth profiles of the (129)I concentration and the (129)I/(127)I ratio in a surface sediment core from the Kattegat area have been analyzed in order to obtain information about the different sources of (129)I in that core. Therefore, a mathematical model that relates the measured values to the available emission data from the nuclear fuel reprocessing plants and nuclear weapons tests has been applied. Results show that the reprocessing plants at La Hague and Sellafield are the main sources of (129)I in the sediment. Results about the transfer from the release points at the reprocessing plants to the sampling zone agree with other literature data. The model calculates quite fast the sedimentation of (129)I in the sampling place, probably attached to organic matter. Finally, an estimation of approximately 89 kg of (129)I released by Sellafield between 1952 and 1968 has been obtained from the model.