Monte-Carlo prediction of changes in areas of west Cumbria requiring restrictions on sheep following the Chernobyl accident

Following the 1986 Chernobyl accident radiocaesium levels in sheep meat in some upland areas of the United Kingdom were above the national intervention limit. West Cumbria was one of these areas and restrictions are currently still in place. In addition to deposition from the Chernobyl accident, Cumbria has been subject to radiocaesium deposition from atmospheric nuclear weapons tests, the 1957 Windscale accident and routine releases from the Sellafield nuclear reprocessing plant. A Monte-Carlo approach has been used to try to predict areas in west Cumbria where radiocaesium activity concentrations in lamb meat would require the imposition of restrictions at different times after the Chernobyl accident. The approach models the transfer of radiocaesium from soil to vegetation, based upon soil organic matter, and from vegetation to lamb meat. Spatial inputs are soil organic matter and total post-Chernobyl (137)Cs and (134)Cs deposition; a ratio of Chernobyl (137)Cs to (134)Cs deposition has been used to differentiate Chernobyl and pre-Chernobyl (137)Cs deposition. Comparisons of predicted radiocaesium transfer from soil-vegetation and the spatial variation in lamb (137)Cs activity concentrations are good and predicted restricted areas with time after Chernobyl compare well to the restricted areas set by UK government. We predict that restrictions may be required until 2024 and that in some areas the contribution of pre-Chernobyl (137)Cs to predicted lamb radiocaesium activity concentrations is significant, such that restrictions may only have been required until 1994 as a consequence of Chernobyl radiocaesium deposition alone. This work represents a novel implementation of a spatial radioecological model using a Monte-Carlo approach.     

Body concentration of caesium-137 in patients from Western Isles of Scotland.

OBJECTIVES--To compare caesium-137 concentrations in patients from the Western Isles Health Board, Glasgow area, and other parts of the Scottish mainland, and to investigate the source of 137Cs in patients from the Western Isles. DESIGN--Study of hypertensive patients having electrolyte concentrations measured, including 137Cs. Interview by questionnaire of island subjects about intake of foods likely to contain radiocaesium and the source of these foods. Measurement of 137Cs and 134Cs in food, urine, and vegetation. SETTING--Scottish mainland and Western Isles, 1979-86. All measurements before Chernobyl nuclear accident. PATIENTS--413 consecutive patients referred to the blood pressure unit for investigation of hypertension. 60 from the Western Isles, including 44 from North Uist; 32 from North Uist participated in the dietary analysis. MAIN OUTCOME MEASURES--Concentration of radiocaesium in the body, urine, food, and vegetation. Islanders'' consumption of local produce. RESULTS--Patients from the Western Isles had five times higher body concentrations of 137Cs (median 2.54 (interquartile range 1.25-3.73)) Bq/gK) than did patients from around Glasgow (0.47 (0.26-0.66) Bq/gK) and other parts of the Scottish mainland (0.42 (0.24-0.71) Bq/gK). Islanders often consumed local milk and mutton, but ate local fish rarely. 137Cs and 134Cs were present in coastal (21.6 Bq/kg 137Cs, 0.25 Bq/kg 134Cs) and moorland (135.9, 0.65 Bq/kg) grasses and in islanders'' urine (2.01, 0.013 Bq/l). Lower concentrations (0.336, 0.004 Bq/l), were found in the urine of Glasgow controls (p less than 0.001 for both isotopes). CONCLUSIONS--Islanders have excess body 137Cs concentrations, most of which probably comes from local milk and lamb. The radioactivity is not above the recommended safety limit. The presence of 134Cs suggests that nuclear reprocessing is the source of some of the radiocaesium.     

Investigations on the radiocaesium contamination of wild boar (Sus scrofa) meat in Rhineland-Palatinate: a stomach content analysis

To substantiate the pathways of radiocaesium contamination in wild boars in parts of Rhineland-Palatinate, we analysed radiocaesium-activityconcentration of 2,433 wild boars shot in an area covering 45,400 ha in the western part of the Palatinate Forest between January 2001 and February 2003. Also, for a fraction of 689 animals shot between May 2002 and February 2003, we collected their stomachs for the examination of content and Cs-activity concentration. Wild boar meat contamination followed a seasonal curve with maximum proportions exceeding accepted levels in the summer (21–26%) and minimum levels in winter (1–9.3%) indicating a higher consumption of a contaminating source during the vegetation period. The autumn decline is obviously attributed to the extensive consumption of low-contaminated beech nuts. An exact analysis of food composition in 18 stomachs with maximum Cs-activity concentrations [345–1,749 Bq/kg (fresh matter: fm)] and 18 with low Cs-activity concentrations (20–199 Bq/kg) was carried out in the summer of 2002. Deer truffles (Elaphomyces granulatus) were found in significantly higher proportions in stomachs with maximum contamination levels than in stomachs with lowcontamination levels. This fungus was found in the Palatinate Forest, by a trained dog, in average densities of 1 truffel/20 m² primarily in spruce stands, showing an average Cs-concentration of 6,030 Bq/kg (fm). On the basis of our findings we stress the hypothesis that deer truffles function as a main Cs-source for the wild boar in Rhineland-Palatinate.     

Fluvial transport and redistribution of Chernobyl fallout radionuclides

Fallout of Chernobyl-derived radionuclides over the UK evidenced marked spatial variation. Relatively high levels were recorded in central Wales, but they declined rapidly to the east and southeast. As a result, the headwaters of the River Severn received substantial inputs of fallout, whereas only low levels were recorded over the middle and lower reaches of its drainage basin. This situation afforded a valuable opportunity to investigate the sediment-associated transport of Chernobyl-derived radiocaesium through the 10 000 km² drainage basin and its redistribution by fluvial processes.Information on the fallout inputs of radiocaesium has been obtained from the sampling of soil inventories across the basin. Measurements of the radiocaesium content of suspended sediment have been made at several sites on the main river over a period extending from before the Chernobyl disaster through to 1988. Concentrations of caesium-137 in the suspended sediment increased by two orders of magnitude immediately after the accident up to 1450 mBq g ^–1, declined rapidly subsequently, but remained almost an order of magnitude greater than the pre-Chernobyl levels throughout the remainder of the period (1986–1988). Downstream redistribution of radiocaesium has occurred as a result of deposition of sediment-associated radiocaesium in channel and floodplain sinks. It is estimated that 0.6% of the total fallout input of Chernobyl-derived caesium-134 has been transported out of the basin during the period 1986–1990. Estimates of channel and floodplain storage of sediment-associated caesium-134 at the time of sampling in 1988 and 1989 account for 0.01% and 0.2% of the total fallout input to the basin respectively.     

Root uptake and translocation of radiocaesium from agricultural soils by various plant species

Plant uptake of radiocaesium from soil is an important pathway for the entry of this pollutant into the human food chain and so contributes to any assessment of the radiation dose following contamination. Large differences in soil–plant transfer factors have been reported for plant species grown on the same soils. Few studies have attempted to distinguish between differences in root uptake and root-to-shoot translocation. We have investigated the root uptake of radiocaesium from artificially contaminated soils and the subsequent translocation to shoots for various plant species grown on three agricultural soils. The effects of short contact times and potassium starvation or enrichment have been studied. The Cs adsorption properties of rhizosphere soils have been compared with those of the initial soils. The proportion of activity removed from soil is largely soil dependent. Root uptake properties have less effect, but appear to be species determined, and not influenced by soil properties. Differences in soil-to-shoot transfer factor arise from species-dependent differences in root-to-shoot translocation. Root-to-shoot activity ratios are not soil dependent. There was little effect of soil potassium status. Root action slightly enhanced Cs adsorption on one soil, probably due to mineral weathering associated with the release of nonexchangeable potassium.     

Radiocaesium in lynx in relation to ground deposition and diet

The european lynx (Lynx lynx) might be expected to have a high intake of radiocaesium in the parts of Sweden where the main prey of the lynx, namely reindeer and roe deer have high activity concentrations of radiocaesium because of high ground deposition. We have measured ¹³⁷Cs in muscle samples from 733 lynx during 1996–2003. The aim was to quantify the extent to which radiocaesium is transferred from fallout deposition to lynx, to test whether the transfer was higher in areas where there are reindeer present, to see if there was any decline in radiocaesium over time, and to calculate the radiation dose to lynx. Most samples were collected in central and northern Sweden during January–April. Activity concentrations in lynx varied from 13 Bq kg^–1 to about 15 kBq kg^–1 fresh weight, with the highest value corresponding to a radiation dose at 18 mGy/year. Aggregated transfer coefficients (Tag), calculated by dividing the ¹³⁷Cs activity concentration in lynx muscle by the average ground deposition (total from Chernobyl and nuclear weapon tests) within a 50 km radius around the location of the lynx, varied from 0.004 to 1.3 m² kg^–1 and were significantly higher within the reindeer herding area than outside. The concentration ratio (CR) for lynx/reindeer was 2.6 on average, whilst the average for lynx/roe deer outside the reindeer herding area was lower at 1.3. Based on these results, a CR of around 2 could be considered representative for the general ratio between predator and prey. A long-term decline of radiocaesium in prey species was reflected in lynx, with an effective half-life of 7 years from 1996 to 2003. The study shows that the accumulation of radiocaesium in predators, especially predators of reindeer, makes them more vulnerable to high radiocaesium deposition than most other wild species.     

The record of deposition of radionuclides in the sediments of Ponsonby Tarn,Cumbria

A study has been made of the radionuclide content of sediments from Ponsonby Tarn in Cumbria to examine the pattern of deposition of radiocaesium and actinides upon the catchment. Sediment cores obtained from the tarn in 1986 were dated by core correlation and compared with results obtained from a previous study in 1980 (Eakins & Cambray, 1985).Sediments from the tarn contained actinides derived mainly from discharges to atmosphere. The 1986 cores contain greater quantities of weapons fallout derived caesium than may be accounted for by direct atmospheric input but less attributable to the Chernobyl accident than expected. Diatom analysis together with increased sediment accumulation rates post 1980 suggest that complex patterns of sedimentation have contributed to the changes evident in the sediment.     

Measles on the edge: coastal heterogeneities and infection dynamics

Mathematical models can help elucidate the spatio-temporal dynamics of epidemics as well as the impact of control measures. The gravity model for directly transmitted diseases is currently one of the most parsimonious models for spatial epidemic spread. This model uses distance-weighted, population size-dependent coupling to estimate host movement and disease incidence in metapopulations. The model captures overall measles dynamics in terms of underlying human movement in pre-vaccination England and Wales (previously established). In spatial models, edges often present a special challenge. Therefore, to test the model's robustness, we analyzed gravity model incidence predictions for coastal cities in England and Wales. Results show that, although predictions are accurate for inland towns, they significantly underestimate coastal persistence. We examine incidence, outbreak seasonality, and public transportation records, to show that the model's inaccuracies stem from an underestimation of total contacts per individual along the coast. We rescue this predicted 'edge effect' by increasing coastal contacts to approximate the number of per capita inland contacts. These results illustrate the impact of 'edge effects' on epidemic metapopulations in general and illustrate directions for the refinement of spatiotemporal epidemic models.     

Fallout radiocesium in an Antarctic region:

To improve the knowledge about the (137)Cs spatial distribution and vertical migration in soils of the Southern Hemisphere, the total areal activity density and the vertical transport parameters of this radionuclide were measured in an Antarctic region. For this purpose vegetation and incremental soil samples were collected at 21 representative sites located at 4 islands of the South Shetland Archipelago: King George, Robert, Greenwich and Snow (62-63 degrees S and 58-62 degrees W). The total (137)Cs activity density varied considerably from 118 to 662 Bq m(-2) (median 384 Bq m(-2), reference date 1995), with a high percentage of the total activity retained in the vegetation cover (5-98% in moss, 3-20% in lichen and 4-12% in grass). At most sites, the maximum activity density in soil was observed in the top layer from where it decreased continuously. To evaluate the transport parameters of (137)Cs from the activity-depth profiles, the classical convection-diffusion model was used based on the time-course of the annual deposition density of (137)Cs at the studied region. The values for the diffusion coefficient D(s) (median 0.043 cm(2) year(-1)) and the convection velocity v(s) (median -0.012 cm year(-1)) of radiocesium observed under a polar climate are small compared to the transport parameters determined in temperate zones. The data also indicate that at these sites the convectional transport of (137)Cs is almost negligible compared to the transport by diffusion. The high vulnerability of the Antarctic soils to (137)Cs deposition, as a consequence of its very slow transport due to the extreme climatic conditions at these latitudes, has been confirmed.     

Genotypic effects in phytoavailability of radiocaesium are pronounced at low K intensities in soil

The differences in radiocaesium uptake between species were analysed in a series of solution culture and pot trials. Since radiocaesium uptake is very sensitive to the solution potassium (K) concentration, it was hypothesised that species depleting K in the rhizosphere to a larger extent, will have a higher radiocaesium uptake. Five species (bean, lettuce, winter barley, ryegrass and bentgrass) were grown for 18–21 days in nutrient solution spiked with ¹³⁷Cs and at 4 K concentrations between 0.025 and 1.0 mM. Shoot ¹³⁷Cs activities all decreased between 17- and 81-fold with increasing K supply. Shoot ¹³⁷Cs activities were 4-fold different between species at the lowest K supply and 3.4-fold different at high K supply. The same five species were grown in two ¹³⁴Cs spiked soils with contrasting exchangeable K but similar clay content. Shoot ¹³⁴Cs activities were up to 19-fold higher in the soil with lowest exchangeable K. Differences in shoot activity concentrations between the species were only 4.5-fold in the high K soil, but were 15-fold in the low K soil. Bulk soil solution ¹³⁴Cs and K concentration data were combined with radiocaesium uptake characteristics measured in solution culture to predict radiocaesium uptake from soil. Predictions were within 1.6-fold of observations in the high K soil but largely underestimated ¹³⁴Cs uptake in lettuce, ryegrass and barley in the low K soil. A solute transport model was used to estimate K and radiocaesium concentrations in the rhizosphere. These calculations confirmed the assumption that higher radiocaesium uptake is found for species that deplete K in the rhizosphere to a larger extent.     

Isolation of Listeria monocytogenes from raw milk and its environment at dairy farms in Japan

The incidence of Listeria monocytogenes contamination in raw milk from farm bulk tanks and silage was investigated monthly at 20 dairy farms in Aomori prefecture, Japan, from January to July in 1989. Listeria sp. was isolated from one sample (5%) of raw milk collected in May, but L. monocytogenes was not isolated from raw milk. L. monocytogenes was isolated from two samples of silage (10%) collected in June. Silage, cow feces, sawdust bedding, dust and soil in these farms were tested for listerias, and we confirmed listerias contamination of the environment in the dairy farms.     

Long-term estimation of soil heat flux by single layer soil temperature

Soil heat flux is one of the important components of surface energy balance. In this study, long-term estimation of soil heat flux from single layer soil temperature was carried out by the traditional sinusoidal analytical method and the half-order time derivative method of Wang and Bras [Wang and Bras (1999) J Hydrol 216:214–226]. In order to understand the characteristics of soil heat flux and to examine the performances of the two methods, a field experiment was conducted at a temperate and humid grassland in Cork, Ireland. Our results show that the soil heat flux had the same magnitude as the sensible heat flux at this grassland site. It was also demonstrated that the analytical method did not predict the soil heat flux well because the sinusoidal assumption for the temporal variation in soil heat flux was invalid. In contrast, good agreement was found between the soil heat flux measurements and predictions made by the half-order time derivative method. This success suggests that this method could be used to estimate soil heat flux from long-term remotely sensed surface temperature.     

Variation in the metabolism of radiocaesium between individual sheep

Considerable variability has been recorded in the radiocaesium activity concentration of muscle between individual sheep in the same flocks in upland areas that received fallout from the Chernobyl accident. In a previous paper we demonstrated that there is a propensity for certain sheep within a flock to be always amongst the most contaminated and others to be consistently the least contaminated. Here we report a study to determine the extent to which variation in the metabolism of radiocaesium by individual sheep may contribute to the observed variability within sheep flocks. The transfer coefficient and biological half-life of orally administered ionic radiocaesium in muscle were determined under controlled conditions in 22 ewes from an upland farm in an area of the UK which received comparatively high levels of Chernobyl fallout. There was considerable variation between individuals in both the transfer coefficient (0.19–0.56 day⋅kg^–1; mean 0.34 day⋅kg^–1) and biological half-life in muscle (5.2– 18.7 days; mean 9.8 days). Changes in liveweight during the study and feed intake together accounted for 72% of the variation in the derived transfer coefficients; liveweight change also accounted for 56% of the observed variation in biological half-life. In a subsequent study, the true absorption coefficient of radiocaesium was determined in 12 of the ewes. There was a positive correlation between transfer and true absorption coefficients (R=0.57). We conclude that differences in the metabolism of radiocaesium will contribute to the observed variability in radiocaesium activity concentrations within sheep flocks in areas which were contaminated by Chernobyl fallout. We also suggest that for growing animals, the influence of liveweight change and feed intake on radiocaesium transfer may be greater than observed here. Similarly, in dairy cattle, for which feed intake changes considerably during the course of a lactation, large temporal variation in radiocaesium transfer to milk could be expected. Received: 10 August 1998 / Accepted in revised form: 20 October 1998     

Predicting insect phenology across space and time

Many species appear to be undergoing shifts in phenology, arising from climate change. To predict the direction and magnitude of future changes requires an understanding of how phenology depends on climatic variation. Species show large‐scale spatial variation in phenology (affected by differentiation among populations) as well as variation in phenology from year‐to‐year at the same site (affected predominantly by local plasticity). Teasing apart spatial and temporal variation in phenology should allow improved predictions of phenology under climate change. This study is the first to quantify large‐scale spatial and temporal variation in the entire emergence pattern of species, and to test the relationships found by predicting future data. We use data from up to 33 years of permanent transect records of butterflies in the United Kingdom to fit and test models for 15 butterfly species. We use generalized additive models to model spatial and temporal variation in the distribution of adult butterflies over the season, allowing us to capture changes in the timing of emergence peaks, relative sizes of peaks and/or number of peaks in a single analysis. We develop these models using data for 1973–2000, and then use them to predict phenologies from 2001 to 2006. For six of our study species, a model with only spatial variation in phenology is the best predictor of the future, implying that these species have limited plasticity. For the remaining nine species, the best predictions come from a model with both spatial and temporal variation in phenology; for four of these, growing degree‐days have similar effects over space and time, implying high levels of plasticity. The results show that statistical phenology models can be used to predict phenology shifts in a second time period, suggesting that it should be feasible to project phenologies under climate change scenarios, at least over modest time scales.     

A theoretical analysis of the morph frequency variation in the peppered moth over England and Wales

The migration-selection model for the spatial and temporal variation of morph frequencies of Biston betularia over England and Wales (Cook & Mani, 1980) has been extended to include effects due to non-visual selection. The parameters for non-visual selection were chosen from the recent determination by Mani (1980) and by Creed et al . (1980). The morph frequencies over England and Wales were obtained through computer simulation and the results were compared with data along the Manchester-Yorkshire, Central Wales-East Anglia and South Wales-London transects. Best fits to the data were obtained by using the non-visual selective values of Mani for carbonaria and modified values of Creed et al . for insularia . It is concluded that the observed polymorphism could be well explained through a balance of migration and visual and non-visual selections.     

Responses of soil microorganisms to resource availability in urban, desert soils

Terrestrial desert ecosystems are strongly structured by the distribution of plants, which concentrate resources and create islands of fertility relative to interplant spaces. Atmospheric nitrogen (N) deposition resulting from urbanization has the potential to change those spatial patterns via resource inputs, resulting in more homogeneous soil resource availability. We sampled soils at 12 desert remnant sites around Phoenix, Arizona along a model-predicted gradient in N deposition to determine the degree to which deposition has altered spatial patterns in soil resource availability and microbial activity. Soil microbial biomass and abundance were not influenced by atmospheric N deposition. Instead, plant islands remained strong organizers of soil microbial processes. These islands of fertility exhibited elevated pools of resources, microbial abundance, and activity relative to interspaces. In both plant islands and interspaces, soil moisture and soil N concentrations predicted microbial biomass and abundance. Following experimental wetting, carbon dioxide (CO₂) flux from soil of interspaces was positively correlated with N deposition, whereas in plant islands, soil CO₂ flux was positively correlated with soil moisture content and soil organic matter. Soil CO₂ flux in both patch types showed rapid and short-lived responses to precipitation, demonstrating the brief time scales during which soil biota may process deposited materials. Although we observed patterns consistent with N limitation of microbes in interspaces, we conclude that atmospheric N deposition likely accumulates in soils because microbes are primarily limited by water and secondarily by carbon or nitrogen. Soil microbial uptake of atmospherically deposited N likely occurs only during sparse and infrequent rainfall.     

Hunt sightings as a tool for monitoring the distribution and abundance of brown hare <Emphasis Type="Italic">Lepus europaeus</Emphasis> in UK agricultural landscapes

We examined the potential of hare sightings data, collected during hunts by the Association of Masters of Harriers and Beagles, as a possible monitoring tool for the European brown hare Lepus europaeus. The relationship between land use and both temporal trends, and spatial patterns, in brown hare sightings across England and Wales was examined using data collected between the 1985/86 and 2004/05 hunting seasons. Hare sightings increased significantly during this period, with an average increase of 2.81 hare sightings per hunting day across all hunts since 1985. Sightings were more frequent in eastern England, where arable land is abundant, than in the rest of England and Wales which is predominantly pastoral. There was no correlation between temporal trends in hare sightings and land use change. Patterns observed using the hunt sighting data are similar to those reported by other concurrent studies that used different methods. We conclude that hunt sightings could contribute useful data to a national monitoring scheme.     

Changes in soil pH across England and Wales in response to decreased acid deposition

Analysis of data from the National Soil Inventory of England and Wales obtained between 1978 and 2003 shows widespread increases in soil pH – i.e., soils became less acid – across both countries during the survey period. In general, soil pH increased under all land uses. At least part of the increase and its regional variation could be explained by decreased sulphur deposition from the atmosphere. Changes in liming practices on arable land probably also contributed. The effect of decreased sulphur deposition was moderated by land use, soil properties – particularly soil pH and organic carbon content – and the level of past sulphur deposition.     

青岛地区慢性荨麻疹患者食物不耐受结果分析

目的:探讨青岛地区慢性荨麻疹患者与食物不耐受的相关性。方法:选取慢性荨麻疹患者496名,采用酶联免疫吸附试验检测血清中14种食物特异性IgG。结果:385例患者食物不耐受阳性,以鸡蛋、牛奶、螃蟹、鳕鱼、大豆为主,分别占55.0%、28.6%、26.8%、19.5%、15.1%;不同年龄组中不耐受的食物所占的比例不同;其中,儿童组:以鸡蛋(84.0%)、牛奶(59.0%)、螃蟹、大豆(16.0%)、鳕鱼(15.3%)为主;青年组:以鸡蛋(55.1%)、牛奶(29.1%)、螃蟹(27.6%)、鳕鱼(22.8%)为主;中年组:以鸡蛋(39.9%)、螃蟹(32.5%)、鳕鱼(18.4%)、大豆(12.9%)为主;老年组:以螃蟹(35.5%)、鸡蛋(27.4%)、大豆(19.4%)、鳕鱼(17.7%)为主。结论:通过检测分析患者血清中特异性IgG,发现青岛及其周边地区慢性荨麻疹患者不耐受的食物以海产品为主,且随年龄增长其敏感性逐渐增加。