Response of spring wheat and potato to foliar application of Zn, Mn and EDTA fertilizers on 137Cs uptake

The impact of foliar fertilization with zinc (ZnSO₄) and manganese (MnSO₄ on ¹³⁷Cs uptake by spring wheat and potato was studied. The experiments were conducted during 3 years (2014-2016) in a¹³⁷Cs-contaminated area, Zhytomyr region of Ukraine. The fertilization was carried out on podzolic loamy sand soil, poor in most of the microelements. Both crops were fertilized at four successive stages of growth. Foliar application of fertilizers caused higher yield of wheat grain/straw and potato tubers yield in 2014-2015 years but had no effect in 2016. Thus, the overall effect of fertilization between 2014 and 2016 was less pronounced and generally insignificant. Application of Zn, Mn and EDTA reduced ¹³⁷Cs uptake by wheat grain and potato tubers, when fertilized at earlier stages of growth and development in years 2014 and 2015 by factor 1.5-2.0, while in 2016 the effect was generally statistically insignificant. It is suggested, that reduction of ¹³⁷Cs uptake by spring wheat and potato, at least partly, was caused by an effect of radionuclide dilution due to the higher biomass of the plants. A foliar spray of EDTA at earlier stages of plant growth and development may be considered as a potential countermeasure aiming reducing ¹³⁷Cs uptake from soil to plants, even if such effect appeared to be conditional.

Transfer of radionuclides and dose assessment to ants and anthills in a Swedish forest ecosystem

In forest ecosystems soil organisms are important for immobilization, translocation and recycling of radionuclides. Still, there is a lack of studies on the role of insects such as ants in the turnover of radionuclides and how radioactivity affects an ant community. In this study seven anthills were sampled in an area that was heavily contaminated after the fallout from the Chernobyl accident. Samples of ant and anthill materials were taken from different depths of the anthills as well as from the surrounding soil and the activity concentrations of ¹³⁷Cs were determined. In addition, a radiation dose assessment was performed for ants and anthills using the ERICA tool. The deposition of ¹³⁷Cs in 1986 in the study area was calculated back to be on average 110,500 Bq m^-2. The averaged data for all the seven locations investigated indicate that the level of ¹³⁷Cs activity concentrations in the anthill's material increased with depth of the anthill being highest at the depth 50-65 cm. The concentration in the upper layers (0-2 cm) and of the ants showed significant correlations with the deposition upon multivariate analysis. The concentration ratio (CR) defined as the ratio between the mass activity for ¹³⁷Cs density in ants (Bq kg^-1 d.w.) and mass activity density in soil (Bq kg^-1 d.w.) was determined to be in the range of 0.04-0.14. Also, the transfer factor (TF) defined as the ratio between the mass activity for ¹³⁷Cs density in ant (Bq kg^-1 d.w.) and to the unit area activity density (in Bq m^-2 d.w.) was determined for ¹³⁷Cs to be 0.0015 m² kg^-1 d.w. The assessed radiation doses were found to be a 4.9 μGy h^-1 which is below international reference levels for non-human biota.

Response to omalizumab using patient enrichment criteria from trials of novel biologics in asthma

Background

Recent efficacy studies of asthma biologics have included highly enriched patient populations. Using a similar approach, we examined factors that predict response to omalizumab to facilitate selection of patients most likely to derive the greatest clinical benefit from therapy.

Methods

Data from two phase III clinical trials of omalizumab in patients with allergic asthma were examined. Differences in rates of asthma exacerbations between omalizumab and placebo groups during the 16‐week inhaled corticosteroid (ICS) dose‐stable phase were evaluated with respect to baseline blood eosinophil counts (eosinophils <300/μL [low] vs ≥300/μL [high]) and baseline markers of asthma severity (emergency asthma treatment in prior year, asthma hospitalization in prior year, forced expiratory volume in 1 second [FEV₁; FEV₁ <65% vs ≥65% predicted], inhaled beclomethasone dipropionate dose [<600 vs ≥600 μg/day], and long‐acting beta‐agonist [LABA] use [yes/no]).

Results

Adults/adolescents (N = 1071) were randomized to receive either omalizumab (n = 542) or placebo (n = 529). In the 16‐week ICS dose‐stable phase, rates of exacerbations requiring ≥3 days of systemic corticosteroid treatment were 0.066 and 0.147 with omalizumab and placebo, respectively, representing a relative rate reduction in omalizumab‐treated patients of 55% (95% CI, 32%‐70%; P = .002). For patients with eosinophils ≥300/μL or with more severe asthma, this rate reduction was significantly more pronounced.

Conclusion

In patients with allergic asthma, baseline blood eosinophil levels and/or clinical markers of asthma severity predict response to omalizumab.

Rapid gamma spectrometric analysis of soil samples after radioactive fallout using a "conjugate view" technique

A method for fast determination of the activity in soil samples by measuring a fresh soil core sample from both ends with an HPGe-detector is proposed. The method was tested by simulations, as well as by measurements on spiked soil samples. Both simulations and measurements showed that the geometrical mean of the count rates when the sample is measured twice, with the bottom and the top end, respectively, facing the detector closely resembles the count rate from a measurement on a homogenized sample. Therefore, an efficiency calibration for homogenized samples could be used even if the activity is highly inhomogeneous in the soil core, as is the case with fresh fallout. It was also shown that by studying the ratio between the two measurements, a rough estimation of the extent of penetration of the radionuclide in the soil can be found. This will enhance the possibility to make rapid estimations of the soil inventory by field gamma spectrometry.

Omalizumab in children with uncontrolled allergic asthma: Review of clinical trial and real-world experience

Asthma is one of the most common chronic diseases of childhood. Allergen sensitization and high frequencies of comorbid allergic diseases are characteristic of severe asthma in children. Omalizumab, an anti-IgE mAb, is the first targeted biologic therapeutic approved for the treatment of moderate-to-severe persistent allergic asthma (AA) that remains uncontrolled despite high-dose inhaled corticosteroids plus other controller medications. Since its initial licensing for use in adults and adolescents 12 years of age and older, the clinical efficacy, safety, and tolerability of omalizumab have been demonstrated in several published clinical trials in children aged 6 to less than 12 years with moderate-to-severe AA. These studies supported the approval of the pediatric indication (use in children aged ≥6 years) by the European Medicines Agency in 2009 and the US Food and Drug Administration in 2016. After this most recent change in licensing, we review the outcomes from clinical trials in children with persistent AA receiving omalizumab therapy and observational studies from the past 7 years of clinical experience in Europe. Data sources were identified by using PubMed in 2016. Guidelines and management recommendations and materials from the recent US Food and Drug Administration's Pediatric Advisory Committee meeting are also reviewed.

Asthma Exacerbations and Triggers in Children in TENOR: Impact on Quality of Life

BACKGROUND

Data examining associations between asthma exacerbations, triggers, and asthma-related quality of life (QOL) in children with severe/difficult-to-treat asthma are unavailable.

OBJECTIVE

To evaluate real-world data on relationships between asthma exacerbations, triggers, and QOL in children using data from TENOR (The Epidemiology and Natural History of Asthma Outcomes and Treatment Regimens), a 3-year observational study of patients with severe/difficult-to-treat asthma, including those aged 6 to 12 years.

METHODS

QOL was examined using the Pediatric Asthma Quality of Life Questionnaire (PAQLQ) and defined exacerbations hierarchically (descending order of severity): hospitalization, emergency department visit, steroid burst, no exacerbation, using the highest value from months 6 and 12. One-way ANOVA was used to test for differences in PAQLQ domain scores at month 12 across exacerbation severity, total number of asthma exacerbations, and number of baseline asthma triggers. Mantel-Haenszel chi-square test was used to test the association between the number of triggers and exacerbation hierarchy.

RESULTS

Greater severity of asthma exacerbations was associated with significantly (P < .001) lower mean PAQLQ domain scores, indicating poorer QOL. A higher number of asthma exacerbations was associated with significantly (P < .001) lower mean PAQLQ domain scores. PAQLQ scores were significantly lower with higher numbers of baseline triggers. Higher baseline number of asthma triggers was associated with greater severity (P = .05) and number of asthma exacerbations (P < .001).

CONCLUSIONS

A higher number of asthma triggers at baseline was associated with greater asthma severity and number of asthma exacerbations and lower QOL in children with severe/difficult-to-treat asthma.

A randomized multicenter study evaluating Xolair persistence of response after long-term therapy

BACKGROUND

Few data are available to assist clinicians with decisions regarding long-term use of asthma therapies, including omalizumab.

OBJECTIVE

We sought to evaluate the benefit and persistence of response in subjects continuing or withdrawing from long-term omalizumab treatment.

METHODS

Evaluating the Xolair Persistency Of Response After Long-Term Therapy (XPORT) was a randomized, double-blind, placebo-controlled withdrawal study that included subjects with moderate-to-severe persistent asthma receiving long-term omalizumab. Subjects were randomized by using a hierarchical dynamic randomization scheme to continue their same dose of omalizumab or withdraw to placebo and were then followed every 4 weeks for 1 year. The primary outcome was any protocol-defined severe asthma exacerbation. The secondary outcome was time to first protocol-defined severe asthma exacerbation. Exploratory outcomes included changes in Asthma Control Questionnaire and Asthma Control Test scores.

RESULTS

Significantly more subjects in the omalizumab group (67%) had no protocol-defined exacerbation than in the placebo group (47.7%); an absolute difference of 19.3% (95% CI, 5.0%, 33.6%) represents a 40.1% relative difference. Time to first protocol-defined exacerbation analysis revealed a significantly different between-group exacerbation pattern that was consistent with the primary analysis. Subjects continuing omalizumab had significantly better asthma control (mean [SD] change from baseline to week 52: Asthma Control Test score, -1.16 [4.14] vs placebo, -2.88 [5.38], P = .0188; Asthma Control Questionnaire score, 0.22 [0.66] vs placebo, 0.63 [1.13], P = .0039). Discontinuation of omalizumab was associated with an increase in free IgE levels and an increase in basophil expression of the high-affinity IgE receptor. No safety concerns were noted.

CONCLUSION

Continuation of omalizumab after long-term treatment results in continued benefit, as evidenced by improved symptom control and reduced exacerbation risk.

Improvement of sleep in patients with chronic idiopathic/spontaneous urticaria treated with omalizumab: results of three randomized, double-blind, placebo-controlled studies

Background

Patients with chronic idiopathic/spontaneous urticaria (CIU/CSU) report difficulty with sleep.

Methods

We examined the effect of omalizumab on sleep-related outcomes during 3–6 months omalizumab or placebo treatment and a 16-week follow-up period within three Phase III double-blind randomized placebo-controlled pivotal trials in CIU/CSU: ASTERIA I, ASTERIA II, and GLACIAL. Sleep quality was assessed in all three studies using sleep-related questions included in an electronic diary, the Chronic Urticaria Quality of Life Questionnaire, and the Medical Outcomes Study Sleep Scale. Score changes from baseline in the treatment arms were compared with that in the placebo arm and adjusted for baseline score and weight. We also examined correlations of sleep scores at baseline, week 12, and week 24 and the slopes of change between sleep and itch and hive.

Results

Patients treated with omalizumab reported a larger reduction in sleep problems than those in the placebo arm; omalizumab 300 mg demonstrated the greatest improvement on all sleep components among all treatment arms. The largest reduction in sleep problems was reported within the first 4 weeks of therapy. After treatment discontinuation, sleep quality worsened. Sleep scores demonstrated moderate-to-strong correlation between them, and the change in sleep scores was associated with changes in itch and hives.

Conclusions

Improvement in sleep was reported after the first dose of omalizumab. Sleep continued to improve throughout the active treatment period. Patients receiving omalizumab 300 mg achieved greater improvement in sleep than those in other treatment arms.

Trial registration ClinicalTrials.gov, NCT01287117 (ASTERIA I), NCT01292473 (ASTERIA II), and NCT01264939 (GLACIAL)

Electronic supplementary material

The online version of this article (doi:10.1186/s13601-016-0120-0) contains supplementary material, which is available to authorized users.

Interception and transfer of wet-deposited (134)Cs to potato foliage and tubers

Contamination levels on potato foliage and tubers were investigated by repeated sampling after multiple foliar contaminations of wet-deposited (134)Cs at five different growth stages in a micro-plot field experiment in three successive years. Application of the radionuclide early in the growing season (deposition date 19-27 June, growth stage II = plant establishment) resulted in low (134)Cs activity concentration in potato tubers across sampling occasions (mean 60, 25 and 115 Bq kg(-1) dry weight (D.W.) for years 1, 2 and 3, respectively). Following radionuclide deposition in the middle of the growing season (15-24 July, growth stage III = tuber initiation), (134)Cs activity concentration in tubers across sampling occasions was found to be highest (mean 150, 850 and 660 Bq kg(-1) D.W. for years 1, 2 and 3, respectively). When the radionuclide was sprayed on at later stages (5-7 August, growth stage IV = tuber bulking), (134)Cs activity concentrations in tubers across sampling dates decreased (mean 75, 310 and 395 Bq kg(-1) D.W. for years 1, 2 and 3, respectively). Deposition in the second half of August (15-28 August, late growth stage IV and beginning of growth stage V = tuber maturation) resulted in yet lower (134)Cs activity concentration in tubers. Potato tubers may concentrate as much as up to 2 times more (134)Cs than foliage depending on deposition date of radionuclide.

Similar Efficacy with Omalizumab in Chronic Idiopathic/Spontaneous Urticaria Despite Different Background Therapy

BACKGROUND

Data from the 3 omalizumab pivotal trials in patients with chronic idiopathic urticaria/chronic spontaneous urticaria (CIU/CSU) represent the largest database of patients reported to date with refractory disease (omalizumab, n = 733; placebo, n = 242).

OBJECTIVE

The objective of this study was to compare results from ASTERIA I and II, which included only approved doses of H1-antihistamine as background therapy based on regulatory authority requirements, to those from GLACIAL, which permitted higher doses of H1-antihistamines as well as other types of background therapy, in a post hoc analysis.

METHODS

Efficacy data from the placebo, omalizumab 150-mg, and omalizumab 300-mg treatment arms of ASTERIA I and II were pooled and analyzed (n = 162 and n = 160, respectively). The 300-mg treatment arm analyses were compared with the analysis of data from GLACIAL (n = 252) using analysis of covariance models. The key efficacy endpoint was change from baseline to week 12 in mean weekly itch severity score (ISS); other endpoints were also evaluated. Safety data were pooled from all 3 studies.

RESULTS

Mean ISS was significantly reduced from baseline at week 12 in the pooled ASTERIA I and II omalizumab 150- and 300-mg treatment arms and in the GLACIAL omalizumab 300-mg arm. The weekly ISS reduction magnitude at week 12 was similar between the omalizumab 300-mg groups in the ASTERIA I and II pooled and GLACIAL studies. Similar treatment effect sizes were observed across multiple endpoints. Omalizumab was well tolerated and the adverse-event profile was similar regardless of background therapy for CIU/CSU. The overall safety profile was generally consistent with omalizumab therapy in allergic asthma.

CONCLUSION

Omalizumab 300 mg was safe and effective in reducing CIU/CSU symptoms regardless of background therapy.

Efficacy and safety of omalizumab in patients with chronic idiopathic/spontaneous urticaria who remain symptomatic on H1 antihistamines: a randomized, placebo-controlled study

ASTERIA I was a 40-week, randomized, double-blind, placebo-controlled study to evaluate the efficacy and safety of subcutaneous omalizumab as add-on therapy for 24 weeks in patients with chronic idiopathic urticaria/spontaneous urticaria (CIU/CSU) who remained symptomatic despite H1 antihistamine treatment at licensed doses. Patients aged 12-75 years with CIU/CSU who remained symptomatic despite treatment with approved doses of H1 antihistamines were randomized (1:1:1:1) in a double-blind manner to subcutaneous omalizumab 75 mg, 150 mg, or 300 mg or placebo every 4 weeks for 24 weeks followed by 16 weeks of follow-up. The primary end point was change from baseline in weekly itch severity score (ISS) at week 12. Among randomized patients (N=319: placebo n=80, omalizumab 75 mg n=78, 150 mg n=80, 300 mg n=81), 262 (82.1%) completed the study. Compared with placebo (n=80), mean weekly ISS was reduced from baseline to week 12 by an additional 2.96 points (95% confidence interval (CI): -4.71 to -1.21; P=0.0010), 2.95 points (95% CI: -4.72 to -1.18; P=0.0012), and 5.80 points (95% CI: -7.49 to -4.10; P<0.0001) in the omalizumab 75-mg (n=77), 150-mg (n=80), and 300-mg groups (n=81), respectively. The omalizumab 300-mg group met all nine secondary end points, including a significant decrease in the duration of time to reach minimally important difference response (⩾5-point decrease) in weekly ISS (P<0.0001) and higher percentages of patients with well-controlled symptoms (urticaria activity score over 7 days (UAS7) ⩽6: 51.9% vs. 11.3%; P<0.0001) and complete response (UAS7=0: 35.8% vs. 8.8%; P<0.0001) versus placebo. During the 24-week treatment period, 2 (2.9%), 3 (3.4%), 0, and 4 (5.0%) patients in the omalizumab 75-mg, 150-mg, 300-mg, and placebo groups, respectively, experienced a serious adverse event. Omalizumab 300 mg administered subcutaneously every 4 weeks reduced weekly ISS and other symptom scores versus placebo in CIU/CSU patients who remained symptomatic despite treatment with approved doses of H1 antihistamines.

Potassium fertilization and (137)Cs transfer from soil to grass and barley in Sweden after the Chernobyl fallout

Fertilization of soils contaminated by radionuclides with potassium (K) and its effect on (137)Cs transfer from soil to crops is well studied in field conditions; however experiments over many years are few. The effects of potassium fertilization on cesium-137 ((137)Cs) transfer to hay, pasture grass, and barley growing on organic rich soils and mineral sand and loam soils in a number of field experimental sites situated in different environments in Sweden are summarized and discussed. The basic experimental treatments were control (no K fertilizers were applied), 50, 100, and 200 kg K ha(-1). In the experiment, which lasted over 3-6 years, (137)Cs transfer factors in control treatments ranged between 0.0004 m(2) kg(-1) (barley grain on sand soil) and 0.07 m(2) kg(-1) (pasture grass on organic rich soil). Potassium application on soils with low clay content i.e. mineral sand and organic rich soils was effective at the 50-100 kg ha(-1) level. Application of 200 kg K ha(-1) resulted in a five-fold reduction in (137)Cs transfer for hay and up to four-fold for barley grain. The effects of potassium application were generally greater on sand than organic rich soil and were observed already in the first cut. After K application, the reduction in (137)Cs transfer to crops was correlated with (137)Cs:K ratios in plant material. Additional application of zeolite caused a 1.4 reduction of (137)Cs transfer to hay on sand and 1.8-fold reduction on organic rich soil; whereas, application of potash-magnesia and CaO had no effect.

Inoculation with arbuscular mycorrhizae does not improve 137Cs uptake in crops grown in the Chernobyl region

Methods for cleaning up radioactive contaminated soils are urgently needed. In this study we investigated whether the use of arbuscular mycorrhizal (AM) fungi can improve (137)Cs uptake by crops. Barley, cucumber, perennial ryegrass, and sunflower were inoculated with AM fungi and grown in low-level radionuclide contaminated soils in a field experiment 70 km southwest of Chernobyl, Ukraine, during two successive years (2009-2010). Roots of barley, cucumber and sunflower plants were slightly or moderately infected with AM fungus and root infection frequency was negatively or non-correlated with (137)Cs uptake by plants. Roots of ryegrass were moderately infected with AM fungus and infection frequency was moderately correlated with (137)Cs uptake by ryegrass. The application of AM fungi to soil in situ did not enhance radionuclide plant uptake or biomass. The responsiveness of host plants and AM fungus combination to (137)Cs uptake varied depending on the soil, although mycorrhization of soil in the field was conditional and did not facilitate the uptake of radiocesium. The total amount of (137)Cs uptake by plants growing on inoculated soil was equal to amounts in plant cultivated on non-inoculated soil. Thus, the use of AM fungi in situ for bioremediation of soil contaminated with a low concentration of (137)Cs could not be recommended.

Exploring the effects of omalizumab in allergic asthma: an analysis of biomarkers in the EXTRA study

RATIONALE

For many patients with asthma, allergic airway inflammation is primarily a Th2-weighted process; however, heterogeneity in patterns of inflammation suggests phenotypic distinctions exist that influence disease presentation and treatment effects.

OBJECTIVES

To assess the potential of fractional exhaled nitric oxide (FE(NO)), peripheral blood eosinophil count, and serum periostin as biomarkers of Th2 inflammation and predictors of treatment effects of omalizumab.

METHODS

The EXTRA omalizumab study enrolled patients (aged 12-75 yr) with uncontrolled severe persistent allergic asthma. Analyses were performed evaluating treatment effects in relation to FE(NO), blood eosinophils, and serum periostin at baseline. Patients were divided into low- and high-biomarker subgroups. Treatment effects were evaluated as number of protocol-defined asthma exacerbations during the 48-week treatment period (primary endpoint).

MEASUREMENTS AND MAIN RESULTS

A total of 850 patients were enrolled. Data were available from 394 (46.4%), 797 (93.8%), and 534 (62.8%) patients for FE(NO), blood eosinophils, and serum periostin, respectively. After 48 weeks of omalizumab, reductions in protocol-defined exacerbations were greater in high versus low subgroups for all three biomarkers: FE(NO), 53% (95% confidence interval [CI], 37-70; P = 0.001) versus 16% (95% CI, -32 to 46; P = 0.45); eosinophils, 32% (95% CI, 11-48; P = 0.005) versus 9% (95% CI, -24 to 34; P = 0.54); and periostin, 30% (95% CI, -2 to 51; P = 0.07) versus 3% (95% CI, -43 to 32; P = 0.94).

CONCLUSIONS

The difference in exacerbation frequency between omalizumab and placebo was greatest in the three high-biomarker subgroups, probably associated with the greater risk for exacerbations in high subgroups. Additional studies are required to explore the value of these biomarkers in clinical practice. Clinical trial registered with www.clinicaltrials.gov (NCT00314574).

Omalizumab for the treatment of chronic idiopathic or spontaneous urticaria

BACKGROUND

Many patients with chronic idiopathic urticaria (also called chronic spontaneous urticaria) do not have a response to therapy with H-antihistamines, even at high doses. In phase 2 trials, omalizumab, an anti-IgE monoclonal antibody [corrected] that targets IgE and affects mast-cell and basophil function, has shown efficacy in such patients.

METHODS

In this phase 3, multicenter, randomized, double-blind study, we evaluated the efficacy and safety of omalizumab in patients with moderate-to-severe chronic idiopathic urticaria who remained symptomatic despite H-antihistamine therapy (licensed doses). We randomly assigned 323 patients to receive three subcutaneous injections, spaced 4 weeks apart, of omalizumab at doses of 75 mg, 150 mg, or 300 mg or placebo, followed by a 16-week observation period. The primary efficacy outcome was the change from baseline in a weekly itch-severity score (ranging from 0 to 21, with higher scores indicating more severe itching).

RESULTS

The baseline weekly itch-severity score was approximately 14 in all four study groups. At week 12, the mean (±SD) change from baseline in the weekly itch-severity score was -5.1±5.6 in the placebo group, -5.9±6.5 in the 75-mg group (P=0.46), -8.1±6.4 in the 150-mg group (P=0.001), and -9.8±6.0 in the 300-mg group (P<0.001). Most prespecified secondary outcomes at week 12 showed similar dose-dependent effects. The frequency of adverse events was similar across groups. The frequency of serious adverse events was low, although the rate was higher in the 300-mg group (6%) than in the placebo group (3%) or in either the 75-mg or 150-mg group (1% for each).

CONCLUSIONS

Omalizumab diminished clinical symptoms and signs of chronic idiopathic urticaria in patients who had remained symptomatic despite the use of approved doses of H-antihistamines. (Funded by Genentech and Novartis Pharma; ClinicalTrials.gov number, NCT01292473.).

Downward migration of radiocaesium in organic soils across a transect in Scotland

Following the accident at the Chernobyl nuclear power plant in 1986, radioactive materials including (137)Cs were distributed over large parts of the former Soviet Union and Europe. Due to the relatively long physical half-life of (137)Cs (30.1 y) measurable activity concentrations can still be observed in the natural environment. We have determined the depth distribution of (137)Cs from the testing of nuclear weapons in the atmosphere and Chernobyl, in eight highly-organic soils along an approximately east to west transect across the Central Highlands of Scotland. The (137)Cs activity concentrations in the soil profiles, corrected for radioactive decay to May 1986, were between 2.8 and 14.4 kBq m(-2). There were differences in the pattern of distribution of (137)Cs in the soil profiles. The mean migration depth of (137)Cs in the soil profiles was 12.2 cm with a range between 8.2 and 17.4 cm. Quantitative mineralogical analysis of the ash obtained after heating the soil to 400 °C indicated that clay minerals alone did not have a prime role in controlling the migration of (137)Cs down the profile.

Effect of arbuscular mycorrhizal (AM) fungi on 137Cs uptake by plants grown on different soils

The potential use of mycorrhiza as a bioremediation agent for soils contaminated by radiocesium was evaluated in a greenhouse experiment. The uptake of (137)Cs by cucumber, perennial ryegrass, and sunflower after inoculation with a commercial arbuscular mycorrhizal (AM) product in soils contaminated with (137)Cs was investigated, with non-mycorrhizal quinoa included as a "reference" plant. The effect of cucumber and ryegrass inoculation with AM fungi on (137)Cs uptake was inconsistent. The effect of AM fungi was most pronounced in sunflower: both plant biomass and (137)Cs uptake increased on loamy sand and loamy soils. The total (137)Cs activity accumulated within AM host sunflower on loamy sand and loamy soils was 2.4 and 3.2-fold higher than in non-inoculated plants. Although the enhanced uptake of (137)Cs by quinoa plants on loamy soil inoculated by the AM fungi was observed, the infection of the fungi to the plants was not confirmed.

137Cs in fungal sporocarps in relation to vegetation in a bog, pine swamp and forest along a transect

In this study, we estimated the relative importance of vegetation and fungi for radiocesium uptake and biological retention in adjacent bog, pine swamp, and forest. The measurements for (137)Cs activity concentration in sporocarps (i.e. fruitbodies of fungi) and vegetation along a bog to forest transect were combined with complementary published data to calculate estimates. Aboveground vegetation comprised 17.7% of the total fallout-derived radiocesium in the system in bog, 16.5% in pine swamp, and 40.6% in forest. In fungal sporocarps grown along a gradient, (137)Cs activity comprised <0.001% of the total radiocesium for peat bog, <0.02% for pine swamp, and 0.11% for forest. Total (137)Cs activity in sporocarps increased along the gradient due to increased production of sporocarps in the presence of trees from 0.006 (bog), 0.097 (pine swamp) and 0.67 (forest) g dwt m(-2). Based on calculation of the total vegetation biomass and through relationships between fungal biomass in sporocarps and as mycelia in soil, the total (137)Cs activity located in fungi was estimated as 0.1% in bog, 2% in pine swamp, and 11% in forest. An analysis of the time-dependency of (137)Cs in the sporocarps in forest between 1990 and 2011 suggested an ecological half-life for (137)Cs between 8 and 13 years. Although fungi comprised a relatively small fraction of the total radiocesium in the systems, its activity decreased slowly with time, and ecological residence time for (137)Cs in sporocarps of fungi was long, suggesting they will continue to contribute to the accumulation and cycling of this radionuclide in forest.

Uptake and translocation of 109Cd and stable Cd within tobacco plants (Nicotiana sylvestris)

The availability, uptake, and translocation of recently added ((109)Cd) and naturally occurring (stable) soil Cd within tobacco plants were compared. (109)Cd was added to soil in two treatments, A (0.25 MBq kg soil(-1) DW) and B (eight-fold dose): stable Cd was measured in both treatments. Both the added and the stable Cd were higher in leaves and reproductive structures of the plant than in stalks and roots. The uptake of (109)Cd was 5.3 kBq plant(-1) for treatment A and 36.7 kBq plant(-1) for treatment B, and about 26 μg plant(-1) for stable Cd. Leaves of the tobacco plants accumulated 40-45% of the total (109)Cd and about 50% of total stable Cd taken up by the plant. Cadmium concentration in the plant was three times higher than in roots and two times higher than the concentration in soil: the concentration in roots was lower than in the soil.

Correlations between potassium, rubidium and cesium ((133)Cs and (137)Cs) in sporocarps of Suillus variegatus in a Swedish boreal forest

An analysis of sporocarps of ectomycorrhizal fungi Suillus variegatus assessed whether cesium ((133)Cs and (137)Cs) uptake was correlated with potassium (K) or rubidium (Rb) uptake. The question was whether intraspecific correlations of Rb, K and (133)Cs mass concentrations with (137)Cs activity concentrations in sporocarps were higher within, rather than among, different fungal species, and if genotypic origin of sporocarps within a population affected uptake and correlation. Sporocarps (n = 51) from a Swedish forest population affected by the fallout after the Chernobyl accident were studied. The concentrations were 31.9 ± 6.79 g kg(-1) for K (mean ± SD, dwt), 0.40 ± 0.09 g kg(-1) for Rb, 8.7 ± 4.36 mg kg(-1) for (133)Cs and 63.7 ± 24.2 kBq kg(-1) for (137)Cs. The mass concentrations of (133)Cs correlated with (137)Cs activity concentrations (r = 0.61). There was correlation between both (133)Cs concentrations (r = 0.75) and (137)Cs activity concentrations (r = 0.44) and Rb, but the (137)Cs/(133)Cs isotopic ratio negatively correlated with Rb concentration. Concentrations of K and Rb were weakly correlated (r = 0.51). The (133)Cs mass concentrations, (137)Cs activity concentrations and (137)Cs/(133)Cs isotopic ratios did not correlate with K concentrations. No differences between, within or, among genotypes in S. variegatus were found. This suggested the relationships between K, Rb, (133)Cs and (137)Cs in sporocarps of S. variegatus is similar to other fungal species.

Long-term effects of single potassium fertilization on 137Cs levels in plants and fungi in a boreal forest ecosystem

We examined the long-term effects of a single application of potassium (K) fertilizer (100 kg K ha(-1)) in 1992 on (137)Cs uptake in a forest ecosystem in central Sweden. (137)Cs activity concentrations were determined in three low-growing perennial shrubs, heather (Calluna vulgaris), lingonberry (Vaccinium vitis-idaea) and bilberry (Vaccinium myrtillus), and in four wild fungal species (Cortinarius semisanguineus, Lactarius rufus, Rozites caperata and Suillus variegatus). Uptake of (137)Cs by plants and fungi growing on K-fertilized plots 17 years after application of the K fertilizer was significantly lower than in corresponding species growing in a non-fertilized control area. The (137)Cs activity concentration was 21-58% lower in fungal sporocarps and 40-61% lower in plants in the K-fertilized area compared with the control. Over the study period, this decrease in (137)Cs activity concentration was more consistent in plants than in fungi, although the effect was statistically significant and strongly pronounced in all species. The effect of K fertilization in reducing (137)Cs activity concentration in fungi and plants decreased over time but was still significant in 2009, 17 years after fertilization. This suggests that application of K fertilizer to forests is an appropriate and effective long-term measure to decrease radiocaesium accumulation in plants and fungi.

Accumulation of potassium, rubidium and caesium (133Cs and 137Cs in various fractions of soil and fungi in a Swedish forest

Radiocaesium ((137)Cs) was widely deposited over large areas of forest in Sweden as a result of the Chernobyl accident in 1986 and many people in Sweden eat wild fungi and game obtained from these contaminated forests. In terms of radioisotope accumulation in the food chain, it is well known that fungal sporocarps efficiently accumulate radiocaesium ((137)Cs), as well as the alkali metals potassium (K), rubidium (Rb) and caesium (Cs). The fungi then enhance uptake of these elements into host plants. This study compared the accumulation of these three alkali metals in bulk soil, rhizosphere, soil-root interface, fungal mycelium and sporocarps of mycorrhizal fungi in a Swedish forest. The soil-root interface was found to be distinctly enriched in K and Rb compared with the bulk soil. Potassium concentrations increased in the order: bulk soil<rhizosphere<fungal mycelium<soil-root interface<fungal sporocarps; and Rb concentration in the order: bulk soil<rhizosphere<soil-root interface<fungal mycelium<fungal sporocarps. Caesium was more or less evenly distributed within the bulk soil, rhizosphere and soil-root interface fractions, but was actively accumulated by fungi. Fungi showed a greater preference for Rb and K than Cs, so the uptake of (137)Cs could be prevented by providing additional Rb or K at contaminated sites. The levels of K, Rb, and Cs found in sporocarps were at least one order of magnitude higher than those in fungal mycelium. These results provide new insights into the use of transfer factors or concentration ratios. The final step, the transfer of alkali metals from fungal mycelium to sporocarps, raised some specific questions about possible mechanisms.

The distribution of (137)Cs, K, Rb and Cs in plants in a Sphagnum-dominated peatland in eastern central Sweden

We record the distribution of (137)Cs, K, Rb and Cs within individual Sphagnum plants (down to 20cm depth) as well as (137)Cs in vascular plants growing on a peatland in eastern central Sweden. In Calluna vulgaris(137)Cs was mainly located within the green parts, whereas Andromeda polifolia, Eriophorum vaginatum and Vaccinium oxycoccos showed higher (137)Cs activity in roots. Carex rostrata and Menyanthes trifoliata showed variable distribution of (137)Cs within the plants. The patterns of (137)Cs activity concentration distribution as well as K, Rb and Cs concentrations within individual Sphagnum plants were rather similar and were usually highest in the capitula and/or in the subapical segments and lowest in the lower dead segments, which suggests continuous relocation of those elements to the actively growing apical part. The (137)Cs and K showed relatively weak correlations, especially in capitula and living green segments (0-10cm) of the plant (r=0.50). The strongest correlations were revealed between (137)Cs and Rb (r=0.89), and between (137)Cs and stable Cs (r=0.84). This suggests similarities between (137)Cs and Rb in uptake and relocation within the Sphagnum, but that (137)Cs differs from K.

137Cs in a raised bog in central Sweden

The vertical distribution of (137)Cs activity in peat soil profiles and (137)Cs activity concentration in plants of various species was studied in samples collected at two sites on a raised bog in central Sweden. One site (open bog) was in an area with no trees and only a few sparsely growing plant species, while the other (low pine) was less than 100 m from the open bog site and had slowly growing Scots pine, a field layer dominated by some ericaceous plants and ground well-covered by plants. The plant samples were collected in 2004-2007 and were compared with samples collected in 1989 from the same open bog and low pine sites. Ground deposition of (137)Cs in 2005 was similar at both sites, 23,000 Bq m(-2). In the open bog peat profile it seems to be an upward transport of caesium since a clear peak of (137)Cs activity was found in the uppermost 1-4 cm of Sphagnum layers, whereas at the low pine site (137)Cs was mainly found in deeper (10-12 cm) layers. The migration rate was 0.57 cm yr(-1) at the open bog site and the migration centre of (137)Cs was at a depth of 10.7, while the rate at the low pine site was 0.78 cm yr(-1) and the migration centre was at 14.9 cm. Heather (Calluna vulgaris) was the plant species with the highest (137)Cs activity concentrations at both sites, 43.5 k Bq(-1) DM in 1989 decreasing to 20.4 in 2004-2007 on open bog and 22.3 k Bq kg(-1) DM in 1989 decreasing to 11.2 k Bq(-1) DM by the period 2004-2007 on the low pine site. (137)Cs transfer factors in plants varied between 0.88 and 1.35 on the open bog and between 0.48 and 0.69 m(2)kg(-1) DM at the low pine site.

Effect of clay content and wetting-and-drying on radiocaesium behaviour in a peat and a peaty podzol

The interaction of radiocaesium with peat under two moisture regimes was studied in laboratory experiments and by growing ryegrass in pot experiments to simulate changing field moisture conditions. A peat untreated and treated with 5% by weight of clay containing 46% illitic minerals, and a peaty podzol naturally containing 4.5% mineral matter on a dry weight basis were contaminated with (134)Cs and incubated. The soils were exposed to 8 wetting-and-drying cycles or kept constantly wet during 40 days. Extraction of the peat with 1 M CH(3)COONH(4) (pH 7) repeated after each wetting-and-drying cycle indicated increasing (134)Cs fixation with time of incubation. The peat treated with clay showed a much higher (134)Cs fixation than that without clay. The pot experiment with the incubated soils showed a (134)Cs transfer to ryegrass of the same order for the peaty podzol as for the peat treated with clay. For the peat untreated with clay the (134)Cs transfer to ryegrass was much greater. Wetting-and-drying the peat, with or without clay, increased the overall yield of grass and the concentration and uptake of (134)Cs over 5 consecutive harvests. K-fertilisation increased the yield of plant material (except for the peat with added clay), decreased the concentration of (134)Cs, but had no significant effect (p=0.05) on the resultant uptake of (134)Cs. Mixing clay with the surface layer of organic soils appears to be an effective means of decreasing radiocaesium transfer to field crops in fallout situations.

Uptake and distribution of 137Cs and 90Sr in salix viminalis plants

Agricultural areas in middle and northern parts of Sweden were contaminated with radionuclides after the Chernobyl accident in 1986. Alternative crops in these areas are biomass plantations with fast-growing Salix clones for energy purposes. The uptake and internal distribution of 137Cs and 90Sr in Salix viminalis were studied. Plants were grown in microplots under field conditions. The soils in the experimental site had been contaminated in 1961 with 35.7 and 13.4 MBq m(-2) of 137Cs and 90Sr, respectively. The experiment was carried out during three years. The plots were fertilised with 60 kg N ha(-1) and three treatments of K, consisting of 0, 80 and 240 kg K ha(-1) during the first two years. The activity concentration of 137Cs in the different plant parts varied between 140 and 20,000 Bq kg(-1) and was ranked in the following order: lowest in stems < cuttings < leaves < roots. The fine roots (0-1 mm) had the highest 137Cs activity concentration. One-year-old stems had higher 137Cs activity concentrations than two-year-old stems. The activity concentration of 137Cs in the plants was significantly affected by K-supply and was higher in the 0 kg K treatment than in the 80 or 240kg K treatment. Leaves contained more 90Sr than stems and cuttings.