PCBs and HCHs in a salt-marsh sediment record from South-Central Chile: use of tsunami signatures and 137Cs fallout as temporal markers

This paper documents the occurrence of polychlorinated biphenyl (PCB) and hexachlorocyclohexane (HCH) deposition inferred from a sedimentary record exposed in a salt-marsh trench in South-Central Chile. Sediments were carefully collected every 1 cm from the trench wall. The samples were analyzed for PCBs, HCHs, 137Cs, organic carbon and grain size. The 137Cs fallout and the sedimentary signature left by the 1960 Chilean tsunami were used as temporal markers to estimate the stratigraphic chronology and the sedimentation rates. PCBs were quantified by gas chromatography with electron capture detection (GC-ECD), and positive samples were confirmed by gas chromatography and mass spectrometry detection (GC-MS). Based on these results, PCBs and HCHs deposition over the last 40 years was estimated. No PCBs were detected below the tsunami signature. Total concentrations ranged from undetectable (ND) to 32 ng/g d.w. for PCBs and from undetectable (ND) to 1.29 ng/g d.w. for HCHs. The highest PCB concentrations were found in the upper 7 cm of the core. Even though PCBs were banned in 1982 as electrical fluids in Chile, total estimated PCB fluxes have increased approximately 20 times during the last 40 years: from undetectable values to 102.6 ng/cm2/year, reflecting that PCBs are still in use and being released into the environment.     

生物对137Cs的吸收和富集

螺蛳等供试生物能很快地吸收水体中的＾１３７Ｃｓ,并随着时间的延长而不断增加,吸收过程可用直线方程来表达,螺蛳、喜旱莲子草和金鱼藻可以用来净化被＾１３７Ｃｓ的吸收较少,其中稗草和喜旱莲子草较高;由于Ｋ＾＋与Ｃｓ＾＋之间的拮抗作用,帮可用施钾肥方法减少作物以土壤中＾１３７Ｃｓ的吸收。     

Rice uptake and distributions of radioactive 137Cs, stable 133Cs and K from soil

The distributions of radionuclides in plant components as to radionuclide transfer to animals are important for understanding the dynamics of radionuclides in an agricultural field. Most of the non-edible parts in these components are returned to the soil as organic fertilizer where they may again be utilized in the soil-plant pathway and/or are mixed with feed for livestock. Rice plants were grown in an experimental field and separated at harvest into different components, including polished rice, rice bran, hull, leaves, stem and root, and then the distributions of radioactive 137Cs, stable 133Cs and K in these components were determined. The distribution of 137Cs in polished rice and rice bran was similar to that of 133Cs, while that of K was different. The concentration ratios of 133Cs/K in leaf blade positions increased with aging, which means that the translocation rate of 133Cs in rice plants was slower than that of K. At harvest the distribution of dry weight in polished rice to entire rice plants was 34%, and the distributions of 133Cs in the polished rice and the non-edible parts were 7 and 93%, respectively, whereas those of K in the polished rice and the non-edible parts were 2 and 98%, respectively. Findings suggest that the transfer and distribution of 133Cs, not of K, provide better information on the long-term fate of 137Cs in an agricultural environment.     

Determination and analysis of sorption of 137Cs to soils in Hong Kong reservoir

Soils from a local reservoir had been analyzed for their physical and chemical properties, distribution coefficients Kd and sorption rates for 137Cs. It was found that soils in Hong Kong were relatively low in organic matter and more acidic than those in some other countries. In sorption experiments, the rates of decrease in water activity concentration were initially very high, higher for larger mass of soils added, and then slowed down. The larger the mass, the shorter was the time for equilibrium. Three isotherms had been obtained by varying one of the three parameters (initial water activity concentration, slurry ratio and particle size) at a time. For constant initial water activity concentration and random sizes, percent sorption increased with slurry ratio. For soils of constant mass and random sizes. percent sorption decreased with increasing initial water activity concentration. For constant initial water activity concentration and slurry ratio, percent sorption increased with decreasing size of soil particles. A simple logistic model was developed to explain some of the findings.     

Benthic macroinvertebrates as reference indicators for monitoring of anthropogenic isotope 137Cs contamination in the marine environment

Environmental Science and Pollution Research - Due to the limited studies dealing with isotopes levels in benthic macroinvertebrates other than Mytilus sp. in period 2011–2018,...     

Laboratory analyses of 137Cs uptake by sunflower, reed and poplar

The 137Cs uptake by three plant species (Phragmites australis L., Heliantus annus L., Populus simonii L.) was analyzed in a hydroponic medium (14 MBql(-1); 0.5 mM CsCl) during cultivation. The radioactivity disappearance from the medium was measured after 2, 4, 8, 16 and 32 days of cultivation. Radioactivity distribution within the plant was determined by autoradiography. We did not find differences between uptake of radioactive and stable caesium isotopes. Relations between the uptake of 137Cs and concentration of potassium and ammonium ions in medium were also tested. The highest uptake of radiocaesium by sunflower was obtained for medium with 1 mM K2SO4 (14.2%) and in case of ammonium ions for concentration ratio 6 mM NH4Cl : 3 mM NH4NO3 (13.2%). The obtained results make it possible to compare the capability and rate of 137Cs phytoremediation of different plant species.     

Long term investigation of 137Cs in chicken meat and eggs from northwest Croatia

Abstract

This paper presents the results of long-term investigations of ¹³⁷Cs activity concentrations in chicken meat and eggs from northwest Croatia for the period 1987–2018. The research has been done as a part of monitoring program of radioactive contamination in Croatia. The highest activity concentrations in both of these foodstuffs were measured in 1987 and have been decreasing exponentially ever since. The Fukushima-Daiichi accident in 2011 did not cause any increase of ¹³⁷Cs activity concentrations. The ecological half-life for ¹³⁷Cs was estimated to be 8.0 and 8.4?years for chicken meat and eggs respectively. The correlation between ¹³⁷Cs in fallout and chicken meat as well as between ¹³⁷Cs in fallout and eggs is very good, the respective correlation coefficients being 0.79 and 0.72, indicating that fallout was the main source of ¹³⁷Cs contamination in both foodstuffs. The estimated effective doses received by adult members of the Croatian population due to the intake of radiocaesium by chicken meat and egg consumption for the overall observed period are very small, 2.0 and 0.6 µSv respectively. Therefore, chicken meat and chicken egg consumption was not a critical pathway for the transfer of radiocaesium to humans.     

Evaluation of transport and storage of 60Co, 134Cs, 137Cs and 65Zn by river sediments in the lower Susquehanna River

The Peach Bottom Atomic Power Station (PBAPS) has contributed measurable quantities of radioactivity to Conowingo Reservoir, an impoundment of the lower Susquehanna River. As part of an ongoing radiological assessment program, concentrations of plant-related radionuclides in sediments have been monitored in spring and fall since 1980. Mass balance estimates derived from grab samples of surface sediments (< 10 cm) indicate that less than 20% of reactor released (60)Co, (65)Zn, (134)Cs and (137)Cs is present in these sediments. Significant seasonal variations in radionuclide trapping efficiency by the reservoir are not apparent. Deep core samples (c. 200 cm) confirm that some, but not all, of this surface sediment radionuclide inventory remains within the reservoir-trapped in discrete locations by subsequent sediment accumulation. The remaining radionuclide mass, in dissolved or particle-associated form, appears to be transported downstream, through Conowingo Dam, to upper Chesapeake Bay. The detection of PBAPS-derived radionuclides in the sediments of upper Chesapeake Bay, primarily the Susquehanna Flats, confirms the transport of these radionuclides from the lower Susquehanna River.     

The influence of season and leaf age on concentrations of radiocaesium (137Cs), stable caesium (133Cs) and potassium in Agrostis capillaris

The transfer of radioactive caesium from soils to plants has been well researched. In contrast there is limited knowledge on natural stable 133Cs and its potential role as a predictor for radiocaesium behaviour. In a pot experiment with Agrostis capillaris close correlations were found between plant 137Cs and plant 133Cs concentrations (R2 90-96%). Season and leaf age had significant effects with concentrations increasing 10-30-fold between June and December. Simultaneously the plant concentrations of K, the nutrient analogue of Cs, decreased to around one third. In the soil the exchangeable fractions of K and 137Cs declined. No clear relationships were found between 137+133Cs in the plant and exchangeable K in the soil. However, at the end of the experiment the K content of the above-ground biomass was higher than the exchangeable pool in the soil, suggesting that depletion of soil K could be a key factor in the observed increase of plant 137+133Cs over time.     

137Cs determination and mutagenicity tests in wild Mus musculus domesticus before and after the Chernobyl accident

Wild rodents were collected alive in a suburban area to the north of Rome before, during, 6 months and 1 year after the Chernobyl accident. Radionuclide determinations to assess their content of (137)Cs and mutagenicity tests (bone-marrow micronucleus test and sperm abnormalities assay) were performed on the captured animals. The results obtained for the species Mus musculus domesticus (which was the rodent captured in highest numbers), compared with the results obtained before the fallout, showed an increase of both micronucleated polychromatic erythrocytes (MPCEs/1000 PCEs) and (137)Cs content during and after the fallout.     

The occurrence and bioavailability of radioactive 137Cs in small forest lakes in Southern Finland

Following the Chernobyl accident in late April 1986, central Finland was subjected to considerable radioactive fallout. The radioactive isotope of caesium, (137)Cs, was potentially the most harmful isotope in the fallout because of its long half-life (30 years). (137)Cs activities remained unexpectedly low within the biota (algae, zooplankton, aquatic moss, fish) of some humic forest lakes in southern Finland compared to the clear water lakes within the same district. This observation suggested that humic substances, by binding (137)Cs chemically, may reduce its bioavailability in lake water. Our laboratory experiments (throughflow systems; gel chromatography) demonstrated that binding of (137)Cs by humic substances was negligible in untreated lake waters; only when most of the alkali metals had been removed with an ion exchange resin was any binding of (137)Cs by low molecular humic fractions apparent. Instead, the concentrations of cations (especially potassium) were of overwhelming importance for the bioavailability of (137)Cs within the lacustrine ecosystems. The concentrations of (137)Cs within food chains are expected to stay at a high level for many years especially in lakes with long water renewal times.     

Determination and analysis of distribution coefficients of 137Cs in soils from Biscay (Spain)

The distribution coefficient of (137)Cs has been determined in 58 soils from 12 sampling points from Biscay by treating 10 g with 25 ml of an aqueous solution with an activity of 1765 Bq in the radionuclide, by shaking during 64 h and measuring the residual activity with a suitable detector. Soils were characterised by sampling depth, particle size analysis and the usual chemical parameters. Soils were thereafter treated to fix the chemical forms of (137)Cs speciation by successive extractions in order to determine fractions due to exchangeable, associated with carbonates, iron oxide and organic matter fractions, obtaining by difference the amount taken by the rest of the soil constituents. For this research, 16 soils from four points were selected from the previous samples. The greatest mean percentages of (137)Cs sorption were with the rest (69.93), exchangeable (13.17) and organic matter (12.54%) fractions. This paper includes also the calculation of partial distribution coefficients for chemical species as well as relations of distribution coefficients both among them and with soil parameters.     

Influence of major African dust intrusions on the 137Cs and 40K activities in the lower atmosphere at the Island of Tenerife

The influence of two intensive low-altitude atmospheric-dust intrusions on the activity levels of ¹³⁷Cs and ⁴⁰K as well as atmospheric particle matter (PM10) concentrations in the lower atmosphere of the Canary Islands are analysed here. These two events took place at the beginning of January 2002 and March 2004, respectively. 3D atmospheric back-trajectories indicated that the main source of dust material involved in the considered atmospheric intrusions came from NW Africa. A consequence of these dust intrusions was the major increase of PM10 concentrations in the lower atmosphere. Both episodes were characterised by having weekly averages of PM10 concentration surpassing 150 μg m⁻³, higher than the daily PM10 limit value established by the EC/1999/30 directive for PM10 from 2005. Similarly, during these two events, both ¹³⁷Cs and ⁴⁰K activities increased by a factor of 6 and 13 as well as 13 and 14, respectively, over the basal values calculated for each radionuclide and time period (0.59±0.02 and 0.88±0.07 μBq m⁻³ as well as 12±6 and 24±8 μBq m⁻³).     

Leaves of higher plants as biomonitors of radionuclides (137Cs, 40K, 210Pb and 7Be) in urban air

Leaves of linden (Tilia tomentosa L. and Tilia cordata Mill.) and horse chestnut (Aesculus hippocastanum L.) were analysed as biomonitors of radionuclides in urban air. Samples of soils, leaves and aerosols were collected in Belgrade, Serbia. Activities of ¹³⁷Cs, ⁴⁰K, ²¹⁰Pb and ⁷Be in the samples were measured on an HPGe detector by standard gamma spectrometry. “Soil-to-leaves” transfer factors were calculated. Student’s t test and linear Pearson correlation coefficients were used for statistical analysis. Differences in local conditions at the sampling sites were not significant, and the mechanisms of the radionuclides’ accumulation in both plant species are similar. Ceasium-137 was detected in some of the leaf samples only. Transfer factors for ¹³⁷Cs and ⁴⁰K were (0.03–0.08) and 1.3, respectively. The concentrations of ²¹⁰Pb and ⁷Be in leaves were higher in autumn than in spring, and there were some similarities in their seasonal patterns in leaves and in air. Weak to medium correlation was obtained for the ²¹⁰Pb and ⁷Be activities in leaves and aerosols. Large positive correlation was obtained for the ²¹⁰Pb activities in linden leaves and the mean activity in aerosols for the preceding months. Different primary modes of radionuclides accumulation in leaves were observed. Since large positive correlation was obtained for the ²¹⁰Pb activity in linden leaves and the mean in aerosols for the preceding months, mature linden leaves could be used as biomonitors of recent ²¹⁰Pb activity in air.     

Distribution coefficients (Kd) and desorption rates of 137Cs and 241Am in Black Sea sediments

The distribution coefficients (K_d) and desorption rates of ¹³⁷Cs and ²⁴¹Am radionuclides in bottom sediments at different locations in the Black Sea were studied under laboratory conditions. The K_d values were found to be 500 for ¹³⁷Cs and 3800 for ²⁴¹Am at the steady state and described exponential curves. Rapid uptake of the radionuclides occurred during the initial period and little accumulation happened after four days. The desorption rates for ¹³⁷Cs in different bottom sediments were best described by a three-component exponential model. The desorption half-times of ¹³⁷Cs ranged from 26 to 50 d at the slow components. However, the desorption rate of ²⁴¹Am described one component for all sediment samples and desorption half-time was found to be 75 d. In general, the results showed that the ²⁴¹Am radionuclide is more effectively transferred to bottom sediment and has longer turnover time than ¹³⁷Cs under Black Sea conditions.     

Analysis of the impact of various vertical release patterns on the atmospheric dispersion and total deposition of 137Cs from Chernobyl Nuclear Power Plant accident

Environmental Science and Pollution Research - The Chernobyl Nuclear Power Plant (NPP) catastrophe of 1986 has been a milestone in the use of nuclear power for energy generation. After the...     

Foliar leaching of 137Cs from Eriophorum vaginatum L., Scirpus caespitosus L. and Erica tetralix L

Evidence of extensive leaching losses of nutrients, particularly of K, suggest that loss of 137Cs by foliar leaching could be considerable and could stimulate further root uptake and redistribution of 137Cs in plants. This study investigated the foliar leaching of 137Cs from two deciduous graminoid species, Eriophorum vaginatum and Scirpus caespitosus and one evergreen shrub, Erica tetralix. Plants were labelled with 137Cs via the roots and subjected to a leaching treatment in August and November and changes in both leachate and plant 137Cs activity were determined. Leaching losses were significantly reduced in November compared with August in the deciduous species, but not in the evergreen E. tetralix. A reduction in the total activity of 137Cs of leached plants was observed not only in leaves but also in stems and roots in some instances, suggesting that 137Cs from these organs had been redistributed to replenish that lost by leaching from the leaves. The data suggest that leaching losses were greater from older and senescent leaves than from younger leaves of E. vaginatum. The extent to which this is an accurate representation of foliar leaching of field-grown plants by rainfall, and the likely fate of 137Cs lost by foliar leaching are discussed.     

Translocation studies of 137Cs and 90Sr in bean plants (Phaseolus vulgaris): simulation of fallout

In case of an accident at a nuclear power plant with liberation of radioactive material into the atmosphere, knowledge about the behavior of plant species when in contact with radionuclides is indispensable for safety reasons. The leaf-fruit translocation is an important route through which agricultural products are contaminated by radionuclides. To quantify the leaf-fruit translocation factors for 137Cs and 90Sr in common beans (Phaseolus vulgaris) an experiment was carried out in a greenhouse with a randomized block design. 137Cs activity was determined by gamma-ray spectrometry, while chemical separation followed by beta counting of 90Y was used for 90Sr determination. The model applied for translocation indicated functional dependence between the moment of tracer application and the physiological development of the bean plant. Translocation factors obtained for 137Cs and 90Sr were 0.16 and less than 0.005, respectively.     

Effective dose estimation and lifetime cancer mortality risk assessment from exposure to Chernobyl <Superscript>137</Superscript>Cs on the territory of Belgrade City and the region of Vojvodina,Serbia

Purpose  

The purpose of this paper is to determine the activity concentrations of radionuclide ¹³⁷Cs in soil samples on the territory of Belgrade and the province of Vojvodina. Also, the lifetime cancer mortality risk from external exposure during 1 year is assessed, and the effective dose is estimated.