Determination of Cs in the water system of a pre-Alpine lake

The aim of this study was to measure the ¹³⁷Cs activity derived from the Chernobyl accident in the water system of Lake Wallersee, a pre-Alpine lake in Austria within an area highly contaminated by the Chernobyl fallout.     

Long-term investigation of anthropogenic and naturally occurring radionuclides at reference sites in western Sweden

In case of an accidental release of radioactive substances into the environment, it is important to quickly and reliably estimate the radiation dose received by people in the affected area, and to determine the extent of the contamination. Measurements of the extent of the release and the subsequent contamination can be facilitated if there are predetermined reference sampling sites with known background radiation and inventory of radionuclides. Since 1996, 34 reference sites for soil sampling, field gamma, and intensimeter measurements have been established in western Sweden. Time series data for dose rates and radioisotope inventory have been collected at these sites, allowing for the investigation of changes in these parameters over time. The mass activity densities for the uranium and thorium series elements varied approximately between 10 and 50 Bq/kg and between 10 and 40 Bq/kg, respectively. The mass activity density of ⁴⁰K was approximately in the range 300–800 Bq/kg. The radiation exposure due to ¹³⁷Cs was rather small in this area. The dose rates calculated from in situ measurement data showed that the contribution to the total dose rate was almost entirely due to naturally occurring radionuclides. The measured dose rate was about twice as high as the calculated rate, even after subtracting the contribution from cosmic radiation. This may be explained by the fact that intensimeters generally are calibrated to measure the quantity ambient dose equivalent, which should not underestimate the effective dose.     

Recent atmospheric lead deposition recorded in an ombrotrophic peat bog of Great Hinggan Mountains, Northeast China, from Pb and Cs dating

Radioactive markers are useful in dating lead deposition patterns from industrialization in peat archive. Peat cores were collected in an ombrotrophic peat bog in the Great Hinggan Mountains in Northeast China in September 2008 and dated using ²¹⁰Pb and ¹³⁷Cs radiometric techniques. The mosses in both cores were examined systematically for dry bulk density, water and ash content. Lead also was measured using atomic emission spectroscopy with inductively coupled plasma (ICP-AES). Both patterned peat profiles were preserved well without evident anthropogenic disturbance. Unsupported ²¹⁰Pb and ¹³⁷Cs decreased with the depth in both of the two sample cores. The ²¹⁰Pb chronologies were established using the constant rate of supply model (CRS) and are in good agreement with the ¹³⁷Cs time marker. Recent atmospheric ²¹⁰Pb flux in Great Hinggan Mountains peat bog was estimated to be 337 Bq m⁻² y⁻¹, which is consistent with published data for the region. Lead deposition rate in this region was also derived from these two peat cores and ranged from 24.6 to 55.8 mg m⁻² y⁻¹ with a range of Pb concentration of 14-262 μg g⁻¹. The Pb deposition patterns were consistent with increasing industrialization over the last 135-170 y, with a peak of production and coal burning in the last 50 y in Northeast China. This work presents a first estimation of atmospheric Pb deposition rate in peatlands in China and suggests an increasing trend of environmental pollution due to anthropogenic contaminants in the atmosphere. More attention should be paid to current local pollution problems, and society should take actions to seek a balance between economic development and environmental protection.     

大亚湾沉积物中137Cs纵向迁移研究

鉴于海洋沉积物是^137Cs在海域内迁移的最终归宿．建立了沉积物中污染物纵向迁移分布的定量模型，在机理分析中充分考虑了海水-表层沉积物界面上通过沉降、扩散、吸附-解吸等作用完成的物质传输，并对大亚湾内4个监测点底质芯样中^137Cs活度进行了模拟分析，对未来底质中^137Cs的富集趋势进行了预测。     

Retention of 137cesium in acid sulphate soils of South Central Thailand

Adsorption and desorption of ¹³⁷Cs by acid sulphate soils from the Nakhon Nayok province, South Central Plain of Thailand located near the Ongkarak Nuclear Research Center (ONRC) were investigated using a batch equilibration technique. The influence of added limestone (12 and 18 tons ha^?1) on ¹³⁷Cs adsorption–desorption was studied. Based on Freundlich isotherms, both adsorption and desorption of ¹³⁷Cs were nonlinear. A large portion (98.26–99.97%) of added ¹³⁷Cs (3.7?×?10³?7.03?×?10⁵ Bq l^?1) was sorbed by the soils with or without added lime. The higher lime treatments, however, favoured stronger adsorption of ¹³⁷Cs as compared with soil with no lime, which was supported by higher K _ads values. The addition of lime, the cation exchange capacity and pH of the soil increased and hence favoured the stronger adsorption of ¹³⁷Cs. Acid sulphate soils with a high clay content, medium to high organic matter, high CEC, and predominant clay types consisting of a mixture of illite, kaolinite, and montmorillonite were the main soil factors contributing to the high ¹³⁷Cs adsorption capacity. Competing cations such as NH₄ ⁺, K⁺, Na⁺, Ca²⁺, and Mg²⁺ had little influence on ¹³⁷Cs adsorption as compared with liming, where a significant positive correlation between K _ads and soil pH was observed. The ¹³⁷Cs adsorption–desorption characteristics of the acid sulphate soils studied exhibited a very strong irreversible sorption pattern. Only a small portion (0.09–0.58%) of ¹³⁷Cs adsorbed at the highest added initial ¹³⁷Cs concentration was desorbed by four successive soil extractions. Results clearly demonstrated that Nakhon Nayok province acid sulphate soils have a high ¹³⁷Cs adsorption capacity, which limits the ¹³⁷Cs bioavailability.     

The Input and Transmission of Fallout Radionuclides Through Redó, a High Mountain Lake in the Spanish Pyrenees

Fallout radionuclides have increasing value as tracers of pathways for pollutant transport through catchment/lake systems, in addition to their more traditional role in dating sediment records. The objectivesof this study, carried out within the EU MOLAR project, were tomeasure atmospheric fluxes of fallout ²¹⁰Pb, ¹³⁷Cs and ⁷Be at Redó, to establish mass balances for theseradionuclides, and test and validate models of pollutant transport through the lake and its catchment. This was achieved by comparing measured fluxes and concentrations in the water column with theoretical estimates using simple compartment models. Several interesting points emerged. Differences betweensoil core and rainwater measurements suggest that Saharan dust may be an important source of fallout ²¹⁰Pb. Fluxes throughthe water column had a clear seasonal trend reflecting winter icecover. Significant concentrations of ¹³⁷Cs are still presentin the water column, due to continued inputs from the catchment and/or remobilisation from the bottom sediments.     

C, δC and total C content in soils around a Brazilian PWR nuclear power plant

Nuclear power plants release ¹⁴C during routine operation mainly as airborne gaseous effluents. Because of the long half-life (5730 years) and biological importance of this radionuclide (it is incorporated in plant tissue by photosynthesis), several countries have monitoring programs in order to quantify and control these emissions. This paper compares the activity of ¹⁴C in soils taken within 1 km from a Brazilian nuclear power plant with soils taken within a reference area located 50 km away from the reactor site. Analyses of total carbon, δ¹³C and ¹³⁷Cs were also performed in order to understand the local soil dynamics. Except for one of the profiles, the isotopic composition of soil organic carbon reflected the actual forest vegetation present in both areas. The ¹³⁷Cs data show that the soils from the base of hills are probably allocthonous.     

Heavy Metals and Radiochemical Analyses in the Sediments of the Rapallo Harbour

To assess the natural and anthropogenic radiocontamination, sediment samples were collected in the Tigullio Gulf (Ligurian Sea). the results presented here indicate a significant Cs-137 contamination (about 20 Bqkg^-1 dry weight) while concentrations of “primordial” natural radioisotopes were similar to those detected in other coastal areas. Gross sedimentation rates, determined through measurements of Be-7 concentrations, were at about 4-5 cm in the last 6 months. Natural and artificial radioactivity concentrations have been compared with data obtained in other Mediterranean areas. Heavy metals (Cu, Cr, Mn, Ni, Zn, Pb, Cd, Hg) concentrations were also determined inside the bay. Most elements displayed quite constant concentrations through the sediment core, except for copper which had showed highest concentrations in the top 16 cm of the sediment.     

Using Fallout Lead-210 Measurements to Estimate Soil Erosion in Three Small Catchments in Southern Italy

Soil erosion and associated off-site environmental impacts have attracted increasing attention in recent decades, and there is a growing need for reliable information on rates of soil loss. The potential for using ¹³⁷Cs fallout to quantify rates and patterns of soil redistribution over medium-term timescales (ca. 45 years) has been successfully demonstrated in a wide range of environments around the world. The similar behaviour of fallout ²¹⁰Pb in soils offers potential for its use as an alternative to ¹³⁷Cs, in areas where ¹³⁷Cs inventories are low or are complicated by additional fallout from the Chernobyl accident. There have, however, to date been few attempts to validate the use of fallout ²¹⁰Pb measurements for assessing erosion rates. This paper reports an attempt to explore the use of fallout ²¹⁰Pb to estimate rates of water-induced soil erosion on uncultivated land. It focuses on three small forest/rangeland catchments located in Calabria, southern Italy, for which measurements of sediment output are available. Comparison of the estimates of net soil loss from the catchments derived from ²¹⁰Pb measurements with the measured sediment output, confirmed the validity of the ²¹⁰Pb approach. The soil redistribution rates estimated using ²¹⁰Pb measurements were also consistent with equivalent estimates obtained for the same study catchments using ¹³⁷Cs measurements.     

90Sr、137Cs在某种包气带土壤中的迁移研究

本文叙述了放射性废物中具有代表性的裂变核素^90Sr、^137Cs在某种包气带土壤中的迁移情况研究。使用小型土柱的氚水淋洗实验研究土壤水力学性质，最后进行大型土柱实验研究核素在该包气带土壤中的迁移，并对实验情况进行了数学模拟。用该土壤原状土进行小型土柱的氚水淋洗试验，测得了土壤的水力弥散度为0．32cm，土壤有效孔隙度为0．35。经过290天的大型柱迁移试验表明，土壤对^90Sr的阻滞系数为220．4，在模拟实际降雨量的情况下，^90Sr的平均迁移速度为0．63cm/y，^137Cs在大型柱试验中没有明显迁移。数值模拟^90Sr、^137Cs迁移，得出经过上述大型柱试验相同的条件下，^90Sr、^137Cs迁移的峰位置基本和大型柱试验结果相同。