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1.
210Pb具有百年时间尺度沉积计年的重要价值。210Pbex计年假设：沉积物是封闭系统；进入水体的210Pb能有效地转移到沉积物中并不发生沉积后迁移；非过剩210Pb与其母体226Ra保持平衡。210Pbex计年可用稳定输入通量-稳定沉积物堆积速率模式、常量初始浓度模式或恒定补给速率模式。沉积物柱芯必须保持原态并以0．5～1cm间隔分截；用相应层节226Ra校正。沉积物表层混合作用及222Rn的丢失可能导致顶部210Pbex异常。季节性缺氧湖泊沉积物顶部可能存在210Pb及210Po的再迁移。210Pb与137Cs两种计年方法原理上具有根本差别。210Pb，137Cs与沉积纹理方法对比是准确计年的重要保证。 相似文献
2.
William Sidle 《Environmental Geology》2009,57(2):377-388
Recent identification of elevated excess 210Pb (≤302.6 mBq L−1) and 137Cs (≤111.3 mBq L−1) activity in drinking water wells up to 20 m depth indicates some transport of airborne radionuclide fallout beyond soils
in the Shaker Village catchment, Maine. Estimated airborne mass loading 210Pbex fluxes of about 0.9 mBq m−3, canvass this headwater catchment and may be sufficient to pose risks to unprotected shallow wells. Inventories of 210Pbex and 137Cs in pond sediments indicate maximum median activities of 943 mBq g−1 and 40.0 mBq g−1, respectively. Calculated 210Pbex fluxes in the catchment soils range from 0.62–0.78 Bq cm−2 year−1 and yield a mean residence time of near 140 years. Measured 137Cs activity up to 51.1 mBq g−1 occurs in sediments at least to 5 m depth. Assumed particle transport in groundwater with apparent 85Kr ages less than 5 years BP (2005) may explain the correlation between these particle-reactive radionuclides and elevated
activity in some drinking water wells. 相似文献
3.
如同137Cs和210Pbex核尘埃,土壤和坝库沉积物中的孢粉也源于大气沉降,是否能用于侵蚀产沙的示踪研究?在陕北吴旗周湾水库采集了一些表层土壤和现代淤地坝、古代聚湫坝沉积泥沙的样品,尝试土地利用/覆被变化和侵蚀产沙的孢粉示踪研究。初步研究表明:草地表土孢粉丰富,平均浓度为26077粒/g;有33个科属的花粉,孢粉组合反映了当地以蒿属为主的半干旱温带草原植被;坡耕地表土的孢粉组合和草地一致,但孢粉平均浓度远低于草地,仅5844粒/g。坝库沉积剖面中,和137Cs核素一样,孢粉也富集于每一洪水沉积旋迴的上部层位,可用于沉积旋迴的区分。现代沉积旋迴的孢粉平均浓度,远低于草地和坡耕地表土,这表明草地和坡耕地土壤不是沉积泥沙的主要来源。古代沉积物的孢粉平均浓度高于现代沉积,表明流域内300年前的植被好于现代,或300年前沟谷地的相对产沙量低于现代。古代孢粉组合中十字花科花粉比例高达36·85%,明显高于现代的0·58%含量,这表明草地退化严重,十字花科植物比例急剧降低。孢粉示踪技术在植被环境恢复,沉积旋迴区分,和泥沙来源确定等方面具有一定的潜力,但应建立针对土地利用/覆被变化和侵蚀产沙研究的孢粉示踪技术方法。 相似文献
4.
Sediment cores were collected from deep-water areas of Lake Chenghai, China in June 1997. The vertical profile of 137Cs activity gives reliable geochronological results. The results also indicate that sediment accumulation rates in deep-water areas of Lake Chenghai were relatively constant in recent decades, averaging 0.43 g cm− 2 y− 1, despite a variable organic carbon influx. 210Pbeq (= 226Ra) activity was relatively constant also, with an average value of 54.3 ± 3.2 Bq kg− 1. Vertical profiles of 210Pbex (= 210Pbtotal − 226Ra) decreased exponentially, resulting in somewhat lower sediment accumulation rates (0.3 g cm− 2 y− 1). These lower rates are likely less reliable, as the relatively large fluctuations in 210Pbex activities correlate closely to the organic carbon (Corg) content of the sediments. For example, the vertical profile of 210Pbex activity displays peaks at mass depths of 3.7-4.7 g cm− 2 (10-12 cm) and 10-11 g cm− 2(25-28 cm), similar to the maxima in the vertical profile of Corg. This phenomenon must be related to the delivery of particulate organic matter (POM) from the water to the sediments, or to watershed soil erosion. Since the mean atomic ratios of Horg / Corg and Corg / Norg in Lake Chenghai sediments are 5.5 and 7.0, respectively, indicating that POM was predominantly derived from the remains of authigenic algae, this eliminates watershed erosion rates as a primary control on lake sedimentation rates as resolved by 210Pbex. Sedimentation fluxes (F(Corg)) of particulate organic carbon since 1970 varied between 60 to 160 g m− 2 y− 1, and appeared to closely influence variations in 210Pbex concentrations. For example, sedimentation fluxes of 210Pbex (F(210Pbex)) showed maxima in the years 1972-1974 and 1986-1989, likely reflecting historical variations of lake biological productivity or carbon preservation. 相似文献
5.
Single cores from two salt marshes in the United Kingdom located near different nuclear facilities were investigated to compare chronostratigraphic estimates derived from the natural radionuclide 210Pbexcess with estimates from the known times of introduction of artificial radionuclides to the environment. Both cores selected had clear visual indications of redox zonation, and evidence for diagenetic redox perturbation of the radionuclide records was also sought. In the core from Beaulieu Marsh on the south coast of England, the redox zonation was revealed by the profiles of the redox-sensitive elements Mn + I, Fe + P + As, and S, and the records of nuclear discharges were entirely contained within oxidized conditions in the upper 40 cm. The constant flux/constant sedimentation 210Pbexcess accumulation estimate was 76% of that derived from the 1963 fallout 137Cs level (0.35 vs. 0.46 g cm−2 yr−1 dry mass), but the constant flux 210Pbexcess method indicated that accumulation rates were lower at Beaulieu before ∼1950. On any timescale, 137Cs appears earlier in the sediment record than its introduction to the environment, but although downward diffusion of 137Cs relative to 241Am has clearly occurred, the 137Cs peak still appeared in place and there was negligible penetration of 137Cs into underlying reduced conditions. This core also contained a peak of the 60Co discharges from either or both the Winfrith and La Hague nuclear plants that peaked in 1980 and 1984, respectively. The sediments in the core from Wyre Marsh on the eastern coast of the Irish Sea had accumulated more rapidly than those at Beaulieu, and in this case the redox zonation could be established only from Mn and S profiles. Here, the constant initial activity 210Pbexcess accumulation rate estimate was 125% of that derived from the 137Cs peak correlated with the 1975 Sellafield discharge maximum (0.79 vs. 0.64 g cm−2 yr−1). Sellafield discharge 137Cs swamps fallout or Chernobyl 137Cs signals in this core, but the 137Cs and 241Am sediment records are well separated and remain consistent with the slightly different discharge patterns over time. This is so despite the fact that the maximum activity levels of both isotopes are now located well into reducing conditions out of which Mn must have migrated. The 210Pb profile appeared similarly unaffected by the oxidized/reduced boundary in this case. This core was too short to define the limits of any downward 137Cs migration. 210Pbexcess accumulation rate estimates for salt marshes should be viewed with some caution because of the steady-state assumptions inherent in all 210Pbexcess methods and the potential for fluctuating accumulation conditions and open system behavior in salt marshes. 相似文献
6.
W. Dyck 《Journal of Geochemical Exploration》1984,20(1):85-92
Vertical profiles of 210Po in soils near the Midwest uranium deposit and an associated surficial radioactive sandstone boulder train in northern Saskatchewan show a high 210Po background in air-dried forest litter (24 pCi/g) and Ah horizon soil (11 pCi/g) relative to lower soil horizons (<1 pCi/g). These high levels mask the 210Po signal from the radioactive boulders in the near-surface soil horizons. Only in the Bf and C horizons can the existence of the radioactive boulders be inferred from 210Po determinations. For comparative purposes profiles for 226Ra, U, Ni, and other trace elements are also presented.Escape of most of the Rn from near surface soils into the atmosphere, homogenization and decay of Rn, and precipitation of decay products back onto surface soils satisfactorily explain the field observations discussed here.Compared to the highly anomalous 222Rn signal in soil gases over this boulder train the 210Po contrast is very weak and is of little use for prospecting for this type of boulder train. The relatively high 210Po background in surficial materials relative to lower soil horizons dictates that great care be taken with the 210Po method; the deepest possible horizons should be sampled. 相似文献
7.
210Po and 210Pb measurements of soils delineated uranium anomalies at three out of four test sites in Ontario, Canada. Measurements were made of 210Po in solutions produced by both complete digestion and partial leaching of soil samples. Direct plating of 210Po onto metal plates was followed by measuring the alpha activity. Subsequent plating of 210Po in-grown from 210Pb in solution several months later confirmed the anomalies.The 210Po and 210Pb anomalies at three of the test sites coincided with 226Ra and 222Rn anomalies. Samples from the fourth uranium occurrence associated with a known 222Rn anomaly failed to show either a 226Ra anomaly on the one hand, or 210Po or 210Pb anomalies on the other. This suggests that the 210Po and 210Pb anomalies were probably produced by the decay of 226Ra contained within secondary dispersion haloes.Although anomalies due to the 210Po and 210Pb products of 222Rn have now been documented, prospecting methods based on their use as direct tracers of the migration paths of 222Rn require much further development. 相似文献
8.
210Po and 210Pb measurements of soils delineated uranium anomalies at three out of four test sites in Ontario, Canada. Measurements were made of 210Po in solutions produced by both complete digestion and partial leaching of soil samples. Direct plating of 210Po onto metal plates was followed by measuring the alpha activity. Subsequent plating of 210Po in-grown from 210Pb in solution several months later confirmed the anomalies.The 210Po and 210Pb anomalies at three of the test sites coincided with 226Ra and 222Rn anomalies. Samples from the fourth uranium occurrence associated with a known 222Rn anomaly failed to show either a 226Ra anomaly on the one hand, or 210Po or 210Pb anomalies on the other. This suggests that the 210Po and 210Pb anomalies were probably produced by the decay of 226Ra contained within secondary dispersion haloes.Although anomalies due to the 210Po and 210Pb products of 222Rn have now been documented, prospecting methods based on their use as direct tracers of the migration paths of 222Rn require much further development. 相似文献
9.
Characterizing the dynamics of fluvial sediment sources over space and time is often critical in identifying human impacts on fluvial systems. Upland interfluve and subsoil sources of suspended sediment at Loco Bayou, Texas, were distinguished using 226Ra/232Th, 226Ra/230Th and, 228Ra/232Th. Source contributions were apportioned at three stations during within-bank and flood flows. 137Cs and 210Pbxs (excess 210Pb) were used to determine floodplain sedimentation; suspended sediment 210Pbxs/137Cs data mirrored results of Ra/Th, showing dominance of subsoil sources during within-bank flows, changing to interfluve sources during flood. This trend corresponds spatially to influx of sediment from ephemeral tributaries, reflecting mobilization of stored interfluvial sediments during flood stage. Upper basin sedimentation was similar but markedly less at the lowermost station. These results indicate (1) modified ephemeral tributaries store sediment derived from sheet wash, discharging them during flood, and (2) southernmost Loco Bayou is episodically re-worked, resulting in significantly reduced local rates of sedimentation. 相似文献
10.
Fu WANG Hong WANG Jianfen LI Yandong PEI Changfu FAN Lizhu TIAN Zhiwen SHANG Meiyu SONG Yan GENG 《Frontiers of Earth Science》2008,2(3):276-282
The representative 210Pb and 137Cs age-depth profiles were selected from more than 100 sites in the Circum Bohai Sea (CBS) coastal region to examine the sedimentation
rates and associated environmental changes. There are three unique 210Pbexc distribution patterns: 1) ideal-decaying type, representing relatively constant sediment supply and quieter environmental
setting; 2) wiggling type, but with approximately equivalent amplitude, representing coarser sediments and associated stronger
flow current environment; and 3) episodic-eventinfluencing type, each representing typhoon storm-influenced depositional environment.
Our results also show that there is a lower sedimentation rate (ca. 0.1 cm/a) in the coastal lowlands, a higher sedimentation
rate (ca. 0.5–3 cm/a) in the intertidal flat and an intermediate rate of ca. 0.58 cm/a in the subtidal zone near the Huanghua
Harbor. The interbedded silt layer occurring in the core sediment reveals lower 210Pb activities, indicating a discontinuous sedimentation mostly due to typhoon events which dwarfs against 210Pb and 137Cs applicability. Overall, the 210Pb and 137Cs measurements of the present study provide physical insight into the evaluation of the coastal-marine ecological environment
and associated management. 相似文献
11.
Reliable dating is an essential element of palaeoseismological studies, yet whilst a suite of geochronological methods can now provide late Quaternary age control it remains very difficult to date modern events (i.e., those occurring within the last 150 years). This is significant because the starting point for many palaeoseismological investigations is a modern surface-rupturing event, whose geological effects need to be disentangled in trench stratigraphies from palaeoseismic ruptures. Two dating methods which, in combination, can provide robust dating control in recently deposited sediments are the 210Pb and 137Cs dating methods. Here, we test the applicability of using 210Pb and 137Cs to date colluvial sediments exposed in three trenches excavated across an earthquake fault—the Eliki fault, Gulf of Corinth, Greece—which ruptured in an earthquake in 1861. The 210Pb and 137Cs profiles observed in these colluvial sequences are relatively erratic due to the mixed nature of the sediments, i.e., their deposition in an environment where the supply of slope sediments is driven by seasonal rainfall, causing non-uniform sediment accretion and sediment reworking. In one trench, however, 210Pb dating, corroborated by 137Cs dating, indicates that a proposed post-1861 surface colluvial unit has been deposited over the period 1950 AD–present (at a rate of ca. 9 mm/year), and overlies a significantly older unit (>120 years old). The dating control provided here by 210Pb and 137Cs dating corroborates the published interpretation of the trench stratigraphy, and refines the 14C-based estimated dates for the upper unit. At two other trenches 210Pb and 137Cs dating only provided minimum ages (based on the presence or absence of 210Pbexcess and 137Cs). Such approximate ages, however, may still useful in corroborating interpretations made using the trench stratigraphy, or, at sites which have long earthquake recurrence intervals, determining which earthquake event was responsible for a particular bed offset. 相似文献
12.
Ryoko Fujiyoshi Takayuki Yamaguchi Naoki Takekoshi Kazumasa Okamoto Takashi Sumiyoshi Ivan Kobal Janja Vaupotič 《Central European Journal of Geosciences》2011,3(3):291-301
Depth distribution profiles of environmental radionuclides (137Cs and 210Pb) have been investigated in soil to elucidate the underlying environment of semi-natural temperate deciduous and/or coniferous forest soils in Slovenia (?irovski vrh, Idrija, Ko?evski Rog, Pohorie, Gori?nica and Rakitna). Surface enrichment of both nuclides was observed at all the sites investigated in this study, suggesting that the soils had undergone little natural or anthropogenic disturbance for at least the last several decades. Apparent annual burial rates of 137Cs (0.1–0.2 cm y??1) were estimated to be about 1.3 times higher than those of 210Pb at individual sites of different lithology, which suggests strong affinity of 210Pb to soil organic matter. Variability of the vertical distribution profiles of these nuclides depends not only on “in situ” pedology but also on geographical and meteorological conditions, especially precipitation and wind direction. 相似文献
13.
《Physics and Chemistry of the Earth, Part A: Solid Earth and Geodesy》1999,24(10):881-885
The redistribution of Chernobyl 137Cs within a small drainage basin was studied in the Lokna river basin, Tula region, Central Russia. Sheet erosion on the cultivated part of basin is the main reason for 137Cs horizontal migration. However there is no statistically significant 137Cs redistribution within cultivated field because of relatively low erosion rates. The valley bottom is the main sink of 137Cs, where 73–84% eroded soil is stored. The resulting 137Cs level in the valley bottom is 1.5–2 times that of the initial 137Cs fallout. 相似文献
14.
This study uses radiometric analysis (210Pb and 137Cs) of short sediment cores with high-resolution sampling (1-cm interval) to trace sedimentation rates in the Nile Delta lagoons,
particularly since completion of the Aswan High Dam in 1964. A declining trend in 210Pbex as calculated by the CIC model is clearly identified in about 10 cm of the upper-core sediments from the lagoons of Manzala
and Edku, accompanied by two spikes of 137Cs in cores from the lagoons of Burullus and Edku. These findings illustrate average post-dam sedimentation rates ranging
from 0.22 to 0.27 cm a−1 in the lagoons, in contrast with those found previously based on low-resolution sampling. The lower sedimentation rates in
the lagoons are a consequence of a dramatic reduction in riverine sediment load to the coastal area as a result of the damming.
Although widespread erosion occurs along the open estuarine coast, the lagoon setting remains calmer than before due to coastal
diking and freshwater regulation in the delta plain in the past decades. This provides the possibility of continuously preserved
radiometric records in the less-bioturbated lagoon sediments. Dating individual layers using the CRS model has revealed increasing
sedimentation rates in Manzala and Burullus since the 1980s, which can largely be explained as a consequence of the reduction
in lagoon area due to intensifying reclamation. The post-dam sedimentation in the shrinking lagoons may have some adverse
ecological consequences due to finer sediment’s affinity with pollutants. These findings would shed light on the environmental
conservation and socioeconomic development in the Nile Delta region. 相似文献
15.
J.Kirk Cochran 《Geochimica et cosmochimica acta》1985,49(5):1195-1210
Particle mixing rates (DB) calculated from excess 210Pb gradients in sediments of the east equatorial Pacific range from 0.04 to 0.5 cm2/y, with variation of a factor of 3–4 at a single site. Diffusion of the 236Ra daughter 222Rn may affect 210Pb distributions under conditions of slow mixing and low 210Pb flux to the seafloor, as shown by a siliceous ooze-clay core which contained the fallout radionuclides 239,240Pu and 137Cs but no excess 210Pb (relative to 226Ra). There is no clear relationship between 210Pbderived mixing rates and sediment type, accumulation rate or organic carbon flux to the sediments. Comparison of 210Pb mixing rates with those calculated from 239,240Pu and 137Cs distributions reveals better agreement for a pulse input of the fallout radionuclides (DB = 0.03?0.4 cm2/y) than for continuous input at a constant rate (DB = 0.1?1.6 cm2/y), although the Pu and 137Cs data are better fit by the latter model. The agreement may be fortuitous because 239,240Pu and 137Cs appear significantly deeper than 210Pb in at least one core. Tracer separation could be caused by particle size-selective mixing by the benthic fauna or by chemical mobilization. If the fallout radionuclides are scavenged from surface waters by large, organic-rich particles such as fecal pellets, their release and migration may result from decomposition of the carrier in surface sediments. Either a relatively unreactive form of Pu (e.g. oxidized Pu) has been released by this process or a one-dimensional model is inadequate to explain its observed penetration into the sediments. Activity ratios of in the sediments decrease with increasing north latitude, and the trend reflects higher fluxes of 239,240Pu near the weapons test site at Christmas Island (2°N). The ratios and fluxes to the sediment (assuming constant input) at the siliceous ooze-red clay site are consistent with published sediment trap data from a nearby site. Thus if fallout radionuclide fluxes to the sea floor were higher in the past, both 239,240Pu and 137Cs have been released from sinking particles. 相似文献
16.
本文介绍了一种新的野外测222Rn法——液体闪烁测222Rn法。该法取样时间短,操作简单,灵敏度高,重复性好,成本低廉,并能有效地克服钍射气的干扰。野外应用取得了较好的效果。 相似文献
17.
Groundwater surveys were performed by detailed(around 300 sites) grid-analysis of water temperature, pH, redox potential, electrical conductivity, 222Rn, alkalinity and by calculating the pCO2, throughout the Ciampino and Marino towns in the Alban Hills quiescent volcano (Central Italy). Following several episodes of dangerous CO2 exhalation from soils during the last 20 years and earlier ashistorically recorded, the work aimed at assessing the Natural Gas Hazard (NGH) including the indoor-Rn hazard. The NGH was defined as the probability of an area to become a site of poisonous peri-volcanic gas exhalations from soils to the lower atmosphere (comprising buildings). CO2 was found to be a ``carrier' for the other poisonous minor and in trace components (HsS, CH4, 222Rn, etc.). This assessment was performed by extrapolating in the aquifer CO2 and 222Rn conditions, and discriminating sectors where future CO2 flux in soils as well as indoor-Rn measurements have to be noted. A preliminary indoor-Rn survey was performed at about 200 sites. The highest values were found in the highest pCO2 and high 222Rn values in groundwater. This indicates convection and enhanced permeability in certain sectors of the main aquifer, i.e., along the bordering faults and inside the gas-trap of the Ciampino Horst., where ``continuous gas-phase micro-macro seepage mechanism' is invoked to explain the high peri-volcanic gases flux. 相似文献
18.
The principal relationships between radon (222Rn and 220Rn) exhalation intensities and the morpho-dynamic elements of humid tropical landscapes have been established and analyzed with the objective of elaborating Rn exhalation models, which can be used on the scale of small habitational nuclei. The current radioactive processes of generation, emanation and migration of Rn, in relation to its exhalation rates on a landscape slope of granitic rock having normal U and Th contents, were correlated with the latosol-podzolic soil association developed as a product of supergene processes during geological and pedological times and also with the water regime of an overlying phreatic aquifer. This approach, encompassing pedogeochemical models of radionuclide dispersion linked to soil systems and surface geochemistry, was framed within a tridimensional, interdisciplinary and systemic focus, using concepts of nuclear physics, climate and hydrogeology. The characteristic signatures of elementary landscapes include (1) different landforms, namely eluvial, transeluvial and superaqual, (2) residual soils having varying types, thicknesses and perma-porosities and (3) radioanomalies corresponding to different U and Th concentrations, secondary hosting minerals and also to different pedological ages. Considering these factors and their spatial relationships and on the basis of moisture content of soils, it is postulated that the highest Rn exhalation rates, especially of 222Rn, are confined to superaqual and transeluvial landscapes. In an eluvial landscape, the Rn fluxes are found to be less important even though gamma anomalies exist mainly due to the presence of resistant minerals containing U and Th. In short, the products of supergene alteration organized in a sloping system can exhibit Rn exhaling intensities higher than that measured on unaltered subjacent rock. Hence, the understanding of U, Th, Ra and Rn behavior on a surface environment is fundamental for the formulation of prognostic Rn exhalation models associated with the elementary humid tropical landscapes. Further, the pedogeochemical information provides important clues supplementing the lithostructural data for delineating preferential sites of Rn fluxes especially on scales compatible to small habitational nuclei or unitary dwellings. 相似文献
19.
Laboratory time-scale experiments were conducted on Carboniferous Limestone gravels from the Mendip Hills area, England, with the purpose of evaluating the release of222Rn to the water phase. The specific surface areas of the samples were 4.14 and 1.69 cm2 g−1 , which provided, respectively, values of 50.6 and 12.7 pCi for the released Rn. These results allowed the calculation of the emanation coefficient of this rock matrix with respect to the release of Rn, where completely different values corresponding to 23% and 6% were found, suggesting that the extent to which grain boundaries or imperfections in aggregates of micro-crystals of calcite intersect the particle surface certainly affects the Rn release. They also permitted the evaluation of models for the generation of Rn in rocks and transfer to water, in order to interpret the radioactivity due to this gas in groundwaters from the karstic aquifer of the Mendip Hills area, where the calculated activities in groundwater based on the values of 23% and 6% for the emanation coefficient were about 51 and 15 times higher than actually measured in groundwater. Therefore, the emanation coefficient in nature is considerably smaller than in the lab experiment, and another factork (0 < k < 1) may be introduced into the equations related to the modelling, with the aim of adjusting the theoretical-practical results. 相似文献
20.
I. Vukašinović D. Todorović Lj. Životić L. Kaluđerović A. Đorđević 《International Journal of Environmental Science and Technology》2018,15(5):1049-1060
This study of environmental radioactivity was carried out in the soils of an urban area. Naturally occurring gamma-emitting radionuclides and man-made 137Cs were found in the soil profiles collected from four parks in the central Belgrade city area and the soil layer was examined every 10 cm and to a depth of 50 cm. Radioisotope activity concentrations (Bq kg?1) in the samples of urban soil using the gamma-ray spectrometry method were in the range of 14–46 for 238U, 33–50 for 226Ra, 29–63 for 210Pb, 1.2–3.4 for 235U, 28–50 for 232Th, 424–576 for 40K and 0.7–35.8 for 137Cs. Some of the basic physicochemical soil properties (pH, organic matter content, calcium-carbonate content, particle size distribution) were determined to investigate the impact on the vertical distribution of radionuclides. The results of this investigation showed that variations of activity concentration ratios of radionuclides that belong to the same (238U/226Ra) or different radioactive series (232Th/226Ra; 235U/238U), including 210Pb/137Cs ratios could well be explained by the properties of the soil. Alkaline pH reaction, the accumulation of organic matter in the uppermost and of carbonates in the deepest layers of urban soil had an effect on 238U/226Ra, and 210Pb/137Cs activity concentration ratio values, while 232Th/226Ra and partially 235U/238U ratios were associated with the particle sizes vertical distribution. A study of radionuclides in the samples of leaves of two deciduous tree species common for these parks was also conducted and 210Pb and 40K were found concentrated in leaves rather than other investigated radionuclides. 相似文献