Transport of symmetric mass region fission products at the Oklo natural reactors

The isotopic composition of Pd, Ag, Cd and Te has been measured by solid source mass spectrometry for four samples from reactor zones 2, 3–4, 5–6 and 7, and from four host rock samples external to the reactor zones from the Oklo mine site. The concentrations of these elements have also been determined in the eight samples using the stable isotope dilution technique. Cumulative fission yields have been derived from the reactor zone samples after correcting where necessary for the terrestrial component of the element concerned.It has been shown that fission-produced Pd and Te are retained almost in their entirety in the uraninite reactor zone samples, whereas a significant fraction of fission-produced Ag and Cd have migrated from the reactor zones. Fission product Cd is observed in the host rock samples, whereas no strong evidence of fission-produced Ag could be found. Thus the fission-produced Ag which has migrated from the reactor zones has not been retained in the four host rock samples analysed, although the presence of fission product Ag may be masked by the presence of natural Ag. It is possible that the fission product Ag has been retained in the Oklo mine-site, and further host rock samples will be studied to evaluate this possibility. The implications of these results to the storage of radioactive wastes in natural geological repositories is discussed.     

Gamma emitting fission products in surface sediments of the Ravenglass estuary

The occurrence of some fission products from the Sellafield (formerly Windscale) nuclear fuel reprocessing facility has been determined for surface sediments from forty locations in the Ravenglass estuary, North-west England. The influence of the silt-sized fraction in the sediments on the geographic distribution of ¹³⁷Cs is clearly important, and to a lesser extent also influences the distributions of ¹⁰⁶Ru, ${}^{134}\text{Cs}\text{+}{}^{95}\text{Zr}\text{Nb}$ and ¹⁴⁴Ce. The data are compared with recently published results reported by the Ministry of Agriculture, Fisheries and Food for a monitoring site in this estuary.     

Heavy rare gases from Rabbit Lake (Canada) and the Oklo mine (Gabon): natural spontaneous chain reactions in old uranium deposits

Xenon isotopic studies confirm natural spontaneous chain reactions at the Oklo mine site (Republic of Gabon) with an integrated neutron flux of approximately 4 × 10²⁰n/cm² and a duration between 14,000 and 70,000 years. Similar studies for the Rabbit Lake deposit (Saskatchewan), a slightly younger site with some evidence of continued geologic activity, shows no evidence of self-supporting reactions.     

强地震附近电阻率对称四极观测的探测深度

针对我国地震监测预报中固定地点和固定观测装置及参数的视电阻率观测,给出了半空间倾斜各向异性介质中电阻率对称四极观测的理论探测深度,研究了地震前兆信息的检测深度问题,得到：(1)在强地震、孕震晚期阶段,在震中区及附近可检测到地壳近地表较深部介质的电阻率变化,其深度大于或远大于均匀介质之;(2)震级、震中距、观测方向不同或在不同的孕震阶段,探测深度存在差异,甚至存在大的差异,且是动态变化的.并依据理论探测深度讨论了地震视电阻率前兆变化的复杂性、地电台址电性条件等问题.     

Permittivity in the microwave region of some natural minerals

The permittivity measured at a frequency of 10 GHz normalized to constant density is the same within the experimental error for talc, baryte and dolomite. In the case of clay and kaolin, it is about 10% higher. This is attributed to the high content of Al₂O₃ (30–40%) in them, which interpretation is proved by experiment.     

Oil spill treatment products approval: the UK approach and potential application to the Gulf region

The environmental threat from oil spills remains significant across the globe and particularly in regions of high oil production and transport such as the Gulf. The ultimate damage caused can be limited by mitigation actions that responders deploy. The responsible and appropriate use of oil spill treatment products (e.g. dispersants, sorbents etc.) can offer response options that can result in substantial net environmental benefit. However, the approval and choice of what products to use needs careful consideration. The United Kingdom has had in place a statutory approval scheme for oil spill treatment products for 30 years. It is based on measures of efficiency and environmental acceptability. Two toxicity tests form an integral part of the assessment, the Sea test and the Rocky Shore test, and work on the premise that approved products will not make the situation significantly worse when added to spilled oil. This paper outlines the UK approach and how its rationale might be applied to the approval of products specific for the Gulf region. Issues such as species choice, higher temperatures and salinity and regional environmental conditions are considered.     

On fission and the devolatilization of a moon of fission origin

Observations of solar-type spectroscopic binary stars show that most of these objects were formed by rotational fission. By analogy, this empirical confirmation of the fission process is used to support the fission origin of the moon.The depletion of the volatile elements in the moon is explained as being due to their preferential evaporation from the initially hot (2000–4000°C) moon into an early primitive atmosphere. This atmosphere was simultaneously lost from the moon via transfer through theL₁ point and captured by the earth.     

A comparison of concentrations of fission products,radon 222, and cloud condensation nuclei over the North Atlantic

The concentrations of airborne fission products were observed to be air mass dependent during a cruise of the USNSHayes from Norfolk, Va to Athens, Greece in May–June 1977. Minimum concentrations of fission products, radon, and CCN (cloud condensation nuclei) were measured in maritime air which had previously transited northern North America. Higher fission products, radon, and CCN concentrations were measured in recent, continental air traceable to mid North America or central Europe. These data are consistent with either entrainment by strong winds of previously precipitated fission products (the continental effect) or greater transfer of fission products from the stratosphere to low levels by tropospheric folding.     

华北地区天然地震震相特征研究

本文主要分析了华北地区区域地震中6种常规震相(Pg、PmP、Pn、Sg、SmS、Sn)的基本特征,分析了华北地区东、西部分区清晰的震相特征。利用地壳分层构造特征以及理论走时计算等方法对人工震相读数结果进行了分析比较。另外还重点讨论了在华北地区区域测震台网常规震相分析工作中应该引起高度重视的深度震相sPn及其在震源深度准确测定中推广使用的可能性。     

The stability of fission tracks in epidote and vesuvianite

The stability of fission tracks in epidote and vesuvianite (idiocrase) was studied at different temperatures for several periods of time. The tracks in epidote are almost as heat-resistant as those in garnet; in vesuvianite they are much less stable. These results are in line with the rule that tracks in minerals with high lattice energies need higher activation energies to fade than in minerals with low lattice energies.     

Nuclide analyses of rare earth elements of the Oklo uranium ore samples: a new method to estimate the neutron fluence

Isotopic ratios and abundances of all REE in two Oklo ore samples have been measured. We have succeeded in developing a new method to estimate the neutron fluence, the conversion factor of uranium and the average neutron energy (or temperature) based on Gd and U isotopic ratios. This new calculation is found to be useful in evaluating those parameters for the natural nuclear reactors at Oklo. Comparison is made between the neutron fluence values evaluated by our new method employing Gd isotopes and a previous one [11] employing Sm and Nd isotopes. The relative agreement becomes better with the increase of fluence. A relationship between the abundances of fissiongenic nuclides of La, Ce, Nd, Sm, and Gd and their mass numbers is also presented.     

The use of natural tracers as indicators of soil-water movement in a temperate semi-arid region

In a semi-arid area of southern Australia a change in land use from Eucalyptus scrub to cropping with wheat is shown to have caused considerable change in the mechanism of the movement of soil water and the amount of deep drainage. Chloride concentrations of soil water have been used to show the mean annual amount of deep drainage increases from less than 0.1 to 3 mm yr.⁻¹ following clearing of the native vegetation.

The concentration of environmental tritium in soil water beneath the native vegetation is consistent with the hypothesis that some relatively recent water (post 1960) has penetrated to depths of at least 12m along channels occupied by living roots. Where the native vegetation has been cleared, no water which fell as rain since 1960 was found at depths greater than 2.5 m.

¹⁸O and deuterium concentrations suggest that some water movement to the roots of the native vegetation is in the vapour phase.     

Fission track tectonics: The tectonic interpretation of fission track apatite ages

Absolute uplift rates, regional uplift patterns, and time limits for uplift and fault movements can be studied with fission tracks in apatite. This is demonstrated for about 50 apatites from the Swiss and Italian Alps. Due to the relatively low thermal stability of tracks in apatite, the fission track ages of apatites from this area define the time when these rocks cooled down to temperatures to 125 ± 20°C.     

The nuclei of natural cloud formation part II: The supersaturation in natural clouds and the variation of cloud droplet concentration

Summary Calculations are performed to determine the time variation of supersaturation during cloud formation. It is shown that a simple expression can be used to obtain the maximum supersaturation (and hence the number of nuclei activated) as a function of updraught velocity and nucleus spectra insert omitted portion of copy reported in Part 1 and it isshown that they lead to cloud droplet concentrations which agree with those actually observed.     

Age and intensity of thermal events by fission track analysis: The Ries impact crater

A thermal event reduces the number of previously registered fission tracks in a mineral dependent upon the track retention properties of the individual mineral. Apatite, sphene and zircon have retention properties over a wide range of temperatures (from 100° to 550°C); apatite data reveal information at lowest temperatures while sphene and zircon data are useful for higher temperatures.Thermal events within this temperature range of 100°C to about 550°C are suitable for study with this technique. The age of the event is determined from samples in which the fission tracks are completely erased, while minerals containing partially removed (erased) tracks provide information on the temperatures occurring during the thermal event.As a test case, the analysis of the temperatures developed by the meteorite impact which produced the Ries crater at 14.7 m.y. ago is presented.     

Comparisons of wetland and drainage lake influences on stream dissolved carbon concentrations and yields in a north temperate lake-rich region

Processes occurring at various scales interact to influence the export of organic carbon from watersheds to freshwater ecosystems and eventually the ocean. The goal of this study was to determine if and how differences in wetland extent and presence of lakes influenced dissolved organic carbon (DOC) concentrations and yields in streams. We monitored stream flow, DOC and dissolved inorganic carbon concentrations periodically for 2 years at four sites with forested watersheds, four sites with wetland watersheds, and four sites with wetland watersheds that also contained in-network lakes. As expected, the presence of wetlands resulted in higher DOC concentrations and yields, but the impact of lakes was less clear on the magnitude of DOC concentrations and yields. With respect to temporal dynamics, we found positive relationships between stream flow and DOC concentration (median r² = 0.89) in streams without upstream lakes. The relationships for forested sites are among the strongest reported in the literature, and suggest a clear shift in hydrologic flowpath from intersecting mineral soils at low flow, to organic soils at high flow. In streams with upstream lakes, the relationship between flow and concentration was non-significant for three of four sites unless time lags with flow were applied to the concentration data, after which the relationship was similar to the non-lake streams (median r² = 0.95). These findings suggest that lakes buffering temporal patterns in streams by hydrologically delaying pulses of carbon, but provide little support that in-line lakes have a net effect on carbon exports in this region.     

The impact of natural vegetation restoration on surface soil moisture of secondary forests and shrubs in the karst region of southwest China

Soil moisture is crucial to vegetation restoration in karst areas, and climate factors and vegetation restoration are key factors affecting changes in soil moisture. However, there is still much controversy over the long-term changes in soil moisture during vegetation restoration. In order to reveal the changes in soil moisture during vegetation restoration, we conducted long-term positioning monitoring of soil moisture at 0–10 and 10–20 cm on secondary forests sample plot (SF, tree land) and shrubs sample plot (SH, shrub land) in karst areas from 2013 to 2020. The results showed that the aboveground biomass of SF and SH increased by 50% and 240%, respectively, and the soil moisture of the SF and SH showed an increasing trend. When shrubs are restored to trees in karst areas, the soil moisture becomes more stable. However, the correlation coefficients (R²) between the annual rainfall and the annual average soil moisture of SF and SH are 0.84 and 0.55, respectively, indicating that soil moistures in tree land are more affected by rainfall. The soil moisture of shrubs and trees are relatively low during the months of alternating rainy and dry seasons. Rainfall has a very significant impact on the soil moisture of tree land, while air temperature and wind speed have a significant impact on the soil moisture of tree land, but the soil moistures of shrub land are very significantly affected by rainfall and relative humidity. Therefore, during the process of vegetation restoration from shrubs to trees, the main meteorological factors that affect soil moisture changes will change. The results are important for understanding the hydrological processes in the ecological restoration process of different vegetation types in karst areas.     

The effect of forestry drainage operations on upland sediment yields: A case study

Forestry is generally considered to be a land use giving low sediment yields. However, in Britain most forestry is on land that requires extensive drainage, and it was found that the drainage of a small upland catchment resulted in sediment yields over the following five years equivalent to nearly half a century's load at pre-drainage rates. Subsequent sediment yields did not decline to pre-drainage levels, but remained about four times higher, as a result of erosion of the drains.     

The effect of forestry drainage operations on upland sediment yields: The results of a storm-based study

The effects of pre-afforestation open ditching on the sediment yield of an upland catchment in the Southern Pennines, England are described. Marked increases in the production of suspended sediment following ploughing caused major pollution of a local reservoir. Sediment supply prior to ditching was limited and easily exhausted, but afterwards remained plentiful, allowing sustained erosion during periods of storm runoff. Large volumes of sediment were carried into the reservoir during the winter of 1980–81. More recently, exhaustion of supplies of loose material in the ditches and revegetation have led to a lower rate of sediment output.     

Studies on vertical total-beta-activity profiles of fission products in the accumulation area of the Stubacher Sonnblickkees (Hohe Tauern,Salzburg, Austria)

Summary In the years of 1965 and 1966 continuous vertical sets of samples were bored from pits comprising the uppermost perannual snowcover in the accumulation area of the Stubacher Sonnblickkees (Hohe Tauern, Salzburg, Austria). The total-beta-activity of the samples was measured in order to study the changes of the vertical distribution of fission products by summerly melting processes. An enrichment of fission products was found in the layer under the late, summer horizon. However, the weak activity of the layer underneath accumulated during the winter period is hardly influenced by meltwater percolation from the superimposed layer with high activity.An 11.75 m deep firn pit covers, the annual layers of net accumulation from 1960/61 to 1965/66. The most remarkable activity variation of the entire total-beta-activity profile of this pit is a maximum at the coinciding late summer horizons of 1962 and 63. This activity maximum proves that mass budget years with heavy fission product debris and high melting conditions cause a strong enrichment and high retention of the remaining layer for fission products. It can be assumed that this characteristic feature of the vertical activity distribution will be also found on neighboring glaciers in the region of the Mittlere Hohe Tauern. Because its relatively long time stability it is especially interesting for future dating purposes.Moreover, it was found that the period from 1961/62 to 1963/64 shows a high fission product activity in contrast to the low radioactive period from 1964/65 to 1965/66. This behavior of the firn activity is in agreement with the one of the air and the precipitation during these years. The characteristic changes of the total-beta-activity of the firn at the late summer horizon of 1964 can be also used for dating purposes.

---

Zusammenfassung In den Jahren 1965 und 1966 wurden im Akkumulationsgebiet des Stubacher Sonnblickkees, (Hohe Tauern, Salzburg) aus Schneeschächten kontinuierliche Probenserien entnommen, welche die Akkumulation des laufenden hydrologischen Jahres erfassen. Die Proben wurden auf Gesamt-Beta-Aktivität untersucht, um die Veränderung der Vertikalverteilung der Spaltprodukte durch sommerliche Abschmelzvorgänge zu studieren. Als Ergebnis zeigt sich eine Spaltproduktanreicherung der Schicht unter dem Spätsommerhorizont, wobei jedoch die geringe Aktivität der darunterliegenden Winterschicht durch Einsickern von Schmelzwasser aus der darüberliegenden stark mit Spaltprodukten angereicherten Schicht kaum beeinflußt wird.Ein 11.75 m tiefer Firnschacht umfaßt die Jahresrücklagen von 1961/60 bis 1965/66. Als hervorstechendstes Merkmal der Vertikalverteilung der Gesamt-Beta-Aktivität ergibt sich ein Maximum an den zusammenfallenden Spätsommerhorizonten 1962 und 1963. Dieses Aktivitätsmaximum zeigt, daß in Haushaltsjahren mit starkem Fallout und starker Abschmelzung eine beachtliche Anreicherung sowie ein gutes Retentionsvermögen der verbleibenden Schicht für Spaltprodukte auftreten. Dieses charakteristische Aktivitätsmerkmal kann auch auf benachbarten Gletschern im Gebiet der Mittleren Hohen Tauern erwartet werden. Zufolge der guten Stabilität dieses Merkmals ist es für künftige Datierungszwecke besonders interessant.Weiters weist die Periode von 1961/62 bis 1963/64 hohe Spaltproduktaktivitäten im Gegensatz zur Periode 1964/65 bis 1965/66 auf. Dieses Ergebnis stimmt auch mit dem Verlauf der Luft-und Niederschlagsaktivität in den entsprechenden Jahren überein. Die charakteristische Abnahme der Gesamt-Beta-Aktivität des Firns über dem Spätsommerhorizont 1964 kann ebenfalls für Datierungszwecke verwendet werden.