中国西南薄层砾石土喀斯特坡地土壤的137Cs分布特点

The fallout radionuclide cesium-137(137 Cs) has been widely employed as a tracer for assessment of soil loss from thick uniform soils;however,few studies have been conducted on thin stony soils on slopes underlain by carbonate rocks which are widely distributed in karst areas.Information derived from 137 Cs measurement of soil samples collected along a carbonate rock slope with thin stony soil where neither soil erosion nor deposition occurred was used to investigate the characteristics of 137 Cs redistribution in a karst area of Southwest China.The results indicated that the 137 Cs inventories of the surface soil on the slope studied were much lower than that of the local 137 Cs reference inventory and the 137 Cs activities were much higher than those on slopes with thick uniform soils.The spatial distribution of 137 Cs inventories was characterized by considerable variation.The high 137 Cs depletion in the stony soil of the slope studied was mainly because a considerable proportion of the fallout input of 137 Cs could be lost with runoff and the dissolution of carbonate particles in the soil promoted the loss of 137 Cs.These demonstrated that the rates of soil loss could not be estimated from the degree of depletion of the 137 Cs inventory relative to the local reference inventory for the thin stony soil of the rocky slope underlain by carbonate rocks in the study area in the way that has been widely used in areas with thick uniform soils.     

中国福建省土壤的主要粘土矿物

The clay minerals of more than 200 soil samples collected from various sites of Fujian Province were studied by the X-ray diffraction method and transmission electron microscopy to study their distribution and evolution.Montmorillonite was found in coastal solonchak,paddy soils derived from marine deposit,lacustrine deposit and river deposit,and some lateritic red soil,red soil and yellow soil with a low weathering degree.Chlorite existed mainly in coastal solonchak and paddy soil developed from marine deposit.1.4nm intergradient mineral appeared frequently in yellow soil,red soil and lateritic red soil.The content of 1.4nm intergradient mineral increased with the decrease of weathering degree from lateritic red soil to red soil to yellow soil.Hydrous micas were more in coastal solonchak,paddy soils derived from marine deposit,lacustrine deposit and river deposit.and puple soil from purple shale than in other soils.Kaolinte was the most important clay mineral in the soils iun this province.The higher the soil weathering degree,the more the kaolinite existed.From yellow soil to red soil to lateritic red soil,kaolinite increased gradually,Kaolinite was the predominant clay mineral accompanied by few other minerals in typical lateritic red soil. Tubular halloysite was a widespread clay mineral in soils of Fujian Province with varying quantities.The soil derived from the paent rocks rich in feldspar contained more tubular halloysite.Spheroidal halloysite was found in a red soil and a paddy soil developed from olivine basalt gibbsite in the soils in this district was largely“primary gibbsite” which formed in the early weathering stage.Gibbsite decreased with the increase of weathering degree from yellow soil to red soil to lateritic red soil.Goethite also decreased in the same sequence while hematite increased.     

上海地区水稻土氮素矿化模拟

Three types of paddy soils, derived from granite, Quaternary red clay and basalt, respectively, were selected to study the effects of Fe and Mn in paddy soils on methane production and emission through pot and incubation experiments. The results indicated that the difference of Fe and Mn in paddy soils was one of the important factors causing obvious differences in methane emission from different soil types. Soil Fe and Mn affecting methane emission from the paddy soils was likely through affecting soil Eh and forming Fe and Mn plaques on rice roots. Different rates and valences of added Fe and Mn significantly affected methane production from paddy soils. Therefore, this study enhanced understanding of processes controlling methane emission from paddy soils and may help to improve modeling and estimating regional and global methane emission from paddy soils.     

利用137Cs示踪技术评价东北黑土侵蚀和沉积过程

Soil and water losses through erosion have been serious in the black soil region of Northeast China. Therefore, a sloping cultivated land in Songnen Plain was selected as a case study to： 1） determine the ^137Cs reference inventory in the study area; 2） calculate erosion and deposition rates of black soil on different slope locations; 3） conduct a sensitivity analysis of some model parameters; and 4） compare overall outputs using four different models. Three transects were set in the field with five slope locations for each transect, including summit, shoulder-slope, back-slope, foot-slope, and toe-slope. Field measurements and model simulation were used to estimate a bomb-derived ^137Cs reference inventory in the study area. Soil erosion and deposition rates were estimated using four ^137Cs models and percentage of ^137Cs loss/gain. The ^137Cs reference value in the study area was 2 232.8 Bq m^-2 with ^137Cs showing a clear topographic pattern, decreasing from the summit to shoulder-slope, then increasing again at the foot-slope and reaching a maximum at the toe-slope, Predicted soil redistribution rates for different slope locations varied. Among models, the Yang Model （YANG-M） overestimated erosion loss but underestimated deposition. However, the standard mass balance model （MBM1） gave predictions similar to a mass balance model incorporating soil movement by tillage （MBM2）. Sensitivity analysis of the proportion factor and distribution pattern of ^137Cs in the surface layer demonstrated the impact of ^137Cs enrichment on calculation of the soil erosion rate. Factors influencing the redistribution of fallout ^137Cs in landscape should be fully considered as calculating soil redistribution rate using ^137Cs technique.     

作为颗粒运移的示踪剂的土壤7Be, 137Cs, 226Ra和228Ra的地球化学种类

A brunisolic soil collected from an erosive forest land(HF-1-1) and a yellow soil from and accumulative shallow basin(HF-6-1) in the watershed of Lake Hongfeng (HF) were used for activity measurements of ^7Be,^137Cs,^226Ra and ^228Ra in different geochemical speciation.More than 85% of ^7Be,^137Cs,^226Ra and 228Ra in the soils were bound to organic Fe-Mn oxy-hydroxide and residual fractions.They could move with soil particlesw and be used as tracers for the erosion and /or accumulation of soil particles.^7Be gohemical specition in the soils agreed with its trace for seasonal particle transport.^137Cs geohemial speciaiton was suitable for tracing soil particle accumulation and for sediment aating.^226Ra and ^228Ra were ombined in crystalline skeleton of clay minerals and mainly remained as residues in the soils and little was bound to the soluble,exchangeable and carbonate fractions.The differentiation of ^226 Ra/^228Ra activity ratios in different geoheical fractions in the soils could be used as a parameter to trace accumulation and /or erosion of soil particles.     

湿润速率和粘粒含量对红壤沟间侵蚀的影响

An aggregate stability test and a simulated rainfall test were conducted on four representative Ultisols from southeastern China. The soils selected, with clay contents ranging between 117 and 580 g kg-1 , were derived from shale and Quaternary red clay. The stability of aggregates (2–5 mm in diameter) obtained from the soil samples were determined by the Le Bissonnais method. For determination of infiltration, runoff, and erosion, the soil samples were packed in 30 cm × 60 cm trays, wetted at rates of 2, 10, and 60 mm h-1 , and then exposed to simulated rainfall at 60 mm h-1 for 1 h. The results indicated that both aggregate stability and slaking caused by fast wetting increased with increasing clay content. The effect of wetting rate (WR) on infiltration and seal formation varied with clay contents. In the soil with low clay content (sandy loam), the infiltration rate was affected slightly by WR due to low aggregate stability and slaking. In the soils with medium clay content (silt clay loam and clay), WR affected infiltration significantly due to the high aggregate slaking force. In the soil with high clay content, the effect of WR on infiltration was significant, but not as evident as in the soils with medium clay content, which may be related to high aggregate stability by wetting partially compensating for slaking force. The effect of WR on soil loss was similar to that of runoff, but more pronounced. The findings from this study indicated that the relationship between wetting rate and clay content should be considered when predicting interrill erosion in Ultisols.     

土壤溶质迁移的柱滞留方程

The relationship between magnetic properties and particle size of soils derived from metamorphic rock,basalt,granite,Quaternary red clay,limestone and mudstone from Zhejiang Province,East China was studied,Based on the variations of the mass magnetic susceptibility (χ),anhysteretic remanent magnetization (ARM),and saturation isothermal remanent magnetization (SIRM) with soil particle size,the relationship could be classfied into three groups.For the soils derived from metamorphic rock and basalt,magnetic values were the highest in the gravel and coarse sand fractions and decreased with decreasing soil particle size.The soils derived from sedimentary rock had a bimodal distribution of magnetic values.with peaks in 1-0.5 and 0.005-0.0005mm fractions.The soil developed on granite was characterized by a peak of magnetic value in 0.001-0.0005mm fractions.The soil developed on granite was characterized by a peak of magnetic value in 0.001-0.0005 mm fractions.Frequency-dependent susceptibility(χfd)and ratios of magnetic parameters (ARM/χ,SIRM/χand SIRM/ARM) of soil particle fractions showed that variations in ferrimagnetic grain size paralleled those in particle size,χfd peaked in caly fraction and decreased with increasing particle size,irrespective of soil parent materials.The acquisition curves of IRM and demagnetization paramenter of different soil particles indicated that there were different magnetic minerals assemblages in different particle fractions.     

石灰氮对土壤中尿素转化的影响

Laboratory incubation experiment was conducted to study the effect of lime nitrogen(LN) on transfor-mation of urea-N in three paddy soils.The results showed that LN had an inhibitory effect on urease activity in these soils especially in the first 5 days.and that in the first 20 days of incubation,the amount of NH4^ -N derived from urea was lower in the soil with LN than in the soil without LN,While after 30 days the amount of NH4^ -N was higher in the mature haplic paddy soil developed on Quaternary red clay (MHPS)with LN than that in the soil without LN.The amount of NH3-N volatilized was decreased in the earlier stage and increased in the later stage of incubation in the MHPS by the addition of LN.     

土地利用史对水田甲烷的排放和甲烷植物的影响

The characteristics of methane emission were compared among six types of upland and paddy soils developed from different materials with distinct physical and chemical properties after planting rice.The fluxes of methane emission in submerged soils from the upland were obviously lower than those from the paddy rice field.The flux of methane emission in the paddy soil developed from fluvo-aquic soil was the largest among all the types of soils.Planting of rice was heplful to emission of methane in soils.The amounts of various groups of methanogenic flora were conformed with the differences among the fluxes of methane emission in various types of soils.Methane formation was observed in each type of air-dried soils stored for a long time after addition of water and incubation at 35℃.     

华南兴国县影响土壤侵蚀时空动力学的环境因素

By using soil erosion maps of four different time periods and a digital elevation model (DEM), in combination with the remote sensing and GIS technologies, soil erosion dynamics in Xingguo County of Jiangxi Province in South China were analyzed on both temporal and spatial scales in soils of different parent materials, altitudes and slopes. The results showed that from 1958 to 2000 severe soil erosion was coming under control with a decreasing percentage of the land under severe erosion. It was also found that the soils developed from Quaternary red clay, granite and purple shale were more susceptible to soil erosion and that areas sitting between 200 to 500 m in altitude with a slope less than 3° or between 7° to 20° where human activities were frequent remained to be zones where soil erosion was most likely to occur. These areas deserve special attention in monitoring and controlling.     

Einfluß des Jahresniederschlags und der Bodenart auf die 137Cs-Tiefenverteilung in Böden Südchiles

The influence of mean annual rainfall and soil texture on the ¹³⁷Cs vertical distribution in soils from southern Chile The influence of mean annual rainfall and soil texture on the vertical distribution of ¹³⁷Cs from global fallout was studied in undisturbed volcanic ash soils from southern Chile. The areal concentration and translocation depth increase with the mean annual precipitation. In spite of the high rainfall at the sampled area (970 - 2500 mm a^?1), the highest ¹³⁷Cs contamination was found in the upper 10 cm layer. The vertical migration is reduced by the high adsorption capacity of these volcanic ash soils, but on the other side increased in soils with high large-pore volumen. The translocation depth reaches only up to 26 cm in the clay soils, 35 cm in the silty soils and 70 cm in the sandy soil.     

Relating Intensity of Soil Redistribution to Land Use Changes in Abandoned Pyrenean Fields Using Fallout Caesium‐137

Fallout caesium‐137 has been used to trace soil redistribution in abandoned fields located in the Central Spanish Pyrenees. A total of 28 fields with different lengths, slope angles and time since abandonment were selected on a representative south‐facing slope of the Estarrún valley. The local reference inventory and the magnitude and spatial distribution of ¹³⁷Cs inventories within these fields were documented and used as a basis for assessing patterns of soil redistribution. The local reference inventory was estimated to be 4,500 Bqm⁻². Within the fields, the average ¹³⁷Cs inventory at the top of the slope was 3,920 Bqm⁻², and accumulation of soil at the bottom of the slopes was demonstrated by an average ¹³⁷Cs inventory of 5,320 Bqm⁻². Deviations from the reference inventory were highest for fields with the longest slopes that had been abandoned for less than 30 years. Here, increases in the ¹³⁷Cs inventory, relative to the reference inventory, in excess of 20% were found at the bottom of the slopes. Considering all the fields and all geomorphic positions within the fields, the greatest ¹³⁷Cs losses and gains were found in the fields with the longest duration of abandonment, indicating more intense soil redistribution. Irrespective of the timing of abandonment, the ranges of ¹³⁷Cs inventories in the fields were found to be proportional to the water erosion index. The ¹³⁷Cs technique demonstrated that patterns of sediment redistribution were closely related to the topographic and physiographic characteristics of the slopes. Copyright © 2017 John Wiley & Sons, Ltd.     

Radio-caesium fixation dynamics: measurement in six Cumbrian soils

Five peat soils and a mineral soil were artificially contaminated with ¹³⁷Cs. Soil solution activity and radio–lability of ¹³⁷Cs were monitored over 709 days to quantify progressive ¹³⁷Cs fixation. The peat soils fixed large amounts of ¹³⁷Cs, but less than the mineral soil did. Distribution coefficients (K_d, cm³ g^?1) ranged from 30 to 5000 at the end of equilibration. A labile ¹³⁷Cs distribution coefficient, K_dt, was estimated by a method involving solid ? solution equilibration in dilute solution. In a separate study several concentrations of KCl were added to soils in increasing concentration both before and after the addition of ¹³⁷Cs. Differences in apparent adsorption strength of radiocaesium indicated that K⁺ induced the collapse of expanded mineral interlayers, thereby trapping ions. It seemed that ^I37Cs adsorbs at sites in the small micaceous clay fraction of the peat soils. The different rates of ¹³⁷Cs adsorption and fixation in the peat and mineral soils, in which the rate of access of ¹³⁷Cs to fixation sites in peat soils is less, seems to have been caused partly by lack of K, and partly by the scarcity of fixation sites.     

Exchangeable Cs/K ratio in soil is an index to estimate accumulation of radioactive and stable Cs in rice plant

Pot and field experiments were conducted to clarify the effect of soil exchangeable potassium (K) and cesium-137 (¹³⁷Cs) on ¹³⁷Cs accumulation and to establish soil index in rice (Oryza sativa L.). Four paddy soils in Fukushima Prefecture, Japan, showing different transfer factors for radioactive Cs derived from the accident of Fukushima Daiichi Nuclear Power Station in the field were compared in terms of ¹³⁷Cs accumulation in rice in a pot experiment. ¹³⁷Cs accumulation in shoots and brown rice widely varied among soils with the transfer factor ranging from 0.018 to 0.068 for shoots and 0.004 to 0.065 for brown rice. ¹³⁷Cs concentration in brown rice and shoots tended to decrease with higher levels of soil exchangeable K, and they were more closely related to the exchangeable Cs/K ratio. Similar relationships between the Cs/K ratio and Cs accumulation in plants were obtained for the stable isotope cesium-133 (¹³³Cs). The distributions of ¹³⁷Cs and ¹³³Cs in grains were also similar and variable among soils. The transfer factors obtained in pot experiments mostly agreed with field observations. The results imply that the exchangeable ¹³⁷Cs/K can be a potential soil index to estimate ¹³⁷Cs accumulation in rice.     

Soil erosion and deposition rates in a cultivated catchment area in central Greece, estimated using the Cs technique

The spatial variation of soil erosion and deposition rates was studied in a small catchment cultivated by rainfed agriculture, in the Mouriki area, Viotia Greece, using the ¹³⁷Cs technique. A 25 m grid was established parallel to the slope and the ¹³⁷Cs inventories were defined for the grid points. After establishing the local reference inventory, the soil erosion and deposition rates were estimated using the ¹³⁷Cs residuals for individual points on the grid in conjunction with the four conversion (calibration) models described by Walling and He (2001) [Models for converting ¹³⁷Cs measurements to estimates of soils redistribution rates on cultivated and uncultivated soils]. The conversion models were validated by means of sensitivity analysis and using local experimental data. The resulting estimates of soil redistribution rates were interpolated by means of kriging, using Surfer Golden software. The magnitude of the soil erosion rates depend on many factors, including the location of the sampling point, the local slope, and the soil properties. The mass balance model 2 (MBM2) and mass balance model incorporating soil movement by tillage (MBM3) conversion models predict soil redistribution rates of the same order of magnitude as the experimental data and are able to take account of Chernobyl fallout. Predicted soil erosion rates for catchment grid varied from 6.71 to 85.55 t ha⁻¹ per year using MBM2 and from 3.54 to 95.78 t ha⁻¹ per year using MBM3. Deposition rates varied from 1.23 to 168.19 t ha⁻¹ per year using MBM2 and from 3.24 to 189.18 t ha⁻¹ per year using MBM3. High correlation was apparent between erosion/deposition rates (MBM2) and soil P (P<0.001), soil K (P<0.001), soil organic matter % (P<0.05), point slope (P<0.05), clay % (P=0.053) and altitude (P=0.057). The total soil losses from the catchment have been estimated at 18.34 t ha⁻¹ per year using MBM2 and 22.12 t ha⁻¹ per year using MBM3.     

我国南方水稻土供硅能力的研究

硅肥对水稻的增产作用,在日本早就有了肯定的结果^[1]。近年来试验证明,在我国南方部分土壤上,水稻施用硅肥有增产效果^[2]。为了明确水稻施用硅肥肥效和土壤类型之间的关系,提出我国南方水稻施用硅肥有效的土壤和植株指标,本文对我国长江以南主要类型水稻土供硅水平的研究进行了总结。     

The 137Cs technique applied to steep Mediterranean slopes (Part I): the effects of lithology,slope morphology and land use

Concentrations in the soil of anthropogenic and natural radionuclides have been investigated in order to assess the applicability of the ¹³⁷Cs technique in an area of typical Mediterranean steep slopes. This technique can be used to estimate net soil redistribution rates but its potential in areas with shallow and stony soils on hard rock lithology have not been evaluated so far. In this research, the validity of using this technique in stony shallow soils at very steep slopes is discussed together with the relations between radionuclide concentrations and other soil properties, lithology, slope morphology and land use in a Mediterranean environment. Both natural Potassium-40 (⁴⁰K), Uranium-238 (²³⁸U), Thorium-232 (²³²Th) and anthropogenic Caesium-137 (¹³⁷Cs) radionuclides have been determined in samples taken along slope transects on uncultivated serpentinite soils and cultivated gneiss soils. In addition to the radionuclide concentrations, parameters such as slope position, slope angle, aspect, soil depth, surface stone cover, moss, litter, vegetation cover, soil crust, stone content and bulk density have been quantified.All the natural radionuclides ⁴⁰K, ²³⁸U, ²³²Th show significantly higher concentrations in the gneiss than in the serpentinite soils, opposed to the ¹³⁷Cs concentration, which is found significantly higher in the serpentinite soils probably because of the difference in clay mineralogy. The exponential decreasing depth distribution of ¹³⁷Cs and its homogeneous spatial distribution emphasise the applicability of the ¹³⁷Cs technique in this ecosystem.Lithology determines the concentration of natural and anthropogenic radionuclides. Land use determines the relations between ¹³⁷Cs concentration/inventory and some soil characteristics. Higher ¹³⁷Cs concentration and inventory are associated with higher percentages of vegetation cover, higher percentage of stones in the soil and higher values of soil bulk density in cultivated gneiss soils. Slope morphology and land use influence the soil redistribution at slope scale. The gneiss slopes show a zonation of four to five areas of differential erosion/accumulation processes corresponding with more regular slopes and soil redistribution due to water erosion and to tillage translocation and erosion. The serpentinites, as an example of a more unstable slope type, show more erosion areas with less accumulation downslope and soil redistribution due to water erosion.     

Assessment of soil losses on cultivated land by using the Cs technique in the Upper Yangtze River Basin of China

This paper presents the results of using the ¹³⁷Cs technique to assess soil erosion rates of both sloping cultivated land and flat terraces in the Upper Yangtze River Basin, China. The study was carried out on eighteen sloping cultivated fields and four flat terrace fields in eight counties and cities over the eastern part of the basin. The ¹³⁷Cs-reference inventory ranged from 620.5 to 2573.2 Bq/m². For the 18 sloping cultivated fields, the average ¹³⁷Cs inventory over a field ranged from 204.9 to 1847.7 Bq/m², which accounts for 15–77% of the local ¹³⁷Cs reference inventory, and the average water erosion rate ranged from 758 to 9854 t/km² per year, with erosion rates of <1000 t/km² per year in two fields; 1000–5000 t/km² per year in eight fields; and >5000 t/km² per year in eight fields. It is apparent that most of the sloping cultivated fields suffer severe or very severe soil erosion. For the four terrace fields under this study, the average ¹³⁷Cs inventory over a field ranged between 915.8 and 2675.4 Bq/m², which accounts for 97–104% of the local ¹³⁷Cs reference inventory. However, water erosion is very slight on the terrace fields and little soil is lost from the terraces. The study also indicated that the severity of soil erosion is strongly related to soil texture and slope gradient.     

赣南红壤丘陵区137Cs示踪土壤侵蚀对土壤养分元素的影响

赣南红壤丘陵区是我国土壤侵蚀与土地退化比较严重的地区,以南丰县为例,应用137 Cs示踪技术探讨不同土地利用方式下土壤侵蚀与养分元素的关系。结果表明:(1)湿地松林、桔园、水田3种土地利用方式作用下土壤中137 Cs与养分元素分布差异显著,在垂直剖面上,湿地松林137 Cs含量呈指数递减分布,水田与桔园137 Cs含量因人为干扰在耕层内均匀分布;有机质与137 Cs有相似的分布特征;全氮、碱解氮、速效磷、速效钾含量均呈现一定表聚性。(2)位于坡地的2种土地利用方式中,湿地松林137 Cs、全氮、碱解氮、速效磷、速效钾、有机质含量均表现为下坡>上坡>中坡;桔园137 Cs活度表现为中坡>下坡>上坡,全氮、碱解氮、速效磷表现为下坡>中坡>上坡,而速效钾、有机质最大值均出现在上坡。(3)相关性分析表明,土壤137 Cs与有机质、全氮、碱解氮显著正相关,表明小流域有机质、氮元素可能与137 Cs有相同的物理运移方式,pH与137 Cs显著负相关,速效磷、速效钾则与137 Cs不相关。(4)3种土地利用方式中位于小流域谷地的水田137 Cs、有机质、全氮、碱解氮含量最高,坡地上桔园坡面137 Cs与土壤养分元素含量均高于湿地松林地,表明一定程度的坡改梯桔园种植模式能有效缓解土壤侵蚀与养分流失,改善区域生态环境。