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1.
Six typical red clay profiles were sampled from Tangxi (TX),Langyaz (LYZ),South Shangshanwen (SSW),Xianqiao (XQ),Qijian (QJ) and Huhaitang (HHT) of Jinhua-Quzhou Basin,Zhejiang Province of China to evaluate the characteristics of grain size composition,distribution and parameters of red clays and to reveal the origin of red clays and interpret possible implications for paleoclimate in subtropical China.The results showed that red clays in TX,LYZ and SSW were fine and uniform,with no>2mm gravels and little>63μm fraction.They had a high content of 10–50μm fraction,so-called"basic dust fraction",and showed unimodal distributions,which were very comparable to those of the Xiashu Loess in southeastern China and the loess in North China.All these features reflected marked aeolian characteristics of the red clays in these areas.Red clays in XQ and QJ were much coarser than those in TX,LYZ and SSW,with high contents of >63μm fraction and even containing>2 mm gravels in some layers.The grain size distribution patterns showed significantly progressive trends from the lower profile to the upmost layer and could not be compared with those of the loess in North China or the Xiashu Loess,implying they might be derived from underlying parent rocks and had some inherited properties from bedrock.Red clays in HHT had high contents of>63μm fraction and contain many >2mm gravels in each layer.The grain size frequency curves showed multiple-peaks and some abrupt variations were also observed on the profile,revealing its alluvial or diluvial origin in HHT.The multiple origins of red clays reflected the diversity and complexity of the Quaternary environment in South China.It can be concluded that grain size is an efective proxy indicator for the origin of most deposits. 相似文献
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A thin layer of yellow-brown-colored earth was generally found on Quaternary red clay in Jiujiang, Jiangxi Province. A typical profile was established. Both particle size distribution and REE (rare earth elements) characteristics of the yellow-brown-colored earth of the profile fully suggested its aeolian origin and close similarity to Nanjing Xiashu loess. The study also implied aeolian origin of the underlying Quaternary red clay. Compared with the red clay, the yellow-brown-colored earth was less weathered because of its lower content of free iron and higher mole ratios of SiO2/Al2O3 and SiO2/(Fe2O3+Al2O3) as well as its less developed chemical microtextures of quartz grains. In order to study the ages of the two deposits comparatively, the thermoluminescent dating method was used. As a result, the bottom of the yellow-brown-colored earth was dated to 60±5 ka B. P. and the upper part of the red clay 388±54 ka B. P. It was suggested that the yellow-brown-colored earth was formed in the Late Pleistocene and was probably the aeolian deposit of the Last Glacial, which corresponded with the Malan loess in the Loess Plateau of the northwestern part of China; while the underlying red clay was formed in the Middle Pleistocene. A "yellow cap" on Quaternary red clay in Jiujiang implied a great climatic and environmental variation in the beginning of the Late Pleistocene in the southern part of China, especially in the middle and lower reaches of the Yangtze River. The event not only halted the rubification, once dominating the region, but also produced a widespread covering of aeolian deposit, as only occurred in the cold and dry
environment. 相似文献
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The stability of aggregates in the surface soil is crucial to soil erosion and runoff generation. Thus, to understand the stability and the breakdown mechanisms of soil aggregates as well as the relationship between aggregate stability and selected soil chemical properties, such as different forms of Fe and A1 oxides, organic matter, CEC and clay content, the aggregates of slightly and severely eroded red soils derived from Quaternary red clay in subtropical China were analyzed using the routine wet sieving and the Le Bissonnais methods. The results indicated that the aggregates of the severely eroded soils were more stable than those of the slightly eroded soils. Different aggregate breakdown mechanisms resulted in different particle size distribution. The slaking from entrapped air in aggregates severely destroyed the soil aggregates,especially in the slightly eroded soils. Meanwhile, mechanical breakdown and microcracking had little effect on the aggregates compared to slaking. The fragments resulting from slaking were mainly microaggregates that increased in size with increasing clay content. The main fragment size of the slightly eroded soils was 1.0-0.2 mm, while for the severely eroded soils it was 5.0-2.0 mm and 1.0-0.5 mm. Overall, more than 20% of the fragments were smaller than 0.2 mm.In addition, aggregate stability was positively and often significantly correlated with Fed, Ald, Feo and clay content, but significantly and negatively correlated to SOC. 相似文献
4.
Trace element (TE) and rare earth element (REE) contents in red soils from the Dongting Lake area of China were determined to understanding the provenance and weathering characteristics of the red soils. The results showed similar REE distribution patterns among red soils from the Dongting Lake area, Xiashu loess from Zhenjiang, loess and the Pliocene red soil from the Loess Plateau. These patterns implied a similar provenance from dust-storms, except for red soil R5 which formed by bedrock weathering and had significant light REE (LREE) enrichment and heavy REE (HREE) depletion due to longer weathering periods and higher intensity of weathering. Trace element, especially the Rb/Sr and Li/Ba ratios, and REE, especially the LREE/HREE ratio and δEu could trace weathering intensity. Higher Rb/Sr, Li/Ba, and LREE/ HREE ratios and negative Eu anomalies were present in the red soil from the Dongting Lake area. The weathering intensity was in the decreasing order of R5 in the Dongting Lake area > red soil from the Dongting Lake area (including reticulate red soil, weak reticulate red soil, and homogeneous red soil formed by dust storms) > Xiashu loess from Zhenjiang > Loess-paleosol and Pliocene red soil from the Loess Plateau. Variations in the TE and REE contents of soil could be effectively used to study the provenance and the weathering intensity. 相似文献
5.
大田条件下水稻败育与铜缺乏的关系 总被引:1,自引:0,他引:1
The effect of liming 4 soils developed from Quaternary red clay and red sandstone on the cadmium forms and its toxicity were investigated.Liming the acid red soils could greatly reduce Cd toxicity to plants because the soluble Cd and organic Cd in the soils decreased significantly while Cd bound to minerals/oxides and residual Cd increased markedly with increasing lime rates(pH). 相似文献
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石灰处理对红壤中镉形态及其毒性的影响 总被引:1,自引:0,他引:1
The effect of liming 4 red soils developed from Quaternary red clay and red sandstone on the cadmium forms and its toxicity were investigated. Liming the acid red soils could greatly reduce Cd toxicity to plants because the soluble Cd and organic Cd in the soils decreased significantly while Cd bound to minerals/oxides and residual Cd increased markedly with increasing lime rates (pH). 相似文献
7.
中国亚热带红壤团聚体稳定性与土壤化学性质的关系 总被引:16,自引:1,他引:16
The stability of aggregates in the surface soil is crucial to soil erosion and runoff generation. Thus, to understand the stability and the breakdown mechanisms of soil aggregates as well as the relationship between aggregate stability and selected soil chemical properties, such as different forms of Fe and Al oxides, organic matter, CEC and clay content, the aggregates of slightly and severely eroded red soils derived from Quaternary red clay in subtropical China were analyzed using the routine wet sieving and the Le Bissonnais methods. The results indicated that the aggregates of the severely eroded soils were more stable than those of the slightly eroded soils. Different aggregate breakdown mechanisms resulted in different particle size distribution. The slaking from entrapped air in aggregates severely destroyed the soil aggregates, especially in the slightly eroded soils. Meanwhile, mechanical breakdown and microcracking had little effect on the aggregates compared to slaking. The fragments resulting from slaking were mainly microaggregates that increased in size with increasing clay content. The main fragment size of the slightly eroded soils was 1.0-0.2 mm, while for the severely eroded soils it was 5.0-2.0 mm and 1.0-0.5 mm. Overall, more than 20% of the fragments were smaller than 0.2 mm. In addition, aggregate stability was positively and often significantly correlated with Fed, Ald, Feo and clay content, but significantly and negatively correlated to SOC. 相似文献
8.
湿润速率和粘粒含量对红壤沟间侵蚀的影响 总被引:4,自引:0,他引:4
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. 相似文献
9.
红壤农业生态系统的养分循环、平衡及管理 总被引:5,自引:0,他引:5
An experiment was conducted in a red soil derived from Quaternary red clay in the Ecological Experiment Station of Red Soil, the Chinese Academy of Sciences, located in Yingtan (28° 15' 30' N, 116° 55' 30' E), Jiangxi Province. The results show that the major ways of nutrient loss are leaching and nitrogen volatilization. Rationalizing crop distribution, stimulating nutrient recycling, and improving internal nutrient flow are effective measures to decrease nutrient loss and to promote nutrient utilization efficiency. The important ways of regulating nutrient cycling and balance in the agroecosystem of the red soil are to establish optimal eco-agricultural models, practice balanced fertilization and combine the cropping system with the livestock system. 相似文献
10.
华南兴国县影响土壤侵蚀时空动力学的环境因素 总被引:7,自引:0,他引:7
WANG Ku SHI Xue-Zheng YU Dong-Sheng SHI De-Ming CHEN Jing-Ming XU Bin-Bin LIANG Yin LI De-Cheng 《土壤圈》2005,15(5):620-627
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. 相似文献
11.
长江中游地区第四纪红土的二元结构及古环境意义 总被引:3,自引:0,他引:3
在长江中游地区的湖南和湖北两省,选择宜昌、咸宁、常德、长沙、株洲5个第四纪红土剖面,分析第四纪红土的粒度组成特征,研究红土的成因及南方古环境的演变。结果表明,这些地区第四纪红土的粒度组成呈明显的二元结构:剖面上部(宜昌剖面0~320 cm,咸宁剖面0~220 cm,常德剖面0~270 cm,长沙剖面0~280 cm,株洲剖面0~150 cm)粒度细小而均匀,砂粒含量低,大部分小于1%;粗粉砂(又称风尘"基本粒组")相对富集,平均含量分别为34.38%、32.29%、32.48%、31.69%和31.86%。而且土壤样品粒度频率分布曲线与安徽宣城第四纪红土很相似,与镇江下蜀黄土也有明显继承性。这些特性均反映了剖面上层红土的风成特性。但研究剖面下部红土,粒度组成有明显不同:含有砾石,砂粒含量较高,不同粒度组分垂向变化明显,粒度频率分布曲线与宣城红土和下蜀黄土有显著差异,表现出明显的冲、洪积相特性。第四纪红土的"二元结构",反映了研究区域第四纪古环境的多变性和复杂性:早期红土形成后,因受间冰期湿热气候的影响,多受流水作用改造;而晚期红土更多地受风尘堆积的影响,沉积后虽经过了强烈的原位风化,但仍保留了风尘沉积的特性。 相似文献
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母质对新形成腐殖质的影响 总被引:2,自引:0,他引:2
本文研究了在旱地和水田条件下,母质对新形成腐殖质的影响.供试物料为紫云英、绿萍、稻草和水葫芦.结果表明:1.除绿萍外,各物料腐解三年后均已分解较完全.腐解产物的C/有机N值和腐殖质组成均随原始物料而异.2.当植物物料和母质相同时,与水田条件下的相比,旱地条件下的腐解产物的C/有机N值大多较窄,中性糖量较高,六碳糖/五碳糖值较宽,腐殖酸的提取率较高.3.当水分条件和植物物料相同时,与第四纪红色粘土中的相比,下蜀黄土中腐解产物的胡敏酸的C/N值大多较窄,六碳糖/五碳糖值和胡敏酸/富里酸值大多较宽.作者认为,二者中腐殖质组成的差别在一定程度上系由于粘土矿物的组成不同所致. 相似文献
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Xue‐Feng Hu Wei Jiang Wei Ye Ming‐Neng Shen Wei‐Guo Zhang Hong‐Bo Wang Cheng‐Wen Lu Li‐Dong Zhu 《植物养料与土壤学杂志》2008,171(4):542-551
In order to investigate the paleoclimatic changes in S China during the late Quaternary and their influence on pedogenesis and soil classification, a yellow‐brown earth (YBE)–red clay (RC) profile in Langxi County, Anhui Province was studied. The grain‐size distribution and the major‐ and trace‐element compositions of the profile indicate that the YBE of the profile shares the same origin with the YBE in Jiujiang and Xuancheng and the Xiashu loess in Zhenjiang, and the underlying RC also has aeolian characteristics and shares the same origin with the Xiashu loess. Grain‐size characteristics, molecular ratios of SiO2/Al2O3, SiO2/(Al2O3+Fe2O3), and BA ([CaO+MgO+K2O+Na2O]/Al2O3) and other weathering indices (CaO/TiO2, MgO/TiO2, K2O/TiO2, Na2O/TiO2, and Rb/Sr) of the profile indicate that the RC is more strongly weathered than the YBE. Magnetic susceptibility (χlf) of the uniform red clay (URC) of the profile is significantly enhanced. However, that of the underlying reticulate red clay (RRC) is significantly decreased because of the paleogroundwater movement and cannot indicate its strong weathering properties. The YBE‐RC profile in Langxi County recorded a great climatic change during late Quaternary: At that time, the pedogenic development of the RC was terminated and widespread dust deposition occurred. The parent material of the RC may be aeolian deposits which were accumulated before the last interglacial and were strongly weathered and rubified under the subsequent interglacial climate. It is observed that red soils, derived from the RC, and yellow‐brown soils, derived from the YBE, coexist in the study area, which is contradictive to the theory of the zonal distribution of soils. Therefore, it is necessary to take into account the history of Quaternary climatic changes when studying pedogenesis. 相似文献
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皖南网纹红土的剖面风化特征及其古气候意义 总被引:4,自引:0,他引:4
气候变化下土壤物质过程的响应特征是全球变化研究的重要主题。选取安徽宣城剖面,通过元素分析,对其风化强度特征进行了研究。结合与黄土高原第四纪黄土、古土壤、江苏镇江下蜀土以及江西九江红土等典型风成堆积剖面的对比分析,得出以下结论:(1)宣城红土剖面经历了高强度的化学风化作用,长石损失殆尽,进一步的风化作用已导致其含K矿物(黑云母、伊利石和钾长石)的分解,次生粘土矿物以高岭石为主。此外,宣城红土与其他剖面相比,显著强于镇江下蜀土,远强于洛川黄土与古土壤,而与九江红土的风化程度较为相近。(2)在地形、母岩等条件相似的情况下,气候(特别是温度和降水量)是控制化学风化程度的主要因素,并且与温度相比降水因素可能起着更为重要的制约作用。(3)在地质历史时期,宣城→镇江→洛川,随着地域的北移,气候环境向干冷方向发展。(4)BA,Na/K和硅铁铝率的剖面变化特征揭示,中更新世早、中期,气候相对温暖潮湿,之后气候总体恶化,向干冷方向发展。但在此过程中,伴随着大姑-庐山间冰期和末次间冰期的到来气候又出现过两次短暂的回暖过程,并且在晚更新世早期呈现兼有干湿交替的特征。 相似文献