A world model of soil carbon dioxide: A reply     

George A. Brook  Elgene O. Box 《地球表面变化过程与地形》1984,9(1):85-87

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Rate of soil erosion processes on vineyards in central Piedmont (NW Italy)     

Domenico Tropeano 《地球表面变化过程与地形》1984,9(3):253-266

The ‘Tertiary Basin of Piedmont’ is a hilly region, mainly composed of marine sediments, such as marls, silts and sands. The slopes, largely devoted to grape production, are usually kept bare of vegetation and are thus prone to soil erosion processes. For two years we have measured soil loss in relation to rainfall on experimental plots located in vineyards. In all the plots considered erosion started with low rainfall intensities (0·07 mm/min), and above 0·4 mm/min the amount of soil loss dramatically increased (to over 1800 g/m in one event). Most of the erosion occurs during summer rainstorms, but the behaviour of the soil under erosive rainfalls is very different from one site to another, depending only in part upon the various rainfall rates, soil and geometrical characteristics of the plots. It can be seen that soil loss varies from nearly negligible values (20 g/m/yr) to unacceptably high levels (to over 4·7 kg/m/yr), according to the different types of land cultivation. Deep ploughing and heavy herbicide treatment give rise to accelerated erosion processes leading to soil losses much higher than in other vineyard plots in Europe.  相似文献   

The effects of soil piping on contributing areas and erosion patterns     

J. A. A. Jones 《地球表面变化过程与地形》1987,12(3):229-248

Natural piping doubles the dynamic contributing area on the upper Maesnant stream in mid-Wales, mainly through linking points well beyond the riparian zones of seepage to the stream. Both discharge and sediment transport rates in the major pipes are closely related to the size of shallow surface microtopographic hollows in which they lie, and which themselves are largely created by piping erosion. However, pipe dischrges are frequently generated by contributing areas larger than these surface depressions and some pipes run counter to the surface topography. The redistribution and acceleration of hillslope drainage processes by piping has implications for theories of hillslope development, especially through plan-form modifications, and also for channel discharge and erosion.  相似文献   

Suction-controlled triaxial testing: Laboratory procedures in relation to resistance envelope methods     

M. G. Anderson  M. J. Kemp 《地球表面变化过程与地形》1987,12(6):649-654

In certain tropical slopes it appears possible that soil suction may play a significant role in maintaining stability. This communication outlines a laboratory suction-controlled triaxial test that can be undertaken to validate the threshold suction predicted by resistance envelope methods. It is shown that for two sites examined in St. Lucia, West Indies, the results from such a test confirm results obtained by use of resistance envelopes.  相似文献   

TRPO萃取-固体荧光法测定土壤和空气尘埃中的铀     

王功鹏  赵法  周小民 《铀矿地质》1987,(2)

本文在研究了影响萃取的各种因素后,给出了用TRPO-OK萃取-固体荧光法测定土壤和空气尘埃中铀的方法。土壤和空气尘埃样品全程回收率分别为(89.6±11.8)％和(85.5±5.6)％,方法灵敏对土壤和空气尘埃样品分别为0.03μg·g~(-1)和0.02Pg·1~(-1)。样品中的常量离子对分析不产生明显干扰。操作简便、快速,适用于常规监测和本底调查。  相似文献   

Long-term erosion on granitic roadcuts based on exposed tree roots     

Walter F. Megahan  Kathleen A. Seyedbagheri  Patrick C. Dodson 《地球表面变化过程与地形》1983,8(1):19-28

Exposed roots were used to estimate soil and bedrock erosion on the cut slopes of a 45-year-old road constructed in granitic soils of the Idaho Batholith. The original roadcut surface was defined by projecting a straight line from the toe of the cut past the end of the exposed root to the intersection of a straight line projected along the surface of the hillslope. A cross-sectioning technique was then used to determine erosion to the present roadcut surface. A total of 41 exposed root sites were used to estimate erosion on a 1350 m-long section of road. Average erosion was 1·0 and 1·1 cm/year for soil and bedrock respectively. Buttressing by tree roots caused lower erosion rates for soil as compared to bedrock. Both soil and bedrock erosion rates showed statistically significant correlations with the gradients of the original cut slope. The bedrock erosion data provide a reasonable estimate of the disintegration rate of exposed granitic bedrock exhibiting the weathering and fracturing properties common to this area. The road is located in a study watershed where long-term sediment yield data are available. Sediment data from adjacent study watersheds with no roads were compared to sediment data from the roaded watershed to estimate the long-term increase in sediment yield caused by the road. The increase amounts to about 2·4 m³/year. This figure, compared to the average annual on-site road erosion, provides an erosion to sediment delivery ratio of less than 10 per cent. Based on study results, road construction and maintenance practices are suggested for helping reduce roadcut erosion.  相似文献   

A world model of soil carbon dioxide     

George A. Brook  Michael E. Folkoff  Elgene O. Box 《地球表面变化过程与地形》1983,8(1):79-88

Mean growing season soil PCO₂ data were obtained for 19 regions of the world in nine countries. Bivariate and multiple linear regression analysis with soil log(PCO₂) as the dependent variable and TEMP, PRECIP, log(AET), and log(PET) as the four climatic independent variables demonstrated that AET was the best independent predictor of soil PCO₂. An improved soil PCO₂-AET model was developed by assuming (1) that as AET approaches zero, soil PCO₂ approaches the atmospheric value and (2) that there is an upper limit to soil PCO₂ at very high AET. This model has the form log(PCO₂) = ?3·47 + 2·09 (1 ?e^{?0·0172 AET}) where AET is in mm. It explains 67 per cent of the initial variation in the soil PCO₂ data, predicts a soil log(PCO₂) of ? 3·47 at AET = 0, and an upper limit of 3·5 per cent (log(PCO₂) = ? 1·45) for mean growing season soil PCO₂ at AET values of 2000 mm and above. The results of this study suggest that soil PCO₂ levels in tropical areas are, on average, higher than those in temperate, alpine, and arctic regions.  相似文献   

Oceanographic Change and Terrestrial Human Impacts in a Post A.D. 1400 Sediment Record from the Southwest Iceland Shelf     

A.E. Jennings  S. Hagen  J. Harðardóttir  R. Stein  A.E.J. Ogilvie  I. Jónsdóttir 《Climatic change》2001,48(1):83-100

Environmental proxies of soil erosion on Iceland, and oceanographic conditions on the adjacent shelf, were measured on a 50 cm box core taken from the southwest Iceland shelf in 1993 during cruise 93030 of the Canadian ship, CSS Hudson. These data, covering the last several centuries, are compared with the documentary record of sea-ice changes around Iceland since A.D. 1600. The site is under the influence of the Irminger Current, which carries warm, saline, Atlantic water northward along the shelf. Because of the relative warmth of this current, sea ice rarely occurs off southwest Iceland, even during the most severe sea-ice intervals of the historical record. In severe sea-ice years, however, the ice drifts clockwise around Iceland from the northeast and east and, in rare cases, reaches the southern coasts (Ogilvie, 1992). The chronology of the core was established by converting the basal radiocarbon date to calendar years and assuming a linear sedimentation rate from the base of the core to the year of collection, 1993. Organic carbon, stable C and O isotope ratios, planktonic foraminiferal assemblages, and sediment magnetic parameters were measured on samples from the core, plotted against calendar years and compared to the Icelandic sea-ice index. The environmental proxies suggest that increased soil erosion, reduced salinity, and, possibly, decreased marine productivity prevailed during the severe sea-ice interval lasting from the last quarter of the eighteenth century to around 1920. Such a situation could develop with climatic cooling, increased storminess, and loss of vegetation cover to stabilise the soil. Although the core site generally lies outside the sea-ice limits, the evidence clearly shows the influence of sea ice and fresh water, and is sensitive to the overall climatic deterioration manifested by the sea-ice record.  相似文献   

江苏省溧水县土壤环境污染预警预测方法探讨   总被引：5，自引：0，他引：5  

范迪富  翁志华金洋潘永敏  周晓明 《江苏地质》2005,29(2):88-93

介绍了溧县土壤环境质量的现状。溧水县主要有黄砂土、栗色土、岗黄土、黄岗土、马肝土、板浆白土、青泥条、青泥土等8种土壤类型。通过地球化学调查和对溧水县土壤的系统采样，获得了反映土壤质量的地球化学数据。通过对土壤中污染物富集历史的研究，揭示了土壤污染物的演化趋势。通过寻找零污染的历史时间结合现代土壤地球化学调查数据，建立了土壤重金属污染预警预测的数学模型。提出了影响土壤质量的关键因子和土壤污染的影响因素，得出了工业是影响土壤质量的主要因子，土壤污染在不断加速的结论。  相似文献   

植被覆盖地表主动微波遥感反演土壤水分算法研究   总被引：5，自引：0，他引：5  

刘万侠  王娟  刘凯  钟凯文 《热带地理》2007,27(5):411-415,450

主动微波遥感监测土壤水分具有全天时、全天候并对地物有一定的穿透能力等特点,突破了传统测量方法和光学遥感获取土壤水分的局限。文中在分析植被对微波信号影响的基础上,总结了当前国内外基于主动微波遥感监测植被覆盖地表土壤水分的原理和方法,指出利用，宋朝景“水-云模型”从总的极化雷达后向散射中去除植被影响后,能够改进后向散射系数和土壤含水量之间的关系。最后利用ENVISAT ASAR数据,结合实地采样获得的土壤含水量数据拟合两者之间的关系,结果表明农作物覆盖地表土壤水分变化的估算算法还需要进一步发展和改进以提高反演精度。  相似文献