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1.
１９８６年和１９９６年两次土壤侵蚀遥感普查的结果表明，辽宁省土壤侵蚀面积减少了１１４８６．９ｋｍ＾２，侵蚀强度呈明显下降趋势，１０ａ间全省轻、中、强各级土壤侵蚀面积分别减少４３５８．７ｋｍ＾２、６２８９．８ｋｍ＾２和３８３８．１ｋｍ＾２。值得得关注的是原来土壤侵蚀较轻的９个市程度不同地出现了强度土壤侵蚀，且有丘陵区强度侵蚀面积减少，低山、中山区增加的趋势。因此，下世纪辽宁水土保持工作的重点是：依法 相似文献
2.
用^137Cs法研究农耕地坡面土壤侵蚀空间分布特征初报 总被引：5，自引：3，他引：5
运用＾１３７Ｃｓ示踪法和网格点采样法对陕北典型的农耕地坡面的土壤侵蚀空间分布特征进行了研究，发现在坡脊和坡沟，随坡长的增长，＾１３７Ｃｓ含量分布呈增加，减少，再增加的波动趋势，而侧坡则呈相反的波动趋势，并利用新的公式计算了农耕地的侵蚀模数。 相似文献
3.
辽宁省应用遥感技术土壤侵蚀普查的研究 总被引：6，自引：0，他引：6
辽宁省是水土流失严重的省份，通过应用遥感技术，对全省进行了土壤侵蚀普查，现查明全省土壤侵蚀面积为５１１６１ｋｍ＾２，占全省总面积的３５．７％，同时利用大量小二水库测淤资源料及径流小区试验资料，推算出全省不同类型区土慢关系模型，并分析辽宁省土壤的动态变化情况以及产生这种变化的原因。 相似文献
4.
低效防护林改造的保土效益 总被引：2，自引：0，他引：2
通过对华蓥山低效防护林改造伯效益观测分析得出;低效防护林改造的保土效益明显。实施改造５年后,由４个径流场测得试验检平均土壤侵蚀模数仅３４．０５６ｔ／ｋｍ＾２。这一数据为合川市平均土壤侵蚀模数的１．３９％,减少了２４１７．９ｔ／ｋｍ＾２。在试验林丰茂的植被条件下,雨强对土壤侵蚀的影响已从首位上退下来,仅为雨量影响的１／６。 相似文献
5.
利用~(137)Cs技术研究土壤可蚀性的时空变异(英文) 总被引：3，自引：0，他引：3
土壤可蚀性的研究变异性是当代土壤侵蚀预测预报研究的核心。本综述了土壤可蚀性变异性研究的进展及存在的问题,提出了利用＾１３７Ｃｓ法定量测定土壤可蚀性时空变异的新技术。 相似文献
6.
利用人工降雨装置，在荒坡和不同郁闭度的天然沙棘林内进行百年－－遇短历时暴雨模拟试验，测得荒坡径流量、土壤侵蚀量分别为３９８６０ｍ＾３／ｋｍ＾３、７３６．６４ｔ／ｋｍ＾２。与荒坡比较，沙棘林有明显的减水减少沙效益，郁闭度越大，减水减沙效益越好，并且当郁闭度大于０．５时，即可有效地控制水土流失。 相似文献
7.
137Cs应用于我国西部风蚀地区土地退化的初步研究─-以新疆库尔勒地区为例 总被引：23，自引：0，他引：23
本文以新疆库尔勒地区为例,首次运用＾１３７Ｃｓ示踪分析法对我国西部风蚀地区土壤侵蚀的强度与区域分布进行了研究,分别计算出该地区荒地,耕地,草地等土地利用类型的土壤侵蚀数平均值为５９８７．２１吨／平方公里;年,３５３７．２９吨／平方公里．年３１７１．３１吨／平方公里．年,其土壤侵蚀强度依次为荒地－耕地－草地。并据此探讨了不同土地利用类型与土地退化之间的相关关系有空间特征。 相似文献
8.
应用智能化遥感信息提取方法对贵阳地区1994年和1998年土壤侵蚀进行了监测试验．研究区面积为2400km2，地理环境复杂。研究内容包括：(1)贵阳土壤侵蚀知识库的建立与检验；(2)土壤侵蚀影响因子的数字化；(3)土壤侵蚀信息提取；(4)土壤侵蚀恶化信息提取；(5)土壤侵蚀危险程度评价。通过研究获得了研究区1994年和1998年的土壤侵蚀情况及其土壤侵蚀恶化情况，分析了土壤侵蚀影响因子的作用程度．在土壤侵蚀恶化信息分析基础上进行了土壤侵蚀危险程度评价。 相似文献
9.
晋东南土石山区降雨侵蚀因子量化研究 总被引：2，自引：0，他引：2
通过对土石山区降雨侵蚀因子的定量研究,得出该区降雨侵蚀的雨量标准是８．６ｍｍ,瞬时雨强公式为：Ｏ＝２．５６６８ｔ＾０．３３８６;降雨侵蚀力最佳组合形式是Ｉ６０ΣＥ或ＰＩ６０;年临界侵蚀模数为１５０ｔ／ｋｍ＾２。该项研究成果为土石山区土壤侵蚀的定量研究和预报工作提供了理论基础和科学依据,并可在同类地区应用和推广。 相似文献
10.
川中小流域丘坡耕地土壤侵蚀研究 总被引：3，自引：0，他引：3
采用放射性元素Ｃｓ－１３７土壤侵蚀调查方法，对川中红壤地区五洞桥小流域丘坡耕地土壤侵蚀进行了研究，揭示了丘陵坡耕地土壤侵蚀特征，推算了不同样点下的年土壤侵蚀模数和侵蚀量，划分了小流域土壤侵蚀强度等级。研究结果为，五洞桥流域年土壤侵蚀总量为５７５６０ｔ，年均土壤侵蚀模数为３５９７ｔ／ｋｍ２，属中度侵蚀区，整个流域可划分为微度侵蚀、轻度侵蚀、中度侵蚀、强度侵蚀等六个侵蚀强度等级。 相似文献
11.
介绍不同类型的同位素的来源,对几种常用的同位素示踪土壤侵蚀的应用做了比较详细的总结。在过去几十年里,人为放射性核素137Cs在土壤侵蚀示踪研究中应用最广泛。同位素210Pb来自于自然界,它在土壤侵蚀中应用的准确度,有待于进一步探讨。宇宙射线产生的放射性核素中,主要介绍7Be在土壤侵蚀研究中的应用。对稳定性稀土元素和几种核素复合示踪土壤侵蚀与泥沙来源研究的国内外研究进展,进行了总结和评价。对应用同位素示踪土壤侵蚀的发展方向,提出了一些看法。 相似文献
12.
Robert E. Sjogren 《Water, air, and soil pollution》1995,81(3-4):315-335
A multiple-antibiotic resistantE. coli was applied to rye-grass covered field mini-plots to simulate point-source contamination. Using three mini-plots for testing and a fourth as a control, the ability of the tracer bacterium to survive under field conditions was studied. Three test plots each received separately 107, 108, or 1010 cfu mL?1 E. coli grown for 24 h. in 5 L one-third strength Tryptic soy broth. In Phase I of the study, it was determined that the tracer disappeared from leaf surfaces of rye-grass covering the plots after 41 days. In Phase II, determination of the presence of the tracer in the top 2″ (5 cm) of soil after two months elapsed time indicated that tracer cfu/g dry wt. of soil had declined five, three, and three-logs for test plots 1,2, and 3. In Phase III, subsurface soil sampling using a soil auger on the three test minei-plots indicated the tracer had penetrated through the top-soil and into the underlying B horizon (20 to 50 cm down). In Phase IV, detailed sampling by excavation of the subsurface soil Horizons of the third test mini-plot showed that the tracer had also penetrated through the hardpan (C Horizon) located 0.6 m below the surface to enter the groundwater (1.06 m deep) (Phase V).E. coli counts fell precipitously to 103 cfu g?1 in soil and then, in the groundwater at the groundwater-soil interface, persisted at a concentration of 103 cfu 100 mL?1 for 2 yr. As time past, tracer counts fell to 145 cfu/100 mL in 6 yr. rose to 820 cfu 100 mL?1 in 1986 (8 yr elapsed time), and then fell to 25 cfu 100 mL?1 in 1991 after 13 yr. Serotyping of 1986E. coli isolates indicated that 62% were of the original tracer serotype (0.128:B12) while only 43% of the 1991 isolates were of the same serotype. The penetration rate of the tracer down through the mini-plot soil into the groundwater was 0.02 m day?1 while downslope dispersion occurred at an estimated rate of 1.0 m day?1. The implications of the above findings are discussed. 相似文献
13.
Wind erosion has degraded over one-half billion hectares of land worldwide. 137Cesium (137Cs) has been used as a tracer to study long-term rates of soil redistribution by water and, to a lesser extent, by wind. Early studies assumed that the decline in 137Cs activity for a potentially eroded soil relative to that for an uneroded soil was linearly proportional to soil loss. More recently, models have emerged that consider the effects of soil cultivation and the particle surface area-dependent partitioning of 137Cs on soils. We investigated the partitioning of 137Cs in wind-eroded sediments and with soil surface samples sieved into contiguous ranges of particle sizes. We also compared the 137Cs activities and stratification of several adjacent soils with known wind erosion and deposition histories. Finally, we tested 137Cs-based soil loss models with measured data from sites with documented histories. 137Cs activities and mean particle diameters of aeolian samples agreed well with the 137Cs activities and respective mean diameters of the sieved surface soil samples. Good agreement between model estimations and measured data indicated that 137Cs models developed to estimate soil redistribution by water were also applicable to soil redistribution by wind provided that the models contained an appropriate particle size correction parameter. 相似文献
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15.
A physically-based dual-porosity model of water and solute transport under transient field conditions was used to simulate3H transport in seven undisturbed monoliths of a coarse-textured sand under bare soil conditions over a period of 15 months. A double-tracer application of3H and36Cl was performed to test whether sidewall flow occurred in this experimental set-up. The objectives of this study were: to identify any impacts of preferential flow in this type of soil, to quantify3H losses from the soil due to evaporation, and to assess the suitability and relative behavior of3H and36Cl as tracers of water. The model input parameter values were obtained by a combination of direct measurements and model calibration. One domain flow simulations of water flow and tracer concentrations in seepage agreed fairly well with those observed, indicating convective-dispersive behavior in this sandy soil. From the observed tracer and water balance for the entire observation period, the recovery of3H and36Cl in seepage was 33 and 91% respectively, with 67% of the applied H lost by evaporation. Both3H and36Cl broke through in seepage simultaneously, showing that36Cl is equally suitable as a tracer of water as3H. The double-tracer test showed that sidewall flow did not occur. 相似文献
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17.
Soil erosion is a serious problem and it is affected by land use and tillage (positive or negative). Even though there are a lot of studies to quantify soil erosion through erosion plots, the models used so far for determination the soil erosion are not well accepted. The purposes of this study were to set up a new erosion quantitative method in determination short-term erosion and sedimentation and to develop spatial erosion distribution models. We chose Eu (europium) as tracer atom. Based on the field experiment, positioning soil core Eu (europium) tracer (PSCET) was established. There were 80 cores set to 8 different slope sections. The samples were taken with soil sampler in 1.5 months interval. We further analyzed the data using multiple linear regressions and multiple linear stepwise regressions to model relationships between soil erosion and its factors. PSCET was applied to bamboo field (Deqing county, southeastern of China). The field was 54 m in length and 15 m in width. The experimental results indicated that erosion modulus increased with gradient increasing and ranged from 83.6 to −53.4 t ha yr−1 in different slope sections. Temporal erosion distribution pattern was consistent with rainfall within a year. The 57.0% of annual rainfall (1068 mm) were accumulated in 3 months (June–August) and 80.1% of the annual soil losses were recorded on bamboo field in 1996–1997 (June–August). The statistical data showed that correlations between erosion modulus with rainfall agent of erosion, slope length, and slope degree index were positive; and with plant cover, organic matter contents, and clay particle contents were negative. Our field experiment results strongly suggest that PSCET makes it possible to study spatial erosion and deposition distributions. 相似文献
18.
Developing a magnetic tracer to study soil erosion 总被引：6，自引：0，他引：6
Soil erosion is commonly measured as the quantity of sediment leaving a plot or watershed. The techniques for measuring soil erosion patterns and sediment redistribution within plots or watersheds by direct monitoring are very limited. The objective of this study was to develop a direct and non-intrusive tracer method to study the sources, patterns and rates of erosion and deposition of sediments in erosion plots. The magnetic tracer developed in this study consisted of polystyrene plastic beads embedded with a magnetic powder (magnetite). The “magnetized” beads, with a mean weight diameter of 3.2 mm and particle density of about 1.2 g cm−3, were uniformly mixed with soil and tested in the laboratory using simulated rainfall and inflow studies to simulate the interrill and rill components of soil erosion, respectively. In the interrill and rill experiments, the tracer was transported in the same proportion it was initially mixed with the soil. Given this fact, a magnetometer, which measures the soil's magnetic susceptibility, could be used to identify areas of deposition or detachment. The magnetic susceptibility would be increased or reduced depending on whether deposition or detachment occurs. To simulate detachment and deposition, a magnetometer was tested for different tracer concentrations and different thickness of soil containing the tracer. The magnetometer promises to be a sensitive, accurate, and useful tool to study the spatial variation of soil erosion when magnetic tracers are used. 相似文献
19.
K.E. Anders Ohlsson 《Soil biology & biochemistry》2011,43(3):675-681
For measurement of the time lag between photosynthesis and CO2 efflux from soil, the carbon isotope pulse-labeling technique is considered as the most suitable. However, an interference from the abiotic tracer CO2 component is identified as a key difficulty for obtaining accurate results with this technique. Guidelines on how to reduce this interference are therefore urgently needed. The flux of abiotic 13CO2 tracer into soil during the labeling stage, and its return to atmosphere during the monitoring stage was modeled numerically, and the labeling stage also analytically. The controls of the abiotic interference were investigated using these models. The amount of the abiotic tracer component and the time distribution of its rate of return to the atmosphere, were predicted by these models. The main model parameters were Dm (=the ratio between the soil 13CO2 diffusivity and the retardation factor), and the 13CO2 concentration at the soil-atmosphere interface during the labeling stage (S13), while background 13CO2 soil production parameters were unnecessary. The presented models guide the selection of experimental parameters for minimization of the abiotic interference. With parameterization for a particular case, the present numerical model provides a preliminary order-of-magnitude estimate of the abiotic component, which would indicate if this interference is of significance. 相似文献
20.
Ralph Meissner Juliane Seeger Holger Rupp Manfred Seyfarth Heinz Borg 《植物养料与土壤学杂志》2007,170(3):335-344
Exact information about soil water flow is needed to quantify solute transfer within the unsaturated zone. Water flux densities are often measured indirectly, e.g., with water‐balance, water content–change, or tracer methods, and, therefore, often predicted with notable uncertainties. Over the last years, direct lysimetry methods have been increasingly used to study water and solute migration in soil profiles. A large weighable lysimeter is the best method to obtain reliable drainage data, but it requires relatively high investment and maintenance expenses. To reduce cost and improve comparability with undisturbed sites, a new technology to collect large monolithic soil columns with a surface area of 0.5–2 m2 and a depth of 1–3 m as well as a containerized polyethylene (PE‐HD) lysimeter station were developed. In addition, the station was fitted with a new high‐precision weighing technique. In this paper, the latter is demonstrated with data from a newly constructed gravitation lysimeter. Besides recording rainfall and seepage, its weighing precision makes it possible to register mass input by dew, fog, or rime. It also permits a very accurate calculation of actual evapotranspiration. Because this new type of lysimeter allows a very high temporal resolution, it is ideally suited to develop and test models for soil hydrologic processes. 相似文献