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111.
A screening method for heavy metals in aqueous extracts of soil is presented which is based on inhibition of the enzymes urease and alcohol dehydrogenase. The method is suitable to detect cupric and mercury ions in concentrations below 0.01 mg/L and several other heavy metal ions in 1000 fold higher concentration. It is shown that the test may be used for screening of mercury ion concentrations exceeding 0.03 mg/L in aqueous solution when copper chelators are added to the test system. The usefulness of the presented tests to detect heavy metals eluted from soil was verified with samples from ore mining waste. The concentration of copper, lead, and zinc eluted from these samples to different amount was determined by atomic absorption spectrometry and was in good agreement with the enzyme inhibition data obtained with these samples. 相似文献
112.
J. M. Roels 《地球表面变化过程与地形》1985,10(6):587-595
The paper is prompted by apparent deficiencies in the design of plot studies in regional erosion surveys. The principal shortcomings of observational erosion research have been poor sampling design and inadequate analyses of data. The paper identifies various sources of bias which must be taken into account before plot data can be extrapolated to land units in a regional survey. Judging from soil loss data of a case-study in the Ardèche rangelands one may conclude that even accurate plot measurements can still be rather a rough basis for regional erosion assessment. Finally, the paper highlights strategies that might be used to improve erosion sampling. 相似文献
113.
114.
Changes in the rate of soil erosion in lake catchments can be identified from changes in the rate of sediment accumulation in lakes. Here we compare recently afforested sites with non-afforested sites in the Galloway area of Southwest Scotland. We show that lakes with non-afforested catchments have slow, constant sediment accumulation rates, whereas lakes with recently afforested catchments have changes in accumulation that parallel the known history of afforestation. For Loch Grannoch the sediment accumulation rate increases from 0.1 cm yr?1 to over 2 cm yr?2 during the disturbance period. Data from L. Skerrow, however, suggest that the rate might decline to predisturbance levels after approximately 10 years as the forest canopy closes and drainage channels stabilize. 相似文献
115.
J. M. Roels 《地球表面变化过程与地形》1984,9(4):371-381
This paper presents a case study of runoff and sediment generation under Submediterranean rangeland conditions (Ardèche drainage basin, France). Measurements indicate that on a rough hillslope interrill runoff and sediment are not produced uniformly over the slope surface. It is observed that runoff concentrates immediately in non-permanent interrill flow paths, which under average storm conditions vary in length from 1.0 to 12.5 m. Long interrill flow paths may eventually become permanent. These permanent flow paths, called pre-rills, are introduced as a new source area, and are considered to be the initial stage in the development of rills. Along pre-rills considerable quantities of runoff and sediment are carried away. This study also shows that calculations based on interrill, pre-rill, and rill runoff will only have significance if storm and soil conditions are specified in detail. It is concluded from a correlation analysis between the runoff volume and the amount of soil loss on a storm-by-storm basis that the runoff volume alone cannot explain the amount of sediment that is generated in each source area; soil availability is an additional factor that must be taken into account. 相似文献
116.
Th. Verhaegen 《地球表面变化过程与地形》1984,9(6):499-507
Twenty soils from the Leuven region were tested in the laboratory with a rainfall simulator. Their texture varied from loam to loamy sand. On the basis of the results obtained, they were classified as a function of the runoff and splash erodibility. For every soil, several properties were determined and tentatively used to explain the classifications based on the runoff and splash erodibility. Significant negative correlations were found between silt content, aggregate stability, C5–10 index, water content at saturation, and cohesion on the one side and erodibility on the other; a positive correlation was found between sand content and erodibility. 相似文献
117.
118.
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
119.
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
120.
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