Residual soil

There are areas (22) where selenium levels in the soil are very low these include regions of volcanic activity like that adjacent to the Cascade mountains in the Pacific Northwest states of the United States and the central north island of New Zealand. There, because the heat of emption volatilized the selenium, the residual soil parent material is virtually devoid of selenium. Other areas of low soil-selenium reflect leaching of selenium out of the top soil, as in the Canterbury plain on New Zealand s south island. Areas of selenium deficiency have negative implications for animal and human health. 

More objective laboratory methods employ a mechanical device such as a Terg-O-Tometer (110). Food soils are appHed to microscope sHdes or glass tape rather than to actual plates. The soils are tagged with fluorescent materials or with dark pigment to faciUtate measurement of residual soil. Reflectance or transmittance may also be read directly (111). 

When a quantitative estimate of residual soil is not called for and the suitabiUty of a metal surface for further finishing needs to be assessed, the water-break test is used. The term water-break refers to the behavior of a water film on a smooth greasy surface. When the film becomes sufficiently thin by drainage, it suddenly breaks into islands or droplets between which the surface appears dry. On the other hand, when a film drains from a clean water-wettable, nongreasy surface, it becomes progressively thinner and finally disappears by evaporation without ever breaking into droplets. Such a surface is said to be free from water-break. 

Where easily weathered lithologies such as carbonates and evaporites are near the surface, such as in the lower Amazon valley, their contribution to the rivers appears minor, probably because thick residual soil covers have devel-... 

J. N. Ladd, M. Amato, P. R. Grace, and J. A. Van Veen, Simulation of turnover through the microbial biomas.s in soils incubated with C-labelled residues. Soil Biol. Biochem. 27111 (1995). 

N. Watkins, and D. Barraclough, Gross rates of N mineralization associated with the decomposition of plant residues. Soil Biol. Biochem. 2S 5169 (1996). 

Dislodgeable soil residue (DSR) studies are used to determine exposure of re-entry workers to soil surface residues. Soil surface residues are defined as test substance residue levels in <150-q.m soil particles (i.e. soil dust which can stick to a worker s skin, or can be inhaled). 

The facility would use a dry scrubber system for emission control, which would eliminate the need for wastewater treatment. Any water from emission control and from decontamination procedures would be treated in the on-site groundwater treatment system. The residual soil and collected ash is assumed to be nonhazardous and can be disposed of in a solid waste disposal facility in compliance with subtitle D of RCRA. In the event that they cannot be delisted due to the presence of metals, the residuals will be managed as part of the closure of Area 2 shown in Figure 16.21 (lead-contaminated soil). 

Almendros G, Gudalix G, Gonzalez-Vila F, Martin F (1998) Distribution of structural units in humic substances as revealed by multi-step selective degradations and C-13 NMR of successive residues. Soil Biol Biochem 30 755-765... 

Despite its humorous name, this technology is a fairly efficient procedure to combine the benefits of vacuum-enhanced recovery and bioventing to promote vapor recovery and in situ biodegradation. Integration of these technologies into a single step results in LNAPL recovery and remediation of residual soil contamination in the vadose zone. 

Many conventional soil vashing processes are based on the principle that pollutants adsorb onto very small particles fine fractions of the soil such as silt, clay and humic matter ivhich tend to be attached to coarser sand and gravel particles. These larger particles make up the majority of the soil content. A primary aim in soil washing is therefore to dislodge and separate these fine components from the bulk soil. If the pollutant materials can be detached from the bulk, possibly together with some other surface contamination, a concentrated volume of polluted soil can be produced. This can then be treated or disposed of and a large volume of residual soil which requires relatively little treatment and can be returned to the site as back fill. 

As a regional observation, arsenic is concentrated in the >1 mm soil fraction, and defines broad-scale anomalies in areas of shallow bedrock or residual soil. It has probably been adsorbed onto amorphous secondary Fe oxides, some of which have formed pisoliths. By contrast, Au is generally concentrated in the claysized fraction of transported soils. 

Approximately 3 kg of soil was collected from 0-15 cm at 4 sites in the Endeavor Mine area. Background residual soils... 

Surficial soils developed upon transported material (Bengaccah) have <1% coarse material (>2 mm) and about 50% finer than 63 pm whereas the residual soils tend to have several percent coarse material and <40% fine material. Quartz in soils in transported material (Bengaccah) also tends to be more rounded than elsewhere. 

The difficulty in allelopathic studies has been to link the allelochemicals directly with the plant growth problems. Before the role of crop residue, soil management, or other practices in allelopathic problems can be evaluated, a direct link must be established between the source or production of the chemicals and plant damage. Plant damage may be caused by the chemicals produced from residue decomposition or from the microorganisms residing in the residues. 

An assessment of the rates and duration of phenolic acid production from a residue is an important first step. Laboratory and field studies for assessing the dynamics of phenolic acid production must include considerations of the nature of the residue, soil properties, nutrient status of the system, microbial biomass interrelationships, temperature, moisture, residue placement in or on the soil, and other factors that relate to the field. Soil properties in the field are especially important when organic residues are incorporated. When soils are wet, such as those with more than -0.02 MPa water potential, oxygen diffusion is impeded and anaerobic conditions prevail, especially in soils that are high in clay content. Under these circumstances, microbial byproducts change dramatically and one result, for example, is an increase in the production of phenolic acids. Phenolic acid production is also affected by temperature (22) and soil fertility status (23). While the C H ratio of an organic residue may influence the rate of its decomposition and, hence, the rate of phenolic acid production, the... 

Stream sediment (mineral sediment, <0.150 mm) Residual soil, upper horizon (topsoil) 0 - 25 cm with out the top organic layer (<2 mm)... 

Residual soil, lower (C) horizon (subsoil) a 25 cm layer within a depth range of 50 cm - 200 cm (<2 mm) Humus where present... 

Baltic Soil Survey Those countries which have taken part in the Baltic Soil Survey (BSS) can use the BSS soil samples in the FOREGS mapping. If you want to do so, please use the randomly selected points provided by the GSF to select the nearest BSS sampling site. The stream sediment, stream water and optional overhank sediment samples should be taken from the same small catchment and the floodplain sediment from the adjacent large drainage basin. You can decide whether you want to use the BSS samples or take new residual soil samples. If you use a BSS sample, mark it on the field observation sheet. 

Stream water Stream sediment (mineral sediment) Residual soil, upper horizon (topsoil) 0 - 25 cm without organic layer Residual soil, lower (C) horizon (subsoil) a 25 cm layer within a depth range of 50 cm - 200 cm Soil samples should represent the dominant soil type of the small catchment. W s T C... 

Residual and sedentary soils Residual soil is collected from the small, second order, drainage basin (< 100 km2) at a suitable site above its alluvial plain and base of slope, where alluvium and colluvium are respectively deposited. The residual soil may be developed either directly on bedrock or on till, as is the case in glaciated terrains. Residual soil distributed by agricultural activities should be avoided where possible since the top soil is usually affected by human activities. It is important to ensure that the material collected is residual and not transported material such as coluvium or alluvium. 

Colour photographs must be taken at all sampling sites (stream water and sediment, residual soil, humus, floodplain sediment and optional overbank sediment), and recorded on the field observation sheets. Each photograph, after processing, should be carefully labelled at the back with a fine permanent ink and sent to the co-ordinator (Geological Survey of Finland) upon completion of the sampling. 

Photographs of the water/stream sediment sample site could be taken before or after the sampling. Organic layer (humus), residual soil pits, floodplain and overbank sediment pits must be photographed before taking the sample fill-in flash should normally... 

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