Soil samples sieving

The soils samples, sieved at 1 mm, were heated at the following temperatures, 124°C, 220°C, 290°C, 350 C, 410°C, 500°C and 600°C to gradually destroy the organic matter and after this treatment they were used directly as catalysts. Soil samples heated at 124°C showed practically no organic matter destruction. Conversely, in those soil samples heated at 600°C almost all the organic matter was destroyed (Table 1). Thus, there is a relationship between... 

Mechanical analyses determine the particle-size distribution in a soil sample. The distribution of coarse particles is determined by sieving, and particles finer than a 200 or 270-mesh sieve and found by sedimentation. 

Perhaps the most serious possibility for error at this stage of the sampling process Is In discarding of vegetation, sod, or other non-soil material collected along with the soil sample as well as the discarding of other materials retained on the sieve. It Is recommended that for approximately 10% of all samples where vegetation, sod, or other non-soil material Is discarded, all discarded material... 

In the laboratory, soil samples collected in the held are mixed thoroughly and reduced in size to laboratory samples. The air-dried soils are passed through a 2-mm sieve in order to remove stones and roots, then the water content of the soil is calculated after drying at 105 °C for 5h. If the analytical samples cannot be analyzed immediately after drying and sieving, they should be stored at about —20 °C in glass or Teflon bottles fltted with screw-caps. 

Air-dried soil samples were screened through a 2-mm sieve, then the water content in the soil was calculated after holding the soil samples for 5h at 105 °C. 

Ultrasonication was reported for the extraction of triazines from soil, previously sieved to 2 mm and stored at -18 °C, prior to analysis using CC/NPD and CC/lTD. A 5-g soil sample was placed in a polypropylene column and extracted for 15 min with 4 mL of ethyl acetate in an ultrasonic bath at room temperature. Subsequently, the solvent was filtered and collected in a graduated tube, and the extraction was repeated for another 15-min period using a second 4-mL portion of ethyl acetate. The two extracts... 

Soil samples are prepared by removing stones and plant materials and passing through a 5-mm sieve. 

In most cases, if soil samples are needed, only surface samples are collected. An exception would be harvesting root crops where all residues in the top 6 in of soil would be sampled. A typical surface soil sampler is shown in Figure 2. It is the residue adsorbed on small particles (<150 o.m), which could cling to moist skin, which causes the most exposure to workers. After sampling, place a flag in the center of each sampled location to mark the area against future sampling. After the surface layer has been collected, the soil is sieved to collect the fraction <150 lam and the remainder of the soil is discarded. Maintain separate sieves and collectors for treated and control plots to prevent contamination of the control samples. 

Soil Drying of soil sample followed by sieving digestion with HN03 centrifugation ICP/AES 0.09 pg/g 97-103 Schmitt et al. 1988... 

Soil samples were sieved to two size fractions <63 pm and <2 mm. Samples were analyzed for multi-element geochemistry by inductively coupled plasma/mass spectrometry (ICP/MS) following a near total 4-acid digestion. 

Soil (L, F, H, and A layers), mosses and fungal fruiting bodies were each collected from the same spots at the three locations. The L, F, H samples were ground to pass a 1 cm sieve the mineral soil was sieved to retain its fine-earth 2mm fraction mosses were separated into green versus dead tissues the fruiting bodies were separated by stalk and cap. Subsamples were freeze-dried prior to... 

There are two sources of biochemicals in soil one is the cellular constituents released when cells are destroyed during the extraction process. It should be kept in mind that any handling of a soil sample will cause the destruction of some of the cells it contains. The simple act of sieving, air drying, and weighing soil will cause some lyses of cells and release of their contents. Extraction will typically cause complete destruction of all cells in soil, with the release of all their constituent parts. Some parts such as enzymes may continue to function after release from the cell and continue to change the makeup of soil components for some time. 

Once dry, the second most common step is to sieve and mix the individual soil sample cores from a single grid. In some cases, samples may need to be... 

Three- to ten-gram soil samples are sieved ( 10 sieve, <2.00 mm) and mixed with sodium sulfate to dry the soil and are paced in an extraction thimble. The thimble is placed in the extraction body of a Soxhlet extraction setup and is extracted with either dichloromethane or dichloromethane/ acetone mixtures for 18 hours (adapted from Reference 6). 

A 1-g sieved, air-dry soil sample is placed in an extraction cell with methanol as a modifier. The sample is extracted at a C02 flow rate of 1.5 mT/min with supercritical carbon dioxide for 15 minutes and analytes trapped in an octadecyl siloxane microextraction disk for subsequent analysis (adapted and condensed from Reference 9). 

As discussed above, after the sample has been collected, a decision has to be taken as to whether the entire sample or a portion of the sample needs to be analyzed. For low-level analytes, the entire sample is often utilized. When the concentration of the analyte is suspected to be well above a detection limit, then a portion of the collected sample can be used. The sample must be homogenous so that the data generated from the subsample are representative of the entire sample. For example, a soil sample may need to be sieved, large pieces ground, and then mixed for the sample to be homogenous. 

Having comminuted the sample it may now be required to carry out a sieving analysis in order to obtain different size fractions for chemical analysis. Fritsch supply a range of devices for sieving analysers (Table 14.2). A practical scheme for sieving a soil sample is discussed below. 

To perform a hydrometer test for a soil sample, a known mass of sieved (<2 mm) soil is thoroughly mixed with a dispersing agent. It is then placed in a graduated cylinder, water is added, and the mixture is carefully agitated. A hydrometer is carefully placed in the mixture and read at 2 min, 12 min, and after 24 h. 

Soil samples were wet sieved into (a) 2-4 mm, (b) 1-2 mm, (c) 0.5-1 mm, (d) 250-500 i m, (e) 125-250 am, (f) 63-125 j,m and (g) <63 j.m fractions. A ferruginous/magnetic fraction (m) was also prepared from the 2-4 mm fraction. Soil fractions were crushed, digested with HNO3/HCI/HF/HCIO4 and then analysed by Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES) for Al, Ca, Cu, Fe, K, Mn, Na, P, S and Zn. Inductively Coupled Plasma Mass Spectrometry (ICP-MS) was used to determine Ag, As, Cd, Pb and Sb because of the lower detection limits by this method. The mineralogy of selected samples was determined by qualitative X-ray diffractometry. 

A total of 80 soil samples and 30 stream sediment samples were collected in the vicinity of known mineralization and analyzed for 36 elements in four size fractions. Orientation results indicate that soil samples should be collected from the near-surface soil horizon on a 100 by 200 m grid pattern, and sieved to the coarse, -8+35 mesh fraction prior to analysis. Stream sediment samples should be collected at a sample density of approximately 1 sample per 1 km and sieved to the fine, -150 mesh fraction. As expected, copper and molybdenum show the strongest response to copper-molybdenum mineralization at both Pico Prieto and Venado in addition, the following elements are also associated with mineralization at Tameapa Au, Ag, Pb, Zn, V, W, Ni, As, Sb, Bi, Se, Sr, and Ba. 

All soil samples were sieved into four size fractions and analyzed for 36 elements by aqua regia digestion/ICP-MS finish. The size fractions included a coarse size (-8+35 mesh), a medium size (-35+80 mesh), a fine size (-80+150 mesh), and a very fine size (-150 mesh). The coarse and medium size fractions were pulverized to 70% passing 150 mesh prior... 

Source Materials. Two categories of local source materials were sampled - road dust and soil. Samples of bulk soil were removed from the upper 10 cm of the soil column at 74 locations over portions of the 1 km centered on the ground site. A square grid spacing of 160 m (0.10 mi) between sampling locations was used. Before analysis, the samples were air dried, crushed, and sieved to remove the larger particles (>53 pm diameter) which would not be likely to be raised by the wind. 

The sample preparation procedure for dry sieved stream sediment samples is presented inFig. 13. The preparation procedures for floodplain sediment and soil samples are presented in Figures 14 and 15, respectively. 

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