The effect of sample grinding on extractable iron and aluminum in soils

1993 ◽  
Vol 73 (1) ◽  
pp. 73-80 ◽  
Author(s):  
A. J. Neary ◽  
S. R. Barnes
Keyword(s):  
Ammonium Oxalate ◽  
Sandy Soils ◽  
Mesh Size ◽  
Soil Samples ◽  
Homogeneous Sample ◽  
Iron Aluminum ◽  
Sieve Mesh Size ◽  
Key Words Iron ◽  
Extractable Iron ◽  
Primary Minerals

Pyrophosphate-, dithionite- and acid ammonium oxalate-extractable Fe and Al are often measured on a finely ground aliquot of soil. Grinding provides a homogeneous sample from which a representative subsample can be obtained at sampling aliquots of less than 1 g. When a significant portion of the unground soil is greater than the sieve mesh size used when grinding, abrasion of primary minerals may cause increased levels of extractable Fe and Al. This study examined the distribution of extractable Fe and Al in some sandy soils and compared their levels in samples ground to < 500 μm and < 150 μm with those in unground < 2-mm soil. Samples ground to < 150 μm yielded the highest amounts of extractable Fe and Al. This effect was most prevalent when a motorized mortar and pestle was used. Samples ground to < 500 μm, which were frequently re-sieved to avoid over-grinding, contained similar amounts of extractable Fe and Al as the unground < 2-mm sample. If less than 1 g of soil is used for analysis, a sample manually ground to < 500 μm (35 mesh) is advisable and a protocol for sample grinding is recommended. Key words: Iron, aluminum, pyrophosphate, dithionite, oxalate, grinding

Magnetic susceptibility of Gleysolic and Chernozemic soils in Saskatchewan

2002 ◽  
Vol 82 (2) ◽  
pp. 191-199 ◽  
Author(s):  
E. de Jong
Keyword(s):  
Magnetic Susceptibility ◽  
Key Words ◽  
Soil Samples ◽  
Sand Content ◽  
Poorly Drained Soils ◽  
Extractable Iron

In Saskatchewan, Gleysolic and Chernozemic soils often are found close to each other in hummocky terrain. Magnetic susceptibility (χ) is known to be reduced in poorly drained soils compared to well-drained soils, and this study investigated the use of χ as an accessory criterion for identifying Gleysols. Archived soil samples from an area near Saskatoon were analyzed for χ and sand content, and where necessary for organic and inorganic C and oxalate (Feo) and dithionite (Fed) extractable iron. The lowest χ values were found in Humic Luvic Gleysols and the highest in Dark Brown Chernozems; Rego and Orthic Gleysols and Rego Humic Gleysols had χ values that overlapped those of the Dark Brown Chernozems. Within the upper 50 cm of the profile, all Gleysols except the Rego Humic Gleysol had at least one horizon with %chi; less than 150 × 10-9m3kg-1. The χ of the A and B horizons was negatively correlated to their Feo/Fed ratios, and not correlated to their sand content. The χ of the deep tills was positively correlated to sand content, and not correlated to Feo/Fed ratio. It appears that χ may be as useful as the Feo/Fed ratio for assisting in classifying Gleysols. Key words: Magnetic susceptibility, Gleysols, Chernozems, Feo, Fed, CaCo3

SESQUIOXIDE-CEMENTED SOIL HORIZONS IN NORTHERN QUEBEC: THEIR DISTRIBUTION, PROPERTIES AND GENESIS

1976 ◽  
Vol 56 (4) ◽  
pp. 333-344 ◽  
Author(s):  
T. R. MOORE
Keyword(s):  
Organic Matter ◽  
Classification System ◽  
Soil Horizons ◽  
Amorphous Iron ◽  
Far North ◽  
Cemented Soil ◽  
North Shore ◽  
Iron Aluminum ◽  
Extractable Iron

Cemented subsoil horizons are observed in soils along the St. Lawrence North Shore, as far north as Esker. Cementation is mostly strongly developed at depths of 30–90 cm in freely drained soils of sand texture containing large amounts of amphibole minerals. The cemented horizons contain generally small quantities of extractable iron, aluminum and organic matter, though larger than their non-cemented counterparts. A slaking experiment indicates that amorphous iron and aluminum are the main cementing agents. Three hypotheses for the genesis of these cemented horizons are examined; it is proposed that iron and aluminum are released in the Ae horizon, translocated in a basically inorganic form, and precipitated in the B horizons as cementing agents. Study of a chronosequence of soils suggests that 5,000–6,000 yr are required for the formation of strong cementation. The new chemical criteria established for the Podzolic Order of the Canadian Classification System work well in these soils.

Macrobenthic community structure in tropical estuaries: the effect of sieve mesh-size and sampling depth on estimated abundance, biomass and composition

2013 ◽  
Vol 93 (6) ◽  
pp. 1441-1456 ◽  
Author(s):  
Ana Paula Maria Cavalcanti Valença ◽  
Paulo Jorge Parreira dos Santos
Keyword(s):  
Community Structure ◽  
Mesh Size ◽  
Environmental Parameters ◽  
Total Biomass ◽  
Sampling Depth ◽  
Total N ◽  
The Status ◽  
Sieve Mesh Size ◽  
The Difference ◽  
Sampling Procedures

Macrobenthic data from estuaries along the Pernambuco coast in north-eastern Brazil were analysed to evaluate the effect of sieve mesh size (1.0 mm × 0.5 mm) and sampling depth (0–10 cm × 0–20 cm) on the description of infaunal communities, in an attempt to discuss standardized sampling procedures for different ecological studies objectives in these ecosystems. In general, the difference in sieve retention was less evident for biomass but was important for abundance: the 1.0 mm sieve retained only 27% of total individuals but 77% of total biomass. Regarding sampling depth, the 0–10 cm layer contained most individuals (94%) but contributed just 64% of the overall biomass. Although no strong differences in community structure were observed at most sites with the use of different sieves, the correlations among community dissimilarity using different meshes with environmental parameters (organic matter, total-N and microphytobenthos) indicated that the use of the 0.5 mm sieve will allow a better evaluation of the status of these estuaries. The results also highlight the importance of taking the vertical distribution of tropical macrofauna into account for quantitative estimates: for taxa composition and abundance the top layer is clearly essential, whereas for biomass the deeper layers should also be considered.

Sieve mesh size and quantitative chironomid paleoclimatology

2007 ◽  
Vol 38 (3) ◽  
pp. 329-345 ◽  
Author(s):  
Dirk Verschuren ◽  
Hilde Eggermont
Keyword(s):  
Mesh Size ◽  
Sieve Mesh Size

EFFECT OF IRON ON THE NATURE OF PRECIPITATION PRODUCTS OF ALUMINUM

1987 ◽  
Vol 67 (1) ◽  
pp. 135-145 ◽  
Author(s):  
TEE BOON GOH ◽  
M. J. DUDAS ◽  
S. PAWLUK ◽  
P. M. HUANG
Keyword(s):  
Molar Ratio ◽  
Ambient Conditions ◽  
Crystalline Materials ◽  
Molar Ratios ◽  
Iron Aluminum ◽  
Initial Ph ◽  
Oxide Phases ◽  
Key Words Iron ◽  
Rate Of Hydrolysis ◽  
Mixed Systems

Solutions Of AlCl3 (5 × 10−3 mol L−1) and FeCl2 were mixed and aged for 3 yr under ambient conditions at the initial pH of 7.0 and Fe:Al molar ratios of 0, 0.1, 0.3, 0.5 and ∞ (Fe at 5 × 10−3 mol L−1). Fe2+ was readily oxidized in this experiment so that only the mutual interaction between Fe3+ and Al3+ can be reported. The initial Fe:Al molar ratio was an important parameter in determining the rate and amount of hydrolysis and precipitation of Fe and Al. At Fe:Al molar ratios ≤ 0.3, hydrolysis was delayed when compared to that in pure Al suspensions. At higher ratios more acidity was produced by hydrolytic reactions. The acidity was contributed by both Al and Fe. The fractions of Fe and Al precipitated were greater at lower Fe:Al molar ratios. Aluminum and iron were mutually interfering cations during crystallization. In mixed systems, the fractions of crystalline materials were greatly reduced. Between the crystalline compounds, gibbsite was more abundant than bayerite and this evolution was governed by pH and the interference of Fe on the subsequent rate of hydrolysis and crystallization. Iron substitution was not evident in the crystalline Al(OH)3 polymorphs. Crystalline Fe oxides could not be detected even at the Fe: Al molar ratio of 0.1. Two discrete oxide phases were formed in the mixed Fe-Al systems consisting of crystalline Al(OH)3 and a mixed Fe-Al oxide of indeterminate composition. In the pure ferric suspension, maghemite was formed. The results presented are used to explain the distribution of aluminum hydroxide polymorphs in soil and the genesis of gibbsite and iron oxide containing horizons of Oxisols. Key words: Iron, aluminum, gibbsite, bayerite, maghemite, Fe-Al surface coatings

Water repellency under natural conditions in sandy soils of southern Spain

Soil Research ◽  
2005 ◽  
Vol 43 (3) ◽  
pp. 291 ◽  
Author(s):  
Francisco J. Moral Garcíía ◽  
Louis W. Dekker ◽  
Klaas Oostindie ◽  
Coen J. Ritsema
Keyword(s):  
Organic Matter Content ◽  
Sandy Soils ◽  
Water Repellency ◽  
Matter Content ◽  
Soil Samples ◽  
Southern Spain ◽  
Natural Conditions ◽  
Soil Water Repellency ◽  
Natural Park ◽  
Naturally Occurring

The occurrence and consequences of fire-induced water repellency have been studied in several regions of Spain since 1989. The occurrence of water repellency formed under natural conditions, however, has only been described for a few areas in Spain since 1998. The purpose of the present study was to investigate the severity of naturally occurring water repellency in the sandy soils of the Natural Park of Doñana in southern Spain. The persistence and degree of soil water repellency were measured on field-moist and dried sandy soil samples taken beneath Pinus pinea trees. Around 50% of the field-moist soil samples taken at 0–0.10 m depths exhibited (actual) water repellency. Potential water repellency, measured after drying the samples at 60°C, showed for 68% of the samples slight to extreme water repellency. The organic matter content was found to be positively correlated with persistence and with degree of potential water repellency.

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