Parent Rock Material Research Articles

Pollution caused by metallic fragments introduced into soils because of World War I activities

The influence of parent rock and soil material on the corrosion rate of metallic fragments that remained in soil after World War I in the Soca front area (Slovenia), as well as the corrosion products of these fragments, were studied. The results of corrosion tests did not indicate appreciable differences in corrosion rates between various corrosion media. Consequently, the corrosion rates are influenced mostly by soil aeration, soil humidity and also by microstructures of alloys. Soil type seems to have the most influence on corrosion products. For the pH and Eh ranges that prevail in the studied soils, goethite is the only stable iron mineral. Lead minerals are not stable, and lead, in a Pb2+ cation form, is probably adsorbed onto some minerals – especially goethite – or is bound with organic matter. In distric brown soil, lead stays in the cation form as Pb2+ because of high soil acidity. Cuprite is stable in rendzina and brown soil on limestone, whereas in distric brown soil copper stays in solution as Cu2+.

Neubauer seedling technique to determine availability of nutrient elements for wheat from selected South African soils

The quantity of plant nutrient elements removed from soil by wheat (Triticum aestivum) seedlings were compared with the results of soil tests. Four soils were selected to represent the major parent material and climatic factors responsible for the formation of important agricultural soils in the central eastern Cape Province of South Africa. Acid‐washed sand was used as control. Seedlings were grown for 21 days and nutrient element content in both plant material and soil were determined. Soils derived from dolerite rocks had significantly (P<0.05) higher calcium (Ca), magnesium (Mg), potassium (K), sodium (Na), and phosphorus (P) than those derived from sedimentary rocks. However, iron (Fe), manganese (Mn), and copper (Cu) were higher in soils derived from sedimentary rocks compared to those from dolerite rocks. The differences are attributed to elemental composition of minerals in the two parent rock materials. Within each rock group, soils derived from sites with higher temperature and low rainfall (semi‐arid climate) had significantly (p<0.05) higher nutrient element content than those from sites with lower temperatures and higher rainfall (humid climate). As far as plant growth is concerned, all the soils were well supplied with Ca, Mg, K, Na, and zinc (Zn), but were deficient in P, Fe, and Mn. The trend in uptake of soil nutrient elements by wheat seedlings mirrored their concentration in the soils. Estimates of plant‐available nutrient elements as determined by soil tests and their uptake as determined by tissue concentration were highly correlated for some nutrient elements (r2=0.83, 0.79, 0.94, 0.54, 0.69, and 0.61 for Ca, Mg, K, P, Na, and Zn, respectively) and weak for others (r2=0.47, 0.35, and 0.37 for Fe, Mn, and Cu, respectively). Notwithstanding the shortcomings of extrapolating pot derived results to field conditions, it is concluded that the Neubauer technique may offer a rapid and relatively inexpensive way of relating extractable nutrient elements with plant uptake and growth. Further in country correlation studies are, however, recommended.

Metals and micronutrients – food safety issues

Of all the elements, the most important to consider in terms of food-chain contamination are arsenic (As), cadmium (Cd), mercury (Hg), lead (Pb) and selenium (Se). Where soils are enriched in these elements, it is usually through the agricultural, industrial or urban activities of man, except for Se where high concentrations in soil are often derived from high-Se parent rock materials. The propensity for plants to accumulate and translocate these contaminants to edible and harvested parts depends largely on soil and climatic factors, plant genotype and agronomic management. Elevated As intake, especially of inorganic As, is most likely to arise from high-As drinking water than from ingestion of food. Cadmium and Se are of the greatest concern in terms of terrestrial food-chain contamination, with the former element receiving most attention. Worldwide, the probability of insufficient Se in the human diet exceeds that of toxicity, with deficiency usually associated with monotonous vegetarian diets in areas with Se-deficient soils. Excessive human intake of Cd is of concern as this element accumulates over a lifetime in the body, with impairment of kidney function being the main adverse effect. Cadmium inputs to soil in fertilizer, biosolids, soil amendments and atmospheric deposition often exceed outputs in crops and drainage waters, so that Cd concentrations in many agricultural soils are slowly increasing. However, evidence for increases in Cd concentrations in crops over time is contentious, as is the evidence for human health problems due to low-level Cd contamination of the food chain. Adverse health effects due to Cd intake have been manifest only in situations of gross soil contamination, with a predominantly rice-based diet, where soil–plant and plant–human transfer of Cd would have been enhanced. Human feeding studies have indicated that food Cd bioavailability is dependent on Fe nutrition, and animal studies have indicated that Zn, Ca, P and other elements and food constituents (e.g. fiber, phytate) affect Cd bioavailability. While plant breeding and agronomic management can minimize soil–plant transfer of Cd, and maximize concentrations of antagonists to Cd assimilation in humans, it remains important that inputs of this metal to soil be minimized.

Soil and nutrition status of forest stands under various site conditions of the Moravian-Silesian Beskids

Forest soils of the Moravian-Silesian Beskids are exposed to increasing acidification and podzolization. These conditions developed historically due to climate and parent rock material but also as a result of changes in forest management practices. Recently, acid depositions appear as a crucial factor. Predominating soil types are typical Cambisol or dystric Cambisol, acid or podzol varieties. Soil pH is acid up to very acid with the lowest values in the Oh layer (pH/H 2O 3.5–3.8). pH values of the B horizon range between 3.9 and 4.5. Base saturation of the soils amounts to about 10%. So far conducted studies in the region have not proved the hypothesis on the relationship between the degree of forest stand damage and soil conditions but indicate that the soil conditions can act as a long-term predisposing stress factor particularly when Mg, Ca or N are in deficit.

The Lower Engadine Window: sediment deposition and accretion in relation to the plate-tectonic evolution of the Eastern Alps

The Lower Engadine Window comprises a weakly metamorphosed, heterogeneous mixture of continental fragments and oceanic ophiolites embedded in a disrupted mass of deep-sea sediments ranging from the mid-Jurassic to the Early Eocene, mostly turbidites. Its geological features are reviewed in the light of recent research and its relationships with other Penninic outcrops in the Eastern Alps discussed. In the Falknis, Sulzfluh and Tasna zones it is thought that the entire spectrum of post-Liassic sediments was deposited to the north of the Austro-Alpine continental margin. This is based on downcurrent variations of sedimentary structures to the north or northwest in the same direction as the trend of paleocurrent indicators, and on the close petrographic resemblance of coarse parent rock materials to Austro-Alpine units. Of particular significance are granitic rocks exposed by vertical movements along fault scarps associated with the first formation of oceanic crust. These granitic rocks, together with their Permo-Mesozoic sedimentary cover, were to be eroded and slumped down from the continental margin until the Senonian. Throughout the Jurassic, the clastic sediments were shed laterally onto the abyssal plain and base of the continental slope. Pelagic sedimentation during parts of the Late Jurassic and earliest Cretaceous, including Aptychus limestones deposited close to the calcite compensation depth, suggests that maximum subsidence of the initially passive continental margin had been attained by this time period. With the onset of continental convergence in the earliest Cretaceous, underthrusting of oceanic crust gave rise to an accretionary trench system. The Cretaceous sediments were deposited in a deep-sea fan environment affected by chaotic mass movements from the inner trench wall. It is believed that the close proximity to the source area of the vast majority of Jurassic and Cretaceous deposits reflects the relative motion between the plates, which must have been largely strike-slip and directed essentially E-W during the Cretaceous. An irregular leading edge of the Adriatic plate is proposed to account for Cretaceous high-pressure metamorphic events associated with higher rates of plate consumption in adjacent regions. N-S compressional movements in the Tertiary finally resulted in rapid underthrusting and continental accretion along most of the eastern Alpine arc.

Detection of heavy metals in oak mycorrhizae of northeastern Pennsylvania forests, using x-ray microanalysis

A survey of red and white oak mycorrhizae, using semi-quantitative x-ray microanalysis, has shown a significant difference in heavy-metal deposition between the forest-grown oaks on acidic (mor) and neutral (mull) soils. There are significantly higher levels of nickel, iron, aluminum, and copper within oak roots of Pocono (mor) forests than of Lehigh Valley (mull) forests. The Pocono oak roots were taken from acidic soils derived from sandstone, shales, and conglomerate parent rock materials, while Lehigh Valley oak roots were removed from neutral soils derived from carbonate-rich limestone and dolomite. Chemical analysis of these soils demonstrated higher plant-available heavy-metal content in the acidic soils. Digital line profiles indicated that heavy metals, especially nickel and iron, were concentrated in the peripheral mycorrhizal mantle region of cross-sectioned roots. Since nickel and other heavy metals are known to be toxic to fungi and plant tissues, the high concentrations of metals may be responsible for the decreased frequencies of advantageous ectomycorrhizal associations in oaks growing under certain acid-stressed conditions.

Lateritic soils in environmental management in Nigeria

After a brief introductory discussion on the suitability of various classification systems of lateritic soils for engineering purposes, some geotechnical properties of Nigerian laterites are summarized. These values have been listed separately for soils orginating from the same kind of parent rock material.

Particle size and free iron oxide distribution in some latosols and groundwater laterites of Ghana

The distribution of particle size and Na-dithionite-extractable (di-Fe 2 O 3) and NH 4-oxalate-extractable (ox-Fe 2O 3) iron oxides were investigated in twelve soil profiles representing latosols and groundwater laterites. Soil profiles studied were selected from the major ecological zones of Ghana. The pattern of distribution of free Fe 2O 3 was closely related to that of clay (< 2 μ) in soil profiles of the humid forest zones where clay content was more than 40% in the B horizons. In soil profiles of the relatively dry savannah zones with less than 40% clay in the B horizon, the pattern of distribution of free Fe 2O 3 was closely related to that of silt (2–20 μ). The amount of free Fe 2O 3 in the soils appeared to be related to kind of parent rock or parent material and to climatic factors operating in the various ecological zones. Using the amount of di-Fe 2O 3 in the B horizon as a basis for assessing the relative degrees of pedogenesis in soil profiles developed from the same kind of parent material, it was concluded that soil profile development had progressed most in the rain forest zone. Free Fe 2O 3 was considered as having reached an advanced stage of crystallinity or aging in most of the soils because of the low ox-Fe 2O 3/di-Fe 2O 3 ratios in the solums of most of the soil profiles. Soils studied were placed in the ferrallitic and ferruginous soil classes of D'Hoore. The great soil groups could not be characterized by depth function curves of free Fe 2O 3. However, it was proposed that the relative amounts of di-Fe 2O 3 in the B horizons of the soil profiles could be used as a basis for classifying these soils at the family level.

Vitrification darkening of rock powders: implications for optical properties of the lunar surface

Laboratory experiments show that albedoes as low as those on the Moon can be produced by vacuum vitrification and associated chemical fractionation of ordinary terrestrial basaltic material. Vitrification is established as an unequivocal process that can account for the low albedo and apparent local darkening with age of the lunar surface. The spectral reflectance curves of glass powders are significantly different than those of the parent rock mineralogy; thus, the presence of ubiquitous glass in lunar surface material complicates compositional determinations by interpretation of spectral reflectance curves. Vitrification of rocks on the Moon may highly modify the chemical composition of the resulting glass; thus, glass fragments found in lunar fines cannot be assumed to represent bulk parent rock material. Progressive impact vitrification of lunar surface material throughout the Moon's history may have led to a fine-grain, opaque, refractory-rich material we call ‘ultimate glass’. This unidentified and, at this point, hypothetical component may exist in dark regolith material; if found, it may be a useful indicator of regolith maturity.

Erodibility indices for wildland soils of Oahu, Hawaii, as related to soil forming factors

Soil samples collected along 31 transects in the watersheds of the Koolau and Waianae ranges were analyzed in the laboratory for the size distribution of water‐stable aggregates and suspension per cent. Indices of soil erodibility were related by principal component analyses with varimax rotation to these 7 soil‐forming factors: parent material, rainfall, elevation, vegetation type, slope, aspects, and zone. Parent rock material was the most important factor in explaining variation of water‐stable aggregates of soils in Hawaii. Nevertheless, differences in water‐stable aggregates were also associated with differences in vegetation type and other soil‐forming factors. Most of the soils studied were rated as slightly to moderately erodible under full vegetative cover. The loose condition plus the dispersive and slaking characteristics of volcanic ash soils suggest that they may be twice as erodible as soils of basaltic flow or of the colluvial origin. Among the soil characteristics that serve as indices of erodibility, the suspension per cent was found to be independent of other measures; hence, it may be expected to serve well as a part of an erodibility ratio, such as suspension‐mean weight diameter or a surface‐aggregation ratio. Conversion of the native koa‐ohia scrubby forests by planting paperbark or silk‐oak trees promises to result in development of less erodible soils as well as more useful forest products.

Vertical Petrographic Variability in Annot Sandstone Turbidites: ABSTRACT

A wide range of mineralogical and textural variations was observed between the base and the top of marine Tertiary Annot Sandstone turbidites in the Lac d'Allos region of the French Maritime Alps. This variability may be related to the characteristic vertical distribution of grain sizes and shapes within such graded deposits. Relative percentages of most light and heavy minerals and of the primary matrix, as well as factors of sphericity and roundness, are directly related to grain size. Thus the upward decrease in grain size and increase in grain sorting is reflected in a progressive change in rock composition. Samples (43) were collected at 4-cm intervals between the base and top of four well graded turbidites, each less than one meter thick, and these were compared wit spot samples (125) collected from a 250-m flysch section. The range of petrographic variability within a single turbidite is as great as the range of mineralogic and textural variations between the base and the top of the formation. The same minerals are found in each turbidite, indicating that source areas and eroded parent rock materials accumulated nearshore remained the same during the period of this formation's history. However, notable variations between succeeding turbidites were noted. This may be explained by the fact that each turbidity current is characterized by its own specific density and velocity gradient. As a result, differing proportions of particle sizes settled out of each suspension flow over the same spot on the ocean floor. Even though gravity currents are able to transport identical sedimentary materials from nearshore environments into the deeper basin, such quantitative variations should be expected in any formation composed of turbidites. End_of_Article - Last_Page 371------------

Vertical Petrographic Variability in Annot Sandstone Turbidites: Some Preliminary Observations and Generalizations

ABSTRACT The range of petrographic variability within a single turbidite is approximately as extensive as the range of mineralogical and textural variations observed between the base and top of a 250-m section of Annot Sandstones in the Lac d'Allos region of the French Maritime Alps. The same minerals are found throughout the vertical section of this flysch, indicating that source areas and weathered parent rock materials remained the same during the period of this formation's history. However, notable variations within and between succeeding turbidites are noted. Each suspension flow was characterized by its own specific density and velocity gradient, and, as a result, differing proportions of particle sizes settled out of each current passing over the same spot of the basin floor. Although s cceeding turbidity currents are able to transport similar sedimentary materials from nearshore environments into the deeper basin, quantitative variations of the type observed in this study should be expected in any formation comprising turbidites.

Tree Species Occurrence as Influenced by Geology and Soil on an Ozark North Slope

This study reports an attempt to relate the occurrence of tree species, hence forest types, to soils and surface rock formations in the Ozark Highland of northern Arkansas. The evidence corroborates informal field observations in the region, and suggests that many of the major variations in forest composition and forest site prodluctivity may be explained by soil differences attributable to different parent rock materials. Similar observations have been reported for different rock formations and plant associations in various parts of the country (Owen 1858; Billings 1950; Berkman 1928; Morrow 1931; Cuyler 1931; Read 1950; and others). Lutz and Chandler (1946: 61) have stated: Although there are many references in the literature to the relationship between surface geology and the distribution and growth of forest trees, detailed studies are less common. . . . The best examples [of such relationships] usually occur on relatively immature soils. While the geographic occurrence of the broad zonal groups of soils is determined principally by climate and secondarily by vegetation, the nature of the parent material, in small regions of uniform climate, is probably more important than any other single factor in determining character and productivity of soils (Lutz and Chandler 1946). Because of the diversity of rocks and topographic conditions, and the fact that soils are residual, and because it is a small region of relatively uniform climate, the Ozark Highland provides ample opportunities for studying the influence of geology upon soil formation, and the influence of rocks and soils upon types of vegetation. Several climaxes of permanent, well-marked associations exist in the Ozarks, often contiguous to each other but having originated from different substrata. Steyermark (1940) states that these are not climatic climaxes, as argued by Weaver and Clements (1938), but owe their diversity to the different origin of the soils on which they grow.