Characteristics and Origin of Rock Varnish from the Hyperarid Coastal Deserts of Northern Peru

1991 ◽  
Vol 35 (1) ◽  
pp. 116-129 ◽  
Author(s):  
Charles E. Jones
Keyword(s):  
Clay Minerals ◽  
Laboratory Experiments ◽  
Soil Samples ◽  
Alkaline Soils ◽  
Rock Varnish ◽  
New Type ◽  
Northern Peru ◽  
Fe Oxyhydroxides ◽  
Mn Content

AbstractThe characteristics of a new type of rock varnish from the hyperarid coastal deserts of northern Peru, combined with laboratory experiments on associated soil materials, provide new insights into the formation of rock varnish. The Peruvian varnish consists of an Fe-rich, Mn-poor component covering up to 95% of a varnished surface and a Fe-rich, Mn-rich component found only in pits and along cracks and ridges. The alkaline soils plus the catalytic Fe oxyhydroxides that coat much of the varnish surfaces make the Peruvian situation ideal for physicochemical precipitation of Mn. However, the low Mn content of the dominant Fe-rich, Mn-poor component suggests that such precipitation is minor. This, plus the presence of abundant bacteria in the Mn-rich varnish and the recorded presence of Mn-precipitating bacteria in varnish elsewhere, suggests that bacteria are almost solely responsible for Mn-precipitation in rock varnish. A set of experiments involving Peruvian soil samples in contact with water-CO2 solutions indicates that natural fogs or dews release Mn but not Fe when they come in contact with eolian materials on rock surfaces. This mechanism may efficiently provide Mn to bacteria on varnishing surfaces. The lack of Fe in solution suggests that a large but unknown proportion of Fe in varnish may be in the form of insoluble Fe oxyhydroxides sorbed onto the clay minerals that form the bulk of rock varnish. The results of this study do not substantively change R. I. Dorn's paleoenvironmental interpretations of varnish Mn:Fe ratios, but they do suggest areas for further inquiry.

scholarly journals Re-evaluation of manganese solubility as affected by soil sample preparation in the laboratory

2005 ◽  
Vol 48 (4) ◽  
pp. 643-646 ◽  
Author(s):  
Emilene Andrade ◽  
Mário Miyazawa ◽  
Marcos Antonio Pavan ◽  
Edson Lima de Oliveira
Keyword(s):  
Soil Sample ◽  
Laboratory Experiments ◽  
Soil Analysis ◽  
Field Capacity ◽  
Soil Samples ◽  
Soil Types ◽  
Test Plant ◽  
Soil Processes ◽  
Maize Seedlings ◽  
Mn Content

Laboratory experiments were conducted to re-evaluate the effects of drying and the time between drying and Mn analysis on soil Mn solubility using maize seedlings as test plant. Samples of five soil types were collected in the field, transferred to laboratory and submitted for the following treatments: dried in the shade at 25ºC and dried at 65ºC followed by Mn determination immediately and after 30 and 60 days. Ninety days later soil samples were rewetted at field capacity and maize seedlings were grown for 7 days. Evaluations included plant Mn content and soil Mn extracted with NH4OAc 1 mol L-1 pH 7. The lowest soil and plant Mn contents were found in soil samples dried in the shade at 25ºC. Drying soil sample at 65ºC and increasing the time between drying and Mn analysis increased Mn solubility and Mn uptake by maize. Oxisols showed higher soil and plant Mn contents than other soil types. The results indicated the extreme difficulty in interpreting soil Mn results due to the great effect of soil processes in the laboratory on Mn solubility. Routine soil analysis is not recommended to evaluate plant available Mn.

scholarly journals Effect of pedogenic iron-oxyhydroxide removal on the metal sorption by soil clay minerals

2021 ◽  
Vol 21 (4) ◽  
pp. 1785-1799
Author(s):  
Péter Sipos ◽  
Viktória Kovács Kis ◽  
Réka Balázs ◽  
Adrienn Tóth ◽  
Tibor Németh
Keyword(s):  
Clay Minerals ◽  
Close Association ◽  
Direct Analysis ◽  
Alkaline Soil ◽  
Mineral Surfaces ◽  
Iron Oxyhydroxide ◽  
Metal Sorption ◽  
Before And After ◽  
Fe Oxyhydroxides ◽  
Cu And Zn

Abstract Purpose The close association of Fe-oxyhydroxides and clay minerals might influence the sorption properties of these components. We aimed to study the effect of removing the pedogenic Fe-oxyhydroxides on the sorption of Cd, Cu, Pb, and Zn by the clay mineral particles in soils with contrasting pH. Methods Competitive batch sorption experiments before and after Fe-oxyhydroxide extraction in soils were carried out together with the direct analysis of the metal sorption on individual particles of ferrihydrite, smectite, and illite/smectite by TEM. Results Ferrihydrite was a more effective metal sorbent than clay minerals, although its removal resulted in decreased sorption only for Cd, Cu, and Zn. Ferrhydrite coating blocked metals’ access for certain sorption sites on clay surfaces, which were only accessible for Pb as the most efficient competitor after removing the coating. This observation was the most remarkable for the smectite particles in the alkaline soil. Mineral surfaces sorbed higher Cu than Pb concentrations and higher Zn than Cd concentrations despite the former metals’ lower bulk sorption. Thus, organic surfaces and precipitation contributed to Pb and Cd’s retention to a greater extent than for Cu and Zn. The structural Fe of smectite also promoted the metal sorption in both soils. Conclusion Removal of iron-oxyhydroxide coatings from the soil affects metal sorption selectively. Direct study of metal sorption on individual soil particles enables us to gain a more in-depth insight into soil minerals’ role in this process.

scholarly journals Sorption and Desorption of Vanadate, Arsenate and Chromate by Two Volcanic Soils of Equatorial Africa

Soil Systems ◽  
2021 ◽  
Vol 5 (2) ◽  
pp. 22
Author(s):  
Sara Gonzalez-Rodriguez ◽  
Maria Luisa Fernandez-Marcos
Keyword(s):  
Laboratory Experiments ◽  
Sorption Isotherms ◽  
Soil Samples ◽  
Mineral Surfaces ◽  
Volcanic Soils ◽  
Iron Species ◽  
Freundlich Model ◽  
Equatorial Africa ◽  
Relevant Role ◽  
Icp Mass Spectrometry

Sorption of oxyanions by soils and mineral surfaces is of interest due to their role as nutrients or pollutants. Volcanic soils are variable charge soils, rich in active forms of aluminum and iron, and capable of sorbing anions. Sorption and desorption of vanadate, arsenate, and chromate by two African andosols was studied in laboratory experiments. Sorption isotherms were determined by equilibrating at 293 K soil samples with oxyanion solutions of concentrations between 0 and 100 mg L−1 V, As, or Cr, equivalent to 0−2.0 mmol V L−1, 0−1.3 mmol As L−1, and 0−1.9 mmol Cr L−1, in NaNO3; V, As, or Cr were determined by ICP-mass spectrometry in the equilibrium solution. After sorption, the soil samples were equilibrated with 0.02 M NaNO3 to study desorption. The isotherms were adjusted to mathematical models. After desorption with NaNO3, desorption experiments were carried out with a 1 mM phosphate. The sorption of vanadate and arsenate was greater than 90% of the amount added, while the chromate sorption was much lower (19–97%). The sorption by the Silandic Andosol is attributed to non-crystalline Fe and Al, while in the Vitric Andosol, crystalline iron species play a relevant role. The V and Cr sorption isotherms fitted to the Freundlich model, while the As sorption isotherms conformed to the Temkin model. For the highest concentrations of oxyanions in the equilibrating solution, the sorbed concentrations were 37–38 mmol V kg−1, 25 mmol As kg−1, and 7.2–8.8 mmol Cr kg−1. The desorption was low for V and As and high for Cr. The comparison of the sorption and desorption isotherms reveals a pronounced hysteresis for V in both andosols and for Cr in the Silandic Andosol. Phosphate induced almost no V desorption, moderate As desorption, and considerable Cr desorption.

scholarly journals Archaeal Communities in a Heterogeneous Hypersaline-Alkaline Soil

Archaea ◽  
2015 ◽  
Vol 2015 ◽  
pp. 1-11 ◽  
Author(s):  
Yendi E. Navarro-Noya ◽  
César Valenzuela-Encinas ◽  
Alonso Sandoval-Yuriar ◽  
Norma G. Jiménez-Bueno ◽  
Rodolfo Marsch ◽  
...  
Keyword(s):  
Species Richness ◽  
Alpha Diversity ◽  
Methanogenic Archaea ◽  
Archaeal Community ◽  
Soil Samples ◽  
Alkaline Soil ◽  
Alkaline Soils ◽  
Phylogenetic Information ◽  
Archaeal Communities ◽  
Saline Alkaline Soils

In this study the archaeal communities in extreme saline-alkaline soils of the former lake Texcoco, Mexico, with electrolytic conductivities (EC) ranging from 0.7 to 157.2 dS/m and pH from 8.5 to 10.5 were explored. Archaeal communities in the 0.7 dS/m pH 8.5 soil had the lowest alpha diversity values and were dominated by a limited number of phylotypes belonging to the mesophilic CandidatusNitrososphaera. Diversity and species richness were higher in the soils with EC between 9.0 and 157.2 dS/m. The majority of OTUs detected in the hypersaline soil were members of the Halobacteriaceae family. Novel phylogenetic branches in the Halobacteriales class were detected in the soil, and more abundantly in soil with the higher pH (10.5), indicating that unknown and uncharacterized Archaea can be found in this soil. Thirteen different genera of the Halobacteriaceae family were identified and were distributed differently between the soils.Halobiforma,Halostagnicola,Haloterrigena, andNatronomonaswere found in all soil samples. Methanogenic archaea were found only in soil with pH between 10.0 and 10.3. Retrieved methanogenic archaea belonged to the Methanosarcinales and Methanomicrobiales orders. The comparison of the archaeal community structures considering phylogenetic information (UniFrac distances) clearly clustered the communities by pH.

EFFECTS OF LIME ON EXTRACTABLE ALUMINUM AND OTHER SOIL PROPERTIES AND ON BARLEY AND ALFALFA GROWN IN POT TESTS

1972 ◽  
Vol 52 (3) ◽  
pp. 427-438 ◽  
Author(s):  
A. J. MacLEAN ◽  
R. L. HALSTEAD ◽  
B. J. FINN
Keyword(s):  
Plant Growth ◽  
Soil Properties ◽  
Soil Ph ◽  
Acid Soil ◽  
Soil Samples ◽  
Neutral Salt ◽  
Incubation Experiment ◽  
Pot Experiments ◽  
P Content ◽  
Mn Content

Liming of six acid soil samples in an incubation experiment with rates to raise the soil pH to 6.0 or above eliminated Al soluble in 0.01 M CaCl2, reduced soluble Mn and Zn, increased NO3-N markedly, and at the highest pH increased the amounts of NaHCO3-soluble P in some of the soils. In corresponding pot experiments, liming increased the yield of alfalfa and in three of the soils the yield of barley also. Liming reduced the concentrations of the metals in the plants and at the highest pH tended to increase the P content of the plants. Liming to a pH of about 5.3 eliminated or greatly reduced soluble Al and the soils were base saturated as measured by the replacement of Al, Ca, and Mg by a neutral salt. There was some evidence that liming to reduce soluble Al and possibly Mn was beneficial for plant growth. Gypsum increased the concentrations of Al, Mn, and Zn in 0.01 M CaCl2 extracts of the soils whereas phosphate reduced them. The changes in the Mn content of the plants following these treatments were in agreement with the amounts of Mn in the CaCl2 extracts.

scholarly journals A Hooked-Collar for Bridge Piers Protection: Flow Fields and Scour

Water ◽  
2018 ◽  
Vol 10 (9) ◽  
pp. 1251 ◽  
Author(s):  
Su-Chin Chen ◽  
Samkele Tfwala ◽  
Tsung-Yuan Wu ◽  
Hsun-Chuan Chan ◽  
Hsien-Ter Chou
Keyword(s):  
Laboratory Experiments ◽  
Horseshoe Vortex ◽  
Flow Fields ◽  
Bridge Pier ◽  
The Other ◽  
Bridge Piers ◽  
Vortex Strength ◽  
Numerical Tests ◽  
Scour Hole ◽  
New Type

A new type of collar, the hooked-collar, was studied through experiments and numerical methods. Tests were conducted using a hooked collar of a width of 1.25b and a height of 0.25b, where b is the bridge-pier width. The hooked-collar efficiency was evaluated by testing different hooked-collar placements within the bridge-pier, which were compared to the bridge-pier without any collar. A double hooked-collar configuration, one placed at the bed level and the other buried 0.25b, was the most efficient at reducing the scour hole. In other cases, a hooked-collar positioned 0.25b above the bed slightly reduced the scour hole and had similar scour patterns when compared to the pier without the hooked-collar. The flow fields along the vertical symmetrical plane in the experiments are also presented. Laboratory experiments and numerical tests show that maximal downflow is highly reduced along with a corresponding decrease in horseshoe vortex strength for the experiments with the hooked-collar, compared to cases without the hooked-collar. The flow fields reveal that the maximum turbulent kinetic energy decreases with the installation of the hooked-collar.

Methods for Detection of Anticarsia gemmatalis Nucleopolyhedrovirus DNA in Soil

1999 ◽  
Vol 65 (6) ◽  
pp. 2307-2311 ◽  
Author(s):  
R. R. de Moraes ◽  
J. E. Maruniak ◽  
J. E. Funderburk
Keyword(s):  
Laboratory Experiments ◽  
Dna Isolation ◽  
Pcr Amplification ◽  
Soil Samples ◽  
Anticarsia Gemmatalis ◽  
Isolation Method ◽  
Viral Dna ◽  
Pcr Inhibitors ◽  
Magnetic Capture ◽  
Pcr Products

ABSTRACT Two methods, phenol-ether and magnetic capture-hybridization (MCH), were developed and compared with regard to their sensitivities and abilities to extract the DNA of the insect baculovirus Anticarsia gemmatalis nucleopolyhedrovirus (AgMNPV) from soil and to produce DNA amplifiable by PCR. Laboratory experiments were performed with 0.25 g of autoclaved soil inoculated with different viral concentrations to optimize both methods of baculovirus DNA extraction and to determine their sensitivities. Both procedures produced amplifiable DNA; however, the MCH method was 100-fold more sensitive than the phenol-ether procedure. The removal of PCR inhibitors from the soil appeared to be complete when MCH was used as the viral DNA isolation method, because undiluted aliquots of the DNA preparations could be amplified by PCR. The phenol-ether procedure probably did not completely remove PCR inhibitors from the soil, since PCR products were observed only when the AgMNPV DNA preparations were diluted 10- or 100-fold. AgMNPV DNA was detected in field-collected soil samples from 15 to 180 days after virus application when the MCH procedure to isolate DNA was coupled with PCR amplification of the polyhedrin region.

Selective isolation and distribution of the genus Planomonospora in soils

2001 ◽  
Vol 47 (3) ◽  
pp. 253-263 ◽  
Author(s):  
Shin-ichi Suzuki ◽  
Toru Okuda ◽  
Saburo Komatsubara
Keyword(s):  
New Caledonia ◽  
Skim Milk ◽  
First Record ◽  
Soil Samples ◽  
Gellan Gum ◽  
Alkaline Soils ◽  
Selective Isolation ◽  
Medium Ph ◽  
Ethanesulfonic Acid ◽  
High Yields

For the screening of bioactive compounds and study of global distribution, a selective isolation method for Planomonospora strains by centrifugation from soil is examined. Planomonospora strains produced characteristic sporangia on the humic acid-trace salts gellan gum medium (pH 9.0) so that this genus was readily recognized on the isolation plate. High yields of motile spores were obtained by using a flooding solution containing 0.1% skim milk in 5 mM N-cyclohexyl-2-amino-ethanesulfonic acid (pH 9.0) followed by incubating the preparation at 32°C for 90 min, centrifuging it at 1000 × g for 10 min, and further incubation at 32°C for 60 min after centrifugation. By combining the techniques described above, we isolated 246 Planomonospora strains from 137 of the 1200 soil samples examined. Ninety-four percent of these strains were recovered from neutral to slightly alkaline soils (pH 7.0 to 9.0). Strains of P. venezuelensis group were obtained from 13 soil samples (1.1%), which were collected in Bolivia, Cyprus, Egypt, Greece, India, Japan, New Caledonia, and Turkey. Strains of this group appear widely distributed in the soil of tropical to temperate regions. To our knowledge, this is the first record that strains of this group have been isolated from a location other than Venezuela.Key words: Planomonospora, gellan gum, selective isolation, distribution, actinomycete.

scholarly journals California Bearing Ratio of Palm Oil Contaminated Subgrade under Soaked Condition

2020 ◽  
Vol 2 (1) ◽  
Author(s):  
S.M Adeyinka
Keyword(s):  
Particle Size ◽  
Palm Oil ◽  
Oil Palm ◽  
Laboratory Experiments ◽  
Research Work ◽  
Dry Weight ◽  
Soil Samples ◽  
California Bearing Ratio ◽  
Engineering Work ◽  
Negative Effect

The effects of palm oil contaminant on the soaked California Bearing Ratio (CBR) of subgrade was investigated. The following objectives were set out in accordance with BS 1377: 1-8 (1990) and BS 1924 (1990); Particle Size Distribution, Atterberg Limits, Compaction and California Bearing Ratio for oil-palm contaminated and uncontaminated subgrade. Palm oil and four soil samples are used in this research work. The air-dried samples were contaminated with oil-palm at 0, 2,4, 6, 8 & 10% of the dry weight of the samples for 7 days thereafter air-dried for another 7 days. Laboratory experiments on the control (0%) and palm oil-contaminated subgrade samples were conducted after 24 hours of soaking the samples in accordance with BS 1924 (1990). It was found that the soaked CBR for the contaminated soil showed a lower values (17.45%, 24.80%, 49.50% and 21.50%) than the control CBR values (48.20%, 138.40%, 160.00 and 132.10%) for sample A, B, C and D respectively. It is therefore concluded that palm oil has a negative effect on the geotechnical properties and the mechanical strength of the soil hence it is not suitable in any Civil Engineering work.

Protective effect of clay minerals on adsorbed nucleic acid against UV radiation: possible role in the origin of life

2004 ◽  
Vol 3 (1) ◽  
pp. 17-19 ◽  
Author(s):  
F. Scappini ◽  
F. Casadei ◽  
R. Zamboni ◽  
M. Franchi ◽  
E. Gallori ◽  
...  
Keyword(s):  
Nucleic Acid ◽  
Protective Effect ◽  
Origin Of Life ◽  
Clay Minerals ◽  
Uv Radiation ◽  
Laboratory Experiments ◽  
Biological Evolution ◽  
The Earth ◽  
The Origin Of Life ◽  
Uv Photons

The effect of UV radiation on solutions of free and clay-adsorbed DNA has been investigated. It turns out that clay (montmorillonite/kaolinite) adsorbed nucleic acid undergoes less radiation damage than free nucleic acid. Our laboratory experiments have an astronomical counterpart in terms of solar irradiance on the Earth. An origin of life scenario is proposed where ubiquitous clay minerals lead the surface chemistry of the molecules relevant to the biological evolution and at the same time protect them from the deadly rainfall of UV photons.

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