Processes and Factors Affecting Phosphorus Sorption in Soils

2020 ◽  
Author(s):  
Samuel Kwesi Asomaning
Keyword(s):  
Phosphorus Sorption ◽  
Factors Affecting

Factors affecting the retention of phosphorus applied as superphosphate to the sandy soils in south-eastern South Australia

Soil Research ◽  
1981 ◽  
Vol 19 (2) ◽  
pp. 167 ◽  
Author(s):  
DC Lewis ◽  
AL Clarke ◽  
WB Hall
Keyword(s):  
Organic Carbon ◽  
South Australia ◽  
Sandy Soils ◽  
Soil Parameters ◽  
Phosphorus Retention ◽  
Phosphorus Sorption ◽  
Leaching Losses ◽  
Factors Affecting ◽  
South Eastern ◽  
Active Iron

The retention of phosphorus applied as superphosphate was measured in 31 multi-rate experiments on siliceous sands in the south-east of South Australia. The amount of phosphorus retained in the top 30 cm of soil and recovered in harvested pasture 5 months after application ranged from 0 to 100% and averaged 57% for an average dressing of 32 kg phosphorus ha-1. Of the eight soil parameters measured, 'active' iron, 'active' aluminium, organic carbon and phosphorus sorption were most closely correlated with phosphorus retention. Combinations of these variables accounted for far more of the variation than did single factors. 'Active' iron and organic carbon accounted for 53.6% of the variation. The inclusion of quadratic 'active' iron and aluminium terms improved the fit with 63.9% of the variation accounted for. Rainfall during the experiments varied from 168 to 484 mm but had no effect on retention. Some agronomic implications of the leaching losses are discussed. It is considered that a measure of 'active' iron and organic carbon could be used as indicators of leaching and could assist in determining phosphorus recommendations in the region.

Phosphorus interactions with Martian soil simulants

2021 ◽  
Author(s):  
Sofia Manimanaki ◽  
Dimitris Mitrogiannis ◽  
Ioannis Baziotis ◽  
Maria Psychoyou ◽  
Ioannis Papanikolaou ◽  
...  
Keyword(s):  
Aqueous Solutions ◽  
Raw Material ◽  
Phosphorus Sorption ◽  
Reference Case ◽  
Factors Affecting ◽  
Central Florida ◽  
Martian Soil ◽  
Initial Ph ◽  
Essential Nutrient ◽  
Isothermal Kinetic

<p>Phosphorus (P) is an essential nutrient for plant growth. According to the vision of circular bioeconomy, the management of nutrient-rich wastewaters should include both treatment and utilization goals (Battista & Bolzonella, 2019). Consequently, the application of in-situ resources utilization (ISRU), using typical Martian soil (e.g., Yen et al., 2005), is vital for the sustainability of future long-term settlements on Mars.</p><p>Martian soil simulants, provided by The CLASS Exolith Lab from the University of Central Florida, were tested for their phosphorus sorption capacity. Sorption of phosphate anions (PO<sub>4</sub>-P) from aqueous solutions (AS) of KH<sub>2</sub>PO<sub>4</sub> and sodium bicarbonate, as well as from hydrolyzed human urine (HU) was examined at a preliminary stage, using three Martian soil simulants (MGS-1; Rocknest soil, MGS-1S; M-WIP Reference Case B and MGS-1C; M-WIP Reference Case C; Cannon et al. 2019). In particular, isothermal, kinetic, pH, temperature, initial sorbent concentration (5 g soil simulant/L AS or HU, 10 g/L and 15 g/L) and desorption experiments were carried out, the duration of which ranged from five days to three weeks.</p><p>The percentage of phosphorus removal was up to 60 % for the aqueous solutions and 24 % for the hydrolyzed human waste. The sulfate-rich simulant (MGS-1S) exhibited the best results. The major phases of MGS-1S are: gypsum, plagioclase, basaltic glass, pyroxene, and olivine. Temperature and the initial pH seem to be the dominant factors affecting P sorption. Equilibrium between sorbent and AS was achieved between five and seven days, as indicated by kinetic experiments. Isothermal experiments at 25 ⁰C with AS of different P concentrations displayed a linear correlation between adsorption capacity (q) and P-concentration (r<sup>2</sup>=0.98). Maximum q was observed at 8.5 and 27 mg/g for AS and HU experiments respectively, when 5 g/L of initial sorbent concentration was used. X-ray diffraction (XRD) of the sorbents treated with AS showed the presence of the newly formed phases berlinite and brushite. Perhaps due to hydrolysis of the pre-existing illite, aluminum bound with the solution’s phosphates, forming berlinite and buffering AS’s pH to lower values. Formation of brushite is possibly indicative of gypsum (predominant phase in the raw material) dissolution subsequently releasing sulfate anions. In a similar approach, XRD evaluation of the sorbents treated with HU revealed the newly formed phases calcite and hannayite. Phosphate and ammonia ions were likely to bind to the sample and were precipitated within newly formed calcium-bearing phases.</p><p>These experiments form a preliminary study of Martian soil simulants, and initial results indicate a possible use of Martian soils as waste recipients or as fertilizers in future missions.</p><p><strong>References</strong></p><p>Battista, F., & Bolzonella, D. (2019). Waste and Biomass Valorization, 10(12), 3701-3709.<br>Cannon, K. M., Britt, D. T., Smith, T. M., Fritsche, R. F., & Batcheldor, D. (2019). Icarus, 317, 470-478.<br>Yen, A. S., Gellert, R., Schröder, C., Morris, R. V., Bell, J. F., Knudson, A. T., ... & Blaney, D. (2005). Nature, 436(7047), 49-54.</p>

Factors affecting phosphorus sorption in palexerults of western Spain

1992 ◽  
Vol 23 (3-4) ◽  
pp. 389-398 ◽  
Author(s):  
R. Espejo ◽  
F.R. Cox
Keyword(s):  
Phosphorus Sorption ◽  
Factors Affecting ◽  
Western Spain

Progress In The Practical Application Of Automated Image Analysis To Tem Negatives

1977 ◽  
Vol 35 ◽  
pp. 214-217
Author(s):  
F. A. Heckman ◽  
E. Redman ◽  
J.E. Connolly
Keyword(s):  
Image Analysis ◽  
Image Quality ◽  
Exposure Time ◽  
Image Contrast ◽  
Automated Image Analysis ◽  
Practical Application ◽  
Factors Affecting ◽  
High Image Quality ◽  
Qualitative Evidence ◽  
Comprehensive Study

In our initial publication on this subject1) we reported results demonstrating that contrast is the most important factor in producing the high image quality required for reliable image analysis. We also listed the factors which enhance contrast in order of the experimentally determined magnitude of their effect. The two most powerful factors affecting image contrast attainable with sheet film are beam intensity and KV. At that time we had only qualitative evidence for the ranking of enhancing factors. Later we carried out the densitometric measurements which led to the results outlined below.Meaningful evaluations of the cause-effect relationships among the considerable number of variables in preparing EM negatives depend on doing things in a systematic way, varying only one parameter at a time. Unless otherwise noted, we adhered to the following procedure evolved during our comprehensive study:Philips EM-300; 30μ objective aperature; magnification 7000- 12000X, exposure time 1 second, anti-contamination device operating.

Factors affecting microstructural scale in liquid crystalline polymers

1990 ◽  
Vol 48 (4) ◽  
pp. 220-221
Author(s):  
Christine M. Dannels ◽  
Christopher Viney
Keyword(s):  
Liquid Crystalline ◽  
Liquid Crystalline Polymers ◽  
Factors Affecting ◽  
Crystalline Polymers ◽  
Thermal Expansion Coefficients ◽  
Low Thermal Expansion ◽  
Lower Viscosity ◽  
Fine Microstructure ◽  
Planar Orientation ◽  
Strength And Stiffness

Processing polymers from the liquid crystalline state offers several advantages compared to processing from conventional fluids. These include: better axial strength and stiffness in fibers, better planar orientation in films, lower viscosity during processing, low solidification shrinkage of injection moldings (thermotropic processing), and low thermal expansion coefficients. However, the compressive strength of the solid is disappointing. Previous efforts to improve this property have focussed on synthesizing stiffer molecules. The effect of microstructural scale has been overlooked, even though its relevance to the mechanical and physical properties of more traditional materials is well established. By analogy with the behavior of metals and ceramics, one would expect a fine microstructure (i..e. a high density of orientational defects) to be desirable.Also, because much microstructural detail in liquid crystalline polymers occurs on a scale close to the wavelength of light, light is scattered on passing through these materials.

Factors affecting dentist participation in a state Medicaid program

1990 ◽  
Vol 54 (11) ◽  
pp. 638-643 ◽  
Author(s):  
PC Damiano ◽  
ER Brown ◽  
JD Johnson ◽  
JP Scheetz
Keyword(s):  
Medicaid Program ◽  
Factors Affecting

Factors affecting dental utilization of elders aged 75 years or older

1986 ◽  
Vol 50 (11) ◽  
pp. 673-677 ◽  
Author(s):  
AA Wilson ◽  
LG Branch
Keyword(s):  
Factors Affecting ◽  
Dental Utilization

Speech Therapy Services in a Large School System: A Six-Year Overview

1976 ◽  
Vol 7 (4) ◽  
pp. 207-219 ◽  
Author(s):  
Constance P. DesRoches
Keyword(s):  
School System ◽  
Speech Therapy ◽  
Factors Affecting ◽  
Case Load ◽  
Number Of Children ◽  
School Population ◽  
System A ◽  
Therapy Services ◽  
And Shifts ◽  
Selection Factors

A statistical review provides analysis of four years of speech therapy services of a suburban school system which can be used for comparison with other school system programs. Included are data on the percentages of the school population enrolled in therapy, the categories of disabilities and the number of children in each category, the sex and grade-level distribution of those in therapy, and shifts in case-load selection. Factors affecting changes in case-load profiles are identified and discussed.

Assessing the Link Between Perception and Production in Cantonese Tone Acquisition

2019 ◽  
Vol 62 (5) ◽  
pp. 1243-1257 ◽  
Author(s):  
Peggy Pik Ki Mok ◽  
Holly Sze Ho Fung ◽  
Vivian Guo Li
Keyword(s):  
Language Acquisition ◽  
General Principle ◽  
Choice Task ◽  
Factors Affecting ◽  
Tone Pair ◽  
Tone Production ◽  
Monosyllabic Words ◽  
Early Production ◽  
Forced Choice Task ◽  
Production Accuracy

Purpose Previous studies showed early production precedes late perception in Cantonese tone acquisition, contrary to the general principle that perception precedes production in child language. How tone production and perception are linked in 1st language acquisition remains largely unknown. Our study revisited the acquisition of tone in Cantonese-speaking children, exploring the possible link between production and perception in 1st language acquisition. Method One hundred eleven Cantonese-speaking children aged between 2;0 and 6;0 (years;months) and 10 adolescent reference speakers participated in tone production and perception experiments. Production materials with 30 monosyllabic words were transcribed in filtered and unfiltered conditions by 2 native judges. Perception accuracy was based on a 2-alternative forced-choice task with pictures covering all possible tone pair contrasts. Results Children's accuracy of production and perception of all the 6 Cantonese tones was still not adultlike by age 6;0. Both production and perception accuracies matured with age. A weak positive link was found between the 2 accuracies. Mother's native language contributed to children's production accuracy. Conclusions Our findings show that production and perception abilities are associated in tone acquisition. Further study is needed to explore factors affecting production accuracy in children. Supplemental Material https://doi.org/10.23641/asha.7960826

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