File Name: adsorption of phosphate by aluminum and iron in soils .zip
Phosphorus P is essential to all forms of life on this planet. It is an essential nutrient necessary for growth and development of plants and animals on which our food supply depends. Phosphorus constitutes about 0. It can reduce plant growth and development and potentially limit crop yield. Improved phosphorus management can create profitable crop production systems while reducing negative impacts on the environment.
We evaluated the effect of 1 N NH 4 OAc and sodium-citrate dithionite extractable forms of soil Fe, Al, and Mn on P-sorption of a flooded acid sulfate soil Sulfic Tropaquepts and a non-acid sulfate soil Typic Tropaquepts under different soil oxidation-reduction and pH conditions. After the incubation period, the soil suspensions in the first treatment control were not washed or pretreated with any extractants. Sorption isotherms were described by the classical Langmuir equation. Significant correlations between the P-sorption parameters and the amount of free iron oxides indicated the primary role of iron oxides in P-sorption of acid sulfate soils. Aluminium oxides seemed to play a secondary role in P-sorption of these soils. Manganese also showed an important effect on P-sorption, but the mechanism is ambiguous.
Continuous crop expansion has led to a growing demand for phosphate fertilizers. A sound knowledge of the dynamics of phosphorus, and its interaction with iron oxides and organic matter, can be useful to develop effective strategies for sustainable management, especially in a scenario of increasing shortage of mineral phosphate resources. In this paper, we review the relationship of phosphate to iron oxides and organic matter, and its effect on phosphorus availability. Crops typically obtain phosphate from weathered minerals and dissolved fertilizers. However, the amount of phosphorus present in the soil solution depends on the extent to which it is adsorbed or desorbed by iron oxides, which may be influenced by interactions with organic matter. Therefore, systems for fertilizer recomendation based on methodologies considering interactions between soil components such as oxides and organic matter, and the phosphorus sorption capacity resulting from such interactions e. The world population is expected to rise from 7.
Soil phosphorus P adsorption and desorption occur in an important endogenous cycle linked with soil fertility problems and relevant to the environmental risk assessment of P. In our study, the effect of long-term inorganic and organic fertilization on P adsorption and desorption characteristics in relation to changes in soil properties was evaluated by selecting three long-term experimental sites in southern China. The adsorption and desorption characteristics of P were evaluated using Langmuir and Freundlich isotherms. All three treatments fit these equations well.
Assessment of phosphorus status influenced by Al and Fe compounds in volcanic grassland soils. Cartes 1,2 , R.
The subject of this chapter is soil chemistry. The chapter aims to give an overview of the major mechanisms responsible for phosphate sorption i. According to studies conducted by some soil scientists, the major soil factors affecting P sorption are time, soil pH, soil organic matter, and iron and aluminium oxides of soils. Studies conducted indicated that adsorption of the P increases as the P ages in the soil.
Principal mechanisms for phosphorus P removal in bioretention are the filtration of particulate-bound P and chemical sorption of dissolved P see Hunt et al. Most stormwater control measures SCMs capture particulate P by settling or filtration, but leave dissolved P typically phosphates untreated. This untreated P accounts on average for 45 percent of total phosphorus in stormwater runoff and can be up to 95 percent of the total phosphorus, depending on the storm event Erickson et al. Dissolved phosphorus is bioavailable and represents a significant concern for surface water quality. Phosphorus sorbing materials contain a metal cation typically di or trivalent that reacts with dissolved phosphorus to create an insoluble compound by adsorption or precipitation or both Buda et al.
In contrast to nitrogen, the atmosphere does not provide phosphorus. However, the phosphorus cycle is by no means less complex than the nitrogen cycle, and there are many factors that affect the availability of phosphorus in the soil. The diagram below is an illustration of the phosphorus cycle. Figure A representation of the phosphorus cycle.
SUMMARY The phosphate adsorption capacity (Pmax) of samples from various In the soils investigated aluminium and iron oxides were the main phosphate.
In contrast to its behaviour on soil clays and in aqueous solution, aluminium is more extensively hydrolysed between pH3 and 4. The amount of phosphate adsorbed depended not only on the amount of Al adsorbed but also on the basicity of the adsorbed Al. Once adsorbed, the Al was quite stable and P adsorption on the Al-exchanger was unaffected by a rise in pH from 4. This is a preview of subscription content, access via your institution. Rent this article via DeepDyve.
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Стоя над Хейлом и стараясь унять дрожь, Сьюзан услышала приближающиеся шаги и медленно обернулась. В проломе стены возникла фигура Стратмора. Он был бледен и еле дышал. Увидев тело Хейла, Стратмор вздрогнул от ужаса.
Стратмору едва не удалось сделать предлагаемый стандарт шифрования величайшим достижением АНБ: если бы он был принят, у агентства появился бы ключ для взлома любого шифра в Америке.
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Было подсчитано, что для успешной атаки на стандартный ключ самому быстрому компьютеру АНБ - секретнейшему Крей-Джозефсону II - потребуется более девятнадцати лет.
- Это грязный трюк. - Трюк? - Теперь уже Стратмор не мог скрыть свое раздражение. - Это вовсе не трюк. Да я вообще слова ему не сказал о деньгах. Я попросил оказать мне личную услугу.
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Abstract A slightly acid soil was treated with dilute phosphate solutions of pH 7 to study the mechanism of phosphate fixation. Two reactions operating at different.Amable M. 18.05.2021 at 04:31
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