scholarly journals Seasonal and spatial variations in soil nitrogen and phosphorus supply rates in a boreal aspen forest

1997 ◽  
Vol 77 (4) ◽  
pp. 597-612 ◽  
Author(s):  
Wei Z. Huang ◽  
Jeff J. Schoenau
Keyword(s):  
Ion Exchange ◽  
Nutrient Uptake ◽  
Forest Floor ◽  
Forest Ecosystems ◽  
Nutrient Supply ◽  
Plant Nutrient ◽  
Supply Rate ◽  
Aspen Forest ◽  
Exchange Resins ◽  
P Supply

Soil nitrogen (N) and phosphorus (P) supply is one of the growth limiting factors in many forest ecosystems. Seasonal patterns in soil N and P supply rate were examined during a 2-yr period (1994–1995) for forest floor (L, F and H) and upper mineral (Ae) horizons in an 80-yr-old aspen forest in Saskatchewan, Canada. Accumulation of plant nutrient ions on ion exchange resins incubated in the field can provide an estimate of nutrient supply rate in soils because ion exchange resins have the potential ability to simulate nutrient flux to plant roots. Nutrient supply rates and the effect of plant uptake on nutrient supply rate was assessed using ion exchange membranes buried inside and outside polyvinyl chloride (PVC) cylinders. The difference between ion flux to the membranes inside (root uptake excluded) versus outside the cylinders was used as an index of plant nutrient uptake. From May to October, nutrient uptake (µg 10 cm−2 2 wk−2) by plants ranged from 1.6 to 31.7 (NO3−-N), from 2.7 to 13.7 (NH4+-N) and from 2.6 to 12.7 (P), with maximum N and P uptake in summer. Nutrient uptake by plants also varied among horizons. In general, plant uptake of NO3−-N, NH4+-N and P was highest in the H horizon, followed by the F and Ae horizons, with lowest uptake apparent in the L horizon. The results are consistent with the distribution of plant fine roots: most were found in the H horizon (68%), followed by the Ae and F horizons (15%), and the L (2%) horizon. Autumn litterfall represented a nutrient return of 28–40 kg N ha–1 and 4–7 kg P ha–1 to the forest floor which coincided with an increase in ion supply rates in the forest floor. During the growing season, atmospheric inputs via bulk deposition and throughfall contributed small amounts of N (1.8 kg NH4+-N ha–1 and 0.23 kg NO3–-N ha–1) and P (1.38 kg ha−1 inorganic P) to the forest floor. Recycling of nutrients by litterfall and subsequent mineralization and re-assimilation by plant roots in the forest floor is a dynamic and important component of nutrient cycling in boreal aspen forest ecosystems. Key words: Forest floor, ion exchange membranes, nutrient supply

Availability of nitrogen and phosphorus in the forest floors of Rocky Mountain coniferous forests

1992 ◽  
Vol 22 (4) ◽  
pp. 593-600 ◽  
Author(s):  
Cindy E. Prescott ◽  
John P. Corbin ◽  
Dennis Parkinson
Keyword(s):  
Forest Floor ◽  
Lodgepole Pine ◽  
Ammonium Phosphate ◽  
Nutrient Supply ◽  
Nutrient Concentrations ◽  
Supply Rate ◽  
Nitrogen And Phosphorus ◽  
Forest Floors ◽  
P Supply ◽  
Floor Material

Nutrient supply rate and limitation were measured in forest floors of lodgepole pine, white spruce–lodgepole pine, and Engelmann spruce–subalpine fir (pine, spruce, and fir forests, respectively) forests in the Kananaskis Valley of southwestern Alberta. Earlier analyses of the nutrient content of foliage and litter indicated low N and P supply in the pine forest, high P supply in the spruce forest, and high N–low P supply in the fir forest. Measurements of nutrient supply (insitu rates of net mineralization, extractable P, and uptake of N and P from the forest floor in pot trials) confirmed the differences in N and P supply among the forests and indicated that nutrient concentrations in needle litter were useful as an index of nutrient supply rate. Subtractive tests were useful in identifying the most limiting nutrients in each forest: lodgepole pine seedlings grown in forest floor material from the pine and spruce stands responded with increased growth to the addition of N; those in fir forest floor material responded to P addition. Vector analysis of N and P concentrations and contents in needles from trees fertilized with ammonium phosphate sulphate showed responses to both N and P in the pine site, no response at the spruce site, and response to P at the fir site.

Placement of ion-exchange membranes for monitoring nutrient release from flooded soils

2018 ◽  
Vol 98 (4) ◽  
pp. 709-715 ◽  
Author(s):  
E. Bremer ◽  
J.J. Miller ◽  
T. Curtis
Keyword(s):  
Ion Exchange ◽  
Plant Root ◽  
Soil Surface ◽  
Nutrient Supply ◽  
Nutrient Loss ◽  
Ion Exchange Membranes ◽  
Supply Rate ◽  
Overlying Water ◽  
The Impact ◽  
Prs Probes

Placement of Plant Root Simulator (PRS®) probes (ion-exchange membranes in a plastic support) may strongly influence nutrient supply measurements and their relationship to nutrient loss to overlying water due to gradients in ion activity and redox potential with depth. A laboratory study was conducted with two soils contrasting in potential nutrient loss (manured vs. unamended control) to determine the impact of probe placement (vertical, horizontal, and flat on the soil surface) on nutrient supply rate. The supply rates of the redox-sensitive nutrients Mn and Fe were generally 1–2 orders of magnitude lower for PRS probes placed on the soil surface than buried vertically. In contrast, the supply rate of P and K varied by 1–2 orders of magnitude between soils, but placement impacts were modest or absent. The ratio between manured and control soils in water P concentration was identical to that of soil P supply rate determined with PRS probes placed flat on the soil surface. All placements were effective in demonstrating the increased potential for loss of P and K from the manured soil, but only measurements from PRS probes placed on the soil surface were closely related to loss of the redox-sensitive nutrients Mn and Fe.

Embedding Procedure for Water Swollen Samples

1970 ◽  
Vol 28 ◽  
pp. 504-505
Author(s):  
Ann M. Thomas ◽  
Virginia Shemeley
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Ion Exchange ◽  
Structural Changes ◽  
Cross Linking ◽  
Ion Exchange Resins ◽  
Transmission Electron ◽  
First Pass ◽  
Exchange Resins

Those samples which swell rapidly when exposed to water are, at best, difficult to section for transmission electron microscopy. Some materials literally burst out of the embedding block with the first pass by the knife, and even the most rapid cutting cycle produces sections of limited value. Many ion exchange resins swell in water; some undergo irreversible structural changes when dried. We developed our embedding procedure to handle this type of sample, but it should be applicable to many materials that present similar sectioning difficulties.The purpose of our embedding procedure is to build up a cross-linking network throughout the sample, while it is in a water swollen state. Our procedure was suggested to us by the work of Rosenberg, where he mentioned the formation of a tridimensional structure by the polymerization of the GMA biproduct, triglycol dimethacrylate.

Applications of Ion Exchange Resin in Oral Drug Delivery Systems

2017 ◽  
Vol 7 (03) ◽  
Author(s):  
Kathpalia Harsha ◽  
Das Sukanya
Keyword(s):  
Drug Delivery ◽  
Ion Exchange ◽  
Drug Delivery Systems ◽  
Oral Drug Delivery ◽  
Physical Stability ◽  
Delivery Systems ◽  
Oral Drug ◽  
Ion Exchange Resins ◽  
Exchange Resins ◽  
Oral Drug Delivery Systems

Ion Exchange Resins (IER) are insoluble polymers having styrene divinylbenzene copolymer backbone that contain acidic or basic functional groups and have the ability to exchange counter ions with the surrounding aqueous solutions. From the past many years they have been widely used for purification and softening of water and in chromatographic columns, however recently their use in pharmaceutical industry has gained considerable importance. Due to the physical stability and inert nature of the resins, they can be used as a versatile vehicle to design several modified release dosage forms The ionizable drug is complexed with the resin owing to the property of ion exchange. This resin complex dissociatesin vivo to release the drug. Based on the dissociation strength of the drug from the drug resin complex, various release patterns can be achieved. Many formulation glitches can be circumvented using ion exchange resins such as bitter taste and deliquescence. These resins also aid in enhancing disintegrationand stability of formulation. This review focuses on different types of ion exchange resins, their preparation methods, chemistry, properties, incompatibilities and their application in various oral drug delivery systems as well as highlighting their use as therapeutic agents.

THE DISPOSAL OF USED ION EXCHANGE RESINS

2004 ◽  
Vol 3 (3) ◽  
pp. 447-455
Author(s):  
Viky Dicu ◽  
Carmen Iesan ◽  
Mihai Chirica ◽  
Satish Bapat
Keyword(s):  
Ion Exchange ◽  
Ion Exchange Resins ◽  
Exchange Resins

FTIR ANALYSIS OF ION EXCHANGE RESINS WITH APPLICATION IN PERMANENT HARD WATER SOFTENING

2014 ◽  
Vol 13 (9) ◽  
pp. 2145-2152 ◽  
Author(s):  
Liliana Lazar ◽  
Laura Bulgariu ◽  
Bogdan Bandrabur ◽  
Ramona-Elena Tataru-Farmus ◽  
Mioara Drobota ◽  
...  
Keyword(s):  
Ion Exchange ◽  
Hard Water ◽  
Ion Exchange Resins ◽  
Ftir Analysis ◽  
Water Softening ◽  
Exchange Resins
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