1M KCl Research Articles

Immunological Quantitation and Localization of ACAT-1 and ACAT-2 in Human Liver and Small Intestine

By using specific anti-ACAT-1 antibodies in immunodepletion studies, we previously found that ACAT-1, a 50-kDa protein, plays a major catalytic role in the adult human liver, adrenal glands, macrophages, and kidneys but not in the intestine. Acyl-coenzyme A:cholesterol acyltransferase (ACAT) activity in the intestine may be largely derived from a different ACAT protein. To test this hypothesis, we produced specific polyclonal anti-ACAT-2 antibodies that quantitatively immunodepleted human ACAT-2, a 46-kDa protein expressed in Chinese hamster ovary cells. In hepatocyte-like HepG2 cells, ACAT-1 comprises 85-90% of the total ACAT activity, with the remainder attributed to ACAT-2. In adult intestines, most of the ACAT activity can be immunodepleted by anti-ACAT-2. ACAT-1 and ACAT-2 do not form hetero-oligomeric complexes. In differentiating intestinal enterocyte-like Caco-2 cells, ACAT-2 protein content increases by 5-10-fold in 6 days, whereas ACAT-1 protein content remains relatively constant. In the small intestine, ACAT-2 is concentrated at the apices of the villi, whereas ACAT-1 is uniformly distributed along the villus-crypt axis. In the human liver, ACAT-1 is present in both fetal and adult hepatocytes. In contrast, ACAT-2 is evident in fetal but not adult hepatocytes. Our results collectively suggest that in humans, ACAT-2 performs significant catalytic roles in the fetal liver and in intestinal enterocytes.

Mechanisms of DNA protection in Halobacterium salinarium, an extremely halophilic bacterium

Halobacterium salinarium exhibits resistance to ultraviolet (UV) and ionizing radiation. This organism contains carotenoids and also accumulates highly concentrated KCl in the cell. In the present study, DNA lesions generated by UV and ionizing radiation were measured in vitro in the presence and absence of bacterioruberin, the major carotenoid of H. salinarium, and KCl to elucidate their influences on DNA damage production. When plasmid DNA (pDEL19) was UV-irradiated, formation of cyclobutane pyrimidine dimers (CPD) was slightly suppressed by 0.1 mM bacterioruberin. The same concentration of bacterioruberin suppressed the formation of DNA single strand breaks (SSB) by ionizing radiation more efficiently. The formation of CPD by UV and SSB by ionizing radiation was also repressed by 2M KCl but protection against ionizing radiation was extremely efficient.

Self-Aggregation of DNA Oligomers with XGG Trinucleotide Repeats: Kinetic and Atomic Force Microscopy Measurements

Turbidity measurements via absorbance monitoring at 320nm were employed to obtain autocatalytic-like kinetic profiles of K+-induced aggregate formation of d(XGG)4 and some related oligomers, where X=A, C, G, and T. At least 1M KCl is needed to observe the turbidity-measurable aggregation at pH 8, and the relative propensity for aggregate formation is shown to follow the order d(GGG)4>d(AGG)4 ≈ d(TGG)4 ≫ d(CGG)4. The presence of Mg2+ greatly facilitates and dramatically reduces the amount of K+ required to initiate aggregation and significantly enhances the thermal stabilities of the aggregates. Replacement of K+ by Na+ fails to induce a similar phenomenon. The Ψ-type CD characteristics of aggregates are strongly dependent on the sequence and ionic conditions. Despite their ease of aggregate formation, oligomers with AGG trinucleotide repeats fail to exhibit Ψ-CD formation. The propensity for aggregation is greatly affected by the chain length, with oligomers of four repeats being most facile. Appending X base at the 3′ end of d(GGXGGXGGXGG) appears to provide a greater hindrance to aggregation than at the 5′ end. Atomic force microscopic images support some of these findings and reveal the morphologies of these aggregates. The presence of MgCl2 in solutions appears to considerably elongate the K+-induced aggregates.

Sorption of neptunium on iron-containing minerals

The sorption of neptunium on magnetite, hematite and biotite in 0.05, 0.1 and 0.2 M NaNO3 was investigated at 25°C for pH values between 1 and 8. The pH dependence of the sorption was different for the three minerals. However, there were no or a little (biotite) dependence of the sorption on ionic strength. After the sorption experiment, desorption with water of which pH was adjusted to corresponding value, 1M KCl and 0.1M K2C2O4 was also carried out to investigate the Np sorption form. It was found that for magnetite 50% of sorbed Np were sorbed by ion exchange and 25% were sorbed on the crystalline part, and that for biotite 35% of Np were sorbed by ion exchange and 30% were sorbed on the crystalline part. The sorption on crystalline part was a dominant mechanism together with ion exchange in magnetite and biotite systems. For hematite system, the sorption mechanism changed from ion exchange to the sorption on noncrystalline and crystalline parts, especially on the crystalline part, around pH6. This phenomenon is considered because surface of hematite changed with increase of pH.

Acidification of a cultivated Alfisol in Venezuela

A moderately acid sandy clay Alfisol was used to grow corn as a monoculture for twenty years using urea fertilization. Successive samplings were performed during crop growth over the last two years (1993 and 1994) in the upper two soil layers (0–20 cm and 20–40 cm) of the control plot where the addition of urea had been interrupted and in a plot still receiving urea (N=132 kg ha‐1). Although aluminum (Al) in 1M KCl reached 2 cmolc kg‐1 and 70% of the effective CEC, Al speciation revealed that the aluminum in the soil solution was well below the toxicity threshold. The results of measurements of pH, buffering capacity, and water‐soluble NO3 ‐ and K+ or exchangeable cations (NH4 +, Ca++, Mg++, Al+++) suggested an increase in acid neutralization capacity (ANC) in the control plot and an insignificant decrease in the fertilized plot.

Cyclic-Voltammetric Observation of Carbonizing Process of Resins

Electrochemical characteristics of several carbon materials prepared from furan resin, imide resin and poly vinylchloride, were studied by cyclic voltammetry in 1M KCl solution and in 5mM Fe (CN) 64-/3--1M KCl solution. Blankcurrent (Ib), potential difference between cathodic and anodic peak (ΔEp) and peakcurrent (Ip) for ferro/ferricyanideredox reactions were closely related to kinds of raw materials, the carbonization temperatures and the holding time. Withincreasing the carbonization temperatures of raw materials and the holding time, ΔEp approached 60mV and Ip increasedto the limiting current. The blank currents, Ib, showed the maximum values for the carbon electrodes carbonized at 800°C.These results suggest that voltammetric measurements on the carbon materials carbonized at various temperatures arehelpful for characterizing the early stage of carbonization process.

Characterization of neoformed illite from hydrothermal experiments at 250 degrees C and P (sub v,soln) ; an HRTEM/ATEM study

Other| December 01, 1998 Characterization of neoformed illite from hydrothermal experiments at 250 degrees C and P (sub v,soln) ; an HRTEM/ATEM study Douglas M. Yates; Douglas M. Yates Washington State University, Department of Geology, Pullman, WA, United States Search for other works by this author on: GSW Google Scholar Philip E. Rosenberg Philip E. Rosenberg Search for other works by this author on: GSW Google Scholar Author and Article Information Douglas M. Yates Washington State University, Department of Geology, Pullman, WA, United States Philip E. Rosenberg Publisher: Mineralogical Society of America First Online: 02 Mar 2017 Online ISSN: 1945-3027 Print ISSN: 0003-004X GeoRef, Copyright 2004, American Geological Institute. American Mineralogist (1998) 83 (11-12_Part_1): 1199–1208. https://doi.org/10.2138/am-1998-11-1208 Article history First Online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Douglas M. Yates, Philip E. Rosenberg; Characterization of neoformed illite from hydrothermal experiments at 250 degrees C and P (sub v,soln) ; an HRTEM/ATEM study. American Mineralogist 1998;; 83 (11-12_Part_1): 1199–1208. doi: https://doi.org/10.2138/am-1998-11-1208 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyAmerican Mineralogist Search Advanced Search Abstract Solid products from hydrothermal experiments conducted at 250 degrees C and P (sub v.soln) were characterized by powder X-ray diffraction (XRD) and ATEM/HRTEM. Experiments were conducted with muscovite, kaolinite, and quartz or amorphous silica in 2M KCl solutions for 43 to 176 d. Post-experiment solution compositions lie either within the illite (0.88 K) stability field or on the illite(0.88 K)-kaolinite or illite(0.88 K)-diaspore univariant boundaries in log (a K (super -) /a H (super -) ) vs. log aH 4 SiO 4 activity space. Transmission electron microscopy (TEM) observations of muscovite grain edges reveal the neoformation of illite crystals with a range of compositions (ATEM) from 0.31 to 0.89 K/O 10 (OH) 2 . The range of K-contents appears to narrow toward 0.88 K/O 10 (OH) 2 with increased experiment duration. HRTEM suggests the presence of 2 to 11 layer fundamental particles composed of illitic layers with 10 A periodicity. Fundamental particle thicknesses increase toward an average of 8 layers/particle with increased experiment duration. In the longer duration experiments, fundamental particle thicknesses were normally distributed about thicknesses of 4 and 8 layers, whereas fundamental particles with thicknesses <4 layers were common in a shorter duration experiment. The compositions and structure of the illites are consistent with the multiphase model, which states that the smectite-to-illite transition occurs through the step-wise formation of solubility-controlling phases consisting of fundamental particles with thicknesses of 1, 2, 4. and > or =8 layers. The increase in K-content and fundamental particle thickness with the extent of reaction suggests that the illite crystals underwent a prograde reaction culminating in the formation of end-member illite [0.88 K/O 10 (OH) 2 ]. This reaction, in conjunction with the previously observed, retrograde reaction from muscovite to end-member illite, demonstrates the stability of end-member illite in the system K 2 O-Al 2 O 3 -SiO 2 -H 2 O at 250 degrees C. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Sensory and Motor Neuron-derived Factor Is a Transmembrane Heregulin That Is Expressed on the Plasma Membrane with the Active Domain Exposed to the Extracellular Environment

The beta-heregulin sensory and motor neuron-derived factor (SMDF) has been suggested to be an important regulator of Schwann cell development and proliferation. In the present study, human SMDF was expressed in cultured cell lines. The cells and the recombinant protein were used to examine the membrane association and biological activity of the growth factor. Transfection of cells with SMDF cDNA constructs bearing FLAG epitope tags at either the amino- or carboxyl-terminal ends of the polypeptide resulted in expression of anti-FLAG immunoreactive polypeptides of approximately 44 and 83 kDa. The 83-kDa polypeptide was the major form expressed on the cell surface, as demonstrated by sensitivity to proteolysis in intact cells and surface biotinylation. SMDF was tightly associated with membranes isolated from transfected cells but was solubilized by Triton X-100. Immunofluorescent staining and immunoprecipitation experiments using cells expressing amino- or carboxyl-terminal tagged SMDF revealed that only the carboxyl-terminal end of the protein is exposed on the cell surface. Membranes from SMDF-transfected cells stimulated tyrosine phosphorylation of the beta-heregulin receptor ErbB3 in Schwann cells. Conditioned medium from transfected cells contained a similar activity, suggesting that SMDF is subject to proteolytic release from the plasma membrane. In contrast with other beta-heregulin isoforms, SMDF failed to bind heparin. Stimulation of Schwann cell ErbB3 receptor phosphorylation by SMDF was not affected by inhibition of Schwann cell heparan sulfate proteoglycan synthesis. These results demonstrate that SMDF is a type II transmembrane protein. This orientation places the active epidermal growth factor homology domain, which is located near the carboxyl-terminal end of the polypeptide, on the cell surface, where it can function as a membrane-anchored growth factor.

Nitrogen cycling involving non-exchangeable ammonium in a gray luvisol

There is considerable interest in determining the bio-availability of non-exchangeable NH4+ (NEA) because it constitutes nearly 10% of the total N in the top 1 m of soil. NEA is NH4+ present in the soil that is not extractable with neutral K salt solutions, e.g. 1M KCl. This study was conducted in 1994 and 1995 to quantify the amount of NEA released by a gray luvisolic clay loam soil in Alberta, Canada, during the growing season. Replicated plots under: (1) continuous bromegrass, (2) continuous barley, and (3) barley since 1991 but previously under a continuous forage legume, were sampled four times through the growing season to a depth of 80 cm. The first sampling was done before seeding of barley. Cropping systems and their interaction with time of sampling had no effect on NEA. The NEA-N pool in the soil decreased significantly during grain-filling and maturing of barley, and had returned to approximately its initial level by the following spring. The maximum amount of NEA-N released was 15 g m–2 at barley grain-filling in 1994, and 10 g m–2 3 weeks after barley had matured in 1995. Approximately 24% of the released NEA accumulated as 1M-KCl-extractable NH4+ in 1994, 20–30% was absorbed by the barley crop, and most of the remainder was probably assimilated by soil micro-organisms and immobilized in soil organic matter. The release of significant amounts of NEA during crop growth has implications for N cycling and measurements of mineralization/immobilization turnover rates.

The cell wall porin of Nocardia farcinica: biochemical identification of the channel-forming protein and biophysical characterization of the channel properties.

A channel-forming protein was identified in cell wall extracts of the Gram-positive, strictly aerobic bacterium Nocardia farcinica. The cell wall porin was purified to homogeneity and had an apparent molecular mass of about 87 kDa on tricine-containing SDS-PAGE. When the 87 kDa protein was boiled for a longer time in sodium dodecylsulphate (SDS) it dissociated into two subunits with molecular masses of about 19 and 23 kDa. The 87 kDa form of the protein was able to increase the specific conductance of artificial lipid bilayer membranes from phosphatidylcholine (PC) phosphatidylserine (PS) mixtures by the formation of ion-permeable channels. The channels had on average a single-channel conductance of 3.0 nS in 1M KCl, 10mM Tris-HCl, pH8, and were found to be cation selective. Asymmetric addition of the cell wall porin to lipid bilayer membranes resulted in an asymmetric voltage dependence. The single-channel conductance was only moderately dependent on the bulk aqueous KCl concentration, which indicated point charge effects on the channel properties. The analysis of the single-channel conductance data in different salt solutions using the Renkin correction factor, and the effect of negative charges on channel conductance suggested that the diameter of the cell wall porin is about 1.4-1.6nm. Channel-forming properties of the cell wall porin of N. farcinica were compared with those of mycobacteria and corynebacteria. The cell wall porins of these members of the order Actinomycetales share common features because they form large and water-filled channels that contain negative point charges.

Hundredth molar calcium chloride extraction procedure. part II: Calibration with conventional soil testing methods for pH

Soil pH is probably the most important, single, parameter characterizing its fertility. For theoretical and practical reasons the soil pH is usually measured in salt solutions of different strength. The most common solution used in Europe is 1M potassium chloride (KCl) in a soil/solution ratio of 1:2.5 (W/V). The ultimate goal of the international project Copernicus of the European Community is to develop a uniform soil testing program based on the universal 0.01M calcium chloride (CaCl2)‐extraction procedure. In the Czech Republic, Hungary, The Netherlands, and Poland over 2,500 samples of representative soils have been collected and analyzed for soil pH in 1M KC1 and 0.01M CaCl2. Statistical analysis of these data shows a close correlation between pH values in both extracts. In very acid and acid soils, the pH in 0.01M CaCl2 is higher than in 1M KCl. In neutral and alkaline soils, there is no significant difference in soil pH measured by both methods. Soil samples from all countries present the same population in respect to the relation between soil pH in KCl and CaCl2.

Archaeal histone stability, DNA binding, and transcription inhibition above 90 degrees C.

The DNA binding and compacting activities of the recombinant (r) archaeal histones rHMfA and rHMfB from Methanothermus fervidus, and rHPyA1 from Pyrococcus species GB-3a, synthesized in Escherichia coli, have been shown to be completely resistant to incubation for 4h at 95 degrees C in the presence of 1M KCl. Continued incubation of rHMfA and rHMfB at 95 degrees C resulted in a gradual loss of these activities, and rHMfA and rHMfB lost activity more rapidly at 95 degrees C when the salt environment was reduced to 200 mM K Cl. rHPyA1, in contrast, retained full activity even after a 60-h incubation at 95 degrees C in 1 M KCl, and reducing the salt concentration did not affect the heat resistance of rHPyA1. rHPya1-DNA complexes remained intact at 100 degrees C, and rHPyA1 bound to the template DNA in in vitro transcription reaction mixtures assembled using Pyrococcus furiosus components at 90 degrees C. Transcription in vitro from the P. furiosus gdh promoter was reduced by rHPyA1 binding, in a manner that was dependent on the histone-to-DNA ratio and on the topology of the DNA template. Transcription from circular templates was more sensitive to rHPyA1 binding than transcription from a linear template, consistent with rHPyA1 binding introducing physical barriers to transcription and causing changes in the topology of circular templates that also reduced transcription.

Extraction and Stabilization of Mammalian CDP-Diacylglycerol Synthase Activity

CDP-diacylglycerol synthase, also known as CTP: phosphatidic acid cytidylyltransferase (EC 2.7.7.41), is thought to be the rate-limiting enzyme in the synthesis of the inositol phospholipids, phosphatidylglycerol and cardiolipin. Its role in inositol phospholipid synthesis suggests its potential as a regulator of signal transduction as well. Although the mammalian cDNA for the synthase has recently been cloned, attempts to purify this enzyme from a mammalian source have been unsuccessful due to its lability in detergents. We report here the extraction and stabilization of CDP-diacylglycerol synthase from rat liver. Using a buffer containing 2M KCl, we were able to extract virtually all of the activity from microsomal membranes. This extract was stable indefinitely at −72°C and for at least 24 hrs at 4°C. Incubation at room temperature for 24 hours resulted in the loss of more than half the activity. All detergents tested destroyed the activity. The activity was dependent on both substrates (phosphatidic acid and CTP) as well as on MgCl2, and inhibited by the product, CDP-diacylglycerol. Addition of GTP enhanced the activity approximately 2 fold, and bovine serum albumin increased activity by 6 fold.

Interaction of natrolite and thomsonite intergrowths with aqueous solutions of different initial pH values at 25°C in the presence of KCl: Reaction mechanisms

Natural zeolitic material composed of natrolite and thomsonite intergrowths (NAT/THO) was treated in solutions of different initial pH values at 25°C under N 2 atmosphere and in 1M KCl as ionic modulator, until pH equilibration. The solid experimental products were studied by means of powder X-ray diffraction (XRD), scanning electron microscopy-energy dispersive system (SEM-EDS), Fourier-transformed infra-red (FTIR) and thermogravimetric analysis/differential thermal analysis (TGA/DTA). The liquid experimental products were analysed using atomic absorption spectroscopy (AAS) and atomic emission spectroscopy (AES). The NAT/THO material exhibited an amphoteric character with a tendency to neutralise the reacting solutions. The pH equilibration was faster for the acidic region than for the basic one. The H + ions are chemisorbed on the bulk material, whereas the OH − ions promote a proton detachment from the exchangable cation-water complexes. No Brœnsted acidity, possibly responsible for the neutralisation in the basic region, was found by temperature-programmed desorption (TPD) measurements. Reaction mechanisms involving hydrolysis and degradation-dissolution are proposed. Zeolite crystals remaining at the end of the experiments showed no loss of crystallinity, phase transformation nor even framework dealumination. The insertion of K + into the zeolites is suggested here as the reason as to why no collapse of their crystal structure occurred in the most acidic solutions causing the zeolites to be more resistant to chemical weathering.

DEXAMETHASONE INDUCED LEFT VENTRICULAR HYPERTROPHY OF THE NEONATAL RAT MYOCARDIUM. † 173

Dexamethasone (dex) is a synthetic glucocorticoid which improves pulmonary function in infants with bronchopulmonary dysplasia. Some infants experience adverse effects including myocardial hypertrophy. We have previously shown that rat pups given therapeutic daily doses of dex develop myocardial hypertrophy using both gross and biochemical measures of cardiac mass. This experiment was designed to study the in vivo histologic effects of dex on neonatal rat myocardium. Newborn Sprague-Dawley rats were randomly assigned to the treatment group (dex 0.125 mg/kg/day IP injection) while paired littermates receiving placebo served as controls. Daily body weight for each pup was recorded and the pups sacrificed after 7 days. The hearts were removed, weighed, and rinsed in 150mM NaCl followed by 1M KCl to relax the myocardium, prior to fixation in a 2% paraformaldehyde solution. A random sample of control and dex exposed hearts were embedded in paraflin and 3 μm cross-sections taken at the bi-ventricular level. Three sections from each heart, mounted and stained with hematoxylin and eosin for standard light microscopy were examined by a pathologist in a blinded study. Measurements of left ventricular(LV), right ventricular(RV), and septal thickness(SP) were taken at 10x magnification. The cross-sectional surface area(SA) of the sample was determined using the NIH Image Analyzer program. These values were normalized to heart weight(HW) for comparison. The number of myocyte nuclei per hpf (NN) taken at 100x magnification and the length of nuclei (NS) were determined. Groups were compared by t-test with all data presented as mean±SD (* denotes significance p<0.05). Table

Comparison of soil nitrate extracted by potassium chloride and adsorbed on an anion exchange membrane in situ

Abstract The 2M potassium chloride (KCl) extraction method used to measure soil nitrate (NO3 ‐‐N) concentrations in soils may introduce some artifacts caused by soil sampling, processing, and handling. Furthermore, this method provides soil NO3 ‐‐N concentrations for soil sampled at a particular time, whereas the dynamics of this anion in situ need to be better understood. In order to develop a reliable in situ method as an alternative, an anion exchange membrane (AEM) was tested for its ability to adsorb NO3 ‐‐N from a soil cropped to corn (Zea mays L.) and amended with manure or inorganic nitrogen (N). In a field study, we compared the amount of NO3 ‐‐N adsorbed on an AEM and extracted with the 2M KCl method. The AEM was calibrated in the laboratory and placed at 15‐cm soil depth for 2‐wk periods during the corn growing season. Nitrate adsorption on the AEM and KCl‐extractable NO3 ‐‐N were larger in the inorganic N treatment than in the manure or the control treatments throughout the growing season. The...

Bray and Kurtz phosphorus (p1), 1m potassium chloride, and saturated calcium oxide extraction of soil nitrate comparison to 2m potassium chloride

Abstract Labor and laboratory expense could be reduce if soil extractable nitrate (NO3) was extracted simultaneously with other routinely used soil extractants. This study was conducted to compare 1M potassium chloride (KCl), saturated calcium oxide (CaO), and Bray and Kurtz P1‐extractable soil NO3, the proposed new method to 2M KCl. Nitrate was extracted from 140 selected soils with 1M KCl, saturated CaO, Bray and Kurtz P1, and 2M KCl extractants and analysed by cadmium reduction with a flow injection analyser. Nitrate extracted with 2M KCl was used as the standard. When 1M KCl, saturated CaO, and Bray and Kurtz P1 was regressed against 2M KCl, the slopes were equal to 1.0 and the intercepts were equal to 0.0 with r2>0.99. No detectable differences in extractable NO3 were measured between 1M KCl, saturated CaO, Bray and Kurtz Pl, and 2M KCl extraction procedures. Bray and Kurtz P1 can be used to simultaneously extract phosphorus (P) and NO3.

Soil aluminium extraction methods in relation to plant aluminium and yield on Austrian and Brazilian soils

Abstract A pot experiment with soils from Austria (Mollisol and Alfisol) and Brazil (two Oxisols), quite different in pH values and organic carbon contents, was carried out. Several soil tests for aluminum (Al) were evaluated and compared for their ability in predicting plant growth reductions and plant Al concentrations. Concerning the efficacy of the extradants in solubilizing soil Al, the amount of Al extracted decreased in the following order: 0.03M LaCl3> 1M KCl > 1M NH4Cl > 0.01 M CaCl2. Only AlCaCl2 and Al saturation correlated significantly with shoot yield of Poa pratensis (r = 0.76*** for CaCl2; r = 0.84 *** for Al saturation) and Phaseolus vulgaris (r = 0.65** for CaCl2; r = 0.83** for Al saturation). The results indicated that soil organic matter and the nutrient status of the soil had an important effect as diminishing Al uptake and improving growth of both Poa pratensis and Phaseolus vulgaris. Interactions between Al and magnesium (Mg) were also observed.

Retention and chemistry of aluminium in groundwater discharge areas

The concentration of different fractions of Al were measured in seven micro (3–4 m 2) discharge areas using extraction methods on the upper layer of the soil. The areas were situated in two catchments subjected to different levels of acidic deposition. The Al fractions were determined by separate extractions with 1m KCl, 0·5m CuCl 2 and 0·2 m (NH 4) 2C 2O 4. The fractions associated with the different extraction reagents are preferentially exchangeable, organically bound and amorphous hydroxide, although a complete separation cannot be made. The total amount of Al was determined after dry ashing. The results show that the levels of total Al in the peat were high when compared to ombrotrophic peatlands. The quantity and characteristics of the organic material and the acidity of the soils in the discharge zone could be decisive in determining which fractions of Al occur. The high levels of total Al in the soil indicate that the discharge zone could be an important trap for the element.

Interaction of urea with triple superphosphate in a simulated fertilizer band

Fertilizer nutrient diffusion from fertilizer bands and transformations in soil can affect fertilizer nutrient availability to crops and knowledge of the transformations is necessary for proper management. The interaction of urea and triple superphosphate (TSP) on urea hydrolysis and P transformations during diffusion processes from a fertilizer band was evaluated in a laboratory incubation experiment with two eastern Canadian soils (Ste Rosalie clay, Modifiers Typic Humaquept, pH 5.0; Ormstown silty clay loam, Modifiers Typic Humaquept, pH 6.0). Two fertilizer sources (urea and TSP) and three N and P rates (0, 100 and 200 kg ha−1) were combined in a factorial arrangement. Fertilizer combinations were placed on segmented soil columns, incubated and segments were analyzed for N and P content. Acidification from dissolution of TSP retarded urea hydrolysis, and curtailed the rise in soil pH surrounding the fertilizer band. Urea hydrolysis caused dissolution of organic matter in soils, which might inhibit precipitation of insoluble phosphates. Banding urea with TSP increased 1M KCl extractable soil P, soil solution P, sorbed P concentration and total P diffused away from the band. Urea decreased 0.01M CaCl2 extractable P, indicating probable precipitation of calcium phosphates with CaCl2 extraction. Banding urea with TSP could benefit P diffusion to plant roots in low Ca soils and increase fertilizer P availability.