Formation of hydroxy‐sulfates from pyrite in coastal acid sulfate soil environments in Malaysia

Abstract

Pyrite in hydromorphic soils is oxidized when it is exposed to the atmosphere. The sulfide oxidation releases hydrogen (H⁺) ions and other ions into the aqueous solution, and subsequently hydroxy‐sulfates are formed. A laboratory aging experiment was conducted using coastal sulfate‐rich soils in Malaysia to identify and determine the nature and composition of the hydroxy‐sulfates and to explain the mechanism of their formation. Powder X‐ray diffraction (XRD) analysis showed that incubating the pyrite‐bearing soils in the presence of added electrolyte (KCl and NaCl) resulted in the formation of jarosite, natrojarosite, and/or alunite. Subsequent transmission electron microscopy‐energy dispersive X‐ray (TEM‐EDAX) analysis showed that a hydroxy‐sulfate crystal was composed mainly of hydrogen (H), oxygen (O), sodium (Na), aluminum (Al), sulfur (S), potassium (K), and iron (Fe) which was accounted for as jarosite, natrojarosite, and/or alunite by powder XRD. The small amount of fluorine (F), nickel (Ni), titanium (Ti), and manganese (Mn) occurring within the same hydroxy‐sulfate crystal was presumably originated from pyrite. This result points to the formation of hydroxy‐sulfates in acid sulfate soils via psuedomorphic replacement of pyrite under an oxidizing environment.     

The infrared identification of a humo‐polysaccharide ester in soil humic acid

Abstract

Studies involving methylation, dissolution, infrared spectroscopy and gas‐liquid chromatography were conducted with humic compounds extracted from a Greenville loam and a Cecil sandy loam.

The results indicated that methylated humic acid and non‐methylated hymatomelanic acid have similar infrared characteristics, with intense C‐H absorption at 2980 ‐ 2920 cm^‐1, and strong C=0 stretching but with very weak C00^‐ stretching at 1720 and 1650 cm^‐1 respectively. Gas‐liquid chromatography yielded chromatograms, having the same number of components, appearing at similar retention times. Dissolution separated hymatomelanic acid into fraction A, with humic acid characteristics; and fraction B, a polysaccharide. This separation released the infrared carboxyl peak at 1650 cm^‐1 in fraction A.

It was concluded that hymatomelanic acid was a naturally occurring ester compound, composed of humic material in ester linkages with polysaccharide.     

Modeling of urea degradation in white and rosé wines by acid urease

The specific activity of a whole cell acid urease preparation was tested in five wines manufactured in the Apulia region of Italy in the 2003 vintage at both short and long treatment times, thus confirming the validity of the pseudo-first-order kinetic model to describe urea removal in real wines. The ratio between the experimental pseudo-first-order kinetic rate constant (kIe) for any real wine tested and that (kI) referred to a model wine solution having the same composition and pH reduced from about 0.21 to 0.02 as the overall content of phenolic compounds (P) increased from 109 to 853 g m-3 of gallic acid equivalent (GAE). The specific inhibitory effect of such compounds was explained by accounting for the equilibrium constant (KP) of the reaction of polyphenols with acid urease, which was found to be about 21 g of GAE m-3 for the real wines tested, whereas it ranged from about 16 to 45 g of GAE m-3 when the model wine solution was enriched with tannins extracted from grape seeds or skins, respectively. A sequential experimental procedure consisting of accelerated acid urease tests at high doses of enzyme followed by accelerated ethyl carbamate tests on the resulting acid urease treated wine was recommended to assess preliminarily the technoeconomic feasibility of the acid urease hydrolytic process for the wine of concern. Keywords: Acid urease; real and model wines; phenolics; pseudo-first-order kinetic rate constant; inhibitory effect; urea degradation kinetics.     

The role of free space calcium in the basipetal transport of indole‐3‐acetic acid in sunflower hypocotyls 1

Calcium has been reported to be involved in the basipetal transport of indole‐3‐acetic acid (IAA). It has been suggested that basipetal transport of IAA requires the influx of Ca²⁺ into the cytoplasm from the cell wall free space and that Ca²⁺ acts as a second messenger. Experiments were conducted to determine the interaction of free space Ca²⁺ with the basipetal transport of IAA. Four day old sunflower (Helianthus annus L. cv ‘Russian Mammoth') seedlings grown in 0.20 strength Hoagland's solution were either left intact or excised below the cotyledonary node to remove the meristem, the source of IAA in the shoot. After removal of the node, the plants were treated with or without 500 μM IAA in lanolin paste. After 24 h, 3 mm segments were cut from the hypocotyls and incubated in KCl. Solution Ca²⁺ concentration, representing free space Ca²⁺, increased when the source of IAA was removed. Plants which were provided a source of IAA, either endogenously or exogenously, had low levels of free space Ca²⁺. In a separate experiment, segments of sunflower hypocotyls were incubated in KCl solutions with or without 10 μM IAA. Free space Ca²⁺ was lower when the segments were incubated in solutions containing IAA. It was concluded that basipetal IAA transport resulted in low levels of Ca²⁺ in the free space, which supports the hypothesis that basipetal IAA transport has a requirement for the influx of Ca²⁺ from the free space into the cytoplasm.     

Effect of 2,3,5‐triiodobenzoic acid on calcium level in sunflower plants and incidence of bract necrosis

Experiments were conducted with sunflower (Helianthus annuus, L.) of two inbred lines and eight cultivars grown in the field, in pots in the greenhouse or growth chamber and in nutrient solution. Water solutions of 2,3,5‐triiodobenzoic (TIBA) were sprayed over the top of the plants or added to the nutrient solution TIBA treatment resulted in induction of bract necrosis in some plants, increasing the bract necrosis index with higher TIBA concentration. TIBA had little effect on element concentration in leaves but it decreased the levels of Ca, Mg and B in bracts of plants. At a low TIBA concentration (25 μM) in the nutrient solution, young plants growing in hydroponic solution at a low Ca level, the levels of Ca and Mg of young leaves were decreased but TIBA treatment did not affect significantly the levels of these elements in roots. Since TIBA produces both bract necrosis and lower Ca content in bracts, it is suggested that bract necrosis is a physiological disorder related with lower Ca levels existing in the bracts when plants are grown under stress conditions.     

Fatty acid composition of lipids in sea buckthorn (Hippophaë rhamnoides L.) berries of different origins

The oil content and fatty acid composition of berries from two subspecies of sea buckthorn (Hippopha? rhamnoides L.) were investigated. The berries of subsp. rhamnoides contained a higher proportion of oil in seeds (11.3% vs 7.3%, p < 0.01), berries (3.5% vs 2.1%, p < 0.001), and seedless parts (2.8% vs 1.7%, p < 0.01) than the berries of subsp. sinensis. Linoleic (18:2n-6) and alpha-linolenic acids (18:3n-3) comprised about 70% of seed oil fatty acids. Palmitoleic acid (16:1n-7), practically absent in the seed oil, comprised 12.1--39.0% of oil in pulp/peel and 8.9--31.0% of that in the whole berries. More linoleic acid (40.9% vs 39.1%) and less alpha-linolenic acid (26.6% vs 30.6%) was found in the seed oil of subsp. sinensis than in the seed oil of subsp. rhamnoides (p < 0.05). The proportion of palmitoleic acid was higher in the oil of berries of subsp. rhamnoides than the berries of subsp. sinensis (26.0% vs 21.5%, 0.05 < p < 0.1), but was vice versa with alpha-linolenic acid (8.8% vs 11.2%, 0.05 < p < 0.1). The proportions of alpha-linolenic acid correlated inversely with oleic and linoleic acids in the seed oil. In the oil of whole berries, the proportion of palmitoleic acid correlated negatively with the proportions of linoleic and alpha-linolenic acids.     

Zinc nutrition and levels of endogenous lndole‐3‐acetic acid in radish shoots

Radish (Raphanus sativus cv. Akamaru‐Hatsukadaikon) was grown for several experiments in a glasshouse with zinc (Zn) supply in the nutrient solution. Lack of Zn resulted in stunted growth and reduced leaf of radish shoots were observed. Two‐dimensional thin layer chromatography (TLC) and gas chromatography‐mass spectrometry (GC‐MS) analysis revealed the presence of endogenous indole‐3‐acetic acid (IAA) in Zn‐deficient radish shoots. An estimate has been made of alkali‐labile (1 and 7N NaOH) IAA in Zn‐deficient radish shoots with the use of gas chromatography (GC). The level of 7N NaOH‐labile IAA (peptidic + ester + free) and IN NaOH‐labile IAA (ester + free) in Zn‐deficient radish shoots was almost the same as that of control radish shoots. These results suggest that Zn nutrition did not affect the level of endogenous IAA in radish shoots.     

Extraction and reverse‐phase high‐pressure liquid chromatography of gibberellic acid in soil

Abstract

Several aqueous extractants buffered above pH 6.5 were evaluated for their ability to extract gibberellic acid from a Xerollic Calciorthid. More than 90% of the GA₃ added to soil was recovered with 0.01 M KH₂PO₄, pH 7.4. Gibberellic acid in soil extracts concentrated under vacuum was determined by reverse‐phase high‐pressure liquid chromatography (HPLC) by comparing the reproducible GA₃ peak areas with those of standards prepared in the same background solution.     

Importance of acid‐insoluble residue in plant analysis for total macro and micro elements

Abstract

Insoluble siliceous residues remaining after HNO₃/HClO₄ decomposition of the plant tissues National Bureau of Standards, standard reference materials spinach (Spinacea oleracea), orchard leaves and tomato leaves (Lycopersicon escuientum), contained varying quantities of the macro and micro elements Na, K, Mg, Ca, Mn, Fe, Cu and Zn. For the different samples with total element concentrations ranging from 11 μg/g (Cu in orchard leaves) to 45,000 μg/g (K in tomato leaves), residues contained element concentrations ranging from 0.05 to 88 times the respective concentrations in the samples. Contributions of residues to element concentrations in the plant tissues varied from 0.04 to 42% of the total concentrations. Overall, these constituted negligible (ca 0.1% for Mg and Ca), small (0.5% for Zn, Mn, K and 1% for Cu), and large (6% for Fe, 28% for Na) contributions depending on sample and analyte. Residue contributions to total element concentrations of plant tissues must be considered for reliable estimations of macro and micro elements.     

Determination and comparison of γ-aminobutyric acid (GABA) content in pu-erh and other types of Chinese tea

Two previous studies have reported that pu-erh tea contains a high level of γ-aminobutyric acid (GABA), which is the major inhibitory neurotransmitter in the central nervous system and has several physiological functions. However, two other researchers have demonstrated that the GABA content of several pu-erh teas was low. Due to the high value and health benefits of GABA, analysis of mass-produced pu-erh tea is necessary to determine whether it is actually enriched with GABA. A high-performance liquid chromatography (HPLC) method was developed for the determination of GABA in tea, the results of which were verified by amino acid analysis using an Amino Acid Analyzer (AAA). A total of 114 samples of various types of Chinese tea, including 62 pu-erh teas, 13 green teas, 8 oolong teas, 8 black teas, 3 white teas, 4 GABA teas, and 16 process samples from two industrial fermentations of pu-erh tea (including the raw material and the first to seventh turnings), were analyzed using HPLC. Statistical analysis demonstrated that the GABA content in pu-erh tea was significantly lower than that in other types of tea (p < 0.05) and that the GABA content decreased during industrial fermentation of pu-erh tea (p < 0.05). This mass analysis and comparison suggested GABA was not a major bioactive constituent and resolved the disagreement GABA content in pu-erh tea. In addition, the GABA content in white tea was found to be significantly higher than that in the other types of tea (p < 0.05), leading to the possibility of producing GABA-enriched white tea.     

Optimizing the molecular weight of oat β-glucan for in vitro bile acid binding and fermentation

A previous study showed β-glucan with low molecular weight (MW, 1.56×10(5) g/mol) bound more bile acid and produced greater amounts of short-chain fatty acids (SCFA) than did β-glucan with high MW (Mn=6.87×10(5) g/mol). In the current study, β-glucan extracted from oat flour was fractionated into six different MW levels (high MW, 7.09×10(5); low level 1 (L1), 3.48×10(5); L2, 2.42×10(5); L3, 1.61×10(5); L4, 0.87×10(5); and L5, 0.46×10(5) g/mol) and evaluated to find the optimum MW affecting in vitro bile acid binding and fermentation. The β-glucan fractions with 2.42×10(5)-1.61×10(5) g/mol (L2 and L3) bound the greatest amounts of bile acid. After 24 h of fermentation, no differences were found in total SCFA formation among L1, L2, L3, and L4 fractions; however, the high MW and L5 MW fractions produced lower amounts of total SCFA. Thus, the optimum MW of β-glucan to affect both hypocholesterolemic and antitumorigenic in vitro effects was in the range of 2.42×10(5)-1.61×10(5) g/mol. This MW range also was the most water-soluble among the MWs evaluated.     

Effects of Dibutyl phthalate and phthalic acid on chlorosis recovery in iron‐deficiency stressed sorghum cultivars

The effects of DBP (Dibutyl phthalate) and PA (Phthalic acid) supplied to the nutrient medium of Fe‐deficiency stressed sorghum cultivars, CSH‐5, 2077‐A, and CS‐3541 were examined. It was found that both the chemicals (50 mg/1) caused recovery of the cultivars CSH‐5 and 2077‐A in 4 days of treatment. Furthermore, the growth of roots, especially the adventitious roots, was increased by the chemicals.     

Contributions of separate reactions to the acid–base buffering of soils in brook floodplains (Central Forest State Reserve)

The acid–base buffering of gleyic gray-humus soils developed in brook floodplains and undisturbed southern-taiga landscapes has been characterized by the continuous potentiometric titration of soil water suspensions. During the interaction with an acid, the major amount of protons (>80%) is consumed for the displacement of exchangeable bases and the dissolution of Ca oxalates. In the O and AY horizons, Mn compounds make the major contribution (2–15%) to the acid buffering. The buffer reactions with the participation of Al compounds make up from 0.5 to 1–2% of the total buffering capacity, and the protonation of the surface OH groups of kaolinite consumes 2–3% of the total buffering capacity. The deprotonation of OH groups on the surface of Fe hydroxides (9–43%), the deprotonation of OH groups on the surface of illite crystals (3–19%), and the dissolution of unidentified aluminosilicates (9–14%) are the most significant buffer reactions whose contributions have been quantified during the interaction with a base. The contribution of the deprotonation of OH groups on the surface of kaolinite particles is lower (1–5%) because of the small specific surface area of this mineral, and that of the dissolution of Fe compounds is insignificant. In the AY horizon, the acid and base buffering of soil in the rhizosphere is higher than beyond the rhizosphere because of the higher contents of organic matter and nonsilicate Fe and Al compounds.     

Extraction of nonexchangeable potassium from soils with boiling one molar nitric acid: Evaluation of different modes of boiling the soil‐acid suspension

Abstract

The standardization of kind and extent of boiling during the course of extraction of potassium (K) from soil in strong acid medium is crucial for obtaining a reliable and reproducible estimate of the nonexchangeable K concentration in soil. In the present study, relationships among the amounts of K extracted by different modes of boiling soil‐acid mixture adopted, i.e., heating mantle, hot plate and burner were established. Irrespective of the dominant mineralogy of soils, boiling on hot plate gave higher estimate of K followed by heating mantle and lower values were observed in case of burner. Among the methods, boiling on heating mantle showed lower mean standard deviation (32.32 mg kg^‐1) and lower coefficient of variation (4.9%) followed by hot plate (SD=52.43 mg kg^‐1; CV=7.26%) and burner (SD=56.30 mg kg^‐1; CV=9.48%). Based on precision analysis, boiling of soil‐acid suspension on heating mantle and hot plate was found to be superior to that on gas burner in extracting nonexchangeable K from soils.     

Determination of total organic‐C in soils by an improved chromic acid digestion and spectrophotometric procedure

Abstract

An improvement to the Walkley‐Black wet digestion method for the rapid determination of organic carbon over the range 0.2–5.5% in air‐dry soil is described. It permits total recovery of the organic‐C in finely ground soil samples digested with the heat of dilution from mixing N K₂ Cr₂ O₇ with concentrated H₂SO₄. in test tubes followed by external heating from a hot‐plate digestor. The organic‐C concentrations are determined directly, as the Cr product in diluted soil digests, by absorptiometry at 600 nm with calibration against similarly treated sucrose standards in solution. For the soils tested, there were negligible interferences from carbonates, wood charcoal, coke, Fe⁺² and readily reducible Mn; Cl does not interfere with the organic‐C assay in non‐saline soils but for saline soils a correction based on 1/12 Cl^‐ assay of the soil is necessary. The present method is compared with Tabatabai and Bremner's dry combustion procedure and Allison's manometric adaptation for calcareous soils. The procedure described here does not require carbonate to be determined and is therefore simpler. In addition it is cheaper, faster and more effective in controlling interferences than dry combustion procedures.     

Production of a conjugated fatty acid by Bifidobacterium breve LMC520 from α-linolenic acid: conjugated linolenic acid (CLnA)

This study was performed to characterize natural CLnA isomer production by Bifidobacterium breve LMC520 of human origin in comparison to conjugated linoleic acid (CLA) production. B. breve LMC520 was found to be highly active in terms of CLnA production, of which the major portion was identified as cis-9,trans-11,cis-15 CLnA isomer by GC-MS and NMR analysis. B. breve LMC520 was incubated for 48 h using MRS medium (containing 0.05% L-cysteine · HCl) under different environmental conditions such as atmosphere, pH, and substrate concentration. The high conversion rate of α-linolenic acid (α-LNA) to CLnA (99%) was retained up to 2 mM α-LNA, and the production was proportionally increased nearly 7-fold with 8 mM by the 6 h of incubation under anaerobic conditions at a wide range of pH values (between 5 and 9). When α-LNA was compared with linoleic acid (LA) as a substrate for isomerization by B. breve LMC520, the conversion of α-LNA was higher than that of LA. These results demonstrated that specific CLnA isomer could be produced through active bacterial conversion at an optimized condition. Because many conjugated octadecatrienoic acids in nature are shown to play many positive roles, the noble isomer found in this study has potential as a functional source.     

Interactional effects of β-glucan, starch, and protein in heated oat slurries on viscosity and in vitro bile acid binding

Three major oat components, β-glucan, starch, and protein, and their interactions were evaluated for the impact on viscosity of heated oat slurries and in vitro bile acid binding. Oat flour from the experimental oat line "N979" (7.45% β-glucan) was mixed with water and heated to make oat slurry. Heated oat slurries were treated with α-amylase, lichenase, and/or proteinase to remove starch, β-glucan, and/or protein. Oat slurries treated with lichenase or lichenase combined with α-amylase and/or proteinase reduced the molecular weight of β-glucan. Heat and enzymatic treatment of oat slurries reduced the peak and final viscosities compared with the control. The control bound the least amount of bile acids (p < 0.05); heating of oat flour improved the binding. Heated oat slurries treated with lichenase or lichenase combined with α-amylase and/or proteinase bound the least amount of bile acid, indicating the contribution of β-glucan to binding. Oat slurries treated with proteinase or proteinase and α-amylase together improved the bile acid binding, indicating the possible contribution of protein to binding. These results illustrate that β-glucan was the major contributor to viscosity and in vitro bile acid binding in heated oat slurries; however, interactions with other components, such as protein and starch, indicate the importance of evaluating oat components as whole system.     

Nutrient uptake and residual effect of organic treatments applied to vegetable–rice system in an acid soil

Direct and residual effects of organic treatments and in combination with inorganic fertilizers applied to acid soils were studied in the okra–rice system. Among the treatments studied, vermicompost (V.C) and poultry manure improved soil pH and exhibited liming effect, whereas inorganic fertilizer decreased soil pH. Inorganic fertilizer contributed to 78% of net return in okra but the residual effect was observed in inorganic and V.C combination. Soil available nitrogen and potassium had increased at 100% recommended dose, compensated crop uptake at 75%, but depletion was observed at 50%. Uptake of nitrogen was higher for okra from inorganic fertilizer but higher phosphorus and potassium uptake from V.C was observed for rice. Organic treatments showed better correlation between soil pH and zinc (Zn) uptake by okra and significant residual effect on rice. But it reduced the solubility of iron (Fe) and its uptake by okra and indicated a negative correlation between pH and diethylene triamine penta acetic acid-extractable Fe²⁺.     

Effects of dietary α-linolenic acid (18:3n-3)/linoleic acid (18:2n-6) ratio on fatty acid metabolism in Murray cod (Maccullochella peelii peelii)

Global shortages in fish oil are forcing the aquaculture feed industry to use alternative oil sources, the use of which negatively affects the final fatty acid makeup of cultured fish. Thus, the modulation of fatty acid metabolism in cultured fish is the core of an intensive global research effort. The present study aimed to evaluate the effects of various dietary α-linolenic acid (ALA, 18:3n-3)/linoleic acid (LA, 18:2n-6) ratios in cultured fish. A feeding trial was implemented on the freshwater finfish Murray cod, in which fish were fed either a fish oil-based control diet or one of five fish oil-deprived experimental diets formulated to contain an ALA/LA ratio ranging from 0.3 to 2.9, but with a constant total C?? PUFA (ALA+LA) content. The whole-body fatty acid balance method was used to evaluate fish in vivo fatty acid metabolism. The results indicate that dietary ALA was more actively β-oxidized and bioconverted, whereas LA appears to be more efficiently deposited. LA was β-oxidized at a constant level (~36% of net intake) independent of dietary availability, whereas ALA was oxidized proportionally to dietary supply. The in vivo apparent Δ-6 desaturase activity on n-3 and n-6 PUFA exhibited an increasing and decreasing trend, respectively, in conjunction with the increasing dietary ALA/LA ratio, clearly indicating that this enzymatic activity is substrate dependent. However, the maximum Δ-6 desaturase activity acting on ALA peaked at the substrate level of 3.2186 (μmol g fish?1 day?1), suggesting that additional inclusion of ALA is not only wasteful but counterproductive in terms of n-3 LC-PUFA production. Despite a constant total supply of ALA+LA, the recorded total in vivo apparent Δ-6 desaturase activity on both substrates (ALA and LA) increased in synchrony with the ALA/LA ratio, peaking at 1.54, and a 3.2-fold greater Δ-6 desaturase affinity toward ALA over LA was recorded.