Enzymatic hydrolysis of ester sulphate in soil organic matter extracts

Summary A method of assessing the enzymatic hydrolysis of ester sulphate in soil organic matter was developed. Soil organic matter extracted using a mild, chelating resin extraction procedure was incubated with a sulphatase from Helix pomatia in 0.05 M sodium acetate buffer (pH 4–8) at 37°C for 2h and the sulphate released was determined by a high performance liquid chromatography-conductivity detector system. The effect of some soil factors on the enzymatic hydrolysis of ester sulphate was examined. The study showed that part of the ester sulphate in soil organic matter was biochemically reactive. In the three Podzols studied, the ester sulphate hydrolysed accounted for 2%–12% of the hydriodic acid-reducible organic sulphate extracted. The largest amount of hydrolysable ester sulphate was found in the soil with a low pH, high inorganic sulphate and high hydriodic acid-reducible organic sulphate.     

Retention of sulphate by an acid brown earth and its relationship with the atmospheric input of sulphur to forest vegetation

In soil samples of an acid brown earth the sulphate retention was studied as a function of sulphate concentration and pH of the soil solution. The soil under two forest covers (spruce and beech), has. shown distinct variation in its sulphate retention characteristics. The soil under spruce, due to the greater filtering action of vegetation, receives higher inputs of sulphate und hydrogen ions and shows higher amounts of retained sulphate. The uppermost 10 cm soil samples from both sites do not retain any sulphate when its concentration in the solution phase is increased. In samples from greater depths, the retention of sulphate is accompanied by a change in pH of the soil solution. The maximum retention occurs at pH 4, and soil samples from under beech retain higher amounts of sulphate than those under spruce for a corresponding depth and similar conditions of H⁺ addition. Desorption of newly retained sulphate followed in some samples the concentration relationship found in the adsorption experiment without any hysteresis, but the desorption of initially present sulphate indicates that two different forms of sulphate, weakly-and tightly-bound, may be existing in these soils.     

Effect of phosphate status and pH on sulphate sorption and desorption

For soils from tea estates in northern India, sulphate sorption was of a similar magnitude to, and sometimes exceeded, phosphate sorption. Only a small part of this relatively large sulphate sorption was caused by the low pH of these soils. Most was caused by increased negative charge as a result of prior reaction over many decades with phosphate fertilizers. This decreased sorption of both phosphate and sulphate, but the effect on phosphate was larger. This is compatible with a model in which the mean location of the charge on the adsorbed phosphate ions is closer to the surface than for sulphate. On soils of low phosphate status, sulphate desorption curves showed hysteresis; on soils of high phosphate status, they did not. Further, on soils of high phosphate status, displacement of sulphate by phosphate solutions was faster. We interpret these observations as showing that, for low phosphate status soils, sulphate ions penetrated the surface, but for high phosphate status soils it did not because the pathways by which sulphate diffuses into the adsorbing material were blocked. We also show that, with increasing soil phosphate status, phosphate solutions were less effective in displacing sorbed sulphate. We think this also occurred because reaction with phosphate had decreased the affinity for phosphate more than it decreased the affinity for sulphate.     

Effect of foliar and soil applications of zinc sulphate on zinc uptake,tree size,yield, and fruit quality of mango

To compare the effect of methods (foliar and soil) and rate of application of zinc sulphate on zinc and phosphorus uptake, tree size, yield and fruit quality of mango (Mangifera indica L.) cv. Dusheri, zinc sulphate was applied as a foliar spray application (0.25, 0.50, 1.0%) and soil (0.5, 1.0, 2.0 kg tree^‐1) treatments during the second week of October (during flower bud differentiation period). All the zinc sulphate treatments of soil and foliar spray were effective in increasing the leaf zinc concentrations above recommended adequate level of (>20 mg kg^‐1) whereas control trees maintained low leaf zinc concentrations (13.8 to 13.3 mg kg^‐1). The uptake of foliar‐applied zinc was more rapid than that of soil applied zinc. All the treatments of zinc sulphate except the foliar spray treatment of zinc sulphate (0.25%) significantly increased zinc concentrations in the fruit pulp as compared with those in the control trees. The percent increase in the stem girth of trees was highest with the soil application of zinc sulphate (0.5 kg tree¹) followed by foliar application of zinc sulphate (1.0%) as compared with all other treatments. The percent increase in the tree canopy volume was highest with the foliar application of zinc sulphate (1.0%) followed by soil application of zinc sulphate (1.0 kg tree¹) as compared with control and all other treatments. There was no significant (P<0.05) increase in yield, fruit size and weight, pulp or stone weight with any treatment of zinc sulphate. Total soluble solid (TSS) in the fruit was significantly higher (18.6%) with the treatment of soil application of zinc sulphate (0.5 kg tree¹) as compared with all other treatments of zinc sulphate and the control. Acid and sugar content of the fruit was not significantly affected by the foliar or soil application of zinc sulphate.     

连续施用硫酸钾镁肥对柑橘的效应

以柑为试验材料,采用短期定位试验,研究了施用硫酸钾镁肥料对柑效应的影响。结果表明,施用各种钾肥对柑鲜果产量有极显著增产效果,且能提高叶片中钾素含量。在施用氮磷肥基础上,施用硫酸钾镁肥的增产效应明显,经济效益最佳。在本试验中,与施硫酸钾相比较,施用氯化钾的果实Vc含量略有下降,可滴定酸含量略有提高。     

Role of soil redox in growth and fertilizer nitrogen uptake by rice in Thailand paddy soils

Abstract. In a laboratory study, ¹⁵N ammonium fertilizer uptake and rice growth was determined in a non-acid sulphate marine soil (Typic Tropaquept) and an acid sulphate soil (Sulfic Tropaquept). Acid sulphate sensitive (IR 26) and acid sulphate tolerant (IR 46) rice varieties were grown in soil suspensions incubated at four Eh levels (+500, +250, +50, and -150 mV) in microcosms for three weeks. The results showed that rice grown in non-acid sulphate marine soils gave slightly better dry matter weight of 1.8g/pot, greater ¹⁵N uptake of 12.8 mg N/pot, and higher total N uptake of 38.4 mg N/pot than under acid sulphate soil conditions indicating the non-acid marine soil is more favourable to rice culture. Growth as measured by weight of dry matter was significantly reduced from 2.1g/pot under oxidized condition (+500 mV) to 0.8g/pot under highly reduced condition (-150 mV). N uptake by rice was significantly reduced from 16.9 mg/pot at + 500 mV to 4.5 mg N/pot at -150 mV Total N uptake also decreased with decreasing Eh. Growth, ¹⁵N uptake and total N uptake by acid sulphate tolerant rice, IR 46 were significantly higher than the acid sulphate sensitive rice variety, IR 26. Under highly reduced soil conditions (-150 mV), growing rice in acid sulphate soil would require additions of lime, intermittent irrigation and/or mid season drainage in order to increase soil redox potential and remove toxic substances.     

Effect of liming and phosphate additions on sulphate leaching in soils

The effect of lime (CaCO₃) and phosphate additions on surface charge characteristics and their effect on the leaching of sulphate were examined for two soils (Patua loam and Tokomaru silt loam) which differed in their adsorption capacities for sulphate.
Incubation of soils with either CaCO₃ (0–600 mmol kg⁻¹) or phosphate (0-208 mmol kg⁻¹) resulted in a two- to five-fold increase in the net negative charge and a similar decrease in the adsorption of sulphate. The effect of either lime or phosphate addition on both the surface charge and sulphate adsorption was more pronounced for the allophanic Patua soil than for the Tokomaru soil containing mainly vermiculite.
In a column experiment, liming induced the leaching of sulphur either by the desorp-tion of adsorbed sulphate or by the mineralization of organic sulphur. During a miscible displacement study, addition of either CaCO₃ or phosphate resulted in an early breakthrough of sulphate in the leachate. In a pulse experiment, in which soils were incubated with sulphate (3.12 mmol kg⁻¹) for 1 week and subsequently leached with water, more added sulphate was lost in the leachate of the soils previously incubated with either CaCO₃ or phosphate.     

Sulphate sulphur concentration in vegetable crops,soil and ground water in the region affected by the sulphur dioxide emission from Płock oil refinery (central Poland)

Research was carried out in 1984–1990 in the region affected by the sulphur dioxide emission from one of the greatest oil refineries in Europe (P?ock, central Poland). The sulphate sulphur concentration in the vegetable crops (red beet, carrot, parsley, bean, cabbage and dill), the soil and in ground water was defined in selected allotment gardens of P?ock city and in a household garden located in the rural area about 25 km from the town. The highest amount of sulphate sulphur was found in the vegetable crops cultivated in the garden situated in the closest vicinity of the refinery. Sulphate sulphur contents harmful for plants (above 0.50 per cent d.m.) were noted in cabbage and carrot leaves in almost all the gardens (except one). The soil in all examined gardens was characterised by high sulphate sulphur concentration, which considerably exceeds the maximum amount admissible for light soils in Poland, i.e. 0.004 per cent Am. The sulphate sulphur concentration in ground water in all the gardens exceeded the highest permissible content in drinking water in Poland (200 mg^*dm^?3 of sulphate or about 67 mg^*dm^?3 of sulphate sulphur). The sulphate sulphur content in the soil and ground water was not significantly dependent on the garden's distance from the refinery. Generally, the abovenormal sulphate sulphur concentrations occurred quite universally in the examined region and they concerned all the considered environmental components (vegetable crops, soil, ground water) and all the gardens.     

Characterization of ester sulphate in a gypsum-amended podzol using an immobilized sulphatase reactor

An immobilized sulphatase reactor column was successfully used to determine the biochemical stability of ester sulphate in soil organic matter extracted from a podzol amended with gypsum. The sulphatase from Helix pomatia was covalently attached to controlled-porosity glass beads, and the immobilized enzyme was packed into a small glass column. The optimum pH, the time required to reach equilibrium, and the percentage of substrate consumed for the enzymatic hydrolysis of soil ester sulphate (pH 7.7, 90 min, 23–59%) were substantially different from those of p-nitrophenyl sulphate at similar concentrations of substrate (pH 7.0, 40 min, 99%). The striking difference in the biochemical stability and kinetic behaviour between soil ester sulphate and the simple synthetic substrate reflected their different chemical nature and structural features. The amounts of enzymatically hydrolysable (labile) ester sulphate in soil organic matter extracted from the podzol amended with gypsum at rates of 0, 50, and 200 kg S ha^-1 were significantly different (P=0.0004), being 0.5, 1.1, and 1.4 g S ml^-1 soil extract (or 5, 11, and 14 g S g^-1 soil), respectively. The labile ester sulphate was not correlated with the total hydriodic acid-reducible organic sulphate with the soil organic matter extracts but with the hydriodic acid-reducible organic sulphate: organic C ratio, which increased as a result of gypsum amendment. This study revealed that input of inorganic sulphate as gypsum substantially increased the accumulation of labile ester sulphate in a podzol.     

Mercury methylation by sulphate-reducing bacteria from sediments of an acid stressed lake

The role of freshwater sulphate-reducing bacteria in McHg production was examined by adding specific microbial inhibitors to anoxic lake sediments spiked with ²⁰³HgCl₂ and measuring net methylation. The effect of increased sulphate (such as would arise from acid deposition in the area) on the activity of sulphate-reducing bacteria both in terms of sulphate reduction rate and methylation of Hg was examined by adding sulphate to ²⁰³HgCl₂ spiked sediments. Sodium molybdate (10 mM), a specific inhibitor for sulphate-reducing bacteria, reduced the amount of MeHg produced from anoxic lake sediments by 75% compared with controls over a 7 d period. In contrast, 2-bromoethane sulfonic acid (15 mM), a specific inhibitor for methanogenic bacteria, did not alter the amount of McHg produced. Additions of sulphate that were “realistic” in terms of the normal range of the area (5 to 30 mg.L^?), increased the sulphate reduction rate of sediment slurries. However, in the experimental system, these additions did not stimulate McHg production. In our study, methylation of Hg in sediments was primarily due to the activity of sulphate-reducing bacteria. However, the methylation rate does not appear to be sensitive to the concentration of sulphate over the range typical of softwater, Precambrian Shield lakes. This could be due to reduced availability of Hg due to the formation of insoluble HgS or to the fact that the overall activity of sulphate reducers not being stimulated even if sulphate reduction rate is, or both.     

Determination of total sulphur and extractable sulphate in plant materials by inductively‐coupled plasma atomic emission spectrometry

Abstract

Total sulphur and extractable sulphate were determined in plant materials by inductively‐coupled plasma emission spectrometry. For total sulphur, plant material was digested in concentrated nitric acid only. For the sulphate determination, the plant material was extracted with water, sulphate was precipitated as barium sulphate, washed, and redissolved in (NH₄)₄‐EDTA. In the determination of sulphur no spectral interferences were observed, when using the 182.04 nm emission line. The data for total sulphur compared well with a set of certified reference plant samples. For extractable sulphate no such certified plant material is available, but it was established that the proposed procedure did not lead to losses nor interferences.     

Oxidation-induced leaching of sulphate and cations from acid sulphate soils

Leaching of sulphate and cations from horizon samples of two acid sulphate soils (0.9 to 1.6% S in subsoil) was studied in the laboratory. Samples were incubated and eluted with water at 20 °C and 5 °C until apparent exhaustion of leachable S resources. The leachates were analyzed for pH, SO₄-S, Fe, Al, Mn, K, Ca, Mg, and Na. Oxidation of sulphide was retarded at the lower temperature. From all the originally water-logged samples the sulphate formed was initially washed out with base cations (mainly with Mg), but the proportion of acid counter ions (predominantly Al) increased with proceeding oxidation and acid formation. In the most acid leachates, pH was 2.6 to 2.8. In the transition layer between reduced and oxidized horizons, sulphide oxidation had been going on for some time, and acid cations were the main counter ions for sulphate already at the beginning of the experiment. In the totally oxidized surface horizons, sulphate was leached only in moderate quantities, and the sum of cation equivalents (mainly base species) exceeded that of sulphate, suggesting some removal of other anions. Leaching losses in the laboratory experiment, corresponding to drainage-induced loading of waters in field experiments during the course of many decades, point out the environmental danger associated with deep drainage of potentially acid sulphate soils.     

Mineralization of sulphur in sulphoquinovose by forest soils

Surface soils from four watersheds located in the Coweeta Basin near Franklin, North Carolina were assayed for their capacity to mineralize sulphur in 6-sulphoquinovose. All soils rapidly converted S in this component of the plant sulpholipid to inorganic sulphate, a soluble (salt extractable) ester sulphate and an insoluble ester sulphate. Sulphur in this latter fraction was released by acidhydrolysis of soil residues at 121°C. Although maximum concentrations of S in each fraction varied with duration of incubation, rates of conversion of S into all fractions were highest during the first hour. Mineralization rates based upon sulphate release and total S released from sulphoquinovose are reported.     

Neutralization of Nitrate and Sulphate in Precipitation on the Eastern Mediterranean Coast of Spain. Implications for Acidification Risk

The results of two years of sampling in a network of 27 rainfall stations in the Valencian Community (Spain), show that most of the rain collected in the region, has a neutral or alkaline character, with a high mean concentration of calcium and sulphate in some of them. The network station distribution covers a range of distances from the sea, altitude, soil use and human activities (industrial, urban, agricultural). No correlation has been found between H⁺ and strong acidic anions (non marine sulphate and nitrate). Sulphate showed a high correlation with calcium. The spatial distribution of non marine sulphate, the ratio of marine sulphate to total sulphate, nitrate, calcium concentration and pH, showed that different concentrations of species are more related with geographical and meteorological characteristics than with proximity to industrial sources. The received amount of calcium and their neutralizing effect is used to predict the soil acidification risk in the area.     

Investigating the Provenance and Seasonal Variations in Sulphate Sulphur and Oxygen Isotopes of Central Roztocze River Water,SE Poland

The isotope composition of sulphur and oxygen were measured in water collected from the Central Roztocze (SE of Poland) rivers. The research focused mainly on the upper section of the Wieprz River, its confluences and springs and on two confluences of the Tanew River. The results proved that there are two sources of sulphate dissolved in water: the Cretaceous aquifer and soil within the catchment's area. Seasonal variation of the sulphate concentration together with sulphur and oxygen isotope composition was observed. The isotope composition of sulphate varied in water collected at the different locations of the same river. They are similar for sulphates in springs and rivers. The isotope composition of sulphate varied in water collected at the different locations of the same river. The δ³⁴S values of sulphates in the Wieprz River are the lowest (negative) in lower part of the river. It shows that the contribution of sulphate from spring water increases downstream. The low sulphate content and high δ³⁴S and δ¹⁸O value in sulphates was found downstream from dams. It may be the result of deficiency of oxygen in mud and the reduction in bacteria activity. The seasonal variations of the oxygen isotope composition in sulphate are significant in sulphates collected from rivers and from springs. They are caused by seasonal variations of the δ¹⁸O in water stored in the soil. The narrow range of the δ¹⁸O values for the sulphates extracted from springs at the same time means that the main source of sulphate in spring water are oxidising processes using the same source of oxygen in every location. The high sulphate content combined with the high δ³⁴S values of the sulphates in springs suggest, that the sulphates from Cretaceous aquifer were mixed with sulphates dissolved from the soil.     

在石灰性土壤上硫酸亚铁防治苹果黄叶病的研究

果树黄叶病(失绿症)是由于缺铁而引起的生理病害。这种病害在我国西北、华北等地区发病相当普遍,有的果园发病率竟达20%—60%,病重者甚至死亡。用无机铁盐来防治这种病害,迄今已有一百多年的历史了。但用硫酸亚铁来防治黄叶病的效果并不令人满意。     

土壤有机矿质复合体研究Ⅷ.分离钙键有机矿质复合体的浸提剂─-硫酸钠

土壤中通过钙键结合的有机矿质复合体是一种外圈配合物,硫酸钠中的ＳＯ＾２－４作为金属离子的配位体可以与复合体中的Ｃａ＾２＋形成配合物,破坏钙键复合体,并使腐殖质转变为腐殖酸钠盐,从而与铁铝键复合体分离。本文论证了硫酸钠破坏钙键复合体和浸提腐歼击质的能力,证明硫酸钠是区分２钙键复合体和铁铝键复合体的优良试剂;研究了用硫酸钠液分离钙键复合体的方法,并提出了连续浸提铁铝键复合体的后续浸提剂种类。     

Microbial contribution to sulphate mobilization after liming an acid forest soil

Sulphate release from unsterilized and γ-irradiation sterilized soil samples was studied in leaching funnels over a 22-week incubation period. In unsterilized soil samples, lime addition to the acid forest topsoil caused an immediate increase in extractable sulphate, but enhanced sulphate release rates were detectable only during the first 4 weeks of incubation. Soil samples from an adjacent five-year-old limed plot displayed significantly higher sulphate release rates than the control throughout the experiment. The cumulative amount of sulphate extracted from the unsterilized treatments was modelled with parabolic functions and reached 4.6%, 6.8% and 8.2% of the initial total S-contents of the control, the lime treatment and limed plot respectively. Mineral-N release was also greatest in the samples from the old limed plot while fresh lime additions reduced net N-mineralization due to microbial immobilization. In the sterilized samples, γ-irradiation initially caused an increase in extractable sulphate and ammonium which is mainly attributed to the destruction of microbial biomass. After the second week, no further differences in extractable sulphate were detectable between the treatments. After 22 weeks, between 7 and 9 mg SO₄^2? -S kg^?1 soil was released from the sterilized samples which was 25–50% of the respective amounts in the unsterilized samples. A similar relationship was found for N. The data indicate that even 5 years after lime addition the observed increased sulphate concentrations in the soil solution can be attributed to enhanced microbial activity.     

Regulation of enzymes involved in the sulphur-assimilatory pathway

The regulation of enzymes involved in sulphate assimilation in plants has been investigated. Extractable activity of ATP sulphurylase (the first enzyme of the assimilatory pathway) has been shown to be regulated by sulphate availability and O-acctylserine (OAS) supply. OAS addition to the medium increased extractable activity and was able, at least partially, to overcome the repression of extraclable activity observed by supply of sulphate and cysteine. Cysteine synthase, the final enzyme of the cysteine biosynthetic pathway, was not regulated under these conditions.