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.     

南昌市大气硫沉降的空间变化和来源（摘要）（英文）

[目的]探讨苔藓组织硫含量和雨水硫酸根浓度的相关性及南昌市大气硫的来源。[方法]在南昌市南昌大学北区、南昌大学前湖校区、电厂、梅岭4个采样点采集石生细叶小羽藓[Bryohaplocladium microphyllum（Hedw.）R.Watanabe et Iwats]样品29个,并在南昌电厂采集煤样9个,然后测定苔藓组织和煤的硫含量和硫同位素值。苔藓组织硫含量ω（S）（%,以干质量计）用元素分析仪（German）测定。苔藓硫同位素测定：采用艾氏卡试剂分离并转化为硫酸钡的方法制备样品,然后用连续流同位素质谱仪CF-IRMS测定硫同位素组成。测定数据采用以国际硫同位素CDT标准标定的国家硫同位素标准（硫化银）进行校正。[结果]南昌大学北区苔藓组织硫含量（0.45%±0.059%）高于南昌大学苔藓组织硫含量（0.26%±0.002%）,能反映南昌市雨水硫酸根浓度变化规律。南昌市苔藓硫同位素的变化范围是-0.64‰～9.71‰,其中南昌市市郊梅岭苔藓组织硫同位素值最高（4.02‰～9.71‰）,明显高于南昌大学前湖校区（0.55‰～0.56‰）和电厂苔藓组织硫同位素值（ -0.64‰～0.45‰）。[结论]对苔藓组织硫含量和硫同位素值相关性的研究表明,南昌市大气硫源主要受到中国北方远距离传输硫和生物成因硫的共同影响。     

硫在旱地土和水稻土中氧化的初步研究

研究了硫磺在旱地土和水稻土中的氧化特征。结果表明 :在培养 2 0～3 0d内硫磺的氧化速率最大 ,到 3 0d后基本达到稳定水平。在一定温度范围内 ,温度越高 ,氧化速率越大 ,3 0℃恒温条件下的氧化速率是 1 5℃恒温下的 2倍以上。湿润条件下的氧化速率比淹水条件下快近 2倍以上     

硫肥对两个不同穗型冬小麦品种光合特性及产量的影响

在大田土壤有效硫含量15.8 mg.kg^-1试验条件下，研究了不同硫肥处理对冬小麦多穗型品种豫麦49和大穗型品种豫麦66光合特性和产量的影响。结果表明，60 kg.hm^-2纯硫基施或基施与拔节期追施各50%处理与对照相比，提高了群体光合速率（CAP）、旗叶蒸腾速率（T_r），同时提高了叶片叶绿素（Chl）含量，尤其显著地提高了旗叶净光合速率（P_n），延缓了灌浆后期P_n的下降。施硫处理产量显著高于对照，以60 kg.hm^-2纯硫分基施与拔节期追施各50%处理效果最好。两品种光合特性和产量对不同硫肥处理的反应表现出差异，施硫对豫麦66旗叶光合速率的影响大于豫麦49。纯硫120 kg.hm^-2处理的光合特性指标和产量低于其他硫肥处理。据此，作者对两种穗型冬小麦品种合理施用硫肥的技术措施提出了建议。     

烟草硫素营养研究进展

硫是烟草必需的营养元素之一,是仅次于氮、磷、钾的第四要素。硫素对烟草的生长发育、烟叶的产量和品质有着重要的影响。就近年来国内外烟草硫素研究进展,包括国内主产烟区土壤硫含量的测定分析、烟株对硫元素的吸收利用、施硫对烟草产量和品质的作用等进行了综述,并就今后烟草硫素的研究方向谈了粗浅的看法。     

Impact of decreasing throughfall depositions on soil solution chemistry at coniferous monitoring sites in northern Belgium

Impact of decreasing throughfall depositions on soil solution chemistry at three depths was examined in a Corsican pine (Pinus nigra Arn. ssp. laricio Poiret) stand in Ravels and a Scots pine (Pinus sylvestris L.) stand in Brasschaat within a time-span of 6 years (1992–1997). At Ravels depositions of sulphate, ammonium, nitrate, calcium, magnesium and sodium decreased by 463, 468, 169, 121, 63 and 169 mol_c ha⁻¹ per annum. At Brasschaat deposition reduction rates of sulphate, nitrate, calcium and magnesium were 198, 127, 134 and 46 mol_c ha⁻¹ per annum. In both stands the substantial reductions in inorganic nitrogen deposition were followed by a decline of nitrate fluxes leaving the forest floor and with the seepage water. The decrease of sulphate deposition since 1992 was only manifested by a decline in sulphate concentrations and fluxes during the first half of the measuring period. The increase at the end of the period could be ascribed to the fact that sulphate adsorption which was important between 1993 and 1995 finally ceased. A significant drop of calcium concentrations was discernible at both plots. Magnesium and potassium levels did only fall significantly at Brasschaat. The concentrations of base cations were largely driven by the concentrations of their counter anions, but were influenced by the base cation throughfall fluxes as well. Although a substantial reduction of throughfall acidity occurred, no improvement of the soil water acidity (acid neutralising capacity (ANC)) was noticed. ANC and molar Ca/Al followed decreasing trends at all depths in both plots. For ANC the decline was significant for the topsoil in Ravels. The decrease of molar cation Ca/Al ratio was significant for two out of three depths at both sites. The decrease was due to the drop in calcium concentrations and the raise of Al_tot in some horizons.     

SO2对贮藏龙眼果皮酶促褐变的影响

以‘石硖’龙眼为材料，研究了ＳＯ２抑制贮藏期间龙眼果皮酶促褐变的机理。结果表明：ＳＯ２通过降低果皮细胞质的ｐＨ值，抑制多酚氧化酶酶活性，保存游离酚和总酚含量，保护还原型抗坏血酸等作用抑制了龙眼果实贮藏期间的褐变。     

日粮硫、镁水平对肉鸡血液酸碱平衡和胫骨软骨发育不良的影响

在玉米 豆粕日粮中,添加３ 个水平的Ｍｇ０ 和（ＮＨ４）２ＳＯ４ ,使日粮中的硫、镁水平分别达到０ ．４０ ％ 、０ ．６５ ％ 、０ ．９０ ％ 和０ ．１７ ％ 、０ ．３７ ％ 、０ ．５７ ％ ,组成９ 个处理日粮,饲喂４０５ 只艾维茵肉用公雏,研究日粮电解质平衡对２１ 日龄肉鸡生长性能、胫骨软骨发育不良（ＴＤ） 发生、血液酸碱平衡的影响。在一定范围内日粮高硫具有诱食作用。日粮高镁同时降低了采食量、日增重和饲料效率（Ｐ＜ ０ ．０５） 。日粮高硫明显降低了ＴＤ 发生率和生长板厚度（Ｐ＜ ０ ．０５） ,高镁则起到相反的作用。日粮电解质平衡与肉鸡ＴＤ 发生率呈线性负相关（Ｒ＝ － ０ ．８２５） 。虽然日粮镁、硫水平对血液ｐＨ 影响不显著,但日粮高硫降低了碱超和碱贮（Ｐ＜ ０ ．０５） ,酸化了血液;日粮高镁则增加了碱超（Ｐ＜ ０ ．０５） ,起到了碱化作用。试验结果表明,由日粮硫、镁水平调节的电解质平衡可能通过改变血液酸碱平衡,成为影响肉鸡胫骨软骨发育的重要因素。     

Effects of dietary Cu, Mo and S on urinary Cu and Zn excretion in Simmental and Angus cattle

This study determined the effects of dietary copper (Cu), molybdenum (Mo) and sulphur (S) on urinary Cu and zinc (Zn) excretion in cattle. Four Simmental and four Angus heifers were fed low (L) or high (H) levels (mg/kg DM) of Cu (5, 40), Mo (1, 10) and S (0.2, 0.5%). Initially two of each breed was fed either LCu or HCu (2 mo). Then all eight animals were fed sequentially LCuHS (1.5 mo), HCuHS, HCuHMo and HCuHMoHS (2 mo each). Simmental had a higher urine flow, increased concentration and total excretion of urinary Cu and Zn compared to Angus, but only total Zn excretion was significantly higher. Urinary Cu excretion was greatest with the HCuHMoHS diet. Urinary Zn excretion significantly increased with HS but not HS in combination with HMo and/or HCu. This study, together with previously reported biliary excretion, allows a direct comparison of urinary and biliary Cu and Zn excretion responses to dietary Cu, Mo and S.     

Long-term (13 years) measurements of SO2 fluxes over a forest and their control by surface chemistry

Long-term fluxes of sulphur dioxide (SO₂) have been measured over a mixed suburban forest subjected to elevated SO₂ concentrations. The net exchange was shown to be highly dynamic with substantial periods of both upward and downward fluxes observed in excellent conditions for flux measurement. Upward fluxes constituted 30% of selected fluxes and appeared more frequently when the canopy was acidic. Upward fluxes were shown to be due to desorption from a drying surface or when ambient levels declined after periods of increased SO₂ exposure.The long term average SO₂ flux (F) was −59 ng SO₂ m⁻² s⁻¹ for the period 1997-2009 corresponding to an average SO₂ concentration of 12.3 μg SO₂ m⁻³ and a deposition velocity υ_d of 5 mm s⁻¹. The smallest deposition fluxes and υ_d were measured in dry conditions (−42 ng m⁻² s⁻¹ and 3.5 mm s⁻¹, resp.), which represented 57% of all cases. Wet canopies were more efficient sinks for SO₂ and a dew-wetted canopy had a smaller υ_d (6 mm s⁻¹) than a rain-wetted canopy (ca 10 mm s⁻¹). Seasonal variability reflected differences in chemical climate or canopy buffering properties. During the summer half-year when surface acidity was low due to higher NH₃/SO₂ ratios, a higher deposition efficiency (υ_d/υ_dmax) and lower non-stomatal resistance (R_w) were observed compared to winter conditions. Comparisons of R_c for different combinations of canopy wetness and surface acidity categories emphasized the importance of both factors in regulating the non-stomatal sinks of SO₂. Increased surface water acidity gradually led to a lower υ_d/υ_dmax and an increased R_c for all considered canopy wetness categories. The smallest υ_d/υ_dmax ratio and highest R_c were obtained for a dry canopy with high surface acidity. Conversely, a rain-wetted canopy was the most efficient sink for SO₂. The canopy sink strength was further enhanced by high friction velocities (u_*), optimizing the mechanical mixing into the canopy. Long-term trends were strongly coupled to changes in the NH₃/SO₂ ratio, which has clearly enhanced the deposition efficiency of SO₂ in recent years.