Effects of organic matter on sulphur oxidation in soil and influence of sulphur oxidation on soil nitrification

Summary The effects of wheat straw and pressed sugar beet pulp on sulphur oxidation were determined in a loam soil amended with 1% (w/w) elemental sulphur. Wheat straw stimulated the oxidation of elemental sulphur over the first 2 to 3 weeks of the incubation period, resulting in an increase in LiCl-extractable sulphate. After 4 to 7 weeks incubation however, the only significant increase in soil sulphate followed the 1% straw addition, while at week 7 sulphate concentrations in the 0.25% and 5.0% straw amended soils were lower than the control. Pressed sugar beet pulp (1% w/w) initially stimulated the oxidation of elemental sulphur in the soil, but by weeks 3 to 7 of the incubation period rates of oxidation in pulp-amended soils were lower than the control. Towards the end of the incubation period however, sulphate concentrations in the amended soils exceeded the control values, significantly so by week 11. The concentration of thiosulphate and tetrathionate also increased in soils receiving sugar beet pulp. Nitrification was inhibited in soils in which sulphur oxidation was actively occurring. Although possible alternatives are mentioned, such inhibition appears to result from a decrease in soil pH brought about by the oxidation of elemental sulphur to sulphuric acid.     

Ion uptake in Pinus banksiana treated with sodium chloride and sodium sulphate

Within its wide range across Canada, jack pine is exposed to salinity from both natural and anthropogenic sources. To compare the effects of Cl and SO₄ on salt injury, sand and solution-culture grown jack pine ( Pinus banksiana Lamb.) seedlings were treated with nutrient solutions containing 60 or 120 m M NaCl, 60 m M Na₂SO₄, or a mixture of 60 m M NaCl and 30 m M Na₂SO₄. After 5 weeks of salt treatments, concentrations of Cl, K, Na, and SO₄ were determined in roots, stem and needles of the current and previous years growth, and in necrotic needles. To determine the role of water uptake in the absorption and translocation of salts in plants, total transpiration was measured as the loss of water from a sealed system and related to total plant uptake of Cl, Na, and SO₄. Sodium uptake and root-to-shoot transport rates were greater in treatments containing Cl. A delay in root-to-shoot transport of both Na and Cl indicates retention of these ions in the roots. Electrolyte leakage of needles was more closely related to treatment Cl concentrations than treatment Na concentrations. The transport of Na ions to the shoot was related to the presence of Cl, but was not related to transpiration rate.     

Microbial oxidation of elemental sulphur in brown soil

Plant and Soil - Brown soil formed from loamy clay was examined for its ability to produce sulphate from added elemental suphur. At higher rates of sulphur applications the pH of a slightly acid...     

Antioxidative responses of Ocimum basilicum to sodium chloride or sodium sulphate salinization

Soils and ground water in nature are dominated by chloride and sulphate salts. There have been several studies concerning NaCl salinity, however, little is known about the Na₂SO₄ one. The effects on antioxidative activities of chloride or sodium sulphate in terms of the same Na⁺ equivalents (25 mM Na₂SO₄ and 50 mM NaCl) were studied on 30 day-old plants of Ocimum basilicum L., variety Genovese subjected to 15 and 30 days of treatment. Growth, thiobarbituric acid reactive substances (TBARS), relative ion leakage ratio (RLR), hydrogen peroxide (H₂O₂), ascorbate and glutathione contents as well as the activities of ascorbate peroxidase (APX, EC 1.11.1.11); glutathione reductase (GR, EC 1.6.4.2) and peroxidases (POD, EC 1.11.1.7) were determined. In leaves, growth was more depressed by 25 mM Na₂SO₄ than 50 mM NaCl. The higher sensitivity of basil to Na₂SO₄ was associated with an enhanced accumulation of H₂O₂, an inhibition of APX, GR and POD activities (with the exception of POD under the 30-day-treatment) and a lower regeneration of reduced ascorbate (AsA) and reduced glutathione (GSH). However, the changes in the antioxidant metabolism were enough to limit oxidative damage, explaining the fact that RLR and TBARS levels were unchanged under both Na₂SO₄ and NaCl treatment. Moreover, for both salts the 30-day-treatment reduced H₂O₂ accumulation, unchanged RLR and TBARS levels, and enhanced the levels of antioxidants and antioxidative enzymes, thus achieving an adaptation mechanism against reactive oxygen species.     

氯化钠含量对黑翅土白蚁生存的影响

【目的】为摸清堤坝土埝中氯化钠对黑翅土白蚁Odontotermes formosanus Shiraki生存的影响,合理确定防治黑翅土白蚁危害堤坝的氯化钠含量值,确保堤坝工程安全运行。【方法】选取有黑翅土白蚁生存和无黑翅土白蚁生存两类堤坝的土埝,进行土埝中氯化钠含量的测试。【结果】有黑翅土白蚁生存的堤坝土埝氯化钠含量在0.02%以下,无黑翅土白蚁生存的堤坝土埝氯化钠含量在0.19%以上。【结论】研究成果对黑翅土白蚁危害堤坝的防治具有很好的实用价值。     

The response of lucerne (Medicago sativa L.) to sodium sulphate and chloride salinity

Sodium and sulphate-dominated salinity is a serious environmental problem occurring in soils and groundwater in many parts of the world. The effect of Na2SO4 and NaCl, at electrical conductivity levels ranging from 2 to 17 dS m-1, on the growth and tissue ion concentrations of 16 lines of lucerne (Medicago sativa L.) was examined in the greenhouse over a 2 month period. Averaged across all lines, plants grown at 17 dS m-1 produced 66% of the dry matter of plants grown at 2 dS m-1. However there were significant differences among lines in relative salt tolerance (as defined by the slope of the reduction in dry matter) versus electrical conductivity. Dry matter production was negatively correlated with shoot concentrations of Na+, Cl- and S2- and generally lines that were more tolerant to salinity had lower concentrations of those ions in the shoots. We conclude that lucerne is moderately tolerant to Na2SO4 -predominated salinity, and that the degree of intraspecific variation that exists within this species will allow more tolerant lines to be selected for establishment in conditions where sulphate salinity is a problem.Collaborator     

The effect of sodium chloride on solute potential and proline accumulation in soybean leaves

Two cultivars of soybean (Glycine max [L.] Merr.) were grown in solution with up to 100 millimolar NaCl. Leaf solute potential was −1.1 to −1.2 megapascals in both cultivars without NaCl. At 100 millimolar NaCl leaf solute potential was −3.1 to −3.5 megapascals in Bragg and −1.7 megapascals in Ransom. The decrease in solute potential was essentially proportional to the concentration of NaCl. In both salt susceptible Bragg and salt semitolerant Ransom, leaf proline was no more than 0.4 micromole per gram fresh weight at or below 20 millimolar NaCl. At 40 and 60 millimolar NaCl, Bragg leaf proline levels were near 1.2 and 1.9 micromoles per gram fresh weight, respectively. Proline did not exceed 0.5 micromole per gram fresh weight in Ransom even at 100 millimolar NaCl. Proline accumulated in Bragg only after stress was severe enough to induce injury; therefore proline accumulation is not a sensitive indicator of salt stress in soybean plants.     

Metabolism of surfactants sodium undecyltriethoxy sulphate and sodium dodecyltriethoxy sulphate in the rat

The metabolic fates of the synthetic surfactants, sodium [1-¹⁴C]undecyltriethoxy sulphate and sodium [1-¹⁴C]dodecyltriethoxy sulphate were studied in the rat. Both compounds were extensively metabolized regardless of the route of administration, oral, intraperitoneal or intravenous. Short-chain radioactive products were eliminated in the urine: the major metabolite of the dodecyl homologue in the urine was identified as ⁻O₂C¹⁴CH₂- (OC₂H₄)₃OSO₃⁻ by n.m.r. and g.l.c.–mass spectrometry, whereas the major metabolite of the undecyl homologue in the urine was tentatively identified as ⁻O₂CCH₂¹⁴CH₂- (OC₂H₄)₃OSO₃⁻. In contrast with experiments with the dodecyl derivative, when [1-¹⁴C]undecyltriethoxy sulphate was administered to rats, appreciable amounts of radioactivity were recovered as ¹⁴CO₂ in expired air. Whole-body radioautography implicated the liver as the major site of metabolism of both surfactants. The nature of the metabolic products establishes that both compounds are degraded by ω,β-oxidation. Cleavage of the ether linkage proximal to the sulphate moiety may account for the small amounts of ¹⁴CO₂ recovered in expired air after the administration of [1-¹⁴C]dodecyltriethoxy sulphate. It is suggested the substantial amounts of ¹⁴CO₂ recovered after [1-¹⁴C]-undecyltriethoxy sulphate administration originate from ⁻O₂¹⁴C(OC₂H₄)₃ OSO₃⁻, an unstable product of ω,β-oxidation. An n.m.r. spectrum of the metabolite identified as 2-(triethoxy sulphate)acetic acid and a mass spectrum of the trimethylsilyl derivative of the parent alcohol of that metabolite have been deposited as Supplementary Publication SUP50086 (5 pages) at the British Library Lending Division, Boston Spa, Wetherby, West Yorkshire LS23 7BQ, U.K., from whom copies can be obtained on the terms indicated in Biochem. J. (1978) 169, 5.