The sulfur cycle

Even granting our uncertainties about parts of our model of the sulfur cycle, we can draw some conclusions from it: 1) Man is now contributing about one half as much as nature to the total atmospheric burden of sulfur compounds, but by A.D. 2000 he will be contributing about as much, and in the Northern Hemisphere alone he will be more than matching nature. 2) In industrialized regions he is overwhelming natural processes, and the removal processes are slow enough (several days, at least) so that the increased concentration is marked for hundreds to thousands of kilometers downwind. 3) Our main areas of uncertainty, and ones that demand immediate attention because of their importance to the regional air pollution question, are: (i) the rates of conversion of H(2)S and SO(2) to sulfate particles in polluted as well as unpolluted atmospheres; (ii) the efficiency of removal of sulfur compounds by precipitation in polluted air. And for a better understanding of the global model we need to know: (i) the amount of biogenic H(2)S that enters the atmosphere over the continents and coastal areas; (ii) means of distinguishing man-made and biogenic contributions to excess sulfate in air and precipitation; (iii) the volcanic production of sulfur compounds, and their influence on the particle concentration in the stratosphere; (iv) the large-scale atmospheric circulation patterns that exchange air between stratosphere and troposphere (although absolute amounts of sulfate particles involved are small relative to the lower tropospheric burden); (v) the role of the oceans as sources or sinks for SO(2).     

Large volcanic aerosol load in the stratosphere linked to Asian monsoon transport

The Nabro stratovolcano in Eritrea, northeastern Africa, erupted on 13 June 2011, injecting approximately 1.3 teragrams of sulfur dioxide (SO(2)) to altitudes of 9 to 14 kilometers in the upper troposphere, which resulted in a large aerosol enhancement in the stratosphere. The SO(2) was lofted into the lower stratosphere by deep convection and the circulation associated with the Asian summer monsoon while gradually converting to sulfate aerosol. This demonstrates that to affect climate, volcanic eruptions need not be strong enough to inject sulfur directly to the stratosphere.     

Sulfate Cooling Effect on Climate Through In-Cloud Oxidation of Anthropogenic SO2

Anthropogenic SO(2) emissions may exert a significant cooling effect on climate in the Northern Hemisphere through backscattering of solar radiation by sulfate particles. Earlier estimates of the sulfate climate forcing were based on a limited number of sulfate-scattering correlation measurements from which a high sulfate-scattering efficiency was derived. Model results suggest that cloud processing of air is the underlying mechanism. Aqueous phase oxidation of SO(2) into sulfate and the subsequent release of the dry aerosol by cloud evaporation render sulfate a much more efficient scatterer than through gas-phase SO(2) oxidation.     

Clouds of venus: a preliminary assessment of microstructure

The multimodal microstructure of the Venus cloud system has been examined. In addition to confirmed H(2)SO(4) droplets and suspected elemental sulfur, a highly concentrated aerosol population has been observed extending above, within, and below the cloud system. These aerosols appear to cycle through the cloud droplets, but can never be removed by the weak precipitation mechanisms present. All cloud particles are likely laced with aerosol contaminants. Sedimentation and decomposition of H(2)SO(4) in the droplets of the lower cloud region contribute more than 7 watts per square meter of heat flux equaling one-fourth of the solar net flux at 50 kilometers.     

单纯形优化法在混凝除磷试验中的应用研究

以天津市纪庄子污水厂二级出水作为研究对象,利用单纯形优化方法,探讨不同混凝剂优化混凝除磷的最优条件。本实验对两种混凝剂硫酸铁、硫酸铝的混凝除磷效果进行了研究,利用单纯形优化方法对两种混凝剂的主要影响因素(混凝剂投加量和pH)进行了优化,从而得出了两种混凝剂去除二级出水中磷的最优条件。结果表明:通过18～25次实验,单纯形即可确定两种混凝剂除磷的最优条件。每种混凝剂的去除率都至少增加了30%。硫酸铁、硫酸铝两种混凝剂对总磷的最大去除率分别为87.25%,95.60%。每种混凝剂对正磷酸盐的去除率大于总磷的去除率。硫酸铁、硫酸铝两种混凝剂除磷的总磷残余浓度分别为0.35 mg.L-1,0.12 mg.L-1,达到0.5 mg.L-1以下的城市污水再生利用景观环境用水水质标准(GB/T18921-2002)。     

不同钼水平对生长猪肝脏、肾脏亚硫酸氧化酶活性及尿中SO_3~(2-)、SO_4~(2-)的影响

在生长猪低钼低硒基础饲粮内,分别添加0、10、100ppm钼(钼酸铵),测定了猪肝、肾组织亚硫酸氧化酶活性、尿中SO_3~2-/SO_4~(2-)以及尿中SO_3~(2-)和SO_4~(2-)日排出量。结果初步表明:加钼能提高组织亚硫酸氧化酶活性,减少尿中SO_3~(2-)排出,提高SO_4~(2-)排出,降低尿中SO_2~(2-)/SO_4~(2-)。肝脏亚硫酸氧化酶活性与尿中SO_3~(2-)/SO_4~(2-)和SO_3~(2-)排出呈显著的强负相关,肾脏亚硫酸氧化酶活性与尿中SO_4~(2-)的排出量呈中等正相关。     

Oxygen isotope constraints on the sulfur cycle over the past 10 million years

Oxygen isotopes in marine sulfate (delta18O(SO4)) measured in marine barite show variability over the past 10 million years, including a 5 per mil decrease during the Plio-Pleistocene, with near-constant values during the Miocene that are slightly enriched over the modern ocean. A numerical model suggests that sea level fluctuations during Plio-Pleistocene glacial cycles affected the sulfur cycle by reducing the area of continental shelves and increasing the oxidative weathering of pyrite. The data also require that sulfate concentrations were 10 to 20% lower in the late Miocene than today.     

Hydrogen Sulfide on IO: Evidence from Telescopic and Laboratory Infrared Spectra

Evidence is reported for hydrogen sulfide (H(2)S) on Io's surface. An infrared band at 3.915 (+/- 0.015) micrometers in several ground-based spectra of Io can be accounted for by reflectance from H(2)S frost deposited on or cocondensed with sulfur dioxide (SO(2)) frost. Temporal variation in the occurrence and intensity of the band suggests that condensed H(2)S on Io's surface is transient, implying a similar variation of H(2)S abundance in Io's atmosphere. The band was observed in full-disk measurements of Io at several orbital longitudes, including once at 24 degrees ( approximately 0.5 hour after Io's reappearance after an eclipse)-but not after another reappearance at 22 degrees -and once at 95 degrees (on Io's leading hemisphere). These results suggest that condensed H(2)S is sparse and variable but can be widespread on Io's surface. When present, it would not only produce the infrared band but would brighten Io's typical surface at ultraviolet and visible wavelengths.     

水-乙醇-硫酸铵体系及在分离提取天然产物中的应用

水-乙醇-硫酸铵构成的双水相体系,具有不使用有毒有机溶剂、萃取条件温和的特点.使用测定上下相电导和折光的方法,测定了分相前乙醇含量为30%和40%的溶液分相后上下相的组成;上下相的组成和硫酸铵的加入量有关.分相前乙醇含量为40%的溶液,分相后上相的乙醇含量可达55%,同时上相中仍含约0.03 g/ml的硫酸铵;下相乙醇含量在10%左右,硫酸铵的含量约为0.45 g/ml.     

菹草内生硫氧化细菌的分离鉴定及对鸡粪中硫化氢的减释作用

鸡粪中的含硫有机物在微生物作用下会释放出大量的硫化氢气体,危害畜禽的健康及污染环境。试验以减少鸡粪中硫化氢释放量为目的,从菹草内分离得到1株具有异养硫氧化作用的细菌,命名为JS3。16S rRNA序列分析表明菌株JS3与杀鲑气单胞菌的亲源关系最近。以硫代硫酸钠为唯一硫源时菌株JS3的硫氧化特征:碳源优先利用顺序为葡萄糖柠檬酸钠乙酸钠;氮源优先利用顺序为硝酸钠氯化铵;菌株JS3氧化硫的最佳碳氮比为15∶1,此时77.82%的硫代硫酸根被转化为硫酸根;pH从4.05增加到10.05,菌株的氧化硫能力先增强后下降,当pH为9.05时,硫酸根的积累量最高,可达到4.33 g/L;当氯化钠添加量达到4.0%时对菌株JS3才产生明显影响,说明株菌具有一定的耐盐性;最佳硫代硫酸根初始浓度为2 810 mg/L,此时83.22%的硫代硫酸根被转化为硫酸根;250 mL三角瓶中装液量为75 mL时,菌株JS3是硫氧化能力最强。在硫化氢减释模拟试验中,与对照相比,菌株JS3可降低84.53%的硫化氢释放量。     

Physical Chemistry of the H2SO4/HNO3/H2O System: Implications for Polar Stratospheric Clouds

Polar stratospheric clouds (PSCs) play a key role in stratospheric ozone depletion. Surface-catalyzed reactions on PSC particles generate chlorine compounds that photolyze readily to yield chlorine radicals, which in turn destroy ozone very efficiently. The most prevalent PSCs form at temperatures several degrees above the ice frost point and are believed to consist of HNO(3) hydrates; however, their formation mechanism is unclear. Results of laboratory experiments are presented which indicate that the background stratospheric H(2)SO(4)/H(2)O aerosols provide an essential link in this mechanism: These liquid aerosols absorb significant amounts of HNO(3) vapor, leading most likely to the crystallization of nitric acid trihydrate (NAT). The frozen particles then grow to form PSCs by condensation of additional amounts of HNO(3) and H(2)O vapor. Furthermore, reaction probability measurements reveal that the chlorine radical precursors are formed readily at polar stratospheric temperatures not just on NAT and ice crystals, but also on liquid H(2)SO(4) solutions and on solid H(2)SO(4) hydrates. These results imply that the chlorine activation efficiency of the aerosol particles increases rapidly as the temperature approaches the ice frost point regardless of the phase or composition of the particles.     

玉米幼苗根系吸收硫酸盐(Na_2~(35)SO_4)效率与产量杂种优势的关系

本文以来源不同的９个自交系及其按双列杂交组成的３６个正交Ｆ１组合为材料， 研究了玉米幼苗根系吸收硫酸盐（Ｎａ３５２ＳＯ４）的动力学参数（Ｋｍ和Ｖｍａｘ）与产量杂 种优势（Ｈ）的关系·结果表明，Ｖｍａｘ与Ｈ无明显的数量关系，Ｋｍ与Ｈ间呈显著的 直线相关（ｒ＝－０．３３３１，Ｐ＜０．０５）．Ｋｍ可作为早期预测产量杂种优势的一个生理 参考指标。     

A mercury-catalyzed, high-yield system for the oxidation of methane to methanol

A homogeneous system for the selective, catalytic oxidation of methane to methanol via methyl bisulfate is reported. The net reaction catalyzed by mercuric ions, Hg(II), is the oxidation of methane by concentrated sulfuric acid to produce methyl bisulfate, water, and sulfur dioxide. The reaction is efficient. At a methane conversion of 50 percent, 85 percent selectivity to methyl bisulfate ( approximately 43 percent yield; the major side product is carbon dioxide) was achieved at a molar productivity of 10(-7) mole per cubic centimeter per second and Hg(II) turnover frequency of 10(-3) per second. Separate hydrolysis of methyl bisulfate and reoxidation of the sulfur dioxide with air provides a potentially practical scheme for the oxidation of methane to methanol with molecular oxygen. The primary steps of the Hg(II)-catalyzed reaction were individually examined and the essential elements of the mechanism were identified. The Hg(II) ion reacts with methane by an electrophilic displacement mechanism to produce an observable species, CH(3)HgOSO(3)H, 1. Under the reaction conditions, 1 readily decomposes to CH(3)OSO(3)H and the reduced mercurous species, Hg(2)(2+) The catalytic cycle is completed by the reoxidation of Hg(2)(2+) with H(2)SO(4) to regenerate Hg(II) and byproducts SO(2) and H(2)O. Thallium(III), palladium(II), and the cations of platinum and gold also oxidize methane to methyl bisulfate in sulfuric acid.     

Kuwait oil fires: correction

In our article "Airborne studies of the smoke from the Kuwait oil fires" (15 May, p. 987) (1), we stated that the depletions of sulfur dioxide (SO(2)) and nitrogen oxides (NO(x)) in the smoke plume from the Kuwait oil fires were 50 and 60% per hour, respectively. These values were derived from measurements made aboard a Convair C-131 aircraft, and measurements of CO(2) were used as a conserved tracer. Subsequent comparisons of these measurements of CO(2) (which were obtained from a continuous analyzer) with independent measurements of CO(2) (obtained from "grab" samples) revealed that the continuous CO(2) measurements were occasionally contaminated by cabin air. Recalculation of the depletion rates of SO(2) and NO(x), with the use of uncontaminated measurements of CO(2) from the "grab" sampler aboard the aircraft yielded values of 6 and 22%, respectively (2). Our conclusions with regard to the climatic effects of the Kuwait oil fires are unchanged.     

西吉县第三系承压水中硫酸盐的水文地球化学特征及其来源

宁夏自治区西吉县地下水中硫酸盐(SO₄^2-)含量普遍超标,为了查明地下水中SO₄^2-的来源,对区内36件地下水样品的水化学组成、21件岩石样品的易溶盐组分和10件地下水样品硫同位素组成进行了测试分析。结果表明：SO₄^2-是区内地下水中主要阴离子组分,在区域上具有北部低,中部和南部高的明显的分带性,并且沿着地下水流向SO₄^2-含量逐渐升高;SO₄^2-也是区内第三系地层中主要的易溶盐组分,以石膏和芒硝形式存在;区内地下水中SO₄^2-主要来源于地层中石膏和芒硝（所占比例平均为83%）,其次是地层中的硫化物（所占比例平均为17%）。     

Active microbial sulfur disproportionation in the Mesoproterozoic

The environmental expression of sulfur compound disproportionation has been placed between 640 and 1050 million years ago (Ma) and linked to increases in atmospheric oxygen. These arguments have their basis in temporal changes in the magnitude of 34S/32S fractionations between sulfate and sulfide. Here, we present a Proterozoic seawater sulfate isotope record that includes the less abundant sulfur isotope 33S. These measurements imply that sulfur compound disproportionation was an active part of the sulfur cycle by 1300 Ma and that progressive Earth surface oxygenation may have characterized the Mesoproterozoic.     

Rapid formation of sulfuric acid particles at near-atmospheric conditions

We investigated the formation of new particles in a laboratory study, starting from H2SO4 produced in situ through the reaction of OH radicals with SO2. Newly formed particles were observed for H2SO4 concentrations above 7 x 10(6) per cubic centimeter. At 293 kelvin, a rough estimate yielded a nucleation rate of 0.3 to 0.4 particles per cubic centimeter per second for approximately 10(7) particles per cubic centimeter of H2SO4 (particle size >/= 3 nanometers). These findings are in agreement with observations from the atmosphere. The results demonstrate that under laboratory conditions similar to the atmosphere, particle formation occurs at atmospheric H2SO4 concentration levels.     

Disulfate ion as an intermediate to sulfuric Acid in Acid rain formation

The oxidation of the bisulfite ion by dissolved oxygen to produce sulfate ion involves the formation of a previously undetected intermediate. This intermediate has a fairly strong Raman band at 1090 wave numbers and a weak Raman band at 740 wave numbers, both of which are probably due to sulfur-oxygen stretches. The intermediate is proposed to be the disulfate ion S(2)O(7)(2-), which hydrolyzes into H(+) and either SO(4)(2-) or HSO(4)(2-) with a half-life of about 52 seconds at 25 degrees C.     

Metastable phases in polar stratospheric aerosols

Phase changes in stratospheric aerosols were studied by cooling a droplet of sulfuric acid (H(2)SO(4)) in the presence of nitric acid (HNO(3)) and water vapor. A sequence of solid phases was observed to form that followed Ostwald's rule for phase nucleation. For stratospheric partial pressures at temperatures between 193 and 195 kelvin, a metastable ternary H(2)SO(4)-HNO(3) hydrate, H(2)SO(4) . HNO(3) . 5H(2)O, formed in coexistence with binary H(2)SO(4) . kH(2)O hydrates (k = 2, 3, and 4) and then transformed to nitric acid dihydrate, HNO(3) . 2H(2)O, within a few hours. Metastable HNO(3) . 2H(2)O always formed before stable nitric acid trihydrate, HNO(3).3H(2)O, under stratospheric conditions and persisted for long periods. The formation of metastable phases provides a mechanism for differential particle growth and sedimentation of HNO(3) from the polar winter stratosphere.     

浓H2SO4和GA3对榛种子萌发的影响

[目的]探讨浓硫酸和GA3浸种及其交互作用对榛种子萌发的影响。[方法]以平榛为试材,将榛种子置于浓硫酸中分别浸种0、10、20和30 min,对酸蚀处理的种子,分别用0、100、300和500 mg/L赤霉素浸种24 h,经与用湿沙自然层积3个月后在恒温箱中催芽。[结果]浓硫酸酸蚀可提高榛种子发芽率,且随着浓硫酸酸蚀时间的延长,榛子的出苗率逐渐升高,但酸蚀时间过长则容易使种胚受伤,影响发芽,以20 min的酸蚀效果较好。GA3能有效打破榛种子休眠,以300 mg/LGA3处理效果较好。浓硫酸和GA3对促进种子萌发有显著的交互作用,以浓硫酸酸蚀20 min和300 mg/L GA3的处理组合对种子发芽率的提高效果最为显著(P<0.05)。[结论]浓硫酸酸蚀榛种子配合赤霉素浸种能够打破榛子的休眠,提高发芽率。