In situ measurements of hydrogen sulfide, oxygen, and temperature in diffuse fluids of the ultramafic-hosted Logatchev hydrothermal vent field (Mid-Atlantic Ridge)

The Logatchev hydrothermal vent field (14°45'N, Mid-Atlantic Ridge) is located in a ridge segment characterized by mantle-derived ultramafic outcrops. Compared to basalt-hosted vents, Logatchev high temperature fluids are relatively low in sulfide indicating that the diffuse, low temperature fluids of this vent field may not contain sufficient sulfide concentrations to support a chemosymbiotic invertebrate community. However, the high abundances of bathymodiolin mussels with bacterial symbionts related to free-living sulfur oxidizing bacteria suggested that bioavailable sulfide is present at Logatchev. To clarify if diffuse fluids above mussel beds of Bathymodiolus puteoserpentis provide the reductants and oxidants needed by their symbionts for aerobic sulfide oxidation, in situ microsensor measurements of dissolved hydrogen sulfide and oxygen were combined with simultaneous temperature measurements. High temporal fluctuations of all three parameters were measured above the mussel beds. H2S and O2 co-existed with mean concentrations between 9-31 µM (H2S) and 216-228 µM (O2). Temperature maxima (<= 7.4°C) were generally concurrent with H2S maxima (<= 156 µM) and O2 minima (>= 142 µM). Long-term measurements for 250 days using temperature as a proxy for oxygen and sulfide concentrations indicated that the mussels were neither oxygen- nor sulfide-limited. Our in situ measurements at Logatchev indicate that sulfide may also be bioavailable in diffuse fluids from other ultramafic-hosted vents along slow- and ultraslow-spreading ridges.

Hydrogen sulfide health effects and recommended air quality standard : prepared for the Illinois Institute for Environmental Quality /

Includes bibliographical references.

Can hydrogen sulfide prevent preeclampsia and fetal growth restriction?

The exact aetiology of preeclampsia is unknown, but there is a good association with an imbalance in angiogenic growth factors and abnormal placentation [1]. Hydrogen sulphide (H2S), a gaseous messenger produced mainly by cystathionine γ-lyase (CSE), is pro-angiogenic vasodilator [2] and [3]. We hypothesized that a reduction in CSE activity may alter the angiogenic balance in pregnancy and induce abnormal placentation and maternal hypertension. Plasma levels of H2S were significantly decreased in preeclamptic women (p < 0.01), which was associated with reduced CSE message and protein expression in human placenta as determined by real-time PCR and immunohistochemistry. Inhibition of CSE activity by DL-propargylglycine (PAG) in first trimester (8–12 weeks gestation) human placental explants had reduced placenta growth factor (PlGF) production as assessed by ELISA and inhibited trophoblast invasion in vitro. Endothelial CSE knockdown by siRNA transfection increased the endogenous release of soluble fms-Like tyrosine kinase-1 (sFlt-1) and soluble endoglin, (sEng) from human umbilical vein endothelial cells while adenoviral-mediated CSE overexpression inhibited their release. Administration of PAG to pregnant mice induced hypertension, liver damage, and promoted abnormal labyrinth vascularisation in the placenta and decreased fetal growth. Finally, a slow releasing, H2S-generating compound, GYY4137, inhibited circulating sFlt-1 and sEng levels and restored fetal growth that was compromised by PAG-treatment demonstrating that the effect of CSE inhibitor was due to inhibition of H2S production. These results imply that endogenous H2S is required for healthy placental vasculature and a decrease in of CSE/H2S activity may contribute to the pathogenesis of preeclampsia. References [1] S. Ahmad, A. Ahmed, Elevated placental soluble vascular endothelial growth factor receptor-1 inhibits angiogenesis in preeclampsia, Circ Res., 95 (2004), pp. 884–891. [2] G. Yang, et al., H2S as a physiologic vasorelaxant: hypertension in mice with deletion of cystathionine gamma-lyase, Science, 322 (2008), pp. 587–590. [3] A. Papapetropoulos, et al., Hydrogen sulfide is an endogenous stimulator of angiogenesis, Proc Natl Acad Sci USA, 106 (2009), pp. 21972–21977.

Development and testing of an evaluation procedure for commercial manure additive products.

Manure additive products can be used to reduce odour emissions (OE) from livestock farms. The standardised evaluation of these manure additive products under specific farm conditions is important. In this study, the efficacy of a manure additive (WonderTreat(TM), CKLS, Inc., Hong-Kong) was assessed under Australian conditions utilising a combination of laboratory and field-scale evaluation techniques. As a first step, the efficacy of the manure additive was assessed in a laboratory-scale trial using a series of uniformly managed digesters and standard odour, liquor ammonia and hydrogen sulphide concentration measurement procedures. This showed that the addition of WonderTreat(TM) at the 'low dose rate' (LDR) (102.6 g m-2) used during the trial significantly, but only marginally (30%; P = 0.02) reduced the OE rate (mean 13.9 OU m-2 s-1) of anaerobic pig liquor relative to an untreated control (UC) (19.9 OU m-2 s-1). However, the 'high dose rate' (HDR) (205.3 g m-2) also assessed during the trial preformed similarly (19.7 OU m-2 s-1) to the UC. No statistically significant difference in the concentrations of a range of measured water quality variables at the 5% level was observed between the treatments or controls digesters. As a second step, a field-scale assessment of the manure additive was undertaken at a commercial piggery. Two piggery manure lagoons (each with approximately 2500 m2 surface area) were included in the study; one was treated with WonderTreat(TM) while the other was used as control. The efficacy of the treatment was assessed using olfactometric evaluation of odour samples collected from the surface of the pond using a dynamic wind tunnel and ancillary equipment. No statistically significant reduction in OE rate could be demonstrated (P = 0.35), partially due to the limited number of samples taken during the assessment. However, there was a numerical reduction in the average OE rate of the treatment pond (29 OU m-2 s-1 at 1 m s-1) compared to the control lagoon (38 OU m-2 s-1 at 1 m s-1).

Investigations on the preparation, oxidation and reduction reactions of thiophosphoryl fluoride

Pure thiophosphoryl fluoride has been prepared by the fluorination of thiophosphoryl chloride by sodium fluoride in acetonitrile medium. Oxidation of this phosphoryl fluoride by acidified chloramine-T ruptures the phosphorus-sulphur bond and oxidises the sulphur present to the hexavalent state. Anhydrous hydrogen iodide reduces the sulphur to hydrogen sulphide and phosphorus to the trivalent state.

Hydrolytic reactions of tetrasulphur tetranitride in a homogeneous medium

The hydrolytic reactions of tetrasulphur tetranitride are studied in a homogeneous medium. Alkaline hydrolysis gives sulphite, thiosulphate, sulphate and sulphide whereas the products in acid hydrolysis are mainly sulphur dioxide, elemental sulphur and hydrogen sulphide, with traces of polythionates. Under optimum conditions, tetrasulphur tetranitride reacts with sulphite consuming 2 moles of sulphite per mole of sulphur nitride to give 2 moles of trithionate. The reaction of sulphur nitride with thiosulphuric acid gives pentathionate and tetrathionate.

Hydrolytic reactions of esters and amides of thiosulphurous acid in a homogeneous medium

The hydrolytic reactions of esters and amides of thiosulphurous acid are investigated in a homogeneous medium. The esters are hydrolysed by alkali to give sulphide, sulphite and thiosulphate whereas the amides are resistant towards alkali. Both the esters and amides are hydrolysed by acids giving hydrogen sulphide, sulphur dioxide, polythionates and elemental sulphur. The hydrolysis of these esters and amides in presence of sulphurous acid and thiosulphuric acid gives tetrathionate and hexathionate, respectively.

Molekyylibiologisten menetelmien kehittäminen ihmisen suoliston sulfaattia pelkistävien bakteerien määrittämiseksi

Ihmisen ruuansulatuskanavan bakteeriston kehitys alkaa syntymästä, jolloin ensimmäiset bakteerit kansoittavat steriilin ruuansulatuskanavan. Bakteeristo kehittyy perimän, ympäristön ja varhaisen ruokavalion vaikutuksesta kohti monimuotoisempaa bakteeripopulaatiota. Aikuisen ruuansulatuskanavan normaalibakteeristo on varsin muuttumaton, mutta siihen vaikuttavat monet tekijät, kuten ikä, terveydentila, ruokavalio ja antibioottien käyttö. Bakteeriston koostumus vaihtelee ruuansulatuskanavan eri osissa ja bakteerimäärä kasvaa kohti paksusuolta, ollen paksusuolessa ja ulosteessa peräti 1010-1012 pmy/ml. Suurin osa ruuansulatuskanavan bakteereista on anaerobeja. Ruuansulatuskanavan bakteeristo vaikuttaa muun muassa suoliston kehittymiseen ja hiilihydraattien ja proteiinien hajotukseen sekä toimii osana immuunipuolustusta. Sulfaattia pelkistävät bakteerit (SRB) ovat monimuotoinen ryhmä pääosin anaerobisia bakteereita, jotka käyttävät aineenvaihdunnassaan elektronin vastaanottajana sulfaattia muuttaen sen lopulta sulfidiksi. SRB:t ovat sopeutuneet useisiin erilaisiin ympäristöihin. Niitä tavataan mm. vesistöjen sedimenteissä sekä ihmisen ruuansulatuskanavassa. Ihmisen ruuansulatuskanavassa on SRB:ta n. 105-108 pmy/g, ja niitä on löydetty erityisesti anaerobisista osista kuten suun ientaskuista ja paksusuolesta. SRB:t voivat olla haitaksi ruuansulatuskanavalle tuottamansa sulfidin vuoksi, joka esiintyy vesiliuoksessa vetysulfidina. Tämän on havaittu olevan toksista suoliston epiteelisoluille. Viimeaikoina on kiinnostuttu sulfaatinpelkistäjien yhteydestä suoliston sairaustiloihin, kuten tulehduksellisiin suolistosairauksiin (IBD). Pro gradu -tutkimukseni tavoitteena oli kehittää PCR-DGGE- ja qPCR-menetelmät ulosteen sulfaattia pelkistävien bakteerien määritykseen. Kohdegeeninä menetelmänkehityksessä käytettiin dsrAB-geeniä, joka koodaa dissimilatorista sulfiitinpelkistysentsyymiä. dsrAB-geeni on sulfaatinpelkistäjille ominainen konservoitunut geenialue, johon perustuvia tutkimuksia ei vielä ole paljon ihmispuolelta. qPCR-menetelmä saatiin optimoitua herkäksi ja spesifiseksi käyttäen dsrA-geenispesifisiä alukkeita, mutta PCR-DGGE-menetelmää ei saatu optimoitua käytössä olleilla alukkeilla, jotka monistivat PCR-DGGE:ssa myös negatiivikontrollikantoja. Tutkittaessa qPCR:lla IBD:tä (Crohn ja ulseratiivinen koliitti) sairastavien lasten ja terveiden kontrollihenkilöiden ulostenäytteistä eristettyä DNA:ta, merkittävää eroa SRB-määrissä ei havaittu eri ryhmien välillä. Crohnin tautia sairastavien aktiivisen vaiheen ja oireettoman vaiheen näytteiden välillä oli kuitenkin tilastollisesti merkitsevä ero (SRB-määrät; oireeton vaihe>oireellinen vaihe) (P <0,05).

Porous wide band gap BiNbO4 ceramic nanopowder synthesised by low temperature solution-based method for gas sensing applications

In this study, we report the gas sensing behavior of BiNbO4 nanopowder prepared by a low temperature simple solution-based method. Before the sensing behaviour study, the as-synthesized nanopowder was characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, UV-diffuse reflectance spectroscopy, impedance analysis, and surface area measurement. The NH3 sensing behavior of BiNbO4 was then studied by temperature modulation (50-350 degrees C) as well as concentration modulation (20-140 ppm). At the optimum operating temperature of 325 degrees C, the sensitivity was measured to be 90%. The cross-sensitivity of as-synthesized BiNbO4 sensor was also investigated by assessing the sensing behavior toward other gases such as hydrogen sulphide (H2S), ethanol (C2H5OH), and liquid petroleum gas (LPG). Finally, selectivity of the sensing material toward NH3 was characterized by observing the sensor response with gas concentrations in the range 20-140 ppm. The response and recovery time for NH3 sensing at 120 ppm were about 16 s and about 17 s, respectively.

Water-responsive carbon nanotubes for selective detection of toxic gases

Ammonia plays an important role in our daily lives and hence its quantitative and qualitative sensing has become necessary. Bulk structure of carbon nanotubes (CNTs) has been employed to detect the gas concentration of 10 ppm. Hydrophobic CNTs were turned to hydrophilic via the application of a ramp electric field that allowed confinement of a controlled amount of water inside CNT microstructure. These samples were then also used to detect different gases. A comparative study has been performed for sensing three reducing gases, namely, ammonia, sulphur-di-oxide, and hydrogen sulphide to elaborate the selectivity of the sensor. A considerable structural bending in the bulk CNT was observed on evaporation of the confined water, which can be accounted to the zipping of individual nanotubes. However, the rate of the stress induced on these bulk microstructures increased on the exposure of ammonia due to the change in the surface tension of the confined solvent. A prototype of an alarm system has been developed to illustrate sensing concept, wherein the generated stress in the bulk CNT induces a reversible loss in electrical contact that changes the equivalent resistance of the electrical circuit upon exposure to the gas. (C) 2015 AIP Publishing LLC.

Estrategias de arranque de biofiltros orgánicos para el tratamiento de corrientes gaseosas contaminadas con compuestos de azufre

[ES]El disulfuro de carbono (CS2) y el sulfuro de hidrógeno (H2S) son gases especialmente tóxicos presentes en una gran cantidad de emisiones gaseosas industriales, principalmente en la producción de fibras de rayón a partir de celulosa en el caso del CS2, y en la industria petroquímica en el caso del H2S. La legislación vigente en cuanto a las emisiones de estos compuestos se refiere hace que su tratamiento sea, en muchos casos, necesario. La biofiltración como tecnología para el tratamiento de corrientes gaseosas contaminadas se ha convertido en los últimos años en una alternativa a los tratamientos físico-químicos empleados hasta la fecha. Sin embargo, uno de los principales obstáculos a la hora de la implantación de este tratamiento biológico a escala industrial es la duración del periodo de aclimatación de la biomasa encargada de degradar los contaminantes, que en función del compuesto a tratar puede resultar demasiado largo para la aplicación comercial de esta tecnología. El presente trabajo se centra en el estudio de estos periodos de arranque y aclimatación, especialmente lentos en el caso del CS2, y propone una estrategia de arranque basada en la reutilización de biomasa capaz de degradar los compuestos de interés, almacenada tras usos anteriores, que permite reducir el tiempo necesario para alcanzar eficacias de eliminación elevadas. Paralelamente, se ha concluido que paradas de corta duración no afectan de manera importante a la operación del sistema.

Produção biogênica de sulfetos em amostras de água e óleo

Durante a exploração de petróleo offshore (fora da costa), a injeção de água do mar no processo de recuperação secundária de petróleo, ocasiona a produção de sulfeto de hidrogênio (H2S) pela presença das bactérias redutoras de sulfato (BRS), que reduzem o sulfato presente na água em sulfeto. A produção intensiva de H2S tem sido um dos maiores problemas das indústrias petrolíferas, pois constitui-se uma das principais causas de corrosão em linhas de produção (tubulações), equipamentos e tanques metálicos. Os principais micro-organismos presentes em amostras salinas provenientes de tanques de armazenamento de água e óleo da indústria do petróleo são as bactérias anaeróbias heterotróficas totais (BANHT) e as bactérias redutoras de sulfato (BRS). Atualmente, a quantificação desses grupos microbianos é realizada através da técnica do Número Mais Provável (NMP) que estima o resultado em aproximadamente 28 dias. Neste trabalho foi utilizada a metodologia de produção semi-contínua de sulfetos biogênicos por 15 dias, numa tentativa de correlacionar com os resultados de quantificação de BANHT e BRS através da técnica convencional do NMP. Nesse caso, avaliou-se as condições mais adequadas para a produção biogênica de sulfetos em tanques, alterando-se parâmetros tais como salinidade, temperatura e composição do meio de cultura. Verificou-se que os aumentos da salinidade e da temperatura do meio implicaram na diminuição da atividade biogênica semi-contínua de geração de sulfetos. E conforme dilui-se o meio de cultura, o crescimento de bactérias foi reduzido, assim como a geração de sulfetos. A quantificação de BRS e BANHT foi avaliada pela técnica do NMP de acordo com o método do FDA em 2011 e de Harrigan em 1998. Este último subestima a população microbiana, desconsiderando os limites e erros provenientes da técnica

Reutilización de escoria negra de acería como soporte en biofiltros para la eliminación de H2S del biogás.

[EN]Due to the limitations associated with fossil fuels it is necessary to promote energy sources that are renewable as well as eco-friendly, such as biogas generated in anaerobic digesters. The biogas, composed principally of methane and CO2, is the result of the biodegradation of organic matter under anaerobic conditions. Its use as fuel is limited by the presence of minority compounds such as hydrogen sulphide (H2S); therefore, its pre-treatment is necessary. Currently there are various technologies for the removal of H2S from a gas stream, but most of them are based on physic-chemical treatments which have a number of drawbacks as reactive consumption, generation of secondary flows, etc. Biofiltration has been used as an efficient and low cost alternative to conventional purification processes, and excellent results for the degradation of H2S have been obtained. However process can be limited due to the progressive ageing of the support material, along with the loss of nutrients and other specific characteristics necessary for the good development of biomass. The purpose of this project is to develop a mixed support consisting of a mixture of an organic material and an inorganic support for its application in the removal of the H2S from biogas. This support material helps to optimize the characteristics of the bed and extend its lifespan. The development of such material will contribute to the implementation of biofiltration for treating biogas from anaerobic digesters for its use as biofuel. The inorganic material used is electric arc furnace (EAF) black slag, a by-product generated in large quantities in the production of steel in the Basque Country. Although traditionally the slag has been used in civil engineering, its physicochemical characteristics make it suitable for reuse as a filter medium in biofiltration. The main conclusion drawn from the experimental results is that EAF black slag is a suitable co-packing material in organic biofilters treating H2S-polluted gaseous streams. High pollutant removal rates have been achieved during the whole experimental period. The removal capacity recorded in biofilters with less inorganic material was higher than in those with higher slag portion. Nevertheless, all the biofilters have shown a satisfactory response even at high inlet loads (48 g·m-3·h-1), where the RE has not decreased over 82%.

Biofiltração de compostos orgânicos voláteis e gás sulfídrico em estações de despejos industriais de processamento de hidrocarbonetos.

Neste trabalho foi estudado o tratamento simultâneo por biofiltração de emissões de compostos orgânicos voláteis, COV e gás sulfídrico, H2S, em estações de tratamento de despejos industriais, de refinaria de petróleo, ETDI. A biofiltração dos gases emanados da EDTI mostrou ser uma técnica de alta eficiência, atingindo valores de 95 a 99 % para tratamento simultâneo de COV e H2S em concentrações de 1000 e 100 ppmv, respectivamente. Foram realizados testes em 95 dias consecutivos de operação, em uma planta piloto instalada na Superintendência da Industrialização do Xisto, SIX, em São Mateus do Sul, Paraná, de março a agosto de 2006. O biofiltro foi do tipo fluxo ascendente, com 3,77 m3 de leito orgânico, composto de turfa, carvão ativado, lascas de madeira, serragem brita fina além de outros componentes menores. Foi realizada inoculação biológica com lodo filtrado de estação de tratamento de esgoto sanitário. As vazões de gás aplicadas variaram de 85 a 407 m3/h, resultando em taxas de carga de massa de 11,86 a 193,03 g de COV/h.m3 de leito e tempos de residência de 24 segundos a 6,5 minutos, com tempo ótimo de 1,6 minutos. A capacidade máxima de remoção do sistema encontrada, nas condições testadas, foi de 15 g de COV/h. m3, compatível com os valores encontrados na literatura para depuração biológica de COV na escala praticada. Também foi verificada a redução de componentes específicos de BTX, demonstrando boa degradabilidade dos compostos orgânicos. Finalmente o biofiltro demonstrou boa robustez biológica diante dos desvios operacionais intencionalmente provocados, tais como falta de umidade do leito, baixa temperatura, alta vazão, falta de carga de COV e baixo pH do leito. Depois de retomada a condição de operação estável, a biofiltração rapidamente atingiu o estado de equilíbrio, assegurando o uso eficiente e confiável da técnica no tratamento de gases de EDTI na indústria do hidrocarbonetos ou em refinarias de petróleo.

Fish and shell fish fauna of the retting and nonretting zones of the Kadinamkulam kayal, Kerala

Retting of coconut husk is one of the major problems of pollution in the estuaries (kayals) of Kerala. Retting activity has resulted in the mass destruction of the flora and fauna and has converted sizeable sections of the kayal into virtual cesspools of foul smelling stagnant waters. Levels of hydrogen sulphide, phosphate and BOD, increased while dissolved oxygen and fish and shellfish fauna decreased in the ambient waters. In the Kadinamkulam kayal a total of 37 species of fishes belonging to 26 families, 5 species of prawn and 2 species each of crabs and molluscs were recorded from the no retting zone, whereas only 20 species of fish in dead condition were collected from the rating zone. Prawns, crabs and molluscs were absent at the vetting zone. Majority of the fish fauna in the kayal were marine forms.