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91.
Due to acidity and metals from acid sulfate soils (a.s. soils), many watercourses in midwestern Finland have since 1960s regularly experienced short but intensive periods of poor water quality during high water flow. This has led to occasional massive fish kills and a significant decline in fish populations. 相似文献
92.
Ambient concentrations of sulfur dioxide (SO2), nitrogen dioxide (NO2), and ozone (O3) were measured at 51 sampling points by passive sampling technique in Kocaeli, an important industrial city in Turkey. Samples were analyzed by UV‐spectrophotometry for NO2 and O3 and by ion chromatography for SO2, respectively. Concentrations of SO2, NO2, and O3 were determined to investigate their spatial distribution and source characterization. The sampling campaigns revealed an average concentration of 8 µg/m3 (max. 82 µg/m3) for SO2, and 14 µg/m3 (max. 40 µg/m3) for NO2, in summer; while average winter concentrations were 25 µg/m3 (max. 61 µg/m3) for SO2, and 50 µg/m3 (max. 100 µg/m3) for NO2. The maximum ozone concentrations were determined to be 86 µg/m3 in summer and 61 µg/m3 in winter downwind of the source areas of the precursor pollutant emissions. The results showed that NO2 and SO2 concentrations in industrial and urban areas were two to four times higher compared with rural areas in the summer and winter. In the light of the information obtained from the spatial interpolation of the pollutant concentrations, a selection of appropriate locations for continuous monitoring was suggested according to the European Community (EU) directives. 相似文献
93.
Yu Chen Yan‐peng Mao Hai‐song Zhu Jing‐yi Cheng Xiang‐li Long Wei‐kang Yuan 《洁净——土壤、空气、水》2010,38(7):601-607
The wet ammonia (NH3) desulfurization process can be retrofitted to remove nitric oxide (NO) and sulfur dioxide (SO2) simultaneously by adding soluble cobalt(II) salt into the aqueous ammonia solution. Activated carbon is used as a catalyst to regenerate hexaminecobalt(II), Co(NH3), so that NO removal efficiency can be maintained at a high level for a long time. In this study, the catalytic performance of pitch‐based spherical activated carbon (PBSAC) in the simultaneous removal of NO and SO2 with this wet ammonia scrubbing process has been studied systematically. Experiments have been performed in a batch stirred cell to test the catalytic characteristics of PBSAC in the catalytic reduction of hexaminecobalt(III), Co(NH3). The experimental results show that PBSAC is a much better catalyst in the catalytic reduction of Co(NH3) than palm shell activated carbon (PSAC). The Co(NH3) reduction reaction rate increases with PBSAC when the PBSAC dose is below 7.5 g/L. The Co(NH3) reduction rate increases with its initial concentration. Best Co(NH3) conversion is gained at a pH range of 2.0–6.0. A high temperature is favorable to such reaction. The intrinsic activation energy of 51.00 kJ/mol for the Co(NH3) reduction catalyzed by PBSAC has been obtained. The experiments manifest that the simultaneous elimination of NO and SO2 by the hexaminecobalt solution coupled with catalytic regeneration of hexaminecobalt(II) can maintain a NO removal efficiency of 90% for a long time. 相似文献
94.
Bilge Özbay 《洁净——土壤、空气、水》2012,40(6):571-577
Air quality has been deteriorated seriously in urban areas as a result of increasing anthropogenic activities. Meteorological conditions affect air pollution levels in the urban atmosphere significantly due to their important role in transport and dilution of the pollutants. This paper aims to investigate usability of some promising statistical methods for examining the impacts of metrological factors on SO2 and PM10 levels. Data were collected from city centre of Kocaeli in winter periods from 2007 to 2010 as pollutant concentrations increase in winters due to expanding combustion facilities. Results of bivariate correlation analysis showed that humidity and rainfall have remarkable negative correlations with the pollutants. Multiple linear regression models and artificial neural network (ANN) models were used to predict next day's PM10 and SO2 levels. In regression models calculated R2 values were 0.89 and 0.75 for PM10 and SO2, respectively. Among the various architectures, single layer networks provided better performance in ANN applications. Highest R2 values were obtained as 0.89 and 0.69 for PM10 and SO2, respectively, by using appropriate networks. 相似文献
95.
Punit Kumar Mudgal Anil Kumar Sharma C. D. Mishra S. P. Bansal K. S. Gupta 《Journal of Atmospheric Chemistry》2008,61(1):31-55
This is the first study, which shows both NH3 and NH4+ to inhibit the autoxidation of aqueous SO2 in the pH range 7.0–8.5. The rate of the autoxidation, R
aut
, in both buffered and unbuffered media at a fixed pH is in conformity with the rate law:
where R
0
is rate in the absence of the inhibitors, B is a pH dependent empirical constant and [Inh]T is the analytical concentration of NH3 or NH4+. Both ammonia and ammonium ions appear to inhibit the autoxidation either by scavenging SO4− radicals or by forming less-reactive /unreactive Co(II)-NH3 complexes or both. The atmospheric relevance of the inhibition by ammonia and ammonium ions is discussed. 相似文献
96.
Sarah-Jane Barnes Dany Savard L. Paul Bédard Wolfgang D. Maier 《Mineralium Deposita》2009,44(6):647-663
We have determined the S, Se, Cu and La contents through a complete stratigraphic section of the Bushveld Complex. The principle
aim was to determine which phases controlled these elements. S, Se and Cu show positive correlations, but these elements do
not correlate with La. In most cases, the concentration of S, Se and Cu in rocks containing greater than 800 ppm S can be
modeled by segregation of a Fe–Ni–Cu sulfide liquid from a fractionating magma. As the magma evolved, Se and Cu were depleted
by the continual segregation of sulfide liquid and the S/Se and S/Cu of the rocks increased. The Se/Cu ratio is higher in
the more evolved rocks, which suggests that Se has a slightly lower partition coefficient than Cu into sulfide liquid (1,200
versus 1,700). The Lower and lower Critical Zone of the complex contains on average only 99 ppm S. The low S content of these
rocks has led some authors to suggest that these rocks do not contain cumulate sulfides, despite the fact that they are moderately
enriched in PGE. These samples fall along the same trend as the S-rich samples on the S-versus-Se plot and the S/La and Se/La
ratios are greater than the initial magmas suggesting that despite the low S contents cumulate sulfides are present. Three
models may be suggested in order to explain the low S content in the Lower and Critical Zone rocks: (a) the sulfides that
were present have migrated away from the cumulate pile into the footwall or center of the intrusion; (b) the magma was saturated
in sulfides at depth and during transport some sulfides lagged in embayments; (c) the rocks have lost both S and Se at high
temperature. The first two models have important implications for exploration. 相似文献
97.
We have investigated melting relations in the Fe–O–S ternary system in the pressure range of 15–27 GPa and 1873 K. Subsolidus
phase relations are Fe, Fe3S2, and FeO up to 17 GPa and Fe, Fe3S, and FeO above this pressure. The eutectic temperature slightly decreases from ambient pressure to 17 GPa, whereas increases
above this pressure. The eutectic temperature in this study is 100 K lower than that in the Fe–S binary system. The oxygen
content in the Fe–O–S eutectic liquid drops when the coexisting solid phases changes from FeS to Fe3S2. The cotectic lines in the ternary phase diagram lie close to the Fe–FeS binary axis. The isothermal sections indicate that
oxygen solubility in the Fe–O–S liquid increases with increasing temperature, and with increasing sulfur content. The solubility
of sulfur in the solid Fe has a maximum value at the eutectic temperature, and decreases with increasing temperature. Our
results could have important implications for formation and composition of the Martian core. 相似文献
98.
The Chadormalu is one of the largest known iron deposits in the Bafq metallogenic province in the Kashmar-Kerman belt, Central Iran. The deposit is hosted in Precambrian-Cambrian igneous rocks, represented by rhyolite, rhyodacite, granite, diorite, and diabasic dikes, as well as metamorphic rocks consisting of various schists. The host rocks experienced Na (albite), calcic (actinolite), and potassic (K-feldspar and biotite) hydrothermal alteration associated with the formation of magnetite–(apatite) bodies, which are characteristic of iron oxide copper-gold (IOCG) and iron oxide-apatite (IOA) systems. Iron ores, occurring as massive-type and vein-type bodies, consist of three main generations of magnetite, including primary, secondary, and recrystallized, which are chemically different. Apatite occurs as scattered irregular veinlets in various parts of the main massive ore-body, as well as apatite-magnetite veins and disseminated apatite grains in marginal parts of the deposit and in the immediate wall rocks. Minor pyrite occurs as a late phase in the iron ores. Chemical composition of magnetite is representative of an IOA or Kiruna-type deposit, which is consistent with other evidence.Whole rock geochemical data from various host rocks confirm the occurrence of Na, Ca, and K alteration consistent with the formation of albite, actinolite, and K-feldspar, respectively. The geochemical investigation also includes the nature of calc-alkaline igneous rocks, and helps elaborating on the spatial and temporal association, and possible contribution of mafic to felsic magmas to the evolution of ore-bearing hydrothermal fluids.Fluid inclusion studies on apatites from massive- and vein-type ores show a range of homogenization temperatures from 266 to 580 °C and 208–406 °C, and salinities from 0.5 to 10.7 wt.% and 0.3–24.4 wt.% NaCl equiv., respectively. The fluid inclusion data suggest the involvement of evolving fluids, from low salinity-high temperature, to high salinity-low temperature, in the formation of the massive- and vein-type ores, respectively. The δ34S values obtained for pyrite from various parts of the deposit range between +8.9 and +14.4‰ for massive ore and +18.7 to +21.5‰ for vein-type ore. A possible source of sulfur for the 34S-enriched pyrite would be originated from late Precambrian-early Cambrian marine sulfate, or fluids equilibrated with evaporitic sulfates.Field observations, ore mineral and alteration assemblages, coupled with lithogeochemical, fluid inclusion, and sulfur isotopic data suggest that an evolving fluid from magmatic dominated to surficial brine-rich fluid has contributed to the formation of the Chadormalu deposit. In the first stages of mineralization, magmatic derived fluids had a dominant role in the formation of the massive-type ores, whereas a later brine with higher δ34S contributed to the formation of the vein-type ores. 相似文献
99.
The Milin Kamak gold-silver deposit is located in Western Srednogorie zone, 50 km west of Sofia, Bulgaria. This zone belongs to the Late Cretaceous Apuseni-Banat-Timok-Srednogorie magmatic and metallogenic belt. The deposit is hosted by altered trachybasalt to andesitic trachybasalt volcanic and volcanoclastic rocks with Upper Cretaceous age, which are considered to be products of the Breznik paleovolcano. Milin Kamak is the first gold-silver intermediate sulfidation type epithermal deposit recognized in Srednogorie zone in Bulgaria. It consists of eight ore zones with lengths ranging from 400 to 1000 m, widths from several cm to 3–4 m, rarely to 10–15 m, an average of 80–90 m depth (a maximum of 200 m) and dip steeply to the south. The average content of gold is 5.04 g/t and silver – 13.01 g/t. The styles of alteration are propylitic, sericite, argillic, and advanced argillic. Ore mineralization consists of three stages. Quartz-pyrite stage I is dominated by quartz, euhedral to subhedral pyrite, trace pyrrhotite and hematite in the upper levels of the deposit. Quartz-polymetallic stage II is represented by major anhedral pyrite, galena, Fe-poor sphalerite; minor chalcopyrite, tennantite, bournonite, tellurides and electrum; and trace pyrrhotite, arsenopyrite, marcasite. Gangue minerals are quartz and carbonates. The carbonate-gold stage III is defined by deposition of carbonate minerals and barite with native gold and stibnite.Fluid inclusions in quartz are liquid H2O-rich with homogenization temperature (Th) ranging from 238 to 345 °C as the majority of the measurements are in the range 238–273 °C. Ice-melting temperatures (Tm) range from −2.2 to −4.1 °C, salinity – from 3.7 to 6.6 wt.% NaCl equiv. These measurements imply an epithermal environment and low- to moderate salinity of the ore-forming fluids.δ34S values of pyrite range from −0.49 to +2.44‰. The average calculated δ34S values are 1.35‰. The total range of δ34S values for pyrite are close to zero suggesting a magmatic source for the sulfur. 相似文献
100.
《Chemie der Erde / Geochemistry》2017,77(1):147-157
The study was carried out on the Sulejów dam reservoir (Central Poland). Water and sediment samples were collected between February and October 2006. Sulfur compounds in the sediment were chemically extracted and subjected to isotopic analysis.Large variability of SO42− concentration in the water column (from 10.3 to 36.2 mg/dm3) and the isotopic composition of sulfur (δ34S from 2.1 to 5.4‰) was observed. The main identified sources of SO42− were watercourses, surface runoff, and phosphorus fertilizers.Both oxidized sulfur species (SO42−) and its reduced forms were found in sediments. Particular sulfur forms were characterized by large variations in both, concentrations and the isotopic composition of sulfur. SO42− in the sediment and in the water column had different genesis. Bacterial oxidation of organic sulfur and its binding in SO42− were observed in the sediment. Under reducing conditions, oxidized and organic sulfur is converted to H2S which reacted with Fe or other metallic ions leading to metal sulfide precipitation. Monosulfides were shown to have a very low concentration, ranging up to 0.07 mg/g of sediment. The transformation of elemental sulfur from sulfides through their chemical oxidation occurred in the sediment. 相似文献