Characteristics of turnover of carbonyl sulfide in four different soils     

Susanne Lehmann  Ralf Conrad 《Journal of Atmospheric Chemistry》1996,23(2):193-207

Release and uptake of carbonyl sulfide (OCS) were measured at 25°C in samples of three forest soils (BL, BW, PBE) and one soil from a rape field (RA). The soil samples were flushed with a constant flow of either air (oxic conditions) or nitrogen (anoxic conditions) containing defined concentrations of OCS. A cryogenic trapping technique with liquid argon (-186 °C) was used to collect gas samples for analysis in a gas chromatograph equipped with a flame-photometric detector. The dependence of net OCS fluxes between soil and atmosphere could be described by a simple model of simultaneous OCS production and OCS uptake. By using this model, production rates (P), uptake rate constants (k) and compensation concentrations (m _c ) of OCS could be determined as function of the soil type and the incubation conditions. Under oxic conditions, OCS production (P) and uptake were observed in all soils tested. However, the compensation concentrations (<166 ng l^-1; 1 ng OCS l^-1=0.41 ppbv) that were calculated from the model were high relative to the ambient OCS concentration (ca. 0.5 ppbv). The production rates (0.16–1.9 ng h^-1 g^-1 dw) that were actually measured when flushing the soil samples with air containing zero OCS were smaller than those (17–114 ng h^-1 g^-1 dw) calculated from the model. This observation was explained by two different concepts: one assuming the existence of a threshold concentration (m _t ) below which OCS was no longer consumed in the soil; the other assuming the existence of two different OCS consumption processes, of which only the process active at elevated OCS concentrations was covered by the experiments. The latter concept allowed the estimation of OCS compensation concentrations that were partially low enough to allow the uptake of atmospheric OCS by soil. Both OCS production and uptake in PBE soil were dependent on soil temperature (optimum 20 °C) indicating a microbial process. However, both production and consumption of OCS were not consistently inhibited by sterilization of the soil, suggesting that they were not exclusively due to microbiological processes. Under anoxic conditions, OCS was also produced, but was not consumed except in one soil (RA). Production of OCS in the soils was stimulated after addition of thiocyanate, but not thiourea, thiosulfate, thioglycolate, tetrathionate, sulfate, elemental sulfur, cysteine and methionine.  相似文献   

梯度法观测大气与森林生态系统间羰基硫(COS)的交换通量   总被引：4，自引：0，他引：4  

徐晓斌  H. G. Bingemer  H.-W. Georgii  G. Gravenhorst  H. Kreilein 《气象学报》1996,54(3):357-364

本工作用梯度法测定了大气与其下垫的森林间ＣＯＳ的交换通量。测量在德国哥廷根大学的一座５０ｍ高的森林观测塔上进行，该塔坐落在德国中部的Ｓｏｌｌｉｎｇ自然保护区的森林中。观测现场生长着树龄分别为１２０ａ和８０ａ的山毛榉和云杉。树冠线约２８ｍ高。在塔上离地面３２ｍ，３８ｍ和５０ｍ的地方用冷以法同时采集了空气样品。样品用气相色谱－火焰光度检测法测定。ＣＯＳ通量由其梯度及扩散系数求出。扩散系数由与ＣＯＳ一起测得的感热和水蒸气通量导出。在稳定边界层条件下共获得２０条廓线。每条廓线都显示ＣＯＳ浓度随高度下降而降低的趋势，说明森林吸收ＣＯＳ。总的结果表明，ＣＯＳ向森林中的平均输送通量为（１４３±５４）ｎｇＣＯＳｍ－２·ｓ－１．  相似文献   

中国大陆邻区的地震活动和中国大陆地震的关系   总被引：1，自引：0，他引：1  

李献智  张国民 《地震》1996,16(3):211-218

研究了３个方面的问题，一是中国大陆周边４个地震带地震活跃期与中国大陆地震活跃期的准同步性和它们目前的活动水平；二是欧亚地震带西部与中国大陆的地震活动呈出现明显的超前或滞后性；三是中国大陆邻区６个地震区的强震与中国大陆活跃期的开始或与中国大陆强震的对应关系。  相似文献   

对加拿大萨德伯里撞击构造的考察及其启示   总被引：1，自引：0，他引：1  

傅昭仁  李紫金 《地质科技情报》1996,15(4):57-63

简介了近年来萨德伯里撞击构造及超大型铜镍硫化物矿床的研究现状和作者现场考察所得的认识。记述了萨德伯里的撞击构造、陨石撞击事件及其构造效应、岩浆杂岩（SIC）和有关成因争论；叙述了该大陨石坑的变形和邻近格林威尔造山作用导致的NW－SE向缩短和剪切作用；还介绍了萨德伯里铜镍硫化物矿床撞击成矿假说；最后，特别提出在从事地球动力学和成矿作用动力学研究时，应十分注意类似萨德伯里陨石撞击灾变事件及损击成矿作用的研究。  相似文献   

陕西小秦岭金矿床中金的赋存状态及分布规律   总被引：2，自引：0，他引：2  

刘埃平  金景福 《矿床地质》1996,15(1):71-79

陕西小秦岭脉状金矿床中，金的赋存状态及其分布与硫化物的发育程度密切相关，金优先赋存于硫化矿物中，只有当硫化物不发育时，才主要以金矿物形式赋存于石英等矿物中。金矿物的Ａｇ／Ａｕ比率主要受成矿温度、硫化物发育程度、成矿热液中Ｃｌ／Ｓ浓度比值等因素制约。  相似文献   

长江中下游地区地下水中Ni元素的背景特征及其形成     

曾昭华 《世界地质》1996,15(4):54-58

根据国家科技攻关研究的结果，论证了长江中下游地区地下水中Ｎｉ元素的背景特征的形成及其分布规律与地下水的含水介质成分，迳流条件以及地下水酸碱度的关系。  相似文献   

秦岭微细浸染型层控锑—金矿床金赋存状态研究   总被引：12，自引：1，他引：12  

张复新 《地质论评》1996,42(6):541-549

对秦岭沉积岩为岩矿岩石的微细浸染型金矿中－高含量金样品的光学，背散射电子－二次离子和高分辨透射电镜图象分析表明，金与砷具有显微尺率的强相关性。矿床中Ａｕ／Ａｓ值是变化的，但在提供分析样品中金和砷是正相关的。  相似文献   

铜镍硫化物矿床成矿作用及成矿模式研究   总被引：10，自引：0，他引：10  

刘月星 《矿产与地质》1997,11(4):225-231

铜镍硫化物矿床是典型的岩浆矿床。其成矿岩体是由上地幔的拉斑玄武岩浆在构造动力驱动下，沿深大断裂侵入形成的含矿铁质超基性岩、铁质基性一超基性杂岩和铁质基性岩体。主矿体通常赋存在这些岩体的中下部、底部或根部。主要成矿作用有岩浆熔离作用（包括岩浆就地熔离作用和岩浆深部熔离作用）和硫化作用。其成矿模式为“以岩浆深部熔离作用为主导的脉动式”成矿，形成由多种矿体（包括岩浆就地熔离型、岩浆深部溶离贯入型、晚期贯入型及交代型和岩浆熔离硫化叠加型）构成的复式矿床。  相似文献   

Emissions of marine biogenic sulfur to the atmosphere of northern Europe   总被引：1，自引：0，他引：1  

Caroline Leck  Henning Rodhe 《Journal of Atmospheric Chemistry》1991,12(1):63-86

Measurements of DMS and other reduced sulfur compounds in surface waters have been carried out from a helicopter in the seas surrounding Scandinavia. Average summer time concentrations of DMS ranged from 70 to 150 ngS L^-1. Simultaneous measurements of biological and physical parameters revealed no correlation between DMS and phytoplankton species, species assemblages, total phytoplankton biomass, chlorophyll a, temperature, and salinity. The only exception was a correlation between DMS concentration, Chrysochromulina spp. belonging to the Prymnesiophyceae, and salinity over a narrow range of salinity in the Baltic Sea.The flux of reduced sulfur to the atmosphere in July in this region is estimated to be 120–170 gS m^-2 d^-1 from the Baltic, 240–810 in the Kattegat/Skagerrak, and 120–690 in the North Sea. Annual fluxes are roughly 100 times higher than these daily fluxes. On an annual basis, biogenic sulfur emissions from the coastal seas are negligible (<1%) compared to the anthropogenic emissions in northern Europe. However, during the summer months, the biogenic sulfur emissions from the seas surrounding the Scandinavian peninsula are estimated to be as high as 20–70% of the anthropogenic emissions in Scandinavia. This makes it of interest to incorporate the biogenic emissions in calculations of long-range transport and deposition of sulfur within the region.Other volatile sulfur species, mainly methyl mercaptan, contribute about 10% of the total flux of reduced sulfur. Estimated fluxes of CS₂ to the atmosphere ranged from 1 gS m^-2 d^-1 in the Baltic Sea to 6 gS m^-2 d^-1 in the North Sea. No emissions for H₂S or COS were detected.  相似文献   

金在硫化物矿物中呈负价态存在及其形成机理初探   总被引：13，自引：1，他引：12  

李九玲  冯大明 《地质学报》1995,69(1):67-77,T001

通过对中国广西卡林型金矿的含金毒沙、黄铁矿及用热液实验方法合成的含黄铁矿、白铁矿的分析和研究,特别是光电子能谱分析,发现其中存在电子结合能低于自然金（Ａｕ＾０）的“不可见金”。因而提出金在上述硫化物矿物中由于取代部分硫并与硫呈共价键结合而负价态点。本文料从金的化学及地球化学性质,毒砂,黄铁矿及白铁矿的晶体化学特征和产出的地球化学环境等三方面初步探讨了其形成的可能性。  相似文献