松辽盆地南部浅层天然气地球化学特征及其成因分析

由于松辽盆地南部浅层天然气成因研究比较薄弱,通过采集伏龙泉地区泉头组天然气样品,对天然气组分、碳同位素、轻烃组分进行了分析。结果表明该地区天然气有油型气和生物降解气2种成因。第一类天然气甲烷碳同位素值在-35‰左右,甲烷及其同系物碳同位素呈正碳分布;甲基环己烷指数在20%左右、环己烷指数略高于10%,符合油型气的特征。由甲烷碳同位素计算的R₀值,以及轻烃中的庚烷值和异庚烷值均在高-过成熟的范围,因此是高成熟的油型气。第二类天然气甲烷碳同位素偏轻,丙烷碳同位素偏重;轻烃色谱图中以环烷烃为主峰,轻烃内组成中支链烷烃和环烷烃含量高,各项轻烃参数(甲基环己烷指数、庚烷值、K1值等)都在较大范围内波动,为生物降解气。这一研究对于今后该区天然气勘探与资源评价及其成藏机理研究具有重要意义。     

青藏高原乌丽冻土区二氧化碳成因探讨

为了查明青藏高原乌丽冻土区天然气的组分与成因,对采集自乌丽水合物试验孔ZK1井及其周边钻孔的岩心顶空气、岩心解析气以及湖水气进行了组分和碳同位素测试分析,同时对ZK1井及其周边钻孔岩心中的碳酸盐岩碳同位素进行了测试分析。测试结果显示:该区天然气主要成分为二氧化碳,其含量在98%以上,烃类气体(主要为甲烷)含量很少;二氧化碳碳同位素主频在-4‰～-6‰(VPDB)之间,少量富烃样品的甲烷碳同位素主频介于-3238‰～-2782‰（VPDB）之间,碳酸盐岩的碳同位素平均值为-387‰（VPDB）。综合分析认为,研究区二氧化碳主要为幔源成因,可能与该区强烈的构造运动和岩浆活动有关。     

重庆地区岩溶地下河水溶解无机碳及其稳定同位素特征

稳定碳同位素是指示岩溶动力系统碳来源及转化的重要指标。为揭示重庆地区岩溶地下水中溶解无机碳基本特征和碳来源,本文对该地区63条岩溶地下河水样进行了水化学和碳同位素分析。研究结果表明,重庆地区地下河水溶解无机碳主要表现形式为HCO3-,雨季由于稀释作用其浓度低于旱季。重庆岩溶地下河水δ13C-DIC（V-PDB）旱季变化范围为-15.34 ‰～-5.89 ‰,雨季变化范围为-17.40 ‰～-4.23 ‰。根据δ13C同位素质量平衡方法,计算得到重庆地下河旱季碳酸盐岩溶蚀对DIC贡献为45.1 % ～79.7 %,雨季平均为34.6 %～82.1 % 。计算结果表明,在人类活动不断增强的情况下,岩溶水体DIC通量中碳酸盐岩溶解来源的DIC和其参与岩溶地下水δ13C值的形成并不一定是岩溶作用理论方程中所计算的50 %,而是有一定的变化范围。因此在计算岩溶作用碳汇时,建议通过δ13C值扣除碳酸盐岩溶蚀形成DIC的通量后再来推算岩溶作用形成的碳汇量。      

Storage and density of soil organic carbon in urban topsoil of hilly cities: A case study of Chongqing Municipality of China

Rapid urbanization results in the conversion of natural soil to urban soil,and consequently,the storage and density of the soil carbon pools change.Taking Chongqing Municipality of China as a study case,this investigation attempts to better understand soil carbon pools in hilly cities.First,the vegetated areas in the study area were derived from QuickBird images.Then,topsoil data from 220 soil samples(0-20 cm) in the vegetated areas were collected and their soil organic carbon(SOC) densities were analyzed.Using the Kriging interpolation method,the spatial pattern of SOC was estimated.The results show that the SOC density exhibited high spatial variability in the urban topsoil of Chongqing.First,the SOC density in topsoil decreased according to slope in the order 2°-6° < 25°-90° < 0°-2° < 6°-15° < 15°-25°.Second,the newly developed areas during 2001-2010 had a lower SOC density than the areas built before 1988.Third,urban parks and gardens had a higher SOC density in topsoil,residential green land followed,and scattered street green land ranked last.For hilly cities,the variability of terrain affects the distribution of SOC.The Kriging results indicate that Kriging method combining slope with SOC density produced a high level of accuracy.The Kriging results show that the SOC density to the north of the Jialing River was higher than the south.The vegetated areas were estimated to amount to 73.5 km2 across the study area with an SOC storage of 0.192 Tg and an average density of 2.61 kg/m2.     

Labile organic matter content and distribution as affected by six-year soil amendments to eroded Chinese mollisols

Labile organic carbon （LOC） is a fraction of soil organic carbon （SOC） with rapid turnover time and is affected by soil fertilization. This investigation characterized the SOC content, LOC content and LOC distribution in the treatment plots of surface soil erosion at five levels （0-, 5-, 10-, 20- and 30-cm erosion）. The soil had received contrasting fertilizer treatments （i.e., chemical fertilizer or chemical fertilizer ＋ manure） for 6 years. This study demonstrated that both SOC and various LOC fractions contents were higher in the plots with fertilizer ＋ manure than in those with fertilizer alone under the same erosion conditions. The SOC and LOC contents de- creased as the erosion depth increased. Light fraction organic carbon, particulate organic carbon, easily oxidizable organic carbon （KMnO4-oxydizable organic carbon）, and microbial biomass carbon were 27% 57%, 37%-7%, 20%-25%, and 29%-33% higher respectively in the fertilizer ＋ manure plots, than in the fertilizer alone plots. Positive correlations （p 〈 0.05） between SOC content and different fractions contents were observed in all plots except the correlation between total SOC content and water-soluble organic carbon content in the different fertilization treatments. Obviously, fertilizer ＋ manure treatments would be conducive to the accumulation of LOC and SOC in the Black soil of Northeast China.     

Effects of soil compaction,rain exposure and their interaction on soil carbon dioxide emission

Soils release more carbon, primarily as carbon dioxide (CO₂), per annum than current global anthropogenic emissions. Soils emit CO₂ through mineralization and decomposition of organic matter and respiration of roots and soil organisms. Given this, the evaluation of the effects of abiotic factors on microbial activity is of major importance when considering the mitigation of greenhouse gases emissions. Previous studies demonstrate that soil CO₂ emission is significantly affected by temperature and soil water content. A limited number of studies have illustrated the importance of bulk density and soil surface characteristics as a result of exposure to rain on CO₂ emission, however, none examine their relative importance. Therefore, this study investigated the effects of soil compaction and exposure of the soil surface to rainfall and their interaction on CO₂ release. We conducted a factorial laboratory experiment with three soil types after sieving (clay, silt and sand soil), three different bulk densities (1·1 g cm^–3, 1·3 g cm^–3, 1·5 g cm^–3) and three different exposures to rainfall (no rain, 30 minutes and 90 minutes of rainfall). The results demonstrated CO₂ release varied significantly with bulk density, exposure to rain and time. The relationship between rain exposure and CO₂ is positive: CO₂ emission was 53% and 42% greater for the 90 minutes and 30 minutes rainfall exposure, respectively, compared to those not exposed to rain. Bulk density exhibited a negative relationship with CO₂ emission: soil compacted to a bulk density of 1·1 g cm^–3 emitted 32% more CO₂ than soil compacted to 1·5 g cm^–3. Furthermore we found that the magnitude of CO₂ effluxes depended on the interaction of these two abiotic factors. Given these results, understanding the influence of soil compaction and raindrop impact on CO₂ emission could lead to modified soil management practices which promote carbon sequestration. Copyright © 2012 John Wiley & Sons, Ltd.     

Removal of Pyridine from Aqueous Solution by Adsorption on an Activated Carbon Cloth

Pyridine is a very toxic pollutant that has to be removed from wastewater. In this work, adsorption of pyridine on activated carbon cloth (ACC) is studied as a possible alternative for eliminating pyridine from aqueous solution. The ACC was produced from polyacrylonitrile. The adsorption equilibrium data of pyridine on ACC was obtained in a batch adsorber. The experimental data was interpreted with the isotherms of Langmuir, Freundlich, and Prausnitz‐Radke (PR), and the PR isotherm better represented the experimental data. The capacity of ACC for adsorbing pyridine was favored increasing the solution pH from 3 to 6, and this effect was due to the π–π dispersive and electrostatic interactions between the pyridine species in solution and the surface complexes of ACC. The modified Langmuir model fitted reasonably well the influence of pH on the adsorption capacity. In this model was assumed that both neutral pyridine and pyridinium were simultaneously adsorbed on ACC accordingly to the experimental results. The adsorption capacity was almost independent of temperature. The reversibility study revealed that 75% of the pyridine can be desorbed from ACC indicating that part of the pyridine was irreversibly adsorbed, and possibly chemisorbed.     

雷州半岛红树林边缘效应及其对海岸有机碳库的影响

作为滨海湿地与邻近海区之间物质循环、能量和物种流动及其相互作用的重要界面,红树林的边缘效应对研究海陆生态系统相互作用,滨海湿地生物地貌形成过程以及海岸带有机碳库分布格局等方面的具有重要意义。文章以雷州半岛东岸红树林4种典型地貌分布区为重点,通过调查红树林前缘光滩,林缘及林内植被及土壤理化特征的变化,探讨红树林边缘效应的表现及其对土壤有机碳库的影响。结果表明,不同地貌类型红树林边界区的群落结构及土壤理化因子分布特征有所不同。边界区群落特征表现为林缘的冠层低于林内,叶面积指数低于林内,物种丰富度林内高于林缘(除河口区外),且林缘的植被盖度受风浪影响显著,表现出河口区>内湾区>岛屿区>前沿浪击区。土壤理化性质边缘效应表现为林缘的pH值、粒度低于光滩,氧化还原电位、盐度高于光滩(除内湾区外),而林内的土壤理化性质波动较大,可能受林缘植被演替及地貌双重影响。不同地貌单元红树林边界区的土壤表层有机碳含量,有机碳密度均表现为林内>林缘>光滩。综合影响表层土壤有机碳的主要生物及非生物因子进行主成分分析和相关分析,结果显示土壤表层有机碳密度与环境第一主成分呈显著负相关,即受植被盖度,叶面积指数和土壤pH因子影响密切。红树林土壤有机碳沉积虽然受到不同水文地貌的影响,但总体而言,红树林初级生产输入和土壤酸性环境对红树林林下土壤有机碳库的富存贡献显著。     

Habitat heterogeneity influences cold‐seep macrofaunal communities within and among seeps along the Norwegian margin – Part 2: contribution of chemosynthesis and nutritional patterns

The relative contribution of chemosynthesis in heterotrophic fauna at seeps is known to be influenced by depth and by habitat. Using stable isotopes of carbon and nitrogen, we investigated macro‐ and megafaunal nutritional patterns in Norwegian margin cold seeps by comparing food webs both among habitats within a seep site and between different sites. The very active Håkon Mosby mud volcano (HMMV) is characterized by geochemical gradients, microbial activity and faunal zonation from the centre to the periphery. The Storegga Slide (600–900 m depth) has pockmarks with patchy less active seeps, and also shows concentric zonation of habitats but at much smaller spatial scale. The dominant carbon source for macrofaunal nutrition in both areas was chemosynthetically fixed and the bulk of organic carbon was derived from sulphur‐oxidizing bacteria. In HMMV, food chains were clearly separated according to habitats, with significantly lighter δ¹³C signatures on microbial mats and adjacent sediment (?33.06 to ?50.62‰) than in siboglinid fields (?19.83 to ?35.03‰). Mixing model outputs revealed that the contribution of methane‐derived carbon was small in siboglinid fields (0–17%) but significant (39–61%) in the microbial mats. Moreover, the variability of macrofauna signatures within this later habitat suggests the co‐occurrence of two food chains, one based on primary production via methanotrophy and the other via sulphide oxidation. The length of the food chains also varied among habitats, with at least one more trophic level in the siboglinid fields located at the periphery of the volcano. Conversely, in Storrega pockmarks, faunal δ¹³C signatures did not vary among habitats but among species, although separate food chains seem to co‐occur. The small size of the seepage areas and their lower fluxes compared to HMMV allow more background species to penetrate the seep area, increasing the range of δ¹⁵N and the trophic level number. Probably due to the higher flux of photosynthetic particulate organic carbon, the overall chemosynthesis‐based carbon contribution in invertebrate nutrition was lower than that in HMMV.     

中太平洋富钴结壳中生物标志物、有机碳同位素地球化学及其古海洋环境意义

利用2003年大洋DY105-12,14航次在中太平洋海山获取的KXD28富钴结壳样品,采用气相色谱(GC)内标法对该结壳样品的分层样进行了可溶有机质(氯仿沥青“A”)及其族组成(饱和烃、芳烃、非烃)、正构烷烃、类异戊二烯烃的定量分析,并结合总有机碳(TOC)及有机碳同位素(δ¹³C)分析,探讨了结壳样品有机质来源及富钴结壳组成与生长环境之间的关系。结果表明:(1)富钴结壳中有机质生物母源主要为海洋生物和菌藻类,并混有少量陆源物质;有机碳同位素同样也指示了海洋水生生物碳同位素特征;(2)KXD28结壳从底层到最外层有机碳同位素发生了很大变化,结壳中有机碳同位素组成变化与结壳生长过程中的海洋环境气候相符合:富钴结壳生长前期δ¹³C组成由正变负,对应全球气候变冷,南极底层流向太平洋挺进;而富钴结壳生长后期δ¹³C逐渐偏正,与全球气候变暖和南极底层流萎缩相关联。