重庆地区岩溶地下河水溶解无机碳及其稳定同位素特征   总被引：6，自引：3，他引：3  

蒲俊兵 《中国岩溶》2013,32(2):123-132

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。   相似文献   

Storage and density of soil organic carbon in urban topsoil of hilly cities: A case study of Chongqing Municipality of China   总被引：1，自引：1，他引：0  

LIU Yong  WANG Cheng  YUE Wenze  HU Yanyan 《中国地理科学(英文版)》2013,23(1):26-34

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.  相似文献   

Distribution of dissolved inorganic nitrogen over the continental slope of the Yellow Sea and East China Sea     

张璇  石晓勇  温婷婷  张传松  韩秀荣 《中国海洋湖沼学报》2013,31(1):227-236

Based on survey data from April to May 2009, distribution and its influential factors of dissolved inorganic nitrogen (DIN) over the continental slopes of the Yellow Sea (YS) and East China Sea (ECS) are discussed. Influenced by the Changjiang (Yangtze) River water, alongshore currents, and the Kuroshio current off the coast, DIN concentrations were higher in the Changjiang River estuary, but lower (<1 μmol/L) in the northern and eastern YS and outer continental shelf area of the ECS. In the YS, the thermocline formed in spring, and a cold-water mass with higher DIN concentration (about 11 μmol/L) formed in benthonic water around 123.2°E. In Changjiang estuary (around 123°E, 32°N), DIN concentration was higher in the 10 m layer; however, the bottom DIN concentration was lower, possibly influenced by mixing of the Taiwan Warm Current and offshore currents.  相似文献   

Labile organic matter content and distribution as affected by six-year soil amendments to eroded Chinese mollisols   总被引：2，自引：0，他引：2  

Yueyu Sui  Xiaoguang Jiao  Wenting Chen  Xiaobing Liu  Xingyi Zhang  Guangwei Ding 《中国地理科学(英文版)》2013,23(6):692-699

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.  相似文献   

A Comprehensive Method for Fractionating Soil Organic Matter Not Protected and Protected from Decomposition by Physical and Chemical Mechanisms     

César Plaza  José M. Fernández  Engil I. P. Pereira  Alfredo Polo 《洁净——土壤、空气、水》2012,40(2):134-139

The objective of this work was to describe a method for isolating meaningful and measurable soil organic matter (SOM) pools that differ in the mechanisms by which they are protected from decomposition. The proposed method is appropriate for soil C stabilization and sequestration studies. Unlike previous fractionation schemes, this procedure allows free SOM located between aggregates (unprotected C pool) and SOM occluded within both macroaggregates and microaggregates (C weakly and strongly protected by physical mechanisms, respectively) to be recovered separately, freed from the soil mineral matrix and the mineral‐associated SOM pool (C pool protected by chemical mechanisms) and thus well suited to advanced chemical characterization by ¹³C‐NMR. Briefly, free SOM is isolated by an initial density separation. Stable macroaggregates are broken up into stable microaggregates and intra‐macroaggregate SOM, which is then separated by density. Finally, intra‐microaggregate SOM is isolated from mineral‐associated SOM by a third density separation after ultrasonic disruption. The SOM dissolved during the fractionation procedure is also recovered. Results obtained on soil samples with contrasting textures suggested that clay content induces a decrease of the proportion of free organic C and an increase of mineral‐associated organic C content. Free SOM is characterized by a marked presence of undecayed organic material and biologically labile substances, such as carbohydrates and proteins. In contrast, SOM occluded within aggregates, especially within microaggregates, represents a more decomposed fraction, relatively enriched in unsubstituted‐aliphatic material, most probably lipid biopolymers.  相似文献   

雷州半岛红树林边缘效应及其对海岸有机碳库的影响   总被引：1，自引：0，他引：1  

杨娟  JAY Gao  刘宝林  ALAN Cheung  王铎  张苇 《海洋学报》2012,34(5):161-168

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。  相似文献   

南黄海悬浮体浓度的平面分布特征及其输运规律   总被引：3，自引：1，他引：2  

韦钦胜  刘璐  臧家业  冉祥滨 《海洋学报》2012,34(2):73-83

重点分析和探讨了南黄海悬浮体浓度的平面分布及其水平输运,结果显示悬浮体浓度具有显著的空间区域化分布特征,其与该海域环流场的布局和季节转换存在良好的对应关系,南黄海环流是该海域悬浮体运移的主要动力和控制因素;江苏近岸海域在一年四季均为悬浮体浓度的最高值区,其悬浮体主要来源于潮流和海浪所引起的沉积物再悬浮以及苏北沿岸水的携带和输送,而且夏季悬浮体在该海域的累积还可为冬半年在黄海西部沿岸流作用下将其输运至东南海域提供很好的物源保证;长江口东北部海域在春、夏、秋三季出现东北向扩展的高值区,体现了长江冲淡水的影响;石岛外海在冬、春、秋三季也存在悬浮体浓度高值区,并具有向南黄海中部泥质区扩展的态势,这是鲁北沿岸流将现代黄河物质输运至此的结果。发现调查海域中部表底层在春秋季均存在云团状高值区,而且该海域悬浮体浓度自春季至秋季出现"双峰现象",这与春秋季水华期间浮游植物繁殖所产生的有机碎屑有关,并使作为悬浮体组成的海洋浮游生物有机质向沉积物转移,据此进一步指出这一物源可能对南黄海冷涡泥质区的形成、发育也具有一定的作用,该观点深化了对南黄海中部冷涡泥质区受上层生物活动影响以及泥质区物源的认识。  相似文献   

2009-2010年冬季南海东北部中尺度过程观测   总被引：2，自引：1，他引：1  

刘长建  庄伟  夏华永  杜岩 《海洋学报》2012,34(1):8-16

根据南海北部陆架陆坡海域2009-2010年冬季航次的CTD调查资料,发现西北太平洋水在上层通过吕宋海峡入侵南海,其对南海东北部上层水体温盐性质的影响自东向西呈减弱趋势,影响范围可达114°E附近。入侵过程中受东北部海域反 气旋式涡旋(观测期间,其中心位于20.75°N,118°E附近) 的影响,海水的垂向和水平结构发生了很大变化,特别是涡旋中心区域,上层暖水深厚,混合层和盐度极大值层显著深于周边海域。该暖涡在地转流场、航载ADCP观测海流及卫星高度计资料中均得到了证实。暖涡的存在还显著影响了海水化学要素的空间分布,暖涡引起的海水辐聚将上层溶解氧含量较高的水体向下输运,使次表层的暖涡中心呈现高溶解氧的分布特征。  相似文献   

Food web structure within kelp holdfasts (Laminaria): a stable isotope study     

Gauthier Schaal  Pascal Riera  Cédric Leroux 《Marine Ecology》2012,33(3):370-376

Kelp holdfasts are highly reticulated structures which host a large diversity of small fauna. These microhabitats have been reported to play a crucial role in the biodiversity associated to kelp forest ecosystems. This study aimed at identifying trophic links and the main food sources sustaining food webs within communities associated with kelp holdfasts, through a stable isotope (δ¹³C and δ¹⁵N) approach. Sampling of the main invertebrates inhabiting Laminaria digitata holdfasts, and of their potential food sources, took place in February and May 2007. Stable isotope results reveal that most of the primary consumers, including filter-feeders and deposit-feeders, rely on the particulate organic matter sedimented within kelp holdfasts. Only three grazers departed from this general pattern. The correspondence between the stable isotope ratios of predators and sediment consumers indicated that this source is at the base of the main pathway through which energy and matter transit in the food web. δ¹⁵N ranges found for consumers revealed that the food web associated with kelp holdfasts is composed of 3.5 levels. In spite of the low diversity of food sources at the base of the food web, these microhabitats can therefore be considered micro-scale ecosystems, from a functional perspective.  相似文献   

胶州湾大沽河口潮间带沉积物中叶绿素和有机质含量的季节变化   总被引：1，自引：0，他引：1  

尹盛乐  刘晓收  袁超  谭朋  胡金  刘阳  董树刚 《海洋湖沼通报》2012,(2):97-106

为了解胶州湾大沽河口潮间带沉积物中底栖微藻和有机质含量的季节变化,于2010年4月至2011年2月,分4次(春、夏、秋、冬)测定分析了沉积物中的叶绿素含量和有机质含量,并分析了沉积物的粒度组成及现场温度。结果表明,表层(0～2cm)沉积物叶绿素a含量为0.42～6.06mg/kg,有机质含量为0.48%～3.71%;次表层(2～5cm)叶绿素a含量为0.13～3.53mg/kg,有机碳质量为0.31%～3.78%;深层(5～8cm)叶绿素a含量为0.14～1.95mg/kg,有机质含量为0.47%～3.72%。经统计检验和Pearson相关性分析得出,胶州湾大沽河口沉积物中的叶绿素a含量春冬两季最高,夏季和秋季最低;叶绿素a含量与深度和温度呈负相关;与所处潮带、有机质含量、粉砂黏土含量在本实验中均无显著的相关性;有机质含量与季节关系不大,高潮带最高,其含量与粉砂黏土含量呈正相关,与叶绿素含量、深度和温度关系不明显。  相似文献