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1.
长江口潮滩有机质来源的C、N稳定同位素示踪 总被引：25，自引：0，他引：25
依据长江河口潮滩自然环境特征和受人文活动影响的差异性,沿长江河口南岸潮滩选取了12个典型的监测站位,并分别于洪水季节 (7月份) 和枯水季节 (2月份) 在各监测站位进行了表层 (0~2 cm) 沉积物样品的采集。对表层沉积物有机质中稳定碳、氮同位素进行分析与测试发现,7月份稳定碳同位素值普遍低于2月份的稳定碳同位素值,其变化范围分别为 -29.8‰ ~ -23.7‰和-27.3‰ ~ -25.6‰;7月份和2月份稳定氮同位素分别为1.0‰ ~ 5.5‰和1.7‰~ 7.8‰。研究区域内,稳定碳、氮同位素的地区分布和季节变化特征揭示,有机质中的稳定碳、氮同位素组成不仅受陆源和海源有机质输入量之间消长变化的影响,同时一系列的生物地球化学过程、人为有机质的输入和沉积物粒度与叶绿素对碳、氮同位素组成均存在不同程度的改造作用。此外,利用稳定碳同位素质量平衡混合模型,还对陆源有机质输入量的贡献率进行了初步定量估算。 相似文献
2.
《中国地理与资源文摘》2005,(1)
X13,X14 4 2 0 0 5 0 10 0 6 6长江口潮滩有机质来源的C、N稳定同位素示踪 =CarbonandnitrogenstableisotopesastracerstosourceorganicmatterintheYangtzeEstuary/刘敏 ,侯立军…∥地理学报 .—2 0 0 4 ,5 9(6 ) .— 918～ 92 6依据长江河口潮滩自然环境特征和受人文活动影响的差异性 ,沿长江河口南岸潮滩选取了 12个典型的监测站位 ,并分别于洪水季节 (7月份 )和枯水季节 (2月份 )在各监测站位进行了表层 (0 - 2cm)沉积物样品的采集 .对表层沉积物有机质中稳定碳、氮同位素进行分析与测试发现 ,7月份稳定碳同位素值普遍低于 2月份的稳… 相似文献
3.
党河流域敦煌盆地地下水补给与演化研究 总被引：3，自引：0，他引：3
综合应用水文地球化学指标和稳定同位素技术研究了党河流域敦煌盆地地下水补给和演化规律。岩盐、石膏及芒硝等矿物的溶解对Na+、Ca2+、Cl-及SO42-离子浓度影响较大。阳离子交换作用明显,地下水中Mg2+和Ca2+浓度增加,并与碳酸盐发生沉淀,导致HCO3-减少。地下水的δ18O值介于-12.1‰~-7.5‰,δ2H值变化范围为-84.3‰~-61.5‰,指示了盆地不同地带地下水补给来源不同。潜水δ18O和δ2H数值随着地下水径流路径方自西南到东北越来越富集,反映了蒸发浓缩效应,南湖、盆地南部潜水同位素与河水相近,体现了现代补给。相比之下,承压水稳定同位素相对贫乏,指示过去寒冷时期的补给。该研究可以为敦煌区域地下水资源规划和管理提供一定的借鉴意义。 相似文献
4.
西江河口段溶解无机碳稳定同位素组成的时空变化 总被引：2，自引：0，他引：2
从2006 年9 月至2007 年6 月间对西江河口段溶解无机碳稳定同位素组成(δ13CDIC) 及 其相关的水体理化参数进行了一个水文年的季节性采样调查。夏、秋两季δ13CDIC 平均值(-13. 91‰、-13.09‰) 小于春、冬季节(-11.71‰、-12.26‰), 呈现出明显的季节性。δ13CDIC 与温度 呈负相关(p = 0.000; r = -0.646), 而与氧化还原电位正相关(p = 0.000; r = 0.569), 表明河段 表层水体δ13CDIC 受到季节性变化的水体理化性质等河道有机质氧化分解条件的控制; 夏季洪水期δ13CDIC 与航测距离呈正相关, 而春季枯水期的δ13CDIC 与航测距离负相关。δ13CDIC 的这种时空变异证明了研究河段河- 海作用过程影响了水体的理化性状进而控制了河道表层水体DIC 的性质。研究河段δ13CDIC 的上述时空分布规律与流域所处的地理环境关系密切, 汛期的夏季受陆源有机质的强烈分解作用的影响, DIC 的同位素组成向海洋方向变轻; 枯期的春季因海洋作用加强以及咸潮的入侵, 河道DIC 的同位素组成向海洋方向变重。 相似文献
5.
长江口盐沼土壤有机质更新特征的滩面趋势 总被引：9，自引：0，他引：9
通过对长江口崇明东滩高潮滩、中潮滩以及光滩柱状样的有机元素(C、N)含量与碳稳定同位素组成(δ13C)、粒度组成等的测定,研究盐沼土壤有机质更新特征及其滩面趋势.结果表明,长江口盐沼土壤POC-δ13C相关特征与山地土壤剖面上部土层的基本类似,盐沼土壤有机质主要源于长江流域表层土壤,有机质年龄不足100年.不同高程柱样TN-C/N、POC-TIC与POC-δ13C关系特征表明盐沼土壤有机质更新程度普遍较低,有机质更新特征呈明显的滩面变化趋势.光滩有机质基本反映沉积母质特征,更新程度极低;中、高潮滩有机质更新作用已经发生,随着滩面演变,处于不同更新阶段的有机质组分混杂程度提高.盐沼滩面过程塑造垂向沉积层序,层序中独特的沙、泥纹层构造导致物质上下运移困难,有机质更新作用受到抑制.盐沼滩面过程直接影响有机质的累积与更新,对于有机质更新的时空特征具有显著制约. 相似文献
6.
哈萨克斯坦是中亚干旱-半干旱地区最大的内陆国家,东部以阿尔泰山、天山与我国相隔,区内河流众多,是该国水资源的主要来源地,额尔齐斯河、伊犁河是中哈两国重要的跨境河流。通过对哈萨克斯坦东部不同区域河水和湖水的主要离子、氢、氧同位素分析,初步研究了该区域的水化学和同位素空间分布特征及其对地表水循环的指示意义。结果表明：哈萨克斯坦东部河水离子组成以HCO3-Ca为主,局部有HCO3-Na水型分布。湖水以SO4-Na为主,有少量HCO3-Ca和SO4-Ca型水。研究区内水体Ca2+、Na+、SO42-均表现出南北低中间高的空间特征。河水氢、氧同位素变化范围分别为-123.46‰～-71.22‰和-16.09‰～-10.21‰,湖水氢、氧同位素变化范围分别为-97.82‰～-9.20‰和-12.74‰～2.44‰。额尔齐斯河河水与周围补给水体的氢、氧同位素差异显著,表明其主要来源于上游补给。河水和湖水氢、氧同位素关系式分别为δD=7.546×δ18O+3.507和δD=5.737×δ18O-24.14,且河水氢、氧同位素与经、纬度显著相关,反映了明显的内陆效应,而湖水氢、氧同位素的变化则主要反映了水体的蒸发程度,水体氢、氧同位素变化敏感地示踪了该区域水体的来源与循环特征。 相似文献
7.
中国北方干旱半干旱区表土的有机质碳同位素、磁化率与年降水量的关系 总被引：4，自引：0，他引：4
古土壤和湖泊中的有机质碳同位素与磁化率指标被广泛应用于古气候的重建。但由于各地自然条件的差异,其气候意义具有一定的区域性。通过对中国秦岭到内蒙古北部的中蒙边境(34°N～43°N)连续剖面上的102个采样点的表层土壤样品的有机质碳同位素和磁化率进行测定,并搜集了该区域部分站点的降水资料。研究表明有机质碳同位素波动在-22‰～-30‰之间,其碳同位素值与降水量存在显著的线性负相关关系。磁化率与年均降水量也存在显著的函数关系,总体上磁化率随着年降水量的增加而增加。研究进一步证明,在中国干旱和半干旱区,表土中的有机质碳同位素δ13C和磁化率对年降水量具有显著的指示作用,因此可以用古土壤中的有机质碳同位素和磁化率作为代用指标,来反映古降水的变化。 相似文献
8.
对研究区内第五次北极科学考察所取的表层海水颗粒物的浓度、显微组成、有机碳、氮含量及其同位素组成进行了分析。结果表明,楚科奇海域表层海水颗粒物浓度介于0.56—4.01 mg·L-1,具有冰区边缘高于开阔水域的特点。陆架区颗粒有机质相对含量高(TOC:9.78%—20.24%;TN:0.91%—2.31%),有机碳、氮同位素值相对重(δ13C:-23.29‰—-26.33‰PDB;δ15N:6.14‰—7.78‰),有机质主要来源于海洋生物,含有部分陆源有机质;陆坡及北冰洋核心区的颗粒有机质含量,除SR15站外,相对低(TOC:8.06%—8.96%;TN:0.46%—0.72%),有机碳、氮同位素值轻(δ13C:-26.93‰—-27.78‰PDB;δ15N:4.13‰—4.84‰),颗粒物有机质以陆源为主。陆坡区SR15站表层海水颗粒物中异常高的陆源有机质(TOC:27.94%,TN:1.16%;δ13C:-27.43;δ15N:3.81)可能来自源于东西伯利亚的穿极洋流。海冰携带的颗粒物(包括冰藻)是冰区边缘表层海水颗粒物的重要来源,在陆架区海冰融化,向水体中释放了大量生物体;而陆坡区和北冰洋核心区,海冰对颗粒物的贡献以碎屑矿物和黏土矿物为主。 相似文献
9.
阜康典型荒漠C3植物稳定碳同位素值的环境分析 总被引：26，自引：3，他引：23
通过对阜康典型荒漠C3植物稳定碳同位素值的分析。叶片炭同位素值在-23‰和-29‰之间变化,其中主要在-27‰附近波动。这与前人报道的世界上其他地区荒漠植物碳同位素值的变化非常一致。降水可以改变叶片碳同位素值的大小,降水越多,叶片碳同位素值越负,它们的变化幅度有物种的依赖性。叶片碳同位素值也受植物生长形式或期望寿命的影响,木本植物或寿命长的植物叶片碳同位素值要高。分析表明,利用该区土壤或陆相沉积中有机质碳同位素值可以判断气候的干湿变化：土壤或陆相沉积中有机质碳同位素值越高,气候则越干燥。 相似文献
10.
为探讨极端天气降水中稳定同位素的变化,应用2015年9号台风“灿鸿”影响期间中国东部沿海城市台北、温岭、海宁、南通降水中稳定同位素资料,分析降水中稳定同位素的时空变化。结果表明：台风“灿鸿”影响期间,台北降水的δ18O平均值为-4.40‰,为最高值;温岭降水δ18O的平均值最低,为-9.80‰;海宁与南通降水的δ18O平均值居于两者之间,分别为-8.83‰和-7.88‰。4地降水δ18O均呈现出2个阶段的“厂”型变化特征。“灿鸿”降水δ18O值在时空分布上冲刷效应明显,采样站点距离台风中心越近降水δ18O值越低d值越高。台风灿鸿影响期间整个降水过程以湿润的热带海洋气团为主,台北阶段1降水受台风外围云系影响,降水的冲刷程度较轻,δ18O值偏高;台北阶段2降水与温岭降水受单一水汽团冲刷效应影响,降水δ18O不断降低;海宁和南通与灿鸿中心的距离基本相似,且水汽源相同,降水δ18O值波动比较接近。 相似文献
11.
长江口外海域沉积物中有机物的来源及分布 总被引：10，自引：0，他引：10
通过分析长江口外海域不同区域有机碳和氮的分布特征及其影响因素,了解了底部沉 积物中有机碳和氮同位素的生物地球化学特征,探讨二者对长江口外海域底部沉积物中有机 物来源的指示意义。运用质量混合模型,计算了长江输入的陆源有机物的贡献及其空间变化。结果表明,长江口外海域沉积物中TOC 和TN 的分布和东海陆架的环流体系有着密切关系, 与环流的分布相对应,如果大致沿31oN 和123oE 作为分界线, 整个研究区的TOC 和TN 的分布可划分为4 个具有不同分布特征的区域。TOC、TN、δ13C 和δ15N 分别与沉积物的平均粒 径呈线性相关关系,因此,粒度效应是控制长江口外海域沉积物中有机物分布和稳定同位素 碳、氮的一个重要因素。研究区内的C/N 比值能够在一定程度上体现有机物的来源信息,但δ15N 表现出了与C/N 和δ13C 不同的区域分布和变化特征。陆源有机物来源比重较高的区域与 长江口外海域赤潮突发频率最高的地区相对应。长江口附近沉积物中的陆源有机物来源最高, 超过了50%,且等值线呈舌状向东北方向凸出,表明了长江冲淡水的影响。陆源颗粒态有机物沉海底后,要不断经历早期成岩作用和生物作用,因此在在相同地点,陆源有机物对沉积物中有机物的贡献,要明显小于对悬浮颗粒态有机物的贡献。 相似文献
12.
The spatial distribution patterns of total organic carbon and total nitrogen show significant correlations with currents of the East China Sea Shelf. Corresponding to distribu-tions of these currents, the study area could be divided into four different parts. Total organic carbon, total nitrogen, and organic carbon and nitrogen stable isotopes in sediments show linear correlations with mean grain size, respectively, thus “grain size effect” is an important factor that influences their distributions. C/N ratios can reflect source information of organic matter to a certain degree. In contrast, nitrogen stable isotope shows different spatial distri-bution patterns with C/N and organic carbon stable isotope, according to their relationships and regional distributions. The highest contribution (up to 50%) of terrestrial organic carbon appears near the Changjiang Estuary with isolines projecting towards northeast, indicating the influence of the Changjiang dilution water. Terrestrial particulate organic matter suffers from effects of diagenesis, benthos and incessant inputting of dead organic matter of plankton, after depositing in seabed. Therefore, the contribution of terrestrial organic carbon to par-ticulate organic matter is obviously greater than that to organic matter in sediments in the same place. 相似文献
13.
长江口外海域沉积物中有机物的来源及分布 总被引：1，自引：1，他引：0
The spatial distribution patterns of total organic carbon and total nitrogen show significant correlations with currents of the East China Sea Shelf. Corresponding to distributions of these currents, the study area could be divided into four different parts. Total organic carbon, total nitrogen, and organic carbon and nitrogen stable isotopes in sediments show linear correlations with mean grain size, respectively, thus ＂grain size effect＂ is an important factor that influences their distributions. C/N ratios can reflect source information of organic matter to a certain degree. In contrast, nitrogen stable isotope shows different spatial distribution patterns with C/N and organic carbon stable isotope, according to their relationships and regional distributions. The highest contribution （up to 50%） of terrestrial organic carbon appears near the Changjiang Estuary with isolines projecting towards northeast, indicating the influence of the Changjiang dilution water. Terrestrial particulate organic matter suffers from effects of diagenesis, benthos and incessant inputting of dead organic matter of plankton, after depositing in seabed. Therefore, the contribution of terrestrial organic carbon to particulate organic matter is obviously greater than that to organic matter in sediments in the same place. 相似文献
14.
Jennifer L. Mays Mark Brenner Jason H. Curtis Kathryn V. Curtis David A. Hodell Alex Correa-Metrio Jaime Escobar Andrea L. Dutton Andrew R. Zimmerman Thomas P. Guilderson 《Journal of Paleolimnology》2017,57(4):307-319
Sediment core PI-6 from Lake Petén Itzá, Guatemala, possesses an ~85-ka record of climate and environmental change from lowland Central America. Variations in sediment lithology suggest large and abrupt changes in precipitation during the last glacial and deglacial periods, and into the early Holocene. We measured stable carbon isotope ratios of total organic carbon and long-chain n-alkanes from the core, the latter representing a largely allochthonous (terrestrial) source of organic matter, to reveal past shifts in the relative proportion of C3–C4 terrestrial biomass. We sought to test whether stable carbon isotope results were consistent with other paleoclimate proxies measured in the PI-6 core, and if extraction and isotope analysis of n-alkanes is warranted. The largest δ13C variations are associated with Heinrich Events. Carbon isotope values in sediments deposited during the last glacial maximum indicate moderate precipitation with little fluctuation. The deglacial was a period of pronounced climate variability, e.g. a relatively warm and moist Bølling–Allerød, but a cool and dry Younger Dryas. Arid periods of the deglacial were inferred from samples with high δ13C values in total organic carbon, which reflect times of greater proportions of C4 plants. These inferences are supported by stable isotope measurements on ostracod shells and relative abundance of grass pollen from the same depths in core PI-6. Similar trends in carbon stable isotopes measured on bulk organic carbon and n-alkanes suggest that carbon isotope measures on bulk organic carbon in sediments from this lake are sufficient to infer past climate-driven shifts in local vegetation. 相似文献
15.
Alexander M. Heyng Christoph Mayr Andreas Lücke Bernd Striewski Stefan Wasteg?rd Holger Wissel 《Journal of Paleolimnology》2012,48(2):351-366
Maar lakes in the Auckland Volcanic Field are important high-resolution archives of Holocene environmental change in the Southern Hemisphere mid-latitudes. Stable carbon and nitrogen isotope analyses were applied on bulk organic matter and the green alga Botryococcus from a sediment core from Lake Pupuke (Auckland, North Island, New Zealand) spanning the period since 7,165?cal.?year BP. The origin of organic matter was established using total-organic?Ccarbon-to-nitrogen ratios (TOC/TN) as well as organic carbon (??13COM) and nitrogen (??15N) isotope composition of potential modern sources. This approach demonstrated that the contribution of allochthonous organic matter to the lake sediment was negligible for most of the record. The sedimentary TOC/TN ratios that are higher than Redfield ratio (i.e. >7) are attributed to N-limiting conditions throughout the record. Variations of nitrogen and carbon isotopes during the last 7,165?years are interpreted as changes in the dominant processes in the lake. While epilimnetic primary productivity controlled isotope composition before 6,600?cal.?year BP, microbial processes, especially denitrification and methane oxidation, caused overall shifts of the ??15N and ??13C values since the Mid-Holocene. Comparisons with climate reconstructions from the Northern Island suggest that changes in the wind-induced lake overturn and a shift to more pronounced seasonality were the most likely causes for lake-internal changes since 6,600?cal.?year BP. 相似文献
16.
Seasonal distributions of suspended matter and their sedimentary effect on the Changjiang Estuary mud area of the East China Sea were discussed, based on three cruise data of total suspended matter, temperature and salinity collected from the Changjiang Estuary and its adjacent area in summer and winter. The results show that the basic pattern of distributions of suspended matter in the study area is almost the same in winter and in summer. Sediments from Changjiang (Yangtze River) to the sea are chiefly trapped to the west of 123o15'E due to a strong obstruction of the Taiwan Warm Current. This suggests that these sediments are mainly transported and deposited in the inner shelf. The sediment supply, Taiwan Warm Current, and Zhejiang Coastal Current show a strong seasonal variation, which results in a strong seasonal variation of the sedimentary effect on this mud area. This mud area is a "sink" of the Changjiang's sediment discharge to the sea and its sedimentation is stronger in summer and weaker in winter. 相似文献
17.
长江口泥质区的季节性沉积效应 总被引：1，自引：0，他引：1
1IntroductionThe continental shelf of the East China Sea (ECS) is one of the widest shelves in the world. There are several mud areas distributing like patches on a background of widespread coarser ambient sediments of silt and sand on the continental shelf of the ECS. The coastal mud area can be divided into two parts, namely, the Changjiang Estuary mud area (CEMA) in the north and Zhejiang coastal mud area in the south. Between these two parts there is a silt area (Figure 1). The CE… 相似文献
18.
Sanna Vaalgamaa Eloni Sonninen Atte Korhola Kaarina Weckström 《Journal of Paleolimnology》2013,50(2):191-206
We studied the potential for using stable carbon and nitrogen isotope ratios in sediment profiles to trace external nutrient sources and eutrophication at four coastal sites in the Baltic Sea. The sites are characterized by various present and past activities in their catchments, including residential development, sugar processing, agriculture and fish farming. Radiometrically dated sediment cores were analysed for nutrient isotope ratios, organic carbon and total nitrogen. Background information was collected from historical sources, literature and water monitoring data. Despite the multiple organic enrichment sources, it was possible to identify individual sources and processes in the sediment profiles using stable isotope analysis of bulk sediment. The largest changes in δ15N values were seen at sites receiving urban wastewaters. The site that received effluents from a sugar cane (C4-plant) refinery in the past showed a clear effect on δ13C values compared to the site that received wastewater from a sugar beet (C3-plant) factory. Fish farming produced detectable, albeit minor changes in the sediment profile. Slightly lower δ13C values reflected the influence of fish feed and fish metabolism, and higher δ15N values likely indicated the influence of increased sediment denitrification. The land-sea connection via river discharge was observable in the overall δ13C levels of the sediment cores. Our results suggest that temporal changes in sources of organic matter enrichment can be detected in well-dated coastal sediment cores using nutrient stable isotope analyses, even at sites subjected to multiple impacts. There is not, however, a simple relationship between sediment stable isotope profiles and the eutrophication history of our study sites. 相似文献
19.
北极新奥尔松(Ny-lesund)地区环境中有机碳组成来源的初步分析 总被引：1，自引：0，他引：1
对2010年8月从北极新奥尔松地区(Ny-lesund)中国黄河站附近所采集的土壤、沉积物和苔藓进行整体指标[OC%,TN%,δ13C(‰)]和木质素(lignin-derived phenols)分析;并对土壤和沉积物进行粒度分析。结果显示OC%与TN%具有相同的来源;但是粒度并不是控制有机物分布的主要因素。数据显示当地木质素主要来自当地的维管植物和苔藓,但是可能会受到当地动物或者微生物的影响。木质素的降解参数(Ad/Al)v值的大小顺序为沉积物土壤苔藓,可能是由于苔藓的表面吸附了细颗粒的煤炭,但是缺少14C数据,无法定量计算煤炭对环境中有机碳的贡献;另外一个降解参数肉桂基酚类两种单体(CAD/FAD)比值由苔藓、土壤、沉积物依次降低,反映出成岩作用增强,木质素降解程度增加。综合OC%、TN%、δ13C(‰)和木质素数据,中国北极黄河站周围环境中的有机碳来源主要为当地的苔藓和维管植物,也有可能吸附了一些煤颗粒,但是由于技术手段的限制,煤炭的贡献在当前的数据解析下无法定量评估。 相似文献