巢湖四条入湖河流硝态氮污染来源的氮稳定同位素解析   总被引：6，自引：1，他引：5  

刘姝  孔繁翔  蔡元锋  阳振  王济奎  史小丽 《湖泊科学》2012,24(6):952-956

采用氮稳定同位素技术对巢湖四条主要污染输入河流(南淝河、十五里河、派河和双桥河)的氮污染状况和硝态氮来源进行研究.结果表明,巢湖四条入湖河流氮污染最严重的是十五里河,其次是南淝河和派河,双桥河的污染相对较轻.硝态氮的稳定同位素分析结果表明,巢湖四条入湖河流的硝态氮污染物在季节上受到不同因子的影响.十五里河和南淝河的硝态氮污染主要来源于城市生活污水和工业废水;派河的硝态氮污染在冬季主要来源于工业废水,春季来源于农业面源,而在夏季主要受到雨水的影响;双桥河的硝态氮污染冬、春季主要来源于农业面源,夏季主要受雨水的影响.此外本研究结果还表明巢湖四条主要入湖河流的氮污染源主要为铵态氮,因此今后要对铵态氮的来源进行同位素示踪.  相似文献   

赤道西太平洋末次盛冰期以来的浮游有孔虫氧碳稳定同位素记录   总被引：6，自引：0，他引：6  

蒋来宾  翦知湣  成鑫荣 《海洋地质与第四纪地质》2004,24(2):67-71

对西太平洋暖池核心区MD01—2386柱状样最上部5m进行了高分辨率的浮游有孔虫Globigerinoides ruber和Pulleniatina obliquiloculata的氧、碳稳定同位素分析,结合AMS^14C测年,研究表明其属于末次盛冰期-全新世的沉积。赤道西太平洋海区末次盛冰期以来δ^18O值显著降低,但有几次回返事件。表层浮游有孔虫G．ruber比次表层温跃层属种P．obliquiloculata对于环境变化的响应要快,但后者变化的幅度较大。这两个种的氧、碳同位素差值反映出温跃层深度自末次盛冰期以来逐渐加深,并存在周期性的回返事件,说明西太平洋暖池晚第四纪冰期旋回存在气候不稳定性。  相似文献   

塔里木盆地库车坳陷中生界烃源岩生烃动力学参数研究   总被引：6，自引：4，他引：2  

李贤庆  肖贤明  米敬奎  唐永春  肖中尧  刘德汉  申家贵 《煤田地质与勘探》2005,33(4):35-39

根据封闭体系黄金管热模拟实验结果,应用Kinetics专用软件,研究了塔里木盆地库车坳陷中生界不同类型烃源岩的生烃特征与动力学参数。库车坳陷侏罗系煤、碳质泥岩、泥岩及三叠系湖相泥岩具有各自的活化能分布和频率因子,揭示出其生烃行为的差异性。利用GOR-IsotopeKinetics软件,推导了库车坳陷侏罗系煤、泥岩和三叠系湖相泥岩3类烃源岩的碳同位素动力学参数。上述参数的获取,为盆地模拟、烃源岩评价、生烃量计算及资源量预测提供了重要的基础地球化学数据。   相似文献   

The petrogenesis and implications of deformed late Caledonian–early Hercynian granites in the Wuyi area,South China          下载免费PDF全文

Xilin Zhao  Yang Jiang  Guangfu Xing  Minggang Yu  Kai Liu  Zhihong Chen  Shengyao Yu 《Island Arc》2017,26(5)

Precambrian basement rocks have been affected by Caledonian thermal metamorphism. Caledonian‐aged zircon grains from Precambrian basement rocks may have resulted from thermal metamorphism. However, Hercynian ages are rarely recorded. Zircon U–Pb Sensitive High Resolution Ion Microprobe (SHRIMP) dating reveals that zircon ages from the Huyan, Lingdou, and Pengkou granitic plutons can be divided into two groups: one group with ages of 398.9 ±5.3 Ma, 399 ±5 Ma, and 410.2 ±5.4 Ma; and a second group with ages of 354 ±11 Ma, 364.6 ±6.7 Ma, and 368 ±14 Ma. The group of zircon U–Pb ages dated at 410–400 Ma represent Caledonian magmatism, whereas the 368–354 Ma ages represent the age of deformation, which produced gneissosity. The three plutons share geochemical characteristics with S‐type granites and belong to the high‐K calc‐alkaline series of peraluminous rocks. They have (⁸⁷Sr/⁸⁶Sr)_i ratios of 0.710 45–0.724 68 and εNd(t) values of ?7.33 to ?10.74, with two‐stage Nd model ages (T_DM2) ranging from 1.84 Ga to 2.10 Ga. Magmatic zircon εHf(t) values range from ?3.79 to ?8.44, and have T_DMC ages of 1.65–1.93 Ga. The data suggest that these granites formed by partial melting of Paleoproterozoic to Mesoproterozoic continental crust. A collision occurred between the Wuyi and Minyue microcontinents within the Cathaysia Block and formed S‐type granite in the southwest Fujian province. The ca 360 Ma zircon U–Pb ages can represent a newly recognized period of deformation which coincided with the formation of the unified Cathaysia Block.  相似文献   

Cosmogenic 36Cl glacial chronologies of the Late Quaternary glaciers on Mount Geyikdağ in the Eastern Mediterranean     

《Quaternary Geochronology》2017

We report the timing of glaciations during the Late Quaternary in the central Taurus Mountains of Turkey in the Eastern Mediterranean. Forty moraine samples from three glacial valleys on Mount Geyikdağ (36.53°N, 32.10^°E, 2877 m), near the Eastern Mediterranean coast of Turkey, were dated with in-situ cosmogenic ³⁶Cl. These glacial valleys are located on the southern flank of the mountain and were filled with few km long glaciers that terminated at elevations of about 1750 m above sea level. Three glacial retreats/advances were determined in this study. During the Last Glacial Maximum (LGM), glaciers reached their maximum positions at 20.6 ± 0.6 ka ago (±1σ). This date is in accordance with the timing of local maximum ice extent, represented by piedmont glaciers in the northern side of the mountain. Glaciers started to retreat after the LGM and shortly stabilized or re-advanced two times before they completely vanished out. The first stage ended before 13.7 ± 0.8 ka ago during the Late-glacial. The last glaciation occurred during the Holocene and ended between 9.6 ± 1.4 ka and 5.9 ± 0.5 ka ago. Later, glaciers mostly vanished from the study area, but a few rock glaciers developed during the Late Holocene. Glacial chronologies of Mount Geyikdağ are mostly comparable with the globally observed advances elsewhere.  相似文献   

湖光岩玛珥湖春季浮游植物对溶解态氮的吸收   总被引：1，自引：1，他引：0  

张国维  李长玲  黄翔鹄  古滨河 《湖泊科学》2015,27(3):527-534

利用15N稳定同位素示踪技术,采用现场挂瓶培养的方法测定了湖光岩玛珥湖浮游植物群落对铵态氮、硝态氮和尿素态氮的吸收速率,研究了湖光岩玛珥湖浮游植物群落氮吸收及其吸收动力学特征.结果表明:湖光岩玛珥湖共检测到浮游植物7门54种(包括变种和变型),主要为蓝藻门、硅藻门和绿藻门种类,分别占浮游植物总量的44.68%、26.70%和19.21%,其中水华微囊藻(Microcystis flos-aquae)与铜绿微囊藻(Microcystis aeruginosa)为绝对优势种,优势度分别为0.39与0.28.湖光岩玛珥湖浮游植物群落对铵态氮的绝对吸收速率最高,分别是对硝态氮、尿素态氮绝对吸收速率的5.8和4.2倍,占3种溶解态氮总吸收量的73.3%.铵态氮、硝态氮和尿素态氮的相对优先指数分别为2.907、0.190和1.192,说明浮游植物群落优先吸收铵态氮,其次为尿素态氮,最后为硝态氮.铵态氮、硝态氮和尿素态氮的周转时间分别为3.72、57.03和9.07 h.湖光岩玛珥湖浮游植物对溶解态氮的吸收可用Michaelis-Menten酶动力学方程描述,最大比吸收速率表现为铵态氮尿素态氮硝态氮,亲和力表现为硝态氮铵态氮尿素态氮.湖光岩玛珥湖浮游植物群落对铵态氮具有较高的吸收潜力,并且对硝态氮具有一定的亲和力,具备利用硝态氮的能力.  相似文献   

Macroinvertebrate community structure and feeding interactions along a pollution gradient in Gilgel Gibe watershed,Ethiopia: Implications for biomonitoring     

《Limnologica》2017

Feeding interactions among functional feeding groups (FFGs) of macroinvertebrates are robust indicators of aquatic ecosystem interactions. They provide information regarding organic matter processing, habitat condition and trophic dynamics. In tropical rivers with pronounced wet and dry seasons, macroinvertebrate based ecological monitoring tools are explicitly focused on metrics and indices, while ignoring interactions of FFGs. Therefore, the objective of this study was to investigate the functional feeding type metrics, diversity indices and feeding interactions among FFGs of macroinvertebrates along the water pollution gradient in Gilgel Gibe watershed, Ethiopia. Water quality parameters and macroinvertebrate community attributes were assessed for samples collected from upstream sites (15 sites), urban-impacted stretches (12 sites) and wetland-affected river zones (7 sites) of the watershed during the rainy (July) and dry (February) seasons. To understand the effect of pollution on the feeding interactions, stable carbon and nitrogen isotopes were analyzed. Macroinvertebrate-based diversity indices and functional feeding type metric showed deterioration of ecological integrity at the urban-impacted sites and substantial recovery in the wetland-affected downstream sites. Omnivorous feeding behavior of macroinvertebrates was noted for the upstream sites, whereas clear trophic guilds of FFGs were suggested for the wetland-affected river zones by the stable isotope results. The results of pollution gradient analysis and feeding interactions among FFGs revealed that the urban-impacted sites showed weaker interactions when compared to upstream and wetland influenced sites. This affirms the potential importance of feeding interactions among FFGs of macroinvertebrates in water quality monitoring.  相似文献   

Continuous real‐time analysis of the isotopic composition of precipitation during tropical rain events: Insights into tropical convection          下载免费PDF全文

Shaoneng He  Nathalie F. Goodkin  Dominik Jackisch  Maria Rosabelle Ong  Dhrubajyoti Samanta 《水文研究》2018,32(11):1531-1545

To investigate stable isotopic variability of precipitation in Singapore, we continuously analysed the δ‐value of individual rain events from November 2014 to August 2017 using an online system composed of a diffusion sampler coupled to Cavity Ring‐Down Spectrometer. Over this period, the average value (δ¹⁸O_Avg), the lowest value (δ¹⁸O_Low), and the initial value (δ¹⁸O_Init) varied significantly, ranging from ?0.45 to ?15.54‰, ?0.9 to ?17.65‰, and 0 to ?13.13‰, respectively. All 3 values share similar variability, and events with low δ¹⁸O_Low and δ¹⁸O_Avg values have low δ¹⁸O_Init value. Individual events have limited intraevent variability in δ‐value (Δδ) with the majority having a Δδ below 4‰. Correlation of δ¹⁸O_Low and δ¹⁸O_Avg with δ¹⁸O_Init is much higher than that with Δδ, suggesting that convective activities prior to events have more control over δ‐value than on‐site convective activities. The d‐excess of events also varies considerably in response to the seasonal variation in moisture sources. A 2‐month running mean analysis of δ¹⁸O reveals clear seasonal and interannual variability. Seasonal variability is associated with the meridional movement of the Intertropical Convergence Zone and evolution of the Asian monsoon. El Niño–Southern Oscillation is a likely driver of interannual variability. During 2015–2016, the strongest El Niño year in recorded history, the majority of events have a δ¹⁸O value higher than the weighted average δ¹⁸O of daily precipitation. δ¹⁸O shows a positive correlation with outgoing longwave radiation in the western Pacific and the Asian monsoon region, and also with Oceanic Niño Index. During El Niño, the convection centre shifts eastward to the central/eastern Pacific, weakening convective activities in Southeast Asia. Our study shows that precipitation δ‐value contains information about El Niño–Southern Oscillation and the Intertropical Convergence Zone, which has a significant implication for the interpretation of water isotope data and understanding of hydrological processes in tropical regions.  相似文献   

Stable isotopes of pedogenic carbonates from the Somma–Vesuvius area,southern Italy,over the past 18 kyr: palaeoclimatic implications     

G. Zanchetta  M. Di Vito  A. E. Fallick  R. Sulpizio 《第四纪科学杂志》2000,15(8):813-824

Stable isotopes were measured in the carbonate and organic matter of palaeosols in the Somma–Vesuvius area, southern Italy in order to test whether they are suitable proxy records for climatic and ecological changes in this area during the past 18000 yr. The ages of the soils span from ca. 18 to ca. 3 kyr BP. Surprisingly, the Last Glacial to Holocene climate transition was not accompanied by significant change in δ¹⁸O of pedogenic carbonate. This could be explained by changes in evaporation rate and in isotope fractionation between water and precipitated carbonate with temperature, which counterbalanced the expected change in isotope composition of meteoric water. Because of the rise in temperature and humidity and the progressive increase in tree cover during the Holocene, the Holocene soil carbonates closely reflect the isotopic composition of meteoric water. A cooling of about 2°C after the Avellino eruption (3.8 ka) accounts for a sudden decrease of about 1‰ in δ¹⁸O of pedogenic carbonate recorded after this eruption. The δ¹³C values of organic matter and pedogenic carbonate covary, indicating an effective isotope equilibrium between the organic matter, as the source of CO₂, and the pedogenic carbonate. Carbon isotopes suggest prevailing C₃ vegetation and negligible mixing with volcanogenic or atmospheric CO₂. Copyright © 2000 John Wiley & Sons, Ltd.  相似文献   

江西相山酸性火山-侵入杂岩精确年代学与演化序列研究   总被引：7，自引：0，他引：7       下载免费PDF全文

郭福生  杨庆坤  谢财富  孟祥金  周万蓬  姜勇彪  张树明  吴志春 《地质科学》2015,(3):684-707

相山火山盆地主体岩石为一套由熔结凝灰岩、流纹英安岩、流纹英安斑岩、碎斑熔岩、粗斑花岗斑岩及似斑状花岗岩组成的酸性火山-侵入杂岩体, 构成了两个完整的喷发-溢流(侵出)-侵入的岩浆活动亚旋回。本文在野外地质调查的基础上, 采用SIMS、LA-ICP-MS技术对主要岩类进行了高精度的锆石U-Pb年代学研究, 并建立了火山-侵入杂岩体的演化序列。结果表明, 打鼓顶组熔结凝灰岩代表了相山火山-侵入活动的最早期产物, 其锆石U-Pb年龄为140.7±2.7 Ma、140.1±1.8 Ma和138.2±1.6 Ma, 第一亚旋回主体流纹英安岩的锆石U-Pb年龄135.0±1.8 Ma。鹅湖岭组熔结凝灰岩代表了火山-侵入活动的第二亚旋回的开始, 其U-Pb年龄为135.6±1.2 Ma, 第二亚旋回主体碎斑熔岩的锆石U-Pb年龄133.6±1.3 Ma, 沙洲单元的粗斑花岗斑岩和似斑状花岗岩属于该亚旋回最晚期的侵入岩, 其锆石U-Pb年龄代表了相山火山-侵入活动的结束时间(分别为133.4±1.2 Ma和133.9±1.1 Ma)。相山早白垩世火山-侵入活动延续时间较短, 整体上呈现一个连续的过程, 初始时间在141 Ma附近, 结束时间在132 Ma左右。概言之, 第一亚旋回(141~135 Ma)以形成熔结凝灰岩、流纹英安岩和流纹英安斑岩为主, 第二亚旋回(135~132 Ma)以熔结凝灰岩、碎斑熔岩、粗斑花岗斑岩和似斑状花岗岩为主。岩石地球化学和野外地质特征也与两个亚旋回火山-侵入岩浆活动相吻合。  相似文献