渤海湾表层沉积物元素地球化学分布特征与影响因素     

张连杰  朱龙海  张盼  赵博  王鹏 《海洋科学》2019,43(6):78-87

对取自渤海湾的307个表层沉积物进行了元素测试和粒度分析。渤海湾表层沉积物的常微量元素呈现4种组合:富集于粗粒沉积区的SiO_2、Na_2O亲碎屑元素组合;富集于细粒沉积区的以Al_2O_3和重金属元素为代表的亲黏土元素组合;与缺氧环境有关的MnO、V、TOC元素组合和与河流输入有关的陆源CaO、TiO_2元素组合。粒度粗细主导了渤海湾元素含量分布的整体格局;海域河流物源供应不同较大影响了渤海湾南部(富Na_2O、CaO和SiO_2)和北部(富Ba和P_2O_5)在元素含量上的差异;高流速潮流对海底的冲刷再分配导致曹妃甸南侧Sr、Ca元素的条带状富集异常;有机质在细粒沉积区的富集导致缺氧环境的形成和K_2O、Mn、V、自生黄铁矿的海洋自生化学沉积;人类活动导致以Pb为代表的重金属污染在河流入海口、港口及沿岸海域的元素分布异常;曹妃甸沙坝内侧的泻湖(海洋钙质生物沉积)与沙坝外侧水下岸坡(陆源碎屑沉积)的截然不同的物源,导致了独特地貌沉积环境下元素分布的局部差异。  相似文献   

Method‐dependent influence of environmental variables on reef fish assemblages when comparing trap and video surveys     

Nathan R. Geraldi  Nathan M. Bacheler  G. Todd Kellison 《Marine Ecology》2019,40(1)

Despite substantial survey effort and a large body of literature on abiotic and biotic factors in temperate reef ecosystems, knowledge of the complex and interactive effects of environmental variables on those communities is limited. Various survey methods have been developed to study environmental predictors of biodiversity, but there remains a gap in our understanding of how survey results are influenced by environmental factors. Here, we surveyed the fish assemblage associated with southeastern U.S. temperate marine reefs with simultaneous, paired trap, and camera gears throughout a ~50,000 km² area during 2011–2013 and assessed the influence of environmental variables on the trap‐ and video‐surveyed assemblages. Predictor variables in the multivariate general linear models included depth, temperature, month, year, location, substrate relief, percent sessile biota, biota type, and turbidity. Depth and latitude had the greatest influence on the fish assemblage for both gears. The influence of habitat variables differed between methods and percent biota explained more variation in the fish assemblage when assessed by traps, while substrate relief and biota type explained more variation in the fish assemblage when assessed by video. In general, habitat complexity was positively related to the abundance of fishes in the video survey, but there was a negative relationship in the trap survey. Differences between gears were species‐specific and the influences of environmental variables were similar for some species such as Haemulon plumierii and Hyporthodus niveatus. The methods presented here can be used to assess method‐dependent differences in fish assemblages, which is a necessary precursor to assess the effect of environmental variables on the accuracy of surveys.  相似文献   

西藏类乌齐地区含镍碳酸岩的发现与地质意义     

周新  冯德新  樊炳良  余佳树  嘎桑顿珠  易金龙 《矿物学报》2020,(2):109-115

野外调查发现西藏类乌齐地区分布着众多的含镍碳酸岩体,呈十几米至几百米不等的岩株出露。岩体与超基性岩之间具明显的港湾状、枝状侵入接触、岩石不具层理、岩石表现出细粒结晶等粒结构、岩体内见超基性岩捕掳体等特征均表明其为火成碳酸岩岩体。在成分上以菱镁矿为主,岩石中MgO的含量为27.16%~31.75%,为镁质碳酸岩。岩石稀土元素配分曲线呈平缓右倾的轻稀土富集型,轻重稀土元素分馏现象明显,具有明显的Eu正异常和弱的Ce负异常;微量元素显示Rb、Th、Nb、Hf元素相对富集,K、U、Ti元素相对亏损。含镍碳酸岩可能是富CO2的深部流体在中下地壳对超基性岩交代的结果,具备寻找硫化镍矿床的有利条件。  相似文献   

甘青地区马家窑文化彩陶贸易及其动力探讨     

崔一付  杨谊时  张山佳  李国林  李冀源  陈国科 《第四纪研究》2020,(2):538-546

马家窑文化是甘青地区仰韶文化晚期阶段一个重要的文化遗存类型,其以精美的彩陶闻名于世,对于马家窑文化彩陶的交流传播研究受到了学术界的广泛关注.本文运用X-荧光光谱分析法对甘青地区5个典型马家窑文化早期阶段遗址出土的92件彩陶陶片样品和各遗址附近采集的42份红粘土及黄土样品进行化学元素组成分析,追溯彩陶的产源地及贸易.同时基于陶器的起源传播理论,收集整理马家窑文化区遗址出土的粟(Setaria italica)、黍(Panicum miliaceum)农作物以及动物骨骼遗存鉴定资料,探讨马家窑彩陶贸易的动力.Ti/Al-Na/K和主成分分析结果显示宗日文化区宗日遗址的马家窑文化彩陶元素组成特征和马家窑文化主体区域的彩陶一致,表明宗日遗址马家窑类型彩陶是从马家窑文化主体区域贸易而来;马家窑文化彩陶的传播和该地区粟黍农作物的交流传播具有时空一致性,粟黍农业人群沿黄河上游谷地向共和盆地的扩散带来了新的文化元素;宗日文化区和马家窑文化核心区生业模式的差异带来了跨区域间文化交流的动力,这也可能是马家窑文化彩陶贸易的动力.  相似文献   

浙南花岗岩残积土物质结构及工程地质特性研究     

孙强  张泰丽  伍剑波  王赫生 《地质论评》2020,66(S1):163-166

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Dissolved organic matter in surface runoff in the Loess Plateau of China: The role of rainfall events and land-use     

Zhongwu Li  Hao Peng  Binggeng Xie  Chun Liu  Xiaodong Nie  Danyang Wang  Mei Huang  Haibing Xiao  Lin Shi  Xuqin Zhang  Jieyu Jiang 《水文研究》2020,34(6):1446-1459

Exploring the chemical characterization of dissolved organic matter (DOM) is important for understanding the fate of laterally transported organic matter in watersheds. We hypothesized that differences in water-extractable organic matter (WEOM) in soils of varying land uses and rainfall events may significantly affect the quality and the quantity of stream DOM. To test our hypotheses, characteristics of rainfall-runoff DOM and WEOM of source materials (topsoil from different land uses and gullies, as well as typical vegetation) were investigated at two adjacent catchments in the Loess Plateau of China, using ultraviolet–visible absorbance and excitation emission matrix fluorescence with parallel factor analysis (PARAFAC). Results indicated that land-use types may significantly affect the chemical composition of soil WEOM, including its aromaticity, molecular weight, and degree of humification. The PARAFAC analysis demonstrated that the soils and stream water were dominated by terrestrial/allochthonous humic-like substances and microbial transformable humic-like fluorophores. Shifts in the fluorescence properties of stream DOM suggested a pronounced change in the relative proportion of allochthonous versus autochthonous material under different rainfall patterns and land uses. For example, high proportions of forestland could provide more allochthonous DOM input. This study highlights the relevance of soils and hydrological dynamics on the composition and fluxes of DOM issuing from watersheds. The composition of DOM in soils was influenced by land-use type. Precipitation patterns influenced the proportion of terrestrial versus microbial origins of DOM in surface runoff. Contributions of allochthonous, terrestrially derived DOM inputs were highest from forested landscapes.  相似文献   

Barium Isotopic Compositions in Thirty‐Four Geological Reference Materials Analysed by MC‐ICP‐MS     

Ya‐Jun An  Xin Li  Zhao‐Feng Zhang 《Geostandards and Geoanalytical Research》2020,44(1):183-199

Measurement of Ba isotope ratios of widely available reference materials is required for interlaboratory comparison of data. Here, we present new Ba isotope data for thirty‐four geological reference materials, including silicates, carbonates, river/marine sediments and soils. These reference materials (RMs) cover a wide range of compositions, with Ba mass fractions ranging from 6.4 to 1900 µg g^?1, SiO₂ from 0.62% to 90.36% m/m and MgO from 0.08% to 41.03% m/m. Accuracy and precision of our data were assessed by the analyses of duplicate samples and USGS rock RMs. Barium isotopic compositions for all RMs were in agreement with each other within uncertainty. The variation of δ^138/134Ba in these RMs was up to 0.7‰. The shale reference sample, affected by a high degree of chemical weathering, had the highest δ^138/134Ba (0.37 ± 0.03‰), while the stream sediment obtained from a tributary draining carbonate rocks was characterised by the lowest δ^138/134Ba (?0.30 ± 0.05‰). Geochemical RMs play a fundamental role in the high‐precision and accurate determination of Ba isotopic compositions for natural samples with similar matrices. Analyses of these RMs could provide universal comparability for Ba isotope data and enable assessment of accuracy for interlaboratory data.  相似文献   

印度尼西亚北苏拉威西蓝碧海峡浮游动物种类组成及分布   总被引：1，自引：0，他引：1  

王彦国  陈小银  邢炳鹏  孙柔鑫  FITRIA Nurul  项鹏  王春光  林茂 《海洋学报(英文版)》2018,37(12):35-44

Based on oceanographic survey data in June 2012 in the Lembeh Strait, the zooplankton ecological characteristics such as species composition, individual abundance, dominant species and distribution were analyzed. The results showed that 183 species(including 4 sp.) had been recognized, most of them belonged to copepoda.Cnidaria followed with 43 species(including 1 sp.) were identified. The average abundance of zooplankton was(150.47±58.91) ind./m~3. As to the horizontal distribution, the abundance of the zooplankton was higher in the southern waters than in the northern waters. The dominant species in the study area were Lensia subtiloides,Sagitta enflata, Lucifer intermedius, Oikopleura rufescens, Diphyes chamissoni, Creseis acicula, Subeucalanus subcrassus, Temora discaudata, Aglaura hemistoma, Doliolum denticulatum, Canthocalanus pauper, Oikopleura longicauda and Nanomia bijuga. Zooplankton biodiversity indexes were higher in study area than previous study in the other regions. The findings from this study provide important baseline information for future research and monitoring programs.  相似文献   

Mesozooplankton spatial distribution and community structure in the South Adriatic Sea during two winters (2015, 2016)          下载免费PDF全文

Marijana Hure  Hrvoje Mihanović  Davor Lučić  Zrinka Ljubešić  Petar Kružić 《Marine Ecology》2018,39(1)

Whereas the data on mesozooplankton in the epipelagic offshore Mediterranean Sea are extensive, less information is available about plankton in the deeper layers. The present study aims to describe the vertical and horizontal structure and distribution of mesozooplankton species and their associations down to 1,200 m in the water of the Southern Adriatic Sea. Zooplankton were sampled using a Nansen net of 200‐μm mesh size during two cruises in the winters of 2015 and 2016, extending from the coast to the open sea. In total, 203 zooplankton taxa were identified. The community was dominated by copepods, representing between 67% and 91% of the total abundance. The highest total densities were recorded in the upper layers where a high proportion (up to 36%) of appendicularians was also observed in the first sampled year. Five groups of samples were determined based on their community structure. In 2015 communities were distinct between the 0 and 50 m layer and the underlying one (50–100 m), whereas in 2016 epipelagic waters were inhabited by a more uniform mesozooplankton community. The mesopelagic and deep‐water fauna, especially copepods, showed a relatively stable composition in both sampling years Overall, our study confirms the oligotrophic character of the Southern Adriatic, with occasional density outbreaks of appendicularians under favourable conditions.  相似文献   

Zircon U–Pb ages and Hf isotope compositions of migmatites from the North Qinling terrane and their geological implications     

Q. Liu  Y.‐B. Wu  H. Wang  S. Gao  Z.‐W. Qin  X.‐C. Liu  S.‐H. Yang  H.‐J. Gong 《Journal of Metamorphic Geology》2014,32(2):177-193

Migmatites are predominant in the North Qinling (NQ) orogen, but their formation ages are poorly constrained. This paper presents a combined study of cathodoluminescence imaging, U–Pb age, trace element and Hf isotopes of zircon in migmatites from the NQ unit. In the migmatites, most zircon grains occur as new, homogeneous crystals, while some are present as overgrowth rims around inherited cores. Morphological and trace element features suggest that the zircon crystals are metamorphic and formed during partial melting. The inherited cores have oscillatory zoning and yield U–Pb ages of c. 900 Ma, representing their protolith ages. The early Neoproterozoic protoliths probably formed in an active continental margin, being a response to the assembly of the supercontinent Rodinia. The migmatite zircon yields Hf model ages of 1911 ± 20 to 990 ± 22 Ma, indicating that the protoliths were derived from reworking of Palaeoproterozoic to Neoproterozoic crustal materials. The anatexis zircon yields formation ages ranging from 455 ± 5 to 420 ± 4 Ma, with a peak at c. 435 Ma. Combined with previous results, we suggest that the migmatization of the NQ terrane occurred at c. 455–400 Ma. The migmatization was c. 50 Ma later than the c. 490 Ma ultra‐high‐P (UHP) metamorphism, indicating that they occurred in two independent tectonic events. By contrast, the migmatization was coeval with the granulite facies metamorphism and the granitic magmatism in the NQ unit, which collectively argue for their formation due to the northward subduction of the Shangdan Ocean. UHP rocks were distributed mainly along the northern margin and occasionally in the inner part of the NQ unit, indicating that they were exhumed along the northern edge and detached from the basement by the subsequent migmatization process.  相似文献