Application of stable isotope techniques in studies of carbon and nitrogen biogeochemical cycles of ecosystem

Stable isotope techniques have been proved useful as tools for studying the carbon (C) and nitrogen (N) biogeochemical cycles of ecosystem. This paper firstly introduced the basic principles and the distribution characteristics of stable isotope, then reviewed the recent advances and applications of stable isotope in the C and N biogeochemical cycles of ecosystem. By applying the 13 C natural abundance technique, ecologists are able to understand the photosynthetic path and CO 2 fixation of plants, the CO 2 exchange and C balance status of ecosystem, the composition, distribution and turnover of soil organic C and the sources of organic matter in food webs, while by using the 13 C labeled technique, the effects of elevated CO 2 on the C processes of ecosystem and the sources and fate of organic matter in ecosystem can be revealed in detail. Differently, by applying the 15 N natural abundance technique, ecologists are able to analyze the biological N 2 -fixation, the N sources of ecosystem, the N transformation processes of ecosystem and the N trophic status in food webs, while by using the 15 N labeled technique, the sources, transformation and fate of N in ecosystem and the effects of N input on the ecosystem can be investigated in depth. The applications of both C and N isotope natural abundance and labeled techniques, combined with the elemental, other isotope ( 34 S) and molecular biomarker information, will be more propitious to the investigation of C and N cycle mechanisms. Finally, this paper concluded the problems existed in current researches, and put forward the perspective of stable isotope techniques in the studies on C and N biogeochemical cycles of ecosystem in the future.     

Stable isotopes distribution in core Ck6 and variations of paleoclimate over Qarhan Lake region in Qaidam Basin, China

Depositing ages of sediment in Core Ck6 of Qarhan Lake were dertermined by¹⁴C,²³⁰Th and geomagnetic polarity methods. Results of analyses of stable isotopes composition in carbonate and organic matter were used to set up a model of fluctuating paleoclimate (since 750 ka B. P.) consisting of 11 warm and humid stages and 10 dry and cold stages.     

STABLE ISOTOPES DISTRIBUTION IN CORE Ck6 AND VARIATIONS OF PALEOCLIMATE OVER QARHAN LAKE REGION IN QAIDAN BASIN, CHINA

ImODareNThelast3Oycars'~tilicproductinnofsalts,andnawh,andexpIorationofsaltlakes,haveyboedmuCinfonnationonQarhanInke.Thereisliteraturedetailingthelakebpaleo-dhate,paboenvbonment,paboerelogy,evolution,etC-since5OkaB.P.(ZhengPenShinCtal.,l993,ChenKereoetal.,l986;HuangQiCtal.,l98l),butfewonthebefore5OkaB-P-eventS.CoreCk6thattheFirsttheloghalExplorationTeamoftheQinghaibologicalBu-rmudrilledat9lOmdePthinQarhanLakeyallasetofcontinuouslylacustrinetali-rnentdataveryvaluableforstudyofpabo…     

凡纳滨对虾不同生长阶段食物组成结构的研究

利用稳定同位素碳比率δ13C作为天然示踪物,对高位养殖池生态系统中人工饲料和天然饵料提供的能源物质对养殖凡纳滨对虾生长的贡献比率进行研究。结果表明:虾体的δ13C值受食物δ13C值的影响,由于其摄食饵料的δ13C值逐渐减小,虾体的δ13C值也逐渐降低,逐渐接近于最后人工饲料的δ13C值,试验虾体的δ13C值由养殖开始时的-19.52‰±0.09‰变为实验结束时的-21.74‰±0.17‰;对虾的食性在10d左右时发生转变,34d左右时人工饲料和浮游动物对虾体的能量贡献基本相同,养殖结束时对虾生长能量的97.29%±0.98%来源于人工饲料。     

Stable Isotope Signatures and Moisture Transport of a Typical Heavy Precipitation Case in the Southern Tianshan Mountains

Stable oxygen isotopes in precipitation contain meaningful environmental information on a synoptic scale and can be applied to diagnose hydrometeorological processes.A series of rainstorms occurred at the southern Tianshan Mountains during the period from May to June 2013,and the event-based precipitation was sampled along the mountain range from west to east.Based on δ18 O values in precipitation samples as well as the corresponding meteorological parameters,the moisture transport paths during the sampling period were identified.In late-May(stage 1),isotopes in precipitation collected generally showed a depleting trend.In mid-June(stage 2),there was no coherent trend of isotopes in precipitation for these stations,and only isotope values in Aksu showed a continually depleting trend.Checking other meteorological proxies during the sampling period,the event-based precipitation isotopes sensitively reflected the moisture process.In central Asia,both the westerly and monsoon moisture can be delivered to cause extreme precipitation events,and the isotopic information provides an alternative tool to investigate the atmospheric processes.     

A METHOD TO ESTIMATE PALEOTEMPERATURE FROM ENVIRONMENTAL PROXIES IN LAKE SEDIMENTS——A STUDY ON ZOIGE BASIN IN EASTERN TIBETAN PLATEAU, CHINA

Seeking for an effective method to probe further the relation among Tibetan Plateau, climatic events, and natural environmental changes in the Zoige Basin, we proposed a physical model for the reconstruction of climate and environment and a preliminary application was conducted on the 45 m (about 200 ka BP), upper part of Core RM (310 m long) drilled in the Zoige Basin (33°57’N, 102°21’E), on the eastern Tibetan Plateau. The results showed that: a) in the Zoige region, the maximum temperature in the period equivalent to Stage 7 in the deep-sea stable oxygen record was 2.7°C higher than that at present; b) Stage 6 temperature was 4.3°C lower than that at present; c) Stage 5 peak temperature was 5.2°C higher that that at present; d) Stage 4 average temperature should have been 2–3°C lower than that at present; and e) Stage 3 temperature differences within the period were more than 4°C. It was found that during Stage 6 (140–160 ka BP) the environment in the Zoige Basin was extraordinary, representing a transition period from warm-dry and cold-wet to warm-wet and cold-dry environmental conditions due to the uplift that occurred on the Tibetan Plateau at this period. Project 49803001 supported by NSFC and also funded by National and CAS Tibet Research Project (G1998040800).     

A METHOD TO ESTIMATE PALEOTEMPERATURE FROM ENVIRONMENTAL PROXIES IN LAKE SEDIMENTSDISSOLVED AND PARTICULATE ORGANIC CARBON IN YANTAI SISHILI BAY AQUICULTURE WATERS——A STUDY ON ZOIGE BASIN IN EASTERN TIBETAN PLATEAU,CHINA

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Compositions of δ18O and δ13C in various carbonates of core RM in the Zoigê Basin and climatic significance

The hole RM, the deepest one fully obtained core in the Qinghai-Xizang Plateau, situated in the depositional center of the Zoige Basin (33°57′N; 102° 21′E) in the northeastern Qinghai-Xizang Plateau with a depth of 310.46 m. From ¹⁴C dating and paleomagnetic stratigraphic study, the core RM can date back to 900 ka B.P.. In this paper we analyzed the compositions of δ¹⁸O and δ¹³C in various carbonates can date (snail, obstrode, chemical carbonate) in core RM and discussed preferably the paleoclimatic record by the proxies of δ¹⁸O and δ¹³C of chemical carbonate (authicarbonate) from core RM in the past 140 ka. The results showed that the values of δ¹⁸O in various carbonates are generally identical, and the values of δ¹³C in it are inconsistent, while there exist better relativity. The studies also demonstrated that there was a negative correlation between δ¹⁸O and δ¹³C of authicarbonate in core RM in the past 140 ka, showing that the changes of δ¹⁸O values were mainly relative to the water temperature. According to above, the climatic evolutionary sequence were rebuilt in the past 140 ka in the region.     

不同条件下波吉卵囊藻对氨氮的吸收速率

在实验室条件下模拟多种氮源共存的虾池水环境,利用稳定同位素示踪剂,研究温度、光照、盐度、pH、藻浓度对波吉卵囊藻氨氮吸收速率的影响。结果表明:温度、光照和藻浓度对波吉卵囊藻氨氮吸收速率影响极显著(P<0.01)。当温度为20℃,照度为4 500 lx,藻浓度为5.5×105/mL,波吉卵囊藻对氨氮均有最大的吸收速率,分别为1.114、1.400、1.482μg g-1 h-1。单因素方差分析得出波吉卵囊藻吸收氨氮的最优组合为:温度20℃,照度4 500lx,盐度15,pH 7.5,藻浓度5.5×105/mL。可通过对环境因子的调控,提高波吉卵囊藻对水体中氨氮的吸收速率。     

陕西潼峪金矿成因问题商榷

基于多元论的观点,讨论了潼峪金矿含金石英脉的成因。燕山期小秦岭处于大陆边缘活化带,断裂、岩浆活动十分强烈,形成了高热流环境。燕山期花岗岩侵位浅,裂隙系统提供了良好的循环通道,加上丰富的地下水条件,在花岗岩热力作用下,受到加热的下降雨水和来自花岗岩的高温富碱流体是围岩中的金和有关成矿元素活化迁移的有效介质,在中深条件下形成了石英脉型金矿,在浅成条件下形成了蚀变岩型金矿。     

Food sources of the Manila clam Ruditapes philippinarum in intertidal areas: evidence from stable isotope analysis

Based on stable isotope analysis, we characterized the dietary regime of the Manila clam Ruditapes philippinarum inhabiting intertidal areas along the Liaodong Peninsula, Northern China. Samples, including particulate organic matter (POM; n =30), benthic microalgae (BMI; n =30) and R. philippinarum (n =60), were collected from six sampling sites displaying the same ecological conditions. Of the two primary food sources, POM was more depleted in δ ¹³C (?20.61‰ to ?22.89‰) than BMI was (?13.90‰ to ?16.66‰). With respect to ¹⁵N, BMI was more enriched (2.90‰ to 4.07‰) than POM was (4.13‰ to 5.12‰). The δ ¹³C values of R. philippinarum ranged from ?18.78‰ to ?19.35‰ and the δ ¹⁵N values from 7.96‰ to 8.63‰, which were intermediate between the POM and BMI values. In a two-source isotope mixing model, we estimated the relative contributions of POM and BMI to the diet of R. philippinarum to be 74.2% and 25.8%, respectively. We conclude that R. philippinarum feeds mainly on POM, and BMI is also an important supplemental food source in intertidal areas.     

Trophic ecology of sharks in the mid-east Pacific ocean inferred from stable isotopes

As apex predators, sharks are of ecological and conservation importance in marine ecosystems. In this study, trophic positions of sharks were estimated using stable isotope ratios of carbon and nitrogen for five representative species caught by the Chinese longline fleet in the mid-east Pacific, i.e., the blue shark(Prionace glauca), the bigeye thresher shark(Alopias superciliosus), the silky shark(Carcharhinus falciformis), the scalloped hammerhead(Sphyrna lewini), and the oceanic whitetip shark(Carcharhinus longimanus). Of these species, oceanic whitetip shark has the lowest trophic level and mean δ15N value(3.9 and 14.93‰± 0.84‰), whereas bigeye thresher shark has the highest level/values(4.5 and 17.02‰± 1.21‰, respectively). The bigeye thresher shark has significantly higher δ15N value than other shark species, indicating its higher trophic position. The blue shark and oceanic whitetip shark has significantly higher δ13C values than bigeye thresher shark, silky shark and scalloped hammerhead, possibly due to different diets and/or living habitats. The stable isotope data and stomach content data are highly consistent, suggesting that stable isotope analysis supplements traditional feeding ecology study of sharks, and thus contributes to understanding their trophic linkage.     

Seasonal changes in food uptake by the sea cucumber Apostichopus japonicus in a farm pond: Evidence from C and N stable isotopes

This study investigated the seasonal changes in carbon (C) and nitrogen (N) stable isotope values of several typical food sources of Apostichopus japonicus in a farm pond, including particulate organic matter (POM), macroalgae, benthic microalgae and animals such as nematode and copepod. The stable isotope technique was used to quantify relative contributions of various sources to the food uptake by A. japonicus. The results showed that significant changes occurred in the C and N stable isotope values of sea cucumber food sources due to the seasonality of micro-or macroalgae prosperity and the fluctuation of environmental conditions. The sea cucumber A. japonicus exhibited corresponding alterations in feeding strategy in response to the changes in food conditions. Calculation with a stable isotope mixing model showed that macroalgae was the principal food source for A. japonicus throughout the 1-yr investigation, with the relative contribution averaging 28.1% - 63.2%. The relative contributions of other food sources such as copepod and nematode, POM, benthic microalgae to the total food uptake by sea cucumber averaged 22.6% - 39.1%, 6.3% - 22.2%, 2.8% - 6.5%, and 2.8% - 4.2%, respectively. Together these results indicated that the seasonal changes in food sources led to the obvious temporal differences in the relative contribution of various food sources utilized by A. japonicus. Such findings provide the basic scientific information for improving the aquaculture techniques of A. japonicus, particularly for optimizing the food environment of A. japonicus culture in farm ponds.     

A Study on the Contribution of Different Food Sources to Shrimp Growth in an Intensive Fenneropenaeus chinensis Pond

Stable isotope methods can be used to determine the food sources and prey items of aquatic organisms accurately andreliably.This study examined the relative contribution of artificial foods (the formulated feed and Artemia) and natural foods toshrimp growth in an intensive Fenneropenaeus chinensis pond by using carbon and nitrogen stable isotopes.The results showed that the nutrition utilization efficiency of the harvested shrimp was low,only 33.18% of feed nitrogen and 21.73% of feed carbon beingconverted to shrimp flesh.Our stable isotope results showed that the shrimp obtained nutrition for maximum growth from artificialfoods,whose contribution was 93.5%,with the remaining attributed to the natural foods.However,there was 0.94 t harvested shrimpderived from natural foods (the rest of 13.56t harvested shrimp derived from artificial foods) in lha intensive pond with a shrimpproduction of 14.50 tha-1.Therefore,unit area shrimp production can be increased by increasing the contribution proportion of natu-ral foods in intensive shrimp farming.     

A Study on the contribution of different food sources to shrimp growth in an intensive <Emphasis Type="Italic">Fenneropenaeus chinensis</Emphasis> pond

Stable isotope methods can be used to determine the food sources and prey items of aquatic organisms accurately and reliably. This study examined the relative contribution of artificial foods (the formulated feed and Artemia) and natural foods to shrimp growth in an intensive Fenneropenaeus chinensis pond by using carbon and nitrogen stable isotopes. The results showed that the nutrition utilization efficiency of the harvested shrimp was low, only 33.18% of feed nitrogen and 21.73% of feed carbon being converted to shrimp flesh. Our stable isotope results showed that the shrimp obtained nutrition for maximum growth from artificial foods, whose contribution was 93.5%, with the remaining attributed to the natural foods. However, there was 0.94 t harvested shrimp derived from natural foods (the rest of 13.56 t harvested shrimp derived from artificial foods) in 1ha intensive pond with a shrimp production of 14.50 t ha⁻¹. Therefore, unit area shrimp production can be increased by increasing the contribution proportion of natural foods in intensive shrimp farming.     

Geochemical characteristics of stable isotopes from hydrothermal chimneys in the Mariana Trough, West Pacific Ocean

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Ontogenetic changes in isotopic signatures of an omnivorous fish Cultrichthys erythropterus in East Lake Taihu,China

The relationship between body size and stable isotopic signatures of the omnivorous Redfin Culter(C ultrichthys erythropterus),commonly found in East Lake Taihu,was investigated. Previous analyses of C. erythropterus stomach contents have shown that this species undergoes a diet switch from being predominantly zooplanktivorous to piscivorous during its life history. This was confirmed by stable carbon isotopic signature(δ 13 C) in this study,in which δ 13 C was positively correlated with both standard length and weight. The importance of littoral-benthic resources in supporting C. erythropterus during its lifespan was also demonstrated using a two-source mixing model,the results of which showed a significant increasing trend in the contribution of littoral-benthic energy. However,the stable nitrogen isotopic signature(δ 15N) exhibited an unusual pattern compared with previous studies. The δ 15 N of C. erythropterus showed no relationship with body size,even though dietary changes were observed. This indicated that δ 15 N alone cannot fully reflect a diet shift in a species and possible variability in isotopic signatures over its life history. This should be considered when using stable isotopic signatures to investigate intra-specific variations and the timing of life-history events,such as estimating the trophic positions of fish species.     

Trophic ecology of small yellow croaker (Larimichthys polyactis Bleeker): stable carbon and nitrogen isotope evidence

The trophic ecology of the small yellow croaker (Larimichthys polyactis) was studied using stable isotope analyses. Samples were collected from July to September 2009 and 34 individuals from eight sites were examined for stable carbon and nitrogen isotopes. Stable carbon isotope ratios (δ13C) ranged from -20.67 to -15.43, while stable nitrogen isotope ratios (δ15N) ranged 9.18-12.23. The relationship between δ13C and δ15N suggested high resource partitioning in the sampling area. Significant differences in stable isotope values among the eight sampling sites may be linked to environmental diversities involving various physical processes (such as ocean current, wind and tide) and different carbon sources. Furthermore, the stable isotope ratios may also explain the ontogenetic variability in diet and feeding, because δ13C and δ15N varied significantly with increasing body size. The findings are consistent with other studies on diet analyses in small yellow croaker. It was also demonstrated that stable isotope analysis could be used to estimate the trophic characters of small yellow croaker in feeding patterns and migrating habits.     

内蒙古金厂沟梁金矿床成矿流体特征及稳定同位素研究

对金厂沟梁金矿床含金石英脉中流体包裹体进行了岩相学、显微测温、单个包裹体的激光拉曼测试以及O和S同位素组成等方面研究。结果表明,成矿流体气相成分主要为H2 O,属H2 O-NaCl体系,包裹体均一温度为148.7℃～352℃,盐度[ w （ NaCl ）/％]为1.05％～5.99％。δ18 O值为-1.1‰～3.0‰,说明成矿流体继承了变质流体的特征,仍以岩浆水和后期大气降水为主;δ34 SV-CDT组成为0.6‰～4.3‰,平均值0.817‰,极差为3.1‰,表明成矿流体中的硫主要来自于幔源,其次为围岩。综合分析认为,金厂沟梁金矿床是在燕山晚期太平洋板块俯冲导致岩石圈的快速减薄、拆沉的拉张环境下形成的浅成造山型金矿。