Compound-specific isotopes of fatty acids as indicators of trophic interactions in the East China Sea ecosystem

The composition and compound-specific isotopes of fatty acids were studied within food webs in the East China Sea.Lipid-normalized stable carbon isotopes of total organic carbon had a good correlation with trophic level.Variations in fatty acid compositions among different species were observed but were unclear.Different dietary structures could be traced from molecular isotopes of selected fatty acids in the Shiba shrimp(Matapenaeus joyneri),the coastal mud shrimp(Solenocera crassicomis) and the northern Maoxia shrimp(Acetes chinensis).Both M.joyneri and S.crassicomis are mainly benthos feeders,while A.chinensis is a pelagic species,although they have a similar fatty acid composition.There was a good correlation for isotopes of arachidonic acid(C20:4n6;ARA) and docosahexaenoic acid(C22:6n3;DHA)among pelagic species from higher trophic levels.The isotopic compositions of DHA in benthic species were more negative than those of pelagic species at the same trophic level.The fact that the diet of benthic species contains more degraded items,the carbon isotopes of which are derived from a large biochemical fraction,may be the reason for this variation.A comparative study of benthic and pelagic species demonstrated the different carbon sources in potential food items and the presence of a more complex system at the watersediment interface.

Crustal Composition of China Continent Constrained from Heat Flow Data and Helium Isotope Ratio of Underground Fluid

Based on conservation of energy principle and heat flow data in China continent, the upper limit of 1.3 μW/m3 heat production is obtained for continental crust in China. Furthermore, using the data of heat flow and helium isotope ratio of underground fluid, the heat productions of different tectonic units in China continent are estimated in range of 0.58-1.12 μW/m3 with a median of 0.85 μW/m3. Accordingly, the contents of U, Th and K20 in China crust are in ranges of 0.83-1.76 μg/g, 3.16-6.69 μg/g, and 1.0%-2.12%, respectively. These results indicate that the abundance of radioactive elements in the crust of China continent is much higher than that of Archean crust; and this fact implies China＇s continental crust is much evolved in chemical composition. Meanwhile, significant lateral variation of crustal composition is also exhibited among different tectonic units in China continent. The crust of eastern China is much enriched in incompatible elements such as U, Th and K than that of western China; and the crust of orogenic belts is more enriched than that of platform regions. It can also be inferred that the crusts of eastern China and orogenic belts are much felsic than those of western China and platform regions, respectively, derived from the positive correlation between the heat production and SiO2 content of bulk crust. This deduction is consistent with the results derived from the crustal seismic velocity data in China. According to the facts of the lower seismic velocity of China than the average value of global crust, and the higher heat production of China continent compared with global crust composition models published by previous studies, it is deduced that the average composition models of global continent crust by Rudnick and Fountain （1995）, Rudnick and Gao （2003）, Weaver and Tarney （1984）, Shaw et al. （1986）, and Wedepohl （1995） overestimate the abundance of incompatible elements such as U, Th and K of continental crust.

Multi-collector ICP-MS Analysis of Pb Isotope Ratios in Rocks: Data, Procedure and Caution

The authors measured Pb isotope compositions of seven USGS rock referencestandards, i.e. AGV-1, AGV-2, BHVO-1, BHVO-2, BCR-2, BIR-1/1 and W-2, together with NBS 981 using amicromass isoprobe multi-collector inductively-coupled plasma mass spectrometer (MC-ICP-MS) at theUniversity of Queensland. ^(203)Tl-^(205)Tl isotopes were used as an internal standard to correctfor mass-dependant isotopic fractionation. The results for both NBS 981 and USGS rock standardsAGV-1 and BHVO-1 are comparable to or better than double- and triple-spike TIMS (thermal ionizationmass spectrometry) data in precision. The data for BHVO-2 and, to a lesser extent, AGV-2 and BCR-2are reproducibly higher for ^(206)Pb/^(204)Pb, ^(207)Pb/^(204)Pb and ^(208)Pb/^(204)Pb thandouble-spike TIMS data in the literature. The authors also obtained the Pb isotope data for BIR- 1/1and W-2, which may be used as reference values in future studies. It is found that linearcorrection for Pb isotopic fractionation is adequate with the results identical to those correctedfollowing an exponential law or a power law. Precise ^(207)Pb/^(206)Pb, ^(208)Pb/^(206)Pb and^(208)Pb/^(207)Pb ratios can be acquired for sample solutions with Pb>=1 ppb. However, Pb isotoperatios involving ^(204)Pb (i.e., ^(206)Pb/^(204)Pb, ^(207)Pb/^(204)Pb and ^(208)Pb/^(204)Pb) arereliable for solutions with Pb>=40 ppb. The errors for Pb isotope ratio analysis using the MC-ICP-MSare dominated by errors in the analysis of ^(204)Pb, which is commonly ascribed to the difficultyand imprecise correction for a ^(204)Hg isobaric interference. It is found however that the majorerrors on ^(204)Pb come from the tailings of mass ^(203)Tl and mass ^(205)Tl These mass tailingslead to over-subtraction of the baseline for ^(204)Pb, which is measured at +-0.5 amu on both sidesof mass-204 (i.e., at amu 203.5 and 204.5 respectively). Such errors are insignificant for Pb-richsample solutions (i.e., high Pb/Tl ratios), but can be severe for low-Pb sample solutions whenover-'spiked' with Tl. Experiments in this study suggest that a minimum concentration ratio ofPb/Tl>5 in Tl-'spiked' solutions be required to ensure reliable ^(206)Pb/^(204)Pb, ^(207)Pb/^(204)Pband ^(208)Pb/^(204)Pb isotopic ratios. The tailings of ^(203)Tl and ^(205)Tl can also lead toover-subtraction of baselines for ^(202)Hg (at amu 202.5) and ^(206)Pb (at amu 205.5). Therefore,the elegance of using ^(203)Tl and ^(205)Tl isotopes for mass fractionation correction becomes asevere problem in low-Pb rock solution-caution is required. Alternative internal standards for massfractionation correction may be considered. Of course, significant instrumental refinement inabundance sensitivity is in demand.

An online method to determine chlorine stable isotope composition by continuous flow isotope ratio mass spectrometry (CF-IRMS) coupled with a Gasbench Ⅱ

An online method using continuous flow isotope ratio mass spectrometry （CF-IRMS） interfaced with a Gasbench Ⅱ was presented to determine chlorine stable isotope composition. Silver chloride （AgCl） was quantitatively derived from chloride by using silver nitrate （AgNO3）, and then was reacted with iodomethane （CH3Ⅰ） to produce methyl chloride （CH3Cl）. A GasBench Ⅱ equipped with a PoraPlot Q column was used to separate CH3Cl from any other gas species. Finally, chlorine stable isotope analysis was carried out on CH3Cl introduced to the IRMS in a helium stream via an active open split. The minimum amount of Cl used in this method is of the order of 1.4 μmol. Inter-laboratory and inter-technique comparisons show that the total uncertainty incorporating both the precision and accuracy of this method is better than 0.007%. Furthermore, ten seawaters sampled from different locations have a narrow δ37Cl value range from -0.008% to 0.010%, with a mean value of （0.000±0.006）%. This supports the assumption that any seawater can be representative of standard mean ocean chloride （SMOC） and used as an international reference material.

Seasonal changes in TC and WSOC and their ^13C isotope ratios in Northeast Asian aerosols： land surface–biosphere–atmosphere interactions

In order to understand the relative importance of anthropogenic and biological sources of carbonaceous aerosols in Northeast Asia,we measured total carbon(TC)and water-soluble organic carbon(WSOC)and their stable carbon isotope ratios(d^(13)C)in total suspended particulates collected from Sapporo,northern Japan(43.07°N,141.36°E)over a 1-year period(during 2 September 2009and 5 October 2010).Temporal variations of TC showed a gradual decrease from mid-autumn to winter followed by a gradual increase to growing season with a peak in early summer.Both d^(13)C_(TC)and d^(13)C_(WSOC)showed very similar temporal trends with a gradual enrichment of^(13)C from mid-autumn to winter followed by a depletion in the^(13)C to early summer and thereafter it remained stable,except for few cases.Based on the results obtained together with the air mass trajectories,we found that biogenic emissions including biological particles(e.g.,pollen)and secondary organic aerosol formation from biogenic volatile organic compounds are the important sources of carbonaceous aerosols in spring/summer whereas fungal spores from soil and biomass burning and enhanced fossil fuel combustion contribute significantly in autumn/winter and in winter,respectively,in Northeast Asia.

Evaluation on nitrogen isotopes analysis in high-C/N-ratio plants using elemental analyzer/isotope ratio mass spectrometry

Elemental analyzer/isotope ratio mass spectrometry(EA/TRMS) has been widely applied to analyze the^(15)N/^(14)N isotope composition(δ^(15)N) of plants and soils,but the δ^(15)N results may be inaccurate due to incomplete combustion of the high-C/N-ratio plant samples by EA.Therefore,it is necessary to develop a method to solve the problem of imperfect combustion.In this study,we used two methods:1) adding copper oxide powder to the samples,and 2) increasing the O_2 flow(from 100 mL min^(-1) to 200 mL min^(-1)) for the auto sampler inlet purge line of the EA.The δ^(15)N values of the plant samples became more positive and tended to be stable after complete combustion.Also,the required blank samples for each plant sample decreased with increasing amount of the added CuO powder.However,at 200 mL min^(-1) of the oxygen flow in the EA,complete combustion could not be achieved without adding copper oxide,but this was done with decreased amount of CuO powder.Therefore,mixing cupric oxide into the high-C/N-ratio samples was an efficient,simple and convenient way to solve the problem of imperfect combustion in the EA.

A Simple and Fast Separation Method of Fe Employing Extraction Resin for Isotope Ratio Determination by Multicollector ICP-MS

A new, simple and fast separation method for Fe using an extraction chromatographic resin, Aliquat 336 (commercially available as TEVA resin) has been developed. A one milliliter column containing 0.33 mL TEVA resin on 0.67 mL CG-71C was used.Iron was adsorbed with 6mol·L-1 HCl + H2O2 on TEVA resin, and recovered with 2 mol·L-1HNO3. The recovery yield and total blank were 93.5 ± 6.5% and 6 ng, respectively. Theseparation method is simple, and takes < 2 hours. For evaluation of the Fe separation, Fe isotope ratios were measured by a double-spike method employing multicollector inductively coupled plasma source mass spectrometry (MC-ICP-MS) with repeatability of 0.06‰ (SD) for the standard solution and ~0.05‰ for the silicate samples. Therefore, the column chemistry developed in this study is a viable option for Fe isotope ratio measurement by MC-ICP-MS.

Evaluation of Pollution Sources of Zinc in Tokyo Bay Based on Zinc Isotope Ratio in Sediment Core

This study evaluated the sources of Zn pollution in Tokyo Bay, Japan, on the basis of δ66Zn in a sediment core. The Zn concentration in sediments in the 1980s-2000s was considerably higher than the background concentration, suggesting that there remain important sources of Zn in the bay. The δ66Zn (+0.51‰) of anthropogenic Zn estimated in the core was significantly higher than those (approximately –0.1‰ - +0.2‰) of treated water from sewage treatment plants and vehicle-related sources. A large number of electroplating plants are located in Tokyo areas. It is assumed that Zn in effluents from electroplating operations is isotopically heavier owing to a negative isotopic effect on Zn electroplating. This tends to support the hypothesis that river bottom sediments, which were contaminated with Zn in the untreated effluents from electroplating plants in the past, are the principal sources of anthropogenic Zn in Tokyo Bay in the 1980s-2000s.

Oxygen and hydrogen isotope ratios of chert from the Sixtymile Formation in Grand Canyon National Park,USA：a warm palaeoclimate,freshwater deposit

New oxygen and hydrogen isotope ratios of chert from middle, intraformational breccias, and upper breccia members of the Sixtymile Formation（SMF） in eastern Grand Canyon National Park（AZ） yield palaeoclimate estimates between 27 and 33℃. The isotopic compositions of cherts define a domain approximately parallel to the meteoric water line when plotted on a δD–δ-（18）O diagram; these data indicate that meteoric water was involved during formation of the chert. In thin section, the absence of interlocking mega quartz（〉35 lm） and silicafilled fractures and veins, along with preserved micromorphological silica fabrics, suggest that the chert has not been permeated by later hydrothermal fluids. Petrographic observations in thin section such as cyclic silica precipitation phases and glaebular micromorphologic fabrics lend support to the interpretation that meteoric waters were involved during chert precipitation. The post 742 Ma SMF has been correlated with diamictite（transition） beds of the Kingston Peak Formation（CA）, which in turn have been interpreted to have been deposited during the Sturtian Ice Age（-750–700 Ma）. Absence of facetted and striated clasts and other diagnostic glaciogenic features in the SMF,an unconformable contact with the stratigraphically older Chuar Group, coupled with warm palaeotemperature data inferred from stable isotope values of chert, tentatively suggest that deposition of sediment in the SMF likely did not take place during the Sturtian Ice Age.

Carbon isotope ratios of n-alkanoic acids: new organic proxies for paleo-productivity in Antarctic ponds

Primary productivity in the Antarctic aquatic environment with simple ecosystems is sensitive to climate and environmental fluctuations.We investigatedδ13C values for n-alkanoic acids derived from phototrophic organisms in a lacustrine sediment core(IIL3)to indicate primary productivity in ponds on Inexpressible Island in the western Ross Sea,Antarctica.Short-chain n-alkanoic acids(C14–C18)were abundant in the IIL3 sediment profile.The carbon isotope ratios of short-chain n-alkanoic acids in the sediment samples and floating microbial mats were similar,indicating that the short-chain n-alkanoic acids in the IIL3 sediment profile predominantly originated from phototrophic organisms.Theδ13C values for the short-chain n-alkanoic acids varied widely through the sediment profile,and 13C-enrichment of n-alkanoic acids was most likely related to high productivity due to carbon-limited conditions caused by enhanced photosynthetic efficiency.Theδ13C values for the n-alkanoic acids changed over the past 3200 years in similar ways to organic proxies for aquatic productivity(n-alkanoic acid and sterol sedimentary fluxes).C16 n-alkanoic acid was enriched in 13C in periods of high aquatic productivity~750–1650 and 3000–3200 a BP but depleted in 13C in periods of relatively low productivity~150–600 and 2500–3000 a BP.The results indicated that carbon isotope ratios of lipids from phototrophic organisms could be used as new proxies to reconstruct paleo-productivity in Antarctic lakes and ponds and therefore improve our understanding of past climate changes.

High-Precision Direct Determination of the ^(87)Sr/^(86)Sr Isotope Ratio of Bottled Sr-Rich Natural Mineral Drinking Water Using MC-ICP-MS

Strontium has four naturally occurring stable isotopes,84Sr,86Sr,87Sr,and 88Sr,with abundances of 0.56,9.87,approximately 7.04,and 82.53 atomic %,respectively.The 87Sr/86Sr isotope ratio is variable due to the addition of radiogenic 87Sr produced by the beta decay of 87Rb with a half-life of 4.88 ± 0.05 Ga.Thus,

Differential distribution of authenticity results of different varieties of refined honey based on stable isotope ratio method

Objective Using the stable isotope ratio method for the authenticity identification and variety identification of refined honey.Methods In this paper,a total of 17 samples of different varieties of refined honey were used to obtain refined honey proteins by precipitation with sodium tungstate solution and sulphuric acid solution.The isotope mass spectrometer was used to simultaneously detect theδ^(13)C values of refined honey proteins and refined honey as well as theδ^(18)O andδ^(2)H values of refined honey,processed of the results obtained,analysed the authenticity of the samples and conduct a variety identification study.Results Tested of the resulting honey samples,the results showed that four batches of refined honey did not up to standard,two batches of C-4 vegetable syrup were detected as adulterated,and two batches of protein were not detected.Theδ^(18)O andδ^(2)H values of refined honey were also found to be effective in distinguishing the varietal origin of refined honey to a certain extent.Conclusions The stable isotope ratio method is useful in the authenticity identification of refined honey,and provides new ideas to further promote the authenticity of refined honey and variety identification research.

Evaporative enrichment of stable isotopes(δ^(18)O and δD) in lake water and the relation to lake-level change of Lake Qinghai, Northeast Tibetan Plateau of China

Stable isotopic compositions （δ18O and 6D） have been utilized as a useful indicator for evaluating the current and historical climatic and environmental changes. Therefore, it is vital to understand the relationship be- tween the stable isotopic contents in lake water and the variations of lake level, particularly in Lake Qinghai, China. In this study, we analyzed the variations of isotope compositions （δ18O, 6D and d-excess） in lake water and pre- cipitation by using the samples that were collected from Lake Qinghai region during the period from 2009 to 2012. The results showed that the average isotopic contents of δ18O and 6D in lake water were higher than those in pre- cipitation, which were contrary to the variations of d-excess. The linear regression correlations between δ18O and 6D in lake water and precipitation showed that the local evaporative line （LEL） in lake water （δD=5.88δ18O-2.41） deviated significantly from the local meteoric water line （LMWL）in precipitation （δD=8.26δ18O＋16.91）, indicating that evaporative enrichment had a significant impact on isotopic contents in lake water. Moreover, we also quanti- fied the Eli ratio （evaporation-to-input ratio） in Lake Qinghai based on the lake water isotopic enrichment model derived from the Rayleigh equation. The changes of E/I ratios （ranging from 0.29 to 0.36 between 2009 and 2012） clearly revealed the shifts of lake levels in Lake Qinghai in recent years. The average E/I ratio of 0.40 reflected that water budget in Lake Qinghai was positive, and consistent with the rising lake levels and the increasing lake areas in many lakes of the Tibetan Plateau. These findings provide some evidences for studying the hydrological balance or water budget by using δ18O values of lake sedimentary materials and contribute to the reconstruction of paleo- lake water level and paleoclimate from an isotopic enrichment model in Lake Qinghai.

O,H,and Sr isotope evidence for origin and mixing processes of the Gudui geothermal system,Himalayas,China

Tho Gudui geothermal field records the highest temperature at equivalent borehole depths among the lainland hydrothermal systems in China's Mainland.Located about 150 km southeast of Lhasa City,the capital of Tibet,the Gudui geothermal field belongs to the Sangri-Cuona rift belt,also known as the Sangri-Cuona geothermal belt,and is representative of the non-volcanic geothermal systems in the Himalayas.In this study,oxygen-18 and deuterium isotope compositions as well as 87Sr/86Sr ratios of water samples collected from the Gudui geothermal field were characterized to understand the origin and mixing processes of the geothermal fluids at Gudui.Hydrogen and oxygen isotope plots show both,deep and shallow reservoirs in the Gudui geothermal field.Deep geothermal fluids are the mixing product of magmatic and infiltrating snow-melt water.Calculations show that the magma fluid component of the deep geothermal fluids account for about 21.10%-24.04%;magma fluids lay also be a contributing source of lithium.The linear relationship of the 87Sr/86Sr isotopic ratio versus the 1/Sr plot indicates that shallow geothermal fluids form from the mixing of deep geothermal fluids with cold groundwater.Using a binary mixing model with deep geothermal fluid and cold groundwater as two end-members,the nixing ratios of the latter in most surface hot springs samples were calculated to be between 5% and 10%.Combined with basic geological characteristics,hydrogen and oxygen isotope characteristics,strontium concentration,87Sr/(86)Sr ratios,and the binary mixing model,we infer the 6 th-Class Reservoirs Evolution Conceptual Model(6-CRECM) for the Gudui geothermal system.This model represents an idealized summary of the characteristics of the Gudui geothermal field based on our comprehensive understanding of the origin and mixing processes of the geothermal fluid in Gudui.This study may aid in identifying the geothermal and geochemical origin of the Gudui high-temperature hydrothermal systems in remote Tibet of China,whose potential for geothermal development and utilization is enormous and untapped.

Determination of Hf–Sr–Nd isotopic ratios by MC-ICP-MS using rapid acid digestion after flux-free fusion in geological materials

In this study, we established a rapid acid digestion for determining Hf-Sr-Nd isotopic ratios of geological samples by using MC-ICP-MS. Conditions of 1600 ℃ for 1 min and 1400 ℃ for 1 min were adopted for fusing intrusive rocks and extrusive rocks, respectively. The rapid acid digestion technique is superior in digestion time compared with high-pressure PTFE bomb method. The procedural blanks of the method were also lower than that flux fusion. Replicate analyses of international certified reference materials （CRMs） indicate that isotopic ratios of ^176Hf/^177Hf, ^87Sr/^86Sr and 143Nd/144Nd agree well with previously published data. The external reproducibility （2SD, n = 5） of ten CRMs are ±0.000030 for ^87Sr/^86Sr, ± 0.000030 for ^143Nd/^144Nd, and ±0.000018 for ^176Hf/^177Hf.

Hydrogen and Oxygen Isotope Fractionation Mechanism in the Hydrothermal System and Its Geologic Significance

The geochemical behaviors of hydrogen and oxygen isotopes in the hydrothermal system and their inher-ent relationship with the water / rock exchange are discussed in this paper In addition to the temperature con-ditions, the effective W / R ratio is another factor controlling the changes in H and O isotope compositions ofthe altered rock and hydrothermal water. Besides, the application and geological significance of the water-rockexchange theory are also discussed in the light of the H and O isotope compositions and their variation charac-teristics of the mineralizing hydrothermal water and altered rocks from several mineral deposits. Finally, abrief evolutional model of H and O istotope compositions of meteoric and magmatic hydrothermal waters in ahydrothermal system is given.

Delineating the Source of Lead in the Urban Atmospheric Dust Based on Stable Isotopic Ratio: A Case Study from Panzhihua City of Southwest China

Atmospheric lead pollution is a global problem.Mining,coal mining,iron and steel smelting,and chemical and coal-fired power plants are major industries in Panzhihua City of southwest China.Many toxic and harmful heavy metals,including Pb,are emitted in production activities.Pb seriously affects human health and natural ecosystems.Thus,Pb source tracing is important for Pb pollution control(Souto-Oliveira et al.,2018;Zhao et al.,2015).

LEAD ISOTOPE STUDIES ON ANCIENT BRONZE DRUMS OF GUANGXI CHINA

A study has been reported on 208Pb/206Pb and 207Pb/206Pb ratio variations in ancient drums and Cu-., Pb- ores from Guangxi, China and can indicate that the Cu- and Pb- bearing ores for making the Beiliu and the Lingshan type drums were taken from Tongshiling of Beiliu County and its vicinity, that were not only ancient sites for smelting the copper ores, but possibly also for casting the bronze drums. Some of the Lengshuichong type drums have abnormal Pb isotopic ratios, which means that they were made of special ore sources, one of the possibilities is that the ore material or the drums were transported from South- East Asia to Guangxi Province, because they have been excavated there too.

CAUBRATION METHOD IN ISOTOPIC CARBON ANALYSIS

A very simple basic equation for the comparator technique is derived for the determination of 13C/12C ratio in biological samples by proton induced gamma- ray emission. On the basis of this treatments a new series of experiments has been made at a 2×1.7 tandem accelerator that proved conclusion about the method.

DOUBLE SUBSTITUTE CALIBRATION FOR THE ISOTOPIC RATIO MEASUREMENT AMONG RARE EARTH ELEMENTS

Abstract: Through the application of the method of double substitute calibration using the true isotopic ratios of cerium and europium of our laboratory standards, the atomic weight of ytterbium has been determined as Ac(Yb) 173. 0428(15) on Zσ basis.