Articles | Volume 18, issue 9
11 May 2021
Research article | 11 May 2021
Evaluating the response of δ13C in Haloxylon ammodendron, a dominant C4 species in Asian desert ecosystems, to water and nitrogen addition as well as the availability of its δ13C as an indicator of water use efficiency
Zixun Chen et al.
No articles found.
Chuanhua Ren, Xin Huang, Tengyu Liu, Yu Song, Zhang Wen, Xuejun Liu, Aijun Ding, and Tong Zhu
Geosci. Model Dev. Discuss.,
Preprint under review for GMDShort summary
Ammonia in the atmosphere has wide impacts on the ecological environment and air quality, and its emission from soil volatilization is highly sensitive to meteorology, making it challenging to be well captured in models. We developed a dynamic emission model capable of calculating ammonia emission interactively with meteorological and soil conditions. Such a coupling of soil emission with meteorology provides a better understanding of ammonia emission and its contribution to atmospheric aerosol.
Pu Liu, Jia Ding, Lei Liu, Wen Xu, and Xuejun Liu
Atmos. Chem. Phys., 22, 9099–9110,Short summary
Ammonia (NH3) is the important alkaline gas and the key component of fine particulate matter. We used satellite-based observations to analyze the changes in hourly NH3 concentrations and estimated surface NH3 concentrations and NH3 emissions in China. This study shows enormous potential for using satellite data to estimate surface NH3 concentrations and NH3 emissions and provides an important reference for understanding NH3 variation in China.
Fanlei Meng, Yibo Zhang, Jiahui Kang, Mathew R. Heal, Stefan Reis, Mengru Wang, Lei Liu, Kai Wang, Shaocai Yu, Pengfei Li, Jing Wei, Yong Hou, Ying Zhang, Xuejun Liu, Zhenling Cui, Wen Xu, and Fusuo Zhang
Atmos. Chem. Phys., 22, 6291–6308,Short summary
PM2.5 pollution is a pressing environmental issue threatening human health and food security globally. We combined a meta-analysis of nationwide measurements and air quality modeling to identify efficiency gains by striking a balance between controlling NH3 and acid gas emissions. Persistent secondary inorganic aerosol pollution in China is limited by acid gas emissions, while an additional control on NH3 emissions would become more important as reductions in SO2 and NOx emissions progress.
Pooja V. Pawar, Sachin D. Ghude, Chinmay Jena, Andrea Móring, Mark A. Sutton, Santosh Kulkarni, Deen Mani Lal, Divya Surendran, Martin Van Damme, Lieven Clarisse, Pierre-François Coheur, Xuejun Liu, Gaurav Govardhan, Wen Xu, Jize Jiang, and Tapan Kumar Adhya
Atmos. Chem. Phys., 21, 6389–6409,Short summary
In this study, simulations of atmospheric ammonia (NH3) with MOZART-4 and HTAP-v2 are compared with satellite (IASI) and ground-based measurements to understand the spatial and temporal variability of NH3 over two emission hotspot regions of Asia, the IGP and the NCP. Our simulations indicate that the formation of ammonium aerosols is quicker over the NCP than the IGP, leading to smaller NH3 columns over the higher NH3-emitting NCP compared to the IGP region for comparable emissions.
Baozhu Ge, Syuichi Itahashi, Keiichi Sato, Danhui Xu, Junhua Wang, Fan Fan, Qixin Tan, Joshua S. Fu, Xuemei Wang, Kazuyo Yamaji, Tatsuya Nagashima, Jie Li, Mizuo Kajino, Hong Liao, Meigen Zhang, Zhe Wang, Meng Li, Jung-Hun Woo, Junichi Kurokawa, Yuepeng Pan, Qizhong Wu, Xuejun Liu, and Zifa Wang
Atmos. Chem. Phys., 20, 10587–10610,Short summary
Performances of the simulated deposition for different reduced N (Nr) species in China were conducted with the Model Inter-Comparison Study for Asia. Results showed that simulated wet deposition of oxidized N was overestimated in northeastern China and underestimated in south China, but Nr was underpredicted in all regions by all models. Oxidized N has larger uncertainties than Nr, indicating that the chemical reaction process is one of the most importance factors affecting model performance.
Lei Liu, Xiuying Zhang, Wen Xu, Xuejun Liu, Xuehe Lu, Jing Wei, Yi Li, Yuyu Yang, Zhen Wang, and Anthony Y. H. Wong
Atmos. Chem. Phys., 20, 8641–8658,Short summary
Excessive atmospheric reactive nitrogen (Nr) deposition can cause a series of negative effects. Thus, it is necessary to accurately estimate Nr deposition to evaluate its impact on the ecosystems and environment. Scientists attempted to estimate surface Nr concentration and deposition using satellite retrievals. We give a thorough review of recent advances in estimating surface Nr concentration and deposition using satellite retrievals of NO2 and NH3 and summarize the existing challenges.
Chongjuan Chen, Yingjie Wu, Shuhan Wang, Zhaotong Liu, and Guoan Wang
Revised manuscript not acceptedShort summary
Relationships between leaf δ15N and concentrations of leaf metallic nutrients have not been examined as yet though they could enhance our understanding of N cycling. By analyzing 624 non-N2-fixing plant samples, we first found that leaf δ15N was positively correlated with leaf K, Ca, Mg and Zn, negatively correlated with leaf Fe, and not related to leaf Mn. All of them together explained 55.7 % of variations in leaf δ15N. This study emphasized the significance of metallic nutrients in N cycling.
Lei Liu, Xiuying Zhang, Anthony Y. H. Wong, Wen Xu, Xuejun Liu, Yi Li, Huan Mi, Xuehe Lu, Limin Zhao, Zhen Wang, Xiaodi Wu, and Jing Wei
Atmos. Chem. Phys., 19, 12051–12066,Short summary
Agricultural production has greatly increased emissions of ammonia (NH3) to the atmosphere. Sparse measurements of surface NH3 concentrations make it challenging and difficult to understand the global distribution of surface NH3 concentrations in both time and space. Estimating surface NH3 concentrations is critically important for modeling the dry deposition of NH3, which has important impacts on the natural environment. This paper provides the satellite-based global assessment of surface NH3.
Mingxu Liu, Xin Huang, Yu Song, Tingting Xu, Shuxiao Wang, Zhijun Wu, Min Hu, Lin Zhang, Qiang Zhang, Yuepeng Pan, Xuejun Liu, and Tong Zhu
Atmos. Chem. Phys., 18, 17933–17943,
Yangyang Zhang, Aohan Tang, Dandan Wang, Qingqing Wang, Katie Benedict, Lin Zhang, Duanyang Liu, Yi Li, Jeffrey L. Collett Jr., Yele Sun, and Xuejun Liu
Atmos. Chem. Phys., 18, 16385–16398,Short summary
Our study is the first to continually monitor the vertical concentration profile of NH3 in urban Beijing. Weekly concentrations averaged 13.3 ± 4.8 μg m−3. The highest NH3 concentrations were always observed between 32 and 63 m, decreasing toward the surface and toward higher altitudes. Our results demonstrate a NH3 rich atmosphere in urban Beijing, from the ground to at least 320 m. Regional transport from the south (intensive agricultural regions) contributed high NH3 concentrations in Beijing.
Wen Xu, Lei Liu, Miaomiao Cheng, Yuanhong Zhao, Lin Zhang, Yuepeng Pan, Xiuming Zhang, Baojing Gu, Yi Li, Xiuying Zhang, Jianlin Shen, Li Lu, Xiaosheng Luo, Yu Zhao, Zhaozhong Feng, Jeffrey L. Collett Jr., Fusuo Zhang, and Xuejun Liu
Atmos. Chem. Phys., 18, 10931–10954,Short summary
Our main results demonstrate that atmospheric Nr pollution in eastern China is more serious in the northern region than in the southern region. Any effects of current emission controls are not yet apparent in Nr pollution. NH3 emissions from fertilizer use were the largest contributor (36 %) to total inorganic Nr deposition. Our results provide useful information for policy-makers that mitigation of NH3 emissions should be a priority to tackle serious N deposition.
Ping Yue, Xiaoqing Cui, Yanming Gong, Kaihui Li, Keith Goulding, and Xuejun Liu
Biogeosciences, 15, 2007–2019,Short summary
Precipitation and N deposition significantly increased Rs, but warming decreased Rs, which depended mainly on the variation of soil moisture. The interactive response of Rs to combinations of the factors was much less than that of any single factor, and the interactions of multiple factors largely reduced between-year variation of Rs more than any single factor, suggesting that the carbon cycle in temperate deserts could be profoundly influenced by positive carbon–climate feedbacks.
Chongjuan Chen, Yufu Jia, Yuzhen Chen, Imran Mehmood, Yunting Fang, and Guoan Wang
Biogeosciences, 15, 369–377,Short summary
The south slope of Tian Shan differs from the north slope in environment. The study showed that leaf δ15N, soil δ15N and △δ15Nleaf-soil on the south slope were greater than those on the north slope. The significant influential factors of leaf and soil δ15N on the south slope were different from those on the north slope. The results suggested that the south slope has higher soil N transformation rates than the north slope and relationships between leaf and soil δ15N and environment are localized.
Lin Zhang, Youfan Chen, Yuanhong Zhao, Daven K. Henze, Liye Zhu, Yu Song, Fabien Paulot, Xuejun Liu, Yuepeng Pan, Yi Lin, and Binxiang Huang
Atmos. Chem. Phys., 18, 339–355,Short summary
Substantial differences exist in current estimates of agricultural ammonia emissions in China, hindering understanding of their environmental consequences. This study applies both bottom-up and top-down methods to better quantify agricultural ammonia sources in China using observations from satellite and surface networks interpreted by a chemical transport model. Our estimate of annual Chinese anthropogenic ammonia emission is 11.7 tg (teragram) for 2008 with a strong seasonality peak in summer.
Lei Liu, Xiuying Zhang, Wen Xu, Xuejun Liu, Yi Li, Xuehe Lu, Yuehan Zhang, and Wuting Zhang
Atmos. Chem. Phys., 17, 9365–9378,Short summary
We conducted temporal trend analysis of atmospheric NH3 and NO2 in China since 1980 based on emission data (during 1980–2010), satellite observations (for NH3 since 2008 and for NO2 since 2005) and atmospheric chemistry transport modeling (during 2008–2015). Our findings provide an overall insight into the temporal trends in both NO2 and NH3 since 1980, and the multivariate data used in this study have implications for estimating long-term Nr deposition datasets.
Jin Ling Lv, Andreas Buerkert, Guo Jun Liu, Chao Yan Lv, Xi Ming Zhang, Kai Hui Li, and Xue Jun Liu
Manuscript not accepted for further reviewShort summary
Very little research has been conducted to quantify atmospheric N deposition in agro-pastoral transition zones. Based on this, we chose a typical agro-pastoral transition zone in the border area of China and Mongolia and used scientific method to compare the dynamics and amounts of wet and dry N deposition in this area. This will hopefully supply the scientific evidence required to introduce more rational N application and manure management strategies for similar areas throughout central Asia.
Wen Xu, Wei Song, Yangyang Zhang, Xuejun Liu, Lin Zhang, Yuanhong Zhao, Duanyang Liu, Aohan Tang, Daowei Yang, Dandan Wang, Zhang Wen, Yuepeng Pan, David Fowler, Jeffrey L. Collett Jr., Jan Willem Erisman, Keith Goulding, Yi Li, and Fusuo Zhang
Atmos. Chem. Phys., 17, 31–46,Short summary
This paper evaluates the effectiveness of emission control measures implemented in Beijing during the Parade Blue period by integrating our own results, official-released data and modeling data. We demonstrate that emission control measures make a major contribution to air quality improvement in Beijing and surrounding regions. We conclude a joint local and regional control of secondary aerosol precursors to be key to curbing air pollution in Beijing.
Yunhua Chang, Xuejun Liu, Congrui Deng, Anthony J. Dore, and Guoshun Zhuang
Atmos. Chem. Phys., 16, 11635–11647,Short summary
First, we establish a pool of isotopic signatures (δ15N–NH3) for the major NH3 emission sources in China. Second, we demonstrated that the isotopic source signatures of NH3 represent an emerging tool for partitioning NH3 sources in urban atmospheres.
Yufu Jia, Guoan Wang, Qiqi Tan, and Zixun Chen
Biogeosciences, 13, 5057–5064,Short summary
Soil organic carbon can be used for climate reconstruction and carbon cycle study. This work assessed the effect of temperature on surface soil δ13C by an investigation from 27 sites across a temperature gradient along an isohyet. This study shows that soil type and vegetation type had influences on soil δ13C, while temperature was not related to soil δ13C. This suggests that organic carbon isotopes in sediments cannot be used for the paleotemperature reconstruction.
Enzai Du, Wim de Vries, Wenxuan Han, Xuejun Liu, Zhengbing Yan, and Yuan Jiang
Atmos. Chem. Phys., 16, 8571–8579,Short summary
Accelerated N emissions in China may lead to an imbalance of atmospheric nutrient inputs in various ecosystems. Our assessment of P and N deposition in China's forests showed relatively high rates of P deposition, but they were accompanied by even much higher N deposition, resulting in high N : P deposition ratios. P and N deposition both showed a power-law increase with closer distance to the nearest large cities. Our results suggest an anthropogenic imbalance of regional N and P cycling.
Yaning Kang, Mingxu Liu, Yu Song, Xin Huang, Huan Yao, Xuhui Cai, Hongsheng Zhang, Ling Kang, Xuejun Liu, Xiaoyuan Yan, Hong He, Qiang Zhang, Min Shao, and Tong Zhu
Atmos. Chem. Phys., 16, 2043–2058,Short summary
The multi-year (1980–2012) comprehensive ammonia emissions inventories were compiled for China on 1 km × 1 km grid. Various realistic parameters (ambient temperature, wind speed, soil acidity, synthetic fertilizer types, etc.) were considered in these inventories to synthetically refine the emission factors of ammonia volatilization according to local agricultural practice. This paper shows the interannual trend and spatial distribution of ammonia emissions in details over recent decades.
W. Xu, X. S. Luo, Y. P. Pan, L. Zhang, A. H. Tang, J. L. Shen, Y. Zhang, K. H. Li, Q. H. Wu, D. W. Yang, Y. Y. Zhang, J. Xue, W. Q. Li, Q. Q. Li, L. Tang, S. H. Lu, T. Liang, Y. A. Tong, P. Liu, Q. Zhang, Z. Q. Xiong, X. J. Shi, L. H. Wu, W. Q. Shi, K. Tian, X. H. Zhong, K. Shi, Q. Y. Tang, L. J. Zhang, J. L. Huang, C. E. He, F. H. Kuang, B. Zhu, H. Liu, X. Jin, Y. J. Xin, X. K. Shi, E. Z. Du, A. J. Dore, S. Tang, J. L. Collett Jr., K. Goulding, Y. X. Sun, J. Ren, F. S. Zhang, and X. J. Liu
Atmos. Chem. Phys., 15, 12345–12360,Short summary
The annual average concentrations (1.3-47.0µg N m-3) and dry plus wet/bulk deposition fluxes (2.9-83.3kg N ha-1 yr-1) of inorganic Nr species ranked by land use as urban > rural > background sites and by regions as north China > southeast China > southwest China > northeast China > northwest China > Tibetan Plateau, reflecting the impact of anthropogenic Nr emission. Average dry and wet/bulk N deposition fluxes were 20.6 ± 11.2 and 19.3 ± 9.2kg kg N ha-1 yr-1 across China, respectively.
M. Van Damme, L. Clarisse, E. Dammers, X. Liu, J. B. Nowak, C. Clerbaux, C. R. Flechard, C. Galy-Lacaux, W. Xu, J. A. Neuman, Y. S. Tang, M. A. Sutton, J. W. Erisman, and P. F. Coheur
Atmos. Meas. Tech., 8, 1575–1591,Short summary
In this study, comprehensive ground-based data sets (Europe, China, Africa and United States) are used to evaluate NH3 measurements from IASI. Global yearly and regional monthly comparisons show fair agreement, while hourly measurements are used to investigate the limitations of direct comparisons. In addition, dense airborne measurements are explored and show the highest correlation coefficients in this study. Finally, the urgent need for independent NH3 column measurements is discussed.
J. Zhang, L. Gu, F. Bao, Y. Cao, Y. Hao, J. He, J. Li, Y. Li, Y. Ren, F. Wang, R. Wu, B. Yao, Y. Zhao, G. Lin, B. Wu, Q. Lu, and P. Meng
Biogeosciences, 12, 15–27,
Related subject area
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Initial results from the Espan Spring in Fürth, GermanyStable isotope ratios in seawater nitrate reflect the influence of Pacific water along the northwest Atlantic marginHigh-resolution 14C bomb peak dating and climate response analyses of subseasonal stable isotope signals in wood of the African baobab – a case study from OmanGeographic variability in freshwater methane hydrogen isotope ratios and its implications for global isotopic source signaturesSeasonality of nitrogen sources, cycling, and loading in a New England river discerned from nitrate isotope ratiosModern silicon dynamics of a small high-latitude subarctic lakeRadium-228-derived ocean mixing and trace element inputs in the South AtlanticNitrogen isotopic fractionations during nitric oxide production in an agricultural soilSilicon uptake and isotope fractionation dynamics by crop speciesBarium stable isotopes as a fingerprint of biological cycling in the Amazon River basinBottomland hardwood forest growth and stress response to hydroclimatic variation: evidence from dendrochronology and tree ring Δ13C valuesN2O isotope approaches for source partitioning of N2O production and estimation of N2O reduction – validation with the 15N gas-flux method in laboratory and field studiesTechnical note: Single-shell δ11B analysis of Cibicidoides wuellerstorfi using femtosecond laser ablation MC-ICPMS and secondary ion mass spectrometryBiogeochemical evidence of anaerobic methane oxidation and anaerobic ammonium oxidation in a stratified lake using stable isotopesEffects of 238U variability and physical transport on water column 234Th downward fluxes in the coastal upwelling system off PeruDo degree and rate of silicate weathering depend on plant productivity?Alpine Holocene tree-ring dataset: age-related trends in the stable isotopes of cellulose show species-specific patternsIdeas and perspectives: The same carbon behaves like different elements – an insight into position-specific isotope distributionsSeasonal dynamics of the COS and CO2 exchange of a managed temperate grasslandLeaf-scale quantification of the effect of photosynthetic gas exchange on Δ17O of atmospheric CO2The stable carbon isotope signature of methane produced by saprotrophic fungiUnderstanding the effects of early degradation on isotopic tracers: implications for sediment source attribution using compound-specific isotope analysis (CSIA)Oxygen isotope composition of waters recorded in carbonates in strong clumped and oxygen isotopic disequilibriumIsotopic evidence for alteration of nitrous oxide emissions and producing pathways' contribution under nitrifying conditionsTrace element composition of size-fractionated suspended particulate matter samples from the Qatari Exclusive Economic Zone of the Arabian Gulf: the role of atmospheric dustBenthic carbon fixation and cycling in diffuse hydrothermal and background sediments in the Bransfield Strait, AntarcticaChanges in gross oxygen production, net oxygen production, and air-water gas exchange during seasonal ice melt in Whycocomagh Bay, a Canadian estuary in the Bras d'Or Lake systemPlants or bacteria? 130 years of mixed imprints in Lake Baldegg sediments (Switzerland), as revealed by compound-specific isotope analysis (CSIA) and biomarker analysisCommercial traceability of Arapaima spp. fisheries in the Amazon basin: can biogeochemical tags be useful?Distribution of Fe isotopes in particles and colloids in the salinity gradient along the Lena River plume, Laptev SeaEarly season N2O emissions under variable water management in rice systems: source-partitioning emissions using isotope ratios along a depth profileEvolution of 231Pa and 230Th in overflow waters of the North AtlanticSouthern Ocean controls of the vertical marine δ13C gradient – a modelling studyNegligible isotopic fractionation of nitrogen within temperate Zostera spp. meadowsEcosystem fluxes of carbonyl sulfide in an old-growth forest: temporal dynamics and responses to diffuse radiation and heat waves
Adam Francis, Raja S. Ganeshram, Robyn E. Tuerena, Robert G. M. Spencer, Robert M. Holmes, Jennifer A. Rogers, and Claire Mahaffey
Biogeosciences, 20, 365–382,Short summary
Climate change is causing extensive permafrost degradation and nutrient releases into rivers with great ecological impacts on the Arctic Ocean. We focused on nitrogen (N) release from this degradation and associated cycling using N isotopes, an understudied area. Many N species are released at degradation sites with exchanges between species. N inputs from permafrost degradation and seasonal river N trends were identified using isotopes, helping to predict climate change impacts.
Mohamed Ayache, Jean-Claude Dutay, Kazuyo Tachikawa, Thomas Arsouze, and Catherine Jeandel
Biogeosciences, 20, 205–227,Short summary
The neodymium (Nd) is one of the most useful tracers to fingerprint water mass provenance. However, the use of Nd is hampered by the lack of adequate quantification of the external sources. Here, we present the first simulation of dissolved Nd concentration and Nd isotopic composition in the Mediterranean Sea using a high-resolution model. We aim to better understand how the various external sources affect the Nd cycle and particularly assess how it is impacted by atmospheric inputs.
Marta Santos-Garcia, Raja S. Ganeshram, Robyn E. Tuerena, Margot C. F. Debyser, Katrine Husum, Philipp Assmy, and Haakon Hop
Biogeosciences, 19, 5973–6002,Short summary
Terrestrial sources of nitrate are important contributors to the nutrient pool in the fjords of Kongsfjorden and Rijpfjorden in Svalbard during the summer, and they sustain most of the fjord primary productivity. Ongoing tidewater glacier retreat is postulated to favour light limitation and less dynamic circulation in fjords. This is suggested to encourage the export of nutrients to the middle and outer part of the fjord system, which may enhance primary production within and in offshore areas.
Marlene Dordoni, Michael Seewald, Karsten Rinke, Kurt Friese, Robert van Geldern, Jakob Schmidmeier, and Johannes A. C. Barth
Biogeosciences, 19, 5343–5355,Short summary
Organic matter (OM) turnover into dissolved inorganic carbon (DIC) was investigated by means of carbon isotope mass balances in Germany's largest water reservoir. This includes a metalimnetic oxygen minimum (MOM). Autochthonous particulate organic carbon (POC) was the main contributor to DIC, with rates that were highest for the MOM. Generally low turnover rates outline the environmental fragility of this water body in the case that OM loads increase due to storm events or land use changes.
Frédérique M. S. A. Kirkels, Hugo J. de Boer, Paulina Concha Hernández, Chris R. T. Martes, Marcel T. J. van der Meer, Sayak Basu, Muhammed O. Usman, and Francien Peterse
Biogeosciences, 19, 4107–4127,Short summary
The distinct carbon isotopic values of C3 and C4 plants are widely used to reconstruct past hydroclimate, where more C3 plants reflect wetter and C4 plants drier conditions. Here we examine the impact of regional hydroclimatic conditions on plant isotopic values in the Godavari River basin, India. We find that it is crucial to identify regional plant isotopic values and consider drought stress, which introduces a bias in C3 / C4 plant estimates and associated hydroclimate reconstructions.
Mhlangabezi Mdutyana, Tanya Marshall, Xin Sun, Jessica M. Burger, Sandy J. Thomalla, Bess B. Ward, and Sarah E. Fawcett
Biogeosciences, 19, 3425–3444,Short summary
Nitrite-oxidizing bacteria in the winter Southern Ocean show a high affinity for nitrite but require a minimum (i.e., "threshold") concentration before they increase their rates of nitrite oxidation significantly. The classic Michaelis–Menten model thus cannot be used to derive the kinetic parameters, so a modified equation was employed that also yields the threshold nitrite concentration. Dissolved iron availability may play an important role in limiting nitrite oxidation.
Weitian Ding, Urumu Tsunogai, Fumiko Nakagawa, Takashi Sambuichi, Hiroyuki Sase, Masayuki Morohashi, and Hiroki Yotsuyanagi
Biogeosciences, 19, 3247–3261,Short summary
Excessive leaching of nitrate from forested catchments during storm events degrades water quality and causes eutrophication in downstream areas. Thus, tracing the source of nitrate increase during storm events in forested streams is important for sustainable forest management. Based on the isotopic compositions of stream nitrate, including Δ17O, this study clarifies that the source of stream nitrate increase during storm events was soil nitrate in the riparian zone.
Nicolas Séon, Romain Amiot, Guillaume Suan, Christophe Lécuyer, François Fourel, Fabien Demaret, Arnauld Vinçon-Laugier, Sylvain Charbonnier, and Peggy Vincent
Biogeosciences, 19, 2671–2681,Short summary
We analysed the oxygen isotope composition of bones and teeth of four marine species possessing regional heterothermies. We observed a consistent link between oxygen isotope composition and temperature heterogeneities recorded by classical methods. This opens up new perspectives on the determination of the thermoregulatory strategies of extant marine vertebrates where conventional methods are difficult to apply, but also allows us to investigate thermophysiologies of extinct vertebrates.
Yuwei Liu, Guofeng Zhu, Zhuanxia Zhang, Zhigang Sun, Leilei Yong, Liyuan Sang, Lei Wang, and Kailiang Zhao
Biogeosciences, 19, 877–889,Short summary
We took the water cycle process of soil–plant–atmospheric precipitation as the research objective. In the water cycle of soil–plant–atmospheric precipitation, precipitation plays the main controlling role. The main source of replenishment for alpine meadow plants is precipitation and alpine meltwater; the main source of replenishment for forest plants is soil water; and the plants in the arid foothills mainly use groundwater.
Roberto Velázquez-Ochoa, María Julia Ochoa-Izaguirre, and Martín Federico Soto-Jiménez
Biogeosciences, 19, 1–27,Short summary
Our research is the first approximation to understand the δ13C macroalgal variability in one of the most diverse marine ecosystems in the world, the Gulf of California. The life-form is the principal cause of δ13C macroalgal variability, mainly taxonomy. However, changes in habitat characteristics and environmental conditions also influence the δ13C macroalgal variability. The δ13C macroalgae is indicative of carbon concentration mechanisms and isotope discrimination during carbon assimilation.
Raquel F. Flynn, Thomas G. Bornman, Jessica M. Burger, Shantelle Smith, Kurt A. M. Spence, and Sarah E. Fawcett
Biogeosciences, 18, 6031–6059,Short summary
Biological activity in the shallow Weddell Sea affects the biogeochemistry of recently formed deep waters. To investigate the drivers of carbon and nutrient export, we measured rates of primary production and nitrogen uptake, characterized the phytoplankton community, and estimated nutrient depletion ratios across the under-sampled western Weddell Sea in mid-summer. Carbon export was highest at the ice shelves and was determined by a combination of physical, chemical, and biological factors.
Stéphanie H. M. Jacquet, Christian Tamburini, Marc Garel, Aurélie Dufour, France Van Vambeke, Frédéric A. C. Le Moigne, Nagib Bhairy, and Sophie Guasco
Biogeosciences, 18, 5891–5902,Short summary
We compared carbon remineralization rates (MRs) in the western and central Mediterranean Sea in late spring during the PEACETIME cruise, as assessed using the barium tracer. We reported higher and deeper (up to 1000 m depth) MRs in the western basin, potentially sustained by an additional particle export event driven by deep convection. The central basin is the site of a mosaic of blooming and non-blooming water masses and showed lower MRs that were restricted to the upper mesopelagic layer.
Shinsuke Kawagucci, Yohei Matsui, Akiko Makabe, Tatsuhiro Fukuba, Yuji Onishi, Takuro Nunoura, and Taichi Yokokawa
Biogeosciences, 18, 5351–5362,Short summary
Hydrogen and carbon isotope ratios of methane as well as the relevant biogeochemical parameters and microbial community compositions in hydrothermal plumes in the Okinawa Trough were observed. We succeeded in simultaneously determining hydrogen and carbon isotope fractionation factors associated with aerobic oxidation of methane in seawater (εH = 49.4 ± 5.0 ‰, εC = 5.2 ± 0.4 ‰) – the former being the first of its kind ever reported.
Nicolai Schleinkofer, David Evans, Max Wisshak, Janina Vanessa Büscher, Jens Fiebig, André Freiwald, Sven Härter, Horst R. Marschall, Silke Voigt, and Jacek Raddatz
Biogeosciences, 18, 4733–4753,Short summary
We have measured the chemical composition of the carbonate shells of the parasitic foraminifera Hyrrokkin sarcophaga in order to test if it is influenced by the host organism (bivalve or coral). We find that both the chemical and isotopic composition is influenced by the host organism. For example strontium is enriched in foraminifera that grew on corals, whose skeleton is built from aragonite, which is naturally enriched in strontium compared to the bivalves' calcite shell.
Lena Rohe, Traute-Heidi Anderson, Heinz Flessa, Anette Goeske, Dominika Lewicka-Szczebak, Nicole Wrage-Mönnig, and Reinhard Well
Biogeosciences, 18, 4629–4650,Short summary
This is the first experimental setup combining a complex set of methods (microbial inhibitors and isotopic approaches) to differentiate between N2O produced by fungi or bacteria during denitrification in three soils. Quantifying the fungal fraction with inhibitors was not successful due to large amounts of uninhibited N2O production. All successful methods suggested a small or missing fungal contribution. Artefacts occurring with microbial inhibition to determine N2O fluxes are discussed.
Inga Köhler, Raul E. Martinez, David Piatka, Achim J. Herrmann, Arianna Gallo, Michelle M. Gehringer, and Johannes A. C. Barth
Biogeosciences, 18, 4535–4548,Short summary
We investigated how high Fe(II) levels influence the O2 budget of a circum-neutral Fe(II)-rich spring and if a combined study of dissolved O (DO) and its isotopic composition can help assess this effect. We showed that dissolved Fe(II) can exert strong effects on the δ18ODO even though a constant supply of atmospheric O2 occurs. In the presence of photosynthesis, direct effects of Fe oxidation become masked. Critical Fe(II) concentrations indirectly control the DO by enhancing photosynthesis.
Owen A. Sherwood, Samuel H. Davin, Nadine Lehmann, Carolyn Buchwald, Evan N. Edinger, Moritz F. Lehmann, and Markus Kienast
Biogeosciences, 18, 4491–4510,Short summary
Pacific water flowing eastward through the Canadian Arctic plays an important role in redistributing nutrients to the northwest Atlantic Ocean. Using samples collected from northern Baffin Bay to the southern Labrador Shelf, we show that stable isotopic ratios in seawater nitrate reflect the fraction of Pacific to Atlantic water. These results provide a new framework for interpreting patterns of nitrogen isotopic variability recorded in modern and archival organic materials in the region.
Franziska Slotta, Lukas Wacker, Frank Riedel, Karl-Uwe Heußner, Kai Hartmann, and Gerhard Helle
Biogeosciences, 18, 3539–3564,Short summary
The African baobab is a challenging climate and environmental archive for its semi-arid habitat due to dating uncertainties and parenchyma-rich wood anatomy. Annually resolved F14C data of tree-ring cellulose (1941–2005) from a tree in Oman show the annual character of the baobab’s growth rings but were up to 8.8 % lower than expected for 1964–1967. Subseasonal δ13C and δ18O patterns reveal years with low average monsoon rain as well as heavy rainfall events from pre-monsoonal cyclones.
Peter M. J. Douglas, Emerald Stratigopoulos, Sanga Park, and Dawson Phan
Biogeosciences, 18, 3505–3527,Short summary
Hydrogen isotopes could be a useful tool to help resolve the geographic distribution of methane emissions from freshwater environments. We analyzed an expanded global dataset of freshwater methane hydrogen isotope ratios and found significant geographic variation linked to water isotopic composition. This geographic variability could be used to resolve changing methane fluxes from freshwater environments and provide more accurate estimates of the relative balance of global methane sources.
Veronica R. Rollinson, Julie Granger, Sydney C. Clark, Mackenzie L. Blanusa, Claudia P. Koerting, Jamie M. P. Vaudrey, Lija A. Treibergs, Holly C. Westbrook, Catherine M. Matassa, Meredith G. Hastings, and Craig R. Tobias
Biogeosciences, 18, 3421–3444,Short summary
We measured nutrients and the naturally occurring nitrogen (N) and oxygen (O) stable isotope ratios of nitrate discharged from a New England river over an annual cycle, to monitor N loading and identify dominant sources from the watershed. We uncovered a seasonality to loading and sources of N from the watershed. Seasonality in the nitrate isotope ratios also informed on N cycling, conforming to theoretical expectations of riverine nutrient cycling.
Petra Zahajská, Carolina Olid, Johanna Stadmark, Sherilyn C. Fritz, Sophie Opfergelt, and Daniel J. Conley
Biogeosciences, 18, 2325–2345,Short summary
The drivers of high accumulation of single-cell siliceous algae (diatoms) in a high-latitude lake have not been fully characterized before. We studied silicon cycling of the lake through water, radon, silicon, and stable silicon isotope balances. Results showed that groundwater brings 3 times more water and dissolved silica than the stream inlet. We demonstrate that groundwater discharge and low sediment deposition have driven the high diatom accumulation in the studied lake in the past century.
Yu-Te Hsieh, Walter Geibert, E. Malcolm S. Woodward, Neil J. Wyatt, Maeve C. Lohan, Eric P. Achterberg, and Gideon M. Henderson
Biogeosciences, 18, 1645–1671,Short summary
The South Atlantic near 40° S is one of the high-productivity and most dynamic nutrient regions in the oceans, but the sources and fluxes of trace elements (TEs) to this region remain unclear. This study investigates seawater Ra-228 and provides important constraints on ocean mixing and dissolved TE fluxes to this region. Vertical mixing is a more important source than aeolian or shelf inputs in this region, but particulate or winter deep-mixing inputs may be required to balance the TE budgets.
Zhongjie Yu and Emily M. Elliott
Biogeosciences, 18, 805–829,Short summary
In this study, we demonstrated distinct nitrogen isotope effects for nitric oxide (NO) production from major microbial and chemical NO sources in an agricultural soil. These results highlight characteristic bond-forming and breaking mechanisms associated with microbial and chemical NO production and implicate that simultaneous isotopic analyses of NO and nitrous oxide (N2O) can lead to unprecedented insights into the sources and processes controlling NO and N2O emissions from agricultural soils.
Daniel A. Frick, Rainer Remus, Michael Sommer, Jürgen Augustin, Danuta Kaczorek, and Friedhelm von Blanckenburg
Biogeosciences, 17, 6475–6490,Short summary
Silicon is taken up by some plants to increase structural stability and to develop stress resistance and is rejected by others. To explore the underlying mechanisms, we used the stable isotopes of silicon that shift in their relative abundance depending on the biochemical transformation involved. On species with a rejective (tomato, mustard) and active (wheat) uptake mechanism, grown in hydroculture, we found that the transport of silicic acid is controlled by the precipitation of biogenic opal.
Quentin Charbonnier, Julien Bouchez, Jérôme Gaillardet, and Éric Gayer
Biogeosciences, 17, 5989–6015,Short summary
The abundance and isotope composition of the trace metal barium (Ba) allows us to track and quantify nutrient cycling throughout the Amazon Basin. In particular, we show that the Ba biological fingerprint evolves from that of a strong net nutrient uptake in the mountainous area of the Andes towards efficient nutrient recycling on the plains of the Lower Amazon. Our study highlights the fact that the geochemical signature of rock-derived nutrients transported by the Amazon is scarred by life.
Ajinkya G. Deshpande, Thomas W. Boutton, Ayumi Hyodo, Charles W. Lafon, and Georgianne W. Moore
Biogeosciences, 17, 5639–5653,Short summary
Wetland forests in the southern USA are threatened by changing climate and human-induced pressures. We used tree ring widths and C isotopes as indicators of forest growth and physiological stress, respectively, and compared these to past climate data. We observed that vegetation growing in the drier patches is susceptible to stress, while vegetation growth and physiology in wetter patches is less sensitive to unfavorable environmental conditions, highlighting the importance of optimal wetness.
Dominika Lewicka-Szczebak, Maciej Piotr Lewicki, and Reinhard Well
Biogeosciences, 17, 5513–5537,Short summary
We present the first validation of N2O isotopic approaches for estimating N2O source pathways and N2O reduction. These approaches are widely used for tracing soil nitrogen cycling, but the results of these estimations are very uncertain. Here we report the results from parallel treatments allowing for precise validation of these approaches, and we propose the best strategies for results interpretation, including the new idea of an isotope model integrating three isotopic signatures of N2O.
Markus Raitzsch, Claire Rollion-Bard, Ingo Horn, Grit Steinhoefel, Albert Benthien, Klaus-Uwe Richter, Matthieu Buisson, Pascale Louvat, and Jelle Bijma
Biogeosciences, 17, 5365–5375,Short summary
The isotopic composition of boron in carbonate shells of marine unicellular organisms is a popular tool to estimate seawater pH. Usually, many shells need to be dissolved and measured for boron isotopes, but the information on their spatial distribution is lost. Here, we investigate two techniques that allow for measuring boron isotopes within single shells and show that they yield robust mean values but provide additional information on the heterogeneity within and between single shells.
Florian Einsiedl, Anja Wunderlich, Mathieu Sebilo, Ömer K. Coskun, William D. Orsi, and Bernhard Mayer
Biogeosciences, 17, 5149–5161,Short summary
Nitrate pollution of freshwaters and methane emissions into the atmosphere are crucial factors in deteriorating the quality of drinking water and in contributing to global climate change. Here, we report vertical concentration and stable isotope profiles of CH4, NO3-, NO2-, and NH4+ in the water column of Fohnsee (southern Bavaria, Germany) that may indicate linkages between nitrate-dependent anaerobic methane oxidation and the anaerobic oxidation of ammonium.
Ruifang C. Xie, Frédéric A. C. Le Moigne, Insa Rapp, Jan Lüdke, Beat Gasser, Marcus Dengler, Volker Liebetrau, and Eric P. Achterberg
Biogeosciences, 17, 4919–4936,Short summary
Thorium-234 (234Th) is widely used to study carbon fluxes from the surface ocean to depth. But few studies stress the relevance of oceanic advection and diffusion on the downward 234Th fluxes in nearshore environments. Our study in offshore Peru showed strong temporal variations in both the importance of physical processes on 234Th flux estimates and the oceanic residence time of 234Th, whereas salinity-derived seawater 238U activities accounted for up to 40 % errors in 234Th flux estimates.
Ralf A. Oeser and Friedhelm von Blanckenburg
Biogeosciences, 17, 4883–4917,Short summary
We present a novel strategy to decipher the relative impact of biogenic and abiotic drivers of weathering. We parameterized the nutrient fluxes in four ecosystems along a climate and vegetation gradient situated on the Chilean Coastal Cordillera. We investigated how nutrient demand by plants drives weathering. We found that the increase in biomass nutrient demand is accommodated by faster nutrient recycling rather than an increase in the weathering–release rates.
Tito Arosio, Malin M. Ziehmer, Kurt Nicolussi, Christian Schlüchter, and Markus Leuenberger
Biogeosciences, 17, 4871–4882,Short summary
Stable isotopes in tree-ring cellulose are tools for climatic reconstructions, but interpretation is challenging due to nonclimate trends. We analyzed the tree-age trends in tree-ring isotopes of deciduous larch and evergreen cembran pine. Samples covering the whole Holocene were collected at the tree line in the Alps. For cambial ages over 100 years, we prove the absence of age trends in δD, δ18O, and δ13C for both species. For lower cambial ages, trends differ for each isotope and species.
Yuyang He, Xiaobin Cao, and Huiming Bao
Biogeosciences, 17, 4785–4795,Short summary
Different carbon sites in a large organic molecule have different isotope compositions. Different carbon sites may not have the chance to exchange isotopes at all. The lack of appreciation of this notion might be blamed for an unsettled debate on the thermodynamic state of an organism. Here we demonstrate using minerals, N2O, and acetic acid that the dearth of exchange among different carbon sites renders them as independent as if they were different elements in organic molecules.
Felix M. Spielmann, Albin Hammerle, Florian Kitz, Katharina Gerdel, and Georg Wohlfahrt
Biogeosciences, 17, 4281–4295,Short summary
Carbonyl sulfide (COS) can be used as a proxy for plant photosynthesis on an ecosystem scale. However, the relationships between COS and CO2 fluxes and their dependence on daily to seasonal changes in environmental drivers are still poorly understood. We examined COS and CO2 ecosystem fluxes above an agriculturally used mountain grassland for 6 months. Harvesting of the grassland disturbed the otherwise stable COS-to-CO2 uptake ratio. We even found the canopy to release COS during those times.
Getachew Agmuas Adnew, Thijs L. Pons, Gerbrand Koren, Wouter Peters, and Thomas Röckmann
Biogeosciences, 17, 3903–3922,Short summary
We measured the effect of photosynthesis, the largest flux in the carbon cycle, on the triple oxygen isotope composition of atmospheric CO2 at the leaf level during gas exchange using three plant species. The main factors that limit the impact of land vegetation on the triple oxygen isotope composition of atmospheric CO2 are identified, characterized and discussed. The effect of photosynthesis on the isotopic composition of CO2 is commonly quantified as discrimination (ΔA).
Moritz Schroll, Frank Keppler, Markus Greule, Christian Eckhardt, Holger Zorn, and Katharina Lenhart
Biogeosciences, 17, 3891–3901,Short summary
Fungi have recently been identified to produce the greenhouse gas methane. Here, we investigated the stable carbon isotope values of methane produced by saprotrophic fungi. Our results show that stable isotope values of methane from fungi are dependent on the fungal species and the metabolized substrate. They cover a broad range and overlap with stable carbon isotope values of methane reported for methanogenic archaea, the thermogenic degradation of organic matter, and other eukaryotes.
Pranav Hirave, Guido L. B. Wiesenberg, Axel Birkholz, and Christine Alewell
Biogeosciences, 17, 2169–2180,Short summary
Sediment input into water bodies is a prominent threat to freshwater ecosystems. We tested the stability of tracers employed in freshwater sediment tracing based on compound-specific isotope analysis during early degradation in soil. While bulk δ13C values showed no stability, δ13C values of plant-derived fatty acids and n-alkanes were stably transferred to the soil without soil particle size dependency after an early degradation in organic horizons, thus indicating their suitability as tracers.
Caroline Thaler, Amandine Katz, Magali Bonifacie, Bénédicte Ménez, and Magali Ader
Biogeosciences, 17, 1731–1744,Short summary
Paleoenvironment reconstructions, retrieved from δ18O and Δ47 values measured in carbonate, are compromised when crystallization occurs in isotopic disequilibrium. We show that some paleoenvironmental information can still be retrieved from these paired disequilibrium Δ47 and δ18O values. The possibility of retrieving information on paleowaters, sediments' interstitial waters, or organisms' body water at the carbonate precipitation loci will help understand past Earth and life evolution.
Guillaume Humbert, Mathieu Sébilo, Justine Fiat, Longqi Lang, Ahlem Filali, Véronique Vaury, Mathieu Spérandio, and Anniet M. Laverman
Biogeosciences, 17, 979–993,Short summary
Mitigating emissions of the greenhouse gas N2O requires understanding of the relative contribution of its producing processes in response to environmental variables. We show, using isotopic analysis, that N2O emissions from a nitrifying system were sensitive to oxygenation, temperature and NH4+ concentrations with nitrite reduction being the main N2O source. Temperature appears to be the main control on N2O production, due to its dissimilar effects on ammonium and nitrite oxidizing activities.
Oguz Yigiterhan, Ebrahim Mohd Al-Ansari, Alex Nelson, Mohamed Alaa Abdel-Moati, Jesse Turner, Hamood Abdulla Alsaadi, Barbara Paul, Ibrahim Abdullatif Al-Maslamani, Mehsin Abdulla Al-Ansi Al-Yafei, and James W. Murray
Biogeosciences, 17, 381–404,Short summary
We analyze net-tow samples of plankton and associated particulate matter from the Exclusive Economic Zone, Qatar, Arabian Gulf, using net tows with mesh sizes of 50 and 200 μm to examine the composition of plankton populations. We also focus on the role and composition of the atmospheric dust, representative of terrigenous material, deposited in the Gulf. We concluded that Al, Fe, Cr, Co, Mn, Ni, Pb, and Li are of dust origin and As, Cd, Cu, Mo, Zn, and Ca are of anthropogenic/biogenic origin.
Clare Woulds, James B. Bell, Adrian G. Glover, Steven Bouillon, and Louise S. Brown
Biogeosciences, 17, 1–12,Short summary
Sedimented hydrothermal vents occur where heated, mineral-rich (hydrothermal) water seeps through seafloor sediments. They host chemosynthetic microbes, which use chemical energy to fix dissolved carbon dioxide into sugars (chemosynthesis). We conducted carbon tracing experiments, and observed chemosynthesis at both vent and non-vent sites. Thus, chemosynthesis occurred over a much larger area than expected, suggesting it is more widespread than previously thought.
Cara C. Manning, Rachel H. R. Stanley, David P. Nicholson, Brice Loose, Ann Lovely, Peter Schlosser, and Bruce G. Hatcher
Biogeosciences, 16, 3351–3376,Short summary
We measured rates of biological activity and gas exchange in a Canadian estuary during ice melt. We quantified gas exchange using inert, deliberately released tracers and found that the gas transfer rate at > 90 % ice cover was 6 % of the rate for nearly ice-free conditions. We measured oxygen concentration and isotopic composition and used the data to detect changes in the rates of photosynthesis and respiration (autotrophy and heterotrophy) as the ice melted.
Marlène Lavrieux, Axel Birkholz, Katrin Meusburger, Guido L. B. Wiesenberg, Adrian Gilli, Christian Stamm, and Christine Alewell
Biogeosciences, 16, 2131–2146,Short summary
A fingerprinting approach using compound-specific stable isotopes was applied to a lake sediment core to reconstruct erosion processes over the past 150 years in a Swiss catchment. Even though the reconstruction of land use and eutrophication history was successful, the observation of comparatively low δ13C values of plant-derived fatty acids in the sediment suggests their alteration within the lake. Thus, their use as a tool for source attribution in sediment cores needs further investigation.
Luciana A. Pereira, Roberto V. Santos, Marília Hauser, Fabrice Duponchelle, Fernando Carvajal, Christophe Pecheyran, Sylvain Bérail, and Marc Pouilly
Biogeosciences, 16, 1781–1797,Short summary
This study presents the first step for a chemical origin certification of pirarucu fishery in the Amazon. A preliminary isotopic tool to improve the actual tracking system integrates ecological, social, and economic aspects of Amazon dynamics. The geographic origin validation of farmed and wild fishes contributes to environmental and social practices, secures food and income to communities, helps manage endangered species, reinforces aquaculture, and combats illegal fisheries.
Sarah Conrad, Johan Ingri, Johan Gelting, Fredrik Nordblad, Emma Engström, Ilia Rodushkin, Per S. Andersson, Don Porcelli, Örjan Gustafsson, Igor Semiletov, and Björn Öhlander
Biogeosciences, 16, 1305–1319,Short summary
Iron analysis of the particulate, colloidal, and truly dissolved fractions along the Lena River freshwater plume showed that the particulate iron dominates close to the coast. Over 99 % particulate and about 90 % colloidal iron were lost, while the truly dissolved phase was almost constant. Iron isotopes suggest that the shelf acts as a sink for particles and colloids with negative iron isotope values, while colloids with positive iron isotope values travel further out into the Arctic Ocean.
Elizabeth Verhoeven, Matti Barthel, Longfei Yu, Luisella Celi, Daniel Said-Pullicino, Steven Sleutel, Dominika Lewicka-Szczebak, Johan Six, and Charlotte Decock
Biogeosciences, 16, 383–408,Short summary
This study utilized state-of-the-art measurements of nitrogen isotopes to evaluate nitrogen cycling and to assess the biological sources of the potent greenhouse gas, N2O, in response to water-saving practices in rice systems. Water-saving practices did emit more N2O, and high N2O production had a lower 15N isotope signature. Modeling and visual interpretation indicate that these emissions mostly came from denitrification or nitrifier denitrification, controlled upstream by nitrification rates.
Feifei Deng, Gideon M. Henderson, Maxi Castrillejo, Fiz F. Perez, and Reiner Steinfeldt
Biogeosciences, 15, 7299–7313,Short summary
To better use Pa / Th to reconstruct deep water ventilation rate, we assessed controls on 230Th and 231Pa in the northern North Atlantic. With extended optimum multi-parameter analysis and CFC-based water-mass age, we found the imprint of young overflow water on Th and Pa and enhanced scavenging near the seafloor. A significantly higher advective loss of Pa to the south relative to Th in the Atlantic was estimated, supporting the use of Pa / Th for assessing basin-scale meridional transport.
Anne L. Morée, Jörg Schwinger, and Christoph Heinze
Biogeosciences, 15, 7205–7223,Short summary
Changes in the distribution of the carbon isotope 13C can be used to study the climate system if the governing processes (ocean circulation and biogeochemistry) are understood. We show the Southern Ocean importance for the global 13C distribution and that changes in 13C can be strongly influenced by biogeochemistry. Interpretation of 13C as a proxy for climate signals needs to take into account the effects of changes in biogeochemistry in addition to changes in ocean circulation.
Douglas G. Russell, Wei Wen Wong, and Perran L. M. Cook
Biogeosciences, 15, 7225–7234,Short summary
Nitrogen is an important nutrient in marine environments and is continually converted from one form to another. One way these processes can be investigated is by looking at the ratio of the 15N and 14N stable isotopes of different nitrogen-containing compounds. To date few studies have compared these ratios in seagrass beds, their associated sediments and the porewater NH4+ pool. The strong relationship between these nitrogen pools suggests that nitrogen is tightly recycled within seagrass beds.
Bharat Rastogi, Max Berkelhammer, Sonia Wharton, Mary E. Whelan, Frederick C. Meinzer, David Noone, and Christopher J. Still
Biogeosciences, 15, 7127–7139,Short summary
Carbonyl sulfide (OCS) has gained prominence as an independent tracer for gross primary productivity, which is usually modelled by partitioning net CO2 fluxes. Here, we present a simple empirical model for estimating ecosystem-scale OCS fluxes for a temperate old-growth forest and find that OCS sink strength scales with independently estimated CO2 uptake and is sensitive to the the fraction of downwelling diffuse light. We also examine the response of OCS and CO2 fluxes to sequential heat waves.
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δ13C in plants is a sensitive long-term indicator of physiological acclimatization. The present study suggests that precipitation change and increasing atmospheric N deposition have little impact on δ13C of H. ammodendron, a dominant plant in central Asian deserts, but affect its gas exchange. In addition, this study shows that δ13C of H. ammodendron could not indicate its water use efficiency (WUE), suggesting that whether δ13C of C4 plants indicates WUE is species-specific.
δ13C in plants is a sensitive long-term indicator of physiological acclimatization. The present...