Isotopic tracing of leachate percolation from municipal solid waste dump sites to groundwater in diverse climatic zones of India.

Groundwater resources in tropical regions are largely dependent on recharge by rainwater infiltration through soil layers with variable time. However, the rainwater infiltration through soil is a serious concern in urban tropics where it interacts with landfills at the dumpsites, potentially contaminating adjoining groundwater. In this study, the stable isotopic compositions of oxygen and hydrogen (δO and δH, respectively) in groundwater and leachates, adjoining municipal dumpsites in urban tropics (Bangalore, Kolkata and Durgapur located in diverse rainfall zonation of India), were analyzed to investigate their recharge sources and trace the possible mixing of leachate contaminants under three diverse climatology.

New constraints of terrestrial and oceanic global gross primary productions from the triple oxygen isotopic composition of atmospheric CO and O.

Representations of the changing global carbon cycle under climatic and environmental perturbations require highly detailed accounting of all atmosphere and biosphere exchange. These fluxes remain unsatisfactory, as a consequence of only having data with limited spatiotemporal coverage and precision, which restrict accurate assessments. Through the nature of intimate coupling of global carbon and oxygen cycles via O and CO and their unique triple oxygen isotope compositions in the biosphere and atmosphere, greater insight is available.

Seasonal Variations of Solar-Induced Fluorescence, Precipitation, and Carbon Dioxide Over the Amazon.

Previous studies suggested that the Amazon, the largest rainforest on Earth, changes from a CO sink to a CO source during the dry/fire season. However, the biospheric contributions to atmospheric CO are not well understood during the two main seasons, the dry/fire season and the wet season. In this article, we utilize Orbiting Carbon Observatory 2 (OCO-2) Solar-Induced Fluorescence (SIF) to explore photosynthetic activity during the different seasons.

Characteristics of tree growth in mountain areas of central China: insights from isotopic compositions and satellite-derived indices.

Leaf nitrogen (N) status and stable isotope ratios of carbon (C) and nitrogen (N) were used to study environmental factors that control mountain individuals of trees, a coniferous species endemic and endangered in China. From May to September 2016, we carried out observations at four different altitude locations extending southeast of Daba Mountain in western Hubei Province. Needle-shaped leaf C was positively correlated with needle N and C content calculated from the needle area (N and C content), needle N, needle mass, and leaf mass per area (LMA), respectively.

Isotopic assessment of soil NO emission from a sub-tropical agricultural soil under varying N-inputs.

Nitrogen fertilizers result in high crop productivity but also enhance the emission of NO, an environmentally harmful greenhouse gas. Only approximately a half of the applied nitrogen is utilized by crops and the rest is either vaporized, leached, or lost as NO, NO and N via soil microbial activity. Thus, improving the nitrogen use efficiency of cropping systems has become a global concern.

Role of Vehicular Catalytic Converter Temperature in Emission of Pollutants: An Assessment Based on Isotopic Analysis of CO and NO.

Vehicular catalytic converters are used to regulate, reduce, and convert toxic and environmentally unfriendly compounds in exhaust gases into relatively inert and less harmful chemical species. The efficiency, however, is largely affected by the operating temperature of the converter which is set by the hot exhaust gas released from the combustion chamber. A major gas released during combustion is CO, and its multiply substituted isotopocule, namely, COO, provides a window of opportunity to probe directly the effective temperature of the converter in operation.

Variable thermoregulation of Late Cretaceous dinosaurs inferred by clumped isotope analysis of fossilized eggshell carbonates.

The thermal physiology of non-avian dinosaurs, especially the endothermic/ectothermic nature of their metabolism, inferred indirectly using body mass, biophysical modelling, bone histology and growth rate, has long been a matter of debate. Clumped isotope thermometry, based on the thermodynamically driven preference of C-O bond in carbonate minerals of fossilized eggshells, yields temperature of egg formation in the oviduct and can delineate the nature of thermoregulation of some extinct dinosaur taxa. In the present study, the clumped isotope thermometry was applied to the eggshells of a few species of modern birds and reptiles to show that it is possible to obtain the body temperatures of these species in most of the cases.

Utilization of ΔO for nitrate dynamics in a subtropical freshwater reservoir.

Feitsui Reservoir, a freshwater body in Taiwan with minimal anthropogenic stress, meets the water demand for the population of more than five million living in Taipei city. In view of the biogeochemical processes controlling the long-term trophic status of this socio-economically and ecologically important aquatic system, probing the nitrogen cycle and its dynamics is essential. Here, we monitored the concentration and stable isotopic compositions (δN, δO, and ΔO) of nitrate in the Feitsui Reservoir and in the atmospheric wet deposition at intervals of 1-2 weeks for a year, along with measurements of environmental data such as chlorophyll a, dissolved oxygen, and community respiration.

Ab initio quantum chemical studies of isotopic fractionation during acid digestion reaction of dolomite for clumped isotope application.

Rationale: In 'clumped isotope paleothermometry' carbonates are reacted with anhydrous phosphoric acid to extract CO that carries the isotopic signature of the reacting carbonates, and the amount of clumping in the product CO is measured. Previous theoretical models for determining clumped isotopic fractionation in product CO during acid digestion of carbonates are independent of the cations present in the carbonate lattice. Hence further study is required to understand the cationic effect.

A new perspective of probing the level of pollution in the megacity Delhi affected by crop residue burning using the triple oxygen isotope technique in atmospheric CO.

Air quality in the megacity Delhi is affected not only by local emissions but also by pollutants from crop residue burning in the surrounding areas of the city, particularly the rice straw burning in the post monsoon season. As a major burning product, gaseous CO, which is rather inert in the polluted atmosphere, provides an alternative solution to characterize the impact of biomass burning from a new perspective that other common tracers such as particulate matters are limited because of their physical and chemical reactiveness. Here, we report conventional ([CO], δC, and δO) and unconventional (ΔO) isotope data for CO collected at Connaught Place (CP), a core area in the megacity Delhi, and two surrounding remote regions during a field campaign in October 18-20, 2017.

Sulfur isotope analysis for representative regional background atmospheric aerosols collected at Mt. Lulin, Taiwan.

Air pollution resulted from fossil fuel burning has been an environmental issue in developing countries in Asia. Sulfur-bearing compounds, in particular, are species that are regulated and monitored routinely. To assess how the species affect at local and global scales, regional background level has to be defined.

Isotopic compositions of ground ice in near-surface permafrost in relation to vegetation and microtopography at the Taiga-Tundra boundary in the Indigirka River lowlands, northeastern Siberia.

The warming trend in the Arctic region is expected to cause drastic changes including permafrost degradation and vegetation shifts. We investigated the spatial distribution of ice content and stable isotopic compositions of water in near-surface permafrost down to a depth of 1 m in the Indigirka River lowlands of northeastern Siberia to examine how the permafrost conditions control vegetation and microtopography in the Taiga-Tundra boundary ecosystem. The gravimetric water content (GWC) in the frozen soil layer was significantly higher at microtopographically high elevations with growing larch trees (i.

Global 3-D Simulations of the Triple Oxygen Isotope Signature ΔO in Atmospheric CO.

The triple oxygen isotope signature ΔO in atmospheric CO, also known as its "O excess," has been proposed as a tracer for gross primary production (the gross uptake of CO by vegetation through photosynthesis). We present the first global 3-D model simulations for ΔO in atmospheric CO together with a detailed model description and sensitivity analyses. In our 3-D model framework we include the stratospheric source of ΔO in CO and the surface sinks from vegetation, soils, ocean, biomass burning, and fossil fuel combustion.

Distribution of CO in Western Pacific, Studied Using Isotope Data Made in Taiwan, OCO-2 Satellite Retrievals, and CarbonTracker Products.

To assess sources and processes that affect the variability of CO at local to regional scales, we have analyzed the mixing ratio [CO] and stable isotopic compositions (δC and δO) of atmospheric CO for three years (2014-2016) in urban and sub-urban areas in Taipei, Taiwan. The data are compared with those from some background sites, viz., Lulin, Mauna Loa, and Minamitorishima, to evaluate how local emissions affect CO level regionally.

A global database of water vapor isotopes measured with high temporal resolution infrared laser spectroscopy.

The isotopic composition of water vapour provides integrated perspectives on the hydrological histories of air masses and has been widely used for tracing physical processes in hydrological and climatic studies. Over the last two decades, the infrared laser spectroscopy technique has been used to measure the isotopic composition of water vapour near the Earth's surface. Here, we have assembled a global database of high temporal resolution stable water vapour isotope ratios (δO and δD) observed using this measurement technique.

Oxygen isotope anomaly in tropospheric CO and implications for CO residence time in the atmosphere and gross primary productivity.

The abundance variations of near surface atmospheric CO isotopologues (primarily OCO, OCO, OCO, and OCO) represent an integrated signal from anthropogenic/biogeochemical processes, including fossil fuel burning, biospheric photosynthesis and respiration, hydrospheric isotope exchange with water, and stratospheric photochemistry. Oxygen isotopes, in particular, are affected by the carbon and water cycles. Being a useful tracer that directly probes governing processes in CO biogeochemical cycles, ΔO (=ln(1 + δO) - 0.

Identification of Anthropogenic CO Using Triple Oxygen and Clumped Isotopes.

Quantification of contributions from various sources of CO is important for understanding the atmospheric CO budget. Considering the number and diversity of sources and sinks, the widely used proxies such as concentration and conventional isotopic compositions (δC and δO) are not always sufficient to fully constrain the CO budget. Additional constraints may help in understanding the mechanisms of CO production and consumption.

An improved method of high-precision determination of Δ(17)O of CO2 by catalyzed exchange with O2 using hot platinum.

Rationale: CO2 and O2 can exchange their oxygen isotopes rapidly in the presence of hot (~670 °C) platinum and this has led to a method for determining the δ(17)O value of a CO2 sample. We have improved the method to achieve a precision of 0.008 ‰ (1-σ standard deviation) in the determination of δ(17)O values.

Development of a multicopter-carried whole air sampling apparatus and its applications in environmental studies.

To advance the capabilities of probing chemical composition aloft, we designed a lightweight remote-controlled whole air sampling component (WASC) and integrated it into a multicopter drone with agile maneuverability to perform aerial whole air sampling. A field mission hovering over an exhaust shaft of a roadway tunnel to collect air samples was performed to demonstrate the applicability of the multicopter-carried WASC apparatus. Ten aerial air samples surrounding the shaft vent were collected by the multicopter-carried WASC.

Oxygen anomaly in near surface carbon dioxide reveals deep stratospheric intrusion.

Stratosphere-troposphere exchange could be enhanced by tropopause folding, linked to variability in the subtropical jet stream. Relevant to tropospheric biogeochemistry is irreversible transport from the stratosphere, associated with deep intrusions. Here, oxygen anomalies in near surface air CO2 are used to study the irreversible transport from the stratosphere, where the triple oxygen isotopes of CO2 are distinct from those originating from the Earth's surface.

A new feature in the internal heavy isotope distribution in ozone.

Ozone produced by discharge or photolysis of oxygen has unusually heavy isotopic composition ((18)O/(16)O and (17)O/(16)O ratio) which does not follow normal mass fractionation rule: δ(17)O ∼ 0.52(*)δ(18)O, expressed as an anomaly Δ(17)O = δ(17)O - 0.52(*)δ(18)O.

Interlaboratory assessment of nitrous oxide isotopomer analysis by isotope ratio mass spectrometry and laser spectroscopy: current status and perspectives.

Rationale: In recent years, research and applications of the N2O site-specific nitrogen isotope composition have advanced, reflecting awareness of the contribution of N2O to the anthropogenic greenhouse effect, and leading to significant progress in instrument development. Further dissemination of N2O isotopomer analysis, however, is hampered by a lack of internationally agreed gaseous N2O reference materials and an uncertain compatibility of different laboratories and analytical techniques.

Methods: In a first comparison approach, eleven laboratories were each provided with N2O at tropospheric mole fractions (target gas T) and two reference gases (REF1 and REF2).

Oxygen isotope exchange between O2 and CO2 over hot platinum: an innovative technique for measuring Δ17O in CO2.

The isotopic composition of carbon dioxide provides a powerful tool and has been widely used for constraining the sources and sinks of atmospheric CO2. In this work, we demonstrate a simple, rapid, and clean way for measuring the triple oxygen isotope ratio of carbon dioxide with high precision. The method depends on isotope exchange between O2 and CO2 in the presence of platinum at high temperature and allows rapid measurement of Δ(17)O of CO2.

Midlatitude atmospheric OH response to the most recent 11-y solar cycle.

The hydroxyl radical (OH) plays an important role in middle atmospheric photochemistry, particularly in ozone (O(3)) chemistry. Because it is mainly produced through photolysis and has a short chemical lifetime, OH is expected to show rapid responses to solar forcing [e.g.

An improved CeO2 method for high-precision measurements of 17O/16O ratios for atmospheric carbon dioxide.

Rationale: The oxygen isotopic composition of carbon dioxide originating at the Earth's surface is modified in the stratosphere by interaction with ozone which has anomalous oxygen isotope ratio (Δ(17)O = 1000 * ln(1 + δ(17)O/1000) - 0.522 * 1000 * ln (1 + δ(18)O/1000) >0). The inherited anomaly provides a powerful tracer for studying biogeochemical cycles involving CO(2).