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Greenhouse Gas Measurements Over a 144KM Open Path in the Canary Islands
A new technique for the satellite remote sensing of greenhouse gases in the atmosphere via the absorption of short-wave infrared laser signals transmitted between counter-rotating satellites in low earth orbit has recently been proposed; this would enable the acquisition of a stable, global set of altitude-resolved concentration measurements. We present the first ground-based…
Old-growth CO2 flux measurements reveal high sensitivity to climate anomalies across seasonal, annual and decadal time scales
The traditional hypothesis that old-growth forests are carbon neutral is under debate as recent studies show evidence of net carbon sequestration. Here, we present a decade (1998–2008) of carbon dioxide, water and energy fluxes from an old-growth stand in the American Pacific Northwest to identify ecosystem-level responses to climate variability, including teleconnection patterns.…
Contribution of Urine and Dung Patches from Grazing Sheep to Methane and Carbon Dioxide Fluxes in an Inner Mongolian Desert Grassland
The effects of sheep urine and dung patches on methane (CH4) and carbon dioxide (C[O.sub.2]) fluxes were investigated during the summer-autumn in 2010, to evaluate their contribution to climate change in a desert grassland in Inner Mongolia, China. Results indicate that the cumulative C[H.sub.4] emissions for dung patches, urine patches and control plots were -0.076, -0.084, and -0.…
Tracing groundwater recharge sources in a mountain–plain transitional area using stable isotopes and hydrochemistry
Mountain–plain transitional landscapes are especially important as groundwater recharge zones. In this study, the oxygen and hydrogen stable isotopic composition (δ18O and δD) of water and hydrochemical information were employed to quantify contribution ratios of different sources of groundwater recharge in the Ashikaga area…
Geochemistry of a continental site of serpentinization, the Tablelands Ophiolite, Gros Morne National Park: A Mars analogue
The presence of aqueously altered, olivine-rich rocks along with carbonate on Mars suggest that serpentinization may have occurred in the past and may be occurring presently in the subsurface, and possibly contributing methane (CH4) to the martian atmosphere. Serpentinization, the hydration of olivine in ultramafic rocks, yields ultra-basic fluids (pH ⩾…
Model-Based Interpolation, Prediction, and Approximation
Model-based interpolation, prediction, and approximation are contingent on the choice of model: since multiple alternative models typically can reasonably be entertained for each of these tasks, and the results are correspondingly varied, this often is a considerable source of uncertainty. Several statistical methods are illustrated that can be used to assess the contribution that…
Accurate measurements of carbon monoxide in humid air using the cavity ring-down spectroscopy (CRDS) technique
Accurate measurements of carbon monoxide (CO) in humid air have been made usingthe cavity ring-down spectroscopy (CRDS) technique. The measurements of CO molefractions are determined from the strength of its spectral absorption in the near infraredregion (∼ 1.57 µm) after removing interferences from adjacent carbon dioxide (CO25 )and water vapor (H2O) absorption lines. Water correction…
Oxygen isotope ratios in the shell of Mytilus edulis: archives of glacier meltwater in Greenland?
Melting of the Greenland Ice Sheet (GrIS) is accelerating and will contribute signifi-cantly to global sea level rise during the 21st century. Instrumental data on GrIS melting only cover the last few decades, and proxy data extending our knowledge into5 the past are vital for validating models predicting the influence of ongoing climatechange. We investigated a potential meltwater proxy in…
Hydrogeochemical and isotopic evidence for trans-formational flow in a sedimentary basin: implications for CO2 storage
Deep saline aquifers are considered as the most promising option for geologic disposal of CO2. One of the main concerns, however, is the integrity of the caprocks between and above the storage formations. Here, a hydrogeochemical and isotopic investigation is presented, using ionic chemistry, stable isotopes (δ18O, δ2H and 87Sr/86…
Ice-core net snow accumulation and seasonal snow chemistry at a temperate-glacier site: Mount Waddington, southwest British Columbia, Canada
A 141 m-long ice core was recovered from Combatant Col (51.385°N, 125.258°W, 3000 m a.s.l.), Mount Waddington, Coast Mountains, British Columbia, Canada. Records of black carbon, dust, lead, and water stable-isotopes demonstrate that unambiguous seasonality is preserved throughout the core, despite summer surface snowmelt and temperate ice. High accumulation…
First continuous shipboard d18O and dD measurements in sea water by diffusion sampling—cavity ring-down spectrometry
Combined measurements of salinity and the oxygen/hydrogen stable isotope composition of marine
waters can characterise processes such as freshwater mixing, evaporation, precipitation and sea-ice formation.
However, stable isotope data with high spatial and temporal resolution are necessary for a detailed understanding
of mixed water bodies with multiple inputs. So far analysis of…
Evaluation of a Cavity Ring-Down Spectrometer for In-Situ Observations of 13CO2
With the emergence of wide-spread application of cavity ring-down spectrometers (CRDS) to monitor δ13C in atmospheric CO2 there is a growing need to ensure well calibrated measurements. We characterized a cavity ring-down spectrometer system used for continuous in-situ monitoring of atmospheric 13CO…
Timing and Magnitude of C Partitioning Through a Young Loblolly Pine (Pinus taeda L.) Stand Using 13C Labeling and Shade Treatments
The dynamics of rapid changes in carbon (C) partitioning within forest ecosystems are not well understood, which limitsimprovement of mechanistic models of C cycling. Our objective was to inform model processes by describing relationshipsbetween C partitioning and accessible environmental or physiological measurements, with a special emphasis on short-termC flux through a forest ecosystem.…
Integrated assessment on groundwater nitrate by unsaturated zone probing and aquifer sampling with environmental tracers
By employing chemical and isotopic tracers (15N and 18O in NO3−), we investigated the main processes controlling nitrate distribution in the unsaturated zone and aquifer. Soil water was extracted from two soil cores drilled in a typical agricultural cropping area of the North China Plain (NCP),…
Discrepancies Between Isotope Ratio Infrared Spectroscopy and Isotope Ratio Mass Spectrometry for the Stable Isotope Analysis of Plant and Soil Waters
The use of isotope ratio infrared spectroscopy (IRIS) for the stable hydrogen and oxygen isotopeanalysis of water is increasing. While IRIS has many advantages over traditional isotope ratio massspectrometry (IRMS), it may also be prone to errors that do not impact upon IRMS analyses. Ofparticular concern is the potential for contaminants in the water sample to interfere with…
Continuous Low-Maintenance CO2/CH4/H2O Measurements at the Zotino Tall Tower Observatory (ZOTTO) in Central Siberia
To monitor the continental carbon cycle, a fullyautomated low maintenance measurement system is installedat the Zotino Tall Tower Observatory in Central Siberia(ZOTTO, 60◦480N, 89◦210E) since April 2009. A cavity ring-down spectroscopy (CRDS) analyzer continuouslymeasures carbon dioxide (CO2) and methane (CH4) fromsix heights up to 301 m a.g.l. Buffer volumes in each airline remove short…
Measurement of fossil fuel derived carbon dioxide and other anthropogenic trace gases above Sacramento, California in Spring 2009
Direct quantification of fossil fuel CO2(CO2ff) in atmospheric samples can be used toexamine several carbon cycle and air quality questions. We collected in-situ CO2, CO,and CH4 measurements and flask samples in the boundary layer and free troposphere5 over Sacramento, California, USA, during two aircraft flights over and downwind ofthis urban area during spring of 2009. The flask samples were…
Aircraft-Based Measurements of the Carbon Footprint of Indianapolis
The quantification of greenhouse gas emissions requireshigh precision measurements made with high spatial resolution.Here we describe measurements of carbon dioxide (CO2)and methane(CH4) conducted using Purdue University’s AirborneLaboratory for Atmospheric Research (ALAR), aimed at thequantification of the “footprints” for these greenhouse gasesfor Indianapolis, IN. A cavity ring-down…
Secondary Organic Aerosol Formation from Gasoline Vehicle Emissions in a New Mobile Environmental Reaction Chamber
We present a new mobile environmental reaction chamber for the simulation of the atmospheric aging of aerosols from different emissions sources without limitation from the instruments or facilities available at any single site. The chamber can be mounted on a trailer for transport to host facilities or for mobile measurements. Photochemistry is simulated using a set of 40 UV lights (…
Rapid Transformation of Inorganic to Organic and Plant-Available Phosphorous in Soils of a Glacier Forefield
Chemical weathering of rocks or sediments is extremely important for the generation of soils, for the evolution of landscape, and as a main source of inorganic nutrients for plant growth and therefore for life. Temporal trends in weathering mechanisms, plant succession and nutrients availability in cold environments can be successfully studied in soil chronosequences along a glacier…
Tracing Atmospheric Nitrate in Groundwater Using Triple Oxygen Isotopes: Evaluation Based on Bottled Drinking Water
The stable isotopic compositions of nitrate dissolved in 49 types of bottled drinkingwater collected worldwide were determined, to trace the fate of atmospheric nitrate(NO−3 atm) that had been deposited into subaerial ecosystems, using the17O anomalies(∆175 O) of nitrate as tracers. The use of bottled water enables collection of groundwaterrecharged at natural, background watersheds. The…
Mixing of Rhone River Water in Lake Geneva (Switzerland-France) Inferred from Stable Hydrogen and Oxygen Isotope Profiles
Depth profiles were sampled at different locations throughout Lake Geneva on a monthly and seasonal basis over the course of two years and analyzed for their stable hydrogen and oxygen isotope compositions. The isotopic composition indicates an isotopic stratification in the metalimnion during summer and fall. This is related to mixing of Rhône River water, which in summer is…
Positive and negative impacts of five Austrian gravel pit lakes on groundwater quality
Groundwater-fed gravel pit lakes (GPLs) affect the biological, organic, and inorganic parameters of inflowing groundwater through combined effects of bank filtration at the inflow, reactions within the lake, and bank filtration at the outflow. GPLs result from wet dredging for sand and gravel and may conflict with groundwater protection programs by removing the protective soil…
Eemian interglacial reconstructed from a Greenland folded ice core
Efforts to extract a Greenland ice core with a complete record of the Eemian interglacial (130,000 to 115,000 years ago) have until now been unsuccessful. The response of the Greenland ice sheet to the warmer-than-present climate of the Eemian has thus remained unclear. Here we present the new North Greenland Eemian Ice Drilling (‘NEEM’) ice core and show only a modest ice-sheet…
Dual-Chamber Measurements of δ13C of Soil-Respired CO2 partitioned using a field-based three end-member model
The contribution of old soil C (SOM) to total soil respiration (RS) in forest has been a crucial topic in global change research, but remains uncertain. Isotopic methods, such as natural variations in carbon isotope composition (δ13C) of soil respiration, are more frequently being applied, and show promise in separating heterotrophic and autotrophic…
Using cavity ringdown spectroscopy for continuous monitoring of δ13C(CO2) and ƒCO2 in the surface ocean
The role of the global surface ocean as a source and sink for atmospheric carbon dioxide and the flux strengths between the ocean and the atmosphere can be quantified by measuring the fugacity of CO2 (ƒCO2) as well as the dissolved inorganic carbon (DIC) concentration and its isotopic composition in surface seawater. In this work, the potential of…
Precise and accurate δ13C analysis of rock samples using Flash Combustion–Cavity Ring Down Laser Spectroscopy
The ratio of 13C to 12C in marine sedimentary rocks holds important clues to the evolution of the carbon cycle through Earth history. Isotopic analyses are traditionally carried out using isotope ratio mass spectrometry (IRMS), but this technique is labor-intensive, expensive and requires expert know-how. Here, we measure …
Quantifying sources of methane using light alkanes in the Los Angeles basin, California
Methane (CH4), carbon dioxide (CO2), carbon monoxide (CO), and C2–C5 alkanes were measured throughout the Los Angeles (L.A.) basin in May and June 2010. We use these data to show that the emission ratios of CH4/CO and CH4/CO2…
Interannual variation of water isotopologues at Vostok indicates a contribution from stratospheric water vapor
Combined measurements of water isotopologues of a snow pit at Vostok over the past 60 y reveal a unique signature that cannot be explained only by climatic features as usually done. Comparisons of the data using a general circulation model and a simpler isotopic distillation model reveal a stratospheric signature in the 17O-excess record at Vostok. Our data and theoretical considerations…
Optimization of instrument setup and post-run corrections for oxygen and hydrogen stable isotope measurements of water by isotope ratio infrared spectroscopy (IRIS)
Light stable isotope analyses of hydrogen (2H/1H) and oxygen (18O/16O) of water are used in many terrestrial and marine aquatic studies. The advantage of using stable isotope ratios is that water molecules serve as ubiquitous and already present natural tracers. Within recent years, these analyses have been revolutionized by the development of new isotope ratio laser spectroscopy (…
Calibration of TCCON column-averaged CO2: the first aircraft campaign over European TCCON sites
The Total Carbon Column Observing Network (TCCON) is a ground-based network of Fourier Transform Spectrometer (FTS) sites around the globe, where the column abundances of CO2, CH4, N2O, CO and O2 are measured. CO2 is constrained with a precision better than 5 0.25%. To achieve a similarly high accuracy, calibration to World…
A depth-controlled tracer technique measures vertical, horizontal and temporal patterns of water use by trees and grasses in a subtropical savanna
- As described in the two-layer hypothesis, woody plants are often assumed to use deep soils to avoid competition with grasses. Yet the direct measurements of root activity needed to test this hypothesis are rare.
- Here, we injected deuterated water into four soil depths, at four times of year, to measure the vertical and horizontal location of water uptake by trees and…
Origin of sulfur and mode of gypsum formation in central Iraqi soils
The δ18O and δD values of gypsum crystallization water together with δ18O and δ34S of sulfates were used as reliable techniques to study source of sulfur and mode of gypsum formation in selected central Iraqi soils. Six representative pedons on different geologic units were studied. The slope of 3.2 for δ18O and δD plot of gypsum crystallization water showed that evaporation was the major…
Ice-vapor equilibrium fractionation factor of hydrogen and oxygen isotopes: Experimental investigations and implications for stable water isotope studies
RATIONALE
The equilibrium fractionation factors govern the relative change in the isotopic composition during phase transitions of water. The commonly used results, which were published more than 40 years ago, are limited to a minimum temperature of –33°C. This limits the reliability in cold regions. With recent…
Characterizing moisture exchange between the Hawaiian convective boundary layer and free troposphere using stable isotopes in water
The subtropical convective boundary layer (CBL) plays a critical role in climate by regulating the vertical exchange of moisture, energy, trace gases, and pollutants between the ocean surface and free troposphere. Yet bulk features of this exchange are poorly constrained in climate models. To improve our understanding of moisture transport between the boundary layer and free troposphere,…
Quantification of long-term wastewater fluxes at the surface water/groundwater-interface: An integrative model perspective using stable isotopes and acesulfame
The suitability of acesulfame to trace wastewater-related surface water fluxes from streams into the hyporheic and riparian zones over long-term periods was investigated. The transport behavior of acesulfame was compared with the transport of water stable isotopes (δ18O or δ2H). A calibrated model based on a joint inversion of temperature, acesulfame, and piezometric pressure heads was…
Dissolved organic carbon loss from Yedoma permafrost amplified by ice wedge thaw
Pleistocene Yedoma permafrost contains nearly a third of all organic matter (OM) stored in circum-arctic permafrost and is characterized by the presence of massive ice wedges. Due to its rapid formation by sediment accumulation and subsequent frozen storage, Yedoma OM is relatively well preserved and highly biologically available (biolabile) upon thaw. A better understanding of the…
Monthly d18O, dD and Cl- characteristics of precipitation in the Ndop plan, Northwest Cameroon: Baseline data
Knowledge of stable isotopes and chemical tracers in meteoric water has been used as a valuable tool in various environmental studies. A systematic monthly sampling of precipitation, in the Ndop plain, was carried out to generate basic data on δ18, δD and Cl−, determine their seasonal variations and controlling factors to be used as baseline data in hydrological and climatological studies.…
A synthesis of hydrogen isotope variability and its hydrological significance at the Qinghai–Tibetan Plateau
Hydrogen isotope ratios of sedimentary biomarkers are known to record the climatic variability in terrestrial and marine environments. However, there is still a lack of calibration studies that can quantitatively retrace the driving forces, especially at the Tibetan Plateau. Here, we elaborate the actual influence of environmental parameters such as temperature, evapotranspiration, salinity…
Vegetation induced changes in the stable isotope composition of near surface humidity
Obtaining the d-excess parameter from oxygen and hydrogen stable isotope composition of meteoric waters has the potential power to reconstruct changes in atmospheric water pools (e,g. sources, origins and overall balance) and the climatic conditions that prevail during surface evaporation. Recently, plant and ecosystem scientists turned their attention using d-…
Estimation of soil water evaporative loss after tillage operation using the stable isotope technique
Application of stable isotopes in soil studies has improved quantitative evaluation of evaporation and other hydrological processes in soil. This study was carried out to determine the effect of tillage on evaporative loss of water from the soil. Zero tillage and conventional tillage were compared. Suction tubes were installed for soil water collection at the depths 0.15, 0.50, and 1.0 m by…
Water isotopic variability in response to mesoscale convective system over the tropical ocean
In tropical regions, the empirical negative relationship between the isotopic content of precipitation and rainfall amount, known as the 'amount effect', has been used as a rationale for paleo-hydroclimate reconstruction from isotope records. However, there is still no comprehensive physical explanation for this empirical effect. Here, we reconsider the well-known amount effect using newly…
Root niche partitioning among grasses, saplings, and trees measured using a tracer technique
Niche partitioning of resources by plants is believed to be a fundamental aspect of plant coexistence and biogeochemical cycles; however, measurements of the timing and location of resource use are often lacking because of the difficulties of belowground research. To measure niche partitioning of soil water by grasses, planted saplings, and trees in a mesic savanna (Kruger National Park,…
A test of the advection-condensation model for subtropical water vapor using stable isotopologue observations from Mauna Loa Observatory, Hawaii
Subtropical humidity plays a critical role in the radiative balance of the planet, and there is a need for adequate description of the controls on water vapor distributions. This study tests whether an advection-condensation model, combined with Rayleigh distillation, can describe observed humidity and water vapor isotope ratios of the subtropical free troposphere. A field campaign, from 9…
The nocturnal water cycle in an open-canopy forest
The movement of moisture into, out-of, and within forest ecosystems is modulated by feedbacks that stem from processes which couple plants, soil, and the atmosphere. While an understanding of these processes has been gleaned from Eddy Covariance techniques, the reliability of the method suffers at night because of weak turbulence. During the summer of 2011, continuous profiles of the…
A multitower measurement network estimate of California’s methane emissions
We present an analysis of methane (CH4) emissions using atmospheric observations from five sites in California’s Central Valley across different seasons (September 2010 to June 2011). CH4 emissions for spatial regions and source sectors are estimated by comparing measured CH4 mixing ratios with transport model (…
Guano-derived d13C-based paleo-hydroclimate record from Gaura cu Musca Cave, SW Romania
The δ13C values of 23 unevenly spaced guano samples from a 17-cm long clay sediment profile in Gaura cu Musca Cave (GM), in SW Romania, made it possible to preliminarily characterize the Medieval Warm Period summer hydroclimate regime. The beginning of the sequence (AD 990) was rather wet for more than a century, before becoming progressively drier. After a brief, yet distinct wet period…
Spatial and Temporal Variation of Stable Isotopes in Precipitation across Costa Rica: An Analysis of Historic GNIP Records
The location of Costa Rica on the Central American Isthmus creates unique microclimate systems that receive moisture inputs directly from the Caribbean Sea and the Pacific Ocean. In Costa Rica, stable isotope monitoring was conducted by the International Atomic Energy Agency and the World Meteorological Association as part of the worldwide effort entitled Global Network of Isotopes in…
Performance assessment of a cavity ring-down laser spectrometer: achieving better precision and accuracy in the measurement of δ18O and δ2H in liquid water samples
The development of new isotopic laser-based analyzers currently represents a clear alternative to conventional isotope ratio mass spectrometers. However, this analytical technique also suffers some disadvantages such as the memory effect, problems related to the overall stability of the equipment and other issues associated with the injection system, essentially regarding the syringe's…