Origins of Groundwater Inferred from Isotopic Patterns of the Badain Jaran Desert, Northwestern China
There are many viewpoints about the sources of groundwater in the Badain Jaran Desert (BJD), such as precipitation and snowmelt from the Qilian Mountains (the upper reaches [UR] of the Heihe River Basin [HRB]) and precipitation from the BJD and the Yabulai Mountains.
Hydrogen isotope ratios of lacustrine sedimentary n-alkanes as proxies of tropical African hydrology: Insights from a calibration transect across Cameroon
Hydrogen isotope values (δD) of sedimentary aquatic and terrestrial lipid biomarkers, originating from algae, bacteria, and leaf wax, have been used to record isotopic properties of ancient source water (i.e., precipitation and/or lake water) in several mid- and high-latitude lacustrine environments. In the tropics, however, where both processes associated with isotope fractionation in the hydrologic system and vegetation strongly differ from those at higher latitudes, calibration studies for this proxy are not yet available.
Properties of air mass mixing and humidity in the subtropics from measurements of the D/H isotope ratio of water vapor at the Mauna Loa Observatory
Water vapor in the subtropical troposphere plays an important role in the radiative balance, the distribution of precipitation, and the chemistry of the Earth's atmosphere. Measurements of the water vapor mixing ratio paired with stable isotope ratios provide unique information on transport processes and moisture sources that is not available with mixing ratio data alone. Measurements of the D/H isotope ratio of water vapor from Mauna Loa Observatory over 4 weeks in October–November 2008 were used to identify components of the regional hydrological cycle.
Late Glacial temperature and precipitation changes in the lowland Neotropics by tandem measurement of δ18O in biogenic carbonate and gypsum hydration water
Exploring Geographic Origins at Cahuachi using Stable Isotopic Analysis of Archaeological Human Tissues and Modern Environmental Waters
In this study, we used oxygen- and hydrogen-isotope data from human bone (δ18O) and modern environmental water samples (δ18O and δD) to investigate geographic origins of individuals buried at Cahuachi, a ceremonial centre in the Nasca region of Peru (c.AD1-1000). Our objective was to characterise the natural variation in water stable isotopic composition in the Rio Grande de Nasca drainage, and then to use these data to better infer place of origin for 30 adults interred at Cahuachi.
Positive feedbacks amplify rates of woody encroachment in mesic tallgrass prairie
Over the last century, many grasslands worldwide have transitioned from a graminoid to atree/shrub-dominated state in a short period of time, a phenomenon referred to as woody encroachment.Positive feedbacks and bi-stability are thought to be important drivers of woody encroachment, but there islittle empirical evidence to suggest that positive feedbacks accelerate the woody encroachment of mesicgrasslands. In mesic tallgrass prairie, shrub establishment does not directly facilitate seedlingestablishment.
Water isotopic ratios from a continuously melted ice core sample
A new technique for on-line high resolution isotopic analysis of liquid water, tailored for ice core studies is presented. We built an interface between a Wavelength Scanned Cavity Ring Down Spectrometer (WS-CRDS) purchased from Picarro Inc. and a Continuous Flow Analysis (CFA) system. The system offers the possibility to perform simultaneuous water isotopic analysis of δ18O and δD on a continuous stream of liquid water as generated from a continuously melted ice rod.
Large amplitude spatial and temporal gradients in atmospheric boundary layer CO2 mole fractions detected with a tower-based network in the U.S. upper Midwest
his study presents observations of atmospheric boundary layer CO2 mole fraction from a nine-tower regional network deployed during the North American Carbon Program's Mid-Continent Intensive (MCI) during 2007–2009. The MCI region is largely agricultural, with well-documented carbon exchange available via agricultural inventories. By combining vegetation maps and tower footprints, we show the fractional influence of corn, soy, grass, and forest biomes varies widely across the MCI.
Hydrocarbon emissions characterization in the Colorado Front Range: A pilot study
The multispecies analysis of daily air samples collected at the NOAA BoulderAtmospheric Observatory (BAO) in Weld County in northeastern Colorado since 2007shows highly correlated alkane enhancements caused by a regionally distributed mixof sources in the Denver-Julesburg Basin. To further characterize the emissions of methaneand non-methane hydrocarbons (propane, n-butane, i-pentane, n-pentane and benzene)around BAO, a pilot study involving automobile-based surveys was carried out duringthe summer of 2008.
A 1-year long δ18O record of water vapor in Niamey (Niger) reveals insightful atmospheric processes at different timescales
We present a 1-year long representative δ18O record of water vapor (δ18Ov) in Niamey (Niger) using the Wavelength Scanned-Cavity Ring Down Spectroscopy (WS-CRDS). We explore how local and regional atmospheric processes influence δ18Ov variability from seasonal to diurnal scale.
Analysis and fit of surface CO2 concentrations at a rural site
Purpose
The impact of CO2 urban plume in a rural area was investigated by concentrations recorded near surface.
Methods
CO2 dry concentrations at three levels near surface were recorded for about 8 months at a rural site. Daily cycles were obtained and directional analysis was made with percentiles. Several functions were used to fit background and plume concentrations and the goodness of fit was evaluated with different statistics, which were also compared.
Gravel pit lake ecosystems reduce nitrate and phosphate concentrations in the outflowing groundwater
Gravel excavation often bears conflicts with the use of drinking water as under-water-table mining can directly impact groundwater quality downstream of the open gravel pit lake due to exposure of the groundwater aquifer to the atmosphere and to human activities. To assess this potential impact of GPLs on groundwater, we assessed the mass balance for nitrate (NO3) and phosphate (PO4) and whole-ecosystem metabolism of five post-excavation GPLs in Austria. GPLs differed in both age and residence time of lake water.
Submicron particles influenced by mixed biogenic and anthropogenic emissions: high-resolution aerosol mass spectrometry results from the Carbonaceous Aerosols and Radiative Effects Study (CARES)
The Carbonaceous Aerosols and Radiative Effects Study (CARES) took place in the Sacramento Valley of California in summer 2010. We present results obtained at Cool, CA, the T1 site of the project (~40 km downwind of urban emissions from Sacramento), where we deployed an Aerodyne high resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) in parallel with complementary instrumentation to characterize the sources and processes of submicron particles (PM1).
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 -0.114 g/[m.sup.2] and these were net C[H.sub.4] sinks during the measured period.
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.
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 contributions to RS.
Continuous analysis of δ<sup>18</sup>O and δD values of water by diffusion sampling cavity ring-down spectrometry: a novel sampling device for unattended field monitoring of precipitation, ground and surface waters
A novel sampling device suitable for continuous, unattended field monitoring of rapid isotopic changes in environmental waters is described. The device utilises diffusion through porous PTFE tubing to deliver water vapour continuously from a liquid water source for analysis of δ18O and δD values by Cavity Ring-Down Spectrometry (CRDS). Separation of the analysed water vapour from non-volatile dissolved and particulate contaminants in the liquid sample minimises spectral interferences associated with CRDS analyses of many aqueous samples.
New Experimental Approaches to Measuring Plant-Extracted Waters
The recent development of a field deployable water isotope analyzer using CRDS technology was used to directly measure the vapor isotopes in real time and at multiple heights above the crop canopy. This technique was coupled with additional samples gathered using conventional techniques and a new xylem water extracting apparatus developed by the IAEA.
Real-Time Field-Based Water Vapor Isotope Measurements with a CRDS Analyzer: Probing Cropland Evapotranspiration
Describes a field campaign wherein a Picarro water isotope analyzer was used to measure isotopes in water vapor over a corn field in China for the purpose of studying evapotranspiration. The Picarro sampled vapor along with a cold trap sampling system and the real-time Picarro data was compared to offline analysis of the trapped vapor.
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.
Civil Aircraft for the Regular Investigation of the Atmosphere Based on an Instrument Container (CARIBIC) Observations of CO2 Uptake During the Indian Summer Monsoon
The Drivers of the CH4 Seasonal Cycle in the Arctic and What Long-Term Observations of CH4 Imply About Trends in Arctic CH4 Fluxes
Quantification of Anthropogenic Emissions from an Urban Region: First Results of Time-Integrated Flask Samples from the Indianapolis Flux (INFLUX)
Long-Term Methane Observations at the Global Atmosphere Watch Site Jungfraujoch with Gas Chromatography and Cavity Ringdown Spectroscopy
Greenhouse Gas and Ozone Measurements from Aircraft in Alaska 2009 - 2011
Correcting for Methane Interferences on δ2H and δ18O Measurements in Pore Water Using H2O(liquid)–H2O(vapor) Equilibration Laser Spectroscopy
Cavity ring-down spectroscopy (CRDS) is a new and evolving technology that shows great promise for isotopic δ(18)O and δ(2)H analyses of pore water from equilibrated headspace H(2)O vapor from environmental and geologic cores. We show that naturally occurring levels of CH(4) can seriously interfere with CRDS spectra, leading to erroneous δ(18)O and δ(2)H results for water. We created a new CRDS correction algorithm to account for CH(4) concentrations typically observed in subsurface and anaerobic environments, such as ground waters or lake bottom sediments.
Modeling soil metabolic processes using isotopologue pairs of position-specific 13C-labeled glucose and pyruvate
We used metabolic tracers and modeling to analyze the response of soil metabolism to a sudden temperature change from 4 to 20 °C. We hypothesized that intact soil microbial communities would exhibit shifts in pentose phosphate pathway and glycolysis activity as observed for individual microorganisms in pure culture, and that increased maintenance respiration at higher temperature would result in greater energy production and reduced carbon use efficiency (CUE). Two hours after temperature increase, respiration increased almost 10-fold.
δ18O anchoring to VPDB: calcite digestion with 18O-adjusted ortho-phosphoric acid
For anchoring CO2 isotopic measurements on the δ18OVPD-CO2 scale, the primary reference material (NBS 19 calcite) needs to be digested using concentrated ortho-phosphoric acid. During this procedure, great care must be taken to ensure that the isotopic composition of the liberated gas is accurate. Apart from controlling the reaction temperature to ±0.1°C, the potential for oxygen isotope exchange between the produced CO2 and water must be kept to a minimum. The water is usually assumed to reside on the walls in the headspace of the reaction vessel.
Effect of temperature on metabolic activity of intact microbial communities: Evidence for altered metabolic pathway activity but not for increased maintenance respiration and reduced carbon use efficiency
We used metabolic tracers and modeling to analyze the response of soil metabolism to a sudden temperature change from 4 to 20 °C. We hypothesized that intact soil microbial communities would exhibit shifts in pentose phosphate pathway and glycolysis activity as observed for individual microorganisms in pure culture, and that increased maintenance respiration at higher temperature would result in greater energy production and reduced carbon use efficiency (CUE). Two hours after temperature increase, respiration increased almost 10-fold.
Probing carbon flux patterns through soil microbial metabolic networks using parallel position-specific tracer labeling
In order to study controls on metabolic processes in soils, we determined the dynamics of 13CO2 production from two position-specific 13C-labeled pyruvate isotopologues in the presence and absence of glucose, succinate, pine, and legume leaf litter, and under anaerobic conditions. We also compared 13CO2 production in soils along a semiarid substrate age gradient in Arizona.
High Precision 13C/12C Measurement of Dissolved Carbon Using a Transportable Cavity Ring-Down Spectrophotometer System
The world’s first continuous flow isotopic TIC/DOC-CRDS measurements are reported here with remarkable achieved precisions. A measurement precision of the isotopic ratio in the range of 0.2 ‰ to 0.4 ‰ was achieved in minutes of measurement time. Such precision readily distinguishes the isotopic DIC and DOC signatures from a set of three different streamwater samples collected from various sites in Northern California.
Investigations of Deep-Sea Hydrothermal Samples for Isotopic Composition and Interfering Compounds Using CRDS
Hydrothermal fluids from two vent sites along the East Scotia Ridge, E2 and E9, were analyzed for their hydrogen and oxygen isotopic values using a Picarro L1115-i CRDS. The fluids display varying salinity, sulfate and hydrogen sulfide content. None of the samples analyzed in this work showed any signs of spectroscopic interference. Isotopic values of the fluids were combined with salinity, magnesium and silica measurements to determine the possible role of magmatic inputs and phase separation.
Measuring CO, CH4, CO2 & H2O Simultaneously Using New CRDS Technology to Characterize Urban Plumes & the Well-Mixed Atmosphere
Cavity Ring-Down spectroscopy is becoming a gold standard for atmospheric monitoring. High sensitivity and precision coupled with low drift characteristics ensure optimal operation even in remote field stations or on aircraft and ships. However, current platforms have been limited to two or three species simultaneous observation.
An Acetylene Tracer-Based Approach to Quantifying Methane Emissions from Distributed Sources Using Cavity Ring-Down Spectroscopy
The quantification of fugitive methane emissions from extended sources such as landfills is problematic due to the high temporal variability and spatial heterogeneity of the emission. Additionally, the relationship between the emission rate and the gas concentration at a given location is dependent on the meteorological conditions and local topography, preventing accurate quantification of the emission rate.
Hi-Resolution Observations of Stable Oxygen and Hydrogen Isotopes of Water and Water Vapor in California
The regulation of Earth’s climate and its ability to sustain life are critically linked to water as it exists in all three of its phases (gas, liquid, and solid). Earth’s water cycle, its movement between the hydrosphere, biosphere, and the atmosphere, and how it undergoes phase changes, is incredibly complex. While we continue to gain insight into the water cycle, there remains considerable uncertainty in predicting the impacts of future climate change on fresh water supplies and the welfare of life on our planet.
Real-Time Field-Based Water Vapor Isotope Measurements with a CRDS Analyzer: Probing Cropland Evapotranspiration
While stable isotope techniques have been previously applied to partition evapotranspiration (ET) fluxes in crops, it has only recently become possible to take in situ, long-term, continuous (every 10 seconds) measurements of stable water vapor isotopologues.
Toward continuous monitoring of seawater 13CO2/12CO2 isotope ratio and pCO2: Performance of cavity ringdown spectroscopy and gas matrix effects
Greenhouse Gas and Ozone Measurements from Aircraft in Alaska 2009 - 2011
Presentation Description:
The NOAA ESRL GMD Carbon Cycle and Greenhouse Gases Group’s aircraft network consists of 18 sites, mostly in North America, that conduct bi-weekly flask sampling over given locations to altitudes of 8000 m above sea level (masl). Most sites sample 12 flasks during an altitude profile, and through collaboration with GMD’s Ozone group, many conduct continuous ozone measurements as well. In March 2009, a new site in Alaska (site code ACG) was added to our network, through a collaborative effort with the U.S. Coast Guard (USCG).
Rapid detection and characterization of surface CO2 leakage through the real-time measurement of δ13 C signatures in CO2 flux from the ground
A portable stable carbon isotope ratio analyzer for carbon dioxide, based on wavelength scanned cavity ringdown spectroscopy, has been used to detect, locate, and characterize an intentional leakage of CO2 from an underground pipeline at the ZERT experimental facility in Bozeman, Montana. Rapid (1 h) walking surveys of the 100 m x 100 m site surrounding the pipeline were collected using this mobile, real-time instrument.
Real-Time Tracking of CO2 Injected into a Subsurface Coal Fire through High-Frequency Measurements of the 13CO2 Signature
Atmospheric monitoring of the CO2 CRC Otway Project and lessons for large scale CO2 storage projects
Monitoring is essential for the approval and control of geological storage of carbon dioxide and to judge the effectiveness of the technology in mitigating CO2 emissions and climate change. We present a strategy for monitoring the atmosphere in the vicinity of a geological storage project that is designed to detect and quantify potential emissions. The strategy includes measurements of CO2, CO2 fluxes and tracers, combined with model simulations of atmospheric dispersion and ecosystem CO2 fluxes.
LIAISON™: Fully-Automated Universal Interface for Bulk 13C High-Precision Isotope Analysis using Cavity Ring-Down Spectroscopy
Describes application and function of a the LIAISON, a new Picarro universal interface for high throughput analysis.
Continuous Flow—Cavity Ring-Down Spectroscopy: A Powerful Tool for Food Origin Analysis and Adulteration Detection
Describes use and methods for stable isotope-based food adulteration testing using Cavity Ring-Down Spectrometry.
Capturing small-scale variations of water isotopes in ambient air and natural waters of California: Results of field measurements using Cavity Ring-Down Spectroscopy
Describes field work conducted with Picarro water isotope analyzer for both water vapor and liquid water samples.
A Mid-IR, Cavity Ring-Down Spectrometer for Continuous Trace N2O and Nitrogen Isotope Measurements
Describes recent developments in CRDS instrumentation in the mid-infrared spectral region for applications using N2O isotopologue and trace concentration measurements.
Demonstration of High-Throughput Water Isotopologue Measurements Using Cavity Ring-Down Spectroscopy
Describes the flexibility of Picarro's fast water isotope analyzer for applications requiring very short sample-to-sample measurement times and shows data taken in lab and field measurements.
Compound Specific Isotope Analysis of Carbon using Cavity Ring-Down Spectrometry
Describes recent developments in GC-C-CRDS-based instrumentation applied to isotope measurements in large molecules.
An Acetylene Tracer-Based Approach to Quantifying Methane Emissions from Distributed Sources Using Cavity Ring-Down Spectroscopy
Describes a newly-developed analyzer for tracer-based measurements and shows results from field work using such a system.
A Mid-IR, Wavelength-Scanned, Cavity Ring-Down Spectrometer for Continuous Trace N2O and Nitrogen Isotope Measurements
Describes results from a Picarro N2O analyzer based in the mid-infrared spectral region.
Vertical Profiles of Greenhouse Gas Concentrations via Airborne Measurements.
Describes results of laboratory testing and field campaigns with Picarro's flight-ready greenhouse gas analyzer.