Soil and vadose zone profiles are used as an archive of changes in groundwater recharge and water quality following changes in land use in an area of the Loess Plateau of China. A typical rain-fed loess-terrace agriculture region in Hequan, Guyuan, is taken as an example, and multiple tracers (chloride mass balance, stable isotopes, tritium and water chemistry) are used to examine…
The lapse rate of water isotopes is used in the study of the hydrologic cycle as well as in the estimation of uplift of the Tibetan Plateau. The greater elevation contrast in the southern Himalayas allows for a detailed discussion about this lapse rate. We analyze variations of δ 18O in precipitation and river water between 1320 m and 6700 m…
Attributing observed CO2 variations to human or natural cause is critical to deducing and tracking emissions from observations. We have used in situ CO2, CO, and planetary boundary layer height (PBLH) measurements recorded during the CalNex-LA (CARB et al., 2008) ground campaign of 15 May–15 June 2010, in Pasadena, CA, to deduce the diurnally varying anthropogenic…
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…
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…
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-…
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…
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…
There is a close relationship between surface water and groundwater in semi-arid and arid areas of China, and thus researching on the interactions of them is of importance for reasonable water resources development. This paper took Bulang River basin as case study, analysis and discussion were conducted to water chemistry and isotopes tests results of water samples. The results show that…
The repeatability, reproducibility and accuracy of the direct measurement of δ(D) and δ(18O) isotopes in water samples were evaluated using Cavity Ring-Down Spectrometry, and values comparable with the Isotopic Ratio Mass Spectrometry were obtained. Memory effect correction was negligible after five successive injections, and the time for each sample…
Stable carbon and oxygen isotopic compositions (_13C and _18O) of benthicforaminiferal carbonate shells have been used to reconstruct past bottom water environments.However, the details of factors controlling the isotopic disequilibrium be-5 tween the shells and the surrounding bottom seawater (the vital effect) are still ambiguous.In this study, we analyzed…
Hydrogen isotope ratios in lipids derived from mangroves have the potential to be used for paleohydrologic reconstructions and could serve as a much needed tool for establishing past climate variability in the tropics. We assessed the effect of salinity on the apparent fractionation factor, αa, between mangrove derived n-alkanes and their source…
Isotope records of atmospheric CH4 can be used to infer changes in the biochemistry of CH4. One factor limiting quantitative estimates of changes in the biogeochemistry of CH4 are the uncertainties of the isotope measurements due to the lack of a unique isotope reference gas, certified for 13C-CH4 or 2 5 H-CH4. We…
Tunable diode laser absorption (TDL) and cavity ring-down spectroscopic (CRDS) sensors for atmospheric carbon dioxide were co-deployed during summer and fall of 2010 in field and laboratory conditions at Los Alamos National Laboratory. Both sensors were characterized for accuracy and precision for ambient carbon dioxide measurements at ground level and compared using both laboratory…
The experiment was conducted at twelve grazing plots denoting four treatments defined along a grazing gradient with three replications: non-grazing (0 sheep/ha, NG), light grazing (0.75 sheep/ha, LG), moderate grazing (1.50 sheep/ha, MG) and heavy grazing (2.25 sheep/ha, HG). Using an automatic cavity ring-down spectrophotometer, we measured CH4 fluxes from March 1 to April 29 in…
Questions of mobility, settlement pattern, and their relation to economic organization and resource use are central to ongoing work in central-western Argentina. Here we analyze geographic patterns in the distribution of 178 human bone carbonate δ18O samples, 46 human tooth enamel carbonate δ18O samples, and 48 water δ18…
In preparation for the routine deployment of the Earth Networks greenhouse gas monitoring network, we have designed and tested a simple method for drying ambient airto below 0.2 % mole fraction H2O using a Nafion dryer. The inlet was designed for usewith a Picarro model G2301 cavity ring down spectrometer (CRDS) CO2/CH45 /H2O analyzer. The analyzer measures water vapor mixing ratio at the…
This article reports the first application of coupled total organic carbon cavity ring-down spectroscopy (TOC-CRDS) for the analysis of the δ13C signature of dissolved organic carbon (DOC) in freshwater samples. DOC represents a major, dynamic component of the global carbon cycle. The export of DOC from soils into rivers and groundwaters may be highly climate…
Within the project MUSICA (MUlti-platform remote Sensing of Isotopologues for investigating the Cycle of Atmospheric water), long-term tropospheric water vapour isotopologues data records are provided for ten globally distributed ground-based mid-infrared remote sensing stations of the NDACC (Network for the Detection of Atmospheric Composition Change). We present…
N2 fixation by moss-associated cyanobacteria plays an important role in the nitrogen cycling of terrestrial ecosystems. Recent studies have mainly focused on boreal ecosystems; little is known about such association in other ecosystems. Moss-associated cyanobacteria are subject to rapid changes (hourly or less) in environmental conditions that may affect N2…
The 2010 Arctic Mars Analog Svalbard Expedition (AMASE) investigated two distinct geologic settings on Svalbard, using methodologies and techniques to be deployed on Mars Science Laboratory (MSL). AMASE-related research comprises both analyses conducted during the expedition and further analyses of collected samples using laboratory facilities at a variety of institutions. The Sample…
Continuous real-time analysis, at 30 sec intervals, of precipitation at an Australian tropical location revealed extreme and rapidly changing δ18O and δD values related to variations in moisture source areas, transport paths and precipitation histories. The range of δ18O (−19.6 to +2.6 ‰) and δD (−140 to +13 ‰) values from 5948 measurements of nine…
We examined potential interferences from water vapor and atmospheric backgroundgases (N2, O2, and Ar), and biases by isotopologues of target species, on accuratemeasurement of atmospheric CO2 and CH4 by means of wavelength-scanned cavity5 ring-down spectroscopy (WS-CRDS). Variations in the composition of the backgroundgas substantially impacted the CO2 and CH4 measurements: the measured…
The NorthGRIP ice core chronology GICC05modelext is composed of the annual-layercounted GICC05 chronology to 60 kyr before 2000 AD (b2k), and an ice flow model dating the deepest part of the ice core to 123 kyr b2k. Determination of annual strata in ice5 beyond 60 kyr b2k has been challenged by the thinning of annual layers to < 1 cm andthe appearance of microfolds in some early glacial…
Long-term time series of the atmospheric composition are essential for environmental research and thus require compatible, multi-decadal monitoring activities. However,the current data quality objectives of the World Meteorological Organization (WMO) for5 carbon monoxide (CO) in the atmosphere are very challenging to meet with the measurement techniques that have been used until recently.…
The D/H isotope ratio is used to attribute boundary layer humidity changes to the set of contributing fluxes for a case following a snowstorm in which a snow pack of about 10 cm vanished. Profiles of H2O and CO2 mixing ratio, D/H isotope ratio, and several thermodynamic properties were measured from the surface to 300 m every 15 min during four winter days near…
A one hour integrated flask sampling system to collect air in automated NOAA/ESRL12-flask packages is described. The integrating compressor system uses a mass flowcontroller to regulate the flow of air through a 15 l volume, thus providing a mixture of air5 collected over an hour-long period. By beginning with a high flow rate of 3800 standardliters per minute and gradually decreasing the flow…
In this paper we report vertical profiles of CO2 measured with a cavity ring-down spectrometer (CRDS, Picarro, Inc., 2301-m) on a research aircraft from near ground level to 8 km above mean sea level (a.m.s.l.). The airborne platform employed in this study is an Alpha Jet aircraft operated from NASA Ames Research Center. Flights were undertaken to…
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…
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.…
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.…
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…
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 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 (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…
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…
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…
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…
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…
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…
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.…
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),…
The repeatability, reproducibility and accuracy of the direct measurement of δ(D) and δ(18O) isotopes inwater samples were evaluated using Cavity Ring-Down Spectrometry, and values comparable with the Isotopic Ratio Mass Spectrometry were obtained. Memory effect correction was negligible after five successive injections, and the time for each sample analysis was approximately 70 minutes.…
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…
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…
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…
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…
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 (…
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…
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