Variation in stable carbon and oxygen isotopes of individual benthic foraminifera: tracers for quantifying the vital effect
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 analysis was approximately 70 minutes.
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 surface water in Bulang River basin mainly relies on precipitation recharge, partially on groundwater recharge, the hydrochemistry type of surface water is mainly Ca-HCO3 with low salinity.
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 and ambient field data.
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.
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 2010 and March 2 to April 27 in 2011.
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.
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 water for Avicennia marina (gray mangrove) specimens collected along a 28 PSU salinity gradient in the Brisbane River Estuary.
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 component of observed CO2 in the megacity of Los Angeles (LA).
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 elevations in the southern Himalayas, and calculate the specific lapse rate of water δ 18O.
Variations of stable water isotopes in water vapour have become measurable at a measurement frequency of about 1 Hz in recent years using novel laser spectroscopic techniques. This enables us to perform continuous measurements for process-based investigations of the atmospheric water cycle at the time scales relevant for synoptic meteorology. An important prerequisite for the interpretation of data from automated field measurements lasting for several weeks or months is a detailed knowledge about instrument properties and the sources of measurement uncertainty.
The suite of measurement methods available to characterize fluxes between groundwater and surface water is rapidly growing. However, there are few studies that examine approaches to design of field investigations that include multiple methods. We propose that performing field measurements in a spatially telescoping sequence improves measurement flexibility and accounts for nested heterogeneities while still allowing for parsimonious experimental design.
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 δ18O samples from throughout the Andean Cordillera and Monte Desert and evaluate their implications for prehistoric mobility and economy.
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 groundwater recharge mechanisms and to evaluate soil water chloride as an archive for recharge rate and water quality.
The Amazon River is a huge network of long tributaries, and little is known about the headwaters. Here we present a study of one wet tropical Amazon forest side, and one dry and cold Atiplano plateau, originating from the same cordillera. The aim is to see how this difference affects the water characteristics.
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. This study provides the longest, continuous record of old-growth eddy flux data to date.
Background. The diffusion of high-performance analytical technology has opened prospects for breath diagnosis as a non-invasive diagnostic tool. In this study, ion mobility spectrometry (IMS) and cavity ring-down spectroscopy (CRDS) techniques were used to analyse ammonia gas (NH3) in real-time in breath from patients undergoing haemodialysis (HD) treatment and any correlation with blood urea nitrogen (BUN) levels and Kt/V were investigated.
The mechanisms allowing the rapid release of stored water to streams are poorly understood. Here we use a tile drained field site to combine naturally structured soils at the hillslope scale with the advantage of at least partly controlled lower boundary conditions. We performed a series of three irrigation experiments combining hydrometric measurements with stable isotope and bromide tracers to better understand macropore-matrix interactions and stored water release processes at the hillslope scale.
Quantifying the processes that control dissolved inorganic carbon (DIC) dynamics in aquatic systems is essential for progress in ecosystem carbon budgeting. The development of a methodology that allows high-resolution temporal data collection over prolonged periods is essential and is described in this study.
We developed a method to measure in situ the isotopic composition of liquid water with minimal supervision and, most important, with a temporal resolution of less than a minute. For this purpose a microporous hydrophobic membrane contactor (Membrana) was combined with an isotope laser spectrometer (Picarro). The contactor, originally designed for degassing liquids, was used with N2 as a carrier gas in order to transform a small fraction of liquid water to water vapor.
The goal of this study is to determine how H2O and HDO measurements in water vapor can be used to detect and diagnose biases in the representation of processes controlling tropospheric humidity in atmospheric general circulation models (GCMs). We analyze a large number of isotopic data sets (four satellite, sixteen ground-based remote-sensing, five surface in situ and three aircraft data sets) that are sensitive to different altitudes throughout the free troposphere.
The Neogene Guantao formation in the Beitang sag in the Bohai Bay Basin (BBB) of North China, a Mesozoic–Cenozoic sedimentary basin of continental origin, has been chosen as a candidate for a pilot field test of CO2 sequestration. Hydrogeological and geochemical investigations have been carried out to assess its suitability, taking advantage of many existing geothermal wells drilled to 2000 m or greater depths.
oncern exists about the suitability of laser spectroscopic instruments for the measurement of the (18)O/(16)O and (2)H/(1)H values of liquid samples other than pure water. It is possible to derive erroneous isotope values due to optical interference by certain organic compounds, including some commonly present in ecosystem-derived samples such as leaf or soil waters.
Leaf waxes protect terrestrial plants from biotic and abiotic stresses and are important sedimentary biomarkers for terrestrial plants. Thus, understanding the production and ablation of leaf waxes is critical in plant physiology and for geochemical studies. However, there have been no accurate approaches to quantify leaf wax production at different time scales.
Carbonate, cellulose, and bulk organic isotope data from varved sediments of Deep Lake (Minnesota) provide a record of paleohydrologic and paleoclimatic change during the deglacial–Holocene transition from 12,000 to 7500 cal BP.
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 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.
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.
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.
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.
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.
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.
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.
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.
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 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.
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).
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.
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.
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.
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.
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.
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.