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,…

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 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…

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 (…

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…

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…

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…

Statistical study of analyses of water from 43 samples from geothermal wells, three groundwater wells, and one sample of local rainwater along with rainwater data from the Global Network of Isotopes in Precipitation has been used to identify the origin and evolution of geothermal water in the Niutuozhen (牛驼镇) geothermal field and estimate the renewability rate of its geothermal resource.…

Sixteen groundwater samples collected from production wells tapping Lower Cretaceous Nubian Sandstone and fractured basement aquifers in Sinai were analyzed for their stable isotopic compositions, dissolved noble gas concentrations (recharge temperatures), tritium activities, and ¹⁴C abundances. Results define two groups of samples: Group I has older ages, lower recharge…

A stratigraphy-based chronology for the North Greenland Eemian Ice Drilling (NEEM) ice core has been derived by transferring the annual layer counted Greenland Ice Core Chronology 2005 (GICC05) and its model extension (GICC05modelext) from the NGRIP core to the NEEM core using 787 match points of mainly volcanic origin identified in the electrical conductivity measurement (ECM) and…

The Gunt River catchment in the Central Pamirs is a representative of the headwater catchments of the Aral Sea Basin. It covers 14,000 km², spanning altitudes between 2000 and 6700 m a.s.l. In a monitoring network, water samples were taken at 30 sampling points every month and analysed for the stable water isotopes (¹⁸O and ²H). Our first results…

This paper presents the initial results of a scientific drilling project to recover core and pressurized fluid samples from a natural CO₂ reservoir, near the town of Green River, Utah. The drilling targeted a stacked sequence of CO₂-charged Jurassic sandstone reservoirs and caprocks, situated adjacent to a CO₂-degassing normal fault. This site has actively…

The identification and quantification of methane emissions from natural gas production has become increasingly important owing to the increase in the natural gas component of the energy sector. An instrumented aircraft platform was used to identify large sources of methane and quantify emission rates in southwestern PA in June 2012. A large regional flux, 2.0–14 g CH₄ s^−1…

Atmospheric concentration measurements are used to adjust the daily to monthly budget of CO₂ emissions from the AirParif inventory of the Paris agglomeration. We use 5 atmospheric monitoring sites including one at the top of the Eiffel tower. The atmospheric inversion is based on a Bayesian approach, and relies on an atmospheric transport model with a spatial resolution of 2…

Weekly samples from surface waters, springs, soil water and rainfall were collected in a 76.9 km2 mountain rain forest catchment and its tributaries in southern Ecuador. Time series of the stable water isotopes δ18O and δ2H were used to calculate mean transit times (MTTs) and the transit time distribution functions (TTDs) solving the convolution…

We present CH₄ concentration [CH₄] and the partial pressure of CO₂ (pCO₂) in bulk sea ice from subarctic, land-fast sea ice in the Kapisillit fjord, Greenland. The bulk ice [CH₄] ranged from 1.8 to 12.1 nmol L⁻¹, which corresponds to a partial pressure range of 3 to 28 ppmv. This is markedly higher than the…

The addition of pyrogenic carbon (C) in the soil is considered a potential strategy to achieve direct C sequestration and potential reduction of non-CO₂ greenhouse gas emissions. In this paper, we investigated the long term effects of charcoal addition on C sequestration and soil physico-chemical properties by studying a series of abandoned charcoal hearths in…

Extra-tropical cyclones, such as 2012 Superstorm Sandy, pose a significant climatic threat to the northeastern United Sates, yet prediction of hydrologic and thermodynamic processes within such systems is complicated by their interaction with mid-latitude water patterns as they move poleward. Fortunately, the evolution of these systems is also recorded in the stable isotope ratios of storm-…

Accumulation is a key parameter governing the mass balance of the Greenland ice sheet. Several studies have documented the spatial variability of accumulation over wide spatial scales, primarily using point data, remote sensing or modeling. Direct measurements of spatially extensive, detailed profiles of accumulation in Greenland, however, are rare. We used 400 MHz ground-penetrating radar…

The groundwater flow systems and chemistry in the deep part of the coastal area of Japan have attracted attention over recent decades due to government projects such as geological disposal of radioactive waste. However, the continuous groundwater flow system moving from the shallow to deep parts of the sedimentary soft rock has not yet been characterized. Therefore, the Cl^–, δD…

The destructive effects of sulfate attack on concrete structures are well known, but the reaction paths and mechanisms that cause the deterioration are still under debate. The aim of this study is to contribute to a deeper understanding on investigating concrete damage by introducing a novel and promising multi proxy approach method. The methodology comprises advanced…

RATIONALE:

Low-budget rain collectors for water isotope analysis, such as the 'ball-in-funnel type collector' (BiFC), are widely used in studies on stable water isotopes of rain. To date, however, an experimental quality assessment of such devices in relation to climatic factors does not exist.

METHODS:

We used Cavity Ring-Down…

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-…

Development of cavity ring-down spectroscopy (CRDS) has enabled real-time monitoring of carbon stable isotope ratios of carbon dioxide and methane in air. Here we demonstrate that CRDS can be adapted to assess aquatic carbon cycling processes from microbial to ecosystem scales. We first measured in situ isotopologue concentrations of dissolved CO₂ (¹²CO_2…

Changes in atmospheric circulation over the past five decades have enhanced the wind-driven inflow of warm ocean water onto the Antarctic continental shelf, where it melts ice shelves from below. Atmospheric circulation changes have also caused rapid warming…

Scarcity of mercury species records in the Southern Hemisphere is a critical weak point for the development of appropriate modeling and regulation scenarios. Under the framework of the “Global Mercury Observation System” (GMOS) project, a monitoring station has been set up on Amsterdam Island (37_480 S, 77_340 5 E) in the remote southern Indian Ocean. For the first time in the Southern…

Background and aims

Positive relationships between temperature and soil respiration rate are widely observed, but it remains unclear if the relationships are due to increases in soil organic matter mineralisation (R _om), or in root and rhizosphere respiration (R _roots), or increases in both. This study aims to determine the relative…

Chemical and stable isotopic compositions (δD, δ¹⁸O, and δ³⁴S) of non-volcanic hot spring waters around the Miocene Kofu granitic complex surrounding the Kofu basin in the South Fossa Magna region of central Honshu, Japan, were analyzed in order to investigate water–rock interactions and to determine the origin and sulfur isotopic characteristics of their trace amounts…

A new method of extracting regional background concentration of CO₂ in Yangtze River Delta was established based on the observations of both black carbon concentration and meteorological parameters. The concentrations of CO₂ and black carbon were observed at Lin'an regional background station from 2009 to 2011. The regional background concentration of CO_…

Radiocarbon can be used to trace fossil fuel CO₂ (CO₂ff) in the atmosphere, because radiocarbon has been depleted in fossil fuels. Here we present our study on the spatial distribution and temporal variations of CO₂ff in Xi'an City, China using Δ¹⁴C of both green foxtail (Setaria viridis, L. Beauv.) leaf samples and…

Assessing the impacts of methane released from hydrate-bearing environments on global carbon cycling would require detailed insights into the distributions and capacities of microbial communities at different horizons of sediment column. In this study, we conducted geochemical, gene abundance and diversity analyses for a sediment core retrieved from a potential hydrate-bearing region off…

The Siberian region is still sparsely covered by ecosystem observatories, which motivates the exploitation of existing data sets to gain spatially and temporally better-resolved carbon budgets. The Zotino Tall Tower Observatory (ZOTTO; 60°48' N, 89°21' E) observations of CO₂ and CH₄ mole fractions as well as meteorological parameters from six different…

Atmospheric carbon dioxide (CO₂) mole fractions were continuously measured from January 2009 to December 2011 at four atmospheric observatories in China using cavity ring-down spectroscopy instruments. The stations are Lin'an (LAN), Longfengshan (LFS), Shangdianzi (SDZ), and Waliguan (WLG), which are regional (LAN, LFS, SDZ) or global (WLG) measurement stations of the World…

Measurements of the ¹⁷O_excess of H₂O were obtained from ice cores in West and East Antarctica. Combined with previously-published results from East Antarctica, the new data provide the most complete spatial and temporal view of Antarctic ¹⁷O_excess to date. There is a steep spatial gradient of ¹⁷O_excess in present-…

Facilitation and competition between different vegetation layers may have a large impact on small-scale vegetation development. We propose that this should not only influence overall herbaceous layer yield but also species distribution and understory longevity, and hence the ecosystems carbon uptake capacity especially during spring. We analyzed the effects of trees on…

We report trends in springtime ozone (O₃) and carbon monoxide (CO) at the Mt. Bachelor Observatory (MBO) in central Oregon, U.S.A. from 2004 to 2013. Over the 10-year period the median and 95th percentile springtime O₃ increased by 0.76 ± 0.61 ppbv yr⁻¹ (1.7 ± 1.4% yr⁻¹) and 0.87 ± 0.73 ppbv…

Biogeochemical dynamics under seasonal ice cover were investigated in the shallow (<10 m) water column of highly productive Georgetown Lake, western Montana, USA. This high altitude (1,800 m) reservoir is well-mixed in summer, but becomes strongly stratified under ice cover (mid-November–mid-May). A rapid drop in dissolved oxygen (DO) concentration and rise in dissolved…

Stable isotopes in water (δ²H and δ¹⁸O) are important indicators of hydrological and ecological pattern and process. δ²H and δ¹⁸O of water are incorporated into geological and biological systems in a predictable manner and have been used extensively as tracers in hydrological, ecological and forensic studies. Physical processes result in spatial…

An instrumented sample holder was developed for time-lapse micro-tomography of snow samples to enable in-situ nondestructive spatial and temporal measurements under controlled advective airflows, temperature gradients, and air humidities. The design was aided by computational fluid dynamics simulations to evaluate the airflow uniformity across the snow sample. Morphological and mass…

In the Ziz Basin, located in arid area in southeastern Morocco, surface waters are scarce and local populations are entirely dependent on groundwater resources for drinking and irrigation. In order to evaluate the main factors controlling the origin and salinization of groundwater resources, we have investigated the chemical and stable isotope compositions of groundwater and surface water…

The chemical and physical properties of secondary organic aerosol (SOA) formed by the photochemical degradation of biogenic and anthropogenic volatile organic compounds (VOC) are as yet still poorly constrained. The evolution of the complex refractive index (RI) of SOA, formed from purely biogenic VOC and mixtures of biogenic and anthropogenic VOC, was studied over a diurnal cycle in the…

• The oxygen isotope signature of water is a powerful tracer of water movement from plants to the global scale. However, little is known about the short-term variability of oxygen isotopes leaving the ecosystem via transpiration, as high-frequency measurements are lacking.
• A laser spectrometer was coupled to a gas-exchange chamber directly estimating branch-level fluxes in order…

In order to better understand the constraints on the use of barium as a coastal paleo-freshwater tracer, we surveyed the dissolved Ba distribution in Louisiana Shelf waters, including the Mississippi (MR) and Atchafalaya (AR) River plumes, during May and November 2008, and June/July 2009, which represent high, low and intermediate river discharges, respectively. Dissolved Ba was found…

In atmospheric and environmental sciences, optical spectrometers are used for the measurements of greenhouse gas mole fractions and the isotopic composition of water vapor or greenhouse gases. The large sample cell volumes (tens of milliliters to several liters) in commercially available spectrometers constrain the usefulness of such instruments for applications that are limited in sample…

In this paper, we report the vertical profiles of CO₂ and CH₄ measured with a cavity ring-down spectrometer (CRDS) on a research aircraft from near-ground level to 8 km above mean sea level. The airborne platform employed in this paper is an Alpha Jet aircraft operated from NASA's Ames Research Center. Flights were undertaken to Railroad Valley, NV, USA, to…

Hillslopes are the dominant landscape components where incoming precipitation is transferred to become groundwater, streamflow or atmospheric water vapor. However, directly observing flux partitioning in the soil is almost impossible. Hydrological hills-lope models are therefore being used to investigate the involved processes. Here we report on a modeling experiment using the Catchment…

Precise methods for the detection of geologically stored CO₂ within and above soil surfaces are an important component of the development of carbon capture and storage (CCS) under terrestrial environments. Although CO₂ leaks are not expected in well-chosen and operated storage sites, monitoring is required by legislation and any leakage needs to be quantified…

A Particle-into-Liquid Sampler – Total Organic Carbon and fraction collector sys-tem was flown aboard a Twin Otter aircraft sampling prescribed burning emis-sions in South Carolina in November 2011 to obtain smoke marker measure-ments. The fraction collector provided 2min time-integrated off-line samples for car-bohydrate (i.e., smoke markers levoglucosan, mannosan, galactosan) analysis by…

Rapid Arctic warming is associated with important water cycle changes: sea ice loss, increasing atmospheric humidity, permafrost thaw, and water-induced ecosystem changes. Understanding these complex modern processes is critical to interpreting past hydrologic changes preserved in paleoclimate records and predicting future Arctic changes. Cyclones are a prevalent Arctic feature and…

Anthropogenic modification of the water cycle involves a diversity of processes, many of which have been studied intensively using models and observations. Effective tools for measuring the contribution and fate of combustion-derived water vapor in the atmosphere are lacking, however, and this flux has received relatively little attention. We provide theoretical estimates and a first…