Does metabolic water control the phosphate oxygen isotopes of microbial cells?

The oxygen isotopes ratio (δO) of microbial cell water strongly controls the δO of cell phosphate and of other oxygen-carrying moieties. Recently it was suggested that the isotopic ratio in cell water is controlled by metabolic water, which is the water produced by cellular respiration. This potentially has important implications for paleoclimate reconstruction, and for measuring microbial carbon use efficiency with the O-water method.

Archaeomagnetism in the Levant and Mesopotamia Reveals the Largest Changes in the Geomagnetic Field.

Our understanding of geomagnetic field intensity prior to the era of direct instrumental measurements relies on paleointensity analysis of rocks and archaeological materials that serve as magnetic recorders. Only in rare cases are absolute paleointensity data sets continuous over millennial timescales, in sub-centennial resolution, and directly dated using radiocarbon. As a result, fundamental properties of the geomagnetic field, such as its maximum intensity and rate of change have remained a subject of lively discussion.

Seasonal variation and mobility of trace metals in the beach sediments of NW Borneo.

Miri city has a dynamic coastal environment, mainly influenced by intensive sedimentation from the Baram River and excessive trace metal loading by the Miri River, which are significant environmental concerns. As the mobility, bioavailability, and toxicity of the trace metals in the sediments are largely controlled by their particulate speciation, the modified BCR sequential extraction protocol was applied to determine the particulate speciation of trace metals in the coastal sediments of Miri, to unravel the seasonal geochemical processes responsible for known observations, and to identify possible sources of these trace metals. The granulometric analysis results showed that littoral currents aided by the monsoonal winds have influenced the grain size distribution of the sediments, enabling us to divide the study area into north-east and south-west segments where the geochemical composition are distinct.

Tropospheric carbonyl sulfide mass balance based on direct measurements of sulfur isotopes.

Robust estimates for the rates and trends in terrestrial gross primary production (GPP; plant CO uptake) are needed. Carbonyl sulfide (COS) is the major long-lived sulfur-bearing gas in the atmosphere and a promising proxy for GPP. Large uncertainties in estimating the relative magnitude of the COS sources and sinks limit this approach.

Effects of Light Pollution on the Early Life Stages of the Most Abundant Northern Red Sea Coral.

The growth in human population along coastal areas is exposing marine environments to increasing anthropogenic light sources. Despite the potential effects of this modern phenomenon, very few studies have examined its implications for corals. Here, we present a long-term study of coral early life stages under light pollution conditions at night.

The geologic history of seawater oxygen isotopes from marine iron oxides.

The oxygen isotope composition (δO) of marine sedimentary rocks has increased by 10 to 15 per mil since Archean time. Interpretation of this trend is hindered by the dual control of temperature and fluid δO on the rocks' isotopic composition. A new δO record in marine iron oxides covering the past ~2000 million years shows a similar secular rise.

Photoacclimation and induction of light-enhanced calcification in the mesophotic coral .

Corals and their photosymbionts experience inherent changes in light along depth gradients, leading them to have evolved several well-investigated photoacclimation strategies. As coral calcification is influenced by light (a process described as LEC-'light-enhanced calcification'), studies have sought to determine the link between photosynthesis and calcification, but many puzzling aspects still persist. Here, we examine the physiology of , a coral species found at a wide range of depths but that is strictly mesophotic in the Red Sea; and also examines the coupling between photosynthesis and LEC by investigating the response of the coral under several controlled light regimes during a long-term experiment.

Sulfur isotopes ratio of atmospheric carbonyl sulfide constrains its sources.

Carbonyl sulfide (COS) is the major long-lived sulfur bearing gas in the atmosphere, and is used to estimate the rates of regional and global (both past and current) photosynthesis. Sulfur isotope measurements (S/S ratio, δS) of COS may offer a way for improved determinations of atmospheric COS sources. However, measuring the COS δS at the atmospheric concentrations of ~0.

Use of C- and phosphate O-labeled substrate for studying phosphorus and carbon cycling in soils: a proof of concept.

Rationale: Stable isotope tracers are commonly used to track the transformations of organic carbon (C) and nitrogen (N) in soils but they have not been used to follow coupled cycles of phosphorus (P) and C because P has only one stable isotope.

Methods: A novel dually labeled substrate, composed of a C-labeled glucose backbone attached to a phosphate group with known δ O value, was used to follow the fate of C and P derived from the same compound. The substrate was amended to soils from two natural oak forests, differing in their P levels, and the δ C values of respired CO and the δ O values of soil bioavailable P were measured.

Six centuries of geomagnetic intensity variations recorded by royal Judean stamped jar handles.

Earth's magnetic field, one of the most enigmatic physical phenomena of the planet, is constantly changing on various time scales, from decades to millennia and longer. The reconstruction of geomagnetic field behavior in periods predating direct observations with modern instrumentation is based on geological and archaeological materials and has the twin challenges of () the accuracy of ancient paleomagnetic estimates and () the dating of the archaeological material. Here we address the latter by using a set of storage jar handles (fired clay) stamped by royal seals as part of the ancient administrative system in Judah (Jerusalem and its vicinity).

Measuring the ratio of CO2 efflux to O2 influx in tree stem respiration.

In recent studies, the ratio of tree stem CO efflux to O influx has been defined as the apparent respiratory quotient (ARQ). The metabolism of carbohydrates, the putative respiratory substrate in trees, is expected to yield an ARQ of 1.0.

Substantial dust loss of bioavailable phosphorus from agricultural soils.

Phosphorus (P) is an essential element in terrestrial ecosystems. Knowledge on the role of dust in the biogeochemical cycling of phosphorus is very limited with no quantitative information on aeolian (by wind) P fluxes from soils. The aim of this study is to focus on P cycling via dust emissions under common land-use practices in an arid environment by integration of sample analyses and aeolian experiments.

Tracing the Sources of Atmospheric Phosphorus Deposition to a Tropical Rain Forest in Panama Using Stable Oxygen Isotopes.

Atmospheric dust deposition can be a significant source of phosphorus (P) in some tropical forests, so information on the origins and solubility of atmospheric P is needed to understand and predict patterns of forest productivity under future climate scenarios. We characterized atmospheric dust P across a seasonal cycle in a tropical lowland rain forest on Barro Colorado Nature Monument (BCNM), Republic of Panama. We traced P sources by combining remote sensing imagery with the first measurements of stable oxygen isotopes in soluble inorganic phosphate (δ(18)OP) in dust.

Instability of thermoremanence and the problem of estimating the ancient geomagnetic field strength from non-single-domain recorders.

Data on the past intensity of Earth's magnetic field (paleointensity) are essential for understanding Earth's deep interior, climatic modeling, and geochronology applications, among other items. Here we demonstrate the possibility that much of available paleointensity data could be biased by instability of thermoremanent magnetization (TRM) associated with non-single-domain (SD) particles. Paleointensity data are derived from experiments in which an ancient TRM, acquired in an unknown field, is replaced by a laboratory-controlled TRM.

Corals concentrate dissolved inorganic carbon to facilitate calcification.

The sources of dissolved inorganic carbon (DIC) used to produce scleractinian coral skeletons are not understood. Yet this knowledge is essential for understanding coral biomineralization and assessing the potential impacts of ocean acidification on coral reefs. Here we use skeletal boron geochemistry to reconstruct the DIC chemistry of the fluid used for coral calcification.

A sensitive method for the sulfur isotope analysis of dimethyl sulfide and dimethylsulfoniopropionate in seawater.

Rationale: Dimethyl sulfide (DMS) is the major volatile sulfur species emitted to the atmosphere from the oceans. The sulfur isotope ratio ((34)S/(32)S) of DMS may offer a way to calculate the contribution of marine DMS to global sulfur cycling. The S-isotopic analysis of DMS is difficult due to its low concentrations in natural seawater and high chemical reactivity.

Soil phosphate stable oxygen isotopes across rainfall and bedrock gradients.

The stable oxygen isotope compositions of soil phosphate (δ(18)O(p)) were suggested recently to be a tracer of phosphorus cycling in soils and plants. Here we present a survey of bioavailable (resin-extractable or resin-P) inorganic phosphate δ(18)O(p) across natural and experimental rainfall gradients, and across soil formed on sedimentary and igneous bedrock. In addition, we analyzed the soil HCl-extractable inorganic δ(18)O(p), which mainly represents calcium-bound inorganic phosphate.

Determining the relationship between tree-stem respiration and CO2 efflux by δO2/Ar measurements.

Respiration in forest tree stems is an important component of the global carbon cycle. This respiration is traditionally estimated by measurements of the CO(2) efflux from the stem. However, recent studies have suggested that movement of CO(2) in the transpiration stream causes large errors in the respiration estimated by the CO(2) efflux.

A method for analyzing the δ18O of resin-extractable soil inorganic phosphate.

Improved tools for tracing phosphate transformations in soils are much needed, and can lead to a better understanding of the terrestrial phosphorus cycle. The oxygen stable isotopes in soil phosphate are still not exploited in this regard. Here we present a method for measuring the oxygen stable isotopes in a fraction of the soil phosphate which is rapidly available to plants, the resin-extractable P.

Mercury depletion events in the troposphere in mid-latitudes at the Dead Sea, Israel.

The occurrence of mercury depletion events (MDE) in the Polar Regions during the spring periods has raised global concern due to the biomagnifications of the deposited mercury into the aquatic food chain. However, it now appears that MDE is not limited to the Polar Regions and can also occur at mid-latitudes. Diurnal cycles of mercury, ozone, and BrO behavior based on short-time resolution measurements are presented for the Dead Sea, Israel, for Summer 2006.

Diffusivity fractionations of H2(16)O/H2(17)O and H2(16)O/H2(18)O in air and their implications for isotope hydrology.

We have determined the isotope effects of (17)O and (18)O substitution of (16)O in H(2)O on molecular diffusivities of water vapor in air by the use of evaporation experiments. The derived diffusion fractionation coefficients (17)alpha(diff) and (18)alpha(diff) are 1.0146 +/- 0.

High-precision measurements of 17O/16O and 18O/16O of O2 and O2/Ar ratio in air.

A method for high-precision and high-accuracy mass spectrometric measurements of the ratios among the three oxygen isotopes, and of the O(2)/Ar ratio, is presented. It involves separation of the O(2)-Ar mixture from air and includes a fully automated system that ensures highly reliable sample processing. Repeated measurements of atmospheric oxygen yield the repeatability (+/-SE x t, standard error of the mean (n = 12) multiplied by Student's t-factor for a 95% confidence limit) of 0.

Assessment of oceanic productivity with the triple-isotope composition of dissolved oxygen.

Plant production in the sea is a primary mechanism of global oxygen formation and carbon fixation. For this reason, and also because the ocean is a major sink for fossil fuel carbon dioxide, much attention has been given to estimating marine primary production. Here, we describe an approach for estimating production of photosynthetic oxygen, based on the isotopic composition of dissolved oxygen of seawater.