Modeling the marine aragonite cycle: changes under rising carbon dioxide and its role in shallow water CaCO3 dissolution

The marine aragonite cycle has been included in the global biogeochemical model PISCES to study the role of aragonite in shallow water CaCO3 dissolution. Aragonite production is parameterized as a function of mesozooplankton biomass and aragonite saturation state of ambient waters. Observation-based estimates of marine carbonate production and dissolution are well reproduced by the model and about 60% of the combined CaCO3 water column dissolution from aragonite and calcite is simulated above 2000 m. In contrast, a calcite-only version yields a much smaller fraction. This suggests that the aragonite cycle should be included in models for a realistic representation of CaCO3 dissolution and alkalinity. For the SRES A2 CO2 scenario, production rates of aragonite are projected to notably decrease after 2050. By the end of this century, global aragonite production is reduced by 29% and total CaCO3 production by 19% relative to pre-industrial. Geographically, the effect from increasing atmospheric CO2, and the subsequent reduction in saturation state, is largest in the subpolar and polar areas where the modeled aragonite production is projected to decrease by 65% until 2100.

Oxygen Isotopic and Soluble Ionic Composition of a Shallow Firn Core, Inilchek Glacier, Central Tien Shan

Oxygen isotopic and soluble ionic measurements made on snow-pit (2 in depth) and firn-core (12.4 m depth samples recovered from the accumulation zone 5100 m) of Inilchek glacier 43degrees N, 79degrees E) provide information on recent (1992-98) climatic and environmental conditions in the central Tien Shan region of central Asia. The combined 14.4 m snow-pit/firn-core profile lies within the firn zone, arid contains only one observed melt feature (10 m temperature = - 12 degreesC), Although some post-depositional attenuation of the sub-seasonal delta(18)O record is possible, annual cycles are apparent throughout the isotope profile. We therefore use the preserved delta(18)O record to establish a depth/age scale for the core. Mean delta(18)O values for the entire core and for summer periods are consistent with delta(18)O/temperature observations, and suggest the delta(18)O record provides a means to reconstruct past changes in summer surface temperature at the site. Major-ion (Na(+), K(+), Mg(2+), Ca(2+), NH(4)(+), Cl(-), NO(3)(-), SO(4)(2-)) data from the core demonstrate the dominant influence of dust deposition on the soluble chemistry at the site, arid indicate significant interannual variability in atmospheric-dust loading during the 1900s. Anthropogenic impacts oil NH(4)(+) concentrations are observed at the site, and suggest a summer increase in atmospheric NH(4)(+) that may be related to regional agricultural (nitrogen-rich fertilizer use activities.

ANALYTICAL MODELS OF EXOPLANETARY ATMOSPHERES. I. ATMOSPHERIC DYNAMICS VIA THE SHALLOW WATER SYSTEM

Within the context of exoplanetary atmospheres, we present a comprehensive linear analysis of forced, damped, magnetized shallow water systems, exploring the effects of dimensionality, geometry (Cartesian, pseudo-spherical, and spherical), rotation, magnetic tension, and hydrodynamic and magnetic sources of friction. Across a broad range of conditions, we find that the key governing equation for atmospheres and quantum harmonic oscillators are identical, even when forcing (stellar irradiation), sources of friction (molecular viscosity, Rayleigh drag, and magnetic drag), and magnetic tension are included. The global atmospheric structure is largely controlled by a single key parameter that involves the Rossby and Prandtl numbers. This near-universality breaks down when either molecular viscosity or magnetic drag acts non-uniformly across latitude or a poloidal magnetic field is present, suggesting that these effects will introduce qualitative changes to the familiar chevron-shaped feature witnessed in simulations of atmospheric circulation. We also find that hydrodynamic and magnetic sources of friction have dissimilar phase signatures and affect the flow in fundamentally different ways, implying that using Rayleigh drag to mimic magnetic drag is inaccurate. We exhaustively lay down the theoretical formalism (dispersion relations, governing equations, and time-dependent wave solutions) for a broad suite of models. In all situations, we derive the steady state of an atmosphere, which is relevant to interpreting infrared phase and eclipse maps of exoplanetary atmospheres. We elucidate a pinching effect that confines the atmospheric structure to be near the equator. Our suite of analytical models may be used to develop decisively physical intuition and as a reference point for three-dimensional magnetohydrodynamic simulations of atmospheric circulation.

Balanced bilinguals favor lexical processing in their opaque language and conversion system in their shallow language

Referred to as orthographic depth, the degree of consistency of grapheme/phoneme correspondences varies across languages from high in shallow orthographies to low in deep orthographies. The present study investigates the impact of orthographic depth on reading route by analyzing evoked potentials to words in a deep (French) and shallow (German) language presented to highly proficient bilinguals. ERP analyses to German and French words revealed significant topographic modulations 240-280ms post-stimulus onset, indicative of distinct brain networks engaged in reading over this time window. Source estimations revealed that these effects stemmed from modulations of left insular, inferior frontal and dorsolateral regions (German>French) previously associated to phonological processing. Our results show that reading in a shallow language was associated to a stronger engagement of phonological pathways than reading in a deep language. Thus, the lexical pathways favored in word reading are reinforced by phonological networks more strongly in the shallow than deep orthography.

Shallow Dialogue Processing Using Machine Learning Algorithms (or not)

This paper presents a shallow dialogue analysis model, aimed at human-human dialogues in the context of staff or business meetings. Four components of the model are defined, and several machine learning techniques are used to extract features from dialogue transcripts: maximum entropy classifiers for dialogue acts, latent semantic analysis for topic segmentation, or decision tree classifiers for discourse markers. A rule-based approach is proposed for solving cross-modal references to meeting documents. The methods are trained and evaluated thanks to a common data set and annotation format. The integration of the components into an automated shallow dialogue parser opens the way to multimodal meeting processing and retrieval applications.

Fate and effects of drilling wastes in a shallow estuarine mesocosm

To address concerns expressed about the possible effect of drilling mud discharges on shallow, low-energy estuarine ecosystems, a 12 month study was designed to detect alterations in water quality and sediment geochemistry. Each drilling mud used in the study and sediments from the study site were analyzed in the laboratory for chemical and physical characteristics. Potential water quality impacts were simulated by the EPA-COE elutriation test procedure. Mud toxicity was measured by acute and chronic bioassays with Mysidopsis bahia, Mercenaria mercenaria, and Nereis virens.^ For the field study, a relatively pristine, shallow (1.2 m) estuary (Christmas Bay, TX) without any drilling activity for the last 30 years was chosen for the study site. After a three month baseline study, three stations were selected. Station 1 was an external control. At each treatment station (2, 3), mesocosms were constructed to enclose a 3.5 m$\sp3$ water column. Each treatment station included an internal control site also. Each in situ mesocosm, except the controls, was successively dosed at a mesocosm-specific dose (1:100; 1:1,000; or 1:10,000 v/v) with 4 field collected drilling muds (spud, nondispersed, lightly-treated, and heavily-treated lignosulfonate) in sequential order over 1.5 months. Twenty-four hours after each dose, water exchange was allowed until the next treatment. Station 3 was destroyed by a winter storm. After the last treatment, the enclosures were removed and the remaining sites monitored for 6 months. One additional site was similarly dosed (1:100 v/v) with clean dredged sediment from Christmas Bay for comparison between dredged sediments and drilling muds.^ Results of the analysis of the water samples and field measurements showed that water quality was impacted during the discharges, primarily at the highest dose (1:100 v/v), but that elevated levels of C, Cr (T,F), Cr$\sp{+3}$ (T, F), N, Pb, and Zn returned to ambient levels before the end of the 24 hour exposure period or immediately after water exchange was allowed (Al, Ba(T), Chlorophyll ABC, SS, %T). Barium, from the barite, was used as a geochemical tracer in the sediments to confirm estimated doses by mass balance calculations. Barium reached a maximum of 166x background levels at the high dose mesocosm. Barium levels returned to ambient or only slightly elevated levels at the end of the 6 month monitoring period due to sediment deposition, resuspension, and bioturbation. QA/QC results using blind samples consisting of lab standards and spiked samples for both water and sediment matrices were within acceptable coefficients of variation.^ In order to avoid impacts on water quality and sediment geochemistry in a shallow estuarine ecosystem, this study concluded that a minimal dilution of 1:1,000 (v/v) would be required in addition to existing regulatory constraints. ^