Domoic acid excretion in dungeness crabs, razor clams and mussels     

Schultz IR  Skillman A  Woodruff D 《Marine environmental research》2008,66(1):21-23

Domoic acid (DA) is a neurotoxic amino acid produced by several marine algal species of the Pseudo-nitzschia (PN) genus. We studied the elimination of DA from hemolymph after intravascular (IV) injection in razor clams (Siliqua patula), mussels (Mytilus edulis) and Dungeness crabs (Cancer magister). Crabs were also injected with two other organic acids, dichloroacetic acid (DCAA) and kainic acid (KA). For IV dosing, hemolymph was repetitively sampled and DA concentrations measured by HPLC-UV. Toxicokinetic analysis of DA in crabs suggested most of the injected dose remained within hemolymph compartment with little extravascular distribution. This observation is in sharp contrast to results obtained from clams and mussels which exhibited similarly large apparent volumes of distribution despite large differences in overall clearance. These findings suggest fundamentally different storage and elimination processes are occurring for DA between bivalves and crabs.  相似文献   

Thermodynamic stability studies of the basic copper carbonate mineral,malachite     

James L Symes  Dana R Kester 《Geochimica et cosmochimica acta》1984,48(11):2219-2229

Natural malachite is a well defined solid demonstrating reproducible solubility behavior over a wide range of pH. The following equilibrium constants associated with the malachite dissolution equilibrium at 25°C, 1 atm were determined: (infinite dilution) (0.72 ionic strength) (36.9‰ salinity seawater). The temperature dependence of a “mixed” equilibrium constant, K_sp⁺, of the form: has been measured at I = 0.72, yielding the relationship: within a 5–25°C temperature range. The effect of pressure on the solubility of malachite in water and seawater was estimated from partial molar volume and compressibility data. For 25 °C at infinite dilution $\text{K'}{}_{\mathrm{sp}}\text{(1000 bar)}\text{K'}{}_{\mathrm{sp}}\text{(0)}\text{= 240}$ and in seawater $\text{K′}{}_{\mathrm{sp}}\text{(1000)}\text{K'}{}_{\mathrm{sp}}\text{(0)}\text{= 44}$.Comparison of stoichiometric and apparent malachite equilibrium constants has been used to estimate the extent of copper(II) ion interaction at the ionic strength of seawater. In dilute carbonate medium (total alkalinity, TA = 2.4 meq/kg H₂O, pH 8.3), 2.9% of total dissolved copper exists as the free copper(II) ion and in seawater (S = 36.9%., TA = 2.3 meq/kg H₂O, pH = 8.1), $\text{[Cu}{}^{\mathrm{2+}}\text{]}\text{T(Cu)}$ is 3.1%.Total dissolved copper levels of approximately 450–750 nMol/Kg are necessary to attain malachite saturation conditions in the open ocean. Observations of malachite particles suspended in seawater must be explained by precipitation or solid phase substitution reactions from localized environments rather than by direct precipitation from bulk seawater.  相似文献   

The relation between the magnitude derived from surface and from body waves for station průhonice     

Dana Knaislová  Reviewer A. Zátopek 《Studia Geophysica et Geodaetica》1982,26(4):400-405

auam aum¶rt;, m u n¶rt; n a¶rt;u u nm a anu, umua a u mauu u 1964–1976 . ¶rt; aum¶rt; ma auau aum¶rt;, n¶rt; uu m .  相似文献   

Vulnerability of groundwater in Quaternary aquifers to organic contaminants: a case study in Wuhan City,China   总被引：5，自引：0，他引：5  

Yanxin Wang  Broder J. Merkel  Yilian Li  Hui Ye  Surong Fu  Dana Ihm 《Environmental Geology》2007,53(3):479-484

More than 30 organic contaminants were detected in shallow groundwaters at Wuhan, the largest city in central China. Seriously contaminated groundwaters were from densely populated, industrial and commercial areas. Abnormal concentrations were found in groundwater from Hankou, downtown Wuhan: trimethylbenzene up to 29 μg/L, tetramethylbenzene up to 866 μg/L, and trichloroethene up to 9.5 μg/L. Benzene, Toluene, Ethylene and Xylene (BTEX) contamination of groundwater is serious and widespread at Wuhan, ranging between 0.14 and 25.0 μg/L. Considering the hydrogeological conditions of most Chinese cities, DRAMIC, a modified version of the widely used DRASTIC model, was proposed by the authors for assessing vulnerability of groundwater to contamination. The factors D, R, A and I in DRAMIC model are the same as in DRASTIC. The factor topography is ignored. The factor soil media is substituted by a new factor aquifer thickness (M) and the factor hydraulic conductivity of the aquifer by a new factor impact of contaminant (C). The equation for determining the DRAMIC Index is: DRAMIC = 5D _R + 3R _R + 4A _R + 2M _R + 5I _R + 1C _R. The calculated DRAMIC Index can be used to identify areas that are more likely to be susceptible to groundwater contamination relative to each other. The higher the DRAMIC Index is, the greater the groundwater pollution potential. Applying DRAMIC, a GIS-based vulnerability map for Wuhan city was prepared. Interestingly, places such as downtown Hankou, where enhanced concentrations of BTEX have been detected, correspond quite well with those with higher DRAMIC ratings.  相似文献   

A computational method for approximating a Darcy–Stokes system governing a vuggy porous medium     

Todd Arbogast  Dana S. Brunson 《Computational Geosciences》2007,11(3):207-218

We develop and analyze a mixed finite element method for the solution of an elliptic system modeling a porous medium with large cavities, called vugs. It consists of a second-order elliptic (i.e., Darcy) equation on part of the domain coupled to a Stokes equation on the rest of the domain, and a slip boundary condition (due to Beavers–Joseph–Saffman) on the interface between them. The tangential velocity is not continuous on the interface. We consider a 2-D vuggy porous medium with many small cavities throughout its extent, so the interface is not isolated. We use a certain conforming Stokes element on rectangles, slightly modified near the interface to account for the tangential discontinuity. This gives a mixed finite element method for the entire Darcy–Stokes system with a regular sparsity pattern that is easy to implement, independent of the vug geometry, as long as it aligns with the grid. We prove optimal global first-order L ² convergence of the velocity and pressure, as well as the velocity gradient in the Stokes domain. Numerical results verify these rates of convergence and even suggest somewhat better convergence in certain situations. Finally, we present a lower dimensional space that uses Raviart–Thomas elements in the Darcy domain and uses our new modified elements near the interface in transition to the Stokes elements.  相似文献   

Relation between microseisms recorded at seismic stations Praha and Průhonice     

Dana Procházková  Reviewer A. Zátopek 《Studia Geophysica et Geodaetica》1978,22(4):362-367

Summary In order to compare the course of microseisms recorded at the seismic stations of Praha and Prhonice, the relation between Praha (Wiechert astatic inverted pendulum) and Prhonice (Kirnos — electromagnetic seismographs) amplitudes was derived, using data from the time interval September 1967 — June 1968. It was found that the amplitudes at both stations are almost parallel in time with three almost simultaneous local maxima. In addition corresponding relations have also been found to be valid for the periods.  相似文献   

Isoseismals of the strongest Friuli aftershocks of September 1976     

Vít Kárník  Dana Procházková  Zdeňka Schenková  Julius Drimmel  Dieter Mayer-Rosa  Dragutin Cvijanovic  Vladimir Kuk  Andelka Miloševič  Francesco Giorgetti  Reviewer J. Janský 《Studia Geophysica et Geodaetica》1978,22(4):411-414

Summary Isoseismal maps of the three strongest Friuli aftershocks of September 1976 were compiled using the contributions from European countries within the shaken area. The characteristic features of the macroseismic fields are discussed.  相似文献   

Macroseismic observations of earthquake in Yugoslavia (April 15, 1979, 06h21m gmt), on the territory of Czechoslovakia     

Dana Procházková  Vít Kárník  Ivan Brouček  Reviewer A. Zátopek 《Studia Geophysica et Geodaetica》1980,24(1):102-103

an¶rt;u am mu 15- an 1979. a auu a mumuu auu.  相似文献   

Numerical solution of micro-physical equations in a model of a convective cloud     

Dana Lakomá  Reviewer O. Zikmunda 《Studia Geophysica et Geodaetica》1977,21(1):85-98

Summary The procedure for computation and the numerical results of the first testing of the so-called Mi-operation, which is a construction unit of the model of a convective cloud[1] and represents the formulation of microphysical phenomena occurring in a convective cloud, are described. In this paper the Mi-operation is applied to the case of the liquid stage, restricted to condensation and drop evaporation. The solution of the corresponding system of kinetic equations serves the purpose of an initial test of the applicability of the integration method to the type of equations mentioned.  相似文献   

The shape of a two-dimensional embryo on the basal face of ice in dependence on supersaturation     

Dana Lakomá  Reviewer O. Zikmunda 《Studia Geophysica et Geodaetica》1974,18(3):310-312

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