Rotational Diffusion of Coumarins in Electrolyte Solutions:  The Role of Ion Pairs

1. The influence of solutions of NaCl on the hatching of eggs of Trichostrongylus retortaeformis is studied. It is shown that the effects are not the consequence of colligative properties, but are related to ionic phenomena. 0.05 N-NaCl slows down the rate of hatch without impairing the ultimate ‘hatchability’ of the eggs. Processes of development up to hatching are not slowed down. 2. The effect demonstrated in the case of NaCl is shown to be shared by eight other electrolytes, the depression in the rate of hatch being proportional to the mobility of the ions in solution. On the assumption that the effect of the ions is due to a penetration of the egg membrane(s) the rate of entry is shown to be controlled by the speed of the slower ion in any one salt. 3. The influence of NaCl on the permeability of hatching eggs to water is studied. It is shown that the rate of increase in permeability is slowed down sufficiently in NaCl to control the rate of hatch. The inference that water permeability is a necessary prerequisite for hatching is made, a further hypothetical process being invoked to account for the rate of hatch in the absence of NaCl, since it is not then controlled by changes in water permeability. 4. The probability that the net effect of ionic solutions on the eggs is one concerned with the rate of breakdown of the inner wax-like layer of the egg is strengthened by experiments demonstrating that the depressing influence of NaCl is antagonized by ‘Teepol’, though the comparable influence of other, non-emulsifying, compounds cannot be explained. 5. The role of water permeability in the hatching mechanism is investigated. 6. A hatching mechanism of strongyloid eggs is proposed which involves two processes, the first dependent upon the osmotic relationships of the unhatched larva to its environment, the second being some sort of chemical weakening of the outer shell. 7. It is suggested that the effect of ions on hatching rate assists the ‘embryonated egg’ to survive under natural conditions when the hatched first-stage larva might otherwise be destroyed by desiccation.

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The effect of the trisulfur radical ion on molybdenum transport by hydrothermal fluids

10.5194/egusphere-egu21-3318 ◽

2021 ◽

Author(s):

Maria A. Kokh ◽

Clement Laskar ◽

Gleb S. Pokrovski

Keyword(s):

Composition Range ◽

Ion Pairs ◽

Primary Source ◽

Econ Geol ◽

Hydrothermal Conditions ◽

Earth Planet ◽

Porphyry Deposits ◽

Experimental And Theoretical Studies ◽

Partitioning Behavior

Knowledge of molybdenum (Mo) speciation under hydrothermal conditions is a key for understanding the formation of porphyry deposits which are the primary source of Mo. Existing experimental and theoretical studies have revealed a complex speciation, solubility and partitioning behavior of Mo in fluid-vapor-melt systems, depending on conditions, with the (hydrogen)molybdate (HMoO4-, MoO42-) ions and their ion pairs with alkalis in S and Cl-poor fluids [1-3], mixed oxy-chloride species in strongly acidic saline fluids [4, 5], and (hydrogen)sulfide complexes (especially, MoS42-) in reduced H2S-bearing fluids and vapors [6-8]. However, these available data yet remain discrepant and are unable to account for the observed massive transport of Mo in porphyry-related fluids revealed by fluid inclusion analyses demonstrating 100s ppm of Mo (e.g., [9]). A potential missing ligand for Mo may be the recently discovered trisulfur radical ion (S3&#8226;-), which is predicted to be abundant in sulfate-sulfide rich acidic-to-neutral porphyry-like fluids [10]. We performed exploratory experiments of MoS2 solubility in model sulfate-sulfide-S3&#8226;--bearing aqueous solutions at 300&#176;C and 450 bar. We demonstrate that Mo can be efficiently transported by S3&#8226;--bearing fluids at concentrations ranging from several 10s ppm to 100s ppm, depending on the fluid pH and redox, whereas the available data on OH-Cl-S complexes cited above predict negligibly small (<100 ppb) Mo concentrations at our conditions. Work is in progress to extend the experiments to wider T-P-composition range of porphyry fluids and to quantitatively assess the role of S3&#8226;- in Mo transport by geological fluids.<ul><li>1. Kudrin A.V. (1989) Geochem. Int. 26, 87&#8211;99.</li> <li>2. Minubayeva Z. and Seward T.M. (2010) Geochim. Cosmochim. Acta 74, 4365&#8211;4374.</li> <li>3. Shang L.B. et al. (2020) Econ. Geol. 115, 661&#8211;669.</li> <li>4. Ulrich T. and Mavrogenes J. (2008) Geochim. Cosmochim. Acta 72, 2316-2330.</li> <li>5. Borg S. et al. (2012) Geochim. Cosmochim. Acta 92, 292&#8211;307.</li> <li>6. Zhang L. et al. (2012) Geochim. Cosmochim. Acta 77, 175&#8211;185.</li> <li>7. Kokh M.A. et al. (2016) Geochim. Cosmochim. Acta 187, 311&#8211;333.</li> <li>8. Liu W. et al. (2020) Geochim. Cosmochim. Acta 290, 162&#8211;179.</li> <li>9. Kouzmanov K. and Pokrovski G.S. (2012) Soc. Econ. Geol. Spec. Pub. 16, 573&#8211;618.</li> <li>10. Pokrovski G.S. and Dubessy J. (2015) Earth Planet. Sci. Lett. 411, 298&#8211;309.</li> </ul>

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