hello,

i don't have enough information about henrys law (i have read this law in internet after your question), but i can say that: in deep sea especially in anoxic redox condition, H2S and methane gases concentration are high. Because in this deposition condition S can be enrichment as sulfite form. Henrys law is related with pressure (where the pressure is high, there is more gas concentration in liquid such as sea water). So according to my idea, trace element enrichment could be possible with direct effectively by henrys law.

Henry's law refers to the concentration of a gas dissolved in a liquid and it qould refer to concentrations of trace elements, which occur in a gas phase. This law can be extended to solids for fast diffusing gases like hydrogen, helium, etc.

Please refer:

Lecture Notes - Trace Element

www.science.smith.edu    

Ahmed, Henry's law is one of the ideal solution laws that address the concentration of ideal components in solution (see also Dalton's and Raoult's Laws). The initial experiments and laws were performed with gasses and gas mixtures over water - hence the terms 'ideal gas' and 'ideal solution' laws. Henry's law states that the concentration of an ideal component in a solution is directly proportional to the partial pressure of the element in the gas over the solution (at equilibrium). This relates to trace element behavior - partitioning between solid-solid, or solid-melt, melt-vapor any other combination of phases - due to the infinitely dilute nature of trace elements. Because trace elements are infinitely dilute, theoretically, there are no physical or chemical interactions between trace elements, nor between trace elements and the solvent. Hence the trace element behaves ideally and its concentration in a solution is proportional only to it's concentrations in the surroundings. For trace elements the proportionality constant is the equilibrium distribution coefficient, kd.

The complexity of how we transition these concepts from gas-aqueous equilibria to all other solutions (crystals and vapor), comes from the substitution of Raoult's law into the fundamental equations of thermodynamics. I refer you to the text by Anderson, The Thermodynamics of Natural Systems for an explanation.

I hope this helps.

I fully agree with the previous comment by Michael A. Stewart.

Another way is to refer to the chemical potential of an element and consequently to its activity. The activity is the product of the concentration of the element by its activity coefficient.

This activity coefficient reflects the deviation of the behavior of the element to "ideality". Ideality means that this coefficient is equal to 1 (analogy for gas with the notion of ideality for perfect gas) and consequently the activity of the element is equal to its concentration. One consider that the behavior of an element tends toward ideality (activity coefficient tends toward 1) when its concentration tends towards 0. That is the reason why trace elements are believed to be modelled in a simpler way (through partition coefficients) than major elements.

Your question is not new: it was the object of the first page of the first chapter of my thesis in... 1980 ! if you are interested in modelling trace elements (solid - liquid, melting, crystallization) you may find there some basic developments witch are often by-passed in the current literature, see: http://archimer.ifremer.fr/doc/00034/14512/).

For more elaborate models you may look at: https://www.researchgate.net/publication/260436398_Modelisation_physique_et_chimique_du_comportement_du_manteau_sous_les_dorsales_medio-oceaniques_modele_de_colonne_de_fusion_partielle

Unfortunately, these documents are in french...

Conference Paper Modélisation physique et chimique du comportement du manteau...

Dear Sir

I think the following link will benefit you in your search

https://ocw.mit.edu/courses/earth-atmospheric-and-planetary-sciences/12-479-trace-element-geochemistry-spring-2013/lecture-notes/MIT12_479S13_lec2.pdf

Best Regards

Agree with Michael remark.