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The Sett­ling of Po­rous Par­ti­cles in Wa­ter

The Max Planck So­cie­ty sup­ports a sci­en­ti­fic col­la­bo­ra­ti­on bet­ween the Max Planck In­sti­tu­te for Ma­ri­ne Mi­cro­bio­lo­gy and the Mas­sa­chus­sets In­sti­tu­te of Tech­no­lo­gy, MIT.
 
The Max Planck So­cie­ty (MPS) sup­ports a sci­en­ti­fic col­la­bo­ra­ti­on bet­ween the Bio­geo­che­mis­try De­part­ment of the Max Planck In­sti­tu­te for Ma­ri­ne Mi­cro­bio­lo­gy in Bre­men and the Ci­vil En­gi­nee­ring De­part­ment of Mas­sa­chu­setts In­sti­tu­te of Tech­no­lo­gy (MIT), on stu­dy­ing the `Settling behavior of porous particles in stratified oceans'. The aim of the pro­ject is the pre­dic­tion of the sett­ling times of po­rous par­ti­cles and thus their role in car­bon ex­port and thin lay­er for­ma­ti­on. The Ma­the­ma­ti­cal Mo­de­ling Group of the MPI will per­form the mo­de­ling part, whe­re­as the ex­pe­ri­men­tal stu­dies will be car­ri­ed out joint­ly with MIT.
The eco­lo­gy and bio­geo­che­mis­try of the oce­an are stron­gly in­flu­en­ced by par­ti­cle sett­ling, as par­ti­cles are the main vec­tor of car­bon ex­port from the up­per oce­an towards the oce­an floor. The lat­ter me­cha­nics re­pres­ents a key com­po­nent of the oce­an car­bon cy­cle

Most ma­ri­ne par­ti­cles are high­ly po­rous re­sul­ting in pe­cu­li­ar flu­id dy­na­mi­cal be­ha­vi­or that in­flu­en­ces the sett­ling pro­cess con­sider­ab­ly, in par­ti­cu­lar at den­si­ty in­ter­faces (py­cno­cli­nes). At py­cno­cli­nes, it is found that the par­ti­cle sett­ling speed is dra­ma­ti­cal­ly re­du­ced. This re­sults in en­han­ced op­por­tu­nities for ma­ri­ne mi­cro­or­ga­nisms to at­tach to par­ti­cles, as well as in the ac­cu­mu­la­ti­on of par­ti­cles and the for­ma­ti­on of thin lay­ers. The­se lay­ers are ubi­qui­tous in the oce­an, and are be­lie­ved to play a si­gni­fi­cant eco­lo­gi­cal role, hos­ting lo­ca­li­zed eco­sys­tems whe­re ab­un­dance and growth of or­ga­nisms are en­han­ced.

"De­s­pi­te the im­port­an­ce of the­se re­gi­ons, we are still in the dark as to the un­der­ly­ing flu­id me­cha­nics of their for­ma­ti­on, for which the sett­ling dy­na­mics of in­di­vi­du­al par­ti­cles is a fun­da­men­tal com­po­nent", says Prof. Kha­li­li from MPI. In the col­la­bo­ra­ti­on pro­ject bet­ween the Ma­the­ma­ti­cal Mo­de­ling Group and MIT, they are go­ing to stu­dy ma­the­ma­ti­cal­ly and ex­pe­ri­men­tal­ly the sett­ling be­ha­vi­or of ag­gre­ga­tes in a den­si­ty-stra­ti­fied am­bi­ent.

The pro­ject is sup­por­ted by the Max Planck So­cie­ty (MPS) for 3 ye­ars.




Addendum:
At pre­sent, the­re is an opening for a post­doc stu­dent
to work par­ti­al­ly at MIT and par­ti­al­ly at MPI-Bre­men.

High­ly qua­li­fied ex­pe­ri­men­tal phy­si­cists or me­cha­ni­cal en­gi­neers with ex­cel­lent ex­pe­ri­ence in non-in­va­si­ve vi­sua­liza­t­i­on me­thods (PIV, PTV, PLIF) are in­vi­ted to con­tact
Prof. Arz­hang Kha­li­li. akhalili@mpi-bremen.de
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