question on bacteria...gary?

[Detritivore]

Hi Gary or Jake,

I have a question regarding bacteria and substrate. Is it true that phosphates and other nasties are chemically and biologically bonded to sand by bacteria? hence, the bare-bottom movement? also, do you have any online scientific papers or such regarding the subject?

Thanks!

p.s. forgive my shallow vocabulary when dealing with subjects such as this

[mesocosm]

Greetings All !

... forgive my shallow vocabulary when dealing with subjects such as this

Welcome to the club ... I have a degree in Biological Sciences, and I still have to re-read articles 2 or 3 times to really understand what is being said. Having Google's basic search engine at the ready to utilize it's [define:*****] function also helps.

... I have a question regarding bacteria and substrate. Is it true that phosphates and other nasties are chemically and biologically bonded to sand by bacteria? ...

"Biologically bound" strikes me as a weak phrase ... "bound" to me implies something more than mere attachment/association. "Biologically bound" to me means that it's adhered to a surface ... and can be washed or hydrolysed off that surface rather easily. Having said that ... sequestered ("biologically bound") within a microorganism which in turn is strongly adhered to the surface of a substrate particle? No problem ... I always use the term "sequestered", as opposed to "biologically bound" for reasons of precision ... at least in my warped little mind ... but maybe I'm just nitpicking.

Chemical bonding and crystalization strike me as entirely different from a state of being "biologically bound". Can "nasties" be chemically bound to, or crystalized on the surface of a substrate particle? ... absolutely. But some additional vocabulary is in order ...

Definition of "authigenic":

minerals that form in situ in sediments after deposition.
http://gmbis.marinebiodiversity.ca/B.../glossA-D.html

Formed or generated in place. Said of rocks or minerals formed at the spot where they are now found.
http://imnh.isu.edu/digitalatlas/glossary/letter.asp

There's no question that minerals containing phosphorous can form on the surface of a substrate particle. Typically phosphorous is incorporated into Fe-bound or Ca-bound minerals. Consider ...

From the sediment, pore water samples were collected under anoxic conditions as described by Reeburgh (1967), whereafter dissolved PO4 was determined. In sliced sediment samples (triplicate cores) 4 phosphorous pools were determined by sequential extractions using 1 g of wet sediment: (1) exchangeable PO4, (2) Fe-bound PO4, (3) authigenic Ca-bound PO4, and (4) detrital Ca-bound PO4 (Hieltjes & Lijklema 1980, Ruttenberg 1992, Barbanti et al. 1994).

Extracted from:

Sulfide-induced release of phosphate from sediments of coastal lagoons and the possible relation to the disappearance of Ruppia sp.
S. K. Heijs, R. Azzone, G. Giordani, H. M. Jonkers, D. Nizzoli, P. Viaroli, and H. van Gemerden

Aquatic Microbial Ecology, Volume 23: 85-95, 2000
Full Text Article (pdf)

So ... these sediments contained dissolved PO4 within the pores of the sediment (not chemically bound ... but rather "absorbed"), and exchangeable PO4, Fe-bound PO4, authigenic Ca-bound PO4, and detrital Ca-bound PO4 (chemically bound).

... hence, the bare-bottom movement? also, do you have any online scientific papers or such regarding the subject? ...

The bare-bottom marine aquarium "style" in North America goes back to the early 1980s ... so I'm not sure what "the bare-bottom movement" means ...

...




Here's the Google results using the keywords: bacteria, sand, bound, and phosphate ... LINK.

62,800 hits ... enjoy ...



JMO ... HTH

[Detritivore]

so, rather than actual bonding, the stuff is absorbed into the pores of the sand, implying that it could be released again as well?

by "bare-bottom movement" i mean the recent wave of hobbyists returning the berlin method, with a few modifications such as strong skimming, high flow, etc... the reasoning in ditching a DSB is that it absorbs all the "junk" but after it is "full" the "junk" is leached back into the water resulting in a tank "crash".

[Detritivore]

also gary, here is a thread from the "other site" about scientific journals covering DSB's, marine sedimentation, etc... have you seen it before? if not, i figure this is something you'd appreciate: http://www.reefcentral.com/forums/sh...hreadid=263482

i havent read the whole thread.

[mesocosm]

Greetings All !

... rather than actual bonding, the stuff is absorbed into the pores of the sand, implying that it could be released again as well? ...

There's three things going on: (1) "dissolved in water" PO4 ... the water is absorbed into the matrix of the substrate particle, and moves both in and out of the particle relatively (but not completely) freely; (2) PO4 sequestered within the biomass of bacteria ... typically on the surface of the substrate particle, but not always; and (3) PO4 bound in minerals ... typicaly Ca and Fe based ... that are formed on the surface of the sediment particle.

The dissolved PO4 can't be released, because it was always "free". The PO4 that is sequestered biologically, and the PO4 bound to the surface of the particle, can be ... and eventually will be ... released.


JMO ... HTH