Processo de acressão mineral

[Luis Rosa]

Boas andei a passear por ai e reparei nestas experiências

 

One of the experiments currently conducted in the Coral Reef Exhibit is the Electro Mineral Accretion (EMA) experiment. This effective method of growing corals with electricity is currently used in worldwide research and holds high potential for restoring coral reefs damaged by ship groundings, blast fishing and related causes of reef destruction. Reef HQ Interns are project managing the Electro Mineral Accretion Experiment.

 

What is EMA?

 

In the late seventies, scientists discovered that when an electric current through steel mesh in seawater, the mesh would soon be covered by a thick layer of limestone. Limestone is a composition of several different minerals, including calcium carbonate, the mineral that corals use to grow. The electric current attracts those minerals, takes them out of solution and deposits them on the electrified surface.

 

It works according to the principles of a battery. The system is composed of one positive pole, called a cathode and one negative pole, the anode. When an electric current is sent through this system, some of the dissolved minerals in the seawater will be attracted to the positive pole, while others will be attracted to the negative pole. Various chemical reactions will take place at both poles. On the anode, bubbles of oxygen and chlorine gas will form. These bubbles will float to the surface and dissolve into the air. On the cathode, bubbles of hydrogen gas and a precipitate of limestone will be produced. This limestone layer can grow very thick, depending on how long the system is connected to electricity. This process of precipitating minerals from seawater onto a surface by the use of electricity is called electro mineral accretion.

 

 

EMA and corals

 

When corals grow in the wild, they extract minerals from seawater and use them to build into their limestone skeleton. After the discovery of electro mineral accretion, other scientists came up with the idea of attaching pieces of coral to the mesh (the cathode). They reasoned that if they put the corals on that surface, the calcium carbonate needed for the growth of their limestone skeleton would be attracted to the cathode and be much easier for the coral to obtain. The theoretical result would be that corals that are stimulated by an electric current grow faster than corals without stimulation. Evidence even exists that corals that are grown by the EMA method are less susceptible to stress and disease. These observations could prove important in future reef restoration activities.

 

:D The experiment in the Coral Reef Exhibit

 

At Reef HQ, we are currently experimenting with the possibilities of this method. Four PVC frames were fitted with snake mesh. This mesh will serve as the cathode. Two coral colonies were fragmented into little pieces and these were fixed to the mesh. Two of the frames were fitted with magnesium anodes underneath and connected to a 12-volt car battery. The other two frames have no current passing through them and serve as controls. This will allow Reef HQ scientists to compare the results later and see if and how much the powered corals have grown in comparison to the non-powered corals.

 

Possibilities for the future of Reef HQ

 

If this experiment shows us that we can actually make corals grow faster, we might be able to use this to grow our own corals for the Coral Reef Exhibit. Besides that, we could even artificially create our own coral reef by shaping mesh into any desired form and put power on it. On the limestone base, coral larvae and other animals can settle and turn it into a reef.

 

If you look closely, the first results are showing already; on the mesh of the far two frames, a white layer of limestone is visible. You might also notice gas bubbles ascending to the surface. These are the oxygen and chlorine bubbles from the anodes under the mesh. The frames closest to the window are the two non-powered controls.

 

Podem ver mais aqui: http://www.reefhq.com.au/bts/electro.html

 

Penso que devem ter relatorios sobre fragmentação de corais.

 

Cumps

[Diogo Lopes]

Olá,

 

Este é um processo sobre o qul ouve um documentário, salvo erro no Discovery muito interessante - há uns meses largos recordo-me de ter sido discutida a hipótese de ser aplicado à aquariofilia, mas na altura a conclusão foi que os nossos sistemas seriam pequenos demais para a sua aplicação!

 

Abraço,

Diogo