What happens to the shells of invertebrates in the deep water of ocean basins?

Question

Deep water in the ocean basins is cold and has a substantial component of dissolved carbon dioxide gas. What happens to the shells of invertebrates after critters die and the shells settle into this very deep water? a.) silicate shells increase in mass b.) silicate shells dissolve c.) calcite shells increase in mass d.) calcite shells dissolve

Answer 1

The question applies to planktonic shelled organisms living high in the water column, and what becomes of their shells (tests) post-mortem. The shells of these organisms are commonly either calcareous (calcite or aragonite; e.g. foraminifera, pteropoda) or siliceous (silica or opaline silica; e.g. radiolaria). Calcareous shells are subject to dissolution in deep water (which is undersaturated for CaCO3). For calcite, this depth varies in the oceans, but is around 5,000m. This is referred to as the Calcite Compensation Depth (CCD). Aragonite begins to dissolve at shallower depth, around 2,500m (ACD). So calcareous shells are not generally preserved in deep marine sediments. In contrast, silica remains insoluble at depth, so the shells are preserved, and compose a large proportion of deep sea sediment ("siliceous oozes", "radiolarites").

So the answer to the multiple choice is D.

Answer 2

Calcite shells would increase in mass because the CO2 would combine with the calcite to form calcium carbonate....lol even if Im wrong I should get some points for doing your home work lol

Answer 3

First, I never can quite understand why everyone gets bugs in their pants about the "missing heat." The heat is going somewhere. Either out into space or into the oceans. We just have to figure out where and have the tools (and it was the lack of tools which trembath considered to be the tragedy) to verify. Nailing the energy balance is only a secondary corroboration of the general warming trend. It is nice to have to satisfy some of the naysayers and it helps verify climate models. That said using the thermal expansion of water is a reasonable way to deduce the temperature rise in the icy depth. Hard to get enough data points otherwise. So yes, this indicates the depths as the sink for the missing heat, but in of itself, I don't think the paper, based on the abstract, is sufficient. It needs to be corroborated.

Answer 4

Shells are mainly calcium carbonate CaCO3. They will transform into sedimentary rocks (limestone) over the years and so doing extract carbon dioxide CO2 from the atmosphere and enhancing this phenomena could be a part of the solution to the global warming problem.

Answer 5

Most likely you would be below the CCD (Calcite Componsation Depth), so the answer would be D, calcite shells disolve.

Answer 6

How About E. We Don't Know? Or Care?

Answer 7

CORAL REEFS?