The depth is between 10 to 40 meters, these were powdered cement in bags, corals approximately within a 1800 sq.m. area were damaged as the cargo boat beached and listed to spill its load, almost 2000 bags were thrown into the area. Some bags burst open some were intact left lying in the seas. Non government institutions are working hard to mitigate the damage, local government are finding ways to punish the culprit and institute legislative action to prevent future occurrences. Data on the how to proceed is scarce (powdered cements effects), hence this posting.
Well Reverend you may not be correct in your answer. Cement is acidic. I collected this from a site. This is not the tell all to end all, but gives us a glimpse in the right direction. reef tanks are a more sensitive, and therefore need to be kept at the higher end of the pH scale, 8.0 to 8.4. This is a quote about salt water tanks. They have to simulate the conditions in the wild to get the corral to grow in a tank. The 8.0 to 8.4 is slightly alkaline. The cement dropping the ph any could have an impact.
Cement or concrete in and of itself are not harmful to the environment. Governments and private companies are using such items to help rebuild lost reefs. It what may be added to the cement that is a problem.
