Everyone wants their boat to look just like new even after it has spent years out on the water. But, as every boat owner knows, the corrosion of metal pieces is inevitable and replacing parts can get very costly. We were approached by an industry partner who was experiencing complaints from boaters on the west coast of Florida who claimed their chrome boat parts were corroding during the Karenia brevis blooms (Florida Red Tide) of 2017 - 2019. This resulted in costly repairs that were covered under warranty ($10,000 per boat!). The industry partner speculated that red tide toxins (e.g. brevetoxin) were somehow causing the corrosion. We hypothesized instead that the culprit was sulfide fluxing from sediments from the decay of organic material (the decaying red tide but also any dead fish, etc.). Sulfide is known to corrode chrome and other metallic parts in permanently sulfidic areas such as the Black Sea. This was consistent with the largest ever documented anoxic zone at that same time that stretched from the Caloosahatchee River Estuary to over 6 km offshore and covered 100 km2!
We are now performing experiments to determined which alternative metallic plating or coating processes are best suited to protect their metal parts in a wide range of environments: oxic, anoxic, and sulfidic artificial seawater, and in the future, water with algal toxins present. We monitor the oxygen and sulfide levels using electrochemical sensors. Over the course of a few days to weeks, we have noticed some really interesting corrosion patterns - the sulfide causes massive corrosion in just hours! This project will give our partner (and the wider boating industry greater understanding of the problem at hand, and the ability to offer their customers the best parts available.
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