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Activated Carbon Engineered Solution to Inactivate Karenia brevis and Adsorb Toxins Associated With Florida Red Tide Domenic Contrino, Leverto Jean Charles, Benjamin Pepper, Alisia Holland, Vince Lovko, and Regina Rodriguez.
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arge ocean blooms of Karenia brevis, often called “Florida red tide” or red tide, have ravaged the Gulf Coast of the United States. When these harmful algal blooms are allowed to grow and migrate toward the coast they cause fish kills, respiratory issues among coastal residents, and billions of dollars in losses to the fishing, tourism, and aquaculture industries of the surrounding areas. Along with human respiratory hazards, elevated toxin levels in the water lead to fish kills, where for miles fish line the shores as they wash up, causing more hazards associated with decomposition and cleanup costs. Algal toxins that leave the water and enter the air cause respiratory irritation and force beaches to shut down and limit people from accessing oceanfront properties, restaurants, and other businesses. As a result, the state of Florida reorganized the Red Tide Task Force in 2019 and approved Florida Senate Bill 1552 establishing the Florida Red Tide Mitigation and Technology Development Initiative, by which this project was funded, to provide funding allocations and expert guidance to address causes and mitigation tools against red tide. Several reports highlight the enormous costs associated with red tide blooms in the Gulf of Mexico to Florida and surrounding states. A 1974 study on a relatively short bloom (four months) estimated the tourism industry of southwest Florida was adversely impacted by an estimated $100 million (based on 2020 dollars) as a result of a fairly mild red tide event four years earlier in 1970 [1, 2]. A report by Hoagland [2] , estimated $4 million in emergency-room charges incurred by health conditions caused by a bloom spanning 2001 and 2002. Financial impacts of a recent 2018 red tide
event, which may have been the largest in recent history, have been recently analyzed by a group at the University of Central Florida [3] to show nonlinear impacts as the bloom persists longer and longer. In late 2017, higher concentrations of red tide began to appear near the coast of southwest Florida. Over the coming months, the bloom grew and spread so far that, by fall 2018, it had rounded the straits of Florida and started to impact the southeast coast of Florida as well. The impacts caused the state to issue a state of emergency for seven counties on the southwestern coast of Florida, where impacts were the most severe and the bloom persisted until spring 2019. Alvarez et al. [3] report that, for southwest, ocean-facing counties of Florida (i.e., Pinellas and Hillsborough counties, down to Monroe), an estimated $1.24 million of revenue was lost per day in areas with a persistent red tide bloom at low concentrations (10,000 to 100,000 cells/L), and up to $1.67 million per day at high bloom concentrations (<1,000,000 cells/L). For the three southeastern oceanfacing counties of Florida with larger tourism destinations (i.e., Miami-Dade, Broward, and Palm Beach) these estimates are $9.79 million per day for low concentrations, and $17.71 million per day for medium concentration (100,000 to 1,000,000 cells/L). In total, this recent red tide event in 2018 is estimated to have impacted these local economies by up to $2.6 billion in losses [3] as tourism and hospitality were severally limited. The current strategy is simply to limit human exposure by avoiding the beach and waiting until the tides, currents, or other natural processes diminish the bloom or shift it away
Table 1. Samples of Powdered Flavonoid and Activated Carbon 1:1 Weight/Weight Blends
Label C1-CA C2-Cr C1-FL C1-IP C1-LU C1-QU
Activated Carbon Carbon 1 Carbon 2 Carbon 1 Carbon 1 Carbon 1 Carbon 1
Algicide Commercial pond algicide Potassium dichromate Flavone Ipriflavone Luteolin Quercetin
72 July 2024 • Florida Water Resources Journal
Domenic Contrino is research engineer, Leverto Jean Charles is research lab technician, Benjamin Pepper is applications engineer, Alisia Holland is research engineer, and Regina Rodriguez is chief executive officer with Carbonxt Inc. in Gainesville. Vince Lovko is staff scientist with Mote Marine Laboratory in Sarasota.
from coastal waters, which in some cases could take months, or even years. A simple approach to this strategy has been proposed, including compilation of existing public data to a single mobile app or webpage [4]. Although effective at limiting human exposure, this avoidance strategy does not address the adverse impacts on marine life or lost revenue, nor does it suggest a solution in limiting bloom spread. The need for a mitigation tool to limit the growth of blooms and actively reduce impacts is apparent. Luteolin and related flavonoid compounds have recently been discussed as a naturally derived candidate for the mitigation of harmful algal blooms. Several studies have looked at the effects of luteolin on various harmful algae, including marine dinoflagellate and freshwater cyanobacteria [5-9]. These studies showed that the compounds reduced cell counts of a control species, rather than the entire phytoplankton community. In one specific instance, as it relates to K. brevis, a marine dinoflagellate (Park et al.) showed the selectivity of their algicide to reducing cell abundance of dinoflagellates, but not diatoms [10] . A possible mechanism of bloom elimination with flavonoids is linked to inhibition of photosynthetic function, here too in a selective manner rather than totally destruction of phytoplankton community [11]. Additional work with quercetin showed no detrimental effect to Chlamydomonas sp. or Dunaliella tertiolecta, but did have strong inhibition of Thalassiosira pseudonana photosynthesis. These reports have been used to assess the methodologies and feasibility of combining an effective algicide with activated carbon in an engineered product for the selective reduction of harmful algae.