As the human population of Florida and the World increases so does its effects on the natural environment. This talk centers on man’s addition of huge amounts of the primary plant nutrients nitrogen and phosphorus into the surface waters of southern Florida. This is termed ‘cultural eutrophication’ meaning that man’s activities (anthropogenic) over fertilize our natural waters (Lakes, streams, rivers, estuaries and oceans).

Most recently, the “algal”, actually cyanobacterial, bloom in Lake Okeechobee during June-July 2016 and its spread to the St. Lucie canal and Estuary, Indian River Lagoon, Caloosahatchee River and Estuary and the Palm Beach Canal and Lake Worth Lagoon grabbed national attention. The bloom forming cyanobacterium in this case was Microcystis aeruginosa and unfortunately it was also a toxic form. The toxin it produces is a neurotoxin and can be bio-amplified by aquatic organisms becoming a health hazard to man. In addition, just the contaminated water can cause skin rashes and respiratory problems.

Other blooms do indeed occur in southern Florida including, but not limited to, the Red Tide in the Gulf of Mexico on Florida’s west coast and the Brown Tide in the Indian River Lagoon.

We will explore the increasing nutrient problem (pollution) of our waters and cover some suggested paths to potentially and hopefully reverse these trends.

The Indian River Lagoon (IRL) has experienced problems associated with increasing macroalgal blooms, seagrass epiphytization, and hypoxia/anoxia for decades. Following significant rainfall in Spring 2011 that ended a multi-year drought, a severe “super bloom” of phytoplankton (> 100 µg/L Chl a) developed in the northern IRL. This was followed by a “brown tide” in the northern IRL and Mosquito Lagoon in 2012, which was followed by widespread seagrass die-off and wildlife mortality, including endangered manatees. To better understand the nutrient source(s) and dynamics surrounding these harmful algal blooms (HABs), seawater samples and benthic macroalgae were collected at a network of 20 stations throughout the IRL. High TDN concentrations (up to 152 µM) and TDN:TDP ratios (>100:1) in the poorly flushed northern IRL, Mosquito Lagoon and Banana River segments reflected the accumulation and cycling of N-rich groundwater and surface water inputs that produce P- limitation. Macroalgae del 15N values were enriched throughout the IRL (+6.3 o/oo) and similar to values reported for macroalgae from other sewage-polluted coastal waters. Because point-source sewage inputs to the IRL were largely eliminated through the IRL Act of 1990, these results suggest that non-point source N enrichment from septic tanks (300,000-600,000) represents a significant and largely ignored N-source to the IRL. The high degree of sewage N contamination of the IRL, combined with recent HABs, including toxic ecotypes of the red macroalga Gracilaria tikvahiae McLachlan, seagrass loss, and wildlife mortality, indicates a critical need for improved sewage collection and treatment, including nutrient removal.

Massive algal blooms have occurred in the St. Lucie Estuary, FL during the summers of 2016, 2013 and 2005. The release of nutrient laden waters from Lake Okeechobee reduced salinity in the Estuary. High nutrients, low salinity and warm, sunny days made the St. Lucie Estuary the perfect medium for the uncontrolled proliferation of Microcystis aeruginosa already present in the Lake waters. Microcystis aeruginosa can produce microcystins; a family of heptapeptides associated with acute hepatoxicity in humans and animals. During the 2016 bloom, the Florida Department of Environmental Protection detected Microcystin-LR equivalents up to 414 µg/L as compared to the safe drinking water limit of 20 µg/L for recreational use established by the World Health Organization. However, this study aimed to analyze the toxin distribution of the 2016 bloom and compared it to a previous bloom in 2005. UPLC/MS/MS analysis allowed for identification of variants present, classifying MC-LR as the most abundant variant followed by MC-LA with concentrations of 4500 and 815 µg/L respectively. Accurate characterization of the toxic profile of these blooms allow for the correct assessment of health hazard measures as well as future targeting and removal of toxins from water.

Protection of our natural waters from pollution is critical to maintaining clean drinking water supplies and healthy habitats for aquatic organisms. Assessment of the sources of contamination to waterbodies is important for developing effective mitigation strategies. Chemical and microbial indicators can be used to determine exposure of natural waters to human and animal contamination. Recalcitrant chemical compounds, such as sucralose (an artificial sweetener) and pharmaceuticals, have been suggested as indicators for wastewater contamination of natural waters. Pathogenic bacteria released from the fecal material of humans and animals cause illness and pose major health hazards when present in drinking water. Fecal bacteria enter natural waters through urban runoff that carries human and animal waste, leaky septic systems, and runoff from agricultural and farm systems. Distinguishing the source of fecal bacteria is important for developing strategies for mitigation of these contaminants. This presentation will examine a microbial source tracking study using genetic biomarkers specific to the fecal material of human, dog, bird, and cow found in Central Florida and to use that method to analyze environmental waters within Orange County. Additionally, the waters will be analyzed for sucralose and pharmaceuticals as supplemental indicators of human wastewater contamination.

The chemical speciation of phosphorus (P) in freshwater lakes controls the bioavailability of P to aquatic organisms including algae, and ultimately affects the occurrence of large algal blooms. In lakes with high sedimentation rates, P may become quickly buried and subsequently deplete the availability of reactive P within the water column. The objective of this study was to determine the speciation of P in a central Florida lake water column and sediment in order to understand the seasonal controls that affect P bioavailability. Water and sediment samples were collected in May, July, and November 2016 representing spring, summer, and fall, respectively. The primary forms of P speciation include soluble (bioavailable), adsorbed to particulates, precipitated in minerals, and incorporated within organics. Sediments in Lake Silver included shallow, sandy/silty fractions containing a high percentage of adsorbed P and deeper, muddy fractions containing a higher organic P fraction. Preliminary analyses indicate that the adsorption of P to particle surfaces is the primary controlling factor affecting P bioavailability in Lake Silver sediments, particularly during the summer months when plant and algae productivity is highest.

Food, pharmaceutical, environmental and biological samples contain high volume of matrix interferents that may interfere with the sample preparation techniques used and require sample pretreatment processes such as filtration, centrifugation, protein precipitation etc., prior to analyte extraction. These extra steps are laborious, time consuming, and may result in significant analyte loss and poor data quality.

Fabric sorptive extraction (FPSE) has been developed to handle samples containing high volume of interferents without any sample pretreatment. The FPSE device utilizes a piece of fabric as the substrate to chemically bind polymeric sorbent (such as polydimethylsiloxane) via sol-gel reaction. The sol-gel sorbent provides unique selectivity towards the target analyte, porous sorbent allows rapid mass transfer of the analyte from the bulk sample for analyte-sorbent interaction and the fabric substrate acts as a bait via hydrophilic/hydrophobic interactions to lure the target analyte(s). As a result, FPSE provides a near exhaustive extraction in a relatively short period.

After the extraction, the device is exposed to a small volume of organic solvent for analyte back-extraction. The analyte solution is then centrifuged to remove particulate materials.

Several recent applications of FPSE for extracting important pharmaceuticals and personal care product residues from environmental water will be presented.

Recently, the decontamination of organophosphate flame retardants from aqueous solution has received a considerable interest due of their potential threat to human health and the environment.  We report herein the TiO₂ photocatalytic oxidation of the flame retardant, tris-(2-chloroethyl) phosphate (TCEP), from aqueous solution. GC-NPD was used to monitor the disappearance of TCEP concentration during photocatalytic degradation. Our results demonstrate more than 90% of TCEP ([TCEP] <100 µM) is degraded within 1 hour upon irradiation at 350 nm in oxygen-saturated aqueous suspension of TiO₂ at ambient temperature.  The degradation follows pseudo first order kinetics with rate constants varying from 0.28 to 0.03 min^-1 depending on the initial concentrations over the range of 18– 270 µM. The rate constant for the degradation decreases with increasing initial TCEP concentration, implying the process may be controlled by mass transfer (adsorptiondesorption) at the surface of TiO₂. This kinetic behavior is also consistent with the Langmuir-Hinshelwood model implying oxidation occurs at the surface of TiO₂. The solution pH does not have a major impact on the degradation from pH 4-9. Mineralization to chloride and phosphate were monitored by IC over 5 hours of extended irradiation and an excellent mass balance was observed for both anions. The degradation decreases by ~ 50% with the addition of an equal amount of the hydroxyl radical scavenger, coumarin, indicating hydroxyl radicals are the main species participating in the degradation mechanism. The diester adducts of TCEP are the primary intermediates identified by NMR.  These results suggest that photocatalytic oxidation will be useful for the decontamination of aqueous solutions contaminated with recalcitrant organophosphate compounds.