EXAMINING THE VALIDITY OF THE AQUATIC/TERRIGENOUS RATIO AS A PRECURSOR TO HARMFUL ALGAL BLOOMS

Short-chain n-alkanes (n-pentadecane, n-heptadecane, and n-nonadecane) stem primarily from algal matter. Long-chain n-alkanes (n-heptacosane, n-nonacosane, and n-hentriacontane) originate from terrigenous/land plants and are introduced to coastal waters by runoff. Since alkanes are hydrophobic compounds, they tend to concentrate in the microlayer, which serves as the interface between the water and atmosphere. This study strives to provide an expanded understanding of the aquatic/terrigenous ratio (ATR) as a parameter to further assist current methods of predicting and identifying the presence of HABs.

Corpus Christi Bay microlayer samples have been collected by immersing a clean glass plate vertically into the water to collect a sample of the microlayer. To determine the efficacy of this parameter and the extraction process, samples from multiple sites were extracted via liquid-liquid extraction (LLE) and analyzed using Gas Chromatography-Mass Spectrometry (GC-MS). Alkane detection is adequate at very low concentrations, and the extraction method of alkanes along with the detection limits of the GC-MS are currently being evaluated to investigate suitable conditions for ATR determination.