A baseline assessment of environmental conditions and the potential for polycyclic aromatic hydrocarbons (PAHs) biodegradation in marina waters and sediments

A baseline assessment of the environmental impacts of a “typical marina” compared to general development impacts in nearshore areas of the northeast Caribbean was conducted. Contaminants associated with marinas (polycyclic aromatic hydrocarbons (PAHs) and heavy metals) were measured using gas chromatography-ion trap mass spectrometry (GC-ITMS) and inductively coupled plasma MS (ICP-MS), respectively. Polychlorinated biphenyls (PCBs) and pesticides were analyzed using GC with electron capture detection (GC-ECD). Biodegradation of PAHs was assessed using a modified pour plate technique and BIOLOG plates to evaluate the ability of indigenous bacteria to utilize PAHs as a sole carbon source for growth. Within marina PAH concentrations averaged 943ng/L (water) and 384ng/g (sediments). Non-marina PAH concentrations averaged 1173ng/L and 126ng/g in water and sediments, respectively. PCB concentrations averaged 137ng/L (water) and 20.4ng/g (sediments) within marinas, and 396ng/L (water) and 1.40nglg (sediment) outside. Pesticide levels within marinas averaged 33.8ng/L (water), and 2.91 ng/g in sediments, and 5.10ng/L (water) and 1.01 ng/g (sediment) outside. The average total sediment heavy metal concentration within marinas was 987μg/g, and 188 μg/g outside. The relative environmental quality of marinas, compared to non-marina areas subject to similar non-marina contaminant inputs, is not significantly different, but does differ in the types of predominant contamination. Both internal/marina and external/developed sites are degraded compared to the control station in a relatively undeveloped sub-watershed. Bacteria capable of degrading some portion of various PAHs were isolated. The results indicate that organisms capable of utilizing PAHs as a carbon source are present, and that some biodegradation occurs in these areas. Thirty three percent of the bacteria isolated from the control station were capable of utilizing PAHs as a carbon source, suggesting that this capability is present in about one-third of the general population of bacteria in this region. Based on these results, it is concluded that sediment characteristics, surrounding land-use, and past property uses are the most useful siting and design considerations for new marina development. These factors are also important in selecting the most appropriate and effective BMPs (best management practices) to minimize marina environmental impacts.