Aquatic invasive species vector management: challenges and practical solutions on the eve of new global shipping regulations
Date of Award
Great Lakes Institute for Environmental Research
IMO D-2, Sampling effort, THMs, vector control
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A new world standard for ballast water management (IMO-D2) will be enforced commencing September 2017. This thesis aims to achieve required final population abundances for target organisms. In chapter 2, I tested synergy effects with two ballast water treatments (chlorination and ballast water exchange). Chapter 3 evaluated the number and volume of samples required to achieve defined error rates. Chapter 4 estimated potential production and exposure to disinfection by-products that may occur when chlorine-treating ballast water. Shipboard trials were carried out en route from Canada to Brazil with sampling carried out using a multiport ballast-tank sampling installation designed for these experiments, followed by statistical modeling and simulation for accuracy determination. Bench experiments for by-product formation were carried out with water samples collected from the same origin ports and a ballast tank to mimic water salinity and natural organic matter content. By-products were analyzed over time to determine potential exposure of vessel personnel. Combined treatment performed equal or better than each treatment alone. Synergistic effects were found for Escherichia coli resulting in greatest reductions when treatments were combined. Antagonistic effects (i.e. less than additive) were detected for phytoplankton and coliform bacteria, possibly due to replenishment of individuals after ballast water exchange. Synergistic effects could not be assessed for zooplankton due to complete elimination of viable individuals in all chlorine treatments. Multiport sampling reduced variability from within-tank aggregation. As volume and replicate number increased, error rates decreased. The best tradeoff for accuracy, precision and practicality was obtained using 1m3 ballast samples. Concerns for potential exposure to chemical treatment by-products for vessel personnel were justified, as single-pulse dosing can lead to significant production of harmful trihalomethane by-products, particularly in brackish ballast water with greater natural organic content, but also for marine and freshwater ballast supplemented with organic content. Freshwater chemical by-product levels were lowest for all treatments examined. Meeting performance-based ballast water effluent standards starting in 2017 will be challenging. My thesis demonstrates that sample sizes for effluent compliance testing should be substantial (1 m3), and that combinations of treatments may offer the greatest opportunities for reducing target organism abundances to values below permissible thresholds.
Hernández Castañeda, Marco Raúl, "Aquatic invasive species vector management: challenges and practical solutions on the eve of new global shipping regulations" (2017). Electronic Theses and Dissertations. 5984.