toxic substances n.
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  1. TOXIC SUBSTANCES ENSC 202 Stephanie DiBetitto, Josh Fontaine, and Rebecca Zeyzus

  2. LCB’s Proposed Toxic Substance Problems

  3. 3 Subcategories of Toxic Substances • Heavy Metals • Organochlorines: PCBs, dioxin, DDT • Others: VOCs, PAHs, phthalates Substances within these subcategories are posing threats to the LCB

  4. Problem • Many sources (industry, deposition, agriculture, WWTP, etc.) • Many sources contributed from outside LCB • Transported through ecosystems • Synergistic effects • Harmful to many areas of life • Can be persistent within the environment

  5. Objectives • To evaluate negative impacts of the substances of concern • To identify and document the toxic substances’ source, and their modes of transport between habitats and through ecosystems • To examine the risk presented within the habitats and the link between the sources and toxins persisting within the environment

  6. Goal/ Purpose • To understand the potential risk posed by the three subcategories of toxic substances within ecosystems • Apply the findings to a relative risk model for the Lake Champlain Basin in the future

  7. (Methyl- Hg) • NIOSH REL: 0.05 mg/m3

  8. NIOSH REL: 0.050 mg/m3

  9. Figure 2. Surface sample trace metal concentrations (from partial digestion) and TEL, ER-L, PEL, ER-M values. The height of the bar represents the trace metal concentration or guideline value in gg−1. The stations are arranged in roughly a north-south orientation. (Lacey et al., 2001)

  10. Figure 7. Core samples: trace metal concentrations from partial digestion (g g−1) versus depth (cm)below sediment/water interface. The cores are presented in roughly a northwest-southeast transect (Lacey et al., 2001)

  11. General Findings: Organochlorines • Significantly impact the environment and human health at low concentrations • Highly toxic • Highly mobile • Persistent • Hydrophobic • Lipophilic bioaccumulate • Endocrine disruptors

  12. Sources: Organochlorines • *Atmospheric Deposition • Agricultural and Urban Runoff • Waste Water Treatment • Industrial Waste Discharges

  13. Chemical Characteristics:Organochlorines • Semi- volatile • Low vapor pressure • Undergo diffusion, advection, and convection • Co-exist in both gas and particle phases, cycle through the atmosphere and earth’s surface • These processes allow for OCs to be absorbed from the gas phase by water, soil, plant surface and snow and become available within a range of ecosystems and habitats • Arguably most detrimental to natural systems

  14. Forest Ecosystems: Organochlorines • Persist in forests due to deposition • Pollutants in the air are adsorbed to leaf and needle surfaces • Leaf litter transports contaminants to the soil • Different soil horizons undergo alternate responses due to processes like degradation, dissolution, adsorption, and evaporation • Remain in the A-horizon due to its acidic properties in pine forests

  15. Waterways: Organochlorines • Agricultural Runoff • Rivers are the largest receptacles of pesticide waste and agricultural runoff • Enter river systems through surface run-off from urban areas • Bioavailable to the organisms living in the river • Generally found in densely populated areas (target estuaries and coastal marine ecosystems) • Sediments act as a sink for persistent pollutants

  16. Effects of Organochlorines in the Lake Champlain Basin • PCBs and dioxins NIOSH REL: Ca • Found in sediment • Low levels of PCBs throughout the lake- bioaccumulates • Concentration of PCBs exceeds U.S. FDA for fish and EPA guidelines for humans • Largest single source of contaminant from Georgia Pacific sludge bed in Cumberland Bay • Dioxin brought to LCB from pesticide runoff (agriculture) • Both PCBs and dioxin primarily transported from wind currents depositing substances from sources outside of the basin • Fish advisories are a result of the elevated concentrations, promote safe fish consumption and protect human health (Lake Champlain Basin Program, 2011)

  17. NIOSH REL: 1.5 mg/m3

  18. NIOSH REL: 1400 mg/m3

  19. NIOSH REL: Ca

  20. Factors to consider • Input duration • Mass loading • Predator- prey relationships • Sensitivity of species • Flushing time • In mammals may consider gender, age, diet, health condition, reproduction status, and the season determine the effect posed on the mammal • *Risk = product of many factors

  21. Effects Filter Logical link between sources and stressor

  22. Source Impact Filter* Logical link between the effect of the source on the stressor

  23. Habitat Impacts Filter* Stressors logical link to the habitat

  24. Uncertainty • Input frequency and intensity unquantified • Effect on aquatic organisms dependent on exposure severity and the physiochemical properties of the parent compound and the products it is transformed into • Synergisms between chemicals within environment and amongst each other

  25. Conclusions • An abundance of toxins entering the Lake from outside the basin via deposition • Primary sources of toxins include industrial and agricultural runoff and WWTP • Bioaccumulative and persistent properties of these substances increase risk

  26. Recommendations • Education, Advisories • Disposal • Monitor sediments, find trends in changes over time • Revolution

  27. THE END WARNING: This is what happens when toxins get into the Lake (featured above, Champ taking a dip in the LCB)