Multi-Hazard Mitigation Plan: 08. Lava And Vog

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Chapter 8:Hazard Analysis—Lava and VOG have suggested that the plume may be providing an overabundance of nuclei that have inhibited drop growth resulting in a decline in rainfall rates in Ka'u and South Kona. The sulfur dioxide as well as the dry deposition of the plume aerosols can cause a variety of adverse impacts on the downwind environment and communities: 1) Sulfur dioxide and residual acid aerosols (that haven't reacted with ammonia) have been found to have broad detrimental impacts on non-native and agricultural crop biota. (There is some evidence that native plants have developed a degree of resistance to sulfur dioxide and/or the acid constituents in the plume.) The farming communities in Ka'u and HOVE have seen extensive defoliation and leaf damage to both edible crops as well as flowering and ornamental plants (tomatoes, lettuce, roses, protea, etc.). 2) The acid aerosols have been found to substantially lower the pH of rainfall. In locations with limited rainfall (e.g. HOVE) the combined effect of dry deposition of acid aerosols onto roofs, along with acid rainfall, substantially lowers the pH (becoming more acid) of domestic rainwater catchment systems. The likely consequences of the acidified domestic water are increased corrosion of the metallic constituents of both the roof and the plumbing equipment, as well as potential adverse health impacts from consuming the water (e.g. weakened dental enamel, poor uptake of dietary minerals). Increased acidity of the rainfall also has the potential to increase heavy metal exposure from leaching lead from paint (manufactured prior to 1978 when lead oxide was banned from paint) or plumbing systems that have used tin-lead alloys in their solder. The acid will likewise increase corrosion to any exposed metal along the path of the downwind plume including fencing, water lines, water tanks, farm equipment, etc. Even in relatively dry downwind areas, severe corrosion will generate significant economic losses. The most likely process driving the corrosion is dew formation rather than the infrequent rainfall: during the evening hours, as the dew point temperature is approached, the hygroscopic acid aerosols will form an extremely corrosive film, with pH as low as 1, on metallic surfaces. With daily replenishment of fresh acid from dry deposition, and nightly condensation of moisture it's reasonable to anticipate substantially more rapid deterioration of exposed metal surfaces than would occur in similar environments not exposed to the plume acids. A further effect of the increased loading of acid onto agricultural lands in the downwind areas will be accelerated leaching of minerals from the soil column. To date, this process has not been fully researched and, hence, it's difficult to offer an assessment of the long-term impacts of acidification of rainfall on the agriculture communities downwind of Kilauea. 3) The dry deposition of the acid aerosols and ammonia salts will increase the exposure of the downwind environment and communities to chloride, sulfate, and fluoride ions. Whereas moderate dietary intake of chloride and sulfate ion are relatively benign, fluoride ion is both an essential element, at low rates of intake, but can be extremely 8-6 Hawaii County Multi-Hazard Mitigation Plan