Determination of mercury in Magicicada.

摘要

The purpose of this doctoral research project is to broaden the scientific basis for understanding the impact of gaseous mercury emissions from stationary point sources and mobile sources on terrestrial life forms. Particulate mercury emissions were not considered. The underlying hypothesis is that mercury emissions contribute significantly to the measured bioaccumulation in Periodical Cicadas.; Existing literature on mercury contamination focuses on birds, mammals, aquatic life forms and water-based transport mechanisms. This study examines the presence of mercury in terrestrial insects, specifically the seventeen-year Periodical Cicada. An analysis of insects (Magicicada septendecium, Magicicada cassinii, and Magicicada septendecula) from Brood I in Eagles Nest, VA and from and Brood X in Cincinnati, OH reveals the presence of mercury in the adult cicada in concentrations ranging from 0.01 to 4.46 ppmw. This level is comparable to mercury concentrations in herbivorous fish. Male cicadas contained a higher concentration than female cicadas in all species studied.; Although Periodical Cicadas live underground for seventeen years, an analysis of mercury in soils was inconclusive. The variation in the soil samples reflected the heterogeneous nature of soils. The concentration of mercury in soils ranged from zero to more than twenty-five times the average concentration measured in the cicadas collected at a given location.; A dispersion model of mobile source emissions using ISC ST3 indicated a very weak correlation between the mercury measured in adult cicadas and the volume of traffic on nearby roads. The percentage of Class B & C vehicles (for example, eighteen-wheelers) in traffic volumes on interstate I-75 on the section north of the Lockland split and south of interstate I-275 contributed significantly to the predicted deposition on the ground and concentration in the air in Evendale, Ohio.; A slightly stronger relationship existed between mercury in cicadas and predicted mercury deposition and concentration from utilities, primarily coal-fired boilers and sludge combustors in the Cincinnati area; however, the relationship between bioaccumulation and location was not straightforward. The dispersion model predicted plume depletion at Ronald Regan Cross County Highway, a distance of approximately 25 km from the large power plants along the Ohio River. The model predicted an above average concentration of mercury in the air along highway corridors extending north along Interstate I 75 to the Sharon Road exit and east and west of I 75 along Ronald Regan Cross County Highway for several miles. Emissions from non-utility businesses in the Mill Creek Valley affected collection sites in Elmwood Place due to mercury deposition and in Winton Terrace due to the concentration of mercury in the air. Sludge incinerators contributed to the predicted above average deposition on Mt. Adams.; This study is the first to consider the contamination of adult, terrestrial insects due to gaseous mercury emissions from mobile and stationary sources. Included are emissions from non-utility businesses; electric utilities and sludge combustors in Dearborn County, IN and Butler and Hamilton counties in OH, and Boone, Kenton, and Campbell counties in KY, and traffic volumes on interstate and local access highways in Greater Cincinnati, OH. There is no significant statistical correlation between mercury measured in adult cicadas and the amount of mercury deposited on the ground or concentrated in the air as a direct result of anthropogenic activities. There may be as yet unidentified biological processes within either the ecosystem or the cicada that affect the amount of mercury measured. This study contributes to the knowledge required to make an informed assessment of the risk to human health posed by mercury emissions in air.