Tracing Legacy Mercury Sources in Aquatic Ecosystems Using Mercury Stable Isotopes.

Mercury (Hg) is a neurotoxic pollutant that exists in both inorganic (Hg0, Hg2+) and organo-metallic (monomethyl mercury: MMHg) chemical forms. Inorganic Hg (IHg) has been released to aquatic environments during its historical use in mining and industry. In these environments IHg can be converted to MMHg, a potent developmental neurotoxin that bioaccumulates in the food web and can pose a risk to humans and wildlife. Therefore, identifying the distribution of legacy IHg sources, and understanding their transformation to MMHg is of great interest. In this dissertation, we report Hg stable isotope ratios in sediment and food webs from North American streams contaminated by legacy Hg sources. In Chapter 2 and 3, we use Hg isotopes in stream and estuarine sediment to fingerprint multiple Hg sources and trace their transport and deposition. In Chapters 4 and 5, we measure Hg isotopes in both sediment and aquatic food webs to identify MMHg formation, degradation and exposure pathways in streams and wetlands contaminated by historical gold and mercury mining. This work demonstrates that Hg stable isotope measurements can be used to trace the spatial and temporal distribution of legacy Hg sources and identify relevant biogeochemical processes and exposure pathways leading to MMHg bioaccumulation in aquatic environments.PHDEarth and Environmental SciencesUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/113515/1/pmdon_1.pd

U.S. political intelligence and American policy on Iran, 1950-1979

This Ph.D. thesis examines United States political intelligence in regard to the regime of Muhammad Reza Shah Pahlavi, the Shah of Iran, the accuracy of this intelligence, and it's influence on American policy from 1950-1979. Based on archival material, declassified documents, and interviews with relevant personalities, this thesis seeks to chronicle nearly three decades of intelligence analysis on the factors governing political stability in Iran, and establish the veracity of this analysis vis-a-vis the historical record. In the early 1950s, American intelligence operatives contributed to the overthrow of the nationalist government in Iran headed by Dr. Muhammad Musaddiq, and the restoration to a position of authority of the Shah. In its exploration of the motives behind the 1953 covert political intervention to unseat Musaddiq, the thesis finds that the Eisenhower administration acted out of a set of Cold War priorities that included the need to maintain cohesion in the Anglo-American special relationship and fears of Iranian neutrality.The United States gained a pliant ally, but one whose power base was tenuous. By the end of the Eisenhower administration, intelligence analysts concluded that, in the absence of significant economic and political reform, the Shah's regime had become so unstable as to virtually guarantee revolutionary change. Acting on a broad consensus among the intelligence community about the regime's weakness, the Kennedy administration sought to bolster the government with limited financial and political support while encouraging reform. American pressure on this front led the Shah, in 1963, to announce the "White Revolution," a six point program for reform designed to shift the monarch's base of support from the traditional ruling elite to the lower classes. The announcement of the "White Revolution" marks a rough watershed in the intelligence-policy relationship in Washington as it pertained to Iran. While American policy makers viewed the program as a progressive step forward, intelligence analysts were inclined to view the Shah's reforms as ill-conceived and, given the lack of meaningful political reform, designed largely to consolidate power in the hands of the Shah. Thus began a period during the Johnson administration where intelligence analysts emphasized the need for the diffusion of power and the inclusion of the middle classes in the decision-making process, while American policy makers placed their hopes for stability in economic determinism.an policy makers placed their hopes for stability in economic determinism. The thesis explores the reasons behind the end ofthe intelligence-policy consensus on Iran and the failure ofthe intelligence community to communicate their position in an effective way. The reasons included the decreasing standing of the intelligence community in the US domestic context, the appearance of enhanced stability in Iran, the multiplicity of opinions within the diplomatic and intelligence reporting system, and most importantly, the changing international strategic environment.The Shah's value as an ally and proxy for American interests increased substantially after the 1967 Arab-Israeli conflict and the announcement, in 1968, that the British would end their presence in the Persian Gulf. The thesis concludes that sensitive analysts within the intelligence community continued to report that the regime in Tehran had failed to institutionalize itself and that the increasing economic prosperity brought about by the oil boom would eventually foster demands for democratization. By contrast, American policy became predicated on the highly personalized and prowestern policies of the Shah, and thus, the continuation of one-man rule in Iran. Consequently, policy makers in the Nixon administration sought to bolster the Shah's regime through unprecedented levels of military and diplomatic support. These policies helped to exacerbate the grievances of the Shah's domestic critics.Meanwhile, intelligence on the viability of the Shah's regime was downgraded as a priority by policy makers. Nevertheless, implicit concerns about the long-term consequences of the Shah's policies and ambitions can be found in much of the intelligence analyses of this period. Additionally, while failing to predict any imminent conflagration in Iran, this reporting did identify many of the factors that would play a decisive role in the 1978 revolution. In exploring these varying degrees of skepticism about the long-term viability of the Shah's regime, the thesis demonstrates that the intelligence community was not entirely surprised by the revolutionary forces that would bring about the downfall of the Pahlavi system, even if the exact identity of these forces were unknown. The work concludes that the intelligence community's tacit understanding of the weaknesses of the Pahlavi system enabled analysts to react more quickly to the Iranian revolution than has been previously supposed

Hydrologic indicators of hot spots and hot moments of mercury methylation potential along river corridors

The authors acknowledge financial support from the National Science Foundation: EAR-1226741 (to M.B.S.) and EAR-1225630 (to J.D.B.), and from the REG Trust (to M.B.S.).The biogeochemical cycling of metals and other contaminants in river-floodplain corridors is controlled by microbial activity responding to dynamic redox conditions. Riverine flooding thus has the potential to affect speciation of redox-sensitive metals such as mercury (Hg). Therefore, inundation history over a period of decades potentially holds information on past production of bioavailable Hg. We investigate this within a Northern California river system with a legacy of landscape-scale 19th century hydraulic gold mining. We combine hydraulic modeling, Hg measurements in sediment and biota, and first-order calculations of mercury transformation to assess the potential role of river floodplains in producing monomethylmercury (MMHg), a neurotoxin which accumulates in local and migratory food webs. We identify frequently inundated floodplain areas, as well as floodplain areas inundated for long periods. We quantify the probability of MMHg production potential (MPP) associated with hydrology in each sector of the river system as a function of the spatial patterns of overbank inundation and drainage, which affect long-term redox history of contaminated sediments. Our findings identify river floodplains as periodic, temporary, yet potentially important, loci of biogeochemical transformation in which contaminants may undergo change during limited periods of the hydrologic record. We suggest that inundation is an important driver of MPP in river corridors and that the entire flow history must be analyzed retrospectively in terms of inundation magnitude and frequency in order to accurately assess biogeochemical risks, rather than merely highlighting the largest floods or low-flow periods. MMHg bioaccumulation within the aquatic food web in this system may pose a major risk to humans and waterfowl that eat migratory salmonids, which are being encouraged to come up these rivers to spawn. There is a long-term pattern of MPP under the current flow regime that is likely to be accentuated by increasingly common large floods with extended duration.PostprintPeer reviewe

Isotopic evidence for mercury photoreduction and retention on particles in surface waters of Central California, USA

Cache Creek (Coast Range, California) and the Yuba River (Sierra Nevada Foothills, California) are two river systems affected by extensive mercury (Hg) contamination due to legacy sources of Hg related to mining. Stable Hg isotope techniques have proven useful for elucidating the complex cycling of Hg within aquatic ecosystems, and we applied these techniques to improve understanding of Hg and methylmercury (MeHg) transformations in these watersheds. Total mercury (THg) concentrations and Hg stable isotope ratios were measured in filtered surface waters and suspended particulate matter collected from 14 sites within the Cache Cr. and Yuba R. watersheds. Filtered surface waters from both watersheds exhibited values of ∆199Hg (0.37‰ to 0.71‰), consistently elevated above those observed in sediments (∆199Hg average = 0.07‰). Associated suspended particulates from these surface water samples displayed a much greater range of values for ∆199Hg (−0.61‰ to 0.70‰), although suspended particulates from the Yuba R. exhibited mostly negative ∆199Hg values (−0.61‰ to 0.10‰). The relationship between ∆199Hg and ∆201Hg in the filtered surface waters and associated suspended particulates was calculated using a bivariate York regression, yielding a slope of 1.57 ± 0.49 (±2SE) for the Yuba R. and 1.40 ± 0.27 (±2SE) for Cache Cr., both within error of the previously reported experimentally-derived slopes for MeHg- and inorganic Hg(II)-photoreduction. This provides isotopic evidence that Hg photoreduction is occurring within these surface waters to a significant degree, and suspended particulate phases are retaining the reduced product of Hg photoreduction, particularly within the Yuba R. The isotopic compositions of filtered surface waters are consistent with the isotopic signatures recorded in biota at low trophic positions within these watersheds, suggesting that the reservoir of Hg incorporated within the biota of these systems is similar to the filter-passing Hg fraction in surface waters

In Pursuit of Improving Airburst and Ground Damage Predictions: Recent Advances in Multi-Body Aerodynamic Testing and Computational Tools Validation

An airburst from a large asteroid during entry can cause significant ground damage. The damage depends on the energy and the altitude of airburst. Breakup of asteroids into fragments and their lateral spread have been observed. Modeling the underlying physics of fragmented bodies interacting at hypersonic speeds and the spread of fragments is needed for a true predictive capability. Current models use heuristic arguments and assumptions such as pancaking or point source explosive energy release at pre-determined altitude or an assumed fragmentation spread rate to predict airburst damage. A multi-year collaboration between German Aerospace Center (DLR) and NASA has been established to develop validated computational tools to address the above challenge

Evaluation of the model of music education of future teachers of primary education

Cilj je istraživanja evaluacija postojećega modela glazbenoga obrazovanja budućih učitelja i svojstava nastave glazbe na učiteljskim studijima u Hrvatskoj. Istraživanje je provedeno anketiranjem studenata učiteljskog studija na Učiteljskom fakultetu u Osijeku (N=307), Učiteljskom fakultetu u Zagrebu (N=344) i Odjelu za izobrazbu učitelja i odgojitelja Sveučilišta u Zadru (N=121) te među nastavnicima glazbe (N=12) na učiteljskim studijima u Hrvatskoj. Postojeći model glazbenoga obrazovanja budućih učitelja evaluiran je jednim stupnjem iznad prosječne ocjene, a između ocjena studenata i nastavnika nema značajne razlike. Utvrđena je značajna razlika u evaluaciji modela kod studenata s različitih fakulteta. Evaluacija materijalnih uvjeta pokazala je kako je opremljenost učionica za nastavu glazbe dobra osim u nedovoljnoj opremljenosti glazbenim instrumentima koje bi studenti mogli upotrebljavati tijekom nastavnoga procesa. U radu se predlažu moguća rješenja proizašla iz ovog istraživanja koja bi mogla dovesti kvalitativnih promjena u glazbenom obrazovanju budućih učitelja.The aim of this research is to evaluate the existing model of music education for future teachers as well as the characteristics of music teaching at various teaching study programmes in Croatia. A survey has been conducted among students at the Faculty of Education in Osijek (N = 307), the Faculty of Teacher Education in Zagreb (N = 344), the Department for Education of Teachers and Pre-school Teachers of the University of Zadar (N = 121), and among music teachers (N = 12) at teacher study programmes in Croatia. The existing model of music education for future teachers has been evaluated as better than average, both by students and teachers alike. A significant difference in model evaluation has been established among students from different faculties. The evaluation of material conditions has shown that music classrooms are well-equipped, except when it comes to musical instruments that could be used by students in lessons. The paper proposes possible solutions, resulting from the research, which could lead to qualitative changes in music education of future teachers

23 High Redshift Supernovae from the IfA Deep Survey: Doubling the SN Sample at z>0.7

We present photometric and spectroscopic observations of 23 high redshift supernovae spanning a range of z=0.34-1.03, 9 of which are unambiguously classified as Type Ia. These supernovae were discovered during the IfA Deep Survey, which began in September 2001 and observed a total of 2.5 square degrees to a depth of approximately m=25-26 in RIZ over 9-17 visits, typically every 1-3 weeks for nearly 5 months, with additional observations continuing until April 2002. We give a brief description of the survey motivations, observational strategy, and reduction process. This sample of 23 high-redshift supernovae includes 15 at z>0.7, doubling the published number of objects at these redshifts, and indicates that the evidence for acceleration of the universe is not due to a systematic effect proportional to redshift. In combination with the recent compilation of Tonry et al. (2003), we calculate cosmological parameter density contours which are consistent with the flat universe indicated by the CMB (Spergel et al. 2003). Adopting the constraint that Omega_total = 1.0, we obtain best-fit values of (Omega_m, Omega_Lambda)=(0.33, 0.67) using 22 SNe from this survey augmented by the literature compilation. We show that using the empty-beam model for gravitational lensing does not eliminate the need for Omega_Lambda > 0. Experience from this survey indicates great potential for similar large-scale surveys while also revealing the limitations of performing surveys for z>1 SNe from the ground.Comment: 67 pages, 12 figures, 12 tables, accepted for publication in the Astrophysical Journa

Methylmercury degradation and exposure pathways in streams and wetlands impacted by historical mining

The authors acknowledge financial support from the National Science Foundation: EAR-1226741 (to M.B.S.) and EAR-1225630 (to J.D.B.).Monomethyl mercury (MMHg) and total mercury (THg) concentrations and Hg stable isotope ratios (δ202Hg and Δ199Hg) were measured in sediment and aquatic organisms from Cache Creek (California Coast Range) and Yolo Bypass (Sacramento Valley). Cache Creek sediment had a large range in THg (87 to 3870 ng/g) and δ202Hg (− 1.69 to − 0.20‰) reflecting the heterogeneity of Hg mining sources in sediment. The δ202Hg of Yolo Bypass wetland sediment suggests a mixture of high and low THg sediment sources. Relationships between %MMHg (the percent ratio of MMHg to THg) and Hg isotope values (δ202Hg and Δ199Hg) in fish and macroinvertebrates were used to identify and estimate the isotopic composition of MMHg. Deviation from linear relationships was found between %MMHg and Hg isotope values, which is indicative of the bioaccumulation of isotopically distinct pools of MMHg. The isotopic composition of pre-photodegraded MMHg (i.e., subtracting fractionation from photochemical reactions) was estimated and contrasting relationships were observed between the estimated δ202Hg of pre-photodegraded MMHg and sediment IHg. Cache Creek had mass dependent fractionation (MDF; δ202Hg) of at least − 0.4‰ whereas Yolo Bypass had MDF of + 0.2 to + 0.5‰. This result supports the hypothesis that Hg isotope fractionation between IHg and MMHg observed in rivers (− MDF) is unique compared to + MDF observed in non-flowing water environments such as wetlands, lakes, and the coastal ocean.PostprintPeer reviewe

First all-sky search for continuous gravitational waves from unknown sources in binary systems

We present the first results of an all-sky search for continuous gravitational waves from unknown spinning neutron stars in binary systems using LIGO and Virgo data. Using a specially developed analysis program, the TwoSpect algorithm, the search was carried out on data from the sixth LIGO science run and the second and third Virgo science runs. The search covers a range of frequencies from 20 Hz to 520 Hz, a range of orbital periods from 2 to ∼2,254  h and a frequency- and period-dependent range of frequency modulation depths from 0.277 to 100 mHz. This corresponds to a range of projected semimajor axes of the orbit from ∼0.6 × 10[superscript −3]  ls to ∼6,500  ls assuming the orbit of the binary is circular. While no plausible candidate gravitational wave events survive the pipeline, upper limits are set on the analyzed data. The most sensitive 95% confidence upper limit obtained on gravitational wave strain is 2.3 × 10[superscript −24] at 217 Hz, assuming the source waves are circularly polarized. Although this search has been optimized for circular binary orbits, the upper limits obtained remain valid for orbital eccentricities as large as 0.9. In addition, upper limits are placed on continuous gravitational wave emission from the low-mass x-ray binary Scorpius X-1 between 20 Hz and 57.25 Hz.National Science Foundation (U.S.)United States. National Aeronautics and Space AdministrationCarnegie TrustDavid & Lucile Packard FoundationResearch CorporationAlfred P. Sloan Foundatio