Profiles of Fecal Porphyrins in River Otters Following the Exxon Valdez Oil Spill

Median levels of Coproporphyrin III (Copro III) in fecal samples of river otters (Lontra canadensis) collected from an oiled area in Prince William Sound, Alaska, USA, during 1990 were significantly higher than in samples collected from the same oiled area during 1996 (p=0.011, one way analysis of variance), a nonoiled reference area in Prince William Sound during 1996 (p=0.002) and a reference area in southeast Alaska during 1998 (p=0.004). An overall test of significance that combined probabilities from the statistical analysis of this porphyrin study with those from other biomarker studies revealed a significant difference in physiological response of river otters between oiled and nonoiled areas of the Sound for 1990 (p < 0.01). We demonstrated that changes in levels of fecal porphyrins may serve as a biomarker that may contribute to a health assessment of wild river otters.     

Retrospective analysis: bile hydrocarbons and histopathology of demersal rockfish in Prince William Sound,Alaska, after the Exxon Valdez oil spill

Demersal rockfish are the only fish species that have been found dead in significant numbers after major oil spills, but the link between oil exposure and effect has not been well established. After the 1989 Exxon Valdez oil spill in Prince William Sound, Alaska, several species of rockfish (Sebastes spp.) from oiled and reference sites were analyzed for hydrocarbon metabolites in bile (1989-1991) and for microscopic lesions (1990 and 1991). Biliary hydrocarbons consistent with exposure to Exxon Valdez oil were elevated in 1989, but not in 1990 or 1991. Significant microscopic findings included pigmented macrophage aggregates and hepatic megalocytosis, fibrosis, and lipid accumulation. Site differences in microscopic findings were significant with respect to previous oil exposure in 1991 (P=0.038), but not in 1990. However, differences in microscopic findings were highly significant with respect to age and species in both years (P<0.001). We conclude that demersal rockfish were exposed to Exxon Valdez oil in 1989, but differences in microscopic changes in 1990 and 1991 were related more to age and species differences than to previous oil exposure.     

Restoration of oiled mussel beds in Prince William Sound, Alaska

Natural loss of hydrocarbons was often low from mussel (Mytilus trossulus) beds (which were typically not cleaned after the Exxon Valdez oil spill), thus this habitat remained a long-term source of oil. Consequently, experimental restoration of nine contaminated beds was attempted in 1994; mussels were removed, contaminated surface sediment was replaced (33 metric tons), and original mussels were returned. Hydrocarbon concentrations and mussel populations were monitored for 5 years thereafter. Post-restoration mussel population fluctuations were indistinguishable from regional changes. Increased short-term oil loss was apparent, but long-term (5 year) improvement was equivocal and difficult to distinguish from natural losses. By 1999, oil concentrations in mussels were typically at baseline levels in restored and oiled reference beds; concentrations in replaced sediment were elevated in one third of restored beds, indicating recontamination from underlying or surrounding sediment. Our results suggest mussel relocation is feasible but suggest oil might more effectively be removed from sediment mechanically or chemically than manually.     

Relocations of Earthquakes (1899–1917) in South-Central Alaska

I have relocated 18 earthquakes occurring in the south-central Alaska region between 1899 and 1917 using a bootstrap relocation technique. Locations of events within the Yakutat region suggest that the 1899 sequence began on 4 September with a M_S = 7.9 event within the area of the Pamplona fault zone/western Transition fault zone, rupturing the western portion of the North American/Pacific plate interface. A M_S = 7.4 event on 10 September appears to have ruptured the offshore portion of the plate interface to the east of the 4 September event. This was followed by a M_S = 8.0 event that likely ruptured the onshore and down-dip portion of the plate interface. A M_S = 7.0 event in 1908 may have ruptured a small portion of the plate interface between the 4 September and 10 September events. Events occurring between 1911 and 1916 in the Prince William Sound region appear to be slab events occurring in similar locations to more recent seismicity. Within the Kodiak region the 1900 earthquake of M_S = 7.7 has a location consistent with the rupture of the Kodiak asperity which also ruptured during the 1964 great Alaska earthquake. Other large magnitude Kodiak events appear to be associated with regions of recent seismicity, including the Karluk Lake area of southwestern Kodiak Island and the Albatross Basin located offshore southeast of Kodiak Island. Space-time seismicity patterns since 1899 indicate that magnitude 6 to7 events have occurred with regularity in the Kodiak Island region; that there has been a lack of magnitude ≥ 6 events in the Prince William Sound region since 1964, and that the Yakutat region has remained notably quiescent at the magnitude ≥ 6 level.     

Atmospheric and tidal forcing of the exchange between Prince William Sound and the Gulf of Alaska

Current meter data from a series of oceanographic moorings spanning a total of five years was analyzed to quantify the tidal and subtidal exchange of water between Prince William Sound and the adjacent continental shelf in the northern Gulf of Alaska. Velocity profiles were used to quantify the exchange in terms of a transport through each of the two largest passages: Montague Strait and Hinchinbrook Entrance. Buoy wind and atmospheric pressure observations, as well as bottom pressure records, are then used to elucidate the role of atmospheric forcing on the exchange.An EOF analysis shows that the barotropic component accounts for 62% or more of the variance in the velocity profiles even after tides are removed by low-pass filtering, and thus the analysis is concerned primarily with depth-integrated transport. The estimated depth-integrated transport can reach ±0.6 Sv in Montague Strait, and ±1.5 Sv in Hinchinbrook Entrance. The largest fluctuations occur in response to the semidiurnal tides. Transport variations on subtidal time scales, which can reach −0.2 Sv in Montague Strait, and +0.6 Sv in Hinchinbrook Entrance, are shown by a frequency domain analysis to be dominated by easterly wind stress events which occur at periods of 2–5 days in both summer and winter. Atmospheric pressure has much less impact on transport, but there is some evidence that it might play a small role on time scales of a few weeks.Bottom pressure records suggest that easterly wind events set up a sea level height gradient in Hinchinbrook Entrance such that it tilts up to the east, which under geostrophy drives a barotropic flow into Prince William Sound. The same winds also raise the sea level in Hinchinbrook Entrance relative to Montague Strait, encouraging an outflow there in agreement with the ADCP observations. There is no evidence that the wind drives a vertically sheared bi-directional flow in either entrance, as has been observed in some estuaries. It is hypothesized that the lack of such a flow is possible because Prince William Sound has two major connections to the shelf, which alters the mass conservation requirement for each passage when compared to a system with just one entrance.     

Using tolerance intervals to assess recovery of mussel beds impacted by the Exxon Valdez oil spill

Polycyclic aromatic hydrocarbons (PAH) have been measured in mussel tissues in early spring and summer since 1993 throughout Prince William Sound (PWS) and the Gulf of Alaska (GOA). Season-specific thresholds were established at reference sites to identify ‘above background’ total PAH levels. Thresholds were estimated using one-sided 99% tolerance limits. Thresholds were similar across reference sites but differed by an order of magnitude across seasons. Trends in total PAH since 1998 were assessed for sites impacted by the 1989 Exxon Valdez oil spill or the Alyeska Marine Terminal. Summer samples exhibited no trends; early spring samples declined. In early spring, all sites were judged ‘recovered’ by 2004; in summer, one site in western Prince William Sound and two in the western GOA exceeded thresholds by 11 ng/g dry weight or less. Robust estimation methods prevented bias from observations affected by unknown releases or laboratory errors.     

Long term monitoring for oil in the Exxon Valdez spill region

In the aftermath of the 1989 Exxon Valdez oil spill, a Long Term Environmental Monitoring Program (LTEMP) has been regularly sampling mussels (and some sediments) for polycyclic aromatic and saturated hydrocarbons (PAH and SHC) at sites in Port Valdez, Prince William Sound, and the nearby Gulf of Alaska region. After 1999, a decreasing trend appears in total PAH (TPAH) in tissues at all sites with current values below 100 ng/g dry weight (many below 50 ng/g). Currently, most samples reflect a predominantly dissolved-phase signal. This new low in TPAH likely represents ambient background levels. Synchrony in TPAH time-series and similarities in the hydrocarbon signatures portray regional-scale dynamics. The five inner Prince William Sound sites show similar composition and fluctuations that are different from the three Gulf of Alaska sites. The two Port Valdez sites represent a unique third region primarily influenced by the treated ballast water discharge from the Alyeska Marine Terminal. Prince William Sound has reverted to a stable environment of extremely low level contamination in which local perturbations are easily detected.     

Coseismic slip in the 1964 Prince William Sound earthquake: A new geodetic inversion

The 1964 Prince William Sound earthquake (March 28, 1964;M _w =9.2) caused crustal deformation over an area of approximately 140,000 km² in south central Alaska. In this study geodetic and geologic measurements of this surface deformation were inverted for the slip distribution on the 1964 rupture surface. Previous seismologic, geologic, and geodetic studies of this region were used to constrain the geometry of the fault surface. In the Kodiak Island region, 28 rectangular planes (50 by 50 km each) oriented 218°N, with a dip varying from 8^o nearest the Aleutian trench to 9^o below Kodiak Island, define the rupture surface. In the Prince William Sound region 39 planes with variable dimensions (40 by 50 km near the trench, 64 by 50 km inland) and orientation (218°N in the west and 270°N in the east) were used to approximate the complex faulting. Prior information was introduced to constrain offshore dip-slip values, the strike-slip component, and slip variation between adjacent planes. Our results suggest a variable dip-slip component with local slip maximums occurring near Montague Island (up to 30 m), further to the east near Kayak Island (up to 14 m), and trenchward of the northeast segment of Kodiak Island (up to 17m). A single fault plane dipping 30°NW, corresponding to the Patton Bay fault, with a slip value of 8 m modeled the localized but large uplift on Montague Island. The moment calculated on the basis of our geodetically derived slip model of 5.0×10²⁹ dyne cm is 30% less than the seismic moment of 7.5×10²⁹ dyne cm calculated from long-period surface waves (Kanamori, 1970) but is close to the seismic moment of 5.9×10²⁹ dyne cm obtained byKikuchi andFukao (1987).     

葛利普：一个世纪的回望——谨以此文纪念中国地质学会成立100周年及其创建者之一葛利普教授

葛利普（Amadeus William Grabau），美国地质学家，著名的地层学、古生物学家，其最后的26年在中国度过，是近代以来我国从事地质研究和教育的著名地质学家。他是中国近现代地质学的主要奠基者之一，也是中国最早的科学协会—中国地质学会的早期创始人之一，为中国近现代地质事业作出卓越贡献。在华期间，葛利普先生先后出版大量论文、专著，内容不仅涉及中国的区域地质，也建立起全球构造理论。基于归纳总结北美、欧洲以及亚洲的资料，20世纪30年代早期他提出“脉动理论”，确立了全球海平面升降的规律，并建立起基于海进、海退规律为基础的古生代构造-地层划分方案，成为现今层序地层学的基础；基于大陆漂移假说，分析演绎并建立“极控理论”，强调地壳的大规模水平运动，强调地槽的形成与水平构造运动有关，形成了原始的俯冲与海底扩张思想的萌芽。脉动理论和极控理论分别论述了地球表层的垂直运动和水平运动，两个理论互为补充，通过构造事件相联系，形成统一的葛利普的整体地球观。葛利普先生也是大陆漂移的热情支持者和推广者，为板块构造理论的出现发挥了重要作用，他灵活的归纳和演绎贯穿其科学生涯的始终。他身残志坚，身处绝境而仍笔耕不辍；他生命不息、奋斗不止的精神值得我们永远学习、敬仰和传承。