Oceanography of Glacier Bay,Alaska: Implications for biological patterns in a glacial fjord estuary

Alaska, U.S.A, is one of the few remaining locations in the world that has fjords that contain temperate idewater glaciers. Studying such estuarine systems provides vital information on how deglaciation affects oceanographic onditions of fjords and surrounding coastal waters. The oceanographic system of Glacier Bay, Alaska, is of particular interest ue to the rapid deglaciation of the Bay and the resulting changes in the estuarine environment, the relatively high oncentrations of marine mammals, seabirds, fishes, and invertebrates, and the Bay’s status as a national park, where ommercial fisheries are being phased out. We describe the first comprehensive broad-scale analysis of physical and iological oceanographic conditions within Glacier Bay based on CTD measurements at 24 stations from 1993 to 2002. easonal patterns of near-surface salinity, temperature, stratification, turbidity, and euphotic depth suggest that freshwater nput was highest in summer, emphasizing the critical role of glacier and snowmelt to this system. Strong and persistent tratification of surface waters driven by freshwater input occurred from spring through fall. After accounting for seasonal nd spatial variation, several of the external physical factors (i.e., air temperature, precipitation, day length) explained a large mount of variation in the physical properties of the surface waters. Spatial patterns of phytoplankton biomass varied hroughout the year and were related to stratification levels, euphotic depth, and day length. We observed hydrographic atterns indicative of strong competing forces influencing water column stability within Glacier Bay: high levels of freshwater ischarge promoted stratification in the upper fjord, while strong tidal currents over the Bay’s shallow entrance sill enhanced ertical mixing. Where these two processes met in the central deep basins there were optimal conditions of intermediate tratification, higher light levels, and potential nutrient renewal. These conditions were associated with high and sustained hlorophylla levels observed from spring through fall in these zones of the Bay and provide a framework for understanding he abundance patterns of higher trophic levels within this estuarine system.     

A three-dimensional finite-element model of wind effects upon higher harmonics of the internal tide

A non-linear three-dimensional unstructured grid model of the M₂ tide in the shelf edge area off the west coast of Scotland is used to examine the spatial distribution of the M₂ internal tide and its higher harmonics in the region. In addition, the spatial variability of the tidally induced turbulent kinetic energy and associated mixing in the area are considered. Initial calculations involve only tidal forcing, although subsequent calculations are performed with up-welling and down-welling favourable winds to examine how these influence the tidal distribution (particularly the higher harmonics) and mixing in the region. Both short- and long-duration winds are used in these calculations. Tidal calculations show that there is significant small-scale spatial variability particularly in the higher harmonics of the internal tide in the region. In addition, turbulence energy and mixing exhibit appreciable spatial variability in regions of rapidly changing topography, with increased mixing occurring above seamounts. Wind effects significantly change the distribution of the M₂ internal tide and its higher harmonics, with appreciable differences found between up- and down-welling winds and long- and short-duration winds because of differences in mixing and the presence of wind-induced flows. The implications for model validation, particularly in terms of energy transfer to higher harmonics, and mixing are briefly discussed.     

International Association of Geoanalysts' Protocol for the Certification of Geological and Environmental Reference Materials: A Supplement

The International Association of Geoanalysts (IAG) published a protocol for the certification of reference materials in close accord with the International Organisation for Standardisation (ISO) guidelines (Kane et al. 2003). This article supplements that protocol, providing additional discussion of best approaches for pre-selecting laboratories for participation in certification projects. This discussion also makes a distinction between inter-laboratory certifications, where n = 15 is the general standard, and expert laboratory certifications, where a much smaller number of laboratories will be deemed qualified to provide data of the quality needed for certification.     

Linking Ecotourism and Biodiversity Conservation: A Case Study of Doi Inthanon National Park, Thailand

Ecotourism, or tourism that promotes conservation, does not occur in isolation, but as part of an interdependent system. Based on a case study at Doi Inthanon National Park, Thailand, this study outlines a conceptual framework for such a system, placing biodiversity conservation in the context of other major tourism components, including tourists, ecotourism infrastructure, protected areas and local people. In an interactive way, each component affects the conservation of biodiversity. Based on a tourist survey and participant observation, we examine the interrelationships among the key tourism components and potential changes over time. Several environmental, social, economic and educational effects illustrate the complex nature of the ecotourism-conservation relationship. Recommendations to increase conservation benefits from ecotourism are provided.     

Environmental changes in Saginaw Bay,Lake Huron recorded by geolipid contents of sediments deposited since 1800

Changes in organic materials preserved within sediments of Saginaw Bay deposited over the past two centuries record corresponding periods in the environmental history of this part of Lake Huron and its watershed. Sediments deposited since 1940 show an increasingly greater input of aquatic organic matter in response to accelerating cultural eutrophication of Saginaw Bay. Concentrations of fatty acids, sterols, fatty alcohols, and aliphatic hydrocarbons are higher in these modern sediments than in deeper ones. Molecular distributions of these geolipids reflect less aquatic material deeper in the sediments. Prior to 1875, sediment organic matter appears to be diluted by mineral matter from enhanced erosion caused by clearing of the watershed for farming and settlement. During this period there is better preservation of carbonate minerals due to quicker burial. Since 1875, petroleum components comprise over 90% of the total aliphatic hydrocarbon content of these sediments, reflecting the advent and continued existence of chronic, low-level petroleum contamination of this part of the Great Lakes.     

Molybdenum Content of 16 U.S. Geological Survey Standard Rocks

The concentration of molybdenum in 16 U.S. Geological Survey (USGS) standard rocks was determined by a colorimetric procedure using zinc dithiol reagent. The molybdenum content in the rocks was found to range from 0.04 to 37 ppm. The precision of the method is generally better than 10% relative deviation when the molybdenum content is >0.3 ppm. A comparison with values stated in the literature shows that the method is accurate for the range of concentrations determined and the rock types analyzed.     

Size and shape of near-spherical Allegan chondrules

Chondrules were extracted from a disaggregated sample of the Allegan meteorite. Individual chondrules were examined with apparatus incorporating two orthogonal binocular microscopes, and their three major axes measured. Maximum chondrule diameters ranged from 0.15 to 2.75 mm with a peak in distribution between 0.35 and 0.75 mm. The chondrule size distribution was found not to conform to Rosin's law. The chondrules were found to depart from sphericity by only small amounts. The authors still believe that the melting of nebula dust-ball agglomerates by some high-energy event was the most probable mechanism for the formation of chondrules.     

Earthquake recurrence on the Calaveras fault east of San Jose, California

Occurrence of small (3 M_L < 4) earthquakes on two 10-km segments of the Calaveras fault between Calaveras and Anderson reservoirs follows a simple linear pattern of elastic strain accumulation and release. The centers of these independent patches of earthquake activity are 20 km apart. Each region is characterized by a constant rate of seismic slip as computed from earthquake magnitudes, and is assumed to be an isolated locked patch on a creeping fault surface. By calculating seismic slip rates and the amount of seismic slip since the time of the last significant (M 3) earthquake, it is possible to estimate the most likely date of the next (M - 3) event on each patch. The larger the last significant event, the longer the time until the next one. The recurrence time also appears to be increased according to the moment of smaller (2 < M_L < 3) events in the interim. The anticipated times of future larger events on each patch, on the basis of preliminary location data through May 1977 and estimates of interim activity, are tabulated below with standard errors. The occurrence time for the southern zone is based on eight recurrent events since 1969, the northern zone on only three. The 95% confidence limits can be estimated as twice the standard error of the projected least-squares line. Events of M 3 should not occur in the specified zones at times outside these limits. The central region between the two zones was the locus of two events (M = 3.6, 3.3) on July 3, 1977. These events occurred prior to a window based on the three point, post-1969 slip-time line for the central region.

Latitude	Longitude	Depth	Mag.	Target date	Standard error (days)
37°17′± 2′N	121°39′±2′W	5.0 ±2 km	3.0–4.0	7-22-77	22.3
37°26′± 2′N	121°47′±2′W	6.0 ± 2 km	3.0–4.0	9-02-77	8.0

Full-size table