Correcting the errors from variable sea salt retention and water of hydration in loss on ignition analysis: Implications for studies of estuarine and coastal waters

The standard technique of determining the concentrations of total suspended solids (TSSs), particulate inorganic matter (PIM), and particulate organic matter (POM) by filtration with glass fiber filters is subject to an error or bias from sea salt plus water of hydration retention, when applied to saline waters. The sea salt plus water of hydration retention by the filters occurs even after washing the filter with 300 ml of deionized water, a greater volume than any wash recommended in the literature. We determined that the mass retention on a glass fiber filter, at a given salinity, is essentially constant, no matter the volume of seawater passed through the filter. We also determined that the sea salt plus water of hydration retention on glass fiber filters is directly proportional to the salinity of the seawater filtered. Sea salt plus water of hydration retention causes an overestimate of TSS; sea salt retention causes an overestimate of PIM; volatilization of water of hydration causes an overestimate of POM. Thus a correction curve is required for sea salt and water of hydration errors in the determination of TSS and PIM. Corrected POM comes from the difference between the two. Also, filter blanks (procedural control filters), run with deionized (DI) water rather than the seawater sample, are required to correct for possible filter mass loss during the analysis. We demonstrate correction curves for sea salt plus water of hydration retention for Whatman GF/F filters, 47 mm diameter, utilizing the methods of the APHA Manual, Standard Methods for the Examination of Water and Wastewater. Application of other glass fiber filter types or an analytical technique differing significantly from that employed here requires a different correction curve for retention of sea salt and water of hydration. These methods can be used to reanalyze older data on PIM, POM, and TSS.We apply these corrections to PIM and POM data from the northern Gulf of Mexico and examine the interactions of these filter corrections with corrections for structural water volatilization from suspended clay minerals in the determinations of PIM and POM. We analyze published data on PIM and POM determinations and their application to remote sensing. We conclude that sea salt and water of hydration retention on filters has an adverse effect on remote-sensing algorithms inverting radiance reflectance to estimate concentrations of suspended matter.     

The Cognitive Load of Geographic Information

Multimedia presentations that combine verbal and visual information are increasingly becoming important methods for communicating geographic information. This article discusses literature related to cognitive load theory (CLT) and offers ideas on how this theory might be used for geography education and research. By considering the limitations of the human mind, CLT offers geographers a way to assess critical components of the spatial learning processes. Methods for measuring cognitive load and reducing overloads are discussed within a map context. It is argued that managing the cognitive load experienced by learners is the key to representing geographic information.     

Abundance of brown trout as related to littoral zone gradient in Lakes Te Anau and Manapouri,New Zealand

Adult brown trout (Salmo trutta L.) in lakes are primarily littoral/benthic foragers. We predicted that the distribution of adult brown trout in lakes would be shaped by foraging demands, and that they would be more abundant in gently sloping littoral areas, that is, littoral areas that have a greater space available to support benthic foraging habitats. To address this hypothesis, we measured abundance of brown trout among littoral areas with different gradients in Lakes Te Anau and Manapouri. There was a significant negative relationship between littoral zone gradient and relative abundance (CPUE) of adult brown trout. This result supports the hypothesis that brown trout aggregate in littoral areas with greater amounts of foraging habitat in Fiordland lakes.     

Two new species of Pseudostomella (Gastrotricha: Macrodasyida) with scaled triancres from the east coast of Australia

Two new species of Pseudostomella from North Stradbroke Island, Australia, P. klauserae n. sp. and P. megapalpator n. sp., are characterised by scaled triancres, cuticular structures that until now were known only from one other member of the genus. The structure of the scaled triancres in both species is new: the triancre base is diamond‐ or triangular‐shaped with three shafts that arise to form feather‐like scales. P. klauserae n. sp. is characterised by scales arising from a diamond‐shaped triancre base, the distribution of cephalic papillae, and the abundance and distribution of anterior and lateral adhesive tubes. P. megapalpator n. sp. is distinguished by scales arising from a rounded‐triangular triancre base, large dorsal, digitiform papillae, and ventral adhesive tubes. The presence of two new species with scaled triancres allows for the formation of a novel species complex within the genus. An amended key to the species is included.     

Estimating Deep Seafloor Interface and Volume Roughness Parameters Using the Multibeam-Hydrosweep System

Utilizing a hull-mounted, multinarrow beam echosounder onboard RV Polarstern, we measured variation of acoustic backscatter with incidence angles at two different sites in the Southern Oceans (Agulhas Plateau and the Riiser Larsen Sea). We modeled the data, using a composite roughness model, including water-sediment interface roughness and sediment volume roughness parameters. The model effectively uses the near normal incidence angle backscatter to determine the seafloor interface roughness parameters employing Helmholtz-Kirchhoff theory. Beyond 20° incidence angles, an application of Rayleigh-Rice theory is made by using a necessary splicing technique (combining both of the theories at 20° incidence angle). The estimated interface and volume roughness parameters are found to be in accordance with the known area geology.     

Marine radiocarbon reservoir corrections (∆R) for Chesapeake Bay and the Middle Atlantic Coast of North America

Radiocarbon dates from known age, pre-bomb eastern oyster (Crassostrea virginica) shells provide local marine reservoir corrections (?R) for Chesapeake Bay and the Middle Atlantic coastal area of eastern North America. These data suggest subregional variability in ?R, ranging from 148 ± 46 ¹⁴C yr on the Potomac River to ? 109 ± 38 ¹⁴C yr at Swan Point, Maryland. The ?R weighted mean for the Chesapeake's Western Shore (129 ± 22 ¹⁴C yr) is substantially higher than the Eastern Shore (? 88 ± 23 ¹⁴C yr), with outer Atlantic Coast samples falling between these values (106 ± 46 and 2 ± 46 ¹⁴C yr). These differences may result from a combination of factors, including ¹⁴C-depleted freshwater that enters the bay from some if its drainages, ¹⁴C-depleted seawater that enters the bay at its mouth, and/or biological carbon recycling. We advocate using different subregional ?R corrections when calibrating ¹⁴C dates on aquatic specimens from the Chesapeake Bay and coastal Middle Atlantic region of North America.     

Information systems playground—the target infrastructure

The Target infrastructure has been specially built as a storage and compute infrastructure for the information systems derived from Astro-WISE. This infrastructure will be used by several applications that collaborate in the area of information systems within the Target project. It currently consists of 10 PB of storage and thousands of computational cores. The infrastructure has been constructed based on the requirements of the applications. The storage is controlled by the Global Parallel File System of IBM. This file system takes care of the required flexibility by combining storage hardware with different characteristics into a single file system. It is also very scalable, which allows the system to be extended into the future, while replacing old hardware with new technology.     

Primary productivity in the German Bight (1994–1996)

Within the KUSTOS program (Coastal Mass and Energy Fluxes-the Land-Sea Transition in the Southeastern North Sea) 28 to 36 German Bight stations were seasonally surveyed (summer 1994, spring 1995, winter 1995–1996) for light conditions, dissolved inorganic nutrient concentrations, chlorophylla (chla), and photosynthesis versus light intensity (P:E) parameters. Combining P:E curve characteristics with irradiance, attenuation, and chlorophyll data resulted in seasonal estimates of the spatial distribution of total primary production. These data were used for an annual estimate of the total primary production in the Bight. In winter 1996 the water throughout the German Bight was well mixed. Dissolved inorganic nutrient concentrations were relatively high (nitrogen [DIN], soluble reactive phosphorus [SRP], and silicate [Si]: 23, 1, and 10 μM, respectively). Chla levels generally were low (< 2 μg l⁻¹) with higher concentrations (4–16 μg l⁻¹) in North Frisian coastal waters. Phytoplankton was limited by light. Total primary production averaged 0.2 g C m⁻² d⁻¹. Two surveys in April and May 1995 captured the buildup of a strong seasonal thermo-cline accompained by the development of a typical spring diatom bloom. High nutrient levels in the mixed layer during the first survey (DIN, SRP, and Si: 46, 0.45, and 11 μM, respectively) decreased towards the second survey (DIN, SRP, and Si: 30.5, 0.12, and 1.5 μM, respectively) and average nutrient ratios shifted further towards highly imbalanced values (DIN:SRP: 136 in survey 1, 580 in survey 2; DIN:Si: 13.5 in survey 1, 96 in survey 2). Chla ranged from 2 to 16 μg l⁻¹ for the first survey and rose to 12–50 μg l⁻¹ in the second survey. Phytoplankton in nearshore areas continued to be light limited during the second survey, while data from the stratified regions in the open German Bight indicates SRP and Si limitation. Total primary production ranged from 4.0 to 6.3 g C m⁻² d⁻¹. During summer 1994 a strong thermal stratification was present in the German Bight proper and shallow coastal areas showed unusually warm (up to 22°C), mixed waters. Chla concentrations ranged from 2 to 18 μg l⁻¹. P:E characteristics were relatively high despite the low nutrient regime (DIN, SRP, and Si: 2, 0.2, and 1.5 μM, respectively), resulting in overall high total primary production values with an average of 7.7 g C m⁻² d⁻¹. Based on the seasonal primary production estimates of the described surveys a budget calculation yielded a total annual production of 430 g C m⁻² yr⁻¹ for the German Bight.     

Evolution of the Mount Woods Inlier, northern Gawler Craton, Southern Australia: an integrated structural and aeromagnetic analysis

Structural mapping integrated with interpretation and forward modelling of aeromagnetic data form complimentary and powerful tools for regional structural analysis because both techniques focus on architecture and overprinting relationships. This approach is used to constrain the geometry and evolution of the sparsely exposed Mount Woods Inlier in the northern Gawler Craton. The Mount Woods Inlier records a history of poly-phase deformation, high-temperature metamorphism, and syn- and post-orogenic magmatism between ca. 1736 and 1584 Ma. The earliest deformation involved isoclinal folding, and the development of bedding parallel and axial planar gneissic foliation (S₁). This was accompanied by high-temperature, upper amphibolite to granulite facies metamorphism at ca. 1736 Ma. During subsequent north–south shortening (D₂), open to isoclinal south–southeast-oriented F₂ folds developed as the Palaeoproterozoic successions of the inlier were thrust over the Archaean nuclei of the Gawler Craton. The syn-D₂ Engenina Adamellite was emplaced at ca. 1692 Ma. The post-D₂ history involved shear zone development and localised folding, exhumation of metamorphic rocks, and deposition of clastic sediments prior to the emplacement of the ca. 1584 Ma Granite Balta Suite. The Mount Woods Inlier is interpreted as the northern continuation of the Kimban Orogen.     

Fe,Ti ordering and octahedral distortions in acentric neptunite: Temperature dependent X-ray and neutron structure refinements and Mössbauer spectroscopy

Single-crystal X-ray and neutron structure refinements carried out on neptunite (KNa₂Li(Fe, Mg, Mn)₂Ti₂Si₈O₂₄) from San Benito, California at various temperatures (neutrons: 15 K and 293 K; X-rays: 110 K, 293 K and 493 K) indicate that this mineral crystallizes in the acentric space group Cc (T=293K: a=16.427 Å, b=12.478 Å, c=9.975 Å, = 115.56°, Z=4, V=1844.53 ų) due to ordering of octahedrally coordinated metals (Ti, Fe, Mn, Mg). In the neptunite structure, Ti and (Fe, Mn, Mg) octahedra share edges to form chains that run along [110] and [110]. These chains are, in turn, linked through shared corners along [001]. The resulting octahedral framework is interwoven by a similar [Si₈O₂₂] tetrahedral framework. Li, Na and K occupy 6-, 8- and 10- coordinated sites within the framework. The metal-containing polyhedra show strong distortions at all temperatures. In particular, Ti exhibits a strong off-center displacement (0.25 Å) within its octahedron, leading to four Ti-O distances of 2.0 Å, one of 2.2 Å and one of 1.7 Å. The displaced Ti position is in good agreement with a position that minimizes differences between ionic bond strengths and is interpreted as an energy minimum in an ionic potential model. Mössbauer spectra collected at 77 K, 293 K and 400 K indicate all Fe to be present as octahedral Fe²⁺. Although two distinct Fe positions were found in the structure, 77 K and 293 K spectra display only one quadrupole doublet. Two Fe sites can only be resolved in the 400 K spectrum. It is suggested that the temperature dependence of octahedral edge distortions is responsible for the separation of the Mössbauer doublets.