Mapping of benthic enrichment patterns in Narragansett Bay,Rhode Island

A synoptic reconnaissance survey was performed over a five-day period in August 1988 to assess benthic habitat quality throughout Narragansett Bay, Rhode Island, using REMOTS^® sediment-profile photography and analysis in combination with measurements of the levels ofClostridium perfringens spores (a fecal indicator) in sediments. Three main areas of degraded benthic habitat quality related to either excessive organic enrichment or physical disturbance were identified based solely on the REMOTS^® analysis: the Providence River Reach, Greenwich Bay and its associated coves and harbors, and an area located along the southwest side of Prudence Island. Sediments at many stations in these areas exhibited shallow apparent redox-potential discontinuity (RPD) depths, high apparent oxygen demand, and low-order benthic successional stages. ElevatedClostridium perfringens spore counts in surface sediments were attributed to inputs from wastewater treatment facilities. The highest spore counts occurred at the head of the bay, where wastewater treatment discharges and associated combined sewer overflows are numerous. Using data from the REMOTS^® analysis and the sediment inventory ofC. perfringens spores, a distinction was made between organic enrichment of the bottom from sewage, versus nonsewage enrichment or physical disturbance. The combination of techniques employed in this investigation could be used to design more efficient monitoring programs to assess eutrophication effects in estuaries and determine the effectiveness of regulatory or management initiatives to reduce organic overenrichment of benthic habitats.     

A 50-year record of NO<Subscript>x</Subscript> and SO<Subscript>2</Subscript> sources in precipitation in the Northern Rocky Mountains,USA

Ice-core samples from Upper Fremont Glacier (UFG), Wyoming, were used as proxy records for the chemical composition of atmospheric deposition. Results of analysis of the ice-core samples for stable isotopes of nitrogen (δ¹⁵N, ) and sulfur (δ³⁴S, ), as well as and deposition rates from the late-1940s thru the early-1990s, were used to enhance and extend existing National Atmospheric Deposition Program/National Trends Network (NADP/NTN) data in western Wyoming. The most enriched δ³⁴S value in the UFG ice-core samples coincided with snow deposited during the 1980 eruption of Mt. St. Helens, Washington. The remaining δ³⁴S values were similar to the isotopic composition of coal from southern Wyoming. The δ¹⁵N values in ice-core samples representing a similar period of snow deposition were negative, ranging from -5.9 to -3.2 ‰ and all fall within the δ¹⁵N values expected from vehicle emissions. Ice-core nitrate and sulfate deposition data reflect the sharply increasing U.S. emissions data from 1950 to the mid-1970s.     

Lamprophyric lavas in the Colima graben,SW Mexico

The Colima graben, located in SW Mexico, is one of three grabens which intersect about 50 km SSW of Guadalajara, forming a triple junction. The 90 km long, 20–60 km wide Colima graben represents a N-S rift of the E-W trending Mexican Volcanic Belt. Since the Early Pliocene, the Colima graben has served as a locus for the eruption of alkaline lavas, the most recent of which are basanites and minettes erupted from Late Pleistocene cinder cones (Luhr and Carmichael 1981). In this paper, we report on older alkaline lavas which crop out in the graben's walls. These rocks include phlogopite- and hornblende-bearing lamprophyres, a phlogopite-kalsilite-ankaratrite, and high-K andesites. These lavas crop out throughout the Colima graben area, and are intimately associated with calc-alkaline lavas in the field. Compared to these, the alkaline rocks are strikingly enriched in the incompatible elements, particularly Ba, Sr, P, and the LREE. Unlike the younger Late Pleistocene alkaline cinder cone lavas, most of the graben wall lamprophyres and the high-K andesites represent magmas that appear to have undergone significant evolution since their generation, including fractionation, crustal contamination, and possible magma mixing. Least-squares modeling indicates that the cinder cone minettes represent reasonable parental magmas for the graben lamprophyres. The occurrence of these alkaline lavas in an active calc-alkaline volcanic arc is unusual, and we suggest that they are a manifestation of the rifting processes which produced the Colima graben.     

Two magmatic series with island arc affinities within the vourinos ophiolite

Within the Vourinos ophiolite evidence of two magmatic series has been preserved in cognate cumulates and in effusive and hypabyssal rocks, which constitute the earlier Krapa sequence and the younger Asprokambo sequence. The Asprokambo dyke basic magmas which are poor in incompatible elements and relatively Ni and Cr rich, bear some resemblance to very low Ti basalts (transitional to boninites) found in subduction related arcs or interarc basins. Krapa series magmas from sills, massive and pillow lavas are best equated with low-K tholeiites of island arc suites. Compositions of Al- and Ti- poor Cpx in lavas from both series are comparable to those in island arc basalts, the Asprokambo Cpx being richer in Ca and Cr than those from Krapa.The large volume of cumulates from the Krapa sequence displays the following crystallization order: Ol±Sp, Cpx, Pl±Opx, Mt. Periodic influx of fresh magma batches into the magma chamber occurred mainly during the formation of the lower cumulates (wehrlite, Ol-clinopyroxenite and melagabbro). The upper cumulates, gabbronorite and leucogabbronorite with minor Mt-bearing gabbronorite, crystallized in the upper levels of a magma chamber which became progressively smaller with time. In the Asprokambo sequence, Ol+Sp, Opx, Cpx, PI and Amph are the successively crystallizing phases. The ortho to heteradcumulates consist of websterite, Pl-websterite, gabbronorite, amphibole bearing leuconorite, diorite and granophyre. In cumulates, especially in the lower Krapa sequence, significant subsolidus reaction was probably induced by the persistence of high geothermal gradients linked to continuous magmatism. Petrological features indicate that the evolution of the Krapa series is more compatible with an intermediate fractional/equilibrium crystallization history in an initially open system, whereas nearly perfect fractional crystallization in closed system may have occurred in the small Asprokambo magma chambers. Chemical variations in the lavas of both series can be explained in terms of crystallization of the observed cumulates. Significantly, the Asprokambo intrusives have igneous Mg-hornblende and vanadium bearing, chromian, aluminous titaniferous magnetite, crystallization of which is responsible for the calcalkaline evolutionary trend of these rocks. Major and trace element modelling necessitates a two stage model for the petrogenesis of the Vourinos parental melts, involving high-degree remelting of previously depleted mantle sources favoured by the influx of subduction derived hydrous fluids. The primary magmas parental to the Krapa and Asprokambo series could have been derived respectively by 20 and 30% equilibrium partial fusion of variably depleted lherzolitic sources, leaving residua having a harzburgitic to dunitic composition.     

Gratkorn: A benchmark locality for the continental Sarmatian s.str. of the Central Paratethys

This paper presents one of the richest and most complete vertebrate faunas of the late Middle Miocene (~12 Ma) of Central Europe. Up to now, sixty-two vertebrate taxa, comprising all major groups (fishes, amphibians, reptiles, birds, mammals), have been recorded. Based on sedimentological and palaeobiological evidences, this Fossillagerstätte is assumed to originate from a floodplain paleosol formed on top of a braided river sequence. The fauna points to a highly structured, somewhat vegetated landscape with a wide array of habitats (e.g., fluvial channels, sporadically moist floodplains, short-lived ponds, savannah-like open areas and screes). It was preserved due to a rapid drowning and the switch to a freshwater lake environment. Palaeoclimatological data, derived from pedogenic features as well as from biota, indicate an overall semi-arid, subtropical climate with distinct seasonality (mean annual precipitation 486 ± 252 mm, mean annual temperature ~15°C). This underlines the late Middle/early Late Miocene dry-spell in Central Europe. From taphonomical point of view, the irregularly distributed but roughly associated larger vertebrate remains refer to an in situ accumulation of the bone bed. Splintered bones, gnawing marks as well as rhizoconcretions and root corrosion structures record some pre- and post-burial modification of the taphocoenose. However, the findings of pellet remains argue for a very fast burial and thus to a low degree of time-averaging. For this reason, the fossil fauna reflects the original vertebrate community rather well and is a cornerstone for the understanding of late Middle Miocene terrestrial ecosystems in this region. Certainly, Gratkorn will be one of the key faunas for a high-resolution continental biostratigraphy and the comprehension of Europe’s faunal interchanges near the Middle/Late Miocene transition.     

Reduction of inorganic compounds in autoclaves by using suspended cellulose

Autoclaves are closed vessels in which liquids can be heated above their ‘normal' boiling points. As a consequence the pressure will rise. This equipment has permitted a variety of processes like the syntheses of organics and the leaching of metal ores. Pressure technologies can be used for accelerating reactions, for specific syntheses or they offer an environmental or economical alternative for existing processes. Wet pressure oxidation of sewage sludge, an organic waste product, has become a proven technology. If less oxygen is added than stoichiometrically required for a complete oxidation, cellulose will break down by a different reaction mechanism, releasing electrons. Under these circumstances reduction of inorganic compounds is possible.     

Recruitment of juvenile marine fishes to seagrass habitat in a temperature Australian estuary

We investigated the relationship between distance from the ocean and the recruitment of ocean-spawned juvenile fish to seagrass shallows within marine dominated Lake Macquarie, a coastal barrier lagoon in Southeast Australia. Samples were taken by seine net every 6 wk between June 1986 and June 1987, at 20 sites established at various distances from the entrance channel. The fish fauna was diverse: 80 species from 39 families were caught, with the Gobiidae, Monacanthidae, Syngnathidae, Tetraodontidae, Mugilidae, Atherinidae, Clupeidae, Mullidae, Sparidae, and Blenniidae being well represented. Ambassis jacksoniensis, Atherinomorus ogilbyi, and Gerres subfasciatus accounted for 46% of all individuals. Thirty-two species were classified as ocean spawners, 38 as lagoon spawners, and 10 as unknown in terms of spawning area. Newly settled juveniles of ocean spawners were concentrated near the lagoon's entrance, where most recruited in spring. This pattern occurred in the absence of a salinity gradient: distance from the ocean coupled with weak internal water circulation appears to limit larval distribution and hence juvenile recruitment. Small juveniles of Rhabdosargus sarba were sufficiently abundant for their subsequent dispersal to be directly traced. On the basis of results for this species, and indirect evidence of dispersal for several others, it is suggested that ocean-spawned juveniles, after settling near the entrance, gradually disperse as they grow and change their habitat. Thus, further from the entrance, their recruitment to seagrass shallows is later, at larger sizes, and in smaller numbers. Newly settled juveniles of lagoon spawners, however, were widely distributed within the lagoon. The optimal recruitment of ocean-spawned juveniles to similar coastal lagoons may depend on suitable habitat being available near the entrance. *** DIRECT SUPPORT *** A01BY081 00003