Changing patterns of Pennsylvanian coal-swamp vegetation and implications of climatic control on coal occurrence

Improved regional and interregional stratigraphic correlations of Pennsylvanian strata permit comparisons of vegetational changes in Euramerican coal swamps. The coal-swamp vegetation is known directly from in situ coal-ball peat deposits from more than 65 coals in the United States and Europe. Interpretations of coal-swamp floras on the basis of coal-ball peat studies are extended to broader regional and stratigraphic patterns by use of coal palynology. Objectives of the quantitative analyses of the vegetation in relation to coal are to determine the botanical constituents at the peat stage and their environmental implications for plant growth and peat accumulation. Morphological and paleoecological analyses provide a basis for deducing freshwater regimes of coal swamps.Changes in composition of Pennsylvanian coal-swamp vegetation are quire similar from one paralic coal region to another and show synchrony that is attributable to climate. Paleobotany and paleogeography of the Euramerican province indicate a moist tropical paleoclimate. Rainfall, runoff and evapotranspiration were the variable climatic controls in the distribution of coal-swamp vegetation, peat accumulation and coal resources. In relative terms of climatic wetness the Pennsylvanian Period is divisible into five intervals, which include two relatively drier intervals that developed during the Lower-Middle and Middle-Upper Pennsylvanian transitions. The climate during Early Pennsylvanian time was moderately wet and the median in moisture availability. Early Middle Pennsylvanian was drier, probably seasonally dry-wet; late Middle Pennsylvanian was the wettest in the Midcontinent; early Late Pennsylvanian was the driest; and late Late Pennsylvanian was probably the wettest in the Dunkard Basin. The five climatic intervals represent a general means of dividing coal resources within each region into groups with similar botanical constituents and environments of peat accumulation. Regional differences in basinal geology and climate were significant variables, but the synchronous control of paleoclimate was of primary importance.     

Simultaneous exposure of English sole (Parophrys vetulus) to sediment-associated xenobiotics: Part 1—uptake and disposition of 14C-polychlorinated biphenyls and 3H-benzo[a]pyrene

English sole (Parophrys vetulus) were exposed to environmentally realistic levels of sediment-associated ³H-benzo[a]pyrene (3 μg BaP/g sediment, dry weight) and ¹⁴C-Aroclor 1254 (1 μg PCBs/g), separately and together, for up to 10 days. BaP and its metabolites in tissues reached steady-state concentrations by the first day of the exposure, whereas PCBs did not approach steady-state concentrations until the tenth day of exposure. Simultaneous exposure of sole to BaP and PCBs, relative to separate exposure to the xenobiotics, significantly increased the concentrations of BaP-derived radioactivity and decreased the concentrations of PCB-derived radioactivity in some tissues and bile. Accumulation of PCB-derived radioactivity, estimated as the burden in tissues, was significantly greater (4- to 13-fold) than that of BaP-derived radioactivity throughout the experiments and regardless of the type of exposure. The rank of the concentrations of PCB-derived radioactivity in tissues and bile was: bile ～ liver > brain > kidney ～ gill > skin ～ blood ～ muscle and for BaP-derived radioactivity the order was: bile > liver > gill > kidney > skin ～ blood > muscle > brain. BaP-derived radioactivity in liver and bile was present primary (85–99%) as metabolites, whereas PCB-derived radioactivity was present equally as parent compounds and metabolites in bile and primarily (98 %) as parent compounds in liver. Hydrolysis of bile from PCB/BaP-exposed sole with β-glucuronidase/arylsulfatase released 35 % of the BaP-derived radioactivity and 32 % of the PCB-derived radioactivity as primary metabolites. A much higher proportion of the BaP-derived radioactivity (64 %) than the PCB-derived radioactivity (13 %) in bile was unaffected by the enzyme treatment, indicating differences in the conjugation of the primary metabolites of PCBs and BaP. The results suggest that in contaminated environments the tissue to sediment concentration ratios for PCBs would exceed that for BaP and its metabolites; however, BaP would be continually absorbed and metabolized by sole to potentially carcinogenic and mutagenic compounds. In addition, the tissue levels of these toxic compounds may be increased by simultaneous exposure to PCBs.     

Breaking wave loads at vertical seawalls and breakwaters

This paper presents recent advances in knowledge on wave loads, based on experimental work carried out in the CIEM/LIM large flume at Barcelona within the framework of the VOWS (Violent Overtopping by Waves at Seawalls) project. Both quasi-static and impact wave forces from the new data set have been compared with predictions by empirical and analytical methods. The scatter in impact forces has been found to be large over the whole range of measurements, with no existing method giving especially good predictions. Based on general considerations, a simple and intuitive set of prediction formulae has been introduced for quasi-static and impact forces, and overturning moments, giving good agreement with the new measurements. New prediction formulae have been compared with previous measurements from physical model tests at small and large scale, giving satisfactory results over a relatively wide range of test conditions. The time variation of wave impacts is discussed, together with pressure distribution up the wall, which shows that within experimental limitations the measured pressures are within existing limits of previous study.     

A Method for Installing Piezometers in Large Cobble Bed Rivers

An impact drive point method is described for emplacing piezometers in a cobble river bottom where this has previously been difficult without the use of drilling rigs. To force the drive point piezometers through coble, the vibrational impact of an air-powered hammer was carried directly to the drive point by the use of an internal drive rod. After insertion to depth, the drive rod was removed from the lower portion of the piezometer and a standpipe was added to extend the piezometer above the river level. Piezometers installed in this way have permitted water quality analysis and dynamic measurement of vertical potentials in cobble sediments ranging in size from 2.5 to >30 cm and the method has been successfully used in the Columbia River, USA, and Töss River, Switzerland. This innovative method provides information on the hydrodynamics of pore water in highly permeable, cobble deposits that are common in high-energy river and lake bottoms. Piezometers installed using the internal drive rod method facilitate the assessment of the temporal and spatial dynamics of recharge and discharge at the ground water/surface water interface and analyses of the ecological connectivity between the hyporheic zone and surface water of rivers and streams. This information will lead to improved management decisions related to our nation's ground water and surface water supplies.