Freshwater Regimes Research Articles

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.

Effects of crude oil ingestion on avian intestinal function.

Intestinal function in mallard ducklings (Anas platyrhynchos) on a freshwater regime was studied after a 7-day dietary ingestion of 0.25% and 2.5% Prudhoe Bay crude oil (PBCO) or a 2.5% paraffin mixture with an in vivo luminal perfusion technique. Dietary ingestion of 2.5% PBCO may have an effect on the integrity of the duckling intestine. There were no significant effects of PBCO on the absorption of Na, Cl, K, or H2O compared with control animals. The ducklings fed 2.5% paraffin had a significant depression in Na and H2O absorption compared with controls. However, this depression dose not seem to be related to an effect on intestinal mucosa Na-K-ATPase activity.

The freshwater regime of Faxaflói, Southwest Iceland, and its relationship to meteorological variables

On the basis of 15 surveys of 23 hydrographic stations in Faxaflói, Southwest Iceland, and the adjacent shelf region in the period February 1966 to March 1967 the freshwater regime of the bay is studied in relation to meteorological and hydrological factors. The freshwater content inside the bay ranged between 1950 × 10 6 and 5350 × 10 6m 3 with an average value of 3164 × 10 6m 3. Direct runoff into Faxaflói averaged 29.28 × 10 6m 3 per day. However, the freshwater distribution, presented by means of charts of equivalent fresh-water thicknesses, suggests that the freshwater input is not only due to local runoff and surplus precipitation, but also to advection of low-salinity water by the coastal current from the nearshore area south of Iceland. Analysis of wind data indicates a close association between the rate of change of the freshwater volume inside the bay between observations and the mean southerly wind component for the same period. This relationship is explained as the result of (a) southerly winds enhancing the transport of freshwater into the bay from the region south of Reykjanes and (b) wind-driven transport leading to accumulation of freshwater in the bay. Conversely, winds from the north are believed to favour the transport of fresh surface water out of the bay and suppress the inflow of freshwater by the coastal current from the south. Statistical methods were applied to the quantitative analysis of factors effecting changes in the freshwater content of Faxaflói. The results strongly support the view that winds in the N-S direction are a major factor in producing the observed variations in freshwater content.