The Fill–Spill Hydrology of Prairie Wetland Complexes during Drought and Deluge

The fill–spill of surface depressions (wetlands) results in intermittent surface water connectivity between wetlands in the prairie wetland region of North America. Dynamic connectivity between wetlands results in dynamic contributing areas for runoff. However, the effect of fill–spill and the resultant variable or dynamic basin contributing area has largely been disregarded in the hydrological community. Long‐term field observations recorded at the St. Denis National Wildlife Area, Saskatchewan, allow fill–spill in the basin to be identified and quantified. Along with historical water‐level observations dating back to 1968, recent data collected for the basin include snow surveys, surface water survey and production of a light detection and ranging–derived digital elevation model. Data collection for the basin includes both wet and dry antecedent basin conditions during spring runoff events. A surface water survey at St. Denis in 2006 reveals a disconnected channel network during the spring freshet runoff event. Rather than 100% of the basin contributing runoff to the outlet, which most hydrological models assume, only approximately 39% of the basin contributes to the outlet. Anthropogenic features, such as culverts and roads, were found to influence the extent and spatial distribution of contributing areas in the basin. Historical pond depth records illustrate the effect of antecedent basin conditions on fill–spill and basin contributing area. A large pond at the outlet of the St. Denis basin, which only receives local runoff during dry years when upstream surface storage has not been satisfied, has pond runoff volumes that increase by a factor of 20 or more during wet years when upstream antecedent basin surface storage is satisfied and basin‐wide runoff contributes to the pond. Copyright © 2011 John Wiley & Sons, Ltd.     

Oxygen and hydrogen isotope compositions as indicators of granite genesis in the New England Batholith,Australia

Oxygen and hydrogen isotope studies of a number of granite suites and mineral separates from the New England Batholith indicate that O¹⁸ can be used to discriminate the major granite protoliths. The granite suites previously subdivided on the basis of mineralogical and geochemical criteria into S-type (sedimentary) and I-type (igneous) have O¹⁸ values consistently higher in the S-type granites (10.4–12.5) than in the spatially related I-type plutons (7.7–9.9). There appears to be a systematic variation in O¹⁸ from the most S-type to the most I-type granites, the dividing point between the two occuring at O¹⁸ equal to 10. A group of leucocratic granites that form about half of the batholith and difficult to classify mineralogically and geochemically is found to have low O¹⁸ values (6.4–8.1), suggesting an affinity to the most I-type granites. A single leucogranite pluton with minor muscovite has a O¹⁸ of 9.6 which is significantly higher than other leucogranites indicating a different origin perhaps involving amphibole fractionation.The behavior of D in the plutonic rocks is much less systematic than O¹⁸. Excluding samples collected adjacent to major faults, the D values show a rough positive correlation with water content similar to, but less pronounced than, the trend previously observed in the Berridale Batholith, southeastern Australia. This relation is considered to reflect an interaction between meteoric water and the granites, the largest effect being observed in samples with the least amount of water. Of note is the generally lower D values of the upper Paleozoic New England Batholith compared with the Silurian Berridale Batholith. This difference may be related to a near equatorial paleolatitude of 22 °S in the Silurian and near polar paleolatitudes in the late Carboniferous that have been inferred for these regions. Granite samples collected from near major faults, and one ignimbrite sample of rhyodacite composition, have very low D values (less than –120) suggesting a much greater degree of interaction with meteoric water.     

The impact of oestrogenic and androgenic contamination on marine organisms in the United Kingdom--summary of the EDMAR programme. Endocrine Disruption in the Marine Environment

This paper summarises results of the EDMAR programme which is investigating oestrogenic and androgenic endocrine disruption in UK coastal waters. Most of the data concern fish. Four species (flounder, viviparous blenny and two sand gobies) are experiencing feminisation in industrialised estuaries. In males this includes vitellogenin (VTG) synthesis, ovotestis induction and/or feminised sexual characteristics. Although reproductive success may be impaired in some cases, implications for fish populations are still unclear. Suspected causative contaminants include natural oestrogenic substances and synthetic oestrogen mimics. The majority of the oestrogenic activity is adsorbed to sediments, and routes of exposure may include benthic food chain transfer. Some natural androgenic substances are also being discharged to estuaries, but their activity appears low.     

Plume dynamics, thermal energy and long-distance transport of vulcanian eruption clouds from Augustine Volcano, Alaska

Augustine, an island volcano in Lower Cook Inlet, southern Alaska, erupted in January, 1976, after 12 years of dormancy. By April, when the eruptions ended, a new lava dome had been extruded into the summit crater and about 0.1 km³ of pyroclastics had been deposited on the island, mainly as pyroclastic debris avalanches and pumice flows. The ventclearing phase in January was highly explosive and we have been able to document 13 major vulcanian eruptions.The timing, thermal energy, mass loading of fine particles and the horizontal dispersion of these eruption clouds were determined from radar measurements of cloud height, reports of pilots flying in plumes, satellite photography, seismic records and infrasonic detection of air waves. A lower estimate of the mass of fine (r < 68 μm) particles injected into the troposphere from the 13 main eruptions in January is 5.5–18 × 10¹² g. The corresponding mass loading of fine particles within individual eruption clouds is 0.3–1 g m⁻³. We calculated thermal energies of 4 × 10¹⁴ to 35 × 10¹⁴ J for individual eruptions by applying convective plume rise theory to observed cloud heights and seismically determined eruption durations. This energy range compares favorably with the 4–16 × 10¹⁴ J of thermal energy, calculated from the cooling of juvenile material contained in a typical eruption cloud.The vulcanian eruption clouds stayed intact for at least 700 km downwind. Satellite images in both visible and infrared wavebands, showing the Gulf of Alaska just after sunrise on January 23, reveal a series of puffs strung out downwind from the volcano, 20–30 km in diameter and with their tops at altitudes of about 8 km, overlying a continuous plume at altitude 4 km. Each puff corresponded to a seismically and infrasonically timed eruption. A substantial portion of the material injected into the atmosphere between January 22 and 25 was rapidly transported by the subpolar jet stream through southwestern Canada and the western United States, then northeast across the States into the Atlantic. The clouds were observed passing over Tucson, Arizona, on January 25 at an elevation of 7 km.Several of the eruptions penetrated into the stratosphere. Sun photometer measurements, taken at Mauna Loa, Hawaii, six weeks after the eruption, showed an increased stratospheric optical thickness of 0.01 (wavelength 0.5 μm), which decayed in about 5 months. The maximum column mass loading of the veil was 4–10 × 10⁻⁷ g cm⁻². The mass of the veil, spread-ever a fourth of the earth's surface, is 10 to 100 times larger than can be accounted for by assuming that injected ash and converted sulfate particles from the 13 main Augustine eruptions are the only components contributing to the stratospheric turbidity observed at Mauna Loa.     

An application of factor analysis to basic volcanic rock geochemistry

Factors analysis is useful for studying the interrelationships of trace and major elements in sets of rock analyses. Its application to basic volcanic rocks show various features: (i) the principal factors relate to variation among mineral components; (ii) the behaviour of K is similar to that of Rb, Ba, Sr and in some cases P, W, Tl also; (iii) the coherence of Tl with K and Rb is often masked by a secondary effect depending on petrography; (iv) in some rock-groupings Li and H₂O^? are closely associated; (v) an unexpected association is Na, P and Sr; (vi) factor-scores can be used to discriminate alkalic from subalkalic basalts, using various element combinations.     

Duricrust development and valley evolution: Process–landform links in the kalahari

Duricrusts are an important landscape component of the Kalahari region of central southern Africa. Their exposures within the dry valleys (mekgacha) of the Kalahari provide some of the most widespread surface outcrops of the terrestrial Jurassic to Holocene Kalahari Group sediments. Exposures have been extensively used in the construction of lithostrati-graphic sequences, on the assumption that valley systems have incised their courses through a pre-existing duricrust sequence. Recent work, however, has identified the role of groundwater erosion processes in valley development, which may have influenced duricrust formation. Studies of duricrusts from boreholes drilled within two mekgacha show that duricrust type is intrinsically related to the presence of a valley. Analyses of calcretes and silcretes in a series of profiles and thin sections from the Letlhakeng area of Botswana also indicate extensive alteration and diagenesis in association with former higher water tables. Sedimentary sequences within duricrust host materials can be identified but there is no evidence for correlation of duricrust cements between exposures. Profile studies from the Auob Valley in Namibia, however, suggest that this valley has incised through a sequence of duricrusts. Caution is advised in future attempts to correlate duricrust types on the basis of valley exposures, with the recommendation that where such exposures are used in a lithostratigraphic context, only duricrust host material characteristics and not cementing materials should be considered.     

The Silent Lake Pluton,Ontario: a nodular,sedimentary, intrusive complex

The Precambrian Silent Lake pluton, Cardiff township, Ontario, consists of granitic rocks containing, in many localities, abundant quartz-sillimanite nodules.The intrusive form of the Pluton and massive character of most rocks suggests a magmatic origin. Lack of (a) sharp contacts, (b) apophyses, (c) contact metamorphism, (d) evidence of systematic magma evolution in the haplogranite system, (e) country-rock xenoliths, suggest non-magmatic origin. Polyhedral textures indicate annealing after emplacement. Bulk chemical composition, including very low Ca, low Mg, low Sr, high Sr/Ca indicate sedimentary (arkosic) origin. The rocks appear to be Hermon formation leptites mobilized and emplaced by ductile flow, followed by annealing.Structural, mineralogical, chemical and oxygen isotopic evidence indicate the nodules to have formed by deformation and de-alkalization of quartz-feldspar veins within the mobilized leptites.