Ecological response to hurricane events in the Pamlico Sound system, North Carolina, and implications for assessment and management in a regime of increased frequency   总被引：1，自引：0，他引：1  

Hans W. Paerl  Lexia M. Valdes  Alan R. Joyner  Benjamin L. Peierls  Michael F. Piehler  Stanley R. Riggs  Robert R. Christian  Lisa A. Eby  Larry B. Crowder  Joseph S. Ramus  Erika J. Clesceri  Christopher P. Buzzelli  Richard A. Luettich 《Estuaries and Coasts》2006,29(6):1033-1045

Since the mid 1990s, the Atlantic and Gulf Coast regions have experienced a dramatic increase in the number of hurricane landfalls. In eastern North Carolina alone, eight hurricances have affected the coast in the past 9 years. These storms have exhibited individualistic hydrologic, nutrient, and sediment loading effects and represent a formidable challenge to nutrient management aimed at reducing eutrophication in the Pamlico Sound and its estuarine tributaries. Different rainfall amounts among hurricanes lead to variable freshwater and nutrient discharge and variable nutrient, organic matter, and sediment enrichment. These enrichments differentially affected physical and chemical properties (salinity, water residence time, transparency, stratification, dissolved oxygen), phytoplankton primary production, and phytoplankton community composition. Contrasting ecological responses were accompanied, by changes in nutrient and oxygen cycling, habitat, and higher trophic levels, including different direct effects on fish populations. Floodwaters from the two largest hurricances, Fran (1996) and Floyd (1999), exerted, multi-month to multi-annual effects on hydrology, nutrient loads, productivity, and biotic composition. Relatively low rainfall coastal hurricanes like Isabel (2003) and Ophelia (2005) caused strong vertical mixing and storm surges, but relatively minor hydrologic and nutrient effects. Both hydrologic loading and wind forcing are important drivers and must be integrated with nutrient loading in assessing short-term and long-term ecological effects of these storms. These climatic forcings cannot be managed but should be considered in the development of water quality management strategies for these and other large estuarine ecosystems faced with increasing frequencies and intensities of hurricane activity.  相似文献   

Strontium isotope and alkali element geochemistry of selected sediments from the northeast Pacific Ocean     

Stanley E Church 《Geochimica et cosmochimica acta》1971

  相似文献   

Introduction of Jean-François Minster for the F. W. Clarke Medal 1981     

Stanley R. Hart 《Geochimica et cosmochimica acta》1982,46(6):1135-1136

  相似文献   

Controlled source electrical methods for deep exploration     

Stanley H. Ward 《Surveys in Geophysics》1983,6(1-2):137-152

Application of controlled source electrical methods (CSEM) is impeded by natural field, electrification, geological, cultural, and topographic noise. Lateral resolution of parameters of adjacent steeply dipping bodies and vertical resolution of parameters of adjacent beds in a flatly dipping sequence are concerns with any CSEM method. Current channeling into a localized good conductor from a surrounding, overlying, or underlying conductor poses problems for the interpreter. A summary of the results of several recent experiments with CSEM techniques illustrates that with care and difficulty they can be used to depths on the order of 20 km. If measurements are made on a relatively uniform resistive surface, as can be found in glaciated Precambrian terranes, then either a grounded bipole or a loop source is acceptable. Most of the recent CSEM experiments were made over resistive Precambrian rocks and all were directed toward detecting a conductive layer near 20 km depth. For exploration beyond this depth, however, the MT/AMT method would seem to be preferred. The rationale behind this conclusion is largely contained in consideration of the ratio of signal to natural field noise. Where thick irregular surficial overburden of low resistivity occurs, two- and three-dimensional modeling is necessary to stripp off the effects of the shallow layers. This may not be possible for CSEM and then MT/AMT becomes the only alternative.  相似文献   

Helium isotopic variations in volcanic rocks from Loihi Seamount and the Island of Hawaii     

Mark D. Kurz  William J. Jenkins  Stanley R. Hart  David Clague 《Earth and Planetary Science Letters》1983

Helium isotopic ratios ranging from 20 to 32 times the atmospheric ³He/⁴He(R_A) have been observed in a suite of 15 basaltic glasses from the Loihi Seamount. These ratios, which are up to four times higher than those of MORB glasses and more than twice those of nearby Kilauea, are strongly suggestive of a primitive source of volatiles supplying this volcanism. The Loihi glasses measured span a broad compositional range, and the ³He/⁴He ratios were found to be generally lower for the alkali basalts than for the tholeiites. The component with a lower ³He/⁴He ratio appears to be associated with olivine xenocrysts, within which fluid inclusions are probably the carrier of contaminant helium. One Loihi sample has a much lower isotopic ratio (<5 R_A), but a combination of low He concentration, high vesicularity, and presence of cracks lined with clay minerals suggests that the low ratio is due to gas loss and contamination by atmospheric helium.Crushing and melting experiments show that for modest vesicularities (<5% by volume) the Loihi glasses obey a MORB-type partitioning trend, but at higher vesicularities the data show considerably more scatter due to volatile mobilization. The high vesicularities, low extrusion pressure and generally low helium concentrations are consistent with a considerable degree of degassing. Analyses of dunites, plus a correlation between total helium concentrations with xenocryst abundances also suggest that xenocrysts are a significant carrier of contaminating (low ³He/⁴He) helium.³He/⁴He ratios from samples of other Hawaiian volcanoes (Kilauea, Mauna Loa, Hualalai, and Mauna Kea) show a smooth decrease in ³He/⁴He with increasing volcano age and volume. We interpret this to be a synoptic picture of the time evolution of a hot-spot diapir: the earliest stage is characterized by primitive (> 30 R_A) helium with some (variable) component of lithospheric contamination added during “breakthrough”, while the later stages are characterized by a relaxation toward lithospheric ³He/⁴He ratios (～ 8 R_A) due to isolation of the diapir from the mantle below (as the plate moves on), and subsequent mining of the inherited helium and contamination from the surrounding lithosphere. The abrupt contrast in ³He/⁴He ratios between Kilauea and Loihi, despite their close proximity, is indicative of the small lateral extent of the plume.  相似文献   

Diel activity cycles of two Chesapeake Bay fishes,the striped blenny (Chasmodes bosquianus) and the oyster toadfish (Opsanus tau)     

Robert R. Phillips  Stanley B. Swears 《Estuaries and Coasts》1981,4(4):357-362

Diel activity cycles of toadfish and striped blennies were identified in the laboratory by means of mechanoelectric detector units. Data for both species were collected over 72-h periods. Daytime and nighttime activity rates were compared statistically. In addition, five 3-h segments (3 during the day and 2 at night) were selected for statistical comparison. both species are more active at night than during the day. The toadfish appears to be more strictly nocturnal than does the blenny, with the peak in its activity occurring in the 3-h segment following dusk. Blenny activity increases throughout the night, reaching a peak during the 3-h segment before dawn. It then ebbs to a low in the afternoon.  相似文献   

Pompeii Damaged by Volcaniclastic Debris Flows Triggered Centuries Prior to the 79 A.D. Vesuvius Eruption     

Maria Rosaria Senatore  Annamaria Ciarallo  Jean‐Daniel Stanley 《Geoarchaeology》2014,29(1):1-15

This study records that Pompeii, long before its final devastation by the 79 A.D. Vesuvius eruption in southern Italy, was damaged by several mass gravity flows. Composition of the deposits indicates that they were derived from volcaniclastic cover of carbonate highlands positioned 14 km NE of the city. Stratigraphic and petrologic analyses of sections in excavations and drill cores in and near Pompeii record the presence of three downslope‐directed debris flows dated between 8th and 2nd century B.C. Some of these deposits were channelized via a stream bed that once extended from high reliefs to Pompeii. It is proposed that one of these events may have been partially responsible for urban decline during the 4th century B.C. These mass flows are interpreted as having been triggered primarily by intense rains in a manner similar to those that have occurred and destroyed towns in this region during the past 50 years. Our investigation shows that Pompeii and adjacent areas in the past, much as in recent time, have likely been most frequently susceptible to episodic damage by avalanches and mass flows of volcaniclastic material resulting from hydrological effects rather than from volcanic events, earthquake tremors, and societal disruptions such as wars.  相似文献