CN - CONFERENCE INFORMATION: Alfred-Wegener workshop on Processes and consequences of deep subduction. Verbania, Italy. Sept. 1999.
LA - LANGUAGE: English
AB - ABSTRACT: We use primarily the generation of acoustic T waves into the ocean by deep seismic sources to investigate the propagation of high-frequency seismic energy from the bottom of subduction zones to the shoreline at the earth"s surface. Conversion from shear waves to oceanic acoustic waves can be used as a proxy for the existence of a continuous slab featuring low anelastic attenuation. With the help of other techniques, such as the estimation of Q from S-to-P spectral amplitude ratios, we examine systematically a number of regions where earthquakes have been described as "detached". We establish the mechanical continuity of the slab to the hypocenters of the 1990 Sakhalin and 1982 Bonin events, which occurred several hundred kilometers in front of the mainstream seismic zone. The study of the 1989 Paraguay shock is inconclusive, probably due to its much smaller size. The vertical continuity of the South American slab through its aseismic depth range is verified, and a similar situation probably exists in Java. Attenuation data suggests that the deep Spanish earthquakes occur within a vertically large segment of colder material, and a similar situation may exist in Colombia. The only clearly detached deep events with no mechanical connection to the surface make up the Vityaz cluster, under the North Fiji Basin. Based on a variety of geophysical evidence, the small deep earthquakes under New Zealand are likely to take place in a detached blob at least 350km below the termination of mainstream seismicity. These results support a model integrating buoyancy forces over a long continuous slab as the source of the down-dip compressional stresses observed in large earthquakes at the bottom of the transition zone.
MC - MAP COORDINATES: LAT: N011300; N011300; LONG: W0772200; W0772200.
LAT: N413600; N413600; LONG: E0014800; E0014800.
LAT: N115900; N115900; LONG: W0860300; W0860300.
LAT: N374100; N374600; LONG: W1184300; W1185200.
IL - ILLUSTRATION: Refs: 3
RF - REFERENCE SOURCE: GeoRef, Copyright 2002, American Geological Institute.
IS - ISSN: 0701-8738
CO - CODEN: PAACD6
AN - ACCESSION NUMBER: 2002-013416
UD - UPDATE CODE: 200206
Registro 629 de 5614 - GeoRef : 2002-2004/12
TI - TITLE: Behaviour of the fecal pollution indicators in a soil irrigated with treated wastewater under onsurface and subsurface dip irrigation.
AU - AUTHORS: Campos-C; Oron-G; Saigot-M; Gillerman-L
AF - AUTHOR AFFILIATION: Universidad Javeriana, Departamento de Microbiologia, Bogota, Colombia
BK - BOOK TITLE: In: Environmental challenges for the next millenium; selected proceedings of the 7th international conference of the Israel Society for Ecology and Environmental Quality Sciences.
BA - BOOK AUTHORS: Adin-A (editor); Belkin-S (editor)
SO - SOURCE: Water Science and Technology. 42; 1-2, Pages 75-79. 2000.
PB - PUBLISHER: Pergamon. Oxford-New York, International. 2000.
CP - COUNTRY OF PUBLICATION: International
PY - PUBLICATION YEAR: 2000
CN - CONFERENCE INFORMATION: 7th international conference of the Israel Society for Ecology and Environmental Quality Sciences. Jerusalem, Israel. June 13-18, 1999.
LA - LANGUAGE: English
AB - ABSTRACT: A critical objective for any wastewater reuse programme is to minimise health and environmental hazard. When applying wastewater to soil-plant systems, it is to be noted that the passage of water through the soil considerably reduces the number of microorganisms carried by the reclaimed wastewater. Factors that affect survival include number and type of microorganisms, soil organic matter content, temperature, moisture, pH, rainfall, sunlight, protection provided by foliage and antagonism by soil microflora. The purpose of this work was to examine the behaviour of fecal pollution indicators in a soil irrigated with treated wastewater under onsurface and subsurface drip irrigation. The experiment was conducted in a vineyard located at a commercial farm near the City of Arad (Israel). Wastewater and soil samples were monitored during the irrigation period and examined for fecal coliforms, somatic and F+ coliphages and helminth eggs. Physico-chemical parameters were controlled in order to determine their relationship with removal of microorganisms. The results showed high reduction of the concentration of microorganisms when wastewater moves through the soil; and a good correlation between the reduction of fecal pollution indicators and moisture content, organic matter concentration and pH. The application of secondary treated domestic wastewater in this specific soil and under these irrigation systems affect the survival of microorganisms, thus reducing the health and environmental risk.
AB - ABSTRACT: The rocks in the southern Oaxacan Complex of Mexico form part of the basement of Oaxaquia, a terrane that underlies most of eastern Mexico. They have undergone granulite facies metamorphism at approximately 1 Ga, that was initially overprinted by lower amphibolite facies metamorphism accompanied by extensive hydration, and then by greenschist facies metamorphism. Geochemical data indicate that protoliths include volcanic arc lavas and sediments intruded by a rift-related granite. The metavolcanic rocks have SiO (sub 2) ranging between 55 and 72%, are typically enriched in highly incompatible elements such as Ba, Rb and light rare earth elements, and are accompanied by relative depletion of Nb and Ti characteristic of subduction-related magmas. The granite has SiO (sub 2) ranging between 67 and 70%, is enriched in strongly incompatible elements, and depleted in Nb and Ti indicative of either a crustal source or a subduction-related tectonic setting. Concordant, U-Pb analyses of single zircons from this granite yield an age of 1117+ or -4 and 988+ or -5 Ma interpreted as the age of intrusion and the time of peak granulite facies metamorphism, respectively. Combined with published information from other parts of Mexico, these data indicate that Oaxaquia was a juvenile arc metamorphosed during a relatively young Grenvillian metamorphism at 990 Ma. Similar characteristics may also be found in the Andean massifs of Colombia and in the Appalachian terranes (Carolina-Piedmont and Avalon) of Amazonian provenance. This suggests that Oaxaquia may also have lain adjacent to northwestern Amazonia at approximately 1 Ga, a location that may allow Neoproterozoic subduction as the origin of the hydrous, lower amphibolite facies metamorphism. It would also provide a proximal source for low grade to unmetamorphosed approximately 1 Ga and Neoproterozoic igneous boulders in northern Oaxaquia and 1000-900 Ma detrital zircons in Neoproterozoic and Paleozoic sedimentary rocks in Avalonia and Iberia.