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Research about Puerto Rico

Source-linked reports with geographic coverage including Puerto Rico.

At least 235 records · Page 13Linked to original sources
USGS1999

Puerto Rico, humedales [Puerto Rico, wetlands]

La isla de Puerto Rico, localizada al noreste del Mar Caribe y sus islas principales, Vieques, Culebra e Isla de Mona, poseen humedales en abundancia . El clima subtropical, la lluvia abundante y las complejas formas topográficas y geológicas de estas islas dan origen a los humedales, que varían desde los raros e inusuales bosques cubiertos por nubes en las tierras altas, hasta los extensos manglares, yerbas marinas y arrecifes de coral a lo largo de las costas Norte y Sur. Sin embargo, los humedales en Puerto Rico han disminuido en los últimos siglos como resultado del aumento en el desarrollo agrícola, poblacional y turístico. Algunos tipos de humedales como los bosques de palo de pollo (Pterocarpus officinalis) se han reducido a sólo unos pocos remanentes (figura 1). Biológicamente hablando, los humedales de las islas están entre las áreas más productivas. Los humedales asociados con el bosque pluvial en las tierras altas del interior de Puerto Rico contienen varias plantas raras y especies de animales que no se encuentran en otras partes de la Isla. El agua de escorrentía proveniente de los humedales en las partes altas de la Isla proveen una fuente de agua que utilizan varias ciudades para abasto público. Los humedales costeros como los mangles, los colchones de yerbas marinas y los arrecifes de coral proveen áreas para la reproducción y crianza de varios peces, crustáceos y otras especies en la cadena alimenticia (López y otros, 1988). De esta manera, los humedales costeros contribuyen a la productividad biológica de las aguas llanas del mar alrededor de las islas . Los humedales también estabilizan las costas atrapando y reteniendo sedimentos no consolidados y amortiguan la acción de las olas y de las tormentas que tienen el potencial de causar daños en la zona. El valor de los humedales de Puerto Rico para la vida silvestre está muy bien documentado . Por ejemplo, las salinas de Cabo Rojo, en la costa suroeste, proveen áreas para el descanso y la alimentación de cientos de aves migratorias en ruta entre Norte y Suramérica. Antes del drenaje de los humedales costeros para propósitos agrícolas, pantanos de agua dulce como los de la Laguna Cartagena, Laguna Guánica y Ciénaga El Anegado proveían hábitat a más de 1 00 especies de aves residentes y migratorias . Los humedales de las tierras altas del área central son el último refugio de la cotorra puertorriqueña, una especie en peligro de extinción. Aún los humedales del área metropolitana de San Juan (Laguna La Torrecilla, Torrecilla Baja, Laguna de Piñones hasta Punta Vacía Talega) proveen un hábitat excelente para la vida silvestre, mantienen criaderos de peces de alto valor económico y proveen recreación y oportunidades educativas a la población urbana. Treintiocho especies de vertebrados, moluscos y crustáceos, y 46 especies de aves, algunos raros o en peligro de extinción como la mariquita, el alcatraz, el pato dominicano, el pato silbón y la paloma cabeciblanca han sido observados en el área . También las playas asociadas con estos humedales urbanos proveen sitios de anidaje para las tortugas carey de concha y tinglar, ambas en peligro de extinción (Del Llano y otros, 1986).

Water Supply Paper↗
USGS1998

Chemical weathering in a tropical watershed, Luquillo Mountains, Puerto Rico: II. Rate and mechanism of biotite weathering

Samples of soil, saprolite, bedrock, and porewater from a lower montane wet forest, the Luquillo Experimental Forest (LEF) in Puerto Rico, were studied to investigate the rates and mechanisms of biotite weathering. The soil profile, at the top of a ridge in the Rio Icacos watershed, consists of a 50–100-cm thick layer of unstructured soil above a 600–800 cm thick saprolite developed on quartz diorite. The only minerals present in significant concentration within the soil and saprolite are biotite, quartz, kaolinite, and iron oxides. Biotite is the only primary silicate releasing significant K and Mg to porewaters. Although biotite in samples of the quartz diorite bedrock is extensively chloritized, chlorite is almost entirely absent in the saprolite phyllosilicates. Phyllosilicate grains are present as 200–1000 μm wide books below about 50 cm depth. X-ray diffraction (XRD) and electron microprobe analyses indicate that the phyllosilicate grains contain a core of biotite surrounded by variable amounts of kaolinite. Lattice fringe images under transmission electron microscope (TEM) show single layers of biotite altering to two layers of kaolinite, suggesting dissolution of biotite and precipitation of kaolinite at discrete boundaries. Some single 14-Å layers are also observed in the biotite under TEM. The degree of kaolinitization of individual phyllosilicate grains as observed by TEM decreases with depth in the saprolite. This TEM work is the first such microstructural evidence of epitaxial growth of kaolinite onto biotite during alteration in low-temperature environments. The rate of release of Mg in the profile, calculated as a flux through the soil normalized per watershed land area, is approximately 500 mol hectare −1 yr −1 (1.6 × 10 −9 mol Mg m soil −2 s −1 ). This rate is similar to the flux estimated from Mg discharge out the Rio Icacos (1000 mol hectare −1 yr −1 , or 3.5 × 10 −9 mol Mg m soil −2 s −1 ), indicating that scaling up from the soil to the watershed is possible for Mg release. The rate of Mg release from biotite, normalized to Brunauer-Emmett-Teller (BET) surface area, is calculated using a mass balance equation which includes the density and volume of phyllosilicate grains, porewater chemistry and flux, and soil porosity. The mean rates of biotite weathering calculated from K and Mg release rates are approximately 6 and 11 × 10 −16 mol biotite m biotite −2 s −1 respectively, significantly slower than laboratory rates (10 −12 to 10 −11 mol biotite m biotite −2 s −1 ). The discrepancy in scaling down from the soil to the laboratory is probably explained by (1) differences in weathering mechanism between the two environments, (2) higher solute concentrations in soil porewaters, (3) loss of reactive surface area of biotite in the saprolite due to kaolinite and iron oxide coatings, and/or (4) unaccounted-for heterogeneities in flow path through the soil.

El Yunque, Luquillo Experimental Forest, Luquillo ↗
USGS1998

Geology, geochemistry, geophysics, mineral occurrences, and mineral resource assessment for the Commonwealth of Puerto Rico

The Commonwealth of Puerto Rico has been investigated over a very long period of time by earth scientists from many disciplines and with diverse objectives in the studies. This publication attempts to apply much of the geologic, geochemical, geophysical, and mineral occurrence information to a single objective focused on producing a mineral resource assessment for the Commonwealth of Puerto Rico. However, the value of this publication lies not within the results of the mineral resource assessment nor within the interactive PDF files which can be viewed on the screen, but within the geologic, geochemical, geophysical, and mineral occurrence digital map coverages and databases which can be used for their own unique applications. The mineral resource assessment of Puerto Rico represents compilation of several decades of mineral investigations and studies. These investigations have been the joint efforts of the U.S. Geological Survey, the Puerto Rico Department of Natural Resources, and the University of Puerto Rico. This report contains not only the mineral-resource assessment, but also much of the scientific evidence upon which the assessment was based.

Puerto Rico↗
USGS1997

Hurricane Hortense: impact on surface water in Puerto Rico

Late Monday night, September 9, and into the early morning hours of Tuesday, September 10, 1996, Hurricane Hortense passed over the southwestern part of Puerto Rico (inset). Hurricane Hortense made landfall as a Category One Hurricane (74 to 95 miles per hour) on the Saffir-Simpson Scale, with maximum sustained winds of nearly 80 miles per hour. The eye of Hurricane Hortense moved over the towns of Guayanilla, Yauco, Guánica, Lajas, San Germán, Cabo Rojo, Hormigueros, and Mayagüez (fig. 1).

Fact Sheet↗
USGS1997

Characterization of springflow in the north coast limestone of Puerto Rico using physical, chemical, and stable isotopic methods

The carbonate sequence of middle Tertiary age of the north coast of Puerto Rico is characterized by the presence of numerous springs in the coastal areas. In order to advance the understanding of the hydrologic role of the springs in the north coast limestone aquifer system of Puerto Rico, a 4-year study was conducted by the U.S. Geological Survey in cooperation with the Puerto Rico Aqueduct and Sewer Authority. As part of this study, data were collected on the chemical, physical, bacteriological, oxygen-18, and deuterium composition of water from springs in the Dorado to Rincon area, in northwestern Puerto Rico. A group of springs in the Dorado to Arecibo area was selected for more detailed monitoring. Oxygen-18 and deuterium composition was also determined for water wells and monthly rainfall composites at a series of sites in the study area. Springs are associated with all the carbonate units of the middle Tertiary sequence of the northern karst belt of Puerto Rico, except the Camuy and San Sebastian Formations. These springs mostly drain the unconfined parts of the upper and lower aquifers in the north coast limestone aquifer system. There are no first and second order springs in the north coast limestone and of those present fifth and sixth order springs are the most numerous type. Springflow at the springs measured during the study ranged from less than 0.1 to 61 cubic feet per second. Springs in the north coast limestone can also be classified by their response to rainfall. There is little or no short-term response to rainfall at springs such as Ojo de Agua in Vega Baja, Mameyes in Manati, and Mackovic in Vega Alta. These springs are known as diffuse-type springs. Other springs such as Maguayo in Dorado, Ojo de Guillo in Manati, and San Pedro in Arecibo exhibit a strong short-term response to rainfall and are known as conduit-type springs. Spring water temperature, during the study, ranged from 22.5 to 28 °C and resembled air temperature. Specific conductance ranged from 289 to about 4,000 microsiemens per centimeter, and pH ranged from 6.9 to 7.8. Calcium, sodium, bicarbonate, and chloride are the main ionic species in water from the springs sampled during the study. The main water type is calcium-bicarbonate and secondary water types are calcium-bicarbonate chloride and sodium-bicarbonate-chloride. A seasonal and short-term transient relation exists, particularly in conduit-type springs, between springflow, physical properties, and water quality. Temporal and spatial variations in the oxygen-18 and deuterium composition of modern precipitation are significantly larger than those of springs and ground water in the study area. Regional flow in the upper aquifer appears to attenuate or average the variations in isotopic composition of rainfall. There is, however, a regional gradient in the deuterium composition of water from the upper aquifer in the north coast limestone, with isotopically heavier water occurring further north. It was possible to determine the source of water contributing to springs at some sites with more detailed data collection and analysis. A drainage basin of about 10 square kilometers was delineated for the Ojo de Agua spring in Vega Baja, for a base flow of 2 cubic feet per second and an estimated subregional recharge rate of around 20 inches per year. A delineation of drainage basins for conduit-type springs in the study area such as San Pedro, Ojo de Guillo, Maguayo, and others is very difficult because the boundaries of these systems are highly responsive to changing hydraulic conditions such as rapid and short-term variations in the hydraulic head distribution as a consequence of rainfall. However, a preliminary drainage basin of about 6 square kilometers was delineated for the San Pedro spring for a base flow of 2 cubic feet per second and an estimated subregional annual recharge of 12 inches.

Puerto Rico↗
USGS1996

Low-flow characteristics at selected sites on streams in southern and western Puerto Rico

Knowledge of the magnitude and frequency of low flows is important for the optimal development of surface-water resources in Puerto Rico. This report presents analyses of low-flow data for 9 continuous-record gaging stations and 105 partial-record stations in southern and western Puerto Rico. The report includes analyses of lowflow data and tabulations of computed low-flow magnitude and frequency characteristics for 7-, 14-, 30-, 60-, and 90-consecutive days with recurrence intervals of 2 and 10 years for continuous-record gaging stations based on the log-Pearson Type III frequency distribution or graphically adjusted logPearson frequency curves. Estimates of low-flow characteristics are provided for partial-record stations for 7-, 14-, and 30-consecutive days with recurrence intervals of 2 and 10 years. Low-flow characteristics at partial-record stations were estimated based on the relation of base-flow discharge measurements at the partial-record stations and concurrent discharges at nearby continuous-record stations.

Water-Resources Investigations Report↗
USGS1996

Sedimentation survey of Lago Dos Bocas, Puerto Rico, August 1994

Sedimentation has reduced the storage capacity of Lago Dos Bocas by approximately 43 percent over the last 52 years from 37.5 million cubic meters in 1942 to 21.3 million cubic meters in 1994. If the calculated long term sedimentation rate of 311,000 cubic meters per year remains unchanged, the water-supply storage capacity of the reservoir will be exhausted by the year 2062. Sedimentation in the reservoir has not been uniform. Three tributaries flow into the lake: the Rio Grande de Arecibo, the Rio Caonillas, and the Rio Limon. The Rio Grande de Arecibo has the largest drainage basin and was determined to deliver more sediment to the reservoir than the other two tributaries combined. Only minor amounts of sediment have deposited in the Rio Caonillas branch of the reservoir indicating that Lago Caonillas, located immediately upstream, could be the major sediment repository along the Rio Caonillas tributary. Excluding the Lago Caonillas drainage basin, the long-term sediment yield of the Rio Grande de Arecibo drainage basin is approximately one million kilograms per square kilometer per year.

Lagos Dos Bocas↗