The permeability of the Elkhorn fault zone,South Park,Colorado

The purposes of this study are to use both field and modeling approaches to characterize the permeability of a fault and to assess the role of the fault on regional ground water flow. The study subject is the Elkhorn fault, a low-angle reverse fault that brings Precambrian crystalline rocks over the sediments of Colorado's South Park Basin. The fault is hypothesized to act as a low-permeability barrier to flow, restricting interaction between the crystalline aquifer and the basin sediments. To test this hypothesis and to better predict the permeability structure of the fault, we synthesized geologic data to create a geologic model of the fault, conducted aquifer tests to estimate the hydrogeologic properties of the fault zone, and used ground water modeling to test the influence of a range of hydraulic properties for the fault zone on ground water flow in the region. Our study suggests that the fault is a low-permeability feature. Estimated heads are best matched to observations by modeling the fault as a 10-foot-thick interval of low-permeability fault gouge. Steady-state flow models show that much of the flow in the study area is topographically driven near land surface. Flow rates decrease with depth in the aquifers. In the footwall, ground water moves updip in the Michigan-San Isabel syncline to discharge in the South Park Basin. In the hanging wall, ground water moves east to a regional ground water divide. Sensitivity analyses indicate that hydraulic heads are most sensitive to changes in hydraulic conductivity and recharge.     

Meso-scale testing and development of test procedures to maintain mass balance

The Conrad Blucher Institute for Surveying and Science (Texas A&M University––Corpus Christi) has conducted numerous petroleum experiments at the Shoreline Environmental Research Facility (Corpus Christi, Texas, USA). The meso-scale facility has multiple wave tanks, permitting some control in experimental design of the investigations, but allowing for real-world conditions. This paper outlines the evolution of a materials balance approach in conducting petroleum experiments at the facility. The first attempt at a materials balance was during a 1998 study on the fate/effects of dispersant use on crude oil. Both water column and beach sediment samples were collected. For the materials balance, the defined environmental compartments for oil accumulation were sediments, water column, and the water surface, while the discharge from the tanks was presumed to be the primary sink. The “lessons learned” included a need to quantify oil adhesion to the tank surfaces. This was resolved by adhering strips of the polymer tank lining to the tank sides that could be later removed and extracted for oil. Also, a protocol was needed to quantify any floating oil on the water surface. A water surface (oil slick) quantification protocol was developed, involving the use of solid-phase extraction disks. This protocol was first tested during a shoreline cleaner experiment, and later refined in subsequent dispersant effectiveness studies. The effectiveness tests were designed to simulate shallow embayments which created the need for additional adjustments in the tanks. Since dispersant efficacy is largely affected by hydrodynamics, it was necessary to scale the hydrodynamic conditions of the tanks to those expected in our prototype system (Corpus Christi Bay, Texas). The use of a scaled model permits the experiment to be reproduced and/or evaluated under different conditions. To minimize wave reflection in the tank, a parabolic wave dissipater was built. In terms of materials balance, this design reduced available surface area as a sink for oil adsorption.     

Regional estimation of base recharge to ground water using water balance and a base-flow index

Naturally occurring long-term mean annual base recharge to ground water in Nebraska was estimated with the help of a water-balance approach and an objective automated technique for base-flow separation involving minimal parameter-optimization requirements. Base recharge is equal to total recharge minus the amount of evapotranspiration coming directly from ground water. The estimation of evapotranspiration in the water-balance equation avoids the need to specify a contributing drainage area for ground water, which in certain cases may be considerably different from the drainage area for surface runoff. Evapotranspiration was calculated by the WREVAP model at the Solar and Meteorological Surface Observation Network (SAMSON) sites. Long-term mean annual base recharge was derived by determining the product of estimated long-term mean annual runoff (the difference between precipitation and evapotranspiration) and the base-flow index (BFI). The BFI was calculated from discharge data obtained from the U.S. Geological Survey's gauging stations in Nebraska. Mapping was achieved by using geographic information systems (GIS) and geostatistics. This approach is best suited for regional-scale applications. It does not require complex hydrogeologic modeling nor detailed knowledge of soil characteristics, vegetation cover, or land-use practices. Long-term mean annual base recharge rates in excess of 110 mm/year resulted in the extreme eastern part of Nebraska. The western portion of the state expressed rates of only 15 to 20 mm annually, while the Sandhills region of north-central Nebraska was estimated to receive twice as much base recharge (40 to 50 mm/year) as areas south of it.     

A description of how metal pollution occurs in the Tinto-Odiel rias (Huelva-Spain) through the application of cluster analysis

In the last few decades, the study of space-time distribution and variations of heavy metals in estuaries has been extensively studied as an environmental indicator. In the case described here, the combination of acid water from mines, industrial effluents and sea water plays a determining role in the evolutionary process of the chemical makeup of the water in the estuary of the Tinto and Odiel Rivers, located in the southwest of the Iberian Peninsula.Based on the statistical treatment of the data from the analysis of the water samples from this system, which has been affected by processes of industrial and mining pollution, the 16 variables analyzed can be grouped into two large families. Each family presents high, positive Pearson r values that suggest common origins (fluvial or sea) for the pollutants present in the water analyzed and allow their subsequent contrast through cluster analysis.     

Comparison of heat and bromide as ground water tracers near streams

Heat and bromide were compared as tracers for examining stream/ground water exchanges along the middle reaches of the Santa Clara River, California, during a 10-hour surface water sodium bromide injection test. Three cross sections that comprise six shallow (<1 m) piezometers were installed at the upper, middle, and lower sections of a 17 km long study reach, to monitor temperatures and bromide concentrations in the shallow ground water beneath the stream. A heat and ground water transport simulation model and a closely related solute and ground water transport simulation model were matched up for comparison of simulated and observed temperatures and bromide concentrations in the streambed. Vertical, one-dimensional simulations of sediment temperature were fitted to observed temperature results, to yield apparent streambed hydraulic conductivities in each cross section. The temperature-based hydraulic conductivities were assigned to a solute and ground water transport model to predict sediment bromide concentrations, during the sodium bromide injection test. Vertical, one-dimensional simulations of bromide concentrations in the sediments yielded a good match to the observed bromide concentrations, without adjustment of any model parameters except solute dispersivities. This indicates that, for the spatial and temporal scales examined on the Santa Clara River, the use of heat and bromide as tracers provide comparable information with respect to apparent hydraulic conductivities and fluxes for sediments near streams. In other settings, caution should be used due to differences in the nature of conservative (bromide) versus nonconservative (heat) tracers, particularly when preferential flowpaths are present.     

The status of the ecological environment and a proposed protection strategy in Sanya Bay,Hainan Island,China

Sanya Bay encompasses a high diversity of natural habitats, ranging from coral reefs, rocky and sandy shores and mudflats to mangroves. Seasonal physicochemical and biological investigations were conducted from 1998 to 1999 and again in April 2000. Water-related environmental quality in Sanya Bay is in good condition. The levels of dissolved oxygen, nitrogen, phosphorus and heavy metals are within the first class of National Seawater Quality Standards for China. Annual mean values of chlorophyll a of 0.93 mg m(-3) and phytoplankton primary productivity of 440.8 mgC m(-2)d(-1), respectively, were found in the waters, both of which show a significant correlation with inorganic nitrogen. A mean new productivity of 144.6 mgC m(-2) d(-1) was recorded in summer. Sanya Bay is rich in natural resources and biodiversity with 235 species of phytoplankton and 129 species of zooplankton identified in the survey. The annual mean abundance of phytoplankton and zooplankton were 1564 x 10 cells m(-3) and 121 individuals m(-3), respectively, with an annual mean zooplankton biomass of 129 mg m(-3). A total of 243 species of fish were sampled in the survey including many of high economic value. Three hundred and eighty-four species of benthos in 121 families were found by mud sampling and trawling. The average biomass of benthic organisms was 11.55 gm(-2), with a density of 31 individuals m(-2). Molluscs were the dominant group, followed by crustaceans; coelenterates exhibited the lowest biomass. One hundred and twenty-six species from 48 families of intertidal organisms were collected by frame sampling, with a mean annual biomass of 644.7 gm(-2) and average density of 816 individuals m(-2). The highest biomass of 1673.5 gm(-2) was collected in a coral reef region, while the highest density of 1219 individuals m(-2) occurred in a mangrove region. The coastline is characterized by coral reefs that accounts for 30% of the total coastline length in the bay, so coral reefs are a key ecosystem that are important for maintaining the regional marine resources and biodiversity. We need to pay much more attention to such diverse marine resources to maintain the integrity and function of these coastal ecosystems.     

A candidate of the Induan-Olenekian boundary stratotype in the Tethyan region

The Olenekian Stage was proposed by Kiparisova and Popov[1] based on the type section along the lower reaches of the Olenek River, Siberia. Later research showed that this section con-tains only the Olenikites spiniplicatus Zone of the Upper Olenekian Sta…     

Trace elements in skin of Dall's porpoises (Phocoenoides dalli) from the northern waters of Japan: an evaluation for utilization as non-lethal tracers

Concentrations of Fe, Zn, Cu, Se, Mn, Mo, Hg, Cd, Cr, Ag, Pb, Sr and V were determined in skins of Dall's porpoises (Phocoenoides dalli) of the Pacific coast truei-type population (PT population) (N=45), and the Sea of Japan-Okhotsk dalli-type population (JD population) (N=31) from the northern waters of Japan. Cutaneous Hg concentrations in both PT and JD populations were significantly correlated with age, indicating a possible alternative method of age estimation. A significant correlation was also noted between Hg concentrations in skin and liver, suggesting that biopsy samples of skin can provide a non-lethal surrogate for monitoring Hg contamination in this species. Trace element accumulation patterns differed strongly between PT and JD populations, when analyzed by principal component analysis, suggesting these patterns could be utilized as non-lethal tracers of population identification.     

Effects of antifouling paint components (TBTO,copper and triazine) on the early development of embryos in cod (Gadus morhua L.)

To assess the risk of antifoulant use to the commercially important cod (Gadus morhua L.), fertilised cod eggs were exposed to triazine, copper and TBTO singly or combined in laboratory tests with running seawater. At the highest tested concentrations (11.5 microg Cu l(-1); 5 microg TBTO l(-1)) larval mortality was increased. The highest concentration of triazine (40 microg l(-1)) did not cause any significant mortality. Fertilised eggs that had been exposed to all the three chemicals singly for five days showed a higher buoyancy than the controls. No synergistic or antagonistic effects were indicated. Embryos/larvae exposed to 0.004-0.8 microg TBTO l(-1) did not show any changed respiration compared to the controls after hatching. It is concluded that existing known field concentrations of the three antifoulants are hardly expected to cause detectable effects on fish embryonic/larval development.