Metals in seafood organisms near a large California municipal outfall

With the possible exception of copper and zinc, eight trace metals in muscle tissue of five popular benthic-feeding sportsfishes caught near the Los Angeles County municipal wastewater outfalls were not concentrated above levels measured in island and coastal control specimens. In contrast, the edible portions of five invertebrate seafood organisms collected from the highly contaminated bottom sediments in this discharge zone did concentrate some of the metals several-fold above control values. The maximum contamination observed was a 10-fold elevation of chromium in abalone and scallop muscle.     

Observations and estimation of long-period strong ground motion in the los angeles basin

While the accurate estimation of ground-motion amplitudes across the entire frequency band of engineering interest is not possible at the present time, the excitation and propagation of long-period strong-ground motion can be understood with existing seismological methodology. In the Los Angeles Basin, the long-period strong ground motion excited by the San Fernando earthquake is dominated by the presence of surface waves, whose gross amplitude and frequency content are easily attributable to physical properties of the earthquake source and source-station propagation paths. Observed measures of the long-period strong ground motion of the Kern County earthquake relative to the San Fernando earthquake at two sites in the Los Angeles Basin which recorded both shocks can be predicted with considerable accuracy by a simple earthquake source model. This source model is extrapolated to represent the maximum credible earthquake likely to affect the Los Angeles area, taken to be a repeat of the Fort Tejon (1857) earthquake along the San Andreas fault. The measures of long-period strong ground motion in the Los Angeles Basin estimated for it agree well with the comparable measures of Earthquake A-2, intended to represent the same situation. For the purpose of aseismic design of long-period structures, Earthquake A-2 is a reasonable, if not all inclusive, estimate of the long-period strong ground motion in the Los Angeles Basin generated by a magnitude 8+ earthquake along the San Andreas fault north and east of Los Angeles.     

Predicting the bioaccumulation of organic compounds in marine organisms using octanol/water partition coefficients

Sediments and animals collected from near the discharge zone of the Los Angeles County wastewater treatment plant were analysed for 27 selected organic compounds that had been identified in the effluent. It was found that the sediment and tissue concentrations of these organic compounds were positively correlated with each other and with the n-octanol/water partition coefficient but that these were negatively correlated with the effluent concentration. It was concluded that n-octanol/water partition coefficients should be used to predict which organics have the potential to bioaccumulate and therefore cause biological effects.     

Northridge, California, earthquake of 1994: density of pipe breaks and surface strains

Empirical scaling equations are presented which relate the average number of water pipe breaks per km², , with the peak strain in the soil or intensity of shaking at the site. These equations are based on contour maps of peak surface strain evaluated from strong motion recordings, and observations of intensity of ground shaking and damage following the Northridge, California, earthquake of 17 January 1994. Histograms for the number of pipe breaks per km², n, are presented for several ranges of values of the horizontal peak strain and for several values of the site intensity. The observed distribution of pipe breaks is also used to speculate on possible more detailed geographical distribution of near surface strains in the San Fernando Valley and in central Los Angeles. The results can be used to predict number of pipe breaks in the San Fernando Valley and in Los Angeles, for a scenario earthquake or in probabilistic seismic hazard calculations, considering all possible scenarios that contribute to the hazard and the likelihood of their occurrence during specified exposure. Such predictions will be useful for emergency response planning (as the functioning of the water supply is critical for sanitation and in fighting fires caused by earthquakes), to estimate strains during future and past earthquakes in areas where no strong motion was recorded and in defining design guidelines for pipelines and other structures and structural systems sensitive to strains in the ground.     

An application of contingent valuation and decision tree analysis to water quality improvements

This paper applies contingent valuation and decision tree analysis to investigate public preferences for water quality improvements, and in particular reduced eutrophication. Such preferences are important given that the development of EU water quality legislation is imposing significant costs on European economies. Results are reported of a survey undertaken of residents of Århus County, Denmark for water quality improvements in the Randers Fjord. Results demonstrate strong public support for reduced eutrophication and identify key determinants of such support.     

An application of contingent valuation and decision tree analysis to water quality improvements

This paper applies contingent valuation and decision tree analysis to investigate public preferences for water quality improvements, and in particular reduced eutrophication. Such preferences are important given that the development of EU water quality legislation is imposing significant costs on European economies. Results are reported of a survey undertaken of residents of Arhus County, Denmark for water quality improvements in the Randers Fjord. Results demonstrate strong public support for reduced eutrophication and identify key determinants of such support.     

Ground Water Replenishment with Reclaimed Water in the City of Los Angeles

A two-year pilot study involving the recharge of a ground water basin with reclaimed water was completed in the city of Los Angeles. The city's Department of Water and Power is planning to initiate several ground water recharge projects using reclaimed water in the near future. One such project is the Headworks Recharge Project, the focus of this paper, Approximately 1 cfs of the Los Angeles (LA) River water comprised of 70% tertiary treated reclaimed water was recharged on a two-day wet and five-day dry cycle. The recharge water was then extracted from the basin approximately 1000 feet downgradient. Results showed greater than 4-log removal of coliform bacteria, up to 87% reduction in TOC, and compliance of the product water with federal and state drinking water standards. Model simulation showed after 15 years of recharging 3000 acre-feet per year of the LA River water and extracting about 10,000 acre-feet from the basin, the product water would contain from 5% to 15% reclaimed water. This is well below the maximum allowable limit of 20% stipulated by the California regulation.     

On the transmissivity of the atmosphere in the water vapour absorption (6–6.5 μ) band

Summary The atmospheric transmissivity in the water vapour absorption band (6–6.5 ) is evaluated using the recent Tiros III data and based onGoody's statistical model.Work completed while on leave from the Department of Meteorology, University of California, Los Angeles.     

Concentrations of methyl- tert-butyl ether (MTBE) in inputs and receiving waters of Southern California.

The occurrence and concentration of the fuel additive methyl-tert-butyl ether (MTBE) were measured in dry weather runoff, municipal wastewater and industrial effluents, and coastal receiving waters in southern California. Combined, refineries and sewage treatment plants release approximately 214 kg day(-1) of MTBE into the marine environment, with Santa Monica Bay receiving most (98%) of this discharge. Dry weather urban runoff was analysed for samples collected from 25 streams and rivers, and accounted for less than 0.5% of the mass of MTBE discharged to coastal waters. Receiving water samples were collected from 23 stations in Santa Monica Bay, Los Angeles Harbour and Mission Bay or San Diego Bay. MTBE was detected at low concentrations near effluent discharges, however there was no evidence of baywide MTBE contamination related to these outfalls. Marinas and areas used intensively for recreational boating had the highest average MTBE concentration (8.8 microg l(-1)). Surface water contamination was most widespread in San Diego Bay and Mission Bay, areas with no refinery or sewage treatment plant inputs.     

DDTs in marine fishes following termination of dominant California input: 1970–77

Through source control, total DDT annual emissions from the Los Angeles County Sanitation Districts' submarine outfalls decreased by a factor of 30 between 1971 and 1977 Here we report persistent elevated levels of DDT residues measured in three species of marine fishes with distinctly different feeding habits. Over the study interval, median levels of DDT residues have decreased 3-fold (8-fold and 4-fold from peak medians) in flesh of black perch and kelp bass. However, there was no apparent decrease in Dover sole. The sediment reservoir is the likely source of persistent contamination of fishes in the discharge area.     

Evidence of Strain Partitioning Between the Sierra Madre Fault and the Los Angeles Basin, Southern California from Numerical Models

— Geodetic data indicate that the northern Metropolitan Los Angeles region is shortening at a rate of 4.5–6.0 mm/yr between downtown Los Angeles and the San Gabriel Mountains. If we assume that all of the uplift of the San Gabriel Mountains is due to the major frontal fault system (the Sierra Madre fault) and use reported values for bedrock uplift, slip per event and recurrence intervals to determine the slip rate on the Sierra Madre fault, we obtain slip rates between 0.6–1.27 mm/yr. Using these slip rates, the horizontal shortening attributable to the Sierra Madre fault accounts for only ~33% of the observed shortening across the basin, leaving ~67% of the shortening to be accounted for elsewhere. Herein we present a suite of models that test possible shortening mechanisms to account for this strain deficit. The models incorporate a range of fault geometries and have a layered structure with variable vertical and horizontal rheologies. The models demonstrate how lower-crust rheology and the presence of a low rigidity, anelastically deforming sedimentary basin affects the dissipation of stress imposed on the viscous layers by elastic failure of the faults. We found that viscoelastic models with a single fault, vertically strong crust and a compliant sedimentary basin yield a horizontal velocity profile that best matches the geodetically observed velocity profile across the Los Angeles Basin. Our models also indicate that we are still not accounting for all of the observed deformation. Therefore, more complex models that include both laterally varying rheologies and frictional properties on faults must be considered.     

Effect of sampling frequency on shoreline microbiology assessments.

More than 80,000 shoreline bacteriological samples are collected annually in southern California to protect beachgoer health, but sampling frequency varies from daily to monthly among sampling sites. To assess the effectiveness of various sampling frequencies, we used five years of data from 24 Los Angeles area sites that have been monitored daily to simulate five alternative sampling strategies: five weekdays, five days per week including a weekend day, three days per week, weekly, and monthly. For each of these sampling strategies, we included in the simulation the local custom of adaptive sampling, in which a site is resampled the following day if bacterial concentrations exceed the State of California's beach water quality standards. We found that sampling five times per week resulted in observing about 80% of the events in which State standards were exceeded. This frequency dropped to 55%, 25%, and 5% for three times per week, weekly, and monthly sampling, respectively. Adaptive sampling was ineffective because nearly 70% of the water quality exceedences were single-day events, even at the most frequently contaminated sites. This high frequency of single-day events is of concern because the public is typically notified about water quality conditions 24-48 h after samples are collected, meaning that most warnings are out-of-date when they are issued.     

Metals in marine sediments near a large California municipal outfall

Elevated concentrations of trace metals in surficial sediments off Palos Verdes Peninsula, site of the Los Angeles County outfall system, clearly reflect the submarine discharge of treated municipal (domestic and industrial) wastewater. The following contamination factors (median outfall/median baseline) were obtained for the eight metals measured in a 45 km² region of the outfall monitoring zone: Ag-27; Cd-36; Cr-12; Cu-20; Hg-23; Ni-5.4; Pb-17; Zn-7.7.     

地震作用下核电站环行吊车动力响应特性的模拟分析

为评估地震作用下核电站环行吊车的动力响应特性,建立一个包含安全壳的简化核环吊有限元模型,数值模拟其在调幅的El Centro地震波作用下的受力特性,计算核环吊的固有频率特性,其中1阶固有频率为2.44 Hz。研究表明,在规范地震荷载作用下核环吊大梁的强度满足规范要求。在典型的三向Los Angeles地震动作用下,大车轮子与环轨之间始终处于受压状态,没有发生跳轨现象;小车轮子与大车主梁之间始终处于受压状态,也没有发生跳轨现象。与安全壳基础输入地震波的峰值相比,核环吊大梁跨中和吊车小梁跨中最大垂直加速度分别增加了107%和126%。     

Development of marine water quality criteria for the USA

The US Environmental Protection Agency has developed guidelines for deriving numerical national water quality criteria for the protection of aquatic organisms and their uses. These guidelines provide the method for deriving water quality criteria, including minimum data base requirements, data evaluation procedures, and calculations. The guidelines have been in place for a long time, and states have used them to derive water quality standards for their water bodies. More recent efforts have been directed towards the development of technical guidance based on the concept that bioassessment and biocriteria programs for estuaries and near coastal waters are interrelated and are critical components of comprehensive water resource protection and management. This is a holistic approach to protection and management, integrating biological assessments into traditional chemical and physical evaluations and augmenting the established water quality criteria. The method for deriving water quality criteria and the approach for biocriteria development for marine systems are described.     

Prospective scenarios of the saltwater intrusion in an estuary under climate change context using Bayesian neural networks

In recent decades, saltwater intrusion over some low-lying coastal regions was deteriorated by rising sea-level and decreasing streamflow in the context of climate change. Though physically-based hydrodynamic models are the most detailed means to simulate salinity processes, they are commonly restricted by data insufficiency issues both in spatial resolution and temporal lasting. This motivates us to build a statistical model enable simulation and scenario analysis for coastal salinity change with limited observations. A Bayesian neural network (BNN) model is built hereby to simulate salinity. It offers more precise estimation compared with the conventional artificial neural network. Meanwhile, the model gives the uncertainty behaviors of the final salinity simulation which is not available for other methods. Future scenarios of salinity change are constructed and analyzed in different time periods on the basis of the validated BNN model. Results indicate that the water quality over lower Pearl River is degrading along with more significant uncertainties. Further analysis suggests that streamflow alteration has a more direct impact on salinity variations than the sea-level change does. The method allows a profound analysis of the potential influence on water quality degradation in coastal and low-lying regions in support of water management and adaptation toward global climate change.     

Different communities,different perspectives: issues affecting residents’ response to a volcanic eruption in southern Iceland

This research investigates residents’ knowledge and perception of the Katla volcano and emergency response procedures in all rural and urban communities located in the eastern and southern Katla hazard zones. Using a questionnaire survey conducted in 2008, we demonstrate that there is an apparent difference between rural and urban communities' knowledge and perceptions, and identify some of the issues influencing residents’ perspectives and behaviour. All rural and most urban residents have an accurate knowledge of Katla, the proposed warning system and emergency response plan. Urban residents perceived the emergency response plan to be appropriate. In comparison, rural residents did not perceive the emergency response plan as appropriate. Rural residents stated that they would personally assess the situation before deciding on a course of action independent of the proposed plan. Livelihood connections and inherited knowledge affect rural residents’ ability and willingness to comply with the recommended procedures. Factors such as hazard knowledge, sense of community and attachment to place indicate that rural residents are more resilient to volcanic hazards. Based on our findings we recommend that emergency management agencies consider issues such as personal responsibility, neighbourliness and community involvement and cooperation, to develop and implement more appropriate volcanic risk mitigation strategies. In light of the recent Eyjafjallajökull eruptions, we provide a brief discussion on the 2010 emergency response. Although our findings are Iceland-specific, our recommendations may be applied internationally to other volcanic and disaster-prone regions.     

The water crisis in the gaza strip: prospects for resolution

Israel and the Palestinian Authority share the southern Mediterranean coastal aquifer. Long-term overexploitation in the Gaza Strip has resulted in a decreasing water table, accompanied by the degradation of its water quality. Due to high levels of salinity and nitrate and boron pollution, most of the ground water is inadequate for both domestic and agricultural consumption. The rapid rate of population growth in the Gaza Strip and dependence upon ground water as a single water source present a serious challenge for future political stability and economic development. Here, we integrate the results of geochemical studies and numerical modeling to postulate different management scenarios for joint management between Israel and the Palestinian Authority. The chemical and isotopic data show that most of the salinity phenomena in the Gaza Strip are derived from the natural flow of saline ground water from Israel toward the Gaza Strip. As a result, the southern coastal aquifer does not resemble a classic "upstream-downstream" dispute because Israel's pumping of the saline ground water reduces the salinization rates of ground water in the Gaza Strip. Simulation of different pumping scenarios using a monolayer, hydrodynamic, two-dimensional model (MARTHE) confirms the hypothesis that increasing pumping along the Gaza Strip border combined with a moderate reduction of pumping within the Gaza Strip would improve ground water quality within the Gaza Strip. We find that pumping the saline ground water for a source of reverse-osmosis desalination and then supplying the desalinated water to the Gaza Strip should be an essential component of a future joint management strategy between Israel and the Palestinian Authority.     

Applications of Dual-Wall Reverse-Circulation Drilling in Ground Water Exploration and Monitoring

Dual-wall reverse-circulation drilling uses flush-threaded double-wall drill pipe and high-pressure air to provide continuous return of formation and water samples. Cuttings and formation waters are not contaminated with drilling additives or mixed with other borehole material. Up-hole velocity of about 70 ft/sec provides reliable logging of water, mineral or contaminant-bearing strata. Water samples representative of specific strata may be airlifted or bailed to the surface.
In the percussion hammer system, dual-wall drill pipe is advanced through chiefly unconsolidated material by the percussion action of an above-ground pile hammer. The borehole is drilled and temporarily cased in one pass. Wells or monitoring devices are installed as the drill pipe is hydraulically retracted during construction. A rotary head may be adapted as an option to allow dual-wall rotary drilling into consolidated or crystalline formations through a percussion hammer drill string temporarily left in place as a conductor.
The complex geology and variety of geoenvironmental problems in southern California has provided a testing ground for dual-wall drilling on hazardous material site investigations. Several case histories have demonstrated the capabilities and versatility of this method, including: (1) the installation of 4-inch and 6-inch diameter gasoline monitoring and recovery wells through gravels and cobbles at a filling station where hollow-stem auger drilling failed; (2) the confirmation of a dry borehole initially drilled by direct rotary at a landfill; and (3) multiple installations of monitoring devices through municipal refuse at a city of Los Angeles landfill.