Southern California Area Research Articles

Temporal Changes in the Vertical Distribution of Flow and Chloride in Deep Wells

The combination of flowmeter and depth-dependent water-quality data was used to evaluate the quantity and source of high-chloride water yielded from different depths to eight production wells in the Pleasant Valley area of southern California. The wells were screened from 117 to 437 m below land surface, and in most cases, flow from the aquifer into the wells was not uniformly distributed throughout the well screen. Wells having as little as 6 m of screen in the overlying upper aquifer system yielded as much as 50% of their water from the upper system during drought periods, while the deeper parts of the well screens yielded 15% or less of the total yield of the wells. Mixing of water within wells during pumping degraded higher-quality water with poorer-quality water from deeper depths, and in some cases with poorer-quality water from the overlying upper aquifer system. Changes in the mixture of water within a well, resulting from changes in the distribution of flow into the well, changed the quality of water from the surface discharge of wells over time. The combination of flowmeter and depth-dependent water quality data yielded information about sources of high-chloride water to wells that was not available on the basis of samples collected from nearby observation wells. Changing well design to eliminate small quantities of poor-quality water from deeper parts of the well may improve the quality of water from some wells without greatly reducing well yield.

VISITOR VALUES AND LOCAL ECONOMIC IMPACTS OF RIPARIAN HABITAT PRESERVATION: CALIFORNIA'S KERN RIVER PRESERVE

Preservation of the few remaining ecologically vital riparian areas in the southwestern United States is a significant policy concern. This article reports on two economic aspects of pre- serving a nationally renowned riparian birding area in Southern California. First, the article examines visitor willingness to pay (WTP) for habitat restoration and estimates an annual WTP of US$77 per visitor to preserve the habitat, about a half-million dol- lars a year for estimated visitor numbers in 2000 and 2001. Second, it documents visitor expenditures in the local economy to be approximately three-quarters of a million dollars per year. This direct visitor spending attributable to the riparian habitat gener- ates around US$1.3 million in increased local business activity in this relatively remote rural area. (KEY TERMS: economics; willingness to pay; expenditures; water allocation; recreation; birding.)

GROUND WATER/SURFACE WATER RESPONSES TO GLOBAL CLIMATE SIMULATIONS, SANTA CLARA-CALLEGUAS BASIN, VENTURA, CALIFORNIA

ABSTRACT: Climate variations can play an important, if not always crucial, role in successful conjunctive management of ground water and surface water resources. This will require accurate accounting of the links between variations in climate, recharge, and withdrawal from the resource systems, accurate projection or predictions of the climate variations, and accurate simulation of the responses of the resource systems. To assess linkages and predictability of climate influences on conjunctive management, global climate model (GCM) simulated precipitation rates were used to estimate inflows and outflows from a regional ground water model (RGWM) of the coastal aquifers of the Santa Clara-Calleguas Basin at Ventura, California, for 1950 to 1993. Interannual to interdecadal time scales of the El Niño Southern Oscillation (ENSO) and Pacific Decadal Oscillation (PDO) climate variations are imparted to simulated precipitation variations in the Southern California area and are realistically imparted to the simulated ground water level variations through the climate-driven recharge (and discharge) variations. For example, the simulated average ground water level response at a key observation well in the basin to ENSO variations of tropical Pacific sea surface temperatures is 1.2 m/°C, compared to 0.9 m/°C in observations. This close agreement shows that the GCM-RGWM combination can translate global scale climate variations into realistic local ground water responses. Probability distributions of simulated ground water level excursions above a local water level threshold for potential seawater intrusion compare well to the corresponding distributions from observations and historical RGWM simulations, demonstrating the combination's potential usefulness for water management and planning. Thus the GCM-RGWM combination could be used for planning purposes and — when the GCM forecast skills are adequate — for near term predictions.

Comparison of velocity‐log data collected using impeller and electromagnetic flowmeters

Previous studies have used flowmeters in environments that are within the expectations of their published ranges. Electromagnetic flowmeters have a published range from 0.1 to 79.0 m/min, and impeller flowmeters have a published range from 1.2 to 61.0 m/min. Velocity-log data collected in five long-screened production wells in the Pleasant Valley area of southern California showed that (1) electromagnetic flowmeter results were comparable within +/-2% to results obtained using an impeller flowmeter for comparable depths; (2) the measured velocities from the electromagnetic flowmeter were up to 36% greater than the published maximum range; and (3) both data sets, collected without the use of centralizers or flow diverters, produced comparable and interpretable results. Although either method is acceptable for measuring wellbore velocities and the distribution of flow, the electromagnetic flowmeter enables collection of data over a now greater range of flows. In addition, changes in fluid temperature and fluid resistivity, collected as part of the electromagnetic flowmeter log, are useful in the identification of flow and hydrogeologic interpretation.

Local Perception of Public Goods: Recent Assessments of Willingness-to-pay for Endangered Species

I. INTRODUCTION Biological diversity has become a controversial issue in Orange County, California. Recent Endangered Species Act (ESA) critical habitat designations covering some 85,000 acres in the county have been subject several court cases. (1) Questions about both the direct and indirect costs of preserving endangered species are being raised, yet there has been little attention the benefits of biodiversity. This study offers contingent valuation estimates of local residents' willingness pay for several controversial species. It also provides estimates of the aggregate benefits from species protection for future policy discussion. The critical habitat for the Arroyo toad, (2) the Riverside fairy shrimp, the California gnatcatcher, and the tidewater goby (originally designated in 2000) covered a large swath of coastal sage scrub and other grasslands, vernal pools, rivers, and streams of southern California. Some areas overlap those relevant some of the other endangered species in Orange County, such as the Southern California steelhead trout, the Santa Ana sucker, the southwestern willow flycatcher, least Bell's vireo, and the Pacific pocket mouse, among others. Environmental organizations state that habitat designations are necessary prevent fragmented species habitat, severed wildlife corridors, damaged watersheds, and further urban sprawl. But clear opposition the designations has arisen from some landowners, developers, and tollway planners. They suggest housing or road building projects--which require federal permits--may be halted because the land in question, although private, is now critical habitat. This could reduce the number of newly constructed units and raise the price of permitted building. Additional consultation costs could follow. Broader debates about the future of the ESA are also emerging. The ESA, first passed in 1973, has aimed address the market failure of the underpriced social benefits of endangered species. The Act allows staff of the U.S. Fish and Wildlife Service (FWS) or the National Marine Fisheries Service list an animal or plant species as endangered or threatened. Critical habitat designations are supposed follow promptly after listing (yet rarely do). These targeted species enjoy strong protections through the ESA's section 9 that prohibits any taking of the species; section 7 also requires federal agencies (or private parties obtaining federal permits) ensure that any action they authorize, fund, or carry out will not jeopardize the existence of the species or adversely modify its critical habitat. The FWS aims eventually delist endangered species through the implementation of recovery plans and restoration efforts written by scientists knowledgeable about species history, status, and threats. Currently, traditional cost-benefit analyses of listing or habitat decisions do not occur. A 1978 amendment the ESA requires some economic analysis at the critical habitat stage; areas may be excluded if the benefits of exclusion outweigh the benefits of specifying the area as habitat, unless the failure designate leads species extinction. Direct costs of species recovery appear quite modest in many of the published recovery plans. The recovery plans are vague regarding expensive private land acquisition with much of the cost secure pools and other lands to be determined. But the indirect (opportunity) costs of housing and transportation development opportunities forgone on critical habitat areas remain the largest source of controversy in the West. Changing land use designations represent a transfer of present producer/consumer surplus future generations, and calculation difficulties usually preclude including these opportunity costs in policy making. (3) Despite the press coverage of the spotted owl and Klamath River debates, little attention has been paid the potential benefits of species preservation in southern California and other areas of the West affected by the recent habitat designations. …

The Role of the Unsaturated Zone in Artificial Recharge at San Gorgonio Pass, California

The hydrogeology of the unsaturated zone plays a critical role in determining the suitability of a site for artificial recharge. Optimally, a suitable site has highly permeable soils, a capacity for horizontal flow at the aquifer boundary, a lack of impeding layers, and a thick unsaturated zone. The suitability of a site is often determined by field and laboratory measurements of soil properties, field experiments, and numerical modeling. An artificial recharge site in the San Gorgonio Pass area in southern California, USA was studied to better understand the role of the unsaturated zone in artificial recharge by surface spreading. Field measurements and observations were used to characterize the site and to develop a conceptual model of the unsaturated zone. A numerical model was developed based on the conceptual model and calibrated using data from a 50-d artificial recharge experiment conducted in 1991 and borehole data collected between 1997 and 2002. Results indicate that an impeding layer exists 70 m below land surface that will cause lateral diversion of artificially recharged water, which would spread out and delay recharge to the water table 185 m below land surface.

Rapid Assessment Survey for Exotic Organisms in Southern California Bays and Harbors, and Abundance in Port and Non-port Areas

In recent decades, the world has witnessed an array of harmful invasions by exotic marine organisms. To provide the public and policymakers with better information on the status of exotic species in southern California waters, and to assess differences between port and non-port areas, a Rapid Assessment Survey of selected habitat types in sheltered waters between San Diego and Oxnard was conducted in the summer of 2000. The objectives included comparing the prevalence of exotic species among habitats and regions and between recent and past surveys; obtaining reference data for future assessments of changes in invasion status and the effectiveness of prevention or control efforts; detecting new invasions; and documenting significant range extensions. Twenty-two sites were sampled to include the three major commercial port areas in southern California, non-port-area marinas and lagoon sites. Sampling included dock fouling and adjacent soft-bottom benthos, nearby intertidal sites, and selected subtidal lagoon habitats. Samples were collected by a variety of manual techniques. Sixty-nine of the species collected are exotic, including representatives from two algal divisions and six invertebrate phyla. Ascidians are especially well-represented (14 exotic species) and widely occurring, and some bivalves and bryozoans also occur very widely. The numbers and proportions of exotic taxa were not significantly greater in port areas than in non-port areas.

サリナスバレーにおける野菜栽培とサラダ加工会社の広域的展開

Salinas Valley, California, is the leading lettuce-producing area in the United States. Production, processing and marketing of vegetables based in Salinas Valley are typical of the industrialized farming in the United States. This article intends to depict the dynamics of American agriculture by examining the activities of agribusiness with special reference to farming practices, land use, salad processing, and labor. Field studies were conducted in Salinas Valley and Imperial Valley.Production of lettuce in Salinas Valley began in the early 1920s when ice-packed lettuce began to be shipped by rail to the eastern market. Lettuce growers originally marketed lettuce in the spring, summer, and fall from Salinas Valley. From the mid-1920s they began winter harvesting of lettuce in the dry areas of southern California and Arizona, typically in Imperial Valley and Yuma Valley. With the completion of the California Aqueduct, Huron in the western part of San Joaquin Valley grew as a new lettuce-producing area in the 1970s to supply lettuce in April and October. The system of year-round production of vegetables was thus established in the 1970s. Outside capital was invested in Salinas Valley during this period to promote the agribusiness venture of lettuce production and marketing. Some growers shifted to processing ready-pack fresh vegetables in the 1980s by establishing large plants in Salinas Valley.The system of year-round supply of vegetables in Salinas Valley, Imperial Valley-Yuma Valley, and western San Joaquin Valley makes this part of the United States the leading produc of fresh vegetables in the world. Differences in climatic conditions, modern technology for preserving and transporting fresh vegetables, influx of large amounts of capital, availability of cheap labor, and improved infrastructure have combined to create this production complex. It plays an important role in the global supply of fresh vegetables as the produce is consumed not only in North America but also in Europe and Asia, including Japan.

Did a local distribution company procure prudently during the California electricity crisis?

To manage cost risk, prudent procurement of electric power requires that some portion of a buyer's energy demand be met through long-term contracting. Under cost-of-service regulation or performance-based regulation, a local distribution company (LDC) should be allowed to fully recover all prudently incurred power procurement costs. However, the regulatory test of prudence is an ex post review with the threat of disallowance. This paper presents an economic analysis of procurement prudence involving a small LDC, Bear Valley Electric Service (BVES), which serves a resort area in Southern California. The key findings are: (a) high and volatile prices and rolling blackouts characterized the market environment faced by the owner of BVES, Southern California Water Company (SCWC), at its signing of a 5-year fixed price contract; (b) SCWC was a price-taker with no incentive to act imprudently; (c) the contract was obtained via a competitive bidding process; (d) the contract price was comparable to the benchmark price of contemporaneous contracts; (e) the fixed price contract was economic when compared to available alternatives; and (f) despite (a)–(e), a negotiated settlement with the state regulator and a large user resulted in substantial disallowance. The policy implication is that a regulator should approve a prudent procurement plan proposed by an LDC to remove the unreasonable risk of an ex post review. If the LDC strictly adheres to the plan, the resulting electricity purchases are per se prudent and should entitle the LDC to full cost recovery.

Inequality of Access to Surgical Specialty Health Care: Why Children With Government-Funded Insurance Have Less Access Than Those With Private Insurance in Southern California

More than 25 million children in the United States are dependent on federal and state medical insurance programs for their health care needs. In California, 3.25 million children depend on Medi-Cal for their health insurance. In Southern California alone, the figure is as high as 1.81 million. However, 9.30 million children nationally and 1.55 million in California have no health insurance. Various public policies that would increase enrollment in these programs are being discussed to address this problem. However, before their implementation, it is important to understand what impact such policies would have on the actual delivery of health care to this patient population. In California, 2 predominant health care delivery models exist for Medi-Cal: a fee-for-service (so-called regular or straight Medi-Cal) and a managed care plan. One third of the children in Medi-Cal in the state are enrolled in the fee-for-service plan with the remainder in the managed care plan, whereas in Southern California, this figure is slightly lower at 28% in the fee-for-service plan. The objective of this study was to determine the number of otolaryngologists in Southern California who would offer a new patient appointment for an evaluation for tonsillectomy for a child with commercial insurance versus government-funded (Medi-Cal) insurance through direct contact with the physician and to determine whether the surgeon would offer to perform the procedure or refer the patient to another institution and to identify the specific reason(s) for any disparity in access to health care. A written questionnaire was sent via regular mail to 303 otolaryngologists in the Southern California area in 2003. A total of 100 fully completed questionnaires were received. Ninety-seven surgeons would offer an office appointment to a child with commercial insurance as compared with only 27 for a child with Medi-Cal. Of those 27 surgeons, 8 would then refer the child to another physician to perform the surgery, and only 19 would actually offer to perform surgery, if indicated. Reasons provided for not offering an office appointment or surgery for the child with Medi-Cal include excessive paperwork and/or administrative burdens (96%), low monetary reimbursement for the surgery (92%), and low monetary reimbursement for the office visit (87%). There is a tremendous inequality of access to surgical specialty health care for children with government-funded insurance when compared with those with commercial insurance in Southern California. Physicians indicate that this disparity is related to excessive administrative burdens and low monetary reimbursement. The implications of our findings on public health care policies are discussed.

The Role of the Unsaturated Zone in Artificial Recharge at San Gorgonio Pass, California

The hydrogeology of the unsaturated zone plays a critical role in determining the suitability of a site for artificial recharge. Optimally, a suitable site has highly permeable soils, a capacity for horizontal flow at the aquifer boundary, a lack of impeding layers, and a thick unsaturated zone. The suitability of a site is often determined by field and laboratory measurements of soil properties, field experiments, and numerical modeling. An artificial recharge site in the San Gorgonio Pass area in southern California, USA was studied to better understand the role of the unsaturated zone in artificial recharge by surface spreading. Field measurements and observations were used to characterize the site and to develop a conceptual model of the unsaturated zone. A numerical model was developed based on the conceptual model and calibrated using data from a 50‐d artificial recharge experiment conducted in 1991 and borehole data collected between 1997 and 2002. Results indicate that an impeding layer exists 70 m below land surface that will cause lateral diversion of artificially recharged water, which would spread out and delay recharge to the water table 185 m below land surface.

Electricity price and Southern California’s water supply options

This paper evaluates the impact of fluctuating electricity prices on the cost of five options to increase the water supply to urban areas in Southern California—new surface storage, water purchases, desalination, wastewater recycling, and conservation. We show that the price of electricity required to produce and transport water influences the cost of water supply options and may alter the decision makers economic ranking of these options. When electricity prices are low, water purchase is the cost effective option. When prices exceed US$ 86/MWh, conservation of electricity and water through installation of high efficiency clothes washers is the most effective option.

Annual phytoplankton production in a coastal lagoon of the southern California Current System

Seasonal and annual integrated phytoplankton production (AIP) of a shallow lagoon of the NW coast of Baja California, Estero de Punta Banda, was estimated during inverse-estuarine con- ditions in 1998 and 1999, a non-El Nino year. Estero de Punta Banda is a coastal lagoon with no city/industrial waste input; its primary production is comparable to that of impacted coastal bodies such as those in the Southern California area. To calculate AIP, we used representative averages of chlorophyll a concentration for 2 regions within the lagoon (outer and inner), representative averages of the photosynthetic parameters, an atmospheric model to estimate photosynthetically available radiation (PAR), and multiple linear regression models for the vertical attenuation coefficient of PAR (K PAR) as a function of wind speed and tidal range. The seasonal average daily integrated primary production was highest in summer (880 and 47 mgC m -2 d -1 for the outer and inner regions, respec- tively), due to higher temperature and light levels, as is generally reported for other temperate estu- aries. Values in winter were about half those in summer. Average AIP for the whole lagoon (125 gC m -2 yr -1 ) was relatively low compared with estimates for larger, deeper and/or sewage- enriched coastal water bodies. This was mainly due to the shallow integration depth of AIP in our study area and to high turbidity caused by tidal currents and wind waves.

Determining the foraging range and origin of resurgence after treatment of Argentine ant (Hymenoptera: Formicidae) in urban areas.

The foraging range and distribution of Argentine ant, Linepithema humile (Mayr), colonies in urban areas of southern California extended at least 61 m (200 feet) from feeding stations and structures. Ants were fed at 25% sucrose feeding stations containing 0.01% fluorescent brighter (FB28). Within 14 d, from 77-90% of the ants sampled next to the feeding stations were positive for FB28. The percentage of ants with FB28 declined gradually to approximately 55% 61 m away from the feeding station. The percentage of marked ants in the controls didn't change over the 4-wk-test period. There were approximately 290,000 ants visiting the monitored stations each night before treatments. The 0.0001% fipronil baits and 0.06% fipronil SC sprays provided significant reductions in at least 4 wk. The percentage of ants marked with FB28 decreased significantly in both bait and spray treatments over 4 wk suggesting that the resurgence of ants in treated areas were because of immigration from untreated areas. It is likely that much larger areas will need to be treated to control Argentine ants in urban settings, especially if baits are being used.

Environmentally driven variation in ancient populations of turritellids: evaluating the causal link

Understanding the response of a species or lineage to long-term environmental change is a critical aspect of evolutionary paleoecology. In order to do this, paleobiologists must have an excellent fossil record of a lineage and an independent source of environmental data in the same region. This situation occurs in the San Pedro area of southern California, where relatively new paleotemperature and paleoproductivity records enhance the well-known fossil gastropod record. We quantified shell morphology of late Pleistocene and Recent turritellid gastropods from this area and compared the timing of changes with temperature and productivity reconstructions for the region. Our results indicate that warm temperatures and moderate to high productivity are associated with larger shells and wider whorls. Cold temperatures and lower productivity are associated with smaller, narrower shells. We propose that warm temperatures and moderate productivity result in higher growth rates in turritellid gastropods. Our work also suggests that below a certain threshold temperature, productivity appears to have no influence on shell morphology. In other words, growth rate is unaffected by high productivity unless average temperatures are above a certain level. These results are consistent with models of shell deposition and with experimental results from living gastropods and bivalves reported in the literature.

The Roots of Resistance: Cultivating Critical Parental Involvement

The three voices above belong to immigrant, working-class women who have become leaders in the struggle to create an empowering education for their children and their neighborhoods. In most schools that serve poor and working-class students of color, parents are systematically shut out of meaningful participation in their children's education. Working-class parents are welcomed in schools insofar as they do not question the power relations or the nature of the oppression that pervades schooling. In contrast, during the past seven years, I have been involved in a community movement to change two elementary schools in the Southern California area. This movement is led by Latina immigrant mothers. Through my work with these mothers, I have developed a theoretical model based on parental involvement that can be used by other educational activists. I call this model Critical Parental Involvement. This model is based on two key processes – critical analysis, and collective social action and reflection - that ...

Ozone transport by mesoscale and diurnal wind circulations across southern California

This paper reviews sea level and elevated surface observations from Point Mugu and nearby Laguna Peak in southern Ventura County, rawin/ozonesonde data from Point Mugu, and aircraft measurements in the coastal zone and offshore obtained in support of the SCOS97-NARSTO effort. Streamline analyses of SCOS97-NARSTO wind data are also presented, which reveal synoptic and mesoscale influences on air flow over the southern California area. Complex diurnal, mesoscale and synoptic wind patterns redistribute pollutants across air basins. The data show that southeasterly flow, often present from morning into early afternoon, and coastal eddies and southerly surges convey ozone and precursors westward and northward where they may appear aloft as layers with several times the concentration of ozone at the surface. This flow can transport South Coast Air Basin (SCAB) pollutants via mountain passes to the desert where mixing with pollution from the San Joaquin Valley can occur. Climatological evidence shows this tendency for southerly flow in the earlier part of the day is a recurrent feature of southern California wind patterns, and a major mechanism for transport of ozone and precursors from the SCAB to coastal, inland and desert regions to the north.

Using Spatially Explicit Data to Evaluate Marine Protected Areas for Abalone in Southern California

Abstract: Abalone populations have declined dramatically in southern California. The white abalone ( Haliotis sorenseni) is now ( 2001) on the federal endangered species list. To aid in the restoration of white, pink ( H. corrugata), and green abalone ( H. fulgens), productive marine protected areas need to be selected. We used spatially explicit fishery data (1950–1995) to identify the most productive marine areas in southern California. To assess the role of existing marine protected areas we compared fishery‐independent data (1983–2001) inside protected and fished areas. San Clemente Island produced the greatest cumulative catches of white, pink, and green abalone, the most white abalone per hectare of deep reef (25–65 m), and the most green abalone per kilometer of rocky shoreline. Santa Barbara Island, however, produced 10 times more pink abalone per hectare of kelp canopy, making this area an excellent candidate for restoration and protection. Pink abalone surveyed in the Kelp Forest Monitoring Program were most abundant at three sites surrounding Anacapa Island: (1) protected, (2) protected but less visible, and (3) fished. The protected sites, despite having lower abundances of pink abalone initially (1983), had significantly more abalone ( H = 9.0; df = 2; p = 0.011) than the nearby fished site over time. Size‐frequency distributions revealed that the protected site had more (30%) commercial‐size abalone (≥158 mm shell length) than the less visable site (6%) or the fished site (2%). Mean size was significantly larger at the protected site, yielding the highest estimate of biomass and potential egg production (2555 million eggs/site/year) of all the sites. Marine protected areas need to be selected and enforced so that abalone‐restoration efforts can be enacted before remnant populations die. Restoration sites for a wide variety of depleted species can be selected based on previous levels of productivity identified by spatially explicit data.

Association of asthma symptoms with peak particulate air pollution and effect modification by anti-inflammatory medication use.

Maxima of hourly data from outdoor monitors may capture adverse effects of outdoor particulate matter (PM) exposures in asthmatic children better than do 24-hr PM averages, which form the basis of current regulations in the United States. Also, asthmatic children on anti-inflammatory medications may be protected against the proinflammatory effects of air pollutants and aeroallergens. We examined strengths of pollutant associations with asthma symptoms between subgroups of asthmatic children who were on versus not on regularly scheduled anti-inflammatory medications, and tested associations for different particle averaging times. This is a daily panel study of 22 asthmatic children (9-19 years of age) followed March through April 1996 (1,248 person-days). They lived in nonsmoking households in a semirural area of Southern California within the air inversion mixing zone (range, 1,200-2,100 feet) with transported air pollution from urban areas of Southern California. The dependent variable derived from diary ordinal scores is episodes of asthma symptoms that interfered with daily activities. Minimum to 90th-percentile levels of exposures at the outdoor monitoring site were 12-63 microg/m(3) for 1-hr PM < 10 microm in aerodynamic diameter (PM(10)); 8-46 microg/m(3) for 8-hr PM(10); 7-32 microg/m(3) for 24-hr PM(10); 45-88 ppb for 1-hr O(3); 6-26 ppb for 8-hr NO(2); 70-4,714 particles/m(3) for 12-hr daytime fungi; and 12-744 particles/m(3) for 24-hr pollen. Data were analyzed with generalized estimating equations controlling for autocorrelation. There was no confounding by weather, day of week, or linear time trend. Associations were notably stronger in 12 asthmatic children who were not taking anti-inflammatory medications versus 10 subjects who were. Odds ratios (95% confidence intervals) for asthma episodes in relation to lag 0 minimum to 90th-percentile pollutant changes were, respectively, 1-hr maximum PM(10), 1.92 (1.22-3.02) versus 0.96 (0.25-3.69); 8-hr maximum PM(10), 1.68 (0.91-3.09) versus 0.75 (0.18-3.04); 24-hr average PM(10), 1.35 (0.82-2.22) versus 0.80 (0.24-2.69); 1-hr maximum O(3), 1.28 (0.75-2.17) versus 0.76 (0.24-2.44); 8-hr maximum NO(2), 1.91 (1.07-3.39) versus 1.08 (0.30-3.93); 12-hr fungi, 1.89 (1.24-2.89) versus 0.90 (0.35-2.30); 24-hr pollen, 1.90 (0.99-3.67) versus 0.85 (0.18-3.91). Pollutant associations were stronger during respiratory infections in subjects not on anti-inflammatory medications. Although lag 0 1-hr maximum PM(10) showed the strongest association, the most robust associations were for lag 0 and 3-day moving averages (lags 0-2) of 8-hr maximum and 24-hr mean PM(10) in sensitivity analyses testing for thresholds. Most pollutant effects were largely driven by concentrations in the upper quintile. The divergence of exposure-response relationships by anti-inflammatory medication use is consistent with experimental data on inflammatory mechanisms of airborne pollutants and allergens.

Alternative Irrigation Systems for Arid Land Restoration

Establishing plants in deserts can be challenging even with supplemental irrigation. The low relative humidity, extreme temperatures, lack of consistent rainfall, tremendous rate of evaporation, and high wind speeds common in desert environments all play important and interrelated roles in water loss from desert soil and plants. These factors make it critical that restorationists use the most appropriate and cost-effective means to deliver water to the root zone of newly planted plants in order to maximize survival and growth. In this paper, I discuss the pros and cons of standard and alternative means of watering plants. This information is derived from experiences that my colleagues and I have had using these systems in the desert areas of southern California and from the experiences of researchers in other countries.