A Review of the limnology of and water quality standards for Lake Mead

1. The waters of Las Vegas Bay, a heavily utilized recreational resource, receive discharges from a variety of municipal and industrial waste sources. The U.S. Environmental Protection Agency has determined, on the basis of numerous studies, that the present water quality violates state and federal standards and constitutes a public nuisance. Consultants have advised the Sewage and Wastewater Advisory Committee that rapid abatement of the alleged pollution conditions can be achieved by an advanced wastewater treatment (AWT) plant. 2. The major problems in Las Vegas Bay are an objectionable water color, excessive turbidity, noxious odors, and oxygen depletion in certain portions of the water column. Previous studies indicate that these problems are due to the effect of Las Vegas Wash on the Bay, and that the problems decrease as distance increases from the Las Vegas Wash inflow. The Wash provides a source of nutrients for high levels of algal production, which, in turn, are responsible directly for the pollution perceived by the public. Conditions in Boulder Basin, as opposed to those in Las Vegas Bay, have not reached an objectionable eutrophic level. 3. Most of the previous studies point to industrial and municipal wastewater discharges as the ultimate source of nutrients entering the Bay. One advisor argues that the nutrients arise from soil eroded into the Bay. 4. Adherents of the first position suggest that removal of nutrients from wastewater will abate the problems in Las Vegas Bay. Adherents of the second position suggest that control of soil erosion is the only step that can mitigate these pollution problems. 5. The following deficiencies in these previous studies prevent the formulation of a dependable strategy for decreasing the excessive algal production in Las Vegas Bay to acceptable levels: (i.) There has been no detailed attempt to ascertain the fate of Las Vegas Wash inflow. The fact that the bulk of this inflow may leave the Bay in a well-defined current does not imply that partial mixing of the current with the Bay is not affecting algal production. The presence of enteric bacteria in the Bay suggests that partial mixing, in fact, is occurring. (ii.) A systematic series of algal bioessays has not been undertaken to ascertain directly which nutrients limit algal production. (iii.) Inputs of phosphorus other than via the Wash discharge have been neglected, particularly internal loading from the sediments to the water column. (iv.) The effect of changing water level on dilution of nutrients in Las Vegas Bay has been neglected, despite the fact that the water volume in the Bay has increased about 75% between 1967 and 1976. (v.) The standard of 0.5 mg 1-1 phosphorus established by the EPA for Las Vegas Wash water does not rest on adequate evidence that these levels are necessary or sufficient to abate the problems in Las Vegas Bay, but rather upon the predicted performance of AWT. (vi.) The studies have not been designed to predict changes in Las Vegas Bay following various alternative treatment strategies. 6. Ecological Research Associates initiated a field study of Las Vegas Bay and Boulder Basin (20-23 September 1976) to resolve certain discrepancies in previous studies and to provide supplemental information consistent with the short duration of the study. 7. Specific conductivity, temperature, pH, and oxygen profiles agreed with those collected by previous investigators. High conductivity values reflecting the presence of a well-defined current representing the Las Vegas Wash inflow were observed in Las Vegas Bay. However, this current was not detected at the mouth of the Bay in Boulder Basin. These results do not support the notion that the Wash inflow does not mix in the Bay, but the detailed investigation necessary to decide this issue could not be performed during the short time period of the study. 8. Virtually all dissolved phosphorus occurs in inorganic form and in very low concentrations, indicating that biologically-available phosphorus is cycling extremely rapidly and that the amount of analytically detectable soluble phosphorus may not be particularly relevant for determining the potential algal production. 9. Algal productivity measurements in September were lower than those of previous investigators by more than 90% in some cases. The discrepancy may represent differences in methodology or real decreases in algal production. Many hypotheses may be invoked to explain the results if the latter is the case, but insufficient evidence exists to distinguish between them. The results emphasize that important questions concerning the source and fate of inflowing nutrients remain to be answered, because previous studies cannot account unequivocally for this decrease in productivity. Severely eutrophic conditions were not observed in Las Vegas Bay during the course of this study. 10. Algal bioassays demonstrated that inner Las Vegas Bay algae are responsive to nitrogen because of the heavy phosphorus loading. Virgin Basin algae (and hence, presumably, Boulder Basin samples) are stimulated by addition of wastewater, nitrogen or phosphorus. Recalculated N:P ratios, based on previous studies, suggest that all Las Vegas Bay and Boulder Basin stations, except for the inner Bay, are most limited by phosphorus. The implication is that the middle and outer Bay and the Basin are sensitive to further loading of phosphorus. The uncertainty of decisions based upon nitrogen to phosphorus ratios is emphasized in this report. 11. Sediment analyses indicate that phosphorus is removed from the water by sedimentation. Proper standards for phosphorus concentrations in inflowing waters cannot be established without taking into account the role of phosphorus sedimentation in Las Vegas Bay. 12. The application of Vollenweider\u27s relationship to Las Vegas Bay suggests that, even if EPA standards of 0.5 mg 1-1 phosphorus were met in Las Vegas Wash, the reduction in loading obtainable from present day AWT technology is not sufficient to produce the desired conditions in Las Vegas Bay. In any case, the Vollenweider relationship does not constitute an adequate basis on which to decide an abatement strategy for Lake Mead. 13. AWT treatment of Las Vegas Wash wastewater cannot guarantee the eradication of problems in Las Vegas Bay, both because the exact initial source of the nutrients is not established fully (i.e., wastewater or erosion) and because the effect of reducing phosphorus concentrations to 0.5 mg 1-1 in the Wash cannot be predicted at present. The predictive relationship used by other consultants to justify AWT has not been applied correctly. The correct application of this relationship to the condition in Las Vegas Bay demonstrates, on the contrary, that AWT technology will not be sufficient. The enormous expense and deleterious side effects of AWT technology are not justified on the basis of existing data. 14. Numerous alternatives to AWT exist. Upgraded secondary wastewater treatment combined with biological stripping of both nitrogen and phosphorus in an expanded Las Vegas Wash marsh is the alternative that deserves special consideration. Control of soil erosion and partial discharge of treated wastes directly to Boulder Basin also should be considered in this scheme. 15. Any further study should be addressed to the following specific points: (i.) The extent to which Las Vegas Wash inflow mixes with Las Vegas Bay water must be determined more precisely. (ii.) The stimulating effect of eroded soil washed into the Bay on algal productivity must be determined. (iii.) The level of algal growth that can be supported by water equivalent to that produced by various treatment strategies must be determined. A predictive model is recommended. (iv.) The magnitude of the potential internal phosphorus loading from the sediment upon the eventual reduction of external loading should be investigated. (v.) Downstream effects of alternative abatement strategies must be predicted

Developing State and National Evaluation Infrastructures- Guidance for the Challenges and Opportunities of EM&V

Evaluating the impacts and effectiveness of energy efficiency programs is likely to become increasingly important for state policymakers and program administrators given legislative mandates and regulatory goals and increasing reliance on energy efficiency as a resource. In this paper, we summarize three activities that the authors have conducted that highlight the expanded role of evaluation, measurement and verification (EM&V): a study that identified and analyzed challenges in improving and scaling up EM&V activities; a scoping study that identified issues involved in developing a national efficiency EM&V standard; and lessons learned from providing technical assistance on EM&V issues to states that are ramping up energy efficiency programs. The lessons learned are summarized in 13 EM&V issues that policy makers should address in each jurisdiction and which are listed and briefly described. The paper also discusses how improving the effectiveness and reliability of EM&V will require additional capacity building, better access to existing EM&V resources, new methods to address emerging issues and technologies, and perhaps foundational documents and approaches to improving the credibility and cross jurisdictional comparability of efficiency investments. Two of the potential foundational documents discussed are a national EM&V standard or resource guide and regional deemed savings and algorithm databases

Meteorological signals in primary productivity at two mountain lakes

Fluctuations in primary productivity at two subalpine lakes reveal both meteorological and biological influences. At Castle Lake, California, large-scale climate events such as the El Niño/Southern Oscillation affect total annual production and, combined with human fishing activity, modify the seasonal pattern of productivity. At Lake Tahoe, California-Nevada, local spring weather conditions modulate annual production and its seasonality by determining the depth of mixing and resulting internal nutrient load. Climatic conditions also contribute to deviations from the long-term trend in productivity by increasing the incidence of forest fires and through anomalous external nutrient loads during precipitation extremes. A 3-year cycle in productivity of as yet unknown origin has also been detected at Lake Tahoe

Impact of Summer Cattle Grazing on the Sierra Nevada Watershed: Aquatic Algae and Bacteria

Introduction. We evaluated periphytic algal and microbial communities to assess the influence of human and cattle impact on Sierra water quality. Methods. 64 sites (lakes and streams from Lake Tahoe to Sequoia National Park, California) were sampled for suspended indicator bacteria and algae following standardized procedures. The potential for nonpoint pollution was divided into three categories: cattle-grazing areas (C), recreation use areas (R), or remote wildlife areas (W). Results. Periphyton was found at 100% of C sites, 89% of R sites, but only 25% of W sites. Eleven species of periphytic algae were identified, including Zygnema, Ulothrix, Chlorella, Spirogyra, mixed Diatoms, and Cladophoria. Mean benthic algae coverage was 66% at C sites compared to 2% at W sites (P < 0.05). The prevalence of E. coli associated with periphyton was 100% at C sites, 25% of R sites, and 0% of W sites. Mean E. coli CFU/gm of algae detected was: C = 173,000, R = 700, W = 0. (P < 0.05). Analysis of neighboring water for E. coli bacteria >100 CFU/100 mL: C = 91%, R = 8%, W = 0 (P < 0.05). Conclusion. Higher periphytic algal biomass and uniform presence of periphyton-attached E. coli corresponded to watersheds exposed to summer cattle grazing. These differences suggest cattle grazing compromises water quality

Phylogeny and palaeoecology of Polyommatus blue butterflies show Beringia was a climate-regulated gateway to the New World

Transcontinental dispersals by organisms usually represent improbable events that constitute a major challenge for biogeographers. By integrating molecular phylogeny, historical biogeography and palaeoecology, we test a bold hypothesis proposed by Vladimir Nabokov regarding the origin of Neotropical Polyommatus blue butterflies, and show that Beringia has served as a biological corridor for the dispersal of these insects from Asia into the New World. We present a novel method to estimate ancestral temperature tolerances using distribution range limits of extant organisms, and find that climatic conditions in Beringia acted as a decisive filter in determining which taxa crossed into the New World during five separate invasions over the past 11 Myr. Our results reveal a marked effect of the Miocene–Pleistocene global cooling, and demonstrate that palaeoclimatic conditions left a strong signal on the ecology of present-day taxa in the New World. The phylogenetic conservatism in thermal tolerances that we have identified may permit the reconstruction of the palaeoecology of ancestral organisms, especially mobile taxa that can easily escape from hostile environments rather than adapt to them

The study design and rationale of the randomized controlled trial: translating COPD guidelines into primary care practice

Background: Chronic obstructive pulmonary disease (COPD) is a progressive, debilitating disease associated with significant clinical burden and is estimated to affect 15 million individuals in the US. Although a large number of individuals are diagnosed with COPD, many individuals still remain undiagnosed due to the slow progression of the disorder and lack of recognition of early symptoms. Not only is there under-diagnosis but there is also evidence of sub-optimal evidence-based treatment of those who have COPD. Despite the development of international COPD guidelines, many primary care physicians who care for the majority of patients with COPD are not translating this evidence into effective clinical practice. Method/Design This paper describes the design and rationale for a randomized, cluster design trial (RCT) aimed at translating the COPD evidence-based guidelines into clinical care in primary care practices. During Phase 1, a needs assessment evaluated barriers and facilitators to implementation of COPD guidelines into clinical practice through focus groups of primary care patients and providers. Using formative evaluation and feedback from focus groups, three tools were developed. These include a computerized patient activation tool (an interactive iPad with wireless data transfer to the spirometer); a web-based COPD guideline tool to be used by primary care providers as a decision support tool; and a COPD patient education toolkit to be used by the practice team. During phase II, an RCT will be performed with one year of intervention within 30 primary care practices. The effectiveness of the materials developed in Phase I are being tested in Phase II regarding physician performance of COPD guideline implementation and the improvement in the clinically relevant outcomes (appropriate diagnosis and management of COPD) compared to usual care. We will also examine the use of a patient activation tool - ‘MyLungAge’ - to prompt patients at risk for or who have COPD to request spirometry confirmation and to request support for smoking cessation if a smoker. Discussion Using a multi-modal intervention of patient activation and a technology-supported health care provider team, we are testing the effectiveness of this intervention in activating patients and improving physician performance around COPD guideline implementation. Trial registration ClinicalTrials.gov, NCT0123756

HOW THE GROWING GAP IN LIFE EXPECTANCY MAY AFFECT RETIREMENT BENEFITS AND REFORMS.

Older Americans have experienced dramatic gains in life expectancy in recent decades, but an emerging literature reveals that these gains are accumulating mostly to those at the top of the income distribution. We explore how growing inequality in life expectancy affects lifetime benefits from Social Security, Medicare, and other programs and how this phenomenon interacts with possible program reforms. We first project that life expectancy at age 50 for males in the two highest income quintiles will rise by 7 to 8 years between the 1930 and 1960 birth cohorts, but that the two lowest income quintiles will experience little to no increase over that time period. This divergence in life expectancy will cause the gap between average lifetime program benefits received by men in the highest and lowest quintiles to widen by $130,000 (in$2009) over this period. Finally we simulate the effect of Social Security reforms such as raising the normal retirement age and changing the benefit formula to see whether they mitigate or enhance the reduced progressivity resulting from the widening gap in life expectancy

Optical Detection of a Single Nuclear Spin

We propose a method to optically detect the spin state of a 31-P nucleus embedded in a 28-Si matrix. The nuclear-electron hyperfine splitting of the 31-P neutral-donor ground state can be resolved via a direct frequency discrimination measurement of the 31-P bound exciton photoluminescence using single photon detectors. The measurement time is expected to be shorter than the lifetime of the nuclear spin at 4 K and 10 T.Comment: 4 pages, 3 figure

A Phase 1 Study of TRC102, An Inhibitor of Base Excision Repair, and Pemetrexed in Patients with Advanced Solid Tumors

Introduction TRC102 potentiates the activity of cancer therapies that induce base excision repair (BER) including antimetabolite and alkylating agents. TRC102 rapidly and covalently binds to apurinic/apyrimidinic (AP) sites generated during BER, and TRC102-bound DNA causes topoisomerase II-dependent irreversible strand breaks and apoptosis. This study assessed the safety, maximum-tolerated dose (MTD), pharmacokinetics and pharmacodynamics of TRC102 alone and in combination with pemetrexed. Purpose Patients with advanced solid tumors received oral TRC102 daily for 4 days. Two weeks later, patients began standard-dose pemetrexed on day 1 in combination with oral TRC102 on days 1 to 4. The pemetrexed-TRC102 combination was repeated every 3 weeks until disease progression. Methods Twenty-eight patients were treated with TRC102 at 15, 30, 60 or 100 mg/m2/d. The MTD was exceeded at 100 mg/m2/d due to grade 3 anemia in 50 % of patients. TRC102 exposure increased in proportion to dose with a mean t1/2 of 28 h. A pharmacodynamic assay confirmed that TRC102 binds to pemetrexed-induced AP sites at all doses studied. Stable disease or better was achieved in 15 of 25 patients evaluable for response (60 %), including one patient with recurrent metastatic oropharyngeal carcinoma that expressed high levels of thymidylate synthase, who achieved a partial response and was progression free for 14 months. Conclusions When administered with pemetrexed, the maximum tolerated dose of oral TRC102 is 60 mg/m2/d for 4 days. Randomized controlled studies are planned to evaluate the clinical benefit of adding TRC102 to pemetrexed and other agents that induce BER. © 2012 Springer Science+Business Media, LLC