Aquatic Resources Management of the Colorado River Ecosystem

The Colorado River system has often been referred to as the most regulated river system in the world. The Colorado River Basin serves millions of people through agricultural, energy, municipal and industrial uses, fish and wildlife activities, and recreation. The symposium was conceived and organized to allow researchers, private industry, consultants, water users, regulatory agencies, and concerned citizens the opportunity to express needs, desires, and concerns about the vast resources of the Colorado River. We found that there were a diverse number of problems confronting the individuals who are involved in the management of this important ecosystem. A variety of broad topics have been presented which include: water policy and major diversions; energy impacts; oil shale development--resources and impacts; Lake Mead and the other major reservoirs in the system; the ecology and management of the watershed and the riparian habitat in the system; fisheries; salinity problems; sedimentation; eutrophication; flow depletion; and water augmentation. This timely symposium brought together many individuals, representing a variety of disciplines, to discuss and transfer information appropriate to the needs of the Colorado River Basin. The results of this symposium, which have been compiled herein, are an attempt to examine current and projected effects of water and land management within the Colorado River Basin and to provide a basis for determining what can be done to better manage the resources within the total context of activities affecting the Colorado River Ecosystem

Reentrant Spin-Peierls Transition in Mg-Doped CuGeO_3

We report a synchrotron x-ray scattering study of the diluted spin-Peierls (SP) material Cu_{1-x}Mg_xGeO_3. In a recent paper we have shown that the SP dimerization attains long-range order only for x < x_c = 0.022(0.001). Here we report that the SP transition is reentrant in the vicinity of the critical concentration x_c. This is manifested by broadening of the SP dimerization superlattice peaks below the reentrance temperature, T_r, which may mean either the complete loss of the long-range SP order or the development of a short-range ordered component within the long-range ordered SP state. Marked hysteresis and very large relaxation times are found in the samples with Mg concentrations in the vicinity of x_c. The reentrant transition is likely related to the competing Neel transition which occurs at a temperature similar to T_r. We argue that impurity-induced competing interchain interactions play an essential role in these phenomena.Comment: 5 pages, 4 embedded eps figure

The Evaluation of Metals and Other Substances Released into Coal Mine Accrual Waters on the Wasatch Plateau Coal Field, Utah

Six sites on the Wasatch Plateau were chosen representing subsurface coal mines which were discharging or collecting accrual water on this coal field. Water samples were collected monthly at these sites for a period of 1 year (May 1981 to April 1982). Samples were taken before and after each mine\u27s treatment system. Water sampels were analyzed for major anions and cations, trace metals, physical properaties, nutrients, total organic carbon, oil and grease, trihalomethanes, and algal assay. Predictions were made as to the possible effects these coal mine accrual waters would have when used for drinking water, irrigation water, stock and wildlife watering, and as discharges into freshwater aquatic ecosystems. Compliance of the mine water discharges with NPDES regulations was also noted. Crushed coal samples were obtained from each of the six mine sites and evaluated with regard to their leaching characteristics in laboratory upflow leaching columns using an aqueous leaching medium characteristic of the area\u27s water supplies. Leachate samples were anlyzed for major anions and cations, trace metals, physical properaties, and total organic carbon. laboratory leaching characteristics were compared to the chemical nature of the actual mine water discharges. Mine water discharges were not found to be acidic in nature, the values for most parameters monitored during the field and laboratory portions of the study fell below the toxicity criteria for uses mentioned above, and were generally in compliance with NPDES regulations. Boron was present in the mine waters, but at levels which would be predicted to cause only minor or no damage to the most sensitive crops. The drinking water limit and the freshwater aquatic life bioaccumulation criterion for mercury were exceeded on several occasions in the coal mine accrual waters sampled. A comprehensive study of fish tissue samples and water samples taken from bodies of water near coal mines is recommended. Total suspended solids (TSS) and oil and grease were among the most frequently violated parameters with regard to NPDES regulations. Further studies are recommended with regard to the effects of these substances on stream biota, their sources and their rate in aquatic ecosystems. Coal leaching trends in the laboratory column experiments pralleled many of the trends observed in the field data collected. Trends for pH, aluminum, arsenic, beryllium, cadmium, chromium, cobalt, copper, iron, lead, molybdenum, nickel, silver, zinc, boron, lithium, strontium, alkalinity, chloride, cluoride, potassium, sodium, and silica were generally consistent when these comparisons were made. Values for water hardness parameters were observed to be specific to the mine site involved and not always comparable to laboratory leachate column data. Generalizations with respect to leaching trends and origins of chemical substances in coal mine accrual waters must be made with caution due to the great potential variability in coal samples and the complexity of leaching phenomena

Trihalomethane Compounds and Their Precursors in Salt Lake County: Evaluation of Trihalomethane Source and Production

Salt Lake County, Utah, watershed streams, drinking water treatment plants, and distribution systems were monitored for a period of one year or greater to determine the seasonal watershed precursor load, trihalomethane (THM) formation, and correlation between the two in the drinking water supplies. In addition, unit treatment processes were examined at Parleys, Big and Little Cottonwood water treatment plants, in the spring and late summer, to evaluate THM precursor reduction and THM formation. Additional studies were also conducted to appraise the potential contribution of natural sources to watershed THM precursor loading. Total organic carbon was used to estimate THM precursor concentrations. Instantaneous (time of sampling) and 7-day (incubated) forms of trihalomethanes were measured. Stream THM precursor production was greatest during spring runoff; the mean precursor concentration at this time was 3.4 mg/1. Stream discharge and precursor concentration frequently exhibited a linear correlation. high streamflow, as related to precipitation events, produced greater THM formation potential. Rainfall runoff from roads and other distrubed areas provided most of the instream precursor load. Leaf littler and surface soils near streams were shown to be potentially significant sources of THM precursors (leaf litter more than soils). THM formation at all water treatment plants peaked during March to June and September to October, corresponding to increated runoff in the spring, and precipitation, reservoir using reservoir water had greater (approximately 60 percent) mean annual effluent THM concentrations thatn those using solely stream water. THMs at all distribution stations averaged less than 40 ug/1 (greater than water treatment plants) during 1981. Groundwater had a comparatively small THM formation potential. The USEPA maximum contaminant level of 100 ug/1 was never exceeded at any utility or distribution station. The water treatment plants normally reduced the influent organic precursor concentration by about 30 percent, principally by sedimentation and filtration. Instandaneous THMs generally increased with process time. Precursor and chlorine concentrations for long term control of THM formation include sources control of surface water organics and nutrients, improving treatment plant efficiency, and minimizing chlorine dosages

Eutrophication Assessment of Mt. Dell Reservoir

The degree and possible causes of eutrophication in Mt. Dell Reservoir, a small water supply reservoir in Parleys Canyon above Salt Lake City, were examined with a number of limnological studes. These studies described external (incoming stream flow) and internal (sediment) nutrient sources, general limnology, nutrient limitations, and trophic state. A monthly program of sampling at selected stream sites determined taht one area of mixed agricultural and undistrubed rangeland contributed significant amounts of total soluble inorganic nitrogen. Sediment phosphorus uptake and release rates were determined with aquatic three-phase microcosms. The results indicated that sediment phosphorus mass loadings were small (less than 5% of the total loading) compared to stream phosphorus mass loadings if the hypolimnion is aerobic. Anoxic conditions could cause sediment phosphorus releases to be greater than stream phosphorus mass loadings (about 68% of the total). Descriptive limnologies indicated that the reservoir was alkaline (pH about 8.0 and alkalinities usually around 200 mg CaCO3.a), dimictic, weakly stratified, and usually well oxygenated. Nutrient levels were usually highest during the winter and at greater depths. Highest total phosphorus and orthophosphate levels were generally within a range of 50-100 ug/l whereas total nitrogen and total soluble inorganic nitrogen concentrations ranged from 0.1 to 2.0 mg/l. Blue-green algae were the dominant algal type comprising 80 percent of the total algal composition. Algae were most numerous and chlorophyl

An Experimental Investigation of the Effects of Crude Oil on Two Freshwater Lake Ecosystems

Responses of two freshwater lake ecosystems of the Intermountain West to crude oil impaction were investigated. The research was conducted in two phases; in the first phase effects of crude oil were studied on an ecosystem established in three phase laboratory microcosms (gaseous-aqueous-sediment), which simulated the natural lakes. Notable responses of the microcosm ecosystem to oil impaction included: an increased oxygen demand by the biological community, nutrient immobilization, a reduction in plant biomass accumulation and a heterotrophically dominated ecosystem. The increased availability of biologically degradable reduced carbon (i.e., the oil) and nutrient immobilization, rather than toxic effects of oil on plants, were the primary factors leading to a long-term imbalance between autotrophs and heterotrophs following oil addition. The second phase of the research was designed to investigate effects of crude oil on plant litter decomposition in the same two lakes. In general, crude oil reduced the rate and extent o

Reentrant Spin-Peierls Transition in Mg-Doped CuGeO_3

We report a synchrotron x-ray scattering study of the diluted spin-Peierls (SP) material Cu_{1-x}Mg_xGeO_3. In a recent paper we have shown that the SP dimerization attains long-range order only for x < x_c = 0.022(0.001). Here we report that the SP transition is reentrant in the vicinity of the critical concentration x_c. This is manifested by broadening of the SP dimerization superlattice peaks below the reentrance temperature, T_r, which may mean either the complete loss of the long-range SP order or the development of a short-range ordered component within the long-range ordered SP state. Marked hysteresis and very large relaxation times are found in the samples with Mg concentrations in the vicinity of x_c. The reentrant transition is likely related to the competing Neel transition which occurs at a temperature similar to T_r. We argue that impurity-induced competing interchain interactions play an essential role in these phenomena.Comment: 5 pages, 4 embedded eps figure

Operative and middle-term results of cardiac surgery in nonagenarians: A bridge toward routine practice

Background: Age >90 years represents in many centers an absolute contraindication to cardiac surgery. Nonagenarians are a rapidly growing subset of the population posing an expanding clinical problem. To provide helpful information in regard to this complex decision, we analyzed the operative and 5-year results of coronary and valvular surgical procedures in these patients. Methods and Results: We retrospectively reviewed 127 patients aged ≥90 years who underwent cardiac surgery within our hospital group in the period 1998 to 2008. Kaplan-Meier and multiple logistic regression analyses were performed. A longer follow-up than most published studies and the largest series published thus far are presented. Mean age was 92 years (range, 90 to 103 years). Mean logistic EuroSCORE was 21.3±6.1. Sixty patients had valvular surgery (including 11 valve repairs), 49 patients had coronary artery bypass grafting, and 18 had valvular plus coronary artery bypass grafting surgery (55 left mammary artery grafts implanted). Forty-five patients (35.4%) were operated on nonelectively. Operative mortality was 13.4% (17 cases). Fifty-four patients (42.5%) had a complicated postoperative course. There were no statistically significant differences in the rate and type of complications between patient strata on the basis of type of surgery performed. Nonelective priority predicted a complicated postoperative course. Predictors of operative mortality were nonelective priority and previous myocardial infarction. Kaplan-Meier survival estimates at 5 years were comparable between patient groups on the basis of procedure performed. Conclusions: Although the rate of postoperative complications remains high, cardiac surgery in nonagenarians can achieve functional improvement at the price of considerable operative and follow-up mortality rates. Cardiac operations in these very elderly subjects are supported if appropriate selection is made and if the operation is performed earlier and electively. Our results should contribute to the development of guidelines for cardiac operations in nonagenarians. © 2010 American Heart Association. All rights reserved

Virtual unrolling and deciphering of Herculaneum papyri by X-ray phase-contrast tomography

A collection of more than 1800 carbonized papyri, discovered in the Roman 'Villa dei Papiri' at Herculaneum is the unique classical library survived from antiquity. These papyri were charred during 79 A.D. Vesuvius eruption, a circumstance which providentially preserved them until now. This magnificent collection contains an impressive amount of treatises by Greek philosophers and, especially, Philodemus of Gadara, an Epicurean thinker of 1st century BC. We read many portions of text hidden inside carbonized Herculaneum papyri using enhanced X-ray phase-contrast tomography non-destructive technique and a new set of numerical algorithms for 'virtual-unrolling'. Our success lies in revealing the largest portion of Greek text ever detected so far inside unopened scrolls, with unprecedented spatial resolution and contrast, all without damaging these precious historical manuscripts. Parts of text have been decoded and the 'voice' of the Epicurean philosopher Philodemus is brought back again after 2000 years from Herculaneum papyri