Geology and Geochemistry of the Ship Creek and Monashka Creek reservoirs, Southcentral Alaska

Graywacke from the Ship Creek watershed, dissolves incongruently in distilled water. The dissolution appears to follow a first-order rate law which in integrated form is: k = -2.303/t log No-Q/No where No is the concentration in ppm of Ca, Mg, Na or K in the graywacke, Q is the total quantity of these ions leached in time t(days), k is the rate constant in days-1. Experimentally derived rate constants for the dissolution of graywacke in distilled water at 5oC are log k+2CA, -4.128 day-1; log k+2Mg, -6.174 day-1; log k+Na, -5.800 day-1; and log k+K, -5.249 day-1. The above constants are for 40 to +100 mesh graywacke. A surface area correction term must be inserted in the above equation if it is applied to a different size fraction. Using the above equation and rate constants, the chemical composition of a water in contact with graywacke was calculated. With the exception of magnesium, the agreement between the calculated composition and that of Ship Creek water was good. Assuming that the groundwater in the Ship Creek watershed contacts about 1.5X104cm2 graywacke per liter, 120 to 360 days are required at 5oC to produce the concentration of ions observed in Ship Creek. Release of exchangeable H+ from the soil mat to the reservoir water will not significant1y lower the pH of the water. Leaching of heavy metals from sulfides contained in the bedrock of the two watersheds does not pose a water quality hazard. Lineaments in the bedrock at Monashka Creek may provide channels through which water may seep from the reservoir. These are not expected to pose a problem in retaining water in the reservoir, but they may result in small, new springs down grade from the reservoir.The work upon which this report is based was supported by funds provided by the United States Department of the Interior, Office of Water Resources Research and Technology, as authorized by the Water Resources Research Act of 1964, Public Law 88-379, as amended. (Project A-045-ALAS

Arsenic in the Water, Soil Bedrock, and Plants of the Ester Dome Area of Alaska

Concentrations of arsenic as large as 10 ppm (200 times the safe limit for drinking water) occur in the groundwater of a mineralized residential area near Fairbanks. Bedrock of the area contains 750 ppm As, primarily as arsenopyrite and scorodite. The oxygen-poor groundwater is enriched in As(III) and ferrous iron while the surface waters are iron free and contain less than 50 ppb As(V). Arsenic is removed from the water by coprecipitation with ferric hydroxide. Some iron-rich stream sediments contain as much as 1,400 ppm arsenic. The distribution of arsenic in the groundwater is controlled by the distribution of arsenic in the bedrock. The arsenic content of the B soil horizon over mineralized veins is about 150 ppm, while that over barren rock is 30 ppm. The vegetation over the veins is not significantly enriched in arsenic. Lettuce, radishes and tomatoes grown with arsenic-rich water (5 ppm) contain 16, 8 and 1 ppm As, respectively; these amounts are significantly greater than plants not treated with arsenic. Preliminary studies by state and federal health agencies show no detrimental effects on the health of persons drinking these arsenic-rich waters.The work upon which this publication is based was supported in part by funds provided by the Office of Water Research and Technology (Project B-037-ALAS, Agreement No. 14-34-0001-8056), U.S. Department of the Interior, Washington, D.C., as authorized by the Water Research and Development Act of 1978

Chemical Doppelgangers in GALAH DR3: the Distinguishing Power of Neutron-Capture Elements Among Milky Way Disk Stars

The observed chemical diversity of Milky Way stars places important constraints on Galactic chemical evolution and the mixing processes that operate within the interstellar medium. Recent works have found that the chemical diversity of disk stars is low. For example, the APOGEE "chemical doppelganger rate," or the rate at which random pairs of field stars appear as chemically similar as stars born together, is high, and the chemical distributions of APOGEE stars in some Galactic populations are well-described by two-dimensional models. However, limited attention has been paid to the heavy elements (Z > 30) in this context. In this work, we probe the potential for neutron-capture elements to enhance the chemical diversity of stars by determining their effect on the chemical doppelganger rate. We measure the doppelganger rate in GALAH DR3, with abundances rederived using The Cannon, and find that considering the neutron-capture elements decreases the doppelganger rate from 2.2% to 0.4%, nearly a factor of 6, for stars with -0.1 < [Fe/H] < 0.1. While chemical similarity correlates with similarity in age and dynamics, including neutron-capture elements does not appear to select stars that are more similar in these characteristics. Our results highlight that the neutron-capture elements contain information that is distinct from that of the lighter elements and thus add at least one dimension to Milky Way abundance space. This work illustrates the importance of considering the neutron-capture elements when chemically characterizing stars and motivates ongoing work to improve their atomic data and measurements in spectroscopic surveys.Comment: 23 pages, 16 figures, 1 table. Submitted to AAS Journals, comments welcome. Associated catalog of high precision, Cannon-rederived abundances for GALAH giants to be made publicly available upon acceptance and available now upon request. See Walsen et al. 2023 for a complementary, high precision, Cannon-rederived abundance catalog for GALAH solar twin

Novel critical point drying (CPD) based preparation and transmission electron microscopy (TEM) imaging of protein specific molecularly imprinted polymers (HydroMIPs)

We report the transmission electron microscopy (TEM) imaging of a hydrogel-based molecularly imprinted polymer (HydroMIP) specific to the template molecule bovine haemoglobin (BHb). A novel critical point drying based sample preparation technique was employed to prepare the molecularly imprinted polymer (MIP) samples in a manner that would facilitate the use of TEM to image the imprinted cavities, and provide an appropriate degree of both magnification and resolution to image polymer architecture in the <10 nm range. For the first time, polymer structure has been detailed that clearly displays molecularly imprinted cavities, ranging from 5-50 nm in size, that correlate (in terms of size) with the protein molecule employed as the imprinting template. The modified critical point drying sample preparation technique used may potentially play a key role in the imaging of all molecularly imprinted polymers, particularly those prepared in the aqueous phase

A Spectroscopic Survey of Faint Quasars in the SDSS Deep Stripe: I. Preliminary Results from the Co-added Catalog

In this paper we present the first results of a deep spectroscopic survey of faint quasars in the Sloan Digital Sky Survey (SDSS) Southern Survey, a deep survey carried out by repeatedly imaging a 270 deg^2 area. Quasar candidates were selected from the deep data with good completeness over 0<z<5, and 2 to 3 magnitudes fainter than the SDSS main survey. Spectroscopic follow-up was carried out on the 6.5m MMT with Hectospec. The preliminary sample of this SDSS faint quasar survey (hereafter SFQS) covers ~ 3.9 deg^2, contains 414 quasars, and reaches g=22.5. The overall selection efficiency is ~ 66% (~ 80% at g<21.5); the efficiency in the most difficult redshift range (2<z<3) is better than 40%. We use the 1/V_{a} method to derive a binned estimate of the quasar luminosity function (QLF) and model the QLF using maximum likelihood analysis. The best model fits confirm previous results showing that the QLF has steep slopes at the bright end and much flatter slopes (-1.25 at z<2.0 and -1.55 at z>2.0) at the faint end, indicating a break in the QLF slope. Using a luminosity-dependent density evolution model, we find that the quasar density at M_{g}<-22.5 peaks at z~2, which is later in cosmic time than the peak of z~2.5 found from surveys of more luminous objects. The SFQS QLF is consistent with the results of the 2dF QSO Redshift Survey, the SDSS, and the 2dF-SDSS LRG and QSO Survey, but probes fainter quasars. We plan to obtain more quasars from future observations and establish a complete faint quasar sample with more than 1000 objects over 10 deg^2.Comment: 25 pages, 13 figures, accepted for publication in A

Sunyaev Zel'dovich Effect Observations of Strong Lensing Galaxy Clusters: Probing the Over-Concentration Problem

We have measured the Sunyaev Zel'dovich (SZ) effect for a sample of ten strong lensing selected galaxy clusters using the Sunyaev Zel'dovich Array (SZA). The SZA is sensitive to structures on spatial scales of a few arcminutes, while the strong lensing mass modeling constrains the mass at small scales (typically < 30"). Combining the two provides information about the projected concentrations of the strong lensing clusters. The Einstein radii we measure are twice as large as expected given the masses inferred from SZ scaling relations. A Monte Carlo simulation indicates that a sample randomly drawn from the expected distribution would have a larger median Einstein radius than the observed clusters about 3% of the time. The implied overconcentration has been noted in previous studies with smaller samples of lensing clusters. It persists for this sample, with the caveat that this could result from a systematic effect such as if the gas fractions of the strong lensing clusters are substantially below what is expected.Comment: submitte

Mutation in erythroid specific transcription factor KLF1 causes Hereditary Spherocytosis in the Nan hemolytic anemia mouse model

KLF1 regulates definitive erythropoiesis of red blood cells by facilitating transcription through high affinity binding to CACCC elements within its erythroid specific target genes including those encoding erythrocyte membrane skeleton (EMS) proteins. Deficiencies of EMS proteins in humans lead to the hemolytic anemia Hereditary Spherocytosis (HS) which includes a subpopulation with no known genetic defect. Here we report that a mutation, E339D, in the second zinc finger domain of KLF1 is responsible for HS in the mouse model Nan. The causative nature of this mutation was verified with an allelic test cross between Nan/+ and heterozygous Klf1(+/-) knockout mice. Homology modeling predicted Nan KLF1 binds CACCC elements more tightly, suggesting that Nan KLF1 is a competitive inhibitor of wild-type KLF1. This is the first association of a KLF1 mutation with a disease state in adult mammals and also presents the possibility of being another causative gene for HS in humans