Glyphosate in Soils: Retention, Transport, and Effect of Phosphate

Glyphosate [N-(phosphonomethyl) glycine)] (GPS) is currently the most commonly used herbicide worldwide, and is generally considered as immobile in soils. However, numerous reports of the environmental occurrence of the herbicide coupled with recent evidence of human toxicity require further investigation as to the behavior of GPS in the soil environment. The objectives of this study were to quantify GPS sorption and mobility in two Louisiana agricultural soils with varying physiochemical properties; Commerce silt loam and Sharkey clay. Results of batch sorption studies indicated a high affinity of both soils for solvated GPS, with 24-hour Freundlich partitioning coefficients of 158 and 396 L kg-1 for the Commerce and Sharkey soils, respectively. Sorption by the Commerce soil was likely facilitated by the relatively high amounts of amorphous Fe and Al oxides, whereas the high cation exchange capacity of the Sharkey soil likely allowed for complexation with surface exchangeable polyvalent cations. A two-site multi-reaction model incorporating time-dependent reversible and irreversible reactions provided an adequate description of the measured data. The results of miscible displacement studies indicated that the mobility of GPS is highly limited in both soils, with only 2-3% of the applied herbicide mass recovered in the effluent solution. Similar to the batch study, a two-site multi-reaction transport model (MRTM) consisting of kinetic reversible and irreversible reactions provided a good description of the breakthrough data from both soils, and outperformed linear modeling approaches using CXTFIT. Competitive batch experiments, where sorption of both GPS and phosphate was considered, suggested that competition between the two solutes for reactive sites in both soils is significant, with phosphate being preferentially sorbed. GPS mobility in the Commerce soil remained highly limited when applied in conjunction with and succeeding phosphate pulses. However, a phosphate pulse introduced to the column following a GPS pulse resulted in an additional 4% of the applied mass of the herbicide being recovered in a secondary breakthrough. These findings are significant, as they emphasize the importance of the timing of herbicide and fertilizer applications on the behavior and ultimate fate of GPS in soils

Modeling biliary polycyclic aromatic hydrocarbon metabolites in fish using high performance liquid chromatography with fluorescence detection, principal component analysis, and partial least-squares analysis

Polycyclic aromatic hydrocarbons (PAHs) constitute a diverse class of highly toxic, ubiquitous environmental pollutants, and are thus of high interest in environmental monitoring and regulation. In this study, biliary samples of English soles Parophrys vetulus and smallmouth bass Micropterus dolomieu from Seattle waterways, and chum salmon Onchorynchus keta from the north Pacific Ocean were analyzed by high performance liquid chromatography with fluorescence detection (HPLC-FLD) to gauge PAH exposure. Samples were profiled in three broad molecular weight categories, to capture naphthalene-like (NAPH), phenanthrene-like (PHEN), and benzo[a]pyrene-like (BAP) metabolites. While quantification was not achieved for the chum salmon, the semi-quantitative measurements of biliary PAH metabolites in English soles and smallmouth bass revealed differences in exposure between the two species. The fish also exhibited generally lower levels of BAP than NAPH and PHEN. Principal component analysis (PCA) of the bile data was able to capture differences in chromatogram profiles between all three species for each PAH metabolite group. Finally, the PAH metabolite concentrations of the smallmouth bass were modeled and predicted using partial least-squares (PLS) regression models applied to their HPLC-FLD chromatogram data. The leave-one-out cross validation models were able to make fairly accurate predictions of BAP (R2 = 0.9483) and PHEN (R2 = 0.9394) concentrations but performed slightly worse with the NAPH data (R2 = 0.8944). These results indicate the potential for automated chemometric screening of bile data to determine PAH contamination in fish

Equivariant intersection cohomology of the circle actions

In this paper, we prove that the orbit space B and the Euler class of an action of the circle S^1 on X determine both the equivariant intersection cohomology of the pseudomanifold X and its localization. We also construct a spectral sequence converging to the equivariant intersection cohomology of X whose third term is described in terms of the intersection cohomology of B.Comment: Final version as accepted in RACSAM. The final publication is available at springerlink.com; Revista de la Real Academia de Ciencias Exactas, Fisicas y Naturales. Serie A. Matematicas, 201

Low scatter and ultra-low reflectivity measured in a fused silica window

We investigate the reflectivity and optical scattering characteristics at 1064\,nm of an antireflection coated fused silica window of the type being used in the Advanced LIGO gravitational-wave detectors. Reflectivity is measured in the ultra-low range of 5-10\,ppm (by vendor) and 14-30\,ppm (by us). Using an angle-resolved scatterometer we measure the sample's Bidirectional Scattering Distribution Function (BSDF) and use this to estimate its transmitted and reflected scatter at roughly 20-40\,ppm and 1\,ppm, respectively, over the range of angles measured. We further inspect the sample's low backscatter using an imaging scatterometer, measuring an angle resolved BSDF below $10^{-6}$ sr$^{-1}$ for large angles (10$^\circ$--80$^\circ$ from incidence in the plane of the beam). We use the associated images to (partially) isolate scatter from different regions of the sample and find that scattering from the bulk fused silica is on par with backscatter from the antireflection coated optical surfaces. To confirm that the bulk scattering is caused by Rayleigh scattering, we perform a separate experiment, measuring the scattering intensity versus input polarization angle. We estimate that 0.9--1.3\,ppm of the backscatter can be accounted for by Rayleigh scattering of the bulk fused silica. These results indicate that modern antireflection coatings have low enough scatter to not limit the total backscattering of thick fused silica optics.Comment: 9 pages, 10 figure

Investing in the Future: A Case Study on Demographic Trends and the Policy Implications for Clark County School District

Clark County School District (CCSD) is the 5th largest school district in the nation. Through the use of the United States Census Bureau’s 2020 ACS 5-year survey, demographic trends will be analyzed for CCSD. This brief will focus on three demographic trends that have direct connections to educational success. Those three demographic trends are: internet access, poverty level (households on SNAP), and school enrollment. Potential policy interventions include technology device loan programs, adopting meal programs for students and their families, and new staff recruiting plans for CCSD

Assessing Competitive Reaction Rates in the Nitration of 2-Methylbiphenyl, Biphenyl, and Toluene to Determine Steric Restriction in Resonance-Stabilized Planarization of the Carbocation Intermediates

Electrophilic aromatic substitution (EAS) reactions have long been a fundamental addition to sophomore-level organic chemistry classes, allowing students the opportunity to explore the electron donating and withdrawing effects of electrons contained in the substituents of the aromatic reactant. In this paper we present preliminary findings on the nitration of methylated biphenyls using kinetic and regioselective assessments to analyze steric influences on the planarization of 2-methylbiphenyl after EAS nitration. Our preliminary findings show that nitration favors the methylated phenyl ring of 2-methylbiphenyl, indicating that the steric influence of the methyl group restricts planarization of the carbocation intermediate. Furthermore, a competition nitration reaction between biphenyl and toluene provides proof of concept for kinetic assessment of nitration rates that will eventually be applied to 2-methylbiphenyl; this competitive nitration showed that biphenyl nitrates 1.87 ± 0.61 (95% C.I.) times faster than toluene

Selection of Russian Plutonium Beryllium Sources for Inclusion in the Nuclear Mateirals Information Program Archive

Throughout the 1960s and 1970s, the former Soviet Union produced and exported Plutonium-Beryllium (PuBe) neutron sources to various Eastern European countries. The Russian sources consist of an intermetallic compound of plutonium and beryllium encapsulated in an inner welded, sealed capsule and consisting of a body and one or more covers. The amount of plutonium in the sources ranges from 0.002 g up to 15 g. A portion of the sources was originally exported to East Germany. A portion of these sources were acquired by Los Alamos National Laboratory (LANL) in the late 1990s for destruction in the Offsite Source Recovery Program. When the OSRP was canceled, the remaining 88 PuBe neutron sources were packaged and stored in a 55-gal drum at T A-55. This storage configuration is no longer acceptable for PuBe sources, and the sources must either be repackaged or disposed of. Repackaging would place the sources into Hagan container, and depending on the dose rates, some sources may be packaged individually increasing the footprint and cost of storage. In addition, each source will be subject to leak-checking every six months. Leaks have already been detected in some of the sources, and due to the age of these sources, it is likely that additional leaks may be detected over time, which will increase the overall complexity of handling and storage. Therefore, it was decided that the sources would be disposed of at the Waste Isolation Pilot Plant (WIPP) due to the cost and labor associated with continued storage at TA-55. However, the plutonium in the sources is of Russian origin and needs to be preserved for research purposes. Therefore, it is important that a representative sample of the sources retained and archived for future studies. This report describes the criteria used to obtain a representative sample of the sources. Nine Russian PuBe neutron sources have been selected out of a collection of 77 sources for inclusion in the NMIP archive. Selection criteria were developed so that the largest sources that are representative of the collection are included. One representative source was chosen for every 20 sources in the collection, and effort was made to preserve sources unique to the collection. In total, four representative sources and five unique sources were selected for the archive. The archive samples contain 40 grams of plutonium with an isotopic composition similar to that of weapon grade material and three grams of plutonium with an isotopic composition similar to that of reactor grade plutonium

Exploring Gaps in City Climate Planning in the Mountain West

This fact sheet explores data from the 2022 Brookings Institution report by Joseph W. Kane, Adie Tomer, Caroline George, and Jamal Russell Black called “Not according to plan: Exploring gaps in city climate planning and the need for regional action. The original report analyzes decarbonization plans for 50 of the largest U.S. cities and comparatively ranks each plan using a point system of 5 categories. This fact sheet focuses on Mountain West cities (Denver, CO; Phoenix, AZ; Las Vegas, NV; Salt Lake, UT; and Albuquerque, NM) included in the original study

Housing Affordability Index: Mountain West Cities, November 2021

This fact sheet highlights data on the median household income, median home price, estimated monthly mortgage and taxes, and share of income used for homeownership in fifteen Mountain West housing markets, as originally outlined in the “RealtyHop Housing Affordability Index: November 2021” report. The RealtyHop report analyzes the affordability of housing markets for the 100 most populous cities in the United States

COVID-19 and Nevada Counties: Employment Data, May 2019 and May 2021

This fact sheet displays county-level employment data and unemployment rates for 17 counties in Nevada, as reported by The Daily Yonder article “Rural Employment Grew in May, but Fewer People Are Seeking Jobs” in July 2021. Bill Bishop and Tim Marema compiled data from the U.S. Bureau of Labor Statistics (BLS) for each county in the United States for May 2019 and May 2021