Chemical characterization of clastic cave sediments and insights into particle transport and storage in karst aquifers

Abstract Chemical characterization of clastic cave sediments and insights into particle transport and storage in karst aquifers Jill L. Riddell Cave sediments can be divided into two groups: precipitates and clastics. Precipitates are speleothems, or lithologic or mineral features that are chemically precipitated in the cave environment. Clastic cave sediments are frequently described by depositional facies, sorting, and particle size (Bosch and White, 2004). Robust analytical chemical analyses of these sediments to quantify their physical and chemical components is rarely performed although some chemical characterization of mineralogy and paleomagnetism has become prevalent in recent years (Chess et al., 2010; Sasowsky et al., 2007). The organic carbon content of cave sediments can be representative of organic carbon concentrations in the larger karst system and concentrations of organic carbon in cave sediments can be used to estimate the potential retardation of organic contaminants through the entire karst system. The ability of karst sediments to be a sorbent for metals and organic contaminants, and store and transport contaminants is positively correlated with the amount of organic carbon in the sediment; yet these concentrations are rarely reported in karst sediments. This dissertation seeks to fill the gap in the mineralogy and chemical components of cave sediments; quantify the organic carbon content of cave sediments relative to depositional facies; and measure the adsorption of an organic microsphere onto a cave sediment to explore sediment-contaminant interactions. A case study from Dropping Lick Cave in Monroe County, WV, is presented where a variety of analytical techniques were used to determine the active fraction ( \u3c 2mm) mineralogy and chemical components of the sediment The sediments were silt and sand-sized particles consisting of quartz, some clay or silicate minerals, dolomite, and amorphous materials. The particle size and total carbon was within the same range reported for the \u3c 2mm fraction in other clastic cave sediments in this region, in the central United States, and in Puerto Rico. The preliminary mineralogy of the sediments is congruent with the mineralogy of surrounding siliciclastic rocks indicating that the source of the sediment is erosional products from nearby Peters Mountain and its slopes. Particle size, TOC, and total nitrogen were measured in sediments representing different facies in Butler Cave, Virginia, USA. TOC concentrations ranged from 0.08 – 0.87 weight percent and C:N molar ratio ranged from 3 – 15, indicating a possible terrestrial source of organic carbon in these sediments. TOC concentrations measured in Butler Cave were within the same range as those observed in above water, eogenetic clastic cave sediments from two caves in Puerto Rico. Estimated retardation factors calculated based on the TOC concentrations in the Butler Cave sediments indicate the range of TOC in this cave could be responsible for 39 – 987% increase in retardation of selected contaminants. This study highlights the importance of measuring the ranges of TOC in clastic cave sediments across different facies and their role in contaminant fate and transport. In this study, The adherence of carboxylated and nonfunctionalized polystyrene microspheres onto a clastic cave sediment was quantified for microsphere dilutions in three water types – deionized water, a 25 mg/L CaCO3 solution, and a karst spring water. Regardless of water type, both types of microspheres adhered to the sediment. Infrared absorbance data of different microsphere-solution-sediment mixtures indicated the potential presence of sediment minerals and microspheres in the solution. Analysis of solution pH and infrared spectra suggested pH and mineral constituents of the sediment are the most important factors in microsphere adherence. Using the adherence data, estimated KOC values for both types of microspheres were calculated and were in the same ranges as phthalates, a known contaminant in karst aquifers that is also considered a plastic, like polystyrene. The chemical and physical commonalities between microspheres and organic and microplastic (MP) contaminants warrant further investigation of microspheres as a proxy for contaminants in sediment-contaminant experiments. The results of these experiments suggest that consideration of MPs adhered to sediments should be considered when quantifying MP contamination in karst systems

Comparing diel cycles of dissolved inorganic carbon to diel cycles of Fe and Mn at a coal mine drainage site in Harrison Co., WV

Diel (24 hour) cycles of dissolved inorganic carbon and dissolved metals have rarely been studied in concert in coal mine drainage systems containing high CO2. Diel samples were collected from two locations at a site with elevated CO2; the locations differed in their CO 2 concentrations and the amount of vegetation present. Field data and samples were collected from both locations during March, May, and July 2014. To determine if the parameters cycled in a diel fashion, the data were fit using a cosine model and the goodness of fit was determined using an f-test statistic. Overall, 15 of 20 selected parameters could be fit using the cosine model with an f-test statistic p≤0.01. Parameters found to have diel cycling patterns were pH, temperature, dissolved oxygen, CO2, inorganic carbon, delta13CDIC, Fe(II), FeTOT, Y, Zn, K, Al, Mn, As, and Ni. More parameters had a diel behavior according to the model fit in the downstream location (which is in a wetland) and as the seasons progressed. When the same model and analysis were applied to data from other sites and studies, similar phasing was observed. Metals concentrations were approximately 200% lower at this study site than in 2007 but stronger diel cycles were present in 2007. Likely mechanisms driving diel behavior at this site are a combination of solar-activated process such as pH; temperature-controlled sorption reactions; the photosynthesis-cellular respiration cycle; degassing of CO2; and the residence time of the water. Future studies are needed to further separate and quantify these mechanisms on diel behavior as well as to investigate other possible mechanisms like hyporheic exchange and plant uptake

Working and learning across professional boundaries

This paper focuses on a context where interdisciplinarity intersects with interprofessionality: the work of children's services professionals who address the needs of children identified as vulnerable. It draws on evidence and perspectives from two disciplines - educational studies and health care - to consider the issues and challenges posed by learning and/or working across disciplinary boundaries and why these have proved so obdurate

Effect of angiotensin-converting enzyme inhibitor and angiotensin receptor blocker initiation on organ support-free days in patients hospitalized with COVID-19

IMPORTANCE Overactivation of the renin-angiotensin system (RAS) may contribute to poor clinical outcomes in patients with COVID-19. Objective To determine whether angiotensin-converting enzyme (ACE) inhibitor or angiotensin receptor blocker (ARB) initiation improves outcomes in patients hospitalized for COVID-19. DESIGN, SETTING, AND PARTICIPANTS In an ongoing, adaptive platform randomized clinical trial, 721 critically ill and 58 non–critically ill hospitalized adults were randomized to receive an RAS inhibitor or control between March 16, 2021, and February 25, 2022, at 69 sites in 7 countries (final follow-up on June 1, 2022). INTERVENTIONS Patients were randomized to receive open-label initiation of an ACE inhibitor (n = 257), ARB (n = 248), ARB in combination with DMX-200 (a chemokine receptor-2 inhibitor; n = 10), or no RAS inhibitor (control; n = 264) for up to 10 days. MAIN OUTCOMES AND MEASURES The primary outcome was organ support–free days, a composite of hospital survival and days alive without cardiovascular or respiratory organ support through 21 days. The primary analysis was a bayesian cumulative logistic model. Odds ratios (ORs) greater than 1 represent improved outcomes. RESULTS On February 25, 2022, enrollment was discontinued due to safety concerns. Among 679 critically ill patients with available primary outcome data, the median age was 56 years and 239 participants (35.2%) were women. Median (IQR) organ support–free days among critically ill patients was 10 (–1 to 16) in the ACE inhibitor group (n = 231), 8 (–1 to 17) in the ARB group (n = 217), and 12 (0 to 17) in the control group (n = 231) (median adjusted odds ratios of 0.77 [95% bayesian credible interval, 0.58-1.06] for improvement for ACE inhibitor and 0.76 [95% credible interval, 0.56-1.05] for ARB compared with control). The posterior probabilities that ACE inhibitors and ARBs worsened organ support–free days compared with control were 94.9% and 95.4%, respectively. Hospital survival occurred in 166 of 231 critically ill participants (71.9%) in the ACE inhibitor group, 152 of 217 (70.0%) in the ARB group, and 182 of 231 (78.8%) in the control group (posterior probabilities that ACE inhibitor and ARB worsened hospital survival compared with control were 95.3% and 98.1%, respectively). CONCLUSIONS AND RELEVANCE In this trial, among critically ill adults with COVID-19, initiation of an ACE inhibitor or ARB did not improve, and likely worsened, clinical outcomes. TRIAL REGISTRATION ClinicalTrials.gov Identifier: NCT0273570

Revisioning and reinvigorating a hydrogeology distinguished lecture tour through learner-engaged workshops

Abstract As geoscience and water related enrollment and degrees continue to decline, new methods are needed to recruit and engage students in these interesting and challenging interdisciplinary fields. An existing water-themed distinguished lecture tour was reinvented and reinvigorated to include a workshop to (1) promote interdisciplinary collaboration and (2) increase student engagement in earth sciences. The Geological Society of America has dedicated foundation support for a domestic and international lecture tour to promote the scientific discipline of hydrogeology. In addition to the lecture tour with a standard presentation and meetings with faculty, staff, and students, a half-day, interactive field demonstration of the inventory and assessment techniques for springs ecosystems was conducted at a spring near the lecture site. Local faculty hosts were encouraged to engage students in the planning and implementation of the demonstration workshop. The students were provided additional training to enter the interdisciplinary ecosystem data into a cloud-sourced database and to be actively engaged in producing a publication related to the springs ecosystems inventories and assessments. Of the participants of the demonstration workshops, students at eight of the host institutions became co-authors of the resulting manuscript. With the significant investment of time, resources, and logistics to implement a lecture tour, an additional interactive, hands-on, demonstration workshop is a cost-effective way to increase student engagement and provide interdisciplinary collaboration

ApoE promotes the proteolytic degradation of Abeta

Apolipoprotein E is associated with age-related risk for Alzheimer's disease and plays critical roles in Abeta homeostasis. We report that ApoE plays a role in facilitating the proteolytic clearance of soluble Abeta from the brain. The endolytic degradation of Abeta peptides within microglia by neprilysin and related enzymes is dramatically enhanced by ApoE. Similarly, Abeta degradation extracellularly by insulin-degrading enzyme is facilitated by ApoE. The capacity of ApoE to promote Abeta degradation is dependent upon the ApoE isoform and its lipidation status. The enhanced expression of lipidated ApoE, through the activation of liver X receptors, stimulates Abeta degradation. Indeed, aged Tg2576 mice treated with the LXR agonist GW3965 exhibited a dramatic reduction in brain Abeta load. GW3965 treatment also reversed contextual memory deficits. These data demonstrate a mechanism through which ApoE facilitates the clearance of Abeta from the brain and suggest that LXR agonists may represent a novel therapy for A