Trace Element Contamination from Fly Ash Sites Near Chisholm Creek, VA

The safe disposal of fly ash from power plants remains a concern because of dwindling available disposal sites and potential or actual environmental consequences. During the period from 1957 to 1974, the Virginia Electric and Power Co. station at Yorktown used a mixture of coal and refinery coke for power generation. The fly ash and bottom ash byproducts were disposed of in borrow pits which drain into Chisman Creek, a small estuary near the York River. In 1980 a domestic well near the pits turned green and tests revealed high concentrations of V and Se in some wells. Subsequently, contaminated wells were capped and homes were connected to the municipal water supply. In late 1981 with a small.grant from the Virginia Environmental Endowment, we began a more detailed investigation of possible contamination from the pits. The sampling program included groundwater, surface water, estuarine water, flyash, soils near the pits, oysters and a variety of plants in the immediate vicinity. Most importantly, these samples were analyzed by PIXE (Proton-Induced X-Ray Emission), a sensitive and accurate multielemental technique which can simultaneously detect all elements from silicon to uranium without prior knowledge of the elements present.https://scholarworks.wm.edu/vimsbooks/1157/thumbnail.jp

The annual course of precipitation over much of the United States: observed versus GCM simulation

General Circulation Models (GCMs) may be useful in estimating the ecological impacts of global climatic change. We analyzed seasonal weather patterns over the conterminous United States and determined that regional patterns of rainfall seasonality appear to control the distributions of the Nation's major biomes. These regional patterns were compared to the output from three GCMs for validation. The models appear to simulate the appropriate seasonal climates in the northern tier of states. However, the spatial extent of these regions is distorted. None of the models accurately portrayed rainfall seasonalities in the southern tier of states, where biomes are primarily influenced by the Bermuda High

Development of an in vitro cytotoxicity model for aerosol exposure using 3D reconstructed human airway tissue; application for assessment of e-cigarette aerosol

AbstractDevelopment of physiologically relevant test methods to analyse potential irritant effects to the respiratory tract caused by e-cigarette aerosols is required. This paper reports the method development and optimisation of an acute in vitro MTT cytotoxicity assay using human 3D reconstructed airway tissues and an aerosol exposure system. The EpiAirway™ tissue is a highly differentiated in vitro human airway culture derived from primary human tracheal/bronchial epithelial cells grown at the air–liquid interface, which can be exposed to aerosols generated by the VITROCELL® smoking robot. Method development was supported by understanding the compatibility of these tissues within the VITROCELL® system, in terms of airflow (L/min), vacuum rate (mL/min) and exposure time. Dosimetry tools (QCM) were used to measure deposited mass, to confirm the provision of e-cigarette aerosol to the tissues. EpiAirway™ tissues were exposed to cigarette smoke and aerosol generated from two commercial e-cigarettes for up to 6h. Cigarette smoke reduced cell viability in a time dependent manner to 12% at 6h. E-cigarette aerosol showed no such decrease in cell viability and displayed similar results to that of the untreated air controls. Applicability of the EpiAirway™ model and exposure system was demonstrated, showing little cytotoxicity from e-cigarette aerosol and different aerosol formulations when compared directly with reference cigarette smoke, over the same exposure time

The nature and extent of trace element contamination associated with fly-ash disposal sites in the Chisman Creek Watershed

This study was conducted by the Virginia Institute of Marine Science (VIMS) and the Virginia Associated Research Campus (VARC), both branches of the College of William and Mary, to document the nature, extent, and severity of environmental contamination by trace elements from the landfill disposal of fly-ash within the Chisman Creek watershed. Previous work in the area demonstrated that some metals were apparently mobile in the groundwater, and that two nearby household wells were contaminated (Va. SWCB, 1981). These short term studies were limited to the testing of only a few selected contaminants in wells near the fly-ash pits. The goal of our study was to provide a more comprehensive sampling of the basin to delineate the geographical extent of trace element contamination, and to assess whether the levels found there pose a hazard to man or to the terrestrial and aquatic ecosystem. An important aspect of the program is the use of an analytical technique which provides simultaneous measurement of a large number of elements, thereby obviating the need to speculate which elements would be found before the field work was begun. Proton Induced X-ray Emission (PIXE) is such a technique and provided data on 70 elements from each sample collected during this study

Active Layer Groundwater Flow: The Interrelated Effects of Stratigraphy, Thaw, and Topography

The external drivers and internal controls of groundwater flow in the thawed “active layer” above permafrost are poorly constrained because they are dynamic and spatially variable. Understanding these controls is critical because groundwater can supply solutes such as dissolved organic matter to surface water bodies. We calculated steady‐state three‐dimensional suprapermafrost groundwater flow through the active layer using measurements of aquifer geometry, saturated thickness, and hydraulic properties collected from two major landscape types over time within a first‐order Arctic watershed. The depth position and thickness of the saturated zone is the dominant control of groundwater flow variability between sites and during different times of year. The effect of water table depth on groundwater flow dwarfs the effect of thaw depth. In landscapes with low land‐surface slopes (2–4%), a combination of higher water tables and thicker, permeable peat deposits cause relatively constant groundwater flows between the early and late thawed seasons. Landscapes with larger land‐surface slopes (4–10%) have both deeper water tables and thinner peat deposits; here the commonly observed permeability decrease with depth is more pronounced than in flatter areas, and groundwater flows decrease significantly between early and late summer as the water table drops. Groundwater flows are also affected by microtopographic features that retain groundwater that could otherwise be released as the active layer deepens. The dominant sources of groundwater, and thus dissolved organic matter, are likely wet, flatter regions with thick organic layers. This finding informs fluid flow and solute transport dynamics for the present and future Arctic.Plain Language SummaryGroundwater flow in permafrost watersheds is potentially a key component of global carbon budgets because permafrost soil stores vast amounts of carbon that could be mobilized due to a warming climate and the corresponding increase in soil thaw. In addition to carrying carbon, groundwater can supply important nutrients and solutes to surface waters. However, we do not yet understand the factors that control groundwater flow in soils above permafrost because saturation changes rapidly and continuously, and soil hydraulic properties are largely unknown. We created measurement‐informed calculations of groundwater flow from areas of permafrost with different characteristics and found that soil types, which vary based on the slope of the land surface, are the most important control. Near‐surface soils were identical in hillslopes and valleys, whereas deeper soils in hillslopes allowed for less groundwater flow than in valleys. In early summer, when only the near‐surface soils were thawed, groundwater flows in the hillslopes and valley were similar. In late summer, when the deeper soil was thawed, groundwater flow in the valley remained high, but flow in the hillslope was negligible. Our observations also showed that small mounds on the land surface caused groundwater to be trapped behind underground ice dams.Key PointsDetailed measurements of hydraulic head, hydraulic conductivity, and saturated thicknesses in active layers were made over time and spaceThree main soil layers consistently comprise the stratigraphy of the active layer across the studied Arctic watershedGroundwater flow depends most on the depth of the water table and the subsurface stratigraphy, which varies based on landscape typePeer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/151862/1/wrcr24085_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/151862/2/wrcr24085.pd

Active Layer Groundwater Flow: The Interrelated Effects of Stratigraphy, Thaw, and Topography

The external drivers and internal controls of groundwater flow in the thawed “active layer” above permafrost are poorly constrained because they are dynamic and spatially variable. Understanding these controls is critical because groundwater can supply solutes such as dissolved organic matter to surface water bodies. We calculated steady‐state three‐dimensional suprapermafrost groundwater flow through the active layer using measurements of aquifer geometry, saturated thickness, and hydraulic properties collected from two major landscape types over time within a first‐order Arctic watershed. The depth position and thickness of the saturated zone is the dominant control of groundwater flow variability between sites and during different times of year. The effect of water table depth on groundwater flow dwarfs the effect of thaw depth. In landscapes with low land‐surface slopes (2–4%), a combination of higher water tables and thicker, permeable peat deposits cause relatively constant groundwater flows between the early and late thawed seasons. Landscapes with larger land‐surface slopes (4–10%) have both deeper water tables and thinner peat deposits; here the commonly observed permeability decrease with depth is more pronounced than in flatter areas, and groundwater flows decrease significantly between early and late summer as the water table drops. Groundwater flows are also affected by microtopographic features that retain groundwater that could otherwise be released as the active layer deepens. The dominant sources of groundwater, and thus dissolved organic matter, are likely wet, flatter regions with thick organic layers. This finding informs fluid flow and solute transport dynamics for the present and future Arctic

Measurement of interfacial tension of immiscible liquid pairs in microgravity

A discussion is given of a containerless microgravity experiment aimed at measuring the interfacial tension of immiscible liquid pairs using a compound drop rotation method. The reasons for the failure to execute such experiments in microgravity are described. Also, the results of post-flight analyses used to confirm our arguments are presented

Transcriptional Networks in Epithelial-Mesenchymal Transition

Epithelial-mesenchymal transition (EMT) changes polarized epithelial cells into migratory phenotypes associated with loss of cell-cell adhesion molecules and cytoskeletal rearrangements. This form of plasticity is seen in mesodermal development, fibroblast formation, and cancer metastasis.Here we identify prominent transcriptional networks active during three time points of this transitional process, as epithelial cells become fibroblasts. DNA microarray in cultured epithelia undergoing EMT, validated in vivo, were used to detect various patterns of gene expression. In particular, the promoter sequences of differentially expressed genes and their transcription factors were analyzed to identify potential binding sites and partners. The four most frequent cis-regulatory elements (CREs) in up-regulated genes were SRY, FTS-1, Evi-1, and GC-Box, and RNA inhibition of the four transcription factors, Atf2, Klf10, Sox11, and SP1, most frequently binding these CREs, establish their importance in the initiation and propagation of EMT. Oligonucleotides that block the most frequent CREs restrain EMT at early and intermediate stages through apoptosis of the cells.Our results identify new transcriptional interactions with high frequency CREs that modulate the stability of cellular plasticity, and may serve as targets for modulating these transitional states in fibroblasts