Laboratory Column Experiments Using Polymer Mats to Remove Selected VOCs, PAHs, and Pesticides from Ground Water

Large-scale column experiments were undertaken to evaluate the potential of polymer mats to remove selected volatile organic compounds, polycyclic aromatic hydrocarbons, and pesticides (atrazine and fenamiphos) from ground water and potentially to act as permeable reactive barriers in contaminated ground water environments. The polymer mats, composed of interwoven silicone (dimethylsiloxane) tubes and purged with air, were installed in 2 m long flow-through columns. The polymer mats proved efficient in physically removing (stripping) benzene and naphthalene from contaminated water. Removal efficiencies for both these compounds from an aqueous phase flowing past a polymer mat were 75% or greater. However, for atrazine and fenamiphos, removal efficiencies were 5% or less, probably as a result of their lower Henry's law constants and possibly lower polymer diffusion coefficients.
These experiments indicate that, at least for relatively volatile compounds, polymer mats can provide a remediation technique for the removal of organic compounds from contaminated water. Application of this technique may be well suited as a longer-term, semipassive strategy to remediate contaminated ground water, using natural ground water flow to deliver contaminated ground water to polymer mats engineered as sorption-stripping barriers.
Additional benefits of this technique may include targeted delivery of gaseous chemical amendments, such as oxygen, to enhance aerobic biodegradation and to further reduce any residual concentrations of contaminants.     

Li,Sr, Mg,and Na in foraminiferal calcite shells from laboratory culture,sediment traps,and sediment cores

Constant-temperature laboratory culture experiments of the planktonic foraminiferal species Globigerinoides sacculifer (Brady) suggest that the ratios of Li and Sr to Ca in the shells are a function of these ratios in the culture solutions. $\text{Mg}\text{Ca}$ and $\text{Na}\text{Ca}$ in the shells did not vary with changes of these ratios in the culture solution. These are the first direct determinations of the relationship between foraminiferal shell chemistry and solution composition.The possibility of temperature dependence for the minor elemental composition of foraminiferal shells was also investigated in the laboratory and by analysis of several planktonic and one benthic foraminiferal species from sediment trap and sediment core samples. The $\text{Sr}\text{Ca}$, $\text{Mg}\text{Ca}$, and $\text{Na}\text{Ca}$ ratios in the natural samples roughly correlate with calcification temperature, whereas differences in the Li/Ca ratios are small and not systematically related to temperature. However, laboratory culture experiments at 20°C and 30°C showed no variation in the $\text{Li}\text{Ca}$, $\text{Sr}\text{Ca}$, $\text{Mg}\text{Ca}$, and $\text{Na}\text{Ca}$ ratios with calcification temperature for the planktonic foraminifera G. sacculifer and Orbulina universa. Therefore, observed differences in the $\text{Sr}\text{Ca}$, $\text{Mg}\text{Ca}$, and $\text{Na}\text{Ca}$ ratios for the sediment trap and core foraminiferal samples cannot be ascribed to direct effects of calcification temperature, but may be due to some other environmental factor which is correlated with temperature.     

Talc paragenesis in some siliceous dolomitic rocks,and its sedimentologic significance

Thin (0.5–4 mm), contorted stringers of talc, associated with apatite and minor pyrite, are containdy Formation in eastern Alabama. The form, position and lithologic distribed within generally saccharoidal dolomite-quartz marbles of the Cambrian Shaution of the stringers strongly suggest an algalstromatolitic origin, with interlaminar trapped dolomitic muds. Metamorphic formation of talc plus apatite proceeded only within the stringers, whereas surrounding marble remained as unreacted dolomite plus quartz. Talc generation is best explained by the reaction $${\text{dolomite}} + {\text{silica}} + {\text{water}} + {\text{P}}_{\text{2}} {\text{O}}_{\text{5}} = {\text{talc}} + {\text{apatite}} + {\text{CO}}_{\text{2}}$$ in which the phosphate was supplied to the reaction from organic matter contained within the stromatolitic layers. The system was probably open to CO₂ during metamorphism, and \(P_{{\text{CO}}_{\text{2}} }\) remained relatively low.     

Surface circulation of the Indian Ocean during the last glacial maximum, approximately 18,000 yr B.P.

A seasonal reconstruction of the Indian Ocean during the last glacial maximum (18,000 yr B.P.) reveals that its surface circulation and sea surface temperature patterns were significantly different from the modern Indian Ocean. This reconstruction is based on the planktonic foraminiferal biogeography and estimated sea surface temperatures in 42 Indian Ocean samples. Compared to modern conditions, the polar front was 5° to 10° latitude further north during the last glacial maximum; the Subtropical Convergence was 2° to 5° latitude further north. The West Australian Current was more intense as part of the West Wind Drift was deflected northward along the coast of Australia. The Agulhas Current was cooler and weaker during the summer and more saline and subtropical during the winter. In general, the low latitudes underwent little temperature change. The western Arabian Sea was warmer which implies less upwelling and a weaker Southwest Monsoon. On the average, the Indian Ocean was 1.9°C cooler in February and 1.7°C cooler in August during the last glacial maximum.     

Environmental implications of a beetle assemblage from the Gervais Formation (early Wisconsinan?), Minnesota

The Gervais Formation of northwestern Minnesota is the oldest known Quaternary stratigraphic unit in the Red River Valley. Wood from the fossiliferous silt and peat member is > 46,900 yr old. The age of the unit is uncertain but may be early Wisconsinan. A well-preserved beetle assemblage consisting of extant species is described from the fossiliferous horizon. Presently, most of the species are widely distributed and occur in Minnesota. The remainder have restricted northern distributions. Included in this group is the weevil Vitavitus thulius, known only from two localities in Northwest Territories. The sedimentary environment indicated by the beetles was a small lake, rich in aquatic and semi-aquatic vegetation. The margins were characterized by open areas and spruce woodland. Species with arctic-alpine distributions indicate a cold environment, but whether it was regional or local in extent could not be determined. If regional, a climate similar to that of the tundra-forest transition zone is postulated with mean July temperatures in the range 11° to 14°C. If the cold environment was restricted, however, the climate may have been similar to that of the Lake Superior region with a mean July temperature of 17°C.     

Spreadsheet Modeling of Slug Tests Using the van der Kamp Method

Slug testing is frequently employed to calculate aquifer transmissivity and hydraulic conductivity. The van der Kamp technique for interpreting slug test data which experience force-free water level oscillations is not routinely employed because it requires adjusting equations to match the observed well response data. This adjustment can be rapid and convenient when a commercial spreadsheet is employed.     

Vertical Contaminant Profiling of Volatile Organic* in a Deep Fractured Basalt Aquifer

Volatile organic compounds delected in ground water from wells at Test Area North (TAN) at the Idaho National Engineering Laboratory (INEL) prompted RCRA facility investigations in 1989 and 1990 and a CERCLA-driven RI/FS in 1992. In order to address ground water treatment feasibility, one of the main objectives, of the 1992 remedial investigation was to determine the vertical extent of ground water contamination, where the principle contaminant, of concern is trichloroethylene (TCE). It was hypothesized that a sedimentary interbed at depth in the fractured basalt aquifer could be inhibiting vertical migration of contaminants to lower aquifers. Due to the high cost of drilling and installation of ground water monitoring wells at this facility (greater than $100,000 per well), a real time method was proposed for obtaining and analyzing ground water samples during drilling to allow accurate placement of well screens in zones of predicted VOC contamination. This method utilized an inflatable pump packer pressure transducer system interfaced with a datalogger and PC at land surface. This arrangement allowed for real lime monitoring of hydraulic head above and below the packer to detect leakage around the packer during pumping and enabled collection of head data during pumping for estimating hydrologic properties. Analytical results were obtained in about an hour from an on-site mobile laboratory equipped with a gas chromalograplvmass spectrometer (GC/MS). With the hydrologic and analytical results in hand, a decision was made to either complete the well or continue drilling to the next test zone. In almost every case, analytical results of ground water samples taken from the newly installed wells closely replicated the water quality of ground water samples obtained through the pump packer system.     

The quaternary travertine deposits of Europe and Asia Minor

A summary is provided of the published information relating to all aspects of Quaternary travertine formation in Europe west of the Ural Mountains. The deposits have been divided into two broad groups, the meteogene travertines, which result primarily from the degassing of soil-borne aqueous CO₂, and thermogene deposits resulting from the degassing of thermally generated CO₂. Meteogene deposits are rare above latitude 58°N, and in regions where the mean annual air temperature is below 5°C. A significant positive correlation exists between mean air temperature and travertine deposit thickness. The combined effects of temperature and rainfall are used to provide a zoned map showing the travertine-forming potential of limestones within the region. Information from ¹⁴C dating indicates that deposition reached a maximum in the period 5–10 ka BP) and is currently limited by land and water management practices in the populated areas. Thermogene deposits occur in regions of high CO₂ discharge resulting from tectonic activity, such as Italy and Turkey where there is much vulcanism. These travertines are frequently more massive and less readily weathered than meteogene deposits. Fully referenced information is provided for 320 important, mostly well studied sites (227 meteogene, 93 thermogene), of which 156 are currently active.