As numerical models of turbulent flow in the Atmospheric Boundary Layer (ABL) improve in their temporal and spatial resolution, high-resolution remote sensing measurements become increasingly important for validation and improved understanding. The Turbulent Eddy Profiler, a recently developed UHF imaging radar, provides a tool both to observe the three dimensional structure of clear-air scattering from refractive index turbulence with fine spatial and temporal resolution and to explore the limits to this resolution. This dissertation focuses on the space-time statistics of the clear-air radar signal and their implications on measurements of winds, temperature, and spatial coherence. A theoretical analysis of the statistics of the radar echo is presented, resulting in a general expression of the space-time autocorrelation of the radar signal. This expression is later used in the analysis of wind profiling techniques, where Spaced Antennas (SA) algorithms are compared to Doppler Beam Swinging (DBS) methods. The relation between SA and DBS methods is studied, leading to the conclusion that DBS methods are better suited for use with imaging radars where beams may be electronically steered. The implementation of a TEP-based Radio Acoustic Sounding System (RASS) to retrieve temperature fields is described. Using TEP, the spatial structure of RASS echoes using a UHF radar is revealed for the first time. Three-dimensional RASS-measurements of virtual temperature are used to explicitly calculate structure functions, and to retrieve profiles of the structure function parameter of virtual temperature. The stream-wise spectral coherence of the vertical wind field in the convective boundary layer is studied using TEP data. Results are compared to theoretical curves that include the effect of volume averaging inherent to radar data, and to Large Eddy Simulation data. There is scant experimental validation of these relationships. Experimental results are found to be in good agreement with both simulations and theory under convective conditions. This promising result suggests multiple beam radars may study spatial coherence under neutral or stable conditions.

Investigations were conducted at a salt/premix storage facility lying on top of a glacial drumlin near the coastline in eastern Massachusetts, to characterize salt contaminated groundwater. Groundwater hydrogeochemical variations at different depths were determined based on ten years of monthly or quarterly water quality data from 54 monitoring wells. Groundwater was grouped in three water categories – shallow, middle and deep. Hydrogeochemical characterization indicates that the dominant water types are Na-Cl, Na-Ca-Cl and Ca-HCO 3 from the shallow to deep water group. Rock weathering is the dominant hydrogeochemical process for deep water group, whereas salt water percolation and cation exchange control chemical compositions of the shallow and middle water groups. Groundwater is classified as post-cation exchange, under-cation exchange and non-cation exchange groups. Gaseous CO2 and total dissolved inorganic carbon (TDIC) transport in unsaturated and saturated zones of the glacial drumlin was also investigated. A measurement system with non-dispersive infrared gas sensors was used to monitor the recovery of CO2 concentration in the headspace of purged monitoring wells. The transient, radial diffusion of CO2 from surrounding soil to the monitoring well is analogous to an existing slug test theory when the headspace is fully mixed. A nested Fibonacci search was performed to calibrate equilibrium soil CO2 concentration cO and soil gas porosity θS near the water table. The results demonstrate that water table wells with partially submerged screens can facilitate the equilibrium between the gaseous and dissolved phase of CO2. In the saturated zone, a new model was developed to describe the vertical transport of TDIC in the groundwater. The vertical transport was considered to be a balance of uniform vertical advection and vertical dispersion, subject to a first order source term with two boundary conditions at depth and at the water table. Fifteen years of monthly or quarterly data from 28 monitoring wells in the southern part of the site were used to calibrate a vertical dispersivity α of 5.9 cm and a first order source constant λ of 8.2 x10-9 s-1. These values suggest minimal degassing of groundwater CO2 across the water table and till deposition during Late Wisconsinan deglaciation of the region.

Surface drinking water sources are threatened with non-point fecal contamination usually originated from runoff that carries fecal material from wild and farm animals, and from leaking septic and sewerage systems. Identification of the specific source(s) of contamination would allow for more effective management and control programs in a watershed. Sorbitol-fermenting Bifidobacteria and Rhodococcus coprophilus have been suggested as bacterial indicators of fecal contamination from human and animal origin, respectively. The ecology of the bacteria was investigated. Detection and enumeration methods for the two indicators were evaluated and optimized. The effect of environmental and experimental factors in the recovery, detection levels, and false-positive/false-negative incidences were investigated. Membrane filtration, incubation on Human Bifid Sorbitol Agar, followed by confirmation tests is the recommended method for sorbitol-fermenting Bifidobacteria. Filtration-resuspension, spread-plating and incubation on MM3 agar is recommended for R. coprophilus . A survey of animal and human fecal samples confirmed the potential of sorbitol-fermenting Bifidobacteria as a human-fecal indicator and of R. coprophilus as a grazing (farm) animal fecal indicator. The detection/absence of the indicators in the water samples collected during a one-year survey around the Wachusett Reservoir and its watershed in Central Massachusetts agreed with the potential sources suggested by land use in the sampling areas. The usefulness of a typing procedure to characterize strains of R. coprophilus originated from different animals was investigated. A total of 45 strains of R. coprophilus were isolated from the fecal samples and subjected to a set of biochemical and antibiotic sensitivity tests. The resulting data was analyzed statistically in an attempt to develop a biotyping method that allows for the classification of the isolates according to their animal of origin. The method included carbohydrate utilization tests, growth on sole carbon source tests and antibiotic resistance tests. This method still needs further development, but could be used for the identification of the source(s) of R. coprophilus detected and isolated from water samples.

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Widespread contamination of ground and surface water with nitrate (NO3-) and perchlorate (ClO4 -) has been recorded in many US states. Nitrate and perchlorate are soluble anions that are known to affect human health. This dissertation presents the results of three studies of biological reduction ClO4 - and NO3- using autotrophic bacteria. In the first study, hydrogenotrophic (H2 oxidizing) denitrifiers were inoculated into two hollow fiber membrane bioreactors (HFMB), which were set up in different configurations (I and II). In Configuration I, H 2 passed through the lumen of the fibers and nitrified water flowed through the shell. In Configuration II, liquid flowed through the lumen and H2 through the shell. Complete denitrification was achieved in both systems with pH and biomass control at hydraulic retention times (HRT) of 8.3 and 1.5 hours for configurations I and II, respectively. Influent dissolved oxygen (DO) did not inhibit denitrification. The second study investigated reduction of NO3- and ClO4- in ion exchange (IX) brines using halophilic-hydrogenotrophic bacteria in a HFMB (Configuration II). Continuous operation of the HFMB resulted in partial denitrification (30%) of the brines. Batch HFMB operation resulted in average removal efficiencies of 30% and 42% for NO3- and ClO4-, respectively. The third study investigated ClO4- reduction using Sulfur Utilizing Perchlorate Reducing Bacteria (SUPeRB). SUPeRB cultures reduced 5-20 mg/L ClO4- to < 0.5 mg/L at varying salinities (0-30 g/L NaCl). Perchlorate (8-0.01 mg/L) reduction was achieved in packed bed reactors (PBR) inoculated with SUPeRB and filled with S° pellets and crushed oyster shells at empty bed contact times of 8-13 hours for low and high ClO4- concentrations, respectively. Decreased ClO4- removal efficiency was observed at increased recirculation velocity and with small S0 particle sizes. Influent DO or NO3- did not inhibit overall ClO4- removal.

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