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This study contrasts the use of high-resolution passive sampling and traditional groundwater monitoring wells (GWMW) to characterize a chlorinated solvent site and assess the effectiveness of a biowall (mulch, compost and sand) that was installed to remediate trichloroethene (TCE), the primary contaminant of concern. High-resolution passive profilers (HRPPs) were direct driven hydraulically upgradient, within, and hydraulically downgradient of the biowall and in close proximity to existing GWMWs. Compared with hydraulically upgradient locations, the biowall was highly reducing, there were higher densities of bacteria/genes capable of reductive dechlorination, and TCE was being reductively transformed, but not completely, as cis-1,2-dichloroethene (cis-DCE) was detected within and hydraulically downgradient of the biowall. However, based on the high-resolution data, there were a number of important findings which were not discoverable using data from GWMWs alone. Data from the HRPPs indicate that the biowall was completely transforming TCE to ethene (C

Microbes are widely assumed to be capable of colonizing even the most challenging terrestrial surface environments on Earth given enough time. We would not expect to find surface soils uninhabited by microbes as soils typically harbor diverse microbial communities and viable microbes have been detected in soils exposed to even the most inhospitable conditions. However, if uninhabited soils do exist, we might expect to find them in Antarctica. We analyzed 204 ice-free soils collected from across a remote valley in the Transantarctic Mountains (84 – 85°S, 174 – 177°W) and were able to identify a potential limit of microbial habitability. While most of the soils we tested contained diverse microbial communities, with fungi being particularly ubiquitous, microbes could not be detected in many of the driest, higher elevation soils - results that were confirmed using cultivation-dependent, cultivation-independent, and metabolic assays. While we cannot confirm that this subset of soils is completely sterile and devoid of microbial life, our results do show that microbial habitability and activity can be restricted by near-continuous exposure to cold, dry, and salty conditions, establishing the environmental conditions that constrain habitability in terrestrial surface environments. Constant exposure to these conditions for thousands of years has generated uninhabited surface soil environments, with either no detectable microbes or conditions which are not suitable to sustain microbial activity. Such uninhabited soils are unlikely to be unique to the studied region with this work challenging expectations about where microbes might, or might not, be able to thrive on Earth and other planets. Significance Statement Certain surface soils in Antarctica have remained effectively uninhabited due to a near-continuous exposure to cold-dry-salty conditions. This is an unexpected result because soils, even those in hyper-arid deserts, typically contain detectable microorganisms. Additionally, the prevalence of fungi at the colder, drier, higher elevation sites suggests that certain fungi may in fact be better adapted than bacteria or archaea to some of the most challenging soil environments on Earth.

The fate and transport of groundwater contaminants depends partially on groundwater velocity, which can vary appreciably in highly stratified aquifers. A high-resolution passive profiler (HRPP) was developed to evaluate groundwater velocity, contaminant concentrations, and microbial community structure at ∼20 cm vertical depth resolution in shallow heterogeneous aquifers. The objective of this study was to use mass transfer of bromide (Br- ), a conservative tracer released from cells in the HRPP, to estimate interstitial velocity. Laboratory experiments were conducted to empirically relate velocity and the mass transfer coefficient of Br- based on the relative loss of Br- from HRPP cells. Laboratory-scale HRPPs were deployed in flow boxes containing saturated soils with differing porosities, and the mass transfer coefficient of Br- was measured at multiple interstitial velocities (0 to 100 cm/day). A two-dimensional (2D) quasi-steady-state model was used to relate velocity to mass transfer of Br- for a range of soil porosities (0.2-0.5). The laboratory data indicate that the mass transfer coefficient of Br- , which was directly-but non-linearly-related to velocity, can be determined with a single 3-week deployment of the HRPP. The mass transfer coefficient was relatively unaffected by sampler orientation, length of deployment time, or porosity. The model closely simulated the experimental results. The data suggest that the HRPP will be applicable for estimating groundwater velocity ranging from 1 to 100 cm/day in the field at a minimum depth resolution of 10 cm, depending on sampler design.

Aluminum/iodine pentoxide (Al/I2O5) composites are currently receiving much attention for their capabilities as potential anthrax combatants. Their high halogen gas release, coupled with high temperature evolution from combustion, renders them effective in bacterial deactivation. Despite extensive research on the energetic capacities of these compounds, limited information is currently available in relation to their potential environmental (non-target) effects. We evaluated the effects of Al/I2O5 on aquatic (Daphnia magna) and terrestrial (Eisenia fetida, Acheta domesticus) invertebrates, as well as alfalfa (Medicago sativa) seed germination. Polytetrafluoroethylene (PTFE, or DuPont Teflon® MP1150) was examined concurrently to assess whether observations were general to halogen, or element specific. Our observations were based on mortality and reproduction (hatchability) for the terrestrial and aquatic assays. In all Al/I2O5 assays, mortality was concentration dependent, ranging from 0% mortality in the control samples to partial and complete mortality in the contaminated cases. The PTFE assays showed no mortality at all contaminant concentrations. At a maximum Al/I2O5 contaminant concentration of 1000 μg/g (ppm), 100% mortality was observed in cricket assay conducted in sand within 72 h exposure and earthworm assay conducted in soil within 4 days exposure. In the aquatic assay, a water concentration of 200 μg/mL (ppm) caused 100% mortality to D. magna in less than 12 h. The effect of aluminum/iodine pentoxide on earthworm cocoon hatching success was also determined. At soil concentrations ≤ 400 μg/g, hatching success for earthworm cocoons was equivalent to control (un-contaminated) soil; above this concentration, hatching success was reduced by a factor of 2. Alfalfa germination tests were performed at a single contaminant concentration of 1000 μg/g. This soil concentration was completely inhibitory to seed germination.

Reverse osmosis (RO) is a treatment technology that may be used for the recovery of graywater terrestrially as well as the recovery of wastewater on board long duration, manned space flights. As with terrestrial RO applications, concentration polarization and membrane fouling lead to decreased productivity and increased energy demands with time. Physiochemical and biological pretreatment options can enhance the performance of the RO system; also, biological pretreatment has the advantages of low energy and consumable requirements as compared to other physiochemical pretreatment options. To determine the degree to which the incorporation of biological treatment enhances RO performance, a series of bench-scale experiments were performed. Observed resistances indicate that biological pretreatment alleviated the degree of non-reversible fouling while also improving the rate of permeate flux in a downstream RO process to further treat water. Results also indicated that enhanced urea hydrolysis, pH reduction, and carbon oxidation serve as the primary benefits of biological pretreatment of space-based graywater. The observations of this study may also benefit engineers considering the treatment of graywaters for terrestrial water-reuse applications.

The massive oil release from the Deep Water Horizon disaster has reemphasized the need to remediate oil impacted marshes. Due to the physically fragile nature of salt water marshes, bioremediation is often proposed as an appropriate technology and nutrient amendment is often proposed as a means of accelerating biodegradation of crude oil. However, no information is currently available concerning the efficacy of in situ nutrient amendments in Gulf Coast salt marshes. An experimental crude oil spill (142 l over 100 m2) was conducted to evaluate the efficacy of nitrogen amendment to stimulate bioremediation in a Spartina alterniflora dominated Louisiana salt marsh. A randomized complete block design with replication (n = 10) was utilized to test the hypothesis that additions of fast-release ammonium nitrate (60 g N/m2) and slow-release urea (30 g N/m2) fertilizers could enhance biodegradation of selected crude oil components in the marsh. Crude oil degradation was monitored by analyzing sediment samples for branched and unbranched alkanes over the 180-day study period. The compound/hopane ratio was used to correct for nonbiological losses. No consistent statistically significant effect of fertilizer addition on degradation rates was observed, despite success in increasing the porewater ammonium and NaCl-extractable ammonium over the time frame of the trial. Intrinsic pseudo-first order degradation rates of alkanes in all plots were substantial (0.003–0.008 day−1). Existing, background levels of N did not appear to limit biodegradation rates in Spartina-dominated salt marshes. These results suggest that nutrient amendments will not be successful in stimulation biodegradation of crude oil in these systems.

A modified membrane-aerated biofilm reactor (mMABR) that combined oxygen permeable membranes and inert attachment media to support both nitrification and denitrification was used to treat a carbon-limited (COD:N = 1.8) and ammonium-rich (NH4+ = 650 g-N/m3) space habitation waste stream. An eight-fold increase in intramembrane air pressure did not affect process performance; however, for an air pressure of 11 kPa (gauge), lower and upper hydraulic loading limits for the mMABR were identified at 30 g-N/m3 x d and 123 g-N/m3 x d, respectively. Oxygen limitation occurred at the highest loading rate and alkalinity limitation occurred at the lowest loading rate. Partial nitrification was noted at both limitations. Additionally, increased recirculation ratios were shown to decrease denitrification efficiency. Mean carbon and nitrogen removal rates were as high as 75.3 g-C/m3 x d (0.26 g-C/m2d) and 63.8 g-N/m3 x d (0.22 g-N/m2 x d), respectively. The mMABR achieved maximal nitrification and denitrification performance given the stoichiometric nature of the waste.

Recent studies have shown that natural perchlorate may be an important component to the general population exposure. These studies indicate that natural perchlorate is likely deposited by atmospheric deposition. Perchlorate concentration of total (dry + wet) deposition is relatively unstudied yet these measurements will aid in understanding natural levels in the environment. We sampled total deposition monthly at six sites in Suffolk County, Long Island, NY from November 30, 2005 until July 5, 2007. The mean perchlorate concentration is 0.21 ± 0.04 (standard error) μg L−1 with a maximum value of 2.78 μg L−1 . Here we show up to an 18-fold increase above the mean concentration in July 2006 and July 2007 samples. It appears that this increase in perchlorate in total deposition is associated with Fourth of July fireworks.

A study on perchlorate distribution was conducted in male adult prairie voles (Microtus ochrogaster). Excretion via urine was the major pathway for perchlorate fate in the body, with the highest concentrations of perchlorate detected in urine after exposure to perchlorate through drinking water [250 μg/ml Mg(ClO4)2], and an average of 34% and 88% of perchlorate intake recovered in urine in the 4- and 8-h exposure groups, respectively. Perchlorate mass in kidney, thyroid, blood, and urine were related to perchlorate intake (254.5–2687.7 μg). Perchlorate excretion and depuration patterns via urine were tested further using male adult deer mice (Peromyscus maniculatus). Animals were exposed to perchlorate through dosed drinking water (0, 17, 165, and 1600 ng/ml). Perchlorate concentrations in urine showed a significant difference among the three dosed groups during a 28-day exposure period. However, no difference was found in urine among the three dosages in terms of mass percentage of perchlorate intake from water at each sampling time over the 28-day exposure period. Both concentrations of perchlorate and mass percentage in urine reached a steady state after 1 day in all treatments. On average 46%, 46%, and 61% of perchlorate intake from water was recovered in urine over the exposure period in high, medium, and low dose groups, respectively. Including perchlorate consumption from rodent chow (1.44 ng/g), less than 46% of perchlorate intake was recovered in urine in the high and medium dose groups, and 0.99 in both the low and high dose groups; half-lives of perchlorate in deer mice were estimated as 9.12 and 7.25 h in the low and high dose groups, respectively. Endogenous generation of perchlorate and/or some degree of retention or metabolism of perchlorate may occur in deer mice, based in part on the uncompleted mass balance in the excretion and depuration experiments. The data reported herein should provide additional insight for perchlorate fate determination in animals and humans and valuable information for perchlorate risk assessment in the environment, especially wildlife.

The transit mission wastewater may represent a future graywater, in which toilet waste is separated from other household waste streams, and dilution water is minimal. A loading rate study indicated that denitrification is stoichiometrically limited, and nitrification was kinetically limited. Denitrification stoichiometry was developed by deriving hypothetical molecular formulas of organic carbon inputs to be represented by the relative proportions of carbon, hydrogen, oxygen, and nitrogen. The derived stoichiometry was validated against experimental data by adjusting the values of f e and f s and multiplying the total dissolved organic carbon loss across the system by the overall R equation and then comparing the total nitrogen removed in the reaction to experimentally observed total nitrogen removal. The nitrification stoichiometry was similarly validated by multiplying the R equation by the ammonium-nitrogen removed and then comparing the NO x -N formed in the equation to actual NO x -N production values. The f s values for the denitrifying and nitrifying bacteria were 0.33 and 0.15, respectively.

The presence of pharmaceuticals and personal care products (PPCPs) and endocrine disrupting chemicals (EDCs) in treated wastewater is gaining attention due to their potential environmental impact. An analytical method was developed to quantify estrogen compounds in samples from a concentrated wastewater matrix typical of water recycling systems used in space. The method employed conventional HPLC with UV detection. Solid phase extraction (SPE) was used to isolate the compounds of interest from wastewater. Spike-recovery tests in clean and wastewater matrices were used to test the extraction process. The results of these experiments suggest that deconjugation is the most predominant reaction occurring in the systems, as effluent concentrations of free estrogens typically exceeded influent concentrations. Despite the long retention times of the system or the near infinite solids retention time, free estrogens were not removed from graywater representative of space waste streams. For a closed-loop wastewater treatment system, these compounds may accumulate to levels requiring other removal mechanisms (i.e., reverse osmosis).

Plants can play an important role in wastewater treatment and water reuse in terrestrial and space systems. Chive growth in biologically treated graywater, simulating the anticipated early planetary base graywater, was evaluated in this study for NASA. Phytotoxicity due to physiochemical parameters such as ammonium-nitrogen (NH4 +-N), nitrite-nitrogen (NO2 −-N), pH, and sodium (Na+) was assessed using a series of hydroponic experiments in an environmentally controlled growth chamber. Nitrification in wastewater was observed in all graywater treatments, which converted NO2 −-N (a toxic form of nitrogen) and NH4 +-N (toxic at high concentrations) to nitrate-nitrogen (NO3 −-N) (preferred N form for plant uptake). Irrespective of the increase in the NO3 –-N concentration due to nitrification, chives in the wastewater treatments typically had poor or no growth. The high levels of Na+ present in the graywater treatments affected potassium uptake and may have affected other nutrient uptake. The impact of nitrification on wastewater pH and NO2 −-N toxicity is believed to be the critical factor affecting chive growth and may hinder the use high nitrogen waste streams for plant growth unless NO2 −-N concentrations are controlled during biological treatment of graywater.

The major objectives of this work were to operate and construct an autohydrogenotrophic reactor and estimate perchlorate degradation kinetics. The results show that autohydrogenotrophic bacteria were cultured in the reactor and capable of removing 3.6 mg/d of perchlorate in the presence of excess hydrogen (99% removal). The reactor was successful in treating the average influent perchlorate concentration of 532 microg/L to the level of 3 microg/L. A first-order relationship was obtained between the concentration of active biomass in the reactor and the hydraulic retention time for the given amount of substrate. During the kinetic loading study, perchlorate removal ranged from 100 to 50%. The kinetic rate of perchlorate degradation observed in this study was 1.62 hr(-1). The significant degradation of perchlorate in these samples indicates the ubiquity of perchlorate-reducing organisms. Additionally, nitrate was simultaneously removed during water treatment (greater than 90% removal). Because of the excess levels of hydrogen, simultaneous removal of nitrate was not believed to significantly affect perchlorate removal. The area of concern was the lack of complete control over biological treatment. The growth of sulfate-reducing organisms in the reactor negatively affected perchlorate removal efficiency. There were no significant effects observed on the dissolved organic carbon and total suspended solids concentration of the effluent, suggesting that the treatment did not produce a large amount of biomass washout.

The purpose of this research was to evaluate the antibiotic resistance in two water reclamation systems developed from space missions. The first system is a small-scale water reclamation system operated at Johnson Space Center designed to reclaim wastewater during long-term space missions. The second system was a scaled-down version of the Johnson Space Center system operated at Texas Tech University. Antibiotic resistance patterns to 10 antibiotics were investigated before and after controlled doses of amoxicillin were added to the water reclamation systems. The results of this study indicate that bacteria in all systems were resistant to many antibiotics including beta-lactam antibiotics and a beta-lactam, beta-lactamase inhibitor combination, amoxicillin with clavulanic acid.

Previous laboratory-scale studies have documented perchlorate ClO(-)(4) uptake by different plant species, but less information is available at field scale, where ClO(-)(4) uptake may be affected by environmental conditions, such as distance to streams or shallow water tables, exposure duration, and species. This study examined uptake of ClO(-)(4) in smartweed (Polygonum spp.) and watercress (Nasturtium spp.) as well as more than forty trees, including ash (Fraxinus greggii A. Gray), chinaberry (Melia azedarach L.), elm (Ulmus parvifolia Jacq.), willow (Salix nigra Marshall), mulberry [Broussonetia papyrifera (L.) Vent.], and hackberry (Celtis laevigata Willd.) from multiple streams surrounding a perchlorate-contaminated site. Results indicate a large potential for ClO(-)(4) accumulation in aquatic and terrestrial plants, with ClO(-)(4) concentration in plant tissues approximately 100 times higher than that in bulk water. Perchlorate accumulation in leaves of terrestrial plants was also dependent on species, with hackberry, willow, and elm having a strong potential to accumulate ClO(-)(4). Generally, trees located closer to the stream had a higher ClO(-)(4) accumulation than trees located farther away from the stream. Seasonal leaf sampling of terrestrial plants indicated that ClO(-)(4) accumulation also was affected by exposure duration, with highest accumulation observed in the late growing cycle, although leaf concentrations for a given tree were highly variable. Perchlorate may be re-released into the environment via leaching and rainfall as indicated by lower perchlorate concentrations in collected leaf litter. Information obtained from this study will be helpful to understand the fate of ClO(-)(4) in macrophytes and natural systems.

This study investigated the intrinsic perchlorate (ClO4-)degradation kinetics of sediments and soils from multiple sites in microcosm studies, including the influence of varying nitrate concentration (NO3--N from 1 to 22.8 ppm) and up to 300 ppm sulfate. The first-order degradation rates and lag times of both ClO4- and NO3- degradation were site-specific and dependent on environmental conditions such as organic substrate availability, nitrate, initial ClO4- concentration, and prior ClO4- exposure. At an initial ClO4- concentration of 5 ppm, ClO4- degradation rates ranged from 0.13 to 0.46 day-1, and lag times of ClO4- degradation ranged from 0 to 60.0 days; while NO3- degradation occurred at rates ranging from 0.03 to 1.42 day-1, with lag times ranging from 0 to 29.7 days. Under the same treatment conditions, NO3- degradation rates were relatively higher than that of ClO4-. Perchlorate degradation rates remained constant at both lower (0.5 ppm) and higher (5 ppm) ClO4- concentrations. Generally, ClO4- rates were affected by the availability of organic substrate, which was represented here by Total Volatile Solids (TVS) of sediments and soils, and not by NO3-. Nitrate did increase the lag time of ClO4- degradation, which may account for the persistence of ClO4- in the environment, especially when ClO4- is typically ppb levels in the environment compared to ppm levels of NO3-. This study showed rapid intrinsic ClO4- degradation in sediments and soils of contaminated sites, and highlighted the potential for natural attenuation of ClO4- in the environment.

Tropical salt marshes in Louisiana are at risks ofaccidental oil spills and remediation of these ecosystemsis mainly limited to natural biodegradation due tophysical sensitivity of the ecosystems. This studyinvestigated both intrinsic and nutrient enhanced ratesof crude oil degradation in core studies. In addition,loading rates of nitrogen and optimal porewater nitrogenconcentrations were determined. Nitrogen additionsincreased biodegradation rates of some alkanes andpolycyclic aromatic hydrocarbons (PAHs). Addition ofNH4+-N increased zero-order mineralizationconstants of labeled hexadecane and phenanthrene up to15.4–19.2% (Fourchon marsh) and 56.2% (Ugly Shack Bayoumarsh) and rates of total carbon dioxide production up to14.0–33.1% (Fourchon marsh) and 3.0% (Ugly Shack Bayoumarsh), respectively. Efficient biodegradation of crudeoil was achieved when NH4+ was applied at theloading rate of 28.3–56.6 g N m-2 producing porewaterconcentration at the level of 80–450 mg NH4+-N L-1. No significant lag time was observed indicating thatnitrogen application directly stimulates biodegradationof crude oil in tropical salt marshes in Louisiana.

Salt marsh ecosystems in Louisiana are at high risk of an oil contamination event while remediation of these systems is mainly limited to intrinsic bioremediation due to the physical sensitivity of salt marshes. This study investigated both the intrinsic and nutrient enhanced rates of crude oil degradation both in microcosm and core studies. In addition, limiting elements, loading rates and optimum nitrogen forms (NH 4 + or NO 3 - ) were determined. Salt marshes have relatively low intrinsic degradation rates (0–3.9% day-1) of the alkane component (C11-C44) but high rates (8–16% day-1) of degradation of the polycyclic aromatic hydrocarbon (PAH) fraction (naphthalene, C1, and C2-Naphthalene and Phenanthrene, C1, and C2-Phenanthrene). Additions of nitrogen statistically enhanced degradation of many alkanes and total PAHs while naturally present phosphorous was found to be sufficient. Nitrogen was found to be most effective if applied as NH 4 + in the range of 100-500-N mg kg-1 of soil producing a pore water range of 100-670-N mg L-1. Core studies indicate that similar trends are observed when applying fertilizers to intact portions of salt marsh.

This research was conducted to evaluate the use of biological nitrification-denitrification systems as pre-processors for recycling wastewater to potable water in support of space exploration. A packed-bed bioreactor and membrane-aerated nitrification reactor were operated in series with a 10:1 recycle ratio over varying loading rates. The dissolved organic carbon (DOC) removal exceeded 80% for all loading rates (theta = 1 to 6.8 days), while total nitrogen removal generally increased with decreasing retention time, with a maximum removal of 55%. The degree of nitrification generally declined with decreasing retention time from a high of 80% to a low of 60%. Maximum DOC and total nitrogen volumetric removal rates exceeded 1000 and 800 g/m3 x d, respectively, and maximum nitrification volumetric conversion rates exceeded 300 g/m3 x d. At low hydraulic loading rates, the system was stoichiometrically limited, while kinetic limitations dominated at high hydraulic loading rates. Incomplete nitrification occurred at high loading rates, likely as a result of the high pH and large concentrations of ammonia.

The potential of natural wetland systems to treat perchlorate-contaminated water was investigated in vertical upflow wetland columns planted with and without Bulrush (Scirpus sp.). In the absence of nitrate (NO3- -N

In the spring of 2002, the Texas Commission on Environmental Quality determined that perchlorate (ClO4 � ) was present in ground water from the McMillan and Paul Davis well fields that supply potable water for the city of Midland. Researchers began a large-scale sampling program to determine the source(s) and distribution of perchlorate in the area’s ground water. This document summarizes the findings of a large-scale investigation in nine counties carried out from July to December 2002. This program included public water system (PWS) wells and private wells in Andrews, Borden, Dawson, Ector, Gaines, Glasscock, Howard, Martin, and Midland counties, which occupy a total area of 23,960 km 2 . Water samples were tested for perchlorate and a suite of common ions. From a total of 254 wells sampled in the nine counties, 179 wells (70%) had detectable perchlorate concentrations (>0.5 ppb) and 88 wells (35%) had perchlorate concentrations equal to or above 4 ppb. The highest perchlorate concentration found at a private well was 58.8 ppb in Dawson County, while the highest concentration detected for a well in PWS was 45.6 ppb in city of Midland, Midland County. Perchlorate positively correlated (a < 0.0001) with Cl � ,F � ,B r � ,S O4 2� ,M g 2+ , and K + but not with NO2 � ,N O3 � , Na + ,o r Ca 2+ . Research to date has identified the most likely sources to be (1) a natural mineralogical impurity; (2) agricultural fertilizers containing perchlorate; (3) in situ generation of perchlorate by electrochemical reactions; or (4) some combination of the three. This study suggests that there may be significant sources other than the traditional industrial processing of perchlorate, and the distribution of perchlorate in ground water is likely more widespread than previously suspected.