Continuous monitoring of dissolved inorganic nitrogen (DIN) transformations along the waste-vadose zone - groundwater path of an uncontrolled landfill, using multiple N-species isotopic analysis.

Landfill leachates contain a heavy load of dissolved inorganic nitrogen (DIN), posing a threat to water resources. Therefore, it is highly important to understand the processes that control its evolution (speciation, accumulation, or attenuation) during the percolation of leachates through the unsaturated zone, finally affecting the groundwater. However, tracking DIN transformations in this complex and inaccessible environment is challenging, and knowledge concerning this important topic under field conditions is scarce. The presented study used a unique monitoring system that allows sampling of repetitive samples from within the waste and the unsaturated zone. An array of 8 wells penetrating the underlying aquifer completed the spatial observation. Multiple N-species isotopic approach was applied to discern the dominating N-involving processes over the continuum - from the waste mound through the unsaturated zone and the underlying aquifer. Despite the considerable heterogeneity observed throughout the profile, the results provided a cohesive and valuable reflection of the evolution of the inorganic nitrogen pool in this highly contaminated environment. Leachates inside the waste had reducing characteristics with high accumulation of ammonium (up to 360 mg/l NH4+-N), and a distinct δ15N-NH4+ range (-3‰ to +10‰). The upper layers of the unsaturated zone underneath the landfill margins found to be aerated, promoting N oxidation which resulted in the accumulation of nitrate in the leachates (up to 490 mg/l NO3-N). Exceptionally high concentrations of nitrite (up to 126 mg/l NO2-N) were found as oxygen levels decreased in deeper sections of the vadose zone. Enrichment of δ15N-NO2- compared to δ15N-NO3- indicated the significance of autotropic nitrite reduction, controlling the DIN composition, correlated with NO2- accumulation and net DIN attenuation. The δ15N: δ18O ratio implied co-occurrence of denitrification in the leachates, even in the more oxidized sections, further contributing to N-attenuation in the unsaturated zone. In the aquifer, δ15N-NH4+ values and δ15N: δ18O ratio linked N contamination to the leachates source. The encounter with the oxidized groundwater promoted intensive nitrification. δ15N-NO2- values in the groundwater were lighter than both δ15N-NH4+ and δ15N-NO3- by 22‰ to 62‰, implying the co-occurrence of nitrification-denitrification processes. The effect of denitrification grew with decreasing dissolved oxygen (DO) levels below 0.5 mg/l towards the center of the plume, contributing to net DIN attenuation in the plume. The findings are significant for any consideration of the risk posed by DIN, as well as remediation measures, in a landfill environment and other sites with a heavy load of degrading organic matter.

Inhibition of perchlorate biodegradation by ferric and ferrous iron.

Previous observations from in-situ biological treatments in the subsurface of a perchlorate-contaminated site revealed multiple reduction processes occurring parallel to perchlorate degradation. Iron reduction was accelerated and correlated with a decline in the efficiency of the in-situ perchlorate reduction. In the current study, we examined the influence of iron forms on perchlorate reduction. A series of kinetic laboratory experiments were conducted, using an indigenous mixed perchlorate-reducing culture, enriched from the polluted soil that was undergoing bioremediation. The results show that ferrous iron was a non-competitive inhibitor with a 41% decrease in µmax for perchlorate reduction. Moreover, chlorate was accumulated in all samples treated with ferrous iron, indicating a disruption to the chlorate reduction step. Ferric iron, however, had less impact on perchlorate degradation with non-competitive inhibition reaching a 23% decrease in µmax. Scanning electron microscopy (SEM) revealed that the presence of ferrous iron in the perchlorate degradation enrichment culture initiated cell encrustation. We propose that during perchlorate reduction and the emission of oxygen from chlorite dismutation, the chemical oxidation of ferrous iron occurred near the bacteria's surface where the enzyme is located, forming an oxidized iron crust layer that can directly affect the perchlorate reduction enzymatic system.

Holistic approach for evaluation of landfill leachate pollution potential - From the waste to the aquifer.

Leachate contamination from uncontrolled landfills is a long-lasting environmental hazard that threatens groundwater resources worldwide. We developed a holistic site-characterization approach that incorporates leachate data from the waste body, unsaturated zone, and groundwater with information on landfill geomorphology and climatic conditions. An advanced vadose-zone monitoring system was used to characterize the percolation patterns and chemical properties of the leachates in the waste body and underlying unsaturated zone; a set of observation wells was used to characterize the contaminants' distribution in the groundwater. Multivariate analysis of the chemical composition overcame multiparameter complexity, and pinpointed the dominant factors controlling contaminant migration dynamics. The landfill's mound morphology, constructed with steep slopes, led to runoff generation, limited water infiltration through the waste, and enhanced infiltration of contaminated water at the landfill margins. Aerated conditions in the unsaturated zone under the margins induced leachate degradation and oxidation processes. The chemical composition of leachates under the center of the landfill remained typically anaerobic (high DOC, NH4+, Fe2+) despite the low water penetration. The limited water-percolation rates through the waste body and substantial mixing of the leachates with the oxidizing aquifer water led to almost complete degradation of the organic matter and significant nitrogen attenuation in the groundwater. Bromide release from decomposing waste served as an effective tracer for leachate distribution in the subsurface. The holistic approach implemented in this study provides robust and valuable insights into the factors that control landfill contamination potential and can be implemented in other sites with different climatic and geomorphological features.

Combined in-situ bioremediation treatment for perchlorate pollution in the vadose zone and groundwater.

Perchlorate is considered a rapidly spreading environmental pollutant. In Israel, it has been found at high concentrations in the vadose zone (up to 30,000 mg/L) and groundwater (up to 800 mg/L) underlying former industrial waste ponds. A perchlorate-reduction method that utilizes the high degradation potential of shallow soil and the high mobility of perchlorate across the deep unsaturated zone has been proposed. The combined treatment method includes recurrent pumping and application of polluted groundwater amended with an electron donor to the shallow soil layers. As a result, perchlorate is biodegraded in the upper soil, and the treated water drains through the unsaturated zone, displacing the pollutant toward the water table, where it is immediately pumped back to the surface for further treatment through a cyclic process. In the current study, the combined treatment approach was tested in a full-scale unsaturated zone (40 m), long-term (1 year) field experiment. Results showed a daily reduction in perchlorate concentration from 800 mg/L to practically zero. A total of ˜330 kg of perchlorate was reduced during the experiment. Nevertheless, competitive reduction (iron and sulfate) and soil acidification were found to be limiting factors. The study demonstrates a potentially efficient way to overcome these limitations by optimizing electron donor concentration.

Inverse relationship between reduced fatigue and severity of anemia in oncology patients treated with integrative medicine: understanding the paradox.

OBJECTIVE: To assess the impact of integrative medicine (IM) on cancer-related fatigue in patients undergoing chemotherapy for early and advanced breast and gynecological (ovarian, endometrial, and cervical) cancer. METHODS: Patients reporting significant levels of fatigue (on the Edmonton Symptom Assessment Scale (ESAS), European Organization for Research and Treatment of Cancer Quality of Life Questionnaire (EORTC QLQ-C30), or Measure Yourself Concerns and Wellbeing questionnaire (MYCAW)) were offered complementary and integrative medicine (CIM) treatments in addition to standard supportive care. Patients who did not undergo IM treatments were designated as controls. Attending at least five CIM treatments less than 30 days between each session was considered as high adherence to integrative care (AIC). RESULTS: Of 258 eligible patients reporting significant fatigue, follow-up assessment at 6 and 12 weeks was considered optimal for 120 patients in the intervention group and for 64 controls; 88 of treated patients found to be adherent to the IM intervention. At 12 weeks, ESAS (P < 0.001) and EORTC (p = 0.001) scores for fatigue improved more significantly in treated patients, with a higher percent with optimal relative dose intensity in the AIC subgroup, both at 6 weeks (P = 0.002) and at 12 weeks (P < 0.001). IM treatment was paradoxically associated with a greater decrease in hemoglobin levels at 12 weeks (P = 0.016), more so in the AIC subgroup (P = 0.024). CONCLUSION: Integrative medicine program may alleviate cancer-related fatigue in patients with breast and gynecological cancer undergoing chemotherapy.

Application of vadose-zone monitoring system for real-time characterization of leachate percolation in and under a municipal landfill.

Leachates from solid-waste landfills are considered a severe threat to groundwater quality. The fate of pollutants in the waste and underlying unsaturated zone is crucial for evaluating environmental risks and selecting a restoration strategy. In this study, a vadose-zone monitoring system (VMS) installed in a municipal landfill was used, for the first time, to continuously track leachates percolation dynamics and assess their chemical transformation across the entire thickness of the waste body (15m) and underlying unsaturated zone (16m) to the water table. Winter rains were found to quickly infiltrate through the waste and underlying vadose zone despite a clay cover that was implemented as part of a restoration and leachate-prevention strategy. Within the waste body, the flow pattern was controlled by preferential flow paths, which changed frequently. It is hypothesized that ongoing decomposition of the waste creates dynamic variations in the waste's physical structure and flow pattern. Water samples collected from the waste layer indicated the formation of highly polluted leachates. The chemical composition in the waste body showed extreme variability between sampling points with respect to DOC (407-31,464mg/L), BOD/COD ratios (0.07-0.55), Fe2+ (6.8-1154mg/L), ammonium (68-2924mg/L) and heavy metal concentrations. Environmental hot spots creating concentrated, aggressive, "acid-phase" leachates still exist in the waste more than 13years after closing the landfill. However, continuous changes in the flow pattern and moisture distribution affected the creation and decay of such environments. In the underlying sandy vadose zone, some sections repeatedly exhibited stronger and faster flow characteristics than others. These local fluxes of concentrated leachates rapidly transported heavy contaminant loads toward the groundwater. However results showed evidence of continual attenuation processes in the deep vadose zone, with the anaerobic digestion of organic matter, as well as the significant retention of heavy metals.

Seasonal and soil-type dependent emissions of nitrous oxide from irrigated desert soils amended with digested poultry manures.

Expansion of dryland agriculture requires intensive supplement of organic fertilizers to improve the fertility of nutrient-poor desert soils. The environmental impact of organic supplements in hot desert climates is not well understood. We report on seasonal emissions of nitrous oxide (N2O) from sand and loess soils, amended with limed and non-limed anaerobic digestate of poultry manure in the Israeli Negev desert. All amended soils had substantially higher N2O emissions, particularly during winter applications, compared to unammended soils. Winter emissions from amended loess (10-175mgN2Om-2day-1) were markedly higher than winter emissions from amended sand (2-7mgN2Om-2day-1). Enumeration of marker genes for nitrification and denitrification suggested that both have contributed to N2O emissions according to prevailing environmental conditions. Lime treatment of digested manure inhibited N2O emissions regardless of season or soil type, thus reducing the environmental impact of amending desert soils with manure digestate.

Using the natural biodegradation potential of shallow soils for in-situ remediation of deep vadose zone and groundwater.

In this study, we examined the ability of top soil to degrade perchlorate from infiltrating polluted groundwater under unsaturated conditions. Column experiments designed to simulate typical remediation operation of daily wetting and draining cycles of contaminated water amended with an electron donor. Covering the infiltration area with bentonite ensured anaerobic conditions. The soil remained unsaturated, and redox potential dropped to less than -200mV. Perchlorate was reduced continuously from ∼1150mg/L at the inlet to ∼300mg/L at the outlet in daily cycles. Removal efficiency was between 60 and 84%. No signs of bioclogging were observed during three operation months although occasional iron reduction observed due to excess electron donor. Changes in perchlorate reducing bacteria numbers were inferred from an increased in pcrA gene abundances from ∼105 to 107 copied per gram at the end of the experiment indicating the growth of perchlorate-reducing bacteria. We proposed that the topsoil may serve as a bioreactor to treat high concentrations of perchlorate from the contaminated groundwater. The treated water that infiltrates from the topsoil through the vadose zone could be used to flush perchlorate from the deep vadose zone into the groundwater where it is retrieved again for treatment in the topsoil.

Ammonia transformations and abundance of ammonia oxidizers in a clay soil underlying a manure pond.

Unlined manure ponds are constructed on clay soil worldwide to manage farm waste. Seepage of ammonia-rich liquor into underlying soil layers contributes to groundwater contamination by nitrate. To identify the possible processes that lead to the production of nitrate from ammonia in this oxygen-limited environment, we studied the diversity and abundance of ammonia-transforming microorganisms under an unlined manure pond. The numbers of ammonia-oxidizing bacteria and anammox bacteria were most abundant in the top of the soil profile and decreased significantly with depth (0.5 m), correlating with soil pore-water ammonia concentrations and soil ammonia concentrations, respectively. On the other hand, the numbers of ammonia-oxidizing archaea were relatively constant throughout the soil profile (10(7) amoA copies per g(soil)). Nitrite-oxidizing bacteria were detected mainly in the top 0.2 m. The results suggest that nitrate accumulation in the vadose zone under the manure pond could be the result of complete aerobic nitrification (ammonia oxidation to nitrate) and could exist as a byproduct of anammox activity. While the majority of the nitrogen was removed within the 0.5-m soil section, possibly by combined anammox and heterotrophic denitrification, a fraction of the produced nitrate leached into the groundwater.

Simultaneous counter-flow of chlorinated volatile organic compounds across the saturated-unsaturated interface region of an aquifer.

Concentrations of chlorinated volatile organic compounds (Cl-VOCs) at the saturated-unsaturated interface region (SUIR; depth of approximately 18m) of a sandy phreatic aquifer were measured in two monitoring wells located 25m apart. The concentrations of the Cl-VOCs obtained above and below the water table along a 413-day period are interpreted to depict variable, simultaneous and independent movement of trichlorothene, tetrachloroethene, 1,1-dichloroethene, cis-1,2-dichloroethene, 1,1,1-trichloroethane, chloroform and 1,1-dichloroethane vapors in opposite directions across the SUIR.

Transport of testosterone and estrogen from dairy-farm waste lagoons to groundwater.

Although concentrated animal feeding operations constantly generate physiologically active steroidal hormones, little is known of their environmental fate. Estrogen and testosterone concentrations in groundwater and their distribution in sediments below a dairy-farm wastewater lagoon were therefore determined and compared to a reference site located upgradient of the farm. Forward simulations of flow as well as estrogen and testosterone transport were conducted based on data from the sediment profile obtained during drilling of a monitoring well belowthe dairy-farm waste lagoon. Testosterone and estrogen were detected in sediments to depths of 45 and 32 m, respectively. Groundwater samples were directly impacted by the dairy farm, as evidenced by elevated concentrations of nitrate, chloride, testosterone, and estrogen as compared to the reference site. Modeling potential transport of hormones in the vadose zone via advection, dispersion, and sorption could not explain the depths at which estrogen and testosterone were found, suggesting that other transport mechanisms influence hormone transport under field conditions. These mechanisms may involve interactions between hormones and manure as well as preferential flow paths, leading to enhanced transport rates. These types of interactions should be further investigated to understand the processes regulating hormone transport in the subsurface environment and parametrized to forecast long-term fate and transport of steroidal hormones.

Dynamics of flood water infiltration and ground water recharge in hyperarid desert.

A study on flood water infiltration and ground water recharge of a shallow alluvial aquifer was conducted in the hyperarid section of the Kuiseb River, Namibia. The study site was selected to represent a typical desert ephemeral river. An instrumental setup allowed, for the first time, continuous monitoring of infiltration during a flood event through the channel bed and the entire vadose zone. The monitoring system included flexible time domain reflectometry probes that were designed to measure the temporal variation in vadose zone water content and instruments to concurrently measure the levels of flood and ground water. A sequence of five individual floods was monitored during the rainy season in early summer 2006. These newly generated data served to elucidate the dynamics of flood water infiltration. Each flood initiated an infiltration event which was expressed in wetting of the vadose zone followed by a measurable rise in the water table. The data enabled a direct calculation of the infiltration fluxes by various independent methods. The floods varied in their stages, peaks, and initial water contents. However, all floods produced very similar flux rates, suggesting that the recharge rates are less affected by the flood stages but rather controlled by flow duration and available aquifer storage under it. Large floods flood the stream channel terraces and promote the larger transmission losses. These, however, make only a negligible contribution to the recharge of the ground water. It is the flood duration within the active streambed, which may increase with flood magnitude that is important to the recharge process.

Particle transport in unsaturated fractured chalk under arid conditions.

A series of field and laboratory experiments were conducted to study the mechanisms of particle detachment and transport from fractures in vadose chalk. Experiments of intermittent flow events along fracture surfaces were carried out in the laboratory. In the field, water was percolated from land surface via a discrete fracture into a compartmental sampler installed inside a horizontal corehole located I m below the surface. The mass, size distribution, and composition of the particles drained from the fracture voids were examined along with flow rates and salt dissolution. Two boreholes penetrating the underlying saturated zone were sampled and analyzed for colloidal concentration and composition. Most of the particle and solute release at the drained effluents occurred during the first several hours of flow, but erratic pulses of particles were still observed after long periods of time. Most of the detached particles had a mean diameter of >2 microm, while the mobile colloidal phase in the groundwater had a mean diameter of approximately 1 microm. Mineralogical composition of the groundwater colloids and the particles detached from the upper vadose fracture were similar. Laboratory observations demonstrated the importance of the existence of a coating layer, made of weathered particles and salts, on particle detachment. The results of this study suggest that: (1) particle detachment causes flow-rate variability in the unsaturated fracture; (2) the mechanisms of particle detachment and salt dissolution within the fracture are linked: and (3) although most of the detached particles are large and likely to accumulate inside fractures, some colloidal particles also eroded from the fracture void and are likely to be transported to the groundwater.