Developing VTM-51 into an ASTM test method.

DOT National Transportation Integrated Search

1993-01-01

In 1980, the Virginia Transportation Research Council developed a procedure to test silt fence installations (VTM-51). The test determines the filtering efficiency (amount of soil removed) and the flow rate of a geotextile. A known concentration and ...

Site suitability for riverbed filtration system in Tanah Merah, Kelantan-A physical model study for turbidity removal

NASA Astrophysics Data System (ADS)

Ghani, Mastura; Adlan, Mohd Nordin; Kamal, Nurul Hana Mokhtar; Aziz, Hamidi Abdul

2017-10-01

A laboratory physical model study on riverbed filtration (RBeF) was conducted to investigate site suitability of soil from Tanah Merah, Kelantan for RBeF. Soil samples were collected and transported to the Geotechnical Engineering Laboratory, Universiti Sains Malaysia for sieve analysis and hydraulic conductivity tests. A physical model was fabricated with gravel packs laid at the bottom of it to cover the screen and then soil sample were placed above gravel pack for 30 cm depth. River water samples from Lubok Buntar, Kedah were used to simulate the effectiveness of RBeF for turbidity removal. Turbidity readings were tested at the inlet and outlet of the filter with specified flow rate. Results from soil characterization show that the soil samples were classified as poorly graded sand with hydraulic conductivity ranged from 7.95 x 10-3 to 6.61 x 10-2 cm/s. Turbidity removal ranged from 44.91% - 92.75% based on the turbidity of water samples before filtration in the range of 33.1-161 NTU. The turbidity of water samples after RBeF could be enhanced up to 2.53 NTU. River water samples with higher turbidity of more than 160 NTU could only reach 50% or less removal by the physical model. Flow rates of the RBeF were in the range of 0.11-1.61 L/min while flow rates at the inlet were set up between 2-4 L/min. Based on the result of soil classification, Tanah Merah site is suitable for RBeF whereas result from physical model study suggested that 30 cm depth of filter media is not sufficient to be used if river water turbidity is higher.

Methods for in situ Mesocosm Water Table Manipulation in Amazon Peatlands

NASA Astrophysics Data System (ADS)

Sarno, B. G.; Guardia, J. R.; Torres, M. G.; Lopez, J. G.; Rios, M. L.; Saquiray, L. M.; Rodriguez, T. C.; Rivera, P. V.; Van Haren, J. L. M.; Cadillo-Quiroz, H.

2016-12-01

Rainfall manipulation in tropical Amazon rainforests has previously been used to analyze the effects of rapidly changing drought and flood seasons on canopy dynamics, above-ground ecological function and greenhouse gas cycles. We chose to focus on variance below the rootline due to the greater carbon mass and impact of this region and the variables affecting it. We designed and implemented a system that manipulates above and below ground water exposure to control soil saturation. Isolation of soil sample was collected using a PVC pipe submerged 50 cm into the ground with an overhead watershed and an underground water filter. Similarly, a control sample of the above ground water was collected. Above ground water control was performed, not unlike previous systems, using overhead cover, drainage and rerouting, constructed using 1 inch PVC sections configured to allow 25% shed, 50% shed, and 75% increase. Underground filters were designed using variable clay concentrations to achieve desired permeability and flow rate. We selected kiln-fire pure clay discs, instead of poly-acrylamide discs, to enable a steady flow of 0.83 mL/hr. In addition, we adjusted the concentration of the clay disc with sand buffering and carbon lacing at different mass concentrations to allow direct controls of the flow rate, as high as 12.45 mL/hr. Using pure clay concentrations of 100%, 75%, and 50% by mass, and lacing the filters with carbon fill of 10%, 20%, and 30% by volume, before kiln firing, allows much more desirable flow rates. These significant increases in flow rate allow for better control of both above and below ground water exposure. Such a system will enable a more complete geochemical and microbiological analysis of soil and water within this highly variable region of the rain forest. Construction and installation of the submerged towers has been performed at numerous sites along the Peruvian Amazon River basin. Monitoring soil respiration will be performed on the current installations on a continuous schedule for 6 months, in efforts to understand the effects of water table control on the microbial community respiration and greenhouse gases production in the tropical rainforest peatlands. Our work will allow for a more complete understanding of variation in greenhouse gas sources and the ecological carbon cycle due to water table change.

Effects of fluorine on crops, soil exoenzyme activities, and earthworms in terrestrial ecosystems.

PubMed

Chae, Yooeun; Kim, Dokyung; An, Youn-Joo

2018-04-30

Fluorine can flow into the environment after leakage or spill accidents and these excessive amounts can cause adverse effects on terrestrial ecosystems. Using three media (filter paper, soil, and filter-paper-on-soil), we investigated the toxic effects of fluorine on the germination and growth of crops (barley, mung bean, sorghum, and wheat), on the activities of soil exoenzymes (acid phosphatase, arylsulfatase, fluorescein diacetate hydrolase, and urease) and on the survival, abnormality, and cytotoxicity of Eisenia andrei earthworms. The germination and growth of crops were affected by fluorine as exposure concentration increased. The activities of the four enzymes after 0-, 3-, 10-, and 20-day periods varied as exposure concentration increased. According to in vivo and in vitro earthworm assays, E. andrei mortality, abnormality, and cytotoxicity increased with increasing fluorine concentration. Overall, fluorine significantly affected each tested species in the concentration ranges used in this study. The activities of soil exoenzymes were also affected by soil fluorine concentration, although in an inconsistent manner. Albeit the abnormally high concentrations of fluorine in soil compared to that observed under natural conditions, its toxicity was much restrained possibly due to the adsorption of fluorine on soil particles and its combination with soil cations. Copyright © 2017 Elsevier Inc. All rights reserved.

Sea Salt Aerosol, Atmospheric Radon and Meteorological Observations in the Western South Atlantic Ocean (February 1981).

DTIC Science & Technology

1983-09-28

approximately isokinetic sampling conditions. The blower motor for the hi-vol was separated from the filter holder unit by a one- meter length of flexible...bridge bulkhead about 15 m above sea level and within 3 meters of the ARCAS inlet. The flow rate through the 20 cm x 25 cm glass fiber filters was...materials, atmospheric pressure, soil moisture and vegetative cover (Larson and Bressan, 1980). Radon concentrations measured a few meters above

Handling the unknown soil hydraulic parameters in data assimilation for unsaturated flow problems

NASA Astrophysics Data System (ADS)

Lange, Natascha; Erdal, Daniel; Neuweiler, Insa

2017-04-01

Model predictions of flow in the unsaturated zone require the soil hydraulic parameters. However, these parameters cannot be determined easily in applications, in particular if observations are indirect and cover only a small range of possible states. Correlation of parameters or their correlation in the range of states that are observed is a problem, as different parameter combinations may reproduce approximately the same measured water content. In field campaigns this problem can be helped by adding more measurement devices. Often, observation networks are designed to feed models for long term prediction purposes (i.e. for weather forecasting). A popular way of making predictions with such kind of observations are data assimilation methods, like the ensemble Kalman filter (Evensen, 1994). These methods can be used for parameter estimation if the unknown parameters are included in the state vector and updated along with the model states. Given the difficulties related to estimation of the soil hydraulic parameters in general, it is questionable, though, whether these methods can really be used for parameter estimation under natural conditions. Therefore, we investigate the ability of the ensemble Kalman filter to estimate the soil hydraulic parameters. We use synthetic identical twin-experiments to guarantee full knowledge of the model and the true parameters. We use the van Genuchten model to describe the soil water retention and relative permeability functions. This model is unfortunately prone to the above mentioned pseudo-correlations of parameters. Therefore, we also test the simpler Russo Gardner model, which is less affected by that problem, in our experiments. The total number of unknown parameters is varied by considering different layers of soil. Besides, we study the influence of the parameter updates on the water content predictions. We test different iterative filter approaches and compare different observation strategies for parameter identification. Considering heterogeneous soils, we discuss the representativeness of different observation types to be used for the assimilation. G. Evensen. Sequential data assimilation with a nonlinear quasi-geostrophic model using Monte Carlo methods to forecast error statistics. Journal of Geophysical Research: Oceans, 99(C5):10143-10162, 1994

Extracellular enzyme activity in a willow sewage treatment system.

PubMed

Brzezinska, Maria Swiontek; Lalke-Porczyk, Elżbieta; Kalwasińska, Agnieszka

2012-12-01

This paper presents the results of studies on the activity of extra-cellular enzymes in soil-willow vegetation filter soil which is used in the post-treatment of household sewage in an onsite wastewater treatment system located in central Poland. Wastewater is discharged from the detached house by gravity into the onsite wastewater treatment system. It flows through a connecting pipe into a single-chamber septic tank and is directed by the connecting pipe to a control well to be further channelled in the soil-willow filter by means of a subsurface leaching system. Soil samples for the studies were collected from two depths of 5 cm and 1 m from three plots: close to the wastewater inflow, at mid-length of the plot and close to its terminal part. Soil samples were collected from May to October 2009. The activity of the extra-cellular enzymes was assayed by the fluorometric method using 4-methylumbelliferyl and 7-amido-4-methylcoumarin substrate. The ranking of potential activity of the assayed enzymes was the same at 5 cm and 1 m soil depths, i.e. esterase > phosphmomoesterase > leucine-aminopeptidase > β-glucosidase > α-glucosidase. The highest values of enzymatic activity were recorded in the surface layer of the soil at the wastewater inflow and decreased with increasing distance from that point.

Kalman filters for assimilating near-surface observations into the Richards equation - Part 1: Retrieving state profiles with linear and nonlinear numerical schemes

NASA Astrophysics Data System (ADS)

Chirico, G. B.; Medina, H.; Romano, N.

2014-07-01

This paper examines the potential of different algorithms, based on the Kalman filtering approach, for assimilating near-surface observations into a one-dimensional Richards equation governing soil water flow in soil. Our specific objectives are: (i) to compare the efficiency of different Kalman filter algorithms in retrieving matric pressure head profiles when they are implemented with different numerical schemes of the Richards equation; (ii) to evaluate the performance of these algorithms when nonlinearities arise from the nonlinearity of the observation equation, i.e. when surface soil water content observations are assimilated to retrieve matric pressure head values. The study is based on a synthetic simulation of an evaporation process from a homogeneous soil column. Our first objective is achieved by implementing a Standard Kalman Filter (SKF) algorithm with both an explicit finite difference scheme (EX) and a Crank-Nicolson (CN) linear finite difference scheme of the Richards equation. The Unscented (UKF) and Ensemble Kalman Filters (EnKF) are applied to handle the nonlinearity of a backward Euler finite difference scheme. To accomplish the second objective, an analogous framework is applied, with the exception of replacing SKF with the Extended Kalman Filter (EKF) in combination with a CN numerical scheme, so as to handle the nonlinearity of the observation equation. While the EX scheme is computationally too inefficient to be implemented in an operational assimilation scheme, the retrieval algorithm implemented with a CN scheme is found to be computationally more feasible and accurate than those implemented with the backward Euler scheme, at least for the examined one-dimensional problem. The UKF appears to be as feasible as the EnKF when one has to handle nonlinear numerical schemes or additional nonlinearities arising from the observation equation, at least for systems of small dimensionality as the one examined in this study.

Development of a New Design Procedure for Overland Flow System.

DTIC Science & Technology

1982-06-18

reactor kinetics, a concept familiar to most environmental engi- neers. In the case of overland flow, the reactor is the soil surface where various physical...site during the entire study. Perforated plastic pipe was used to distri- bute wastewater along the top of each section, and a bed of crushed stone...particulate BOD. The soluble BOD is oxidized by microorganisms which are probably similar to the attached biomass found in trickling filters. However, some

Impact of rainfall intensity on the transport of two herbicides in undisturbed grassed filter strip soil cores

NASA Astrophysics Data System (ADS)

Pot, V.; Šimůnek, J.; Benoit, P.; Coquet, Y.; Yra, A.; Martínez-Cordón, M.-J.

2005-12-01

Two series of displacement experiments with isoproturon and metribuzin herbicides were performed on two undisturbed grassed filter strip soil cores, under unsaturated steady-state flow conditions. Several rainfall intensities (0.070, 0.147, 0.161, 0.308 and 0.326 cm h - 1 ) were used. A water tracer (bromide) was simultaneously injected in each displacement experiment. A descriptive analysis of experimental breakthrough curves of bromide and herbicides combined with a modeling analysis showed an impact of rainfall intensity on the solute transport. Two contrasting physical non-equilibrium transport processes occurred. Multiple (three) porosity domains contributed to flow at the highest rainfall intensities, including preferential flow through macropore pathways. Macropores were not active any longer at intermediate and lowest velocities, and the observed preferential transport was described using dual-porosity-type models with a zero or low flow in the matrix domain. Chemical non-equilibrium transport of herbicides was found at all rainfall intensities. Significantly higher estimated values of degradation rate parameters as compared to batch data were correlated with the degree of non-equilibrium sorption. Experimental breakthrough curves were analyzed using different physical and chemical equilibrium and non-equilibrium transport models: convective-dispersive model (CDE), dual-porosity model (MIM), dual-permeability model (DP), triple-porosity, dual permeability model (DP-MIM); each combined with both chemical instantaneous and kinetic sorption.

Regional Evapotranspiration Estimation by Using Wireless Sap Flow and Soil Moisture Measurement Systems

NASA Astrophysics Data System (ADS)

Kuo, C.; Yu, P.; Yang, T.; Davis, T. W.; Liang, X.; Tseng, C.; Cheng, C.

2011-12-01

The objective of this study proposed herein is to estimate regional evapotranspiration via sap flow and soil moisture measurements associated with wireless sensor network in the field. Evapotranspiration is one of the important factors in water balance computation. Pan evaporation collected from the meteorological station can only be accounted as a single-point scale measurement rather than the water loss of the entire region. Thus, we need a multiple-site measurement for understanding the regional evapotranspiration. Applying sap flow method with self-made probes, we could calculate transpiration. Soil moisture measurement was used to monitor the daily soil moisture variety for evaporation. Sap flow and soil moisture measurements in multiple sites are integrated by using wireless sensor network (WSN). Then, the measurement results of each site were scaled up and combined into the regional evapotranspiration. This study used thermal dissipation method to measure sap flow in trees to represent the plant transpiration. Sap flow was measured by using the self-made sap probes which needed to be calibrated before setting up at the observation field. Regional transpiration was scaled up through the Leaf Area Index (LAI). The LAI of regional scale was from the MODIS image calculated at 1km X 1km grid size. The soil moistures collected from areas outside the distributing area of tree roots and tree canopy were used to represent the evaporation. The observation was undertaken to collect soil moisture variety from five different soil depths of 10, 20, 30, 40 and 50 cm respectively. The regional evaporation can be estimated by averaging the variation of soil moisture from each site within the region. The result data measured by both sap flow and soil moisture measurements of each site were collected through the wireless sensor network. The WSN performs the functions of P2P and mesh networking. That can collect data in multiple locations simultaneously and has less power consumption. WSN is the best way for collecting sap flow and soil moisture data in this study. Since the data were collected through the radio in the field, there may have some noise randomly. The weighted least-squares method was used to filter the raw data. Through collecting the observation data by WSN and transferring them into regional scale, we could get regional evapotranspiration.

3D soil water nowcasting using electromagnetic conductivity imaging and the ensemble Kalman filter

NASA Astrophysics Data System (ADS)

Huang, Jingyi; McBratney, Alex; Minasny, Budiman; Triantafilis, John

2017-04-01

Mapping and immediate forecasting of soil water content (θ) and its movement can be challenging. Although apparent electrical conductivity (ECa) measured by electromagnetic induction has been used, it is difficult to apply it along a transect or across a field. Across a 3.95-ha field with varying soil texture, an ensemble Kalman filter (EnFK) was used to monitor and nowcast θ dynamics in 2-d and 3-d over 16 days. The EnKF combined a physical model fitted with θ measured by soil moisture sensors and an Artificial Neural Network model comprising estimate of true electrical conductivity (σ) generated by inversions of DUALEM-421S ECa data. Results showed that the spatio-temporal variation in θ can be successfully modelled using the EnKF (Lin's concordance = 0.89). Soil water dried fast at the beginning of the irrigation and decreased with time and soil depth, which were consistent with the classical soil drying theory and experiments. It was also found that the soil dried fast in the loamy and duplex soils across the field, which was attributable to deep drainage and preferential flows. It was concluded that the EnKF approach can be used to better the irrigation practice so that variation in irrigation is minimised and irrigation efficiency is improved by applying variable rates of irrigation across the field. In addition, soil water status can be nowcasted using this method with weather forecast information, which will provide guidance to farmers for real-time irrigation management.

Integrating retention soil filters into urban hydrologic models - Relevant processes and important parameters

NASA Astrophysics Data System (ADS)

Bachmann-Machnik, Anna; Meyer, Daniel; Waldhoff, Axel; Fuchs, Stephan; Dittmer, Ulrich

2018-04-01

Retention Soil Filters (RSFs), a form of vertical flow constructed wetlands specifically designed for combined sewer overflow (CSO) treatment, have proven to be an effective tool to mitigate negative impacts of CSOs on receiving water bodies. Long-term hydrologic simulations are used to predict the emissions from urban drainage systems during planning of stormwater management measures. So far no universally accepted model for RSF simulation exists. When simulating hydraulics and water quality in RSFs, an appropriate level of detail must be chosen for reasonable balancing between model complexity and model handling, considering the model input's level of uncertainty. The most crucial parameters determining the resultant uncertainties of the integrated sewer system and filter bed model were identified by evaluating a virtual drainage system with a Retention Soil Filter for CSO treatment. To determine reasonable parameter ranges for RSF simulations, data of 207 events from six full-scale RSF plants in Germany were analyzed. Data evaluation shows that even though different plants with varying loading and operation modes were examined, a simple model is sufficient to assess relevant suspended solids (SS), chemical oxygen demand (COD) and NH4 emissions from RSFs. Two conceptual RSF models with different degrees of complexity were assessed. These models were developed based on evaluation of data from full scale RSF plants and column experiments. Incorporated model processes are ammonium adsorption in the filter layer and degradation during subsequent dry weather period, filtration of SS and particulate COD (XCOD) to a constant background concentration and removal of solute COD (SCOD) by a constant removal rate during filter passage as well as sedimentation of SS and XCOD in the filter overflow. XCOD, SS and ammonium loads as well as ammonium concentration peaks are discharged primarily via RSF overflow not passing through the filter bed. Uncertainties of the integrated simulation of the sewer system and RSF model mainly originate from the model parameters of the hydrologic sewer system model.

Experimental results and mathematical modelling of an autotrophic and heterotrophic biofilm in a sand filter treating landfill leachate and municipal wastewater.

PubMed

Wichern, Marc; Lindenblatt, Claus; Lübken, Manfred; Horn, Harald

2008-08-01

A better understanding of wastewater treatment with soil filters is important to optimise plant operation and reduce the risk of clogging. The article presents results of a treatment concept which uses a combination of SBR and vertical-flow sand filter technology. The SBR was mainly used for denitrification and sedimentation of substances in particulate form. Efficient nitrification was achieved by the planted sand filter. Degradation rates of 10gNH(4)-N/(m(2)xd) were measured for periods with peak loadings. The two-dimensional dynamic model reproduces the biofilm growth and decay of heterotrophic and autotrophic biomass. It is capable of describing the clogging of the sand filter by combining a biochemical and a geometric model. After calibration, the model was used for the calculation of maximum nitrogen degradation performances. Maximum degradation rates of 12gNH(4)-N/(m(2)xd) can be achieved if the COD/TKN ratio is reduced before to a level lower than that of municipal wastewater. The COD was further degraded in the filter than we expected comparing it with activated sludge plants. Within the soil filter a biofilm thickness of up to 110microm is simulated depending on the embankment of gravel and grains of sand. Sensitivity analysis of model parameters showed the high impact of the maximum autotrophic growth rate, the autotrophic yield, the diffusion coefficient for oxygen and the number of contact points of the single grains of sand.

Hydroponic root mats for wastewater treatment-a review.

PubMed

Chen, Zhongbing; Cuervo, Diego Paredes; Müller, Jochen A; Wiessner, Arndt; Köser, Heinz; Vymazal, Jan; Kästner, Matthias; Kuschk, Peter

2016-08-01

Hydroponic root mats (HRMs) are ecotechnological wastewater treatment systems where aquatic vegetation forms buoyant filters by their dense interwoven roots and rhizomes, sometimes supported by rafts or other floating materials. A preferential hydraulic flow is created in the water zone between the plant root mat and the bottom of the treatment system. When the mat touches the bottom of the water body, such systems can also function as HRM filter; i.e. the hydraulic flow passes directly through the root zone. HRMs have been used for the treatment of various types of polluted water, including domestic wastewater; agricultural effluents; and polluted river, lake, stormwater and groundwater and even acid mine drainage. This article provides an overview on the concept of applying floating HRM and non-floating HRM filters for wastewater treatment. Exemplary performance data are presented, and the advantages and disadvantages of this technology are discussed in comparison to those of ponds, free-floating plant and soil-based constructed wetlands. Finally, suggestions are provided on the preferred scope of application of HRMs.

3D soil water nowcasting using electromagnetic conductivity imaging and the ensemble Kalman filter

NASA Astrophysics Data System (ADS)

Huang, Jingyi; McBratney, Alex B.; Minasny, Budiman; Triantafilis, John

2017-06-01

Mapping and immediate forecasting of soil water content (θ) and its movement can be challenging. Although inversion of apparent electrical conductivity (ECa) measured by electromagnetic induction to calculate depth-specific electrical conductivity (σ) has been used, it is difficult to apply it across a field. In this paper we use a calibration established along a transect, across a 3.94-ha field with varying soil texture, using an ensemble Kalman filter (EnKF) to monitor and nowcast the 3-dimensional θ dynamics on 16 separate days over a period of 38 days. The EnKF combined a physical model fitted with θ measured by soil moisture sensors and an Artificial Neural Network model comprising σ generated by quasi-3d inversions of DUALEM-421S ECa data. Results showed that the distribution of θ was controlled by soil texture, topography, and vegetation. Soil water dried fastest at the beginning after the initial irrigation event and decreased with time and soil depth, which was consistent with classical soil drying theory and experiments. It was also found that the soil dried fastest in the loamy and duplex soils present in the field, which was attributable to deep drainage and preferential flow. It was concluded that the EnKF approach can be used to improve the irrigation efficiency by applying variable irrigation rates across the field. In addition, soil water status can be nowcasted across large spatial extents using this method with weather forecast information, which will provide guidance to farmers for real-time irrigation management.

Field wind tunnel testing of two silt loam soils on the North American Central High Plains

NASA Astrophysics Data System (ADS)

Scott Van Pelt, R.; Baddock, Matthew C.; Zobeck, Ted M.; Schlegel, Alan J.; Vigil, Merle F.; Acosta-Martinez, Veronica

2013-09-01

Wind erosion is a soil degrading process that threatens agricultural sustainability and environmental quality globally. Protecting the soil surface with cover crops and plant residues, practices common in no-till and reduced tillage cropping systems, are highly effective methods for shielding the soil surface from the erosive forces of wind and have been credited with beneficial increases of chemical and physical soil properties including soil organic matter, water holding capacity, and wet aggregate stability. Recently, advances in biofuel technology have made crop residues valuable feed stocks for ethanol production. Relatively little is known about cropping systems effects on intrinsic soil erodibility, the ability of the soil without a protective cover to resist the erosive force of wind. We tested the bare, uniformly disturbed, surface of long-term tillage and crop rotation research plots containing silt loam soils in western Kansas and eastern Colorado with a portable field wind tunnel. Total Suspended Particulate (TSP) were measured using glass fiber filters and respirable dust, PM10 and PM2.5, were measured using optical particle counters sampling the flow to the filters. The results were highly variable and TSP emission rates varied from less than 0.5 mg m-2 s-1 to greater than 16.1 mg m-2 s-1 but all the results indicated that cropping system history had no effect on intrinsic erodibility or dust emissions from the soil surfaces. We conclude that prior best management practices will not protect the soil from the erosive forces of wind if the protective mantle of crop residues is removed.

Regional variation of flow duration curves in the eastern United States: Process-based analyses of the interaction between climate and landscape properties

NASA Astrophysics Data System (ADS)

Chouaib, Wafa; Caldwell, Peter V.; Alila, Younes

2018-04-01

This paper advances the physical understanding of the flow duration curve (FDC) regional variation. It provides a process-based analysis of the interaction between climate and landscape properties to explain disparities in FDC shapes. We used (i) long term measured flow and precipitation data over 73 catchments from the eastern US. (ii) We calibrated the Sacramento model (SAC-SMA) to simulate soil moisture and flow components FDCs. The catchments classification based on storm characteristics pointed to the effect of catchments landscape properties on the precipitation variability and consequently on the FDC shapes. The landscape properties effect was pronounce such that low value of the slope of FDC (SFDC)-hinting at limited flow variability-were present in regions of high precipitation variability. Whereas, in regions with low precipitation variability the SFDCs were of larger values. The topographic index distribution, at the catchment scale, indicated that saturation excess overland flow mitigated the flow variability under conditions of low elevations with large soil moisture storage capacity and high infiltration rates. The SFDCs increased due to the predominant subsurface stormflow in catchments at high elevations with limited soil moisture storage capacity and low infiltration rates. Our analyses also highlighted the major role of soil infiltration rates on the FDC despite the impact of the predominant runoff generation mechanism and catchment elevation. In conditions of slow infiltration rates in soils of large moisture storage capacity (at low elevations) and predominant saturation excess, the SFDCs were of larger values. On the other hand, the SFDCs decreased in catchments of prevalent subsurface stormflow and poorly drained soils of small soil moisture storage capacity. The analysis of the flow components FDCs demonstrated that the interflow contribution to the response was the higher in catchments with large value of slope of the FDC. The surface flow FDC was the most affected by the precipitation as it tracked the precipitation duration curve (PDC). In catchments with low SFDCs, this became less applicable as surface flow FDC diverged from PDC at the upper tail (> 40% of the flow percentile). The interflow and baseflow FDCs illustrated most the filtering effect on the precipitation. The process understanding we achieved in this study is key for flow simulation and assessment in addition to future works focusing on process-based FDC predictions.

Transport of oxytetracycline, chlortetracycline, and ivermectin in surface runoff from irrigated pasture.

PubMed

Bair, Daniel A; Popova, Ina E; Tate, Kenneth W; Parikh, Sanjai J

2017-09-02

The transport of oxytetracycline, chlortetracycline, and ivermectin from manure was assessed via surface runoff on irrigated pasture. Surface runoff plots in the Sierra Foothills of Northern California were used to evaluate the effects of irrigation water application rates, pharmaceutical application conditions, vegetative cover, and vegetative filter strip length on the pharmaceutical discharge in surface runoff. Experiments were designed to permit the maximum potential transport of pharmaceuticals to surface runoff water, which included pre-irrigation to saturate soil, trimming grass where manure was applied, and laying a continuous manure strip perpendicular to the flow of water. However, due to high sorption of the pharmaceuticals to manure and soil, less than 0.1% of applied pharmaceuticals were detected in runoff water. Results demonstrated an increase of pharmaceutical transport in surface runoff with increased pharmaceutical concentration in manure, the concentration of pharmaceuticals in runoff water remained constant with increased irrigation flow rate, and no appreciable decrease in pharmaceutical runoff was produced with the vegetative filter strip length increased from 30.5 to 91.5 cm. Most of the applied pharmaceuticals were retained in the manure or within the upper 5 cm of soil directly beneath the manure application sites. As this study evaluated conditions for high transport potential, the data suggest that the risk for significant chlortetracycline, oxytetracycline, and ivermectin transport to surface water from cattle manure on irrigated pasture is low.

Behaviour of radiocaesium in coastal rivers of the Fukushima Prefecture (Japan) during conditions of low flow and low turbidity--Insight on the possible role of small particles and detrital organic compounds.

PubMed

Eyrolle-Boyer, Frédérique; Boyer, Patrick; Garcia-Sanchez, Laurent; Métivier, Jean-Michel; Onda, Yuichi; De Vismes, Anne; Cagnat, Xavier; Boulet, Béatrice; Cossonnet, Catherine

2016-01-01

To investigate riverine transfers from contaminated soils of the Fukushima Prefecture in Japan to the marine environment, suspended sediments, filtered water, sediments and detrital organic macro debris deposited onto river beds were collected in November 2013 within small coastal rivers during conditions of low flow rates and low turbidity. River waters were directly filtered on the field and high efficiency well-type Ge detectors were used to analyse radiocaesium concentrations in very small quantities of suspended particles and filtered water (a few mg to a few g). For such base-flow conditions, our results show that the watersheds studied present similar hydro-sedimentary behaviours at their outlets and that the exports of dissolved and particulate radiocaesium are comparable. Moreover, the contribution of these rivers to the instantaneous export of radiocaesium to the ocean is similar to that of the Abukuma River. Our preliminary results indicate that, in the estuaries, radiocaesium concentrations in suspended sediments would be reduced by more than 80%, while radiocaesium concentration in filtered waters would be maintained. Significant correlations between radiocaesium concentrations and radiocaesium inventories in the soils of the catchments indicate that there was at that time little intra and inter-watershed variability in the transfer processes of radiocaesium from lands to rivers at this regional scale. The apparent liquid-solid partition coefficient (KD) values acquired for the lowest loads/finest particles complement the values acquired by using sediment traps and highlight the strong capacity of the smallest particles to transfer radiocaesium. Finally, but not least, our observations suggest that there could be a significant transfer of highly contaminated detrital biomass from forest litter to the downstream rivers in a rather conservative way. Copyright © 2015 Elsevier Ltd. All rights reserved.

Water Drainage from Unsaturated Soils in a Centrifuge Permeameter

NASA Astrophysics Data System (ADS)

Ornelas, G.; McCartney, J.; Zhang, M.

2013-12-01

This study involves an analysis of water drainage from an initially saturated silt layer in a centrifuge permeameter to evaluate the hydraulic properties of the soil layer in unsaturated conditions up to the point where the water phase becomes discontinuous. These properties include the soil water retention curve (SWRC) and the hydraulic conductivity function (HCF). The hydraulic properties of unsaturated silt are used in soil-atmosphere interaction models that take into account the role of infiltration and evaporation of water from soils due to atmospheric interaction. These models are often applied in slope stability analyses, landfill cover design, aquifer recharge analyses, and agricultural engineering. The hydraulic properties are also relevant to recent research concerning geothermal heating and cooling, as they can be used to assess the insulating effects of soil around underground heat exchangers. This study employs a high-speed geotechnical centrifuge to increase the self-weight of a compacted silt specimen atop a filter plate. Under a centrifuge acceleration of N times earth's gravity, the concept of geometric similitude indicates that the water flow process in a small-scale soil layer will be similar to those in a soil layer in the field that is N times thicker. The centrifuge acceleration also results in an increase in the hydraulic gradient across the silt specimen, which causes water to flow out of the pores following Darcy's law. The drainage test was performed until the rate of liquid water flow out of the soil layer slowed to a negligible level, which corresponds to the transition point at which further water flow can only occur due to water vapor diffusion following Fick's law. The data from the drainage test in the centrifuge were used to determine the SWRC and HCF at different depths in the silt specimen, which compared well with similar properties defined using other laboratory tests. The transition point at which liquid water flow stopped (and Darcy's law is no longer valid) was at a relatively high degree of saturation of 0.8. This finding is important as many water flow analyses in the literature assume that Darcy's law is valid over a much wider range of degrees of saturation, an error that potentially may lead to overestimates of water flow in unsaturated soil layers.

Towards a bias-free filter routine to determine precipitation and evapotranspiration from high precision lysimeter measurements

NASA Astrophysics Data System (ADS)

Peters, Ande; Durner, Wolfgang; Schrader, Frederik; Groh, Jannis; Pütz, Thomas

2017-04-01

Weighing lysimeters are known to be the best means for a precise and unbiased measurement of water fluxes at the interface between the soil-plant system and the atmosphere. The measured data need to be filtered to separate evapotranspiration (ET) and precipitation (P) from noise. Such filter routines apply typically two steps: (i) a low pass filter, like moving average, which is used to smooth noisy data, and (ii) a threshold filter to separate significant from insignificant mass changes. Recent developments of these filters have revealed and solved many problems regarding bias in the data processing. A remaining problem is that each change in flow direction is accompanied with a systematic flow underestimation due to the threshold scheme. In this contribution we show and analyze this systematic effect and propose a heuristic solution by introducing a so-called snap routine. The routine is calibrated and tested with synthetic flux data and applied to real data from a precision lysimeter for a 10-month period. We show that the absolute systematic effect is independent of the magnitude of a certain flux event. Thus, for small events, like dew or rime formation, the relative error is highest and can be in the same order of magnitude as the flux itself. The heuristic snap routine effectively overcomes these problems and yields an almost unbiased representation of the real signal.

Characterisation of microbial biocoenosis in vertical subsurface flow constructed wetlands.

PubMed

Tietz, Alexandra; Kirschner, Alexander; Langergraber, Günter; Sleytr, Kirsten; Haberl, Raimund

2007-07-15

In this study a quantitative description of the microbial biocoenosis in subsurface vertical flow constructed wetlands fed with municipal wastewater was carried out. Three different methods (substrate induced respiration, ATP measurement and fumigation-extraction) were applied to measure the microbial biomass at different depths of planted and unplanted systems. Additionally, bacterial biomass was determined by epifluorescence microscopy and productivity was measured via (14)C leucine incorporation into bacterial biomass. All methods showed that >50% of microbial biomass and bacterial activity could be found in the first cm and about 95% in the first 10 cm of the filter layer. Bacterial biomass in the first 10 cm of the filter body accounted only for 16-19% of the total microbial biomass. Whether fungi or methodical uncertainties are mainly responsible for the difference between microbial and bacterial biomass remains to be examined. A comparison between the purification performance of planted and unplanted pilot-scale subsurface vertical flow constructed wetlands (PSCWs) showed no significant difference with the exception of the reduction of enterococci. The microbial biomass in all depths of the filter body was also not different in planted and unplanted systems. Compared with data from soils the microbial biomass in the PSCWs was high, although the specific surface area of the used sandy filter material available for biofilm growth was lower, especially in the beginning of the set-up of the PSCWs, due to missing clay and silt fraction.

Survey monitoring results on the reduction of micropollutants, bacteria, bacteriophages and TSS in retention soil filters.

PubMed

Tondera, Katharina; Koenen, Stefan; Pinnekamp, Johannes

2013-01-01

A main source of surface water pollution in Western Europe stems from combined sewer overflow. One of the few technologies available to reduce this pollution is the retention soil filter. In this research project, we evaluated the cleaning efficiency of retention soil filters measuring the concentration ratio of standard wastewater parameters and bacteria according to factors limiting efficiency, such as long dry phases or phases of long-lasting retention. Furthermore, we conducted an initial investigation on how well retention soil filters reduce certain micropollutants on large-scale plants. There was little precipitation during the 1-year sampling phase, which led to fewer samples than expected. Nevertheless, we could verify how efficiently retention soil filters clean total suspended solids. Our results show that retention soil filters are not only able to eliminate bacteria, but also to retain some of the micropollutants investigated here. As the filters were able to reduce diclofenac, bisphenol A and metoprolol by a median rate of almost 75%, we think that further investigations should be made into the reduction processes in the filter. At this point, a higher accuracy in the results could be achieved by conducting bench-scale experiments.

Filter Membrane Effects on Water-Extractable Phosphorus Concentrations from Soil.

PubMed

Norby, Jessica; Strawn, Daniel; Brooks, Erin

2018-03-01

To accurately assess P concentrations in soil extracts, standard laboratory practices for monitoring P concentrations are needed. Water-extractable P is a common analytical test to determine P availability for leaching from soils, and it is used to determine best management practices. Most P analytical tests require filtration through a filter membrane with 0.45-μm pore size to distinguish between particulate and dissolved P species. However, filter membrane type is rarely specified in method protocols, and many different types of membranes are available. In this study, three common filter membrane materials (polyether sulfone, nylon, and nitrocellulose), all with 0.45-μm pore sizes, were tested for analytical differences in total P concentrations and dissolved reactive P (DRP) concentrations in water extracts from six soils sampled from two regions. Three of the extracts from the six soil samples had different total P concentrations for all three membrane types. The other three soil extracts had significantly different total P results from at least one filter membrane type. Total P concentration differences were as great as 35%. The DRP concentrations in the extracts were dependent on filter type in five of the six soil types. Results from this research show that filter membrane type is an important parameter that affects concentrations of total P and DRP from soil extracts. Thus, membrane type should be specified in soil extraction protocols. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

Comparison of different filter methods for data assimilation in the unsaturated zone

NASA Astrophysics Data System (ADS)

Lange, Natascha; Berkhahn, Simon; Erdal, Daniel; Neuweiler, Insa

2016-04-01

The unsaturated zone is an important compartment, which plays a role for the division of terrestrial water fluxes into surface runoff, groundwater recharge and evapotranspiration. For data assimilation in coupled systems it is therefore important to have a good representation of the unsaturated zone in the model. Flow processes in the unsaturated zone have all the typical features of flow in porous media: Processes can have long memory and as observations are scarce, hydraulic model parameters cannot be determined easily. However, they are important for the quality of model predictions. On top of that, the established flow models are highly non-linear. For these reasons, the use of the popular Ensemble Kalman filter as a data assimilation method to estimate state and parameters in unsaturated zone models could be questioned. With respect to the long process memory in the subsurface, it has been suggested that iterative filters and smoothers may be more suitable for parameter estimation in unsaturated media. We test the performance of different iterative filters and smoothers for data assimilation with a focus on parameter updates in the unsaturated zone. In particular we compare the Iterative Ensemble Kalman Filter and Smoother as introduced by Bocquet and Sakov (2013) as well as the Confirming Ensemble Kalman Filter and the modified Restart Ensemble Kalman Filter proposed by Song et al. (2014) to the original Ensemble Kalman Filter (Evensen, 2009). This is done with simple test cases generated numerically. We consider also test examples with layering structure, as a layering structure is often found in natural soils. We assume that observations are water content, obtained from TDR probes or other observation methods sampling relatively small volumes. Particularly in larger data assimilation frameworks, a reasonable balance between computational effort and quality of results has to be found. Therefore, we compare computational costs of the different methods as well as the quality of open loop model predictions and the estimated parameters. Bocquet, M. and P. Sakov, 2013: Joint state and parameter estimation with an iterative ensemble Kalman smoother, Nonlinear Processes in Geophysics 20(5): 803-818. Evensen, G., 2009: Data assimilation: The ensemble Kalman filter. Springer Science & Business Media. Song, X.H., L.S. Shi, M. Ye, J.Z. Yang and I.M. Navon, 2014: Numerical comparison of iterative ensemble Kalman filters for unsaturated flow inverse modeling. Vadose Zone Journal 13(2), 10.2136/vzj2013.05.0083.

Use of dust fall filters as passive samplers for metal concentrations in air for communities near contaminated mine tailings

PubMed Central

Beamer, P.I.; Sugeng, A. J.; Kelly, M.D.; Lothrop, N.; Klimecki, W.; Wilkinson, S.T.; Loh, M.

2014-01-01

Mine tailings are a source of metal exposures in many rural communities. Multiple air samples are necessary to assess the extent of exposures and factors contributing to these exposures. However, air sampling equipment is costly and requires trained personnel to obtain measurements, limiting the number of samples that can be collected. Simple, low-cost methods are needed to allow for increased sample collection. The objective of our study was to assess if dust fall filters can serve as passive air samplers and be used to characterize potential exposures in a community near contaminated mine tailings. We placed filters in cylinders, concurrently with active indoor air samplers, in 10 occupied homes. We calculated an estimated flow rate by dividing the mass on each dust fall filter by the bulk air concentration and the sampling duration. The mean estimated flow rate for dust fall filters was significantly different during sampling periods with precipitation. The estimated flow rate was used to estimate metal concentration in the air of these homes, as well as in 31 additional homes in another rural community impacted by contaminated mine tailings. The estimated air concentrations had a significant linear association with the measured air concentrations for beryllium, manganese and arsenic (p<0.05), whose primary source in indoor air is resuspended soil from outdoors. In the second rural community, our estimated metal concentrations in air were comparable to active air sampling measurements taken previously. This passive air sampler is a simple low-cost method to assess potential exposures near contaminated mining sites. PMID:24469149

Assessment of phytoremediation ability of Coriander sativum for soil and water co-contaminated with lead and arsenic: a small-scale study.

PubMed

Gaur, Nisha; Kukreja, Aayush; Yadav, Mahavir; Tiwari, Archana

2017-07-01

A study was conducted to access the phytoremediation potential of Coriandrum sativum for lead (Pb) and Arsenic (As). Metal tolerance index and pot experiment were conducted. Viable seeds were spread on filter paper and planted in soil placed in pots. The amount of Pb and As in control and in tailing soil was 0.27, 0.141, 1.77, and 0.35 ppm. The study was carried out in triplicates for a period of 4 weeks under natural conditions. The physico-chemical properties of soil were determined using the standard methods. Germination of seeds of Coriander sativum was inhibited more rigorously in filter paper as compared to soil medium. Shoot height and root length were significantly reduced in filter paper medium under Pb and As stress. These were inhibited by 33 and 40%, respectively, from the first to fourth weeks. Seedling growth was less affected in soil medium while greatly reduced in filter paper medium. Soil sustained almost equal stress in the fourth week as compared to the third week in filter paper medium. Shoot height was enormously affected by Pb and As compared to root length in filter paper medium, whereas slight inhibition of growth was observed in soil medium. Coriander sativum grown in pots was effective in removing Pb and As from control and tailing soils in comparison with seeds grown on filter paper. On this basis, it could be used in restoring soil polluted with Pb and As.

The significance of colloids in the transport of pesticides through Chalk.

PubMed

Gooddy, D C; Mathias, S A; Harrison, I; Lapworth, D J; Kim, A W

2007-10-15

Agrochemical contamination in groundwater poses a significant long term threat to water quality and is of concern for legislators, water utilities and consumers alike. In the dual porosity, dual permeability aquifers such as the Chalk aquifer, movement of pesticides and their metabolites through the unsaturated zone to groundwater is generally considered to be through one of two pathways; a rapid by-pass flow and a slower 'piston-flow' route via the rock matrix. However, the dissolved form or 'colloidal species' in which pesticides move within the water body is poorly understood. Following heavy rainfall, very high peaks in pesticide concentration have been observed in shallow Chalk aquifers. These concentrations might be well explained by colloidal transport of pesticides. We have sampled a Chalk groundwater beneath a deep (30 m) unsaturated zone known to be contaminated with the pesticide diuron. Using a tangential flow filtration technique we have produced colloidal fractions from 0.45 microm to 1 kDa. In addition, we have applied agricultural grade diuron to a typical Chalk soil and created a soil water suspension which was also subsequently fractionated using the same filtration system. The deep groundwater sample showed no evidence of association between colloidal material and pesticide concentration. In comparison, despite some evidence of particle trapping or sorption to the filters, the soil water clearly showed an association between the <0.45 microm and <0.1 microm colloidal fractions which displayed significantly higher pesticide concentrations than the unfiltered sample. Degradation products were also observed and found to behave in a similar manner to the parent compound. Although relatively large colloids can be generated in the Chalk soil zone, it appears transport to depth in a colloidal-bound form does not occur. Comparison with other field and monitoring studies suggests that rapid by-pass flow is unlikely to occur beneath 4-5 m. Therefore, shallow groundwaters are most at risk from rapid transport of high concentrations of pesticide-colloidal complexes. The presence of a deep unsaturated zone will mean that most of the colloidal-complexes will be filtered by the narrow Chalk pores and the majority of pesticide transport will occur in a 'dissolved' form through the more gradual 'piston-flow' route.

Towards an unbiased filter routine to determine precipitation and evapotranspiration from high precision lysimeter measurements

NASA Astrophysics Data System (ADS)

Peters, Andre; Groh, Jannis; Schrader, Frederik; Durner, Wolfgang; Vereecken, Harry; Pütz, Thomas

2017-06-01

Weighing lysimeters are considered to be the best means for a precise measurement of water fluxes at the interface between the soil-plant system and the atmosphere. Any decrease of the net mass of the lysimeter can be interpreted as evapotranspiration (ET), any increase as precipitation (P). However, the measured raw data need to be filtered to separate real mass changes from noise. Such filter routines typically apply two steps: (i) a low pass filter, like moving average, which smooths noisy data, and (ii) a threshold filter that separates significant from insignificant mass changes. Recent developments of these filters have identified and solved some problems regarding bias in the data processing. A remaining problem is that each change in flow direction is accompanied with a systematic flow underestimation due to the threshold scheme. In this contribution, we analyze this systematic effect and show that the absolute underestimation is independent of the magnitude of a flux event. Thus, for small events, like dew or rime formation, the relative error is high and can reach the same magnitude as the flux itself. We develop a heuristic solution to the problem by introducing a so-called "snap routine". The routine is calibrated and tested with synthetic flux data and applied to real measurements obtained with a precision lysimeter for a 10-month period. The heuristic snap routine effectively overcomes these problems and yields an almost unbiased representation of the real signal.

Macroscale water fluxes 3. Effects of land processes on variability of monthly river discharge

USGS Publications Warehouse

Milly, P.C.D.; Wetherald, R.T.

2002-01-01

A salient characteristic of river discharge is its temporal variability. The time series of flow at a point on a river can be viewed as the superposition of a smooth seasonal cycle and an irregular, random variation. Viewing the random component in the spectral domain facilitates both its characterization and an interpretation of its major physical controls from a global perspective. The power spectral density functions of monthly flow anomalies of many large rivers worldwide are typified by a "red noise" process: the density is higher at low frequencies (e.g., <1 y-1) than at high frequencies, indicating disproportionate (relative to uncorrelated "white noise") contribution of low frequencies to variability of monthly flow. For many high-latitude and arid-region rivers, however, the power is relatively evenly distributed across the frequency spectrum. The power spectrum of monthly flow can be interpreted as the product of the power spectrum of monthly basin total precipitation (which is typically white or slightly red) and several filters that have physical significance. The filters are associated with (1) the conversion of total precipitation (sum of rainfall and snowfall) to effective rainfall (liquid flux to the ground surface from above), (2) the conversion of effective rainfall to soil water excess (runoff), and (3) the conversion of soil water excess to river discharge. Inferences about the roles of each filter can be made through an analysis of observations, complemented by information from a global model of the ocean-atmosphere-land system. The first filter causes a snowmelt-related amplification of high-frequency variability in those basins that receive substantial snowfall. The second filter causes a relatively constant reduction in variability across all frequencies and can be predicted well by means of a semiempirical water balance relation. The third filter, associated with groundwater and surface water storage in the river basin, causes a strong reduction in high-frequency variability of many basins. The strength of this reduction can be quantified by an average residence time of water in storage, which is typically on the order of 20-50 days. The residence time is demonstrably influenced by freezing conditions in the basin, fractional cover of the basin by lakes, and runoff ratio (ratio of mean runoff to mean precipitation). Large lake areas enhance storage and can greatly increase total residence times (100 to several hundred days). Freezing conditions appear to cause bypassing of subsurface storage, thus reducing residence times (0-30 days). Small runoff ratios tend to be associated with arid regions, where the water table is deep, and consequently, most of the runoff is produced by processes that bypass the saturated zone, leading to relatively small residence times for such basins (0-40 days).

Influence of solid-liquid separation method parameters employed in soil leaching tests on apparent metal concentration.

PubMed

Imoto, Yukari; Yasutaka, Tetsuo; Someya, Masayuki; Higashino, Kazuo

2018-05-15

Soil leaching tests are commonly used to evaluate the leachability of hazardous materials, such as heavy metals, from the soil. Batch leaching tests often enhance soil colloidal mobility and may require solid-liquid separation procedures to remove excess soil particles. However, batch leaching test results depend on particles that can pass through a 0.45μm membrane filter and are influenced by test parameters such as centrifugal intensity and filtration volume per filter. To evaluate these parameters, we conducted batch leaching experiments using metal-contaminated soils and focused on the centrifugal intensity and filtration volume per filter used in solid-liquid separation methods currently employed in standard leaching tests. Our experiments showed that both centrifugal intensity and filtration volume per filter affected the reproducibility of batch leaching tests for some soil types. The results demonstrated that metal concentrations in the filtrates significantly differed according to the centrifugal intensity when it was 3000 g for 2h or less. Increased filtration volume per filter led to significant decreases in filtrate metal concentrations when filter cakes formed during filtration. Comparison of the filtration tests using 0.10 and 0.45μm membrane filters showed statistically significant differences in turbidity and metal concentration. These findings suggest that colloidal particles were not adequately removed from the extract and contributed substantially to the apparent metal concentrations in the leaching test of soil containing colloidal metals. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

Approximating Phosphorus Leaching from Agricultural Organic Soils by Soil Testing.

PubMed

Zheng, Z M; Zhang, T Q; Kessel, C; Tan, C S; O'Halloran, I P; Wang, Y T; Speranzini, D; Van Eerd, L L

2015-11-01

Phosphorus applied to soils in excess of crop requirement could create situations favorable to P enrichment in subsurface flow that contributes to eutrophication of surface water. This pathway of P loss can be more severe in muck (i.e., organic) soils where agricultural production is intensive. This study evaluated the suitability of various environmental and agronomic soil P tests initially designed for mineral soils to predict dissolved reactive P (DRP) in subsurface flow from organic soils. Intact soil columns were collected from 44 muck soils in Ontario to provide a wide range of soil test P levels. A lysimeter leaching study was conducted by evenly adding water in an amount equivalent to 5 mm of rainfall. The leachate DRP concentration was linearly related to soil water-extractable P and CaCl-extractable P with values of 0.90 and 0.93, respectively, and to Bray-1 P and FeO-impregnated filter paper extractable P in a split-line model with a change point. Mehlich-3 P and Olsen P, a method recommended for agronomic P calibration in Ontario, were not related to leachate DRP concentration. All P sorption index (PSI) based degree of P saturation (DPS) values were closely related to leachate DRP in split-line models, with the DPS indices expressed as Bray-1 P/PSI and FeO-P/PSI having the highest correlation with leachate DRP concentration. Because it is desirable from practical and economic standpoints that the environmental risk assessment shares the same soil test with agronomic P calibration, the two PSI-based DPS indices as presented can be considered as environmental risk indicators of DRP subsurface loss from organic soils. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

Potential of organic filter materials for treating greywater to achieve irrigation quality: a review.

PubMed

Dalahmeh, Sahar S; Hylander, Lars D; Vinnerås, Björn; Pell, Mikael; Oborn, Ingrid; Jönsson, Håkan

2011-01-01

The objectives of this literature review were to: (i) evaluate the impact of greywater generated in rural communities, with the emphasis on Jordanian conditions, on soil, plant and public health and assess the need for treatment of this greywater before it is used for irrigation, and (ii) assess the potential of different types of organic by-products as carrier material in different filter units for removal of pollutants from greywater. Greywater with high BOD5, COD, high concentrations of SS, fat, oil and grease and high levels of surfactants is commonly found in rural areas in Jordan. Oxygen depletion, odour emission, hydrophobic soil phenomena, plant toxicity, blockage of piping systems and microbiological health risks are common problems associated with greywater without previous treatment. Organic by-products such as wood chips, bark, peat, wheat straw and corncob may be used as carrier material in so-called mulch filters for treating wastewater and greywater from different sources. A down-flow-mode vertical filter is a common setup used in mulch filters. Wastewaters with a wide range of SS, cBOD5 and COD fed into different mulch filters have been studied. The different mulch materials achieved SS removal ranging between 51 and 91%, a BOD5 reduction range of 55-99.9%, and COD removal of 51-98%. Most types of mulches achieved a higher organic matter removal than that achieved by an ordinary septic tank. Bark, peat and wood chips filters removed organic matter better than sand and trickling filters, under similar conditions. Release of filter material and increase in COD in the effluent was reported using some mulch materials. In conclusion, some mulch materials such as bark, peat and woodchips seem to have a great potential for treatment of greywater in robust, low-tech systems. They can be expected to be resilient in dealing with variable low and high organic loads and shock loads.

Evaluating the effect of different vegetative filter strip designs on sediment movement in an agricultural watershed using LISEM, Iowa, USA

NASA Astrophysics Data System (ADS)

Luquin Oroz, Eduardo; Cruse, Rick; Baartman, Jantiene; Keesstra, Saskia

2016-04-01

Although restoration of native vegetation in vulnerable areas would decrease soil loss, this approach is not feasible in communities that base their income on agriculture. However, an alternative exists: strategically placing a small percentage of vegetative filter strips (VFS) within agriculture fields for erosion control. Factors influencing their effectiveness are shallow conditions, vegetation type, filter strip width, slope, soil type, and rainfall characteristics. Generally, the first few meters of the strip are where most sediments deposit. For slopes higher than 10%, effectiveness decreases with increasing slope gradient. Usually, high rainfall intensity and sediment load in overland flow decrease vegetative filter strips' effectiveness. Nowadays, Iowa (USA), experiences increasingly stronger rainstorms; climate change is expected to increase rainfall erosive forces between 16 to 58%. Thus, there is a need to obtain new insights about strip design and its influence on sediment dynamics. Therefore, the objective of this study is to analyze strip design (width) impact on soil and water movement. To do so, different strip widths (no strips, 1.5, 3, 5, 7.5 and 10 meters wide) were analyzed under four rainfall intensities (increments of 10, 25, 50 and 75%) The event-based, hydrological and soil erosion model LISEM was used to simulate different scenarios. The model has been calibrated with data from 3-ha 'Interim 1' watershed, which is part of Walnut Creek (Iowa, USA). During a single event with sediment load, on July 18th 2010, intensities reached up to 80 mm/h. Two different land covers exist: (i) perennial vegetation, which has prairie vegetation covering patches and strips; and (ii) row crop agriculture where corn and soybeans are the main two crops in the area. Based on the different combination of widths and intensities, 24 scenarios were generated. At the moment, the model is on the final part of the calibration; scenario results will be presented on the poster.

Nutrient transport through a Vegetative Filter Strip with subsurface drainage.

PubMed

Bhattarai, Rabin; Kalita, Prasanta Kumar; Patel, Mita Kanu

2009-04-01

The transport of nutrients and soil sediments in runoff has been recognized as a noteworthy environmental issue. Vegetative Filter Strips (VFS) have been used as one of the best management practices (BMPs) for retaining nutrients and sediments from surface runoff, thus preventing the pollutants from reaching receiving waters. However, the effectiveness of a VFS when combined with a subsurface drainage system has not been investigated previously. This study was undertaken to monitor the retention and transport of nutrients within a VFS that had a subsurface drainage system installed at a depth of 1.2 m below the soil surface. Nutrient concentrations of NO(3)-N (Nitrate Nitrogen), PO(-)(4) (Orthophosphorus), and TP (Total Phosphorus) were measured in surface water samples (entering and leaving the VFS), and subsurface outflow. Soil samples were collected and analyzed for plant available Phosphorus (Bray P1) and NO(3)-N concentrations. Results showed that PO(-)(4), NO(3)-N, and TP concentrations decreased in surface flow through the VFS. Many surface outflow water samples from the VFS showed concentration reductions of as much as 75% for PO(-)(4) and 70% for TP. For subsurface outflow water samples through the drainage system, concentrations of PO(-)(4) and TP decreased but NO(3)-N concentrations increased in comparison to concentrations in surface inflow samples. Soil samples that were collected from various depths in the VFS showed a minimal buildup of nutrients in the top soil profile but indicated a gradual buildup of nutrients at the depth of the subsurface drain. Results demonstrate that although a VFS can be very effective in reducing runoff and nutrients from surface flow, the presence of a subsurface drain underneath the VFS may not be environmentally beneficial. Such a combination may increase NO(3)-N transport from the VFS, thus invalidating the purpose of the BMP.

Method and apparatus for a self-cleaning filter

DOEpatents

Diebold, James P.; Lilley, Arthur; Browne, III, Kingsbury; Walt, Robb Ray; Duncan, Dustin; Walker, Michael; Steele, John; Fields, Michael

2013-09-10

A method and apparatus for removing fine particulate matter from a fluid stream without interrupting the overall process or flow. The flowing fluid inflates and expands the flexible filter, and particulate is deposited on the filter media while clean fluid is permitted to pass through the filter. This filter is cleaned when the fluid flow is stopped, the filter collapses, and a force is applied to distort the flexible filter media to dislodge the built-up filter cake. The dislodged filter cake falls to a location that allows undisrupted flow of the fluid after flow is restored. The shed particulate is removed to a bin for periodic collection. A plurality of filter cells can operate independently or in concert, in parallel, or in series to permit cleaning the filters without shutting off the overall fluid flow. The self-cleaning filter is low cost, has low power consumption, and exhibits low differential pressures.

Method and apparatus for a self-cleaning filter

DOEpatents

Diebold, James P.; Lilley, Arthur; Browne, III, Kingsbury; Walt, Robb Ray; Duncan, Dustin; Walker, Michael; Steele, John; Fields, Michael

2010-11-16

A method and apparatus for removing fine particulate matter from a fluid stream without interrupting the overall process or flow. The flowing fluid inflates and expands the flexible filter, and particulate is deposited on the filter media while clean fluid is permitted to pass through the filter. This filter is cleaned when the fluid flow is stopped, the filter collapses, and a force is applied to distort the flexible filter media to dislodge the built-up filter cake. The dislodged filter cake falls to a location that allows undisrupted flow of the fluid after flow is restored. The shed particulate is removed to a bin for periodic collection. A plurality of filter cells can operate independently or in concert, in parallel, or in series to permit cleaning the filters without shutting off the overall fluid flow. The self-cleaning filter is low cost, has low power consumption, and exhibits low differential pressures.

Two size-selective mechanisms specifically trap bacteria-sized food particles in Caenorhabditis elegans.

PubMed

Fang-Yen, Christopher; Avery, Leon; Samuel, Aravinthan D T

2009-11-24

Caenorhabditis elegans is a filter feeder: it draws bacteria suspended in liquid into its pharynx, traps the bacteria, and ejects the liquid. How pharyngeal pumping simultaneously transports and filters food particles has been poorly understood. Here, we use high-speed video microscopy to define the detailed workings of pharyngeal mechanics. The buccal cavity and metastomal flaps regulate the flow of dense bacterial suspensions and exclude excessively large particles from entering the pharynx. A complex sequence of contractions and relaxations transports food particles in two successive trap stages before passage into the terminal bulb and intestine. Filtering occurs at each trap as bacteria are concentrated in the central lumen while fluids are expelled radially through three apical channels. Experiments with microspheres show that the C. elegans pharynx, in combination with the buccal cavity, is tuned to specifically catch and transport particles of a size range corresponding to most soil bacteria.

Two size-selective mechanisms specifically trap bacteria-sized food particles in Caenorhabditis elegans

PubMed Central

Fang-Yen, Christopher; Avery, Leon; Samuel, Aravinthan D. T.

2009-01-01

Caenorhabditis elegans is a filter feeder: it draws bacteria suspended in liquid into its pharynx, traps the bacteria, and ejects the liquid. How pharyngeal pumping simultaneously transports and filters food particles has been poorly understood. Here, we use high-speed video microscopy to define the detailed workings of pharyngeal mechanics. The buccal cavity and metastomal flaps regulate the flow of dense bacterial suspensions and exclude excessively large particles from entering the pharynx. A complex sequence of contractions and relaxations transports food particles in two successive trap stages before passage into the terminal bulb and intestine. Filtering occurs at each trap as bacteria are concentrated in the central lumen while fluids are expelled radially through three apical channels. Experiments with microspheres show that the C. elegans pharynx, in combination with the buccal cavity, is tuned to specifically catch and transport particles of a size range corresponding to most soil bacteria. PMID:19903886

Optimal hydrograph separation using a recursive digital filter constrained by chemical mass balance, with application to selected Chesapeake Bay watersheds

USGS Publications Warehouse

Raffensperger, Jeff P.; Baker, Anna C.; Blomquist, Joel D.; Hopple, Jessica A.

2017-06-26

Quantitative estimates of base flow are necessary to address questions concerning the vulnerability and response of the Nation’s water supply to natural and human-induced change in environmental conditions. An objective of the U.S. Geological Survey National Water-Quality Assessment Project is to determine how hydrologic systems are affected by watershed characteristics, including land use, land cover, water use, climate, and natural characteristics (geology, soil type, and topography). An important component of any hydrologic system is base flow, generally described as the part of streamflow that is sustained between precipitation events, fed to stream channels by delayed (usually subsurface) pathways, and more specifically as the volumetric discharge of water, estimated at a measurement site or gage at the watershed scale, which represents groundwater that discharges directly or indirectly to stream reaches and is then routed to the measurement point.Hydrograph separation using a recursive digital filter was applied to 225 sites in the Chesapeake Bay watershed. The recursive digital filter was chosen for the following reasons: it is based in part on the assumption that groundwater acts as a linear reservoir, and so has a physical basis; it has only two adjustable parameters (alpha, obtained directly from recession analysis, and beta, the maximum value of the base-flow index that can be modeled by the filter), which can be determined objectively and with the same physical basis of groundwater reservoir linearity, or that can be optimized by applying a chemical-mass-balance constraint. Base-flow estimates from the recursive digital filter were compared with those from five other hydrograph-separation methods with respect to two metrics: the long-term average fraction of streamflow that is base flow, or base-flow index, and the fraction of days where streamflow is entirely base flow. There was generally good correlation between the methods, with some biased slightly high and some biased slightly low compared to the recursive digital filter. There were notable differences between the days at base flow estimated by the different methods, with the recursive digital filter having a smaller range of values. This was attributed to how the different methods determine cessation of quickflow (the part of streamflow which is not base flow).For 109 Chesapeake Bay watershed sites with available specific conductance data, the parameters of the filter were optimized using a chemical-mass-balance constraint and two different models for the time-dependence of base-flow specific conductance. Sixty-seven models were deemed acceptable and the results compared well with non-optimized results. There are a number of limitations to the optimal hydrograph-separation approach resulting from the assumptions implicit in the conceptual model, the mathematical model, and the approach taken to impose chemical mass balance (including tracer choice). These limitations may be evidenced by poor model results; conversely, poor model fit may provide an indication that two-component separation does not adequately describe the hydrologic system’s runoff response.The results of this study may be used to address a number of questions regarding the role of groundwater in understanding past changes in stream-water quality and forecasting possible future changes, such as the timing and magnitude of land-use and management practice effects on stream and groundwater quality. Ongoing and future modeling efforts may benefit from the estimates of base flow as calibration targets or as a means to filter chemical data to model base-flow loads and trends. Ultimately, base-flow estimation might provide the basis for future work aimed at improving the ability to quantify groundwater discharge, not only at the scale of a gaged watershed, but at the scale of individual reaches as well.

Shallow water table effects on water, sediment, and pesticide transport in vegetative filter strips - Part 2: model coupling, application, factor importance, and uncertainty

NASA Astrophysics Data System (ADS)

Lauvernet, Claire; Muñoz-Carpena, Rafael

2018-01-01

Vegetative filter strips are often used for protecting surface waters from pollution transferred by surface runoff in agricultural watersheds. In Europe, they are often prescribed along the stream banks, where a seasonal shallow water table (WT) could decrease the buffer zone efficiency. In spite of this potentially important effect, there are no systematic experimental or theoretical studies on the effect of this soil boundary condition on the VFS efficiency. In the companion paper (Muñoz-Carpena et al., 2018), we developed a physically based numerical algorithm (SWINGO) that allows the representation of soil infiltration with a shallow water table. Here we present the dynamic coupling of SWINGO with VFSMOD, an overland flow and transport mathematical model to study the WT influence on VFS efficiency in terms of reductions of overland flow, sediment, and pesticide transport. This new version of VFSMOD was applied to two contrasted benchmark field studies in France (sandy-loam soil in a Mediterranean semicontinental climate, and silty clay in a temperate oceanic climate), where limited testing of the model with field data on one of the sites showed promising results. The application showed that for the conditions of the studies, VFS efficiency decreases markedly when the water table is 0 to 1.5 m from the surface. In order to evaluate the relative importance of WT among other input factors controlling VFS efficiency, global sensitivity and uncertainty analysis (GSA) was applied on the benchmark studies. The most important factors found for VFS overland flow reduction were saturated hydraulic conductivity and WT depth, added to sediment characteristics and VFS dimensions for sediment and pesticide reductions. The relative importance of WT varied as a function of soil type (most important at the silty-clay soil) and hydraulic loading (rainfall + incoming runoff) at each site. The presence of WT introduced more complex responses dominated by strong interactions in the modeled system response, reducing the typical predominance of saturated hydraulic conductivity on infiltration under deep water table conditions. This study demonstrates that when present, the WT should be considered as a key hydrologic factor in buffer design and evaluation as a water quality mitigation practice.

Evolution of an interfacial crack on the concrete-embankment boundary

DOE Office of Scientific and Technical Information (OSTI.GOV)

Glascoe, Lee; Antoun, Tarabay; Kanarska, Yuliya

2013-07-10

Failure of a dam can have subtle beginnings. A small crack or dislocation at the interface of the concrete dam and the surrounding embankment soil initiated by, for example, a seismic or an explosive event can lead to a catastrophic failure of the dam. The dam may ‘self-rehabilitate’ if a properly designed granular filter is engineered around the embankment. Currently, the design criteria for such filters have only been based on experimental studies. We demonstrate the numerical prediction of filter effectiveness at the soil grain scale. This joint LLNL-ERDC basic research project, funded by the Department of Homeland Security’s Sciencemore » and Technology Directorate (DHS S&T), consists of validating advanced high performance computer simulations of soil erosion and transport of grain- and dam-scale models to detailed centrifuge and soil erosion tests. Validated computer predictions highlight that a resilient filter is consistent with the current design specifications for dam filters. These predictive simulations, unlike the design specifications, can be used to assess filter success or failure under different soil or loading conditions and can lead to meaningful estimates of the timing and nature of full-scale dam failure.« less

High flow ceramic pot filters.

PubMed

van Halem, D; van der Laan, H; Soppe, A I A; Heijman, S G J

2017-11-01

Ceramic pot filters are considered safe, robust and appropriate technologies, but there is a general consensus that water revenues are limited due to clogging of the ceramic element. The objective of this study was to investigate the potential of high flow ceramic pot filters to produce more water without sacrificing their microbial removal efficacy. High flow pot filters, produced by increasing the rice husk content, had a higher initial flow rate (6-19 L h -1 ), but initial LRVs for E. coli of high flow filters was slightly lower than for regular ceramic pot filters. This disadvantage was, however, only temporarily as the clogging in high flow filters had a positive effect on the LRV for E. coli (from below 1 to 2-3 after clogging). Therefore, it can be carefully concluded that regular ceramic pot filters perform better initially, but after clogging, the high flow filters have a higher flow rate as well as a higher LRV for E. coli. To improve the initial performance of new high flow filters, it is recommended to further utilize residence time of the water in the receptacle, since additional E. coli inactivation was observed during overnight storage. Although a relationship was observed between flow rate and LRV of MS2 bacteriophages, both regular and high flow filters were unable to reach over 2 LRV. Copyright © 2017 Elsevier Ltd. All rights reserved.

Effect of vegetated filter strips on transport and deposition rates of Escherichia coli in overland flow in the eastern escarpments of the Mau Forest, Njoro River Watershed, Kenya

PubMed Central

Onyando, J. O.; Moturi, W. N.; Muia, A. W.; Ombui, P.; Shivoga, W. A.; Roegner, A. F.

2016-01-01

The fate and transport of Escherichia coli (E. coli) in lotic waters through vegetated filter strips (VFSs) was evaluated in a field model pasture, utilizing VFSMOD Windows along with direct pathogen testing. This study assessed effects of VFS on transport and deposition rates of E. coli in lotic overland flow waters. The VFS measured 44 m long by 40 m wide, covering an area of 1584 m2 and land slope of 15 %. Cowpat was applied onto the model pasture and washed by overland flow into the VFS. The 4-methylumbelliferyl β-D-glucuronide substrate confirmed the identity of E. coli prior to cowpat application and after isolating them from soil using centrifugation and membrane filtration techniques. Napier grass root system recorded the highest recovery rates of E. coli at 99.9 % along the length of VFS III. This efficiency reduced significantly (p < 0.05; df = 29) to 95 % in Kikuyu grass and 75 % in Couch grass–Buffer grass. The data demonstrated similarity in transport of manure-borne E. coli and organic carbon (OC) through all the simulated VFS. These results indicated that OC could be used as a true natural tracer of manure-borne E. coli, a pollution indicator organism of lentic and lotic surface waters provided the OC release kinetics from cowpat were similar to that of E. coli kinetics. Thus, efficient filtering to reduce E. coli concentrations and load in overland flows requires managing combined grass species, agro-pastoral systems models and dispersed or preferential flows to enhance surface water quality standards. PMID:28393102

Comparison of cellulose vs. plastic cigarette filter decomposition under distinct disposal environments.

PubMed

Joly, François-Xavier; Coulis, Mathieu

2018-02-01

It is estimated that 4.5 trillion cigarette butts are discarded annually, making them numerically the most common type of litter on Earth. To accelerate their disappearance after disposal, a new type of cigarette filters made of cellulose, a readily biodegradable compound, has been introduced in the market. Yet, the advantage of these cellulose filters over the conventional plastic ones (cellulose acetate) for decomposition, remains unknown. Here, we compared the decomposition of cellulose and plastic cigarettes filters, either intact or smoked, on the soil surface or within a composting bin over a six-month field decomposition experiment. Within the compost, cellulose filters decomposed faster than plastic filters, but this advantage was strongly reduced when filters had been used for smoking. This indicates that the accumulation of tars and other chemicals during filter use can strongly affect its subsequent decomposition. Strikingly, on the soil surface, we observed no difference in mass loss between cellulose and plastic filters throughout the incubation. Using a first order kinetic model for mass loss of for used filters over the short period of our experiment, we estimated that conventional plastic filters take 7.5-14 years to disappear, in the compost and on the soil surface, respectively. In contrast, we estimated that cellulose filters take 2.3-13 years to disappear, in the compost and on the soil surface, respectively. Our data clearly showed that disposal environments and the use of cellulose filters must be considered when assessing their advantage over plastic filters. In light of our results, we advocate that the shift to cellulose filters should not exempt users from disposing their waste in appropriate collection systems. Copyright © 2017 Elsevier Ltd. All rights reserved.

Soil separator and sampler and method of sampling

DOEpatents

O'Brien, Barry H [Idaho Falls, ID; Ritter, Paul D [Idaho Falls, ID

2010-02-16

A soil sampler includes a fluidized bed for receiving a soil sample. The fluidized bed may be in communication with a vacuum for drawing air through the fluidized bed and suspending particulate matter of the soil sample in the air. In a method of sampling, the air may be drawn across a filter, separating the particulate matter. Optionally, a baffle or a cyclone may be included within the fluidized bed for disentrainment, or dedusting, so only the finest particulate matter, including asbestos, will be trapped on the filter. The filter may be removable, and may be tested to determine the content of asbestos and other hazardous particulate matter in the soil sample.

Estimating soil matric potential in Owens Valley, California

USGS Publications Warehouse

Sorenson, Stephen K.; Miller, Reuben F.; Welch, Michael R.; Groeneveld, David P.; Branson, Farrel A.

1989-01-01

Much of the floor of Owens Valley, California, is covered with alkaline scrub and alkaline meadow plant communities, whose existence is dependent partly on precipitation and partly on water infiltrated into the rooting zone from the shallow water table. The extent to which these plant communities are capable of adapting to and surviving fluctuations in the water table depends on physiological adaptations of the plants and on the water content, matric potential characteristics of the soils. Two methods were used to estimate soil matric potential in test sites in Owens Valley. The first, the filter-paper method, uses water content of filter papers equilibrated to water content of soil samples taken with a hand auger. The previously published calibration relations used to estimate soil matric potential from the water content of the filter papers were modified on the basis of current laboratory data. The other method of estimating soil matric potential was a modeling approach based on data from this and previous investigations. These data indicate that the base-10 logarithm of soil matric potential is a linear function of gravimetric soil water content for a particular soil. The slope and intercepts of this function vary with the texture and saturation capacity of the soil. Estimates of soil water characteristic curves were made at two sites by averaging the gravimetric soil water content and soil matric potential values from multiple samples at 0.1-m depth intervals derived by using the hand auger and filter-paper method and entering these values in the soil water model. The characteristic curves then were used to estimate soil matric potential from estimates of volumetric soil water content derived from neutron-probe readings. Evaluation of the modeling technique at two study sites indicated that estimates of soil matric potential within 0.5 pF units of the soil matric potential value derived by using the filter-paper method could be obtained 90 to 95 percent of the time in soils where water content was less than field capacity. The greatest errors occurred at depths where there was a distinct transition between soils of different textures.

Particulate and colloidal silver in sewage effluent and sludge discharged from British wastewater treatment plants.

PubMed

Johnson, Andrew C; Jürgens, Monika D; Lawlor, Alan J; Cisowska, Iwona; Williams, Richard J

2014-10-01

Differential filtration was used to measure silver (>2 nm) entering and leaving nine sewage treatment plants (STPs). The mean concentration of colloidal (2-450 nm) silver, which includes nanosilver, was found to be 12 ng L(-1) in the influent and 6 ng L(-1) in the effluent. For particulate silver (>450 nm) the mean values were 3.3 μg L(-1) for influent and 0.08 μg L(-1) for effluent. Thus, removal was around 50% and 98% for colloidal and particulate silver respectively. There was no significant difference in performance between the different types of STP investigated (three examples each of activated sludge, biological filter and biological filter with tertiary treatment located across England, UK). In addition, treated sewage sludge samples (biosolids) were taken from several STPs to measure the total silver likely to be discharged to soils. Total silver was 3-14 mg kg(-1) DW in the sludge (median 3.6), which if the sludge were added at the recommended rate to soil, would add 11 μg kg(-1) yr(-1) to the top 20 cm soil layer. Predicted concentrations using the LF2000-WQX model for all the rivers of England and Wales for nanosilver were typically in the 0-1 ng L(-1) range but levels up to 4 ng L(-1) are possible in a high discharge and low flow scenario. Predicted concentrations for the total particulate forms were mostly below 50 ng L(-1) except for a high discharge and low flow scenario where concentrations could reach 135 ng L(-1). Copyright © 2014 Elsevier Ltd. All rights reserved.

Concentric Split Flow Filter

NASA Technical Reports Server (NTRS)

Stapleton, Thomas J. (Inventor)

2015-01-01

A concentric split flow filter may be configured to remove odor and/or bacteria from pumped air used to collect urine and fecal waste products. For instance, filter may be designed to effectively fill the volume that was previously considered wasted surrounding the transport tube of a waste management system. The concentric split flow filter may be configured to split the air flow, with substantially half of the air flow to be treated traveling through a first bed of filter media and substantially the other half of the air flow to be treated traveling through the second bed of filter media. This split flow design reduces the air velocity by 50%. In this way, the pressure drop of filter may be reduced by as much as a factor of 4 as compare to the conventional design.

Mobilization of microspheres from a fractured soil during intermittent infiltration events

USGS Publications Warehouse

Mohanty, Sanjay; Bulicek, Mark; Metge, David W.; Harvey, Ronald W.; Ryan, Joseph N.; Boehm, Alexandria B.

2015-01-01

Pathogens or biocolloids mobilized in the vadose zone may consequently contaminate groundwater. We found that microspheres were mobilized from a fractured soil during intermittent rainfall and the mobilization was greater when the microsphere size was larger and when the soil had greater water permeability.The vadose zone filters pathogenic microbes from infiltrating water and consequently protects the groundwater from possible contamination. In some cases, however, the deposited microbes may be mobilized during rainfall and migrate into the groundwater. We examined the mobilization of microspheres, surrogates for microbes, in an intact core of a fractured soil by intermittent simulated rainfall. Fluorescent polystyrene microspheres of two sizes (0.5 and 1.8 mm) and Br− were first applied to the core to deposit the microspheres, and then the core was subjected to three intermittent infiltration events to mobilize the deposited microspheres. Collecting effluent samples through a 19-port sampler at the base of the core, we found that water flowed through only five ports, and the flow rates varied among the ports by a factor of 12. These results suggest that flow paths leading to the ports had different permeabilities, partly due to macropores. Although 40 to 69% of injected microspheres were retained in the core during their application, 12 to 30% of the retained microspheres were mobilized during three intermittent infiltration events. The extent of microsphere mobilization was greater in flow paths with greater permeability, which indicates that macropores could enhance colloid mobilization during intermittent infiltration events. In all ports, the 1.8-mm microspheres were mobilized to a greater extent than the 0.5-mm microspheres, suggesting that larger colloids are more likely to mobilize. These results are useful in assessing the potential of pathogen mobilization and colloid-facilitated transport of contaminants in the subsurface under natural infiltration events.

Volcanic emissions from soils at the base of La Fossa volcano, Vulcano island, Italy

NASA Astrophysics Data System (ADS)

Obenholzner, J. H.; Parks, J. L.

2006-12-01

A top-sealed plastic tube with a diameter of ca. 15 cm had been buried vertically at the base of La Fossa volcano, Volcano island, Italy, next to the front of the obsidian flow. The tube had been filled with quartz wool to condense vapors emanating from the soil. At ca. 75 cm below the surface the sample had been exposed to vapors from Sept. 2005 to April 2006. The leached sample had not been in touch with the ground. Another glass wool cushion (ca. 3 cm thick) had been underneath to minimize capillary effects. Leaching of the quartz wool and ICP-MS analysis documented positive values for: Mg, Al, Si, P, K, Ca, Cr, Mn, Ni, Cu, Zn, Cd, Sn, Pb. Leaching with nitric acid documented also V and Fe. Acid leaching produced higher values for all elements, except K and Sn, than leaching with deionized water. Negative values had been obtained for As, Se, Mo. Influence from soil breathing can be excluded as the active fumaroles contain As and Se. This experiment documents for the first time an unknown element transport by vapors/gases through a volcanic edifice interacting with hydrothermal and magmatic gases. It remains unknown if elements detected are entering the atmosphere or are getting adsorbed onto the volcanic ash soil particles derived from reworked surge beds. This question is very important as soils might be an unknown filter medium to filter volcanically polluted air in case of major volcanic crises. Data can be obtained from the authors.

Sustainable colloidal-silver-impregnated ceramic filter for point-of-use water treatment.

PubMed

Oyanedel-Craver, Vinka A; Smith, James A

2008-02-01

Cylindrical colloidal-silver-impregnated ceramic filters for household (point-of-use) water treatment were manufactured and tested for performance in the laboratory with respect to flow rate and bacteria transport. Filters were manufactured by combining clay-rich soil with water, grog (previously fired clay), and flour, pressing them into cylinders, and firing them at 900 degrees C for 8 h. The pore-size distribution of the resulting ceramic filters was quantified by mercury porosimetry. Colloidal silver was applied to filters in different quantities and ways (dipping and painting). Filters were also tested without any colloidal-silver application. Hydraulic conductivity of the filters was quantified using changing-head permeability tests. [3H]H2O water was used as a conservative tracer to quantify advection velocities and the coefficient of hydrodynamic dispersion. Escherichia coli (E. coli) was used to quantify bacterial transport through the filters. Hydraulic conductivity and pore-size distribution varied with filter composition; hydraulic conductivities were on the order of 10(-5) cm/s and more than 50% of the pores for each filter had diameters ranging from 0.02 to 15 microm. The filters removed between 97.8% and 100% of the applied bacteria; colloidal-silver treatments improved filter performance, presumably by deactivation of bacteria. The quantity of colloidal silver applied per filter was more important to bacteria removal than the method of application. Silver concentrations in effluent filter water were initially greater than 0.1 mg/L, but dropped below this value after 200 min of continuous operation. These results indicate that colloidal-silver-impregnated ceramic filters, which can be made using primarily local materials and labor, show promise as an effective and sustainable point-of-use water treatment technology for the world's poorest communities.

Application of Micropore Filter Technology: Exploring the Blood Flow Path in Arterial-Line Filters and Its Effect on Bubble Trapping Functions

PubMed Central

Herbst, Daniel P.

2017-01-01

Abstract: Conventional arterial-line filters commonly use a large volume circular shaped housing, a wetted micropore screen, and a purge port to trap, separate, and remove gas bubbles from extracorporeal blood flow. Focusing on the bubble trapping function, this work attempts to explore how the filter housing shape and its resulting blood flow path affect the clinical application of arterial-line filters in terms of gross air handling. A video camera was used in a wet-lab setting to record observations made during gross air-bolus injections in three different radially designed filters using a 30–70% glycerol–saline mixture flowing at 4.5 L/min. Two of the filters both had inlet ports attached near the filter-housing top with bottom oriented outlet ports at the bottom, whereas the third filter had its inlet and outlet ports both located at the bottom of the filter housing. The two filters with top-in bottom-out fluid paths were shown to direct the incoming flow downward as it passed through the filter, placing the forces of buoyancy and viscous drag in opposition to each other. This contrasted with the third filter's bottom-in bottom-out fluid path, which was shown to direct the incoming flow upward so that the forces of buoyancy and viscous drag work together. The direction of the blood flow path through a filter may be important to the application of arterial-line filter technology as it helps determine how the forces of buoyancy and flow are aligned with one another. PMID:28298665

Application of Micropore Filter Technology: Exploring the Blood Flow Path in Arterial-Line Filters and Its Effect on Bubble Trapping Functions.

PubMed

Herbst, Daniel P

2017-03-01

Conventional arterial-line filters commonly use a large volume circular shaped housing, a wetted micropore screen, and a purge port to trap, separate, and remove gas bubbles from extracorporeal blood flow. Focusing on the bubble trapping function, this work attempts to explore how the filter housing shape and its resulting blood flow path affect the clinical application of arterial-line filters in terms of gross air handling. A video camera was used in a wet-lab setting to record observations made during gross air-bolus injections in three different radially designed filters using a 30-70% glycerol-saline mixture flowing at 4.5 L/min. Two of the filters both had inlet ports attached near the filter-housing top with bottom oriented outlet ports at the bottom, whereas the third filter had its inlet and outlet ports both located at the bottom of the filter housing. The two filters with top-in bottom-out fluid paths were shown to direct the incoming flow downward as it passed through the filter, placing the forces of buoyancy and viscous drag in opposition to each other. This contrasted with the third filter's bottom-in bottom-out fluid path, which was shown to direct the incoming flow upward so that the forces of buoyancy and viscous drag work together. The direction of the blood flow path through a filter may be important to the application of arterial-line filter technology as it helps determine how the forces of buoyancy and flow are aligned with one another.

Movement of coliform bacteria and nutrients in ground water flowing through basalt and sand aquifers.

PubMed

Entry, J A; Farmer, N

2001-01-01

Large-scale deposition of animal manure can result in contamination of surface and ground water and in potential transfer of disease-causing enteric bacteria to animals or humans. We measured total coliform bacteria (TC), fecal coliform bacteria (FC), NO3, NH4, total P, and PO4 in ground water flowing from basalt and sand aquifers, in wells into basalt and sand aquifers, in irrigation water, and in river water. Samples were collected monthly for 1 yr. Total coliform and FC numbers were always higher in irrigation water than in ground water, indicating that soil and sediment filtered most of these bacteria before they entered the aquifers. Total coliform and FC numbers in ground water were generally higher in the faster flowing basalt aquifer than in the sand aquifer, indicating that the slower flow and finer grain size may filter more TC and FC bacteria from water. At least one coliform bacterium/100 mL of water was found in ground water from both basalt and sand aquifers, indicating that ground water pumped from these aquifers is not necessarily safe for human consumption according to the American Public Health Association and the USEPA. The NO3 concentrations were usually higher in water flowing from the sand aquifer than in water flowing from the basalt aquifer or in perched water tables in the basalt aquifer. The PO4 concentrations were usually higher in water flowing from the basalt aquifer than in water flowing from the sand aquifer. The main concern is fecal contamination of these aquifers and health consequences that may arise from human consumption.

Data assimilation for groundwater flow modelling using Unbiased Ensemble Square Root Filter: Case study in Guantao, North China Plain

NASA Astrophysics Data System (ADS)

Li, N.; Kinzelbach, W.; Li, H.; Li, W.; Chen, F.; Wang, L.

2017-12-01

Data assimilation techniques are widely used in hydrology to improve the reliability of hydrological models and to reduce model predictive uncertainties. This provides critical information for decision makers in water resources management. This study aims to evaluate a data assimilation system for the Guantao groundwater flow model coupled with a one-dimensional soil column simulation (Hydrus 1D) using an Unbiased Ensemble Square Root Filter (UnEnSRF) originating from the Ensemble Kalman Filter (EnKF) to update parameters and states, separately or simultaneously. To simplify the coupling between unsaturated and saturated zone, a linear relationship obtained from analyzing inputs to and outputs from Hydrus 1D is applied in the data assimilation process. Unlike EnKF, the UnEnSRF updates parameter ensemble mean and ensemble perturbations separately. In order to keep the ensemble filter working well during the data assimilation, two factors are introduced in the study. One is called damping factor to dampen the update amplitude of the posterior ensemble mean to avoid nonrealistic values. The other is called inflation factor to relax the posterior ensemble perturbations close to prior to avoid filter inbreeding problems. The sensitivities of the two factors are studied and their favorable values for the Guantao model are determined. The appropriate observation error and ensemble size were also determined to facilitate the further analysis. This study demonstrated that the data assimilation of both model parameters and states gives a smaller model prediction error but with larger uncertainty while the data assimilation of only model states provides a smaller predictive uncertainty but with a larger model prediction error. Data assimilation in a groundwater flow model will improve model prediction and at the same time make the model converge to the true parameters, which provides a successful base for applications in real time modelling or real time controlling strategies in groundwater resources management.

Assimilating Remotely Sensed Surface Soil Moisture into SWAT using Ensemble Kalman Filter

USDA-ARS?s Scientific Manuscript database

In this study, a 1-D Ensemble Kalman Filter has been used to update the soil moisture states of the Soil and Water Assessment Tool (SWAT) model. Experiments were conducted for the Cobb Creek Watershed in southeastern Oklahoma for 2006-2008. Assimilation of in situ data proved limited success in the ...

Multi-decadal analysis of root-zone soil moisture applying the exponential filter across CONUS

USDA-ARS?s Scientific Manuscript database

his study applied the exponential filter to produce an estimate of root-zone soil moisture (RZSM). Four types of microwave-based, surface satellite soil moisture were used. The core remotely sensed data for this study came from NASA’s long lasting AMSR-E mission. Additionally three other products we...

PERFORMANCE IMPROVEMENT OF CROSS-FLOW FILTRATION FOR HIGH LEVEL WASTE TREATMENT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Duignan, M.; Nash, C.; Poirier, M.

2011-01-12

In the interest of accelerating waste treatment processing, the DOE has funded studies to better understand filtration with the goal of improving filter fluxes in existing cross-flow equipment. The Savannah River National Laboratory (SRNL) was included in those studies, with a focus on start-up techniques, filter cake development, the application of filter aids (cake forming solid precoats), and body feeds (flux enhancing polymers). This paper discusses the progress of those filter studies. Cross-flow filtration is a key process step in many operating and planned waste treatment facilities to separate undissolved solids from supernate slurries. This separation technology generally has themore » advantage of self-cleaning through the action of wall shear stress created by the flow of waste slurry through the filter tubes. However, the ability of filter wall self-cleaning depends on the slurry being filtered. Many of the alkaline radioactive wastes are extremely challenging to filtration, e.g., those containing compounds of aluminum and iron, which have particles whose size and morphology reduce permeability. Unfortunately, low filter flux can be a bottleneck in waste processing facilities such as the Savannah River Modular Caustic Side Solvent Extraction Unit and the Hanford Waste Treatment Plant. Any improvement to the filtration rate would lead directly to increased throughput of the entire process. To date increased rates are generally realized by either increasing the cross-flow filter axial flowrate, limited by pump capacity, or by increasing filter surface area, limited by space and increasing the required pump load. SRNL set up both dead-end and cross-flow filter tests to better understand filter performance based on filter media structure, flow conditions, filter cleaning, and several different types of filter aids and body feeds. Using non-radioactive simulated wastes, both chemically and physically similar to the actual radioactive wastes, the authors performed several tests to demonstrate increases in filter performance. With the proper use of filter flow conditions and filter enhancers, filter flow rates can be increased over rates currently realized today.« less

Winery wastewater treatment using the land filter technique.

PubMed

Christen, E W; Quayle, W C; Marcoux, M A; Arienzo, M; Jayawardane, N S

2010-08-01

This study outlines a new approach to the treatment of winery wastewater by application to a land FILTER (Filtration and Irrigated cropping for Land Treatment and Effluent Reuse) system. The land FILTER system was tested at a medium size rural winery crushing approximately 20,000 tonnes of grapes. The approach consisted of a preliminary treatment through a coarse screening and settling in treatment ponds, followed by application to the land FILTER planted to pasture. The land FILTER system efficiently dealt with variable volumes and nutrient loads in the wastewater. It was operated to minimize pollutant loads in the treated water (subsurface drainage) and provide adequate leaching to manage salt in the soil profile. The land FILTER system was effective in neutralizing the pH of the wastewater and removing nutrient pollutants to meet EPA discharge limits. However, suspended solids (SS) and biological oxygen demand (BOD) levels in the subsurface drainage waters slightly exceeded EPA limits for discharge. The high organic content in the wastewater initially caused some soil blockage and impeded drainage in the land FILTER site. This was addressed by reducing the hydraulic loading rate to allow increased soil drying between wastewater irrigations. The analysis of soil characteristics after the application of wastewater found that there was some potassium accumulation in the profile but sodium and nutrients decreased after wastewater application. Thus, the wastewater application and provision of subsurface drainage ensured adequate leaching, and so was adequate to avoid the risk of soil salinisation. Crown Copyright 2010. Published by Elsevier Ltd. All rights reserved.

Integrating biofiltration with SVE: A case study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lesley, M.P.; Rangan, C.R.

1996-12-01

A prototype integrated soil vacuum extraction/biofiltration system has been designed and installed at a gasoline contaminated LUST site in southern Delaware. The prototype system remediates contaminated moisture entrained in the air stream, employs automatic water level controls in the filters, and achieves maximum vapor extraction and VOC destruction efficiency with an optimum power input. In addition, the valving and piping layout allows the direction of air flow through the filters to be reversed at a given time interval, which minimizes biofouling, thereby increasing efficiency by minimizing the need for frequent cleaning. This integrated system achieves constant VOC destruction rates ofmore » 40 to 70% while maintaining optimal VOC removal rates from the subsurface. The modular design allows for easy mobilization, setup and demobilization at state-lead LUST sites throughout Delaware.« less

Evaluation of an Infiltration Model with Microchannels

NASA Astrophysics Data System (ADS)

Garcia-Serrana, M.; Gulliver, J. S.; Nieber, J. L.

2015-12-01

This research goal is to develop and demonstrate the means by which roadside drainage ditches and filter strips can be assigned the appropriate volume reduction credits by infiltration. These vegetated surfaces convey stormwater, infiltrate runoff, and filter and/or settle solids, and are often placed along roads and other impermeable surfaces. Infiltration rates are typically calculated by assuming that water flows as sheet flow over the slope. However, for most intensities water flow occurs in narrow and shallow micro-channels and concentrates in depressions. This channelization reduces the fraction of the soil surface covered with the water coming from the road. The non-uniform distribution of water along a hillslope directly affects infiltration. First, laboratory and field experiments have been conducted to characterize the spatial pattern of flow for stormwater runoff entering onto the surface of a sloped surface in a drainage ditch. In the laboratory experiments different micro-topographies were tested over bare sandy loam soil: a smooth surface, and three and five parallel rills. All the surfaces experienced erosion; the initially smooth surface developed a system of channels over time that increased runoff generation. On average, the initially smooth surfaces infiltrated 10% more volume than the initially rilled surfaces. The field experiments were performed in the side slope of established roadside drainage ditches. Three rates of runoff from a road surface into the swale slope were tested, representing runoff from 1, 2, and 10-year storm events. The average percentage of input runoff water infiltrated in the 32 experiments was 67%, with a 21% standard deviation. Multiple measurements of saturated hydraulic conductivity were conducted to account for its spatial variability. Second, a rate-based coupled infiltration and overland model has been designed that calculates stormwater infiltration efficiency of swales. The Green-Ampt-Mein-Larson assumptions were implemented to calculate infiltration along with a kinematic wave model for overland flow that accounts for short-circuiting of flow. Additionally, a sensitivity analysis on the parameters implemented in the model has been performed. Finally, the field experiments results have been used to quantify the validity of the coupled model.

Controlled laboratory experiments and modeling of vegetative filter strips with shallow water tables

NASA Astrophysics Data System (ADS)

Fox, Garey A.; Muñoz-Carpena, Rafael; Purvis, Rebecca A.

2018-01-01

Natural or planted vegetation at the edge of fields or adjacent to streams, also known as vegetative filter strips (VFS), are commonly used as an environmental mitigation practice for runoff pollution and agrochemical spray drift. The VFS position in lowlands near water bodies often implies the presence of a seasonal shallow water table (WT). In spite of its potential importance, there is limited experimental work that systematically studies the effect of shallow WTs on VFS efficacy. Previous research recently coupled a new physically based algorithm describing infiltration into soils bounded by a water table into the VFS numerical overland flow and transport model, VFSMOD, to simulate VFS dynamics under shallow WT conditions. In this study, we tested the performance of the model against laboratory mesoscale data under controlled conditions. A laboratory soil box (1.0 m wide, 2.0 m long, and 0.7 m deep) was used to simulate a VFS and quantify the influence of shallow WTs on runoff. Experiments included planted Bermuda grass on repacked silt loam and sandy loam soils. A series of experiments were performed including a free drainage case (no WT) and a static shallow water table (0.3-0.4 m below ground surface). For each soil type, this research first calibrated VFSMOD to the observed outflow hydrograph for the free drainage experiments to parameterize the soil hydraulic and vegetation parameters, and then evaluated the model based on outflow hydrographs for the shallow WT experiments. This research used several statistical metrics and a new approach based on hypothesis testing of the Nash-Sutcliffe model efficiency coefficient (NSE) to evaluate model performance. The new VFSMOD routines successfully simulated the outflow hydrographs under both free drainage and shallow WT conditions. Statistical metrics considered the model performance valid with greater than 99.5% probability across all scenarios. This research also simulated the shallow water table experiments with both free drainage and various water table depths to quantify the effect of assuming the former boundary condition. For these two soil types, shallow WTs within 1.0-1.2 m below the soil surface influenced infiltration. Existing models will suggest a more protective vegetative filter strip than what actually exists if shallow water table conditions are not considered.

Modelling dynamic transport and adsorption of arsenic in soil-bed filters for long-term performance evaluation

NASA Astrophysics Data System (ADS)

Mondal, Sourav; Mondal, Raka; de, Sirshendu; Griffiths, Ian

2017-11-01

Purification of contaminated water following the safe water guidelines while generating sufficiently large throughput is a crucial requirement for the steady supply of safe water to large populations. Adsorption-based filtration processes using a multilayer soil bed has been posed as a viable method to achieve this goal. This work describes the theory of operation and prediction of the long-term behaviour of such a system. The fixed-bed column has a single input of contaminated water from the top and an output from the bottom. As the contaminant passes through the column, it is adsorbed by the medium. Like any other adsorption medium, the filter has a certain lifespan, beyond which the filtrate does not meet the safe limit of drinking water, which is defined as `breakthrough'. A mathematical model is developed that couples the fluid flow through the porous medium to the convective, diffusive and adsorptive transport of the contaminant. The results are validated with experimental observations and the model is then used to predict the breakthrough and lifetime of the filter. The key advantage of this model is that it can predict the long-term behaviour of any adsorption column system for any set of physical characteristics of the system. This worked was supported by the EPSRC Global Challenge Research Fund Institutional Sponsorship 2016.

One-dimensional soil temperature assimilation experiment based on unscented particle filter and Common Land Model

NASA Astrophysics Data System (ADS)

Fu, Xiao Lei; Jin, Bao Ming; Jiang, Xiao Lei; Chen, Cheng

2018-06-01

Data assimilation is an efficient way to improve the simulation/prediction accuracy in many fields of geosciences especially in meteorological and hydrological applications. This study takes unscented particle filter (UPF) as an example to test its performance at different two probability distribution, Gaussian and Uniform distributions with two different assimilation frequencies experiments (1) assimilating hourly in situ soil surface temperature, (2) assimilating the original Moderate Resolution Imaging Spectroradiometer (MODIS) Land Surface Temperature (LST) once per day. The numerical experiment results show that the filter performs better when increasing the assimilation frequency. In addition, UPF is efficient for improving the soil variables (e.g., soil temperature) simulation/prediction accuracy, though it is not sensitive to the probability distribution for observation error in soil temperature assimilation.

Cadmium in smoke particulates of regular and filter cigarettes containing low and high cadmium concentrations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bache, C.A.; Reid, C.M.; Hoffman, D.

In the work reported, filter and nonfilter cigarettes were prepared from high-cadmium tobacco grown on a municipal sludge-amended soil or a low-cadmium tobacco grown on untreated soil alone. These were smoked by machine to determine the effectiveness of the cigarette filters in possibly reducing the quantities of cadmium in the mainstream smoke particulates.

Ensemble Data Assimilation for Streamflow Forecasting: Experiments with Ensemble Kalman Filter and Particle Filter

NASA Astrophysics Data System (ADS)

Hirpa, F. A.; Gebremichael, M.; Hopson, T. M.; Wojick, R.

2011-12-01

We present results of data assimilation of ground discharge observation and remotely sensed soil moisture observations into Sacramento Soil Moisture Accounting (SACSMA) model in a small watershed (1593 km2) in Minnesota, the Unites States. Specifically, we perform assimilation experiments with Ensemble Kalman Filter (EnKF) and Particle Filter (PF) in order to improve streamflow forecast accuracy at six hourly time step. The EnKF updates the soil moisture states in the SACSMA from the relative errors of the model and observations, while the PF adjust the weights of the state ensemble members based on the likelihood of the forecast. Results of the improvements of each filter over the reference model (without data assimilation) will be presented. Finally, the EnKF and PF are coupled together to further improve the streamflow forecast accuracy.

Sources and sinks of filtered total mercury and concentrations of total mercury of solids and of filtered methylmercury, Sinclair Inlet, Kitsap County, Washington, 2007-10

USGS Publications Warehouse

Paulson, Anthony J.; Dinicola, Richard S.; Noble, Marlene A.; Wagner, Richard J.; Huffman, Raegan L.; Moran, Patrick W.; DeWild, John F.

2012-01-01

The majority of filtered total mercury in the marine water of Sinclair Inlet originates from salt water flowing from Puget Sound. About 420 grams of filtered total mercury are added to Sinclair Inlet each year from atmospheric, terrestrial, and sedimentary sources, which has increased filtered total mercury concentrations in Sinclair Inlet (0.33 nanograms per liter) to concentrations greater than those of the Puget Sound (0.2 nanograms per liter). The category with the largest loading of filtered total mercury to Sinclair Inlet included diffusion of porewaters from marine sediment to the water column of Sinclair Inlet and discharge through the largest stormwater drain on the Bremerton naval complex, Bremerton, Washington. However, few data are available to estimate porewater and stormwater releases with any certainty. The release from the stormwater drain does not originate from overland flow of stormwater. Rather total mercury on soils is extracted by the chloride ions in seawater as the stormwater is drained and adjacent soils are flushed with seawater by tidal pumping. Filtered total mercury released by an unknown freshwater mechanism also was observed in the stormwater flowing through this drain. Direct atmospheric deposition on the Sinclair Inlet, freshwater discharge from creek and stormwater basins draining into Sinclair Inlet, and saline discharges from the dry dock sumps of the naval complex are included in the next largest loading category of sources of filtered total mercury. Individual discharges from a municipal wastewater treatment plant and from the industrial steam plant of the naval complex constituted the loading category with the third largest loadings. Stormwater discharge from the shipyard portion of the naval complex and groundwater discharge from the base are included in the loading category with the smallest loading of filtered total mercury. Presently, the origins of the solids depositing to the sediment of Sinclair Inlet are uncertain, and consequently, concentrations of sediments can be qualitatively compared only to total mercury concentrations of solids suspended in the water column. Concentrations of total mercury of suspended solids from creeks, stormwater, and even wastewater effluent discharging into greater Sinclair Inlet were comparable to concentrations of solids suspended in the water column of Sinclair Inlet. Concentrations of total mercury of suspended solids were significantly lower than those of marine bed sediment of Sinclair Inlet; these suspended solids have been shown to settle in Sinclair Inlet. The settling of suspended solids in the greater Sinclair Inlet and in Operable Unit B Marine of the naval complex likely will result in lower concentrations of total mercury in sediments. Such a decrease in total mercury concentrations was observed in the sediment of Operable Unit B Marine in 2010. However, total mercury concentrations of solids discharged from several sources from the Bremerton naval complex were higher than concentrations in sediment collected from Operable Unit B Marine. The combined loading of solids from these sources is small compared to the amount of solids depositing in OU B Marine. However, total mercury concentration in sediment collected at a monitoring station just offshore one of these sources, the largest stormwater drain on the Bremerton naval complex, increased considerably in 2010. Low methylmercury concentrations were detected in groundwater, stormwater, and effluents discharged from the Bremerton naval complex. The highest methylmercury concentrations were measured in the porewaters of highly reducing marine sediment in greater Sinclair Inlet. The marine sediment collected off the largest stormwater drain contained low concentrations of methylmercury in porewater because these sediments were not highly reducing.

Flow regions of granules in Dorfan Impingo filter for gas cleanup

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kuo, J.T.; Smid, J.; Hsiau, S.S.

1999-07-01

Inside a two-dimensional model of the louvered Dorfan Impingo panel with transparent front and rear walls the flow region of filter granules without gas cross flow were observed. The white PE beads were used as filter granules. Colored PE beads served as tracers. Filter granules were discharged and circulated to the bed. The flow rate of filter medium was controlled by the belt conveyor. The image processing system including a Frame Grabber and JVC videocamera was used to record the granular flow. Every image of motion was digitized and stored in a file. The flow patterns and the quasi-stagnant zonesmore » history in the moving granular bed were evaluated. The experiment showed fast central moving region (flowing core) of filter granules and quasi-stagnant zones close to louver walls.« less

Fate of Cryptosporidium parvum oocysts within soil, water, and plant environment.

PubMed

McLaughlin, Stephen J; Kalita, Prasanta K; Kuhlenschmidt, Mark S

2013-12-15

Vegetative Filter Strips (VFS) have long been used to control the movement of agricultural nutrients and prevent them from reaching receiving waters. Earlier studies have shown that VFS also dramatically reduce both the kinetics and extent of Cryptosporidium parvum (C. parvum) oocysts overland transport. In this study, we investigated possible mechanisms responsible for the ability of VFS to reduce oocyst overland transport. Measurement of the kinetics of C. parvum adhesion to individual sand, silt, and clay soil particles revealed that oocysts associate over time, albeit relatively slow, with clay but not silt or sand particles. Measurement of oocyst overland transport kinetics, soil infiltration depth, distance of travel, and adhesion to vegetation on bare and vegetated soil surfaces indicate that oocysts move more slowly, and penetrate the soil profile to a greater extent on a vegetated surface than on a bare soil surface. Furthermore, we demonstrate a small fraction of the oocysts become attached to vegetation at the soil-vegetation interface on VFS. These results suggest VFS function to reduce oocyst overland transport by primarily decreasing oocyst surface flow enough to allow penetration within the soil profile followed by subsequent adhesion to or entrapment within clay particle aggregates, and to a lesser extent, adhesion to the surface vegetation. Copyright © 2013 Elsevier Ltd. All rights reserved.

Modeling Flow Past a Tilted Vena Cava Filter

DOE Office of Scientific and Technical Information (OSTI.GOV)

Singer, M A; Wang, S L

Inferior vena cava filters are medical devices used to prevent pulmonary embolism (PE) from deep vein thrombosis. In particular, retrievable filters are well-suited for patients who are unresponsive to anticoagulation therapy and whose risk of PE decreased with time. The goal of this work is to use computational fluid dynamics to evaluate the flow past an unoccluded and partially occluded Celect inferior vena cava filter. In particular, the hemodynamic response to thrombus volume and filter tilt is examined, and the results are compared with flow conditions that are known to be thrombogenic. A computer model of the filter inside amore » model vena cava is constructed using high resolution digital photographs and methods of computer aided design. The models are parameterized using the Overture software framework, and a collection of overlapping grids is constructed to discretize the flow domain. The incompressible Navier-Stokes equations are solved, and the characteristics of the flow (i.e., velocity contours and wall shear stresses) are computed. The volume of stagnant and recirculating flow increases with thrombus volume. In addition, as the filter increases tilt, the cava wall adjacent to the tilted filter is subjected to low velocity flow that gives rise to regions of low wall shear stress. The results demonstrate the ease of IVC filter modeling with the Overture software framework. Flow conditions caused by the tilted Celect filter may elevate the risk of intrafilter thrombosis and facilitate vascular remodeling. This latter condition also increases the risk of penetration and potential incorporation of the hook of the filter into the vena caval wall, thereby complicating filter retrieval. Consequently, severe tilt at the time of filter deployment may warrant early clinical intervention.« less

Estimating soil matric potential in Owens Valley, California

USGS Publications Warehouse

Sorenson, Stephen K.; Miller, R.F.; Welch, M.R.; Groeneveld, D.P.; Branson, F.A.

1988-01-01

Much of the floor of the Owens Valley, California, is covered with alkaline scrub and alkaline meadow plant communities, whose existence is dependent partly on precipitation and partly on water infiltrated into the rooting zone from the shallow water table. The extent to which these plant communities are capable of adapting to and surviving fluctuations in the water table depends on physiological adaptations of the plants and on the water content, matric potential characteristics of the soils. Two methods were used to estimate soil matric potential in test sites in Owens Valley. The first was the filter-paper method, which uses water content of filter papers equilibrated to water content of soil samples taken with a hand auger. The other method of estimating soil matric potential was a modeling approach based on data from this and previous investigations. These data indicate that the base 10 logarithm of soil matric potential is a linear function of gravimetric soil water content for a particular soil. Estimates of soil water characteristic curves were made at two sites by averaging the gravimetric soil water content and soil matric potential values from multiple samples at 0.1 m depths derived by using the hand auger and filter paper method and entering these values in the soil water model. The characteristic curves then were used to estimate soil matric potential from estimates of volumetric soil water content derived from neutron-probe readings. Evaluation of the modeling technique at two study sites indicated that estimates of soil matric potential within 0.5 pF units of the soil matric potential value derived by using the filter paper method could be obtained 90 to 95% of the time in soils where water content was less than field capacity. The greatest errors occurred at depths where there was a distinct transition between soils of different textures. (Lantz-PTT)

Use of sugarcane filter cake and nitrogen, phosphorus and potassium fertilization in the process of bioremediation of soil contaminated with diesel.

PubMed

Tellechea, Fernando Reynel Fundora; Martins, Marco Antônio; da Silva, Alexsandro Araujo; da Gama-Rodrigues, Emanuela Forestieri; Martins, Meire Lelis Leal

2016-09-01

This study evaluated the use of sugarcane filter cake and nitrogen, phosphorus and potassium (NPK) fertilization in the bioremediation of a soil contaminated with diesel fuel using a completely randomized design. Five treatments (uncontaminated soil, T1; soil contaminated with diesel, T2; soil contaminated with diesel and treated with 15 % (wt) filter cake, T3; soil contaminated with diesel and treated with NPK fertilizer, T4; and soil contaminated with diesel and treated with 15 % (wt) filter cake and NPK fertilizer, T5) and four evaluation periods (1, 60, 120, and 180 days after the beginning of the experiment) were used according to a 4 × 5 factorial design to analyze CO2 release. The variables total organic carbon (TOC) and total petroleum hydrocarbons (TPH) remaining in the soil were analyzed using a 5 × 2 factorial design, with the same treatments described above and two evaluation periods (1 and 180 days after the beginning of the experiment). In T3 and T5, CO2 release was significantly higher, compared with the other treatments. Significant TPH removal was observed on day 180, when percent removal values were 61.9, 70.1, 68.2, and 75.9 in treatments T2, T3, T4, and T5, respectively, compared with the initial value (T1).

Soil bacterial communities are shaped by temporal and environmental filtering: evidence from a long-term chronosequence.

PubMed

Freedman, Zachary; Zak, Donald R

2015-09-01

Soil microbial communities are abundant, hyper-diverse and mediate global biogeochemical cycles, but we do not yet understand the processes mediating their assembly. Current hypothetical frameworks suggest temporal (e.g. dispersal limitation) and environmental (e.g. soil pH) filters shape microbial community composition; however, there is limited empirical evidence supporting this framework in the hyper-diverse soil environment, particularly at large spatial (i.e. regional to continental) and temporal (i.e. 100 to 1000 years) scales. Here, we present evidence from a long-term chronosequence (4000 years) that temporal and environmental filters do indeed shape soil bacterial community composition. Furthermore, nearly 20 years of environmental monitoring allowed us to control for potentially confounding environmental variation. Soil bacterial communities were phylogenetically distinct across the chronosequence. We determined that temporal and environmental factors accounted for significant portions of bacterial phylogenetic structure using distance-based linear models. Environmental factors together accounted for the majority of phylogenetic structure, namely, soil temperature (19%), pH (17%) and litter carbon:nitrogen (C:N; 17%). However, of all individual factors, time since deglaciation accounted for the greatest proportion of bacterial phylogenetic structure (20%). Taken together, our results provide empirical evidence that temporal and environmental filters act together to structure soil bacterial communities across large spatial and long-term temporal scales. © 2015 Society for Applied Microbiology and John Wiley & Sons Ltd.

Estimating the water budget for a peat filter treating septic tank effluent in the field

NASA Astrophysics Data System (ADS)

Van Geel, Paul J.; Parker, Wayne J.

2003-02-01

The use of peat as a filter medium for the treatment of a variety of liquid and gas waste streams has increased over the past decade. Peat has been used as an alternate treatment medium to treat septic tank effluent (STE) from domestic and small communal systems. Very little research has been completed to study the hydraulics and water budget of a peat filter operating in the field. This study evaluated the water budget of a peat filter operating at an elementary school near Ottawa, Canada. The peat filter was instrumented with tensiometers to measure the pore water pressures within the filter and a weather station to collect weather data required to estimate potential evapotranspiration. A one-dimensional unsaturated flow model, SoilCover, was calibrated using the pressure data and weather data collected in the field. The calibrated model was use to estimate the water budget for the filter operating with and without STE loading. The calibrated model predicted that the annual precipitation exceeded evapotranspiration for both scenarios. For the filter treating 50 mm/day of STE, there was a slight dilution due to the infiltration resulting in a net dilution factor of 0.97 (loading divided by the loading plus infiltration). The largest rainfall event of 49.9 mm resulted in a dilution factor of approximately 0.87, which corresponded to an approximate decrease in the hydraulic retention time (HRT) of between 12 and 33% depending on the calculation used to determine the HRT. When the filter does not receive STE, the precipitation exceeds evapotranspiration and hence the filter should not dry out when the filter is not in use.

Field application of farmstead runoff to vegetated filter strips: surface and subsurface water quality assessment.

PubMed

Larson, Rebecca A; Safferman, Steven I

2012-01-01

Farmstead runoff poses significant environmental impacts to ground and surface waters. Three vegetated filter strips were assessed for the treatment of dairy farmstead runoff at the soil surface and subsurface at 0.3- or 0. 46-m and 0. 76-m depths for numerous storm events. A medium-sized Michigan dairy was retrofitted with two filter strips on sandy loam soil and a third filter strip was implemented on a small Michigan dairy with sandy soil to collect and treat runoff from feed storage, manure storage, and other impervious farmstead areas. All filter strips were able to eliminate surface runoff via infiltration for all storm events over the duration of the study, eliminating pollutant contributions to surface water. Subsurface effluent was monitored to determine the contributing groundwater concentrations of numerous pollutants including chemical oxygen demand (COD), metals, and nitrates. Subsurface samples have an average reduction of COD concentrations of 20, 11, and 85% for the medium dairy Filter Strip 1 (FS1), medium dairy Filter Strip 2 (FS2), and the small Michigan dairy respectively, resulting in average subsurface concentrations of 355, 3960, and 718 mg L COD. Similar reductions were noted for ammonia and total Kjeldahl nitrogen (TKN) in the subsurface effluent. The small Michigan dairy was able to reduce the pollutant leachate concentrations of COD, TKN, and ammonia over a range of influent concentrations. Increased influent concentrations in the medium Michigan dairy filter strips resulted in an increase in COD, TKN, and ammonia concentrations in the leachate. Manganese was leached from the native soils at all filter strips as evidenced by the increase in manganese concentrations in the leachate. Nitrate concentrations were above standard drinking water limits (10 mg L), averaging subsurface concentrations of 11, 45, and 25 mg L NO-N for FS1, FS2, and the small Michigan dairy, respectively. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

Modeling of two-dimensional overland flow in a vegetative filter

Treesearch

Matthew J. Helmers; Dean E. Eisenhauer; Thomas G. Franti; Michael G. Dosskey

2002-01-01

Water transports sediment and other pollutants through vegetative filters. It is often assumed that the overland flow is uniformly distributed across the vegetative filter, but this research indicates otherwise. The objective of this study was to model the two-dimensional overland water flow through a vegetative filter, accounting for variation in microtopography,...

Contaminate Control Device

NASA Technical Reports Server (NTRS)

Howe, Robert H. (Inventor); Flynn, Kenneth P. (Inventor); Stapleton, Thomas J. (Inventor)

2014-01-01

A contaminate control device for filtering contaminates from a gas such as air is provided. The device includes a housing having a first inlet and a first outlet. An axial flow filter is fluidly coupled between the first inlet and the first outlet, the axial flow filter has a second inlet and a second outlet. A second filter disposed about the axial flow filter and is fluidly coupled between the first inlet and the first outlet, the second filter having a third inlet on an inner diameter and a third outlet disposed on an outer diameter. A flow restrictor is fluidly coupled between the second inlet and the first inlet.

Method and apparatus for measuring flow velocity using matched filters

DOEpatents

Raptis, Apostolos C.

1983-01-01

An apparatus and method for measuring the flow velocities of individual phase flow components of a multiphase flow utilizes matched filters. Signals arising from flow noise disturbance are extracted from the flow, at upstream and downstream locations. The signals are processed through pairs of matched filters which are matched to the flow disturbance frequency characteristics of the phase flow component to be measured. The processed signals are then cross-correlated to determine the transit delay time of the phase flow component between sensing positions.

Usefulness of dual protection combined with blood aspiration for distal embolic protection during carotid artery stenting.

PubMed

Sakamoto, Shigeyuki; Kiura, Yoshihiro; Okazaki, Takahito; Shinagawa, Katsuhiro; Ichinose, Nobuhiko; Shibukawa, Masaaki; Orita, Yoji; Shimonaga, Koji; Kajihara, Yosuke; Kurisu, Kaoru

2015-03-01

We describe dual protection (simultaneous flow reversal and distal filter) combined with blood aspiration as a novel technique to provide distal embolic protection during carotid artery stenting (CAS). Between July 2011 and August 2014, 190 patients with internal carotid artery (ICA) stenosis underwent 190 CAS procedures as follows. After post-dilation of the stent using dual protection, the aspiration catheter was placed between the distal filter and the proximal end of the stent, and the blood was aspirated several times from the ICA. We assessed hyper-intensity spots in diffusion-weighted images (DWI), and major adverse events (MAE) defined as major stroke, myocardial infarction and death after CAS. We then assessed visible debris captured in aspirated blood, the distal filter and a blood filter during flow reversal. The overall technical success rate was 100 %, and all stenoses were dilated. Hyper-intense spots were found in 33 (17.3 %) of 190 DWI. The rate of MAE within 30 days was 1.05 % (2/190). Visible debris in 175 of 190 CAS procedures was captured in 92 (52.5 %) of these 175. In 25 (27.2 %) of these 92, visible debris was captured in all of aspirated blood, the distal filter and the blood filter during flow reversal, only the blood filter during flow reversal (n = 19; 20.7 %), only the distal filter (n = 14; 15.2 %), only aspirated blood (n = 11; 12 %), aspirated blood and the blood filter during flow reversal (n = 10; 10.8 %), aspirated blood and the distal filter (n = 7; 7.6 %) and the distal filter and blood filter during flow reversal (n = 6; 6.5 %). Adding a distal filter and blood aspiration to flow reversal during CAS could provide effective distal embolic protection.

Potential of filter-vermicomposter for household wastewater pre-treatment and sludge sanitisation on site.

PubMed

Gajurel, D; Deegener, S; Shalabi, M; Otterpohl, R

2007-01-01

Septic tank systems have been widely used to separate and digest solid matter in the household wastewater for a long time. However, they contaminate groundwater with pathogens and nutrients and deprive agriculture of valuable nutrients and soil conditioner from human excreta. Compared with septic tank systems the filter-composter (Rottebehaelter), which usually consists of an underground monolithic concrete tank having two filter beds at its bottom or two filter bags that are hung side by side and used alternately at intervals of 6-12 months, is an efficient component for solid-liquid separation, pre-treatment and collection/storage of solid matter in household wastewater. The solids are retained and decompose in the filter bags or on the filter bed while the liquid filters through. However, because of the high moisture content of the retained solids decomposition is slow. Therefore, secondary treatment of the retained solids is required for sanitisation. The breakthrough was the combination of vermicomposting with the filter-composter system. Relatively dry and stable retained materials were obtained in the filter bags in about 3 months only. No secondary treatment is required as the human excreta will be converted to vermicastings, which are hygienically safe and can be reused as soil conditioner. Therefore, further development of the filter-composter with vermicomposting is worthwhile, especially the aspects of sanitisation of the faecal matter and its reuse as a soil conditioner.

Optimal Filter Estimation for Lucas-Kanade Optical Flow

PubMed Central

Sharmin, Nusrat; Brad, Remus

2012-01-01

Optical flow algorithms offer a way to estimate motion from a sequence of images. The computation of optical flow plays a key-role in several computer vision applications, including motion detection and segmentation, frame interpolation, three-dimensional scene reconstruction, robot navigation and video compression. In the case of gradient based optical flow implementation, the pre-filtering step plays a vital role, not only for accurate computation of optical flow, but also for the improvement of performance. Generally, in optical flow computation, filtering is used at the initial level on original input images and afterwards, the images are resized. In this paper, we propose an image filtering approach as a pre-processing step for the Lucas-Kanade pyramidal optical flow algorithm. Based on a study of different types of filtering methods and applied on the Iterative Refined Lucas-Kanade, we have concluded on the best filtering practice. As the Gaussian smoothing filter was selected, an empirical approach for the Gaussian variance estimation was introduced. Tested on the Middlebury image sequences, a correlation between the image intensity value and the standard deviation value of the Gaussian function was established. Finally, we have found that our selection method offers a better performance for the Lucas-Kanade optical flow algorithm.

Methods for the preparation and analysis of solids and suspended solids for total mercury

USGS Publications Warehouse

Olund, Shane D.; DeWild, John F.; Olson, Mark L.; Tate, Michael T.

2004-01-01

The methods documented in this report are utilized by the Wisconsin District Mercury Lab for analysis of total mercury in solids (soils and sediments) and suspended solids (isolated on filters). Separate procedures are required for the different sample types. For solids, samples are prepared by room-temperature acid digestion and oxidation with aqua regia. The samples are brought up to volume with a 5 percent bromine monochloride solution to ensure complete oxidation and heated at 50?C in an oven overnight. Samples are then analyzed with an automated flow injection system incorporating a cold vapor atomic fluorescence spectrometer. A method detection limit of 0.3 ng of mercury per digestion bomb was established using multiple analyses of an environmental sample. Based on the range of masses processed, the minimum sample reporting limit varies from 0.6 ng/g to 6 ng/g. Suspended solids samples are oxidized with a 5 percent bromine monochloride solution and held at 50?C in an oven for 5 days. The samples are then analyzed with an automated flow injection system incorporating a cold vapor atomic fluorescence spectrometer. Using a certified reference material as a surrogate for an environmental sample, a method detection limit of 0.059 ng of mercury per filter was established. The minimum sample reporting limit varies from 0.059 ng/L to 1.18 ng/L, depending on the volume of water filtered.

Herbicide sorption to fine particulate matter suspended downwind of agricultural operations: field and laboratory investigations.

PubMed

Clymo, Amelia S; Shin, Jin Young; Holmen, Britt A

2005-01-15

Tillage-induced erosion of herbicides bound to airborne soil particles has not been quantified as a mechanism for offsite herbicide transport. This study quantifies the release of two preemergent herbicides, metolachlor and pendimethalin, to the atmosphere as gas- and particle-phase species during soil incorporation operations. Fine particulate matter (PM2.5) and gas-phase samples were collected at three sampling heights during herbicide disking into the soil in Davis, CA, in May 2000 and May 2001 using filter/PUF sampling. Quartz fiber filters (QFFs) were used in May 2000, and Teflon membrane filters (TMFs) were used in May 2001. The field data were combined with laboratory filter/PUF partitioning experiments to account for adsorption to the filter surfaces and quantify the mass of PM2.5-bound herbicides in the field samples. Laboratory results indicate a significant adsorption of metolachlor, but not pendimethalin, to the quartz filter surfaces. Metolachlor partitioning to PM2.5 collected on TMF filters resulted in corrected PM2.5 field partition coefficient values, Kp,corr = Cp/Cg, of approximately 10(-3.5) m3/microg, indicating its preference for the gas phase. Pendimethalin exhibited more semivolatile behavior,with Kp,corr values that ranged from 10(-3) to 10(-1) m3/ microg and increased with sampling height and distance downwind of the operation. An increase in pendimethalin enrichment at a height of 5 m suggests winnowing of finer, more sorptive soil components with corresponding higher transport potential. Pendimethalin was enriched in the PM2.5 samples by up to a factor of 250 compared to the field soil, indicating thatfurther research on the processes controlling the generation of PM-bound herbicides during agricultural operations is warranted to enable prediction of off-site mass fluxes by this mechanism.

Microbial community diversity in agroforestry and grass vegetative filter strips

USDA-ARS?s Scientific Manuscript database

Vegetative filter strips (VFS) have long been promoted as a soil conservation practice that yields many additional environmental benefits. Most previous studies have focused primarily on the role of vegetation and/or soil physical properties in these ecosystem services. Few studies have investigated...

A multilayer concentric filter device to diminish clogging for separation of particles and microalgae based on size.

PubMed

Chen, Chih-Chung; Chen, Yu-An; Liu, Yi-Ju; Yao, Da-Jeng

2014-04-21

Microalgae species have great economic importance; they are a source of medicines, health foods, animal feeds, industrial pigments, cosmetic additives and biodiesel. Specific microalgae species collected from the environment must be isolated for examination and further application, but their varied size and culture conditions make their isolation using conventional methods, such as filtration, streaking plate and flow cytometric sorting, labour-intensive and costly. A separation device based on size is one of the most rapid, simple and inexpensive methods to separate microalgae, but this approach encounters major disadvantages of clogging and multiple filtration steps when the size of microalgae varies over a wide range. In this work, we propose a multilayer concentric filter device with varied pore size and is driven by a centrifugation force. The device, which includes multiple filter layers, was employed to separate a heterogeneous population of microparticles into several subpopulations by filtration in one step. A cross-flow to attenuate prospective clogging was generated by altering the rate of rotation instantly through the relative motion between the fluid and the filter according to the structural design of the device. Mixed microparticles of varied size were tested to demonstrate that clogging was significantly suppressed due to a highly efficient separation. Microalgae in a heterogeneous population collected from an environmental soil collection were separated and enriched into four subpopulations according to size in a one step filtration process. A microalgae sample contaminated with bacteria and insect eggs was also tested to prove the decontamination capability of the device.

Define and Quantify the Physics of Air Flow, Pressure Drop and Aerosol Collection in Nuclear Grade HEPA Filters

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moore, Murray E.

Objective: Develop a set of peer-review and verified analytical methods to adjust HEPA filter performance to different flow rates, temperatures and altitudes. Experimental testing will measure HEPA filter flow rate, pressure drop and efficiency to verify the analytical approach. Nuclear facilities utilize HEPA (High Efficiency Particulate Air) filters to purify air flow for workspace ventilation. However, the ASME AG-1 technical standard (Code on Nuclear Air and Gas Treatment) does not adequately describe air flow measurement units for HEPA filter systems. Specifically, the AG-1 standard does not differentiate between volumetric air flow in ACFM (actual cubic feet per minute)compared to massmore » flow measured in SCFM (standard cubic feet per minute). More importantly, the AG-1 standard has an overall deficiency for using HEPA filter devices at different air flow rates, temperatures, and altitudes. Technical Approach: The collection efficiency and pressure drops of 18 different HEPA filters will be measured over a range of flow rates, temperatures and altitudes. The experimental results will be compared to analytical scoping calculations. Three manufacturers have allocated six HEPA filters each for this effort. The 18 filters will be tested at two different flow rates, two different temperatures and two different altitudes. The 36 total tests will be conducted at two different facilities: the ATI Test facilities (Baltimore MD) and the Los Alamos National Laboratory (Los Alamos NM). The Radiation Protection RP-SVS group at Los Alamos has an aerosol wind tunnel that was originally designed to evaluate small air samplers. In 2010, modifications were started to convert the wind tunnel for HEPA filter testing. (Extensive changes were necessary for the required aerosol generators, HEPA test fixtures, temperature control devices and measurement capabilities.) To this date, none of these modification activities have been funded through a specific DOE or NNSA program. This is expected to require six months of time, after receipt of funding. Benefits: US DOE facilities that use HEPA filters will benefit from access to the new operational measurement methods. Uncertainty and guesswork will be removed from HEPA filter operations.« less

Filter desulfation system and method

DOEpatents

Lowe, Michael D.; Robel, Wade J.; Verkiel, Maarten; Driscoll, James J.

2010-08-10

A method of removing sulfur from a filter system of an engine includes continuously passing an exhaust flow through a desulfation leg of the filter system during desulfation. The method also includes sensing at least one characteristic of the exhaust flow and modifying a flow rate of the exhaust flow during desulfation in response to the sensing.

Evaluation of the spatial variability of soil water content at the spatial resolution of SMAP data products : case studies in Italy and Morocco

NASA Astrophysics Data System (ADS)

Menenti, Massimo; Akdim, Nadia; Alfieri, Silvia Maria; Labbassi, Kamal; De Lorenzi, Francesca; Bonfante, Antonello; Basile, Angelo

2014-05-01

Frequent and contiguous observations of soil water content such as the ones to be provided by SMAP are potentially useful to improve distributed models of soil water balance. This requires matching of observations and model estimates provided both sample spatial patterns consistently. The spatial resolution of SMAP soil water content data products ranges from 3 km X 3 km to 40 km X 40 km. Even the highest spatial resolution may not be sufficient to capture the spatial variability due to terrain, soil properties and precipitation. We have evaluated the SMAP spatial resolution against spatial variability of soil water content in two Mediterranean landscapes: a hilly area dominated by vineyards and olive orchards in Central Italy and a large irrigation schemes (Doukkala) in Morocco. The "Valle Telesina" is a 20,000 ha complex landscape located in South Italy in the Campania region, which has a complex geology and geomorphology and it is characterised by an E-W elongated graben where the Calore river flows. The main crops are grapevine (6,448 ha) and olive (3,390 ha). Soil information was mainly derived from an existing soil map at 1:50 000 scale (Terribile et al., 1996). The area includes 47 SMUs (Soil Mapping Units) and about 60 soil typological units (STUs). (Bonfante et al., 2011). In Doukkala, the soil water retention and unsaturated capillary conductivity were estimated from grain size distribution of a number of samples (22 pilot points, each one sampled in 3 horizons of 20cm), and combined with a soil map. The land use classification was carried out using a NDVI time series at high spatial resolution (Landsat TM and SPOT HRV). We have calculated soil water content for each soil unit in each area in response to several climate cases generating daily maps of soil water content at different depths. To reproduce spatial sampling by SMAP we have filtered these spatial patterns by calculating box averages with grid sizes of 1 km X 1 km and 5 km X 5 km. We have repeated this procedure for soil water content in the 0 to 5 cm and 0 to 10 cm depths. For each case we have compared the variance of filtered soil water content with the expected accuracy of SMAP soil water content. The two areas are very different as regards morphology and soil formation. The Valle Telesina is characterized by a very significant variability of soil hydrological properties leading to complex patterns in soil water content. Contrariwise, the soil properties estimated for all soil mapping units in the Dhoukkala collapse into just two pairs of water retention and hydraulic conductivity characteristics, leading to smoother patterns of soil water content.

Method and apparatus for measuring flow velocity using matched filters

DOEpatents

Raptis, A.C.

1983-09-06

An apparatus and method for measuring the flow velocities of individual phase flow components of a multiphase flow utilizes matched filters. Signals arising from flow noise disturbance are extracted from the flow, at upstream and downstream locations. The signals are processed through pairs of matched filters which are matched to the flow disturbance frequency characteristics of the phase flow component to be measured. The processed signals are then cross-correlated to determine the transit delay time of the phase flow component between sensing positions. 8 figs.

Long-term toxic effects of deltamethrin and fenvalerante in soil.

PubMed

Song, Yufang; Kai, Jianrong; Song, Xueying; Zhang, Wei; Li, Lingling

2015-05-30

In this study, the long-term toxic effects of pyrethroids on the earthworm Eisenia fetida were evaluated. Earthworms were exposed to moist filter paper and soil for 14 days to evaluate the survival, exposed to soil for 56 days to assess the reproductive success and for 28 days to identify the cytotoxicity. Results showed that the earthworm survival rate decreased with increasing the concentration of either deltamethrin or fenvalerate in both filter paper test and soil test. No worms survived at 602.15 μg cm(-2) of deltamethrin and 0.86 μg cm(-2) of fenvalerate in the filter paper test, however 100-125 mg kg(-1) of both chemicals resulted in the maximum mortality of 90% in the soil test. The CYP3A4 enzyme activity responded significantly to deltamethrin and fenvalerante in soil at low concentration levels, however, the toxicity response of worms under the long-term exposure conflicted with the degradation of deltamethrin and fenvalerate in soil, indicating the possible formation of more toxic pyrethroid metabolites. This study gave an insight into the toxicological effects profile of pyrethroids for a better risk assessment of pyrethroids deltamethrin and fenvalerante in soil. Copyright © 2015 Elsevier B.V. All rights reserved.

Computational Modeling of Blood Flow in the TrapEase Inferior Vena Cava Filter

DOE Office of Scientific and Technical Information (OSTI.GOV)

Singer, M A; Henshaw, W D; Wang, S L

To evaluate the flow hemodynamics of the TrapEase vena cava filter using three dimensional computational fluid dynamics, including simulated thrombi of multiple shapes, sizes, and trapping positions. The study was performed to identify potential areas of recirculation and stagnation and areas in which trapped thrombi may influence intrafilter thrombosis. Computer models of the TrapEase filter, thrombi (volumes ranging from 0.25mL to 2mL, 3 different shapes), and a 23mm diameter cava were constructed. The hemodynamics of steady-state flow at Reynolds number 600 was examined for the unoccluded and partially occluded filter. Axial velocity contours and wall shear stresses were computed. Flowmore » in the unoccluded TrapEase filter experienced minimal disruption, except near the superior and inferior tips where low velocity flow was observed. For spherical thrombi in the superior trapping position, stagnant and recirculating flow was observed downstream of the thrombus; the volume of stagnant flow and the peak wall shear stress increased monotonically with thrombus volume. For inferiorly trapped spherical thrombi, marked disruption to the flow was observed along the cava wall ipsilateral to the thrombus and in the interior of the filter. Spherically shaped thrombus produced a lower peak wall shear stress than conically shaped thrombus and a larger peak stress than ellipsoidal thrombus. We have designed and constructed a computer model of the flow hemodynamics of the TrapEase IVC filter with varying shapes, sizes, and positions of thrombi. The computer model offers several advantages over in vitro techniques including: improved resolution, ease of evaluating different thrombus sizes and shapes, and easy adaptation for new filter designs and flow parameters. Results from the model also support a previously reported finding from photochromic experiments that suggest the inferior trapping position of the TrapEase IVC filter leads to an intra-filter region of recirculating/stagnant flow with very low shear stress that may be thrombogenic.« less

Development of a nanofiltration method for bone collagen 14C AMS dating

NASA Astrophysics Data System (ADS)

Boudin, Mathieu; Boeckx, Pascal; Buekenhoudt, Anita; Vandenabeele, Peter; Van Strydonck, Mark

2013-01-01

Radiocarbon dating of bones is usually performed on the collagen fraction. However, this collagen can contain exogenous molecules, including humic substances (HSs) and/or other soil components that may have a different age than the bone. Incomplete removal can result in biased 14C dates. Ultrafiltration of collagen, dissolved as gelatin (molecular weight (MW) ∼100,000 Dalton), has received considerable attention to obtain more reliable dates. Ultrafiltration is an effective method of removal of low-molecular weight contaminants from bone collagen but it does not remove high-molecular weight contaminants, such as cross-linked humic collagen complexes. However, comparative dating studies have raised the question whether this cleaning step itself may introduce contamination with carbon from the filters used. In this study, a nanofiltration method was developed using a ceramic filter to avoid a possible extraneous carbon contamination introduced by the filter. This method should be applicable to various protein materials e.g. collagen, silk, wool, leather and should be able to remove low-molecular and high molecular weight HSs. In this study bone collagen was hot acid hydrolyzed to amino acids and nanofiltrated. A filter with a molecular weight cutoff (MWCO) of 450 Dalton was chosen in order to collect the amino acids in the permeate and the HSs in the retentate. Two pilot studies were set up. Two nanofiltration types were tested in pilot study 1: dead end and cross flow filtration. Humic substance (HS)-solutions with fossil carbon and modern hydrolyzed collagen contaminated with HSs were filtrated and analyzed with spectrofluorescence to determine the HS removal. Cross flow nanofiltration showed the most efficient HS removal. A second pilot study based upon these results was set up wherein only cross flow filtration was performed. 14C measurements of the permeates of hydrolyzed modern collagen contaminated with fossil HSs demonstrate a significant but incomplete removal of HSs (between 63% and 85%).

Leachate Geochemical Results for Ash and Burned Soil Samples from the October 2007 Southern California Wildfires

USGS Publications Warehouse

Hageman, Philip L.; Plumlee, Geoffrey S.; Martin, Deborah A.; Hoefen, Todd M.; Meeker, Gregory P.; Adams, Monique; Lamothe, Paul J.; Anthony, Michael W.

2008-01-01

This report is the second release of leachate geochemical data included as part of a multidisciplinary study of ash and burned soil samples from the October 2007 wildfires in southern California. Geochemical data for the first set of samples were released in an Open-File Report (Plumlee and others, 2007). This study is a continuation of that work. The objectives of this leaching study are to aid in understanding the interactions of ash and burned soil with rainfall. For this study, 12 samples collected in early November 2007 were leached using the U.S. Geological Survey (USGS) Field Leach Test (FLT). Following leaching, sub-samples of the leachate were analyzed for pH and specific conductance. The leachate was then filtered, and aliquots were preserved for geochemical analysis. This report presents leachate geochemical data for pH, specific conductance, alkalinity, anions using ion chromatography (I.C.), cations using inductively coupled plasma?atomic mass spectrometry (ICP-MS), and mercury by continuous flow injection?cold vapor?atomic fluorescence (CVAFS).

Impacts of different types of measurements on estimating unsaturated flow parameters

NASA Astrophysics Data System (ADS)

Shi, Liangsheng; Song, Xuehang; Tong, Juxiu; Zhu, Yan; Zhang, Qiuru

2015-05-01

This paper assesses the value of different types of measurements for estimating soil hydraulic parameters. A numerical method based on ensemble Kalman filter (EnKF) is presented to solely or jointly assimilate point-scale soil water head data, point-scale soil water content data, surface soil water content data and groundwater level data. This study investigates the performance of EnKF under different types of data, the potential worth contained in these data, and the factors that may affect estimation accuracy. Results show that for all types of data, smaller measurements errors lead to faster convergence to the true values. Higher accuracy measurements are required to improve the parameter estimation if a large number of unknown parameters need to be identified simultaneously. The data worth implied by the surface soil water content data and groundwater level data is prone to corruption by a deviated initial guess. Surface soil moisture data are capable of identifying soil hydraulic parameters for the top layers, but exert less or no influence on deeper layers especially when estimating multiple parameters simultaneously. Groundwater level is one type of valuable information to infer the soil hydraulic parameters. However, based on the approach used in this study, the estimates from groundwater level data may suffer severe degradation if a large number of parameters must be identified. Combined use of two or more types of data is helpful to improve the parameter estimation.

Examination of mercury and organic carbon dynamics from a constructed fen in the Athabasca oil sands region, Alberta, Canada using in situ and laboratory fluorescence measurements

NASA Astrophysics Data System (ADS)

Oswald, C.; Carey, S. K.

2013-12-01

In the Athabasca oil sands region, mined landscapes must be reclaimed to a functioning natural ecosystem as part of the mine closure process. To test wetland construction techniques on oil sands tailings, 55 ha of mined landscape on the Syncrude Canada Ltd. property is being reclaimed to a watershed containing a graminoid fen. The 18 ha constructed fen consists of an approximately 50 cm thick peat-mineral soil layer separated from underlying tailings sand by a thin layer of clay till. The water table in the fen is maintained by pumping water into the fen from a nearby lake and controlling outflow with under-drains. The objective of this study was to assess total mercury (THg) and methyl mercury (MeHg) concentration dynamics in water exported from the fen in relation to organic carbon quantity and composition. Water quality data from summer 2012 when the fen pumps were first turned on show that dissolved organic carbon (DOC) concentrations are on average twice as high in water flowing through the underlying tailings sand aquifer (median: 42.0 mg/L) compared to DOC concentrations in water flowing through the fen peat package (median: 20.3 mg/L). Given these DOC concentrations, filtered THg concentrations are very low (median values are 0.81 ng/L and 0.17 ng/L for water flowing through the fen peat and sand tailings, respectively) compared to concentrations reported for other boreal wetlands. Although a relationship was identified between filtered THg and DOC (r2=0.60), its slope (0.06 ng Hg/mg C) is an order-of-magnitude smaller than the typical range of slopes found at other wetland sites potentially suggesting a small pool of mercury in the peat and/or limited partitioning of mercury into solution. Filtered MeHg concentrations in all water samples are near the limit of detection and suggest that biogeochemical conditions conducive to methylation did not exist in the fen peat or tailings sand at the time of sampling. In addition to these baseline THg and MeHg results that will be used to assess the evolution of mercury dynamics in the fen as the hydrology and vegetation become established, we are investigating the composition of dissolved organic matter (DOM) using optical techniques in the water flowing through the fen peat and underlying tailing sand aquifer. During 2013, continuous in situ measurements of chromophoric DOM fluorescence (FDOM) were measured at the fen outlet to identify sources of C and their relative contribution to discharge waters. We compare these field measurements to laboratory measurements of FDOM on discrete water samples using a benchtop spectrofluorometer to develop relationships between FDOM, DOC and filtered THg and MeHg. The use of continuous in situ FDOM measurements as a proxy for DOC and mercury concentrations will improve our understanding of the effects of hydrologic management and natural seasonal variations in fen hydrology on DOC and Hg fluxes from different soil layers in the constructed system. Furthermore, we expect that the modeling of excitation-emission matrices using parallel factor analysis on discrete water samples will provide important information on the sources and reactivity of organic carbon being transported through different soil compartments in the fen.

DEMONSTRATION BULLETIN: COLLOID POLISHING FILTER METHOD - FILTER FLOW TECHNOLOGY, INC.

EPA Science Inventory

The Filter Flow Technology, Inc. (FFT) Colloid Polishing Filter Method (CPFM) was tested as a transportable, trailer mounted, system that uses sorption and chemical complexing phenomena to remove heavy metals and nontritium radionuclides from water. Contaminated waters can be pro...

Method of producing monolithic ceramic cross-flow filter

DOEpatents

Larsen, D.A.; Bacchi, D.P.; Connors, T.F.; Collins, E.L. III

1998-02-10

Ceramic filter of various configuration have been used to filter particulates from hot gases exhausted from coal-fired systems. Prior ceramic cross-flow filters have been favored over other types, but those previously have been assemblies of parts somehow fastened together and consequently subject often to distortion or delamination on exposure hot gas in normal use. The present new monolithic, seamless, cross-flow ceramic filters, being of one-piece construction, are not prone to such failure. Further, these new products are made by a novel casting process which involves the key steps of demolding the ceramic filter green body so that none of the fragile inner walls of the filter is cracked or broken. 2 figs.

Method of producing monolithic ceramic cross-flow filter

DOEpatents

Larsen, David A.; Bacchi, David P.; Connors, Timothy F.; Collins, III, Edwin L.

1998-01-01

Ceramic filter of various configuration have been used to filter particulates from hot gases exhausted from coal-fired systems. Prior ceramic cross-flow filters have been favored over other types, but those previously horn have been assemblies of parts somehow fastened together and consequently subject often to distortion or delamination on exposure hot gas in normal use. The present new monolithic, seamless, cross-flow ceramic filters, being of one-piece construction, are not prone to such failure. Further, these new products are made by novel casting process which involves the key steps of demolding the ceramic filter green body so that none of the fragile inner walls of the filter is cracked or broken.

Preferential Flow and Transport of Cryptosporidium Parvum Oocysts Through Vadose Zone: Experiments and Modeling

NASA Astrophysics Data System (ADS)

Darnault, C. J.; Darnault, C. J.; Garnier, P.; Kim, Y.; Oveson, K.; Jenkins, M.; Ghiorse, W.; Baveye, P.; Parlange, J.; Steenhuis, T.

2001-12-01

Oocysts of the protozoan Cryptosporidium parvum, when they contaminate drinking water supplies, can cause outbreaks of Cryptosporidiosis, a common waterborne disease. Of the different pathways by which oocysts can wind up in drinking water, one has received very little attention to date; because soils are often considered to be perfect filters, the transport of oocysts through the subsoil to groundwater by preferential flow is generally ignored. To evaluate its significance, three set of laboratory experiments investigated transport of oocysts through vadose zone. Experiment set I was carried out in a vertical 50 cm-long column filled with silica sand, under conditions known to foster fingered flow. Experiment set II investigates the effect of gas-water interfaces by modifying the hydrodynamical conditions in the sand columns with water-repellent sand barriers. Experiment III involved undisturbed soil columns subjected to macropores flow. The sand and soil columns were subjected to artificial rainfall and were allowed to reach steady-state. At that point, feces of contaminated calves were applied at the surface, along with a known amount of KCl to serve as tracer, and rainfall was continued at the same rate. The breakthrough of oocysts and Cl-, monitored in the effluent, demonstrate the importance of preferential flow - fingered flow and macropore flow - on the transport of oocysts through vadose zone. Peak oocyst concentrations were not appreciably delayed, compared to Cl-, and in some cases, occurred even before the Cl- peak. However, the numbers of oocysts present in the effluents were still orders of magnitude higher than the 5 to 10 oocysts per liter that are considerable sufficient to cause cryptosporidiosis in healthy adults. The transport of oocysts was simulated based on a partitioning the soil profile in both a distribution zone and a preferential zone, In particular, the model simulates accurately the markedly asymmetric breakthrough patterns, and the long exponential tailing. The spatial distribution of oocysts suggest a close relationship between oocyst retention and the extent of gas-water interfaces; sharp increases in oocyst numbers are consistently observed in regions of the sand where the water content has steep gradients, and therefore where one expects capillary meniscii to have maximal extent. These observations imply that oocyst transport in the vadose zone is likely to be very limited in the absence of preferential flow. However, experimental results suggest that the transport of oocysts in the subsurface via preferential flow may create a significant risk of groundwater contamination in some situations.

SITE TECHNOLOGY CAPSULE: FILTER FLOW TECHNOLOGY, INC. - COLLOID POLISHING FILTER METHOD

EPA Science Inventory

The Filter Flow Technology, Inc. (FFT) Coloid Polishing Filter Method (CPFM) was demonstrated at the U.S Department of Energy's (DOE) Rock Flats Plant (RFP) as part of the U.S. Environmental Protection Agency's (EPA) Superfund and Innovative Technology Evaluation (SITE) program. ...

Visualization of flow during cleaning process on a liquid nanofibrous filter

NASA Astrophysics Data System (ADS)

Bílek, P.

2017-10-01

This paper deals with visualization of flow during cleaning process on a nanofibrous filter. Cleaning of a filter is very important part of the filtration process which extends lifetime of the filter and improve filtration properties. Cleaning is carried out on flat-sheet filters, where particles are deposited on the filter surface and form a filtration cake. The cleaning process dislodges the deposited filtration cake, which is loose from the membrane surface to the retentate flow. The blocked pores in the filter are opened again and hydrodynamic properties are restored. The presented optical method enables to see flow behaviour in a thin laser sheet on the inlet side of a tested filter during the cleaning process. The local concentration of solid particles is possible to estimate and achieve new information about the cleaning process. In the article is described the cleaning process on nanofibrous membranes for waste water treatment. The hydrodynamic data were compared to the images of the cleaning process.

Kalman filters for assimilating near-surface observations into the Richards equation - Part 2: A dual filter approach for simultaneous retrieval of states and parameters

NASA Astrophysics Data System (ADS)

Medina, H.; Romano, N.; Chirico, G. B.

2014-07-01

This study presents a dual Kalman filter (DSUKF - dual standard-unscented Kalman filter) for retrieving states and parameters controlling the soil water dynamics in a homogeneous soil column, by assimilating near-surface state observations. The DSUKF couples a standard Kalman filter for retrieving the states of a linear solver of the Richards equation, and an unscented Kalman filter for retrieving the parameters of the soil hydraulic functions, which are defined according to the van Genuchten-Mualem closed-form model. The accuracy and the computational expense of the DSUKF are compared with those of the dual ensemble Kalman filter (DEnKF) implemented with a nonlinear solver of the Richards equation. Both the DSUKF and the DEnKF are applied with two alternative state-space formulations of the Richards equation, respectively differentiated by the type of variable employed for representing the states: either the soil water content (θ) or the soil water matric pressure head (h). The comparison analyses are conducted with reference to synthetic time series of the true states, noise corrupted observations, and synthetic time series of the meteorological forcing. The performance of the retrieval algorithms are examined accounting for the effects exerted on the output by the input parameters, the observation depth and assimilation frequency, as well as by the relationship between retrieved states and assimilated variables. The uncertainty of the states retrieved with DSUKF is considerably reduced, for any initial wrong parameterization, with similar accuracy but less computational effort than the DEnKF, when this is implemented with ensembles of 25 members. For ensemble sizes of the same order of those involved in the DSUKF, the DEnKF fails to provide reliable posterior estimates of states and parameters. The retrieval performance of the soil hydraulic parameters is strongly affected by several factors, such as the initial guess of the unknown parameters, the wet or dry range of the retrieved states, the boundary conditions, as well as the form (h-based or θ-based) of the state-space formulation. Several analyses are reported to show that the identifiability of the saturated hydraulic conductivity is hindered by the strong correlation with other parameters of the soil hydraulic functions defined according to the van Genuchten-Mualem closed-form model.

Divergence Free High Order Filter Methods for Multiscale Non-ideal MHD Flows

NASA Technical Reports Server (NTRS)

Yee, H. C.; Sjoegreen, Bjoern

2003-01-01

Low-dissipative high order filter finite difference methods for long time wave propagation of shock/turbulence/combustion compressible viscous MHD flows has been constructed. Several variants of the filter approach that cater to different flow types are proposed. These filters provide a natural and efficient way for the minimization of the divergence of the magnetic field (Delta . B) numerical error in the sense that no standard divergence cleaning is required. For certain 2-D MHD test problems, divergence free preservation of the magnetic fields of these filter schemes has been achieved.

Soil as the Central Link in the Hydrological Cycle

NASA Astrophysics Data System (ADS)

Hillel, D.

2005-05-01

We present an overview of the function fulfilled by the soil in the chain of processes constituting the hydrological cycle in the terrestrial domain. Considering the height of the atmosphere, the thickness of the earth's rock mantle, and the depth of the ocean, we note that the soil is amazingly thin -- typically not much more than one meter thick. Yet, with its sponge-like porosity, internal surface area, and finite capacities to absorb, store, and transmit water and solutes, the soil determines the fate of precipitation reaching the ground surface - whether it flows over the land as runoff, is detained and made available to plant roots, or seeps downward to an aquifer. Without the soil as a buffer, rainfall would produce violent floods rather than sustained stream-flow. The soil also acts as a living filter, in which dissolved and suspended constituents are retained or transmuted into nutrients for the continual regeneration of life. Energy as well as matter is in constant flux as solar radiation is absorbed by the soil and growing plants and as heat is exchanged in evaporation and condensation as well as in biochemical reactions. Plant leaves absorb carbon dioxide from the air and synthesize it with soil-derived water to form the primary compounds of life, while oxygen emitted by the leaves makes the air breathable for animals, which in turn fertilize the plants. However unique in form and function, the soil is not an isolated body but interacts with the overlying atmosphere and underlying strata, and with surface and underground bodies of water. Especially important is the interrelation between the soil and the climate, enhancing or mitigating the greenhouse effect via the soil's uptake or release of radiatively active gases (carbon dioxide, methane, and nitrous oxide). For all these reasons, it is vital that we give full consideration to the soil's role in the context of hydrology. The problem to overcome, however, is the disjunct between the characteristic spatial scales of the two disciplines. Whereas hydrology typically operates on the watershed level, traditional soil science has dealt with phenomena on the scale of a vertical profile or a restricted field. Recent efforts to define soil processes in a catenary sequence in the landscape and concurrent efforts to define the spatial variability of soil properties offer a way to close the gap and thus integrate the sister sciences.

Syringe Pump Performance Maintained with IV Filter Use During Low Flow Rate Delivery for Pediatric Patients.

PubMed

Chau, Destiny F; Vasilopoulos, Terrie; Schoepf, Miriam; Zhang, Christina; Fahy, Brenda G

2016-09-01

Complex surgical and critically ill pediatric patients rely on syringe infusion pumps for precise delivery of IV medications. Low flow rates and in-line IV filter use may affect drug delivery. To determine the effects of an in-line filter to remove air and/or contaminants on syringe pump performance at low flow rates, we compared the measured rates with the programmed flow rates with and without in-line IV filters. Standardized IV infusion assemblies with and without IV filters (filter and control groups) attached to a 10-mL syringe were primed and then loaded onto a syringe pump and connected to a 16-gauge, 16-cm single-lumen catheter. The catheter was suspended in a normal saline fluid column to simulate the back pressure from central venous circulation. The delivered infusate was measured by gravimetric methods at predetermined time intervals, and flow rate was calculated. Experimental trials for initial programmed rates of 1.0, 0.8, 0.6, and 0.4 mL/h were performed in control and filter groups. For each trial, the flow rate was changed to double the initial flow rate and was then returned to the initial flow rate to analyze pump performance for titration of rates often required during medication administration. These conditions (initial rate, doubling of initial rate, and return to initial rate) were analyzed separately for steady-state flow rate and time to steady state, whereas their average was used for percent deviation analysis. Differences between control and filter groups were assessed using Student t tests with adjustment for multiplicity (using n = 3 replications per group). Mean time from 0 to initial flow (startup delay) was <1 minute in both groups with no statistical difference between groups (P = 1.0). The average time to reach steady-state flow after infusion startup or rate changes was not statistically different between the groups (range, 0.8-5.5 minutes), for any flow rate or part of the trial (initial rate, doubling of initial rate, and return to initial rate), although the study was underpowered to detect small time differences. Overall, the mean steady-state flow rate for each trial was below the programmed flow rate with negative mean percent deviations for each trial. In the 1.0-mL/h initial rate trial, the steady-state flow rate attained was lower in the filter than the control group for the initial rate (P = 0.04) and doubling of initial rate (P = 0.04) with a trend during the return to initial rate (P = 0.06), although this same effect was not observed when doubling the initial rate trials of 0.8 or 0.6 mL/h or any other rate trials compared with the control group. With low flow rates used in complex surgical and pediatric critically ill patients, the addition of IV filters did not confer statistically significant changes in startup delay, flow variability, or time to reach steady-state flow of medications administered by syringe infusion pumps. The overall flow rate was lower than programmed flow rate with or without a filter.

Model tests of living brush mattresses made of shrub and tree willows as bank protection at navigable waters

NASA Astrophysics Data System (ADS)

Sokopp, Manuel

2014-05-01

The embankment stability at navigable waters suffers from hydraulic loads, like strong ship induced waves, resulting hydropeaking and strong water-level fluctuations. Willow brush mattresses can reduce erosion at the embankments of rivers and increase bank stability. Due to experiences gained in the project "Alternative Technical-Biological Bank Protection on Inland Water-ways" the Federal Waterways Engineering and Research Institute commissioned a more detailed investigation of protective functions of willow brush mattresses respectively the differences between brush mattresses made of pure shrub (Salix viminalis) or tree willows (Salix alba) at water ways with high ship-induced hydraulic loads. This paper shows the upcoming research methods of the years 2014 to 2016. The protective functions of two different willow brush mattresses and the congruence between soil, hydraulics and willow sprouts movement will be investigated in a wave basin by measuring flow velocity with ADVs (Acoustic Doppler Velocimeters) installed near the soil surface and in different embankment areas, the pore water pressure with probes in different soil layers, the wave height with ultrasound probes and the willow movements with permanently installed cameras while flooding the basin as well as measuring the erosion afterwards. These flooding test series will be conducted two times during the vegetation period. The shear strength of the tree willow rooted soil will be examined in different soil layers with a shear load frame. The results will be compared with the data of shear strength tests of same aged brush mattresses made of shrub willows, which have already been carried out by the Federal Waterways Engineering and Research Institute. The filtering capability of the soil covering branches and the near surface willow roots will be investigated by growing willow brush mattresses in sample boxes. Those can be repeatedly moved up and down into a diving pool while measuring pore water pressure in different soil layers and flow velocity with ADVs.

Soil porosity correlation and its influence in percolation dynamics

NASA Astrophysics Data System (ADS)

Rodriguez, Alfredo; Capa-Morocho, Mirian; Ruis-Ramos, Margarita; Tarquis, Ana M.

2016-04-01

The prediction of percolation in natural soils is relevant for modeling root growth and optimizing infiltration of water and nutrients. Also, it would improve our understanding on how pollutants as pesticides, and virus and bacteria (Darnault et al., 2003) reach significant depths without being filtered out by the soil matrix (Beven and Germann, 2013). Random walk algorithms have been used successfully to date to characterize the dynamical characteristics of disordered media. This approach has been used here to describe how soil at different bulk densities and with different threshold values applied to the 3D gray images influences the structure of the pore network and their implications on particle flow and distribution (Ruiz-Ramos et al., 2009). In order to do so first we applied several threshold values to each image analyzed and characterized them through Hurst exponents, then we computed random walks algorithms to calculate distances reached by the particles and speed of those particles. At the same time, 3D structures with a Hurst exponent of ca 0.5 and with different porosities were constructed and the same random walks simulations were replicated over these generated structures. We have found a relationship between Hurst exponents and the speed distribution of the particles reaching percolation of the total soil depth. REFERENCES Darnault, C.J. G., P. Garnier, Y.J. Kim, K.L. Oveson, T.S. Steenhuis, J.Y. Parlange, M. Jenkins, W.C. Ghiorse, and P. Baveye (2003), Preferential transport of Cryptosporidium parvum oocysts in variably saturated subsurface environments, Water Environ. Res., 75, 113-120. Beven, Keith and Germann, Peter. 2013. Macropores and water flow in soils revisited. Water Resources Research, 49(6), 3071-3092. DOI: 10.1002/wrcr.20156. Ruiz-Ramos, M., D. del Valle, D. Grinev, and A.M. Tarquis. 2009. Soil hydraulic behaviour at different bulk densities. Geophysical Research Abstracts, 11, EGU2009-6234.

Angle only tracking with particle flow filters

NASA Astrophysics Data System (ADS)

Daum, Fred; Huang, Jim

2011-09-01

We show the results of numerical experiments for tracking ballistic missiles using only angle measurements. We compare the performance of an extended Kalman filter with a new nonlinear filter using particle flow to compute Bayes' rule. For certain difficult geometries, the particle flow filter is an order of magnitude more accurate than the EKF. Angle only tracking is of interest in several different sensors; for example, passive optics and radars in which range and Doppler data are spoiled by jamming.

Similar Processes but Different Environmental Filters for Soil Bacterial and Fungal Community Composition Turnover on a Broad Spatial Scale

PubMed Central

Chemidlin Prévost-Bouré, Nicolas; Dequiedt, Samuel; Thioulouse, Jean; Lelièvre, Mélanie; Saby, Nicolas P. A.; Jolivet, Claudy; Arrouays, Dominique; Plassart, Pierre; Lemanceau, Philippe; Ranjard, Lionel

2014-01-01

Spatial scaling of microorganisms has been demonstrated over the last decade. However, the processes and environmental filters shaping soil microbial community structure on a broad spatial scale still need to be refined and ranked. Here, we compared bacterial and fungal community composition turnovers through a biogeographical approach on the same soil sampling design at a broad spatial scale (area range: 13300 to 31000 km2): i) to examine their spatial structuring; ii) to investigate the relative importance of environmental selection and spatial autocorrelation in determining their community composition turnover; and iii) to identify and rank the relevant environmental filters and scales involved in their spatial variations. Molecular fingerprinting of soil bacterial and fungal communities was performed on 413 soils from four French regions of contrasting environmental heterogeneity (Landes

Similar processes but different environmental filters for soil bacterial and fungal community composition turnover on a broad spatial scale.

PubMed

Chemidlin Prévost-Bouré, Nicolas; Dequiedt, Samuel; Thioulouse, Jean; Lelièvre, Mélanie; Saby, Nicolas P A; Jolivet, Claudy; Arrouays, Dominique; Plassart, Pierre; Lemanceau, Philippe; Ranjard, Lionel

2014-01-01

Spatial scaling of microorganisms has been demonstrated over the last decade. However, the processes and environmental filters shaping soil microbial community structure on a broad spatial scale still need to be refined and ranked. Here, we compared bacterial and fungal community composition turnovers through a biogeographical approach on the same soil sampling design at a broad spatial scale (area range: 13300 to 31000 km2): i) to examine their spatial structuring; ii) to investigate the relative importance of environmental selection and spatial autocorrelation in determining their community composition turnover; and iii) to identify and rank the relevant environmental filters and scales involved in their spatial variations. Molecular fingerprinting of soil bacterial and fungal communities was performed on 413 soils from four French regions of contrasting environmental heterogeneity (Landes

Pulsatility index variations using two different transit-time flowmeters in coronary artery bypass surgery.

PubMed

Nordgaard, Håvard B; Vitale, Nicola; Astudillo, Rafael; Renzulli, Attilio; Romundstad, Pål; Haaverstad, Rune

2010-05-01

Transit-time flow measurement is widely accepted as an intra-operative assessment in coronary artery bypass grafting (CABG). However, the two most commonly applied flowmeters, manufactured by MediStim ASA and Transonic Inc., have different default filter settings of 20 and 10 Hz, respectively. This may cause different flow measurements, which will influence the reported results. The aim was to compare pulsatility index (PI) values recorded by the MediStim and Transonic flowmeters in two different clinical settings: (1) analysis of the flow patterns recorded simultaneously by both flowmeters in the same CABGs; and (2) evaluation of flow patterns under different levels of filter settings in the same grafts. Graft flow and PI were measured using the two different flowmeters simultaneously in 19 bypass grafts. Finally, eight grafts were assessed under different digital filter settings at 5, 10, 20, 30, 50 and 100 Hz. The Transonic flowmeter provided substantially lower PI as compared with the MediStim flowmeter. By increasing the filter setting in the flowmeter, PI increased considerably. The Transonic flowmeter displayed a lower PI than the MediStim, due to a lower filter setting. In the Transonic,flow signals are filtered at a lower level, rendering a 'smoother' pattern of flow curves. Because different filter settings determine different PIs, caution must be taken when flow values and flowmeters are compared. The type of flowmeter should be indicated whenever graft flow measurements and derived indexes are provided [corrected]. Copyright 2009 European Association for Cardio-Thoracic Surgery. All rights reserved.

Adaptive Low Dissipative High Order Filter Methods for Multiscale MHD Flows

NASA Technical Reports Server (NTRS)

Yee, H. C.; Sjoegreen, Bjoern

2004-01-01

Adaptive low-dissipative high order filter finite difference methods for long time wave propagation of shock/turbulence/combustion compressible viscous MHD flows has been constructed. Several variants of the filter approach that cater to different flow types are proposed. These filters provide a natural and efficient way for the minimization of the divergence of the magnetic field [divergence of B] numerical error in the sense that no standard divergence cleaning is required. For certain 2-D MHD test problems, divergence free preservation of the magnetic fields of these filter schemes has been achieved.

Multisource data assimilation in a Richards equation-based integrated hydrological model: a real-world application to an experimental hillslope

NASA Astrophysics Data System (ADS)

Camporese, M.; Botto, A.

2017-12-01

Data assimilation is becoming increasingly popular in hydrological and earth system modeling, as it allows for direct integration of multisource observation data in modeling predictions and uncertainty reduction. For this reason, data assimilation has been recently the focus of much attention also for integrated surface-subsurface hydrological models, whereby multiple terrestrial compartments (e.g., snow cover, surface water, groundwater) are solved simultaneously, in an attempt to tackle environmental problems in a holistic approach. Recent examples include the joint assimilation of water table, soil moisture, and river discharge measurements in catchment models of coupled surface-subsurface flow using the ensemble Kalman filter (EnKF). Although the EnKF has been specifically developed to deal with nonlinear models, integrated hydrological models based on the Richards equation still represent a challenge, due to strong nonlinearities that may significantly affect the filter performance. Thus, more studies are needed to investigate the capabilities of EnKF to correct the system state and identify parameters in cases where the unsaturated zone dynamics are dominant. Here, the model CATHY (CATchment HYdrology) is applied to reproduce the hydrological dynamics observed in an experimental hillslope, equipped with tensiometers, water content reflectometer probes, and tipping bucket flow gages to monitor the hillslope response to a series of artificial rainfall events. We assimilate pressure head, soil moisture, and subsurface outflow with EnKF in a number of assimilation scenarios and discuss the challenges, issues, and tradeoffs arising from the assimilation of multisource data in a real-world test case, with particular focus on the capability of DA to update the subsurface parameters.

Environmental Filtering Process Has More Important Roles than Dispersal Limitation in Shaping Large-Scale Prokaryotic Beta Diversity Patterns of Grassland Soils.

PubMed

Cao, Peng; Wang, Jun-Tao; Hu, Hang-Wei; Zheng, Yuan-Ming; Ge, Yuan; Shen, Ju-Pei; He, Ji-Zheng

2016-07-01

Despite the utmost importance of microorganisms in maintaining ecosystem functioning and their ubiquitous distribution, our knowledge of the large-scale pattern of microbial diversity is limited, particularly in grassland soils. In this study, the microbial communities of 99 soil samples spanning over 3000 km across grassland ecosystems in northern China were investigated using high-throughput sequencing to analyze the beta diversity pattern and the underlying ecological processes. The microbial communities were dominated by Proteobacteria, Actinobacteria, Acidobacteria, Chloroflexi, and Planctomycetes across all the soil samples. Spearman's correlation analysis indicated that climatic factors and soil pH were significantly correlated with the dominant microbial taxa, while soil microbial richness was positively linked to annual precipitation. The environmental divergence-dissimilarity relationship was significantly positive, suggesting the importance of environmental filtering processes in shaping soil microbial communities. Structural equation modeling found that the deterministic process played a more important role than the stochastic process on the pattern of soil microbial beta diversity, which supported the predictions of niche theory. Partial mantel test analysis have showed that the contribution of independent environmental variables has a significant effect on beta diversity, while independent spatial distance has no such relationship, confirming that the deterministic process was dominant in structuring soil microbial communities. Overall, environmental filtering process has more important roles than dispersal limitation in shaping microbial beta diversity patterns in the grassland soils.

Assessment of existing roadside swales with engineered filter soil: I. Characterization and lifetime expectancy.

PubMed

Ingvertsen, Simon T; Cederkvist, Karin; Régent, Yoann; Sommer, Harald; Magid, Jakob; Jensen, Marina B

2012-01-01

Roadside infiltration swales with well-defined soil mixtures (filter soil) for the enhancement of both infiltration and treatment of stormwater runoff from roads and parking areas have been common practice in Germany for approximately two decades. Although the systems have proven hydraulically effective, their treatment efficiency and thus lifetime expectancies are not sufficiently documented. The lack of documentation restricts the implementation of new such systems in Germany as well as other countries. This study provides an assessment of eight roadside infiltration swales with filter soil from different locations in Germany that have been operational for 6 to16 yr. The swales were assessed with respect to visual appearance, infiltration rate, soil pH, and soil texture, as well as soil concentration of organic matter, heavy metals (Cd, Cr, Cu, Pb, Zn), and phosphorus. Visually, the swales appeared highly variable with respect to soil color and textural layering as well as composition of plants and soil-dwelling organisms. Three swales still comply with the German design criteria for infiltration rate (10 m/s), while the remaining swales have lower, yet acceptable, infiltration rates around 10 m/s. Six of the eight studied soils have heavy metal concentrations exceeding the limit value for unpolluted soil. Provided that the systems are able to continuously retain existing and incoming pollutants, our analysis indicates that the soils can remain operational for another 13 to 136 yr if the German limit values for unrestricted usage in open construction works are applied. However, no official guidelines exist for acceptable soil quality in existing infiltration facilities. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

Characterizing mercury concentrations and fluxes in a Coastal Plain watershed: Insights from dynamic modeling and data

USGS Publications Warehouse

Golden, H.E.; Knightes, C.D.; Conrads, P.A.; Davis, G.M.; Feaster, T.D.; Journey, C.A.; Benedict, S.T.; Brigham, M.E.; Bradley, P.M.

2012-01-01

Mercury (Hg) is one of the leading water quality concerns in surface waters of the United States. Although watershed-scale Hg cycling research has increased in the past two decades, advances in modeling watershed Hg processes in diverse physiographic regions, spatial scales, and land cover types are needed. The goal of this study was to assess Hg cycling in a Coastal Plain system using concentrations and fluxes estimated by multiple watershed-scale models with distinct mathematical frameworks reflecting different system dynamics. We simulated total mercury (HgT, the sum of filtered and particulate forms) concentrations and fluxes from a Coastal Plain watershed (McTier Creek) using three watershed Hg models and an empirical load model. Model output was compared with observed in-stream HgT. We found that shallow subsurface flow is a potentially important transport mechanism of particulate HgT during periods when connectivity between the uplands and surface waters is maximized. Other processes (e.g., stream bank erosion, sediment re-suspension) may increase particulate HgT in the water column. Simulations and data suggest that variable source area (VSA) flow and lack of rainfall interactions with surface soil horizons result in increased dissolved HgT concentrations unrelated to DOC mobilization following precipitation events. Although flushing of DOC-HgT complexes from surface soils can also occur during this period, DOC-complexed HgT becomes more important during base flow conditions. TOPLOAD simulations highlight saturated subsurface flow as a primary driver of daily HgT loadings, but shallow subsurface flow is important for HgT loads during high-flow events. Results suggest limited seasonal trends in HgT dynamics.

Characterizing mercury concentrations and fluxes in a Coastal Plain watershed: Insights from dynamic modeling and data

USGS Publications Warehouse

Golden, H.E.; Knightes, C.D.; Conrads, P.A.; Davis, G.M.; Feaster, T.D.; Journey, C.A.; Benedict, S.T.; Brigham, M.E.; Bradley, P.M.

2012-01-01

Mercury (Hg) is one of the leading water quality concerns in surface waters of the United States. Although watershed-scale Hg cycling research has increased in the past two decades, advances in modeling watershed Hg processes in diverse physiographic regions, spatial scales, and land cover types are needed. The goal of this study was to assess Hg cycling in a Coastal Plain system using concentrations and fluxes estimated by multiple watershed-scale models with distinct mathematical frameworks reflecting different system dynamics. We simulated total mercury (Hg T, the sum of filtered and particulate forms) concentrations and fluxes from a Coastal Plain watershed (McTier Creek) using three watershed Hg models and an empirical load model. Model output was compared with observed in-stream Hg T. We found that shallow subsurface flow is a potentially important transport mechanism of particulate Hg T during periods when connectivity between the uplands and surface waters is maximized. Other processes (e.g., stream bank erosion, sediment re-suspension) may increase particulate Hg T in the water column. Simulations and data suggest that variable source area (VSA) flow and lack of rainfall interactions with surface soil horizons result in increased dissolved Hg T concentrations unrelated to DOC mobilization following precipitation events. Although flushing of DOC-Hg T complexes from surface soils can also occur during this period, DOC-complexed Hg T becomes more important during base flow conditions. TOPLOAD simulations highlight saturated subsurface flow as a primary driver of daily Hg T loadings, but shallow subsurface flow is important for Hg T loads during high-flow events. Results suggest limited seasonal trends in Hg T dynamics. Copyright 2012 by the American Geophysical Union.

[Design Method Analysis and Performance Comparison of Wall Filter for Ultrasound Color Flow Imaging].

PubMed

Wang, Lutao; Xiao, Jun; Chai, Hua

2015-08-01

The successful suppression of clutter arising from stationary or slowly moving tissue is one of the key issues in medical ultrasound color blood imaging. Remaining clutter may cause bias in the mean blood frequency estimation and results in a potentially misleading description of blood-flow. In this paper, based on the principle of general wall-filter, the design process of three classes of filters, infinitely impulse response with projection initialization (Prj-IIR), polynomials regression (Pol-Reg), and eigen-based filters are previewed and analyzed. The performance of the filters was assessed by calculating the bias and variance of a mean blood velocity using a standard autocorrelation estimator. Simulation results show that the performance of Pol-Reg filter is similar to Prj-IIR filters. Both of them can offer accurate estimation of mean blood flow speed under steady clutter conditions, and the clutter rejection ability can be enhanced by increasing the ensemble size of Doppler vector. Eigen-based filters can effectively remove the non-stationary clutter component, and further improve the estimation accuracy for low speed blood flow signals. There is also no significant increase in computation complexity for eigen-based filters when the ensemble size is less than 10.

The effect of vegetation and soil texture on the nature of organics in runoff from a catchment supplying water for domestic consumption.

PubMed

Awad, John; van Leeuwen, John; Abate, Dawit; Pichler, Markus; Bestland, Erick; Chittleborough, David J; Fleming, Nigel; Cohen, Jonathan; Liffner, Joel; Drikas, Mary

2015-10-01

The influence of vegetation and soil texture on the concentration and character of dissolved organic matter (DOM) present in runoff from the surface and sub-surface of zero order catchments of the Myponga Reservoir-catchment (South Australia) was investigated to determine the impacts of catchment characteristics and land management practices on the quality of waters used for domestic supply. Catchments selected have distinct vegetative cover (grass, native vegetation or pine) and contrasting texture of the surface soil horizon (sand or clay loam/clay). Water samples were collected from three slope positions (upper, middle, and lower) at soil depths of ~30 cm and ~60 cm in addition to overland flows. Filtered (0.45 μm) water samples were analyzed for dissolved organic carbon (DOC) and UV-visible absorbance and by F-EEM and HPSEC with UV and fluorescence detection to characterize the DOM. Surface and sub-surface runoff from catchments with clay soils and native vegetation or grass had lower DOC concentrations and lower relative abundances of aromatic, humic-like and high molecular weight organics than runoff from sandy soils with these vegetative types. Sub-surface flows from two catchments with Pinus radiata had similar DOC concentrations and DOM character, regardless of marked variation in surface soil texture. Runoff from catchments under native vegetation and grass on clay soils resulted in lower DOC concentrations and hence would be expected to have lower coagulant demand in conventional treatment for potable water supply than runoff from corresponding sandy soil catchments. However, organics in runoff from clay catchments would be more difficult to remove by coagulation. Surface waters from the native vegetation and grass catchments were generally found to have higher relative abundance of organic compounds amenable to removal by coagulation compared with sub-surface waters. Biophysical and land management practices combine to have a marked influence on the quality of source water used for domestic supply. Copyright © 2015 Elsevier B.V. All rights reserved.

Evolution of an Interfacial Crack on the Concrete Embankment Boundary

NASA Astrophysics Data System (ADS)

Smith, J.; Ezzedine, S. M.; Lomov, I.; Kanarska, Y.; Antoun, T.; Glascoe, L. G.; Hall, R. L.; Woodson, S. C.

2013-12-01

Failure of a dam can have subtle beginnings: a small crack or dislocation at the interface of the concrete dam and the surrounding embankment soil initiated by a seismic event, for example, can: a) result in creating gaps between the concrete dam and the lateral embankments; b) initiate internal erosion of embankment; and c) lead to a catastrophic failure of the dam. The dam may ';self-rehabilitate' if a properly designed granular filter is engineered around the embankment. Currently, the design criteria for such filters have only been based on experimental studies. We demonstrate the numerical prediction of filter effectiveness at the soil grain scale and relate it to the larger dam scale. Validated computer predictions highlight that a resilient (or durable) filter is consistent with the current design specifications for dam filters. These predictive simulations, unlike the design specifications, can be used to assess filter success or failure under different soil or loading conditions and can lead to meaningful estimates of the timing and nature of full-scale dam failure. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344 and was sponsored by the Department of Homeland Security (DHS), Science and Technology Directorate, Homeland Security Advanced Research Projects Agency (HSARPA).

Rapid Radiochemical Analyses in Support of Fukushima Nuclear Accident - 13196

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maxwell, Sherrod L.; Culligan, Brian K.; Hutchison, Jay B.

There is an increasing need to develop faster analytical methods for emergency response, including emergency soil and air filter samples [1, 2]. The Savannah River National Laboratory (SRNL) performed analyses on samples received from Japan in April, 2011 as part of a U.S. Department of Energy effort to provide assistance to the government of Japan, following the nuclear event at Fukushima Daiichi, resulting from the earthquake and tsunami on March 11, 2011. Of particular concern was whether it was safe to plant rice in certain areas (prefectures) near Fukushima. The primary objectives of the sample collection, sample analysis, and datamore » assessment teams were to evaluate personnel exposure hazards, identify the nuclear power plant radiological source term and plume deposition, and assist the government of Japan in assessing any environmental and agricultural impacts associated with the nuclear event. SRNL analyzed approximately 250 samples and reported approximately 500 analytical method determinations. Samples included soil from farmland surrounding the Fukushima reactors and air monitoring samples of national interest, including those collected at the U.S. Embassy and American military bases. Samples were analyzed for a wide range of radionuclides, including strontium-89, strontium-90, gamma-emitting radionuclides, and plutonium, uranium, americium and curium isotopes. Technical aspects of the rapid soil and air filter analyses will be described. The extent of radiostrontium contamination was a significant concern. For {sup 89,90}Sr analyses on soil samples, a rapid fusion technique using 1.5 gram soil aliquots to enable a Minimum Detectable Activity (MDA) of <1 pCi {sup 89,90}Sr /g of soil was employed. This sequential technique has been published recently by this laboratory for actinides and radiostrontium in soil and vegetation [3, 4]. It consists of a rapid sodium hydroxide fusion, pre-concentration steps using iron hydroxide and calcium fluoride precipitations, followed by Sr-Resin separation and gas flow proportional counting. To achieve a lower detection limit for analysis of some of the Japanese soil samples, a 10 gram aliquot of soil was taken, acid-leached and processed with similar preconcentration chemistry. The MDA using this approach was ∼0.03 pCi/g (1.1 mBq/g)/, which is less than the 0.05-0.10 pCi/g {sup 90}Sr levels found in soil as a result of global fallout. The chemical yields observed for the Japanese soil samples was typically 75-80% and the laboratory control sample (LCS) and matrix spike (MS) results looked very good for this work Individual QC results were well within the ± 25% acceptable range and the average of these results does not show significant bias. Additional data for a radiostrontium in soil method for 50 gram samples will also be presented, which appears to be a significant step forward based on looking at the current literature, with higher chemical yields for even larger sample aliquots and lower MDA [5, 6, 7] Hou et al surveyed a wide range of separation methods for Pu in waters and environmental solid samples [8]. While there are many actinide methods in the scientific literature, few would be considered rapid due to the tedious and time-consuming steps involved. For actinide analyses in soil, a new rapid method for the determination of actinide isotopes in soil samples using both alpha spectrometry and inductively-coupled plasma mass spectrometry was employed. The new rapid soil method utilizes an acid leaching method, iron/titanium hydroxide precipitation, a lanthanum fluoride soil matrix removal step, and a rapid column separation process with TEVA Resin. The large soil matrix is removed easily and rapidly using these two simple precipitations with high chemical recoveries and effective removal of interferences. [9, 10] Vacuum box technology and rapid flow rates were used to reduce analytical time. Challenges associated with the mineral content in the volcanic soil will be discussed. Air filter samples were reported within twenty-four (24) hours of receipt using rapid techniques published previously. [11] The rapid reporting of high quality analytical data arranged through the U.S. Department of Energy Consequence Management Home Team was critical to allow the government of Japan to readily evaluate radiological impacts from the nuclear reactor incident to both personnel and the environment. SRNL employed unique rapid methods capability for radionuclides to support Japan that can also be applied to environmental, bioassay and waste management samples. New rapid radiochemical techniques for radionuclides in soil and other environmental matrices as well as some of the unique challenges associated with this work will be presented that can be used for application to environmental monitoring, environmental remediation, decommissioning and decontamination activities. (authors)« less

RAPID RADIOCHEMICAL ANALYSES IN SUPPORT OF FUKUSHIMA NUCLEAR ACCIDENT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maxwell, S.

2012-11-07

There is an increasing need to develop faster analytical methods for emergency response, including emergency soil and air filter samples. The Savannah River National Laboratory (SRNL) performed analyses on samples received from Japan in April, 2011 as part of a U.S. Department of Energy effort to provide assistance to the government of Japan, following the nuclear event at Fukushima Daiichi, resulting from the earthquake and tsunami on March 11, 2011. Of particular concern was whether it was safe to plant rice in certain areas (prefectures) near Fukushima. The primary objectives of the sample collection, sample analysis, and data assessment teamsmore » were to evaluate personnel exposure hazards, identify the nuclear power plant radiological source term and plume deposition, and assist the government of Japan in assessing any environmental and agricultural impacts associated with the nuclear event. SRNL analyzed approximately 250 samples and reported approximately 500 analytical method determinations. Samples included soil from farmland surrounding the Fukushima reactors and air monitoring samples of national interest, including those collected at the U.S. Embassy and American military bases. Samples were analyzed for a wide range of radionuclides, including strontium-89, strontium-90, gamma-emitting radionuclides, and plutonium, uranium, americium and curium isotopes. Technical aspects of the rapid soil and air filter analyses will be described. The extent of radiostrontium contamination was a significant concern. For {sup 89,90}Sr analyses on soil samples, a rapid fusion technique using 1.5 gram soil aliquots to enable a Minimum Detectable Activity (MDA) of <1 pCi {sup 89,90} Sr /g of soil was employed. This sequential technique has been published recently by this laboratory for actinides and radiostrontium in soil and vegetation. It consists of a rapid sodium hydroxide fusion, pre-concentration steps using iron hydroxide and calcium fluoride precipitations, followed by Sr-Resin separation and gas flow proportional counting. To achieve a lower detection limit for analysis of some of the Japanese soil samples, a 10 gram aliquot of soil was taken, acid-leached and processed with similar preconcentration chemistry. The MDA using this approach was ~0.03 pCi/g (1.1 mBq/g)/, which is less than the 0.05-0.10 pCi/g {sup 90}Sr levels found in soil as a result of global fallout. The chemical yields observed for the Japanese soil samples was typically 75-80% and the laboratory control sample (LCS) and matrix spike (MS) results looked very good for this work Individual QC results were well within the ± 25% acceptable range and the average of these results does not show significant bias. Additional data for a radiostrontium in soil method for 50 gram samples will also be presented, which appears to be a significant step forward based on looking at the current literature, with higher chemical yields for even larger sample aliquots and lower MDA. Hou et al surveyed a wide range of separation methods for Pu in waters and environmental solid samples. While there are many actinide methods in the scientific literature, few would be considered rapid due to the tedious and time-consuming steps involved. For actinide analyses in soil, a new rapid method for the determination of actinide isotopes in soil samples using both alpha spectrometry and inductively-coupled plasma mass spectrometry was employed. The new rapid soil method utilizes an acid leaching method, iron/titanium hydroxide precipitation, a lanthanum fluoride soil matrix removal step, and a rapid column separation process with TEVA Resin. The large soil matrix is removed easily and rapidly using these two simple precipitations with high chemical recoveries and effective removal of interferences. Vacuum box technology and rapid flow rates were used to reduce analytical time. Challenges associated with the mineral content in the volcanic soil will be discussed. Air filter samples were reported within twenty-four (24) hours of receipt using rapid techniques published previously. The rapid reporting of high quality analytical data arranged through the U.S. Department of Energy Consequence Management Home Team was critical to allow the government of Japan to readily evaluate radiological impacts from the nuclear reactor incident to both personnel and the environment. SRNL employed unique rapid methods capability for radionuclides to support Japan that can also be applied to environmental, bioassay and waste management samples. New rapid radiochemical techniques for radionuclides in soil and other environmental matrices as well as some of the unique challenges associated with this work will be presented that can be used for application to environmental monitoring, environmental remediation, decommissioning and decontamination activities.« less

Shielded regeneration heating element for a particulate filter

DOEpatents

Gonze, Eugene V [Pinckney, MI; Ament, Frank [Troy, MI

2011-01-04

An exhaust system includes a particulate filter (PF) that is disposed downstream from an engine. The PF filters particulates within an exhaust from the engine. A heating element heats particulate matter in the PF. A catalyst substrate or a flow converter is disposed upstream from said heating element. The catalyst substrate oxidizes the exhaust prior to reception by the heating element. The flow converter converts turbulent exhaust flow to laminar exhaust flow prior to reception by the heating element.

[Simulation of cropland soil moisture based on an ensemble Kalman filter].

PubMed

Liu, Zhao; Zhou, Yan-Lian; Ju, Wei-Min; Gao, Ping

2011-11-01

By using an ensemble Kalman filter (EnKF) to assimilate the observed soil moisture data, the modified boreal ecosystem productivity simulator (BEPS) model was adopted to simulate the dynamics of soil moisture in winter wheat root zones at Xuzhou Agro-meteorological Station, Jiangsu Province of China during the growth seasons in 2000-2004. After the assimilation of observed data, the determination coefficient, root mean square error, and average absolute error of simulated soil moisture were in the ranges of 0.626-0.943, 0.018-0.042, and 0.021-0.041, respectively, with the simulation precision improved significantly, as compared with that before assimilation, indicating the applicability of data assimilation in improving the simulation of soil moisture. The experimental results at single point showed that the errors in the forcing data and observations and the frequency and soil depth of the assimilation of observed data all had obvious effects on the simulated soil moisture.

A lysimeter-based approach to quantify the impact of climate change on soil hydrological processes

NASA Astrophysics Data System (ADS)

Slawitsch, Veronika; Steffen, Birk; Herndl, Markus

2016-04-01

The predicted climate change involving increasing CO2 concentrations and increasing temperatures will have effects on both vegetation and soil properties and thus on the soil water balance. The aim of this work is to quantify the effects of changes in these climatic factors on soil hydrological processes and parameters. For this purpose data of six high precision weighable lysimeters will be used. The lysimeters are part of a Lysi-T-FACE concept, where free-air will be enriched with CO2 (FACE-Technique) and infrared heaters heat the plots for investigation on effects of increasing temperatures (T-FACE-Technique). The Lysi-T-FACE concept was developed on the „Clim Grass Site" at the HBLFA Raumberg-Gumpenstein (Styria, Austria) in 2011 and 2012 with a total of 54 experimental plots. These include six plots with lysimeters where the two climatic factors are varied in different combinations. On the basis of these grass land lysimeters the soil hydraulic parameters under different experimental conditions will be investigated. The lysimeters are equipped with TDR-Trime sensors and temperature sensors combined with tensiometers in different depths. In addition, a mechanical separation snow cover system is implemented to obtain a correct water balance in winter. To be able to infer differences between the lysimeters reliably a verification of functionalities and a plausibility check of the data from the lysimeters as well as adequate data corrections are needed. Both an automatic and a user-defined control including the recently developed filter method AWAT (Adaptive Window and Adaptive Threshold Filter) are combined with a visualisation tool using the software NI DIAdem. For each lysimeter the raw data is classified in groups of matric potentials, soil water contents and lysimeter weights. Values exceeding technical thresholds are eliminated and marked automatically. The manual data control is employed every day to obtain high precision seepage water weights. The subsequent application of the AWAT Filter reduces up to 80% of the oscillations in the calculated precipitation and evapotranspiration. The filtered data of the reference plot in June 2014 yields a precipitation of about 100 mm, whereas the non-filtered raw data result in approximately 170 mm and thus an obvious overestimation of precipitation. The resulting evapotranspiration amounts to slightly more than 100 mm with filter and 200 mm without filter in the same time period. The total water balance (precipitation minus evapotranspiration) of the year 2014 obtained with the automatic and manual data filter is 470 mm on the reference plot but only 358 mm on a plot where CO2 is enriched and temperature increased. In summary, these first results demonstrate that an adequate data correction is the precondition to identify changes of soil hydrological processes and properties.

Development and verification of a new wind speed forecasting system using an ensemble Kalman filter data assimilation technique in a fully coupled hydrologic and atmospheric model

NASA Astrophysics Data System (ADS)

Williams, John L.; Maxwell, Reed M.; Monache, Luca Delle

2013-12-01

Wind power is rapidly gaining prominence as a major source of renewable energy. Harnessing this promising energy source is challenging because of the chaotic nature of wind and its inherently intermittent nature. Accurate forecasting tools are critical to support the integration of wind energy into power grids and to maximize its impact on renewable energy portfolios. We have adapted the Data Assimilation Research Testbed (DART), a community software facility which includes the ensemble Kalman filter (EnKF) algorithm, to expand our capability to use observational data to improve forecasts produced with a fully coupled hydrologic and atmospheric modeling system, the ParFlow (PF) hydrologic model and the Weather Research and Forecasting (WRF) mesoscale atmospheric model, coupled via mass and energy fluxes across the land surface, and resulting in the PF.WRF model. Numerous studies have shown that soil moisture distribution and land surface vegetative processes profoundly influence atmospheric boundary layer development and weather processes on local and regional scales. We have used the PF.WRF model to explore the connections between the land surface and the atmosphere in terms of land surface energy flux partitioning and coupled variable fields including hydraulic conductivity, soil moisture, and wind speed and demonstrated that reductions in uncertainty in these coupled fields realized through assimilation of soil moisture observations propagate through the hydrologic and atmospheric system. The sensitivities found in this study will enable further studies to optimize observation strategies to maximize the utility of the PF.WRF-DART forecasting system.

[Method for concentration determination of mineral-oil fog in the air of workplace].

PubMed

Xu, Min; Zhang, Yu-Zeng; Liu, Shi-Feng

2008-05-01

To study the method of concentration determination of mineral-oil fog in the air of workplace. Four filter films such as synthetic fabric filter film, beta glass fiber filter film, chronic filter paper and microporous film were used in this study. Two kinds of dust samplers were used to collect the sample, one sampling at fast flow rate in a short time and the other sampling at slow flow rate with long duration. Subsequently, the filter membrane was weighed with electronic analytical balance. According to sampling efficiency and incremental size, the adsorbent ability of four different filter membranes was compared. When the flow rate was between 10 approximately 20 L/min and the sampling time was between 10 approximately 15 min, the average sampling efficiency of synthetic fabric filter film was 95.61% and the increased weight ranged from 0.87 to 2.60 mg. When the flow rate was between 10 approximately 20 L/min and sampling time was between 10 approximately 15 min, the average sampling efficiency of beta glass fiber filter film was 97.57% and the increased weight was 0.75 approximately 2.47 mg. When the flow rate was between 5 approximately 10 L/min and the sampling time between 10 approximately 20 min, the average sampling efficiency of chronic filter paper and microporous film was 48.94% and 63.15%, respectively and the increased weight was 0.75 approximately 2.15 mg and 0.23 approximately 0.85 mg, respectively. When the flow rate was 3.5 L/min and the sampling time was between 100 approximately 166 min, the average sampling efficiency of filter film were 94.44% and 93.45%, respectively and the average increased weight was 1.28 mg for beta glass fiber filter film and 0.78 mg for beta glass fiber filter film and synthetic fabric synthetic fabric filter film. The average sampling efficiency of chronic filter paper and microporous film were 37.65% and 88.21%, respectively. The average increased weight was 4.30 mg and 1.23 mg, respectively. Sampling with synthetic fabric filter film and beta glass fiber filter film is credible, accurate, simple and feasible for determination of the concentration of mineral-oil fog in workplaces.

Stability performance and interface shear strength of geocomposite drain/soil systems

NASA Astrophysics Data System (ADS)

Othman, Maidiana; Frost, Matthew; Dixon, Neil

2018-02-01

Landfill covers are designed as impermeable caps on top of waste containment facilities after the completion of landfill operations. Geocomposite drain (GD) materials consist of a geonet or geospacer (as a drainage core) sandwiched between non-woven geotextiles that act as separators and filters. GD provides a drainage function as part of the cover system. The stability performance of landfill cover system is largely controlled by the interface shear strength mobilized between the elements of the cover. If a GD is used, the interface shear strength properties between the upper surface of the GD and the overlying soil may govern stability of the system. It is not uncommon for fine grained materials to be used as cover soils. In these cases, understanding soil softening issues at the soil interface with the non-woven geotextile is important. Such softening can be caused by capillary break behaviour and build-up of water pressures from the toe of the drain upwards into the cover soil. The interaction processes to allow water flow into a GD core through the soil-geotextile interface is very complex. This paper reports the main behaviour of in-situ interface shear strength of soil-GD using field measurements on the trial landfill cover at Bletchley, UK. The soil softening at the interface due to soaked behaviour show a reduction in interface shear strength and this aspect should be emphasized in design specifications and construction control. The results also help to increase confidence in the understanding of the implications for design of cover systems.

Velocity filtering applied to optical flow calculations

NASA Technical Reports Server (NTRS)

Barniv, Yair

1990-01-01

Optical flow is a method by which a stream of two-dimensional images obtained from a forward-looking passive sensor is used to map the three-dimensional volume in front of a moving vehicle. Passive ranging via optical flow is applied here to the helicopter obstacle-avoidance problem. Velocity filtering is used as a field-based method to determine range to all pixels in the initial image. The theoretical understanding and performance analysis of velocity filtering as applied to optical flow is expanded and experimental results are presented.

Simulation of filter strips influence on runoff and soil and nutrient losses under different rainfall patterns in a small vineyard catchment

NASA Astrophysics Data System (ADS)

Ramos, Maria C.; Benito, Carolina

2014-05-01

This work presents the analysis of the influence of filter strips on soil and water losses in a small catchment, whose main land use is grape vines. The watershed was located in the municipality of Piera (Barcelona, Spain). Other crops like olive trees, winter barley and alfalfa were also found, as well as some residential areas. Soil and water losses were simulated using the Soil and Water Assessment Tool (SWAT). The model was calibrated and validated using soil water and runoff data collected in the field during the period May 2010- May 2012. Then, the model was run for the period 2000-2011, which included years with different rainfall amounts and characteristics. Soil losses with and without that soil conservation measure was compared. The annual rainfall recorded during the analysed years ranged from 329.8 to 785 mm with different rainfall distributions within the year. Runoff rates ranged from 17 to 141 mm, which represented respectively 4.7 and 21% of total precipitation. Both extreme situations were recorded in the driest years of the series, with precipitation below the average. Soil losses ranged between 0.31 Mg/ha in the driest year and 13.9 Mg/ha, in the wettest. The simulation of soil losses with the introduction of filter strips 3m width in the vineyards resulted in a reduction of soil losses up to 68% in relation to the situation without that soil conservation measure. This soil loss decrease represented an additional nutrient loss reduction (up to 66% for N_organic, up to 64% of P_organic and between 6.5 and 40% of N_nitrate, depending on rainfall characteristics).

Results from Evaluation of Representative ASME AG-1 Section FK Radial Flow Dimple Pleated HEPA Filters Under Elevated Conditions - 12002

DOE Office of Scientific and Technical Information (OSTI.GOV)

Giffin, Paxton K.; Parsons, Michael S.; Rickert, Jaime G.

The American Society of Mechanical Engineers (ASME) has recently added Section FK establishing requirements for radial flow HEPA filters to the Code on Nuclear Air and Gas Treatment (AG-1). Section FK filters are expected to be a major element in the HEPA filtration systems across the US Department of Energy (DOE) complex. Radial flow filters have been used in Europe for some time, however a limited amount of performance evaluation data exists with respect to these new AG-1 Section FK units. In consultation with a technical working group, the Institute for Clean Energy Technology (ICET) at Mississippi State University (MSU)hasmore » evaluated a series of representative AG-1 Section FK dimple pleated radial flow HEPA filters. The effects of elevated relative humidity and temperature conditions on these filters are particularly concerning. Results from the evaluation of Section FK filters under ambient conditions have been presented at the 2011 waste management conference. Additions to the previous test stand to enable high temperature and high humidity testing, a review of the equipment used, the steps taken to characterize the new additions, and the filter test results are presented in this study. Test filters were evaluated at a volumetric flow rate of 56.6 m{sup 3}/min (2000 cfm) and were challenged under ambient conditions with Alumina, Al(OH){sub 3}, until reaching a differential pressure of 1 kPa (4 in. w.c.), at which time the filters were tested, unchallenged with aerosol, at 54 deg. C (130 deg. F) for approximately 1 hour. At the end of that hour water was sprayed near the heat source to maximize vaporization exposing the filter to an elevated relative humidity up to 95%. Collected data include differential pressure, temperature, relative humidity, and volumetric flow rate versus time. (authors)« less

Relative importance of habitat filtering and limiting similarity on species assemblages of alpine and subalpine plant communities.

PubMed

Takahashi, Koichi; Tanaka, Saeka

2016-11-01

This study examined how habitat filtering and limiting similarity affect species assemblages of alpine and subalpine plant communities along a slope gradient on Mt. Norikura in central Japan. Plant traits (plant height, individual leaf area, specific leaf area (SLA), leaf linearity, leaf nitrogen and chlorophyll concentrations) and abiotic environmental factors (elevation, slope inclination, ground surface texture, soil water, soil pH, soil nutrient concentrations of NH 4 -N and NO 3 -N) were examined. The metrics of variance, range, kurtosis and the standard deviation of neighbor distance divided by the range of traits present (SDNDr) were calculated for each plant trait to measure trait distribution patterns. Limiting similarity was detected only for chlorophyll concentration. By contrast, habitat filtering was detected for individual leaf area, SLA, leaf linearity, chlorophyll concentration. Abiotic environmental factors were summarized by the principal component analysis (PCA). The first PCA axis positively correlated with elevation and soil pH, and negatively correlated with sand cover, soil water, NH 4 -N and NO 3 -N concentrations. High values of the first PCA axis represent the wind-exposed upper slope with lower soil moisture and nutrient availabilities. Plant traits changed along the first PCA axis. Leaf area, SLA and chlorophyll concentration decreased, and leaf linearity increased with the first PCA axis. This study showed that the species assemblage of alpine and subalpine plants was determined mainly by habitat filtering, indicating that abiotic environmental factors are more important for species assemblage than interspecific competition. Therefore, only species adapting to abiotic environments can distribute to these environments.

Rigid porous filter

DOEpatents

Chiang, Ta-Kuan; Straub, Douglas L.; Dennis, Richard A.

2000-01-01

The present invention involves a porous rigid filter including a plurality of concentric filtration elements having internal flow passages and forming external flow passages there between. The present invention also involves a pressure vessel containing the filter for the removal of particulates from high pressure particulate containing gases, and further involves a method for using the filter to remove such particulates. The present filter has the advantage of requiring fewer filter elements due to the high surface area-to-volume ratio provided by the filter, requires a reduced pressure vessel size, and exhibits enhanced mechanical design properties, improved cleaning properties, configuration options, modularity and ease of fabrication.

Attenuation of runoff and chemical loads in grass filter strips at two cattle feedlots, Minnesota, 1995-98

USGS Publications Warehouse

Komor, Stephen Charles; Hansen, Donald S.

2003-01-01

Attenuation of cattle feedlot runoff in two grass-covered filter strips in Minnesota was estimated by measuring chemical loads into and out of the strips. Filter strips of the Bock and Sanborn sites were 60-m long and 20-m wide and received runoff from cattle feedlots that supported 35 and 225 cattle, respectively. Feedlot and filter-strip runoff were measured using flumes with stage sensors. Water samples were collected using automated samplers. Attenuation values were calculated from four storm-runoff events. Ground water sampled beneath and outside the filter strips indicated some infiltration losses of sulfate, chloride, and nitrogen at the Bock site where soil permeability was greater than at the Sanborn site. Chemical constituents in filter-strip runoff, and their corresponding ranges of attenuation were as follows: chemical oxygen demand, 30–81 percent; dissolved chloride, 6–79 percent; dissolved sulfate, -3–82 percent; dissolved ammonia nitrogen, 33–80 percent; suspended ammonia plus organic nitrogen, 29–85 percent; dissolved organic nitrogen, 14–75 percent; suspended phosphorus, 24–82 percent; dissolved phosphorus, 14–72 percent; and fecal coliform bacteria, 18–79 percent. The ranges seem to be affected by barriers of direct contact of the runoff water with the soil. This varies seasonally by coverage of the soil by ice in winter and vegetation in summer months. Greater attenuation values occurred in October and May when mats of wilted, flat-lying grass covered the filter strips; attenuation values were less during the summer when tall growing grass covered the filter strips.

Calibration and use of filter test facility orifice plates

NASA Astrophysics Data System (ADS)

Fain, D. E.; Selby, T. W.

1984-07-01

There are three official DOE filter test facilities. These test facilities are used by the DOE, and others, to test nuclear grade HEPA filters to provide Quality Assurance that the filters meet the required specifications. The filters are tested for both filter efficiency and pressure drop. In the test equipment, standard orifice plates are used to set the specified flow rates for the tests. There has existed a need to calibrate the orifice plates from the three facilities with a common calibration source to assure that the facilities have comparable tests. A project has been undertaken to calibrate these orifice plates. In addition to reporting the results of the calibrations of the orifice plates, the means for using the calibration results will be discussed. A comparison of the orifice discharge coefficients for the orifice plates used at the seven facilities will be given. The pros and cons for the use of mass flow or volume flow rates for testing will be discussed. It is recommended that volume flow rates be used as a more practical and comparable means of testing filters. The rationale for this recommendation will be discussed.

Agronomic benefits of biochar as a soil amendment after its use as waste water filtration medium.

PubMed

Werner, Steffen; Kätzl, Korbinian; Wichern, Marc; Buerkert, Andreas; Steiner, Christoph; Marschner, Bernd

2018-02-01

In many water-scarce countries, waste water is used for irrigation which poses a health risk to farmers and consumers. At the same time, it delivers nutrients to the farming systems. In this study, we tested the hypotheses that biochar can be used as a filter medium for waste water treatment to reduce pathogen loads. At the same time, the biochar is becoming enriched with nutrients and therefore can act as a fertilizer for soil amendment. We used biochar as a filter medium for the filtration of raw waste water and compared the agronomic effects of this "filterchar" (FC) and the untreated biochar (BC) in a greenhouse pot trial on spring wheat biomass production on an acidic sandy soil from Niger. The biochar filter showed the same removal of pathogens as a common sand filter (1.4 log units on average). We did not observe a nutrient accumulation in FC compared to untreated BC. Instead, P, Mg and K were reduced during filtration while N content remained unchanged. Nevertheless, higher biomass (Triticum L. Spp.) production in BC (+72%) and FC (+37%) treatments (20 t ha -1 ), compared with the unamended control, were found. There were no significant differences in aboveground biomass production between BC and FC. Soil available P content was increased by BC (+106%) and FC (+52%) application. Besides, mineral nitrogen content was reduced in BC treated soil and to a lesser extent when FC was used. This may be explained by reduced sorption affinity for mineral nitrogen compounds on FC surfaces. Although the nutrients provided by FC decreased, due to leaching in the filter, it still yielded higher biomass than the unamended control. Copyright © 2017 Elsevier Ltd. All rights reserved.

Determination of available phosphorus in soils by using a new extraction procedure and a flow injection amperometric system.

PubMed

Jakmunee, Jaroon; Junsomboon, Jaroon

2009-09-15

A new extraction procedure based on an off-line extraction column was proposed for extracting of available phosphorus from soils. The column was fabricated from a plastic syringe fitted at the bottom with a cotton wool and a piece of filter paper to support a soil sample. An aliquot (50 mL) of extracting solution (0.05 M HCl+0.0125 M H(2)SO(4)) was used to extract the sample under gravity flow and the eluate was collected in a polyethylene bottle. The extract was then analyzed for phosphorus contents by a simple flow injection amperometric system, employing a set of three-way solenoid valves as an injection valve. The method is based on the electrochemical reduction of 12-molybdophosphate which is produced on-line by the reaction of orthophosphate with acidic molybdate and the electrical current produced was directly proportional to the concentration of phosphate in range of 0.1-10.0 mg L(-1) PO(4)-P, with a detection limit of 0.02 mg L(-1). Relative standard for 11 replicate injections of 5 mg L(-1) PO(4)-P was 0.5%. A sample through put of 35 h(-1) was achieved, with consumption of 14 mg KCl, 10mg ammonium molybdate and 0.05 mL H(2)SO(4) per analysis. The detection system does not suffer from the interferences that are encountered in the photometric method such as colored substances, colloids, metal ions, silicate and refractive index effect (Schlieren effect). The results obtained by the column extraction procedure were well correlated with those obtained by the steady-state extraction procedure, but showed slightly higher extraction efficiency.

Contrasts between estimates of baseflow help discern multiple sources of water contributing to rivers

NASA Astrophysics Data System (ADS)

Cartwright, I.; Gilfedder, B.; Hofmann, H.

2014-01-01

This study compares baseflow estimates using chemical mass balance, local minimum methods, and recursive digital filters in the upper reaches of the Barwon River, southeast Australia. During the early stages of high-discharge events, the chemical mass balance overestimates groundwater inflows, probably due to flushing of saline water from wetlands and marshes, soils, or the unsaturated zone. Overall, however, estimates of baseflow from the local minimum and recursive digital filters are higher than those based on chemical mass balance using Cl calculated from continuous electrical conductivity measurements. Between 2001 and 2011, the baseflow contribution to the upper Barwon River calculated using chemical mass balance is between 12 and 25% of the annual discharge with a net baseflow contribution of 16% of total discharge. Recursive digital filters predict higher baseflow contributions of 19 to 52% of discharge annually with a net baseflow contribution between 2001 and 2011 of 35% of total discharge. These estimates are similar to those from the local minimum method (16 to 45% of annual discharge and 26% of total discharge). These differences most probably reflect how the different techniques characterise baseflow. The local minimum and recursive digital filters probably aggregate much of the water from delayed sources as baseflow. However, as many delayed transient water stores (such as bank return flow, floodplain storage, or interflow) are likely to be geochemically similar to surface runoff, chemical mass balance calculations aggregate them with the surface runoff component. The difference between the estimates is greatest following periods of high discharge in winter, implying that these transient stores of water feed the river for several weeks to months at that time. Cl vs. discharge variations during individual flow events also demonstrate that inflows of high-salinity older water occurs on the rising limbs of hydrographs followed by inflows of low-salinity water from the transient stores as discharge falls. The joint use of complementary techniques allows a better understanding of the different components of water that contribute to river flow, which is important for the management and protection of water resources.

Lattice Boltzmann simulations for wall-flow dynamics in porous ceramic diesel particulate filters

NASA Astrophysics Data System (ADS)

Lee, Da Young; Lee, Gi Wook; Yoon, Kyu; Chun, Byoungjin; Jung, Hyun Wook

2018-01-01

Flows through porous filter walls of wall-flow diesel particulate filter are investigated using the lattice Boltzmann method (LBM). The microscopic model of the realistic filter wall is represented by randomly overlapped arrays of solid spheres. The LB simulation results are first validated by comparison to those from previous hydrodynamic theories and constitutive models for flows in porous media with simple regular and random solid-wall configurations. We demonstrate that the newly designed randomly overlapped array structures of porous walls allow reliable and accurate simulations for the porous wall-flow dynamics in a wide range of solid volume fractions from 0.01 to about 0.8, which is beyond the maximum random packing limit of 0.625. The permeable performance of porous media is scrutinized by changing the solid volume fraction and particle Reynolds number using Darcy's law and Forchheimer's extension in the laminar flow region.

The Living Filter: Monitoring Nitrate Accumulation after 50 Years of Wastewater Irrigation

NASA Astrophysics Data System (ADS)

Hagedorn, J.

2015-12-01

As global freshwater sources decline due to environmental contamination and a growing population, more sustainable wastewater renovation techniques will need to be applied to ensure freshwater for future generations. One such example of a sustainable solution is called the Living Filter, located on the campus of Pennsylvania State University. For fifty years, Pennsylvania State University has sprayed treated wastewater onto agricultural fields and forest ecosystems, leaving natural processes to further filter the wastewater. This cyclical process is deemed sustainable because the freshwater is recycled, providing drinking water to an increasing university population and nutrients to agricultural crops, without causing major environmental catastrophes such as fish kills, eutrophication or groundwater contamination. At first glance this project seems sustainable and effective, but for how long can this setup continue without nutrient overloading and environmental contamination? To be truly declared sustainable, the hopeful answer to this question is indefinitely. Using a combination of soil core and monitoring tools, ecosystem indicators such as soil nutrient capacities, moisture levels, and soil characteristics were measured. Comparing data from the initial system installation to present data collected from soil cores showed how ecosystems changed over time. Results revealed that nitrate concentrations were elevated through the profile in all land use types, but the concentrations were below EPA threshold. Soil characteristic analysis including particle size distribution, soil elemental composition, and texture yielded inconclusive results regarding which factors control the nitrate accumulation most significantly. The nitrate depth profile findings suggest that spray irrigation at the Living Filter under the current rates of application has not caused the ultimate stage of nitrogen saturation in the spray irrigation site. Variations in land use present interesting findings about causation for differences in nitrate concentrations. From the viewpoint of nitrate accumulation and potential for environmental contamination, the Living Filter continues to serve as a viable mechanism for absorbing nutrient discharge and serving as the final stage of wastewater treatment.

Kalman filters for assimilating near-surface observations in the Richards equation - Part 2: A dual filter approach for simultaneous retrieval of states and parameters

NASA Astrophysics Data System (ADS)

Medina, H.; Romano, N.; Chirico, G. B.

2012-12-01

We present a dual Kalman Filter (KF) approach for retrieving states and parameters controlling soil water dynamics in a homogenous soil column by using near-surface state observations. The dual Kalman filter couples a standard KF algorithm for retrieving the states and an unscented KF algorithm for retrieving the parameters. We examine the performance of the dual Kalman Filter applied to two alternative state-space formulations of the Richards equation, respectively differentiated by the type of variable employed for representing the states: either the soil water content (θ) or the soil matric pressure head (h). We use a synthetic time-series series of true states and noise corrupted observations and a synthetic time-series of meteorological forcing. The performance analyses account for the effect of the input parameters, the observation depth and the assimilation frequency as well as the relationship between the retrieved states and the assimilated variables. We show that the identifiability of the parameters is strongly conditioned by several factors, such as the initial guess of the unknown parameters, the wet or dry range of the retrieved states, the boundary conditions, as well as the form (h-based or θ-based) of the state-space formulation. State identifiability is instead efficient even with a relatively coarse time-resolution of the assimilated observation. The accuracy of the retrieved states exhibits limited sensitivity to the observation depth and the assimilation frequency.

Temporal and Spatial Patterns of Preferential Flow Occurrence in the Shale Hills Catchment: From the Hillslope to the Catchment Scales

NASA Astrophysics Data System (ADS)

Liu, H.; Lin, H.

2013-12-01

Understanding temporal and spatial patterns of preferential flow (PF) occurrence is important in revealing hillslope and catchment hydrologic and biogeochemical processes. Quantitative assessment of the frequency and control of PF occurrence in the field, however, has been limited, especially at the landscape scale of hillslope and catchment. By using 5.5-years' (2007-2012) real-time soil moisture at 10 sites response to 323 precipitation events, we tested the temporal consistency of PF occurrence at the hillslope scale in the forested Shale Hills Catchment; and by using 25 additional sites with at least 1-year data (2011-2012), we evaluated the spatial patterns of PF occurrence across the catchment. To explore the potential effects of PF occurrence on catchment hydrology, wavelet analysis was performed on the recorded time series of hydrological signals (i.e., precipitation, soil moisture, catchment discharge). Considerable temporal consistence was observed in both the frequency and the main controls of PF occurrence at the hillslope scale, which was attributed largely to the statistical stability of precipitation pattern over the monitoring period and the relatively stable subsurface preferential pathways. Preferential flow tended to occur more often in response to intense rainfall events, and favored the conditions at dry hilltop or wet valley floor sites. When upscaling to the entire catchment, topographic control on the PF occurrence was amplified remarkably, leading to the identification of a subsurface PF network in the catchment. Higher frequency of PF occurrence was observed at the valley floor (average 48%), hilltop (average 46%), and swales/hillslopes near the stream (average 40%), while the hillslopes in the eastern part of the catchment were least likely to experience PF (0-20%). No clear relationship, however, was observed between terrain attributes and PF occurrence, because the initiation and persistency of PF in this catchment was controlled jointly by complex interactions among landform units, soil types, initial soil moisture, precipitation features, and season. Through the wavelet method (coherence spectrum and phase differences), dual-pore filtering effects of soil system were proven, rendering it possible to further infer characteristic properties of the underlying hydrological processes in the subsurface. We found that preferential flow dominates the catchment discharge response at short-time periods (< 3 days), while the matrix flow may dominate the discharge response at the time scales of around 10-12 days. The temporal and spatial patterns of PF occurrence revealed in this study can help advance the modeling and prediction of complex PF dynamics in this and other similar landscapes.

Taking Ecological Function Seriously: Soil Microbial Communities Can Obviate Allelopathic Effects of Released Metabolites

PubMed Central

Kaur, Surinder; Baldwin, Ian T.; Inderjit

2009-01-01

Background Allelopathy (negative, plant-plant chemical interactions) has been largely studied as an autecological process, often assuming simplistic associations between pairs of isolated species. The growth inhibition of a species in filter paper bioassay enriched with a single chemical is commonly interpreted as evidence of an allelopathic interaction, but for some of these putative examples of allelopathy, the results have not been verifiable in more natural settings with plants growing in soil. Methodology/Principal findings On the basis of filter paper bioassay, a recent study established allelopathic effects of m-tyrosine, a component of root exudates of Festuca rubra ssp. commutata. We re-examined the allelopathic effects of m-tyrosine to understand its dynamics in soil environment. Allelopathic potential of m-tyrosine with filter paper and soil (non-sterile or sterile) bioassays was studied using Lactuca sativa, Phalaris minor and Bambusa arundinacea as assay species. Experimental application of m-tyrosine to non-sterile and sterile soil revealed the impact of soil microbial communities in determining the soil concentration of m-tyrosine and growth responses. Conclusions/Significance Here, we show that the allelopathic effects of m-tyrosine, which could be seen in sterilized soil with particular plant species were significantly diminished when non-sterile soil was used, which points to an important role for rhizosphere-specific and bulk soil microbial activity in determining the outcome of this allelopathic interaction. Our data show that the amounts of m-tyrosine required for root growth inhibition were higher than what would normally be found in F. rubra ssp. commutata rhizosphere. We hope that our study will motivate researchers to integrate the role of soil microbial communities in bioassays in allelopathic research so that its importance in plant-plant competitive interactions can be thoroughly evaluated. PMID:19277112

Determining the frequency, depth and velocity of preferential flow by high frequency soil moisture monitoring

NASA Astrophysics Data System (ADS)

Hardie, Marcus; Lisson, Shaun; Doyle, Richard; Cotching, William

2013-01-01

Preferential flow in agricultural soils has been demonstrated to result in agrochemical mobilisation to shallow ground water. Land managers and environmental regulators need simple cost effective techniques for identifying soil - land use combinations in which preferential flow occurs. Existing techniques for identifying preferential flow have a range of limitations including; often being destructive, non in situ, small sampling volumes, or are subject to artificial boundary conditions. This study demonstrated that high frequency soil moisture monitoring using a multi-sensory capacitance probe mounted within a vertically rammed access tube, was able to determine the occurrence, depth, and wetting front velocity of preferential flow events following rainfall. Occurrence of preferential flow was not related to either rainfall intensity or rainfall amount, rather preferential flow occurred when antecedent soil moisture content was below 226 mm soil moisture storage (0-70 cm). Results indicate that high temporal frequency soil moisture monitoring may be used to identify soil type - land use combinations in which the presence of preferential flow increases the risk of shallow groundwater contamination by rapid transport of agrochemicals through the soil profile. However use of high frequency based soil moisture monitoring to determine agrochemical mobilisation risk may be limited by, inability to determine the volume of preferential flow, difficulty observing macropore flow at high antecedent soil moisture content, and creation of artificial voids during installation of access tubes in stony soils.

Fire modifies the phylogenetic structure of soil bacterial co-occurrence networks.

PubMed

Pérez-Valera, Eduardo; Goberna, Marta; Faust, Karoline; Raes, Jeroen; García, Carlos; Verdú, Miguel

2017-01-01

Fire alters ecosystems by changing the composition and community structure of soil microbes. The phylogenetic structure of a community provides clues about its main assembling mechanisms. While environmental filtering tends to reduce the community phylogenetic diversity by selecting for functionally (and hence phylogenetically) similar species, processes like competitive exclusion by limiting similarity tend to increase it by preventing the coexistence of functionally (and phylogenetically) similar species. We used co-occurrence networks to detect co-presence (bacteria that co-occur) or exclusion (bacteria that do not co-occur) links indicative of the ecological interactions structuring the community. We propose that inspecting the phylogenetic structure of co-presence or exclusion links allows to detect the main processes simultaneously assembling the community. We monitored a soil bacterial community after an experimental fire and found that fire altered its composition, richness and phylogenetic diversity. Both co-presence and exclusion links were more phylogenetically related than expected by chance. We interpret such a phylogenetic clustering in co-presence links as a result of environmental filtering, while that in exclusion links reflects competitive exclusion by limiting similarity. This suggests that environmental filtering and limiting similarity operate simultaneously to assemble soil bacterial communities, widening the traditional view that only environmental filtering structures bacterial communities. © 2016 Society for Applied Microbiology and John Wiley & Sons Ltd.

Filtered Rayleigh Scattering Measurements in a Buoyant Flow Field

DTIC Science & Technology

2008-03-01

ENY/08-M22 Abstract Filtered Rayleigh Scattering (FRS) is a non-intrusive, laser -based flow characterization technique that consists of a narrow...linewidth laser , a molecular absorption filter, and a high resolution camera behind the filter to record images. Gases of different species have...different molecular scattering cross-sections that become apparent as they pass through the interrogating laser light source, and this difference is

Evaluation of a Soil Moisture Data Assimilation System Over the Conterminous United States

NASA Astrophysics Data System (ADS)

Bolten, J. D.; Crow, W. T.; Zhan, X.; Reynolds, C. A.; Jackson, T. J.

2008-12-01

A data assimilation system has been designed to integrate surface soil moisture estimates from the EOS Advanced Microwave Scanning Radiometer (AMSR-E) with an online soil moisture model used by the USDA Foreign Agriculture Service for global crop estimation. USDA's International Production Assessment Division (IPAD) of the Office of Global Analysis (OGA) ingests global soil moisture within a Crop Assessment Data Retrieval and Evaluation (CADRE) Decision Support System (DSS) to provide nowcasts of crop conditions and agricultural-drought. This information is primarily used to derive mid-season crop yield estimates for the improvement of foreign market access for U.S. agricultural products. The CADRE is forced by daily meteorological observations (precipitation and temperature) provided by the Air Force Weather Agency (AFWA) and World Meteorological Organization (WMO). The integration of AMSR-E observations into the two-layer soil moisture model employed by IPAD can potentially enhance the reliability of the CADRE soil moisture estimates due to AMSR-E's improved repeat time and greater spatial coverage. Assimilation of the AMSR-E soil moisture estimates is accomplished using a 1-D Ensemble Kalman filter (EnKF) at daily time steps. A diagnostic calibration of the filter is performed using innovation statistics by accurately weighting the filter observation and modeling errors for three ranges of vegetation biomass density estimated using historical data from the Advanced Very High Resolution Radiometer (AVHRR). Assessment of the AMSR-E assimilation has been completed for a five year duration over the conterminous United States. To evaluate the ability of the filter to compensate for incorrect precipitation forcing into the model, a data denial approach is employed by comparing soil moisture results obtained from separate model simulations forced with precipitation products of varying uncertainty. An analysis of surface and root-zone anomalies is presented for each model simulation over the conterminous United States, as well as statistical assessments for each simulation over various land cover types.

Data assimilation with soil water content sensors and pedotransfer functions in soil water flow modeling

USDA-ARS?s Scientific Manuscript database

Soil water flow models are based on a set of simplified assumptions about the mechanisms, processes, and parameters of water retention and flow. That causes errors in soil water flow model predictions. Soil water content monitoring data can be used to reduce the errors in models. Data assimilation (...

Efficiency of Silver Impregnated Porous Pot (SIPP) Filters for Production of Clean Potable Water

PubMed Central

Mahlangu, Oranso; Mamba, Bhekie; Momba, Maggie

2012-01-01

The Silver Impregnated Porous Pot (SIPP) filter is a product of the Tshwane University of Technology manufactured for the production of safe drinking water at a household (home) level. Two SIPP devices were assessed for the reduction efficiency of chemical contaminants such as calcium, magnesium, iron, arsenic, fluorides and total organic carbon (TOC) as well as microbial contaminants from environmental samples. Turbidity change after filtration, together with correlation between chlorophyll a in the feed water and SIPP’s flow rates were also evaluated in order to give comprehensive guidelines on the quality of intake water that could be filtered through the filter without causing a significant decrease in flow rate. The SIPP filters removed contaminants from environmental water samples as follows: 70% to 92% iron, 36% to 68% calcium, 42% to 82% arsenic, 39% to 98% magnesium, 39% to 95% fluorides, 12% to 35% TOC and 45% to 82% turbidity. The SIPP filters had initial flow rates of 1 L/h to 4 L/h but the flow rates dropped to 0.5 L/h with an increase in cumulative volume of intake water as the filter was used. Turbidity and chemical contaminant reduction rates decreased with accumulating volume of intake water but the filter removed Ca, Fe and Mg to levels that comply with the South African National Standards (SANS 241) and the World Health Organization (WHO) guideline values. However, the SIPP filters cannot produce enough water to satisfy the daily drinking water requirement of a typical household (25 L/p·d). Chlorophyll a was associated with a decrease in the flow rate through the SIPP filters. PMID:23202668

Efficiency of Silver Impregnated Porous Pot (SIPP) filters for production of clean potable water.

PubMed

Mahlangu, Oranso; Mamba, Bhekie; Momba, Maggie

2012-08-24

The Silver Impregnated Porous Pot (SIPP) filter is a product of the Tshwane University of Technology manufactured for the production of safe drinking water at a household (home) level. Two SIPP devices were assessed for the reduction efficiency of chemical contaminants such as calcium, magnesium, iron, arsenic, fluorides and total organic carbon (TOC) as well as microbial contaminants from environmental samples. Turbidity change after filtration, together with correlation between chlorophyll a in the feed water and SIPP's flow rates were also evaluated in order to give comprehensive guidelines on the quality of intake water that could be filtered through the filter without causing a significant decrease in flow rate. The SIPP filters removed contaminants from environmental water samples as follows: 70% to 92% iron, 36% to 68% calcium, 42% to 82% arsenic, 39% to 98% magnesium, 39% to 95% fluorides, 12% to 35% TOC and 45% to 82% turbidity. The SIPP filters had initial flow rates of 1 L/h to 4 L/h but the flow rates dropped to 0.5 L/h with an increase in cumulative volume of intake water as the filter was used. Turbidity and chemical contaminant reduction rates decreased with accumulating volume of intake water but the filter removed Ca, Fe and Mg to levels that comply with the South African National Standards (SANS 241) and the World Health Organization (WHO) guideline values. However, the SIPP filters cannot produce enough water to satisfy the daily drinking water requirement of a typical household (25 L/p·d). Chlorophyll a was associated with a decrease in the flow rate through the SIPP filters.

Apparatus for real-time airborne particulate radionuclide collection and analysis

DOEpatents

Smart, John E.; Perkins, Richard W.

2001-01-01

An improved apparatus for collecting and analyzing an airborne particulate radionuclide having a filter mounted in a housing, the housing having an air inlet upstream of the filter and an air outlet downstream of the filter, wherein an air stream flows therethrough. The air inlet receives the air stream, the filter collects the airborne particulate radionuclide and permits a filtered air stream to pass through the air outlet. The improvement which permits real time counting is a gamma detecting germanium diode mounted downstream of the filter in the filtered air stream. The gamma detecting germanium diode is spaced apart from a downstream side of the filter a minimum distance for a substantially maximum counting detection while permitting substantially free air flow through the filter and uniform particulate radionuclide deposition on the filter.

Percutaneous Venous Thrombectomy Using the Arrow-Trerotola Percutaneous Thrombolytic Device (PTD) with Temporary Caval Filtration: In Vitro Investigations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wildberger, Joachim Ernst, E-mail: wildberg@rad.rwth-aachen.de; Haage, Patrick; Bovelander, Jan

2005-04-15

Purpose. To evaluate the size and quantity of downstream emboli after thrombectomy using the Arrow-Trerotola Percutaneous Thrombolytic Device (PTD) with or without temporary filtration for extensive iliofemoral and iliocaval thrombi in an in vitro flow model. Methods. Iliocaval thrombi were simulated by clotted bovine blood in a flow model (semilucent silicone tubings, diameter 12-16 mm). Five experimental set-ups were performed 10 times each; thrombus particles and distribution were measured in the effluent. First, after retrograde insertion, mechanical thrombectomy was performed using the PTD alone. Then a modified self-expanding tulip-shaped temporary vena cava stent filter was inserted additionally at the beginningmore » of each declotting procedure and removed immediately after the intervention without any manipulation within or at the filter itself. In a third step, the filter was filled with thrombus only. Here, two experiments were performed: Careful closure within the flow circuit without any additional fragmentation procedure and running the PTD within the filter lumen, respectively. In the final set-up, mechanical thrombectomy was performed within the thrombus-filled tubing as well as in the filter lumen. The latter was closed at the end of the procedure and both devices were removed from the flow circuit. Results. Running the PTD in the flow circuit without filter protection led to a fragmentation of 67.9% ({+-}7.14%) of the clot into particles {<=}500 {mu}m; restoration of flow was established in all cases. Additional placement of the filter safely allowed maceration of 82.9% ({+-}5.59%) of the thrombus. Controlled closure of the thrombus-filled filter within the flow circuit without additional mechanical treatment broke up 75.2% ({+-}10.49%), while additional mechanical thrombectomy by running the PTD within the occluded filter led to dissolution of 90.4% ({+-}3.99%) of the initial clot. In the final set-up, an overall fragmentation rate of 99.6% ({+-}0.44%) was achieved. Conclusions. The combined use of the Arrow-Trerotola PTD and a temporary vena cava stent filter proved to be effective for even large clot removal in this experimental set-up.« less

DEVELOPMENT OF A LAMINATED DISK FOR THE SPIN TEK ROTARY MICROFILTER

DOE Office of Scientific and Technical Information (OSTI.GOV)

Herman, D.

2011-06-03

Funded by the Department of Energy Office of Environmental Management, EM-31, the Savannah River National Laboratory (SRNL) partnered with SpinTek Filtration{trademark} to develop a filter disk that would withstand a reverse pressure or flow during operation of the rotary microfilter. The ability to withstand a reverse pressure and flow eliminates a potential accident scenario that could have resulted in damage to the filter membranes. While the original welded filter disks have been shown to withstand and reverse pressure/flow in the static condition, the filter disk design discussed in this report will allow a reverse pressure/flow while the disks are rotating.more » In addition, the laminated disk increases the flexibility during filter startup and cleaning operations. The new filter disk developed by SRNL and SpinTek is manufactured with a more open structure significantly reducing internal flow restrictions in the disk. The prototype was tested at the University of Maryland and demonstrated to withstand the reverse pressure due to the centrifugal action of the rotary filter. The tested water flux of the disk was demonstrated to be 1.34 gpm in a single disk test. By comparison, the water flux of the current disk was 0.49 gpm per disk during a 25 disk test. The disk also demonstrated rejection of solids by filtering a 5 wt % Strontium Carbonate slurry with a filtrate clarity of less the 1.4 Nephelometric Turbidity Units (NTU) throughout the two hour test. The Savannah River National Laboratory (SRNL) has been working with SpinTek Filtration{trademark} to adapt the rotary microfilter for radioactive service in the Department of Energy (DOE) Complex. One potential weakness is the loose nature of the membrane on the filter disks. The current disk is constructed by welding the membrane at the outer edge of the disk. The seal for the center of the membrane is accomplished by an o-ring in compression for the assembled stack. The remainder of the membrane is free floating on the disk. This construction requires that a positive pressure be applied to the rotary filter tank to prevent the membrane from rising from the disk structure and potentially contacting the filter turbulence promoter. In addition, one accident scenario is a reverse flow through the filtrate line due to mis-alignment of valves resulting in the membrane rising from the disk structure. The structural integrity of the current disk has been investigated, and shown that the disk can withstand a significant reverse pressure in a static condition. However, the disk will likely incur damage if the filter stack is rotated during a reverse pressure. The development of a laminated disk would have several significant benefits for the operation of the rotary filter including the prevention of a compromise in filter disk integrity during a reverse flow accident, increasing operational flexibility, and increasing the self cleaning ability of the filter. A laminated disk would allow the filter rotor operation prior to a positive pressure in the filter tank. This would prevent the initial dead-head of the filter and prevent the resulting initial filter cake buildup. The laminated disk would allow rotor operation with cleaning fluid, eliminating the need for a recirculation pump. Additionally, a laminated disk would allow a reverse flow of fluid through the membrane pores removing trapped particles.« less

Understanding mineral dusts from the Middle East

NASA Astrophysics Data System (ADS)

Engelbrecht, J. P.; McDonald, E.; Gillies, J. A.; Jayanty, J.; Casuccio, G.; Gertler, A.

2012-12-01

The purpose of the program was to provide scientifically founded information on the chemical and physical properties of airborne mineral dust collected during a period of approximately one year, largely in 2006, at Djibouti, Afghanistan (Bagram, Khowst), Qatar, United Arab Emirates, Iraq (Balad, Baghdad, Tallil, Tikrit, Taji, Al Asad), and Kuwait (Northern, Central, Coastal, and Southern regions). To fully understand mineral dusts, their chemical and physical properties as well as mineralogical interrelationships were accurately established. Three collocated low volume particulate samplers, one each for the total suspended (TSP), less than 10 μm in aerodynamic diameter (PM10), and less than 2.5 μm in aerodynamic diameter (PM2.5) particulate matter were deployed at each of the 15 sites, operating on a "1 in 6 day" sampling schedule. A total of 3,136 filter samples were collected on a 1-in-6 day schedule, along with one-time bulk soil samples, at each of the 15 sites. Sample media included Teflon® membrane and quartz fiber filters for chemical analysis (71 species), and Nuclepore® filters for individual particle analysis by Scanning Electron Microscopy (SEM). The provisional study of the data revealed three broad air pollution sources: geological dust, smoke from burn pits, and until now unidentified lead-zinc smelters and battery-processing facilities. SEM results and secondary electron imagery show that quartz and other silicate minerals and, to a lesser extent, dolomite and calcite particles are coated by a thin Si-Al-Mg layer, probably the clay minerals palygorskite and/or montmorillonite/illite. Positive Matrix Factorization (PMF) was performed on aerosol samples collected at six military sites in Iraq (Balad, Baghdad, Tallil, Tikrit, Taji, and Al Asad). PMF results reflect chemical differences amongst sources impacting at individual sites, further complicated by the regional geomorphology and meteorology. Sampling sites are seldom impacted by one source at a time. Also, dust palls are continually being modified by added dust from soils across which they migrate, and by particle segregation in the dust plume followed by precipitation of the coarser particles. PMF was applied separately to two ambient data sets collected in Iraq in 2006, the one on Teflon membrane filters and the other on quartz fiber. Each of the filter types were previously analyzed for different chemical species: Teflon membrane for elements, by XRF and ICP-MS, while quartz fiber filters were analyzed for ions and carbon. A set of 392 Teflon filter samples analyzed for 25 elemental species was modeled by PMF. A five factor solution identified three soil factors, a silicate soil, limestone soil, and a gypsum soil, as well as a salt factor and an anthropogenic metal factor. Similarly, a set of 362 quartz filter samples analyzed for 10 selected chemical species was modeled by PMF. A five factor solution provided a limestone-gypsum soil, diesel combustion, secondary ammonium sulfate, salt and agricultural-burnpit combustion source type.

A Global Assessment of Oceanic Heat Loss: Conductive Cooling and Hydrothermal Redistribution of Heat

NASA Astrophysics Data System (ADS)

Hasterok, D. P.; Chapman, D. S.; Davis, E. E.

2011-12-01

A new dataset of ~15000 oceanic heat flow measurements is analyzed to determine the conductive heat loss through the seafloor. Many heat flow values in seafloor younger than 60 Ma are lower than predicted by models of conductively cooled lithosphere. This heat flow deficit is caused by ventilated hydrothermal circulation discharging at crustal outcrops or through thin sedimentary cover. Globally filtering of heat flow data to retain sites with sediment cover >400 m thick and located >60 km from the nearest seamount minimizes the effect of hydrothermal ventilation. Filtered heat flow exhibit a much higher correlation coefficient with seafloor age (up to 0.95 for filtered data in contrast to 0.5 for unfiltered data) and lower variability (reduction by 30%) within an age bin. A small heat flow deficit still persists at ages <25 Ma, possibly as a result of global filtering limitations and incomplete thermal rebound following sediment burial. Detailed heat flow surveys co-located with seismic data can identify environments favoring conductive heat flow; heat flow collected in these environments is higher than that determined by the global dataset, and is more consistent with conductive cooling of the lithosphere. The new filtered data analysis and a growing number of site specific surveys both support estimates of global heat loss in the range 40-47 TW. The estimated hydrothermal deficit is consistent with estimates from geochemical studies ~7 TW, but is a few TW lower than previous estimates derived from heat flow determinations.

Phosphorus retention by fly-ash amended filter media in aged bioretention cells

USDA-ARS?s Scientific Manuscript database

Bioretention cells (BRCs) have shown potential for stormwater quantity and quality control. However, the phosphorus (P) removal in BRC has been variable due to differences of soil properties in filter media. The objectives of this research were to identify and evaluate P accumulation in filter media...

Simulation on Soot Oxidation with NO2 and O2 in a Diesel Particulate Filter

NASA Astrophysics Data System (ADS)

Yamamoto, Kazuhiro; Satake, Shingo; Yamashita, Hiroshi; Obuchi, Akira; Uchisawa, Junko

Although diesel engines have an advantage of low fuel consumption in comparison with gasoline engines, exhaust gas has more particulate matters (PM) including soot. As one of the key technologies, a diesel particulate filter (DPF) has been developed to reduce PM. When the exhaust gas passes its porous filter wall, the soot particles are trapped. However, the filter would readily be plugged with particles, and the accumulated particles must be removed to prevent filter clogging and a rise in backpressure, which is called filter regeneration process. In this study, we have simulated the flow in the wall-flow DPF using the lattice Boltzmann method. Filters of different length, porosity, and pore size are used. The soot oxidation for filter regeneration process is considered. Especially, the effect of NO2 on the soot oxidation is examined. The reaction rate has been determined by previous experimental data. Results show that, the flow along the filter monolith is roughly uniform, and the large pressure drop across the filter wall is observed. The soot oxidation rate becomes ten times larger when NO2 is added. These are useful information to construct the future regeneration system.

Accounting for the measurement error of spectroscopically inferred soil carbon data for improved precision of spatial predictions.

PubMed

Somarathna, P D S N; Minasny, Budiman; Malone, Brendan P; Stockmann, Uta; McBratney, Alex B

2018-08-01

Spatial modelling of environmental data commonly only considers spatial variability as the single source of uncertainty. In reality however, the measurement errors should also be accounted for. In recent years, infrared spectroscopy has been shown to offer low cost, yet invaluable information needed for digital soil mapping at meaningful spatial scales for land management. However, spectrally inferred soil carbon data are known to be less accurate compared to laboratory analysed measurements. This study establishes a methodology to filter out the measurement error variability by incorporating the measurement error variance in the spatial covariance structure of the model. The study was carried out in the Lower Hunter Valley, New South Wales, Australia where a combination of laboratory measured, and vis-NIR and MIR inferred topsoil and subsoil soil carbon data are available. We investigated the applicability of residual maximum likelihood (REML) and Markov Chain Monte Carlo (MCMC) simulation methods to generate parameters of the Matérn covariance function directly from the data in the presence of measurement error. The results revealed that the measurement error can be effectively filtered-out through the proposed technique. When the measurement error was filtered from the data, the prediction variance almost halved, which ultimately yielded a greater certainty in spatial predictions of soil carbon. Further, the MCMC technique was successfully used to define the posterior distribution of measurement error. This is an important outcome, as the MCMC technique can be used to estimate the measurement error if it is not explicitly quantified. Although this study dealt with soil carbon data, this method is amenable for filtering the measurement error of any kind of continuous spatial environmental data. Copyright © 2018 Elsevier B.V. All rights reserved.

NHEXAS PHASE I ARIZONA STUDY--STANDARD OPERATING PROCEDURE FOR EXTRACTION OF METALS FROM SOIL, DUST, AIR FILTER, AND SURFACE AND DERMAL SAMPLES FOR AA (GRAPHITE FURNACE OR FLAME) OR ICP-AES ANALYSIS (BCO-L-3.1)

EPA Science Inventory

The purpose of this SOP is to describe the acid digestion of soil, house dust, air filter, and surface or dermal wipe samples for analysis using inductively coupled plasma atomic emissions spectrometry (ICP-AES) and/or graphite furnace atomic absorption spectrometry (GFAAS) or fl...

Fungal colonization of air filters for use in heating, ventilating, and air conditioning (HVAC) systems.

PubMed

Simmons, R B; Crow, S A

1995-01-01

New and used cellulosic air filters for HVAC systems including those treated with antimicrobials were suspended in vessels with a range of relative humidities (55-99%) and containing non-sterile potting soil which stimulates fungal growth. Most filters yielded fungi prior to suspension in the chambers but only two of 14 nontreated filters demonstrated fungal colonization following use in HVAC systems. Filters treated with antimicrobials, particularly a phosphated amine complex, demonstrated markedly less fungal colonization than nontreated filters. In comparison with nontreated cellulosic filters, fungal colonization of antimicrobial-treated cellulosic filters was selective and delayed.

Response of Sugarcane in a Red Ultisol to Phosphorus Rates, Phosphorus Sources, and Filter Cake

PubMed Central

Prado, Renato de Mello; Campos, Cid Naudi Silva; Rosatto Moda, Leandro; de Lima Vasconcelos, Ricardo; Pizauro Júnior, João Martins

2015-01-01

We evaluated the effect of phosphorus application rates from various sources and in the presence or absence of filter cake on soil phosphorus, plant phosphorus, changes in acid phosphatase activity, and sugarcane productivity grown in Eutrophic Red Ultisol. Three P sources were used (triple superphosphate, Araxa rock phosphate, and Bayovar rock phosphate) and four application rates (0, 90, 180, and 360 kg ha−1 of P2O5) in the presence or absence of filter cake (7.5 t ha−1, dry basis). The soil P, the accumulated plant P, the leaf acid phosphatase activity and straw, the stalk productivity, the concentration of soluble solids in the juice (Brix), the juice sucrose content (Pol), and the purity were the parameters evaluated. We found that P applications increased levels of soil, leaf, and juice phosphorus and led to higher phosphorus accumulation and greater stalk and straw productivity. These levels were highest in the presence of filter cake. Acid phosphatase activity decreased with increasing plant phosphorus concentration. Phosphate fertilization did not show effect on sugarcane technological quality. We concluded that P application, regardless of source, improved phosphorus nutrition and increased productivity in sugarcane and, when associated with filter cake, reduced the need for mineral fertilizer. PMID:26078993

Analyzing the uncertainty of suspended sediment load prediction using sequential data assimilation

NASA Astrophysics Data System (ADS)

Leisenring, Marc; Moradkhani, Hamid

2012-10-01

SummaryA first step in understanding the impacts of sediment and controlling the sources of sediment is to quantify the mass loading. Since mass loading is the product of flow and concentration, the quantification of loads first requires the quantification of runoff volume. Using the National Weather Service's SNOW-17 and the Sacramento Soil Moisture Accounting (SAC-SMA) models, this study employed particle filter based Bayesian data assimilation methods to predict seasonal snow water equivalent (SWE) and runoff within a small watershed in the Lake Tahoe Basin located in California, USA. A procedure was developed to scale the variance multipliers (a.k.a hyperparameters) for model parameters and predictions based on the accuracy of the mean predictions relative to the ensemble spread. In addition, an online bias correction algorithm based on the lagged average bias was implemented to detect and correct for systematic bias in model forecasts prior to updating with the particle filter. Both of these methods significantly improved the performance of the particle filter without requiring excessively wide prediction bounds. The flow ensemble was linked to a non-linear regression model that was used to predict suspended sediment concentrations (SSCs) based on runoff rate and time of year. Runoff volumes and SSC were then combined to produce an ensemble of suspended sediment load estimates. Annual suspended sediment loads for the 5 years of simulation were finally computed along with 95% prediction intervals that account for uncertainty in both the SSC regression model and flow rate estimates. Understanding the uncertainty associated with annual suspended sediment load predictions is critical for making sound watershed management decisions aimed at maintaining the exceptional clarity of Lake Tahoe. The computational methods developed and applied in this research could assist with similar studies where it is important to quantify the predictive uncertainty of pollutant load estimates.

Visualization of dyed NAPL concentration in transparent porous media using color space components.

PubMed

Kashuk, Sina; Mercurio, Sophia R; Iskander, Magued

2014-07-01

Finding a correlation between image pixel information and non-aqueous phase liquid (NAPL) saturation is an important issue in bench-scale geo-environmental model studies that employ optical imaging techniques. Another concern is determining the best dye color and its optimum concentration as a tracer for use in mapping NAPL zones. Most bench scale flow studies employ monochromatic gray-scale imaging to analyze the concentration of mostly red dyed NAPL tracers in porous media. However, the use of grayscale utilizes a third of the available information in color images, which typically contain three color-space components. In this study, eight color spaces consisting of 24 color-space components were calibrated against dye concentration for three color-dyes. Additionally, multiple color space components were combined to increase the correlation between color-space data and dyed NAPL concentration. This work is performed to support imaging of NAPL migration in transparent synthetic soils representing the macroscopic behavior of natural soils. The transparent soil used in this study consists of fused quartz and a matched refractive index mineral-oil solution that represents the natural aquifer. The objective is to determine the best color dye concentration and ideal color space components for rendering dyed sucrose-saturated fused quartz that represents contamination of the natural aquifer by a dense NAPL (DNAPL). Calibration was achieved for six NAPL zone lengths using 3456 images (24 color space components×3 dyes×48 NAPL combinations) of contaminants within a defined criteria expressed as peak signal to noise ratio. The effect of data filtering was also considered and a convolution average filter is recommended for image conditioning. The technology presented in this paper is fast, accurate, non-intrusive and inexpensive method for quantifying contamination zones using transparent soil models. Copyright © 2014 Elsevier B.V. All rights reserved.

Influence of the lower boundary in lysimeter observations

NASA Astrophysics Data System (ADS)

Weller, Ulrich; Richter, Katja; Gubis, Jozef; Vogel, Hans-Jörg

2014-05-01

Lysimeters are a valuable tool to study the water household in soils under close to natural conditions. One major drawback is that they are cut off at the lower boundary. This influences strongly the percolation of water. As long as water is leaching down in the soil, it is stagnating at the lower boundary until saturated conditions are reached and the water can percolate through the gravel filter, and under unsaturated conditions there is no flow at all at the lower boundary. In natural soils the water potential at the same depth differs considerably from the regime in a lysimeter. If the depth of the soil or the soil forming substrate is deep enough, the lower boundary is at the potential that allows the percolation of the long term mean of percolation. In other situations, a water table may influence the matric potential in the natural soil, or a less permeable layer may impede free drainage. In all these situations the matric potential at the depth of the lower boundary of the lysimeter will differ substantially in the natural soil. The latest generation of lysimeter therefore has a controlled lower boundary. The matric potential can be actively adjusted to a desired value over a broad range. Most applications connect the suction in the lysimeter to a reference value obtained in the field at the same depth in order to mimic the correct distribution of the soil water. In this presentation we demonstrate the long term influence of the different lower boundary regimes on percolation and evaporation of water based on soil physical models, and we show first field data on the practical implementations with several months of observations.

Absorption Filter Based Optical Diagnostics in High Speed Flows

NASA Technical Reports Server (NTRS)

Samimy, Mo; Elliott, Gregory; Arnette, Stephen

1996-01-01

Two major regimes where laser light scattered by molecules or particles in a flow contains significant information about the flow are Mie scattering and Rayleigh scattering. Mie scattering is used to obtain only velocity information, while Rayleigh scattering can be used to measure both the velocity and the thermodynamic properties of the flow. Now, recently introduced (1990, 1991) absorption filter based diagnostic techniques have started a new era in flow visualization, simultaneous velocity and thermodynamic measurements, and planar velocity measurements. Using a filtered planar velocimetry (FPV) technique, we have modified the optically thick iodine filter profile of Miles, et al., and used it in the pressure-broaden regime which accommodates measurements in a wide range of velocity applications. Measuring velocity and thermodynamic properties simultaneously, using absorption filtered based Rayleigh scattering, involves not only the measurement of the Doppler shift, but also the spectral profile of the Rayleigh scattering signal. Using multiple observation angles, simultaneous measurement of one component velocity and thermodynamic properties in a supersonic jet were measured. Presently, the technique is being extended for simultaneous measurements of all three components of velocity and thermodynamic properties.

Improving wind energy forecasts using an Ensemble Kalman Filter data assimilation technique in a fully coupled hydrologic and atmospheric model

NASA Astrophysics Data System (ADS)

Williams, J. L.; Maxwell, R. M.; Delle Monache, L.

2012-12-01

Wind power is rapidly gaining prominence as a major source of renewable energy. Harnessing this promising energy source is challenging because of the chaotic nature of wind and its propensity to change speed and direction over short time scales. Accurate forecasting tools are critical to support the integration of wind energy into power grids and to maximize its impact on renewable energy portfolios. Numerous studies have shown that soil moisture distribution and land surface vegetative processes profoundly influence atmospheric boundary layer development and weather processes on local and regional scales. Using the PF.WRF model, a fully-coupled hydrologic and atmospheric model employing the ParFlow hydrologic model with the Weather Research and Forecasting model coupled via mass and energy fluxes across the land surface, we have explored the connections between the land surface and the atmosphere in terms of land surface energy flux partitioning and coupled variable fields including hydraulic conductivity, soil moisture and wind speed, and demonstrated that reductions in uncertainty in these coupled fields propagate through the hydrologic and atmospheric system. We have adapted the Data Assimilation Research Testbed (DART), an implementation of the robust Ensemble Kalman Filter data assimilation algorithm, to expand our capability to nudge forecasts produced with the PF.WRF model using observational data. Using a semi-idealized simulation domain, we examine the effects of assimilating observations of variables such as wind speed and temperature collected in the atmosphere, and land surface and subsurface observations such as soil moisture on the quality of forecast outputs. The sensitivities we find in this study will enable further studies to optimize observation collection to maximize the utility of the PF.WRF-DART forecasting system.

Fail Save Shut Off Valve for Filtering Systems Employing Candle Filters

DOEpatents

VanOsdol, John

2006-01-03

The invention relates to an apparatus that acts as a fail save shut off valve. More specifically, the invention relates to a fail save shut off valve that allows fluid flow during normal operational conditions, but prevents the flow of fluids in the event of system failure upstream that causes over-pressurization. The present invention is particularly well suited for use in conjunction with hot gas filtering systems, which utilize ceramic candle filters. Used in such a hot gas system the present invention stops the flow of hot gas and prevents any particulate laden gas from entering the clean side of the system.

Fail save shut off valve for filtering systems employing candle filters

DOEpatents

VanOsdol, John [Fairmont, WV

2006-01-03

The invention relates to an apparatus that acts as a fail save shut off valve. More specifically, the invention relates to a fail save shut off valve that allows fluid flow during normal operational conditions, but prevents the flow of fluids in the event of system failure upstream that causes over-pressurization. The present invention is particularly well suited for use in conjunction with hot gas filtering systems, which utilize ceramic candle filters. Used in such a hot gas system the present invention stops the flow of hot gas and prevents any particulate laden gas from entering the clean side of the system.

The suitability of remotely sensed soil moisture for improving operational flood forecasting

NASA Astrophysics Data System (ADS)

Wanders, N.; Karssenberg, D.; de Roo, A.; de Jong, S. M.; Bierkens, M. F. P.

2013-11-01

We evaluate the added value of assimilated remotely sensed soil moisture for the European Flood Awareness System (EFAS) and its potential to improve the prediction of the timing and height of the flood peak and low flows. EFAS is an operational flood forecasting system for Europe and uses a distributed hydrological model for flood predictions with lead times up to 10 days. For this study, satellite-derived soil moisture from ASCAT, AMSR-E and SMOS is assimilated into the EFAS system for the Upper Danube basin and results are compared to assimilation of discharge observations only. To assimilate soil moisture and discharge data into EFAS, an Ensemble Kalman Filter (EnKF) is used. Information on the spatial (cross-) correlation of the errors in the satellite products, is included to ensure optimal performance of the EnKF. For the validation, additional discharge observations not used in the EnKF, are used as an independent validation dataset. Our results show that the accuracy of flood forecasts is increased when more discharge observations are assimilated; the Mean Absolute Error (MAE) of the ensemble mean is reduced by 65%. The additional inclusion of satellite data results in a further increase of the performance: forecasts of base flows are better and the uncertainty in the overall discharge is reduced, shown by a 10% reduction in the MAE. In addition, floods are predicted with a higher accuracy and the Continuous Ranked Probability Score (CRPS) shows a performance increase of 5-10% on average, compared to assimilation of discharge only. When soil moisture data is used, the timing errors in the flood predictions are decreased especially for shorter lead times and imminent floods can be forecasted with more skill. The number of false flood alerts is reduced when more data is assimilated into the system and the best performance is achieved with the assimilation of both discharge and satellite observations. The additional gain is highest when discharge observations from both upstream and downstream areas are used in combination with the soil moisture data. These results show the potential of remotely sensed soil moisture observations to improve near-real time flood forecasting in large catchments.

Stochastic Flow Cascades

NASA Astrophysics Data System (ADS)

Eliazar, Iddo I.; Shlesinger, Michael F.

2012-01-01

We introduce and explore a Stochastic Flow Cascade (SFC) model: A general statistical model for the unidirectional flow through a tandem array of heterogeneous filters. Examples include the flow of: (i) liquid through heterogeneous porous layers; (ii) shocks through tandem shot noise systems; (iii) signals through tandem communication filters. The SFC model combines together the Langevin equation, convolution filters and moving averages, and Poissonian randomizations. A comprehensive analysis of the SFC model is carried out, yielding closed-form results. Lévy laws are shown to universally emerge from the SFC model, and characterize both heavy tailed retention times (Noah effect) and long-ranged correlations (Joseph effect).

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fred J. Molz, III

To better understand longer-term vadose zone transport in southeastern soils, field lysimeter experiments were conducted at the Savannah River Site (SRS) near Aiken, SC, in the 1980s. Each of the three lysimeters analyzed herein contained a filter paper spiked with different Pu solutions, and they were left exposed to natural environmental conditions (including the growth of annual weed grasses) for 11 years. The resulting Pu activity measurements from each lysimeter core showed anomalous activity distributions below the source, with significant migration of Pu above the source. Such results are not explainable by adsorption phenomena alone. A transient variably saturated flowmore » model with root water uptake was developed and coupled to a soil reactive transport model. Somewhat surprisingly, the fully transient analysis showed results nearly identical to those of a much simpler steady flow analysis performed previously. However, all phenomena studied were unable to produce the upward Pu transport observed in the data. This result suggests another transport mechanism such as Pu uptake by roots and upward transport due to transpiration. Thus, the variably saturated flow and reactive transport model was extended to include uptake and transport of Pu within the root xylem, along with computational methodology and results. In the extended model, flow velocity in the soil was driven by precipitation input along with transpiration and drainage. Water uptake by the roots determined the flow velocity in the root xylem, and this along with uptake of Pu in the transpiration stream drove advection and dispersion of the two Pu species in the xylem. During wet periods with high potential evapotranspiration, maximum flow velocities through the xylem would approached 600 cm/hr, orders of magnitude larger that flow velocities in the soil. Values for parameters and the correct conceptual viewpoint for Pu transport in plant xylem was uncertain. This motivated further experiments devoted to Pu uptake by corn roots and xylem transport. Plants were started in wet paper wrapped around each corn seed. When the tap roots were sufficiently long, the seedlings were transplanted to a soil container with the tap root extending out the container bottom. The soil container was then placed over a nutrient solution container, and the solution served as an additional medium for root growth. To conduct an uptake study, a radioactive substance, such as Pu complexed with the bacterial siderophore DFOB, was added to the nutrient solution. After a suitable elapsed time, the corn plant was sacrificed, cut into 10 cm lengths, and the activity distribution measured. Experimental results clarified the basic nature of Pu uptake and transport in corn plants, and resulting simulations suggested that each growing season Pu in the SRS lysimeters would move into the plant shoots and be deposited on the soil surface during the Fall dieback. Subsequent isotope ratio analyses showed that this did happen. OVERALL RESULTS AND CONCLUSIONS - (1) Pu transport downward from the source is controlled by advection, dispersion and adsorption, along with surface-mediated REDOX reactions. (2) Hysteresis, extreme root distribution functions, air-content dependent oxidation rate constants, and large evaporation rates from the soil surface were not able to explain the observed upward migration of Pu. (3) Small amounts of Pu uptake by plant roots and translocation in the transpiration stream creates a realistic mechanism for upward Pu migration (4) Realistic xylem cross-sectional areas imply high flow velocities under hot, wet conditions. Such flow velocities produce the correct shape for the observed activity distributions in the top 20 cm of the lysimeter soil. (5) Simulations imply that Pu should have moved into the above-ground grass tissue each year during the duration of the experiments, resulting in an activity residual accumulating on the soil surface. An isotope ratio analysis showed that the observed surface Pu residue was from the buried sources, not atmospheric fallout. (6) The plant experiments indicate a Pu-DFOB velocity in the corn xylem of at least 174 cm/hr, much higher than ionic Pu in soil. Thus, Pu complexation with chelating agents is probably what led to the observed enhanced uptake and mobility in grasses. (7) Plant experiments show that the uptake of Fe-DFOB, Pu-DFOB and the resulting distributions are very similar. This supports the hypothesis that plant and bacterial iron-seeking chemistry mistakes Pu for Fe.« less

Nuclear Magnetic Resonance Relaxation and Imaging Studies on Water Flow in Soil Cores

NASA Astrophysics Data System (ADS)

Pohlmeier, Andreas; Haber-Pohlmeier, Sabina; Stapf, Siegfried

2010-05-01

Magnetic resonance imaging (MRI) is applied to the study of flow processes in a model and a natural soils core. Since flow velocities in soils are mostly too slow to be monitored directly by MRI flow velocity imaging, Gd-DTPA was used as contrast agent for the first time for flow processes in soils. Apart from its chemical stability the main advantage is the anionic net charge in neutral aqueous solution. Here we can show that this property hinders the adsorption at soil mineral surfaces and therefore retardation. Gd-DTPA turns out to be a very convenient conservative tracer for the investigation of flow processes in model and natural soil cores. With respect to the flow processes in the coaxial model soil column and the natural soil column we found total different flow patterns: In the first case tracer plume moves quite homogeneously only in the inner highly conductive core. No penetration into the outer fine material takes place. In contrast, the natural soil core shows a flow pattern which is characterized by preferential paths avoiding dense regions and preferring loose structures. In the case of the simpler model column also the local flow velocities are calculated by the application of a peak tracking algorithm.

Enhancing Bioremediation of Oil-contaminated Soils by Controlling Nutrient Transport using Dual Characteristics of Soil Pore Structure

NASA Astrophysics Data System (ADS)

Mori, Y.; Suetsugu, A.; Matsumoto, Y.; Fujihara, A.; Suyama, K.; Miyamoto, T.

2012-12-01

Soil structure is heterogeneous with cracks or macropores allowing bypass flow, which may lead to applied chemicals avoiding interaction with soil particles or the contaminated area. We investigated the bioremediation efficiency of oil-contaminated soils by applying suction at the bottom of soil columns during bioremediation. Unsaturated flow conditions were investigated so as to avoid bypass flow and achieve sufficient dispersion of chemicals in the soil column. The boundary conditions at the bottom of the soil columns were 0 kPa and -3 kPa, and were applied to a volcanic ash soil with and without macropores. Unsaturated flow was achieved with -3 kPa and an injection rate of 1/10 of the saturated hydraulic conductivity. The resultant biological activities of the effluent increased dramatically in the unsaturated flow with macropores condition. Unsaturated conditions prevented bypass flow and allowed dispersion of the injected nutrients. Unsaturated flow achieved 60-80% of saturation, which enhanced biological activity in the soil column. Remediation results were better for unsaturated conditions because of higher biological activity. Moreover, unsaturated flow with macropores achieved uniform remediation efficiency from upper through lower positions in the column. Finally, taking the applied solution volume into consideration, unsaturated flow with -3 kPa achieved 10 times higher efficiency when compared with conventional saturated flow application. These results suggest that effective use of nutrients or remediation chemicals is possible by avoiding bypass flow and enhancing biological activity using relatively simple and inexpensive techniques.

Evaluation of the interaction between plant roots and preferential flow paths

NASA Astrophysics Data System (ADS)

Zhang, Yinghu; Niu, Jianzhi; Zhang, Mingxiang; Xiao, Zixing; Zhu, Weili

2017-04-01

Introduction Preferential flow causing environmental issues by carrying contaminants to the groundwater resources level, occurs throughout the world. Soil water flow and solute transportation via preferential flow paths with little resistance could bypass soil matrix quickly. It is necessary to characterize preferential flow phenomenon because of its understanding of ecological functions of soil, including the degradation of topsoil, the low activity of soil microorganisms, the loss of soil nutrients, and the serious source of pollution of groundwater resources (Brevik et al., 2015; Singh et al., 2015). Studies on the interaction between plant roots and soil water flow in response to preferential flow is promising increasingly. However, it is complicated to evaluate soil hydrology when plant roots are associated with the mechanisms of soil water flow and solute transportation, especially preferential flow (Ola et al., 2015). Root channels formed by living/decayed plant roots and root-soil interfaces affect soil hydrology (Tracy et al., 2011). For example, Jørgensen et al. (2002) stated that soil water flow was more obvious in soil profiles with plant roots than in soil profiles without plant roots. The present study was conducted to investigate the interaction between plant roots and soil water flow in response to preferential flow in stony soils. Materials and methods Field experiments: field dye tracing experiments centered on experimental plants (S. japonica Linn, P. orientalis (L.) Franco, and Q. dentata Thunb) were conducted to characterize the root length density, preferential flow paths (stained areas), and soil matrix (unstained areas). Brilliant Blue FCF (C.I. Food Blue 2) as dye solution (50 L) was applied to the experimental plots. Laboratory analyses: undisturbed soil columns (7-cm diameter, 10 cm high) obtained from soil depths of 0-20, 20-40, and 40-60 cm, respectively, were conducted with breakthrough curves experiments under different conditions maintaining (1) a constant hydraulic head of 1ṡ0 cm of water with various solution concentrations of 0ṡ5, 1ṡ0, and 1ṡ5 g L-1, and (2) a constant solution concentration of 1ṡ0 g L-1 with various hydraulic heads of 0ṡ5, 1ṡ0, and 1ṡ5 cm of water, and those columns were conducted under saturated and unsaturated soil conditions, respectively. The effluent samples were measured with an ultraviolet spectrometer subsystem to determine the relative concentration. The plant root-water interaction (PRWI) was recognized as an indicator of the influences of plant roots on soil water flow. Results Our study showed that (1) fine plant roots in preferential flow paths decreased with soil depth and was mostly recorded in the upper soil layers to a depth of 20 cm for all experimental plots. The root length density of preferential flow paths made up at least 50% of the total root length density at each soil depth; (2) preferential flow effects were most apparent on soil water flow at the 0-20-cm soil depth compared with the other depths (20-40 and 40-60 cm); (3) positive correlations between fine plant roots and the plant root-water interaction (PRWI) were observed. References Brevik EC, Cerdà A, Mataix-Solera J, Pereg L, Quinton JN, Six J, Van Oost K. 2015. The interdisciplinary nature of SOIL. SOIL 1: 117-129. DOI: 10.5194/soil-1-117-2015. Singh YP, Nayak AK, Sharma DK, Singh G, Mishra VK, Singh D. 2015. Evaluation of Jatropha curcas genotypes for rehabilitation of degraded sodic lands. Land Degradation & Development 26(5): 510-520. DOI: 10.1002/ldr.2398. Ola A, Dodd IC, Quinton JN. 2015. Can we manipulate root system architecture to control soil erosion? SOIL 1: 603-612. DOI: 10.5194/soild-2-265-2015. Tracy SR, Black CR, Roberts JA, Mooney SJ. 2011. Soil compaction: a review of past and present techniques for investigating effects on root growth. Journal of the Science of Food & Agriculture 91: 1528-1537. DOI: 10.1002/jsfa.4424. Jørgensen PR, Hoffmann M, Kistrup JP, Bryde C, Bossi R, Villholth KG. 2002. Preferential flow and pesticide transport in a clay-rich till: field, laboratory, and modeling analysis. Water Resources Research 38: 1246-1261. DOI: 10.1029/2001WR000494.

Biofiltration of solvent vapors from air

DOE Office of Scientific and Technical Information (OSTI.GOV)

Oh, Young-sook.

1993-01-01

For various industrial solvent vapors, biofiltration promises to offer a cost-effective emission control technology. Exploiting the full potential of this technology will help attain the goals of the Clean Air Act Amendments of 1990. Concentrating on large volumes of volatile industrial solvents, stable multicomponent microbial enrichments capable of growing a mineral medium with solvent vapors as their only source of carbon and energy were obtained from soil and sewage sludge. These consortia were immobilized on an optimized porous solid support (ground peat moss and perlite). The biofilter material was packed in glass columns connected to an array of pumps andmore » flow meters that allowed the independent variation of superficial velocity and solvent vapor concentrations. In various experiments, single solvents, such as methanol, butanol, acetonitrile, hexane and nitrobenzene, and solvent mixtures, such as benzene-toluene-xylene (BTX) and chlorobenzene-o-dichlorobenzene (CB/DCB) were biofiltered with rates ranging from 15 to334 g solvent removed per m[sup 3] filter volume /h. Pressure drops were low to moderate (0-10 mmHg/m) and with periodic replacement of moisture, the biofiltration activity could be maintained for a period of several months. The experimental data on methanol biofiltration were subjected to mathematical analysis and modeling by the group of Dr. Baltzis at NJIT for a better understanding and a possible scale up of solvent vapor biofilters. In the case of chlorobenzenes and nitrobenzene, the biofilter columns had to be operated with water recirculation in a trickling filter mode. To prevent inactivation of the trickling filter by acidity during CB/DCB removal, pH control was necessary, and the removal rate of CB/DCB was strongly influenced by the flow rate of the recyling water. Nitrobenzene removal in a trickling filter did not require pH control, since the nitro group was reduced and volatilized as ammonia.« less

Velocity of water flow along saturated loess slopes under erosion effects

NASA Astrophysics Data System (ADS)

Huang, Yuhan; Chen, Xiaoyan; Li, Fahu; Zhang, Jing; Lei, Tingwu; Li, Juan; Chen, Ping; Wang, Xuefeng

2018-06-01

Rainfall or snow-melted water recharge easily saturates loose top soils with a less permeable underlayer, such as cultivated soil slope and partially thawed top soil layer, and thus, may influence the velocity of water flow. This study suggested a methodology and device system to supply water from the bottom soil layer at the different locations of slopes. Water seeps into and saturates the soil, when the water level is controlled at the same height of the soil surface. The structures and functions of the device, the components, and the operational principles are described in detail. A series of laboratory experiments were conducted under slope gradients of 5°, 10°, 15°, and 20° and flow rates of 2, 4, and 8 L min-1 to measure the water flow velocities over eroding and non-eroded loess soil slopes, under saturated conditions by using electrolyte tracing. Results showed that flow velocities on saturated slopes were 17% to 88% greater than those on non-saturated slopes. Flow velocity increased rapidly under high flow rates and slope gradients. Saturation conditions were suitable in maintaining smooth rill geomorphology and causing fast water flow. The saturated soil slope had a lubricant effect on the soil surface to reduce the frictional force, resulting in high flow velocity. The flow velocities of eroding rills under different slope gradients and flow rates were approximately 14% to 33% lower than those of non-eroded rills on saturated loess slopes. Compared with that on a saturated loess slope, the eroding rill on a non-saturated loess slope can produce headcuts to reduce the flow velocity. This study helps understand the hydrodynamics of soil erosion and sediment transportation of saturated soil slopes.

Surfactant-Induced Changes of Water Flow and Solute Transport in Soils

NASA Astrophysics Data System (ADS)

Kinsey, E. N.; Korte, C.; Peng, Z.; Yu, C.; Powelson, D.; Jacobson, A. R.; Baveye, P. C.; Darnault, C. J. G.

2016-12-01

Surfactants are present in the environment due to agricultural practices such as irrigation with wastewater, biosolid soil amendments, and/or environmental engineering remediation. Furthermore, surfactants occur widely in soils due to the application of pesticides in surfactant solution sprays, or the application of surfactants as soil wetting agents. Surfactants, because they are amphiphilic and impact the surface tension of aqueous solutions and the contact angle between aqueous and solid phases have the potential to influence water flow in porous media and the physicochemical properties of soils. The objective of this study was to assess the impact of surfactant on the soil infiltration process. Four different soils were used in this study: two sandy loam soils (Lewiston and Greenson series) and two loamy sand soils (Sparta and Gilford series). Rainfall was simulated to flow through different columns filled with the four different types of soil and effluent samples were collected at the end of each column. Each type of soil had two columns, one with a non-ionic surfactant Aerosol®22 at twice the critical micelle concentration, in the rainfall solution and one without. A conservative tracer, potassium bromide, was added to all rainfalls to monitor the infiltration process in soil. Tracer breakthrough curves were used to characterize flow in soils. Flow rates were also recorded for each soil. The presence of surfactant decreased the flow rate by a significant amount in most soil types. The decrease in flow rate can be attributed to the effects on the soil properties of hydraulic conductivity and soil aggregates. A decrease in pore space from the swelling of the soil particles can decrease the hydraulic conductivity. The properties in surfactants also decrease the surface tension and therefore soil particles are able to be dislodged from soil aggregates and cause potential soil clogging.

Three Principles of Water Flow in Soils

NASA Astrophysics Data System (ADS)

Guo, L.; Lin, H.

2016-12-01

Knowledge of water flow in soils is crucial to understanding terrestrial hydrological cycle, surface energy balance, biogeochemical dynamics, ecosystem services, contaminant transport, and many other Critical Zone processes. However, due to the complex and dynamic nature of non-uniform flow, reconstruction and prediction of water flow in natural soils remain challenging. This study synthesizes three principles of water flow in soils that can improve modeling water flow in soils of various complexity. The first principle, known as the Darcy's law, came to light in the 19th century and suggested a linear relationship between water flux density and hydraulic gradient, which was modified by Buckingham for unsaturated soils. Combining mass balance and the Buckingham-Darcy's law, L.A. Richards quantitatively described soil water change with space and time, i.e., Richards equation. The second principle was proposed by L.A. Richards in the 20th century, which described the minimum pressure potential needed to overcome surface tension of fluid and initiate water flow through soil-air interface. This study extends this principle to encompass soil hydrologic phenomena related to varied interfaces and microscopic features and provides a more cohesive explanation of hysteresis, hydrophobicity, and threshold behavior when water moves through layered soils. The third principle is emerging in the 21st century, which highlights the complex and evolving flow networks embedded in heterogeneous soils. This principle is summarized as: Water moves non-uniformly in natural soils with a dual-flow regime, i.e., it follows the least-resistant or preferred paths when "pushed" (e.g., by storms) or "attracted" (e.g., by plants) or "restricted" (e.g., by bedrock), but moves diffusively into the matrix when "relaxed" (e.g., at rest) or "touched" (e.g., adsorption). The first principle is a macroscopic view of steady-state water flow, the second principle is a microscopic view of interface-based dynamics of water flow, and the third principle combines macroscopic and microscopic consideration to explain a mosaic-like flow regime in soils. Integration of above principles can advance flow theory, measurement, and modeling and can improve management of soil and water resources.

U.S.-MEXICO BORDER PROGRAM ARIZONA BORDER STUDY--STANDARD OPERATING PROCEDURE FOR EXTRACTION OF METALS FROM SOIL, DUST, AIR FILTER, AND SURFACE AND DERMAL WIPE SAMPLES FOR AA (GRAPHITE FURNACE OR FLAME) OR ICP-AES ANALYSIS (BCO-L-3.1)

EPA Science Inventory

The purpose of this SOP is to describe the acid digestion of soil, house dust, air filter, and surface or dermal wipe samples for analysis using inductively coupled plasma atomic emissions spectrometry (ICP-AES) and/or graphite furnace atomic absorption spectrometry (GFAAS) or fl...

Lander, Airbags, & Martian terrain

NASA Technical Reports Server (NTRS)

1997-01-01

Several objects have been imaged by the Imager for Mars Pathfinder (IMP) during the spacecraft's first day on Mars. Portions of the deflated airbags, part of one the lander's petals, soil, and several rocks are visible. The furrows in the soil were artificially produced by the retraction of the airbags after landing, which occurred at 10:07 a.m. PDT.

The IMP is a stereo imaging system with color capability provided by 24 selectable filters -- twelve filters per 'eye.

Radar systems for the water resources mission, volume 1

NASA Technical Reports Server (NTRS)

Moore, R. K.; Claassen, J. P.; Erickson, R. L.; Fong, R. K. T.; Hanson, B. C.; Komen, M. J.; Mcmillan, S. B.; Parashar, S. K.

1976-01-01

The state of the art determination was made for radar measurement of: soil moisture, snow, standing and flowing water, lake and river ice, determination of required spacecraft radar parameters, study of synthetic-aperture radar systems to meet these parametric requirements, and study of techniques for on-board processing of the radar data. Significant new concepts developed include the following: scanning synthetic-aperture radar to achieve wide-swath coverage; single-sideband radar; and comb-filter range-sequential, range-offset SAR processing. The state of the art in radar measurement of water resources parameters is outlined. The feasibility for immediate development of a spacecraft water resources SAR was established. Numerous candidates for the on-board processor were examined.

Eulerian Time-Domain Filtering for Spatial LES

NASA Technical Reports Server (NTRS)

Pruett, C. David

1997-01-01

Eulerian time-domain filtering seems to be appropriate for LES (large eddy simulation) of flows whose large coherent structures convect approximately at a common characteristic velocity; e.g., mixing layers, jets, and wakes. For these flows, we develop an approach to LES based on an explicit second-order digital Butterworth filter, which is applied in,the time domain in an Eulerian context. The approach is validated through a priori and a posteriori analyses of the simulated flow of a heated, subsonic, axisymmetric jet.

Remediation of PCB contaminated soils in the Canadian Arctic: excavation and surface PRB technology.

PubMed

Kalinovich, Indra; Rutter, Allison; Poland, John S; Cairns, Graham; Rowe, R Kerry

2008-12-15

The site BAF-5 is located on the summit of Resolution Island, Nunavut, just southeast of Baffin Island at 61 degrees 35'N and 60 degrees 40'W. The site was part of a North American military defense system established in the 1950s that became heavily contaminated with PCBs during and subsequent, its operational years. Remediation through excavation of the PCB contaminated soil at Resolution Island began in 1999 and at its completion in 2006 approximately 5 tonnes of pure PCBs in approximately 20,000 m3 of soil were remediated. Remediation strategies were based on both quantity of soil and level of contamination in the soil. Excavation removed 96% of the PCB contaminated soil on site. In 2003, a surface funnel-and-gate permeable reactive barrier was design and constructed to treat the remaining contamination left in rock crevices and inaccessible areas of the site. Excavation had destabilized contaminated soil in the area, enabling contaminant migration through erosion and runoff pathways. The barrier was designed to maximize sedimentation through settling ponds. This bulk removal enabled the treatment of highly contaminated fines and water through a permeable gate. The increased sediment loading during excavation required both modifications to the funnel and a shift to a more permeable, granular system. Granulated activated charcoal was chosen for its ability to both act as a particle retention filter and adsorptive filter. The reduction in mass of PCB and volume of soils trapped by the funnel of the barrier indicate that soils are re-stabilizing. In 2007, nonwoven geotextiles were re-introduced back into the filtration system as fine filtering could be achieved without clogging. Monitoring sites downstream indicate that the barrier system is effective. This paper describes the field progress of PCB remediation at Resolution Island.

Replacement of fluid-filter elements without interruption of flow

NASA Technical Reports Server (NTRS)

Kotler, R. A.; Ward, J. B.

1969-01-01

Gatling-type filter assembly, preloaded with several filter elements enables filter replacement without breaking into the operative fluid system. When the filter element becomes contaminated, a unit inner subassembly is rotated 60 degrees to position a clean filter in the line.

Effectiveness of in-room air filtration and dilution ventilation for tuberculosis infection control.

PubMed

Miller-Leiden, S; Lobascio, C; Nazaroff, W W; Macher, J M

1996-09-01

Tuberculosis (TB) is a public health problem that may pose substantial risks to health care workers and others. TB infection occurs by inhalation of airborne bacteria emitted by persons with active disease. We experimentally evaluated the effectiveness of in-room air filtration systems, specifically portable air filters (PAFs) and ceiling-mounted air filters (CMAFs), in conjunction with dilution ventilation, for controlling TB exposure in high-risk settings. For each experiment, a test aerosol was continuously generated and released into a full-sized room. With the in-room air filter and room ventilation system operating, time-averaged airborne particle concentrations were measured at several points. The effectiveness of in-room air filtration plus ventilation was determined by comparing particle concentrations with and without device operation. The four PAFs and three CMAFs we evaluated reduced room-average particle concentrations, typically by 30% to 90%, relative to a baseline scenario with two air-changes per hour of ventilation (outside air) only. Increasing the rate of air flow recirculating through the filter and/or air flow from the ventilation did not always increase effectiveness. Concentrations were generally higher near the emission source than elsewhere in the room. Both the air flow configuration of the filter and its placement within the room were important, influencing room air flow patterns and the spatial distribution of concentrations. Air filters containing efficient, but non-high efficiency particulate air (HEPA) filter media were as effective as air filters containing HEPA filter media.

Effectiveness of In-Room Air Filtration and Dilution Ventilation for Tuberculosis Infection Control.

PubMed

Miller-Leiden, S; Lohascio, C; Nazaroff, W W; Macher, J M

1996-09-01

Tuberculosis (TB) is a public health problem that may pose substantial risks to health care workers and others. TB infection occurs by inhalation of airborne bacteria emitted by persons with active disease. We experimentally evaluated the effectiveness of in-room air filtration systems, specifically portable air filters (PAFs) and ceiling-mounted air filters (CMAFs), in conjunction with dilution ventilation, for controlling TB exposure in high-risk settings. For each experiment, a test aerosol was continuously generated and released into a full-sized room. With the in-room air filter and room ventilation system operating, time-averaged airborne particle concentrations were measured at several points. The effectiveness of in-room air filtration plus ventilation was determined by comparing particle concentrations with and without device operation. The four PAFs and three CMAFs we evaluated reduced room-average particle concentrations, typically by 30% to 90%, relative to a baseline scenario with two air-changes per hour of ventilation (outside air) only. Increasing the rate of air flow recirculating through the filter and/or air flow from the ventilation did not always increase effectiveness. Concentrations were generally higher near the emission source than elsewhere in the room. Both the air flow configuration of the filter and its placement within the room were important, influencing room air flow patterns and the spatial distribution of concentrations. Air filters containing efficient, but non-high efficiency particulate air (HEPA) filter media were as effective as air filters containing HEPA filter media.

Frequency-Domain Characterization of Optic Flow and Vision-Based Ocellar Sensing for Rotational Motion

DTIC Science & Technology

2017-04-01

complementary fusion: Fourth-order Butterworth filter was used to high -pass ocelli and low-pass optic flow. The normalized cutoff frequency had to be kept...information introduced by luminance change. The high - frequency cutoff was added to reject the flickering noise for indoor usage. The filtered signals from the...function of the low- pass filter is to attenuate high - frequency noise. The final band-pass filter transfer function is in Eq. 2. (()

Continuous flow dielectrophoretic particle concentrator

DOEpatents

Cummings, Eric B [Livermore, CA

2007-04-17

A continuous-flow filter/concentrator for separating and/or concentrating particles in a fluid is disclosed. The filter is a three-port device an inlet port, an filter port and a concentrate port. The filter separates particles into two streams by the ratio of their dielectrophoretic mobility to their electrokinetic, advective, or diffusive mobility if the dominant transport mechanism is electrokinesis, advection, or diffusion, respectively.Also disclosed is a device for separating and/or concentrating particles by dielectrophoretic trapping of the particles.

Modeling sediment trapping in a vegetative filter accounting for converging overland flow

Treesearch

M. J. Helmers; D. E. Eisenhauer; T. G. Franti; M. G. Dosskey

2005-01-01

Vegetative filters (VF) are used to remove sediment and other pollutants from overland flow. When modeling the hydrology of VF, it is often assumed that overland flow is planar, but our research indicated that it can be two-dimensional with converging and diverging pathways. Our hypothesis is that flow convergence will negatively influence the sediment trapping...

Direct flow crystal growth system

DOEpatents

Montgomery, Kenneth E.; Milanovich, Fred P.

1992-01-01

A crystal is grown in a constantly filtered solution which is flowed directly into the growing face of a crystal. In a continuous flow system, solution at its saturation temperature is removed from a crystal growth tank, heated above its saturation temperature, filtered, cooled back to its saturation temperature, and returned to the tank.

Natural colloidal P and its contribution to plant P uptake.

PubMed

Montalvo, Daniela; Degryse, Fien; McLaughlin, Mike J

2015-03-17

Phosphorus (P) bioavailability depends on its concentration and speciation in solution. Andisols and Oxisols have very low soil solution concentration of free orthophosphate, as they contain high concentrations of strongly P-sorbing minerals (Al/Fe oxyhydroxides, allophanes). Free orthophosphate is the form of P taken up by plants, but it is not the only P species present in the soil solution. Natural colloidal P (P associated with Al, Fe, and organic matter of sizes ranging from 1 to 1000 nm) constitutes an important fraction of soil solution P in these soils; however, its availability has not been considered. We measured the uptake of P by wheat (Triticum aestivum) from radiolabeled nonfiltered (colloid-containing) and 3-kDa filtered (nearly colloid-free) soil-water extracts from Andisols and Oxisols. In the Andisol extracts, P uptake was up to 5-fold higher from the nonfiltered solutions than the corresponding 3-kDa filtered solutions. In the Oxisol extract, no difference in P uptake between both solutions was observed. Also the diffusional flux of P as measured with the DGT technique was larger in the nonfiltered than in the 3-kDa filtered solutions. Our results suggest that colloidal P from Andisols is not chemically inert and contributes to plant uptake of P.

Methodology to estimate the relative pressure field from noisy experimental velocity data

NASA Astrophysics Data System (ADS)

Bolin, C. D.; Raguin, L. G.

2008-11-01

The determination of intravascular pressure fields is important to the characterization of cardiovascular pathology. We present a two-stage method that solves the inverse problem of estimating the relative pressure field from noisy velocity fields measured by phase contrast magnetic resonance imaging (PC-MRI) on an irregular domain with limited spatial resolution, and includes a filter for the experimental noise. For the pressure calculation, the Poisson pressure equation is solved by embedding the irregular flow domain into a regular domain. To lessen the propagation of the noise inherent to the velocity measurements, three filters - a median filter and two physics-based filters - are evaluated using a 2-D Couette flow. The two physics-based filters outperform the median filter for the estimation of the relative pressure field for realistic signal-to-noise ratios (SNR = 5 to 30). The most accurate pressure field results from a filter that applies in a least-squares sense three constraints simultaneously: consistency between measured and filtered velocity fields, divergence-free and additional smoothness conditions. This filter leads to a 5-fold gain in accuracy for the estimated relative pressure field compared to without noise filtering, in conditions consistent with PC-MRI of the carotid artery: SNR = 5, 20 x 20 discretized flow domain (25 X 25 computational domain).

Soil Susceptibility to Macropore Flow Across a Desert-Oasis Ecotone of the Hexi Corridor, Northwest China

NASA Astrophysics Data System (ADS)

Zhang, Yongyong; Zhao, Wenzhi; He, Jianhua; Fu, Li

2018-02-01

Macropore flow not only provides a fast pathway for water and solute transport and increases the risks of water and nutrient loss but also enhances soil aeration and groundwater recharge. However, macropore flow characteristics in irrigated oasis soils subject to continuous crop cultivation are poorly understood. This study was to investigate the effect of continuous cultivation on soil properties and macropore flow and to quantify the changes in macropore flow characteristics in an old oasis field (>50 years of cultivation, OOF), young oasis field (20 years, YOF), and adjacent uncultivated sandy area (0 year, USL) in Northwest China. Triplicate soil samples were collected from each site to investigate soil properties. Dye tracer experiments with also three replicates were conducted at each site. The degree of macropore flow (i.e., parameters of macropore flow) was highest at the OOF, intermediate at the YOF, and minimal at the USL. The macropore flow fraction (i.e., fraction of total infiltration flows through macropore flow pathways) at the OOF was 3.4 times greater than at the USL. The heterogeneous infiltration pattern at the OOF was dominated by macropore flow, while funnel flow was predominant at the USL. Long-term irrigation with silt-laden river water has increased silt + clay contents of the oasis soils. Irrigation and high-input crop cultivation also increased organic matter. These changes in soil properties contributed to the interaggregate voids formation. The conversion of native desert soils to irrigated croplands increases the degree of macropore flow, which might enhance groundwater recharge in the desert-oasis ecotone.

Examining responses of ecosystem carbon exchange to environmental changes using particle filtering mathod

NASA Astrophysics Data System (ADS)

Yokozawa, M.

2017-12-01

Attention has been paid to the agricultural field that could regulate ecosystem carbon exchange by water management and residual treatments. However, there have been less known about the dynamic responses of the ecosystem to environmental changes. In this study, focussing on paddy field, where CO2 emissions due to microbial decomposition of organic matter are suppressed and alternatively CH4 emitted under flooding condition during rice growth season and subsequently CO2 emission following the fallow season after harvest, the responses of ecosystem carbon exchange were examined. We conducted model data fusion analysis for examining the response of cropland-atmosphere carbon exchange to environmental variation. The used model consists of two sub models, paddy rice growth sub-model and soil decomposition sub-model. The crop growth sub-model mimics the rice plant growth processes including formation of reproductive organs as well as leaf expansion. The soil decomposition sub-model simulates the decomposition process of soil organic carbon. Assimilating the data on the time changes in CO2 flux measured by eddy covariance method, rice plant biomass, LAI and the final yield with the model, the parameters were calibrated using a stochastic optimization algorithm with a particle filter method. The particle filter method, which is one of the Monte Carlo filters, enable us to evaluating time changes in parameters based on the observed data until the time and to make prediction of the system. Iterative filtering and prediction with changing parameters and/or boundary condition enable us to obtain time changes in parameters governing the crop production as well as carbon exchange. In this study, we focused on the parameters related to crop production as well as soil carbon storage. As the results, the calibrated model with estimated parameters could accurately predict the NEE flux in the subsequent years. The temperature sensitivity, denoted by Q10s in the decomposition rate of soil organic carbon (SOC) were obtained as 1.4 for no cultivation period and 2.9 for cultivation period (submerged soil condition in flooding season). It suggests that the response of ecosystem carbon exchange differs due to SOC decomposition process which is sensitive to environmental variation during paddy rice cultivation period.

A Wiener-Wavelet-Based filter for de-noising satellite soil moisture retrievals

NASA Astrophysics Data System (ADS)

Massari, Christian; Brocca, Luca; Ciabatta, Luca; Moramarco, Tommaso; Su, Chun-Hsu; Ryu, Dongryeol; Wagner, Wolfgang

2014-05-01

The reduction of noise in microwave satellite soil moisture (SM) retrievals is of paramount importance for practical applications especially for those associated with the study of climate changes, droughts, floods and other related hydrological processes. So far, Fourier based methods have been used for de-noising satellite SM retrievals by filtering either the observed emissivity time series (Du, 2012) or the retrieved SM observations (Su et al. 2013). This contribution introduces an alternative approach based on a Wiener-Wavelet-Based filtering (WWB) technique, which uses the Entropy-Based Wavelet de-noising method developed by Sang et al. (2009) to design both a causal and a non-causal version of the filter. WWB is used as a post-retrieval processing tool to enhance the quality of observations derived from the i) Advanced Microwave Scanning Radiometer for the Earth observing system (AMSR-E), ii) the Advanced SCATterometer (ASCAT), and iii) the Soil Moisture and Ocean Salinity (SMOS) satellite. The method is tested on three pilot sites located in Spain (Remedhus Network), in Greece (Hydrological Observatory of Athens) and in Australia (Oznet network), respectively. Different quantitative criteria are used to judge the goodness of the de-noising technique. Results show that WWB i) is able to improve both the correlation and the root mean squared differences between satellite retrievals and in situ soil moisture observations, and ii) effectively separates random noise from deterministic components of the retrieved signals. Moreover, the use of WWB de-noised data in place of raw observations within a hydrological application confirms the usefulness of the proposed filtering technique. Du, J. (2012), A method to improve satellite soil moisture retrievals based on Fourier analysis, Geophys. Res. Lett., 39, L15404, doi:10.1029/ 2012GL052435 Su,C.-H.,D.Ryu, A. W. Western, and W. Wagner (2013), De-noising of passive and active microwave satellite soil moisture time series, Geophys. Res. Lett., 40,3624-3630, doi:10.1002/grl.50695. Sang Y.-F., D. Wang, J.-C. Wu, Q.-P. Zhu, and L. Wang (2009), Entropy-Based Wavelet De-noising Method for Time Series Analysis, Entropy, 11, pp. 1123-1148, doi:10.3390/e11041123.

Rotational response of suspended particles to turbulent flow: laboratory and numerical synthesis

NASA Astrophysics Data System (ADS)

Variano, Evan; Zhao, Lihao; Byron, Margaret; Bellani, Gabriele; Tao, Yiheng; Andersson, Helge

2014-11-01

Using laboratory and DNS measurements, we consider how aspherical and inertial particles suspended in a turbulent flow act to ``filter'' the fluid-phase vorticity. We use three approaches to predict the magnitude and structure of this filter. The first approach is based on Buckingham's Pi theorem, which shows a clear result for the relationship between filter strength and particle aspect ratio. Results are less clear for the dependence of filter strength on Stokes number; we briefly discuss some issues in the proper definition of Stokes number for use in this context. The second approach to predicting filter strength is based on a consideration of vorticity and enstrophy spectra in the fluid phase. This method has a useful feature: it can be used to predict the filter a priori, without need for measurements as input. We compare the results of this approach to measurements as a method of validation. The third and final approach to predicting filter strength is from the consideration of torques experienced by particles, and how the ``angular slip'' or ``spin slip'' evolves in an unsteady flow. We show results from our DNS that indicate different flow conditions in which the spin slip is more or less important in setting the particle rotation dynamics. Collaboration made possible by the Peder Sather Center.

Vegetative filter strips efficiency controlling soil loss and trapping herbicides in two olive orchards at the short-term

NASA Astrophysics Data System (ADS)

de Luna, Elena; Guzmán, Gema; Gómez, José A.

2014-05-01

The optimization of water use in a semi-arid climate is based on an optimal use of rainwater adopting management practices that prevent and/or control runoff. This is a key point for increasing the economic and environmental sustainability of agriculture due to the minimization of diffuse pollution associated to runoff and to sediment and chemical transport. One strategy is the establishment of vegetative filters strips that prevent pesticides (Stehle et al. 2011), herbicides (Vianello et al. 2005), fertilizers (Withers et al. 2009) and runoff-sediment (Campo-Bescós et al. 2013) from entering streams or surface water reservoirs. To evaluate the short-term risks associated with the use of herbicides a trial was designed in two olive groves located in Benacazón (Sevilla) and Cabra (Córdoba) both with an average steepness of 11%. Two different management systems were evaluated, bare soil and bare soil with vegetative filter strips. Pre-emergence herbicides were applied and analysed at the beginning of the trial by chromatography GC-MS and after each rainfall event both in soil and sediment. Runoff and soil losses were measured, as well. The results obtained from this study show that soil management practices such as, the use of vegetative filter strips results in a reduction of soil losses and runoff. This it is translated in the improvement of soil quality and a reduction of water pollution caused by the use of herbicides. This information will improve the understanding of insufficiently known aspects and it will help to increase the knowledge for a better implementation of sustainable management practices at a farm scale and at larger temporal scale. References: Campo-Bescós, M. A., Muñoz-Carpena, R., & Kiker, G. (2013) Influencia del suelo en la eficiencia de la implantación de filtros verdes en un distrito de riego por superficie en medio árido. En Estudios de la Zona no Saturada del Suelo, Vol. XI: 183-187. Stehle, S., Elsaesser, D., Gregoire, C., Imfeld, G., Niehaus, E., Passeport, E., Payraudeau, S., Schäfera, R., Tournebize, J., & Schulz, R. (2011). Pesticide risk mitigation by vegetated treatment systems: a meta-analysis. Journal of Environmental Quality, 40: 1068-1080. Vianello, M., Vischetti, C., Scarponi, L., & Zanin, G. (2005). Herbicide losses in runoff events from a field with a low slope: role of a vegetative filter strip. Chemosphere, 61: 717-725. Withers, P. J. A., Hartikainen, H., Barberis, E., Flynn, N. J., & Warren, G. P. (2009). The effect of soil phosphorus on particulate phosphorus in land runoff. European Journal of Soil Science 60: 994-1004.

Potential bioactivity and association of 17β-estradiol with the dissolved and colloidal fractions of manure and soil.

PubMed

Chambers, Katrin B; Casey, Francis X M; Hakk, Heldur; DeSutter, Thomas M; Shappell, Nancy W

2014-10-01

The dissolved (DF) and colloidal fractions (CF) of soil and manure play an important role in the environmental fate and transport of steroidal estrogens. The first objective of this study was to quantify the association of 17β-estradiol (E2) with the DF and CF isolated from (i) liquid swine manure (LSM), (ii) a soil:water mixture (soil), and (iii) a LSM:soil:water mixture (Soil+LSM). The appropriate CF and DF size fractions of the Soil, Soil+LSM, and LSM media were obtained by first filtering through a 0.45 μm filter, which provided the combined DF and CF (DF/CF). The DF/CF from the three media was spiked with carbon-14 ([(14)C]) radiolabeled E2 ([(14)C]-E2), and then ultrafiltered to isolate the CF (<0.45 μm and >1 kDa) from the DF (<1 kDa). The average recoveries of the [(14)C] associated with the DF were 67%-72%, 67%-79%, and 76%-78% for the Soil, Soil+LSM and LSM, respectively. For the CF that was retained on the 1 kDa filter, organic carbon and [(14)C]-E2 were dislodged with subsequent water rinses the Soil+LSM and LSM, but not the Soil. The second objective was to evaluate whether the E2 associated with the various fractions of the different media could still bind the estrogen receptor using an E2 receptor (17β-ER) competitor assay, which allowed E2 equivalent concentrations to be determined. The estrogen receptor assay results indicated that E2 present in the DF of the Soil and Soil+LSM solutions could still bind the estrogen receptor. Results from this study indicated that E2 preferentially associated with the DF of soil and manure, which may enhance its dissolved advective transport in surface and subsurface water. Furthermore, this study indicated that E2 associated with DF solutions in the environment could potentially induce endocrine responses through its interactions with estrogen receptor. Copyright © 2014 Elsevier B.V. All rights reserved.

Improving long-term global precipitation dataset using multi-sensor surface soil moisture retrievals and the soil moisture analysis rainfall tool (SMART)

USDA-ARS?s Scientific Manuscript database

Using multiple historical satellite surface soil moisture products, the Kalman Filtering-based Soil Moisture Analysis Rainfall Tool (SMART) is applied to improve the accuracy of a multi-decadal global daily rainfall product that has been bias-corrected to match the monthly totals of available rain g...

Application of velocity filtering to optical-flow passive ranging

NASA Technical Reports Server (NTRS)

Barniv, Yair

1992-01-01

The performance of the velocity filtering method as applied to optical-flow passive ranging under real-world conditions is evaluated. The theory of the 3-D Fourier transform as applied to constant-speed moving points is reviewed, and the space-domain shift-and-add algorithm is derived from the general 3-D matched filtering formulation. The constant-speed algorithm is then modified to fit the actual speed encountered in the optical flow application, and the passband of that filter is found in terms of depth (sensor/object distance) so as to cover any given range of depths. Two algorithmic solutions for the problems associated with pixel interpolation and object expansion are developed, and experimental results are presented.

Optimizing Wastewater Reuse in Agricultural Fields via Merging of Embedded Network Sensor Data and Flow and Transport Models Using Data Assimilation

NASA Astrophysics Data System (ADS)

Wu, C.; Margulis, S. A.

2007-12-01

Wastewater re-use via crop irrigation has the potential to be an effective means of wastewater disposal. However, nitrate in wastewater may contaminate groundwater if it does not decay before reaching the groundwater table. In order to dispose of wastewater while preventing long-term groundwater pollution, irrigation rates need to be optimized based on the current and predicted states of the soil, such as soil moisture content and/or nitrate concentration. A real-time soil states estimation system using the Ensemble Kalman Filter (EnKF) has been developed for application to a test bed for wastewater re-use in Palmdale, CA. This test bed, covered with alfalfa, is a 30-acre irrigation plot with a 200-meter long rotating pivot arm that irrigates the area with reclaimed wastewater. A sensor network is deployed in the soil near the surface. The data assimilation system has shown the ability to characterize soil states and fluxes from sparse measurements. The real-time estimation system will then be used to explore the potential feedback for optimizing the sprinkler operation (i.e. maximizing the magnitude of wastewater release while minimizing the ultimate groundwater pollution). In optimization models, soil states and fluxes can be regarded as functions of irrigation rate. Through optimization, the irrigation rate in a finite horizon can be maximized while still satisfying all criteria in soil states and fluxes to ensure the safety of groundwater. Since the data assimilation system provides reliable estimation of soil states and fluxes, it is expected to define the optimal irrigation rate with higher confidence compared to using models or sensors only.

Percolation properties of 3-D multiscale pore networks: how connectivity controls soil filtration processes

NASA Astrophysics Data System (ADS)

Perrier, E. M. A.; Bird, N. R. A.; Rieutord, T. B.

2010-04-01

Quantifying the connectivity of pore networks is a key issue not only for modelling fluid flow and solute transport in porous media but also for assessing the ability of soil ecosystems to filter bacteria, viruses and any type of living microorganisms as well inert particles which pose a contamination risk. Straining is the main mechanical component of filtration processes: it is due to size effects, when a given soil retains a conveyed entity larger than the pores through which it is attempting to pass. We postulate that the range of sizes of entities which can be trapped inside soils has to be associated with the large range of scales involved in natural soil structures and that information on the pore size distribution has to be complemented by information on a Critical Filtration Size (CFS) delimiting the transition between percolating and non percolating regimes in multiscale pore networks. We show that the mass fractal dimensions which are classically used in soil science to quantify scaling laws in observed pore size distributions can also be used to build 3-D multiscale models of pore networks exhibiting such a critical transition. We extend to the 3-D case a new theoretical approach recently developed to address the connectivity of 2-D fractal networks (Bird and Perrier, 2009). Theoretical arguments based on renormalisation functions provide insight into multi-scale connectivity and a first estimation of CFS. Numerical experiments on 3-D prefractal media confirm the qualitative theory. These results open the way towards a new methodology to estimate soil filtration efficiency from the construction of soil structural models to be calibrated on available multiscale data.

Percolation properties of 3-D multiscale pore networks: how connectivity controls soil filtration processes

NASA Astrophysics Data System (ADS)

Perrier, E. M. A.; Bird, N. R. A.; Rieutord, T. B.

2010-10-01

Quantifying the connectivity of pore networks is a key issue not only for modelling fluid flow and solute transport in porous media but also for assessing the ability of soil ecosystems to filter bacteria, viruses and any type of living microorganisms as well inert particles which pose a contamination risk. Straining is the main mechanical component of filtration processes: it is due to size effects, when a given soil retains a conveyed entity larger than the pores through which it is attempting to pass. We postulate that the range of sizes of entities which can be trapped inside soils has to be associated with the large range of scales involved in natural soil structures and that information on the pore size distribution has to be complemented by information on a critical filtration size (CFS) delimiting the transition between percolating and non percolating regimes in multiscale pore networks. We show that the mass fractal dimensions which are classically used in soil science to quantify scaling laws in observed pore size distributions can also be used to build 3-D multiscale models of pore networks exhibiting such a critical transition. We extend to the 3-D case a new theoretical approach recently developed to address the connectivity of 2-D fractal networks (Bird and Perrier, 2009). Theoretical arguments based on renormalisation functions provide insight into multi-scale connectivity and a first estimation of CFS. Numerical experiments on 3-D prefractal media confirm the qualitative theory. These results open the way towards a new methodology to estimate soil filtration efficiency from the construction of soil structural models to be calibrated on available multiscale data.

Numerical studies on the performance of an aerosol respirator with faceseal leakage

NASA Astrophysics Data System (ADS)

Zaripov, S. K.; Mukhametzanov, I. T.; Grinshpun, S. A.

2016-11-01

We studied the efficiency of a facepiece filtering respirator (FFR) in presence of a measurable faceseal leakage using the previously developed model of a spherical sampler with porous layer. In our earlier study, the model was validated for a specific filter permeability value. In this follow-up study, we investigated the effect of permeability on the overall respirator performance accounting for the faceseal leakage. The Total Inward Leakage (TIL) was calculated as a function of the leakage-to-filter surface ratio and the particle diameter. A good correlation was found between the theoretical and experimental TIL values. The TIL value was shown to increase and the effect of particle size on TIL to decrease as the leakage-to- filter surface ratio grows. The model confirmed that within the most penetrating particle size range (∼50 nm) and at relatively low leakage-to-filter surface ratios, an FFR performs better (TIL is lower) when the filter has a lower permeability which should be anticipated as long as the flow through the filter represents the dominant particle penetration pathway. An increase in leak size causes the TIL to rise; furthermore, under certain leakage-to-filter surface ratios, TIL for ultrafine particles becomes essentially independent on the filter properties due to a greater contribution of the aerosol flow through the faceseal leakage. In contrast to the ultrafine fraction, the larger particles (e.g., 800 nm) entering a typical high- or medium-quality respirator filter are almost fully collected by the filter medium regardless of its permeability; at the same time, the fraction penetrated through the leakage appears to be permeability- dependent: higher permeability generally results in a lower pressure drop through the filter which increases the air flow through the filter at the expense of the leakage flow. The latter reduces the leakage effect thus improving the overall respiratory protection level. The findings of this study provide valuable information for developing new respirators with a predictable actual workplace protection factor.

Water flow pathway and the organic carbon discharge during rain storm events in a coniferous forested head watershed, Tokyo, central Japan

NASA Astrophysics Data System (ADS)

Moriizumi, Mihoko; Terajima, Tomomi

2010-05-01

The current intense discussion of the green house effect, that has been one of the main focuses on the carbon cycle in environmental systems of the earth, seems to be weakened the importance related to the effect of carbonic materials on substance movement in the aquatic environments; though it has just begun to be referred recently. Because dissolved organic carbon (DOC) in stream flows believes to play a main role of the carbon cycle in the fresh water environment, seasonal changes in DOC discharge were investigated in catchments with various scale and land use, especially in forested catchments which are one of the important sources of DOC. In order to understand the fundamental characteristics of the discharge of dissolved organic materials, stream flows, DOC, and fulvic acid like materials (FA) included in stream flows were measured in a coniferous forested head watershed. The watershed is located at the southeast edge of the Kanto mountain and is 40 km west of Tokyo with the elevation from 720 to 820 m and mean slope gradient of 38 degrees. Geology of the watershed is underlain by the sequence of mud and sand stones in Jurassic and the soil in the watershed is Cambisol (Inceptisols). The watershed composes of a dense cypress and cedar forest of 45 years old with poor understory vegetation. Observations were carried out for 6 rain storms of which the total precipitations ranged between 16.2 and 117.4 mm. The magnitude of the storms was classified into small, middle, and big events on the basis of the total precipitation of around 20, 40, and more than 70 mm. Stream flows were collected during the storm events by 1 hour interval and were passed through the 0.45 μm filters, and then the DOC concentrations in the flows were measured with a total organic carbon analyzer. The relative concentrations of fulvic acid (FA) in the flows were monitored with three dimensional excitations emission matrix fluorescence spectroscopy, because fulvic acid shows distinctive fluorescence peaks at around the excitation wave length of 340 nm and emission wave length of 440 nm. The timing of the peaks in DOC and FA occurred simultaneously or within 30 minutes prior to those in the stream flows. The relationship between DOC and stream flow showed linear correlations with various gradients in each event. However, the relationship between FA and stream flow showed the linear correlations only for the small and middle events and clockwise hysteresis relations occurred in the big storm events. The relationship between DOC and FA showed the linear correlations both for the extracted water of the shallow soil and for stream base flow composed mostly of groundwater discharge. However, the relationship in the storm flow closely distributed at that in the extracted water of the shallow soil. This thing reveals that DOC and FA were mainly flashed out from the shallow soil during the rain storm events. The quick rising and recession of the fulvic acid was likely provided by quick rain water discharge through the surface or near surface of the slope. However, the overland flow were rare in the watershed during the rain storms. This indicates that the rapid shallow subsurface flow, passed mainly through preferential flow pathways at the slope surface within the loose litter and root-permeated zone, was the main cause of the difference in discharge regimes between DOC and FA. The shallow subsurface flow may have flushed the FA in the near-surface of the soil, and then the relatively predominant discharge of DOC must have been caused during the big rain storm event.

SEISMIC PREDICTION USING UNATTACHED RADON DECAY PRODUCTS.

PubMed

Harley, Naomi H; Chittaporn, Passaporn; Fisenne, Isabel M

2017-11-01

Long-term measurements of the 222Rn concentration, 222Rn decay product activity, particle size distribution, and unattached, and attached 222Rn decay products, were made at two locations using the 22 y radon decay product 210Pb as their tracer. The particle size sampler collects both short lived 222Rn decay products that ultimately decay to 210Pb on the filters, and also airborne 210Pb. The measurements were made outdoors, at a suburban home and at Fernald, OH, a former uranium processing facility, on top of one of the two 226Ra storage silos containing 150 TBq 226Ra. The size distributions showed the unattached fractions, i.e. particle diameter 2-4 nm, to be 1.5% at the home and 14% at the silos. The unattached fraction of 218Po can be shown to be an immediate measure of the 222Rn concentration. The data indicates detection of the pressure driven 222Rn flow at the silo and with the enhanced measurement capability of a filtered air source versus the usual 222Rn gas measurement. It is proposed that real time measurements of unattached 218Po may be used to identify rapidly changing 222Rn concentrations associated with pressure driven soil air flow associated with seismic activity. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Pilot plant experiences using physical and biological treatment steps for the remediation of groundwater from a former MGP site.

PubMed

Wirthensohn, T; Schoeberl, P; Ghosh, U; Fuchs, W

2009-04-15

The production of manufactured gas at a site in Vienna, Austria led to the contamination of soil and groundwater with various pollutants including PAHs, hydrocarbons, phenols, BTEX, and cyanide. The site needs to be remediated to alleviate potential impacts to the environment. The chosen remediation concept includes the excavation of the core contaminated site and the setup of a hydraulic barrier to protect the surrounding aquifer. The extracted groundwater will be treated on-site. To design the foreseen pump-and-treat system, a pilot-scale plant was built and operated for 6 months. The scope of the present study was to test the effectiveness of different process steps, which included an aerated sedimentation basin, a submerged fixed film reactor (SFFR), a multi-media filter, and an activated carbon filter. The hydraulic retention time (HRT) was 7.0 h during normal flow conditions and 3.5h during high flow conditions. The treatment system was effective in reducing the various organic and inorganic pollutants in the pumped groundwater. However, it was also demonstrated that appropriate pre-treatment was essential to overcome problems with clogging due to precipitation of tar and sulfur compounds. The reduction of the typical contaminants, PAHs and BTEX, was more than 99.8%. All water quality parameters after treatment were below the Austrian legal requirements for discharge into public water bodies.

Change in filter strip performance over ten years

Treesearch

M.G. Dosskey; K.D. Hoagland; J.R. Brandle

2007-01-01

Effectiveness of filter strips may change over a period of years because key soil and vegetation conditions change after conversion of cultivated farmland to permanent vegetation. the main objectives of this study were to : 1) determine if effectiveness of a filter strip changes over years since establishment, and 2) determine if temporal change depends on vegetation...

A Passive EMI Filter with Access to the Ungrounded Motor Neutral Line-Its Effect on Eliminating Leakage Current from the Inverter Heat Sink-

NASA Astrophysics Data System (ADS)

Doumoto, Takafumi; Akagi, Hirofumi

This paper deals with a leakage current flowing out of the heat sink of a voltage-source PWM inverter. The heat-sink leakage current is caused by a steep change in the common-mode voltage produced by the inverter. It flows through parasitic capacitors between the heat sink and power semiconductor devices when no EMI filter is connected. Experimental results reveal that the heat-sink leakage current flows not into the supply side, but into the motor side. These understandings succeed in describing an equivalent common-mode circuit taking the parasitic capacitors into account. The authors have proposed a passive EMI filter that is unique in access to the ungrounded motor neutral line. It is discussed from this equivalent circuit that the passive EMI filter is effective in preventing the leakage current from flowing. Moreover, installation of another small-sized common-mode inductor at the ac side of the diode rectifier prevents the leakage current from flowing into the supply side. Experimental results obtained from a 200-V, 3.7-kW laboratory system confirm the effectiveness and viability of the EMI filter.

A baker's dozen of new particle flows for nonlinear filters, Bayesian decisions and transport

NASA Astrophysics Data System (ADS)

Daum, Fred; Huang, Jim

2015-05-01

We describe a baker's dozen of new particle flows to compute Bayes' rule for nonlinear filters, Bayesian decisions and learning as well as transport. Several of these new flows were inspired by transport theory, but others were inspired by physics or statistics or Markov chain Monte Carlo methods.

Ultrasonic filtration of industrial chemical solutions

NASA Technical Reports Server (NTRS)

Cosma, T.

1974-01-01

The practical results obtained as a result of filtering industrial chemical solutions under continuous flow conditions with the aid of an ultrasonic filter are presented. The main part of the assembly consists of an ultrasonic generator with an output power of about 400 W and the filtration assembly, in which there is a magnetostrictive amplifier constructed for 20.5 kHz. In addition to ensuring a continuous flow of filtered solution, ultrasonic filters can be replaced or cleaned at intervals of time that are 8-10 times greater than in the case of mechanical filters. They yield considerably better results as far as the size of the filtered particles is concerned. The parameters on which filtration quality depends are also presented.

Time-Domain Filtering for Spatial Large-Eddy Simulation

NASA Technical Reports Server (NTRS)

Pruett, C. David

1997-01-01

An approach to large-eddy simulation (LES) is developed whose subgrid-scale model incorporates filtering in the time domain, in contrast to conventional approaches, which exploit spatial filtering. The method is demonstrated in the simulation of a heated, compressible, axisymmetric jet, and results are compared with those obtained from fully resolved direct numerical simulation. The present approach was, in fact, motivated by the jet-flow problem and the desire to manipulate the flow by localized (point) sources for the purposes of noise suppression. Time-domain filtering appears to be more consistent with the modeling of point sources; moreover, time-domain filtering may resolve some fundamental inconsistencies associated with conventional space-filtered LES approaches.

Spatial characterization of riparian buffer effects on sediment loads from watershed systems.

PubMed

Momm, Henrique G; Bingner, Ronald L; Yuan, Yongping; Locke, Martin A; Wells, Robert R

2014-09-01

Understanding all watershed systems and their interactions is a complex, but critical, undertaking when developing practices designed to reduce topsoil loss and chemical/nutrient transport from agricultural fields. The presence of riparian buffer vegetation in agricultural landscapes can modify the characteristics of overland flow, promoting sediment deposition and nutrient filtering. Watershed simulation tools, such as the USDA-Annualized Agricultural Non-Point Source (AnnAGNPS) pollution model, typically require detailed information for each riparian buffer zone throughout the watershed describing the location, width, vegetation type, topography, and possible presence of concentrated flow paths through the riparian buffer zone. Research was conducted to develop GIS-based technology designed to spatially characterize riparian buffers and to estimate buffer efficiency in reducing sediment loads in a semiautomated fashion at watershed scale. The methodology combines modeling technology at different scales, at individual concentrated flow paths passing through the riparian zone, and at watershed scales. At the concentrated flow path scale, vegetative filter strip models are applied to estimate the sediment-trapping efficiency for each individual flow path, which are aggregated based on the watershed subdivision and used in the determination of the overall impact of the riparian vegetation at the watershed scale. This GIS-based technology is combined with AnnAGNPS to demonstrate the effect of riparian vegetation on sediment loadings from sheet and rill and ephemeral gully sources. The effects of variability in basic input parameters used to characterize riparian buffers, onto generated outputs at field scale (sediment trapping efficiency) and at watershed scale (sediment loadings from different sources) were evaluated and quantified. The AnnAGNPS riparian buffer component represents an important step in understanding and accounting for the effect of riparian vegetation, existing and/or managed, in reducing sediment loads at the watershed scale. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

TOMOGRAPHY OF PLASMA FLOWS IN THE UPPER SOLAR CONVECTION ZONE USING TIME-DISTANCE INVERSION COMBINING RIDGE AND PHASE-SPEED FILTERING

DOE Office of Scientific and Technical Information (OSTI.GOV)

Svanda, Michal, E-mail: michal@astronomie.cz; Astronomical Institute, Charles University in Prague, Faculty of Mathematics and Physics, V Holesovickach 2, CZ-18000 Prague 8

2013-09-20

The consistency of time-distance inversions for horizontal components of the plasma flow on supergranular scales in the upper solar convection zone is checked by comparing the results derived using two k-{omega} filtering procedures-ridge filtering and phase-speed filtering-commonly used in time-distance helioseismology. I show that both approaches result in similar flow estimates when finite-frequency sensitivity kernels are used. I further demonstrate that the performance of the inversion improves (in terms of a simultaneously better averaging kernel and a lower noise level) when the two approaches are combined together in one inversion. Using the combined inversion, I invert for horizontal flows inmore » the upper 10 Mm of the solar convection zone. The flows connected with supergranulation seem to be coherent only for the top {approx}5 Mm; deeper down there is a hint of change of the convection scales toward structures larger than supergranules.« less

Infiltration Processes and Flow Velocities Across the Landscape: When and Where is Macropore Flow Relevant?

NASA Astrophysics Data System (ADS)

Demand, D.; Blume, T.; Weiler, M.

2017-12-01

Preferential flow in macropores significantly affects the distributions of water and solutes in soil and many studies showed its relevance worldwide. Although some models include this process as a second pore domain, little is known about the spatial patterns and temporal dynamics. For example, while flow in the matrix is usually modeled and parameterized based on soil texture, an influence of texture on non-capillary flow for a given land-use class is poorly understood. To investigate the temporal and spatial dynamics on preferential flow we used a four-year soil moisture dataset from the mesoscale Attert catchment (288 km²) in Luxembourg. This dataset contains time series from 126 soil profiles in different textures and two land-use classes (forest, grassland). The soil moisture probes were installed in 10, 30 and 50 cm depth and measured in a 5-minute temporal resolution. Events were defined by a soil moisture increase higher than the instrument noise after a precipitation sum of more than 1 mm. Precipitation was measured next to the profiles so that each location could be associated to its unique precipitation characteristics. For every event and profile the soil moisture reaction was classified in sequential (ordered by depth) and non-sequential response. A non-sequential soil moisture reaction was used as an indicator of preferential flow. For sequential flow, the velocity was determined by the first reaction between two vertically adjacent sensors. The sensor reaction and wetting front velocity was analyzed in the context of precipitation characteristics and initial soil water content. Grassland sites showed a lower proportion of non-sequential flow than forest sites. For forest, non-sequential response is dependent on texture, rainfall intensity and initial water content. This is less distinct for the grassland sites. Furthermore, sequential reactions show higher flow velocities at sites, which also have high percentage of non-sequential response. In contrast, grassland sites show a more homogenous wetting front independent of soil texture. Compared against common modelling approaches of soil water flow, measured velocities show clear evidence of preferential flow, especially for forest soils. The analysis also shows that vegetation can alter the soil properties above the textural properties alone.

Computational Simulations of Inferior Vena Cava (IVC) Filter Placement and Hemodynamics in Patient-Specific Geometries

NASA Astrophysics Data System (ADS)

Aycock, Kenneth; Sastry, Shankar; Kim, Jibum; Shontz, Suzanne; Campbell, Robert; Manning, Keefe; Lynch, Frank; Craven, Brent

2013-11-01

A computational methodology for simulating inferior vena cava (IVC) filter placement and IVC hemodynamics was developed and tested on two patient-specific IVC geometries: a left-sided IVC, and an IVC with a retroaortic left renal vein. Virtual IVC filter placement was performed with finite element analysis (FEA) using non-linear material models and contact modeling, yielding maximum vein displacements of approximately 10% of the IVC diameters. Blood flow was then simulated using computational fluid dynamics (CFD) with four cases for each patient IVC: 1) an IVC only, 2) an IVC with a placed filter, 3) an IVC with a placed filter and a model embolus, all at resting flow conditions, and 4) an IVC with a placed filter and a model embolus at exercise flow conditions. Significant hemodynamic differences were observed between the two patient IVCs, with the development of a right-sided jet (all cases) and a larger stagnation region (cases 3-4) in the left-sided IVC. These results support further investigation of the effects of IVC filter placement on a patient-specific basis.

Comparison of Flow Impairment during Carotid Artery Stenting Using Two Types of Eccentric Filter Embolic Protection Devices.

PubMed

Nii, Kouhei; Tsutsumi, Masanori; Maeda, Hitoshi; Aikawa, Hiroshi; Inoue, Ritsuro; Eto, Ayumu; Sakamoto, Kimiya; Mitsutake, Takafumi; Hanada, Hayatsura; Kazekawa, Kiyoshi

2016-12-15

We investigated the angiographic findings and the clinical outcomes after carotid artery stenting (CAS) using two different, eccentric filter embolic protection devices (EPDs). Between July 2010 and August 2015, 175 CAS procedures were performed using a self-expandable closed-cell stent and a simple eccentric filter EPD (FilterWire EZ in 86 and Spider FX in 89 procedures). The angiographic findings (i.e., flow impairment and vasospasm) at the level of EPDs, neurologic events, and post-operative imaging results were compared between the FilterWire EZ and the Spider FX groups. The CAS was angiographically successful in all 175 procedures. However, the angiographs were obtained immediately after CAS-detected flow impairment in the distal internal carotid artery (ICA) in 11 (6.3%) and ICA spasms at the level of the EPD in 40 cases (22.9%). The incidence of these complications was higher with FilterWire EZ than Spider FX (ICA flow impairment of 10.5% vs. 2.2%, P = 0.03; vasospasm 30.2% vs. 15.7%, P = 0.03). There were nine neurologic events (5.1%); five patients were presented with transient ischemic attacks, three had minor strokes, and one had a major stroke. New MRI lesions were seen in 25 (29.1%) FilterWire-group and in 36 (40.4%) Spider-group patients. The neurologic events and new MRI lesions were not associated with the type of EPD used. Although the ICA flow impairment may result in neurologic events, there was no significant association between the FilterWire EZ and the Spider FX CAS with respect to the incidence of neurologic events by the prompt treatment such as catheter aspiration.

Design of Airport Pavements for Expansive Soils.

DTIC Science & Technology

1981-01-01

8217. . C.Iqt N. - DOT 7 "//-;-31/2I...... , _Ai --i/ 6Z/ ,d, ,-,,’/Design of Airport Pavements for Expansive Soils. JanLapy 1981 6. Per.omingOvgn,, en Code...L/)- V) 3 00L C)- LO en id ’NUN 51J. filter paper (next to the top of the sample) was used as the measure of soil suction. The second filter paper...8217 SITE 4 2 2 3 4 SUCTION, pF FIGURE 4-18. VARIATION OF SUCTION DURING RECHARGE AT DFW. 69 lij ’I41d3U IJ 6id3a LhLO U.. to U.. C.-9 en C, 00 ’U- LA jto

Simulating root-induced rhizosphere deformation and its effect on water flow

NASA Astrophysics Data System (ADS)

Aravena, J. E.; Ruiz, S.; Mandava, A.; Regentova, E. E.; Ghezzehei, T.; Berli, M.; Tyler, S. W.

2011-12-01

Soil structure in the rhizosphere is influenced by root activities, such as mucilage production, microbial activity and root growth. Root growth alters soil structure by moving and deforming soil aggregates, affecting water and nutrient flow from the bulk soil to the root surface. In this study, we utilized synchrotron X-ray micro-tomography (XMT) and finite element analysis to quantify the effect of root-induced compaction on water flow through the rhizosphere to the root surface. In a first step, finite element meshes of structured soil around the root were created by processing rhizosphere XMT images. Then, soil deformation by root expansion was simulated using COMSOL Multiphysics° (Version 4.2) considering the soil an elasto-plastic porous material. Finally, fluid flow simulations were carried out on the deformed mesh to quantify the effect of root-induced compaction on water flow to the root surface. We found a 31% increase in water flow from the bulk soil to the root due to a 56% increase in root diameter. Simulations also show that the increase of root-soil contact area was the dominating factor with respect to the calculated increase in water flow. Increase of inter-aggregate contacts in size and number were observed within a couple of root diameters away from the root surface. But their influence on water flow was, in this case, rather limited compared to the immediate soil-root contact.

In Vitro Evaluation of a Rheolytic Thrombectomy System for Clot Removal from Five Different Temporary Vena Cava Filters

DOE Office of Scientific and Technical Information (OSTI.GOV)

Buecker, Arno; Neuerburg, Joerg; Schmitz-Rode, Thomas

1997-11-15

Purpose: To evaluate the feasibility of thrombus removal from temporary vena cava filters using a rheolytic thrombectomy device and to assess the embolization rate of this procedure. Methods: Five temporary vena cava filters together with porcine thrombi were placed in a vena cava flow model (semitranslucent silicone tube of 23 mm diameter, pulsatile flow at a mean flow rate of 4 L/min). A rheolytic thrombectomy system (Hydrolyser) was used with a 9 Fr guiding catheter to remove the clots. The effluent was passed through filters of different size and the amount of embolized particles as well as the remaining thrombusmore » were measured. Results: Thrombus removal rates ranged from 85% to 100%. Embolization rates between 47% and 60% were calculated for the different filters. Conclusion: The Hydrolyser is able to remove sufficiently high amounts of thrombus from temporary vena cava filters. However, the amount of embolized particles makes it impossible to utilize this method without special precautions against embolization.« less

Multi-decadal analysis of root-zone soil moisture applying the exponential filter across CONUS

NASA Astrophysics Data System (ADS)

Tobin, Kenneth J.; Torres, Roberto; Crow, Wade T.; Bennett, Marvin E.

2017-09-01

This study applied the exponential filter to produce an estimate of root-zone soil moisture (RZSM). Four types of microwave-based, surface satellite soil moisture were used. The core remotely sensed data for this study came from NASA's long-lasting AMSR-E mission. Additionally, three other products were obtained from the European Space Agency Climate Change Initiative (CCI). These datasets were blended based on all available satellite observations (CCI-active, CCI-passive, and CCI-combined). All of these products were 0.25° and taken daily. We applied the filter to produce a soil moisture index (SWI) that others have successfully used to estimate RZSM. The only unknown in this approach was the characteristic time of soil moisture variation (T). We examined five different eras (1997-2002; 2002-2005; 2005-2008; 2008-2011; 2011-2014) that represented periods with different satellite data sensors. SWI values were compared with in situ soil moisture data from the International Soil Moisture Network at a depth ranging from 20 to 25 cm. Selected networks included the US Department of Energy Atmospheric Radiation Measurement (ARM) program (25 cm), Soil Climate Analysis Network (SCAN; 20.32 cm), SNOwpack TELemetry (SNOTEL; 20.32 cm), and the US Climate Reference Network (USCRN; 20 cm). We selected in situ stations that had reasonable completeness. These datasets were used to filter out periods with freezing temperatures and rainfall using data from the Parameter elevation Regression on Independent Slopes Model (PRISM). Additionally, we only examined sites where surface and root-zone soil moisture had a reasonably high lagged r value (r > 0. 5). The unknown T value was constrained based on two approaches: optimization of root mean square error (RMSE) and calculation based on the normalized difference vegetation index (NDVI) value. Both approaches yielded comparable results; although, as to be expected, the optimization approach generally outperformed NDVI-based estimates. The best results were noted at stations that had an absolute bias within 10 %. SWI estimates were more impacted by the in situ network than the surface satellite product used to drive the exponential filter. The average Nash-Sutcliffe coefficients (NSs) for ARM ranged from -0. 1 to 0.3 and were similar to the results obtained from the USCRN network (0.2-0.3). NS values from the SCAN and SNOTEL networks were slightly higher (0.1-0.5). These results indicated that this approach had some skill in providing an estimate of RZSM. In terms of RMSE (in volumetric soil moisture), ARM values actually outperformed those from other networks (0.02-0.04). SCAN and USCRN RMSE average values ranged from 0.04 to 0.06 and SNOTEL average RMSE values were higher (0.05-0.07). These values were close to 0.04, which is the baseline value for accuracy designated for many satellite soil moisture missions.

Improving hydrologic predictions of a catchment model via assimilation of surface soil moisture

USDA-ARS?s Scientific Manuscript database

This paper examines the potential for improving Soil and Water Assessment Tool (SWAT) hydrologic predictions within the 341 km2 Cobb Creek Watershed in southwestern Oklahoma through the assimilation of surface soil moisture observations using an Ensemble Kalman filter (EnKF). In a series of synthet...

Implementation of surface soil moisture data assimilation with watershed scale distributed hydrological model

USDA-ARS?s Scientific Manuscript database

This paper aims to investigate how surface soil moisture data assimilation affects each hydrologic process and how spatially varying inputs affect the potential capability of surface soil moisture assimilation at the watershed scale. The Ensemble Kalman Filter (EnKF) is coupled with a watershed scal...

Data analysis using scale-space filtering and Bayesian probabilistic reasoning

NASA Technical Reports Server (NTRS)

Kulkarni, Deepak; Kutulakos, Kiriakos; Robinson, Peter

1991-01-01

This paper describes a program for analysis of output curves from Differential Thermal Analyzer (DTA). The program first extracts probabilistic qualitative features from a DTA curve of a soil sample, and then uses Bayesian probabilistic reasoning to infer the mineral in the soil. The qualifier module employs a simple and efficient extension of scale-space filtering suitable for handling DTA data. We have observed that points can vanish from contours in the scale-space image when filtering operations are not highly accurate. To handle the problem of vanishing points, perceptual organizations heuristics are used to group the points into lines. Next, these lines are grouped into contours by using additional heuristics. Probabilities are associated with these contours using domain-specific correlations. A Bayes tree classifier processes probabilistic features to infer the presence of different minerals in the soil. Experiments show that the algorithm that uses domain-specific correlation to infer qualitative features outperforms a domain-independent algorithm that does not.

Moment Analysis Characterizing Water Flow in Repellent Soils from On- and Sub-Surface Point Sources

NASA Astrophysics Data System (ADS)

Xiong, Yunwu; Furman, Alex; Wallach, Rony

2010-05-01

Water repellency has a significant impact on water flow patterns in the soil profile. Flow tends to become unstable in such soils, which affects the water availability to plants and subsurface hydrology. In this paper, water flow in repellent soils was experimentally studied using the light reflection method. The transient 2D moisture profiles were monitored by CCD camera for tested soils packed in a transparent flow chamber. Water infiltration experiments and subsequent redistribution from on-surface and subsurface point sources with different flow rates were conducted for two soils of different repellency degrees as well as for wettable soil. We used spatio-statistical analysis (moments) to characterize the flow patterns. The zeroth moment is related to the total volume of water inside the moisture plume, and the first and second moments are affinitive to the center of mass and spatial variances of the moisture plume, respectively. The experimental results demonstrate that both the general shape and size of the wetting plume and the moisture distribution within the plume for the repellent soils are significantly different from that for the wettable soil. The wetting plume of the repellent soils is smaller, narrower, and longer (finger-like) than that of the wettable soil compared with that for the wettable soil that tended to roundness. Compared to the wettable soil, where the soil water content decreases radially from the source, moisture content for the water-repellent soils is higher, relatively uniform horizontally and gradually increases with depth (saturation overshoot), indicating that flow tends to become unstable. Ellipses, defined around the mass center and whose semi-axes represented a particular number of spatial variances, were successfully used to simulate the spatial and temporal variation of the moisture distribution in the soil profiles. Cumulative probability functions were defined for the water enclosed in these ellipses. Practically identical cumulative probability functions (beta distribution) were obtained for all soils, all source types, and flow rates. Further, same distributions were obtained for the infiltration and redistribution processes. This attractive result demonstrates the competence and advantage of the moment analysis method.

Simulation and validation of concentrated subsurface lateral flow paths in an agricultural landscape

NASA Astrophysics Data System (ADS)

Zhu, Q.; Lin, H. S.

2009-08-01

The importance of soil water flow paths to the transport of nutrients and contaminants has long been recognized. However, effective means of detecting concentrated subsurface flow paths in a large landscape are still lacking. The flow direction and accumulation algorithm based on single-direction flow algorithm (D8) in GIS hydrologic modeling is a cost-effective way to simulate potential concentrated flow paths over a large area once relevant data are collected. This study tested the D8 algorithm for simulating concentrated lateral flow paths at three interfaces in soil profiles in a 19.5-ha agricultural landscape in central Pennsylvania, USA. These interfaces were (1) the interface between surface plowed layers of Ap1 and Ap2 horizons, (2) the interface with subsoil water-restricting clay layer where clay content increased to over 40%, and (3) the soil-bedrock interface. The simulated flow paths were validated through soil hydrologic monitoring, geophysical surveys, and observable soil morphological features. The results confirmed that concentrated subsurface lateral flow occurred at the interfaces with the clay layer and the underlying bedrock. At these two interfaces, the soils on the simulated flow paths were closer to saturation and showed more temporally unstable moisture dynamics than those off the simulated flow paths. Apparent electrical conductivity in the soil on the simulated flow paths was elevated and temporally unstable as compared to those outside the simulated paths. The soil cores collected from the simulated flow paths showed significantly higher Mn content at these interfaces than those away from the simulated paths. These results suggest that (1) the D8 algorithm is useful in simulating possible concentrated subsurface lateral flow paths if used with appropriate threshold value of contributing area and sufficiently detailed digital elevation model (DEM); (2) repeated electromagnetic surveys can reflect the temporal change of soil water storage and thus is a useful indicator of possible subsurface flow path over a large area; and (3) observable Mn distribution in soil profiles can be used as a simple indicator of water flow paths in soils and over the landscape; however, it does require sufficient soil sampling (by excavation or augering) to possibly infer landscape-scale subsurface flow paths. In areas where subsurface interface topography varies similarly with surface topography, surface DEM can be used to simulate potential subsurface lateral flow path reasonably so the cost associated with obtaining depth to subsurface water-restricting layer can be minimized.

Intermittent flux from a sand filter for household wastewater and integrated solute transfer to the vadose zone.

PubMed

Nasri, Behzad; Fouché, Olivier

2018-02-24

Depending on the actual number of soil-based on-site wastewater treatment system (OWTS) in an area, on-site sanitation may be a significant source of pollutants and a threat to groundwater. Even in the case of a system functioning correctly, here, a sand filter substituted for the in-situ soil, as the treated effluent may reach to the water table, it is necessary evaluating in situ how much the sand and underneath soil respectively contribute to pollutant removal. On the plot of a household in a small rural community, the functioning of a real scale OWTS was monitored for 1.5 years. This system, composed of a septic tank connected to a 5 × 5 m 2 and 0.7-m thick aerobic sand filter was equipped with soil hydrodynamic probes (water content and matrix potential) during construction. By using the instantaneous profile method of water content, the intermittent infiltrated flux was determined across the sand-pack according to position and time. Treated water infiltrates into underneath soil acting as post-treatment. Quality of interstitial liquid from the sand and the soil was analysed each month on a 12-h pumping sample obtained through porous plates. Results of water fluxes and concentrations provide an estimate of the annual flux to the vadose zone and groundwater of metals, nutrients and some organic micro-pollutants (parabens and triclosan) through the OWTS and subsoil.

Criterion 4: Conservation and maintenance of soil and water resources

Treesearch

Stephen R. Shifley; Francisco X. Aguilar; Nianfu Song; Susan I. Stewart; David J. Nowak; Dale D. Gormanson; W. Keith Moser; Sherri Wormstead; Eric J. Greenfield

2012-01-01

Soils are the fundamental resource enabling land to provide a wide array of benefits. Both humans and wildlife rely on soils for the production of life-sustaining nourishment and shelter. Soil is important to society because it supports plants that supply food, fibers, drugs, and other essentials and because it filters water and recycles wastes.The factors that affect...

Soil conditions drive changes in a key leaf functional trait through environmental filtering and facilitative interactions

NASA Astrophysics Data System (ADS)

Molina-Venegas, Rafael; Aparicio, Abelardo; Lavergne, Sébastien; Arroyo, Juan

2018-01-01

Non-random patterns in the functional structure of communities are often interpreted as evidence for different forces governing their assemblage. However, community assembly processes may act antagonistically, countering each other's signatures on the functional structure of communities, which may lead to spurious inferences on the underlying mechanisms. To illustrate this issue, we assessed the joint effects of environmental filtering and facilitative interactions on a key leaf functional trait (i.e. specific leaf area, SLA) in Mediterranean dwarf-shrub communities, using a two-scale sampling approach. Specifically, we analyzed differences in community-weighted mean SLA values (CWM-SLA) between communities (community-scale) and between guilds within communities (guild-scale, i.e. individuals sampled in understorey, overstorey and open-ground conditions) across contrasted soil environments and elevational gradients. We found that communities on harsh edaphic conditions (i.e. dolomite habitats) showed significantly lower CWM-SLA values than communities on more fertile habitats. In contrast, elevation was a poor predictor of differences in CWM-SLA between the communities. This suggests that environmental filtering may influence leaf trait variation along soil gradients irrespective of elevation. On the other hand, communities on dolomite habitats showed strong differences in CWM-SLA between understorey (higher CWM-SLA) and either open-ground and overstorey guilds (lower CWM-SLA), whereas communities on more fertile soils showed no differences between the guilds. The strong differences in CWM-SLA between understorey and non-understorey guilds in dolomite communities suggest that facilitative interactions may be particularly at stake under stressful edaphic conditions, thus partially mitigating the effect of environmental filtering (i.e. low SLA values) on communities growing in harsh soils.

Radiological/biological/aerosol removal system

DOEpatents

Haslam, Jeffery J

2015-03-17

An air filter replacement system for existing buildings, vehicles, arenas, and other enclosed airspaces includes a replacement air filter for replacing a standard air filter. The replacement air filter has dimensions and air flow specifications that allow it to replace the standard air filter. The replacement air filter includes a filter material that removes radiological or biological or aerosol particles.

Performance Evaluation of Axial Flow AG-1 FC and Prototype FM (High Strength) HEPA Filters - 13123

DOE Office of Scientific and Technical Information (OSTI.GOV)

Giffin, Paxton K.; Parsons, Michael S.; Wilson, John A.

High efficiency particulate air (HEPA) filters are routinely used in DOE nuclear containment activities. The Nuclear Air Cleaning Handbook (NACH) stipulates that air cleaning devices and equipment used in DOE nuclear applications must meet the American Society of Mechanical Engineers (ASME) Code on Nuclear Air and Gas Treatment (AG-1) standard. This testing activity evaluates two different axial flow HEPA filters, those from AG-1 Sections FC and FM. Section FM is under development and has not yet been added to AG-1 due to a lack of qualification data available for these filters. Section FC filters are axial flow units that utilizemore » a fibrous glass filtering medium. The section FM filters utilize a similar fibrous glass medium, but also have scrim backing. The scrim-backed filters have demonstrated the ability to endure pressure impulses capable of completely destroying FC filters. The testing activities presented herein will examine the total lifetime loading for both FC and FM filters under ambient conditions and at elevated conditions of temperature and relative humidity. Results will include loading curves, penetration curves, and testing condition parameters. These testing activities have been developed through collaborations with representatives from the National Nuclear Security Administration (NNSA), DOE Office of Environmental Management (DOE-EM), New Mexico State University, and Mississippi State University. (authors)« less

Soil Variable Permeability and Water Phase Change Dynamics in a Wastewater Spray Irrigation Agricultural System Located in a Seasonably Cold Climate

NASA Astrophysics Data System (ADS)

Darnault, C. J. G.; Daniel, T. J.; Billy, G.; Hopkins, I.; Guo, L.; Jin, Z.; Gall, H. E.; Lin, H.

2017-12-01

The permeability of the upper meter of soils in frozen conditions, commonly referred to as the active layer, can vary exponentially given the time of year. Variable moisture contents along with temperature, radiation, and slope angle of the soil surface can result in variable depths of frozen soils, which can cause the formation of low permeability ice lenses well into the spring thaw period. The wastewater irrigation site known as the "Living Filter" located in State College, PA has been in continuous operation since 1962. On average 5500 m3/day of wastewater is applied to the site annually, even in the winter months when average temperatures can dip as low as -7 °C during the month of January. The Living Filter is not permitted to discharge to surface water and is intended to recharge the Spring Creek basin that directly underlies the site, therefore runoff from the site is not permitted. We hypothesize that water infiltrates the upper meter of the subsurface during the winter in several different ways such as preferential pathways in the ice layer created by plant stems and weak patches of ice thawed by the warm wastewater. 2D conceptual models of the phase change between ice and water in the soil were created in order to predict soil permeability and its change in temperature. The 2D conceptual models can be correlated between observed soil moisture content and soil temperature data in order to validate the model given spray irrigation and weather patterns. By determining the permeability of the frozen soils, irrigation practices can be adjusted for the winter months so as to reduce the risk of any accidental wastewater runoff. The impact of this study will result in a better understanding of the multiphase dynamics of the active layer and their implication on soil hydrology at the Living Filter and other seasonally frozen sites.

Mechanisms of nutrient attenuation in a subsurface flow riparian wetland.

PubMed

Casey, R E; Taylor, M D; Klaine, S J

2001-01-01

Riparian wetlands are transition zones between terrestrial and aquatic environments that have the potential to serve as nutrient filters for surface and ground water due to their topographic location. We investigated a riparian wetland that had been receiving intermittent inputs of NO3- and PO4(3-) during storm runoff events to determine the mechanisms of nutrient attenuation in the wetland soils. Few studies have shown whether infrequent pulses of NO3- are sufficient to maintain substantial denitrifying communities. Denitrification rates were highest at the upstream side of the wetland where nutrient-rich runoff first enters the wetland (17-58 microg N2O-N kg soil(-1) h(-1)) and decreased further into the wetland. Carbon limitation for denitrification was minor in the wetland soils. Samples not amended with dextrose had 75% of the denitrification rate of samples with excess dextrose C. Phosphate sorption isotherms suggested that the wetland soils had a high capacity for P retention. The calculated soil PO4(3-) concentration that would yield an equilibrium aqueous P04(3-) concentration of 0.05 mg P L(-1) was found to be 100 times greater than the soil PO4(3-) concentration at the time of sampling. This indicated that the wetland could retain a large additional mass of PO4(3-) without increasing the dissolved P04(3-) concentrations above USEPA recommended levels for lentic waters. These results demonstrated that denitrification can be substantial in systems receiving pulsed NO3- inputs and that sorption could account for extensive PO4(3-) attenuation observed at this site.

Release of Rhizobium spp. from Tropical Soils and Recovery for Immunofluorescence Enumeration

PubMed Central

Kingsley, Mark T.; Bohlool, B. Ben

1981-01-01

Limitations associated with immunofluorescence enumeration of bacteria in soil derive largely from the efficiency with which cells can be separated from soil particles and collected on membrane filters for staining. Many tropical soils fix added bacteria tightly, resulting in low recoveries. Eight soils, representative of three of the major soil orders found in the tropics (oxisols, vertisols, and inceptisols), were tested for recovery of added Rhizobium strains. All except one Hawaiian andept (Typic Eutrandept) yielded recoveries ranging from <1 to 13%. Recovery from the andept was 100%. In soil-sand mixtures, addition of only a small amount of soil caused a dramatic decrease in recovery of added rhizobia. Increasing the soil content of the mixture from 0% (10 g of sand) to 50% (5 g of soil-5 g of sand) reduced recoveries from >90 to <1%. Varying the ionic strength and pH of the extracting solution did not cause marked increases in recovery. Protein solutions, ethylenediaminetetraacetate, and NaHCO3, on the other hand, improved release of bacteria. We report a modification to the usual membrane filter immunofluorescence procedure which yielded consistently high and reproducible recovery (coefficient of variation, 30%) of rhizobia from several tropical soils. In the modified procedure, partially hydrolyzed gelatin, diluted in ammonium phosphate, was used to suspend the soil. This caused dispersion of the soil and release of the bacteria from soil flocs. The efficiency of recovery of Rhizobium spp. from several tropical and two temperate soils remained high as the content of these soils in soil-sand mixtures was increased from 0 to 100%. The modified membrane filter immunofluorescence procedure was used to follow the growth of a strain of chickpea (Cicer arietinum) Rhizobium in a sterilized oxisol. The results showed a close agreement with viable counts at different stages during the growth cycle. Diluent for the hydrolyzed gelatin also had a marked effect on recovery. The efficiency of release of Rhizobium spp. from an oxisol was in the following order for the diluents used: 0.1 M (NH4)2HPO4 > 0.1 M Na2HPO4 = 0.1 M sodium-phosphate-buffered saline (pH 7.2) > 0.2 M NH4Cl > 0.2 KCl > NaCl = LiCl > water. Images PMID:16345824

Release of Rhizobium spp. from Tropical Soils and Recovery for Immunofluorescence Enumeration.

PubMed

Kingsley, M T; Bohlool, B B

1981-08-01

Limitations associated with immunofluorescence enumeration of bacteria in soil derive largely from the efficiency with which cells can be separated from soil particles and collected on membrane filters for staining. Many tropical soils fix added bacteria tightly, resulting in low recoveries. Eight soils, representative of three of the major soil orders found in the tropics (oxisols, vertisols, and inceptisols), were tested for recovery of added Rhizobium strains. All except one Hawaiian andept (Typic Eutrandept) yielded recoveries ranging from <1 to 13%. Recovery from the andept was 100%. In soil-sand mixtures, addition of only a small amount of soil caused a dramatic decrease in recovery of added rhizobia. Increasing the soil content of the mixture from 0% (10 g of sand) to 50% (5 g of soil-5 g of sand) reduced recoveries from >90 to <1%. Varying the ionic strength and pH of the extracting solution did not cause marked increases in recovery. Protein solutions, ethylenediaminetetraacetate, and NaHCO(3), on the other hand, improved release of bacteria. We report a modification to the usual membrane filter immunofluorescence procedure which yielded consistently high and reproducible recovery (coefficient of variation, 30%) of rhizobia from several tropical soils. In the modified procedure, partially hydrolyzed gelatin, diluted in ammonium phosphate, was used to suspend the soil. This caused dispersion of the soil and release of the bacteria from soil flocs. The efficiency of recovery of Rhizobium spp. from several tropical and two temperate soils remained high as the content of these soils in soil-sand mixtures was increased from 0 to 100%. The modified membrane filter immunofluorescence procedure was used to follow the growth of a strain of chickpea (Cicer arietinum) Rhizobium in a sterilized oxisol. The results showed a close agreement with viable counts at different stages during the growth cycle. Diluent for the hydrolyzed gelatin also had a marked effect on recovery. The efficiency of release of Rhizobium spp. from an oxisol was in the following order for the diluents used: 0.1 M (NH(4))(2)HPO(4) > 0.1 M Na(2)HPO(4) = 0.1 M sodium-phosphate-buffered saline (pH 7.2) > 0.2 M NH(4)Cl > 0.2 KCl > NaCl = LiCl > water.

Electrically heated particulate filter with zoned exhaust flow control

DOEpatents

Gonze, Eugene V [Pinckney, MI

2012-06-26

A system includes a particulate matter (PM) filter that includes X zones. An electrical heater includes Y heater segments that are associated with respective ones of the X zones. The electrical heater is arranged upstream from and proximate with the PM filter. A valve assembly includes Z sections that are associated with respective ones of the X zones. A control module adjusts flow through each of the Z sections during regeneration of the PM filter via control of the valve assembly. X, Y and Z are integers.

Root-soil air gap and resistance to water flow at the soil-root interface of Robinia pseudoacacia.

PubMed

Liu, X P; Zhang, W J; Wang, X Y; Cai, Y J; Chang, J G

2015-12-01

During periods of water deficit, growing roots may shrink, retaining only partial contact with the soil. In this study, known mathematical models were used to calculate the root-soil air gap and water flow resistance at the soil-root interface, respectively, of Robinia pseudoacacia L. under different water conditions. Using a digital camera, the root-soil air gap of R. pseudoacacia was investigated in a root growth chamber; this root-soil air gap and the model-inferred water flow resistance at the soil-root interface were compared with predictions based on a separate outdoor experiment. The results indicated progressively greater root shrinkage and loss of root-soil contact with decreasing soil water potential. The average widths of the root-soil air gap for R. pseudoacacia in open fields and in the root growth chamber were 0.24 and 0.39 mm, respectively. The resistance to water flow at the soil-root interface in both environments increased with decreasing soil water potential. Stepwise regression analysis demonstrated that soil water potential and soil temperature were the best predictors of variation in the root-soil air gap. A combination of soil water potential, soil temperature, root-air water potential difference and soil-root water potential difference best predicted the resistance to water flow at the soil-root interface. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Current Ground Test Options for Nuclear Thermal Propulsion (NTP)

NASA Technical Reports Server (NTRS)

Gerrish, Harold P., Jr.

2014-01-01

About 20 different NTP engines/ reactors were tested from 1959 to 1972 as part of the Rover and Nuclear Engine for Rocket Vehicle Application (NERVA) program. Most were tested in open air at test cell A or test cell C, at the Nevada Test Site (NTS). Even after serious engine breakdowns of the reactor (e.g., Phoebus 1A), the test cells were cleaned up for other engine tests. The engine test stand (ETS) was made for high altitude (approximately 1 psia) testing of an NTP engine with a flight configuration, but still had the exhaust released to open air. The Rover/NERVA program became aware of new environmental regulations which would prohibit the release of any significant quantity of radioactive particulates and noble gases into the open air. The nuclear furnace (NF-1) was the last reactor tested before the program was cancelled in 1973, but successfully demonstrated a scrubber concept on how to filter the NTP exhaust. The NF-1 was demonstrated in the summer of 1972. The NF-1 used a 44MW reactor and operated each run for approximately 90 minutes. The system cooled the hot hydrogen exhaust from the engine with a water spray before entering a particle filter. The exhaust then passed through a series of heat exchangers and water separators to help remove water from the exhaust and further reduce the exhaust temperatures. The exhaust was next prepared for the charcoal trap by passing through a dryer and effluent cooler to bring exhaust temperatures close to liquid nitrogen. At those low temperatures, most of the noble gases (e.g., Xe and Kr made from fission products) get captured in the charcoal trap. The filtered hydrogen is finally passed through a flare stack and released to the air. The concept was overall successful but did show a La plating on some surfaces and had multiple recommendations for improvement. The most recent detailed study on the NTP scrubber concept was performed by the ARES Corporation in 2006. The concept is based on a 50,000 lbf thrust engine (approximately 1 GW) with a maximum burn time of 1 hour. The concept utilized lessons learned from NF-1. The strategy breaks down the exhaust into parallel paths to allow flexibility with engine size and mass flow of exhaust. Similar to NF-1, the exhaust is slowed down, cooled, filtered of particulates, filtered of noble gases, and then the clean hydrogen is flared to open air. Another concept proposed by Steve Howe (currently Director of the Center for Space Nuclear Research) to simplify the NTP exhaust filtering is to run the hydrogen exhaust into boreholes underground to filter the exhaust. The two borehole site locations proposed are at the NTS and at the Idaho National Laboratory (INL). At NTS, the boreholes are 8' diameter and 1200' deep. The permeability of hydrogen through the soil and its buoyancy will allow it to rise up through the soil and allow the filtering of noble gases and radioactive particulates. The exhaust needs to be cooled to 600C before entering the borehole to avoid soil glazing. Preliminary analysis shows a small buildup of back pressure with time which depends on permeability. Noble gases entering the borehole walls deep can take a long time before reaching the surface. Other factors affecting permeability include borehole pressure, water saturation, and turbulence. Also, a possible need to pump out contaminated water collected at the bottom of the borehole. At INL, the borehole concept is slightly different. The underground borehole has openings to the soil at special depths which have impermeable interbeds above the water table and below the surface to allow the exhaust to travel horizontal between the impermeable layers. Preliminary results indicate better permeability than at NTS. The last option is total containment of the exhaust during the test run. The concept involves slowing down the flow to subsonic in a water cooled diffuser. The hydrogen is burned off in an oxygen rich afterburner with the only products being steam, oxygen, and some noble gases. A heat exchanger and water spray pulls heat from the steam and lowers the temperature for condensation. The optimum ratio between the two is being investigated, with a goal to minimize the total volume of the water hold tanks. A water tank farm collects the contaminated water. The amount of water produced from burning the hydrogen is approximately 100,000 gallons (not including cooling water) for a 25k lbf engine operating for 50 minutes. Residual gases (e.g., oxygen and some noble gases) can be captured at cryogenic levels with a liquid nitrogen cooled dewar. After a few weeks post-test, the radiation levels can drop to more favorable levels before slowly draining each capture tank and using existing filters. With today's environmental regulations, the NTP exhaust is filtered to meet 10 mrem/year exposure to the general public (at a DOE site) or 100 mrem/year (via NRC when tested elsewhere), when natural background radiation exposure to the general public is 300- 600 mrem per year. The current society feels more comfortable with filtering even lower to as low as reasonably achievable (ALARA).

Reduction of bacteria and somatic coliphages in constructed wetlands for the treatment of combined sewer overflow (retention soil filters).

PubMed

Ruppelt, Jan P; Tondera, Katharina; Schreiber, Christiane; Kistemann, Thomas; Pinnekamp, Johannes

2018-05-01

Combined sewer overflows (CSOs) introduce numerous pathogens from fecal contamination, such as bacteria and viruses, into surface waters, thus endangering human health. In Germany, retention soil filters (RSFs) treat CSOs at sensitive discharge points and can contribute to reducing these hygienically relevant microorganisms. In this study, we evaluated the extent of how dry period, series connection and filter layer thickness influence the reduction efficiency of RSFs for Escherichia coli (E. coli), intestinal enterococci (I. E.) and somatic coliphages. To accomplish this, we had four pilot scale RSFs built on a test field at the wastewater treatment plant Aachen-Soers. While two filters were replicates, the other two filters were installed in a series connection. Moreover, one filter had a thinner filtration layer than the other three. Between April 2015 and December 2016, the RSFs were loaded in 37 trials with pre-conditioned CSO after dry periods ranging from 4 to 40 days. During 17 trials, samples for microbial analysis were taken and analyzed. The series connection of two filters showed that the removal increases when two systems with a filter layer of the same height are operated in series. Since the microorganisms are exposed twice to the environmental conditions on the filter surface and in the upper filter layers, there is a greater chance for abiotic adsorption increase. The same effect could be shown when filters with different depths were compared: the removal efficiency increases as filter thickness increases. This study provides new evidence that regardless of seasonal effects and dry period, RSFs can improve hygienic situation significantly. Copyright © 2018 Elsevier GmbH. All rights reserved.

The Influence of Different Mouthpieces on Impulse Oscillometry Results.

PubMed

Dionísio, Gustavo Henrique; Dos Santos, Daniele Oliveira; Perossi, Larissa; de Paula, Mayara Holtz; de Souza, Hugo Celso Dutra; Gastaldi, Ada Clarice

2018-05-01

Impulse oscillometry is a method of airway assessment and diagnosis that provides data on lung mechanics. In the literature, studies have used different types of mouthpieces or did not describe the model used for the tests. We sought to compare the 3 most commonly described mouthpieces in terms of test results, comfort, and subject preference. Thirty-nine healthy volunteers were evaluated with spirometry and impulse oscillometry, assessing the resistance at 5 Hz and 20 Hz (R5 and R20, respectively), reactance at 5 Hz (X5), reactance area, and resonant frequency. A filter heat exchanger with a circular mouthpiece (B1), a filter heat exchanger with an oval mouthpiece (B2), and a filter heat exchanger with a circular mouthpiece coupled with a free-flow piece (B3) were compared using an acceptability and tolerance scale, and subjects noted their preference. Statistical analysis showed differences between all the mouthpieces and the predicted values for R5, R20, and X5. The mouthpiece comparison showed differences in R5 between a filter heat exchanger with an oval mouthpiece (B2) and a circular mouthpiece coupled with a free-flow piece (B3) ( P = .007); resonant frequency between a filter heat exchanger with a circular mouthpiece (B1) and a filter heat exchanger with an oval mouthpiece (B2) ( P = .004) and between a filter heat exchanger with a circular mouthpiece (B1) and a circular mouthpiece coupled with a free-flow piece (B3) ( P = .003); and reactance area between a filter heat exchanger with a circular mouthpiece (B1) and a circular mouthpiece coupled with a free-flow piece (B3) ( P = .01). In the subjective evaluation, acceptability and tolerance differences were found in the ease of carrying out the evaluation, and no difference was found with regard to the degree of discomfort. Ten subjects preferred a filter heat exchanger with a circular mouthpiece (B1), 15 preferred a filter heat exchanger with an oval mouthpiece (B2), and 14 preferred a circular mouthpiece coupled with a free-flow piece (B3). A circular mouthpiece coupled with a free-flow piece (B3) appeared to be the most suitable mouthpiece for the impulse oscillometry tests. It assured smaller impedance values for the respiratory system, and subjects expressed the most confidence in using this mouthpiece. Copyright © 2018 by Daedalus Enterprises.

Episodic soil succession on basaltic lava fields in a cool, dry environment

USGS Publications Warehouse

Vaughan, K.L.; McDaniel, P.A.; Phillips, W.M.

2011-01-01

Holocene- to late Pleistocene-aged lava flows at Craters of the Moon National Monument and Preserve provide an ideal setting to examine the early stages of soil formation under cool, dry conditions. Transects were used to characterize the amount and nature of soil cover on across basaltic lava flows ranging in age from 2.1 to 18.4 ka. Results indicate that on flows <13 ka, very shallow organic soils (Folists in Soil Taxonomy) are the dominant soil type, providing an areal coverage of up to ∼25%. On flows ≥13.9 ka, deeper mineral soils including Entisols, Aridisols, and Mollisols become dominant and the areal extent increases to ≥95% on flows older than 18.4 ka. These data suggest there are two distinct pedogenic pathways associated with lava flows of the region. The first pathway is illustrated by the younger flows, where Folists dominate. In the absence of a major source of loess, relatively little mineral material accumulates and soils provide only minor coverage of the lava flows. Our results indicate that this pathway of soil development has not changed appreciably over the past ∼10 ka. The second pedogenic pathway is illustrated by the flows older than 13.9 ka. These flows have been subject to deposition of large quantities of loess during and after the last regional glaciation, resulting in almost complete coverage. Subsequent pedogenesis has given rise to Aridisols and Mollisols with calcic and cambic horizons and mollic epipedons. This research highlights the importance of regional climate change on the evolution of Craters of the Moon soilscapes.

On-farm treatment of dairy soiled water using aerobic woodchip filters.

PubMed

Ruane, Eimear M; Murphy, Paul N C; Healy, Mark G; French, Padraig; Rodgers, Michael

2011-12-15

Dairy soiled water (DSW) is produced on dairy farms through the washing-down of milking parlours and holding areas, and is generally applied to land. However, there is a risk of nutrient loss to surface and ground waters from land application. The aim of this study was to use aerobic woodchip filters to remove organic matter, suspended solids (SS) and nutrients from DSW. This novel treatment method would allow the re-use of the final effluent from the woodchip filters to wash down yards, thereby reducing water usage and environmental risks associated with land spreading. Three replicate 100 m(2) farm-scale woodchip filters, each 1 m deep, were constructed and operated to treat DSW from 300 cows over an 11-month study duration. The filters were loaded at a hydraulic loading rate of 30 L m(-2) d(-1), applied in four doses through a network of pipes on the filter surface. Average influent concentrations of chemical oxygen demand (COD), SS and total nitrogen (TN) of 5750 ± 1441 mg L(-1), 602 ± 303 mg L(-1) and 357 ± 100 mg L(-1), respectively, were reduced by 66, 86 and 57% in the filters. Effluent nutrient concentrations remained relatively stable over the study period, indicating the effectiveness of the filter despite increasing and/or fluctuating influent concentrations. Woodchip filters are a low cost, minimal maintenance treatment system, using a renewable resource that can be easily integrated into existing farm infrastructure. Copyright © 2011 Elsevier Ltd. All rights reserved.

Optofluidic-Tunable Color Filters And Spectroscopy Based On Liquid-Crystal Microflows

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cuennet, J. G.; Vasdekis, Andreas E.; Psaltis, D.

The integration of color filters with microfluidics has attracted substantial attention in recent years, for on-chip absorption, fluorescence, or Raman analysis. We describe such tunable filters based on the micro-flow of liquid crystals. The filter operation is based on the wavelength dependent liquid crystal birefringence that can be tuned by modifying the flow velocity field in the microchannel. The latter is possible both temporally and spatially by varying the inlet pressure and the channel geometry respectively. We explored the use of these optofluidic filters for on-chip absorption spectroscopy; by integrating the distance dependent color filter with a dye-filled micro-channel, themore » absorption spectrum of a dye could be measured. Liquid crystal microflows simplify substantially the optofluidic integration, actuation and tuning of color filters for lab-on-a-chip spectroscopic applications.« less

Soil pipe flow tracer experiments: 2. Application of a transient storage zone model

USDA-ARS?s Scientific Manuscript database

Soil pipes, defined here as discrete preferential flow paths generally parallel to the slope, are important subsurface flow pathways that play a role in many soil erosion phenomena. However, limited research has been performed on quantifying and characterizing their flow and transport characteristic...

Soil phosphorus - new insights into a critical cycle across many soil functions

NASA Astrophysics Data System (ADS)

Leinweber, Peter; Zimmer, Dana

2017-04-01

The fate of phosphorus (P-) compounds in the soil - plant - water - system is linked with most soil functions such as productivity for agricultural crops, reactor for nutrient cycling, filter and buffer for water, and biodiversity. The P-compounds, mostly phosphates in a multitude of chemical bonds, may have contradicting influences on soil functions. For instance, P-concentrations may be suboptimal for crop yields but at the same time exceeding the soil filter/buffer capacity for water resources. Modern agriculture has increased this misbalance. Therefore, a better soil P management that balances all soil functions requires a deeper understanding of the P-cycling in the environment. The collaborative project "InnoSoilPhos" in the frame of the BonaRes-program of the German Federal Ministry of Education and Research (BMBF) aims at disclosing the chemical composition, biogeochemical transformations and microbiological fundamentals of P-cycling and P-transport processes across all relevant scales from atomic to catchment and landscapes. The contribution will give an overview on the project and some examples for the latest findings on P-reactions at mineral surfaces (experimental and theoretical), microorganism diversity involved in soil P-transformations, crop yield responses to P-fertilizer regimes (including new P-recycling products) and, finally, hot spots and hot moments of P-release from soils into adjoining freshwater systems. These findings allow some preliminary demands and frame conditions for an improved soil P management to better balance the soil functions and safe the global mineable P resources.

Approximate deconvolution model for the simulation of turbulent gas-solid flows: An a priori analysis

NASA Astrophysics Data System (ADS)

Schneiderbauer, Simon; Saeedipour, Mahdi

2018-02-01

Highly resolved two-fluid model (TFM) simulations of gas-solid flows in vertical periodic channels have been performed to study closures for the filtered drag force and the Reynolds-stress-like contribution stemming from the convective terms. An approximate deconvolution model (ADM) for the large-eddy simulation of turbulent gas-solid suspensions is detailed and subsequently used to reconstruct those unresolved contributions in an a priori manner. With such an approach, an approximation of the unfiltered solution is obtained by repeated filtering allowing the determination of the unclosed terms of the filtered equations directly. A priori filtering shows that predictions of the ADM model yield fairly good agreement with the fine grid TFM simulations for various filter sizes and different particle sizes. In particular, strong positive correlation (ρ > 0.98) is observed at intermediate filter sizes for all sub-grid terms. Additionally, our study reveals that the ADM results moderately depend on the choice of the filters, such as box and Gaussian filter, as well as the deconvolution order. The a priori test finally reveals that ADM is superior compared to isotropic functional closures proposed recently [S. Schneiderbauer, "A spatially-averaged two-fluid model for dense large-scale gas-solid flows," AIChE J. 63, 3544-3562 (2017)].

Sources and export of particle-borne organic matter during a monsoon flood in a catchment of northern Laos

NASA Astrophysics Data System (ADS)

Gourdin, E.; Huon, S.; Evrard, O.; Ribolzi, O.; Bariac, T.; Sengtaheuanghoung, O.; Ayrault, S.

2015-02-01

The yields of the tropical rivers of Southeast Asia supply large quantities of carbon to the ocean. The origin and dynamics of particulate organic matter were studied in the Houay Xon River catchment located in northern Laos during the first erosive flood of the rainy season in May 2012. This cultivated catchment is equipped with three successive gauging stations draining areas ranging between 0.2 and 11.6 km2 on the main stem of the permanent stream, and two additional stations draining 0.6 ha hillslopes. In addition, the sequential monitoring of rainwater, overland flow and suspended organic matter compositions was conducted at the 1 m2 plot scale during a storm. The composition of particulate organic matter (total organic carbon and total nitrogen concentrations, δ13C and δ15N) was determined for suspended sediment, soil surface (top 2 cm) and soil subsurface (gullies and riverbanks) samples collected in the catchment (n = 57, 65 and 11, respectively). Hydrograph separation of event water was achieved using water electric conductivity and δ18O measurements for rainfall, overland flow and river water base flow (n = 9, 30 and 57, respectively). The composition of particulate organic matter indicates that upstream suspended sediments mainly originated from cultivated soils labelled by their C3 vegetation cover (upland rice, fallow vegetation and teak plantations). In contrast, channel banks characterized by C4 vegetation (Napier grass) supplied significant quantities of sediment to the river during the flood rising stage at the upstream station as well as in downstream river sections. The highest runoff coefficient (11.7%), sediment specific yield (433 kg ha-1), total organic carbon specific yield (8.3 kg C ha-1) and overland flow contribution (78-100%) were found downstream of reforested areas planted with teaks. Swamps located along the main stream acted as sediment filters and controlled the composition of suspended organic matter. Total organic carbon specific yields were particularly high because they occurred during the first erosive storm of the rainy season, just after the period of slash-and-burn operations in the catchment.

Landscape Vulnerability Analysis from Historic Lower Mississippi River Flood in 2011

NASA Astrophysics Data System (ADS)

Goodwell, A. E.; Zhu, Z.; Dutta, D.; Greenberg, J.; Kumar, P.; Garcia, M. H.; Rhoads, B. L.; Parker, G.; Berretta, D.; Holmes, R. R.

2012-12-01

This study presents the results of a landscape vulnerability analysis of the Birds Point New Madrid Floodway in southeastern Missouri. The U.S. Army Corps of Engineers intentionally inundated 500 square kilometers of agricultural floodplain in May of 2011 as an emergency flood control measure. We use pre-flood (2005) and post-flood (2011) high resolution Lidar data to establish the landscape impact of the levee breach on the floodplain. The Lidar DEMs were corrected for flight line errors using a Fourier filtering technique, and then subtracted to obtain a differential DEM of erosion and deposition patterns. We use soil erosion characteristics, AVIRIS remote sensing data, and 2D floodplain modeling to analyze the three components of vulnerability: sensitivity, exposure, and adaptive capacity. HydroSed2D (Liu, Landry and García 2008), a 2D flow model, is implemented to simulate flow depths and speeds, or flood exposure, over the entire floodway, as well as smaller sections at increased resolution using a nested grid. We classify woody vegetation based on AVIRIS remote sensing data, and represent vegetated regions in the model as varied values of the Manning's n coefficient. Soil erodibility, vegetation, topography, and flow characteristics are compared to observed landscape changes within the floodplain. Overall, the floodway showed a remarkable resilience to an extreme flood event. When compared to levee breaches on similar rivers in other floods, the lack of newly deposited sediment is noticeable and likely attributable to the presence of a substantial riparian corridor between the main channel of the Mississippi River and the floodway. Although many meander scars indicating former channels of the Mississippi River are apparent in the topography, only one, known as O'Bryan Ridge, experienced high volumes of erosion and deposition due to the flooding. The vulnerability analysis supports the hypothesis this high impact is due to a combination of vulnerability factors such as high flow speed, few localized patches of vegetation, and high soil erodibility at this ridge compared to other similar meander scars. The methodology of this analysis can be used to locate regions of high vulnerability in future floodplain management and flood control, and mitigate potentially catastrophic landscape change.

Surface runoff and retention of transported pollutants in strips of riparian vegetation with and without trees

NASA Astrophysics Data System (ADS)

Giaccio, Gustavo; Laterra, Pedro; Aparicio, Virginia; Costa, Jose Luis

2017-04-01

In this study, some aspects related to the effect of the crack willow (Salix fragilis L.) invasion on the reduction of runoff and sediment retention, glyphosate, nitrogen and phosphorus in riparian environments with herbaceous vegetation of the Austral Pampa of Argentina were analysed. In order to evaluate the influence of the willows on the filtering mechanisms, surface runoff simulation experiments were carried out in plots of 1.5 m x 2.5 m in environments characterized by the presence vs. the absence of willows. In spite of the small length of the experimental plots, glyphosate retention in the tree-less plots reached 73.6%, a higher value than that recorded in tree stands (43.8%). However, sediment, nitrogen and phosphorus retention did not vary significantly between treatments. On the other hand, the reduction of the volume of runoff in the sites with trees reached 63%, a superior value to the one registered in strips without trees (31%). The presence of trees only significantly modified the biophysical properties of hydraulic conductivity, surface roughness, aerial biomass and soil moisture, compared to areas with no trees. Partial correlation analysis for both tree and no-tree environments showed that the reduction in runoff volume increased significantly with hydraulic conductivity, soil sand content and depth at the water table, and decreased with apparent density, soil moisture and the slope of the riverbank. However, sediment retention increased significantly with aerial, mulch and root biomass and decreased with the slope of the riparian strip. Glyphosate retention increased significantly with sediment retention and decreased with the slope of the riparian strip and the mulch biomass. Nitrogen retention increased with the reduction of runoff flow, soil hydraulic conductivity and depth to the water table and decreased with slope and sediment retention. While, phosphorus retention increased with sediment retention and decreased with slope and soil content of soils. However, the mechanisms involved in the differential effect of the vegetation with or without trees could not be explained. This work emphasizes the importance of the ecosystem function of glyphosate filtration of riparian environments covered by herbaceous vegetation in front of the increasing intensification of agriculture. On the other hand, in the context of agro ecosystems and agricultural landscapes the presence of trees contributes to the reduction of the flow of runoff, although these sub compensate in relation to the sites without trees, considering the balance between flow and concentration.

Effects of soil water availability on water fluxes in winter wheat

NASA Astrophysics Data System (ADS)

Cai, G.; Vanderborght, J.; Langensiepen, M.; Vereecken, H.

2014-12-01

Quantifying soil water availability in water-limited ecosystems on plant water use continues to be a practical problem in agronomy. Transpiration which represents plant water demand is closely in relation to root water uptake in the root zone and sap flow in plant stems. However, few studies have been concentrated on influences of soil moisture on root water uptake and sap flow in crops. This study was undertaken to investigate (i) whether root water uptake and sap flow correlate with the transpiration estimated by the Penman-Monteith model for winter wheat(Triticum aestivum), and (ii) for which soil water potentials in the root zone, the root water uptake and sap flow rates in crop stems would be reduced. Therefore, we measured sap flow velocities by an improved heat-balance approach (Langensiepen et al., 2014), calculated crop transpiration by Penman-Monteith model, and simulated root water uptake by HYDRUS-1D on an hourly scale for different soil water status in winter wheat. In order to assess the effects of soil water potential on root water uptake and sap flow, an average soil water potential was calculated by weighting the soil water potential at a certain depth with the root length density. The temporal evolution of root length density was measured using horizontal rhizotubes that were installed at different depths.The results showed that root water uptake and sap flow matched well with the computed transpiration by Penman-Monteith model in winter wheat when the soil water potential was not limiting root water uptake. However, low soil water content restrained root water uptake, especially when soil water potential was lower than -90 kPa in the top soil. Sap flow in wheat was not affected by the observed soil water conditions, suggesting that stomatal conductance was not sensitive to soil water potentials. The effect of drought stress on root water uptake and sap flow in winter wheat was only investigated in a short time (after anthesis). Further research could focus on a long time (e.g. from vegetation to maturity) effect under different soil water conditions, such as irrigated, sheltered and normal status. Langensiepen, M., Kupisch, M., Graf, A., Schmidt, M. and Ewert, F., 2014. Improving the stem heat balance method for determining sap-flow in wheat. Agricultural and Forest Meteorology, 186: 34-42.

Filtering analysis of a direct numerical simulation of the turbulent Rayleigh-Benard problem

NASA Technical Reports Server (NTRS)

Eidson, T. M.; Hussaini, M. Y.; Zang, T. A.

1990-01-01

A filtering analysis of a turbulent flow was developed which provides details of the path of the kinetic energy of the flow from its creation via thermal production to its dissipation. A low-pass spatial filter is used to split the velocity and the temperature field into a filtered component (composed mainly of scales larger than a specific size, nominally the filter width) and a fluctuation component (scales smaller than a specific size). Variables derived from these fields can fall into one of the above two ranges or be composed of a mixture of scales dominated by scales near the specific size. The filter is used to split the kinetic energy equation into three equations corresponding to the three scale ranges described above. The data from a direct simulation of the Rayleigh-Benard problem for conditions where the flow is turbulent are used to calculate the individual terms in the three kinetic energy equations. This is done for a range of filter widths. These results are used to study the spatial location and the scale range of the thermal energy production, the cascading of kinetic energy, the diffusion of kinetic energy, and the energy dissipation. These results are used to evaluate two subgrid models typically used in large-eddy simulations of turbulence. Subgrid models attempt to model the energy below the filter width that is removed by a low-pass filter.

Fine PM measurements: personal and indoor air monitoring.

PubMed

Jantunen, M; Hänninen, O; Koistinen, K; Hashim, J H

2002-12-01

This review compiles personal and indoor microenvironment particulate matter (PM) monitoring needs from recently set research objectives, most importantly the NRC published "Research Priorities for Airborne Particulate Matter (1998)". Techniques and equipment used to monitor PM personal exposures and microenvironment concentrations and the constituents of the sampled PM during the last 20 years are then reviewed. Development objectives are set and discussed for personal and microenvironment PM samplers and monitors, for filter materials, and analytical laboratory techniques for equipment calibration, filter weighing and laboratory climate control. The progress is leading towards smaller sample flows, lighter, silent, independent (battery powered) monitors with data logging capacity to store microenvironment or activity relevant sensor data, advanced flow controls and continuous recording of the concentration. The best filters are non-hygroscopic, chemically pure and inert, and physically robust against mechanical wear. Semiautomatic and primary standard equivalent positive displacement flow meters are replacing the less accurate methods in flow calibration, and also personal sampling flow rates should become mass flow controlled (with or without volumetric compensation for pressure and temperature changes). In the weighing laboratory the alternatives are climatic control (set temperature and relative humidity), and mechanically simpler thermostatic heating, air conditioning and dehumidification systems combined with numerical control of temperature, humidity and pressure effects on flow calibration and filter weighing.

Turbulence measurements in an Alpine valley: The CividatEX Experiment case

NASA Astrophysics Data System (ADS)

Falocchi, Marco; Barontini, Stefano; Zardi, Dino; Ranzi, Roberto

2015-04-01

Results regarding the analysis of turbulence data, collected during Summer 2012, 2013 and 2014 in the framework of the CividatEX Experiment, are presented. The CividatEX Experiment, kicked off in July 2012 and still ongoing, aims at quantifying the mass and energy fluxes exchanged at the soil-atmosphere interface in an Alpine valley. A micro-meteorological station, equipped with standard meteorological devices, four TDR probes, soil heat-flux plate, soil thermometers and an eddy-covariance system (sonic anemometer and gas analyser), was installed on the valley floor of Valle Camonica at Cividate Camuno (274ma.s.l., Oglio river basin, Central Italian Alps). The experimental site is a gentle-sloping Technosol lawn, covered by common grass and surrounded by a steep hill (E and S) and by an anthropized landscape (W and N). Such complex terrain conditions affect the wind regime that, especially during fair weather conditions, is mainly regulated by thermally-driven winds. At least three winds were recognized, i.e. (1) the local wind Óra del Sebino (WSW, speed ranging from 2 to 4 ms-1), which rises the valley from Lake Iseo (Sebino) in the afternoon; (2) a katabatic flow with small speed (from 0.5 to 1.5 ms-1) blowing down the hillslope (directions ranging from E to SE) since the evening to the sunrise; and (3) an up-slope cross-valley wind (W, from 0.5 to 1.5 ms-1) flowing in the late morning. The 15 and 30-minutes eddy-covariance fluxes of momentum (τ), latent heat (λE) and sensible heat (Hs) were estimated using the software EddyPro. The surface energy imbalance was calculated as 1 - (λE + Hs)/(Rn - G), where Rn and G are the net radiation and the ground heat flux respectively. For all the three data-sets the imbalance assumes values ranging between 0.3 and 0.4. A dependence of its magnitude from the atmospheric stability and from the blowing wind was observed. In fact the imbalance reduces during unstable conditions, when the Óra occurs, and it increases during the night when the wind speed is small and stable conditions are approached. The separation of the turbulent components from the low-frequency unsteadiness of the mean-flow was investigated by means of three different approaches, that are the block average, the linear detrending and a digital recursive-filtering technique. The obtained dimensionless standard deviations of the wind velocities and of the temperature fluctuations were analyzed in the framework of the Monin-Obukhov similarity theory by checking their thickening on the similarity relationships. Due to the presence of meaningful unsteadiness during the investigated time-windows, the block average and the linear detrending were less effective than the recursive-filtering procedure at separating the turbulent fluctuations from the mean-flow.

Numerical Modeling of Coupled Water Flow and Heat Transport in Soil and Snow

NASA Astrophysics Data System (ADS)

Kelleners, T.

2015-12-01

A numerical model is developed to calculate coupled water flow and heat transport in seasonally frozen soil and snow. Both liquid water flow and water vapor flow are included. The effect of dissolved ions on soil water freezing point depression is included by combining an expression for osmotic head with the Clapeyron equation and the van Genuchten soil water retention function. The coupled water flow and heat transport equations are solved using the Thomas algorithm and Picard iteration. Ice pressure is always assumed zero and frost heave is neglected. The new model is tested using data from a high-elevation rangeland soil that is subject to significant soil freezing and a mountainous forest soil that is snow-covered for about 8 months of the year. Soil hydraulic parameters are mostly based on measurements and only vegetation parameters are fine-tuned to match measured and calculated soil water content, soil & snow temperature, and snow height. Modeling statistics for both systems show good performance for temperature, intermediate performance for snow height, and relatively low performance for soil water content, in accordance with earlier results with an older version of the model.

Optimization of the cleaning process on a pilot filtration setup for waste water treatment accompanied by flow visualization

NASA Astrophysics Data System (ADS)

Bílek, Petr; Hrůza, Jakub

2018-06-01

This paper deals with an optimization of the cleaning process on a liquid flat-sheet filter accompanied by visualization of the inlet side of a filter. The cleaning process has a crucial impact on the hydrodynamic properties of flat-sheet filters. Cleaning methods avoid depositing of particles on the filter surface and forming a filtration cake. Visualization significantly helps to optimize the cleaning methods, because it brings new overall view on the filtration process in time. The optical method, described in the article, enables to see flow behaviour in a thin laser sheet on the inlet side of a tested filter during the cleaning process. Visualization is a strong tool for investigation of the processes on filters in details and it is also possible to determine concentration of particles after an image analysis. The impact of air flow rate, inverse pressure drop and duration on the cleaning mechanism is investigated in the article. Images of the cleaning process are compared to the hydrodynamic data. The tests are carried out on a pilot filtration setup for waste water treatment.

Fiber length and orientation prevent migration in fluid filters

NASA Technical Reports Server (NTRS)

Reiman, P. A.

1966-01-01

Stainless steel fiber web filter resists fiber migration which causes contamination of filtered fluids. This filter is capable of holding five times more particulate matter before arbitrary cutoff pressure drop and shows excellent retention in fuel flow at high rates.

Treating landfill gas hydrogen sulphide with mineral wool waste (MWW) and rod mill waste (RMW).

PubMed

Bergersen, Ove; Haarstad, Ketil

2014-01-01

Hydrogen sulphide (H2S) gas is a major odorant at municipal landfills. The gas can be generated from different waste fractions, for example demolition waste containing gypsum based plaster board. The removal of H2S from landfill gas was investigated by filtering it through mineral wool waste products. The flow of gas varied from 0.3 l/min to 3.0 l/min. The gas was typical for landfill gas with a mean H2S concentration of ca. 4500 ppm. The results show that the sulphide gas can effectively be removed by mineral wool waste products. The ratios of the estimated potential for sulphide precipitation were 19:1 for rod mill waste (RMW) and mineral wool waste (MWW). A filter consisting of a mixture of MWW and RMW, with a vertical perforated gas tube through the center of filter material and with a downward gas flow, removed 98% of the sulfide gas over a period of 80 days. A downward gas flow was more efficient in contacting the filter materials. Mineral wool waste products are effective in removing hydrogen sulphide from landfill gas given an adequate contact time and water content in the filter material. Based on the estimated sulphide removal potential of mineral wool and rod mill waste of 14 g/kg and 261 g/kg, and assuming an average sulphide gas concentration of 4500 ppm, the removal capacity in the filter materials has been estimated to last between 11 and 308 days. At the studied location the experimental gas flow was 100 times less than the actual gas flow. We believe that the system described here can be upscaled in order to treat this gas flow. Copyright © 2013 Elsevier Ltd. All rights reserved.

Subgrid-scale effects in compressible variable-density decaying turbulence

DOE PAGES

GS, Sidharth; Candler, Graham V.

2018-05-08

We present that many turbulent flows are characterized by complex scale interactions and vorticity generation caused by compressibility and variable-density effects. In the large-eddy simulation of variable-density flows, these processes manifest themselves as subgrid-scale (SGS) terms that interact with the resolved-scale flow. This paper studies the effect of the variable-density SGS terms and quantifies their relative importance. We consider the SGS terms appearing in the density-weighted Favre-filtered equations and in the unweighted Reynolds-filtered equations. The conventional form of the Reynolds-filtered momentum equation is complicated by a temporal SGS term; therefore, we derive a new form of the Reynolds-filtered governing equationsmore » that does not contain this term and has only double-correlation SGS terms. The new form of the filtered equations has terms that represent the SGS mass flux, pressure-gradient acceleration and velocity-dilatation correlation. To evaluate the dynamical significance of the variable-density SGS effects, we carry out direct numerical simulations of compressible decaying turbulence at a turbulent Mach number of 0.3. Two different initial thermodynamic conditions are investigated: homentropic and a thermally inhomogeneous gas with regions of differing densities. The simulated flow fields are explicitly filtered to evaluate the SGS terms. The importance of the variable-density SGS terms is quantified relative to the SGS specific stress, which is the only SGS term active in incompressible constant-density turbulence. It is found that while the variable-density SGS terms in the homentropic case are negligible, they are dynamically significant in the thermally inhomogeneous flows. Investigation of the variable-density SGS terms is therefore important, not only to develop variable-density closures but also to improve the understanding of scale interactions in variable-density flows.« less

Subgrid-scale effects in compressible variable-density decaying turbulence

DOE Office of Scientific and Technical Information (OSTI.GOV)

GS, Sidharth; Candler, Graham V.

We present that many turbulent flows are characterized by complex scale interactions and vorticity generation caused by compressibility and variable-density effects. In the large-eddy simulation of variable-density flows, these processes manifest themselves as subgrid-scale (SGS) terms that interact with the resolved-scale flow. This paper studies the effect of the variable-density SGS terms and quantifies their relative importance. We consider the SGS terms appearing in the density-weighted Favre-filtered equations and in the unweighted Reynolds-filtered equations. The conventional form of the Reynolds-filtered momentum equation is complicated by a temporal SGS term; therefore, we derive a new form of the Reynolds-filtered governing equationsmore » that does not contain this term and has only double-correlation SGS terms. The new form of the filtered equations has terms that represent the SGS mass flux, pressure-gradient acceleration and velocity-dilatation correlation. To evaluate the dynamical significance of the variable-density SGS effects, we carry out direct numerical simulations of compressible decaying turbulence at a turbulent Mach number of 0.3. Two different initial thermodynamic conditions are investigated: homentropic and a thermally inhomogeneous gas with regions of differing densities. The simulated flow fields are explicitly filtered to evaluate the SGS terms. The importance of the variable-density SGS terms is quantified relative to the SGS specific stress, which is the only SGS term active in incompressible constant-density turbulence. It is found that while the variable-density SGS terms in the homentropic case are negligible, they are dynamically significant in the thermally inhomogeneous flows. Investigation of the variable-density SGS terms is therefore important, not only to develop variable-density closures but also to improve the understanding of scale interactions in variable-density flows.« less

Unsaturated flow processes in structurally-variable pathways in wildfire-affected soils and ash

NASA Astrophysics Data System (ADS)

Ebel, B. A.

2016-12-01

Prediction of flash flood and debris flow generation in wildfire-affected soils and ash hinges on understanding unsaturated flow processes. Water resources issues, such as groundwater recharge, also rely on our ability to quantify subsurface flow. Soil-hydraulic property data provide insight into unsaturated flow processes and timescales. A literature review and synthesis of existing data from the literature for wildfire-affected soils, including ash and unburned soils, facilitated calculating metrics and timescales of hydrologic response related to infiltration and surface runoff generation. Sorptivity (S) and the Green-Ampt wetting front parameter (Ψf) were significantly lower in burned soils compared to unburned soils, while field-saturated hydraulic conductivity (Kfs) was not significantly different. The magnitude and duration of the influence of capillarity was substantially reduced in burned soils, leading to faster ponding times in response to rainfall. Ash had large values of S and Kfs compared to unburned and burned soils but intermediate values of Ψf, suggesting that ash has long ponding times in response to rainfall. The ratio of S2/Kfs was nearly constant ( 100 mm) for unburned soils, but was more variable in burned soils. Post-wildfire changes in this ratio suggested that unburned soils had a balance between gravity and capillarity contributions to infiltration, which may depend on soil organic matter, while burning shifted infiltration more towards gravity contributions by reducing S. Taken together, the changes in post-wildfire soil-hydraulic properties increased the propensity for surface runoff generation and may have enhanced subsurface preferential flow through pathways altered by wildfire.

Characterization of the relationship between ceramic pot filter water production and turbidity in source water.

PubMed

Salvinelli, Carlo; Elmore, A Curt; Reidmeyer, Mary R; Drake, K David; Ahmad, Khaldoun I

2016-11-01

Ceramic pot filters represent a common and effective household water treatment technology in developing countries, but factors impacting water production rate are not well-known. Turbidity of source water may be principal indicator in characterizing the filter's lifetime in terms of water production capacity. A flow rate study was conducted by creating four controlled scenarios with different turbidities, and influent and effluent water samples were tested for total suspended solids and particle size distribution. A relationship between average flow rate and turbidity was identified with a negative linear trend of 50 mLh -1 /NTU. Also, a positive linear relationship was found between the initial flow rate of the filters and average flow rate calculated over the 23 day life of the experiment. Therefore, it was possible to establish a method to estimate the average flow rate given the initial flow rate and the turbidity in the influent water source, and to back calculate the maximum average turbidity that would need to be maintained in order to achieve a specific average flow rate. However, long-term investigations should be conducted to assess how these relationships change over the expected CPF lifetime. CPFs rejected fine suspended particles (below 75 μm), especially particles with diameters between 0.375 μm and 10 μm. The results confirmed that ceramic pot filters are able to effectively reduce turbidity, but pretreatment of influent water should be performed to avoid premature failure. Copyright © 2016 Elsevier Ltd. All rights reserved.

A Catchment Systems Engineering (CSE) approach to managing intensively farmed land

NASA Astrophysics Data System (ADS)

Jonczyk, Jennine; Quinn, Paul; Barber, Nicholas; Wilkinson, Mark; ODonnell, Greg

2014-05-01

Rural land management practices can have a significant impact on the hydrological and nutrient dynamics within a catchment which can dramatically alter the way it processes water, exacerbating nutrient losses from the system. A collaborative and holistic approach for managing potential conflicts between land management activity for food production alongside the aspiration to achieve good water quality and the need to make space for water can ensure the long-term sustainability of our agricultural catchments. Catchment System Engineering (CSE) is an interventionist approach to altering the catchment scale runoff regime through the manipulation of hydrological flow pathways throughout the catchment. By targeting hydrological flow pathways at source, such as overland flow, field drain and ditch function, a significant component of the runoff generation can be managed, greatly reducing erosive soil losses. Coupled with management of farm nutrients at source many runoff attenuation features or measures can be co-located to achieve benefits for water quality. Examples of community-led mitigation measures using the CSE approach will be presented from two catchments in Northumberland, Northern England, that demonstrate the generic framework for identification of multipurpose features that slow, store and filter runoff at strategic locations in the landscape. Measures include within-field barriers, edge of field traps and within-field sediment filters and sediment traps which demonstrate how sediment can be trapped locally (including silt and clay fractions) and be recovered for use back on the land. Deliverables from this CSE approach includes the reduction of downstream flood risk and capturing of sediment and associated nutrients. The CSE approach allows for a more natural flood and nutrient management approach which helps to restore vital catchment functions to re-establish a healthy catchment system.

Construction of Low Dissipative High Order Well-Balanced Filter Schemes for Non-Equilibrium Flows

NASA Technical Reports Server (NTRS)

Wang, Wei; Yee, H. C.; Sjogreen, Bjorn; Magin, Thierry; Shu, Chi-Wang

2009-01-01

The goal of this paper is to generalize the well-balanced approach for non-equilibrium flow studied by Wang et al. [26] to a class of low dissipative high order shock-capturing filter schemes and to explore more advantages of well-balanced schemes in reacting flows. The class of filter schemes developed by Yee et al. [30], Sjoegreen & Yee [24] and Yee & Sjoegreen [35] consist of two steps, a full time step of spatially high order non-dissipative base scheme and an adaptive nonlinear filter containing shock-capturing dissipation. A good property of the filter scheme is that the base scheme and the filter are stand alone modules in designing. Therefore, the idea of designing a well-balanced filter scheme is straightforward, i.e., choosing a well-balanced base scheme with a well-balanced filter (both with high order). A typical class of these schemes shown in this paper is the high order central difference schemes/predictor-corrector (PC) schemes with a high order well-balanced WENO filter. The new filter scheme with the well-balanced property will gather the features of both filter methods and well-balanced properties: it can preserve certain steady state solutions exactly; it is able to capture small perturbations, e.g., turbulence fluctuations; it adaptively controls numerical dissipation. Thus it shows high accuracy, efficiency and stability in shock/turbulence interactions. Numerical examples containing 1D and 2D smooth problems, 1D stationary contact discontinuity problem and 1D turbulence/shock interactions are included to verify the improved accuracy, in addition to the well-balanced behavior.

A model-data fusion analysis for examining the response of carbon exchange to environmental variation in crop field

NASA Astrophysics Data System (ADS)

Yokozawa, M.; Sakurai, G.; Ono, K.; Mano, M.; Miyata, A.

2011-12-01

Agricultural activities, cultivating crops, managing soil, harvesting and post-harvest treatments, are not only affected from the surrounding environment but also change the environment reversely. The changes in environment, temperature, radiation and precipitation, brings changes in crop productivity. On the other hand, the status of crops, i.e. the growth and phenological stage, change the exchange of energy, H2O and CO2 between crop vegetation surface and atmosphere. Conducting the stable agricultural harvests, reducing the Greenhouse Effect Gas (GHG) emission and enhancing carbon sequestration in soil are preferable as a win-win activity. We conducted model-data fusion analysis for examining the response of cropland-atmosphere carbon exchange to environmental variation. The used model consists of two sub models, paddy rice growth sub-model and soil decomposition sub-model. The crop growth sub-model mimics the rice plant growth processes including formation of reproductive organs as well as leaf expansion. The soil decomposition sub-model simulates the decomposition process of soil organic carbon. Assimilating the data on the time changes in CO2 flux measured by eddy covariance method, rice plant biomass, LAI and the final yield with the model, the parameters were calibrated using a stochastic optimization algorithm with a particle filter. The particle filter, which is one of Monte Carlo filters, enable us to evaluating time changes in parameters based on the observed data until the time and to make prediction of the system. Iterative filtering and prediction with changing parameters and/or boundary condition enable us to obtain time changes in parameters governing the crop production as well as carbon exchange. In this paper, we applied the model-data fusion analysis to the two datasets on paddy rice field sites in Japan: only a single rice cultivation, and a single rice and wheat cultivation. We focused on the parameters related to crop production as well as soil carbon storage. As a result, the calibrated model with estimated parameters could accurately predict the NEE flux in the subsequent years (Fig.1). The temperature sensitivity, Q10s in the decomposition rate of soil organic carbon (SOC) were obtained as 1.4 for no cultivation period and 2.9 for cultivation period (submerged soil condition).

Development of dissolved air flotation technology from the first generation to the newest (third) one (DAF in turbulent flow conditions).

PubMed

Kiuru, H J

2001-01-01

This paper gives a brief description of the development of dissolved air flotation DAF (or so-called high pressure flotation) as an unit operation for removal of solids in water and wastewater treatment during the last 80 years up to this time. The first DAF-systems used in the water industry were the ADKA and Sveen-Pedersen ones from the 1920s. Some of these are still in use. The tanks in which the flotation phenomenon takes place in these systems are very shallow and narrow as well as rather long. The flow rate of water is some 2-3 m/h (at most less than 5 m/h only) and there is a very thin micro-bubble blanket below the water surface between the dry sludge blanket on that and the clarified water which flows almost horizontally below the bubble blanket toward the end of the tanks to be taken out there from near the bottom. The second generation of DAF was introduced in the 1960s and these units are widely in use today. Their tanks are almost square ones having usually a little bit more length than breadth. They are rather deep, too. There is an under-flow wall in front of the back wall of the units having a narrow horizontal gap on the bottom of the tanks for letting out the clarified water from the flotation space. The flow rate of water is usually 5-7 m/h or at most less than 10 m/h. The direction of flow is 30-45 degrees below the horizontal. There is a rather thick micro-bubble bed at the beginning of the tank below the dry sludge blanket. This bubble-bed becomes clearly thinner, when going toward the end of the tank. There are also round DAF tanks which are based on the same hydraulic principles as the rectangular ones presented above. A special application of DAF called the flotation filter was invented at the very end of the 1960s. It is a combination of flotation and rapid sand filtration, both of those being placed in the same tank. Flotation takes place in the upper part of the tank and the filter has been placed in the lower part of it. The direction of water flow is now vertically down from the free surface of water in the tank toward the deep-bed filter. This controls the direction of flow in the flotation space of the tank above the filter bed. The flow rate of water in flotation filters may be 10-15 m/h, but the flow conditions are still laminar. It is the threat that the head-loss of filters would grow too rapidly which in practice is limiting the hydraulic flow rate of flotation filters in this area. The third generation of DAF has been developed at the end of the 1990s. The operational idea is based on that of the flotation filter. The filter bed on the bottom of the tank has been replaced by a thin stiff plate with plenty of round orifices throughout the plate. This plate, having a very much lower flowing resistance than a sand filter can have, controls the vertical flow of water in the flotation space above the plate and distributes it evenly throughout the horizontal cross-section of the tank. The flotation tank is almost square seen from above and its depth is clearly more than the length and breadth of it. This kind of flotation unit can be operated with flow rates of water in the range 25-40 m/l. Even a flow rate of more than 60 m/h has been reported from this kind of DAF-units. There is no risk of clogging of the plate by suspended solids which could limit the flow rate. This is to say that it is possible to operate DAF also in turbulent flow conditions. The depth of the micro-bubble bed below the surface of water can be 1.5-2.5 m. There actually is a continuously regenerated micro-bubble bed in the tank filtering water which is going through this bed. The lower surface of the micro-bubble bed is really a horizontal one a little bit above the plate controlling the flow in the flotation space. The clarified water below the micro-bubble bed is totally clear. It can be said that in this case the removal of suspended solids takes place much more by filtering water by a deep-bed micro-bubble filter than by attaching micro-bubbles onto solids, when both of these are mixed with each other in the inlet shaft of the flotation unit, because the retention time of water in the inlet shaft is very short indeed.

[Analysis of hydrodynamics parameters of runoff erosion and sediment-yielding on unpaved road].

PubMed

Huang, Peng-Fei; Wang, Wen-Long; Luo, Ting; Wang, Zhen; Wang, Zheng-Li; Li, Ren

2013-02-01

By the method of field runoff washout experiment, a simulation study was conducted on the relationships between the soil detachment rate and the hydrodynamic parameters on unpaved road, and the related quantitative formulas were established. Under the conditions of different flow discharges and road gradients, the averaged soil detachment rate increased with increasing flow discharge and road gradient, and the relationships between them could be described by a power function. As compared with road gradient, flow discharge had greater effects on the soil detachment rate. The soil detachment rate had a power relation with water flow velocity and runoff kinetic energy, and the runoff kinetic energy was of importance to the soil detachment rate. The soil detachment rate was linearly correlated with the unit runoff kinetic energy. The averaged soil erodibility was 0.120 g m-1.J-F-1, and the averaged critical unit runoff kinetic energy was 2.875 g.m-1.J-1. Flow discharge, road gradient, and unit runoff kinetic energy could be used to accurately describe the soil erosion process and calculate the soil erosion rate on unpaved road.

Methodology for modeling the microbial contamination of air filters.

PubMed

Joe, Yun Haeng; Yoon, Ki Young; Hwang, Jungho

2014-01-01

In this paper, we propose a theoretical model to simulate microbial growth on contaminated air filters and entrainment of bioaerosols from the filters to an indoor environment. Air filter filtration and antimicrobial efficiencies, and effects of dust particles on these efficiencies, were evaluated. The number of bioaerosols downstream of the filter could be characterized according to three phases: initial, transitional, and stationary. In the initial phase, the number was determined by filtration efficiency, the concentration of dust particles entering the filter, and the flow rate. During the transitional phase, the number of bioaerosols gradually increased up to the stationary phase, at which point no further increase was observed. The antimicrobial efficiency and flow rate were the dominant parameters affecting the number of bioaerosols downstream of the filter in the transitional and stationary phase, respectively. It was found that the nutrient fraction of dust particles entering the filter caused a significant change in the number of bioaerosols in both the transitional and stationary phases. The proposed model would be a solution for predicting the air filter life cycle in terms of microbiological activity by simulating the microbial contamination of the filter.

Optical monitor for observing turbulent flow

DOEpatents

Albrecht, Georg F.; Moore, Thomas R.

1992-01-01

The present invention provides an apparatus and method for non-invasively monitoring turbulent fluid flows including anisotropic flows. The present invention uses an optical technique to filter out the rays travelling in a straight line, while transmitting rays with turbulence induced fluctuations in time. The output is two dimensional, and can provide data regarding the spectral intensity distribution, or a view of the turbulence in real time. The optical monitor of the present invention comprises a laser that produces a coherent output beam that is directed through a fluid flow, which phase-modulates the beam. The beam is applied to a temporal filter that filters out the rays in the beam that are straight, while substantially transmitting the fluctuating, turbulence-induced rays. The temporal filter includes a lens and a photorefractive crystal such as BaTiO.sub.3 that is positioned in the converging section of the beam near the focal plane. An imaging system is used to observe the filtered beam. The imaging system may take a photograph, or it may include a real time camera that is connected to a computer. The present invention may be used for many purposes including research and design in aeronautics, hydrodynamics, and combustion.

Vadose zone transport of natural and synthetic estrogen hormones at Penn State's "Living Filter" wastewater irrigation site

USDA-ARS?s Scientific Manuscript database

The increase in endocrine disrupting compounds (EDCs) in the environment has generated new research focused on the behavior of these compounds in natural soil and water ecosystems. To understand how estrogens behave in the soil environment as a result of 25+ years of wastewater irrigation, soils fro...

Results from Assimilating AMSR-E Soil Moisture Estimates into a Land Surface Model Using an Ensemble Kalman Filter in the Land Information System

NASA Technical Reports Server (NTRS)

Blankenship, Clay B.; Crosson, William L.; Case, Jonathan L.; Hale, Robert

2010-01-01

Improve simulations of soil moisture/temperature, and consequently boundary layer states and processes, by assimilating AMSR-E soil moisture estimates into a coupled land surface-mesoscale model Provide a new land surface model as an option in the Land Information System (LIS)

Functional units and lead topologies: a hierarchical framework for observing and modeling the interplay of structures, storage dynamics and integral mass and energy flows in lower mesoscale catchments

NASA Astrophysics Data System (ADS)

Zehe, Erwin; Jackisch, Conrad; Blume, Theresa; Haßler, Sibylle; Allroggen, Niklas; Tronicke, Jens

2013-04-01

The CAOS Research Unit recently proposed a hierarchical classification scheme to subdivide a catchment into what we vaguely name classes of functional entities that puts the gradients driving mass and energy flows and their controls on top of the hierarchy and the arrangement of landscape attributes controlling flow resistances along these driving gradients (for instance soil types and apparent preferential pathways) at the second level. We name these functional entities lead topology classes, to highlight that they are characterized by a spatially ordered arrangement of landscape elements along a superordinate driving gradient. Our idea is that these lead topology classes have a distinct way how their structural and textural architecture controls the interplay of storage dynamics and integral response behavior that is typical for all members of a class, but is dissimilar between different classes. This implies that we might gain exemplary understanding of the typical dynamic behavior of the class, when thoroughly studying a few class members. We propose that the main integral catchment functions mass export and drainage, mass redistribution and storage, energy exchange with the atmosphere, as well as energy redistribution and storage - result from spatially organized interactions of processes within lead topologies that operate at different scale levels and partly dominate during different conditions. We distinguish: 1) Lead topologies controlling the land surface energy balance during radiation driven conditions at the plot/pedon scale level. In this case energy fluxes dominate and deplete a vertical temperature gradient that is build up by depleting a gradient in radiation fluxes. Water is a facilitator in this concert due to the high specific heat of vaporization. Slow vertical water fluxes in soil dominate, which are driven by vertical gradients in atmospheric water potential, chemical potential in the plant and in soil hydraulic potentials. 2) Lead topologies controlling fast drainage and generation stream flow during rainfall events at the hillslope scale level: Fast vertical and lateral mass fluxes dominate. They are driven by vertical and lateral gradients in pressure heads which build up by depleting the kinetic energy/velocity gradient of rainfall when it hits the ground or of vertical subsurface flows that "hit" a layer of low permeability. 3) Lead topologies controlling slow drainage and its supply, and thus creating memory at the catchment scale level: These are the groundwater system and the stream including the riparian zone. Permanent lateral water flows dominate that are driven by permanently active lateral gradients in pressure heads. Event scale stream flow generation and energy exchange with the atmospheric boundary layer are organized by the first two types of lead topologies, and their dominance changes with prevailing type of boundary conditions. We furthermore propose that lead topologies at the plot and the hillslope scale levels can be further subdivided into least functional entities we name call classes of elementary functional units. These classes of elementary functional units co-evolved being exposed to similar superordinate vertical gradients in a self-reinforcing manner. Being located either at the hilltop (sediment source area), midslope (sediment transport area) or hillfoot/riparian zone (sediment deposit area) they experienced similar weathering processes (past water, energy and nutrient flows), causing formation of similar soil texture in different horizons. This implies, depending on hillslope position and aspect, formation of distinct niches (with respect to water, nutrient and sun light availability) and thus "similar filters" to select distinct natural communities of animal and vegetation species. This in turn implies similarity with respect to formation of biotic flow networks (ant-, worm-, mole- and whole burrow systems, as well as root systems), which feeds back on vertical and lateral water/mass and thermal energy flows and so on. The idea is that members of EFU classes interact within lead topologies along a hierarchy of driving potential gradients and that these interactions are mediated by a hierarchy of connected flow networks like macropores, root networks or lateral pipe systems. We hypothesize that members of a functional unit class are similar with respect to the time invariant controls of the vertical gradients (soil hydraulic potentials, soil temperature, plant water potential) and the flow resistances in vertical direction (plant and soil albedo, soil hydraulic and thermal conductivity, vertical macropore networks). This implies that members of an EFU class behave functionally similar at least with respect to vertical flows of water and heat: we may gain exemplary understanding of the typical dynamic behavior of the class, by thoroughly studying a few class members. In the following we will thus use the term "elementary functional units, EFUs" and "elementary functional unit class, EFU class" as synonyms. We propose that a thorough understanding of the behavior of a few representatives of the most important EFU classes and of their interactions within a hierarchy of lead topology classes is sufficient for understanding and distributed modeling of event scale stream flow production under rainfall driven conditions and energy exchange with the atmosphere under radiation driven conditions. Good and not surprising news is that lead topologies controlling stream flow contribution, are an interconnected, ordered arrangement of the lead topologies that control energy exchange. We suggests that a combination of the related model approaches which simplified but physical based approaches to simulate dynamics in the saturated zone, riparian zone and the river network results in a structurally more adequate model framework for catchments of organized complexity. The feasibility of this concept is currently tested in the Attert catchment by setting up pseudo replica of field experiments and a distributed monitoring network in several members of first guess EFUs and superordinate lead topology classes. We combine geophysical and soil physical survey, artificial tracer tests and analysis of stable isotopes and ecological survey with distributed sensor clusters that permanently monitor meteorological variables, soil moisture and matric potential, piezometric heads etc. Within the proposed study we will present first results especially from the sensor clusters and geophysical survey. By using geostatistical methods we will work out to which extend members within a candidate EFU class are similar with respect to subsurface structures like depth to bedrock and soil properties as well as with respect to soil moisture/storage dynamics. Secondly, we will work out whether structurally similar hillslopes produce a similar event scale stream flow contribution, which of course is dependent on the degree of similarity of a) the rainfall forcing they receive and b) of their wetness state. To this end we will perform virtual experiments with the physically based model CATFLOW by perturbing behavioral model structures. These have been shown to portray system behavior and its architecture in a sense that they reproduce distributed observations of soil moisture and subsurface storm flow and represent the observed structural and textural signatures of soils, flow networks and vegetation.

Preferential flow in the vadose zone and interface dynamics: Impact of microbial exudates

NASA Astrophysics Data System (ADS)

Li, Biting; Pales, Ashley R.; Clifford, Heather M.; Kupis, Shyla; Hennessy, Sarah; Liang, Wei-Zhen; Moysey, Stephen; Powell, Brian; Finneran, Kevin T.; Darnault, Christophe J. G.

2018-03-01

In the hydrological cycle, the infiltration process is a critical component in the distribution of water into the soil and in the groundwater system. The nonlinear dynamics of the soil infiltration process yield preferential flow which affects the water distribution in soil. Preferential flow is influenced by the interactions between water, soil, plants, and microorganisms. Although the relationship among the plant roots, their rhizodeposits and water transport in soil has been the subject of extensive study, the effect of microbial exudates has been studied in only a few cases. Here the authors investigated the influence of two artificial microbial exudates-catechol and riboflavin-on the infiltration process, particularly unstable fingered flow, one form of preferential flow. Flow experiments investigating the effects of types and concentrations of microbial exudates on unstable fingered flow were conducted in a two-dimensional tank that was filled with ASTM

Development and application of kinetic model on biological anoxic/aerobic filter.

PubMed

Kim, Youngnoh; Tanaka, Kazuhiro; Lee, Yong-Woo; Chung, Jinwook

2008-01-01

An up-flow biological anoxic filter (BANF) has been developed to achieve high removal performance of suspended solids and BOD removal as well as nitrogen. With a view to understand treatment mechanisms, we developed a filtration model that incorporates filtration, deposit scoring and biological reactions simultaneously. The biological reactions consist of four types of reaction; dissolution of organic particles; utilization of dissolved organic matter; denitrification; and self-degradation of bacteria. Whereas the reactor is generally assumed to be a plug flow reactor in the filtration model, it is assumed a continuous-flow stirred tank reactor (CSTR) in the model of biological reactions. The hydrodynamics is supposed that the filter bottom (the portion sludge settled) is a CSTR and the filter bed (the portion filled with filter media) consists of number of CSTR of equal size arranged in series. The model obtained in this study was verified and simulated using experimental results taken from a pilot-scale plant and predicted the experimental data well, applying to design and operate BANF.

Using the nonlinear aquifer storage-discharge relationship to simulate the base flow of glacier- and snowmelt-dominated basins in northwest China

NASA Astrophysics Data System (ADS)

Gan, R.; Luo, Y.

2013-09-01

Base flow is an important component in hydrological modeling. This process is usually modeled by using the linear aquifer storage-discharge relation approach, although the outflow from groundwater aquifers is nonlinear. To identify the accuracy of base flow estimates in rivers dominated by snowmelt and/or glacier melt in arid and cold northwestern China, a nonlinear storage-discharge relationship for use in SWAT (Soil Water Assessment Tool) modeling was developed and applied to the Manas River basin in the Tian Shan Mountains. Linear reservoir models and a digital filter program were used for comparisons. Meanwhile, numerical analysis of recession curves from 78 river gauge stations revealed variation in the parameters of the nonlinear relationship. It was found that the nonlinear reservoir model can improve the streamflow simulation, especially for low-flow period. The higher Nash-Sutcliffe efficiency, logarithmic efficiency, and volumetric efficiency, and lower percent bias were obtained when compared to the one-linear reservoir approach. The parameter b of the aquifer storage-discharge function varied mostly between 0.0 and 0.1, which is much smaller than the suggested value of 0.5. The coefficient a of the function is related to catchment properties, primarily the basin and glacier areas.

Adapting HYDRUS-1D to Simulate Overland Flow and Reactive Transport During Sheet Flow Deviations

NASA Astrophysics Data System (ADS)

Liang, J.; Bradford, S. A.; Simunek, J.; Hartmann, A.

2017-12-01

The HYDRUS-1D code is a popular numerical model for solving the Richards equation for variably-saturated water flow and solute transport in porous media. This code was adapted to solve rather than the Richards equation for subsurface flow the diffusion wave equation for overland flow at the soil surface. The numerical results obtained by the new model produced an excellent agreement with the analytical solution of the kinematic wave equation. Model tests demonstrated its applicability to simulate the transport and fate of many different solutes, such as non-adsorbing tracers, nutrients, pesticides, and microbes. However, the diffusion wave or kinematic wave equations describe surface runoff as sheet flow with a uniform depth and velocity across the slope. In reality, overland water flow and transport processes are rarely uniform. Local soil topography, vegetation, and spatial soil heterogeneity control directions and magnitudes of water fluxes, and strongly influence runoff characteristics. There is increasing evidence that variations in soil surface characteristics influence the distribution of overland flow and transport of pollutants. These spatially varying surface characteristics are likely to generate non-equilibrium flow and transport processes. HYDRUS-1D includes a hierarchical series of models of increasing complexity to account for both physical equilibrium and non-equilibrium, e.g., dual-porosity and dual-permeability models, up to a dual-permeability model with immobile water. The same conceptualization as used for the subsurface was implemented to simulate non-equilibrium overland flow and transport at the soil surface. The developed model improves our ability to describe non-equilibrium overland flow and transport processes and to improves our understanding of factors that cause this behavior. The HYDRUS-1D overland flow and transport model was additionally also extended to simulate soil erosion. The HYDRUS-1D Soil Erosion Model has been verified by comparing with other soil erosion models. The model performed well when the average soil particle size is relatively large. The performance of the soil erosion model has been further validated by comparing with selected experimental datasets from the literature.

Red cabbage yield, heavy metal content, water use and soil chemical characteristics under wastewater irrigation.

PubMed

Tunc, Talip; Sahin, Ustun

2016-04-01

The objective of this 2-year field study was to evaluate the effects of drip irrigation with urban wastewaters reclaimed using primary (filtration) and secondary (filtration and aeration) processes on red cabbage growth and fresh yield, heavy metal content, water use and efficiency and soil chemical properties. Filtered wastewater (WW1), filtered and aerated wastewater (WW2), freshwater and filtered wastewater mix (1:1 by volume) (WW3) and freshwater (FW) were investigated as irrigation water treatments. Crop evapotranspiration decreased significantly, while water use efficiency increased under wastewater treatments compared to FW. WW1 treatment had the lowest value (474.2 mm), while FW treatments had the highest value (556.7 mm). The highest water use efficiency was found in the WW1 treatment as 8.41 kg m(-3), and there was a twofold increase with regard to the FW. Wastewater irrigation increased soil fertility and therefore red cabbage yield. WW2 treatment produced the highest total fresh yield (40.02 Mg ha(-1)). However, wastewater irrigation increased the heavy metal content in crops and soil. Cd content in red cabbage heads was above the safe limit, and WW1 treatment had the highest value (0.168 mg kg(-1)). WW3 treatment among wastewater treatments is less risky in terms of soil and crop heavy metal pollution and faecal coliform contamination. Therefore, WW3 wastewater irrigation for red cabbage could be recommended for higher yield and water efficiency with regard to freshwater irrigation.

Spatiotemporal variability of hydrologic soil properties and the implications for overland flow and land management in a peri-urban Mediterranean catchment

NASA Astrophysics Data System (ADS)

Ferreira, C. S. S.; Walsh, R. P. D.; Steenhuis, T. S.; Shakesby, R. A.; Nunes, J. P. N.; Coelho, C. O. A.; Ferreira, A. J. D.

2015-06-01

Planning of semi-urban developments is often hindered by a lack of knowledge on how changes in land-use affect catchment hydrological response. The temporal and spatial patterns of overland flow source areas and their connectivity in the landscape, particularly in a seasonal climate, remain comparatively poorly understood. This study investigates seasonal variations in factors influencing runoff response to rainfall in a peri-urban catchment in Portugal characterized by a mosaic of landscape units and a humid Mediterranean climate. Variations in surface soil moisture, hydrophobicity and infiltration capacity were measured in six different landscape units (defined by land-use on either sandstone or limestone) in nine monitoring campaigns at key times over a one-year period. Spatiotemporal patterns in overland flow mechanisms were found. Infiltration-excess overland flow was generated in rainfalls during the dry summer season in woodland on both sandstone and limestone and on agricultural soils on limestone due probably in large part to soil hydrophobicity. In wet periods, saturation overland flow occurred on urban and agricultural soils located in valley bottoms and on shallow soils upslope. Topography, water table rise and soil depth determined the location and extent of saturated areas. Overland flow generated in upslope source areas potentially can infiltrate in other landscape units downslope where infiltration capacity exceeds rainfall intensity. Hydrophilic urban and agricultural-sandstone soils were characterized by increased infiltration capacity during dry periods, while forest soils provided potential sinks for overland flow when hydrophilic in the winter wet season. Identifying the spatial and temporal variability of overland flow sources and sinks is an important step in understanding and modeling flow connectivity and catchment hydrologic response. Such information is important for land managers in order to improve urban planning to minimize flood risk.

Disposable and removable nucleic acid extraction and purification cartridges for automated flow-through systems

DOEpatents

Regan, John Frederick

2014-09-09

Removable cartridges are used on automated flow-through systems for the purpose of extracting and purifying genetic material from complex matrices. Different types of cartridges are paired with specific automated protocols to concentrate, extract, and purifying pathogenic or human genetic material. Their flow-through nature allows large quantities sample to be processed. Matrices may be filtered using size exclusion and/or affinity filters to concentrate the pathogen of interest. Lysed material is ultimately passed through a filter to remove the insoluble material before the soluble genetic material is delivered past a silica-like membrane that binds the genetic material, where it is washed, dried, and eluted. Cartridges are inserted into the housing areas of flow-through automated instruments, which are equipped with sensors to ensure proper placement and usage of the cartridges. Properly inserted cartridges create fluid- and air-tight seals with the flow lines of an automated instrument.

Examining diel patterns of soil and xylem moisture using electrical resistivity imaging

NASA Astrophysics Data System (ADS)

Mares, Rachel; Barnard, Holly R.; Mao, Deqiang; Revil, André; Singha, Kamini

2016-05-01

The feedbacks among forest transpiration, soil moisture, and subsurface flowpaths are poorly understood. We investigate how soil moisture is affected by daily transpiration using time-lapse electrical resistivity imaging (ERI) on a highly instrumented ponderosa pine and the surrounding soil throughout the growing season. By comparing sap flow measurements to the ERI data, we find that periods of high sap flow within the diel cycle are aligned with decreases in ground electrical conductivity and soil moisture due to drying of the soil during moisture uptake. As sap flow decreases during the night, the ground conductivity increases as the soil moisture is replenished. The mean and variance of the ground conductivity decreases into the summer dry season, indicating drier soil and smaller diel fluctuations in soil moisture as the summer progresses. Sap flow did not significantly decrease through the summer suggesting use of a water source deeper than 60 cm to maintain transpiration during times of shallow soil moisture depletion. ERI captured spatiotemporal variability of soil moisture on daily and seasonal timescales. ERI data on the tree showed a diel cycle of conductivity, interpreted as changes in water content due to transpiration, but changes in sap flow throughout the season could not be interpreted from ERI inversions alone due to daily temperature changes.

Mechanisms of thorium migration in a semiarid soil.

PubMed

Bednar, A J; Gent, D B; Gilmore, J R; Sturgis, T C; Larson, S L

2004-01-01

Thorium concentrations at Kirtland Air Force Base training sites in Albuquerque, NM, have been previously described; however, the mechanisms of thorium migration were not fully understood. This work describes the processes affecting thorium mobility in this semiarid soil, which has implications for future remedial action. Aqueous extraction and filtration experiments have demonstrated the colloidal nature of thorium in the soil, due in part to the low solubility of thorium oxide. Colloidal material was defined as that removed by a 0.22-microm or smaller filter after being filtered to nominally dissolved size (0.45 microm). Additionally, association of thorium with natural organic matter is suggested by micro- and ultrafiltration methods, and electrokinetic data, which indicate thorium migration as a negatively charged particle or anionic complex with organic matter. Soil fractionation and digestion experiments show a bimodal distribution of thorium in the largest and smallest size fractions, most likely associated with detrital plant material and inorganic oxide particles, respectively. Plant uptake studies suggest this could also be a mode of thorium migration as plants grown in thorium-containing soil had a higher thorium concentration than those in control soils. Soil erosion laboratory experiments with wind and surface water overflow were performed to determine bulk soil material movement as a possible mechanism of mobility. Information from these experiments is being used to determine viable soil stabilization techniques at the site to maintain a usable training facility with minimal environmental impact.

Device for separating CO2 from fossil-fueled power plant emissions

DOEpatents

Burchell, Timothy D [Oak Ridge, TN; Judkins, Roddie R [Knoxville, TN; Wilson, Kirk A [Knoxville, TN

2002-04-23

A gas separation device includes an inner conduit, and a concentric outer conduit. An electrically conductive filter media, preferably a carbon fiber composite molecular sieve, is provided in the annular space between the inner conduit and the outer conduit. Gas flows through the inner conduit and the annular space between the inner conduit and the outer conduit, so as to contact the filter media. The filter media preferentially adsorbs at least one constituent of the gas stream. The filter media is regenerated by causing an electric current to flow through the filter media. The inner conduit and outer conduit are preferably electrically conductive whereby the regeneration of the filter media can be electrically stimulated. The invention is particularly useful for the removal of CO.sub.2 from the exhaust gases of fossil-fueled power plants.

Disk filter

DOEpatents

Bergman, Werner

1986-01-01

An electric disk filter provides a high efficiency at high temperature. A hollow outer filter of fibrous stainless steel forms the ground electrode. A refractory filter material is placed between the outer electrode and the inner electrically isolated high voltage electrode. Air flows through the outer filter surfaces through the electrified refractory filter media and between the high voltage electrodes and is removed from a space in the high voltage electrode.

Disk filter

DOEpatents

Bergman, W.

1985-01-09

An electric disk filter provides a high efficiency at high temperature. A hollow outer filter of fibrous stainless steel forms the ground electrode. A refractory filter material is placed between the outer electrode and the inner electrically isolated high voltage electrode. Air flows through the outer filter surfaces through the electrified refractory filter media and between the high voltage electrodes and is removed from a space in the high voltage electrode.

On pads and filters: Processing strong-motion data

USGS Publications Warehouse

Boore, D.M.

2005-01-01

Processing of strong-motion data in many cases can be as straightforward as filtering the acceleration time series and integrating to obtain velocity and displacement. To avoid the introduction of spurious low-frequency noise in quantities derived from the filtered accelerations, however, care must be taken to append zero pads of adequate length to the beginning and end of the segment of recorded data. These padded sections of the filtered acceleration need to be retained when deriving velocities, displacements, Fourier spectra, and response spectra. In addition, these padded and filtered sections should also be included in the time series used in the dynamic analysis of structures and soils to ensure compatibility with the filtered accelerations.

Design parameters for rotating cylindrical filtration

NASA Technical Reports Server (NTRS)

Schwille, John A.; Mitra, Deepanjan; Lueptow, Richard M.

2002-01-01

Rotating cylindrical filtration displays significantly reduced plugging of filter pores and build-up of a cake layer, but the number and range of parameters that can be adjusted complicates the design of these devices. Twelve individual parameters were investigated experimentally by measuring the build-up of particles on the rotating cylindrical filter after a fixed time of operation. The build-up of particles on the filter depends on the rotational speed, the radial filtrate flow, the particle size and the gap width. Other parameters, such as suspension concentration and total flow rate are less important. Of the four mechanisms present in rotating filters to reduce pore plugging and cake build-up, axial shear, rotational shear, centrifugal sedimentation and vortical motion, the evidence suggests rotational shear is the dominant mechanism, although the other mechanisms still play minor roles. The ratio of the shear force acting parallel to the filter surface on a particle to the Stokes drag acting normal to the filter surface on the particle due to the difference between particle motion and filtrate flow can be used as a non-dimensional parameter that predicts the degree of particle build-up on the filter surface for a wide variety of filtration conditions. c2002 Elsevier Science B.V. All rights reserved.

Identifying Dust Sources by Positive Matrix Factorization (PMF)

NASA Astrophysics Data System (ADS)

Engelbrecht, Johann P.

2010-05-01

This presentation is on the source attribution by Positive Matrix Factorization (PMF) of aerosol samples collected in Iraq, a major source of mineral dust in the Middle East. Globally transported mineral dust from North Africa, the Middle East, China, and elsewhere are routinely being sampled at high elevation monitoring sites such as those on the Canary Islands and Hawaii, and many ambient monitoring sites worldwide. Chemical results of these filter samples reflect differences in sources impacting at each site, further complicated by the regional geomorphology and meteorology. Trace elements, isotopes, elemental ratios, and mineralogy are generally being used to pinpoint geological source regions of natural and anthropogenic dusts. A receptor site is seldom impacted by only one source at a time. Dust palls are continually being modified by added dust from soils across which they migrate, also by particle segregation in the dust plume, and precipitation of the coarser particles. The result is that dust is a mixture, with contributions from different sources, each with a different chemical and mineralogical signature. PMF is a non-negative factorization procedure that produces only positive factor scores and loadings, in contrast to classical factor analysis (FA) and Principal Components Analysis (PCA). PMF enables us to resolve factors (chemical signatures) for source types contributing to the ambient chemical data set, and also models the source-type contributions to individual ambient samples. The latter can often be related to specific source regions. PMF was applied separately to two ambient data sets collected in Iraq in 2006, the one on Teflon membrane filters and the other on quartz fiber. Each of the filter types were previously analyzed for different chemical species: Teflon membrane for elements, by XRF and ICP-MS, while quartz fiber filters were analyzed for ions and carbon. [Engelbrecht et al. 2009] A set of 392 Teflon filter samples analyzed for 25 elemental species was modeled by PMF. A five factor solution identified three soil factors, a silicate soil, limestone soil, and a gypsum soil, as well as a salt factor and an anthropogenic metal factor. Similarly, a set of 362 quartz filter samples analyzed for 10 selected chemical species was modeled by PMF. A five factor solution provided a limestone-gypsum soil, diesel combustion, secondary ammonium sulfate, salt and agricultural-burnpit combustion source type. Examples of time series plots of PMF factor contributions for each of six sampling sites (Balad, Baghdad, Tallil, Tikrit, Taji, and Al Asad) will be discussed. Engelbrecht , J. P., McDonald, E. V., Gillies, J. A., Jayanty, R. K. M., Casuccio, G., and Gertler, A. W., 2009, Characterizing mineral dusts and other aerosols from the Middle East - Part 1: Ambient sampling: Inhalation Toxicology, v. 21, p. 297-326.

Phosphorus exchangeability and leaching losses from two grassland soils.

PubMed

Sinaj, S; Stamm, C; Toor, G S; Condron, L M; Hendry, T; Di, H J; Cameron, K C; Frossard, E

2002-01-01

Although phosphate phosphorus (P) is strongly sorbed in many soils, it may be quickly transported through the soil by preferential flow. Under flood irrigation, preferential flow is especially pronounced and associated solute losses may be important. Phosphorus losses induced by flood irrigation were investigated in a lysimeter study. Detailed soil chemical analyses revealed that P was very mobile in the topsoil, but the higher P-fixing capacity of the subsoil appeared to restrict P mobility. Application of a dye tracer enabled preferential flow pathways to be identified. Soil sampling according to dye staining patterns revealed that exchangeable P was significantly greater in preferential flow areas as compared with the unstained soil matrix. This could be partly attributed to the accumulation of organic carbon and P, together with enhanced leaching of Al- and Fe-oxides in the preferential flow areas, which resulted in reduced P sorption. The irrigation water caused a rapid hydrologic response by displacement of resident water from the subsoil. Despite the occurrence of preferential flow, most of the outflowing water was resident soil water and very low in P. In these soils the occurrence of preferential flow per se is not sufficient to cause large P losses even if the topsoil is rich in P. It appears that the P was retained in lower parts of the soil profile characterized by a very high P-fixing capacity. This study demonstrates the risks associated with assessing potential P losses on the basis of P mobility in the topsoil alone.

Control of the spread of inorganic elements by shelterbelt in agricultural landscape

NASA Astrophysics Data System (ADS)

Życzyńska-Bałoniak, Irena; Wojciech Szajdak, Lech

2010-05-01

Non-point pollution from agricultural lands involves primarily three transport processes: runoff, leaching, and erosion-sedimentation. The primary transport medium for all three processes is water, which is also a significant carrier of nutrients and sediments. Hydrologic processes important relative to non-point pollution are: (a) infiltration, (b) subsurface flow, (c) overland flow. A better understanding of the impact of shelterbelt on the decrease the quantities of chemical compounds in ground water should increase our ability to predict the improvement of the quality of ground water. The objective of this study was to evaluate the effect of shelterbelt on the decrease of calcium, magnesium and inorganic carbon in ground water passing through the shelterbelt from adjoining cultivated fields. The investigations were carried out in Turew in Chlapowski's Agroecological Park situated 40 km South-West of Poznań (West Polish Lowland). Afforestations represent well developed network of shelterbelts (mid-field rows of trees afforestation). The established network of shelterbelts in Turew is the unique in Europe. Ground water under cultivated field and shelterbelt from the artificial wells ones a month during 7 years from 2000 to 2006 was sampled and investigated. Ground water under shelterbelt flows away from adjoining cultivated field and passing through the shelterbelt. The first distance of this shelterbelt 104 m long is located on mineral soils (division-autogenic soils, order-brown forest soils, type-hapludalfs, subtype-glossudalfs) next from 104 to 125 m on mineral organic soils (division-hydrogenic soils, order-post-bog, soils, type-mucky soils, subtype-muckous). Calcium, magnesium and mineral carbon quantities have been investigated in the ground water of shelterbelts. The direction of water flow was estimated on the basis of the water level in the wells. Shelterbelt includes different species with the dominations of the maple, ash, beech, and hawthorn. Ground water samples were taken from the wells located (a) in the border between adjoining cultivated fields and shelterbelts, and (b) in the distances 62 m, 104 m and 125 m from the edge of the shelterbelt. The concentrations of calciumand magnesium and also mineral carbon were studied by examining ground water filtered by the filter paper Whatman GT/C. The concentrations of calcium and magnesium were investigated by the method by Hermanowicz. Dry masses were isolated by the freeze-dried and drying to the constant of weight at 105oC. Total organic carbon, dissolved organic carbon and mineral carbon were measured on Total Organic Carbon Analyzer 5050A, ASI 5000A auto sampler, SSM - 5000A solid sample module, (Shimadzu, Japan). Total amount of yearly rainfall was in 2000 - 671 mm, 2001 - 544 mm, 2002 - 495 mm, 2003 - 449 mm, 2004 - 672 mm, 2005 - 551 mm, 2006 - 578 mm. Mean temperatures ranged from 9.2 to 13.3oC. The highest temperature +23.5oC was measured in July 2000, and the lowest -6.4oC observed in January 2006. The precision based on replicate analyses, were ± 4% for Ca+2, ± 3% for Mg+2, ± 4% for dry mass. All the determinations were run in triplicate, and the results were averaged. The differences among the concentrations of calcium, magnesium and mineral carbon were attributed solely of width of the shelterbelt. Shelterbelt revealed the improvement in the quality of ground water. Concerns over the environmental impacts of the elements of agricultural landscapes have focused attention on the study of calcium, magnesium, mineral carbon in ground water. These investigations have shown high contents of chemical compounds migrates ground water from cultivated fields. Ground water under cultivated field revealed high concentrations of calcium, which yearly mean contents are equaled from 81.9 to 179.2 mg/l. It was proved that biogeochemical barrier such as shelterbelt efficiency decrease the quantity of chemical compounds in ground water. The highest decrease of determined forms in the first distance of shelterbelt (62 m) and ranged for calcium from 26 to 34%, magnesium to 26% and mineral carbon to 71% was observed. On the basis of all aspects it seems that the first distance 62 m of shelterbelt is the most efficient for the function as biogeochemical barrier.

Soil amendments for heavy metals removal from stormwater runoff discharging to environmentally sensitive areas

NASA Astrophysics Data System (ADS)

Trenouth, William R.; Gharabaghi, Bahram

2015-10-01

Concentrations of dissolved metals in stormwater runoff from urbanized watersheds are much higher than established guidelines for the protection of aquatic life. Five potential soil amendment materials derived from affordable, abundant sources have been tested as filter media using shaker tests and were found to remove dissolved metals in stormwater runoff. Blast furnace (BF) slag and basic oxygenated furnace (BOF) slag from a steel mill, a drinking water treatment residual (DWTR) from a surface water treatment plant, goethite-rich overburden (IRON) from a coal mine, and woodchips (WC) were tested. The IRON and BOF amendments were shown to remove 46-98% of dissolved metals (Cr, Co, Cu, Pb, Ni, Zn) in repacked soil columns. Freundlich adsorption isotherm constants for six metals across five materials were calculated. Breakthrough curves of dissolved metals and total metal accumulation within the filter media were measured in column tests using synthetic runoff. A reduction in system performance over time occurred due to progressive saturation of the treatment media. Despite this, the top 7 cm of each filter media removed up to 72% of the dissolved metals. A calibrated HYDRUS-1D model was used to simulate long-term metal accumulation in the filter media, and model results suggest that for these metals a BOF filter media thickness as low as 15 cm can be used to improve stormwater quality to meet standards for up to twenty years. The treatment media evaluated in this research can be used to improve urban stormwater runoff discharging to environmentally sensitive areas (ESAs).

Time-domain representation of frequency-dependent foundation impedance functions

USGS Publications Warehouse

Safak, E.

2006-01-01

Foundation impedance functions provide a simple means to account for soil-structure interaction (SSI) when studying seismic response of structures. Impedance functions represent the dynamic stiffness of the soil media surrounding the foundation. The fact that impedance functions are frequency dependent makes it difficult to incorporate SSI in standard time-history analysis software. This paper introduces a simple method to convert frequency-dependent impedance functions into time-domain filters. The method is based on the least-squares approximation of impedance functions by ratios of two complex polynomials. Such ratios are equivalent, in the time-domain, to discrete-time recursive filters, which are simple finite-difference equations giving the relationship between foundation forces and displacements. These filters can easily be incorporated into standard time-history analysis programs. Three examples are presented to show the applications of the method.

The importance of temporal inequality in quantifying vegetated filter strip removal efficiencies

NASA Astrophysics Data System (ADS)

Gall, H. E.; Schultz, D.; Mejia, A.; Harman, C. J.; Raj, C.; Goslee, S.; Veith, T.; Patterson, P. H.

2017-12-01

Vegetated filter strips (VFSs) are best management practices (BMPs) commonly implemented adjacent to row-cropped fields to trap overland transport of sediment and other constituents often present in agricultural runoff. VFSs are generally reported to have high sediment removal efficiencies (i.e., 70 - 95%); however, these values are typically calculated as an average of removal efficiencies observed or simulated for individual events. We argue that due to: (i) positively correlated sediment concentration-discharge relationships; (ii) strong temporal inequality exhibited by sediment transport; and (iii) decreasing VFS performance with increasing flow rates, VFS removal efficiencies over annual time scales may be significantly lower than the per-event values or averages typically reported in the literature and used in decision-making models. By applying a stochastic approach to a two-component VFS model, we investigated the extent of the disparity between two calculation methods: averaging efficiencies from each event over the course of one year, versus reporting the total annual load reduction. We examined the effects of soil texture, concentration-discharge relationship, and VFS slope to reveal the potential errors that may be incurred by ignoring the effects of temporal inequality in quantifying VFS performance. Simulation results suggest that errors can be as low as < 2% and as high as > 20%, with the differences between the two methods of removal efficiency calculations greatest for: (i) soils with high percentage of fine particulates; (ii) VFSs with higher slopes; and (iii) strongly positive concentration-discharge relationships. These results can aid in annual-scale decision making for achieving downstream water quality goals.

Enhancement of flow measurements using fluid-dynamic constraints

NASA Astrophysics Data System (ADS)

Egger, H.; Seitz, T.; Tropea, C.

2017-09-01

Novel experimental modalities acquire spatially resolved velocity measurements for steady state and transient flows which are of interest for engineering and biological applications. One of the drawbacks of such high resolution velocity data is their susceptibility to measurement errors. In this paper, we propose a novel filtering strategy that allows enhancement of the noisy measurements to obtain reconstruction of smooth divergence free velocity and corresponding pressure fields which together approximately comply to a prescribed flow model. The main step in our approach consists of the appropriate use of the velocity measurements in the design of a linearized flow model which can be shown to be well-posed and consistent with the true velocity and pressure fields up to measurement and modeling errors. The reconstruction procedure is then formulated as an optimal control problem for this linearized flow model. The resulting filter has analyzable smoothing and approximation properties. We briefly discuss the discretization of the approach by finite element methods and comment on the efficient solution by iterative methods. The capability of the proposed filter to significantly reduce data noise is demonstrated by numerical tests including the application to experimental data. In addition, we compare with other methods like smoothing and solenoidal filtering.

Process and apparatus for analyzing specimens for the presence of microorganisms therein

NASA Technical Reports Server (NTRS)

Vannest, Richard D. (Inventor); Meyer, Michael C. (Inventor); Gibson, Sandra F. (Inventor); Keyser, George F. (Inventor); Jones, Paul W. (Inventor); Aldridge, Jr., Clifton (Inventor); Holen, James T. (Inventor)

1980-01-01

Microorganisms in a specimen are detected, identified, and enumerated by introducing the specimen into a sampling cartridge and diluting the specimen with a known volume of water within the cartridge. The cartridge has a manifold and several cassettes attached to the manifold. Each cassette contains a serpentine flow channel having a series of filters therein and a detection cell located downstream from each filter. The flow channel in each cassette also contains a culture medium which is freeze dried and is highly selective in the sense that it promotes the growth of one type of microorganism, but not others. The mixture of the specimen and water flows from the manifold into the flow channel of each cassette where it rehydrates the culture medium therein and further flows through the filters. Each filter removes a known proportion of the microorganisms from the mixture of specimen, water and medium, thereby effecting a serial dilution. After the cassettes are heated to incubate the microoganisms, the detection cells are observed for growth of the microorganisms therein which is manifested in a change in the light transmitting characteristics of the mixtures within the cells.

Modeling preferential water flow and solute transport in unsaturated soil using the active region model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sheng, F.; Wang, K.; Zhang, R.

2009-03-15

Preferential flow and solute transport are common processes in the unsaturated soil, in which distributions of soil water content and solute concentrations are often characterized as fractal patterns. An active region model (ARM) was recently proposed to describe the preferential flow and transport patterns. In this study, ARM governing equations were derived to model the preferential soil water flow and solute transport processes. To evaluate the ARM equations, dye infiltration experiments were conducted, in which distributions of soil water content and Cl{sup -} concentration were measured. Predicted results using the ARM and the mobile-immobile region model (MIM) were compared withmore » the measured distributions of soil water content and Cl{sup -} concentration. Although both the ARM and the MIM are two-region models, they are fundamental different in terms of treatments of the flow region. The models were evaluated based on the modeling efficiency (ME). The MIM provided relatively poor prediction results of the preferential flow and transport with negative ME values or positive ME values less than 0.4. On the contrary, predicted distributions of soil water content and Cl- concentration using the ARM agreed reasonably well with the experimental data with ME values higher than 0.8. The results indicated that the ARM successfully captured the macroscopic behavior of preferential flow and solute transport in the unsaturated soil.« less

Flow analysis system and method

NASA Technical Reports Server (NTRS)

Hill, Wayne S. (Inventor); Barck, Bruce N. (Inventor)

1998-01-01

A non-invasive flow analysis system and method wherein a sensor, such as an acoustic sensor, is coupled to a conduit for transmitting a signal which varies depending on the characteristics of the flow in the conduit. The signal is amplified and there is a filter, responsive to the sensor signal, and tuned to pass a narrow band of frequencies proximate the resonant frequency of the sensor. A demodulator generates an amplitude envelope of the filtered signal and a number of flow indicator quantities are calculated based on variations in amplitude of the amplitude envelope. A neural network, or its equivalent, is then used to determine the flow rate of the flow in the conduit based on the flow indicator quantities.

Finding a Needle in a PCAP

DTIC Science & Technology

2015-01-27

Separate from analysis Indexing: • Timestamp Files • BPF Filters • GUI tools • Splunk 5 YAF PCAP Features Rolling PCAP dump • Rotates files using time...PCAP file for each flow. • Use with BPF filters. 6 Gh0st Rat Investigation 7 Gh0st Chinese remote access Trojan Free source code Easy to modify...Merge PCAP files w/ mergecap PCAP Write a BPF filter that will return session Separate Flows TCPDUMP YAF 26 Questions? CERT NetSA tools website

Development of Test Protocols for International Space Station Particulate Filters

NASA Technical Reports Server (NTRS)

Vijayakumar, R.; Green, Robert D.; Agui, Juan H.

2015-01-01

Air quality control on the International Space Station (ISS) is a vital requirement for maintaining a clean environment for the crew and the hardware. This becomes a serious challenge in pressurized space compartments since no outside air ventilation is possible, and a larger particulate load is imposed on the filtration system due to lack of gravitational settling. The ISS Environmental Control and Life Support System (ECLSS) uses a filtration system that has been in use for over 14 years and has proven to meet this challenge. The heart of this system is a traditional High-Efficiency Particulate Air (HEPA) filter configured to interface with the rest of the life support elements and provide effective cabin filtration. The filter element for this system has a non-standard cross-section with a length-to-width ratio (LW) of 6.6. A filter test setup was designed and built to meet industry testing standards. A CFD analysis was performed to initially determine the optimal duct geometry and flow configuration. Both a screen and flow straighter were added to the test duct design to improve flow uniformity and face velocity profiles were subsequently measured to confirm. Flow quality and aerosol mixing assessments show that the duct flow is satisfactory for the intended leak testing. Preliminary leak testing was performed on two different ISS filters, one with known perforations and one with limited use, and results confirmed that the testing methods and photometer instrument are sensitive enough to detect and locate compromised sections of an ISS BFE.Given the engineering constraints in designing spacecraft life support systems, it is anticipated that non-industry standard filters will be required in future designs. This work is focused on developing test protocols for testing the ISS BFE filters, but the methodology is general enough to be extended to other present and future spacecraft filters. These techniques for characterizing the test duct and perform leak testing can be applied to conducting acceptance testing and inventory testing for future manned exploration programs with air revitalization filtration needs, possibly even for in-situ filter element integrity testing for extensively long-duration missions. We plan to address the unique needs for test protocols for crewed spacecraft particulate filters by preparing the initial version of a standard, to be documented as a NASA Technical Memorandum (TM).

Andic soil features and debris flows in Italy. New perspective towards prediction

NASA Astrophysics Data System (ADS)

Scognamiglio, Solange; Calcaterra, Domenico; Iamarino, Michela; Langella, Giuliano; Orefice, Nadia; Vingiani, Simona; Terribile, Fabio

2016-04-01

Debris flows are dangerous hazards causing fatalities and damage. Previous works have demonstrated that the materials involved by debris flows in Campania (southern Italy) are soils classified as Andosols. These soils have peculiar chemical and physical properties which make them fertile but also vulnerable to landslide. In Italy, andic soil properties are found both in volcanic and non-volcanic mountain ecosystems (VME and NVME). Here, we focused on the assessment of the main chemical and physical properties of the soils in the detachment areas of eight debris flows occurred in NVME of Italy in the last 70 years. Such landslides were selected by consulting the official Italian geodatabase (IFFI Project). Andic properties (by means of ammonium oxalate extractable Fe, Si and Al forms for the calculation of Alo+1/2Feo) were also evaluated and a comparison with soils of VME was performed to assess possible common features. Landslide source areas were characterised by slope gradient ranging from 25° to 50° and lithological heterogeneity of the bedrock. The soils showed similar, i.e. all were very deep, had a moderately thick topsoil with a high organic carbon (OC) content decreasing regularly with depth. The cation exchange capacity trend was generally consistent with the OC and the pH varied from extremely to slightly acid, but increased with depth. Furthermore, the soils had high water retention values both at saturation (0.63 to 0.78 cm3 cm-3) and in the dryer part of the water retention curve, and displayed a prevalent loamy texture. Such properties denote the chemical and physical fertility of the investigated ecosystems. The values of Alo+1/2Feoindicated that the soils had vitric or andic features and can be classified as Andosols. The comparison between NVME soils and those of VME showed similar depth, thickness of soil horizons, and family texture, whereas soil pH, degree of development of andic properties and allophane content were higher for VME soils. Such results are consistent with the different soil environments; indeed, in VME a continuous soil enrichment of weatherable volcanic glass affects both soil pH and formation of short range order clay minerals. In conclusion, the direct relationship between debris flows and Andosols, previously found in the Campania VME, is confirmed in some NVME. These findings highlight the similarity of the materials involved by debris flows both in VME and NVME and suggest the existence of a pedological control on debris flow initiation. Furthermore, these results encourage a further extension of soil studies to other European mountain ecosystems. The evidence that andic soils may play a crucial role in debris flows initiation in Italy enables to develop a new strategy for debris flows forecasting. For the case of Sarno 1998 landslides, we provide an example of innovative approach exploring the results obtained by combining the spatial distribution of these andic soils with "on the fly" simulation modelling of the soil water balance, using real time weather forecasting data. The obtained results enable to develop promising Geospatial Decision Support Systems to improve our ability to predict debris flows on soil-covered slopes.

40 CFR 1065.1107 - Sample media and sample system preparation; sample system assembly.

Code of Federal Regulations, 2014 CFR

2014-07-01

...) For capturing PM, we recommend using pure quartz filters with no binder. Select the filter diameter to minimize filter change intervals, accounting for the expected PM emission rate, sample flow rate, and... filter without replacing the sorbent or otherwise disassembling the batch sampler. In those cases...

14 CFR 33.71 - Lubrication system.

Code of Federal Regulations, 2012 CFR

2012-01-01

... in which an aircraft is expected to operate. (b) Oil strainer or filter. There must be an oil strainer or filter through which all of the engine oil flows. In addition: (1) Each strainer or filter... normal rate through the rest of the system with the strainer or filter element completely blocked. (2...

Unstable Pore-Water Flow in Intertidal Wetlands

NASA Astrophysics Data System (ADS)

Barry, D. A.; Shen, C.; Li, L.

2014-12-01

Salt marshes are important intertidal wetlands strongly influenced by interactions between surface water and groundwater. Bordered by coastal water, the marsh system undergoes cycles of inundation and exposure driven by the tide. This leads to dynamic, complex pore-water flow and solute transport in the marsh soil. Pore-water circulations occur over vastly different spatial and temporal scales with strong link to the marsh topography. These circulations control solute transport between the marsh soil and the tidal creek, and ultimately affect the overall nutrient exchange between the marsh and coastal water. The pore-water flows also dictate the soil condition, particularly aeration, which influences the marsh plant growth. Numerous studies have been carried out to examine the pore-water flow process in the marsh soil driven by tides, focusing on stable flow with the assumption of homogeneity in soil and fluid properties. This assumption, however, is questionable given the actual inhomogeneous conditions in the field. For example, the salinity of surface water in the tidal creek varies temporally and spatially due to the influence of rainfall and evapotranspiration as well as the freshwater input from upland areas to the estuary, creating density gradients across the marsh surface and within the marsh soil. Many marshes possess soil stratigraphy with low-permeability mud typically overlying high-permeability sandy deposits. Macropores such as crab burrows are commonly distributed in salt marsh sediments. All these conditions are prone to the development of non-uniform, unstable preferential pore-water flow in the marsh soil, for example, funnelling and fingering. Here we present results from laboratory experiments and numerical simulations to explore such unstable flow. In particular, the analysis aims to address how the unstable flow modifies patterns of local pore-water movement and solute transport, as well as the overall exchange between the marsh soil and creek water. The changes would influence not only the marsh soil condition for plant growth but also nutrient cycling in the marsh soil and discharge to the coastal sea.

Benchmarking a Soil Moisture Data Assimilation System for Agricultural Drought Monitoring

NASA Technical Reports Server (NTRS)

Hun, Eunjin; Crow, Wade T.; Holmes, Thomas; Bolten, John

2014-01-01

Despite considerable interest in the application of land surface data assimilation systems (LDAS) for agricultural drought applications, relatively little is known about the large-scale performance of such systems and, thus, the optimal methodological approach for implementing them. To address this need, this paper evaluates an LDAS for agricultural drought monitoring by benchmarking individual components of the system (i.e., a satellite soil moisture retrieval algorithm, a soil water balance model and a sequential data assimilation filter) against a series of linear models which perform the same function (i.e., have the same basic inputoutput structure) as the full system component. Benchmarking is based on the calculation of the lagged rank cross-correlation between the normalized difference vegetation index (NDVI) and soil moisture estimates acquired for various components of the system. Lagged soil moistureNDVI correlations obtained using individual LDAS components versus their linear analogs reveal the degree to which non-linearities andor complexities contained within each component actually contribute to the performance of the LDAS system as a whole. Here, a particular system based on surface soil moisture retrievals from the Land Parameter Retrieval Model (LPRM), a two-layer Palmer soil water balance model and an Ensemble Kalman filter (EnKF) is benchmarked. Results suggest significant room for improvement in each component of the system.

Soil amendment using poplar woodchips to enhance the treatment of wastewater-originated nutrients.

PubMed

Meffe, Raffaella; de Miguel, Ángel; Martínez Hernández, Virtudes; Lillo, Javier; de Bustamante, Irene

2016-09-15

Vegetation filters, a nature based wastewater regeneration technology, have been reported as a feasible solution for small municipalities and scattered populations with limited access to sewage networks. However even when such a treatment is properly planned, the leaching of contaminants through the unsaturated zone may occur. The amendment of soil with a readily-labile source of carbon is supposed to ameliorate the removal of contaminants by stimulating microbial activity and enhancing sorption processes. In this study, lab-scale leaching column experiments were carried out to explore if the addition of woodchips to the soil could be a feasible strategy to be integrated in a vegetation filter. Two different types of arrangement of soil and woodchips layers were tested. The soil was collected from an operating vegetation filter treating wastewater of an office building characterised by a high nutrient load. Daily pulse of synthetic wastewater were applied into the columns and effluent samples were collected and analyzed for major ions, total nitrogen (NT), total phosphorous (PT) and chemical oxygen demand (COD). By the end of the experiment, NT, NO3-N and PT soil contents were also measured. Results indicate that amendments with woodchips enhance the elimination of wastewater-originated contaminants. NT removal in the columns with woodchips reaches a value of 99.4%. The main processes responsible for this elimination are NH4-N sorption and nitrification/denitrification. This latter fostered by the reduced redox conditions due to the enhanced microbial activity. High removal of PT (99%) is achieved independently of the woodchips presence due to retention and/or precipitation phenomena. The COD removal efficiency is not affected by the presence of the woodchips. The leaching of organic carbon occurs only during the experimental start-up period. Copyright © 2016 Elsevier Ltd. All rights reserved.

Application of a Transient Storage Zone Model o Soil Pipeflow Tracer Injection Experiments

USDA-ARS?s Scientific Manuscript database

Soil pipes, defined here as discrete preferential flow paths generally parallel to the slope, are important subsurface flow pathways that play a role in many soil erosion phenomena. However, limited research has been performed on quantifying and characterizing their flow and transport characteristic...

Study of the Effect of Turbulence and Large Obstacles on the Evaporation from Bare Soil Surface through Coupled Free-flow and Porous-medium Flow Model

NASA Astrophysics Data System (ADS)

Gao, B.; Smits, K. M.

2017-12-01

Evaporation is a strongly coupled exchange process of mass, momentum and energy between the atmosphere and the soil. Several mechanisms influence evaporation, such as the atmospheric conditions, the structure of the soil surface, and the physical properties of the soil. Among the previous studies associated with evaporation modeling, most efforts use uncoupled models which simplify the influences of the atmosphere and soil through the use of resistance terms. Those that do consider the coupling between the free flow and porous media flow mainly consider flat terrain with grain-scale roughness. However, larger obstacles, which may form drags or ridges allowing normal convective air flow through the soil, are common in nature and may affect the evaporation significantly. Therefore, the goal of this work is to study the influence of large obstacles such as wavy surfaces on the flow behavior within the soil and exchange processes to the atmosphere under turbulent free-flow conditions. For simplicity, the soil surface with large obstacles are represented by a simple wavy surface. To do this, we modified a previously developed theory for two-phase two-component porous-medium flow, coupling it to single-phase two-component turbulent flow to simulate and analyze the evaporation from wavy soil surfaces. Detailed laboratory scale experiments using a wind tunnel interfaced with a porous media tank were carried out to test the modeling results. The characteristics of turbulent flow across a permeable wavy surface are discussed. Results demonstrate that there is an obvious recirculation zone formed at the surface, which is special because of the accumulation of water vapor and the thicker boundary layer in this area. In addition, the influences of both the free flow and porous medium on the evaporation are also analyzed. The porous medium affects the evaporation through the amount of water it can provide to the soil surface; while the atmosphere influences the evaporation through the gradients formed within the boundary layer. This study gives a primary cognition on the evaporation from bare soil surface with obstacles. Ongoing work will include a deep understanding of the mechanisms which may provide the basis for land-atmosphere study on field scale.

The mobilization of aluminum in a natural soil system: Effects of hydrologic pathways

USGS Publications Warehouse

Cozzarelli, Isabelle M.; Herman, Janet S.; Parnell, Roderic A.

1987-01-01

A two-component soil water flow model was used in conjunction with an equilibrium speciation model WATEQF to study aluminum mobility in soils of a forested watershed, White Oak Run, in the Shenandoah National Park, Virginia. Soil solution samples, taken from the O, E, B, C1, and C2horizons, were collected from zero-tension lysimeters designed to collect faster gravitational macropore flow and tension lysimeters designed to collect slower capillary micropore flow. Dissolved aluminum was fractionated into acid-soluble, inorganic monomeric, and organic monomeric aluminum. Soil water aluminum concentrations decreased with depth indicating that the deep soil is a sink for aluminum. All waters contained significant concentrations of acid-soluble aluminum and exhibited a negative correlation between pH and the inorganic monomeric aluminum concentrations. Water in the shallow soil showed distinctly different chemical compositions for the two flow types, while C horizon micropore and macropore waters were more similar. Because of its shorter residence time, water flowing in deep soil macropores underwent less extensive neutralization and immobilization of aqueous aluminum than micropore water. The O horizon macropore waters were undersaturated for all hydroxide, silicate, and sulfate mineral phases considered. The C horizon samples from both flow types were near equilibrium with respect to kaolinite and synthetic gibbsite, indicating that mineral solubility controls water chemistry in the deep soil, while organic substances are the key control in the shallow macropore waters.

The impact of non-isothermal soil moisture transport on evaporation fluxes in a maize cropland

NASA Astrophysics Data System (ADS)

Shao, Wei; Coenders-Gerrits, Miriam; Judge, Jasmeet; Zeng, Yijian; Su, Ye

2018-06-01

The process of evaporation interacts with the soil, which has various comprehensive mechanisms. Multiphase flow models solve air, vapour, water, and heat transport equations to simulate non-isothermal soil moisture transport of both liquid water and vapor flow, but are only applied in non-vegetated soils. For (sparsely) vegetated soils often energy balance models are used, however these lack the detailed information on non-isothermal soil moisture transport. In this study we coupled a multiphase flow model with a two-layer energy balance model to study the impact of non-isothermal soil moisture transport on evaporation fluxes (i.e., interception, transpiration, and soil evaporation) for vegetated soils. The proposed model was implemented at an experimental agricultural site in Florida, US, covering an entire maize-growing season (67 days). As the crops grew, transpiration and interception became gradually dominated, while the fraction of soil evaporation dropped from 100% to less than 20%. The mechanisms of soil evaporation vary depending on the soil moisture content. After precipitation the soil moisture content increased, exfiltration of the liquid water flow could transport sufficient water to sustain evaporation from soil, and the soil vapor transport was not significant. However, after a sufficient dry-down period, the soil moisture content significantly reduced, and the soil vapour flow significantly contributed to the upward moisture transport in topmost soil. A sensitivity analysis found that the simulations of moisture content and temperature at the soil surface varied substantially when including the advective (i.e., advection and mechanical dispersion) vapour transport in simulation, including the mechanism of advective vapour transport decreased soil evaporation rate under wet condition, while vice versa under dry condition. The results showed that the formulation of advective soil vapor transport in a soil-vegetation-atmosphere transfer continuum can affect the simulated evaporation fluxes, especially under dry condition.

Centrifugal lyophobic separator

NASA Technical Reports Server (NTRS)

Booth, F. W.; Bruce, R. A. (Inventor)

1974-01-01

A centrifugal separator is described using a lyophobic filter for removing liquid particles from a mixed stream of gas and liquid under various negative or positive external acceleration conditions as well as zero g or weightless conditions. Rotating the lyophobic filter and inclining the filter to the entering flow improves the lyophobic properties of the filter, provides gross separation of larger liquid particles, and prevents prolonged contact of liquid droplets with the spinning filter which might change the filter properties or block the filter.

Recirculating electric air filter

DOEpatents

Bergman, Werner

1986-01-01

An electric air filter cartridge has a cylindrical inner high voltage eleode, a layer of filter material, and an outer ground electrode formed of a plurality of segments moveably connected together. The outer electrode can be easily opened to remove or insert filter material. Air flows through the two electrodes and the filter material and is exhausted from the center of the inner electrode.

Recirculating electric air filter

DOEpatents

Bergman, W.

1985-01-09

An electric air filter cartridge has a cylindrical inner high voltage electrode, a layer of filter material, and an outer ground electrode formed of a plurality of segments moveably connected together. The outer electrode can be easily opened to remove or insert filter material. Air flows through the two electrodes and the filter material and is exhausted from the center of the inner electrode.

Effects of near soil surface characteristics on soil detachment by overland flow in a natural succession grassland

USDA-ARS?s Scientific Manuscript database

Vegetation restoration probably has great effects on the process of soil detachment. This study was conducted to investigate the effects of near soil surface characteristics on soil detachment by overland flow in a 7-year naturally restored grassland. Four treatments were designed to characterize th...

Methodology for Modeling the Microbial Contamination of Air Filters

PubMed Central

Joe, Yun Haeng; Yoon, Ki Young; Hwang, Jungho

2014-01-01

In this paper, we propose a theoretical model to simulate microbial growth on contaminated air filters and entrainment of bioaerosols from the filters to an indoor environment. Air filter filtration and antimicrobial efficiencies, and effects of dust particles on these efficiencies, were evaluated. The number of bioaerosols downstream of the filter could be characterized according to three phases: initial, transitional, and stationary. In the initial phase, the number was determined by filtration efficiency, the concentration of dust particles entering the filter, and the flow rate. During the transitional phase, the number of bioaerosols gradually increased up to the stationary phase, at which point no further increase was observed. The antimicrobial efficiency and flow rate were the dominant parameters affecting the number of bioaerosols downstream of the filter in the transitional and stationary phase, respectively. It was found that the nutrient fraction of dust particles entering the filter caused a significant change in the number of bioaerosols in both the transitional and stationary phases. The proposed model would be a solution for predicting the air filter life cycle in terms of microbiological activity by simulating the microbial contamination of the filter. PMID:24523908

Soil bioretention protects juvenile salmon and their prey from the toxic impacts of urban stormwater runoff.

PubMed

McIntyre, J K; Davis, J W; Hinman, C; Macneale, K H; Anulacion, B F; Scholz, N L; Stark, J D

2015-08-01

Green stormwater infrastructure (GSI), or low impact development, encompasses a diverse and expanding portfolio of strategies to reduce the impacts of stormwater runoff on natural systems. Benchmarks for GSI success are usually framed in terms of hydrology and water chemistry, with reduced flow and loadings of toxic chemical contaminants as primary metrics. Despite the central goal of protecting aquatic species abundance and diversity, the effectiveness of GSI treatments in maintaining diverse assemblages of sensitive aquatic taxa has not been widely evaluated. In the present study we characterized the baseline toxicity of untreated urban runoff from a highway in Seattle, WA, across six storm events. For all storms, first flush runoff was toxic to the daphniid Ceriodaphnia dubia, causing up to 100% mortality or impairing reproduction among survivors. We then evaluated whether soil media used in bioretention, a conventional GSI method, could reduce or eliminate toxicity to juvenile coho salmon (Oncorhynchus kisutch) as well as their macroinvertebrate prey, including cultured C. dubia and wild-collected mayfly nymphs (Baetis spp.). Untreated highway runoff was generally lethal to salmon and invertebrates, and this acute mortality was eliminated when the runoff was filtered through soil media in bioretention columns. Soil treatment also protected against sublethal reproductive toxicity in C. dubia. Thus, a relatively inexpensive GSI technology can be highly effective at reversing the acutely lethal and sublethal effects of urban runoff on multiple aquatic species. Copyright © 2014 The Authors. Published by Elsevier Ltd.. All rights reserved.

Similarity of plant functional traits and aggregation pattern in a subtropical forest

USGS Publications Warehouse

Zhang, Bo; Lu, Xiaozhen; Jiang, Jiang; DeAngelis, Donald L.; Fu, Zhiyuan; Zhang, Jinchi

2017-01-01

The distribution of species and communities in relation to environmental heterogeneity is a central focus in ecology. Co-occurrence of species with similar functional traits is an indication that communities are determined in part by environmental filters. However, few studies have been designed to test how functional traits are selectively filtered by environmental conditions at local scales. Exploring the relationship between soil characteristics and plant traits is a step toward understanding the filtering hypothesis in determining plant distribution at local scale. Toward this end, we mapped all individual trees (diameter >1 cm) in a one-ha subtropical forest of China in 2007 and 2015. We measured topographic and detailed soil properties within the field site, as well as plant leaf functional traits and demographic rates of the seven most common tree species. A second one-ha study plot was established in 2015, to test and validate the general patterns that were drawn from first plot. We found that variation in species distribution at local scale can be explained by soil heterogeneity and plant functional traits. (From first plot). (1) Species dominant in habitats with high soil ammonium nitrogen and total phosphorus tended to have high specific leaf area (SLA) and relative growth rate (RGR). (2) Species dominant in low-fertility habitats tended to have high leaf dry matter content (LDMC), ratio of chlorophyll a and b (ratioab), and leaf thickness (LT). The hypothesis that functional traits are selected in part by environmental filters and determine plant distribution at local scale was confirmed by the data of the first plot and a second regional site showed similar species distribution patterns.

Comparison of filter media materials for heavy metal removal from urban stormwater runoff using biofiltration systems.

PubMed

Lim, H S; Lim, W; Hu, J Y; Ziegler, A; Ong, S L

2015-01-01

The filter media in biofiltration systems play an important role in removing potentially harmful pollutants from urban stormwater runoff. This study compares the heavy metal removal potential (Cu, Zn, Cd, Pb) of five materials (potting soil, compost, coconut coir, sludge and a commercial mix) using laboratory columns. Total/dissolved organic carbon (TOC/DOC) was also analysed because some of the test materials had high carbon content which affects heavy metal uptake/release. Potting soil and the commercial mix offered the best metal uptake when dosed with low (Cu: 44.78 μg/L, Zn: 436.4 μg/L, Cd, 1.82 μg/L, Pb: 51.32 μg/L) and high concentrations of heavy metals (Cu: 241 μg/L, Zn: 1127 μg/L, Cd: 4.57 μg/L, Pb: 90.25 μg/L). Compost and sludge also had high removal efficiencies (>90%). Heavy metal leaching from these materials was negligible. A one-month dry period between dosing experiments did not affect metal removal efficiencies. TOC concentrations from all materials increased after the dry period. Heavy metal removal was not affected by filter media depth (600 mm vs. 300 mm). Heavy metals tended to accumulate at the upper 5 cm of the filter media although potting soil showed bottom-enriched concentrations. We recommend using potting soil as the principal media mixed with compost or sludge since these materials perform well and are readily available. The use of renewable materials commonly found in Singapore supports a sustainable approach to urban water management. Copyright © 2014 Elsevier Ltd. All rights reserved.

Hydrodynamics of Choanoflagellate Feeding

NASA Astrophysics Data System (ADS)

Andersen, Anders; Nielsen, Lasse Tor; Kiorboe, Thomas

2013-11-01

Choanoflagellate filter feeding is a poorly understood process. Studies indicate that the pressure differences created by the beating of the flagellum are insufficient to produce an adequate water flow through the collar filter, the mechanism believed to ultimately transport food particles to the cell. The collar is composed of numerous microvilli arranged as a palisade, and the low porosity of the filter provides high resistance to the water flow. Additionally, ultrastructural studies often show signs of mucus-like substances in and around the collar, potentially further hampering water flow. We present high-speed video of live material showing the particle retention and the beating of the flagellum in the choanoflagellate species Diaphanoeca grandis. We use the observations as input to model the low Reynolds number fluid dynamics of the fluid force produced by the flagellum and the resulting feeding flow.

Evaluating uncertainties in multi-layer soil moisture estimation with support vector machines and ensemble Kalman filtering

NASA Astrophysics Data System (ADS)

Liu, Di; Mishra, Ashok K.; Yu, Zhongbo

2016-07-01

This paper examines the combination of support vector machines (SVM) and the dual ensemble Kalman filter (EnKF) technique to estimate root zone soil moisture at different soil layers up to 100 cm depth. Multiple experiments are conducted in a data rich environment to construct and validate the SVM model and to explore the effectiveness and robustness of the EnKF technique. It was observed that the performance of SVM relies more on the initial length of training set than other factors (e.g., cost function, regularization parameter, and kernel parameters). The dual EnKF technique proved to be efficient to improve SVM with observed data either at each time step or at a flexible time steps. The EnKF technique can reach its maximum efficiency when the updating ensemble size approaches a certain threshold. It was observed that the SVM model performance for the multi-layer soil moisture estimation can be influenced by the rainfall magnitude (e.g., dry and wet spells).

Sorption of99mTc radiopharmaceutical compounds by soils

USGS Publications Warehouse

Jurisson, S.; Gawenis, J.; Landa, E.R.

2004-01-01

Study of the sorption of 99mTc radiopharmaceutical compounds by soils has assessed the fate of these compounds in the event of a surface spill and examined the potential of these compounds as hydrologic tracers. Sorption from deionized water, filtered Missouri River water, and artificial seawater by five surface soils was investigated. For all water types, the Tc radiopharmaceutical compounds showed greater sorption than the uncomplexed pertechnetate. The most lipophilic complexes showed the highest sorption on soils.

Radial Flow Fludized Filter Finds Niche as a Pretreatment System for Surface Water in Small Communities

EPA Science Inventory

An emerging technology called radial flow fluidized filter (R3f) has been developed as a low cost simplistic filtration technology for small communities of less than 10,000 people. Fouling is a major impediment to the sustainability of membrane technology particularly for small ...

A novel retinal vessel extraction algorithm based on matched filtering and gradient vector flow

NASA Astrophysics Data System (ADS)

Yu, Lei; Xia, Mingliang; Xuan, Li

2013-10-01

The microvasculature network of retina plays an important role in the study and diagnosis of retinal diseases (age-related macular degeneration and diabetic retinopathy for example). Although it is possible to noninvasively acquire high-resolution retinal images with modern retinal imaging technologies, non-uniform illumination, the low contrast of thin vessels and the background noises all make it difficult for diagnosis. In this paper, we introduce a novel retinal vessel extraction algorithm based on gradient vector flow and matched filtering to segment retinal vessels with different likelihood. Firstly, we use isotropic Gaussian kernel and adaptive histogram equalization to smooth and enhance the retinal images respectively. Secondly, a multi-scale matched filtering method is adopted to extract the retinal vessels. Then, the gradient vector flow algorithm is introduced to locate the edge of the retinal vessels. Finally, we combine the results of matched filtering method and gradient vector flow algorithm to extract the vessels at different likelihood levels. The experiments demonstrate that our algorithm is efficient and the intensities of vessel images exactly represent the likelihood of the vessels.

A GPU-Parallelized Eigen-Based Clutter Filter Framework for Ultrasound Color Flow Imaging.

PubMed

Chee, Adrian J Y; Yiu, Billy Y S; Yu, Alfred C H

2017-01-01

Eigen-filters with attenuation response adapted to clutter statistics in color flow imaging (CFI) have shown improved flow detection sensitivity in the presence of tissue motion. Nevertheless, its practical adoption in clinical use is not straightforward due to the high computational cost for solving eigendecompositions. Here, we provide a pedagogical description of how a real-time computing framework for eigen-based clutter filtering can be developed through a single-instruction, multiple data (SIMD) computing approach that can be implemented on a graphical processing unit (GPU). Emphasis is placed on the single-ensemble-based eigen-filtering approach (Hankel singular value decomposition), since it is algorithmically compatible with GPU-based SIMD computing. The key algebraic principles and the corresponding SIMD algorithm are explained, and annotations on how such algorithm can be rationally implemented on the GPU are presented. Real-time efficacy of our framework was experimentally investigated on a single GPU device (GTX Titan X), and the computing throughput for varying scan depths and slow-time ensemble lengths was studied. Using our eigen-processing framework, real-time video-range throughput (24 frames/s) can be attained for CFI frames with full view in azimuth direction (128 scanlines), up to a scan depth of 5 cm ( λ pixel axial spacing) for slow-time ensemble length of 16 samples. The corresponding CFI image frames, with respect to the ones derived from non-adaptive polynomial regression clutter filtering, yielded enhanced flow detection sensitivity in vivo, as demonstrated in a carotid imaging case example. These findings indicate that the GPU-enabled eigen-based clutter filtering can improve CFI flow detection performance in real time.

Modeling fecal bacteria transport and retention in agricultural and urban soils under saturated and unsaturated flow conditions.

PubMed

Balkhair, Khaled S

2017-03-01

Pathogenic bacteria, that enter surface water bodies and groundwater systems through unmanaged wastewater land application, pose a great risk to human health. In this study, six soil column experiments were conducted to simulate the vulnerability of agricultural and urban field soils for fecal bacteria transport and retention under saturated and unsaturated flow conditions. HYDRUS-1D kinetic attachment and kinetic attachment-detachment models were used to simulate the breakthrough curves of the experimental data by fitting model parameters. Results indicated significant differences in the retention and drainage of bacteria between saturated and unsaturated flow condition in the two studied soils. Flow under unsaturated condition retained more bacteria than the saturated flow case. The high bacteria retention in the urban soil compared to agricultural soil is ascribed not only to the dynamic attachment and sorption mechanisms but also to the greater surface area of fine particles and low flow rate. All models simulated experimental data satisfactorily under saturated flow conditions; however, under variably saturated flow, the peak concentrations were overestimated by the attachment-detachment model and underestimated by the attachment model with blocking. The good match between observed data and simulated concentrations by the attachment model which was supported by the Akaike information criterion (AIC) for model selection indicates that the first-order attachment coefficient was sufficient to represent the quantitative and temporal distribution of bacteria in the soil column. On the other hand, the total mass balance of the drained and retained bacteria in all transport experiments was in the range of values commonly found in the literature. Regardless of flow conditions and soil texture, most of the bacteria were retained in the top 12 cm of the soil column. The approaches and the models used in this study have proven to be a good tool for simulating fecal bacteria transport under a variety of initial and boundary flow conditions, hence providing a better understanding of the transport mechanism of bacteria as well as soil removal efficiency. Copyright © 2016 Elsevier Ltd. All rights reserved.

Multirate and event-driven Kalman filters for helicopter flight

NASA Technical Reports Server (NTRS)

Sridhar, Banavar; Smith, Phillip; Suorsa, Raymond E.; Hussien, Bassam

1993-01-01

A vision-based obstacle detection system that provides information about objects as a function of azimuth and elevation is discussed. The range map is computed using a sequence of images from a passive sensor, and an extended Kalman filter is used to estimate range to obstacles. The magnitude of the optical flow that provides measurements for each Kalman filter varies significantly over the image depending on the helicopter motion and object location. In a standard Kalman filter, the measurement update takes place at fixed intervals. It may be necessary to use a different measurement update rate in different parts of the image in order to maintain the same signal to noise ratio in the optical flow calculations. A range estimation scheme that accepts the measurement only under certain conditions is presented. The estimation results from the standard Kalman filter are compared with results from a multirate Kalman filter and an event-driven Kalman filter for a sequence of helicopter flight images.

Effect of soil properties on Hydraulic characteristics under subsurface drip irrigation

NASA Astrophysics Data System (ADS)

Fan, Wangtao; Li, Gang

2018-02-01

Subsurface drip irrigation (SDI) is a technique that has a high potential in application because of its high efficiency in water-saving. The hydraulic characteristics of SDI sub-unit pipe network can be affected by soil physical properties as the emitters are buried in soils. The related research, however, is not fully explored. The laboratory tests were carried out in the present study to determine the effects of hydraulic factors including operating pressure, initial soil water content, and bulk density on flow rate and its sensitivity to each hydraulic factor for two types of SDI emitters (PLASSIM emitter and Heping emitter). For this purpose, three soils with contrasting textures (i.e., light sand, silt loam, and light clay) were repacked with two soil bulk density (1.25 and1.40 g cm-3) with two initial soil water content (12% and 18%) in plexiglass columns with 40 cm in diameter and 40 cm in height. Drip emitters were buried at depth of 20 cm to measure the flow rates under seven operating pressures (60, 100, 150, 200, 250, 300, and 370 kPa). We found that the operating pressure was the dominating factor of flow rate of the SDI emitter, and flow rate increased with the increase of operating pressure. The initial soil water content and bulk density also affected the flow rate, and their effects were the most notable in the light sand soil. The sensitivity of flow rate to each hydraulic factor was dependent on soil texture, and followed a descending order of light sand>silt loam>light clay for both types of emitters. Further, the sensitivity of flow rate to each hydraulic factor decreased with the increase of operating pressure, initial soil water content, and bulk density. This study may be used to guide the soil specific-design of SDI emitters for optimal water use and management.

Evaluation of diffuse and preferential flow pathways of infiltrated precipitation and irrigation using oxygen and hydrogen isotopes

NASA Astrophysics Data System (ADS)

Ma, Bin; Liang, Xing; Liu, Shaohua; Jin, Menggui; Nimmo, John R.; Li, Jing

2017-05-01

Subsurface-water flow pathways in three different land-use areas (non-irrigated grassland, poplar forest, and irrigated arable land) in the central North China Plain were investigated using oxygen (18O) and hydrogen (2H) isotopes in samples of precipitation, soils, and groundwater. Soil water in the top 10 cm was significantly affected by both evaporation and infiltration. Water at 10-40 cm depth in the grassland and arable land, and 10-60 cm in poplar forest, showed a relatively short residence time, as a substantial proportion of antecedent soil water was mixed with a 92-mm storm infiltration event, whereas below those depths (down to 150 cm), depleted δ18O spikes suggested that some storm water bypassed the shallow soil layers. Significant differences, in soil-water content and δ18O values, within a small area, suggested that the proportion of immobile soil water and water flowing in subsurface pathways varies depending on local vegetation cover, soil characteristics and irrigation applications. Soil-water δ18O values revealed that preferential flow and diffuse flow coexist. Preferential flow was active within the root zone, independent of antecedent soil-water content, in both poplar forest and arable land, whereas diffuse flow was observed in grassland. The depleted δ18O spikes at 20-50 cm depth in the arable land suggested the infiltration of irrigation water during the dry season. Temporal isotopic variations in precipitation were subdued in the shallow groundwater, suggesting more complete mixing of different input waters in the unsaturated zone before reaching the shallow groundwater.

Are preferential flow paths perpetuated by microbial activity in the soil matrix? A review

NASA Astrophysics Data System (ADS)

Morales, Verónica L.; Parlange, J.-Yves; Steenhuis, Tammo S.

2010-10-01

SummaryRecently, the interactions between soil structure and microbes have been associated with water transport, retention and preferential or column flow development. Of particular significance is the potential impact of microbial extracellular polymeric substances (EPS) on soil porosity (i.e., hydraulic conductivity reduction or bioclogging) and of exudates from biota, including bacteria, fungi, roots and earthworms on the degree of soil water repellency. These structural and surface property changes create points of wetting instability, which under certain infiltrating conditions can often result in the formation of persistent preferential flow paths. Moreover, distinct differences in physical and chemical properties between regions of water flow (preferential flow paths) and no-flow (soil matrix) provide a unique set of environmental living conditions for adaptable microorganisms to exist. In this review, special consideration is given to: (1) the functional significance of microbial activity in the host porous medium in terms of feedback mechanisms instigated by irregular water availability and (2) the related physical and chemical conditions that force the organization and formation of unique microbial habitats in unsaturated soils that prompt and potentially perpetuate the formation of preferential flow paths in the vadose zone.

When and where does preferential flow matter - from observation to large scale modelling

NASA Astrophysics Data System (ADS)

Weiler, Markus; Leistert, Hannes; Steinbrich, Andreas

2017-04-01

Preferential flow can be of relevance in a wide range of soils and the interaction of different processes and factors are still difficult to assess. As most studies (including our own studies) focusing on the effect of preferential flow are based on relatively high precipitation rates, there is always the question how relevant preferential flow is under natural conditions, considering the site specific precipitation characteristics, the effect of the drying and wetting cycle on the initial soil water condition and shrinkage cracks, the site specific soil properties, soil structure and rock fragments, and the effect of plant roots and soil fauna (e.g. earthworm channels). In order to assess this question, we developed the distributed, process-based model RoGeR (Runoff Generation Research) to include a large number relevant features and processes of preferential flow in soils. The model was developed from a large number of process based research and experiments and includes preferential flow in roots, earthworm channels, along rock fragments and shrinkage cracks. We parameterized the uncalibrated model at a high spatial resolution of 5x5m for the whole state of Baden-Württemberg in Germany using LiDAR data, degree of sealing, landuse, soil properties and geology. As the model is an event based model, we derived typical event based precipitation characteristics based on rainfall duration, mean intensity and amount. Using the site-specific variability of initial soil moisture derived from a water balance model based on the same dataset, we simulated the infiltration and recharge amounts of all event classes derived from the event precipitation characteristics and initial soil moisture conditions. The analysis of the simulation results allowed us to extracts the relevance of preferential flow for infiltration and recharge considering all factors above. We could clearly see a strong effect of the soil properties and land-use, but also, particular for clay rich soils a strong effect of the initial conditions due to the development of soil cracks. Not too surprisingly, the relevance of preferential flow was much lower when considering the whole range of precipitation events as only considering events with a high rainfall intensity. Also, the influence on infiltration and recharge were different. Despite the model can still be improved in particular considering more realistic information about the spatial and temporal variability of preferential flow by soil fauna and plants, the model already shows under what situation we need to be very careful when predicting infiltration and recharge with models considering only longer time steps (daily) or only matrix flow.

A comparative CFD study of four inferior vena cava filters.

PubMed

López, Josep M; Fortuny, Gerard; Puigjaner, Dolors; Herrero, Joan; Marimon, Francesc

2018-03-30

Computational fluid dynamics was used to simulate the flow of blood within an inferior vena cava (IVC) geometry model that was reconstructed from computed tomography images obtained from a real patient. The main novelty of the present work is that we simulated the implantation of 4 different filter models in this realistic IVC geometry. We considered different blood flow rates in the range between V in =20 and V in =80 cm 3 /s, and all simulations were performed with both the Newtonian and a non-Newtonian model for the blood viscosity. We compared the hemodynamics performance of the different filter models, and we paid a special attention to the total drag force, F d , exerted by the blood flow on the filter surface. This force is the sum of 2 contributions: the viscous skin friction force, which was found to be roughly proportional to the filter surface area, and the pressure force, which depended on the particular filter geometry design. The F d force is relevant because it must be balanced by the total force exerted by the filter hooks/struts on the IVC wall at the attachment locations. For the highest V in value investigated, the variation in F d among filters was from 116 to 308 dyne. We also showed how the present results can be extrapolated to obtain good estimates of the drag forces if the blood viscosity levels change, ie, if the patient with a filter implanted is treated with anticoagulant therapy. Copyright © 2018 John Wiley & Sons, Ltd.

Soil shapes community structure through fire.

PubMed

Ojeda, Fernando; Pausas, Juli G; Verdú, Miguel

2010-07-01

Recurrent wildfires constitute a major selecting force in shaping the structure of plant communities. At the regional scale, fire favours phenotypic and phylogenetic clustering in Mediterranean woody plant communities. Nevertheless, the incidence of fire within a fire-prone region may present strong variations at the local, landscape scale. This study tests the prediction that woody communities on acid, nutrient-poor soils should exhibit more pronounced phenotypic and phylogenetic clustering patterns than woody communities on fertile soils, as a consequence of their higher flammability and, hence, presumably higher propensity to recurrent fire. Results confirm the predictions and show that habitat filtering driven by fire may be detected even in local communities from an already fire-filtered regional flora. They also provide a new perspective from which to consider a preponderant role of fire as a key evolutionary force in acid, infertile Mediterranean heathlands.

The potential of remotely sensed soil moisture for operational flood forecasting

NASA Astrophysics Data System (ADS)

Wanders, N.; Karssenberg, D.; de Roo, A.; de Jong, S.; Bierkens, M. F.

2013-12-01

Nowadays, remotely sensed soil moisture is readily available from multiple space born sensors. The high temporal resolution and global coverage make these products very suitable for large-scale land-surface applications. The potential to use these products in operational flood forecasting has thus far not been extensively studied. In this study, we evaluate the added value of assimilated remotely sensed soil moisture for the European Flood Awareness System (EFAS) and its potential to improve the timing and height of the flood peak and low flows. EFAS is used for operational flood forecasting in Europe and uses a distributed hydrological model for flood predictions for lead times up to 10 days. Satellite-derived soil moisture from ASCAT, AMSR-E and SMOS is assimilated into the EFAS system for the Upper Danube basin and results are compared to assimilation of only discharge observations. Discharge observations are available at the outlet and at six additional locations throughout the catchment. To assimilate soil moisture data into EFAS, an Ensemble Kalman Filter (EnKF) is used. Information on the spatial (cross-) correlation of the errors in the satellite products, derived from a detailed model-satellite soil moisture comparison study, is included to ensure optimal performance of the EnKF. For the validation, additional discharge observations not used in the EnKF are used as an independent validation dataset. Our results show that the accuracy of flood forecasts is increased when more discharge observations are used in that the Mean Absolute Error (MAE) of the ensemble mean is reduced by 65%. The additional inclusion of satellite data results in a further increase of the performance: forecasts of base flows are better and the uncertainty in the overall discharge is reduced, shown by a 10% reduction in the MAE. In addition, floods are predicted with a higher accuracy and the Continuous Ranked Probability Score (CRPS) shows a performance increase of 10-15% on average, compared to assimilation of discharge only. The rank histograms show that the forecast is not biased. The timing errors in the flood predictions are decreased when soil moisture data is used and imminent floods can be forecasted with skill one day earlier. In conclusion, our study shows that assimilation of satellite soil moisture increases the performance of flood forecasting systems for large catchments, like the Upper Danube. The additional gain is highest when discharge observations from both upstream and downstream areas are used in combination with the soil moisture data. These results show the potential of future soil moisture missions with a higher spatial resolution like SMAP to improve near-real time flood forecasting in large catchments.

Simulated formation and flow of microemulsions during surfactant flushing of contaminated soil.

PubMed

Ouyan, Ying; Cho, Jong Soo; Mansell, Robert S

2002-01-01

Contamination of groundwater resources by non-aqueous phase liquids (NAPLs) has become an issue of increasing environmental concern. This study investigated the formation and flow of microemulsions during surfactant flushing of NAPL-contaminated soil using the finite difference model UTCHEM, which was verified with our laboratory experimental data. Simulation results showed that surfactant flushing of NAPLs (i.e., trichloroethylene and tetrachloroethylene) from the contaminated soils was an emulsion-driven process. Formation of NAPL-in-water microemulsions facilitated the removal of NAPLs from contaminated soils. Changes in soil saturation pressure were used to monitor the mobilization and entrapment of NAPLs during surface flushing process. In general, more NAPLs were clogged in soil pores when the soil saturation pressure increased. Effects of aquifer salinity on the formation and flow of NAPL-in-water microemulsions were significant. This study suggests that the formation and flow of NAPL-in-water microemulsions through aquifer systems are complex physical-chemical phenomena that are critical to effective surfactant flushing of contaminated soils.

On the large eddy simulation of turbulent flows in complex geometry

NASA Technical Reports Server (NTRS)

Ghosal, Sandip

1993-01-01

Application of the method of Large Eddy Simulation (LES) to a turbulent flow consists of three separate steps. First, a filtering operation is performed on the Navier-Stokes equations to remove the small spatial scales. The resulting equations that describe the space time evolution of the 'large eddies' contain the subgrid-scale (sgs) stress tensor that describes the effect of the unresolved small scales on the resolved scales. The second step is the replacement of the sgs stress tensor by some expression involving the large scales - this is the problem of 'subgrid-scale modeling'. The final step is the numerical simulation of the resulting 'closed' equations for the large scale fields on a grid small enough to resolve the smallest of the large eddies, but still much larger than the fine scale structures at the Kolmogorov length. In dividing a turbulent flow field into 'large' and 'small' eddies, one presumes that a cut-off length delta can be sensibly chosen such that all fluctuations on a scale larger than delta are 'large eddies' and the remainder constitute the 'small scale' fluctuations. Typically, delta would be a length scale characterizing the smallest structures of interest in the flow. In an inhomogeneous flow, the 'sensible choice' for delta may vary significantly over the flow domain. For example, in a wall bounded turbulent flow, most statistical averages of interest vary much more rapidly with position near the wall than far away from it. Further, there are dynamically important organized structures near the wall on a scale much smaller than the boundary layer thickness. Therefore, the minimum size of eddies that need to be resolved is smaller near the wall. In general, for the LES of inhomogeneous flows, the width of the filtering kernel delta must be considered to be a function of position. If a filtering operation with a nonuniform filter width is performed on the Navier-Stokes equations, one does not in general get the standard large eddy equations. The complication is caused by the fact that a filtering operation with a nonuniform filter width in general does not commute with the operation of differentiation. This is one of the issues that we have looked at in detail as it is basic to any attempt at applying LES to complex geometry flows. Our principal findings are summarized.

An approach for using soil surveys to guide the placement of water quality buffers

Treesearch

M.G. Dosskey; M.J. Helmers; D.E. Eisenhauer

2006-01-01

Vegetative buffers may function better for filtering agricultural runoff in some locations than in others because of intrinsic characteristics of the land on which they are placed. The objective of this study was to develop a method based on soil survey attributes that can be used to compare soil map units for how effectively a buffer installed in them could remove...

SITE AMPLIFICATION OF EARTHQUAKE GROUND MOTION.

USGS Publications Warehouse

Hays, Walter W.

1986-01-01

When analyzing the patterns of damage in an earthquake, physical parameters of the total earthquake-site-structure system are correlated with the damage. Soil-structure interaction, the cause of damage in many earthquakes, involves the frequency-dependent response of both the soil-rock column and the structure. The response of the soil-rock column (called site amplification) is controversial because soil has strain-dependent properties that affect the way the soil column filters the input body and surface seismic waves, modifying the amplitude and phase spectra and the duration of the surface ground motion.

14 CFR 23.1019 - Oil strainer or filter.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Oil strainer or filter. 23.1019 Section 23....1019 Oil strainer or filter. (a) Each turbine engine installation must incorporate an oil strainer or filter through which all of the engine oil flows and which meets the following requirements: (1) Each oil...

14 CFR 23.1019 - Oil strainer or filter.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Oil strainer or filter. 23.1019 Section 23....1019 Oil strainer or filter. (a) Each turbine engine installation must incorporate an oil strainer or filter through which all of the engine oil flows and which meets the following requirements: (1) Each oil...

14 CFR 23.1019 - Oil strainer or filter.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Oil strainer or filter. 23.1019 Section 23....1019 Oil strainer or filter. (a) Each turbine engine installation must incorporate an oil strainer or filter through which all of the engine oil flows and which meets the following requirements: (1) Each oil...

14 CFR 23.1019 - Oil strainer or filter.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Oil strainer or filter. 23.1019 Section 23....1019 Oil strainer or filter. (a) Each turbine engine installation must incorporate an oil strainer or filter through which all of the engine oil flows and which meets the following requirements: (1) Each oil...

14 CFR 23.1019 - Oil strainer or filter.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Oil strainer or filter. 23.1019 Section 23....1019 Oil strainer or filter. (a) Each turbine engine installation must incorporate an oil strainer or filter through which all of the engine oil flows and which meets the following requirements: (1) Each oil...

Water Filters

NASA Technical Reports Server (NTRS)

1987-01-01

A compact, lightweight electrolytic water filter generates silver ions in concentrations of 50 to 100 parts per billion in the water flow system. Silver ions serve as effective bactericide/deodorizers. Ray Ward requested and received from NASA a technical information package on the Shuttle filter, and used it as basis for his own initial development, a home use filter.

Overland flow generation mechanisms affected by topsoil treatment: Application to soil conservation

NASA Astrophysics Data System (ADS)

González Paloma, Hueso; Juan Francisco, Martinez-Murillo; Damian, Ruiz-Sinoga Jose; Hanoch, Lavee

2015-04-01

Hortonian overland-flow is responsible for significant amounts of soil loss in Mediterranean geomorphological systems. Restoring the native vegetation is the most effective way to control runoff and sediment yield. During the seeding and plant establishment, vegetation cover may be better sustained if soil is amended with an external source. Four amendments were applied in an experimental set of plots: straw mulching (SM); mulch with chipped branches of Aleppo Pine (Pinus halepensis L.) (PM); TerraCotten hydroabsobent polymers (HP); sewage sludge (RU); and control (C). Plots were afforested following the same spatial pattern, and amendments were mixed with the soil at the rate 10 Mg ha-1. This research demonstrates the role played by the treatments in overland flow generation mechanism (runoff, overland flow and soil moisture along the soil profile). The general overland flow characteristics showed that in the C plots the average overland flow was 8.0 ± 22.0 l per event, and the HP plots produced a similar mean value (8.1 ± 20.1 l). The average overland flow per event was significantly less for soil amended with SM, PM or RU (2.7 ± 8.3 l; 1.3 ± 3.5 l and 2.2 ± 5.9 l, respectively). There was a similar trend with respect to the maximum overland flow. The mean sediment yield per event was relatively high in the C and HP plots (8.6 ± 27.8 kg and 14.8 ± 43.4 kg, respectively), while significantly lower values were registered in the SM, PM and RU plots (0.4 ± 1.0 kg; 0.2 ± 0.3 kg and 0.2 ± 0.3 kg, respectively). Very similar trends were found for the maximum sediment yield. Regarding to the soil moisture values, there was a difference in the trends between the C and HP plots and the SM, PM and RU plots. In the C and HP plots the general trend was for a decrease in soil moisture downward through the soil profile, while in the SM, PM and RU plots the soil moisture remained relatively constant or increased, except for the RU treatment in which the soil moisture decreased from 5 to 10 cm depth. According to the results, the hydrological and erosive response in the five treatments showed dissimilarities, despite having similar rainfall exposure and the same original soil properties. This means that the differences between the treatments play a key role in the soil moisture, overland flow and sediment yield values. The study has demonstrated the effects of various treatments on the generation of overland flow, and hence the sediment yield. In the C and HP plots, relatively large amounts of overland flow rapidly developed. This cannot be explained by saturation conditions, as the soil moisture content was highest near the surface and decreased with depth in the profile. This, together with the relatively low macro-porosity, proved that the mechanism of overland flow generation was of the Hortonian type. On the other hand, in the SM and PM plots, the high level of macro-porosity, together with the increase in soil moisture content with depth, explained the small quantities of overland flow and sediment yield. In the rare case that overland flow developed in these plots, it was minor in amount, and yielded little sediment because of saturation conditions. The processes in the RU plots were more complicated; from 10 cm depth the soil moisture content always increased with further depth, usually rapidly. Thus, water infiltrated continuously and there was no rainfall excess. Therefore, in terms of overland flow and sediment yield, the RU plots behaved in a similar way to the SM and PM plots. The fact that the soil moisture content was low at depths of 10 cm is because of the uptake of water at these depths by the roots of Carlina hispanica Lam. From a land management standpoint, the SM, PM and RU treatments were the most effective in reducing overland flow and sediment yield following afforestation. In addition, the soil profile became more wettable, which provided more water to support plant survival. However, when afforestation was combined with RU treatment, the vegetation cover resulting from the amendment treatment was the main factor controlling the hydrological processes. Application of the HP treatment caused a decrease in soil moisture content with depth in the soil profile, and overland flow and sediment yield were maximum in this treatment.

Partial nitrification of non-ammonium-rich wastewater within biofilm filters under ambient temperature.

PubMed

Wang, Hongyu; He, Jiajie; Yang, Kai

2010-01-01

This study evaluated the partial nitrification performances of two biofilm filters over a synthetic non-ammonium-rich wastewater at a 20°C room temperature under both limited DO (∼2.0 mg/L) and unlimited DO (∼4.0 mg/L) conditions. The two filters were each of 80 cm long and used different biofilm carriers: activated carbon and ceramic granule. Results showed that partial nitrification was accomplished for both filters under the limited DO condition. However, the effluent NO(2)-N was higher in the ceramic granule filter than in the activated carbon filter, and was less susceptible to the influent COD/N changes. Further investigation into the water phase COD and NH(4)-N depth profiles and bacteria population within the two filters showed that by putting upper filter layer (upstream) to confront relatively higher influent COD/N ratios, the filtration process naturally put lower filter layers (downstream) relatively more favorable for nitrifying bacteria (ammonia oxidizing bacteria in this study) to prosper, making the filter depth left for nitrification a crucial factor for the effectiveness of nitrification with a filter. The potentially different porous flow velocities of the two filters might be the reason to cause their different partial nitrification performances, with a lower porous flow velocity (the ceramic granule filter) favoring partial nitrification more. In summation, DO, filter depth, and filtration speed should be played together to successfully operate a biofilm filter for partial nitrification.

Identification of runoff formation with two dyes in a mid-latitude mountain headwater

NASA Astrophysics Data System (ADS)

Vlcek, Lukas; Schneider, Philipp; Falatkova, Kristyna

2017-04-01

There have been numerous studies on subsurface flow in peat bog areas, as both water scarcity and floods have led to increased attention to this specific environment and its role within the hydrological cycle. In contrast, this experimental study identifies runoff formation at two opposite hillslopes in a peaty mountain headwater; a slope with organic soils (Peat / Histosol) and shallow groundwater ( 0.5 m below surface) complemented by a slope with mineral soils (Podzol) and no detectable groundwater within 2 m below surface. Differences in infiltration, percolation, and preferential flowpaths between both hillslopes could be identified by sprinkling experiments with two dyes - Brilliant Blue FCF and Fluorescein. By excavating dye-stained soil profiles parallel ("lateral") and perpendicular ("frontal") to the slopes' gradients - both within and downstream of the sprinkling plots - dye stained flow patterns in the soil could be clearly identified. The results show that biomat flow occurred at both hillslopes. The dye solutions infiltrated into the soil and continued either as lateral subsurface pipeflow (SSF), in the case of the Peat Bog, or percolated vertically towards the bedrock in the case of the Podzol. The study provides evidence that biomat flow (BMF) - shallow, lateral preferential flowpaths along decomposed tree roots or logs - is a major runoff formation process at the Peat Bog hillslope and in the adjacent riparian zone. This lateral flow through the organic soil hillslope (Peat Bog) towards the stream occurred mainly as shallow subsurface flow in organic layers above the groundwater level (BMF and SSF), but water partly percolates to the shallow groundwater via vertical macropores as well . In contrast, the mineral soil hillslope (Podzol) was mostly dominated by vertical percolation. Lateral flow occurred only on short distances in the organic topsoil as biomat flow (BMF). The sorptive tracer Brilliant Blue FCF successfully stained flowpaths in the soil at both hillslopes, whereas the identification of soil staining patterns by the relatively conservative tracer Fluorescein was limited on organic soil profiles.

On the importance of measurement error correlations in data assimilation for integrated hydrological models

NASA Astrophysics Data System (ADS)

Camporese, Matteo; Botto, Anna

2017-04-01

Data assimilation is becoming increasingly popular in hydrological and earth system modeling, as it allows us to integrate multisource observation data in modeling predictions and, in doing so, to reduce uncertainty. For this reason, data assimilation has been recently the focus of much attention also for physically-based integrated hydrological models, whereby multiple terrestrial compartments (e.g., snow cover, surface water, groundwater) are solved simultaneously, in an attempt to tackle environmental problems in a holistic approach. Recent examples include the joint assimilation of water table, soil moisture, and river discharge measurements in catchment models of coupled surface-subsurface flow using the ensemble Kalman filter (EnKF). One of the typical assumptions in these studies is that the measurement errors are uncorrelated, whereas in certain situations it is reasonable to believe that some degree of correlation occurs, due for example to the fact that a pair of sensors share the same soil type. The goal of this study is to show if and how the measurement error correlations between different observation data play a significant role on assimilation results in a real-world application of an integrated hydrological model. The model CATHY (CATchment HYdrology) is applied to reproduce the hydrological dynamics observed in an experimental hillslope. The physical model, located in the Department of Civil, Environmental and Architectural Engineering of the University of Padova (Italy), consists of a reinforced concrete box containing a soil prism with maximum height of 3.5 m, length of 6 m, and width of 2 m. The hillslope is equipped with sensors to monitor the pressure head and soil moisture responses to a series of generated rainfall events applied onto a 60 cm thick sand layer overlying a sandy clay soil. The measurement network is completed by two tipping bucket flow gages to measure the two components (subsurface and surface) of the outflow. By collecting data at a temporal resolution of 0.5 Hz (relatively high, compared to the hydrological dynamics), we can perform a comprehensive statistical analysis of the observations, including the cross-correlations between data from different sensors. We report on the impact of taking these correlations into account in a series of assimilation scenarios, where the EnKF is used to assimilate pressure head and/or soil moisture and/or subsurface outflow.

Performance of Improved High-Order Filter Schemes for Turbulent Flows with Shocks

NASA Technical Reports Server (NTRS)

Kotov, Dmitry Vladimirovich; Yee, Helen M C.

2013-01-01

The performance of the filter scheme with improved dissipation control ? has been demonstrated for different flow types. The scheme with local ? is shown to obtain more accurate results than its counterparts with global or constant ?. At the same time no additional tuning is needed to achieve high accuracy of the method when using the local ? technique. However, further improvement of the method might be needed for even more complex and/or extreme flows.

Optimization of flow cytometric detection and cell sorting of transgenic Plasmodium parasites using interchangeable optical filters

PubMed Central

2012-01-01

Background Malaria remains a major cause of morbidity and mortality worldwide. Flow cytometry-based assays that take advantage of fluorescent protein (FP)-expressing malaria parasites have proven to be valuable tools for quantification and sorting of specific subpopulations of parasite-infected red blood cells. However, identification of rare subpopulations of parasites using green fluorescent protein (GFP) labelling is complicated by autofluorescence (AF) of red blood cells and low signal from transgenic parasites. It has been suggested that cell sorting yield could be improved by using filters that precisely match the emission spectrum of GFP. Methods Detection of transgenic Plasmodium falciparum parasites expressing either tdTomato or GFP was performed using a flow cytometer with interchangeable optical filters. Parasitaemia was evaluated using different optical filters and, after optimization of optics, the GFP-expressing parasites were sorted and analysed by microscopy after cytospin preparation and by imaging cytometry. Results A new approach to evaluate filter performance in flow cytometry using two-dimensional dot blot was developed. By selecting optical filters with narrow bandpass (BP) and maximum position of filter emission close to GFP maximum emission in the FL1 channel (510/20, 512/20 and 517/20; dichroics 502LP and 466LP), AF was markedly decreased and signal-background improve dramatically. Sorting of GFP-expressing parasite populations in infected red blood cells at 90 or 95% purity with these filters resulted in 50-150% increased yield when compared to the standard filter set-up. The purity of the sorted population was confirmed using imaging cytometry and microscopy of cytospin preparations of sorted red blood cells infected with transgenic malaria parasites. Discussion Filter optimization is particularly important for applications where the FP signal and percentage of positive events are relatively low, such as analysis of parasite-infected samples with in the intention of gene-expression profiling and analysis. The approach outlined here results in substantially improved yield of GFP-expressing parasites, and requires decreased sorting time in comparison to standard methods. It is anticipated that this protocol will be useful for a wide range of applications involving rare events. PMID:22950515

Optimized Extraction Method To Remove Humic Acid Interferences from Soil Samples Prior to Microbial Proteome Measurements.

PubMed

Qian, Chen; Hettich, Robert L

2017-07-07

The microbial composition and their activities in soil environments play a critical role in organic matter transformation and nutrient cycling. Liquid chromatography coupled to high-performance mass spectrometry provides a powerful approach to characterize soil microbiomes; however, the limited microbial biomass and the presence of abundant interferences in soil samples present major challenges to proteome extraction and subsequent MS measurement. To this end, we have designed an experimental method to improve microbial proteome measurement by removing the soil-borne humic substances coextraction from soils. Our approach employs an in situ detergent-based microbial lysis/TCA precipitation coupled to an additional cleanup step involving acidified precipitation and filtering at the peptide level to remove most of the humic acid interferences prior to proteolytic peptide measurement. The novelty of this approach is an integration to exploit two different characteristics of humic acids: (1) Humic acids are insoluble in acidic solution but should not be removed at the protein level, as undesirable protein removal may also occur. Rather it is better to leave the humics acids in the samples until the peptide level, at which point the significant differential solubility of humic acids versus peptides at low pH can be exploited very efficiently. (2) Most of the humic acids have larger molecule weights than the peptides. Therefore, filtering a pH 2 to 3 peptide solution with a 10 kDa filter will remove most of the humic acids. This method is easily interfaced with normal proteolytic processing approaches and provides a reliable and straightforward protein extraction method that efficiently removes soil-borne humic substances without inducing proteome sample loss or biasing protein identification in mass spectrometry. In general, this humic acid removal step is universal and can be adopted by any workflow to effectively remove humic acids to avoid them negatively competing with peptides for binding with reversed-phase resin or ionization in the electrospray.

Remotely serviced filter and housing

DOEpatents

Ross, M.J.; Zaladonis, L.A.

1987-07-22

A filter system for a hot cell comprises a housing adapted for input of air or other gas to be filtered, flow of the air through a filter element, and exit of filtered air. The housing is tapered at the top to make it easy to insert a filter cartridge holds the filter element while the air or other gas is passed through the filter element. Captive bolts in trunnion nuts are readily operated by electromechanical manipulators operating power wrenches to secure and release the filter cartridge. The filter cartridge is adapted to make it easy to change a filter element by using a master-slave manipulator at a shielded window station. 6 figs.

'Laguna Hollow'Undisturbed

NASA Technical Reports Server (NTRS)

2004-01-01

This image shows the patch of soil at the bottom of the shallow depression dubbed 'Laguna Hollow' where the Mars Exploration Rover Spirit will soon begin trenching. Scientists are intrigued by the clustering of small pebbles and the crack-like fine lines, which indicate a coherent surface that expands and contracts. A number of processes can cause materials to expand and contract, including cycles of heating and cooling; freezing and thawing; and rising and falling of salty liquids within a substance. This false-color image was created using the blue, green and infrared filters of the rover's panoramic camera. Scientists chose this particular combination of filters to enhance the heterogeneity of the martian soil.

Identifying fecal matter contamination in produce fields using multispectral reflectance imaging under ambient solar illumination

NASA Astrophysics Data System (ADS)

Everard, Colm D.; Kim, Moon S.; Lee, Hoonsoo; O'Donnell, Colm P.

2016-05-01

An imaging device to detect fecal contamination in fresh produce fields could allow the producer avoid harvesting fecal contaminated produce. E.coli O157:H7 outbreaks have been associated with fecal contaminated leafy greens. In this study, in-field spectral profiles of bovine fecal matter, soil, and spinach leaves are compared. A common aperture imager designed with two identical monochromatic cameras, a beam splitter, and optical filters was used to simultaneously capture two-spectral images of leaves contaminated with both fecal matter and soil. The optical filters where 10 nm full width half maximum bandpass filters, one at 690 nm and the second at 710 nm. These were mounted in front of the object lenses. New images were created using the ratio of these two spectral images on a pixel by pixel basis. Image analysis results showed that the fecal matter contamination could be distinguished from soil and leaf on the ratio images. The use of this technology has potential to allow detection of fecal contamination in produce fields which can be a source of foodbourne illnesses. It has the added benefit of mitigating cross-contamination during harvesting and processing.

Implicit LES using adaptive filtering

NASA Astrophysics Data System (ADS)

Sun, Guangrui; Domaradzki, Julian A.

2018-04-01

In implicit large eddy simulations (ILES) numerical dissipation prevents buildup of small scale energy in a manner similar to the explicit subgrid scale (SGS) models. If spectral methods are used the numerical dissipation is negligible but it can be introduced by applying a low-pass filter in the physical space, resulting in an effective ILES. In the present work we provide a comprehensive analysis of the numerical dissipation produced by different filtering operations in a turbulent channel flow simulated using a non-dissipative, pseudo-spectral Navier-Stokes solver. The amount of numerical dissipation imparted by filtering can be easily adjusted by changing how often a filter is applied. We show that when the additional numerical dissipation is close to the subgrid-scale (SGS) dissipation of an explicit LES the overall accuracy of ILES is also comparable, indicating that periodic filtering can replace explicit SGS models. A new method is proposed, which does not require any prior knowledge of a flow, to determine the filtering period adaptively. Once an optimal filtering period is found, the accuracy of ILES is significantly improved at low implementation complexity and computational cost. The method is general, performing well for different Reynolds numbers, grid resolutions, and filter shapes.

The relationship of catchment topography and soil hydraulic characteristics to lake alkalinity in the northeastern United States

USGS Publications Warehouse

Wolock, D.M.; Hornberger, G.M.; Beven, K.J.; Campbell, W.G.

1989-01-01

We undertook the task of determining whether base flow alkalinity of surface waters in the northeastern United States is related to indices of soil contact time and flow path partitioning that are derived from topographic and soils information. The influence of topography and soils on catchment hydrology has been incorporated previously in the variable source area model TOPMODEL as the relative frequency distribution of ln (a/Kb tan B), where ln is the Naperian logarithm, “a” is the area drained per unit contour, K is the saturated hydraulic conductivity, b is the soil depth, and tan B is the slope. Using digital elevation and soil survey data, we calculated the ln (a/Kb tan B) distribution for 145 catchments. Indices of flow path partitioning and soil contact time were derived from the ln (a/Kb tan B) distributions and compared to measurements of alkalinity in lakes to which the catchments drain. We found that alkalinity was, in general, positively correlated with the index of soil contact time, whereas the correlation between alkalinity and the flow path partitioning index was weak at best. A portion of the correlation between the soil contact time index and alkalinity was attributable to covariation with soil base saturation and cation exchange capacity, while another portion was found to be independent of these factors. Although our results indicate that catchments with long soil contact time indices are most likely to produce high alkalinity base flow, a sensitivity analysis of TOPMODEL suggests that surface waters of these same watersheds may be susceptible to alkalinity depressions during storm events, due to the role of flow paths.

Revisiting Atmospheric Lead in NYC - Comparison of Archived Air Filters to Urban Park Sediments and Soils

NASA Astrophysics Data System (ADS)

Chillrud, S. N.; Ross, J. M.; Yan, B.; Bopp, R.

2015-12-01

Urban lake sediments have the potential to be used for reconstructing history of aerosols, providing data before the start of urban air quality monitoring. In a previous study, the similarity between radionuclide and excess Pb inventories (57 g/m^2) in Central Park Lake (CPL) sediments and those same parameters in Central Park soils (CPS) was interpreted to indicate that urban lake sediment cores from CPL represent deposition of atmospheric aerosols over the history of the park, which was constructed in the 1860s. Furthermore, metal ratios and metal chronologies indicated that incineration was the major source of Pb to the NYC atmosphere over the 20th century. In this report, we compare the lake chronologies for metals to a set of archived air filters collected by the Department of Energy's Environmental Measurement Lab (EML). These weekly filters of total suspended particulates (TSP) were collected by a high volume sampler located in lower Manhattan for radionuclides as part of the program focused on documenting radioactive fallout from nuclear weapons testing. Metal concentrations measured in subsamples of the EML filters collected between the 1970s to 1990s showed Pb decreasing more slowly than the records of Pb added to gasoline. Metal ratios in the filters were similar to the ratios measured in CPL sediments; the Pb to Sn ratios were roughly 20:1 and the Pb to Zn ratios were in close to 1. The similarity of the ratios provides additional solid support that the CP Lake sediment cores reflect atmospheric inputs. The enrichment of Pb in the large aerosol particle fraction (TSP), relative to fine PM2.5 fraction, demonstrates that the resuspended NYC soils and their historical contaminant burden, are the primary, current source of Pb to NYC air.

Performance evaluation of a dual-flow recharge filter for improving groundwater quality.

PubMed

Samuel, Manoj P; Senthilvel, S; Mathew, Abraham C

2014-07-01

A dual-flow multimedia stormwater filter integrated with a groundwater recharge system was developed and tested for hydraulic efficiency and pollutant removal efficiency. The influent stormwater first flows horizontally through the circular layers of planted grass and biofibers. Subsequently, the flow direction changes to a vertical direction so that water moves through layers of pebbles and sand and finally gets recharged to the deep aquifers. The media in the sequence of vegetative medium:biofiber to pebble:sand were filled in nine proportions and tested for the best performing combination. Three grass species, viz., Typha (Typha angustifolia), Vetiver (Chrysopogon zizanioides), and St. Augustine grass (Stenotaphrum secundatum), were tested as the best performing vegetative medium. The adsorption behavior of Coconut (Cocos nucifera) fiber, which was filled in the middle layer, was determined by a series of column and batch studies.The dual-flow filter showed an increasing trend in hydraulic efficiency with an increase in flowrate. The chemical removal efficiency of the recharge dual-flow filter was found to be very high in case of K+ (81.6%) and Na+ (77.55%). The pH normalizing efficiency and electrical conductivity reduction efficiency were also recorded as high. The average removal percentage of Ca2+ was moderate, while that of Mg2+ was very low. The filter proportions of 1:1 to 1:2 (plant:fiber to pebble:sand) showed a superior performance compared to all other proportions. Based on the estimated annual costs and returns, all the financial viability criteria (internal rate of return, net present value, and benefit-cost ratio) were found to be favorable and affordable to farmers in terms of investing in the developed filtration system.

Calibration of a field-scale Soil and Water Assessment Tool (SWAT) model with field placement of best management practices in Alger Creek, Michigan

USGS Publications Warehouse

Merriman-Hoehne, Katherine R.; Russell, Amy M.; Rachol, Cynthia M.; Daggupati, Prasad; Srinivasan, Raghavan; Hayhurst, Brett A.; Stuntebeck, Todd D.

2018-01-01

Subwatersheds within the Great Lakes “Priority Watersheds” were targeted by the Great Lakes Restoration Initiative (GLRI) to determine the effectiveness of the various best management practices (BMPs) from the U.S. Department of Agriculture-Natural Resources Conservation Service National Conservation Planning (NCP) Database. A Soil and Water Assessment Tool (SWAT) model is created for Alger Creek, a 50 km2 tributary watershed to the Saginaw River in Michigan. Monthly calibration yielded very good Nash–Sutcliffe efficiency (NSE) ratings for flow, sediment, total phosphorus (TP), dissolved reactive phosphorus (DRP), and total nitrogen (TN) (0.90, 0.79, 0.87, 0.88, and 0.77, respectively), and satisfactory NSE rating for nitrate (0.51). Two-year validation results in at least satisfactory NSE ratings for flow, sediment, TP, DRP, and TN (0.83, 0.54, 0.73, 0.53, and 0.60, respectively), and unsatisfactory NSE rating for nitrate (0.28). The model estimates the effect of BMPs at the field and watershed scales. At the field-scale, the most effective single practice at reducing sediment, TP, and DRP is no-tillage followed by cover crops (CC); CC are the most effective single practice at reducing nitrate. The most effective BMP combinations include filter strips, which can have a sizable effect on reducing sediment and phosphorus loads. At the watershed scale, model results indicate current NCP BMPs result in minimal sediment and nutrient reductions (<10%).

Effects of horizontal grid resolution on evapotranspiration partitioning using TerrSysMP

NASA Astrophysics Data System (ADS)

Shrestha, P.; Sulis, M.; Simmer, C.; Kollet, S.

2018-02-01

Biotic leaf transpiration (T) and abiotic evaporation (E) are the two major pathways by which water is transferred from land surfaces to the atmosphere. Earth system models simulating the terrestrial water, carbon and energy cycle are required to reliably embed the role of soil and vegetation processes in order to realistically reproduce both fluxes including their relative contributions to total evapotranspiration (ET). Earth system models are also being used with increasing spatial resolutions to better simulate the effects of surface heterogeneity on the regional water and energy cycle and to realistically include effects of subsurface lateral flow paths, which are expected to feed back on the exchange fluxes and their partitioning in the model. Using the hydrological component of the Terrestrial Systems Modeling Platform (TerrSysMP), we examine the uncertainty in the estimates of T/ET ratio due to horizontal model grid resolution for a dry and wet year in the Inde catchment (western Germany). The aggregation of topography results in smoothing of slope magnitudes and the filtering of small-scale convergence and divergence zones, which directly impacts the surface-subsurface flow. Coarsening of the grid resolution from 120 m to 960 m increased the available soil moisture for ground evaporation, and decreased T/ET ratio by about 5% and 8% for dry and wet year respectively. The change in T/ET ratio was more pronounced for agricultural crops compared to forested areas, indicating a strong local control of vegetation on the ground evaporation, affecting the domain average statistics.

Efficient infiltration of water in the subsurface by using point-wells: A field study

NASA Astrophysics Data System (ADS)

Lopik, J. V.; Schotting, R.; Raoof, A.

2017-12-01

The ability to infiltrate large volumes of water in the subsurface would have great value for battling flooding in urban regions. Moreover, efficient water infiltration is key to optimize underground aquifer storage and recovery (ASR), aquifer thermal energy storage (ATES), as well as construction dewatering systems. Usually, variable infiltration rates of large water quantities could have a huge hydrogeological impact in the upper part of (phreatic) aquifer systems. In urban regions, minimizing excessive groundwater table fluctuations are necessary. A newly developed method, Fast, High Volume Infiltration (FHVI), by Dutch dewatering companies can be used to enable fast injection into the shallow subsurface. Conventional infiltration methods are using injection wells that screen large parts of the aquifer depth, whereas FHVI uses a specific infiltration point (1-m well screen) in the aquifer. These infiltration points are generally thin, high permeable layers in the aquifer of approximately 0.5-2 meter thick, and are embedded by less permeable layers. Currently, much higher infiltration pressures in shallow aquifers can be achieved with FHVI (up to 1 bar) compared to conventional infiltration methods ( 0.2 bar). Despite the high infiltration pressures and high discharge rate near the FHVI-filter, the stresses on shallow groundwater levels are significantly reduced with FHVI. In order to investigate the mechanisms that enable FHVI, a field experiment is conducted in a sandy aquifer to obtain insight in the 3-D hydraulic pressure distribution and flow patterns around a FHVI-filter during infiltration. A detailed characterization of the soil profile is obtained by using soil samples and cone pressure tests with a specific hydraulic profiling tool to track the vertical variation in aquifer permeability. A tracer test with bromide and heat is conducted to investigate preferential flow paths. The experimental data show that tracking small heterogeneities in aquifers and analysing the permeability difference ratio between the aimed infiltration layer and the surrounding layers in the aquifer are key to optimize the configuration of the FHVI-well. The results show that the use of point wells in thin, high permeable layers could drastically improve the efficiency of the infiltration system.

A screening test for capsaicin-stimulated salivary flow using filter paper: a study for diagnosis of hyposalivation with a complaint of dry mouth.

PubMed

Kanehira, Takashi; Yamaguchi, Tomotaka; Asano, Kozo; Morita, Manabu; Maeshima, Etsuko; Matsuda, Akemi; Fujii, Yoshihiro; Sakamoto, Wataru

2011-07-01

The purpose of this study was to develop a simple screening technique for diagnosis of hyposalivation with dry mouth by estimation of capsaicin-stimulated salivary flow using filter paper. An assay system comprising 5 spots containing starch and potassium iodide on filter paper incorporating or without capsaicin and a coloring reagent was designed. We investigated whether the number of colored spots using the filter paper incorporating capsaicin could distinguish between healthy subjects and subjects with hyposalivation and dry mouth. In the healthy group (>200 μL/min; n = 33), the capsaicin-stimulated salivary flow significantly increased as compared with the resting salivary flow, from 1.2 ± 1.4 to 2.9 ± 1.3 colored spots (P < .05). In contrast, the hyposalivation group with dry mouth (<100 μL/min; n = 32) hardly changed (4.4 ± 1.0 vs 4.9 ± 0.2), except for 3 subjects who had considerable elevated secretion on capsaicin stimulation. By measuring resting and stimulated salivary flows, this method should be useful for evaluating retained functional ability of salivary glands and screening of hyposalivation with dry mouth. Copyright © 2011 Mosby, Inc. All rights reserved.

Designing Adaptive Low Dissipative High Order Schemes

NASA Technical Reports Server (NTRS)

Yee, H. C.; Sjoegreen, B.; Parks, John W. (Technical Monitor)

2002-01-01

Proper control of the numerical dissipation/filter to accurately resolve all relevant multiscales of complex flow problems while still maintaining nonlinear stability and efficiency for long-time numerical integrations poses a great challenge to the design of numerical methods. The required type and amount of numerical dissipation/filter are not only physical problem dependent, but also vary from one flow region to another. This is particularly true for unsteady high-speed shock/shear/boundary-layer/turbulence/acoustics interactions and/or combustion problems since the dynamics of the nonlinear effect of these flows are not well-understood. Even with extensive grid refinement, it is of paramount importance to have proper control on the type and amount of numerical dissipation/filter in regions where it is needed.

Assessment of intermittently loaded woodchip and sand filters to treat dairy soiled water.

PubMed

Murnane, J G; Brennan, R B; Healy, M G; Fenton, O

2016-10-15

Land application of dairy soiled water (DSW) is expensive relative to its nutrient replacement value. The use of aerobic filters is an effective alternative method of treatment and potentially allows the final effluent to be reused on the farm. Knowledge gaps exist concerning the optimal design and operation of filters for the treatment of DSW. To address this, 18 laboratory-scale filters, with depths of either 0.6 m or 1 m, were intermittently loaded with DSW over periods of up to 220 days to evaluate the impacts of depth (0.6 m versus 1 m), organic loading rates (OLRs) (50 versus 155 g COD m(-2) d(-1)), and media type (woodchip versus sand) on organic, nutrient and suspended solids (SS) removals. The study found that media depth was important in contaminant removal in woodchip filters. Reductions of 78% chemical oxygen demand (COD), 95% SS, 85% total nitrogen (TN), 82% ammonium-nitrogen (NH4N), 50% total phosphorus (TP), and 54% dissolved reactive phosphorus (DRP) were measured in 1 m deep woodchip filters, which was greater than the reductions in 0.6 m deep woodchip filters. Woodchip filters also performed optimally when loaded at a high OLR (155 g COD m(-2) d(-1)), although the removal mechanism was primarily physical (i.e. straining) as opposed to biological. When operated at the same OLR and when of the same depth, the sand filters had better COD removals (96%) than woodchip (74%), but there was no significant difference between them in the removal of SS and NH4N. However, the likelihood of clogging makes sand filters less desirable than woodchip filters. Using the optimal designs of both configurations, the filter area required per cow for a woodchip filter is more than four times less than for a sand filter. Therefore, this study found that woodchip filters are more economically and environmentally effective in the treatment of DSW than sand filters, and optimal performance may be achieved using woodchip filters with a depth of at least 1 m, operated at an OLR of 155 g COD m(-2) d(-1). Copyright © 2016 Elsevier Ltd. All rights reserved.

Assessment of zero-equation SGS models for simulating indoor environment

NASA Astrophysics Data System (ADS)

Taghinia, Javad; Rahman, Md Mizanur; Tse, Tim K. T.

2016-12-01

The understanding of air-flow in enclosed spaces plays a key role to designing ventilation systems and indoor environment. The computational fluid dynamics aspects dictate that the large eddy simulation (LES) offers a subtle means to analyze complex flows with recirculation and streamline curvature effects, providing more robust and accurate details than those of Reynolds-averaged Navier-Stokes simulations. This work assesses the performance of two zero-equation sub-grid scale models: the Rahman-Agarwal-Siikonen-Taghinia (RAST) model with a single grid-filter and the dynamic Smagorinsky model with grid-filter and test-filter scales. This in turn allows a cross-comparison of the effect of two different LES methods in simulating indoor air-flows with forced and mixed (natural + forced) convection. A better performance against experiments is indicated with the RAST model in wall-bounded non-equilibrium indoor air-flows; this is due to its sensitivity toward both the shear and vorticity parameters.

Modeling of Mixing Behavior in a Combined Blowing Steelmaking Converter with a Filter-Based Euler-Lagrange Model

NASA Astrophysics Data System (ADS)

Li, Mingming; Li, Lin; Li, Qiang; Zou, Zongshu

2018-05-01

A filter-based Euler-Lagrange multiphase flow model is used to study the mixing behavior in a combined blowing steelmaking converter. The Euler-based volume of fluid approach is employed to simulate the top blowing, while the Lagrange-based discrete phase model that embeds the local volume change of rising bubbles for the bottom blowing. A filter-based turbulence method based on the local meshing resolution is proposed aiming to improve the modeling of turbulent eddy viscosities. The model validity is verified through comparison with physical experiments in terms of mixing curves and mixing times. The effects of the bottom gas flow rate on bath flow and mixing behavior are investigated and the inherent reasons for the mixing result are clarified in terms of the characteristics of bottom-blowing plumes, the interaction between plumes and top-blowing jets, and the change of bath flow structure.

Estimating the soil moisture profile by assimilating near-surface observations with the ensemble Kalman filter (EnKF)

NASA Astrophysics Data System (ADS)

Zhang, Shuwen; Li, Haorui; Zhang, Weidong; Qiu, Chongjian; Li, Xin

2005-11-01

The paper investigates the ability to retrieve the true soil moisture profile by assimilating near-surface soil moisture into a soil moisture model with an ensemble Kaiman filter (EnKF) assimilation scheme, including the effect of ensemble size, update interval and nonlinearities in the profile retrieval, the required time for full retrieval of the soil moisture profiles, and the possible influence of the depth of the soil moisture observation. These questions are addressed by a desktop study using synthetic data. The “true” soil moisture profiles are generated from the soil moisture model under the boundary condition of 0.5 cm d-1 evaporation. To test the assimilation schemes, the model is initialized with a poor initial guess of the soil moisture profile, and different ensemble sizes are tested showing that an ensemble of 40 members is enough to represent the covariance of the model forecasts. Also compared are the results with those from the direct insertion assimilation scheme, showing that the EnKF is superior to the direct insertion assimilation scheme, for hourly observations, with retrieval of the soil moisture profile being achieved in 16 h as compared to 12 days or more. For daily observations, the true soil moisture profile is achieved in about 15 days with the EnKF, but it is impossible to approximate the true moisture within 18 days by using direct insertion. It is also found that observation depth does not have a significant effect on profile retrieval time for the EnKF. The nonlinearities have some negative influence on the optimal estimates of soil moisture profile but not very seriously.

Short-term effects of sugarcane waste products from ethanol production plant as soil amendments on sugarcane growth and metal stabilization.

PubMed

Akkajit, Pensiri; DeSutter, Thomas; Tongcumpou, Chantra

2013-05-01

Numerous waste products have been widely studied and used as soil amendments and metal immobilizing agents. Waste utilization from ethanol production processes as soil amendments is one of the most promising and sustainable options to help utilize materials effectively, reduce waste disposal, and add value to byproducts. As a consequence, this present work carried out a four-month pot experiment of sugarcane (Saccharum officinarum L.) cultivation in Cd and Zn contaminated soil to determine the effect of three sugarcane waste products (boiler ash, filter cake and vinasse) as soil amendment on sugarcane growth, metal translocation and accumulation in sugarcane, and fractionation of Cd and Zn in soil by the BCR sequential extraction. Four treatments were tested: (1) non-amended soil; (2) 3% w/w boiler ash; (3) 3% w/w filter cake; and (4) a combination of 1.5% boiler ash and 1.5% vinasse (w/w). Our findings showed the improved biomass production of sugarcanes; 6 and 3-fold higher for the above ground parts (from 8.5 to 57.6 g per plant) and root (from 2.1 to 6.59 g per plant), respectively, as compared to non-amended soil. Although there was no significant difference in Cd and Zn uptake in sugarcane (mg kg(-1)) between the non-amended soil and the treated soils (0.44 to 0.52 mg Cd kg(-1) and 39.9 to 48.1 mg Zn kg(-1), respectively), the reduction of the most bioavailable Cd concentration (BCR1 + 2) in the treated soils (35.4-54.5%) and the transformation of metal into an insoluble fraction (BCR3) highlighted the beneficial effects of sugarcane waste-products in promoting the sugarcane growth and Cd stabilization in soil.

Separation of particulate from flue gas of fossil fuel combustion and gasification

DOEpatents

Yang, W.C.; Newby, R.A.; Lippert, T.E.

1997-08-05

The gas from combustion or gasification of fossil fuel contains fly ash and other particulates. The fly ash is separated from the gas in a plurality of standleg moving granular-bed filter modules. Each module includes a dipleg through which the bed media flows into the standleg. The bed media forms a first filter bed having an upper mass having a first frusto-conical surface in a frusto-conical member at the entrance to the standleg and a lower mass having a second frusto-conical surface of substantially greater area than the first surface after it passes through the standleg. A second filter media bed may be formed above the first filter media bed. The gas is fed tangentially into the module above the first surface. The fly ash is captured on the first frusto-conical surface and within the bed mass. The processed gas flows out through the second frusto-conical surface and then through the second filter bed, if present. The bed media is cleaned of the captured fly ash and recirculated to the moving granular bed filter. Alternatively, the bed media may be composed of the ash from the combustion which is pelletized to form agglomerates. The ash flows through the bed only once; it is not recycled. 11 figs.

Separation of particulate from flue gas of fossil fuel combustion and gasification

DOEpatents

Yang, Wen-Ching; Newby, Richard A.; Lippert, Thomas E.

1997-01-01

The gas from combustion or gasification of fossil fuel contains flyash and other particulate. The flyash is separated from the gas in a plurality of standleg moving granular-bed filter modules. Each module includes a dipleg through which the bed media flows into the standleg. The bed media forms a first filter bed having an upper mass having a first frusto-conical surface in a frusto-conical member at the entrance to the standleg and a lower mass having a second frusto-conical surface of substantially greater area than the first surface after it passes through the standleg. A second filter media bed may be formed above the first filter media bed. The gas is fed tangentially into the module above the first surface. The flyash is captured on the first frusto-conical surface and within the bed mass. The processed gas flows out through the second frusto-conical surface and then through the second filter bed, if present. The bed media is cleaned of the captured flyash and recirculated to the moving granular bed filter. Alternatively, the bed media may be composed of the ash from the combustion which is pelletized to form agglomerates. The ash flows through the bed only once; it is not recycled.

Nitrate and phosphate removal from agricultural subsurface drainage using laboratory woodchip bioreactors and recycled steel byproduct filters.

PubMed

Hua, Guanghui; Salo, Morgan W; Schmit, Christopher G; Hay, Christopher H

2016-10-01

Woodchip bioreactors have been increasingly used as an edge-of-field treatment technology to reduce the nitrate loadings to surface waters from agricultural subsurface drainage. Recent studies have shown that subsurface drainage can also contribute substantially to the loss of phosphate from agricultural soils. The objective of this study was to investigate nitrate and phosphate removal in subsurface drainage using laboratory woodchip bioreactors and recycled steel byproduct filters. The woodchip bioreactor demonstrated average nitrate removal efficiencies of 53.5-100% and removal rates of 10.1-21.6 g N/m(3)/d for an influent concentration of 20 mg N/L and hydraulic retention times (HRTs) of 6-24 h. When the influent nitrate concentration increased to 50 mg N/L, the bioreactor nitrate removal efficiency and rate averaged 75% and 18.9 g N/m(3)/d at an HRT of 24 h. Nitrate removal by the woodchips followed zero-order kinetics with rate constants of 1.42-1.80 mg N/L/h when nitrate was non-limiting. The steel byproduct filter effectively removed phosphate in the bioreactor effluent and the total phosphate adsorption capacity was 3.70 mg P/g under continuous flow conditions. Nitrite accumulation occurred in the woodchip bioreactor and the effluent nitrite concentrations increased with decreasing HRTs and increasing influent nitrate concentrations. The steel byproduct filter efficiently reduced the level of nitrite in the bioreactor effluent. Overall, the results of this study suggest that woodchip denitrification followed by steel byproduct filtration is an effective treatment technology for nitrate and phosphate removal in subsurface drainage. Published by Elsevier Ltd.

Evaluation of diffuse and preferential flow pathways of infiltratedprecipitation and irrigation using oxygen and hydrogen isotopes

USGS Publications Warehouse

Ma, Bin; Liang, Xing; Liu, Shaohua; Jin, Menggui; Nimmo, John R.; Li, Jingxin

2017-01-01

Subsurface-water flow pathways in three different land-use areas (non-irrigated grassland, poplar forest, and irrigated arable land) in the central North China Plain were investigated using oxygen (18O) and hydrogen (2H) isotopes in samples of precipitation, soils, and groundwater. Soil water in the top 10 cm was significantly affected by both evaporation and infiltration. Water at 10–40 cm depth in the grassland and arable land, and 10–60 cm in poplar forest, showed a relatively short residence time, as a substantial proportion of antecedent soil water was mixed with a 92-mm storm infiltration event, whereas below those depths (down to 150 cm), depleted δ18O spikes suggested that some storm water bypassed the shallow soil layers. Significant differences, in soil-water content and δ18O values, within a small area, suggested that the proportion of immobile soil water and water flowing in subsurface pathways varies depending on local vegetation cover, soil characteristics and irrigation applications. Soil-water δ18O values revealed that preferential flow and diffuse flow coexist. Preferential flow was active within the root zone, independent of antecedent soil-water content, in both poplar forest and arable land, whereas diffuse flow was observed in grassland. The depleted δ18O spikes at 20–50 cm depth in the arable land suggested the infiltration of irrigation water during the dry season. Temporal isotopic variations in precipitation were subdued in the shallow groundwater, suggesting more complete mixing of different input waters in the unsaturated zone before reaching the shallow groundwater.

Hydrologic flow path development varies by aspect during spring snowmelt in complex subalpine terrain

NASA Astrophysics Data System (ADS)

Webb, Ryan W.; Fassnacht, Steven R.; Gooseff, Michael N.

2018-01-01

In many mountainous regions around the world, snow and soil moisture are key components of the hydrologic cycle. Preferential flow paths of snowmelt water through snow have been known to occur for years with few studies observing the effect on soil moisture. In this study, statistical analysis of the topographical and hydrological controls on the spatiotemporal variability of snow water equivalent (SWE) and soil moisture during snowmelt was undertaken at a subalpine forested setting with north, south, and flat aspects as a seasonally persistent snowpack melts. We investigated if evidence of preferential flow paths in snow can be observed and the effect on soil moisture through measurements of snow water equivalent and near-surface soil moisture, observing how SWE and near-surface soil moisture vary on hillslopes relative to the toes of hillslopes and flat areas. We then compared snowmelt infiltration beyond the near-surface soil between flat and sloping terrain during the entire snowmelt season using soil moisture sensor profiles. This study was conducted during varying snowmelt seasons representing above-normal, relatively normal, and below-normal snow seasons in northern Colorado. Evidence is presented of preferential meltwater flow paths at the snow-soil interface on the north-facing slope causing increases in SWE downslope and less infiltration into the soil at 20 cm depth; less association is observed in the near-surface soil moisture (top 7 cm). We present a conceptualization of the meltwater flow paths that develop based on slope aspect and soil properties. The resulting flow paths are shown to divert at least 4 % of snowmelt laterally, accumulating along the length of the slope, to increase the snow water equivalent by as much as 170 % at the base of a north-facing hillslope. Results from this study show that snow acts as an extension of the vadose zone during spring snowmelt and future hydrologic investigations will benefit from studying the snow and soil together.

Remotely serviced filter and housing

DOEpatents

Ross, Maurice J.; Zaladonis, Larry A.

1988-09-27

A filter system for a hot cell comprises a housing adapted for input of air or other gas to be filtered, flow of the air through a filter element, and exit of filtered air. The housing is tapered at the top to make it easy to insert a filter cartridge using an overhead crane. The filter cartridge holds the filter element while the air or other gas is passed through the filter element. Captive bolts in trunnion nuts are readily operated by electromechanical manipulators operating power wrenches to secure and release the filter cartridge. The filter cartridge is adapted to make it easy to change a filter element by using a master-slave manipulator at a shielded window station.

Improving Simulated Soil Moisture Fields Through Assimilation of AMSR-E Soil Moisture Retrievals with an Ensemble Kalman Filter and a Mass Conservation Constraint

NASA Technical Reports Server (NTRS)

Li, Bailing; Toll, David; Zhan, Xiwu; Cosgrove, Brian

2011-01-01

Model simulated soil moisture fields are often biased due to errors in input parameters and deficiencies in model physics. Satellite derived soil moisture estimates, if retrieved appropriately, represent the spatial mean of soil moisture in a footprint area, and can be used to reduce model bias (at locations near the surface) through data assimilation techniques. While assimilating the retrievals can reduce model bias, it can also destroy the mass balance enforced by the model governing equation because water is removed from or added to the soil by the assimilation algorithm. In addition, studies have shown that assimilation of surface observations can adversely impact soil moisture estimates in the lower soil layers due to imperfect model physics, even though the bias near the surface is decreased. In this study, an ensemble Kalman filter (EnKF) with a mass conservation updating scheme was developed to assimilate the actual value of Advanced Microwave Scanning Radiometer (AMSR-E) soil moisture retrievals to improve the mean of simulated soil moisture fields by the Noah land surface model. Assimilation results using the conventional and the mass conservation updating scheme in the Little Washita watershed of Oklahoma showed that, while both updating schemes reduced the bias in the shallow root zone, the mass conservation scheme provided better estimates in the deeper profile. The mass conservation scheme also yielded physically consistent estimates of fluxes and maintained the water budget. Impacts of model physics on the assimilation results are discussed.

The Cacti microbiome: interplay between habitat-filtering and host-specificity

USDA-ARS?s Scientific Manuscript database

The main focus of this research was to generate an holistic baseline of the associations Cacti establish with prokaryotes and fungi in the bulk and proximal soil (the soils), the rhizosphere and the phyllosphere (the episphere), as well as in the root and stem endosphere (the endosphere) through phy...

The potential of 2D Kalman filtering for soil moisture data assimilation

USDA-ARS?s Scientific Manuscript database

We examine the potential for parameterizing a two-dimensional (2D) land data assimilation system using spatial error auto-correlation statistics gleaned from a triple collocation analysis and the triplet of: (1) active microwave-, (2) passive microwave- and (3) land surface model-based surface soil ...

Mapping Soil Surface Macropores Using Infrared Thermography: An Exploratory Laboratory Study

PubMed Central

de Lima, João L. M. P.; Abrantes, João R. C. B.; Silva, Valdemir P.; de Lima, M. Isabel P.; Montenegro, Abelardo A. A.

2014-01-01

Macropores and water flow in soils and substrates are complex and are related to topics like preferential flow, nonequilibrium flow, and dual-continuum. Hence, the quantification of the number of macropores and the determination of their geometry are expected to provide a better understanding on the effects of pores on the soil's physical and hydraulic properties. This exploratory study aimed at evaluating the potential of using infrared thermography for mapping macroporosity at the soil surface and estimating the number and size of such macropores. The presented technique was applied to a small scale study (laboratory soil flume). PMID:25371915

Filtration device for rapid separation of biological particles from complex matrices

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Sangil; Naraghi-Arani, Pejman; Liou, Megan

2018-01-09

Methods and systems for filtering of biological particles are disclosed. Filtering membranes separate adjacent chambers. Through osmotic or electrokinetic processes, flow of particles is carried out through the filtering membranes. Cells, viruses and cell waste can be filtered depending on the size of the pores of the membrane. A polymer brush can be applied to a surface of the membrane to enhance filtering and prevent fouling.

A priori and a posteriori investigations for developing large eddy simulations of multi-species turbulent mixing under high-pressure conditions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Borghesi, Giulio; Bellan, Josette, E-mail: josette.bellan@jpl.nasa.gov; Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California 91109-8099

2015-03-15

A Direct Numerical Simulation (DNS) database was created representing mixing of species under high-pressure conditions. The configuration considered is that of a temporally evolving mixing layer. The database was examined and analyzed for the purpose of modeling some of the unclosed terms that appear in the Large Eddy Simulation (LES) equations. Several metrics are used to understand the LES modeling requirements. First, a statistical analysis of the DNS-database large-scale flow structures was performed to provide a metric for probing the accuracy of the proposed LES models as the flow fields obtained from accurate LESs should contain structures of morphology statisticallymore » similar to those observed in the filtered-and-coarsened DNS (FC-DNS) fields. To characterize the morphology of the large-scales structures, the Minkowski functionals of the iso-surfaces were evaluated for two different fields: the second-invariant of the rate of deformation tensor and the irreversible entropy production rate. To remove the presence of the small flow scales, both of these fields were computed using the FC-DNS solutions. It was found that the large-scale structures of the irreversible entropy production rate exhibit higher morphological complexity than those of the second invariant of the rate of deformation tensor, indicating that the burden of modeling will be on recovering the thermodynamic fields. Second, to evaluate the physical effects which must be modeled at the subfilter scale, an a priori analysis was conducted. This a priori analysis, conducted in the coarse-grid LES regime, revealed that standard closures for the filtered pressure, the filtered heat flux, and the filtered species mass fluxes, in which a filtered function of a variable is equal to the function of the filtered variable, may no longer be valid for the high-pressure flows considered in this study. The terms requiring modeling are the filtered pressure, the filtered heat flux, the filtered pressure work, and the filtered species mass fluxes. Improved models were developed based on a scale-similarity approach and were found to perform considerably better than the classical ones. These improved models were also assessed in an a posteriori study. Different combinations of the standard models and the improved ones were tested. At the relatively small Reynolds numbers achievable in DNS and at the relatively small filter widths used here, the standard models for the filtered pressure, the filtered heat flux, and the filtered species fluxes were found to yield accurate results for the morphology of the large-scale structures present in the flow. Analysis of the temporal evolution of several volume-averaged quantities representative of the mixing layer growth, and of the cross-stream variation of homogeneous-plane averages and second-order correlations, as well as of visualizations, indicated that the models performed equivalently for the conditions of the simulations. The expectation is that at the much larger Reynolds numbers and much larger filter widths used in practical applications, the improved models will have much more accurate performance than the standard one.« less

Miscellaneous methods for measuring matric or water potential

USGS Publications Warehouse

Scanlon, Bridget R.; Andraski, Brian J.; Bilskie, Jim; Dane, Jacob H.; Topp, G. Clarke

2002-01-01

A variety of techniques to measure matric potential or water potential in the laboratory and in the field are described in this section. The techniques described herein require equilibration of some medium whose matric or water potential can be determined from previous calibration or can be measured directly. Under equilibrium conditions the matric or water potential of the medium is equal to that of the soil. The techniques can be divided into: (i) those that measure matric potential and (ii) those that measure water potential (sum of matric and osmotic potentials). Matric potential is determined when the sensor matrix is in direct contact with the soil, so salts are free to diffuse in or out of the sensor matrix, and the equilibrium measurement therefore reflects matric forces acting on the water. Water potential is determined when the sensor is separated from the soil by a vapor gap, so salts are not free to move in or out of the sensor, and the equilibrium measurement reflects the sum of the matric and osmotic forces acting on the water.Seven different techniques are described in this section. Those that measure matric potential include (i) heat dissipation sensors, (ii) electrical resistance sensors, (iii) frequency domain and time domain sensors, and (iv) electro-optical switches. A method that can be used to measure matric potential or water potential is the (v) filter paper method. Techniques that measure water potential include (vi) the Dew Point Potentiameter (Decagon Devices, Inc., Pullman, WA1) (water activity meter) and (vii) vapor equilibration.The first four techniques are electronically based methods for measuring matric potential. Heat dissipation sensors and electrical resistance sensors infer matric potential from previously determined calibration relations between sensor heat dissipation or electrical resistance and matric potential. Frequency-domain and timedomain matric potential sensors measure water content, which is related to matric potential of the sensor through calibration. Electro-optical switches measure changes in light transmission through thin, nylon filters as they absorb or desorb water in response to changes in matric potential. Heat dissipation sensors and electrical resistance sensors are used primarily in the field to provide information on matric potential. Frequency domain matric potential sensors are new and have not been widely used. Time domain matric potential sensors and electro-optical switches are new and have not been commercialized. For the fifth technique, filter paper is used as the standard matrix. The filter paper technique measures matric potential when the filter paper is in direct contact with soil or water potential when separated from soil by a vapor gap. The Dew Point Potentiameter calculates water potential from the measured dew point and sample temperature. The vapor equilibration technique involves equilibration of soil samples with salt solutions of known osmotic potential. The filter paper, Dew Point Potentiameter, and vapor equilibration techniques are generally used in the laboratory to measure water potential of disturbed field samples or to measure water potential for water retention functions.

Efficiency of several micro-fiber glass filters for recovery of poliovirus from tape water.

PubMed Central

Payment, P; Trudel, M

1979-01-01

Micro-fiber glass filters from Gelman, Filterite, Johns-Manville, and Whatman were compared with Millipore membrane filters on the basis of their virus adsorbancy, flow rate, clogging resistance, and virus concentration efficiency by using tap water at 2 nephelometric turbidity units. As virus adsorbants the Johns-Manville D39, Filterite 0.25-micron, Filterite 0.45-micron, and Millipore 0.45-micron filters were the most efficient, retaining more than 99% of the added virus in water at pH 3.5 and 0.0005 M aluminum chloride. The Johns-Manville D79 and D49 filters retained 92 and 96% of the virus, respectively, whereas the Whatman GF-D, Whatman GF-F, Gelman A-E, and Millipore AP-20 filters retained only 28, 78, 56, and 34% of the virus, respectively. The best flow rate and clogging resistance were obtained with the Johns-Manville D79 filter or with this filter acting as a prefilter to the Johns-Manville D49, Johns-Manville D39, or Filterite 0.45-micron filter. Finally, poliovirus experimentally seeded in 20 liters of tape water was recovered from Johns-Manville D79-Johns-Manville D39 or Johns-Manville D79-Filterite 0.45 micron 142-mm filter combinations was a efficiencies of 86 and 85%, respectively. PMID:231414

A Study of the Time Dependence in Fracture Processes Relating to Service Life Prediction of Adhesive Joints and Advanced Composites.

DTIC Science & Technology

1981-04-30

fluid temperature should exceed 145°F. The flow control module contains all the hydraulic circuit elements necessary for both the pressure line to and...are contained in three basic modules : 1) the hydraulic power supply, 2) a flow control module containing valving, accumulators and filters, and 3) the...hydraulic transient overpressures, is located in the flow control module , as are the high and low pressure filters. The load frame (MTS Systems Corp

Shuttle filter study. Volume 3: Appendix

NASA Technical Reports Server (NTRS)

1974-01-01

Test data obtained from flow resistance and contaminant tolerance tests on the various porous media evaluated in the different fluids are presented in both graphical and tabular forms. Test procedures for both flow resistance and contaminant tolerance testing are presented, and the development of a system for continuously adding contaminant at a predetermined rate to a flowing fluid stream is described. Also included is a section describing the development effort of the self-indexing filter. This concept was adapted during this program for various shuttle applications.

Groundwater Flow Through a Constructed Treatment Wetland

DTIC Science & Technology

2002-03-01

sediments or has the water found preferential flow paths? (2) Does the behavior of groundwater flow change with varying loading rates or environmental...surface of the wetland. Water flows through a subsurface flow wetland in a similar fashion as groundwater flows through an aquifer. The concept is...circuiting of the wetland media. Groundwater Flow Various physical properties influence the flow of water through soil. In wetlands, the type of soil

Natural microbial populations in a water-based biowaste management system for space life support

NASA Astrophysics Data System (ADS)

Bornemann, Gerhild; Waßer, Kai; Tonat, Tim; Moeller, Ralf; Bohmeier, Maria; Hauslage, Jens

2015-11-01

The reutilization of wastewater is a key issue with regard to long-term space missions and planetary habitation. This study reports the design, test runs and microbiological analyses of a fixed bed biofiltration system which applies pumice grain (16-25 mm grain size, 90 m2 /m3 active surface) as matrix and calcium carbonate as buffer. For activation, the pumice was inoculated with garden soil known to contain a diverse community of microorganisms, thus enabling the filtration system to potentially degrade all kinds of organic matter. Current experiments over 194 days with diluted synthetic urine (7% and 20%) showed that the 7% filter units produced nitrate slowly but steadily (max. 2191 mg NO3-N/day). In the 20% units nitrate production was slower and less stable (max. 1411 mg NO3-N/day). 84% and 76% of the contained nitrogen was converted into nitrate. The low conversion rate is assumed to be due to the high flow rate, which keeps the biofilm on the pumice thin. At the same time the thin biofilm seems to prevent the activity of denitrifiers implicating the existence of a trade off between rate and the amount of nitrogen loss. Microbiological analyses identified a comparatively low number of species (26 in the filter material, 12 in the filtrate) indicating that urine serves as a strongly selective medium and filter units for the degradation of mixed feedstock have to be pre-conditioned on the intended substrates from the beginning.

Assessment of addition of biochar to filtering mixtures for potential water pollutant removal.

PubMed

Piscitelli, Lea; Rivier, Pierre-Adrien; Mondelli, Donato; Miano, Teodoro; Joner, Erik J

2018-01-01

Green roofs are used increasingly to alleviate peaks of water discharge into the sewage systems in urban areas. Surface runoff from roofs contain pollutants from dry and wet deposition, and green roofs offer a possibility to reduce the amounts of pollutants in the water discharged from roofs by degradation and filtering. These pollutants would otherwise enter wastewater treatments plants and ultimately end up in sewage sludge that is spread on agricultural soils. The most common substrates used in green roofs have limited capacity for filtration and sorption. Also, more sustainable alternatives are sought, due to the high carbon footprint of these materials. Biochar is a carbon-rich material produced by pyrolysis of biomass, and several types of biochar have been described as good sorbents and filter materials. Biochar is also a light and carbon negative material, which may fulfill other desired criteria for new green roof substrates. We here report on an experiment where two types of biochar, produced from olive husks at 450 °C or from forest waste at 850 ° C were mixed with volcanic rock or peat, and tested for retention capacity of phenanthrene and six heavy metals in a column experiment with unsaturated gravimetric water flow lasting for 3 weeks. The results suggest that biochar as a component in green roof substrates perform better than traditional materials, concerning retention of the tested pollutants, and that different types of biochar have different properties in this respect.

Carbon black retention in saturated natural soils: Effects of flow conditions, soil surface roughness and soil organic matter.

PubMed

Lohwacharin, J; Takizawa, S; Punyapalakul, P

2015-10-01

We evaluated factors affecting the transport, retention, and re-entrainment of carbon black nanoparticles (nCBs) in two saturated natural soils under different flow conditions and input concentrations using the two-site transport model and Kelvin probe force microscopy (KPFM). Soil organic matter (SOM) was found to create unfavorable conditions for the retention. Despite an increased flow velocity, the relative stability of the estimated maximum retention capacity in soils may suggest that flow-induced shear stress forces were insufficient to detach nCB. The KPFM observation revealed that nCBs were retained at the grain boundary and on surface roughness, which brought about substantial discrepancy between theoretically-derived attachment efficiency factors and the ones obtained by the experiments using the two-site transport model. Thus, decreasing ionic strength and increasing solution pH caused re-entrainment of only a small fraction of retained nCB in the soil columns. Copyright © 2015 Elsevier Ltd. All rights reserved.

Hot air injection for removal of dense, non-aqueous-phase liquid contaminants from low-permeability soils

DOE Office of Scientific and Technical Information (OSTI.GOV)

Payne, F.C.

1996-08-01

The performance of soil vapor extraction systems for the recovery of volatile and semi-volatile organic compounds is potentially enhanced by the injection of heated air to increase soil temperatures. The soil temperature increase is expected to improve soil vapor extraction (SVE) performance by increasing target compound vapor pressures and by increasing soil permeability through drying. The vapor pressure increase due to temperature rise relieves the vapor pressure limit on the feasibility of soil vapor extraction. However, the system still requires an air flow through the soil system to deliver heat and to recover mobilized contaminants. Although the soil permeability canmore » be increased through drying, very low permeability soils and low permeability soils adjacent to high permeability air flow pathways will be treated slowly, if at all. AR thermal enhancement methods face this limitation. Heated air injection offers advantages relative to other thermal techniques, including low capital and operation costs. Heated air injection is at a disadvantage relative to other thermal techniques due to the low heat capacity of air. To be effective, heated air injection requires that higher air flows be established than for steam injection or radio frequency heating. Heated air injection is not economically feasible for the stratified soil system developed as a standard test for this document. This is due to the inability to restrict heated air flow to the clay stratum when a low-resistance air flow pathway is available in the adjoining sand. However, the technology should be especially attractive, both technically and economically, for low-volatile contaminant recovery from relatively homogeneous soil formations. 16 refs., 2 tabs.« less

Temporal evolution of water repellency and preferential flow in the post-fire

NASA Astrophysics Data System (ADS)

Alanís, Nancy; Jordán, Antonio; Zavala, Lorena M.

2015-04-01

Forest fires usually intensify erosive process due to the reduction of vegetation cover and degradation of aggregation in the topsoil. Another common effect of wildifres is the development of soil water repellency, which in turn favors the formation of runoff, inhibiting or delaying infiltration. Under these conditions, infiltration occurs only when ponded water or runoff flow finds macropores and cracks in the soil surface, producing preferential flow pathways. When water infiltrates through these paths, a significant portion of the soil remains dry, limiting the supply of nutrients to the roots, favoring the rapid leaching of nutrients and agrochemicals, and other impacts on flora and hydrological processes at hillslope- or basin-scale. The existence of irregular wetting fronts has been observed frequently in burned or unburned water repellent soils. Although some authors have suggested that preferential flow paths may be more or less permanent in the case of unburned soils, the temporal evolution of preferential flow has been rarely studied in burned soils during the post-fire, after water repellency decreases or disappears. This research focuses on the temporal evolution of water repellency and preferential flows in an area affected by fire.

Effectiveness of cigarette filter tips for reducing cadmium in relation to other mainstream smoke constituents

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bache, C.A.; Lisk, D.J.; Shane, B.S.

The effectiveness of filter tips for reducing cadmium, tar, nicotine, carbon monoxide and carbon dioxide in cigarettes was studied. The cigarettes were made from tobacco grown on municipal sewage sludge-amended soil and were therefore high in cadmium. When machine-smoked, filter tips did not result in a significant reduction of cadmium deposited on Cambridge filters. This may indicate that a considerable fraction of cadmium is present in the vapor phase of the smoke and therefore not reduced to the same extent as the tar by certain filters. Nicotine and carbon monoxide were reduced to a lesser extent than tar. This indicatesmore » that the filter tip has influenced the combustion of the tobacco column during smoking.« less

The principle of ‘maximum energy dissipation’: a novel thermodynamic perspective on rapid water flow in connected soil structures

PubMed Central

Zehe, Erwin; Blume, Theresa; Blöschl, Günter

2010-01-01

Preferential flow in biological soil structures is of key importance for infiltration and soil water flow at a range of scales. In the present study, we treat soil water flow as a dissipative process in an open non-equilibrium thermodynamic system, to better understand this key process. We define the chemical potential and Helmholtz free energy based on soil physical quantities, parametrize a physically based hydrological model based on field data and simulate the evolution of Helmholtz free energy in a cohesive soil with different populations of worm burrows for a range of rainfall scenarios. The simulations suggest that flow in connected worm burrows allows a more efficient redistribution of water within the soil, which implies a more efficient dissipation of free energy/higher production of entropy. There is additional evidence that the spatial pattern of worm burrow density at the hillslope scale is a major control of energy dissipation. The pattern typically found in the study is more efficient in dissipating energy/producing entropy than other patterns. This is because upslope run-off accumulates and infiltrates via the worm burrows into the dry soil in the lower part of the hillslope, which results in an overall more efficient dissipation of free energy. PMID:20368256

Quantum dot transport in soil, plants, and insects.

PubMed

Al-Salim, Najeh; Barraclough, Emma; Burgess, Elisabeth; Clothier, Brent; Deurer, Markus; Green, Steve; Malone, Louise; Weir, Graham

2011-08-01

Environmental risk assessment of nanomaterials requires information not only on their toxicity to non-target organisms, but also on their potential exposure pathways. Here we report on the transport and fate of quantum dots (QDs) in the total environment: from soils, through their uptake into plants, to their passage through insects following ingestion. Our QDs are nanoparticles with an average particle size of 6.5 nm. Breakthrough curves obtained with CdTe/mercaptopropionic acid QDs applied to columns of top soil from a New Zealand organic apple orchard, a Hastings silt loam, showed there to be preferential flow through the soil's macropores. Yet the effluent recovery of QDs was just 60%, even after several pore volumes, indicating that about 40% of the influent QDs were filtered and retained by the soil column via some unknown exchange/adsorption/sequestration mechanism. Glycine-, mercaptosuccinic acid-, cysteine-, and amine-conjugated CdSe/ZnS QDs were visibly transported to a limited extent in the vasculature of ryegrass (Lolium perenne), onion (Allium cepa) and chrysanthemum (Chrysanthemum sp.) plants when cut stems were placed in aqueous QD solutions. However, they were not seen to be taken up at all by rooted whole plants of ryegrass, onion, or Arabidopsis thaliana placed in these solutions. Leafroller (Lepidoptera: Tortricidae) larvae fed with these QDs for two or four days, showed fluorescence along the entire gut, in their frass (larval feces), and, at a lower intensity, in their haemolymph. Fluorescent QDs were also observed and elevated cadmium levels detected inside the bodies of adult moths that had been fed QDs as larvae. These results suggest that exposure scenarios for QDs in the total environment could be quite complex and variable in each environmental domain. Copyright © 2011 Elsevier B.V. All rights reserved.

Characterization of a Regenerable Impactor Filter for Spacecraft Cabin Applications

NASA Technical Reports Server (NTRS)

Agui, Juan H.; Vijayakumar, R.

2015-01-01

Regenerable filters will play an important role in human exploration beyond low-Earth orbit. Life Support Systems aboard crewed spacecrafts will have to operate reliably and with little maintenance over periods of more than a year, even multiple years. Air filters are a key component of spacecraft life support systems, but they often require frequent routine maintenance. Bacterial filters aboard the International Space Station require almost weekly cleaning of the pre-filter screen to remove large lint debris captured in the microgravity environment. The source of the airborne matter which is collected on the filter screen is typically from clothing fibers, biological matter (hair, skin, nails, etc.) and material wear. Clearly a need for low maintenance filters requiring little to no crew intervention will be vital to the success of the mission. An impactor filter is being developed and tested to address this need. This filter captures large particle matter through inertial separation and impaction methods on collection surfaces, which can be automatically cleaned after they become heavily loaded. The impactor filter can serve as a pre-filter to augment the life of higher efficiency filters that capture fine and ultrafine particles. A prototype of the filter is being tested at the Particulate Filtration Laboratory at NASA Glenn Research Center to determine performance characteristics, including particle cut size and overall efficiency. Model results are presented for the flow characteristics near the orifice plate through which the particle-laden flow is accelerated as well as around the collection bands.

Fibrous filter efficiency and pressure drop in the viscous-inertial transition flow regime.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sanchez, Andres L.; Brockmann, John E.; Dellinger, Jennifer Gwynne

2011-10-01

Fibrous filter pressure drop and aerosol collection efficiency were measured at low air pressures (0.2 to 0.8 atm) and high face velocities (5 to 20 meters per second) to give fiber Reynolds numbers in the viscous-inertial transition flow regime (1 to 16). In this regime, contemporary filtration theory based on Kuwabara's viscous flow through an ensemble of fibers under-predicts single fiber impaction by several orders of magnitude. Streamline curvature increases substantially as inertial forces become dominant. Dimensionless pressure drop measurements followed the viscous-inertial theory of Robinson and Franklin rather than Darcy's linear pressure-velocity relationship (1972). Sodium chloride and iron nano-agglomeratemore » test aerosols were used to evaluate the effects of particle density and shape factor. Total filter efficiency collapsed when plotted against the particle Stokes and fiber Reynolds numbers. Efficiencies were then fitted with an impactor type equation where the cutpoint Stokes number and a steepness parameter described data well in the sharply increasing portion of the curve (20% to 80% efficiency). The cutpoint Stokes number was a linearly decreasing function of fiber Reynolds number. Single fiber efficiencies were calculated from total filter efficiencies and compared to contemporary viscous flow impaction theory (Stechkina et al. 1969), and numerical simulations from the literature. Existing theories under-predicted measured single fiber efficiencies although the assumption of uniform flow conditions for each successive layer of fibers is questionable; the common exponential relationship between single fiber efficiency and total filter efficiency may not be appropriate in this regime.« less

Spatial structure and scaling of macropores in hydrological process at small catchment scale

NASA Astrophysics Data System (ADS)

Silasari, Rasmiaditya; Broer, Martine; Blöschl, Günter

2013-04-01

During rainfall events, the formation of overland flow can occur under the circumstances of saturation excess and/or infiltration excess. These conditions are affected by the soil moisture state which represents the soil water content in micropores and macropores. Macropores act as pathway for the preferential flows and have been widely studied locally. However, very little is known about their spatial structure and conductivity of macropores and other flow characteristic at the catchment scale. This study will analyze these characteristics to better understand its importance in hydrological processes. The research will be conducted in Petzenkirchen Hydrological Open Air Laboratory (HOAL), a 64 ha catchment located 100 km west of Vienna. The land use is divided between arable land (87%), pasture (5%), forest (6%) and paved surfaces (2%). Video cameras will be installed on an agricultural field to monitor the overland flow pattern during rainfall events. A wireless soil moisture network is also installed within the monitored area. These field data will be combined to analyze the soil moisture state and the responding surface runoff occurrence. The variability of the macropores spatial structure of the observed area (field scale) then will be assessed based on the topography and soil data. Soil characteristics will be supported with laboratory experiments on soil matrix flow to obtain proper definitions of the spatial structure of macropores and its variability. A coupled physically based distributed model of surface and subsurface flow will be used to simulate the variability of macropores spatial structure and its effect on the flow behaviour. This model will be validated by simulating the observed rainfall events. Upscaling from field scale to catchment scale will be done to understand the effect of macropores variability on larger scales by applying spatial stochastic methods. The first phase in this study is the installation and monitoring configuration of video cameras and soil moisture monitoring equipment to obtain the initial data of overland flow occurrence and soil moisture state relationships.

Doppler flowmeter

DOEpatents

Karplus, H.H.B.; Raptis, A.C.

1981-11-13

A Doppler flowmeter impulses an ultrasonic fixed-frequency signal obliquely into a slurry flowing in a pipe and a reflected signal is detected after having been scattered off of the slurry particles, whereby the shift in frequencies between the signals is proportional to the slurry velocity and hence slurry flow rate. This flowmeter filters the Doppler frequency-shift signal, compares the filtered and unfiltered shift signals in a divider to obtain a ratio, and then further compares this ratio against a preset fractional ratio. The flowmeter utilizes a voltage-to-frequency convertor to generate a pulsed signal having a determinable rate of repetition precisely proportional to the divergence of the ratios. The pulsed signal serves as the input control for a frequency-controlled low-pass filter, which provides thereby that the cutoff frequency of the filtered signal is known. The flowmeter provides a feedback control by minimizing the divergence. With the cutoff frequency and preset fractional ratio known, the slurry velocity and hence flow will also be determinable.

Doppler flowmeter

DOEpatents

Karplus, Henry H. B.; Raptis, Apostolos C.

1983-01-01

A Doppler flowmeter impulses an ultrasonic fixed-frequency signal obliquely into a slurry flowing in a pipe and a reflected signal is detected after having been scattered off of the slurry particles, whereby the shift in frequencies between the signals is proportional to the slurry velocity and hence slurry flow rate. This flowmeter filters the Doppler frequency-shift signal, compares the filtered and unfiltered shift signals in a divider to obtain a ratio, and then further compares this ratio against a preset fractional ratio. The flowmeter utilizes a voltage-to-frequency convertor to generate a pulsed signal having a determinable rate of repetition precisely proportional to the divergence of the ratios. The pulsed signal serves as the input control for a frequency-controlled low-pass filter, which provides thereby that the cutoff frequency of the filtered signal is known. The flowmeter provides a feedback control by minimizing the divergence. With the cutoff frequency and preset fractional ratio known, the slurry velocity and hence flow will also be determinable.

Influence of Hydrological Flow Paths on Rates and Forms of Nitrogen Losses from Mediterranean Watersheds

NASA Astrophysics Data System (ADS)

Lohse, K. A.; Sanderman, J.; Amundson, R. G.

2005-12-01

Patterns of precipitation and runoff in California are changing and likely to influence the structure and functioning of watersheds. Studies have demonstrated that hydrologic flushing during seasonal transitions in Mediterranean ecosystems can exert a strong control on nitrogen (N) export, yet few studies have examined the influence of different hydrological flow paths on rates and forms of nitrogen (N) losses. Here we illuminate the influence of variations in precipitation and hydrological pathways on the rate and form of N export along a toposequence of a well-characterized Mediterranean catchment in northern California. As a part of a larger study examining particulate and dissolved carbon loss, we analyzed seasonal patterns of dissolved organic nitrogen (DON), nitrate and ammonium concentrations in rainfall, throughfall, matrix and preferential flow, and stream samples over the course of one water year. We also analyzed seasonal soil N dynamics along this toposequence. During the transition to the winter rain season, but prior to any soil water displacement to the stream, DON and nitrate moved through near-surface soils as preferential flow. Once hillslope soils became saturated, saturated subsurface flow flushed nitrate from the hollow resulting in high stream nitrate/DON concentrations. Between storms, stream nitrate/DON concentrations were lower and appeared to reflect deep subsurface water flow chemistry. During the transition to the wet season, rates of soil nitrate production were high in the hollow relative to the hillslope soils. In the spring, these rates systematically declined as soil moisture decreased. Results from our study suggest seasonal fluctuations in soil moisture control soil N cycling and seasonal changes in the hydrological connection between hillslope soils and streams control the seasonal production and export of hydrologic N.

Diversity and feeding strategies of soil microfauna along elevation gradients in Himalayan cold deserts

PubMed Central

Háněl, Ladislav; Řeháková, Klára; Doležal, Jiří

2017-01-01

High-elevation cold deserts in Tibet and Himalaya are one of the most extreme environments. One consequence is that the diversity of macrofauna in this environment is often limited, and soil microorganisms have a more influential role in governing key surface and subsurface bioprocesses. High-elevation soil microfauna represent important components of cold ecosystems and dominant consumers of microbial communities. Still little is known about their diversity and distribution on the edge of their reproductive and metabolic abilities. In this study, we disentangle the impact of elevation and soil chemistry on diversity and distribution of rotifers, nematodes and tardigrades and their most frequent feeding strategies (microbial filter-feeders, bacterivores, fungivores, root-fungal feeders, omnivores) along two contrasting altitudinal gradients in Indian NW Himalaya (Zanskar transect from 3805 to 4714 m a.s.l.) and southwestern Tibet (Tso Moriri transect from 4477 to 6176 m a.s.l.), using a combination of multivariate analysis, variation partitioning and generalized additive models. Zanskar transect had higher precipitation, soil moisture, organic matter and available nutrients than dry Tso Moriri transect. In total, 40 species of nematodes, 19 rotifers and 1 tardigrade were discovered. Species richness and total abundance of rotifers and nematodes showed mid-elevation peaks in both investigated transects. The optimum for rotifers was found at higher elevation than for nematodes. Diversity and distribution of soil microfauna was best explained by soil nitrogen, phosphorus and organic matter. More fertile soils hosted more diverse and abundant faunal communities. In Tso Moriri, bacterivores represented 60% of all nematodes, fungivores 35%, root-fungal feeders 1% and omnivores 3%. For Zanskar the respective proportions were 21%, 13%, 56% and 9%. Elevational optima of different feeding strategies occurred in Zanskar in one elevation zone (4400–4500 m), while in Tso Moriri each feeding strategy had their unique optima with fungivores at 5300 m (steppes), bacterivores at 5500 m (alpine grassland), filter-feeders at 5600 m and predators and omnivores above 5700 m (subnival zone). Our results shed light on the diversity of microfauna in the high-elevation cold deserts and disentangle the role of different ecological filters in structuring microfaunal communities in the rapidly-warming Himalayas. PMID:29131839

Flow pathways and sediment trapping in a field-scale vegetative filter

Treesearch

M. J. Helmers; D. E. Eisenhauer; Mike G. Dosskey; T. G. Franti; J. M. Brothers; M. C. McCullough

2005-01-01

Vegetative filters (VF) are a best management practive installed in many areas to control sediment movement to water bodies. It is commonly assumed that runoff proceeds perpendicularly across a VF as sheet flow. However, there is little research information on natural pathways of water movement and performance of field-scale VF. The objectives of this study were: (1)...

40 CFR 141.76 - Recycle provisions.

Code of Federal Regulations, 2010 CFR

2010-07-01

... recycle spent filter backwash water, thickener supernatant, or liquids from dewatering processes must meet... the State in writing by Decemeber 8, 2003, if the system recycles spent filter backwash water... the origin of all flows which are recycled (including, but not limited to, spent filter backwash water...

40 CFR 141.76 - Recycle provisions.

Code of Federal Regulations, 2011 CFR

2011-07-01

... recycle spent filter backwash water, thickener supernatant, or liquids from dewatering processes must meet... the State in writing by Decemeber 8, 2003, if the system recycles spent filter backwash water... the origin of all flows which are recycled (including, but not limited to, spent filter backwash water...

40 CFR 141.76 - Recycle provisions.

Code of Federal Regulations, 2012 CFR

2012-07-01

... recycle spent filter backwash water, thickener supernatant, or liquids from dewatering processes must meet... the State in writing by Decemeber 8, 2003, if the system recycles spent filter backwash water... the origin of all flows which are recycled (including, but not limited to, spent filter backwash water...

40 CFR 141.76 - Recycle provisions.

Code of Federal Regulations, 2013 CFR

2013-07-01

... recycle spent filter backwash water, thickener supernatant, or liquids from dewatering processes must meet... the State in writing by Decemeber 8, 2003, if the system recycles spent filter backwash water... the origin of all flows which are recycled (including, but not limited to, spent filter backwash water...

40 CFR 141.76 - Recycle provisions.

Code of Federal Regulations, 2014 CFR

2014-07-01

... recycle spent filter backwash water, thickener supernatant, or liquids from dewatering processes must meet... the State in writing by Decemeber 8, 2003, if the system recycles spent filter backwash water... the origin of all flows which are recycled (including, but not limited to, spent filter backwash water...

Effect of filter media size, mass flow rate and filtration stage number in a moving-bed granular filter on the yield and properties of bio-oil from fast pyrolysis of biomass.

PubMed

Paenpong, Chaturong; Inthidech, Sudsakorn; Pattiya, Adisak

2013-07-01

Fast pyrolysis of cassava rhizome was performed in a bench-scale fluidised-bed reactor unit incorporated with a cross-flow moving-bed granular filter. The objective of this research was to examine several process parameters including the granular size (425-1160 μm) and mass flow rate (0-12 g/min) as well as the number of the filtration stages (1-2 stages) on yields and properties of bio-oil. The results showed that the bio-oil yield decreased from 57.7 wt.% to 42.0-49.2 wt.% when increasing the filter media size, the mass flow rate and the filtration stage number. The effect of the process parameters on various properties of bio-oil is thoroughly discussed. In general, the bio-oil quality in terms of the solids content, ash content, initial viscosity, viscosity change and ageing rate could be enhanced by the hot vapour granular filtration. Therefore, bio-oil of high stability could be produced by the pyrolysis reactor configuration designed in this work. Copyright © 2013 Elsevier Ltd. All rights reserved.

Using a trait-based approach to link microbial community composition and functioning to soil salinity

NASA Astrophysics Data System (ADS)

Rath, Kristin; Fierer, Noah; Rousk, Johannes

2017-04-01

Our knowledge of the dynamics structuring microbial communities and the consequences this has for soil functions is rudimentary. In particular, predictions of the response of microbial communities to environmental change and the implications for associated ecosystem processes remain elusive. Understanding how environmental factors structure microbial communities and regulate the functions they perform is key to a mechanistic understanding of how biogeochemical cycles respond to environmental change. Soil salinization is an agricultural problem in many parts of the world. The activity of soil microorganisms is reduced in saline soils compared to non-saline soil. However, soil salinity often co-varies with other factors, making it difficult to assign responses of microbial communities to direct effects of salinity. A trait-based approach allows us to connect the environmental factor salinity with the responses of microbial community composition and functioning. Salinity along a salinity gradient serves as a filter for the community trait distribution of salt tolerance, selecting for higher salt tolerance at more saline sites. This trait-environment relationship can be used to predict responses of microbial communities to environmental change. Our aims were to (i) use salinity along natural salinity gradients as an environmental filter, and (ii) link the resulting filtered trait-distributions of the communities (the trait being salt tolerance) to the community composition. Soil samples were obtained from two replicated salinity gradients along an Australian salt lake, spanning a wide range of soil salinities (0.1 dS m-1 to >50 dS m-1). In one of the two gradients salinity was correlated with pH. Community trait distributions for salt tolerance were assessed by establishing dose-dependences for extracted bacterial communities using growth rate assays. In addition, functional parameters were measured along the salt gradients. Community composition of sites was compared through 16S rRNA gene amplicon sequencing. Microbial community composition changed greatly along the salinity gradients. Using the salt-tolerance assessments to estimate bacterial trait-distributions we could determine substantial differences in tolerance to salt revealing a strong causal connection between environment and trait distributions. By constraining the community composition with salinity tolerance in ordinations, we could assign which community differences were directly due to a shift in community trait distributions. These analyses revealed that a substantial part (up to 30%) of the community composition differences were directly driven by environmental salt concentrations.. Even though communities in saline soils had trait-distributions aligned to their environment, their performance (respiration, growth rates) was lower than those in non-saline soils and remained low even after input of organic material. Using a trait-based approach we could connect filtered trait distributions along environmental gradients, to the composition of the microbial community. We show that soil salinity played an important role in shaping microbial community composition by selecting for communities with higher salt tolerance. The shift toward bacterial communities with trait distributions matched to salt environments probably compensated for much of the potential loss of function induced by salinity, resulting in a degree of apparent functional redundancy for decomposition. However, more tolerant communities still showed reduced functioning, suggesting a trade-off between salt tolerance and performance.

Role of soil organic carbon and colloids in sorption and transport of TNT, RDX and HMX in training range soils.

PubMed

Sharma, Prasesh; Mayes, Melanie A; Tang, Guoping

2013-08-01

Contamination of soils and groundwater by munitions compounds (MCs) is of significant concern at many U.S. Department of Defense sites. Soils were collected from operational training ranges in Maryland (APG), Massachusetts (MMR-B and MMR-E) and Washington (JBLM) and sorption and transport studies were conducted to investigate the effects of soil organic carbon (OC) and textural clay content on fate of dissolved MCs (TNT, RDX, HMX). Sorption experiments showed higher distribution coefficients [TNT:42-68 L kg(-1), RDX:6.9-8.7 L kg(-1) and HMX:2.6-3.1 L kg(-1)] in OC rich soils (JBLM, MMR-E) compared to clay rich soils (MMR-B and APG) [TNT:19-21 L kg(-1), RDX:2.5-3.4 L kg(-1), HMX:0.9-1.2 L kg(-1)]. In column experiments, breakthrough of MCs was faster in MMR-B and APG compared to MMR-E and JBLM soils. Among TNT, RDX and HMX, breakthrough was fastest for RDX followed by HMX and TNT for all columns. Defining the colloidal fraction as the difference between unfiltered samples and samples filtered with a 3 kDa filter, ~36%, ~15% and ~9% of TNT, RDX and HMX were found in the colloidal fraction in the solutions from sorption experiments, and around 20% of TNT in the effluent from the transport experiments. Results demonstrate that OC rich soils may enhance sorption and delay transport of TNT, RDX and HMX compared to clay-rich soils. Further, transport of TNT may be associated with soil colloid mobilization. Copyright © 2013 Elsevier Ltd. All rights reserved.

Glass Frit Filters for Collecting Metal Oxide Nanoparticles

NASA Technical Reports Server (NTRS)

Ackerman, John; Buttry, Dan; Irvine, Geoffrey; Pope, John

2005-01-01

Filter disks made of glass frit have been found to be effective as means of high-throughput collection of metal oxide particles, ranging in size from a few to a few hundred nanometers, produced in gas-phase condensation reactors. In a typical application, a filter is placed downstream of the reactor and a valve is used to regulate the flow of reactor exhaust through the filter. The exhaust stream includes a carrier gas, particles, byproducts, and unreacted particle-precursor gas. The filter selectively traps the particles while allowing the carrier gas, the byproducts, and, in some cases, the unreacted precursor, to flow through unaffected. Although the pores in the filters are much larger than the particles, the particles are nevertheless trapped to a high degree: Anecdotal information from an experiment indicates that 6-nm-diameter particles of MnO2 were trapped with greater than 99-percent effectiveness by a filtering device comprising a glass-frit disk having pores 70 to 100 micrometer wide immobilized in an 8-cm-diameter glass tube equipped with a simple twist valve at its downstream end.

Macropore system characteristics controls on non-reactive solute transport at different flow rates

NASA Astrophysics Data System (ADS)

Larsbo, Mats; Koestel, John

2014-05-01

Preferential flow and transport in macroporous soils are important pathways for the leaching of agrochemicals through soils. Preferential solute transport in soil is to a large extent determined by the macropore system characteristics and the water flow conditions. The importance of different characteristics of the macropore system is likely to vary with the flow conditions. The objective of this study was to determine which properties of the macropore system that control the shape of non-reactive tracer solute breakthrough curves at different steady-state flow rates. We sampled five undisturbed columns (20 cm high, 20 cm diameter) from the soil surface of four soils with clay contents between 21 and 50 %. Solute transport experiments were carried out under unsaturated conditions at 2, 4, 6, 8 and 12 mm h-1 flow rates. For each flow rate a pulse of potassium bromide solution was applied at the soil surface and the electrical conductivity was measured with high temporal resolution in the column effluent. We used the 5 % arrival time and the holdback factor to estimate the degree of preferential transport from the resulting breakthrough curves. Unsaturated hydraulic conductivities were measured at the soil surface of the columns using a tension disc infiltrometer. The macropore system was imaged by industrial X-ray computed tomography at a resolution of 125 μm in all directions. Measures of the macropore system characteristics including measures of pore continuity were calculated from these images using the ImageJ software. Results show that the degree of preferential transport is generally increasing with flow rate when larger pores become active in the transport. The degree of preferential flow was correlated to measures of macropore topology. This study show that conclusions drawn from experiments carried out at one flow rate should generally not be extrapolated to other flow rates.

Preferential flow, connectivity and the principle of "minimum time to equilibrium": a new perspective on environmental water flow

NASA Astrophysics Data System (ADS)

Zehe, E.; Blume, T.; Bloeschl, G.

2008-12-01

Preferential/rapid flow and transport is known as one key process in soil hydrology for more than 20 years. It seems to be rather the rule, than the exception. It occurs in soils, in surface rills and river networks. If connective preferential are present at any scale, they crucially control water flow and solute transport. Why? Is there an underlying principle? If energy is conserved a system follows Fermat's principle of minimum action i.e. it follows the trajectory that minimise the integral of the total energy/ La Grangian over time. Hydrological systems are, however, non-conservative as surface and subsurface water flows dissipate energy. From thermodynamics it is well known that natural processes minimize the free energy of the system. For hydrological systems we suggest, therefore, that flow in a catchment arranges in such a way that time to a minimum of free energy becomes minimal for a given rainfall input (disturbance) and under given constraints. Free energy in a soil is determined by potential energy and capillary energy. The pore size distribution of the soil, soil structures, depth to groundwater and most important vegetation make up the constraints. The pore size distribution determines whether potential energy or capillarity dominates the free energy of the soil system. The first term is minimal when the pore space is completely de-saturated the latter becomes minimal at soil saturation. Hence, the soil determines a) the amount of excess (gravity) water that has to be exported from the soil to reach a minimum state of free energy and b) whether redistribution or groundwater recharge is more efficient to reach that equilibrium. On the other hand, the pore size distribution of the soil and the connectivity of preferential pathways (root channels, worm holes and cracks) determine flow velocities and the redistribution of water within the pore space. As water flow and ground water recharge are fast in sandy soils and capillary energy is of minor importance, connective preferential pathways do not mean any advantage for an efficient transition to an equilibrium in these systems. In fine grained soils Darcy velocities and therefore redistribution of water is 2-4 orders of magnitude slower. As capillary energy dominates in these soils an effective redistribution of water within the pore space is crucial for a fast transition of system to an equilibrium state. Connective preferential pathways ore even cracks allow a faster redistribution of water and seem therefore necessary for a fast transition into a state of minimum free energy. The suggested principle "of minimum time to equilibrium" may explain the "advantage" of preferential flow as a much more efficient dissipation of energy in fine grained soils and therefore why connective preferential pathways control environmental flow. From a fundamental, long term perspective the principle may help us to understand whether and why soil structures and even cracks evolve in different landscapes and climates and b) to link soil hydrology and (landscape) ecology. Along the lines the proposed study will present model results to test the stated hypothesis.

Trench Reveals Two Faces of Soils

NASA Technical Reports Server (NTRS)

2004-01-01

This approximate true-color image mosaic from the panoramic camera on the Mars Exploration Rover Opportunity shows a trench dug by the rover in the vicinity of the 'Anatolia' region. Two imprints from the rover's Mossbauer spectrometer instrument were left in the exposed soils. Detailed comparisons between soils exposed at the surface and those found at depth reveal that surface soils have higher levels of hematite while subsurface soils show fine particles derived from basalt. The trench is approximately 11 centimeters deep. This image was taken on sol 81 with the panoramic camera's 430-, 530- and 750-nanometer filters.

Colloid Mobilization in a Fractured Soil: Effect of Pore-Water Exchange between Preferential Flow Paths and Soil Matrix.

PubMed

Mohanty, Sanjay K; Saiers, James E; Ryan, Joseph N

2016-03-01

Exchange of water and solutes between contaminated soil matrix and bulk solution in preferential flow paths has been shown to contribute to the long-term release of dissolved contaminants in the subsurface, but whether and how this exchange can affect the release of colloids in a soil are unclear. To examine this, we applied rainfall solutions of different ionic strength on an intact soil core and compared the resulting changes in effluent colloid concentration through multiple sampling ports. The exchange of water between soil matrix and the preferential flow paths leading to each port was characterized on the basis of the bromide (conservative tracer) breakthrough time at the port. At individual ports, two rainfalls of a certain ionic strength mobilized different amounts of colloids when the soil was pre-exposed to a solution of lower or higher ionic strength. This result indicates that colloid mobilization depended on rainfall solution history, which is referred as colloid mobilization hysteresis. The extent of hysteresis was increased with increases in exchange of pore water and solutes between preferential flow paths and matrix. The results indicate that the soil matrix exchanged the old water from the previous infiltration with new infiltrating water during successive infiltration and changed the pore water chemistry in the preferential flow paths, which in turn affected the release of soil colloids. Therefore, rainfall solution history and soil heterogeneity must be considered to assess colloid mobilization in the subsurface. These findings have implications for the release of colloids, colloid-associated contaminants, and pathogens from soils.

BLAISDELL SLOW SAND FILTER WASHING MACHINE. VIEW LOOKING SOUTH. THE ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

BLAISDELL SLOW SAND FILTER WASHING MACHINE. VIEW LOOKING SOUTH. THE OUTSIDE FACE OF THE NORTH WALL OF SETTLING RESERVOIR NO. 3 IS SEEN AT THE RIGHT. THE SETTLING RESERVOIR IS ELEVATED ABOVE THE FILTERING RESERVOIR TO ACHIEVE GRAVITY WATER FLOW FROM THE SETTLING RESERVOIR INTO THE FILTERING RESERVOIR. - Yuma Main Street Water Treatment Plant, Blaisdell Slow Sand Filter Washing Machine, Jones Street at foot of Main Street, Yuma, Yuma County, AZ

Enhancement of microfluidic particle separation using cross-flow filters with hydrodynamic focusing

PubMed Central

Chiu, Yun-Yen; Huang, Chen-Kang

2016-01-01

A microfluidic chip is proposed to separate microparticles using cross-flow filtration enhanced with hydrodynamic focusing. By exploiting a buffer flow from the side, the microparticles in the sample flow are pushed on one side of the microchannels, lining up to pass through the filters. Meanwhile a larger pressure gradient in the filters is obtained to enhance separation efficiency. Compared with the traditional cross-flow filtration, our proposed mechanism has the buffer flow to create a moving virtual boundary for the sample flow to actively push all the particles to reach the filters for separation. It further allows higher flow rates. The device only requires soft lithograph fabrication to create microchannels and a novel pressurized bonding technique to make high-aspect-ratio filtration structures. A mixture of polystyrene microparticles with 2.7 μm and 10.6 μm diameters are successfully separated. 96.2 ± 2.8% of the large particle are recovered with a purity of 97.9 ± 0.5%, while 97.5 ± 0.4% of the small particle are depleted with a purity of 99.2 ± 0.4% at a sample throughput of 10 μl/min. The experiment is also conducted to show the feasibility of this mechanism to separate biological cells with the sample solutions of spiked PC3 cells in whole blood. By virtue of its high separation efficiency, our device offers a label-free separation technique and potential integration with other components, thereby serving as a promising tool for continuous cell filtration and analysis applications. PMID:26858812

Meshless bubble filter using ultrasound for extracorporeal circulation and its effect on blood.

PubMed

Mino, Koji; Imura, Masato; Koyama, Daisuke; Omori, Masayoshi; Kawarabata, Shigeki; Sato, Masafumi; Watanabe, Yoshiaki

2015-02-01

A bubble filter with no mesh structure for extracorporeal circulation using ultrasound was developed. Hemolysis was evaluated by measuring free hemoglobin (FHb). FHb in 120 mL of bovine blood was measured in acoustic standing-wave fields. With a sound pressure amplitude of 60 kPa at driving frequencies of 1 MHz, 500 kHz and 27 kHz for 15 min. FHb values were 641.6, 2575 and 8903 mg/dL, respectively. Thus, hemolysis was inhibited with higher driving frequencies when the same sound pressure amplitude was applied. An ultrasound bubble filter with a resonance frequency of 1 MHz was designed. The filtering characteristics of the flowing microbubbles were investigated with a circulation system using bovine blood with a flow rate of 5.0 L/min. Approximately 99.1% of microbubbles were filtered with 250 kPa and a flow of 5.0 L/min. Hemolysis decreased as the sound pressure decreased; FHb values were 225.8 and 490.7 mg/dL when using 150 and 200 kPa, respectively. Copyright © 2015 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.

On the ``optimal'' spatial distribution and directional anisotropy of the filter-width and grid-resolution in large eddy simulation

NASA Astrophysics Data System (ADS)

Toosi, Siavash; Larsson, Johan

2017-11-01

The accuracy of an LES depends directly on the accuracy of the resolved part of the turbulence. The continuing increase in computational power enables the application of LES to increasingly complex flow problems for which the LES community lacks the experience of knowing what the ``optimal'' or even an ``acceptable'' grid (or equivalently filter-width distribution) is. The goal of this work is to introduce a systematic approach to finding the ``optimal'' grid/filter-width distribution and their ``optimal'' anisotropy. The method is tested first on the turbulent channel flow, mainly to see if it is able to predict the right anisotropy of the filter/grid, and then on the more complicated case of flow over a backward-facing step, to test its ability to predict the right distribution and anisotropy of the filter/grid simultaneously, hence leading to a converged solution. This work has been supported by the Naval Air Warfare Center Aircraft Division at Pax River, MD, under contract N00421132M021. Computing time has been provided by the University of Maryland supercomputing resources (http://hpcc.umd.edu).

Heat and moisture exchangers and breathing system filters: their use in anaesthesia and intensive care. Part 2 - practical use, including problems, and their use with paediatric patients.

PubMed

Wilkes, A R

2011-01-01

Heat and moisture exchangers and breathing system filters are intended to replace the normal warming, humidifying and filtering functions of the upper airways. The first part of this review considered the history, principles of operation and efficiency of these devices. The aim of this part of the review is to summarise recent guidelines on the use of these devices and outline the problems that can occur. In particular, the effect of these devices on gas analysis, dead space, resistance to gas flow and blockage of the breathing system is considered. In children, it is important to consider the addition of dead space and resistance to gas flow. A body weight of 2.5 kg is probably the lower weight limit for use with heat and moisture exchangers, and 3 kg for filters. The resistance to gas flow of a heat- and moisture-exchanging filter added to a Mapleson F breathing system can cause a delay in the induction of anaesthesia. © 2010 The Author. Anaesthesia © 2010 The Association of Anaesthetists of Great Britain and Ireland.

Cross-flow electrofilter and method

DOEpatents

Gidaspow, Dimitri; Lee, Chang H.; Wasan, Darsh T.

1980-01-01

A filter for clarifying carbonaceous liquids containing finely divided solid particles of, for instance, unreacted coal, ash and other solids discharged from a coal liquefaction process is presented. The filter includes two passageways separated by a porous filter medium. In one preferred embodiment the filter medium is of tubular shape to form the first passageway and is enclosed within an outer housing to form the second passageway within the annulus. An electrode disposed in the first passageway, for instance along the tube axis, is connected to a source of high voltage for establishing an electric field between the electrode and the filter medium. Slurry feed flows through the first passageway tangentially to the surfaces of the filter medium and the electrode. Particles from the feed slurry are attracted to the electrode within the first passageway to prevent plugging of the porous filter medium while carbonaceous liquid filters into the second passageway for withdrawal. Concentrated slurry is discharged from the first passageway at an end opposite to the feed slurry inlet. Means are also provided for the addition of diluent and a surfactant into the slurry to control relative permittivity and the electrophoretic mobility of the particles.

Cross flow electrofilter and method

DOEpatents

Gidaspow, Dimitri; Lee, Chang H.; Wasan, Darsh T.

1981-01-01

A filter for clarifying carbonaceous liquids containing finely divided solid particles of, for instance, unreacted coal, ash and other solids discharged from a coal liquefaction process is presented. The filter includes two passageways separated by a porous filter medium. In one preferred embodiment the filter medium is of tubular shape to form the first passageway and is enclosed within an outer housing to form the second passageway within the annulus. An electrode disposed in the first passageway, for instance along the tube axis, is connected to a source of high voltage for establishing an electric field between the electrode and the filter medium. Slurry feed flows through the first passageway tangentially to the surfaces of the filter medium and the electrode. Particles from the feed slurry are attracted to the electrode within the first passageway to prevent plugging of the porous filter medium while carbonaceous liquid filters into the second passageway for withdrawal. Concentrated slurry is discharged from the first passageway at an end opposite to the feed slurry inlet. Means are also provided for the addition of diluent and a surfactant into the slurry to control relative permittivity and the electrophoretic mobility of the particles.

Weathering behavior of REE-Y in a granitic soil profile (Case of Strengbach watershed)

NASA Astrophysics Data System (ADS)

Gangloff, Sophie; Stille, Peter; Chabaux, François

2017-04-01

Rare earth elements and yttrium (REE-Y) can be used as tracers of bedrock weathering and soil formation. One of the aims of this study is to better understand the different phenomena which impact the REE-Y mobilization and modify the REE-Y pattern along a soil profile. Our study has been performed on a granitic soil profile and soil solutions corresponding, sampled in a forest parcel covered with spruces from the Strengbach catchment. The behavior of the REE-Y pattern are compared with previously published results. The samples were collected from 2009 to 2013 and ultra-filtered to determine the spatial and temporal influence as well as that of the colloidal and dissolved fractions on the evolution of the REE-Y patterns. The EFTi of the soil indicates that during alteration process, phosphate minerals and zircon might be dissolved and induce the formation of secondary mineral phase like xenotime in the deeper soil horizons. The ultra-filtered soil solutions from humic horizon show that the REE-Y are principally enriched in the colloidal fraction controlling the REE-Y dynamic while in the deeper soil solutions colloidal and dissolved fractions influence the REE-Y. The mobility of REE-Y is controlled by the dissolution of the zircon and phosphate minerals, the precipitation of the REE-Y(PO4) and the evolution of OC with depth. The comparative study of the soil profile, soil water extracts and soil solutions show that (Eu*/Eu)DS anomaly reflects weathering of plagioclase in the micropores and the migration of the released Eu to the macropores, the (Ce*/Ce) anomaly, is stabilized by the electron shuttling of the humic acid (aromaticity) and provides information on the redox conditions only in the deeper soil horizons depleted in humic acid and finally the HREE enrichment in the deeper soil solutions results from the partial dissolution of secondary minerals in the upper soil horizons (above 30 cm depth).

A novel enhanced diffusion sampler for collecting gaseous pollutants without air agitation.

PubMed

Pan, Xuelian; Zhuo, Shaojie; Zhong, Qirui; Chen, Yuanchen; Du, Wei; Cheng, Hefa; Wang, Xilong; Zeng, Eddy Y; Xing, Baoshan; Tao, Shu

2018-03-06

A novel enhanced diffusion sampler for collecting gaseous phase polycyclic aromatic hydrocarbons (PAHs) without air agitation is proposed. The diffusion of target compounds into a sampling chamber is facilitated by continuously purging through a closed-loop flow to create a large concentration difference between the ambient air and the air in the sampling chamber. A glass-fiber filter-based prototype was developed. It was demonstrated that the device could collect gaseous PAHs at a much higher rate (1.6 ± 1.4 L/min) than regular passive samplers, while the ambient air is not agitated. The prototype was also tested in both the laboratory and field for characterizing the concentration gradients over a short distance from the soil surface. The sampler has potential to be applied in other similar situations to characterize the concentration profiles of other chemicals.

Volcanic Aerosol Phosphorus, Chlorine, and Sulfur at Kilauea, Hawaii

DOE Office of Scientific and Technical Information (OSTI.GOV)

Darzi, M.; Winchester, J.W.

1982-12-20

Aerosol concentrations of P, Cl, S, and major soil-derived elements were measured sequentially at the Hawaiian Volcano Observatory (HVO) from March to September 1979, with 3.7-hour time resolution using a Nucleopore-filter sampler. The filters were analyzed by particle-induced X ray emission (PIXE). Comparison with diurnal variations in the air flow inferred from major soil elements, e.g., Fe, as well as measurements made previously at fumaroles near HVO, indicate that the P, C. and S may be attributed mainly to volcanic emissions from Kilauea. From April 23 to June 30, P was found with concentrations up to 1000 ng m/sup -3/;more » but before and after those dates, P was generally below the detection limit of 50--80 ng m/sup -3/. Cl and S were frequently found over the entire sampling period, also with concentrations up to 1000 ng m/sup -3/. However, when P was found, Cl was almost never detected simultaneously. The mutually exclusive occurrences of P and Cl suggest volatility release of HCl from aerosol particles by reaction with strong acid associated with P. If strong acidity is due to H/sub 2/SO/sub 4/, it is not well predicted by S, which may also include other sulfates or sulfur, since aerosol S concentrations are not well correlated with P or Cl. The behavior of these three elements suggests that the volcanic sources of P are more localized than those of Cl or S. It is significant that concentrations of aerosol P can be as high as aerosol Cl and S, all apparently of primary volcanic origin, indicating that volcanism may be an important, but hitherto unrecognized, process in the atmosphere goechemical cycling of phosphorus.« less

Determination of Hg concentration in gases by PIXE

NASA Astrophysics Data System (ADS)

Dutkiewicz, E.; van Kuijen, W. J. P.; Munnik, F.; Mutsaers, P. H. A.; Rokita, E.; de Voigt, M. J. A.

1992-05-01

A method for determination of the concentration of mercury in the gaseous phase is described. In the first step of the method a stable sulphur-mercury complex is formed. For this purpose sulphur is deposited on a filter and the investigated gas flows through the filter. Millipore filters and the deposition of sulphur from Na2S2O3 * 5H2O solution were found to be most suitable. The amount of Hg absorbed on the filter was determined by PIXE or by NAA in the second step of the method. An optimization of proton energy was performed in the PIXE analysis to obtain the maximal signal-to-background ratio. The detection limit of the method, expressed as the minimal amount of Hg which has to flow through the filter equals to 30 and 2 ng for PIXE and NAA techniques, respectively. Applications of the method are also described.

Modeling the system dynamics for nutrient removal in an innovative septic tank media filter.

PubMed

Xuan, Zhemin; Chang, Ni-Bin; Wanielista, Martin

2012-05-01

A next generation septic tank media filter to replace or enhance the current on-site wastewater treatment drainfields was proposed in this study. Unit operation with known treatment efficiencies, flow pattern identification, and system dynamics modeling was cohesively concatenated in order to prove the concept of a newly developed media filter. A multicompartmental model addressing system dynamics and feedbacks based on our assumed microbiological processes accounting for aerobic, anoxic, and anaerobic conditions in the media filter was constructed and calibrated with the aid of in situ measurements and the understanding of the flow patterns. Such a calibrated system dynamics model was then applied for a sensitivity analysis under changing inflow conditions based on the rates of nitrification and denitrification characterized through the field-scale testing. This advancement may contribute to design such a drainfield media filter in household septic tank systems in the future.

Effects of digestion, chemical separation, and deposition on Po-210 quantitative analysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Seiner, Brienne N.; Morley, Shannon M.; Beacham, Tere A.

Polonium-210 is a radioactive isotope often used to study sedimentation processes, food chains, aerosol behavior, and atmospheric circulations related to environmental sciences. Materials for the analysis of Po-210 range from tobacco leaves or cotton fibers, to soils and sediments. The purpose of this work was to determine polonium losses from a variety of sample types (soil, cotton fiber, and air filter) due to digestion technique, chemical separation, and deposition method for alpha energy analysis. Results demonstrated that yields from a perchloric acid wet-ash were similar to that from a microwave digestion. Both were greater than the dry-ash procedure. The poloniummore » yield from the perchloric acid wet ash was 87 ± 5%, the microwave digestion had a yield of 100 ± 7%, and the dry ash had a yield of 38 ± 5%. The chemical separation of polonium by an anion exchange resin was used only on the soil samples due to the complex nature of this sample. The yield of Po-209 tracer after chemical separation and deposition for alpha analysis was 83 ± 7% for the soil samples. Spontaneous deposition yields for the cotton and air filters were 87 ± 4% and 92 ± 6%, respectively. Based on the overall process yields for each sample type the amount of Po-210 was quantified using alpha energy analysis. The soil contained 0.18 ± 0.08 Bq/g, the cotton swipe contained 0.7 mBq/g, and the air filter contained 0.04 ± 0.02 mBq/g. High and robust yields of polonium are possible using a suitable digestion, separation, and deposition method.« less

77 FR 7523 - Airworthiness Directives; Airbus Airplanes

Federal Register 2010, 2011, 2012, 2013, 2014

2012-02-13

... with 2 flow metering systems equipped with upgraded water absorbing filter elements. This AD was prompted by reports of partial blockage of a certain water absorbing filter element. We are issuing this AD to prevent partial blockage of a certain water absorbing filter element, which could lead to...

Soil detachment by overland flow under different vegetation restoration models in the loess plateau of China

USDA-ARS?s Scientific Manuscript database

Land use change has significant effects on soil properties and vegetation cover and thus probably affects soil detachment by overland flow. Few studies were conducted to evaluate the effect of restoration models on the soil detachment process in the Loess Plateau in the past decade during which a Gr...

Small scale recirculating vertical flow constructed wetland (RVFCW) for the treatment and reuse of wastewater.

PubMed

Gross, A; Sklarz, M Y; Yakirevich, A; Soares, M I M

2008-01-01

The quantity of freshwater available worldwide is declining, revealing a pressing need for its more efficient use. Moreover, in many developing countries and lightly populated areas, raw wastewater is discarded into the environment posing serious ecological and health problems. Unfortunately, this situation will persist unless low-cost, effective and simple technologies are brought in. The aim of this study is to present such a treatment method, a novel setup which is termed recirculating vertical flow constructed wetland (RVFCW). The RVFCW is composed of two components: (i) a three-layer bed consisting of planted organic soil over an upper layer of filtering media (i.e. tuff or beads) and a lower layer of limestone pebbles, and (ii) a reservoir located beneath the bed. Wastewater flows directly into the plant root zone and trickles down through the three-layer bed into the reservoir, allowing passive aeration. From the reservoir the water is recirculated back to the bed, several times, until the desired purification is achieved. The results obtained show that the RVFCW is an effective and convenient strategy to treat (domestic, grey and agro) wastewater for re-use in irrigation. The system performance is expected to be further improved once current optimization experiments and mathematical modeling studies are concluded. IWA Publishing 2008.

Effect of feeding strategies on pharmaceutical removal by subsurface flow constructed wetlands.

PubMed

Zhang, Dong Qing; Gersberg, Richard M; Hua, Tao; Zhu, Junfei; Nguyen, Anh Tuan; Law, Wing-Keung; Ng, Wun Jern; Tan, Soon Keat

2012-01-01

This study presents findings on an assessment of the effect of continuous and batch feeding strategies on the removal of selected pharmaceuticals from synthetic wastewater. Six mesocosm-scale constructed wetlands, including three horizontal subsurface flow constructed wetlands and three sand filters, were set up at the campus of Nanyang Technological University, Singapore. The findings showed that ibuprofen and diclofenac removal in the wetlands was significantly ( < 0.05) enhanced in the batch versus continuous mode. In contrast, naproxen and carbamazepine showed no significant differences ( > 0.05) in elimination under either feeding strategy. Our results also clearly showed that the presence of plants exerts a stimulatory effect on pharmaceutical removal for ibuprofen, diclofenac, and naproxen in batch and continuous mode. Estimation of the quantitative role of this stimulatory effect on pharmaceutical elimination of batch operation as compared with the effect of the presence of the higher plant alone showed that batch operation may account for 40 to 87% of the contribution conferred by the aquatic plant. The findings of this study imply that where maximal removal of pharmaceutical compounds is desired, periodic draining and filling might be the preferred operational strategy for full-scale, subsurface flow constructed wetlands. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

Scaling and pedotransfer in numerical simulations of flow and transport in soils

USDA-ARS?s Scientific Manuscript database

Flow and transport parameters of soils in numerical simulations need to be defined at the support scale of computational grid cells. Such support scale can substantially differ from the support scale in laboratory or field measurements of flow and transport parameters. The scale-dependence of flow a...

Layered Outcrops in Gusev Crater (False Color)

NASA Technical Reports Server (NTRS)

2004-01-01

One of the ways scientists collect mineralogical data about rocks on Mars is to view them through filters that allow only specific wavelengths of light to pass through the lens of the panoramic camera. NASA's Mars Exploration Rover Spirit took this false-color image of the rock nicknamed 'Tetl' at 1:05 p.m. martian time on its 270th martian day, or sol (Oct. 5, 2004) using the panoramic camera's 750-, 530-, and 430-nanometer filters. Darker red hues in the image correspond to greater concentrations of oxidized soil and dust. Bluer hues correspond to portions of rock that are not as heavily coated with soils or are not as highly oxidized.

Application of Data Assimilation with the Root Zone Water Quality Model for Soil Moisture Profile Estimation

USDA-ARS?s Scientific Manuscript database

Estimation of soil moisture has received considerable attention in the areas of hydrology, agriculture, meteorology and environmental studies because of its role in the partitioning water and energy at the land surface. In this study, the Ensemble Kalman Filter (EnKF), a popular data assimilation te...

Assimilation of active and passive microwave observations for improved estimates of soil moisture and crop growth

USDA-ARS?s Scientific Manuscript database

An Ensemble Kalman Filter-based data assimilation framework that links a crop growth model with active and passive (AP) microwave models was developed to improve estimates of soil moisture (SM) and vegetation biomass over a growing season of soybean. Complementarities in AP observations were incorpo...

Study of change of hydrophysical properties of bore mud in process of its utilization into man-induced soil

NASA Astrophysics Data System (ADS)

Gaevaya, E. V.; Bogaychuk, Y. E.; Tarasova, S. S.; Skipin, L. N.; Zaharova, E. V.

2017-10-01

The article considers the results of studies of the chemical and granulometric content and the factor of bore mud filtration in the process of its utilization. When the phosphogypsum is added, hydrophysical properties of the bore mud improve. At the same time, gradation of soil from the water-proof to weakly permeable takes place. This phenomenon is connected with recovery of filterability at the expense of ion-exchange reaction and a decrease of the silt fraction content in the bore mud. During the adding of phosphogypsum in the bore mud, pH decreased and made up 7.6-7.8 U. The decrease of the concentration of chloride-ions and sulphate-ions took place at the expense of replacement of Na+ by cations of Ca2+ that contributed to the formation of the water-stable structure with good filterability. The content of total forms of heavy metals in man-induced soil was lower than MAC (APC) for the loams. Man-induced soil has a V class of danger for the surrounding environment.

Assimilating Remote Sensing Observations of Leaf Area Index and Soil Moisture for Wheat Yield Estimates: An Observing System Simulation Experiment

NASA Technical Reports Server (NTRS)

Nearing, Grey S.; Crow, Wade T.; Thorp, Kelly R.; Moran, Mary S.; Reichle, Rolf H.; Gupta, Hoshin V.

2012-01-01

Observing system simulation experiments were used to investigate ensemble Bayesian state updating data assimilation of observations of leaf area index (LAI) and soil moisture (theta) for the purpose of improving single-season wheat yield estimates with the Decision Support System for Agrotechnology Transfer (DSSAT) CropSim-Ceres model. Assimilation was conducted in an energy-limited environment and a water-limited environment. Modeling uncertainty was prescribed to weather inputs, soil parameters and initial conditions, and cultivar parameters and through perturbations to model state transition equations. The ensemble Kalman filter and the sequential importance resampling filter were tested for the ability to attenuate effects of these types of uncertainty on yield estimates. LAI and theta observations were synthesized according to characteristics of existing remote sensing data, and effects of observation error were tested. Results indicate that the potential for assimilation to improve end-of-season yield estimates is low. Limitations are due to a lack of root zone soil moisture information, error in LAI observations, and a lack of correlation between leaf and grain growth.

The Characteristic and Activation of Mixed Andisol Soil/Bayat Clays/Rice Husk Ash as Adsorbent of Heavy Metal Chromium (Cr)

NASA Astrophysics Data System (ADS)

Pranoto; Sajidan; Suprapto, A.

2017-02-01

Chromium (Cr) concentration in water can be reduced by adsorption. This study aimed to determine the effect of Andisol soil composition/Bayat clay/husk ash, activation temperature and contact time of the adsorption capacity of Cr in the model solution; the optimum adsorption conditions and the effectiveness of ceramic filters and purifiers to reduce contaminant of Cr in the water. The mixture of Andisol soil, Bayat clay, and husk ash is used as adsorbent of metal ion of Cr(III) using batch method. The identification and characterisation of adsorbent was done with NaF test, infrared spectroscopy (FTIR), X-ray diffraction (XRD). Cr metal concentrations were analyzed by atomic absorption spectroscopy. Sorption isotherms determined by Freundlich equation and Langmuir. The optimum conditions of sorption were achieved at 150°C activation temperature, contact time of 30 minutes and a composition Andisol soil / Bayat clay / husk ash by comparison 80/10/10. The results show a ceramic filter effectively reduces total dissolved solids (TDS) and Chromium in the water with the percentage decrease respectively by 75.91% and 9.44%.

Space agriculture in micro- and hypo-gravity: A comparative study of soil hydraulics and biogeochemistry in a cropping unit on Earth, Mars, the Moon and the space station

NASA Astrophysics Data System (ADS)

Maggi, Federico; Pallud, Céline

2010-12-01

Increasing interest is developing towards soil-based agriculture as a long-term bioregenerative life support during space and planetary explorations. Contrary to hydroponics and aeroponics, soil-based cropping would offer an effective approach to sustain food and oxygen production, decompose organic wastes, sequester carbon dioxide, and filter water. However, the hydraulics and biogeochemical functioning of soil systems exposed to gravities lower than the Earth's are still unknown. Since gravity is crucial in driving water flow, hypogravity will affect nutrient and oxygen transport in the liquid and gaseous phases, and could lead to suffocation of microorganisms and roots, and emissions of toxic gases. A highly mechanistic model coupling soil hydraulics and nutrient biogeochemistry previously tested on soils on Earth ( g=9.806 m s -2) is used to highlight the effects of gravity on the functioning of cropping units on Mars (0.38 g), the Moon (0.16 g), and in the international space station (ISS, nearly 0 g). For each scenario, we have compared the net leaching of water, the leaching of NH 3, NH 4+, NO 2- and NO 3- solutes, the emissions of NH 3, CO 2, N 2O, NO and N 2 gases, the concentrations profiles of O 2, CO 2 and dissolved organic carbon (DOC) in soil, the pH, and the dynamics of various microbial functional groups within the root zone against the same control variables in the soil under terrestrial gravity. The response of the soil ecodynamics was relatively linear; gravitational accelerations lower than the Earth's resulted in 90-100% lower water leaching rates, 95-100% lower nutrient leaching rates, and lower emissions of NH 3 and NO gases (80-95% and 30-40%, respectively). Lower N loss through leaching resulted in 60-100% higher concentration of the microbial biomass, but did not alter the vertical stratification of the microbial functional groups with respect to the stratification on Earth. However, the higher biomass concentration produced higher emissions of N 2O, N 2, and CO 2 gases (80%, 200% and 40%, respectively).

Preferential flow in connected soil structures and the principle of "maximum energy dissipation": A thermodynamic perspective

NASA Astrophysics Data System (ADS)

Zehe, E.; Blume, T.; Bloeschl, G.

2009-04-01

"There is preferential flow at all scales"? This was a key message in a talk on ?Idle thoughts on a unifying theory of catchment hydrology? given by Bloeschl (2006). In this context ?preferential flow? was used to address rapid water flow along spatially connected flow paths of minimum flow resistance. Preferential flow seems in fact rather the rule than the exception. It occurs locally in non capillary macropores, at the hillslope scale in surface rills or through subsurface pipes. Rapid flow in connected biopores or sometimes shrinkage cracks is today accepted to play a key role for transport of agrochemicals in cohesive soils. The spatial distribution of worm burrows in the landscape may, furthermore, exert crucial control on rainfall runoff response and sediment yields at the hillslope and catchment scales. However, even if the population of connected biopores/macropores is known in soil we struggle in predicting onset, timing and strength of preferential flow events. Preferential flow is an intermittent, threshold phenomenon. Onset and intensity seems to be determined by the strength of the rainfall forcing and the wetness state of the soil. Furthermore, burrows of deep digging aenecic earthworms can ? even when being abandoned ? persist over decades as suggested by accumulation of clay particles or even radio nuclides. Thus, these structures ?survive? severe rainfall and subsurface flow events and still remain functional in the hydrological system. Why is it sometimes ?favourable? to take flow paths of minimum flow resistance and sometimes not? Why do these flow paths/ structures persist such a long time? Following Kleidon and Schimansky (2008) we suggest that a thermodynamic perspective ? looking at soil water flow as dissipative process in an open, non equilibrium thermodynamic system ? may help unrevealing these questions. However, we suggest a complementary perspective on soil water flow focusing rather on entropy production but on dissipation of Helmholtz free energy. Thermodynamic equilibrium is a state of minimum free energy. The latter is determined by potential energy and capillary energy in soil, which in turn strongly depends on soil moisture, pore size distribution and depth to groundwater. The objective of this study is threefold. First, we will introduce the necessary theoretical background. Second we suggest ? based on simulations with a physically based hydrological model ? that water flow in connected preferential pathways assures a faster relaxation towards thermodynamic equilibrium through a faster drainage of ?excess water? and a faster redistribution of ?capillary water? within the soil. The latter process is of prime importance in case of cohesive soils where the pore size distribution is dominated by medium and small pores. Third, an application of a physically based hydrological model to predict water flow and runoff response from a pristine catchment in the Chilenean Andes underpins this hypothesis. Behavioral model structures that allow a good match of the observed hydrographs turned out to be most efficient in dissipating free energy by means of preferential flow. It seems that a population of connected preferential pathways is favourable both for resilience and stability of these soils during extreme events and to retain water resources for the ecosystem at the same time. We suggest that this principle of ?maximum energy dissipation? may on the long term help us to better understand why soil structures remain stable, threshold nature of preferential as well as offer a means to further reduce model structural uncertainty. Bloeschl, G. 2006. Idle thoughts on a unifying theory of catchment Hydrology. Geophysical Research Abstracts, Vol. 8, 10677, 2006 SRef-ID: 1607-7962/gra/EGU06-A-10677 European Geosciences Union 2006 Kleidon, A., and S. Schymanski (2008), Thermodynamics and optimality of the water budget on land: A review, Geophys. Res. Lett., 35, L20404, doi:10.1029/ 2008GL035393.

How Darcy's Law sparked various fields of subsurface hydrology.

NASA Astrophysics Data System (ADS)

de Rooij, Gerrit H.

2016-04-01

Henry Darcy built the drinking water supply system of the French city of Dijon in the mid-19th century. In doing so, he developed an interest in the flow of water through sands, and, experimented with water flow in a vertical cylinder filled with different sands. He found Darcy's Law in this way, and until this day it is the cornerstone of the theory of water flow in porous media. Darcy's Law was quickly adopted for calculating groundwater flow, which blossomed after the introduction of a few very useful simplifying assumptions that permitted a host of analytical solutions to groundwater problems, including flows toward pumped drinking water wells and toward drain tubes. In soil hydrology, Darcy's Law itself required modification to facilitate its application for different soil water contents. The understanding of the relationship between the potential energy of soil water and the soil water content emerged early in the 20th century. The mathematical formalization of the consequences for the flow rate and storage change of soil water was established in the 1930s, but only after the 1970s did computers become powerful enough to tackle unsaturated flows head-on. In combination with crop growth models, this allowed Darcy-based models to aid in the setup of irrigation practices and to optimize drainage designs. In the past decades, spatial variation of the hydraulic properties of aquifers and soils has been shown to affect the transfer of solutes from soils to groundwater and from groundwater to surface water. All this emerged from a law derived from a few experiments on a cylinder filled with sand in the 1850s. The poster tracks this development of groundwater hydrology and soil water hydrology through seminal contributions over the past 160 years.

Integration of multi-sensor data to measure soil surface changes

NASA Astrophysics Data System (ADS)

Eltner, Anette; Schneider, Danilo

2016-04-01

Digital elevation models (DEM) of high resolution and accuracy covering a suitable sized area of interest can be a promising approach to help understanding the processes of soil erosion. Thereby, the plot under investigation should remain undisturbed. The fragile marl landscape in Andalusia (Spain) is especially prone to soil detachment and transport with unique sediment connectivity characteristics due to the soil properties and climatic conditions. A 600 m² field plot is established and monitored during three field campaigns (Sep. 2013, Nov. 2013 and Feb. 2014). Unmanned aerial vehicle (UAV) photogrammetry and terrestrial laser scanning (TLS) are suitable tools to generate high resolution topography data that describe soil surface changes at large field plots. Thereby, the advantages of both methods are utilised in a synergetic manner. On the one hand, TLS data is assumed to comprise a higher reliability regarding consistent error behaviour than DEMs derived from overlapping UAV images. Therefore, global errors (e.g. dome effect) and local errors (e.g. DEM blunders due to erroneous image matching) within the UAV data are assessed with the DEMs produced by TLS. Furthermore, TLS point clouds allow for fast and reliable filtering of vegetation spots, which is not as straightforward within the UAV data due to known image matching problems in areas displaying plant cover. On the other hand, systematic DEM errors linked to TLS are detected and possibly corrected utilising the DEMs reconstructed from overlapping UAV images. Furthermore, TLS point clouds are filtered corresponding to the degree of point quality, which is estimated from parameters of the scan geometry (i.e. incidence angle and footprint size). This is especially relevant for this study because the area of interest is located at gentle hillslopes that are prone to soil erosion. Thus, the view of the scanning device onto the surface results in an adverse angle, which is solely slightly improved by the usage of a 4 m high tripod. Surface roughness is considered as a further parameter to evaluate the TLS point quality. The filtering tool allows for choosing each data point either from the TLS or UAV data corresponding to the data acquisition geometry and surface properties. The filtered points are merged into one point cloud, which is finally processed to reduce remaining data noise. DEM analysis reveals a continuous decrease of soil surface roughness after tillage, the reappearance of former wheel tracks and local patterns of erosion as well as accumulation.

Analysis of up-flow aerated biological activated carbon filter technology in drinking water treatment.

PubMed

Lu, Shaoming; Liu, Jincui; Li, Shaowen; Biney, Elizabeth

2013-01-01

Problems have been found in the traditional post-positioned down-flow biological activated carbon filter (DBACF), such as microorganism leakage and low biodegradability. A pilot test was carried out to place a BACF between the sediment tank and the sand filter; a new technology of dual media up-flow aerated biological activated carbon filter (UBACF) was developed. Results showed that in terms of the new process, the up-flow mode was better than the down-flow. Compared with the DBACF, the problem of microorganism leakage could be well resolved with the UBACF process by adding disinfectant before the sand filtration, and a similar adsorption effect could be obtained. For the tested raw water, the COD(Mn) and NH3-N removal rate was 54.6% and 85.0%, respectively, similar to the waterworks with the DBACF process. The UBACF greatly enhanced oxygen supply capability and mass transfer rate via aeration, and the NH3-N removal ability was significantly improved from 1.5 mg/L to more than 3 mg/L. Influent to the UBACF with higher turbidity could be coped with through the primary filtration of the ceramisite layer combined with fluid-bed technology, which gave the carbon bed a low-turbidity environment of less than 1.0 NTU. The backwashing parameters and carbon abrasion rate of the two processes were almost the same.

[Humidification assessment of four heat and moisture exchanger filters according to ISO 9360: 2000 standard].

PubMed

Lannoy, D; Décaudin, B; Resibois, J-P; Barrier, F; Wierre, L; Horrent, S; Batt, C; Moulront, S; Odou, P

2008-02-01

This work consisted of the assessment of humidification parameters and flow resistance for different heat and moisture exchanger filters (HMEF) used in intensive care unit. Four electrostatic HMEF were assessed: Hygrobac S (Tyco); Humidvent compact S (Teleflex); Hygrovent S/HME (Medisize-Dräger); Clear-Therm+HMEF (Intersurgical). Humidification parameters (loss of water weight, average absolute moisture [AAM], absolute variation of moisture) have been evaluated on a bench-test in conformity with the ISO 9360: 2000 standard, for 24h with the following ventilatory settings: tidal volume at 500 ml, respiratory rate at 15 c/min, and inspiration/expiration ratio at 1:1. The flow resistance of HMEFs assessed using the pressure drop method was measured before and after 24h of humidification for three increasing air flows of 30, 60, and 90 l/min. All the HMEFs allowed satisfactory level of humidification exceeding 30 mgH(2)O/l. The less powerful remained the Clear-Therm. Concerning HMEFs flow resistance, results showed a pressure drop slightly more important for the Hygrobac S filter as compared with other filters. This test showed differences between the HMEFs for both humidification and resistance parameters. When compared to the new version of the standards, HMEFs demonstrated their reliability. However, evolution of humidification and flow resistance characteristics over 24h showed a structural degradation of HMEFs, limiting their use over a longer period.

Influences of quaternary climatic changes on processes of soil development on desert loess deposits of the Cima volcanic field, California

USGS Publications Warehouse

McFadden, L.D.; Wells, S.G.; Dohrenwend, J.C.

1986-01-01

Soils formed in loess are evidence of both relict and buried landscapes developed on Pliocene-to-latest Pleistocene basalt flows of the Cima volcanic field in the eastern Mojave Desert, California. The characteristics of these soils change systematically and as functions of the age and surface morphology of the lava flow. Four distinct phases of soil development are recognized: phase 1 - weakly developed soils on flows less than 0.18 M.y. old; phase 2 - strongly developed soils with thick argillic horizons on 0.18 - 0.7 M.y. old flows; phase 3 - strongly developed soils with truncated argillic horizons massively impregnated by carbonate on 0.7 to 1.1 M.y. old flows; and phase 4 - degraded soils with petrocalcic rubble on Pliocene flows. A critical aspect of the development of stage 1 soils is the evolution of a vesicular A horizon which profoundly affects the infiltration characteristics of the loess parent materials. Laboratory studies show that secondary gypsum and possibly other salt accumulation probably occurred during the period of phase 1 soil development. Slight reddening of the interiors of peds from vesicular-A horizons of phase 1 soils and presence of weakly developed B horizons indicates a slight degree of in situ chemical alteration. However, clay and Fe oxide contents of these soils show that these constituents, as well as carbonates and soluble salts, are incorporated as eolian dust. In contrast to phase 1 soils, chemical and mineralogical analysis of argillic horizons of phase 2 soils indicate proportionally greater degrees of in-situ chemical alteration. These data, the abundant clay films, and the strong reddening in the thick argillic horizons suggest that phase 2 and phase 3 soils formed during long periods of time and periodically were subjected to leaching regimes more intense than those that now exist. Flow-age data and soil-stratigraphic evidence also indicate that several major loess-deposition events occurred during the past ??? 1.0 M.y. Loess events are attributed to past changes in climate, such as the Pleistocene-to-Holocene climatic change, that periodically caused regional desiccation of pluvial lakes, reduction of vegetational density, and exposure of loose, unconsolidated fine materials. During times of warmer interglacial climates, precipitation infiltrates to shallower depths than during glacial periods. Extensive, saline playas which developed in the Mojave Desert during the Holocene are a likely source of much of the carbonates and soluble salts that are accumulating at shallow depths both in phase 1 soils and in the formerly noncalcareous, nongypsiferous argillic horizons of phase 2 and 3 soils. ?? 1986.

Hydrocyclone/Filter for Concentrating Biomarkers from Soil

NASA Technical Reports Server (NTRS)

Ponce, Adrian; Obenhuber, Donald

2008-01-01

The hydrocyclone-filtration extractor (HFE), now undergoing development, is a simple, robust apparatus for processing large amounts of soil to extract trace amounts of microorganisms, soluble organic compounds, and other biomarkers from soil and to concentrate the extracts in amounts sufficient to enable such traditional assays as cell culturing, deoxyribonucleic acid (DNA) analysis, and isotope analysis. Originally intended for incorporation into a suite of instruments for detecting signs of life on Mars, the HFE could also be used on Earth for similar purposes, including detecting trace amounts of biomarkers or chemical wastes in soils.

[Characters of infiltration and preferential flow of black soil in Northeast China under different tillage patterns].

PubMed

Li, Wen-Feng; Zhang, Xiao-Ping; Liang, Ai-Zhen; Shen, Yan; Shi, Xiu-Huan; Luo, Jin-Ming; Yang, Xue-Ming

2008-07-01

By using dye tracer and double-ring infiltrometer techniques, the characters of infiltration and preferential flow of black soil under no-tillage (NT) and fall moldboard plow (MP) were compared after six years continuous management. The results showed that the infiltration rate was higher under NT than under MP. When the infiltration reached steady, the infiltration rate and accumulative infiltration capacity under NT were 1.35 and 1.44 times as high as those under MP, respectively. The penetration depth of methylene blue reached a depth of 43 cm in NT soil, being 16 cm deeper than that in MP soil. Comparing with MP soil, NT soil had better development of pore structure and more biological pores, and presented better preferential flow character, which were of importance for water infiltration and soil and water conservation.

Least Median of Squares Filtering of Locally Optimal Point Matches for Compressible Flow Image Registration

PubMed Central

Castillo, Edward; Castillo, Richard; White, Benjamin; Rojo, Javier; Guerrero, Thomas

2012-01-01

Compressible flow based image registration operates under the assumption that the mass of the imaged material is conserved from one image to the next. Depending on how the mass conservation assumption is modeled, the performance of existing compressible flow methods is limited by factors such as image quality, noise, large magnitude voxel displacements, and computational requirements. The Least Median of Squares Filtered Compressible Flow (LFC) method introduced here is based on a localized, nonlinear least squares, compressible flow model that describes the displacement of a single voxel that lends itself to a simple grid search (block matching) optimization strategy. Spatially inaccurate grid search point matches, corresponding to erroneous local minimizers of the nonlinear compressible flow model, are removed by a novel filtering approach based on least median of squares fitting and the forward search outlier detection method. The spatial accuracy of the method is measured using ten thoracic CT image sets and large samples of expert determined landmarks (available at www.dir-lab.com). The LFC method produces an average error within the intra-observer error on eight of the ten cases, indicating that the method is capable of achieving a high spatial accuracy for thoracic CT registration. PMID:22797602

Field experiment and numerical simulation of coupling non-Darcy flow caused by curtain and pumping well in foundation pit dewatering

NASA Astrophysics Data System (ADS)

Wang, Jianxiu; Liu, Xiaotian; Wu, Yuanbin; Liu, Shaoli; Wu, Lingao; Lou, Rongxiang; Lu, Jiansheng; Yin, Yao

2017-06-01

High-velocity non-Darcy flow produced larger drawdown than Darcy flow under the same pumping rate. When the non-Darcy flow caused by curtain met non-Darcy flow caused by pumping wells, superposition and amplification effect occurred in the coupling area, the non-Darcy flow was defined as coupling non-Darcy flow. The coupling non-Darcy flow can be produced and controlled using different combination of curtain and pumping wells in foundation pit dewatering to obtain the maximum drawdown using the minimum pumping rate. The Qianjiang Century City Station foundation pit of Hangzhou subway, China, was selected as background. Field experiments were performed to observe the coupling non-Darcy flow in round gravel. A generalized conceptual model was established to study the coupling effect under different combination of curtain and pumping wells. Numerical simulations of the coupling non-Darcy flow in foundation pit dewatering were carried out based on the Forchheimer equation. The non-Darcy flow area and flow velocity were influenced by the coupling effect. Short filter tube, large pumping rate, small horizontal distance between filter tube and diaphragm wall, and small vertical distance between the filter tube and confined aquifer roof effectively strengthened the coupling effect and obtained a large drawdown. The pumping wells installed close to a curtain was an intentional choice designed to create coupling non-Darcy flow and obtain the maximize drawdown. It can be used in the dewatering of a long and narrow foundation pit, such as a subway foundation pit.

An overland flow sampler for use in vegetative filters

Treesearch

D. Eisenhauer; M. Helmers; J. Brothers; M. Dosskey; T. Franti; A. Boldt; B. Strahm

2002-01-01

Vegetative filters (VF) are used to remove contaminants from agricultural runoff and improve surface water quality. Techniques are needed to quantify the performance of VF in realistic field settings. The goal of this project was to develop and test a relatively simple and low cost method for sampling overland flow in a VF. The 0.3 m wide sampler has the capacity to...

40 CFR Table 3 to Subpart Ec of... - Operating Parameters To Be Monitored and Minimum Measurement and Recording Frequencies

Code of Federal Regulations, 2011 CFR

2011-07-01

... scrubber followed by fabric filter Wet scrubber Dry scrubber followed by fabric filter and wet scrubber... flow rate Hourly 1×hour ✔ ✔ Minimum pressure drop across the wet scrubber or minimum horsepower or amperage to wet scrubber Continuous 1×minute ✔ ✔ Minimum scrubber liquor flow rate Continuous 1×minute...

Comparison of a new inorganic membrane filter (Anopore) with a track-etched polycarbonate membrane filter (Nuclepore) for direct counting of bacteria.

PubMed Central

Jones, S E; Ditner, S A; Freeman, C; Whitaker, C J; Lock, M A

1989-01-01

Bacterial counts obtained by using a new Anopore inorganic membrane filter were 21 to 33% higher than those obtained by using a Nuclepore polycarbonate membrane filter. In addition, the inorganic filter had higher flow rates, permitting lower vacuum pressures to be used, while the intrinsically flat, rigid surface resulted in easier focusing and sharp definition of bacteria across the whole field of view. Images PMID:2655539

Preliminary Engineering Design Package for the Basin A Neck Groundwater Intercept and Treatment System Interim Response Action

DTIC Science & Technology

1989-02-01

INDICATOR pPOST-FILTERED VITER RPUESIC POST-FILTRATION POLYMER SOLUTION MCUUM BREAKER FILTRATION POLYMER D*+RENTALkL PRESSURE SWITCH FEED PUMPS POLYMER...differential pressure switch signals the need for backwash of the operating filter. At this time, flow is S automatically switched to the standby filter...filter is undergoing backwash or on standby. High differential pressure across the filter bed, as sensed by a differential pressure switch , signals

Hydrologic data assimilation with a hillslope-scale-resolving model and L band radar observations: Synthetic experiments with the ensemble Kalman filter

NASA Astrophysics Data System (ADS)

Flores, Alejandro N.; Bras, Rafael L.; Entekhabi, Dara

2012-08-01

Soil moisture information is critical for applications like landslide susceptibility analysis and military trafficability assessment. Existing technologies cannot observe soil moisture at spatial scales of hillslopes (e.g., 100 to 102 m) and over large areas (e.g., 102 to 105 km2) with sufficiently high temporal coverage (e.g., days). Physics-based hydrologic models can simulate soil moisture at the necessary spatial and temporal scales, albeit with error. We develop and test a data assimilation framework based on the ensemble Kalman filter for constraining uncertain simulated high-resolution soil moisture fields to anticipated remote sensing products, specifically NASA's Soil Moisture Active-Passive (SMAP) mission, which will provide global L band microwave observation approximately every 2-3 days. The framework directly assimilates SMAP synthetic 3 km radar backscatter observations to update hillslope-scale bare soil moisture estimates from a physics-based model. Downscaling from 3 km observations to hillslope scales is achieved through the data assimilation algorithm. Assimilation reduces bias in near-surface soil moisture (e.g., top 10 cm) by approximately 0.05 m3/m3and expected root-mean-square errors by at least 60% in much of the watershed, relative to an open loop simulation. However, near-surface moisture estimates in channel and valley bottoms do not improve, and estimates of profile-integrated moisture throughout the watershed do not substantially improve. We discuss the implications of this work, focusing on ongoing efforts to improve soil moisture estimation in the entire soil profile through joint assimilation of other satellite (e.g., vegetation) and in situ soil moisture measurements.

Quantifying the Effects of Biofilm on the Hydraulic Properties of Unsaturated Soils

NASA Astrophysics Data System (ADS)

Volk, E.; Iden, S.; Furman, A.; Durner, W.; Rosenzweig, R.

2017-12-01

Quantifying the effects of biofilms on hydraulic properties of unsaturated soils is necessary for predicting water and solute flow in soil with extensive microbial presence. This can be relevant to bioremediation processes, soil aquifer treatment and effluent irrigation. Previous works showed a reduction in the hydraulic conductivity and an increase in water content due to the addition of biofilm analogue materials. The objective of this research is to quantify soil hydraulic properties of unsaturated soil (water retention and hydraulic conductivity) using real soil biofilm. In this work, Hamra soil was incubated with Luria Broth (LB) and biofilm-producing bacteria (Pseudomonas Putida F1). Hydraulic conductivity and water retention were measured by the evaporation method, Dewpoint method and a constant head permeameter. Biofilm was quantified using viable counts and the deficit of TOC. The results show that the presence of biofilms increases soil retention in the `dry' range of the curve and reduces the hydraulic conductivity (see figure). This research shows that biofilms may have a non-negligible effect on flow and transport in unsaturated soils. These findings contribute to modeling water flow in biofilm amended soil.

The preferential flow of soil: A widespread phenomenon in pedological perspectives

NASA Astrophysics Data System (ADS)

Zhang, Yinghu; Zhang, Mingxiang; Niu, Jianzhi; Zheng, Haijin

2016-06-01

The article provides an overview of studies about the preferential flow phenomenon. This phenomenon is one of the types of the transportation of water solution through the soil profile by preferential channels (pathways) with a relatively high speed and with a slight change in the chemical composition of the solution. Interest in this phenomenon has risen sharply in the last two decades due to the observed fast transportation of contaminants from soil surface into groundwater level. On the basis of the literature data, the authors give the definition of this phenomenon, consider its types, degree, features, mechanisms, methods and models and research perspectives, in particular the interaction between preferential flow and soil matrix flow. The article considers the aspects of the movement of soil water carrying heavy metals and pesticides; hence, it concerns the protection of environment and people's health. It provides the thorough review of the studies on the preferential flow, and describes the research directions and their development.

Filtered Mass Density Function for Design Simulation of High Speed Airbreathing Propulsion Systems

NASA Technical Reports Server (NTRS)

Givi, P.; Madnia, C. K.; Gicquel, L. Y. M.; Sheikhi, M. R. H.; Drozda, T. G.

2002-01-01

The objective of this research is to improve and implement the filtered mass density function (FDF) methodology for large eddy simulation (LES) of high speed reacting turbulent flows. NASA is interested in the design of various components involved in air breathing propulsion systems such as the scramjet. There is a demand for development of robust tools that can aid in the design procedure. The physics of high speed reactive flows is rich with many complexities. LES is regarded as one of the most promising means of simulating turbulent reacting flows.

Final Report for Geometric Observers and Particle Filtering for Controlled Active Vision

DTIC Science & Technology

2016-12-15

code) 15-12-2016 Final Report 01Sep06 - 09May11 Final Report for Geometric Observers & Particle Filtering for Controlled Active Vision 49414-NS.1Allen...Observers and Particle Filtering for Controlled Active Vision by Allen R. Tannenbaum School of Electrical and Computer Engineering Georgia Institute of...7 2.2.4 Conformal Area Minimizing Flows . . . . . . . . . . . . . . . . . . . . . . . 8 2.3 Particle Filters

Subsurface Hydrologic Processes Revealed by Time-lapse GPR in Two Contrasting Soils in the Shale Hills CZO

NASA Astrophysics Data System (ADS)

Guo, L.; Lin, H.; Nyquist, J.; Toran, L.; Mount, G.

2017-12-01

Linking subsurface structures to their functions in determining hydrologic processes, such as soil moisture dynamics, subsurface flow patterns, and discharge behaviours, is a key to understanding and modelling hydrological systems. Geophysical techniques provide a non-invasive approach to investigate this form-function dualism of subsurface hydrology at the field scale, because they are effective in visualizing subsurface structure and monitoring the distribution of water. In this study, we used time-lapse ground-penetrating radar (GPR) to compare the hydrologic responses of two contrasting soils in the Shale Hills Critical Zone Observatory. By integrating time-lapse GPR with artificial water injection, we observed distinct flow patterns in the two soils: 1) in the deep Rushtown soil (over 1.5 m depth to bedrock) located in a concave hillslope, a lateral preferential flow network extending as far as 2 m downslope was identified above a less permeable layer and via a series of connected macropores; whereas 2) in the shallow Weikert soil ( 0.3 m depth to saprock) located in a planar hillslope, vertical infiltration into the permeable fractured shale dominated the flow field, while the development of lateral preferential flow along the hillslope was restrained. At the Weikert soil site, the addition of brilliant blue dye to the water injection followed by in situ excavation supported GPR interpretation that only limited lateral preferential flow formed along the soil-saprock interface. Moreover, seasonally repeated GPR surveys indicated different patterns of profile moisture distribution in the two soils that in comparison with the dry season, a dense layer within the BC horizon in the deep Rushtown soil prevented vertical infiltration in the wet season, leading to the accumulation of soil moisture above this layer; whereas, in the shallow Weikert soil, water infiltrated into saprock in wet seasons, building up water storage within the fractured bedrock (i.e., the rock moisture). Results of this study demonstrated the strong interplay between soil structures and subsurface hydrologic behaviors, and time-lapse GPR is an effective method to establish such a relationship under the field conditions.

Hydrodynamics of microbial filter feeding

PubMed Central

Asadzadeh, Seyed Saeed; Dölger, Julia; Walther, Jens H.; Andersen, Anders

2017-01-01

Microbial filter feeders are an important group of grazers, significant to the microbial loop, aquatic food webs, and biogeochemical cycling. Our understanding of microbial filter feeding is poor, and, importantly, it is unknown what force microbial filter feeders must generate to process adequate amounts of water. Also, the trade-off in the filter spacing remains unexplored, despite its simple formulation: A filter too coarse will allow suitably sized prey to pass unintercepted, whereas a filter too fine will cause strong flow resistance. We quantify the feeding flow of the filter-feeding choanoflagellate Diaphanoeca grandis using particle tracking, and demonstrate that the current understanding of microbial filter feeding is inconsistent with computational fluid dynamics (CFD) and analytical estimates. Both approaches underestimate observed filtration rates by more than an order of magnitude; the beating flagellum is simply unable to draw enough water through the fine filter. We find similar discrepancies for other choanoflagellate species, highlighting an apparent paradox. Our observations motivate us to suggest a radically different filtration mechanism that requires a flagellar vane (sheet), something notoriously difficult to visualize but sporadically observed in the related choanocytes (sponges). A CFD model with a flagellar vane correctly predicts the filtration rate of D. grandis, and using a simple model we can account for the filtration rates of other microbial filter feeders. We finally predict how optimum filter mesh size increases with cell size in microbial filter feeders, a prediction that accords very well with observations. We expect our results to be of significance for small-scale biophysics and trait-based ecological modeling. PMID:28808016

Hydrodynamics of microbial filter feeding.

PubMed

Nielsen, Lasse Tor; Asadzadeh, Seyed Saeed; Dölger, Julia; Walther, Jens H; Kiørboe, Thomas; Andersen, Anders

2017-08-29

Microbial filter feeders are an important group of grazers, significant to the microbial loop, aquatic food webs, and biogeochemical cycling. Our understanding of microbial filter feeding is poor, and, importantly, it is unknown what force microbial filter feeders must generate to process adequate amounts of water. Also, the trade-off in the filter spacing remains unexplored, despite its simple formulation: A filter too coarse will allow suitably sized prey to pass unintercepted, whereas a filter too fine will cause strong flow resistance. We quantify the feeding flow of the filter-feeding choanoflagellate Diaphanoeca grandis using particle tracking, and demonstrate that the current understanding of microbial filter feeding is inconsistent with computational fluid dynamics (CFD) and analytical estimates. Both approaches underestimate observed filtration rates by more than an order of magnitude; the beating flagellum is simply unable to draw enough water through the fine filter. We find similar discrepancies for other choanoflagellate species, highlighting an apparent paradox. Our observations motivate us to suggest a radically different filtration mechanism that requires a flagellar vane (sheet), something notoriously difficult to visualize but sporadically observed in the related choanocytes (sponges). A CFD model with a flagellar vane correctly predicts the filtration rate of D. grandis , and using a simple model we can account for the filtration rates of other microbial filter feeders. We finally predict how optimum filter mesh size increases with cell size in microbial filter feeders, a prediction that accords very well with observations. We expect our results to be of significance for small-scale biophysics and trait-based ecological modeling.

Biofilm effect on soil hydraulic properties: Experimental investigation using soil-grown real biofilm

NASA Astrophysics Data System (ADS)

Volk, Elazar; Iden, Sascha C.; Furman, Alex; Durner, Wolfgang; Rosenzweig, Ravid

2016-08-01

Understanding the influence of attached microbial biomass on water flow in variably saturated soils is crucial for many engineered flow systems. So far, the investigation of the effects of microbial biomass has been mainly limited to water-saturated systems. We have assessed the influence of biofilms on the soil hydraulic properties under variably saturated conditions. A sandy soil was incubated with Pseudomonas Putida and the hydraulic properties of the incubated soil were determined by a combination of methods. Our results show a stronger soil water retention in the inoculated soil as compared to the control. The increase in volumetric water content reaches approximately 0.015 cm3 cm-3 but is only moderately correlated with the carbon deficit, a proxy for biofilm quantity, and less with the cell viable counts. The presence of biofilm reduced the saturated hydraulic conductivity of the soil by up to one order of magnitude. Under unsaturated conditions, the hydraulic conductivity was only reduced by a factor of four. This means that relative water conductance in biofilm-affected soils is higher compared to the clean soil at low water contents, and that the unsaturated hydraulic conductivity curve of biofilm-affected soil cannot be predicted by simply scaling the saturated hydraulic conductivity. A flexible parameterization of the soil hydraulic functions accounting for capillary and noncapillary flow was needed to adequately describe the observed properties over the entire wetness range. More research is needed to address the exact flow mechanisms in biofilm-affected, unsaturated soil and how they are related to effective system properties.

Mercury dynamics in relation to dissolved organic carbon concentration and quality during high flow events in three northeastern U.S. streams

USGS Publications Warehouse

Dittman, Jason A.; Shanley, James B.; Driscoll, Charles T.; Aiken, George R.; Chalmers, Ann T.; Towse, Janet E.; Selvendiran, Pranesh

2010-01-01

Mercury (Hg) contamination is widespread in remote areas of the northeastern United States. Forested uplands have accumulated a large reservoir of Hg in soil from decades of elevated anthropogenic deposition that can be released episodically to stream water during high flows. The objective of this study was to evaluate spatial and temporal variations in stream water Hg species and organic matter fractions over a range of hydrologic conditions in three forested upland watersheds (United States). Mercury and organic matter concentrations increased with discharge at all three sites; however, the partitioning of Hg fractions (dissolved versus particulate) differed among sites and seasons. Associated with increased discharge, flow paths shifted from mineral soil under base flow to upper soil horizons. As flow paths shifted, greater concentrations of dissolved organic carbon (DOC) richer in aromatic substances were flushed from upper soil horizons to stream water. The hydrophobic organic matter associated with humic material from upper soils appears to have had a greater capacity to bind Hg. Because of the strong correlation between Hg and DOC, we hypothesize that there was a concurrent shift in the source of Hg with DOC from lower mineral soil to upper soil horizons. Our study suggests that stream discharge is an effective predictor of dissolved total Hg flux.

Soil slips and debris flows on terraced slopes

NASA Astrophysics Data System (ADS)

Crosta, G. B.; Dal Negro, P.; Frattini, P.

Terraces cover large areas along the flanks of many alpine and prealpine valleys. Soil slips and soil slips-debris flows are recurrent phenomena along terraced slopes. These landslides cause damages to people, settlements and cultivations. This study investigates the processes related to the triggering of soil slip-debris flows in these settings, analysing those occurred in Valtellina (Central Alps, Italy) on November 2000 after heavy prolonged rainfalls. 260 landslides have been recognised, mostly along the northern valley flank. About 200 soil slips and slumps occurred in terraced areas and a third of them evolved into debris flows. Field work allowed to recognise the settings at soil slip-debris flow source areas. Landslides affected up to 2.5 m of glacial, fluvioglacial and anthropically reworked deposits overlying metamorphic basement. Laboratory and in situ tests allowed to characterise the geotechnical and hydraulic properties of the terrains involved in the initial failure. Several stratigraphic and hydrogeologic factors have been individuated as significant in determining instabilities on terraced slopes. They are the vertical changes of physical soil properties, the presence of buried hollows where groundwater convergence occurs, the rising up of perched groundwater tables, the overflow and lateral infiltration from superficial drainage network, the runoff concentration by means of pathways and the insufficient drainage of retaining walls.

Model simulation and experiments of flow and mass transport through a nano-material gas filter

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Xiaofan; Zheng, Zhongquan C.; Winecki, Slawomir

2013-11-01

A computational model for evaluating the performance of nano-material packed-bed filters was developed. The porous effects of the momentum and mass transport within the filter bed were simulated. For the momentum transport, an extended Ergun-type model was employed and the energy loss (pressure drop) along the packed-bed was simulated and compared with measurement. For the mass transport, a bulk dsorption model was developed to study the adsorption process (breakthrough behavior). Various types of porous materials and gas flows were tested in the filter system where the mathematical models used in the porous substrate were implemented and validated by comparing withmore » experimental data and analytical solutions under similar conditions. Good agreements were obtained between experiments and model predictions.« less

Mechanistic failure mode investigation and resolution of parvovirus retentive filters.

PubMed

LaCasse, Daniel; Lute, Scott; Fiadeiro, Marcus; Basha, Jonida; Stork, Matthew; Brorson, Kurt; Godavarti, Ranga; Gallo, Chris

2016-07-08

Virus retentive filters are a key product safety measure for biopharmaceuticals. A simplistic perception is that they function solely based on a size-based particle removal mechanism of mechanical sieving and retention of particles based on their hydrodynamic size. Recent observations have revealed a more nuanced picture, indicating that changes in viral particle retention can result from process pressure and/or flow interruptions. In this study, a mechanistic investigation was performed to help identify a potential mechanism leading to the reported reduced particle retention in small virus filters. Permeate flow rate or permeate driving force were varied and analyzed for their impact on particle retention in three commercially available small virus retentive filters. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 32:959-970, 2016. © 2016 American Institute of Chemical Engineers.

[The aspiratory resistance and filtration penetration of N95 filtering-facepiece respirators used widely in China].

PubMed

Wang, Xinyan; Shi, Tingming; Lu, Wei; Qin, Shaoxian; Liu, Yuewei; Tao, Ying; Zhang, Hongge; Chen, Weihong

2015-01-01

The objective of this study was to investigate the aspiratory resistance, filtration penetration and their influence factors of N95 filtering-facepiece respirators used widely in China. The total of 6 brands and 21 models of N95 filtering-facepiece respirators which are certified and big sales on the market. The aspiratory resistance and filtration efficiency filter penetration were measured while air pump ran from 10 L/min to 100 L/min using differential pressure gauge and the PortaCount, respectively. The filtration penetrations for 2 of the 21 models were lower than 95%, and the qualified rate for all models was 90.47%. The filtration penetrations gradually decreased when ventilation flow of air pump increased. The negative correlation was observed between filtration penetration and ventilation flow (r(2) = 0.711, P < 0.05). The resistances of all 21 models of N95 respirators met the requirements of the national standard. The aspiratory resistance started to elevate with the increasing of ventilation flow, and a positive correlation between both (r(2) = 0.878, P < 0.05). Significant differences of filtration penetration and aspiratory resistance were observed among between different brands (P < 0.05) although no differences of filtration penetration existed among different models of one brand (P > 0.05). But the differences of the aspiratory resistance among different models of one brand were statistically significant (P < 0.05). The aspiratory resistances of all N95 filtering-facepiece respirators used in this study met the requirements of the national standard. And the qualified ratio of filtration penetration of all models was higher than 90%. The influencing factors of aspiratory resistance included materials, size and ventilation flow. And influencing factors for filtration penetration were materials and ventilation flow.

On performing of interference technique based on self-adjusting Zernike filters (SA-AVT method) to investigate flows and validate 3D flow numerical simulations

NASA Astrophysics Data System (ADS)

Pavlov, Al. A.; Shevchenko, A. M.; Khotyanovsky, D. V.; Pavlov, A. A.; Shmakov, A. S.; Golubev, M. P.

2017-10-01

We present a method for and results of determination of the field of integral density in the structure of flow corresponding to the Mach interaction of shock waves at Mach number M = 3. The optical diagnostics of flow was performed using an interference technique based on self-adjusting Zernike filters (SA-AVT method). Numerical simulations were carried out using the CFS3D program package for solving the Euler and Navier-Stokes equations. Quantitative data on the distribution of integral density on the path of probing radiation in one direction of 3D flow transillumination in the region of Mach interaction of shock waves were obtained for the first time.

Validated Metrics of Quick Flow Improve Assessments of Streamflow Generation Processes at the Long-Term Sleepers River Research Site

NASA Astrophysics Data System (ADS)

Sebestyen, S. D.; Shanley, J. B.

2015-12-01

There are multiple approaches to quantify quick flow components of streamflow. Physical hydrograph separations of quick flow using recession analysis (RA) are objective, reproducible, and easily calculated for long-duration streamflow records (years to decades). However, this approach has rarely been validated to have a physical basis for interpretation. In contrast, isotopic hydrograph separation (IHS) and end member mixing analysis using multiple solutes (EMMA) have been used to identify flow components and flowpath routing through catchment soils. Nonetheless, these two approaches are limited by data from limited and isolated periods (hours to weeks) during which more-intensive grab samples were analyzed. These limitations oftentimes make IHS and EMMA difficult to generalize beyond brief windows of time. At the Sleepers River Research Watershed (SRRW) in northern Vermont, USA, we have data from multiple snowmelt events over a two decade period and from multiple nested catchments to assess relationships among RA, IHS, and EMMA. Quick flow separations were highly correlated among the three techniques, which shows links among metrics of quick flow, water sources, and flow path routing in a small (41 ha), forested catchment (W-9) The similarity in responses validates a physical interpretation for a particular RA approach (the Ekhardt recursive RA filter). This validation provides a new tool to estimate new water inputs and flowpath routing for more and longer periods when chemical or isotopic tracers may not have been measured. At three other SRRW catchments, we found similar strong correlations among the three techniques. Consistent responses across four catchments provide evidence to support other research at the SRRW that shows that runoff generation mechanisms are similar despite differences in catchment sizes and land covers.

Validation of the stomatal flux approach for the assessment of ozone visible injury in young forest trees. Results from the TOP (transboundary ozone pollution) experiment at Curno, Italy.

PubMed

Gerosa, G; Marzuoli, R; Desotgiu, R; Bussotti, F; Ballarin-Denti, A

2009-05-01

This paper summarises some of the main results of a two-year experiment carried out in an Open-Top Chambers facility in Northern Italy. Seedlings of Populus nigra, Fagus sylvatica, Quercus robur and Fraxinus excelsior have been subjected to different ozone treatments (charcoal-filtered and non-filtered air) and soil moisture regimes (irrigated and non-irrigated plots). Stomatal conductance models were applied and parameterised under South Alpine environmental conditions and stomatal ozone fluxes have been calculated. The flux-based approach provided a better performance than AOT40 in predicting the onset of foliar visible injuries. Critical flux levels, related to visible leaf injury, are proposed for P. nigra and F. sylvatica (ranging between 30 and 33 mmol O(3) m(-2)). Soil water stress delayed visible injury appearance and development by limiting ozone uptake. Data from charcoal-filtered treatments suggest the existence of an hourly flux threshold, below which may occur a complete ozone detoxification.

Transformation of dilative and contractive landslide debris into debris flows-An example from marin County, California

USGS Publications Warehouse

Fleming, R.W.; Ellen, S.D.; Algus, M.A.

1989-01-01

The severe rainstorm of January 3, 4 and 5, 1982, in the San Francisco Bay area, California, produced numerous landslides, many of which transformed into damaging debris flows. The process of transformation was studied in detail at one site where only part of a landslide mobilized into several episodes of debris flow. The focus of our investigation was to learn whether the landslide debris dilated or contracted during the transformation from slide to flow. The landslide debris consisted of sandy colluvium that was separable into three soil horizons that occupied the axis of a small topographic swale. Failure involved the entire thickness of colluvium; however, over parts of the landslide, the soil A-horizon failed separately from the remainder of the colluvium. Undisturbed samples were taken for density measurements from outside the landslide, from the failure zone and overlying material from the part of the landslide that did not mobilize into debris flows, and from the debris-flow deposits. The soil A-horizon was contractive and mobilized to flows in a process analogous to liquefaction of loose, granular soils during earthquakes. The soil B- and C-horizons were dilative and underwent 2 to 5% volumetric expansion during landslide movement that permitted mobilization of debris-flow episodes. Several criteria can be used in the field to differentiate between contractive and dilative behavior including lag time between landsliding and mobilization of flow, episodic mobilization of flows, and partial or complete transformation of the landslide. ?? 1989.

Variation in aluminum, iron, and particle concentrations in oxic groundwater samples collected by use of tangential-flow ultrafiltration with low-flow sampling

NASA Astrophysics Data System (ADS)

Szabo, Zoltan; Oden, Jeannette H.; Gibs, Jacob; Rice, Donald E.; Ding, Yuan

2002-02-01

Particulates that move with ground water and those that are artificially mobilized during well purging could be incorporated into water samples during collection and could cause trace-element concentrations to vary in unfiltered samples, and possibly in filtered samples (typically 0.45-um (micron) pore size) as well, depending on the particle-size fractions present. Therefore, measured concentrations may not be representative of those in the aquifer. Ground water may contain particles of various sizes and shapes that are broadly classified as colloids, which do not settle from water, and particulates, which do. In order to investigate variations in trace-element concentrations in ground-water samples as a function of particle concentrations and particle-size fractions, the U.S. Geological Survey, in cooperation with the U.S. Air Force, collected samples from five wells completed in the unconfined, oxic Kirkwood-Cohansey aquifer system of the New Jersey Coastal Plain. Samples were collected by purging with a portable pump at low flow (0.2-0.5 liters per minute and minimal drawdown, ideally less than 0.5 foot). Unfiltered samples were collected in the following sequence: (1) within the first few minutes of pumping, (2) after initial turbidity declined and about one to two casing volumes of water had been purged, and (3) after turbidity values had stabilized at less than 1 to 5 Nephelometric Turbidity Units. Filtered samples were split concurrently through (1) a 0.45-um pore size capsule filter, (2) a 0.45-um pore size capsule filter and a 0.0029-um pore size tangential-flow filter in sequence, and (3), in selected cases, a 0.45-um and a 0.05-um pore size capsule filter in sequence. Filtered samples were collected concurrently with the unfiltered sample that was collected when turbidity values stabilized. Quality-assurance samples consisted of sequential duplicates (about 25 percent) and equipment blanks. Concentrations of particles were determined by light scattering.

Baleen Hydrodynamics and Morphology of Cross-Flow Filtration in Balaenid Whale Suspension Feeding

PubMed Central

Werth, Alexander J.; Potvin, Jean

2016-01-01

The traditional view of mysticete feeding involves static baleen directly sieving particles from seawater using a simple, dead-end flow-through filtration mechanism. Flow tank experiments on bowhead (Balaena mysticetus) baleen indicate the long-standing model of dead-end filtration, at least in balaenid (bowhead and right) whales, is not merely simplistic but wrong. To recreate continuous intraoral flow, sections of baleen were tested in a flume through which water and buoyant particles circulated with variable flow velocity. Kinematic sequences were analyzed to investigate movement and capture of particles by baleen plates and fringes. Results indicate that very few particles flow directly through the baleen rack; instead much water flows anteroposteriorly along the interior (lingual) side of the rack, allowing items to be carried posteriorly and accumulate at the posterior of the mouth where they might readily be swallowed. Since water flows mainly parallel to rather than directly through the filter, the cross-flow mechanism significantly reduces entrapment and tangling of minute items in baleen fringes, obviating the need to clean the filter. The absence of copepods or other prey found trapped in the baleen of necropsied right and bowhead whales supports this hypothesis. Reduced through-baleen flow was observed with and without boundaries modeling the tongue and lips, indicating that baleen itself is the main if not sole agent of crossflow. Preliminary investigation of baleen from balaenopterid whales that use intermittent filter feeding suggests that although the biomechanics and hydrodynamics of oral flow differ, cross-flow filtration may occur to some degree in all mysticetes. PMID:26918630

Prehistoric Agriculture and Soil Fertility on Lava Flows in Northern Arizona, USA: Results from the San Francisco Volcanic Field REU

NASA Astrophysics Data System (ADS)

Broadman, E.; Anderson, K. C.

2013-12-01

The San Francisco Volcanic Field in northern Arizona is home to ~600 cinder cones, the youngest of which is Sunset Crater (erupted ~AD 1100). This study documents trends in available phosphate and nitrate content with time, testing whether lowered soil pH from the addition of Sunset cinders increased soil fertility and became a factor in Anasazi agricultural success. Soil fertility is examined both before and after Sunset's eruption in soils of different ages that have developed from eolian deposition on top of lava flows. An increase in phosphate and nitrate levels following acidification would suggest that the presence of Sunset cinders brought the soils to the optimal pH for mobilization of these nutrients. The combined effects of the cinder layer retaining nutrients and water, wetter climates, and increases in phosphate and nitrate (both limiting nutrients for plant growth), would have contributed to Anasazi agricultural success after Sunset's eruption. Samples for this study were taken from eolian-derived soils of different ages atop lava flows in the San Francisco Volcanic Field. OSL data from these soils on Strawberry and SP Craters' lava flows yielded age estimates of ~12.3 ka (Strawberry) and ~32.7 ka (SP), on which a soil chronosequence was based. Results from the chronosequence supported these OSL ages, indicating that soils on the SP flow are older than those on the Strawberry flow. Field descriptions, Harden Development Indices, particle size analysis, and nutrient content analysis were used for this aspect of the project. An experimental acid wash method will be used to simulate the addition of Sunset's acidic cinders, and will yield data for phosphate and nitrate content after Sunset erupted. Preliminary results indicate that phosphate and nitrate accumulate in upper, eolian-derived horizons (Av, Bw) and in more deeply buried carbonate horizons (Bk). Higher concentrations of phosphate and nitrate were found in older (SP) soils than younger (Strawberry) soils, suggesting that these nutrients increase over time with eolian deposition and soil development. Results from this study will yield information on the impact of volcanic eruptions and soil development on prehistoric agriculture and soil fertility. This study contributes to our understanding of the interactions between eruptions and human populations.

Comparative study on nutrient removal of agricultural non-point source pollution for three filter media filling schemes in eco-soil reactors.

PubMed

Du, Fuyi; Xie, Qingjie; Fang, Longxiang; Su, Hang

2016-08-01

Nutrients (nitrogen and phosphorus) from agricultural non-point source (NPS) pollution have been increasingly recognized as a major contributor to the deterioration of water quality in recent years. The purpose of this article is to investigate the discrepancies in interception of nutrients in agricultural NPS pollution for eco-soil reactors using different filling schemes. Parallel eco-soil reactors of laboratory scale were created and filled with filter media, such as grit, zeolite, limestone, and gravel. Three filling schemes were adopted: increasing-sized filling (I-filling), decreasing-sized filling (D-filling), and blend-sized filling (B-filling). The systems were intermittent operations via simulated rainstorm runoff. The nutrient removal efficiency, biomass accumulation and vertical dissolved oxygen (DO) distribution were defined to assess the performance of eco-soil. The results showed that B-filling reactor presented an ideal DO for partial nitrification-denitrification across the eco-soil, and B-filling was the most stable in the change of bio-film accumulation trends with depth in the three fillings. Simultaneous and highest removals of NH4(+)-N (57.74-70.52%), total nitrogen (43.69-54.50%), and total phosphorus (42.50-55.00%) were obtained in the B-filling, demonstrating the efficiency of the blend filling schemes of eco-soil for oxygen transfer and biomass accumulation to cope with agricultural NPS pollution.

Mixed forest plantations can efficiently filter rainfall deposits of sulfur and chlorine in Western China

PubMed Central

Zhao, Hairong; Yang, Wanqin; Wu, Fuzhong; Tan, Bo

2017-01-01

Forest filtering is a well-known and efficient method for diminishing atmospheric pollutant (such as SO42− and Cl−) inputs to soil and water; however, the filtering efficiencies of forests vary depending on the regional vegetation and climate. The rainy area of West China has suffered from heavy rainfall and human activity, which has potentially resulted in large amounts of sulfur and chlorine deposition, but little information is available regarding the filtering effects of typical plantations. Therefore, the migration of SO42− and Cl− from rainfall to throughfall, stemflow and runoff were investigated in a camphor (Cinnamomum camphora) plantation, a cryptomeria (Cryptomeria fortunei) plantation and a mixed plantation in a 9-month forest hydrology experiment. The results indicated the following: (i) The total SO42− and Cl− deposition was 43.05 kg ha−1 and 5.25 kg ha−1, respectively. (ii) The cover layer had the highest interception rate (60.08%), followed by the soil layer (16.02%) and canopy layer (12.85%). (iii) The mixed plantation resulted in the highest SO42− (37.23%) and Cl− (51.91%) interception rates at the forest ecosystem scale, and the interception rate increased with increasing rainfall. These results indicate that mixed plantations can effectively filter SO42− and Cl− in this area and in similar areas. PMID:28134356

A tracer experiment to study flow paths of water in a forest soil

NASA Astrophysics Data System (ADS)

Feyen, H.; Wunderli, H.; Wydler, H.; Papritz, A.

1999-12-01

This contribution discusses a tracer experiment, which was performed to study the flow paths of water in a macroporous forest soil. The experiment was performed in the framework of a study on the cycling of nitrogen in forested Prealpine catchments, in which losses of nitrate from virtually pristine areas were observed. Two soil plots with distinct micro-topography and top-soil were investigated: a well drained mor humus on a mound and a wet muck humus in a small depression. To reveal the effect of the soil horizons on the flow regime, tracers were applied both onto the soil surface and injected into the sub-soil. Tracers injected directly into the gleyic sub-soil reached the outlet (at a distance of 3.3 m) about 1000 times faster than could be expected from the saturated hydraulic conductivity of the soil matrix. Peak concentrations were observed after 18 (muck humus, tracer recovery 31%) to 70 min (mor humus, tracer recovery 40%). The peak concentration was 10 times smaller on the drier mor humus plot as compared to the muck humus. The mobile water content of the sub-soil varied between 0.5 (muck humus) and 1.3% (mor humus) of the total available soil water. The discrepancy in residence time, peak concentration and volume of mobile water between both sub-soils can be attributed to the differently structured sub-soil (longer travel distance and mixing volume in the drier mor humus). Tracers applied onto the soil surface resulted in a much slower breakthrough (tracer peaks after 400-700 min). Thus, in contrast to the sub-soil, flow through the matrix was the predominating transport process in the upper humus layers of both plots.

Estimating soil hydraulic properties from soil moisture time series by inversion of a dual-permeability model

NASA Astrophysics Data System (ADS)

Dalla Valle, Nicolas; Wutzler, Thomas; Meyer, Stefanie; Potthast, Karin; Michalzik, Beate

2017-04-01

Dual-permeability type models are widely used to simulate water fluxes and solute transport in structured soils. These models contain two spatially overlapping flow domains with different parameterizations or even entirely different conceptual descriptions of flow processes. They are usually able to capture preferential flow phenomena, but a large set of parameters is needed, which are very laborious to obtain or cannot be measured at all. Therefore, model inversions are often used to derive the necessary parameters. Although these require sufficient input data themselves, they can use measurements of state variables instead, which are often easier to obtain and can be monitored by automated measurement systems. In this work we show a method to estimate soil hydraulic parameters from high frequency soil moisture time series data gathered at two different measurement depths by inversion of a simple one dimensional dual-permeability model. The model uses an advection equation based on the kinematic wave theory to describe the flow in the fracture domain and a Richards equation for the flow in the matrix domain. The soil moisture time series data were measured in mesocosms during sprinkling experiments. The inversion consists of three consecutive steps: First, the parameters of the water retention function were assessed using vertical soil moisture profiles in hydraulic equilibrium. This was done using two different exponential retention functions and the Campbell function. Second, the soil sorptivity and diffusivity functions were estimated from Boltzmann-transformed soil moisture data, which allowed the calculation of the hydraulic conductivity function. Third, the parameters governing flow in the fracture domain were determined using the whole soil moisture time series. The resulting retention functions were within the range of values predicted by pedotransfer functions apart from very dry conditions, where all retention functions predicted lower matrix potentials. The diffusivity function predicted values of a similar range as shown in other studies. Overall, the model was able to emulate soil moisture time series for low measurement depths, but deviated increasingly at larger depths. This indicates that some of the model parameters are not constant throughout the profile. However, overall seepage fluxes were still predicted correctly. In the near future we will apply the inversion method to lower frequency soil moisture data from different sites to evaluate the model's ability to predict preferential flow seepage fluxes at the field scale.

Hydrogeological characterization of soil/weathered zone and underlying fractured bedrocks in DNAPL contaminated areas using the electromagnetic flowmeter

NASA Astrophysics Data System (ADS)

Kang, E.; Yeo, I.

2011-12-01

Flowmeter tests were carried out to characterize hydrogeology at DNAPL contaminated site in Wonju, Korea. Aquifer and slug tests determined hydraulic conductivity of soil/weathered zone and underlying fractured bed rocks to be 2.95×10-6 to 7.11×10-6 m/sec and 9.14×10-7 to 2.59×10-6 m/sec, respectively. Ambient flowmeter tests under natural hydraulic conditions revealed that the inflow and outflow take place through the borehole of soil/weathered zone with a tendency of down flow in the borehole. In particular, the most permeable layer of 22 to 30 m below the surface was found to form a major groundwater flow channel. On the contrary, a slight inflow and outflow was observed in the borehole, and the groundwater that inflows in the bottom section of the fractured bedrock flows up and exits through to the most permeable layer. Hydraulic heads measured at nearby multi-level boreholes confirmed the down flow in the soil/weathered zone and the up flow in fractured bedrocks. It was also revealed that the groundwater flow converges to the most permeable layer. TCE concentration in groundwater was measured at different depths, and in the borehole of the soil/weathered zone, high TCE concentration was found with higher than 10 mg/L near to the water table and decreased to about 6 mg/L with depth. The fractured bedrocks have a relatively constant low TCE concentration through a 20 m thick screen at less than l mg/L. The hydrogeology of the up flow in the soil/weathered zone and the down flow in underlying fractured bedrock leads the groundwater flow, and subsequently TCE plume, mainly to the most permeable layer that also restricts the advective transport of TCE plume to underlying fractured bedrocks. The cross borehole flowmeter test was carried out to find any hydrogeological connection between the soil/weathered zone and underlying fractured bedrocks. When pumping groundwater from the soil/weathered zone, no induced flow by groundwater extraction was observed at the underlying fractured bedrocks, and the hydraulic connection was identified only within the soil/weathered zone. However, when pumping groundwater from the fractured bedrocks, the hydraulic response was observed in the soil/weathered zone rather than another fractured bedrock borehole. Thus, when pump-and-treat is adopted for remediating the dissolved plume of DNAPL, the pumping well should be placed in the soil/weathered zone. Otherwise, the pumping of groundwater from the underlying fractured bedrocks will disperse the TCE plume into underlying fractured bedrocks.

An experimental study of the fluid mechanics associated with porous walls

NASA Technical Reports Server (NTRS)

Ramachandran, N.; Heaman, J.; Smith, A.

1992-01-01

The fluid mechanics of air exiting from a porous material is investigated. The experiments are filter rating dependent, as porous walls with filter ratings differing by about three orders of magnitude are studied. The flow behavior is investigated for its spatial and temporal stability. The results from the investigation are related to jet behavior in at least one of the following categories: (1) jet coalescence effects with increasing flow rate; (2) jet field decay with increasing distance from the porous wall; (3) jet field temporal turbulence characteristics; and (4) single jet turbulence characteristics. The measurements show that coalescence effects cause jet development, and this development stage can be traced by measuring the pseudoturbulence (spatial velocity variations) at any flow rate. The pseudoturbulence variation with increasing mass flow reveals an initial increasing trend followed by a leveling trend, both of which are directly proportional to the filter rating. A critical velocity begins this leveling trend and represents the onset of fully developed jetting action in the flow field. A correlation is developed to predict the onset of fully developed jets in the flow emerging from a porous wall. The data further show that the fully developed jet dimensions are independent of the filter rating, thus providing a length scale for this type of flow field (1 mm). Individual jet characteristics provide another unifying trend with similar velocity decay behavior with distance; however, the respective turbulence magnitudes show vast differences between jets from the same sample. Measurements of the flow decay with distance from the porous wall show that the higher spatial frequency components of the jet field dissipate faster than the lower frequency components. Flow turbulence intensity measurements show an out of phase behavior with the velocity field and are generally found to increase as the distance from the wall is increased.

Bioclogging in Porous Media: Preferential Flow Paths and Anomalous Transport

NASA Astrophysics Data System (ADS)

Holzner, M.; Carrel, M.; Morales, V.; Derlon, N.; Beltran, M. A.; Morgenroth, E.; Kaufmann, R.

2016-12-01

Biofilms are sessile communities of microorganisms held together by an extracellular polymeric substance that enables surface colonization. In porous media (e.g. soils, trickling filters etc.) biofilm growth has been shown to affect the hydrodynamics in a complex fashion at the pore-scale by clogging individual pores and enhancing preferential flow pathways and anomalous transport. These phenomena are a direct consequence of microbial growth and metabolism, mass transfer processes and complex flow velocity fields possibly exhibiting pronounced three-dimensional features. Despite considerable past work, however, it is not fully understood how bioclogging interacts with flow and mass transport processes in porous media. In this work we use imaging techniques to determine the flow velocities and the distribution of biofilm in a porous medium. Three-dimensional millimodels are packed with a transparent porous medium and a glucose solution to match the optical refractive index. The models are inoculated with planktonic wildtype bacteria and biofilm cultivated for 60 h under a constant flow and nutrient conditions. The pore flow velocities in the increasingly bioclogged medium are measured using 3D particle tracking velocimetry (3D-PTV). The three-dimensional spatial distribution of the biofilm within the pore space is assessed by imaging the model with X-Ray microtomography. We find that biofilm growth increases the complexity of the pore space, leading to the formation of preferential flow pathways and "dead" pore zones. The probability of persistent high and low velocity regions (within preferential paths resp. stagnant flow regions) thus increases upon biofilm growth, leading to an enhancement of anomalous transport. The structural data seems to indicate that the largest pores are not getting clogged and carry the preferential flow, whereas intricated structures develop in the smallest pores, where the flow becomes almost stagnant. These findings may be relevant for applications such as bioremediation of contaminated aquifers, groundwater injection wells for geothermal or drinking water purposes, tertiary oil recovery.

Assimilating remote sensing observations of leaf area index and soil moisture for wheat yield estimates: An observing system simulation experiment

USDA-ARS?s Scientific Manuscript database

We develop a robust understanding of the effects of assimilating remote sensing observations of leaf area index and soil moisture (in the top 5 cm) on DSSAT-CSM CropSim-Ceres wheat yield estimates. Synthetic observing system simulation experiments compare the abilities of the Ensemble Kalman Filter...