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Sample records for 40h turbidity samples

  1. 40 CFR 141.22 - Turbidity sampling and analytical requirements.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 22 2010-07-01 2010-07-01 false Turbidity sampling and analytical... § 141.22 Turbidity sampling and analytical requirements. The requirements in this section apply to... the water distribution system at least once per day, for the purposes of making turbidity...

  2. Turbidity and color spectronephelometric measurements in consumable fluid samples

    NASA Astrophysics Data System (ADS)

    Oliveira, Luis; Clemente, M. P.

    2003-10-01

    Spectronephelometric measurement techniques are in the order of the day. We can apply these techniques to monitor the production of consumable fluids and to verify their quality. Products like Wine, Beer and Olive Oil for instance, are widely consumed over the world. These products do have a major role in people"s dietary habits and their quality is of greater concern from day to day. If we can make use of a monitoring system that is able to perform measurements in situ, on line and in real time, then we will obviously have the capacity to improve quality. Particles that are suspended in consumable fluid samples interact with radiation by scattering it in almost all directions. If we can detect this scattered radiation, then we have information on the suspended particles. Making use on some Physical relations, we can transpose this information to physical parameters like Color and Turbidity.

  3. Recovery of diverse microbes in high turbidity surface water samples using dead-end ultrafiltration

    PubMed Central

    Mull, Bonnie; Hill, Vincent R.

    2015-01-01

    Dead-end ultrafiltration (DEUF) has been reported to be a simple, field-deployable technique for recovering bacteria, viruses, and parasites from large-volume water samples for water quality testing and waterborne disease investigations. While DEUF has been reported for application to water samples having relatively low turbidity, little information is available regarding recovery efficiencies for this technique when applied to sampling turbid water samples such as those commonly found in lakes and rivers. This study evaluated the effectiveness of a DEUF technique for recoveringMS2 bacteriophage, enterococci, Escherichia coli, Clostridium perfringens, and Cryptosporidium parvum oocysts in surface water samples having elevated turbidity. Average recovery efficiencies for each study microbe across all turbidity ranges were: MS2 (66%), C. parvum (49%), enterococci (85%), E. coli (81%), and C. perfringens (63%). The recovery efficiencies for MS2 and C. perfringens exhibited an inversely proportional relationship with turbidity, however no significant differences in recovery were observed for C. parvum, enterococci, or E. coli. Although ultrafilter clogging was observed, the DEUF method was able to process 100-L surface water samples at each turbidity level within 60 min. This study supports the use of the DEUF method for recovering a wide array of microbes in large-volume surface water samples having medium to high turbidity. PMID:23064261

  4. Task Technical and Quality Assurance Plan for the Characterization of the Tank 40H Samples

    SciTech Connect

    Wilmarth, W.R.

    2000-07-12

    The High Level Waste Tank Farms store and process high-level liquid wastes from a number of sources including F- and H-Canyons and a recycle stream from the Defense Waste Processing Facility (DWPF). The deposition of sodium aluminosilicate along with sodium diuranate in the 242-16H evaporator system led to the removal of authorization to process High Level Waste containing DWPF recycle. Therefore, High Level Waste Engineering has requested SRTC to perform analysis of the contents of Tank 40H and associated transfers from sludge washing to ensure silicon levels are sufficiently low to allow processing of the supernate through the 3H Evaporator.

  5. Colorimetric estimation of inorganic phosphate in colored and/or turbid biological samples: assay of phosphohydrolases.

    PubMed

    Upreti, G C

    1984-03-01

    A simple method of inorganic phosphate determination for colored and/or turbid biological samples is described. The procedure is mild, and so is suitable for routine phosphohydrolase assays. Following deproteinization by ice-cold trichloroacetic (or silicotungstic) acid, the sample was treated with acid-washed charcoal to remove interference due to color. The phosphate in the colorless supernatant was assayed either by measuring the phosphomolybdate spectrophotometrically at 310 nm, following its extraction in organic solvents or by a modified Fiske and Subbarow method. The turbidity interference in the latter case was eliminated either by centrifugation, by sodium dodecyl sulfate treatment, or by extraction of reduced phosphomolybdate blue color by cyclohexanone. Though deproteinization by silicotungstic acid eliminated the turbidity problem, its use in conjunction with charcoal treatment was not convenient.

  6. Off-confocal Raman spectroscopy (OCRS) for subsurface measurements in layered turbid samples

    NASA Astrophysics Data System (ADS)

    Khan, Khan Mohammad; Ghosh, Nirmalya; Majumder, Shovan Kumar

    2016-09-01

    We report, for the first time, the development of a depth-sensitive Raman spectroscopy system for investigating subsurface depths in a layered turbid sample using the concept of varying Raman collection zones, while keeping the point of illumination fixed on the surface of the target sample. The system makes use of a conventional confocal Raman configuration and realizes the variation in Raman collection zones employing off-confocal detection. This is effected by moving the tip of the Raman detection fiber (acting as the pinhole aperture) from the focus of the Raman collection objective either by taking the point of detection away from the objective (along its axis) or bringing it closer to the objective (along the same axis), thereby essentially offering two ways of enabling subsurface interrogation at a given time. Another important attraction of the approach is that it can be used for analyzing layered turbid samples at depths beyond the reach of the conventional confocal Raman, though not at the cost of any further modifications in its instrumentation. Furthermore, the illumination point remains fixed on the sample surface and no adjustment is required in the sample arm, which indeed are significant advantages for depth-sensitive measurements in situ from layered turbid samples, particularly those having irregular surfaces (like biological tissues). The ability of the system to recover Raman spectra of the subsurface layer was demonstrated using a layered non-biological phantom and a biological tissue sample.

  7. Ultra-deep imaging of turbid samples by enhanced photon harvesting

    NASA Astrophysics Data System (ADS)

    Crosignani, Viera; Dvornikov, Alexander; Gratton, Enrico

    2013-02-01

    We constructed an advanced detection system for two-photon fluorescence microscopy that allows us to image in biological tissue and tissue phantoms up to the depth of a few mm with micron resolution. The innovation lies in the detection system which is much more sensitive to low level fluorescence signals than the fluorescence detection configuration used in conventional two-photon fluorescence microscopes. A wide area photocathode photomultiplier tube (PMT) was used to detect fluorescence photons directly from a wide (1 inch diameter) area of the turbid sample, as opposed to the photon collection by the microscope objective which can only collect light from a relatively small area of the sample. The optical path between the sample and the photocathode is refractive index matched to curtail losses at the boundaries due to reflections. The system has been successfully employed in the imaging of tissue phantoms simulating brain optical properties and in biological tissues, such as murine small intestine, colon, tumors, and other samples. The system has in-depth fluorescence lifetime imaging (FLIM) capabilities and is also highly suitable for SHG signal detection, such as collagen fibers and muscles, due to the intrinsically forward-directed propagation of SHG photons.

  8. Toxicity testing of marine, terrestrial, solid, liquid, clear, and turbid samples

    SciTech Connect

    Sabate, R.W.; Stiffey, A.V.; Dewailly, E.L.

    1994-12-31

    A novel, patented toxicity testing procedure that compares the light generated by the naturally bioluminescent marine dinoflagellate alga, Pyrocystis lunula, in the presence of toxins, to light from a non-toxic control, is sensitive in parts per billion to all substances considered toxic to which it has been subjected: chemical warfare agents, metals, detergents, pesticides, herbicides, anticancer drugs, oil-well drilling fluids and produced waters, marine antifouling paints, and others. Preparation and testing time is less than eight hours. Variability is 10% or less. Solids and turbid or darkly colored samples can be tested without correction. Small sample substrates (10 to 50{mu}l) in the buffered 3ml test medium do not significantly affect pH or salinity, which permits testing of marine or terrestrial samples without special preparation. Also, the organism is insensitive to selected solvents for lipophyllic test substances. EC{sub 50} of sodium lauryl (dodecyl) sulphate is 3.7 ppm, and correlation with the Mysid LC{sub 50} EPA 30,000 ppm toxicity limit is 63% light inhibition.

  9. Dense sampled transmission matrix for high resolution angular spectrum imaging through turbid media via compressed sensing (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Jang, Hwanchol; Yoon, Changhyeong; Choi, Wonshik; Eom, Tae Joong; Lee, Heung-No

    2016-03-01

    We provide an approach to improve the quality of image reconstruction in wide-field imaging through turbid media (WITM). In WITM, a calibration stage which measures the transmission matrix (TM), the set of responses of turbid medium to a set of plane waves with different incident angles, is preceded to the image recovery. Then, the TM is used for estimation of object image in image recovery stage. In this work, we aim to estimate highly resolved angular spectrum and use it for high quality image reconstruction. To this end, we propose to perform a dense sampling for TM measurement in calibration stage with finer incident angle spacing. In conventional approaches, incident angle spacing is made to be large enough so that the columns in TM are out of memory effect of turbid media. Otherwise, the columns in TM are correlated and the inversion becomes difficult. We employ compressed sensing (CS) for a successful high resolution angular spectrum recovery with dense sampled TM. CS is a relatively new information acquisition and reconstruction framework and has shown to provide superb performance in ill-conditioned inverse problems. We observe that the image quality metrics such as contrast-to-noise ratio and mean squared error are improved and the perceptual image quality is improved with reduced speckle noise in the reconstructed image. This results shows that the WITM performance can be improved only by executing dense sampling in the calibration stage and with an efficient signal reconstruction framework without elaborating the overall optical imaging systems.

  10. Holographic quantitative imaging of sample hidden by turbid medium or occluding objects

    NASA Astrophysics Data System (ADS)

    Bianco, V.; Miccio, L.; Merola, F.; Memmolo, P.; Gennari, O.; Paturzo, Melania; Netti, P. A.; Ferraro, P.

    2015-03-01

    Digital Holography (DH) numerical procedures have been developed to allow imaging through turbid media. A fluid is considered turbid when dispersed particles provoke strong light scattering, thus destroying the image formation by any standard optical system. Here we show that sharp amplitude imaging and phase-contrast mapping of object hidden behind turbid medium and/or occluding objects are possible in harsh noise conditions and with a large field-of view by Multi-Look DH microscopy. In particular, it will be shown that both amplitude imaging and phase-contrast mapping of cells hidden behind a flow of Red Blood Cells can be obtained. This allows, in a noninvasive way, the quantitative evaluation of living processes in Lab on Chip platforms where conventional microscopy techniques fail. The combination of this technique with endoscopic imaging can pave the way for the holographic blood vessel inspection, e.g. to look for settled cholesterol plaques as well as blood clots for a rapid diagnostics of blood diseases.

  11. New Approach to Purging Monitoring Wells: Lower Flow Rates Reduce Required Purging Volumes and Sample Turbidity

    EPA Science Inventory

    It is generally accepted that monitoring wells must be purged to access formation water to obtain “representative” ground water quality samples. Historically anywhere from 3 to 5 well casing volumes have been removed prior to sample collection to evacuate the standing well water...

  12. Radiometry of water turbidity measurements

    NASA Technical Reports Server (NTRS)

    Mccluney, W. R.

    1974-01-01

    An examination of a number of measurements of turbidity reported in the literature reveals considerable variability in the definitions, units, and measurement techniques used. Many of these measurements differ radically in the optical quantity measured. The radiometric basis of each of the most common definitions of turbidity is examined. Several commercially available turbidimeters are described and their principles of operation are evaluated radiometrically. It is recommended that the term turbidity be restricted to measurements based upon the light scattered by the sample with that scattered by standard suspensions of known turbidity. It is also recommended that the measurement procedure be standardized by requiring the use of Formazin as the turbidity standardizing material and that the Formazin Turbidity Unit (FTU) be adopted as the standard unit of turbidity.

  13. Decoupling scattering and absorption of turbid samples using a simple empirical relation between coefficients of the Kubelka-Munk and radiative transfer theories.

    PubMed

    Gaonkar, Harshavardhan Ashok; Kumar, Dinesh; Ramasubramaniam, Rajagopal; Roy, Arindam

    2014-05-01

    Efforts are underway to better understand the absorption properties of micro- and nano-sized particles due to their potential in various photonic applications. However, most of these particles exhibit strong scattering in the spectral regions of interest in addition to absorption. Due to strong interference from scattering, the absorption of these turbid samples cannot be directly measured using conventional spectroscopy techniques. The optical properties of these particles are also different from that of the bulk due to quantum confinement and plasmon resonance effects and cannot be inferred from their bulk properties. By measuring the total transmittance and total reflectance (diffuse and collimated) of turbid samples and using an empirical relation between the coefficients of the Kubelka-Munk and radiative transfer theories, we have demonstrated a method to calculate the absorption and reduced scattering coefficients of turbid samples. This method is capable of extracting the absorption coefficient of turbid samples with an error of 2%. Using this method, we have decoupled the specific absorption and specific reduced scattering coefficients of commercially available micro-sized iron oxide particles. The current method can be used to measure the optical properties of irregularly shaped particle dispersions, which are otherwise difficult to estimate theoretically.

  14. Extending the turbidity record: making additional use of continuous data from turbidity, acoustic-Doppler, and laser diffraction instruments and suspended-sediment samples in the Colorado River in Grand Canyon

    USGS Publications Warehouse

    Voichick, Nicholas; Topping, David J.

    2014-01-01

    Turbidity is a measure of the scattering and absorption of light in water, which in rivers is primarily caused by particles, usually sediment, suspended in the water. Turbidity varies significantly with differences in the design of the instrument measuring turbidity, a point that is illustrated in this study by side-by-side comparisons of two different models of instruments. Turbidity also varies with changes in the physical parameters of the particles in the water, such as concentration, grain size, grain shape, and color. A turbidity instrument that is commonly used for continuous monitoring of rivers has a light source in the near-infrared range (860±30 nanometers) and a detector oriented 90 degrees from the incident light path. This type of optical turbidity instrument has a limited measurement range (depending on pathlength) that is unable to capture the high turbidity levels of rivers that carry high suspended-sediment loads. The Colorado River in Grand Canyon is one such river, in which approximately 60 percent of the range in suspended-sediment concentration during the study period had unmeasurable turbidity using this type of optical instrument. Although some optical turbidimeters using backscatter or other techniques can measure higher concentrations of suspended sediment than the models used in this study, the maximum turbidity measurable using these other turbidimeters may still be exceeded in conditions of especially high concentrations of suspended silt and clay. In Grand Canyon, the existing optical turbidity instruments remain in use in part to provide consistency over time as new techniques are investigated. As a result, during these periods of high suspended-sediment concentration, turbidity values that could not be measured with the optical turbidity instruments were instead estimated from concurrent acoustic attenuation data collected using side-looking acoustic-Doppler profiler (ADP) instruments. Extending the turbidity record to the full

  15. Relations between continuous real-time turbidity data and discrete suspended-sediment concentration samples in the Neosho and Cottonwood Rivers, east-central Kansas, 2009-2012

    USGS Publications Warehouse

    Foster, Guy M.

    2014-01-01

    The Neosho River and its primary tributary, the Cottonwood River, are the primary sources of inflow to the John Redmond Reservoir in east-central Kansas. Sedimentation rate in the John Redmond Reservoir was estimated as 743 acre-feet per year for 1964–2006. This estimated sedimentation rate is more than 80 percent larger than the projected design sedimentation rate of 404 acre-feet per year, and resulted in a loss of 40 percent of the conservation pool since its construction in 1964. To reduce sediment input into the reservoir, the Kansas Water Office implemented stream bank stabilization techniques along an 8.3 mile reach of the Neosho River during 2010 through 2011. The U.S. Geological Survey, in cooperation with the Kansas Water Office and funded in part through the Kansas State Water Plan Fund, operated continuous real-time water-quality monitors upstream and downstream from stream bank stabilization efforts before, during, and after construction. Continuously measured water-quality properties include streamflow, specific conductance, water temperature, and turbidity. Discrete sediment samples were collected from June 2009 through September 2012 and analyzed for suspended-sediment concentration (SSC), percentage of sediments less than 63 micrometers (sand-fine break), and loss of material on ignition (analogous to amount of organic matter). Regression models were developed to establish relations between discretely measured SSC samples, and turbidity or streamflow to estimate continuously SSC. Continuous water-quality monitors represented between 96 and 99 percent of the cross-sectional variability for turbidity, and had slopes between 0.91 and 0.98. Because consistent bias was not observed, values from continuous water-quality monitors were considered representative of stream conditions. On average, turbidity-based SSC models explained 96 percent of the variance in SSC. Streamflow-based regressions explained 53 to 60 percent of the variance. Mean squared

  16. A linear gradient line source facilitates the use of diffusion models with high order approximation for efficient, accurate turbid sample optical properties recovery.

    PubMed

    Lee, Ming-Wei; Hung, Cheng-Hung; Liao, Jung-Li; Cheng, Nan-Yu; Hou, Ming-Feng; Tseng, Sheng-Hao

    2014-10-01

    In this paper, we demonstrate that a scanning MEMS mirror can be employed to create a linear gradient line source that is equivalent to a planar source. This light source setup facilitates the use of diffusion models of increased orders of approximation having closed form solution, and thus enhance the efficiency and accuracy in sample optical properties recovery. In addition, compared with a regular planar light source, the linear gradient line source occupies much less source area and has an elevated measurement efficiency. We employed a δ-P1 diffusion equation with a closed form solution and carried out a phantom study to understand the performance of this new method in determining the absorption and scattering properties of turbid samples. Moreover, our Monte Carlo simulation results indicated that this geometry had probing depths comparable to those of the conventional diffuse reflectance measurement geometry with a source-detector separation of 3 mm. We expect that this new source setup would facilitate the investigating of superficial volumes of turbid samples in the wavelength regions where tissue absorption coefficients are comparable to scattering coefficients.

  17. The Swift Turbidity Marker

    ERIC Educational Resources Information Center

    Omar, Ahmad Fairuz; MatJafri, Mohd Zubir

    2011-01-01

    The Swift Turbidity Marker is an optical instrument developed to measure the level of water turbidity. The components and configuration selected for the system are based on common turbidity meter design concepts but use a simplified methodology to produce rapid turbidity measurements. This work is aimed at high school physics students and is the…

  18. Inverse SORS for detecting a low Raman-active turbid sample placed inside a highly Raman-active diffusely scattering matrix - A feasibility study.

    PubMed

    Khan, Khan Mohd; Dutta, Surjendu B; Krishna, Hemant; Majumder, Shovan K

    2016-09-01

    The broad range of applications of spatially-offset Raman spectroscopy (SORS) were found to involve samples having only marginal differences in Raman cross-sections between the surface and subsurface targets. We report the results of a feasibility study to evaluate the potential of the approach to identify the presence of a very low Raman-active turbid sample placed inside a highly Raman-active diffusely scattering matrix. Paraffin sandwiched tissue blocks prepared by embedding slices of chicken muscle tissue into solid paraffin blocks were employed as representative samples for the study. It was found that in contrast to the several millimetres of probing depth reported in the earlier applications, the Raman signatures of tissue were best recovered when it was located beneath the surface of the paraffin block at a depth of around a millimetre, beyond which the quality of recovery was increasingly poorer. However, the probing depth could be further increased by increasing the thickness of the embedded tissue sections. The results clearly suggest that though the probing depth achievable under the current condition is less than that found in previous applications, nevertheless it is sufficient for various other applications that would not require probing as deep as was required earlier.

  19. Atmospheric turbidity over Taiwan

    NASA Astrophysics Data System (ADS)

    Liu, C. M.; Feng, T. S.

    The atmospheric turbidity over Taiwan is inferred from the measurements of the direct solar irradiance during the period from July 1982 to June 1987. The turbidity over urban sites, which ranges from 0.30 to 0.48 (mean value 0.39), is significantly higher than values observed over suburban (0.21-0.23), rural (0.16-0.18), and high mountain (0.09) sites. The highest turbidity is observed at Taipei where a positive correlation is found between the turbidity and the daily dustfall data. Low wind speed is usually accompanied with high turbidity. When the surface wind intercepts with mountains, the localized circulation initiated by the blocking of airflow may cause efficient accumulation of aerosols and hence the observed high turbidity. The turbidity tends to be inversely proportional to the stability of the planetary boundary layer (PBL); hence there is an increase of turbidity at most stations from early morning to noontime. A positive correlation between turbidity and r.h. (<80%) and dew point temperature is noted; a negative correlation is found between turbidity and visibility. The annual cycle of turbidity is characterized by spring-fall maxima and winter-summer minima, which is different from the cycle of winter-minimum and summer-maximum observed in the temperate zone. The seasonal change of the synoptic weather pattern occurring around Taiwan is proposed to explain the observed annual cycle.

  20. Permanent Turbidity-Standards

    PubMed Central

    Roessler, William G.; Brewer, Carl R.

    1967-01-01

    Permanent turbidity reference standards suitable for measurement of microbial suspensions were prepared by suspending finely divided titanium dioxide in aryl sulfonamide-formaldehyde or methylstyrene resins. Turbidities of these standards, adjusted to a useful range for microbiological and immunological studies, were compared with other reference standards in use today. Tube holders for a Coleman Photonephelometer and a Nepho-Colorimeter were modified to eliminate the water well and to allow use of optically standardized 10-, 16-, or 18-mm test tubes. The standards and the tube holders have been used satisfactorily for more than 12 years. Images Fig. 5 Fig. 6 PMID:6077410

  1. Turbidity trends at tucson, Arizona.

    PubMed

    Heidel, K

    1972-09-08

    Variations in atmospheric turbidity at Tucson, Arizona, since 1956 are similar to those at Mauna Loa in Hawaii, especially before January 1970. The turbidity at both locations increased markedly in 1963 after the Bali eruption. Since January 1970, the turbidity has returned to its pre-1963 level at Mauna Loa, but has remained relatively high at Tucson.

  2. Turbidity and suspended sediment in the upper Esopus Creek watershed, Ulster County, New York

    USGS Publications Warehouse

    McHale, Michael R.; Siemion, Jason

    2014-01-01

    Discharge, SSC, and turbidity were strongly related at the Coldbrook site but not at every monitoring site. In general, relations between discharge and SSC and turbidity were strongest at sites with high SSCs, with the exception of Stony Clove Creek. Stony Clove Creek had high SSCs and turbidity regardless of discharge, and although concentrations and turbidity values generally increased with increasing discharge, the relation was not strong. Five of the six sites used to investigate the relations between SSC and laboratory turbidity had a coefficient of determination (r2) greater than 0.7. Relations were not as strong between SSC and the turbidity measured by in situ probes because the period of record was shorter and therefore the sample sizes were smaller. Data from in situ turbidity probes were strongly related to turbidity data measured in the laboratory for all but one of the monitoring sites where the relation was strongly leveraged by one sample. Although the in situ turbidity probes appeared to provide a good surrogate for SSC and could allow more accurate calculations of suspended-sediment load than discrete suspended-sediment samples alone, more data would be required to define the regression models throughout the range in discharge, SSCs, and turbidity levels that occur at each monitoring site. Nonetheless, the in situ probes provided much greater detail about the relation between discharge and turbidity than did the grab samples and storm samples measured in the laboratory.

  3. Marshes and turbid waters

    NASA Technical Reports Server (NTRS)

    Verger, F. (Principal Investigator)

    1972-01-01

    There are no author-identified significant results in this report. The study of the alluvial zones of the French Atlantic littoral at a taxonomic scale which can bring out the general nature of the sediments and their geomorphic forms is being achieved with the aid of ERTS-1 imagery. It will be necessary to run as many lines as possible to study both the alluvial plains, indicating the seasonal phases of the lowest and highest humidity, as well as the turbidity of littoral waters which change in relation to the tides. A better understanding of these alluvial zones and the origin of the sedimentary forms will not be limited to theoretical interest alone, but will have practical application in numerous fields such as agriculture, shell fishing, and land reclamation.

  4. Coherent label-free imaging through turbidity: a holographic approach

    NASA Astrophysics Data System (ADS)

    Bianco, V.; Paturzo, M.; Marchesano, V.; Miccio, L.; Memmolo, P.; Ferraro, P.

    2016-03-01

    A challenging issue has to be faced in microscopy whenever samples are immersed inside a dynamic turbid medium, as occluding objects provoke severe light scattering or unpredictable time-variable phase delays that scramble the object information. In these cases, the transmission matrix of the medium cannot be fully characterized. Here we show a simple technique, named Multi-Look Digital Holography (MLDH), able to fully recover the useful signal of biological specimens dipped inside a turbid liquid phase. Multiple hologram recordings are incoherently combined to synthesize the whole complex field diffused by the sample, which is revealed through turbidity providing quantitative phase-contrast information. Moreover, we show that the presence of a turbid medium can have a positive effect on a coherent imaging system, helping to reduce the effect of speckle artifacts. In other words, occluding biological elements, like e.g. Red Blood Cells (RBCs), can be thought as useful optical components providing denoising capabilities.

  5. Mathematical Modelling of Turbidity Currents

    NASA Astrophysics Data System (ADS)

    Fay, G. L.; Fowler, A.; Howell, P.

    2011-12-01

    A turbidity current is a submarine sediment flow which propagates downslope through the ocean into the deep sea. Turbidity currents can occur randomly and without much warning and consequently are hard to observe and measure. The driving force in a turbidity current is the presence of sediment in the current - gravity acts on the sediment in suspension, causing it to move downstream through the ocean water. A phenomenon known as ignition or autosuspension has been observed in turbidity currents in submarine canyons, and it occurs when a current travelling downslope gathers speed as it erodes sediment from the sea floor in a self-reinforcing cycle. Using the turbidity current model of Parker et al. (Journal of Fluid Mechanics, 1986) we investigate the evolution of a 1-D turbidity current as it moves downstream. To seek a better understanding of the dynamics of flow as the current evolves in space and time, we present analytical results alongside computed numerical solutions, incorporating entrainment of water and erosion and deposition of sediment. We consider varying slope functions and inlet conditions and attempt to predict when the current will become extinct. We examine currents which are in both supercritical and subcritical flow regimes and consider the dynamics of the flow as the current switches regime.

  6. Turbidity - a Semi-Continuous Monitoring Option for Suspended Solids

    NASA Astrophysics Data System (ADS)

    Lendvay, J. M.; Rosasco, M. V.; David, K. E.

    2012-12-01

    Redwood Creek, a third order coastal stream flowing through Muir Woods National Monument and Golden Gate National Recreation Area in Marin County, California, was once the spawning grounds for a relatively large population of Coho Salmon (Oncorhynchus kisutch). In recent years less than 1% of historic populations have been returning to the stream. Redwood creek is currently undergoing extensive ecological restoration in an attempt to improve the spawning habitat for the salmon. The original stream path has been altered in the past to make way for development and the National Park Service has been working towards restoring much of the stream's natural functionality with the hope that the salmon population will increase. The restoration process has altered the surrounding riparian landscape in the Redwood Creek watershed. Riparian disturbance caused by vegetation and levee removal as a part of the restoration process followed by installation of seedlings raises concern about the concentration of sediments in the water. Throughout 2011-2012 three parameters for water quality were monitored at Redwood Creek. Suspended sediment concentration (SSC) and total suspended solids (TSS) measurements to determine the concentration of suspended particles in the water column at a given point in time. Turbidity, measured in Nephelometric Turbidity Units (NTU) is a measure of the water's cloudiness caused by suspended particles. Turbidity measurements are favored as they provide a semi-automated monitoring option. Therefore, development of a relationship between turbidity and SSC and TSS is desired. Water samples were analyzed for TSS and SSC using the EPA standard methods, and Turbidity was measured using a Hach 2100Q portable turbidimeter. Additional semi-continuous monitoring of turbidity was completed in situ using Hydrolab DS5X datasondes (with self-cleaning turbidity sensor). The relationship between TSS, SSC and turbidity was determined using a linear regression model for

  7. The impacts of turbidity for COD measurements using UV-Vis spectrometry and compensation method (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Wen, Yizhang; Hu, Yingtian; Wang, Xiaoping

    2016-09-01

    Ultraviolet absorption spectroscopy is one of physical methods used for chemical oxygen demand (COD) measurements of water. The absorbances in ultraviolet band have a relationship to COD. However, turbidity in water could scatter emitting light and influence the absorbances. So it is very important to compensate for the impact of turbidity. In this study, the absorption spectra of standard COD solution (potassium acid phthalate), turbidity solution (Formazine) and their mixture are sampled in the wavelength range from 220 to 750 nm. The impacts of turbidity for COD measurement and compensation method are studied based on these data. The absorbance of mixture substract the absorbance of turbidity solution is less than the absorbance of standard COD solution. The result indicates that turbidity particles decrease the light absorption of organic molecules. Furthermore, we discover that the impact of turbidity is greater for the larger absorbance of the standard COD solution. Then attenuation coeffcient (AC()) is introduced and calculated based on exprimental results. In the process of turbidity compensation, the turbidity of solution is estimated using the absorbance of visible wavelength. The absorption spectra of the turbidity in the ultraviolet wavelength are simulated using normalization technique. The satisfactory prediction result of COD is achieved for the mixture after the turbidity compensation. In conclusion, the new turbidity compensation method could eliminate the influence of turbidity for COD measurements based on absorption spectroscopy.

  8. Effect of turbidity on chlorination efficiency and bacterial persistence in drinking water.

    PubMed

    LeChevallier, M W; Evans, T M; Seidler, R J

    1981-07-01

    To define interrelationships between elevated turbidities and the efficiency of chlorination in drinking water, experiments were performed to measure bacterial survival, chlorine demand, and interference with microbiological determinations. Experiments were conducted on the surface water supplies for communities which practice chlorination as the only treatment. Therefore, the conclusions of this study apply only to such systems. Results indicated that disinfection efficiency (log10 of the decrease in coliform numbers) was negatively correlated with turbidity and was influenced by season, chlorine demand of the samples, and the initial coliform level. Total organic carbon was found to be associated with turbidity and was shown to interfere with maintenance of a free chlorine residual by creating a chlorine demand. Interference with coliform detection in turbid waters could be demonstrated by the recovery of typical coliforms from apparently negative filters. The incidence of coliform masking in the membrane filter technique was found to increase as the turbidity of the chlorinated samples increased. the magnitude of coliform masking in the membrane filter technique increased from less than 1 coliform per 100 ml in water samples of less than 5 nephelometric turbidity units to greater than 1 coliform per 100 ml in water samples of greater than 5 nephelometric turbidity units. Statistical models were developed to predict the impact of turbidity on drinking water quality. The results justify maximum contaminant levels for turbidity in water entering a distribution system as stated in the National Primary Drinking Water Regulations of the Safe Drinking Water Act.

  9. [Experimental research of turbidity influence on water quality monitoring of COD in UV-visible spectroscopy].

    PubMed

    Tang, Bin; Wei, Biao; Wu, De-Cao; Mi, De-Ling; Zhao, Jing-Xiao; Feng, Peng; Jiang, Shang-Hai; Mao, Ben-Jiang

    2014-11-01

    Eliminating turbidity is a direct effect spectroscopy detection of COD key technical problems. This stems from the UV-visible spectroscopy detected key quality parameters depend on an accurate and effective analysis of water quality parameters analytical model, and turbidity is an important parameter that affects the modeling. In this paper, we selected formazine turbidity solution and standard solution of potassium hydrogen phthalate to study the turbidity affect of UV--visible absorption spectroscopy detection of COD, at the characteristics wavelength of 245, 300, 360 and 560 nm wavelength point several characteristics with the turbidity change in absorbance method of least squares curve fitting, thus analyzes the variation of absorbance with turbidity. The results show, In the ultraviolet range of 240 to 380 nm, as the turbidity caused by particle produces compounds to the organics, it is relatively complicated to test the turbidity affections on the water Ultraviolet spectra; in the visible region of 380 to 780 nm, the turbidity of the spectrum weakens with wavelength increases. Based on this, this paper we study the multiplicative scatter correction method affected by the turbidity of the water sample spectra calibration test, this method can correct water samples spectral affected by turbidity. After treatment, by comparing the spectra before, the results showed that the turbidity caused by wavelength baseline shift points have been effectively corrected, and features in the ultraviolet region has not diminished. Then we make multiplicative scatter correction for the three selected UV liquid-visible absorption spectroscopy, experimental results shows that on the premise of saving the characteristic of the Ultraviolet-Visible absorption spectrum of water samples, which not only improve the quality of COD spectroscopy detection SNR, but also for providing an efficient data conditioning regimen for establishing an accurate of the chemical measurement methods.

  10. Hyperspectral Sensing for Turbid Water Quality Monitoring in Freshwater Rivers: Empirical Relationship between Reflectance and Turbidity and Total Solids

    PubMed Central

    Wu, Jiunn-Lin; Ho, Chung-Ru; Huang, Chia-Ching; Srivastav, Arun Lal; Tzeng, Jing-Hua; Lin, Yao-Tung

    2014-01-01

    Total suspended solid (TSS) is an important water quality parameter. This study was conducted to test the feasibility of the band combination of hyperspectral sensing for inland turbid water monitoring in Taiwan. The field spectral reflectance in the Wu river basin of Taiwan was measured with a spectroradiometer; the water samples were collected from the different sites of the Wu river basin and some water quality parameters were analyzed on the sites (in situ) as well as brought to the laboratory for further analysis. To obtain the data set for this study, 160 in situ sample observations were carried out during campaigns from August to December, 2005. The water quality results were correlated with the reflectivity to determine the spectral characteristics and their relationship with turbidity and TSS. Furthermore, multiple-regression (MR) and artificial neural network (ANN) were used to model the transformation function between TSS concentration and turbidity levels of stream water, and the radiance measured by the spectroradiometer. The value of the turbidity and TSS correlation coefficient was 0.766, which implies that turbidity is significantly related to TSS in the Wu river basin. The results indicated that TSS and turbidity are positively correlated in a significant way across the entire spectrum, when TSS concentration and turbidity levels were under 800 mg·L−1 and 600 NTU, respectively. Optimal wavelengths for the measurements of TSS and turbidity are found in the 700 and 900 nm range, respectively. Based on the results, better accuracy was obtained only when the ranges of turbidity and TSS concentration were less than 800 mg·L−1 and less than 600 NTU, respectively and used rather than using whole dataset (R2 = 0.93 versus 0.88 for turbidity and R2 = 0.83 versus 0.58 for TSS). On the other hand, the ANN approach can improve the TSS retrieval using MR. The accuracy of TSS estimation applying ANN (R2 = 0.66) was better than with the MR approach (R2 = 0

  11. Determination of Residual Chlorine and Turbidity in Drinking Water. Student Manual.

    ERIC Educational Resources Information Center

    Office of Water Program Operations (EPA), Cincinnati, OH. National Training and Operational Technology Center.

    This student's manual covers analytical methods for residual chlorine and turbidity. Topics include sample handling, permissable concentration levels, substitution of residual chlorine for bacteriological work, public notification, and the required analytical techniques to determine residual chlorine and turbidity. The publication is intended for…

  12. Determination of Residual Chlorine and Turbidity in Drinking Water. Instructor's Manual.

    ERIC Educational Resources Information Center

    Office of Water Program Operations (EPA), Cincinnati, OH. National Training and Operational Technology Center.

    This instructor's guide presents analytical methods for residual chlorine and turbidity. Topics include sample handling, permissable concentration levels, substitution of residual chlorine for bacteriological work, public notification, and the required analytical techniques to determine residual chlorine and turbidity. This publication is intended…

  13. Laser-speckle-visibility acoustic spectroscopy in soft turbid media

    NASA Astrophysics Data System (ADS)

    Wintzenrieth, Frédéric; Cohen-Addad, Sylvie; Le Merrer, Marie; Höhler, Reinhard

    2014-01-01

    We image the evolution in space and time of an acoustic wave propagating along the surface of turbid soft matter by shining coherent light on the sample. The wave locally modulates the speckle interference pattern of the backscattered light, which is recorded using a camera. We show both experimentally and theoretically how the temporal and spatial correlations in this pattern can be analyzed to obtain the acoustic wavelength and attenuation length. The technique is validated using shear waves propagating in aqueous foam. It may be applied to other kinds of acoustic waves in different forms of turbid soft matter such as biological tissues, pastes, or concentrated emulsions.

  14. Simple systems for treating pumped, turbid water with flocculants and a geotextile dewatering bag.

    PubMed

    Kang, Jihoon; McLaughlin, Richard A

    2016-11-01

    Pumping sediment-laden water from excavations is often necessary on construction sites. This water is often treated by pumping it through geotextile dewatering bags. The bags are not designed to filter the fine sediments that create high turbidity, but dosing with a flocculant prior to the bag could result in greater turbidity control. This study compared two systems for introducing flocculant: passive dosing of commercial solid biopolymer (chitosan) and injection of dissolved polyacrylamide (PAM) in a length of corrugated pipe connected to the bag. The biopolymer system consisted of sequential porous socks containing a "charging agent" followed by chitosan in the corrugated pipe with two levels of dosing. The dissolved PAM was injected into turbid water at a flow-weighted concentration at 1 mg L(-1). For each treatment, sediment-laden turbid water in the range of 2000 to 3500 nephelometric turbidity units (NTU) was pumped into the upstream of corrugated pipe and samples were taken from pipe entrance, pipe exit, and dewatering bag exit. Without flocculant treatment, the dewatering bag reduced turbidity by 70% but the addition of flocculant increased the turbidity reduction up to 97% relative to influent. At the pipe exit, the low-dose biopolymer was less effective in reducing turbidity (37%) but it was equally effective as the high-dose biopolymer or PAM injection after the bag. Our results suggest that a relatively simple treatment with flocculants, either passively or actively, can be very effective in reducing turbidity for pumped water on construction sites.

  15. Change in field turbidity and trace element concentrations during well purging

    USGS Publications Warehouse

    Gibs, J.; Szabo, Z.; Ivahnenko, T.; Wilde, F.D.

    2000-01-01

    Various physical and chemical properties were monitored sequentially in the field during well purging as indicators of stabilization of the composition of the water in the well. Turbidity was monitored on site during purging of oxic water from three wells with screened intervals open to an unconfined aquifer system in the Coastal Plain of southern New Jersey to determine if stabilization of turbidity is a reliable indicator of the optimum purge time required to collect unbiased trace element samples. Concurrent split (one filtered, one unfiltered) samples collected during purging of the wells were analyzed for concentrations of trace elements so that the relationships between trace element concentrations and turbidity could be compared. Turbidity correlated with the whole water recoverable (WWR) concentration of trace element species, such as iron (Fe), aluminum (Al), and manganese (Mn) in the oxic ground water. Turbidity appeared to be independent of other field-measured characteristics of water such as conductivity, pH, temperature, and dissolved oxygen. The WWR concentrations of lead and copper, considered to be hydrophobic, correlated significantly with the sum of the WWR concentration of Fe, Al, and Mn. High values of field-measured turbidity were a key indicator of an overestimate of ambient hydrophobic trace element WWR concentrations. Stabilization of turbidity was a better indicator of stable, unfiltered trace element concentrations than were the other commonly measured field characteristics. At one well, turbidity was a better indicator of stable, filtered trace element concentrations than the other commonly measured field characteristics. As analytical methods for trace elements improve resulting in smaller MRLs (method reporting levels) and better precision, turbidity of ground water at values of less than 10 NTU (nepheiometric turbidity units) will become important in interpreting the significance of both unfiltered and filtered sample results.

  16. Spectral scattering properties of turbid waters

    NASA Technical Reports Server (NTRS)

    Whitlock, C. H.; Poole, L. R.; Houghton, W. M.

    1980-01-01

    River water samples have been examined for optical scattering properties at wavelengths between 400 and 800 nm. Scattering coefficients were calculated from measurements of beam attenuation and absorption coefficients and are observed to vary with wavelength. At a fixed wavelength, the scattering coefficient is influenced by both phytoplankton concentration (as indicated by chlorophyll a) and suspended solids concentration. Measurements of small angle volume-scattering function indicate that the phase function at an angle of 1.5 deg is not constant for turbid waters and varies with both wavelength and beam attenuation coefficient. These data differ from previously published results for relatively clear oceanic and coastal waters. Caution is required when attempting to estimate scattering coefficient values from single-angle measurements of volume-scattering function.

  17. IMPACT OF TURBIDITY ON TCE AND DEGRADATION PRODUCTS IN GROUND WATER

    EPA Science Inventory

    Elevated particulate concentrations in ground water samples can bias contaminant concentration data. This has been particularly problematic for metal analyses where artificially increased turbidity levels can affect metals concentrations and confound interpretation of the data. H...

  18. Water turbidity estimation from airborne hyperspectral imagery and full waveform bathymetric LiDAR

    NASA Astrophysics Data System (ADS)

    Pan, Z.; Glennie, C. L.; Fernandez-Diaz, J. C.

    2015-12-01

    The spatial and temporal variations in water turbidity are of great interest for the study of fluvial and coastal environments; and for predicting the performance of remote sensing systems that are used to map these. Conventional water turbidity estimates from remote sensing observations have normally been derived using near infrared reflectance. We have investigated the potential of determining water turbidity from additional remote sensing sources, namely airborne hyperspectral imagery and single wavelength bathymetric LiDAR (Light Detection and Ranging). The confluence area of the Blue and Colorado River, CO was utilized as a study area to investigate the capabilities of both airborne bathymetric LiDAR and hyperspectral imagery for water turbidity estimation. Discrete and full waveform bathymetric data were collected using Optech's Gemini (1064 nm) and Aquarius (532 nm) LiDAR sensors. Hyperspectral imagery (1.2 m pixel resolution and 72 spectral bands) was acquired using an ITRES CASI-1500 imaging system. As an independent reference, measurements of turbidity were collected concurrent with the airborne remote sensing acquisitions, using a WET Labs EcoTriplet deployed from a kayak and turbidity was then derived from the measured backscatter. The bathymetric full waveform dataset contains a discretized sample of the full backscatter of water column and benthic layer. Therefore, the full waveform records encapsulate the water column characteristics of turbidity. A nonparametric support vector regression method is utilized to estimate water turbidity from both hyperspectral imagery and voxelized full waveform LiDAR returns, both individually and as a fused dataset. Results of all the evaluations will be presented, showing an initial turbidity prediction accuracy of approximately 1.0 NTU. We will also discuss our future strategy for enhanced fusion of the full waveform LiDAR and hyperspectral imagery for improved turbidity estimation.

  19. Quantitative fluorescence spectroscopy in turbid media: a practical solution to the problem of scattering and absorption.

    PubMed

    Chen, Yao; Chen, Zeng-Ping; Yang, Jing; Jin, Jing-Wen; Zhang, Juan; Yu, Ru-Qin

    2013-02-19

    The presence of practically unavoidable scatterers and background absorbers in turbid media such as biological tissue or cell suspensions can significantly distort the shape and intensity of fluorescence spectra of fluorophores and, hence, greatly hinder the in situ quantitative determination of fluorophores in turbid media. In this contribution, a quantitative fluorescence model (QFM) was proposed to explicitly model the effects of the scattering and absorption on fluorescence measurements. On the basis of the proposed model, a calibration strategy was developed to remove the detrimental effects of scattering and absorption and, hence, realize accurate quantitative analysis of fluorophores in turbid media. A proof-of-concept model system, the determination of free Ca(2+) in turbid media using Fura-2, was utilized to evaluate the performance of the proposed method. Experimental results showed that QFM can provide quite precise concentration predictions for free Ca(2+) in turbid media with an average relative error of about 7%, probably the best results ever achieved for turbid media without the use of advanced optical technologies. QFM has not only good performance but also simplicity of implementation. It does not require characterization of the light scattering properties of turbid media, provided that the light scattering and absorption properties of the test samples are reasonably close to those of the calibration samples. QFM can be developed and extended in many application areas such as ratiometric fluorescent sensors for quantitative live cell imaging.

  20. NIR remission spectroscopy of turbid media

    NASA Astrophysics Data System (ADS)

    Krauter, P.; Foschum, F.; Kienle, A.

    2013-06-01

    We present a method for the determination of absorption spectra in VIS and NIR spectra of turbid media without the need for calibration. Measurements of the absorption spectra of a phantom and butter are presented.

  1. Laser speckle visibility acoustic spectroscopy in soft turbid media

    NASA Astrophysics Data System (ADS)

    Wintzenrieth, Frédéric; Cohen-Addad, Sylvie; Le Merrer, Marie; Höhler, Reinhard

    2014-03-01

    We image the evolution in space and time of an acoustic wave propagating along the surface of turbid soft matter by shining coherent light on the sample. The wave locally modulates the speckle interference pattern of the backscattered light and the speckle visibility[2] is recorded using a camera. We show both experimentally and theoretically how the temporal and spatial correlations in this pattern can be analyzed to obtain the acoustic wavelength and attenuation length. The technique is validated using shear waves propagating in aqueous foam.[3] It may be applied to other kinds of acoustic wave in different forms of turbid soft matter, such as biological tissues, pastes or concentrated emulsions. Now at Université Lyon 1 (ILM).

  2. Continuous Turbidity Monitoring in the Indian Creek Watershed, Tazewell County, Virginia, 2006-08

    USGS Publications Warehouse

    Moyer, Douglas; Hyer, Kenneth

    2009-01-01

    Thousands of miles of natural gas pipelines are installed annually in the United States. These pipelines commonly cross streams, rivers, and other water bodies during pipeline construction. A major concern associated with pipelines crossing water bodies is increased sediment loading and the subsequent impact to the ecology of the aquatic system. Several studies have investigated the techniques used to install pipelines across surface-water bodies and their effect on downstream suspended-sediment concentrations. These studies frequently employ the evaluation of suspended-sediment or turbidity data that were collected using discrete sample-collection methods. No studies, however, have evaluated the utility of continuous turbidity monitoring for identifying real-time sediment input and providing a robust dataset for the evaluation of long-term changes in suspended-sediment concentration as it relates to a pipeline crossing. In 2006, the U.S. Geological Survey, in cooperation with East Tennessee Natural Gas and the U.S. Fish and Wildlife Service, began a study to monitor the effects of construction of the Jewell Ridge Lateral natural gas pipeline on turbidity conditions below pipeline crossings of Indian Creek and an unnamed tributary to Indian Creek, in Tazewell County, Virginia. The potential for increased sediment loading to Indian Creek is of major concern for watershed managers because Indian Creek is listed as one of Virginia's Threatened and Endangered Species Waters and contains critical habitat for two freshwater mussel species, purple bean (Villosa perpurpurea) and rough rabbitsfoot (Quadrula cylindrical strigillata). Additionally, Indian Creek contains the last known reproducing population of the tan riffleshell (Epioblasma florentina walkeri). Therefore, the objectives of the U.S. Geological Survey monitoring effort were to (1) develop a continuous turbidity monitoring network that attempted to measure real-time changes in suspended sediment (using

  3. Estimation of suspended sediment concentration from turbidity measurements for agrarian watersheds of Navarre (Spain)

    NASA Astrophysics Data System (ADS)

    Madrona, Cecilia; Campo-Bescós, Miguel A.; Giménez, Rafael

    2016-04-01

    analysis and neural networks will be applied. To this end, there is a complete database of turbidity -taken every ten minutes- and sediment concentration -and in some cases, the granulometry of this sediment- registered along a single event above a certain magnitude. In addition, there are turbidity measurements of water-sediment samples from some of those events carried out in the laboratory. The latter are compared with the turbidity measurements registered by the turbidimeter in the hydrological stations. First results show that the turbidity-SSC relationship has an accuracy that varies throughout the year following a roughly seasonal pattern. Thus, the best fit will be achieved by defining a turbidity-SSC model according to the type of event. Furthermore the water-sediment sampler eventually collect bedload sediment while turbidemeters only register suspended sediments. This fact is somehow spoiling the turbidity-SSC relationship.

  4. Image transfer through the complex scattering turbid media

    NASA Astrophysics Data System (ADS)

    Meglinski, I. V.; Berrocal, E.; Linne, M. A.; Greenhalgh, D. A.

    2007-05-01

    Seeing through a turbid medium such as fog, mist or clouds is a fascinating idea that would find applications in a large range of fields from research to industry. The main difficulty of this challenging task is related to the complexity of multiple scattering of optical radiation propagated through an ensemble of scattering particles and/or droplets randomly distributed in a medium. To deal with this challenging problem we develop a new Monte Carlo based computational technique able to simulate image transfer through the complex inhomogeneous turbid media. The model is able to identify the contribution of the scattering orders in the detected images for a particular medium. With the presented approach the simulation of laser beam propagation and image transfer of an object hidden within a turbid scattering medium has been performed. The results of simulation demonstrate a good agreement with the experimental results. The validation of the technique has been done by using several modeling samples of water polystyrene spheres solutions.

  5. Turbidity Dynamics in an Urbanized Headwater Stream

    NASA Astrophysics Data System (ADS)

    Wynn, T. M.; Utley, B. C.; Davis, K.; Simpson, J. A.

    2008-12-01

    Excess suspended sediment in streams degrades aquatic ecosystems, reduces reservoir capacity, increases drinking water treatment costs, and serves as a carrier for pollutants such as phosphorus, bacterial, heavy metals, and pesticides. Due to the high temporal variability of suspended sediment transport, continuous instream turbidity measurements are used as a surrogate for suspended sediment concentration. This variability is particularly pronounced in small urban streams (drainage areas < 100 sq. km). To evaluate turbidity dynamics within the Stroubles Creek watershed (14 sq. km), two Eureka Manta multi-parameter sondes with McVan wiped turbidity sensors were installed at two cross sections upstream and downstream of a 450-m reach experiencing active bank retreat. Turbidity was recorded every 10 min. from March 2006 to May 2007. The continuous turbidity records were evaluated for hysteresis and indications of contributions of bank retreat to the stream sediment load. While the transport of suspended sediment from upstream sources through the study reach is observed, channel erosion appears to be a significant source of sediment to the stream.

  6. Fingerprinting Persistent Turbidity in Sheep Creek Reservoir, Owhyee, Nevada

    NASA Astrophysics Data System (ADS)

    Ransom, R. N.; Hooper, R. L.; Kerner, D.; Nicols, S.

    2007-12-01

    Sheep Creek Reservoir near Owyhee, NV is historically a quality rainbow trout fishery. Persistent high-turbidity has been an issue since a major storm event in 2005 resulted in surface water runoff into the Reservoir. The high turbidity is adversely impacting the quality of the fishery. Initial turbidity measurements in 2005 were upwards of 80NTU and these numbers have only decreased to 30NTU over the past two summers. Field parameters indicate the turbidity is associated with high total suspended solids (TSS) and not algae. Five water samples collected from around the reservoir during June, 2007 indicated uniform TSS values in the range of 5 to 12mg/L and oriented powder x-ray diffraction(XRD) and transmission electron microscopy(TEM) analyses of suspended sediment shows very uniform suspended particulate mineralogy including smectite, mixed layer illite/smectite (I/S), discrete illite, lesser amounts of kaolin, sub-micron quartz and feldspar. Diatoms represent a ubiquitous but minor component of the suspended solids. Six soil samples collected from possible source areas around the reservoir were analyzed using both XRD and TEM to see if a source area for the suspended solids could be unambiguously identified. Soils on the east side of the reservoir contain smectite and mixed layer I/S but very little of the other clays. The less than 2 micron size fraction from soils collected from a playa on the topographic bench immediately to the west of the reservoir show a mineralogic finger-print essentially identical to the current suspended sediment. The suspended sediment probably originates on the bench to the west of the reservoir and cascades into the reservoir over the topographic break during extreme storm events. The topographic relief, short travel distance and lack of a suitable vegetated buffer zone to the west are all consistent with a primary persistent suspended sediment source from the west. Identification of the sediment source allows for design of a cost

  7. Characterization of Tank 40H Supernate and Hydroxide Washing of Sludge

    SciTech Connect

    Wilmarth, W.R.

    2001-01-15

    During June 2000, the 3H Evaporator system is scheduled to receive wash water from washing the sludge and supernate currently in Tank 40H. The supernate from Tank 40H contains concentrated supernate from Tank 38H, the 2H Evaporator drop tank. This material may contain soluble silicon from the DWPF recycle stream. Therefore, SRTC examined the contents of Tank 40H and simulated the hydroxide wash of the sludge. The results of these tests are discussed in this report.

  8. An evaluation of suspended sediments and turbidity in Cow Creek, Oregon

    USGS Publications Warehouse

    Curtiss, D.A.

    1982-01-01

    During a 6-month period from December 1980 through May 1981, samples were collected from Cow Creek near Azalea, Oreg., and analyzed for suspended sediment, particle-size distribution, and turbidity. Of the estimated suspended-sediment discharge of 4,270 tons for the 1981 water year, 95 percent (4,050 tons) was transported during a major storm event, December 2-4, 1980. The 1981 water year suspended-sediment discharge of 4,270 tons is well below the average annual suspended-sediment discharge of 22,000 tons reported earlier by Curtiss (1974). A clay-sediment transport curve was used in conjunction with the flow-duration curve to estimate average annual clay discharge of 3,700 tons for Cow Creek near Azalea. Turbidity in Cow Creek near Azalea is estimated to be equal to or less than 15 NTU (nephelometric turbidity units) 90 percent of the time. A method for predicting turbidity values in a hypothetical impoundment is presented in this report. This method utilizes a suspended-sediment transport curve of the fine (<0.002 mm) material and measures residual-turbidity values. This method probably could be used to assess the impact of proposed reservoirs on stream turbidities in basins similar to that of Cow Creek basin.

  9. Turbidity observations in sediment flux studies: Examples from Russian rivers in cold environments

    NASA Astrophysics Data System (ADS)

    Tananaev, N. I.; Debolskiy, M. V.

    2014-08-01

    Turbidity is commonly used as a proxy to estimate suspended sediment content in streams, and for hydroecological purposes. The scope of this paper is to give an outlook to wider applications of nephelometric turbidimetry as a method. Uncalibrated turbidity records in conjunction with water chemistry data prove useful in detecting watershed reaction to single hydrological events during the spring flood in Arctic Russia. The turbidimetric survey technique was applied to study the spatial variability of sediment yield features on small rivers of the south-eastern part of Sakhalin Island. Suspended sediment concentration (SSC) vs. turbidity relation follows the geological features of the terrain and reflects the land-use intensity within the watersheds. For our Igarka key site, a logarithmic regression model was developed as an instrument of SSC calculation with turbidity data for each of the four studied watersheds. A regional regression model was developed for this site, and supplementary water optics data (filtered sample turbidity) was employed to increase the reliability of SSC calculations. Our results show that factors influencing turbidity, namely water colour and sediment grain size, have to be considered in multivariate models, to minimize errors and acquire an understanding of what kind of physical response is actually measured by nephelometry-based instruments.

  10. The design of rapid turbidity measurement system based on single photon detection techniques

    NASA Astrophysics Data System (ADS)

    Yang, Yixin; Wang, Huanqin; Cao, Yangyang; Gui, Huaqiao; Liu, Jianguo; Lu, Liang; Cao, Huibin; Yu, Tongzhu; You, Hui

    2015-10-01

    A new rapid turbidity measurement system has been developed to measure the turbidity of drinking water. To determinate the turbidity quantitatively, the total intensity of scattering light has been measured and quantified as number of photons by adopting the single photon detection techniques (SPDT) which has the advantage of high sensitivity. On the basis of SPDT, the measurement system has been built and series of experiments have been carried out. Combining then the 90° Mie scattering theory with the principle of SPDT, a turbidity measurement model has been proposed to explain the experimental results. The experimental results show that a turbidity, which is as low as 0.1 NTU (Nephelometric Turbidity Units), can be measured steadily within 100 ms. It also shows a good linearity and stability over the range of 0.1-400 NTU and the precision can be controlled within 5% full scale. In order to improve its precision and stability, some key parameters, including the sampling time and incident light intensity, have been discussed. It has been proved that, to guarantee an excellent system performance, a good compromise between the measurement speed and the low power consumption should be considered adequately depending on the practical applications.

  11. 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.

  12. Verification of reflectance models in turbid waters

    NASA Technical Reports Server (NTRS)

    Tanis, F. J.; Lyzenga, D. R.

    1981-01-01

    Inherent optical parameters of very turbid waters were used to evaluate existing water reflectance models. Measured upwelling radiance spectra and Monte Carlo simulations of the radiative transfer equations were compared with results from models based upon two flow, quasi-single scattering, augmented isotropic scattering, and power series approximation. Each model was evaluated for three separate components of upwelling radiance: (1) direct sunlight; (2) diffuse skylight; and (3) internally reflected light. Limitations of existing water reflectance models as applied to turbid waters and possible applications to the extraction of water constituent information are discussed.

  13. Appearance and water quality of turbidity plumes produced by dredging in Tampa Bay, Florida

    USGS Publications Warehouse

    Goodwin, Carl R.; Michaelis, D.M.

    1984-01-01

    Turbidity plumes in Tampa Bay, Florida, produced during ship-channel dredging operations from February 1977 to August 1978, were monitored in order to document plume appearance and water quality, evaluate plume influence on the characteristics of Tampa Bay water, and provide a data base for comparison with other areas that have similar sediment, dredge, placement, containment, and tide conditions. The plumes investigated originated from the operation of one hopper dredge and three cutterhead-pipeline dredges. Composition of bottom sediment was found to vary from 85 percent sand and shell fragments to 60 percent silt and clay. Placement methods for dredged sediment included beach nourishment, stationary submerged discharge, oscillating surface discharge, and construction of emergent dikes. Tidal currents ranged from slack water to flow velocities of 0.60 meter per second. Plumes were monitored simultaneously by (1) oblique and vertical 35-millimeter aerial photography and (2) water-quality sampling to determine water clarity and concentrations of nutrients, metals, pesticides, and industrial compounds. Forty-nine photographs depict plumes ranging in length from a few tens of meters to several kilometers and ranging in turbidity level from <10 to 200,000 nephelometric turbidity units. The most visible turbidity plumes were produced by surface discharge of material with high sand content into unconfined placement areas during times of strong tidal currents. The least visible turbidity plumes were produced by discharge of material with high silt and clay content into areas enclosed by floating turbidity barriers during times of weak tidal currents. Beach nourishment from hopper-dredge unloading operations also produced plumes of low visibility. Primary turbidity plumes were produced directly by dredging and placement operations; secondary plumes were produced indirectly by resuspension of previously deposited material. Secondary plumes were formed both by erosion, in

  14. Spatial and temporal variations in turbidity on two inshore turbid reefs on the Great Barrier Reef, Australia

    NASA Astrophysics Data System (ADS)

    Browne, N. K.; Smithers, S. G.; Perry, C. T.

    2013-03-01

    This study describes the natural turbidity regimes at two inshore turbid reefs on the central Great Barrier Reef where wind-driven waves are the main agent of sediment resuspension. Many corals on inshore turbid reefs have adapted to high and fluctuating turbidity, however, anthropogenic activities such as dredging are speculated to produce larger and more prolonged turbidity events that may exceed the environmental tolerance and adaptive capacity of corals on these reefs. Natural turbidity regimes must be described and understood to determine whether and when coral communities on inshore turbid reefs are at risk from anthropogenically elevated turbidity, but at present few baseline studies exist. Here, we present turbidity data from (a) Middle Reef, a semi-protected reef located between Magnetic Island and Townsville and (b) Paluma Shoals, a reef exposed to higher energy wind and waves located in Halifax Bay. Instruments were deployed on both reefs for 16 days to measure spatial and temporal variations in turbidity and its driving forces (waves, currents, tides). Locally driven wind waves were the key driver of turbidity, but the strength of the relationship was dependent on wave exposure. Turbidity regimes thus vary markedly over individual reefs and this is reflected in community assemblage distributions, with a high abundance of heterotrophic corals (e.g. Goniopora) in reef habitats subjected to large fluctuations in turbidity (>100 NTU). A turbidity model developed using local wind speed data explained up to 75 % and up to 46 % of the variance in turbidity at Paluma Shoals and Middle Reef, respectively. Although the model was based on a brief two-week observational period, it reliably predicted variations in 24-h averaged turbidity and identified periods when turbidity rose above ambient baseline levels, offering reef managers insights into turbidity responses to modified climate and coastal sediment delivery regimes.

  15. Sapphire fiber evanescent wave absorption in turbid media.

    PubMed

    Zhang, Jian; Xiong, Feibing; Djeu, Nicholas

    2009-08-01

    The influence of particulates on sapphire fiber evanescent wave absorption by water has been studied. Suspensions containing micro-sized graphite flakes and glassy carbon powder were used. Conventional free-space transmittance measurements of these samples showed strong absorption and scattering, which severely screened the absorption by water. However, the absorption on the water band determined from the evanescent wave interaction was unaffected by the presence of the graphite flakes. These results indicate that fiber-optic evanescent wave chemical sensors may be suitable for process control applications involving turbid reactor streams.

  16. Using turbidity for designing water networks.

    PubMed

    Castaño, J A; Higuita, J C

    2016-05-01

    Some methods to design water networks with minimum fresh water consumption are based on the selection of a key contaminant. In most of these "single contaminant methods", a maximum allowable concentration of contaminants must be established in water demands and water sources. Turbidity is not a contaminant concentration but is a property that represents the "sum" of other contaminants, with the advantage that it can be cheaper and easily measured than biological oxygen demand, chemical oxygen demand, suspended solids, dissolved solids, among others. The objective of this paper is to demonstrate that turbidity can be used directly in the design of water networks just like any other contaminant concentration. A mathematical demonstration is presented and in order to validate the mathematical results, the design of a water network for a guava fudge production process is performed. The material recovery pinch diagram and nearest neighbors algorithm were used for the design of the water network. Nevertheless, this water network could be designed using other single contaminant methodologies. The maximum error between the expected and the real turbidity values in the water network was 3.3%. These results corroborate the usefulness of turbidity in the design of water networks.

  17. Computer mapping of turbidity and circulation patterns in Saginaw Bay, Michigan from LANDSAT data

    NASA Technical Reports Server (NTRS)

    Rogers, R. H. (Principal Investigator); Reed, L. E.; Smith, V. E.

    1975-01-01

    The author has identified the following significant results. LANDSAT was used as a basis for producing geometrically-corrected, color-coded imagery of turbidity and circulation patterns in Saginaw Bay, Michigan (Lake Huron). This imagery shows nine discrete categories of turbidity, as indicated by nine Secchi depths between 0.3 and 3.3 meters. The categorized imagery provided an economical basis for extrapolating water quality parameters from point samples to unsample areas. LANDSAT furnished a synoptic view of water mass boundaries that no amount of ground sampling or monitoring could provide.

  18. Effects of Prevailing Winds on Turbidity of a Shallow Estuary

    PubMed Central

    Cho, Hyun Jung

    2007-01-01

    Estuarine waters are generally more turbid than lakes or marine waters due to greater algal mass and continual re-suspension of sediments. The varying effects of diurnal and seasonal prevailing winds on the turbidity condition of a wind-dominated estuary were investigated by spatial and statistical analyses of wind direction, water level, turbidity, chlorophyll a, and PAR (Photosynthetically Active Radiation) collected in Lake Pontchartrain, Louisiana, USA. The prolonged prevailing winds were responsible for the long-term, large-scale turbidity pattern of the estuary, whereas the short-term changes in wind direction had differential effects on turbidity and water level in varying locations. There were temporal and spatial changes in the relationship between vertical light attenuation coefficient (Kd) and turbidity, which indicate difference in phytoplankton and color also affect Kd. This study demonstrates that the effect of wind on turbidity and water level on different shores can be identified through system-specific analyses of turbidity patterns. PMID:17617683

  19. The effects of soil properties on the turbidity of catchment soils from the Yongdam dam basin in Korea.

    PubMed

    Hur, Jin; Jung, Myung Chae

    2009-06-01

    Environmental concerns have been raised that suspended solids in turbid water adversely affect human health, and that their removal increases in the cost of water treatment. The Yongdam dam reservoir, located in the southwestern region of Korea, is severely affected by inflowing turbid water after storms. In this study, soil samples were collected from 37 sites in the Yongdam upstream basin to investigate mineralogical and environmental factors associated with the turbidity potential of soils in water environments. Turbidity potential was estimated by measuring the turbidity of soil-suspension solutions after settling for 24 h. The mineralogy of the soils was dominated by four minerals-quartz, microcline, albite, and muscovite-with lesser amounts of hornblende, chlorite, kaolinite, illite, and mixed layer illite. The quartz content was the most variable of the soil mineralogy among the collected samples. Principal-components analysis (PCA) was used to examine relationships between turbidity potential and other soil properties. The variables considered in the PCA included turbidity potential, quartz content, albite content, mean size of soil particles, clay content, clay mineral content, zeta potential, conductivity, and pH of the soil-suspension solution. The first two components of the PCA explained 52% of the overall variation of the selected variables. The first component was possibly explained by physical properties such as the size of the soil particles; the second was correlated with chemical properties of the soils, for example dissolution and extent of weathering. Closer examination of the PCA results revealed that the quartz content of the soils was negatively correlated with their turbidity potential. A linear correlation (r = 0.63) was obtained between measured turbidity potential and that predicted using multiple regression analysis based on the content of clay-sized particles, clay minerals, and quartz, and the conductivity of the soil

  20. Signal Preservation in Pulsing Turbidity Current Deposits

    NASA Astrophysics Data System (ADS)

    Keevil, G. M.; Dorrell, R. M.; McCaffrey, W. D.

    2014-12-01

    Recent debate has focused on the potential preservation of the signal of seismic events in the sedimentary record via the initiation of large-scale turbidity current flows. The failure of a seismic zone lying across a series of submarine canyon systems may initiate multiple linked turbidity currents from each canyon head. Such events can be distinguished from locally triggered turbidity currents by their deposits. Canyon systems may be expected to become progressively interconnected with depth. Differing run out times of each interconnected channel is expected to result in pulsing flow behavior, a key feature of such turbidity currents. Thus, cyclical waxing to waning flow behavior preserved in the rock record may be a key indicator of a large-scale seismic trigger. Novel experimental research is presented that explores the dynamics of pulsed turbidity currents. The experimental study is used to quantitatively examine controls on the time and length scale of signal preservation in pulsing density driven flows. The experiments consisted of a multi gate lock box, with the gates remotely operated by pneumatic rams. Gate timers allow for accurate experimental repeatability and a careful investigation of the effect of time spacing between flows on pulsing flow dynamics. Parameters investigated include volumes of material released, effective flow density and viscosity (as a proxy of flow mud content). Full flow field visualization was made using an array of interlinked HD cameras. Dyeing separate components of the flow different colors enabled detailed analysis of flow dynamic behavior occurring between head and tail. The secondary pulsing flow was seen to rapidly overtake the first flow. Observations of flow velocity and density suggested that due to stratification the secondary flow was travelling along the density interface between the main body of the primary flow and its turbulent wake. As the pulsing flows created in the laboratory experiments rapidly merged, it

  1. Polarization discrimination of coherently propagating light in turbid media

    SciTech Connect

    Sankaran, V.; Schoenenberger, K.; Maitland, D.J.; Walsh, J.T. Jr.

    1999-07-01

    We describe the use of degree of polarization to discriminate unscattered and weakly scattered light from multiply scattered light in an optically turbid material. We use spatially resolved measurements of the degree of polarization to compare how well linearly and circularly polarized light survives in a sample. Experiments were performed on common tissue phantoms consisting of polystyrene and Intralipid microsphere suspensions and on adipose and arterial tissue. The results indicate that polarization is maintained even after unpolarized irradiance through each sample has been extinguished by several orders of magnitude. The results show that polarized light propagation in common tissue phantoms is distinctly different from polarized light propagation in the two tissues investigated. Further, these experiments illustrate when polarization is an effective discrimination criterion and when it is not. The potential of a polarization-based discrimination scheme to image through the biological and nonbiological samples investigated here is also discussed. {copyright} 1999 Optical Society of America

  2. Evaluation and application of regional turbidity-sediment regression models in Virginia

    USGS Publications Warehouse

    Hyer, Kenneth; Jastram, John D.; Moyer, Douglas; Webber, James S.; Chanat, Jeffrey G.

    2015-01-01

    Conventional thinking has long held that turbidity-sediment surrogate-regression equations are site specific and that regression equations developed at a single monitoring station should not be applied to another station; however, few studies have evaluated this issue in a rigorous manner. If robust regional turbidity-sediment models can be developed successfully, their applications could greatly expand the usage of these methods. Suspended sediment load estimation could occur as soon as flow and turbidity monitoring commence at a site, suspended sediment sampling frequencies for various projects potentially could be reduced, and special-project applications (sediment monitoring following dam removal, for example) could be significantly enhanced. The objective of this effort was to investigate the turbidity-suspended sediment concentration (SSC) relations at all available USGS monitoring sites within Virginia to determine whether meaningful turbidity-sediment regression models can be developed by combining the data from multiple monitoring stations into a single model, known as a “regional” model. Following the development of the regional model, additional objectives included a comparison of predicted SSCs between the regional model and commonly used site-specific models, as well as an evaluation of why specific monitoring stations did not fit the regional model.

  3. Sediment concentrations, flow conditions, and downstream evolution of two turbidity currents, Monterey Canyon, USA

    USGS Publications Warehouse

    Xu, Jingping; Octavio E. Sequeiros,; Noble, Marlene A.

    2014-01-01

    The capacity of turbidity currents to carry sand and coarser sediment from shallow to deep regions in the submarine environment has attracted the attention of researchers from different disciplines. Yet not only are field measurements of oceanic turbidity currents a rare achievement, but also the data that have been collected consist mostly of velocity records with very limited or no suspended sediment concentration or grain size distribution data. This work focuses on two turbidity currents measured in Monterey Canyon in 2002 with emphasis on suspended sediment from unique samples collected within the body of these currents. It is shown that concentration and grain size of the suspended material, primarily controlled by the source of the gravity flows and their interaction with bed material, play a significant role in shaping the characteristics of the turbidity currents as they travel down the canyon. Before the flows reach their normal or quasi-steady state, which is defined by bed slope, bed roughness, and suspended grain size, they might pass through a preliminary adjustment stage where they are subject to capacity-driven deposition, and release heavy material in excess. Flows composed of fine (silt/clay) sediments tend to be thicker than those with sands. The measured velocity and concentration data confirm that flow patterns differ between the front and body of turbidity currents and that, even after reaching normal state, the flow regime can be radically disrupted by abrupt changes in canyon morphology.

  4. Estuarine turbidity, flushing, salinity, and circulation

    NASA Technical Reports Server (NTRS)

    Pritchard, D. W.

    1972-01-01

    The effects of estuarine turbidity, flushing, salinity, and circulation on the ecology of the Chesapeake Bay are discussed. The sources of fresh water, the variations in salinity, and the circulation patterns created by temperature and salinity changes are analyzed. The application of remote sensors for long term observation of water temperatures is described. The sources of sediment and the biological effects resulting from increased sediments and siltation are identified.

  5. Absorption coefficient instrument for turbid natural waters.

    PubMed

    Friedman, E; Poole, L; Cherdak, A; Houghton, W

    1980-05-15

    An instrument has been developed that directly measures the multispectral absorption coefficient of turbid natural water. The design incorporates methods for compensation of variation in the internal light source intensity, correction of the spectrally dependent nature of the optical elements, and correction for variation in background light level. When used in conjunction with a spectrally matched total attenuation instrument, the spectrally dependent scattering coefficient can also be derived. Systematic errors associated with multiple scattering have been estimated using Monte Carlo techniques.

  6. IR diver vision for turbidity mitigation

    NASA Astrophysics Data System (ADS)

    Milam, Jerry A.

    2010-04-01

    Commercial, forensic, and military divers often encounter turbid conditions which reduce visibility to zero. Under such conditions, work must be performed completely blind. The darkness resulting from high levels of turbidity is complete, and can be dangerous as well as disorienting. Such darkness can even occur near the surface on a bright and sunny day. Artificial underwater lighting is of no use in such situations, as it only makes matters worse (similar to the use of high beam headlights in dense fog). Certain wavelengths of infrared (IR) light have the ability to penetrate this underwater "fog," and thus form the basis of the current development. Turbidity results from clay, silt, finely divided organic and inorganic matter, soluble colored organic compounds, plankton and microscopic organisms suspended in water. The IR Diver Vision system described herein consists of a standard commercial diving mask of any of several configurations whereby an IR light source, IR video camera, video display, and power source may be integrated within or attached to the mask. The IR light source wavelength is compatible with the spectral bandwidth of the video camera. The camera field-of-view (FOV) is matched to the video display in order to provide a unity magnification and hence prevent diver ocular fatigue. The IR video camera, video display, power source and controls are compatible with extended use in a submarine environment. Some such masks will incorporate tilt/heading sensors and video indicators. 3-D Imaging, Inc. has developed prototypes and has patents pending on such devices.

  7. Turbidity and suspended-sediment transport in the Russian River Basin, California

    USGS Publications Warehouse

    Ritter, John R.; Brown, William M.

    1971-01-01

    The Russian River in north coastal California has a persistent turbidness, which has reportedly caused a decline in the success of the sports fishermen. As a consequence, the number of sports fishermen angling in the river has declined, and industries dependent on their business have suffered. To determine the source of the turbidity and the rate of sediment transport in the basin, a network of sampling station was established in February 1964 along the river, on some of its tributaries, and near Lake Pillsbury in the upper Eel River basin.

  8. Turbidity. Operational Control Tests for Wastewater Treatment Facilities. Instructor's Manual [and] Student Workbook.

    ERIC Educational Resources Information Center

    Carnegie, John W.

    Designed for individuals who have completed National Pollutant Discharge Elimination System (NPDES) level 1 laboratory training skills, this module provides waste water treatment plant operators with the basic skills and information needed to: (1) standardize a nephelometric turbidimeter; (2) determine the turbidity of a sample; and (3) calculate…

  9. Quantitative polarized Raman spectroscopy in highly turbid bone tissue

    PubMed Central

    Raghavan, Mekhala; Sahar, Nadder D.; Wilson, Robert H.; Mycek, Mary-Ann; Pleshko, Nancy; Kohn, David H.; Morris, Michael D.

    2010-01-01

    Polarized Raman spectroscopy allows measurement of molecular orientation and composition and is widely used in the study of polymer systems. Here, we extend the technique to the extraction of quantitative orientation information from bone tissue, which is optically thick and highly turbid. We discuss multiple scattering effects in tissue and show that repeated measurements using a series of objectives of differing numerical apertures can be employed to assess the contributions of sample turbidity and depth of field on polarized Raman measurements. A high numerical aperture objective minimizes the systematic errors introduced by multiple scattering. We test and validate the use of polarized Raman spectroscopy using wild-type and genetically modified (oim∕oim model of osteogenesis imperfecta) murine bones. Mineral orientation distribution functions show that mineral crystallites are not as well aligned (p<0.05) in oim∕oim bones (28±3 deg) compared to wild-type bones (22±3 deg), in agreement with small-angle X-ray scattering results. In wild-type mice, backbone carbonyl orientation is 76±2 deg and in oim∕oim mice, it is 72±4 deg (p>0.05). We provide evidence that simultaneous quantitative measurements of mineral and collagen orientations on intact bone specimens are possible using polarized Raman spectroscopy. PMID:20615030

  10. Quantitative polarized Raman spectroscopy in highly turbid bone tissue

    NASA Astrophysics Data System (ADS)

    Raghavan, Mekhala; Sahar, Nadder D.; Wilson, Robert H.; Mycek, Mary-Ann; Pleshko, Nancy; Kohn, David H.; Morris, Michael D.

    2010-05-01

    Polarized Raman spectroscopy allows measurement of molecular orientation and composition and is widely used in the study of polymer systems. Here, we extend the technique to the extraction of quantitative orientation information from bone tissue, which is optically thick and highly turbid. We discuss multiple scattering effects in tissue and show that repeated measurements using a series of objectives of differing numerical apertures can be employed to assess the contributions of sample turbidity and depth of field on polarized Raman measurements. A high numerical aperture objective minimizes the systematic errors introduced by multiple scattering. We test and validate the use of polarized Raman spectroscopy using wild-type and genetically modified (oim/oim model of osteogenesis imperfecta) murine bones. Mineral orientation distribution functions show that mineral crystallites are not as well aligned (p<0.05) in oim/oim bones (28+/-3 deg) compared to wild-type bones (22+/-3 deg), in agreement with small-angle X-ray scattering results. In wild-type mice, backbone carbonyl orientation is 76+/-2 deg and in oim/oim mice, it is 72+/-4 deg (p>0.05). We provide evidence that simultaneous quantitative measurements of mineral and collagen orientations on intact bone specimens are possible using polarized Raman spectroscopy.

  11. Analysis of light scattered by turbid media in cylindrical geometry.

    PubMed

    Tromp, R Hans; Liemert, André; Meinders, Marcel B J

    2014-07-22

    The angle dependence of the transmitted light through a cylindrical turbid sample (latex suspension, developing milk gel, draining/coarsening milk, and protein foams) in a standard light scattering setup was analyzed in terms of the transport mean free path length or scattering length l* (a measure for the turbidity) and the absorption length labs. By variation of the concentration of an absorbing dye, the independence of l* and labs was demonstrated. The resulting value of the specific extinction coefficient of the dye was found to be in fair agreement with direct spectroscopic determination and practically identical in milk and latex suspensions. The validity of this technique for obtaining l* was demonstrated by monitoring the acid-induced gelation of milk. The possibility to simultaneously determine l* and labs was used to follow the time development of a draining and coarsening protein foam which contained an absorbing dye. It was shown that labs can be used as a measure for the volume fraction of air in the foam. This method of monitoring the transmission of multiple light scattering provides an easy way to determine l* and, specifically for foams, quantitative data dominated by the bulk of the foam.

  12. Modeling scattering in turbid media using the Gegenbauer phase function

    NASA Astrophysics Data System (ADS)

    Calabro, Katherine W.; Cassarly, William

    2015-03-01

    The choice of scattering phase function is critically important in the modeling of photon propagation in turbid media, particularly when the scattering path within the material is on the order of several mean free path lengths. For tissue applications, the single parameter Henyey-Greenstein (HG) phase function is known to underestimate the contribution of backscattering, while phase functions based on Mie theory can be more complex than necessary due to the multitude of parameter inputs. In this work, the two term Gegenbauer phase function is highlighted as an effective compromise between HG and Mie, as demonstrated when fitting the various phase function to measured data from phantom materials. Further comparison against the Modified Henyey-Greenstein (MHG) phase function, another two term function, demonstrates that the Gegenbauer function provides better control of the higher order phase function moments, and hence allows for a wider range of values for the similarity parameter, γ. Wavelength dependence of the Gegenbauer parameters is also investigated using a range of theoretical particle distributions. Finally, extraction of the scattering properties of solid turbid samples from angularly resolved transmission measurements is performed using an iterative Monte Carlo optimization technique. Fitting results using Gegenbauer, HG, MHG, and Mie phase functions are compared.

  13. Spatial Variability of Near Shore Turbidity At Lake Tahoe

    NASA Astrophysics Data System (ADS)

    McConnell, J.; Taylor, K.

    2001-12-01

    The turbidity of the near shore zone at Lake Tahoe has been mapped during different seasons. While the turbidity values are consistently low by comparison to most lakes, there are significant turbidity differences between different locations and seasons. Prior to the start of the 2001 spring runoff the turbidity values where low, except for around Tahoe Keys were large changes to the surface drainage patterns have an adverse influence on the lake. Early in the summer of 2001 high turbidity was observed off the community of South Lake Tahoe and there is a suggestion of a moderate turbidity plume moving along the South East shore. In late summer of 2000, high turbidity areas were noted offshore of areas with developed land. Identification of persistent high turbidity areas can help direct where restoration efforts will be most effective. Repeat turbidity surveys can help assess the effectiveness of restoration efforts. Analysis of the temporal and spatial patterns of turbidity can suggest the location of sources and transportation pathways of undesirable material that enters the lake.

  14. Monitoring of event based mobilization of hydrophobic pollutants in rivers: Calibration of turbidity as a proxy for particle facilitated transport

    NASA Astrophysics Data System (ADS)

    Rügner, Hermann; Schwientek, Marc; Grathwohl, Peter

    2014-05-01

    Transport of many pollutants in rivers is coupled to transport of suspended particles which is typically enhanced during events such as floods, snow melts etc. As the amount of total suspended solids (TSS) in rivers can be monitored by turbidity measurements this may be used as a proxy for the total concentration of particle associated pollutants in rivers such as polycyclic aromatic hydrocarbons (PAHs), PCBs, etc. and several heavy metals. On-line turbidity measurements (e.g. by optical backscattering sensors) then allow for an assessment of particle and pollutant flux dynamics. In this study, pronounced flood and thus turbidity events were sampled at high temporal resolution in three contrasting catchments in Southwest Germany (Rivers Ammer, Goldersbach, Steinlach) as well as in the River Neckar. Samples were analyzed for turbidity, the total amount of PAH and total suspended solids (TSS) in water. Additionally, the grain size distributions of suspended solids were determined. Discharge and turbidity were measured on-line at gauging stations in three of the catchments. Results showed that turbidity and TSS were linearly correlated over an extended turbidity range up to 2000 NTU for the flood samples (i.e. independent on grain size). This also holds for total PAH concentrations which can be reasonably well predicted based on the turbidity measurements and TSS versus PAH relationships - even for very high turbidity or TSS values (> 2000 NTU or mg l-1, respectively). From these linear regressions concentrations of PAHs on suspended particles were obtained which varied by catchment. The values comprise a robust measure of the average sediment quality in a river network and may be correlated to the degree of urbanization represented by the number of inhabitants per total flux of suspended particles. Based on long-term on-line turbidity measurements mass flow rates of particle bound pollutants over time could be calculated. Results showed that by far the largest amount

  15. 40 CFR 141.22 - Turbidity sampling and analytical requirements.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... requirements. 141.22 Section 141.22 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) WATER PROGRAMS (CONTINUED) NATIONAL PRIMARY DRINKING WATER REGULATIONS Monitoring and Analytical Requirements... pursuant to section 1412(b)(7)(iii), that filtration is required. The requirements in this section apply...

  16. 40 CFR 141.22 - Turbidity sampling and analytical requirements.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... requirements. 141.22 Section 141.22 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) WATER PROGRAMS (CONTINUED) NATIONAL PRIMARY DRINKING WATER REGULATIONS Monitoring and Analytical Requirements... pursuant to section 1412(b)(7)(iii), that filtration is required. The requirements in this section apply...

  17. 40 CFR 141.22 - Turbidity sampling and analytical requirements.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... requirements. 141.22 Section 141.22 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) WATER PROGRAMS (CONTINUED) NATIONAL PRIMARY DRINKING WATER REGULATIONS Monitoring and Analytical Requirements... pursuant to section 1412(b)(7)(iii), that filtration is required. The requirements in this section apply...

  18. 40 CFR 141.22 - Turbidity sampling and analytical requirements.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... requirements. 141.22 Section 141.22 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) WATER PROGRAMS (CONTINUED) NATIONAL PRIMARY DRINKING WATER REGULATIONS Monitoring and Analytical Requirements... pursuant to section 1412(b)(7)(iii), that filtration is required. The requirements in this section apply...

  19. Particulate Backscattering Retrieval from Remotely-Sensed Turbidity in Various Coastal and Riverine Turbid Waters

    NASA Astrophysics Data System (ADS)

    Nechad, Bouchra; Dogliotti, Ana; Ruddick, Kevin; Doxaran, David

    2016-08-01

    The semi-empirical algorithm of [1] for the estimation of turbidity (T) from marine reflectance (ρw) is calibrated and validated using a large dataset of in situ measurements collected in various waters, for use with any ocean colour hyperspectral sensor, and with Sentinel-2, Landsat 8 and Pléiades spectral bands. The relationship between particulate backscattering coefficient (bbp) and side-scattering (T) is investigated through simulation of Fournier-Forand phase functions, assuming variable particles size and composition, and through T and bbp in situ measurements in clear to extremely turbid waters.

  20. Turbidity currents generated by Hurricane Iwa

    USGS Publications Warehouse

    Dengler, A.T.; Wilde, P.; Noda, E.K.; Normark, W.R.

    1984-01-01

    Off southwest Oahu, Hawaii, an array of current sensors recorded four successive episodes of downslope displacement associated with high-speed near-bottom currents of up to 200 cm/s and elevated water temperatures. These episodes coincided with the maximum storm effects of hurricane Iwa. Sensors from four moorings recorded increases in depth of as much as 220 m, implying downslope movement of as much as 2.4 km at speeds up to 300 cm/s. A succession of slope failures at or above the 110-m shelf break, each resulting in a turbidity current event, is the favored explanation. ?? 1984 Springer-Verlag New York Inc.

  1. Absorption coefficient instrument for turbid natural waters

    NASA Astrophysics Data System (ADS)

    Friedman, E.; Cherdak, A.; Poole, L.; Houghton, W.

    1980-05-01

    The paper presents an instrument that directly measures multispectral absorption coefficient of turbid natural water. Attention is given to the design, which is shown to incorporate methods for the compensation of variation in the internal light source intensity, correction of the spectrally dependent nature of the optical elements, and correction for variation in the background light level. In addition, when used in conjunction with a spectrally matched total attenuation instrument, the spectrally dependent scattering coefficient can also be derived. Finally, it is reported that systematic errors associated with multiple scattering have been estimated using Monte Carlo techniques.

  2. Absorption coefficient instrument for turbid natural waters

    NASA Technical Reports Server (NTRS)

    Friedman, E.; Cherdak, A.; Poole, L.; Houghton, W.

    1980-01-01

    The paper presents an instrument that directly measures multispectral absorption coefficient of turbid natural water. Attention is given to the design, which is shown to incorporate methods for the compensation of variation in the internal light source intensity, correction of the spectrally dependent nature of the optical elements, and correction for variation in the background light level. In addition, when used in conjunction with a spectrally matched total attenuation instrument, the spectrally dependent scattering coefficient can also be derived. Finally, it is reported that systematic errors associated with multiple scattering have been estimated using Monte Carlo techniques.

  3. Distribution of Turbidity in Australian Tropical Waters

    DTIC Science & Technology

    1993-08-01

    south of 11°S and within 20 to 25 n.miles of the coast of the Cape York Peninsula. Approaches to Darwin (Map 8) Secchi depths less than 5 m have been...found around the south-west corner of Bathurst Island, and in the south-east of Beagle Gulf (the gulf between Bathurst/’Melville Islands and Darwin ...Within 20 n.miles of Darwin Secchi depths as low as 2 m are common. LANDSAT satellite imagery indicates that waters are highly turbid out to

  4. An investigation of atmospheric turbidity over Kerkennah Island in Tunisia

    NASA Astrophysics Data System (ADS)

    Trabelsi, A.; Masmoudi, M.

    2011-07-01

    Atmospheric turbidity is an important parameter for assessing the air pollution in local areas and controlling the attenuation of solar radiation reaching the Earth's surface under cloudless sky. An investigation of atmospheric turbidity has been undertaken in Kerkennah Island (in Tunisia). Turbidity indexes, namely, Linke factor (T L) and Angstrom coefficient (β) were derived directly from measurements taken by pyrheliometer during a year: July (2008) to June (2009). Data obtained from these measurements in this area were compared with measurements performed in a coastal and urban region (Sidi Bou Said) located in the North of Tunisia. A comparison of the seasonal cycle of turbidity at both sites showed: *) maximum values of turbidity in the summer due to dust storms, vertical convection and breeze sea circulation; *) Values of turbidity decrease in the autumn season, due to the decreasing of days of Sirocco and to the increasing of amount of rainfall; *) low values of turbidity index in the winter, due to precipitation removal as well as relative humidity-impacted deposition; *) middle values of turbidity were observed in the spring season. Monthly, diurnal, hourly mean values and frequency of occurrence of the value of each turbidity index were used to characterize variations of atmospheric turbidity. The three-hourly standard meteorological data given by the Meteorological National Institute (Sfax) represent a valuable supplement to the data sets with the pyrheliometer measurements. The analysis of the results shows that there is a high correlation between atmospheric turbidity and local weather conditions, especially temperature and wind speed. The correlation of meteorological parameters (wind speed and temperature) with the turbidity coefficients was analyzed and discussed.

  5. Optimisation of the zinc sulphate turbidity test for the determination of immune status.

    PubMed

    Hogan, I; Doherty, M; Fagan, J; Kennedy, E; Conneely, M; Crowe, B; Lorenz, I

    2016-02-13

    Failure of passive transfer of maternal immunity occurs in calves that fail to absorb sufficient immunoglobulins from ingested colostrum. The zinc sulphate turbidity test has been developed to test bovine neonates for this failure. The specificity of this test has been shown to be less than ideal. The objective was to examine how parameters of the zinc sulphate turbidity test may be manipulated in order to improve its diagnostic accuracy. One hundred and five blood samples were taken from calves of dairy cows receiving various rates of colostrum feeding. The zinc sulphate turbidity test was carried out multiple times on each sample, varying the solution strength, time of reaction and wavelength of light used and the results compared with those of a radial immunodiffusion test, which is the reference method for measuring immunoglobulin concentration in serum. Reducing the time over which the reaction occurs, or increasing the wavelength of light used to read the turbidity, resulted in decreased specificity without improving sensitivity. Increasing the concentration of the zinc sulphate solution used in the test was shown to improve the specificity without decreasing sensitivity. Examination of the cut-off points suggested that a lower cut-off point would improve the performance.

  6. Time- and space-resolved reflectance from multilayered turbid media

    NASA Astrophysics Data System (ADS)

    Gelebart, Bernard; Tualle, Jean-Michel; Tinet, Eric; Avrillier, Sigrid; Ollivier, Jean-Pierre

    1998-01-01

    Our purpose is to develop an optical technique for in-vivo and non-invasive diagnosis using backscattered light measurements. We have already demonstrated that optical coefficients of turbid media ((mu) a, (mu) s) can be derived from time and space-resolved reflectance in the case of semi-infinite geometry. This procedure was then applied to the investigation of multi-layered media: the upper layer was an aqueous solution of calibrated latex microspheres in water and the lower layer of the sample was a solid phantom. Two different types of phantoms were used. In the first set of experiments, we used an absorbing medium for under layer. In the second case, the lower layer was an absorbing and scattering phantom. Comparison with Monte-Carlo simulations were achieved for the resolution of the inverse problem.

  7. Chapter A6. Section 6.7. Turbidity

    USGS Publications Warehouse

    Anderson, Chauncey W.

    2005-01-01

    Turbidity is one of the indicators used to assess the environmental health of water bodies. Turbidity is caused by the presence of suspended and dissolved matter, such as clay, silt, finely divided organic matter, plankton and other microscopic organisms, organic acids, and dyes. This section of the National Field Manual (NFM) describes the USGS protocols for determining turbidity in surface and ground waters, including extensive guidance for equipment selection and data reporting. It includes the revised approach to turbidity measurement and reporting that was implemented by the U.S. Geological Survey (USGS) in October 2004 to account for technological advances and consequent measurement complexities.

  8. Unusual behaviour of phototrophic picoplankton in turbid waters

    PubMed Central

    Pálffy, Károly; V. -Balogh, Katalin; Botta-Dukát, Zoltán; Vörös, Lajos

    2017-01-01

    Autotrophic picoplankton (APP) abundance and contribution to phytoplankton biomass was studied in Hungarian shallow lakes to test the effect of inorganic turbidity determining the size distribution of the phytoplankton. The studied lakes displayed wide turbidity (TSS: 4–2250 mg l-1) and phytoplankton biomass (chlorophyll a: 1–460 μg l-1) range, as well as APP abundance (0 and 100 million cells ml-1) and contribution (0–100%) to total phytoplankton biomass. Inorganic turbidity had a significant effect on the abundance and contribution of APP, resulting in higher values compared to other freshwater lakes with the same phytoplankton biomass. Our analysis has provided empirical evidence for a switching point (50 mg l-1 inorganic turbidity), above which turbidity is the key factor causing APP predominance regardless of phytoplankton biomass in shallow turbid lakes. Our results have shown that turbid shallow lakes are unique waters, where the formerly and widely accepted model (decreasing APP contribution with increasing phytoplankton biomass) is not applicable. We hypothesize that this unusual behaviour of APP in turbid waters is a result of either diminished underwater light intensity or a reduced grazing pressure due to high inorganic turbidity. PMID:28346542

  9. Anisotropic reflectance from turbid media. I. Theory.

    PubMed

    Neuman, Magnus; Edström, Per

    2010-05-01

    It is shown that the intensity of light reflected from plane-parallel turbid media is anisotropic in all situations encountered in practice. The anisotropy, in the form of higher intensity at large polar angles, increases when the amount of near-surface bulk scattering is increased, which dominates in optically thin and highly absorbing media. The only situation with isotropic intensity is when a non-absorbing infinitely thick medium is illuminated diffusely. This is the only case where the Kubelka-Munk model gives exact results and there exists an exact translation between Kubelka-Munk and general radiative transfer. This also means that a bulk scattering perfect diffusor does not exist. Angle-resolved models are thus crucial for a correct understanding of light scattering in turbid media. The results are derived using simulations and analytical calculations. It is also shown that there exists an optimal angle for directional detection that minimizes the error introduced when using the Kubelka-Munk model to interpret reflectance measurements with diffuse illumination.

  10. Multi-faceted monitoring of estuarine turbidity and particulate matter provenance: Case study from Salem Harbor, USA.

    PubMed

    Hubeny, J Bradford; Kenney, Melanie; Warren, Barbara; Louisos, Jeremy

    2017-01-01

    Turbidity is a water quality parameter that is known to adversely affect aquatic systems, however the causes of turbid water are often elusive. We present results of a study designed to constrain the source of particulate matter in a coastal embayment that has suffered from increased turbidity over past decades. Our approach utilized monitoring buoys to quantify turbidity at high temporal resolution complemented by geochemical isotope analysis of suspended sediment samples and meteorological data. Results reveal a complex system in which multiple sources are associated with particulate matter. Weight of evidence demonstrates that phytoplankton productivity in the water column, however, is the dominant source of particulate matter associated with elevated turbidity in Salem Harbor, Massachusetts. Allochthonous matter from the watershed was observed to mix into the pool of suspended particulate matter near river mouths, especially in spring and summer. Resuspension of harbor surface sediments likely provides additional particulates in the regions of boat moorings, especially during summer when recreational boats are attached to moorings. Our approach allows us to constrain the causes of turbidity events in this embayment, is helping with conservation efforts of environmental quality in the region, and can be used as a template for other locations.

  11. Estimation of turbidity in coastal waters using satellite data

    NASA Astrophysics Data System (ADS)

    Kulshreshtha, Anuj; Shanmugam, Palanisamy

    2016-05-01

    The assessment of water clarity of any regional water body is particularly important from ecological and water quality perspectives, especially in the regions which are highly influenced by sediment run-off and seasonal fluctuations in turbidity. The ocean colour remote sensing has played a significant role in monitoring the turbidity level in marine and inland water bodies. However, algorithms to accurately estimate the turbidity in such optically complex waters are scarce or limited by high level of uncertainty due to various issues. The present study proposes a simple, two band algorithm to estimate turbidity in both turbid and clear waters. It was found that the band ratio of remote sensing reflectance (Rrs(670)/Rrs(670)+Rrs(555)) represents the proxy of TSS (Total suspended sediment) and therefore, positively correlates to turbidity. The new algorithm is based on the assumption that light reflected in these two vital bands contains the essential information regarding the total suspended matter in the water column. The statistical results showed that the percent mean relative error between the predicted turbidity and the measured turbidity was within +/-20%. To further demonstrate the robustness of the present algorithm, the spatial grid contours for the measured and the predicted turbidity was generated for the month of January 2014, August 2013 and May 2012 for the coastal waters in Bay of Bengal (Point Calimere, located in the southeast coast of India). The close consistency between the predicted and measured turbidity spatial patterns revealed that the present algorithm can be applied with high confidence to predict turbidity in both coastal and inland waters.

  12. Suspended-sediment and turbidity responses to sediment and turbidity reduction projects in the Beaver Kill, Stony Clove Creek, and Warner Creek, Watersheds, New York, 2010–14

    USGS Publications Warehouse

    Siemion, Jason; McHale, Michael R.; Davis, Wae Danyelle

    2016-12-05

    Suspended-sediment concentrations (SSCs) and turbidity were monitored within the Beaver Kill, Stony Clove Creek, and Warner Creek tributaries to the upper Esopus Creek in New York, the main source of water to the Ashokan Reservoir, from October 1, 2010, through September 30, 2014. The purpose of the monitoring was to determine the effects of suspended-sediment and turbidity reduction projects (STRPs) on SSC and turbidity in two of the three streams; no STRPs were constructed in the Beaver Kill watershed. During the study period, four STRPs were completed in the Stony Clove Creek and Warner Creek watersheds. Daily mean SSCs decreased significantly for a given streamflow after the STRPs were completed. The most substantial decreases in daily mean SSCs were measured at the highest streamflows. Background SSCs, as measured in water samples collected in upstream reference stream reaches, in all three streams in this study were less than 5 milligrams per liter during low and high streamflows. Longitudinal stream sampling identified stream reaches with failing hillslopes in contact with the stream channel as the primary sediment sources in the Beaver Kill and Stony Clove Creek watersheds.

  13. Prey capture of pike Esox lucius larvae in turbid water.

    PubMed

    Salonen, M; Engström-Ost, J

    2010-06-01

    Pike Esox lucius larvae captured fewer calanoid and cyclopoid copepods in turbid than in clear water, whereas no differences were detected in feeding rates on Daphnia longispina. Decreased capture of copepods may lead to lower growth and survival of E. lucius larvae in turbid areas, in particular, if cladocerans are scarce.

  14. 40 CFR 141.13 - Maximum contaminant levels for turbidity.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... turbidity. 141.13 Section 141.13 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) WATER PROGRAMS (CONTINUED) NATIONAL PRIMARY DRINKING WATER REGULATIONS Maximum Contaminant Levels § 141.13... part. The maximum contaminant levels for turbidity in drinking water, measured at a...

  15. 40 CFR 141.13 - Maximum contaminant levels for turbidity.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... turbidity. 141.13 Section 141.13 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) WATER PROGRAMS (CONTINUED) NATIONAL PRIMARY DRINKING WATER REGULATIONS Maximum Contaminant Levels § 141.13... part. The maximum contaminant levels for turbidity in drinking water, measured at a...

  16. 40 CFR 141.13 - Maximum contaminant levels for turbidity.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... turbidity. 141.13 Section 141.13 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) WATER PROGRAMS (CONTINUED) NATIONAL PRIMARY DRINKING WATER REGULATIONS Maximum Contaminant Levels § 141.13... part. The maximum contaminant levels for turbidity in drinking water, measured at a...

  17. In-situ measurements of velocity structure within turbidity currents

    USGS Publications Warehouse

    Xu, J. P.; Noble, M.A.; Rosenfeld, L.K.

    2004-01-01

    Turbidity currents are thought to be the main mechanism to move ???500,000 m3 of sediments annually from the head of the Monterey Submarine Canyon to the deep-sea fan. Indirect evidence has shown frequent occurrences of such turbidity currents in the canyon, but the dynamic properties of the turbidity currents such as maximum speed, duration, and dimensions are still unknown. Here we present the first-ever in-situ measurements of velocity profiles of four turbidity currents whose maximum along-canyon velocity reached 190 cm/s. Two turbidity currents coincided with storms that produced the highest swells and the biggest stream flows during the year-long deployment. Copyright 2004 by the American Geophysical Union.

  18. Monitoring instream turbidity to estimate continuous suspended-sediment loads and yields and clay-water volumes in the upper North Santiam River Basin, Oregon, 1998-2000

    USGS Publications Warehouse

    Uhrich, Mark A.; Bragg, Heather M.

    2003-01-01

    Three real-time, instream water-quality and turbidity-monitoring sites were established in October 1998 in the upper North Santiam River Basin on the North Santiam River, the Breitenbush River, and Blowout Creek, the main tributary inputs to Detroit Lake, a large, controlled reservoir that extends from river mile 61 to 70. Suspended-sediment samples were collected biweekly to monthly at each station. Rating curves provided estimated suspended-sediment concentration in 30-minute increments from log transformations of the instream turbidity monitoring data. Turbidity was found to be a better surrogate than discharge for estimating suspended-sediment concentration. Daily and annual mean suspended-sediment loads were estimated using the estimated suspended-sediment concentrations and corresponding streamflow data. A laboratory method for estimating persistent (residual) turbidity from separate turbidity samples was developed. Turbidity was measured over time for each sample. Turbidity decay curves were derived as the suspended sediment settled. Each curve was used to estimate a turbidity value for a given settling time. Medium to fine clay particle (< 0.002 mm [millimeter] diameter) settling times of 8.5 hours were computed using Stokes Law. An average of 30 persistent turbidity samples was collected from each of the 3 sites. These samples were used to estimate the 0.002-mm-size clay particle persistent turbidity for each site. The monitored instream 30-minute turbidity values were converted to a calculated persistent turbidity value that would have resulted after 8.5 hours of settling in the laboratory. Persistent turbidities of 10 NTU and above were tabulated for each site. (Water of 10 NTU and above can interfere with or damage treatment filters and result in intake closures at drinking-water facilities.) A method was developed that used the persistent turbidity experiments, turbidity decay curves, and stream discharge to estimate the volume of water containing

  19. Development of turbidity estimation model using SMA and water turbidity index Application to the Kushiro Mire, japan--

    NASA Astrophysics Data System (ADS)

    Kameyama, S.; Yamagata, Y.; Nakamura, F.; Kaneko, M.

    2003-04-01

    A new Water Turbidity Index (WTI) based on multi spectral images was developed and tested at The Kushiro Mire, the largest mire in Japan.The Kushiro Mire designated by the Ramsar Convention in 1980, presently faces a serious problem with turbid water flooding. Shortening of stream channels, associated with agricultural development, is a major cause of streambed aggradations. The aggradation reduces the carrying capacity of the channel, resulting in sediment-laden water spilling over into the wetlands during a flood event. An algorithm for turbidity estimation was developed and applied to Landsat TM images to monitor the turbid water on the mire surface during the snow-melting season. We used Spectral Mixture Analysis (SMA) to produce a turbidity estimation model. The SMA 'unmixes' a mixed pixel determining the fractions due to each spectral endmember. In this study we used four endmembers (1. alder, 2. reed, 3. high- concentration turbid water (485ppm), 4. low- concentration turbid water (10ppm) measured in the test site. The WTI was determined by the following equation: WTI = amax / ( amax + amin ), where amax is abundance of high- concentration turbid water and amin is abundance of low- concentration turbid water. The endmember spectra of alder and reed were measured in the laboratory using specimens collected at the test site. The spectrum of turbid water was measured at the test sites. The relative abundance of each endmember was estimated based on this spectral information using SMA. The same formula was applied to Landsat TM images. Then we applied the WTI equation to the endmember images to obtain a WTI map. In the mire wetland region, turbid water spreads under alder trees and reed grasses. To verify our turbidity estimation method based on WTI under these conditions, we constructed a small experimental wetland consisting of mixed stands of alder and reed. WTI was calculated from the mixed spectrum of this "artificial wetland" and the regression curve for

  20. Performance Evaluation of Five Turbidity Sensors in Three Primary Standards

    USGS Publications Warehouse

    Snazelle, Teri T.

    2015-10-28

    Open-File Report 2015-1172 is temporarily unavailable.Five commercially available turbidity sensors were evaluated by the U.S. Geological Survey, Hydrologic Instrumentation Facility (HIF) for accuracy and precision in three types of turbidity standards; formazin, StablCal, and AMCO Clear (AMCO–AEPA). The U.S. Environmental Protection Agency (EPA) recognizes all three turbidity standards as primary standards, meaning they are acceptable for reporting purposes. The Forrest Technology Systems (FTS) DTS-12, the Hach SOLITAX sc, the Xylem EXO turbidity sensor, the Yellow Springs Instrument (YSI) 6136 turbidity sensor, and the Hydrolab Series 5 self-cleaning turbidity sensor were evaluated to determine if turbidity measurements in the three primary standards are comparable to each other, and to ascertain if the primary standards are truly interchangeable. A formazin 4000 nephelometric turbidity unit (NTU) stock was purchased and dilutions of 40, 100, 400, 800, and 1000 NTU were made fresh the day of testing. StablCal and AMCO Clear (for Hach 2100N) standards with corresponding concentrations were also purchased for the evaluation. Sensor performance was not evaluated in turbidity levels less than 40 NTU due to the unavailability of polymer-bead turbidity standards rated for general use. The percent error was calculated as the true (not absolute) difference between the measured turbidity and the standard value, divided by the standard value.The sensors that demonstrated the best overall performance in the evaluation were the Hach SOLITAX and the Hydrolab Series 5 turbidity sensor when the operating range (0.001–4000 NTU for the SOLITAX and 0.1–3000 NTU for the Hydrolab) was considered in addition to sensor accuracy and precision. The average percent error in the three standards was 3.80 percent for the SOLITAX and -4.46 percent for the Hydrolab. The DTS-12 also demonstrated good accuracy with an average percent error of 2.02 percent and a maximum relative standard

  1. Evaluation of the dual differential radiometer for remote sensing of sediment and chlorophyll in turbid waters

    NASA Technical Reports Server (NTRS)

    Witte, W. G.

    1975-01-01

    The dual differential radiometer (DDR) was tested to determine its capability for measuring suspended sediment and chlorophyll in turbid waters. Measurements were obtained from a boat dock and from a helicopter with combinations of sample and reference filters with peak transmissions at various wavelengths. Water samples were taken concurrently and were analyzed for light scattering, particle count, and total chlorophyll. Least-squares estimates of the linear relationship between DDR output and the water parameters yielded correlation coefficients of less than 0.7. Under the turbid water conditions of the present tests, the DDR did not accurately measure either suspended sediment or chlorophyll. A precise knowledge of the spectral signatures of various pollutants might enable appropriate filters to be selected for tuning the DDR to monitor a particular pollutant.

  2. Calculation of sky turbidity in the Kingdom of Saudi Arabia

    NASA Astrophysics Data System (ADS)

    Al-Mostafa, Z. A.

    The atmospheric turbidity has been calculated and averaged for 29 places around the Kingdom of Saudi Arabia by using a nine years solar radiation data covering the period from 1971 to 1980. The turbidity values were found to range from 0.1 to 0.4, and the overall average of the turbidity was 0.281±0.056. The minimum value was in Sirr-Lasan (0.168±0.028) and the maximum value was 0.474±0.090 in Riyadh. The low value of the turbidity indicates that the sky of Sirr-Lasan (2100 meter above sea level) may be the clearest sky in the country if the turbidity is taken to be the main factor in preliminary site selection for astronomical observatory. Correlations between the turbidity and geographical coordinates have been investigated and have shown a weak relation between them. Also, seasonal variations studies have shown no significant distribution, which means that each station has its own trend. The low values of the turbidity indicate that the Saudi Arabian sky has relatively small disturbance in the atmosphere.

  3. Uncertainties in turbidity-based measurements of suspended sediment load used to quantify the sediment budget on the catchment scale

    NASA Astrophysics Data System (ADS)

    de Hipt, Felix Op; Diekkrüger, Bernd; Steup, Gero; Rode, Michael

    2016-04-01

    Water-driven soil erosion, transport and deposition take place on different spatial and temporal scales. Therefore, related measurements are complex and require process understanding and a multi-method approach combining different measurement methods with soil erosion modeling. Turbidity as a surrogate measurement for suspended sediment concentration (SSC) in rivers is frequently used to overcome the disadvantages of conventional sediment measurement techniques regarding temporal resolution and continuity. The use of turbidity measurements requires a close correlation between turbidity and SSC. Depending on the number of samples collected, the measured range and the variations in the measurements, SSC-turbidity curves are subject to uncertainty. This uncertainty has to be determined in order to assess the reliability of measure-ments used to quantify catchment sediment yields and to calibrate soil erosion models. This study presents the calibration results from a sub-humid catchment in south-western Burkina Faso and investigates the related uncertainties. Daily in situ measurements of SSC manually collected at one turbidity station and the corresponding turbidity readings are used to obtain the site-specific calibration curve. The discharge is calculated based on an empirical water level-discharge relationship. The derived regression equations are used to define prediction intervals for SSC and discharge. The uncertainty of the suspended sediment load time series is influenced by the corresponding uncertainties of SSC and discharge. This study shows that the determination of uncertainty is relevant when turbidity-based measurements of suspended sediment loads are used to quantify catchment erosion and to calibrate erosion models.

  4. Monitoring of event-based mobilization of hydrophobic pollutants in rivers: calibration of turbidity as a proxy for particle facilitated transport in field and laboratory.

    PubMed

    Rügner, Hermann; Schwientek, Marc; Egner, Marius; Grathwohl, Peter

    2014-08-15

    Transport of many pollutants in rivers is coupled to mobilization of suspended particles which typically occurs during floods. Since the amount of total suspended solids (TSS) in rivers can be monitored by turbidity measurements this may be used as a proxy for the total concentration of particle associated pollutants such as PAHs, PCBs, etc. and several heavy metals. Online turbidity measurements (e.g. by optical backscattering sensors) would then also allow for an assessment of particle and pollutant flux dynamics if once calibrated against TSS and total pollutant concentrations for a given catchment. In this study, distinct flood and thus turbidity events were sampled at high temporal resolution in three contrasting sub-catchments of the River Neckar in Southwest Germany (Ammer, Goldersbach, Steinlach) as well as in the River Neckar itself and investigated for the total amount of PAHs and TSS in water; turbidity (NTU) and grain size distributions of suspended solids were determined as well. Laboratory experiments were performed with natural river bed sediments from different locations (Ammer) to investigate PAH concentrations, TSS and turbidity during sedimentation of suspended particles under controlled conditions (yielding smaller and smaller suspended particles and TSS with time). Laboratory and field results agreed very well and showed that turbidity and TSS were linearly correlated over an extended turbidity range up to 2000 NTU for the field samples and up to 8000 NTU in lab experiments. This also holds for total PAH concentrations which can be reasonably well predicted based on turbidity measurements and TSS vs. PAHs relationships - even for high turbidity values observed during flood events (>2000 NTU). Total PAH concentrations on suspended solids were independent of grain size of suspended particles. This implies that for the rivers investigated the sorption capacity of particles did not change significantly during the observed events.

  5. Quantitative generalized ratiometric fluorescence spectroscopy for turbid media based on probe encapsulated by biologically localized embedding.

    PubMed

    Yan, Xiu-Fang; Chen, Zeng-Ping; Cui, Yin-Yin; Hu, Yuan-Liang; Yu, Ru-Qin

    2016-05-19

    PEBBLE (probe encapsulated by biologically localized embedding) nanosensor encapsulating an intensity-based fluorescence indicator and an inert reference fluorescence dye inside the pores of stable matrix can be used as a generalized wavelength-ratiometric probe. However, the lack of an efficient quantitative model render the choices of inert reference dyes and intensity-based fluorescence indicators used in PEBBLEs based generalized wavelength-ratiometric probes rather limited. In this contribution, an extended quantitative fluorescence model was derived specifically for generalized wavelength-ratiometric probes based on PEBBLE technique (QFMGRP) with a view to simplify the design of PEBBLEs and hence further extend their application potentials. The effectiveness of QFMGRP has been tested on the quantitative determination of free Ca(2+) in both simulated and real turbid media using a Ca(2+) sensitive PEBBLE nanosensor encapsulating Rhod-2 and eosin B inside the micropores of stable polyacrylamide matrix. Experimental results demonstrated that QFMGRP could realize precise and accurate quantification of free Ca(2+) in turbid samples, even though there is serious overlapping between the fluorescence excitation peaks of eosin B and Ca(2+) bound Rhod-2. The average relative predictive error value of QFMGRP for the test simulated turbid samples was 5.9%, about 2-4 times lower than the corresponding values of partial least squares calibration model and the empirical ratiometric model based on the ratio of fluorescence intensities at the excitation peaks of Ca(2+) bound Rhod-2 and eosin B. The recovery rates of QFMGRP for the real and spiked turbid samples varied from 93.1% to 101%, comparable to the corresponding results of atomic absorption spectrometry.

  6. Comparison of turbidity to multi-frequency sideways-looking acoustic-Doppler data and suspended-sediment data in the Colorado River in Grand Canyon

    USGS Publications Warehouse

    Voichick, Nicholas; Topping, David J.

    2010-01-01

    Water clarity is important to biologists when studying fish and other fluvial fauna and flora. Turbidity is an indicator of the cloudiness of water, or reduced water clarity, and is commonly measured using nephelometric sensors that record the scattering and absorption of light by particles in the water. Unfortunately, nephelometric sensors only operate over a narrow range of the conditions typically encountered in rivers dominated by suspended-sediment transport. For example, sediment inputs into the Colorado River in Grand Canyon caused by tributary floods often result in turbidity levels that exceed the maximum recording level of nephelometric turbidity sensors. The limited range of these sensors is one reason why acoustic Doppler profiler instrument data, not turbidity, has been used as a surrogate for suspended sediment concentration and load of the Colorado River in Grand Canyon. However, in addition to being an important water-quality parameter to biologists, turbidity of the Colorado River in Grand Canyon has been used to strengthen the suspended-sediment record through the process of turbidity-threshold sampling; high turbidity values trigger a pump sampler to collect samples of the river at critical times for gathering suspended-sediment data. Turbidity depends on several characteristics of suspended sediment including concentration, particle size, particle shape, color, and the refractive index of particles. In this paper, turbidity is compared with other parameters coupled to suspended sediment, namely suspended-silt and clay concentration and multifrequency acoustic attenuation. These data have been collected since 2005 at four stations with different sediment-supply characteristics on the Colorado River in Grand Canyon. These comparisons reveal that acoustic attenuation is a particularly useful parameter, because it is strongly related to turbidity and it can be measured by instruments that experience minimal fouling and record over the entire range

  7. Dynamic imaging through turbid media based on digital holography.

    PubMed

    Li, Shiping; Zhong, Jingang

    2014-03-01

    Imaging through turbid media using visible or IR light instead of harmful x ray is still a challenging problem, especially in dynamic imaging. A method of dynamic imaging through turbid media using digital holography is presented. In order to match the coherence length between the dynamic object wave and the reference wave, a cw laser is used. To solve the problem of difficult focusing in imaging through turbid media, an autofocus technology is applied. To further enhance the image contrast, a spatial filtering technique is used. A description of digital holography and experiments of imaging the objects hidden in turbid media are presented. The experimental result shows that dynamic images of the objects can be achieved by the use of digital holography.

  8. Small-scale turbidity currents in a big submarine canyon

    USGS Publications Warehouse

    Xu, Jingping; Barry, James P.; Paull, Charles K.

    2013-01-01

    Field measurements of oceanic turbidity currents, especially diluted currents, are extremely rare. We present a dilute turbidity current recorded by instrumented moorings 14.5 km apart at 1300 and 1860 m water depth. The sediment concentration within the flow was 0.017%, accounting for 18 cm/s gravity current speed due to density excess. Tidal currents of ∼30 cm/s during the event provided a "tailwind" that assisted the down-canyon movement of the turbidity current and its sediment plume. High-resolution velocity measurements suggested that the turbidity current was likely the result of a local canyon wall slumping near the 1300 m mooring. Frequent occurrences, in both space and time, of such weak sediment transport events could be an important mechanism to cascade sediment and other particles, and to help sustain the vibrant ecosystems in deep-sea canyons.

  9. Effects of flow regime on stream turbidity and suspended solids after wildfire, Colorado Front Range

    USGS Publications Warehouse

    Murphy, Sheila F.; McCleskey, R. Blaine; Writer, Jeffrey H.

    2012-01-01

    Wildfires occur frequently in the Colorado Front Range and can alter the hydrological response of watersheds, yet little information exists on the impact of flow regime and storm events on post-wildfire water quality. The flow regime in the region is characterized by base-flow conditions during much of the year and increased runoff during spring snowmelt and summer convective storms. The impact of snowmelt and storm events on stream discharge and water quality was evaluated for about a year after a wildfire near Boulder, Colorado, USA. During spring snowmelt and low-intensity storms, differences in discharge and turbidity at sites upstream and downstream from the burned areas were minimal. However, high-intensity convective storms resulted in dramatic increases in discharge and turbidity at sites downstream from the burned area. This study highlights the importance of using high-frequency sampling to assess accurately wildfire impacts on water quality downstream.

  10. Dynamics of coarse particulate matter in the turbidity maximum zone of the Gironde Estuary

    NASA Astrophysics Data System (ADS)

    Fuentes-Cid, Ana; Etcheber, Henri; Schmidt, Sabine; Abril, Gwenaël; De-Oliveira, Eric; Lepage, Mario; Sottolichio, Aldo

    2014-01-01

    There is a lack of studies devoted to coarse particulate matter (CPM) in estuaries, although this fraction can disturb activities that filter large volumes of water, such as industrial or fishery activities. In the macrotidal and highly-turbid Gironde Estuary, a monthly sampling of CPM was performed in 2011 and 2013 at two stations in the Turbidity Maximum Zone (TMZ) to understand its seasonal, tidal and hydrological dynamics. Regardless of the season and station, low quantities of CPM (few g m-3) were observed in comparison with suspended particulate matter (several 103 g m-3). The highest concentrations were consistently recorded in bottom waters and at the upstream station. Whereas there is no clear link between the CPM present in the column water and spring or neap tides, an increase in the CPM size has been identified at the two stations after a flood event, fact potentially critical regarding filtering functioning of estuarine activities.

  11. Depolarization of light in turbid media: a scattering event resolved Monte Carlo study.

    PubMed

    Guo, Xinxin; Wood, Michael F G; Ghosh, Nirmalya; Vitkin, I Alex

    2010-01-10

    Details of light depolarization in turbid media were investigated using polarization-sensitive Monte Carlo simulations. The surviving linear and circular polarization fractions of photons undergoing a particular number of scattering events were studied for different optical properties of the turbid media. It was found that the threshold number of photon scattering interactions that fully randomize the incident polarization (defined here as <1% surviving polarization fraction) is not a constant, but varies with the photon detection angle. Larger detection angles, close to backscattering direction, show lower full depolarization threshold number for a given set of sample's optical properties. The Monte Carlo simulations also confirm that depolarization is not only controlled by the number of scattering events and detection geometry, but is also strongly influenced by other factors such as anisotropy g, medium linear birefringence, and the polarization state of the incident light.

  12. Hybrid algorithm for simulating the collimated transmittance of homogeneous stratified turbid media.

    PubMed

    Cruzado, Beatriz Morales; Atencio, José Alberto Delgado; Vázquez Y Montiel, Sergio; Gómez, Erick Sarmiento

    2015-05-01

    In this work we describe the development of a program that simulates the propagation of photons through refractive and reflecting optical components such as lenses, mirrors and stops that includes a biological tissue sample as the main issue to be investigated in order to get a simulated value of light distribution, in particular, of the unscattered light. The analysis of the photons that travel through the sample is based on the program Monte Carlo Multi-Layered with some modifications that consider a Gaussian beam as initial source of light. Position, directional cosines and weight of photons exiting the turbid media are used to propagate them through an optical system. As a mean of validation of the program, we selected a typical optical system for measurement of collimated transmittance. Therefore, several tests were carried out to find the optical system that gives the theoretical collimated transmittance at different values of the optical properties of the turbid media. Along this validation, the optimal experimental configuration is found. Using this results, a comparison between the simulated optimal configuration and the experimental set-up was done, by using a colloidal suspension as a turbid media.

  13. Hybrid algorithm for simulating the collimated transmittance of homogeneous stratified turbid media

    PubMed Central

    Cruzado, Beatriz Morales; Atencio, José Alberto Delgado; Vázquez y Montiel, Sergio; Gómez, Erick Sarmiento

    2015-01-01

    In this work we describe the development of a program that simulates the propagation of photons through refractive and reflecting optical components such as lenses, mirrors and stops that includes a biological tissue sample as the main issue to be investigated in order to get a simulated value of light distribution, in particular, of the unscattered light. The analysis of the photons that travel through the sample is based on the program Monte Carlo Multi-Layered with some modifications that consider a Gaussian beam as initial source of light. Position, directional cosines and weight of photons exiting the turbid media are used to propagate them through an optical system. As a mean of validation of the program, we selected a typical optical system for measurement of collimated transmittance. Therefore, several tests were carried out to find the optical system that gives the theoretical collimated transmittance at different values of the optical properties of the turbid media. Along this validation, the optimal experimental configuration is found. Using this results, a comparison between the simulated optimal configuration and the experimental set-up was done, by using a colloidal suspension as a turbid media. PMID:26137375

  14. 40 CFR 141.21 - Coliform sampling.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... the sample produces a turbid culture in the absence of gas production using an analytical method where gas formation is examined (e.g., the Multiple-Tube Fermentation Technique), produces a turbid culture... total coliform-positive, the system must analyze that total coliform-positive culture medium...

  15. 40 CFR 141.21 - Coliform sampling.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... the sample produces a turbid culture in the absence of gas production using an analytical method where gas formation is examined (e.g., the Multiple-Tube Fermentation Technique), produces a turbid culture... total coliform-positive, the system must analyze that total coliform-positive culture medium...

  16. 40 CFR 141.21 - Coliform sampling.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... the sample produces a turbid culture in the absence of gas production using an analytical method where gas formation is examined (e.g., the Multiple-Tube Fermentation Technique), produces a turbid culture... total coliform-positive, the system must analyze that total coliform-positive culture medium...

  17. Suspended solids in and turbidity of runoff from green roofs.

    PubMed

    Morgan, Susan; Alyaseri, Isam; Retzlaff, William

    2011-01-01

    Green roof technology is used to reduce the quantity of stormwater runoff, but questions remain regarding its impact on quality. This study analyzed the total suspended solids (TSS) in and the turbidity of runoff from green roof growth media mixed with composted pine bark in an indoor pot study. The results showed that there were elevated levels of TSS and turbidity in the runoff that decreased over time for all growth media. Both TSS and turbidity are affected by the type of growth media. Lava and haydite had higher mean TSS and mean turbidity than arkalyte and bottom ash. Vegetation reduced the mean turbidity and mean TSS of the first flush by an average of 53% and 63%, respectively, but generally had no statistically significant effect thereafter. The results indicate that the media, rather than the vegetation, has a greater effect on TSS and turbidity in the runoff In areas with stringent water quality regulations for stormwater runoff from developed sites, media selection may be an important consideration. It may also be necessary in these regions to ensure that the roof is planted prior to receiving rainfall to minimize the first flush effect and that any irrigation does not result in runoff.

  18. Turbidity study of solar ponds utilizing seawater as salt source

    SciTech Connect

    Li, Nan; Sun, Wence; Shi, Yufeng; Yin, Fang; Zhang, Caihong

    2010-02-15

    A series of experiments were conducted to study the turbidity reduction in solar ponds utilizing seawater as salt source. The experiment on the turbidity reduction efficiency with chemicals indicates that alum (KAl(SO{sub 4}){sub 2}.12H{sub 2}O) has a better turbidity control property because of its strongly flocculating and also well depressing the growing of algae and bacteria in the seawater. In comparison with bittern and seawater, our experiment shows that the residual brine after desalination can keep limpidity for a long time even without any chemical in it. Experiments were also conducted on the diffusion of turbidity and salinity, which show that the turbidity did not diffuse upwards in the solution. In the experiment on subsidence of soil in the bittern and saline with the same salinity, it was found that soil subsided quite quickly in the pure saline water, but very slowly in the bittern. In this paper we also proposed an economical method to protect the solar pond from the damage of rain. Finally, thermal performance of a solar pond was simulated in the conditions of different turbidities using a thermal diffusion model. (author)

  19. Spatial and temporal variability of the atmospheric turbidity in Tunisia

    NASA Astrophysics Data System (ADS)

    Saad, Mohamed; Trabelsi, Amel; Masmoudi, Mohamed; Alfaro, Stephane C.

    2016-11-01

    Atmospheric turbidity is an important parameter in meteorology, climatology and for providing hindsight on particulate air pollution in local areas. In this work we exploit 1260 direct solar radiation measurements performed in Sfax (Center Tunisia), from March 2015 to February 2016. These measurements were made with a pyrheliometer only when clouds did not obstruct the solar disk. The atmospheric turbidity is quantified by the means of both the Linke's turbidity factor (TLI) and Angström's coefficient (β). Over the year, values of TLI and β are found to vary in the ranges 1-15 and 0-0.7, with the most probable values around 3.5 and 0.05, respectively. However, a marked seasonal pattern is observed for the two turbidity parameters. They achieve their maximum in the spring and summer months, their minimum in winter and autumn appears as a transitional period. The comparison of the results obtained in Sfax with those of three AERONET stations located in north (Carthage), central-north (Ben Salem), and south (Medenine) Tunisia, reveals that this seasonal pattern of the atmospheric turbidity is valid for all the Tunisian territory, and probably beyond. At shorter (hourly) time scales, the diurnal behavior of the turbidity in Sfax is different in the summer months from the one observed during the rest of the year. Indeed, an enhancement of TLI is observed during the day. This is assumedly attributed to the production of secondary aerosols by atmospheric photochemistry.

  20. Chlorophyll a and turbidity patterns over coral reefs systems of La Parguera Natural Reserve, Puerto Rico.

    PubMed

    Otero, Emesto; Carbery, Kelly K

    2005-05-01

    Studies of temporal and spatial changes in phytoplankton biomass and turbidity provide essential information on coral reef ecosystem function and health. Fluctuation of phytoplankton biomass responds to several factors including nutrient inputs, both anthropogenic and natural, while turbidity is mostly affected by sediment resuspension or transport from terrestrial systems. These parameters can be used as sentinels of significant environmental factors "modifying" coral reef systems. A chlorophyll a concentration (Chl a) and turbidity (Turb) in situ logger was installed at 10 stations from June 4 to July 7, 2003 in La Parguera Natural Reserve (Southwestern Puerto Rico) to assess short-term temporal and geographic variation in patterns of phytoplankton biomass and turbidity at pre-selected sites as part of an interdisciplinary long-term study. Average station Ch1 a variation was 0.17-1.12 microg 1(-1) and 0.2-23.4 NTU for Turb. Results indicate that the western near-coastal stations had higher levels of Turb and Ch1 a. The easternmost mid shelf station, Romero reef, was similar to coastal stations probably due to nutrient and suspended sediment inputs from a source external to our study area to the east, Guánica Bay. Comparisons between different sampling days indicate significant differences between days for most stations suggesting that one-time discrete sampling may not be representative of average water column conditions and illustrate the dynamic nature of coral reef systems. Further work is warranted to assess seasonal changes that integrate short-term (daily) variability in both Turb and Ch1 a.

  1. Establishment of turbidity forecasting model and early-warning system for source water turbidity management using back-propagation artificial neural network algorithm and probability analysis.

    PubMed

    Yang, Tsung-Ming; Fan, Shu-Kai; Fan, Chihhao; Hsu, Nien-Sheng

    2014-08-01

    The purpose of this study is to establish a turbidity forecasting model as well as an early-warning system for turbidity management using rainfall records as the input variables. The Taipei Water Source Domain was employed as the study area, and ANOVA analysis showed that the accumulative rainfall records of 1-day Ping-lin, 2-day Ping-lin, 2-day Fei-tsui, 2-day Shi-san-gu, 2-day Tai-pin and 2-day Tong-hou were the six most significant parameters for downstream turbidity development. The artificial neural network model was developed and proven capable of predicting the turbidity concentration in the investigated catchment downstream area. The observed and model-calculated turbidity data were applied to developing the turbidity early-warning system. Using a previously determined turbidity as the threshold, the rainfall criterion, above which the downstream turbidity would possibly exceed this respective threshold turbidity, for the investigated rain gauge stations was determined. An exemplary illustration demonstrated the effectiveness of the proposed turbidity early-warning system as a precautionary alarm of possible significant increase of downstream turbidity. This study is the first report of the establishment of the turbidity early-warning system. Hopefully, this system can be applied to source water turbidity forecasting during storm events and provide a useful reference for subsequent adjustment of drinking water treatment operation.

  2. Phytoplankton productivity in a turbid buoyant coastal plume

    NASA Astrophysics Data System (ADS)

    Schofield, Oscar; Moline, Mark; Cahill, Brownyn; Frazer, Thomas; Kahl, Alex; Oliver, Matthew; Reinfelder, John; Glenn, Scott; Chant, Robert

    2013-07-01

    The complex dynamics associated with coastal buoyant plumes make it difficult to document the interactions between light availability, phytoplankton carbon fixation, and biomass accumulation. Using real-time data, provided by satellites and high frequency radar, we adaptively sampled a low salinity parcel of water that was exported from the Hudson river estuary in April 2005. The water was characterized by high nutrients and high chlorophyll concentrations. The majority of the low salinity water was re-circulated within a nearshore surface feature for 5 days during which nitrate concentrations dropped 7-fold, the maximum quantum yield for photosynthesis dropped 10-fold, and primary productivity rates decreased 5-fold. Associated with the decline in nitrate was an increase in phytoplankton biomass. The phytoplankton combined with the Colored Dissolved Organic Matter (CDOM) and non-algal particles attenuated the light so the 1% light level ranged between 3 and 10m depending on the age of the plume water. As the plume was 10-15m thick, the majority of the phytoplankton were light-limited. Vertical mixing within the plume was high as indicated by the dispersion of injected of rhodamine dye. The mixing within the buoyant plume was more rapid than phytoplankton photoacclimation processes. Mixing rates within the plume was the critical factor determining overall productivity rates within the turbid plume.

  3. Turbidity-based methods for continuous estimates of suspended sediment, particulate carbon, phosphorus and nitrogen fluxes

    NASA Astrophysics Data System (ADS)

    Jomaa, Seifeddine; Alsuliman, Malek; Rode, Michael

    2015-04-01

    A good evaluation of surface water pollution is mainly limited by the monitoring strategy and sampling frequencies. Carbon and nutrient monitoring at finer time intervals is still very difficult and expensive. Therefore, establishing relationships between grab sampling and continuous commonly available data can be considered as a favorable solution to turn this problem. The aim of this study was to develop a method to continuously estimate instream sediment, carbon, nitrogen and phosphorus concentrations based on high resolution measurement of turbidity, discharge, electrical conductivity and oxygen concentration. To achieve our gaols, high frequency data (30 min interval) were generated during 3 years at the UFZ- TERENO platform Bode (Terrestrial Environmental Observatories). Samples were analysed for suspended sediment concentration (SSC), particulate organic carbon (POC), total organic carbon (TOC), particulate nitrogen (PN) and particulate phosphorus (PP) using simple and multiple linear regression models. For this study, measurements from six sub-catchments with different geographical characteristics were considered. The available data sets were divided into two years (2010-2012) calibration and one year (2012-2013) validation periods. Results revealed that the turbidity was the most predictor variable in all models, particularly for suspended sediment concentrations. For all gauging stations, the SSC could be explained using simple linear regression model by the turbidity with a lowest correlation coefficient of 0.93. The non-uniqueness of the simple linear equation obtained between the stations reflected the sensitivity of the turbidity signal to the differences in land use and agriculture management between the sub-catchments. Best predictions of POC, TOC, PP and PN were achieved when multiple linear regression models were used including discharge, electrical conductivity and oxygen concentrations as predictor variables in addition to turbidity (lowest

  4. Salinity and turbidity distributions in the Brisbane River estuary, Australia

    NASA Astrophysics Data System (ADS)

    Yu, Yingying; Zhang, Hong; Lemckert, Charles

    2014-11-01

    The Brisbane River estuary (BRE) in Australia not only plays a vital role in ecosystem health, but is also of importance for people who live nearby. Comprehensive investigations, both in the short- and long-term, into the salinity and turbidity distributions in the BRE were conducted. Firstly, the analysis of numerical results revealed that the longitudinal salinity varied at approximately 0.45 and 0.61 psu/h during neap and spring tides, respectively. The turbidity stayed at a higher level and was less impacted by tide in the upper estuary, however, the water cleared up while the tide changed from flood to ebb in the mid and lower estuary. The second investigation into the seasonal variations of salinity and turbidity in the BRE was conducted, using ten-year field measurement data. A fourth-order polynomial equation was proposed, describing the longitudinal variation in salinity dilution changes as the upstream distance in the BRE during the wet and dry seasons. From the observation, the mid and upper estuaries were vertically well-mixed during both seasons, but the lower BRE was stratified, particularly during the wet season. The estuary turbidity maximum (ETM) zone was about 10 km longer during the wet season than the dry season. Particular emphasis was given to the third investigation into the use of satellite remote sensing techniques for estimation of the turbidity level in the BRE. A linear relationship between satellite observed water reflectance and surface turbidity level in the BRE was validated with an R2 of 0.75. The application of satellite-observed water reflectance therefore provided a practical solution for estimating surface turbidity levels of estuarine rivers not only under normal weather conditions, but also during flood events. The results acquired from this study are valuable for further hydrological research in the BRE and particularly prominent for immediate assessment of flood impacts.

  5. Climate-change refugia: shading reef corals by turbidity.

    PubMed

    Cacciapaglia, Chris; van Woesik, Robert

    2016-03-01

    Coral reefs have recently experienced an unprecedented decline as the world's oceans continue to warm. Yet global climate models reveal a heterogeneously warming ocean, which has initiated a search for refuges, where corals may survive in the near future. We hypothesized that some turbid nearshore environments may act as climate-change refuges, shading corals from the harmful interaction between high sea-surface temperatures and high irradiance. We took a hierarchical Bayesian approach to determine the expected distribution of 12 coral species in the Indian and Pacific Oceans, between the latitudes 37°N and 37°S, under representative concentration pathway 8.5 (W m(-2) ) by 2100. The turbid nearshore refuges identified in this study were located between latitudes 20-30°N and 15-25°S, where there was a strong coupling between turbidity and tidal fluctuations. Our model predicts that turbidity will mitigate high temperature bleaching for 9% of shallow reef habitat (to 30 m depth) - habitat that was previously considered inhospitable under ocean warming. Our model also predicted that turbidity will protect some coral species more than others from climate-change-associated thermal stress. We also identified locations where consistently high turbidity will likely reduce irradiance to <250 μmol m(-2)  s(-1) , and predict that 16% of reef-coral habitat ≤30 m will preclude coral growth and reef development. Thus, protecting the turbid nearshore refuges identified in this study, particularly in the northwestern Hawaiian Islands, the northern Philippines, the Ryukyu Islands (Japan), eastern Vietnam, western and eastern Australia, New Caledonia, the northern Red Sea, and the Arabian Gulf, should become part of a judicious global strategy for reef-coral persistence under climate change.

  6. Angular domain spectroscopic imaging of turbid media using silicon micromachined microchannel arrays

    NASA Astrophysics Data System (ADS)

    Vasefi, Fartash; Ng, Eldon; Najiminaini, Mohamadreza; Albert, Genevieve; Kaminska, Bozena; Chapman, Glenn H.; Carson, Jeffrey J. L.

    2010-02-01

    We experimentally characterized a novel Angular Domain Spectroscopic Imaging (ADSI) technique for the detection and characterization of optical contrast abnormalities in turbid media. The new imaging system employs silicon micromachined angular filtering methodology, which has high angular selectivity for photons exiting the turbid medium. The angular filter method offers efficient scattered light suppression at moderate levels of scattering (i.e. up to 6 reduced mean free paths). An ADSI system was constructed from a broadband light source, an Angular Filter Array (AFA), and an imaging spectrometer. The free-space collimated broadband light source was used to trans-illuminate a turbid sample over a wide range of wavelengths in the near infrared region of the spectrum. The imaging spectrometer decomposed the output of the AFA into hyperspectral images representative of spatial location and wavelength. It collected and angularly filtered a line image from the object onto the CCD camera with the spatial information displayed along one axis and wavelength information along the other. The ADSI system performance was evaluated on tissue-mimicking phantoms as well as fresh chicken breast tissue. Collected images with the ADSI displayed differences in image contrast between different tissue types.

  7. Rheological characterization and turbidity of riboflavin-photosensitized changes in alginate/GDL systems.

    PubMed

    Baldursdóttir, Stefanía G; Kjøniksen, Anna-Lena

    2005-04-01

    Riboflavin (RF) in combination with light, in the wavelength range of 310-800 nm, is used to induce degradation of alginic acid gels. Light irradiation of alginate solutions in the presence of RF under aerobic conditions causes scission of the polymer chains. In the development process of a new drug delivery system, RF photosensitized degradation of alginic acid gels is studied by monitoring changes in the turbidity and rheological parameters of alginate/glucono-delta-lactone (GDL) systems with different concentrations of GDL. Addition of GDL induces gel formation of the samples by gradually lowering the pH-value of the system. The turbidity is measured and the cloud point determined. The turbidity starts to increase after shorter times with enhanced concentration of GDL. Enhanced viscoelasticity is detected with increasing GDL concentration in the post-gel regime, but small differences are detected at the gel point. The incipient gel is 'soft' and has an open structure independent on the GDL concentration. In the post-gel regime solid-like behavior is observed, this is more distinct for the systems with high GDL concentrations. The effect of photosensitized RF on alginate/GDL systems decreases with increasing amount of GDL in the system. The same trend is detected whether the systems are irradiated in the pre-gel or in the post-gel regime.

  8. In situ toxicity evaluations of turbidity and photoinduction of polycyclic aromatic hydrocarbons

    SciTech Connect

    Ireland, D.S.; Burton, G.A. Jr; Hess, G.G.

    1996-04-01

    Polycyclic aromatic hydrocarbons (PAHs) are prevalent pollutants in the aquatic environment that can cause a wide range of toxic effects. Earlier studies have shown that toxicity of PAHs can be enhanced by ultraviolet (UV) radiation. In situ and laboratory exposures with Ceriodaphnia dubia were used to evaluate photoinduced toxicity of PAHs in wet-weather runoff and in turbid conditions. Exposure to UV increased the toxicity of PAH-contaminated sediment to C. dubia. Toxicity was removed when UV wavelengths did not penetrate the water column to the exposed organisms. A significant correlation was observed between in situ C. dubia survival and turbidity when organisms were exposed to sunlight. Stormwater runoff samples exhibited an increase in chronic toxicity (reproduction) to C. dubia when exposed to UV wavelengths as compared to C. dubia not exposed to UV wavelengths. Toxicity was reduced significantly in the presence of UV radiation when the organic fraction of stormwater runoff was removed. The PAHs are bound to the sediment and resuspended into the water column once the sediment is disturbed (e.g., during a storm). The in situ and laboratory results showed that photoinduced toxicity occurred frequently during low flow conditions and wet weather runoff and was reduced in turbid conditions.

  9. Estimation of suspended sediment concentration from turbidity measurements using artificial neural networks.

    PubMed

    Bayram, Adem; Kankal, Murat; Onsoy, Hizir

    2012-07-01

    Suspended sediment concentration (SSC) is generally determined from the direct measurement of sediment concentration of river or from sediment transport equations. Direct measurement is very costly and cannot be conducted for all river gauge stations. Therefore, correct estimation of suspended sediment amount carried by a river is very important in terms of water pollution, channel navigability, reservoir filling, fish habitat, river aesthetics and scientific interests. This study investigates the feasibility of using turbidity as a surrogate for SSC as in situ turbidity meters are being increasingly used to generate continuous records of SSC in rivers. For this reason, regression analysis (RA) and artificial neural networks (ANNs) were employed to estimate SSC based on in situ turbidity measurements. The SSC was firstly experimentally determined for the surface water samples collected from the six monitoring stations along the main branch of the stream Harsit, Eastern Black Sea Basin, Turkey. There were 144 data for each variable obtained on a fortnightly basis during March 2009 and February 2010. In the ANN method, the used data for training, testing and validation sets are 108, 24 and 12 of total 144 data, respectively. As the results of analyses, the smallest mean absolute error (MAE) and root mean square error (RMSE) values for validation set were obtained from the ANN method with 11.40 and 17.87, respectively. However these were 19.12 and 25.09 for RA. It was concluded that turbidity could be a surrogate for SSC in the streams, and the ANNs method used for the estimation of SSC provided acceptable results.

  10. A Comparison of Turbidity-Based and Streamflow-Based Estimates of Suspended-Sediment Concentrations in Three Chesapeake Bay Tributaries

    USGS Publications Warehouse

    Jastram, John D.; Moyer, Douglas; Hyer, Kenneth

    2009-01-01

    Fluvial transport of sediment into the Chesapeake Bay estuary is a persistent water-quality issue with major implications for the overall health of the bay ecosystem. Accurately and precisely estimating the suspended-sediment concentrations (SSC) and loads that are delivered to the bay, however, remains challenging. Although manual sampling of SSC produces an accurate series of point-in-time measurements, robust extrapolation to unmeasured periods (especially highflow periods) has proven to be difficult. Sediment concentrations typically have been estimated using regression relations between individual SSC values and associated streamflow values; however, suspended-sediment transport during storm events is extremely variable, and it is often difficult to relate a unique SSC to a given streamflow. With this limitation for estimating SSC, innovative approaches for generating detailed records of suspended-sediment transport are needed. One effective method for improved suspended-sediment determination involves the continuous monitoring of turbidity as a surrogate for SSC. Turbidity measurements are theoretically well correlated to SSC because turbidity represents a measure of water clarity that is directly influenced by suspended sediments; thus, turbidity-based estimation models typically are effective tools for generating SSC data. The U.S. Geological Survey, in cooperation with the U.S. Environmental Protection Agency Chesapeake Bay Program and Virginia Department of Environmental Quality, initiated continuous turbidity monitoring on three major tributaries of the bay - the James, Rappahannock, and North Fork Shenandoah Rivers - to evaluate the use of turbidity as a sediment surrogate in rivers that deliver sediment to the bay. Results of this surrogate approach were compared to the traditionally applied streamflow-based approach for estimating SSC. Additionally, evaluation and comparison of these two approaches were conducted for nutrient estimations. Results

  11. Normalized velocity profiles of field-measured turbidity currents

    USGS Publications Warehouse

    Xu, Jingping

    2010-01-01

    Multiple turbidity currents were recorded in two submarine canyons with maximum speed as high as 280 cm/s. For each individual turbidity current measured at a fixed station, its depth-averaged velocity typically decreased over time while its thickness increased. Some turbidity currents gained in speed as they traveled downcanyon, suggesting a possible self-accelerating process. The measured velocity profiles, first in this high resolution, allowed normalizations with various schemes. Empirical functions, obtained from laboratory experiments whose spatial and time scales are two to three orders of magnitude smaller, were found to represent the field data fairly well. The best similarity collapse of the velocity profiles was achieved when the streamwise velocity and the elevation were normalized respectively by the depth-averaged velocity and the turbidity current thickness. This normalization scheme can be generalized to an empirical function Y = exp(–αXβ) for the jet region above the velocity maximum. Confirming theoretical arguments and laboratory results of other studies, the field turbidity currents are Froude-supercritical.

  12. Temporal analysis of remotely sensed turbidity in a coastal archipelago

    NASA Astrophysics Data System (ADS)

    Suominen, Tapio; Tolvanen, Harri

    2016-07-01

    A topographically fragmental archipelago with dynamic waters set the preconditions for assessing coherent remotely sensed information. We generated a turbidity dataset for an archipelago coast in the Baltic Sea from MERIS data (FSG L1b), using CoastColour L1P, L2R and L2W processors. We excluded land and mixed pixels by masking the imagery with accurate (1:10 000) shoreline data. Using temporal linear averaging (TLA), we produced satellite-imagery datasets applicable to temporal composites for the summer seasons of three years. The turbidity assessments and temporally averaged data were compared to in situ observations obtained with coastal monitoring programs. The ability of TLA to estimate missing pixel values was further assessed by cross-validation with the leave-one-out method. The correspondence between L2W turbidity and in situ observations was good (r = 0.89), and even after applying TLA the correspondence remained acceptable (r = 0.78). The datasets revealed spatially divergent temporal water characteristics, which may be relevant to the management, design of monitoring and habitat models. Monitoring observations may be spatially biased if the temporal succession of water properties is not taken into account in coastal areas with anisotropic dispersion of waters and asynchronous annual cycles. Accordingly, areas of varying turbidity may offer a different habitat for aquatic biota than areas of static turbidity, even though they may appear similar if water properties are measured for short annual periods.

  13. Experimentally measured MTF's associated with imaging through turbid water

    NASA Astrophysics Data System (ADS)

    Witherspoon, N.; Strand, M.; Holloway, J., Jr.; Price, B.; Brown, D.

    1988-01-01

    One factor which affects the ability to image an underwater object from the atmosphere is water turbidity. The performance of an imaging system is often expressed by the limiting resolution which is determined from the contrast transfer function (CTF). The image quality is usually expressed in terms of the modulation transfer function (MTF). This paper presents the results from carefully controlled laboratory experiments to determine the CTFs and the MTFs of a turbid water medium for Jackson turbidity units (JTUs) ranging from 0 to 24. MTFs are generated from a narrow strip target and CTFs are generated from standard resolution bar targets. MTF results are compared with earlier work and CTFs calculated from MTFs are compared with measured CTFs.

  14. Measurement of "turbidity" and related characteristics of natural waters

    USGS Publications Warehouse

    Pickering, R.J.

    1976-01-01

    The U.S. Geological Survey, Water Resources Division has adopted the following principles to be used in selecting methods for the measurement of light transmitting characteristics of natural waters: (1) standard instruments and methods are to be adopted to measure and report in optical units, avoiding ' turbidity ' as a quantitative measure; (2) reporting of ' turbidity ' in JTU 's, Hellige units, severity, or NTU 's will be phased out; (3) the basis for estimations of sediment concentrations based on light measurements must be documented adequately; and (4) use of transparency measurement by Secchi disk is not changed, although light transmittance may prove to be more precise means of obtaining the same information. A schedule has been established to implement new methods beginning October 1, 1976, and with the transition to be completed at all stations by October 1, 1977. Provisions are provided to meet requirements of cooperators who have legal requirements for ' turbidity ' data. (Woodard-USGS)

  15. A feasibility study for a remote laser water turbidity meter

    NASA Technical Reports Server (NTRS)

    Hickman, G. D.; Ghovanlou, A. H.; Friedman, E. J.; Gault, C. S.; Hogg, J. E.

    1974-01-01

    A technique to remotely determine the attenuation coefficient (alpha) of the water was investigated. The backscatter energy (theta = 180 deg) of a pulse laser (lambda = 440 - 660 nm) was found directly related to the water turbidity. The greatest sensitivity was found to exist at 440 nm. For waters whose turbidity was adjusted using Chesapeake Bay sediment, the sensitivity in determining alpha at 440 nm was found to be approximately 5 - 10%. A correlation was also found to exist between the water depth (time) at which the peak backscatter occurs and alpha.

  16. Light Backscattering Polarization Patterns from Turbid Media: Theory and Experiment

    NASA Astrophysics Data System (ADS)

    Rakovic, Milun J.; Kattawar, George W.; Mehrubeoglu, Mehrube; Cameron, Brent D.; Wang, Lihong V.; Rastegar, Sohi; Coté, Gerard L.

    1999-05-01

    We present both experimental measurements and Monte-Carlo-based simulations of the diffusely backscattered intensity patterns that arise from illuminating a turbid medium with a polarized laser beam. It is rigorously shown that, because of axial symmetry of the system, only seven elements of the effective backscattering Mueller matrix are independent. A new numerical method that allows simultaneous calculation of all 16 elements of the two-dimensional Mueller matrix is used. To validate our method we compared calculations to measurements from a turbid medium that consisted of polystyrene spheres of different sizes and concentrations in deionized water. The experimental and numerical results are in excellent agreement.

  17. Light backscattering polarization patterns from turbid media: theory and experiment.

    PubMed

    Raković, M J; Kattawar, G W; Mehrubeoğlu, M B; Cameron, B D; Wang, L V; Rastegar, S; Coté, G L

    1999-05-20

    We present both experimental measurements and Monte-Carlo-based simulations of the diffusely backscattered intensity patterns that arise from illuminating a turbid medium with a polarized laser beam. It is rigorously shown that, because of axial symmetry of the system, only seven elements of the effective backscattering Mueller matrix are independent. A new numerical method that allows simultaneous calculation of all 16 elements of the two-dimensional Mueller matrix is used. To validate our method we compared calculations to measurements from a turbid medium that consisted of polystyrene spheres of different sizes and concentrations in deionized water. The experimental and numerical results are in excellent agreement.

  18. Fluorescence correlation spectroscopy: Ultrasensitive detection in clear and turbid media

    NASA Astrophysics Data System (ADS)

    Tahari, Abdel Kader

    In this work, I describe the development of a simple, inexpensive, and powerful alternative technique to detect and analyze, without enrichment, extremely low concentrations of cells, bacteria, viruses, and protein aggregates in turbid fluids for clinical and biotechnological applications. The anticipated applications of this technique are many. They range from the determination of the somatic cell count in milk for the dairy industry, to the enumeration and characterization of microorganisms in environmental microbiology and the food industry, and to the fast and ultrasensitive detection of protein aggregates for the diagnosis of Alzheimer's and other neurodegenerative diseases in clinical medicine. A prototype instrument has been built and allowed the detection and quantification of particles down to a few per milliliter in short scanning times. It consists of a small microscope that has a horizontal geometry and a mechanical instrument that holds a cylindrical cuvette (1 cm in diameter) with two motors that provide a rotational and a slower vertical inversion motions. The illumination focus is centered about 200 mum from the wall of the cuvette inside the sample. The total volume that is explored is large (˜1ml/min for bright particles). The data is analyzed with a correlation filter program based on particle passage pattern recognition. I will also describe further work on improving the sensitivity of the technique, expanding it for multiple-species discrimination and enumeration, and testing the prototype device in actual clinical and biotechnological applications. The main clinical application of this project seeks to establish conditions and use this new technique to quantify and size-analyze oligomeric complexes of the Alzheimer's disease beta-peptide in cerebrospinal fluid and other body fluids as a molecular biomarker for persons at risk of Alzheimer's disease dementia. The technology could potentially be extended to the diagnosis and therapeutic

  19. Angular domain optical projection tomography in turbid media

    NASA Astrophysics Data System (ADS)

    Vasefi, Fartash; Kaminska, Bozena; Jordan, Kevin; Chapman, Glenn H.; Carson, Jeffrey J. L.

    2009-02-01

    Most high-resolution optical tomography techniques employ coherence domain or time domain methodologies to capture non-scattered photons in turbid media. Angular Domain Optical Projection Tomography (ADOPT) uses an angular filter array (AFA) to observe photons that propagate through a specimen with small angular deviation. We constructed an ADOPT system consisting of an AFA micro-machined silicon micro-tunnel array with each micro-tunnel 60 μm wide, 60 μm high, 10 mm long, and separated by 5 μm thick walls. The range of acceptance angles was 0° to 0.5°. The system also included an 808 nm CW diode laser, beam shaping optics, a sample cuvette, a Keplerian lens system, and a CMOS camera. Testing was performed with a target consisting of two graphite rods (0.9 mm diameter) suspended in the cuvette by a rotation stage. The target was placed in a manner that the line of laser light was perpendicular to the long axis of the rods. A multitude of projections were collected at increments of 1.8° and compiled into a sinogram. A transverse image was reconstructed from the sinogram using filtered backprojection. The submillimeter targets embedded in the 2 cm thick scattering medium (reduced scattering coefficient <= 2.4 cm-1) were discernable in both the sinograms and the reconstructed images. The results suggest that ADOPT may be a useful technique for tomographic imaging of thick biological specimens (i.e. up to 8 mm across).

  20. Utilizing Turbidity and Measurements of Suspended Sediment Concentrations to Better Understand Sediment Transport within Urban Streams

    NASA Astrophysics Data System (ADS)

    Elkins, T. M.; Napieralski, J. A.

    2009-12-01

    The Rouge River watershed in Southeast Michigan is an urban watershed, which has been exposed to more than 100 years of anthropogenic activities related to industrialization and urbanization. This urbanization has degraded water quality by increasing erosion and altering the transport mechanism and chemistry of bed and suspended sediments. This study aims to explore the relationship between development within the Lower Rouge watershed and watershed hydrology through an examination of USGS discharge data, stream water quality and suspended sediment loads during storm and base flow. Two YSI dataloggers are used to continuously measure water quality parameters during baseflow and storm events (varying hydrologic conditions), including: turbidity, dissolved oxygen, conductivity, salinity, total dissolved solids, and temperature. Depth-integrated sediment samples are collected and analyzed for sediment concentration using Imhoff cones and filtration methods. Correlations between discharge weighted continuous turbidity measurements and discharge weighted suspended sediment samples are used to estimate sediment loads; essentially, turbidity readings and measured sediment concentrations form a near-linear relationship. In addition, sediment samples are analyzed for inorganic heavy metal contaminants common to Southeast Michigan to characterize both suspended sediments and sediments frequently deposited on adjacent floodplains. These metals (i.e. Lead, Copper, Chromium, Nickle) are commonly known as the “Michigan Metals” and represent indicator species of mobilized and deposited contaminants associated with urbanization and industrialization. The results will provide a baseline for better understanding the transport and fate of contaminated sediments within the Rouge watershed, as well as guide ongoing development and management practices along the Rouge River.

  1. Effect of sand bed depth and media age on Escherichia coli and turbidity removal in biosand filters.

    PubMed

    Napotnik, Julie A; Baker, Derek; Jellison, Kristen L

    2017-02-17

    The main objective of this study was to build several full-scale biosand filters (BSFs) and assess the long-term (9 month) efficacy for particulate and Escherichia coli removal under simulated real-world usage. Four replicates of three different filter designs were built: the traditional concrete BSF, and two scaled-down versions that use a 5-gal or 2-gal bucket, respectively, as the casing material. The smaller sand bed depths in the bucket-sized filters did not impact filter performance with respect to (i) turbidity and E. coli removal or (ii) effluent levels of turbidity and E. coli. All filters produced effluents with a mean turbidity of <0.6 NTU. In addition, 78%, 74%, and 72% of effluent samples for the concrete, 5-gal, and 2-gal filters, respectively, had E. coli concentrations <1 CFU/100 mL. The bucket-sized filters were found to be a potential alternative to the concrete BSFs for the removal of E. coli and turbidity from drinking water. Since smaller BSFs must be filled more frequently than larger BSFs to produce comparable water volumes, the effect of shorter pause periods on BSF performance should be investigated.

  2. Water quality determination by photographic analysis. [optical density and water turbidity

    NASA Technical Reports Server (NTRS)

    Klooster, S. A.; Scherz, J. P.

    1973-01-01

    Aerial reconnaissance techniques to extract water quality parameters from aerial photos are reported. The turbidity can be correlated with total suspended solids if the constituent parts of the effluent remain the same and the volumetric flow remains relatively constant. A monochromator is used for the selection of the bandwidths containing the most information. White reflectance panels are used to locate sampling points and eliminate inherent energy changes from lens flare, radial lens fall-off, and changing subject illumination. Misleading information resulting from bottom effects is avoided by the use of Secchi disc readings and proper choice of wavelength for analyzing the photos.

  3. Remote estimation of the diffuse attenuation coefficient in a moderately turbid estuary

    USGS Publications Warehouse

    Stumpf, R.P.; Pennock, J.R.

    1991-01-01

    Solutions of the radiative transfer equation are used to derive relationships of water reflectance to the diffuse attenuation coefficient (K) in moderately turbid water (K > 0.5 m-1). Data sets collected from the NOAA AVHRR and in situ observations from five different dates confirm the appropriateness of these relationships, in particular the logistic equation. Values of K calculated from the reflectance data agree to within 60% of the observed values, although the reflectance derived using a more comprehensive aerosol correction is sensitive to chlorophyll concentrations greater than 50 ??g L-1. Agreement between in situ and remote observations improves as the time interval between samples is narrowed. ?? 1991.

  4. Evolution of particle size in turbid discharge plumes

    DTIC Science & Technology

    2016-06-07

    Evolution of particle size in turbid discharge plumes Paul S. Hill Department of Oceanography Dalhousie University Halifax, Nova Scotia, CANADA B3H...ES) Dalhousie University,Department of Oceanography,Halifax, Nova Scotia B3H 4J1, Canada, 8. PERFORMING ORGANIZATION REPORT NUMBER 9. SPONSORING

  5. 40 CFR 141.13 - Maximum contaminant levels for turbidity.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... turbidity. 141.13 Section 141.13 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) WATER PROGRAMS (CONTINUED) NATIONAL PRIMARY DRINKING WATER REGULATIONS Maximum Contaminant Levels § 141.13... both community water systems and non-community water systems using surface water sources in whole or...

  6. 40 CFR 141.13 - Maximum contaminant levels for turbidity.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... turbidity. 141.13 Section 141.13 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) WATER PROGRAMS (CONTINUED) NATIONAL PRIMARY DRINKING WATER REGULATIONS Maximum Contaminant Levels § 141.13... both community water systems and non-community water systems using surface water sources in whole or...

  7. Laser measure of sea salinity, temperature and turbidity in depth

    NASA Technical Reports Server (NTRS)

    Hirschberg, J. G.; Wouters, A. W.; Byrne, J. D.

    1974-01-01

    A method is described in which a pulsed laser is used to probe the sea. Backscattered light is analyzed in time, intensity and wavelength. Tyndall, Raman and Brillouin scattering are used to obtain the backscatter turbidity, sound velocity, salinity, and the temperature as a function of depth.

  8. 40 CFR 230.21 - Suspended particulates/turbidity.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 26 2013-07-01 2013-07-01 false Suspended particulates/turbidity. 230.21 Section 230.21 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) OCEAN DUMPING... time. These new levels may reduce light penetration and lower the rate of photosynthesis and...

  9. 40 CFR 230.21 - Suspended particulates/turbidity.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 25 2014-07-01 2014-07-01 false Suspended particulates/turbidity. 230.21 Section 230.21 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) OCEAN DUMPING... time. These new levels may reduce light penetration and lower the rate of photosynthesis and...

  10. Operational monitoring of turbidity in rivers: how satellites can contribute

    NASA Astrophysics Data System (ADS)

    Hucke, Dorothee; Hillebrand, Gudrun; Winterscheid, Axel; Kranz, Susanne; Baschek, Björn

    2016-10-01

    The applications of remote sensing in hydrology are diverse and offer significant benefits for water monitoring. Up to now, operational river monitoring and sediment management in Germany mainly rely on in-situ measurements and on results obtained from numerical modelling. Remote sensing by satellites has a great potential to supplement existing data with two-dimensional information on near-surface turbidity distributions at greater spatial scales than in-situ measurements can offer. Within the project WasMon-CT (WaterMonitoring-Chlorophyll/Turbidity), the Federal Institute of Hydrology (BfG) aims at the implementation of an operational monitoring of turbidity distributions based on satellite images (esp. Sentinel-2, Landsat7 and 8). Initially, selected federal inland and estuarine waterways will be addressed: Rhine, Elbe, Ems, Weser. WasMon-CT is funded within the German Copernicus activities. Within the project, a database of atmospherically corrected, geo-referenced turbidity data will be assembled. The collected corresponding meta-data will include aspects of satellite data as well as hydrological data, e.g. cloud cover and river run-off. Based on this catalogue of spatially linked meta-data, the satellite data will be selected by e.g. cloud cover or run-off. The permanently updated database will include past as well as recent satellite images. It is designed with a long-term perspective to optimize the existing in-situ measurement network, which will serve partly for calibration and partly as validation data set. The aim is to extend, but not to substitute, the existing frequent point measurements with spatially extensive, satellite-derived data from the near surface part of the water column. Here, turbidity is used as proxy for corresponding suspended sediment concentrations. For this, the relationship between turbidity and suspended sediment concentrations will be investigated. Products as e.g. longitudinal profiles or virtual measurement stations will be

  11. USING TURBIDITY DATA TO PREDICT SUSPENDED SEDIMENT CONCENTRATIONS: POSSIBILITIES, LIMITATIONS, AND PITFALLS

    EPA Science Inventory

    This talk will look at the relationships between turbidity and suspended sediment concentrations in a variety of geographic areas, geomorphic river types, and river sizes; and attempt to give guidance on using existing turbidity data to predict suspended sediment concentrations.

  12. Do larval fishes exhibit diel drift patterns in a large, turbid river?

    USGS Publications Warehouse

    Reeves, K.S.; Galat, D.L.

    2010-01-01

    Previous research suggested larval fishes do not exhibit a diel drift cycle in turbid rivers (transparency <30 cm). We evaluated this hypothesis in the turbid, lower Missouri River, Missouri. We also reviewed diel patterns of larval drift over a range of transparencies in rivers worldwide. Larval fishes were collected from the Missouri River primary channel every 4 h per 24-h period during spring-summer 2002. Water transparency was measured during this period and summarized for previous years. Diel drift patterns were analyzed at the assemblage level and lower taxonomic levels for abundant groups. Day and night larval fish catch-per-unit-effort (CPUE) was compared for the entire May through August sampling period and spring (May - June) and summer (July - August) seasons separately. There were no significant differences between day and night CPUE at the assemblage level for the entire sampling period or for the spring and summer seasons. However, Hiodon alosoides, Carpiodes/Ictiobus spp. and Macrhybopsis spp. exhibited a diel cycle of abundance within the drift. This pattern was evident although mean Secchi depth (transparency) ranged from 4 to 25 cm during the study and was <30 cm from May through August over the previous nine years. Larval diel drift studies from 48 rivers excluding the Missouri River indicated the primary drift period for larval fishes was at night in 38 rivers and during the day for five, with the remaining rivers showing no pattern. Water transparency was reported for 10 rivers with six being <30 cm or 'low'. Two of these six turbid rivers exhibited significant diel drift patterns. The effect of water transparency on diel drift of larval fishes appears taxa-specific and patterns of abundant taxa could mask patterns of rare taxa when analyzed only at the assemblage level. ?? 2010 Blackwell Verlag, Berlin.

  13. Optical rotation and linear and circular depolarization rates in diffusively scattered light from chiral, racemic, and achiral turbid media.

    PubMed

    Hadley, Kevin C; Vitkin, I Alex

    2002-07-01

    The polarization properties of light scattered in a lateral direction from turbid media were studied. Polarization modulation and synchronous detection were used to measure, and Mueller calculus to model and derive, the degrees of surviving linear and circular polarization and the optical rotation induced by turbid samples. Polystyrene microspheres were used as scatterers in water solutions containing dissolved chiral, racemic, and achiral molecules. The preservation of circular polarization was found to exceed the linear polarization preservation for all samples examined. The optical rotation induced increased with the chiral molecule concentration only, whereas both linear and circular polarizations increased with an increase in the concentrations of chiral, racemic, and achiral molecules. This latter effect was shown to stem solely from the refractive index matching mechanism induced by the solute molecules, independent of their chiral nature.

  14. A turbidity current model for real world applications

    NASA Astrophysics Data System (ADS)

    Macías, Jorge; Castro, Manuel J.; Morales, Tomás

    2016-04-01

    Traditional turbidity current models suffer from several drawbacks. Among them not preserving freshwater mass, a missing pressure term, or not including terms related to deposition, erosion and entrainment in the momentum equation. In Morales et al.(2009) a new turbidity current model was proposed trying to overcome all these drawbacks. This model takes into account the interaction between the turbidity current and the bottom, considering deposition and erosion effects as well as solid bedload transport of particles at the bed due to the current. Moreover, this model includes the effects of the deposition, erosion and water entrainment into the momentum equation,commonly neglected in this type of models and, finally, in the absence of water entrainment, freshwater mass in the turbidity current is preserved. Despite these improvements, the numerical results obtained by this model when applied to real river systems were not satisfactory due to the simple form of the friction term that was considered. In the present work we propose a different parameterization of this term, where bottom and interface fluid frictions are separately parameterized with more complex expressions. Moreover, the discretization of the deposition/erosion terms is now performed semi-implicitly which guarantees the positivity of the volumetric concentration of sediments in suspension and in the erodible sediment layer at the bed. The numerical simulations obtained with this new turbidity current model (component of HySEA numerical computing platform) greatly improve previous numerical results for simplified geometries as well as for real river systems. Acknowledgements: This research has been partially supported by the Junta de Andalucía research project TESELA (P11-RNM7069) and the Spanish Government Research project DAIFLUID (MTM2012-38383-C02-01) and Universidad de Málaga, Campus de Excelencia Andalucía TECH. References: T. Morales, M. Castro, C. Parés, and E. Fernández-Nieto (2009). On

  15. Glyphosate input modifies microbial community structure in clear and turbid freshwater systems.

    PubMed

    Pizarro, H; Vera, M S; Vinocur, A; Pérez, G; Ferraro, M; Menéndez Helman, R J; Dos Santos Afonso, M

    2016-03-01

    Since it was commercially introduced in 1974, glyphosate has been one of the most commonly used herbicides in agriculture worldwide, and there is growing concern about its adverse effects on the environment. Assuming that glyphosate may increase the organic turbidity of water bodies, we evaluated the effect of a single application of 2.4 ± 0.1 mg l(-1) of glyphosate (technical grade) on freshwater bacterioplankton and phytoplankton (pico, micro, and nanophytoplankton) and on the physical and chemical properties of the water. We used outdoor experimental mesocosms under clear and oligotrophic (phytoplanktonic chlorophyll a = 2.04 μg l(-1); turbidity = 2.0 NTU) and organic turbid and eutrophic (phytoplanktonic chlorophyll a = 50.3 μg l(-1); turbidity = 16.0 NTU) scenarios. Samplings were conducted at the beginning of the experiment and at 1, 8, 19, and 33 days after glyphosate addition. For both typologies, the herbicide affected the abiotic water properties (with a marked increase in total phosphorus), but it did not affect the structure of micro and nanophytoplankton. In clear waters, glyphosate treatment induced a trend toward higher bacteria and picoeukaryotes abundances, while there was a 2 to 2.5-fold increase in picocyanobacteria number. In turbid waters, without picoeukaryotes at the beginning of the experiment, glyphosate decreased bacteria abundance but increased the number of picocyanobacteria, suggesting a direct favorable effect. Moreover, our results show that the impact of the herbicide was observed in microorganisms from both oligo and eutrophic conditions, indicating that the impact would be independent of the trophic status of the water body.

  16. Effects of Turbidity on Fluridone Treatments for Curlyleaf Pondweed Control

    DTIC Science & Technology

    2008-03-01

    Manage. 41:113-118. Yaron-Marcovich, D., S. Nir, and Y. Chen. 2004. Fluridone adsorption-desorption on organo - clays . Applied Clay Sci. 24:167-175...Nichols 1994). These species usually have complex and deep root systems to withstand wind-driven waves that scour the lake bottom, suspending...caused by suspended organic matter, sediment, and other inorganic particles. Clays also may comprise a part of the suspended sediment found in turbid

  17. Simplified multiple scattering model for radiative transfer in turbid water

    NASA Technical Reports Server (NTRS)

    Ghovanlou, A. H.; Gupta, G. N.

    1978-01-01

    Quantitative analytical procedures for relating selected water quality parameters to the characteristics of the backscattered signals, measured by remote sensors, require the solution of the radiative transport equation in turbid media. Presented is an approximate closed form solution of this equation and based on this solution, the remote sensing of sediments is discussed. The results are compared with other standard closed form solutions such as quasi-single scattering approximations.

  18. Imaging in turbid media: a transmission detector gives 2-3 order of magnitude enhanced sensitivity compared to epi-detection schemes.

    PubMed

    Dvornikov, Alexander; Gratton, Enrico

    2016-09-01

    Imaging depth in turbid media by two-photon fluorescence microscopy depends on the ability of the optical system to detect weak fluorescence signals. We have shown that use of a wide area detector in transmission geometry allows increasing imaging depth in turbid media due to efficient photon collection. Compared to the conventional epi-detection scheme used in most commercial microscopes, the transmission detector was found to be 2-3 orders of magnitude more sensitive when used for in depth imaging in scattering samples simulating brain optical properties.

  19. Imaging in turbid media: a transmission detector gives 2-3 order of magnitude enhanced sensitivity compared to epi-detection schemes

    PubMed Central

    Dvornikov, Alexander; Gratton, Enrico

    2016-01-01

    Imaging depth in turbid media by two-photon fluorescence microscopy depends on the ability of the optical system to detect weak fluorescence signals. We have shown that use of a wide area detector in transmission geometry allows increasing imaging depth in turbid media due to efficient photon collection. Compared to the conventional epi-detection scheme used in most commercial microscopes, the transmission detector was found to be 2–3 orders of magnitude more sensitive when used for in depth imaging in scattering samples simulating brain optical properties. PMID:27699135

  20. Remote measurement of water color in coastal waters. [spectral radiance data used to obtain quantitative values for chlorophyll and turbidity

    NASA Technical Reports Server (NTRS)

    Weldon, J. W.

    1973-01-01

    An investigation was conducted to develop procedure to obtain quantitative values for chlorophyll and turbidity in coastal waters by observing the changes in spectral radiance of the backscattered spectrum. The technique under consideration consists of Examining Exotech model 20-D spectral radiometer data and determining which radiance ratios best correlated with chlorophyll and turbidity measurements as obtained from analyses of water samples and sechi visibility readings. Preliminary results indicate that there is a correlation between backscattered light and chlorophyll concentration and secchi visibility. The tests were conducted with the spectrometer mounted in a light aircraft over the Mississippi Sound at altitudes of 2.5K, 2.8K and 10K feet.

  1. Note: refractive index sensing of turbid media by differentiation of the reflectance profile: does error-correction work?

    PubMed

    Goyal, K G; Dong, M L; Kane, D G; Makkar, S S; Worth, B W; Bali, L M; Bali, S

    2012-08-01

    A widely used method for determining refractive index postulates that the derivative of the angular profile for light reflected from the sample is maximum at the critical angle for total internal reflection (TIR). It is well-known that in turbid media this "differentiation method" yields errors in refractive index. Unexplained anomalies in previous error-calculations are eliminated if one uses a recent model of TIR which departs from traditional Fresnel theory. However we find that, in practical situations, the refractive index obtained by differentiation even after error-correction is significantly different from the best estimate for the refractive index obtained by curve-fitting the reflectance data. Thus the differentiation method lacks scientific validity in turbid media.

  2. Indirect determination of broadband turbidity coefficients over Egypt

    NASA Astrophysics Data System (ADS)

    El-Metwally, Mossad

    2013-01-01

    Long-term data from diffuse and global irradiances were used to calculate direct beam irradiance which was used to determine three atmospheric turbidity coefficients (Linke T L , Ångström β and Unsworth-Monteith δ a ) at seven sites in Egypt in the period from 1981 to 2000. Seven study sites (Barrani, Matruh, Arish, Cairo, Asyut, Aswan and Kharga) have been divided into three categories: Mediterranean climate (MC), desert Nile climate (DNC) and urban climate (UC, Cairo). The indirect method (i.e., global irradiance minus diffuse irradiance) used here allows to estimate the turbidity coefficients with an RMSE% ≤20 % (for β, δ a and T L ) and ~30 % (for β) if compared with those estimated by direct beam irradiance and sunphotometeric data, respectively. Monthly averages of T L , β and δ a show seasonal variations with mainly maxima in spring at all stations, due to Khamsin depressions coming from Sahara. Secondary maxima is observed in summer and autumn at DNC and MC (Barrani and Arish) stations in summer due to dust haze which prevails during that season and at UC (Cairo) in autumn, due to the northern extension of the Sudan monsoon trough, which is accompanied by small-scale depressions with dust particles. The mean annual values of β, δ a , and T L (0.216, 0.314, and 4.6, respectively) are larger in Cairo than at MC stations (0.146, 0.216, and 3.8, respectively) and DNC stations (0.153, 0.227, and 3.8, respectively). Both El-Chichon and Mt. Pinatubo eruptions were examined for all records data at MC, UC and DNC stations. The overburden caused by Mt. Pinatubo's eruption was larger than El-Chichon's eruption and overburden for β, and T L at DNC stations (0.06, and 0.58 units, respectively) was more pronounced than that at MC (0.02, and 0.26, respectively) and UC (0.05 and 0.52 units, respectively) stations. The annual variations in wind speed and turbidity parameters show high values for both low and high wind speed at all stations

  3. Estimating dissolved organic carbon concentration in turbid coastal waters using optical remote sensing observations

    NASA Astrophysics Data System (ADS)

    Cherukuru, Nagur; Ford, Phillip W.; Matear, Richard J.; Oubelkheir, Kadija; Clementson, Lesley A.; Suber, Ken; Steven, Andrew D. L.

    2016-10-01

    Dissolved Organic Carbon (DOC) is an important component in the global carbon cycle. It also plays an important role in influencing the coastal ocean biogeochemical (BGC) cycles and light environment. Studies focussing on DOC dynamics in coastal waters are data constrained due to the high costs associated with in situ water sampling campaigns. Satellite optical remote sensing has the potential to provide continuous, cost-effective DOC estimates. In this study we used a bio-optics dataset collected in turbid coastal waters of Moreton Bay (MB), Australia, during 2011 to develop a remote sensing algorithm to estimate DOC. This dataset includes data from flood and non-flood conditions. In MB, DOC concentration varied over a wide range (20-520 μM C) and had a good correlation (R2 = 0.78) with absorption due to coloured dissolved organic matter (CDOM) and remote sensing reflectance. Using this data set we developed an empirical algorithm to derive DOC concentrations from the ratio of Rrs(412)/Rrs(488) and tested it with independent datasets. In this study, we demonstrate the ability to estimate DOC using remotely sensed optical observations in turbid coastal waters.

  4. Analytical Capability of Defocused µ-SORS in the Chemical Interrogation of Thin Turbid Painted Layers

    PubMed Central

    Realini, Marco; Botteon, Alessandra; Colombo, Chiara; Noll, Sarah; Elliott, Stephen R.; Matousek, Pavel

    2016-01-01

    A recently developed micrometer-scale spatially offset Raman spectroscopy (μ-SORS) method provides a new analytical capability for investigating non-destructively the chemical composition of sub-surface, micrometer-scale thickness, diffusely scattering layers at depths beyond the reach of conventional confocal Raman microscopy. Here, we demonstrate experimentally, for the first time, the capability of μ-SORS to determine whether two detected chemical components originate from two separate layers or whether the two components are mixed together in a single layer. Such information is important in a number of areas, including conservation of cultural heritage objects, and is not available, for highly turbid media, from conventional Raman microscopy, where axial (confocal) scanning is not possible due to an inability to facilitate direct imaging within the highly scattering sample. This application constitutes an additional capability for μ-SORS in addition to its basic capacity to determine the overall chemical make-up of layers in a turbid system. PMID:26767641

  5. Optical monitoring of chemical processes in turbid biogenic liquid dispersions by Photon Density Wave spectroscopy.

    PubMed

    Hass, Roland; Munzke, Dorit; Ruiz, Salomé Vargas; Tippmann, Johannes; Reich, Oliver

    2015-04-01

    In turbid biogenic liquid material, like blood or milk, quantitative optical analysis is often strongly hindered by multiple light scattering resulting from cells, particles, or droplets. Here, optical attenuation is caused by losses due to absorption as well as scattering of light. Fiber-based Photon Density Wave (PDW) spectroscopy is a very promising method for the precise measurement of the optical properties of such materials. They are expressed as absorption and reduced scattering coefficients (μ a and μ s', respectively) and are linked to the chemical composition and physical properties of the sample. As a process analytical technology, PDW spectroscopy can sense chemical and/or physical processes within such turbid biogenic liquids, providing new scientific insight and process understanding. Here, for the first time, several bioprocesses are analyzed by PDW spectroscopy and the resulting optical coefficients are discussed with respect to established mechanistic models of the chosen processes. As model systems, enzymatic casein coagulation in milk, temperature-induced starch hydrolysis in beer mash, and oxy- as well as deoxygenation of human donor blood were investigated by PDW spectroscopy. The findings indicate that also for very complex biomaterials (i.e., not well-defined model materials like monodisperse polymer dispersions), obtained optical coefficients allow for the assessment of a structure/process relationship and thus for a new analytical access to biogenic liquid material. This is of special relevance as PDW spectroscopy data are obtained without any dilution or calibration, as often found in conventional spectroscopic approaches.

  6. An improved profiling method for the measurement of hyperspectral diffuse attenuation coefficents in shallow turbid waters

    NASA Astrophysics Data System (ADS)

    Ma, Li; Tao, Bangyi; Shi, Liangliang; Zhu, Qiankun

    2016-10-01

    The measurement of hyperspectral diffuse attenuation coefficients (Kd(λ)) in shallow turbid waters cannot be successfully achieved by the original Satlantic profiling system, because of less data available in the near-surface waters due to the rapid decrease of light intensity. In this paper, an improved profiling system and processing method are proposed. Firstly, a convenient buoyancy device is designed and mounted on the Satlantic Profiler II to allow the profiler to loiter close to the sea surface, thereby significantly improving the vertical sampling resolution to 1cm/s in near-surface waters, particularly in the depth between 0 and 1 meter. In addition, customized processing software CProSoft is developed to subjectively select the depths for various wavelengths that meet their different requirement for regression analysis. Comparison with original system results shows that our novel method can significantly improve the accuracy of Kd(λ) measurements especially in the short blue and red spectral range, and can even effectively derive near-surface Kd values in the extremely turbid waters with attenuation coefficients greater than 30 m-1, which dramatically enlarge the Kd(λ) measuring range

  7. Four decades of variability in turbidity in the western Wadden Sea as derived from corrected Secchi disk readings

    NASA Astrophysics Data System (ADS)

    Philippart, Catharina J. M.; Salama, Mhd. Suhyb; Kromkamp, Jacco C.; van der Woerd, Hendrik J.; Zuur, Alain F.; Cadée, Gerhard C.

    2013-09-01

    The Wadden Sea has undergone many changes of which some (e.g., seagrass disappearance, dredging activities) are thought to have affected the concentrations of suspended particulate matter (SPM) in these waters. Results of previous analyses of long-term variation and trends in SPM are, however, possibly biased by the fact that the data underlying these trends were not corrected for methodological changes in time. In this paper we analyze the variability of Secchi disk measurements recorded at one location in the westernmost part of the Wadden Sea during almost four decades (from 1974 to 2010). The Secchi readings were corrected for varying environmental conditions (solar zenith angle, solar irradiance and sea surface conditions) at the time of observation and then converted to a turbidity proxy that measures the attenuation of light due to suspended and dissolved materials in the water column. We tested a series of hypotheses to describe the seasonal and long-term variations of this turbidity proxy. The best statistical model assumed one common seasonal pattern within the study period and a strong variation in turbidity over the years without any apparent long-term increase or decrease in time (n = 1361; r2 = 0.53). In addition, we found that most of the turbidity variation in this part of the Wadden Sea can be described as a function of SPM, chlorophyll-a, salinity, water temperature, the filter type used for the SPM determinations, and a still unidentified seasonal factor (n = 401; r2 = 0.88). Comparison with annual averaged ADCP-derived SPM concentrations as determined from a ferry sailing across the Marsdiep tidal inlet (1998-2008) showed that the variability in turbidity at the sampling station was indicative for the variation in light attenuation in the westernmost part of the Wadden Sea. Because the intensity of the underwater light-field affects primary productivity, this new and consistent information on long-term variation in turbidity is of profound

  8. Towards environmental management of water turbidity within open coastal waters of the Great Barrier Reef.

    PubMed

    Macdonald, Rachael K; Ridd, Peter V; Whinney, James C; Larcombe, Piers; Neil, David T

    2013-09-15

    Water turbidity and suspended sediment concentration (SSC) are commonly used as part of marine monitoring and water quality plans. Current management plans utilise threshold SSC values derived from mean-annual turbidity concentrations. Little published work documents typical ranges of turbidity for reefs within open coastal waters. Here, time-series turbidity measurements from 61 sites in the Great Barrier Reef (GBR) and Moreton Bay, Australia, are presented as turbidity exceedance curves and derivatives. This contributes to the understanding of turbidity and SSC in the context of environmental management in open-coastal reef environments. Exceedance results indicate strong spatial and temporal variability in water turbidity across inter/intraregional scales. The highest turbidity across 61 sites, at 50% exceedance (T50) is 15.3 NTU and at 90% exceedance (T90) 4.1 NTU. Mean/median turbidity comparisons show strong differences between the two, consistent with a strongly skewed turbidity regime. Results may contribute towards promoting refinement of water quality management protocols.

  9. Apparatus and method for qualitative and quantitative measurements of optical properties of turbid media using frequency-domain photon migration

    DOEpatents

    Tromberg, Bruce J.; Tsay, Tsong T.; Berns, Michael W.; Svaasand, Lara O.; Haskell, Richard C.

    1995-01-01

    Optical measurements of turbid media, that is media characterized by multiple light scattering, is provided through an apparatus and method for exposing a sample to a modulated laser beam. The light beam is modulated at a fundamental frequency and at a plurality of integer harmonics thereof. Modulated light is returned from the sample and preferentially detected at cross frequencies at frequencies slightly higher than the fundamental frequency and at integer harmonics of the same. The received radiance at the beat or cross frequencies is compared against a reference signal to provide a measure of the phase lag of the radiance and modulation ratio relative to a reference beam. The phase and modulation amplitude are then provided as a frequency spectrum by an array processor to which a computer applies a complete curve fit in the case of highly scattering samples or a linear curve fit below a predetermined frequency in the case of highly absorptive samples. The curve fit in any case is determined by the absorption and scattering coefficients together with a concentration of the active substance in the sample. Therefore, the curve fitting to the frequency spectrum can be used both for qualitative and quantitative analysis of substances in the sample even though the sample is highly turbid.

  10. Apparatus and method for qualitative and quantitative measurements of optical properties of turbid media using frequency-domain photon migration

    DOEpatents

    Tromberg, B.J.; Tsay, T.T.; Berns, M.W.; Svaasand, L.O.; Haskell, R.C.

    1995-06-13

    Optical measurements of turbid media, that is media characterized by multiple light scattering, is provided through an apparatus and method for exposing a sample to a modulated laser beam. The light beam is modulated at a fundamental frequency and at a plurality of integer harmonics thereof. Modulated light is returned from the sample and preferentially detected at cross frequencies at frequencies slightly higher than the fundamental frequency and at integer harmonics of the same. The received radiance at the beat or cross frequencies is compared against a reference signal to provide a measure of the phase lag of the radiance and modulation ratio relative to a reference beam. The phase and modulation amplitude are then provided as a frequency spectrum by an array processor to which a computer applies a complete curve fit in the case of highly scattering samples or a linear curve fit below a predetermined frequency in the case of highly absorptive samples. The curve fit in any case is determined by the absorption and scattering coefficients together with a concentration of the active substance in the sample. Therefore, the curve fitting to the frequency spectrum can be used both for qualitative and quantitative analysis of substances in the sample even though the sample is highly turbid. 14 figs.

  11. Island building in the South China Sea: detection of turbidity plumes and artificial islands using Landsat and MODIS data.

    PubMed

    Barnes, Brian B; Hu, Chuanmin

    2016-09-15

    The South China Sea is currently in a state of intense geopolitical conflict, with six countries claiming sovereignty over some or all of the area. Recently, several countries have carried out island building projects in the Spratly Islands, converting portions of coral reefs into artificial islands. Aerial photography and high resolution satellites can capture snapshots of this construction, but such data are lacking in temporal resolution and spatial scope. In contrast, lower resolution satellite sensors with regular repeat sampling allow for more rigorous assessment and monitoring of changes to the reefs and surrounding areas. Using Landsat-8 data at ≥15-m resolution, we estimated that over 15 km(2) of submerged coral reef area was converted to artificial islands between June 2013 and December 2015, mostly by China. MODIS data at ≥250-m resolution were used to locate previously underreported island building activities, as well as to assess resulting in-water turbidity plumes. The combined spatial extent of observed turbidity plumes for island building activities at Mischief, Subi, and Fiery Cross Reefs was over 4,300 km(2), although nearly 40% of this area was only affected once. Together, these activities represent widespread damage to coral ecosystems through physical burial as well as indirect turbidity effects.

  12. Island building in the South China Sea: detection of turbidity plumes and artificial islands using Landsat and MODIS data

    PubMed Central

    Barnes, Brian B.; Hu, Chuanmin

    2016-01-01

    The South China Sea is currently in a state of intense geopolitical conflict, with six countries claiming sovereignty over some or all of the area. Recently, several countries have carried out island building projects in the Spratly Islands, converting portions of coral reefs into artificial islands. Aerial photography and high resolution satellites can capture snapshots of this construction, but such data are lacking in temporal resolution and spatial scope. In contrast, lower resolution satellite sensors with regular repeat sampling allow for more rigorous assessment and monitoring of changes to the reefs and surrounding areas. Using Landsat-8 data at ≥15-m resolution, we estimated that over 15 km2 of submerged coral reef area was converted to artificial islands between June 2013 and December 2015, mostly by China. MODIS data at ≥250-m resolution were used to locate previously underreported island building activities, as well as to assess resulting in-water turbidity plumes. The combined spatial extent of observed turbidity plumes for island building activities at Mischief, Subi, and Fiery Cross Reefs was over 4,300 km2, although nearly 40% of this area was only affected once. Together, these activities represent widespread damage to coral ecosystems through physical burial as well as indirect turbidity effects. PMID:27628096

  13. Island building in the South China Sea: detection of turbidity plumes and artificial islands using Landsat and MODIS data

    NASA Astrophysics Data System (ADS)

    Barnes, Brian B.; Hu, Chuanmin

    2016-09-01

    The South China Sea is currently in a state of intense geopolitical conflict, with six countries claiming sovereignty over some or all of the area. Recently, several countries have carried out island building projects in the Spratly Islands, converting portions of coral reefs into artificial islands. Aerial photography and high resolution satellites can capture snapshots of this construction, but such data are lacking in temporal resolution and spatial scope. In contrast, lower resolution satellite sensors with regular repeat sampling allow for more rigorous assessment and monitoring of changes to the reefs and surrounding areas. Using Landsat-8 data at ≥15-m resolution, we estimated that over 15 km2 of submerged coral reef area was converted to artificial islands between June 2013 and December 2015, mostly by China. MODIS data at ≥250-m resolution were used to locate previously underreported island building activities, as well as to assess resulting in-water turbidity plumes. The combined spatial extent of observed turbidity plumes for island building activities at Mischief, Subi, and Fiery Cross Reefs was over 4,300 km2, although nearly 40% of this area was only affected once. Together, these activities represent widespread damage to coral ecosystems through physical burial as well as indirect turbidity effects.

  14. Turbidity-current channels in Queen Inlet, Glacier Bay, Alaska

    USGS Publications Warehouse

    Carlson, P.R.; Powell, R.D.; Rearic, D.M.

    1989-01-01

    Queen Inlet is unique among Glacier Bay fjords because it alone has a branching channel system incised in the Holocene sediment fill of the fjord floor. Queen Inlet and other known channel-containing fjords are marine-outwash fjords; the tidewater glacial fjords do not have steep delta fronts on which slides are generated and may not have a sufficient reservoir of potentially unstable coarse sediment to generate channel-cutting turbidity currents. Presence or absence of channels, as revealed in the ancient rock record, may be one criterion for interpreting types of fjords. -Authors

  15. Free space propagation of concentric vortices through underwater turbid environments

    NASA Astrophysics Data System (ADS)

    Morgan, K. S.; Miller, J. K.; Cochenour, B. M.; Li, W.; Li, Y.; Watkins, R. J.; Johnson, E. G.

    2016-10-01

    Concentric optical vortex beams of 3-petal, 5-petal, and 6-petal spatial profiles are generated at 450 nm using a single diffractive optical element. The spatial and temporal propagation characteristics of these beams are then studied in a scattering underwater environment. Experimental results demonstrate a less than 5% reduction in the spatial pattern for turbidities in excess of 10 attenuation lengths. The temporal properties of concentric vortex beams are studied by temporally encoding an on-off keyed, non-return-to-zero (OOK-NRZ) data stream at 1.5 GHz.

  16. Landsat Thematic Mapper monitoring of turbid inland water quality

    NASA Technical Reports Server (NTRS)

    Lathrop, Richard G., Jr.

    1992-01-01

    This study reports on an investigation of water quality calibration algorithms under turbid inland water conditions using Landsat Thematic Mapper (TM) multispectral digital data. TM data and water quality observations (total suspended solids and Secchi disk depth) were obtained near-simultaneously and related using linear regression techniques. The relationships between reflectance and water quality for Green Bay and Lake Michigan were compared with results for Yellowstone and Jackson Lakes, Wyoming. Results show similarities in the water quality-reflectance relationships, however, the algorithms derived for Green Bay - Lake Michigan cannot be extrapolated to Yellowstone and Jackson Lake conditions.

  17. Digital optical phase conjugation of fluorescence in turbid tissue

    SciTech Connect

    Vellekoop, Ivo M.; Cui Meng; Yang Changhuei

    2012-08-20

    We demonstrate a method for phase conjugating fluorescence. Our method, called reference free digital optical phase conjugation, can conjugate extremely weak, incoherent optical signals. It was used to phase conjugate fluorescent light originating from a bead covered with 0.5 mm of light-scattering tissue. The phase conjugated beam refocuses onto the bead and causes a local increase of over two orders of magnitude in the light intensity. Potential applications are in imaging, optical trapping, and targeted photochemical activation inside turbid tissue.

  18. Time-resolved photon emission from layered turbid media

    SciTech Connect

    Hielscher, A.H.; Liu, H.; Chance, B.; Tittel, F.K.; Jacques, S.L.

    1996-02-01

    We present numerical and experimental results of time-resolved emission profiles from various layered turbid media. Numerical solutions determined by time-resolved Monte Carlo simulations are compared with measurements on layered-tissue phantoms made from gelatin. In particular, we show that in certain cases the effects of the upper layers can be eliminated. As a practical example, these results are used to analyze {ital in} {ital vivo} measurements on the human head. This demonstrates the influence of skin, skull, and meninges on the determination of the blood oxygenation in the brain. {copyright} {ital 1996 Optical Society of America.}

  19. Laboratory observations of saline and turbidity currents flowing in U-shaped flume

    NASA Astrophysics Data System (ADS)

    Stagnaro, M.; Bolla Pittaluga, M.

    2013-12-01

    Saline and turbidity currents belong to the large family of gravity currents. Due to the difficulties to predict and observe these kinds of phenomena, especially turbidity currents, we developed an experimental apparatus able to reproduce these currents in our Marchi Environmental Laboratory (Genova, Italy). The experiments were performed in a large U-shaped flume, 30 m long, characterized by a constant curvature bend (radius of 2.5 m) joining two straight reaches approximately 12 m long. The flume has a rectangular cross section 0.6 m wide and 0.5 m deep. Inside the flume we made a uniform concrete bottom slope (0.005), which proceeds from the inlet section along the first straight track and finishes 3 m after the bend exit. For each experiment we have been able to measure density distribution and velocity profiles along the vertical in different cross section. Density measurements were obtained using two ranks of siphons that sample the currents at different heights. Velocity was acquired with the DOP2000 ultrasound velocimeter; we measured longitudinal component in the straight reach of the flume, and both longitudinal and transversal velocity in the curved reach. We performed 30 experiments by changing the inlet conditions: primary defining the nature of the currents, saline or sediment laden, then varying two of the main parameters governing the currents: the density of the mixture and the flow discharge. The former covered a range between 1003 and 1023 kg/m^3 and the flow discharge ranged between 0.5 to 4.0 l/s. Both of these parameters influence the densimetric Froude Number, and allowed us to reproduce both subcritical and supercritical flow. In each experiment water entrainment from above was negligible hence the current was able to attain a quasi-uniform configuration in the first straight reach, whereby the longitudinal velocity and the thickness of the current were approximately constant. By varying the inlet conditions, it was possible to observe the

  20. Predicting Recreational Water Quality Using Turbidity in the Cuyahoga River, Cuyahoga Valley National Park, Ohio, 2004-7

    USGS Publications Warehouse

    Brady, Amie M.G.; Bushon, Rebecca N.; Plona, Meg B.

    2009-01-01

    The Cuyahoga River within Cuyahoga Valley National Park (CVNP) in Ohio is often impaired for recreational use because of elevated concentrations of bacteria, which are indicators of fecal contamination. During the recreational seasons (May through August) of 2004 through 2007, samples were collected at two river sites, one upstream of and one centrally-located within CVNP. Bacterial concentrations and turbidity were determined, and streamflow at time of sampling and rainfall amounts over the previous 24 hours prior to sampling were ascertained. Statistical models to predict Escherichia coli (E. coli) concentrations were developed for each site (with data from 2004 through 2006) and tested during an independent year (2007). At Jaite, a sampling site near the center of CVNP, the predictive model performed better than the traditional method of determining the current day's water quality using the previous day's E. coli concentration. During 2007, the Jaite model, based on turbidity, produced more correct responses (81 percent) and fewer false negatives (3.2 percent) than the traditional method (68 and 26 percent, respectively). At Old Portage, a sampling site just upstream from CVNP, a predictive model with turbidity and rainfall as explanatory variables did not perform as well as the traditional method. The Jaite model was used to estimate water quality at three other sites in the park; although it did not perform as well as the traditional method, it performed well - yielding between 68 and 91 percent correct responses. Further research would be necessary to determine whether using the Jaite model to predict recreational water quality elsewhere on the river would provide accurate results.

  1. Correlations of turbidity to suspended-sediment concentration in the Toutle River Basin, near Mount St. Helens, Washington, 2010-11

    USGS Publications Warehouse

    Uhrich, Mark A.; Kolasinac, Jasna; Booth, Pamela L.; Fountain, Robert L.; Spicer, Kurt R.; Mosbrucker, Adam R.

    2014-01-01

    Researchers at the U.S. Geological Survey, Cascades Volcano Observatory, investigated alternative methods for the traditional sample-based sediment record procedure in determining suspended-sediment concentration (SSC) and discharge. One such sediment-surrogate technique was developed using turbidity and discharge to estimate SSC for two gaging stations in the Toutle River Basin near Mount St. Helens, Washington. To provide context for the study, methods for collecting sediment data and monitoring turbidity are discussed. Statistical methods used include the development of ordinary least squares regression models for each gaging station. Issues of time-related autocorrelation also are evaluated. Addition of lagged explanatory variables was used to account for autocorrelation in the turbidity, discharge, and SSC data. Final regression model equations and plots are presented for the two gaging stations. The regression models support near-real-time estimates of SSC and improved suspended-sediment discharge records by incorporating continuous instream turbidity. Future use of such models may potentially lower the costs of sediment monitoring by reducing time it takes to collect and process samples and to derive a sediment-discharge record.

  2. High-extinction virtually imaged phased array-based Brillouin spectroscopy of turbid biological media.

    PubMed

    Fiore, Antonio; Zhang, Jitao; Shao, Peng; Yun, Seok Hyun; Scarcelli, Giuliano

    2016-05-16

    Brillouin microscopy has recently emerged as a powerful technique to characterize the mechanical properties of biological tissue, cell, and biomaterials. However, the potential of Brillouin microscopy is currently limited to transparent samples, because Brillouin spectrometers do not have sufficient spectral extinction to reject the predominant non-Brillouin scattered light of turbid media. To overcome this issue, we combined a multi-pass Fabry-Perot interferometer with a two-stage virtually imaged phased array spectrometer. The Fabry-Perot etalon acts as an ultra-narrow band-pass filter for Brillouin light with high spectral extinction and low loss. We report background-free Brillouin spectra from Intralipid solutions and up to 100 μm deep within chicken muscle tissue.

  3. Comprehensive analytical model for CW laser induced heat in turbid media

    PubMed Central

    Erkol, Hakan; Nouizi, Farouk; Luk, Alex; Unlu, Mehmet Burcin; Gulsen, Gultekin

    2015-01-01

    In this work, we present a new analytical approach to model continuous wave laser induced temperature in highly homogeneous turbid media. First, the diffusion equation is used to model light transport and a comprehensive solution is derived analytically by obtaining a special Greens’ function. Next, the time-dependent bio-heat equation is used to describe the induced heat increase and propagation within the medium. The bio-heat equation is solved analytically utilizing the separation of variables technique. Our theoretical model is successfully validated using numerical simulations and experimental studies with agarose phantoms and ex-vivo chicken breast samples. The encouraging results show that our method can be implemented as a simulation tool to determine important laser parameters that govern the magnitude of temperature rise within homogenous biological tissue or organs. PMID:26698736

  4. Low Frequency Vibrating Optical System for Detecting Objects Buried in Turbid Media: Preliminary Results

    NASA Astrophysics Data System (ADS)

    Cywiak, D.; Cywiak, M.; Pérez-Solano, R.; Gutiérrez-Juárez, G.

    2012-11-01

    Preliminary results of an in-plane vibrating system to image objects buried in turbid media are presented. The incident optical beam is vibrated in a periodic back-and-forth motion at low frequency and small constant amplitude in a plane perpendicular to the direction of the beam. The detection is performed in the AC mode, blocking the DC component. The system shows a dramatic increase in the AC signal whenever the target boundary intersects with the reference line between the incident laser beam and a photodiode after a small aperture. The system was capable to render visible 2 mm width objects buried at depths up to 3 cm from the front surface of a 1% intralipid sample.

  5. High-extinction virtually imaged phased array-based Brillouin spectroscopy of turbid biological media

    NASA Astrophysics Data System (ADS)

    Fiore, Antonio; Zhang, Jitao; Shao, Peng; Yun, Seok Hyun; Scarcelli, Giuliano

    2016-05-01

    Brillouin microscopy has recently emerged as a powerful technique to characterize the mechanical properties of biological tissue, cell, and biomaterials. However, the potential of Brillouin microscopy is currently limited to transparent samples, because Brillouin spectrometers do not have sufficient spectral extinction to reject the predominant non-Brillouin scattered light of turbid media. To overcome this issue, we combined a multi-pass Fabry-Perot interferometer with a two-stage virtually imaged phased array spectrometer. The Fabry-Perot etalon acts as an ultra-narrow band-pass filter for Brillouin light with high spectral extinction and low loss. We report background-free Brillouin spectra from Intralipid solutions and up to 100 μm deep within chicken muscle tissue.

  6. Prospects of coherent control in turbid media: Bounds on focusing broadband laser pulses

    SciTech Connect

    Shapiro, Evgeny A.; Drane, Thomas M.; Milner, Valery

    2011-11-15

    We study the prospects of controlling transmission of broadband and bichromatic laser pulses through turbid samples. The ability to focus transmitted broadband light is limited via both the scattering properties of the medium and the technical characteristics of the experimental setup. There are two time scales given by pulse stretching in the near- and far-field regions which define the maximum bandwidth of a pulse amenable to focusing. In the geometric-optics regime of wave propagation in the medium, a single setup can be optimal for focusing light at frequencies {omega} and n{omega} simultaneously, providing the basis for the 1+n coherent quantum control. Beyond the regime of geometric optics, we discuss a simple solution for the shaping, which provides the figure of merit for one's ability to simultaneously focus several transmission modes.

  7. Comprehensive analytical model for CW laser induced heat in turbid media.

    PubMed

    Erkol, Hakan; Nouizi, Farouk; Luk, Alex; Unlu, Mehmet Burcin; Gulsen, Gultekin

    2015-11-30

    In this work, we present a new analytical approach to model continuous wave laser induced temperature in highly homogeneous turbid media. First, the diffusion equation is used to model light transport and a comprehensive solution is derived analytically by obtaining a special Greens' function. Next, the time-dependent bio-heat equation is used to describe the induced heat increase and propagation within the medium. The bio-heat equation is solved analytically utilizing the separation of variables technique. Our theoretical model is successfully validated using numerical simulations and experimental studies with agarose phantoms and ex-vivo chicken breast samples. The encouraging results show that our method can be implemented as a simulation tool to determine important laser parameters that govern the magnitude of temperature rise within homogenous biological tissue or organs.

  8. Monte Carlo simulation of optical coherence tomography for turbid media with arbitrary spatial distributions.

    PubMed

    Malektaji, Siavash; Lima, Ivan T; Sherif, Sherif S

    2014-04-01

    We developed a Monte Carlo-based simulator of optical coherence tomography (OCT) imaging for turbid media with arbitrary spatial distributions. This simulator allows computation of both Class I diffusive reflectance due to ballistic and quasiballistic scattered photons and Class II diffusive reflectance due to multiple scattered photons. It was implemented using a tetrahedron-based mesh and importance sampling to significantly reduce computational time. Our simulation results were verified by comparing them with results from two previously validated OCT simulators for multilayered media. We present simulation results for OCT imaging of a sphere inside a background slab, which would not have been possible with earlier simulators. We also discuss three important aspects of our simulator: (1) resolution, (2) accuracy, and (3) computation time. Our simulator could be used to study important OCT phenomena and to design OCT systems with improved performance.

  9. Interrelation of surface tension, optical turbidity, and color of operational transformer oils

    SciTech Connect

    L'vov, S. Yu.; Lyut'ko, E. O.; Lankau, Ya. V.; Komarov, V. B.; Seliverstov, A. F.; Bondareva, V. N.; L'vov, Yu. N.; L'vov, M. Yu.; Ershov, B. G.

    2011-09-15

    Measurements of the acidity, optical turbidity, surface tension, and color of transformer oil from 54 power transformers, autotransformers, and shunt reactors are reported. Changes in surface tension, optical turbidity, and color are found to obey adequate linear correlations, while the acidity has no correlation with any of these properties. Numerical criteria for the maximum permissible state (quality) of the oil with respect to optical turbidity and color are obtained. Recommendations to operating staff are provided for cases in which the criteria for optical turbidity and color are exceeded.

  10. An innovative process to improve turbidity and Organics Removal by BAC filters

    NASA Astrophysics Data System (ADS)

    Miao, Jia; Zhao, Qingliang; Wang, Baozhen; Li, Ji; Zhang, Jinsong

    2006-10-01

    The turbidity criterion for the product water of a WTP according to the State Project ‘863’ on the safeguard technology of drinking water in the southern areas of China is 0.1 NTU. The turbidity removal in the activated carbon filter was analyzed in a pilot-scale test and an innovative technology to improve the turbidity removal in a biologically activated carbon (BAC) filter was put forward in order to meet the criterion. Experimental results showed that the enhanced filtration by adding polymerized aluminium chloride (PAC) into the BAC filter was quite effective in turbidity control. The effluent turbidity was kept at a stable level (mean) of 0.033 NTU with a high removal of about 80% for influent turbidity of 0.110 0240 NTU with an addition of PAC at 0.05 mg L-1, meeting the requirement for filtrate turbidity equal to or less than 0.1 NTUC totally. In addition, the larger the PAC dosage was, the lower the effluent turbidity was. However, further improvement of turbidity removal was not obvious for PAC dosages beyond 0.l0 mg L-, and an optimal PAC dosage in the range of 0.05 0.10 mg L- was proposed.

  11. Assessing the risk posed by high-turbidity water to water supplies.

    PubMed

    Chang, Chia-Ling; Liao, Chung-Sheng

    2012-05-01

    The objective of this study is to assess the risk of insufficient water supply posed by high-turbidity water. Several phenomena can pose risks to the sufficiency of a water supply; this study concerns risks to water treatment plants from particular properties of rainfall and raw water turbidity. High-turbidity water can impede water treatment plant operations; rainfall properties can influence the degree of soil erosion. Thus, water turbidity relates to rainfall characteristics. Exceedance probabilities are presented for different rainfall intensities and turbidities of water. When the turbidity of raw water is higher than 5,000 NTU, it can cause operational problems for a water treatment plant. Calculations show that the turbidity of raw water at the Ban-Sin water treatment plant will be higher than 5,000 NTU if the rainfall intensity is larger than 165 mm/day. The exceedance probability of high turbidity (turbidity >5,000 NTU) in the Ban-Sin water treatment plant is larger than 10%. When any water treatment plant cannot work regularly, its ability to supply water to its customers is at risk.

  12. Turbid Media Extinction Coefficient for Near-Infrared Laser Radiation

    NASA Astrophysics Data System (ADS)

    Dreischuh, T.; Gurdev, L.; Vankov, O.; Stoyanov, D.; Avramov, L.

    2015-03-01

    In this work, extended investigations are performed of the extinction coefficient of Intralipid-20% dilutions in distilled water depending on the Intralipid concentration, for laser radiation wavelengths in the red and near-infrared regions covering the so-called tissue optical window. The extinction is measured by using an approach we have developed recently based on the features of the spatial intensity distribution of laser-radiation beams propagating through semi-infinite turbid media. The measurements are conducted using separately two dilution- containing plexiglass boxes of different sizes and volumes, in order to prove the appropriateness of the assumption of semi-infinite turbid medium. The experimental results for the extinction are in agreement with our previous results and with empiric formulae found by other authors concerning the wavelength dependence of the scattering coefficient of Intralipid - 10% and Intralipid - 20%. They are also in agreement with known data of the water absorptance. It is estimated as well that the wavelengths around 1320 nm would be advantageous for deep harmless sensing and diagnostics of tissues.

  13. Backscattering of ultrashort laser pulse in turbid media

    NASA Astrophysics Data System (ADS)

    Narivonchik, Stanislav; Bespalov, Victor G.

    2002-01-01

    Recently there has been considerable interest in the problems of optical imaging in turbid, strongly scattering media, such as tumours in biological tissues, objects in water, etc. To detect objects in the media the analysis of backscattering of picosecond signal can be used. In this paper we report about the influence of medium parameters and detector parameters on temporal profile of the reflected pulse and its intensity. Virtual experiments were carried out with the MONTE-CARLO method, and temporal profile of signal was obtained. The dependencies of the forepart and tail-part of the signal fronts, maximum position of the reflected signal and the reflection coefficient from the scattering particle density and cross section were obtained. These dependencies show that the tail-part of the signal is greatly decreased while the density is increased, compared to the forepart and maximum intensity position of the signal. These results can be used to analyze the scattering particle density and cross section in the turbid materials. Virtual experiments with the presence of various inhomogeneities were performed, which show that not only reflecting and absorbing solid objects, but also even density inhomogeneities can be detected.

  14. Photometric and polarimetric mapping of water turbidity and water depth

    NASA Technical Reports Server (NTRS)

    Halajian, J.; Hallock, H.

    1973-01-01

    A Digital Photometric Mapper (DPM) was used in the Fall of 1971 in an airborne survey of New York and Boston area waters to acquire photometric, spectral and polarimetric data. The object of this study is to analyze these data with quantitative computer processing techniques to assess the potential of the DPM in the measurement and regional mapping of water turbidity and depth. These techniques have been developed and an operational potential has been demonstrated. More emphasis is placed at this time on the methodology of data acquisition, analysis and display than on the quantity of data. The results illustrate the type, quantity and format of information that could be generated operationally with the DPM-type sensor characterized by high photometric stability and fast, accurate digital output. The prototype, single-channel DPM is suggested as a unique research tool for a number of new applications. For the operational mapping of water turbidity and depth, the merits of a multichannel DPM coupled with a laser system are stressed.

  15. Light propagation in a turbid medium with insonified microbubbles.

    PubMed

    Leung, Terence S; Honeysett, Jack E; Stride, Eleanor; Deng, Jing

    2013-01-01

    Surfactant stabilized microbubbles are widely used clinical contrast agents for ultrasound imaging. In this work, the light propagation through a turbid medium in the presence of microbubbles has been investigated. Through a series of experiments, it has been found that the optical attenuation is increased when the microbubbles in a turbid medium are insonified by ultrasound. Such microbubble enhanced optical attenuation is a function of both applied ultrasound pressure and microbubble concentration. To understand the mechanisms involved, a Monte Carlo (MC) model has been developed. Under ultrasound exposure, the sizes of microbubbles vary in space and time, and their dynamics are modeled by the Rayleigh-Plesset equation. By using Mie theory, the spatially and temporally varying optical scattering and scattering efficiency of microbubbles are determined based on the bubble sizes and internal refractive indices. The MC model is shown to effectively describe a medium with rapidly changing optical scattering, and the results are validated against both computational results using an N-layered diffusion equation model and experimental results using a clinical microbubble contrast agent (SonoVue®).

  16. Disinfection by-product formation and mitigation strategies in point-of-use chlorination of turbid and non-turbid waters in western Kenya.

    PubMed

    Lantagne, D S; Blount, B C; Cardinali, F; Quick, R

    2008-03-01

    Over 1.1 billion people in the world lack access to improved drinking water. Diarrheal and other waterborne diseases cause an estimated 2.2 million deaths per year. The Safe Water System (SWS) is a proven household water treatment intervention that reduces diarrheal disease incidence in users in developing countries. Because the SWS recommends the addition of sodium hypochlorite to unfiltered water sources, concerns have been raised about the potential long-term health effects of disinfection by-products to SWS users. This study investigated the production of trihalomethanes (THMs) in water treated with sodium hypochlorite from six sources used for drinking water in western Kenya. The turbidity values of these sources ranged from 4.23 NTU to 305 NTU. THM concentrations were analysed at 1, 8, and 24 hours after addition of sodium hypochlorite. No sample exceeded the World Health Organization (WHO) guideline values for any of the four THMs: chloroform, bromodichloromethane, dibromochloromethane, or bromoform. In addition, no sample exceeded the WHO additive total THM guideline value. These results clearly show that point-of-use chlorination of a variety of realistic source waters used for drinking did not lead to THM concentrations that pose a significant health risk to SWS users.

  17. The correlation and quantification of airborne spectroradiometer data to turbidity measurements at Lake Powell, Utah

    NASA Technical Reports Server (NTRS)

    Merry, C. J.

    1979-01-01

    A water sampling program was accomplished at Lake Powell, Utah, during June 1975 for correlation to multispectral data obtained with a 500-channel airborne spectroradiometer. Field measurements were taken of percentage of light transmittance, surface temperature, pH and Secchi disk depth. Percentage of light transmittance was also measured in the laboratory for the water samples. Analyses of electron micrographs and suspended sediment concentration data for four water samples located at Hite Bridge, Mile 168, Mile 150 and Bullfrog Bay indicated differences in the composition and concentration of the particulate matter. Airborne spectroradiometer multispectral data were analyzed for the four sampling locations. The results showed that: (1) as the percentage of light transmittance of the water samples decreased, the reflected radiance increased; and (2) as the suspended sediment concentration (mg/l) increased, the reflected radiance increased in the 1-80 mg/l range. In conclusion, valuable qualitative information was obtained on surface turbidity for the Lake Powell water spectra. Also, the reflected radiance measured at a wavelength of 0.58 micron was directly correlated to the suspended sediment concentration.

  18. Effet de la turbidité sur la dégradation des pigments phytoplanctoniques dans l'estuaire de la GirondeEffect of turbidity on phytoplanktonic pigments degradation in the Gironde Estuary

    NASA Astrophysics Data System (ADS)

    Lemaire, Emmanuelle; Abril, Gwenaël; De Wit, Rutger; Etcheber, Henri

    In the Gironde Estuary, most part of phytoplanktonic material carried by the rivers is mineralised in the maximum turbidity zone (MTZ). In order to follow the degradation of the phytoplanktonic material into the MTZ, we developed an in vitro approach based on the monitoring of phytoplanktonic pigments. Algal material from two chlorophytes ( Scenedesmus suspicatus Chaudat and Chlamydomonas sp.) was incubated in the dark during 28 days into water samples from the Gironde estuary MTZ, at variable suspended solid concentrations (SPM) as well as in a sterilised turbid sample. First order decay constants of chlorophylls a and b and lutein increased by a factor 3 to 5 between SPM of 0 and 3 g l-1. The production of pheophytin a in the presence of particles and the lack of degradation in the sterilised turbid sample confirmed the effect of attached bacteria on the particles. To cite this article: E. Lemaire et al., C. R. Geoscience 334 (2002) 251-258.

  19. Determination of thickness of thin turbid painted over-layers using micro-scale spatially offset Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Conti, Claudia; Realini, Marco; Colombo, Chiara; Botteon, Alessandra; Bertasa, Moira; Striova, Jana; Barucci, Marco; Matousek, Pavel

    2016-12-01

    We present a method for estimating the thickness of thin turbid layers using defocusing micro-spatially offset Raman spectroscopy (micro-SORS). The approach, applicable to highly turbid systems, enables one to predict depths in excess of those accessible with conventional Raman microscopy. The technique can be used, for example, to establish the paint layer thickness on cultural heritage objects, such as panel canvases, mural paintings, painted statues and decorated objects. Other applications include analysis in polymer, biological and biomedical disciplines, catalytic and forensics sciences where highly turbid overlayers are often present and where invasive probing may not be possible or is undesirable. The method comprises two stages: (i) a calibration step for training the method on a well characterized sample set with a known thickness, and (ii) a prediction step where the prediction of layer thickness is carried out non-invasively on samples of unknown thickness of the same chemical and physical make up as the calibration set. An illustrative example of a practical deployment of this method is the analysis of larger areas of paintings. In this case, first, a calibration would be performed on a fragment of painting of a known thickness (e.g. derived from cross-sectional analysis) and subsequently the analysis of thickness across larger areas of painting could then be carried out non-invasively. The performance of the method is compared with that of the more established optical coherence tomography (OCT) technique on identical sample set. This article is part of the themed issue "Raman spectroscopy in art and archaeology".

  20. An integrated approach to monitoring the effect of sediment and turbidity on aquatic biota and water quality in the New York City water supply

    NASA Astrophysics Data System (ADS)

    McHale, M. R.; Baldigo, B. P.; Smith, A. J.; Mukundan, R.; Siemion, J.; Mulvihill, C.

    2011-12-01

    The New York City water supply system provides drinking water to more than 9 million people. About 90 percent of New York City's water is supplied by six surface-water reservoirs in the Catskill Mountains in southeastern New York State. The Ashokan Reservoir is a focus of concern because high turbidity and suspended sediment concentration can affect the drinking water supply and the integrity of aquatic biota in the reservoir and its tributaries. The U.S. Geological Survey, New York State Department of Environmental Conservation, and New York City Department of Environmental Protection are collaborating to identify suspended sediment and turbidity source areas and evaluate the effectiveness of stream stabilization projects to improve water quality in the 497 square kilometer Upper Esopus Creek watershed, the primary source of water to the Ashokan Reservoir. This research combines point measurements of stream habitat, macroinvertebrate, periphyton, and fish population sampling, and water quality sampling with continuous turbidity measurements and watershed modeling to integrate point measurements temporally and spatially throughout the watershed. Preliminary results suggest that although stream stabilization projects appear to have reduced sediment and turbidity concentrations and improved aquatic habitat, interpreting results has been confounded by a series of large storms during the last several years. Indeed, storms large enough to reshape channel morphology can have long-lasting effects on sediment and turbidity concentrations and aquatic biota. This framework for integrating temporal and spatial point measurements using high frequency monitoring and watershed modeling appears to hold great promise to inform policy concerning the water supply of one of the world's largest cities.

  1. EVALUATION OF A TURBIDITY METER FOR USE AT THE DEFENSE WASTE PROCESSING FACILITY

    SciTech Connect

    Mahannah, R.; Edwards, T.

    2013-06-04

    Savannah River Remediation’s (SRR’s) Defense Waste Processing Facility (DWPF) Laboratory currently tests for sludge carry-over into the Recycle Collection Tank (RCT) by evaluating the iron concentration in the Slurry Mix Evaporator Condensate Tank (SMECT) and relating this iron concentration to the amount of sludge solids present. A new method was proposed for detecting the amount of sludge in the SMECT that involves the use of an Optek turbidity sensor. Waste Services Laboratory (WSL) personnel conducted testing on two of these units following a test plan developed by Waste Solidification Engineering (WSE). Both Optek units (SN64217 and SN65164) use sensor model AF16-N and signal converter model series C4000. The sensor body of each unit was modified to hold a standard DWPF 12 cc sample vial, also known as a “peanut” vial. The purpose of this testing was to evaluate the use of this model of turbidity sensor, or meter, to provide a measurement of the sludge solids present in the SMECT based upon samples from that tank. During discussions of the results from this study by WSE, WSL, and Savannah River National Laboratory (SRNL) personnel, an upper limit on the acceptable level of solids in SMECT samples was set at 0.14 weight percent (wt%). A “go/no-go” decision criterion was to be developed for the critical turbidity response, which is expressed in concentration units (CUs), for each Optek unit based upon the 0.14 wt% solids value. An acceptable or a “go” decision for the SMECT should reflect the situation that there is an identified risk (e.g. 5%) for a CU response from the Optek unit to be less than the critical CU value when the solids content of the SMECT is actually 0.14 wt% or greater, while a “no-go” determination (i.e., an Optek CU response above the critical CU value, a conservative decision relative to risk) would lead to additional evaluations of the SMECT to better quantify the possible solids content of the tank. Subsequent to the

  2. Evaluation Of A Turbidity Meter For Use At The Defense Waste Processing Facility

    SciTech Connect

    Mahannah, R. N.; Edwards, T. B.

    2013-01-15

    Savannah River Remediation's (SRR's) Defense Waste Processing Facility (DWPF) Laboratory currently tests for sludge carry-over into the Recycle Collection Tank (RCT) by evaluating the iron concentration in the Slurry Mix Evaporator Condensate Tank (SMECT) and relating this iron concentration to the amount of sludge solids present. A new method was proposed for detecting the amount of sludge in the SMECT that involves the use of an Optek turbidity sensor. Waste Services Laboratory (WSL) personnel conducted testing on two of these units following a test plan developed by Waste Solidification Engineering (WSE). Both Optek units (SN64217 and SN65164) use sensor model AF16-N and signal converter model series C4000. The sensor body of each unit was modified to hold a standard DWPF 12 cc sample vial, also known as a ''peanut'' vial. The purpose of this testing was to evaluate the use of this model of turbidity sensor, or meter, to provide a measurement of the sludge solids present in the SMECT based upon samples from that tank. During discussions of the results from this study by WSE, WSL, and Savannah River National Laboratory (SRNL) personnel, an upper limit on the acceptable level of solids in SMECT samples was set at 0.14 wt%. A ''go/no-go'' decision criterion was to be developed for the critical turbidity response, which is expressed in concentration units (CUs), for each Optek unit based upon the 0.14 wt% solids value. An acceptable or a ''go'' decision for the SMECT should reflect the situation that there is an identified risk (e.g. 5%) for a CU response from the Optek unit to be less than the critical CU value when the solids content of the SMECT is actually 0.14 wt% or greater, while a ''no-go'' determination (i.e., an Optek CU response above the critical CU value, a conservative decision relative to risk) would lead to additional evaluations of the SMECT to better quantify the possible solids content of the tank. A sludge simulant was used to develop standards

  3. Virus-bacterium coupling driven by both turbidity and hydrodynamics in an Amazonian floodplain lake.

    PubMed

    Barros, Nathan; Farjalla, Vinicius F; Soares, Maria C; Melo, Rossana C N; Roland, Fábio

    2010-11-01

    The importance of viruses in aquatic ecosystem functioning has been widely described. However, few studies have examined tropical aquatic ecosystems. Here, we evaluated for the first time viruses and their relationship with other planktonic communities in an Amazonian freshwater ecosystem. Coupling between viruses and bacteria was studied, focusing both on hydrologic dynamics and anthropogenic forced turbidity in the system (Lake Batata). Samples were taken during four hydrologic seasons at both natural and impacted sites to count virus-like particles (VLP) and bacteria. In parallel, virus-infected bacteria were identified and quantified by transmission electron microscopy (TEM). Viral abundance ranged from 0.5 × 10⁷ ± 0.2 × 10⁷ VLP ml⁻¹ (high-water season, impacted site) to 1.7 × 10⁷ ± 0.4 × 10⁷ VLP ml⁻¹ (low-water season, natural site). These data were strongly correlated with the bacterial abundance (r² = 0.84; P < 0.05), which ranged from 1.0 × 10⁶ ± 0.5 × 10⁶ cells ml⁻¹ (high water, impacted site) to 3.4 × 10⁶ ± 0.7 × 10⁶ cells ml⁻¹ (low water, natural site). Moreover, the viral abundance was weakly correlated with chlorophyll a, suggesting that most viruses were bacteriophages. TEM quantitative analyses revealed that the frequency of visibly infected cells was 20%, with 10 ± 3 phages per cell section. In general, we found a low virus-bacterium ratio (<7). Both the close coupling between the viral and bacterial abundances and the low virus-bacterium ratio suggest that viral abundance tends to be driven by the reduction of hosts for viral infection. Our results demonstrate that viruses are controlled by biological substrates, whereas in addition to grazing, bacteria are regulated by physical processes caused by turbidity, which affect underwater light distribution and dissolved organic carbon availability.

  4. Application of the adjoint approach to optimise the initial conditions of a turbidity current with the AdjointTurbidity 1.0 model

    NASA Astrophysics Data System (ADS)

    Parkinson, Samuel D.; Funke, Simon W.; Hill, Jon; Piggott, Matthew D.; Allison, Peter A.

    2017-03-01

    Turbidity currents are one of the main drivers of sediment transport from the continental shelf to the deep ocean. The resulting sediment deposits can reach hundreds of kilometres into the ocean. Computer models that simulate turbidity currents and the resulting sediment deposit can help us to understand their general behaviour. However, in order to recreate real-world scenarios, the challenge is to find the turbidity current parameters that reproduce the observations of sediment deposits. This paper demonstrates a solution to the inverse sediment transportation problem: for a known sedimentary deposit, the developed model reconstructs details about the turbidity current that produced the deposit. The reconstruction is constrained here by a shallow water sediment-laden density current model, which is discretised by the finite-element method and an adaptive time-stepping scheme. The model is differentiated using the adjoint approach, and an efficient gradient-based optimisation method is applied to identify the turbidity parameters which minimise the misfit between the modelled and the observed field sediment deposits. The capabilities of this approach are demonstrated using measurements taken in the Miocene Marnoso-arenacea Formation (Italy). We find that whilst the model cannot match the deposit exactly due to limitations in the physical processes simulated, it provides valuable insights into the depositional processes and represents a significant advance in our toolset for interpreting turbidity current deposits.

  5. Enhancement of Video Images Degraded by Turbid Water

    DTIC Science & Technology

    1986-12-01

    I o o i^ipipP^^iW^ NAVAL POSTGRADUATE SCHOOL Monterey, California THESIS ENHANCEMENT OF VIDEO IMAGES DEGRADED BY TURBID WATER by Jorge A...OUTPUT ARRAY » « • DOL = I.IHG DO M - 1 .IM6Y SALIDA (L.M) = 0 END DO END DO c c c c c c c TYPE «/OUTPUT ARRAY INITIALIZED’ CALL riCHECK...MM((J-1)»16>+1 IXX=LL+IX-1 IYY =MM+IY-1 SALIDA (IXX.IYY) = SALIDA (IXX.IYY>+INTE(IX.IY) TYPEMXX AND IYY =>’.IXX.IYY 50 ^&&J^i£aJ^^ ’» 100 c

  6. Laser ablation of a turbid medium: Modeling and experimental results

    SciTech Connect

    Brygo, F.; Semerok, A.; Weulersse, J.-M.; Thro, P.-Y.; Oltra, R.

    2006-08-01

    Q-switched Nd:YAG laser ablation of a turbid medium (paint) is studied. The optical properties (absorption coefficient, scattering coefficient, and its anisotropy) of a paint are determined with a multiple scattering model (three-flux model), and from measurements of reflection-transmission of light through thin layers. The energy deposition profiles are calculated at wavelengths of 532 nm and 1.064 {mu}m. They are different from those described by a Lambert-Beer law. In particular, the energy deposition of the laser beam is not maximum on the surface but at some depth inside the medium. The ablated rate was measured for the two wavelengths and compared with the energy deposition profile predicted by the model. This allows us to understand the evolution of the ablated depth with the wavelength: the more the scattering coefficient is higher, the more the ablated depth and the threshold fluence of ablation decrease.

  7. Markov chain solution of photon multiple scattering through turbid slabs.

    PubMed

    Lin, Ying; Northrop, William F; Li, Xuesong

    2016-11-14

    This work introduces a Markov Chain solution to model photon multiple scattering through turbid slabs via anisotropic scattering process, i.e., Mie scattering. Results show that the proposed Markov Chain model agree with commonly used Monte Carlo simulation for various mediums such as medium with non-uniform phase functions and absorbing medium. The proposed Markov Chain solution method successfully converts the complex multiple scattering problem with practical phase functions into a matrix form and solves transmitted/reflected photon angular distributions by matrix multiplications. Such characteristics would potentially allow practical inversions by matrix manipulation or stochastic algorithms where widely applied stochastic methods such as Monte Carlo simulations usually fail, and thus enable practical diagnostics reconstructions such as medical diagnosis, spray analysis, and atmosphere sciences.

  8. Preliminary assessment of atmospheric turbidity at Dhahran, Saudi Arabia

    NASA Astrophysics Data System (ADS)

    Abdelrahman, M. A.; Nimmo, B. G.

    Spectral beam solar radiation measurements for the period July 1980 to June 1981 were made in Dhahran, Saudi Arabia (Lat. 26° 23', Long. 50° 00'), using broad-band niter techniques. Schott filters (OG1, RG2 and R08) arranged on an automatically rotated disk mounted on an Eppley Normal Incidence Pyrhcliometer were used for the measurements. The Beer-Lambert relation was used to calculate optical depths from which values of the Angström Coefficient of Turbidity, β, were obtained for the wavelength exponent, α = 1.3. In addition, Herovanu's method was used to obtain α and β values for each month. The 12-month average values of β and α were 0.22 and 1.28, respectively.

  9. Ultra-high spectral extinction Brillouin spectroscopy for turbid tissue measurements (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Zhang, Jitao; Fiore, Antonio; Shao, Peng; Yun, Seok-Hyun; Scarcelli, Giuliano

    2016-03-01

    Brillouin spectroscopy allows non-invasive measurement of the mechanical properties of a sample by measuring the spectra of acoustically induced light scattering therein, and thus has been widely investigated for biomedical application. Recently, the development of fast Brillouin spectrometry based on virtually-imaged phased array (VIPA) has made in-situ measurement of biomedical sample possible. However, one limitation of current Brillouin technique is the low spectral extinction, which limits the measurement to nearly transparent sample. In order to measure turbid sample, multistage VIPA can be cascaded to gain spectral extinction. For example, spectral extinction of ~80 dB was achieved using three-stage VIPA; however, this approach significantly sacrificed measurement throughput. In this work, we develop a novel spectrometer that achieves high extinction without significant signal loss. To achieve this goal, we combine a two-stage VIPA spectrometer with a triple-pass Fabry-Perot interferometer. The triple-pass Fabry-Perot interferometer acts as a band-pass filter with ~3 GHz bandwidth and ~35-dB spectral extinction. Therefore, the overall extinction of this spectrometer greatly surpasses 80 dB with only ~20% excess loss. We demonstrated the performance of this spectrometer measuring background-free Brillouin spectra from Intralipid solutions and within chicken tissue.

  10. Determination of struvite crystallization mechanisms in urine using turbidity measurement.

    PubMed

    Triger, Aurélien; Pic, Jean-Stéphane; Cabassud, Corinne

    2012-11-15

    Sanitation improvement in developing countries could be achieved through wastewater treatment processes. Nowadays alternative concepts such as urine separate collection are being developed. These processes would be an efficient way to reduce pollution of wastewater while recovering nutrients, especially phosphorus, which are lost in current wastewater treatment methods. The precipitation of struvite (MgNH(4)PO(4)∙6H(2)O) from urine is an efficient process yielding more than 98% phosphorus recovery with very high reaction rates. The work presented here aims to determine the kinetics and mechanisms of struvite precipitation in order to supply data for the design of efficient urine treatment processes. A methodology coupling the resolution of the population balance equation to turbidity measurement was developed, and batch experiments with synthetic and real urine were performed. The main mechanisms of struvite crystallization were identified as crystal growth and nucleation. A satisfactory approximation of the volumetric crystal size distribution was obtained. The study has shown the low influence on the crystallization process of natural organic matter contained in real urine. It has also highlighted the impact of operational parameters. Mixing conditions can create segregation and attrition which influence the nucleation rate, resulting in a change in crystals number, size, and thus final crystal size distribution (CSD). Moreover urine storage conditions can impact urea hydrolysis and lead to spontaneous struvite precipitation in the stock solution also influencing the final CSD. A few limits of the applied methodology and of the proposed modelling, due to these phenomena and to the turbidity measurement, are also discussed.

  11. Corals persisting in naturally turbid waters adjacent to a pristine catchment in Solomon Islands.

    PubMed

    Albert, Simon; Fisher, Paul L; Gibbes, Badin; Grinham, Alistair

    2015-05-15

    Few water quality measurements exist from pristine environments, with fewer reported studies of coastal water quality from Solomon Islands. Water quality benchmarks for the Solomons have relied on data from other geographic regions, often from quite different higher latitude developed nations, with large land masses. We present the first data of inshore turbidity and sedimentation rate for a pristine catchment on Isabel Island. Surveys recorded relatively high coral cover. The lowest cover was recorded at 22.7% (Jejevo) despite this site having a mean turbidity (continuous monitoring) of 32 NTU. However, a similar site (Jihro) was significantly less turbid (2.1 mean NTU) over the same period. This difference in turbidity is likely due to natural features of the Jihro River promoting sedimentation before reaching coastal sites. We provide an important baseline for Solomon Island inshore systems, whilst demonstrating the importance of continuous monitoring to capture episodic high turbidity events.

  12. A drifter for measuring water turbidity in rivers and coastal oceans.

    PubMed

    Marchant, Ross; Reading, Dean; Ridd, James; Campbell, Sean; Ridd, Peter

    2015-02-15

    A disposable instrument for measuring water turbidity in rivers and coastal oceans is described. It transmits turbidity measurements and position data via a satellite uplink to a processing server. The primary purpose of the instrument is to help document changes in sediment runoff from river catchments in North Queensland, Australia. The 'river drifter' is released into a flooded river and drifts downstream to the ocean, measuring turbidity at regular intervals. Deployment in the Herbert River showed a downstream increase in turbidity, and thus suspended sediment concentration, while for the Johnstone River there was a rapid reduction in turbidity where the river entered the sea. Potential stranding along river banks is a limitation of the instrument. However, it has proved possible for drifters to routinely collect data along 80 km of the Herbert River. One drifter deployed in the Fly River, Papua New Guinea, travelled almost 200 km before stranding.

  13. Robust sensor for turbidity measurement from light scattering and absorbing liquids.

    PubMed

    Kontturi, Ville; Turunen, Petri; Uozumi, Jun; Peiponen, Kai-Erik

    2009-12-01

    Internationally standardized turbidity measurements for probing solid particles in liquid are problematic in the case of simultaneous light scattering and absorption. A method and a sensor to determine the turbidity in the presence of light absorption are presented. The developed sensor makes use of the total internal reflection of a laser beam at the liquid-prism interface, and the turbidity is assessed using the concept of laser speckle pattern. Using average filtering in speckle data analyzing the observed dynamic speckle pattern, which is due to light scattering from particles and the static speckle due to stray light of the sensor, can be separated from each other. Good correlation between the standard deviation of dynamic speckle and turbidity value for nonabsorbing and for absorbing liquids was observed. The sensor is suggested, for instance, for the measurement of ill-behaved as well as small-volume turbid liquids in both medicine and process industry.

  14. The Risk Analysis of Reservoir Water Supply under High Turbidity- Case Study of the Shihmen Reservoir

    NASA Astrophysics Data System (ADS)

    Chang, Y.; Chang, L.; Ko, S.; Ho, C.; Chen, Y.

    2010-12-01

    Due to the unstable geological condition of the Shihmen reservoir basin, the high turbidity of the outflow of water from the basin to the reservoir during typhoons causes rapid increase of turbidity in reservoir water. Because high water turbidity reduces the capacity of water treatment plants, water shortages could occur more frequently during typhoons and flood seasons. Based on the scenario described above, this study used the Monte Carlo analysis to evaluate shortage of water in the Taoyuan area when the Shihmen reservoir water was under conditions of high turbidity. The risk analysis process consisted of four sub-models: sub-model of rainfall synthesis, sub-model of rainfall runoff, sub-model of prediction of turbidity, and sub-model of management of water allocation under conditions of high turbidity. Two methods of prediction of turbidity, the artificial neural network (ANN) method and the unit characteristic hydrograph method, were developed and compared. The unit characteristic hydrograph method was modified from the unit hydrograph method and represented the relationship of reservoir inflow or outflow to the turbidity of reservoir water according to the function of unit response. Results of comparison of the two-methods indicated that the unit characteristic hydrograph method was more stable than the ANN method and included physical concepts that were easily understandable. Risk analysis showed a 57% possibility of water shortage during typhoons. Risk of water shortage decreased to 34% when tolerance of water shortage increased by 5%. Results of the case study demonstrated the reliability of the proposed procedure for risk assessment and method of prediction of turbidity prediction method. These methods could be extended to other reservoirs that have problems of high turbidity problem to assess risk of water shortage.

  15. Bacteria and Turbidity Survey for Blue Mountain Lake, Arkansas, Spring and Summer, 1994

    USGS Publications Warehouse

    Lasker, A. Dwight

    1995-01-01

    Introduction Blue Mountain Lake darn is located at river mile 74.4 on the Petit Jean River in Logan and Yell Counties in west-central Arkansas (fig. 1). Drainage area above the darn is 488 square miles. Blue Mountain Lake is located between two national forests-the Ozark National Forest and the Ouachita National Forest. The primary purpose for Blue Mountain Lake is flood control, but the lake is used for a variety of recreational purposes. The U.S. Geological Survey (USGS) in cooperation with the U.s. Army Corps of Engineers, Little Rock District, conducted a bacterial and turbidity study of the Blue Mountain Lake Basin during the spring and suri1mer 1994. Samples were collected weekly at 11 locations within the lake basin from May through September 1994. Eight sampling sites were located on tributaries to the lake and three sampling sites were located on the lake with one of the sites located at a swim beach (fig. 2; table 1).

  16. Spectrophotometric determination of turbid optical parameters without using an integrating sphere.

    PubMed

    Liang, Xiaohui; Li, Meihua; Lu, Jun Q; Huang, Chuanwei; Feng, Yuanming; Sa, Yu; Ding, Junhua; Hu, Xin-Hua

    2016-03-10

    Spectrophotometric quantification of turbidity by multiple optical parameters has wide-ranging applications in material analysis and life sciences. A robust system design needs to combine hardware for precise measurement of light signals with software to accurately model measurement configuration and rapidly solve a sequence of challenging inverse problems. We have developed and validated a design approach and performed system validation based on radiative transfer theory for determination of absorption coefficient, scattering coefficient, and anisotropy factor without using an integrating sphere. Accurate and rapid determination of parameters and spectra is achieved for microsphere suspension samples by combining photodiode-based measurement of four signals with the Monte Carlo simulation and perturbation-based inverse calculations. The three parameters of microsphere suspension samples have been determined from the measured signals as functions of wavelength from 400 to 800 nm and agree with calculated results based on the Mie theory. It has been shown that the inverse problems in the cases of microsphere suspension samples are well posed with convex cost functions to yield unique solutions, and it takes about 1 min to obtain the three parameters per wavelength.

  17. Determination of trace sulfides in turbid waters by gas dialysis/ion chromatography

    SciTech Connect

    Goodwin, L.R.; Francom, D.; Urso, A.; Dieken, F.P.

    1988-02-01

    The accuracy of the methylene blue colorimetric procedure for the determination of sulfide in environmental waters and waste waters is influenced by turbidity interferences even after application of recommended pretreatment techniques. The direct analysis of sulfide by ion chromatography (IC), without sample pretreatment, is complicated by field preservation of samples with zinc ion (or equivalent). A continuous-flow procedure has been developed that converts the acid-extractable sulfide to H/sub 2/S, which is separated from the sample matrix by a gas dialysis membrane and then trapped in a dilute sodium hydroxide solution. A 200-..mu..L portion of this solution is injected into the ion chromatograph for analysis with an electrochemical detector. Detection limits as low as 1.9 ng/mL have been obtained. Good agreement was found between the gas dialysis/IC and methylene blue methods for nonturbid standards. The addition of ascorbic acid as an antioxidant is required to obtain adequate recoveries from spiked tap and well waters.

  18. On-Line Analyzer For Monitoring Trace Amounts Of Oil In Turbid Waters

    NASA Astrophysics Data System (ADS)

    Niemela, P.; Jaatinen, J.

    1986-05-01

    This report presents an automated analyzer which continuously monitors oil content of a sample water stream that flows through the analyzer. The measuring principle is based on the absorption of infrared radiation by oil molecules contained in the sample water. The wavelength band that is used in the measurement is at 3.4 μm, where different types of oils show nearly equal absorption. Another wavelength band of 3.6 μm, where oil has no absorption, is used to compensate the effect of turbidity, which is due to solid particles and oil droplets contained in the sample water. Before entering the analyzer the sample water flow is properly homogenized. To compensate the strong absorption by water molecules in these wavelength bands the sample water is compared with reference water. This is done by directing them alternately through the same measuring cell. The reference water is obtained from the sample water by ultrafiltration and it determines the base line for the contaminated sample water. To ensure the stability of the base line, temperature and pressure differences of the two waters are kept within adequate ranges. Areas of application of the analyzer are wide ranging i.a. from ships' discharge waters to waste waters of industrial processes. The first application of the analyzer is on board oil tankers to control the discharge process of bilge and ballast waters. The analyzer is the first that fully corresponds to the stringent regulations for oil content monitors by the International Maritime Organization (IMO). Pilot installations of the analyzer are made on industrial plants.

  19. Photoacclimation supports environmental tolerance of a sponge to turbid low-light conditions

    NASA Astrophysics Data System (ADS)

    Biggerstaff, A.; Smith, D. J.; Jompa, J.; Bell, J. J.

    2015-12-01

    Changes to coral reefs are occurring worldwide, often resulting in declining environmental quality which can be in the form of higher sedimentation rates and increased turbidity. While environmental acclimation to turbid and low-light conditions has been extensively studied in corals, far less is known about other phototrophic reef invertebrates. The photosynthetic cyanobacteria containing sponge Lamellodysidea herbacea is one of the most abundant sponges in the Wakatobi Marine National Park (WMNP, Indonesia), and its abundance is greatest at highly disturbed, turbid sites. This study investigated photoacclimation of L. herbacea symbionts to turbid reef sites using in situ PAM fluorometry combined with shading and transplant experiments at environmental extremes of light availability for this species. We found in situ photoacclimation of L. herbacea to both shallow, clear, high-light environments and deep, turbid, low-light environments. Shading experiments provide some evidence that L. herbacea are dependent on nutrition from their photosymbionts as significant tissue loss was seen in shaded sponges. Symbionts within surviving shaded tissue showed evidence of photoacclimation. Lamellodysidea herbacea transplanted from high- to low-light conditions appeared to have photoacclimated within 5 d with no significant effect of the lowered light level on survival. This ability of L. herbacea to photoacclimate to rapid and extreme changes in light availability may be one of the factors contributing to their survival on more turbid reef sites in the WMNP. Our study highlights the ability of some sponge species to acclimate to changes in light levels as a result of increased turbidity.

  20. Spatial and temporal variations in high turbidity surface water off the Thule region, northwestern Greenland

    NASA Astrophysics Data System (ADS)

    Ohashi, Yoshihiko; Iida, Takahiro; Sugiyama, Shin; Aoki, Shigeru

    2016-09-01

    Glacial meltwater discharge from the Greenland ice sheet and ice caps forms high turbidity water in the proglacial ocean off the Greenland coast. Although the timing and magnitude of high turbidity water export affect the coastal marine environment, for example, through impacts on biological productivity, little is known about the characteristics of this high turbidity water. In this paper, we therefore report on the spatial and temporal variations in high turbidity water off the Thule region in northwestern Greenland, based on remote sensing reflectance data at a wavelength of 555 nm (Rrs555). The high turbidity area, identified on the basis of high reflectivity (Rrs555 ≥ 0.0070 sr-1), was generally distributed near the coast, where many outlet glaciers terminate in the ocean and on land. The extent of the high turbidity area exhibited substantial seasonal and interannual variability, and its annual maximum extent was significantly correlated with summer air temperature. Assuming a linear relationship between the high turbidity area and summer temperature, annual maximum extent increases under the influence of increasing glacial meltwater discharge, as can be inferred from present and predicted future warming trends.

  1. An alternative cost-effective image processing based sensor for continuous turbidity monitoring

    NASA Astrophysics Data System (ADS)

    Chai, Matthew Min Enn; Ng, Sing Muk; Chua, Hong Siang

    2017-03-01

    Turbidity is the degree to which the optical clarity of water is reduced by impurities in the water. High turbidity values in rivers and lakes promote the growth of pathogen, reduce dissolved oxygen levels and reduce light penetration. The conventional ways of on-site turbidity measurements involve the use of optical sensors similar to those used in commercial turbidimeters. However, these instruments require frequent maintenance due to biological fouling on the sensors. Thus, image processing was proposed as an alternative technique for continuous turbidity measurement to reduce frequency of maintenance. The camera was kept out of water to avoid biofouling while other parts of the system submerged in water can be coated with anti-fouling surface. The setup developed consisting of a webcam, a light source, a microprocessor and a motor used to control the depth of a reference object. The image processing algorithm quantifies the relationship between the number of circles detected on the reference object and the depth of the reference object. By relating the quantified data to turbidity, the setup was able to detect turbidity levels from 20 NTU to 380 NTU with measurement error of 15.7 percent. The repeatability and sensitivity of the turbidity measurement was found to be satisfactory.

  2. Effects of suspended sediment concentration and grain size on three optical turbidity sensors

    USGS Publications Warehouse

    Merten, Gustavo Henrique; Capel, Paul D.; Minella, Jean P.G.

    2014-01-01

    Purpose: Optical turbidity sensors have been successfully used to determine suspended sediment flux in rivers, assuming the relation between the turbidity signal and suspended sediment concentration (SSC) has been appropriately calibrated. Sediment size, shape and colour affect turbidity and are important to incorporate into the calibration process. Materials and methods: This study evaluates the effect of SSC and particle size (i.e. medium sand, fine sand, very fine sand, and fines (silt + clay)) on the sensitivity of the turbidity signal. Three different turbidity sensors were used, with photo detectors positioned at 90 and 180 degrees relative to the axis of incident light. Five different sediment ratios of sand:fines (0:100, 25:75, 50:50, 75:25 and 100:0) were also evaluated for a single SSC (1000 mg l-1). Results and discussion: The photo detectors positioned at 90 degrees were more sensitive than sensor positioned at 180 degrees in reading a wide variety of grain size particles. On average for the three turbidity sensors, the sensitivity for fines were 170, 40, and 4 times greater than sensitivities for medium sand, fine sand, and very fine sand, respectively. For an SSC of 1000 mg l-1 with the treatments composed of different proportions of sand and fines, the presence of sand in the mixture linearly reduced the turbidity signal. Conclusions: The results indicate that calibration of the turbidity signal should be carried out in situ and that the attenuation of the turbidity signal due to sand can be corrected, as long as the proportion of sand in the SSC can be estimated.

  3. Drinking water turbidity and emergency department visits for gastrointestinal illness in Atlanta, 1993-2004.

    PubMed

    Tinker, Sarah C; Moe, Christine L; Klein, Mitchel; Flanders, W Dana; Uber, Jim; Amirtharajah, Appiah; Singer, Philip; Tolbert, Paige E

    2010-01-01

    The extent to which drinking water turbidity measurements indicate the risk of gastrointestinal illness is not well understood. Despite major advances in drinking water treatment and delivery, infectious disease can still be transmitted through drinking water in the United States, and it is important to have reliable indicators of microbial water quality to inform public health decisions. The objective of our study was to assess the relationship between gastrointestinal illness, quantified through emergency department visits, and drinking water quality, quantified as raw water and filtered water turbidity measured at the treatment plant. We examined the relationship between turbidity levels of raw and filtered surface water measured at eight major drinking water treatment plants in the metropolitan area of Atlanta, Georgia, and over 240,000 emergency department visits for gastrointestinal illness during 1993-2004 among the population served by these plants. We fit Poisson time-series statistical regression models that included turbidity in a 21-day distributed lag and that controlled for meteorological factors and long-term time trends. For filtered water turbidity, the results were consistent with no association with emergency department visits for gastrointestinal illness. We observed a modest association between raw water turbidity and emergency department visits for gastrointestinal illness. Our results suggest that source water quality may contribute modestly to endemic gastrointestinal illness in the study area. The association between turbidity and emergency department visits for gastrointestinal illness was only observed when raw water turbidity was considered; filtered water turbidity may not serve as a reliable indicator of modest pathogen risk at all treatment plants.

  4. Modeling seasonal and interannual variability in atmospheric turbidity with application to South Africa

    NASA Astrophysics Data System (ADS)

    Power, Helen Claire

    1999-12-01

    Aerosols have several important influences on the climate system. Among the more important of these are their roles in absorbing and scattering radiation, and as condensation nuclei in cloud-forming processes. Despite their importance, our knowledge of their spatial and temporal variability and, in turn, their influence on climate, is incomplete. This research presents a methodology for estimating and examining atmospheric turbidity, a convenient surrogate for the amount of aerosols in the atmospheric column. Constraints associated with conventional approaches to measuring turbidity-including the requirements for clear skies and costly equipment-have contributed to the paucity of turbidity data. This is especially true for the Southern Hemisphere. My research refines and applies techniques for estimating monthly turbidity from readily available surface-weather data, regardless of cloud cover. Using a high-resolution spectral radiation model, clear-sky beam irradiance is parameterized as a function of atmospheric attenuation processes, including scattering and absorption by aerosols. This model is then integrated over the day to obtain an expression for estimating potential daily clear-sky beam irradiation. By forcing the model with monthly-averaged climate data, turbidity is estimated at an array of eight weather-station locations in South Africa. Findings include new estimates of turbidity trends and variability over South Africa. Seasonal trends are evident at many stations although there is no consistent trend. Over recent decades, turbidity has generally been stable at six of the eight stations. In Cape Town, there has been an increase in turbidity over the last 30 years, while in Grootfontein turbidity appears to have decreased over the 25-year record. The methodology can be applied at any location where the requisite climate data are available and therefore holds promise for a more complete, and possibly global, climatology of aerosols.

  5. Determination of soluble immunoglobulin G in bovine colostrum products by Protein G affinity chromatography-turbidity correction and method validation.

    PubMed

    Holland, Patrick T; Cargill, Anne; Selwood, Andrew I; Arnold, Kate; Krammer, Jacqueline L; Pearce, Kevin N

    2011-05-25

    Immunoglobulin-containing food products and nutraceuticals such as bovine colostrum are of interest to consumers as they may provide health benefits. Commercial scale colostrum products are valued for their immunoglobulin G (IgG) content and therefore require accurate analysis. One of the most commonly used methods for determining total soluble IgG in colostrum products is based on affinity chromatography using a Protein G column and UV detection. This paper documents improvements to the accuracy of the Protein G analysis of IgG in colostrum products, especially those containing aggregated forms of IgG. Capillary electrophoresis-sodium dodecyl sulfate (CE-SDS) analysis confirmed that aggregated IgG measured by Protein G does not contain significant amounts of casein or other milk proteins. Size exclusion chromatography identified the content of soluble IgG as mainly monomeric IgG and aggregated material MW > 450 kDa with small amounts of dimer and trimer. The turbidity of the eluting IgG, mainly associated with aggregated IgG, had a significant effect on the quantitative results. Practical techniques were developed to correct affinity LC data for turbidity on an accurate, consistent, and efficient basis. The method was validated in two laboratories using a variety of colostrum powders. Precision for IgG was 2-3% (RSD(r)) and 3-12% (RSD(R)). Recovery was 100.2 ± 2.4% (mean ± RSD, n = 10). Greater amounts of aggregated IgG were solubilized by a higher solution:sample ratio and extended times of mixing or sonication, especially for freeze-dried material. It is concluded that the method without acid precipitation and with turbidity correction provides accurate, precise, and robust data for total soluble IgG and is suitable for product specification and quality control of colostrum products.

  6. Fluvial suspended sediment characteristics by high-resolution, surrogate metrics of turbidity, laser-diffraction, acoustic backscatter, and acoustic attenuation

    NASA Astrophysics Data System (ADS)

    Landers, Mark Newton

    Sedimentation is a primary and growing environmental, engineering, and agricultural issue around the world. However, collection of the data needed to develop solutions to sedimentation issues has declined by about three-fourths since 1983. Suspended-sediment surrogates have the potential to obtain sediment data using methods that are more accurate, of higher spatial and temporal resolution, and with less manually intensive, costly, and hazardous methods. The improved quality of sediment data from high-resolution surrogates may inform improved understanding and solutions to sedimentation problems. The field experiments for this research include physical samples of suspended sediment collected concurrently with surrogate metrics from instruments including 1.2, 1.5, and 3.0 megahertz frequency acoustic doppler current profilers, a nephelometric turbidity sensor, and a laser-diffraction particle size analyzer. This comprehensive data set was collected over five storms in 2009 and 2010 at Yellow River near Atlanta, Georgia. Fluvial suspended sediment characteristics in this study can be determined by high-resolution surrogate parameters of turbidity, laser-diffraction and acoustics with model errors 33% to 49% lower than traditional methods using streamflow alone. Hysteresis in sediment-turbidity relations for single storm events was observed and quantitatively related to PSD changes of less than 10 microns in the fine silt to clay size range. Suspended sediment particle size detection (PSD) is significantly correlated with ratios of measured acoustic attenuation at different frequencies; however the data do not fit the theoretical relations. Using both relative acoustic backscatter (RB) and acoustic attenuation as explanatory variables results in a significantly improved model of suspended sediment compared with traditional sonar equations using only RB. High resolution PSD data from laser diffraction provide uniquely valuable information; however the size detection

  7. Extension of the Stokes equation for layered constructions to fluorescent turbid media.

    PubMed

    Coppel, Ludovic G; Neuman, Magnus; Edström, Per

    2012-04-01

    Expressions relating the bispectral reflectance of a stack of n fluorescing layers to each individual layer's reflectance and transmittance are derived. This theoretical framework is used together with recently proposed extensions of the Kubelka-Munk model to study the fluorescence from layered turbid media. For one layer over a reflecting background, the model is shown to give the same results as a previous model. The extension to n layers with different optical properties allows simulating the bispectral reflectance from a pad of layered turbid media. The applicability of the model is exemplified with an optimization of fluorophore distribution in layered turbid media.

  8. Can turbidity caused by Corophium volutator (Pallas) activity be used to assess sediment toxicity rapidly?

    PubMed

    Briggs, Andrew D; Greenwood, Naomi; Grant, Alastair

    2003-04-01

    The standard toxicity test organism, Corophium volutator, exhibits a behavioural response to contaminated sediments that causes increased turbidity of overlying water. We quantify the effects of this response to an estuarine sediment spiked with copper and hydrocarbon contaminated sediments from an oil installation in the North Sea. Turbidity measured 24 h after the start of a toxicity test shows a strong relationship with contaminant concentrations and with mortality after 10 days. Turbidity measurements can therefore give a rapid indication of sediment toxicity, permitting a reduction in storage time of sediments to be used in dilution series and toxicity identification evaluation (TIE) tests, reducing the likelihood of contaminants degrading prior to testing.

  9. The influence of turbid medium properties on object visibility in optical Kerr gated imaging

    NASA Astrophysics Data System (ADS)

    Zhan, Pingping; Si, Jinhai; Tan, Wenjiang; Liu, Xin; Wu, Bin; Xu, Shichao; Chen, Feng; Hou, Xun

    2014-01-01

    In this paper, we demonstrate femtosecond optical Kerr gated imaging of an object hidden behind a highly turbid medium. The influence of turbid medium properties on image contrast has been investigated. Experimental and Monte Carlo simulation results show that for a given optical density, the image contrast of direct imaging without an optical Kerr gate decreases with the increase of the scattering particle size or the decrease of the thickness of the turbid medium. Compared with direct imaging, optical Kerr gated imaging has a better image contrast as it eliminates more scattered photons effectively. Qualitative comparisons between experiments and simulations show good agreement.

  10. Bioremediation of Turbid Surface Water Using Seed Extract from the Moringa oleifera Lam. (Drumstick) Tree.

    PubMed

    Lea, Michael

    2014-05-01

    An indigenous water treatment method uses Moringa oleifera seeds in the form of a crude water-soluble extract in suspension, resulting in an effective natural clarification agent for highly turbid and untreated pathogenic surface water. Efficient reduction (80.0% to 99.5%) of high turbidity produces an aesthetically clear supernatant, concurrently accompanied by 90.00% to 99.99% (1 to 4 log) bacterial reduction. Application of this low-cost Moringa oleifera protocol is recommended for water treatment where rural and peri-urban people living in extreme poverty are presently drinking highly turbid and microbiologically contaminated water.

  11. Bioremediation of turbid surface water using seed extract from Moringa oleifera Lam. (drumstick) tree.

    PubMed

    Lea, Michael

    2010-02-01

    An indigenous water treatment method uses Moringa oleifera seeds in the form of a water-soluble extract in suspension, resulting in an effective natural clarification agent for highly turbid and untreated pathogenic surface water. Efficient reduction (80.0% to 99.5%) of high turbidity produces an aesthetically clear supernatant, concurrently accompanied by 90.00% to 99.99% (1 to 4 log) bacterial reduction. Application of this low-cost Moringa oleifera protocol is recommended for simplified, point-of-use, low-risk water treatment where rural and peri-urban people living in extreme poverty are presently drinking highly turbid and microbiologically contaminated water.

  12. Beyond Rating Curves: Time Series Models for in-Stream Turbidity Prediction

    NASA Astrophysics Data System (ADS)

    Wang, L.; Mukundan, R.; Zion, M.; Pierson, D. C.

    2012-12-01

    The New York City Department of Environmental Protection (DEP) manages New York City's water supply, which is comprised of over 20 reservoirs and supplies over 1 billion gallons of water per day to more than 9 million customers. DEP's "West of Hudson" reservoirs located in the Catskill Mountains are unfiltered per a renewable filtration avoidance determination granted by the EPA. While water quality is usually pristine, high volume storm events occasionally cause the reservoirs to become highly turbid. A logical strategy for turbidity control is to temporarily remove the turbid reservoirs from service. While effective in limiting delivery of turbid water and reducing the need for in-reservoir alum flocculation, this strategy runs the risk of negatively impacting water supply reliability. Thus, it is advantageous for DEP to understand how long a particular turbidity event will affect their system. In order to understand the duration, intensity and total load of a turbidity event, predictions of future in-stream turbidity values are important. Traditionally, turbidity predictions have been carried out by applying streamflow observations/forecasts to a flow-turbidity rating curve. However, predictions from rating curves are often inaccurate due to inter- and intra-event variability in flow-turbidity relationships. Predictions can be improved by applying an autoregressive moving average (ARMA) time series model in combination with a traditional rating curve. Since 2003, DEP and the Upstate Freshwater Institute have compiled a relatively consistent set of 15-minute turbidity observations at various locations on Esopus Creek above Ashokan Reservoir. Using daily averages of this data and streamflow observations at nearby USGS gauges, flow-turbidity rating curves were developed via linear regression. Time series analysis revealed that the linear regression residuals may be represented using an ARMA(1,2) process. Based on this information, flow-turbidity regressions with

  13. Time-to-turbidity model for non-protective type B Clostridium botulinum.

    PubMed

    Whiting, R C; Oriente, J C

    1997-04-29

    A model to predict the time for growth to turbidity from spores of non-proteolytic type B strains of Clostridium botulinum was developed in broth media with varying temperatures (4-28 degrees C), pH values (5-7), NaCl additions (0-4%) and total spores (10(1)-10(5)). The model estimates the probability that a sample will have growth on a given day for up to 90 days of storage. The parameters of the model include the probability of growth after 90 days (Pmax) and the mean time of growth (tau) for those that showed growth. The 95% confidence interval (CI95%) for tau was also determined. The tau decreased with increasing temperature and pH, but NaCl levels below 3% had little effect. Decreasing the number of spores in a sample increased both tau and the confidence intervals about tau, reflecting the increasing uncertainty about the estimation of growth times for low spore numbers.

  14. Evaluation of optical coherence quantitation of analytes in turbid media by use of two wavelengths

    SciTech Connect

    Sathyam, U.S.; Colston, B.W. Jr.; Da Silva, L.B.; Everett, M.J.

    1999-04-01

    We introduce a novel method for determining analyte concentration as a function of depth in a highly scattering media by use of a dual-wavelength optical coherence tomography system. We account for the effect of scattering on the measured attenuation by using a second wavelength that is not absorbed by the sample. We assess the applicability of this technique by measuring the concentration of water in an Intralipid phantom, using a probe wavelength of 1.53 {mu}m and a reference wavelength of 1.31 {mu}m. The results of our study show a strong correlation between the measured absorption and the water content of the sample. The accuracy of the technique, however, was limited by the dominance of scattering over absorption in the turbid media. Thus, although the effects of scattering were minimized, significant errors remained in the calculated absorption values. More-accurate results could be obtained with the use of more powerful superluminescent diodes and a choice of wavelengths at which absorption effects are more significant relative to scattering. {copyright} 1999 Optical Society of America

  15. Extraction of effective parameters of turbid media utilizing the Mueller matrix approach: study of glucose sensing.

    PubMed

    Pham, Thi-Thu-Hien; Lo, Yu-Lung

    2012-09-01

    An analytical technique based on Stokes polarimetry and the Mueller matrix method is proposed for extracting the effective linear birefringence, linear dichroism, circular birefringence, circular dichroism, linear depolarization, and circular depolarization properties of turbid media. In contrast to existing analytical models, the model proposed extracts the effective parameters in a decoupled manner and considers not only the circular dichroism properties of the sample, but also the depolarization properties. The results show that the proposed method enables all of the effective parameters to be measured over the full range. Moreover, it is shown that the extracted value of the depolarization index is unaffected by the order in which the depolarizing Mueller matrix is decomposed during the extraction procedure. Finally, a method is proposed for calibrating the optical rotation angle of a polystyrene microsphere suspension containing dissolved D-glucose (C6H12O6) powder in accordance with the distance between the sample and the detector. The experimental results show that the sensitivity of the resulting D-glucose measurement is equal to approximately 1.73  deg/M.

  16. Population structure and residency patterns of the blacktip reef shark Carcharhinus melanopterus in turbid coastal environments.

    PubMed

    Chin, A; Tobin, A J; Heupel, M R; Simpfendorfer, C A

    2013-04-01

    This study examined the characteristics of a blacktip reef shark Carcharhinus melanopterus population in turbid coastal habitats through a multi-year fishery-independent sampling and tag-recapture programme. Results revealed a highly structured population comprised almost entirely of juveniles and adult females with individuals between 850 and 1050 mm total length effectively absent. Mature males were also rarely encountered with adult sex ratio highly biased towards females (female:male = 7:1). Mating scars were observed on adult females between December and April, and parturition was observed from December to March. Regression analysis showed that catch rates were significantly higher during the summer wet season between November and May. Recapture data suggested a highly resident population with a recapture rate of 21% and a mean recapture distance of 0·8 km. In addition, 33% of recaptured animals were captured multiple times, indicating long-term residency. Most recaptures were, however, of adults with few juveniles recaptured. Widespread sampling at the study site and in adjacent areas suggested that the population was highly localized to a specific bay. The bimodal and sex-segregated population structure observed here differs from previous reports for this species, and in combination with reproductive observations, suggests population structuring to facilitate reproductive and recruitment success. These data also highlight the potential ecosystem functions performed by coastal habitats in sustaining C. melanopterus populations.

  17. Turbid medium polarimetry in biomedical imaging and diagnosis

    NASA Astrophysics Data System (ADS)

    Ghosh, N.; Banerjee, A.; Soni, J.

    2011-06-01

    Studies on polarization properties of scattered light from a random medium like biological tissue have received considerable attention because polarization can be used as an effective tool to discriminate against multiply scattered light (acting as a gating mechanism) and thus can facilitate high resolution imaging through tissue. Further, the polarization properties of scattered light from tissue contain wealth of morphological and functional information of potential biomedical importance. However, in a complex random medium like tissue, numerous complexities due to multiple scattering and simultaneous occurrences of many scattering and polarization events present formidable challenges both in terms of accurate measurements and in terms of analysis of the tissue polarimetry signal. Several studies have therefore been conducted in the recent past to develop appropriate measurement procedures, suitable light propagation models and polarimetry signal analysis methods to overcome these difficulties. In this review, we focus on some of the recent key developments in this area. Specifically, we describe variety of theoretical and experimental tools, illustrated with selected results, aimed at evaluating the prospect of turbid medium polarimetry for both biomedical imaging and diagnosis.

  18. Study of inhomogeneities in turbid media: experimental and numerical results

    NASA Astrophysics Data System (ADS)

    Carbone, N. A.; di Rocco, Héctor O.; Iriarte, Daniela I.; Pomarico, Juan A.; Ranea-Sandoval, Héctor F.; Pardini, Pamela; Waks-Serra, M. Victoria

    2011-08-01

    Near Infrared diffuse transmission of light through tissue is a tool for noninvasive imaging for diagnostic purposes. Most of the research has been focused over breast cancer imaging; however, major efforts have been done in cerebral tomography and topography imaging, as well as small animal organs imaging systems. In this work, we investigate the transmitted light profiles when scattering and absorbing cylindrical inhomogeneities are submerged at different depths inside slabs of turbid media. We analyze the transilluminance profiles when the phantom is scanned using both, CW and time resolved detection. The study of the spatial profiles obtained with CW light, shows an apparently contradictory effect when the absorption coefficient of the inclusion is higher than that of the bulk. In this case, the intensity profiles displays a peak of higher intensity where the inclusion is located, as it would be expected for a less absorbing inclusion. The experiments were compared and analyzed with a theoretical model for cylindrical inclusions and Monte Carlo simulations implemented in a Graphic Processing Unit (GPU).

  19. Hyperspectral simulation and recovery of submerged targets in turbid waters

    NASA Astrophysics Data System (ADS)

    Bostater, Charles R., Jr.

    2005-05-01

    Modeled hyperspectral reflectance signatures just above the water surface are obtained from radiative transfer models to create synthetic images of targets below the water surface. Images are displayed as 24 bit RGB images of the water surface using selected channels. Example model outputs are presented in this paper for a hyperspectral Monte Carlo and a hyperspectral layered analytical iterative model of radiative transport within turbid shallow water types. Images at the selected wavelengths or channels centered at 490, 530 and 680 nm suggests the two models provide quite similar results when displayed as RGB images. The techniques are demonstrated to the problem of extracting synthetic targets from hyperspectral synthetic images in the presence of water surface wave, using spectral wave models. The most sensitive parameters for generating realistic images are water depth and bottom reflectance in clean natural and optically shallow waters. Also presented are platforms for use in ports, harbors, inlets and waterways developed and designed for current and future monitoring to insure sustainable safe shallow water environments.

  20. Optoacoustic signal profiles for monitoring glucose concentration in turbid media

    NASA Astrophysics Data System (ADS)

    Larin, Kirill V.; Oraevsky, Alexander A.

    1999-03-01

    Our research project is focused on theoretical and experimental studies into the possibility of in vivo monitoring of blood glucose concentration. Previous experiments demonstrated that the presence of glucose dissolved in aqueous solution of polystyrene microspheres increases the refractive index of this solution due to glucose hydrophilic properties. As a strong osmolyte glucose influences the scattering properties of any particles or fibers suspended in water or biological fluids. We measured profiles of absorbed laser energy distributions as a function of glucose concentration in aqueous solution of polystyrene microspheres colored with potassium chromate. Experiments were performed at the wavelength of the Nd:YAG laser third harmonic, (lambda) equals 355 nm. The results obtained demonstrated a 4.5% decrease in effective optical attenuation coefficient with a 100 mM increase in glucose concentration. These initial results demonstrated that the effect of glucose on optical attenuation of turbid aqueous solutions is small but reliably measurable with the use of the time-resolved optoacoustic technique.

  1. Controlled light field concentration through turbid biological membrane for phototherapy.

    PubMed

    Wang, Fujuan; He, Hexiang; Zhuang, Huichang; Xie, Xiangsheng; Yang, Zhenchong; Cai, Zhigang; Gu, Huaiyu; Zhou, Jianying

    2015-06-01

    Laser propagation through a turbid rat dura mater membrane is shown to be controllable with a wavefront modulation technique. The scattered light field can be refocused into a target area behind the rat dura mater membrane with a 110 times intensity enhancement using a spatial light modulator. The efficient laser intensity concentration system is demonstrated to imitate the phototherapy for human brain tumors. The power density in the target area is enhanced more than 200 times compared with the input power density on the dura mater membrane, thus allowing continued irradiation concentration to the deep lesion without damage to the dura mater. Multibeam inputs along different directions, or at different positions, can be guided to focus to the same spot behind the membrane, hence providing a similar gamma knife function in optical spectral range. Moreover, both the polarization and the phase of the input field can be recovered in the target area, allowing coherent field superposition in comparison with the linear intensity superposition for the gamma knife.

  2. Controlled light field concentration through turbid biological membrane for phototherapy

    PubMed Central

    Wang, Fujuan; He, Hexiang; Zhuang, Huichang; Xie, Xiangsheng; Yang, Zhenchong; Cai, Zhigang; Gu, Huaiyu; Zhou, Jianying

    2015-01-01

    Laser propagation through a turbid rat dura mater membrane is shown to be controllable with a wavefront modulation technique. The scattered light field can be refocused into a target area behind the rat dura mater membrane with a 110 times intensity enhancement using a spatial light modulator. The efficient laser intensity concentration system is demonstrated to imitate the phototherapy for human brain tumors. The power density in the target area is enhanced more than 200 times compared with the input power density on the dura mater membrane, thus allowing continued irradiation concentration to the deep lesion without damage to the dura mater. Multibeam inputs along different directions, or at different positions, can be guided to focus to the same spot behind the membrane, hence providing a similar gamma knife function in optical spectral range. Moreover, both the polarization and the phase of the input field can be recovered in the target area, allowing coherent field superposition in comparison with the linear intensity superposition for the gamma knife. PMID:26114042

  3. Escherichia coli bacteria density in relation to turbidity, streamflow characteristics, and season in the Chattahoochee River near Atlanta, Georgia, October 2000 through September 2008—Description, statistical analysis, and predictive modeling

    USGS Publications Warehouse

    Lawrence, Stephen J.

    2012-01-01

    Regression analyses show that E. coli density in samples was strongly related to turbidity, streamflow characteristics, and season at both sites. The regression equation chosen for the Norcross data showed that 78 percent of the variability in E. coli density (in log base 10 units) was explained by the variability in turbidity values (in log base 10 units), streamflow event (dry-weather flow or stormflow), season (cool or warm), and an interaction term that is the cross product of streamflow event and turbidity. The regression equation chosen for the Atlanta data showed that 76 percent of the variability in E. coli density (in log base 10 units) was explained by the variability in turbidity values (in log base 10 units), water temperature, streamflow event, and an interaction term that is the cross product of streamflow event and turbidity. Residual analysis and model confirmation using new data indicated the regression equations selected at both sites predicted E. coli density within the 90 percent prediction intervals of the equations and could be used to predict E. coli density in real time at both sites.

  4. The effect of submerged aquatic vegetation expansion on a declining turbidity trend in the Sacramento-San Joaquin River Delta

    USGS Publications Warehouse

    Hestir, E.L.; Schoellhamer, David H.; Jonathan Greenberg,; Morgan-King, Tara L.; Ustin, S.L.

    2016-01-01

    Submerged aquatic vegetation (SAV) has well-documented effects on water clarity. SAV beds can slow water movement and reduce bed shear stress, promoting sedimentation and reducing suspension. However, estuaries have multiple controls on turbidity that make it difficult to determine the effect of SAV on water clarity. In this study, we investigated the effect of primarily invasive SAV expansion on a concomitant decline in turbidity in the Sacramento-San Joaquin River Delta. The objective of this study was to separate the effects of decreasing sediment supply from the watershed from increasing SAV cover to determine the effect of SAV on the declining turbidity trend. SAV cover was determined by airborne hyperspectral remote sensing and turbidity data from long-term monitoring records. The turbidity trends were corrected for the declining sediment supply using suspended-sediment concentration data from a station immediately upstream of the Delta. We found a significant negative trend in turbidity from 1975 to 2008, and when we removed the sediment supply signal from the trend it was still significant and negative, indicating that a factor other than sediment supply was responsible for part of the turbidity decline. Turbidity monitoring stations with high rates of SAV expansion had steeper and more significant turbidity trends than those with low SAV cover. Our findings suggest that SAV is an important (but not sole) factor in the turbidity decline, and we estimate that 21–70 % of the total declining turbidity trend is due to SAV expansion.

  5. Field turbidity method for the determination of lead in acid extracts of dried paint.

    PubMed

    Studabaker, William B; McCombs, Michelle; Sorrell, Kristen; Salmons, Cynthia; Brown, G Gordon; Binstock, David; Gutknecht, William F; Harper, Sharon L

    2010-07-08

    Lead, which can be found in old paint, soil, and dust, has been clearly shown to have adverse health effects on the neurological systems of both children and adults. As part of an ongoing effort to reduce childhood lead poisoning, the US Environmental Protection Agency promulgated the Lead Renovation, Repair, and Painting Program (RRP) rule requiring that paint in target housing built prior to 1978 be tested for lead before any renovation, repair, or painting activities are initiated. This rule has led to a need for a rapid, relatively easy, and an inexpensive method for measuring lead in paint. This paper presents a new method for measuring lead extracted from paint that is based on turbidimetry. This method is applicable to paint that has been collected from a surface and extracted into 25% (v/v) of nitric acid. An aliquot of the filtered extract is mixed with an aliquot of solid potassium molybdate in 1 M ammonium acetate to form a turbid suspension of lead molybdate. The lead concentration is determined using a portable turbidity meter. This turbidimetric method has a response of approximately 0.9 NTU per microg lead per mL extract, with a range of 1-1000 Nephelometric Turbidity Units (NTUs). Precision at a concentration corresponding to the EPA-mandated decision point of 1 mg of lead per cm(2) is <2%. This method is insensitive to the presence of other metals common to paint, including Ba(2+), Ca(2+), Mg(2+), Fe(3+), Co(2+), Cu(2+), and Cd(2+), at concentrations of 10 mg mL(-1) or to Zn(2+) at 50 mg mL(-1). Analysis of 14 samples from six reference materials with lead concentrations near 1 mg cm(-2) yielded a correlation to inductively coupled plasma-atomic emission spectroscopy (ICP-AES) analysis of 0.97, with an average bias of 2.8%. Twenty-four sets of either 6 or 10 paint samples each were collected from different locations in old houses, a hospital, tobacco factory, and power station. Half of each set was analyzed using rotor/stator-25% (v/v) nitric acid

  6. Target detection in turbid medium using polarization-based range-gated technology.

    PubMed

    Guan, Jinge; Zhu, Jingping

    2013-06-17

    Range-gated technology is well known for its good reliability, large field of view (FOV) and low cost in target detection through scattering or turbid medium. However, the tail-gating technology suffers from low signal-to-noise ratio in high turbidity levels due to superposition of photons multiply scattered from the medium and that reflected from the target. In this paper, polarization properties of multiply scattered photons emerging from the turbid medium are studied. Results demonstrate that diffusive photons are almost completely depolarized with no diattenuation and retardance. We combined the tail-gated technology with polarization detection method to effectively image in high level of turbidity. This approach showed about two times enhancement in image contrast as compared with the conventional range-gated technology.

  7. Multiwavelength Photosensor for On-Chip Real-Time Monitoring of Fluorescence and Turbidity

    NASA Astrophysics Data System (ADS)

    Maruyama, Yuki; Ishida, Makoto; Sawada, Kazuaki

    2009-06-01

    In this paper, we report simultaneous detection of fluorescence and turbidity using a multiwavelength photosensor. The multiwavelength photosensor is fabricated in a 5 µm 1-poly 1-metal p-well complementary metal oxide semiconductor (CMOS) technology. First, to confirm the basic characteristics of the multiwavelength photosensor, the linearity of irradiated intensity and photocurrent, fluorescence detection capability, and turbidity detection capability were separately observed. Then, in the fluorescence detection measurement using a fluorescent dye, a detection limit of DNA concentration of 49.8 nM was determined. Then, the turbidity detection performance was compared with that of a Si photodiode. Finally, the sensor was used for real-time monitoring of DNA amplification using the loop-mediated isothermal amplification (LAMP) method. Owing to its multiwavelength detection, simultaneous changes in fluorescence and turbidity were successfully observed using a single sensor.

  8. Long-range sediment transport in the world's oceans by stably stratified turbidity currents

    NASA Astrophysics Data System (ADS)

    Kneller, Benjamin; Nasr-Azadani, Mohamad M.; Radhakrishnan, Senthil; Meiburg, Eckart

    2016-12-01

    Submarine fans, supplied primarily by turbidity currents, constitute the largest sediment accumulations on Earth. Generally accepted models of turbidity current behavior imply they should dissipate rapidly on the very small gradients of submarine fans, thus their persistence over long distances is enigmatic. We present numerical evidence, constrained by published field data, suggesting that turbidity currents traveling on low slopes and carrying fine particles have a stably stratified shear layer along their upper interface, which dramatically reduces dissipation and entrainment of ambient fluid, allowing the current to propagate over long distances. We propose gradient Richardson number as a useful criterion to discriminate between the different behaviors exhibited by turbidity currents on high and low slopes.

  9. Major Turbidity Events in the North Santiam River Basin, Oregon, Water Years 1999-2004

    USGS Publications Warehouse

    Sobieszczyk, Steven; Uhrich, Mark A.; Bragg, Heather M.

    2007-01-01

    Multiple high-turbidity events with values greater than 250 Formazin Nephelometric Units occurred in streams of the North Santiam River basin during water years 1999-2004. By using a combination of field reconnaissance, aerial photography, and geographic information systems, eight of these high-turbidity events were investigated and linked to at least one likely source area and became known as 'major turbidity events.' Sediment source type and location, the amount of material transported, and the results of any follow-up investigation of the source area were recorded for each event. Significant findings from this study include: * Although heavy precipitation caused basinwide erosion that increased turbidity in streams, a major turbidity event often required at least one landslide or similar type of contributing source to introduce enough sediment to raise the turbidity value to greater than 250 Formazin Nephelometric Units. * Different processes drove sediment loading at different times. In general, precipitation eroded sediment from source areas or induced landslides. However, in two cases, warm temperatures caused rapid snowmelt, which supplied the water necessary to erode unconsolidated glacial soils or other sediment material and increase turbidity. * Some source areas, such as existing earthflows, repeatedly supplied a large volume of sediment to streams, whereas other sources, such as landslides or debris flows, were unpredictable and sporadically supplied large volumes of sediment to streams. * Major turbidity events were well distributed throughout the North Santiam River basin; discrete events were observed in each of the five subbasins along unregulated streams. * Suspended-sediment loads and clay-water (persistently turbid water) volume estimates were event-specific and varied greatly between major turbidity events, even though, in some cases, the source area was the same; however, high yields generally were observed for events in the Blowout Creek

  10. Context-dependent planktivory: interacting effects of turbidity and predation risk on adaptive foraging

    USGS Publications Warehouse

    Pangle, Kevin L.; Malinich, Timothy D.; Bunnell, David B.; DeVries, Dennis R.; Ludsin, Stuart A.

    2012-01-01

    By shaping species interactions, adaptive phenotypic plasticity can profoundly influence ecosystems. Predicting such outcomes has proven difficult, however, owing in part to the dependence of plasticity on the environmental context. Of particular relevance are environmental factors that affect sensory performance in organisms in ways that alter the tradeoffs associated with adaptive phenotypic responses. We explored the influence of turbidity, which simultaneously and differentially affects the sensory performance of consumers at multiple trophic levels, on the indirect effect of a top predator (piscivorous fish) on a basal prey resource (zooplankton) that is mediated through changes in the plastic foraging behavior of an intermediate consumer (zooplanktivorous fish). We first generated theoretical predictions of the adaptive foraging response of a zooplanktivore across wide gradients of turbidity and predation risk by a piscivore. Our model predicted that predation risk can change the negative relationship between intermediate consumer foraging and turbidity into a humped-shaped (unimodal) one in which foraging is low in both clear and highly turbid conditions due to foraging-related risk and visual constraints, respectively. Consequently, the positive trait-mediated indirect effect (TMIE) of the top predator on the basal resource is predicted to peak at low turbidity and decline thereafter until it reaches an asymptote of zero at intermediate turbidity levels (when foraging equals that which is predicted when the top predator is absent). We used field observations and a laboratory experiment to test our model predictions. In support, we found humped-shaped relationships between planktivory and turbidity for several zooplanktivorous fishes from diverse freshwater ecosystems with predation risk. Further, our experiment demonstrated that predation risk reduced zooplanktivory by yellow perch (Perca flavescens) at a low turbidity, but had no effect on consumption at

  11. Effect of enzymatic mash treatment and storage on phenolic composition, antioxidant activity, and turbidity of cloudy apple juice.

    PubMed

    Oszmiański, Jan; Wojdylo, Aneta; Kolniak, Joanna

    2009-08-12

    The effects of different commercial enzymatic mash treatments on yield, turbidity, color, and polyphenolic and sediment of procyanidins content of cloudy apple juice were studied. Addition of pectolytic enzymes to mash treatment had positive effect on the production of cloud apple juices by improving polyphenolic contents, especially procyanidins and juice yields (68.3% in control samples to 77% after Pectinex Yield Mash). As summary of the effect of enzymatic mash treatment, polyphenol contents in cloudy apple juices significantly increased after Pectinex Yield Mash, Pectinex Smash XXL, and Pectinex XXL maceration were applied but no effect was observed after Pectinex Ultra-SPL I Panzym XXL use, compared to the control samples. The content of polymeric procyanidins represented 50-70% of total polyphenols, but in the present study, polymeric procyanidins were significantly lower in juices than in fruits and also affected by enzymatic treatment (Pectinex AFP L-4 and Panzym Yield Mash) compared to the control samples. The enzymatic treatment decreased procyanidin content in most sediment with the exception of Pectinex Smash XXL and Pectinex AFP L-4. Generally in samples that were treated by pectinase, radical scavenging activity of cloudy apple juices was increased compared to the untreated reference samples. The highest radical scavenging activity was associated with Pectinex Yield Mash, Pectinex Smash XXL, and Pectinex XXL enzyme and the lowest activity with Pectinex Ultra SP-L and Pectinex APFL-4. However, in the case of enzymatic mash treatment cloudy apple juices showed instability of turbidity and low viscosity. These results must be ascribed to the much higher hydrolysis of pectin by enzymatic preparation which is responsible for viscosity. During 6 months of storage at 4 degrees C small changes in analyzed parameters of apple juices were observed.

  12. Time-gated backscattered ballistic light imaging of objects in turbid water

    NASA Astrophysics Data System (ADS)

    Zevallos L., Manuel E.; Gayen, S. K.; Alrubaiee, M.; Alfano, R. R.

    2005-01-01

    Time-gated optical imaging of objects in turbid water was carried out in a backscattering geometry using light pulses of different pulse widths and a time-gated detection scheme with variable gate widths. Experimental results demonstrate that ultrashort pulsed illumination with ultrashort gated detection significantly improve image contrast as compared to any other combinations. These results are important for imaging objects embedded in turbid media, such as cloud, fog, smoke, murky water, and biological tissues for military, civilian, and medical applications.

  13. Historical Land-Use Influences the Long-Term Stream Turbidity Response to a Wildfire

    NASA Astrophysics Data System (ADS)

    Harrison, Evan T.; Dyer, Fiona; Wright, Daniel W.; Levings, Chris

    2014-02-01

    Wildfires commonly result in an increase in stream turbidity. However, the influence of pre-fire land-use practices on post-fire stream turbidity is not well understood. The Lower Cotter Catchment (LCC) in south-eastern Australia is part of the main water supply catchment for Canberra with land in the catchment historically managed for a mix of conservation (native eucalypt forest) and pine ( Pinus radiata) plantation. In January 2003, wildfires burned almost all of the native and pine forests in the LCC. A study was established in 2005 to determine stream post-fire turbidity recovery within the native and pine forest areas of the catchment. Turbidity data loggers were deployed in two creeks within burned native forest and burned pine forest areas to determine turbidity response to fire in these areas. As a part of the study, we also determined changes in bare soil in the native and pine forest areas since the fire. The results suggest that the time, it takes turbidity levels to decrease following wildfire, is dependent upon the preceding land-use. In the LCC, turbidity levels decreased more rapidly in areas previously with native vegetation compared to areas which were previously used for pine forestry. This is likely because of a higher percentage of bare soil areas for a longer period of time in the ex-pine forest estate and instream stores of fine sediment from catchment erosion during post-fire storm events. The results of our study show that the previous land-use may exert considerable control over on-going turbidity levels following a wildfire.

  14. Satellite assessment of hurricane-induced ocean turbidity for the southern U.S. coastline

    USGS Publications Warehouse

    Waters, K.; Brock, J.; Subramaniam, A.; Stumpf, R.P.; Armstrong, E.

    1997-01-01

    Advanced very high resolution radiometer images before and after three hurricanes were processed to estimate the reflectance difference between visible and near-infrared bands. The reflectance difference provides a measure of the turbidity in the water column. The images were compared to examine the influence of hurricanes on coastal waters Hurricanes were found to increase turbidity in a large area, with the greatest impact to the right side of the hurricane track. ??2005 Copyright SPIE - The International Society for Optical Engineering.

  15. Frequency domain photothermoacoustic signal amplitude dependence on the optical properties of water: turbid polyvinyl chloride-plastisol system.

    PubMed

    Spirou, Gloria M; Mandelis, Andreas; Vitkin, I Alex; Whelan, William M

    2008-05-10

    Photoacoustic (more precisely, photothermoacoustic) signals generated by the absorption of photons can be related to the incident laser fluence rate. The dependence of frequency domain photoacoustic (FD-PA) signals on the optical absorption coefficient (micro(a)) and the effective attenuation coefficient (micro(eff)) of a turbid medium [polyvinyl chloride-plastisol (PVCP)] with tissuelike optical properties was measured, and empirical relationships between these optical properties and the photoacoustic (PA) signal amplitude and the laser fluence rate were derived for the water (PVCP system with and without optical scatterers). The measured relationships between these sample optical properties and the PA signal amplitude were found to be linear, consistent with FD-PA theory: micro(a)=a(A/Phi)-b and micro(eff)=c(A/Phi)+d, where Phi is the laser fluence, A is the FD-PA amplitude, and a, ...,d are empirical coefficients determined from the experiment using linear frequency-swept modulation and a lock-in heterodyne detection technique. This quantitative technique can easily be used to measure the optical properties of general turbid media using FD-PAs.

  16. Progress in theoretical, experimental, and computational investigations in turbid tissue phantoms and human teeth using laser infrared photothermal radiometry

    NASA Astrophysics Data System (ADS)

    Mandelis, Andreas

    2002-03-01

    This paper reviews and describes the state-of-the-art in the development of frequency-domain infrared photothermal radiometry (FD-PTR) for biomedical and dental applications. The emphasis is placed on the measurement of the optical and thermal properties of tissue-like materials using FD-PTR. A rigorous three-dimensional thermal-wave formulation with three-dimensional diffuse and coherent photon-density-wave sources is presented, and is applied to data from model tissue phantoms and dental enamel samples. The combined theoretical, experimental and computational methodology shows good promise with regard to its analytical ability to measure optical properties of turbid media uniquely, as compared to PPTR, which exhibits uniqueness problems. From data sets obtained with calibrated test phantoms, the reduced optical scattering and absorption coefficients were found to be within 20% and 10%, respectively, from the independently derived values using Mie scattering theory and spectrophotometric measurements. Furthermore, the state-of-the-art and recent developments in applications of laser infrared FD-PTR to dental caries research is described, with examples and histological studies from carious dental tissue. The correlation of PTR signals with modulated dental luminescence is discussed as a very promising potential quantitative methodology for the clinical diagnosis of sub-surface incipient dental caries. The application of the turbid-medium thermal-wave model to the measurement of the optical absorption and scattering coefficients of enamel is also presented.

  17. Emplacement of massive turbidites linked to extinction of turbulence in turbidity currents

    NASA Astrophysics Data System (ADS)

    Cantero, Mariano I.; Cantelli, Alessandro; Pirmez, Carlos; Balachandar, S.; Mohrig, David; Hickson, Thomas A.; Yeh, Tzu-Hao; Naruse, Hajime; Parker, Gary

    2012-01-01

    Submarine turbidity currents are controlled by gravity acting on suspended sediments that pull water downslope along with them. In addition to suspended sediments, turbidity currents also transport sediments at the base of the flow, which causes the reorganization of basal sediments prior to the settling of suspended grains. However, as turbidity currents reach areas with minimal slope, they cross a fall-velocity threshold beyond which the suspended sediments begin to stratify the flow. This process extinguishes the turbulence near the bed. Here we use direct numerical simulation of turbidity currents to show that this extinction of turbulence eliminates the ability of the flow to re-entrain sediment and rework the sediment at the base of the flow. Our simulations indicate that deposits from flows without basal reworking should lack internal structures such as laminations. Under appropriate conditions, then, sustained delivery of fine sediments will therefore result in the emplacement of massive turbidites. We suggest that this mechanism can explain field observations of massive deposits that were emplaced gradually by dilute but powerful turbidity currents. We also conclude that turbulence in submarine turbidity currents is more fragile than river systems, and more sensitive to damping by the stratification of suspended sediment in the flow.

  18. Diurnal variability in turbidity and coral fluorescence on a fringing reef flat: Southern Molokai, Hawaii

    USGS Publications Warehouse

    Piniak, G.A.; Storlazzi, C.D.

    2008-01-01

    Terrigenous sediment in the nearshore environment can pose both acute and chronic stresses to coral reefs. The reef flat off southern Molokai, Hawaii, typically experiences daily turbidity events, in which trade winds and tides combine to resuspend terrigenous sediment and transport it alongshore. These chronic turbidity events could play a role in restricting coral distribution on the reef flat by reducing the light available for photosynthesis. This study describes the effects of these turbidity events on the Hawaiian reef coral Montipora capitata using in situ diurnal measurements of turbidity, light levels, and chlorophyll fluorescence yield via pulse-amplitude-modulated (PAM) fluorometry. Average surface irradiance was similar in the morning and the afternoon, while increased afternoon turbidity resulted in lower subsurface irradiance, higher fluorescence yield (??F/Fm???), and lower relative electron transport rates (rETR). Model calculations based on observed light extinction coeffecients suggest that in the absence of turbidity events, afternoon subsurface irradiances would be 1.43 times higher than observed, resulting in rETR for M. capitata that are 1.40 times higher.

  19. Swept Away by a Turbidity Current in Mendocino Submarine Canyon, California

    NASA Astrophysics Data System (ADS)

    Sumner, E.; Paull, C. K.

    2015-12-01

    Direct observations of turbidity currents in the ocean are rare, yet essential for validating and developing conceptual models of these enigmatic flows. We present a novel set of observations and measurements collected by a remotely operated vehicle entrained within a turbidity current in Mendocino Canyon, California. The flow had a two layer structure with a thin (0.5 to 30 m), relatively dense (<0.04 vol %) and fast (up to ~1.7 m/s) wedge-shaped lower layer overlain by a thicker (up to 89m) more dilute and slower current. The fast moving lower layer lagged the slow moving, dilute flow front by 14 min, which we infer resulted from the interaction of two initial pulses. The two layers were strongly coupled, and the sharp interface between the layers was characterized by a wave-like instability. This is the first field-scale data from a turbidity current to show (i) the complex dynamics of the head of a turbidity current and (ii) the presence of multiple layers within the same event. This data set provides a new perspective on the character of turbidity currents in the ocean. The data pose challenges not simply for understanding the dynamics of turbidity currents but also for how we interpret existing data based on cable breaks and how we might measure similar flows in the future.

  20. Turbidity currents and turbidites: towards quantitative interpretation and prediction of process and product.

    NASA Astrophysics Data System (ADS)

    Eggenhuisen, J. T.; Cartigny, M.; de Leeuw, J.; Pohl, F.

    2015-12-01

    Many decades of studies of deposits and seascapes formed by turbidity currents have established a robust observational framework that demonstrates that depositional and morphological patterns are repeated through time and space. The process-modeling community has similarly made progress in the understanding of the distribution of suspended sediment, velocity, and turbulence in turbidity currents, together shaping the "flow structure". Thus, now is the time to integrate, and investigate in more detail how the process of sediment erosion, transport, and deposition by turbidity currents is related to observed systematics in the physical products preserved in the geological record. Here we review recent breakthroughs in theoretical understanding of turbulent suspended sediment transport capacity. These breakthroughs allow us to understand the coupling between the flow field of turbidity currents, the kinematics of which have long been established, and the carrying capacity of sediment. This leads to robust first order estimators of the velocity and suspended sediment distribution within turbidity currents. These estimators can be applied straightforwardly to investigate natural systems. Two types of examples are explored: application to modern seafloor systems results in sediment budget estimations of natural turbidity current channels and canyons. Application to ancient turbidite deposits in the rock record displays how the present state of understanding can be used for quantitative process inversion from the product. This should ultimately lead to predictive capabilities of rock-body characteristics in the subsurface.

  1. Time reversal optical tomography locates fluorescent targets in a turbid medium

    NASA Astrophysics Data System (ADS)

    Wu, Binlin; Cai, W.; Gayen, S. K.

    2013-03-01

    A fluorescence optical tomography approach that extends time reversal optical tomography (TROT) to locate fluorescent targets embedded in a turbid medium is introduced. It uses a multi-source illumination and multi-detector signal acquisition scheme, along with TR matrix formalism, and multiple signal classification (MUSIC) to construct pseudo-image of the targets. The samples consisted of a single or two small tubes filled with water solution of Indocyanine Green (ICG) dye as targets embedded in a 250 mm × 250 mm × 60 mm rectangular cell filled with Intralipid-20% suspension as the scattering medium. The ICG concentration was 1μM, and the Intralipid-20% concentration was adjusted to provide ~ 1-mm transport length for both excitation wavelength of 790 nm and fluorescence wavelength around 825 nm. The data matrix was constructed using the diffusely transmitted fluorescence signals for all scan positions, and the TR matrix was constructed by multiplying data matrix with its transpose. A pseudo spectrum was calculated using the signal subspace of the TR matrix. Tomographic images were generated using the pseudo spectrum. The peaks in the pseudo images provided locations of the target(s) with sub-millimeter accuracy. Concurrent transmission TROT measurements corroborated fluorescence-TROT findings. The results demonstrate that TROT is a fast approach that can be used to obtain accurate three-dimensional position information of fluorescence targets embedded deep inside a highly scattering medium, such as, a contrast-enhanced tumor in a human breast.

  2. Variability in turbidity current frequency within a central Portuguese margin canyon

    NASA Astrophysics Data System (ADS)

    Allin, Joshua R.; Talling, Peter J.; Hunt, James E.; Clare, Michael E.; Pope, Ed

    2015-04-01

    Submarine canyons constitute one of the most important pathways for sediment transport into ocean basins. For this reason, understanding canyon architecture and sedimentary processes has significance for oil and gas reservoir characterisation, carbon budgets and geohazard assessment. Canyon sedimentation in the form of turbidity-currents is known to operate on a variety of scales and result from a number of different processes, including landslides, river-derived hyperpycnal flows and tidal or storm resuspension. Despite the expanding knowledge of turbidity current triggers, the spatial variability in turbidity current frequency within most canyon systems is not well defined. Here, new chronologies from cores in the lower reaches of Nazaré Canyon illustrate changes in turbidity current frequency and their relationship to sea level. These flows were relatively frequent during the last glacial maximum and the last deglaciation, with an average recurrence interval of ~70 years. Mid to early Holocene slowdown in activity (avg. recurrence of 1625 years) appears to occur later than other systems along the Iberian margin. Cores from the Iberian Abyssal Plain also provide the first recurrence interval estimates for large run-out turbidity currents from the central Portuguese margin. These large turbidity currents have an average recurrence interval of 2750 years, broadly comparable to modern turbidity flow events in the lower Nazaré Canyon. This indicates that Nazaré Canyon acted as a depocentre, capturing large volumes of sediment during glacial periods prior to large scale canyon flushing events. However, this sediment capture has largely been restricted to the middle and upper canyon since stabilisation of Holocene sea level. Recurrence intervals suggest that large turbidity flows which flush the canyon operate on a timescale independent of the sea level forcing evident in the lower canyon. While instability-triggered landsliding and tidal/storm resuspension are

  3. Relations Between Environmental and Water-Quality Variables and Escherichia coli in the Cuyahoga River With Emphasis on Turbidity as a Predictor of Recreational Water Quality, Cuyahoga Valley National Park, Ohio, 2008

    USGS Publications Warehouse

    Brady, Amie M.G.; Plona, Meg B.

    2009-01-01

    During the recreational season of 2008 (May through August), a regression model relating turbidity to concentrations of Escherichia coli (E. coli) was used to predict recreational water quality in the Cuyahoga River at the historical community of Jaite, within the present city of Brecksville, Ohio, a site centrally located within Cuyahoga Valley National Park. Samples were collected three days per week at Jaite and at three other sites on the river. Concentrations of E. coli were determined and compared to environmental and water-quality measures and to concentrations predicted with a regression model. Linear relations between E. coli concentrations and turbidity, gage height, and rainfall were statistically significant for Jaite. Relations between E. coli concentrations and turbidity were statistically significant for the three additional sites, and relations between E. coli concentrations and gage height were significant at the two sites where gage-height data were available. The turbidity model correctly predicted concentrations of E. coli above or below Ohio's single-sample standard for primary-contact recreation for 77 percent of samples collected at Jaite.

  4. Changes of turbidity during the phenol oxidation by photo-Fenton treatment.

    PubMed

    Villota, Natalia; Camarero, Luis M; Lomas, Jose M; Perez, Jonatan

    2014-11-01

    Turbidity presented by phenol solutions oxidized with Fenton reagent shows the tendency of a first order intermediate kinetics. Thus, turbidity can be considered a representative parameter of the presence of intermediate oxidation species, which are generated along the decomposition of toxic and reluctant contaminants, such as phenol. Moreover, that parameter presents a linear dependence with the catalyst dosage, but is also determined by the initial contaminant load. When analyzing the oxidation mechanism of phenol, it is found that the maximum turbidity occurs when the treatment is carried out at oxidant to phenol molar ratios R = 4.0. These oxidation conditions correspond to the presence of a reaction mixture mainly composed of dihydroxylated rings, precursors of the muconic acid formation. The oxidation via "para" comprises the formation reactions of charge transfer complexes (quinhydrone), between the para-dihydroxylated intermediates (hydroquinone) and the para-substituted quinones (p-benzoquinone), which are quite unstable and reactive species, quickly decomposed into hydroxyhydroquinones. Working with oxidant ratios up to R = 6.0, the maximum observed value of turbidity in the oxidized solutions is kept almost constant. It is found that, in these conditions, the pyrogallol formation is maximal, what is generated through the degradation of ortho-species (catechol and ortho-benzoquinone) and meta-substituted (resorcinol). Operating with ratios over R = 6.0, these intermediates are decomposed into biodegradable acids, generating lower turbidity in the solution. Then, the residual turbidity is a function of the molar ratio of the ferrous ions vs. moles of oxidant utilized in the essays, that lets to estimate the stoichiometric dosage of catalyst as 20 mg/L at pH = 3.0, whereas operating in stoichiometric conditions, R = 14.0, the residual turbidity of water results almost null.

  5. Multiple Scattering Effects on Pulse Propagation in Optically Turbid Media.

    NASA Astrophysics Data System (ADS)

    Joelson, Bradley David

    The effects of multiple scattering in a optically turbid media is examined for an impulse solution to the radiative transfer equation for a variety of geometries and phase functions. In regions where the complexities of the phase function proved too cumbersome for analytic methods Monte Carlo techniques were developed to describe the entire scalar radiance distribution. The determination of a general spread function is strongly dependent on geometry and particular regions where limits can be placed on the variables of the problem. Hence, the general spread function is first simplified by considering optical regions which reduce the complexity of the variable dependence. First, in the small-angle limit we calculate some contracted spread functions along with their moments and then use Monte Carlo techniques to establish the limitations imposed by the small-angle approximation in planar geometry. The point spread function (PSF) for a spherical geometry is calculated for the full angular spread in the forward direction of ocean waters using Monte Carlo methods in the optically thin and moderate depths and analytic methods in the diffusion domain. The angular dependence of the PSF for various ocean waters is examined for a range of optical parameters. The analytic method used in the diffusion calculation is justified by examining the angular dependence of the radiance of a impulse solution in a planar geometry for a prolongated Henyey-Greenstein phase function of asymmetry factor approximately equal to that of the ocean phase functions. The Legendre moments of the radiance are examined in order to examine the viability of the diffusion approximation which assumes a linearly anisotropic angular distribution for the radiance. A realistic lidar calculation is performed for a variety of ocean waters to determine the effects of multiple scattering on the determination of the speed of sound by using the range gated frequency spectrum of the lidar signal. It is shown that the

  6. Guidelines and Procedures for Computing Time-Series Suspended-Sediment Concentrations and Loads from In-Stream Turbidity-Sensor and Streamflow Data

    USGS Publications Warehouse

    Rasmussen, Patrick P.; Gray, John R.; Glysson, G. Douglas; Ziegler, Andrew C.

    2009-01-01

    In-stream continuous turbidity and streamflow data, calibrated with measured suspended-sediment concentration data, can be used to compute a time series of suspended-sediment concentration and load at a stream site. Development of a simple linear (ordinary least squares) regression model for computing suspended-sediment concentrations from instantaneous turbidity data is the first step in the computation process. If the model standard percentage error (MSPE) of the simple linear regression model meets a minimum criterion, this model should be used to compute a time series of suspended-sediment concentrations. Otherwise, a multiple linear regression model using paired instantaneous turbidity and streamflow data is developed and compared to the simple regression model. If the inclusion of the streamflow variable proves to be statistically significant and the uncertainty associated with the multiple regression model results in an improvement over that for the simple linear model, the turbidity-streamflow multiple linear regression model should be used to compute a suspended-sediment concentration time series. The computed concentration time series is subsequently used with its paired streamflow time series to compute suspended-sediment loads by standard U.S. Geological Survey techniques. Once an acceptable regression model is developed, it can be used to compute suspended-sediment concentration beyond the period of record used in model development with proper ongoing collection and analysis of calibration samples. Regression models to compute suspended-sediment concentrations are generally site specific and should never be considered static, but they represent a set period in a continually dynamic system in which additional data will help verify any change in sediment load, type, and source.

  7. Extraction of natural coagulant from peanut seeds for treatment of turbid water

    NASA Astrophysics Data System (ADS)

    Birima, A. H.; Hammad, H. A.; Desa, M. N. M.; Muda, Z. C.

    2013-06-01

    This study investigates the potential of peanut seeds as an environmental friendly and natural coagulant for the treatment of high turbid water. The peanut seeds have been used after oil extraction; and the active coagulation component was extracted by distilled water and salt solution of different salt concentrations. The salts used were NaCl, KNO3, KCl, NH4Cl and NaNO3. Synthetic water with 200 NTU turbidity was used. Peanut extracted with NaCl (PC-NaCl) could effectively remove 92% of the 200 NTU turbidity using only 20 mg/l, while peanut seeds extracted with distilled water (PC-DW) could remove only 31.5% of the same turbidity with the same dosage. The coagulant dosage did not affected by the concentration of the salt solution, however, residual turbidity decreased with increasing the concentration of the salt; and the relationship was found to be a second order polynomial curve with R2 of 0.9312. The other salts tested were also found to be good solvents to extract the active coagulation component with no much difference from NaCl solution in terms of efficiency.

  8. A new approach using coagulation rate constant for evaluation of turbidity removal

    NASA Astrophysics Data System (ADS)

    Al-Sameraiy, Mukheled

    2015-09-01

    Coagulation-flocculation-sedimentation processes for treating three levels of bentonite synthetic turbid water using date seeds (DS) and alum (A) coagulants were investigated in the previous research work. In the current research, the same experimental results were used to adopt a new approach on a basis of using coagulation rate constant as an investigating parameter to identify optimum doses of these coagulants. Moreover, the performance of these coagulants to meet (WHO) turbidity standard was assessed by introducing a new evaluating criterion in terms of critical coagulation rate constant (kc). Coagulation rate constants (k2) were mathematically calculated in second order form of coagulation process for each coagulant. The maximum (k2) values corresponded to doses, which were obviously to be considered as optimum doses. The proposed criterion to assess the performance of coagulation process of these coagulants was based on the mathematical representation of (WHO) turbidity guidelines in second order form of coagulation process stated that (k2) for each coagulant should be ≥ (kc) for each level of synthetic turbid water. For all tested turbid water, DS coagulant could not satisfy it. While, A coagulant could satisfy it. The results obtained in the present research are exactly in agreement with the previous published results in terms of finding optimum doses for each coagulant and assessing their performances. On the whole, it is recommended considering coagulation rate constant to be a new approach as an indicator for investigating optimum doses and critical coagulation rate constant to be a new evaluating criterion to assess coagulants' performance.

  9. Turbidity and chlorine demand reduction using alum and moringa flocculation before household chlorination in developing countries.

    PubMed

    Preston, Kelsey; Lantagne, Daniele; Kotlarz, Nadine; Jellison, Kristen

    2010-03-01

    Over 1.1 billion people in the world lack access to improved drinking water. Diarrhoeal and other waterborne diseases cause an estimated 1.87 million deaths per year. The Safe Water System (SWS) is a household water treatment intervention that reduces diarrhoeal disease incidence among users in developing countries. Turbid waters pose a particular challenge to implementation of SWS programmes; although research shows that a 3.75 mg l(-1) sodium hypochlorite dose effectively treats turbid waters, users sometimes object to the strong chlorine taste and prefer to drink water that is more aesthetically pleasing. This study investigated the efficacy of two locally available chemical water treatments-alum and Moringa oleifera flocculation-to reduce turbidity and chlorine demand at turbidities of 10, 30, 70, 100 and 300 NTU. Both treatments effectively reduced turbidity (alum flocculation 23.0-91.4%; moringa flocculation 14.2-96.2%). Alum flocculation effectively reduced chlorine demand compared with controls at 30, 70, 100 and 300 NTU (p=0.01-0.06). Moringa flocculation increased chlorine demand to the point where adequate free chlorine residual was not maintained for 24 hours after treatment. Alum pretreatment is recommended in waters>or=30 NTU for optimum water disinfection. Moringa flocculation is not recommended before chlorination.

  10. Characteristics of turbulent kinetic energy dissipation rate and turbidity near the coast of East China Sea

    NASA Astrophysics Data System (ADS)

    Zhang, Yanwei; Xu, Huiping; Qin, Rufu; Xu, Changwei; Fan, Daidu

    2016-09-01

    The East China Sea (ECS) has a high suspended-sediment concentration because of the influence of the Changjiang River, indicated by high turbidity in the water. Considering the islands offthe coast and the complex topography, and the strong influence of tides and wind, the coast offthe ECS is a typical region with strong oceanic mixing processes. The changes in the dynamic processes near the bottom play an important role in the control of water turbidity. The turbulent kinetic energy dissipation rate ( ɛ ) is a parameter that shows the strength of ocean mixing. This is estimated based on a structure method using current velocity that is measured by a high-frequency Acoustic Doppler Current Profiler (ADCP) from a seafloor observatory in the ECS. The results indicate strong ocean mixing processes with a mean ɛ value of 5.7×10-5 W/kg and distinct tidal variations in the dissipation rate. Conversely, the variation of the water turbidity leads to changes in the water dynamical structure near the bottom. Comparing the dissipation rate with the turbidity near the bottom boundary layer, we find that the high turbidity mimics strong ocean mixing.

  11. Extraction of anisotropic parameters of turbid media using hybrid model comprising differential- and decomposition-based Mueller matrices.

    PubMed

    Liao, Chia-Chi; Lo, Yu-Lung

    2013-07-15

    A hybrid model comprising the differential Mueller matrix formalism and the Mueller matrix decomposition method is proposed for extracting the linear birefringence (LB), linear dichroism (LD), circular birefringence (CB), circular dichroism (CD), and depolarization properties (Dep) of turbid optical samples. In contrast to the differential-based Mueller matrix method, the proposed hybrid model provides full-range measurements of all the anisotropic properties of the optical sample. Furthermore, compared to the decomposition-based Mueller matrix method, the proposed model is insensitive to the multiplication order of the constituent basis matrices. The validity of the proposed method is confirmed by extracting the anisotropic properties of a compound chitosan-glucose-microsphere sample with LB/CB/Dep properties and two ferrofluidic samples with CB/CD/Dep and LB/LD/Dep properties, respectively. It is shown that the proposed hybrid model not only yields full-range measurements of all the anisotropic parameters, but is also more accurate and more stable than the decomposition method. Moreover, compared to the decomposition method, the proposed model more accurately reflects the dependency of the phase retardation angle and linear dichroism angle on the direction of the external magnetic field for ferrofluidic samples. Overall, the results presented in this study confirm that the proposed model has significant potential for extracting the optical parameters of real-world samples characterized by either single or multiple anisotropic properties.

  12. Turbidity as a method of preparing sperm dilutions in the echinoid sperm/egg bioassay

    SciTech Connect

    Hall, T.J.; Haley, R.K.; Battan, K.J. )

    1993-11-01

    The use of turbidimeter for preparing sperm dilutions used in the echinoid sperm/egg bioassay was evaluated. Regression analyses of the relationship between sperm density and turbidity for the sea urchins Strongylocentrotus purpuratus and Strongylocentrotus droebachiensis and the sand dollar Dendraster excentricus indicated that although there were slope differences for each species, each coefficient of determination was highly significant. For Dendraster excentricus, triplicate hemacytometer counts over a range of turbidities as well as repeated preparations of a single sperm turbidity indicated similar variability for each. The use of the turbidimeter has time-saving advantages over conventional hemacytometer methods without sacrificing precision. Sperm dilutions can be prepared rapidly, minimizing seawater sperm preactivation before test initiation, and may therefore contribute to increased test precision.

  13. Optical imaging through turbid media with a degenerate four-wave mixing correlation time gate

    DOEpatents

    Sappey, Andrew D.

    1998-04-14

    Optical imaging through turbid media is demonstrated using a degenerate four-wave mixing correlation time gate. An apparatus and method for detecting ballistic and/or snake light while rejecting unwanted diffusive light for imaging structures within highly scattering media are described. Degenerate four-wave mixing (DFWM) of a doubled YAG laser in rhodamine 590 is used to provide an ultrafast correlation time gate to discriminate against light that has undergone multiple scattering and therefore has lost memory of the structures within the scattering medium. Images have been obtained of a test cross-hair pattern through highly turbid suspensions of whole milk in water that are opaque to the naked eye, which demonstrates the utility of DFWM for imaging through turbid media. Use of DFWM as an ultrafast time gate for the detection of ballistic and/or snake light in optical mammography is discussed.

  14. Negative consequences of glacial turbidity for the survival of freshwater planktonic heterotrophic flagellates.

    PubMed

    Sommaruga, Ruben; Kandolf, Georg

    2014-02-17

    Heterotrophic (phagotrophic) flagellates are key components of planktonic food webs in freshwater and marine ecosystems because they are the main consumers of bacteria. Although they are ubiquitous in aquatic ecosystems, they were numerically undetectable in turbid glacier-fed lakes. Here we show that glacial particles had negative effects on the survival and growth of heterotrophic flagellates. The effect of glacial particles was concentration-dependent and was caused by their interference with bacterial uptake rather than by physical damage. These results are the first to reveal why establishment of heterotrophic flagellates populations is hindered in very turbid glacial lakes. Because glaciers are vanishing around the world, recently formed turbid meltwater lakes represent an excellent opportunity to understand the environmental conditions that probably shaped the establishment of lake communities at the end of the last glaciation.

  15. Swept away by a turbidity current in Mendocino submarine canyon, California

    NASA Astrophysics Data System (ADS)

    Sumner, E. J.; Paull, C. K.

    2014-11-01

    We present unique observations and measurements of a dilute turbidity current made with a remotely operated vehicle in 400 m water depth near the head of Mendocino Canyon, California. The flow had a two-layer structure with a thin (0.5 to 30 m), relatively dense (<0.04 vol %) and fast (up to ~1.7 m/s) wedge-shaped lower layer overlain by a thicker (up to 89 m) more dilute and slower current. The fast moving lower layer lagged the slow moving, dilute flow front by 14 min, which we infer resulted from the interaction of two initial pulses. The two layers were strongly coupled, and the sharp interface between the layers was characterized by a wave-like instability. This is the first field-scale data from a turbidity current to show (i) the complex dynamics of the head of a turbidity current and (ii) the presence of multiple layers within the same event.

  16. Coagulation of highly turbid suspensions using magnesium hydroxide: effects of slow mixing conditions.

    PubMed

    Ayoub, George M; BinAhmed, Sara W; Al-Hindi, Mahmoud; Azizi, Fouad

    2014-09-01

    Laboratory experiments were carried out to study the effects of slow mixing conditions on magnesium hydroxide floc size and strength and to determine the turbidity and total suspended solid (TSS) removal efficiencies during coagulation of highly turbid suspensions. A highly turbid kaolin clay suspension (1,213 ± 36 nephelometric turbidity units (NTU)) was alkalized to pH 10.5 using a 5 M NaOH solution; liquid bittern (LB) equivalent to 536 mg/L of Mg(2+) was added as a coagulant, and the suspension was then subjected to previously optimized fast mixing conditions of 100 rpm and 60 s. Slow mixing speed (20, 30, 40, and 50 rpm) and time (10, 20, and 30 min) were then varied, while the temperature was maintained at 20.7 ± 1 °C. The standard practice for coagulation-flocculation jar test ASTM D2035-13 (2013) was followed in all experiments. Relative floc size was monitored using an optical measuring device, photometric dispersion analyzer (PDA 2000). Larger and more shear resistant flocs were obtained at 20 rpm for both 20- and 30-min slow mixing times; however, given the shorter duration for the former, the 20-min slow mixing time was considered to be more energy efficient. For slow mixing camp number (Gt) values in the range of 8,400-90,000, it was found that the mixing speed affected floc size and strength more than the time. Higher-turbidity removal efficiencies were achieved at 20 and 30 rpm, while TSS removal efficiency was higher for the 50-rpm slow mixing speed. Extended slow mixing time of 30 min yielded better turbidity and TSS removal efficiencies at the slower speeds.

  17. Factors contributing to hypoxia in a highly turbid, macrotidal estuary (the Gironde, France).

    PubMed

    Lanoux, Aurélie; Etcheber, Henri; Schmidt, Sabine; Sottolichio, Aldo; Chabaud, Gérard; Richard, Marion; Abril, Gwenaël

    2013-03-01

    Dissolved oxygen (DO) is a fundamental parameter of coastal water quality, as it is necessary to aquatic biota, and it provides an indication of organic matter decomposition in waters and their degree of eutrophication. We present here a 7 year time series of DO concentration and ancillary parameters (river discharge, water level, turbidity, temperature, and salinity) from the MAGEST high-frequency monitoring network, at four automated stations in the central and fluvial regions of the macrotidal Gironde Estuary, one of the largest European estuaries. The spatio-temporal variability of DO at different time scales was first related to the migration and position of the maximum turbidity zone in this extremely turbid estuary. Since 2005, the Gironde Estuary has recorded several borderline hypoxic situations (DO close to 2 mg L(-1)) and a 7 day-long hypoxic event (DO < 2 mg L(-1)) in July 2006. Summer hypoxia occurred exclusively in the fluvial, low salinity, and high turbidity sections of the estuary and was significantly more pronounced in front of the large urban area of Bordeaux (715 000 inhabitants). Detailed analysis of the data at the seasonal, neap-spring and semi-diurnal tidal time scales, reveals that hypoxia in this area occurred: (i) in the maximum turbidity zone; (ii) during the spring to neap tide transition; (iii) at highest water temperature; and (iv) at lowest river discharge; there was also evidence of an additional negative impact of sewage treatment plants of Bordeaux city. Enhancement of respiration by turbidity, temperature and inputs of domestic biodegradable organic matter and ammonia, versus renewal of waters and dispersion of reduced pollutants with the river discharge, appeared as the dominant antagonist processes that controlled the occurrence of summer hypoxia. In the context of long-term environmental changes (increase in temperature and population, decrease in summer river discharge), the occurrence of severe hypoxia could not be excluded

  18. Effects of turbidity on predation vulnerability of juvenile humpback chub to rainbow and brown trout

    USGS Publications Warehouse

    Ward, David L.; Morton-Starner, Rylan; Vaage, Benjamin M.

    2016-01-01

    Predation on juvenile native fish by introduced rainbow trout Oncorhynchus mykiss and brown trout Salmo trutta is considered a significant threat to the persistence of endangered humpback chub Gila cypha in the Colorado River in Grand Canyon. Diet studies of rainbow and brown trout in Glen and Grand canyons indicate that these species eat native fish, but impacts are difficult to assess because predation vulnerability is highly variable depending on the physical conditions under which the predation interactions take place. We conducted laboratory experiments to evaluate how short-term predation vulnerability of juvenile humpback chub changes in response to changes in turbidity. In overnight laboratory trials, we exposed hatchery-reared juvenile humpback chub and bonytail Gila elegans (a surrogate for humpback chub) to adult rainbow and brown trout at turbidities ranging from 0 to 1,000 formazin nephlometric units. We found that turbidity as low as 25 formazin nephlometric units significantly reduced predation vulnerability of bonytail to rainbow trout and led to a 36% mean increase in survival (24–60%, 95% CI) compared to trials conducted in clear water. Predation vulnerability of bonytail to brown trout at 25 formazin nephlometric units also decreased with increasing turbidity and resulted in a 25% increase in survival on average (17–32%, 95% CI). Understanding the effects of predation by trout on endangered humpback chub is important when evaluating management options aimed at preservation of native fishes in Grand Canyon National Park. This research suggests that relatively small changes in turbidity may be sufficient to alter predation dynamics of trout on humpback chub in the mainstem Colorado River and that turbidity manipulation may warrant further investigation as a fisheries management tool.

  19. Feasibility of turbidity removal by high-gradient superconducting magnetic separation.

    PubMed

    Zeng, Hua; Li, Yiran; Xu, Fengyu; Jiang, Hao; Zhang, Weimin

    2015-01-01

    Several studies have focused on pollutant removal by magnetic seeding and high-gradient superconducting magnetic separation (HGSMS). However, few works reported the application of HGSMS for treating non-magnetic pollutants by an industrial large-scale system. The feasibility of turbidity removal by a 600 mm bore superconducting magnetic separation system was evaluated in this study. The processing parameters were evaluated by using a 102 mm bore superconducting magnetic separation system that was equipped with the same magnetic separation chamber that was used in the 600 mm bore system. The double-canister system was used to process water pollutants. Analytical grade magnetite was used as a magnetic seed and the turbidity of the simulated raw water was approximately 110 NTU, and the effects of polyaluminum chloride (PAC) and magnetic seeds on turbidity removal were evaluated. The use of more PAC and magnetic seeds had few advantages for the HGSMS at doses greater than 8 and 50 mg/l, respectively. A magnetic intensity of 5.0 T was beneficial for HGSMS, and increasing the flow rate through the steel wool matrix decreased the turbidity removal efficiency. In the breakthrough experiments, 90% of the turbidity was removed when 100 column volumes were not reached. The processing capacity of the 600 mm bore industry-scale superconducting magnetic separator for turbidity treatment was approximately 78.0 m(3)/h or 65.5 × 10(4) m(3)/a. The processing cost per ton of water for the 600 mm bore system was 0.1 $/t. Thus, the HGSMS separator could be used in the following special circumstances: (1) when adequate space is not available for traditional water treatment equipment, especially the sedimentation tank, and (2) when decentralized sewage treatment HGSMS systems are easier to transport and install.

  20. Hysteresis in suspended sediment to turbidity relations due to changing particle size distributions

    USGS Publications Warehouse

    Landers, Mark N.; Sturm, Terry W.

    2013-01-01

    Turbidity (T) is the most ubiquitous of surrogate technologies used to estimate suspended-sediment concentration (SSC). The effects of sediment size on turbidity are well documented; however, effects from changes in particle size distributions (PSD) are rarely evaluated. Hysteresis in relations of SSC-to-turbidity (SSC~T) for single stormflow events was observed and quantified for a data set of 195 concurrent measurements of SSC, turbidity, discharge, velocity, and volumetric PSD collected during five stormflows in 2009–2010 on Yellow River at Gees Mill Road in metropolitan Atlanta, Georgia. Regressions of SSC-normalized turbidity (T/SSC) on concurrently measured PSD percentiles show an inverse, exponential influence of particle size on turbidity that is not constant across the size range of the PSD. The majority of the influence of PSD on T/SSC is from particles of fine-silt and smaller sizes (finer than 16 microns). This study shows that small changes in the often assumed stability of the PSD are significant to SSC~T relations. Changes of only 5 microns in the fine silt and smaller size fractions of suspended sediment PSD can produce hysteresis in the SSC~T rating that can increase error and produce bias. Observed SSC~T hysteresis may be an indicator of changes in sediment properties during stormflows and of potential changes in sediment sources. Trends in the PSD time series indicate that sediment transport is capacity-limited for sand-sized sediment in the channel and supply-limited for fine silt and smaller sediment from the hillslope.

  1. Hysteresis in suspended sediment to turbidity relations due to changing particle size distributions

    NASA Astrophysics Data System (ADS)

    Landers, Mark N.; Sturm, Terry W.

    2013-09-01

    Turbidity (T) is the most ubiquitous of surrogate technologies used to estimate suspended-sediment concentration (SSC). The effects of sediment size on turbidity are well documented; however, effects from changes in particle size distributions (PSD) are rarely evaluated. Hysteresis in relations of SSC-to-turbidity (SSC˜T) for single stormflow events was observed and quantified for a dataset of 195 concurrent measurements of SSC, turbidity, discharge, velocity, and volumetric PSD collected during five stormflows in 2009-2010 on Yellow River at Gees Mill Road in metropolitan Atlanta, Georgia. Regressions of SSC-normalized turbidity (T/SSC) on concurrently measured PSD percentiles show an inverse, exponential influence of particle size on turbidity that is not constant across the size range of the PSD. The majority of the influence of PSD on T/SSC is from particles of fine silt and smaller sizes (finer than 16 µm). This study shows that small changes in the often assumed stability of the PSD are significant to SSC˜T relations. Changes of only 5 µm in the fine silt and smaller size fractions of suspended sediment PSD can produce hysteresis in the SSC˜T rating that can increase error and produce bias. Observed SSC˜T hysteresis may be an indicator of changes in sediment properties during stormflows and of potential changes in sediment sources. Trends in the PSD time series indicate that sediment transport is capacity limited for sand-sized sediment in the channel and supply limited for fine silt and smaller sediment from the hillslope.

  2. Prey detection by great cormorant (Phalacrocorax carbo sinensis) in clear and in turbid water.

    PubMed

    Strod, Tamir; Izhaki, Ido; Arad, Zeev; Katzir, Gadi

    2008-03-01

    The scattering and absorption of light by water molecules and by suspended and dissolved matter (turbidity) degrade image transmission and, thus, underwater perception. We tested the effects on visual detection of prey size and distance (affecting apparent prey size) and of low-level water turbidity in hand-reared great cormorants (Phalacrocorax carbo sinensis) diving for natural prey (fish) in a forced-choice situation. The cormorants' detection of underwater prey relied on vision. The minimal tested subtending visual angle of the prey at detection ranged between approximately 34.2' (prey size constant; distance varied) and 9.5' (distance constant; prey size varied). For all tested distances (0.8-3.1 m) the mean detection success was significantly higher than the chance level. The probability of a correct choice declined significantly with increased distance, with Detection success=-0.034D+1.021 (where D is distance, r(2)=0.5, N=70, P<0.001). The combined effect of turbidity and distance on the probability of detection success was significant, with both variables having a negative effect: Detection success=-0.286D-0.224Tu+1.691 (where Tu is turbidity, r(2)=0.68, N=144, P<0.001). At prey detection threshold, the relationship between distance and turbidity was: D=3.79e(-4.55Tu). It is concluded that (i) the subtending angle of natural prey at detection was lower than that of resolution of square-wave, high-contrast grating and (ii) turbidity, at levels significantly lower than commonly used in behavioural experiments, had a pronounced effect on visually mediated behaviour patterns.

  3. A label-free fiber-optic Turbidity Affinity Sensor (TAS) for continuous glucose monitoring.

    PubMed

    Dutt-Ballerstadt, Ralph; Evans, Colton; Pillai, Arun P; Gowda, Ashok

    2014-11-15

    In this paper, we describe the concept of a novel implantable fiber-optic Turbidity Affinity Sensor (TAS) and report on the findings of its in-vitro performance for continuous glucose monitoring. The sensing mechanism of the TAS is based on glucose-specific changes in light scattering (turbidity) of a hydrogel suspension consisting of small particles made of crosslinked dextran (Sephadex G100), and a glucose- and mannose-specific binding protein - Concanavalin A (ConA). The binding of ConA to Sephadex particles results in a significant turbidity increase that is much greater than the turbidity contribution by the individual components. The turbidity of the TAS was measured by determining the intensity of light passing through the suspension enclosed within a small semi-permeable hollow fiber (OD: 220 μm, membrane thickness: 20 μm, molecular weight cut-off: 10 kDa) using fiber optics. The intensity of measured light of the TAS was proportional to the glucose concentration over the concentration range from 50mg/dL to 400mg/dL in PBS and whole blood at 37°C (R>0.96). The response time was approximately 4 min. The stability of the glucose response of the TAS decreased only slightly (by 20%) over an 8-day study period at 37°C. In conclusion, this study demonstrated proof-of-concept of the TAS for interstitial glucose monitoring. Due to the large signal amplitude of the turbidity change, and the lack of need for wavelength-specific emission and excitation filters, a very small, robust and compact TAS device with an extremely short optical pathlength could be feasibly designed and implemented for in-vivo glucose monitoring in people with diabetes.

  4. Dihydropyridine type calcium channel blocker-induced turbid dialysate in patients undergoing peritoneal dialysis.

    PubMed

    Yoshimoto, K; Saima, S; Nakamura, Y; Nakayama, M; Kubo, H; Kawaguchi, Y; Nishitani, H; Nakamura, Y; Yasui, A; Yokoyama, K; Kuriyama, S; Shirai, D; Kugiyama, A; Hayano, K; Fukui, H; Horigome, I; Amagasaki, Y; Tsubakihara, Y; Kamekawa, T; Ando, R; Tomura, S; Okamoto, R; Miwa, S; Koyama, T; Echizen, H

    1998-08-01

    We previously reported that manidipine, a new dihydropyridine type calcium channel blocker, produced chylous peritoneal dialysate being visually indistinguishable from infective peritonitis in 5 patients undergoing continuous ambulatory peritoneal dialysis (CAPD) [Yoshimoto et al. 1993]. To study whether such an adverse drug reaction would also be elicited by other commonly prescribed calcium channel blockers in CAPD patients, we have conducted postal inquiry to 15 collaborating hospitals and an institutional survey in International Medical Center of Japan as to the possible occurrence of calcium channel blocker-associated non-infective, turbid peritoneal dialysate in CAPD patients. Our diagnostic criteria for drug-induced turbidity of dialysate as a) it developed within 48 h after the administration of a newly introduced calcium channel blocker to the therapeutic regimen, b) absence of clinical symptoms of peritoneal inflammation (i.e., pyrexia, abdominal pain, nausea or vomiting), c) the fluid containing normal leukocyte counts and being negative for bacterial and fungal culture of the fluid, and d) it disappeared shortly after the withdrawal of the assumed causative agent. Results showed that 19 out of 251 CAPD patients given one of the calcium channel blockers developed non-infective turbid peritoneal dialysis that fulfilled all the above criteria. Four calcium channel blockers were suspected to be associated with the events: benidipine [2 out of 2 (100%) patients given the drug], manidipine [15 out of 36 (42%) patients], nisoldipine [1 out of 11 (9%) patients] and nifedipine [1 out of 159 (0.6%)] in descending order of frequency. None of the patients who received nicardipine, nilvadipine, nitrendipine, barnidipine and diltiazem (25, 7, 2, 1 and 8 patients, respectively) exhibited turbid dialysate. In conclusion, we consider that certain dihydropyridine type calcium channel blockers would cause turbid peritoneal dialysate being similar to that observed in

  5. Effect of substituted hydroxyl groups in the changes of solution turbidity in the oxidation of aromatic contaminants.

    PubMed

    Villota, N; Jm, Lomas; Lm, Camarero

    2017-01-01

    This paper deals with the changes of turbidity that are generated in aqueous solutions of phenol when they are oxidized by using different Fenton technologies. Results revealed that if the Fenton reaction was promoted with UV light, the turbidity that was generated in the water doubled. Alternatively, the use of ultrasonic waves produced an increase in turbidity which initially proceeded slowly, reaching intensities eight times higher than in the conventional Fenton treatment. As well, the turbidity showed a high dependence on pH. It is therefore essential to control acidity throughout the reaction. The maximum turbidity was generated when operating at pH = 2.0, and it slowly decreased with increasing to a value of pH = 3.0, at which the turbidity was the lowest. This result was a consequence of the presence of ferric ions in solution. At pH values greater than 3.5, the turbidity increased almost linearly until at pH = 5.0 reached its maximum intensity. In this range, ferrous ions may generate an additional contribution of radicals that promote the degradation of the phenol species that produce turbidity. Turbidity was enhanced at ratios R = 4.0 mol H2O2/mol C6H6O. This value corresponds to the stoichiometric ratio that leads to the production of turbidity-precursor species. Therefore, muconic acid would be a species that generate high turbidity in solution according to its isomerism. Also, the results revealed that the turbidity is not a parameter to which species contribute additively since interactions may occur among species that would enhance their individual contributions to it. Analyzing the oxidation of phenol degradation intermediates, the results showed that meta-substituted compounds (resorcinol) generate high turbidity in the wastewater. The presence of polar molecules, such as muconic acid, would provide the structural features that are necessary for resorcinol to act as a clip between two carboxylic groups, thus establishing directional

  6. Influence of temperature and turbidity on water COD detection by UV absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Zhou, Kun-peng; Bi, Wei-hong; Zhang, Qi-hang; Fu, Xing-hu; Wu, Guo-qing

    2016-11-01

    Ultraviolet (UV) absorption spectroscopy is used to detect the concentration of water chemical oxygen demand (COD). The UV absorption spectra of COD solutions are analyzed qualitatively and quantitatively. The partial least square (PLS) algorithm is used to model COD solution and the modeling results are compared. The influence of environmental temperature and turbidity is analyzed. These results show that the influence of temperature on the predicted value can be ignored. However, the change of turbidity can affect the detection results of UV spectra, and the COD detection error can be effectively compensated by establishing the single-element regression model.

  7. Optical imaging through turbid media using a degenerate-four-wave mixing correlation time gate

    SciTech Connect

    Bigio, I.J.; Strauss, C.E.M.; Zerkle, D.K.

    1998-11-01

    This is the final report of a three-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The authors have demonstrated the use of a degenerate-four-wave-mixing time gate to allow imaging through turbid media, with potential application to tissue imaging. A near infrared (NIR), long-pulse Cr{sup +3}:Li{sub 2}SrAlF{sub 6} laser was used as the light source (during most the project) for imaging through clear and turbid media. Preliminary experiments were also carried out with a continuous diode laser.

  8. Backscattering target detection in a turbid medium by use of circularly and linearly polarized light.

    PubMed

    Kartazayeva, S A; Ni, Xiaohui; Alfano, R R

    2005-05-15

    The polarization properties of the backscattered light from a turbid medium containing large-diameter (10.143-microm) and small-diameter (0.202-microm) spherical polystyrene particles are studied. It is shown that the difference in the polarization properties of the emerging light that originates at the target and that is backscattered from the medium allows for improvement of image contrast by use of polarized light. Based on the images obtained by the CCD camera, the polarization memory effect with circularly polarized light is demonstrated to have an advantage over the linear polarization technique in imaging a highly reflective target inside a turbid medium containing large particles.

  9. Determination of scattering functions and their effects on remote sensing of turbidity in natural waters

    NASA Technical Reports Server (NTRS)

    Ghovanlou, A. H.; Gupta, J. N.; Henderson, R. G.

    1977-01-01

    The development of quantitative analytical procedures for relating scattered signals, measured by a remote sensor, was considered. The applications of a Monte Carlo simulation model for radiative transfer in turbid water are discussed. The model is designed to calculate the characteristics of the backscattered signal from an illuminated body of water as a function of the turbidity level, and the spectral properties of the suspended particulates. The optical properties of the environmental waters, necessary for model applications, were derived from available experimental data and/or calculated from Mie formalism. Results of applications of the model are presented.

  10. Focusing light into desired patterns through turbid media by feedback-based wavefront shaping

    NASA Astrophysics Data System (ADS)

    Wan, Lipeng; Chen, Ziyang; Huang, Huiling; Pu, Jixiong

    2016-07-01

    We demonstrate that the focusing of light into desired patterns through turbid media can be realized using feedback-based wavefront shaping. Three desired focused patterns—a triangle, a circle, and a rectangle—are used as examples to study this ability. During the process of modulating scattered light, the Pearson's correlation coefficient is introduced as a feedback signal. It is found that the speckle field formed by the turbid media gradually transforms into the desired pattern through a process of modulation of the input beam wave front. The proposed approach has potential applications in biomedical treatment and laser material processing.

  11. Monte Carlo algorithm for efficient simulation of time-resolved fluorescence in layered turbid media.

    PubMed

    Liebert, A; Wabnitz, H; Zołek, N; Macdonald, R

    2008-08-18

    We present an efficient Monte Carlo algorithm for simulation of time-resolved fluorescence in a layered turbid medium. It is based on the propagation of excitation and fluorescence photon bundles and the assumption of equal reduced scattering coefficients at the excitation and emission wavelengths. In addition to distributions of times of arrival of fluorescence photons at the detector, 3-D spatial generation probabilities were calculated. The algorithm was validated by comparison with the analytical solution of the diffusion equation for time-resolved fluorescence from a homogeneous semi-infinite turbid medium. It was applied to a two-layered model mimicking intra- and extracerebral compartments of the adult human head.

  12. Turbidity anomaly and probability of slope failure following the 2011 Great Tohoku Earthquake

    NASA Astrophysics Data System (ADS)

    Noguchi, T.; Tanikawa, W.; Hirose, T.; Lin, W.; Kawagucci, S.; Yoshida, Y.; Honda, M. C.; Takai, K.; Kitazato, H.; Okamura, K.

    2011-12-01

    Turbidity anomaly at seafloor is often observed immediately after earthquakes (Thunnell et al., 1999: Mikada et al., 2006). Such turbidity anomaly at deepsea is thought to be results of the seismically induced landslides at trench slopes. Turbidity distribution was observed using turbidity meter (Seapoint Sensors Inc.) at the mainshock area of the 2011 off the Pacific coast Tohoku earthquake (Mw 9.0) one month after the event. Turbidity anomalies, in which the turbidity increased with depth, were observed near the seafloor at all four sites. The thickness of the anomalous zones increased with water depth; the thickness at station B, the deepest measurement site, was about 1300 m above the seafloor and the average particle concentration which is equivalent to turbidity in the zone was 1.5 mg/L. We analyzed the mineral composition and grain size distribution of the suspended particle collected one month after the earthquake and shallow sediment core collected before the earthquake at the mainshock area. The grain size of the suspended particles was ranged from 1 to 300μm, and XRD analysis confirmed the presence of chlorite, illite, quartz, and albite in the particles. These characteristics are similar to the subsurface sediment material. Earlier studies (Prior, 1984) have introduced a mathematical model for analysis of submarine slope stability that include the effect of vertical and horizontal seismic accelerations caused by the earthquake. We analyzed slope instability on the basis of their model using the physical properties (density and shear strength) of the shallow sediment core materials and the acceleration of 2011 off the Pacific coast Tohoku earthquake. Our results show that a submarine landslide can be induced by a very large ground acceleration, as high as 3 m/s2, even if the sediment layer on the sliding surface is not very thick. We interpret the high turbidity observed one month after the Tohoku earthquake as the result of thin submarine landsliding

  13. Nitrification and its oxygen consumption along the turbid Changjiang River plume

    NASA Astrophysics Data System (ADS)

    Hsiao, S. S.-Y.; Hsu, T.-C.; Liu, J.-W.; Xie, X.; Zhang, Y.; Lin, J.; Wang, H.; Yang, J.-Y. T.; Hsu, S.-C.; Dai, M.; Kao, S.-J.

    2013-05-01

    Nitrification rates of bulk water (NRb) and particle free (NRpf, particle > 3 μm eliminated) were determined along the Changjiang River plume in August 2011 by nitrogen isotope tracer technique. Dissolved oxygen (DO), community respiration rate (CR), nutrients, dissolved organic nitrogen, total suspended matter (TSM), particulate organic carbon/nitrogen (POC/PON), acid-leachable iron and manganese on suspended particles and both archaeal and β-proteobacterial amoA abundance on size-fractioned particle (> 3 μm and 0.22-3 μm) were measured. The NRb ranged from undetectable up to 4.6 μmol L-1 d-1 peaking at salinity of ~ 29. NRb values were positively correlated with ammonia concentration suggesting the importance of substrate in nitrification. In river mouth and inner plume, NRb was much higher than NRpf indicating nitrifying bacteria is mainly particle-associated, which was supported by amoA gene abundance and regression analysis of TSM and NRb. The estimated oxygen demand of nitrification accounted for 0.4% to 317% of CR. The nitrification oxygen demand is much higher than Redfield model's estimation (23%) indicating that oxygen might not be the sole oxidant though DO was sufficient (> 58 μmol kg-1). The excess nitrification oxygen demand showed tendency to occur at lower DO samples accompanying with higher acid-leachable Fe/Mn, which implied reactive Fe3+/Mn4+ may play a role as oxidant in nitrification process. Stoichiometric calculation suggested reactive Fe on particles was even 10-fold the oxidant demand for complete ammonia oxidation along all areas of the plume. The involvement of reactive iron and manganese in nitrification process in oxygenated water further complicated the nitrogen cycling in turbid river plume.

  14. Evaluating turbidity and suspended-sediment concentration relations from the North Fork Toutle River basin near Mount St. Helens, Washington; annual, seasonal, event, and particle size variations - a preliminary analysis.

    USGS Publications Warehouse

    Uhrich, Mark A.; Spicer, Kurt R.; Mosbrucker, Adam; Christianson, Tami

    2015-01-01

    Regression of in-stream turbidity with concurrent sample-based suspended-sediment concentration (SSC) has become an accepted method for producing unit-value time series of inferred SSC (Rasmussen et al., 2009). Turbidity-SSC regression models are increasingly used to generate suspended-sediment records for Pacific Northwest rivers (e.g., Curran et al., 2014; Schenk and Bragg, 2014; Uhrich and Bragg, 2003). Recent work developing turbidity-SSC models for the North Fork Toutle River in Southwest Washington (Uhrich et al., 2014), as well as other studies (Landers and Sturm, 2013, Merten et al., 2014), suggests that models derived from annual or greater datasets may not adequately reflect shorter term changes in turbidity-SSC relations, warranting closer inspection of such relations. In-stream turbidity measurements and suspended-sediment samples have been collected from the North Fork Toutle River since 2010. The study site, U.S. Geological Survey (USGS) streamgage 14240525 near Kid Valley, Washington, is 13 river km downstream of the debris avalanche emplaced by the 1980 eruption of Mount St. Helens (Lipman and Mullineaux, 1981), and 2 river km downstream of the large sediment retention structure (SRS) built from 1987–1989 to mitigate the associated sediment hazard. The debris avalanche extends roughly 25 km down valley from the edifice of the volcano and is the primary source of suspended sediment moving past the streamgage (NF Toutle-SRS). Other significant sources are debris flow events and sand deposits upstream of the SRS, which are periodically remobilized and transported downstream. Also, finer material often is derived from the clay-rich original debris avalanche deposit, while coarser material can derive from areas such as fluvially reworked terraces.

  15. Virus-Bacterium Coupling Driven by both Turbidity and Hydrodynamics in an Amazonian Floodplain Lake ▿ † ‡

    PubMed Central

    Barros, Nathan; Farjalla, Vinicius F.; Soares, Maria C.; Melo, Rossana C. N.; Roland, Fábio

    2010-01-01

    The importance of viruses in aquatic ecosystem functioning has been widely described. However, few studies have examined tropical aquatic ecosystems. Here, we evaluated for the first time viruses and their relationship with other planktonic communities in an Amazonian freshwater ecosystem. Coupling between viruses and bacteria was studied, focusing both on hydrologic dynamics and anthropogenic forced turbidity in the system (Lake Batata). Samples were taken during four hydrologic seasons at both natural and impacted sites to count virus-like particles (VLP) and bacteria. In parallel, virus-infected bacteria were identified and quantified by transmission electron microscopy (TEM). Viral abundance ranged from 0.5 × 107 ± 0.2 × 107 VLP ml−1 (high-water season, impacted site) to 1.7 × 107 ± 0.4 × 107 VLP ml−1 (low-water season, natural site). These data were strongly correlated with the bacterial abundance (r2 = 0.84; P < 0.05), which ranged from 1.0 × 106 ± 0.5 × 106 cells ml−1 (high water, impacted site) to 3.4 × 106 ± 0.7 × 106 cells ml−1 (low water, natural site). Moreover, the viral abundance was weakly correlated with chlorophyll a, suggesting that most viruses were bacteriophages. TEM quantitative analyses revealed that the frequency of visibly infected cells was 20%, with 10 ± 3 phages per cell section. In general, we found a low virus-bacterium ratio (<7). Both the close coupling between the viral and bacterial abundances and the low virus-bacterium ratio suggest that viral abundance tends to be driven by the reduction of hosts for viral infection. Our results demonstrate that viruses are controlled by biological substrates, whereas in addition to grazing, bacteria are regulated by physical processes caused by turbidity, which affect underwater light distribution and dissolved organic carbon availability. PMID:20833790

  16. Burdigalian turbid water patch reef environment revealed by larger benthic foraminifera

    NASA Astrophysics Data System (ADS)

    Novak, V.; Renema, W.; Throughflow-project

    2012-04-01

    Ancient isolated patch reefs outcropping from siliciclastic sediments are a trademark for the Miocene carbonate deposits occurring in East Kalimantan, Indonesia. They develop in transitional shelf sediments deposited between deltaic and deep marine deposits (Allen and Chambers, 1998). The Batu Putih Limestone (Wilson, 2005) and similar outcrops in adjacent areas have been characterized as shallow water carbonates influenced by high siliciclastic input, showing low relief patch reefs in turbid waters. Larger benthic foraminifera (LBF) are excellent markers for biochronology and paleoenvironmental reconstruction. This study aims to reveal age and paleoenvironment of a shallow water carbonate patch reef developed in mixed depositional system by using LBF and microfacies analysis. The studied section is located near Bontang, East Kalimantan, and is approximately 80 m long and 12 m high. It is placed within Miocene sediments in the central part of the Kutai Basin. Patch reef and capping sediments were logged through eight transects along section and divided into nine different lithological units from which samples were collected. Thin sections and isolated specimens of larger benthic foraminifera were analyzed and recognized to species level (where possible) providing age and environmental information. Microfacies analysis of thin sections included carbonate classification (textural scheme of Dunham, 1962) and assemblage composition of LBF, algae and corals relative abundance. Three environmentally indicative groups of LBF were separated based on test morphology, habitat or living relatives (Hallock and Glenn, 1986). Analysed foraminifera assemblage suggests Burdigalian age (Tf1). With use of microfacies analysis nine successive lithological units were grouped into five facies types. Paleoenvironmental reconstruction of LBF fossil assemblage indicate two cycles of possible deepening recorded in the section. Based on high muddy matrix ratio in analyzed thin-sections we

  17. Are viruses important in the plankton of highly turbid glacier-fed lakes?

    PubMed Central

    Drewes, Fabian; Peter, Hannes; Sommaruga, Ruben

    2016-01-01

    Viruses are ubiquitous in aquatic ecosystems where they significantly contribute to microbial mortality. In glacier-fed turbid lakes, however, viruses not only encounter low host abundances, but also a high number of suspended mineral particles introduced by glacier meltwaters. We hypothesized that these particles potentially lead to unspecific adsorption and removal of free virus from the plankton, and thus significantly reduce their abundance in this type of lake. We followed the distribution of free virus-like particles (VLP) during the ice-free season across a turbidity gradient in four alpine lakes including one adjacent clear system where hydrological connectivity to the receding glacier is already lost. In the glacier-fed turbid lakes, VLP abundance increased with distance to the glacier, but the highest numbers were observed in the clear lake by the end of August, coinciding with the maximum in prokaryotic abundance. Our results suggest that viral loss by attachment to particles is less important than expected. Nevertheless, the relatively lower variability in VLP abundance and the lower virus-to-prokaryote ratio found in the turbid lakes than in the clear one point to a rather low temporal turnover and thus, to a reduced impact on microbial communities. PMID:27094854

  18. Turbidity-based sediment monitoring in northern Thailand: Hysteresis, variability, and uncertainty

    EPA Science Inventory

    Annual total suspended solid (TSS) loads in the Mae Sa Catchment in northern Thailand, determined with an automated, turbidity-based monitoring approach, were approximately 62,000, 33,000, and 14,000 Mg during the three years of observation. These loads were equivalent to basin y...

  19. UV-induced DNA damage in Cyclops abyssorum tatricus populations from clear and turbid alpine lakes

    PubMed Central

    Tartarotti, Barbara; Saul, Nadine; Chakrabarti, Shumon; Trattner, Florian; Steinberg, Christian E. W.; Sommaruga, Ruben

    2014-01-01

    Zooplankton from clear alpine lakes thrive under high levels of solar UV radiation (UVR), but in glacially turbid ones they are more protected from this damaging radiation. Here, we present results from experiments done with Cyclops abyssorum tatricus to assess UV-induced DNA damage and repair processes using the comet assay. Copepods were collected from three alpine lakes of differing UV transparency ranging from clear to glacially turbid, and exposed to artificial UVR. In addition, photoprotection levels [mycosporine-like amino acids (MAAs) and lipophilic antioxidant capacity] were estimated in the test populations. Similar UV-induced DNA damage levels were observed among the copepods from all lakes, but background DNA damage (time zero and dark controls) was lowest in the copepods from the glacially turbid lake, resulting in a higher relative DNA damage accumulation. Most DNA strand breaks were repaired after recovery in the dark. Low MAA concentrations were found in the copepods from the glacially turbid lake, while the highest levels were observed in the population from the most UV transparent lake. However, the highest lipophilic antioxidant capacities were measured in the copepods from the lake with intermediate UV transparency. Photoprotection and the ability to repair DNA damage, and consequently reducing UV-induced damage, are part of the response mechanisms in zooplankton to changes in water transparency caused by glacier retreat. PMID:24616551

  20. Daily variations in effluent water turbidity and diarrhoeal illness in a Russian city.

    PubMed

    Egorov, Andrey I; Naumova, Elena N; Tereschenko, Andrey A; Kislitsin, Victor A; Ford, Timothy E

    2003-03-01

    To assess an association between temporal variations in drinking water quality and gastrointestinal (GI) illness, a cohort study involving 100 randomly selected families (367 individuals) was conducted in the city of Cherepovets, Russia from June through November 1999. Participants maintained daily diaries of gastrointestinal symptoms, water consumption and other behavioural exposure variables, while daily effluent water quality data were provided by the water utility. The cumulative incidence rate of self-reported gastrointestinal diseases, 1.7 cases per person-year, was almost two orders of magnitude higher than that of officially reported GI infections in the city. An interquartile range increase in effluent water turbidity of 0.8 Nephelometric Turbidity Units was associated with a relative risk of self-reported GI illness of 1.47 (95% Confidence Interval 1.16, 1.86) at a lag of 2 days after control for daily rate of consumption of non-boiled tap water, behavioural covariates, day of the week and a seasonally-related linear trend. In the analysis by subsets of study participants stratified by non-boiled tap water consumption, no statistically significant associations between turbidity and GI illness were found for the study participants who always boiled their drinking water. For individuals who drank non-boiled tap water, statistically significant associations between turbidity and GI illness were detected at lags 1, 2 and 7 days.

  1. Precision cleaning verification of nonvolatile residues by using water, ultrasonics, and turbidity analyses

    NASA Astrophysics Data System (ADS)

    Skinner, S. Ballou

    1991-11-01

    Chlorofluorocarbons (CFC's) in the atmosphere are believed to present a major environmental problem because they are able to interact with and deplete the ozone layer. NASA has been mandated to replace chlorinated solvents in precision cleaning, cleanliness verification, and degreasing of aerospace fluid systems hardware and ground support equipment. KSC has a CFC phase-out plan which provides for the elimination of over 90 percent of the CFC and halon use by 1995. The Materials Science Laboratory and KSC is evaluating four analytical methods for the determination of nonvolatile residues removal by water: (1) infrared analyses using an attenuated total reflectance; (2) surface tension analyses, (3) total organic content analyses, and (4) turbidity analyses. This research project examined the ultrasonic-turbidity responses for 22 hydrocarbons in an effect to determine: (1) if ultrasonics in heated water (70 C) will clean hydrocarbons (oils, greases, gels, and fluids) from aerospace hardware; (2) if the cleaning process by ultrasonics will simultaneously emulsify the removed hydrocarbons in the water; and (3) if a turbidimeter can be used successfully as an analytical instrument for quantifying the removal of hydrocarbons. Sixteen of the 22 hydrocarbons tested showed that ultrasonics would remove it at least 90 percent of the contaminated hydrocarbon from the hardware in 10 minutes or less giving a good ultrasonic-turbidity response. Six hydrocarbons had a lower percentage removal, a slower removal rate, and a marginal ultrasonic-turbidity response.

  2. The role of wind in generating turbidity maxima in the Tay Estuary

    NASA Astrophysics Data System (ADS)

    Weir, D. J.; McManus, J.

    1987-11-01

    Variations of wind direction and strength in the Tay Estuary control wave generation and the resultant patterns of suspended sediment concentration in the waters over the extensive tidal flats. Bodies of water with high water concentration peaks advect to occupy sites at which turbidity maxima are normally present at low water. Other low water peaks are generated by ebb tidal current resuspension.

  3. Copepods in turbid shallow soda lakes accumulate unexpected high levels of carotenoids.

    PubMed

    Schneider, Tobias; Herzig, Alois; Koinig, Karin A; Sommaruga, Ruben

    2012-01-01

    Carotenoids are protective pigments present in many aquatic organisms that reduce the photooxidative stress induced by short-wavelenght solar radiation, yet increase their susceptibility to predators. Arctodiaptomus spinosus, a calanoid copepod typically found in many fishless shallow soda lakes, shows large between-lake differences in pigmentation. Here, we attribute these differences to the environmental state of these ecosystems, namely, 'dark water' lakes with submersed vegetation and turbid 'white' lakes lacking macrophytes. Copepod carotenoid concentration in the turbid 'white' lakes was significantly (about 20-fold) higher than in the 'dark water' ones, although the latter systems were characterized by higher transparency. In addition, males had on a dry weight basis around three times higher carotenoid concentrations than females. Mycosporine-like amino acids (direct UV screening substances) were found in all cases, but in low concentration. The environmental conditions in these ecosystems were largely shaped by the presence/absence of submersed macrophytes Thus, in the turbid lakes, the strong wind-driven mixis allows for copepods to be brought to the surface and being exposed to solar radiation, whereas in 'dark water' ones, macrophytes reduce water turbulence and additionally provide shelter. Our results explain the counter-intuitive notion of strong red pigmentation in copepods from a turbid ecosystem and suggest that factors other than high UV transparency favor carotenoid accumulation in zooplankton.

  4. Turbidity alters pre-mating social interactions between native and invasive stream fishes

    USGS Publications Warehouse

    Glotzbecker, Gregory J.; Ward, Jessica L.; Walters, David M.; Blum, Michael J.

    2015-01-01

    These findings suggest that elevated turbidity can increase pre-mating social interactions between native and invasive species, which could result in greater hybridisation and promote the genetic assimilation of native species following species introductions. Thus, integrating knowledge of species behaviour into conservation and management planning can help deter the establishment and spread of invasive species.

  5. Copepods in Turbid Shallow Soda Lakes Accumulate Unexpected High Levels of Carotenoids

    PubMed Central

    Schneider, Tobias; Herzig, Alois; Koinig, Karin A.; Sommaruga, Ruben

    2012-01-01

    Carotenoids are protective pigments present in many aquatic organisms that reduce the photooxidative stress induced by short-wavelenght solar radiation, yet increase their susceptibility to predators. Arctodiaptomus spinosus, a calanoid copepod typically found in many fishless shallow soda lakes, shows large between-lake differences in pigmentation. Here, we attribute these differences to the environmental state of these ecosystems, namely, ‘dark water’ lakes with submersed vegetation and turbid ‘white’ lakes lacking macrophytes. Copepod carotenoid concentration in the turbid ‘white’ lakes was significantly (about 20-fold) higher than in the ‘dark water’ ones, although the latter systems were characterized by higher transparency. In addition, males had on a dry weight basis around three times higher carotenoid concentrations than females. Mycosporine-like amino acids (direct UV screening substances) were found in all cases, but in low concentration. The environmental conditions in these ecosystems were largely shaped by the presence/absence of submersed macrophytes Thus, in the turbid lakes, the strong wind-driven mixis allows for copepods to be brought to the surface and being exposed to solar radiation, whereas in ‘dark water’ ones, macrophytes reduce water turbulence and additionally provide shelter. Our results explain the counter-intuitive notion of strong red pigmentation in copepods from a turbid ecosystem and suggest that factors other than high UV transparency favor carotenoid accumulation in zooplankton. PMID:22916208

  6. Wavefront analysis of the laser beam propagating through a turbid medium

    SciTech Connect

    Galaktionov, I V; Sheldakova, J V; Kudryashov, A V

    2015-02-28

    Laser beam propagation through a scattering suspension of polystyrene microspheres in distilled water is studied theoretically and experimentally. The dependence of wavefront aberrations on the particle concentration is investigated. The existence of symmetric wavefront aberrations of the laser beam passed through a turbid medium is shown. (light scattering)

  7. Effects on the Mount St. Helens volcanic cloud on turbidity at Ann Arbor, Michigan

    SciTech Connect

    Ryznar, E.; Weber, M.R.; Hallaron, T.S.

    1981-11-01

    Measurements of turbidity were made at the University of Michigan irradiance and metorlogical measurement facility just prior to, during and after the passage of the volcanic cloud from the 18 May 1980 eruption of Mount St. Helens. They were made with a Volz sunphotometer at wavelengths of 500 and 880 nm.

  8. Dynamics of turbidity plumes in Lake Ontario. [Welland Canal and Niagara, Genesee, and Oswego Rivers

    NASA Technical Reports Server (NTRS)

    Pluhowski, E. J. (Principal Investigator)

    1975-01-01

    The author has identified the following significant results. Large turbidity features along the 275 km south shore of Lake Ontario were analyzed using LANDSAT-1 images. The Niagara River plume, ranging from 30 to 500 sq km in area is, by far, the largest turbidity feature in the lake. Based on image tonal comparisons, turbidity in the Welland Canal is usually higher than that in any other water course discharging into the lake during the shipping season. Less turbid water enters the lake from the Port Dalhousie diversion channel and the Genesee River. Relatively clear water resulting from the deposition of suspended matter in numerous upstream lakes is discharged by the Niagara and Oswego Rivers. Plume analysis corroborates the presence of a prevailing eastward flowing longshore current along the entire south shore. Plumes resulting from beach erosion were detected in the images. Extensive areas of the south shore are subject to erosion but the most severely affected beaches are situated between Fifty Mile Point, Ontario and Thirty Mile Point, New York along the Rochester embayment, and between Sodus Bay and Nine Mile Point.

  9. 40 CFR 141.561 - What happens if my system's turbidity monitoring equipment fails?

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 23 2011-07-01 2011-07-01 false What happens if my system's turbidity monitoring equipment fails? 141.561 Section 141.561 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) WATER PROGRAMS (CONTINUED) NATIONAL PRIMARY DRINKING WATER REGULATIONS Enhanced Filtration...

  10. 40 CFR 141.560 - Is my system subject to individual filter turbidity requirements?

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... AGENCY (CONTINUED) WATER PROGRAMS (CONTINUED) NATIONAL PRIMARY DRINKING WATER REGULATIONS Enhanced Filtration and Disinfection-Systems Serving Fewer Than 10,000 People Individual Filter Turbidity Requirements... H system serving fewer than 10,000 people and utilizing conventional filtration or direct...

  11. 40 CFR 141.561 - What happens if my system's turbidity monitoring equipment fails?

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 24 2013-07-01 2013-07-01 false What happens if my system's turbidity monitoring equipment fails? 141.561 Section 141.561 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) WATER PROGRAMS (CONTINUED) NATIONAL PRIMARY DRINKING WATER REGULATIONS Enhanced Filtration...

  12. 40 CFR 141.561 - What happens if my system's turbidity monitoring equipment fails?

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 24 2012-07-01 2012-07-01 false What happens if my system's turbidity monitoring equipment fails? 141.561 Section 141.561 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) WATER PROGRAMS (CONTINUED) NATIONAL PRIMARY DRINKING WATER REGULATIONS Enhanced Filtration...

  13. 40 CFR 141.560 - Is my system subject to individual filter turbidity requirements?

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... AGENCY (CONTINUED) WATER PROGRAMS (CONTINUED) NATIONAL PRIMARY DRINKING WATER REGULATIONS Enhanced Filtration and Disinfection-Systems Serving Fewer Than 10,000 People Individual Filter Turbidity Requirements... H system serving fewer than 10,000 people and utilizing conventional filtration or direct...

  14. 40 CFR 141.561 - What happens if my system's turbidity monitoring equipment fails?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 22 2010-07-01 2010-07-01 false What happens if my system's turbidity monitoring equipment fails? 141.561 Section 141.561 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) WATER PROGRAMS (CONTINUED) NATIONAL PRIMARY DRINKING WATER REGULATIONS Enhanced Filtration...

  15. 40 CFR 141.560 - Is my system subject to individual filter turbidity requirements?

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... AGENCY (CONTINUED) WATER PROGRAMS (CONTINUED) NATIONAL PRIMARY DRINKING WATER REGULATIONS Enhanced Filtration and Disinfection-Systems Serving Fewer Than 10,000 People Individual Filter Turbidity Requirements... H system serving fewer than 10,000 people and utilizing conventional filtration or direct...

  16. 40 CFR 141.561 - What happens if my system's turbidity monitoring equipment fails?

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 23 2014-07-01 2014-07-01 false What happens if my system's turbidity monitoring equipment fails? 141.561 Section 141.561 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) WATER PROGRAMS (CONTINUED) NATIONAL PRIMARY DRINKING WATER REGULATIONS Enhanced Filtration...

  17. 40 CFR 141.560 - Is my system subject to individual filter turbidity requirements?

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... AGENCY (CONTINUED) WATER PROGRAMS (CONTINUED) NATIONAL PRIMARY DRINKING WATER REGULATIONS Enhanced Filtration and Disinfection-Systems Serving Fewer Than 10,000 People Individual Filter Turbidity Requirements... H system serving fewer than 10,000 people and utilizing conventional filtration or direct...

  18. 40 CFR 141.560 - Is my system subject to individual filter turbidity requirements?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... AGENCY (CONTINUED) WATER PROGRAMS (CONTINUED) NATIONAL PRIMARY DRINKING WATER REGULATIONS Enhanced Filtration and Disinfection-Systems Serving Fewer Than 10,000 People Individual Filter Turbidity Requirements... H system serving fewer than 10,000 people and utilizing conventional filtration or direct...

  19. Study of the effect of scattering from turbid water on the polarization of a laser beam

    NASA Technical Reports Server (NTRS)

    Henderson, R. G.; Hovanlou, A. H.

    1978-01-01

    A Monte Carlo simulation method was used to determine the effect of scattering from turbid water on the polarization of a backscattered beam of laser light. The relationship between the polarization and the type and amount of suspended particulates in the water was investigated.

  20. A non-stochastic iterative computational method to model light propagation in turbid media

    NASA Astrophysics Data System (ADS)

    McIntyre, Thomas J.; Zemp, Roger J.

    2015-03-01

    Monte Carlo models are widely used to model light transport in turbid media, however their results implicitly contain stochastic variations. These fluctuations are not ideal, especially for inverse problems where Jacobian matrix errors can lead to large uncertainties upon matrix inversion. Yet Monte Carlo approaches are more computationally favorable than solving the full Radiative Transport Equation. Here, a non-stochastic computational method of estimating fluence distributions in turbid media is proposed, which is called the Non-Stochastic Propagation by Iterative Radiance Evaluation method (NSPIRE). Rather than using stochastic means to determine a random walk for each photon packet, the propagation of light from any element to all other elements in a grid is modelled simultaneously. For locally homogeneous anisotropic turbid media, the matrices used to represent scattering and projection are shown to be block Toeplitz, which leads to computational simplifications via convolution operators. To evaluate the accuracy of the algorithm, 2D simulations were done and compared against Monte Carlo models for the cases of an isotropic point source and a pencil beam incident on a semi-infinite turbid medium. The model was shown to have a mean percent error less than 2%. The algorithm represents a new paradigm in radiative transport modelling and may offer a non-stochastic alternative to modeling light transport in anisotropic scattering media for applications where the diffusion approximation is insufficient.

  1. Imaging quality comparison of two typical methods for imaging through turbid media

    NASA Astrophysics Data System (ADS)

    Shao, Xiaopeng; Wu, Tengfei; Gong, Changmei

    2014-06-01

    Due to the multiple scattering of light in turbid media such as biological tissues, the image of target becomes highly deteriorated and even disappears entirely. Only speckle patterns, which result from multiple scattering and interference in turbid media and contain disordered objects-information, can be acquired. Two typical methods to recover the image of target behind a turbid medium are described and simulated in this paper. The first approach is based on image correlation and wavefront shaping technique, in which the Pearson correlation coefficient is applied as a cost function for the optimization and genetic algorithm (GA) is employed to control a spatial light modulator to generate the optimal wavefront to maximize the cost function. For the second approach, the target images can be reconstructed from the speckle patterns with total variation minimization by augmented Lagrangian and alternating direction algorithms (TVAL3). Circular Gaussian distribution model and Fresnel diffraction theory are exploited in our simulations to describe turbid media and light propagation between optical devices, respectively. The anti-noise capabilities of the two methods are analyzed to demonstrate their stabilities applied in low signal-to-noise environment. This work will be beneficial to the fields of microscopic imaging and biomedical imaging in micro/nano scale.

  2. Turbidimeter Design and Analysis: A Review on Optical Fiber Sensors for the Measurement of Water Turbidity

    PubMed Central

    Omar, Ahmad Fairuz Bin; MatJafri, Mohd Zubir Bin

    2009-01-01

    Turbidimeters operate based on the optical phenomena that occur when incident light through water body is scattered by the existence of foreign particles which are suspended within it. This review paper elaborates on the standards and factors that may influence the measurement of turbidity. The discussion also focuses on the optical fiber sensor technologies that have been applied within the lab and field environment and have been implemented in the measurement of water turbidity and concentration of particles. This paper also discusses and compares results from three different turbidimeter designs that use various optical components. Mohd Zubir and Bashah and Daraigan have introduced a design which has simple configurations. Omar and MatJafri, on the other hand, have established a new turbidimeter design that makes use of optical fiber cable as the light transferring medium. The application of fiber optic cable to the turbidimeter will present a flexible measurement technique, allowing measurements to be made online. Scattered light measurement through optical fiber cable requires a highly sensitive detector to interpret the scattered light signal. This has made the optical fiber system have higher sensitivity in measuring turbidity compared to the other two simple turbidimeters presented in this paper. Fiber optic sensors provide the potential for increased sensitivity over large concentration ranges. However, many challenges must be examined to develop sensors that can collect reliable turbidity measurements in situ. PMID:22408507

  3. Are viruses important in the plankton of highly turbid glacier-fed lakes?

    NASA Astrophysics Data System (ADS)

    Drewes, Fabian; Peter, Hannes; Sommaruga, Ruben

    2016-04-01

    Viruses are ubiquitous in aquatic ecosystems where they significantly contribute to microbial mortality. In glacier-fed turbid lakes, however, viruses not only encounter low host abundances, but also a high number of suspended mineral particles introduced by glacier meltwaters. We hypothesized that these particles potentially lead to unspecific adsorption and removal of free virus from the plankton, and thus significantly reduce their abundance in this type of lake. We followed the distribution of free virus-like particles (VLP) during the ice-free season across a turbidity gradient in four alpine lakes including one adjacent clear system where hydrological connectivity to the receding glacier is already lost. In the glacier-fed turbid lakes, VLP abundance increased with distance to the glacier, but the highest numbers were observed in the clear lake by the end of August, coinciding with the maximum in prokaryotic abundance. Our results suggest that viral loss by attachment to particles is less important than expected. Nevertheless, the relatively lower variability in VLP abundance and the lower virus-to-prokaryote ratio found in the turbid lakes than in the clear one point to a rather low temporal turnover and thus, to a reduced impact on microbial communities.

  4. Precision Cleaning Verification of Nonvolatile Residues by Using Water, Ultrasonics, and Turbidity Analyses

    NASA Technical Reports Server (NTRS)

    Skinner, S. Ballou

    1991-01-01

    Chlorofluorocarbons (CFC's) in the atmosphere are believed to present a major environmental problem because they are able to interact with and deplete the ozone layer. NASA has been mandated to replace chlorinated solvents in precision cleaning, cleanliness verification, and degreasing of aerospace fluid systems hardware and ground support equipment. KSC has a CFC phase-out plan which provides for the elimination of over 90 percent of the CFC and halon use by 1995. The Materials Science Laboratory and KSC is evaluating four analytical methods for the determination of nonvolatile residues removal by water: (1) infrared analyses using an attenuated total reflectance; (2) surface tension analyses, (3) total organic content analyses, and (4) turbidity analyses. This research project examined the ultrasonic-turbidity responses for 22 hydrocarbons in an effect to determine: (1) if ultrasonics in heated water (70 C) will clean hydrocarbons (oils, greases, gels, and fluids) from aerospace hardware; (2) if the cleaning process by ultrasonics will simultaneously emulsify the removed hydrocarbons in the water; and (3) if a turbidimeter can be used successfully as an analytical instrument for quantifying the removal of hydrocarbons. Sixteen of the 22 hydrocarbons tested showed that ultrasonics would remove it at least 90 percent of the contaminated hydrocarbon from the hardware in 10 minutes or less giving a good ultrasonic-turbidity response. Six hydrocarbons had a lower percentage removal, a slower removal rate, and a marginal ultrasonic-turbidity response.

  5. Gill structural change in response to turbidity has no effect on the oxygen uptake of a juvenile sparid fish

    PubMed Central

    Cumming, H.; Herbert, N. A.

    2016-01-01

    Turbidity as a result of increased suspended sediments in coastal waters is an environmental stress of worldwide concern. Recent research on fish suggests that detrimental changes to gill structure can occur in turbid waters, with speculation that these alterations diminish fitness variables, such as growth and development, by negatively impacting the O2 uptake capacity (respiration) of fish. Specifically to address this unknown, the impact of turbid water on the gill structure, somatic growth rate and O2 uptake rates of a juvenile sparid species (Pagrus auratus) was addressed following exposure to five different turbidity treatments (<10, 20, 40, 60 or 80 nephelometric turbidity units) for 30 days. Significant gill structural change was apparent with a progressive increase in turbidity and was quantified as a reduction in lamellar density, as well as an increase in basal hyperplasia, epithelial lifting and increased oxygen diffusion distance across the lamellae. The weight of control fish did not change throughout the experiment, but all fish exposed to turbid waters lost weight, and weight loss increased with nephelometric turbidity units, confirming that long-term turbidity exposure is detrimental to growth productivity. The growth of fish could be impacted in a variety of ways, but the specific hypothesis that structural alteration of the gills impairs O2 uptake across the gills and limits growth fitness was not supported because there was no measurable difference in the standard metabolic rate, maximal metabolic rate, aerobic metabolic scope or critical oxygen saturation limit of fish measured in clear water after 30 days of exposure. Although impaired O2 uptake as a result of structurally adjusted gills is unlikely to be the cause of poor fish growth, the exact mechanism by which growth productivity is affected in turbid conditions remains unclear and warrants further investigation. PMID:27766155

  6. Are stream stabilization projects reducing suspended sediment concentrations and turbidity in the New York City Water Supply Watershed?

    NASA Astrophysics Data System (ADS)

    McHale, M. R.; Siemion, J.; Davis, W. D.

    2015-12-01

    Turbidity and suspended sediment concentrations (SSCs) are primary water quality concerns in the upper Esopus Creek watershed, the main tributary to the Ashokan reservoir. The Ashokan reservoir is one of 6 surface water reservoirs that constitute about 90% of New York City's drinking water supply. This study quantified turbidity levels and SSCs at 10 locations throughout the upper Esopus Creek watershed for 3 years prior to the implementation of 2 stream stabilization projects and for 18 months after the projects were completed. More than 93 percent of the total-suspended sediment load occurred on days with flows greater than or equal to the 90th percentile of flows observed during the study period. Discharge, SSC, and turbidity were strongly related at the outlet of the upper Esopus Creek, but not at every monitoring site. In general, relations between discharge and SSC and turbidity were strongest at sites with high SSCs, with the exception of Stony Clove Creek, the largest tributary. Stony Clove Creek, consistently produced higher SSCs and turbidity than any of the other Esopus Creek tributaries. Nonetheless, there was not a strong relation between either turbidity or SSC and discharge because there was a series of eroding banks in contact with fine grained glacio-lacustrine deposits and associated hill slope failures within the Stony Clove Creek watershed that delivered elevated turbidity and SSCs to the stream during all flow conditions. Stream bank stabilization projects were completed at two of the largest bank failures. After the projects were completed there was decrease in stream SSC and turbidity however, flows during the 18 months following the projects were lower than before the projects. Nevertheless, a shift in the SSC and turbidity discharge rating curves suggests that the stream stabilization projects resulted in lower turbidity levels and SSCs for similar discharge conditions as compared to before the projects thereby reducing sediment yields

  7. Drinking Water Turbidity and Emergency Department Visits for Gastrointestinal Illness in New York City, 2002-2009

    PubMed Central

    Hsieh, Jennifer L.; Nguyen, Trang Quyen; Matte, Thomas; Ito, Kazuhiko

    2015-01-01

    Background Studies have examined whether there is a relationship between drinking water turbidity and gastrointestinal (GI) illness indicators, and results have varied possibly due to differences in methods and study settings. Objectives As part of a water security improvement project we conducted a retrospective analysis of the relationship between drinking water turbidity and GI illness in New York City (NYC) based on emergency department chief complaint syndromic data that are available in near-real-time. Methods We used a Poisson time-series model to estimate the relationship of turbidity measured at distribution system and source water sites to diarrhea emergency department (ED) visits in NYC during 2002-2009. The analysis assessed age groups and was stratified by season and adjusted for sub-seasonal temporal trends, year-to-year variation, ambient temperature, day-of-week, and holidays. Results Seasonal variation unrelated to turbidity dominated (~90% deviance) the variation of daily diarrhea ED visits, with an additional 0.4% deviance explained with turbidity. Small yet significant multi-day lagged associations were found between NYC turbidity and diarrhea ED visits in the spring only, with approximately 5% excess risk per inter-quartile-range of NYC turbidity peaking at a 6 day lag. This association was strongest among those aged 0-4 years and was explained by the variation in source water turbidity. Conclusions Integrated analysis of turbidity and syndromic surveillance data, as part of overall drinking water surveillance, may be useful for enhanced situational awareness of possible risk factors that can contribute to GI illness. Elucidating the causes of turbidity-GI illness associations including seasonal and regional variations would be necessary to further inform surveillance needs. PMID:25919375

  8. The dependence of estuarine turbidity on tidal intrusion length, tidal range and residence time

    USGS Publications Warehouse

    Uncles, R.J.; Stephens, J.A.; Smith, R.E.

    2002-01-01

    It is shown that there is a marked tendency for long, strongly tidal estuaries to have greater suspended particulate matter (SPM) concentrations within their high-turbidity regions than shorter estuaries with comparable tidal ranges at their mouths, or weakly tidal estuaries. Using consistently derived data from 44 estuaries in Europe and the Americas, contours of the logarithm of maximum estuarine SPM concentration are shown to be reasonably smooth when plotted against the logarithm of mean spring tidal range (at the estuary mouth) and the logarithm of estuarine tidal length. Predictions from the plot are compared with published observations made in the Delaware, Scheldt, Rio de la Plata, Gironde, Bay of Fundy, Changjiang (Yangtze), Amazon, Paros Lagoon and the Hawkesbury Estuary and it is shown that, qualitatively, there are no serious discrepancies. Short, weakly tidal estuaries are predicted to have very low 'intrinsic' SPM concentrations. High SPM concentrations in these estuaries would most likely be the result of either locally generated wave resuspension, high freshwater sediment loads due to freshets, or intruding seawater carrying suspended sediments derived from wave activity in the coastal zone. Application of a generic tidal model demonstrates that longer estuaries possess faster tidal currents for a given tidal range at their mouth and, in the presence of a supply of erodable fine sediment, therefore (by implication) produce greater concentrations of SPM that can be accumulated within a turbidity maximum. The same is true if the tidal range is increased for estuaries of a given length. These features are illustrated by comparing surveys of SPM data from two large estuaries possessing greatly different tidal ranges (the microtidal, medium turbidity Potomac and the macrotidal, highly turbid Humber-Ouse) and a third, much smaller but strongly tidal estuary (the low-turbidity Tweed). It is demonstrated that longer estuaries tend to have longer flushing

  9. A new model for marine density-turbidity currents with criteria for ignition

    NASA Astrophysics Data System (ADS)

    Salusti, E.

    We discuss the hydrodynamic stability properties of a one-dimensional quasi-steady marine current, driven by a density excess caused by low temperature or high salinity, and flowing over a regular slope, taking bottom-erosion phenomena into consideration. The term density-turbidity current is used here for a thermohaline density current, with that density increased by entrained sediment. Thermohaline currents are of fundamental importance with regard to the Earth's climate, and the same must apply to density-turbidity currents. To simplify this complex problem, we schematize the flow as a thin turbulent quasisteady current, with gravitational and frictional forces in approximate equilibrium; the effects of small-scale perturbations, and of interaction with the bottom sediment, are then schematised by assuming a heuristic model of sediment evolution. Indeed, as in recent work by Caserta et al. (1990), we postulate that density variation due to bottom erosion or deposition is a function only of the shear stress exerted on the sea bottom by the current. Using these assumptions, we arrive at a complex nonlinear equation which considers both time and space variability for a realistic two-layer model of these density-turbidity currents. This finally gives a nonlinear heat equation that displays both diffusive behaviour and a peculiar type of time-delayed nonlinear behaviour, a previously-unrecognised effect governed by a criterion which defines explosive perturbations. It is of interest that this criterion is not related to energy considerations, like other criteria discussed in the literature, but is based on hydrodynamic instability considerations. The above model can also be applied to classical turbidity currents, i.e. those in which the interstitial fluid has the same density as the ambient fluid. However, the way in which the initial turbid water is generated is of paramount importance; mechanisms include submarine slumping, underflows from large flooded rivers

  10. Evaluation of using aluminum sulfate and water-soluble Moringa oleifera seed lectin to reduce turbidity and toxicity of polluted stream water.

    PubMed

    Freitas, José Henrique Edmilson Souza; de Santana, Keissy Vanderley; do Nascimento, Ana Cláudia Claudina; de Paiva, Sérgio Carvalho; de Moura, Maiara Celine; Coelho, Luana Cassandra Breitenbach Barroso; de Oliveira, Maria Betânia Melo; Paiva, Patrícia Maria Guedes; do Nascimento, Aline Elesbão; Napoleão, Thiago Henrique

    2016-11-01

    Aluminum salts are used as coagulants in water treatment; however, the exposure to residual aluminum has been associated with human brain lesions. The water-soluble Moringa oleifera lectin (WSMoL), which is extracted with distilled water and isolated by chitin chromatography, has coagulant activity and is able to reduce the concentration of metal ions in aqueous solutions. This study evaluated the potential of using aluminum sulfate and WSMoL to reduce the turbidity and toxicity of water from the Cavouco stream located in Recife, Pernambuco, Brazil. The water sample used (called P1) was collected from the stream source, which was found to be strongly polluted based on physicochemical and water quality analyses, as well as ecotoxicity assays with Artemia salina and seeds of Eruca sativa and Lactuca sativa. The assays combining WSMoL and aluminum sulfate were more efficient than those that used these agents separately. Furthermore, the greatest reduction in turbidity (96.8%) was obtained with the treatment using aluminum sulfate followed by WSMoL, compared to when they were applied simultaneously (91.3%). In addition, aluminum sulfate followed by WSMoL treatment resulted in residual aluminum concentration (0.3 mg/L) that was much lower than that recorded after the treatment using only the salt (35.5 mg/L). The ecotoxicity of P1 was also strongly reduced after the treatments. In summary, the combined use of aluminum sulfate and WSMoL was efficient in promoting a strong reduction of turbidity and ecotoxicity of a polluted water sample, without resulting in a high residual aluminum concentration at the conclusion of the treatment.

  11. Retrieval of Water Quality Parameters in a Highly Turbid Estuary from Hyperspectral Remote Sensing Imagery

    NASA Astrophysics Data System (ADS)

    Hestir, E. L.; Greenberg, J. A.; Ustin, S. L.

    2007-12-01

    The Sacramento-San Joaquin River Delta is a highly turbid inland estuary that drains into the Pacific Ocean via the San Francisco Bay. The Delta has become a major ecological concern over the past decade, and the decline of the endangered fish, Delta smelt, has been attributed in part to decreasing turbidity in the Delta. Measuring and monitoring turbidity and Secchi disk depth are important to ecosystem health management and water quality monitoring of inland case-2 waters. The spectral determination of water quality parameters is dependent on (i) the inherent optical properties of water, such as the load of total suspended solids, suspended sediments, humic acids and dissolved organic matter, and planktonic content and composition, and (ii) the apparent optical properties of water which depend on both the medium and the geometric structure of light (surface reflectance, vertical diffuse attenuation). Water quality parameters such as turbidity and Secchi disk depth can be retrieved from hyperspectral remote sensing imagery, remote sensing data collected with many narrow spectral bands, using semi-empirical methods that require regression analysis, or from radiative transfer calculations that model apparent optical properties. We compared the accuracy of both semi-empirical and radiative transfer methods to retrieve turbidity and Secchi disk depths from airborne hyperspectral remote sensing imagery (the HyMap sensor, 450-2500 nm, 10-15nm bandwidth) of the Delta collected in June 2007. Results were validated using extensive field data collected concurrent with image acquisition. Additionally, we examined the effect of resampling the hyperspectral data to multispectral resolutions more commonly found on spaceborne instruments on the accuracy of water constituent retrieval from inland, case-2 waters.

  12. Direct measurements by submersible of surge-type turbidity currents in a fjord channel, southeast Alaska

    SciTech Connect

    Cowan, E.A. . Dept. of Geology); Powell, R.D. . Geology Dept.); Lawson, D.E. ); Carlson, P.R. )

    1992-01-01

    High density, high-speed turbidity currents were observed and their properties measured in submarine channels in Queen Inlet, southeast Alaska during June, 1990 and 1991. A ROV submersible fitted with two video cameras, a CTD, an optical backscatter turbidity monitor (OBS), and electromagnetic current meter, and sidescan sonar was used to collect data from within and above the flows. Multiple flows were recorded during a ROV dive at 2.3 km from the delta front in a channel at 104 m depth. Flows were marked by sudden increases in turbidity and current velocity. In one flow, turbidity increased from 300 to 1,600 OBS units (instrument maximum) in 10 sec, and within 9.4 min, salinity (S) steadily decreased by 12.1 ppt, with only a 0.2 C temperature (T) increase. Density differences between the flow and ambient water require a minimum sediment concentration of 97 g/l. Maximum flow velocity exceeded 3.3 m/s. A vertical ROV profile indicated a flow thickness of 10 m. The upper surface was visually identified by billowing suspended sediment and by fluctuating OBS and T as ambient and flow water mixed in turbulent eddies. A faster S decrease and slower T increase with distance into and away from the flow indicate that thermal diffusive processes were less efficient than convective mass transfer. The S change indicates that flow water and ambient water mixed well beyond the flow defined by high turbidity. Warm water temperatures within the flow and low meltwater stream discharge suggest that these flows originated from the delta front and are not continuous underflows.

  13. Direct Monitoring of Turbidity Currents: New Insights, Challenging Preconceptions and Future Directions

    NASA Astrophysics Data System (ADS)

    Clare, M. A.; Talling, P. J.; Cartigny, M.; Vardy, M. E.; Azpiroz, M.; Hunt, J.; Sumner, E.; Hizzett, J.; Vellinga, A.; Hughes Clarke, J. E.

    2015-12-01

    Turbidity currents are, volumetrically, the most important process for the transportation of sediment on the face of our planet. The combination of large volume and fast speeds can damage globally important seafloor cables and offshore structures and may transport sediment over hundreds of kilometres. Despite their significance for sediment flux and as geohazards, very few examples of direct monitoring of real-world turbidity currents exist. Until recently, there has been a reliance on depositional records, scaled-down experiments and numerical models to understand the nature of turbidity currents. The results of direct monitoring obtained over the past few years now provide us with ground-breaking insights into the real-world behaviour of full-scale turbidity currents. We present results of recent flow monitoring acquired using an array of acoustic and geophysical tools, from multiple sites worldwide, including the deep-sea Congo Canyon, Canadian fjords, and a dredging experiment offshore Holland. This advent in turbidity current monitoring, largely driven by step-changes in technology, has reinforced some existing interpretations, but also challenges some preconceptions. Our results are based on monitoring using multibeam sonars, sub-bottom and acoustic Doppler current profilers. First, we provide insights into the triggering of flows that include landslides, tidal and wave effects, and other more cryptic events with no clear initiation point. Second, the influence of dense layers at the base of flows is shown to be important for sediment transport and bedform migration; however, most acoustic techniques struggle to penetrate. Initial results from a novel Chirp profiler provide imaging of the lowermost part of the flow. Third, the morphology of the flow and its development through time are shown to deviate from that observed in classical flume tank experiments. Finally, we summarise some future directions for flow monitoring to push forward our understanding of

  14. Nitrification and its oxygen consumption along the turbid Chang Jiang River plume

    NASA Astrophysics Data System (ADS)

    Hsiao, S. S.-Y.; Hsu, T.-C.; Liu, J.-w.; Xie, X.; Zhang, Y.; Lin, J.; Wang, H.; Yang, J.-Y. T.; Hsu, S.-C.; Dai, M.; Kao, S.-J.

    2014-04-01

    Nitrification is a series of processes that oxidizes ammonia to nitrate, which contributes to hypoxia development in coastal oceans, especially in eutrophicated regions. The nitrification rate of bulk water (NRb) and particle free water (NRpf, particle > 3 μm eliminated) were determined along the Chang Jiang River plume in August 2011 by nitrogen isotope tracer technique. Measurements of dissolved oxygen (DO), community respiration rate (CR), nutrients, dissolved organic nitrogen (DON), total suspended matter (TSM), particulate organic carbon/nitrogen (POC / PON), acid-leachable iron and manganese on suspended particles and both archaeal and β-proteobacterial ammonia monooxygenase subunit A gene (amoA) abundance on size-fractioned particles (> 3 μm and 0.22-3 μm) were conducted. The NRb ranged from undetectable up to 4.6 μmol L-1 day-1, peaking at a salinity of ~ 29. NRb values were positively correlated with ammonium concentration, suggesting the importance of substrate in nitrification. In the river mouth and the inner plume, NRb was much higher than NRpf, indicating that the nitrifying microorganism is mainly particle associated, which was supported by its significant correlation with amoA gene abundance and TSM concentration. The estimated oxygen demands of nitrification accounted for 0.32 to 318% of CR, in which 50% samples demanded more oxygen than that predicted by by the Redfield model (23%), indicating that oxygen might not be the sole oxidant though DO was sufficient (> 58 μmol kg-1) throughout the observation period. The excess nitrification-associated oxygen demand (NOD) showed a tendency to occur at lower DO samples accompanied by higher acid-leachable Fe / Mn, which implied reactive Fe3+ / Mn4+ may play a role as oxidant in the nitrification process. Stoichiometric calculation suggested that reactive Fe on particles was 10 times the oxidant demand required to complete ammonia oxidation in the entire plume. The potential involvement of reactive

  15. Modelling the risk of mortality of Corbicula fluminea (Müller, 1774) (Bivalvia: Corbiculidae) exposed to different turbidity conditions.

    PubMed

    Avelar, W E P; Neves, F F; Lavrador, M A S

    2014-05-01

    The provision of sediment in rivers, due to erosion processes that occur in the environment, consists of a major source of pollution and alteration of the physicochemical conditions of water resources. In addition, the increase in water turbidity may cause siltation, dramatically impacting aquatic communities. Specifically considering the bivalve Corbicula fluminea (Müller, 1774), the aim of this study was to analyse the effect of exposure to different turbidity conditions of sediments, as a risk factor for the animals. For this purpose, a docking device was designed to ensure water circulation in a closed system and to maintain the desired levels of turbidity. Although C. fluminea can generally tolerate environmental changes in aquatic systems, an intolerance to high turbidity levels was experimentally observed, expressed by the mortality rate of the animals when exposed to conditions above 150 nephelometric turbidity units (NTU). This value was similar to the one recorded at study sites in the rivers Pardo (Serrana-SP-Brazil) and Mogi Guaçu (Porto Ferreira-SP-Brazil) during the rainy season. Using a logistic regression model, the experimental results were analysed and the observed mortality rates indicate that the exposure of the animals to turbidity levels above 150 nephelometric turbidity units (NTU), for periods longer than 120 hours, may be considered a probable cause of mortality for the species.

  16. Estimation of suspended-sediment concentration from total suspended solids and turbidity data for Kentucky, 1978-1995

    USGS Publications Warehouse

    Williamson, Tanja N.; Crawford, Charles G.

    2011-01-01

    Suspended sediment is a constituent of water quality that is monitored because of concerns about accelerated erosion, nonpoint contamination of water resources, and degradation of aquatic environments. In order to quantify the relationship among different sediment parameters for Kentucky streams, long-term records were obtained from the National Water Information System of the U.S. Geological Survey. Suspended-sediment concentration (SSC), the parameter traditionally measured and reported by the U.S. Geological Survey, was statistically compared to turbidity and total suspended solids (TSS), two parameters that are considered surrogate data. A linear regression of log-transformed observations was used to estimate SSC from TSS; 72% of TSS observations were less than coincident SSC observations; however, the estimated SSC values were almost as likely to be overestimated as underestimated. The SSC-turbidity relationship also used log-transformed observations, but required a nonlinear, breakpoint regression that separated turbidity observations ???6nephelometric turbidity units. The slope for these low turbidity values was not significantly different than zero, indicating that low turbidity observations provide no real information about SSC; in the case of the Kentucky sediment record, this accounts for 30% of the turbidity observations. ?? 2011 American Water Resources Association. This article is a U.S. Government work and is in the public domain in the USA.

  17. Coral assemblages are structured along a turbidity gradient on the Southwestern Gulf of Mexico, Veracruz

    NASA Astrophysics Data System (ADS)

    Jordán-Garza, A. G.; González-Gándara, C.; Salas-Pérez, J. J.; Morales-Barragan, A. M.

    2017-04-01

    Corals on the reef corridor of the southwestern Gulf of Mexico have evolved on a terrigenous shallow continental shelf under the influence of several natural river systems. As a result, water turbidity on these reefs can be high, with visibility as low as <1 m, depending on reef location and season. Using a presence-absence species database from field surveys, literature search, and satellite data on sea surface temperature, turbidity and chlorophyll-a, the coral species composition and environmental variables were analyzed for the three main reef systems of the reef corridor of the southwestern Gulf of Mexico. Completeness of the data set was assessed using species accumulation curves and non-parametric estimators of species richness. Differences in coral assemblages' composition between the reef systems were investigated using univariate (ANOVA) and multivariate (nMDS, ANOSIM, SIMPER) analyses and the relationship between the assemblages and environmental data was assessed using a forward selection process in canonical correspondence analysis (CCA) to eliminate non-significant environmental variables. The northern and central Veracruz reef systems share a similar number of coral species (p=0.78 mult. comp.) and both showed higher species richness than the southern system (p<0.001 mult. comp.). In terms of the assemblages' structure, significant differences were found (ANOSIM R=0.3, p=0.001) with larger average dissimilitude between north-south (75.4% SIMPER) and central-south (74.2%) than north-central (27%) comparisons. Only environmental variables related to water turbidity and productivity were significant on the final CCA configuration, which showed a gradient of increasing turbidity from north to south. Reef geomorphology and the effect of turbidity help explain differences in coral assemblages' composition. More studies are necessary to establish if turbidity could function as a refuge for future environmental stress. Each Veracruz reef system is at the

  18. New turbidity current model based on high-resolution monitoring of the longest flow ever measured

    NASA Astrophysics Data System (ADS)

    Azpiroz, Maria; Cartigny, Matthieu; Talling, Peter; Parsons, Daniel; Simmons, Steve; Clare, Michael; Sumner, Esther; Pope, Ed

    2016-04-01

    Turbidity currents transport large amounts of sediment from shallow waters towards deep ocean basins. Little is known about these flows, despite their potential hazard for damaging expensive and strategically important seafloor infrastructure. So far turbidity currents have been profiled in only 6 deep ocean locations worldwide. Our current knowledge of these flows is therefore mainly based on scaled-down experimental and computationally-limited numerical modelling. Here we present results from the monitoring of a one-week long turbidity current in the Congo Canyon that had a discharge close to that of the Mississippi River. Measurements taken every 5 seconds give the most detailed image yet of a turbidity current deep-water over an unprecedented duration. Our analysis reveals a different flow structure than that presented in previous models. Classical models display a thick front of the flow followed by a thinner and faster flow, which gives way to a short and quasi-steady body. Instead, we observe a thin frontal cell that outruns a thicker (~80 m), long and slower quasi-steady flow. In contrast to the previous model, where the thinner faster flow feeds sediment into the head, the Congo Canyon turbidity current shows a frontal cell that feeds sediment into, and at the same time outruns, the succeeding quasi-steady flow. As a result of the faster moving frontal cell, the flow should continuously stretch and grow in length while propagating down the system. Within the quasi-steady body, the flow switches between what appears to be two stable flow modes. One mode exhibits a fast and thin velocity profile whose maximum is a low distance from the seabed and resembles Froude-supercritical flow conditions, while the other mode is similar to Froude-subcritical flow conditions as the flow is thicker and slower. These first observations provide new insights into the behaviour of deep water long duration flows that differ from traditional models and provide an exciting

  19. Limiting Factors on Image Quality in Imaging through Turbid Media under Single-photon and Two-photon Excitation

    NASA Astrophysics Data System (ADS)

    Schilders, S. P.; Gu, M.

    2000-03-01

    The effect of multiple scattering in a turbid medium on single-photon and two-photon fluorescence microscopy is experimentally investigated for different scattering characteristics including scattering anisotrophy and optical thickness of a turbid medium. It is demonstrated that two-photon excitation can provide significant improvement in penetration depth through turbid media, due to reduced scattering experienced by the excitation beam. It is also shown that the limiting factor in obtaining high-quality images under singlephoton excitation is the fast degradation of image resolution caused by multiple scattering, while for twophoton excitation it is limited by the degradation of image contrast due to the reduction in fluorescence strength.

  20. Speckle contrast diffuse correlation tomography of complex turbid medium flow

    SciTech Connect

    Huang, Chong; Irwin, Daniel; Lin, Yu; Shang, Yu; He, Lian; Kong, Weikai; Yu, Guoqiang; Luo, Jia

    2015-07-15

    Purpose: Developed herein is a three-dimensional (3D) flow contrast imaging system leveraging advancements in the extension of laser speckle contrast imaging theories to deep tissues along with our recently developed finite-element diffuse correlation tomography (DCT) reconstruction scheme. This technique, termed speckle contrast diffuse correlation tomography (scDCT), enables incorporation of complex optical property heterogeneities and sample boundaries. When combined with a reflectance-based design, this system facilitates a rapid segue into flow contrast imaging of larger, in vivo applications such as humans. Methods: A highly sensitive CCD camera was integrated into a reflectance-based optical system. Four long-coherence laser source positions were coupled to an optical switch for sequencing of tomographic data acquisition providing multiple projections through the sample. This system was investigated through incorporation of liquid and solid tissue-like phantoms exhibiting optical properties and flow characteristics typical of human tissues. Computer simulations were also performed for comparisons. A uniquely encountered smear correction algorithm was employed to correct point-source illumination contributions during image capture with the frame-transfer CCD and reflectance setup. Results: Measurements with scDCT on a homogeneous liquid phantom showed that speckle contrast-based deep flow indices were within 12% of those from standard DCT. Inclusion of a solid phantom submerged below the liquid phantom surface allowed for heterogeneity detection and validation. The heterogeneity was identified successfully by reconstructed 3D flow contrast tomography with scDCT. The heterogeneity center and dimensions and averaged relative flow (within 3%) and localization were in agreement with actuality and computer simulations, respectively. Conclusions: A custom cost-effective CCD-based reflectance 3D flow imaging system demonstrated rapid acquisition of dense boundary

  1. Turbidity dynamics during spring storm events in an urban headwater river system: the Upper Tame, West Midlands, UK.

    PubMed

    Lawler, D M; Petts, G E; Foster, I D L; Harper, S

    2006-05-01

    Turbidity is an important water quality variable, through its relation to light suppression, BOD impact, sediment-associated contaminant transport, and suspended sediment effects on organisms and habitats. Yet few published field investigations of wet-weather turbidity dynamics, through several individual and sequenced rainstorms in extremely urbanised headwater basins, have emerged. This paper aims to address this gap through a turbidity analysis of multiple storm events in spring 2001 in an urban headwater basin (57 km2) of the River Tame, central England, the most urbanised basin for its size in the UK ( approximately 42%). Data were collected at 15-min frequency at automated monitoring stations for rainfall, streamflow and six water quality variables (turbidity, EC, temperature, DO, pH, ammonia). Disturbance experiments also allowed estimates of bed sediment storage to be obtained. Six important and unusual features of the storm event turbidity response were apparent: (1) sluggish early turbidity response, followed by a turbidity 'rush'; (2) quasi-coincident flow and turbidity peaks; (3) anti-clockwise hysteresis in the discharge-turbidity relationship on all but one event, resulting from Falling-LImb Turbidity Extensions (FLITEs); (4) increases in peak turbidity levels through storm sequences; (5) initial micro-pulses (IMP) in turbidity; and (6) secondary turbidity peaks (STP) or 'turbidity shoulders' (TS). These features provided very little evidence of a true 'first-flush' effect: instead, substantial suspended solids transport continued right through the flow recessions, and little storm-event sediment exhaustion was evident. A new, dimensionless, hysteresis index, HI(mid), is developed to quantify the magnitude and direction of hysteresis in a simple, clear, direct and intuitive manner. This allowed the degree of departure from the classic 'first-flush', clockwise hysteresis models to be assessed. Of the 15 turbidity events considered, 10 coincided with

  2. Removal of Giardia spp. and Cryptosporidium spp. from water supply with high turbidity: analytical challenges and perspectives.

    PubMed

    Maciel, P M F; Sabogal-Paz, L P

    2016-06-01

    Giardia and Cryptosporidium species are a serious problem if present in water supplies. The removal of these protozoans and the adaptation of existing protocols are essential for supplying drinking water to developing countries. Considering this, the aim of this study is to evaluate, on a bench level, the removal of Giardia spp. cysts and of Cryptosporidium spp. oocysts from water with high turbidity, using polyaluminium chloride as a coagulant. Filtration using mixed cellulose ester membranes, followed, or not, by purification through immunomagnetic separation (IMS) was used for detecting protozoans. By evaluating the adopted protocol, without using IMS, retrievals of 80% of cysts and 5% of oocysts were obtained, whereas by using IMS, recoveries of 31.5% of cysts and 5.75% of oocysts were reached. When analyzing the coagulant performance, a dosage of 65 mg L(-1) showed contamination from protozoans in all the samples of filtered water. A dosage of 25 mg L(-1) presented protozoans in 50% of the filtered water samples. The results showed an improved performance for the 25 mg L(-1) dosage; therefore, the control of coagulation and adaptation of detection protocols must be evaluated according to the features of raw water and availability of local resources.

  3. Non-contact assessment of COD and turbidity concentrations in water using diffuse reflectance UV-Vis spectroscopy.

    PubMed

    Agustsson, Jon; Akermann, Oliver; Barry, D Andrew; Rossi, Luca

    2014-08-01

    Water contamination is an important environmental concern underlining the need for reliable real-time information on contaminant concentrations in natural waters. Here, a new non-contact UV-Vis spectroscopic approach for monitoring contaminants in water, and especially wastewater, is proposed. Diffuse reflectance UV-Vis spectroscopy was applied to measure simultaneously the chemical oxygen demand (COD) and turbidity (TUR) concentrations in water. The measurements were carried out in the wavelength range from 200-1100 nm. The measured spectra were analysed using partial-least-squares (PLS) regression. The correlation coefficient between the measured and the reference concentrations of COD and TUR in the water samples were R(2) = 0.85 and 0.96, respectively. These results highlight the potential of non-contact UV-Vis spectroscopy for the assessment of water contamination. A system built on the concept would be able to monitor wastewater pollution continuously, without the need for laborious sample collection and subsequent laboratory analysis. Furthermore, since no parts of the system are in contact with the wastewater stream the need for maintenance is minimised.

  4. Mercury fluxes out of glacial and non-glacial streams, as determined by continuous measurements of turbidity and CDOM

    NASA Astrophysics Data System (ADS)

    Vermilyea, A.; Nagorski, S. A.; Lamborg, C. H.; Scott, D.; Hood, E. W.

    2011-12-01

    Glaciers and icefields along the Alaskan coast contribute nearly half of the freshwater discharge to the Gulf of Alaska and can play an important role in near-shore marine ecosystems. In southeastern Alaska, glaciers are rapidly thinning and retreating and are being replaced by temperate forests and wetlands. This ongoing landscape evolution is altering the sensitivity of coastal watersheds to atmospheric Hg inputs. The influence of glacial runoff with high suspended sediment loads on in-stream mercury fluxes and dynamics is poorly understood. In contrast, numerous studies have shown that streams with large contributions from wetlands typically carry high dissolved organic matter (DOM) and filtered methylmercury (FMHg) loads. This study compares and contrasts the mercury concentrations, fluxes, partitioning, and speciation in two coastal watersheds in southeastern Alaska. The two watersheds are separated by only 23 km and are relatively similar in area, however one is heavily glaciated (Lemon Creek) and one is dominated by temperate forest and wetlands (Peterson Creek). Grab samples for unfiltered total mercury (UTHg), particulate total mercury (PTHg), filtered total mercury (FTHg), and FMHg were taken during three, 4-day sampling periods within the glacial melt season (May-Sept) while continuously monitoring in-situ chromophoric dissolved organic matter (CDOM) fluorescence and stream turbidity. While UTHg concentration-discharge relationships were poor (R2=0.38-0.55) in both streams, flux estimates for UTHg were greatly improved using CDOM fluorescence (R2=0.82) for Peterson Creek, and turbidity (R2=0.81) for Lemon Creek. UTHg concentrations were consistently greater in Peterson Creek (factor of 1.7-2.3); however, the watershed area normalized UTHg flux was 3-6 times greater in glacial Lemon Creek than Peterson Creek across all time periods. In Peterson Creek, the majority of the UTHg was in the filtered phase, whereas in Lemon Creek the majority of the mercury

  5. Theory of scattering of electromagnetic waves of the microwave range in a turbid medium

    NASA Astrophysics Data System (ADS)

    Konstantinov, O. V.; Matveentsev, A. V.

    2013-02-01

    The coefficient of extinction of electromagnetic waves of the microwave range due to their scattering from clusters suspended in an amorphous medium and responsible for turbidity is calculated. Turbidity resembles the case when butter clusters transform water into milk. In the case under investigation, the clusters are conductors (metallic or semiconducting). The extinction coefficient is connected in a familiar way with the cross section of light scattering from an individual cluster. A new formula is derived for the light scattering cross section in the case when damping of oscillations of an electron is due only to spontaneous emission of light quanta. In this case, the resonant scattering cross section for light can be very large. It is shown that this can be observed only in a whisker nanocluster. In addition, the phonon energy on a whisker segment must be higher than the photon energy, which is close to the spacing between the electron energy levels in the cluster.

  6. Digital optical phase conjugation for delivering two-dimensional images through turbid media.

    PubMed

    Hillman, Timothy R; Yamauchi, Toyohiko; Choi, Wonshik; Dasari, Ramachandra R; Feld, Michael S; Park, YongKeun; Yaqoob, Zahid

    2013-01-01

    Optical transmission through complex media such as biological tissue is fundamentally limited by multiple light scattering. Precise control of the optical wavefield potentially holds the key to advancing a broad range of light-based techniques and applications for imaging or optical delivery. We present a simple and robust digital optical phase conjugation (DOPC) implementation for suppressing multiple light scattering. Utilizing wavefront shaping via a spatial light modulator (SLM), we demonstrate its turbidity-suppression capability by reconstructing the image of a complex two-dimensional wide-field target through a highly scattering medium. Employing an interferometer with a Sagnac-like ring design, we successfully overcome the challenging alignment and wavefront-matching constraints in DOPC, reflecting the requirement that the forward- and reverse-propagation paths through the turbid medium be identical. By measuring the output response to digital distortion of the SLM write pattern, we validate the sub-wavelength sensitivity of the system.

  7. An improved 96-well turbidity assay for T4 lysozyme activity

    PubMed Central

    Toro, Tasha B.; Nguyen, Thao P.; Watt, Terry J.

    2015-01-01

    T4 lysozyme (T4L) is an important model system for investigating the relationship between protein structure and function. Despite being extensively studied, a reliable, quantitative activity assay for T4L has not been developed. Here, we present an improved T4L turbidity assay as well as an affinity-based T4L expression and purification protocol. This assay is designed for 96-well format and utilizes conditions amenable for both T4L and other lysozymes. This protocol enables easy, efficient, and quantitative characterization of T4L variants and allows comparison between different lysozymes. Our method: • Is applicable for all lysozymes, with enhanced sensitivity for T4 lysozyme compared to other 96-well plate turbidity assays; • Utilizes standardized conditions for comparing T4 lysozyme variants and other lysozymes; and • Incorporates a simplified expression and purification protocol for T4 lysozyme. PMID:26150996

  8. Characterisation of the turbid particles in the extraction of sugar beet pectins.

    PubMed

    Guo, Xiao-Ming; Zhu, Si-Ming; Tang, Qiang; Yu, Shu-Juan

    2014-11-01

    This paper was aimed at characterising the insoluble substances (IS) responsible for the turbidity of the extract and impurity of the resulting pectins. Results showed that the IS caused a significant increase in the turbidity of the extract. The IS had bi-pyramidal shapes under the SEM observation. The observed XRD peaks for the IS were similar to those of calcium oxalate dihydrate (COD). Moreover, the IS consisted of mainly oxalate and calcium. Results from the present study indicate the IS is COD. The influence of the IS on the purity of pectin was also studied. The presence of the IS in the pectins indicated the IS can precipitate with pectins during the alcohol precipitation, thereby contaminating the resulting pectins.

  9. Photon diffusion near the point-of-entry in anisotropically scattering turbid media

    PubMed Central

    Vitkin, Edward; Turzhitsky, Vladimir; Qiu, Le; Guo, Lianyu; Itzkan, Irving; Hanlon, Eugene B.; Perelman, Lev T.

    2012-01-01

    From astronomy to cell biology, the manner in which light propagates in turbid media has been of central importance for many decades. However, light propagation near the point-of-entry (POE) in turbid media has never been analytically described, until now. Here we report a straightforward and accurate method that overcomes this longstanding, unsolved problem in radiative transport. Our theory properly treats anisotropic photon scattering events and takes the specific form of the phase function into account. As a result, our method correctly predicts the spatially dependent diffuse reflectance of light near the POE for any arbitrary phase function. We demonstrate that the theory is in excellent agreement with both experimental results and Monte Carlo simulations for several commonly used phase functions. PMID:22158442

  10. Turbidity currents: monitoring their occurrence and movement with a three-dimensional sensor network.

    PubMed

    Weirich, F H

    1984-04-27

    Detailed field data on the occurrence, flow pattern, and internal dynamics of both surge and continuous turbidity currents have been obtained with a three-dimensional array of optical and thermal sensors. The array, operated in a glacial lake in southeastern British Columbia, collected detailed information on the character of surge events with velocities reaching 110 centimeters per second and continuous underflows exceeding 90 centimeters per second. Thefindings (i) indicate that such currents are frequent events, occurring with density differences between the incoming stream water and the lake water as low as 0.19 kilogram per cubic meter of water; (ii) document the differences in the initiation and internal characteristics of the continuous and surge events; and (iii) support the concept of erosion by turbidity currents.

  11. Reflection-mode time-reversed ultrasonically encoded optical focusing into turbid media.

    PubMed

    Lai, Puxiang; Xu, Xiao; Liu, Honglin; Suzuki, Yuta; Wang, Lihong V

    2011-08-01

    Time-reversed ultrasonically encoded (TRUE) optical focusing was recently proposed to deliver light dynamically to a tight region inside a scattering medium. In this letter, we report the first development of a reflection-mode TRUE optical focusing system. A high numerical aperture light guide is used to transmit the diffusely reflected light from a turbid medium to a phase-conjugate mirror (PCM), which is sensitive only to the ultrasound-tagged light. From the PCM, a phase conjugated wavefront of the tagged light is generated and conveyed by the same light guide back to the turbid medium, subsequently converging to the ultrasonic focal zone. We present experimental results from this system, which has the ability to focus light in a highly scattering medium with a round-trip optical penetration thickness (extinction coefficient multiplied by round-trip depth) as large as 160.

  12. LASERS IN MEDICINE: Determination of the optical characteristics of turbid media by the laser optoacoustic method

    NASA Astrophysics Data System (ADS)

    Karabutov, Aleksander A.; Pelivanov, Ivan M.; Podymova, N. B.; Skipetrov, S. E.

    1999-12-01

    A method, based on the optoacoustic effect for determination of the spatial distribution of the light intensity in turbid media and of the optical characteristics of such media was proposed (and implemented experimentally). A temporal profile of the pressure of a thermo-optically excited acoustic pulse was found to be governed by the absorption coefficient and by the spatial distribution of the light intensity in the investigated medium. The absorption coefficient and the reduced light-scattering coefficient of model turbid water-like media were measured by the optoacoustic method. The results of a direct determination of the spatial light-intensity distribution agreed with a theoretical calculation made in the diffusion approximation.

  13. A highly sensitive underwater video system for use in turbid aquaculture ponds

    NASA Astrophysics Data System (ADS)

    Hung, Chin-Chang; Tsao, Shih-Chieh; Huang, Kuo-Hao; Jang, Jia-Pu; Chang, Hsu-Kuang; Dobbs, Fred C.

    2016-08-01

    The turbid, low-light waters characteristic of aquaculture ponds have made it difficult or impossible for previous video cameras to provide clear imagery of the ponds’ benthic habitat. We developed a highly sensitive, underwater video system (UVS) for this particular application and tested it in shrimp ponds having turbidities typical of those in southern Taiwan. The system’s high-quality video stream and images, together with its camera capacity (up to nine cameras), permit in situ observations of shrimp feeding behavior, shrimp size and internal anatomy, and organic matter residues on pond sediments. The UVS can operate continuously and be focused remotely, a convenience to shrimp farmers. The observations possible with the UVS provide aquaculturists with information critical to provision of feed with minimal waste; determining whether the accumulation of organic-matter residues dictates exchange of pond water; and management decisions concerning shrimp health.

  14. A highly sensitive underwater video system for use in turbid aquaculture ponds

    PubMed Central

    Hung, Chin-Chang; Tsao, Shih-Chieh; Huang, Kuo-Hao; Jang, Jia-Pu; Chang, Hsu-Kuang; Dobbs, Fred C.

    2016-01-01

    The turbid, low-light waters characteristic of aquaculture ponds have made it difficult or impossible for previous video cameras to provide clear imagery of the ponds’ benthic habitat. We developed a highly sensitive, underwater video system (UVS) for this particular application and tested it in shrimp ponds having turbidities typical of those in southern Taiwan. The system’s high-quality video stream and images, together with its camera capacity (up to nine cameras), permit in situ observations of shrimp feeding behavior, shrimp size and internal anatomy, and organic matter residues on pond sediments. The UVS can operate continuously and be focused remotely, a convenience to shrimp farmers. The observations possible with the UVS provide aquaculturists with information critical to provision of feed with minimal waste; determining whether the accumulation of organic-matter residues dictates exchange of pond water; and management decisions concerning shrimp health. PMID:27554201

  15. Determination of turbidity patterns in Lake Chicot from LANDSAT MSS imagery

    NASA Technical Reports Server (NTRS)

    Lecroy, S. R.

    1982-01-01

    A historical analysis of all the applicable LANDSAT imagery was conducted on the turbidity patterns of Lake Chicot, located in the southeastern corner of Arkansas. By examining the seasonal and regional turbidity patterns, a record of sediment dynamics and possible disposition can be obtained. Sketches were generated from the suitable imagery, displaying different intensities of brightness observed in bands 5 and 7 of LANDSAT's multispectral scanner data. Differences in and between bands 5 and 7 indicate variances in the levels of surface sediment concentrations. High sediment loads are revealed when distinct patterns appear in the band 7 imagery. Additionally, the upwelled signal is exponential in nature and saturates in band 5 at low wavelengths for large concentrations of suspended solids.

  16. Measurement and calculation of the two-dimensional backscattering Mueller matrix of a turbid medium.

    PubMed

    Cameron, B D; Rakovic, M J; Mehrübeoglu, M; Kattawar, G W; Rastegar, S; Wang, L V; Coté, G L

    1998-04-01

    We present both experimental and Monte Carlo-based simulation results for the diffusely backscattered intensity patterns that arise from illumination of a turbid medium with a polarized laser beam. A numerical method that allows the calculation of all 16 elements of the two-dimensional Muller matrix is used; moreover, it is shown that only seven matrix elements are independent. To validate our method, we compared our simulations with experimental measurements, using a turbid medium consisting of 2.02-microm -diameter polystyrene spheres suspended in deionized water. By varying the incident polarization and the analyzer optics for the experimental measurements, we obtained the diffuse backscattering Mueller matrix elements. The experimental and the numerical results are in good agreement.

  17. What are the implications of rapid global warming for landslide-triggered turbidity current activity?

    NASA Astrophysics Data System (ADS)

    Clare, Michael; Peter, Talling; James, Hunt

    2014-05-01

    A geologically short-lived (~170kyr) episode of global warming occurred at ~55Ma, termed the Initial Eocene Thermal Maximum (IETM). Global temperatures rose by up to 8oC over only ~10kyr and a massive perturbation of the global carbon cycle occurred; creating a negative carbon isotopic (~-4% δ13C) excursion in sedimentary records. This interval has relevance to study of future climate change and its influence on geohazards including submarine landslides and turbidity currents. We analyse the recurrence frequency of turbidity currents, potentially initiated from large-volume slope failures. The study focuses on two sedimentary intervals that straddle the IETM and we discuss implications for turbidity current triggering. We present the results of statistical analyses (regression, generalised linear model, and proportional hazards model) for extensive turbidite records from an outcrop at Zumaia in NE Spain (N=285; 54.0 to 56.5 Ma) and based on ODP site 1068 on the Iberian Margin (N=1571; 48.2 to 67.6 Ma). The sedimentary sequences provide clear differentiation between hemipelagic and turbiditic mud with only negligible evidence of erosion. We infer dates for turbidites by converting hemipelagic bed thicknesses to time using interval-averaged accumulation rates. Multi-proxy dating techniques provide good age constraint. The background trend for the Zumaia record shows a near-exponential distribution of turbidite recurrence intervals, while the Iberian Margin shows a log-normal response. This is interpreted to be related to regional time-independence (exponential) and the effects of additive processes (log-normal). We discuss how a log-normal response may actually be generated over geological timescales from multiple shorter periods of random turbidite recurrence. The IETM interval shows a dramatic departure from both these background trends, however. This is marked by prolonged hiatuses (0.1 and 0.6 Myr duration) in turbidity current activity in contrast to the

  18. Optical imaging through dynamic turbid media using the Fourier-domain shower-curtain effect.

    PubMed

    Edrei, Eitan; Scarcelli, Giuliano

    2016-01-20

    Several phenomena have been recently exploited to circumvent scattering and have succeeded in imaging or focusing light through turbid layers. However, the requirement for the turbid medium to be steady during the imaging process remains a fundamental limitation of these methods. Here we introduce an optical imaging modality that overcomes this challenge by taking advantage of the so-called shower-curtain effect, adapted to the spatial-frequency domain via speckle correlography. We present high resolution imaging of objects hidden behind millimeter-thick tissue or dense lens cataracts. We demonstrate our imaging technique to be insensitive to rapid medium movements (> 5 m/s) beyond any biologically-relevant motion. Furthermore, we show this method can be extended to several contrast mechanisms and imaging configurations.

  19. Optical imaging through dynamic turbid media using the Fourier-domain shower-curtain effect

    PubMed Central

    Edrei, Eitan; Scarcelli, Giuliano

    2016-01-01

    Several phenomena have been recently exploited to circumvent scattering and have succeeded in imaging or focusing light through turbid layers. However, the requirement for the turbid medium to be steady during the imaging process remains a fundamental limitation of these methods. Here we introduce an optical imaging modality that overcomes this challenge by taking advantage of the so-called shower-curtain effect, adapted to the spatial-frequency domain via speckle correlography. We present high resolution imaging of objects hidden behind millimeter-thick tissue or dense lens cataracts. We demonstrate our imaging technique to be insensitive to rapid medium movements (> 5 m/s) beyond any biologically-relevant motion. Furthermore, we show this method can be extended to several contrast mechanisms and imaging configurations. PMID:27347498

  20. Measuring turbidity, and indicator to evaluate drinkability of waters in Southern countries? Approaches from Burkina Faso, Sudan and Argentina case studies

    NASA Astrophysics Data System (ADS)

    Lavie, Emilie; Robert, Elodie

    2013-04-01

    and its tributaries were not transformed upstream our sample points (Lavie et al., 2013, under press). Finally, we studied an urban drinking waters network, in Khartoum, the capital of Sudan, one of the least developed countries, with chronic political crises. The nearly 6 million inhabitants of this settlement suffer many cuts and bad pressure at tap. Furthermore, Nile's waters that feed the network are summarily treated and then quite turbid, especially in summer during Nile's floods. This situation obliges the population to store and to decant water, transforming it into clear ones (Lavie and Hamza, 2013, under press). The results of our studies demonstrate that, generally, we can observe a correlation between increasing turbidity and bacteriology, and decreasing oximetry. This assumption is disproven in many cases: (1) the stagnant waters of Khartoum and (2) the clarified Mendoza River waters. Finally, (3) the seasonal anthropogenic uses of soil and waters in the Doubegue and Tunuyán Rivers have more impact on the bacteriological quality than the natural seasonality of the suspended solids because soil erosion has increased.

  1. Evaluating external nutrient and suspended-sediment loads to Upper Klamath Lake, Oregon, using surrogate regressions with real-time turbidity and acoustic backscatter data

    USGS Publications Warehouse

    Schenk, Liam N.; Anderson, Chauncey W.; Diaz, Paul; Stewart, Marc A.

    2016-12-22

    the two study sites, particularly in using turbidity to compute suspended-sediment concentrations in the Williamson River. This proof-of-concept effort for computing total phosphorus concentrations using turbidity at the Williamson and Wood River sites also has shown that with additional samples over a wide range of flow regimes, high-temporal-resolution total phosphorus loads can be estimated on a daily, monthly, and annual basis, along with uncertainties for total phosphorus and suspended-sediment concentrations computed using regression models. Sediment-corrected backscatter at the Wood River has potential for estimating suspended-sediment loads from the Wood River Valley as well, with additional analysis of the variable streamflow measured at that site. Suspended-sediment and total phosphorus loads with a high level of temporal resolution will be useful to water managers, restoration practitioners, and scientists in the Upper Klamath Basin working toward the common goal of decreasing nutrient and sediment loads in Upper Klamath Lake.

  2. The Response of Suspended Sediment, Turbidity, and Velocity to Historical Alterations of the Missouri River

    USGS Publications Warehouse

    Blevins, Dale W.

    2006-01-01

    The heavy sediment load and large amounts of floating debris generated by the constantly caving banks of the Missouri River was documented in the first written description of the river by Father Jacques Marquette in 1673 as he approached the mouth of the Missouri River from the upper Mississippi River: '[We]' heard the noise of a rapid, into which we were about to run. I have seen nothing more dreadful. An accumulation of large and entire trees, branches, and floating islands, was issuing from the mouth of the river Pekitanoui (Missouri River), with such impetuosity that we could not without great danger risk passing through it. So great was its agitation that the water was so very muddy, and could not become clear.' However, large changes in suspended sediment and turbidity in the lower Missouri River below Gavins Point Dam have occurred in response to extensive structural changes that have been imposed on the Missouri River and its watershed during the last two centuries. Efforts to shape the channel, remove snags and sawyers, dredge shallows, and stabilize banks for navigation began as early as 1838 ( http://www.lewis-clark.org/ri_mo-snagboats.htm , Chittenden, 1903). However, bank stabilization efforts were sporadic and scattered in comparison to large scale changes that occurred after 1929. In the early 1930s the numerous small channels were combined into a single-fixed channel with 4,745 stone and wood-pile dikes, 3,371 dike extensions, streambank protection works on concave banks, man-made cutoffs, the closing of chutes with dikes, the removal of snags, and dredging (Keown and others, 1981). The resulting navigation channel was 6-ft (feet) deep by 200-ft wide and was expanded to 9 by 300 ft in the 1950s and early 1960s. Construction of six dams was started in 1933 and their reservoirs were filled by 1967. Three of these reservoirs are among the five largest in the United States. Nearly one-third of the Missouri River is now submerged below these massive

  3. Are flood-driven turbidity currents hot spots for priming effect in lakes?

    NASA Astrophysics Data System (ADS)

    Bouffard, Damien; Perga, Marie-Elodie

    2016-06-01

    In deep stratified lakes, such as Lake Geneva, flood-driven turbidity currents are thought to contribute to the replenishment of deep oxygen by significant transport of river waters saturated with oxygen into the hypolimnion. The overarching aim of this study was to test this long-standing hypothesis directly. It combines direct observational data collected during an extreme flooding event that occurred in May 2015 with dark bioassays designed to evaluate the consequences of river-borne inputs for the hypolimnetic respiration. The exceptional precipitation events of May 2015 caused floods with an annual return time for the Rhône River, the dominant tributary of Lake Geneva, and with 50-year return time for the Dranse River, the second-most important tributary. Sediment-loaded river flows generated turbidity currents plunging into the lake hypolimnion. The observed river intrusions contributed to the redistribution of dissolved oxygen, with no net gain, when occurring in the lowermost hypolimnetic layer. In the uppermost hypolimnion above the last deep-mixing event, the intrusions coincided with a net oxygen deficit. Consistent with field observations, dark bioassays showed that 1 to 50 % substitution of riverine organic matter to deep (< 200 m) hypolimnetic water did not affect microbial respiration, while the addition of 1 to 10 % of riverine water to the uppermost hypolimnetic waters resulted in a respiration over-yielding, i.e. excess respiration of both river-borne and lacustrine organic matter. The results of our study conflict with the hypothesis that flood-driven turbidity currents necessarily increase hypolimnetic oxygen stocks in Lake Geneva. In contrast, results show that flood-driven turbidity currents can be potential hot spots for priming effect in lakes.

  4. Temporal variability of atmospheric turbidity and DNI attenuation in the sugarcane region, Botucatu/SP

    NASA Astrophysics Data System (ADS)

    Santos, Cícero Manoel dos; Escobedo, João Francisco

    2016-11-01

    In this study, attenuation of direct normal solar irradiance (DNI) in Botucatu / São Paulo, an area under the influence of local and adjacent agricultural burning, is expressed using the Linke's turbidity factor (TL) in the period from 1996 to 2008. Two methodologies represented as TLDj and TLLi were used. Temporal variability (hourly average for the season and monthly average) is presented. Turbidity was correlated with wind speed and air temperature. Frequency distribution and cumulative frequency are analyzed to determine turbidity predominance levels in the local atmosphere. Optical depth information of aerosols at 550 nm (AOD550nm) and water vapor were obtained by the Terra satellite using the MODIS sensor. The highest degree of DNI transmission is observed in the morning. Close to solar noon, transmission is smaller (greatest TL value). Diurnal TL variability is more evident in the hot period than in the cold period. May and June were the months of lowest DNI attenuation (highest atmospheric transparency). The highest DNI attenuation occurs in spring (TLDj = 4.22 ± 0.05 and TLLi = 4.65 ± 0.06) and summer (TLDj = 4.27 ± 0.14 and TLLi = 4.69 ± 0.15). Wind speed and air temperature were positively correlated with TL. In > 28% of hours of clear sky, turbidity exceeded the value of 4.0. The region of Botucatu seems to be influenced by water vapor and aerosols from different origins. This study concludes that these factors significantly reduce DNI incidence on the surface, with higher atmospheric transparency in the cold period and lower atmospheric transparency in the warm period.

  5. Observations of the Columbia River salt wedge and estuarine turbidity maximum using AUVs

    NASA Astrophysics Data System (ADS)

    McNeil, C. L.; Shcherbina, A.; Litchendorf, T.; Sanford, T. B.; Martin, D.; Baptista, A. M.; Lopez, J.; Crump, B.

    2012-12-01

    We present detailed observations of the salt wedge and estuarine turbidity maxima (ETM) in the North Channel of the Columbia River estuary (OR, USA) under conditions of high river discharge during May 2012. Measurements were made using two REMUS-100 autonomous underwater vehicles (AUVs; Hydroid, Inc.) equipped with SBE-49 CTDs (Seabird-Electronics, Inc.) for water temperature and salinity, upward/downward looking ADCPs (Teledyne RDI, Inc.) for currents, and ECO Puck triplets (WET Labs, Inc.) for optical backscatter measurement of turbidity. The acoustic backscatter intensity from the ADCP was also used as a proxy measurement for suspended sediments and was found to correlate quite well with the optical backscatter measurements. Daily forecasts of tidal currents in the estuary were used to simulate the AUV path in advance of deployment to aid data collection. Repeat AUV sections were made along and across the channel during flood tide. The turbidity and height above riverbed of the bottom boundary layer was observed to increase toward the deeper waters at the center of the channel. An ETM-like feature was observed ahead of the advancing salt wedge front with locally higher turbidity levels, presumably the result of flocculation and resuspension. To visualize better the repeat section measurements we made data movies. Each frame of the movie is our best estimate of a synoptic snapshot of along-section tracer distribution at a given point in time. These snapshots were created by re-location of non-synoptic AUV measurements to account for the advection of water parcels. An example data movie showing the intrusion of the salt wedge during the flood tide will be presented.

  6. In situ tryptophan-like fluorometers: assessing turbidity and temperature effects for freshwater applications.

    PubMed

    Khamis, K; Sorensen, J P R; Bradley, C; Hannah, D M; Lapworth, D J; Stevens, R

    2015-04-01

    Tryptophan-like fluorescence (TLF) is an indicator of human influence on water quality as TLF peaks are associated with the input of labile organic carbon (e.g. sewage or farm waste) and its microbial breakdown. Hence, real-time measurement of TLF could be particularly useful for monitoring water quality at a higher temporal resolution than available hitherto. However, current understanding of TLF quenching/interference is limited for field deployable sensors. We present results from a rigorous test of two commercially available submersible tryptophan fluorometers (ex ∼ 285, em ∼ 350). Temperature quenching and turbidity interference were quantified in the laboratory and compensation algorithms developed. Field trials were then undertaken involving: (i) an extended deployment (28 days) in a small urban stream; and, (ii) depth profiling of an urban multi-level borehole. TLF was inversely related to water temperature (regression slope range: -1.57 to -2.50). Sediment particle size was identified as an important control on the turbidity specific TLF response, with signal amplification apparent <150 NTU for clay particles and <650 NTU for silt particles. Signal attenuation was only observed >200 NTU for clay particles. Compensation algorithms significantly improved agreement between in situ and laboratory readings for baseflow and storm conditions in the stream. For the groundwater trial, there was an excellent agreement between laboratory and raw in situ TLF; temperature compensation provided only a marginal improvement, and turbidity corrections were unnecessary. These findings highlight the potential utility of real time TLF monitoring for a range of environmental applications (e.g. tracing polluting sources and monitoring groundwater contamination). However, in situations where high/variable suspended sediment loads or rapid changes in temperature are anticipated concurrent monitoring of turbidity and temperature is required and site specific calibration is

  7. Laser photothermoacoustic heterodyned lock-in depth profilometry in turbid tissue phantoms.

    PubMed

    Fan, Ying; Mandelis, Andreas; Spirou, Gloria; Vitkin, I Alex; Whelan, William M

    2005-11-01

    Frequency-domain correlation and spectral analysis photothermoacoustic (FD-PTA) imaging is a promising new technique, which is being developed to detect tumor masses in turbid biological tissue. Unlike conventional biomedical photoacoustics which uses time-of-flight acoustic information induced by a pulsed laser to indicate the tumor size and location, in this research, a new FD-PTA instrument featuring frequency sweep (chirp) and heterodyne modulation and lock-in detection of a continuous-wave laser source at wavelength is constructed and tested for its depth profilometric capabilities with regard to turbid media imaging. Owing to the linear relationship between the depth of acoustic signal generation and the delay time of signal arrival to the transducer, information specific to a particular depth can be associated with a particular frequency in the chirp signal. Scanning laser-fluence modulation frequencies with a linear frequency sweep method preserves the depth-to-delay time linearity and recovers FD-PTA signals from a range of depths. Combining with the depth information carried by the back-propagated acoustic chirp signal at each scanning position, one could rapidly generate subsurface three-dimensional images of the scanning area at optimal signal-to-noise ratios and low laser fluences, a combination of tasks that is difficult or impossible by use of pulsed photoacoustic detection. In this paper, results of PTA scans performed on tissue mimicking control phantoms with various optical, acoustical, and geometrical properties are presented. A mathematical model is developed to study the laser-induced photothermoacoustic waves in turbid media. The model includes both the scattering and absorption properties of the turbid medium. A good agreement is obtained between the experimental and numerical results. It is concluded that frequency domain photothermoacoustics using a linear frequency sweep method and heterodyne lock-in detection has the potential to be a

  8. Processes that initiate turbidity currents and their influence on turbidites: A marine geology perspective

    USGS Publications Warehouse

    Piper, David J.W.; Normark, William R.

    2009-01-01

    How the processes that initiate turbidity currents influence turbidite deposition is poorly understood, and many discussions in the literature rely on concepts that are overly simplistic. Marine geological studies provide information on the initiation and flow path of turbidity currents, including their response to gradient. In case studies of late Quaternary turbidites on the eastern Canadian and western U.S. margins, initiation processes are inferred either from real-time data for historical flows or indirectly from the age and contemporary paleogeography, erosional features, and depositional record. Three major types of initiation process are recognized: transformation of failed sediment, hyperpycnal flow from rivers or ice margins, and resuspension of sediment near the shelf edge by oceanographic processes. Many high-concentration flows result from hyperpycnal supply of hyperconcentrated bedload, or liquefaction failure of coarse-grained sediment, and most tend to deposit in slope conduits and on gradients < 0.5?? at the base of slope and on the mid fan. Highly turbulent flows, from transformation of retrogressive failures and from ignitive flows that are triggered by oceanographic processes, tend to cannibalize these more proximal sediments and redeposit them on lower gradients on the basin plain. Such conduit flushing provides most of the sediment in large turbidites. Initiation mechanism exerts a strong control on the duration of turbidity flows. In most basins, there is a complex feedback between different types of turbidity-current initiation, the transformation of the flows, and the associated slope morphology. As a result, there is no simple relationship between initiating process and type of deposit. ?? 2009, SEPM (Society for Sedimentary Geology).

  9. Turbidity in extreme western Lake Superior. [contamination of Duluth, Minnesota water intake

    NASA Technical Reports Server (NTRS)

    Sydor, M.

    1975-01-01

    Data were obtained from ERTS images for western Lake Superior for 1972-74. Data examination showed that for easterly winds the turbidity originating along the Wisconsin shore and the resuspension areas are transported northward then out along a N.E. path where it disperses, and often, for large storms, contaminates the Duluth water intake. Contaminants such as dredging fines anywhere along these paths would likewise find their way to the intake areas in concentrations comparable to the relative red clay concentration.

  10. Relevance of different spectral techniques to describe estuarine suspended sediment dynamics based on a high-frequency, long-term turbidity dataset

    NASA Astrophysics Data System (ADS)

    Jalón Rojas, Isabel; Schmidt, Sabine; Sottolichio, Aldo

    2015-04-01

    Sediment dynamics in estuaries are complex and strongly variable over time scales ranging from seconds to years. Various forcings (turbulence, tides, river inflow, wind waves, morphological and climatic changes) may cause the temporal and spatial variability of suspended sediment (SS) concentrations. The evaluation of these SS dynamics by in-situ measurements have traditionally faced three difficulties: (1) the quantification of low-frequency variability that requires continuous measures over long time periods; (2) inevitable gaps in data limiting the post-processing; (3) the need for recording other environmental variables in the same period and at a coherent sampling frequency. To record a high-frequency and long-term turbidity dataset, an automatic monitoring network (MAGEST) has been implemented in the Gironde estuary, a macrotidal and highly turbid system in the South-West France, in 2004. This 10-year turbidity time series is rather unique in European estuaries, enabling the evaluation of SS dynamics at all the significant time scales in one single analysis of the dataset. To achieve this, several methodologies of data analysis using different approaches are available, but their relevance, especially for the more recently developed ones, is almost unexplored. In this work, we present the test of four spectral techniques to the analysis of a high-frequency turbidity time series of an estuary such as the Gironde, to discuss advantages and limitations of each method. We compare the Power Spectral Analysis (PSA), the Singular Spectral Analysis (SSA), the Wavelet Transform (WT) and the Empirical Mode Decomposition (EMD). Advantages and limitations of each method are evaluated on the basis of five criteria: efficiency for incomplete time series, appropriateness for time-varying analysis, ability to recognize processes without the need of complementary environmental variables, capacity to calculate the relative importance of processes, and capacity to identify long

  11. Speckle-correlation imaging through highly scattering turbid media with LED illumination

    NASA Astrophysics Data System (ADS)

    Shao, Xiaopeng; Dai, Weijia; Wu, Tengfei; Li, Huijuan; Wang, Lin

    2015-05-01

    We address an optical imaging method that allows imaging, which owing to the "memory-effect" for speckle correlations, through highly scattering turbid media with "Error Reduction - Hybid Input Ouput (ER-HIO)" algorithm. When light propagates through the opaque materials, such as white paint, paper or biological tissues, it will be scattered away due to the inhomogeneity of the refractive index. Multiple scattering of light in highly scattering media forms speckle field, which will greatly reduce the imaging depth and degrade the imaging quality. Some methods have been developed to solve this problem in recent years, including wavefront modulation method (WMM), transmission matrix method (TMM) and speckle correlations method (SCM). A novel approach is proposed to image through a highly scattering turbid medium, which combines speckle correlations method (SCM) with phase retrieval algorithm (PRA). Here, we show that, owing to the "optical memory effect" for speckle correlations, a single frame image of the speckle field, captured with a high performance detector, encodes sufficient information to image through highly scattering turbid media. Theoretical and experimental results show that, neither the light source, nor wave-front shaping is required in this method, and that the imaging can be easily realized here using just a simple optical system with the help of optical memory effect. Our method does not require coherent light source, which can be achieved with LED illumination, unlike previous approaches, and therefore is potentially suitable for more and more areas. Consequently, it will be beneficial to achieve imaging in currently inaccessible scenarios.

  12. Turbidity characterizes the reproduction areas of pikeperch ( Sander lucioperca (L.)) in the northern Baltic Sea

    NASA Astrophysics Data System (ADS)

    Veneranta, L.; Urho, L.; Lappalainen, A.; Kallasvuo, M.

    2011-11-01

    The pikeperch ( Sander lucioperca (L.)) is an economically important fish species occurring in the fresh and brackish waters of Europe. To evaluate the distribution and extent of the reproduction areas in the northern Baltic Sea, a field survey was carried out in two separate coastal areas. Presence/absence data were used to develop a geographic information system (GIS)-based predictive spatial distribution model, where high resolution raster maps of the focal environmental variables and a logistic regression equation were used to predict the probability of larval occurrence. The results indicated that the pikeperch reproduction areas are located in the innermost archipelago zone where high water turbidity best explained their presence. Turbidity was related to several other variables such as fetch and depth. Contrary to our preliminary hypothesis, surface water temperatures measured during the survey had no significant effect in the model due to the low spatial variation in the measured values. Since turbidity is possible to determine by remote sensing methods, the probability maps can be cost-effectively extended to more extensive coastal areas with proper validation.

  13. Effects of turbidity, light level, and cover on predation of white sturgeon larvae by prickly sculpins

    USGS Publications Warehouse

    Gadomski, D.M.; Parsley, M.J.

    2005-01-01

    White sturgeon Acipenser transmontanus occur in rivers of the western United States and southwestern Canada, but some populations are in decline because of recruitment failure. Many river systems in this area have been altered as a result of development that has caused major environmental changes. Our goal was to examine how three changes - lower turbidity levels, higher light levels, and altered substrates - might affect predation by prickly sculpin Cottus asper on white sturgeon larvae. We experimentally investigated predation at various turbidity levels and found that significantly more white sturgeon yolk sac larvae were eaten at lower turbidity levels. The effects of light level (1-4 and 7-15 1x), the presence or absence of rocks as cover, and prey size (14-17 mm and 20-24 mm total length) on the outcome of predator-prey interactions were also examined. Significantly fewer white sturgeon were eaten during trials that combined the lowest light level, cover, and the smallest larvae. Our results suggest that altered river conditions caused by impoundment and other factors have increased predation on white sturgeon larvae. ?? Copyright by the American Fisheries Society 2005.

  14. Multiphoton fluorescence microscopic imaging through double-layer turbid tissue media

    NASA Astrophysics Data System (ADS)

    Deng, Xiaoyuan; Gan, Xiaosong; Gu, Min

    2002-04-01

    Image formation in multiphoton fluorescence microscopy through double-layer turbid tissue media is investigated using Monte Carlo simulation. With the help of the concept of the effective point spread function, the relationship of image resolution and signal level to the thickness and scattering properties of the double-layer turbid media under single-, two-, and three-photon excitation is revealed. Results show that for a double-layer turbid medium of a given thickness, small particles in the top layer result in a quicker degradation of signal level than large particles in the top layer. This model is then applied to study the penetration depth of multiphoton fluorescence microscopy through human skin tissue which exhibits a layered structure. It is predicated that using 3p excitation leads to a signal level up to two orders of magnitude higher than that under 2p excitation, while diffraction-limited image resolution can be maintained for skin tissue of thickness up to 500 μm.

  15. Hybrid diffusion-P3 equation in N-layered turbid media: steady-state domain.

    PubMed

    Shi, Zhenzhi; Zhao, Huijuan; Xu, Kexin

    2011-10-01

    This paper discusses light propagation in N-layered turbid media. The hybrid diffusion-P3 equation is solved for an N-layered finite or infinite turbid medium in the steady-state domain for one point source using the extrapolated boundary condition. The Fourier transform formalism is applied to derive the analytical solutions of the fluence rate in Fourier space. Two inverse Fourier transform methods are developed to calculate the fluence rate in real space. In addition, the solutions of the hybrid diffusion-P3 equation are compared to the solutions of the diffusion equation and the Monte Carlo simulation. For the case of small absorption coefficients, the solutions of the N-layered diffusion equation and hybrid diffusion-P3 equation are almost equivalent and are in agreement with the Monte Carlo simulation. For the case of large absorption coefficients, the model of the hybrid diffusion-P3 equation is more precise than that of the diffusion equation. In conclusion, the model of the hybrid diffusion-P3 equation can replace the diffusion equation for modeling light propagation in the N-layered turbid media for a wide range of absorption coefficients.

  16. Analytical solution of the simplified spherical harmonics equations in spherical turbid media

    NASA Astrophysics Data System (ADS)

    Edjlali, Ehsan; Bérubé-Lauzière, Yves

    2016-10-01

    We present for the first time an analytical solution for the simplified spherical harmonics equations (so-called SPN equations) in the case of a steady-state isotropic point source inside a spherical homogeneous absorbing and scattering medium. The SPN equations provide a reliable approximation to the radiative transfer equation for describing light transport inside turbid media. The SPN equations consist of a set of coupled partial differential equations and the eigen method is used to obtain a set of decoupled equations, each resembling the heat equation in the Laplace domain. The equations are solved for the realistic partial reflection boundary conditions accounting for the difference in refractive indices between the turbid medium and its environment (air) as occurs in practical cases of interest in biomedical optics. Specifically, we provide the complete solution methodology for the SP3, which is readily applicable to higher orders as well, and also give results for the SP5. This computationally easy to obtain solution is investigated for different optical properties of the turbid medium. For validation, the solution is also compared to the analytical solution of the diffusion equation and to gold standard Monte Carlo simulation results. The SP3 and SP5 analytical solutions prove to be in good agreement with the Monte Carlo results. This work provides an additional tool for validating numerical solutions of the SPN equations for curved geometries.

  17. Use of OLCI and SLSTR Bands for Atmospheric Correction over Turbid Coastal and Inland Waters

    NASA Astrophysics Data System (ADS)

    Ruddick, Kevin; Vanhellement, Quinten

    2015-12-01

    The OLCI sensor has strong heritage from MERIS and some new bands, e.g. 400nm and 1020nm. The SLSTR spectral bands at 1.61μm and 2.25μm may also help improve the OLCI atmospheric correction. At 1020nm the water-leaving radiance is much lower than at shorter wavelengths and the spectral shapes of water and aerosol reflectance over the range 709-1020nm will be quite different, even in the most turbid waters. This band may therefore help improve the aerosol correction in extremely turbid waters. At 1.61μm and 2.25μm water-leaving radiance is negligible even for the most turbid waters. The advantage of these bands for atmospheric correction has been demonstrated previously for MODIS and Landsat-8. Exploiting these new bands will involve many challenges including: low signal:noise for the SWIR bands, SWIR contamination by objects at sea, straylight, calibration, OLCI/SLSTR colocation, etc.

  18. Extraction of optical rotation from chiral turbid medium with Mueller matrix decomposition

    NASA Astrophysics Data System (ADS)

    Ma, Yongchao; Sun, Ping; Liu, Wei; Yang, Qinghua; Jia, Qiongzhen

    2013-09-01

    Optical activity is the intrinsic property of chiral molecules. Investigation of optical activity is particularly important for diagnosing and monitoring blood glucose of diabetes. The experimental setup to obtain the Mueller matrix in the forward detection geometry is used. Three kinds of chiral turbid media are selected to be studied in the experiment. The first is the tissue phantom composed of an aqueous solution of glucose mixed with PST sphere suspensions. The second is the actual chicken blood mixed with glucose solution. The last is the vein blood plasma of diabetic patients. The results presented in this study demonstrate that the method of Mueller matrix decomposition can be used to quantitatively extract the optical rotation of chiral molecule in turbid medium. The rotation angle has linear relationship with the concentration of the optical activity material when the scattering coefficient of the turbid medium maintains unchanged. The scattering effect enlarges the rotation angle. Furthermore, optical rotation abides by the Drude's dispersion equation. The decomposition method also has been found useful applications in quantifying the optical rotations due to blood glucose in diabetic patients. The diabetic severity status can be distinguished with the rotation angle of glucose by using the decomposition method and also are in accordance with the clinical diagnosis. Thus, the method of Mueller matrix decomposition has promising applications in diabetic diagnosis.

  19. Variability of Yellow River turbid plume detected with satellite remote sensing during water-sediment regulation

    NASA Astrophysics Data System (ADS)

    Guo, Kai; Zou, Tao; Jiang, Dejuan; Tang, Cheng; Zhang, Hua

    2017-03-01

    Water Sediment Regulations (WSRs) of the Yellow River (YR) have fundamentally altered the dynamics of freshwater and sediment transport in YR estuary and might profoundly affect water quality and ecosystem of the adjacent Bohai Sea. In this study, empirical algorithms were established to infer sea surface salinity and turbidity of YR plume using on surface reflectance products of MODIS and GOCI satellites in combination with observations from hydrographic surveys during the 2014 WSR event. Inter- and intraday variability of salinity and turbidity were quantitatively assessed and correlated with external forces including river discharge, tides, Coriolis force, and wind-driven circulation. The results revealed the enhanced offshore extension of turbid plume as WSR drastically increased freshwater and sediment discharge to river mouth. During WSR event, the area of low salinity plume (<25 psu) increased to 267 km2, while sediment plume (SR645 >0.12sr-1) occupied a maximum area of 162 km2. Intraday variation observed from geostationary GOCI data clearly illustrated the dominance of tidal current on short term dispersal pattern of freshwater and sediment plume. In comparison, wind field dominated the seasonal variation in flume transport but had insignificant impact on short term river plume dynamic during WSR. Overall, this study demonstrated that the spatial and temporal dynamic of YR plume was successfully captured by satellite remote sensing, which provided an effective tool for evaluating the environmental and ecological impact of WSRs.

  20. [Biological flocculants used for turbidity elimination during coagulation in water treatment].

    PubMed

    Zheng, Li-na; Ma, Fang; Chi, Yi

    2008-06-01

    Research was investigated about bioflocculants (BFs) used for turbidity removal from kaolin clay solution and raw water based on jar tests. The results show that the elimination efficiency to turbidity from kaolin clay solution by BFs is 84%, over 5-19 mg/L, which is lower than 93% for Al2(SO4)3 and 94% for Fe2(SO4)3. From the variation of Zeta potential and pH, it was demonstrated that coagulation with BFs was governed by bridging flocculation. It was also observed that the addition of a small amount of inorganic salts (Fe or Al) could substantially enhance the coagulation efficiency. It appeared likely that the combined applications of inorganic salts and BFs resulted in an enhancement of charge neutralization and bridging flocculation. The case study shows that the combination of Fe and BFs can effectively eliminate turbidity from raw water at low dosage and neutral pH (by 94.6%). For biodegradable nature of produced sludge and reducing the health risk related to aluminum accumulation, BFs are considered to be a new type of environmental-friendly flocculants.

  1. Excitation-and-collection geometry insensitive fluorescence imaging of tissue-simulating turbid media.

    PubMed

    Qu, J Y; Huang, Z; Hua, J

    2000-07-01

    We present an imaging technique for the correction of geometrical effects in fluorescence measurement of optically thick, turbid media such as human tissue. Specifically, we use the cross-polarization method to reject specular reflection and enhance the diffusive backscattering of polarized fluorescence excitation light from the turbid media. We correct the nonuniformity of the image field caused by the excitation-and-collection geometry of a fluorescence imaging system by normalizing the fluorescence image to the cross-polarized reflection image. The ratio image provides a map of relative fluorescence yield, defined as the ratio of emerging fluorescence power to incident excitation, over the surface of an imaged homogeneous turbid medium when fluorescence excitation-and-collection geometries vary in a wide range. We investigate the mechanism of ratio imaging by using Monte Carlo modeling. Our findings show that this technique could have a potential use in the detection of early cancer, which usually starts from a superficial layer of tissue, based on the contrast in the tissue fluorescence of an early lesion and of the surrounding normal tissue.

  2. Active imaging with the aids of polarization retrieve in turbid media system

    NASA Astrophysics Data System (ADS)

    Tao, Qiangqiang; Sun, Yongxuan; Shen, Fei; Xu, Qiang; Gao, Jun; Guo, Zhongyi

    2016-01-01

    We propose a novel active imaging based on the polarization retrieve (PR) method in turbid media system. In our simulations, the Monte Carlo (MC) algorithm has been used to investigate the scattering process between the incident photons and the scattering particles, and the visually concordant object but with different polarization characteristics in different regions, has been selected as the original target that is placed in the turbid media. Under linearly and circularly polarized illuminations, the simulation results demonstrate that the corresponding polarization properties can provide additional information for the imaging, and the contrast of the polarization image can also be enhanced greatly compared to the simplex intensity image in the turbid media. Besides, the polarization image adjusted by the PR method can further enhance the visibility and contrast. In addition, by PR imaging method, with the increasing particles' size in Mie's scale, the visibility can be enhanced, because of the increased forward scattering effect. In general, in the same circumstance, the circular polarization images can offer a better contrast and visibility than that of linear ones. The results indicate that the PR imaging method is more applicable to the scattering media system with relatively larger particles such as aerosols, heavy fog, cumulus, and seawater, as well as to biological tissues and blood media.

  3. Effect of storage of shelled Moringa oleifera seeds from reaping time on turbidity removal.

    PubMed

    Golestanbagh, M; Ahamad, I S; Idris, A; Yunus, R

    2011-09-01

    Moringa oleifera is an indigenous plant to Malaysia whose seeds are used for water purification. Many studies on Moringa oleifera have shown that it is highly effective as a natural coagulant for turbidity removal. In this study, two different methods for extraction of Moringa's active ingredient were investigated. Results of sodium chloride (NaCl) and distilled water extraction of Moringa oleifera seeds showed that salt solution extraction was more efficient than distilled water in extracting Moringa's active coagulant ingredient. The optimum dosage of shelled Moringa oleifera seeds extracted by the NaCl solution was comparable with that of the conventional chemical coagulant alum. Moreover, the turbidity removal efficiency was investigated for shelled Moringa oleifera seeds before drying in the oven under different storage conditions (i.e. open and closed containers at room temperature, 27 °C) and durations (fresh, and storage for 2, 4, 6 and 8 weeks from the time the seeds were picked from the trees). Our results indicate that there are no significant differences in coagulation efficiencies and, accordingly, turbidity removals between the examined storage conditions and periods.

  4. Flocculation kinetics of low-turbidity raw water and the irreversible floc breakup process.

    PubMed

    Marques, Rodrigo de Oliveira; Ferreira Filho, Sidney Seckler

    2017-04-01

    The main objective of this study was to propose an improvement to the flocculation kinetics model presented by Argaman and Kaufman, by including a new term that accounts for the irreversible floc breakup process. Both models were fitted to the experimental results obtained with flocculation kinetics assays of low turbidity raw water containing Microcystis aeruginosa cells. Aluminum sulfate and ferric chloride were used as coagulants, and three distinct average velocity gradient (G) values were applied in the flocculation stage (20, 40 and 60 s(-1)). Experimental results suggest that the equilibrium between the aggregation and breakup process, as depicted by Argaman and Kaufman's original model, might not be constant over time, since the residual turbidity increased in various assays (phenomenon that was attributed to the irreversible floc breakup process). In the aluminum sulfate assays, the residual turbidity increase was visible when G = 20 s(-1) (dosages of 60 and 80 mg L(-1)). For the ferric chloride assays, the phenomenon was noticed when G = 60 s(-1) (dosages of 60 and 80 mg L(-1)). The proposed model presented a better fit to the experimental results, especially at higher coagulant dosages and/or higher values of average velocity gradient (G).

  5. Focusing through a turbid medium by amplitude modulation with genetic algorithm

    NASA Astrophysics Data System (ADS)

    Dai, Weijia; Peng, Ligen; Shao, Xiaopeng

    2014-05-01

    Multiple scattering of light in opaque materials such as white paint and human tissue forms a volume speckle field, will greatly reduce the imaging depth and degrade the imaging quality. A novel approach is proposed to focus light through a turbid medium using amplitude modulation with genetic algorithm (GA) from speckle patterns. Compared with phase modulation method, amplitude modulation approach, in which the each element of spatial light modulator (SLM) is either zero or one, is much easier to achieve. Theoretical and experimental results show that, the advantage of GA is more suitable for low the signal to noise ratio (SNR) environments in comparison to the existing amplitude control algorithms such as binary amplitude modulation. The circular Gaussian distribution model and Rayleigh Sommerfeld diffraction theory are employed in our simulations to describe the turbid medium and light propagation between optical devices, respectively. It is demonstrated that the GA technique can achieve a higher overall enhancement, and converge much faster than others, and outperform all algorithms at high noise. Focusing through a turbid medium has potential in the observation of cells and protein molecules in biological tissues and other structures in micro/nano scale.

  6. Suspended sediment concentration and optical property observations of mixed-turbidity, coastal waters through multispectral ocean color inversion

    EPA Science Inventory

    Multispectral satellite ocean color data from high-turbidity areas of the coastal ocean contain information about the surface concentrations and optical properties of suspended sediments and colored dissolved organic matter (CDOM). Empirical and semi-analytical inversion algorit...

  7. 40 CFR 141.550 - Is my system required to meet subpart T combined filter effluent turbidity limits?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... utilize filtration other than slow sand filtration or diatomaceous earth filtration must meet the combined... diatomaceous earth filtration you are not required to meet the combined filter effluent turbidity limits...

  8. In situ sensing to understand diel turbidity cycles, suspended solids, and nutrient transport in Clear Creek, Iowa

    NASA Astrophysics Data System (ADS)

    Loperfido, J. V.; Just, Craig L.; Papanicolaou, Athanasios N.; Schnoor, Jerald L.

    2010-06-01

    Recent advances in sensor technology have made high-frequency environmental data readily available. In this study, high-frequency monitoring of turbidity revealed diel turbidity cycles with peak values during the nighttime and lower values occurring during daytime. Particles responsible for these cycles were fixed suspended solids consisting mostly of aluminosilicates (clay particles) emanating from bed sediments. High-frequency data were used to investigate the transport of total suspended solids (TSS) during base flow. A majority of the base flow TSS loading occurred during the nighttime in a small agricultural catchment in Iowa, United States. Elevated nighttime turbidity coincided with an increased total suspended phosphorus loading during nighttime. Bioturbation, as a result of nocturnal feeding of fishes, is the suspected cause of the diel turbidity cycles. High-frequency monitoring was also used to detect TSS loading during storm events. Results from this study highlight the importance of high-frequency environmental measurements to reveal and understand biogeochemical transport phenomena.

  9. 40 CFR 141.550 - Is my system required to meet subpart T combined filter effluent turbidity limits?

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... utilize filtration other than slow sand filtration or diatomaceous earth filtration must meet the combined... diatomaceous earth filtration you are not required to meet the combined filter effluent turbidity limits...

  10. The relative contribution of processes driving variability in flow, shear, and turbidity over a fringing coral reef: West Maui, Hawaii

    USGS Publications Warehouse

    Storlazzi, C.D.; Jaffe, B.E.

    2008-01-01

    High-frequency measurements of waves, currents and water column properties were made on a fringing coral reef off northwest Maui, Hawaii, for 15 months between 2001 and 2003 to aid in understanding the processes governing flow and turbidity over a range of time scales and their contributions to annual budgets. The summer months were characterized by consistent trade winds and small waves, and under these conditions high-frequency internal bores were commonly observed, there was little net flow or turbidity over the fore reef, and over the reef flat net flow was downwind and turbidity was high. When the trade winds waned or the wind direction deviated from the dominant trade wind orientation, strong alongshore flows occurred into the typically dominant wind direction and lower turbidity was observed across the reef. During the winter, when large storm waves impacted the study area, strong offshore flows and high turbidity occurred on the reef flat and over the fore reef. Over the course of a year, trade wind conditions resulted in the greatest net transport of turbid water due to relatively strong currents, moderate overall turbidity, and their frequent occurrence. Throughout the period of study, near-surface current directions over the fore reef varied on average by more than 41?? from those near the seafloor, and the orientation of the currents over the reef flat differed on average by more than 65?? from those observed over the fore reef. This shear occurred over relatively short vertical (order of meters) and horizontal (order of hundreds of meters) scales, causing material distributed throughout the water column, including the particles in suspension causing the turbidity (e.g. sediment or larvae) and/or dissolved nutrients and contaminants, to be transported in different directions under constant oceanographic and meteorologic forcing.

  11. Modeling turbidity and flow at daily steps in karst using ARIMA/ARFIMA-GARCH error models

    NASA Astrophysics Data System (ADS)

    Massei, N.

    2013-12-01

    Hydrological and physico-chemical variations recorded at karst springs usually reflect highly non-linear processes and the corresponding time series are then very often also highly non-linear. Among others, turbidity, as an important parameter regarding water quality and management, is a very complex response of karst systems to rain events, involving direct transfer of particles from point-source recharge as well as resuspension of particles previously deposited and stored within the system. For those reasons, turbidity modeling has not been well taken in karst hydrological models so far. Most of the time, the modeling approaches would involve stochastic linear models such ARIMA-type models and their derivatives (ARMA, ARMAX, ARIMAX, ARFIMA...). Yet, linear models usually fail to represent well the whole (stochastic) process variability, and their residuals still contain useful information that can be used to either understand the whole variability or to enhance short-term predictability and forecasting. Model residuals are actually not i.i.d., which can be identified by the fact that squared residuals still present clear and significant serial correlation. Indeed, high (low) amplitudes are followed in time by high (low) amplitudes, which can be seen on residuals time series as periods of time during which amplitudes are higher (lower) then the mean amplitude. This is known as the ARCH effet (AutoRegressive Conditional Heteroskedasticity), and the corresponding non-linear process affecting residuals of a linear model can be modeled using ARCH or generalized ARCH (GARCH) non-linear modeling, which approaches are very well known in econometrics. Here we investigated the capability of ARIMA-GARCH error models to represent a ~20-yr daily turbidity time series recorded at a karst spring used for water supply of the city of Le Havre (Upper Normandy, France). ARIMA and ARFIMA models were used to represent the mean behavior of the time series and the residuals clearly

  12. Direct-normal solar irradiance measurements and turbidity coefficient evaluation in central Spain.

    NASA Astrophysics Data System (ADS)

    Bllbao, Julia; Román, Roberto; Miguel, Argimiro

    2013-04-01

    In order to study the characteristics of solar direct radiation and the atmospheric turbidity in Valladolid, Spain, global, diffuse and direct irradiance data were recorded from May 2010 to December 2011, with a frequency of 10 minute. Measurements used were taken by the Energy and Atmosphere Group (http://www3.uva.es/renova), University of Valladolid, Spain at the Solar Radiometric Station (41,81°N 4.93°W, 840m a.s.l.) located on the Atmosphere Researcher Centre, Villalba de los Alcores, Valladolid, Spain. Sensors were installed in a Sun tracker (Solys 2, Kipp & Zonen) that blocks direct solar radiation using a shadow ball. The system consists of two pyranometers CMP-21 and one pyrheliometer CHP-1 (Kipp & Zonen), respectively. Based on these measurements, the characteristics of direct solar irradiance data were evaluated in order to know the main statistical parameters of the distribution. Angström turbidity coefficient values, beta, were estimated from direct solar irradiance and clear sky conditions. The beta coefficient values were obtained from MODIS satellite instrument, and the aerosol optical depth values, AOD(550nm), were evaluated. The turbidity coefficient beta shows seasonal variation, with higher values in summer (< 0.15) and lower in winter (< 0.05). It could be due to high temperatures in summer and less rainy days which would induce more atmospheric turbidity, increasing vertical convection and particles enhancement. The scattered graph of aerosol optical depth from satellite and the obtained from Angström expression has been plotted. The slope presents a value around the unity, 0.96, and the correlation coefficient shows a value of 0.6 . It was observed that turbidity coefficients increased in April 2011, and in order to now the origin the change, air masses trajectories, deduced from HYSPLIT model (http://ready.arl.noaa.gov/HYSPLIT.php) were studied. From the results it has been obtained that a situation of low pressures in the Atlantic

  13. Evaluating the Impacts of Unexpected Forest Disturbances on Paired Catchment Calibrations of Sediment Yield and Turbidity

    NASA Astrophysics Data System (ADS)

    Herlein, K.; Silins, U.; Williams, C.; Wagner, M. J.; Martens, A. M.

    2015-12-01

    The paired catchment approach of studying the impacts of disturbance on catchment hydrology remains as perhaps the most powerful approach for direct verification of catchment scale impacts from disturbance. However, paired catchment studies are also dependent on the stability of the relationships between treated and reference catchments during calibration and evaluation periods. A long-term paired catchment study of forest harvest impacts on sediment yield and turbidity in the Rocky Mountains of southwestern Alberta, Canada has a robust 11-year pre-treatment data record. The study intends to evaluate three alternative logging practices: clear-cutting, strip-shelterwood, and partial cutting. 3 sub-catchments in Star Creek (1035 ha) underwent harvest treatments while North York Creek (865 Ha) serves as the reference. The objective of this particular study was to explore the potential effects of unplanned and unanticipated watershed changes in two watersheds during an 11-year calibration. Sediment yield (kg ha-1 d-1) and turbidity (NTU) were monitored throughout the calibration period (2004-2014) prior to the 2015 harvest in Star Creek. Two unanticipated disturbances including backcountry trail rehabilitation in North York (2010) followed by a >100 year storm event in both watersheds in June 2013 may have affected the sediment yield and turbidity calibration relationships. Analysis of covariance (ANCOVA) was used to evaluate the effects of this trail rehabilitation and flooding by comparing the calibration relationships before and after these disturbances. Despite qualitative field observations of periodically affected sediment regimes, no impact on pre- or post- calibration relationships was observed. Backcountry trail rehabilitation in North York (p=0.904 and 0.416 for sediment yield and turbidity, respectively) or flooding in both watersheds (p=0.364 and 0.204 for sediment yield and turbidity, respectively) did not produce significant changes to the calibrations

  14. Flow Dynamics and Sediment Entrainment in Natural Turbidity Currents Inferred from Numerical Modeling

    NASA Astrophysics Data System (ADS)

    Traer, M. M.; Hilley, G. E.; Fildani, A.

    2009-12-01

    Submarine turbidity currents derive their momentum from gravity acting upon the density contrast between sediment-laden and clear water, and so unlike fluvial systems, the dynamics of such flows are inextricably linked to the rates at which they deposit and entrain sediment. We have analyzed the sensitivity of the growth and maintenance of turbidity currents to sediment entrainment and deposition using the layer-averaged equations of conservation of fluid and sediment mass, and conservation of momentum and turbulent kinetic energy. Our model results show that the dynamics of turbidity currents are extremely sensitive to the functional form and empirical constants of the relationship between sediment entrainment and friction velocity. Data on the relationship between sediment entrainment and friction velocity for submarine density flows are few and as a result, entrainment formulations are populated with data from sub-aerial flows not driven by the density contrast between clear and turbid water. If we entertain the possibility that sediment entrainment in sub-aerial rivers is different than in dense underflows, flow parameters such as velocity, height, and concentration were found nearly impossible to predict beyond a few hundred meters based on the limited laboratory data available that constrain the sediment entrainment process in turbidity currents. The sensitivity of flow dynamics to the functional relationship between friction velocity and sediment entrainment indicates that independent calibration of a sediment entrainment law in the submarine environment is necessary to realistically predict the dynamics of these flows and the resulting patterns of erosion and deposition. To calibrate such a relationship, we have developed an inverse methodology that utilizes existing submarine channel morphology as a means of constraining the sediment entrainment function parameters. We use a Bayesian Metropolis-Hastings sampler to determine the sediment entrainment

  15. Estimation of chlorophyll-a concentration in productive turbid waters using a Hyperspectral Imager for the Coastal Ocean—the Azov Sea case study

    NASA Astrophysics Data System (ADS)

    Gitelson, Anatoly A.; Gao, Bo-Cai; Li, Rong-Rong; Berdnikov, Sergey; Saprygin, Vladislav

    2011-04-01

    We present here the results of chlorophyll-a (chl-a) concentration estimation using the red and near infrared (NIR) spectral bands of a Hyperspectral Imager for the Coastal Ocean (HICO) in productive turbid waters of the Azov Sea, Russia. During the data collection campaign in the summer of 2010 in Taganrog Bay and the Azov Sea, water samples were collected and concentrations of chl-a were measured analytically. The NIR-red models were tuned to optimize the spectral band selections and chl-a concentrations were retrieved from HICO data. The NIR-red three-band model with HICO-retrieved reflectances at wavelengths 684, 700, and 720 nm explained more than 85% of chl-a concentration variation in the range from 19.67 to 93.14 mg m - 3 and was able to estimate chl-a with root mean square error below 10 mg m - 3. The results indicate the high potential of HICO data to estimate chl-a concentration in turbid productive (Case II) waters in real-time, which will be of immense value to scientists, natural resource managers, and decision makers involved in managing the inland and coastal aquatic ecosystems.

  16. Design of chlorophyll-a and turbidity sensor based on fluorescence induction and scattering-light detection

    NASA Astrophysics Data System (ADS)

    Zhang, Keke; Liu, Shixuan; Chen, Shizhe; Qi, Yong; Miao, Bin; Yan, Xingkui; Bai, Xuejiao

    2014-07-01

    The chlorophyll-a and turbidity sensor based on the principles of fluorescence induction and scattering-light detection is designed. Using fluorescence induction technology, scattering-light detection technology and weak signal detection technology, chlorophyll-a concentration measurement and turbidity measurement in seawater are integrated in a set of testing equipment to implement software and hardware reuse and improve the integration of the device, which has the features of small size and easy operation. The comparative experiments and repetitive experiments are completed with ALEC ACLW-CAR chlorophyll / turbidity sensor. Experiment results show that chlorophyll-a concentration, turbidity and the system output values have good linear relationships, and the fitting coefficients are 0.999. Repeatability standard deviations of chlorophyll-a detection and turbidity detection are better than 0.08 μg/L and 0.04 FTU, respectively, and the accuracy of the device within +/- 2%. Chlorophyll-a and turbidity in-situ monitoring in seawater can be achieved using this testing equipment.

  17. Influence of salinity, bottom topography, and tides on locations of estuarine turbidity maxima in northern San Francisco Bay

    USGS Publications Warehouse

    Schoellhamer, David H.

    2000-01-01

    Time series of salinity and suspended-solids concentration measured at four locations and vertical profiles of salinity and suspended-solids concentration measured during 48 water-quality cruises from January 1993 to September 1997 are analyzed to describe the influence of salinity, bottom topography, and tides on locations of estuarine turbidity maxima in northern San Francisco Bay, California. Estuarine turbidity maxima form when salinity is present but they are not associated with a singular salinity. Bottom topography enhances salinity stratification, gravitational circulation and estuarine turbidity maxima formation seaward of sills. The spring/neap tidal cycle affects locations of estuarine turbidity maxima. Salinity stratification in Carquinez Strait, which is seaward of a sill, is greatest during neap tides, which is the only time when tidally averaged suspended-solids concentration in Carquinez Strait was less than that observed landward at Mallard Island. Spring tides cause the greatest vertical mixing and suspended-solids concentration in Carquinez Strait. Therefore, surface estuarine turbidity maxima always were located in or near the Strait (seaward of Middle Ground) during spring tide cruises, regardless of salinity. During neap tides, surface estuarine turbidity maxima always were observed in the landward half of the study area (landward of Middle Ground) and between 0–2 practical salinity units.

  18. Visual Detection of Speckles in the Fish Xenotoca variata by the Predatory Snake Thamnophis melanogaster in Water of Different Turbidity.

    PubMed

    Manjarrez, Javier; Rivas-González, Eric; Venegas-Barrera, Crystian S; Moyaho, Alejandro

    2015-01-01

    Semi-aquatic snakes integrate visual and chemical stimuli, and prey detection and capture success are therefore linked to the display of visual predatory behavior. The snake Thamnophis melanogaster responds preferentially to individuals of the fish Xenotoca variata with a greater number of bright, colorful spots (lateral speckles) compared with those with a smaller number; however, water turbidity can reduce underwater visibility and effect the vulnerability of fish. In this study, we tested whether the presence of iridescent speckles on the flanks of male X. variata interacted with water turbidity to modify the predatory behavior displayed by the snake T. melanogaster. We predicted that in an experimental laboratory test, the snakes would increase the frequency of their predatory behavior to the extent that the water turbidity decreases. The snakes were tested at six different levels of water turbidity, in combination with three categories of male fish (with few, a median number of, or many speckles). The results showed that in a pool with high or zero turbidity, the number of speckles is not a determining factor in the deployment of the predatory behavior of the snake T. melanogaster toward X. variata. Our findings suggest that snakes can view the fish at intermediate percentages of turbidity, but the number of speckles in male X. variata is irrelevant as an interspecific visual signal in environments with insufficient luminosity. The successful capture of aquatic prey is influenced by integration between chemical and visual signals, according to environmental factors that may influence the recognition of individual traits.

  19. On the observability of the fortnightly cycle of the Tagus estuary turbid plume using MODIS ocean colour images

    NASA Astrophysics Data System (ADS)

    Valente, André S.; da Silva, José C. B.

    2009-01-01

    Using three years (2003 to 2005) of MODIS-Aqua normalized water-leaving radiance at 551 nm this paper shows a fortnightly cycle in the Tagus estuary turbid plume. The Tagus estuary is one of the largest estuaries of the west coast of Europe and is located in the most populated area of Portugal, including the capital Lisbon. The turbid plume has been detected by the backscattering characteristics of the surface waters in the vicinity of the estuary mouth. In fortnightly scales, the turbid plume has smaller dimensions during and after neap tides and higher dimensions during and after spring tides. This is most probably associated with the fortnightly spring-neap tidal cycle and the consequent increase in turbidity inside the estuary during spring tides. During the summer weak spring tides (tidal amplitude approximately 2.5 m) no turbid plume is observed for an entire fortnightly cycle. Outside the summer months, precipitation, river discharge and winds, were found to increase the turbid area, but the fortnightly cycle appears to be superimposed on the large time-scale variability, and present throughout the year.

  20. Visual Detection of Speckles in the Fish Xenotoca variata by the Predatory Snake Thamnophis melanogaster in Water of Different Turbidity

    PubMed Central

    Manjarrez, Javier; Rivas-González, Eric; Venegas-Barrera, Crystian S.; Moyaho, Alejandro

    2015-01-01

    Semi-aquatic snakes integrate visual and chemical stimuli, and prey detection and capture success are therefore linked to the display of visual predatory behavior. The snake Thamnophis melanogaster responds preferentially to individuals of the fish Xenotoca variata with a greater number of bright, colorful spots (lateral speckles) compared with those with a smaller number; however, water turbidity can reduce underwater visibility and effect the vulnerability of fish. In this study, we tested whether the presence of iridescent speckles on the flanks of male X. variata interacted with water turbidity to modify the predatory behavior displayed by the snake T. melanogaster. We predicted that in an experimental laboratory test, the snakes would increase the frequency of their predatory behavior to the extent that the water turbidity decreases. The snakes were tested at six different levels of water turbidity, in combination with three categories of male fish (with few, a median number of, or many speckles). The results showed that in a pool with high or zero turbidity, the number of speckles is not a determining factor in the deployment of the predatory behavior of the snake T. melanogaster toward X. variata. Our findings suggest that snakes can view the fish at intermediate percentages of turbidity, but the number of speckles in male X. variata is irrelevant as an interspecific visual signal in environments with insufficient luminosity. The successful capture of aquatic prey is influenced by integration between chemical and visual signals, according to environmental factors that may influence the recognition of individual traits. PMID:26061294

  1. Modulated imaging: A spatial frequency domain imaging method for wide-field spectroscopy and tomography of turbid media

    NASA Astrophysics Data System (ADS)

    Cuccia, David John

    Modulated Imaging (MI) is a fast, scan-free method that enables one to image and quantify the optical properties of turbid media. The technology can simultaneously map surface and sub-surface tissue structure, function and composition. Based on frequency-domain measurement principles, MI uses spatially-periodic or "structured" illumination and camera-based detection to separate and quantify the absorption, scattering, and fluorescence optical properties over a wide field-of-view (many cm) without the need for sample contact. Resolution is depth-dependent and thus scalable (sub-millimeter to millimeter), with depth sensitivity up to a few cm. This method has particularly strong potential for in-vivo clinical and pre-clinical imaging, where optical properties at several wavelengths provide quantitative information on endogeneous chromophore concentrations (i.e. oxy- and deoxy-hemoglobin, fat, and water). These parameters reflect quantitative, localized tissue status such as blood volume, tissue oxygenation, and edema. Using multispectral MI instrumentation, demonstrations of two in-vivo applications are investigated: (1) pre-clinical functional imaging of brain injury in a rodent model and (2) clinical imaging spectroscopy of human skin. Also, preliminary 3D fluorescence tomography data suggest that MI may provide a convenient, low-cost platform for localizing and quantifying exogenous molecular probes in-vivo.

  2. Determination of optical properties of turbid media spanning visible and near-infrared regimes via spatially modulated quantitative spectroscopy.

    PubMed

    Saager, Rolf B; Cuccia, David J; Durkin, Anthony J

    2010-01-01

    We present a novel, noncontact method for the determination of quantitative optical properties of turbid media from 430 to 1050 nm. Through measuring the broadband reflectance from an unknown sample as a function of the spatial frequency of the projected illumination patterns, the absolute absorption and reduced scattering coefficients can be calculated without a priori assumptions of the chromophores present. This technique, which is called spatially modulated quantitative spectroscopy (SMoQS), was validated through the quantification of optical properties of homogenous liquid phantoms with known concentrations of absorbers and scatterers. The properties of the phantoms were recovered across the range of values prepared with R(2) values of 0.985 and 0.996 for absorption and reduced scattering, respectively. A measurement was also performed on skin tissue as a demonstration of the method's performance in vivo. The resultant absorption spectrum was well described by a multichromophore fit, and the quantitative values for oxy- and deoxyhemoglobin, water, and melanin were within published ranges for skin.

  3. Optical model for the water characterization of the highly turbid water of the Winam Gulf (Victoria Lake)

    NASA Astrophysics Data System (ADS)

    Santini, F.; Cavalli, R. M.; Palombo, A.; Pignatti, S.

    2007-10-01

    The study, proposed within the framework of the cooperation with Kenyan Authorities, has been carried out on the Kenyan part of the Lake Victoria. This lake is one of the largest freshwater bodies of the world where, over the last few years, environmental challenges and human impact have perturbed the ecological balance. Pollution and sediments loads from the tributaries rivers and antrophic sources caused a worrying increase of the turbidity level of the lake water. Secchi transparency index has declined from 5 meters in the 1930s to less than one meter in the 1990s. With the aim of providing an inexpensive way to gather information linked to the water clarity and quality, a method for remotely sensed data interpretation, devoted to produce chl (chlorophyll), CDOM (coloured dissolved organic matter) and TSS (total suspended solids) maps, has been assessed. At this purpose a bio-optical model, based on radiative transfer theory in water bodies, has been refined. The method has been applied on an image acquired on January 2004 by ENVISAT/MERIS sensor just a week after an in situ campaign took place. During the in situ campaign a data set for model refinement and products validation has been collected. This data comprise surface radiometric quantity and samples for laboratory analyses. The comparison between the obtained maps and the data provided by the laboratory analysis showed a good correspondence, demonstrating the potentiality of remote observation in supporting the management of the water resources.

  4. Monitoring water turbidity and surface suspended sediment concentration of the Bagre Reservoir (Burkina Faso) using MODIS and field reflectance data

    NASA Astrophysics Data System (ADS)

    Robert, Elodie; Grippa, Manuela; Kergoat, Laurent; Pinet, Sylvain; Gal, Laetitia; Cochonneau, Gérard; Martinez, Jean-Michel

    2016-10-01

    Monitoring turbidity and Surface Suspended Sediment Concentration (SSSC) of inland waters is essential to address several important issues: erosion, sediment transport and deposition throughout watersheds, reservoir siltation, water pollution, human health risks, etc. This is especially important in regions with limited conventional monitoring capacities such as West Africa. In this study, we explore the use of Moderate Resolution Imaging Spectroradiometer data (MODIS, MOD09Q1 and MYD09Q1 products, red (R) and near infrared (NIR) bands) to monitor turbidity and SSSC for the Bagre Reservoir in Burkina Faso. High values ​​of these parameters associated with high spatial and temporal variability potentially challenge the methodologies developed so far for less turbid waters. Field measurements (turbidity, SSSC, radiometry) are used to evaluate different radiometric indices. The NIR/R ratio is found to be the most suited to retrieve SSSC and turbidity for both in-situ spectoradiometer measurements and satellite reflectance from MODIS. The spatio temporal variability of MODIS NIR/R together with rainfall estimated by the Tropical Rainforest Measuring Mission (TRMM) and altimetry data from Jason-2 is analyzed over the Bagre Reservoir for the 2000-2015 period. It is found that rain events of the early rainy season (February-March) through mid-rainy season (August) are decisive in triggering turbidity increase. Sediment transport is observed in the reservoir from upstream to downstream between June and September. Furthermore, a significant increase of 19% in turbidity values is observed between 2000 and 2015, mainly for the July to December period. It is especially well marked for August, with the central and downstream areas showing the largest increase. The most probable hypothesis to explain this evolution is a change in land use, and particularly an increase in the amount of bare soils, which enhances particle transport by runoff.

  5. Performance Evaluation of Different Filter Media in Turbidity Removal from Water by Application of Modified Qualitative Indices

    PubMed Central

    Gholikandi, G Badalians; Dehghanifard, E; Sepehr, M Noori; Torabian, A; Moalej, S; Dehnavi, A; Yari, AR; Asgari, AR

    2012-01-01

    Background Water filtration units have been faced problems in water turbidity removal related to their media, which is determined by qualitative indices. Moreover, Current qualitative indices such as turbidity and escaping particle number could not precisely determine the efficiency of the media in water filtration, so defining new indices is essential. In this study, the efficiency of Anthracite-Silica and LECA-Silica media in turbidity removal were compared in different operating condition by using modified qualitative indices. Methods: The pilot consisted of a filter column (one meter depth) which consisted of a layer of LECA (450 mm depth) and a layer of Silica sand (350 mm depth. Turbidities of 10, 20, and 30 NTU, coagulant concentrations of 4, 8, and 12 ppm and filtration rates of 10, 15, and 20 m/h were considered as variables. Results: The LECA-Silica media is suitable media for water filtration. Averages of turbidity removal efficiencies in different condition for the LECA-Silica media were 85.8±5.37 percent in stable phase and 69.75±3.37 percent in whole operation phase, while the efficiency of total system were 98.31±0.63 and 94.49±2.97 percent, respectively. Conclusion: The LECA layer efficiency in turbidity removal was independent from filtration rates and due to its low head loss; LECA can be used as a proper medium for treatment plants. Results also showed that the particle index (PI) was a suitable index as a substitute for turbidity and EPN indices. PMID:23113169

  6. Sediment and Turbidity Associated with Offshore Dredging Increase Coral Disease Prevalence on Nearby Reefs

    PubMed Central

    Pollock, F. Joseph; Lamb, Joleah B.; Field, Stuart N.; Heron, Scott F.; Schaffelke, Britta; Shedrawi, George; Bourne, David G.; Willis, Bette L.

    2014-01-01

    In recent decades, coral reef ecosystems have declined to the extent that reefs are now threatened globally. While many water quality parameters have been proposed to contribute to reef declines, little evidence exists conclusively linking specific water quality parameters with increased disease prevalence in situ. Here we report evidence from in situ coral health surveys confirming that chronic exposure to dredging-associated sediment plumes significantly increase the prevalence of white syndromes, a devastating group of globally important coral diseases. Coral health surveys were conducted along a dredging-associated sediment plume gradient to assess the relationship between sedimentation, turbidity and coral health. Reefs exposed to the highest number of days under the sediment plume (296 to 347 days) had two-fold higher levels of disease, largely driven by a 2.5-fold increase in white syndromes, and a six-fold increase in other signs of compromised coral health relative to reefs with little or no plume exposure (0 to 9 days). Multivariate modeling and ordination incorporating sediment exposure level, coral community composition and cover, predation and multiple thermal stress indices provided further confirmation that sediment plume exposure level was the main driver of elevated disease and other compromised coral health indicators. This study provides the first evidence linking dredging-associated sedimentation and turbidity with elevated coral disease prevalence in situ. Our results may help to explain observed increases in global coral disease prevalence in recent decades and suggest that minimizing sedimentation and turbidity associated with coastal development will provide an important management tool for controlling coral disease epizootics. PMID:25029525

  7. Impacts of Sediments on Coral Energetics: Partitioning the Effects of Turbidity and Settling Particles

    PubMed Central

    Junjie, Reef K.; Browne, Nicola K.; Erftemeijer, Paul L. A.; Todd, Peter A.

    2014-01-01

    Sediment loads have long been known to be deleterious to corals, but the effects of turbidity and settling particles have not previously been partitioned. This study provides a novel approach using inert silicon carbide powder to partition and quantify the mechanical effects of sediment settling versus reduced light under a chronically high sedimentary regime on two turbid water corals commonly found in Singapore (Galaxea fascicularis and Goniopora somaliensis). Coral fragments were evenly distributed among three treatments: an open control (30% ambient PAR), a shaded control (15% ambient PAR) and sediment treatment (15% ambient PAR; 26.4 mg cm−2 day−1). The rate of photosynthesis and respiration, and the dark-adapted quantum yield were measured once a week for four weeks. By week four, the photosynthesis to respiration ratio (P/R ratio) and the photosynthetic yield (Fv/Fm) had fallen by 14% and 3–17% respectively in the shaded control, contrasting with corals exposed to sediments whose P/R ratio and yield had declined by 21% and 18–34% respectively. The differences in rates between the shaded control and the sediment treatment were attributed to the mechanical effects of sediment deposition. The physiological response to sediment stress differed between species with G. fascicularis experiencing a greater decline in the net photosynthetic yield (13%) than G. somaliensis (9.5%), but a smaller increase in the respiration rates (G. fascicularis = 9.9%, G. somaliensis = 14.2%). These different physiological responses were attributed, in part, to coral morphology and highlighted key physiological processes that drive species distribution along high to low turbidity and depositional gradients. PMID:25197883

  8. Sediment and turbidity associated with offshore dredging increase coral disease prevalence on nearby reefs.

    PubMed

    Pollock, F Joseph; Lamb, Joleah B; Field, Stuart N; Heron, Scott F; Schaffelke, Britta; Shedrawi, George; Bourne, David G; Willis, Bette L

    2014-01-01

    In recent decades, coral reef ecosystems have declined to the extent that reefs are now threatened globally. While many water quality parameters have been proposed to contribute to reef declines, little evidence exists conclusively linking specific water quality parameters with increased disease prevalence in situ. Here we report evidence from in situ coral health surveys confirming that chronic exposure to dredging-associated sediment plumes significantly increase the prevalence of white syndromes, a devastating group of globally important coral diseases. Coral health surveys were conducted along a dredging-associated sediment plume gradient to assess the relationship between sedimentation, turbidity and coral health. Reefs exposed to the highest number of days under the sediment plume (296 to 347 days) had two-fold higher levels of disease, largely driven by a 2.5-fold increase in white syndromes, and a six-fold increase in other signs of compromised coral health relative to reefs with little or no plume exposure (0 to 9 days). Multivariate modeling and ordination incorporating sediment exposure level, coral community composition and cover, predation and multiple thermal stress indices provided further confirmation that sediment plume exposure level was the main driver of elevated disease and other compromised coral health indicators. This study provides the first evidence linking dredging-associated sedimentation and turbidity with elevated coral disease prevalence in situ. Our results may help to explain observed increases in global coral disease prevalence in recent decades and suggest that minimizing sedimentation and turbidity associated with coastal development will provide an important management tool for controlling coral disease epizootics.

  9. Mitigation of turbidity currents in reservoirs with passive retention systems: validation of CFD modeling

    NASA Astrophysics Data System (ADS)

    Ferreira, E.; Alves, E.; Ferreira, R. M. L.

    2012-04-01

    Sediment deposition by continuous turbidity currents may affect eco-environmental river dynamics in natural reservoirs and hinder the maneuverability of bottom discharge gates in dam reservoirs. In recent years, innovative techniques have been proposed to enforce the deposition of turbidity further upstream in the reservoir (and away from the dam), namely, the use of solid and permeable obstacles such as water jet screens , geotextile screens, etc.. The main objective of this study is to validate a computational fluid dynamics (CFD) code applied to the simulation of the interaction between a turbidity current and a passive retention system, designed to induce sediment deposition. To accomplish the proposed objective, laboratory tests were conducted where a simple obstacle configuration was subjected to the passage of currents with different initial sediment concentrations. The experimental data was used to build benchmark cases to validate the 3D CFD software ANSYS-CFX. Sensitivity tests of mesh design, turbulence models and discretization requirements were performed. The validation consisted in comparing experimental and numerical results, involving instantaneous and time-averaged sediment concentrations and velocities. In general, a good agreement between the numerical and the experimental values is achieved when: i) realistic outlet conditions are specified, ii) channel roughness is properly calibrated, iii) two equation k - ɛ models are employed iv) a fine mesh is employed near the bottom boundary. Acknowledgements This study was funded by the Portuguese Foundation for Science and Technology through the project PTDC/ECM/099485/2008. The first author thanks the assistance of Professor Moitinho de Almeida from ICIST and to all members of the project and of the Fluvial Hydraulics group of CEHIDRO.

  10. Dynamic control of coherent orbital-angular-momentum beams in turbid environments

    NASA Astrophysics Data System (ADS)

    Morgan, K. S.; Miller, J. K.; Cochenour, B. M.; Johnson, E. G.

    2016-05-01

    This work examines the propagation properties of two superimposed coherent orbital angular momentum (OAM) modes for use in underwater systems as an alternative to amplitude modulation. An OAM mode of l=+2 is interfered with OAM mode l=-1 from a λ = 540 nm laser source. These OAM modes are superimposed using a Mach-Zehnder (MZ) interferometer combined with diffractive optical elements. By manipulating the optical path length of one of the MZ legs, the interference of these beams can be temporally controlled. The spatial profile is maintained in a turbid environment up through 4.9 attenuation lengths for both cases.

  11. Measurement of the refractive index of highly turbid media: reply to comment.

    PubMed

    Calhoun, W; Maeta, H; Combs, A; Bali, L M; Bali, S

    2011-08-15

    Peiponen et al. [Opt. Lett.35, 4108 (2010)] have expressed concern that a theoretical model we proposed in Calhoun et al. [Opt. Lett.35, 1224 (2010)] for total internal reflection from a turbid medium may be inconsistent with the experimental data, in the sense that the model fails to take into account unexplained oscillations in our data. We show that their concern arises from misinterpretation of our data and theory, and is, therefore, unfounded. NOTE: Optics Letters apologizes to the authors for the delay in the publication of this Reply.

  12. Modification of the vertically generalized production model for the turbid waters of Ariake Bay, southwestern Japan

    NASA Astrophysics Data System (ADS)

    Tripathy, S. C.; Ishizaka, J.; Siswanto, E.; Shibata, T.; Mino, Y.

    2012-01-01

    The vertically generalized production model (VGPM), which was designed for open ocean waters ( Behrenfeld and Falkowski, 1997a; henceforth BF), was evaluated using in situ measurements of primary productivity (PP) in the characteristically turbid coastal waters of Ariake Bay, southwestern Japan, to develop a regionally modified version of the model. The euphotic depth ( Z eu)-integrated PP (IPP) calculated from the VGPM using in situ chlorophyll a (Chl a) and sea surface temperature (SST) was significantly overestimated (by factors of 2-3), but 52% of the observed variability was explained. The weak correlation could have partially resulted from overestimations by the sub-models embedded in the original VGPM model for estimation of Z eu ( Morel and Berthon, 1989; henceforth MB) and the optimal Chl a-normalized PP ( poptB). The sub-model estimates of poptB and Z eu with in situpoptB and Z eu showed significant improvement, accounting for 84% of the variability and causing less overestimation. Z eu was the most important parameter influencing the modeled IPP variation in Ariake Bay. Previous research suggested that the Z eu model, which was based on surface Chl a, overestimated in situ Z eu by a factor of 2-3, resulting in weak correlation between the modeled and in situ IPP. The Z eu sub-model was not accurate in the present study area because it was basically developed for clear (case 1) waters. A better estimation of Z eu could be obtained from the in situ remote sensing reflectance ( R rs) using a quasi-analytical algorithm (QAA) in this turbid water ecosystem. Among the parameters of PP models, poptB is conventionally considered the most important. However, in this study poptB was of secondary importance because the contribution of poptB to the variation in modeled IPP was less than the contribution of Z eu. The modeled and in situpoptB were weakly correlated with 50% of the data points that overestimated the in situ values. The estimation of Chl a was improved

  13. Three-dimensional localization of fluorescent targets in turbid media using time reversal optical tomography

    NASA Astrophysics Data System (ADS)

    Wu, Binlin; Cai, W.; Gayen, S. K.

    2012-12-01

    An optical tomography approach for locating fluorescent targets embedded inside a turbid medium is introduced. It uses multi-source probing and multi-detector signal acquisition to collect diffuse fluorescence signal, and time reversal matrix formalism with subspace based signal processing for image reconstruction. It could provide three-dimensional position co-ordinates of two small fluorescent targets embedded in Intralipid-20% suspension of thickness ˜60 times the transport mean free path with an accuracy of ˜1 mm. Fast reconstruction and high spatial resolution make the approach potentially suited for detecting and locating contrast-enhanced breast tumor at early stages of growth.

  14. Microscopy imaging and quantitative phase contrast mapping in turbid microfluidic channels by digital holography.

    PubMed

    Paturzo, Melania; Finizio, Andrea; Memmolo, Pasquale; Puglisi, Roberto; Balduzzi, Donatella; Galli, Andrea; Ferraro, Pietro

    2012-09-07

    We show that sharp imaging and quantitative phase-contrast microcopy is possible in microfluidics in flowing turbid media by digital holography. In fact, in flowing liquids with suspended colloidal particles, clear vision is hindered and cannot be recovered by any other microscopic imaging technique. On the contrary, using digital holography, clear imaging is possible thanks to the Doppler frequency shift experienced by the photons scattered by the flowing colloidal particles, which do not contribute to the interference process, i.e. the recorded hologram. The method is illustrated and imaging results are demonstrated for pure phase objects, i.e. biological cells in microfluidic channels.

  15. A deep water turbidity origin for the Altuda Formation (Capitanian, Permian), Northwest Glass Mountains, Texas

    USGS Publications Warehouse

    Haneef, Mohammad; Rohr, D.M.; Wardlaw, B.R.

    2000-01-01

    The Altuda Formation (Capitanian) in the northwestern Glass Mountains is comprised of thin, even bedded limestones, dolostones, mixed clastic-carbonates, and silt/sandstones interbedded with basin-ward dipping wedge-shaped clinoforms of the Captian Limestone. The formation is characterized by graded bedding, planar laminations, flame structures, contorted/convolute bedding, horizontal branching burrows, and shelf-derived normal marine fauna. A detailed study of the Altuda Formation north of Old Blue Mountain, Glass Mountains, reveals that the formation in this area was deposited by turbidity currents in slope to basinal settings.

  16. Measurement of high turbidity water behavior by ADCP at Izena Caldera in Okinawa Trough

    NASA Astrophysics Data System (ADS)

    Furuta, S.; Arai, R.; Yamazaki, T.

    2012-12-01

    Hydrothermal processes associated with spreading centers of plate-tectonics form hydrothermal activities and the resulted seafloor massive sulfide (SMS) deposits. Given that the SMS deposits found in the western Pacific have been considered to be potential sources of gold, silver, copper, zinc, and lead, there is a strong possibility that they will be mined near future. In order to take measures against environmental impacts during the mining of SMS deposits, it is important to measure components of hydrothermal origin with high temporal and spatial resolution on site, and to understand the mass circulation and transfer systems around the mining area. The Acoustic Doppler Current Profiler (ADCP) is effective tool for measurement of current field in water column in general. In addition, it is also useful for detection of turbidity profile in the water column simultaneously, applying an acoustic propagation model to the data. Izena Caldera, which is 3 km in short, 6 km in long axes and is generically from1,600 m to 1,700 m in depth, is located at the northwest of Okinawa Island. There both attractive SMS deposits and active hydrothermal vent systems have been confirmed. Because of the active vent systems and a bowl-like geographical structure, a quite unique mass circulation and transfer background condition is expected in Izena Caldera. The mining operation will add plenty of suspended materials into the background condition. For a primary understanding of the background condition, the authors analyzed the ADCP data and found two high-turbidity water zones in Izena Caldera and their behavior relationships with the current structure. The vertical downward current affects one of the high-turbidity zones around 1,220 m in depth. The current velocity against north-south direction and east-west direction affects the other high-turbidity zone 1,550 m in depth. Also the zones are recognized the higher synchronization with the lumi-solar diurnal tide, about 24 hours. The

  17. Equivalence of four Monte Carlo methods for photon migration in turbid media.

    PubMed

    Sassaroli, Angelo; Martelli, Fabrizio

    2012-10-01

    In the field of photon migration in turbid media, different Monte Carlo methods are usually employed to solve the radiative transfer equation. We consider four different Monte Carlo methods, widely used in the field of tissue optics, that are based on four different ways to build photons' trajectories. We provide both theoretical arguments and numerical results showing the statistical equivalence of the four methods. In the numerical results we compare the temporal point spread functions calculated by the four methods for a wide range of the optical properties in the slab and semi-infinite medium geometry. The convergence of the methods is also briefly discussed.

  18. Novel approach for simultaneous sediment classification and concentration determination of water turbidity

    NASA Astrophysics Data System (ADS)

    Duarte, Daniel P.; Prats, Sergio; Keizer, J. J.; Georgieva, Petia; Nogueira, Rogério; Bilro, Lúcia

    2015-09-01

    A new approach for data analysis and classification for datasets obtained by a multiparameter optical turbidity sensor is proposed. This approach is based on the combination of statistical or machine learning methods such as linear regressions and clustering analysis. A case study is presented using a 6 dimensional fiber optic sensor to simultaneously classify types of sediments and concentration. Results show a 79% of success for the used training data sets. The methodology proposed is flexible because can be easily adapted to other physical scenarios.

  19. Spatial evolution of depolarization in homogeneous turbid media within the differential Mueller matrix formalism.

    PubMed

    Agarwal, Naman; Yoon, Jiho; Garcia-Caurel, Enric; Novikova, Tatiana; Vanel, Jean-Charles; Pierangelo, Angelo; Bykov, Alexander; Popov, Alexey; Meglinski, Igor; Ossikovski, Razvigor

    2015-12-01

    We show, through visible-range Mueller polarimetry, as well as numerical simulations, that the depolarization in a homogeneous turbid medium consisting of submicron spherical particles follows a parabolic law with the path-length traveled by light through the medium. This result is in full agreement with the phenomenological theory of the fluctuating medium within the framework of the differential Mueller matrix formalism. We further found that the standard deviations of the fluctuating elementary polarization properties of the medium depend linearly on the concentration of particles. These findings are believed to be useful for the phenomenological interpretation of polarimetric experiments, with special emphasis on biomedical applications.

  20. A comparison of observed and analytically derived remote sensing penetration depths for turbid water

    NASA Technical Reports Server (NTRS)

    Morris, W. D.; Usry, J. W.; Witte, W. G.; Whitlock, C. H.; Guraus, E. A.

    1981-01-01

    The depth to which sunlight will penetrate in turbid waters was investigated. The tests were conducted in water with a single scattering albedo range, and over a range of solar elevation angles. Two different techniques were used to determine the depth of light penetration. It showed little change in the depth of sunlight penetration with changing solar elevation angle. A comparison of the penetration depths indicates that the best agreement between the two methods was achieved when the quasisingle scattering relationship was not corrected for solar angle. It is concluded that sunlight penetration is dependent on inherent water properties only.

  1. Measuring the scattering coefficient of turbid media from two-photon microscopy.

    PubMed

    Sevrain, David; Dubreuil, Matthieu; Leray, Aymeric; Odin, Christophe; Le Grand, Yann

    2013-10-21

    In this paper, we propose a new and simple method based on two-photon excitation fluorescence (TPEF) microscopy to measure the scattering coefficient µ(s) of thick turbid media. We show, from Monte Carlo simulations, that µ(s) can be derived from the axial profile of the ratio of the TPEF signals epi-collected by the confocal and the non-descanned ports of a scanning microscope, independently of the anisotropy factor g and of the absorption coefficient µ(a) of the medium. The method is validated experimentally on tissue-mimicking optical phantoms, and is shown to have potential for imaging the scattering coefficient of heterogeneous media.

  2. Tagging photons with gold nanoparticles as localized absorbers in optical measurements in turbid media

    PubMed Central

    Grabtchak, Serge; Callaghan, Kristen B.; Whelan, William M.

    2013-01-01

    We analyze a role of a localized inclusion as a probe for spatial distributions of migrating photons in turbid media. We present new experimental data and two-dimensional analysis of radiance detection of a localized absorptive inclusion formed by gold nanoparticles in Intralipid-1% when the target is translated along the line connecting the light source and detector. Data are analyzed using the novel analytical expression for the relative angular photon distribution function for radiance developed by extending the perturbation approach for fluence. Obtained photon maps allow predicting conditions for detectability of inclusions for which proximity to the detector is essential. PMID:24409396

  3. Influence of long-term sediment transport on contaminant dispersal in a turbid estuary

    NASA Astrophysics Data System (ADS)

    Uncles, R. J.; Woodrow, T. Y.; Stephens, J. A.

    1987-11-01

    Theoretical calculations are made of the long-term transport of fine sediment in a turbid estuary, and its possible consequences for the tidally averaged distribution of a contaminant whose partitioning between dissolved and particulate phases is dependent on salinity. It is found that the partitioning has a crucial effect on the levels of dissolved contaminant, in agreement with the observations of MORRIS (1986, The Science of the Total Environment, 49, 297-304). Calculations also imply that the vertical fluxes of particulate contaminant between water column and bed have a profound influence on these levels.

  4. Study of turbidity Simulation in an oxbow lake considering sediment particle distribution

    NASA Astrophysics Data System (ADS)

    Yokoyama, H.; Murase, T.; Yamashita, S.

    2009-12-01

    We have conducted study on developing water quality simulation model for an oxbow lake close to large city. Pollution load have been flown into the oxbow. So the sediment containing much nutrient and organic matter has been accumulated on the bed. It is well known that resuspension of sediment is a major resource of phosphorus, which once caused algal bloom in this oxbow. Therefore, resuspension rate and sedimentation rate are important parameters for improving water quality simulation accuracy. We tried to quantify these parameters. We had conducted field observation and laboratory test to understand mechanism and process of resuspension and sedimentation. Mass of resuspension was examined on some observation sites by collecting falling particles into sediment traps. Correlation between resuspension rate and wind velocity was investigated. Correlation between resuspension rate and wind velocity is confirmed in upstream site. However, it was not confirmed in downstream site. Sedimentation rate was investigated in two different methods: sediment trap observation and bed material sedimentation test. Correlations among sediment particle size, density and fall velocity were examined. Sedimentation rates have little correlation with neither particle size nor density in sediment trap test. But in sedimentation tests, falling process of particle can be classified into three different motions. (1)Particles larger than 0.075mm (defined as sand) reach bed rapidly so they can be assumed to follow Stokes’ law of soil. (2)Particles smaller than 0.010mm falls very slowly so they can be assumed to keep suspended and can be treated as base turbidity. (3)Other particles obey to Stokes’ law, but density was smaller than soil and it depends on particle size. The resuspension and sedimentation model was developed based on these tests. Next water quality simulation was based on 2-D vertical model was conducted. Mixed-size sediment particle was considered in turbidity calculation

  5. An empirical formula based on Monte Carlo simulation for diffuse reflectance from turbid media

    NASA Astrophysics Data System (ADS)

    Gnanatheepam, Einstein; Aruna, Prakasa Rao; Ganesan, Singaravelu

    2016-03-01

    Diffuse reflectance spectroscopy has been widely used in diagnostic oncology and characterization of laser irradiated tissue. However, still accurate and simple analytical equation does not exist for estimation of diffuse reflectance from turbid media. In this work, a diffuse reflectance lookup table for a range of tissue optical properties was generated using Monte Carlo simulation. Based on the generated Monte Carlo lookup table, an empirical formula for diffuse reflectance was developed using surface fitting method. The variance between the Monte Carlo lookup table surface and the surface obtained from the proposed empirical formula is less than 1%. The proposed empirical formula may be used for modeling of diffuse reflectance from tissue.

  6. Experimental study on cyclic steps formed by surge-type turbidity currents

    NASA Astrophysics Data System (ADS)

    Yokokawa, M.; Shozakai, D.; Higuchi, H.; Hughes Clarke, J. E.; Izumi, N.

    2015-12-01

    Field observations of turbidity currents and seabed topography on the Squamish delta in Howe Sound, British Columbia, Canada have been undertaken which found bedwaves actively migrating in the upstream direction in channels formed on the prodelta slope (Hughes Clarke et al., 2012a; 2012b; 2014; Figure 1). Their topography and behaviour suggest that they are cyclic steps formed by the surge-type turbidity currents. There has been no experimental study to investigate the formative conditions of cyclic steps by the surge-type turbidity currents. We did preliminary experiments on the formation of cyclic steps due to the multiple surge-type density currents, and compare the morphology of the steps with those of Squamish delta. The experiments had been performed at Osaka Institute of Technology. A flume, which is 3.6 m long, 0.3 m deep and 2 cm wide, was submerged into a larger flume, which is 4 m long, 0.4 m deep and 8 cm wide, filled with water. Mixture of salt water (1.18 g/cm3) and plastic particles (1.5 g/cm3, 0.1-0.18 mm in diameter) poured into the upstream end of the inner flume by hand using a funnel. For the example introduced here, the slope of the outer flume was 1.5 degrees, and the mixtures' whole weight and volumetric concentration ranged from 310 g (3.23 vol.%) to 510 g (8.16 vol.%). These mixtures were poured 105 times, and the thickness of the deposits was measured every 50 cm by photographs. As a result, two mounds (steps) were formed ultimately, which are moving toward upstream direction. Wavelengths are 80 cm and 120 cm respectively. The two kinds of flow depth were measured from photograph, such as the whole thickness of the flow, and the thickness of the lower high-density layer. Calculating the wave steepness and non-dimensional wave number, it turns out that those values using the thickness of the lower high-density layer fall into the region very close to the Squamish data that assuming the flow depth as 0.5 m. This could lead the following

  7. A multi-instrument approach to monitoring turbidity currents: Case study from the Squamish Delta, British Columbia (Canada)

    NASA Astrophysics Data System (ADS)

    Hage, Sophie; Cartigny, Matthieu; Clare, Michael; Talling, Peter; Sumner, Esther; Vardy, Mark; Hughes Clarke, John

    2016-04-01

    Turbidity currents are volumetrically the most important process for moving sediment in submarine environments. They may travel at high speeds, thereby posing a threat to important and expensive seafloor infrastructure. Despite their importance, we still know little about their flow dynamics because direct monitoring is challenging and consequently rare. Additionally, the few settings in which monitoring has been feasible, have generally involved a single instrument approach, either measuring flow velocity, sediment concentration or grain size. Here we present results issued from a multi-instrument study where a single turbidity current was observed with several instruments at the same location and time using different measuring frequencies. Three types of geophysical sensors were deployed from a single vessel moored over a turbidity current channel on the Squamish Delta in British Colombia, Canada. First, two 500 kHz multibeam sonars suspended from the bow of the ship imaged the incoming turbidity current and documented its interaction with the crescentic bedforms on the channel thalweg. Second, a 600 kHz downward-looking Acoustic Doppler Current Profiler (ADCP) lowered from the back of the ship provided vertical profiles of velocity through time. Third, a 1.0-24.0 kHz Chirp profiler enabled for the first time imaging of the dense near-bed zone of the turbidity current, which has so far been largely impenetrable using higher frequency sonar and ADCP instruments. Besides the stationary deployment, a repetitive multibeam survey was also performed using a moving vessel in order monitor temporal evolution of the seafloor morphology resulting from turbidity currents. By combining the measurements from each system, a single turbidity current was characterised in unusually high resolution. This current was 6 to 8 meters thick and at least 40 meters wide according to the multibeam sonars. The ADCP measured a front speed of around 1.5 m/s, higher than the internal

  8. Monitoring the onset, propagation, associated bedform migration, and wake of active turbidity currents on the Squamish prodelta slope

    NASA Astrophysics Data System (ADS)

    Hughes Clarke, J. E.; Pratomo, D. G.; Videira Marques, C. R.

    2012-12-01

    . Multibeam water column imagery is used to view the onset, development and decay of turbidity currents in channels on the Squamish prodelta slope. The 2011 program consisted of daily resurveys for a period of 120 days during the freshet period. The initial focus was on resolving bathymetric surface change. Typical morphologic change indicated intermittent upslope migration of in-channel bedforms, sometimes, but not always, associated with an upper slope discrete slide scar. As a serendipitous byproduct, it was found that the deep scattering layer in the fjord was occasionally perturbed by what appeared to be bottom-following intrusive flows. A distally-located, seabed-mounted ADCP confirmed 20 discrete turbidity current events. Surface lowered, optical backscatter profiles indicated that these intrusions were correlated with near-seabed turbidity peaks. In 2012, a week-long program was implemented using hourly resurveys of the channels around the low water spring tide periods. Repetitive underway optical backscatter and CTD profiles were collected extending along the active channels from the delta lip to 1000m offshore. These established the sediment load and relative buoyancy of the surface plume and the fact that the enhanced acoustic volume scattering below represented a descending rain of suspended sediments into the higher density saline lower layers. For several of the events, that descending plume was seen to markedly increase in turbidity close to the seabed, indicating a transition to hyperpycnal conditions. A drop of salinity was also associated with those near seabed high turbidity layers. Those events were followed by the onset of a turbidity current as interpreted from the acoustic volume scattering. The period of upslope bedform migration was restricted to the onset of basal turbidity and first appearance of the flow in the acoustic volume scattering. In the wake of the active flow, an anomalously low acoustic scattering cloud would appear above the

  9. Using Relevance Vector Machines Approach for Prediction of Total Suspended Solids and Turbidity to Sustain Water Quality

    NASA Astrophysics Data System (ADS)

    Batt, H. A.

    2011-12-01

    The study of sediment transport in water bodies is a challenging task. There have been several attempts to describe sediment dynamics mathematically using the hydraulic characteristics of water bodies. Most researchers who developed empirical formulas to describe sediment transport performed laboratory experiments with assumptions that didn't take into account the variation of hydraulic parameters, and fine sediment sizes that are a major part of this phenomenon. New approaches for studying sediment transport have been developed recently involving the use of machine learning algorithms that have proven accuracy and efficiency in predicting sediment transport. A novel machine learning method, the Relevance Vector Machine (RVM),hasn't been tested yet to model sediment transport in estuaries and lakes.RVM are statistical learning algorithms that have been used to predict patterns in hydrological systems as well as in other fields. Development of RVM to predict sediment transport and spatial distribution requires representative samples, and information concerning sediment deposition patterns. Mud Lake is a wildlife refuge located in southeastern Idaho just north of Bear Lake that traps sediment from the Bear River , prior to its flowing into Bear Lake. Spatial patterns of sediment deposition may affect lake flows and habitat; prediction of those patterns should help refuge managers sustain the purposes for which Mud Lake was created.Sediment samples collected in summer 2009 that support the hypothesis of patterns based on spatial location, and topographic, hydraulic, and other data are presented, and their use to develop the RVM model is described.Modeling of the hydrodynamics and data collected during 2009/ 2010 show representative patterns between all water quality measures and turbidity, based on spatial location and topography. Here we describe data collection efforts in 2010 to compare with 2009, as well as hydrodynamic modeling that support the hypothesis of

  10. Turbid Bottom Waters and Ammonium-Rich Freshwaters as Nitrification Hotspots in a Large Urban Estuary (San Francisco Bay, CA)

    NASA Astrophysics Data System (ADS)

    Damashek, J.; Casciotti, K. L.; Francis, C.

    2015-12-01

    Nitrification is the link between reduced and oxidized forms of inorganic nitrogen, and is therefore a crucial step in the estuarine nitrogen cycle. Ammonia-oxidizing microorganisms catalyze the rate-limiting step of ammonia oxidation to nitrite and thus play key roles in the biogeochemical cycling nutrient-rich estuaries. Yet, few studies have measured nitrification rates in tandem with ammonia oxidizer functional gene (amoA) expression, abundance, and diversity in estuary waters. Here, we present a multi-year data set on the microbial ecology and biogeochemistry of nitrification in the San Francisco Bay-Delta, the largest estuary on the North American west coast, collected throughout all regions of the estuary from 2012 to 2014. Data on microbial community distributions use functional gene-based PCR assays to assess the diversity, abundance, and mRNA expression of ammonia oxidizers, while stable isotope tracer experiments were used to measure nitrification rates. Ammonia-oxidizing archaea (AOA) typically outnumbered ammonia-oxidizing bacteria (AOB) throughout the sampled gradient, though the relative abundance of AOB was often greater in brackish regions. mRNA expression of amoA appeared to largely track DNA abundance, but suggested only a fraction of the ammonia-oxidizing community was typically active. AOA were always numerically dominant in the Sacramento River, where average nitrification rates were highest, suggesting the AOA communities in this river are responsible for a relatively constant nitrification hotspot. Additionally, depth profiles of nitrification rates suggested high biogeochemical activity near the sediment-water interface in samples with abnormally high turbidity, indicating similar but transient nitrification hotspots in bottom waters containing resuspended sediments. This work increases our knowledge of the ecology and dynamics of ammonia oxidizers in the San Francisco Bay-Delta, with time series data allowing for the putative

  11. Computing time-series suspended-sediment concentrations and loads from in-stream turbidity-sensor and streamflow data

    USGS Publications Warehouse

    Rasmussen, Patrick P.; Gray, John R.; Glysson, G. Doug; Ziegler, Andrew C.

    2010-01-01

    Over the last decade, use of a method for computing suspended-sediment concentration and loads using turbidity sensors—primarily nephelometry, but also optical backscatter—has proliferated. Because an in- itu turbidity sensor is capa le of measuring turbidity instantaneously, a turbidity time series can be recorded and related directly to time-varying suspended-sediment concentrations. Depending on the suspended-sediment characteristics of the measurement site, this method can be more reliable and, in many cases, a more accurate means for computing suspended-sediment concentrations and loads than traditional U.S. Geological Survey computational methods. Guidelines and procedures for estimating time s ries of suspended-sediment concentration and loading as a function of turbidity and streamflow data have been published in a U.S. Geological Survey Techniques and Methods Report, Book 3, Chapter C4. This paper is a summary of these guidelines and discusses some of the concepts, s atistical procedures, and techniques used to maintain a multiyear suspended sediment time series.

  12. Assessing predation risks for small fish in a large river ecosystem between contrasting habitats and turbidity conditions

    USGS Publications Warehouse

    Dodrill, Michael J.; Yard, Mike; Pine, William E.

    2016-01-01

    This study examined predation risk for juvenile native fish between two riverine shoreline habitats, backwater and debris fan, across three discrete turbidity levels (low, intermediate, high) to understand environmental risks associated with habitat use in a section of the Colorado River in Grand Canyon, AZ. Inferences are particularly important to juvenile native fish, including the federally endangered humpback chub Gila cypha. This species uses a variety of habitats including backwaters which are often considered important rearing areas. Densities of two likely predators, adult rainbow trout Oncorhynchus mykiss and adult humpback chub, were estimated between habitats using binomial mixture models to examine whether higher predator density was associated with patterns of predation risk. Tethering experiments were used to quantify relative predation risk between habitats and turbidity conditions. Under low and intermediate turbidity conditions, debris fan habitat showed higher relative predation risk compared to backwaters. In both habitats the highest predation risk was observed during intermediate turbidity conditions. Density of likely predators did not significantly differ between these habitats. This information can help managers in Grand Canyon weigh flow policy options designed to increase backwater availability or extant turbidity conditions.

  13. Performance assessment of a commonly used "accumulation and wash-off" model from long-term continuous road runoff turbidity measurements.

    PubMed

    Sage, Jérémie; Bonhomme, Céline; Al Ali, Saja; Gromaire, Marie-Christine

    2015-07-01

    The suitability of a commonly used accumulation and wash-off model for continuous modelling of urban runoff contamination was evaluated based on 11-month turbidity and flow-rate records from an urban street. Calibration and uncertainty analysis were performed using a Markov Chain Monte-Carlo sampling method for both suspended solids loads (discharge rates) and concentration modelling. Selected models failed at replicating suspended solids concentration over the complete monitoring period. The studied dataset indeed suggests that the accumulation process is rather unpredictable and cannot be satisfactorily represented with usual accumulation models unless short periods are considered. Regarding suspended solid loads modelling, noticeably better performance was achieved, but similar results could as well be obtained with much simpler constant concentration models. Unless providing very accurate estimates of concentrations in runoff, accounting for their temporal variability during rain events may therefore not always be necessary for pollutant loads modelling, as loads are in fact mostly explained by runoff volumes.

  14. Assessments at multiple levels of biological organization allow for an integrative determination of physiological tolerances to turbidity in an endangered fish species

    PubMed Central

    Hasenbein, Matthias; Fangue, Nann A.; Geist, Juergen; Komoroske, Lisa M.; Truong, Jennifer; McPherson, Rina; Connon, Richard E.

    2016-01-01

    Turbidity can influence trophic levels by altering species composition and can potentially affect fish feeding strategies and predator–prey interactions. The estuarine turbidity maximum, described as an area of increased suspended particles, phytoplankton and zooplankton, generally represents a zone with higher turbidity and enhanced food sources important for successful feeding and growth in many fish species. The delta smelt (Hypomesus transpacificus) is an endangered, pelagic fish species endemic to the San Francisco Estuary and Sacramento–San Joaquin River Delta, USA, where it is associated with turbid waters. Turbidity is known to play an important role for the completion of the species' life cycle; however, turbidity ranges in the Delta are broad, and specific requirements for this fish species are still unknown. To evaluate turbidity requirements for early life stages, late-larval delta smelt were maintained at environmentally relevant turbidity levels ranging from 5 to 250 nephelometric turbidity units (NTU) for 24 h, after which a combination of physiological endpoints (molecular biomarkers and cortisol), behavioural indices (feeding) and whole-organism measures (survival) were determined. All endpoints delivered consistent results and identified turbidities between 25 and 80 NTU as preferential. Delta smelt survival rates were highest between 12 and 80 NTU and feeding rates were highest between 25 and 80 NTU. Cortisol levels indicated minimal stress between 35 and 80 NTU and were elevated at low turbidities (5, 12 and 25 NTU). Expression of stress-related genes indicated significant responses for gst, hsp70 and glut2 in high turbidities (250 NTU), and principal component analysis on all measured genes revealed a clustering of 25, 35, 50 and 80 NTU separating the medium-turbidity treatments from low- and high-turbidity treatments. Taken together, these data demonstrate that turbidity levels that are either too low or too high affect

  15. Assessments at multiple levels of biological organization allow for an integrative determination of physiological tolerances to turbidity in an endangered fish species.

    PubMed

    Hasenbein, Matthias; Fangue, Nann A; Geist, Juergen; Komoroske, Lisa M; Truong, Jennifer; McPherson, Rina; Connon, Richard E

    2016-01-01

    Turbidity can influence trophic levels by altering species composition and can potentially affect fish feeding strategies and predator-prey interactions. The estuarine turbidity maximum, described as an area of increased suspended particles, phytoplankton and zooplankton, generally represents a zone with higher turbidity and enhanced food sources important for successful feeding and growth in many fish species. The delta smelt (Hypomesus transpacificus) is an endangered, pelagic fish species endemic to the San Francisco Estuary and Sacramento-San Joaquin River Delta, USA, where it is associated with turbid waters. Turbidity is known to play an important role for the completion of the species' life cycle; however, turbidity ranges in the Delta are broad, and specific requirements for this fish species are still unknown. To evaluate turbidity requirements for early life stages, late-larval delta smelt were maintained at environmentally relevant turbidity levels ranging from 5 to 250 nephelometric turbidity units (NTU) for 24 h, after which a combination of physiological endpoints (molecular biomarkers and cortisol), behavioural indices (feeding) and whole-organism measures (survival) were determined. All endpoints delivered consistent results and identified turbidities between 25 and 80 NTU as preferential. Delta smelt survival rates were highest between 12 and 80 NTU and feeding rates were highest between 25 and 80 NTU. Cortisol levels indicated minimal stress between 35 and 80 NTU and were elevated at low turbidities (5, 12 and 25 NTU). Expression of stress-related genes indicated significant responses for gst, hsp70 and glut2 in high turbidities (250 NTU), and principal component analysis on all measured genes revealed a clustering of 25, 35, 50 and 80 NTU separating the medium-turbidity treatments from low- and high-turbidity treatments. Taken together, these data demonstrate that turbidity levels that are either too low or too high affect delta

  16. Time-resolved diffusion tomographic 2D and 3D imaging in highly scattering turbid media

    NASA Technical Reports Server (NTRS)

    Alfano, Robert R. (Inventor); Cai, Wei (Inventor); Liu, Feng (Inventor); Lax, Melvin (Inventor); Das, Bidyut B. (Inventor)

    1999-01-01

    A method for imaging objects in highly scattering turbid media. According to one embodiment of the invention, the method involves using a plurality of intersecting source/detectors sets and time-resolving equipment to generate a plurality of time-resolved intensity curves for the diffusive component of light emergent from the medium. For each of the curves, the intensities at a plurality of times are then inputted into the following inverse reconstruction algorithm to form an image of the medium: ##EQU1## wherein W is a matrix relating output at source and detector positions r.sub.s and r.sub.d, at time t, to position r, .LAMBDA. is a regularization matrix, chosen for convenience to be diagonal, but selected in a way related to the ratio of the noise, to fluctuations in the absorption (or diffusion) X.sub.j that we are trying to determine: .LAMBDA..sub.ij =.lambda..sub.j .delta..sub.ij with .lambda..sub.j =/<.DELTA.Xj.DELTA.Xj> Y is the data collected at the detectors, and X.sup.k is the kth iterate toward the desired absoption information. An algorithm, which combines a two dimensional (2D) matrix inversion with a one-dimensional (1D) Fourier transform inversion is used to obtain images of three dimensional hidden objects in turbid scattering media.

  17. Time-resolved diffusion tomographic 2D and 3D imaging in highly scattering turbid media

    NASA Technical Reports Server (NTRS)

    Alfano, Robert R. (Inventor); Cai, Wei (Inventor); Gayen, Swapan K. (Inventor)

    2000-01-01

    A method for imaging objects in highly scattering turbid media. According to one embodiment of the invention, the method involves using a plurality of intersecting source/detectors sets and time-resolving equipment to generate a plurality of time-resolved intensity curves for the diffusive component of light emergent from the medium. For each of the curves, the intensities at a plurality of times are then inputted into the following inverse reconstruction algorithm to form an image of the medium: wherein W is a matrix relating output at source and detector positions r.sub.s and r.sub.d, at time t, to position r, .LAMBDA. is a regularization matrix, chosen for convenience to be diagonal, but selected in a way related to the ratio of the noise, to fluctuations in the absorption (or diffusion) X.sub.j that we are trying to determine: .LAMBDA..sub.ij =.lambda..sub.j .delta..sub.ij with .lambda..sub.j =/<.DELTA.Xj.DELTA.Xj> Y is the data collected at the detectors, and X.sup.k is the kth iterate toward the desired absorption information. An algorithm, which combines a two dimensional (2D) matrix inversion with a one-dimensional (1D) Fourier transform inversion is used to obtain images of three dimensional hidden objects in turbid scattering media.

  18. Forty-five degree backscattering-mode nonlinear absorption imaging in turbid media

    NASA Astrophysics Data System (ADS)

    Cui, Liping; Knox, Wayne H.

    2010-03-01

    Two-color nonlinear absorption imaging has been previously demonstrated with endogenous contrast of hemoglobin and melanin in turbid media using transmission-mode detection and a dual-laser technology approach. For clinical applications, it would be generally preferable to use backscattering mode detection and a simpler single-laser technology. We demonstrate that imaging in backscattering mode in turbid media using nonlinear absorption can be obtained with as little as 1-mW average power per beam with a single laser source. Images have been achieved with a detector receiving backscattered light at a 45-deg angle relative to the incoming beams' direction. We obtain images of capillary tube phantoms with resolution as high as 20 μm and penetration depth up to 0.9 mm for a 300-μm tube at SNR ~1 in calibrated scattering solutions. Simulation results of the backscattering and detection process using nonimaging optics are demonstrated. A Monte Carlo-based method shows that the nonlinear signal drops exponentially as the depth increases, which agrees well with our experimental results. Simulation also shows that with our current detection method, only 2% of the signal is typically collected with a 5-mm-radius detector.

  19. Turbid media optical properties derived from the characteristics of propagating laser radiation beams

    NASA Astrophysics Data System (ADS)

    Gurdev, Ljuan; Dreischuh, Tanja; Vankov, Orlin; Bliznakova, Irina; Avramov, Lachezar; Stoyanov, Dimitar

    2014-06-01

    The possibility is studied to develop a straightforward analytical approach to the determination of the optical properties of liquid turbid media having forward-peaked scattering indicatrices. The approach is based on investigating the in-depth behavior of the radius and the axial intensity of a laser radiation beam propagating through the turbid medium. Based on the small-angle approximation, the detected forward-propagating light power spatial distribution, at relatively small or large optical depths along the beam axis, is obtained asymptotically in analytical form allowing one to derive relatively simple expressions of the extinction, reduced-scattering and absorption coefficients and the anisotropy factor of the medium through the characteristics of the propagating light beam. Preliminary experiments have also been performed, using Intralipid dilutions of different relatively low concentrations and measuring the cross-sectional radial distribution of the detected light power at different depths along the beam axis. The corresponding on-axis detected light power profiles have been measured independently as well. The experimental results are consistent with the analytical expressions obtained that allow one to estimate the optical coefficients and the anisotropy factor of the investigated media on the basis of the measured beam characteristics. The values obtained are near those predicted by other researchers.

  20. Dynamic analysis of coagulation of low turbidity water sources using Al- and Fe-based coagulants.

    PubMed

    Ebie, K; Kawaguchi, T; Yamaguchi, D

    2006-01-01

    The direct filtration system is widely used in the treatment of source waters with low and stable turbidity. We have previously indicated the importance of optimizing agitation strength GR and time TR in rapid mixing tanks in order to decrease filter head loss and treated water turbidity in direct filtration. In the present study, we employ a batch-type coagulation experimental apparatus that incorporates a high-sensitivity particle counter, where the particulate concentrations are measured continuously after injection of coagulant, in order to clarify the fundamental coagulation and microfloc formation dynamics. Specifically, it is shown that, after injection of the coagulant, coagulation and microfloc formation occur through distinct periods: an agglomeration preparation period, followed by an agglomeration progression period, and then finally an agglomeration stabilization period, and that optimization of the GR value is the most important consideration, although both the coagulant concentration and GR influence the time at which agglomeration begins in the preparatory period, the time at which agglomeration stabilizes after the progression period, and the concentration of initial particles with diameters of 1-3 microm at completion of agglomeration.

  1. Enhancement of transmission of laser and other radiation by soft turbid physical and biological media

    NASA Astrophysics Data System (ADS)

    Askar'yan, G. A.

    1982-07-01

    An analysis is made and experimental results are reported of studies of the transmission of laser and other radiation by turbid physical and biological media, such as layers of a scattering medium or human tissue of thickness much greater than the characteristic attenuation length. It is reported that the transmission increases strongly as a result of depression and piercing of soft scattering media. A local pressure applied to a biological tissue produces a transmission enhancement considerably greater than compression of a layer of a physically turbid medium: this is due to the displacement of blood and of muscle out of the compressed region. A reduction in the scattering and absorption is expected to occur also in the case of rf and ionizing radiations, such as charged particles, x rays, gamma rays, etc. It is pointed out that this could be useful in deep irradiation carried out with the aim of inhibiting internal morbid processes (for example, in the spinal cord) and in treatment of neuroinfectious diseases (amyotrophic lateral sclerosis, multiple sclerosis, poliomyelitis, etc.), as well as in oncological conditions, ulcers, etc.

  2. Turbidity Sensor for Bacterial Growth Measurements in Spaceflight and Simulated Micro-gravity

    NASA Astrophysics Data System (ADS)

    van Benthem, Roel; de Grave, Wubbo

    2009-11-01

    For the BIOFILTER flight experiment a set of turbidity sensors was developed for the measurement of the growth rate of the bacteria Xanthobacter autrophicus GJ10 in a fluid medium. During the flight experiment on FOTON M2 in 2005, bacterial growth was measured revealing growth rates between 0.046-0.077 h - 1 in microgravity, i.e. approximately 1.5-2.5 times slower than routinely measured under optimal laboratory conditions on earth. To increase confidence in the equipment and for comparison of the results, a ground-reference experiment was carried out in 2006, using BIOFILTER hardware mounted on a random positioning machine (RPM). The RPM performed random rotations at 0.5°/min (for settling compensation) and 90°/min (for simulated microgravity) while the environment was controlled, accurately repeating the BIOFILTER flight temperature conditions. Despite the rotations of the RPM, a normal growth rate of 0.115 h - 1 was confirmed in both cases. The operation of the turbidity sensor was verified. Biological interpretation of the measurements is however compromised due to poor mixing and other unknown physical and biological phenomena that need to be addressed for further space experiments using these kinds of systems.

  3. Turbidity current flow over an erodible obstacle and phases of sediment wave generation

    NASA Astrophysics Data System (ADS)

    Strauss, Moshe; Glinsky, Michael E.

    2012-06-01

    We study the flow of particle-laden turbidity currents down a slope and over an obstacle. A high-resolution 2-D computer simulation model is used, based on the Navier-Stokes equations. It includes poly-disperse particle grain sizes in the current and substrate. Particular attention is paid to the erosion and deposition of the substrate particles, including application of an active layer model. Multiple flows are modeled from a lock release that can show the development of sediment waves (SW). These are stream-wise waves that are triggered by the increasing slope on the downstream side of the obstacle. The initial obstacle is completely erased by the resuspension after a few flows leading to self consistent and self generated SW that are weakly dependant on the initial obstacle. The growth of these waves is directly related to the turbidity current being self sustaining, that is, the net erosion is more than the net deposition. Four system parameters are found to influence the SW growth: (1) slope, (2) current lock height, (3) grain lock concentration, and (4) particle diameters. Three phases are discovered for the system: (1) "no SW," (2) "SW buildup," and (3) "SW growth". The second phase consists of a soliton-like SW structure with a preserved shape. The phase diagram of the system is defined by isolating regions divided by critical slope angles as functions of current lock height, grain lock concentration, and particle diameters.

  4. Mechanisms of sediment flux and turbidity maintenance in the Delaware Estuary

    NASA Astrophysics Data System (ADS)

    Sommerfield, Christopher K.; Wong, Kuo-Chuin

    2011-01-01

    An observational study was conducted to identify mechanisms of suspended sediment flux and turbidity maintenance in the Delaware River estuary. From March through October 2005, instrumented moorings were deployed to obtain continuous measurements of currents and suspended sediment concentration at sites along the estuarine channel and on flanking subtidal flats. Data time series were analyzed to determine the relative influence of nontidal advection and tidal pumping on residual fluxes of sediment. Results indicate that the estuarine channel is a strongly advective transport environment with residual sediment fluxes driven mostly by gravitational circulation. Tidal pumping is a contributing process of residual sediment flux in the channel near the estuarine null point and turbidity maximum, though the magnitude and direction of pumping vary with river flow and resident sediment inventory in the upper estuary. Sediment pumping in the channel is driven by tidal asymmetries in velocity and particle settling and perhaps by tidal variations in internal mixing in the stratified lower estuary. In contrast to the estuarine channel, residual sediment fluxes over the subtidal flats are weak and dominated by tidal pumping. Landward advective fluxes of sediment in bottom waters of the lower estuarine channel are strongest during neap tides; during large spring tides sediment is mixed high in the water column and the advective flux reverses to seaward under the residual surface outflow. Despite these transient seaward fluxes, the estuary has an enormous capacity to buffer extreme freshwater discharges and suppress export of suspended sediment to Delaware Bay.

  5. 27 years of benthic and coral community dynamics on turbid, highly urbanised reefs off Singapore

    PubMed Central

    Guest, J. R.; Tun, K.; Low, J.; Vergés, A.; Marzinelli, E. M.; Campbell, A. H.; Bauman, A. G.; Feary, D. A.; Chou, L. M.; Steinberg, P. D.

    2016-01-01

    Coral cover on reefs is declining globally due to coastal development, overfishing and climate change. Reefs isolated from direct human influence can recover from natural acute disturbances, but little is known about long term recovery of reefs experiencing chronic human disturbances. Here we investigate responses to acute bleaching disturbances on turbid reefs off Singapore, at two depths over a period of 27 years. Coral cover declined and there were marked changes in coral and benthic community structure during the first decade of monitoring at both depths. At shallower reef crest sites (3–4 m), benthic community structure recovered towards pre-disturbance states within a decade. In contrast, there was a net decline in coral cover and continuing shifts in community structure at deeper reef slope sites (6–7 m). There was no evidence of phase shifts to macroalgal dominance but coral habitats at deeper sites were replaced by unstable substrata such as fine sediments and rubble. The persistence of coral dominance at chronically disturbed shallow sites is likely due to an abundance of coral taxa which are tolerant to environmental stress. In addition, high turbidity may interact antagonistically with other disturbances to reduce the impact of thermal stress and limit macroalgal growth rates. PMID:27824083

  6. State-of-the art of acousto-optic sensing and imaging of turbid media.

    PubMed

    Resink, Steffen G; Boccara, Albert C; Steenbergen, Wiendelt

    2012-04-01

    Acousto-optic (AO) is an emerging hybrid technique for measuring optical contrast in turbid media using coherent light and ultrasound (US). A turbid object is illuminated with a coherent light source leading to speckle formation in the remitted light. With the use of US, a small volume is selected,which is commonly referred to as the "tagging" volume. This volume acts as a source of modulated light, where modulation might involve phase and intensity change. The tagging volume is created by focusing ultrasound for good lateral resolution; the axial resolution is accomplished by making either the US frequency, amplitude, or phase time-dependent. Typical resolutions are in the order of 1 mm. We will concentrate on the progress in the field since 2003. Different schemes will be discussed to detect the modulated photons based on speckle detection, heterodyne detection, photorefractive crystal (PRC) assisted detection, and spectral hole burning (SHB) as well as Fabry-Perot interferometers. The SHB and Fabry-Perot interferometer techniques are insensitive to speckle decorrelation and therefore suitable for in vivo imaging. However, heterodyne and PRC methods also have potential for in vivo measurements. Besides measuring optical properties such as scattering and absorption, AO can be applied in fluorescence and elastography applications.

  7. Optical imaging through turbid media with a degenerate four wave mixing correlation time gate

    SciTech Connect

    Sappey, A.D. )

    1994-12-20

    A novel method for detection of ballistic light and rejection of unwanted diffusive light to image structures inside highly scattering media is demonstrated. Degenerate four wave mixing (DFWM) of a doubled YAG laser in Rhodamine 6G is used to provide an ultrafast correlation time gate to discriminate against light that has undergone multiple scattering and therefore lost memory of the structures inside the scattering medium. We present preliminary results that determine the nature of the DFWM grating, confirm the coherence time of the laser, prove the phase-conjugate nature of the signal beam, and determine the dependence of the signal (reflectivity) on dye concentration and laser intensity. Finally, we have obtained images of a test cross-hair pattern through highly turbid suspensions of whole milk in water that are opaque to the naked eye. These imaging experiments demonstrate the utility of DFWM for imaging through turbid media. Based on our results, the use of DFWM as an ultrafast time gate for the detection of ballistic light in optical mammography appears to hold great promise for improving the current state of the art.

  8. High resolution simulations of down-slope turbidity currents into stratified saline ambient

    NASA Astrophysics Data System (ADS)

    Ouillon, Raphael; Radhakrishnan, Senthil; Meiburg, Eckart; Sutherland, Bruce

    2016-11-01

    In this work we explore the properties of turbidity currents moving down a slope into a stratified saline ambient through highly resolved 3D Navier-Stokes simulations. Turbidity events are difficult to measure and to replicate experimentally for a wide range of parameters, but they play a key role in ocean, lake or river sediment transport. Our objectives are to improve on previous numerical studies, obtain quantitative data in a more controlled environment than current experimental set-ups, and combine results with analytical arguments to build physics-based scaling laws. We validate our results and propose a simple scaling law to predict the velocity of the front down a slope for any stratification. We also compute a time and space dependent entrainment of ambient fluid and highlight its strong variability. We then introduce a predictable scaling law for the intrusion depth that does not depend on an averaged entrainment and uses it as a verification tool instead. Finally, we show that the ratio of Stokes losses in the local flow around individual particles to dissipative losses of the large scale flow determines the ability of the flow to convert potential energy into kinetic energy. For different parameters, either mechanism can dominate the dynamics of the flow.

  9. Multiple scattering of polarized light in turbid birefringent media: a Monte Carlo simulation.

    PubMed

    Otsuki, Soichi

    2016-07-20

    Multiple scattering of polarized light in a birefringent turbid plane medium was studied using a Monte Carlo simulation. The reduced effective scattering Mueller matrix obtained in the simulation was factorized in two dimensions using the Lu-Chipman decomposition, yielding polarization parameters that exhibited dependences on the azimuth and the radial distance around the illumination point. We propose a double-scattering model for the propagation of polarized photons in turbid infinite plane media. When the birefringence slow axis is along the azimuth of 90° on the plane surface, the retardance becomes the largest negative along the azimuth of 0° and the largest positive along the azimuth of 90° and increases with increasing the azimuth from 0° to 90°. This azimuthal dependence may result from the overlap of the contributions from the light propagations vertical to, and lateral along, the plane surface. Thus, the dependences on the azimuth and the radial distance of the polarization parameters, such as the retardance, its orientation, optical rotation, and the depolarization coefficients, are correctly predicted.

  10. Backscattering of linearly polarized light from turbid tissue-like scattering medium with rough surface

    NASA Astrophysics Data System (ADS)

    Doronin, Alexander; Tchvialeva, Lioudmila; Markhvida, Igor; Lee, Tim K.; Meglinski, Igor

    2016-07-01

    In the framework of further development of a unified computational tool for the needs of biomedical optics, we introduce an electric field Monte Carlo (MC) model for simulation of backscattering of coherent linearly polarized light from a turbid tissue-like scattering medium with a rough surface. We consider the laser speckle patterns formation and the role of surface roughness in the depolarization of linearly polarized light backscattered from the medium. The mutual phase shifts due to the photons' pathlength difference within the medium and due to reflection/refraction on the rough surface of the medium are taken into account. The validation of the model includes the creation of the phantoms of various roughness and optical properties, measurements of co- and cross-polarized components of the backscattered/reflected light, its analysis and extensive computer modeling accelerated by parallel computing on the NVIDIA graphics processing units using compute unified device architecture (CUDA). The analysis of the spatial intensity distribution is based on second-order statistics that shows a strong correlation with the surface roughness, both with the results of modeling and experiment. The results of modeling show a good agreement with the results of experimental measurements on phantoms mimicking human skin. The developed MC approach can be used for the direct simulation of light scattered by the turbid scattering medium with various roughness of the surface.

  11. Time-resolved subtraction method for measuring optical properties of turbid media.

    PubMed

    Milej, Daniel; Abdalmalak, Androu; Janusek, Dariusz; Diop, Mamadou; Liebert, Adam; St Lawrence, Keith

    2016-03-01

    Near-infrared spectroscopy is a noninvasive optical method used primarily to monitor tissue oxygenation due to the absorption properties of hemoglobin. Accurate estimation of hemoglobin concentrations and other light absorbers requires techniques that can separate the effect of absorption from the much greater effect of light scattering. One of the most advanced methods is time-resolved near-infrared spectroscopy (TR-NIRS), which measures the absorption and scattering coefficients of a turbid medium by modeling the recorded distribution time of flight of photons. A challenge with TR-NIRS is that it requires accurate characterization of the dispersion caused by the system. In this study, we present a method for circumventing this problem by applying statistical moment analysis to two time-of-flight distributions measured at separated source-detector distances. Simulations based on analytical models and Monte Carlo code, and tissue-mimicking phantoms, were used to demonstrate its accuracy for source-detector distances typically used in neuroimaging applications. The simplicity of the approach is well suited to real-time applications requiring accurate quantification of the optical properties of a turbid medium.

  12. Propagation and scattering of vector light beam in turbid scattering medium

    NASA Astrophysics Data System (ADS)

    Doronin, Alexander; Milione, Giovanni; Meglinski, Igor; Alfano, Robert R.

    2014-03-01

    Due to its high sensitivity to subtle alterations in medium morphology the vector light beams have recently gained much attention in the area of photonics. This leads to development of a new non-invasive optical technique for tissue diagnostics. Conceptual design of the particular experimental systems requires careful selection of various technical parameters, including beam structure, polarization, coherence, wavelength of incident optical radiation, as well as an estimation of how the spatial and temporal structural alterations in biological tissues can be distinguished by variations of these parameters. Therefore, an accurate realistic description of vector light beams propagation within tissue-like media is required. To simulate and mimic the propagation of vector light beams within the turbid scattering media the stochastic Monte Carlo (MC) technique has been used. In current report we present the developed MC model and the results of simulation of different vector light beams propagation in turbid tissue-like scattering media. The developed MC model takes into account the coherent properties of light, the influence of reflection and refraction at the medium boundary, helicity flip of vortexes and their mutual interference. Finally, similar to the concept of higher order Poincaŕe sphere (HOPS), to link the spatial distribution of the intensity of the backscattered vector light beam and its state of polarization on the medium surface we introduced the color-coded HOPS.

  13. 27 years of benthic and coral community dynamics on turbid, highly urbanised reefs off Singapore.

    PubMed

    Guest, J R; Tun, K; Low, J; Vergés, A; Marzinelli, E M; Campbell, A H; Bauman, A G; Feary, D A; Chou, L M; Steinberg, P D

    2016-11-08

    Coral cover on reefs is declining globally due to coastal development, overfishing and climate change. Reefs isolated from direct human influence can recover from natural acute disturbances, but little is known about long term recovery of reefs experiencing chronic human disturbances. Here we investigate responses to acute bleaching disturbances on turbid reefs off Singapore, at two depths over a period of 27 years. Coral cover declined and there were marked changes in coral and benthic community structure during the first decade of monitoring at both depths. At shallower reef crest sites (3-4 m), benthic community structure recovered towards pre-disturbance states within a decade. In contrast, there was a net decline in coral cover and continuing shifts in community structure at deeper reef slope sites (6-7 m). There was no evidence of phase shifts to macroalgal dominance but coral habitats at deeper sites were replaced by unstable substrata such as fine sediments and rubble. The persistence of coral dominance at chronically disturbed shallow sites is likely due to an abundance of coral taxa which are tolerant to environmental stress. In addition, high turbidity may interact antagonistically with other disturbances to reduce the impact of thermal stress and limit macroalgal growth rates.

  14. Study on 3-D simulation of flow and turbidity in an oxbow lake in tidal compartment

    NASA Astrophysics Data System (ADS)

    Yokoyama, H.; Momonoe, H.; Hamamoto, S.

    2010-12-01

    We aimed to make flow and turbidity simulation model for an oxbow lake in tidal compartment. The oxbow has two bottle-necks and inflow river from urban district. Bed topography of the oxbow is former meandering channel of large-basin river. Therefore characteristic of flow and water quality is complex. First, field observation was conducted to clarify the characteristics of flow and water quality in the oxbow. From observation results, flow and resuspension phenomena in the oxbow were affected by wind and tide, and the balance of the two factors changed longitudinally. Next, we built 3-D simulation model of flow which took account of the field observation results. In order to investigate effective water quality improvement, we set some test cases: condition of wind, inflow river were changed. From the simulation results, tide was the most important factor, however at the upper part of the oxbow, where the tidal power seemed to be weaker, flow and turbidity were clearly affected by the wind.

  15. Variations of Estuarine Turbid Plumes and Mudflats in Response to Human Activities and Climate Change

    NASA Astrophysics Data System (ADS)

    Doxaran, David; Salama, Suhyb; Yu, Xiaolong; Shen, Fang; Zhou, Yunxuan

    2014-11-01

    Estuarine and coastal waters are referred to as Case 2 waters and much more optically complex because the optical properties of chlorophyll-a (Chla), non-algae particles (NAP), and colored dissolved organic matter (CDOM) and their concentrations are subjected to potentially large and independent variations. As for the Yangtze estuarine and coastal water, its relatively higher concentration of Suspended Particulate Matter (SPM) among world's estuarine and coastal waters provides a reference test site for studying ocean colour algorithms and remote sensing applications in wide-range sediment concentration water and extremely turbid water. Regarding the Dragon 3 project, algorithms for atmosphere correction were improved (Salama and Shen, 2010; Shen and Verhoef, 2010); several novel models to retrieve bio-optical properties, such as concentrations of SPM, Chla and inherent optical properties(IOPs), were also developed for medium and extremely turbid waters, that is the SERT model (Shen et al., 2010), the SCI algorithm (Shen et al., 2010) and the 2SeaColor model (Salama and Verhoef, 2014). Data acquired from both in-situmeasurements and satellite were used for models development and improvement and the results are shown as follows. In general, four aspects of the work have been involved in by the Chinese and European partners by far.

  16. Single snapshot multiple frequency modulated imaging of subsurface optical properties of turbid media with structured light

    NASA Astrophysics Data System (ADS)

    Xu, M.; Cao, Zili; Lin, Weihao; Chen, Xinlin; Zheng, Longfei; Zeng, Bixin

    2016-12-01

    We report a novel demodulation method that enables single snapshot wide field imaging of optical properties of turbid media in the Spatial Frequency Domain (SFD). This Single Snapshot Multiple frequency Demodulation (SSMD) method makes use of the orthogonality of harmonic functions to extract the modulation transfer function (MTF) at multiple modulation frequencies simultaneously from a single structured-illuminated image at once. The orientation, frequency, and amplitude of each modulation can be set arbitrarily subject to the limitation of the implementation device. We first validate and compare SSMD to the existing demodulation methods by numerical simulations. The performance of SSMD is then demonstrated with experiments on both tissue mimicking phantoms and in vivo for recovering optical properties by comparing to the standard three-phase demodulation approach. The results show that SSMD increases significantly the data acquisition speed and reduces motion artefacts. SSMD exhibits excellent noise suppression in imaging as well at the rate proportional to the square root of the number of pixels contained in its kernel. SSMD is ideal in the implementation of a real-time spatial frequency domain imaging platform and will open up SFDI for vast applications in imaging and monitoring dynamic turbid medium and processes.

  17. Radiative transport produced by oblique illumination of turbid media with collimated beams.

    PubMed

    Gardner, Adam R; Kim, Arnold D; Venugopalan, Vasan

    2013-06-01

    We examine the general problem of light transport initiated by oblique illumination of a turbid medium with a collimated beam. This situation has direct relevance to the analysis of cloudy atmospheres, terrestrial surfaces, soft condensed matter, and biological tissues. We introduce a solution approach to the equation of radiative transfer that governs this problem, and develop a comprehensive spherical harmonics expansion method utilizing Fourier decomposition (SHEF(N)). The SHEF(N) approach enables the solution of problems lacking azimuthal symmetry and provides both the spatial and directional dependence of the radiance. We also introduce the method of sequential-order smoothing that enables the calculation of accurate solutions from the results of two sequential low-order approximations. We apply the SHEF(N) approach to determine the spatial and angular dependence of both internal and boundary radiances from strongly and weakly scattering turbid media. These solutions are validated using more costly Monte Carlo simulations and reveal important insights regarding the evolution of the radiant field generated by oblique collimated beams spanning ballistic and diffusely scattering regimes.

  18. Turbidity in the fluvial Gironde Estuary (southwest France) based on 10-year continuous monitoring: sensitivity to hydrological conditions

    NASA Astrophysics Data System (ADS)

    Jalón-Rojas, I.; Schmidt, S.; Sottolichio, A.

    2015-06-01

    Climate change and human activities impact the volume and timing of freshwater input to estuaries. These modifications in fluvial discharges are expected to influence estuarine suspended sediment dynamics, and in particular the turbidity maximum zone (TMZ). Located in southwest France, the Gironde fluvial-estuarine system has an ideal context to address this issue. It is characterized by a very pronounced TMZ, a decrease in mean annual runoff in the last decade, and it is quite unique in having a long-term and high-frequency monitoring of turbidity. The effect of tide and river flow on turbidity in the fluvial estuary is detailed, focusing on dynamics related to changes in hydrological conditions (river floods, periods of low discharge, interannual changes). Turbidity shows hysteresis loops at different timescales: during river floods and over the transitional period between the installation and expulsion of the TMZ. These hysteresis patterns, that reveal the origin of sediment, locally resuspended or transported from the watershed, may be a tool to evaluate the presence of remained mud. Statistics on turbidity data bound the range of river flow that promotes the upstream migration of TMZ in the fluvial stations. Whereas the duration of the low discharge period mainly determines the TMZ persistence, the freshwater volume during high discharge periods explains the TMZ concentration at the following dry period. The evolution of these two hydrological indicators of TMZ persistence and turbidity level since 1960 confirms the effect of discharge decrease on the intensification of the TMZ in tidal rivers; both provide a tool to evaluate future scenarios.

  19. Large-scale climate control on the occurrence of turbid events on interannual scales in a karstified, heavily exploited karst system in northwestern France

    NASA Astrophysics Data System (ADS)

    Massei, N.; Laignel, B.; Dupont, J. P.

    2015-12-01

    High-amplitude turbid episodes at water supplies can cause significant sanitary issues to populations. Owing to their hydrogeologic specificity, karst ground waters are particularly sensitive to such phenomena, involving either fast infiltration of turbid surface water or resuspension of intra-karstic sediments during flood events. In some regions, such as Upper Normandy (France), soil erosion and karst features in the chalk aquifer are at the origin of major turbid events which may result in interrupted water supply to the local populations. Thanks to a long daily turbidity time series corresponding to measurements at one major karst spring since the mid-80's, we could investigate the large-scale atmospheric circulation control on below- or above-average turbidity periods. The turbidity time-series actually display periods on pluriannual duration during which daily turbid events are more frequent and have higher amplitudes, which can not be seen on daily precipitation records. Comparison was made between annual precipitation amounts, chalk aquifer water table variations and turbidity throughout this approximately 25-year period, which showed interannual recharge periods associated to above-normal turbid conditions. We then studied the linkages between such variations and large-scale atmospheric circulation using a NOAA sea level pressure reanalysis product. A wavelet multiresolution analysis of all hydrological and climatic signals revealed common aperiodic oscillations on interannual scales and allowed identification of the large-scale, interannual-scale atmospheric pattern that was responsible for those above-normal turbid periods; this atmospheric pattern was not necessarily similar to that responsible to any individual short-term turbid event.

  20. Ecology of pathogenic and non-pathogenic Vibrio parahaemolyticus on the French Atlantic coast. Effects of temperature, salinity, turbidity and chlorophyll a.

    PubMed

    Julie, Deter; Solen, Lozach; Antoine, Véron; Jaufrey, Chollet; Annick, Derrien; Dominique, Hervio-Heath

    2010-04-01

    Vibrio parahaemolyticus is one of the principal bacterial causes for seafood-borne gastroenteritis in the world. In the present study, three sites located on the French Atlantic coast were monitored monthly for environmental parameters over 1 year. The presence of total and pathogenic V. parahaemolyticus in sediment, water and mussel samples was detected following enrichment by culture and real-time PCR (toxR gene, tdh, trh1 and trh2 virulence genes). Using generalized linear models, we showed that the presence of V. parahaemolyticus in water could be explained by a combination of mean temperature over the 7 days before the day of sampling (P < 0.001) and turbidity (P = 0.058). In mussels, an effect of chlorophyll a (P = 0.005) was detected when an effect of the mean salinity over the 7 days before sampling was significant for the sediment (P < 0.001). We did not detect any significant effect of phytoplanktonic blooms or of the number of culturable bacteria on V. parahaemolyticus presence. No sample was revealed positive for tdh. The presence of trh1 and trh2 was positively influenced by the mean temperature during the 2 days before the day of sampling (P < 0.001 and P = 0.032). The importance of these ecological parameters is discussed in relation to the biology of V. parahaemolyticus.

  1. Statistical properties and time-frequency analysis of temperature, salinity and turbidity measured by the MAREL Carnot station in the coastal waters of Boulogne-sur-Mer (France)

    NASA Astrophysics Data System (ADS)

    Kbaier Ben Ismail, Dhouha; Lazure, Pascal; Puillat, Ingrid

    2016-10-01

    In marine sciences, many fields display high variability over a large range of spatial and temporal scales, from seconds to thousands of years. The longer recorded time series, with an increasing sampling frequency, in this field are often nonlinear, nonstationary, multiscale and noisy. Their analysis faces new challenges and thus requires the implementation of adequate and specific methods. The objective of this paper is to highlight time series analysis methods already applied in econometrics, signal processing, health, etc. to the environmental marine domain, assess advantages and inconvenients and compare classical techniques with more recent ones. Temperature, turbidity and salinity are important quantities for ecosystem studies. The authors here consider the fluctuations of sea level, salinity, turbidity and temperature recorded from the MAREL Carnot system of Boulogne-sur-Mer (France), which is a moored buoy equipped with physico-chemical measuring devices, working in continuous and autonomous conditions. In order to perform adequate statistical and spectral analyses, it is necessary to know the nature of the considered time series. For this purpose, the stationarity of the series and the occurrence of unit-root are addressed with the Augmented-Dickey Fuller tests. As an example, the harmonic analysis is not relevant for temperature, turbidity and salinity due to the nonstationary condition, except for the nearly stationary sea level datasets. In order to consider the dominant frequencies associated to the dynamics, the large number of data provided by the sensors should enable the estimation of Fourier spectral analysis. Different power spectra show a complex variability and reveal an influence of environmental factors such as tides. However, the previous classical spectral analysis, namely the Blackman-Tukey method, requires not only linear and stationary data but also evenly-spaced data. Interpolating the time series introduces numerous artifacts to the

  2. Atmospheric turbidity of urban and desert areas of the Nile Basin in the aftermath of Mt. Pinatubo's eruption

    NASA Astrophysics Data System (ADS)

    El-Wakil, S. A.; El-Metwally, M.; Gueymard, C.

    The Linke TL, Ångström β and Unsworth-Monteith δa turbidity parameters are investigated for two sites in Egypt: Cairo, a densely populated urban area, and Aswan, an arid unpolluted area. These three turbidity parameters are calculated from broadband pyrheliometric measurements recorded hourly over the period 1992-96. Monthly averages of TL, β and δa show relatively flat and identical seasonal variations with a marked main maxima during spring at both sites, due to Khamsin depressions coming from the Great Sahara. A secondary maximum is observed at Aswan in summer, due to dust haze which prevails during that season, and at Cairo in autumn, due to the northern extension of the Sudan monsoon trough, which is accompanied by small scale depressions with dust particles. Annual mean values of TL, β and δa (5.59, 0.250 and 0.372, respectively) at Cairo are larger than at Aswan (3.89, 0.139 and 0.213, respectively). In the same way, the seasonal mean values of TL, β and δa at Cairo are larger than at Aswan. More generally, the monthly and yearly average turbidity values are significantly larger in Cairo than in Aswan for the whole period 1992-96, which is attributable in part to the urbanization/industrialization effect of Cairo. An estimate of the corresponding overburden is obtained by comparison between the present data and older TL data from 1922-27. It is also shown that turbidity over both sites is largest during 1992, just after the eruption of Mount Pinatubo in 1991. The dependence of β on some meteorological parameters such as wind speed and direction, precipitable water, relative humidity, temperature and visibility, is also analyzed. This reveals in particular that visibility is not a good predictor of turbidity at either site. Conversely, the wind direction and speed have a definite effect on turbidity, and consequently, largest turbidities occur when the wind carries aerosols from the main industrial particle source areas around Cairo. For any season

  3. Satellite-based estimation of chlorophyll-a concentration in turbid productive waters

    NASA Astrophysics Data System (ADS)

    Moses, Wesley Jeremiah

    Inland, coastal, and estuarine waters, which are often turbid and biologically productive, play a crucial role in maintaining global bio-diversity and are of immense value to aquatic life as well as human-beings. Concentration of chlorophyll-a (chl-a) is a key indicator of the trophic status of these waters, which should be regularly monitored to ensure that their ecological balance is not disturbed. Remote sensing is a powerful tool for this. Due to the optical complexity of turbid productive waters, standard algorithms that use blue and green reflectances are unreliable for estimating chl- a concentration. Algorithms based on red and near-infrared (NIR) reflectances are preferable. Three-band and two-band NIR-red models based on the spectral channels of MODIS and MERIS satellites have been tested for numerous datasets collected with field spectrometers from inland, coastal, and estuarine waters. The NIR-red models, especially the two-band model with MERIS wavebands, gave consistently highly accurate estimates of chl- a concentration in waters from different geographic locations with widely varying biophysical characteristics, without the need to re-parameterize the algorithms for each different water body. The MODIS NIR-red model can be used to estimate moderate-to-high chl-a concentrations. The NIR-red models were applied to airborne AISA data acquired over several lakes in Nebraska on different days with non-uniform atmospheric conditions. Without atmospheric correction, the NIR-red models showed a close correlation with chl-a concentration for each image. With an effective relative correction for the non-uniform atmospheric effects on the multi-temporal images, the NIR-red models were shown to have a close correlation with chl- a concentration, with uniform slope and offset, for the whole dataset. The models were also applied to MODIS and MERIS images. Reliable results were obtained from the MERIS NIR-red models. Calibrated MERIS NIR-red algorithms were

  4. Turbidity Current Transport using DEM and FEM: a Hybrid Lagrangian-Eulerian Approach

    NASA Astrophysics Data System (ADS)

    Alves, J. L.; Guevara, N. O., Jr.; Silva, C. E.; Alves, F. T.; Gazoni, L. C.; Coutinho, A.; Camata, J.; Elias, R. N.; Paraizo, P.

    2013-05-01

    In this work we describe a contribution to the study of turbidity transport in scales smaller than TFM (two-fluid models), The intent of the work, part of a large scale simulation project, is to assess local, small scale parameters and their upscaling. The hybrid model is based on a Lagrangian-Eulerian approach under a class of the so called Unresolved Discrete Particle Method (UDPM). In this approach, a Lagrangian description is used for the particle system employing the Discrete Element Method (DEM) while a fixed Eulerian mesh is used for the fluid phase modeled by finite element method (FEM), Fluid motion is governed by Navier-Stokes equations which are solved by an appropriate FEM implementation. Closure equation are used to compute drag and lift forces over the particles in the DEM framework. Volume averaged momentum sink terms are included in the fluid equations. The resulting coupled DEM-FEM model is integrated in time with a subcycling scheme. The aforementioned scheme was applied in the simulation of a sedimentation basin as depicted in figures 1 and 2 to investigate flow and deposition features of the suspension in a finer scale. For this purpose a submodel of the basin was generated. Mapping variables back and forth the Eulerian (finite element) model and the Lagrangian (discrete element) model were performed during the subcycled integration of the hybrid model. References: [1] Hoomans, B.P.B., Kuipers, J.A.M., Swaaij, van W.P.M," Granular dynamics Simulation of segregation phenomena in bubbling gas-fluidised beds", Powder Technology, V 109, Issues 1-3, 3 April 2000, pp 41-48; [2] Cho, S.H., Choi,H.G, Yoo, J.Y.,"Direct numerical simulation of fluid flow laden with many particles", International Journal of Multiphase Flow, V 31, Issue 4, April 2005, pp 435-451;; Sedimentation basin: sectioning the turbidity plume in the Eulerian FE model for setting up the discrete particle model. ; Sedimentation Basin: section of the turbidity plume displaying the

  5. Shifting roles of heterotrophy and autotrophy in coral energetics under varying turbidity.

    PubMed

    Anthony; Fabricius

    2000-09-20

    dry weight l(-1), and four- to eight-fold lower than those of G. retiformis. Skeletal growth was sustained, but tissue mass and lipid contents declined in shaded and high-SPM treatments, and carbon loss due to shading by SPM was not compensated for by particle feeding. Thus, due to a lack of photo- and heterotrophic plasticity, periods of high turbidity resulted in energy deficiency in P. cylindrica, and high turbidity conditions appeared physiologically unsustainable for this species. This study is the first to show heterotrophic plasticity in a symbiotic coral, and to show that such plasticity can offset stress from high particle loads. It demonstrates that changes in the trophic mode of some coral species are a mechanism for sustaining a positive energy balance in turbid environments, thereby broadening their physiological niche.

  6. Biogeochemical mass balances in a turbid tropical reservoir. Field data and modelling approach

    NASA Astrophysics Data System (ADS)

    Phuong Doan, Thuy Kim; Némery, Julien; Gratiot, Nicolas; Schmid, Martin

    2014-05-01

    The turbid tropical Cointzio reservoir, located in the Trans Mexican Volcanic Belt (TMVB), behaves as a warm monomictic water body (area = 6 km2, capacity 66 Mm3, residence time ~ 1 year). It is strategic for the drinking water supply of the city of Morelia, capital of the state of Michoacán, and for downstream irrigation during the dry season. This reservoir is a perfect example of a human-impacted system since its watershed is mainly composed of degraded volcanic soils and is subjected to high erosion processes and agricultural loss. The reservoir is threatened by sediment accumulation and nutrients originating from untreated waters in the upstream watershed. The high content of very fine clay particles and the lack of water treatment plants lead to serious episodes of eutrophication (up to 70 μg chl. a L-1), high levels of turbidity (Secchi depth < 30 cm) and a long period of anoxia (from May to October). Based on intensive field measurements in 2009 (deposited sediment, benthic chamber, water vertical profiles, reservoir inflow and outflow) we determined suspended sediment (SS), carbon (C), nitrogen (N) and phosphorus (P) mass balances. Watershed SS yields were estimated at 35 t km2 y-1 of which 89-92 % were trapped in the Cointzio reservoir. As a consequence the reservoir has already lost 25 % of its initial storage capacity since its construction in 1940. Nutrient mass balances showed that 50 % and 46 % of incoming P and N were retained by sedimentation, and mainly eliminated through denitrification respectively. Removal of C by 30 % was also observed both by sedimentation and through gas emission. To complete field data analyses we examined the ability of vertical one dimensional (1DV) numerical models (Aquasim biogeochemical model coupled with k-ɛ mixing model) to reproduce the main biogeochemical cycles in the Cointzio reservoir. The model can describe all the mineralization processes both in the water column and in the sediment. The values of the

  7. Remote-Sensing Technique for Determination of the Volume Absorption Coefficient of Turbid Water

    NASA Astrophysics Data System (ADS)

    Sydor, Michael; Arnone, Robert A.; Gould, Richard W., Jr.; Terrie, Gregory E.; Ladner, Sherwin D.; Wood, Christoper G.

    1998-07-01

    We use remote-sensing reflectance from particulate R rs to determine the volume absorption coefficient a of turbid water in the 400 700-nm spectral region. The calculated and measured values of a ( ) show good agreement for 0 . 5 a 10 (m 1 ). To determine R rs from a particulate, we needed to make corrections for remote-sensing reflectance owing to surface roughness S rs . We determined the average spectral distribution of S rs from the difference in total remote-sensing reflectance measured with and without polarization. The spectral shape of S rs showed an excellent fit to theoretical formulas for glare based on Rayleigh and aerosol scattering from the atmosphere.

  8. Frequency-modulated light scattering interferometry employed for optical properties and dynamics studies of turbid media

    PubMed Central

    Mei, Liang; Somesfalean, Gabriel; Svanberg, Sune

    2014-01-01

    In the present work, fiber-based frequency-modulated light scattering interferometry (FMLSI) is developed and employed for studies of optical properties and dynamics in liquid phantoms made from Intralipid®. The fiber-based FMLSI system retrieves the optical properties by examining the intensity fluctuations through the turbid medium in a heterodyne detection scheme using a continuous-wave frequency-modulated coherent light source. A time resolution of 21 ps is obtained, and the experimental results for the diluted Intralipid phantoms show good agreement with the predicted results based on published data. The present system shows great potential for assessment of optical properties as well as dynamic studies in liquid phantoms, dairy products, and human tissues. PMID:25136504

  9. Numerical modeling of the radiative transfer in a turbid medium using the synthetic iteration.

    PubMed

    Budak, Vladimir P; Kaloshin, Gennady A; Shagalov, Oleg V; Zheltov, Victor S

    2015-07-27

    In this paper we propose the fast, but the accurate algorithm for numerical modeling of light fields in the turbid media slab. For the numerical solution of the radiative transfer equation (RTE) it is required its discretization based on the elimination of the solution anisotropic part and the replacement of the scattering integral by a finite sum. The solution regular part is determined numerically. A good choice of the method of the solution anisotropic part elimination determines the high convergence of the algorithm in the mean square metric. The method of synthetic iterations can be used to improve the convergence in the uniform metric. A significant increase in the solution accuracy with the use of synthetic iterations allows applying the two-stream approximation for the regular part determination. This approach permits to generalize the proposed method in the case of an arbitrary 3D geometry of the medium.

  10. Impacts of turbidity on corals: The relative importance of light limitation and suspended sediments.

    PubMed

    Bessell-Browne, Pia; Negri, Andrew P; Fisher, Rebecca; Clode, Peta L; Duckworth, Alan; Jones, Ross

    2017-04-15

    As part of an investigation of the effects of water quality from dredging/natural resuspension on reefs, the effects of suspended sediment concentrations (SSCs) (0, 30, 100mgL(-1)) and light (~0, 1.1, 8.6molphotonsm(-2)d(-1)) were examined alone and in combination, on the corals Acropora millepora, Montipora capricornis and Porites spp. over an extended (28d) period. No effects were observed at any sediment concentrations when applied alone. All corals in the lowest light treatments lost chlorophyll a and discoloured (bleached) after a week. Coral mortality only occurred in the two lowest light treatments and was higher when simultaneously exposed to elevated SSCs. Compared to water quality data collected during large dredging programs and natural resuspension events (and in the absence of sediment deposition as a cause-effect pathway) these data suggest the light reduction associated with turbidity poses a proportionally greater risk than effects of elevated SSCs alone.

  11. Non-contact spectroscopic determination of large blood volume fractions in turbid media

    PubMed Central

    Bremmer, Rolf H.; Kanick, Stephen C.; Laan, Nick; Amelink, Arjen; van Leeuwen, Ton G.; Aalders, Maurice C. G.

    2011-01-01

    We report on a non-contact method to quantitatively determine blood volume fractions in turbid media by reflectance spectroscopy in the VIS/NIR spectral wavelength range. This method will be used for spectral analysis of tissue with large absorption coefficients and assist in age determination of bruises and bloodstains. First, a phantom set was constructed to determine the effective photon path length as a function of μa and μs′ on phantoms with an albedo range: 0.02-0.99. Based on these measurements, an empirical model of the path length was established for phantoms with an albedo > 0.1. Next, this model was validated on whole blood mimicking phantoms, to determine the blood volume fractions ρ = 0.12-0.84 within the phantoms (r = 0.993; error < 10%). Finally, the model was proved applicable on cotton fabric phantoms. PMID:21339884

  12. Monte Carlo simulation of multiphoton fluorescence microscopic imaging through inhomogeneous tissuelike turbid media.

    PubMed

    Deng, Xiaoyuan; Gan, Xiaosong; Gu, Min

    2003-07-01

    Image resolution and signal level in fluorescence microscopy through inhomogeneous turbid media consisting of scatterers of multiple sizes under single- (1p), two- (2p), and three-photon (3p) excitation have been investigated based on a modified Monte Carlo model. The effects of the size distribution and the concentration distribution of scattering particles are explored. Simulation results reveal that the size and the concentration distribution both have an impact on image formation in media consisting of small particles and that 3p excitation has the most significant impact. In media with scatterers of a large size, both size and concentration distributions lead to a slight effect. Image formation in a mixed medium containing small and large scattering particles is more affected by the large particles.

  13. Using graphics processing units to accelerate perturbation Monte Carlo simulation in a turbid medium

    NASA Astrophysics Data System (ADS)

    Cai, Fuhong; He, Sailing

    2012-04-01

    We report a fast perturbation Monte Carlo (PMC) algorithm accelerated by graphics processing units (GPU). The two-step PMC simulation [Opt. Lett. 36, 2095 (2011)] is performed by storing the seeds instead of the photon's trajectory, and thus the requirement in computer random-access memory (RAM) becomes minimal. The two-step PMC is extremely suitable for implementation onto GPU. In a standard simulation of spatially-resolved photon migration in the turbid media, the acceleration ratio between using GPU and using conventional CPU is about 1000. Furthermore, since in the two-step PMC algorithm one records the effective seeds, which is associated to the photon that reaches a region of interest in this letter, and then re-run the MC simulation based on the recorded effective seeds, radiative transfer equation (RTE) can be solved by two-step PMC not only with an arbitrary change in the absorption coefficient, but also with large change in the scattering coefficient.

  14. Using graphics processing units to accelerate perturbation Monte Carlo simulation in a turbid medium.

    PubMed

    Cai, Fuhong; He, Sailing

    2012-04-01

    We report a fast perturbation Monte Carlo (PMC) algorithm accelerated by graphics processing units (GPU). The two-step PMC simulation [Opt. Lett. 36, 2095 (2011)] is performed by storing the seeds instead of the photon's trajectory, and thus the requirement in computer random-access memory (RAM) becomes minimal. The two-step PMC is extremely suitable for implementation onto GPU. In a standard simulation of spatially-resolved photon migration in the turbid media, the acceleration ratio between using GPU and using conventional CPU is about 1000. Furthermore, since in the two-step PMC algorithm one records the effective seeds, which is associated to the photon that reaches a region of interest in this letter, and then re-run the MC simulation based on the recorded effective seeds, radiative transfer equation (RTE) can be solved by two-step PMC not only with an arbitrary change in the absorption coefficient, but also with large change in the scattering coefficient.

  15. Modeling focusing Gaussian beams in a turbid medium with Monte Carlo simulations.

    PubMed

    Hokr, Brett H; Bixler, Joel N; Elpers, Gabriel; Zollars, Byron; Thomas, Robert J; Yakovlev, Vladislav V; Scully, Marlan O

    2015-04-06

    Monte Carlo techniques are the gold standard for studying light propagation in turbid media. Traditional Monte Carlo techniques are unable to include wave effects, such as diffraction; thus, these methods are unsuitable for exploring focusing geometries where a significant ballistic component remains at the focal plane. Here, a method is presented for accurately simulating photon propagation at the focal plane, in the context of a traditional Monte Carlo simulation. This is accomplished by propagating ballistic photons along trajectories predicted by Gaussian optics until they undergo an initial scattering event, after which, they are propagated through the medium by a traditional Monte Carlo technique. Solving a known problem by building upon an existing Monte Carlo implementation allows this method to be easily implemented in a wide variety of existing Monte Carlo simulations, greatly improving the accuracy of those models for studying dynamics in a focusing geometry.

  16. Photosymbiotic ascidians in Singapore: turbid waters may reduce living space

    PubMed Central

    Su, Shih-Wei; Hirose, Euichi; Chen, Serina Lee Siew; Mok, Michael Hin-Kiu

    2013-01-01

    Abstract The photosymbiotic ascidian fauna at Changi Beach, Pulau Semakau, Sentosa and St. John’s Island, Singapore were surveyed. A total of five species, Diplosoma simile, Lissoclinum bistratum, Lissoclinum punctatum, Lissoclinum timorense and Trididemnum cyclops, were recorded, with Lissoclinum timorense and Trididemnum cyclops being newly recorded in Singapore. However, no photosymbiotic species were found at Changi Beach probably due to the polluted waters in the region. Coastal development has caused Singapore waters to become turbid, leading to decrease in suitable habitats for photosymbiotic ascidians. Clean waters in Pulau Semakau probably provide a better environment for the growth of photosymbiotic ascidians and this area has a greater variety of these ascidians than the other areas in Singapore. Each of the five species has also been recorded in the Ryukyu Archipelago (Japan) and three species (Diplosoma simile, Lissoclinum bistratum and Trididemnum cyclops) have also been recorded in Taiwan. PMID:23794913

  17. Use of a portable electric barrier to estimate Chinook salmon escapement in a turbid Alaskan river

    USGS Publications Warehouse

    Palmisano, A.; Burger, C.V.

    1988-01-01

    We developed a portable electric barrier to aid in the capture of adult chinook salmon Oncorhynchus tshawytscha undergoing spawning migrations up a turbid stream in south-central Alaska. In 1981, we tagged and released 157 chinook salmon after diverting them from the main-stem Killey River into a conventional trap with the aid of the electric barrier. On the basis of returns of tagged salmon to Benjamin Creek, a clear-water tributary of the upper Killey River, we estimated spawners in the drainage to number 8,000 fish. Two different statistical approaches to the mark–recapture data yielded similar estimates. Through several modifications of the electric barrier, we were able to reduce mortality associated with the barrier's use.

  18. Interaction of on-site and near real time measured turbidity and enzyme activity in stream water.

    NASA Astrophysics Data System (ADS)

    Stadler, Philipp; Farnleitner, Andreas H.; Zessner, Matthias

    2013-04-01

    influence of turbidity on rapid GLUC measurements of stream water. During event run off conditions with high sediment load, accuracy of the GLUC determination was assayed. Various on-site set ups were tested to ascertain the use of sample prefiltration. We would like acknowledge financial support from the Austrian Science Funds (FWF) as part of the Vienna Doctoral Programme on Water Resource Systems (DK-plus W1219-N22). References: Cabral, J. P. S. 2010. "Water Microbiology. Bacterial Pathogens and Water." International Journal of Environmental Research and Public Health 7 (10): 3657-3703. Biswal , N. , S. Gupta, N. Ghosh, and A. Pradhan 2003. "Recovery of turbidity free fluorescence from measured fluorescence: An experimental approach. Optics Express 11, (24): 3320. Molina-Munoz, M., J. M. Poyatos, R. Vilchez, E. Hontoria, B. Rodelas, and J. Gonzalez-Lopez. 2007. "Effect of the Concentration of Suspended Solids on the Enzymatic Activities and Biodiversity of a Submerged Membrane Bioreactor for Aerobic Treatment of Domestic Wastewater." Applied Microbiology and Biotechnology 73 (6): 1441-1451. Tryland, I., and L. Fiksdal. 1998. "Enzyme Characteristics of β-d-Galactosidase-and β-d-Glucuronidase-Positive Bacteria and Their Interference in Rapid Methods for Detection of Waterborne Coliforms andEscherichia Coli." Applied and Environmental Microbiology 64 (3): 1018-1023.

  19. Turbidity, light, temperature, and hydropeaking control primary productivity in the Colorado River, Grand Canyon

    USGS Publications Warehouse

    Hall, Robert O.; Yackulic, Charles B.; Kennedy, Theodore A.; Yard, Michael D.; Rosi-Marshall, Emma J.; Voichick, Nicholas; Behn, Kathrine E.

    2015-01-01

    Dams and river regulation greatly alter the downstream environment for gross primary production (GPP) because of changes in water clarity, flow, and temperature regimes. We estimated reach-scale GPP in five locations of the regulated Colorado River in Grand Canyon using an open channel model of dissolved oxygen. Benthic GPP dominates in Grand Canyon due to fast transport times and low pelagic algal biomass. In one location, we used a 738 days time series of GPP to identify the relative contribution of different physical controls of GPP. We developed both linear and semimechanistic time series models that account for unmeasured temporal covariance due to factors such as algal biomass dynamics. GPP varied from 0 g O2 m−2 d−1 to 3.0 g O2 m−2 d−1 with a relatively low annual average of 0.8 g O2 m−2d−1. Semimechanistic models fit the data better than linear models and demonstrated that variation in turbidity primarily controlled GPP. Lower solar insolation during winter and from cloud cover lowered GPP much further. Hydropeaking lowered GPP but only during turbid conditions. Using the best model and parameter values, the model accurately predicted seasonal estimates of GPP at 3 of 4 upriver sites and outperformed the linear model at all sites; discrepancies were likely from higher algal biomass at upstream sites. This modeling approach can predict how changes in physical controls will affect relative rates of GPP throughout the 385 km segment of the Colorado River in Grand Canyon and can be easily applied to other streams and rivers.

  20. Sensitivity of estuarine turbidity maximum to settling velocity, tidal mixing, and sediment supply

    USGS Publications Warehouse

    Warner, J.C.; Sherwood, C.R.; Geyer, W.R.; ,

    2007-01-01

    Estuarine turbidity maximum, numerical modeling, settling velocity, stratification The spatial and temporal distribution of suspended material in an Estuarine Turbidity Maxima (ETM) is primarily controlled by particle settling velocity, tidal mixing, shear-stress thresholds for resuspension, and sediment supply. We vary these parameters in numerical experiments of an idealized two-dimensional (x-z) estuary to demonstrate their affects on the development and retention of particles in an ETM. Parameters varied are the settling velocity (0.01, 0.1, and 0.5 mm/s), tidal amplitude (0.4 m 12 hour tide and 0.3 to 0.6 m 14 day spring neap cycle), and sediment availability (spatial supply limited or unlimited; and temporal supply as a riverine pulse during spring vs. neap tide). Results identify that particles with a low settling velocity are advected out of the estuary and particles with a high settling velocity provide little material transport to an ETM. Particles with an intermediate settling velocity develop an ETM with the greatest amount of material retained. For an unlimited supply of sediment the ETM and limit of salt intrusion co-vary during the spring neap cycle. The ETM migrates landward of the salt intrusion during spring tides and seaward during neap tides. For limited sediment supply the ETM does not respond as an erodible pool of sediment that advects landward and seaward with the salt front. The ETM is maintained seaward of the salt intrusion and controlled by the locus of sediment convergence in the bed. For temporal variability of sediment supplied from a riverine pulse, the ETM traps more sediment if the pulse encounters the salt intrusion at neap tides than during spring tides. ?? 2007 Elsevier B.V. All rights reserved.

  1. Turbidity as a control on phytoplankton biomass and productivity in estuaries

    USGS Publications Warehouse

    Cloern, J.E.

    1987-01-01

    In many coastal plain estuaries light attenuation by suspended sediments confines the photic zone to a small fraction of the water column, such that light limitation is a major control on phytoplankon production and turnover rate. For a variety of estuarine systems (e.g. San Francisco Bay, Puget Sound, Delaware Bay, Hudson River plume), photic-zone productivity can be estimated as a function of phytoplankton biomass times mean irradiance of the photic zone. Net water column productivity also varies with light availability, and in San Francisco Bay net productivity is zero (estimated respiratory loss of phytoplankton balances photosynthesis) when the ratio of photic depth (Zp) to mixed depth (Zm) is less than about 0.2. Thus whenever Zp:Zm < 0.2, the water column is a sink for phytoplankton production. Much of the spatial and temporal variability of phytoplankton biomass or productivity in estuaries is explained by variations in the ratio of photic depth to mixed depth. For example, phytoplankton blooms often coincide with stratification events that reduce the depth of the surface mixed layer (increase Zp:Zm). Shallow estuarine embayments (high Zp:Zm) are often characterized by high phytoplankton biomass relative to adjacent channels (low Zp:Zm). Many estuaries have longitudinal gradients in productivity that mirror the distribution of suspended sediments: productivity is low near the riverine source of sediments (low Zp:Zm) and increases toward the estuary mouth where turbidity decreases. Some of these generalizations are qualitative in nature, and detailed understanding of the interaction between turbidity and estuarine phytoplankton dynamics requires improved understanding of vertical mixing rates and phytoplankton respiration. ?? 1987.

  2. Sea level and turbidity controls on mangrove soil surface elevation change

    USGS Publications Warehouse

    Lovelock, Catherine E.; Fernanda Adame, Maria; Bennion, Vicki; Hayes, Matthew; Reef, Ruth; Santini, Nadia; Cahoon, Donald R.

    2015-01-01

    Increases in sea level are a threat to seaward fringing mangrove forests if levels of inundation exceed the physiological tolerance of the trees; however, tidal wetlands can keep pace with sea level rise if soil surface elevations can increase at the same pace as sea level rise. Sediment accretion on the soil surface and belowground production of roots are proposed to increase with increasing sea level, enabling intertidal habitats to maintain their position relative to mean sea level, but there are few tests of these predictions in mangrove forests. Here we used variation in sea level and the availability of sediments caused by seasonal and inter-annual variation in the intensity of La Nina-El Nino to assess the effects of increasing sea level on surface elevation gains and contributing processes (accretion on the surface, subsidence and root growth) in mangrove forests. We found that soil surface elevation increased with mean sea level (which varied over 250 mm during the study) and with turbidity at sites where fine sediment in the water column is abundant. In contrast, where sediments were sandy, rates of surface elevation gain were high, but not significantly related to variation in turbidity, and were likely to be influenced by other factors that deliver sand to the mangrove forest. Root growth was not linked to soil surface elevation gains, although it was associated with reduced shallow subsidence, and therefore may contribute to the capacity of mangroves to keep pace with sea level rise. Our results indicate both surface (sedimentation) and subsurface (root growth) processes can influence mangrove capacity to keep pace with sea level rise within the same geographic location, and that current models of tidal marsh responses to sea level rise capture the major feature of the response of mangroves where fine, but not coarse, sediments are abundant.

  3. Sea level and turbidity controls on mangrove soil surface elevation change

    NASA Astrophysics Data System (ADS)

    Lovelock, Catherine E.; Adame, Maria Fernanda; Bennion, Vicki; Hayes, Matthew; Reef, Ruth; Santini, Nadia; Cahoon, Donald R.

    2015-02-01

    Increases in sea level are a threat to seaward fringing mangrove forests if levels of inundation exceed the physiological tolerance of the trees; however, tidal wetlands can keep pace with sea level rise if soil surface elevations can increase at the same pace as sea level rise. Sediment accretion on the soil surface and belowground production of roots are proposed to increase with increasing sea level, enabling intertidal habitats to maintain their position relative to mean sea level, but there are few tests of these predictions in mangrove forests. Here we used variation in sea level and the availability of sediments caused by seasonal and inter-annual variation in the intensity of La Nina-El Nino to assess the effects of increasing sea level on surface elevation gains and contributing processes (accretion on the surface, subsidence and root growth) in mangrove forests. We found that soil surface elevation increased with mean sea level (which varied over 250 mm during the study) and with turbidity at sites where fine sediment in the water column is abundant. In contrast, where sediments were sandy, rates of surface elevation gain were high, but not significantly related to variation in turbidity, and were likely to be influenced by other factors that deliver sand to the mangrove forest. Root growth was not linked to soil surface elevation gains, although it was associated with reduced shallow subsidence, and therefore may contribute to the capacity of mangroves to keep pace with sea level rise. Our results indicate both surface (sedimentation) and subsurface (root growth) processes can influence mangrove capacity to keep pace with sea level rise within the same geographic location, and that current models of tidal marsh responses to sea level rise capture the major feature of the response of mangroves where fine, but not coarse, sediments are abundant.

  4. Estimating turbidity current conditions from channel morphology: A Froude number approach

    NASA Astrophysics Data System (ADS)

    Sequeiros, Octavio E.

    2012-04-01

    There is a growing need across different disciplines to develop better predictive tools for flow conditions of density and turbidity currents. Apart from resorting to complex numerical modeling or expensive field measurements, little is known about how to estimate gravity flow parameters from scarce available data and how they relate to each other. This study presents a new method to estimate normal flow conditions of gravity flows from channel morphology based on an extensive data set of laboratory and field measurements. The compilation consists of 78 published works containing 1092 combined measurements of velocity and concentration of gravity flows dating as far back as the early 1950s. Because the available data do not span all ranges of the critical parameters, such as bottom slope, a validated Reynolds-averaged Navier-Stokes (RANS)κ-ɛnumerical model is used to cover the gaps. It is shown that gravity flows fall within a range of Froude numbers spanning 1 order of magnitude centered on unity, as opposed to rivers and open-channel flows which extend to a much wider range. It is also observed that the transition from subcritical to supercritical flow regime occurs around a slope of 1%, with a spread caused by parameters other than the bed slope, like friction and suspended sediment settling velocity. The method is based on a set of equations relating Froude number to bed slope, combined friction, suspended material, and other flow parameters. The applications range from quick estimations of gravity flow conditions to improved numerical modeling and back calculation of missing parameters. A real case scenario of turbidity current estimation from a submarine canyon off the Nigerian coast is provided as an example.

  5. Drinking water turbidity and gastrointestinal illness in the elderly of Philadelphia

    PubMed Central

    Schwartz, J.; Levin, R.; Goldstein, R.

    2000-01-01

    STUDY OBJECTIVE—To investigate the association between drinking water quality and gastrointestinal illness in the elderly of Philadelphia.
DESIGN—Within the general population, children and the elderly are at highest risk for gastrointestinal disease. This study investigates the potential association between daily fluctuations in drinking water turbidity and subsequent hospital admissions for gastrointestinal illness of elderly persons, controlling for time trends, seasonal patterns, and temperature using Poisson regression analysis.
SETTING AND PARTICIPANTS—All residents of Philadelphia aged 65 and older in 1992-1993 were studied through their MEDICARE records.
MAIN RESULTS—For Philadelphia's population aged 65 and older, we found water quality 9 to 11 days before the visit was associated with hospital admissions for gastrointestinal illness, with an interquartile range increase in turbidity being associated with a 9% increase (95% CI 5.3%, 12.7%). In the Belmont service area, there was also an association evident at a lag of 4 to 6 days (9.1% increase, 95% CI 5.2, 13.3). Both associations were stronger in those over 75 than in the population aged 65-74. This association occurred in a filtered water supply in compliance with US standards.
CONCLUSIONS—Elderly residents of Philadelphia remain at risk of waterborne gastrointestinal illness under current water treatment practices. Hospitalisations represent a very small percentage of total morbidity.


Keywords: waterborne disease; drinking water; gastrointestinal illness; elderly PMID:10692962

  6. Pattern of shoreline spawning by sockeye salmon in a glacially turbid lake: evidence for subpopulation differentiation

    USGS Publications Warehouse

    Burger, C.V.; Finn, J.E.; Holland-Bartels, L.

    1995-01-01

    Alaskan sockeye salmon typically spawn in lake tributaries during summer (early run) and along clear-water lake shorelines and outlet rivers during fall (late run). Production at the glacially turbid Tustumena Lake and its outlet, the Kasilof River (south-central Alaska), was thought to be limited to a single run of sockeye salmon that spawned in the lake's clear-water tributaries. However, up to 40% of the returning sockeye salmon enumerated by sonar as they entered the lake could not be accounted for during lake tributary surveys, which suggested either substantial counting errors or that a large number of fish spawned in the lake itself. Lake shoreline spawning had not been documented in a glacially turbid system. We determined the distribution and pattern of sockeye salmon spawning in the Tustumena Lake system from 1989 to 1991 based on fish collected and radiotagged in the Kasilof River. Spawning areas and time were determined for 324 of 413 sockeye salmon tracked upstream into the lake after release. Of these, 224 fish spawned in tributaries by mid-August and 100 spawned along shoreline areas of the lake during late August. In an additional effort, a distinct late run was discovered that spawned in the Kasilof River at the end of September. Between tributary and shoreline spawners, run and spawning time distributions were significantly different. The number of shoreline spawners was relatively stable and independent of annual escapement levels during the study, which suggests that the shoreline spawning component is distinct and not surplus production from an undifferentiated run. Since Tustumena Lake has been fully deglaciated for only about 2,000 years and is still significantly influenced by glacier meltwater, this diversification of spawning populations is probably a relatively recent and ongoing event.

  7. Turbidity as a factor in the decline of Great Lakes fishes with special reference to Lake Erie

    USGS Publications Warehouse

    Van Oosten, John

    1948-01-01

    All of the evidence indicates, then, that soil erosion on farms and the turbidity of the water were not major factors, if operative at all, in the decline of Great Lakes fishes and that they did not make Lake Erie unsuitable for fish life.

  8. Environmental changes and microbiological health risks. Satellite-derived turbidity: an indicator of "health hazard" for surface water in West Africa (Bagre lake, Burkina Faso).

    NASA Astrophysics Data System (ADS)

    Robert, E.; Grippa, M.; Kergoat, L.; Martinez, J.; Pinet, S.; Gal, L.; Soumaguel, N.

    2015-12-01

    A significant correlation exists between the concentration of parasites, bacteria and some water quality parameters including surface suspended solids (SSS) and turbidity. Suspended particles can carry viruses and pathogenic bacteria affecting human health and foster their development. High SSS, associated with high turbidity, can therefore be considered as a vector of microbiological contaminants, causing diarrheal diseases. Few studies have focused on the turbidity parameter in rural Africa, while many cases of intestinal parasitic infections are due to the consumption of unsafe water from ponds, lakes, and rivers. Monitoring turbidity may therefore contribute to health hazard monitoring. Turbidity refers to the optical properties of water and is known to impact water reflectance in the visible and near-infrared domain. Ideally, its spatial and temporal variability requires the use of high temporal resolution (MODIS) and spatial resolution (Landsat, SPOT, Sentinel-2). Here we investigate turbidity in West-Africa. Various algorithms and indices proposed in the literature for inland waters are applied to MODIS series and to Landsat 7 and 8 CDR images, and SPOT5 images. The data and algorithms are evaluated with field measurements: turbidity, SSS, and hyperspectral ground radiometry. We show that turbidity of the Bagre Lake displays a strong increase over 2000-2015, associated with the corresponding increase of the red and NIR reflectances, as well as a reduction of the seasonal variations. Water level derived from the Jason 2 altimeter does not explain such variations. The most probable hypothesis is a change in land use (increase in bare and degraded soils), that leads to an increase in the particles transported by surface runoff to the lake. Such an increase in turbidity reinforces the health risk. We will discuss the link between turbidity and health in view of data from health centers on diarrheal diseases as well as data on practices and uses of populations.

  9. Recent turbidity current activity in sediment-starved submarine canyons (Northwestern Gulf of St. Lawrence, Eastern Canada)

    NASA Astrophysics Data System (ADS)

    Normandeau, Alexandre; Lajeunesse, Patrick; St-Onge, Guillaume; Bourgault, Daniel; Neumeier, Urs

    2016-04-01

    Submarine canyons are known to be main conduits for the transport of sediments to deep-sea basins, mostly by turbidity currents. Turbidity currents flowing in submarine canyons are mostly triggered by hyperpycnal flows, small to large slope failures and advection of shelf sediment offshore. In these contexts, sediment supply is necessary to maintain canyon activity over time. In 2007, a high-resolution mapping of small-scale submarine canyons offshore Pointe-des-Monts (NW Gulf of St. Lawrence, Eastern Canada) revealed a series of incisions characterized by the presence of numerous confined crescentic bedforms. The repeat mapping of the canyons in 2012 and 2015 revealed that the bedforms migrated upslope, indicating that they are cyclic steps produced by supercritical flows. Surprisingly, the comparison of multibeam surveys did not show any evidence of slope failures that could have triggered the turbidity currents responsible for recent bedform migration. Additionally, the rocky shores and coastal shelf do not supply sediments to these canyons, thus excluding turbidity current triggers such as advection of shelf sediments or hyperpycnal flows. In this context, we suggest that hydrodynamic processes are responsible for suspending in-situ sediments, which then may flow as turbidity currents when density of the water-sediment mixture is high enough. ADCPs deployed for 3,5 months during the summer of 2015 revealed along-canyon currents following tidal cycles with speeds up to 0.4 m/s, which were not strong enough to produce bedform migration. Therefore, the currents responsible for bedforms occur during infrequent events or during winter conditions, which both require longer instrument time-series to be observed.

  10. THE IMPACT OF A TANK 40H DECANT ON THE PROJECTED OPERATING WINDOWS FOR SB4 AND GLASS SELECTION STRATEGY IN SUPPORT OF THE VARIABILITY STUDY

    SciTech Connect

    Raszewski, F; Tommy Edwards, T; David Peeler, D

    2008-02-07

    The Liquid Waste Organization (LWO) has requested that the Savannah River National Laboratory (SRNL) to assess the impact of a 100K gallon decant volume from Tank 40H on the existing sludge-only Sludge Batch 4 (SB4)-Frit 510 flowsheet and the coupled operations flowsheet (SB4 with the Actinide Removal Process (ARP)). Another potential SB4 flowsheet modification of interest includes the addition of 3 wt% sodium (on a calcined oxide basis) to a decanted sludge-only or coupled operations flowsheet. These potential SB4 flowsheet modifications could result in significant compositional shifts to the SB4 system. This paper study provides an assessment of the impact of these compositional changes to the projected glass operating windows and to the variability study for the Frit 510-SB4 system. The influence of the compositional changes on melt rate was not assessed in this study nor was it requested. Nominal Stage paper study assessments were completed using the projected compositions for the various flowsheet options coupled with Frit 510 (i.e., variation was not applied to the sludge and frit compositions). In order to gain insight into the impacts of sludge variation and/or frit variation (due to the procurement specifications) on the projected operating windows, three versions of the Variation Stage assessment were performed: (1) the traditional Variation Stage assessment in which the nominal Frit 510 composition was coupled with the extreme vertices (EVs) of each sludge, (2) an a