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Sample records for ahh brod erod

  1. [AHH activity and life environmental factors].

    PubMed

    Nagayama, J

    1987-04-01

    To investigate life environmental factors which affect aryl hydrocarbon hydroxylase (AHH) activity, basal and 3-methylcholanthrene(3-MC)-induced AHH activities were determined by the formation of 3-hydroxybenzo(a)pyrene in cultured lymphocytes obtained from 111 healthy male subjects who lived in Fukuoka Prefecture, Japan. Fold induction (3-MC-induced/basal) was calculated. Relationship between the absolute activities and the fold induction of AHH and life environmental factors was statistically examined. Study of simple correlation indicated the following: Basal AHH activity was positively correlated with age and habitual intake of drugs. Induced AHH activity was positively correlated with coffee intake, smoking and habitual intake of drugs. Fold induction was positively correlated with coffee intake and smoking, and negatively with age. Using multiple regression analysis, habitual intake of drugs showed positive relation to both basal and induced enzyme activity, and age showed positive relation to the basal activity and negative relation to the fold induction.

  2. Contribution of Jan Brod to nephrology.

    PubMed

    Rychlík, Ivan; Matoušovic, Karel

    2011-01-01

    Jan Brod (1912-1985), Professor of Medicine of Charles University, Prague, was one of the outstanding personalities of the Czechoslovak medicine and European nephrology of the 20th century. He was an eminent clinician, teacher and scientist who belonged among the founders of renal medicine in Europe. He grew up in the scientific tradition of Prague and Vienna and he was trained by some outstanding personalities, particularly Paul Wood. He became famous due to his pathophysiological-clinical approach to hypertension, heart and kidney diseases. He was not only interested in renal and cardiac physiology but in the entire clinical nephrology. He was among the first clinicians who started to use creatinine clearance in routine practice. His early work was also performed in the field of acute glomerulonephritis and in interstitial nephritis. Later he was interested in water and electrolytes in heart failure and the pathogenesis of edema, and he published priority data on the hemodynamic pattern in emotional stress. Furthermore, it is for sure that he was one of the first cardionephrologists, too. As early as in 1950, he studied diurnal variation in renal perfusion and urinary output in heart failure and later the effect of the adrenergic blockade on the renal hemodynamics in heart failure. Up to his exile in 1968, he served as the head of the Institute for Cardiovascular Research based in Prague and later on, up to his retirement, as the head of the Department of Nephrology in Hannover. He was a founding member of the International Society of Nephrology and president of its 2nd congress held in Prague in 1963. Throughout his life, Jan Brod remained a political man who voiced his opinions. Despite two exiles, he was always the Czech patriot. He holds a special place in the history of Czechoslovak and European nephrology.

  3. [World war I as seen by Franciscans of Slavonski Brod].

    PubMed

    Balen, Ivica; Jandrić-Balen, Marica

    2015-11-01

    There is a profound and permanent connection between Franciscans and Slavonski Brod (formerly known as Brod na Savi). It has lasted for centuries, as Franciscans were present in the town even during the Turkish occupation. They were the first town pastors after its independence from the Turks in 1691 and are present today with churches, monasteries, and the Franciscan High School, which opened in 1995. Their chronicles describing the events from 1706 to 1932 are an important source of historical information, especially for local historians. This article describes the life of Franciscans in Brod na Savi during the First World War. Initially, they were loyal Austro-Hungarian citizens who passionately believed in the ultimate victory on all fronts. However, war circumstances quickly lead to a disappointment and doubt. Slavic solidarity increased as the war progressed, and in the end Franciscans were delighted with the establishment of the new country of South Slavs, which they perceived as a means to free the nation from the Austrian and Hungarian authorities. Throughout the war, the Convent served as a reserve military hospital with 145 beds for the soldiers and 21 beds for officers.

  4. [World war I as seen by Franciscans of Slavonski Brod].

    PubMed

    Balen, Ivica; Jandrić-Balen, Marica

    2015-11-01

    There is a profound and permanent connection between Franciscans and Slavonski Brod (formerly known as Brod na Savi). It has lasted for centuries, as Franciscans were present in the town even during the Turkish occupation. They were the first town pastors after its independence from the Turks in 1691 and are present today with churches, monasteries, and the Franciscan High School, which opened in 1995. Their chronicles describing the events from 1706 to 1932 are an important source of historical information, especially for local historians. This article describes the life of Franciscans in Brod na Savi during the First World War. Initially, they were loyal Austro-Hungarian citizens who passionately believed in the ultimate victory on all fronts. However, war circumstances quickly lead to a disappointment and doubt. Slavic solidarity increased as the war progressed, and in the end Franciscans were delighted with the establishment of the new country of South Slavs, which they perceived as a means to free the nation from the Austrian and Hungarian authorities. Throughout the war, the Convent served as a reserve military hospital with 145 beds for the soldiers and 21 beds for officers. PMID:27639047

  5. [Mineral oil drinking water pollution accident in Slavonski Brod, Croatia].

    PubMed

    Medverec Knežević, Zvonimira; Nadih, Martina; Josipović, Renata; Grgić, Ivanka; Cvitković, Ante

    2011-12-01

    On 21 September 2008, heavy oil penetrated the drinking water supply in Slavonski Brod, Croatia. The accident was caused by the damage of heat exchange units in hot water supply. The system was polluted until the beginning of November, when the pipeline was treated with BIS O 2700 detergent and rinsed with water. Meanwhile, water samples were taken for chemical analysis using spectrometric and titrimetric methods and for microbiological analysis using membrane filtration and total plate count. Mineral oils were determined with infrared spectroscopy. Of the 192 samples taken for mineral oil analysis, 55 were above the maximally allowed concentration (MAC). Five samples were taken for polycyclic aromatic hydrocarbon (PAH), benzene, toluene, ethylbenzene, and xylene analysis (BTEX), but none was above MAC. Epidemiologists conducted a survey about health symptoms among the residents affected by the accident. Thirty-six complained of symptoms such as diarrhoea, stomach cramps, vomiting, rash, eye burning, chills, and gastric disorders.This is the first reported case of drinking water pollution with mineral oil in Slavonski Brod and the accident has raised a number of issues, starting from poor water supply maintenance to glitches in the management of emergencies such as this.

  6. Effects of structure on binding to the 2,3,7,8-TCDD receptor protein and AHH induction--halogenated biphenyls.

    PubMed Central

    Safe, S; Bandiera, S; Sawyer, T; Zmudzka, B; Mason, G; Romkes, M; Denomme, M A; Sparling, J; Okey, A B; Fujita, T

    1985-01-01

    The quantitative structure-activity relationships (QSARs) for polychlorinated biphenyl (PCB) congeners have been determined by comparing the EC50 values for three in vitro test systems, namely, aryl hydrocarbon hydroxylase (AHH) and ethoxyresorufin O-deethylase (EROD) induction in rat hepatoma H-4-II-E cells and competitive binding avidities to the rat cytosolic receptor protein (using 2,3,7,8-tetrachlorodibenzo-p-dioxin as a radioligand). For several PCB congeners that are in vivo inducers of rat hepatic microsomal AHH, there was a linear correlation between the -log EC50 values for receptor and the -log EC50 values for AHH (or EROD) induction; moreover, a comparable linear relationship was observed between the -log EC50 values for AHH and EROD induction. Previous in vivo studies have shown that the most active PCB congeners 3,3',4,4'-tetra-, 3,4,4',5-tetra-, 3,3',4,4',5-penta-, and 3,3',4,4',5,5'-hexachlorobiphenyl, cause many of the biologic and toxic effects reported for the highly toxic halogenated aryl hydrocarbon, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). Moreover, the monoortho-substituted homologs of the four coplanar PCBs also elicit comparable in vivo biologic and toxic responses. It was evident from the QSARs for PCBs that there was an excellent correspondence between the in vivo and in vitro potencies of the individual PCB congeners. The effects of substituents on both receptor binding and AHH/EROD induction was determined for a series of 4'-substituted (X)-2,3,4,5-tetrachlorobiphenyls (where X = H, Cl, Br, I, OH, OCH3, NO2, COCH3, F, CF3, CH3, C2H5, i-C3H7, n-C4H9 and t-C4H9). Not unexpectedly, there was a linear relationship between the -log EC50 values for AHH and EROD induction, and these results confirm that both enzymatic oxidations are catalyzed by the same cytochrome P-450 isozyme(s). The effects of substituent structure on receptor binding for 12 substituents was subjected to multiple regression analysis which correlates the relative binding

  7. Eroded Surfaces

    NASA Technical Reports Server (NTRS)

    2003-01-01

    [figure removed for brevity, see original site]

    Released 19 August 2003

    The knobby terrain and eroded impact crater observed in this THEMIS image of the Eumenides Dorsum region are evidence to a surface that has been heavily modified and stripped over time. Variable layering of material within the impact crater suggest a succession of events which eroded the surface and exposed possibly different units. Slope streaks and dust avalanches are also observed within the impact crater and point to recent and continued modification of the surface.

    Image information: VIS instrument. Latitude 4.9, Longitude 203.6 East (156.4 West). 19 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  8. Acquired Hypogonadotropic Hypogonadism (AHH) in Thalassaemia Major Patients: An Underdiagnosed Condition?

    PubMed Central

    De Sanctis, Vincenzo; Elsedfy, Heba; Soliman, Ashraf T; Elhakim, Ihab Zaki; Pepe, Alessia; Kattamis, Christos; Soliman, Nada A.; Elalaily, Rania; El Kholy, Mohamed; Yassin, Mohamed

    2016-01-01

    Introduction In males, acquired hypogonadotropic hypogonadism (AHH) includes all disorders that damage or alter the function of gonadotropin-releasing hormone (GnRH) neurons and/or pituitary gonadotroph cells. The clinical characteristics of AHH are androgen deficiency and lack, delay or halt of pubertal sexual maturation. AHH lead to decreased libido, impaired erectile function, and strength, a worsened sense of well-being and degraded quality of life (QOL). Patients and methods We studied 11 adult men with thalassemia major (TM) aged between 26 to 54 years (mean ± SD: 34.3 ± 8.8 years) with AHH. Twelve age- and sex-matched TM patients with normal pubertal development were used as a control group. All patients were on regular transfusions and iron chelation therapy. Fasting venous blood samples were collected two weeks after transfusion to measure serum concentrations of IGF-1, free thyroxine (FT4), thyrotropin (TSH), cortisol, luteinizing hormone (LH), follicle stimulating hormone (FSH), total testosterone (TT), prolactin and estradiol (E2), glucose, urea, creatinine and electrolytes (including calcium and phosphate). Liver functions and screening for hepatitis C virus seropositivity (HCVab and HCV-RNA) were performed. Iron status was assessed by measuring serum ferritin levels, and evaluation of iron concentrations in the liver (LIC) and heart using MRI- T2*. Bone mineral density was measured at the lumbar spine (L1–L4) for all patients with AHH by dual energy X-ray absorptiometry (DXA) using Hologic QDR 4000 machine. Results The mean basal serum LH and FSH concentrations in AHH patients were 2.4 ± 2.2 IU/L and 1.2 ± 0.9 IU/L respectively; these, values were significantly lower compared to the control group. Semen analysis in 5 patients with AHH showed azoospermia in 3 and oligoasthenozoospermia in 2. The percentage of patients with serum ferritin level >2000 ng/ml (severe iron load) was significantly higher in AHH patients compared to controls, 5/11 (45

  9. Wind-Eroded Landscape

    NASA Technical Reports Server (NTRS)

    2005-01-01

    5 August 2005 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a dust-mantled, wind-eroded landscape in the Medusae Sulci region of Mars. Wind eroded the bedrock in this region, and then, later, windblown dust covered much of the terrain.

    Location near: 5.7oS, 160.2oW Image width: width: 3 km (1.9 mi) Illumination from: lower left Season: Southern Spring

  10. Protective activity of C-geranylflavonoid analogs from Paulownia tomentosa against DNA damage in 137Cs irradiated AHH-1 cells.

    PubMed

    Moon, Hyung-In; Jeong, Min Ho; Jo, Wol Soon

    2014-09-01

    Radiotherapy is an important form of treatment for a wide range of cancers, but it can damage DNA and cause adverse effects. We investigated if the diplacone analogs of P. tomentosa were radio-protective in a human lymphoblastoid cell line (AHH-1). Four geranylated flavonoids, diplacone, 3'-O-methyl-5'-hydroxydiplacone, 3'-O-methyl-5'-O-methyldiplacone and 3'-O-methyldiplacol, were tested for their antioxidant and radio-protective effects. Diplacone analogs effectively scavenged free radicals and inhibited radiation-induced DNA strand breaks in vitro. They significantly decreased levels of reactive oxygen species and cellular DNA damage in 2 Gy-irradiated AHH-1 cells. Glutathione levels and superoxide dismutase activity in irradiated AHH-1 cells increased significantly after treatment with these analogs. The enhanced biological anti-oxidant activity and radioprotective activity of diplacone analogs maintained the survival of irradiated AHH-1 cells in a clonogenic assay. These data suggest that diplacone analogs may protect healthy tissue surrounding tumor cells during radiotherapy to ensure better control of radiotherapy and allow higher doses of radiotherapy to be employed. PMID:25918796

  11. Eroded Sedimentary Rock

    NASA Technical Reports Server (NTRS)

    2003-01-01

    MGS MOC Release No. MOC2-372, 26 May 2003

    This high resolution Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows eroded, layered sedimentary rock exposures in an unnamed western Arabia Terra crater at 8oN, 7oW. The dark material is windblown sand; much of the erosion of these layers may have also been caused by wind. Sunlight illuminates the scene from the left.

  12. [Health and social conditions in Brod na Savi during World War I].

    PubMed

    Jandrić-Balen, Marica; Balen, Ivica

    2015-11-01

    During World War I, social and health conditions were difficult in Brod na Savi, as it stationed a large number of troops, and the military hospital was crowded with patients. With so many able-bodied men and breadwinners mobilised, the town's economy verged on the brink of poverty, but people managed to keep starvation at bay. The most common diseases among civilians were tuberculosis, malaria, intestinal infectious diseases, diphtheria, and venereal diseases, and in 1915 cholera broke out that lasted five months. At the end of 1918 "Spanish flu" also hit the town. The number of wounded and sick soldiers occasionally surpassed the hospital's capacity, so they had to be stationed at the local school facilities for a while. Over two thousand people died in the military hospital, which suggests that the total number of patients who went through the hospital had to be very large. Unfortunately, there are no records to show the hospital's mortality rate or disease prevalence. We are currently trying to establish the demographics of the 2000 dead buried at the local cemetery during WWI using the death records we have.

  13. [Health and social conditions in Brod na Savi during World War I].

    PubMed

    Jandrić-Balen, Marica; Balen, Ivica

    2015-11-01

    During World War I, social and health conditions were difficult in Brod na Savi, as it stationed a large number of troops, and the military hospital was crowded with patients. With so many able-bodied men and breadwinners mobilised, the town's economy verged on the brink of poverty, but people managed to keep starvation at bay. The most common diseases among civilians were tuberculosis, malaria, intestinal infectious diseases, diphtheria, and venereal diseases, and in 1915 cholera broke out that lasted five months. At the end of 1918 "Spanish flu" also hit the town. The number of wounded and sick soldiers occasionally surpassed the hospital's capacity, so they had to be stationed at the local school facilities for a while. Over two thousand people died in the military hospital, which suggests that the total number of patients who went through the hospital had to be very large. Unfortunately, there are no records to show the hospital's mortality rate or disease prevalence. We are currently trying to establish the demographics of the 2000 dead buried at the local cemetery during WWI using the death records we have. PMID:27639040

  14. Monooxygenase activity and contaminant burdens of pipping heron embryos in Virginia, the Great Lakes and San Francisco Bay

    USGS Publications Warehouse

    Rattner, B.A.; Melancon, M.J.; Custer, T.W.; Hothem, R.L.; King, K.A.; LeCaptain, L.J.; Spann, J.W.

    1991-01-01

    Black-crowned night-heron (Nvcticorax nvcticorax) pipping embryos were studied from undisturbed (Chincoteague National Wildl ife Refuge, VA) and industrialized (Cat Island, Green Bay WI, and Bair and W. Marin Islands, San Francisco Bay, CA) locations. Hepatic aryl hydrocarbon hydroxylase (AHH) , ethoxyresorufin-O-dealkylase, (EROD), benzyloxyROD (BROD), pentoxyROD (PROD) and ethoxycoumarinOD (ECOD) activities and burdens of organochlorines (embryo + yolk sac - liver) were quantified. AHH, BROD, ECOD and EROD were induced up to 100-fold (P<.O5) in embryos from Cat Island compared to the other sites. Greatest burdens of total PCBs and p,p?DDE were detected in Cat Island embryos. Monooxygenase activities (AHH, BROD, ECOD and EROD) and PCB concentrations were significantly correlated (r=O.50 to 0.72). These and other data indicate that monooxygenases may be rapid and inexpensive biomarkers of exposure to some PCB congeners. Current efforts include determination of PCB congeners and other contaminants in these embryos, additional characterization of the induced P-450 isozymes, and expanding the study to include heron embryos and nestlings at other estuaries.

  15. Monooxygenase activity of black-crowned night-heron (BCNH) nestlings in Virginia, the Great Lakes and San Francisco Bay

    USGS Publications Warehouse

    Rattner, B.A.; Melancon, M.J.; Custer, T.W.; Hothem, R.L.; King, K.A.; LeCaptain, L.J.; Spann, J.W.

    1990-01-01

    To evaluate cytochrome P-450 related parameters as biomarkers of pollutant exposure, rates of arylhydrocarbon hydroxylase (AHH), ethoxyresorufin-O-deethylase (EROD), benzyloxyROD (BROD), pentoxyROD (PROD) and ethoxycoumarinOD (ECOD) were studied in 10-day-old BCNHs (Nycticorax nycticorax). Nestlings were collected from Chincoteague National Wildlife Refuge, VA ('controls') and from polluted sites including. Cat Island, Green Bay, WI, and Bair and West Marin Islands, San Francisco Bay, CA. Livers were frozen (-70.C) for monooxygenase assays and SDS-PAGE. Microsomal AHH and BROD activities were greater (P2 standard deviations from the control mean (induced up to 3-fold). EROD, PROD and ECOD did not differ among sites. Absence of an EROD response with AHH and BROD induction in BCNHs is different than responses in other species. The association of pollutant burdens with P-450 parameters is being studied. These biomarkers may serve as a rapid screen of exposure in a national contaminant biomonitoring program and other assessment activities.

  16. Erodibility characteristics of embankment materials

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Erosion is one of the least reliably defined elements of many hydraulic projects. Earthen embankments (i.e. dams and levees) are an example of hydraulic projects in which erosion and material erodibility have not been reliably defined in the past. Recent as well as past embankment failures have he...

  17. Biomonitoring environmental contamination with pipping black-crowned night heron embryos: Induction of cytochrome P450

    USGS Publications Warehouse

    Rattner, B.A.; Melancon, M.J.; Custer, T.W.; Hothem, R.L.; King, K.A.; LeCaptain, L.J.; Spann, J.W.; Woodin, Bruce R.; Stegeman, John J.

    1993-01-01

    Cytochrome P450-associated monooxygenase activities and cytochrome P450 proteins were measured in pipping black-crowned night heron (Nycticorax nycticorax) embryos collected from a reference site (next to the Chincoteague National Wildlife Refuge, VA) and three polluted sites (Cat Island, Green Bay, Lake Michigan, WI; Bair Island, San Francisco Bay, CA; West Marin Island, San Francisco Bay, CA). In a laboratory study, artificially incubated night heron embryos from the reference site were treated with 3-methylcholanthrene (200 mu-g administered into the air cell 2 d before pipping) or phenobarbital (2 mg daily for 2 d before pipping). Compared to controls (untreated + vehicle-treated embryos), 3-methylcholanthrene induced a greater than five-fold increase in activities of several monooxygenases (arylhydrocarbon hydroxylase, AHH; benzyloxyresorufin-O-dealkylase, BROD; ethoxyresorufin-O-dealkylase, EROD; pentoxyresorufin-O-dealkylase, PROD) and a greater than 100-fold increase in the concentration of immunodetected cytochrome P450 1A (CYP1A). Phenobarbital treatment resulted in only a slight increase in BROD activity but induced proteins recognized by antibodies to cytochrome P450 2B (CYP2B) by 2,000-fold. In a field study, activities of AHH, BROD, EROD, and ethoxycoumarin-O-dealkylase (ECOD) were up to 85-fold higher in pipping black-crowned night herons collected from Cat Island compared to other sites. Hepatic CYP1A and CYP2B cross-reactive proteins were detected in significantly more individuals from Cat Island than from the reference site. Greatest burdens of total PCBs and p, p'-DDE were detected in embryos from Cat Island. Cytochrome P450-associated monooxygenase activities and cytochrome P450 proteins (AHH, BROD, EROD, ECOD, CYP1A, CYP2B) were significantly associated with total PCB burdens (r = 0.50-0.72). These data indicate that cytochrome P450 may be a useful biomarker of exposure to some PCB mixtures in black-crowned night heron embryos.

  18. Biomonitoring environmental contamination with pipping black-crowned night heron embryos: Induction of cytochrome P450

    USGS Publications Warehouse

    Rattner, B.A.; Melancon, M.J.; Custer, T.W.; Hothem, R.L.; King, K.A.; LeCaptain, L.J.; Spann, J.W.; Woodin, Bruce R.; Stegeman, John J.

    1993-01-01

    Cytochrome P450-associated monooxygenase activities and cytochrome P450 proteins were measured in pipping black-crowned night heron (Nycticorax nycticorax) embryos collected from a reference site (next to the Chincoteague National Wildlife Refuge, VA) and three polluted sites (Cat Island, Green Bay, Lake Michigan, WI; Bair Island, San Francisco Bay, CA; West Marin Island, San Francisco Bay, CA). In a laboratory study, artificially incubated night heron embryos from the reference site were treated with 3-methylcholanthrene (200 mu g administered into the air cell 2 d before pipping) or phenobarbital (2 mg daily for 2 d before pipping). Compared to controls (untreated + vehicle-treated embryos), 3-methylcholanthrene induced a greater than fivefold increase in activities of several monooxygenases (arylhydrocarbon hydroxylase, AHH; benzyloxyresorufin-O-dealkylase, BROD; ethoxyresorufin-O-dealkylase, EROD; pentoxyresorufin-O- dealkylase, PROD) and a greater than 100-fold increase in the concentration of immunodetected cytochrome P450 1A (CYP1A). Phenobarbital treatment resulted in only a slight increase in BROD activity but induced proteins recognized by antibodies to cytochrome P450 2B (CYP2B) by 2,000-fold. In a field study, activities of AHH, BROD, EROD, and ethoxycoumarin-O-dealkylase (ECOD) were up to 85-fold higher in pipping black- crowned night herons collected from Cat Island compared to other sites. Hepatic CYP1A and CYP2B cross- reactive proteins were detected in significantly more individuals from Cat Island than from the reference site. Greatest burdens of total PCBs and p,p'-DDE were detected in embryos from Cat Island. Cytochrome P450- associated monooxygenase activities and cytochrome P450 proteins (AHH, BROD, EROD, ECOD, CYP1A, CYP2B) were significantly associated with total PCB burdens (r = 0.50-0.72). These data indicate that cytochrome P450 may be a useful biomarker of exposure to some PCB mixtures in black-crowned night heron embryos.

  19. Biomonitoring environmental contamination with pipping black-crowned night heron embryos: Induction of cytochrome P450

    SciTech Connect

    Rattner, B.A.; Melancon, M.J.; Custer, T.W.; Hothem, R.L.; King, K.A.; LeCaptain, L.J.; Spann, J.W. . Patuxent Wildlife Research Center); Woodin, B.R.; Stegeman, J.J. )

    1993-09-01

    Cytochrome P450-associated monooxygenase activities and cytochrome P450 proteins were measured in pipping black-crowned night heron (Nycticorax nycticorax) embryos collected from a reference site (next to the Chincoteague National Wildlife Refuge, VA) and three polluted sites (Cat Island, Green Bay, Lake Michigan, WI; Bair Island, San Francisco Bay, CA; West Marin Island, San Francisco Bay, CA). In a laboratory study, artificially incubated night heron embryos from the reference site were treated with 3-methylcholanthrene or phenobarbital. Compared to controls, 3-methylcholanthrene induced a greater than fivefold increase in activities of several monooxygenases and a greater than 100-fold increase in the concentration of immunodetected cytochrome P450 1A (CYP1A). Phenobarbital treatment resulted in only a slight increase in BROD activity but induced proteins recognized by antibodies to cytochrome P450 2B (CYP2B) by 2,000-fold. In a field study, activities of AHH, BROD, EROD, and ethoxycoumarin-O-dealkylase (ECOD) were up to 85-fold higher in pipping black-crowned night herons collected from Cat Island compared to other sites. Hepatic CYP1A and CYP2B cross-reactive proteins were detected in significantly more individuals from Cat Island than from the reference site. Greatest burdens of total PCBs and p,p[prime]-DDE were detected in embryos from Cat Island. Cytochrome P450-associated monooxygenase activities and cytochrome P450 proteins (AHH, BROD, EROD, ECOD, CYP1A, CYP1B) were significantly associated with total PCB burdens.

  20. Linking nutrient enrichment, sediment erodibility and biofilms

    NASA Astrophysics Data System (ADS)

    Conrad, B.; Mahon, R.; Sojka, S. L.

    2014-12-01

    Sediment movement in coastal lagoons affects nutrient flux and primary producer growth. Previous research has shown that sediment erodibility is affected by biofilm concentration and that growth of benthic organisms, which produce biofilm, is affected by nutrient enrichment. However, researchers have not examined possible links between nutrient addition and sediment erodibility. We manipulated nutrient levels in the water column of 16 microcosms filled with homogenized sediment from a shallow coastal lagoon and artificial seawater to determine the effects on biofilm growth, measured through chlorophyll a and colloidal carbohydrate concentrations. Erosion tests using a Gust microcosm were conducted to determine the relationship between sediment erodibility and biofilm concentration. Results show that carbohydrate levels decreased with increasing nutrient enrichment and were unrelated to chlorophyll concentrations and erodibility. The nutrient levels did not predictably affect the chlorophyll levels, with lower chlorophyll concentrations in the control and medium enrichment treatments than the low and high enrichment treatments. Controls on biofilm growth are still unclear and the assumed relationship between carbohydrates and erodibility may be invalid. Understanding how biofilms respond to nutrient enrichment and subsequent effects on sediment erodibility is essential for protecting and restoring shallow coastal systems.

  1. 7 CFR 12.22 - Highly erodible field determination criteria.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 1 2014-01-01 2014-01-01 false Highly erodible field determination criteria. 12.22 Section 12.22 Agriculture Office of the Secretary of Agriculture HIGHLY ERODIBLE LAND AND WETLAND CONSERVATION Highly Erodible Land Conservation § 12.22 Highly erodible field determination criteria....

  2. 7 CFR 12.22 - Highly erodible field determination criteria.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 1 2013-01-01 2013-01-01 false Highly erodible field determination criteria. 12.22 Section 12.22 Agriculture Office of the Secretary of Agriculture HIGHLY ERODIBLE LAND AND WETLAND CONSERVATION Highly Erodible Land Conservation § 12.22 Highly erodible field determination criteria....

  3. 7 CFR 12.22 - Highly erodible field determination criteria.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 1 2011-01-01 2011-01-01 false Highly erodible field determination criteria. 12.22 Section 12.22 Agriculture Office of the Secretary of Agriculture HIGHLY ERODIBLE LAND AND WETLAND CONSERVATION Highly Erodible Land Conservation § 12.22 Highly erodible field determination criteria....

  4. 7 CFR 12.22 - Highly erodible field determination criteria.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 1 2012-01-01 2012-01-01 false Highly erodible field determination criteria. 12.22 Section 12.22 Agriculture Office of the Secretary of Agriculture HIGHLY ERODIBLE LAND AND WETLAND CONSERVATION Highly Erodible Land Conservation § 12.22 Highly erodible field determination criteria....

  5. Metolachlor dissipation in eroded and restored landscapes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In hilly landforms subject to long-term cultivation, erosion has denuded upper slope positions of topsoil and accumulated topsoil in lower slope positions. Landscape restoration is one approach to remediate these eroded landforms by moving soil from areas of topsoil accumulation to areas of topsoil ...

  6. Authority Grab Eroding Stature of State Boards

    ERIC Educational Resources Information Center

    McNeil, Michele

    2008-01-01

    This article reports on the eroding power of state school boards in the U.S. as lawmakers and governors are seeking to expand their authority over K-12 education and, in some cases, reverse education policy set in motion by elected or appointed panels. This year alone, state boards in Florida, Ohio, and Vermont are targets of legislation that…

  7. Coupled length scales in eroding landscapes

    SciTech Connect

    Chan, Kelvin K.; Rothman, Daniel H.

    2001-05-01

    We report results from an empirical study of the anisotropic structure of eroding landscapes. By constructing a novel correlation function, we show quantitatively that small-scale channel-like features of landscapes are coupled to the large-scale structure of drainage basins. We show additionally that this two-scale interaction is scale-dependent. The latter observation suggests that a commonly applied effective equation for erosive transport may itself depend on scale.

  8. Soil quality changes after topsoil addition to eroded land

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soil-landscape rehabilitation within eroded fields can be accomplished by moving topsoil from depositional to eroded landscape positions. The purpose is to improve soil quality and productivity of the upper root zone in eroded areas of the field. Changes in soil quality may be estimated through chan...

  9. 7 CFR 12.22 - Highly erodible field determination criteria.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... of changing field boundaries. When field boundaries are changed to include areas of land that were... Section 12.22 Agriculture Office of the Secretary of Agriculture HIGHLY ERODIBLE LAND AND WETLAND CONSERVATION Highly Erodible Land Conservation § 12.22 Highly erodible field determination criteria....

  10. Relationships among cytochromes P450 and dioxin equivalents in pipping heron embryos from Virginia, the Great Lakes and San Francisco Bay

    USGS Publications Warehouse

    Rattner, B.A.; Hatfield, J.S.; Melancon, M.J.; Custer, T.W.; Tillett, D.E.

    1993-01-01

    Pipping black-crowned night-heron (Nycticorax nycticorax) embryos were collected from undisturbed (Chincoteague National Wildlife Refuge, VA) and industrialized (Cat Island, Green Bay, WI; San Francisco Bay, CA) locations. Hepatic P450 associated monooxygenases (AHH, EROD, BROD, ECOD) and P450 proteins (CYP1A, CYP2B) were induced up to 85-fold, and were associated with burdens of total PCBs and 11 AHH-active PCB congeners. Dioxin equivalents (TCDD-EQs) of sample extracts, derived by bioassay (H4I1E rat hepatoma cell) and mathematically (product of PCB congener concentration and relative TCDD potency), revealed greatest TCDD-EQs in Cat Island samples. TCDD-EQs were associated with P450s, especially BROD, EROD and CYP1A (r2 = 0.35 to 0.66). TCDD-EQs derived by bioassay were highly correlated with TCDD-EQs derived mathematically (r2 = 0.58 to 0.67) . Multiple regressions were also performed to investigate relationships among P450s and PCB congeners. In summary, these data demonstrate that hepatic P450s of heron embryos are biomarkers of exposure to dioxin-like compounds and provide further evidence that this species has considerable value for assessing wetland and estuarine contamination.

  11. Submerged and eroded drumlins off northeastern Massachusetts

    USGS Publications Warehouse

    Oldale, R.N.; Knebel, H. J.; Bothner, Michael H.

    1994-01-01

    Streamlined, oval-shaped, oriented topographic highs in Massachusetts Bay are identified as the erosional remnants of drumlins. The topographic highs correlate with outlines of lag gravel deposits on the sea floor and both the highs and lag gravel seafloor footprint have a distinct east-southeast long axis trend. This trend is similar to the preferred orientation of the long axes of drumlins in the Boston Basin and indicates the flow direction of the late Wisconsinan Laurentide Ice Sheet. Modification of the drumlins occurred during two passages of the shoreline, the first during the late Wisconsinan regression when the drumlins were only slightly eroded. The second passage of the shoreline occurred during the marine transgression, when erosion, in the form of cliff-face retreat, removed the upper part of the drumlins. ?? 1994.

  12. Eroded Layered Material in Southwest Utopia Planitia

    NASA Technical Reports Server (NTRS)

    1999-01-01

    Images from the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC)dramatically illustrate that many places on the red planet have outcrops of layered geologic materials. The two pictures above show the remains of layered material inside craters in southwestern Utopia Planitia (see inset for detailed view). These remnant layers indicate that the craters--and perhaps the plains that surround them--were once buried beneath a deposit that has since been eroded away. This theme of layered outcrops and exhumed craters appears to be one of the dominant observations that MGS MOC has made--to date--about Mars. The origin and composition of the layered material--and its ultimate fate once it was largely eroded away--are unknown.

    Each of the two pictures shown here covers an area about 4 kilometers (2.5 miles)by 6.3 kilometers (3.9 miles). Illumination is from the lower right. These are subframes of a single MOC image acquired in July 1998 during the MGS Science Phasing Orbits imaging campaign. This figure was presented at the 30th Lunar and Planetary Science Conference in Houston, Texas, March 1999.

    Malin Space Science Systems and the California Institute of Technology built the MOC using spare hardware from the Mars Observer mission. MSSS operates the camera from its facilities in San Diego, CA. The Jet Propulsion Laboratory's Mars Surveyor Operations Project operates the Mars Global Surveyor spacecraft with its industrial partner, Lockheed Martin Astronautics, from facilities in Pasadena, CA and Denver, CO.

  13. Mini rainfall simulation for assessing soil erodibility

    NASA Astrophysics Data System (ADS)

    Peters, Piet; Palese, Dina; Baartman, Jantiene

    2016-04-01

    The mini rainfall simulator is a small portable rainfall simulator to determine erosion and water infiltration characteristics of soils. The advantages of the mini rainfall simulator are that it is suitable for soil conservation surveys and light and easy to handle in the field. Practical experience over the last decade has shown that the used 'standard' shower is a reliable method to assess differences in erodibility due to soil type and/or land use. The mini rainfall simulator was used recently in a study on soil erosion in olive groves (Ferrandina-Italy). The propensity to erosion of a steep rain-fed olive grove (mean slope ~10%) with a sandy loam soil was evaluated by measuring runoff and sediment load under extreme rain events. Two types of soil management were compared: spontaneous grass as a ground cover (GC) and tillage (1 day (T1) and 10 days after tillage (T2)). Results indicate that groundcover reduced surface runoff to approximately one-third and soil-losses to zero compared with T1. The runoff between the two tilled plots was similar, although runoff on T1 plots increased steadily over time whereas runoff on T2 plots remained stable.

  14. Fractality of eroded coastlines of correlated landscapes

    NASA Astrophysics Data System (ADS)

    Morais, P. A.; Oliveira, E. A.; Araújo, N. A. M.; Herrmann, H. J.; Andrade, J. S., Jr.

    2011-07-01

    Using numerical simulations of a simple sea-coast mechanical erosion model, we investigate the effect of spatial long-range correlations in the lithology of coastal landscapes on the fractal behavior of the corresponding coastlines. In the model, the resistance of a coast section to erosion depends on the local lithology configuration as well as on the number of neighboring sea sides. For weak sea forces, the sea is trapped by the coastline and the eroding process stops after some time. For strong sea forces erosion is perpetual. The transition between these two regimes takes place at a critical sea force, characterized by a fractal coastline front. For uncorrelated landscapes, we obtain, at the critical value, a fractal dimension D=1.33, which is consistent with the dimension of the accessible external perimeter of the spanning cluster in two-dimensional percolation. For sea forces above the critical value, our results indicate that the coastline is self-affine and belongs to the Kardar-Parisi-Zhang universality class. In the case of landscapes generated with power-law spatial long-range correlations, the coastline fractal dimension changes continuously with the Hurst exponent H, decreasing from D=1.34 to 1.04, for H=0 and 1, respectively. This nonuniversal behavior is compatible with the multitude of fractal dimensions found for real coastlines.

  15. Hepatic microsomal cytochromes P450 in mink fed Saginaw Bay carp (SBC)

    USGS Publications Warehouse

    Melancon, M.J.; LeCaptain, L.; Rattner, B.A.; Heaton, S.; Aulerich, R.; Tillitt, D.; Stegeman, John J.; Woodin, B.

    1992-01-01

    Livers from mink fed diets containing 0% (n = 12), 10% (n = 11), 20% (n = 12) and 40% (n = 10) SBC for 6 months contained 0.1, 2.2, 3.6, and 6.3 ug/g total PCBs, respectively. Hepatic microsomes were prepared and assayed for protein, arylhydrocarbon hydroxylase (AHH), benzyloxyresorufin-O-dealkylase (BROD), ethoxy-ROD (ER0D), pentoxy-ROD (PROD), and ethoxycoumarin-OD (ECOD). Mink fed SBC had increased AHH, EROD, and ECOD (group means 2.2-3.4 X control means), decreased BROD and unchanged PROD (the latter 2 assays indicators for phenobarbital-type induction in mammals). Three samples from each group were examined by western blot using a polyclonal anti-P450llB antibody and a monoclonal anti-P450lA antibody (MAb 1-12-3). Mink fed SBC showed induction of a protein recognized by anti-P450lA (8 X control), but had little protein recognized by anti-P450IlB. The monooxygenase activities and western blot data give a consistent picture of MC-type but not PB-type induction in mink fed SBC.

  16. Landslide boost from entrainment of erodible material along the slope

    NASA Astrophysics Data System (ADS)

    Farin, M.; Mangeney, A.; Roche, O.; Ionescu, I.; Hungr, O.

    2011-12-01

    Landslides, debris flows, pyroclastic flows and avalanches are natural hazards that threaten life and property in mountainous, volcanic, coastal and seismically active areas. The granular mass tends to accelerate as gravity pulls it down the slope, and will slow on more gentle slopes, when interaction forces dissipating energy overcome the driving forces. The entrainment of underlying sediments or debris into the gravitational granular flows is suspected to be critical to their dynamics, but direct measurement of material entrainment in natural flows is very difficult. Nevertheless, qualitative and quantitative field observations suggest that material entrainment can either increase or decrease flow velocity and deposit extent, depending on the geological setting and the type of gravitational flow. Based on laboratory experiments on dry granular flows, we show here that erosion of granular material already present on the bed can significantly increase the size and mobility of the flow and possibly generate surges. We present laboratory experiments of granular material flowing over an inclined plane covered by an erodible bed, designed to mimic erosion processes of natural flows traveling over deposits built up by earlier events. The controlling parameters are the inclination of the plane and the thickness of the erodible layer. Different methods are used to prepare the erodible bed, thus leading to various degrees of compaction. We show that erosion processes increases the flow mobility (i. e. runout) by up to 40 % over slopes with inclination close to the repose angle of the grains. The effect is observed even for very thin erodible beds. We demonstrate that the increase of mass of the flowing grains caused by entrainment of the erodible layer is not enough to explain the observed increase in velocity and runout of the granular mass. Erosion efficiency is shown to strongly depend on the slope and on the nature (i. e. degree of compaction) of the erodible bed

  17. Estimate Soil Erodibility Factors Distribution for Maioli Block

    NASA Astrophysics Data System (ADS)

    Lee, Wen-Ying

    2014-05-01

    The natural conditions in Taiwan are poor. Because of the steep slopes, rushing river and fragile geology, soil erosion turn into a serious problem. Not only undermine the sloping landscape, but also created sediment disaster like that reservoir sedimentation, river obstruction…etc. Therefore, predict and control the amount of soil erosion has become an important research topic. Soil erodibility factor (K) is a quantitative index of distinguish the ability of soil to resist the erosion separation and handling. Taiwan soil erodibility factors have been calculated 280 soil samples' erodibility factors by Wann and Huang (1989) use the Wischmeier and Smith nomorgraph. 221 samples were collected at the Maioli block in Miaoli. The coordinates of every sample point and the land use situations were recorded. The physical properties were analyzed for each sample. Three estimation methods, consist of Kriging, Inverse Distance Weighted (IDW) and Spline, were applied to estimate soil erodibility factors distribution for Maioli block by using 181 points data, and the remaining 40 points for the validation. Then, the SPSS regression analysis was used to comparison of the accuracy of the training data and validation data by three different methods. Then, the best method can be determined. In the future, we can used this method to predict the soil erodibility factors in other areas.

  18. The Endoscopic Removal of Eroded Foreign Bodies in the Ureter.

    PubMed

    Kurz, David Anthony; Mucksavage, Phillip

    2016-01-01

    A complication of using foreign materials in surgery is potential erosion into nearby tissues. The endoscopic removal of foreign bodies that have eroded into the urinary tract is a safe and minimally invasive option that has previously been described, most commonly in the bladder and urethra. We present the case of a patient who had a remote history of a pyeloplasty and was found to have different foreign bodies eroding into the ureter causing symptoms. To our knowledge, this is the first case where a patient presented with two different types of ureteral foreign body erosions that were each effectively treated endoscopically. PMID:27579409

  19. Management practices influence productivity of degraded or eroded soils

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Management practices influence the productivity of eroded or degraded soil. This study investigates the influence of beef manure amendment compared with commercial fertil¬izer (urea) applied at two rates (60 and 120 lb N/a) with two tillage practices (conven¬tional tillage, CT, and no-tillage, NT). ...

  20. Management Practices to Improve Productivity of Degraded/Eroded Soils

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Productivity of degraded/eroded soils can be restored by using organic amendment, such as manure, and improved soil management. A study is being conducted near Hays, KS, to investigate and compare restorative potential of two nitrogen (N) sources. Dried beef manure and urea fertilizer were each appl...

  1. Measuring soil erodibility using a laboratory "mini" JET

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Typically the erosion rate of cohesive soils is quantified using an excess shear stress equation, dependent on two major soil parameters: the critical shear stress and the erodibility coefficient. A submerged jet test (JET – Jet Erosion Test) is one method that has been developed for measuring the...

  2. 76 FR 82075 - Highly Erodible Land and Wetland Conservation

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-12-30

    ... effective July 24, 1971 (36 FR 13804), relating to notices of proposed rulemaking and public participation... 3015, subpart V, published in the Federal Register on June 24, 1983 (48 FR 29115). Executive Order... Secretary 7 CFR Part 12 RIN 0560-AH97 Highly Erodible Land and Wetland Conservation AGENCY: Office of...

  3. Quantifying intrinsic and extrinsic factors affecting soil erodibility

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soil erodibility has traditionally been conceived as a soil dependent parameter that can be quantified from intrinsic soil properties that usually stay constant. Development of erosion prediction equations, from the empirical-based Universal Soil Loss Equation (USLE) to a more processed-based Water ...

  4. Bonding stability of adhesive systems to eroded dentin.

    PubMed

    Cruz, Janaina Barros; Bonini, Gabriela; Lenzi, Tathiane Larissa; Imparato, José Carlos Pettorossi; Raggio, Daniela Prócida

    2015-01-01

    This in vitro study evaluated the immediate and 6 months microshear bond strength (µSBS) of different adhesive systems to sound and eroded dentin. Sixty bovine incisors were embedded in acrylic resin and ground to obtain flat buccal dentin surfaces. Specimens were randomly allocated into two groups: sound dentin (immersion in artificial saliva) and eroded dentin (erosive challenge following a pH cycling model comprising 4 ×/day Sprite Light® drink for 10 days). Then, specimens were reassigned according to the adhesive system: etch-and-rinse adhesive (Adper Single Bond), two-step self-etch system (Clearfil SE Bond), or one-step self-etch adhesive (Adper Easy One). Polyethylene tubes with an internal diameter of 0.76 mm were placed over pre-treated dentin and filled with resin composite (Z250). Half of the specimens were evaluated by the µSBS test after 24 h, and the other half 6 months later, after water storage at 37 °C. Failure mode was evaluated using a stereomicroscope (400 ×). Data were analyzed by three-way repeated measures analysis of variance and Tukey's post hoc tests (α = 0.05). After 6 months of water aging, marked reductions in µSBS values were observed, irrespective of the substrate. The µSBS values for eroded dentin were lower than those obtained for sound dentin. No difference in bonding effectiveness was observed among adhesive systems. For all groups, adhesive/mixed failure was observed. In conclusion, eroded dentin compromises the bonding quality of adhesive systems over time. PMID:26154377

  5. Abrasion of eroded root dentine brushed with different toothpastes.

    PubMed

    De Menezes, Márcio; Turssi, Cecilia Pedroso; Hara, Anderson Takeo; Messias, Danielle Cristine Furtado; Serra, Mônica Campos

    2004-09-01

    This study evaluated the surface roughness change and wear provided by different dentifrices on root dentine previously exposed to erosive challenges. According to a randomized complete block design, 150 slabs of bovine root dentine (6 x 3 x 2 mm) were ground flat and polished. In an area of 4 x 3 mm on the dentine surface, specimens were submitted to five erosive/abrasive events, each one composed by: exposure to Sprite Diet or distilled water for 5 min, then to a remineralizing solution for 1 min, and simulation of 5,000 brushing strokes. Four dentifrices--regular (RE), baking soda (BS), whitening (WT) and tartar control (TC)--and distilled water (CO), used as control, were compared. Final texture and the wear depth were evaluated using a profilometer. ANOVA did not show significant interaction, indicating that the effect of dentifrices on both surface roughness change and wear did not depend on whether or not the dentine was eroded ( p>0.05). There was no difference between abrasion of eroded and sound dentine. The Tukey's test revealed that WT, BS and TC provided the highest increase in surface roughness differing from RE and CO. TC yielded the deepest wear of root dentine, whereas RE and CO, the shallowest. No significant difference in wear among BS, TC and WT were observed. Within the limitations of this study, the data showed that abrasion of both eroded and sound root dentine was dependent on the dentifrice used. PMID:15146320

  6. Effects of peptide concentration on remineralization of eroded enamel.

    PubMed

    Chung, Hsiu-Ying; Huang, Kuo-Chen

    2013-12-01

    Promoting remineralization to repair eroded enamel is a promising therapy in clinics. In this study, biocompatible asparagine-serine-serine (NSS) peptide chelates free ions from artificial saliva through charged functional groups, and subsequently form nano-hydroxyapatite crystals to partially repair erosive lesions. The nanomechanical properties, cross-sectional microstructure, types of deposited minerals, and subsurface microstructure of enamel at various treatment stages were characterized by nanoindentation, scanning electron microscopy (SEM), X-ray diffraction (XRD), and transmission electron microscopy (TEM), respectively. The results revealed that the nanohardness and elastic modulus of eroded enamel increase with peptide concentration, particularly for the 3NSS peptide system. In contrast, the structure of the 5NSS peptide is larger and longer, leading to increasing difficulty in penetrating to the deep acid-eroded regions; therefore, the remineralization effect was restricted to the top enamel surface. The 3NSS peptide with high concentration promoted the formation of smaller, finer, and staggered nanohydroxyapatite crystals. The enamel remineralized with a 100μM 3NSS exhibited the highest degree of nanohardness recovery (34%), resulting from subsurface crystalline regrowth.

  7. Photorefractive keratectomy at 193 nm using an erodible mask

    NASA Astrophysics Data System (ADS)

    Gordon, Michael; Brint, Stephen F.; Durrie, Daniel S.; Seiler, Theo; Friedman, Marc D.; Johnsson, N. M. F.; King, Michael C.; Muller, David F.

    1992-08-01

    Clinical experience with more than ten thousand sighted eyes has demonstrated great promise for correcting myopia with photorefractive keratectomy (PRK). Previously reported techniques have incorporated computer-controlled irises, diaphragms, and apertures to regulate the desired distribution of 193 nm radiation onto the eye. This paper reports on an entirely new approach for performing PRK which utilizes an erodible mask to control the shape transfer process. Compared to the more traditional techniques, the erodible mask offers promise of correcting a broad range of refractive errors. In this paper the erodible mask and associated hardware are described in detail. We describe the shape transfer experiments used to predict the functional relationship between the desired refractive correction and the mask shape. We report on early clinical results from five patients with myopic astigmatism. We conclude that the early shape transfer experiments overestimated the spherical component of the correction by 1.25 diopters and underestimated the cylindrical component by approximately 0.85 diopters. The data suggest there may be biological effects which evoke different healing responses when myopic PRK corrections are performed with and without astigmatism. Clinical trials are proceeding with the mask shapes adjusted for these observations.

  8. Sorption and dissipation of aged metolachlor residues in eroded and rehabilitated soils

    Technology Transfer Automated Retrieval System (TEKTRAN)

    To accurately determine availability for offsite transport, sorption and dissipation of aged metolachlor were characterized in rehabilitated and eroded prairie soils using sequential batch slurry and accelerated solvent extraction (ASE). In the eroded upper slope, soil-landscape rehabilitation more ...

  9. 7 CFR 12.20 - NRCS responsibilities regarding highly erodible land.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 1 2013-01-01 2013-01-01 false NRCS responsibilities regarding highly erodible land. 12.20 Section 12.20 Agriculture Office of the Secretary of Agriculture HIGHLY ERODIBLE LAND AND WETLAND CONSERVATION Highly Erodible Land Conservation § 12.20 NRCS responsibilities regarding...

  10. 7 CFR 12.20 - NRCS responsibilities regarding highly erodible land.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 1 2014-01-01 2014-01-01 false NRCS responsibilities regarding highly erodible land. 12.20 Section 12.20 Agriculture Office of the Secretary of Agriculture HIGHLY ERODIBLE LAND AND WETLAND CONSERVATION Highly Erodible Land Conservation § 12.20 NRCS responsibilities regarding...

  11. 7 CFR 760.821 - Compliance with highly erodible land and wetland conservation.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 7 2012-01-01 2012-01-01 false Compliance with highly erodible land and wetland... Disaster Program § 760.821 Compliance with highly erodible land and wetland conservation. (a) The highly erodible land and wetland conservation provisions of part 12 of this title apply to the receipt of...

  12. 7 CFR 760.821 - Compliance with highly erodible land and wetland conservation.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 7 2014-01-01 2014-01-01 false Compliance with highly erodible land and wetland... Disaster Program § 760.821 Compliance with highly erodible land and wetland conservation. (a) The highly erodible land and wetland conservation provisions of part 12 of this title apply to the receipt of...

  13. 7 CFR 760.821 - Compliance with highly erodible land and wetland conservation.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 7 2010-01-01 2010-01-01 false Compliance with highly erodible land and wetland... Disaster Program § 760.821 Compliance with highly erodible land and wetland conservation. (a) The highly erodible land and wetland conservation provisions of part 12 of this title apply to the receipt of...

  14. 7 CFR 760.821 - Compliance with highly erodible land and wetland conservation.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 7 2013-01-01 2013-01-01 false Compliance with highly erodible land and wetland... Disaster Program § 760.821 Compliance with highly erodible land and wetland conservation. (a) The highly erodible land and wetland conservation provisions of part 12 of this title apply to the receipt of...

  15. 7 CFR 760.821 - Compliance with highly erodible land and wetland conservation.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 7 2011-01-01 2011-01-01 false Compliance with highly erodible land and wetland... Disaster Program § 760.821 Compliance with highly erodible land and wetland conservation. (a) The highly erodible land and wetland conservation provisions of part 12 of this title apply to the receipt of...

  16. 7 CFR 12.20 - NRCS responsibilities regarding highly erodible land.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 1 2010-01-01 2010-01-01 false NRCS responsibilities regarding highly erodible land. 12.20 Section 12.20 Agriculture Office of the Secretary of Agriculture HIGHLY ERODIBLE LAND AND WETLAND CONSERVATION Highly Erodible Land Conservation § 12.20 NRCS responsibilities regarding...

  17. 7 CFR 12.20 - NRCS responsibilities regarding highly erodible land.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 1 2012-01-01 2012-01-01 false NRCS responsibilities regarding highly erodible land. 12.20 Section 12.20 Agriculture Office of the Secretary of Agriculture HIGHLY ERODIBLE LAND AND WETLAND CONSERVATION Highly Erodible Land Conservation § 12.20 NRCS responsibilities regarding...

  18. 7 CFR 12.20 - NRCS responsibilities regarding highly erodible land.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 1 2011-01-01 2011-01-01 false NRCS responsibilities regarding highly erodible land. 12.20 Section 12.20 Agriculture Office of the Secretary of Agriculture HIGHLY ERODIBLE LAND AND WETLAND CONSERVATION Highly Erodible Land Conservation § 12.20 NRCS responsibilities regarding...

  19. Site-scale variability of streambank fluvial erodibility parameters as measured with a jet erosion test

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The erosion rate of cohesive streambanks is typically modeled using the excess shear stress equation, dependent on two erodibility parameters: critical shear stress and erodibility coefficient. The Jet Erosion Test (JET) has become the most common method for estimating these erodibility parameters ...

  20. Dynamic replacement and loss of soil carbon on eroding cropland

    USGS Publications Warehouse

    Harden, J.W.; Sharpe, J.M.; Parton, W.J.; Ojima, D.S.; Fries, T.L.; Huntington, T.G.; Dabney, S.M.

    1999-01-01

    Links between erosion/sedimentation history and soil carbon cycling were examined in a highly erosive setting in Mississippi loess soils. We sampled soils on (relatively) undisturbed and cropped hillslopes and measured C, N, 14C, and CO2 flux to characterize carbon storage and dynamics and to parameterize Century and spreadsheet 14C models for different erosion and tillage histories. For this site, where 100 years of intensive cotton cropping were followed by fertilization and contour plowing, there was an initial and dramatic decline in soil carbon content from 1870 to 1950, followed by a dramatic increase in soil carbon. Soil erosion amplifies C loss and recovery: About 100% of the original, prehistoric soil carbon was likely lost over 127 years of intensive land use, but about 30% of that carbon was replaced after 1950. The eroded cropland was therefore a local sink for CO2 since the 1950s. However, a net CO2 sink requires a full accounting of eroded carbon, which in turn requires that decomposition rates in lower slopes or wetlands be reduced to about 20% of the upland value. As a result, erosion may induce unaccounted sinks or sources of CO2, depending on the fate of eroded carbon and its protection from decomposition. For erosion rates typical of the United States, the sink terms may be large enough (1 Gt yr-1, back-of-the-envelope) to warrant a careful accounting of site management, cropping, and fertilization histories, as well as burial rates, for a more meaningful global assessment.

  1. Investigating the Influence of Clay Mineralogy on Stream Bank Erodibility

    NASA Astrophysics Data System (ADS)

    Ambers, R. K.; Stine, M. B.

    2005-12-01

    Soil scientists concerned with erosion of agricultural fields and geotechnical engineers concerned with the mechanical behavior of soils under different conditions have both examined the role of clay mineralogy in controlling soil/sediment properties. Fluvial geomorphologists studying stream channel erosion and stability have focused more on the effects of particle-size distribution, vegetation and rooting. The clay mineralogy of bed and bank sediment has the potential to influence cohesiveness and erodibility, however. The goal of this study is to determine the influence of clay mineralogy on the erodibility of natural stream bank sediment, utilizing techniques drawn from pedology and soil mechanics. Bank samples were collected from eleven sites in small watersheds in central and western Virginia. To obtain sediment containing a range of different clay minerals, watersheds with different types of bedrock were chosen for sampling. Rock types included mafic to felsic metamorphic and igneous rocks, shale, sandstone, and limestone. Where stream bank materials were clearly stratified, different layers were sampled separately. X-ray diffraction of the clay-fraction of the sediment indicates the presence of kaolinite, illite, vermiculite, and mixed-layer clay minerals in various abundances in the different samples. Clay content is 9-46%, as determined by the hydrometer method, and textures range from silty clay and silt loam to clay loam and sandy loam. Organic mater contents range from 1-5% by the loss-on-ignition method. Bulk density of intact sediment samples averages 1.5 g/cc. Liquid limits range from 23-41 with one sample having a value of 65; plasticity indices range from 15-22. While these tests predict that the samples would show a range of mechanical behaviors, the channel morphology at the sampling sites was not strikingly different, all having steep cut banks eroded primarily by scour with no evidence of mass movement and most having a width/depth ratio around

  2. Fates of eroded soil organic carbon: Mississippi Basin case study

    USGS Publications Warehouse

    Smith, S.V.; Sleezer, R.O.; Renwick, W.H.; Buddemeier, R.W.

    2005-01-01

    We have developed a mass balance analysis of organic carbon (OC) across the five major river subsystems of the Mississippi (MS) Basin (an area of 3.2 ?? 106 km2). This largely agricultural landscape undergoes a bulk soil erosion rate of ???480 t??km -2??yr-1 (???1500 ?? 106 t/yr, across the MS Basin), and a soil organic carbon (SOC) erosion rate of ???7 t??km-2??yr-1 (???22 ?? 106 t/yr). Erosion translocates upland SOC to alluvial deposits, water impoundments, and the ocean. Soil erosion is generally considered to be a net source of CO2 release to the atmosphere in global budgets. However, our results indicate that SOC erosion and relocation of soil apparently can reduce the net SOC oxidation rate of the original upland SOC while promoting net replacement of eroded SOC in upland soils that were eroded. Soil erosion at the MS Basin scale is, therefore, a net CO2 sink rather than a source. ?? 2005 by the Ecological Society of America.

  3. Effect of erodent particles on the erosion of metal specimens

    NASA Astrophysics Data System (ADS)

    Razzaque, M. Mahbubur; Alam, M. Khorshed; Khan, M. Ishak

    2016-07-01

    This paper presents the experimental results of the measurement of erosion rate of carbon steel specimens in sand water slurry system in a slurry pot tester. Sylhet sand has been sieved to get three sizes of erodent particles; namely, less than 250 micron, 250 to 590 micron and 590 to 1190 micron. Experiments are done with three sand concentrations (10%, 15% and 20%). The rate of erosion of the carbon steel specimens is measured as the loss of weight per unit surface area per unit time under the dynamic action of solid particles. The eroded surfaces of the specimens are examined using Scanning Electron Microscopy (SEM) to visualize the impact of the slurry of various conditions. It is seen that irrespective of the particle size the rate of erosion increases with the increase of slurry concentration. This increment of erosion rate at high concentration is high for large particles. High erosion rate is observed in case of large sand particles. In case of small and fine particles erosion rate is small because of low impact energy as well as the wastage of energy to overcome the hindrance of the finer particles before striking on the specimen surface.

  4. Biologically erodable microspheres as potential oral drug delivery systems

    NASA Astrophysics Data System (ADS)

    Mathiowitz, Edith; Jacob, Jules S.; Jong, Yong S.; Carino, Gerardo P.; Chickering, Donald E.; Chaturvedi, Pravin; Santos, Camilla A.; Vijayaraghavan, Kavita; Montgomery, Sean; Bassett, Michael; Morrell, Craig

    1997-03-01

    Biologically adhesive delivery systems offer important advantages1-5 over conventional drug delivery systems6. Here we show that engineered polymer microspheres made of biologically erodable polymers, which display strong adhesive interactions with gastrointestinal mucus and cellular linings, can traverse both the mucosal absorptive epithelium and the follicle-associated epithelium covering the lymphoid tissue of Peyer's patches. The polymers maintain contact with intestinal epithelium for extended periods of time and actually penetrate it, through and between cells. Thus, once loaded with compounds of pharmacological interest, the microspheres could be developed as delivery systems to transfer biologically active molecules to the circulation. We show that these microspheres increase the absorption of three model substances of widely different molecular size: dicumarol, insulin and plasmid DNA.

  5. Analysis of eroded bovine teeth through laser speckle imaging

    NASA Astrophysics Data System (ADS)

    Koshoji, Nelson H.; Bussadori, Sandra K.; Bortoletto, Carolina C.; Oliveira, Marcelo T.; Prates, Renato A.; Deana, Alessandro M.

    2015-02-01

    Dental erosion is a non-carious lesion that causes progressive tooth wear of structure through chemical processes that do not involve bacterial action. Its origin is related to eating habits or systemic diseases involving tooth contact with substances that pose a very low pH. This work demonstrates a new methodology to quantify the erosion by coherent light scattering of tooth surface. This technique shows a correlation between acid etch duration and laser speckle contrast map (LASCA). The experimental groups presented a relative contrast between eroded and sound tissue of 17.8(45)%, 23.4 (68)% 39.2 (40)% and 44.3 (30)%, for 10 min, 20 min, 30 min and 40 min of acid etching, respectively.

  6. Effects of erodant particle shape and various heat treatments on erosion resistance of plain carbon steel

    NASA Technical Reports Server (NTRS)

    Salik, J.; Buckley, D. H.

    1981-01-01

    Erosion tests were conducted on 1045 steel samples which had been subjected to different heat treatments. The weight of material removed upon erosion with glass beads and crushed glass was measured. The data show that there is no correlation between hardness and erosion resistance. The erosion rate was strongly dependent on the shape of erodant particles, being an order of magnitude higher for erosion with crushed glass than with glass beads. Heat treatment had a profound effect on the erosion resistance when the erodant particles were glass beads but little or no effect when the particles were crushed glass. It is thus concluded that different mechanisms of material removal are involved with these two erodants. This conclusion is supported by the surface morphology of annealed 1045 steel samples which had been eroded by these two types of erodant particles. SEM micrographs of the eroded surfaces show that for erosion with glass beads it is deformation induced fracture of surface layers.

  7. Cytochrome P450 responses and PCB congeners in pipping heron embryos from Virginia, the Great Lakes and San Francisco Bay

    USGS Publications Warehouse

    Rattner, B.A.; Melancon, M.J.; Custer, T.W.; Tillett, D.E.; Woodin, Bruce R.; Stegeman, John J.

    1992-01-01

    Pipping black-crowned night-heron (Nvcticorax nvcticorax) embryos were collected from undisturbed (Chincoteague National Wildlife Refuge VA; CNWR) and industrialized (Cat Island, Green Bay WI and San Francisco Bay, CA; SFB) locations. Hepatic monooxygenases (AHH, EROD, BROD, ECOD) were induced up to 100-fold, and were correlated (r=0.50 to 0.72) with total PCB burdens (N =61 embryos). A subset of 30 embryos have now been analyzed by GC/MS for 12 AHH-active PCB congeners and by Western blot for cytochromes P450lA and P450llB. At Cat Island, concentrations of 8 congeners were greater (P <0.05) than at CNWR. P450lA and P450llB were detected in 44% and 100% of the Cat Island embryos compared to 8% and 33% of the CNWR + SFB embryos. Cytochrome P450 parameters were correlated with the total PCBs (r =0.44 to 0.67) and with at least 9 PCB congeners (r =0.39 to 0.77). Since P450 responses might be affected by other contaminants, sample extract potency in the H411E rat hepatoma bioassay is being determined to study relationships among dioxin equivalents and cytochrome P450 parameters.

  8. Differential effects of biochar on soils within an eroded field

    NASA Astrophysics Data System (ADS)

    Schumacher, Thomas; Chintala, Rajesh; Sandhu, Saroop; Kumar, Sandeep; Clay, Dave; Gelderman, Ron; Papiernik, Sharon; Malo, Douglas; Clay, Sharon; Julson, Jim

    2015-04-01

    Future uses of biochar will in part be dependent not only on the effects of biochar on soil processes but also on the availability and economics of biochar production. If pyrolysis for production of bio-oil and syngas becomes wide-spread, biochar as a by-product of bio-oil production will be widely available and relatively inexpensive compared to the production of biochar as primary product. Biochar produced as a by-product of optimized bio-oil production using regionally available feedstocks was examined for properties and for use as an amendment targeted to contrasting soils within an eroded field in an on-farm study initiated in 2013 at Brookings, South Dakota, USA. Three plant based biochar materials produced from carbon optimized gasification of corn stover (Zea mays L.), Ponderosa pine (Pinus ponderosa Lawson and C. Lawson) wood residue, and switchgrass (Panicum virgatum L.) were applied at a 1% (w/w) rate to a Maddock soil (Sandy, Mixed, Frigid Entic Hapludolls) located in an eroded upper landscape position and a Brookings soil (Fine-Silty, Mixed, Superactive, Frigid Pachic Hapludolls) located in a depositional landscape position. The cropping system within this agricultural landscape was a corn (Zea mays L.) and soybean (Glycine max L.) rotation. Biochar physical and chemical properties for each of the feedstocks were determined including pH, surface area, surface charge potential, C-distribution, ash content, macro and micro nutrient composition. Yields, nutrient content, and carbon isotope ratio measurements were made on the harvested seed. Soil physical properties measured included water retention, bulk density, and water infiltration from a ponded double ring infiltrometer. Laboratory studies were conducted to determine the effects of biochar on partitioning of nitrate and phosphorus at soil surface exchange complex and the extracellular enzymes activity of C and N cycles. Crop yields were increased only in the Maddock soil. Biochar interacted with each

  9. Context of Carbonate Rocks in Heavily Eroded Martian Terrain

    NASA Technical Reports Server (NTRS)

    2008-01-01

    The color coding on this composite image of an area about 20 kilometers (12 miles) wide on Mars is based on infrared spectral information interpreted as evidence of various minerals present. Carbonate, which is indicative of a wet and non-acidic history, occurs in very small patches of exposed rock appearing green in this color representation, such as near the lower right corner.

    The scene is heavily eroded terrain to the west of a small canyon in the Nili Fossae region of Mars. It was one of the first areas where researchers on the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) science team detected carbonate in Mars rocks. The spectral information comes from infrared imaging by CRISM, one of six science instruments on NASA's Mars Reconnaissance Orbiter. That coloring is overlaid on a grayscale image from the same orbiter's Context Camera.

    The uppermost capping rock unit (purple) is underlain successively by banded olivine-bearing rocks (yellow) and rocks bearing iron-magnesium smectite clay (blue). Where the olivine is a greenish hue, it has been partially altered by interaction with water. The carbonate and olivine occupy the same level in the stratigraphy, and it is thought that the carbonate formed by aqueous alteration of olivine. The channel running from upper left to lower right through the image and eroding into the layers of bedrock testifies to the past presence of water in this region. That some of the channels are closely associated with carbonate (lower right) indicates that waters interacting with the carbonate were neutral to alkaline because acidic waters would have dissolved the carbonate.

    Information for the color coding came from CRISM images catalogued as FRT0000B438, FRT0000A4FC, and FRT00003E12. This composite was made using 2.38-micrometer-wavelenghth data as red, 1.80 micrometer as green and 1.15 micrometer as blue.

    The base black-and-white image, acquired at a resolution of 5 meters (16 feet) per

  10. Modeling sediment delivery from a highly erodible mountain catchment

    NASA Astrophysics Data System (ADS)

    Le Bouteiller, C.; Asif, N. M.; Recking, A.; Liebault, F.

    2015-12-01

    Draix observatory is located in the French Alps on a highly erodible substrate of shale. Most of the observatory is in a badland area characterized by steep gullies and high erosion rates (up to 1cm/year). Within the observatory, the study focuses on the Moulin, which is an 8ha catchment located at an elevation of 850-925m, with 54% of badland area. Available data includes DEM, meteorological data, high-frequency records of discharge and suspended sediment concentration during the floods, cumulative values of bedload transport for each flood, high-frequency records of bedload transport for a few events from a Birkbeck sampler. Modeling sediment delivery in such a catchment is challenging because 1) most available models have been designed for low-relief regions and do not account for steep slope processes such as debris flow and landslides; 2) hydrology (especially flashfloods) in mountainous regions is not well understood; 3) soil properties are very heterogeneous ; 4) multiple time scales are involved: seasonal sediment production on the slopes, storage in the bed and exportation requires to work on yearly times scales, while summer floods and most sediment delivery events occur over a few minutes only. We evaluate the ability of the SHETRAN model to reproduce sediment delivery patterns from the catchment. First, we calibrate the hydrological model using one year of meteorological and hydrological data. We then apply the sediment transport module over several flood events, using in-situ measurements of bed and slope grain-size distributions. Finally we investigate how sediment available on the slopes moves through the catchment over a year. Event-scale volumes of sediment simulated by the model are comparable to observed values within an order of 2. Sediment delivery rates are very sensitive to the slope grain-size distribution. Depending on sediment availability on the slopes and on soil erodibility, the catchment is running either in a supply-limited or

  11. Sculpting of an erodible body by flowing water.

    PubMed

    Ristroph, Leif; Moore, Matthew N J; Childress, Stephen; Shelley, Michael J; Zhang, Jun

    2012-11-27

    Erosion by flowing fluids carves striking landforms on Earth and also provides important clues to the past and present environments of other worlds. In these processes, solid boundaries both influence and are shaped by the surrounding fluid, but the emergence of morphology as a result of this interaction is not well understood. We study the coevolution of shape and flow in the context of erodible bodies molded from clay and immersed in a fast, unidirectional water flow. Although commonly viewed as a smoothing process, we find that erosion sculpts pointed and cornerlike features that persist as the solid shrinks. We explain these observations using flow visualization and a fluid mechanical model in which the surface shear stress dictates the rate of material removal. Experiments and simulations show that this interaction ultimately leads to self-similarly receding boundaries and a unique front surface characterized by nearly uniform shear stress. This tendency toward conformity of stress offers a principle for understanding erosion in more complex geometries and flows, such as those present in nature. PMID:23150552

  12. Eroding students' rural motivation: first do no harm?

    PubMed

    Hurst, Samia

    2014-01-01

    Migration of health professionals is one of the drivers of vast inequalities in access to healthcare, as medical graduates tend to move away from both poorer countries and rural areas. One of the central ethical problems raised in attempting to alleviate these inequalities is the tension between the healthcare needs of under-served patients and the rights of medical graduates to choose their place of work and specialty. If medical graduates had greater motivation to work in under-served rural areas, this tension would decrease accordingly. Medical schools have a duty to avoid eroding existing motivation for such training and practice. This duty has practical implications. Medical students' motivation regarding their choice of specialty changes during medical training, turning them away from choices such as primary care and rural practice towards more highly specialised, more hospital based specialties. Although students may be victims of a number of biases in the initial assessment, this is unlikely to be the whole story. Students' priorities are likely to change based on their admiration for specialist role models and the visibility of the financial and non-financial rewards attached to these specialties. Students may also have a false expectation upon admission that they will be proficient in rural medicine on graduation, and change their mind once they realise the limits of their skills in that area. Although the measures required to reverse this effect currently lack a solid evidence base, they are plausible and supported by the available data.

  13. Sculpting of an erodible body by flowing water

    PubMed Central

    Ristroph, Leif; Moore, Matthew N. J.; Childress, Stephen; Shelley, Michael J.; Zhang, Jun

    2012-01-01

    Erosion by flowing fluids carves striking landforms on Earth and also provides important clues to the past and present environments of other worlds. In these processes, solid boundaries both influence and are shaped by the surrounding fluid, but the emergence of morphology as a result of this interaction is not well understood. We study the coevolution of shape and flow in the context of erodible bodies molded from clay and immersed in a fast, unidirectional water flow. Although commonly viewed as a smoothing process, we find that erosion sculpts pointed and cornerlike features that persist as the solid shrinks. We explain these observations using flow visualization and a fluid mechanical model in which the surface shear stress dictates the rate of material removal. Experiments and simulations show that this interaction ultimately leads to self-similarly receding boundaries and a unique front surface characterized by nearly uniform shear stress. This tendency toward conformity of stress offers a principle for understanding erosion in more complex geometries and flows, such as those present in nature. PMID:23150552

  14. Soil wind erodibility based on dry aggregate-size distribution in the Tarim Basin

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Tarim Basin is an important source of airborne particulate matter that contributes to poor air quality in China. However, little attention has been given to estimating wind erodibility of soils in the region. The objective of this study was to determine the soil wind erodibility for six land use...

  15. Value-Eroding Teacher Behaviors Scale: A Validity and Reliability Study

    ERIC Educational Resources Information Center

    Arseven, Zeynep; Kiliç, Abdurrahman; Sahin, Seyma

    2016-01-01

    In the present study, it is aimed to develop a valid and reliable scale for determining value-eroding behaviors of teachers, hence their values of judgment. The items of the "Value-eroding Teacher Behaviors Scale" were designed in the form of 5-point likert type rating scale. The exploratory factor analysis (EFA) was conducted to…

  16. Developing soil erodibility prediction equations for the Rangeland Hydrology and Erosion Model (RHEM)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soil erodibility is a key factor for estimating soil erosion using physically based models. In this study, a new parameterization approach for estimating erodibility was developed for the Rangeland Hydrology and Erosion Model (RHEM). The approach uses empirical equations that were developed by apply...

  17. Erodibility of selected soils and estimates of sediment yields in the San Juan Basin, New Mexico

    USGS Publications Warehouse

    Summer, Rebecca M.

    1981-01-01

    Onsite rainfall-simulation experiments were conducted to derive field-erodibility indexes for rangeland soils and soils disturbed by mining in coal fields of northwestern New Mexico. Mean indexes on rangeland soils range from 0 grams (of detached soil) on dune soil to 121 grams on wash-transport zones. Mean field-erodibility-index values of soils disturbed by mining range from 16 to 32 grams; they can be extrapolted to nearby coal fields where future mining is expected. Because field-erodibility-index data allow differentiation of erodibilities across a variable landscape, these indexes were used to adjust values of K, the erodibility factor of the Universal Soil Loss Equation. Estimates of soil loss and sediment yield were then calculated for a small basin following mining. (USGS)

  18. Stage-dependent ethoxyresorufin-O-deethylase (EROD) in vivo activity in medaka (Oryzias latipes) embryos.

    PubMed

    González-Doncel, Miguel; Carbonell, Gregoria; San Segundo, Laura; Sastre, Salvador; Beltrán, Eulalia M; Fernández-Torija, Carlos

    2015-09-01

    Using medaka (Oryzias latipes) embryos, this study aimed to quantitatively characterize the stage-dependent in vivo ethoxyresorufin-O-deethylase (EROD) as indicator of cytochrome P4501A (CYP1A) activity. Embryos were challenged for 24-h to an agonist (β-naphthoflavone [BNF], 2.5, 5, 10, and 20 μg L(-1)) or to its combination (2.5 μg L(-1)) with an antagonist (α-naphthoflavone [ANF], 25, 50, 100, and 200 μg L(-1)), initiated at four different developmental time points (1, 3, 6, and 9 d post-fertilization [dpf]). Respective induction and competitive inhibition were evaluated over fluorescent images of whole embryo (nonorgan-specific [NOS] EROD activity) and gallbladder (organ-specific [OS] EROD activity). Both flavonoids showed signs of stability in solution. Generally speaking, the mean fluorescence intensity (MFI) values for NOS EROD increased with BNF concentration and exposure challenge. BNF co-exposure with ⩾50 μg ANF L(-1) during the 1-2 and 3-4 dpf challenges lowered NOS EROD to undetectably induced levels. Significant increments in MFIs for OS-EROD were seen from exposures to ⩾2.5 μg BNF L(-1), peaking during the 6-7 dpf challenge regardless of BNF concentration. The simultaneous BNF/ANF incubation showed competitive inhibition for OS EROD activity, although levels were generally detectably induced during all challenges and at all ANF concentrations. The morphometric in vivo gallbladder analysis indicated significant dilation in the 10 dpf-old embryos co-exposed to BNF and 200 μg ANF L(-1). This quantitative approach can be used successfully at 4 dpf at the NOS-EROD or OS-EROD levels, although the NOS-EROD response was sensitive enough to induction or inhibition, even at 2 dpf.

  19. A Comparison of Thresholds: Shields and Erodibility Index

    NASA Astrophysics Data System (ADS)

    Humphries, R. P.; Annandale, G. W.; Rock, A. J.

    2015-12-01

    The threshold between stasis and mobility, and the forms and processes associated with the interfacial instabilities it defines, is a fundamental component of most morphodynamic systems. Scientists and engineers who focus on the interface of the earth's dynamic surface and the turbulent fluids of the atmosphere and hydrosphere, have approached this interface from a diversity of perspectives. In the field of sediment transport, Shield's 1936 paper stands as a benchmark for the theoretical understanding of the threshold of incipient motion of non-cohesive granular transport. However, in processes such as the erosion of cohesive material or bedrock erosion, consensus has yet to be reached among researchers, as to which method most aptly encompasses these processes. The lack of consensus is reasonable, considering the diversity of the applications, and implications, of interface dynamics. When thresholds may depend on the sequence of antecedent conditions, as in cohesive sediment entrainment, or the time scale of perception ranges from many Hertz to geologic eras, as in the processes of rock scour, a diversity of conceptual models is to be anticipated. In Scour Technology (Annandale 2006), the Erodibility Index Method (EIM) is presented as a threshold paradigm that spans the breadth of all earth materials that may experiences erosion by fluid forces. The authors present a comparison of the modern expression of the benchmark theoretical understanding of the threshold of incipient motion of non-cohesive granular material with the EIM. Results illustrate that each threshold can provide insight into the other and that the Shields parameter can be expressed within the vocabulary of the EIM.

  20. Relationship between soil erodibility and modeled infiltration rate in different soils

    NASA Astrophysics Data System (ADS)

    Wang, Guoqiang; Fang, Qingqing; Wu, Binbin; Yang, Huicai; Xu, Zongxue

    2015-09-01

    The relationship between soil erodibility, which is hard to measure, and modeled infiltration rate were rarely researched. Here, the soil erodibility factors (K and Ke in the USLE, Ki and K1 in the WEPP) were calculated and the infiltration rates were modeled based on the designed laboratory simulation experiments and proposed infiltration model, in order to build their relationship. The impacts of compost amendment on the soil erosion characteristics and relationship were also studied. Two contrasting agricultural soils (bare and cultivated fluvo-aquic soils) were used, and different poultry compost contents (control, low and high) were applied to both soils. The results indicated that the runoff rate, sediment yield rate and soil erodibility of the bare soil treatments were generally higher than those of the corresponding cultivated soil treatments. The application of composts generally decreased sediment yield and soil erodibility but did not always decrease runoff. The comparison of measured and modeled infiltration rates indicated that the model represented the infiltration processes well with an N-S coefficient of 0.84 for overall treatments. Significant negative logarithmic correlations have been found between final infiltration rate (FIR) and the four soil erodibility factors, and the relationship between USLE-K and FIR demonstrated the best correlation. The application of poultry composts would not influence the logarithmic relationship between FIR and soil erodibility. Our study provided a useful tool to estimate soil erodibility.

  1. Leopard frog PCB levels and evaluation of EROD as a biomarker in Green Bay ecosystem

    SciTech Connect

    Huang, Y.W.; Karasov, W.H.; Patnode, K.P.

    1995-12-31

    The induction of mixed function oxidases has been shown to be a promising biomarker in many taxa of wildlife, though not yet tested for amphibians. The three hypotheses tested in this study were (1) activities of hepatic EROD of leopard frog (Rana pipiens) are induced following exposure to planar chlorinated PCBs, (2) tissue PCB residue levels of leopard frogs are positively correlated with their wetland sediment PCB levels, and (3) EROD activities are positively correlated with tissue PCB concentrations and sediment PCB. In the laboratory, EROD was increased 2--3 times seven days after i.p. injection with PCB 126 at doses {ge} 2.3 ppm (wet mass basis). Leopard frogs from seven sites along the Lower Fox River and Green Bay in 1994--1995 were assayed for hepatic EROD activities and total PCB levels in carcasses. Tissue PCB levels ranged from 3 to 152 ppb (including coplanar congeners) and were highest from sites with higher sediment PCB. EROD activity in frogs collected in August--September was not significantly correlated with frog body mass and was similar among sites with one exception. There was no significant correlation between EROD activity and tissue PCB concentration. This result was consistent with the fact that the frogs collected from the Green Bay ecosystem had relatively low PCB levels compared with what was required for induction in the laboratory. The authors conclude that EROD activity is not a sensitive biomarker of PCB exposure in leopard frogs in this ecosystem.

  2. A new method to determine eroded areas in arid environment using Landsat satellite imagery

    NASA Astrophysics Data System (ADS)

    A, Aydda; Ah, Algouti; Ab, Algouti; M, Essemani; Y, Taghya

    2014-06-01

    Erosion (by water or wind) is an increasing problem for many local authorities and government agencies throughout the world. The identification of eroded areas in arid and humid regions can be very useful for environmental planning and can help reduce soil and sediment degradation in these regions. In this work we present a new method to determine eroded areas in arid environment. In this method were explored lithological data to determine eroded areas. These data were collected in the field using GPS (Global Positioning System) checkpoints and geological maps. For that, two lithological maps of the study areas were analysed to determine lithological data change. Those two maps were obtained from the classification algorithm by applying the maximum likelihood on two Landsat satellite images. After images classification and validation a change detection technique was adopted to determine eroded areas. This method was applied in northern part of Atlantic Sahara desert to confirm their potentiality.

  3. Soil erodibility in Europe: a high-resolution dataset based on LUCAS.

    PubMed

    Panagos, Panos; Meusburger, Katrin; Ballabio, Cristiano; Borrelli, Pasqualle; Alewell, Christine

    2014-05-01

    The greatest obstacle to soil erosion modelling at larger spatial scales is the lack of data on soil characteristics. One key parameter for modelling soil erosion is the soil erodibility, expressed as the K-factor in the widely used soil erosion model, the Universal Soil Loss Equation (USLE) and its revised version (RUSLE). The K-factor, which expresses the susceptibility of a soil to erode, is related to soil properties such as organic matter content, soil texture, soil structure and permeability. With the Land Use/Cover Area frame Survey (LUCAS) soil survey in 2009 a pan-European soil dataset is available for the first time, consisting of around 20,000 points across 25 Member States of the European Union. The aim of this study is the generation of a harmonised high-resolution soil erodibility map (with a grid cell size of 500 m) for the 25 EU Member States. Soil erodibility was calculated for the LUCAS survey points using the nomograph of Wischmeier and Smith (1978). A Cubist regression model was applied to correlate spatial data such as latitude, longitude, remotely sensed and terrain features in order to develop a high-resolution soil erodibility map. The mean K-factor for Europe was estimated at 0.032 thahha(-1)MJ(-1)mm(-1) with a standard deviation of 0.009 thahha(-1)MJ(-1)mm(-1). The yielded soil erodibility dataset compared well with the published local and regional soil erodibility data. However, the incorporation of the protective effect of surface stone cover, which is usually not considered for the soil erodibility calculations, resulted in an average 15% decrease of the K-factor. The exclusion of this effect in K-factor calculations is likely to result in an overestimation of soil erosion, particularly for the Mediterranean countries, where highest percentages of surface stone cover were observed.

  4. Role of soil erodibility in affecting available nitrogen and phosphorus losses under simulated rainfall

    NASA Astrophysics Data System (ADS)

    Wang, Guoqiang; Wu, Binbin; Zhang, Lei; Jiang, Hong; Xu, Zongxue

    2014-06-01

    The loss of available nutrients and the effects of soil erodibility on available nutrients losses were rarely researched. Here, laboratory simulation experiments were conducted to determine the soil erodibility effects on the available nitrogen (AN) and phosphorus (AP) losses. The impacts of rainfall intensity and slope on AN and AP losses were also studied. Two contrasting agricultural soils (Burozems and Cinnamon) that occur throughout the northern erosion region of China were selected. Two rainfall intensities (60 and 120 mm h-1) and two slopes (10% and 20%) were studied. Overall, greater runoff, sediment and available nutrient losses occurred from the Cinnamon soil due to its greater soil erodibility, which was approximately 2.8 times greater than that of the Burozems soil. The influence of runoff on sediment was positively linear. The absolute slope of the regression line between runoff rate and sediment yield rate was suitable as a soil erodibility indicator. Runoff-associated AN and AP losses were mainly controlled by runoff rate, and were weakly affected by soil erodibility (p > 0.05). However, soil erodibility significantly influenced the sediment-associated AN and AP losses (p < 0.01), and a positive logarithmic correlation best described their relationships. Since the runoff-associated AN and AP losses dominated the total AN and AP losses for both soils, soil erodibility also exhibited negligible influence on the total AN and AP losses (p > 0.05). Increasing rainfall intensity and slope generally increased the runoff, sediment, and available nutrient losses for both soils, but had no significant influences on their relationships. Our results provide a better understanding of soil and nutrient loss mechanisms.

  5. Six month EROD response pattern of dioxin-fed brook trout

    SciTech Connect

    Daniel, F.B.; Cormier, S.; Subramanian, B.; Williams, D.; Torsella, J.; Lech, J.

    1994-12-31

    Brook trout, Salvelinus fontinalis, were fed tritiated-labeled 2,3,7,8-TCDD in two phases, a 5-week loading phase beginning in early July, followed by a maintenance phase lasting until middle October. The loading phase brought the trout to the desired whole-body TCDD concentration. The maintenance phase held the whole-body TCDD level constant during growth and deputation through mid-October. Six treatment groups were defined by the following whole-body TCDD concentrations: 0.0, 75, 150, 300, 600, and 120 pg/g. Hepatic EROD activity was measured fluorometrically at two to three week intervals from July, 1993 through October 1993 and once in January, 1994. In the two highest treatment groups, both males and females had significantly elevated levels of EROD activity and responded in a dose-response fashion. The EROD values for males were significantly higher than for females and their seasonal response patterns were different. For males, the maximum EROD response was maintained from July through January. For females, EROD was elevated from July through September, declined and then increased to the highest levels in January. Results were confirmed by immunoassay of selected microsomes samples for CY1A1 with the specific antipeptide antibody, anti-trout CYP1A1{sup 277-294/KLH} using Western Blots and densitometry to detect any losses in catalytic activity. these data demonstrate the complexity of the EROD response of brook trout to dioxin and suggest that physiological conditions associated with reproduction might affect the EROD response.

  6. Seabed erodibility variations on the Louisiana continental shelf before and after the 2011 Mississippi River flood

    NASA Astrophysics Data System (ADS)

    Xu, K.; Corbett, D. R.; Walsh, J. P.; Young, D.; Briggs, K. B.; Cartwright, G. M.; Friedrichs, C. T.; Harris, C. K.; Mickey, R. C.; Mitra, S.

    2014-08-01

    Erodibility is critical to the sediment resuspension process but has not been measured systematically in large river-dominated muddy continental shelves before. During early summer of 2011, the Mississippi River experienced a major flood event. This flood provided a unique opportunity to examine how shelf seabed erodibility responded to a large river flood, and the ultimate fate of flood deposition is important to geological and biogeochemical processes (e.g., stratal formation, carbon sequestration). A total of 106 sediment cores were collected on the Louisiana shelf during five cruises in 2010 and 2011, and a new dataset was used to evaluate the response of the seabed to the recent conditions. The localized flood deposit was mainly within tens of kilometers of river sources, and little sediment accumulated on the middle Louisiana shelf. Seabed erodibility was measured using a dual-core Gust Erosion Microcosm System. The erodibility of sediment collected in April 2011 exceeded that for August 2010 and August 2011. The springtime increase in erodibility seemed to be related to the recent presence of energetic waves that mobilized the seabed. Erodibility was highest on the inner shelf southwest of Atchafalaya Bay, intermediate on the middle shelf, lowest in the Mississippi Canyon, and highly variable on the Mississippi subaqueous delta. These spatial patterns were influenced by proximity to river sources, flood-deposit thicknesses, intensity of wave-driven bed stresses, and bioturbation. The flood-deposit thickness itself, however, was not sufficient to explain all the spatial variations of erodibility after the peak of the Mississippi flood. Comparing values to published data, the depth-varying erodibility on the Louisiana shelf was close to the "low erodibility" level for the York River of Virginia, and similar to the data collected from Baltimore Harbor in Maryland and the main stem of upper Chesapeake Bay. Our findings promote understanding of the resuspension

  7. Hypothetical Reentry Thermostructural Performance of Space Shuttle Orbiter With Missing or Eroded Thermal Protection Tiles

    NASA Technical Reports Server (NTRS)

    Ko, William L.; Gong, Leslie; Quinn, Robert D.

    2004-01-01

    This report deals with hypothetical reentry thermostructural performance of the Space Shuttle orbiter with missing or eroded thermal protection system (TPS) tiles. The original STS-5 heating (normal transition at 1100 sec) and the modified STS-5 heating (premature transition at 800 sec) were used as reentry heat inputs. The TPS missing or eroded site is assumed to be located at the center or corner (spar-rib juncture) of the lower surface of wing midspan bay 3. For cases of missing TPS tiles, under the original STS-5 heating, the orbiter can afford to lose only one TPS tile at the center or two TPS tiles at the corner (spar-rib juncture) of the lower surface of wing midspan bay 3. Under modified STS-5 heating, the orbiter cannot afford to lose even one TPS tile at the center or at the corner of the lower surface of wing midspan bay 3. For cases of eroded TPS tiles, the aluminum skin temperature rises relatively slowly with the decreasing thickness of the eroded central or corner TPS tile until most of the TPS tile is eroded away, and then increases exponentially toward the missing tile case.

  8. Improvement of the optical transmission of an eroded soda lime glass by PVB and PES coatings

    NASA Astrophysics Data System (ADS)

    Bouaouadja, N.; Bousbaa, C.; Mahdaoui, T.; Laouamri, H.; Madjoubi, M. A.

    2009-11-01

    The aim of this work is to improve the optical transmission of a soda lime glass eroded by sandblasting by using polyvinyl butyrate (PVB) and polyester (PES) coatings. Various damage states were obtained in laboratory by varying the projected erodent sand mass (Mp=10-200 g). Transparent layers of PVB and PES were deposited on damaged surfaces. Uncoated eroded glass samples have their optical transmission T strongly deteriorated with the increase of sand mass. It decreases to 27% for a mass of 200 g. The use of the PVB and PES coatings on damaged surface ameliorate substantially the optical transmission. For the extreme case (Mp=200 g), the two deposited layers improve respectively to 87% and 81% with the PVB and the PES films. After a subsequent sandblasting damage on the covered glasses, the evaluation of the optical transmission shows that it only decreases to intermediate values (57% for PVB and 50% for PES).

  9. Implementation of the century ecosystem model for an eroding hillslope in Mississippi

    USGS Publications Warehouse

    Sharpe, Jodie; Harden, Jennifer W.; Dabney, Seth M.; Ojima, Dennis; Parton, William

    1998-01-01

    The objective of this study was to parameterize and implement the Century ecosystem model for an eroding, cultivated site near Senatobia, in Panola County, Mississippi, in order to understand the loss and replacement of soil organic carbon on an eroding cropland. The sites chosen for this study are located on highly eroded loess soils where USDA has conducted studies on rates of soil erosion. We used USDA sediment data from the study site and historical erosion estimates from the nearby area as model input for soil loss; in addition, inputs for parametization include particle-size data, climate data, and rainfall/runoff data that were collected and reported in companion papers. A cropping scenario was implemented to simulate a research site at the USDA watershed 2 at the Nelson Farm. Model output was compiled for comparison with data collected and reported in companion reports; interpretive comparisons are reported in Harden et al, in press.

  10. Mapping Eroded Areas on Mountain Grassland with Terrestrial Photogrammetry and Object-Based Image Analysis

    NASA Astrophysics Data System (ADS)

    Mayr, Andreas; Rutzinger, Martin; Bremer, Magnus; Geitner, Clemens

    2016-06-01

    In the Alps as well as in other mountain regions steep grassland is frequently affected by shallow erosion. Often small landslides or snow movements displace the vegetation together with soil and/or unconsolidated material. This results in bare earth surface patches within the grass covered slope. Close-range and remote sensing techniques are promising for both mapping and monitoring these eroded areas. This is essential for a better geomorphological process understanding, to assess past and recent developments, and to plan mitigation measures. Recent developments in image matching techniques make it feasible to produce high resolution orthophotos and digital elevation models from terrestrial oblique images. In this paper we propose to delineate the boundary of eroded areas for selected scenes of a study area, using close-range photogrammetric data. Striving for an efficient, objective and reproducible workflow for this task, we developed an approach for automated classification of the scenes into the classes grass and eroded. We propose an object-based image analysis (OBIA) workflow which consists of image segmentation and automated threshold selection for classification using the Excess Green Vegetation Index (ExG). The automated workflow is tested with ten different scenes. Compared to a manual classification, grass and eroded areas are classified with an overall accuracy between 90.7% and 95.5%, depending on the scene. The methods proved to be insensitive to differences in illumination of the scenes and greenness of the grass. The proposed workflow reduces user interaction and is transferable to other study areas. We conclude that close-range photogrammetry is a valuable low-cost tool for mapping this type of eroded areas in the field with a high level of detail and quality. In future, the output will be used as ground truth for an area-wide mapping of eroded areas in coarser resolution aerial orthophotos acquired at the same time.

  11. Erodibility of arable soils in Georgia during the period of storm runoff

    NASA Astrophysics Data System (ADS)

    Gogichaishvili, G. P.

    2012-02-01

    The erodibility of arable soils in Georgia varies from 1.0 to 2.9 t/ha per unit of the rainfall erosivity index. The well-structured brown forest and yellow-brown soils with a high humus content are the most resistant to erosion. The soils in the dry areas of Georgia (gray-cinnamon and cinnamon soils) are the most susceptible to erosion. The first map of the soil erodibility was composed that illustrates the spatial distribution pattern of this parameter in the Georgia territory.

  12. Erodibility controls on the vertical and horizontal scalings of topography : a case study in the Himalayas

    NASA Astrophysics Data System (ADS)

    Godard, V.; Steer, P.

    2011-12-01

    Understanding the scaling properties of topography in actively uplifting areas is a major issue in quantitative geomorphology. Analytical formulations of non-glaciated landscape evolution clearly demonstrate that metrics such as local relief or drainage density are explicitly related to the spatial distribution of tectonic uplift, precipitation, erodibility and local slope across the landscape. However, in most regions, these parameters are seldom documented with enough resolution and precision to allow a systematic and statistically significant investigation of their relationships with both horizontal and vertical scaling properties of topography. A notable exception is the Himalaya of central Nepal, where the last 20 years of tectonic and geomorphological research have produced one of the densest regional data-set and documented major gradients in uplift and precipitation across the range [e.g. Lavé and Avouac, 2001; Bookhagen and Burbank, 2006]. The purpose of our study is to use this data in order to develop a detailed investigation of the influence of the erodibility parameter in controlling the structure and texture of the landscape. We first build on the derivation of total catchment relief of Tucker and Whipple [2002] to include the contribution of precipitation in addition to uplift, erodibility. Then, by minimizing the misfit between observed and predicted catchment relief, we assess the erodibility parameter for each second or third order catchment in our area of investigation. The resultant erodibility map (1) matches the distribution of geological units and (2) reveals a number of interesting second order patterns, such as along-strike fluctuations in the Lesser Himalayas and a significant decrease in erodibility coincident with the location of the MCT zone. This latter result possibly highlights the effect of intense schistosity and fracturation on large scale erosion efficiency [Molnar et al., 2007]. Then to assess the influence of erodibility on

  13. Eroders on a Plane with Three States at a Point. Part I: Deterministic

    NASA Astrophysics Data System (ADS)

    de Santana, L. H.; Ramos, A. D.; Toom, A.

    2015-06-01

    Imagine a huge (in theory, infinite) space, whose elements are called components. We say that we have a configuration, if for every component we have specified its state. All components have one and the same finite set of possible states and one of the elements of is called zero. If all the components of a configuration are zeros, we call it "all zeros". We are especially interested in those configurations, in which only a bounded set of components are in a state different from zero; such a configuration is called an island. Our time is discrete and we may imagine that, due to the forces of nature, at every time step the whole configuration (landscape) is subject to a deterministic uniform local rule such that non-zero components may appear only in the vicinity of already existing non-zero components (like in percolation or contact processes). We say that an operator erodes an island if there is a natural such that "all zeros", that is iterative applications of turn into "all zeros". We call an eroder if it erodes all islands. We look for an algorithm which decides for any whether it is an eroder or not and does it make islands grow or not. In general this problem is algorithmically unsolvable, so we need to restrict our scope; in addition to the afore-mentioned conditions we assume that is monotonic. Studying such processes one has to decide whether time and space are discrete or continuous and in this study we choose discrete time and continuous space just because this case is underrepresented in the literature. But especially important is the set of possible states of every single component. Years ago one of us (A. Toom) presented a rule to decide whether is an eroder for the case when every component has only two possible states. A. Toom also showed that if is an eroder, then it erodes any island in time, which is linear in the diameter of the island. In this work every component has three possible states. It turned out that the difference between two and three

  14. Restoration of Degraded/Eroded Soil under Different Management Practices in the Central Great Plains

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Farmlands in the Central Great Plains Region (CGPR) have lost topsoil through wind and water erosion induced by tillage and poor soil management. These soils are now degraded with low soil quality and productivity. Productivity and quality of degraded/eroded soils can be restored using manure and i...

  15. Eroded dentin does not jeopardize the bond strength of adhesive restorative materials.

    PubMed

    Cruz, Janaina Barros; Lenzi, Tathiane Larissa; Tedesco, Tamara Kerber; Guglielmi, Camila de Almeida Brandão; Raggio, Daniela Prócida

    2012-01-01

    This in vitro study evaluated the bond strength of adhesive restorative materials to sound and eroded dentin. Thirty-six bovine incisors were embedded in acrylic resin and ground to obtain flat buccal dentin surfaces. Specimens were randomly allocated in 2 groups: sound dentin (immersion in artificial saliva) and eroded dentin (pH cycling model - 3× / cola drink for 7 days). Specimens were then reassigned according to restorative material: glass ionomer cement (KetacTM Molar Easy Mix), resin-modified glass ionomer cement (VitremerTM) or adhesive system with resin composite (Adper Single Bond 2 + Filtek Z250). Polyethylene tubes with an internal diameter of 0.76 mm were placed over the dentin and filled with the material. The microshear bond test was performed after 24 h of water storage at 37ºC. The failure mode was evaluated using a stereomicroscope (400×). Bond strength data were analyzed with two-way ANOVA and Tukey's post hoc tests (α = 0.05). Eroded dentin showed bond strength values similar to those for sound dentin for all materials. The adhesive system showed the highest bond strength values, regardless of the substrate (p < 0.0001). For all groups, the adhesive/mixed failure prevailed. In conclusion, adhesive materials may be used in eroded dentin without jeopardizing the bonding quality. It is preferable to use an etch-and-rinse adhesive system because it shows the highest bond strength values compared with the glass ionomer cements tested. PMID:22714927

  16. Soil Properties and Productivity as Affected by Topsoil Movement within an Eroded Landform

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In hilly landforms subject to long-term cultivation, erosion has denuded upper slope positions of topsoil and accumulated topsoil in lower slope positions. One approach to remediate these eroded landforms is moving soil from areas of topsoil accumulation to areas of topsoil depletion, termed here so...

  17. 7 CFR 1430.225 - Violations of highly erodible land and wetland conservation provisions.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 10 2011-01-01 2011-01-01 false Violations of highly erodible land and wetland conservation provisions. 1430.225 Section 1430.225 Agriculture Regulations of the Department of Agriculture... wetland conservation provisions. The provisions of part 12 of this title apply to this part....

  18. 7 CFR 1412.68 - Compliance with highly erodible land and wetland conservation provisions.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 10 2011-01-01 2011-01-01 false Compliance with highly erodible land and wetland conservation provisions. 1412.68 Section 1412.68 Agriculture Regulations of the Department of Agriculture... and wetland conservation provisions. The provisions of part 12 of this title apply to this part....

  19. 7 CFR 1412.68 - Compliance with highly erodible land and wetland conservation provisions.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 10 2010-01-01 2010-01-01 false Compliance with highly erodible land and wetland conservation provisions. 1412.68 Section 1412.68 Agriculture Regulations of the Department of Agriculture... and wetland conservation provisions. The provisions of part 12 of this title apply to this part....

  20. 7 CFR 1412.68 - Compliance with highly erodible land and wetland conservation provisions.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 10 2013-01-01 2013-01-01 false Compliance with highly erodible land and wetland conservation provisions. 1412.68 Section 1412.68 Agriculture Regulations of the Department of Agriculture... and wetland conservation provisions. The provisions of part 12 of this title apply to this part....

  1. 7 CFR 1412.68 - Compliance with highly erodible land and wetland conservation provisions.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 10 2012-01-01 2012-01-01 false Compliance with highly erodible land and wetland conservation provisions. 1412.68 Section 1412.68 Agriculture Regulations of the Department of Agriculture... and wetland conservation provisions. The provisions of part 12 of this title apply to this part....

  2. 7 CFR 1430.225 - Violations of highly erodible land and wetland conservation provisions.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 10 2010-01-01 2010-01-01 false Violations of highly erodible land and wetland conservation provisions. 1430.225 Section 1430.225 Agriculture Regulations of the Department of Agriculture... wetland conservation provisions. The provisions of part 12 of this title apply to this part....

  3. 7 CFR 1430.225 - Violations of highly erodible land and wetland conservation provisions.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 10 2012-01-01 2012-01-01 false Violations of highly erodible land and wetland conservation provisions. 1430.225 Section 1430.225 Agriculture Regulations of the Department of Agriculture... wetland conservation provisions. The provisions of part 12 of this title apply to this part....

  4. 7 CFR 1412.68 - Compliance with highly erodible land and wetland conservation provisions.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 10 2014-01-01 2014-01-01 false Compliance with highly erodible land and wetland conservation provisions. 1412.68 Section 1412.68 Agriculture Regulations of the Department of Agriculture... and wetland conservation provisions. The provisions of part 12 of this title apply to this part....

  5. 7 CFR 1430.225 - Violations of highly erodible land and wetland conservation provisions.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 10 2013-01-01 2013-01-01 false Violations of highly erodible land and wetland conservation provisions. 1430.225 Section 1430.225 Agriculture Regulations of the Department of Agriculture... wetland conservation provisions. The provisions of part 12 of this title apply to this part....

  6. 7 CFR 1430.225 - Violations of highly erodible land and wetland conservation provisions.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 10 2014-01-01 2014-01-01 false Violations of highly erodible land and wetland conservation provisions. 1430.225 Section 1430.225 Agriculture Regulations of the Department of Agriculture... wetland conservation provisions. The provisions of part 12 of this title apply to this part....

  7. Solute Transport in Eroded and Rehabilitated Prairie Landforms. 2. Reactive Solute

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Information regarding the impact of varying soil, landscape, and climate conditions on the off-site transport of pesticides is critical to the development of improved pesticide management practices. We quantified the rate of S-metolachlor dissipation after fall and spring application in eroded and r...

  8. Scintigraphic demonstration of acute gastrointestinal bleeding caused by gallbladder carcinoma eroding the colon

    SciTech Connect

    Czerniak, A.; Zwas, S.T.; Rabau, M.Y.; Avigad, I.; Borag, B.; Wolfstein, I.

    1985-08-01

    Massive lower gastrointestinal (GI) bleeding caused by gallbladder carcinoma eroding into the colonic wall was demonstrated accurately by Tc-99m RBCs. In addition, retrograde bleeding into the gallbladder was also identified while arteriography did not show contrast extravasation. This case supports the use of Tc-99m RBCs over Tc-99m sulfur colloid for more accurate localization of lower GI bleeding.

  9. No-Till Management Effects on Soil Water and Wind Erodibility Parameters

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The extent to which no-till management improves water and wind erodibility parameters is not well understood. This study assessed changes in aggregate resistance to raindrops, dry aggregate wettability, and dry aggregate stability as well as their relationships with changes in soil organic carbon co...

  10. Settling Velocity, Aggregate Stability, and Interrill Erodibility of Soils Varying in Clay Mineralogy

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The relation of soil structural stability with soil erodibility depends on the mechanisms of aggregate disruption of different aggregate sizes and the measurement technique. In this study, we evaluated the relationship between settling velocity and stability of aggregates of different sizes, and int...

  11. Erodibility of a mixed mudflat dominated by microphytobenthos and Cerastoderma edule, East Frisian Wadden Sea, Germany

    NASA Astrophysics Data System (ADS)

    Andersen, T. J.; Lanuru, M.; van Bernem, C.; Pejrup, M.; Riethmueller, R.

    2010-04-01

    Sediment erodibility and a range of physical and biological parameters were measured at an intertidal site in the German Wadden Sea area in June, September and November 2002 and February and April 2003 in order to examine the influence of macrozoobenthos and microphytobenthos on sediment erodibility and the temporal variation. The study site was a mixed mudflat situated in the mesotidal Baltrum-Langeoog tidal basin at the East Frisian barrier coast. The mud content at the site was about 35% and the filter-feeding cockle Cerastoderma edule was the dominating macrozoobenthic species (by biomass). The erodibility of the sediment showed strong temporal variation with high erosion thresholds in spring and late summer and significantly lower thresholds during the rest of the study period. The erosion thresholds were strongly dependent on the contents of chlorophyll a (chl a) and colloidal carbohydrates, both indicators of the content of microphytobenthos, in this environment primarily benthic diatoms. The content of microphytobenthos was high in September 2002 and April 2003, and regression analysis indicated that this was the only likely reason for the low erodibility found at these times. A biostabilisation index of about 4.5 was found for a situation with both abundant biofilms and cockles. A direct influence of Cerastoderma edule on erodibility was not observed, in contrast to other recent studies. The presence of C. edule at the site results in biodeposition of fine-grained material and the presence of C. edule will therefore probably increase the content of fine-grained sediments at the surface compared to an abiotic situation. Increasing the amount of fine-grained material in mixed sediments has previously been shown to reduce the erodibility of the sediments and C. edule will therefore in this way indirectly stabilize the bed. However, although C. edule may constitute the main part of the biomass at some intertidal sites, other and more vigorous bioturbators and

  12. The role of temporally varying erodibility in hysteresis in fine-grained coastal systems

    NASA Astrophysics Data System (ADS)

    Wiberg, P.; Carr, J. A.

    2013-12-01

    Sediment transport rates are typically expressed as some function of excess shear stress, the difference between the fluid shear stress at the sediment surface and the shear stress needed to initiate transport of the sediment comprising the surface. While a great deal of research has addressed questions related to temporal and spatial variations in the fluid stresses driving transport and deposition, considerably less has focused on temporal and spatial variations in sediment erodibility. Most sediment transport relationships involved a critical shear stress that is at most a function of grain size and density for non-cohesive sediment or a function of depth for cohesive sediment. Such simple characterizations of erodibility are frequently inadequate for representing sediment dynamics in fine-grained coastal and shallow marine environments where a wide range of processes, including consolidation, biofilm production and bioturbation can cause dramatic temporal and spatial (horizontal and vertical) variations in erodibility. For example, flood deposits of mud on the continental shelf can initially be highly erodible, facilitating the formation of wave-supported gravity flows, but quickly (days-weeks) consolidate to the point where they can become relatively resistant to resuspension by large storm waves - well above traditional notions of 'storm wave base'. On the other hand, loss of protection by primary producers - such as a die off of seagrasses or biofilms - can release large quantities of previously stable sediment into a coastal system. In this talk we explore the importance of temporal variations in erodibility on coastal and shallow marine systems in producing path-dependence and hysteresis in fine-grained coastal systems.

  13. Water and dissolved carbon transport in an eroding soil landscape using column experiments

    NASA Astrophysics Data System (ADS)

    Rieckh, Helene; Gerke, Horst; Glæsner, Nadia; Kjaergaard, Charlotte; Sommer, Michael

    2014-05-01

    In the hummocky ground moraine soil landscape, a spatial continuum of more or less eroded soils developed from till under intensive agricultural cultivation. Water flow and solute transport are affected by the variable soil structural and pedological developments, which are posing a challenge for flux estimation. The objective of this study was to investigate transport of water, dissolved organic (DOC), and particulate carbon (PC) through soil profiles of an eroded Haplic Luvisol and a heavily eroded Haplic Regosol. We studied 5 soil horizons in three replicates each: Ap (0-20 cm) and E (20-40 cm and 40-60 cm) horizons of the eroded Haplic Luvisol and Ap (0-20 cm) and CBkg (20-40 cm) horizon of the Haplic Regosol. Leaching experiments were performed on intact soil columns (20 cm diameter, 20 cm height) and carried out during unsaturated conditions with a suction applied at the lower boundary. Breakthrough curves for a pre-applied tracer (Br-) on the soil surface and a tracer applied with irrigation water (3H2O) were modeled analytically using CXTFIT. The heterogeneity of the Luvisol horizons was generally higher than that of the Regosol horizons, which relates to the higher heterogeneity of the Luvisol bulk density. The active flow volume was smaller for the Regosol horizons both in 0-20 cm and 20-40 cm depths. The highest DOC leaching was from the E horizon (20-40 cm depth) located just underneath the Ap horizon of the Luvisol corresponding with its lower clay content. From the finding of a substantially lower leaching of particles from all Regosol horizons, we assume a lower transport of particulate C from the Haplic Regosol than from the eroded Haplic Luvisol. Results suggest that soil erosion not only affected the pedological structure and physical soil properties but also strongly the water and solute movement.

  14. Impacts of land use conversion on soil properties and soil erodibility.

    PubMed

    Korkanc, Selma Yasar; Ozyuvaci, Necdet; Hizal, Ahmet

    2008-05-01

    Land use conversion can affect natural ecological processes such as surface runoff and erosion. Therefore, it has potential to change soil stability To investigate this process in depth, Iskalan creek catchment in the Black sea region, where excessive land use applications and erosion events have often occured, was selected as the study area. The objective was to determine the effects of land use conversion on soil properties, soil erodibility and the relationships among soil properties and some erodibility indices. Duplicate topsoil samples were taken by using steel cylinders at 100 different sampling points from three different land use types; 34 of them are in farmlands, 34 in rangelands and 32 in forestlands. Soil particle size distribution, loss of ignition, pH, electrical conductivity skeleton percentage and three erodibility indices were determined. Data were analysed by using Pearson correlation analysis (at 95% and 99% significance level), ANOVA and Tukey's test at 95 % significance level. According to study results, land use conversion affects some properties of soils significantly Loss of ignition of soils in forests was significantly higher than soils in farmlands and rangelands. Soil skeleton percentage in rangelands and farmlands were significantly different. The study results showed that there was significant difference between pH of soils in forests and farmlands (p < 0.05). Pearson correlation analysis results showed significant correlations among erodibility indices and certain soil properties such as clay and sand fraction of soils (p < 0.05 and p < 0.01). Topsoils of the study area were sensitive to erosion according to all three erodibility indices. The most sensitive soils were in farmlands.

  15. Development a fluvial detachment rate model to predict the erodibility of cohesive soils under the influence of seepage

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Seepage influences the erodibility of streambanks, streambeds, dams, and embankments. Usually the erosion rate of cohesive soils due to fluvial forces is computed using an excess shear stress model, dependent on two major soil parameters: the critical shear stress (tc) and the erodibility coefficie...

  16. Incorporation of Fine-Grained Sediment Erodibility Measurements into Sediment Transport Modeling, Capitol Lake, Washington

    USGS Publications Warehouse

    Stevens, Andrew W.; Gelfenbaum, Guy; Elias, Edwin; Jones, Craig

    2008-01-01

    Capitol Lake was created in 1951 with the construction of a concrete dam and control gate that prevented salt-water intrusion into the newly formed lake and regulated flow of the Deschutes River into southern Puget Sound. Physical processes associated with the former tidally dominated estuary were altered, and the dam structure itself likely caused an increase in retention of sediment flowing into the lake from the Deschutes River. Several efforts to manage sediment accumulation in the lake, including dredging and the construction of sediment traps upriver, failed to stop the lake from filling with sediment. The Deschutes Estuary Feasibility Study (DEFS) was carried out to evaluate the possibility of removing the dam and restoring estuarine processes as an alternative ongoing lake management. An important component of DEFS was the creation of a hydrodynamic and sediment transport model of the restored Deschutes Estuary. Results from model simulations indicated that estuarine processes would be restored under each of four restoration alternatives, and that over time, the restored estuary would have morphological features similar to the predam estuary. The model also predicted that after dam-removal, a large portion of the sediment eroded from the lake bottom would be deposited near the Port of Olympia and a marina located in lower Budd Inlet seaward of the present dam. The volume of sediment transported downstream was a critical piece of information that managers needed to estimate the total cost of the proposed restoration project. However, the ability of the model to predict the magnitude of sediment transport in general and, in particular, the volume of sediment deposition in the port and marina was limited by a lack of information on the erodibility of fine-grained sediments in Capitol Lake. Cores at several sites throughout Capitol Lake were collected between October 31 and November 1, 2007. The erodibility of sediments in the cores was later determined in the

  17. Potential fate of SOC eroded from natural crusted soil surface under simulated wind driven storm

    NASA Astrophysics Data System (ADS)

    Xiao, Liangang; Fister, Wolfgang; Greenwood, Philip; Hu, Yaxian; Kuhn, Nikolaus J.

    2016-04-01

    Improving the assessment of the impact of soil erosion on carbon (C) cycling requires a better understanding of the redistribution of eroded sediment and associated soil organic carbon (SOC) across agricultural landscapes. Recent studies conducted on dry-sieved aggregates in the laboratory demonstrated that aggregation can profoundly skew SOC redistribution and its subsequent fate by accelerating settling velocities of aggregated sediment compared to mineral grains, which in turn can increase SOC mineralization into greenhouse gases. However, the erodibility of the soil in the field is more variable than in the laboratory due to tillage, crus formation, drying-wetting and freeze-thaw cycles, and biological effects. This study aimed to investigate the potential fate of the SOC eroded from naturally developed soil surface and to compare the observations with those made in the laboratory. Simulated, short, high intensity wind driven storms were conducted on a crusted loam in the field. The sediments were fractionated with a settling tube according to their potential transport distances. The soil mass, SOC concentration and cumulative 80-day CO2 emission of each fraction were identified. The results show: 1) 53% of eroded sediment and 62% of eroded SOC from the natural surface in the field would be deposited across landscapes, which is six times and three times higher compared to that implied by mineral grains, respectively; 2) the preferential deposition of SOC-rich fast-settling sediment potentially releases approximately 50% more CO2 than the same layer of the non-eroded soil; 3) the respiration of the slow-settling fraction that is potentially transported to the aquatic systems was much more active compared to the other fractions and the bulk soil. Our results confirm in general the conclusions drawn from laboratory and thus demonstrate that aggregation can affect the redistribution of sediment associated SOC under field conditions, including an increase in

  18. Tracing peatland geomorphology: sediment and contaminant movements in eroding and restored systems

    NASA Astrophysics Data System (ADS)

    Shuttleworth, Emma; Evans, Martin; Hutchinson, Simon; Rothwell, James

    2015-04-01

    Peatlands are an important store of soil carbon, play a vital role in global carbon cycling, and can also act as sinks of atmospherically deposited heavy metals. However, large areas of blanket peat are significantly degraded and actively eroding as a direct result of anthropogenic pressures, which negatively impacts carbon and pollutant storage. The restoration of eroding UK peatlands is a major conservation concern, and over the last decade measures have been taken to control erosion and restore large areas of degraded peat. In severely eroded peatlands, topography is highly variable, and an appreciation of geomorphological form and process is key in understanding the controls on peatland function, and in mitigating the negative impacts of peatland erosion. The blanket peats of the Peak District, Southern Pennines, UK embody many problems and pressures faced by peatlands globally, and are amongst the most heavily eroded and contaminated in the world. The near-surface layer of the peat is contaminated by high concentrations of anthropogenically derived, atmospherically deposited heavy metals which are released into the fluvial system as a consequence of widespread erosion. Whilst not desirable, this legacy of lead pollution and its release offer a unique opportunity to trace peatland sediment movements and thus investigate the controls on sediment and contaminant mobility. A suite of established field, analytical and modelling techniques have been modified and adapted for use in peatland environments and these have been successfully employed in combination to address issues of sediment and contaminant release at a range of scales, including: (i) the development of field portable XRF to assess in situ lead concentrations in wet organic sediments; (ii) adaptation of time integrated mass flux samplers to explore spatial and temporal sediment dynamics in peatland streams; and (iii) the application of sediment source fingerprinting and numerical mixing models to

  19. Eroding dipoles and vorticity growth for Euler flows in : axisymmetric flow without swirl

    NASA Astrophysics Data System (ADS)

    Childress, Stephen; Gilbert, Andrew D.; Valiant, Paul

    2016-10-01

    A review of analyses based upon anti-parallel vortex structures suggests that structurally stable vortex structures with eroding circulation may offer a path to the study of rapid vorticity growth in solutions of Euler's equations in $ \\scriptstyle{\\mathbb{R}}^3$. We examine here the possible formation of such a structure in axisymmetric flow without swirl, leading to maximal growth of vorticity as $t^{4/3}$. Our study suggests that the optimizing flow giving the $t^{4/3}$ growth mimics an exact solution of Euler's equations representing an eroding toroidal vortex dipole which locally conserves kinetic energy. The dipole cross-section is a perturbation of the classical Sadovskii dipole having piecewise constant vorticity, which breaks the symmetry of closed streamlines. The structure of this perturbed Sadovskii dipole is analyzed asymptotically at large times, and its predicted properties are verified numerically.

  20. Large-eddy simulation of the flow over a hydrokinetic turbine mounted on an erodible bed

    NASA Astrophysics Data System (ADS)

    Yang, Xiaolei; Khosronejad, Ali; Sotiropoulos, Fotis

    2013-11-01

    Marine and hydrokinetic (MHK) energy comprises an important source of clean and renewable energy. The beds of natural waterways are usually erodible. The hydrokinetic turbines affect the sediment transport, which, on the other hand, also influences the performance of hydrokinetic turbines. A powerful computational framework for simulating marine and hydrokinetic (MHK) turbine arrays mounted in complex river bathymetry with sediment transport has been developed and validated by our group. In this work we apply this method to simulate the turbulent flow over a hydrokinetic turbine mounted in an open channel with erodible bed. Preliminary results show qualitatively good agreement with the experiment. Detailed comparison with measurements and analysis of the simulation results will be presented in the conference. This work was supported by the University of Minnesota Initiative for Renewable Energy and the Environment IREE (grant no RO-0004-12). Computational resources were provided by the University of Minnesota Supercomputing Institute.

  1. Physical and numerical modeling of an interacting granular mass and an erodible layer

    NASA Astrophysics Data System (ADS)

    Crosta, G. B.; Imposimato, S.; Roddeman, D.; De Caro, M.; Volpi, G.

    2013-12-01

    This contribution tackle the problem of a fast moving granular mass flowing on a steep slope and successively along a horizontal erodible layer. This setting is typi-cal at many sites where rock avalanche can or already occurred. Then the rele-vance of such a condition lays in its frequency under natural conditions, the high energy content and the possible role of the entrapment of erodible material along the path which can strongly control the evolution of the landslide motion. A series of experimental tests has been performed on a simplified slope to analyze the effect of: released mass and volume, slope angle (35-65°) and thickness of erodible layer on the final runout, the geometry of the deposit, the time evolution of the flow and the erosion process. The experiment setup includes a high speed camera and a system for the monitoring of the flow characteristics which allows to catch the flow evolution in space and time. The adopted materials are a uni-form sand for both the released mass and the erodible layer, and an angular grav-el for the released mass only. These tests allow a better understanding of the pro-cesses in terms of major controlling factors on flow height and velocity, and of erosion capabilities and influence on motion. At the same time they provide a re-liable dataset to perform some numerical simulation and especially to validate the prediction performance of the used numerical code, which adopts an Euleri-an-Lagrangian method allowing to not distort the FE mesh guaranteeing accurate calculation results. This code has already been tested on other geometries showing very good capabilites at simulating long runout flows and erosion. Results are compared in terms of modes of propagation, erosion, velocity and depth of flow as well as considering the dynamic evolution of the flow geometry during the propagation as well as the deposition phase.

  2. Phosphorus Characterization and Contribution from Eroding Streambank Soils of Vermont's Lake Champlain Basin.

    PubMed

    Ishee, Eulaila R; Ross, Donald S; Garvey, Kerrie M; Bourgault, Rebecca R; Ford, Charlotte R

    2015-11-01

    Streambank erosion is an important contributor to sediment and nutrient export. This study determined total P (TP), soil-test P (Modified Morgan's, MM-P), and the degree of P saturation (DPS) in eroding riparian soils along four Lake Champlain Basin stream corridors. We investigated the relationship between these data and soil texture and with a series of GIS-derived landscape metrics. We also quantified the potential P load from eroding streambanks using remote sensing. Soil samples were taken from 76 erosion features to a depth of 90 cm on four streams in Chittenden County, Vermont. Mean concentrations of TP and MM-P were similar among the watersheds and through depth. Neither TP, MM-P, nor DPS were well related to texture. Metrics from available spatial databases for parent material, soil series, and landscape position were somewhat useful in predicting TP and MM-P. Eroding streambank soil from 2004 through 2007 in the four streams was estimated to contain from 0.5 to 3.9 Mg of TP and 1.4 to 10.9 kg MM-P. The mean DPS in each watershed was <18% and, along with low MM-P concentrations, suggests that eroded streambanks may act as sinks rather than sources of P. The portion of total nonpoint P export potentially contributed by streambank erosion ranged from 6% in the stream with the lowest erosion rate to 30% in the stream with the highest erosion rate. Based on TP values, the P contribution of these streambanks could be considerable, and more information is needed on their actual contribution to bioavailable P in receiving waters. PMID:26641326

  3. Alterations to Soil and Eroded Sediment Carbon after the Rim Fire, Yosemite National Park

    NASA Astrophysics Data System (ADS)

    Lever, R.; Berhe, A. A.; Fogel, M. L.; Hockaday, W. C.; Kuhn, T. J.; Austin, L. J.

    2015-12-01

    The soil system is a critical global carbon (C) pool that is under threat from both fire and erosion perturbations. In the Western United States, forecasted increases in average temperatures, as well as for extended summer growing seasons, indicate that large fuel loads and ideal fire conditions may generate more high intensity wildfires. Understanding how wildfires control soil C storage is critical for both projecting losses of soil C and how to better manage fire regimes to increase soil C storage. This research addresses a topic that has only been briefly addressed by the current body of literature - the erosion of pyrogenic C, or C which has undergone some combustion, which has the potential to affect storage of C within the soil system. The Rim Fire was a wildfire that consumed over 250,000 acres of land in Yosemite National Park and Stanislaus National Forest in 2013. After the fire, sediment traps were established on a hillslope under three treatment conditions: 1) high burn severity — high slope; 2) high burn severity — moderate slope, and; 3) moderate burn severity — high slope. Sediments were collected from these traps after every major precipitation event following the Rim Fire, Additionally, representative soils were collected from the source areas of the eroded material. Differences in chemical composition of organic matter and concentration of pyrogenic matter were determined using 13C Cross-Polarization Magic Angle Spinning (CPMAS) Nuclear Magnetic Resonance (NMR) spectroscopy, in addition to elemental and stable isotope analysis of carbon and nitrogen. Our results show that carbon eroded from areas of higher burn intensity generally had higher concentration of aromatic functional groups, compared to moderate burn intensity areas. Differences in the form of C eroded from areas of different burn intensity and slope steepness can be used as a proxy for determining how fire severity and geomorphology dictate the amount and nature of C eroded from

  4. Mapping erodibility in dust source regions based on geomorphology, meteorology, and remote sensing

    NASA Astrophysics Data System (ADS)

    Parajuli, Sagar Prasad; Yang, Zong-Liang; Kocurek, Gary

    2014-09-01

    Mineral dust in the atmosphere has implications for Earth's radiation budget, biogeochemical cycles, hydrological cycles, human health, and visibility. Currently, the simulated vertical mass flux of dust differs greatly among the existing dust models. While most of the models utilize an erodibility factor to characterize dust sources, this factor is assumed to be static, without sufficient characterization of the highly heterogeneous and dynamic nature of dust source regions. We present a high-resolution land cover map of the Middle East and North Africa (MENA) in which the terrain is classified by visually examining satellite images obtained from Google Earth Professional and Environmental Systems Research Institute Basemap. We show that the correlation between surface wind speed and Moderate Resolution Imaging Spectroradiometer deep blue aerosol optical depth (AOD) can be used as a proxy for erodibility, which satisfactorily represents the spatiotemporal distribution of soil-derived dust sources. This method also identifies agricultural dust sources and eliminates the satellite-observed dust component that arises from long-range transport, pollution, and biomass burning. The erodible land cover of the MENA region is grouped into nine categories: (1) bedrock: with sediment, (2) sand deposit, (3) sand deposit: on bedrock, (4) sand deposit: stabilized, (5) agricultural and urban area, (6) fluvial system, (7) stony surface, (8) playa/sabkha, and (9) savanna/grassland. Our results indicate that erodibility is linked to the land cover type and has regional variation. An improved land cover map, which explicitly accounts for sediment supply, availability, and transport capacity, may be necessary to represent the highly dynamic nature of dust sources in climate models.

  5. A conservative treatment approach using direct composite resins for anterior teeth eroded by lemon sucking.

    PubMed

    Passos, Vanara Florencio; de Souza, Andre Mattos Brito; Rodrigues, Lidiany Karla Azevedo; Bombonatti, Juliana Campos Fraga Soares; Santiago, Sergio Lima

    2013-08-01

    An excessively acidic diet results in the progressive deterioration of dental health, with functional, esthetic, and biological consequences. Previously, rehabilitation required placing numerous full crowns and root canal treatments; however, with improved adhesive techniques, a more conservative approach may be utilized to preserve tooth structure. This article describes 2 cases that utilized conservative dental treatments (involving direct composite resins with minimal preparation of the tooth structure) to treat eroded dentition induced by lemon sucking. PMID:23928446

  6. Frijolito Watershed: Integrated investigations of a rapidly eroding pinyon-juniper hillslope

    SciTech Connect

    Wilcox, B.P.; Pitlick, J.; Allen, C.D.

    1995-12-31

    The dramatic acceleration of erosion associated with the expansion of pinyon-juniper woodlands over the past 100 years has been widely recognized, but few process-based studies of this phenomenon have been undertaken. In an attempt to identify the underlying causes, and the factors that affect erosion processes, we have initiated an interdisciplinary study of a rapidly eroding pinyon-juniper woodland in northern New Mexico. Since July 1993, we have collected data on runoff, erosion, and weather conditions from a 1-ha catchment study area and have conducted surveys of topography, soils, and vegetation. Our preliminary results indicate that although runoff makes up less than 10% of the annual water budget, runoff events - which are frequent in the summer - are capable of moving large amounts of sediment. We estimate that between July 1993 and October 1994, between 25,000 and 50,000 kg of sediment has eroded and been transported from the catchment. The information gained from such studies is essential to our ability to formulate effective strategies for managing these rapidly eroding woodlands.

  7. Impacts of peatland restoration on dissolved carbon loss from eroded upland peatlands in the UK

    NASA Astrophysics Data System (ADS)

    Evans, M.; Stimson, A.; Allott, T. E. H. A.; Holland, N.

    2012-04-01

    Upland blanket peatlands in the UK are severely degraded by extensive gully erosion. Large areas have experienced complete vegetation loss. In the last decade landscape scale approaches to the restoration of eroded and bare peat have been developed in the Peak District National Park in northern England. Bare peat is re-vegetated with a nurse crop of grasses established by the aerial application of lime, seed, and fertiliser. The approach has successfully re-vegetated large areas of eroded bog a nd has been shown to dramatically reduce particulate carbon losses in runoff. The impacts of the treatment on water quality and dissolved carbon loss have not previously been fully assessed. This paper reports results from a small catchment study assessing the impacts of restoration practice in the Peak District. Data from five small catchments are presented one re-vegetated, one intact and three eroded/bare catchments. Bi-weekly water samples have been taken from the catchments between January 2011 and February 2012 and during July 2012 two of the bare sites were treated with lime, seed, and fertiliser. The data show that there are significant spikes in nutrient flux post treatment and marked effects on dissolved carbon which include initial spikes in in DOC concentration but longer term reductions in DOC concentration. Monitoring is ongoing at these sites but the evidence to date points to at least a short term benefit in DOC flux reduction from this form of peatland restoration.

  8. Eroded swimmeret syndrome in female crayfish Pacifastacus leniusculus associated with Aphanomyces astaci and Fusarium spp. infections.

    PubMed

    Edsman, Lennart; Nyström, Per; Sandström, Alfred; Stenberg, Marika; Kokko, Harri; Tiitinen, Vesa; Makkonen, Jenny; Jussila, Japo

    2015-01-15

    We describe a novel syndrome in crayfish, eroded swimmeret syndrome (ESS), affecting wild female signal crayfish Pacifastacus leniusculus. ESS causes partial or total swimmeret erosion. We observed ESS only in female signal crayfish larger than 40 mm carapace length, i.e. sexually mature and probably having carried eggs at least once. The eroded swimmerets were melanised, indicating a crayfish immune system response. We isolated Fusarium tricinctum species complex (SC), F. sambucinum SC, Saprolegnia parasitica and S. australis from the melanised tissue of the eroded swimmerets. ESS includes chronic Aphanomyces astaci infection and a secondary infection by Fusarium sp. In Sweden, we found female signal crayfish with ESS in 6 out of 11 populations with a prevalence below 1% in lakes with commercially productive signal crayfish populations and higher than 29% in lakes with documented signal crayfish population crashes. In Finland, the ESS prevalence was from 3.4 to 6.2% in a commercially productive population. None of the sampled male signal crayfish showed signs of ESS. A caging experiment indicated that females with at least 1 lost swimmeret carried on average 25% fewer fertilized eggs compared to females with intact swimmerets. ESS could significantly reduce individual female fecundity and thus could also affect fecundity at the population level. The decline in reproductive success due to ESS could be among the factors contributing to fluctuations in wild signal crayfish populations.

  9. Air jet erosion test on plasma sprayed surface by varying erodent impingement pressure and impingement angle

    NASA Astrophysics Data System (ADS)

    Behera, Ajit; Behera, Asit; Mishra, S. C.; Pani, S.; Parida, P.

    2015-02-01

    Fly-ash premixed with quartz and illmenite powder in different weight proportions are thermal sprayed on mild steel and copper substrates at various input power levels of the plasma torch ranging from 11 kW to 21 kW DC. The erosion test has done using Air Jet erosion test Reg (As per ASTM G76) with silica erodent typically 150-250 pm in size. Multiple tests were performed at increasing the time duration from 60 sec to 180 sec with increasing pressure (from 1 bar to 2.5 bar) and angle (60° & 90°). This study reveals that the impact velocity and impact angle are two most significant parameters among various factors influencing the wear rate of these coatings. The mechanisms and microstructural changes that arise during erosion wear are studied by using SEM. It is found that, when erodent are impacting the fresh un-eroded surface, material removal occurs by the continuous evolution of craters on the surface. Upper layer splats are removed out after 60 sec and second layer splat erosion starts. Based on these observations Physical models are developed. Some graphs plotted between mass loss-rate versus time period/impact Pressure/impact Angle gives good correlation with surface features observed.

  10. Erodibility of cohesive streambeds in the loess area of the midwestern USA

    NASA Astrophysics Data System (ADS)

    Hanson, G. J.; Simon, A.

    2001-01-01

    Excess stress parameters, critical shear stress (c) and erodibility coefficient (kd), for degrading channels in the loess areas of the midwestern USA are presented based on in situ jet-testing measurements. Critical shear stress and kd are used to define the erosion resistance of the streambed. The jet-testing apparatus applies hydraulic stresses to the bed and the resulting scour due to the impinging jet is related to the excess stress parameters. Streams tested were primarily silt-bedded in texture with low densities, which is typical of loess soils. Results indicate that there is a wide variation in the erosion resistance of streambeds, spanning six orders of magnitude for c and four orders of magnitude for kd. Erosion resistance was observed to vary within a streambed, from streambed to streambed, and from region to region. An example of the diversity of materials within a river system is the Yalobusha River Basin in Mississippi. The median value of c for the two primary bed materials, Naheola and Porters Creek Clay Formations, was 1·31 and 256 Pa, respectively. Streambeds composed of the Naheola Formation are readily eroded over the entire range of shear stresses, whereas only the deepest flows generate boundary stresses great enough to erode streambeds composed of the Porters Creek Clay Formation. Therefore, assessing material resistance and location is essential in classifying and modelling streambed erosion processes of these streams.

  11. Mechanisms of soil organic matter stabilization in sediments eroded from small Sierra Nevada catchments

    NASA Astrophysics Data System (ADS)

    Stacy, E.; Hart, S. C.; Hunsaker, C. T.; Johnson, D.; Berhe, A.

    2011-12-01

    Lateral redistribution of soil and associated soil organic matter (SOM) by soil erosion imposes significant controls on SOM dynamics within the eroding watershed, and the overall carbon (C) sequestration potential of the terrestrial biosphere. For sediments exported from eroding watersheds, biochemical composition is a function of SOM in the eroding slope profiles, the type of erosion, duration of transport, and the intensity of decomposition that occurs during transport. Eroded SOM stability, including its molecular architecture and associations with soil minerals, influences complex decomposition dynamics involving microbial activity and abiotic factors during transit and after deposition. Sediment traps located at the point where the first-order stream leaves the watershed provide insight into the material removed by these nearly ephemeral streams before the sediment passes into a larger adjacent watershed. This study investigates the variability in amount and composition of SOM eroded from eight first-order watersheds in the mixed-conifer zone of the Sierra National Forest in the Kings River Experimental Watershed. These watersheds range in size from 48.7 to 650 ha, and have predominately western aspects and granitic bedrock. We are determining the interannual variation in the biochemical composition and stability of SOM of the annual sediment load, and how it relates to the composition of the upslope soil in the watershed. Previous work indicates that the dry weight of sediment transported by the streams may vary by more than two orders of magnitude between years and between watersheds (when normalized to kg/ha; Eagan et al. 2004). Our preliminary results show that the carbon to nitrogen (C:N) ratio of the sediment is less variable between years and watersheds, and is similar to the C:N ratio of surface soils from upslope positions. High concentrations of particulate organic matter in the sediment contribute to higher C concentrations in the sediments than in

  12. EROD induction in microsomes and primary hepatocyte cultures prepared from individual double-crested cormorant embryo livers

    SciTech Connect

    Davis, J.A.; Fry, D.M.; Wilson, B.W.

    1994-12-31

    Double-crested cormorants (Phalacrocorax auritus) are being studied as a high trophic level indicator species for toxic contamination in San Francisco Bay and other locations on the California coast. In 1993, median ethoxyresorufin-o-deethylase (EROD) activities in embryo liver microsomes sampled from San Francisco Bay colonies were 4.2-fold and 2.3-fold higher than two coastal locations. In 1994 cormorant embryo livers from these same locations were again analyzed for liver microsomal EROD activity. In addition, basal and maximal EROD activity were measured in primary hepatocyte cultures from portions of the same livers used for microsomal EROD analysis to determine whether factors other than contaminant burdens in the egg contribute to the observed differences in activity. Differences in basal activity and induction capacity among the populations are discussed in the context of the hypothesis that polluted habitats select for increased metabolic capacity in affected populations.

  13. Sediment texture, erodibility, and composition in the Northern Gulf of Mexico and their potential impacts on hypoxia formation

    NASA Astrophysics Data System (ADS)

    Mickey, Rangley; Xu, Kehui; Libes, Susan; Hill, Jenna

    2015-02-01

    A region of hypoxic waters has formed annually over the past several decades in the northern Gulf of Mexico. This has motivated the studies of mechanisms controlling the development of hypoxia. Both field and laboratory approaches were used to examine sediment texture, erodibility, and composition. Sediment texture analyses show that grain size relates to the proximity to the Mississippi and Atchafalaya river deltas and to the remnants of shifts in the Mississippi and Atchafalaya deltaic lobes. Temporal variability in erodibility relates to seasonal weather patterns, with more energetic wave conditions in winter and spring setting up an active bottom layer that increases erodibility, compared to quiescent summers that allow for seabed consolidation. The amount of eroded material is fairly low until shear stress levels in the bottom boundary layer exceed 0.4 Pa. An organically enriched fluff layer was found at the sediment-water interface, which is highly erodible under low shear stress levels. Eroded volatile suspended solids (a proxy for organic material) vs. increasing levels of shear stress revealed a distinct pattern at all sample areas; higher concentrations of organic material were eroded at the lowest (0.01 Pa) and highest (0.6 Pa) applied shear stresses, and there was a higher ratio of the volatile to total suspended solids at 0.01 Pa. Based on erodibility experiments and modeling data analysis, the low shear stress levels during the quiescent periods in summer were sometimes high enough to resuspend this fluff layer, but not underlying sediment, thereby potentially facilitating the development of bottom water hypoxia.

  14. Influence of biochar and terra preta substrates on wettability and erodibility of soils

    NASA Astrophysics Data System (ADS)

    Smetanova, A.; Dotterweich, M.; Diehl, D.; Ulrich, U.; Fohrer, N.

    2012-04-01

    Biochar (BC) and terra preta substrates (TPS) have recently been promoted as soil amendments suitable for soil stabilization, soil amelioration and long-term carbon sequestration. BC is a carbon-enriched substance produced by thermal decomposition of organic material. TPS is composed of liquid and solid organic matter, including BC, altered by acid-lactic fermentation. Their effect on wettability, soil erodibility and nutrient discharge through overland flow was studied by laboratory experiments. At water contents between 0 and 100% BC is water repellent, while TPS changes from a wettable into a repellent state. The 5 and 10 vol % mixtures of BC and 10 and 20 vol% mixtures of TPS with sand remain mainly wettable during drying but repellency maxima are shifted to higher water contents with respect to pure sand and are mainly of subcritical nature. The runoff response was dominated by infiltration properties of the substrates rather than their wettability.Only one mixtures (20% TPS) produced more runoff than sandy-loamy soil on a 15% slope at an intensity of 25 mm•h-1. The 10% BC decreased runoff by up to 40%. At higher rainfall intensities (45 and 55 mm•h-1) the 10% TPS7 was up to 35% less erodible than 10% BC. Despite the TPS containing more nutrients, nutrient discharge varied between types of nutrients, slopes, rainfall intensities and mixtures. The application of a 1 cm layer onto the soil surface instead of 10% mixtures is not recommended due to high nutrient concentrations in the runoff and the wettability of pure substrates. The usage of 10% BC in lowland areas with low frequency and low-intensity precipitation and 10% TPS7 in areas with higher rainfall intensities appears to be appropriate and commendable according to current results. However, together with reversibility of repellency, it needs to undergo further examination in the field under different environmental and land use conditions Key words: biochar, terra preta substrate, wettability

  15. Landslides as weathering reactors; links between physical erosion and weathering in rapidly eroding mountain belts

    NASA Astrophysics Data System (ADS)

    Emberson, R.; Hovius, N.; Galy, A.

    2014-12-01

    The link between physical erosion and chemical weathering is generally modelled with a surface-blanketing weathering zone, where the supply of fresh minerals is tied to the average rate of denudation. In very fast eroding environments, however, sediment production is dominated by landsliding, which acts in a stochastic fashion across the landscape, contrasting strongly with more uniform denudation models. If physical erosion is a driver of weathering at the highest erosion rates, then an alternative weathering model is required. Here we show that landslides can be effective 'weathering reactors'. Previous work modelling the effect of landslides on chemical weathering (Gabet 2007) considered the fresh bedrock surfaces exposed in landslide scars. However, fracturing during the landslide motion generates fresh surfaces, the total surface area of which exceeds that of the exposed scar by many orders of magnitude. Moreover, landslides introduce concavity into hillslopes, which acts to catch precipitation. This is funnelled into a deposit of highly fragmented rock mass with large reactive surface area and limited hydraulic conductivity (Lo et al. 2007). This allows percolating water reaction time for chemical weathering; any admixture of macerated organic debris could yield organic acid to further accelerate weathering. In the South island of New Zealand, seepage from recent landslide deposits has systematically high solute concentrations, far outstripping concentration in runoff from locations where soils are present. River total dissolved load in the western Southern Alps is highly correlated with the rate of recent (<35yrs) landsliding, suggesting that landslides are the dominant locus of weathering in this rapidly eroding landscape. A tight link between landsliding and weathering implies that localized weathering migrates through the landscape with physical erosion; this contrasts with persistent and ubiquitous weathering associated with soil production. Solute

  16. Wind erodibility response of physical and biological crusts to rain and flooding

    NASA Astrophysics Data System (ADS)

    Aubault, H.; Bullard, J. E.; Strong, C. L.; Ghadiri, H.; McTainsh, G. H.

    2015-12-01

    Soil surface crusts are important controllers of the small-scale wind entrainment processes that occur across all dust source regions globally. The crust type influences water and wind erosion by impacting infiltration, runoff, threshold wind velocity and surface storage capacity of both water and loose erodible material. The spatial and temporal patterning of both physical and biological crusts is known to change with rainfall and flooding. However, little is known about the impact of differing water quantity (from light rainfall through to flooding) on soil crusting characteristics (strength, roughness, sediment loss). This study compares the response of two soil types (loamy sand - LS, sandy loam - SL) with and without BSCs to three different rainfall events (2mm, 8mm, 15mm). Two BSC treatments were used one that simulated a young cyanobacteria dominated crust and an older flood induced multi species biological crust. For both soil types, soil surface strength increased with increasing rainfall amount with LS having consistently higher resistance to rupture than SL. Regardless of texture, soils with BSCs were more resistant and strength did not change in response to rainfall impact. Soil loss due to wind erosion was substantially higher on bare LS (4 times higher) and SL (3 times higher) soils compared with those with BSCs. Our results also show that young biological crust (formed by the rainfall event) have reduced soil erodibility with notably greater strength, roughness and reduced sediment losses when compared to soils with physical crust. Interestingly though, the erodibility of the old BSC did not differ greatly from that of the young BSC with respect to strength, roughness and sediment loss. This raises questions regarding the rapid soil surface protection offered by young colonising cyanobacteria crusts. Further analyses exploring the role of biological soil crusts on surface response to rainfall and wind saltation impact are ongoing.

  17. Chemical transfers along slowly eroding catenas developed on granitic cratons in southern Africa

    USGS Publications Warehouse

    Khomo, Lesego; Bern, Carleton R.; Hartshorn, Anthony S.; Rogers, Kevin H.; Chadwick, Oliver A.

    2013-01-01

    A catena is a series of distinct but co-evolving soils arrayed along a slope. On low-slope, slowly eroding catenas the redistribution of mass occurs predominantly as plasma, the dissolved and suspended constituents in soil water. We applied mass balance methods to track how redistribution via plasma contributed to physical and geochemical differentiation of nine slowly eroding (~ 5 mm ky− 1) granitic catenas. The catenas were arrayed in a 3 × 3 climate by relief matrix and located in Kruger National Park, South Africa. Most of the catenas contained at least one illuviated soil profile that had undergone more volumetric expansion and less mass loss, and these soils were located in the lower halves of the slopes. By comparison, the majority of slope positions were eluviated. Soils from the wetter climates (550 and 730 mm precipitation yr− 1) generally had undergone greater collapse and lost more mass, while soils in the drier climate (470 mm yr− 1) had undergone expansion and lost less mass. Effects of differences in catena relief were less clear. Within each climate zone, soil horizon mass loss and strain were correlated, as were losses of most major elements, illustrating the predominant influence of primary mineral weathering. Nevertheless, mass loss and volumetric collapse did not become extreme because of the skeleton of resistant primary mineral grains inherited from the granite. Colloidal clay redistribution, as traced by the ratio of Ti to Zr in soil, suggested clay losses via suspension from catena eluvial zones. Thus illuviation of colloidal clays into downslope soils may be crucial to catena development by restricting subsurface flow there. Our analysis provides quantitative support for the conceptual understanding of catenas in cratonic landscapes and provides an endmember reference point in understanding the development of slowly eroding soil landscapes.

  18. Cytochrome P450 induction in mallard duck (MD), black-crowned night heron (BCNH) and Fisher-344 rat

    USGS Publications Warehouse

    Melancon, M.J.; Rattner, B.A.; Stegeman, John J.

    1991-01-01

    P450 induction was studied in adult and pipping MDs, pipping BCNHs, and rats. Adult MDs and rats received i.p. injection of corn oil, 3-methylcholanthrene (MC) in corn oil (20 mg/kg), saline or phenobarbital (PB) in saline (80 mg/kg) for 3 days. MD and BCNH embryos received MC and PB by injection into the aircell approximately 2 days before pipping and were sacrificed at pipping. Hepatic microsomes were assayed for protein, arylhydrocarbon hydroxylase (AHH), benzphetamine-N-demethylase (BEND), ethoxy-resorufin-O-dealkylase (EROD), pentoxyresorufin-O-dealkylase (PROD), benzyloxyresorufin-O-dealkylase (BROD), ethoxycoumarin-O-dealkylase (ECOD), and by SDS-PAGE with western blot using a polyclonal anti-P4S0IIB antibody and a monoclonal anti-P450IA antibody (MAb 1-12-3). Although species and age caused substantial differences in responses, all treated groups showed an increase in one or more monooxygenase assays. All animals treated with MC showed a strong induction of a protein recognized by anti-P450IA, and all those treated with PB showed strong induction of a band recognized by anti-P450IIB.

  19. Slope evolution at the Calvert Cliffs, Maryland -- measuring the change from eroding bluffs to stable slopes

    USGS Publications Warehouse

    Herzog, Martha; Larsen, Curtis E.; McRae, Michele

    2002-01-01

    Despite a long history of geomorphic studies, it is difficult to ascertain the time required for slopes to change from near vertical exposures to relatively stable slopes due to inadequate age control. Actively eroding coastal bluffs along the western shore of the Chesapeake Bay provide a key for understanding the centennial-scale development of stable slopes from eroding bluff faces. The Calvert Cliffs are composed of sandy silts, silty sands, and clayey silts of Miocene-age. Active wave erosion at the bluff toes encourages rapid sloughing from bluff faces and maintains slope angles of 70-80 degrees and relatively constant bluff-retreat rates. Naturally stabilized slopes are preserved as a fossil bluff line inland from a prograding cuspate foreland at Cove Point. The foreland is migrating southward at a rate of ca. 1.5 m/yr. As it moves south, it progressively protects bluffs from wave action as new beaches are deposited at their toes. Wave erosion is reinitiated at the northern end of the complex as the landform passes. An incremental record of slope change is preserved along the fossil bluff line. 14C dating of swales between beach ridges shows the complex to span 1700 years of progressive migration history. We hypothesized that slopes would change from steep, eroding faces to low-angle slopes covered with vegetation and sought to document the rate of change. Our team measured slope angles at intervals along the fossil bluff line and dated profiles by interpolating 14C ages of adjacent beach ridges. There was no progressive decrease in slope with age. All slopes along the fossil bluff line were 30-40 degrees with a mean of 35 degrees. Constancy in slope angle suggests that steep, actively eroding bluffs were quickly changed to stable slopes by landslides and slumping once they were protected. Given the accuracy of our age control, we conclude that the time required to attain a stable slope under natural processes is less than one century. This indicates that

  20. Numerical simulation of evolutionary erodible bedforms using the particle finite element method

    NASA Astrophysics Data System (ADS)

    Bravo, Rafael; Becker, Pablo; Ortiz, Pablo

    2016-07-01

    This paper presents a numerical strategy for the simulation of flows with evolutionary erodible boundaries. The fluid equations are fully resolved in 3D, while the sediment transport is modelled using the Exner equation and solved with an explicit Lagrangian procedure based on a fixed 2D mesh. Flow and sediment are coupled in geometry by deforming the fluid mesh in the vertical direction and in velocities with the experimental sediment flux computed using the Meyer Peter Müller model. A comparison with real experiments on channels is performed, giving good agreement.

  1. Microstructure and far infrared emission properties of tourmaline powders eroded by hydrochloric acid.

    PubMed

    Liang, Jinsheng; Li, Juan; Meng, Junping; Ding, Yan; Xue, Gang

    2010-03-01

    The microstructure and far infrared emission properties of tourmaline powders eroded by hydrochloric acid were investigated. The indexes including crystal structure, unit cell volume, microstructure and infrared spectra were characterized by X-ray diffraction, transmission electron microscopy, and Fourier transform infrared spectroscopy. The results show that the crystal structure was not changed; however, the unit cell volume decreased, the angularities of tourmaline particles became smooth, and there appeared nanohollows on their surfaces. The infrared emission properties were enhanced at proper concentrations of hydrochloric acid solutions. PMID:20355630

  2. Microstructure and far infrared emission properties of tourmaline powders eroded by hydrochloric acid.

    PubMed

    Liang, Jinsheng; Li, Juan; Meng, Junping; Ding, Yan; Xue, Gang

    2010-03-01

    The microstructure and far infrared emission properties of tourmaline powders eroded by hydrochloric acid were investigated. The indexes including crystal structure, unit cell volume, microstructure and infrared spectra were characterized by X-ray diffraction, transmission electron microscopy, and Fourier transform infrared spectroscopy. The results show that the crystal structure was not changed; however, the unit cell volume decreased, the angularities of tourmaline particles became smooth, and there appeared nanohollows on their surfaces. The infrared emission properties were enhanced at proper concentrations of hydrochloric acid solutions.

  3. Fractal dimension of soil aggregates as an index of soil erodibility

    NASA Astrophysics Data System (ADS)

    Ahmadi, Abbas; Neyshabouri, Mohammad-Reza; Rouhipour, Hassan; Asadi, Hossein

    2011-04-01

    SummaryAggregate stability is an influential factor governing soil erodibility. The fractal dimension of soil aggregates has been related to their size distributions and stabilities. Several fractal models have been proposed for estimating fractal dimension of soil aggregates. This study was conducted to investigate how closely the soil interrill erodibility factor in WEPP model can be correlated to and predicted from soil aggregate size distribution or from their fractal dimensions. Samples from 36 soil series with contrasting properties were collected from northwest of Iran. The fractal dimensions of soil aggregates were calculated from Rieu and Sposito ( D n), Tyler and Wheatcraft ( D mT), and Young and Crawford ( D mY) models using aggregate size distribution (ASD) data. A rainfall simulator with drainable tilting flume (1 × 0.5 m) at slope of 9% was employed and total interrill erosion ( TIE), total splashed soil ( TS) and interrill erodibility factor ( K i) were calculated for 20, 37, and 47 mm h -1 rainfall intensities. Results showed that both D n and D mT estimated from aggregate wet-sieving data characterized ASD of the examined soils and significantly ( p < 0.01) correlated to TS, TIE and K i. Values of D n and D mT estimated from dry-sieving data only correlated to TS but not to TIE and K i. Using air-dried aggregates of 4.75-8 mm size range, instead of aggregates <4.75 mm, in wet-sieving was better for estimating D n as an index for the predication of TIE, TS and K i. Correction of ASD for the particle fraction greater than lower sieve mesh size in each size class decreased the correlation coefficient between TIE, TS or K i and D n or D mT. The values of D mY were not correlated to TS, TIE and K i. The correlation coefficient TIE and K i with D n and D mT derived from wet-sieving data, were higher than those with wet-aggregate stability (WAS), mean weight diameter (MWD) and geometric mean diameter (GMD), implying that D n and D mT may be better

  4. Temporal changes of ethoxyresorufin-o-deethylase (EROD) activities and lysosome accumulation in intestine of fish on chronic exposure to dietary benzo[a]pyrene: linking erod induction to cytological effects.

    PubMed

    Yuen, Bonny B H; Au, Doris W T

    2006-10-01

    Temporal changes of intestinal and hepatic ethoxyresorufin-O-deethylase (EROD) activities and quantitative changes of secondary and tertiary (e.g., 2 degrees/3 degrees) lysosomes in enterocytes were compared for the juvenile grouper (Epinephelus coioides) on chronic exposure to foodborne benzo[a]pyrene (BaP) at two environmentally realistic levels (0.25 and 12.5 microg/g fish/d) over a four-week exposure and four-week depuration period. Intestinal EROD induction was rapid (within 3 d) and sustained in the BaP-exposed fish, while a fast recovery (within one week) was observed on withdrawal of BaP intake. A dose-response relationship was demonstrated between intestinal EROD activities and the levels of foodborne BaP. Conversely, hepatic EROD induction was weak and subsided rapidly in the exposed fish, signifying that hepatic EROD activity is not a good indicator of oral intake of BaP. Significant increase of 2 degrees/3 degrees lysosomes, as measured by Vv(lysosome, mucosa), was detected in young enterocytes of fish in the high-dosing group (12.5 microg/g fish/d) at exposure day 3 and persisted until recovery week 2. Importantly, intestinal EROD activity was significantly correlated to 2 degrees/3 degrees lysosome accumulation in enterocytes (r = 0.571, p < 0.001). These results further corroborate our earlier findings that induction of EROD activities in fish do not merely indicate exposure to BaP but also are correlated to harmful biological effects. We recommend the use of these two biochemical and cytological changes in intestines as specific biomarkers to indicate current and recent exposure of fish to BaP via oral intake.

  5. TIE of a PAH-contaminated sediment using reproductive responses and EROD induction in rainbow trout

    SciTech Connect

    Brumley, C.M.; Kraak, G. van der; Munkittrick, K.R.

    1995-12-31

    PAH-contaminated sediments have been shown to cause a range of effects in fish. However, identifying the effective compounds can be time consuming and expensive. A toxicity identification evaluation (TIE) involves the analysis of mixtures by initially separating the mixture into toxic and non-toxic constituents. In this study, sediment was collected from Hamilton Harbor, Lake Ontario, and either extracted wet using methanol (MeOH) and dichloromethane (DCM), or freeze-dried and soxhlet extracted with MeOH and DCM. DCM extracts were solvent exchanged with dimethylsulfoxide (DMSO). Juvenile rainbow trout (Oncorhynchus mykiss) were exposed through the water to wet, freeze-dried, or extracted sediment, or to the MeOH or DMSO extracts for 4 days. Fish were analyzed for hepatic EROD activity, and plasma DMSO extracts, but was unaffected in fish exposed to extracted sediment. Estradiol levels were increased in fish exposed to the wet sediment, but not in fish exposed to the freeze-dried or extracted sediment, nor either of the solvent extracts. The response of testosterone to wet, freeze-dried and extracted sediment was inconsistent. Results indicate that both of the extraction methods efficiently removed from the sediment the compounds responsible for the effects on EROD activity and estradiol levels. However, neither method retained in the solvent extracts the compounds causing the increases in estradiol levels. Work continues to refine the freeze-drying and extraction methods; extracts will then be further fractionated using HPLC to identify the compounds of concern.

  6. Spatial variability of soil properties and soil erodibility in the Alqueva reservoir watershed

    NASA Astrophysics Data System (ADS)

    Ferreira, V.; Panagopoulos, T.; Andrade, R.; Guerrero, C.; Loures, L.

    2015-04-01

    The aim of this work is to investigate how the spatial variability of soil properties and soil erodibility (K factor) were affected by the changes in land use allowed by irrigation with water from a reservoir in a semiarid area. To this end, three areas representative of different land uses (agroforestry grassland, lucerne crop and olive orchard) were studied within a 900 ha farm. The interrelationships between variables were analyzed by multivariate techniques and extrapolated using geostatistics. The results confirmed differences between land uses for all properties analyzed, which was explained mainly by the existence of diverse management practices (tillage, fertilization and irrigation), vegetation cover and local soil characteristics. Soil organic matter, clay and nitrogen content decreased significantly, while the K factor increased with intensive cultivation. The HJ-Biplot methodology was used to represent the variation of soil erodibility properties grouped in land uses. Native grassland was the least correlated with the other land uses. The K factor demonstrated high correlation mainly with very fine sand and silt. The maps produced with geostatistics were crucial to understand the current spatial variability in the Alqueva region. Facing the intensification of land-use conversion, a sustainable management is needed to introduce protective measures to control soil erosion.

  7. Spatial variability of soil properties and soil erodibility in the Alqueva dam watershed, Portugal

    NASA Astrophysics Data System (ADS)

    Ferreira, V.; Panagopoulos, T.; Andrade, R.; Guerrero, C.; Loures, L.

    2015-01-01

    The aim of this work is to investigate how the spatial variability of soil properties and soil erodibility (K factor) were affected by the changes in land use allowed by irrigation with water from a reservoir in a semiarid area. To this, three areas representative of different land uses (agroforestry grassland, Lucerne crop and olive orchard) were studied within a 900 ha farm. The interrelationships between variables were analyzed by multivariate techniques and extrapolated using geostatistics. The results confirmed differences between land uses for all properties analyzed, which was explained mainly by the existence of diverse management practices (tillage, fertilization and irrigation), vegetation cover and local soil characteristics. Soil organic matter, clay and nitrogen content decreased significantly, while K factor increased with intensive cultivation. The HJ-biplot methodology was used to represent the variation of soil erodibility properties grouped in land uses. Native grassland was the least correlated with the other land uses. K factor demonstrated high correlation mainly with very fine sand and silt. The maps produced with geostatistics were crucial to understand the current spatial variability in the Alqueva region. Facing the intensification of land-use conversion, a sustainable management is needed to introduce protective measures to control soil erosion.

  8. Remote Sensing Analysis of a Rapidly Eroding Sea Cliff at Point Grey, British Columbia

    NASA Astrophysics Data System (ADS)

    Westin, A. M.; Francioni, M.; Kremsater, R.; Stead, D.; Clague, J. J.

    2015-12-01

    A range of remote sensing tools can be used to document hazardous and sensitive environments. Presented at this time are the first results of an ongoing study of a rapidly eroding, steep sea cliff in Vancouver, British Columbia. The sea cliff is formed in a 70-m-thick sequence of outwash sands and silts (Quadra Sand) deposited during the early part of the last glaciation, known locally as the Fraser Glaciation. The sea cliff is unstable and retreating due to wave attack, groundwater seepage, and shallow-seated landslides. If no measures are taken to stem wave erosion, the sea cliff will likely retreat faster with rising seas over the remainder of this century. The beach below the cliff is a popular recreational location, thus a hard engineering solution to the erosion problem might be unacceptable to Vancouver residents. We have used conventional photogrammetry, structures from motion, thermal imaging, and terrestrial full waveform laser scanning to provide base-line spatial data for the most rapidly eroding section of the cliff. Here, we present some of our results and discuss the challenges that we faced in characterizing this large soil slope.

  9. Solute transport in eroded and rehabilitated prairie landforms. 1. Nonreactive solute.

    PubMed

    Papiernik, Sharon K; Koskinen, William C; Yates, Scott R

    2009-08-26

    Information regarding solute and water transport as affected by soil properties, topography, and climatic conditions is required to improve and validate transport models. This study evaluated the dissipation of bromide applied to the soil surface in the fall and spring to undisturbed (eroded) and rehabilitated landforms, in which topsoil was moved from depositional areas to the eroded upper slope. Despite large changes in soil properties, the amount and center of mass of bromide remaining in the top 1 m of soil was the same in undisturbed and rehabilitated plots. Approximately 60% of the fall-applied bromide was lost during the winter and early spring, presumably due to leaching and runoff. The center of mass of spring-applied bromide remained at depths of <30 cm. At the end of the experiment, 33% of the spring-applied bromide was detected in soil and 56% in corn plants. These results suggest that little bromide was leached out of the root zone in the spring and that plant uptake was a major route of bromide dissipation during the growing season. PMID:19653694

  10. Solute transport in eroded and rehabilitated prairie landforms. 2. Reactive solute.

    PubMed

    Papiernik, Sharon K; Koskinen, William C; Yates, Scott R

    2009-08-26

    The impact of varying soil, landscape, and climate conditions on the off-site transport of pesticides must be determined to develop improved pesticide management practices. This study quantified the rate of S-metolachlor dissipation after fall and spring application in eroded and rehabilitated landforms in which topsoil was moved from the lower slope to the upper slope. Fall-applied metolachlor provided no control of annual grasses because approximately 80% was removed from the root zone during the winter and early spring, presumably by leaching and runoff. S-Metolachlor dissipated in the spring with a DT(50) of 24-29 days. These results suggest that fall-applied metolachlor may not provide economic weed control and presents an increased risk of water contamination. Although landscape position and bulk soil movement within the landform had a large impact on soil properties, no significant differences in metolachlor dissipation between different landscape positions and between eroded and rehabilitated landforms were observed. PMID:19653695

  11. Persistence of soil organic matter in eroding versus depositional landform positions

    USGS Publications Warehouse

    Berhe, Asmeret Asefaw; Harden, Jennifer W.; Torn, Margaret S.; Kleber, Markus; Burton, Sarah D.; Harte, John

    2012-01-01

    Soil organic matter (SOM) processes in dynamic landscapes are strongly influenced by soil erosion and sedimentation. We determined the contribution of physical isolation of organic matter (OM) inside aggregates, chemical interaction of OM with soil minerals, and molecular structure of SOM in controlling storage and persistence of SOM in different types of eroding and depositional landform positions. By combining density fractionation with elemental and spectroscopic analyses, we showed that SOM in depositional settings is less transformed and better preserved than SOM in eroding landform positions. However, which environmental factors exert primary control on storage and persistence of SOM depended on the nature of the landform position considered. In an annual grassland watershed, protection of SOM by physical isolation inside aggregates and chemical association of organic matter (complexation) with soil minerals, as assessed by correlation with radiocarbon concentration, were more effective in the poorly drained, lowest-lying depositional landform positions, compared to well-drained landform positions in the upper parts of the watershed. Results of this study demonstrated that processes of soil erosion and deposition are important mechanisms of long-term OM stabilization.

  12. Sediment erodability in sediment transport modelling: Can we account for biota effects?

    NASA Astrophysics Data System (ADS)

    Le Hir, P.; Monbet, Y.; Orvain, F.

    2007-05-01

    Sediment erosion results from hydrodynamic forcing, represented by the bottom shear stress (BSS), and from the erodability of the sediment, defined by the critical erosion shear stress and the erosion rate. Abundant literature has dealt with the effects of biological components on sediment erodability and concluded that sediment processes are highly sensitive to the biota. However, very few sediment transport models account for these effects. We provide some background on the computation of BSS, and on the classical erosion laws for fine sand and mud, followed by a brief review of biota effects with the aim of quantifying the latter into generic formulations, where applicable. The effects of macrophytes, microphytobenthos, and macrofauna are considered in succession. Marine vegetation enhances the bottom dissipation of current energy, but also reduces shear stress at the sediment-water interface, which can be significant when the shoot density is high. The microphytobenthos and secreted extracellular polymeric substances (EPS) stabilise the sediment, and an increase of up to a factor of 5 can be assigned to the erosion threshold on muddy beds. However, the consequences with respect to the erosion rate are debatable since, once the protective biofilm is eroded, the underlying sediment probably has the same erosion behaviour as bare sediment. In addition, the development of benthic diatoms tends to be seasonal, so that stabilising effects are likely to be minimal in winter. Macrofaunal effects are characterised by extreme variability. For muddy sediments, destabilisation seems to be the general trend; this can become critical when benthic communities settle on consolidated sediments that would not be eroded if they remained bare. Biodeposition and bioresuspension fluxes are mentioned, for comparison with hydrodynamically induced erosion rates. Unlike the microphytobenthos, epifaunal benthic organisms create local roughness and are likely to change the BSS generated

  13. Soil erosion increases soil microbial activity at the depositional position of eroding slopes

    NASA Astrophysics Data System (ADS)

    Meng, Xu; Cardenas, Laura M.; Donovan, Neil; Zhang, Junling; Murray, Phil; Zhang, Fusuo; Dungait, Jennifer A. J.

    2016-04-01

    Soil erosion is the most widespread form of soil degradation. Estimation of the impact of agricultural soil erosion on global carbon cycle is a topic of scientific debate, with opposing yet similar magnitude estimates of erosion as a net source or sink of atmospheric carbon. The transport and deposition of eroded agricultural soils affects not only the carbon cycle but other nutrient cycles as well. It has been estimated that erosion-induced lateral fluxes of nitrogen (N) and phosphorus (P) could be similar in magnitude to those from fertilizer application and crop removal (Quinton et al., 2010). In particular, the dynamics of soil N in eroding slopes need to be considered because the management of soil N has profound influences on the functioning of soil microorganisms, which are generally considered as the main biotic driver of soil C efflux. Carbon dioxide (CO2) emissions tend to increase in deposition positions of eroded slopes, diminishing the sink potential of eroded soils C (. As the global warming potential of nitrous oxide (N2O) is 310 times relative to that of CO2, the sink potential of agricultural erosion could easily be negated with a small increase in N2O emissions. Therefore, an investigation of the potential emissions of greenhouse gases, and especially N2O from soils affected by agricultural erosion, are required. In the present study, a field experiment was established with contrasting cultivation techniques of a C4 crop (Zea mays; δ13C = -12.2‰) to introduce 13C-enriched SOC to a soil previously cropped with C3 plants (δ13C = -29.3‰). Soils sampled from the top, middle, bottom and foot slope positions along a distinct erosion pathway were analyzed using 13C-phospholipid fatty acid (PLFA) analysis and incubated to investigate the responses of microorganisms and associated potential emissions of greenhouse gases (GHG). The total C and N contents were greatest in soils at the top slope position, whereas soil mineral N (NO3--N and NH4+-N

  14. Granular flows on erodible layers: type and evolution of flow and deposit structures

    NASA Astrophysics Data System (ADS)

    Crosta, G.; De Blasio, F.; De Caro, M.; Volpi, G.; Frattini, P.

    2012-04-01

    The interaction of a fast moving landslide mass with the basal layer over which movement takes place has been discussed in previous contributions. Nevertheless, the evolution of the structures within the moving mass and the erodible layer are still to be described in detail (Hungr and Evans, 2004; Crosta et al., 1992, 2006, 2009, 2011; Dufresne et al., 2010; Mangeney et al., 2010) and modeling results (Crosta et al., 2006, 2009, 2011; Mangeney et al., 2010). We present some of the results from a campaign of laboratory experiments aimed at studying the evolution of a granular flow at the impact with and during the successive spreading over a cohesionless erodible layer. We performed these test to study the processes and to collect data and evidences to compare them with the results of numerical simulations and to verify capabilities of numerical codes. The laboratory setup consists of an inclined slope and an horizontal sector where release and transport, and deposition take place, respectively. Materials used for the tests are: a uniform rounded siliceous sand (Hostun sand; 0.125-0.5 mm) commonly adopted in lab tests because free of scale effects, and a gravel made of angular elements (12 mm in ave. size). Both the materials have been tested in dry conditions. Different slope angles have been tested (40, 45, 50, 55, 50, 66°) as well as different thicknesses of the erodible layer (0, 0.5, 1, 2 cm) and volumes of the released material (1.5, 3, 5, 9.6 liters). Tests have been monitored by means of a high speed camera and the pre- and post-failure geometries have been surveyed by means of a laser scanner. Deposit description allowed also the computation of volumes and the characterization of the different structures developed and frozen into the deposit. Experiments allowed us to observe the extreme processes occurring during the movement and the mise en place of the deposits. In particular, we observe the formation of a clear wave-like feature developing during the

  15. Stable isotopes and chemical composition at different spatial scales indicate sink function of eroded OC in a tropical catchment

    NASA Astrophysics Data System (ADS)

    Chaplot, V.; Rumpel, C.; Fontaine, S.; Bouahom, B.; Valentin, C.

    2009-04-01

    Our objective was to evaluate the fate of eroded carbon at landscape level in a steep slope area of the Mekong basin submitted to traditional slash-and-burn (SAB) agriculture. We monitored carbon erosion at different spatial scales ranging from 1m² (micro-plot level) installed within a hillslope to 1×107 m² (watershed). Samples were taken throughout the 2003 rainy season, in order to quantitatively assess the fate of eroded OC. Laboratory analysis of the chemical composition of eroded OC by analysis for its elemental, istotopic (13C, 15N, 14C) and bulk chemical composition were performed to assess potential microbial decomposition of eroded sediment during transport and sedimentation. Our data show, that 92.7% of eroded OC were sedimented at a distance lower that 1.5m from its source. Analysis of the composition of eroded organic matter at different scales showed a significant decrease of the C/N ratio and an enrichment of 13C and 15N isotopes, which occurred within the hillslope and in first order reaches. These changes were interpreted as resulting from OC decomposition and used to assess the CO2 emissions, which might have occurred during the erosion process. Our results indicate, that within the hillslope, potential CO2 emissions with 0.43 gCm-2y-1 would be 3.3 times higher than the OC exports by water erosion but represented about 10% only of the OC deposited. Potential CO2 emissions during the transport from the hillslope to the watershed outlet would represent 14% of total eroded OC. Based on these results, we suggest that erosion induced OC sequestration amounts to 43 gCm-2y-1 in the hillslope and, 33 gCm-2y-1 at the watershed level.

  16. The effect of a desensitizer and CO2 laser irradiation on bond performance between eroded dentin and resin composite

    PubMed Central

    Ding, Meng; Shin, Sang-Wan; Kim, Min-Soo

    2014-01-01

    PURPOSE This study was aimed to evaluate effect of the desensitizing pretreatments on the micro-tensile bond strengths (µTBS) to eroded dentin and sound dentin. MATERIALS AND METHODS Forty-two extracted molars were prepared to form a flat dentin surface, and then they were divided into two groups. Group I was stored in distilled water while group II was subjected to a pH cycling. Each group was then subdivided into three subgroups according to desensitizing pretreatment used: a) pretreatment with desensitizer (Gluma); b) pretreatment with CO2 Laser (Ultra Dream Pluse); c) without any pretreatment. All prepared surfaces were bonded with Single Bond 2 and built up with resin composite (Filtek Z250). The micro-tensile bond test was performed. Fracture modes were evaluated by stereomicroscopy. Pretreated surfaces and bonded interfaces were characterized by scanning electron microscope (SEM). The data obtained was analyzed by two-way ANOVA (α=0.05). RESULTS For both sound and eroded dentin, samples treated with desensitizer showed the greatest µTBS, followed by samples without any treatment. And samples treated with CO2 laser showed the lowest µTBS. SEM study indicated that teeth with eroded dentin appeared prone to debonding, as demonstrated by existence of large gaps between adhesive layers and dentin. CONCLUSION Pretreatment with Gluma increased the µTBS of Single Bond 2 for eroded and sound teeth. CO2 laser irradiation weakened bond performance for sound teeth but had no effect on eroded teeth. PMID:25006379

  17. Variation of Basal EROD Activities in Ten Passerine Bird Species – Relationships with Diet and Migration Status

    PubMed Central

    Rainio, Miia J.; Kanerva, Mirella; Wahlberg, Niklas; Nikinmaa, Mikko; Eeva, Tapio

    2012-01-01

    Inter-specific differences in animal defence mechanisms against toxic substances are currently poorly understood. The ethoxyresorufin-O-deethylase (EROD) enzyme plays an important role in defence against toxic chemicals in a wide variety of animals, and it is an important biomarker for environmental contamination. We compared basal hepatic EROD activity levels among ten passerine species to see if there is inter-specific variation in enzyme activity, especially in relation to their diet and migration status. Migratory insectivores showed higher EROD activity compared to granivores. We hypothesize that the variable invertebrate diet of migratory insectivores contains a wider range of natural toxins than the narrower diet of granivores. This may have affected the evolution of mixed function oxidases (MFO) system and enzyme activities. We further tested whether metabolic rates or relative liver size were associated with the variation in detoxification capacity. We found no association between EROD activity and relative (per mass unit) basal metabolic rate (BMR). Instead, EROD activity and relative liver mass (% of body mass) correlated positively, suggesting that a proportionally large liver also functions efficiently. Our results suggest that granivores and non-migratory birds may be more vulnerable to environmental contaminants than insectivores and migratory birds. The diet and migration status, however, are phylogenetically strongly connected to each other, and their roles cannot be fully separated in our analysis with only ten passerine species. PMID:22479477

  18. Improving dust emission characterization in dust models using dynamic high-resolution geomorphic erodibility map

    NASA Astrophysics Data System (ADS)

    Parajuli, S. P.; Yang, Z.; Kocurek, G.

    2013-12-01

    Dust is known to affect the earth radiation budget, biogeochemical cycle, precipitation, human health and visibility. Despite the increased research effort, dust emission modeling remains challenging because dust emission is affected by complex geomorphological processes. Existing dust models overestimate dust emission and rely on tuning and a static erodibility factor in order to make simulated results comparable to remote sensing and ground-based observations. In most of current models, dust emission is expressed in terms of threshold friction speed, which ultimately depends mainly upon the percentage clay content and soil moisture. Unfortunately, due to the unavailability of accurate and high resolution input data of the clay content and soil moisture, estimated threshold friction speed commonly does not represent the variability in field condition. In this work, we attempt to improve dust emission characterization by developing a high resolution geomorphic map of the Middle East and North Africa (MENA), which is responsible for more than 50% of global dust emission. We develop this geomorphic map by visually examining high resolution satellite images obtained from Google Earth Pro and ESRI base map. Albeit subjective, our technique is more reliable compared to automatic image classification technique because we incorporate knowledge of geological/geographical setting in identifying dust sources. We hypothesize that the erodibility is unique for different geomorphic landforms and that it can be quantified by the correlation between observed wind speed and satellite retrieved aerosol optical depth (AOD). We classify the study area into several key geomorphological categories with respect to their dust emission potential. Then we quantify their dust emission potential using the correlation between observed wind speed and satellite retrieved AOD. The dynamic, high-resolution geomorphic erodibility map thus prepared will help to reduce the uncertainty in current

  19. The effects of erodent particle size and composition on the erosion of chromium carbide based coatings

    SciTech Connect

    Walsh, P.N.; Quets, J.M.; Tucker, R.C. Jr.

    1994-12-31

    A number of studies and field experience have demonstrated the efficacy of use of chromium carbide based coatings on steam turbine components to reduce the effects of solid particle erosion. To optimize the performance of these coatings, a cost effective laboratory test is needed to facilitate the choice of coating composition, morphology, and deposition method. A variety of test types and test parameters have been reported with varying relative rankings of the various coatings evaluated. A critical review of past work has been made, with new data added for clarification. The particle size of the erodent used as well as its composition has been shown to be of particular importance. A correlation between field experience and selected laboratory test parameters then facilitates the optimum choice of coatings.

  20. Loess Plateau check dams can potentially sequester eroded soil organic carbon

    NASA Astrophysics Data System (ADS)

    Zhang, Haicheng; Liu, Shuguang; Yuan, Wenping; Dong, Wenjie; Xia, Jiangzhou; Cao, Yaojun; Jia, Yanwei

    2016-06-01

    Check dams are special soil and water conservation structures in the Loess Plateau, China. They play an important role in intercepting sediments and soil organic carbon (SOC). However, the decomposition of intercepted SOC and the environmental regulations at check dams have not been investigated. We conducted several paired field experiments at both check dams and slope lands in the Yanhe Watershed of the Loess Plateau to examine the characteristics of SOC decomposition at check dams. On average, the SOC mineralization rate in slope lands was approximately three times higher than in check dams. Increased soil moisture and compaction in check dams can constrain carbon mineralization by limiting the oxygen availability of SOC and can isolate substrate carbon from heterotrophic microorganisms. Our results indicate that check dams display a considerable potential for eroded SOC sequestration via reducing the soil respiration rate and highlight the important implications of lateral carbon redistribution and human engineering projects when estimating regional or global ecosystem carbon cycles.

  1. Seasonal Variation of Groundwater Quality in Erode District, Tamil Nadu, India.

    PubMed

    Kavidha, R; Elangovan, K

    2014-07-01

    In recent years, the recurring environmental issues regarding hazardous waste, global climate change, stratospheric ozone depletion, groundwater contamination, disaster mitigation and removal of pollutant have become the focus of environmental attention. In the management of water resources, quality of water is just as important as its quantity. In order to assess the quality and/or suitability of groundwater for drinking and irrigation in Erode District, 144 water samples each in post-monsoon and pre-monsoon during the year 2007 were collected and analyzed for various parameters. These parameters were compared with IS: 10500-1991 drinking water standards. Out of 144 samples, 29 samples exceeded the permissible limit for both the monsoons, 71 samples were within the permissible limit for both the monsoons and the remaining samples exceeded the permissible limit for any one of the monsoon. During both monsoons, except some samples, most of the samples were suitable for drinking and irrigation.

  2. Seasonal Variation of Groundwater Quality in Erode District, Tamil Nadu, India.

    PubMed

    Kavidha, R; Elangovan, K

    2014-07-01

    In recent years, the recurring environmental issues regarding hazardous waste, global climate change, stratospheric ozone depletion, groundwater contamination, disaster mitigation and removal of pollutant have become the focus of environmental attention. In the management of water resources, quality of water is just as important as its quantity. In order to assess the quality and/or suitability of groundwater for drinking and irrigation in Erode District, 144 water samples each in post-monsoon and pre-monsoon during the year 2007 were collected and analyzed for various parameters. These parameters were compared with IS: 10500-1991 drinking water standards. Out of 144 samples, 29 samples exceeded the permissible limit for both the monsoons, 71 samples were within the permissible limit for both the monsoons and the remaining samples exceeded the permissible limit for any one of the monsoon. During both monsoons, except some samples, most of the samples were suitable for drinking and irrigation. PMID:26563080

  3. EROD activity and genotoxicity in the seabob shrimp Xiphopenaeus kroyeri exposed to benzo[a]pyrene (BaP) concentrations.

    PubMed

    da Silva Rocha, Arthur José; Gomes, Vicente; Rocha Passos, Maria José de Arruda Campos; Hasue, Fabio Matsu; Alves Santos, Thaís Cruz; Bícego, Márcia Caruso; Taniguchi, Satie; Van Ngan, Phan

    2012-11-01

    Seabob shrimp Xiphopenaeus kroyeri is a marine species that lives in shallow waters of coastal environments, often impacted by polycyclic aromatic hydrocarbons (PAH) pollution. In the present study, seabob shrimp were exposed for 96 h to benzo[a]pyrene (BaP) at the nominal concentrations of 100, 200, 400 and 800 microg-L(-1). Animals of the control groups were exposed either to clean water or to the BaP-carrier (DMSO). At the end of the exposures, muscle tissues were sampled for BaP uptake assessment and hepatopancreas and hemolymph for EROD enzyme activity and hemocytes DNA damage, respectively. EROD activity and DNA damage increased significantly as a function of BaP exposure concentrations. Significant correlations between BaP uptake and both EROD activity and DNA damage suggest that they can be used as suitable tools for integrated levels of study on the biomarkers of PAH exposure.

  4. Mathematical techniques to characterize nitrogen isotherms from eroded sediments under conventional tillage and no tillage

    NASA Astrophysics Data System (ADS)

    Marinho, M. D.; Paz-Ferreiro, J.

    2011-12-01

    Soil specific surface area (SSA) is one of the most important soil properties as it affects chemical reactivity, cation exchange capacity and, in general, nutrient holding capacity. The SSA of a soil mainly depends on texture, clay type and organic matter content, which in turn are factors affecting the erosion potential. An important consideration in the link between soil erosion and nutrient transfer to waters is the well-documented relation between SSA (or particle size distribution) and nutrient losses. Because, sediment erosion and transport processes are particle size dependent, they influence also SSA. Characterization of both, soil nitrogen adsorption and desorption isotherms by monofractal and multifractal analysis has been demonstrated to be an useful tool, which allows a better understanding of the organization of the soil colloidal complex. Here, we report measures of nitrogen isotherm in sediments produced under three different management histories and we characterize them by various mathematical techniques including fractal and multifractal analysis. Soil and water losses from an Oxisol were evaluated under natural rain, at the experimental station of UNICAMP/ FEAGRI, Campinas, SP, Brazil. Experimental plots were 20 m x 30 m (i.e. 600 m2) and the management systems compared were no-tillage and two different conventional tillage techniques. Specific surface area determined by the classical BET method was significantly lower in sediments eroded from the no-tilled than from the tilled plots. The scaling properties of both nitrogen adsorption and desorption isotherms from all the studied sediment samples could be fitted reasonably well with multifractal models. Various fractal and multifractal parameters obtained from the adsorption and desorption characteristics also were useful to differentiate the impact of tillage treatment on the adsorption and desorption characteristics of the eroded sediments. Reasons for such differences have been already explored.

  5. Topographic roughness as a signature of the emergence of bedrock in eroding landscapes

    NASA Astrophysics Data System (ADS)

    Milodowski, D. T.; Mudd, S. M.; Mitchard, E. T. A.

    2015-10-01

    Rock is exposed at the Earth surface when rates of erosion locally exceed rates of soil production. The thinning of soils and emergence of bedrock has implications spanning geomorphology, ecology and hydrology. Soil-mantled hillslopes are typically shaped by diffusion-like sediment transport processes that act to smooth topography through time, generating the familiar smooth, convex hillslope profiles that are common in low relief landscapes. Other processes, however, can roughen the landscape. Bedrock emergence can produce rough terrain; in this contribution we exploit the contrast between rough patches of bedrock outcrop and smooth, diffusion-dominated soil to detect bedrock outcrops. Specifically, we demonstrate that the local variability of surface normal vectors, measured from 1 m resolution airborne LiDAR data, can be used as a topographic signature to identify areas within landscapes where rock exposure is present. We then use this roughness metric to investigate the transition from soil-mantled to bedrock hillslopes as erosion rates increase in two transient landscapes, Bald Rock Basin, which drains into the Middle Fork Feather River, California, and Harrington Creek, a tributary of the Salmon River, Idaho. Rather than being abrupt, as predicted by traditional soil production models, in both cases the transition from fully soil-mantled to bedrock hillslopes is gradual and spatially heterogeneous, with rapidly eroding hillslopes supporting a patchwork of bedrock and soil that is well documented by changes in topographic roughness, highlighting the utility of this metric for testing hypotheses concerning the emergence of bedrock and adding to a growing body of evidence that indicates the persistence of partial soil mantles in steep, rapidly eroding landscapes.

  6. Crop Performance and Soil Properties in Two Artificially-Eroded Soils in North-Central Alberta

    SciTech Connect

    Izaurralde, R Cesar C.; Malhi, S. S.; Nyborg, M.; Solberg, E. D.; Quiroga Jakas, Maria C.

    2006-09-01

    Field experiments were conducted from 1991 to 1995 at Josephburg (Orthic Black Chernozem, Typic Cryoboroll) and Cooking Lake (Orthic Gray Luvisol, Typic Cryoboralf), Alberta, to determine impact of topsoil removal on selected soil properties, N-mineralization potential and crop yield, and effectiveness of various amendments for restoring the productivity of eroded soils. The simulated-erosion levels were established in the autumn of 1990 by removing 20 cm topsoil in 5-cm depth increments. The four amendments were: control, addition of 5 cm of topsoil, fertilizers to supply 100 kg N ha-1 and 20 kg P ha-1, and cattle manure at 75 Mg ha-1. Topsoil and manure were applied once in the autumn of 1990, while fertilizers were applied annually from 1991 to 1995. Available N and P, total C, N and P, and N-mineralization potential decreased, while bulk density increased with increasing depth of topsoil removal. Tiller number, plant height, spike density, thousand kernel weight, and leaf area index decreased with simulated erosion. Grain yield reductions due to simulated soil erosion were either linear or curvilinear functions of nutrient removal. Application of N and P fertilizers and manure improved grain yield and reduced the impact of yield loss due to erosion. Return of 5 cm of topsoil also increased grain yield, but to a lesser extent than manure or fertilizers. Grain yields were maximized when fertilizers were also applied to organic amendment treatments. In conclusion, the findings suggest the importance of integrated use of organic amendments and chemical fertilizers for best crop yields on severely-eroded soils.

  7. Measuring Carbon and Nitrogen Eroded From Burned Forests In The Western U.S

    NASA Astrophysics Data System (ADS)

    Pierson, D. N.; Robichaud, P. R.; Rhoades, C.

    2013-12-01

    Post-wildfire upland landscapes and downstream aquatic resources are influenced by carbon (C) and nitrogen (N) losses due to soil erosion. As opposed to bulk soil erosion, few studies have quantified C and N losses after severe wildfire. We measured erosion of C and N for four to six years following eight wildfires in the western U.S. and compared C and N losses from untreated, burned hillslopes and small catchments with those from adjacent areas that received various erosion mitigation treatments. Losses of C, N and sediment were greatest the first two years and declined in subsequent years. Cumulative losses from untreated, burned areas were 16 - 4,700 kg C/ha and 0.7 - 185 kg N/ha over the study period. Individual storm events were responsible for > 50% of the total C and N lost. Across wildfire locations, median sediment C and N concentration ranged from 0.11 - 0.36 %N and 2.3 - 9.8 %C. Post-fire erosion control treatments reduced C, N and sediment losses by 65-75% compared to untreated areas and generally increased the concentrations of C and N in eroded material. The total C and N lost in post-fire erosion was < 20% of the estimated amount lost from organic and mineral soil layers during combustion and < 5% of the estimated amount remaining in mineral soils after combustion. The additional N lost with soil erosion is unlikely to impair the productivity of recovering forests, but the eroded N may have consequences on downstream water quality and aquatic habitat.

  8. Missing-Presumed Eroded: Holocene Sedimentation Patterns in Seneca Lake, NY

    NASA Astrophysics Data System (ADS)

    Loddengaard, K.; Curtin, T. M.

    2006-12-01

    The Finger Lakes of New York underwent a significant change in climate during the transition from the Hypsithermal to the Neoglacial at ~5 ka. To determine the effects of changes in climate on sedimentation patterns in the northern region of Seneca Lake, NY, we analyzed three cores that were collected along a shallow to deep water transect. Analyses of magnetic susceptibility, organic matter and carbonate content, fossil content, and grain size at a 1-cm interval were used to correlate cores, identify periods of erosion or non- deposition and assess the relative truncation of the Holocene sediment record. The stratigraphy and sedimentology of the cores indicate the lake contains a spatially and temporally discontinuous sediment record. Preliminary results indicate that the early to mid-Holocene sediment record was preferentially eroded in the deepwater cores, between 20 and 50 m water depth. At the deepwater sites, there is a gap in the sediment record that spans between ~12 and ~5 ka. Conversely, the late Holocene record is more complete in the deepwater cores than in the shallow water cores (12-20 m water depth). This data suggests a significant change on the controls and location of erosion and deposition in the lake during the Holocene. We hypothesize that the early to mid-Holocene sediment may have been eroded by strong internal seiches during stormy conditions that were initiated by cooler temperatures and a change in the position of the jet stream during the Hypsithermal-Neoglacial transition. Erosion occurred primarily in shallow water sites (<~30 m) during the Neoglacial, perhaps as a result of a change in the number and frequency of storms or strength of the internal seiche.

  9. Restoration of drastically eroded land using coal fly ash and poultry biosolid.

    PubMed

    Punshon, Tracy; Adriano, Domy C; Weber, John T

    2002-09-16

    A 3-year field study was conducted at a 12 ha soil-borrow area adjacent to the Columbia Metropolitan Airport, South Carolina to investigate the restorative effects of co-application of coal fly ash (FA) and a poultry biosolid (PB). FA was applied at 0, 22, 280, 560 and 1120 Mg (tonne) ha(-1), and PB at 5 and 10 Mg ha(-1). The area was seeded with erosion-control species Atlantic Coastal panic grass (Panicum amarum var amarum L.), sericea (Lespedeza cuneata var. appalow [Dumont] G. Don.) and weeping love grass (Eragrostis curvula Wolf.). Plant biomass and elemental composition were analyzed in sequential harvests. Soil and groundwater quality characteristics including pH, EC and elemental composition were also monitored throughout the study. In addition, the effect of amendments on the water holding capacity and bulk density of the soil was investigated. Amendment addition significantly increased plant biomass production by a maximum of 26% using 1120 Mg ha(-1) FA and 10 Mg ha(-1) PB. Application of the highest rate of FA significantly increased the plant tissue concentrations of Mn, As, Se and B. Soil pH was initially increased from 4.6 to 6.1 by amendments. Soil salinity was increased in the initial year only. Amended soils had higher concentrations of Ca, Mg, P and K, higher organic matter content and water holding capacity than unamended soil. Concentrations of plant-essential trace elements (B, Cu and Zn) that were marginally deficient in the unamended eroded soil increased to within typical soil concentrations following amendment with FA and PB. Groundwater quality was unaffected throughout the study. The co-application of FA and PB successfully promoted the revegetation of the eroded borrow area with no apparent adverse environmental side effects.

  10. Sediment TCDD-EQs and EROD and MROD activities in Ranid frogs from agricultural and nonagricultural sites in Michigan (USA).

    PubMed

    Murphy, M B; Hecker, M; Coady, K K; Tompsett, A R; Jones, P D; Newsted, J L; Wong, H L; du Preez, L H; Solomon, K R; Carr, J A; Smith, E E; Kendall, R J; Van der Kraak, G; Giesy, J P

    2006-10-01

    In vitro studies have demonstrated atrazine-mediated induction of 7-ethoxyresorufin O-deethylase (EROD) activity. EROD is an enzyme active in the metabolism of many compounds, including many xenobiotics. These studies have suggested that atrazine may affect reproductive function by altering steroid metabolism. The goal of this study was to determine whether relationships could be detected between measured atrazine concentrations in surface waters and the liver-somatic index (LSI) and EROD and 7-methoxyresorufin O-deethylase (MROD) activities in the livers of ranid frogs. In addition, sediment dioxin toxic equivalents (TCDD-EQs) were determined using the H4IIE-luc cell bioassay. Adult and juvenile green frogs (Rana clamitans), bullfrogs (R. catesbeiana), and Northern leopard frogs (R. pipiens) were collected from areas with extensive corn cultivation and areas where there was little agricultural activity in south central Michigan in the summer of 2003. Atrazine concentrations at nonagricultural sites ranged from less than the limit of quantification (0.17 microg atrazine/L) to 0.23 microg atrazine/L and did not exceed 1.2 microg atrazine/L at agricultural sites. Sediment TCDD-EQs were measurable only at one agricultural site. Of the measured parameters, only LSI values in adult male frogs differed significantly between agricultural and nonagricultural sites, with greater values observed at agricultural sites. In green frogs, EROD and MROD activities were measurable in both adult and juvenile frogs and were similar among sites. Median EROD activities ranged from 13 to 21 pmol/min/mg protein in adult male green frogs and from 5 to 13 pmol/min/mg protein in adult female green frogs. Juvenile frogs had greater EROD and MROD activities than adult frogs. Bullfrogs and leopard frogs had greater activities than did green frogs. Atrazine concentrations were significantly and negatively correlated with MROD activity in adult male green frogs (Spearman R = -0.800). LSI and

  11. Evolution of potentially eroding events along the northern coast of the Iberian Peninsula

    NASA Astrophysics Data System (ADS)

    Rasilla Álvarez, D.; García Codrón, J. C.

    2009-09-01

    The anthropogenic global warming is expected to result in a rise in sea-level, accompanied by changes in extreme climate events, such as the frequency and intensity of storms. Such scenario would result in an acceleration of coastal erosion. The aim of the present study is to assess the temporal evolution of potentially eroding events along the northern coast of the Iberian Peninsula during the second half of the 20th century, and to investigate changes in forcing processes such as the frequency and magnitude of storm surges and high wave events. To characterize the potentially eroding events, the total elevation of the water level was selected, being calculated as the sum of the contributions of the average water level, wave run up and the storm surges. Potentially eroding events were identified and quantified following a two-step procedure. Through the first step the potential flood induced by a given storm was estimated by simulating its effects on a theoretical beach profile (intermediate) using an empirical parameterization for extreme run-up approach. The second step consisted on characterizing the maximum storm surge registered during a storm. Those parameters were calculated from hindcasted data (storm surge, wave heights and period, wind speed and direction), retrieved from the SIMAR-44 database (Puertos del Estado), and validated against actual tide gauge measurements and buoy data (RedMar and RedExt networks). Analyses of total water levels showed a long term increase since 1958, resulting from the increase of mean sea level; conversely, a reduction of the frequency and the intensity of the storm events were deduced from the analysis of meteorological records. Since the impact of the storms on macro- and meso- tidal coast closely depend on the tides, a storm impact index was computed taking into account the storm surge magnitude, the wave heights and time duration during which a predefined threshold was exceeded by the sea level. The results are

  12. Interrill Erodibility of P and C on conventially and organically farmed Devon soils

    NASA Astrophysics Data System (ADS)

    Kuhn, N. J.

    2012-04-01

    Soil erosion can have significant off-site effects on water quality and thus human and habitat health. Apart from sedimentation, the transfer of nutrients, both dissolved and particulate, is a major concern. The particulate transfer of nutrients from agricultural land can occur either by rill or interrill erosion. Rill erosion is non-selective and affects only a limited extent of agricultural land. Interrill processes such as crusting, splash and raindrop-impacted wash, on the other hand, act on all cropland and affect the quality of the water from all areas generating runoff. A significant amount of phosphorus (P) is contained in the surface soil layer transformed by interrill processes annually. In the EU, the P content of a crusted (2 mm) surface layer corresponds to 4 to 40 kg ha-1 of P on arable land (1.094 mil km2). Therefore, the role of interrill processes and erosion for regional nutrient cycling requires close attention. Interrill erosion is a complex phenomenon, involving the detachment, transport and deposition of soil particles by raindrop impacted flow. Resistance to interrill erosion varies between soils depending on their physical, chemical and mineralogical properties. In addition, significant changes in soil resistance to interrill erosion occur during storms as a result of changes in surface roughness, cohesion and particle size. As a consequence, erosion on interrill areas is selective, moving the most easily detached small and/or light soil particles which are often enriched in clay, P and organic C. Commonly, the risk of erosion associated with organically farmed soils is lower than those farmed in a conventional way. This is attributed to greater aggregate stability and thus greater infiltration and lower erodibility. Erosion of nutrients on organically farmed soils is therefore considered to be reduced by the same order of magnitude than the amount of eroded soil compared to conventionally farmed soils. However, the selective nature of

  13. Mineral-organic matter associations in eroding hillslopes: findings from headwater catchments in the Southern Sierra Nevada (Invited)

    NASA Astrophysics Data System (ADS)

    Berhe, A.; Stacy, E.; McCorkle, E. P.; Johnson, D. W.; Hunsaker, C. T.; Hart, S. C.

    2013-12-01

    Mineral-organic matter (OM) associations--physical encapsulation of OM inside soil aggregates and chemical bonding and complexation of organic functional groups with soil minerals--determine the proportion of soil organic matter (SOM) that is redistributed and mineralized during and after erosional transport of sediments downhill, as well as the stability of the eroded SOM post-deposition. The susceptibility of SOM to decomposition and its stabilization mechanisms can change during and after erosion as a result of: aggregate breakdown or detachment due to kinetic energy of raindrops and/or shearing during lateral transport, and reconfiguration of mineral-OM associations through formation of new and strengthening of existing mineral-OM associations in depositional environments that are enriched in carbon (C) and reactive soil minerals. The goal of this study was to determine how concentration, nature and distribution of SOM in soil fractions vary between eroding slopes and sediments exported from eroding catchments. Free organic particles exported from eroding watersheds typically represent <30% of total carbon mobilized by erosion, compared to <20% mobilized as aggregate protected C and <30% as C complexed with Fe and Al oxides. Our results show that there is large variability in nature of exported material across eight headwater catchments that is not directly related to watershed size or climatic variability. In addition, we quantified the rate at which different OM fractions are preferentially transported and can be potentially lost through decomposition during lateral transport.

  14. Fine gravel controls hydrologic and erodibility responses to trampling disturbance for coarse-textured soils with weak cyanobacterial crusts.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We compared short-term effects of lug-soled boot trampling disturbance on water infiltration and soil erodibility on coarse-textured soils covered by a mixture of fine gravel and coarse sand over weak cyanobacterially-dominated biological soil crusts. Trampling significantly reduced final infiltrati...

  15. Chromosomal damage and EROD induction in tree swallows (Tachycineta bicolor) along the Upper Mississippi River, Minnesota, USA.

    PubMed

    Bigorgne, Emilie; Custer, Thomas W; Dummer, Paul M; Erickson, Richard A; Karouna-Renier, Natalie; Schultz, Sandra; Custer, Christine M; Thogmartin, Wayne E; Matson, Cole W

    2015-07-01

    The health of tree swallows, Tachycineta bicolor, on the Upper Mississippi River (UMR) was assessed in 2010 and 2011 using biomarkers at six sites downriver of Minneapolis/St. Paul, MN metropolitan area, a tributary into the UMR, and a nearby lake. Chromosomal damage was evaluated in nestling blood by measuring the coefficient of variation of DNA content (DNA CV) using flow cytometry. Cytochrome P450 1A activity in nestling liver was measured using the ethoxyresorufin-O-dealkylase (EROD) assay, and oxidative stress was estimated in nestling livers via determination of thiobarbituric acid reacting substances (TBARS), reduced glutathione (GSH), oxidized glutathione (GSSG), the ratio GSSG/GSH, total sulfhydryl, and protein bound sulfhydryl (PBSH). A multilevel regression model (DNA CV) and simple regressions (EROD and oxidative stress) were used to evaluate biomarker responses for each location. Chromosomal damage was significantly elevated at two sites on the UMR (Pigs Eye and Pool 2) relative to the Green Mountain Lake reference site, while the induction of EROD activity was only observed at Pigs Eye. No measures of oxidative stress differed among sites. Multivariate analysis confirmed an increased DNA CV at Pigs Eye and Pool 2, and elevated EROD activity at Pigs Eye. These results suggest that the health of tree swallows has been altered at the DNA level at Pigs Eye and Pool 2 sites, and at the physiological level at Pigs Eye site only.

  16. PAH metabolites, GST and EROD in European eel (Anguilla anguilla) as possible indicators for eel habitat quality in German rivers.

    PubMed

    Kammann, Ulrike; Brinkmann, Markus; Freese, Marko; Pohlmann, Jan-Dag; Stoffels, Sandra; Hollert, Henner; Hanel, Reinhold

    2014-02-01

    The stock of the European eel (Anguilla anguilla L.) continues to decline and has reached a new minimum in 2011. Poor health status of the spawners due to organic contaminants is one of the possible causes for this dramatic situation. Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous contaminants, which are rapidly metabolized in vertebrates. EROD (ethoxyresorufin-O-deethylase) and GST (glutathione-S-transferase) are two enzymes involved in PAH detoxification in fish. In this study, PAH metabolites as well as EROD and GST activity in a large, comprising dataset of more than 260 migratory and pre-migratory eels from five large German river basin districts were used to describe PAH exposure and its metabolism as possible indicators for the habitat quality for eels. Eel from the river Elbe appear to be moderately contaminated with PAH. Highest mean values of PAH metabolites were analysed in fish from the river Rhine. However, the results suggest that contaminants such as PAH are metabolized in the fish and may have contributed to EROD activity in eels caught from the Elbe estuary to 600 km upstream. Since the eel's onset of cessation of feeding is closely linked to maturation and migration, we propose bile pigments as new indicators contributing to identify the proportion of migratory eel, which is crucial information for eel management plans. We showed that PAH metabolites normalized to bile pigments as well as EROD could be used to describe the habitat quality and might be suitable parameters in search for suitable stocking habitats.

  17. Chromosomal damage and EROD induction in tree swallows (Tachycineta bicolor) along the Upper Mississippi River, Minnesota, USA.

    PubMed

    Bigorgne, Emilie; Custer, Thomas W; Dummer, Paul M; Erickson, Richard A; Karouna-Renier, Natalie; Schultz, Sandra; Custer, Christine M; Thogmartin, Wayne E; Matson, Cole W

    2015-07-01

    The health of tree swallows, Tachycineta bicolor, on the Upper Mississippi River (UMR) was assessed in 2010 and 2011 using biomarkers at six sites downriver of Minneapolis/St. Paul, MN metropolitan area, a tributary into the UMR, and a nearby lake. Chromosomal damage was evaluated in nestling blood by measuring the coefficient of variation of DNA content (DNA CV) using flow cytometry. Cytochrome P450 1A activity in nestling liver was measured using the ethoxyresorufin-O-dealkylase (EROD) assay, and oxidative stress was estimated in nestling livers via determination of thiobarbituric acid reacting substances (TBARS), reduced glutathione (GSH), oxidized glutathione (GSSG), the ratio GSSG/GSH, total sulfhydryl, and protein bound sulfhydryl (PBSH). A multilevel regression model (DNA CV) and simple regressions (EROD and oxidative stress) were used to evaluate biomarker responses for each location. Chromosomal damage was significantly elevated at two sites on the UMR (Pigs Eye and Pool 2) relative to the Green Mountain Lake reference site, while the induction of EROD activity was only observed at Pigs Eye. No measures of oxidative stress differed among sites. Multivariate analysis confirmed an increased DNA CV at Pigs Eye and Pool 2, and elevated EROD activity at Pigs Eye. These results suggest that the health of tree swallows has been altered at the DNA level at Pigs Eye and Pool 2 sites, and at the physiological level at Pigs Eye site only. PMID:25777616

  18. Chromosomal damage and EROD induction in tree swallows (Tachycineta bicolor) along the Upper Mississippi River, Minnesota, USA

    USGS Publications Warehouse

    Emilie Bigorgne,; Custer, Thomas W.; Dummer, Paul; Erickson, Richard A.; Karouna, Natalie; Schultz, Sandra; Custer, Christine M.; Thogmartin, Wayne E.; Cole W. Matson,

    2015-01-01

    The health of tree swallows, Tachycineta bicolor, on the Upper Mississippi River (UMR) was assessed in 2010 and 2011 using biomarkers at six sites downriver of Minneapolis/St. Paul, MN metropolitan area, a tributary into the UMR, and a nearby lake. Chromosomal damage was evaluated in nestling blood by measuring the coefficient of variation of DNA content (DNA CV) using flow cytometry. Cytochrome P450 1A activity in nestling liver was measured using the ethoxyresorufin-O-dealkylase (EROD) assay, and oxidative stress was estimated in nestling livers via determination of thiobarbituric acid reacting substances (TBARS), reduced glutathione (GSH), oxidized glutathione (GSSG), the ratio GSSG/GSH, total sulfhydryl, and protein bound sulfhydryl (PBSH). A multilevel regression model (DNA CV) and simple regressions (EROD and oxidative stress) were used to evaluate biomarker responses for each location. Chromosomal damage was significantly elevated at two sites on the UMR (Pigs Eye and Pool 2) relative to the Green Mountain Lake reference site, while the induction of EROD activity was only observed at Pigs Eye. No measures of oxidative stress differed among sites. Multivariate analysis confirmed an increased DNA CV at Pigs Eye and Pool 2, and elevated EROD activity at Pigs Eye. These results suggest that the health of tree swallows has been altered at the DNA level at Pigs Eye and Pool 2 sites, and at the physiological level at Pigs Eye site only.

  19. Metolachlor dissipation following fall and spring application to eroded and rehabilitated landscapes of the US Corn Belt

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A study was conducted to evaluate the effects of landscape position and soil properties on the rate of metolachlor dissipation and weed control efficacy of fall- and spring-applied metolachlor in eroded and rehabilitated landforms in the midwestern United States. Soil-landscape rehabilitation result...

  20. Comparison of soil erodibility factors in USLE, RUSLE2, EPIC and Dg models based on a Chinese soil erodibiity database.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soil erodibility (K-value) is a key parameter in erosion prediction and is important for conservation planning in the face of a rising need for protecting the limited land resources. This study investigated the predictive capability of the K-value estimated by Universal Soil Loss Equation (USLE), Re...

  1. Temporal changes of eroded soils depending on their agricultural use in the southern Cis-Ural region

    NASA Astrophysics Data System (ADS)

    Gabbasova, I. M.; Suleimanov, R. R.; Khabirov, I. K.; Komissarov, M. A.; Fruehauf, M.; Liebelt, P.; Garipov, T. T.; Sidorova, L. V.; Khaziev, F. Kh.

    2016-10-01

    Temporal changes of eroded soils in the southern Cis-Ural region (Republic of Bashkortostan) depending on their agricultural use during the period from 1975 to 2011 were studied. In the northern foreststeppe zone, the development of erosion processes was retarded upon the use of soil-saving management practices and grain-fallow-grass crop rotations. In slightly eroded light gray forest soils (Eutric Retisols (Cutanic)), the thickness of humus-accumulative horizons and the content of humus increased; the conversion of cropland into permanent fallow was found to be the most efficient measure to control soil erosion. In podzolized chernozems (Luvic Greyzemic Chernic Phaeozems) and typical chernozems (Haplic Chernozems) of the Cis-Ural steppe, the content of humus in the plow layer under grain-row crop rotation and classical soil management decreased, especially in moderately eroded soils. The development of water and wind erosion on slopes depended on the slope shape: the texture of soils at different degrees of erosion on slopes with free runoff became coarser by one gradation after 35 years; in the presence of linear obstacles in the lower part of slopes, the content of fine fractions in moderately and strongly eroded soils increased.

  2. Joint effects of crude oil and heavy metals on the gill filament EROD activity of marbled rockfish Sebastiscus marmoratus.

    PubMed

    Zheng, Ronghui; Chen, Huanbin; Bo, Jun; Xie, Qing; Hong, Fukun; Zhang, Yusheng

    2016-10-01

    The aim of this study was to characterize dose- and time-dependent responses of gill 7-ethoxyresorufin O-deethylase (EROD) activity from Juvenile marbled rockfish (Sebastiscus marmoratus) exposed to the water-accommodated fraction (WAF) of crude oil and heavy metal Cd(Ⅱ) or Pb(Ⅱ) alone or in mixture. Compared to the control group, gill filament EROD activity in S. marmoratus was significantly induced after exposure to the WAF from 80 to 320μg/L for 5 days in dose response experiment and after exposure to 40μg/L WAF for 6-10 days in time course experiment, respectively. In the other hand, gill filament EROD activity were not significantly affected compared to the control group or related WAF groups no matter in the dose response experiment or in the time course experiment of Cd(Ⅱ), Pb(Ⅱ) or its mixture with WAF. The results suggest the use of gill filament EROD activity as a biomarker of exposure to waterborne AhR agonists in marine ecosystems while simultaneously being exposed to environmental concentrations of Cd(Ⅱ) or Pb(Ⅱ). PMID:27290642

  3. Medical Care: "Say Ahh!". Health and the Consumer.

    ERIC Educational Resources Information Center

    Florida State Dept. of Education, Tallahassee. Div. of Elementary and Secondary Education.

    Secondary level students learn about medical care in this learning activity package, which is one in a series. The developers believe that consumer education in the health field would ensure better patient care and help eliminate incompetent medical practices and practitioners. The learning package includes instructions for the teacher,…

  4. From "Ugh" to "Ahh": The Power of Sketchbooks

    ERIC Educational Resources Information Center

    Carlson, Pam

    2010-01-01

    "Art history? Ugh!" is often the response of high-school visual arts students when faced with an art-history assignment. With the exception of very few students who might have an affection for the historical aspects of art, getting art history into the hearts and minds of high-school students can be a challenge. In this article, the author shares…

  5. Physical Model and numerical modeling of earth-surface flows on erodible beds

    NASA Astrophysics Data System (ADS)

    Ouyang, Chaojun; He, Siming; Zhou, Gordan

    2015-04-01

    The bed sediment erosion and depositional processes along the channel play a significant role in geo-hazards like debris flows, landslides and dam failures. Large quantities of theoretical, experimental and field researches have shown that the final debris flow volume could possibly be several-fold beyond its initial volume as it incorporates material from the basal beds. A number of catastrophic events imply the damage is still generally underestimated, especially in the area influenced by strong earthquake such as Wenchuan 5.12 earthquake in 2008. An increasing number of researchers have been dedicated to using depth-integrated Na-vier-Stokes equations to determine the runout distance and final deposition volume of land-slides or debris flows over erodible beds. Nevertheless, it has been found out that the role of mass and momentum exchange at flow-bed boundaries in conservation equations was im-properly exhibited in some literatures, as reviewed by Iverson and Ouyang (2014). In addition, it is also illustrated that erosion or deposition rates at the interface between layers must satisfy three jump conditions which are similar to Rankine-Hugoniot conditions in gas dynamics. Here, several basal entrainment models satisfying the momentum jump conditions are proposed. Coupled mass and momentum equations integrated with sediment transport and morphological evolution are presented. A time and space second-order MacCormack-TVD finite difference method, which does not require the knowledge of the characteristic speeds of the system, is programmed to solve the coupled equations. A series of numerical simulations compared with theoretical solution and laboratory experiments were carried out to verify the accuracy and its robustness. Numerical comparisons with USGS flume experiment and Hongchun gully debris flow in Wenchuan earthquake-induced area are well carried out. It is exhibited the momentum exchange term between the flows and the basal materials has a sig

  6. Overwinter Changes in Wind Erodibility of Clay Loam Soils in Southern Alberta

    SciTech Connect

    Bullock, M S.; Larney, F. J.; Izaurralde, R Cesar C. ); Feng, Y

    2001-03-21

    Soil dry aggregate size distribution (DASD) and surface roughness are important factors affecting wind erodibility. This study monitored overwinter changes in DASD and surface roughness and identified relationships with climatic variables in the chinook-dominated region of southern Alberta. A different site was monitored in each of three winters (18 Sept. 1992 to 12 May 1993; 26 Oct. 1993 to 29 Apr. 1994; 30 Aug. 1994 to 24 May 1995) on Dark Brown Chernozemic clay loams (fine-loamy, mixed, Typic Haploborolls). The DASD was expressed as geometric mean diameter (GMD) and wind erodible fraction (EF). The GMD ranged from 1.88 to 0.08 mm in 1992-1993, from 9.05 to 1.17 mm in 1993-1994, and from 4.71 to 0.80 mm in 1994-1995. The EF range from 38.9 to 74.0% in 1992-1993, from 12.6 to 43.7% in 1993-1994, and 31.3 to 55.% in 1994-1995. Surface roughness was measured parallel (Cpar) to tillage direction on two of the sites. Using the chain method, Cper ranged from 15.1 to 3.7% in 1993-199 4 and from 14.4 to 3.3% in 1994-1995. Regression analysis with time revealed significant exponential decay for GMD (R2= 0.57 in 1992-1993, 0.97 in 1993-1994, and 0.78 in 1994-1995) and Cpar (R2= 0.98 in 1993-1994, 0.91 in 1994-1995) and a positive linear fit for EF (R2= 0.57 in 1992-1993, 0.91 in 1993-1994, and 0.62 in 1994-1995). Three overwinter periods, differentiated by the timing and form of precipitation and designated as''fall rain/snow'',''winter snow'', and''spring snow/rain'', were used to assess the changes in EF using cumulative freeze-thaw cycles, precipitation, and snow cover

  7. Erosion characteristics of an erodible tablet incorporated in a time-delayed capsule device.

    PubMed

    McConville, Jason T; Ross, Alistair C; Florence, Alastair J; Stevens, Howard N E

    2005-01-01

    A time-delayed oral drug delivery device was investigated in which an erodible tablet (ET), sealing the mouth of an insoluble capsule, controlled the lag-time prior to drug release. The time-delayed capsule (TDC) lag-time may be altered by manipulation of the excipients used in the preparation of the ET. Erosion rates and drug release profiles from TDCs were investigated with four different excipient admixtures with lactose: calcium sulphate dihydrate (CSD), dicalcium phosphate (DCP), hydroxypropylmethyl cellulose (HPMC; Methocel K100LV grade) and silicified microcrystalline cellulose (SMCC; Prosolv 90 grade). Additionally, the compressibility of different insoluble coated capsules was tested at different moisture levels to determine their overall integrity and suitability for oral delivery. Erosion rates of CSD, DCP, and SMCC displayed a nonlinear relationship to their concentration, while HPMC indicated rapid first-order erosion followed by zero-order erosion, the onset of which was dependent on the HPMC concentration. Capsule integrity was confirmed to be most suitable for oral delivery when the insoluble ethyl cellulose coat was applied to a hard gelatin capsule using an organic spray coating process. T50% drug release times varied between 245 (+/-33.4) and 393 (+/-40.8) minutes for 8% and 20% DCP, respectively, T50% release times of 91 (+/-22.1) and 167 (+/-34.6) were observed for 8% and 20% CSD; both formulations showed incidence of premature drug release. The SMCC formulations showed high variability due to lamination effects. The HPMC formulations had T50% release times of 69 (+/-13.9), 213 (+/-25.4), and 325 (+/-30.3) minutes for 15%, 24%, and 30% HPMC concentrations respectively, with no premature drug release. In conclusion, HPMC showed the highest reproducibility for a range of time-delayed drug release from the assembled capsule formulation. The method of capsule coating was confirmed to be important by investigation of the overall capsule integrity at

  8. Effect of Various Organic Matter stimulates Bacteria and Arbuscular Mycorrhizal Fungi Plantations on Eroded Slopes in Nepal

    NASA Astrophysics Data System (ADS)

    Shrestha Vaidya, G.; Shrestha, K.; Wallander, H.

    2009-04-01

    Erosion resulting from landslides is a serious problem in mountainous countries such as Nepal. To restore such sites it is essential to establish plant cover that protects the soil and reduces erosion. Trees and shrubs on the lower hillsides in Nepal form symbiosis with arbuscular mycorrhizal (AM) fungi and these fungi are important for the uptake of mineral nutrients from the soil. In addition, the mycelia formed by these fungi have an important function in stabilizing the soil. The success of plantations of these eroded slopes is therefore highly dependent on the extent of mycorrhizal colonization of the plants. Mycorrhizal fungi growing in symbiosis with plants are essential in this respect because they improve both plant and nutrient uptake and soil structure. We investigated the influence of organic matter and P amendment on recently produced biomass of bacteria and arbuscular mycorrhizal (AM) fungi in eroded slopes in Nepal. Eroded soil mixed with different types of organic matter was placed in mesh bags which were buried around the trees of Bauhinia purpurea and Leucaena diversifolia .This experiment were done in two seasons ( (the wet and the dry season). Signature fatty acids were used to determine bacterial and AM fungal biomass after the six month intervals. The amount and composition of AM fungal spores were analyzed in the mesh bags from the wet and dry seasons. More microbial biomass was produced during wet season than during dry season. Further more, organic matter addition enhanced the production of AM fungal and bacterial biomass during both seasons. The positive influence of organic matter addition on AM fungi could be an important contribution to plant survival, growth and nutrient composition in the soil in plantations on eroded slopes. Different AM spore communities and bacterial profiles were obtained with different organic amendments and this suggests a possible way of selecting for specific microbial communities in the management of eroded

  9. Geospatial approach in mapping soil erodibility using CartoDEM - A case study in hilly watershed of Lower Himalayan Range

    NASA Astrophysics Data System (ADS)

    Kumar, Suresh; Gupta, Surya

    2016-09-01

    Soil erodibility is one of the most important factors used in spatial soil erosion risk assessment. Soil information derived from soil map is used to generate soil erodibility factor map. Soil maps are not available at appropriate scale. In general, soil maps at small scale are used in deriving soil erodibility map that largely generalized spatial variability and it largely ignores the spatial variability since soil map units are discrete polygons. The present study was attempted to generate soil erodibilty map using terrain indices derived from DTM and surface soil sample data. Soil variability in the hilly landscape is largely controlled by topography represented by DTM. The CartoDEM (30 m) was used to derive terrain indices such as terrain wetness index (TWI), stream power index (SPI), sediment transport index (STI) and slope parameters. A total of 95 surface soil samples were collected to compute soil erodibility factor (K) values. The K values ranged from 0.23 to 0.81 t ha-1R-1 in the watershed. Correlation analysis among K-factor and terrain parameters showed highest correlation of soil erodibilty with TWI (r 2= 0.561) followed by slope (r 2= 0.33). A multiple linear regression model was developed to derive soil erodibilty using terrain parameters. A set of 20 soil sample points were used to assess the accuracy of the model. The coefficient of determination (r 2) and RMSE were computed to be 0.76 and 0.07 t ha-1R-1 respectively. The proposed methodology is quite useful in generating soil erodibilty factor map using digital elevation model (DEM) for any hilly terrain areas. The equation/model need to be established for the particular hilly terrain under the study. The developed model was used to generate spatial soil erodibility factor (K) map of the watershed in the lower Himalayan range.

  10. Effect of copper chloride in vitro and in vivo on the hepatic EROD activity in the fish Dicentrarchus labrax

    SciTech Connect

    Stien, X.; Risso, C.; Gnassia-Barelli, M.; Romeo, M.; LaFaurie, M.

    1997-02-01

    The effect of copper chloride was studied on the hepatic microsomal 7-ethoxyresorufin-O-deethylase (EROD) activity of the fish Dicentrarchus labrax intraperitoneally injected with benzo[a]pyrene (BaP). In vitro experiments showed that copper significantly decreased EROD activity, and IC50 was estimated at 50 {micro}g Cu/L. The apparent Michaelis constant (K{sub m}) of cytochrome P4501A was constant, whereas maximum velocity (V{sub max}) decreased as a function of copper added to the incubation medium. (K{sub m}) of nicotinamide adenine dinucleotide phosphate [NADPH]-cytochrome P450 reductase increased as a function of copper concentration, whereas V{sub max} remained constant. Absorption spectra showed that the amount of cytochrome P420s increased as a function of copper concentrations added to the medium at the expense of cytochrome P450s. The injection of copper and BaP to fish decreased EROD activity compared with the injection of BaP alone. An increase of immunoquantified CYP1A content measured by Western blotting was noted in microsomes of fish injected with BaP compared with controls. In the case of fish treated with copper and BaP, the band was less intense and accompanied by another band of lower molecular weight. The destruction of the native P450s spectrophotometrically measured in the presence of copper implied that the catalytic activity would be diminished. This was confirmed by decreased EROD activity after either in vitro additions or in vivo treatment with copper. Moreover, immunodetection experiments suggested that the decrease of the catalytic activity resulted more from cytochrome P450s loss than from direct inhibition of EROD activity by copper.

  11. Sex-ratio control erodes sexual selection, revealing evolutionary feedback from adaptive plasticity.

    PubMed

    Fawcett, Tim W; Kuijper, Bram; Weissing, Franz J; Pen, Ido

    2011-09-20

    Female choice is a powerful selective force, driving the elaboration of conspicuous male ornaments. This process of sexual selection has profound implications for many life-history decisions, including sex allocation. For example, females with attractive partners should produce more sons, because these sons will inherit their father's attractiveness and enjoy high mating success, thereby yielding greater fitness returns than daughters. However, previous research has overlooked the fact that there is a reciprocal feedback from life-history strategies to sexual selection. Here, using a simple mathematical model, we show that if mothers adaptively control offspring sex in relation to their partner's attractiveness, sexual selection is weakened and male ornamentation declines. This weakening occurs because the ability to determine offspring sex reduces the fitness difference between females with attractive and unattractive partners. We use individual-based, evolutionary simulations to show that this result holds under more biologically realistic conditions. Sexual selection and sex allocation thus interact in a dynamic fashion: The evolution of conspicuous male ornaments favors sex-ratio adjustment, but this conditional strategy then undermines the very same process that generated it, eroding sexual selection. We predict that, all else being equal, the most elaborate sexual displays should be seen in species with little or no control over offspring sex. The feedback process we have described points to a more general evolutionary principle, in which a conditional strategy weakens directional selection on another trait by reducing fitness differences.

  12. Micro-structured, spontaneously eroding hydrogels accelerate endothelialization through presentation of conjugated growth factors.

    PubMed

    Jensen, Bettina E B; Edlund, Katrine; Zelikin, Alexander N

    2015-05-01

    Growth factors represent highly potent and highly efficacious means of communication to cells. At the same time, these proteins are fragile and relatively small sized--rendering their immobilization and controlled release from biomaterials challenging. In this work, we establish a method to incorporate growth factors into the physical hydrogels based on poly(vinyl alcohol), PVA. The latter have a long and successful history of biomedical applications and approval for diverse use in human patients, but are also characterized with scant opportunities for bioconjugation and functionalization. Herein, we develop the conjugation of growth factors to the micro-structured, spontaneously eroding physical hydrogels based on PVA. Protein conjugation was elaborated using model substrates, albumin and lysozyme, which aided to reveal specificity of chemical reactions and benign, non-harmful nature of the established protocols. Surface-adhered format of hydrogel analyses allowed to quantify bioconjugation reactions and enzymatic activity of the immobilized proteins and to visualize the hydrogels with immobilized cargo. In cell culture, immobilized growth factors were effective in communicating to adhering cells and specifically enhanced proliferation rates of the cells containing the corresponding receptors. At the same time, proliferation of the cells devoid of these receptors was un-altered. PMID:25725560

  13. Tritium recycling and inventory in eroded debris of plasma-facing materials

    SciTech Connect

    Hassanein, A.

    1999-10-18

    Damage to plasma-facing components (PFCs) and structural materials due to loss of plasma confinement in magnetic fusion reactors remains one of the most serious concerns for safe, successful, and reliable tokamak operation. High erosion losses due to surface vaporization, spallation, and melt-layer splashing are expected during such an event. The eroded debris and dust of the PFCs, including trapped tritium, will be contained on the walls or within the reactor chamber therefore, they can significantly influence plasma behavior and tritium inventory during subsequent operations. Tritium containment and behavior in PFCS and in the dust and debris is an important factor in evaluating and choosing the ideal plasma-facing materials (PFMs). Tritium buildup and release in the debris of candidate materials is influenced by the effect of material porosity on diffusion and retention processes. These processes have strong nonlinear behavior due to temperature, volubility, and existing trap sites. A realistic model must therefore account for the nonlinear and multidimensional effects of tritium diffusion in the porous-redeposited and neutron-irradiated materials. A tritium-transport computer model, TRAPS (Tritium Accumulation in Porous Structure), was developed and used to evaluate and predict the kinetics of tritium transport in porous media. This model is coupled with the TRICS (Tritium In Compound Systems) code that was developed to study the effect of surface erosion during normal and abnormal operations on tritium behavior in PFCS.

  14. Cosmogenic {sup 36}Cl accumulation in unstable landforms 2. Simulations and measurements on eroding moraines

    SciTech Connect

    Zreda, M.G.; Phillips, F.M.; Elmore, D.

    1994-11-01

    Cosmogenic {sup 36}Cl ages of boulders from late Pleistocene moraines in Bishop Creek, Sierra Nevada, California, provided valuable details about {sup 36}Cl surface exposure dating and the nature of post depositional processes that modify glacial landforms. The natural variability of the apparent {sup 36}Cl ages among morainal boulders is due to soil erosion and gradual exposure of boulders at the surface. Two mechanisms are responsible for the resulting distributions of the apparent {sup 36}Cl ages. Variability of the initial burial depth among boulders and variability in the chemical composition of boulders from the same depth both result in different {sup 36}Cl ages due to the dependence of the depth production profile on the boulder chemistry. The authors measured cosmogenic {sup 36}Cl in boulders from a late Pleistocene moraine. The distribution of the calculated apparent ages allowed them to calculate the true age of 85 kyr and the erosion rate of 570 g cm{sup -2}. These results are in excellent agreement with independently estimated values of 87 kyr and 600 g cm{sup -2} for the age and erosion depth, respectively. These results indicate that the model satisfactorily simulates effects of erosion processes and can thus aid in surface exposure dating of eroding landforms.

  15. Irrigation and Maize Cultivation Erode Plant Diversity Within Crops in Mediterranean Dry Cereal Agro-Ecosystems

    NASA Astrophysics Data System (ADS)

    Fagúndez, Jaime; Olea, Pedro P.; Tejedo, Pablo; Mateo-Tomás, Patricia; Gómez, David

    2016-07-01

    The intensification of agriculture has increased production at the cost of environment and biodiversity worldwide. To increase crop yield in dry cereal systems, vast farmland areas of high conservation value are being converted into irrigation, especially in Mediterranean countries. We analyze the effect of irrigation-driven changes on the farm biota by comparing species diversity, community composition, and species traits of arable plants within crop fields from two contrasting farming systems (dry and irrigated) in Spain. We sampled plant species within 80 fields of dry wheat, irrigated wheat, and maize (only cultivated under irrigation). Wheat crops held higher landscape and per field species richness, and beta diversity than maize. Within the same type of crop, irrigated wheat hosted lower plant diversity than dry wheat at both field and landscape scales. Floristic composition differed between crop types, with higher frequencies of perennials, cosmopolitan, exotic, wind-pollinated and C4 species in maize. Our results suggest that irrigation projects, that transform large areas of dry cereal agro-ecosystems into irrigated crop systems dominated by maize, erode plant diversity. An adequate planning on the type and proportion of crops used in the irrigated agro-ecosystems is needed in order to balance agriculture production and biodiversity conservation.

  16. Numerical investigation of temperature distribution in an eroded bend pipe and prediction of erosion reduced thickness.

    PubMed

    Zhu, Hongjun; Feng, Guang; Wang, Qijun

    2014-01-01

    Accurate prediction of erosion thickness is essential for pipe engineering. The objective of the present paper is to study the temperature distribution in an eroded bend pipe and find a new method to predict the erosion reduced thickness. Computational fluid dynamic (CFD) simulations with FLUENT software are carried out to investigate the temperature field. And effects of oil inlet rate, oil inlet temperature, and erosion reduced thickness are examined. The presence of erosion pit brings about the obvious fluctuation of temperature drop along the extrados of bend. And the minimum temperature drop presents at the most severe erosion point. Small inlet temperature or large inlet velocity can lead to small temperature drop, while shallow erosion pit causes great temperature drop. The dimensionless minimum temperature drop is analyzed and the fitting formula is obtained. Using the formula we can calculate the erosion reduced thickness, which is only needed to monitor the outer surface temperature of bend pipe. This new method can provide useful guidance for pipeline monitoring and replacement.

  17. Self-similar evolution of 2D aquatic dunes over an erodible bed

    NASA Astrophysics Data System (ADS)

    Doppler, Delphine; Lagrée, Pierre Yves; Gondret, Philippe; Rabaud, Marc

    2015-11-01

    Scale invariance of shape is a common feature of erosion patterns, such as barchan dunes, sand ripples under shoaling waves or scour holes. Due to their universal and fascinating crescentic shape, barchans dunes have received much attention and scaling laws have been deduced from field observations, satellite images and laboratory experiments. On the other hand, the dynamical long term evolution of ripples and dunes formed over an erodible bed has been far less studied while the temporal behavior of erosion patterns contains substantial information on the physical processes involved. Here, we present experimental results obtained in a linear, quasi-2D closed water channel. When a granular bed is submitted to a uniform shear flow, periodic sand ripples appear all along the channel. We found that the first ripple near the channel inlet exhibit unreported long-term scale-invariant growth. The self-similar dune shape and power-law growth exponent are extracted by image processing for several flow velocity. A simple linear model is built using mass conservation and a granular flux law, so that the bed form is described by a self-similar order 2 linear system. Experimental data fit nicely with the model results.

  18. Runoff and erosion from a rapidly eroding pinyon-juniper hillslope

    SciTech Connect

    Wilcox, B.P.; Davenport, D. W.; Pitlick, J.; Allen, C.D.

    1996-02-01

    The dramatic acceleration of erosion associated with the expansion of pinyon-juniper woodlands over the past 100 years has been a widely recognized but poorly understood phenomenon. A more complete understanding will come only through long-term observations of erosion and related factors. To this end, we are conducting a study of a small (1-ha) catchment in a rapidly eroding pinyon-juniper woodland. Since July 1993, we have been collecting data on runoff, erosion, and weather conditions in the catchment, as well as on the topography, soils, and vegetation. Our preliminary results suggest that (1) the catchment is currently in a cycle of accelerated erosion that began concomitant with a shift from ponderosa pine forest to pinyon-juniper woodland that was initiated by a prolonged drought; (2) the intercanopy soils cannot be sustained at the current erosion rates and will be mostly stripped away in about a century; (3) large summer thunderstorms are the most important agents of erosion (4) erosion increases dramatically as the scale increases; (5) runoff makes up <10% of the water budget.

  19. Polar bear hepatic cytochrome P450: Immunochemical quantitation, EROD/PROD activity and organochlorines

    SciTech Connect

    Letcher, R.J.; Norstrom, R.J. |

    1994-12-31

    Polar bears (Ursus maritimus) are an ubiquitous mammal atop the arctic marine food chain and bioaccumulate lipophilic environmental contaminants. Antibodies prepared against purified rat liver cytochrome P450-1 Al, -1 A2, -2Bl and -3Al enzymes have been found to cross-react with structurally-related orthologues present in the hepatic microsomes of wild polar bears, immunochemically determined levels of P450-1 A and -2B proteins in polar bear liver relative to liver of untreated rats suggested enzyme induction, probably as a result of exposure to xenobiotic contaminants. Optical density quantitation of the most immunochemically responsive isozymes P450-I Al, -IA2 and -2Bi to polygonal rabbit anti-rat P450-IA/IA2 sera and -2BI antibodies in hepatic microsomes of 13 adult male polar bars from the Resolute Bay area of the Canadian Arctic is presented. Correlations with EROD and PROD catalytic activities and levels of organochlorines, such as polychlorinated biphenyls (PCBs), 1,1-dichloro-2,2-bis(4-chlorophenyl)ethene (p,p-DDE) and their methyl sulfone (MeSO2-) metabolites are made to determine if compound-specific enzyme induction linkages exist. Inter-species immunochemical quantitation of isozymic P450 cytochromes can serve as an indicator of exposure to biologically active contaminant.

  20. Irrigation and Maize Cultivation Erode Plant Diversity Within Crops in Mediterranean Dry Cereal Agro-Ecosystems.

    PubMed

    Fagúndez, Jaime; Olea, Pedro P; Tejedo, Pablo; Mateo-Tomás, Patricia; Gómez, David

    2016-07-01

    The intensification of agriculture has increased production at the cost of environment and biodiversity worldwide. To increase crop yield in dry cereal systems, vast farmland areas of high conservation value are being converted into irrigation, especially in Mediterranean countries. We analyze the effect of irrigation-driven changes on the farm biota by comparing species diversity, community composition, and species traits of arable plants within crop fields from two contrasting farming systems (dry and irrigated) in Spain. We sampled plant species within 80 fields of dry wheat, irrigated wheat, and maize (only cultivated under irrigation). Wheat crops held higher landscape and per field species richness, and beta diversity than maize. Within the same type of crop, irrigated wheat hosted lower plant diversity than dry wheat at both field and landscape scales. Floristic composition differed between crop types, with higher frequencies of perennials, cosmopolitan, exotic, wind-pollinated and C4 species in maize. Our results suggest that irrigation projects, that transform large areas of dry cereal agro-ecosystems into irrigated crop systems dominated by maize, erode plant diversity. An adequate planning on the type and proportion of crops used in the irrigated agro-ecosystems is needed in order to balance agriculture production and biodiversity conservation.

  1. Gains in medication affordability following Medicare Part D are eroding among elderly with multiple chronic conditions

    PubMed Central

    Naci, Huseyin; Soumerai, Stephen B; Ross-Degnan, Dennis; Zhang, Fang; Briesacher, Becky A; Gurwitz, Jerry H; Madden, Jeanne M

    2014-01-01

    Elderly Americans, especially those with multiple chronic conditions, face difficulties paying for prescriptions, resulting in worse adherence and discontinuation of therapy (“cost-related medication nonadherence” or CRN). We investigated whether the gains in medication affordability attributable to Medicare Part D implementation in January 2006 persisted during the six years that followed. Overall, we found continued incremental improvements in medication affordability in the early years of Part D (2007–2009), which then eroded during more recent years (2009–2011). Among elderly beneficiaries with four or more chronic conditions, we observed an increase in the prevalence of CRN from 14.4% in 2009 to 17.0% in 2011, reversing previous downward trends. Similarly, the prevalence of forgoing basic needs in order to purchase medicines among the sickest elderly decreased from 8.7% in 2007 to 6.8% in 2009, then rose to 10.2% in 2011. Our findings highlight the need for targeted policy efforts to alleviate the persistent burden of drug treatment costs in this vulnerable population. PMID:25092846

  2. PARP1 is a TRF2-associated poly(ADP-ribose) polymerase and protects eroded telomeres

    SciTech Connect

    Gomez, Marla V; Wu, Jun; Wang, Yisong; Liu, Yie

    2006-01-01

    Poly(ADP-ribose)polymerase 1 (PARP1) is well characterized for its role in base excision repair (BER), where it is activated by and binds to DNA breaks and catalyzes the poly(ADP-ribosyl)ation of several substrates involved in DNA damage repair. Here we demonstrate that PARP1 associates with telomere repeat binding factor 2 (TRF2) and is capable of poly(ADP-ribosyl)ation of TRF2, which affects binding of TRF2 to telomeric DNA. Immunostaining of interphase cells or metaphase spreads shows that PARP1 is detected sporadically at normal telomeres, but it appears preferentially at eroded telomeres caused by telomerase deficiency or damaged telomeres induced by DNA-damaging reagents. Although PARP1 is dispensable in the capping of normal telomeres, Parp1 deficiency leads to an increase in chromosome end-to-end fusions or chromosome ends without detectable telomeric DNA in primary murine cells after induction of DNA damage. Our results suggest that upon DNA damage, PARP1 is recruited to damaged telomeres, where it can help protect telomeres against chromosome end-to-end fusions and genomic instability.

  3. Mousso structure: A deeply eroded, medium-sized, complex impact crater in northern Chad?

    NASA Astrophysics Data System (ADS)

    Buchner, Elmar; Schmieder, Martin

    2007-10-01

    The Mousso structure, a complex, ˜3.8 km circular structure centred on 17°58' N/19°53' E and located near the Mousso oasis, Borkou-Ennedi-Tibesti, northern Chad, displays structural features typical for complex impact structures: a circular rim with concentric faults, an annular basin, and a central peak. Remote sensing investigations based on Landsat-7 Enhanced Thematic Mapper Plus (ETM+) and Shuttle Radar Topographic Mission (SRTM) data reveal a specific morphological-structural resemblance of the complex central peak of the Mousso structure to the central uplift of the Spider impact structure, Western Australia, and, to some degree, to the central uplifts of the Upheaval Dome, Sierra Madera, and Gosses Bluff impact structures. This is consistent with the layered sedimentary rocks associated with all of these structures. No endogenic geological processes such as magmatism, diapirism, karst dissolution, and glacial or fluvial erosion can conclusively explain the formation of the Mousso structure within a large area of flat-lying early Paleozoic sandstones. Thus, this paper proposes that the Mousso structure might represent a deeply eroded, medium-sized, complex impact structure. As field investigations are currently impossible due to the civil war in Chad, the search for shock-metamorphic effects in rocks of the Mousso structure remains outstanding.

  4. PARP1 Is a TRF2-associated Poly(ADP-Ribose)Polymerase and Protects Eroded Telomeres

    SciTech Connect

    Liu, Yie; Wu, Jun; Schreiber, Valerie; Dunlap, John; Dantzer, Francoise; Wang, Yisong

    2006-01-01

    Poly(ADP-ribose)polymerase 1 (PARP1) is well characterized for its role in base excision repair (BER), where it is activated by and binds to DNA breaks and catalyzes the poly(ADP-ribosyl)ation of several substrates involved in DNA damage repair. Here we demonstrate that PARP1 associates with telomere repeat binding factor 2 (TRF2) and is capable of poly(ADP-ribosyl)ation of TRF2, which affects binding of TRF2 to telomeric DNA. Immunostaining of interphase cells or metaphase spreads shows that PARP1 is detected sporadically at normal telomeres, but it appears preferentially at eroded telomeres caused by telomerase deficiency or damaged telomeres induced by DNA-damaging reagents. Although PARP1 is dispensable in the capping of normal telomeres, Parp1 deficiency leads to an increase in chromosome end-to-end fusions or chromosome ends without detectable telomeric DNA in primary murine cells after induction of DNA damage. Our results suggest that upon DNA damage, PARP1 is recruited to damaged telomeres, where it can help protect telomeres against chromosome end-to-end fusions and genomic instability.

  5. Measurements of high-frequency acoustic scattering from glacially eroded rock outcrops.

    PubMed

    Olson, Derek R; Lyons, Anthony P; Sæbø, Torstein O

    2016-04-01

    Measurements of acoustic backscattering from glacially eroded rock outcrops were made off the coast of Sandefjord, Norway using a high-frequency synthetic aperture sonar (SAS) system. A method by which scattering strength can be estimated from data collected by a SAS system is detailed, as well as a method to estimate an effective calibration parameter for the system. Scattering strength measurements from very smooth areas of the rock outcrops agree with predictions from both the small-slope approximation and perturbation theory, and range between -33 and -26 dB at 20° grazing angle. Scattering strength measurements from very rough areas of the rock outcrops agree with the sine-squared shape of the empirical Lambertian model and fall between -30 and -20 dB at 20° grazing angle. Both perturbation theory and the small-slope approximation are expected to be inaccurate for the very rough area, and overestimate scattering strength by 8 dB or more for all measurements of very rough surfaces. Supporting characterization of the environment was performed in the form of geoacoustic and roughness parameter estimates. PMID:27106331

  6. Interaction between an axial-flow model hydrokinetic turbine and an erodible channel

    NASA Astrophysics Data System (ADS)

    Hill, Craig; Musa, Mirko; Chamorro, Leonardo P.; Guala, Michele

    2013-11-01

    Laboratory experiments were carried out to examine the effect of relatively large-scale bedforms on the performance of a model axial-flow hydrokinetic turbine. The turbine rotor, dT = 0 . 15 m, was attached to a miniature DC motor, and allowed for voltage data acquisition at 200 Hz along with 3D hub-height inflow velocity, Uhub, approximately 7dT upstream of the turbine. Spatio-temporal bed elevations were acquired along three longitudinal sections and at least one transverse transect within the flume providing the temporally-averaged scour and deposition patterns characterizing the turbine near-field region. Turbine-turbine interaction was investigated under aligned configurations in the streamwise direction with variable spacing both in clear water scour and live bed transport conditions. Effects from both migrating bedforms and the upstream turbine were observed in the long-term and short-term voltage fluctuations of the downstream turbine. Combined measurements of inflow velocity, bed topography and turbine voltage were used to obtain joint statistics and correlations, which provided an indication of the variability in environmental exposure and performance that hydrokinetic turbines will encounter in natural erodible rivers.

  7. Local and non-local effects of spanwise finite perturbations in erodible river bathymetries

    NASA Astrophysics Data System (ADS)

    Musa, Mirko; Hill, Craig; Guala, Michele

    2015-11-01

    Laboratory experiments were performed to study the effect of axial-flow hydrokinetic turbine models on an erodible river bed under live-bed conditions. Results indicate that the presence of an operating turbine rotor creates a blockage in the mean flow which produces a remarkable geomorphic signature in the migrating bedforms. These impacts affect a local area downstream of the turbines when placed symmetrically with respect to the cross section of the channel. On the other hand, more interesting results are observed with an asymmetric installation of the turbines. This configuration demonstrates a stronger effect on the mean flow, resulting in a larger plan-wise distortion of the mean topography and differential migration patterns of bedforms. Different turbine installation arrangements and hub heights above the mean bed were investigated, focusing mainly on the perturbation of sediment transport characteristics influenced by the turbine wake. Additional results with spanwise modulated submerged walls explore the possibility to control river topography harvesting this type of geomorphic destabilization.

  8. Micro-structured, spontaneously eroding hydrogels accelerate endothelialization through presentation of conjugated growth factors.

    PubMed

    Jensen, Bettina E B; Edlund, Katrine; Zelikin, Alexander N

    2015-05-01

    Growth factors represent highly potent and highly efficacious means of communication to cells. At the same time, these proteins are fragile and relatively small sized--rendering their immobilization and controlled release from biomaterials challenging. In this work, we establish a method to incorporate growth factors into the physical hydrogels based on poly(vinyl alcohol), PVA. The latter have a long and successful history of biomedical applications and approval for diverse use in human patients, but are also characterized with scant opportunities for bioconjugation and functionalization. Herein, we develop the conjugation of growth factors to the micro-structured, spontaneously eroding physical hydrogels based on PVA. Protein conjugation was elaborated using model substrates, albumin and lysozyme, which aided to reveal specificity of chemical reactions and benign, non-harmful nature of the established protocols. Surface-adhered format of hydrogel analyses allowed to quantify bioconjugation reactions and enzymatic activity of the immobilized proteins and to visualize the hydrogels with immobilized cargo. In cell culture, immobilized growth factors were effective in communicating to adhering cells and specifically enhanced proliferation rates of the cells containing the corresponding receptors. At the same time, proliferation of the cells devoid of these receptors was un-altered.

  9. [Temporal variations of clay content in eroded sediment under different rainfall condition].

    PubMed

    Wu, Feng-Zhi; Shi, Zhi-Hua; Fang, Nu-Fang; Yue, Ben-Jiang

    2012-07-01

    Erosion and sediment characteristics were measured using simulated rainfall on two cultivated soils from the Loess Plateau, China. The size distribution of eroded sediment (non-dispersed) was compared with equivalent measurements of the same samples after chemical and mechanical dispersion(dispersed) to investigate the aggregation ratio (AR) and enrichment ratio (ER). Results show that clay content is increasing with the length and rainfall intensity. The loessial soil increased by 8.77% and 2.43%, but the Lou soil increased by only 2.76% and 0.4%. With the increase of slope, the clay content of the two loess reduced by 4.91% and 3.93%, respectively. AR values were less than 1 and ER values were greater than 1. These indicated that relatively slight clay dispersion occurred and that most of the clay in the sediments was in the form of aggregates. The results will improve understanding of erosion and sedimentation processes, which in turn will improve erosion modeling. Knowledge of temporal variations of clay in sediment can also provide the basis for understanding and modeling the transfer of nutrients on hillslope.

  10. Vortex shedding and morphodynamic response of bed surfaces containing non-erodible roughness elements

    NASA Astrophysics Data System (ADS)

    McKenna Neuman, Cheryl; Sanderson, Robert Steven; Sutton, Stephen

    2013-09-01

    A series of wind tunnel experiments was carried out to investigate particle entrainment from surfaces in which one or more roughness elements were embedded. Thin sand strips were employed to eliminate impact and ejection, and thus isolate entrainment by fluid drag. The pattern of erosion is consistent with the presence of coherent vortices, inclusive of trailing vortices in the wake flow. The shape and orientation of the roughness element strongly influence this pattern. When an upwind supply of saltators is introduced, the majority of particles within the bed are entrained through impact, with the exception of a sand tail to the lee of the roughness element. That is, the effect of coherent structures within the airflow, as related to spatial variation in the fluid drag exerted on the bed surface, is completely overprinted by the saltation cloud and the blocking of particle trajectories by the upwind face of the roughness element. In a repeated set of experiments, the bed was allowed to fully adjust its morphology to the transport system. In this case, particle entrainment did not selectively occur within the zone of wake flow, and by inference the fluid stress across the test surface appeared to be uniform. These experiments support the hypothesis that vortex annihilation occurs on morphodynamically adjusted surfaces. In summary, the system response to the emergence of non-erodible roughness elements on surfaces affected by wind erosion involves a suite of geophysical processes, each of which attains varied levels of dominance within a given morphodynamic domain.

  11. Evaluation of the WEPP hillslope model on stable and eroding semiarid woodlands

    SciTech Connect

    Wilcox, B.P.; Simanton, J.R.

    1995-12-01

    In this paper, we evaluate runoff and erosion prediction by the WEPP hillslope model for two pinyon-juniper sites in New Mexico: one has a low erosion rate (stable site) and the other (unstable site) is eroding at very rapid rates (as a result of landuse and climatic perturbations over the last century). Runoff and erosion measurements were made at plot and hillslope scales at both sites. WEPP was evaluated using both rainfall simulation and natural rainfall data. Rainfall simulation was performed on both vegetated and bare plots. Parameter values used were developed from rainfall simulation experiments and site characteristics. In general, runoff and erosion were underpredicted at both sites but to a much larger degree at the unstable site. On the unstable site predictions were much improved when we used hydraulic conductivity (Ke) derived from the bare plot rainfall simulation. Also of importance, at the unstable site we observed a large increase in erosion as scale increased from the plot to the hillslope as a result of a well developed channel network. These results are preliminary, in that only a few storms were evaluated, however, they do suggest some important strategies for predicting the impact of reduced vegetation cover to erosion in semiarid landscapes.

  12. Workplace bullying erodes job and personal resources: between- and within-person perspectives.

    PubMed

    Tuckey, Michelle R; Neall, Annabelle M

    2014-10-01

    Workplace bullying is a serious psychosocial occupational hazard. Despite a wealth of empirical study, research has rarely examined the mechanisms through which bullying has its negative effects. Accordingly, using both between- and within-person approaches, we investigated the erosion of job (Study 1) and personal (Study 2) resources following workplace bullying, mediated by the depletion of emotional energy. In Study 1, self-report survey data were collected from 221 retail workers at 2 time-points spaced 6 months apart. Structural equation modeling revealed that over time bullying depletes coworker support, partially mediated by emotional exhaustion. In Study 2, a 6-week diary was completed by a separate sample of 45 workers employed in various occupations. Within-person weekly variability in bullying exposure was 34%. Hierarchical linear modeling showed that weekly emotional exhaustion partially mediated the negative effects of weekly workplace bullying on both optimism and self-efficacy. The consistent pattern across both studies supports the idea of a resource loss process whereby exposure to bullying at work erodes job and personal resources by depleting energy. Future research should clarify the role of exhaustion in utilizing resources to respond to bullying, focus on predictors of within-person variability in bullying exposure, and more explicitly model the resource loss spiral following workplace bullying. PMID:25151461

  13. Modification of Roberts' Theory for Rocket Exhaust Plumes Eroding Lunar Soil

    NASA Technical Reports Server (NTRS)

    Metzger, Philip T.; Lane, John E.; Immer, Christopher D.

    2008-01-01

    In preparation for the Apollo program, Leonard Roberts developed a remarkable analytical theory that predicts the blowing of lunar soil and dust beneath a rocket exhaust plume. Roberts' assumed that the erosion rate is determined by the "excess shear stress" in the gas (the amount of shear stress greater than what causes grains to roll). The acceleration of particles to their final velocity in the gas consumed a portion of the shear stress. The erosion rate continues to increase until the excess shear stress is exactly consumed, thus determining the erosion rate. He calculated the largest and smallest particles that could be eroded based on forces at the particle scale, but the erosion rate equation assumes that only one particle size exists in the soil. He assumed that particle ejection angles are determined entirely by the shape of the terrain, which acts like a ballistic ramp, the particle aerodynamics being negligible. The predicted erosion rate and particle upper size limit appeared to be within an order of magnitude of small-scale terrestrial experiments, but could not be tested more quantitatively at the time. The lower particle size limit and ejection angle predictions were not tested.

  14. Measurements of high-frequency acoustic scattering from glacially eroded rock outcrops.

    PubMed

    Olson, Derek R; Lyons, Anthony P; Sæbø, Torstein O

    2016-04-01

    Measurements of acoustic backscattering from glacially eroded rock outcrops were made off the coast of Sandefjord, Norway using a high-frequency synthetic aperture sonar (SAS) system. A method by which scattering strength can be estimated from data collected by a SAS system is detailed, as well as a method to estimate an effective calibration parameter for the system. Scattering strength measurements from very smooth areas of the rock outcrops agree with predictions from both the small-slope approximation and perturbation theory, and range between -33 and -26 dB at 20° grazing angle. Scattering strength measurements from very rough areas of the rock outcrops agree with the sine-squared shape of the empirical Lambertian model and fall between -30 and -20 dB at 20° grazing angle. Both perturbation theory and the small-slope approximation are expected to be inaccurate for the very rough area, and overestimate scattering strength by 8 dB or more for all measurements of very rough surfaces. Supporting characterization of the environment was performed in the form of geoacoustic and roughness parameter estimates.

  15. Numerical Investigation of Temperature Distribution in an Eroded Bend Pipe and Prediction of Erosion Reduced Thickness

    PubMed Central

    Zhu, Hongjun; Feng, Guang; Wang, Qijun

    2014-01-01

    Accurate prediction of erosion thickness is essential for pipe engineering. The objective of the present paper is to study the temperature distribution in an eroded bend pipe and find a new method to predict the erosion reduced thickness. Computational fluid dynamic (CFD) simulations with FLUENT software are carried out to investigate the temperature field. And effects of oil inlet rate, oil inlet temperature, and erosion reduced thickness are examined. The presence of erosion pit brings about the obvious fluctuation of temperature drop along the extrados of bend. And the minimum temperature drop presents at the most severe erosion point. Small inlet temperature or large inlet velocity can lead to small temperature drop, while shallow erosion pit causes great temperature drop. The dimensionless minimum temperature drop is analyzed and the fitting formula is obtained. Using the formula we can calculate the erosion reduced thickness, which is only needed to monitor the outer surface temperature of bend pipe. This new method can provide useful guidance for pipeline monitoring and replacement. PMID:24719576

  16. Islands at bay: Rising seas, eroding islands, and waterbird habitat loss in Chesapeake Bay (USA)

    USGS Publications Warehouse

    Erwin, R.M.; Brinker, D.F.; Watts, B.D.; Costanzo, G.R.; Morton, D.D.

    2011-01-01

    Like many resources in the Chesapeake Bay region of the U. S., many waterbird nesting populations have suffered over the past three to four decades. In this study, historic information for the entire Bay and recent results from the Tangier Sound region were evaluated to illustrate patterns of island erosion and habitat loss for 19 breeding species of waterbirds. Aerial imagery and field data collected in the nesting season were the primary sources of data. From 1993/1994 to 2007/2008, a group of 15 islands in Tangier Sound, Virginia were reduced by 21% in area, as most of their small dunes and associated vegetation and forest cover were lost to increased washovers. Concurrently, nesting American black ducks (Anas rubripes) declined by 66%, wading birds (herons-egrets) by 51%, gulls by 72%, common terns (Sterna hirundo) by 96% and black skimmers (Rynchops niger) by about 70% in this complex. The declines noted at the larger Bay-wide scale suggest that this study area maybe symptomatic of a systemic limitation of nesting habitat for these species. The island losses noted in the Chesapeake have also been noted in other Atlantic U. S. coastal states. Stabilization and/or restoration of at least some of the rapidly eroding islands at key coastal areas are critical to help sustain waterbird communities. ?? 2010 US Government.

  17. The false claims act and the eroding scienter in healthcare fraud litigation.

    PubMed

    Doan, Richard

    2011-01-01

    This article addresses the federal government's expansive methods in tackling healthcare fraud, particularly in misapplying the False Claims Act. Although tasked with the obligation to curtail the fraudulent submission of Medicare & Medicaid claims, the U.S. government must rein in the current trend to utilize the False Claims Act against smaller medical providers. As the Act's original focus has ebbed in significance, the government has increasingly applied the False Claims Act to circumstances that do not evince actual fraud. In doing so, federal courts have effectively eroded the statute's critical scienter requirement. The federal common-law doctrines of "payment by mistake" and "unjust enrichment" adequately address the payment of non-fraudulent, albeit false, Medicare & Medicaid claims. Yet the federal government pursues these appropriate remedies only rarely and in the alternative, essentially when the government fails under the False Claims Act. Thus, this article argues for reform, calling for a clearer delineation between remedial and punitive measures. In cases involving smaller medical providers, courts should strictly limit the False Claims Act to those instances where fraud is clearly manifest.

  18. Effectiveness of incentives for agri-environment measure in Mediterranean degraded and eroded vineyards

    NASA Astrophysics Data System (ADS)

    Galati, Antonino; Gristina, Luciano; Crescimanno, Maria; Barone, Ettore; Novara, Agata

    2015-04-01

    The evaluation of the economic damage caused by soil erosion assumes great importance. It serves to increase awareness of the problem among farmers and policy makers. Moreover, it can promote the implementation of conservative measures at the field and basin level by spurring the development of more sustainable soil management practices. In the present study we have developed a new approach to evaluate the incentive for the adoption of Agri-Environment Measure (AEM) in Mediterranean degraded and eroded vineyards. In order to estimate this incentive, the replacement cost and the loss of income are calculated under two different soil management such as Conventional Tillage (CT) and Cover crop (AEM). Our findings show that the incentive could range between the loss of income due to AEM adoption and ecosystem service benefit (RCCT - RC AEM). In the case of study the incentive ranged between 315 € ha-1 (loss of income) and 1,087.86 € ha-1 (Ecosystem service benefit). Within this range, the incentive amount is determined according to efficiency criteria taking into account the morphological conditions of the territory in which operate the farms. Moreover, a conceptual model on the public spending efficiency has been developed to allocate the incentives where the economic return in term of ecosystem service is higher.

  19. The assessment of surface roughness and microleakage of eroded tooth-colored dental restorative materials

    PubMed Central

    Hussein, Thulfiqar Ali; Bakar, Wan Zaripah Wan; Ghani, Zuryati Ab; Mohamad, Dasmawati

    2014-01-01

    Objectives: To investigate the effect of acidic solution on surface roughness and microleakage of tooth-colored restorative materials. Materials and Methods: A 160 box-shaped cavities were prepared on the buccal surfaces of 160 human molars, and assigned to four groups: Group A restored with Ketac™ Molar Easymix, Group B with Fuji II™ LC, Group C with Ketac™ N100, and Group D with Filtek™ Z250, and subdivided into study and control groups (n = 20). Study groups were immersed in lemon juice (pH = 2.79) for 24 h, whilst controlgroups in deionized distilled water. All samples were immersed in 2% methylene blue dye, sectioned into two equal halves for surface roughness, and microleakage tests. Data were analyzed using Mann–Whitney and Kruskal–Wallis tests at P < 0.05. Results: There was a significant difference in surface roughness of Ketac™ Molar, Fuji II™ LC, and Ketac™ N100. No significant difference was found in microleakage of Ketac™ Molar and Fuji II™ LC; however, there were significant differences in the gingival margin of Ketac™ N100, and the occlusal margin of Filtek™ Z250. Conclusions: All glass ionomer cements were eroded after exposure to the acidic drink. Filtek™ Z250 and Ketac™ Molar Easymix showed more microleakage. All materials showed more microleakage at the gingival margins. PMID:25506139

  20. Diffuse-reflectance mid-infrared spectrocopy reveals chemical differences in soil organic matter carried in different size wind eroded sediments

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soil organic matter (SOM) influences water holding capacity, aggregation, and diversity. Little information is available regarding the C functional groups carried in wind eroded sediments away from the source soil. Mid-infrared (MidIR) spectra was used on wind tunnel-blown sediments eroded from a lo...

  1. Equilibrium Cross-section for River Channel with Cohesive Erodible Banks

    NASA Astrophysics Data System (ADS)

    Francalanci, S.; Lanzoni, S.; Macovei, D.; Solari, L.

    2012-12-01

    Bank erosion processes represent an important factor in driving planform changes, meander development and channel width adjustments in alluvial rivers. Recent literature of the last decade has shown that bank retreat process often involves combination of fluvial erosion and mass wasting, giving important contribution to the amount of sediment delivered downstream. In particular fluvial (or hydraulic) erosion involves the removal of bank materials by the direct erosive action of the flow, and it is one on the triggering factors of mass wasting such that the long-term rate of bank retreat is controlled by the rate of hydraulic erosion at the toe. A theoretical framework is here proposed to investigate the equilibrium cross-section in a river channel with cohesive erodible bank: the equilibrium width and the near-bank shear stress are predicted, given the channel and bank roughness characterization and the hydraulic variables which define the flow in the central region (slope, discharge, depth at bankfull condition). In this approach the solution for the flow obtained with a simple 1D model is coupled with a theoretical model to derive the boundary shear stress. The Kean and Smith (2006) model, which predicts the flow over the irregular bank topography that is characteristic of fine-grained riverbanks, provides a means to partition the form and skin drag components of bank boundary shear stress and thus determine the extent to which form drag influences bank erosion rates and channel equilibrium width. In this work, the hydraulic bank erosion rates are quantified using an excess shear stress formula; hence, the river channel is supposed to widen if the banks are unstable under the given hydraulic conditions, while the shape of the bank profile is conserved. The procedure is repeated until the equilibrium width associated with stable bank is reached. The results showed that form roughness induced by bank topographic features is a major component of the spatially

  2. Molecular and isotopic investigation of eroding reliefs of the East Siberian Arctic Coastal-Ice complex

    NASA Astrophysics Data System (ADS)

    Sánchez-García, L.; Vonk, J.; Alling, V.; Pugach, S.; van Dongen, B.; Charkin, A.; Kosmach, D.; Dudarev, O.; Semiletov, I.; Gustafsson, Ö.

    2010-05-01

    The Eurasian Arctic represents contains a vast stock of carbon in form of frozen loess deposits formed during the Last Glacial Maximum (~40,000 years ago): the so-called Yedoma or Ice Complex. The current global warming with particular influence on this area [1] is causing the thawing of the so far freeze-locked carbon deposits, remobilizing and releasing large amounts of carbon mainly as particulate organic carbon (POC) [2]. A combination of thermal collapse, sea-level rise and enhanced wave fetch from loss of coastal sea-ice cover, is causing accelerated coastal erosion of the Pleistocene Ice Complex [3]. Utilization of this old carbon, remobilized during the Ice Complex erosion by the microbial community present, would mean reintroduction of fossil forms of carbon in the short-term carbon cycle and potentially cause the release of greenhouse forms which, in turn, would trigger further warming. Our knowledge on the magnitude of the climatically-forced coastal erosion and the fate of the terrestrial OC once it enters the Arctic Ocean is still very limited. This study aims to approach these questions, studying a well known case of coastal erosion (retreat rate up to 20 m/y over last decade) in the Eurasian Arctic Shelf (EAS): The island of Muostakh (SE Laptev Sea). Soil samples (n=11) were collected from Muostakh in 2006 along 4 'erosion transects', in order to characterize the eroded material in terms of organic carbon (OC) content, bulk 14C-based age and lipid biomarkers composition (n-alkanes, n-alkanoic acids, n-alkanols, sterols). On-site CO2 measurements were carried out on similar surface, to detect degradation signals. To elucidate what happens with the eroded OC once it enters the shelf, seawater samples (n=218) were collected at different depths from 94 sites on the EAS samples, as part of the ISSS-08 (International Siberian Shelf Study, 2008) sampling program. The distribution and composition of POC was studied in relation with other water column

  3. The role of constructed wetlands in sequestering eroded carbon in an agricultural landscape.

    NASA Astrophysics Data System (ADS)

    Maynard, J. J.; O'Geen, A. T.; Dahlgren, R. A.

    2008-12-01

    The fate of carbon lost by erosion is not well understood in agricultural settings. Recent models suggest that wetlands and other small water bodies may serve as important long-term sinks of eroded carbon. An estimated 2.6 million small (less than 104 m2), artificial water bodies (e.g. water catchment reservoirs, farm ponds, and wetlands) are scattered across the United States. These areas are estimated to receive one third of all eroded materials. Consequently, carbon accumulation in small subaqueous environments may have a significant effect on carbon storage. The conversion of marginal farmland to constructed and restored wetlands is a growing land use in California's Central Valley. Many of these systems receive agricultural runoff as their main water supply, which is rich in suspended sediment and nutrients. This study examined the potential for carbon sequestration in an eight-year-old seasonally saturated constructed wetland that receives tailwater from over 4,000 acres of farmland. The temporal and spatial dynamics of carbon and sediment accumulation were evaluated by employing a spatially explicit sampling design to measure net sedimentation and net above-ground biomass in 2004 and 2005. Additionally, in 2006, sediment cores were collected to the antecedent (time zero) soil layer, which ranged between 2 and 50 cm below the surface. The spatial variability of carbon and sediment accumulation was modeled with geostatistics. Average sediment accumulation rate, nearly doubled from 2004 to 2005, with rates of 5.8 kg m-2 y-1 (range: 0-80 kg m-2 y-1) in 2004 and 11.9 kg m-2 y-1 (range: 0-93 kg m2 y-1) in 2005. Average carbon accumulation rate did not change between years, with rates of 0.290 kg m-2 y-1 in 2004 and 0.294 kg m-2 y-1 in 2005, indicating a change in carbon source between years. Average total carbon content of soils in the contributing watershed is 8 g kg-1, whereas average carbon content of inflowing sediment was 14 g kg-1, resulting in an enrichment

  4. The fate of residual carbon in floodplain sediments, originating from eroding peatlands

    NASA Astrophysics Data System (ADS)

    Alderson, Danielle; Evans, Martin; Rothwell, James; Boult, Stephen; Rhodes, Edward

    2016-04-01

    Fluvial systems and their associated sediments have been overlooked as part of global carbon budgets until recently. In the UK, large stores of organic carbon in peatlands are dynamically eroding, with the eventual result being 'off-site' greenhouse gas emissions, which must be incorporated into carbon budgets for management strategies. Evans et al. (2013) concluded peatland fluvial systems are active cyclers of carbon, with 50-90% of particulate organic carbon (POC) exported from peatlands eventually emitted as CO2. Floodplains, although commonly regarded as zones of carbon storage, have been identified as potential hotspots of carbon cycling in the fluvial system with a key process being decomposition of POC. Only 20% of POC may escape mineralisation on floodplains within a peatland catchment (Evans et al., 2013), but studying the composition of the residual carbon has the potential to add to understanding of the drivers of storage versus mineralisation. In this research we have examined stratigraphic records of carbon cycling by focusing on organic matter preserved in a floodplain environment downstream of the Bleaklow Plateau in the Peak District. An OSL date of 640 +/- 90 years BP and a radiocarbon date of 500-310 cal years BP from the sediment cores collected, together with an assessment of the valley morphology using high resolution LiDAR DEM's, indicate potential interaction of post glacial landslide features with the onset of substantial peat erosion, conditioning the landscape to interrupt the transport of carbon down the fluvial network. Floodplain cores have been correlated on the basis of both visual stratigraphy and geochemistry obtained by Itrax core scanning. This data is supported by targeted gas flux data from boreholes using a Gasclam. We present a rudimentary carbon budget for the floodplain of study.

  5. Hyperdopaminergic Tone Erodes Prefrontal LTP via a D2 Receptor-operated Protein Phosphatase Gate

    PubMed Central

    Xu, Tai-Xiang; Sotnikova, Tatyana D.; Liang, Chengyu; Zhang, Jingping; Jung, Jae U.; Spealman, Roger D.; Gainetdinov, Raul R.; Yao, Wei-Dong

    2009-01-01

    Dopamine (DA) plays crucial roles in the cognitive functioning of the prefrontal cortex (PFC), which, to a large degree, depends on lasting neural traces formed in prefrontal networks. The establishment of these permanent traces requires changes in cortical synaptic efficacy. DA, via the D1-class receptors, is thought to gate or facilitate synaptic plasticity in the PFC, with little role recognized for the D2-class receptors. Here we show that, when significantly elevated, DA erodes, rather than facilitates, the induction of long-term potentiation (LTP) in the PFC by acting at the far less abundant cortical D2-class receptors through a dominant coupling to the protein phosphatase 1 (PP1) activity in postsynaptic neurons. In mice with persistently elevated extracellular DA, resulting from inactivation of the DA transporter (DAT) gene, LTP in layer V PFC pyramidal neurons can not be established, regardless of induction protocols. Acute increase of dopaminergic transmission by DAT blockers or overstimulation of D2 receptors in normal mice have similar LTP shut-off effects. LTP in mutant mice can be rescued by a single in vivo administration of D2-class antagonists. Suppression of postsynaptic PP1 mimics and occludes the D2-mediated rescue of LTP in mutant mice, and prevents the acute erosion of LTP by D2 agonists in normal mice. Our studies reveal a mechanistically unique heterosynaptic PP1 gate that is constitutively driven by background DA to influence LTP induction. By blocking prefrontal synaptic plasticity, excessive DA may prevent storage of lasting memory traces in PFC networks and impair executive functions. PMID:19906957

  6. Geophysical Survey and Detailed Geologic Mapping of an Eroded Stratovolcano's Central Intrusive Complex, Summer Coon, Co.

    NASA Astrophysics Data System (ADS)

    Harp, A.

    2015-12-01

    Eroded volcanoes expose plumbing systems that provide important information on intrusive geometries, magma propagation directions, and the effects of host rock types and heterogeneities. Summer Coon Volcano, CO, is an Oligocene stratovolcano where erosion has removed much of the original edifice, revealing the intrusive stocks of the central intrusive complex (CIC). Surrounding the CIC are hundreds of radial dikes ranging from basaltic to rhyolitic in composition. Published geologic maps indicate most radial dikes do not connect to the intrusive stocks, supporting published theories that most did not emanate from the central intrusions. However, much of the area surrounding the CIC is covered by alluvium, suggesting that the lack of connection might be an artifact of exposure. We completed a ground magnetic survey and detailed geological mapping to determine if the dikes continue beneath the alluvium and into the intrusive stocks. Linear magnetic anomalies indicate four NW-SE trending rhyodacite dikes continue beneath the alluvium for up to 250 m, and mapping indicates that at least two of the rhyodacite dikes do extend into the CIC. Shorter linear anomalies are attributed to seven NW-SE trending basaltic dikes ~100-500-m-long which are sparsely exposed in the alluvium. Mapping shows that three rhyodacite dikes extend into the CIC and to within 200 m of their possible source, an 800-m-wide granodiorite stock. Additionally, three rhyolitic dikes extend to within several meters of a 200×500-m-wide tuff breccia zone of similar composition, likely their source. In summary, magnetic data and detailed mapping indicate that radial dikes do extend into the central intrusive complex in contrast to some model predictions.

  7. Rapidly eroding piñon-juniper woodlands in New Mexico: response to slash treatment.

    PubMed

    Hastings, Brian K; Smith, Freeman M; Jacobs, Brian F

    2003-01-01

    The piñon (Pinus edulis Engelm.)-juniper [Juniperus monosperma (Engelm.) Sarg.] woodlands of Bandelier National Monument are experiencing accelerated erosion. Earlier studies suggest that causes of these rapidly eroding woodlands are related to an unprecedented rapid transition of ponderosa pine (Pinus ponderosa C. Lawson) savanna to piñon-juniper woodlands as a result of cumulative historical effects of overgrazing, fire suppression, and severe drought. To study the effectiveness of slash treatment in reducing accelerated erosion, we used sediment check dams to quantify sediment yield from twelve paired microwatersheds (300-1100 m2) within an existing paired water-shed study. Six of the twelve microwatersheds were located in a 41-ha (treatment) watershed with scattered slash treatment, whereas six microwatersheds were located in an adjacent 35-ha untreated (control) watershed. The primary purpose of our research was to quantify the rates of sediment yield between the treated and control microwatersheds. Sediment yield was measured from 15 individual storms during the months of June-September (2000 and 2001). In response to slash treatment, mean seasonal sediment yield for 2000 equaled 2.99 Mg/ha in the control vs. 0.03 Mg/ha in the treatment and 2.07 Mg/ha in the control vs. 0.07 Mg/ha in the treatment in 2001. The practice of slash treatment demonstrates efficacy in reducing erosion in degraded piñon-juniper woodlands by encouraging herbaceous recovery. Our data show that slash treatment increases total ground cover (slash and herbaceous growth) beyond a potential erosion threshold. Restored piñon-juniper woodlands, as the result of slash treatment, provide a forest structure similar to pre-grazing and pre-fire suppression conditions and decrease catastrophic fire hazard. PMID:12931884

  8. Reconstructing eroded paleovolcanoes on Gran Canaria, Canary Islands, using advanced geomorphometry

    NASA Astrophysics Data System (ADS)

    Karátson, D.; Yepes, J.; Favalli, M.; Rodríguez-Peces, M. J.; Fornaciai, A.

    2016-01-01

    Original volcanic edifices of two successive stages of Gran Canaria are reconstructed using a geomorphometric analysis of existent or restored paleosurfaces. In the reconstruction, surface fitting was applied preferably to planèzes (i.e. triangular facets of original volcano flanks) and quasi-planar surfaces, QPS (those occurring on planèzes, or scattered, slightly eroded portions derived from original cone surfaces) with the help of red relief image map (RRIM) analysis. Out of the long-lasting, Mid-Miocene to Holocene subaerial evolution of the island, the Late Miocene Fataga volcano and the subsequent, Pliocene Roque Nublo volcanoes were the largest and highest. The eruptive center of Fataga, a composite edifice (12.2-8.8 Ma) that may have grown up excentrically with respect to the previous Tejeda caldera, is well-defined by both two planèzes (named Veneguera-Mogán and Fataga-Tirajana) and QPS remnants. Its calculated original volume, ≤ 1000 km3, is close to the largest stratovolcanoes on Earth. However, its ≥ 3300 m elevation, obtained by exponential fit, may have been significantly lower due to the complex architecture of the summit region, e.g. a caldera responsible for ignimbrite eruptions. Roque Nublo, a 3.7-2.9 Ma stratovolcanic cone, which was superimposed upon the Fataga rocks ≥ 3 km west of the Fataga center, has left no considerable paleosurfaces behind due to heavy postvolcanic erosion. Yet, its remnant formations preserved in a radial pattern unambiguously define its center. Moreover, surface fitting of the outcropping rocks can be corrected taking the erosion rate for the past 3 Ma into account. Such a corrected surface fit points to a regular-shaped, ≥ 3000 m-high cone with a 25 km radius and ca. 940 km3 original volume, also comparable with the dimensions of the largest terrestrial stratovolcanoes.

  9. Freeze-drying processes and wind erodibility of a clay loam soil in southern Alberta

    SciTech Connect

    Bullock, M S.; Larney, F. J.; McGinn, Sean M.; Izaurralde, R Cesar C.

    1999-01-01

    Freeze-drying has been implicated as a factor causing soil aggregate breakdown on the Canadian Prairies and northern Great Plains. Aggregates of a Dark Brown Chernozemic clay loam soil sampled in October 1993 and January and April 1994 were subjected to repeated cycles of wetting (to 0.1, 0.2 and 0.3 kg kg-1 water contents) freezing, and freeze-drying under laboratory conditions. The October 1993 samples showed less disruption when initially exposed to freeze-drying cycles compared to samples taken in January and April 1994. Using regression analysis, we predicted that 31 freeze-dry cycles were required for the 0.1 kg kg-1 water content aggregates to reach 60% erodible fraction (EF, % aggregates <0.86 mm), 9 cycles for the 0.2 kg kg-1 aggregates and 2 for 0.3 kg kg-1 aggregates. In a field study, conducted over the 1994-1995 winter on a similar clay loam soil, we estimated the number of freeze-drying cycles using large vapor pressure (VPL) and small vapor pressure (VPS) gradients bet ween the soil surface (which had a mean winter water content of {approx}0.1 kg kg-1) and the atmosphere. With solar energy adjustments, we predicted that the number of freeze-dry cycles required for the soil to reach 60% EF was 60 for VPL and 37 for VPS conditions. The latter number was similar to the 31 cycles predicted in the laboratory study of aggregates at 0.1 water content. Our results demonstrate that freeze-drying is an important overwinter process in the breakdown of soil aggregates and hence wind erosion risk in the Canadian prairie region.

  10. Characterization of Primary, Eroded, and Mantled Volcanic Surfaces Using Data Fusion

    NASA Astrophysics Data System (ADS)

    Byrnes, J. M.; Finnegan, D. C.; Ramsey, M. S.; Anderson, S. W.

    2005-12-01

    Volcanic surface units, including lava flows and pyroclastic materials forming plains and edifices, are widespread on the surfaces of rocky planetary bodies. Understanding the formation and degradation processes that produce and modify such geologic units is crucial to understanding the geologic evolution of these bodies. In order to characterize primary, eroded, and mantled characteristics of volcanic surfaces, we are utilizing a data fusion approach to examining the Amboy Crater cinder cone and lava flow field. Located in the Mojave Desert in southern California, this volcanic complex is roughly 80 ka in age and covers approximately 70 sq. km. Amboy Crater is a particularly desirable study site because it displays a wide range of volcanic features that have been subjected to various extents of erosion and mantling from aeolian and fluvial activity, and because it is an excellent terrestrial analog for Mars. Our approach uses a suite of complementary datasets that has been collected for Amboy Crater, including airborne LIDAR (light detection and ranging) and radar (radio detection and ranging) data, and airborne and spaceborne visible and near infrared (VNIR), shortwave infrared (SWIR), and thermal infrared (TIR) data. Quantitative comparison of these remote sensing datasets acquired at a range of spatial resolutions provides constraints on the ability to discriminate various morphologic and spectral characteristics of exposed surface units. In conjunction with field analyses, these comparisons provide means to remotely identify topographic and spectral signatures that are diagnostic of volcanic and degradational processes. Processes examined within the study area include lava flow emplacement and inflation, emplacement of lava cinders and spatter, erosion of the lava flows and cinder cone by liquid flow and sandblasting, and deposition of airborne and waterborne sediments.

  11. Soil profile dynamics in an eroding soil landscape - a catena through a kettle hole

    NASA Astrophysics Data System (ADS)

    Gerke, Horst H.; Kaczorek, Danuta; Hierold, Wilfried; Deumlich, Detlef; Koszinski, Sylvia; Ellerbrock, Ruth H.; Sommer, Michael

    2015-04-01

    The arable hummocky ground moraine soil landscapes are characterized by a spatial continuum of more or less eroded soils at hilltops and slopes, and by colluviated soils in topographic depressions. After removal of forest in the middle ages, colluvium started covering the pre-existing Histosols and Gleysols within and Luvisols in the vicinity of kettle holes. A catena through originally peat-filled kettle-hole has hardly been described with respect to ongoing pedological modifications according to changes in landscape and hydrology. The objective was to derive the lateral continuum of soil horizons by identifying the location of the lateral boundaries between regions of clay mobilization/migration and gleisation (gleyic conditions), peat accumulation, and secondary carbonate accumulation. Data from an intensively-sampled field in northeastern Germany are presented. The start of colluviation could be dated by tree ring analyses of a buried stem. The location of the fossil topsoil A and peat horizons was determined from a dense grid of auger holes and geophysical explorations. In addition to older processes in the landscape, also younger redoximorphic processes were indicating changes in soil hydraulic properties and a modified hydrology of the arable soil landscape. We found in micromorphological analyses of soil thin sections that clay migration is an ongoing process; samples indicated vertical gradients in C-contents and secondary carbonate accumulation. The clay mobilization in the colluvium and the migration into the fossil horizons seemed to depend on the direction of soil water movement; anisotropic hydraulic conductivity indicated a potential for lateral water movement. The catena data suggest that the soil landscape development was relatively dynamic; the results may allow the reconstruction of former land surfaces, soil distributions, and erosion rates and may help predicting future developments.

  12. Modification of the USLE K factor for soil erodibility assessment on calcareous soils in Iran

    NASA Astrophysics Data System (ADS)

    Ostovari, Yaser; Ghorbani-Dashtaki, Shoja; Bahrami, Hossein-Ali; Naderi, Mehdi; Dematte, Jose Alexandre M.; Kerry, Ruth

    2016-11-01

    The measurement of soil erodibility (K) in the field is tedious, time-consuming and expensive; therefore, its prediction through pedotransfer functions (PTFs) could be far less costly and time-consuming. The aim of this study was to develop new PTFs to estimate the K factor using multiple linear regression, Mamdani fuzzy inference systems, and artificial neural networks. For this purpose, K was measured in 40 erosion plots with natural rainfall. Various soil properties including the soil particle size distribution, calcium carbonate equivalent, organic matter, permeability, and wet-aggregate stability were measured. The results showed that the mean measured K was 0.014 t h MJ- 1 mm- 1 and 2.08 times less than the estimated mean K (0.030 t h MJ- 1 mm- 1) using the USLE model. Permeability, wet-aggregate stability, very fine sand, and calcium carbonate were selected as independent variables by forward stepwise regression in order to assess the ability of multiple linear regression, Mamdani fuzzy inference systems and artificial neural networks to predict K. The calcium carbonate equivalent, which is not accounted for in the USLE model, had a significant impact on K in multiple linear regression due to its strong influence on the stability of aggregates and soil permeability. Statistical indices in validation and calibration datasets determined that the artificial neural networks method with the highest R2, lowest RMSE, and lowest ME was the best model for estimating the K factor. A strong correlation (R2 = 0.81, n = 40, p < 0.05) between the estimated K from multiple linear regression and measured K indicates that the use of calcium carbonate equivalent as a predictor variable gives a better estimation of K in areas with calcareous soils.

  13. Ecologically asynchronous agricultural practice erodes sustainability of the Loess Plateau of China.

    PubMed

    Wang, Tianming; Wu, Jianguo; Kou, Xiaojun; Oliver, Chadwick; Mou, Pu; Ge, Jianping

    2010-06-01

    Sustainability of agricultural landscapes depends largely on land-use practices. As one of the most productive and widespread agricultural soils, loess is often deep and easily eroded, posing grand challenges for environmental sustainability around the world. One prime example is the Loess Plateau of China, which has been cultivated for more than 7500 years. Based on long-term data sets, this study demonstrates that the dominant agricultural practice, winter wheat cropping, continues to be the primary driver for the massive soil erosion and landscape modifications on the Loess Plateau. This traditional farming system is asynchronous with the dynamic rhythm between natural vegetation and climate in the region. In particular, the long summer fallow period for winter wheat fields is concurrent with the heavy-rainstorm season, which greatly accelerates soil erosion. Our finding indicates that common land-use practices that have lasted for thousands of years in China are not environmentally sustainable. Agriculture in this region has relied primarily on the continuous "mining" of the soil for the past several thousand years but does not have a one-thousand-year future because of myriad environmental and socioeconomic factors associated with soil erosion. To contain soil erosion and promote sustainability on the Loess Plateau, therefore, a change in the agricultural regime is needed to make sure that current and future agricultural practices follow the vegetation-climate rhythm. In addition, to achieve environmental, economic, and social sustainability in this region, multifunctional land-use planning is required to increase landscape diversity and functions (e.g., proper arrangement of crop fields, orchards, and protected areas).

  14. Rapidly eroding piñon-juniper woodlands in New Mexico: response to slash treatment.

    PubMed

    Hastings, Brian K; Smith, Freeman M; Jacobs, Brian F

    2003-01-01

    The piñon (Pinus edulis Engelm.)-juniper [Juniperus monosperma (Engelm.) Sarg.] woodlands of Bandelier National Monument are experiencing accelerated erosion. Earlier studies suggest that causes of these rapidly eroding woodlands are related to an unprecedented rapid transition of ponderosa pine (Pinus ponderosa C. Lawson) savanna to piñon-juniper woodlands as a result of cumulative historical effects of overgrazing, fire suppression, and severe drought. To study the effectiveness of slash treatment in reducing accelerated erosion, we used sediment check dams to quantify sediment yield from twelve paired microwatersheds (300-1100 m2) within an existing paired water-shed study. Six of the twelve microwatersheds were located in a 41-ha (treatment) watershed with scattered slash treatment, whereas six microwatersheds were located in an adjacent 35-ha untreated (control) watershed. The primary purpose of our research was to quantify the rates of sediment yield between the treated and control microwatersheds. Sediment yield was measured from 15 individual storms during the months of June-September (2000 and 2001). In response to slash treatment, mean seasonal sediment yield for 2000 equaled 2.99 Mg/ha in the control vs. 0.03 Mg/ha in the treatment and 2.07 Mg/ha in the control vs. 0.07 Mg/ha in the treatment in 2001. The practice of slash treatment demonstrates efficacy in reducing erosion in degraded piñon-juniper woodlands by encouraging herbaceous recovery. Our data show that slash treatment increases total ground cover (slash and herbaceous growth) beyond a potential erosion threshold. Restored piñon-juniper woodlands, as the result of slash treatment, provide a forest structure similar to pre-grazing and pre-fire suppression conditions and decrease catastrophic fire hazard.

  15. Soil aggregates, organic matter turnover and carbon balance in a Mediterranean eroded vineyard

    NASA Astrophysics Data System (ADS)

    Novara, Agata; Lo Papa, Giuseppe; Dazzi, Carmelo; Gristina, Luciano; Cerdà, Artemi

    2014-05-01

    The carbon cycle is being affected by the human impacts (Novara et al., 2011; Yan-Gui et al., 2013), and one of those is the intensification in the soil erosion in agriculture land (Cerdà et al., 2009; García Orenes et al., 2009). Vineyards also are affected by the human activities (Fernández Calviño, 2012). Vineyards in Sicily are cultivated on 110.000 ha, 10% of which on >10% slope. Deficiencies of soil organic matter are typical of the semi arid Mediterranean environment especially where traditional intensive cropping practices are adopted (Novara et al., 2012; 2013). These practices in vineyards could lead soil to intensive erosion processes (Novara et al., 2011). The fate of SOC under erosion processes is difficult to understand because of the influence of the erosion impact on SOC pathway, which depends on the different features of the process involved (detachment, transport and/or deposition). Soil erosion must be considered a net C source (Lal, 2003), as eroded soils have lower net primary productivity (NPP) (Dick and Gregorich, 2004) caused by reduction in the effective rooting depth and all in all determining decline in soil quality. Breakdown of aggregates and soil dispersion expose SOM to microbial/enzymatic processes and chemical soil properties (Dimoyiannis, 2012; Kocyigit and Demirci, 2012). Moreover the light fraction, transported by runoff, is labile and easily mineralized determining CO2 emission in the atmosphere (Jacinthe and Lal, 2004). Therefore, the carbon pool is lower in eroded than in un-eroded soil scapes and the rate of mineralization of soil organic matter is higher in sediments than in original soil. In this survey we show a research conducted on a slope sequence of three soil profiles in an irrigated vineyard located in Sambuca di Sicilia, Italy (UTM33-WGS84: 4169367N; 325011E). The SOC content was measured at depth intervals of 10 cm up to a depth of 60 cm in each pedon. Wet aggregate-size fractions with no prior chemical

  16. Land degradation assessment by geo-spatially modeling different soil erodibility equations in a semi-arid catchment.

    PubMed

    Saygın, Selen Deviren; Basaran, Mustafa; Ozcan, Ali Ugur; Dolarslan, Melda; Timur, Ozgur Burhan; Yilman, F Ebru; Erpul, Gunay

    2011-09-01

    Land degradation by soil erosion is one of the most serious problems and environmental issues in many ecosystems of arid and semi-arid regions. Especially, the disturbed areas have greater soil detachability and transportability capacity. Evaluation of land degradation in terms of soil erodibility, by using geostatistical modeling, is vital to protect and reclaim susceptible areas. Soil erodibility, described as the ability of soils to resist erosion, can be measured either directly under natural or simulated rainfall conditions, or indirectly estimated by empirical regression models. This study compares three empirical equations used to determine the soil erodibility factor of revised universal soil loss equation prediction technology based on their geospatial performances in the semi-arid catchment of the Saraykoy II Irrigation Dam located in Cankiri, Turkey. A total of 311 geo-referenced soil samples were collected with irregular intervals from the top soil layer (0-10 cm). Geostatistical analysis was performed with the point values of each equation to determine its spatial pattern. Results showed that equations that used soil organic matter in combination with the soil particle size better agreed with the variations in land use and topography of the catchment than the one using only the particle size distribution. It is recommended that the equations which dynamically integrate soil intrinsic properties with land use, topography, and its influences on the local microclimates, could be successfully used to geospatially determine sites highly susceptible to water erosion, and therefore, to select the agricultural and bio-engineering control measures needed.

  17. Screening of POP pollution by AChE and EROD activities in Zebra mussels from the Italian Great Lakes.

    PubMed

    Binelli, A; Ricciardi, Francesco; Riva, Consuelo; Provini, Alfredo

    2005-12-01

    The increase of ethoxyresorufin dealkylation (EROD) and the inhibition of acetylcholinesterase (AChE) as biomarkers have been commonly used in vertebrates for the persistent organic pollutants (POPs) biomonitoring of aquatic environments, but very few studies have been performed for invertebrates. Previous researches demonstrated the interference due to some chemicals on EROD and AChE activities of the freshwater bivalve Zebra mussel (Dreissena polymorpha) in laboratory and field studies, showing its possible use for the screening of POP effects. We investigated the contamination of the Italian sub-alpine great lakes (Maggiore, Lugano, Como, Iseo, Garda) by the biomarker approach on Zebra mussel specimens collected at 17 sampling sites with different morphometric characteristics and anthropization levels. Results showed a homogeneous contamination of AChE inhibitors in Lake Garda, Maggiore, Como and Iseo with values ranging from 0.5 to 3 nmol/min/mg proteins and with an average inhibition of about 66% to controls. The planar compounds pollution, able to activate the EROD activity, seems higher in some sampling stations of Lake Garda, Como and Iseo (2-4 pmol/min/mg proteins) than that measured in Lake Lugano (1.5-3 pmol/min/mg proteins). On the contrary, the enzyme activity in Lake Maggiore showed an interesting opposite effect of AhR-binding compounds and trace metals. Finally, the possible use of Zebra mussel specimens maintained at laboratory conditions as controls against the selection of the less polluted sampling site is discussed.

  18. Improving the in vitro ethoxyresorufin-O-deethylase (EROD) assay with RTL-W1 by metabolic normalization and use of β-naphthoflavone as the reference substance.

    PubMed

    Heinrich, Patrick; Diehl, Ulrike; Förster, Franziska; Braunbeck, Thomas

    2014-08-01

    The ethoxyresorufin-O-deethylase (EROD) assay is a widely applied method for the evaluation of the dioxin-like activity of single substances and environmental samples. As for most enzyme assays, the specific activity is normally related to total protein contents, the determination of which has clear limitations in high-throughput assays. EROD induction potentials are usually expressed as 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) equivalents, a substance highly toxic to humans. In order to compensate for these shortcomings, two modifications of the EROD protocol are proposed: (1) EROD activity is normalized to the metabolic activity of the cells as determined by a modified thiazolyl blue tetrazolium (MTT) assay and expressed as metabolic cell equivalents (MCE) based on MTT data rather than to protein contents. Via MCE data, cytotoxicity information can always be reported in parallel to EROD data; with the protocol presented here, MTT and EROD data are collected simultaneously. (2) Among several reference substances tested (2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), β-naphthoflavone and benzo[a]pyrene), β-naphthoflavone proved to be the most suitable reference for the routine in vitro EROD assay, although TCDD has generally been preferred for purely scientific reasons.

  19. Soil aggregates, organic matter turnover and carbon balance in a Mediterranean eroded vineyard

    NASA Astrophysics Data System (ADS)

    Novara, Agata; Lo Papa, Giuseppe; Dazzi, Carmelo; Gristina, Luciano; Cerdà, Artemi

    2014-05-01

    The carbon cycle is being affected by the human impacts (Novara et al., 2011; Yan-Gui et al., 2013), and one of those is the intensification in the soil erosion in agriculture land (Cerdà et al., 2009; García Orenes et al., 2009). Vineyards also are affected by the human activities (Fernández Calviño, 2012). Vineyards in Sicily are cultivated on 110.000 ha, 10% of which on >10% slope. Deficiencies of soil organic matter are typical of the semi arid Mediterranean environment especially where traditional intensive cropping practices are adopted (Novara et al., 2012; 2013). These practices in vineyards could lead soil to intensive erosion processes (Novara et al., 2011). The fate of SOC under erosion processes is difficult to understand because of the influence of the erosion impact on SOC pathway, which depends on the different features of the process involved (detachment, transport and/or deposition). Soil erosion must be considered a net C source (Lal, 2003), as eroded soils have lower net primary productivity (NPP) (Dick and Gregorich, 2004) caused by reduction in the effective rooting depth and all in all determining decline in soil quality. Breakdown of aggregates and soil dispersion expose SOM to microbial/enzymatic processes and chemical soil properties (Dimoyiannis, 2012; Kocyigit and Demirci, 2012). Moreover the light fraction, transported by runoff, is labile and easily mineralized determining CO2 emission in the atmosphere (Jacinthe and Lal, 2004). Therefore, the carbon pool is lower in eroded than in un-eroded soil scapes and the rate of mineralization of soil organic matter is higher in sediments than in original soil. In this survey we show a research conducted on a slope sequence of three soil profiles in an irrigated vineyard located in Sambuca di Sicilia, Italy (UTM33-WGS84: 4169367N; 325011E). The SOC content was measured at depth intervals of 10 cm up to a depth of 60 cm in each pedon. Wet aggregate-size fractions with no prior chemical

  20. The evolution of stream coupled hillslopes by bedrock landsliding in a rapidly eroding mountain belt, Taiwan

    NASA Astrophysics Data System (ADS)

    Wenske, Dirk; Jen, Chia-Hung; Böse, Margot; Lin, Jiun-Chuan

    2010-05-01

    Being affected frequently by violent weather condition such as typhoons and regular seismic activity, the high mountains of Taiwan belong to the earth's most dynamic landscapes. In the fast-eroding mountain belt of Taiwan, hillslopes and valley systems have been reported to show a high level of coupling (Hovius et al. 2000). In the catchment of the Tachia river numerous bedrock landslides occur frequently as a result of seismic events and typhoons (Lin et al. 2006). This study attempts to take a closer look at the temporal and spatial pattern of hillslope evolution at two study sites in the upper catchement of the Tachia river. Therefore we have carried out a repeated field surveying of active slopes by means of traditional survey instruments and terrestrial laser scanning from early 2008 until late 2009 on a half year basis. Additionally, a set of aerial photos and satellite images from 1969, 1980,2001, 2004, 2007, 2008 and 2009 is used to assess the long-term and short-term changes of the river channel. Near the town of Huan Shan, the valley bottom shows elevations around 1520 m above sea level and the river is draining and upstream area of 155 km². Downstream of Huan Shan lies the confluence of the Tachia River and two of its tributaries, namely the Nanhu River and the Hehuan River. Therefore, the catchment area upstream of second study area in Sung Mao is considerably larger being of 420 km², in that place, the current level of the channel varies around 1425 m above sea level. In the two study areas strong lateral erosion has been observed. In the case of the Sung Mao study area, the latter is linked to a severe aggradation of sediments in the channel since the building of the Dechi Dam downstream. The active hillslopes have been surveyed and their reaction to the typhoons in 2008 and 2009 is studied. Rates of sediment yield from the slopes have been calculated for three periods between April 2008, November 2008, April 2009 and November 2009. Furthermore, the

  1. Effect of biocrust: study of mechanical and hydraulic properties and erodibility

    NASA Astrophysics Data System (ADS)

    Slavík, Martin; Bruthans, Jiří; Schweigstillová, Jana

    2016-04-01

    It is well-known that lichens and other organisms forming crust on soil or rock surface play important role in weathering but may also protect underlying material from fast erosion. So far, there have been only few measurements comparing mechanical or hydraulic properties of biocrust with its subsurface on locked sand and friable sandstones, so the overall effect of the biocrust is not well-understood. Objective of our study is to quantify the effect of the biocrust on mechanical and hydraulic properties of friable sandstone and locked sand of Cretaceous age in six different localities with varying aspect and inclination and age of exposure in sandpit Strelec (Czech Rep.). On the artificial exposures, biocrust developed within last 10-30 years. Beside measurements of mechanical and hydraulic properties, SEM and mercury intrusion porosimetry in crust and subsurface was performed. Drilling resistance technique was found an excellent method to distinguish the biocrust from its subsurface (~3 mm thick biocrust has up to 12 times higher drilling resistance than underlying material). Surface zone with the biocrust has 3 - 25 times higher tensile strength than the subsurface material (1 - 25 kPa). In comparison with the subsurface, the biocrust is considerably less erodible (based on water jet testing). Biocrust saturated hydraulic conductivity is 15 - 240 times lower than the subsurface (6*10 -5 - 1*10 -4 m/s) and its permeability for water vapor is 4 - 9 times lower than subsurface. Presence of the biocrust slows down capillary absorption of water 4 - 25 times. The biocrust is thus forming firm surface which protects underlying material from rain and flowing water erosion and which considerably modifies its hydraulic properties. Material with crust exposed to calcination, leaching by concentrated peroxide and experiments with zymoliase enzyme strongly indicate that major contribution to crust hardening is provided by organic matter. Based on DNA sequencing the crust is

  2. Turnover of eroded soil organic carbon after deposition in terrestrial and aquatic environments

    NASA Astrophysics Data System (ADS)

    Kirkels, Frédérique; Cammeraat, Erik; Kalbitz, Karsten; van Oost, Kristof; Ellerbrock, Ruth; Follain, Stéphane; Fuchslueger, Lucia; Gerke, Horst; Heckrath, Goswin; Kögel-Knabner, Ingrid; Kuhn, Nikolaus; van Loon, Emiel; Quinton, John; Richter, Andreas; Salvador-Blanes, Sébastien; Sommer, Michael; Steffens, Markus

    2015-04-01

    The fate of eroded soil organic carbon (SOC) after deposition is a large uncertainty in assessing the impact of soil erosion on C budgets. Globally, large amounts of SOC are transported by erosion and a substantial part is transferred into adjacent inland waters, linking terrestrial and aquatic C cycling. However, the net effect on C fluxes between soils, inland waters and atmosphere remains uncertain. In this study, we determined SOC turnover in terrestrial and aquatic environments and indentified its major controls. A European gradient of agricultural sites was sampled, spanning a wide range soil properties (e.g. texture, aggregation, etc.), SOC quantity and quality. In a 16-week incubation experiment, SOC turnover was determined for conditions reflecting downslope soils or inland waters. Moreover, we studied the impact of labile C inputs ('priming') on SOC stability using 13C labeled cellulose. Physical and chemical soil properties and SOC molecular composition were assessed as potential controls on C turnover. SOC deposition in aquatic environments resulted in upto 3.5 times higher C turnover than deposition on downslope soils. Labile C inputs enlarged total CO2 emissions, with the largest increase for aquatic conditions. Solid-state 13C NMR and FT-IR spectroscopy showed broad similarities in SOC molecular composition. Soil and SOC properties could not (yet) fully explain variation in SOC turnover between the sites. However, temporal trends in CO2 emissions clearly differed between downslope soils and inland waters. We established a quantitative model, based on the ten sites of the European gradient, that is capable to describe CO2 emissions for SOC deposited on soils and in inland waters and upon different levels of labile C inputs. Our findings indicate that deposition conditions (soils vs. inland waters) play a crucial role in determining C turnover. Erosion measures preventing deposition in aquatic environments could therefore be an important carbon saving

  3. Improving the spatio-temporal erodibility of dust emission models using MODIS data (Invited)

    NASA Astrophysics Data System (ADS)

    Chappell, A.

    2013-12-01

    Wind erosion and dust emission models are essential to estimate the lateral and vertical fluxes of carbon and nutrients between terrestrial and marine ecosystems and reduce uncertainty about dust radiative forcing of climate models. Wind erosion models approximate turbulent transfer of momentum by surface roughness elements using roughness density (lateral cover or the frontal area index; λ). Raupach et al. (1993) demonstrated using Marshall's (1971) wind tunnel data how the threshold friction velocity ratio Rt could be estimated as Rt(λ). Unfortunately, estimation of λ over large areas (regions etc.) is difficult and often approximated using classification of cover and vegetation type from satellite remote sensing and in the case of bare surfaces, using geometry. These approximations create surface discontinuities between classes and largely exclude heterogeneity due to mixtures of different surface types and canopies. Consequently, there is a need to reduce the uncertainty associated with the estimation of λ and develop a holistic approach common for all scales and surface mixtures of roughness types. When rough surfaces are exposed to the wind, wakes or areas of flow separation are created downwind of all obstacles. These sheltered areas reduce the area of exposed substrate and protect the erodible surface and some of the roughness elements from the wind (depending on their size and spacing). These sheltered areas have been conceptualised using shadow (Raupach, 1992) and shown to be proportional to shadow (Chappell et al., 2010). We made virtual reconstructions of Marshall's (1971) wind tunnel surfaces and applied a ray-tracer to estimate their at-nadir hemispherical ';black-sky' albedo (ωdir) and develop Rt(ωdir). In addition to that relationship being dependent on view zenith angle it is also dependent on waveband as evident by ω being influenced by soil moisture, soil colour etc. We use the ray-tracing simulations to normalise the data (Nω) and remove

  4. Bellholes: Ceiling Cavities Eroded By Bats in Caves of the Neotropical Climates

    NASA Astrophysics Data System (ADS)

    Miller, T.

    2014-12-01

    Puerto Rico suggest that a 30 cm diameter, 50 cm high bellhole could develop in fewer than 900 years. The numbers of bellholes and bellbasins suggest they may be an important post-formational erosional process in tropical caves, e.g. 4.8 linear cm of ceiling rock has been eroded just from the bellholes of only the first 600 m of a single cave in Puerto Rico.

  5. Depth-dependent erodibility: representing burnt soils as a two-layered cohesive/non-cohesive system

    NASA Astrophysics Data System (ADS)

    Nyman, P.; Sheridan, G. J.; Moody, J. A.; Smith, H. G.; Lane, P. N.

    2011-12-01

    Immediately after wildfire there is an abundant supply of non-cohesive ash, soil and gravel which is easily entrained by overland flow. Under these conditions the sediment flux on hillslopes can be assumed to be equal to the transport capacity of the flow. However, the supply of material is finite and at some point the hillslope could shift towards a system where entrainment is restricted by armouring and soil cohesion. In this study we test the notion that burnt hillslopes can be represented as a two-layered system of non-cohesive and cohesive soils. Using a combination of i) shear vane measurements, ii) confined hillslope flow experiments and iii) a laboratory flume, we demonstrate how erosion on burnt hillslopes primarily takes place in a distinct layer of non-cohesive soil with erosion properties that are very different to the underlying soil matrix. Shear vane measurements were taken at 5 soil depths at more than 50 points along transects in order to quantify the depth and spatial distribution of non-cohesive soil in two small (0.5 ha) and steep (30 deg) convergent basins (SE Australia) that were burnt at high severity. The measurements showed that the recently burnt hillslopes were mantled with non-cohesive soil to an average depth of 18mm and 20mm at the two sites which were situated in different geologic terrain but in similar eucalyptus dominated forests. In the hillslope flow experiments, the rapid entrainment of non-cohesive material resulted in very high sediment concentration (50-60% by volume) in the initial surge from the test area. During the flow experiments the sediment concentration decreased exponentially with time until the erosion rate reached a steady state reflecting the erodibility of the underlying cohesive soil. The formation of shallow rills and the presence of large clasts (>16cm) within the test area resulted in incomplete removal of the non-cohesive material at shear stress < 50 Ncm-2. At shear stress > 50 Ncm-2 all material was

  6. Composition and mean residence time of soil organic matter eroded from temperate, forested catchments: implications for erosion-induced carbon sequestration

    NASA Astrophysics Data System (ADS)

    Berhe, A. A.; McCorkle, E. P.; Stacy, E.; Hart, S. C.; Hunsaker, C. T.; Johnson, D. W.

    2014-12-01

    Topsoil and associated soil organic matter are continuously laterally distributed on the landscape by the process of soil erosion. The role of soil erosion on terrestrial carbon sequestration has been gaining a lot of attention over the last two decades. Soil erosion has been shown to lead to a sink of atmospheric carbon dioxide in soil if at least some of the eroded carbon is replaced by production of new photosynthate and/or some of the eroded carbon is stabilized in downslope depositional landform positions. However, until recently most of the work in this area has been focused on agricultural or grassland systems. Here, we present results from temperate forested catchments in the southern part of the Sierra Nevada Mountains. We found that most of the soil organic matter eroded from low-order catchments in the western slope of the Sierra Nevada Mountains is composed of forest floor material that has high concentrations of carbon. The steep slopes of these catchments also contribute to export of large proportion of the eroded forest floor material out of the catchments. Our radiocarbon analyses showed that the soil organic matter in the eroded material is composed of modern (post-1950) carbon with fraction modern values at or above 1. We also found that neither elevation, nor climate (across six years that we investigated) leads to significant changes in the composition and mean residence times of the eroded material, despite considerable differences in mean residence time of soil organic mater in soil profiles of the contributing hillslopes in the high vs. low elevation (low elevation: 1800 m, high elevation: 2300 m) catchments we studied. Our findings show that soil organic matter eroded from upland forested catchments is a lot more susceptible to decomposition, compared to organic matter eroded from agricultural or grassland systems likely leading to a less significant role of soil erosion on terrestrial carbon sequestration in forested catchments.

  7. Post-fire effects on hydrological and erodibility factors in a simulated burn and rainfall experiment

    NASA Astrophysics Data System (ADS)

    Keesstra, S. D.; Wittenberg, L.; Voogt, A.; Argaman, E.; Malkinson, D.

    2012-04-01

    Mediterranean forests are frequently subject to wildfires, inducing risks of runoff and loss of nutrient-rich topsoil. Post-fire causes for soil erosion are hard to separate. These mechanisms are spatially variable due to differences in vegetation density, litter composition, soil texture and structure, and fire intensity. However, the characteristics of soil and surface in the immediate post-fire period are of critical importance to the hydrological response and erosion susceptibility of the burned hillslope and catchment. The mentioned variation is still present in laboratory experiments, however a lot of it can be reduced by using homogeneous litter, uniform soil amounts and texture, controlled temperature and rain regimes and by replicating treatments. Moreover, fire and rain events can be simulated, enabling an imitation of a post-fire period. In this study we looked at post-fire observations for laboratory fire and rainfall (nozzle-type) simulation experiments to evaluate short-term effects of fire on soil hydrological and erodibility parameters by investigating (i) soil water repellency (WR) levels and distribution, (ii) surface cover features, and (iii) sat. hydraulic conductivity (Ksat), electrical conductivity and values of infiltration, runoff and erosion responses to simulated rain on control (bare and needle covered) and burned (with and without ash cover) samples. In the laboratory experiments we used a novel combination of techniques: (i) prepared trays of soil were manually burned; (ii) WR was measured before, in-between and after rainfall simulations; (iii) assessing of the degree and spatial variation for preferential surface flow; (iv) two rainfall simulations with drying period to simulate a part of a rainy season with cycles of wetting and drying (with its effects on soil hydrology, (re-)establishment hydrophobicity). The fire-induced surface WR in the lab, tested by grid-wise Water Drop Penetration tests, was moderate but decreased for all

  8. Highly erodible terrain in agriculture land against chipped pruned branches. Or how to stop the soil erosion with low investment

    NASA Astrophysics Data System (ADS)

    Cerdà, A.

    2009-04-01

    The session on "Soil erosion and sediment control with vegetation and bioengineering on severely eroded terrain" pays special attention to the severe soil erosion suffered on steep slopes and erodible parent materials and soils. Within the last 20 years, in the Mediterranean lands, the citrus orchards were reallocated on steep slopes due to the urban development and better climatic and management conditions of the new plantations. The lack of vegetation cover on the new slope plantations of citrus resulted in high erosion rates. Those non-sustainable soil losses were measured by means of rainfall simulation experiments, Gerlach collectors, geomorphological transect and topographical measurements. The October 2007 and October 2008 rainy periods resulted in sheet, rill and gully erosion. Some recently planted orchards (2005) had the first pruning season in 2008. The pruned chipped branches reduced the soil losses to 50 % of the expected, although the litter (pruned branches) covered 4.67 % of the soil. This is why a research was developed by means of simulated rainfall experiments to determine the vegetation cover (litter, mainly leaves) to protect the soil to reach a sustainable erosion rate. Rainfall simulation experiments at 43 mm h-1 where performed on 1 m2 plots covered with 0, 3, 7, 15, 30, 45, 60, 80 and 100 % litter cover (pruned chipped branches) to determine the sustainable litter cover to avoid the soil losses. The results show that more that 45 % litter cover almost reduces the soil losses to negligible rates. The results confirm that 4 % of vegetation cover reduces the soil losses to 50 %. Key words: Agriculture land, erodible terrain, land management, citrus, erosion, Spain, Valencia, herbicides. Acknowledgements, We thanks the financial support of the Ministerio de Ciencia e Innovación by means of the project CGL2008-02879/BTE, "PERDIDA DE SUELO EN NUEVAS EXPLOTACIONES CITRICOLAS EN PENDIENTE. ESTRATEGIAS PARA EL CONTROL DE LA EROSION HIDRICA"

  9. [Characteristics of Soil Respiration along Eroded Sloping Land with Different SOC Background on the Hilly Loess Plateau].

    PubMed

    Chen, Gai; Xu, Ming-xiang; Zhang, Ya-feng; Wang, Chao-hua; Fan, Hui-min; Wang, Shan-shan

    2015-09-01

    This study aimed to characterize soil respiration along eroded sloping land at erosion and deposition area under different soil organic carbon(SOC) levels, and linked the relationship between soil respiration and soil temperature, soil moisture, SOC and slope position. Experiments were carried out in the plots of S type slopes include five different soil organic carbon levels in the Loess Hilly Region. The S type slopes were divided into control area at the top of the slope, erosion area at the middle of the slope and deposition area at the toe of the slope. We found that soil temperature had a greater impact on soil respiration in the deposition area, whereas soil moisture had a greater impact on soil respiration in the erosion area compared among control area, erosion area and deposition area. In addition, SOC was the most important factor affecting soil respiration, which can explain soil respiration variation 54. 72%, followed by soil moisture, slope position and soil temperature, which explain soil respiration variation 18. 86% , 16. 13% and 10. 29%, respectively. Soil respiration response to erosion showed obvious on-site and off-site effects along the eroded sloping land. Soil respiration in the erosion area was reduced by 21. 14% compared with control area, and soil respiration in the deposition area was increased by 21. 93% compared with control area. Erosion effect on source and sink of carbon emission was correlated with SOC content of the eroded sloping land. When SOC content was higher than 6. 82 g.kg-1, the slope. erosion tended to be a carbon sequestration process, and when SOC content was lower than 3.03 g.kg-1, the slope erosion tended to be a process of the carbon emission source. The model could reflect the relationship between soil respiration and independent variables of soil organic carbon content, soil temperature and moisture.

  10. On-board Optical Spectrometry for Detection of Mixture Ratio and Eroded Materials in Rocket Engine Exhaust Plume

    NASA Technical Reports Server (NTRS)

    Barkhoudarian, Sarkis; Kittinger, Scott

    2006-01-01

    Optical spectrometry can provide means to characterize rocket engine exhaust plume impurities due to eroded materials, as well as combustion mixture ratio without any interference with plume. Fiberoptic probes and cables were designed, fabricated and installed on Space Shuttle Main Engines (SSME), allowing monitoring of the plume spectra in real time with a Commercial of the Shelf (COTS) fiberoptic spectrometer, located in a test-stand control room. The probes and the cables survived the harsh engine environments for numerous hot-fire tests. When the plume was seeded with a nickel alloy powder, the spectrometer was able to successfully detect all the metallic and OH radical spectra from 300 to 800 nanometers.

  11. Long distance observations with the ChemCam Remote Micro-Imager: Eroded Mount Sharp deposits on Gale Crater floor?

    NASA Astrophysics Data System (ADS)

    Newsom, Horton; Gasnault, Olivier; Le Mouélic, Stéphane; Mangold, Nicolas; Le Deit, Laetitia; Wiens, Roger; Anderson, Ryan; Herkenhoff, Ken; Johnson, Jeffrey R.; Bridges, Nathan; Grotzinger, John P.; Gupta, Sanjeev; Jacob, Samantha; MSL Science Team

    2016-10-01

    Curiosity's ChemCam includes a Remote Micro-Imager (RMI) to provide context for the laser pits, to obtain long-range images, and for passive reflectance spectra (400-840 nm). Use of the RMI has been enhanced by a new autofocus algorithm using onboard analysis of RMI images. The RMI has the finest pixel scale on the rover with 19.6 μrad/pixel (1024x1024 grayscale), compared to Mastcam M100 color images (74 μrad/pixel). The pixel scale for RMI images is ~2 cm at 1 km, and ~26 cm at 12 km, beyond which HiRISE orbital resolution (25 cm/pixel) is better. Note: useful resolution of geological features requires 3-5 pixels. A major question for Gale Crater (age 3.6 BY), is whether the presently truncated deposits on Mt. Sharp originally extended across the crater floor, prior to the deposition of Peace Vallis and other fans at 3.2 BY? HiRISE imagery shows early, partly eroded deposits in the vicinity of the Peace Vallis fan, but the materials could have been impact related. Long distance RMI images of the deposits, however, confirm the presence of eroded buttes with at least 8-10 horizontal layers (0.8–1.6 m thick) in one example, consistent with a sedimentary origin. The layered buttes rise as much as 12 meters above the surrounding deposits. The later deposits embay the lower portions of the buttes and are probably a phase of the later Peace Vallis fan. The RMI images show the presence of blocks in this fan unit of about 50-80 cm, consistent with an enhanced retention of craters that has been noted for this unit. Another RMI observation just above the Peace Vallis channel shows an eroded bench or series of layered hills at the same level, that could also indicate early sediment deposits prior to Peace Vallis fan. Conclusions - The RMI images (and HiRISE images of other crater floor deposits) suggest at least some deposits possibly related to Mt. Sharp were present on the crater floor near the Peace Vallis fan and now are highly eroded, but their original thickness is

  12. Is the Bangweulu Basin in Zambia the Eroded Remnant of a Large, Multiring Impact Crater?

    NASA Astrophysics Data System (ADS)

    Master, S.

    1993-07-01

    , surrounded by an arcuate high south of the Luongo Fold Belt [7,8]. There are few heat flow measurements in Zambia [9], but there is no indication that the Bangweulu Basin has abnormally high heat flow, which is present in the Luangwaand Upper Zambezi rifts, as evidenced by numerous hot springs and historical geysers [10]. Satellite imagery of Central Africa clearly shows a roughly circular outline of the Bangweulu Basin, including the lakes and swamps, surrounded by a concentric ring of uplifts. The concentric islands in Lake Bangweulu are reminiscent of the multiple concentric rings around impact basins in other planetary bodies, e.g., Valhalla and Asgard structures on the jovian moon of Callisto. Lunar craters Eratosthenes, Aristarchus, and others also have similar terraced morphologies with concentric rings. Based on the above geomorphological and geophysical features, it is postulated that the Bangweulu Basin represents the eroded remnant of a large multiring impact structure that postdates the Katangan Supergroup. Any possible connection between the Bangweulu structure and the Lukanga swamp (a postulated astrobleme in central Zambia [11]) is unknown at this stage. Ground search for macro- and microscopic shock features in the Bangweulu Basin is planned for 1994. References: [1] Debenham F. (1947) Geog. Rev., 37, 351-368. [2] Thieme J. G. and Johnson R. L. (1976) The 1:1,000,000 Scale Geological Map of the Republic of Zambia, Geol. Surv. Zambia. [3] Andersen L. S. and Unrug R. (1984) Precambrian Res., 25, 187-212. [4] Bram K. (1972). Bull. Seis. Soc. Am., 62, 1211-1216. [5] Fairhead J. D. and Henderson N. B. (1977) Tectonophysics, 41, 19-26. [6] Saviaro K. (1979) Bull. Geol. Surv. Botswana, 22, 159-181. [7] Mazac O. (1974) Tech. Rept. Geol. Surv. Zambia, 76, 40 pp. [8] Cowan I. M. and Pollack H. N. (1977) Nature, 266, 615-617. [9] Chapman D. S. and Pollack H. N. (1975) Nature, 256, 28-30. [10] Legg C. A. (1974) Econ. Rept. Geol. Surv. Zambia, 50, 60 pp. [11] Vrana S

  13. Contaminated soil phytoremediation by Cyperus laxus Lam. cytochrome p450 EROD-activity induced by hydrocarbons in roots.

    PubMed

    López-Martínez, S; Gallegos-Martínez, M E; Pérez-Flores, L J; Gutiérrez-Rojas, M

    2008-01-01

    Laboratory and greenhouse experiments with Cyperus laxus Lam were conducted to determine the rate and extent of phytoremediation and the effect of hydrocarbons on the cytochrome P450 EROD (7-ethoxyresorufin-O-deethylase) enzymatic activity in roots. Plants were cultivated on hydrocarbon-contaminated soil (HCS) and spiked perlite. Phytoremediation was evaluated using 6.5 kg HCS (173 +/- 15 mg total petroleum hydrocarbons [TPH] g(-1) of dry soil) pots at different moisture contents; the average removal rate was 3.46-0.25 mg TPH g(-1) dry soil month(-1) and 48% was removed when moisture was kept at 60%. The aromatic hydrocarbon fraction was the mostly removed, 60%; aliphatic, 51%; and polar 24% after 24-month experiments. In unplanted pots, TPH concentration did not exhibit significant differences with respect to the initial concentration. We confirmed that the presence of hydrocarbons induced ERODactivity up to 6.5-fold. Moreover, short-term experiments (up to 13 d) with spiked perlite demonstrated that two EROD activities in roots contributed to the total detected; 60% was found in the cytosolic and 40% in the microsomal fraction. To our knowledge, this is the first work that tries to build links between the hydrocarbon-inducible character of ERODactivity in roots and the phytoremediation ability of C. laxus in highly contaminated soils. PMID:19260214

  14. Coupled dynamics of interfacial waves and bed forms in fluid muds over erodible seabeds in oscillatory flows

    NASA Astrophysics Data System (ADS)

    Trowbridge, J. H.; Traykovski, P.

    2015-08-01

    Recent field investigations of the damping of ocean surface waves over fluid muds have revealed waves on the interface between the thin layer of fluid mud and the overlying much thicker column of clear water, accompanied by bed forms on the erodible seabed beneath the fluid mud. The frequencies and wavelengths of the observed interfacial waves are qualitatively consistent with the linear dispersion relationship for long interfacial waves, but the forcing mechanism is not known. To understand the forcing, a linear model is proposed, based on the layer-averaged hydrostatic equations for the fluid mud, together with the Meyer-Peter-Mueller equation for the sediment transport within the underlying seabed, both subject to oscillatory forcing by the surface waves. If the underlying seabed is nonerodible and flat, the model indicates parametric instability to interfacial waves, but the threshold for instability is not met by the observations. If the underlying seabed is erodible, the model indicates that perturbations to the seabed elevation in the presence of the oscillatory forcing create interfacial waves, which in turn produce stresses within the fluid mud that force a net transport of sediment within the seabed toward the bed form crests, thus causing growth of both bed forms and interfacial waves. The frequencies, wavelengths, and growth rates are in qualitative agreement with the observations. A competition between mixing created by the interfacial waves and gravitational settling might control the thickness, density, and viscosity of the fluid muds during periods of strong forcing.

  15. Short-pulse Er:YAG laser increases bond strength of composite resin to sound and eroded dentin

    NASA Astrophysics Data System (ADS)

    Cersosimo, Maria Cecília Pereira; Matos, Adriana Bona; Couto, Roberta Souza D.'Almeida; Marques, Márcia Martins; de Freitas, Patricia Moreira

    2016-04-01

    This study evaluated the influence of the irradiation with a short-pulse Er:YAG laser on the adhesion of composite resin to sound and eroded dentin (SD and ED). Forty-six samples of occlusal dentine, obtained from human molars, had half of their surface protected, while the other half was submitted to erosive cycles. Afterward, 23 samples were irradiated with Er:YAG laser, resulting in four experimental groups: SD, sound irradiated dentine (SID-Er:YAG, 50 μs, 2 Hz, 80 mJ, and 12.6 J/cm2), ED, and eroded irradiated dentin (EID-erosion + Er:YAG laser). A self-etching adhesive system was used, and then cylinders of composite resin were prepared. A microshear bond strength test was performed after 24 h storage (n=20). The morphology of SD and ED, with or without Er:YAG laser irradiation, was evaluated under scanning electron microscopy (n=3). Bond strength values (MPa) were subjected to analysis of variance followed by Tukey's test. Statistically significant differences were found among the experimental groups: SD (9.76±3.39 B), SID (12.77±5.09 A), ED (5.12±1.72 D), and EID (7.62±3.39 C). Even though erosion reduces the adhesion to dentin, the surface irradiation with a short-pulse Er:YAG laser increases adhesion to both ED and SD.

  16. Short-pulse Er:YAG laser increases bond strength of composite resin to sound and eroded dentin

    NASA Astrophysics Data System (ADS)

    Cersosimo, Maria Cecília Pereira; Matos, Adriana Bona; Couto, Roberta Souza D.'Almeida; Marques, Márcia Martins; de Freitas, Patricia Moreira

    2016-04-01

    This study evaluated the influence of the irradiation with a short-pulse Er:YAG laser on the adhesion of composite resin to sound and eroded dentin (SD and ED). Forty-six samples of occlusal dentine, obtained from human molars, had half of their surface protected, while the other half was submitted to erosive cycles. Afterward, 23 samples were irradiated with Er:YAG laser, resulting in four experimental groups: SD, sound irradiated dentine (SID-Er:YAG, 50 μs, 2 Hz, 80 mJ, and 12.6 J/cm2), ED, and eroded irradiated dentin (EID-erosion + Er:YAG laser). A self-etching adhesive system was used, and then cylinders of composite resin were prepared. A microshear bond strength test was performed after 24 h storage (n=20). The morphology of SD and ED, with or without Er:YAG laser irradiation, was evaluated under scanning electron microscopy (n=3). Bond strength values (MPa) were subjected to analysis of variance followed by Tukey's test. Statistically significant differences were found among the experimental groups: SD (9.76±3.39 B), SID (12.77±5.09 A), ED (5.12±1.72 D), and EID (7.62±3.39 C). Even though erosion reduces the adhesion to dentin, the surface irradiation with a short-pulse Er:YAG laser increases adhesion to both ED and SD.

  17. Impact of fencing on the recovery of the ground flora on heavily eroded slopes of a deciduous forest.

    PubMed

    Godefroid, Sandrine; Massant, Wim; Weyembergh, Gisele; Koedam, Nico

    2003-07-01

    This paper seeks to outline early stages in the recovery of forest ground flora on eroded slopes impacted by recreation activities and to suggest how these data might be applied in the formulation of management policies for forest recreation areas. Based on a fencing experiment in the Sonian Forest near Brussels, we investigated whether, over a 6-year period, the vegetation was able to recover after having been destroyed by recreation use. Short-term trends in overall species composition were already observable during this 6-year study. Species recovery on eroded hills was related to slope, aspect, and soil type. During the considered time scale, the proportion of hemicryptophytes and the number of ancient forest species increased significantly. A downward trend was detected for Ellenberg's nitrogen and temperature indexes and for the proportion of therophytes and pioneer plants of disturbed places. Changes in species' frequencies suggest six recovery strategies: early, late, expanding, disappearing, transient, and fluctuating species. Aside from seedling reproduction from overstory influences, Luzula sylvatica appeared to be the most resilient of the species identified in the study since this species has the highest global frequency in our sampling plots and has increased its cover during the study period. Study results indicate that (1) protection from recreation has initiated the recovery of species in the herb layer, but (2) it may take a long time before vegetation previously present in the ground flora may recover in both density and species composition.

  18. Effect of CPP-ACP on the remineralization of acid-eroded human tooth enamel: nanomechanical properties and microtribological behaviour study

    NASA Astrophysics Data System (ADS)

    Zheng, L.; Zheng, J.; Zhang, Y. F.; Qian, L. M.; Zhou, Z. R.

    2013-10-01

    Casein phosphopeptide-stabilized amorphous calcium phosphate (CPP-ACP) has been used to enhance tooth remineralization in the dental clinic. But the contribution of CPP-ACP to the remineralization of acid-eroded human tooth enamel is of widespread controversy. To confirm the application potential of CPP-ACP in the remineralization repair of tooth erosion caused by acid-attack, the effect of remineralization in vitro in 2% w/v CPP-ACP solution on the acid-eroded human tooth enamel was investigated in this study. The repair of surface morphology and the improvement of nanomechanical and microtribological properties were characterized with laser confocal scanning microscope, scanning electron microscope, nanoindentation tester and nanoscratch tester. Results showed that a layer of uneven mineral deposits, which were mainly amorphous calcium phosphate (ACP) in all probability, was observed on the acid-eroded enamel surface after remineralization. Compared with the acid-eroded enamel surface, the nanoindentation hardness and Young's modulus of the remineralized enamel surface obviously increased. Both the friction coefficient and wear volume of the acid-eroded enamel surface decreased after remineralization. However, both the nanomechanical and the anti-wear properties of the remineralized enamel surface were still inferior to those of original enamel surface. In summary, tooth damage caused by acid erosion could be repaired by remineralization in CPP-ACP solution, but the repair effect, especially on the nanomechanical and anti-wear properties of the acid-eroded enamel, was limited. These results would contribute to a further exploration of the remineralization potential of CPP-ACP and a better understanding of the remineralization repair mechanism for acid-eroded human tooth enamel.

  19. Some polybrominated diphenyl ether (PBDE) flame retardants with wide environmental distribution inhibit TCDD-induced EROD activity in primary cultured carp (Cyprinus carpio) hepatocytes.

    PubMed

    Kuiper, R V; Bergman, A; Vos, J G; van den Berg, M

    2004-06-10

    Ethoxyresorufin-O-deethylase (EROD) activity, a catalytic function of the cytochrome P450 1A (CYP1A) microsomal oxygenase subfamily, is a popular biomarker for exposure to xenobiotics, polyhalogenated aromatic hydrocarbons (PHAHs) in particular. It has found wide use in aquatic pollution assessment both in vivo and in vitro. In such studies, subjects are often exposed to complex mixtures where various constituents can interfere with EROD-activity, possibly resulting in inadequate estimation of toxic hazard or biological response. The present study investigates the effects of polybrominated diphenyl ethers (PBDEs), a relatively new and increasingly detected group of environmental contaminants, on the validity of EROD activity as exposure marker in carp (Cyprinus carpio) hepatocytes. Freshly isolated hepatocytes of a genetically uniform strain of male carp were co-exposed to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) at concentrations of 0, 1, 3, 10, 30, and 100 pM, and one of the highly purified PBDE/PCB congeners (at concentrations of 0, 0.25, and 2.5 microM) or cleaned-up and untreated DE-71 samples (0, 0.1, and 1 microM). PBDEs were selected from the 209 possible congeners based on their relative abundance in environmental samples: BDE-47, BDE-99, BDE-100, and BDE-153. A tentative metabolite of BDE-47, 6OH-BDE-47, was also included. In addition, a commercial pentabrominated dipenylether mixture (DE-71) was tested for interference with EROD activity both with and without clean-up by carbon fractionating which removed possible planar contaminants. Polychlorinated biphenyl (PCB)-153, a reported inhibitor of EROD activity in flounder, was included for comparison. Cells were cultured for a total period of 8 days; exposure started at day 3 after cell isolation. After 5 days of exposure, cell pellets were frozen before EROD activity was determined. Upon exposure to TCDD, the cells responded with increased EROD activity as expected. Significant reduction of TCDD

  20. Aero-acoustic Properties of Eroded Airfoils of Compressor Blades for Use in Non-invasive Diagnostics

    NASA Astrophysics Data System (ADS)

    Drãgan, Valeriu; Grad, Danuţa

    2013-09-01

    The current techniques for investigating the erosion of turbo machineries rely on visual inspections trough boroscopy. However this implies shutting down the power plant in order to make the assessment which leads to operational costs and difficulties. This paper aims to provide a method for monitoring the erosion state of a bladed power plant operated in dusty environments such as the desert by measuring the changes in its acoustic spectrum. The method used for this study is numerical and the findings suggest that there are significant modifications to both the flow field and the acoustic parameters as the blade gets progressively eroded. This paves the way for the development of non-invasive permanent real time diagnostics for turbine engines and power plants.

  1. Distribution of velocity and turbulent characteristics in coarse-sediment laden flows above erodible plane bed in open channel

    NASA Astrophysics Data System (ADS)

    Zrostlík, Štěpán; Bareš, Vojtěch; Krupička, Jan; Picek, Tomáš; Matoušek, Václav

    2016-03-01

    Extreme conditions as flash floods in steep mobile-bed streams induce flows which carry a huge amount of sediment. Typically, the flow with the intense transport of sediment is stratified with a layered structure above an erodible plane bed. The paper deals with local flow characteristics in the layered structure of the two-phase flow composed of water and sediment. We present experimental data and results for two different fractions of plastic particles obtained using two acoustic Doppler methods and a Prandtl probe. The results contain vertical profiles of longitudinal velocity component and local turbulent characteristics of the flow as the Reynolds stress and turbulent intensity. The effect of the layered character of the flow on the flow characteristics is discussed. Special attention is paid to the distribution of Reynolds stress in the sediment-rich transport layer above the bed and to the evaluation of ability of carrier turbulent eddies to support sediment grains in and above the transport layer.

  2. Sudden clearing of estuarine waters upon crossing the threshold from transport to supply regulation of sediment transport as an erodible sediment pool is depleted: San Francisco Bay, 1999

    USGS Publications Warehouse

    Schoellhamer, David H.

    2011-01-01

    The quantity of suspended sediment in an estuary is regulated either by transport, where energy or time needed to suspend sediment is limiting, or by supply, where the quantity of erodible sediment is limiting. This paper presents a hypothesis that suspended-sediment concentration (SSC) in estuaries can suddenly decrease when the threshold from transport to supply regulation is crossed as an erodible sediment pool is depleted. This study was motivated by a statistically significant 36% step decrease in SSC in San Francisco Bay from water years 1991–1998 to 1999–2007. A quantitative conceptual model of an estuary with an erodible sediment pool and transport or supply regulation of sediment transport is developed. Model results confirm that, if the regulation threshold was crossed in 1999, SSC would decrease rapidly after water year 1999 as observed. Estuaries with a similar history of a depositional sediment pulse followed by erosion may experience sudden clearing.

  3. Effect of Toothpastes with Different Abrasives on Eroded Human Enamel: An in situ/ex vivo Study

    PubMed Central

    Ferreira, Meire Coelho; Ramos-Jorge, Maria Letícia; Delbem, Alberto Carlos Botazzo; Vieirac, Ricardo de Sousa

    2013-01-01

    The aim of the present study was to investigate the abrasive effect of CaCO3 and SiO2-based fluoride-free experimental toothpastes on eroded human permanent dental enamel and evaluate the effectiveness of waiting periods between acid exposure and tooth brushing. Twelve volunteers wore palatal appliances containing human enamel blocks for two periods of five days each. The appliances were immersed in a soft drink for five minutes four times a day (9:00 am, 11:00 am, 2:00 pm and 4:00 pm). On two occasions, two blocks were not submitted to additional treatment; two blocks were brushed (30 s) either with a CaCO3 or SiO2 toothpaste immediately after erosion and two blocks were brushed 1 h after erosion. Thus, the sample was divided into six groups: erosion alone (CaCO3 and SiO2 control); brushing with fluoride-free toothpaste (CaCO3 immediate and 1 h after erosion; SiO2 immediate and 1 h after erosion). Significant differences in wear depth were found between the enamel blocks in the CaCO3 immediate and 1 h after erosion groups and the blocks in the CaCO3 control group (p=0.001; p=0.022). No significant differences were found regarding the change in roughness and wear depth between blocks submitted to immediate abrasion and 1 h after erosion (CaCO3 and SiO2). The data revealed that surface roughness and wear depth is increased when erosion is combined with dental abrasion, regardless of the abrasive used. Waiting for 1 h to brush the eroded blocks offered no protective effect. PMID:24198851

  4. One-Step Posterior and Anterior Combined Approach for L5 Retroperitoneal Schwannoma Eroding a Lumbar Vertebra

    PubMed Central

    Picotti, Veronica; Raco, Antonino

    2016-01-01

    We report the case of a large lumbar schwannoma eroding the vertebra and originating from spinal canal with invasion of the retroperitoneal space. We also review all the cases in literature reporting lumbar schwannomas eroding the vertebral bodies and invading the retroperitoneal space focusing on the surgical strategies to manage them. Spinal CT-scan revealed a 44 mm × 55 mm inhomogeneous soft-tissue mass arising from the right L5-S1 neural foramen and its most anterior portion had a clear colliquative aspect. Magnetic resonance image showed a neoplastic lesion with homogeneous low signal in T1WI, heterogeneous signal in T2WI, and strong enhancement in postgadolinium examination. It developed as well in the retroperitoneal space, posteriorly to the iliac vein, up to the psoas muscle with wide erosion of the omolateral conjugate foramen. We performed a one-step combined approach together with the vascular surgeon because the lesion was too huge to allow a complete resection via a posterior approach and furthermore its tight relationship with the psoas muscle and the iliac vessels in the retroperitoneal space should be more safely managed via a retroperitoneal approach. We strongly suggest a 1-step surgery first approaching the dumbbell and the intraspinal schwannomas posteriorly achieving the decompression of the spinal canal and the cleavage of the tumor cutting the root of origin and the vascular supply and valuating the stability of the spine for potential artrodesis procedure. The patient must be then operated on via a retroperitoneal approach achieving the complete en bloc resection of the tumor. PMID:27766176

  5. Evaluation of liver histopathology and EROD activity in St. Lawrence lake sturgeon (Acipenser fulvescens) in comparison with a reference population

    SciTech Connect

    Rousseaux, C.G. ||; Branchaud, A.; Spear, P.A.

    1995-05-01

    In an attempt to evaluate the effects of contaminants on the lake sturgeon Acipenser fulvescens, fish were netted from two sites: Riviere des Prairies, confluent with the St. Lawrence River near Montreal, and a reference site on the upper reaches of the Ottawa River in the La Verendrye Park. Livers of fish collected from the Riviere des Prairies were difficult to homogenize, and they left behind strands of what appeared to be connective tissue. Suspecting hepatic fibrosis, the authors decided to evaluate the livers for histopathologic changes. Nineteen adult lake sturgeon (eleven male and eight female) were examined. Following fixation, routine processing, sectioning, and staining with hematoxylin and eosin, microscopic evaluation revealed the following: Sections taken from livers of fish from the Riviere des Prairies site showed excessive fat accumulation and often severe chronic-active cholangiohepatitis. Bile duct proliferation (p < 0.0001), periportal fibrosis (p < 0.0001), inflammation (p < 0.001), and fat accumulation (p < 0.05) were more pronounced in the fish from the Riviere des Prairies site. Melano-macrophage centers appeared to be both paler and gave the appearance of fewer numbers (p < 0.01). Livers from lake sturgeon taken from the reference site had a more normal appearance. The EROD levels were also significantly induced in these fish (reference 3.39 {+-} 0.57; Riviere des Prairies site 8.21 {+-} 0.87 pmol/mg protein/min; p < 0.0005). The EROD levels positively correlated with bile duct proliferation (r{sup 2} = 0.44; p = 0.001) and periportal fibrosis (r{sup 2} = 0.41; p = 0.002). Despite the statistical associations above, the authors cannot categorically state that contaminants are the sole cause of the lesions seen.

  6. Finding Eroding Areas and Patterns with GIS, Caesium-137 Tracers, and Community Knowledge in the Ethiopian Highlands

    NASA Astrophysics Data System (ADS)

    Guzman, C. D.; Tilahun, S. A.; Zegeye, A. D.; Yitaferu, B.; Steenhuis, T. S.

    2012-12-01

    While soil erosion has been reducing agricultural productivity in developing countries for decades, its effects and seriousness are gaining more attention, especially with respect to shortening the life of reservoirs for hydroelectric power generation. This has urged policy makers to develop comprehensive sustainable strategies for environmental conservation. To develop such strategies, however, assumptions made within the different areas of knowledge that concurrently study soil conservation must be challenged and verified. A central aim of this study on soil erosion and conservation is to bridge between social science and engineering disciplines by comparing and contrasting estimates and identification of eroding areas and patterns. In Debre Mewi, Ethiopia, we examine spatial and temporal variations in erosion from an agricultural watershed and its subsequent soil nutrient changes using GIS-based erosion prediction tools, the soil-adsorbed radionuclide caesium-137 as a sediment tracer, and community knowledge. We plan to reconcile differences between theoretical formulations, actual measurements, and community perceptions and insight. Sixteen sites are monitored in this small watershed 50 km south of Lake Tana, with characteristic semi-monsoonal rains, during the long (kremt) rainy season for topsoil depth change, water table height, soil nutrients (N, P, K, Mg, Ca), and ceasium-137 inventory. While focus group discussions and transect walks with the community describe spring flow paths, saturated areas, degraded areas and active gullies as primary zones of erosion, GIS-based prediction tools treat steep slopes and cropped land as areas vulnerable to erosion. Cs-137 tracers map the upland mildly sloping areas to be eroding at a greater average rate than any of the mid-slope or toe-slope areas. Finally, from these comparisons, we draw information helpful in understanding why and how sediment concentration and erosion decreases and what impact we can expect to see

  7. Can bioengineering structures made of willow cuttings trap sediment in eroded marly gullies in a Mediterranean mountainous climate?

    NASA Astrophysics Data System (ADS)

    Rey, Freddy; Burylo, Mélanie

    2014-01-01

    In the Southern French Alps, high sediment yields from marly catchments cause socio-economic and ecological problems downstream. Bioengineering structures made of willow cuttings could be used for efficient and sustainable sediment trapping in eroded gullies in order to decrease sediment yield at their outlets. However, little has been done to quantitatively assess the efficiency of such structures for trapping sediment or to improve their performance. The objectives of this study were to analyze the ability of bioengineering structures to enhance vegetation development and sediment trapping in marly gullies in the Southern French Alps, under a mountainous and Mediterranean climate. For five years after the restoration operations, we monitored 101 bioengineering structures using willow (Salix) cuttings, including 55 brush layers on wooden sills (BL) and 46 brush layers with brush mats on wooden sills (BLM), 1.2 m wide and 2 m long, installed on the floors of eight experimental marly gullies. The results showed that the ultimate survival of willow cuttings can be assessed after three years. Gully size and aspect appeared to be the most important factors influencing resprouting rates. By avoiding south-oriented gullies and those smaller than 1000 m2, 75% survival rates per structure may be achieved. The results also showed that BL trapped 0.18 m3 yr- 1 of sediment per structure on average and BLM 0.21 m3 yr- 1, but potential maximum values may reach 0.28 and 0.40 m3 yr- 1 over one year on BL and BLM, respectively. Therefore, bioengineering structures made of willow cuttings can be used to trap significant quantities of sediment from the first year onwards and efficiently restore eroded marly gullies under a Mediterranean mountainous climate. It also provides design criteria to guide future restoration actions and future investigations in the Southern French Alps.

  8. Relevance of macrozoobenthic grazers to understand the dynamic behaviour of sediment erodibility and microphytobenthos resuspension in sunny summer conditions

    NASA Astrophysics Data System (ADS)

    Orvain, Francis; Guizien, Katell; Lefebvre, Sébastien; Bréret, Martine; Dupuy, Christine

    2014-09-01

    The quantification of overall microphytobenthos productivity should include the export of biomass from the intertidal zone during high tides, which implies refined estimates and concepts of erosion parameters. For the first time, the export of microphytobenthic cells was assessed over an intertidal mudflat in the Marennes-Oléron Bay, France, during a complete spring/neap tide modulation. In the summer of 2008, resuspension rates of chl-a exported only reached 2.5% of the standing stock of benthic diatoms on each day. Sedimentary factors failed to explain any variation regarding bed and microphytobenthos erodibility. During the early fluff layer erosion phase, there were negative effects of grazing activities exerted by motile infauna (Peringia ulvae) on erosion fluxes of chl-a, while there was a related positive correlation with pheopigment proportion. The erosion process plays an important role in this vegetal-herbivore interaction by reinforcing the decline of the microphytobenthic biomass and provoking a catastrophic shift to mass erosion after a sequence of several days of co-occurring intense grazing by snails and chl-a decline. During mass erosion, the biofilm decline explained the variations of sediment erodibility, with a marked negative correlation between bound extracellular polymeric substance (EPS) proteins and critical threshold for bed erosion, in contrast with the commonly observed positive influence of EPS secretion on bed resistance. The complex nature of the effects of EPS by microphytobenthos must be further investigated to unravel their complex role in bioengineering sediments. The increase of protein proportion in EPS could provide specific properties related to hydrophilic features. Nevertheless, the level of grazing pressure by P. ulvae should be so intense that the top-down control must explain this original finding, since there was a positive correlation of proteins in EPS and snail density that could be related to mucus secretion (as a

  9. The effects of Herba Andrographitis hedgerows on soil erodibility and fractal features on sloping cropland in the Three Gorges Reservoir Area.

    PubMed

    Chen, Jingjing; He, Binghui; Wang, Xiaoyan; Ma, Yun; Xi, Weimin

    2013-10-01

    To evaluate if hedgerows could improve the soil physicochemical properties and enhance the soil anti-scouring and anti-shearing capabilities, the effects of Herba Andrographitis hedgerows on soil erodibility and fractal features on sloping cropland in the Three Gorges Reservoir Area were investigated. Results showed that: (1) the clay particle accumulation around the hedgerows was significantly affected by the hedgerows; (2) the fractal dimension of soil particles was positively correlated with both silt and clay contents and had a negative linear correlation with sand content; (3) fine-grained content significantly influenced fractal dimension of the soil particles; (4) soil erodibility K was significantly and positively correlated with the sand content (correlation coefficient r=0.870), but significantly and negatively correlated with the silt content (r=-0.538), clay content (r=-0.739), organic carbon content (r=-0.603), the aggregation degree (r=-0.486), and soil fractal dimension (r=-0.538); and (5) the contents of organic matter and clay particles in the soil were found to be the effective indicators for soil erodibility at the Three Gorges Reservoir Area. The hedgerows may improve soil fractal features and decrease soil erodibility. The effective distance between hedgerows on a slope of 10° was less than 6 m. PMID:23608982

  10. A field evaluation of cytochrome P4501A as a biomarker of contaminant exposure in three species of flatfish

    SciTech Connect

    Collier, T.K.; Anulacion, B.F.; Stein, J.E.; Varanasi, U. ); Goksoeyr, A. . Lab. of Marine Molecular Biology)

    1995-01-01

    A study was conducted over the course of a year to determine the induction of hepatic cytochrome P4501A (CYP1A) in three species of benthic fish collected from a contaminated site compared to fish sampled from a less-contaminated site. Juvenile fish were used to minimize effects of reproductive status and migration. CYP1A was determined by two catalytic assays [aryl hydrocarbon hydroxylase (AHH) and ethoxyresorufin O-deethylase (EROD)] and by an immunoassay (ELISA) utilizing polyclonal antibodies raised against purified CYP1A from cod. AHH activities were measured by a standard method (AHH[sub std]) and by two variations of the standard method. All three primary CYP1A measures (AHH[sub std], EROD, and ELISA) showed consistent between-site differences, indicating that induction of CYP1A can be a reliable biomarker of contaminant exposure in fish if appropriate biological variables are controlled for in field studies. Multiple ANOVA demonstrated that the AHH[sub std] and ELISA data showed less variability due to species or temporal differences, and less unexplained variability, compared to the data from the EROD assay or either variation of the AHH assay. For all measures, variability associated with site differences far outweighed species or temporal variability. Immunoassay, while less sensitive than the AHH[sub std] assay, is nonetheless recommended to be used in conjunction with catalytic assays because of the potential for samples to lose catalytic activity if not handled properly. The current results suggest that the lower noncontaminant-related variability of AHH[sub std] makes this CYP1A measure potentially more useful for monitoring programs in which analysis of trends is a primary goal.

  11. The effects of the mineral phase on C stabilization mechanisms and the microbial community along an eroding slope transect

    NASA Astrophysics Data System (ADS)

    Doetterl, S.; Opfergelt, S.; Cornelis, J.; Boeckx, P. F.; van oost, K.; Six, J.

    2013-12-01

    An increasing number of studies show the importance of including soil redistribution processes in understanding carbon (C) dynamics in eroding landscapes. The quality and quantity of soil organic carbon in sloping cropland differs with topographic position. These differences are commonly more visible in the subsoil, while the size and composition of topsoil C pools are similar along the hillslope. The type (plant- or microbial-derived) and quality (level of degradation) of C found in a specific soil fraction depends on the interplay between the temporal dynamic of the specific mechanism and it's strength to protect C from decomposition. Here, we present an analysis that aims to clarify the bio/geo-chemical and mineralogical components involved in stabilizing C at various depths and slope positions and how they affect the microbial community and the degradation of C. For this we analyzed soil samples from different soil depths along a slope transect applying (i) a sequential extraction of the reactive soil phase using pyrophosphate, oxalate and dithionite-citrate-bicarbonate, (ii) a semi-quantitative and qualitative analysis of the clay mineralogy, (iii) an analysis of the microbial community using amino sugars and (iv) an analysis of the level of degradation of C in different soil fractions focusing on the soil Lignin signature. The results show that the pattern of minerals and their relative importance in stabilizing C varies greatly along the transect. In the investigated soils, pyrophosphate extractable Manganese, and not Iron or Aluminum as often observed, is strongly correlated to C in the bulk soil and in the non-aggregated silt and clay fractions. This suggests a certain role of Manganese for C stabilization where physical protection is absent. In contrast, pyrophosphate extractable Iron and Aluminum components are largely abundant in water-stable soil aggregates but not correlated to C, suggesting importance of these extracts to stabilize aggregates and

  12. Diffuse-reflectance mid-infrared spectroscopy reveals chemical differences in soil organic matter carried in different size wind eroded sediments

    NASA Astrophysics Data System (ADS)

    Padilla, Julio E.; Calderón, Francisco J.; Acosta-Martinez, Veronica; Van Pelt, Scott; Gardner, Terrence; Baddock, Matthew; Zobeck, Ted M.; Noveron, Juan C.

    2014-12-01

    Soil organic matter (SOM) is essential for soil water holding capacity, aggregation, and biodiversity. Little information is available regarding the carbon (C) functional groups carried away in wind eroded sediments away from the source soil. Mid-infrared (MidIR) spectroscopy was used on wind tunnel-blown sediments eroded from a loam soil during the fallow period of different cropping systems and tillage managements in Akron, Colorado. The soil was managed as fallow-winter wheat (Triticum aestivum L.) under conventional tillage (F-Wct) or no tillage (F-Wnt) and fallow-wheat-corn under no tillage (F-W-Cnt). Two wind eroded sediments were evaluated: fine dust (<35 μm mean dia.) and saltation-size material (<175 μm mean dia.). Our study showed that there is a partition of C groups within wind eroded sediments of different sizes and that they can reflect the tillage management history of soil. The fine dust had higher levels of aliphatic CH (2930 cm-1), and clays (3690-3620 cm-1). The saltation-sized material showed higher absorbance for quartz from 2000-1800 cm-1 and reduced absorbance from 1250-1050 cm-1. Both wind eroded sediments showed higher absorbance for -OH/NH groups and aliphatic CH from no-till soil. Finer dust sediments, which travel greater distances from the source soil than saltation size material, can carry away higher levels of aliphatic-carbon compounds and clays with potential negative impacts on SOM quantity and quality, and consequently the sustainability of these agroecosystems.

  13. Quantifying the eroded volume of mercury-contaminated sediment using terrestrial laser scanning at Stocking Flat, Deer Creek, Nevada County, California, 2010–13

    USGS Publications Warehouse

    Howle, James F.; Alpers, Charles N.; Bawden, Gerald W.; Bond, Sandra

    2016-01-01

    High-resolution ground-based light detection and ranging (lidar), also known as terrestrial laser scanning, was used to quantify the volume of mercury-contaminated sediment eroded from a stream cutbank at Stocking Flat along Deer Creek in the Sierra Nevada foothills, about 3 kilometers west of Nevada City, California. Terrestrial laser scanning was used to collect sub-centimeter, three-dimensional images of the complex cutbank surface, which could not be mapped non-destructively or in sufficient detail with traditional surveying techniques.The stream cutbank, which is approximately 50 meters long and 8 meters high, was surveyed on four occasions: December 1, 2010; January 20, 2011; May 12, 2011; and February 4, 2013. Volumetric changes were determined between the sequential, three-dimensional lidar surveys. Volume was calculated by two methods, and the average value is reported. Between the first and second surveys (December 1, 2010, to January 20, 2011), a volume of 143 plus or minus 15 cubic meters of sediment was eroded from the cutbank and mobilized by Deer Creek. Between the second and third surveys (January 20, 2011, to May 12, 2011), a volume of 207 plus or minus 24 cubic meters of sediment was eroded from the cutbank and mobilized by the stream. Total volumetric change during the winter and spring of 2010–11 was 350 plus or minus 28 cubic meters. Between the third and fourth surveys (May 12, 2011, to February 4, 2013), the differencing of the three-dimensional lidar data indicated that a volume of 18 plus or minus 10 cubic meters of sediment was eroded from the cutbank. The total volume of sediment eroded from the cutbank between the first and fourth surveys was 368 plus or minus 30 cubic meters.

  14. Structural features of cytochrome P450 1A associated with the absence of EROD activity in liver of the of the loricariid catfish Pterygoplichthys sp

    PubMed Central

    Parente, T.E.M.; Rebelo, M.F.; da-Silva, M.L.; Woodin, B.R.; Goldstone, J. V.; Bisch, P.M.; Paumgartten, F.J.R.; Stegeman, J.J.

    2011-01-01

    The Amazon catfish genus Pterygoplichthys (Loricariidae, Siluriformes) is closely related to the loricariid genus Hypostomus, in which at least two species lack detectable ethoxyresorufin-O-deethylase (EROD) activity, typically catalyzed by cytochrome P450 1 (CYP1) enzymes. Pterygoplichthys sp. liver microsomes also lacked EROD, as well as activity with other substituted resorufins, but aryl hydrocarbon receptor agonists induced hepatic CYP1A mRNA and protein suggesting structural/functional differences in Pterygoplichthys CYP1s from those in other vertebrates. Comparing the sequences of CYP1As of Pterygoplichthys sp. and of two phylogenetically-related siluriform species that do catalyze EROD (Ancistrus sp., Loricariidae and Corydoras sp., Callichthyidae) showed that these three proteins share amino acids at 17 positions that are not shared by any fish in a set of 24 other species. Pterygoplichthys and Ancistrus (the loricariids) have an additional 22 amino acid substitutions in common that are not shared by Corydoras or by other fish species. Pterygoplichthys has six exclusive amino acid substitutions. Molecular docking and dynamics simulations indicate that Pterygoplichthys CYP1A has a weak affinity for ER, which binds infrequently in a productive orientation, and in a less stable conformation than in CYP1As of species that catalyze EROD. ER also binds with the carbonyl moiety proximal to the heme iron. Pterygoplichthys CYP1A has amino acids substitutions that reduce the frequency of correctly oriented ER in the AS preventing the detection of EROD activity. The results indicate that loricariid CYP1As may have a peculiar substrate selectivity that differs from CYP1As of most vertebrates. PMID:21840383

  15. Quantifying the eroded volume of mercury-contaminated sediment using terrestrial laser scanning at Stocking Flat, Deer Creek, Nevada County, California, 2010–13

    USGS Publications Warehouse

    Howle, James F.; Alpers, Charles N.; Bawden, Gerald W.; Bond, Sandra

    2016-07-28

    High-resolution ground-based light detection and ranging (lidar), also known as terrestrial laser scanning, was used to quantify the volume of mercury-contaminated sediment eroded from a stream cutbank at Stocking Flat along Deer Creek in the Sierra Nevada foothills, about 3 kilometers west of Nevada City, California. Terrestrial laser scanning was used to collect sub-centimeter, three-dimensional images of the complex cutbank surface, which could not be mapped non-destructively or in sufficient detail with traditional surveying techniques.The stream cutbank, which is approximately 50 meters long and 8 meters high, was surveyed on four occasions: December 1, 2010; January 20, 2011; May 12, 2011; and February 4, 2013. Volumetric changes were determined between the sequential, three-dimensional lidar surveys. Volume was calculated by two methods, and the average value is reported. Between the first and second surveys (December 1, 2010, to January 20, 2011), a volume of 143 plus or minus 15 cubic meters of sediment was eroded from the cutbank and mobilized by Deer Creek. Between the second and third surveys (January 20, 2011, to May 12, 2011), a volume of 207 plus or minus 24 cubic meters of sediment was eroded from the cutbank and mobilized by the stream. Total volumetric change during the winter and spring of 2010–11 was 350 plus or minus 28 cubic meters. Between the third and fourth surveys (May 12, 2011, to February 4, 2013), the differencing of the three-dimensional lidar data indicated that a volume of 18 plus or minus 10 cubic meters of sediment was eroded from the cutbank. The total volume of sediment eroded from the cutbank between the first and fourth surveys was 368 plus or minus 30 cubic meters.

  16. Does market integration buffer risk, erode traditional sharing practices and increase inequality? A test among Bolivian forager-farmers

    PubMed Central

    Gurven, Michael; Jaeggi, Adrian V.; von Rueden, Chris; Hooper, Paul L.; Kaplan, Hillard

    2015-01-01

    Sharing and exchange are common practices for minimizing food insecurity in rural populations. The advent of markets and monetization in egalitarian indigenous populations presents an alternative means of managing risk, with the potential impact of eroding traditional networks. We test whether market involvement buffers several types of risk and reduces traditional sharing behavior among Tsimane Amerindians of the Bolivian Amazon. Results vary based on type of market integration and scale of analysis (household vs. village), consistent with the notion that local culture and ecology shape risk management strategies. Greater wealth and income were unassociated with the reliance on others for food, or on reciprocity, but wealth was associated with a greater proportion of food given to others (i.e., giving intensity) and a greater number of sharing partners (i.e., sharing breadth). Across villages, greater mean income was negatively associated with reciprocity, but economic inequality was positively associated with giving intensity and sharing breadth. Incipient market integration does not necessarily replace traditional buffering strategies but instead can often enhance social capital. PMID:26526638

  17. Fine gravel controls hydrologic and erodibility responses to trampling disturbance for coarse-textured soils with weak cyanobacterial crusts

    USGS Publications Warehouse

    Herrick, J.E.; Van Zee, J. W.; Belnap, J.; Johansen, J.R.; Remmenga, M.

    2010-01-01

    We compared short-term effects of lug-soled boot trampling disturbance on water infiltration and soil erodibility on coarse-textured soils covered by a mixture of fine gravel and coarse sand over weak cyanobacterially-dominated biological soil crusts. Trampling significantly reduced final infiltration rate and total infiltration and increased sediment generation from small (0.5m2) rainfall simulation plots (p<0.01). Trampling had no effect on time to runoff or time to peak runoff. Trampling had similar effects at sites with both low and very low levels of cyanobacterial biomass, as indicated by chlorophyll a concentrations. We concluded that trampling effects are relatively independent of differences in the relatively low levels of cyanobacterial biomass in this environment. Instead, trampling appears to reduce infiltration by significantly reducing the cover of gravel and coarse sand on the soil surface, facilitating the development of a physical crust during rainfall events. The results of this study underscore the importance of carefully characterizing both soil physical and biological properties to understand how disturbance affects ecosystem processes. ?? 2010.

  18. Does market integration buffer risk, erode traditional sharing practices and increase inequality? A test among Bolivian forager-farmers.

    PubMed

    Gurven, Michael; Jaeggi, Adrian V; von Rueden, Chris; Hooper, Paul L; Kaplan, Hillard

    2015-08-01

    Sharing and exchange are common practices for minimizing food insecurity in rural populations. The advent of markets and monetization in egalitarian indigenous populations presents an alternative means of managing risk, with the potential impact of eroding traditional networks. We test whether market involvement buffers several types of risk and reduces traditional sharing behavior among Tsimane Amerindians of the Bolivian Amazon. Results vary based on type of market integration and scale of analysis (household vs. village), consistent with the notion that local culture and ecology shape risk management strategies. Greater wealth and income were unassociated with the reliance on others for food, or on reciprocity, but wealth was associated with a greater proportion of food given to others (i.e., giving intensity) and a greater number of sharing partners (i.e., sharing breadth). Across villages, greater mean income was negatively associated with reciprocity, but economic inequality was positively associated with giving intensity and sharing breadth. Incipient market integration does not necessarily replace traditional buffering strategies but instead can often enhance social capital.

  19. Concerns about eroding the ethical barrier to in vitro eugenics: lessons from the hESC debate.

    PubMed

    Pugh, Jonathan

    2014-11-01

    In his discussion of in vitrogametogenesis, Rob Sparrow claims that an ethical barrier to development of this technology is that many jurisdictions currently prohibit the practice of creating embryos solely for the purpose of research. However, he suggests that this ethical barrier will soon be eroded, in view of the fact that in vitro gametogenesis could serve as a powerful new technology to overcome infertility. In this commentary, I argue that Sparrow is being overly optimistic in his analysis here. I claim that the debate over so-called compromise positions in the human embryonic stem cell debate suggests that the purpose of the research for which a research embryo is created is unlikely to be considered as having any significant bearing on the moral permissibility of the practice for those who oppose it. Even though in vitro gametogenesis could serve as a powerful new technology to overcome infertility, I argue that opponents of the practice of creating embryos solely for research purposes would still view the creation of research embryos that the development of in vitro gametogenesis would require, as being incompatible with affording the embryo proper moral respect. I conclude by suggesting that Sparrow's analysis of the potential benefits of in vitro gametogenesis provides us with further reasons to scrutinise the unconvincing arguments that are often cited in favour of prohibiting the practice of creating embryos solely for research purposes.

  20. The immediate effectiveness of barley straw mulch in reducing soil erodibility and surface runoff generation in Mediterranean vineyards.

    PubMed

    Prosdocimi, Massimo; Jordán, Antonio; Tarolli, Paolo; Keesstra, Saskia; Novara, Agata; Cerdà, Artemi

    2016-03-15

    Soil and water loss in agriculture is a major problem throughout the world, and especially in Mediterranean areas. Non-conservation agricultural practices have further aggravated the situation, especially in vineyards, which are affected by one of the highest rates of soil loss among cultivated lands. Therefore, it is necessary to find the right soil practices for more sustainable viticulture. In this regard, straw mulching has proven to be effective in other crop and fire affected soils, but, nonetheless, little research has been carried out in vineyards. This research tests the effect of barley straw mulching on soil erosion and surface runoff on vineyards in Eastern Spain where the soil and water losses are non-sustainable. An experiment was setup using rainfall simulation tests at 55 mm h(-1) over 1h on forty paired plots of 0.24 m(2): twenty bare and twenty straw covered. Straw cover varied from 48 to 90% with a median value of 59% as a result of the application of 75 g of straw per m(2). The use of straw mulch resulted in delayed ponding and runoff generation and, as a consequence, the median water loss decreased from 52.59 to 39.27% of the total rainfall. The straw cover reduced the median sediment concentration in runoff from 9.8 to 3.0 g L(-1) and the median total sediment detached from 70.34 to 15.62 g per experiment. The median soil erosion rate decreased from 2.81 to 0.63 Mg ha(-1)h(-1) due to the straw mulch protection. Straw mulch is very effective in reducing soil erodibility and surface runoff, and this benefit was achieved immediately after the application of the straw.

  1. Mass-height profile and total mass transport of wind eroded aeolian sediments from rangelands of the Indian Thar Desert

    NASA Astrophysics Data System (ADS)

    Mertia, R. S.; Santra, Priyabrata; Kandpal, B. K.; Prasad, R.

    2010-11-01

    Wind erosion is an active land degradation process in the Indian Thar Desert and severe dust storm events during hot summer months in the region are very common. Assessment of soil loss due to dust storm events from major land use systems of the Indian Thar Desert is highly essential for proper environmental planning. Characterization of the mass-height profile of wind eroded aeolian sediment is an important step to compute soil loss/mass transport but was not previously studied in the region. In the present study, aeolian mass fluxes (kg m -2) at different heights from soil surface were measured at two major rangelands in the Indian Thar Desert: Overgrazing rangeland at Jaisalmer (26°55'N and 70°57'E), and controlled grazing rangeland at Chandan (27°01'N and 71°01'E). Evaluation of several mass-height profile models revealed that a power decay function [ q( z) = az-b, where q( z) is the measured mass flux at an height of z (m) from soil surface; a and b are parameters of the equation] was best to characterize the mass-height relationship of aeolian sediments from the Indian Thar Desert. The average mass transport rate (kg m -1 day -1) or the total soil loss during hot summer months was significantly higher at the overgrazed rangeland site than at the controlled grazing rangeland site. Therefore, protection of existing rangelands, which comprise about 80% geographical area of the Indian Thar Desert may check the land degradation process due to wind erosion.

  2. Influence of Bristle Stiffness of Manual Toothbrushes on Eroded and Sound Human Dentin – An In Vitro Study

    PubMed Central

    Arnold, Wolfgang H.; Domin, Julia

    2016-01-01

    Aim The aim of this study was to determine the influence of manual toothbrushes with different bristle stiffness on the abrasivity on eroded and sound human dentin. Materials and Methods Dentin specimens were made from impacted third molars and attributed to three groups: erosion-abrasion (EA), abrasion (A) and erosion (E). The specimens from EA and E were treated with 1% citric acid (pH 2.3) for 1 min rinsed, and neutralized with artificial saliva for 15 min. This cycle was repeated five times. Thereafter, specimens from EA and A were treated with three toothbrushes types with different bristle stiffness (soft, medium, and hard) in a custom-made toothbrushing machine. The brushing was performed at a load of 3 N with a toothpaste slurry for 630 s. This procedure was repeated five times, in group EA after each erosion cycle. EA and A groups passed through five cycles with a total of 6300 strokes. The abrasivity was analyzed by contact-free profilometry. Kruskal-Wallis and Mann-Whitney U tests were performed for statistical analysis. Results With respect to bristle stiffness there was no statistically significant difference in dentin loss within the EA group. In group A, a statistically significantly higher dentin loss was found for the soft in comparison to the hard bristles. No statistically significant differences were measured between soft/medium and medium/hard toothbrushes. The amount of dentin loss from specimens in the EA group was significantly higher than in the A group. Conclusions Within the limitations of this study, the dentin loss in the Abrasion group was higher with soft bristles than with hard ones. This result might have an influence on the toothbrush recommendations for patients with non-carious cervical lesions. PMID:27070901

  3. The immediate effectiveness of barley straw mulch in reducing soil erodibility and surface runoff generation in Mediterranean vineyards.

    PubMed

    Prosdocimi, Massimo; Jordán, Antonio; Tarolli, Paolo; Keesstra, Saskia; Novara, Agata; Cerdà, Artemi

    2016-03-15

    Soil and water loss in agriculture is a major problem throughout the world, and especially in Mediterranean areas. Non-conservation agricultural practices have further aggravated the situation, especially in vineyards, which are affected by one of the highest rates of soil loss among cultivated lands. Therefore, it is necessary to find the right soil practices for more sustainable viticulture. In this regard, straw mulching has proven to be effective in other crop and fire affected soils, but, nonetheless, little research has been carried out in vineyards. This research tests the effect of barley straw mulching on soil erosion and surface runoff on vineyards in Eastern Spain where the soil and water losses are non-sustainable. An experiment was setup using rainfall simulation tests at 55 mm h(-1) over 1h on forty paired plots of 0.24 m(2): twenty bare and twenty straw covered. Straw cover varied from 48 to 90% with a median value of 59% as a result of the application of 75 g of straw per m(2). The use of straw mulch resulted in delayed ponding and runoff generation and, as a consequence, the median water loss decreased from 52.59 to 39.27% of the total rainfall. The straw cover reduced the median sediment concentration in runoff from 9.8 to 3.0 g L(-1) and the median total sediment detached from 70.34 to 15.62 g per experiment. The median soil erosion rate decreased from 2.81 to 0.63 Mg ha(-1)h(-1) due to the straw mulch protection. Straw mulch is very effective in reducing soil erodibility and surface runoff, and this benefit was achieved immediately after the application of the straw. PMID:26789370

  4. Polar polycyclic aromatic compounds from different coal types show varying mutagenic potential, EROD induction and bioavailability depending on coal rank.

    PubMed

    Meyer, Wiebke; Seiler, Thomas-Benjamin; Schwarzbauer, Jan; Püttmann, Wilhelm; Hollert, Henner; Achten, Christine

    2014-10-01

    Investigations of the bioavailability and toxicity of polycyclic aromatic compounds (PAC) have rarely considered the heterogeneity of coals and the impact of more polar PAC besides polycyclic aromatic hydrocarbons (PAH). Earlier, we investigated the toxicity of eight heterogeneous coals and their extracts. In the present study, the hazard potential with respect to mechanism-specific toxicity of polar fractions of dichloromethane extracts from coals was studied. Polar extract fractions of all coal types except for anthracite induced EROD activity (determined in RTL-W1 cells), independent of coal type (Bio-TEQs between 23 ± 16 and 52 ± 22 ng/g). The polar fractions of all bituminous coal extracts revealed mutagenic activity (determined using the Ames Fluctuation test). No significant mutation induction was detected for the polar extract fractions from the lignite, sub-bituminous coal and anthracite samples, which indicates a higher dependency on coal type for polar PAC here. Additionally, information on bioavailability was derived from a bioaccumulation test using the deposit-feeding oligochaete Lumbriculus variegatus which was exposed for 28 days to ground coal samples. Despite the high toxic potential of most coal extracts and a reduced biomass of Lumbriculus in bituminous coal samples, bioaccumulation of PAH and mortality after 28 days were found to be low. Limited bioaccumulation of PAH (up to 3.6 ± 3.8 mg/kg EPA-PAH) and polar PAC were observed for all coal samples. A significant reduction of Lumbriculus biomass was observed in the treatments containing bituminous coals (from 0.019 ± 0.004 g to 0.046 ± 0.011 g compared to 0.080 ± 0.025 g per replicate in control treatments). We conclude that bioavailability of native PAC from coals including polar PAC is low for all investigated coal types. In comparison to lignite, sub-bituminous coals and anthracite, the bioavailability of PAC from bituminous coals is slightly increased.

  5. Determination of the CYP1A-inducing potential of single substances, mixtures and extracts of samples in the micro-EROD assay with H4IIE cells.

    PubMed

    Schiwy, Andreas; Brinkmann, Markus; Thiem, Ines; Guder, Gabriele; Winkens, Kerstin; Eichbaum, Kathrin; Nüßer, Leonie; Thalmann, Beat; Buchinger, Sebastian; Reifferscheid, Georg; Seiler, Thomas-Benjamin; Thoms, Brigitte; Hollert, Henner

    2015-11-01

    This protocol describes a quantitative and robust 96-well-plate-reader-based assay for the measurement of ethoxyresorufin-O-deethylase (EROD) activity using the rat hepatoma cell line H4IIE. The assay can be used to determine the cytochrome P450 subfamily 1A (CYP1A)-inducing potential of single substances, as well as of mixtures and extracts of samples. It is based on the aryl hydrocarbon receptor (AhR)-mediated induction of cytochrome P450 enzymes (subfamily 1A) in cells after exposure to dioxins and dioxin-like compounds. One enzymatic reaction catalyzed by CYP1A is the deethylation of the exogenous substrate 7-ethoxyresorufin to the fluorescent product resorufin, which is measured as EROD activity in the assay. The CYP1A-inducing potential of a sample can be reliably quantified by comparing the EROD activity with the concentration-response curve of the standard substance 2,3,7,8-tetrachlorodibenzo-p-dioxin, which can be detected at concentrations down to the picogram per liter range. A researcher familiar with the procedure can process up to 160 samples with four wells each within 3 d. The series described uses four plates with three concentrations per sample, which can be easily scaled to accommodate different sample sizes. PMID:26448361

  6. Screening of dioxin-like compounds by complementary evaluation strategy utilising ELISA, micro-EROD, and HRGC-HRMS in soil and sediments from Montevideo, Uruguay.

    PubMed

    Levy, W; Brena, B M; Henkelmann, B; Bernhöft, S; Pirez, M; González-Sapienza, G; Schramm, K-W

    2014-08-01

    Polychlorinated dibenzo-p-dioxins (PCDD) and dibenzofurans (PCDF) are persistent, toxic, and bioaccumulate in the environment. Due to their high analytical costs, these compounds are hardly regulated and mostly not monitored in the Third World. To overcome this, bioassays have been proposed as low-cost alternative methods. Two of the most established bioanalytical tools, the dioxin antibody-based enzyme-linked immunosorbent assay ELISA and the micro-EROD bioassay are evaluated and compared to high resolution gas chromatography and high resolution mass spectrometry (HRGC/HRMS) analytical methodology. The methods were tested using thirteen soils and sediment samples selected from diverse sites in Montevideo, Uruguay. The WHO₂₀₀₅ total toxic equivalent (WHO₂₀₀₅-TEQ) of soils ranged from 2.4 to 2212 (ng WHO₂₀₀₅-TEQ/kg dry sample) and from 0.14 to 9.4 (ng WHO₂₀₀₅-TEQ/kg dry sample) in sediments. This study shows significant contamination related to dioxin-like compounds, particularly in sites where uncontrolled burnings were carried out. ELISA and micro-EROD bioassay correlated well with HRGC/HRMS, R Spearman 0.773 and 0.913, respectively and were highly correlated to each other, R Spearman 0.879. Preliminary threshold values of bioassay toxic equivalents of 330 (ng/kg dry sample) for the micro-EROD bioassay and 220 (ng/kg dry sample) for ELISA are proposed.

  7. Sudden Clearing of Estuarine Waters upon Crossing the Threshold from Transport to Supply Regulation of Sediment Transport as an Erodible Sediment Pool is Depleted: San Francisco Bay, 1999

    USGS Publications Warehouse

    Schoellhamer, D.H.

    2011-01-01

    The quantity of suspended sediment in an estuary is regulated either by transport, where energy or time needed to suspend sediment is limiting, or by supply, where the quantity of erodible sediment is limiting. This paper presents a hypothesis that suspended-sediment concentration (SSC) in estuaries can suddenly decrease when the threshold from transport to supply regulation is crossed as an erodible sediment pool is depleted. This study was motivated by a statistically significant 36% step decrease in SSC in San Francisco Bay from water years 1991-1998 to 1999-2007. A quantitative conceptual model of an estuary with an erodible sediment pool and transport or supply regulation of sediment transport is developed. Model results confirm that, if the regulation threshold was crossed in 1999, SSC would decrease rapidly after water year 1999 as observed. Estuaries with a similar history of a depositional sediment pulse followed by erosion may experience sudden clearing. ?? 2011 Coastal and Estuarine Research Federation (outside the USA).

  8. Towards a better understanding of the interaction between bed roughness and flow hydraulics in small eroded channels

    NASA Astrophysics Data System (ADS)

    Giménez, Rafael; Zubieta, Elena; Campo-Bescós, Miguel A.; Casalí, Javier

    2016-04-01

    Rills eroding cohesive materials are hydraulically different from rivers or large channels. Unlike rivers, rills are small, shallow flow stream with frequently a relatively steep slope gradient. Besides, rills evolve morphologically over much shorter timescales due to active bed erosion. This leads to a strong interaction between the channel flow and bed roughness. This interaction gives rise to a reconfiguration of the bed geometry generated by the important erosive action of the flow. This new shape is characterized by a typical alternance between concavities (pools) and more or less flat reaches (steps). The new rill geometry affects, in turn, the behaviour of the flow that is why we talk about interaction or feedback. In addition, the greatest energy dissipation occurs in the pools -mainly due to the action of hydraulic jumps- which, in turn, lead to an increase in the pool size. We hypothesize there is a regular spacing of step-pools units and that, both the frequency and the depth of the pools will be strongly conditioned by the discharge and the general rill slope. The determination of that periodicity (if any) would be an important contribution for concentrated flow erosion modelling of small channels. That is because the majority of erosion models are based on formulations which assume that a rill has a flat bed, only affected by micro-roughness. For instance, equations like Manning's - widely used in river and large channel hydraulics -, if a constant value of roughness is assumed, would be inappropriate in erosion rills since, as explained above, the roughness is not constant. The objectives of this work are then: (i) to investigate the geometry of erosion rills aiming at determining if there is a spatial arrangement of the macro roughness of their beds; and (ii) to establish (semi)-empirical models of prediction of this periodicity, mainly based on topographic parameters. Rills were generated in an agricultural field in a homogeneous hillslope (with no

  9. A surface-eroding poly(1,3-trimethylene carbonate) coating for fully biodegradable magnesium-based stent applications: toward better biofunction, biodegradation and biocompatibility.

    PubMed

    Wang, Juan; He, Yonghui; Maitz, Manfred F; Collins, Boyce; Xiong, Kaiqin; Guo, Lisha; Yun, Yeoheung; Wan, Guojiang; Huang, Nan

    2013-11-01

    Biodegradable magnesium-based materials have a high potential for cardiovascular stent applications; however, there exist concerns on corrosion control and biocompatibility. A surface-eroding coating of poly(1,3-trimethylene carbonate) (PTMC) on magnesium (Mg) alloy was studied, and its dynamic degradation behavior, electrochemical corrosion, hemocompatibility and histocompatibility were investigated. The PTMC coating effectively protected the corrosion of the Mg alloy in the dynamic degradation test. The corrosion current density of the PTMC-coated alloy reduced by three orders and one order of magnitude compared to bare and poly(ε-caprolactone) (PCL)-coated Mg alloy, respectively. Static and dynamic blood tests in vitro indicated that significantly fewer platelets were adherent and activated, and fewer erythrocytes attached on the PTMC-coated surface and showed less hemolysis than on the controls. The PTMC coating after 16 weeks' subcutaneous implantation in rats maintained ~55% of its original thickness and presented a homogeneously flat surface demonstrating surface erosion, in contrast to the PCL coated control, which exhibited non-uniform bulk erosion. The Mg alloy coated with PTMC showed less volume reduction and fewer corrosion products as compared to the controls after 52 weeks in vivo. Excessive inflammation, necrosis and hydrogen gas accumulation were not observed. The homogeneous surface erosion of the PTMC coating from exterior to interior (surface-eroding behavior) and its charge neutral degradation products contribute to its excellent protective performance. It is concluded that PTMC is a promising candidate for a surface-eroding coating applied to Mg-based implants.

  10. Effects of in ovo 2,3,7,8-TCDD exposure on hepatic ethoxyresorufin O-deethylase (EROD) induction and growth-related parameters in avian species

    SciTech Connect

    Janz, D.M.; Bellward, G.D.

    1994-12-31

    The effects of early in ovo TCDD exposure on CYP1A1 induction and indices of growth were determined in domestic chicken (Gallus gallus) and pigeon (Columba livia) hatchlings. TCDD (in corn oil) was injected into the air sac of eggs on embryonic day 4 (E4) (chickens, 0.1 {mu}g/kg egg; pigeons, 1.0 {mu}g/kg egg), and on E14 (pigeons, 3.0 {mu}g/kg egg). In chickens, hepatic EROD was induced 13, 15, 34, and 43-fold above control activities on E19, day of hatch (DO), day 2 after hatch (D2), and D4, respectively. Plasma thyroid hormone (T{sub 3} T{sub 4}) concentrations, which are known to peak during the perinatal period in chickens, were not affected by TCDD treatment when measured on E17, E19, D0, D2, and D4. In pigeons injected on E4, EROD was induced 15 and 6-fold on D0 and D7, respectively. There were significant decreases in yolk-free body weight, crown-rump, tibia, culmen, and wing lengths, and an elevated liver to body weight ratio (LSI) in TCDD-treated pigeons raised to D7 (p < 0.01). In pigeons injected on E14 (3{mu}g/kg), EROD was induced 14 and 10-fold on D0 and D7, respectively. Crown-rump and culmen lengths were decreased (p < 0.05) and LSI was increased (p < 0.01) on D0. There were significant decreases in all morphological parameters, and an increased LSI on D7 (p < 0.01) in TCDD-treated birds. These techniques will be used in further studies to investigate possible mechanisms of TCDD embryotoxicity in wild avian species, such as the great blue heron (Ardea herodias).

  11. Risk assessment of PCDD/Fs levels in human tissues related to major food items based on chemical analyses and micro-EROD assay.

    PubMed

    Tsang, H L; Wu, S C; Wong, C K C; Leung, C K M; Tao, S; Wong, M H

    2009-10-01

    Nine groups of food items (freshwater fish, marine fish, pork, chicken, chicken eggs, leafy, non-leafy vegetables, rice and flour) and three types of human samples (human milk, maternal serum and cord serum) were collected for the analysis of PCDD/Fs. Results of chemical analysis revealed PCDD/Fs concentrations (pg g(-1) fat) in the following ascending order: pork (0.289 pg g(-1) fat), grass carp (Ctenopharyngodon idellus) (freshwater fish) (0.407), golden thread (Nemipterus virgatus) (marine fish) (0.511), chicken (0.529), mandarin fish (Siniperca kneri) (marine fish) (0.535), chicken egg (0.552), and snubnose pompano (Trachinotus blochii) (marine fish) (1.219). The results of micro-EROD assay showed relatively higher PCDD/Fs levels in fish (2.65 pg g(-1) fat) when compared with pork (0.47), eggs (0.33), chicken (0.13), flour (0.07), vegetables (0.05 pg g(-1) wet wt) and rice (0.05). The estimated average daily intake of PCDD/Fs of 3.51 pg EROD-TEQ/kg bw/day was within the range of WHO Tolerable Daily Intake (1-4 pg WHO-TEQ/kg bw/day) and was higher than the Provisional Tolerable Daily Intake (PMTL) (70 pg for dioxins and dioxin-like PCBs) recommended by the Joint FAO/WHO Expert Committee on Food Additives (JECFA) [Joint FAO/WHO Expert Committee on Food Additives (JECFA), Summary and conclusions of the fifty-seventh meeting, JECFA, 2001.]. Nevertheless, the current findings were significantly lower than the TDI (14 pg WHO-TEQ/kg/bw/day) recommended by the Scientific Committee on Food of the Europe Commission [European Scientific Committee on Food (EU SCF), Opinions on the SCF on the risk assessment of dioxins and dioxin-like PCBs in food, 2000.]. However, it should be noted that micro-EROD assay overestimates the PCDD/Fs levels by 2 to 7 folds which may also amplify the PCDD/Fs levels accordingly. Although the levels of PCDD/Fs obtained from micro-EROD assay were much higher than those obtained by chemical analysis by 2 to 7 folds, it provides a cost-effective and

  12. Stochastic-deterministic modeling of bed load transport in shallow water flow over erodible slope: Linear stability analysis and numerical simulation

    NASA Astrophysics Data System (ADS)

    Bohorquez, Patricio; Ancey, Christophe

    2015-09-01

    In this article we propose a stochastic bed load transport formulation within the framework of the frictional shallow-water equations in which the sediment transport rate results from the difference between the entrainment and deposition of particles. First we show that the Saint-Venant-Exner equations are linearly unstable in most cases for a uniform base flow down an inclined erodible bed for Shields numbers in excess of the threshold for incipient sediment motion allowing us to compute noise-induced pattern formation for Froude numbers below 2. The wavelength of the bed forms are selected naturally due to the absolute character of the bed instability and the existence of a maximum growth rate at a finite wavelength when the particle diffusivity coefficient and the water eddy viscosity are present as for Turing-like instability. A numerical method is subsequently developed to analyze the performance of the model and theoretical results through three examples: the simulation of the fluctuations of the particle concentration using a stochastic Langevin equation, the deterministic simulation of anti-dunes formation over an erodible slope in full sediment-mobility conditions, and the computation of noise-induced pattern formation in hybrid stochastic-deterministic flows down a periodic flume. The full non-linear numerical simulations are in excellent agreement with the theoretical solutions. We conclude highlighting that the proposed depth-averaged formulation explains the developments of upstream migrating anti-dunes in straight flumes since the seminar experiments by Gilbert (1914).

  13. Benzo(a)pyrene Metabolism and EROD and GST Biotransformation Activity in the Liver of Red- and White-Blooded Antarctic Fish.

    PubMed

    Strobel, Anneli; Burkhardt-Holm, Patricia; Schmid, Peter; Segner, Helmut

    2015-07-01

    Climate change and anthropogenic pollution are of increasing concern in remote areas such as Antarctica. The evolutionary adaptation of Antarctic notothenioid fish to the cold and stable Southern Ocean led to a low plasticity of their physiological functions, what may limit their capacity to deal with altered temperature regimes and pollution in the Antarctic environment. Using a biochemical approach, we aimed to assess the hepatic biotransformation capacities of Antarctic fish species by determining (i) the activities of ethoxyresorufin-O-deethylase (EROD) and glutathione-S-transferase (GST), and (ii) the metabolic clearance of benzo(a)pyrene by hepatic S9 supernatants. In addition, we determined the thermal sensitivity of the xenobiotic biotransformation enzymes. We investigated the xenobiotic metabolism of the red-blooded Gobionotothen gibberifrons and Notothenia rossii, the hemoglobin-less Chaenocephalus aceratus and Champsocephalus gunnari, and the rainbow trout Oncorhynchus mykiss as a reference. Our results revealed similar metabolic enzyme activities and metabolic clearance rates between red- and white-blooded Antarctic fish, but significantly lower rates in comparison to rainbow trout. Therefore, bioaccumulation factors for metabolizable lipophilic contaminants may be higher in Antarctic than in temperate fish. Likewise, the thermal adaptive capacities and flexibilities of the EROD and GST activities in Antarctic fish were significantly lower than in rainbow trout. As a consequence, increasing water temperatures in the Southern Ocean will additionally compromise the already low detoxification capacities of Antarctic fish. PMID:25965896

  14. Benzo(a)pyrene Metabolism and EROD and GST Biotransformation Activity in the Liver of Red- and White-Blooded Antarctic Fish.

    PubMed

    Strobel, Anneli; Burkhardt-Holm, Patricia; Schmid, Peter; Segner, Helmut

    2015-07-01

    Climate change and anthropogenic pollution are of increasing concern in remote areas such as Antarctica. The evolutionary adaptation of Antarctic notothenioid fish to the cold and stable Southern Ocean led to a low plasticity of their physiological functions, what may limit their capacity to deal with altered temperature regimes and pollution in the Antarctic environment. Using a biochemical approach, we aimed to assess the hepatic biotransformation capacities of Antarctic fish species by determining (i) the activities of ethoxyresorufin-O-deethylase (EROD) and glutathione-S-transferase (GST), and (ii) the metabolic clearance of benzo(a)pyrene by hepatic S9 supernatants. In addition, we determined the thermal sensitivity of the xenobiotic biotransformation enzymes. We investigated the xenobiotic metabolism of the red-blooded Gobionotothen gibberifrons and Notothenia rossii, the hemoglobin-less Chaenocephalus aceratus and Champsocephalus gunnari, and the rainbow trout Oncorhynchus mykiss as a reference. Our results revealed similar metabolic enzyme activities and metabolic clearance rates between red- and white-blooded Antarctic fish, but significantly lower rates in comparison to rainbow trout. Therefore, bioaccumulation factors for metabolizable lipophilic contaminants may be higher in Antarctic than in temperate fish. Likewise, the thermal adaptive capacities and flexibilities of the EROD and GST activities in Antarctic fish were significantly lower than in rainbow trout. As a consequence, increasing water temperatures in the Southern Ocean will additionally compromise the already low detoxification capacities of Antarctic fish.

  15. Impact of leachate on groundwater pollution due to non-engineered municipal solid waste landfill sites of erode city, Tamil Nadu, India.

    PubMed

    Nagarajan, Rajkumar; Thirumalaisamy, Subramani; Lakshumanan, Elango

    2012-01-01

    Leachate and groundwater samples were collected from Vendipalayam, Semur and Vairapalayam landfill sites in Erode city, Tamil Nadu, India, to study the possible impact of leachate percolation on groundwater quality. Concentrations of various physicochemical parameters including heavy metals (Cd, Cr, Cu, Fe, Ni, Pb, Fe and Zn) were determined in leachate samples and are reported. The concentrations of Cl-, NO3-, SO42-, NH4+ were found to be in considerable levels in the groundwater samples particularly near to the landfill sites, likely indicating that groundwater quality is being significantly affected by leachate percolation. Further they were proved to be the tracers for groundwater contamination near Semur and Vendipalayam dumpyards. The presence of contaminants in groundwater particularly near the landfill sites warns its quality and thus renders the associated aquifer unreliable for domestic water supply and other uses. Although some remedial measures are suggested to reduce further groundwater contamination via leachate percolation, the present study demands for the proper management of waste in Erode city.

  16. Determining erodibility, critical shear stress, and allowable discharge estimates for cohesive channels: case study in the Powder River Basin of Wyoming

    SciTech Connect

    Thoman, R.W.; Niezgoda, S.L.

    2008-12-15

    The continuous discharge of coalbed natural gas-produced (CBNG-produced) water within ephemeral, cohesive channels in the Powder River Basin (PRB) of Wyoming can result in significant erosion. A study was completed to investigate channel stability in an attempt to correlate cohesive soil properties to critical shear stress. An in situ jet device was used to determine critical shear stress (tau{sub c}) and erodibility (k{sub d}); cohesive soil properties were determined following ASTM procedures for 25 reaches. The study sites were comprised of erodible to moderately resistant clays with tau{sub c} ranging from 0.11 to 15.35 Pa and k{sub d} ranging from 0.27 to 2.38 cm{sup 3}/N s. A relationship between five cohesive soil characteristics and tau{sub c} was developed and presented for use in deriving tau{sub c} for similar sites. Allowable discharges for CBNG-produced water were also derived using tau{sub c} and the tractive force method. An increase in the allowable discharge was found for channels in which vegetation was maintained. The information from this case study is critical to the development of a conservative methodology to establish allowable discharges while minimizing flow-induced instability.

  17. EROD activity and antioxidant defenses of sea bass (Dicentrarchus labrax) after an in vivo chronic hydrocarbon pollution followed by a post-exposure period.

    PubMed

    Danion, Morgane; Le Floch, Stéphane; Lamour, François; Quentel, Claire

    2014-12-01

    Chronic concentrations of polycyclic aromatic hydrocarbons (PAHs) have been commonly detected in international estuaries ecosystems. Reliable indicators still need to be found in order to properly assess the impact of PAHs in fish. After an in vivo chronic exposure to hydrocarbons, the enzymatic activity of 7-ethoxyresorufin O-deethylase (EROD) and the antioxidant defense system were assessed in sea bass, Dicentrarchus labrax. A total of 45 fish were exposed to the water-soluble fraction of Arabian crude oil, similar to a complex pollution by hydrocarbons chronically observed in situ, while 45 other control fish sustained the same experimental conditions in clean seawater. Fish samples were made after a 21-day exposure period and after a 15-day recovery period in clean fresh water. Throughout the experiment, liver EROD activity was significantly higher in contaminated fish than in control fish. In addition, nonenzymatic (total glutathione) and enzymatic (GPx, SOD, and CAT) antioxidant defense parameters measured in liver were not significantly different in fish. Furthermore, in gills, glutathione content had significantly increased while SOD activity had significantly decreased in contaminated fish compared to controls. On the other hand, CAT and GPx activities were not affected. Chronic exposure to PAHs disturbing the first step (SOD) and inhibiting the second step (GPx and CAT) could induce oxidative stress in tissues by the formation of oxygen radicals. After the postexposure period, there was no significant difference between control and contaminated fish in any of the antioxidant defense parameters measured in gills, attesting to the reversibility of the effects.

  18. Impact of leachate on groundwater pollution due to non-engineered municipal solid waste landfill sites of erode city, Tamil Nadu, India

    PubMed Central

    2012-01-01

    Leachate and groundwater samples were collected from Vendipalayam, Semur and Vairapalayam landfill sites in Erode city, Tamil Nadu, India, to study the possible impact of leachate percolation on groundwater quality. Concentrations of various physicochemical parameters including heavy metals (Cd, Cr, Cu, Fe, Ni, Pb, Fe and Zn) were determined in leachate samples and are reported. The concentrations of Cl-, NO3-, SO42-, NH4+ were found to be in considerable levels in the groundwater samples particularly near to the landfill sites, likely indicating that groundwater quality is being significantly affected by leachate percolation. Further they were proved to be the tracers for groundwater contamination near Semur and Vendipalayam dumpyards. The presence of contaminants in groundwater particularly near the landfill sites warns its quality and thus renders the associated aquifer unreliable for domestic water supply and other uses. Although some remedial measures are suggested to reduce further groundwater contamination via leachate percolation, the present study demands for the proper management of waste in Erode city. PMID:23369323

  19. Use of a Novel Double-Crested Cormorant ToxChip PCR Array and the EROD Assay to Determine Effects of Environmental Contaminants in Primary Hepatocytes.

    PubMed

    Crump, Doug; Farhat, Amani; Chiu, Suzanne; Williams, Kim L; Jones, Stephanie P; Langlois, Valerie S

    2016-03-15

    In vitro screening tools and 'omics methods are increasingly being incorporated into toxicity studies to determine mechanistic effects of chemicals and mixtures. To date, the majority of these studies have been conducted with well-characterized laboratory animal models. In the present study, well-established methods developed for chicken embryonic hepatocyte (CEH) studies were extended to a wild avian species, the double-crested cormorant (DCCO; Phalacrocorax auritus), in order to compare the effects of several environmental contaminants on cytotoxicity, ethoxyresorufin O-deethylase (EROD) activity, and mRNA expression. Five organic flame retardants and one plasticizer decreased cormorant hepatocyte viability in a similar manner to that observed in previous studies with CEH. EROD activity was induced in a concentration-dependent manner following exposure to two dioxin-like chemicals and the calculated EC50 values were concordant with domestic avian species from similar species sensitivity categories. Transcriptomic effects were determined using a novel DCCO PCR array, which was designed, constructed and validated in our laboratory based on a commercially available chicken PCR array. The DCCO array has 27 target genes covering a wide range of toxicity pathways. Gene profiles were variable among the 10 chemicals screened; however, good directional concordance was observed with regard to results previously obtained in CEH. Overall, the application of well-established methods (i.e., CEH and chicken PCR array) to the double-crested cormorant demonstrated the portability of the techniques to an indicator species of ecological relevance. PMID:26894911

  20. Induction of CYP1A in marine fish species from the Gulf of Mexico

    SciTech Connect

    Willett, K.L.; McDonald, S.; Narasimhan, T.R.; Connor, K.; Safe, S.; Kennicutt, M.C.

    1994-12-31

    Ethoxyresorufin O-deethylase (EROD) and aryl hydrocarbon hydroxylase (AHH) activities in over twenty species of fish, invertebrates, and fauna were used as biomarkers of exposure to polynuclear aromatic hydrocarbons (PAHs) in the Gulf of Mexico. The highest AHH and EROD activities in fish were detected in pinfish, tile, flounder, and hardhead catfish. In contrast, minimal to non-detectable induction was observed in invertebrates. Analysis of induction results showed that with the exception of a few species, there was a linear correlation between the induction of EROD vs AHH activity suggesting that ethoxyresorufin and benzo[a]pyrene serve as comparable substrates for CYP1A. In contrast, AHH activity was not induced in either hardhead catfish or lizard fish; whereas, the levels of EROD activity varied from 4.0 to 155 pmol/min/mg. These results indicate that there is some species-dependent variability in the catalytic activity of CYP1A protein in marine fish species, and that more reliable indicators of exposure to PAHs such as CYP1A mRNA levels should also be utilized in environmental monitoring studies. The results of Northern analysis of CYP1A mRNA levels in fish will be presented.

  1. Remineralization of eroded enamel by a NaF rinse containing a novel calcium phosphate agent in an in situ model: a pilot study

    PubMed Central

    Amaechi, Bennett T; Karthikeyan, Ramalingam; Mensinkai, Poornima K; Najibfard, Kaveh; Mackey, Allen C; Karlinsey, Robert L

    2010-01-01

    Purpose An in situ study evaluated the remineralization potential of 225 ppm fluoride (F) rinses with and without a calcium phosphate agent (TCP-Si-Ur) on eroded enamel. Methods 20 human patients participated in this IRB approved study. Enamel blocks extracted from 20 human molars were assigned to each of the three study phases (G1, G2, G3). Each block was eroded using 1% citric acid (pH = 2.5), with a slice cut from each block to establish baseline lesion parameters (ie, integrated mineral loss ΔZ, and lesion depth LD) using transverse microradiography (TMR). Participants and assigned blocks were randomly divided into three 28-day phases. The blocks were mounted into modified orthodontic brackets and bonded to the buccal surface of one of the subject’s mandibular molars. The appliance remained in the subject’s mouth for 28 days. Prior to each study phase, participants observed a one-week-washout period using a fluoride-free dentifrice. In each phase, participants brushed with the fluoride-free dentifrice for 1 min, followed by one of the following coded treatments: G1: 225 ppm F + 40 ppm TCP-Si-Ur rinse (1 min); G2: 225 ppm F rinse (1 min); G3: no rinse (saliva-only). After each phase, appliances were removed and specimens were analyzed using TMR. Results TMR data (ie, ΔZ and LD) revealed all three groups significantly remineralized eroded enamel (paired t-tests, P < 0.001). Net mineralization (% change in ΔZ, LD) were as follows (mean (std.dev): G1: 44.1 (22.6), 30.5 (27.0); G2: 30.0 (7.4), 29.4 (10.5); G3: 23.8 (16.4), 25.7 (15.5). Furthermore, G1 was found to cause significantly more remineralization than G2 (P = 0.039) and G3, (P = 0.002). Conclusion Mouthrinse containing 225 ppm F plus TCP-Si-Ur provided significantly greater remineralization relative to 225 ppm F only or saliva alone. PMID:23662086

  2. The distribution of secondary mineral phases along an eroding hillslope and its effect on carbon stabilization mechanisms and the fate of soil carbon fractions

    NASA Astrophysics Data System (ADS)

    Doetterl, Sebastian; Cornelis, Jean-Thomas; Opfergelt, Sophie; Boeckx, Pascal; Bodé, Samuel; Six, Johan; Van Oost, Kristof

    2014-05-01

    Soil redistribution processes can change soil carbon (C) dynamics drastically by moving carbon from high decomposition and re-sequestration environments at the eroding hillslope to low decomposition and burial at the depositional footslope and valley basin. This leads to not only spatially diverse soil carbon storage throughout the landscape, but also to qualitative changes of the transported carbon and the mineral phase. The interaction between those parameters and the effect on stabilization mechanisms for soil C are still a matter of debate. Here, we present an analysis that aims to clarify the bio/geo-chemical and mineralogical components involved in stabilizing C at various depths along an eroding cropped slope and how this affects the abundance of microbial derived carbon. We use the results of an incubation experiment combined with the abundance of amino sugars in different isolated soil C fractions as a tracer for the stability of the respective fraction. We applied further (i) a sequential extraction of the reactive soil phase using pyrophosphate, oxalate and dithionite-citrate-bicarbonate, and (ii) a qualitative analysis of the clay mineralogy, to analyze the changes in the mineral phase for the different isolated fractions along the slope transect. Our results emphasize the importance of physical protection within microaggregates to stabilize buried, chemically labile C. Our data further indicates that the stability of these aggregates is related to the presence of organo-mineral associations and poorly crystalline minerals. However, decreasing contents of these minerals with depth indicate a temporal limitation of this stabilization mechanism. Non-expandable clay minerals experience a relative enrichment at the depositional site while expandable clay minerals experience the same at the eroding site. These changes in clay mineralogy along the slope are partly responsible for the abundance of silt and clay associated C and the effectiveness of the clay

  3. Developmental toxicity, EROD, and CYP1A mRNA expression in zebrafish embryos exposed to dioxin-like PCB126.

    PubMed

    Liu, Han; Nie, Fang-Hong; Lin, Hong-Ying; Ma, Yi; Ju, Xiang-Hong; Chen, Jin-Jun; Gooneratne, Ravi

    2016-02-01

    Dioxin-like PCB126 is a persistent organic pollutant that causes a range of syndromes including developmental toxicity. Dioxins have a high affinity for aryl hydrocarbon receptor (AhR) and induce cytochrome P4501A (CYP1A). However, the role of CYP1A activity in developmental toxicity is less clear. To better understand dioxin induced developmental toxicity, we exposed zebrafish (Danio rerio) embryos to PCB126 at concentrations of 0, 16, 32, 64, and 128 μg L(-1) from 3-h post-fertilization (hpf) to 168 hpf. The embryonic survival rate decreased at 144 and 168 hpf. The fry at 96 hpf displayed gross developmental malformations, including pericardial and yolk sac edema, spinal curvature, abnormal lower jaw growth, and non-inflated swim bladder. The pericardial and yolk sac edema rate significantly increased and the heart rate declined from 96 hpf compared with the controls. PCB126 did not alter the hatching rate. To elucidate the mechanism of PCB126-induced developmental toxicity, we conducted ethoxyresorufin-O-deethylase (EROD) in vivo assay to determine CYP1A enzyme activity, and real-time PCR to study the induction of CYP1A mRNA gene expression in embryo/larval zebrafish at 24, 72, 96, and 132 hpf. In vivo EROD activity was induced by PCB126 at 16 μg L(-1) concentration as early as 72 hpf but significant increases were observed only in zebrafish exposed to 64 and 128 μg L(-1) doses (p < 0.005) at 72, 96, and 132 hpf. Induction of CYP1A mRNA expression was significantly upregulated in zebrafish exposed to 32 and 64 μg L(-1) at 24, 72, 96, and 132 hpf. Overall, the severe pericardial and yolk sac edema and reduced heart rate suggest that heart defects are a sensitive endpoint, and the general trend of dose-dependent increase in EROD activity and induction of CYP1A mRNA gene expression provide evidence that the developmental toxicity of PCB126 to zebrafish embryos is mediated by activation of AhR.

  4. Were Viking Dry-dock methods in the Americas used earlier to Build Pyramids, with Outflow Eroding the Sphinx, and were Stonehenge, the Obelisks, and Moas Similarly Erected?

    NASA Astrophysics Data System (ADS)

    McLeod, Edward; McLeod, Roger

    2006-03-01

    Chisel-quarried recycled granite in MA is datable by runes to 1069 CE; it could corroborate dating by a LIDAR. Associated sites, possibly used by Vikings to dry-dock their ships, could have exploited lock-like controls, possibly a continued technology. Site-leveling at the Giza Pyramids proves water was used. `Locks' and body-immersion worked for building, moving, erecting, or watering, at sites like Stonehenge, The Hanging Gardens at Babylon, the Moas of Easter Island, or The Pyramids, where the eroding water discharge was deliberately flushed over the Sphinx complex. It enhance the electromagnetically excited blue light signals we can detect, especially at sites frequented by Molocket of ME. Information, as at America's Stonehenge, in NH, and constructions at Acton MA, at Giza or at Rumford ME proves that the Pyramids and Sphinx were engineered and built about 4500 BP.

  5. Prevalence of certain inorganic constituents in groundwater samples of Erode district, Tamilnadu, India, with special emphasis on fluoride, fluorosis and its remedial measures.

    PubMed

    Karthikeyan, K; Nanthakumar, K; Velmurugan, P; Tamilarasi, S; Lakshmanaperumalsamy, P

    2010-01-01

    A total of 60 drinking water samples collected from Erode district, Tamilnadu, India were analysed for fluoride contamination, besides water quality parameters such as pH, electrical conductivity, total dissolved solids, total alkalinity, total hardness, fluoride, bicarbonates, calcium, magnesium, nitrate, sulphate, phosphate, sodium and potassium. The results obtained were found to exceed the permissible limits. The concentration of fluoride in the water samples ranged between 0.5 and 8.2 mg/l and revealed that 80% of the water samples contain fluoride above the maximum permissible limit. Similarly, the concentrations of nitrate, hardness, calcium and magnesium in some samples were also more than the permissible level. Pearson's correlation coefficient among the parameters showed a positive correlation of fluoride with total hardness and calcium. It is inferred from the study that these water sources can be used for potable purpose only after prior treatment.

  6. Silent spread of dengue and dengue haemorrhagic fever to Coimbatore and Erode districts in Tamil Nadu, India, 1998: need for effective surveillance to monitor and control the disease.

    PubMed

    Singh, J; Balakrishnan, N; Bhardwaj, M; Amuthadevi, P; George, E G; Subramani, K; Soundararajan, K; Appavoo, N C; Jain, D C; Ichhpujani, R L; Bhatia, R; Sokhey, J

    2000-08-01

    Dengue fever (DF) or dengue haemorrhagic fever (DHF) has not previously been reported in Coimbatore and Erode districts in Tamil Nadu in India. In 1998, 20 hospitalized cases of fever tested positive for dengue virus IgM and/or IgG antibodies. All of them had dengue-compatible illness, and at least four had DHF. Two of them died. Sixteen cases were below 10 years of age. The cases were scattered in 15 distantly located villages and 5 urban localities that had a high Aedes aegypti population. Although the incidence of dengue-like illness has not increased recently, almost 89% (95/107) of samples from healthy persons in the community tested positive for dengue IgG antibodies. The study showed that dengue has been endemic in the area, but was not suspected earlier. A strong laboratory-based surveillance system is essential to monitor and control DF/DHF.

  7. Sediment characterization, stocks and erodible relief quantification in alpine context using sloping local base level, from single watersheds to large-scale source-to-sink systems

    NASA Astrophysics Data System (ADS)

    Rudaz, Benjamin; Gavillet, Lauren; Jaboyedoff, Michel

    2014-05-01

    Erosion rates in alpine context since the last glacial maximum are classically calculated from accumulated sediments in glacial overdeepenings. Such erosion rates omit stored sediments in lateral valleys and secondary glacial troughs that have yet to get transported to the final sink. Their potential availability to the dominant mass wasting processes, such as landslides and debris-flows, is also important to assess, since sediment production and availability is a major driver of those hazardous phenomenon. In this study, a methodology to characterize sediment stocks and estimate their volume is applied to several watersheds, ranging from single torrential systems up to whole lateral valleys, and finally the complete source-to-sink system of the alpine Rhône river. First, areas occupied by colluvium, Holocene processes deposits and slope instabilities are mapped, using geological maps and HR-DEM hillshade. Each area is identified by its dominant formation process, and its situation in regard to glacially shaped valley geometry. For instance, glacial troughs are treated differently from valley walls and glacial cirques. The volume of sediments is given by subtracting a bedrock surface estimated with the SLBL methodology, with rock outcrops as fixed points, from the current topography. Where available, coring and geophysical data are used to constrain the geometry of the bedrock surface. Secondly, erodible relief is identified by considering the upper reaches of hydrologic networks as base levels. The volumes are constrained at the base with a slope angle derived from rock mechanics literature, thus changing with lithology, to emulate future potential slope movements towards the river network. The estimated stocks are then analyzed by process, age, and situation in the sediment cascade. The erodible relief allows localisation of future mass wasting potential, including the remobilization of existing stocks and future input from the still intact rock mass. The

  8. Effect of Root System Morphology on Root-sprouting and Shoot-rooting Abilities in 123 Plant Species from Eroded Lands in North-east Spain

    PubMed Central

    GUERRERO-CAMPO, JOAQUÍN; PALACIO, SARA; PÉREZ-RONTOMÉ, CARMEN; MONTSERRAT-MARTÍ, GABRIEL

    2006-01-01

    • Background and Aims The objective of this study was to test whether the mean values of several root morphological variables were related to the ability to develop root-borne shoots and/or shoot-borne roots in a wide range of vascular plants. • Methods A comparative study was carried out on the 123 most common plant species from eroded lands in north-east Spain. After careful excavations in the field, measurements were taken of the maximum root depth, absolute and relative basal root diameter, specific root length (SRL), and the root depth/root lateral spread ratio on at least three individuals per species. Shoot-rooting and root-sprouting were observed in a large number of individuals in many eroded and sedimentary environments. The effect of life history and phylogeny on shoot-rooting and root-sprouting abilities was also analysed. • Key Results The species with coarse and deep tap-roots tended to be root-sprouting and those with fine, fasciculate and long main roots (which generally spread laterally), tended to be shoot-rooting. Phylogeny had an important influence on root system morphology and shoot-rooting and root-sprouting capacities. However, the above relations stood after applying analyses based on phylogenetically independent contrasts (PICs). • Conclusions The main morphological features of the root system of the study species are related to their ability to sprout from their roots and form roots from their shoots. According to the results, such abilities might only be functionally viable in restricted root system morphologies and ecological strategies. PMID:16790468

  9. Restoration of eroded soil in the Sonoran Desert with native leguminous trees using plant growth-promoting microorganisms and limited amounts of compost and water.

    PubMed

    Bashan, Yoav; Salazar, Bernardo G; Moreno, Manuel; Lopez, Blanca R; Linderman, Robert G

    2012-07-15

    Restoration of highly eroded desert land was attempted in the southern Sonoran Desert that had lost its natural capacity for self-revegetation. In six field experiments, the fields were planted with three native leguminous trees: mesquite amargo Prosopis articulata, and yellow and blue palo verde Parkinsonia microphylla and Parkinsonia florida. Restoration included inoculation with two of plant growth-promoting bacteria (PGPB; Azospirillum brasilense and Bacillus pumilus), native arbuscular mycorrhizal (AM) fungi, and small quantities of compost. Irrigation was applied, when necessary, to reach a rainy year (300 mm) of the area. The plots were maintained for 61 months. Survival of the trees was marginally affected by all supplements after 30 months, in the range of 60-90%. This variation depended on the plant species, where all young trees were established after 3 months. Plant density was a crucial variable and, in general, low plant density enhanced survival. High planting density was detrimental. Survival significantly declined in trees 61 months after planting. No general response of the trees to plant growth-promoting microorganisms and compost was found. Mesquite amargo and yellow palo verde responded well (height, number of branches, and diameter of the main stem) to inoculation with PGPB, AM fungi, and compost supplementation after three months of application. Fewer positive effects were recorded after 30 months. Blue palo verde did not respond to most treatments and had the lowest survival. Specific plant growth parameters were affected to varying degrees to inoculations or amendments, primarily depending on the tree species. Some combinations of tree/inoculant/amendment resulted in small negative effects or no response when measured after extended periods of time. Using native leguminous trees, this study demonstrated that restoration of severely eroded desert lands was possible.

  10. Restoration of eroded soil in the Sonoran Desert with native leguminous trees using plant growth-promoting microorganisms and limited amounts of compost and water.

    PubMed

    Bashan, Yoav; Salazar, Bernardo G; Moreno, Manuel; Lopez, Blanca R; Linderman, Robert G

    2012-07-15

    Restoration of highly eroded desert land was attempted in the southern Sonoran Desert that had lost its natural capacity for self-revegetation. In six field experiments, the fields were planted with three native leguminous trees: mesquite amargo Prosopis articulata, and yellow and blue palo verde Parkinsonia microphylla and Parkinsonia florida. Restoration included inoculation with two of plant growth-promoting bacteria (PGPB; Azospirillum brasilense and Bacillus pumilus), native arbuscular mycorrhizal (AM) fungi, and small quantities of compost. Irrigation was applied, when necessary, to reach a rainy year (300 mm) of the area. The plots were maintained for 61 months. Survival of the trees was marginally affected by all supplements after 30 months, in the range of 60-90%. This variation depended on the plant species, where all young trees were established after 3 months. Plant density was a crucial variable and, in general, low plant density enhanced survival. High planting density was detrimental. Survival significantly declined in trees 61 months after planting. No general response of the trees to plant growth-promoting microorganisms and compost was found. Mesquite amargo and yellow palo verde responded well (height, number of branches, and diameter of the main stem) to inoculation with PGPB, AM fungi, and compost supplementation after three months of application. Fewer positive effects were recorded after 30 months. Blue palo verde did not respond to most treatments and had the lowest survival. Specific plant growth parameters were affected to varying degrees to inoculations or amendments, primarily depending on the tree species. Some combinations of tree/inoculant/amendment resulted in small negative effects or no response when measured after extended periods of time. Using native leguminous trees, this study demonstrated that restoration of severely eroded desert lands was possible. PMID:22425876

  11. Experimental study of PFCs erosion and eroded material deposition under ITER-like transient loads at the plasma gun facility QSPA-T

    NASA Astrophysics Data System (ADS)

    Klimov, N.; Podkovyrov, V.; Zhitlukhin, A.; Kovalenko, D.; Linke, J.; Pintsuk, G.; Landman, I.; Pestchanyi, S.; Bazylev, B.; Janeschitz, G.; Loarte, A.; Merola, M.; Hirai, T.; Federici, G.; Riccardi, B.; Mazul, I.; Giniyatulin, R.; Khimchenko, L.; Koidan, V.

    2011-08-01

    The paper concerns experimental investigations of plasma facing components erosion under the plasma heat loads expected in ITER divertor during transient events such as the Type I Edge-Localized Modes and the disruptions. The experiments were carried out at the TRINITI plasma gun QSPA-T. The carbon fiber composite and tungsten macrobrush targets designed for ITER were exposed to multiple plasma pulses of duration 0.5 ms and deposited energy in the range of 0.2-2.5 MJ/m2. Between some of the pulses the eroded surface was analyzed with profilometric measurements and electron microscopy. The CFC erosion is determined mainly by damages to the PAN-fibers. While the energy increases from 0.2 to 2.4 MJ/m2 the removed layer of PAN-fibers area increases from 0.01 to 10 μm per pulse. The erosion of tungsten (pure and lanthanum oxide-doped tungsten) is shown to be determined mainly by crack formation, melt layer movement and droplets ejection.

  12. Reconstructing the evoluortunity to study processes related to composite volction of an eroded Miocene caldera volcano (Yamanlar volcano, İzmir, Turkey)

    NASA Astrophysics Data System (ADS)

    Karaoğlu, Özgür; Brown, Richard J.

    2016-05-01

    The Miocene Yamanlar composite volcano is located in the central part of a shear zone in western Turkey. The volcano's deeply-eroded interior provides excellent three-dimensional exposure of a faulted caldera-floor and caldera-fill rocks as well as surrounding extracaldera ignimbrites. We present a much-revised stratigraphy and geological map of Yamanlar in order to quantify the evolutionary stages of the volcano. The Yamanlar volcanic cone was composed of > 800 m of basaltic-andesite to andesite lavas and lava domes. The volcano underwent at least one phase of caldera formation associated with an explosive eruption that deposited an ignimbrite sheet within and outside the caldera. Lithofacies architecture analysis is applied to the proximal and medial exposures of the Early-Middle Yamanlar Formation, which occurs outside of the caldera. Field evidence of the succession indicates a caldera-forming eruption. Our results indicate that the formation of the Yamanlar caldera resulted from one major catastrophic eruption that generated several sustained pyroclastic density currents (PDCs) subdivided by fall deposits with sharp contacts. The ignimbrite sheet is composed of four flow units. The presence of numerous coarse-grained lithic-rich horizons within the ignimbrite sheet is consistent with caldera subsidence. Post-caldera volcanism is indicated by intrusions and lava domes erupted along the inferred caldera-bounding faults, some of which record ~ 90 m of displacement. Widespread, coarse-grained breccias that overlie the ignimbrite sheet are interpreted as debris avalanche deposits resulting from gravitational failure of the flanks of the volcano or the caldera wall during or after caldera subsidence.

  13. Quantifying uranium transport rates and storage of fluvially eroded mine tailings from a historic mine site in the Grand Canyon Region

    NASA Astrophysics Data System (ADS)

    Skalak, K.; Benthem, A. J.; Walton-Day, K. E.; Jolly, G.

    2015-12-01

    The Grand Canyon region contains a large number of breccia pipes with economically viable uranium, copper, and silver concentrations. Mining in this region has occurred since the late 19th century and has produced ore and waste rock having elevated levels of uranium and other contaminants. Fluvial transport of these contaminants from mine sites is a possibility, as this arid region is susceptible to violent storms and flash flooding which might erode and mobilize ore or waste rock. In order to assess and manage the risks associated with uranium mining, it is important to understand the transport and storage rates of sediment and uranium within the ephemeral streams of this region. We are developing a 1-dimensional sediment transportation model to examine uranium transport and storage through a typical canyon system in this region. Our study site is Hack Canyon Mine, a uranium and copper mine site, which operated in the 1980's and is currently experiencing fluvial erosion of its waste rock repository. The mine is located approximately 40km upstream from the Colorado River and is in a deep, narrow canyon with a small watershed. The stream is ephemeral for the upper half of its length and sediment is primarily mobilized during flash flood events. We collected sediment samples at 110 locations longitudinally through the river system to examine the distribution of uranium in the stream. Samples were sieved to the sand size and below fraction (<2mm) and uranium was measured by gamma-ray spectroscopy. Sediment storage zones were also examined in the upper 8km of the system to determine where uranium is preferentially stored in canyon systems. This information will quantify the downstream transport of constituents associated with the Hack Canyon waste rock and contribute to understanding the risks associated with fluvial mobilization of uranium mine waste.

  14. Epidemiology of skeletal eroding band on the Great Barrier Reef and the role of injury in the initiation of this widespread coral disease

    NASA Astrophysics Data System (ADS)

    Page, C. A.; Willis, B. L.

    2008-06-01

    Skeletal eroding band (SEB), which manifests as dense aggregations of the ciliate Halofolliculina corallasia, was the first coral disease described from the Indo-Pacific. Little is known about its etiology or impact. This study describes the distribution, prevalence and host range of SEB on a 500 km extent of the Great Barrier Reef (GBR), together with in situ rates of progression and infection following experimental injury. SEB occurred on 90 100% of reefs surveyed ( n=18) in each of 3 years, demonstrating that SEB is widely distributed and persistent. SEB had the highest prevalence of any disease, affecting approximately 2% of 283,486 scleractinians and hydrocorals surveyed. Its host range was large, affecting 12 families and at least 82 scleractinian species, as well as the hydrocoral, Millepora. Corals in the families Pocilloporidae and Acroporidae were most susceptible, the former being up to five times more susceptible than other families. Progressive tissue loss was recorded on 95% of Acropora muricata colonies monitored ( n = 18), with rates of SEB progression averaging ˜2 mm/day . Injury experiments demonstrated that H. corallasia, the putative pathogen of SEB, readily colonised recently exposed coral skeleton in the absence of a vector, but did not colonise intact coral tissue. Invading ciliates failed to form band-like aggregations associated with progressive tissue loss on any of three coral species tested experimentally, suggesting that, while H. corallasia readily colonises recently exposed coral skeleton, it may not be sufficient in itself to cause tissue mortality. Interactions with additional agents or factors, increasing ciliate virulence or lowering disease resistance of coral hosts may be required before halofolliculinid infections become associated with tissue loss.

  15. Eroding permafrost coasts release low amounts of dissolved organic carbon (DOC) from ground ice into the nearshore zone of the Arctic Ocean

    NASA Astrophysics Data System (ADS)

    Tanski, George; Couture, Nicole; Lantuit, Hugues; Eulenburg, Antje; Fritz, Michael

    2016-07-01

    Ice-rich permafrost coasts in the Arctic are highly sensitive to climate warming and erode at a pace that exceeds the global average. Permafrost coasts deliver vast amounts of organic carbon into the nearshore zone of the Arctic Ocean. Numbers on flux exist for particulate organic carbon (POC) and total or soil organic carbon (TOC, SOC). However, they do not exist for dissolved organic carbon (DOC), which is known to be highly bioavailable. This study aims to estimate DOC stocks in coastal permafrost as well as the annual flux into the ocean. DOC concentrations in ground ice were analyzed along the ice-rich Yukon coast (YC) in the western Canadian Arctic. The annual DOC flux was estimated using available numbers for coast length, cliff height, annual erosion rate, and volumetric ice content in different stratigraphic horizons. Our results showed that DOC concentrations in ground ice range between 0.3 and 347.0 mg L-1 with an estimated stock of 13.6 ± 3.0 g m-3 along the YC. An annual DOC flux of 54.9 ± 0.9 Mg yr-1 was computed. These DOC fluxes are low compared to POC and SOC fluxes from coastal erosion or POC and DOC fluxes from Arctic rivers. We conclude that DOC fluxes from permafrost coasts play a secondary role in the Arctic carbon budget. However, this DOC is assumed to be highly bioavailable. We hypothesize that DOC from coastal erosion is important for ecosystems in the Arctic nearshore zones, particularly in summer when river discharge is low, and in areas where rivers are absent.

  16. [Soil anti-erodibility of abandoned lands during different succession stages of plant community in hilly-gullied region of the Loess Plateau: Take Fangta small watershed as an example].

    PubMed

    Yan, Fang-chen; Jiao, Ju-ying; Cao, Bin-ting; Yu, Wei-jie; Wei, Yan-hong; Kou, Meng; Hu, Shu

    2016-01-01

    Field survey and laboratory experiment were conducted to study the soil anti-erodibility of abandoned croplands during different vegetation succession stages in hilly-gullied region of the Loess Plateau, based on the analysis of soil particle composition, size distribution and group characteristics, soil aggregate fractal dimensions and stability. The results showed that in the earlier stages of succession from annual to perennial herbs in abandoned croplands, soil size distribution changed a little bit, the fractal dimension of soil particle increased, soil structure improved, fractal dimension and damage percent of soil aggregate structure decreased, soil stability increased, thus soil anti-erodibility increased. Therefore, natural restoration of vegetation is of great significance to improve the soil structure, increase soil erosion resistance, reduce soil erosion and promote sustainable development of regional ecological environment.

  17. Survey of receiving-water environmental impacts associated with discharges from pulp mills; 2: Gonad size, liver size, hepatic erod activity and plasma sex steroid levels in white sucker

    SciTech Connect

    Munkittrick, K.R.; Servos, M.R. . Great Lakes Lab. for Fisheries and Aquatic Sciences); Van Der Kraak, G.J.; McMaster, M.E. . Dept. of Zoology); Portt, C.B. ); Heuvel, M.R. van den . Dept. of Biology)

    1994-07-01

    Fish collected from the receiving areas of 12 Canadian pulp mills were examined, including sites receiving effluent from kraft mills using chlorine as well as sulfite mills. Field collections included sampling of receiving water for chemistry and toxicity testing, and sampling of local fish for organ weights, hepatic MFO (ethoxyresorufin-O-deethylase, EROD) activity, plasma steroid levels, and levels of liver dioxins. The main objectives of this study were to determine whether the discharge of effluent from pulp mills to sites other than Jackfish Bay was associated with physiological or biochemical disruptions in wild fish, whether there was any correlation between waste treatment and the presence of biological responses in wild fish, and whether there was any association between the use of chlorine as a bleaching agent and these responses. Although white sucker collected near bleached-kraft mills exhibited the highest EROD induction and dioxin levels, elevated enzyme activity was observed in fish from sites that did not use chlorine, and depressions in plasma sex steroid levels was not correlated with the level of EROD activity. The absence of chlorine bleaching or the presence of secondary treatment did not eliminate responses in fish, including decreased circulating levels of sex steroids, decreased gonadal size, and increase liver size. This survey has shown that (a) induction of hepatic EROD enzymes and depressions of plasma sex steroid levels during gonadal growth are found downstream of several pulp mills; (b) these changes are seen at some mills without chlorine bleaching and at mills that have secondary treatment; (c) substantial dilutions of nontoxic effluent do not appear to remove these responses; (d) the dominant factor determining the presence or absence of responses appeared to be dilution level; and (e) lab toxicity tests on invertebrates, rainbow trout, and fat-head minnows could not predict the presence of these responses in wild fish.

  18. Hepatic microsomal monooxygenase activity in black-crowned night herons (BCNHS) from the Chesapeake basin

    USGS Publications Warehouse

    Melancon, M.J.; Rattner, B.A.; Rice, C.P.; Hines, R.K.; Eisemann, J.

    1992-01-01

    In a continuation of our studies on the use of hepatic cytochromes P450 as a biomarker for contaminant exposure, BCNH eggs were collected from Baltimore Harbor (BH) (n = 20), Washington National Zoo (WNZ) (n = 13) and Chincoteague National Wildlife Refuge (CNWR) (reference location) (n = 20). Eggs were artificially incubated and sacrificed at pipping. Livers were snap frozen in liquid nitrogen and stored at -80?C until assay. Hepatic microsomes were prepared by differential centrifugation of homogenates and assayed for protein, benzyloxy-resorufin-O-dealkylase, (BROD) ethoxyresorufinO-dealkylase (EROD) and pentoxyresorufin-O-dealkylase (PROD). Monooxygenase assays were run in triplicate using a computer-coupled fluorometric microwell plate scanner. Values for EROD and BROD, but not PROD, from BH and WNZ were significantly greater (approximately double) than those from CNWR. Organochlorine pesticide residues were much higher in carcasses from BH and WNZ as compared to CNWR. Carcasses are presently being analyzed for PCB congeners.

  19. How does a single precipitation event erode a landscape? Clues from meteoric 7Be and 10Be analysis of suspended sediments and soils

    NASA Astrophysics Data System (ADS)

    Occhi, M.; Willenbring, J. K.; Kaste, J. M.; Scholl, M. A.; Shanley, J. B.

    2012-12-01

    Stream sediment contains a history recorded in isotopes that cling to suspended particles. In this study we exploit this recorded history in order to understand how a single precipitation event erodes the landscape at two watershed sites (Bisley I and Mameyes) within the Luquillo Critical Zone Observatory, Puerto Rico. We use fallout cosmogenic radionuclides Beryllium-7 (7Be) and Beryllium-10 (10Be) to determine the provenance of suspended sediment at various stages of a hydrograph. Sediments from source areas within the watersheds, such as stable ridge crests and active landslide scars, were also sampled and analyzed. Exploiting the large difference in half-life, the 10Be/7Be ratio of suspended sediments coupled with the concentration and nature of organic material present show original depth of mobilized stream sediment in the hillslope. The storm hydrographs of a one-month recurrence interval storm on June 7th, 2011 were sampled at both watersheds. In the small watershed (0.067 km2), storm discharge and total suspended solids (TSS) show short lag times between the initiation of precipitation and the initial rise of the hydrograph and no lag time between peak discharge and peak TSS. The larger site (17.8 km2) had a lag time of approximately 30 minutes between the initiation of precipitation and a rise in discharge and had a 15-minute lag between peak stage (which occurred first) and peak TSS, highlighting the longer travel distances that particles must take to reach the stream sampling point in the larger basin. We compare fallout 7Be nuclide concentration in source sediments and assume a simple, two end-member model to mix these sources in the stream. Soil sediments collected from stable ridge crests ('old') have relatively high average 7Be concentrations of 2.7x106 atoms/g±10% and sediments collected from active landslide scars ('new') have relatively low 7Be concentrations of 4.0x104 atoms/g±15%. Suspended sediments had an average 7Be concentration of 7.2x

  20. Induction of cytochrome P450-associated monooxygenases in northern leopard frogs, Rana pipiens, by 3,3',4,4',5-pentachlorobiphenyl

    USGS Publications Warehouse

    Huang, Y.-W.; Melancon, M.J.; Jung, R.E.; Karasov, W.H.

    1998-01-01

    Northern leopard frogs (Rana pipiens) were injected intraperitoneally either with a solution of polychlorinated biphenyl (PCB) 126 in corn oil at a concentration of 0.2, 0.7, 2.3 and 7.8 mg/kg body weight or with corn oil alone. Appropriate assay conditions with hepatic microsomes were determined for four cytochrome P450-associated monooxygenases: ethoxyresorufin-O-dealkylase (EROD), methoxy-ROD (MROD), benzyloxy-ROD (BROD) and pentoxy-ROD (PROD). One week after PCB administration, the specific activities of EROD, MROD, BROD and PROD were not elevated at doses ? 0.7 mg/kg (p > 0.05), but were significantly increased at doses ? 2.3 mg/kg compared to the control groups (p < 0.05). The increased activity of these four enzymes ranged from 3to 6.4fold relative to control levels. The increased activities were maintained for at least four weeks. Due to a lack of induction at low doses of PCB 126, which were still relatively high compared to currentlyknown environmental concentrations, we suspect that EROD, MROD, BROD, and PROD activities are not sensitive biomarkers for coplanar PCB exposure in leopard frogs.

  1. Induction of cytochrome P450-associated monooxygenases in northern leopard frogs, Rana pipiens, by 3,3{prime},4,4{prime},5-pentachlorobiphenyl

    SciTech Connect

    Huang, Y.; Jung, R.E.; Karasov, W.H.; Melancon, M.J.

    1998-08-01

    In the past decade, biochemical and physiological characteristics such as hepatic detoxifying system. DNA adducts, thyroid malfunction, and acetylcholinesterase inhibition have been used extensively as biomarkers for contaminant exposure. Northern leopard frogs (Rana pipiens) were injected intraperitoneally either with a solution of polychlorinated biphenyl (PCB) 126 m corn oil at a concentration of 0.2, 0.7, 2.3, or 7.8 mg/kg body weight or with corn oil alone. Appropriate assay conditions with hepatic microsomes were determined for four cytochrome P450-associated monooxygenases: ethoxyresorufin-O-dealkylase (EROD), methoxy-ROD (MROD), benzyloxy-ROD (BROD), and pentoxy-ROD (PROD). One week after PCB administration, the specific activities of EROD, MROD, BROD, and PROD were not elevated at doses {le}0.7 mg/kg (p > 0.05) but were significantly increased at doses {ge}2.3 mg/kg compared to the control groups (p < 0.05). The increased activities of these four enzymes were 3 to 6.4 times those in the control groups. The increased activities were maintained for at least 4 weeks. Because of a lack of induction at low doses of PCB 126, which were still relatively high compared to currently known environmental concentration, the authors suspect that EROD, MROD, BROD, and PROD activities are not sensitive biomarkers for coplanar PCB exposure in leopard frogs.

  2. Resprout and Survival of Willow ( Salix) Cuttings on Bioengineering Structures in Actively Eroding Gullies in Marls in a Mountainous Mediterranean Climate: A Large-Scale Experiment in the Francon Catchment (Southern Alps, France)

    NASA Astrophysics Data System (ADS)

    Rey, F.; Labonne, S.

    2015-10-01

    Improving the understanding of the role of vegetation and bioengineering structures on erosion and sedimentation control, especially in torrent-prone catchments in a mountainous Mediterranean climate, has become a key issue today for the scientific community working in ecological engineering and restoration ecology. The objective of this study was to evaluate the performance of willow ( Salix) cuttings in resprouting and survival on bioengineering structures in actively eroding gullies in marls and to identify the factors influencing this performance. Measurements were taken from 2008 to 2011 on 336 bioengineering structures, namely brush layers on wooden sills (BL) and brush layers with brush mats on wooden sills (BLM), using 8890 cuttings of Salix purpurea and Salix incana. These structures were built in 18 gullies of the Francon Catchment in marls (73 ha) in the Southern French Alps. After four growing seasons, the results revealed a total cutting survival rate of 45 %. They also demonstrated that in BLM, brush mats provided better survival (56 %) than brush layers (37 %). In BL, brush layers alone showed 51 % cutting survival. Cutting resprout and survival were observed for all structure aspects. They were positively related to increasing gully size and vegetation cover on gully sides. The results of this large-scale experiment clarified previous data obtained on a limited sample of bioengineering structures, providing further detail and showing that it is possible to use such structures made of willow cuttings to revegetate actively eroding gullies in marls within a mountainous Mediterranean climate.

  3. Resprout and Survival of Willow (Salix) Cuttings on Bioengineering Structures in Actively Eroding Gullies in Marls in a Mountainous Mediterranean Climate: A Large-Scale Experiment in the Francon Catchment (Southern Alps, France).

    PubMed

    Rey, F; Labonne, S

    2015-10-01

    Improving the understanding of the role of vegetation and bioengineering structures on erosion and sedimentation control, especially in torrent-prone catchments in a mountainous Mediterranean climate, has become a key issue today for the scientific community working in ecological engineering and restoration ecology. The objective of this study was to evaluate the performance of willow (Salix) cuttings in resprouting and survival on bioengineering structures in actively eroding gullies in marls and to identify the factors influencing this performance. Measurements were taken from 2008 to 2011 on 336 bioengineering structures, namely brush layers on wooden sills (BL) and brush layers with brush mats on wooden sills (BLM), using 8890 cuttings of Salix purpurea and Salix incana. These structures were built in 18 gullies of the Francon Catchment in marls (73 ha) in the Southern French Alps. After four growing seasons, the results revealed a total cutting survival rate of 45%. They also demonstrated that in BLM, brush mats provided better survival (56%) than brush layers (37%). In BL, brush layers alone showed 51% cutting survival. Cutting resprout and survival were observed for all structure aspects. They were positively related to increasing gully size and vegetation cover on gully sides. The results of this large-scale experiment clarified previous data obtained on a limited sample of bioengineering structures, providing further detail and showing that it is possible to use such structures made of willow cuttings to revegetate actively eroding gullies in marls within a mountainous Mediterranean climate.

  4. The interactions of 2,3,7,8-tetrachlorodibenzo-p-dioxin(TCDD) and 6-methyl-1,3,8-trichlorodibenzofuran (MCDF) in TCDD-induced porphyria

    SciTech Connect

    Yao, Cheng Catsby.

    1989-01-01

    Halogenated aryl hydrocarbon(HAH)-induced porphyria is caused by alteration of porphyrin metabolism and results in the accumulation of hepatic and urinary porphyrins. 2,3,7,8-Tetrachlorodibenzo-p-dioxin (75 {mu}/kg) caused significant increases of hepatic porphyrin levels in C57BL/6 male, female and ovariectomized female, and C57BL/10 male mice 3 weeks after treatment. In contrast, 6-methyl-1,3,8-trichlorodibenzofuran (MCDF) was inactive at a dose of 750 {mu}mol/kg. Cotreatment with MCDF (750 {mu}mol/kg) and 2,3,7,8-TCDD (75 {mu}g/kg) resulted in partial antagonism of 2,3,7,8-TCDD-induced porphyrin accumulation in female but not in male mice. In female C57BL/6 mice, 2,3,7,8-TCDD-induced porphyria was accompanied by the induction of hepatic microsomal aryl hydrocarbon hydroxylase (AHH) and ethoxyresorufin O-deethylase (EROD) activities and the inhibition of uroporphyrinogen decarboxylase (UROD) activity. MCDF (750 {mu}mol/kg) did not significantly affect these enzyme activities. In coadministration studies, MCDF partially antagonized 2,3,7,8-TCDD-induced hepatic porphyrin accumulation but did not affect the activities of hepatic AHH, EROD or UROD. These results demonstrate that the induction of the monooxygenase enzyme activities and the inhibition of UROD activity by 2,3,7,8-TCDD and the development of porphyria are not coordinately regulated in C57BL/6 female mice. In cultured chick embryo hepatocytes, 2,3,7,8-TCDD caused a significant increase in porphyrin levels and induced AHH and EROD activities. MCDF and Aroclor 1254 partially antagonized the 2,3,7,8-TCDD induced AHH and EROD activities but not the porphyrin accumulation.

  5. Environmental contaminant effects on juvenile striped bass in the San Francisco Estuary, California, USA.

    PubMed

    Spearow, Jimmy L; Kota, Rama S; Ostrach, David J

    2011-02-01

    The decline of pelagic organisms in the San Francisco Estuary (SFE) (California, USA) is attributed to several factors, including water diversions, invasive species, and exposure to environmental toxicants. The present study evaluated the effects of environmental contaminants on liver vitellogenin, metallothionein, 7-ethoxyresorufin-O-deethylase (EROD), and benzyloxyresorufin O-deethylase (BROD) activity in juvenile striped bass (Morone saxitilis) in the SFE. Analysis of juvenile striped bass liver extracts revealed site-specific elevations of vitellogenin, metallothionein, and EROD biomarkers across the estuary. Although some striped bass in the estuary showed EROD activity similar to unhandled hatchery controls, several sites in the estuary showed significantly higher EROD activity that was in the range of beta-naphthoflavone (BNF)-injected, positive controls. Overall, EROD activity averaged 283% higher in estuary fish than in hatchery controls. Chemical analyses of extracts from semipermeable membrane devices (SPMDs) deployed in the estuary for one month showed elevated polyaromatic hydrocarbon (PAH) levels. Semipermeable membrane devices extract injections-induced metallothionein and BROD in striped bass livers. These data show that environmental exposures are impacting EROD and other biomarkers in the SFE striped bass population. Previous studies in our laboratory have associated poor larval development with maternal transfer of environmental contaminants. Further studies are needed to monitor contaminant exposures by the use of biomarkers and to integrate them into a more effective pelagic species recovery plan in the SFE. PMID:21038432

  6. Environmental contaminant effects on juvenile striped bass in the San Francisco Estuary, California, USA.

    PubMed

    Spearow, Jimmy L; Kota, Rama S; Ostrach, David J

    2011-02-01

    The decline of pelagic organisms in the San Francisco Estuary (SFE) (California, USA) is attributed to several factors, including water diversions, invasive species, and exposure to environmental toxicants. The present study evaluated the effects of environmental contaminants on liver vitellogenin, metallothionein, 7-ethoxyresorufin-O-deethylase (EROD), and benzyloxyresorufin O-deethylase (BROD) activity in juvenile striped bass (Morone saxitilis) in the SFE. Analysis of juvenile striped bass liver extracts revealed site-specific elevations of vitellogenin, metallothionein, and EROD biomarkers across the estuary. Although some striped bass in the estuary showed EROD activity similar to unhandled hatchery controls, several sites in the estuary showed significantly higher EROD activity that was in the range of beta-naphthoflavone (BNF)-injected, positive controls. Overall, EROD activity averaged 283% higher in estuary fish than in hatchery controls. Chemical analyses of extracts from semipermeable membrane devices (SPMDs) deployed in the estuary for one month showed elevated polyaromatic hydrocarbon (PAH) levels. Semipermeable membrane devices extract injections-induced metallothionein and BROD in striped bass livers. These data show that environmental exposures are impacting EROD and other biomarkers in the SFE striped bass population. Previous studies in our laboratory have associated poor larval development with maternal transfer of environmental contaminants. Further studies are needed to monitor contaminant exposures by the use of biomarkers and to integrate them into a more effective pelagic species recovery plan in the SFE.

  7. A mass spectroscopic method for analysis of AHH-inducing and other polychlorinated biphenyl congeners and selected pesticides in fish

    USGS Publications Warehouse

    Schmidt, Larry J.; Hesselberg, Robert J.

    1992-01-01

    The 209 polychlorinated biphenyl (PCB) congeners exhibit a wide range in toxicity to fish, birds, and mammals. This paper discusses the use of gas chromatography/mass spectrometry negative chemical ionization (GC/MS-NCI) to quantify congeners of highly suspected toxicity such as IUPAC #77 (3,3',4,4'-tetrachlorobiphenyl) and #126 (3,3',4,4',5-pentachlorobiphenyl). GC/MS analysis time needed to produce the necessary resolution was reduced to 1 h per sample or standard, allowing an autosampler to inject 12 samples in 24 hours, plus 12 standards/QC samples. Identification and quantification of some 60+ congeners and several selected pesticides and estimation of total PCBs are also possible within the 1 h analysis. For congeners of high chlorination (penta through octa), the method exhibited excellent sensitivity, such that we could not locate a fish which exhibited PCB levels below our calibrated quantitation range. NCI was not as sensitive for mono through tri and for some tetrachlorinated PCB congeners, an exception being PCB #77, for which sensitivity was of the same order as for the more highly chlorinated biphenyls. Long term stability was excellent. Over a 6-mo period, results of replicate analyses for PCB congeners and pesticides in a composited sample of lake trout (Salvelinus namaycush) from Lake Michigan had a relative standard deviation of 12% of the mean. Over the same time period, mean recoveries for samples spiked at concentrations similar to those in Lake Michigan lake trout were 90-102%. Response was linear over a wide range of concentrations for each of the analyzed compounds. This method is now being used for routine analysis of PCB congeners and selected pesticides in our laboratory.

  8. Test of bioengineering structures in large eroded marly gullies (1 to 3 ha) in a mountainous and Mediterranean climate: resistance of the structures and survival of willow cuttings (Southern Alps, France)

    NASA Astrophysics Data System (ADS)

    Rey, Freddy; Labonne, Sophie; Dangla, Laure; Lavandier, Géraud

    2014-05-01

    In the Southern French Alps under a mountainous and Mediterranean climate, bioengineering structures installed in gully bottoms of highly weathered marly catchments aim at trapping a part of the eroded materials in order to reduce suspended sediment in the water system. They are made of brush layers and brush mats of cuttings on deadwood microdams. Purple and white Willows (Salix purpurea and S. incana) are used as they proved their efficiency to survive in such environment and efficiently trap marly sediment, but only in gullies with surface area less than 1 ha. Extrapolating their use to larger gullies could allow increasing the impact of such operations for reduction of sediment yield at the scale of large catchments. To this view, bioengineering structures have been built in spring and autumn 2010 in large eroded marly gullies with surface areas between 1 and 3 ha, in the Roubines and Fontaugier catchments (Southern Alps, France). 165 bioengineering structures (150 in spring and 15 in autumn) were built in 10 experimental gullies. After 3 observation years for each modality (2010 to 2012, and 2011 to 2013, respectively), the results revealed that 2/3 of the structures well resisted to damages due to concentrated flows. However, they were generally filled of sediment very rapidly, thus killing a large number of cuttings, particularly in the brush mats in gullies with surface area comprised between 2 and 3 ha. Therefore it has been proved that cuttings survival is possible in gullies with surface area less than 3 ha. In the French Southern Alps, bioengineering strategies have been improved by adding gullies of 1 to 3 ha in restoration plans. For gullies with surface area superior to 2 ha, it is recommended to first install the brush layers, and 1 to 2 years later the brush mats.

  9. Large-scale variability of wind erosion mass flux rates at Owens Lake 1. Vertical profiles of horizontal mass fluxes of wind-eroded particles with diameter greater than 50 μm

    USGS Publications Warehouse

    Gillette, Dale A.; Fryrear, D.W.; Xiao, Jing Bing; Stockton, Paul; Ono, Duane; Helm, Paula J.; Gill, Thomas E; Ley, Trevor

    1997-01-01

    A field experiment at Owens (dry) Lake, California, tested whether and how the relative profiles of airborne horizontal mass fluxes for >50-μm wind-eroded particles changed with friction velocity. The horizontal mass flux at almost all measured heights increased proportionally to the cube of friction velocity above an apparent threshold friction velocity for all sediment tested and increased with height except at one coarse-sand site where the relative horizontal mass flux profile did not change with friction velocity. Size distributions for long-time-averaged horizontal mass flux samples showed a saltation layer from the surface to a height between 30 and 50 cm, above which suspended particles dominate. Measurements from a large dust source area on a line parallel to the wind showed that even though the saltation flux reached equilibrium ∼650 m downwind of the starting point of erosion, weakly suspended particles were still input into the atmosphere 1567 m downwind of the starting point; thus the saltating fraction of the total mass flux decreased after 650 m. The scale length difference and ratio of 70/30 suspended mass flux to saltation mass flux at the farthest down wind sampling site confirm that suspended particles are very important for mass budgets in large source areas and that saltation mass flux can be a variable fraction of total horizontal mass flux for soils with a substantial fraction of <100-μm particles.

  10. Impact assessment: Eroding benefits through streamlining?

    SciTech Connect

    Bond, Alan; Pope, Jenny; Morrison-Saunders, Angus; Retief, Francois; Gunn, Jill A.E.

    2014-02-15

    This paper argues that Governments have sought to streamline impact assessment in recent years (defined as the last five years) to counter concerns over the costs and potential for delays to economic development. We hypothesise that this has had some adverse consequences on the benefits that subsequently accrue from the assessments. This hypothesis is tested using a framework developed from arguments for the benefits brought by Environmental Impact Assessment made in 1982 in the face of the UK Government opposition to its implementation in a time of economic recession. The particular benefits investigated are ‘consistency and fairness’, ‘early warning’, ‘environment and development’, and ‘public involvement’. Canada, South Africa, the United Kingdom and Western Australia are the jurisdictions tested using this framework. The conclusions indicate that significant streamlining has been undertaken which has had direct adverse effects on some of the benefits that impact assessment should deliver, particularly in Canada and the UK. The research has not examined whether streamlining has had implications for the effectiveness of impact assessment, but the causal link between streamlining and benefits does sound warning bells that merit further investigation. -- Highlights: • Investigation of the extent to which government has streamlined IA. • Evaluation framework was developed based on benefits of impact assessment. • Canada, South Africa, the United Kingdom, and Western Australia were examined. • Trajectory in last five years is attrition of benefits of impact assessment.

  11. Invasive Mutualists Erode Native Pollination Webs

    PubMed Central

    Aizen, Marcelo A; Morales, Carolina L; Morales, Juan M

    2008-01-01

    Plant–animal mutualisms are characterized by weak or asymmetric mutual dependences between interacting species, a feature that could increase community stability. If invasive species integrate into mutualistic webs, they may alter web structure, with consequences for species persistence. However, the effect of alien mutualists on the architecture of plant–pollinator webs remains largely unexplored. We analyzed the extent of mutual dependency between interacting species, as a measure of mutualism strength, and the connectivity of 10 paired plant–pollinator webs, eight from forests of the southern Andes and two from oceanic islands, with different incidences of alien species. Highly invaded webs exhibited weaker mutualism than less-invaded webs. This potential increase in network stability was the result of a disproportionate increase in the importance and participation of alien species in the most asymmetric interactions. The integration of alien mutualists did not alter overall network connectivity, but links were transferred from generalist native species to super-generalist alien species during invasion. Therefore, connectivity among native species declined in highly invaded webs. These modifications in the structure of pollination webs, due to dominance of alien mutualists, can leave many native species subject to novel ecological and evolutionary dynamics. PMID:18271628

  12. Acid rain erodes business profits, too

    SciTech Connect

    Not Available

    1980-11-01

    Evidence is mounting that acid rain may be more expensive, in the long run, than even the most sophisticated, costly pollution control. Unabated, the pollution will have increasingly devastating economic effects. It is difficult to quantify acid rain's economically damaging effects, since they vary considerably with soil quality. Well-buffered soils can tolerate greater quantities of acidic precipitation than can those not well-buffered. Unfortunately, some of the most susceptible areas of the country are also most dependent on agricultural ore recreational business for economic survival. Economically damaging effects vary: they can be either short- or long-term; reversible or irreversible. A partial list might include crop damage, long-term effects on forest growth, fisheries losses, long-term declines in property values on acidified lakes, effects on recreational industries in acid-sensitive areas, and costs incurred by having to treat chemically altered groundwater.

  13. Erodibility of fly ash-treated minesoils

    SciTech Connect

    Gorman, J.M.; Sencindiver, J.C.; Singh, R.N.

    1997-12-31

    Fly ash, a by-product of coal-fired power plants, has been used successfully in reclaiming adverse mine sites such as abandoned mine lands by improving minesoil chemical and physical properties. But, the fine sand-silt particle size of fly ash may make it more susceptible to detachment and transport by erosive processes. Furthermore, the high content of silt-size particles in fly ash may make it more susceptable to surface crust formation resulting in reduced infiltration and increased surface runoff and erosion. In the summer of 1989, fly ash/wood waste mixtures were surface applied on two separate mine sites, one with 10% slope and the other 20% slope, in central Preston County, West Virginia. Erosion rates were measured directly using the Linear Erosion/Elevation Measuring Instrument (LEMI). Erosion measurements were taken during the first two growing seasons on both sites. Erosion values were up to five times greater on the fly ash-treated minesoil than on the minesoil without fly ash cover. Mulching with wood chips reduced fly ash erosion to about one-half the loss of the unmulched plots. Erosion was related to both the amount and type of ground cover. Increased vegetative ground cover resulted in reduced erosion. Mosses and fungi appeared to provide better erosion protection than grass-legume cover.

  14. Induction of liver monooxygenases by annatto and bixin in female rats.

    PubMed

    De-Oliveira, A C A X; Silva, I B; Manhaes-Rocha, D A; Paumgartten, F J R

    2003-01-01

    Annatto or urucum is an orange-yellow dye obtained from Bixa orellana seeds. It has been used as a natural dye in a variety of food products, drugs and cosmetics, and also in Brazilian cuisine as a condiment ('colorau'). Bixin, a carotenoid devoid of provitamin A activity, is the main pigment found in annatto. Some carotenoids (canthaxanthin, astaxanthin and beta-Apo-8'-carotenal) are known to be potent inducers of CYP1A1, a property not shared by others (beta-carotene, lycopene and lutein). Little is known, however, about the CYP1A1-inducing properties of bixin and annatto. The present study was performed to determine the effects of an annatto extract (28% bixin) and bixin (95% pure) on rat liver monooxygenases. Adult female Wistar rats were treated by gavage with daily doses of annatto (250 mg/kg body weight, which contains approximately 70 mg bixin/kg body weight), bixin (250 mg/kg body weight) or the vehicle only (corn oil, 3.75 g/kg body weight) for 5 consecutive days, or were not treated (untreated control). The activities of aniline-4-hydroxylase (A4H), ethoxycoumarin-O-deethylase (ECOD), ethoxy- (EROD), methoxy- (MROD), pentoxy- (PROD) and benzyloxy- (BROD) resorufin-O-dealkylases were measured in liver microsomes. Annatto (250 mg/kg containing 70 mg bixin/kg) induced EROD (3.8x), MROD (4.2x), BROD (3.3x) and PROD (2.4x). Bixin (250 mg/kg) was a weaker inducer of EROD (2.7x), MROD (2.3x) and BROD (1.9x) and did not alter PROD, A4H or ECOD activities. These results suggest that constituents of the extract other than bixin play an important role in the induction of CYP1A and CYP2B observed with annatto food colorings. PMID:12532234

  15. Biomarker responses in the bivalve Chlamys farreri to the water-soluble fraction of crude oil

    NASA Astrophysics Data System (ADS)

    Jiang, Fenghua; Zhang, Li; Yang, Baijuan; Zheng, Li; Sun, Chengjun

    2015-07-01

    To investigate the effect of the water soluble fraction of crude oil (WSF) on marine bivalves, the scallop Chlamys farreri was exposed to three WSF concentrations (0.18 mg/L, 0.32 mg/L, and 0.51 mg/L, respectively) in seawater. Petroleum hydrocarbon contents in scallops and a suite of enzymes [7-Ethoxyresorufin-O-deethylase (EROD), aryl hydrocarbon hydroxylase (AHH), glutathione S-transferase (GST), and glutathione peroxidase (GPx)] in gills and digestive glands were monitored over 10 days. The results revealed that WSF affected the activity of the four enzymes in the gills and digestive glands. EROD activity in the gills was significantly induced in most individuals of the three test groups, while in the digestive gland it was significantly induced in the low-concentration group within 4 days but was inhibited in the middle- and high-concentration groups on days 1, 4, and 10. AHH activity in the gills of all treatment groups was significantly induced on day 1. In the digestive gland, AHH activity was induced in most individuals from the treatment groups. In all treatment groups, GST activity was significantly inhibited from days 2 to 10 in the gills and was induced after day 4 in the digestive gland. GPx activity in the gills was significantly inhibited throughout the exposure period in all treatment groups. There was no overall significant difference in GPx activity in the digestive gland between the control and treatment groups. Our results also revealed that petroleum hydrocarbon concentrations in the tissues increased linearly with exposure time. EROD activity in the digestive gland and GST and GPx activity in the gill tissue were negatively correlated with petroleum hydrocarbon body burden. These enzymes play important roles in detoxification and can act as potential biomarkers for monitoring petroleum hydrocarbon contaminants in the marine environment.

  16. Comparison of basal and induced cytochromes P450 in 6 species of waterfowl

    USGS Publications Warehouse

    Melancon, M.J.; Rattner, B.A.; Hoffman, D.J.; Beeman, D.; Day, D.; Custer, T.

    1999-01-01

    Cytochrome P450-associated monooxygenase activities were measured in control and prototype inducer-treated mallard duck, black duck, wood duck, lesser scaup, Canada goose and mute swan. Ages of the birds ranged from pipping embryos (that were treated approximately 3 days before pipping) to adults. Three or more of the following hepatic microsomal monooxygenases were assayed in each species: Benzyloxyresorufin-O-dealkylase (BROD), Ethoxyresorufin-O-dealkylase (EROD), methoxyresorufin-O-dealkylase (MROD), and pentoxyresorufin-O-dealkylase (PROD). Baseline activities differed between species, but because of differences in ages, sources of the eggs or birds, and diets, these cannot be viewed as absolute differences. The cytochrome P450 inducers utilized were beta-naphthoflavone (BNF), 3-methylcholanthrene (3MC) and phenobarbital (PB). In general, there was little response to PB; only lesser scaup were induced to greater than three times control level and most species were well under this. Responses to BNF and 3MC occurred in each species studied, but differed in which of the monooxygenases was most induced (absolute values and ratios to control values) and in relative induction between species. BROD frequently had an induction ratio EROD. Overall, lesser scaup were the most responsive, canada geese the least responsive, and the other species intermediate in responsiveness to the cytochrome P450 inducers studied.

  17. Effects of Baicalin on Oral Pharmacokinetics of Caffeine in Rats

    PubMed Central

    Noh, Keumhan; Nepal, Mahesh Raj; Jeong, Ki Sun; Kim, Sun-A; Um, Yeon Ji; Seo, Chae Shin; Kang, Mi Jeong; Park, Pil-Hoon; Kang, Wonku; Jeong, Hye Gwang; Jeong, Tae Cheon

    2015-01-01

    Scutellaria baicalensis is one of the most widely used herbal medicines in East Asia. Because baicalein and baicalin are major components of this herb, it is important to understand the effects of these compounds on drug metabolizing enzymes, such as cytochrome P450 (CYP), for evaluating herb-drug interaction. The effects of baicalin and baicalein on activities of ethoxyresorufin O-deethylase (EROD), methoxyresorufin O-demethylase (MROD), benzyloxyresorufin O-debenzylase (BROD), p-nitrophenol hydroxylase and erythromycin N-demethylase were assessed in rat liver microsomes in the present study. In addition, the pharmacokinetics of caffeine and its three metabolites (i.e., paraxanthine, theobromine and theophylline) in baicalin-treated rats were compared with untreated control. As results, EROD, MROD and BROD activities were inhibited by both baicalin and baicalein. However, there were no significant differences in the pharmacokinetic parameters of oral caffeine and its three metabolites between control and baicalin-treated rats. When the plasma concentration of baicalin was determined, the maximum concentration of baicalin was below the estimated IC50 values observed in vitro. In conclusion, baicalin had no effects on the pharmacokinetics of caffeine and its metabolites in vivo, following single oral administration in rats. PMID:25767690

  18. Biological fate and effects of propranolol in an experimental aquatic food chain.

    PubMed

    Ding, Jiannan; Lu, Guanghua; Li, Sheng; Nie, Yang; Liu, Jianchao

    2015-11-01

    The aim of this study was to evaluate the trophic transfer of the β-blocker propranolol (PRP) in an experimental aquatic food chain involving the green algae Scenedesmus obliquus, the water flea Daphnia magna and the crucian carp Carassius auratus, as well as the metabolism and effects of PRP in the liver of crucian carp. After a 48 h PRP aqueous exposure for algae, with a subsequent 48 h dietary exposure for daphnia and an 8d dietary exposure for crucian carp, PRP was observed in each trophic level, despite significant bioaccumulation did not occur in daphnia and crucian carp. A portion of the absorbed PRP was metabolized by the crucian carp to N-desisopropylated propranolol, propranolol glucuronic acid, monohydroxylated propranolol, hydroxypropranolol glucuronide and dihydroxypropranolol glucuronide, which were similar to those in mammals. In addition, multiple biomarkers in the liver of crucian carp (7-ethoxyresorufin O-deethylase, EROD; 7-benzyloxyresorufin O-dealkylation, BROD; superoxide dismutase, SOD and malondialdehyde, MDA) were measured. BROD and MDA were not significantly affected by PRP, while EROD and SOD did change significantly during the 8d dietary exposure. This work indicated that the trophic transfer of PRP, resulting in biochemical perturbations of fish biological systems, should be a concern for the assessment of the environmental risks to aquatic food chains.

  19. Organochlorine accumulation by Sentinel Mallards at the Winston-Thomas sewage treatment plant, Bloomington, Indiana

    USGS Publications Warehouse

    Custer, T.W.; Sparks, D.W.; Sobiech, S.A.; Hines, R.K.; Melancon, M.J.

    1996-01-01

    Farm-raised l2-month-old female mallards (Anas platyrhynchos) were released at the Winston-Thomas sewage treatment plant, Bloomington, Indiana. Five mallards were sacrificed at the start of the study and at approximately 10-day intervals through day 100. Concentrations of polychlorinated biphenyls (PCBs) in carcasses increased linearly with time of exposure and exceeded 16 mcg/g wet weight by day 100; PCBs in breast muscle exceeded 3.9 mcg/g by day 100. These PCB values are among the highest recorded for wild or sentinel waterfowl. PCB concentrations in breast muscle (26-523 mcg/g lipid weight) were 50-1,000 times greater than human consumption guidelines for edible poultry in Canada (0.5 mcg/g lipid weight) and 9-176 times greater than consumption guidelines for edible poultry in the United States (3.0 mcg/g lipid weight). Additionally, PCB concentrations in carcass and breast muscle exceeded the threshold of the Great Lakes Sport Fish Consumption Advisory 'do not eat' category (1.9 mcg/g wet weight) by day 20 and day 50, respectively. Hepatic cytochrome P450-associated monooxygenases including BROD (benzyloxyresorufin-O-dealkylase), EROD (ethoxyresorufin-O-dealkylase), and PROD (pentoxyresorufin-O-dealkylase) were induced over 5-fold compared to reference mallards. BROD, EROD, and PROD were each significantly correlated to total PCBs and to the toxicity of selected PCB congeners, relative to 2,3,7,8-tetrachlorodibenzo-p-dioxin.

  20. Organochlorine accumulation by sentinel mallards at the Winston-Thomas sewage treatment plant, Bloomington, Indiana

    USGS Publications Warehouse

    Custer, T.W.; Sparks, D.W.; Sobiech, S.A.; Hines, R.K.; Melancon, M.J.

    1996-01-01

    Farm-raised 12-month-old female mallards (Anas platyrhynchos) were released at the Winston-Thomas sewage treatment plant, Bloomington, Indiana. Five mallards were sacrificed at the start of the study and at approximately 10-day intervals through day 100. Concentrations of polychlorinated biphenyls (PCBs) in carcasses increased linearly with time of exposure and exceeded 16 g/g wet weight by day 100; PCBs in breast muscle exceeded 3.9 g/g by day 100. These PCB values are among the highest recorded for wild or sentinel waterfowl. PCB concentrations in breast muscle (26a??523 g/g lipid weight) were 50a??1,000 times greater than human consumption guidelines for edible poultry in Canada (0.5 g/g lipid weight) and 9a??176 times greater than consumption guidelines for edible poultry in the United States (3.0 g/g lipid weight). Additionally, PCB concentrations in carcass and breast muscle exceeded the threshold of the Great Lakes Sport Fish Consumption Advisory do not eat category (1.9 g/g wet weight) by day 20 and day 50, respectively. Hepatic cytochrome P450-associated monooxygenases including BROD (benzyloxyresorufin-O-dealkylase), EROD (ethoxyresorufin-O-dealkylase), and PROD (pentoxyresorufin-O-dealkylase) were induced over 5-fold compared to reference mallards. BROD, EROD, and PROD were each significantly correlated to total PCBs and to the toxicity of selected PCB congeners, relative to 2,3,7,8-tetrachlorodibenzo-p-dioxin.

  1. Kinetics of hepatic phase I and II biotransformation reactions in eight finfish species.

    PubMed

    González, Jaime Fernando; Reimschuessel, Renate; Shaikh, Badar; Kane, Andrew S

    2009-01-01

    Hepatic microsomes and cytosols of channel catfish (Ictalurus punctatus), rainbow trout (Oncorhynchus mykiss), Atlantic salmon (Salmo salar), red tilapia (Oreochromis sp.), largemouth bass (Micropterussalmoides), striped bass (Morone saxatilis), hybrid striped bass (M. saxatilis x M. crysops), and bluegill (Lepomis macrochuris) (n=8) were used to study the kinetics of phase I (ECOD, EROD, PROD, BROD) and phase II (UDP-glucuronosyltransferase (UDPGT)-, sulfotransferase (ST)- and glutathione-s-transferase (GST)-mediated) reactions. The best catalytic efficiency for ECOD and GST activities was performed by channel catfish, Atlantic salmon, rainbow trout and tilapia. The highest EROD catalytic efficiency was for Atlantic salmon. None of the species had either PROD or BROD activities. Rainbow trout had very similar UDPGT catalytic efficiency to tilapia, channel catfish, Atlantic salmon, largemouth bass and bluegill. Sulfotransferase conjugation had no significant differences among the species. In summary, tilapia, channel catfish, Atlantic salmon and rainbow trout had the best biotransforming capabilities; striped bass, hybrid striped bass and bluegill were low metabolizers and largemouth bass shared some capabilities with both groups.

  2. Inter-relation of cytochrome P450 and contaminants burdens in sibling heron embryos and nestlings

    SciTech Connect

    Rattner, B.; Melancon, M.; Custer, T.; Hothem, R. ||

    1995-12-31

    Hepatic cytochrome P450-associated monooxygenase activities were measured in 11-day-old nestling black-crowned night-herons (Nycticorax nycticorax) collected from a reference site (next to the Chincoteague National Wildlife Refuge, Virginia) and three polluted sites (Cat Island, Green Bay, Lake Michigan, Wisconsin; Bair Island, San Francisco Bay, California; West Marin Island, San Francisco Bay, California). Activities of aryl hydrocarbon hydroxylase (AHH) and benzyl-oxyresorufin-O-dealkylase (BROD) were modestly elevated ({<=} three-fold) in nestlings from polluted sites. Concentrations of p,p{prime}DDE, other organochlorine pesticides and total PCBs in nestlings were greatest at contaminated sites, although much lower than found in concurrently collected eggs and pipping embryos, At these low pollutant concentrations there was little correlation between monooxygenase activity and contaminant levels in nestlings. These observations markedly contrast the pronounced monooxygenase induction (up to 85-fold) and its significant correlation with total PCBS, aryl hydrocarbon receptor-active PCB congeners and toxic equivalents in concurrently collected night-heron embryos that were often siblings of the nestlings. The present findings suggest that cytochrome P450-associated monooxygenase activity of heron nestlings may have only limited value as a biomarker of exposure at this rapid-growth life stage.

  3. Inter-relation of cytochrome P450 and contaminants burdens in sibling heron embryos and nestlings

    USGS Publications Warehouse

    Rattner, B.; Melancon, M.; Custer, T.; Hothem, R.

    1995-01-01

    Hepatic cytochrome P450-associated monooxygenase activities were measured in 11-day-old nestling black-crowned night-herons (Nycticorax nycticorax) collected from a reference site (next to the Chincoteague National Wildlife Refuge, Virginia) and three polluted sites (Cat Island, Green Bay, Lake Michigan, Wisconsin; Bair Island, San Francisco Bay, California; West Marin Island, San Francisco Bay, California). Activities of arylhydrocarbon hydroxylase (AHH) and benzyl-oxyresorufin-O-dealkylase (BROD) weremodestly elevated (

  4. Cytochrome P450 and contaminant concentrations in nestling black-crowned night-herons and their interrelation with sibling embryos

    USGS Publications Warehouse

    Rattner, B.A.; Melancon, M.J.; Custer, T.W.; Hothem, R.L.

    1996-01-01

    Hepatic cytochrome P450-associated monooxygenase activities were measured in 11-day-old nestling black-crowned night-herons (Nycticorax nycticorax) collected from a reference site (next to Chincoteague National Wildlife Refuge, VA) and three contaminated sites (Cat Island, Green Bay, WI; Bair Island, San Francisco Bay, CA; West Marin Island, San Francisco Bay, CA). Arylhydrocarbon hydroxylase (AHH) and benzyloxyresorufin-O-dealkylase (BROD) activities of nestlings from contaminated sites were only slightly elevated (less than threefold) compared to the reference site. Organochlorine pesticide and total PCB concentrations in nestlings were greatest at contaminated sites, although much lower than found in concurrently collected eggs and pipping embryos. Pollutant concentrations of nestlings were rarely associated with monooxygenase activity. In contrast, concurrently collected pipping heron embryos (often siblings of the nestlings) exhibited pronounced monooxygenase induction (means at contaminated sites elevated up to sevenfold and values of some embryos exceeded 25-fold induction). Furthermore, monooxygenase activity of pipping embryos was significantly correlated with total PCBs, arylhydrocarbon receptor-active PCB congeners and toxic equivalents. The modest monooxygenase responses of heron nestlings suggest that this biomarker may have only limited value during this rapid-growth life stage.

  5. Aryl hydrocarbon hydroxylase in cultured lymphocytes of twins.

    PubMed Central

    Paigen, B; Ward, E; Steenland, K; Houten, L; Gurtoo, H L; Minowada, J

    1978-01-01

    Measurement of aryl hydrocarbon hydroxylase (AHH) in cultured lymphocytes of 18 monozygotic and 30 dizygotic twin pairs showed that basal and induced AHH activity and AHH inducibility are heritable traits. The data are consistent with AHH inducibility being determined by a single or a very few polymorphic genes. PMID:569973

  6. E2 potentializes benzo(a)pyrene-induced hepatic cytochrome P450 enzyme activities in Nile tilapia at high concentrations.

    PubMed

    Rodrigues, Aline Cristina Ferreira; Moneró, Tatiana de Oliveira; Frighetto, Rosa Toyoko Shiraishi; de Almeida, Eduardo Alves

    2015-11-01

    In the aquatic environment, biotransformation enzymes are established biomarkers for assessing PAH exposure in fish, but little is known about the effect of 17β-estradiol (E2) on these enzymes during exposure to benzo(a)pyrene (BaP). In this study, Nile tilapia (Oreochromis niloticus) were exposed for 3, 5, and 10 days to BaP (300 μg L(-1)) and E2 (5 μg L(-1)). These substances were applied isolated or mixed. In the mixture experiment, fish were analyzed pre- and postexposure in order to better understand whether preexposure to the hormone masks the responses activated by PAH or vice versa. Phase I enzymes ethoxyresorufin-O-deethylase (EROD), pentoxyresorufin-O-depenthylase (PROD), and benzyloxyresorufin-O-debenzylase (BROD) activities as well as the phase II enzyme glutathione S-transferase (GST) were analyzed. Isolated E2 treatment decreased EROD activity after 3 days, but this enzyme activity returned to control values after 5 and 10 days of exposure. Isolated BaP treatment significantly induced EROD activity after 3 and 5 days, and the activity returned to control levels after ten exposure days. Combined treatment (E2 + Bap) significantly increased EROD activity, both in the pre- and postexposure. This increase was even higher than in the isolated BaP treatment, suggesting a synergism between these two compounds. When E2 and BaP were used singly, they did not change BROD and PROD activities. However, combined treatment (E2 + Bap) significantly increased PROD activity. Isolated BaP treatment increased GST activity after 10 days. However, this response was not observed in the mixture treatment, suggesting that E2 suppressed the GST induction modulated by BaP. The results put together indicated that E2 altered the biotransformation pathway regarding enzymes activated by BaP in Nile tilapia.

  7. Extra-articular Synovial Chondromatosis Eroding and Penetrating the Acromion.

    PubMed

    El Rassi, George; Matta, Jihad; Hijjawi, Ayman; Khair, Ousama Abou; Fahs, Sara

    2015-10-01

    Synovial chondromatosis of the shoulder is an uncommon disorder. It usually affects the glenohumeral joint and is characterized by metaplasia of the synovium leading to the formation of osteochondral loose bodies. Few cases of extra-articular subacromial synovial chondromatosis involving the rotator cuff tendon have been reported in the literature. The treatment of previously reported cases consisted of open bursectomy and removal of loose bodies. We report a case of subacromial synovial chondromatosis without rotator cuff involvement but with severe erosion and fracture of the acromion. Treatment consisted of shoulder arthroscopy to remove all loose bodies, total bursectomy, and debridement of the acromion. Potential benefits of arthroscopy were also evaluated. PMID:26697302

  8. Extra-articular Synovial Chondromatosis Eroding and Penetrating the Acromion

    PubMed Central

    El Rassi, George; Matta, Jihad; Hijjawi, Ayman; Khair, Ousama Abou; Fahs, Sara

    2015-01-01

    Synovial chondromatosis of the shoulder is an uncommon disorder. It usually affects the glenohumeral joint and is characterized by metaplasia of the synovium leading to the formation of osteochondral loose bodies. Few cases of extra-articular subacromial synovial chondromatosis involving the rotator cuff tendon have been reported in the literature. The treatment of previously reported cases consisted of open bursectomy and removal of loose bodies. We report a case of subacromial synovial chondromatosis without rotator cuff involvement but with severe erosion and fracture of the acromion. Treatment consisted of shoulder arthroscopy to remove all loose bodies, total bursectomy, and debridement of the acromion. Potential benefits of arthroscopy were also evaluated. PMID:26697302

  9. In vivo rehardening of enamel eroded by a cola drink.

    PubMed

    Kim, J W; Jang, K T; Lee, S H; Kim, C C; Hahn, S H; García-Godoy, F

    2001-01-01

    There are many concerns about the erosive effects of acidic beverages. In this study, the effects of Pepsi-Cola (pH 2.41) on bovine enamel and the rehardening effect resulting from intraoral exposure of the teeth were determined by microhardness testing (Vicker's Hardness Number). Bovine enamel specimens (VHN 380.00 +/- 12.74) were immersed in 100 ml of Pepsi-Cola for five minutes and subsequently exposed to human intraoral environment through the use of a removable resin plate. Microhardness testing was performed on specimens after one hour, twenty-four hours and forty-eight hours of exposure to an intraoral environment. The microhardness value was significantly (p < 0.05) reduced by the cola beverage (VHN 262.13 +/- 20.34), and significantly (p < 0.05) increased after intraoral exposure for one hour (VHN 299.75 +/- 26.86) and twenty-four hours (VHN 328.00 +/- 18.70). The difference in the microhardness between the twenty-four-hour group and the forty-eight-hour group (VHN 333.50 +/- 15.13) was not significant (p > 0.05). The microhardness value of the forty-eight-hour group was significantly less than the values recorded during the initial pre-study measurements p < 0.05).

  10. Wind Erodibility of Biosolids - Amended Soils: A Status Report

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Metro Wastewater Reclamation District in Denver has been applying municipal biosolids to agricultural land known as the METROGRO Farm since 1993. The farm, located approximately 105 km (65 mi) east of Denver, is in an area historically susceptible to wind erosion. Since biosolids can potentially i...

  11. Ocean acidification erodes crucial auditory behaviour in a marine fish

    PubMed Central

    Simpson, Stephen D.; Munday, Philip L.; Wittenrich, Matthew L.; Manassa, Rachel; Dixson, Danielle L.; Gagliano, Monica; Yan, Hong Y.

    2011-01-01

    Ocean acidification is predicted to affect marine ecosystems in many ways, including modification of fish behaviour. Previous studies have identified effects of CO2-enriched conditions on the sensory behaviour of fishes, including the loss of natural responses to odours resulting in ecologically deleterious decisions. Many fishes also rely on hearing for orientation, habitat selection, predator avoidance and communication. We used an auditory choice chamber to study the influence of CO2-enriched conditions on directional responses of juvenile clownfish (Amphiprion percula) to daytime reef noise. Rearing and test conditions were based on Intergovernmental Panel on Climate Change predictions for the twenty-first century: current-day ambient, 600, 700 and 900 µatm pCO2. Juveniles from ambient CO2-conditions significantly avoided the reef noise, as expected, but this behaviour was absent in juveniles from CO2-enriched conditions. This study provides, to our knowledge, the first evidence that ocean acidification affects the auditory response of fishes, with potentially detrimental impacts on early survival. PMID:21632617

  12. Soil water retention within an eroded and restored landscape

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Significant changes in soil properties and productivity have occurred as a result of intensive row crop production. Many of these changes are related to soil loss from water, wind, and tillage erosion. Soil is lost from convex and steeper landscape positions and deposited in concave lower landscape ...

  13. Water resource structures and the importance of erodibility

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Mirtskhoulava said, "Erosion is one of the least reliably defined elements of many hydraulic projects. Therefore, description and prediction of non-scouring velocities is one of the most important problems of hydraulics and river morphology." This quote and the recent experiences related to the er...

  14. Sustainability: a view from the wind-eroded field.

    PubMed

    Warren, Andrew

    2007-01-01

    This article explores the assessment of sustainability in fields subject to wind erosion. In the first part, simple sustainability audits are examined, as of soil depth and nutrients. Direct measurement of these characteristics has many problems, largely because of huge variability in space and time at all scales. Modelling still has its problems, but it may be possible to overcome many of them soon. It is true that wind erosion preferentially removes soil nutrients, but there are imponderables even here. The nutrient balance in many of these soils includes considerable input from dust. In West Africa, it has been shown that the amounts of calcium and potassium that are added in dust are sufficient to fertilize dispersed crops. In mildly acidic sandy soils, such as those found on the widespread palaeoaeolian deposits, much of the phosphorus is fixed and unavailable to plants by the time it is removed by wind erosion, so that erosion has no added downside. Most of the nutrients carried by dust have been shown to travel close to the ground (even when they are attached to dust-sized particles), and so are trapped in nearby fallow strips, and are thus not lost to the farming system. Second, the sustainability of a whole semi-arid farming system is explored. Wind erosion in semi-arid areas (like China, the Sahel and Northwestern Europe) generally takes place on aeolian deposits of the recent geological past. Most of these soils are deep enough to withstand centuries of wind erosion before they are totally lost to production, and some of these soils have greater fertility at greater depth (so that wind erosion may even improve the soil). Finally some remarks are made about environmental change in relation to sustainability.

  15. Axial cracks in pressurized eroded autofrettaged thick cylinders

    NASA Astrophysics Data System (ADS)

    Becker, A. A.; Plant, R. C. A.; Parker, A. P.

    1993-09-01

    The stress intensity factors associated with longitudinal axial cracks in pressurized autofrettaged thick cylinders are calculated using the boundary element (BE) method. The effect on the stress intensity factors of the presence of a semicircular erosion on the bore is investigated. Two loading cases are considered: internal pressure and autofrettage residual stresses. The residual stresses are incorporated by using a crack face loading based on the principle of superposition. The effect of the erosions and cracks on the fatigue lifetimes is calculated using the Paris law.

  16. Tillage and nutrient sources impact the productivity of eroded soil

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soil degradation is a consequence of soil organic matter (SOM) losses due to soil disturbance, SOM decomposition, and soil erosion. Manure addition has been shown to enhance SOM, improve soil nutrient status, and increase soil productivity. Manure rates and degree of incorporation may also influenc...

  17. Journalism and science: how to erode the idea of knowledge.

    PubMed

    Meyer, Gitte

    2006-01-01

    This paper discusses aspects of the relationship between the scientific community and the public at large. Inspired by the European public debate on genetically modified crops and food, ethical challenges to the scientific community are highlighted. This is done by a discussion of changes that are likely to occur to journalistic attitudes--mirroring changing attitudes in the wider society--towards science and scientific researchers. Two journalistic conventions--those of science transmission and of investigative journalism--are presented and discussed in relation to the present drive towards commercialization within the world of science: how are journalists from these different schools of thought likely to respond to the trend of commercialization? Likely journalistic reactions could, while maintaining the authority of the scientific method, be expected to undermine public trust in scientists. In the long term, this may lead to an erosion of the idea of knowledge as something that cannot simply be reduced to the outcome of negotiation between stakeholders. It is argued that science is likely to be depicted as a fallen angel. This may be countered, it is posited, by science turning human, by recognizing its membership of society, and by recognizing that such membership entails more than just commercial relations. To rethink its relationship with the public at large--and, in particular, to rethink the ideal of disinterested science--is an ethical challenge facing the scientific community.

  18. Parameterization of erodibility in the Rangeland Hydrology and Erosion Model

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The magnitude of erosion from a hillslope is governed by the availability of sediment and connectivity of runoff and erosion processes. For undisturbed rangelands, sediment is primarily detached and transported by rainsplash and sheetflow (splash-sheet) processes in isolated bare batches, but sedime...

  19. Sustainability: a view from the wind-eroded field.

    PubMed

    Warren, Andrew

    2007-01-01

    This article explores the assessment of sustainability in fields subject to wind erosion. In the first part, simple sustainability audits are examined, as of soil depth and nutrients. Direct measurement of these characteristics has many problems, largely because of huge variability in space and time at all scales. Modelling still has its problems, but it may be possible to overcome many of them soon. It is true that wind erosion preferentially removes soil nutrients, but there are imponderables even here. The nutrient balance in many of these soils includes considerable input from dust. In West Africa, it has been shown that the amounts of calcium and potassium that are added in dust are sufficient to fertilize dispersed crops. In mildly acidic sandy soils, such as those found on the widespread palaeoaeolian deposits, much of the phosphorus is fixed and unavailable to plants by the time it is removed by wind erosion, so that erosion has no added downside. Most of the nutrients carried by dust have been shown to travel close to the ground (even when they are attached to dust-sized particles), and so are trapped in nearby fallow strips, and are thus not lost to the farming system. Second, the sustainability of a whole semi-arid farming system is explored. Wind erosion in semi-arid areas (like China, the Sahel and Northwestern Europe) generally takes place on aeolian deposits of the recent geological past. Most of these soils are deep enough to withstand centuries of wind erosion before they are totally lost to production, and some of these soils have greater fertility at greater depth (so that wind erosion may even improve the soil). Finally some remarks are made about environmental change in relation to sustainability. PMID:17915712

  20. Intensive agriculture erodes β-diversity at large scales.

    PubMed

    Karp, Daniel S; Rominger, Andrew J; Zook, Jim; Ranganathan, Jai; Ehrlich, Paul R; Daily, Gretchen C

    2012-09-01

    Biodiversity is declining from unprecedented land conversions that replace diverse, low-intensity agriculture with vast expanses under homogeneous, intensive production. Despite documented losses of species richness, consequences for β-diversity, changes in community composition between sites, are largely unknown, especially in the tropics. Using a 10-year data set on Costa Rican birds, we find that low-intensity agriculture sustained β-diversity across large scales on a par with forest. In high-intensity agriculture, low local (α) diversity inflated β-diversity as a statistical artefact. Therefore, at small spatial scales, intensive agriculture appeared to retain β-diversity. Unlike in forest or low-intensity systems, however, high-intensity agriculture also homogenised vegetation structure over large distances, thereby decoupling the fundamental ecological pattern of bird communities changing with geographical distance. This ~40% decline in species turnover indicates a significant decline in β-diversity at large spatial scales. These findings point the way towards multi-functional agricultural systems that maintain agricultural productivity while simultaneously conserving biodiversity.

  1. Use of manure to remediate eroded hill top soils

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soils damaged by the dustbowl years can still be found across the Western Central Great Plains. Most of these soils have lost top soil rich in organic matter. Our objective was to determine best management practices for remediating these soils using beef manure as an organic amendment. In a field ...

  2. In vivo rehardening of enamel eroded by a cola drink.

    PubMed

    Kim, J W; Jang, K T; Lee, S H; Kim, C C; Hahn, S H; García-Godoy, F

    2001-01-01

    There are many concerns about the erosive effects of acidic beverages. In this study, the effects of Pepsi-Cola (pH 2.41) on bovine enamel and the rehardening effect resulting from intraoral exposure of the teeth were determined by microhardness testing (Vicker's Hardness Number). Bovine enamel specimens (VHN 380.00 +/- 12.74) were immersed in 100 ml of Pepsi-Cola for five minutes and subsequently exposed to human intraoral environment through the use of a removable resin plate. Microhardness testing was performed on specimens after one hour, twenty-four hours and forty-eight hours of exposure to an intraoral environment. The microhardness value was significantly (p < 0.05) reduced by the cola beverage (VHN 262.13 +/- 20.34), and significantly (p < 0.05) increased after intraoral exposure for one hour (VHN 299.75 +/- 26.86) and twenty-four hours (VHN 328.00 +/- 18.70). The difference in the microhardness between the twenty-four-hour group and the forty-eight-hour group (VHN 333.50 +/- 15.13) was not significant (p > 0.05). The microhardness value of the forty-eight-hour group was significantly less than the values recorded during the initial pre-study measurements p < 0.05). PMID:11475687

  3. Academic Freedom Is Eroding in South Africa, Critics Say

    ERIC Educational Resources Information Center

    Lindow, Megan

    2007-01-01

    A spate of recent dismissals and disciplinary actions taken by South African universities against outspoken faculty members signals a broad erosion of academic freedom in higher education, academics and civil-society groups say. Much of the negative attention lately has focused on the University of KwaZulu-Natal, where academics say they face…

  4. Modeling an exhumed basin: A method for estimating eroded overburden

    USGS Publications Warehouse

    Poelchau, H.S.

    2001-01-01

    The Alberta Deep Basin in western Canada has undergone a large amount of erosion following deep burial in the Eocene. Basin modeling and simulation of burial and temperature history require estimates of maximum overburden for each gridpoint in the basin model. Erosion can be estimated using shale compaction trends. For instance, the widely used Magara method attempts to establish a sonic log gradient for shales and uses the extrapolation to a theoretical uncompacted shale value as a first indication of overcompaction and estimation of the amount of erosion. Because such gradients are difficult to establish in many wells, an extension of this method was devised to help map erosion over a large area. Sonic A; values of one suitable shale formation are calibrated with maximum depth of burial estimates from sonic log extrapolation for several wells. This resulting regression equation then can be used to estimate and map maximum depth of burial or amount of erosion for all wells in which this formation has been logged. The example from the Alberta Deep Basin shows that the magnitude of erosion calculated by this method is conservative and comparable to independent estimates using vitrinite reflectance gradient methods. ?? 2001 International Association for Mathematical Geology.

  5. Rip currents, mega-cusps, and eroding dunes

    USGS Publications Warehouse

    Thornton, E.B.; MacMahan, J.; Sallenger, A.H.

    2007-01-01

    Dune erosion is shown to occur at the embayment of beach mega-cusps O(200 m alongshore) that are associated with rip currents. The beach is the narrowest at the embayment of the mega-cusps allowing the swash of large storm waves coincident with high tides to reach the toe of the dune, to undercut the dune and to cause dune erosion. Field measurements of dune, beach, and rip current morphology are acquired along an 18 km shoreline in southern Monterey Bay, California. This section of the bay consists of a sandy shoreline backed by extensive dunes, rising to heights exceeding 40 m. There is a large increase in wave height going from small wave heights in the shadow of a headland, to the center of the bay where convergence of waves owing to refraction over the Monterey Bay submarine canyon results in larger wave heights. The large alongshore gradient in wave height results in a concomitant alongshore gradient in morphodynamic scale. The strongly refracted waves and narrow bay aperture result in near normal wave incidence, resulting in well-developed, persistent rip currents along the entire shoreline. The alongshore variations of the cuspate shoreline are found significantly correlated with the alongshore variations in rip spacing at 95% confidence. The alongshore variations of the volume of dune erosion are found significantly correlated with alongshore variations of the cuspate shoreline at 95% confidence. Therefore, it is concluded the mega-cusps are associated with rip currents and that the location of dune erosion is associated with the embayment of the mega-cusp.

  6. Biological effects of polychlorinated dibenzo-p-dioxins, dibenzofurans, and biphenyls in bald eagle (Haliaeetus leucocephalus) chicks

    SciTech Connect

    Elliott, J.E. |; Norstrom, R.J.; Lorenzen, A.; Kennedy, S.W.; Hart, L.E.; Bellward, G.D.; Cheng, K.M.; Philibert, H.; Stegeman, J.J.

    1996-05-01

    During the 1992 breeding season, eggs of bald eagles (Haliaeetus leucocephalus) were collected within a gradient of exposure to chlorinated hydrocarbon pollutants on the southern coast of British Columbia. Twenty-five eggs were placed in a laboratory incubator, of which 18 hatched; chicks were sacrificed within 24 h. Hatching success was not significantly different between eggs taken from pulp mill sites and reference sites. A hepatic cytochrome P4501A (CYP1A) cross-reactive protein was induced nearly sixfold in chicks from near a pulp mill at Powell River compared to those from a reference site. Hepatic ethoxyresorufin-O-deethylase (EROD) and benzyloxyresorufin O-dealkylase (BROD) activities were also significantly elevated in chicks from nests located near pulp mills compared to reference sites. A hepatic CYP2B cross-reactive protein was threefold higher in chicks from pulp mill versus reference sites, but the difference was not significant. Residual yolk sacs of eggs collected near pulp mill sites contained greater concentrations of 2,3,7,8-substituted polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) compared to reference areas. No significant differences in concentrations of polychlorinated biphenyls (PCBs), non-ortho congeners, and organochlorine pesticides occurred among sites. Regressions showed that the hepatic CYP1A cross-reactive protein and EROD and BROD activities were positively correlated with 2,3,7,8-TCDD, 2,3,7,8-TCDF, and toxic equivalents (TEQs{sub WHO}--World Health Organization toxic equivalence factors) in yolk sacs. No significant concentration-related effects were found for morphological, physiological, or histological parameters, such as chick growth, edema, or density of thymic lymphocytes. Using hepatic CYP1A induction as a biomarker, a no-observed-effect-level of 100 ng/kg and a lowest-observed-effect-level of 210 ng/kg TEQs{sub WHO} on a whole egg (wet weight basis) are suggested for bald eagle chicks.

  7. Reproduction of black-crowned night-herons related to predation and contaminants in Oregon and Washington, USA

    USGS Publications Warehouse

    Blus, L.J.; Rattner, B.A.; Melancon, M.J.; Henny, C.J.

    1997-01-01

    We studied reproductive characteristics of Black-crowned Night-Herons (Nycticorax nycticorax) at four colonies in south central Washington and one colony in north central Oregon in 1991. Nest success, adjusted using the Mayfield method, was significantly different between colonies and ranged from 12-84% to hatching and 12-73% to 14 days post-hatching. The mean number of young surviving to 14 days of age in each colony ranged from 0.47-1.94 per nesting female (includes recycling efforts that involve laying more than one clutch). They were marked intercolony differences in clutch size and incidence of recycling. Predation (primarily avian) was a major factor that adversely affected nest success in three colonies and was relatively unimportant in two colonies. Residues of DDE, total polychlorinated biphenyls, 2,3,7,8-tetrachlorodibenzo-p-dioxin, and other compounds in eggs were generally low and apparently had little influence on reproductive success at any of the colonies. Mean eggshell thinning ranged from 7-1 1 % in comparison to a pre-1947 norm for eggs measured in museum collections. Cytochrome P450 enzyme (EROD, PROD, and BROD) induction in livers of pipped embryos by colony ranged from low to average in comparison with other colonies throughout the U.S. Average EROD and BROD activities were highest at Sand Dune Island and were lowest at Potholes Reservoir which was designated the reference colony. In relation to our study of three of the five colonies in the early 1980s, residues of DDE and several related compounds appeared to decline, nest predation rates increased, and nest success decreased at all three colonies.

  8. Reproduction of Black-crowned Night-Herons related to predation and contaminants in Oregon and Washington, USA

    USGS Publications Warehouse

    Blus, L.J.; Rattner, B.A.; Melancon, M.J.; Henny, C.J.

    1997-01-01

    We studied reproductive characteristics of Black-crowned Night-Herons (Nycitcorax nycticorax) at 4 colonies in south central Washington and 1 colony in north central Oregon in 1991. Nest success, adjusted using the Mayfield method, was significantly different between colonies and ranged from 12-84% to hatching and 12-73% to 14 days post-hatching. The mean number of young surviving to 14 days of age in each colony ranged from 0.47-1.94 per nesting female (includes recycling efforts that involve laying more than 1 clutch). There were marked intercolony differences in clutch size and incidence of recycling. Predation (primarily avian) was a major factor that adversely affected nest success in 3 colonies and was relatively unimportant in 2 colonies. Residues of DDE, total polychlorinated biphenyls, 2,3,7,8-tetrachlorodibenzo-p-dioxin, and other compounds in eggs were generally low and apparently had little influence on reproductive success at any of the colonies. Mean eggshell thinning ranged from 7-11% in comparison to a pre-1947 norm for eggs measured in museum collections. Cytochrome P450 enzyme (EROD, PROD, and BROD) induction in livers of pipped embryos by colony ranged from low to average in comparison with other colonies throughout the U.S. Average EROD and BROD activities were highest at Sand Dune Island and were lowest at Potholes Reservoir which was designated the reference colony. In relation to our study of 3 of the 5 colonies in the early 1980s, residues of DDE and several related compounds appeared to decline, nest predation rates increased, and nest success decreased at all 3 colonies.

  9. Blarina brevicauda as a biological monitor of polychlorinated biphenyls: Evaluation of hepatic cytochrome p450 induction

    USGS Publications Warehouse

    Russell, J.S.; Halbrook, R.S.; Woolf, A.; French, J.B.; Melancon, M.J.

    2004-01-01

    We assessed the value of short-tailed shrews (Blarina brevicauda) as a possible biomonitor for polychlorinated biphenyl pollution through measurement of the induction of hepatic cytochrome P450 and associated enzyme activities. First, we checked the inducibility of four monooxygenases (benzyloxyresorufin-O-dealkylase [BROD], ethoxyresorufin-O-dealkylase [EROD], methoxyresorufin-O-dealkylase [MROD], and pentoxyresorufin-O-dealkylase [PROD]) by measuring the activity of these enzymes in hepatic microsomes prepared from shrews injected with $-naphthoflavone ($NF) or phenobarbital (PB), typical inducers of cytochrome P4501A (CYP1A) and CYP2B enzyme families, respectively. Enzyme activity was induced in shrews that received $NF but not in shrews that received PB; PROD was not induced by either exposure. Later, shrews were exposed to a mixture of polychlorinated biphenyls (PCBs) (Aroclor 1242:1254, in 1:2 ratio) at 0.6, 9.6, and 150 ppm in food, for 31 d. Induction in these shrews was measured by specific enzyme activity (BROD, EROD, and MROD) in hepatic microsomes, by western blotting of solubilized microsomes against antibodies to CYP1A or CYP2B, and by duration of sodium pentobarbital-induced sleep. These three CYP enzymes were induced in shrews by PCBs at similar levels of exposure as in cotton rat (Sigmodon hispidus). Neither sleep time nor the amount of CYP2B family protein were affected by PCB exposure. Blarina brevicauda can be a useful biomonitor of PCBs that induce CYP1A, especially in habitats where they are the abundant small mammal.

  10. Blarina brevicauda as a biological monitor of polychlorinated biphenyls: evaluation of hepatic cytochrome P450 induction.

    PubMed

    Russell, Julie S; Halbrook, Richard S; Woolf, Alan; French, John B; Melancon, Mark J

    2004-08-01

    We assessed the value of short-tailed shrews (Blarina brevicauda) as a possible biomonitor for polychlorinated biphenyl pollution through measurement of the induction of hepatic cytochrome P450 and associated enzyme activities. First, we checked the inducibility of four monooxygenases (benzyloxyresorufin-O-dealkylase [BROD], ethoxyresorufin-O-dealkylase [EROD], methoxyresorufin-O-dealkylase [MROD], and pentoxyresorufin-O-dealkylase [PROD]) by measuring the activity of these enzymes in hepatic microsomes prepared from shrews injected with beta-naphthoflavone (betaNF) or phenobarbital (PB), typical inducers of cytochrome P4501A (CYP1A) and CYP2B enzyme families, respectively. Enzyme activity was induced in shrews that received betaNF but not in shrews that received PB; PROD was not induced by either exposure. Later, shrews were exposed to a mixture of polychlorinated biphenyls (PCBs) (Aroclor 1242:1254, in 1:2 ratio) at 0.6, 9.6, and 150 ppm in food, for 31 d. Induction in these shrews was measured by specific enzyme activity (BROD, EROD, and MROD) in hepatic microsomes, by western blotting of solubilized microsomes against antibodies to CYP1A or CYP2B, and by duration of sodium pentobarbital-induced sleep. These three CYP enzymes were induced in shrews by PCBs at similar levels of exposure as in cotton rat (Sigmodon hispidus). Neither sleep time nor the amount of CYP2B family protein were affected by PCB exposure. Blarina brevicauda can be a useful biomonitor of PCBs that induce CYP1A, especially in habitats where they are the abundant small mammal. PMID:15352474

  11. The effect of aspartame on rat brain xenobiotic-metabolizing enzymes.

    PubMed

    Vences-Mejía, A; Labra-Ruíz, N; Hernández-Martínez, N; Dorado-González, V; Gómez-Garduño, J; Pérez-López, I; Nosti-Palacios, R; Camacho Carranza, R; Espinosa-Aguirre, J J

    2006-08-01

    This study demonstrates that chronic aspartame (ASP) consumption leads to an increase of phase I metabolizing enzymes (cytochrome P450 (CYP)) in rat brain. Wistar rats were treated by gavage with ASP at daily doses of 75 and 125 mg/kg body weight for 30 days. Cerebrum and cerebellum were used to obtain microsomal fractions to analyse activity and protein levels of seven cytochrome P450 enzymes. Increases in activity were consistently found with the 75 mg/kg dose both in cerebrum and cerebellum for all seven enzymes, although not at the same levels: CYP 2E1-associated 4-nitrophenol hydroxylase (4-NPH) activity was increased 1.5-fold in cerebrum and 25-fold in cerebellum; likewise, CYP2B1-associated penthoxyresorufin O-dealkylase (PROD) activity increased 2.9- and 1.7-fold respectively, CYP2B2-associated benzyloxyresorufin O-dealkylase (BROD) 4.5- and 1.1-fold, CYP3A-associated erythromycin N-demethylase (END) 1.4- and 3.3-fold, CYP1A1-associated ethoxyresorufin O-deethylase (EROD) 5.5- and 2.8-fold, and CYP1A2-associated methoxyresorufin O-demethylase (MROD) 3.7- and 1.3-fold. Furthermore, the pattern of induction of CYP immunoreactive proteins by ASP paralleled that of 4-NHP-, PROD-, BROD-, END-, EROD- and MROD-related activities only in the cerebellum. Conversely, no differences in CYP concentration and activity were detected in hepatic microsomes of treated animals with respect to the controls, suggesting a brain-specific response to ASP treatment.

  12. Cytochrome P450 1A expression in midwater fishes: Potential effects of chemical contaminants in remote oceanic zones

    USGS Publications Warehouse

    Stegeman, John J.; Schlezinger, J.J.; Craddock, J.E.; Tillitt, D.E.

    2001-01-01

    Cytochrome P450 1A (CYP1A) induction is a robust marker for exposure to polynuclear aromatic hydrocarbons and planar halogenated aromatic hydrocarbons that are aryl hydrocarbon receptor agonists. We examined CYP1A expression in mesopelagic fishes from the western North Atlantic. Individuals in 22 species were obtained from slope water and the Sargasso Sea in 1977, 1978, and 1993. Aryl hydrocarbon hydroxylase (AHH), a CYP1A activity, was detected in liver from all species in 1977/78. In some, including Gonostoma elongatum, AHH was inhibited by the CYP1A inhibitor ??-naphthoflavone. CYP1A-dependent ethoxyresorufin O-deethylase (EROD) was detected in liver microsomes of all species in 1993; rates were highest in G. elongatum and Argyropelecus aculeatus. Immunoblot analysis with the CYP1A-specific monoclonal antibody 1-12-3 detected a single microsomal protein band in most 1993 samples; the highest content was in G. elongatum. Immunohistochemical analysis showed CYP1A staining in gill, heart, kidney, and/or liver of several species. Extracts of the 1993 G. elongatum and A. aculeatus, when applied to fish hepatoma cells (PLHC-1) in culture, elicited a significant induction of EROD in those cells. The capacity of the extracts to induce CYP1A correlated with the content of PCBs measured in the same fish (2-4.6 ng/g total body weight). Mesopelagic fish in the western North Atlantic, which experience no direct exposure to surface waters or sediments, are exposed chronically to inducers of CYP1A at levels that appear to be biochemically active in those fish.Cytochrome P450 1A (CYP1A) induction is a robust marker for exposure to polynuclear aromatic hydrocarbons and planar halogenated aromatic hydrocarbons that are awl hydrocarbon receptor agonists. We examined CYP1A expression in mesopelagic fishes from the western North Atlantic. Individuals in 22 species were obtained from slope water and the Sargasso Sea in 1977, 1978, and 1993. Aryl hydrocarbon hydroxylase (AHH), a CYP1A

  13. Mink biomagnification factors for dioxin-like compounds fed Saginaw Bay carp

    SciTech Connect

    Kubiak, T.J.; Tillitt, D.E.; Heaton, S.N.; Bursian, S.N.; Giesy, J.P.; Render, J.A.; Aulerich, R.J.

    1994-12-31

    Diets containing 0, 10, 20 and 40% Saginaw Bay carp were fed to ranch mink to assess reproductive effects. All carp diets adversely affected reproduction. The diets and livers of the adult mink at the end of the study were chemically analyzed for planar halogenated hydrocarbons (PHHS) that induce aryl hydrocarbon hydroxylase (AHH)/ethoxyresorufin o-deethylase (EROD). Biomagnification factors (BMFS) from diets to mink livers were calculated. AHH and EROD-active PCB congeners uniformly magnified across diets except for PCB 126, which had higher magnification at lowest carp and control diets. PCB and PCDF congener magnification ranged from incalculable to 60-fold higher and individual PCDDs ranged from incalculable to 165 times the diet. As expected from previous mammalian studies, 2378-TCDD magnified over an order of magnitude more than 2378-TCDF but by 4 to 5-fold less than 23478-PCDF. Based on dioxin equivalents theory and TEFS, PCB 126 ranked first in the liver residues of 2378-TCDD equivalents followed by PCB 105, 23478-PCDF and 2378-TCDD. Magnification factors allow for interpretation of relative exposure risks from certain wild forage species if wild mink liver concentrations are known. Conversely, knowledge of wild mink forage item concentrations allows for calculation of an estimated wild mink liver residue, when the concentration and dietary forage percentage are multiplied by the BMF. Therefore, BMFs can assist in the elucidation of relative risk of a population to these contaminants without necessarily having large numbers of mink samples, especially in habitats such as the Saginaw Bay area where mink and otter populations are presumed to be affected by high PHH contamination.

  14. Polychlorinated biphenyls: correlation between in vivo and in vitro quantitative structure-activity relationships (QSARs)

    SciTech Connect

    Leece, B.; Denomme, M.A.; Towner, R.; Li, S.M.A.; Safe, S.

    1985-01-01

    The in vivo quantitative structure-activity relationships (QSARs) for several polychlorinated biphenyls (PCBs) were determined in the immature male Wistar rat. The ED25 and ED50 values for hepatic microsomal aryl hydrocarbon hydroxylase (AHH) and ethoxyresorufin O-deethylase (EROD) induction as well as for body weight loss and for thymic atrophy were determined for nine PCB congeners and 4'-bromo-2,3,4,5-tetrachlorobiphenyl. The most active compounds were the coplanar PCB congeners, 3,3',4,4',5-penta- and 3,3',4,4',5,5'-hexachlorobiphenyl; for example, their ED50 values for body weight loss were 3.25 and 15.1 ..mu..mol/kg, respectively. The in vivo toxicity of the coplanar PCB, 3,3',4,4'-tetrachlorobiphenyl, was significantly lower (ED50 for body weight loss = 730 ..mu..mol/kg) than the values observed for the more highly chlorinated homologs, and this was consistent with the more rapid metabolism of the lower chlorinated congener. The dose-response biologic and toxic effects of several mono-ortho-chloro-substituted analogs of the coplanar PCBs, including 2,3,4,4',5-, 2,3,3',4,4'-, 2',3,4,4',5- and 2,3',4,4',5-penta-, 2,3,3',4,4',5- and 2,3,3',4,4',5-hexachlorobiphenyl were also determined, and members of this group of compounds were all less toxic than 3,3',4,4',5-penta and 3,3',4,4',5,5'-hexachlorobiphenyl. There was a good rank order correlation between the in vivo QSAR data and the in vitro QSAR data and the in vitro QSARs for PCBs that were developed from their relative receptor binding affinities and potencies as inducers of AHH and EROD in rat hepatoma H-4-II E cells in culture.

  15. Enzymatic characterization of in vitro-expressed Baikal seal cytochrome P450 (CYP) 1A1, 1A2, and 1B1: implication of low metabolic potential of CYP1A2 uniquely evolved in aquatic mammals.

    PubMed

    Iwata, Hisato; Yamaguchi, Keisuke; Takeshita, Yoko; Kubota, Akira; Hirakawa, Shusaku; Isobe, Tomohiko; Hirano, Masashi; Kim, Eun-Young

    2015-05-01

    This study aimed to elucidate the catalytic function of cytochrome P450 (CYP) 1 enzymes in aquatic mammals. Alkoxyresorufin O-dealkylation (AROD) activities including methoxy- (MROD), ethoxy- (EROD), pentoxy- (PROD), and benzyloxyresorufin O-dealkylation (BROD), and 2- and 4-hydroxylation activities of 17β-estradiol (E2) were measured by using yeast-expressed Baikal seal (Pusa sibirica) CYP1A1, 1A2, and 1B1 proteins. Heterologous protein expression of the Baikal seal CYP1s (bsCYP1s) in yeast microsomes was confirmed by reduced CO-difference spectra and immunoblotting. Heterologously expressed human CYP1 enzyme (hCYP1) activities were simultaneously measured and compared with those of bsCYP1 isozymes. Recombinant bsCYP1A1 protein showed the highest Vmax of EROD, followed by MROD, PROD, and BROD, similar to that of hCYP1A1. Vmax/Km ratios of all AROD activities catalyzed by bsCYP1A1 were lower than those catalyzed by hCYP1A1, suggesting less potential for AROD by bsCYP1A1. Enzymatic assays for bsCYP1A2 showed no or minimal AROD activities, while hCYP1A2 displayed MROD and EROD activities. bsCYP1B1 showed an AROD profile (EROD>BROD>MROD>PROD) similar to that of hCYP1B1; however, Vmax/Km ratios of all AROD activities by bsCYP1B1 were higher. Yeast microsomes containing bsCYP1A1 and 1B1 and hCYP1A1, 1A2, and 1B1 metabolized E2 to 2-OHE2 and 4-OHE2, whereas bsCYP1A2 showed no such activity. Comparison of 4- and 2-hydroxylations of E2 by CYP1As suggests that bsCYP1A1, hCYP1A1, and 1A2 preferentially catalyze 2- rather than 4-hydroxylation. As for CYP1B1, the Vmax/Km ratios suggest that both Baikal seal and human CYPs catalyze 4- rather than 2-hydroxylation. Interspecies comparison showed that bsCYP1B1 has higher metabolic potencies for both E2 hydroxylations than does hCYP1B1, whereas the activity of bsCYP1A1 was lower than that of hCYP1A1. Messenger RNA expression levels of bsCYP1s in the liver of Baikal seals indicated that bsCYP1A1 and 1A2 enzymes contributed to 16

  16. Experimental investigation on axial-flow turbine arrays in erodible and non-erodible channels: Performance, flow-field, and bathymetric interactions

    NASA Astrophysics Data System (ADS)

    Hill, Craig; Sotiropoulos, Fotis; Guala, Michele

    2014-11-01

    Natural channels ideal for hydrokinetic turbine installations present complex environments containing asymmetric flow, regions of high shear and turbulent eddies that impact turbine performance. To understand the impacts caused by variable topography, baseline conditions in a laboratory flume are compared to turbine performance, flow characteristics, and channel topography measurements from two additional experiments with small-scale and large-scale bathymetric features. Both aligned and staggered multi-turbine configurations were investigated. Small-scale axial-flow rotors attached to miniature DC motors provided measurements of turbine performance and response to i) complex topographic features and ii) flow features induced by upstream turbines. Discussion will focus on optimal streamwise and lateral spacing for axial-flow devices, turbine-topography interactions within arrays and inter-array flow-field measurements. Primary focus will center on results from turbines separated by a streamwise distance of 7dT. Additionally, results indicate possible control strategies for turbines installed in complex natural environments. This work was supported by NSF PFI Grant IIP-1318201, CAREER: Geophysical Flow Control (NSF).

  17. In vitro cytotoxicity of polycyclic aromatic hydrocarbon residues arising through repeated fish fried oil in human hepatoma Hep G2 cell line.

    PubMed

    Pandey, Manoj K; Pant, Aditya B; Das, Mukul

    2006-04-01

    Repeated frying of vegetarian and non-vegetarian foods in edible oil is a common practice round the globe. Our studies suggest that repeated fish fried oil (RFFO) generates polycyclic aromatic hydrocarbons (PAHs), which may lead to hazardous effect on human health. In order to understand the mechanism of toxicity of RFFO extracts containing a mixture of PAHs, the in vitro cytotoxicity assays in human hepatoma cell line, Hep G2 was undertaken. In addition to RFFO extract, benzo(a)pyrene (BP) and chrysene were used as prototype compounds for heavy and light PAHs, respectively. Doses of BP and chrysene were made in such a way, that it could represent the appropriate content of heavy and light PAHs found in the RFFO extract. Out of total content of PAHs (1240.4 microg/kg) in RFFO, major composition is of light PAHs (854.8 microg/kg) while heavy PAHs showed the concentration of 385.7 microg/kg. Treatment of cells with 1 microg/ml RFFO extract for 48 h showed significant induction in ethoxyresorufin-O-deethylase (EROD) activity. Exposure of cells to higher doses of RFFO extract (10-100 microg/ml) for 24, 48 and 72 h caused 3.5-5.2, 4.3-8.5 and 1.8-2.3-fold enhancement in EROD activity, respectively. Further, RFFO extract caused a dose dependent increase (2.1-3.5-fold) in aryl hydrocarbon hydroxylase (AHH) activity at 48 h. Induction of EROD and AHH activity in Hep G2 cells was found to be relatively more following BP or chrysene treatment as compared to RFFO extract. RFFO extract did not cause any significant effect on cell viability at 1 microg/ml and 10 microg/ml. However, at 100 microg/ml concentration RFFO extract significantly decreased the cell viability at 24, 48 and 72 h. Exposure of 10 microg/ml RFFO extract reduced the colony forming ability (CFA) of Hep G2 cells with maximum decrease of 33.5% at 72 h. However, exposure of cells to RFFO extract at highest concentration of assay (100 microg/ml) reduced CFA (35-52%) at 24, 48 and 72 h. RFFO extract (1-100 microg

  18. Quantifying the growth of a rapidly eroding bedrock gorge using repeat terrestrial Lidar

    NASA Astrophysics Data System (ADS)

    Cook, K. L.

    2012-12-01

    The Da'an River Gorge in western Taiwan provides a unique opportunity to observe the formation and evolution of a natural bedrock gorge. The 1.2 km long and up to 20 m deep gorge has formed since 1999 in response to uplift of the riverbed during the Chi-Chi earthquake. The extremely rapid pace of erosion enables us to observe both downcutting and channel widening over short time periods. We have monitored the evolution of the gorge since 2009 using repeat RTK GPS surveys and terrestrial Lidar scans. GPS surveys of the channel profile are conducted frequently, with 24 surveys to date, while Lidar scans are conducted after major floods, or after 5-9 months without a flood, for a total of 8 scans to date. The Lidar data are most useful for recording erosion of channel walls, which is quite episodic and highly variable along the channel. By quantifying the distribution of wall erosion in space and time, we can improve our understanding of channel widening processes and of the development of the channel planform, particularly the growth of bends. During the summer of 2012, the Da'an catchment experienced two large storm events, a meiyu (plum rain) event on June 10-13 that brought 800 mm of rain, and a typhoon on August 1-3 that brought 650 mm of rain. The resulting floods had significant geomorphic effects on the Da'an gorge, including up to 10s of meters of erosion on some sections of the gorge walls. We quantify these changes using Lidar surveys conducted on June 7, July 3, and in mid-August. Channel wall collapses also occur in the absence of large floods, and we use scans from August 23, 2011 and June 7, 2012 to quantify erosion during a period that included a number of small floods, but no large ones. This allows us to compare the impact of 9 months of normal conditions to the impact of short-duration extreme events.Before June flood After June flood

  19. Paper-based microfluidics with an erodible polymeric bridge giving controlled release and timed flow shutoff.

    PubMed

    Jahanshahi-Anbuhi, Sana; Henry, Aleah; Leung, Vincent; Sicard, Clémence; Pennings, Kevin; Pelton, Robert; Brennan, John D; Filipe, Carlos D M

    2014-01-01

    Water soluble pullulan films were formatted into paper-based microfluidic devices, serving as a controlled time shutoff valve. The utility of the valve was demonstrated by a one-step, fully automatic implementation of a complex pesticide assay requiring timed, sequential exposure of an immobilized enzyme layer to separate liquid streams. Pullulan film dissolution and the capillary wicking of aqueous solutions through the device were measured and modeled providing valve design criteria. The films dissolve mainly by surface erosion, meaning the film thickness mainly controls the shutoff time. This method can also provide time-dependent sequential release of reagents without compromising the simplicity and low cost of paper-based devices.

  20. Management practices to improve soil quality and productivity of eroded soil

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The topsoil in the central Great Plains Region (CGPR) has lost its quality and productivity through wind and water erosion induced by tillage and poor soil management. Organic amendment such as manure is one of the management practices that can restore the quality and the productivity of degraded/er...

  1. NEARBY LAKE SEDIMENT QUALITY AND SEEDLING TREE SURVIVAL ON ERODED OILY WASTE/BRINE CONTAMINATED SOIL

    EPA Science Inventory

    An ecosystem restoration study is being conducted at an old oil production area in Northeast Oklahoma. Surface soil samples from areas impacted by discarded crude oil and brine wastes have been chemically characterized. Surface erosion has occurred in areas impacted by waste disc...

  2. Potential of surface-eroding poly(ethylene carbonate) for drug delivery to macrophages.

    PubMed

    Bohr, Adam; Water, Jorrit J; Wang, Yingya; Arnfast, Lærke; Beck-Broichsitter, Moritz

    2016-09-25

    Films composed of poly(ethylene carbonate) (PEC), a biodegradable polymer, were compared with poly(lactide-co-glycolide) (PLGA) films loaded with and without the tuberculosis drug rifampicin to study the characteristics and performance of PEC as a potential carrier for controlled drug delivery to macrophages. All drug-loaded PLGA and PEC films were amorphous indicating good miscibility of the drug in the polymers, even at high drug loading (up to 50wt.%). Polymer degradation studies showed that PLGA degraded slowly via bulk erosion while PEC degraded more rapidly and near-linearly via enzyme mediated surface erosion (by cholesterol esterase). Drug release studies performed with polymer films indicated a diffusion/erosion dependent delivery behavior for PLGA while an almost zero-order drug release profile was observed from PEC due to the controlled polymer degradation process. When exposed to polymer degradation products the murine macrophage cell line J774A.1 showed less susceptibility to PEC than to PLGA. However, when seeding the macrophages on PLGA and PEC films no relevant difference in cell proliferation/growth kinetics was observed. Overall, this study emphasizes that PEC is an attractive polymer for controlled drug release and could provide superior performance to PLGA for some drug delivery applications including the treatment of macrophage infections. PMID:27492019

  3. The spectre of ghostwriting: eroding public trust in physicians, clinical trial integrity and biomedical authorship.

    PubMed

    DeTora, L M

    2016-07-01

    The impact of medical ghostwriting, a violation of authorship ethics, remains unclear within the biomedical literature and among the public, potentially raising concerns about the integrity of the biomedical evidence base. Core texts in authorship and ghostwriting from the clinical literature and the 2010 Senate Minority Report on ghostwriting were reviewed as were uses of the term 'ghostwriting' in contemporary (2009-2011) and more recent (2015-2016) journalistic news coverage originally printed in English. Journalistic coverage oversimplified key concerns about ghostwriting identified by the medical community and the US government. More recent journalistic uses of the term 'ghostwriting' suggest confusion with topics such as financial disclosures or patient monitoring. Pharmaism in the medical literature, an expression of bias against pharmaceutical companies that casts doubt on the credibility of physicians and scientists, may be a source for confusion. The tendency for medical journal editors to discuss ghostwriting in the context of clinical trial transparency or data integrity is another possible source for misinterpretation via oversimplification. Journalistic descriptions of ghostwriting consistently downplay the critical reasoning abilities and competence of practising physicians and deflect attention away from patient concerns and back to pharmaceutical companies. Some uses of the term ghostwriting in news coverage may implicitly undercut belief in the competence of physicians, a troubling trend. Further work is needed to characterise the impact of ghostwriting in the medical literature and to reassure the public that their trust in medical practitioners is well placed. PMID:27354171

  4. Is Frost Cracking By Segregation Ice Growth One of the Mechanisms That Erode Bedrock River Margins?

    NASA Astrophysics Data System (ADS)

    Alden, L. L.; Sklar, L. S.

    2014-12-01

    Rivers cut vertically and laterally into bedrock. However, control on the width of bedrock rivers is an unsolved problem. In alpine settings, frost cracking is one of the mechanisms that break down bedrock. Segregation ice drives growth of ice lenses within rock masses. When the temperature of the rock is within the "frost cracking window" of -3 to -8 °C, ice lenses can attract liquid water. Expanding ice lenses can exert sufficient pressure to fracture the rock. We hypothesize that alpine rivers may promote segregation ice growth at the river margin by supplying water, but also may inhibit frost cracking by supplying heat. We find support for this hypothesis in data collected along the Tuolumne and Mokelumne rivers in the Sierra Nevada, California. A 1D heat flow model predicts that frost cracking should occur above 2325 masl in this area. To test for a river effect, we measured fracture density along the Tuolumne River at ~2600 masl, finding that density at the river margin is significantly greater than on adjacent hillslopes in the Cathedral Peak granodiorite. We then deployed data loggers on the Mokelumne River (at 2486 masl) over the winter of 2013/2014 to record water, surface and subsurface rock temperatures at varying depths and distances from the river. Temperatures within the frost cracking window were only recorded at a distance of ~5 m from the river, suggesting an insulating effect from the river and snow cover. Rock temperatures 1 m deep equilibrated at ~ 2 °C, significantly colder than predicted by the 1D model. Ongoing work includes terrestrial LIDAR scans to detect erosion of the river bank at the Mokelumne site, and development of a 2D heat flow model to predict subsurface rock temperatures for varying surface boundary conditions and channel morphology. We expect that further analysis will reveal systematic relationships between the surface boundary conditions and rock temperature at depth, enabling predictive modeling of frost cracking intensity at the river margin.

  5. Microbiology of Wind-eroded Sediments: Current Knowledge and Future Research Directions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Wind erosion is a threat to the sustainability and productivity of soils that takes place at local, regional, and global scales. Current estimates of cost of wind erosion have not included the costs associated with the loss of soil biodiversity and reduced ecosystem functions. Microorganisms carrie...

  6. "Planned Parenthood v. Clark County School District": First Amendment Rights in Public Schools Continue to Erode.

    ERIC Educational Resources Information Center

    Walden, John C.

    1990-01-01

    The Ninth Circuit Court of Appeals decision in "Planned Parenthood" supported school officials who refused to publish certain advertisements in school-sponsored newspapers. Contends that school officials' desire to avoid any possible controversy was the underlying motive for the decision to not publish the advertisement. (MLF)

  7. The Dras arc: two successive volcanic events on eroded oceanic crust

    NASA Astrophysics Data System (ADS)

    Reuber, Ingrid

    1989-04-01

    The Dras arc is recognized as a volcanic arc system in the western part of the Indus suture zone and it constitutes the link between the Ladakh batholith and the Kohistan arc. This study is based on detailed mapping of the area between Dras, Kargil and Sanku which revealed the following: (1) The ultramafics of Dras and Thasgam can be followed across the Suru Dras ridge and are not intrusive into the arc volcanics, but instead constitute the most probably oceanic substratum of these volcanics. (2) Successive volcanic events are distinguished: (a) Dras I is a variable volcaniclastic series rich in slates and carbonates, which can probably be assigned to the Albo-Cenomanian, as dated by orbitolines. This series is intruded by gabbro, diorite and granite and is deformed, essentially in the northern part. It is unconformably overlain by (b) the Dras II pyroclastics which grade southward into volcanic breccia and thus enable the location of the centres of volcanic activity during this younger period.

  8. Early Domain-Specific Knowledge? Nonlinear Developmental Trajectories Further Erode a House of Sand

    ERIC Educational Resources Information Center

    Deak, Gedeon O.

    2011-01-01

    Rakison and Yermolayeva (this issue) argue that domain specificity is difficult to reconcile with U-, N-, or M-shaped developmental trends. They are justified because: (1) There is no compelling evidence that nonlinear trends require mechanisms beyond general, well-known cognitive processes; and (2) epigenetic neuroscience provides no clear…

  9. Seasonal change of WEPP erodibility parameters for two fallow plots on a Palouse silt loam

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In cold regions, frozen soil can have a significant influence on runoff and water erosion. In the Inland Pacific Northwest U.S., major erosion events typically occur during winter as frozen soil thaws and exhibits low cohesion. The success of any erosion model used to select crop management systems ...

  10. Physical restoration of eroded soils in the Northern Great Plains (NA)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Management of agricultural lands often seeks to modify or control non-human environmental factors so as to support diverse (and often conflicting) objectives, such as extraction of resources, profitability, human survival, soil and water conservation, maintenance of wildlife habitat, food security, ...

  11. Tillage-induced CO2 loss across an eroded and restored landscape

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The increase of carbon dioxide in the atmosphere related to concerns about potential global warming and prospects of using soil as a sink for carbon has attracted interest. Recent studies involving tillage methods indicate major gaseous loss of carbon immediately after tillage. This presentation des...

  12. Restoration of eroded landscapes to reduce variability in soil properties affecting productivity

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In hilly landscapes, tillage and water erosion combine to induce large variability in soil productivity at the field scale. Approaches to manage this variability have been proposed, including restoring the landscape by physically moving soil from areas of net deposition to areas of net soil loss. We...

  13. Sampling network stratification by terrain classification in eroded agricultural landscapes at plot scale

    NASA Astrophysics Data System (ADS)

    Penížek, Vít; Zádorová, Tereza; Kodešová, Radka

    2015-04-01

    The description of soil properties variability is important aspect in land management and food production at plot scale. We describe novelty approach for design of sampling network on agricultural plots with high relief variability. The terrain properties were used for improved spatial prediction of soil properties including design of the sampling network. Regular sampling network, random sampling network, systematic unaligned sampling network and stratified sampling network schemes were compared to prove the advantages of relief based stratified sampling networks. The study was performed for humus horizon depth prediction on agriculture plot of 6.5 ha with dissected relief where originally homogenous soil cover was differentiated by erosion and sedimentation into mosaic of Chernozem, Regosol and colluvial soils. Moreover the comparison was done on three levels of sampling density (65, 40 and 24 sampling points). The stratification of sampling network was based on unsupervised relief classification. The performance of the soil properties prediction based on different sampling network was assesed by RMSE calculation based on predicted values versus validation dataset. According the RMSE, the stratified sampling network performed the best (7.4 cm) comparing the regular sampling network (10.8 cm), random sampling network (17.7 cm) and systematic unaligned sampling network (11.2 cm). The accuracy of the soil properties spatial prediction decreased with the decreasing number of sampling points, but the stratified network performed significantly better that other used methods. The study showed that, for soil properties spatial variability description at certain accuracy level, relief-based stratified network can contain 25 % less sampling points comparing to regular network. This leads to potential financial and person cost reduction for the soil survey. The study was supported by grant nr. 13-07516P of the Czech science foundation and by grant nr. QJ1230319 of the Ministry of Agriculture.

  14. The Chief Financial Officer's Perception of Financial Management Response to Eroding State Appropriations

    ERIC Educational Resources Information Center

    Tate, James Adam

    2012-01-01

    State fiscal support for public higher education is declining, particularly during recessionary periods. Public colleges and universities have limited channels of revenue and depend on state appropriations for current operating needs. There is an imperative now for public institutions to do more with less, be more efficient and effective in order…

  15. All Roads Lead to Rust: How Acculturation Erodes Latino Immigrant Trust in Government

    ERIC Educational Resources Information Center

    Michelson, Melissa R.

    2007-01-01

    Political trust is an important determinant of individual political behavior and government effectiveness and an indication of the health of civil society. Declining trust among Americans is well documented. Surveys of Latino immigrants indicate that they are also cynical about government, but it is not clear whether this distrust takes the same…

  16. Is Sovereign Immunity Archaic? Protections for Colleges and Universities Continue to Erode.

    ERIC Educational Resources Information Center

    Broadhurst, Arthur G.

    1996-01-01

    Public college and university administrators are concerned about steady erosion of immunities and tort caps traditionally relied upon for protection against lawsuits. In this context, institutions must consider their protection in these areas: extension of protection to all employees; scope of employment; nongovernmental functions; foundations and…

  17. Gypsum's influence on corn yield and p loss from an eroded southern piedmont soil

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Gypsum (CaSO4) has been shown to reduce dissolved P in surface water runoff from pastures fertilized with poultry litter (PL). However, limited research has evaluated gypsum’s influence on P loss under row crops. Moreover, can gypsum effectively reduce P loss when applied only to grass buffer strips...

  18. Composite vertical bite reconstructions in eroded dentitions after 5·5 years: a case series.

    PubMed

    Attin, T; Filli, T; Imfeld, C; Schmidlin, P R

    2012-01-01

    In the following case series, we report on six cases of erosive worn dentitions (75 posterior teeth), which have been reconstructed using a template-based technique with direct composite resin restorations and already examined after 3 years in service. In all patients either one or both tooth arches were completely restored using direct resin composite restorations. A wax-up-based template was used to avoid freehand build-up techniques and to ensure optimal anatomy and function. All patients were re-assessed after a mean service time of 5·5 years (mean 67 ± 4 months) using United States Public Health Service criteria. The overall quality of the restorations was good with predominantly 'alpha' and 'bravo' scores, respectively. However, the restorations showed some deterioration with respect to marginal quality, marginal discoloration, surface texture and anatomy as compared to the 3-year investigation. The marginal impairments could be resolved by polishing. It is concluded that this non-invasive technique provides a possible treatment option at least for the displayed observation period of 5·5 years.

  19. Transport of biologically important nutrients by wind in an eroding cold desert

    USGS Publications Warehouse

    Sankey, Joel B.; Germino, Matthew J.; Benner, Shawn G.; Glenn, Nancy F.; Hoover, Amber N.

    2012-01-01

    Wind erosion following fire is an important landscape process that can result in the redistribution of ecologically important soil resources. In this study we evaluated the potential for a fire patch in a desert shrubland to serve as a source of biologically important nutrients to the adjacent, downwind, unburned ecosystem. We analyzed nutrient concentrations (P, K, Ca, Mg, Cu, Fe, Mn, Al) in wind-transported sediments, and soils from burned and adjacent unburned surfaces, collected during the first to second growing seasons after a wildfire that burned in 2007 in Idaho, USA in sagebrush steppe; a type of cold desert shrubland. We also evaluated the timing of potential wind erosion events and weather conditions that might have contributed to nutrient availability in downwind shrubland. Findings indicated that post-fire wind erosion resulted in an important, but transient, addition of nutrients on the downwind shrubland. Aeolian sediments from the burned area were enriched relative to both the up- and down-wind soil and indicated the potential for a fertilization effect through the deposition of the nutrient-enriched sediment during the first, but not second, summer after wildfire. Weather conditions that could have produced nutrient transport events might have provided increased soil moisture necessary to make nutrients accessible for plants in the desert environment. Wind transport of nutrients following fire is likely important in the sagebrush steppe as it could contribute to pulses of resource availability that might, for example, affect plant species differently depending on their phenology, and nutrient- and water-use requirements.

  20. The effect of evaporation and nutrient enrichment on the erodability of mudflats in a mesotidal estuary

    NASA Astrophysics Data System (ADS)

    Fagherazzi, S.; Viggato, T.; Vieillard, A. M.; Fulweiler, R. W.

    2014-12-01

    The continental shelf region off the Washington-Oregon-California coast is seasonally exposed to water with a low aragonite saturation state by coastal upwelling of CO2-rich waters. To date, the spatial and temporal distribution of anthropogenic CO2 (Canth) contribution to the CO2-rich waters is largely unknown. Here we use an adaptation of the linear regression approach described in Feely et al. (2008) to utilize the GO-SHIP Repeat Hydrography data set from the northeast Pacific to establish an annually updated relationship between Canth and potential density. This relationship was then used with the NOAA Ocean Acidification Program West Coast cruise data sets from 2007, 2011, 2012 and 2013 to determine the spatial variations of Canth in the upwelled water. Our results show large spatial differences in Canth in surface waters along the coast with the lowest values (40-45 μmol kg-1) in strong upwelling regions of off northern California and southern Oregon and higher values (50-70 μmol kg-1) to the north and south of this region. Canth contributes an average of about 70 % of the increased amount of dissolved inorganic carbon in the upwelled waters at the surface relative to what would be expected from physical circulation and exchange with a preindustrial atmosphere alone. In contrast, Canth contributes an average of about 31%, and 16% of the increased amount of dissolved inorganic carbon at 50 m depth, and at 100 m depth respectively. The remaining contributions are either due to respiration processes in the water that was upwelled and transported to coastal regions or respiration processes that occurs locally during the course of the upwelling season. The uptake of Canth has caused the aragonite saturation horizon to shoal by approximately 30-50 m since preindustrial period so that the undersaturated waters are well within the regions of the continental shelf that affect the biological communities.

  1. Effect of Fluoride-Releasing Adhesive Systems on the Mechanical Properties of Eroded Dentin.

    PubMed

    Guedes, Ana Paula Albuquerque; Moda, Mariana Dias; Suzuki, Thaís Yumi Umeda; Godas, André Gustavo de Lima; Sundfeld, Renato Herman; Briso, André Luiz Fraga; Santos, Paulo Henrique dos

    2016-01-01

    The aim of the study was to evaluate the effect of erosive pH cycling with solutions that simulate dental erosion on Martens hardness (HMV) and elastic modulus (Eit) of dentin restored with fluoride-releasing adhesive systems. Twenty-seven bovine dentin slabs were restored with three adhesive systems: Adper Single Bond 2 total-etch adhesive system, One Up Bond F and Clearfil SE Protect fluoride-containing self-etching adhesive systems. The restorations were made with Filtek Z250. The HMV and Eit values at distances of 10, 30, 50 and 70 µm from the interface were evaluated using a dynamic ultra microhardness tester before and after immersion in deionized water, citric acid and hydrochloric acid (n=9). Data were submitted to repeated-measures ANOVA and Fisher's PLSD tests (=0.05). After erosive cycling, HMV values of dentin decreased in all groups. For dentin restored with Adper Single Bond 2, the lowest values were found closer to the hybrid layer, while for One Up Bond F and Clearfil SE Protect, the values remained unaltered at all distances. For dentin restored with fluoride-releasing adhesive systems, a decrease in Eit was found, but after 30 µm this difference was not significant. The acid substances were able to alter HMV and Eit of the underlying dentin. For fluoride-releasing adhesives, the greater the distance from bonded interface, the lower the Eit values. The fluoride in One Up Bond F and Clearfil SE Protect was able to protect the underlying dentin closer to the materials. In this way, the fluoride from adhesive systems could have some positive effect in the early stages of erosive lesions.

  2. Potential of surface-eroding poly(ethylene carbonate) for drug delivery to macrophages.

    PubMed

    Bohr, Adam; Water, Jorrit J; Wang, Yingya; Arnfast, Lærke; Beck-Broichsitter, Moritz

    2016-09-25

    Films composed of poly(ethylene carbonate) (PEC), a biodegradable polymer, were compared with poly(lactide-co-glycolide) (PLGA) films loaded with and without the tuberculosis drug rifampicin to study the characteristics and performance of PEC as a potential carrier for controlled drug delivery to macrophages. All drug-loaded PLGA and PEC films were amorphous indicating good miscibility of the drug in the polymers, even at high drug loading (up to 50wt.%). Polymer degradation studies showed that PLGA degraded slowly via bulk erosion while PEC degraded more rapidly and near-linearly via enzyme mediated surface erosion (by cholesterol esterase). Drug release studies performed with polymer films indicated a diffusion/erosion dependent delivery behavior for PLGA while an almost zero-order drug release profile was observed from PEC due to the controlled polymer degradation process. When exposed to polymer degradation products the murine macrophage cell line J774A.1 showed less susceptibility to PEC than to PLGA. However, when seeding the macrophages on PLGA and PEC films no relevant difference in cell proliferation/growth kinetics was observed. Overall, this study emphasizes that PEC is an attractive polymer for controlled drug release and could provide superior performance to PLGA for some drug delivery applications including the treatment of macrophage infections.

  3. Threat diversity will erode mammalian phylogenetic diversity in the near future.

    PubMed

    Jono, Clémentine M A; Pavoine, Sandrine

    2012-01-01

    To reduce the accelerating rate of phylogenetic diversity loss, many studies have searched for mechanisms that could explain why certain species are at risk, whereas others are not. In particular, it has been demonstrated that species might be affected by both extrinsic threat factors as well as intrinsic biological traits that could render a species more sensitive to extinction; here, we focus on extrinsic factors. Recently, the International Union for Conservation of Nature developed a new classification of threat types, including climate change, urbanization, pollution, agriculture and aquaculture, and harvesting/hunting. We have used this new classification to analyze two main factors that could explain the expected future loss of mammalian phylogenetic diversity: 1. differences in the type of threats that affect mammals and 2. differences in the number of major threats that accumulate for a single species. Our results showed that Cetartiodactyla, Diprotodontia, Monotremata, Perissodactyla, Primates, and Proboscidea could lose a high proportion of their current phylogenetic diversity in the coming decades. In contrast, Chiroptera, Didelphimorphia, and Rodentia could lose less phylogenetic diversity than expected if extinctions were random. Some mammalian clades, including Marsupiala, Chiroptera, and a subclade of Primates, are affected by particular threat types, most likely due solely to their geographic locations and associations with particular habitats. However, regardless of the geography, habitat, and taxon considered, it is not the threat type, but the threat diversity that determines the extinction risk for species and clades. Thus, some mammals might be randomly located in areas subjected to a large diversity of threats; they might also accumulate detrimental traits that render them sensitive to different threats, which is a characteristic that could be associated with large body size. Any action reducing threat diversity is expected to have a significant impact on future mammalian phylogeny.

  4. Comparative analysis of several sediment transport formulations applied to dam-break flows over erodible beds

    NASA Astrophysics Data System (ADS)

    Cea, Luis; Bladé, Ernest; Corestein, Georgina; Fraga, Ignacio; Espinal, Marc; Puertas, Jerónimo

    2014-05-01

    Transitory flows generated by dam failures have a great sediment transport capacity, which induces important morphological changes on the river topography. Several studies have been published regarding the coupling between the sediment transport and hydrodynamic equations in dam-break applications, in order to correctly model their mutual interaction. Most of these models solve the depth-averaged shallow water equations to compute the water depth and velocity. On the other hand, a wide variety of sediment transport formulations have been arbitrarily used to compute the topography evolution. These are based on semi-empirical equations which have been calibrated under stationary and uniform conditions very different from those achieved in dam-break flows. Soares-Frazao et al. (2012) proposed a Benchmark test consisting of a dam-break over a mobile bed, in which several teams of modellers participated using different numerical models, and concluded that the key issue which still needs to be investigated in morphological modelling of dam-break flows is the link between the solid transport and the hydrodynamic variables. This paper presents a comparative analysis of different sediment transport formulations applied to dam-break flows over mobile beds. All the formulations analysed are commonly used in morphological studies in rivers, and include the formulas of Meyer-Peter & Müller (1948), Wong-Parker (2003), Einstein-Brown (1950), van Rijn (1984), Engelund-Hansen (1967), Ackers-White (1973), Yang (1973), and a Meyer-Peter & Müller type formula but with ad-hoc coefficients. The relevance of corrections on the sediment flux direction and magnitude due to the bed slope and the non-equilibrium hypothesis is also analysed. All the formulations have been implemented in the numerical model Iber (Bladé et al. (2014)), which solves the depth-averaged shallow water equations coupled to the Exner equation to evaluate the bed evolution. Two different test cases have been studied. The first one is the benchmark case presented in Soares-Frazao et al. (2012), and consists in an instanteneous dam-break flow over a sand bed. The second one corresponds to the experimental studies performed at the Engineering Faculty of the UNAM (Fuentes-Mariles et al. (2010)) and consists in the erosion of a volcanic sand dike by an overtopping flow. In both cases experimental measurements of water depth and bed evolution are available to evaluate the performance of different sediment transport formulations. A sensitivity analysis to the physical properties of the bed material (grain density and size) is also presented for each formulation, in order to analyse to which degree the properties of the bed material need to be defined in the numerical model. References Bladé, E., Cea, L., Corestein, G., Escolano, E., Puertas, J., Vázquez-Cendón, M.E., Dolz, J., Coll, A. (2014). Iber: herramienta de simulación numérica del flujo en ríos. Revista Internacional de Métodos Numéricos para Cálculo y Diseño en Ingeniería, Vol.30(1), pp.1-10 Fuentes-Mariles, Ó. A., Cruz-Gerón, J. A., Rivera-Díaz, C., Luna-Cruz, F., and González-Prado, J. (2010). "Caracterización Experimental de Ruptura de Diques." XXIV Congreso Latinoamericano de Hidráulica Soares-Frazão et al. (2012). Dambreak flows over mobile beds: experiments and benchmark tests for numerical models. Journal of Hydraulic Research, Vol.50(4), pp.364-375

  5. Modification of Roberts' Theory for Rocket Exhaust Plumes Eroding Lunar Soil

    NASA Technical Reports Server (NTRS)

    Metzger, Philip T.; Lane, John E.; Immer, Christopher D.

    2008-01-01

    Roberts' model of lunar soil erosion beneath a landing rocket has been updated in several ways to predict the effects of future lunar landings. The model predicts, among other things, the number of divots that would result on surrounding hardware due to the impact of high velocity particulates, the amount and depth of surface material removed, the volume of ejected soil, its velocity, and the distance the particles travel on the Moon. The results are compared against measured results from the Apollo program and predictions are made for mitigating the spray around a future lunar outpost.

  6. From the Classroom to the Living Room: Eroding Academic Inequities through Home Visits

    ERIC Educational Resources Information Center

    Johnson, Eric J.

    2014-01-01

    This article illustrates the experiences of teachers who conducted home visits as a way to cultivate sustainable avenues of school-home communication with families from an immigrant and/or language-minority background. The data stemming from these experiences are used to outline a sociocultural approach to conducting home visits and strengthening…

  7. Magnetic anisotropy engineering: Single-crystalline Fe films on ion eroded ripple surfaces

    NASA Astrophysics Data System (ADS)

    Liedke, M. O.; Körner, M.; Lenz, K.; Grossmann, F.; Facsko, S.; Fassbender, J.

    2012-06-01

    We present a method to preselect the direction of an induced in-plane uniaxial magnetic anisotropy (UMA) in thin single-crystalline Fe films on MgO(001). Ion beam irradiation is used to modulate the MgO(001) surface with periodic ripples on the nanoscale. The ripple direction determines the orientation of the UMA, whereas the intrinsic cubic anisotropy of the Fe film is not affected. Thus, it is possible to superimpose an in-plane UMA with a precision of a few degrees—a level of control not reported so far that can be relevant for example in spintronics.

  8. Exploring the erodibility of sediments and harmful algal blooms in the Gulf of Maine

    USGS Publications Warehouse

    Butman, Bradford; Dickhudt, Patrick J.; Keafer, Bruce A.

    2012-01-01

    Investigators at the U.S. Geological Survey (USGS) are cooperating with scientists at Woods Hole Oceanographic Institution (WHOI) to investigate harmful algal blooms along the New England coast in the Gulf of Maine. These blooms are caused by cysts of the dinoflagellate Alexandrium fundyense that overwinter in the bottom sediments and germinate in spring. Depending on conditions such as temperature, light, nutrient levels, and currents, these single-celled organismscan create a bloom along the coast, called ‘red tides.’Shellfish that have ingested these cells in sufficient concentration can become toxic to humans and require that the shellfisheries be closed. After the spring bloom, the organisms form cysts that sink to the sea floor and are sequestered in the bottom sediments over the winter.

  9. HUBBLE SPACE TELESCOPE OPTICAL IMAGING OF THE ERODING DEBRIS DISK HD 61005

    SciTech Connect

    Maness, H. L.; Kalas, P.; Peek, K. M. G.; Chiang, E. I.; Graham, James R.; Scherer, K.; Fitzgerald, M. P.; Hines, D. C.; Schneider, G.; Metchev, S. A.

    2009-12-20

    We present Hubble Space Telescope optical coronagraphic polarization imaging observations of the dusty debris disk HD 61005. The scattered light intensity image and polarization structure reveal a highly inclined disk with a clear asymmetric, swept back component, suggestive of significant interaction with the ambient interstellar medium (ISM). The combination of our new data with the published 1.1 mum discovery image shows that the grains are blue scattering with no strong color gradient as a function of radius, implying predominantly submicron-sized grains. We investigate possible explanations that could account for the observed swept back, asymmetric morphology. Previous work has suggested that HD 61005 may be interacting with a cold, unusually dense interstellar cloud. However, limits on the intervening interstellar gas column density from an optical spectrum of HD 61005 in the Na I D lines render this possibility unlikely. Instead, HD 61005 may be embedded in a more typical warm, low-density cloud that introduces secular perturbations to dust grain orbits. This mechanism can significantly distort the ensemble disk structure within a typical cloud crossing time. For a counterintuitive relative flow direction-parallel to the disk midplane-we find that the structures generated by these distortions can very roughly approximate the HD 61005 morphology. Future observational studies constraining the direction of the relative ISM flow will thus provide an important constraint for future modeling. Independent of the interpretation for HD 61005, we expect that interstellar gas drag likely plays a role in producing asymmetries observed in other debris disk systems, such as HD 15115 and delta Velorum.

  10. Widespread horizontal genomic exchange does not erode species barriers among sympatric ducks

    PubMed Central

    2012-01-01

    Background The study of speciation and maintenance of species barriers is at the core of evolutionary biology. During speciation the genome of one population becomes separated from other populations of the same species, which may lead to genomic incompatibility with time. This separation is complete when no fertile offspring is produced from inter-population matings, which is the basis of the biological species concept. Birds, in particular ducks, are recognised as a challenging and illustrative group of higher vertebrates for speciation studies. There are many sympatric and ecologically similar duck species, among which fertile hybrids occur relatively frequently in nature, yet these species remain distinct. Results We show that the degree of shared single nucleotide polymorphisms (SNPs) between five species of dabbling ducks (genus Anas) is an order of magnitude higher than that previously reported between any pair of eukaryotic species with comparable evolutionary distances. We demonstrate that hybridisation has led to sustained exchange of genetic material between duck species on an evolutionary time scale without disintegrating species boundaries. Even though behavioural, genetic and ecological factors uphold species boundaries in ducks, we detect opposing forces allowing for viable interspecific hybrids, with long-term evolutionary implications. Based on the superspecies concept we here introduce the novel term "supra-population" to explain the persistence of SNPs identical by descent within the studied ducks despite their history as distinct species dating back millions of years. Conclusions By reviewing evidence from speciation theory, palaeogeography and palaeontology we propose a fundamentally new model of speciation to accommodate our genetic findings in dabbling ducks. This model, we argue, may also shed light on longstanding unresolved general speciation and hybridisation patterns in higher organisms, e.g. in other bird groups with unusually high hybridisation rates. Observed parallels to horizontal gene transfer in bacteria facilitate the understanding of why ducks have been such an evolutionarily successful group of animals. There is large evolutionary potential in the ability to exchange genes among species and the resulting dramatic increase of effective population size to counter selective constraints. PMID:22462721

  11. When Accountability Strategies Collide: Do Policy Changes That Raise Accountability Standards Also Erode Public Satisfaction?

    ERIC Educational Resources Information Center

    Jacobsen, Rebecca; Saultz, Andrew; Snyder, Jeffrey W.

    2013-01-01

    No Child Left Behind (NCLB) requires that two accountability strategies--raising standards and public pressure through publicizing performance data--be implemented simultaneously. However, when coupled, they may produce an inappropriate consequence for public opinion. The public may misunderstand the drop in achievement that occurs when the bar is…

  12. The doormat effect: when forgiving erodes self-respect and self-concept clarity.

    PubMed

    Luchies, Laura B; Finkel, Eli J; McNulty, James K; Kumashiro, Madoka

    2010-05-01

    We build on principles from interdependence theory and evolutionary psychology to propose that forgiving bolsters one's self-respect and self-concept clarity if the perpetrator has acted in a manner that signals that the victim will be safe and valued in a continued relationship with the perpetrator but that forgiving diminishes one's self-respect and self-concept clarity if the perpetrator has not. Study 1 employed a longitudinal design to demonstrate that the association of marital forgiveness with trajectories of self-respect over the first 5 years of marriage depends on the spouse's dispositional tendency to indicate that the partner will be safe and valued (i.e., agreeableness). Studies 2 and 3 employed experimental procedures to demonstrate that the effects of forgiveness on self-respect and self-concept clarity depend on the perpetrator's event-specific indication that the victim will be safe and valued (i.e., amends). Study 4 employed a longitudinal design to demonstrate that the association of forgiveness with subsequent self-respect and self-concept clarity similarly depends on the extent to which the perpetrator has made amends. These studies reveal that, under some circumstances, forgiveness negatively impacts the self.

  13. The High Cost "of" Convenience: Satisfying Short-Term Needs Erodes Long-Term Learning

    ERIC Educational Resources Information Center

    Zimmerman, Dian P.

    2015-01-01

    Novel ways of thinking often come from the cross-pollination of language from other professions. The term "satisficing" is one such term and is a powerful construct that fuses two concepts, satisfy and suffice, together to explain something new. Satisficing describes the often-paradoxical results that plague decision making. Depending on…

  14. Solute Transport in Eroded and Rehabilitated Prairie Landforms. 1. Nonreactive Solute

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cultivated North American prairie landscapes are often affected by soil erosion. Soil-landscape rehabilitation, in which topsoil is moved from areas of net deposition (lower slope) to areas of net soil loss by erosion (upper slope), can increase uniformity in soil properties across the landform and ...

  15. 7 CFR 12.21 - Identification of highly erodible lands criteria.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... the potential average annual rate of erosion for each soil by its predetermined soil loss tolerance (T) value. The T value represents the maximum annual rate of soil erosion that could occur without causing a... soil resists water erosion (K); and (iii) The function (LS), which includes the effects of slope...

  16. 7 CFR 12.21 - Identification of highly erodible lands criteria.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... the potential average annual rate of erosion for each soil by its predetermined soil loss tolerance (T) value. The T value represents the maximum annual rate of soil erosion that could occur without causing a... soil resists water erosion (K); and (iii) The function (LS), which includes the effects of slope...

  17. 7 CFR 12.21 - Identification of highly erodible lands criteria.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... the potential average annual rate of erosion for each soil by its predetermined soil loss tolerance (T) value. The T value represents the maximum annual rate of soil erosion that could occur without causing a... soil resists water erosion (K); and (iii) The function (LS), which includes the effects of slope...

  18. 7 CFR 12.21 - Identification of highly erodible lands criteria.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... the potential average annual rate of erosion for each soil by its predetermined soil loss tolerance (T) value. The T value represents the maximum annual rate of soil erosion that could occur without causing a... soil resists water erosion (K); and (iii) The function (LS), which includes the effects of slope...

  19. 75 FR 75961 - Notice of Implementation of the Wind Erosion Prediction System for Soil Erodibility System...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-12-07

    ... computer model that predicts soil erosion via simulation of the fundamental processes controlling wind erosion. WEPS can calculate soil movement, estimate plant damage, and predict PM-10 emissions when wind... Natural Resources Conservation Service Notice of Implementation of the Wind Erosion Prediction System...

  20. 7 CFR 12.21 - Identification of highly erodible lands criteria.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... the potential average annual rate of erosion for each soil by its predetermined soil loss tolerance (T) value. The T value represents the maximum annual rate of soil erosion that could occur without causing a... soil resists water erosion (K); and (iii) The function (LS), which includes the effects of slope...

  1. Persistence of soil organic matter in eroding versus depositional landform positions

    SciTech Connect

    Berhe, Asmeret A.; Harden, Jennifer W.; Torn, Margaret S.; Kleber, Markus; Burton, Sarah D.; Harte, John

    2012-06-02

    The terrestrial biosphere is dominated by sloping landscapes [Staub and Rosenzweig, 1986] where biogeochemical cycling of essential elements is controlled by interaction of geomorphic, pedogenic, and ecological processes that shape them. Recent studies have highlighted the important role of soil erosion in dynamics of soil organic matter (SOM) [Berhe et al., 2007, 2008; Boix-Fayos et al., 2009; Harden et al.,1999; Smith et al., 2001; Stallard, 1998a; Van Oost et al., 2007]. However, most process level studies of SOM cycling are dominantly located on nonsloping sites that experience minimal soil erosion and deposition and thus they fail to capture the influence of topography on SOM dynamics.

  2. Landform Evolution Modeling of Specific Fluvially Eroded Physiographic Units on Titan

    NASA Technical Reports Server (NTRS)

    Moore, J. M.; Howard, A. D.; Schenk, P. M.

    2015-01-01

    Several recent studies have proposed certain terrain types (i.e., physiographic units) on Titan thought to be formed by fluvial processes acting on local uplands of bedrock or in some cases sediment. We have earlier used our landform evolution models to make general comparisons between Titan and other ice world landscapes (principally those of the Galilean satellites) that we have modeled the action of fluvial processes. Here we give examples of specific landscapes that, subsequent to modeled fluvial work acting on the surfaces, produce landscapes which resemble mapped terrain types on Titan.

  3. Improved parameterization for the vertical flux of dust aerosols emitted by an eroding soil

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The representation of the dust cycle in atmospheric circulation models hinges on an accurate parameterization of the vertical dust flux at emission. However, existing parameterizations of the vertical dust flux vary substantially in their scaling with wind friction velocity, require input parameters...

  4. Costs of Nutrient Losses in Priceless Soils Eroded From the Highlands of Northwestern Ethiopia

    NASA Astrophysics Data System (ADS)

    Gebreselassie, Yihenew; Belay, Yihenew

    2014-05-01

    Soils formation is a geomorphic process that takes place through the interaction of soil forming factors in several hundreds and thousands of years. However, land degradation and soil erosion is consistently taking place in the horn of Africa washing away this priceless product in short period of time. The scale of the problem dramatically increased due to the increase in deforestation, overgrazing, over-cultivation, inappropriate farming practices, and increasing human population. Several research results were published in the region showing the extent of land degradation and soil loss. However, little attempt has been done to estimate the nutrient loss in monitory terms which made it difficult for policy makers to properly understand the extent of the problem. A study was, therefore, conducted in 2011 to estimate soil and nutrient losses caused by water erosion and predict nutrient replacement costs on different land use types and slope classes at Harfetay watershed, Northwestern Ethiopia. The revised soil loss equation (RUSLE) was used to estimate the soil loss from the different land uses and slope classes in watershed. Moreover, nutrient loss from similar units was calculated by multiplying the in situ nutrient concentration of soil samples by the estimated soil loss using RUSLE. The replacement costs of nutrient losses were calculated by multiplying the nutrient loss with the price of available nutrients in urea and diammonium phosphate. The estimate of the RUSLE indicated that the average soil losses in the study watershed were 119 tons ha-1 year-1 for non-conserved crop land, 23 tons for conserved farmlands, 23 tons for forest and shrub lands, 19 tons for grazing lands, and 6 tons for plantation forest. The mean soil loss for lower slope classes (<15%), middle slope classes (15-30%) and upper slope classes (>30%) were 30.11, 48.09 and 57.22 tons ha-1 year-1, respectively. The highest losses of total nitrogen (154.7 kg ha-1 year-1), available phosphorus (1.84 kg ha-1 year-1), and organic matter (1677.9 kg ha-1 year-1) were obtained from non-conserved cropland. Conversely, the lowest values of the same parameters were registered from the land covered with plantation forest. Comparing slope classes for non conserved cropland, organic matter and nutrient losses were higher in upper slope classes followed by middle and lower ones. The replacement cost of available N and available P for non-conserved cropland, conserved cropland, forest/shrub lands, grazing lands and plantations were 121, 36, 27, 32 and 13 Birr ha-1 year-1, respectively (1USD = 19 Birr); and the weighted mean replacement cost in the watershed was estimated to be 98 Birr ha-1 year-1 which is about 20% of the cost of fertilizer applied per individual farmers in the watershed. From the study it was possible to conclude that conversion of forest lands and plantation forests to cropland causes serious soil and nutrient losses. Construction of conservation structures on cropland, however, will reduce soil and nutrient losses. To halt soil and nutrient loss and ensure sustainable land management and agricultural development in the Harfetay watershed and similar watersheds, policy and development interventions including increasing awareness of farmers on of soil and nutrient losses, enforcing land use policies and expanding bio-physical soil conservation practices are required.

  5. Hydrodynamic effects of eroded materials on response of plasma-facing component during a tokamak disruption

    SciTech Connect

    Hassanein, A.; Konkashbaev, I.

    1999-10-25

    Loss of plasma confinement causes surface and structural damage to plasma-facing materials (PFMs) and remains a major obstacle for tokamak reactors. The deposited plasma energy results in surface erosion and structural failure. The surface erosion consists of vaporization, spallation, and liquid splatter of metallic materials, while the structural damage includes large temperature increases in structural materials and at the interfaces between surface coatings and structural members. Comprehensive models (contained in the HEIGHTS computer simulation package) are being used self-consistently to evaluate material damage. Splashing mechanisms occur as a result of volume bubble boiling and liquid hydrodynamic instabilities and brittle destruction mechanisms of nonmelting materials. The effect of macroscopic erosion on total mass losses and lifetime is evaluated. The macroscopic erosion products may further protect PFMs from severe erosion (via the droplet-shielding effect) in a manner similar to that of the vapor shielding concept.

  6. Soil depth mapping using seismic surface waves: Evaluation on eroded loess covered hillslopes

    NASA Astrophysics Data System (ADS)

    Bernardie, Severine; Samyn, Kevin; Cerdan, Olivier; Grandjean, Gilles

    2010-05-01

    The purposes of the multidisciplinary DIGISOIL project are the integration and improvement of in situ and proximal technologies for the assessment of soil properties and soil degradation indicators. Foreseen developments concern sensor technologies, data processing and their integration to applications of (digital) soil mapping (DSM). Among available techniques, the seismic one is, in this study, particularly tested for characterising soil vulnerability to erosion. The spectral analysis of surface waves (SASW) method is an in situ seismic technique used for evaluation of the stiffnesses (G) and associated depth in layered systems. A profile of Rayleigh wave velocity versus frequency, i.e., the dispersion curve, is calculated from each recorded seismogram before to be inverted to obtain the vertical profile of shear wave velocity Vs. Then, the soil stiffness can easily be calculated from the shear velocity if the material density is estimated, and the soil stiffness as a function of depth can be obtained. This last information can be a good indicator to identify the soil bedrock limit. SASW measurements adapted to soil characterisation is proposed in the DIGISOIL project, as it produces in an easy and quick way a 2D map of the soil. This system was tested for the digital mapping of the depth of loamy material in a catchment of the European loess belt. The validation of this methodology has been performed with the realisation of several acquisitions along the seismic profiles: - Several boreholes were drilled until the bedrock, permitting to get the geological features of the soil and the depth of the bedrock; - Several laboratory measurements of various parameters were done on samples taken from the boreholes at various depths, such as dry density, solid density, and water content; - Dynamic penetration tests were also conducted along the seismic profile, until the bedrock is attained. Some empirical correlations between the parameters measured with laboratory tests, the qc obtained from the dynamic penetration tests and the Vs acquired from the SASW measurements permit to assess the accuracy of the procedure and to evaluate its limitations. The depth to bedrock determined by this procedure can then be combined with the soil erosion susceptibility to produce a risk map. This methodology will help to target measures within areas that show a reduced soil depth associated with a high soil erosion susceptibility.

  7. Threat diversity will erode mammalian phylogenetic diversity in the near future.

    PubMed

    Jono, Clémentine M A; Pavoine, Sandrine

    2012-01-01

    To reduce the accelerating rate of phylogenetic diversity loss, many studies have searched for mechanisms that could explain why certain species are at risk, whereas others are not. In particular, it has been demonstrated that species might be affected by both extrinsic threat factors as well as intrinsic biological traits that could render a species more sensitive to extinction; here, we focus on extrinsic factors. Recently, the International Union for Conservation of Nature developed a new classification of threat types, including climate change, urbanization, pollution, agriculture and aquaculture, and harvesting/hunting. We have used this new classification to analyze two main factors that could explain the expected future loss of mammalian phylogenetic diversity: 1. differences in the type of threats that affect mammals and 2. differences in the number of major threats that accumulate for a single species. Our results showed that Cetartiodactyla, Diprotodontia, Monotremata, Perissodactyla, Primates, and Proboscidea could lose a high proportion of their current phylogenetic diversity in the coming decades. In contrast, Chiroptera, Didelphimorphia, and Rodentia could lose less phylogenetic diversity than expected if extinctions were random. Some mammalian clades, including Marsupiala, Chiroptera, and a subclade of Primates, are affected by particular threat types, most likely due solely to their geographic locations and associations with particular habitats. However, regardless of the geography, habitat, and taxon considered, it is not the threat type, but the threat diversity that determines the extinction risk for species and clades. Thus, some mammals might be randomly located in areas subjected to a large diversity of threats; they might also accumulate detrimental traits that render them sensitive to different threats, which is a characteristic that could be associated with large body size. Any action reducing threat diversity is expected to have a significant impact on future mammalian phylogeny. PMID:23029443

  8. Testing the Validity of Local Flux Laws in an Experimental Eroding Landscape

    NASA Astrophysics Data System (ADS)

    Sweeney, K. E.; Roering, J. J.; Ellis, C.

    2015-12-01

    Linking sediment transport to landscape evolution is fundamental to interpreting climate and tectonic signals from topography and sedimentary deposits. Most geomorphic process laws consist of simple continuum relationships between sediment flux and local topography. However, recent work has shown that nonlocal formulations, whereby sediment flux depends on upslope conditions, are more accurate descriptions of sediment motion, particularly in steep topography. Discriminating between local and nonlocal processes in natural landscapes is complicated by the scarcity of high-resolution topographic data and by the difficulty of measuring sediment flux. To test the validity of local formulations of sediment transport, we use an experimental erosive landscape that combines disturbance-driven, diffusive sediment transport and surface runoff. We conducted our experiments in the eXperimental Landscape Model at St. Anthony Falls Laboratory a 0.5 x 0.5 m test flume filled with crystalline silica (D50 = 30μ) mixed with water to increase cohesion and preclude surface infiltration. Topography is measured with a sheet laser scanner; total sediment flux is tracked with a series of load cells. We simulate uplift (relative baselevel fall) by dropping two parallel weirs at the edges of the experiment. Diffusive sediment transport in our experiments is driven by rainsplash from a constant head drip tank fitted with 625 blunt needles of fixed diameter; sediment is mobilized both through drop impact and the subsequent runoff of the drops. To drive advective transport, we produce surface runoff via a ring of misters that produce droplets that are too small to disturb the sediment surface on impact. Using the results from five experiments that systematically vary the time of drip box rainfall relative to misting rainfall, we calculate local erosion in our experiments by differencing successive time-slices of topography and test whether these patterns are related to local topographic metrics. By examining these patterns over different timescales, we are able to assess whether there is a signature of nonlocal transport in long-term topographic evolution or if, instead, local formulations are appropriate over timescales much greater than individual transport events.

  9. Effect of Fluoride-Releasing Adhesive Systems on the Mechanical Properties of Eroded Dentin.

    PubMed

    Guedes, Ana Paula Albuquerque; Moda, Mariana Dias; Suzuki, Thaís Yumi Umeda; Godas, André Gustavo de Lima; Sundfeld, Renato Herman; Briso, André Luiz Fraga; Santos, Paulo Henrique dos

    2016-01-01

    The aim of the study was to evaluate the effect of erosive pH cycling with solutions that simulate dental erosion on Martens hardness (HMV) and elastic modulus (Eit) of dentin restored with fluoride-releasing adhesive systems. Twenty-seven bovine dentin slabs were restored with three adhesive systems: Adper Single Bond 2 total-etch adhesive system, One Up Bond F and Clearfil SE Protect fluoride-containing self-etching adhesive systems. The restorations were made with Filtek Z250. The HMV and Eit values at distances of 10, 30, 50 and 70 µm from the interface were evaluated using a dynamic ultra microhardness tester before and after immersion in deionized water, citric acid and hydrochloric acid (n=9). Data were submitted to repeated-measures ANOVA and Fisher's PLSD tests (=0.05). After erosive cycling, HMV values of dentin decreased in all groups. For dentin restored with Adper Single Bond 2, the lowest values were found closer to the hybrid layer, while for One Up Bond F and Clearfil SE Protect, the values remained unaltered at all distances. For dentin restored with fluoride-releasing adhesive systems, a decrease in Eit was found, but after 30 µm this difference was not significant. The acid substances were able to alter HMV and Eit of the underlying dentin. For fluoride-releasing adhesives, the greater the distance from bonded interface, the lower the Eit values. The fluoride in One Up Bond F and Clearfil SE Protect was able to protect the underlying dentin closer to the materials. In this way, the fluoride from adhesive systems could have some positive effect in the early stages of erosive lesions. PMID:27058377

  10. Threat Diversity Will Erode Mammalian Phylogenetic Diversity in the Near Future

    PubMed Central

    Jono, Clémentine M. A.; Pavoine, Sandrine

    2012-01-01

    To reduce the accelerating rate of phylogenetic diversity loss, many studies have searched for mechanisms that could explain why certain species are at risk, whereas others are not. In particular, it has been demonstrated that species might be affected by both extrinsic threat factors as well as intrinsic biological traits that could render a species more sensitive to extinction; here, we focus on extrinsic factors. Recently, the International Union for Conservation of Nature developed a new classification of threat types, including climate change, urbanization, pollution, agriculture and aquaculture, and harvesting/hunting. We have used this new classification to analyze two main factors that could explain the expected future loss of mammalian phylogenetic diversity: 1. differences in the type of threats that affect mammals and 2. differences in the number of major threats that accumulate for a single species. Our results showed that Cetartiodactyla, Diprotodontia, Monotremata, Perissodactyla, Primates, and Proboscidea could lose a high proportion of their current phylogenetic diversity in the coming decades. In contrast, Chiroptera, Didelphimorphia, and Rodentia could lose less phylogenetic diversity than expected if extinctions were random. Some mammalian clades, including Marsupiala, Chiroptera, and a subclade of Primates, are affected by particular threat types, most likely due solely to their geographic locations and associations with particular habitats. However, regardless of the geography, habitat, and taxon considered, it is not the threat type, but the threat diversity that determines the extinction risk for species and clades. Thus, some mammals might be randomly located in areas subjected to a large diversity of threats; they might also accumulate detrimental traits that render them sensitive to different threats, which is a characteristic that could be associated with large body size. Any action reducing threat diversity is expected to have a significant impact on future mammalian phylogeny. PMID:23029443

  11. Surface eroding, liquid injectable polymers based on 5-ethylene ketal ε-caprolactone.

    PubMed

    Babasola, Oladunni Iyabo; Amsden, Brian G

    2011-10-10

    Liquid, injectable hydrophobic polymers are potentially useful as depot systems for localized drug delivery. Low molecular weight polymers of 5-ethylene ketal ε-caprolactone and copolymers of this monomer with D,L-lactide were prepared and their properties assessed with respect to their suitability for this purpose. The polymers were amorphous and of low viscosity, and the viscosity was adjustable by choice of initiator and/or by copolymerizing with D,L-lactide. Lower viscosity polymers were attained by using 350 Da methoxy poly(ethylene glycol) as an initiator in comparison to octan-1-ol, while copolymerization with D,L-lactide increased viscosity. The initiator used had no significant effect on the rate of mass loss in vitro, and copolymers with D,L-lactide (DLLA) degraded faster than 5-ethylene ketal ε-caprolactone (EKC) homopolymers. For the EKC-based polymers, a nearly constant degradation rate was observed. This finding was attributed to the hydrolytic susceptibility of the EKC-EKC ester linkage, which was comparable to that of DLLA-DLLA, coupled with a higher molecular weight of the water-soluble degradation product and the low initial molecular weight of the EKC-based polymers. Cytotoxicity of the hydrolyzed EKC monomer to 3T3 fibroblast cells was comparable to that of ε-caprolactone, suggesting that polymers prepared from EKC may be well tolerated upon in vivo implantation. PMID:21902176

  12. Two friends with eroded nodules on the ears: atypical fibroxanthoma case report.

    PubMed

    Pesapane, Filippo; Nazzaro, Gianluca; Lunardon, Luisa; Coggi, Antonella; Gianotti, Raffaele

    2015-01-01

    Atypical fibroxanthoma is an uncommon mesenchymal tumor that manifests clinically as a reddish papule or nodule in sun-exposed areas of the body. The clinical presentation is not specific and histology and immunohistochemistry are both necessary for a correct diagnosis. Surgery is the gold standard of therapy. Recurrence and metastasis should be excluded with a follow-up at 6 months, since this tumor should nowadays be considered a medium-grade neoplasm, rather than low-grade as previously believed. We report the case of two friends who came to our hospital during the same period, complaining of very similar lesions. After biopsy and immunohistochemical examination, a diagnosis of atypical fibroxanthoma in both cases was formulated. PMID:26375231

  13. Higher Education Gains for African Americans Erode Following Dismissal of "Adams," Observers Say.

    ERIC Educational Resources Information Center

    Barnes, Esmeralda

    1993-01-01

    Since a federal appeals court dropped a case 3 years ago, ruling that states, not the federal government, are responsible for ensuring equal educational opportunity, educators feel African-American education has lost ground. The case argued states sanctioned dual systems of education. States' elimination of some programs now threatens…

  14. Rapid host switching in generalist Campylobacter strains erodes the signal for tracing human infections.

    PubMed

    Dearlove, Bethany L; Cody, Alison J; Pascoe, Ben; Méric, Guillaume; Wilson, Daniel J; Sheppard, Samuel K

    2016-03-01

    Campylobacter jejuni and Campylobacter coli are the biggest causes of bacterial gastroenteritis in the developed world, with human infections typically arising from zoonotic transmission associated with infected meat. Because Campylobacter is not thought to survive well outside the gut, host-associated populations are genetically isolated to varying degrees. Therefore, the likely origin of most strains can be determined by host-associated variation in the genome. This is instructive for characterizing the source of human infection. However, some common strains, notably isolates belonging to the ST-21, ST-45 and ST-828 clonal complexes, appear to have broad host ranges, hindering source attribution. Here whole-genome sequencing has the potential to reveal fine-scale genetic structure associated with host specificity. We found that rates of zoonotic transmission among animal host species in these clonal complexes were so high that the signal of host association is all but obliterated, estimating one zoonotic transmission event every 1.6, 1.8 and 12 years in the ST-21, ST-45 and ST828 complexes, respectively. We attributed 89% of clinical cases to a chicken source, 10% to cattle and 1% to pig. Our results reveal that common strains of C. jejuni and C. coli infectious to humans are adapted to a generalist lifestyle, permitting rapid transmission between different hosts. Furthermore, they show that the weak signal of host association within these complexes presents a challenge for pinpointing the source of clinical infections, underlining the view that whole-genome sequencing, powerful though it is, cannot substitute for intensive sampling of suspected transmission reservoirs.

  15. 77 FR 74167 - Information Collection Request: Highly Erodible Land Conservation and Wetland Conservation

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-12-13

    ... information is collected in support of the conservation compliance provisions of Title XII of the Food Security Act of 1985 (the 1985 Farm Bill), as amended by the Food, Conservation, and Energy Act of 2008... Security Act of 1985 (16 U.S.C. 3801-3862), as amended by the Food, Conservation, and Energy Act of...

  16. Health insurance eroding for working families: employer-provided coverage declines for fifth consecutive year.

    PubMed

    Gould, Elise

    2007-01-01

    In 2005, the percentage of Americans with employer-provided health insurance fell for the fifth year in a row. Workers and their families have been falling into the ranks of the uninsured at alarming rates. The downward trend in employer-provided coverage for children also continued into 2005. In the previous four years, children were less likely to become uninsured as public sector health coverage expanded, but in 2005 the rate of uninsured children increased. While Medicaid and SCHIP still work for many, the government has not picked up coverage for everybody who lost insurance. The weakening of this system-notably for children-is particularly difficult for workers and their families in a time of stagnating incomes. Furthermore, these programs are not designed to prevent low-income adults or middle- or high-income families from becoming uninsured. Government at the federal and state levels has responded to medical inflation with policy changes that reduce public insurance eligibility or with proposals to reduce government costs. Federal policy proposals to lessen the tax advantage of workplace insurance or to encourage a private purchase system could further destabilize the employer-provided system. Now is a critical time to consider health insurance reform. Several promising solutions could increase access to affordable health care. The key is to create large, varied, and stable risk pools.

  17. Bioindicator beetles and plants in desertified and eroded lands in Turkey

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Xerophilous vegetation with characteristic insect assemblages is described in main agricultural regions and native landscapes of Turkey. Long term, intensive investigations documented vast biotic degradation of soil and vegetation (commonly referred to as desertification) by an overgrazing, construc...

  18. Evaluating soil erodibility dynamics to improve estimates of wind erosion in drylands

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Wind erosion is a key driver of land degradation in the world’s drylands. Soil loss and nutrient decline due to wind erosion increase the sensitivity of drylands to climate stressors. Better understanding the factors controlling wind erosion in drylands will provide a basis for identifying and testi...

  19. Rifts of deeply eroded Hawaiian basaltic shields: A structural analog for large Martian volcanoes

    NASA Technical Reports Server (NTRS)

    Knight, Michael D.; Walker, G. P. L.; Mouginis-Mark, P. J.; Rowland, Scott K.

    1988-01-01

    Recently derived morphologic evidence suggests that intrusive events have not only influenced the growth of young shield volcanoes on Mars but also the distribution of volatiles surrounding these volcanoes: in addition to rift zones and flank eruptions on Arsia Mons and Pavonis Mons, melt water channels were identified to the northwest of Hecates Tholus, to the south of Hadriaca Patera, and to the SE of Olympus Mons. Melt water release could be the surface expression of tectonic deformation of the region or, potentially, intrusive events associated with dike emplacement from each of these volcanoes. In this study the structural properties of Hawaiian shield volcanoes were studied where subaerial erosion has removed a sufficient amount of the surface to enable a direct investigation of the internal structure of the volcanoes. The field investigation of dike morphology and magma flow characteristics for several volcanoes in Hawaii is reported. A comprehensive investigation was made of the Koolau dike complex that passes through the summit caldera. A study of two other dissected Hawaiian volcanoes, namely Waianae and East Molokai, was commenced. The goal is not only to understand the emplacement process and magma flow within these terrestrial dikes, but also to explore the possible role that intrusive events may have played in volcano growth and the distribution of melt water release on Mars.

  20. Laboratory measurements of acoustic, electrical resistivity, and erodibility of soils as a function of compaction

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Catastrophic floods resulting from the failure of dam and levee infrastructures can paralyze the economy and social life of large populations for long periods of time. The United States has over 100,000 miles of levees and the National Inventory of Dams lists approximately 79,000 U.S. dams. The de...

  1. Morphology of an aluminum alloy eroded by a jet of angular particles impinging at normal incidence

    NASA Technical Reports Server (NTRS)

    Rao, P. V.; Young, S. G.; Buckley, D. H.

    1983-01-01

    The erosion of an aluminum alloy impinged by crushed glass particles at normal incidence was studied. The erosion patterns were analyzed by scanning electron microscopy, energy dispersive X-ray spectroscopy, and surface profilometer measurements. From the analysis of specimens tested at various driving gas pressures and time intervals, four distinct erosion regions were identified. A study of pit morphology and its relationship to cumulative erosion was made. Cutting wear is believed to be the predominant material removal mechanism; some evidence of deformation wear was found during the incubation period.

  2. Composite vertical bite reconstructions in eroded dentitions after 5·5 years: a case series.

    PubMed

    Attin, T; Filli, T; Imfeld, C; Schmidlin, P R

    2012-01-01

    In the following case series, we report on six cases of erosive worn dentitions (75 posterior teeth), which have been reconstructed using a template-based technique with direct composite resin restorations and already examined after 3 years in service. In all patients either one or both tooth arches were completely restored using direct resin composite restorations. A wax-up-based template was used to avoid freehand build-up techniques and to ensure optimal anatomy and function. All patients were re-assessed after a mean service time of 5·5 years (mean 67 ± 4 months) using United States Public Health Service criteria. The overall quality of the restorations was good with predominantly 'alpha' and 'bravo' scores, respectively. However, the restorations showed some deterioration with respect to marginal quality, marginal discoloration, surface texture and anatomy as compared to the 3-year investigation. The marginal impairments could be resolved by polishing. It is concluded that this non-invasive technique provides a possible treatment option at least for the displayed observation period of 5·5 years. PMID:21827523

  3. Inequity in Illinois: How Illogical School Funding Has Eroded Public Education. Special Report

    ERIC Educational Resources Information Center

    People For the American Way, 2004

    2004-01-01

    While there are many factors that determine the quality of a public school, inequitable and insufficient school funding is a major obstacle to improving public education for all children. When it comes to funding public education, Illinois has a serious problem. Not only does the state limit its commitment to adequately fund public schools, but it…

  4. Limiting Learning: How School Funding Caps Erode the Quality of Education. Briefing Paper

    ERIC Educational Resources Information Center

    Wial, Howard

    2004-01-01

    The Pennsylvania legislature is considering a school finance proposal, exemplified by House Bill 113 of the 2003 legislative session, that would shift some school funding away from local property taxes and toward state funds and local income taxes. The proposal would give greater proportional benefits to homeowners with lower property values. A…

  5. Erectile Dysfunction Drugs Changed the Protein Expressions and Activities of Drug-Metabolising Enzymes in the Liver of Male Rats

    PubMed Central

    Hassan, Mostafa

    2016-01-01

    Erectile dysfunction (ED) is a major health problem and is mainly associated with the persistent inability of men to maintain sufficient erection for satisfactory sexual performance. Millions of men are using sildenafil, vardenafil, and/or tadalafil for ED treatment. Cytochrome P450s (CYPs) play a central role in the metabolism of a wide range of xenobiotics as well as endogenous compounds. Susceptibility of individuals to the adverse effects of different drugs is mainly dependent on the expression of CYPs proteins. Therefore, changes in activities of phase I drug-metabolising enzymes [arylhydrocarbon hydroxylase (AHH), dimethylnitrosamine N-demethylase (DMN-dI), 7-ethoxycoumarin-O-deethylase (ECOD), and ethoxyresorufin-O-deethylase ((EROD)] and the protein expression of different CYPs isozymes (CYP1A2, CYP2E1, CYP2B1/2, CYP3A4, CYP2C23, and CYP2C6) were determined after treatment of male rats with either low or high doses of sildenafil (Viagra), tadalafil (Cialis), and/or vardenafil (Levitra) for 3 weeks. The present study showed that low doses of tadalafil and vardenafil increased DMN-dI activity by 32 and 23%, respectively. On the other hand, high doses of tadalafil, vardenafil, and sildenafil decreased such activity by 50, 56, and 52%, respectively. In addition, low doses of tadalafil and vardenafil induced the protein expression of CYP2E1. On the other hand, high doses of either tadalafil or sildenafil were more potent inhibitors to CYP2E1 expression than vardenafil. Moreover, low doses of both vardenafil and sildenafil markedly increased AHH activity by 162 and 247%, respectively, whereas high doses of tadalafil, vardenafil, and sildenafil inhibited such activity by 36, 49, and 57% and inhibited the EROD activity by 39, 49, and 33%, respectively. Low and high doses of tadalafil, vardenafil, and sildenafil inhibited the activity of NADPH-cytochrome c reductase as well as its protein expression. In addition, such drugs inhibited the expression of CYP B1/2 along

  6. Dioxin effects on wood duck (Aix sponsa) embryos from sites near paper mills

    SciTech Connect

    Beeman, D.K.; Melancon, M.J.; Fleming, W.J.

    1994-12-31

    Biological and biochemical variables were studied in wood duck embryos from four dioxin-contaminated sites near paper mills in the Southeastern United States and three reference sites. Sites were selected based on a history of dioxin contamination in both sediments and fish. In addition, wood duck embryos collected downstream from an Arkansas Superfund site with demonstrated dioxin-induced reproductive impairment served as positive controls. Whole clutches of eggs were collected from the wild after fifteen days of incubation and mechanically incubated. Two embryos per clutch were sacrificed at pipping and liver monooxygenase activities (BROD, EROD and MROD) were quantified. Hatching success was determined for the remainder of the nest. Preliminary results indicate no difference in monooxygenase activities across sites even though the authors have previously demonstrated induction of monooxygenase activity in wood duck embryos in laboratory studies. In addition, there were no differences in weight at pipping, liver weight and liver weight to body weight ratios. No differences were seen in hatching success or weight at hatch nor were there any gross morphological abnormalities. This may indicate that exposure of wood ducks nesting near these pulp paper mills is below those which cause elevated monooxygenase activities and reproductive impairment.

  7. Reproduction of black-crowned night-herons related to predation and contaminants

    USGS Publications Warehouse

    Blus, L.J.; Rattner, B.A.; Melancon, M.J.; Henny, C.J.

    1996-01-01

    Reproductive characteristics were studied at five colonies of Black-crowned Night-Herons (Nycticorax nycticorax) in south central Washington (4) and north central Oregon (1) in 1991. Predation (primarily avian) was a major factor that adversely affected reproductive success in three colonies and was relatively unimportant in two colonies. The mean number of young surviving to 14 days of age in each colony ranged from 0.47 to 1.94 per nesting female (includes recycling efforts). Unadjusted nest success at each I colony ranged from 31 to 84% (including recycling efforts). Clutch size and incidence of recycling also varied markedly by colony. Residues of DDE, total PCBs, and related compounds were relatively low in most eggs, and mean eggshell thinning by colony ranged from 7 to 11 %. Cytochrome P-450 enzyme (EROD, PROD, and BROD) induction in livers of pipped embryos by colony ranged from low to average in comparison with other colonies throughout the U.S. Residues of dioxins (TCDD) and furans (TCDF) in eggs were generally low and apparently had little influence on reproductive success at any of the colonies.

  8. Immunological and physiological effects of chronic exposure of Peromyscus leucopus to Aroclor 1254 at a concentration similar to that found at contaminated sites

    USGS Publications Warehouse

    Segre, M.; Arena, S.M.; Greeley, E.H.; Melancon, M.J.; Graham, D.A.; French, J.B.

    2002-01-01

    Polychlorinated biphenyls (PCBs) are environmental contaminants known to cause adverse health effects to biological systems. Limited data are available on their effects on the immune system of wildlife species. Previously, we found that 4 and 6-week-old white-footed mice (Peromyscus leucopus) born from dams injected with a single dose (300 mg/kg) of Aroclor 1254, had altered immunological, hematological, and biochemical responses. Here, we examined the effect of transplacental lactational and postnatal exposure to Aroclor 1254, at a concentration similar to that found at contaminated sites, on various physiological parameters of 22-week-old white-footed mice. Liver weight and liver somatic index of PCB treated animals were significantly higher, the combined weights of the adrenal glands were significantly lower and EROD and BROD enzyme activity was significantly higher compared to control values. The number of thymocytes of the treated mice was significantly lower than that of the controls; however, thymocytes of treated mice had a higher proliferative response to the mitogen Con A. These alterations were correlated with the PCBs body burdens. Some toxic effects of chronic exposure to PCBs, at levels comparable to exposure found in contaminated sites in the USA, are still evident in adult P. leucopus.

  9. Toxic effects upon exposure to polycyclic aromatic hydrocarbon (chrysene) in scallop Chlamys farreri during the reproduction period.

    PubMed

    Xiu, Meng; Pan, Luqing; Jin, Qian

    2016-06-01

    This study aims to investigate potential toxic effects of chrysene (CHR) on mature scallop Chlamys farreri during the reproduction period, using indicators of antioxidant defences and oxidative stress. Scallops were exposed to 0.2, 0.8 and 3.2μg/L waterborne CHR for 21 days, at day 10 scallops were induced to spawn. At days 1, 3, 6, 10, 11, 15 and 21, aryl hydrocarbon hydroxylase (AHH), 7-ethoxyresorufin-O-deethylase (EROD), glutathione-s-transferase (GST), glutathione (GSH), superoxide dismutase (SOD), lipid peroxidation (LPO), protein carbonyl (PC) and DNA strand breaks in digestive glands were examined by separately analysing male and female scallops. During the pre-spawn period, Levels of enzymatic activities and oxidative stress were all induced by the exposure to CHR for females and males. GST activity presented a good time- and dose-dependent relationship only in males, and GSH content showed a dose-dependent manner in both sexes. During the post-spawn period, different trends were observed, while PC contents maintained growth in time- and dose-dependent manner. Overall, males were more sensitive than females to CHR exposure in enzyme activities, and correspondingly, females suffered from more serious oxidative damages. Both GSH and PC contents seemed to be potential biomarkers for PAH exposure. These results will offer the information on toxicity of CHR in this species, and ensure the influence of gender and reproductive status on PAH detoxification metabolism.

  10. The detoxification process, bioaccumulation and damage effect in juvenile white shrimp Litopenaeus vannamei exposed to chrysene.

    PubMed

    Ren, Xianyun; Pan, Luqing; Wang, Lin

    2015-04-01

    This study aimed to evaluate the effect of chrysene (CHR) on detoxification enzymes, bioaccumulation and effect of CHR on biomolecule damage in different organs of the juvenile white shrimp Litopenaeus vannamei. In this study, juvenile white shrimp L. vannamei were exposed to CHR for 21 days at four different concentrations as 0, 0.3, 2.1 and 14.7 μg/L. Results showed that CHR bioaccumulation increased rapidly at first then reached a plateau. The activities of aryl hydrocarbon hydroxylase (AHH), 7-ethoxyresorufin O-deethylase (EROD), epoxide hydrolase (EH), glutathione-S-transferase (GST), sulfotransferase (SULT) and uridinediphosphate glucuronyltransferase (UGT) were induced and then became stable gradually. Moreover, 2.1 and 14.7 μg/L CHR treatments increased activity of superoxide dismutase (SOD) in gills and hepatopancreas, while total antioxidant capacity (T-AOC) and GSH/GSSG were suppressed after CHR exposure. Additionally, lipid peroxidation (LPO) levels, protein carbonyl (PC) contents and DNA damage were induced throughout the exposure period, and different trends were detected with time of exposure. Overall, these novel findings of CHR bioaccumulation and resulted toxicity demonstrate that CHR could affect the physical status of L. vannamei. This study will form a solid basis for a realistic extrapolation scientific data for aquaculture water monitoring and food security.

  11. Novel approaches to the use of cytochrome P450 activities in wildlife toxicity studies

    SciTech Connect

    VandenBerg, M.; Bosveld, A.T.C.

    1995-12-31

    Many wildlife toxicity studies, e.g. with avian species, use cytochrome P450 activities as markers for biological activities of environmental contaminants. It has been established that induction of CYP1A1 correlates with Ah-receptor mediated toxicity of dioxin-like compounds in many species. In addition, CYP1A1 plays a significant role in bioactivation of polycyclic aromatics. So far very few studies focused on the natural function of P450 isoenzymes in wildlife species. Besides classical hepatic CYP1A(1) associated activities, like EROD and AHH, several new techniques are available to study the activities of various CYP isoenzymes. Caffeine N-demethylation, testosterone and 17ss-estradiol hydroxylation patterns can provide new insights in the physiological function of P450 isoenzymes and the induction of the basal activities by chemicals. So far little interest was given to processes which occur after the DNA-receptor binding, e.g. changes in steroid hormone metabolism and pathways in environmental toxicology. This in spite of the fact that very subtle changes in steroid hormone levels may have significant physiological implications. This presentation will focus on some P450 activities, besides CYP1A(1), which might be important for development and reproduction. Some experimental approaches, limitations and techniques will be discussed which could lead to elucidation of the possible endocrine function of P450s.

  12. Evaluation of the fish biochemistry data from the Slave River monitoring program, NWT, 1988--1994

    SciTech Connect

    Williams, T.G.; Lockhart, W.L.; Metner, D.A.; Harbicht, S.

    1995-12-31

    With the possibility of impending industrial development in Northern Alberta and within the Slave River Basin, scientists and resource managers felt it appropriate that background data be collected to determine baseline concentrations for the Slave River basin. This monitoring program incorporated a suite of studies analyzing various components in the environment including fish, water, bottom sediment and suspended sediment. One aspect of the fish component included biochemical effects studies which comprised a series of MFO analyses on lake whitefish, burbot, walleye and northern pike. It is the purpose of this paper to describe the biochemical component of the Slave River Monitoring program. Physiological changes (i.e, in the form of EROD, AHH, P450 activity), age, weight, condition factor, liver and gonadal somatic indices were looked at. Limited conclusions were made with the lake whitefish and burbot data due to a conflict with the spawning season (i.e., MFO activity was depressed during spawning), however, a good data set has been collected for walleye and northern pike. Hepatic MFO enzyme activity indicated that some differences were evident in fish sampled from the Slave River relative to background/control lakes, however, in many cases no differences were observed. Five years of biochemical effects studies have determined that the Slave River has low levels of induction suggesting a relatively pristine environment, but further studies are required to confirm this.

  13. Effect of PAHs on MFO induction in common shrews (Crocidura russula)

    SciTech Connect

    Bosveld, A.T.C.; Bie, P. de; Weggemans, J.; Murk, A.

    1995-12-31

    PAHs are widespread environmental contaminants. Despite the relatively high turnover rates for enzymatic breakdown, PAHs have been detected in tissues from species at various trophic levels. As a consequence they have the potential to be passed on to the higher levels of the foodchain. As a model for the primary carnivores in the terrestrial foodchain the common shrew (Crocidura russula) is studied in the laboratories. The authors investigated the effect of exposure to benzo[a]pyrene (BaP) on cytochrome P450 isoenzymes in relation to the effect of a known strong inducer of the MFO system i.e. 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). The compounds were dissolved in oil and mixed with food. Shrews were exposed for a period of one week to BaP at concentrations equivalent to 10 or 100 mg/kg bodyweight per day (n = 3 for each dose group) and to TCDD at a concentration equivalent to 10 {micro}g/kg per day (n = 5). Controls received a diet with only the carier (oil) added. At termination of the experiment, hepatic CYP1A1 associated EROD activity was induced 20% in both the low and high dosed BaP group. In the TCDD exposed shrews EROD was induced up to 776% compared to the controls. Related MFO activities, including PROD, BROD, MROD and site specific testosterone hydroxylation are under investigation and the results will be presented. The relevance of MFO induction by PAHs and the use of these parameters as biomarkers for PAH exposure will be discussed.

  14. Organ specificity of aryl hydrocarbon hydroxylase induction by cigarette smoke

    SciTech Connect

    Yoshikawa, M.; Arashidani, K.; Kawamoto, T.; Kodama, Y. )

    1990-06-01

    Biotransformation of many chemicals found in cigarette smoke, such as PAHs and nitrosamines, is generally considered essential for the mutagenic, carcinogenic effects of these xenobiotics. In fact, the genotic action of these premutagens or precarcinogens is dependent on metabolic activation catalyzed by microsomal monooxygenases. The first enzymatic reaction of the PAHs metabolic pathway is catalyzed by a cytochrome P-450-dependent monooxygenase, the aryl hydrocarbon hydroxylase (AHH). AHH leads to the formation of reactive arene oxides, which are further metabolized by enzymatic and non-enzymatic reaction into many metabolites. AHH induction in laboratory animals exposed to cigarette smoke has also been reported, and the data show that this response is highly dependent on species and tissues. Exposure of small laboratory animals to cigarette smoke generally induces AHH in the kidney and lung, while the effect of cigarette smoke on the hepatic AHH activity appears variable.

  15. An Eroding Social Justice Agenda: The Case of Physical Education and Health Edu-Business in Schools.

    PubMed

    McCuaig, Louise; Enright, Eimear; Rossi, Anthony; Macdonald, Doune; Hansen, Scott

    2016-06-01

    In this article, we draw on current research to explore notions of socially just health and physical education (HPE) programs, in light of claims that a neoliberal globalization promotes markets over the states and a new individualism that privileges self-interest over the collective good. We also invite readers to consider the UN Educational, Scientific, and Cultural Organization's ambition for physical education in light of preliminary findings from an Australian-led research project exploring national and international patterns of outsourcing HPE curricula. Data were sourced from this international research project through a mixed-methods approach. Each external provider engaged in 4 phases of research activity: (a) Web audits, (b) interviews with external providers, (c) network diagrams, and (d) school partner interviews and observations. We then used these data to pose what we believe to be three emerging lines of inquiry and challenge for a socially just school HPE in neoliberal times. In particular, our data indicate that the marketization of school HPE is strengthening an emphasis on individual responsibility for personal health, thereby elevating expectations that schools and teachers will "fill the welfare gap" and, finally, influencing the nature and purchase of educative HPE programs in schools. The apparent proliferation of external providers of health work and HPE resources and services reflects the rise and pervasiveness of neoliberalism in education. We conclude that this global HPE landscape warrants attention to investigate the extent to which external providers' resources are compatible with schooling's educative and inclusive mandates.

  16. Regional Study of No-Till Impacts on Near-Surface Aggregate Properties that Influence Soil Erodibility

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The extent to which tillage systems modify the near-surface soil aggregate properties affecting soil’s susceptibility to erosion by water and wind is not well understood. We hypothesized that an increase in soil organic carbon (SOC) content with conservation tillage systems, particularly NT, may imp...

  17. Importance of the surface size distribution of erodible material: an improvement of the Dust Entrainment And Deposition DEAD

    NASA Astrophysics Data System (ADS)

    Mokhtari, M.; Gomes, L.; Tulet, P.; Rezoug, T.

    2011-11-01

    This paper is based on dust aerosol cycle modelling in the atmospheric model ALADIN (Aire Limitée Adaptation dynamique Développement InterNational) coupled with the EXternalised SURFace scheme SURFEX. Its main goal is to create a global mineral dust emission parameterization compatible with the global database of land surface parameters ECOCLIMAP and the Food and Agriculture Organization (FAO) soil type database in SURFEX, based on both Shao (1993) and Marticorena and Bergametti (1995) parameterizations. An arrangement on the Dust Entrainment And Deposition scheme (DEAD) is proposed in this paper by introducing the geographic variation of surface size distribution, the Marticorena and Bergametti (1995) formulation of horizontal saltation flux and the Shao (2001) formulation of sandblasting efficiency α. To show the importance of the modifications introduced in the code DEAD, both sensitivity and comparative studies are realized in 0 dimensions (0-D) and then in 3 dimensions (3-D) between the old DEAD and that developed in this paper. The results in the 0-D simulations indicate that the developed DEAD scheme represents the dust source emission better, particularly in the Bodélé depression and provides a reasonable friction threshold velocity. In 3-D simulations, small differences are found between the DEAD and developed DEAD schemes for the simulated Aerosol Optical Depth (AOD) compared with the photometer AErosol RObotic NETwork (AERONET) measurements available in the African Monsoon Multidisciplinary Analyses (AMMA) databases. But, for the surface concentration a remarkable improvement is noted for the developed DEAD scheme.

  18. Importance of the surface size distribution of erodible material: an improvement on the Dust Entrainment And Deposition (DEAD) Model

    NASA Astrophysics Data System (ADS)

    Mokhtari, M.; Gomes, L.; Tulet, P.; Rezoug, T.

    2012-05-01

    This paper is based on dust aerosol cycle modelling in the atmospheric model ALADIN (Aire Limitée Adaptation dynamique Développement InterNational) coupled with the EXternalised SURFace scheme SURFEX. Its main goal is to create an appropriate mineral dust emission parameterization compatible with the global database of land surface parameters ECOCLIMAP, and the Food and Agriculture Organization (FAO) soil type database in SURFEX. An improvement on the Dust Entrainment And Deposition scheme (DEAD) is proposed in this paper by introducing the geographical variation of surface soil size distribution, the Marticorena and Bergametti (1995) formulation of horizontal saltation flux and the Shao et al. (1996) formulation of sandblasting efficiency α. To show the importance of the modifications introduced in the DEAD, both sensitivity and comparative studies are conducted in 0 dimensions (0-D) and then in 3 dimensions (3-D) between the old DEAD and the new DEAD. The results of the 0-D simulations indicate that the revised DEAD scheme represents the dust source emission better, particularly in the Bodélé depression, and provides a reasonable friction threshold velocity. In 3-D simulations, small differences are found between the DEAD and the revised DEAD for the simulated Aerosol Optical Depth (AOD) compared with the AErosol RObotic NETwork (AERONET) photometer measurements available in the African Monsoon Multidisciplinary Analyses (AMMA) databases. For the surface concentration, a remarkable improvement is noted for the revised DEAD scheme.

  19. Beach morphology and food web structure: comparison of an eroding and an accreting sandy shore in the North Sea

    NASA Astrophysics Data System (ADS)

    Menn, Iris

    2002-09-01

    Food web components and inorganic nutrients were studied on two sandy shores of the adjacent barrier islands of Sylt and Rømø in the North Sea, differing in morphodynamics. Implications of high and low wave energy on the food web structure were assessed. The Sylt shore represents a dynamic intermediate beach type, while the Rømø shore is morphologically stable and dissipative. On the steep-profiled, coarse-grained Sylt shore, strong hydrodynamics resulted in erosion and high fluxes of organic material through the beach, but prevented any storage of food sources. In contrast, the flat-profiled, fine-grained Rømø shore, with low wave energy and accretion, accumulated organic carbon from surf waters. At Sylt, oxic nutrient regeneration prevailed, while anoxic mineralization was more important at Rømø. Macrofauna on the Sylt shore was impoverished compared with the community at Rømø. Correspondingly, abundances of epibenthic predators such as shrimps, crabs, fish, and shorebirds were also lower at Sylt. Meiofauna was abundant on both shores, but differed in taxonomic composition. Several major taxa were represented in fairly equal proportions of individual numbers on the well-oxygenated Sylt shore, while nematodes strongly dominated the assemblage at Rømø. Thus, on cold-temperate, highly dynamic intermediate shores with high wave energy and subject to erosion, the "small food web" dominates. Organisms are agile and quickly exploit fresh organic material. Larger organisms and nematodes abound under stable, dissipative and accreting shore conditions, where some food materials may accumulate and zoomass builds up to support numerous visitors from higher trophic levels.

  20. Eroding and Inflating the Atacama Desert, Chile: Insights Through Cosmogenic 10-Be, 26-Al and 21-Ne

    NASA Astrophysics Data System (ADS)

    Heimsath, A. M.; Jungers, M. C.; Amundson, R.; Balco, G.; Shuster, D. L.

    2010-12-01

    Enigmas of the Atacama Desert are as abundant as the hypotheses formulated to explain them. This fascinating and extreme landscape attracts scientists from disparate disciplines, spawning remarkable insights into the connections between climate, tectonics, biota and landscape evolution. Recent work explores such connections on timescales ranging from millions to thousands of years. Both the timing of the onset of hyperaridity in the Atacama and its relationship to the uplift of the Andes are especially well-debated topics. Similarly enigmatic, but less widely studied, are the connections between the timing of hyperaridity and the surface morphology of the region. Specifically, the extent, nature, and timing of formation for the extensive salars across the Atacama are undeniably linked to the climate history of the region. Adjacent to the extensive salars are landscapes that appear to be shaped by processes more typically associated with temperate landscapes: rilling and gullying, extensive terrace deposition, steep fault scarps, landslide deposits, and extensive fan and paleosurface deposits. Our primary goal in this project is to establish chronologies and rates for the surface processes driving landscape evolution for two field regions in the Atacama. To achieve this goal we are also testing and expanding upon the burial dating methodology (Balco and Shuster, 2009) that couples the stable cosmogenic nuclide, 21Ne, with the radiogenic nuclides, 10Be and 26Al. Here we present new results from remarkably different field settings from the north-central Atacama. The southern region, inland from Antofagasta, is relatively well studied to determine how the onset of hyperaridity impacted water-driven processes. The northern region, north of the Rio Loa and Calama, differs most notably by the enormous basin fills of salt (e.g. Salar de Llamara and Salar Grande) and evidence of more extensive recently active salars. Across both regions we use in 10Be, 26Al, and 21Ne to quantify surface chronologies as well as the processes shaping these unusual landscapes. To do so we have combined standard surface exposure dating with an application of the burial and profile-dating methodology to surfaces that are expanding by salt inflation. Profiles of these nuclides are used to test simple end-member models for the timescale of surface inflation and initial results support Mio-Pliocene ages for landscapes previously dated by other methods. We also use profiles and burial-age methods to date and better estimate potential inheritance in the nuclide signals for extensive cobble deposits thought to originate from the Andes prior to the onset of hyperaridity. Preliminary results support Miocene deposition, which may suggest a significantly more recent onset time for hyperaridity than others have estimated.

  1. Using landscape restoration to increase crop yield and improve soil quality on severely eroded hilltops in southwestern Manitoba

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Tillage erosion is the dominant soil erosion process in cultivated hilly landscapes in Western Canada. Organic-rich topsoil is removed from convex upper slope positions and accumulates in concave lower slope positions. The loss of topsoil on hilltops results in poor soil quality and ultimately a red...

  2. Influence of benthic macroinvertebrates on the erodability of estuarine cohesive sediments: Density- and biomass-specific responses

    NASA Astrophysics Data System (ADS)

    Kristensen, Erik; Neto, João Magalhães; Lundkvist, Morten; Frederiksen, Lars; Pardal, Miguel Ângelo; Valdemarsen, Thomas; Flindt, Mogens Rene

    2013-12-01

    The impact of three dominating benthic invertebrates on sediment stability and erosion conditions of cohesive sediments in the Mondego Estuary, Portugal, was examined in laboratory annular flume experiments. The purpose was to test how the life habits and body size of the three involved species (Hydrobia ulvae, Nereis diversicolor and Scrobicularia plana) in terms of density or biomass influence sediment erosion. All three species decreased the free-stream erosion threshold (uc) and increased erosion rate (E), since their feeding activities diminished the surface stabilizing effect of extracellular polymeric substances (EPS) produced by microphytobenthos. S. plana had the highest and H. ulvae the lowest impact when related to density (factor of 29 for uc and factor of 19 for E), while H. ulvae was more important than S. plana when related to biomass (factor of 4 for uc and factor of 6 for E). N. diversicolor had intermediate density-specific (4-6 times higher than H. ulvae) and lowest biomass-specific (2-3 times lower than S. plana) effects on erosion. It appears that faunal erosion impacts preferably should be reported in biomass units for comparative purposes because individual behavioural effects of a small-bodied species like H. ulvae functionally can be relatively more important than those of a 100 times heavier S. plana individual. This is clearly evidenced from the strongly diminished response in suspended Chlorophyll-a content in the presence of the former than the latter species, which is caused by an efficient microphytobenthos grazing by H. ulvae. It is also important to emphasize that the total faunal impact on erosion threshold in a certain area is dictated by combination of contributions from individual species. The total outcome is unpredictable and controlled by synergistic and antagonistic species-specific effects, species interactions as well as environmental and sediment conditions.

  3. 7 CFR Exhibit M to Subpart G of... - Implementation Procedures for the Conservation of Wetlands and Highly Erodible Land Affecting...

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ..., equivalent source of revenues or, if possible, agree to undertake any steps necessary to gain eligibility for... programs as a source of funds to repay its FmHA or its successor agency under Public Law 103-354 loan(s... their projected sources of repayment, potential funds from any USDA program subject to some form...

  4. 7 CFR Exhibit M to Subpart G of... - Implementation Procedures for the Conservation of Wetlands and Highly Erodible Land Affecting...

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ..., equivalent source of revenues or, if possible, agree to undertake any steps necessary to gain eligibility for... programs as a source of funds to repay its FmHA or its successor agency under Public Law 103-354 loan(s... their projected sources of repayment, potential funds from any USDA program subject to some form...

  5. 7 CFR Exhibit M to Subpart G of... - Implementation Procedures for the Conservation of Wetlands and Highly Erodible Land Affecting...

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ..., equivalent source of revenues or, if possible, agree to undertake any steps necessary to gain eligibility for... programs as a source of funds to repay its FmHA or its successor agency under Public Law 103-354 loan(s... their projected sources of repayment, potential funds from any USDA program subject to some form...

  6. 7 CFR Exhibit M to Subpart G of... - Implementation Procedures for the Conservation of Wetlands and Highly Erodible Land Affecting...

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ..., equivalent source of revenues or, if possible, agree to undertake any steps necessary to gain eligibility for... programs as a source of funds to repay its FmHA or its successor agency under Public Law 103-354 loan(s... their projected sources of repayment, potential funds from any USDA program subject to some form...

  7. 7 CFR Exhibit M to Subpart G of... - Implementation Procedures for the Conservation of Wetlands and Highly Erodible Land Affecting...

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ..., equivalent source of revenues or, if possible, agree to undertake any steps necessary to gain eligibility for... programs as a source of funds to repay its FmHA or its successor agency under Public Law 103-354 loan(s... their projected sources of repayment, potential funds from any USDA program subject to some form...

  8. Full-mouth adhesive rehabilitation of a severely eroded dentition: the three-step technique. Part 3.

    PubMed

    Vailati, Francesca; Belser, Urs Christoph

    2008-01-01

    Dental erosion is a frequently underestimated pathology that nowadays affects an increasing number of younger individuals. Often the advanced tooth destruction is the result of not only a difficult initial diagnosis (e.g. multifactorial etiology of tooth wear), but also a lack of timely intervention. A clinical trial testing a fully adhesive approach for patients affected by severe dental erosion is underway at the School of Dental Medicine of the University of Geneva. All the patients are systematically and exclusively treated with adhesive techniques, using onlays in the posterior region and a combination of facially bonded porcelain restorations and indirect palatal resin composite restorations in the anterior maxillary region. To achieve maximum preservation of tooth structure and predict the most esthetic and functional outcome, an innovative concept has been developed: the three-step technique. Three laboratory steps are alternated with three clinical steps, allowing the clinician and the dental technician to constantly interact during the planning and execution of a full-mouth adhesive rehabilitation. In this article, the third and last step of the three-step technique has been described in detail.

  9. Defensive Projection, Superimposed on Simplistic Object Relations, Erodes Patient-Provider Relationships in High-Risk Pregnancy: An Empirical Investigation

    PubMed Central

    Shahar, Golan; Porcerelli, John H.; Kamoo, Ray; Epperson, C. Neill; Czarkowski, Kathryn A.; Magriples, Urania; Mayes, Linda C.

    2014-01-01

    In an attempt to illustrate the relevance of psychoanalytic theory and research to behavior medicine, an empirical investigation was conducted of females treated at a high-risk pregnancy specialty clinic (N = 58). Drawing from psychoanalytic object relations theory, it was hypothesized and confirmed that use of projection as a defense mechanism during pregnancy, superimposed on simplistic object relations, predicted an erosion of patient-provider relationships during the pregnancy/postdelivery period. Findings are interpreted through the perspective of mentalization, pertaining to individuals' ability to understand the mental states of self and others, specifically under significant stress. Implications for psychoanalytically oriented assessment and treatment, and for the rift between psychoanalysis and research, are discussed. PMID:21156840

  10. Work-First Federal Policies: Eroding Access to Community Colleges for Latinos and Low-Income Populations

    ERIC Educational Resources Information Center

    Shaw, Kathleen M.; Goldrick-Rab, Sara

    2006-01-01

    This chapter describes how the implementation of the 1996 welfare reform and the 1998 Workforce Investment Acts affected community colleges' willingness and capacity to provide access to postsecondary education and training for Latinos and other low-income populations. (Contains 3 figures.)

  11. Biogeochemical Controls on Biodegradation of MC252 Oil:Sand Aggregates on a Rapidly Eroding Coastal Headland Beach

    NASA Astrophysics Data System (ADS)

    Pardue, J.; Elango, V.; Urbano, M.; Lemelle, K.

    2012-12-01

    The research described below was conducted on Fourchon Beach, a coastal headland consisting of nine miles of fairly pristine sandy beaches and dunes, backed by wetlands and tidal channels, located between Belle Pass tidal inlet on the west and Elmer's Island on the east in Lafourche Parish, Louisiana. MC252 oil first arrived in large quantities on Fourchon Beach on or around May 20, 2010. A unique oil form created under these conditions was an aggregate of sand and emulsified oil, typically 0.1-10 cm in diameter, termed small surface residue balls (SSRBs). The work from this project made critical measurements on the factors controlling biodegradability of these SSRB aggregates. SSRB aggregates were sampled across transects perpendicular to the beach from the intertidal to the supratidal. Areas in the supratidal that were sampled initially were set aside for research purposes and not altered by any clean-up activities. Chemical composition of SSRBs was measured including concentrations of n-alkanes, PAHs, hopanes, nutrients (nitrate, nitrite, ammonium and orthophosphate measured on water extracts of SSRBs), and electron acceptor concentrations (O2 microprofiles measured on intact SSRBs and sulfate). Physical characterization of the SSRBs including length and area dimensions, mass, density, porosity, moisture content, and salinity using standard methods. Microbial characterization of SSRBs was also conducted using denaturing gradient gel electrophoresis and sequencing of dominant bands. SSRBs were sampled from various locations across the beach profile deposited by 2 significant tropical events in 2010; Hurricane Alex and TS Bonnie, and one event in 2011, TS Lee. Sampling focused on comparing and contrasting impacts of biogeochemistry on weathering of oil stranded in three beach microenvironments; supratidal surface; subtidal subsurface which is permanently inundated and intertidal subsurface samples which are intermittently inundated. The three types of oil are dramatically different in appearance and have a distinctive chemical signature indicative of different rates of weathering. Supratidal surface samples were depleted in n-alkanes and lower-molecular weight PAHs. Geochemically, aggregates located in these environments had low salinities (1.3-1.5 ppt), O2 at near saturation throughout the aggregates and nutrient concentrations (N and P) significantly lower than SSRBs deposited in the intertidal and subtidal. Intertidal and subtidal subsurface oil samples were characterized by elevated nutrient concentrations and salinities consistent with regular seawater inundation. Complete inundation leads to O2 consumption in the aggregates after several days. Despite the presence of elevated nutrients, PAHs and n-alkanes were comparatively unweathered in the subtidal subsurface samples consistent with O2 limitations. Sequences of known PAH degraders were isolated from the supratidal and intertidal aggregates. The results to be presented support the hypothesis that SSRBs deposited at different locations on the beach have different biogeochemical characteristics . These characteristics are due, in part, to their location on the landscape.

  12. An Eroding Social Justice Agenda: The Case of Physical Education and Health Edu-Business in Schools

    ERIC Educational Resources Information Center

    McCuaig, Louise; Enright, Eimear; Rossi, Anthony; Macdonald, Doune; Hansen, Scott

    2016-01-01

    In this article, we draw on current research to explore notions of socially just health and physical education (HPE) programs, in light of claims that a neoliberal globalization promotes markets over the states and a new individualism that privileges self-interest over the collective good. We also invite readers to consider the UN Educational,…

  13. Wind erodibility of soils at Fort Irwin, California (Mojave Desert), USA, before and after trampling disturbance: Implications for land management

    USGS Publications Warehouse

    Belnap, J.; Phillips, S.L.; Herrick, J.E.; Johansen, J.R.

    2007-01-01

    Recently disturbed and 'control' (i.e. less recently disturbed) soils in the Mojave Desert were compared for their vulnerability to wind erosion, using a wind tunnel, before and after being experimentally trampled. Before trampling, control sites had greater cyanobacterial biomass, soil surface stability, threshold friction velocities (TFV, i.e. the wind speed required to move soil particles), and sediment yield than sites that had been more recently disturbed by military manoeuvres. After trampling, all sites showed a large drop in TFVs and a concomitant increase in sediment yield. Simple correlation analyses showed that the decline in TFVs and the rise in sediment yield were significantly related to cyanobacterial biomass (as indicated by soil chlorophyll a). However, chlorophyll a amounts were very low compared to chlorophyll a amounts found at cooler desert sites, where chlorophyll a is often the most important factor in determining TFV and sediment yield. Multiple regression analyses showed that other factors at Fort Irwin were more important than cyanobacterial biomass in determining the overall site susceptibility to wind erosion. These factors included soil texture (especially the fine, medium and coarse sand fractions), rock cover, and the inherent stability of the soil (as indicated by subsurface soil stability tests). Thus, our results indicate that there is a threshold of biomass below which cyanobacterial crusts are not the dominant factor in soil vulnerability to wind erosion. Most undisturbed soil surfaces in the Mojave Desert region produce very little sediment, but even moderate disturbance increases soil loss from these sites. Because current weathering rates and dust inputs are very low, soil formation rates are low as well. Therefore, soil loss in this region is likely to have long-term effects.

  14. An Eroding Social Justice Agenda: The Case of Physical Education and Health Edu-Business in Schools.

    PubMed

    McCuaig, Louise; Enright, Eimear; Rossi, Anthony; Macdonald, Doune; Hansen, Scott

    2016-06-01

    In this article, we draw on current research to explore notions of socially just health and physical education (HPE) programs, in light of claims that a neoliberal globalization promotes markets over the states and a new individualism that privileges self-interest over the collective good. We also invite readers to consider the UN Educational, Scientific, and Cultural Organization's ambition for physical education in light of preliminary findings from an Australian-led research project exploring national and international patterns of outsourcing HPE curricula. Data were sourced from this international research project through a mixed-methods approach. Each external provider engaged in 4 phases of research activity: (a) Web audits, (b) interviews with external providers, (c) network diagrams, and (d) school partner interviews and observations. We then used these data to pose what we believe to be three emerging lines of inquiry and challenge for a socially just school HPE in neoliberal times. In particular, our data indicate that the marketization of school HPE is strengthening an emphasis on individual responsibility for personal health, thereby elevating expectations that schools and teachers will "fill the welfare gap" and, finally, influencing the nature and purchase of educative HPE programs in schools. The apparent proliferation of external providers of health work and HPE resources and services reflects the rise and pervasiveness of neoliberalism in education. We conclude that this global HPE landscape warrants attention to investigate the extent to which external providers' resources are compatible with schooling's educative and inclusive mandates. PMID:27100057

  15. Runoff and sediment responses to grazing native and introduced species on highly erodible Southern Great Plains soil

    NASA Astrophysics Data System (ADS)

    Wine, Michael L.; Zou, Chris B.; Bradford, James A.; Gunter, Stacey A.

    2012-07-01

    SummaryOld World Bluestems, such as yellow bluestem (Bothriochloa ischaemum), have been seeded extensively in the Southern Great Plains because they are responsive to nitrogen fertilization and allow for higher stocking rates. From 1991 to 2005, we measured the effects of moderately grazing prairie species and heavily grazing fertilized yellow bluestem on runoff, sediment yield, leaf litter cover, and aboveground plant biomass for four adjacent watersheds located at the USDA-ARS Southern Plains Range Research Station in the sub-humid Rolling Red Plains of western Oklahoma. Here we show that factors other than leaf litter cover and biomass determine variation in runoff when leaf litter exceeds 70%. Runoff was related to grazing rate and storm size and inversely related to storm duration. Rainfall thresholds were similar between the moderately grazed prairie watersheds (15 mm) and the heavily grazed yellow bluestem watersheds (18 mm); however, the slope of the rainfall-runoff curve from heavily grazed yellow bluestem (0.242) was steeper than that of moderately grazed prairie (0.087). Slightly higher runoff from heavily grazed yellow bluestem relative to moderately grazed prairie may occur due to compaction of both the leaf litter and topsoil. Sediment yield was low from moderately grazed native prairie and heavily grazed yellow bluestem. Our findings indicate that both treatments assessed appear hydrologically sustainable.

  16. Non-Intrusive Sensor for In-Situ Measurement of Recession Rate of Ablative and Eroding Materials

    NASA Technical Reports Server (NTRS)

    Papadopoulos, George (Inventor); Tiliakos, Nicholas (Inventor); Benel, Gabriel (Inventor); Thomson, Clint (Inventor)

    2014-01-01

    A non-intrusive sensor for in-situ measurement of recession rate of heat shield ablatives. An ultrasonic wave source is carried in the housing. A microphone is also carried in the housing, for collecting the reflected ultrasonic waves from an interface surface of the ablative material. A time phasing control circuit is also included for time-phasing the ultrasonic wave source so that the waves reflected from the interface surface of the ablative material focus on the microphone, to maximize the acoustic pressure detected by the microphone and to mitigate acoustic velocity variation effects through the material through a de-coupling process that involves a software algorithm. A software circuit for computing the location off of which the ultrasonic waves scattered to focus back at the microphone is also included, so that the recession rate of the heat shield ablative may be monitored in real-time through the scan-focus approach.

  17. A false sense of security: safety behaviors erode objective speech performance in individuals with social anxiety disorder.

    PubMed

    Rowa, Karen; Paulitzki, Jeffrey R; Ierullo, Maria D; Chiang, Brenda; Antony, Martin M; McCabe, Randi E; Moscovitch, David A

    2015-05-01

    In the current study, 55 participants with a diagnosis of generalized social anxiety disorder (SAD), 23 participants with a diagnosis of an anxiety disorder other than SAD with no comorbid SAD, and 50 healthy controls completed a speech task as well as self-reported measures of safety behavior use. Speeches were videotaped and coded for global and specific indicators of performance by two raters who were blind to participants' diagnostic status. Results suggested that the objective performance of people with SAD was poorer than that of both control groups, who did not differ from each other. Moreover, self-reported use of safety behaviors during the speech strongly mediated the relationship between diagnostic group and observers' performance ratings. These results are consistent with contemporary cognitive-behavioral and interpersonal models of SAD and suggest that socially anxious individuals' performance skills may be undermined by the use of safety behaviors. These data provide further support for recommendations from previous studies that the elimination of safety behaviors ought to be a priority in cognitive behavioral therapy for SAD.

  18. A model based on Hirano-Exner equations for two-dimensional transient flows over heterogeneous erodible beds

    NASA Astrophysics Data System (ADS)

    Juez, C.; Ferrer-Boix, C.; Murillo, J.; Hassan, M. A.; García-Navarro, P.

    2016-01-01

    In order to study the morphological evolution of river beds composed of heterogeneous material, the interaction among the different grain sizes must be taken into account. In this paper, these equations are combined with the two-dimensional shallow water equations to describe the flow field. The resulting system of equations can be solved in two ways: (i) in a coupled way, solving flow and sediment equations simultaneously at a given time-step or (ii) in an uncoupled manner by first solving the flow field and using the magnitudes obtained at each time-step to update the channel morphology (bed and surface composition). The coupled strategy is preferable when dealing with strong and quick interactions between the flow field, the bed evolution and the different particle sizes present on the bed surface. A number of numerical difficulties arise from solving the fully coupled system of equations. These problems are reduced by means of a weakly-coupled strategy to numerically estimate the wave celerities containing the information of the bed and the grain sizes present on the bed. Hence, a two-dimensional numerical scheme able to simulate in a self-stable way the unsteady morphological evolution of channels formed by cohesionless grain size mixtures is presented. The coupling technique is simplified without decreasing the number of waves involved in the numerical scheme but by simplifying their definitions. The numerical results are satisfactorily tested with synthetic cases and against experimental data.

  19. Microbial interactions in marine water amended by eroded benthic biofilm: A case study from an intertidal mudflat

    NASA Astrophysics Data System (ADS)

    Montanié, Hélène; Ory, Pascaline; Orvain, Francis; Delmas, Daniel; Dupuy, Christine; Hartmann, Hans J.

    2014-09-01

    In shallow macrotidal ecosystems with large intertidal mudflats, the sediment-water coupling plays a crucial role in structuring the pelagic microbial food web functioning, since inorganic and organic matter and microbial components (viruses and microbes) of the microphytobenthic biofilm can be suspended toward the water column. Two experimental bioassays were conducted in March and July 2008 to investigate the importance of biofilm input for the pelagic microbial and viral loops. Pelagic inocula (< 0.6 μ- and < 10 μ filtrates) were diluted either with < 30 kDa-ultrafiltered seawater or with this ultrafiltrate enriched with the respective size-fractionated benthic biofilm or with < 30 kDa-benthic compounds (BC). The kinetics of heterotrophic nanoflagellates (HNF), bacteria and viruses were assessed together with bacterial and viral genomic fingerprints, bacterial enzymatic activities and viral life strategies. The experimental design allowed us to evaluate the effect of BC modulated by those of benthic size-fractionated microorganisms (virus + bacteria, + HNF). BC presented (1) in March, a positive effect on viruses and bacteria weakened by pelagic HNF. Benthic microorganisms consolidated this negative effect and sustained the viral production together with a relatively diverse and uneven bacterial assemblage structure; (2) in July, no direct impact on viruses but a positive effect on bacteria modulated by HNF, which indirectly enhanced viral multiplication. Both effects were intensified by benthic microorganisms and bacterial assemblage structure became more even. HNF indirectly profited from BC more in March than in July. The microbial loop would be stimulated by biofilm during periods of high resources (March) and the viral loop during periods of depleted resources (July).

  20. Letdown valve (anti eroded type for slurry use) on 150 t/d coal liquefaction pilot plant

    SciTech Connect

    Kamada, Mitsushi; Kobayashi, Masatoshi; Yoshida, Haruhiko; Yamagiwa, Hisashi

    1999-07-01

    The letdown valve developed by NEDO has been tested on the 150 t/d coal liquefaction pilot plant using the NEDOL process for more than 6,000 hours of on-coal operation. Several factors affecting the damage of the letdown valve that handled a fluid containing coal-derived oil, catalyst and residue including ash have been evaluated. The countermeasure for the damage has been studied to develop an advanced letdown valve to be used demonstration plant.

  1. The Gaissa Nappe, Finnmark, North Norway: an example of a deeply eroded external imbricate zone within the Scandinavian Caledonides

    NASA Astrophysics Data System (ADS)

    Townsend, C.; Roberts, D.; Rice, A. H. N.; Gayer, R. A.

    The Lower Allochthon of the Caledonides of Finnmark, northern Norway, is represented solely by the Gaissa Nappe, which is composed of sub-greenschist facies sedimentary rocks of late Riphean to Tremadoc age. The lithostratigraphic sequence has been shortened by thrusting and folding in an ESE direction. Based on mapping and structural profiling east of Porsangerfjord, the Gaissa Nappe can be divided into four structural segments: the Børsely duplex, developed beneath the Kalak Nappe of the Middle Allochthon, is oblique to an imbricate fan, the Munkavarri imbricate zone, east of which is the Guiverassa duplex zone that is partly covered by the Vuonjalrassa thrust sheet. The sole thrust to the Gaissa Nappe is a flat planar surface which truncates the common N-S folds and associated cleavage in the rocks of the Gaissa Nappe. The Vuonjalrassa-Gaissa thrust cuts down section in the transport direction, possibly as a result of early tectonic downwarping. A balanced cross-section and a hanging-wall diagram have been partially restored, indicating that the metasediments of the trailing edge of the Munkavarri imbricate zone have been displaced by 104 km in their ESE translation direction. Taking the sequence west of Porsangerfjord into consideration, an overall contraction of more than 150 km is possible. In the east, it is argued that the basal Gaissa décollement, formerly thought to die out and pass laterally into an unconformity, extends to the northeast beyond the head of Tanafjord. Folds that occur in front of the sole thrust on the Varanger Peninsula imply the presence of a blind thrust. In an orogenic context, the Gaissa Nappe forms a series of imbricated thrust sheets in the external part to the collision belt, produced during the Finnmarkian orogenic event in late Cambrian to early Ordovician time.

  2. Potential dust production from wind-erodible soils on the Southern High Plains and Chihuahuan Desert: preliminary figures

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Blowing Dust is a common occurrence on the Southern High Plains of West Texas and Eastern New Mexico and the Chihuahuan Desert in southern New Mexico, Far West Texas, and northern Chihuahua, Mexico. We collected sixty two surface soil samples from locations identified on satellite imagery as produci...

  3. School Enrollment among Urban Non-Slum, Slum and Rural Children in Kenya: Is the Urban Advantage Eroding?

    ERIC Educational Resources Information Center

    Mugisha, Frederick

    2006-01-01

    For long now, the urban child has been considered to be more likely than his/her rural counterpart in being able to realize the dream of fully participating in school. This observation has mainly been attributed to what is commonly known as the "urban advantage." This "urban advantage" is associated with increased access to facilities such as…

  4. Design of Controlled Release Non-erodible Polymeric Matrix Tablet Using Microwave Oven-assisted Sintering Technique.

    PubMed

    Patel, Dm; Patel, Bk; Patel, Ha; Patel, Cn

    2011-07-01

    The objective of the present study was to evaluate the effect of sintering condition on matrix formation and subsequent drug release from polymer matrix tablet for controlled release. The present study highlights the use of a microwave oven for the sintering process in order to achieve more uniform heat distribution with reduction in time required for sintering. We could achieve effective sintering within 8 min which is very less compared to conventional hot air oven sintering. The tablets containing the drug (propranolol hydrochloride) and sintering polymer (eudragit S-100) were prepared and kept in a microwave oven at 540 watt, 720 watt and 900 watt power for different time periods for sintering. The sintered tablets were evaluated for various tablet characteristics including dissolution study. Tablets sintered at 900 watt power for 8 min gave better dissolution profile compared to others. We conclude that microwave oven sintering is better than conventional hot air oven sintering process in preparation of controlled release tablets. PMID:21897655

  5. State trends in premiums and deductibles, 2003-2011: eroding protection and rising costs underscore need for action.

    PubMed

    Schoen, Cathy; Lippa, Jacob; Collins, Sara; Radley, David

    2012-12-01

    Rapidly rising health insurance premiums and higher cost-sharing continue to strain the budgets of U.S. working families and employers. Analysis of state trends in private employer-based health insurance from 2003 to 2011 reveals that premiums for family coverage increased 62 percent across states--rising far faster than income for middle- and low-income families. At the same time, deductibles more than doubled in large and small firms. Workers are thus paying more but getting less-protective benefits. If trends continue at their historical rate, the average premium for family coverage will reach nearly $25,000 by 2020. The Affordable Care Act's reforms should begin to moderate costs while improving coverage. But with private insurance costs projected to increase faster than incomes over the next decade, further efforts are needed. If annual premium growth slowed by one percentage point, by 2020 employers and families would save $2,029 annually for family coverage.

  6. Detection of aryl hydrocarbon hydroxylase activity in normal and neoplastic human breast epithelium

    SciTech Connect

    Greiner, J.W.; Malan-Shibley, L.B.; Janss, D.H.

    1980-01-28

    Studies were conducted to determine whether normal and/or neoplastic (MCF-7) human breast epithelial cells contain the microsomal aryl hydrocarbon hydroxylase (AHH) which catalyses the conversion of polycyclic aromatic hydrocarbons (PAH) to carcinogenic intermediates. Low constitutive levels of AHH activity were found in homogenates of both normal human breast epithelial and MCF-7 cells. The addition of 7,12-dimethylbenz(a)anthracene (DMBA) to the culture medium of either cell type significantly increased AHH activity. Peak induction of hydroxylase activity occurred following the in vitro addition of 10 ..mu..M DMBA. A time course of DMBA-induced AHH activity in both normal human breast epithelium and MCF-7 cells revealed maximal induction 16 hr after 10 ..mu..M DMBA was added to the culture medium. Benzo(a)pyrene (BP), 3-methylcholanthrene (MCA) and benz(a)anthracene (BA) also induced AHH activity in normal and MCF-7 cells. For example, the addition of 10 ..mu..M BP to the culture medium of either normal human breast epithelial or MCF-7 cells for 16 hr increased AHH activity 13.8 and 65.3-fold, respectively. For all PAH, the magnitude of AHH induction was substantially greater in MCF-7 than normal breast epithelial cells. Finally, ..cap alpha..-naphthoflavone inhibited BA-induced AHH activity in MCF-7 cells. The study demonstrates the presence of a PAH-inducible AHH enzyme(s) in normal human breast epithelial cells grown in primary culture and in the human breast tumor cell line, MCF-7.

  7. Effects of multiple exposures of small doses of Pembina Cardium crude oil and diesel in rats.

    PubMed

    Khan, A A; Coppock, R W; Schuler, M M

    2001-04-01

    In lands used for agricultural purposes, petroleum- or diesel-contaminated wastes and accidental spills of crude oil at some drilling sites pose exposure risks for occupational public, livestock, and wildlife. This study has assessed the effects of an Alberta crude oil, Pembina Cardium crude oil (PCCO), and a commercial diesel fuel #2 (CDF-2) in Sprague-Dawley rats after repeated exposures at small dose levels. Rats were given by gavage on day 1, 3, 5, and 8 specified dosages of either the control vehicle, methylcellulose (MC) (1.25 ml/kg), or PCCO (0.25-1.25 ml/kg), or CDF-2 (1.25 ml/kg). Exposure of rats to these dose levels of the test substances caused no overt symptoms of intoxication. A small but statistically significant increase in liver somatic index was observed in rats exposed to 1.25 ml/kg doses of PCCO and CDF-2; however, kidney somatic index was not significantly affected by these treatments. Blood analyses for hematological and clinical indicators of systemic impairments did not show any significant changes (p > 0.05) between the control and PCCO- or CDF-2-exposed rats. Biochemical assessment of liver and kidney tissues showed that compared to the control group, the PCCO- and CDF-2-exposed groups had a marked and significant increase (p < 0.05) in the hepatic activity of ethoxyresorufin-O-deethylase (EROD, a cytochrome P-450 [CYP] 1A1/A2-linked enzyme). In PCCO-exposed rats, the induction of EROD was dose-dependent. Exposure of rats with PCCO and CDF-2 also caused dose-related increases from the unexposed (control) or MC dosed rats in (1) hepatic activities of aryl hydrocarbon hydroxylase (AHH, a CYP 1A1-linked enzyme), ethoxycoumarin-O-deethylase (ECOD, a CYP 2B/1A-linked enzyme), glutathione transferase (GT), and NADPH-catalyzed microsomal lipid peroxidation; and (ii) ECOD activity in kidneys. The induction of hepatic CYP-linked enzymatic activities by PCCO and CDF-2 could be due to de novo synthesis of selected isoforms, as evidenced by the

  8. Evaluation of a two-generation reproduction toxicity study adding endpoints to detect endocrine disrupting activity using lindane.

    PubMed

    Matsuura, Ikuo; Saitoh, Tetsuji; Tani, Einosuke; Wako, Yumi; Iwata, Hiroshi; Toyota, Naoto; Ishizuka, Yoshihito; Namiki, Masato; Hoshino, Nobuhito; Tsuchitani, Minoru; Ikeda, Yasuo

    2005-12-01

    in T3 and/or T4 in both sexes and generations at 300 ppm were presumed to be secondary changes associated with the induction of hepatic drug-metabolizing enzymes. Blood hormone analysis revealed no changes in sex hormones attributable to lindane in males or females. Hepatic drug-metabolizing enzyme activities were increased dose-dependently from 10 ppm in both sexes and generations, with the rise in BROD activity being the most prominent. There were also increases in MROD, EROD, T-6beta-OH, and T4-UDP-GT activities (BROD > EROD > MROD, T-6beta-OH, T4-UDP-GT). This suggests that while lindane most strongly induces CYP2B, it also upregulates a number of other drug metabolizing enzymes, such as CYP1A, CYP3A, and UDP-GT. As for effects on reproductive function, lack of maternal behavior, including lactation and retrieval behavior, and consequent total litter loss were observed in F1 dams at 300 ppm. There were no effects of lindane on the estrous cycle, spermatogenesis, mating, fertility, pregnancy, or parturition. Neonatal toxicity was observed in both sexes and generations, including suppressed body weight gain at 60 and 300 ppm, and decreased thymus and spleen weights without histological change at 300 ppm. The postnatal survival rate in F2 offspring was decreased due to lack of maternal behavior in dams at 300 ppm.

  9. Biotransformation and Oxidative Stress Responses in Captive Nile Crocodile (Crocodylus niloticus) Exposed to Organic Contaminants from the Natural Environment in South Africa.

    PubMed

    Arukwe, Augustine; Røsbak, Randi; Adeogun, Aina O; Langberg, Håkon A; Venter, Annette; Myburgh, Jan; Botha, Christo; Benedetti, Maura; Regoli, Francesco

    2015-01-01

    In the present study, the biotransformation and oxidative stress responses in relation to chemical burden in the liver of male and female Nile crocodiles--Crocodylus niloticus--from a commercial crocodile farm passively exposed to various anthropogenic aquatic pollutants was investigated. In general, the data showed that male crocodiles consistently produced higher biotransformation and oxidative stress responses compared to females. Relationships between these responses and concentrations of aliphatic hydrocarbons and polycyclic aromatic hydrocarbons (PAHs) were also observed. Specifically, the catalytic assays for EROD and BROD (not PROD and MROD) showed sex-differences between male and female crocodiles and paralleled immunochemically determined CYP1A and CYP3A protein levels; the relatively similar levels of PAHs in both sexes suggest an estrogen-mediated reduction of this pathway in females. The antioxidant system exhibited higher levels in male crocodiles with slight or significant higher values for catalase (CAT), glutathione reductase (GR), glutathione peroxidases-H2O2 (GPx-H2O2), glutathione peroxidases-Cu (GPx-Cu), total antioxidant capacity towards peroxyl radicals (TOSC-ROO) and hydroxyl radicals (TOSC-HO), total glutathione (GSH) and malondialdehyde (MDA). On the other hand, the activities of acyl-CoA oxidase (AOX) and glutathione S-transferases (GST) were significantly higher in females. Principal component analysis (PCA) produced significant groupings that revealed correlative relationships (both positive and negative) between biotransformation/oxidative stress variables and liver PAHs and aliphatic hydrocarbon burden. The overall results suggest that these captive pre-slaughter crocodiles exhibited adverse exposure responses to anthropogenic aquatic contaminants with potentially relevant effects on key cellular pathways, and these responses may be established as relevant species biomarkers of exposure and effects in this endangered species.

  10. Investigation of eggshell thickness and biochemical indicators of contaminant exposure in Great Blue Herons(Ardea herodias) from Mason Neck National Wildlife Refuge

    USGS Publications Warehouse

    Johnson, K.N.; Pinkney, A.E.; Melancon, M.J.; Hoffman, D.J.

    2001-01-01

    Mason Neck National Wildlife Refuge supports the largest great blue heron (Ardea herodias) rookery in the State of Virginia. The presence of bioaccumulative compounds such as polychlorinated biphenyls and DDT in fish collected from the Potomac River and tidal tributaries along the Refuge led to this study. The objective was to determine if there were any indications of pollutant-induced eggshell thinning or evidence of biochemical exposure to contaminants. We examined eggshell thickness and biomarkers of contaminant exposure in livers of embryos collected from the refuge and Coaches Island, a reference location in Chesapeake Bay. There was no evidence of eggshell thinning. Cytochrome P450 activity, measured as ethoxyresomfin-O-dealkylase (EROD) and benzyloxy-resorufin-O-dealkylase (BROD), was not significantly different in embryos from the two colonies. Biochemical indicators of oxidative stress can be reflected as changes in levels of reduced thiols, oxidized glutathione, and thiobarbituric reactive substances (TBARS). Although there were significant differences in the levels of reduced glutathione (GSH) and total thiol (TSH) activities in the embryo livers, there were no statistically significant differences in TBARS, protein-bound sulfhydryls (PBSH), oxidized glutathione (GSSG) and the ratio of GSSG to GSH. In fact, the concentrations of GSH and TSH were higher in the Mason Neck birds relative to Coaches Island. Under conditions of increased oxidative stress at least one or more of the following would be expected: decreased concentrations of reduced thiols (GSH and TSH), increased GSSG, and increased TBARS. In conclusion, we did not detect eggshell thinning or find evidence of a biochemical response to contaminant exposure in the Mason Neck great blue herons.

  11. Developmental toxicity of PCB 126 (3,3',4,4',5-pentachlorobiphenyl) in nestling American kestrels (Falco sparverius)

    USGS Publications Warehouse

    Hoffman, D.J.; Melancon, M.J.; Klein, P.N.; Rice, C.P.; Eisemann, J.D.; Hines, R.K.; Spann, J.W.; Pendleton, G.W.

    1996-01-01

    Planar PCB congeners are embryotoxic and teratogenic to birds including American kestrels. The developmental toxicity of 3,3',4,4',5-pentachlorobiphenyl (PCB 126) was studied in the post-hatching kestrel as a model for the eagle. Nestlings were orally dosed for 10 days with 5 ul/g body weight of corn oil (controls) or the planar PCB 126 at concentrations of 50, 250, or 1000 ng/g body weight. Dosing with 50 ng/g of PCB 126 resulted in a hepatic concentration of 156 ng/g w.w., liver enlargement and mild coagulative necrosis, and over ten-fold increases in hepatic microsomal ethoxyresorufin-O-dealkylase (EROD) and benzyloxyresorufin-O-dealkylase (BROD), and approximately a 5-fold increase in methoxyresorufin-O-dealkylase (MROD). At this dose, mild to moderate lymphoid depletion of the spleen was apparent, and decreased follicle size and content of the thyroid. At 250 ng/g, concentration of PCB 126 in the liver was 380 ng/g with increasing multifocal coagulative necrosis, decreased bone growth, decreased spleen weight with lymphocyte depletion of the spleen and bursa, and degenerative lesions of the thyroid. At 1000 ng/g, the liver concentration was 1098 ng/g, accompanied by decreased bursa weight, decreased hepatic thiol concentration and increased plasma enzyme activities (ALT, AST, and LDH-L) in addition to the previous effects. Highly significant positive correlations were noted between liver concentrations of PCB 126 and the ratio of oxidized to reduced glutathone. These findings indicate that nestling kestrels are more susceptible to PCB 126 toxicity than adults, but less sensitive than embryos, and that planar PCBs are of potential hazard to nestling birds.

  12. Biotransformation and Oxidative Stress Responses in Captive Nile Crocodile (Crocodylus niloticus) Exposed to Organic Contaminants from the Natural Environment in South Africa

    PubMed Central

    Arukwe, Augustine; Røsbak, Randi; Adeogun, Aina O.; Langberg, Håkon A.; Venter, Annette; Myburgh, Jan; Botha, Christo; Benedetti, Maura; Regoli, Francesco

    2015-01-01

    In the present study, the biotransformation and oxidative stress responses in relation to chemical burden in the liver of male and female Nile crocodiles—Crocodylus niloticus—from a commercial crocodile farm passively exposed to various anthropogenic aquatic pollutants was investigated. In general, the data showed that male crocodiles consistently produced higher biotransformation and oxidative stress responses compared to females. Relationships between these responses and concentrations of aliphatic hydrocarbons and polycyclic aromatic hydrocarbons (PAHs) were also observed. Specifically, the catalytic assays for EROD and BROD (not PROD and MROD) showed sex-differences between male and female crocodiles and paralleled immunochemically determined CYP1A and CYP3A protein levels; the relatively similar levels of PAHs in both sexes suggest an estrogen-mediated reduction of this pathway in females. The antioxidant system exhibited higher levels in male crocodiles with slight or significant higher values for catalase (CAT), glutathione reductase (GR), glutathione peroxidases-H2O2 (GPx-H2O2), glutathione peroxidases-Cu (GPx-Cu), total antioxidant capacity towards peroxyl radicals (TOSC-ROO) and hydroxyl radicals (TOSC-HO), total glutathione (GSH) and malondialdehyde (MDA). On the other hand, the activities of acyl-CoA oxidase (AOX) and glutathione S-transferases (GST) were significantly higher in females. Principal component analysis (PCA) produced significant groupings that revealed correlative relationships (both positive and negative) between biotransformation/oxidative stress variables and liver PAHs and aliphatic hydrocarbon burden. The overall results suggest that these captive pre-slaughter crocodiles exhibited adverse exposure responses to anthropogenic aquatic contaminants with potentially relevant effects on key cellular pathways, and these responses may be established as relevant species biomarkers of exposure and effects in this endangered species. PMID

  13. Biotransformation and Oxidative Stress Responses in Captive Nile Crocodile (Crocodylus niloticus) Exposed to Organic Contaminants from the Natural Environment in South Africa.

    PubMed

    Arukwe, Augustine; Røsbak, Randi; Adeogun, Aina O; Langberg, Håkon A; Venter, Annette; Myburgh, Jan; Botha, Christo; Benedetti, Maura; Regoli, Francesco

    2015-01-01

    In the present study, the biotransformation and oxidative stress responses in relation to chemical burden in the liver of male and female Nile crocodiles--Crocodylus niloticus--from a commercial crocodile farm passively exposed to various anthropogenic aquatic pollutants was investigated. In general, the data showed that male crocodiles consistently produced higher biotransformation and oxidative stress responses compared to females. Relationships between these responses and concentrations of aliphatic hydrocarbons and polycyclic aromatic hydrocarbons (PAHs) were also observed. Specifically, the catalytic assays for EROD and BROD (not PROD and MROD) showed sex-differences between male and female crocodiles and paralleled immunochemically determined CYP1A and CYP3A protein levels; the relatively similar levels of PAHs in both sexes suggest an estrogen-mediated reduction of this pathway in females. The antioxidant system exhibited higher levels in male crocodiles with slight or significant higher values for catalase (CAT), glutathione reductase (GR), glutathione peroxidases-H2O2 (GPx-H2O2), glutathione peroxidases-Cu (GPx-Cu), total antioxidant capacity towards peroxyl radicals (TOSC-ROO) and hydroxyl radicals (TOSC-HO), total glutathione (GSH) and malondialdehyde (MDA). On the other hand, the activities of acyl-CoA oxidase (AOX) and glutathione S-transferases (GST) were significantly higher in females. Principal component analysis (PCA) produced significant groupings that revealed correlative relationships (both positive and negative) between biotransformation/oxidative stress variables and liver PAHs and aliphatic hydrocarbon burden. The overall results suggest that these captive pre-slaughter crocodiles exhibited adverse exposure responses to anthropogenic aquatic contaminants with potentially relevant effects on key cellular pathways, and these responses may be established as relevant species biomarkers of exposure and effects in this endangered species. PMID

  14. Catalytic and immunochemical characterization of hepatic microsomal cytochromes P450 in beluga whale (Delphinapterus leucas).

    PubMed

    White, R D; Hahn, M E; Lockhart, W L; Stegeman, J J

    1994-05-01

    Understanding the effects of environmental contaminants on cetaceans and other marine mammals will require information on the biochemistry of xenobiotic metabolism in these species. We characterized the hepatic microsomal cytochrome P450 system in beluga whales (Delphinapterus leucas) from the Canadian Arctic. The content of native P450 averaged 0.203 and 0.319 nmol/mg microsomal protein, cytochrome b5 content averaged 0.199 and 0.236 nmol/mg, and rates of NADPH-cytochrome c reductase were 79 and 76 nmol/min/mg, for females and males respectively. Ethoxyresorufin O-deethylase (EROD), pentoxyresorufin O-depentylase (PROD), and benzo[a]pyrene (BP) hydroxylase (AHH) activities were significantly greater in males than in females, and were highly correlated with one another (r2 between 0.853 and 0.912). HPLC analysis of in vitro BP metabolites revealed benzo-ring (7,8- and 9,10-) dihydrodiols, consistent with activation of this compound, as well as 4,5-dihydrodiol,3-OH-, 7-OH-, and 9-OH-BP and 1,6- and 3,6-quinones. Estradiol 2-hydroxylase activity did not differ between sexes, and rates did not correlate with those of the other activities. Antibodies against scup P450B (an apparent teleost CYP2B) and rat CYP2B1 did not recognize proteins in beluga liver microsomes, but there was a protein detected by antibodies to PB-inducible rabbit CYP2B4. Antibodies to ethanol and ketone-inducible rat CYP2E1 reacted with two proteins in beluga liver microsomes. Antibodies specific to hydrocarbon-inducible CYP1A1 and/or CYP1A2 forms showed a single protein band, apparently more closely related to CYP1A1. The content of CYP1A was fivefold greater in male than in female beluga. CYP1A content was highly correlated with EROD, PROD, and AHH activities, suggesting that this P450 form is a primary catalyst for these reactions in beluga. CYP1A content and activity were highly correlated with the concentrations in blubber of non-ortho and mono-ortho PCB congeners, compounds that induce CYP1A

  15. Hepatic metabolism of ibuprofen in rats under acute hypobaric hypoxia.

    PubMed

    Gola, Shefali; Keshri, Gaurav Km; Gupta, Asheesh

    2013-09-01

    Hypobaric hypoxia induced at high altitude causes a subnormal oxygen concentration in cells which affects the drug metabolic and pharmacokinetic (PK) capacity of the body. The metabolism and PK of drugs like ibuprofen may be impaired under hypoxia and may require a different than usual therapeutic dose regimen to ensure safe therapy. The present investigation was undertaken to evaluate the effect of acute hypobaric hypoxia (AHH) on hepatic metabolism and PK of ibuprofen in rats. Animals were exposed to simulated altitude of 7620 m (∼25,000 ft) for AHH exposure (6 and 24 h) in a decompression chamber and were administrated with single dose of ibuprofen (80 mg/kg body weight, p.o.). The results showed that GST activity was significantly reduced at 6 h (15%) and 24 h (23%) (p<0.05) in hypoxic group as compared to normoxic. A significant increase by 20-24% (p<0.05) in AST level was observed after AHH exposure. LDH activity also exhibited significant increase (p<0.05) after 24h of AHH. A significant down-regulated CYP2C9 level and mild histopathological changes were observed after 24h of AHH. Furthermore, PK variables viz. elimination half-life (T½) and mean residence time (MRT) of ibuprofen exhibited significant increase by 42% and 51% (p<0.05) respectively after 24h of AHH. Thus, results suggest that AHH exposure of 24h significantly affects phase II conjugation pathway, CYP2C9 level, AST level, liver histology and PK parameters. This asserts that AHH can impair disposition of ibuprofen however, it requires further investigation under chronic hypobaric hypoxic conditions.

  16. Latino Access to Preschool Stalls after Earlier Gains: Certain to Harden Achievement Gaps, Erode Workforce Quality. New Journalism on Latino Children

    ERIC Educational Resources Information Center

    Fuller, Bruce; Kim, Anthony Y.

    2011-01-01

    It has been known that quality preschool can boost children's early literacy and social agility, skills valued highly by employers. The returns to preschool appear to be stronger for Latino children, especially those from non-English speaking families, compared with other populations. But newly available data reveal that preschool enrollment…

  17. Increasing the resilience of water and soil resources through successful restoration of eroded landscapes - the case of the Enabered Catchment in Central Tigray, Ethiopia

    NASA Astrophysics Data System (ADS)

    Deribe Zenebe, Haftamu; Finger, David

    2016-04-01

    Integrated land restoration management is part of a rehabilitation approach widely implemented since 2004 in the Tigray region in northern Ethiopia. In this study we assess the effect of physical and biological soil and water conservation practices on erosion and subsequent land degradation in the Enabered watershed, a typical case study in the Tigray region. For this purpose the land uses, the gully dimension and the runoff yields before (2003) and after (2014) land rehabilitation efforts were analyzed. By means of statistical analysis the effects of various restoration measures on runoff and soil loss due to sheet, rill and gully erosion were quantified. The results reveal that large parts of the watershed could be restored and gully formation reversed. The biggest change occurred through the reorganization of homestead areas to cultivated land, accounting for 124.5 ha (18.5% of the entire watershed). The most important changes were achieved by converting bush land to area closures, forest area and plantations. In total these changes accounted for almost 50% of the total area. Furthermore, the entire grazing land and bare land were converted to plantations and area closures. Finally, the observed changes in gully dimensions reveal that restoration activities of the watershed have reduced the soil loss by 86%. Similar effects were determined in the change of the runoff coefficient, which resulted in a decreased by 32.6% of runoff yield. Based on these results the study concludes that the physical and biological soil and water conservation practices led to a successful ecological restoration, increasing the resilience of soil and water resources and finally enhancing the livelihood for the local population.

  18. Determining littoral sediment transport paths adjacent to an eroding carbonate beach through net sediment grain-size trend analysis: Lanikai Beach, Hawaii.

    NASA Astrophysics Data System (ADS)

    Bochicchio, C. J.; Fletcher, C.; Vitousek, S.; Romine, B.; Smith, T.

    2007-12-01

    Identifying long-term trends of sediment transport in coastal environments is a fundamental goal shared by coastal scientists, engineers, and resource managers. Historical photographic analysis and predictive computer models have served as the primary approaches to charactering long-term trends in sediment flux. Net sediment grain-size trend analysis is an empirical, sedimentologically based technique that uses physical sediment samples to identify long-term sediment transport pathways. Originally developed by McLaren and Bowles (1985), net sediment grain-size trend analysis identifies progressive trends in grain-size parameters (mean size, sorting, and skewness) in sediment samples. Ultimately, the results give an indication of long-shore sediment transport, a visualization of individual littoral cells, and a better understanding of sediment processes in the near- shore region. We applied two methodologies put forth by Gao and Collins (1992) and Roux (1994) to 214 samples collected off Lanikai Beach, Hawaii; an excellent example of a coastal environment with chronic beach erosion. The Gao methodology searches point-to-point search for the two trend types used by McLaren. The Roux methodology simultaneously searches between five adjacent points for four trend types. Despite significant differences, similar trends dominate in both sets of results. The Gao methodology produces generalized trends while the Roux methodology shows finer details of sediment transport. Long-shore transport direction is shown to be northward for the majority of the study area, implying a sediment supply to the south. Therefore erosion is instigated if the sediment supply south of Lanikai Beach is cut off. A strong onshore sediment transport trend fails to accrete a beach in an armored section of the southern Lanikai coastline, demonstrating the erosive effect of increased wave refraction from coastal armoring. Results of the sediment trend analyses agree well with tidal current models produced in Delph3D and directional current velocity data for the area.

  19. Changes in eroded material and runoff as affected by rain depth and aggregate slaking in three semi-arid region soils

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Seal formation, runoff and interrill soil erosion are controlled by, among other factors, soil texture, rain properties (kinetic energy and intensity), and aggregate slaking. Previous studies typically reported the total amounts of runoff and soil loss for an entire storm.We examined, at intervals o...

  20. Potential of Radar Imaging and Sounding Methods in Mapping Heavily Eroded Impact Craters: Mapping Some Structural Elements of the Hico Crater, TX

    NASA Technical Reports Server (NTRS)

    Heggy, E.; Horz, F.; Reid, A. M.; Hall, S. A.; Chan, C.

    2004-01-01

    Shuttle Radar Topography Mission (SRTM) and Ground Penetrating Radar (GPR) data collected over an area north of the town of Hico, central Texas, have been used to map disturbances in the surface topography and subsurface stratigraphy. The Radar topography results confirm the presence of multiple rings suggestive of an impact crater. Correlation between the orbital SRTM and on-the-ground GPR field data are affected by different biases related to variations in terrain and vegetation cover. Nevertheless, the correspondence of the two data sets supports the earlier conclusions that a complex, multiple ring impact structure is reflected in the topography of this area. The SRTM data reveal three previously unrecognized rings; with the outermost ring some 5-6 km in diameter. The crater appears to be significantly larger than the size (2.5 km diameter) previously inferred on the basis of aerial images. In addition, the GPR data suggest the presence of subsurface faulting that spatially coincides with the two inner rings of the crater. This suggests that the topographic rings are structurally controlled by faulting.