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Sample records for 7-ethoxyresorufin o-deethylase erod

  1. Ability of fractionated petroleum refinery effluent to elicit cyto- and photocytotoxic responses and to induce 7-ethoxyresorufin-O-deethylase activity in fish cell lines.

    PubMed

    Schirmer, K; Tom, D J; Bols, N C; Sherry, J P

    2001-04-23

    The ability of fractionated petroleum refinery effluent to cause cellular responses in fish cell lines was evaluated. The cellular responses, which included direct and indirect cytotoxicity, photocytotoxicity and induction of 7-ethoxyresorufin-O-deethylase (EROD) activity, may potentially be linked to sublethal effects observed in effluent-exposed fish and fish larvae. In order to be able to quantify cellular responses rapidly, microtitre plates were used along with fluorescent probes. For the quantification of cyto- and photocytotoxicity, the fluorescent probes were alamar Blue and carboxyfluorescein diacetate acetoxymethyl ester (CFDA-AM), which monitor metabolic activity and cell membrane integrity, respectively. EROD activity was measured as the rate of conversion by EROD of the substrate 7-ethoxyresorufin to its fluorescent product, resorufin. Effluent from an Ontario refinery was fractionated into aqueous and particulate phase. As well, a solid phase extract (SPE) was used to prepare concentrated effluent for testing in the cell lines. The effluent was able to elicit all of the responses of interest although significant cyto- and photocytotoxicity required effluent equivalent concentrations above 100% effluent and could only be revealed upon exposure of cells to the SPE concentrated effluent. Based on their retention on C18, the cytotoxicants are likely to be non-polar to moderately polar chemicals. The presence of polar compounds affecting cellular metabolism was indicated by the responses of exposed cells to a 90% aqueous phase effluent. In contrast to cyto- and photocytotoxicity, EROD induction occurred at effluent equivalent concentrations well below 100% effluent and was elicited by the SPE and the particulate fraction thereby suggesting that most EROD-inducers were particle-bound. Among other applications, the described techniques could help to determine the source of causative agents of sublethal effects in the refining process.

  2. 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.

  3. 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.

  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. 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).

  6. Hepatic ethoxyresorufin-O-deethylase induction in the common kingfisher from an electronic waste recycling site.

    PubMed

    Wu, Jiang-Ping; Mo, Ling; Zhi, Hui; Peng, Ying; Tao, Lin; Ren, Zi-He; Luo, Xiao-Jun; Mai, Bi-Xian

    2016-06-01

    The health effects of exposure to electronic waste (e-waste)-derived pollutants are an important issue. The authors explored the association between the hepatic levels of e-waste-derived halogenated contaminants (including polychlorinated biphenyls [PCBs], polybrominated diphenyl ethers [PBDEs], and polybrominated biphenyls [PBBs]) and hepatic ethoxyresorufin-O-deethylase (EROD) activity of the common kingfisher (Alcedo atthis) from an e-waste site and 2 reference sites in South China. The summed concentrations of PCBs, PBDEs, and PBBs ranged from 620 ng/g to 15 000 ng/g, 25 ng/g to 900 ng/g, and 14 ng/g to 49 ng/g wet weight, respectively, in the kingfishers from the e-waste site, and these values were significantly greater (2-3 orders of magnitude) than those obtained at the 2 reference sites. Correspondingly, significant hepatic EROD induction was observed in the kingfishers from the e-waste site compared with the reference sites. The EROD activity was significantly correlated to the levels of most of the PCB and PBDE congeners examined as well as PBB 153, suggesting that EROD induction may be evoked by these e-waste-derived pollutants. Environ Toxicol Chem 2016;35:1594-1599. © 2015 SETAC. PMID:26509239

  7. Hepatic ethoxyresorufin-O-deethylase induction in the common kingfisher from an electronic waste recycling site.

    PubMed

    Wu, Jiang-Ping; Mo, Ling; Zhi, Hui; Peng, Ying; Tao, Lin; Ren, Zi-He; Luo, Xiao-Jun; Mai, Bi-Xian

    2016-06-01

    The health effects of exposure to electronic waste (e-waste)-derived pollutants are an important issue. The authors explored the association between the hepatic levels of e-waste-derived halogenated contaminants (including polychlorinated biphenyls [PCBs], polybrominated diphenyl ethers [PBDEs], and polybrominated biphenyls [PBBs]) and hepatic ethoxyresorufin-O-deethylase (EROD) activity of the common kingfisher (Alcedo atthis) from an e-waste site and 2 reference sites in South China. The summed concentrations of PCBs, PBDEs, and PBBs ranged from 620 ng/g to 15 000 ng/g, 25 ng/g to 900 ng/g, and 14 ng/g to 49 ng/g wet weight, respectively, in the kingfishers from the e-waste site, and these values were significantly greater (2-3 orders of magnitude) than those obtained at the 2 reference sites. Correspondingly, significant hepatic EROD induction was observed in the kingfishers from the e-waste site compared with the reference sites. The EROD activity was significantly correlated to the levels of most of the PCB and PBDE congeners examined as well as PBB 153, suggesting that EROD induction may be evoked by these e-waste-derived pollutants. Environ Toxicol Chem 2016;35:1594-1599. © 2015 SETAC.

  8. 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

  9. Ethoxyresorufin-O-deethylase induction potency of polychlorinated diphenyl ethers in H4IIE rat hepatoma cells

    SciTech Connect

    Koistinen, J.; Sanderson, J.T.; Giesy, J.P.; Nevalainen, T.; Paasivirta, J.

    1996-11-01

    Polychlorinated diphenyl ethers (PCDEs) are structurally similar to polychlorinated biphenyls (PCBs), and some PCDE congeners have been reported to cause toxic responses similar to those caused by some of the non-ortho-substituted PCBs, which are mediated by the aryl hydrocarbon receptor (AhR). Twenty-nine PCDEs were tested for their potency as AhR agonists relative to 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD) by measuring their ability to induce the cytochrome P-450 1A1-associated enzyme activity, ethoxyresorufin-O-deethylase (EROD), in the H4IIE rat hepatoma cell bioassay. All PCDE congeners tested were found to be inactive as EROD inducers except for PCDE 156, which was a weak EROD inducer with a 2,3,7,8-TCDD equivalency factor of about 1.2 {times} 10{sup {minus}5}. During this study the authors determined that small amounts of polychlorinated dibenzofurans (PCDFs) that occurred as impurities in the PCDE preparations were the cause of the apparent EROD induction initially measured in their experiments. Once the PCDF impurities were removed by purification on florisil, little or no activity could be attributed to the PCDEs.

  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. 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

  12. 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

  13. Hepatic ethoxyresorufin-O-deethylase activity and inducibility in wild populations of double-crested cormorants (Phalacrocorax auritus)

    SciTech Connect

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

    1997-07-01

    Microplate fluorometric techniques were used to measure ethoxyresorufin O-deethylase (EROD) activity in hepatic microsomes and primary hepatocyte cultures from individual wild double-crested cormorant (Phalacrocorax auritus) embryos. Embryos were collected in 1993 and 1994 from Humboldt Bay and San Francisco Bay (CA, USA) and a reference site in coastal Oregon (USA). Median microsomal EROD activities in embryos collected from San Francisco Bay (in both 1993 and 1994) and from Humboldt Bay (1994) were four- to eightfold higher than the reference site median. This degree of induction suggests that cormorant embryos in the two California locations were exposed to concentrations of dioxin-like compounds that are at the threshold for toxic effects in this species. Substantial variation in the EROD response in cultured hepatocytes was observed between individuals, populations, and the two bird species tested (cormorants and chickens [Gallus gallus]). Although most of the cormorant individuals displayed a consistent dose-response profile, a few individuals were uninducible, showing no appreciable increase over basal activity with increasing dose of inducer. Composite dose-response curves for two cormorant colonies appeared to be divergent in spite of small sample sizes, indicating that inducibility can also vary at the population level. These observations suggest that considerable variability in pollutant metabolism and sensitivity associated with single enzyme systems may exist within wild populations and species.

  14. 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.

  15. 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.

  16. Ethoxyresorufin-O-deethylase enzyme activities and accumulation of secondary/tertiary lysosomes in rabbitfish Siganus oramin as biomarkers for xenobiotic exposures.

    PubMed

    Fang, James K H; Au, Doris W T; Chan, Alice K Y; So, Leo K Y; Liu, Wenhua; Mok, Helen O L; Yu, Wai-Yin; Wu, Rudolf S S; Shin, Paul K S

    2010-09-15

    The sensitivities of using hepatic and intestinal ethoxyresorufin-O-deethylase (EROD) activities and hepatic accumulation of secondary/tertiary (2 degrees/3 degrees) lysosomes to detect xenobiotic exposures were assessed in the rabbitfish Siganus oramin in a metropolitan harbour, subtropical Hong Kong, over a complete seasonal cycle of one year. Additional information on the body-burden pollutants and physiological indices in S. oramin, and seasonal variables in seawater quality, were extracted from published data and re-analyzed. Under the influences of pollutant cocktail and seasonal factors, neither the hepatic nor intestinal EROD activity was indicative of total polycyclic aromatic hydrocarbons (Sigma PAH), total polychlorinated biphenyls, condition factor and hepatosomatic index (HSI) in S. oramin. However, the relative ratio of hepatic to intestinal EROD activities provided an indication to differentiate the xenobiotic intake route in the fish through diffusion via gills/skin or consumption of contaminated food. In addition, the elevated hepatic accumulation of 2 degrees/3 degrees lysosomes was closely associated with the dominant temporal trends of zinc and Sigma PAH, as well as reduced HSI, in S. oramin. Being minimally influenced by any investigated seasonal factors, the hepatic 2 degrees/3 degrees lysosomes in S. oramin was recommended as an effective biomarker of xenobiotic exposures and toxic effects for use in coastal pollution monitoring programmes.

  17. Temporal trends in ethoxyresorufin-o-deethylase activity of brook trout (Salvelinus fontinalis) fed 2,3,7,8-tetrachlorodibenzo-p-dioxin

    SciTech Connect

    Cormier, S.M.; Millward, M.R.; Mueller, C.; Subramanian, B.; Johnson, R.D.; Tietge, J.E.

    2000-02-01

    Changes in ethoxyresorufin-O-deethylase (EROD) activity were monitored through an extended 6-month dietary exposure to determine the relationship between EROD activity and uptake of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in brook trout, Salvelinus fontinalis. Brook trout were fed labeled TCDD during a 4-week loading phase and an 11-week maintenance phase to achieve whole-body concentrations of 0, 75, 150, 300, 600, and 1,200 pg TCDD/g fish. A spawning phase followed during which no TCDD was introduced. The TCDD had an extended half-life, with maximal levels detected in the late loading-early maintenance phases and 81 d after TCDD had been removed from the diet. Accumulation in liver increased as whole-body target concentration increased but was generally less than half of anticipated whole-body target concentrations. The EROD activity demonstrated a dose-dependent increase. Positive correlations were observed between EROD activity and TCDD body burdens for both males and females. For males, maximal induction was attained early in the maintenance phase and maintained during latter phases. For females, induction was characterized by a biphasic pattern. Maximal induction was attained during late loading-early maintenance, with an attenuated response observed just before spawning. In addition, the induction response was modulated by sex, as induction was lower in females when compared with males. If sexual biases are considered, increased EROD activity may serve as an indicator of level of TCDD exposure and a sublethal predictor of effects of exposure.

  18. Human health risk assessment of soil dioxin/furans contamination and dioxin-like activity determined by ethoxyresorufin-O-deethylase bioassay.

    PubMed

    Man, Yu Bon; Chow, Ka Lai; Wang, Hong Sheng; Sun, Xiao Lin; Wu, Sheng Chun; Cai, Zong Wei; Kang, Yuan; Li, Hui; Zheng, Jin Shu; Giesy, John P; Wong, Ming Hung

    2015-04-01

    The major objective of this study was to evaluate the human health risks of agricultural land use conversion to other purposes in Hong Kong, based on the levels of polychlorinated dibenzo-p-dioxin and polychlorinated dibenzofuran (PCDD/Fs) and determined dioxin-like activity in soil using ethoxyresorufin-O-deethylase (EROD) bioassay. Hazard quotient showed soils of open burning site (OBS) and electronic waste open burning site (EW (OBS)) exert a relatively higher non-cancer risk on adults (50.9 and 8.00) and children (407 and 64.0) via the pathway of accidental ingestion of soil particles than other types of land use. In addition, the levels of 17 PCDD/Fs congeners in OBS and EW (OBS) soils indicated high and moderate (1654 and 260 in one million people) cancer risks through the above pathway. Furthermore, the biologically derived TCDD concentrations (TEQbio) were also significantly correlated to the chemically derived toxic equivalent concentrations of dioxin-like chemicals (TEQcal (sum of chemically derived 2,3,7,8-TeCDD toxic equivalent concentrations (TEQPCDD/F) and chemically derived dioxin-like PAHs toxic equivalent concentrations (TEQPAH)) (r = 0.770, p <0.05). PCDD/Fs (95.4 to 99.9%) were the major stressor to the TEQcal in the soil samples, indicating higher concentrations of PCDD/Fs derived from chemical analyses may reflect a higher potency of inducing EROD activity.

  19. Ethoxyresorufin O-deethylase induction by TCDD, PeCDF and TCDF in ring-necked pheasant and Japanese quail hepatocytes: Time-dependent effects on concentration-response curves.

    PubMed

    Hervé, Jessica C; Crump, Doug; Giesy, John P; Zwiernik, Matthew J; Bursian, Steven J; Kennedy, Sean W

    2010-06-01

    Ethoxyresorufin O-deethylase (EROD) activity was measured in primary cultures of ring-necked pheasant (Phasianuscolchicus) and Japanese quail (Coturnix japonica) embryonic hepatocytes exposed to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), 2,3,4,7,8-pentachlorodibenzofuran (PeCDF) and 2,3,7,8-tetrachlorodibenzofuran (TCDF) for 12, 24, 36 and 48 h. In ring-necked pheasant hepatocytes there was a significant time-dependent increase in the EROD-inducing potency of TCDD, PeCDF and TCDF (i.e. decrease of the EC50). In Japanese quail hepatocytes there was no time-dependent change in the EROD-inducing potency of TCDD, PeCDF and TCDF. There was no time-dependent change in the relative potency of PeCDF and TCDF (i.e. compared to the potency of TCDD) in ring-necked pheasant hepatocytes and of PeCDF in Japanese quail hepatocytes. The results indicate that the relative potencies of these compounds at 24h are representative of their relative potencies between 12 and 48 h. However, in Japanese quail hepatocytes, the relative potency of TCDF decreased in a time-dependent manner (up to 3.6-fold difference). These results suggest that the effect of time on the EROD-inducing potency of TCDD, PeCDF and TCDF in ring-necked pheasant and Japanese quail hepatocytes is compound- and species-specific, but experimental conditions could also be involved in the differences observed.

  20. Exposure of northern leopard frogs in the Green Bay ecosystem to polychlorinated biphenyls, polychlorinated dibenzo-p-dioxins, and polychlorinated dibenzofurans is measured by direct chemistry but not hepatic ethoxyresorufin-O-deethylase activity

    SciTech Connect

    Huang, Y.W.; Karasov, W.H.; Patnode, K.A.; Jefcoate, C.R.

    1999-10-01

    The authors measured concentrations of polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins (PCDDs), and polychlorinated dibenzofurans (PCDFs) in northern leopard frogs collected from the Green Bay ecosystem and explored the catalytic activity of hepatic cytochrome P450-associated monooxygenase (P450 enzyme) as a biomarker for exposure to aryl hydrocarbon receptor (AhR) agonists. The two hypotheses tested were PCH concentrations in northern leopard frogs would be positively correlated with sediment polychlorinated hydrocarbon (PCH) levels in wetland habitats along a contamination gradient and hepatic ethoxyresorufin-O-deethylase (EROD) activity of northern leopard frogs, which is presumably mediated by aryl hydrocarbon receptor (AhR), would be positively correlated with PCH concentrations in frog carcasses from different collection sites. In 1994 and 1995, frogs from seven sites along the lower Fox River and Green Bay, USA, were assayed for hepatic EROD activities and whole carcass concentrations of PCBs, PCDDs, and PCDFs. Tissue total PCB concentrations ranging from 3 to 154 ng/g were significantly correlated with sediment PCB levels. Only one PCDD and two PCDFs at concentrations of 6 to 8 pg/g were found in the frogs collected with frog body weight and was similar among sites except for Peter's Marsh. No significant correlation was found between EROD activity and carcass PCB concentration. This result was consistent with the fact that the frogs collected from the Green Bay ecosystem had relatively low PCB concentrations compared with what was required for induction in the laboratory.

  1. Bioaccumulation of organochlorine contaminants and ethoxyresorufin-O-deethylase activity in southern California round stingrays (Urobatis halleri) exposed to planar aromatic compounds.

    PubMed

    Lyons, Kady; Lavado, Ramon; Schlenk, Daniel; Lowe, Christopher G

    2014-06-01

    While contaminant concentrations have been reported for elasmobranchs around the world, no studies have examined bioaccumulation patterns across male and female age classes. The round stingray (Urobatis halleri) is a local benthic species that forages near areas of high organochlorine contamination and represents a good elasmobranch model. Polychlorinated biphenyls (PCBs), DDT, and chlordanes were measured in juvenile and adult male and female stingrays from areas in southern California, USA (n = 208), and a nearby offshore island, Santa Catalina (n = 34). Both mainland juvenile male and female stingrays showed a significant dilution effect. After maturity, summed contaminant concentrations significantly increased with size for adult males (median 11.1 µg/g lipid wt) and females (5.2 µg/g lipid wt). However, the rate of bioaccumulation was substantially greater in male stingrays than in females, likely a result of the females' ability to offload contaminants to offspring during pregnancy. In addition, males and females showed significant differences in their contaminant profiles, suggesting differential habitat use. Male and female stingrays collected from Santa Catalina Island had significantly lower concentrations (0.51 µg/g and 0.66 µg/g lipid wt, respectively), approximately 5 times less than those of mainland animals. Potential toxicity effects mediated through activation of the aryl hydrocarbon receptor were explored through ethoxyresorufin-O-deethylase (EROD) activity assays. Mainland male stingrays exhibited significantly greater EROD activities than Catalina males (481 pmol/min/mg protein and 55 pmol/min/mg protein, respectively); however, activity levels in female stingrays from both locations were comparable (297 pmol/min/mg protein and 234 pmol/min/mg protein, respectively) and lower than those in mainland males. The results suggest that PCBs and/or other structurally related contaminants may be inducing a biological response

  2. Evaluation of planar halogenated and polycyclic aromatic hydrocarbons in estuarine sediments using ethoxyresorufin-O-deethylase induction of H4IIE cells

    USGS Publications Warehouse

    Gale, R.W.; Long, E.R.; Schwartz, T.R.; Tillitt, D.E.

    2000-01-01

    Polycyclic aromatic hydrocarbons (PAHs) and planar halogenated hydrocarbons (PHHs), including polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs), and biphenyls (PCBs) were determined in fractionated sediment extracts from the Hudson-Raritan estuary and Newark Bay, New Jersey, USA, as part of a comprehensive risk assessment. Contributions of PCDDs/PCDFs, PCBs, and PAHs to the total toxic equivalents (TEQs) were measured using an H4IIE bioassay and calculated from instrumentally determined concentrations using international toxic equivalency factors. The H4IIE TEQs of whole and fractionated extracts were compared to calculated TEQs to investigate the applicability of the bioassay approach for evaluating 7-ethoxyresorufin-O-deethylease induction by PHHs and PAHs present together in complex mixtures. Although 2,3,7,8-tetrachlorodibenzo-p-dioxin contributed from 41 to 79% of the calculated TEQs from PCDDs/PCDFs and planar PCBs in all sediments sampled, the PAH-containing fractions accounted for >80% of the total TEQs determined either instrumentally or by bioassay. Calculated TEQs from PAHs, based on reported toxic equivalency factors for only seven PAHs, were severalfold greater than the bioassay-derived TEQs of PAH-only fractions of the sediment extracts. Significant correlations were observed between bioassay and instrumentally determined toxic equivalents in the more purified fractions but not in fractions only purified by size-exclusion or argentate chromatographies alone.

  3. Evaluation of planar halogenated and polycyclic aromatic hydrocarbons in estuarine sediments using ethoxyresorufin-O-deethylase induction of H4IIE cells

    SciTech Connect

    Gale, R.W.; Long, E.R.; Schwartz, T.R.; Tillitt, D.E.

    2000-05-01

    Polycyclic aromatic hydrocarbons (PAHs) and planar halogenated hydrocarbons (PHHs), including polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs), and biphenyls (PCBs) were determined in fractionated sediment extracts from the Hudson-Raritan estuary and Newark Bay, New Jersey, USA, as part of a comprehensive risk assessment. Contributions of PCDDs/PCDFs, PCBs, and PAHs to the total toxic equivalents (TEQs) were measured using an H4IIE bioassay that calculated from instrumentally determined concentrations using international toxic equivalency factors. The H4IIE TEQs of whole and fractionated extracts were compared to calculated TEQs to investigate the applicability of the bioassay approach for evaluating 7-ethoxyresorufin-O-deethylease induction by PHHs and PAHs present together in complex mixtures. Although 2,3,7,8-tetrachlorodibenzo-p-dioxin contributed from 41 to 79% of the calculated TEQs from PCDDs/PCDFs and planar PCBs in all sediments sampled, the PAH-containing fractions accounted for >80% of the total TEQs determined either instrumentally or by bioassay. Calculated TEQs from PAHs, based on reported toxic equivalency factors for only seven PAHs, were severalfold greater than the bioassay-derived TEQs of PAH-only fractions of the sediment extracts. Significant correlations were observed between bioassay and instrumentally determined toxic equivalents in the more purified fractions but not in fractions only purified by size-exclusion or argentate chromatographies alone.

  4. Microscale In Vitro Assays for the Investigation of Neutral Red Retention and Ethoxyresorufin-O-Deethylase of Biofuels and Fossil Fuels

    PubMed Central

    Bluhm, Kerstin; Brendt, Julia; Mayer, Philipp; Anders, Nico; Schäffer, Andreas; Seiler, Thomas-Benjamin; Hollert, Henner

    2016-01-01

    Only few information on the potential toxic effectiveness of biofuels are available. Due to increasing worldwide demand for energy and fuels during the past decades, biofuels are considered as a promising alternative for fossil fuels in the transport sector. Hence, more information on their hazard potentials are required to understand the toxicological impact of biofuels on the environment. In the German Cluster of Excellence “Tailor-made Fuels from Biomass” design processes for economical, sustainable and environmentally friendly biofuels are investigated. In an unique and interdisciplinary approach, ecotoxicological methods are applied to gain information on potential adverse environmental effects of biofuels at an early phase of their development. In the present study, three potential biofuels, ethyl levulinate, 2-methyltetrahydrofuran and 2-methylfuran were tested. Furthermore, we investigated a fossil gasoline fuel, a fossil diesel fuel and an established biodiesel. Two in vitro bioassays, one for assessing cytotoxicity and one for aryl hydrocarbon receptor agonism, so called dioxin-like activity, as measured by Ethoxyresorufin-O-Deethylase, were applied using the permanent fish liver cell line RTL-W1 (Oncorhynchus mykiss). The special properties of these fuel samples required modifications of the test design. Points that had to be addressed were high substance volatility, material compatibility and low solubility. For testing of gasoline, diesel and biodiesel, water accommodated fractions and a passive dosing approach were tested to address the high hydrophobicity and low solubility of these complex mixtures. Further work has to focus on an improvement of the chemical analyses of the fuel samples to allow a better comparison of any effects of fossil fuels and biofuels. PMID:27684069

  5. 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.

  6. 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.

  7. Chronic hydrocarbon exposure of harlequin ducks in areas affected by the Selendang Ayu oil spill at Unalaska Island, Alaska.

    PubMed

    Flint, Paul L; Schamber, Jason L; Trust, Kimberly A; Miles, A Keith; Henderson, John D; Wilson, Barry W

    2012-12-01

    We evaluated chronic exposure of harlequin ducks (Histrionicus histrionicus) to hydrocarbons associated with the 2004 M/V Selendang Ayu oil spill at Unalaska Island, Alaska. We measured levels of hepatic 7-ethoxyresorufin-O-deethylase activity (EROD) in liver biopsy samples as an indicator of hydrocarbon exposure in three oiled bays and one reference bay in 2005, 2006, and 2008. Median EROD activity in ducks from oiled bays was significantly higher than in the reference bay in seven of nine pairwise comparisons. These results indicated that harlequin ducks were exposed to lingering hydrocarbons more than three years after the spill. PMID:22933448

  8. Chronic hydrocarbon exposure of harlequin ducks in areas affected by the Selendang Ayu oil spill at Unalaska Island, Alaska

    USGS Publications Warehouse

    Flint, Paul L.; Schamber, J.L.; Trust, K.A.; Miles, A.K.; Henderson, J.D.; Wilson, B.W.

    2012-01-01

    We evaluated chronic exposure of harlequin ducks (Histrionicus histrionicus) to hydrocarbons associated with the 2004 M/V Selendang Ayu oil spill at Unalaska Island, Alaska. We measured levels of hepatic 7-ethoxyresorufin-O-deethylase activity (EROD) in liver biopsy samples as an indicator of hydrocarbon exposure in three oiled bays and one reference bay in 2005, 2006, and 2008. Median EROD activity in ducks from oiled bays was significantly higher than in the reference bay in seven of nine pairwise comparisons. These results indicated that harlequin ducks were exposed to lingering hydrocarbons more than three years after the spill.

  9. Chronic hydrocarbon exposure of harlequin ducks in areas affected by the Selendang Ayu oil spill at Unalaska Island, Alaska.

    PubMed

    Flint, Paul L; Schamber, Jason L; Trust, Kimberly A; Miles, A Keith; Henderson, John D; Wilson, Barry W

    2012-12-01

    We evaluated chronic exposure of harlequin ducks (Histrionicus histrionicus) to hydrocarbons associated with the 2004 M/V Selendang Ayu oil spill at Unalaska Island, Alaska. We measured levels of hepatic 7-ethoxyresorufin-O-deethylase activity (EROD) in liver biopsy samples as an indicator of hydrocarbon exposure in three oiled bays and one reference bay in 2005, 2006, and 2008. Median EROD activity in ducks from oiled bays was significantly higher than in the reference bay in seven of nine pairwise comparisons. These results indicated that harlequin ducks were exposed to lingering hydrocarbons more than three years after the spill.

  10. 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

  11. 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.

  12. 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

  13. 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.

  14. 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

  15. 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.

  16. Biomarker responses in mudskipper (Periophthalmus waltoni) from the coastal areas of the Persian Gulf with oil pollution.

    PubMed

    Shirani, Mehrnoosh; Mirvaghefi, Alireza; Farahmand, Hamid; Abdollahi, Mohammad

    2012-11-01

    A suite of 5 different biomarker responses were selected and measured in 3 different phases of detoxification process in mudskipper Periophthalmus waltoni from 3 different stations including Soltani Inlet, Shif Island and Ameri Port in Bushehr coastal area of the Persian Gulf. The selected biomarkers were 7-ethoxyresorufin O-deethylase (EROD), glutathione S-transferase (GST), biliary fluorescent aromatic compounds (FACs), DNA damage using the Comet assay and micronucleus (MN). Spatial variations in biomarker responses were observed in different sites. EROD, GST, FACs, DNA damage and MN were significantly elevated in mudskippers in the most oil impacted site (Soltani inlet). Based on the assessments, bile metabolites, EROD and GST induction appear to be sensitive to polycyclic aromatic hydrocarbons (PAHs) and can be considered as complementary biomarkers; therefore P. waltoni has the potential to be used as a bioindicator in these types of ecosystems.

  17. 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

  18. 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

  19. 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.

  20. 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

  1. 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...

  2. Dioxin-ähnliche Wirkungen durch Grundwasser am Industriestandort Zeitz

    NASA Astrophysics Data System (ADS)

    Schirmer, Kristin; Bopp, Stephanie; Russold, Sandra; Popp, Peter

    Kurzfassung Im Rahmen der Etablierung des Standortes Zeitz (Sachsen-Anhalt) als Referenztestfeld zur Implementierung des Natural-Attenuation-Ansatzes, haben wir Grundwasser auf seine Fähigkeit untersucht, eine Dioxin-ähnliche Wirkung hervorzurufen. Die Dioxin-ähnliche Wirkung ist die Arylhydrocarbon Rezeptor-vermittelte Induktion des Proteinkomplexes Cytochrom CYP1A, welches als 7-Ethoxyresorufin-O-Deethylase (EROD) Enzymaktivität in einer Fischleberzelllinie gemessen wurde. Von 32 Probennahmestellen wiesen sieben eine signifikante EROD-Induktion auf, welche zu einem geringen Teil auf Polyzyklische Aromatische Kohlenwasserstoffe zurückzuführen war. Ein weiterer Teil der EROD-Induktion konnte den Substanzen Benzofuran, Indan und Inden zugesprochen werden, welche hier erstmalig als EROD-Induktoren identifiziert wurden. Alle Probennahmestellen mit signifikanter EROD-Induktion lagen im Anstrom bzw. westlich des früheren Standortes der Benzolanlage in Zeitz, was einen signifikanten Einfluss von Benzol vor allem auf den Transport und das Lösungsverhalten EROD-induzierender Grundwasserkontaminanten vermuten lässt. Insgesamt zeigen diese Untersuchungen, wie eine Kombination von chemischer und biologischer Analytik zu einer deutlich verbesserten Aussagekraft führt und somit zu einer nachhaltigen Überwachung der Qualität von Grundwasser beitragen kann. As part of setting up the test field Zeitz (Saxony-Anhalt, Germany) as a reference site for the implementation of Natural Attenuation as a remediation option, we have investigated groundwater for its ability to cause a dioxin-like response. The dioxin-like response is the aryl hydrocarbon receptor-mediated induction of the protein complex cytochrome CYP1A, which was measured as 7-Ethoxyresorufin-O-deethylase (EROD) enzyme activity in a fish liver cell line. Out of 32 sampling locations, seven showed significant EROD induction, which could be explained, to a minor extent, by the presence of polycyclic aromatic

  3. 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

  4. 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.

  5. 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.

  6. 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.

  7. 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....

  8. 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....

  9. 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....

  10. 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....

  11. 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 ...

  12. 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…

  13. 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.

  14. 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...

  15. 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....

  16. Use of SPMDs and rainbow trout to examine CYP1A1 induction in creosote contaminated mesocosms

    SciTech Connect

    Whyte, J.J.; Karrow, N.; Magdic, S.; Dixon, D.G.; Bols, N.C.; Solomon, K.

    1995-12-31

    Lipid-containing semipermeable membrane devices (SPMDs) and rainbow trout (Oncorhynchus mykiss) were exposed to creosote-dosed mesocosms for a 28 day period. Creosote concentration and exposure period were varied and examined for effects on hepatic and cardiac 7-ethoxyresorufin-O-deethylase (EROD) activity in trout. SPMD uptake rates and selectivity for specific polycyclic aromatic hydrocarbons (PAHs) were also studied. Concentrations of PAHs in SPMDs were compared to PAH concentrations determined in tissues of exposed rainbow trout in order to examine effects of metabolism on PAH burden in living systems. In addition, subfractions of SPMD dialysates and rainbow trout tissue extracts were exposed to the RTL-W1 rainbow trout liver cell line and the H4IIE rat hepatoma cell line. These bioassays were used to measure 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalent concentrations (TECs) of the liver residues as indicated by their relative abilities to induce cytochrome P4501A1 (CYP1A1), measured as EROD activity. This estimates the accumulation by fish of compounds that act through the Ah receptor and are potentially toxic. Hepatic and cardiac EROD activity in the trout were significantly elevated in ponds dosed with creosote as compared to the control pond (ANOVA, p < 0.05) and rose with increasing creosote concentration.

  17. Sensitivity of embryos of chicken, domestic duck, and common eider duck to polychlorinated and non-halogenated aromatic hydrocarbons

    SciTech Connect

    Brunstroem, B.

    1995-12-31

    Embryos of chicken (Gallus domesticus), domestic duck (Anas platyrhynchos), and common eider duck (Somateria mollissima) were exposed in ovo to PCBs and to polycyclic aromatic hydrocarbons. Two coplanar PCBs, 3,3{prime},4,4{prime}-tetrachlorobiphenyl (PCB {number_sign}77) and 3,3{prime},4,4{prime},5-pentachlorobiphenyl (PCB {number_sign}126), were considerably more lethal and potent as inducers of 7-ethoxyresorufin O-deethylase (EROD) in chicken embryos (Gallus domesticus) than in embryos of the other two species. In chicken embryos, these compounds caused edema and eye and beak deformities. An artificial mixture of 18 PAHs which all have been detected in environmental samples, was slightly more toxic to embryos of the domestic duck and the common eider duck than to chicken embryos. The most potent compound in the mixture was benzo(k)fluoranthene. When chicken embryo livers were exposed to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in vitro, EROD was induced by very low concentrations and the EC{sub 50} value obtained was 5 {times} 10{sup {minus}12} M. Livers from embryos of eider ducks and domestic ducks were 2--4 orders of magnitude less responsive to TCDD than chicken embryo livers in terms of EROD induction in vitro.

  18. In vitro interaction of emerging contaminants with the cytochrome p450 system of Mediterranean deep-sea fish.

    PubMed

    Ribalta, Carla; Solé, Montserrat

    2014-10-21

    The interactions of emerging contaminants with the xenobiotic and endogenous metabolizing system of deep-sea fish were compared. The drugs diclofenac, fluoxetine, and gemfibrozil belong to different pharmaceutical classes with diverse mechanistic actions, and the personal care products triclosan, galaxolide, and nonylphenol are representative of antibacterial agents, nitro-musks, and surfactants, respectively. The fish compared are representative of the middle and lower slope of deep-sea habitats. The species were adults of Trachyrynchus scabrus, Mora moro, Cataetix laticeps, and Alepocehalus rostratus. The hepatic metabolic system studied were the activities associated with several cytochrome P450 isoforms (CYPs): 7-ethoxyresorufin-O-deethylase (EROD), benzyloxy-4-[trifluoromethyl]-coumarin-O-debenzyloxylase (BFCOD), and 7-ethoxycoumarin-O-deethylase (ECOD). Results showed differences in baseline activities and sensitivity to chemicals which were species, chemical, and pathway dependent. T. scabrous was the most sensitive species to chemical interactions with the xenobiotic and endogenous metabolizing (EROD and BFCOD) systems, especially in the case of diclofenac interference with BFCOD activity (IC50 = 15.7 ± 2.2 μM). Moreover, T. scabrous and A. rostratus possessed high basal ECOD activity, and this was greatly affected by in vitro exposure to diclofenac in T. scabrous also (IC50 = 6.86 ± 1.4 μM). These results highlight the sensitivity of marine fish to emerging contaminants and propose T. scabrous (middle slope) and A. rostratus (lower slope) as sentinels and the inclusion of ECOD activity as a sensitive biomarker to these exposures. PMID:25225740

  19. 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.

  20. 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.

  1. Biological and chemical determination of dioxin-like compounds in sediments by means of a sediment triad approach in the catchment area of the river Neckar.

    PubMed

    Hollert, Ner; Dürr, Matthias; Olsman, Helena; Halldin, Krister; van Bavel, E; Brack, Werner; Tysklind, Mats; Engwall, Magnus; Braunbeck, Thomas

    2002-10-01

    To evaluate the sediment quality of selected sites in the catchment area of the River Neckar, an integrative assessment approach was used to assess the ecological hazard potential of dioxin-like sediment compounds. The approach is based on 7-ethoxyresorufin-O-deethylase (EROD) induction in embryonic chicken liver culture and comprehensive chemical analyses of polycyclic aromatic hydrocarbons (priority PAHs according to the US Environmental Protection Agency). The majority of the sediment extracts exhibited high potencies as EROD-inducers. In one sediment sample, which was influenced by a sewage treatment plant, a very high concentration of 930 ng bioassay 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) equivalents (bio-TEQs )/g organic carbon could be determined. However, in none of the samples, more than 6% of the EROD-inducing potency could be explained by the PAHs analyzed chemically. Thus, non-analyzed compounds with EROD-inducing potency were present in the extracts. A fractionation of sediment samples according to pH allowed to localize the major part of EROD-inducing compounds in the neutral fractions. However, a significant portion of the EROD induction could also be explained by the acidic fractions. Following the concept of the Sediment Quality Triad according to Chapman, in situ alterations of macrozoobenthos were examined. A comparison of the results predicted by the EROD assay and chemical analyses with alterations in situ, as measured by means of the saprobic index and the ecotoxicological index according to Carmargo, revealed a high ecological relevance of the results of bioassays and chemical analyses for major sites. PMID:12463678

  2. Polybrominated diphenyl ethers and polychlorinated dibenzo-p-dioxins and dibenzofurans in surface dust at an E-waste processing site in Southeast China.

    PubMed

    Leung, Anna O W; Zheng, Jinshu; Yu, Chik Kin; Liu, Wing Keung; Wong, Chris K C; Cai, Zongwei; Wong, Ming H

    2011-07-01

    Surface dust collected from printed circuit board recycling workshop floors, roads, a schoolyard, and an outdoor food market in Guiyu, China, a village intensely involved in e-waste processing, were investigated for levels of polybrominated diphenyl ethers (PBDEs) and polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs). PBDE concentrations in dust from workshop-floors (14,800 ± 5130 ng/g) and on adjacent roads to the workshops (24,900 ± 31,600 ng/g) were highest among the study sites whereas PCDD/F concentrations were highest at the schoolyard (1316 pg/g) and in a workshop (1264 pg/g). Analyses of <2 mm and <53 μm dust particle sizes did not show any significant differences in PBDE concentrations. The cytotoxicity was investigated using two bioassays: 7-ethoxyresorufin O-deethylase (EROD-TEQ) and MTT. EROD-TEQ values ranged from 260 to 432 pg/g, with the highest in dust collected from a street lined with workshops. Using the MTT assay, cytoxicity of dust from the plastic chips drying district in Guiyu was higher than dust from the other sites investigated. This study showed that the primitive recycling of e-waste introduced toxic pollutants into the environment which are potentially harmful to the health of e-waste workers and local residents, especially children, and warrants an urgent investigation into POPs related health impacts.

  3. Contribution of hepatic cytochrome CYP1A and metallothionein mRNA abundance to biomonitoring-A case study with European flounder (Platichthys flesus) from the Gulf of Gdańsk.

    PubMed

    Kopecka-Pilarczyk, Justyna; Schirmer, Kristin

    2016-10-01

    The aim of the research was to explore the contribution of hepatic cytochrome CYP1A and metallothionein (MT) mRNA expression to biological effect monitoring. The study was conducted in the European flounder (Platichthys flesus) from the Gulf of Gdańsk. mRNA abundance was measured using reverse transcriptase polymerase chain reaction (RT-PCR) in liver RNA of fish sampled from three coastal stations and from one offshore station in the inner Gulf. The contribution of the mRNA-based biomarkers to the assessment of the environment was determined in conjunction with a selection of commonly applied biochemical markers: 7-ethoxyresorufin-O-deethylase (EROD), glutathione-S-transferase (GST), catalase (CAT), metallothioneins (MT), fluorescent aromatic compounds (FACs), all measured in the same individual fish. The mRNA biomarkers contributed to the separation between the sampling sites, but no correlations between CYP1A mRNA and EROD nor between MT mRNA and MT proteins were found, which should be attributed to the different levels these biomarkers correspond to and to the differences in factors that may affect them. One case of strong correlation between CYP1A mRNA and FACs was encountered. The overall results of this study suggest that biomarkers measured at the mRNA abundance level constitute a valuable addition to biomonitoring studies by providing additional information and contributing to the differentiation of results. PMID:27276230

  4. Seasonal effect on biomarkers of exposure to petroleum hydrocarbons in fish from Kuwait's marine area.

    PubMed

    Beg, M U; Al-Subiai, S N; Al-Jandal, N; Butt, S A; Beg, K R; Al-Husaini, M

    2015-11-30

    The aquatic biota of the Arabian Gulf deals with exposure to chronic oil pollution, several constituents of which cause induction of Cytochrome P450 1A that serves as a biomarker of AhR ligand exposure. In this study, fluorescent aromatic compounds (FACs) in bile and 7-ethoxyresorufin-o-deethylase (EROD) catalytic activity were determined as a measure of exposure biomarkers in two fish species, yellow fin seabream (Acanthopagrus latus) and tonguesole (Cynoglossus arel) captured from Kuwait Bay and outside the Bay area. FACs in fish bile determined by using fixed-wavelength fluorescence (FF) showed high fluorescence ratios between FF290/335 and FF380/430 indicating predominant exposure to low molecular weight, naphthalene-rich petroleum products (375±91.0 pg ml(-1)). Exposures to benzo(a)pyrene-type high-molecular weight polycyclic aromatic hydrocarbons (PAHs) originating from burnt fuel were also present in appreciable concentration in the bile. The ratio of petrogenic to pyrogenic hydrocarbon was twofold higher in winter compared to summer months in both species. Seasonal effect on EROD was significant in tonguesole in Auha site (P<0.05); whereas seabream resisted seasonal change. Tonguesole is considered to be a suitable bioindicator of oil pollution in Kuwait Bay area.

  5. Effect of chronic exposure to ozone and nitric acid on cytochrome P450 monooxygenase system of rat lung and liver

    SciTech Connect

    Sindhu, R.K.; Mautz, W.J.; Ichiro Fujita, Nai-San Wang; Yutaka, Kikkawa

    1996-03-08

    Male F344/N rats were exposed to 0.15ppm ozone (O{sub 3}) and 50{mu}g/m{sup 3} nitric acid (HNO{sub 3}) vapor alone and in combination for 4h/day 3days/week for a total of 40 weeks. Exposure to HNO{sub 3} vapor alone caused a significant increase of 7-ethoxyresorufin O-deethylase (EROD) activity in the hepatic microsomes (p{le}0.05). Monoclonal cytochrome P450 aA1/1A2 antibody-precipitable EROD activity in the hepatic microsomes was increased by 59% (p{le}0.01) and 40T (p{le}0.05), respectively, in the HNO{sub 3} vapor and {sub 3}+HNO{sub 3} vapor groups. In the pulmonary microsomes, benzphetamine N-demethylase (BPND) activity was increased by 72% (p{le}0.01), 85% (p{le}0.01) and decreased by 15% (p{le}0.01), respectively, by exposure to O{sub 3}, O{sub 3}+HNO{sub 3} and HNO{sub 3} vapor, but was unaffected in the hepatic microsomes.

  6. Chemical and bioanalytical characterization of dioxins in indoor dust in Hong Kong.

    PubMed

    Kang, Yuan; Cheung, Kwai Chung; Cai, Zong Wei; Wong, Ming H

    2011-05-01

    In the present work, air-conditioner filter dust samples collected from commercial office, secondary school, shopping mall, electronic factory and manufacturing plant in Hong Kong were collected for 7-ethoxyresorufin O-deethylase (EROD) assay using a hepatoma cell line (H4IIE) and chemical analysis of dioxins including polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) and PCBs with dioxin-like structure. The result of EROD assay showed that bioassay derived TEQ of 2,3,7,8-TCDD (TEQ(bio)) of dust samples varied from 320 to 730 pg/g. Chemical analyses revealed that chemical derived TEQ of 2,3,7,8-TCDD (TEQ(cal)) of dust samples ranged from 134 to 531 pg/g. In addition, the TEQ(cal) of samples were significantly correlated with TEQ(bio) of samples (R=0.83, P<0.01). The average daily doses (ADDs) of dioxins via indoor dust with the estimated ADDs of dioxins via air and food were compared. The results showed that indoor dust is an important medium of exposure to dioxins. PMID:21300406

  7. Multi-biomarker responses in fishes from two typical marine aquaculture regions of South China.

    PubMed

    He, Xiuting; Nie, Xiangping; Yang, Yufeng; Liu, Xinyu; Pan, Debo; Cheng, Zhang; Liang, Ximei

    2012-11-01

    The impact of typical pollutants upon the fish-farming was assessed by use of a battery of biomarkers in two typical marine aquaculture regions in South China. Biotransformation parameters including 7-ethoxyresorufin-O-deethylase (EROD), aminopyrine N-demethylase (APND), erythromycin N-demethylase (ERND), glutathione-S-transferase (GST) and Malondialdehyde (MDA) were measured in five cultured fish species. Pollutants such as polycyclic aromatic hydrocarbon (PAHs), organochlorinated compounds (OCs), heavy metals and antibiotics (quinolones and sulfonamides) in sediments were characterized. Higher pollutant residue levels were observed in Dapeng Cove. EROD, APND and ERND activities were lower in fish from Dapeng Cove compared with fish from Hailing Island, while it is just on the contrary for GST and MDA. ERND, APND and GST showed sensitivity corresponding to different pollutants. Small fish species seemed to exhibit more sensitive to pollutants. The study further supports usefulness of multi-biomarker approach considering multiple species to define the effects of anthropogenic inputs in marine aquaculture systems.

  8. Seasonal effect on biomarkers of exposure to petroleum hydrocarbons in fish from Kuwait's marine area.

    PubMed

    Beg, M U; Al-Subiai, S N; Al-Jandal, N; Butt, S A; Beg, K R; Al-Husaini, M

    2015-11-30

    The aquatic biota of the Arabian Gulf deals with exposure to chronic oil pollution, several constituents of which cause induction of Cytochrome P450 1A that serves as a biomarker of AhR ligand exposure. In this study, fluorescent aromatic compounds (FACs) in bile and 7-ethoxyresorufin-o-deethylase (EROD) catalytic activity were determined as a measure of exposure biomarkers in two fish species, yellow fin seabream (Acanthopagrus latus) and tonguesole (Cynoglossus arel) captured from Kuwait Bay and outside the Bay area. FACs in fish bile determined by using fixed-wavelength fluorescence (FF) showed high fluorescence ratios between FF290/335 and FF380/430 indicating predominant exposure to low molecular weight, naphthalene-rich petroleum products (375±91.0 pg ml(-1)). Exposures to benzo(a)pyrene-type high-molecular weight polycyclic aromatic hydrocarbons (PAHs) originating from burnt fuel were also present in appreciable concentration in the bile. The ratio of petrogenic to pyrogenic hydrocarbon was twofold higher in winter compared to summer months in both species. Seasonal effect on EROD was significant in tonguesole in Auha site (P<0.05); whereas seabream resisted seasonal change. Tonguesole is considered to be a suitable bioindicator of oil pollution in Kuwait Bay area. PMID:26409815

  9. Biochemical responses in the gills of Meretrix meretrix after exposure to treated municipal effluent.

    PubMed

    Wan, Ru; Meng, Fanping; Fu, Wenchao; Wang, Qun; Su, Enping

    2015-01-01

    The biochemical effects in marine bivalves exposed to increasing concentrations of treated municipal effluent (TME), as discharged into receiving marine waters, are investigated. The effluent was collected from a municipal sewage treatment plant (STP) in Qingdao (China). Meretrix meretrix were exposed to effluent volume ratio (EVR, ratio of effluent volume accounted for tailwater seawater mixture) 0%, 1%, 5%, 10%, and 20% (v/v) TME for 15 days and the following biochemical responses in gills were measured: (1) the activity of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR), and glutathione (GSH) content, and lipid peroxidation levels of malondialdehyde (MDA), as oxidative stress biomarkers; (2) the activity of 7-ethoxyresorufin O-deethylase (EROD) and gluthathione S-transferase (GST), as phase I and phase II conjugation enzymes, respectively; (3) acetylcholinesterase (AChE), as a biomarker of neurotoxicity, and (4) metallothioneins (MTs), as proteins strongly induced by heavy metals. Most of the biochemical indices present high and significant variation frequency (above 50%). There is enhancement in the antioxidant enzymes, EROD, GST, AChE, and MTs, as well as consumption of GSH. The current experimental results suggest that effluent with concentrations less than 20% (v/v) do not cause lipid peroxidation damage. This implies that the activated defense is sufficient to protect the bivalves' gill tissues from cytotoxicity produced by the effluent. Furthermore, GSH, GPx, MTs, and GR are suitable, and sufficiently sensitive, biomarkers to indicate the pollution levels in marine environments receiving such effluent. PMID:25450918

  10. Polybrominated diphenyl ethers and polychlorinated dibenzo-p-dioxins and dibenzofurans in surface dust at an E-waste processing site in Southeast China.

    PubMed

    Leung, Anna O W; Zheng, Jinshu; Yu, Chik Kin; Liu, Wing Keung; Wong, Chris K C; Cai, Zongwei; Wong, Ming H

    2011-07-01

    Surface dust collected from printed circuit board recycling workshop floors, roads, a schoolyard, and an outdoor food market in Guiyu, China, a village intensely involved in e-waste processing, were investigated for levels of polybrominated diphenyl ethers (PBDEs) and polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs). PBDE concentrations in dust from workshop-floors (14,800 ± 5130 ng/g) and on adjacent roads to the workshops (24,900 ± 31,600 ng/g) were highest among the study sites whereas PCDD/F concentrations were highest at the schoolyard (1316 pg/g) and in a workshop (1264 pg/g). Analyses of <2 mm and <53 μm dust particle sizes did not show any significant differences in PBDE concentrations. The cytotoxicity was investigated using two bioassays: 7-ethoxyresorufin O-deethylase (EROD-TEQ) and MTT. EROD-TEQ values ranged from 260 to 432 pg/g, with the highest in dust collected from a street lined with workshops. Using the MTT assay, cytoxicity of dust from the plastic chips drying district in Guiyu was higher than dust from the other sites investigated. This study showed that the primitive recycling of e-waste introduced toxic pollutants into the environment which are potentially harmful to the health of e-waste workers and local residents, especially children, and warrants an urgent investigation into POPs related health impacts. PMID:21639085

  11. 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.

  12. 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.

  13. 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.

  14. Polycyclic aromatic hydrocarbon exposure in Steller's eiders (Polysticta stelleri) and Harlequin ducks (Histronicus histronicus) in the eastern Aleutian Islands, Alaska, USA.

    PubMed

    Miles, A Keith; Flint, Paul L; Trust, Kimberley A; Ricca, Mark A; Spring, Sarah E; Arrieta, Daniel E; Hollmen, Tuula; Wilson, Barry W

    2007-12-01

    Seaducks may be affected by harmful levels of polycyclic aromatic hydrocarbons (PAHs) at seaports near the Arctic. As an indicator of exposure to PAHs, we measured hepatic enzyme 7-ethoxyresorufin-O-deethylase activity (EROD) to determine cytochrome P4501A induction in Steller's eiders (Polysticta stelleri) and Harlequin ducks (Histronicus histronicus) from Unalaska, Popof, and Unga Islands (AK, USA) in 2002 and 2003. We measured PAHs and organic contaminants in seaduck prey samples and polychlorinated biphenyl congeners in seaduck blood plasma to determine any relationship to EROD. Using Akaike's information criterion, species and site differences best explained EROD patterns: Activity was higher in Harlequin ducks than in Steller's eiders and higher at industrial than at nonindustrial sites. Site-specific concentrations of PAHs in blue mussels ([Mytilus trossilus] seaduck prey; PAH concentrations higher at Dutch Harbor, Unalaska, than at other sites) also was important in defining EROD patterns. Organochlorine compounds rarely were detected in prey samples. No relationship was found between polychlorinated biphenyl congeners in avian blood and EROD, which further supported inferences derived from Akaike's information criterion. Congeners were highest in seaducks from a nonindustrial or reference site, contrary to PAH patterns. To assist in interpreting the field study, 15 captive Steller's eiders were dosed with a PAH known to induce cytochrome P4501A. Dosed, captive Steller's eiders had definitive induction, but results indicated that wild Steller's eiders were exposed to PAHs or other inducing compounds at levels greater than those used in laboratory studies. Concentrations of PAHs in blue mussels at or near Dutch Harbor (approximately 1,180-5,980 ng/g) approached those found at highly contaminated sites (approximately 4,100-7,500 ng/g).

  15. Polycyclic aromatic hydrocarbon exposure in Steller's eiders (Polysticta stelleri) and harlequin ducks (Histronicus histronicus) in the Eastern Aleutian Islands, Alaska, USA

    USGS Publications Warehouse

    Miles, A.K.; Flint, P.L.; Trust, K.A.; Ricca, M.A.; Spring, S.E.; Arrieta, D.E.; Hollmen, T.; Wilson, B.W.

    2007-01-01

    Seaducks may be affected by harmful levels of polycyclic aromatic hydrocarbons (PAHs) at seaports near the Arctic. As an indicator of exposure to PAHs, we measured hepatic enzyme 7-ethoxyresorufin-O-deethylase activity (EROD) to determine cytochrome P4501A induction in Steller's eiders (Polysticta stelleri) and Harlequin ducks (Histronicus histronicus) from Unalaska, Popof, and Unga Islands (AK, USA) in 2002 and 2003. We measured PAHs and organic contaminants in seaduck prey samples and polychlorinated biphenyl congeners in seaduck blood plasma to determine any relationship to EROD. Using Akaike's information criterion, species and site differences best explained EROD patterns: Activity was higher in Harlequin ducks than in Steller's eiders and higher at industrial than at nonindustrial sites. Site-specific concentrations of PAHs in blue mussels ([Mytilus trossilus] seaduck prey; PAH concentrations higher at Dutch Harbor, Unalaska, than at other sites) also was important in defining EROD patterns. Organochlorine compounds rarely were detected in prey samples. No relationship was found between polychlorinated biphenyl congeners in avian blood and EROD, which further supported inferences derived from Akaike's information criterion. Congeners were highest in seaducks from a nonindustrial or reference site, contrary to PAH patterns. To assist in interpreting the field study, 15 captive Steller's eiders were dosed with a PAH known to induce cytochrome P4501A. Dosed, captive Steller's eiders had definitive induction, but results indicated that wild Steller's eiders were exposed to PAHs or other inducing compounds at levels greater than those used in laboratory studies. Concentrations of PAHs in blue mussels at or near Dutch Harbor (∼1,180–5,980 ng/g) approached those found at highly contaminated sites (∼4,100–7,500 ng/g).

  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. 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.

  18. 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.

  19. Effects of chronic dietary exposure to a low-dose of Malathion, Aroclor-1254 and 3-methylcholanthrene on three biomarkers in male mice.

    PubMed

    Hackenberger, B K; Jarić, Davorka; Hackenberger, Dubravka; Stepić, Sandra

    2010-12-01

    The aim of this research was to examine the applicability of some chronic toxicological tests in the determination of exposure to xenobiotics present in concentrations below No Observed Adverse Effect Level (NOAEL) and below the detection limit of analytical instruments. In the present experiment tested chemicals (Malathion, Aroclor-1254 and 3-methylcholanthrene (3-MC)) were mixed with wheat grains and given to male mice as feed over a period of 12 months. 7-ethoxyresorufin-O-deethylase (EROD) activity with the 3-MC and Aroclor-1254 treatments reached the peak at 9th month of exposure (26.7 and 42.4 pmol⁻¹ mg(prot)-⁻¹, respectively), while malathion did not have significant influence. Glutathione (GSH) level depletion was highest after three months of exposure. Unexpectedly, acetylcholinesterase (AChE) activity increased after treatment with malathion, an organophosphorous insecticide. In conclusion, low-level concentrations chronically administered exert certain effects on the levels of selected enzymes, e.g. biomarkers.

  20. Effects of benzo(a)pyrene exposure on the antioxidant enzyme activity of scallop Chlamys farreri

    NASA Astrophysics Data System (ADS)

    Pan, Luqing; Ren, Jiayun; Zheng, Debin

    2009-02-01

    Scallop Chlamys farreri was exposed to different concentrations of benzo(a)pyrene (BaP) (0.5 μg/L, 1.0 μg/L, 10.0 μg/L and 50.0 μg/L) for 30 days in seawater. The 7-ethoxyresorufin O-deethylase (EROD) activity was significantly induced, and increased with the increasing BaP concentration. The glutathione-S-transferase (GST), superoxide dismutase (SOD), catalase (CAT), Glutathione peroxidase (GPx) activities increased in short time at low concentration of BaP, and was significantly depressed at high concentrations. Scallop gill was more sensitive to BaP than the digestive gland, and the digestive gland was the main tissue to deal with oxyradicals. The contents of malondialdehyde (MDA) increased with the exposure time and there was a positive correlation (concentration-effect) between the MDA content and the concentration of BaP. The biomarkers determined in this experiment had important roles in detoxification, and showed great potential as biomarkers for oxidative stress. Controlled laboratory experiments designed to simulate field exposure scenarios are particularly useful in ascertaining biomarkers suitable for use with complex contaminant mixtures in the marine environment.

  1. Effects of acetone, acetonitrile, ethanol, methanol and DMSO on cytochrome P450 in rainbow trout (Oncorhynchus mykiss) hepatic microsomes.

    PubMed

    Sakalli, Sidika; Burkina, Viktoriia; Zlabek, Vladimir; Zamaratskaia, Galia

    2015-01-01

    In vitro impacts of five organic solvents on cytochrome P450 (CYP450) enzyme activity were investigated using hepatic microsomes of rainbow trout. The rates of several CYP450-mediated reactions were investigated at solvent concentrations ranging from 0.01% to 3%. The solvents greatly affected all tested reactions. In at least 0.8% ethanol, 2% methanol or acetone, 1% acetonitrile or 3% dimethyl sulfoxide (DMSO), 7-ethoxyresorufin-O-deethylase (EROD) activity decreased and at 3% acetonitrile or ethanol, it was undetected. At 3%, all tested solvents except methanol reduced 7-benzyloxy-4-trifluoromethylcoumarin-O-debenzylase (BFCOD) activity, but at low concentrations of ethanol (2% and lower) or DMSO (1% and lower), it was induced. This was not seen with the inclusion of a pre-incubation step. p-Nitrophenolhydroxylase (PNPH) activity was not affected at concentrations below 1% DMSO, and at 2% acetonitrile it was reduced, as it was above 1% methanol or 0.5% ethanol. Acetone did not affect PNPH activity with or without a pre-incubation step. In general, the degree of inhibition was similar with and without the pre-incubation step. We conclude that the concentration of organic solvent for solubilizing the substrate and inhibitor in in vitro microsomal studies should be minimized.

  2. CYP 450 enzyme induction by chronic oral musk xylene in adult and developing rats.

    PubMed

    Suter-Eichenberger, R; Boelsterli, U A; Conscience-Egli, M; Lichtensteiger, W; Schlumpf, M

    1999-12-20

    Developmental and adult toxicity of musk xylene was studied in Long Evans (LE) rats fed with chow containing musk xylene (MX) in food pellets in concentrations of 1 mg, 10 mg, 33 mg, 100 mg and 1000 mg MX per 1 kg chow corresponding to a daily intake of 0.07-0.08 mg MX/kg up to 70-80 mg MX/kg body weight. Adult male and female rats were MX exposed for a minimum of 10 weeks before mating. Exposure continued throughout pregnancy, birth and lactation. The effects of MX on CYP1A1/1A2 were studied in liver microsomes by EROD (7-ethoxyresorufin-o-deethylase) for CYP1A1 and by MROD (methoxyresorufin-o-demethylase) for CYP1A2 activity and by Western blotting. MX induced these enzymes dose dependently in adult and developing rats at PN (postnatal day) 1 and 14. The lowest effective maternal dose was 2-3 mg MX/kg/day. Western blot data of CYP2B and CYP3A indicated the induction of both P450 enzyme proteins in developing rats at PN 14 at the higher dose of 70-80 mg MX/kg/day. In contrast, upon high MX exposure CYP2B but not CYP3A was found to be induced in adult first generation male and female rats, indicating differential sensitivity to MX in development.

  3. Effect of β-napthoflavone on hepatic cytochrome P4501A activity in the scribbled rabbitfish (Siganus spinus) from tropical Indo-Pacific coral reefs

    PubMed Central

    Kautz, Carmen; Reyes, Andres; Biggs, Jason S.

    2013-01-01

    Several classes of carcinogenic environmental organic pollutants, including polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and dioxins, negatively affect aquatic ecosystems worldwide. Pollutant detection is often difficult and expensive, especially when dealing with complex mixtures and matrices. Biological markers are informative tools to identify living sources that may harbor toxic compounds and areas unsuitable for recreation. Currently, no species have established biomarkers for organopollutant monitoring in Indo-Pacific coral reefs. This study evaluated the time- and dose-dependent induction of the cytochrome P4501A (CYP1A) system in the scribbled rabbitfish, Siganus spinus (Siganidae), as a biomarker for organic pollutant exposures in these environments. Results indicate that S. spinus hepatic CYP1A enzymatic activity and protein level respond dose-, and time-dependently following a single intraperitoneal (IP) injection of the classic aryl hydrocarbon receptor (AHR) agonist, β-napthoflavone (BNF). S. spinus hepatic CYP1A protein and enzymatic activity rose as function of dose during the first two days and slowly returned to levels close to normal after 16 days, as measured using the 7-ethoxyresorufin-O-deethylase (EROD) and the non-competitive enzyme-linked immunosorbent (ELISA) assays, respectively. These findings support use of the inducible CYP1A system of S. spinus as a biomarker for reef fish exposure to coastal marine pollution. Baseline CYP1A expression levels among Guam’s wild S. spinus populations were also measured and compared. PMID:22760666

  4. Biomarkers in the freshwater bivalve Corbicula fluminea confined downstream a domestic landfill leachate discharge.

    PubMed

    de Oliveira, Luciana Fernandes; Santos, Caroline; Dos Reis Martinez, Claudia Bueno

    2016-07-01

    Landfills represent a severe environmental problem mainly due to the generation of leachates, and this study aimed to evaluate sublethal effects of a domestic landfill leachate in the freshwater bivalve Corbicula fluminea. Clams were submitted to in situ tests along a stream, at three sites, representing increasing distances from the leachate discharge (Pq1, Pq2, and Pq3), for 1, 5, and 15 days. The following biomarkers were analyzed in the gills and digestive glands: 7-ethoxyresorufin-O-deethylase (EROD) and glutathione S-transferase (GST) activities, multixenobiotic resistance mechanism (MXR), total antioxidant capacity (TAC), reactive oxygen species (ROS), and lipid peroxidation (LPO). Metallothionein (MT) content was determined in the gills and DNA damage in hemocytes. The mortality rate of animals during in situ tests was reduced as the distance from the leachate discharge source increased. On the other hand, biomarker results showed sublethal effects on C. fluminea confined at all sites of PqS. GST, TAC, ROS, and DNA damage were the most significant biomarkers for this species and should be considered for future monitoring and assessment of freshwater environments located in landfill areas. PMID:27040540

  5. 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.

  6. Methoxychlor suppresses the 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-inducible CYP1A1 expression in murine Hepa-1c1c7 cells.

    PubMed

    Han, Eun Hee; Jeong, Tae Cheon; Jeong, Hye Gwang

    2007-08-01

    Methoxychlor (MXC) is a pesticide that was developed as a replacement for dichlorodiphenyltrichloroethane (DDT). The influence of MXC on CYP1A1 expression or the functions of mouse hepatoma Hepa-1clc7 remain unclear. Cultured Hepa-1c1c7 cells were treated with MXC with or without 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) to assess the role of MXC on CYP1A1 expression. MXC alone did not affect CYP1A1-specific 7-ethoxyresorufin O-deethylase (EROD) activity. In contrast, TCDD-inducible EROD activities were markedly reduced upon concomitant treatment with TCDD and MXC in a concentration-dependent manner. Treatment with ICI 182.780, an estrogen-receptor antagonist, did not affect the suppressive effects of MXC on TCDD-inducible EROD activity. TCDD-inducible CYP1A1 mRNA levels were markedly suppressed upon treatment with TCDD and MXC, and this is consistent with their effects on EROD activity. A transient transfection assay using dioxin-response element (DRE)-linked luciferase and an electrophoretic mobility shift assay revealed that MXC reduced the transformation of the aryl hydrocarbons (Ah) receptor to a form capable of specifically binding to the DRE sequence in the promoter region of the CYP1A1 gene. These results suggest that the downregulation of CYP1A1 gene expression by MXC in Hepa-1c1c7 cells might be an antagonism of the DRE binding potential of the nuclear Ah receptor but is not mediated through the estradiol receptor.

  7. Cytochrome P4501A indices as biomarkers of contaminant exposure: A field study with plaice and flounder

    SciTech Connect

    Eggens, M.; Opperhuizen, A.

    1995-12-31

    Samples of two flatfish species, flounder (Platichthys flesus) and plaice (Pleurnectus platessa), were collected during August/September 1991 and May/June 1992 in the southern North Sea. The induction of hepatic cytochrome P4501A1 (CYP1A) in both species was examined, when exposed to environmental PCBs and PAHs. CYP1A was measured by a semi-quantitative ELISA technique and by the activity of its catalyst, 7-ethoxyresorufin O-deethylase (EROD). In plaice, both hepatic CYP1 protein level and EROD activity were significantly higher at offshore sampling locations than at coastal locations, by a factor of 1.5 to 2. In flounder, which were only collected at coastal locations, the range of values of EROD activity was much greater than in plaice, but the range in CYP1A protein content was comparable in both species. multiple regression analysis of data from plaice and flounder did not show any significant correlation between CYP1A indices, water temperature and contaminant concentrations in fish tissues. CYP1A indices also appeared to be unrelated to food type, as determined by visual screening of fish intestines. It is concluded that the induction of CYP1A in plaice and flounder from the southern North Sea is not related in a simple manner to exposure to PCBs and PAHs. From the point of view-of use as a biomarker, the measurement of CYP1A protein level and EROD activity in plaice and flounder from the open North Sea cannot be applied straightforwardly for monitoring exposure to PCBs and/or PAHs.

  8. Survey of receiving-water environmental impacts associated with discharges from pulp mills; 4: Bioassay-derived 2,3,7,8-tetrachlorodibenzo-p-dioxin toxic equivalent concentration in white sucker (Catostomus commersoni) in relation to biochemical indicators of impact

    SciTech Connect

    Heuvel, M.R. van den; Dixon, D.G. . Dept. of Biology); 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. )

    1994-07-01

    The H411E rat hepatoma bioassay was used to measure 2,3,7,8-tetrachlorodibenzo-p-dioxin toxic equivalent concentrations (TECs) in livers of white sucker (Catostomus commersoni) collected downstream from eight Ontario pulp mills and five reference sites. Subsamples of liver were also chemically analyzed for dioxins and furans. Bioassay-derived TECs were compared with TECs calculated from chemical residues using toxic equivalency factors (TEFs) specifically generated for the H411E cell line. This indicated that the bioassay-derived TECs could be accounted for largely by the additive effect of the dioxin and furan congeners. Seven of the eight examined mills had significantly higher TECs than the corresponding reference locations. The bioassay-derived TECs were highest at mills that used kraft pulping and chlorine bleaching. Although lower than the kraft mills, the thermomechanical (TMP) and sulfite mills also had higher TECs than the adjacent preference locations. The TECs were compared with hepatic 7-ethoxyresorufin-O-deethylase activity (EROD), as well as with concentrations of the plasma steroid hormones 17[beta]-estradiol, 11-ketotestosterone, and testosterone. Significant correlations were found between EROD activity and TECs in both male and female white sucker. The correlation for males was stronger than that for females. Some of the variability in this relationship for females could be explained by a multivariate regression that added 17[beta]-estradiol to the analysis; a strongly negative relationship between 17[beta]-estradiol and EROD activity was superimposed on the positive EROD-TEC relationship. No significant correlations were found between TECs and 11-ketotestosterone in males, 17[beta]-estradiol in females, and gonadosomatic indexes in either sex. There were significant negative correlations between TECs and testosterone in both sexes.

  9. Detection of toxic effects of Cd2+ on different fish species via liver cytochrome P450-dependent monooxygenase activities and FTIR spectroscopy.

    PubMed

    Henczová, Mária; Deér, Aranka Kiss; Komlósi, Viktória; Mink, János

    2006-06-01

    The in vivo and in vitro effects of Cd2+ and the CYP1A inductor beta-naphthoflavone(beta-NF) on the hepatic cytochrome P450 (Cyt 450) monooxygenases were studied in silver carp (Hypophthalmichtys molitrix V.), wels (Silurus glanis L.), and carp (Cyprinus carpio). In vivo treatment of carp with a high dose of Cd2+ (10 mg kg(-1), for 3 days) caused a strong inhibition of 7-ethoxyresorufin-O-deethylase (EROD) and a lower inhibition of 7-ethoxycoumarin-O-deethylase (ECOD) activity. The low-dose cadmium treatment (2 mg kg(-1) Cd2+, for 6+3 days) resulted in 4-fold increase in EROD and a 3-fold increase in ECOD activity. The combined treatment with Cd2+ and beta-NF in both cases led to a loss of EROD inducibility. The silver carp and wels were treated with 10 mg L(-1) Cd2+ for 72 h in water. The Cyt P450 content in the wels liver microsomes was increased significantly after treatment for 48 h, whereas there was only a slight, not significant increase in Cyt P450 content in the silver carp microsomes. While the Cd2+ treatment resulted in inhibition of the CYP1A isoenzymes (EROD and ECOD), the APND (aminopyrene-N-demethylase, CYP2B or CYP3A isoenzyme) activity was increased 3- to 4-fold in both fish species. In vitro experiments of the effect of Cd2+ led to a concentration-dependent inhibition in all three investigated fish species. The ECOD isoenzyme of silver carp was the most sensitive to Cd2+. The lowest concentration of Cd2+ resulted in 50% inhibition. The APND isoenzyme was similarly sensitive to Cd2+ in all three investigated fish species. The most sensitive species was the wels, and the least sensitive were the carp isoenzyme. FTIR spectroscopy confirmed that cadmium caused damage to the protein structure. These results support the enzyme activity measurements measured in vivo and in vitro.

  10. 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

  11. 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). ...

  12. 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...

  13. 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...

  14. 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...

  15. 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 ...

  16. CYP1A andother biomarker responses to effluents from a textile mill in the Volta River (Ghana) using caged tilapia (Oreochromis niloticus) andsediment-exposed mudfish (Clarias anguillaris).

    PubMed

    Gadagbui, B K; Goksrøyr, A

    1996-01-01

    Abstract The ecotoxicological effects of a textile mill effluent were investigated by caging tilapia (Oreochromis niloticus) in the Volta River, Ghana, andby exposing mudfish (Clarias anguillaris) to sediment collected from the same river. Tilapia were caged for 3 weeks at three locations (0.6, 4, and8 km) downstream from the effluent outlet. Mudfish were exposed in the laboratory for 2 weeks to sediment collected from the vicinity of the effluent outlet and8 km downstream. Upstream reference locations 2 km (tilapia) and10.2 km (mudfish) were included. Liver cytochrome P4501A (CYP1A) monooxygenase activity (measured as activity of 7-ethoxyresorufin O-deethylase, EROD, andCYP1A protein level) andtwo conjugation enzymes, UDP-glucuronosyl transferase (UDP-GT) andglutathione Stransferase (GST), were analysed. A distance-related decrease in EROD activity andCYP1A protein level was observed. EROD activity was 21-fold higher in tilapia caged at the site nearest the effluent outlet and25-fold higher in mudfish exposed to sediment collected from the vicinity of the outlet, compared with the respective reference values. UDP-GT andGST levels increased significantly by 70 and27%, respectively, in tilapia while the respective levels in mudfish were 73 and28%, compared with reference values. The results clearly indicate that the textile mill effluent contains some highly potent inducers of biotransformation enzymes. This first assessment of the biological effects of organic pollutants in the Volta River demonstrates the utility of the CYP1A system as a valuable early warning biomarker of industrial effluents andalso as a biomarker to detect exposure of aquatic resources to environmental chemical contamination in tropical waters. PMID:23888992

  17. CYP1A andother biomarker responses to effluents from a textile mill in the Volta River (Ghana) using caged tilapia (Oreochromis niloticus) andsediment-exposed mudfish (Clarias anguillaris).

    PubMed

    Gadagbui, B K; Goksrøyr, A

    1996-01-01

    Abstract The ecotoxicological effects of a textile mill effluent were investigated by caging tilapia (Oreochromis niloticus) in the Volta River, Ghana, andby exposing mudfish (Clarias anguillaris) to sediment collected from the same river. Tilapia were caged for 3 weeks at three locations (0.6, 4, and8 km) downstream from the effluent outlet. Mudfish were exposed in the laboratory for 2 weeks to sediment collected from the vicinity of the effluent outlet and8 km downstream. Upstream reference locations 2 km (tilapia) and10.2 km (mudfish) were included. Liver cytochrome P4501A (CYP1A) monooxygenase activity (measured as activity of 7-ethoxyresorufin O-deethylase, EROD, andCYP1A protein level) andtwo conjugation enzymes, UDP-glucuronosyl transferase (UDP-GT) andglutathione Stransferase (GST), were analysed. A distance-related decrease in EROD activity andCYP1A protein level was observed. EROD activity was 21-fold higher in tilapia caged at the site nearest the effluent outlet and25-fold higher in mudfish exposed to sediment collected from the vicinity of the outlet, compared with the respective reference values. UDP-GT andGST levels increased significantly by 70 and27%, respectively, in tilapia while the respective levels in mudfish were 73 and28%, compared with reference values. The results clearly indicate that the textile mill effluent contains some highly potent inducers of biotransformation enzymes. This first assessment of the biological effects of organic pollutants in the Volta River demonstrates the utility of the CYP1A system as a valuable early warning biomarker of industrial effluents andalso as a biomarker to detect exposure of aquatic resources to environmental chemical contamination in tropical waters.

  18. A comparative approach to 7, 12-dimethylbenz[a]anthracene effects: Metabolism and mutagenesis in mice and fish

    SciTech Connect

    Gallagher, K.; Cline, J.; Burkhart, J.G.; Gundersen, J.L.

    1997-10-01

    A comparative approach was used to examine the effects of exposure to the potent carcinogen 7,12-dimethylbenz[a]anthracene (DMBA) in two divergent sentinel species, mouse and fish, containing a common transgenic reporter, the bacteriophage {O}X174am3. Effects of DMBA were examined using both in vitro and in vivo studies through the analysis of metabolites, cytochrome P450 was examined 72 hours after DMBA dosing using an assay for 7-ethoxyresorufin-o-deethylase (EROD) activity. Fish showed an increasing trend of EROD induction with increasing dose, with the EROD level at the highest dose being significantly greater than corn oil controls and the lowest DMBA dose. DMBA had less of an effect on mouse P450 levels. Metabolites of DMBA in the bile at 12 hours were quantified in both species using HPLC/PDA detection. Bile extracts were enzyme digested to differentiate glucuronide, sulfate and glutathione conjugates. Primary metabolites in mice were 2-hydroxy-7,12-dimethylbenz[a]anthracene, 7-hydroxymethyl-12-methylbenz[a]anthracene. The same metabolites were detected in the fish with the addition of 7,12-bis-hydrodxymethylbenz[a]anthracene. In vitro assays using uninduced and 3-methylcholanthrene-induced mouse microsomes showed no increase over background mutant frequencies of 1-3x10{sup -6} when 0X DNA was incubated with DMBA. In vivo induced mutation was also examined in mice and fish liver. The 1.9 and 19 mg/kg doses of DMBA resulted in a 10-fold increase in mutation frequency over controls in fish. There was a similar increase in mutation frequency at the 19 mg/kg dose in mice. Analysis of the 1.9 mb/kg dosed mice and the replicate variance among treated and control animals is underway.

  19. 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.

  20. Biochemical and Transcriptomic Effects of Herring Gull Egg Extracts from Variably Contaminated Colonies of the Laurentian Great Lakes in Chicken Hepatocytes.

    PubMed

    Crump, Doug; Williams, Kim L; Chiu, Suzanne; Letcher, Robert J; Periard, Luke; Kennedy, Sean W

    2015-08-18

    Determining the effects of complex mixtures of environmental contaminants poses many challenges within the field of ecotoxicology. In this study, graded concentrations of herring gull egg extracts, collected from five Great Lakes breeding colonies with variable burdens of organohalogen contaminants (OHCs), were administered to chicken embryonic hepatocytes to determine effects on 7-ethoxyresorufin-O-deethylase (EROD) activity, porphyrin accumulation, and mRNA expression. EROD activity and porphyrin accumulation permitted the ranking of colonies based on the efficacy of eliciting an aryl hydrocarbon receptor-mediated response. An avian ToxChip polymerase chain reaction (PCR) array provided more exhaustive coverage in terms of potential toxicity pathways being affected, including xenobiotic and lipid metabolism and the thyroid hormone pathway. Herring gull eggs from Channel Shelter Island (CHSH, Lake Huron) and Gull Island (GULL, Lake Michigan) had among the highest OHC burdens, and extracts elicited a biochemical and transcriptomic response greater than that of extracts from the other three, less polluted colonies. For example, EROD EC50 values and porphyrin ECthreshold values were lower for CHSH and GULL extracts than for the other colonies. Extracts from CHSH and GULL altered 15 and 13 of 27 genes on the PCR array compared to no more than eight genes for the less contaminated sites. The combination of a well-established avian in vitro assay, two well-characterized biochemical assays, and the avian ToxChip PCR array permitted the geographical discrimination of variably contaminated herring gull eggs from the Great Lakes. Such high-throughput assays show potential promise as cost-effective tools for determining toxic potencies of complex mixtures in the environment.

  1. Assessment of domestic landfill leachate toxicity to the Asian clam Corbicula fluminea via biomarkers.

    PubMed

    Oliveira, Luciana F; Silva, Sandra M C P; Martinez, Claudia B R

    2014-05-01

    In order to evaluate the effects of domestic landfill leachate to bivalves Corbicula fluminea, clams were exposed to different leachate concentrations (v/v): 2, 3, 6 and 10 percent, corresponding to dilutions observed along a stream that receives this effluent, or only to clean water for comparisons. After 5 and 15 days of exposure the activity of the biotransformation enzymes 7-ethoxyresorufin-O-deethylase (EROD) and glutathione S-transferase (GST), the multixenobiotic resistance mechanism (MXR) and lipid peroxidation (LPO) in gills and digestive gland and metallothionein (MT) content in gills were evaluated. Differences in biomarkers responses were observed between gills and digestive gland, except for MXR that decreased in both tissues of clams exposed to 6 percent for 5 days. EROD activity in gills was reduced in all leachate concentrations after 5 days and only in 2 percent after 15 days exposure, while an EROD increase was observed in digestive gland after 15 days exposure to 6 percent. GST activity increased only in the gills of clams exposed to 10 percent for 5 days. LPO varied between tissues and different conditions. A significant increase in LPO was observed in the gills, after 5 days exposure to 2 and 6 percent, and in digestive gland after 5 and 15 days exposure to 2 and 3 percent. MT content in the gills increased after 15 days exposure to 2 percent. In conclusion, different leachate concentrations tested here caused biochemical changes in C. fluminea, but due to the observed variability in biomarkers responses among leachate concentrations, it was difficult to determine patterns or thresholds concentrations. PMID:24561242

  2. Impact of chemical exposure on the fish Pomatoschistus microps Krøyer (1838) in estuaries of the Portuguese Northwest coast.

    PubMed

    Monteiro, M; Quintaneiro, C; Nogueira, A J A; Morgado, F; Soares, A M V M; Guilhermino, L

    2007-01-01

    Juveniles of the estuarine fish Pomatoschistus microps were collected from autumn 2001 to summer 2002 in five stations along the Portuguese Northwest coast with different types and/or levels of environmental contamination: two reference sites with low levels of contamination (R1 and R2) and three differently impacted areas with higher levels of contamination. UI is located in an estuary under the influence of urban and industrial effluents, AA in a channel that receives intensive agriculture run-off and IE in a highly impacted industrial area. The activity of the enzymes acetylcholinesterase (AChE), lactate dehydrogenase (LDH), 7-ethoxyresorufin O-deethylase (EROD) and glutathione S-transferases (GST) were used as environmental biomarkers on P. microps. A significant seasonality effect on all the enzymatic activities was found, lower levels being registered in winter and spring on AChE, in autumn on LDH, and in winter on GST and EROD. The battery of biomarkers used was capable of discriminating sites with different types and/or levels of contamination, R1 and UI being the highest discriminated (91.7% and 66.7%, respectively). At R1 significantly lower levels of AChE and LDH were found, and EROD was significantly inducted at UI. Furthermore, IE presented higher levels of GST, and R2 and AA an inhibition of AChE in winter and spring. The results indicated that the battery of biomarkers used in this study seems to be a useful tool to distinguish between different types of environmental contamination in estuarine systems, and that P. microps is a suitable species to be used as bioindicator.

  3. 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

  4. 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

  5. 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.

  6. 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.

  7. 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 ...

  8. 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...

  9. 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...

  10. 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...

  11. 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...

  12. 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...

  13. 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...

  14. 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...

  15. 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...

  16. 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...

  17. 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...

  18. 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 ...

  19. 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.

  20. 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

  1. Modulation of 17β-estradiol induced estrogenic responses in male goldfish (Carassius auratus) by benzo[a]pyrene and ketoconazole.

    PubMed

    Yan, Zhenhua; Lu, Guanghua; Ye, Qiuxia; Liu, Jianchao

    2016-05-01

    The aquatic environment is challenged with complex mixtures of chemicals that may interact biochemically with each other in non-target aquatic organisms through a combination of actions, resulting in unpredictable mixture toxicity. This study focuses on the interactive effects of chemicals, including benzo(a)pyrene (BaP) and ketoconazole (KCZ), on 17β-estradiol (E2)-induced estrogenic responses in male goldfish (Carassius auratus). The possible interactions between BaP or KCZ and E2 were investigated on the expression of cytochromeP4501A (CYP1A, biotransformation enzyme) and on its corresponding catalytic activity 7-ethoxyresorufin-O-deethylase (EROD activity), as well as on the expression of CYP19 (steroidogenic enzyme) and E2 bioaccumulation in liver. Exposure to E2 caused a significant increase in estrogenic responses corresponding with the E2 bioaccumulation. When comparing results to the E2 exposure group, co-exposure to BaP resulted in an increase in the cyp1a mRNA expression and its corresponding EROD activity and a marked decrease in the E2 bioaccumulation, but the expression of aromatase was not altered. Conversely, co-treatment with KCZ significantly suppressed the E2-modulated expression of metabolism and synthesis enzymes, which were accompanied by an increase in the E2 bioaccumulation. These data suggest that the modulation of E2-induced estrogenic responses by BaP and KCZ were correlated to the alterations of E2 bioaccumulation in goldfish, leading to a combination of changes in the capacity of biotransformation and steroidogenesis. The complex interactions between chemicals with different modes of actions highlight the need for caution in determining the safety of combined pollution in the aquatic environment. PMID:26825522

  2. Cytochrome P450, acetylcholinesterase and gonadal histology for evaluating contaminant exposure levels in fishes from a highly eutrophic brackish ecosystem: the Orbetello Lagoon, Italy.

    PubMed

    Corsi, I; Mariottini, M; Sensini, C; Lancini, L; Focardi, S

    2003-02-01

    Biochemical markers and ovarian histology were investigated in prespawning females of grass goby (Zosterisessor ophiocephalus) and grey mullet (Mugil cephalus) collected, respectively, in late spring and summer 2000 in four sites of a highly eutrophic brackish ecosystem of central Italy, the Orbetello Lagoon. Exposure to chlorinated and aromatic hydrocarbons was evaluated in fish livers by the somatic liver index (SLI) and by measuring 7-ethoxyresorufin-O-deethylase (EROD) and benzo(a)pyrene monooxygenase (BaPMO) activities. Acetylcholinesterase (AChE) activity was measured in brain and gills to evaluate exposure to organophosphates (OPs) and carbamates (CBs). The gonad somatic index (GSI) was used to confirm ovarian maturation and ovarian histology was investigated as a potential biomarker for environmental effects. Samples from the Western Basin, near a sewage treatment plant (STP) off the town of Orbetello, showed higher SLI values and higher EROD and BaPMO activities than those collected from the Ansedonia Canal (AC) in the Eastern Basin (p<0.05) and respect to those from reference sites: the Albegna River (AR) Delta for grass goby and the Nassa Canal (NC), connected with the sea, for grey mullet both located in the Western Basin as well. Low brain AChE activity was observed in both species from the reference sites (AR and NC) in association with the presence of anomalies in developing oocytes: unexpectedly small in grass goby and irregular disintegrated cytoplasm in grey mullet. The results indicate that the Western Basin is more polluted than the Eastern Basin particularly in the Orbetello where the sewage treatment plant may be a source of aromatic and chlorinated compounds while the Albegna River and the Nassa Canal may be sources of OPs and CBs. PMID:12586116

  3. Hepatic cytochrome P4501A induction in dab (Limanda limanda) after oral dosing with the polychlorinated biphenyl mixture Clophen A40

    SciTech Connect

    Sleiderink, H.M.; Everaarts, J.M.; Boon, J.P.; Goksoeyr, A.

    1995-04-01

    The flatfish dab (Limanda limanda) serves as an indicator species in pollution monitoring programs in the North Sea. The present study investigated the induction response of the monooxygenase system and haematological changes in female dab after multiple administrations of a technical mixture of polychlorinated biphenyls (PCBs). Mature female dab were dosed with 1 mg of the PCB mixture Clophen A40 (Clo A40) in sunflower oil every 6 weeks, with a maximum of three doses per fish. In all PCB-administered groups, levels of cytochrome P4501A (CYPIA) protein, measured with a semi-quantitative ELISA method, and 7-ethoxyresorufin O-deethylase (EROD) activity showed a three- to ninefold induction 14 d after dosing compared with control groups, smaller but also significant increases were observed in total cytochrome P450 ({Sigma} P450) levels. Although the PCB concentrations and the corresponding toxic equivalent (TEQ) value in muscle tissue still increased after administration of the second and third dose of Clo A40, maximum responses of the EROD activity were already reached after the first dose at a TEQ value for chlorinated biphenyls (CB-TEQ) of 2 ng/g lipid. The PCB patterns of liver and muscle tissue of female dab from the central North Sea were found to be virtually identical. Hence, the use of PCB concentrations in muscle as a qualitative model for changes in the liver appears legitimate. Haemoglobin concentrations were elevated after the third dose of Clo A40, whereas haematocrit values and the mean corpuscular haemoglobin concentration (MCHC) between treated and control groups did not differ.

  4. Integrative assessment of biomarker responses in pale chub (Zacco platypus) exposed to copper and benzo[a]pyrene.

    PubMed

    Kim, Woo-Keun; Lee, Sung-Kyu; Choi, Kyungho; Jung, Jinho

    2013-06-01

    Multi-level biomarker responses (molecular/biochemical and histological/physiological levels) were studied to assess the sublethal toxicities of copper (Cu: 1.25, 5, and 20μg/L) and benzo[a]pyrene (BaP: 0.5, 5, and 50μg/L) induced in the freshwater pale chub Zacco platypus. Except for the kidney tissues when exposed to 20μg Cu/L, no significant differences were observed at the histological or physiological levels among the treatment groups. However, various molecular and biochemical responses were observed in Z. platypus, and these responses primarily depended on exposure time. Upon Cu exposure, both DNA single-strand breaks (COMET) and metallothionein (MT) concentration significantly increased after 4 days, whereas there were no significant changes after 14 days of exposure. Both 4 and 14 days of BaP exposure induced significant increases in COMET and 7-ethoxyresorufin-O-deethylase (EROD) activity, but there was no significant difference between them. Additionally, both Cu and BaP induced acetylcholinesterase (AChE) activity only after 14 days of exposure. The current findings demonstrate that the differences in the responses of MT and EROD are associated with each chemical's particular mode of action. Biomarker responses at the molecular and biochemical levels were quantized in terms of the integrated biomarker response (IBR) index to compare the toxicities of Cu and BaP. The IBR values were well correlated with the concentrations of Cu and BaP, and the correlations were enhanced at 4 days of exposure (r(2)=0.849 and 0.945, respectively) compared with 14 days (r(2)=0. 412 and 0.634, respectively). These results suggest that the IBR index may be a useful tool for the integrative quantification of the molecular and biochemical biomarker responses in a short-term exposure to Cu and BaP. PMID:23478165

  5. 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.

  6. 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.

  7. Primary cultured cells as sensitive in vitro model for assessment of toxicants--comparison to hepatocytes and gill epithelia.

    PubMed

    Zhou, Bingsheng; Liu, Chunsheng; Wang, Jingxian; Lam, Paul K S; Wu, Rudolf S S

    2006-11-16

    In an effort to develop cultured cell models for toxicity screening and environmental biomonitoring, we compared primary cultured gill epithelia and hepatocytes from freshwater tilapia (Oreochromis niloticus) to assess their sensitivity to AhR agonist toxicants. Epithelia were cultured on permeable supports (terephthalate membranes, "filters") and bathed on the apical with waterborne toxicants (pseudo in vivo asymmetrical culture conditions). Hepatocytes were cultured in multi-well plates and exposed to toxicants in culture medium. Cytochrome P4501A (measured as 7-Ethoxyresorufin-O-deethylase, EROD) was selected as a biomarker. For cultured gill epithelia, the integrity of the epithelia remained unchanged on exposure to model toxicants, such as 1,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), benzo(a)pyrene B[a]P, polychlorinated biphenyl (PCB) mixture (Aroclor 1254), and polybrominated diphenyl ether (PBDE) mixture (DE71). A good concentration-dependent response of EROD activity was clearly observed in both cultured gill epithelia and hepatocytes. The time-course response of EROD was measured as early as 3h, and was maximal after 6h of exposure to TCDD, B[a]P and Aroclor 1254. The estimated 6h EC50 for TCDD, B[a]P, and Aroclor 1254 was 1.2 x 10(-9), 5.7 x 10(-8) and 6.6 x 10(-6)M. For the cultured hepatocytes, time-course study showed that a significant induction of EROD took place at 18 h, and the maximal induction of EROD was observed at 24h after exposure. The estimated 24h EC50 for TCDD, B[a]P, and Aroclor 1254 was 1.4 x 10(-9), 8.1 x 10(-8) and 7.3 x 10(-6)M. There was no induction or inhibition of EROD in DE71 exposure to both gill epithelia and hepatocytes. The results show that cultured gill epithelia more rapidly induce EROD and are slightly more sensitive than cultured hepatocytes, and could be used as a rapid and sensitive tool for screening chemicals and monitoring environmental AhR agonist toxicants.

  8. 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.

  9. 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.

  10. 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.

  11. 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

  12. 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

  13. 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

  14. 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

  15. 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.

  16. 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

  17. 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...

  18. 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…

  19. 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...

  20. 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)

  1. Gender differences in detoxification metabolism of polycyclic aromatic hydrocarbon (chrysene) in scallop Chlamys farreri during the reproduction period.

    PubMed

    Xiu, Meng; Pan, Luqing; Jin, Qian; Miao, Jingjing

    2015-04-01

    This study aims to investigate the effects of chrysene (CHR) on biotransformation and detoxification responses of mature scallop Chlamys farreri during the reproduction period. Scallops were exposed to 0.2, 0.8 and 3.2 μg/L CHR for 21 days; at day 10 scallops were induced to spawn. At days 1, 3, 6, 10, 11, 15 and 21, enzymatic activities of 7-ethoxyresorufin O-deethylase (EROD) and glutathione-s-transferase (GST), related mRNA expression levels of CYP1A1, GST-pi and P-glycoprotein (P-gp) in digestive glands and CHR bioaccumulation in tissues were examined by separately analyzing male and female scallops. During the pre-spawn period, CHR concentrations of the treated groups in tissues except the hemolymph increased rapidly. Levels of enzymatic activities and related gene expressions were all induced by the exposure to CHR for females and males. GST activity and GST-pi mRNA expression showed a good time- and dose-dependent relationship only in males, and P-gp mRNA expression exhibited a dose-dependent manner in both sexes. During the post-spawn period, spawning caused significant reductions of bioaccumulation in tissues but the gill and hemolymph. Enzymatic activities and related gene expressions were for females significantly depressed at day 21 at 0.8 or 3.2 μg/L CHR. Overall, females accumulated more CHR than males, while males were more sensitive than females to CHR exposure in gene expressions and enzyme activities. P-gp mRNA expression seemed to be a potential biomarker for PAH exposure. These results will offer the information on CHR biotransformation in this species, and ensure the influence of gender and reproductive status on PAH detoxification metabolism.

  2. Combined chemical and toxicological long-term monitoring for AhR agonists with SPMD-based virtual organisms in drinking water Danjiangkou Reservoir, China.

    PubMed

    Wang, Jingxian; Song, Guoqiang; Li, Aimin; Henkelmann, Bernhard; Pfister, Gerd; Tong, Anthony Z; Schramm, Karl-Werner

    2014-08-01

    SPMD-based virtual organisms (VOs) were employed for time-integrating, long-term sampling combined biological and chemical analyses for exposure assessment of hydrophobic organic pollutants (HOPs) in a drinking water reservoir, China. The SPMDs were deployed at four and five sites in the Danjiangkou (DJK) reservoir over two periods of 26 and 31 d to sequester the hydrophobic contaminants in water. The chosen bioassay response for the extracts of the SPMDs, the induction of 7-ethoxyresorufin-o-deethylase (EROD) was assayed using a rat hepatoma cell line (H4IIE). The known aryl hydrocarbon receptor (AhR) agonists PAHs and PCBs were analyzed by HRGC/HRMS instrument. The cause-effect relationship between the observed AhR activities and chemical concentrations of detected AhR agonists was examined. The results show that the extracts from the SPMD samples could induce AhR activity significantly, whereas the chemically derived 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) equivalent (TEQcal) was not correlated with the bioassay-derived TCDD equivalent (TEQbio). The known AhR agonists could only account for 2-10% of the observed AhR responses among which the contribution of PCBs could almost be neglected. Unidentified AhR-active compounds represented a greater proportion of the TCDD equivalent (TCDD-EQ) in SPMD samples from DJK. Based on the first assessment, the VO followed by the combination of chemical and biological analyses emerges as a resource efficient water monitoring device in ecotoxicological assessment for toxicologically relevant compounds which are readily available for uptake by resident aquatic biota in drinking water resources. PMID:24548649

  3. Tumor promoters as inhibitors of apoptosis in rat hepatocytes.

    PubMed

    Schrenk, D; Schmitz, H-J; Bohnenberger, S; Wagner, B; Wörner, W

    2004-04-01

    Multistage carcinogenesis in rat liver is widely used as an experimental model for the study of the critical events in tumor promotion. After an initial treatment with a genotoxic liver carcinogen ('initiation'), subsequent application of certain non-genotoxic agents can lead to the clonal expansion of putative preneoplastic cells ('promotion'). Obviously, the expansion of these clones is correlated with an increased occurrence of benign and malignant liver tumors at later time points. Since both proliferation and apoptosis were reported to be enhanced in putative preneoplastic liver foci, inhibition of apoptosis was suggested to play a critical role in tumor promotion. In rat hepatocytes in primary culture, the liver tumor promoter 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) inhibited apoptosis initiated by treatment of the cultures with UV irradiation but did not affect apoptosis in non-irradiated cultures. The suppression of apoptosis with TCDD coincided with an attenuated increase of the tumor suppressor protein p53 observed upon UV irradiation. Furthermore, TCDD treatment resulted in a marked hyperphosphorylation of p53. The fact that almost identical concentration-response curves were obtained for the phosphorylation of p53 and the induction of cytochrome P450(CYP)1A-catalyzed 7-ethoxyresorufin O-deethylase (EROD) activity indicates that p53 phosphorylation after TCDD treatment is mediated by the aryl hydrocarbon receptor (AhR) signaling cascade. With tumor-promoting 'non-dioxin-like' polychlorinated biphenyls inhibition of UV-induced apoptosis was also observed. A comparative study investigating the effects of various concentrations did not reveal, however, a clear correlation between the suppression of apoptosis and the induction of CYP2B-catalyzed 7-pentoxyresorufin O-dealkylase (PROD) activity. In summary, inhibition of UV-induced apoptosis with liver tumor promoters is observed in rat hepatocytes in culture. Hyperphosphorylation of key proteins of

  4. A new approach of Integrated Health Responses (IHR(s)) modeling for ecological risk/health assessments of an urban stream.

    PubMed

    Kim, Ja-Hyun; Yeom, Dong-Hyuk; An, Kwang-Guk

    2014-08-01

    The objective of this study was to evaluate the ecological health of an urban stream using Integrated Health Responses (IHRs). Water chemistry analysis, habitat health, and ecotoxicity tests were conducted in the stream along with analyses of molecular/biochemical, physiological biomarkers, and population-level responses in indicator species. Chemical stresses, measured as nutrient levels, ionic content and organic matter concentrations were significantly greater (p<0.01) at the downstream than the reference site (RF). The habitat health was largely impacted in the downstream reaches and had a negative relation with the land-use pattern of % urban area. Comet assay, 7-ethoxyresorufin-O-deethylase (EROD), acetylcholinesterase (AChE), and vitellogenin (VTG) were evaluated for low-level biomarker responses on DNA/physiological conditions of target species. The multi-metric fish model (Mm-F) was used to test the community-level response in relation to chemical and physical habitat stresses. The impaired responses of separate biomarker and bioindicator at the downstream sites occurred at all organizations from molecular/biochemical level to community level. Using all biomarkers/bioindicators, the star-plot model of IHRs was developed and then the integrative health/risk assessments were conducted in the urban stream. The reduced values of IHRs occurred in the downstream sites and the impacts were attributed to effluents from wastewater treatment plants (WTPs) and industrial complex. Ecological health impairments, thus, were evident in the urban reach, and reflected the long-term community responses as well as short-term responses of molecular biomarkers. The degradation of the urban stream was mainly due to a combined effect of chemical pollution and physical habitat modifications.

  5. Water exposure assessment of aryl hydrocarbon receptor agonists in Three Gorges Reservoir, China using SPMD-based virtual organisms.

    PubMed

    Wang, Jingxian; Bernhöft, Silke; Pfister, Gerd; Schramm, Karl-Werner

    2014-10-15

    SPMD-based virtual organisms (VOs) were deployed at five to eight sites in the Three Gorges Reservoir (TGR), China for five periods in 2008, 2009 and 2011. The water exposure of aryl hydrocarbon receptor (AhR) agonists was assessed by the VOs. The chosen bioassay response for the extracts of the VOs, the induction of 7-ethoxyresorufin-O-deethylase (EROD) was assayed using a rat hepatoma cell line (H4IIE). The results show that the extracts from the VOs could induce AhR activity significantly, whereas the chemically derived 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) equivalent (TEQcal) accounted for <11% of the observed AhR responses (TEQbio). Unidentified AhR-active compounds represented a greater proportion of the TCDD equivalent in VOs from TGR. High TEQbio value in diluted extract and low TEQbio in concentrated extract of the same sample was observed suggesting potential non-additive effects in the mixture. The levels of AhR agonists in VOs from upstream TGR were in general higher than those from downstream reservoir, indicating urbanization effect on AhR agonist pollution. The temporal variation showed that levels of AhR agonists in 2009 and 2011 were higher than those in 2008, and the potential non-additive effects in the area close to the dam were also obviously higher in 2009 and 2011 than in 2008, indicating big changes in the composition of pollutants in the area after water level reached a maximum of 175 m. Although the aqueous concentration of AhR agonists of 0.8-4.8 pg TCDDL(-1) in TGR was not alarming, the tendency of accumulating high concentration of AhR agonists in VO lipid and existence of possible synergism or antagonism in the water may exhibit a potential hazard to local biota being exposed to AhR agonists.

  6. Gasoline effects on biotransformation and antioxidant defenses of the freshwater fish Prochilodus lineatus.

    PubMed

    Simonato, Juliana D; Fernandes, Marisa Narciso; Martinez, Cláudia B R

    2011-08-01

    Biochemical biomarkers in the Neotropical freshwater fish Prochilodus lineatus were evaluated following acute exposures to the water-soluble fraction of gasoline (WSFG). Fish were exposed to the WSFG diluted to 5% in water (WSFG group) or only to water (Control group) for 6, 24 and 96 h and the gills and liver were removed for the biochemical analyses. Fish exposed to WSFG for 24 and 96 h showed significant increase in the activity of 7-ethoxyresorufin-O-deethylase (EROD) and glutathione-S-transferase (GST) both in liver and gills, pointing toward phase I and phase II biotransformation of the compounds present in the WSFG. The results also indicated the activation of antioxidant defenses in both the liver and gills after fish exposure to WSFG. The liver showed activation of catalase (CAT) and glutathione peroxidase (GPx) after 96 h exposure. An increase in hepatic content of reduced glutathione (GSH) together with decreased glutathione reductase (GR) activity was observed after 24 and 96 h of exposure to WSFG. In the gills, only catalase (CAT) activity augmented after 6 and 24 h of exposure and GSH content increased after 24 h of WSFG exposure. However, in both the organs, activation of the antioxidant defenses was not enough to prevent oxidative damage since they showed lipid peroxidation (LPO) at one of the experimental times: the liver after 6 h and the gills only after 96 h of exposure to WSFG. This may indicate better adaptation of the liver to longer exposures, starting from 24 h. As the gills are the first organ to be exposed to xenobiotics, the antioxidant defenses were triggered immediately upon exposure to WSFG and were able to prevent the occurrence of LPO during the initial times.

  7. Combined chemical and toxicological long-term monitoring for AhR agonists with SPMD-based virtual organisms in drinking water Danjiangkou Reservoir, China.

    PubMed

    Wang, Jingxian; Song, Guoqiang; Li, Aimin; Henkelmann, Bernhard; Pfister, Gerd; Tong, Anthony Z; Schramm, Karl-Werner

    2014-08-01

    SPMD-based virtual organisms (VOs) were employed for time-integrating, long-term sampling combined biological and chemical analyses for exposure assessment of hydrophobic organic pollutants (HOPs) in a drinking water reservoir, China. The SPMDs were deployed at four and five sites in the Danjiangkou (DJK) reservoir over two periods of 26 and 31 d to sequester the hydrophobic contaminants in water. The chosen bioassay response for the extracts of the SPMDs, the induction of 7-ethoxyresorufin-o-deethylase (EROD) was assayed using a rat hepatoma cell line (H4IIE). The known aryl hydrocarbon receptor (AhR) agonists PAHs and PCBs were analyzed by HRGC/HRMS instrument. The cause-effect relationship between the observed AhR activities and chemical concentrations of detected AhR agonists was examined. The results show that the extracts from the SPMD samples could induce AhR activity significantly, whereas the chemically derived 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) equivalent (TEQcal) was not correlated with the bioassay-derived TCDD equivalent (TEQbio). The known AhR agonists could only account for 2-10% of the observed AhR responses among which the contribution of PCBs could almost be neglected. Unidentified AhR-active compounds represented a greater proportion of the TCDD equivalent (TCDD-EQ) in SPMD samples from DJK. Based on the first assessment, the VO followed by the combination of chemical and biological analyses emerges as a resource efficient water monitoring device in ecotoxicological assessment for toxicologically relevant compounds which are readily available for uptake by resident aquatic biota in drinking water resources.

  8. Water exposure assessment of aryl hydrocarbon receptor agonists in Three Gorges Reservoir, China using SPMD-based virtual organisms.

    PubMed

    Wang, Jingxian; Bernhöft, Silke; Pfister, Gerd; Schramm, Karl-Werner

    2014-10-15

    SPMD-based virtual organisms (VOs) were deployed at five to eight sites in the Three Gorges Reservoir (TGR), China for five periods in 2008, 2009 and 2011. The water exposure of aryl hydrocarbon receptor (AhR) agonists was assessed by the VOs. The chosen bioassay response for the extracts of the VOs, the induction of 7-ethoxyresorufin-O-deethylase (EROD) was assayed using a rat hepatoma cell line (H4IIE). The results show that the extracts from the VOs could induce AhR activity significantly, whereas the chemically derived 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) equivalent (TEQcal) accounted for <11% of the observed AhR responses (TEQbio). Unidentified AhR-active compounds represented a greater proportion of the TCDD equivalent in VOs from TGR. High TEQbio value in diluted extract and low TEQbio in concentrated extract of the same sample was observed suggesting potential non-additive effects in the mixture. The levels of AhR agonists in VOs from upstream TGR were in general higher than those from downstream reservoir, indicating urbanization effect on AhR agonist pollution. The temporal variation showed that levels of AhR agonists in 2009 and 2011 were higher than those in 2008, and the potential non-additive effects in the area close to the dam were also obviously higher in 2009 and 2011 than in 2008, indicating big changes in the composition of pollutants in the area after water level reached a maximum of 175 m. Although the aqueous concentration of AhR agonists of 0.8-4.8 pg TCDDL(-1) in TGR was not alarming, the tendency of accumulating high concentration of AhR agonists in VO lipid and existence of possible synergism or antagonism in the water may exhibit a potential hazard to local biota being exposed to AhR agonists. PMID:25058931

  9. 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.

  10. Chemoprotective activity of boldine: modulation of drug-metabolizing enzymes.

    PubMed

    Kubínová, R; Machala, M; Minksová, K; Neca, J; Suchý, V

    2001-03-01

    Possible chemoprotective effects of the naturally occurring alkaloid boldine, a major alkaloid of boldo (Peumus boldus Mol.) leaves and bark, including in vitro modulations of drug-metabolizing enzymes in mouse hepatoma Hepa-1 cell line and mouse hepatic microsomes, were investigated. Boldine manifested inhibition activity on hepatic microsomal CYP1A-dependent 7-ethoxyresorufin O-deethylase and CYP3A-dependent testosterone 6 beta-hydroxylase activities and stimulated glutathione S-transferase activity in Hepa-1 cells. In addition to the known antioxidant activity, boldine could decrease the metabolic activation of other xenobiotics including chemical mutagens. PMID:11265593

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. The expressions of protooncogenes and CYP1A in lungs of rats exposed to sulfur dioxide and benzo(a)pyrene.

    PubMed

    Qin, Guohua; Meng, Ziqiang

    2006-06-01

    Sulfur dioxide (SO2) is a ubiquitous air pollutant, present in low concentrations in the urban air, and in higher concentrations in the working environment. Benzo(a)pyrene (B(a)P), a polycyclic aromatic hydrocarbon, is a ubiquitous environmental contaminant with diverse toxicological effects. To investigate the interactions between SO2 and B(a)P, male Wistar rats were exposed to intratracheally instilled with benzo(a)pyrene (B(a)P; 3 mg) or SO2 (20 ppm) inhalation alone or together. The mRNA of CYP1A1 and 1A2, c-fos, and c-jun and protein levels of c-fos and c-jun were analyzed in lungs using a real-time reverse transcription-polymerase chain reaction (real-time RT-PCR) assay and Western blot analysis, respectively. And 7-ethoxyresorufin O-deethylase (EROD) and methoxyresorufin O-demethylase (MROD) activities were detected. In lungs of rats exposed to SO2 alone, the gene transcription of CYP1A1 and 1A2, the EROD and MROD activities were decreased. Meanwhile, the mRNA and protein levels of c-jun and c-fos were increased significantly. Exposure to B(a)P alone induced CYP1A1, CYP1A2 mRNA levels, the protein levels of c-jun, and the EROD and MROD activities in lungs. However, exposure to B(a)P plus inhaled SO2 neither increased nor decreased CYP1A1/2 mRNA expressions, EROD, and MROD activities in lungs, versus exposure to B(a)P alone. Nevertheless, exposure to B(a)P plus inhaled SO2 increased the mRNA and protein levels of c-jun and c-fos in lungs compared with lungs exposed to SO2 alone. Accordingly, the SO2-induced decreases of CYP1A1/2 might not influence the metabolic activation of B(a)P. However, when B(a)P and SO2 were given in the combinations, one might postulate that a synergistic effect on the expressions of c-fos and c-jun between SO2 and B(a)P, which might be one of the possible mechanisms of combination effects between B(a)P and the air pollutants.

  16. The metabolite 3,4,3',4'-tetrachloroazobenzene (TCAB) exerts a higher ecotoxicity than the parent compounds 3,4-dichloroaniline (3,4-DCA) and propanil.

    PubMed

    Xiao, Hongxia; Kuckelkorn, Jochen; Nüßer, Leonie Katharina; Floehr, Tilman; Hennig, Michael Patrick; Roß-Nickoll, Martina; Schäffer, Andreas; Hollert, Henner

    2016-05-01

    3,4,3',4'-tetrachloroazobenzene (TCAB) is not commercially manufactured but formed as an unwanted by-product in the manufacturing of 3,4-dichloroaniline (3,4-DCA) or metabolized from the degradation of chloranilide herbicides, like propanil. While a considerable amount of research has been done concerning the toxicological and ecotoxicological effects of propanil and 3,4-DCA, limited information is available on TCAB. Our study examined the toxicity of TCAB in comparison to its parent compounds propanil and 3,4-DCA, using a battery of bioassays including in vitro with aryl hydrocarbon receptor (AhR) mediated activity by the 7-ethoxyresorufin-O-deethylase (EROD) assay and micro-EROD, endocrine-disrupting activity with chemically activated luciferase gene expression (CALUX) as well as in vivo with fish embryo toxicity (FET) assays with Danio rerio. Moreover, the quantitative structure activity response (QSAR) concepts were applied to simulate the binding affinity of TCAB to certain human receptors. It was shown that TCAB has a strong binding affinity to the AhR in EROD and micro-EROD induction assay, with the toxic equivalency factor (TEF) of 8.7×10(-4) and 1.2×10(-5), respectively. TCAB presented to be a weak endocrine disrupting compound with a value of estradiol equivalence factor (EEF) of 6.4×10(-9) and dihydrotestosterone equivalency factor (DEF) of 1.1×10(-10). No acute lethal effects of TCAB were discovered in FET test after 96h of exposure. Major sub-lethal effects detected were heart oedema, yolk malformation, as well as absence of blood flow and tail deformation. QSAR modelling suggested an elevated risk to environment, particularly with respect to binding to the AhR. An adverse effect potentially triggering ERβ, mineralocorticoid, glucocorticoid and progesterone receptor activities might be expected. Altogether, the results obtained suggest that TCAB exerts a higher toxicity than both propanil and 3,4-DCA. This should be considered when assessing the

  17. Dioxinlike components in incinerator fly ash: a comparison between chemical analysis data and results from a cell culture bioassay.

    PubMed Central

    Till, M; Behnisch, P; Hagenmaier, H; Bock, K W; Schrenk, D

    1997-01-01

    Potent polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and dioxinlike polychlorinated biphenyls (PCBs) are among the most relevant toxic emissions from incinerators. Induction of cytochrome P450 1A1-catalyzed 7-ethoxyresorufin O-deethylase (EROD) activity in mammalian cell culture (EROD bioassay) is thought to be a selective and sensitive parameter used for the quantification of dioxinlike compounds. Fly ash extracts from municipal waste incinerators (MWI), a crematorium, wood combustors, and a noble metal recycling facility were analyzed in the EROD bioassay using rat hepatocytes in primary culture. Fractions containing 2,3,7,8-substituted PCDDs/PCDFs, dioxinlike PCBs, and 16 major polycyclic aromatic hydrocarbons (PAHs) were isolated from the extract and analyzed by gas chromatography-mass spectrometry (GC-MS) and by the EROD bioassay. It was found that with MWI samples the bioassay of the extract resulted in a two- to fivefold higher estimate of TCDD equivalents (TEQ) than the chemical analysis of PCDDs/PCDFs and PCBs. However, the outcome of both methods was significantly correlated, making the bioassay useful as a rough estimate for the sum of potent PCDDs/PCDFs and dioxinlike PCBs in extracts from MWI fly ash samples and in a fly ash sample from a crematorium. In noble metal recycling facility and wood combustor samples, higher amounts of PAHs were found, contributing to more pronounced differences between the results of both methods. The remaining unexplained inducing potency in fly ash samples probably results from additional dioxinlike components including certain PAHs not analyzed in this study.The hypothesis that emissions from MWI of hitherto unidentified dioxinlike compounds are higher by orders of magnitude than emissions of potent PCDDs/PCDFs and dioxinlike PCBs could not be confirmed. We found no indication for a marked synergistic interaction of dioxinlike fly ash components in the bioassay. Images Figure 1. Figure

  18. 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.

  19. 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.

  20. 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

  1. 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.

  2. 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).

  3. 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.

  4. 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.

  5. 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.

  6. 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

  7. Effect of Fe(2)O(3) on the capacity of benzo(a)pyrene to induce polycyclic aromatic hydrocarbon-metabolizing enzymes in the respiratory tract of Sprague-Dawley rats.

    PubMed

    Garçon, Guillaume; Gosset, Pierre; Zerimech, Farid; Grave-Descampiaux, Béatrice; Shirali, Pirouz

    2004-04-21

    In this work, the question that needs to be answered was whether concurrent exposure to iron oxides and polycyclic aromatic hydrocarbons (PAHs) could affect the induction of PAH-metabolizing enzymes. Male Sprague-Dawley rats were intratracheally instilled with hematite (Fe(2)O(3); 3mg), benzo(a)pyrene (B(a)P; 3mg), or B(a)P (3mg)-coated onto Fe(2)O(3) particles (3mg). Forty-eight hours later, we investigated mRNA expressions of cytochrome p4501a1 (cyp1a1), microsomal epoxide hydrolase (meh), and glutathione-S-transferase-ya and -yc (gst-ya and gst-yc, respectively), protein concentrations of CYP1A1, and 7-ethoxyresorufin O-deethylase (EROD) activities in lungs. Exposure to B(a)P alone or coated-onto Fe(2)O(3) particles induced cyp1a1 gene transcription (P < 0.01) and increased both the CYP1A1 protein levels (P < 0.01) and the EROD activities (P < 0.001). However, in this work, we focused our attention on the potential of Fe(2)O(3) in B(a)P/Fe(2)O(3) mixtures to affect the capacity of B(a)P to induce PAH-metabolizing enzymes. Exposure to B(a)P-coated onto Fe(2)O(3) particles increased meh mRNA expressions (1.15-fold, P < 0.05), CYP1A1 protein concentrations (1.85-fold, P < 0.05), and EROD activities (1.95-fold, P < 0.01), versus exposure to B(a)P alone. Hence, animal short-term exposure to B(a)P-coated onto Fe(2)O(3) particles favored dramatically the induction of PAH-bioactivating enzymes to the detriment of PAH-inactivating enzymes in lungs. Taken together, these results support the hypothesis that the Fe(2)O(3)-induced increase of the metabolic activation of B(a)P might rely on several properties of Fe(2)O(3), including its capacity to enhance the rate of CYP1A1 hemoprotein elaboration. The influence of Fe(2)O(3) in B(a)P/Fe(2)O(3) mixtures on the ability of B(a)P to induce PAH-metabolizing enzymes will also be one of the fundamental ways that Fe(2)O(3) can affect B(a)P carcinogenicity in lungs.

  8. Thyroid hormone-induced changes in the hepatic monooxygenase system, heme oxygenase activity and epoxide hydrolase activity in adult male, female and immature rats.

    PubMed

    Leakey, J E; Mukhtar, H; Fouts, J R; Bend, J R

    1982-07-01

    In 8-day-old rat pups, pretreatment with a single injection of L-triiodothyronine or L-thyroxine decreased hepatic cytochrome P-450 content, aminopyrine N-demethylase activity and epoxide hydrolase activity but increased hepatic microsomal cytochrome c reductase, 7-ethoxyresorufin O-deethylase and heme oxygenase activities without significantly altering UDP-glucuronosyltransferase activity (towards o-aminophenol) or the microsomal yield. In adult rats of either sex such single injections of L-triiodothyronine failed to significantly alter these enzyme activities. However, multiple injections evoked changes similar to those observed in the pups, in all these enzyme activities, except that 7-ethoxyresorufin O-deethylase activity was slightly decreased rather than increased. These findings demonstrate that: (1) The hepatic monooxygenase system in the rat pup is more responsive to thyroid hormones than that in adult. (2) Thyroid hormones can decrease rat liver cytochrome P-450 content and its dependent monooxygenase activity independently of sexual maturity. (3) Thyroid hormones also decrease hepatic epoxide hydrolase activity in both pups and adults. Thus, hyperthyroidism could render the rat pup more susceptible to hepatotoxicity from electrophilic epoxides which utilize microsomal epoxide hydrolase as the major detoxication pathway.

  9. 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

  10. 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...

  11. 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

  12. 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...

  13. 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....

  14. 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....

  15. 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....

  16. 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....

  17. 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....

  18. 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....

  19. 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....

  20. 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....

  1. 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....

  2. 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....

  3. 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...

  4. 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.

  5. 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...

  6. 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...

  7. 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

  8. 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.

  9. 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.

  10. 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.

  11. 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...

  12. Increased exposure of vitamin A by Chrysanthemum morifolium Ramat extract in rat was not via induction of CYP1A1, CYP1A2, and CYP2B1.

    PubMed

    Wang, Ping; Pan, Xian; Chen, Guanming; Li, Jia; Liu, Li; Liu, Xiaodong; Jin, Shi; Xie, Lin; Wang, Guangji

    2012-06-01

    The aim of this study was to investigate the effect of Chrysanthemum morifolium Ramat (CM) extract on the pharmacokinetics of retinol and activities of cytochrome P450s (CYP450s) related to retinoid metabolism. Rats were treated with CM extract for 15 d. Plasma concentrations of retinol were measured following oral administration of retinol (45 mg/kg). Basal levels of retinol and retinoic acid in serum and liver were also measured. 7-Ethoxyresorufin-O-deethylase activity, phenacetin-O-deethylase activity, and 7-pentoxyresorufin-O-deethylase activities were used to assay the activities of CYP1A1, CYP1A2, and CYP2B1 in hepatic microsomes of rats, respectively. Protein expressions of the 3 CYP450s were measured by western blot. Our studies demonstrated that CM extract dose-dependently increased basal level of retinol in serum. In pharmacokinetic experiment, CM extract dose-dependently increased plasma concentrations of retinol after oral administration of retinol to rats treated with CM extract. But activities and expressions of CYP1A1, CYP1A2, and CYP2B1 in hepatic microsomes of rats were also induced by CM extract.

  13. 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

  14. 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

  15. 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

  16. 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.

  17. 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.

  18. Reciprocal inhibiting interactive mechanism between the estrogen receptor and aryl hydrocarbon receptor signaling pathways in goldfish (Carassius auratus) exposed to 17β-estradiol and benzo[a]pyrene.

    PubMed

    Yan, Zhenhua; Lu, Guanghua; He, Junjie

    2012-06-01

    In the aquatic environment, both the estrogen receptor (ER) and aryl hydrocarbon receptor (AhR) responses are established biomarkers for assessing exposure to pollutants. These receptor responses can also be affected by the presence of other classes of pollutants and may result in misinterpretation of existing pollution. In this study, we investigated the interaction between ER-vitellogenin (VTG) and AhR-cytochrome P450 1A (CYP1A) signaling pathways in goldfish (Carassius auratus) after 10 days exposure to pollutants. 17β-Estradiol (E(2)) and benzo[a]pyrene (BaP) were selected as the ER and AhR agonists, respectively. The messenger RNA (mRNA) expression of ER-VTG and AhR-CYP1A in liver was determined using quantitative real-time polymerase chain reaction (QRT-PCR). VTG, endogenous E(2) and 7-ethoxyresorufin-O-deethylase (EROD) were also studied. Exposure to E(2) and BaP alone significantly induced the gene expression of ERα-VTG and AhR2-CYP1A, respectively. Moreover, the obvious expression of related proteins was also observed. However, these inductions were significantly reduced after combined exposure to E(2) and lower concentrations of BaP (20 and 50 μg/L), indicative of a reciprocal inhibiting ER-AhR interaction. However, high concentrations (100 μg/L) of BaP did not affect the E(2)-induced gene expression. Changes in VTG protein were in accordance with the expression of VTG mRNA, and more VTG protein was observed in liver than in serum. The induced endogenous E(2) levels were suppressed by the presence of BaP. While the gene expression of CYP1A showed a concentration-dependent increase, EROD induction exhibited a bell-shaped concentration-response curve. Taken together, these results demonstrate a reciprocal inhibiting mode of ER-AhR interactions and may lead to a possible underestimation of actual exposure.

  19. Effects of 17alpha-ethynylestradiol on hormonal responses and xenobiotic biotransformation system of Atlantic salmon (Salmo salar).

    PubMed

    Mortensen, Anne S; Arukwe, Augustine

    2007-11-30

    Pharmaceuticals are ubiquitous pollutants in the aquatic environment where their potential effects on non-target species like fish has only recently become subject of systematic investigations. In the present study, experiments were undertaken to examine the effects of a synthetic pharmaceutical endocrine disruptor, ethynylestradiol (EE2), given in water at 5 or 50 ng/L and sampled at days 0 (control), 3 and 7 after exposure, on hepatic phase I and II biotransformation and hormonal pathways of juvenile salmon using quantitative (real-time) polymerase chain reaction (qPCR), Vtg ELISA and 7-ethoxyresorufin O-deethylase (EROD) catalytic activity. Our data show that EE2 produced time- and concentration-specific modulation of estrogen receptor isoforms (ERalpha, ERbeta) and androgen receptor-beta (ARbeta). EE2 produced a concentration-specific induction of vitellogenin (Vtg) and zona radiata protein (Zr-protein) at day 3 after exposure. At day 7, Vtg and Zr-protein mRNA (and plasma Vtg protein) expression were significantly decreased in the group given 5 ng EE2/L, compared to dimethyl sulfoxide (DMSO) control group. In the xenobiotic biotransformation pathway, EE2 produced a significant increase of aryl hydrocarbon receptor-alpha (AhRalpha) at day 3 in the group given 5 ng EE2/L and AhRbeta was decreased at the same concentration at day 7. While CYP3A was not significantly affected by EE2 exposure, the CYP1A1, AhR nuclear translocator (Arnt) and AhR repressor (AhRR) mRNA showed an apparent EE2 concentration and time-dependent decrease. The expression of uridine diphosphoglucuronosyl transferase (UGT) and glutathione S-transferase class pi-like (GSTpi-like) mRNA were decreased after exposure to 50ng EE2/L at both day 3 and 7 after exposure. The effect of EE2 on the CYP1A1 gene expressions paralleled effect on EROD and AhRR mRNA, suggesting a direct role of EE2 in controlling cellular detoxification machinery. Interestingly, the carrier vehicle, DMSO produced significant

  20. Biomarkers of contaminant exposure in northern pike (Esox lucius) from the Yukon River Basin, Alaska

    USGS Publications Warehouse

    Hinck, J.E.; Blazer, V.S.; Denslow, N.D.; Myers, M.S.; Gross, T.S.; Tillitt, D.E.

    2007-01-01

    As part of a larger investigation, northern pike (n = 158; Esox lucius) were collected from ten sites in the Yukon River Basin (YRB), Alaska, to document biomarkers and their correlations with organochlorine pesticide (total p,p'-DDT, total chlordane, dieldrin, and toxaphene), total polychlorinated biphenyls (PCBs), and elemental contaminant (arsenic, cadmium, copper, lead, total mercury, selenium, and zinc) concentrations. A suite of biomarkers including somatic indices, hepatic 7-ethoxyresorufin O-deethylase (EROD) activity, vitellogenin concentrations, steroid hormone (17B- ustradiol and 16-kebtestosteront) concentrations, splenic macrophage aggregates (MAs), oocyte atresia, and other microscopic anomalies in various tissues were documented in YRB pike. Mean condition factor (0.50 to 0.68), hepatosomatic index (1.00% to 3.56%), and splenosomatic index (0.09% to 0.18%) were not anomalous at any site nor correlated with any contaminant concentration. Mean EROD activity (0.71 to 17.51 pmol/min/mg protein) was similar to basal activity levels previously measured in pike and was positively correlated with selenium concentrations (r = 0.88, P < 0.01). Vitellogenin concentrations in female (0.09 to 5.32 mg/mL) and male (0.01 mg/mL in male pike from multiple sites indicated exposure to estrogenic compounds. Mean steroid hormone concentrations and percent oocyte atresia were not anomalous in pike from any YRB site. Few site differences were significant for mean MA density (1.86 to 6.42 MA/mm2), size (812 to 1481 ??m2), and tissue occupied (MA-%; 0.24% to 0.75%). A linear regression between MA-% and total PCBs was significant, although PCB concentrations were generally low in YRB pike (???63 ng/g), and MA-% values in female pike (0.24% to 0.54%) were lower than in male pike (0.32% to 0.75%) at similar PCB concentrations. Greater numbers of MAs were found as zinc concentrations increased in YRB female pike, but it is unlikely that this is a causative relationship

  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. 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.

  13. 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

  14. 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

  15. 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.

  16. 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.

  17. 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

  18. 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.

  19. 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

  20. 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.

  1. 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

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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

  7. 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

  8. 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.

  9. 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

  10. 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

  11. 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

  12. 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.

  13. 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

  14. 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

  15. Characterization and profiling of hepatic cytochromes P450 and phase II xenobiotic-metabolizing enzymes in beluga whales (Delphinapterus leucas) from the St. Lawrence River Estuary and the Canadian Arctic.

    PubMed

    McKinney, Melissa A; Arukwe, Augustine; De Guise, Sylvain; Martineau, Daniel; Béland, Pierre; Dallaire, André; Lair, Stéphane; Lebeuf, Michel; Letcher, Robert J

    2004-07-30

    Cytochromes P450 (CYP, phase I) and conjugating (phase II) enzymes can be induced by and influence the toxicokinetics (metabolism) and toxicity of xenobiotic contaminants in exposed organisms. Beluga whale (Delphinapterus leucas) from the endangered St. Lawrence (SL) River Estuary population exhibit deleterious health effects and various severe pathologies that have been associated with contaminant exposure. In contrast, such effects (e.g. reproductive and immunological impairment) are generally less frequent in less exposed populations in the Canadian Arctic (CA). In the present study, opportunistic sampling resulted in the collection immediately after death of liver tissue from a single female neonate SL beluga (SL6) and male and female CA beluga (n=10) from the Arviat region of western Hudson Bay, in addition to sampling of stranded carcasses of male and female SL beluga (n=5) at least 12 h postmortem. We immunologically characterized cross-reactive proteins of hepatic microsomal CYP1A, CYP2B, CYP3A, CYP2E, epoxide hydrolase (EH) and uridine diphosphoglucuronosyl transferase (UDPGT) isozymes. Cross-reactive proteins were found in all SL and CA beluga using anti-rat CYP1A1, anti-rainbow trout CYP3A, anti-human CYP2E1, anti-rabbit EH and anti-human UDPGT1A1 polyclonal antibodies (Abs), whereas faintly cross-reactive CYP2B proteins were only found in SL6 and the CA samples using an anti-rabbit CYP2B1 Ab. In corresponding catalytic activity assessments, only SL6 and all CA beluga microsomal samples exhibited CYP1A-mediated 7-ethoxyresorufin O-deethylase (EROD) activity (51-260 pmol/mg/min), CYP3A-mediated activity (113-899 pmol/mg/min) based on the formation of 6beta-hydroxytestosterone using a testosterone hydroxylase assay, and UDPGT activity (830-4956 pmol/mg/min) based on 1-naphthylglucuronide formation. The marginal cross-reactivity with the anti-CYP2B1 Ab and lack of catalytically measurable hydroxytestosterone isomers associated with CYP2B-type activity in

  16. Overexpression of cerebral and hepatic cytochrome P450s alters behavioral activity of rat offspring following prenatal exposure to lindane

    SciTech Connect

    Johri, Ashu; Yadav, Sanjay; Dhawan, Alok; Parmar, Devendra

    2007-12-15

    Oral administration of different doses (0.0625, 0.125 or 0.25 mg/kg corresponding to 1/1400th, 1/700th or 1/350th of LD{sub 50}) of lindane to the pregnant Wistar rats from gestation days 5 to 21 were found to produce a dose-dependent increase in the activity of cytochrome P450 (CYP)-dependent 7-ethoxyresorufin-O-deethylase (EROD), 7-pentoxyresorufin-O-dealkylase (PROD) and N-nitrosodimethylamine demethylase (NDMA-d) in brain and liver of offspring postnatally at 3 weeks. The increase in the activity of CYP monooxygenases was found to be associated with the increase in the mRNA and protein expression of xenobiotic metabolizing CYP1A, 2B and 2E1 isoenzymes in the brain and liver of offspring. Dose-dependent alterations in the parameters of spontaneous locomotor activity in the offspring postnatally at 3 weeks have suggested that increase in CYP activity may possibly lead to the formation of metabolites to the levels that may be sufficient to alter the behavioral activity of the offspring. Interestingly, the inductive effect on cerebral and hepatic CYPs was found to persist postnatally up to 6 weeks in the offspring at the relatively higher doses (0.125 and 0.25 mg/kg) of lindane and up to 9 weeks at the highest dose (0.25 mg/kg), though the magnitude of induction was less than that observed at 3 weeks. Alterations in the parameters of spontaneous locomotor activity in the offspring postnatally at 6 and 9 weeks, though significant only in the offspring at 3 and 6-week of age, have further indicated that due to the reduced activity of the CYPs during the ontogeny, lindane and its metabolites may not be effectively cleared from the brain. The data suggest that low dose prenatal exposure to the pesticide has the potential to produce overexpression of xenobiotic metabolizing CYPs in brain and liver of the offspring which may account for the behavioral changes observed in the offspring.

  17. Reducing persistent organic pollutants while maintaining long chain omega-3 fatty acid in farmed Atlantic salmon using decontaminated fish oils for an entire production cycle.

    PubMed

    Berntssen, M H G; Olsvik, P A; Torstensen, B E; Julshamn, K; Midtun, T; Goksøyr, A; Johansen, J; Sigholt, T; Joerum, N; Jakobsen, J-V; Lundebye, A-K; Lock, E-J

    2010-09-01

    Oily fish are an important source of health promoting nutrients such as the very long chain marine omega-3 (VLC-n3) fatty acids and simultaneously a source of potentially hazardous contaminants. Fish oils that are used in fish feed are the main source for both contaminants and VLC-n3. Decontamination techniques have recently been developed to effectively remove persistent organic contaminants from fish oils. The aim of the present study was to assess the level of potentially hazardous contaminants and the health beneficial fatty acids in Atlantic salmon reared on novel decontaminated feeds. Atlantic salmon were fed for 18 months (an entire seawater production cycle) on diets based on decontaminated or non-treated (control) fish oils until market size (approximately 5 kg). The level of known notorious persistent organic pollutants (POPs, i.e. dioxins, dioxin-like polychlorinated biphenyls (DL-PCBs), non dioxin-like PCBs, poly brominated diphenyl ethers (PBDE), and organochlorine pesticides), as well as fatty acid composition were analysed in fish oils, the two diets, and Atlantic salmon fillet. The oil decontamination process was a two-step procedure using active carbon and short path distillation. The fillet levels of POPs in market size fish were reduced by 68-85% while the concentration of very long chain omega-3 fatty acids was reduced by 4-7%. No differences in biomarkers of dioxin-like component exposures, such as hepatic gene expression of CYP1A or AhR2B, CYP1A protein expression and 7-ethoxyresorufin O-deethylase (EROD) activity, were observed between salmon raised on normal or decontaminated feeds, thus indicating that the difference in POPs levels were of no biological significance to the fish. Atlantic salmon reared on decontaminated feeds had sum polychlorinated dibenzodioxins/furans (PCDD/Fs) and DL-PCB concentrations that were comparable with terrestrial food products such as beef, while the level of marine omega-3 fatty acids remained as high as for

  18. 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.

  19. 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.

  20. 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.

  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. PMID:26563080

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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

  10. 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

  11. 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.

  12. 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...

  13. 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.

  14. 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

  15. 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.

  16. 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...

  17. 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...

  18. 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.

  19. 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

  20. 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

  1. 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

  2. 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

  3. 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.

  4. 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.

  5. 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

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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

  15. 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.

  16. 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.

  17. 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.

  18. 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

  19. 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.

  20. 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.

  1. 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.

  2. [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.

  3. 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.

  4. 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.

  5. 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

  6. 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.

  7. 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.

  8. 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

  9. 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.

  10. 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.

  11. 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.

  12. 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

  13. Mixed-function oxidase activity in seabirds and its relationship to oil pollution.

    PubMed

    Peakall, D B; Jeffrey, D A; Boersma, D

    1987-01-01

    1. The hepatic activity of epoxide hydrolase, aldrin epoxidase, aminopyrine N-demethylase, 7-ethoxyresorufin O-deethylase, benzo(a)pyrene 3-hydroxylase and UDP glucuronyl transferase was determined in adult herring gulls (Larus argentatus) at various stages of the breeding season. 2. MFO activity was measured for adult Leach's storm-petrels (Oceanodroma leucorhoa), guillemot (Uria aalge) and Atlantic puffins (Fratercula arctica). For most assays the values were highest for the puffin. 3. MFO activity in both nestling and adult Atlantic puffins was determined. The degree of induction caused by a single internal dose of Prudhoe Bay crude oil in adult puffins and that caused by multiple internal doses in nestling puffins was measured. PMID:2890477

  14. Integration of multi-level biomarker responses to cadmium and benzo[k]fluoranthene in the pale chub (Zacco platypus).

    PubMed

    Kim, Woo-Keun; Lee, Sung-Kyu; Park, June-Woo; Choi, Kyungho; Cargo, Jordan; Schlenk, Daniel; Jung, Jinho

    2014-12-01

    The Cd exposure for 14 days significantly increased both the molecular (DNA single-strand breaks) and biochemical (metallothionein concentrations) biomarkers in the freshwater pale chub, Zacco platypus, whereas changes in the histological and physiological biomarker responses were negligible. The BkF exposure for 14 days led to significant increases in the mRNA expression of catalase and superoxide dismutase, 7-ethoxyresorufin-O-deethylase enzymatic activity and DNA single-strand breakage at the molecular and biochemical levels. In addition, exposure to 50μg/L of BkF induced histological alteration in the liver, with significant changes to the liver somatic index and condition factor at the physiological level. The integration of multi-level biomarker responses at the molecular, biochemical and physiological levels was highly correlated with the concentrations of Cd and BkF. PMID:25217733

  15. Environmental contamination and developmental abnormalities in eggs and hatchlings of the common snapping turtle (Chelydra serpentina serpentina) from the Great Lakes-St Lawrence River basin (1989-1991).

    PubMed

    Bishop, C A; Ng, P; Pettit, K E; Kennedy, S W; Stegeman, J J; Norstrom, R J; Brooks, R J

    1998-01-01

    During 1989-1991, we assessed developmental abnormalities in embryos and hatchlings from eggs of the common snapping turtle (Chelydra serpentina serpentina). Eggs were collected and artificially incubated from eight sites in Ontario, Canada and Akwesasne/New York, USA. In eggs from the same clutches we measured 20 organochlorine pesticides, 48 polychlorinated biphenyl (PCBs) congeners including 6 non-ortho PCBs, 8 polychlorinated dibenzodioxins (PCDDs), 14 polychlorinated dibenzofurans (PCDFs) and total mercury. We found a significant increase in abnormal development with increasing polychlorinated aromatic hydrocarbon exposure in eggs, particularly PCDD and PCDF concentrations. In contrast, the risk of abnormality was not significantly higher as toxic equivalent concentrations increased in eggs. We also found significant 7-ethoxyresorufin O-deethylase and Cytochrome P4501A responses in livers of hatchling turtles from Lake Ontario relative to hatchlings from a clean, inland site whereas we did not find any evidence of porphyria in the hatchlings from either site. PMID:15093107

  16. 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...

  17. 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

  18. 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

  19. 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

  20. 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.

  1. 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

  2. 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.

  3. 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

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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).

  10. 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.

  11. 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

  12. 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.

  13. 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.

  14. 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

  15. The ameliorating effects of vitamin E on hepatic antioxidant system and xenobiotic-metabolizing enzymes in fenvalerate-exposed iodine-deficient rats.

    PubMed

    Kocer-Gumusel, Belma; Erkekoglu, Pinar; Caglayan, Aydan; Hincal, Filiz

    2016-01-01

    This study investigated the effects of vitamin E (VE) on hepatic antioxidant system and drug-metabolizing enzymes in fenvalerate (FEN)-exposed iodine-deficient (ID) Wistar rats. ID was produced by perchlorate containing drinking water. VE was introduced by a loading dose of 100 mg/kg/d, i.g. for the first three days in the last week of feeding period; then with a single maintenance dose of 40 mg/kg on the 4th day. During last week, FEN groups (F) received 100 mg/kg/d, i.p. FEN. VE alone did not significantly affect thyroid hormones and antioxidant parameters; however, significantly increased total cytochrome P450 (38%) and cytochrome b5 levels (36%). In all ID groups, plasma thyroid-stimulating hormone (TSH) levels increased markedly, but remained at control level in vitamin E plus FEN receiving iodine-deficient group (IDVF) group. Glutathione peroxidase activity showed marked increases in F (19%) and FEN-exposed iodine-deficient group (IDF, 48%) groups. FEN treatment significantly increased total cytochrome P450 (28%) and thiobarbituric acid reactive substance levels (36%), as well as 7-ethoxyresorufin O-deethylase (120%), 7-penthoxyresorufin O-deethylase (139%) and glutathione S-transferase (15%) activities and decreased total glutathione concentrations (28%) versus control. Overall results suggest that vitamin E has ameliorating effects on the measured parameters in ID and/or FEN exposure.

  16. 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

  17. 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

  18. 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

  19. 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

  20. 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.

  1. 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

  2. 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.

  3. 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

  4. 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"

  5. [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.

  6. 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.

  7. 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

  8. 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

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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

  18. 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

  19. 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.

  20. 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

  1. 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.

  2. 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

  3. 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

  4. 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

  5. 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.

  6. 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.

  7. 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.

  8. 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

  9. 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.

  10. 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.

  11. 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.

  12. Ecotoxicological risks associated with land treatment of petrochemical wastes. II. Effects on hepatic phase I and phase II detoxification enzymes in cotton rats.

    PubMed

    Carlson, Ruth; Wilson, James; Lochmiller, Robert; Janz, David; Schroder, Jackie; Basta, Nicholas

    2003-02-28

    The purpose of this study was to evaluate possible exposure and resultant hepatic effects of petrochemical waste on cotton rats (Sigmodon hispidus) living on landfarmed sites. Male and female cotton rats were collected in summer, fall, and winter from four landfarm sites and four ecologically similar reference sites. Hepatic methoxyresorufin O-deethylase (MROD) activity was significantly induced in male and female rats collected from landfarms compared to rats collected from reference sites. In contrast, changes in ethoxyresorufin O-deethylase (EROD) activity were inconsistent due to season, sex, and treatment variation. A significant decrease in EROD and MROD activity was found in cotton rats held for 48 h prior to sacrifice compared to rats euthanized on the day of capture. These results indicate that when using hepatic EROD and MROD activities as biochemical markers of exposure to aryl hydrocarbon receptor agonists, animals should be euthanized as quickly as possible after capture. The cotton rats collected from one landfarm unit exhibited a pattern of consistent elevation of EROD, MROD, and pent-oxyresorufin O-deethylase (PROD) activity. This unit also had a pattern of elevated CYP1A2 protein expression determined by Western blotting. There were no consistent alterations from contaminant exposure on hepatic glutathione S-transferase (GST) activity, glutathione levels, or CYP1A1 protein. Hepatic EROD and MROD activities varied considerably between seasons and sex of rats. In conclusion, consistent induction of hepatic EROD and MROD activities in cotton rats was found in three out of four sampled landfarm sites compared to the rats collected from the reference sites, indicating exposure to contaminants-likely polyaromatic hydrocarbons.

  13. 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.

  14. 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.

  15. 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

  16. 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

  17. 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.

  18. Effect of prostaglandin F2 alpha on free radical generation, glutathione content and microsomal oxidase activities in rat liver microsomes induced either by ethanol or acetone.

    PubMed

    Sadovnichy, V; Müller, D; Buko, V

    1997-01-01

    We studied the effect of prostaglandin F2 alpha on parameters related to microsomal metabolism (free radical production and lipid peroxidation, glutathione content and activity of microsomal oxidases) after an induction by ethanol or acetone combined with starvation. Long-term ethanol administration led to a significant increase in lipid peroxide formation and NADPH-dependent chemiluminescence amplified by luminol and lucigenin. At the same time hydrogen peroxide production and NADPH-stimulated lipid peroxidation were enhanced although the effect did not reach the level of statistical significance. The concentration of reduced glutathione (GSH) in the liver was decreased 2-fold, whereas oxidized glutathione (GSSG) content remained unaltered. Ethanol intoxication resulted in an increase in 7-ethoxycoumarin-O-deethylase (ECOD), 7-benzyloxycoumarin-O-deethylase (BCOD) and 7-ethoxy-resorufin-O-deethylase (EROD) activities, whereas 7-pentoxyresorufin-O-deethylase (PROD) and ethylmorphin-N-demethylase (EMND) activities were unaltered. The combination of acetone treatment with starvation resulted in a significant increase in lipid and hydrogen peroxide formation, NADPH-dependent lipid peroxidation and chemiluminescence. GSH and GSSG concentration in the liver dramatically decreased 5- and 3-fold, respectively. The acetone treatment led to significant increase in EROD, ECOD, BCOD, PROD and EMND activities. The treatment of ethanol-intoxicated rats with prostaglandin F2 alpha (PGF2 alpha) exerted more pronounced prooxidant effect on liver than action of alcohol itself. At the same time, PGF2 alpha improved most of parameters changed by acetone treatment combined with starvation, decreasing lipid peroxide and radical formation and enhancing GSH and GSSG contents.

  19. 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.

  20. 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).

  1. Davis Pond Freshwater Prediversion Biomonitoring Study: Freshwater Fisheries and Eagles

    USGS Publications Warehouse

    Jenkins, Jill A.; Bourgeois, E. Beth; Jeske, Clint W.

    2008-01-01

    pesticides and other contaminants. Biomarker data on individual fish, generated at the USGS National Wetlands Research Center (Lafayette, La.), included percent white blood cells in whole blood, spleen weight to body weight ratio, liver weight to body weight ratio, condition factor, splenic macrophage aggregates, and liver microsomal 7-ethoxyresorufin-o-deethylase (EROD) activity. Fish age was estimated by comparing total lengths with values from the same species in the Southeast United States as determined from the literature. Contaminant analyses were coordinated by the U.S. Fish and Wildlife Service (USFWS) Analytical Control Facility (Laurel, Md.), where residues of organochlorine (OC) pesticides, total polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), aliphatic hydrocarbons (AHs), and trace elements were determined. The organic contaminant data were generated at the Mississippi State University Chemical Lab (Mississippi State, Miss.), and the inorganic contaminant data were generated by the Texas A&M University Geochemical and Environmental Research Group (College Station, Tex.). Statistical tests were performed to assess relationships among contaminants, fish age, fish species, and collection sites.

  2. Risks of waterborne copper exposure to a cultivated freshwater Neotropical catfish (Rhamdia quelen).

    PubMed

    Mela, M; Guiloski, I C; Doria, H B; Rabitto, I S; da Silva, C A; Maraschi, A C; Prodocimo, V; Freire, C A; Randi, M A F; Ribeiro, C A Oliveira; de Assis, H C Silva

    2013-02-01

    As it is the case in all animal food production systems, it is often necessary to treat farmed fish for diseases and parasites. Quite frequently, fish farmers still rely on the aggressive use of copper to control bacterial infections and infestations by ecto-parasites, and to manage the spread of diseases. The susceptibility of the neotropical fish Rhamdia quelen to copper was here evaluated at different waterborne copper concentrations (2, 7 or 11 μg Cu L(-1)) for 96 h, through a multi biomarkers approach. Liver histopathological findings revealed leukocyte infiltration, hepatocyte vacuolization and areas of necrosis, causing raised levels of lesions upon exposure to 7 and 11 μg Cu L(-1). Decreased occurrence of free melano-macrophages and increased densities of melano-macrophage centers were noted upon exposure to 11 μg Cu L(-1). Gills showed damages on their secondary lamellae already at 2 μg Cu L(-1); hypertrophy and loss of the microridges of pavement cells at 7 and 11 μg L(-1), and increased in chloride cell (CC) apical surface area (4.9-fold) and in CC density (1.5-fold) at 11 μg Cu L(-1). In the liver, catalase (CAT), glutathione peroxidase activities (GPx) and glutathione concentration (GSH) remained unchanged, compared to the control group. However, there was inhibition of 7-ethoxyresorufin-O-deethylase (EROD) at all copper concentrations tested. Glutathione reductase activity (GR) was reduced and levels of lipid peroxidation (LPO) were increased at 11 μg Cu L(-1). Glutathione S-transferase activity (GST) at 7 μg Cu L(-1) and superoxide dismutase activity (SOD) at both 7 and 11 μg Cu L(-1) were reduced. However, copper exposure did not alter brain and muscle acetylcholinesterase (AChE) activity. Osmoregulatory function was also disturbed, in agreement with the above-mentioned changes noted in the gills, as detected by plasma osmolality reduction in the group exposed to 11 μg Cu L(-1), and plasma chloride reduction at 2 μg Cu L(-1). These

  3. 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

  4. 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.

  5. 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

  6. 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).

  7. 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.

  8. 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.

  9. 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

  10. 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

  11. 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

  12. 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.

  13. 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.

  14. 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.

  15. 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

  16. 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

  17. 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.

  18. 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

  19. Biochemical responses in armored catfish (Pterygoplichthys anisitsi) after short-term exposure to diesel oil, pure biodiesel and biodiesel blends.

    PubMed

    Nogueira, Lílian; da Silva, Danilo Grünig Humberto; Oliveira, Thiago Yukio Kikuchi; da Rosa, Joel Maurício Correa; Felício, Andréia Arantes; de Almeida, Eduardo Alves

    2013-09-01

    Biodiesel fuel is gradually replacing petroleum-based diesel oil use. Despite the biodiesel being considered friendlier to the environment, little is known about its effects in aquatic organisms. In this work we evaluated whether biodiesel exposure can affect oxidative stress parameters and biotransformation enzymes in armored catfish (Pterygoplichthys anisitsi, Loricariidae), a South American endemic species. Thus, fish were exposed for 2 and 7d to 0.01mLL(-1) and 0.1mLL(-1) of pure diesel, pure biodiesel (B100) and blends of diesel with 5% (B5) and 20% (B20) biodiesel. Lipid peroxidation (malondialdehyde) levels and the activities of the enzymes glutathione S-transferase, superoxide dismutase, catalase and glutathione peroxidase were measured in liver and gills. Also, DNA damage (8-oxo-7, 8-dihydro-2'-deoxyguanosine) levels in gills and 7-ethoxyresorufin-O-deethylase activity in liver were assessed. Pure diesel, B5 and B20 blends changed most of the enzymes tested and in some cases, B5 and B20 induced a higher enzyme activity than pure diesel. Antioxidant system activation in P. anisitsi was effective to counteract reactive oxygen species effects, since DNA damage and lipid peroxidation levels were maintained at basal levels after all treatments. However, fish gills exposed to B20 and B100 presented increased lipid peroxidation. Despite biodiesel being more biodegradable fuel that emits less greenhouse gases, the increased lipid peroxidation showed that biofuel and its blends also represent hazards to aquatic biota.

  20. BDE-99, but not BDE-47, is a transient aryl hydrocarbon receptor agonist in zebrafish liver cells.

    PubMed

    Yang, Jie; Zhu, Jinyong; Chan, King Ming

    2016-08-15

    Polybrominated diphenyl ethers (PBDEs) are endocrine-disrupting chemicals that affect the environment and the health of humans and wildlife. In this study, the zebrafish liver (ZFL) cell line was used in vitro to investigate two major PBDE contaminants: 2, 2', 4, 4', 5-pentabromodiphenyl ether (BDE-99) and 2, 2', 4, 4'-tetrabromodiphenyl ether (BDE-47). BDE-99 was found to significantly induce cytochrome P450 (CYP1A), uridine diphosphate glucuronosyl transferase 1 family a, b (ugt1ab), 7-ethoxyresorufin-O-deethylase activity and an aryl hydrocarbon receptor (Ahr) dependent xenobiotic response element luciferase reporter system, confirming the Ahr-mediated activation of CYP1A by BDE-99. The time-course effect indicated that the role of BDE-99 in Ahr-mediated signaling is likely to be transient and highly dependent on the ability of BDE-99 to induce CYP1A and ugt1ab, and presumably its metabolism. BDE-99 also exhibited a significant dose-response effect on a developed zebrafish pregnane X receptor luciferase reporter gene system. However, the other abundant contaminant under study, BDE-47, did not exhibit the above effects. Together, these results indicated that the molecular mechanism of PBDEs induced in ZFL cells is a chemically specific process that differs between members of the PBDE family. CYP1A induction derived by BDE-99 warrants further risk assessment as the humans, wildlife and environment are exposed to a complex mixture including dioxin-like compounds and carcinogenic compounds. PMID:27343407

  1. Evaluation of the Ecotoxicity of Sediments from Yangtze River Estuary and Contribution of Priority PAHs to Ah Receptor-Mediated Activities

    PubMed Central

    Liu, Li; Chen, Ling; Shao, Ying; Zhang, Lili; Floehr, Tilman; Xiao, Hongxia; Yan, Yan; Eichbaum, Kathrin; Hollert, Henner; Wu, Lingling

    2014-01-01

    In this study, in vitro bioassays were performed to assess the ecotoxicological potential of sediments from Yangtze River estuary. The cytotoxicity and aryl hydrocarbon receptor (AhR)-mediated toxicity of sediment extracts with rainbow trout (Oncorhynchus mykiss) liver cells were determined by neutral red retention and 7-ethoxyresorufin-O-deethylase assays. The cytotoxicity and AhR-mediated activity of sediments from the Yangtze River estuary ranged from low level to moderate level compared with the ecotoxicity of sediments from other river systems. However, Yangtze River releases approximately 14 times greater water discharge compared with Rhine, a major river in Europe. Thus, the absolute pollution mass transfer of Yangtze River may be detrimental to the environmental quality of estuary and East China Sea. Effect-directed analysis was applied to identify substances causing high dioxin-like activities. To identify unknown substances contributing to dioxin-like potencies of whole extracts, we fractionated crude extracts by open column chromatography. Non-polar paraffinic components (F1), weakly and moderately polar components (F2), and highly polar substances (F3) were separated from each crude extract of sediments. F2 showed the highest dioxin-like activities. Based on the results of mass balance calculation of chemical toxic equivalent concentrations (TEQs), our conclusion is that priority polycyclic aromatic hydrocarbons indicated a low portion of bio-TEQs ranging from 1% to 10% of crude extracts. Further studies should be conducted to identify unknown pollutants. PMID:25111307

  2. Molecular responses as indicators of marine pollution: DNA damage and enzyme induction in Limanda limanda and Asterias rubens

    SciTech Connect

    Everaarts, J.M.; Sleiderink, H.M.; Besten, P.J. den

    1994-12-01

    During a survey from 26 August through 13 September 1991, specimens of the flatfish, Limanda limanda (dab), and the asteroid echinoderm, Asterias rubens (seastar), were collected at sampling locations along transacts radiating into the North Sea from the coastal zone of The Netherlands. In homogenates of liver tissue from male dab and the digestive gland (pyloric caeca) of female seastar, DNA damage (strand breaks) and induction of the cytochrome P450-dependent monooxygenase system (MO) were determined. Areas could be described with significantly increased percentages of strand breaks (lower integrity) both in dab and seastar. However, enhanced DNA strand breaks did not correspond with contamination gradients, expressed as concentrations of polychlorinated biphenyls (PCBs) or polyaromatic hydrocarbons. MO enzyme induction in the hepatic 13,000g fraction of male dab, measured as 7-ethoxyresorufin-O-deethylase activity, was significantly enhanced in response to low ambient temperatures. Some evidence was found for the facilitation of benzo[a]pyrene hydroxylase activity expressing the enzyme induction in the microsomal fraction of pyloric caeca of seastars, at increasing PCB concentrations. DNA integrity and enzyme induction elucidate the physiologic status and might be indicative for ambient impairment within restricted areas, and not necessarily related to the presence of anthropogenic or xeno-biotic substances. 27 refs., 5 figs., 1 tab.

  3. Passive sampler for combined chemical and toxicological long-term monitoring of groundwater: the ceramic toximeter.

    PubMed

    Bopp, Stephanie K; McLachlan, Michael S; Schirmer, Kristin

    2007-10-01

    We present the development of a passive sampling device that combines chemical with biological assessment of water following time-integrating, long-term sampling. The new device, which was designated the Ceramic Toximeter, brings together the simplicity of the Ceramic Dosimeter as a ceramic membrane-based, solid-sorbent sampler and the uniqueness of a recently developed solid-phase, solvent-free bioassay. In this bioassay, Biosilon, i.e., polystyrene polymer beads, is used to present sorbed contaminants to vertebrate cells that adhere to the contaminant-loaded Biosilon and respond. Focusing on Biosilon as sorbent, its ability to accumulate 16 polycyclic aromatic hydrocarbons (PAHs) was explored. When tested up to 42 days in the laboratory or 1 year in groundwater at a contaminated gasworks site, Biosilon-filled Ceramic Toximeters yielded back-calculated time-weighted average aqueous PAH concentrations that agreed well with concentrations obtained by frequent snapshot sampling. The chosen bioassay response, the induction of 7-ethoxyresorufin-O-deethylase, was as predicted in the laboratory setting but could only partly be explained by the analyzed PAHs in the field. Based on this first assessment, the Ceramic Toximeter emerges as a resource efficient water monitoring device with a variety of potential future applications. PMID:17969708

  4. Chemical residues and biochemical responses in wild and cultured European sea bass (Dicentrarchus labrax L.)

    SciTech Connect

    Fernandes, Denise; Porte, Cinta . E-mail: cpvqam@cid.csic.es; Bebianno, Maria Joao

    2007-02-15

    Cultured and wild sea bass (Dicentrarchus labrax) from the Arade Estuary were sampled in summer and winter and the degree of exposure to metals and polycyclic aromatic hydrocarbons (PAHs) assessed, together with some biochemical responses against those and other pollutants. The highest levels of copper (up to 997 {mu}g g{sup -1} dry weight) and cadmium (up to 4.22 {mu}g g{sup -1} dry weight) were detected in the liver and kidney of cultured specimens, whereas the highest exposure to PAHs was observed in wild fish. Significant alterations in some biochemical markers were detected and associated to pollutant exposure. Thus, metallothionein concentrations were higher in the tissues of cultured fish and positively correlated with metal residues. The activity 7-ethoxyresorufin O-deethylase ranged from 28 pmol/min/mg protein in cultured fish to 83 pmol/min/mg protein in wild fish collected near a marina area. Cultured fish and wild fish from the marina area had depressed acetylcholinesterase in muscle tissue and a parasitic infection in the gonads. The obtained results support the usefulness of the combined use of chemical and biochemical markers to assess the impact of anthropogenic pollutants in both wild and cultured fish.

  5. Nitrite-induced enhancement of toxicity of phenanthrene in fish and its implications for coastal waters

    NASA Astrophysics Data System (ADS)

    Shailaja, M. S.; Rodrigues, A.

    2003-04-01

    Coastal areas are prone to varying degrees of anthropogenic chemical contamination. In many coastal environments experiencing reducing conditions in the water column, nitrite is produced as a result of denitrification. With a view to determining the effect of a natural stress such as the presence of nitrite in water on the xenobiotic metabolism in fish, the euryhaline cichlid Oreochromis mossambicus was exposed for up to 9 days to environmentally relevant concentrations of water-borne nitrite and phenanthrene, a polycyclic aromatic hydrocarbon. Analyses of different biomarkers in the treated fish indicated significant increase in the metabolism of phenanthrene as a result of exposure to nitrite. For example, the activity of the biotransformation enzyme measured as 7-ethoxyresorufin- O-deethylase activity was, in the presence of 1 μM nitrite, nearly twice that produced by phenanthrene alone. Similarly, biliary fixed fluorescence values reflecting phenanthrene and its metabolites were rendered 1.7 times higher when exposed simultaneously to nitrite. Contact with nitrite and phenanthrene together also led to severe hepatic damage with possible cell death as inferred from the large enhancement in sorbitol dehydrogenase activity in the serum and reduced liver somatic index.

  6. Effect of β-naphthoflavone on hepatic cytochrome P4501A activity in the scribbled rabbitfish (Siganus spinus) from tropical Indo-Pacific coral reefs.

    PubMed

    Emborski, Carmen; Reyes, Andres; Biggs, Jason S

    2012-11-01

    Several classes of carcinogenic environmental organic pollutants, including polycyclic aromatic hydrocarbons, polychlorinated biphenyls, and dioxins, negatively affect aquatic ecosystems worldwide. Pollutant detection is often difficult and expensive, especially when dealing with complex mixtures and matrices. Biological markers are informative tools to identify living sources that may harbor toxic compounds and areas unsuitable for recreation. Currently, no species have established biomarkers for organopollutant monitoring in Indo-Pacific coral reefs. This study evaluated the time- and dose-dependent induction of the cytochrome P4501A (CYP1A) system in the scribbled rabbitfish, Siganus spinus (Siganidae), as a biomarker for organic pollutant exposures in these environments. Results indicate that S. spinus hepatic CYP1A enzymatic activity and protein level respond dose-, and time-dependently following a single intraperitoneal injection of the classic aryl hydrocarbon receptor agonist, β-naphthoflavone. S. spinus hepatic CYP1A protein and enzymatic activity rose as function of dose during the first two days and slowly returned to levels close to normal after 16 days, as measured using the 7-ethoxyresorufin-O-deethylase and the non-competitive enzyme-linked immunosorbent assays, respectively. These findings support use of the inducible CYP1A system of S. spinus as a biomarker for reef fish exposure to coastal marine pollution. Baseline CYP1A expression levels among Guam's wild S. spinus populations were also measured and compared.

  7. BDE-99, but not BDE-47, is a transient aryl hydrocarbon receptor agonist in zebrafish liver cells.

    PubMed

    Yang, Jie; Zhu, Jinyong; Chan, King Ming

    2016-08-15

    Polybrominated diphenyl ethers (PBDEs) are endocrine-disrupting chemicals that affect the environment and the health of humans and wildlife. In this study, the zebrafish liver (ZFL) cell line was used in vitro to investigate two major PBDE contaminants: 2, 2', 4, 4', 5-pentabromodiphenyl ether (BDE-99) and 2, 2', 4, 4'-tetrabromodiphenyl ether (BDE-47). BDE-99 was found to significantly induce cytochrome P450 (CYP1A), uridine diphosphate glucuronosyl transferase 1 family a, b (ugt1ab), 7-ethoxyresorufin-O-deethylase activity and an aryl hydrocarbon receptor (Ahr) dependent xenobiotic response element luciferase reporter system, confirming the Ahr-mediated activation of CYP1A by BDE-99. The time-course effect indicated that the role of BDE-99 in Ahr-mediated signaling is likely to be transient and highly dependent on the ability of BDE-99 to induce CYP1A and ugt1ab, and presumably its metabolism. BDE-99 also exhibited a significant dose-response effect on a developed zebrafish pregnane X receptor luciferase reporter gene system. However, the other abundant contaminant under study, BDE-47, did not exhibit the above effects. Together, these results indicated that the molecular mechanism of PBDEs induced in ZFL cells is a chemically specific process that differs between members of the PBDE family. CYP1A induction derived by BDE-99 warrants further risk assessment as the humans, wildlife and environment are exposed to a complex mixture including dioxin-like compounds and carcinogenic compounds.

  8. Effect of β-naphthoflavone on hepatic cytochrome P4501A activity in the scribbled rabbitfish (Siganus spinus) from tropical Indo-Pacific coral reefs.

    PubMed

    Emborski, Carmen; Reyes, Andres; Biggs, Jason S

    2012-11-01

    Several classes of carcinogenic environmental organic pollutants, including polycyclic aromatic hydrocarbons, polychlorinated biphenyls, and dioxins, negatively affect aquatic ecosystems worldwide. Pollutant detection is often difficult and expensive, especially when dealing with complex mixtures and matrices. Biological markers are informative tools to identify living sources that may harbor toxic compounds and areas unsuitable for recreation. Currently, no species have established biomarkers for organopollutant monitoring in Indo-Pacific coral reefs. This study evaluated the time- and dose-dependent induction of the cytochrome P4501A (CYP1A) system in the scribbled rabbitfish, Siganus spinus (Siganidae), as a biomarker for organic pollutant exposures in these environments. Results indicate that S. spinus hepatic CYP1A enzymatic activity and protein level respond dose-, and time-dependently following a single intraperitoneal injection of the classic aryl hydrocarbon receptor agonist, β-naphthoflavone. S. spinus hepatic CYP1A protein and enzymatic activity rose as function of dose during the first two days and slowly returned to levels close to normal after 16 days, as measured using the 7-ethoxyresorufin-O-deethylase and the non-competitive enzyme-linked immunosorbent assays, respectively. These findings support use of the inducible CYP1A system of S. spinus as a biomarker for reef fish exposure to coastal marine pollution. Baseline CYP1A expression levels among Guam's wild S. spinus populations were also measured and compared. PMID:22760666

  9. Evaluation of the ecotoxicity of sediments from Yangtze river estuary and contribution of priority PAHs to ah receptor--mediated activities.

    PubMed

    Liu, Li; Chen, Ling; Shao, Ying; Zhang, Lili; Floehr, Tilman; Xiao, Hongxia; Yan, Yan; Eichbaum, Kathrin; Hollert, Henner; Wu, Lingling

    2014-01-01

    In this study, in vitro bioassays were performed to assess the ecotoxicological potential of sediments from Yangtze River estuary. The cytotoxicity and aryl hydrocarbon receptor (AhR)-mediated toxicity of sediment extracts with rainbow trout (Oncorhynchus mykiss) liver cells were determined by neutral red retention and 7-ethoxyresorufin-O-deethylase assays. The cytotoxicity and AhR-mediated activity of sediments from the Yangtze River estuary ranged from low level to moderate level compared with the ecotoxicity of sediments from other river systems. However, Yangtze River releases approximately 14 times greater water discharge compared with Rhine, a major river in Europe. Thus, the absolute pollution mass transfer of Yangtze River may be detrimental to the environmental quality of estuary and East China Sea. Effect-directed analysis was applied to identify substances causing high dioxin-like activities. To identify unknown substances contributing to dioxin-like potencies of whole extracts, we fractionated crude extracts by open column chromatography. Non-polar paraffinic components (F1), weakly and moderately polar components (F2), and highly polar substances (F3) were separated from each crude extract of sediments. F2 showed the highest dioxin-like activities. Based on the results of mass balance calculation of chemical toxic equivalent concentrations (TEQs), our conclusion is that priority polycyclic aromatic hydrocarbons indicated a low portion of bio-TEQs ranging from 1% to 10% of crude extracts. Further studies should be conducted to identify unknown pollutants.

  10. Two cytochrome P-450 isoforms catalysing O-de-ethylation of ethoxycoumarin and ethoxyresorufin in higher plants.

    PubMed Central

    Werck-Reichhart, D; Gabriac, B; Teutsch, H; Durst, F

    1990-01-01

    The O-dealkylating activities of 7-ethoxycoumarin O-de-ethylase (ECOD) and 7-ethoxyresorufin O-de-ethylase (EROD) have been fluorimetrically detected in microsomes prepared from manganese-induced Jerusalem artichoke tubers. Cytochrome P-450 dependence of the reactions was demonstrated by light-reversed CO inhibition, NADPH-dependence, NADH-NADPH synergism and by use of specific inhibitors: antibodies to NADPH-cytochrome P-450 reductase, mechanism-based inactivators and tetcyclasis. Apparent Km values of 161 microM for 7-ethoxycoumarin and 0.4 microM for 7-ethoxyresorufin were determined. O-De-ethylase activity was also detected in microsomes prepared from several other plant species, including wheat, maize, tulip, avocado and Vicia. ECOD and EROD were low or undetectable in uninduced plant tissues, and both activities were stimulated by wounding or by chemical inducers. Two distinct cytochrome P-450 isoforms are involved in ECOD and EROD activities since (1) they showed different distributions among plant species; (2) they showed contrasting inhibition and induction patterns; and (3) ECOD but not EROD activity was supported by cumene hydroperoxide. PMID:2241905

  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. Identification of a novel series of N-phenyl-5-[(2-phenylbenzimidazol-1-yl)methyl]-1,3,4-oxadiazol-2-amines as potent antioxidants and radical scavengers.

    PubMed

    Ayhan-Kilcigil, Gulgun; Kuş, Canan; Çoban, Tülay; Özdamar, Elcin D; Can-Eke, Benay

    2014-04-01

    In this study, some novel 5-[[2-(phenyl/p-chlorophenyl)-benzimidazol-1-yl]-methyl]-N-substituted phenyl-1,3,4-oxadiazol-2-amine derivatives (28-45) with an oxadiazole ring were synthesized. The antioxidant properties and radical scavenging activities of the compounds were investigated employing various in vitro systems: hepatic microsomal NADPH-dependent inhibition of lipid peroxidation levels, scavenging of DPPH free radicals, and inhibition of microsomal ethoxyresorufin O-deethylase activity (EROD). Compounds 34 and 41 were found to be good scavengers of DPPH radicals (76% and 84%) when compared to BHT (90%). Almost all of the compounds examined were found to possess a good inhibitor effect on the microsomal EROD activity. Moreover, 32 and 41 were more active analogs (97% and 98%) on the microsomal EROD activity than caffeine (85%).

  13. Assessment of contamination of the Svitava and Svratka rivers in the Czech Republic using selected biochemical markers.

    PubMed

    Blahová, Jana; Havelková, Marcela; Kruzíková, Kamila; Hilscherová, Klára; Halouzka, Roman; Modrá, Helena; Grabic, Roman; Halírová, Jarmila; Jurcíková, Jana; Ocelka, Tomás; Harustiaková, Danka; Svobodová, Zdenka

    2010-03-01

    The aim of the present study is to assess aquatic ecosystem contamination using selected biochemical markers: cytochrome P450, ethoxyresorufin-O-deethylase (EROD), glutathione S-transferase (GST), tripeptide glutathione, vitellogenin, and 11-ketotestosterone in chub (Leuciscus cephalus L.). Seven locations on the Svitava and Svratka rivers (in the Brno conurbation, Czech Republic) were assessed. The results were compared with the levels of the most important inductors of these biomarkers: organic pollutants hexachlorocyclohexane (HCH), hexachlorobenzene (HCB), DDT and its metabolites, polychlorinated biphenyls, and polycyclic aromatic hydrocarbons in bottom sediment, fish muscle, and semipermeable membrane devices (SPMDs) and metals in sediment. The highest levels of pollutants were observed at sites situated downstream from Brno, especially at Modrice and Rajhradice. Significant positive correlations (p < 0.05) were found between EROD activity and HCH concentration in SPMDs, and also between GST and EROD activity with HCB concentration in muscle, after adjusting for age.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. [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.

  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. Reduction of dioxin-like toxicity in effluents by additional wastewater treatment and related effects in fish.

    PubMed

    Maier, Diana; Benisek, Martin; Blaha, Ludek; Dondero, Francesco; Giesy, John P; Köhler, Heinz-R; Richter, Doreen; Scheurer, Marco; Triebskorn, Rita

    2016-10-01

    Efficiency of advanced wastewater treatment technologies to reduce micropollutants which mediate dioxin-like toxicity was investigated. Technologies compared included ozonation, powdered activated carbon and granular activated carbon. In addition to chemical analyses in samples of effluents, surface waters, sediments, and fish, (1) dioxin-like potentials were measured in paired samples of effluents, surface waters, and sediments by use of an in vitro biotest (reporter gene assay) and (2) dioxin-like effects were investigated in exposed fish by use of in vivo activity of the mixed-function, monooxygenase enzyme, ethoxyresorufin O-deethylase (EROD) in liver. All advanced technologies studied, based on degradation or adsorption, significantly reduced dioxin-like potentials in samples and resulted in lesser EROD activity in livers of fish. Results of in vitro and in vivo biological responses were not clearly related to quantification of targeted analytes by use of instrumental analyses. PMID:27262214

  1. The effects of oil exposure on peripheral blood leukocytes and splenic melano-macrophage centers of Gulf of Mexico fishes.

    PubMed

    Ali, Ahmad Omar; Hohn, Claudia; Allen, Peter J; Ford, Lorelei; Dail, Mary Beth; Pruett, Stephen; Petrie-Hanson, Lora

    2014-02-15

    In August and November 2010 we collected and examined peripheral blood and tissues from three species of Gulf of Mexico fish. Findings were compared to non-exposed control fish. The leukocyte counts of exposed alligator gar were not significantly different from controls, while exposed Gulf killifish and sea trout had significantly decreased lymphocyte counts. Liver ethoxyresorufin-O-deethylase (EROD) values from sea trout were significantly greater than control sea trout EROD values, suggesting poly aromatic hydrocarbon exposure. Splenic melano-macrophage centers (MMCs) from exposed sea trout and Gulf killifish showed a significant increase in number compared to non-exposed fish. Sea trout splenic MMCs were also significantly greater in size. These findings suggest that Gulf fish sampled were exposed to crude oil from the Macondo well and were in a lymphopenic or immuno-compromised state. PMID:24405733

  2. The effects of oil exposure on peripheral blood leukocytes and splenic melano-macrophage centers of Gulf of Mexico fishes.

    PubMed

    Ali, Ahmad Omar; Hohn, Claudia; Allen, Peter J; Ford, Lorelei; Dail, Mary Beth; Pruett, Stephen; Petrie-Hanson, Lora

    2014-02-15

    In August and November 2010 we collected and examined peripheral blood and tissues from three species of Gulf of Mexico fish. Findings were compared to non-exposed control fish. The leukocyte counts of exposed alligator gar were not significantly different from controls, while exposed Gulf killifish and sea trout had significantly decreased lymphocyte counts. Liver ethoxyresorufin-O-deethylase (EROD) values from sea trout were significantly greater than control sea trout EROD values, suggesting poly aromatic hydrocarbon exposure. Splenic melano-macrophage centers (MMCs) from exposed sea trout and Gulf killifish showed a significant increase in number compared to non-exposed fish. Sea trout splenic MMCs were also significantly greater in size. These findings suggest that Gulf fish sampled were exposed to crude oil from the Macondo well and were in a lymphopenic or immuno-compromised state.

  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)

    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.

  4. 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.

  5. Bioconcentration, metabolism and effects of diphenhydramine on behavioral and biochemical markers in crucian carp (Carassius auratus).

    PubMed

    Xie, Zhengxin; Lu, Guanghua; Hou, Kangkang; Qin, Donghong; Yan, Zhenhua; Chen, Wei

    2016-02-15

    Diphenhydramine (DPH), an antihistamine used to alleviate human allergies, is widespread in aquatic environments. However, little is known about the biochemical and behavioral effects of DPH on non-target aquatic animals. In the present study, the tissue distribution, bioconcentration, metabolism, biochemical and behavioral effects were investigated in crucian carp (Carassius auratus) exposed to various concentrations of DPH (0.84, 4.23, 21.7 and 112 μg L(-1)) for 7d. DPH can accumulate in crucian carp, and high concentrations have been observed in the liver and brain with maximum bioconcentration factors of 148 and 81.6, respectively. A portion of the absorbed DPH was metabolized by the crucian carp to N-demethyl DPH and N,N-didemethyl DPH via N-demethylation. Direct fluorimetric assay was employed to assess metabolic activity, while oxidative stress and neurotransmission biomarkers were determined by Diagnostic Reagent Kits. DPH was found to increase hepatic 7-ethoxyresorufin O-deethylase activity in crucian carp with maximal induction of 119%. Concerning the oxidative stress status, DPH significantly inhibited superoxide dismutase (SOD, 37-58%) and glutathione S-transferase (GST, 43-65%) activities and led to a significant increase in malondialdehyde (MDA, 67-140%) levels and catalase (CAT, 38-143%) and glutathione peroxidase (GPx, 39-189%) activities in fish liver. Brain acetylcholinesterase activity was also induced in DPH-exposed crucian carp with maximal induction of 174%. In addition, shoaling was significantly enhanced, while swimming activity and feeding rates were markedly suppressed at DPH concentrations equal to or higher than 21.7 μg L(-1). Furthermore, significant correlations were found between oxidative stress biomarkers (SOD, CAT, GPx, GST and MDA) and behavioral parameters. Collectively, our results confirmed that DPH can accumulate and be metabolized in fish and exert a negative effect at different levels of biological organization. PMID

  6. Changes of biomarkers with oral exposure to benzo(a)pyrene, phenanthrene and pyrene in rats

    PubMed Central

    Kang, Hwan Goo; Cho, Myung Haing; Cho, Joon Hyoung

    2007-01-01

    Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous environmental contaminants present in air and food. Among PAHs, benzo(a)pyrene(BaP), phenanthrene (PH) and pyrene (PY) are considered to be important for their toxicity or abundance. To investigate the changes of biomarkers after PAH exposure, rats were treated with BaP (150 µg/kg) alone or with PH (4,300 µg/kg) and PY (2,700 µg/kg) (BPP group) by oral gavage once per day for 30 days. 7-ethoxyresorufin-O-deethylase activity in liver microsomal fraction was increased in only BaP groups. The highest concentration (34.5 ng/g) of BaP, was found in muscle of rats treated with BaP alone at 20 days of treatment; it was 23.6 ng/g in BPP treated rats at 30 days of treatment. The highest PH concentration was 47.1 ng/g in muscle and 118.8 ng/g in fat, and for PY it was 29.7 ng/g in muscle and 219.9 ng/g in fat, in BPP groups. In urine, 114-161 ng/ml 3-OH-PH was found, while PH was 41-69 ng/ml during treatment. 201-263 ng/ml 1-OH-PY was found, while PH was 9-17 ng/ml in urine. The level of PY, PH and their metabolites in urine was rapidly decreased after withdrawal of treatment. This study suggest that 1-OH-PY in urine is a sensitive biomarker for PAHs; it was the most highly detected marker among the three PAHs and their metabolites evaluated during the exposure period and for 14 days after withdrawal. PMID:17993750

  7. Newspapers and newspaper ink contain agonists for the ah receptor.

    PubMed

    Bohonowych, Jessica E S; Zhao, Bin; Timme-Laragy, Alicia; Jung, Dawoon; Di Giulio, Richard T; Denison, Michael S

    2008-04-01

    Ligand-dependent activation of the aryl hydrocarbon receptor (AhR) pathway leads to a diverse array of biological and toxicological effects. The best-studied ligands for the AhR include polycyclic and halogenated aromatic hydrocarbons, the most potent of which is 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). However, as new AhR ligands are identified and characterized, their structural and physiochemical diversity continues to expand. Our identification of AhR agonists in crude extracts from diverse materials raises questions as to the magnitude and extent of human exposure to AhR ligands through normal daily activities. We have found that solvent extracts of newspapers from countries around the world stimulate the AhR signaling pathway. AhR agonist activity was observed for dimethyl sulfoxide (DMSO), ethanol, and water extracts of printed newspaper, unprinted virgin paper, and black printing ink, where activation of luciferase reporter gene expression was transient, suggesting that the AhR active chemical(s) was metabolically labile. DMSO and ethanol extracts also stimulated AhR transformation and DNA binding, and also competed with [(3)H]TCDD for binding to the AhR. In addition, DMSO extracts of printed newspaper induced cytochrome P450 1A associated 7-ethoxyresorufin-O-deethylase activity in zebrafish embryos in vivo. Although the responsible bioactive chemical(s) remain to be identified, our results demonstrate that newspapers and printing ink contain relatively potent metabolically labile agonists of the AhR. Given the large amount of recycling and reprocessing of newspapers throughout the world, release of these easily extractable AhR agonists into the environment should be examined and their potential effects on aquatic organisms assessed. PMID:18203687

  8. Characterization of the structural determinants required for potent mechanism-based inhibition of human cytochrome P450 1A1 by cannabidiol.

    PubMed

    Yamaori, Satoshi; Okushima, Yoshimi; Yamamoto, Ikuo; Watanabe, Kazuhito

    2014-05-25

    We previously demonstrated that cannabidiol (CBD) was a potent mechanism-based inhibitor of human cytochrome P450 1A1 (CYP1A1). However, the moiety of CBD that contributes to the potent mechanism-based inhibition of human CYP1A1 remains unknown. Thus, the effects of compounds structurally related to CBD on CYP1A1 activity were examined with recombinant human CYP1A1 in order to characterize the structural requirements for potent inactivation by CBD. When preincubated in the presence of NADPH for 20min, olivetol, which corresponds to the pentylresorcinol moiety of CBD, enhanced the inhibition of the 7-ethoxyresorufin O-deethylase activity of CYP1A1. In contrast, d-limonene, which corresponds to the terpene moiety of CBD, failed to inhibit CYP1A1 activity in a metabolism-dependent manner. Pentylbenzene, which lacks two free phenolic hydroxyl groups, also did not enhance CYP1A1 inhibition. On the other hand, preincubation of the CBD-2'-monomethyl ether (CBDM) and CBD-2',6'-dimethyl ether (CBDD) enhanced the inhibition of CYP1A1 activity. Inhibition by cannabidivarin (CBDV), which possessed a propyl side chain, was strongly potentiated by its preincubation. Orcinol, which has a methyl group, augmented CYP1A1 inhibition, whereas its derivative without an alkyl side chain, resorcinol, did not exhibit any metabolism-dependent inhibition. The preincubation of CBD-hydroxyquinone did not markedly enhance CYP1A1 inhibition. We further confirmed that olivetol, CBDM, CBDD, CBDV, and orcinol, as well as CBD (kinact=0.215min(-1)), inactivated CYP1A1 activity; their kinact values were 0.154, 0.0638, 0.0643, 0.226, and 0.0353min(-1), respectively. These results suggest that the methylresorcinol structure in CBD may have structurally important roles in the inactivation of CYP1A1.

  9. Induction of cytochrome P450 1A1 and monooxygenase activity in Tilapia by sediment extract

    SciTech Connect

    Ueng, Y.F.; Ueng, T.H.; Liu, T.Y.

    1995-01-01

    Cytochrome P450 (P450)-dependent monooxygenases of fishes are inducible by a variety of environmental pollutants including polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs). Induction of fish monoxygenases may serve as a biological monitor for PAH- and PCB-types of environmental chemicals. Many studies have demonstrated environmental induction of fish monooxygenases using various experimental approaches. However, relatively few studies have been conducted using fish treated with contaminated river sediment extracts. Damsui River is the largest river in the north of Taiwan. The lower section of the river in the Taipei Metropolitan area is heavily polluted by industrial and municipal wastes. Tilapia (Oreochromis mossambicus) is one of the few species of fish that occur in the polluted river. Previous field studies showed that the levels of P450 1A1, benzo(a)pyrene hydroxylase and 7-ethoxyresorufin O-deethylase activities in tilapia collected at Fu-Ho Bridge, a polluted section of Damsui River, were higher than respective levels in fish collected from an unpolluted section. These results suggested that tilapia caught at the polluted site were exposed to substances similar in action to PAHs and PCBs, because these chemical pollutants are potent inducers of P450 1A1. PAHs and PCBs are persistent compounds that can accumulate in sediment. Tilapia are occasionally associated with the bottom and could ingest chemically contaminated sediment. In the present study, we determined the induction properties of monooxygenases using tilapia treated with extract of sediment collected from a polluted section of Damsui River. The present study demonstrates that Damsui River sediment extract has the ability to induce hepatic P450 1A1 and dependent monooxygenase activities in tilapia. 17 refs., 2 figs., 2 tabs.

  10. Effect of butylated hydroxytoluene, curcumin, propyl gallate and thiabendazole on cytochrome P450 forms in cultured human hepatocytes.

    PubMed

    Price, R J; Scott, M P; Giddings, A M; Walters, D G; Stierum, R H; Meredith, C; Lake, B G

    2008-06-01

    1. The objective of this study was to investigate the effects of four food chemicals, namely butylated hydroxytoluene (BHT), curcumin (CC), propyl gallate (PG) and thiabendazole (TB), on cytochrome P450 (CYP) forms in cultured human hepatocytes. 2. Treatment of human hepatocytes for 72 h with 2-200 microM TB produced concentration-dependent increases in CYP1A2, CYP2B6 and CYP3A4 mRNA levels, whereas treatment with BHT increased CYP2B6 and CYP3A4 mRNA levels. CYP1A2, CYP2B6 and CYP3A4 mRNA levels were induced around 48-, 21- and 9-fold, respectively, by 200 microM TB, with CYP2B6 and CYP 3A4 mRNA levels being induced around 12- and 7-fold, respectively, by 200 microM BHT. 3. In contrast, the treatment of human hepatocytes for 72 h with PG and CC had little or no effect on CYP mRNA levels. 4. The treatment of human hepatocytes with TB also induced CYP1A-dependent 7-ethoxyresorufin O-deethylase activity, whereas BHT induced CYP3A-dependent testosterone 6beta-hydroxylase activity. 5. In summary, the results demonstrate that TB is a mixed inducer of CYP forms in human hepatocytes inducing CYP1A, CYP2B and CYP3A forms, whereas BHT is an inducer of CYP2B and CYP3A forms.

  11. Stable nitrogen isotopes of nestling tree swallows indicate exposure to different types of oil sands reclamation.

    PubMed

    Farwell, A J; Harms, N J; Smits, J E G; Dixon, D G

    2014-01-01

    Tree swallows (Tachycineta bicolor) inhabiting reclaimed wetlands on the oil sands in northern Alberta are potentially exposed to elevated levels of oil sands constituents such as polycyclic aromatic compounds (PAC) through diet. While increased detoxification enzyme activity as measured using 7-ethoxyresorufin O-deethylase in nestlings is a generally accepted indicator of exposure to oil sands constituents, there is no apparent method to detect dietary exposure specific to oil sands processed material (OSPM). In this study, stable C and N isotopes were analyzed from muscle and feathers of nestling tree swallows (15 d old) to distinguish dietary exposure of birds near reference and OSPM wetlands. High δ¹⁵N and low δ¹³C values in the nestling tissues differentiated those from the OSPM wetlands and reference sites. Lower δ¹⁵N values of nestlings compared to the δ¹⁵N values of larval chironomids from an earlier study suggested that the majority of the diet of the nestlings was derived from non-OSPM sources, despite residence near and on the OSPM wetlands. Our finding of limited utilization of OSPM resources by tree swallows indicates either low abundance or diversity of dietary items emerging from OSPM wetlands, or sensory avoidance of prey from those wetlands. Minimal consumption of OSPM-derived dietary sources may be attributed to published findings of limited adverse effects on tree swallow reproduction, or growth and development for these same nestlings. This study demonstrated that stable isotope analysis, particularly for N isotopes, may serve as a useful tool to trace dietary exposure to OSPM constituents as part of avian ecotoxicology assessments of reclaimed wetlands on the oil sands. PMID:24627996

  12. Stable nitrogen isotopes of nestling tree swallows indicate exposure to different types of oil sands reclamation.

    PubMed

    Farwell, A J; Harms, N J; Smits, J E G; Dixon, D G

    2014-01-01

    Tree swallows (Tachycineta bicolor) inhabiting reclaimed wetlands on the oil sands in northern Alberta are potentially exposed to elevated levels of oil sands constituents such as polycyclic aromatic compounds (PAC) through diet. While increased detoxification enzyme activity as measured using 7-ethoxyresorufin O-deethylase in nestlings is a generally accepted indicator of exposure to oil sands constituents, there is no apparent method to detect dietary exposure specific to oil sands processed material (OSPM). In this study, stable C and N isotopes were analyzed from muscle and feathers of nestling tree swallows (15 d old) to distinguish dietary exposure of birds near reference and OSPM wetlands. High δ¹⁵N and low δ¹³C values in the nestling tissues differentiated those from the OSPM wetlands and reference sites. Lower δ¹⁵N values of nestlings compared to the δ¹⁵N values of larval chironomids from an earlier study suggested that the majority of the diet of the nestlings was derived from non-OSPM sources, despite residence near and on the OSPM wetlands. Our finding of limited utilization of OSPM resources by tree swallows indicates either low abundance or diversity of dietary items emerging from OSPM wetlands, or sensory avoidance of prey from those wetlands. Minimal consumption of OSPM-derived dietary sources may be attributed to published findings of limited adverse effects on tree swallow reproduction, or growth and development for these same nestlings. This study demonstrated that stable isotope analysis, particularly for N isotopes, may serve as a useful tool to trace dietary exposure to OSPM constituents as part of avian ecotoxicology assessments of reclaimed wetlands on the oil sands.

  13. 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.

  14. Hepatic P450 enzyme activity, tissue morphology and histology of mink (Mustela vison) exposed to polychlorinated dibenzofurans.

    PubMed

    Moore, Jeremy N; Newsted, John L; Hecker, Markus; Zwiernik, Matthew J; Fitzgerald, Scott D; Kay, Denise P; Zhang, Xiaowei; Higley, Eric B; Aylward, Lesa L; Beckett, Kerrie J; Budinsky, Robert A; Bursian, Steven J; Giesy, John P

    2009-08-01

    Dose- and time-dependent effects of environmentally relevant concentrations of 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents (TEQ) of 2,3,7,8-tetrachlorodibenzofuran (TCDF), 2,3,4,7,8-pentachlorodibenzofuran (PeCDF), or a mixture of these two congeners on hepatic P450 enzyme activity and tissue morphology, including jaw histology, of adult ranch mink were determined under controlled conditions. Adult female ranch mink were fed either TCDF (0.98, 3.8, or 20 ng TEQ(TCDF)/kg bw/day) or PeCDF (0.62, 2.2, or 9.5 ng TEQ(PeCDF)/kg bw/day), or a mixture of TCDF and PeCDF (4.1 ng TEQ(TCDF)/kg bw/day and 2.8 ng TEQ(PeCDF)/kg bw/day, respectively) for 180 days. Doses used in this study were approximately eight times greater than those reported in a parallel field study. Activities of the cytochrome P450 1A enzymes, ethoxyresorufin O-deethylase (EROD) and methoxyresorufin O-deethylase (MROD) were significantly greater in livers of mink exposed to TCDF, PeCDF, and a mixture of the two congeners; however, there were no significant histological or morphological effects observed. It was determined that EROD and MROD activity can be used as sensitive biomarkers of exposure to PeCDF and TCDF in adult female mink; however, under the conditions of this study, the response of EROD/MROD induction occurred at doses that were less than those required to cause histological or morphological changes. PMID:19458992

  15. 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.

  16. Identification of cytochrome P4501A inducers in complex mixtures of polycyclic aromatic hydrocarbons

    SciTech Connect

    Villeneuve, D.L.; DeVita, W.M.; Crunkilton, R.L.

    1998-12-31

    An in vitro ethoxyresorufin O-deethylase (EROD) assay was used to study the ability of individual polycyclic aromatic hydrocarbons (PAHs) and mixtures of PAHs to induce Ah receptor (AhR) mediated cytochrome P4501A activity in PLHC-1 fish hepatoma cells. The purpose was to identify the most potent inducers from a set of thirteen separate PAHs and describe interactions occurring in complex mixtures of these PAHs. Where possible, potency was expressed in terms of 2,3,7,8 tetrachlorodibenzo-p-dioxin (TCDD) equivalents (TCDD-EQ) by normalizing the PAH results to a TCDD standard curve. The most potent inducers were benzo(k)fluoranthene > benzo(a)pyrene {approx} benzo(b)fluoranthene > chrysene {approx} benzo(a)anthracene. At equal concentrations, these PAHs yielded potencies of 1670, 940, 655, 255, and 185 pg TCDD-EQ/g, respectively. Analysis of various mixtures of the thirteen PAHs suggested that complex interactions may be occurring.

  17. Antioxidant responses in clam Venerupis philippinarum exposed to environmental pollutant hexabromocyclododecane.

    PubMed

    Zhang, Hui; Pan, Luqing; Tao, Yanxia

    2014-01-01

    The objective of this study was to assess the potential toxic effects of hexabromocyclododecane (HBCD) on tissues of clam Venerupis philippinarum using parameters of antioxidant defenses and oxidative stress. Antioxidant biomarkers including ethoxyresorufin-O-deethylase (EROD), glutathione S-transferase (GST), superoxide dismutase (SOD), and glutathione (GSH), as well as DNA damage and lipid peroxidation (LPO) in gills and digestive glands of V. philippinarum, were analyzed after a 1-, 3-, 6-, 10-, and 15-day exposure to seawater containing HBCD at environmentally related concentrations, respectively. The results showed that the activity of most antioxidant enzymes increased, and different trends were detected with exposure time extending. The oxidative stress could be obviously caused in the gills and digestive glands under the experimental conditions. This could provide useful information for toxic risk assessment of environmental pollutant HBCD.

  18. NTP technical report on the toxicology and carcinogenesis studies of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) (CAS No. 1746-01-6) in female Harlan Sprague-Dawley rats (Gavage Studies).

    PubMed

    2006-04-01

    year 2 of the study, and those of 22 ng/kg rats were less than those of the vehicle controls the last 10 weeks of the study. THYROID HORMONE CONCENTRATIONS: Alterations in serum thyroid hormone levels were evaluated at the 14-, 31- and 53-week interim evaluations. At 14 weeks, there were significant decreases in serum total and free thyroxine (T4) levels and increases in serum total triiodothyronine (T3) and thyroid stimulating hormone (TSH). At 31 weeks, there were significant decreases in serum total and free T4 levels and increases in serum total T3 but no significant effect on TSH. At 53 weeks, there were significant decreases in serum total T4 levels and increases in serum total T3. There were no significant effects on total T4 or TSH levels. HEPATIC CELL PROLIFERATION DATA: To evaluate hepatocyte replication, analysis of labeling of replicating hepatocytes with 5-bromo-2'-deoxyuridine was conducted at the 14-, 31-, and 53-week interim evaluations. The hepatocellular labeling index was significantly higher in the 22 ng/kg group compared to vehicle controls at 14 weeks. At the 31-week interim evaluation, the labeling indices in hepatocytes were significantly higher in all dosed groups than in the vehicle controls. At 53 weeks, labeling indices were significantly higher in the 46 and 100 ng/kg groups than in the vehicle controls. CYTOCHROME P450 ENZYME ACTIVITIES: To evaluate the expression of known dioxin-responsive genes, CYP1A1-associated 7-ethoxyresorufin-O-deethylase (EROD) activity and CYP1A2-associated acetanilide-4-hydroxylase (A4H) activity were evaluated at 14, 31, and 53 weeks. In addition, pentoxyresorufin-O-deethylase (PROD) activity was analyzed. Hepatic EROD, PROD, and A4H activities were significantly higher in all dosed groups relative to vehicle controls at the 14-, 31-, and 53-week interim evaluations. Pulmonary EROD was also significantly higher in all dosed groups compared to vehicle controls at 14, 31, and 53 weeks. DETERMINATIONS OF TCDD

  19. 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.

  20. 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

  1. 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.

  2. 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.

  3. Seasonal patterns of polycyclic aromatic hydrocarbons in digestive gland and arm of octopus (Octopus vulgaris) from the Northwest Atlantic.

    PubMed

    Semedo, Miguel; Oliveira, Marta; Gomes, Filipa; Reis-Henriques, Maria Armanda; Delerue-Matos, Cristina; Morais, Simone; Ferreira, Marta

    2014-05-15

    Among organic pollutants existing in coastal areas, polycyclic aromatic hydrocarbons (PAHs) are of great concern due to their ubiquity and carcinogenic potential. The aim of this study was to evaluate the seasonal patterns of PAHs in the digestive gland and arm of the common octopus (Octopus vulgaris) from the Northwest Atlantic Portuguese coast. In the different seasons, 18 PAHs were determined and the detoxification capacity of the species was evaluated. Ethoxyresorufin O-deethylase (EROD) and ethoxycoumarin O-deethylase (ECOD) activities were measured to assess phase I biotransformation capacity. Individual PAH ratios were used for major source (pyrolytic/petrogenic) analysis. Risks for human consumption were determined by the total toxicity equivalence approach. Generally, low levels of PAHs were detected in the digestive gland and in the arm of octopus, with a predominance of low molecular over high molecular weight compounds. PAHs exhibited seasonality in the concentrations detected and in their main emission sources. In the digestive gland, the highest total PAH levels were observed in autumn possibly related to fat availability in the ecosystem and food intake. The lack of PAH elimination observed in the digestive gland after captivity could be possibly associated to a low biotransformation capacity, consistent with the negligible/undetected levels of EROD and ECOD activity in the different seasons. The emission sources of PAHs found in the digestive gland varied from a petrogenic profile observed in winter to a pyrolytic pattern in spring. In the arm, the highest PAH contents were observed in June; nevertheless, levels were always below the regulatory limits established for food consumption. The carcinogenic potential calculated for all the sampling periods in the arm were markedly lower than the ones found in various aquatic species from different marine environments. The results presented in this study give relevant baseline data for environmental

  4. Seasonal patterns of polycyclic aromatic hydrocarbons in digestive gland and arm of octopus (Octopus vulgaris) from the Northwest Atlantic.

    PubMed

    Semedo, Miguel; Oliveira, Marta; Gomes, Filipa; Reis-Henriques, Maria Armanda; Delerue-Matos, Cristina; Morais, Simone; Ferreira, Marta

    2014-05-15

    Among organic pollutants existing in coastal areas, polycyclic aromatic hydrocarbons (PAHs) are of great concern due to their ubiquity and carcinogenic potential. The aim of this study was to evaluate the seasonal patterns of PAHs in the digestive gland and arm of the common octopus (Octopus vulgaris) from the Northwest Atlantic Portuguese coast. In the different seasons, 18 PAHs were determined and the detoxification capacity of the species was evaluated. Ethoxyresorufin O-deethylase (EROD) and ethoxycoumarin O-deethylase (ECOD) activities were measured to assess phase I biotransformation capacity. Individual PAH ratios were used for major source (pyrolytic/petrogenic) analysis. Risks for human consumption were determined by the total toxicity equivalence approach. Generally, low levels of PAHs were detected in the digestive gland and in the arm of octopus, with a predominance of low molecular over high molecular weight compounds. PAHs exhibited seasonality in the concentrations detected and in their main emission sources. In the digestive gland, the highest total PAH levels were observed in autumn possibly related to fat availability in the ecosystem and food intake. The lack of PAH elimination observed in the digestive gland after captivity could be possibly associated to a low biotransformation capacity, consistent with the negligible/undetected levels of EROD and ECOD activity in the different seasons. The emission sources of PAHs found in the digestive gland varied from a petrogenic profile observed in winter to a pyrolytic pattern in spring. In the arm, the highest PAH contents were observed in June; nevertheless, levels were always below the regulatory limits established for food consumption. The carcinogenic potential calculated for all the sampling periods in the arm were markedly lower than the ones found in various aquatic species from different marine environments. The results presented in this study give relevant baseline data for environmental

  5. Use of octopus as a bioindicator species: Baseline studies

    SciTech Connect

    Holdway, D.A.; Butty, J.S.; Brennan, S.E.; Ahokas, J.T.

    1995-12-31

    The Australian octopus Octopus pallidus, is abundant, territorial, has a large digestive gland. This study was undertaken to assess octopii as a potential bioindicator species by establishing the efficacy of capturing octopi using traplines, and determining the impact of various modifying factors on the activities of digestive gland mixed-function oxidase (MFO) enzymes including ethoxyresorufin O-deethylase (EROD), ethoxycoumarin O-deethylase (ECOD) and total P-450. Trap success rates in Port Phillip Bay were 15--28% for the ``potentially contaminated`` site and 85% for the reference site. Cytochrome P-450 showed significant seasonal differences, with no site or sex differences. Mean ({+-} SE) Autumn P-450 values of 74.8 ({+-}5.5) pmol/mg protein were higher than Winter values of 51.2 ({+-}7.6), which were higher than Spring values of 21.8 ({+-}4.0) pmol/mg protein. Summer P-450 values of 61.4 ({+-} 9.8) pmol/mg protein were only different from Spring values. Mean ({+-} SE) Spring ECOD activity of 3.3 ({+-} 0.7) pmol/min/mg protein was lower than Summer, Autumn and Winter ECOD values of 8.9 ({+-} 1.6) 6.5 ({+-} 1.2) and 8.6 ({+-} 2.3) pmol/min/mg protein respectively. Females had roughly half the ECOD activities of males (3.8 {+-} 0.8 compared to 7.4 {+-} 0.9 pmol/min/mg protein). All octopi digestive gland EROD activities were low (roughly 0.2 pmol/min/mg protein) with no sex, site nor seasonal differences. Potential for using octopus as a bioindicator appears promising but sensitivity to chemical exposure has yet to be determined.

  6. Cytochrome P4501A biomarker indication of oil exposure in harlequin ducks up to 20 years after the Exxon Valdez oil spill.

    PubMed

    Esler, Daniel; Trust, Kimberly A; Ballachey, Brenda E; Iverson, Samuel A; Lewis, Tyler L; Rizzolo, Daniel J; Mulcahy, Daniel M; Miles, A Keith; Woodin, Bruce R; Stegeman, John J; Henderson, John D; Wilson, Barry W

    2010-05-01

    Hydrocarbon-inducible cytochrome P4501A (CYP1A) expression was measured, as ethoxyresorufin-O-deethylase (EROD) activity, in livers of wintering harlequin ducks (Histrionicus histrionicus) captured in areas of Prince William Sound, Alaska, USA, oiled by the 1989 Exxon Valdez spill and in birds from nearby unoiled areas, during 2005 to 2009 (up to 20 years following the spill). The present work repeated studies conducted in 1998 that demonstrated that in harlequin ducks using areas that received Exxon Valdez oil, EROD activity was elevated nearly a decade after the spill. The present findings strongly supported the conclusion that average levels of hepatic EROD activity were higher in ducks from oiled areas than those from unoiled areas during 2005 to 2009. This result was consistent across four sampling periods; furthermore, results generated from two independent laboratories using paired liver samples from one of the sampling periods were similar. The EROD activity did not vary in relation to age, sex, or body mass of individuals, nor did it vary strongly by season in birds collected early and late in the winter of 2006 to 2007, indicating that these factors did not confound inferences about observed differences between oiled and unoiled areas. We interpret these results to indicate that harlequin ducks continued to be exposed to residual Exxon Valdez oil up to 20 years after the original spill. This adds to a growing body of literature suggesting that oil spills have the potential to affect wildlife for much longer time frames than previously assumed.

  7. 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.

  8. Reproductive and biochemical biomarkers in largemouth bass sampled downstream of a pulp and paper mill in Florida

    USGS Publications Warehouse

    Sepulveda, M.S.; Gallagher, E.P.; Wieser, C.M.; Gross, T.S.

    2004-01-01

    The objective of this study was to evaluate the effects of bleached/unbleached kraft mill effluents (B/UKME) on the reproductive parameters of free-ranging Florida largemouth bass (Micropterus salmoides floridanus). The reproductive parameters measured included gonadosomatic index (GSI), histological evaluation of gonads, and plasma concentrations of vitellogenin (VTG), 17??-estradiol, and 11-ketotestosterone (11-KT). Hepatic ethoxyresorufin-O-deethylase (EROD) activity was measured as a marker of exposure to cytochrome P450-inducing agents in these effluents. Endpoints were compared among adult bass sampled from tributary and mainstream effluent-contaminated and reference sites. Females sampled from the site closest to the mill outfall had a significant five-fold increase in EROD activity compared to bass sampled from reference streams. Although sex hormones were significantly reduced in bass from exposed sites, there were no differences in VTG and GSI across sites. The absence of organism-level responses was probably not related to a lack of sensitivity, as previous studies in our laboratory have shown that bass exposed to these effluents exhibit changes in GSI and in other measures associated with reproductive success. In females, inverse relationships were observed between VTG and GSI and EROD activity. These relationship, however, were not consistent within all of the sites studied. Collectively, our findings indicate that hepatic EROD induction is an effective marker of B/UKME exposure in largemouth bass and that it might be associated with antiestrogenic effects in this species. ?? 2003 Elsevier Inc. All rights reserved.

  9. Cytochrome P4501A biomarker indication of oil exposure in harlequin ducks up to 20 years after the Exxon Valdez oil spill.

    PubMed

    Esler, Daniel; Trust, Kimberly A; Ballachey, Brenda E; Iverson, Samuel A; Lewis, Tyler L; Rizzolo, Daniel J; Mulcahy, Daniel M; Miles, A Keith; Woodin, Bruce R; Stegeman, John J; Henderson, John D; Wilson, Barry W

    2010-05-01

    Hydrocarbon-inducible cytochrome P4501A (CYP1A) expression was measured, as ethoxyresorufin-O-deethylase (EROD) activity, in livers of wintering harlequin ducks (Histrionicus histrionicus) captured in areas of Prince William Sound, Alaska, USA, oiled by the 1989 Exxon Valdez spill and in birds from nearby unoiled areas, during 2005 to 2009 (up to 20 years following the spill). The present work repeated studies conducted in 1998 that demonstrated that in harlequin ducks using areas that received Exxon Valdez oil, EROD activity was elevated nearly a decade after the spill. The present findings strongly supported the conclusion that average levels of hepatic EROD activity were higher in ducks from oiled areas than those from unoiled areas during 2005 to 2009. This result was consistent across four sampling periods; furthermore, results generated from two independent laboratories using paired liver samples from one of the sampling periods were similar. The EROD activity did not vary in relation to age, sex, or body mass of individuals, nor did it vary strongly by season in birds collected early and late in the winter of 2006 to 2007, indicating that these factors did not confound inferences about observed differences between oiled and unoiled areas. We interpret these results to indicate that harlequin ducks continued to be exposed to residual Exxon Valdez oil up to 20 years after the original spill. This adds to a growing body of literature suggesting that oil spills have the potential to affect wildlife for much longer time frames than previously assumed. PMID:20821550

  10. Toxicology and carcinogenesis studies of 3,3',4,4'-tetrachloroazobenzene (TCAB) (CAS No. 14047-09-7) in Harlan Sprague-Dawley rats and B6C3F1 mice (gavage studies).

    PubMed

    2010-11-01

    dosed groups of females were significantly less than those of the vehicle controls. The hematology results indicate that TCAB induced a microcytic normochromic responsive anemia in male Sprague-Dawley rats. Serum concentrations of total thyroxine (T4) and free T4 were significantly decreased in a dose-related manner in all dosed groups in both sexes compared to their respective vehicle controls; total triiodothyronine (T3) and thyroid stimulating hormone (TSH) concentrations were generally unaffected. There were no statistically significant differences in the BrdU labeling indices in the liver of males or females exposed to TCAB compared to their respective vehicle controls. Significant induction of hepatic 7-ethoxyresorufin-O-deethylase (EROD) and 7-pentoxyresorufin-O-deethylase activities was observed in all dosed groups of males and females. Significant induction of hepatic acetanilide-4-hydroxylase activity was observed in males exposed to 3 mg/kg or greater and all treated groups of females. EROD activities in the lung generally increased with increasing dose and were significantly greater in all treated groups of males and females compared to their respective vehicle controls. The highest concentrations of TCAB were observed in fat tissue with lower concentrations in the liver and lung. TCAB concentrations were significantly increased in a dose-dependent manner in all tissues from dosed groups relative to vehicle controls. At the end of the 3-month study, absolute and relative liver weights were significantly greater than those of the vehicle controls in all dosed groups of males and in females administered 10 mg/kg or greater. Absolute and relative lung weights were significantly greater in 100 mg/kg males and 3 mg/kg or greater females. Absolute and relative right kidney and spleen weights were generally significantly greater for all dosed groups of males. Absolute thymus weights of 10 mg/kg or greater males and absolute and relative thymus weights of 1 mg/kg or

  11. Toxicology and carcinogenesis studies of a binary mixture of 3,3',4,4',5-pentachlorobiphenyl (PCB 126) (Cas No. 57465-28-8) and 2,3',4,4',5-pentachlorobiphenyl (PCB 118) (Cas No. 31508-00-6) in female Harlan Sprague-Dawley rats (gavage studies).

    PubMed

    2006-11-01

    TEQ/kg at 53 weeks. Cytochrome P450 Enzyme Activities: CYP1A1-associated 7-ethoxyresorufin-O-deethylase (EROD) and CYP1A2-associated acetanilide-4-hydroxylase (A4H) activities were evaluated at the 14-, 31-, and 53-week interim evaluations to evaluate the expression of known dioxin-responsive genes. In addition, CYP2B-associated pentoxyresorufin-O-deethylase (PROD) activity was also analyzed. Hepatic and pulmonary EROD (CYP1A1) activity, hepatic A4H (CYP1A2) activity, and hepatic PROD (CYP2B1) activity were significantly greater in all dosed groups compared to the vehicle controls at weeks 14, 31, and 53. Determinations of PCB 126 and PCB 118 Concentrations in Tissues: The tissue disposition of PCB 126 and PCB 118 was analyzed in the liver, lung, fat, and blood of up to 10 rats in each group at the 14-, 31-, and 53-week interim evaluations, except for the 360 ng TEQ/kg group at 53 weeks. The tissue disposition of PCB 126 and PCB 118 was also analyzed in 10 rats per group at the end of the 2-year study in the vehicle control, 7, 22, and 72 ng TEQ/kg core study groups and the 360 ng TEQ/kg stop-exposure group. Detectable concentrations of PCB 126 and PCB 118 were observed in the liver, fat, lung, and blood. The highest levels of PCB 126 were seen in the liver whereas the highest levels of PCB 118 were seen in the fat. In general, tissue concentrations increased with increasing doses of the mixture and increasing duration of exposure. Hepatic levels of PCB 126 and PCB 118 in the 72 ng TEQ/kg group at the end of the 2-year study were 284 ng/g and 3,769 ng/g, respectively. On a TCDD equivalents basis this corresponds to 28 ng TEQ/g and 0.4 ng TEQ/g for PCB 126 and PCB 118, respectively. Cessation of administration of the mixture in the stop-exposure group led to declines in the tissue concentrations of both PCB 126 and PCB 118 to levels comparable to those observed in the 7 ng TEQ/kg group at the end of the 2-year study. Pathology and Statistical Analyses: At 14, 31, and

  12. NTP toxicology and carcinogenesis studies of 3,3',4,4',5-pentachlorobiphenyl (PCB 126) (CAS No. 57465-28-8) in female Harlan Sprague-Dawley rats (Gavage Studies).

    PubMed

    2006-01-01

    ENZYME ACTIVITIES: To evaluate the expression of known dioxin-responsive genes, CYP1A1 associated 7-ethoxyresorufin-O-deethylase (EROD) activity and CYP1A2-associated acetanilide 4-hydroxylase (A-4-H) activity were evaluated at the 14-, 31-, and 53-week interim evaluations. In addition, CYP2B associated pentoxyresorufin-O-deethylase (PROD) activity was also analysed. Hepatic PROD (CYP2B1) and hepatic and pulmonary EROD (CYP1A1) activity were significantly greater in all dosed groups than in vehicle controls at weeks 14, 31, and 53. Hepatic A-4-H (CYP1A2) activity was significantly greater in the 30, 100, 175, 300, 550, and 1,000 ng/kg groups compared to vehicle controls at weeks 14, 31, and 53. DETERMINATIONS of PCB 126 CONCENTRATIONS IN TISSUES: The tissue disposition of PCB 126 was analyzed in the liver, lung, fat, and blood of all rats in vehicle controls and all dosed groups at the 14-, 31-, and 53-week interim evaluations and in 10 rats per group including vehicle controls at the end of the 2-year study (104 weeks). Detectable concentrations of PCB 126 were observed in the liver, fat, lung, and blood. Measurable concentrations of PCB 126 were present in the liver and fat at weeks 31, 53, and 104. Hepatic and fat concentrations increased with increasing doses of PCB 126. Measurable concentrations of PCB 126 were present in vehicle control lung tissue at 53 and 104 weeks. No PCB 126 was observed in the blood from the vehicle control rats. Lung and blood concentrations tended to increase with increasing doses of PCB 126, with a few exceptions. In the stop-exposure group, PCB 126 concentrations in liver and fat were lower than the levels observed in the 30 ng/kg group. In the stop-exposure group, lung tissue PCB 126 concentrations were equivalent to the levels observed in the 30 ng/kg group. In blood from the stop-exposure group, PCB 126 concentrations were equivalent to the levels observed in the 100 ng/kg group. PATHOLOGY AND STATISTICAL ANALYSES: Absolute and

  13. Toxicology and carcinogenesis studies of 3,3',4,4'-tetrachloroazobenzene (TCAB) (CAS No. 14047-09-7) in Harlan Sprague-Dawley rats and B6C3F1 mice (gavage studies).

    PubMed

    2010-11-01

    dosed groups of females were significantly less than those of the vehicle controls. The hematology results indicate that TCAB induced a microcytic normochromic responsive anemia in male Sprague-Dawley rats. Serum concentrations of total thyroxine (T4) and free T4 were significantly decreased in a dose-related manner in all dosed groups in both sexes compared to their respective vehicle controls; total triiodothyronine (T3) and thyroid stimulating hormone (TSH) concentrations were generally unaffected. There were no statistically significant differences in the BrdU labeling indices in the liver of males or females exposed to TCAB compared to their respective vehicle controls. Significant induction of hepatic 7-ethoxyresorufin-O-deethylase (EROD) and 7-pentoxyresorufin-O-deethylase activities was observed in all dosed groups of males and females. Significant induction of hepatic acetanilide-4-hydroxylase activity was observed in males exposed to 3 mg/kg or greater and all treated groups of females. EROD activities in the lung generally increased with increasing dose and were significantly greater in all treated groups of males and females compared to their respective vehicle controls. The highest concentrations of TCAB were observed in fat tissue with lower concentrations in the liver and lung. TCAB concentrations were significantly increased in a dose-dependent manner in all tissues from dosed groups relative to vehicle controls. At the end of the 3-month study, absolute and relative liver weights were significantly greater than those of the vehicle controls in all dosed groups of males and in females administered 10 mg/kg or greater. Absolute and relative lung weights were significantly greater in 100 mg/kg males and 3 mg/kg or greater females. Absolute and relative right kidney and spleen weights were generally significantly greater for all dosed groups of males. Absolute thymus weights of 10 mg/kg or greater males and absolute and relative thymus weights of 1 mg/kg or

  14. Modeling population-level effects of PCBs on largemouth bass using biomarkers

    SciTech Connect

    Jaworska, J.; Rose, K.A.; DeAngelis, D.L.; Adams, M.A.; Bevelheimer, M.

    1994-12-31

    Population-level effects of PCBs on largemouth bass Micropterus salmoides are simulated using a biomarker-based effects model coupled to an individual-based population model. The individual-based population model tracks individual fish through their daily processes of growth, feeding, mortality and spawning and is configured for Southeastern US reservoirs. The effects model uses relationships between biomarker levels and physiological variables of individual fish. PCB effects are imposed using relationships between EROD (7-ethoxyresorufin Odeethylation) activity and growth reduction and EROD levels in spawners and decreased fry survival. EROD activity measures the amount of P-450 cytochrome induced by PCB exposure. Using field observed EROD levels, one year simulations show that sublethal PCB effects on growth can directly result in increased young-of-the-year mortality by causing smaller sized fish at the end of the growing season, which suffer higher overwinter mortality. Imposing both growth and fry mortality effects produces more complicated results. Under some conditions, density-dependent growth due to lower fry survival can potentially offset PCB-induced reductions in growth. This approach provides a framework for quantitatively extrapolating molecular and other sub-organismal bioindicators to the population level.

  15. Relationship between polychlorinated biphenyl 126 treatment and cytochrome P4501A activity in chickens, as measured by in vivo caffeine and ex vivo ethoxyresorufin metabolism

    SciTech Connect

    Feyk, L.A.; Giesy, J.P.; Lambert, G.H.

    1999-09-01

    Cytochrome P4501A (CYPIA) activity is often used as a biomarker of exposure of wildlife to polyhalogenated diaromatic hydrocarbons (PHDHs) and is usually measured ex vivo in liver tissue. A caffeine breath test with radiolabeled substrate ({sup 14}C-CBT) has been developed to measure in vivo avian CYPIA activity. Research goals were to develop stable isotope methods ({sup 13}C-CBT), determine dose-response relationships between caffeine N-demethylation (CNDM) and PHDH exposure, and assess the relative utility of the CBT and ex vivo ethoxyresorufin-O-deethylase (EROD) assay. The {sup 13}C-CBT methods were developed with 20 chickens (Gallus domesticus). Chickens received three intraperitoneal injections of 0, 1, 5, or 50 {micro}g 3,3{prime},4,4{prime},5-pentachlorobiphenyl (PCB 126)/kg body weight, and CNDM was quantified by measurement of {sup 13}CO{sub 2}/{sup 12}CO{sub 2} in expired breath. The {sup 13}C-CBT was not as sensitive or specific as the EROD assay as an indicator of PHDH exposure and effect in birds. Constitutive CNDM of great interindividual variability was observed, and the magnitude of induction was greater for EROD activity than for CNDM (approximately 1,000- and 2-fold, respectively). Variability associated with baseline {sup 13}CO{sub 2}/{sup 12}CO{sub 2} ratios in expired breath reduced the sensitivity of the {sup 13}C-CBT method.

  16. Carrier effects of dosing the h4iie cells with 3,3′,4,4tt´etrachlorobiphenyl (PCB77) in dimethyl sulfoxide or isooctane

    USGS Publications Warehouse

    Yu, Kyung O.; Fisher, Jeff W.; Burton, G. Allen; Tillitt, Donald E.

    1997-01-01

    A rat hepatoma cell line, H4IIE serves as a bioassay tool to assess the potential toxicity of dioxin-like chemicals, including polychlorinated biphenyls (PCB) in environmental samples. PCB exposure to these cells induces cytochrome (CYP) P4501A1 activity in a dose-dependent fashion, thus allowing assessment of mixtures. The objective of this study was to determine the effect of different carriers, dimethyl sulfoxide (DMSO) and isooctane on the concentrations of PCBs in the H411E cells and induction of CYPIA1 activity as measured by ethoxyresorufm O-deethylase (EROD) activity. H4IIE cells were dosed with three micrograms of UL-14C-PCB77/ plate dissolved in DMSO or isooctane, and were harvested at sequential time periods for 4 days. PCB77 concentration and EROD activity were measured in the cells. EROD activity was greater when using DMSO as compared to isooctane, while there was no difference in the distribution of PCB77-derived radioactivities within the cell culture system based upon the carrier solvent used to deliver PCB77.

  17. Inhibitory effects of H2-receptor antagonists on cytochrome P450 in male ICR mice.

    PubMed

    Kim, D H; Kim, E J; Han, S S; Roh, J K; Jeong, T C; Park, J H

    1995-08-01

    1. The present study was undertaken to examine the effects of H2-receptor antagonists including newly developed mifentidine derivatives, IY-80843 and IY-80845, on cytochrome P450(P450) in vitro and in vivo. 2. Initially, 3-methylcholanthrene-, phenobarbital-, ethanol- and dexamethasone-induced liver microsomes were prepared from male ICR mice to study in vitro effects of above chemicals on ethoxyresorufin O-deethylase(EROD), pentoxyresorufin O-dealkylase(PROD), p-nitrophenol hydroxylase and erythromycin N-demethylase(ERDM) activities, respectively. It was found that histamine, cimetidine and famotidine were not inhibitory to four enzyme activities. Meanwhile, mifentidine slightly inhibited EROD and PROD activities and its derivatives IY-80843 and IY-80845 strongly inhibited PROD, EROD and ERDM activities. 3. Prolongation of hexobarbital-induced sleeping time was determined in male ICR mice to confirm in vitro inhibitory effects of mifentidine and its derivatives in vivo. It was observed that cimetidine, mifentidine, IY-80843 and IY-80845 caused dose-dependent increases in the sleeping time, indicating the inhibition of P450 responsible for hexobarbital metabolism. 4. It was concluded that mifentidine and its derivatives are P450 inhibitors and that our newly synthesized IY-80843 is most inhibitory. 5. The present results indicate that mifentidine and its derivatives not only antagonise the H2-receptor but also inhibit P450 enzymes. PMID:7576828

  18. A toxic equivalency factor scale for polychlorinated dibenzofurans

    USGS Publications Warehouse

    Tysklind, M.; Tillitt, D.; Eriksson, L.; Lundgren, K.; Rappe, C.

    1994-01-01

    The ethoxyresorufin O-deethylase (EROD) induction of 20 polychiorinated dibenzofurans (PCDFs) was examined in the H4IIE rat hepatoma cell bioassay. The selection of the compounds tested was based on a multivariate chemical characterization laying the groundwork for covering the whole chemical series of PCDFs. The EROD induction potency was found to vary in ED50 values from 25 to 100,000,000 pg/mg, i.e., nearly seven orders of magnitude. The response of the bioassay was calibrated against the 2,3,7,8-tetrachlorodibenzo-p-dioxin, enabling the corresponding toxic equivalency factors (TEFs) to be calculated. In order to establish a quantitative structure-activity relationship (QSAR) for the TEF values, 37 physicochemical descriptor variables were used to chemically characterize the 87 tetra- to octachlorinated PCDFs. Using partial least-squares modeling on a training set of 10 congeners, a QSAR model with sound predictive power was obtained. The QSAR model was validated with a validation set of additional 10 congeners. The predicted TEFs indicate that a large number of congeners are potent EROD inducers.

  19. Stock-specific variation of trophic position, diet and environmental stress markers in Atlantic salmon Salmo salar during feeding migrations in the Baltic Sea.

    PubMed

    Vuori, K; Kiljunen, M; Kanerva, M; Koljonen, M-L; Nikinmaa, M

    2012-11-01

    This study investigated stock-specific variation in selected ecophysiological variables during the feeding migrations of Atlantic salmon Salmo salar in the Baltic Sea. Oxidative stress biomarkers and EROD (ethoxyresorufin-O-deethylase, Cyp1A enzyme) activity were used as indicators of possible environmental stress and stable isotopes as determinants of diet and trophic position. Latvian S. salar stocks Daugava and Gauja had distinct stable-isotope signatures compared to the other stocks, indicating differences in migration patterns, residency or arrival times, or dietary specialization among stocks. Salmo salar originating from Daugava and Gauja also had lower catalase enzyme activity than the other stocks. Post-smolts originating from rivers of the Gulf of Finland had elevated EROD activities compared to fish of the same age from Bothnian Bay rivers, which could indicate exposure to organochlorine pollutants. No other stock-specific differences in oxidative stress biomarkers were found. The study demonstrates how genetic, oxidative stress biomarker, EROD and stable-isotope data may be combined to study trophic position, prey prevalence and environmental stress of mixed S. salar stocks foraging in the sea.

  20. Biomarkers of PAH exposure in an intertidal fish species from Prince William Sound, Alaska: 2004-2005.

    PubMed

    Huggett, Robert J; Neff, Jerry M; Stegeman, John J; Woodin, Bruce; Parker, Keith R; Brown, John S

    2006-10-15

    Polycyclic aromatic hydrocarbon (PAH) exposure biomarkers were measured in high cockscomb prickleback (Anoplarchus purpurescens) fish collected from both previously oiled and unoiled shore in Prince William Sound (PWS), Alaska, to test the hypothesis that fish living in the nearshore environment of the sound were no longer being exposed to PAH from the Exxon Valdez oil spill. Pricklebacks spend their entire lives in the intertidal zone of rocky shores with short-term movements during feeding and breeding restricted to an area of about 15 meters in diameter. Fish were assayed for the PAH exposure biomarkers, bile fluorescent aromatic compounds (FAC), and liver ethoxyresorufin O-deethylase (EROD) activity (a measure of cytochrome P450 1A (CYP1A) monooxygenase activity). Bile FAC concentrations and EROD activities were low and not significantly different in fish from previously oiled and unoiled sites. The similar low EROD activity and bile FAC concentrations in fish from oiled and unoiled shores, supports the hypothesis that these low-level biomarker responses were not caused by exposure of the fish to residues of the spilled oil. PMID:17120588

  1. The sublethal effects of petroleum refinery effluents: Mixed function oxygenase (MFO) induction in rainbow trout

    SciTech Connect

    Sherry, J.; Scott, B.; Parrott, J.; Hodson, P.; Rao, S.

    1995-12-31

    Canada uses a single biological parameter which is based on the ability of rainbow trout (Oncorhynchus mykiss) to survive a 24 hour exposure to assess and regulate the toxicity of refinery effluents. The acute toxicity of Canadian refinery effluents is generally well controlled. Long term exposures to sublethal toxicants, which are not covered by the current regulations, could have adverse ecological effects. Since PAHs, such as benzo(a)pyrene, can occur in refinery effluents, the authors tested the hypothesis that refinery effluents can induce mixed-function oxygenase measured as ethoxyresorufin-O-deethylase activity (EROD) activity in fish. Two end of pipe effluent samples were collected from each of four Ontario refineries. All effluents induced EROD activity in young trout in a dose dependent manner. The EROD parameter has potential as a bioindicator of exposure to refinery effluents. The samples were also tested for toxicity to fathead minnow (Pimephales promelas) larvae and to a fish cell line (Ictalurus nebulosus). Fathead minnow growth was significantly reduced by six out of eight samples, and larval survival was affected by one sample. The in vitro data were less consistent: weak toxicity was detected in some samples but the dose response relationship was poor. Direct acting mutagens were detected in two effluents using the Ames Fluctuation assay.

  2. 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.

  3. Comparisons of the effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin on chemically impacted and nonimpacted subpopulations of Fundulus heteroclitus. 2: Metabolic considerations

    SciTech Connect

    Prince, R.; Cooper, K.R.

    1995-04-01

    A previous paper reported resistance to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) toxicity in a subpopulation of Fundulus heteroclitus inhabiting the chemically impacted estuary of Newark Bay, New Jersey, as compared to a chemically nonimpacted subpopulation of F. heteroclitus in Tuckerton, New Jersey. This paper reports the results of toxicokinetic and metabolic investigations. The rate of [{sup 3}H]TCDD elimination following a single dermal treatment of [{sup 3}H]TCDD were similar between the Newark and Tuckerton F. heteroclitus subpopulations, as were the capabilities to metabolize TCDD. The Newark F. heteroclitus subpopulation consistently exhibited elevated hepatic P4501A catalytic activity (two- to fivefold), as measured by ethoxyresorufin O-deethylase (EROD), compared to the Tuckerton subpopulation. EROD activity in Newark F. heteroclitus could not be induced by dermally administered [{sup 3}H]TCDD, ranging from 0.020 to 8.0 ng/g [{sup 3}H]TCDD. The Tuckerton fish exhibited a linear increase in EROD activity at 96 h following dermal administration of [{sup 3}H]TCDD, ranging from 0.80 to 8.0 ng/g [{sup 3}H]TCDD. The maximum mean induction in the Tuckerton fish was 30-fold greater than the Tuckerton vehicle control mean. These data indicate that the Newark fish were resistant to both the toxicity of TCDD and the ability of TCDD to induce P4501A activity, which may imply an alteration in the Ah receptor complex of Newark F. heteroclitus.

  4. Mammalian and teleost cell line bioassay and chemically derived 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalent concentrations in lake trout (Salvelinus namaycush) from Lake Superior and Lake Ontario, North America

    SciTech Connect

    Whyte, J.J.; Heuvel, M.R. van den; Clemons, J.H.; Dixon, D.G.; Bols, N.C.; Huestis, S.Y.; Servos, M.R.

    1998-11-01

    For livers of lake trout from three Great Lakes sites, the 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) equivalent concentrations (TEQs) were determined in four ways. Bioassay-derived (BD) TEQs were measured with rat (H4IIE) and rainbow trout (RTL-W1) cell lines, and chemistry-derived (CD) TEQs were calculated with TCDD equivalency factors (TEFs) derived with H4IIE and RTL-W1. Generally, BD-TEQs and CD-TEQs for individual samples did not differ significantly for either H4IIE or RTL-W1, indicating that all of the AhR-active compounds in a sample were accounted for by the congener analysis and that these compounds acted in an additive fashion in both mammalian and piscine systems. However, contributions of individual chemicals to overall CD-TEQs differed with H4IIE and RTL-W1 TEFs, and for some individual samples. TEQs did depend on the method used. Hepatic TEQs and ethoxyresorufin-O-deethylase (EROD) levels differed significantly between sites. For TEQs, the order was Glenora > Jackfish Bay > Black Bay; for EROD activity, the order was Jackfish Bay > Glenora = Black Bay. No correlation was found between hepatic TEQs and EROD activity, which suggests that the two measurements are evaluating different but related consequences of contaminant exposure.

  5. Oxidative stress in Nile tilapia (Oreochromis niloticus) and armored catfish (Pterygoplichthys anisitsi) exposed to diesel oil.

    PubMed

    Nogueira, Lílian; Rodrigues, Aline Cristina Ferreira; Trídico, Camila Pereira; Fossa, Carlos Eduardo; de Almeida, Eduardo Alves

    2011-09-01

    Considering that diesel oil is one of the most common aquatic contaminants, we compare the oxidative stress between two species of fish with different habitats (Pterygoplichthys anisitsi, benthic and Oreochromis niloticus, nektonic) exposed to diesel oil. Malondialdehyde concentrations (MDA) and the activities of ethoxyresorufin-O-deethylase (EROD), glutathione S-transferase (GST), catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidase were all analyzed in the fishes' livers and gills after 2 and 7 days of exposure to different concentrations of diesel (0.1 and 0.5 mL/L). In the tilapia, MDA levels and the activities of EROD and GST activity in the liver, as well as MDA levels and the activities of GST and SOD in the gill had statistically significant differences between the treatments and between the times of exposure. For the catfish, the same occurred in the case of MDA, EROD, and SOD in the liver and in CAT and SOD in the gills. There were significant differences in the enzyme activity and lipid peroxidation between the species. Although the activity of most enzymes seemed to be more expressive and responsive to diesel in O. niloticus, diesel oil also caused significant effects on oxidative stress parameters in P. anisitsi, even though this species is benthic and thus has less access to insoluble fractions of diesel oil. Therefore, both species can be used as sentinel organisms in environmental biomonitoring of diesel contamination.

  6. Sequencing and characterization of mixed function monooxygenase genes CYP1A1 and CYP1A2 of Mink (Mustela vison) to facilitate study of dioxin-like compounds

    SciTech Connect

    Zhang Xiaowei; Moore, Jeremy N.; Newsted, John L.; Hecker, Markus Zwiernik, Matthew J.; Jones, Paul D.; Bursian, Steven J.

    2009-02-01

    As part of an ongoing effort to understand aryl hydrocarbon receptor (AhR) mediated toxicity in mink, cDNAs encoding for CYP1A1 and the CYP1A2 mixed function monooxygenases were cloned and characterized. In addition, the effects of selected dibenzofurans on the expression of these genes and the presence of their respective proteins (P4501A) were investigated, and then correlated with the catalytic activities of these proteins as measured by ethoxyresorufin O-deethylase (EROD) and methoxyresorufin O-deethylase (MROD) activities. The predicted protein sequences for CYP1A1 and CYP1A2 comprise 517 and 512 amino acid residues, respectively. The phylogenetic analysis of the mink CYP1As with protein sequences of other mammals revealed high sequence homology with sea otter, seals and the dog, with amino acid identities ranging from 89 to 95% for CYP1A1 and 81 to 93% for CYP1A2. Since exposure to both 2,3,7,8-Tetrachlorodibenzofuran (TCDF) and 2,3,4,7,8-Pentachlorodibenzofuran (PeCDF) resulted in dose-dependent increases of CYP1A1 mRNA, CYP1A2 mRNA and CYP1A protein levels an underlying AhR-mediated mechanism is suggested. The up-regulation of CYP1A mRNA in liver was more consistent to the sum adipose TEQ concentration than to the liver TEQ concentration in minks treated with TCDF or PeCDF. The result suggested that the hepatic-sequestered fraction of PeCDF was biologically inactive to the induction of CYP1A1 and CYP1A2.

  7. Oil shale processing as a source of aquatic pollution: monitoring of the biologic effects in caged and feral freshwater fish.

    PubMed Central

    Tuvikene, A; Huuskonen, S; Koponen, K; Ritola, O; Mauer, U; Lindström-Seppä, P

    1999-01-01

    The biologic effects of the oil shale industry on caged rainbow trout (Oncorhynchus mykiss) as well as on feral perch (Perca fluviatilis) and roach (Rutilus rutilus) were studied in the River Narva in northeast Estonia. The River Narva passes the oil shale mining and processing area and thus receives elevated amounts of polycyclic aromatic hydrocarbons (PAHs), heavy metals, and sulfates. The effects of the chemical load were monitored by measuring cytochrome P4501A (CYP1A)-dependent monooxygenase (MO) activities [7-ethoxyresorufin O-deethylase and aryl hydrocarbon hydroxylase (AHH)] as well as conjugation enzyme activities [glutathione S-transferase (GST) and UDP-glucuronosyltransferase] in the liver of fish. CYP1A induction was further studied by detecting the amount and occurrence of the CYP1A protein. Histopathology of tissues (liver, kidney, spleen, and intestine) and the percentage of micronuclei in fish erythrocytes were also determined. Selected PAHs and heavy metals (Cd, Cu, Hg, and Pb) were measured from fish muscle and liver. In spite of the significant accumulation of PAHs, there was no induction of MO activities in any studied fish species. When compared to reference samples, AHH activities were even decreased in feral fish at some of the exposed sites. Detection of CYP1A protein content and the distribution of the CYP1A enzyme by immunohistochemistry also did not show extensive CYP1A induction. Instead, GST activities were significantly increased at exposed sites. Detection of histopathology did not reveal major changes in the morphology of tissues. The micronucleus test also did not show any evidence of genotoxicity. Thus, from the parameters studied, GST activity was most affected. The lack of catalytic CYP1A induction in spite of the heavy loading of PAHs was not studied but has been attributed to the elevated content of other compounds such as heavy metals, some of which can act as inhibitors for MOs. Another possible explanation of this lack of

  8. Towards science-based sediment quality standards-Effects of field-collected sediments in rainbow trout (Oncorhynchus mykiss).

    PubMed

    Brinkmann, Markus; Eichbaum, Kathrin; Reininghaus, Mathias; Koglin, Sven; Kammann, Ulrike; Baumann, Lisa; Segner, Helmut; Zennegg, Markus; Buchinger, Sebastian; Reifferscheid, Georg; Hollert, Henner

    2015-09-01

    Sediments can act as long-term sinks for environmental pollutants. Within the past decades, dioxin-like compounds (DLCs) such as polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), polychlorinated biphenyls (PCBs), and polycyclic aromatic hydrocarbons (PAHs) have attracted significant attention in the scientific community. To investigate the time- and concentration-dependent uptake of DLCs and PAHs in rainbow trout (Oncorhynchus mykiss) and their associated toxicological effects, we conducted exposure experiments using suspensions of three field-collected sediments from the rivers Rhine and Elbe, which were chosen to represent different contamination levels. Five serial dilutions of contaminated sediments were tested; these originated from the Prossen and Zollelbe sampling sites (both in the river Elbe, Germany) and from Ehrenbreitstein (Rhine, Germany), with lower levels of contamination. Fish were exposed to suspensions of these dilutions under semi-static conditions for 90 days. Analysis of muscle tissue by high resolution gas chromatography and mass spectrometry and of bile liquid by high-performance liquid chromatography showed that particle-bound PCDD/Fs, PCBs and PAHs were readily bioavailable from re-suspended sediments. Uptake of these contaminants and the associated toxicological effects in fish were largely proportional to their sediment concentrations. The changes in the investigated biomarkers closely reflected the different sediment contamination levels: cytochrome P450 1A mRNA expression and 7-ethoxyresorufin-O-deethylase activity in fish livers responded immediately and with high sensitivity, while increased frequencies of micronuclei and other nuclear aberrations, as well as histopathological and gross pathological lesions, were strong indicators of the potential long-term effects of re-suspension events. Our study clearly demonstrates that sediment re-suspension can lead to accumulation of PCDD/Fs and PCBs in fish

  9. How flood events affect rainbow trout: evidence of a biomarker cascade in rainbow trout after exposure to PAH contaminated sediment suspensions.

    PubMed

    Brinkmann, Markus; Hudjetz, Sebastian; Kammann, Ulrike; Hennig, Michael; Kuckelkorn, Jochen; Chinoraks, Michelle; Cofalla, Catrina; Wiseman, Steve; Giesy, John P; Schäffer, Andreas; Hecker, Markus; Wölz, Jan; Schüttrumpf, Holger; Hollert, Henner

    2013-03-15

    Increasing frequency and intensity of flood events are major concerns in the context of climate change. In addition to the direct hydrological implications of such events, potential ecotoxicological impacts are of increasing interest. It is vital to understand mechanisms of contaminant uptake from suspended particulate matter (SPM) and related effects in aquatic biota under realistic conditions. However, little is known about these processes. Due to recent changes in climate, during summer temperatures of German rivers frequently exceed 25°C. Effects of re-suspension of sediments on biota under elevated temperature regimes are likely to differ from those under lower temperature regimes. To elucidate this differential response of aquatic vertebrates, rainbow trout were exposed to suspensions of sediment from the Rhine River that was spiked with a mixture of polycyclic aromatic hydrocarbons (PAH). The experiments were conducted under two different temperature regimes (24°C or 12°C). Physicochemical parameters, including concentration of PAHs in SPM, and biomarkers in fish (biliary PAH metabolites, 7-ethoxyresorufin O-deethylase activity, lipid peroxidation (LPO), mRNA expression of some genes and micronuclei) were measured over the course of a 12d study. Concentrations of pyrene and phenanthrene decreased over time, while no decrease was observed for chrysene and benzo[a]pyrene. The biomarker cascades, more specifically the temporal dynamics of biomarker reactions, did not only show quantitative differences (i.e. different induction intensity or rate of biomarker responses) at the two temperatures but also qualitative differences, i.e. different biomarker responses were observed. A slight significant increase of biliary metabolites in fish was observed in un-spiked sediment at 24°C. In bile of fish exposed to PAH spiked sediment concentrations of 1-hydroxypyrene and 1-hydroxyphenanthrene increased significantly during the first two days, and then decreased. At 12

  10. Contribution of Priority PAHs and POPs to Ah Receptor-Mediated Activities in Sediment Samples from the River Elbe Estuary, Germany

    PubMed Central

    Otte, Jens C.; Keiter, Steffen; Faßbender, Christopher; Higley, Eric B.; Rocha, Paula Suares; Brinkmann, Markus; Wahrendorf, Dierk-Steffen; Manz, Werner; Wetzel, Markus A.; Braunbeck, Thomas; Giesy, John P.; Hecker, Markus; Hollert, Henner

    2013-01-01

    The estuary of the River Elbe between Hamburg and the North Sea (Germany) is a sink for contaminated sediment and suspended particulate matter (SPM). One major concern is the effect of human activities on the hydrodynamics, particularly the intensive dredging activities in this area that may result in remobilization of sediment-bound pollutants. The aim of this study was to identify pollutants contributing to the toxicological risk associated with re-suspension of sediments in the Elbe Estuary by use of an effect-directed analysis that combines chemical and biological analyses in with specific fractionation techniques. Sediments were collected from sites along the Elbe Estuary and a site from a small harbor basin of the Elbe Estuary that is known to be polluted. The sixteen priority EPA-PAHs were quantified in organic extracts of sediments. In addition, dioxin equivalents of sediments were investigated by use of the 7-ethoxyresorufin O-deethylase assay with RTL-W1 cells and the Ah receptor-mediated luciferase transactivation assay with H4IIE-luc cells. Quantification of the 16 priority PAHs revealed that sediments were moderately contaminated at all of the sites in the Elbe River Estuary (<0.02–0.906 µg/g dw). Sediments contained relatively small concentrations of dioxin equivalents (Bio-TEQ) with concentrations ranging from 15.5 to 322 pg/g dw, which were significantly correlated with dioxin equivalents calculated based on toxicity reference values and concentrations of PAH. The concentration of Bio-TEQ at the reference site exceeded 200,000 pg/g dw. In a potency balance the 16 PAHs explained between 47 and 118% of the Bio-TEQ in the luciferase assay, which can be explained by the constant input of PAHs bound to SPM from the upper course of the Elbe River into its estuary. Successful identification of a significant portion of dioxin-like activity to priority PAHs in complex environmental samples such as sediments has rarely been reported. PMID:24146763

  11. Testing the ecotoxicology of vegetable versus mineral based lubricating oils: 2. Induction of mixed function oxidase enzymes in barramundi, Lates calcarifer, a tropical fish species.

    PubMed

    Mercurio, Philip; Burns, Kathryn A; Cavanagh, Joanne

    2004-05-01

    An increasing number of vegetable-based oils are being developed as environmentally friendly alternatives to petroleum products. However, toxicity towards key tropical marine species has not been investigated. In this study we used laboratory-based biomarker induction experiments to compare the relative stress of a vegetable-based lubricating oil for marine 2-stroke engines with its mineral oil-based counterpart on tropical fish. The sub-lethal stress of 2-stoke outboard lubricating oils towards the fish Lates calcarifer (barramundi) was examined using liver microsomal mixed function oxidase (MFO) induction assays. This study is the first investigation into the use of this key commercial species in tropical North Queensland, Australia in stress assessment of potential hydrocarbon pollution using ethoxyresorufin O-deethylase (EROD) induction. Our results indicated that barramundi provide a wide range of inducible rates of EROD activity in response to relevant organic stressors. The vegetable- and mineral-based lubricants induced significant EROD activity at 1.0 mg kg(-1) and there was no significant difference between the two oil treatments at that concentration. At increasing concentrations of 2 and 3 mg kg(-1), the mineral-based lubricant resulted in slightly higher EROD activity than the vegetable-based lubricant. The EROD activity of control and treated barramundi are found to be within ranges for other species from temperate and tropical environments. These results indicate that vegetable-based lubricants may be less stressful to barramundi than their mineral counterparts at concentrations of lubricant > or =2 mg kg(-1). There is great potential for this species to be used in the biomonitoring of waterways around tropical North Queensland and SE Asia.

  12. Differential potency of atropisomers of polychlorinated biphenyls on cytochrome P450 induction and uroporphyrin accumulation in the chick embryo hepatocyte culture.

    PubMed

    Rodman, L E; Shedlofsky, S I; Mannschreck, A; Püttmann, M; Swim, A T; Robertson, L W

    The atropisomers of 2,2',3,4,6-pentachlorobiphenyl (PeCB), 2,2',3,4,4',6-hexachlorobiphenyl (HeCB), and 2,2',3,3',4,4',6,6'-octachlorobiphenyl (OCB) were studied in the chick embryo hepatocyte culture to determine if chirality plays a role in the recognition events associated with the induction of cytochromes P450 and the accumulation of uroporphyrin (URO). Concentration-related induction of cytochrome P450 content, ethoxyresorufin-O-deethylase (EROD) and benzphetamine N-demethylase (BPDM) activities were measured. The rank order of potency for total cytochrome P450 induction was HeCB greater than OCB greater than or equal to PeCB. The (+)- and (-)-enantiomers of PeCB and OCB were of equal potencies as inducers of cytochromes P450, whereas the (+)-HeCB was greater than the (-)-HeCB. HeCB was a much more potent inducer of EROD activity than was either PeCB or OCB. EROD activity was induced to a much greater extent by the (+)-enantiomers of all compounds, with the (-)-enantiomers of PeCB and OCB being inactive. BPDM activity was induced by all three compounds in the order of OCB greater than or equal to HeCB greater than PeCB. The (-)-enantiomers were more potent inducers of BPDM activities than were the (+)-enantiomers, except for HeCB, in which the (+)- was more potent than the (-)-enantiomer. Analysis of porphyrin accumulation in cultures treated with delta-aminolevulinic acid revealed that (+)-HeCB caused the greatest percent URO accumulation, which also correlated with the greatest increase in EROD activity. All other enantiomers caused up to 47% URO accumulation, which did not correlate with an increase in EROD activity.

  13. Highly purified hexachlorobenzene induces cytochrome P4501A in primary cultures of chicken embryo hepatocytes

    SciTech Connect

    Mundy, Lukas J.; Jones, Stephanie P.; Crump, Doug; Herve, Jessica C.; Konstantinov, Alex; Utley, Fiona; Potter, David; Kennedy, Sean W.

    2010-11-01

    Some uncertainty exists regarding the purity of hexachlorobenzene (HCB) used in past toxicity studies. It has been suggested that reported toxic and biochemical effects initially attributed to HCB exposure may have actually been elicited by contamination of HCB by polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs). Herein, primary cultures of chicken embryo hepatocytes (CEH) were used to compare the potencies of two lots of reagent-grade hexachlorobenzene (HCB-old [HCB-O] and HCB-new [HCB-N]), highly purified HCB (HCB-P) and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) as inducers of ethoxyresorufin O-deethylase (EROD) activity, cytochrome P4501A4 (CYP1A4) messenger ribonucleic acid (mRNA) and CYP1A5 mRNA. The study also compared the EROD- and CYP1A4/5 mRNA-inducing potencies of HCB to the potencies of two mono-ortho substituted polychlorinated biphenyls (PCBs), 2,3,3',4,4'-pentachlorobiphenyl (PCB 105) and 2,3'4,4',5-pentachlorobiphenyl (PCB 118). HCB-O, HCB-N and HCB-P all induced EROD activity and up-regulated CYP1A4 and CYP1A5 mRNAs. Induction was not caused by contamination of HCB with PCDDs or PCDFs. Based upon a comparison of the EC{sub 50} and EC{sub threshold} values for EROD and CYP1A4/5 mRNA concentration-response curves, the potency of HCB relative to the potency of TCDD was 0.0001, and was similar to that of PCB 105 and PCB 118. The maximal EROD activity and CYP1A4/5 mRNA expression differed greatly between HCB and TCDD, and may contribute to an overestimation of the ReP value calculated for highly purified HCB.

  14. Inhibition of gizzard shade (Dorosoma cepedianum) P4501A activity by in vivo and in vitro administration of clotrimazole

    SciTech Connect

    Levine, S.; Czosnyka, H.; Oris, J.

    1995-12-31

    The ability of the 1-substituted imidazole agent clotrimazole to inhibit in vivo and in vitro hepatic microsomal ethoxyresorufin O-deethylase (EROD) activity was investigated using gizzard shad (Dorosoma cepedianum) pre-treated with clotrimazole and then given waterborne exposures of benzo[a]pyrene (BaP). Gizzard shad pre-treated with 50 mg clotrimazole/kg and then exposed for 1 or 3 d to BaP (0.86 {micro}g/L) had significantly lower hepatic EROD activity compared to fish that were exposed to BaP alone. Following 1 and 3 d of BaP exposure, groups pre-treated with clotrimazole had 7% and 28% of the EROD activity respectively relative to groups exposed to BaP alone. In addition, there was 8x and 11x more parent BaP in whole-fish extracts from gizzard shad pre-treated with clotrimazole after 1 and 3 d of BaP exposure, respectively, compared to fish exposed to BaP alone. Clotrimazole produced a ``type 11`` binding spectral complex with BaP-treated microsomes and was an effective in vitro inhibitor of EROD activity in micromolar concentrations. The IC{sub 50} for EROD activity was 0.57 {micro}M clotrimazole. The mechanism of inhibition by clotrimazole was determined to be noncompetitive (mixed type) using kinetics experiments. Noncompetitive inhibition of monooxygenase activity is believed to arise from the interaction created via the non-bonded electrons of the nitrogen in the imidazole ring with the name moiety of cytochrome P450, resulting in inhibition of enzymatic activity. The high inhibitory potency of clotrimazole on P4501A catalyzed reactions may prove valuable for its use as a probe in determining whether chemical toxicity is manifested through a cytochrome P450-mediated pathway.

  15. 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

  16. Temporal induction of cytochrome P450 1A in the mirror carp (Cyprinus carpio) after administration of several polycyclic aromatic hydrocarbons

    SciTech Connect

    Weiden, M.E.J. Van Der; Hanegraaf, F.H.M.; Seinen, W.; Berg, M. Van Den . Research Inst. of Toxicology); Eggens, M.L. . Dept. of Ecotoxicology); Celander, M. . Dept. of Zoophysiology)

    1994-05-01

    High inductions of 7-ethoxyresorufin O-deethylation (EROD) activities, cytochrome P450 1A protein levels (P4501A), and total cytochrome P450 content (P450) were observed 1, 2, 5, and 14 d after a single i.p. injection of 99.5 [mu]mol/kg benzo[a]pyrene (BaP) and chrysene (Chrys). The highest inductions in EROD activities and P450 1A protein levels were seen 2 d after treatment, approximately 35- and 11-fold relative to the controls. Less pronounced increase of EROD activities and P4501A protein levels, approximately 3- to 10-fold and 6-fold, respectively, were observed after treatments with equimolar concentrations of fluoranthenes (Fluor) and pyrene (Pyr). Benzo[ghi]perylene (BghiP) and the carrier dimethyl sulfoxide (DMSO) did not affect these parameters. The highest concentrations of PAHs in the liver, equivalent to 2 to 25% of the dose, were found 1 or 2 d after treatment. The highest percentage of the dose in the liver was observed for Chrys, followed by BghiP, BaP, Fluor, and Pyr. Poor correlations were found between hepatic concentrations of PAHs and P450 1A increases, which might be attributed to the rapid metabolism of these compounds.

  17. Structures of pulp-mill-related inducers of mixed function oxygenase (MFO) in rainbow trout

    SciTech Connect

    Parrott, J.L.; Hodson, P.V.; Bennie, D.T.; Efler, S.M.; Burnison, B.K.

    1994-12-31

    There are many known inducers of MFO activity in fish, such as polychlorinated dioxins, furans, biphenyls and polyaromatic hydrocarbons (PAHs). Since a specific chemical structure is required for Ah receptor binding to initiate induction, chemical structure is a critical factor controlling potency. Elevated hepatic MFO activity is common in fish downstream of pulp mill effluent discharges. The identity of the MFO-inducer(s) in pulp mill effluents is, as yet, unknown, although initial theories linked dioxins and furans in effluents with induction. The author have extracted effluent from several Canadian pulp mills, and have identified many non-chlorinated compounds with structures similar to known MFO inducers. PAHs such as substituted naphthalenes, chrysene and phenanthrene have been detected in effluent or defoamers used in pulp mils, but none induced ethoxyresorufin-O-deethylase (EROD) activity of rainbow trout (Oncorhynchus mykiss) after 4 d exposures at levels up to 1,000 {micro}g/L. Some multi-ringed compounds found in effluent or sediments from pulp mills induced EROD, while others, such as nonyl phenols, phthalates and benzothioazole showed no induction. These results are expanding the range of known inducers and will aid the development of models relating potency to chemical structure.

  18. Exposure to hydrocarbons 10 years after the Exxon Valdez oil spill: evidence from cytochrome P4501A expression and biliary FACs in nearshore demersal fishes.

    PubMed

    Jewett, Stephen C; Dean, Thomas A; Woodin, Bruce R; Hoberg, Max K; Stegeman, John J

    2002-01-01

    Three biomarkers of hydrocarbon exposure, CYP1A in liver vascular endothelium, liver ethoxyresorufin O-deethylase (EROD), and biliary fluorescent aromatic compounds (FACs), were examined in the nearshore fishes, masked greenling (Hexagrammos octogrammus) and crescent gunnel (Pholis laeta), collected in Prince William Sound, Alaska, 7-10 years after the Exxon Valdez oil spill (EVOS). All biomarkers were elevated in fish collected from sites originally oiled, in comparison to fish from unoiled sites. In 1998, endothelial CYP1A in masked greenling from sites that were heavily oiled in 1989 was significantly higher than in fish collected outside the spill trajectory. In 1999, fishes collected from sites adjacent to intertidal mussel beds containing lingering Exxon Valdez oil had elevated endothelial CYP1A and EROD, and high concentrations of biliary FACs. Fishes from sites near unoiled mussel beds, but within the original spill trajectory, also showed evidence of hydrocarbon exposure, although there were no correlations between sediment petroleum hydrocarbon and any of the biomarkers. Our data show that 10 years after the spill, nearshore fishes within the original spill zone were still exposed to residual EVOS hydrocarbons.

  19. White sucker (Catostomus commersoni) growth and sexual maturation in pulp mill-contaminated and reference rivers

    SciTech Connect

    Gagnon, M.M.; Bussieres, D.; Dodson, J.J. ); Hodson, P.V. )

    1995-02-01

    Induction of hepatic ethoxyresorufin-O-deethylase (EROD) activity and accumulation of chlorophenolic compounds typical of bleached-kraft mill effluent (BKME) in fish sampled downstream of a pulp mill on the St. Maurice River, Quebec, Canada, provided evidence of chemical exposure to BKME. In comparison, fish sampled over the same distances and in similar habitats in a noncontaminated reference river, the Gatineau River, demonstrated low EROD activity and contamination levels. Accelerated growth of white suckers occurred between 2 and 10 years of age in both rivers at downstream stations relative to upstream stations, suggesting the existence of gradients of nutrient enrichment independent of BKME contamination. The impact of BKME exposure was expressed as reduced investment in reproduction, as revealed by greater length at maturity, reduced gonad size, and more variable fecundity. These effects were not obvious in simple upstream-downstream comparisons, but became evident when fish from the uncontaminated Gatineau River showed increased gonadal development and reduced age and size at maturity in response to enhanced growth rates.

  20. Comparing the response of biochemical indicators (biomarkers) and biological indices to diagnose the ecological impact of an oil spillage in a Mediterranean river (NE Catalunya, Spain).

    PubMed

    Damásio, Joana B; Barata, Carlos; Munné, Antoni; Ginebreda, Antoni; Guasch, Helena; Sabater, Sergi; Caixach, Josep; Porte, Cinta

    2007-01-01

    Three biomarkers of hydrocarbon exposure, liver 7-ethoxyresourfin-O-deethylase activity (EROD), fluorescent hydrocarbon compounds (FACs) in bilis, and the liver antioxidant enzyme catalase (CAT) were examined in the autochthonous fish species Barbus meridionalis collected in the river Fluvià (NE Catalunya, Spain) after an oil spillage. Four different locations were sampled, including the impacted site, upstream and downstream sites and a reference site. Biomarker responses were compared with diatom and macroinvertebrate community assemblage metrics (Specific Pollution Sensitivity index - IPS, and Iberian Biological Monitoring Working Party - IBMWP, respectively). Chemical analyses denoted that polycyclic aromatic hydrocarbon levels in sediment were much higher at the impacted site than in downstream reaches. Four fold increase of EROD activity together with increased levels of biliary FACs in barbs collected at the spilled site indicated exposure of inhabiting fish to the oil. Additionally, CAT activity was significantly depressed (four fold) when compared to other stations, thus suggesting that fish collected from the impacted sites could be more susceptible to suffer oxidative stress. Biological indices (particularly that of the diatom community IPS) showed slight significant effects between control and impacted sites, indicating that more tolerant taxa were favoured because of the oil spillage. These results support the need to include biochemical responses measured in local species in monitoring programmes aimed to diagnose specific pollution effects in stressed river ecosystems. PMID:16959291

  1. Assessment of seasonal and sex-related variability of biomarkers in carp (Cyprinus carpio L.) from Karakaya Dam Lake, Turkey.

    PubMed

    Güngördü, Abbas; Ozmen, Murat

    2011-05-01

    This study examines seasonal changes in the activities of selected biomarkers in carp (Cyprinus carpio L.) from Karakaya Dam Lake and evaluates the influence of gender and environmental factors on those activities. Physicochemical characteristics of water were evaluated in the lakewater. Fish were sampled on seasonal basis, and liver ethoxyresorufin-O-deethylase (EROD), glutathione-S-transferase, glutathione reductase, plasma lactate dehydrogenase, aspartate and alanine aminotransferase, and brain acetylcholinesterase (AChE) activities were assayed. Plasma vitellogenin level and hepatosomatic index and condition factors were also determined. Strong seasonal variations were observed but there were no gender differences among selected markers. The highest vitellogenin level of male fish was detected as 606ng/mL which represents the estrogenicity of water in the lake in September 2005. In addition, the seasonal changes of some biomarkers such as EROD and AChE showed that the lake may be at risk of pollution by some xenobiotics arising from agricultural and/or industrial activities.

  2. Biomarkers of exposure of brown bullheads (Ameiurus nebulosus) to contaminants in the lower Great Lakes, North America

    SciTech Connect

    Arcand-Hoy, L.D.; Metcalfe, C.D.

    1999-04-01

    Brown bullheads (Ameiurus nebulosus) from three contaminated sites (Detroit River, Hamilton Harbour, and Black River) and two relatively clean reference sites (Old Woman Creek and Bay of Quinte) in the lower Great Lakes were monitored for several biomarkers of exposure to PAHs. Bullheads from the contaminated sites had elevated hepatosomatic indices, increased ethoxyresorufin-O-deethylase (EROD) activity, decreased hepatic retinoid stores, and a greater incidence of hepatic neoplasms. Fluorescent aromatic compounds (FACs) in the bile were also elevated in bullheads from the Black River and Hamilton Harbour in comparison to fish from reference sites. A correlation was found between reduction of hepatic retinoid stores and induction of hepatic EROD activity in bullheads. Principal component analysis of biomarker data demonstrated that biomarker patterns in Detroit River bullheads were different from those of Black River and Hamilton Harbour bullheads. Biomarkers in fish are useful monitoring tools for detecting contamination of the aquatic environment, but interpretation of results is limited by within- and between-site variability in the responses, some of which may be explained by mobility of the fish. In contaminated areas, bile fluorescent aromatic compounds appear to be the best indicator of recent exposure to polynuclear aromatic hydrocarbons, whereas responses to other biochemical biomarkers appear to be over a longer time period.

  3. Effects of an oil spill in a harbor assessed using biomarkers of exposure in eelpout.

    PubMed

    Sturve, Joachim; Balk, Lennart; Liewenborg, Birgitta; Adolfsson-Erici, Margaretha; Förlin, Lars; Carney Almroth, Bethanie

    2014-12-01

    Oil spills occur commonly, and chemical compounds originating from oil spills are widespread in the aquatic environment. In order to monitor effects of a bunker oil spill on the aquatic environment, biomarker responses were measured in eelpout (Zoarces viviparus) sampled along a gradient in Göteborg harbor where the oil spill occurred and at a reference site, 2 weeks after the oil spill. Eelpout were also exposed to the bunker oil in a laboratory study to validate field data. The results show that eelpout from the Göteborg harbor are influenced by contaminants, especially polycyclic aromatic hydrocarbons (PAHs), also during "normal" conditions. The bunker oil spill strongly enhanced the biomarker responses. Results show elevated ethoxyresorufin-O-deethylase (EROD) activities in all exposed sites, but, closest to the oil spill, the EROD activity was partly inhibited, possibly by PAHs. Elevated DNA adduct levels were also observed after the bunker oil spill. Chemical analyses of bile revealed high concentrations of PAH metabolites in the eelpout exposed to the oil, and the same PAH metabolite profile was evident both in eelpout sampled in the harbor and in the eelpout exposed to the bunker oil in the laboratory study.

  4. Contamination and correlation with toxicity of sediment samples from the Skagerrak and Kattegat

    NASA Astrophysics Data System (ADS)

    Magnusson, K.; Ekelund, R.; Dave, G.; Granmo, Å.; Förlin, L.; Wennberg, L.; Samuelsson, M.-O.; Berggren, M.; Brorström-Lundén, E.

    1996-02-01

    The pollution state in the Skagerrak and Kattegat was investigated by determination of pollutant concentrations and toxicity of sediment samples from 11 stations in the area. A comparison was made with the sediment from a reference site near the Faroe Islands. Polycyclic aromatic hydrocarbons (PAH) and organochlorines were determined in whole sediment and heavy metals and ammonia were analysed in filtered pore water. Toxicity was bioassayed in whole sediment with Nitocra spinipes and Daphnia magna, in pore water with Mytilus edulis larvae and in solvent extracts from sediment with tests measuring etoxyresorufin-O-deethylase (EROD) activity in Oncorhyncus mykiss and rate of denitrification. Sites close to Göteborg and in an area from the Oslo fjord to the Norwegian Trench were most polluted. Sediment from the Faroe Islands was least polluted and also least toxic. Multivariate statistical analysis indicates that the different tests were sensitive to different kinds of pollutants. Effects on mussel larvae correlated strongest with the occurrence of ammonia, manganese, cadmium and PAHs, Nitocra with α-hexachlorocyclohexane (HCH) and p,p'-DDD, Daphnia with arsenic and γ-HCH, fish EROD activity with benzo[ghi]perylene and unknown compounds associated with organic carbon, and denitrification with chlordanes, dieldrin and a few PAHs. The results indicate that sampling sites close to Göteborg are so polluted that harmful effects on the ecosystem probably occur.

  5. Identification of biomarkers responsive to chronic exposure to pharmaceuticals in target tissues of Carcinus maenas.

    PubMed

    Aguirre-Martínez, G V; Del Valls, T A; Martín-Díaz, M L

    2013-01-01

    A 28-day bioassay was performed with Carcinus maenas to evaluate chronic effects caused by exposure to caffeine and ibuprofen (0.1-50 μg L(-1)) in sea water. Lysosomal membrane stability (LMS) was evaluated in hemolymph applying the neutral red retention assay (NRRA); several biomarkers including ethoxyresorufin O-deethylase (EROD), dibenzylfluorescein dealkylase (DBF), glutathione S-transferase (GST), glutathione peroxidase (GPX), lipid peroxidation (LPO) and DNA damage were studied in gill, hepatopancreas, muscle and gonad tissues. In crabs exposed to environmental concentrations of the drugs, retention time was reduced by 50%. EROD and DBFOD activities were induced by caffeine in muscle and hepatopancreas tissues (p < 0.05); GST activity was activated by ibuprofen in gill, hepatopancreas and muscle at the highest concentrations tested (p < 0.05). All tissues showed GPX activity and LPO induction (p < 0.05). Crabs exposed to caffeine and ibuprofen showed evidence of DNA damage mainly in hepatopancreas tissues (p < 0.05). Environmental concentrations of pharmaceuticals induce LMS and the biochemical responses studied in this crab. This methodology is a suitable technique for assessing pharmaceutical toxicity in the marine environment. PMID:23562135

  6. Comparative study of 17 β-estradiol on endocrine disruption and biotransformation in fingerlings and juveniles of Japanese sea bass Lateolabrax japonicus.

    PubMed

    Thilagam, Harikrishnan; Gopalakrishnan, Singaram; Bo, Jun; Wang, Ke-Jian

    2014-08-30

    Estrogenic contaminants in the aquatic environment are associated with endocrine disruption and feminization in fish. The effects of endocrine disrupting chemicals (EDCs) on fish have been well documented. However, very few studies have focused on 17 β-estradiol (E2) and its effects on endocrine system and biotransformation in a single prolonged exposure. This study investigated changes in the levels of serotonin (5-hydroxytryptamine) and acetyl choline esterase (AchE) in brain, cortisol in plasma and Ethoxyresorufin-O-deethylase (EROD) activity in gill of two different size groups (fingerlings and juveniles) of Japanese sea bass (Lateolabrax japonicus) upon exposure to two sub-lethal concentrations (200 and 2000 ng L(-1)) of E2 for 30 d. The results indicate that cortisol level and EROD activity significantly increased in both groups, whereas serotonin level increased in juveniles and decreased in fingerlings due to E2 exposure. The correlation analysis revealed that E2 significantly affected the endocrine and biotransformation systems in both age groups. PMID:24882444

  7. 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

  8. Enoxacin is an inducer of CYP1A2 in rat liver.

    PubMed

    Schulz, T G; Stahlmann, R; Edwards, R J; Debri, K; Davies, D S; Neubert, D

    1995-10-26

    The induction of cytochrome P450 by enoxacin, ciprofloxacin, and ofloxacin was investigated in female Wistar rats. Animals were treated orally with daily doses ranging from 10 to 400 mg enoxacin per kg body wt, 400 mg ciprofloxacin, or 400 mg ofloxacin per kg body wt for up to 7 days. Activities of methoxyresorufin O-demethylase (MROD) and ethoxyresorufin O-deethylase (EROD) were determined fluorimetrically in hepatic microsomes. MROD activity was increased 2.6-fold after treatment with 100 mg enoxacin per kg body wt for 7 days. Lower doses of enoxacin did not induce MROD activity significantly. Antipeptide antibodies directed specifically against different rat cytochrome P450 enzymes demonstrated that CYP1A2, but not CYP1A1, was induced in rats treated with enoxacin. After ciprofloxacin or ofloxacin treatment, no induction of MROD or EROD activity was observed. Neither ciprofloxacin nor ofloxacin caused any change in CYP1A1 or CYP1A2 apoprotein levels. Further investigations with antipeptide antibodies showed that there was no induction of CYP2B1, CYP2B2, CYP2E1, CYP3A1, CYP3A2, CYP4A1, or CYP4A2 following treatment with enoxacin, ciprofloxacin, or ofloxacin. It is concluded that enoxacin, but not ciprofloxacin or ofloxacin, is an inducer of CYP1A2 in rat liver.

  9. Transfer of benzo[a]pyrene from microplastics to Artemia nauplii and further to zebrafish via a trophic food web experiment: CYP1A induction and visual tracking of persistent organic pollutants.

    PubMed

    Batel, Annika; Linti, Frederic; Scherer, Martina; Erdinger, Lothar; Braunbeck, Thomas

    2016-07-01

    The uptake of microplastic particles and the transfer of potential harmful substances along with microplastics has been studied in a variety of organisms, especially invertebrates. However, the potential accumulation of very small microplastic particles along food webs ending with vertebrate models has not been investigated so far. Therefore, a simple artificial food chain with Artemia sp. nauplii and zebrafish (Danio rerio) was established to analyze the transfer of microplastic particles and associated persistent organic pollutants (POPs) between different trophic levels. Very small (1-20 μm) microplastic particles accumulated in Artemia nauplii and were subsequently transferred to fish. Virgin particles not loaded with POPs did not cause any observable physical harm in the intestinal tracts of zebrafish, although parts of the particles were retained within the mucus of intestinal villi and might even have been taken up by epithelial cells. The transfer of associated POPs was tested with the polycyclic aromatic hydrocarbon benzo[a]pyrene and an ethoxyresorufin-O-deethylase (EROD) assay for CYP1A induction in zebrafish liver as well as via fluorescence analyses. Whereas a significant induction in the EROD assay could not be shown, because of high individual variation and low sensitivity regarding substance concentration, the fluorescence tracking of benzo[a]pyrene indicates that food-borne microplastic-associated POPs may actually desorb in the intestine of fish and are thus transferred to the intestinal epithelium and liver. Environ Toxicol Chem 2016;35:1656-1666. © 2016 SETAC.

  10. A toxic equivalency factor scale for polychlorinated biphenyls (PCBs) in chicken hepatocytes

    SciTech Connect

    Tysklind, M.; Bosveld, A.T.C.; Sinnige, T.; Berg, M. van den

    1995-12-31

    The relative potencies of 20 polychlorinated biphenyls (PCBs) were studied in a chicken embryo hepatocyte system. The 20 congeners were selected according to a full 2{sup 4}-factorial design based on the principal properties of all 154 tetra- through heptachlorinated PCBs. The principal properties were obtained using principal component analysis (PCA) on a multitude of different physico-chemical properties of the PCBs. Toxic equivalency factors (TEFs) were determined for seven out of the twenty PCB congeners, viz. PCB{number_sign}41, PCB{number_sign}60, PCB{number_sign}78, PCB{number_sign}126, PCB{number_sign}169, PCB{number_sign}190, and PCB{number_sign}193, which elicit measurable catalytic ethoxyresorufin-O-deethylase (EROD) activity in the chicken hepatocytes. A multivariate quantitative structure-activity relationship (QSAR) was developed by using partial least-squares to latent variables (PLS) in order to model the relationship between the set of physico-chemical descriptors of the PCBs and their TEF-values. The model showed good correlations between observed and predicted TEF-values for this training set of congeners. From the QSAR, TEF-values were predicted for a large number PCB congeners not yet tested regarding EROD activity in chicken hepatocytes. The predicted TEF-values were validated by TEF-values reported in the literature.

  11. Toxic equivalency factors for tetra- through octachlorinated dibenzofurans in PLHC-1 fish hepatoma cell line

    SciTech Connect

    Tysklind, M.; Rappe, C.; Tillift, D.E.; Eriksson, L.

    1995-12-31

    Planar halogenated hydrocarbons (PHHs) elicit dioxin-like effects in fish at extremely low doses. However, the relative potencies of PHHs in fish differ from mammals in both absolute magnitude and relative rank order. Therefore, the relative potencies of polychlorinated dibenzofurans (PCDFs) were examined in PLHC-1 fish hepatoma cells. The response of PHHs in this cell line correlates with their toxicity to cause early life stage toxicity in fish. Twenty PCDFs were selected by means of a multivariate chemical characterization in combination with a 2{sup 4}-factorial design and separated into a 10 congener training set and 10 congener validation set. Toxic equivalency factors (TEFs) were determined for all 20 PCDF congeners based on ethoxyresorufin-O-deethylase (EROD) induction in the PLHC-1 cells. A quantitative structure-activity relation-ship (QSAR) model was constructed by partial least square modelling (PLS) of the physiochemical descriptor variables for the PCDFs in the training set and their EROD responses in the PLHC-1 cells. A predictive model was developed which accurately assessed the TEFs of the validation set of PCDFs. The model accounted for 87% (R{sup 2}) of the variance in TEFs and a cross-validated variance (Q{sup 2}) of 79%. From this QSAR, TEF values were predicted for all of the tetra through octa-chlorinated PCDFs in fish. Interestingly, there was a high degree of correlation among TEF values calculated in the PLHC-1 cells and the TEF values calculated in H411 E rat hepatoma cells.

  12. Exposure to hydrocarbons 10 years after the Exxon Valdez oil spill: evidence from cytochrome P4501A expression and biliary FACs in nearshore demersal fishes.

    PubMed

    Jewett, Stephen C; Dean, Thomas A; Woodin, Bruce R; Hoberg, Max K; Stegeman, John J

    2002-01-01

    Three biomarkers of hydrocarbon exposure, CYP1A in liver vascular endothelium, liver ethoxyresorufin O-deethylase (EROD), and biliary fluorescent aromatic compounds (FACs), were examined in the nearshore fishes, masked greenling (Hexagrammos octogrammus) and crescent gunnel (Pholis laeta), collected in Prince William Sound, Alaska, 7-10 years after the Exxon Valdez oil spill (EVOS). All biomarkers were elevated in fish collected from sites originally oiled, in comparison to fish from unoiled sites. In 1998, endothelial CYP1A in masked greenling from sites that were heavily oiled in 1989 was significantly higher than in fish collected outside the spill trajectory. In 1999, fishes collected from sites adjacent to intertidal mussel beds containing lingering Exxon Valdez oil had elevated endothelial CYP1A and EROD, and high concentrations of biliary FACs. Fishes from sites near unoiled mussel beds, but within the original spill trajectory, also showed evidence of hydrocarbon exposure, although there were no correlations between sediment petroleum hydrocarbon and any of the biomarkers. Our data show that 10 years after the spill, nearshore fishes within the original spill zone were still exposed to residual EVOS hydrocarbons. PMID:12148943

  13. Semipermeable membrane devices link site-specific contaminants to effects: Part 1 - Induction of CYP1A in rainbow trout from contaminants in Prince William Sound, Alaska.

    PubMed

    Springman, Kathrine R; Short, Jeffrey W; Lindeberg, Mandy R; Maselko, Jacek M; Khan, Colin; Hodson, Peter V; Rice, Stanley D

    2008-12-01

    Extracts from semi-permeable membrane devices (SPMDs) deployed on beaches in Prince William Sound (PWS), Alaska, were used to evaluate if complex contaminant mixtures from different sources can be distinguished by the resulting cytochrome P450 1A (CYP1A) activity in exposed test animals. Deployment sites included canneries, salmon hatcheries, and beaches where lingering oil remains from discharges during the 1964 earthquake or the 1989 Exxon Valdez oil spill. Other sites were selected at random to evaluate region-wide contaminant inputs or were located in salmon streams to evaluate contaminants carried and released by migrating salmon carcasses following reproduction. Following standard deployments of approximately 28 d, an aliquot of the accumulated contaminants was intraperitoneally injected without cleanup into juvenile rainbow trout (Oncorhynchus mykiss). After 2 d and 7 d, the activity of CYP1A was measured by the ethoxyresorufin-o-deethylase (EROD) assay. Exposure to extracts from the oiled sites and one hatchery site with numerous creosote pilings elicited strong EROD responses, whereas fish exposed to salmon stream extracts elicited weak but significant responses during late summer compared to late spring. Responses from the other sites were not significant, indicating contaminants from these sources are unlikely to cause CYP1A induction in resident biota. Rather than simply assessing extant contaminants, this method evaluates the potency of the different sites for bringing about aryl hydrocarbon receptor responses in resident biota. PMID:18845333

  14. Assessment of some innate immune responses in dab (Limanda limanda L.) from the North Sea as part of an integrated biological effects monitoring

    NASA Astrophysics Data System (ADS)

    Skouras, Andreas; Lang, Thomas; Vobach, Michael; Danischewski, Dirk; Wosniok, Werner; Scharsack, Jörn Peter; Steinhagen, Dieter

    2003-10-01

    The marine flatfish dab (Limanda limanda), which lives in direct contact with contaminated sediments, is frequently used as a sentinel species in international monitoring programmes on the biological effects of contaminants. In this study, immune responses were recorded as indicators of sublethal chronic effects of contaminants, in addition to measurement of the induction of mono-oxygenase ethoxyresorufin O-deethylase (EROD) in liver cells, the inhibition of acetylcholin esterase (AChE) in muscle and a quantification of grossly visible diseases and parasites. In total, 336 dab were analysed from five sampling areas in the North Sea, including the German Bight, the Dogger Bank, the Firth of Forth, and two locations close to oil and gas platforms (Ekofisk and Danfield). When considering plasma lysozyme levels, pinocytosis and respiratory burst activity of head kidney leucocytes, a clear gradient could be observed with decreased levels in individuals collected from the Firth of Forth and locations near the oil or gas platforms compared with dab from the Dogger Bank or the German Bight. Individuals with induced EROD activity displayed reduced lysozyme and respiratory burst activities. Lysozyme levels were also reduced in dab with lymphocystis or with nematodes. The data obtained indicate that the assessment of innate immune parameters in a monitoring programme provides supplementary information about immunomodulatory effects associated with the exposure of fish to contaminants. In particular, concentrations of plasma lysozyme, which can be analysed in an easy and inexpensive assay, are considered to be an appropriate parameter for use in a battery of other bioindicators.

  15. Interaction of isosafrole, beta-naphthoflavone and other CYP1A inducers in liver of rainbow trout (Oncorhynchus mykiss) and eelpout (Zoarces viviparus).

    PubMed

    Ronisz, D; Förlin, L

    1998-11-01

    The CYP1A enzyme in liver of rainbow trout (Oncorhynchus mykiss) and eelpout (Zoarces viviparus) was induced by intraperitoneal injections of isosafrole (ISF), beta-naphthoflavone (BNF), retene, 3,3',4,4'-tetrachlorobiphenyl (TCB), Clophen A50 and combinations of these compounds. The livers were sampled 5 days after injection and the microsomal fraction was used to measure the activity of CYP1A (as ethoxyresorufin-O-deethylase (EROD)) and the level of the enzyme (measured semiquantitatively as absorbance using enzyme-linked immunosorbant assay (ELISA)). Induction of CYP1A above the additive effect was observed when ISF was given together with BNF or retene. It was suggested that ISF may stabilize the enzyme or its mRNA or that ISF metabolites inhibit CYP1A processing of BNF and retene, thus increasing the effective doses of these compounds in fish liver. The results indicate a need for further studies of interactions between different CYP1A inducers in fish and a comparison of CYP1A response between different fish species. These results may have implications for the use of CYP1A induction in fish as a biomarker in aquatic systems, since a high EROD activity could be due not only to the presence of one potent inducer, but to synergistic effects of two or more inducers at low concentrations. PMID:9972470

  16. Transfer of benzo[a]pyrene from microplastics to Artemia nauplii and further to zebrafish via a trophic food web experiment: CYP1A induction and visual tracking of persistent organic pollutants.

    PubMed

    Batel, Annika; Linti, Frederic; Scherer, Martina; Erdinger, Lothar; Braunbeck, Thomas

    2016-07-01

    The uptake of microplastic particles and the transfer of potential harmful substances along with microplastics has been studied in a variety of organisms, especially invertebrates. However, the potential accumulation of very small microplastic particles along food webs ending with vertebrate models has not been investigated so far. Therefore, a simple artificial food chain with Artemia sp. nauplii and zebrafish (Danio rerio) was established to analyze the transfer of microplastic particles and associated persistent organic pollutants (POPs) between different trophic levels. Very small (1-20 μm) microplastic particles accumulated in Artemia nauplii and were subsequently transferred to fish. Virgin particles not loaded with POPs did not cause any observable physical harm in the intestinal tracts of zebrafish, although parts of the particles were retained within the mucus of intestinal villi and might even have been taken up by epithelial cells. The transfer of associated POPs was tested with the polycyclic aromatic hydrocarbon benzo[a]pyrene and an ethoxyresorufin-O-deethylase (EROD) assay for CYP1A induction in zebrafish liver as well as via fluorescence analyses. Whereas a significant induction in the EROD assay could not be shown, because of high individual variation and low sensitivity regarding substance concentration, the fluorescence tracking of benzo[a]pyrene indicates that food-borne microplastic-associated POPs may actually desorb in the intestine of fish and are thus transferred to the intestinal epithelium and liver. Environ Toxicol Chem 2016;35:1656-1666. © 2016 SETAC. PMID:26752309

  17. Atrazine promotes biochemical changes and DNA damage in a Neotropical fish species.

    PubMed

    Santos, Thais G; Martinez, Cláudia B R

    2012-11-01

    The effects of Atrazine, an herbicide used worldwide and considered as a potential contaminant in aquatic environments, were assessed on the Neotropical fish Prochilodus lineatus acutely (24 and 48 h) exposed to 2 or 10 μg L(-1) of atrazine by using a set of biochemical and genetic biomarkers. The following parameters were measured in the liver: activity of the biotransformation enzymes ethoxyresorufin-O-deethylase (EROD) and glutathione S transferase (GST), antioxidant enzymes superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR), content of reduced glutathione (GSH), generation of reactive oxygen species (ROS) and occurrence of lipid peroxidation (LPO); in brain and muscle the activity of acetylcholinesterase (AChE) and DNA damage (comet assay) on erythrocytes, gills and liver cells. A general decreasing trend on the biotransformation and antioxidant enzymes was observed in the liver of P. lineatus exposed to atrazine; except for GR, all the other antioxidant enzymes (SOD, CAT and GPx) and biotransformation enzymes (EROD and GST) showed inhibited activity. Changes in muscle or brain AChE were not detected. DNA damage was observed in the different cell types of fish exposed to the herbicide, and it was probably not from oxidative origin, since no increase in ROS generation and LPO was detected in the liver. These results show that atrazine behaves as enzyme inhibitor, impairing hepatic metabolism, and produces genotoxic damage to different cell types of P. lineatus.

  18. Effects of water accommodated fractions of crude oils and diesel on a suite of biomarkers in Atlantic cod (Gadus morhua).

    PubMed

    Holth, T F; Eidsvoll, D P; Farmen, E; Sanders, M B; Martínez-Gómez, C; Budzinski, H; Burgeot, T; Guilhermino, L; Hylland, K

    2014-09-01

    The aim of this study was to characterize concentration- and time-dependent responses in juvenile Atlantic cod (Gadus morhua) following exposure for one and three weeks to the water-soluble fraction (WAF) of three weathered oils: Arabian Light crude oil (ALC), North Sea crude oil (NSC) and ship-diesel. The sum of polycyclic aromatic hydrocarbons (PAH) in water was highest after one week of exposure and within environmentally relevant concentrations. PAH metabolites in bile confirmed exposure to and uptake of PAHs. Hepatic cytochrome P450 1A (CYP1A) gene expression (mRNA quantification) increased dramatically following exposure to all three oil types (fold-change up to 165) and there was a time lag between gene and protein expression. Hepatic CYP1A protein concentration and ethoxyresorufin-O-deethylase (EROD) activity were more variable among individuals and treatments than gene expression. EROD activity in liver and gills increased in fish exposed to WAF from the two crude oils, but not in fish exposed to WAF from diesel. Exposure to diesel appeared to induce oxidative stress to a greater extent than exposure to crude oils. Other biomarkers (glutathione S-transferases, acetylcholine esterase, vitellogenin) did not appear to respond to the exposure and hence did not discriminate among oils. Biomarker responses in cod after exposure to weathered crude oils and diesel suggested that the CYP1A system and oxidative stress markers have the highest potential for discriminating among different oil types and to monitor the environmental consequences of spills.

  19. Comparative study of 17 β-estradiol on endocrine disruption and biotransformation in fingerlings and juveniles of Japanese sea bass Lateolabrax japonicus.

    PubMed

    Thilagam, Harikrishnan; Gopalakrishnan, Singaram; Bo, Jun; Wang, Ke-Jian

    2014-08-30

    Estrogenic contaminants in the aquatic environment are associated with endocrine disruption and feminization in fish. The effects of endocrine disrupting chemicals (EDCs) on fish have been well documented. However, very few studies have focused on 17 β-estradiol (E2) and its effects on endocrine system and biotransformation in a single prolonged exposure. This study investigated changes in the levels of serotonin (5-hydroxytryptamine) and acetyl choline esterase (AchE) in brain, cortisol in plasma and Ethoxyresorufin-O-deethylase (EROD) activity in gill of two different size groups (fingerlings and juveniles) of Japanese sea bass (Lateolabrax japonicus) upon exposure to two sub-lethal concentrations (200 and 2000 ng L(-1)) of E2 for 30 d. The results indicate that cortisol level and EROD activity significantly increased in both groups, whereas serotonin level increased in juveniles and decreased in fingerlings due to E2 exposure. The correlation analysis revealed that E2 significantly affected the endocrine and biotransformation systems in both age groups.

  20. Biomarker sensitivity for polynuclear and halogenated aromatic hydrocarbon contamination in fish species from Galveston Bay

    SciTech Connect

    Willett, K.; McDonald, S.; Steinberg, M.; Beatty, K.; Safe, S.

    1995-12-31

    The Galveston Bay estuary exhibits a contamination gradient for polynuclear aromatic hydrocarbons (PAHs) and halogenated aromatic hydrocarbons, which is useful for comparing biomarker response sensitivity in fish taken from different bay locations. Two fish species, hardhead catfish (Arius felis) and Atlantic croaker (Micropogon undulatus), were collected from four stations where sediment total PAHs ranged from 68 to > 1,000 ng/g. Hardhead catfish showed no consistent CYP1A mediated responses (hepatic ethoxyresorufin-O-deethylase activity (EROD), CYP1A mRNA levels, or CYP1A immunoreactive protein) in the field collected fish or in fish dosed with up to 15 mg/kg benzo(a)pyrene (BaP). Significant differences were seen in field collected hardhead catfish in biliary concentrations of naphthalene, phenanthrene, and BaP metabolites. Conversely, in croakers taken from the same four Galveston Bay locations, there were significant elevations IN EROD and glutathione-S-transferase activities, CYP1A immunoreactive protein, and biliary PAH metabolites at the contaminated stations. These studies suggest that croaker is a good monitoring species especially with respect to induction of CYP1A mediated responses by PAHs. Biliary PAH metabolites and PAH-DNA adducts were sensitive to PAH contamination in both species.