Correlation of antimutagenic activity and suppression of CYP1A with the lipophilicity of alkyl gallates and other phenolic compounds.

PubMed

Feng, Qing; Kumagai, Takeshi; Nakamura, Yoshimasa; Uchida, Koji; Osawa, Toshihiko

2003-05-09

Alkyl gallates are widely used as food antioxidants. Methyl, ethyl, propyl, lauryl, and cetyl gallates showed antimutagenicity to activated 2-aminoanthracene (2AA)-induced SOS responses in Salmonella typhimurium TA1535/pSK1002. They also exhibited a suppressive effect on 3-methylcholanthrene (3-MC)-induced cytochrome P450 1A (CYP1A) in human hepatoma HepG2 cells, as indexed by the 7-ethoxyresorufin-O-deethylase (EROD) activity, and on CYP1A protein level. Both antimutagenicity and suppression of CYP1A appeared to be dependent on alkyl chain lengths, which suggested lipophilicity dependence. Based on those results, we investigated 26 other phenolic compounds for their lipophilicity, antimutagenicity and inhibition of EROD activity. The lipophilicity correlated well with the inhibition of EROD activity (r=0.78), and the inhibition of EROD activity correlated with the antimutagenicity of those compounds (r=0.71). The results suggest that the lipophilicity of the phenolic compounds may be an important factor in their ability to inhibit EROD activity.

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.

Maternal drug abuse and human term placental xenobiotic and steroid metabolizing enzymes in vitro.

PubMed

Paakki, P; Stockmann, H; Kantola, M; Wagner, P; Lauper, U; Huch, R; Elovaara, E; Kirkinen, P; Pasanen, M

2000-02-01

We evaluated the impact of maternal drug abuse at term on human placental cytochrome P450 (CYP)-mediated (Phase I) xenobiotic and steroid-metabolizing activities [aromatase, 7-ethoxyresorufin O-deethylase (EROD), 7-ethoxycoumarin O-deethylase (ECOD), pyrene 1-hydroxylase (P1OH), and testosterone hydroxylase], and androstenedione-forming isomerase, NADPH quinone oxidoreductase (Phase II), UDP-glucuronosyltransferase (UGT), and glutathione S-transferase (GST) activities in vitro. Overall, the formation of androstenedione, P1OH, and testosterone hydroxylase was statistically significant between control and drug-abusing subjects; we observed no significant differences in any other of the phase I and II activities. In placentas from drug-abusing mothers, we found significant correlations between ECOD and P1OH activities (p < 0. 001), but not between ECOD and aromatase or P1OH and EROD activities; we also found significant correlations between blood cotinine and UGT activities (p < 0.01). In contrast, in controls (mothers who did not abuse drugs but did smoke cigarettes), the P1OH activity correlated with ECOD, EROD (p < 0.001), and testosterone hydroxylase (p < 0.001) activities. Our results (wider variation in ECOD activity among tissue from drug-abusing mothers and the significant correlation between P1OH and ECOD activities, but not with aromatase or EROD activities) indicate that maternal drug abuse results in an additive effect in enhancing placental xenobiotic metabolizing enzymes when the mother also smokes cigarettes; this may be due to enhancing a "silent" CYP form, or a new placental CYP form may be activated. The change in the steroid metabolism profile in vitro suggests that maternal drug abuse may alter normal hormonal homeostasis during pregnancy.

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

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.

E2 potentializes benzo(a)pyrene-induced hepatic cytochrome P450 enzyme activities in Nile tilapia at high concentrations.

PubMed

Rodrigues, Aline Cristina Ferreira; Moneró, Tatiana de Oliveira; Frighetto, Rosa Toyoko Shiraishi; de Almeida, Eduardo Alves

2015-11-01

In the aquatic environment, biotransformation enzymes are established biomarkers for assessing PAH exposure in fish, but little is known about the effect of 17β-estradiol (E2) on these enzymes during exposure to benzo(a)pyrene (BaP). In this study, Nile tilapia (Oreochromis niloticus) were exposed for 3, 5, and 10 days to BaP (300 μg L(-1)) and E2 (5 μg L(-1)). These substances were applied isolated or mixed. In the mixture experiment, fish were analyzed pre- and postexposure in order to better understand whether preexposure to the hormone masks the responses activated by PAH or vice versa. Phase I enzymes ethoxyresorufin-O-deethylase (EROD), pentoxyresorufin-O-depenthylase (PROD), and benzyloxyresorufin-O-debenzylase (BROD) activities as well as the phase II enzyme glutathione S-transferase (GST) were analyzed. Isolated E2 treatment decreased EROD activity after 3 days, but this enzyme activity returned to control values after 5 and 10 days of exposure. Isolated BaP treatment significantly induced EROD activity after 3 and 5 days, and the activity returned to control levels after ten exposure days. Combined treatment (E2 + Bap) significantly increased EROD activity, both in the pre- and postexposure. This increase was even higher than in the isolated BaP treatment, suggesting a synergism between these two compounds. When E2 and BaP were used singly, they did not change BROD and PROD activities. However, combined treatment (E2 + Bap) significantly increased PROD activity. Isolated BaP treatment increased GST activity after 10 days. However, this response was not observed in the mixture treatment, suggesting that E2 suppressed the GST induction modulated by BaP. The results put together indicated that E2 altered the biotransformation pathway regarding enzymes activated by BaP in Nile tilapia.

[Effect of bemethyl on cytochrome P-450-dependent monoxygenases in the human liver and lymphocytes].

PubMed

Sorokina, E A; Sibiriak, S V; Sergeeva, S A

2002-01-01

Effects of the actoprotector bemithyl (50 mg/kg, p.o.) upon a single or five-fold administration on the cytochrome P-450 and b5 content and the isoform-specific and nonspecific monooxygenase activity [aminopyrine-N-demethylase, aniline-p-hydroxylase, 4-nitroanisole-o-demethylase,2,5-diphenyloxazole-p-hydroxylase, 7-ethoxyresorufin-o-deethylase (EROD), benzyloxyresorufin-o-debenzylase (BROD)] in rat liver were evaluated. In addition, the influence of bemithyl (0.(1)-100 microM) on the development of EROD and BROD activity was studied on the mitogen-stimulated human lymphocytes in vitro. Administered in rats, bemithyl exhibited the properties of a cytochrome P-450 inductor of the mixed type, which was manifested by an increase in the total cytochrome P-450 content in liver microsomes and in the monooxygenase activity related to both Ah-receptor-dependent and -independent isoforms (except for the aniline-p-hydroxylase activity). The induction of the monooxygenase activity realized by Ah-receptor-dependent isoforms (4-nitroanisole-o-demethylase, 2,5-diphenyloxazole-p-hydroxylase, and EROD activity) was more pronounced, reaching maximum upon a single drug administration. Acting upon the human lymphocytes in vitro, high concentrations of bemithyl increased expression of the EROD activity, while low drug concentrations stimulated the BROD activity.

The effect of alloxan diabetes on the activity of some mixed function oxidases in male rats.

PubMed

Nedjar, A; Stoytchev, T

1990-01-01

The effect of alloxan-induced diabetes on the duration of hexobarbital sleep (HB sleep) the activity of ethylmorphine-N-demethylase (EMND), aniline hydroxylase (AH), the content of microsomal cytochrome P-450 and b5, on the activity of ethoxycumarine-0-deethylase (ECOD) and ethoxyresorufine-0-deethylase (EROD) after induction with beta naphthoflavone (beta-NF), as well as the activity of benzphetamine-N-demethylase and pentoxyresorufine-O-dealkylase (PROD) after induction with phenobarbital (PB), was studied in experiments on male Wistar rats. In rats with alloxan diabetes there was a significant prolongation of HB sleep (by 106%) and inhibition of the liver EMND (by 54%), while the AH activity increased by 131%, with a parallel rise in the content of microsomal cytochromes P-450 (by 67%) and b5 (by 113%). In rats with alloxan diabetes the enzyme-inducing effect of beta-NF with respect to the activities of EROD and ECOD is reduced, although diabetes by itself causes a rise in the ECOD activity in untreated animals. When induced with PB, the PROD and benzphetamine-N-demethylase activity in diabetic rats is lower than in the healthy animals. However, if the enzyme activity after the application of inducers is referred to the respective starting enzyme activities of the two groups of animals, it is found that the enzyme-inducing effect of PB is preserved and even slightly potentiated in the diabetic rats compared with the healthy ones: the increases in the benzphetamine-N-demethylase activity is by 60% in the diabetic rats, compared with a rise of 28% in the healthy animals, of the PROD activity 19 times for the diabetic compared with 16 times increase for the healthy rats.

CYP1A protein expression and catalytic activity in double-crested cormorants experimentally exposed to Deepwater Horizon Mississippi Canyon 252 oil

USGS Publications Warehouse

Alexander, Courtney R.; Hooper, Michael J.; Cacela, Dave; Smelker, Kim D.; Calvin, Caleshia S.; Dean, Karen M.; Bursian, Steve J.; Cunningham, Fred L.; Hanson-Dorr, Katie C.; Horak, Katherine E.; Isanhart, John P.; Link, Jane E.; Shriner, Susan A.; Godard-Codding, Céline A.J.

2017-01-01

Double-crested cormorants (Phalacrocorax auritus, DCCO) were orally exposed to Deepwater Horizon Mississippi Canyon 252 (DWH) oil to investigate oil-induced toxicological impacts. Livers were collected for multiple analyses including cytochrome P4501A (CYP1A) enzymatic activity and protein expression. CYP1A enzymatic activity was measured by alkoxyresorufin O-dealkylase (AROD) assays. Activities specific to the O-dealkylation of four resorufin ethers are reported: benzyloxyresorufin O-debenzylase (BROD), ethoxyresorufin O-deethylase (EROD), methoxyresorufin O-demethylase (MROD), and pentoxyresorufin O-depentylase (PROD). CYP1A protein expression was measured by western blot analysis with a CYP1A1 mouse monoclonal antibody. In study 1, hepatic BROD, EROD, and PROD activities were significantly induced in DCCO orally exposed to 20 ml/kg body weight (bw) oil as a single dose or daily for 5 days. Western blot analysis revealed hepatic CYP1A protein induction in both treatment groups. In study 2 (5 ml/kg bw oil or 10 ml/kg bw oil, 21 day exposure), all four hepatic ARODs were significantly induced. Western blots showed an increase in hepatic CYP1A expression in both treatment groups with a significant induction in birds exposed to 10 ml/kg oil. Significant correlations were detected among all 4 AROD activities in both studies and between CYP1A protein expression and both MROD and PROD activities in study 2. EROD activity was highest for both treatment groups in both studies while BROD activity had the greatest fold-induction. While PROD activity values were consistently low, the fold-induction was high, usually 2nd highest to BROD activity. The observed induced AROD profiles detected in the present studies suggest both CYP1A4/1A5 DCCO isoforms are being induced after MC252 oil ingestion. A review of the literature on avian CYP1A AROD activity levels and protein expression after exposure to CYP1A inducers highlights the need for species-specific studies to

Low-temperature thermal decomposition of dioxin-like compounds in fly ash: combination of chemical analysis with in vitro bioassays (EROD and DR-CALUX).

PubMed

Behnisch, Peter A; Hosoe, Kazunori; Shiozaki, Ken; Ozaki, Hironori; Nakamura, Kazuo; Sakai, Shin-Ichi

2002-12-01

To investigate the dechlorination of fly ash during low-temperature treatment under oxygen-deficient conditions (thermocatalyic treatment or Hagenmaier process), six fly ash samples from six different incineration plants were treated in a laboratory experiment or in the actual plant, either under ideal (400 degrees C, 120 min) or intermediate (300 degrees C, 30 min) conditions. The aim of the present study was to confirm the decrease in the I-TEQ (international toxicity equivalency) of polychlorinated dibenzo-p-dioxins/-furans (PCDD/Fs) and coplanar polychlorinated biphenyls (co-PXBs) and, also for the first time, the decrease in the sum of dioxin-like toxicity (bioassay- or bio-TEQ) of all kinds of other dioxin-like Ah receptor agonists (such as PXDD/Fs, PXBs, PXN, X = Br, F) measured by two state-of-the-art cell-based Ah receptor-dependent bioassays: H4IIE-Ethoxy-Resorufin-o-Deethylase (EROD) and H4IIE-luc/DR-Chemical Activated Luciferase expression (DR-CALUX). The treatment efficiency was calculated on the basis of the reduction in the I-TEQ and bio-TED values. For these fly ash samples, the treatment efficiency, as measured by chemical analysis, was higher than 99%, and 85%-99%, in the case of the bio-TED values, indicating that these Ah receptor binding toxic compounds were sufficiently decomposed. Bio-TEQ values for untreated fly ash samples (n = 6) were on average 1.2 times (range 0.7-1.9), for the H4IIE-EROD assay, and 2.8 times (1.1-4.9), for the DR-CALUX assay, higher than I-TEQ values measured by chemical analyses (sum of PCDD/Fs and co-PCBs). In the case of these fly ash samples treated under ideal conditions and therefore low in contaminants, the bio-TEQ values were on average 1.4 times (range 0.9-1.8), for the H4IIE-EROD assay, and 5.1 times (range 1.2-12), for the DR-CALUX assay, higher than the I-TEQ values.

Induction of EROD and BFCOD activities in tissues of barbel (Barbus callensis) from a water reservoir in Algeria.

PubMed

Habila, Safia; Leghouchi, Essaid; Valdehita, Ana; Bermejo-Nogales, Azucena; Khelili, Smail; Navas, José M

2017-08-01

EROD and BFCOD activities were measured in liver and gills of barbel (Barbus callensis, a native North African species) captured at Beni Haroun lake, the most important water reservoir in Algeria. This lake receives wastewater from different origins. Thus, we assessed the level of pollution through the induction of detoxification activities in tissues of barbel, evaluating simultaneously the suitability of this species to be used as a sentinel. Fish were collected between March 2015 and January 2016 at three locations taking into account the pollution sources and accessibility. In liver, EROD and BFCOD showed the highest induction in October specially in the location of the dam that received pollutants. In gills, only EROD, but not BFCOD, activity was detected. Maximal EROD induction was noted in samples from January. Fish cell lines (RTG-2 and PLHC-1) were exposed to sediments extracts collected at Beni Haroun lake and enzyme activities (EROD and BFCOD, respectively) were measured. Sediment extracts did not induce BFCOD activity. The EROD induction observed in RTG-2 cells was in line with the results observed in fish tissues. Our results suggest that the lake is at risk from pollution and that Barbus callensis is a good sentinel species. Copyright © 2017 Elsevier Inc. All rights reserved.

Multibiomarker responses in fish from the Moselle River (France).

PubMed

Flammarion, P; Devaux, A; Nehls, S; Migeon, B; Noury, P; Garric, J

2002-02-01

The response of wild fish to pollutants was studied using two biomarkers in chub (Leuciscus cephalus) at five stations in the Moselle River (France) in 1998 and in 1999. The induction of cytochrome P450 1A was quantified by the ethoxyresorufin O-deethylase (EROD) activity in the liver and the level of DNA single-strand breaks was determined in erythrocytes using the comet assay. EROD activity was observed to be up to 10-fold induced in both males and females from the downstream stations in comparison to the fish from the upstream station. Levels of DNA damage did not parallel EROD induction. Chemical analyses did not clearly explain the responses of the studied biomarkers, confirming the great difficulty in relating chemical and biological information in the field. This study confirms the difficulty in assessing the biological effects of mixtures of pollutants and points out the usefulness of a large array of biomarkers.

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.

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

Aryl hydrocarbon receptor-mediated activity of particulate organic matter from the Paso del Norte airshed along the U.S.-Mexico border.

PubMed Central

Arrieta, Daniel E; Ontiveros, Cynthia C; Li, Wen-Whai; Garcia, Jose H; Denison, Michael S; McDonald, Jacob D; Burchiel, Scott W; Washburn, Barbara Shayne

2003-01-01

In this study, we determined the biologic activity of dichloromethane-extracted particulate matter < 10 micro m in aerodynamic diameter (PM10) obtained from filters at three sites in the Paso del Norte airshed, which includes El Paso, Texas, USA; Juarez, Chihuahua, Mexico, and Sunland Park, New Mexico, USA. The extracts were rich in polycyclic aromatic hydrocarbons (PAHs) and had significant biologic activity, measured using two in vitro assay systems: ethoxyresorufin-(O-deethylase (EROD) induction and the aryl hydrocarbon-receptor luciferase reporter system. In most cases, both EROD (5.25 pmol/min/mg protein) and luciferase activities (994 relative light units/mg) were highest in extracts from the Advance site located in an industrial neighborhood in Juarez. These values represented 58% and 55%, respectively, of induction associated with 1 micro M ss-naphthoflavone exposures. In contrast, little activity was observed at the Northeast Clinic site in El Paso, the reference site. In most cases, luciferase and EROD activity from extracts collected from the Tillman Health Center site, situated in downtown El Paso, fell between those observed at the other two sites. Overall, a statistically significant correlation existed between PM10 and EROD and luciferase activities. Chemical analysis of extracts collected from the Advance site demonstrated that concentrations of most PAHs were higher than those reported in most other metropolitan areas in the United States. Calculations made with these data suggest a cancer risk of 5-12 cases per 100,000 people. This risk estimate, as well as comparisons with the work of other investigators, raises concern regarding the potential for adverse health effects to the residents of this airshed. Further work is needed to understand the sources, exposure, and effects of PM10 and particulate organic material in the Paso del Norte airshed. PMID:12896850

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. Copyright © 2016 Elsevier Inc. All rights reserved.

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

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

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,more » 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.« less

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

In vitro interactions of malachite green and leucomalachite green with hepatic drug-metabolizing enzyme systems in the rainbow trout (Onchorhyncus mykiss).

PubMed

Nebbia, Carlo; Girolami, Flavia; Carletti, Monica; Gasco, Laura; Zoccarato, Ivo; Giuliano Albo, Alessandra

2017-10-05

Malachite green (MG) has been widely used in aquaculture to treat a number of microbial and parasitic diseases. It is currently banned in the EU because of the high cytotoxicity and carcinogenic activity, which is also shared by leucomalachite green (LMG), a reduced MG metabolite that can persist in fish tissues for months. There is scant information about the ability of either compound to interact with drug metabolizing enzymes in fish. Therefore we evaluated the in vitro effects of MG and LMG (25, 50 and 100μM) on some DMEs and glutathione (GSH) content in rainbow trout liver subfractions. LMG did not affect any of the examined parameters. In contrast, MG proved to deplete GSH and to depress to a various extent the activities of NAD(P)H cytochrome c reductase, 7-ethoxycoumarin O-deethylase, 1-naphthol uridindiphosphoglucuronyl-transferase and maximally those of 7-ethoxyresorufin O-deethylase (EROD) and glutathione S-transferase (GST) accepting 1-chloro2,4-dinitrobenzene (CDNB) as substrate. The inhibition mechanisms of EROD and GST were investigated by means of non-linear Michaelis-Menten kinetics and Lineweaver-Burk plots using 0.175-8μM MG. The calculated IC 50 for EROD was 7.1μM, and the inhibition appeared to be competitive (K i 2.78±0.24μM). In the case of GST, the calculated IC 50 was 0.53μM. The inhibition was best described as competitive toward GSH (Ki 0.39±0.02μM) and of mixed-type toward CDNB (Ki 0.64±0.06μM). Our findings indicate that, contrary to LMG, MG behaves as a relatively strong inhibitor of certain liver DMEs and can reversibly bind GSH. Copyright © 2017 Elsevier B.V. All rights reserved.

Effects of Sublethal Exposure to a Glyphosate-Based Herbicide Formulation on Metabolic Activities of Different Xenobiotic-Metabolizing Enzymes in Rats.

PubMed

Larsen, Karen; Najle, Roberto; Lifschitz, Adrián; Maté, María L; Lanusse, Carlos; Virkel, Guillermo L

2014-07-01

The activities of different xenobiotic-metabolizing enzymes in liver subcellular fractions from Wistar rats exposed to a glyphosate (GLP)-based herbicide (Roundup full II) were evaluated in this work. Exposure to the herbicide triggered protective mechanisms against oxidative stress (increased glutathione peroxidase activity and total glutathione levels). Liver microsomes from both male and female rats exposed to the herbicide had lower (45%-54%, P < 0.01) hepatic cytochrome P450 (CYP) levels compared to their respective control animals. In female rats, the hepatic 7-ethoxycoumarin O-deethylase (a general CYP-dependent enzyme activity) was 57% higher (P < 0.05) in herbicide-exposed compared to control animals. Conversely, this enzyme activity was 58% lower (P < 0.05) in male rats receiving the herbicide. Lower (P < 0.05) 7-ethoxyresorufin O-deethlyase (EROD, CYP1A1/2 dependent) and oleandomycin triacetate (TAO) N-demethylase (CYP3A dependent) enzyme activities were observed in liver microsomes from exposed male rats. Conversely, in females receiving the herbicide, EROD increased (123%-168%, P < 0.05), whereas TAO N-demethylase did not change. A higher (158%-179%, P < 0.01) benzyloxyresorufin O-debenzylase (a CYP2B-dependent enzyme activity) activity was only observed in herbicide-exposed female rats. In herbicide-exposed rats, the hepatic S-oxidation of methimazole (flavin monooxygenase dependent) was 49% to 62% lower (P < 0.001), whereas the carbonyl reduction of menadione (a cytosolic carbonyl reductase-dependent activity) was higher (P < 0.05). Exposure to the herbicide had no effects on enzymatic activities dependent on carboxylesterases, glutathione transferases, and uridinediphospho-glucuronosyltransferases. This research demonstrated certain biochemical modifications after exposure to a GLP-based herbicide. Such modifications may affect the metabolic fate of different endobiotic and xenobiotic substances. The pharmacotoxicological significance of these

Effects of chronic exposure to tributyltin on tissue-specific cytochrome P450 1 regulation in juvenile common carp.

PubMed

Li, Zhi-Hua; Zhong, Li-Qiao; Mu, Wei-Na; Wu, Yan-Hua

2016-01-01

1. The purpose of this study was to compare tributyltin (TBT)-induced cytochrome P450 1 (CYP450 1) regulation in liver, gills and muscle of juvenile common carp (Cyprinus carpio). 2. Fish were exposed to sublethal concentrations of TBT (75, 0.75 and 7.5 μg/L) for 60 days. CYP450 1A was measured at the enzyme activity level as 7-ethoxyresorufin-O-deethylase (EROD) activity, as well as the mRNA expression of CYP450 1 family genes (CYP1A, CYP1B, CYP1C1 and CYP1C2) in fish tissues. 3. Based on the results, the liver displayed the highest absolute levels of EROD activity, both under nonexposed and exposed conditions. Additional, EROD activities and CYP1A gene levels showed a good correlation in all three organs. According to the mRNA expression of CYP450 1 family genes, it suggested that CYP1A was to accommodate most EROD activity in fish, but other CYP450 forms also involved in this proceeding. 4. Overall, the study revealed both similarities and differences in the concentration-dependent CYP450 1 responses of the three target organs, which could provide useful information to better understand the mechanisms of TBT-induced bio-toxicity.

Effect of benzo[a]pyrene on detoxification and the activity of antioxidant enzymes of marine microalgae

NASA Astrophysics Data System (ADS)

Shen, Chen; Miao, Jingjing; Li, Yun; Pan, Luqing

2016-04-01

The objective of this study was to examine the effect of benzo[a]pyrene (BaP) on the detoxification and antioxidant systems of two microalgae, Isochrysis zhanjiangensis and Platymonas subcordiformis. In our study, these two algae were exposed to BaP for 4 days at three different concentrations including 0.5 μg L-1 (low), 3 μg L-1 (mid) and 18 μg L-1 (high). The activity of detoxification enzymes, ethoxyresorufin O-deethylase (EROD) and glutathione S-transferase (GST) increased in P. subcordiformis in all BaP-treated groups. In I. zhanjiangensis, the activity of these two enzymes increased at the beginning of exposure, and then decreased in the groups treated with mid- and high BaP. The activity of antioxidant enzyme superoxide dismutase (SOD) increased in I. zhanjiangensis in all BaP-treated groups, and then decreased in high BaP-treated group, while no significant change was observed in P. subcordiformis. The activity of antioxidant enzyme catalase (CAT) increased in I. zhanjiangensis and P. subcordiformis in all BaPtreated groups. The content of malondialdehyde (MDA) in Isochrysis zhanjiangensis increased first, and then decreased in high BaP-treated group, while no change occurred in P. subcordiformis. These results demonstrated that BaP significantly influenced the activity of detoxifying and antioxidant enzymes in microalgae. The metabolic related enzymes (EROD, GST and CAT) may serve as sensitive biomarkers of measuring the contamination level of BaP in marine water.

Use of octopus as a bioindicator species: Baseline studies

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

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

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 valuesmore » 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.« less

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

PubMed

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

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.

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

Chemoprotective potentials of homoisoflavonoids and chalcones of Dracaena cinnabari: modulations of drug-metabolizing enzymes and antioxidant activity.

PubMed

Machala, M; Kubínová, R; Horavová, P; Suchý, V

2001-03-01

A series of homoisoflavonoids and chalcones, isolated from the endemic tropical plant Dracaena cinnabari Balf. (Agavaceae), were tested for their potential to inhibit cytochrome P4501A (CYP1A) enzymes and Fe-enhanced in vitro peroxidation of microsomal lipids in C57B1/6 mouse liver. The effects of the polyphenolic compounds were compared with those of prototypal flavonoid modulators of CYP1A and the well-known antioxidant, butylated hydroxytoluene. 2-Hydroxychalcone and partly 4,6-dihydroxychalcone were found to be strong inhibitors of CYP1A-dependent 7-ethoxyresorufin O-deethylase (EROD) activity in vitro comparable to the effects of quercetin and chrysin. The first screening of flavonoids and chalcones of Dracaena cinnabari for antioxidant activity was done in an in vitro microsomal peroxidation assay. While chalcones were shown to be poor antioxidants, 7,8-methylenedioxy-3(4-hydroxybenzyl) chromane, as one of the tested homoisoflavonoids, exhibited a strong antioxidant activity comparable to that of the strongest flavonol antioxidant, quercetin. Copyright 2001 John Wiley & Sons, Ltd.

Membrane Phospholipid Augments Cytochrome P4501a Enzymatic Activity by Modulating Structural Conformation during Detoxification of Xenobiotics

PubMed Central

Ghosh, Manik C.; Ray, Arun K.

2013-01-01

Cytochrome P450 is a superfamily of membrane-bound hemoprotein that gets involved with the degradation of xenobiotics and internal metabolites. Accumulated body of evidence indicates that phospholipids play a crucial role in determining the enzymatic activity of cytochrome P450 in the microenvironment by modulating its structure during detoxification; however, the structure-function relationship of cytochrome P4501A, a family of enzymes responsible for degrading lipophilic aromatic hydrocarbons, is still not well defined. Inducibility of cytochrome P4501A in cultured catfish hepatocytes in response to carbofuran, a widely used pesticide around the world, was studied earlier in our laboratory. In this present investigation, we observed that treating catfish with carbofuran augmented total phospholipid in the liver. We examined the role of phospholipid on the of cytochrome P4501A-marker enzyme which is known as ethoxyresorufin-O-deethylase (EROD) in the context of structure and function. We purified the carbofuran-induced cytochrome P4501A protein from catfish liver. Subsequently, we examined the enzymatic activity of purified P4501A protein in the presence of phospholipid, and studied how the structure of purified protein was influenced in the phospholipid environment. Membrane phospholipid appeared to accelerate the enzymatic activity of EROD by changing its structural conformation and thus controlling the detoxification of xenobiotics. Our study revealed the missing link of how the cytochrome P450 restores its enzymatic activity by changing its structural conformation in the phospholipid microenvironment. PMID:23469105

Membrane phospholipid augments cytochrome P4501a enzymatic activity by modulating structural conformation during detoxification of xenobiotics.

PubMed

Ghosh, Manik C; Ray, Arun K

2013-01-01

Cytochrome P450 is a superfamily of membrane-bound hemoprotein that gets involved with the degradation of xenobiotics and internal metabolites. Accumulated body of evidence indicates that phospholipids play a crucial role in determining the enzymatic activity of cytochrome P450 in the microenvironment by modulating its structure during detoxification; however, the structure-function relationship of cytochrome P4501A, a family of enzymes responsible for degrading lipophilic aromatic hydrocarbons, is still not well defined. Inducibility of cytochrome P4501A in cultured catfish hepatocytes in response to carbofuran, a widely used pesticide around the world, was studied earlier in our laboratory. In this present investigation, we observed that treating catfish with carbofuran augmented total phospholipid in the liver. We examined the role of phospholipid on the of cytochrome P4501A-marker enzyme which is known as ethoxyresorufin-O-deethylase (EROD) in the context of structure and function. We purified the carbofuran-induced cytochrome P4501A protein from catfish liver. Subsequently, we examined the enzymatic activity of purified P4501A protein in the presence of phospholipid, and studied how the structure of purified protein was influenced in the phospholipid environment. Membrane phospholipid appeared to accelerate the enzymatic activity of EROD by changing its structural conformation and thus controlling the detoxification of xenobiotics. Our study revealed the missing link of how the cytochrome P450 restores its enzymatic activity by changing its structural conformation in the phospholipid microenvironment.

A multi-year study of hepatic biomarkers in coastal fishes from the Gulf of Mexico after the Deepwater Horizon Oil Spill.

PubMed

Smeltz, Marci; Rowland-Faux, Laura; Ghiran, Céline; Patterson, William F; Garner, Steven B; Beers, Alan; Mièvre, Quentin; Kane, Andrew S; James, Margaret O

2017-08-01

Following the 2010 Gulf of Mexico oil spill, concerns were raised regarding exposure of fish to crude oil components, particularly polycyclic aromatic hydrocarbons (PAHs). This three year study examined hepatic enzymes in post-mitochondrial supernatant fractions from red snapper (Lutjanus campechanus) and gray triggerfish (Balistes capriscus) collected in the north central Gulf of Mexico between 2011 and 2014. Biomarker activities evaluated included benzo(a)pyrene hydroxylase (AHH), ethoxyresorufin O-deethylase (EROD), glutathione transferase (GST), and glutathione peroxidase (GPx). Mean EROD activity was higher in gray triggerfish (12.97 ± 7.15 pmol/min/mg protein [mean ± SD], n = 115) than red snapper (2.75 ± 1.92 pmol/min/mg protein, n = 194), p < 0.0001. In both species, EROD declined over time between 2011 and 2014. Declines in GST and GPx activities were also noted over this time period for both species. Gray triggerfish liver was fatty, and heptane extracts of the liver fat contained fluorescent substances with properties similar to known PAHs, however the origin of these PAHs is unknown. Copyright © 2017 Elsevier Ltd. All rights reserved.

Effects of frying oil and Houttuynia cordata thunb on xenobiotic-metabolizing enzyme system of rodents

PubMed Central

Chen, Ya-Yen; Chen, Chiao-Ming; Chao, Pi-Yu; Chang, Tsan-Ju; Liu, Jen-Fang

2005-01-01

AIM: To evaluate the effects of frying oil and Houttuynia cordata Thunb (H. cordata), a vegetable traditionally consumed in Taiwan, on the xenobiotic-metabolizing enzyme system of rodents. METHODS: Forty-eight Sprague-Dawley rats were fed with a diet containing 0%, 2% or 5% H. cordata powder and 15% fresh soybean oil or 24-h oxidized frying oil (OFO) for 28 d respectively. The level of microsomal protein, total cytochrome 450 content (CYP450) and enzyme activities including NADPH reductase, ethoxyresorufin O-deethylase (EROD), pentoxyresorufin O-dealkylase (PROD), aniline hydroxylase (ANH), aminopyrine demethylase (AMD), and quinone reductase (QR) were determined. QR represented phase II enzymes, the rest of the enzymes tested represented phase I enzymes. RESULTS: The oxidized frying oil feeding produced a significant increase in phase I and II enzyme systems, including the content of CYP450 and microsomal protein, and the activities of NADPH reductase, EROD, PROD, ANH, AMD and QR in rats (P<0.05). In addition, the activities of EROD, ANH and AMD decreased and QR increased after feeding with H. cordata in OFO-fed group (P<0.05). The feeding with 2% H. cordata diet showed the most significant effect. CONCLUSION: The OFO diet induces phases I and II enzyme activity, and the 2% H. cordata diet resulted in a better regulation of the xenobiotic-metabolizing enzyme system. PMID:15637750

The checkered puffer (Spheroides testudineus) and its helminths as bioindicators of chemical pollution in Yucatan coastal lagoons.

PubMed

Pech, Daniel; Vidal-Martínez, Víctor M; Aguirre-Macedo, M Leopoldina; Gold-Bouchot, Gerardo; Herrera-Silveira, Jorge; Zapata-Pérez, Omar; Marcogliese, David J

2009-03-15

The suitability of using helminth communities as bioindicators of environmental quality of the Yucatan coastal lagoons status was tested on the checkered puffer (Spheroides testudineus) in four coastal lagoons along the Yucatan coast. The concentration of chemical pollutants in sediments, water quality parameters, helminth infracommunity characteristics, as well as fish physiological biomarkers, including EROD (7-ethoxyresorufin-O-deethylase) and catalase activities, were measured. Results from sediment analyses demonstrated the presence of hydrocarbons, organochlorine pesticides and polychlorinated biphenyls at varying concentrations, some of which exceeded the Probability Effect Level (PEL). Significant negative associations among organochlorine pesticides, infracommunity characteristics and fish physiological responses were observed in most of the lagoons. Results suggest that EROD activity and parasite infracommunity characteristics could be useful tools to evaluate the effects of chemical pollutants on the fish host and in the environment. Importantly, certain parasites appear to influence biomarker measurements, indicating that parasites should be considered in ecotoxicological studies.

Cytochrome P4501A induction in avian hepatocyte cultures exposed to polychlorinated biphenyls: Comparisons with AHR1-mediated reporter gene activity and in ovo toxicity

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

Manning, Gillian E., E-mail: gmann017@uottawa.ca; Environment Canada, National Wildlife Research Centre, Ottawa, ON, Canada K1A 0H3; Mundy, Lukas J., E-mail: lukas.mundy@ec.gc.ca

2013-01-01

Avian-specific toxic equivalency factors (TEFs) were developed by the World Health Organization to simplify environmental risk assessments of dioxin-like compounds (DLCs), but TEFs do not account for differences in the toxic and biochemical potencies of DLCs among species of birds. Such variability may be due to differences in species sensitivity to individual DLCs. The sensitivity of avian species to DLCs was recently associated with the identity of amino acids 324 and 380 in the aryl hydrocarbon receptor 1 (AHR1) ligand binding domain. A luciferase reporter gene (LRG) assay, measuring AHR1-mediated induction of a cytochrome P450 1A5 (CYP1A5) reporter gene, inmore » combination with a species' AHR1 ligand binding domain sequence, were also shown to predict avian species sensitivity to polychlorinated biphenyls (PCBs) and PCB relative potency in a given species. The goals of the present study were to (1) characterize the concentration-dependent effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin and PCBs 126, 77, 105 and 118 on induction of ethoxyresorufin O-deethylase (EROD) activity and CYP1A4/5 mRNA in chicken, ring-necked pheasant and Japanese quail embryo hepatocytes and (2) compare these in vitro results to those previously generated by the LRG assay and in ovo toxicity studies. EROD activity and CYP1A4/5 mRNA expression data support and complement the findings of the LRG assay. CYP1A enzyme activity and mRNA expression were significantly correlated both with luciferase activity and in ovo toxicity induced by PCBs. Relative potency values were generally similar between the LRG and EROD assays and indicate that the relative potency of some PCBs may differ among species. -- Highlights: ► The chicken isn't the most sensitive species to CYP1A induction by PCB 105 and 118. ► The relative potency of PCBs differs between avian species. ► EROD activity was correlated with luciferase activity from the LRG assay. ► EROD activity was a better predictor of toxicity

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

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

Mundy, Lukas J.; Environment Canada, National Wildlife Research Centre, Ottawa, Ontario; Jones, Stephanie P.

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 themore » 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.« less

Cessation of oil exposure in harlequin ducks after the Exxon Valdez oil spill: Cytochrome P4501A biomarker evidence

USGS Publications Warehouse

Esler, Daniel N.; Ballachey, Brenda E.; Bowen, Lizabeth; Miles, A. Keith; Dickson, Rian D.; Henderson, John D.

2017-01-01

The authors quantified hepatic hydrocarbon-inducible cytochrome P4501A (CYP1A) expression, as ethoxyresorufin-O-deethylase (EROD) activity, in wintering harlequin ducks (Histrionicus histrionicus) captured in Prince William Sound, Alaska (USA), during 2011, 2013, and 2014 (22–25 yr following the 1989 Exxon Valdez oil spill). Average EROD activity was compared between birds from areas oiled by the spill and those from nearby unoiled areas. The present study replicated studies conducted from 1998 to 2009 demonstrating that harlequin ducks using areas oiled in 1989 had elevated EROD activity, indicative of oil exposure, up to 2 decades post spill. In the present study, it was found that average EROD activity during March 2011 was significantly higher in wintering harlequin ducks captured in oiled areas relative to unoiled areas, which the authors interpret to indicate that harlequin ducks continued to be exposed to residual Exxon Valdez oil up to 22 yr after the original spill. However, the 2011 results also indicated reductions in exposure relative to previous years. Average EROD activity in birds from oiled areas was approximately 2 times that in birds from unoiled areas in 2011, compared with observations from 2005 to 2009, in which EROD activity was 3 to 5 times higher in oiled areas. It was also found that average EROD activity during March 2013 and March 2014 was not elevated in wintering harlequin ducks from oiled areas. The authors interpret these findings to indicate that exposure of harlequin ducks to residual Exxon Valdez oil abated within 24 yr after the original spill. The present study finalizes a timeline of exposure, extending over 2 decades, for a bird species thought to be particularly vulnerable to oil contamination in marine environments

Effects of embryonic and adult exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin on hepatic microsomal testosterone hydroxylase activities in great blue herons (Ardea herodias)

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

Sanderson, J.T.; Giesy, J.P.; Janz, D.M.

In a continuing effort to evaluate biomarkers of exposure of great blue herons (Ardea herodias) to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and related halogenated aromatic hydrocarbons, the authors examined the effect of TCDD on hepatic microsomal testosterone hydroxylase activities. Heron embryos were exposed in ovo to 2 {micro}g TCDD/kg egg (or corn oil vehicle) and sacrificed at hatch or 7 d posthatch. Adult herons were exposed intraperitoneally to 20 {micro}g TCDD/kg and sacrificed 2 weeks later. The sex of the birds was known for the adults only. Hepatic microsomes of herons of each age group were able to hydroxylate testosterone at the 2{beta},more » 6{beta}, 15{alpha}, 16{alpha}, or 16{beta} positions. In 7-d-old chicks, an additional unidentified compound was formed. The age of the untreated herons had a strong influence on the activities of the five hydroxylases, with changes of up to 17-fold. The TCDD significantly induced 2{beta}-, 6{beta}, and 15{alpha}-testosterone hydroxylase activities in the adult females, 15{alpha} in the adult males, and 6{beta}-testosterone hydroxylase activity in the hatchlings. In the 7-d-old chicks, induction was no longer apparent. A significant correlation existed between hepatic microsomal ethoxyresorufin O-deethylase (EROD) and 6{beta}-testosterone hydroxylase activity in hatchlings and adult female herons. The TCDD-induced changes in testosterone hydroxylase activities occurred at doses that resulted in tissue concentrations and levels of EROD induction that were environmentally relevant, but did not result in overt toxicities.« less

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

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

Gagnon, M.M.; Bussieres, D.; Dodson, J.J.

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 BKMEmore » 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.« less

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.

The use of biochemical responses to assess ecotoxicological effects of Pharmaceutical and Personal Care Products (PPCPs) after injection in the mussel Elliptio complanata.

PubMed

Martín-Díaz, M Laura; Gagné, François; Blaise, Christian

2009-09-01

A biomarker approach was undertaken using the mussel Elliptio complanata to assess the ecotoxicological effects after injection of a range concentration (0-10mM) of three different PPCPs: carbamazepine, caffeine, methotrexate; and an effluent extract (C8) from St. Lawrence wastewaters treatment plant (Montreal, Canada). A battery of biomarkers, involving oxidative stress and genotoxicity responses: glutation-S-transferase (GST), ethoxyresorufin O-deethylase (EROD), dibenzylflourescein dealkylase (DBF), xanthine oxidoreductase (XOR) activities, lipid peroxidation (LPO) and DNA damage were determined in gonad and digestive gland tissues after 48 h of injection. Results showed an induction of the oxidative metabolism with increasing pharmaceutical concentration in those mussels injected with the PPCPs and the effluent extract. Phase I detoxification enzymes were significantly induced (p<0.05), concretely DBF activity was significantly induced after caffeine, carbamazipine and C8 injection; and EROD activity after C8 and methotrexate injection. Oxidative stress induction only lead to lipid peroxidation (p<0.05) in organisms injected with carbamazepine and caffeine and DNA damage in organisms injected with methotrexate (p<0.05). EROD and DBF enzymatic activities have been found to be suitable biomarkers to determine bioavailability of pharmaceuticals. LPO and DNA damage to determine possible associated adverse effects. Nevertheless, their validation in realistic exposure scenarios and under exposure conditions should be performed in future research.

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-Renier, Natalie K.; 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.

Manure effects on soil N in eroded and non-eroded, sprinkler-irrigated soil

USDA-ARS?s Scientific Manuscript database

Manure effects on nitrate-N transport through irrigated, low-organic matter calcareous soil are not well known. This field study quantified the effects of a one-time fall application of stockpiled dairy manure and urea on in-season and over-winter nitrate-N transport through non-eroded and eroded (...

Pyrosequencing reveals bacteria carried in different wind-eroded sediments.

PubMed

Gardner, Terrence; Acosta-Martinez, Veronica; Calderón, Francisco J; Zobeck, Ted M; Baddock, Matthew; Van Pelt, R Scott; Senwo, Zachary; Dowd, Scot; Cox, Stephen

2012-01-01

Little is known about the microbial communities carried in wind-eroded sediments from various soil types and land management systems. The novel technique of pyrosequencing promises to expand our understanding of the microbial diversity of soils and eroded sediments because it can sequence 10 to 100 times more DNA fragments than previous techniques, providing enhanced exploration into what microbes are being lost from soil due to wind erosion. Our study evaluated the bacterial diversity of two types of wind-eroded sediments collected from three different organic-rich soils in Michigan using a portable field wind tunnel. The wind-eroded sediments evaluated were a coarse sized fraction with 66% of particles >106 μm (coarse eroded sediment) and a finer eroded sediment with 72% of particles <106 μm. Our findings suggested that (i) bacteria carried in the coarser sediment and fine dust were effective fingerprints of the source soil, although their distribution may vary depending on the soil characteristics because certain bacteria may be more protected in soil surfaces than others; (ii) coarser wind-eroded sediment showed higher bacterial diversity than fine dust in two of the three soils evaluated; and (iii) certain bacteria were more predominant in fine dust (, , and ) than coarse sediment ( and ), revealing different locations and niches of bacteria in soil, which, depending on wind erosion processes, can have important implications on the soil sustainability and functioning. Infrared spectroscopy showed that wind erosion preferentially removes particular kinds of C from the soil that are lost via fine dust. Our study shows that eroded sediments remove the active labile organic soil particulates containing key microorganisms involved in soil biogeochemical processes, which can have a negative impact on the quality and functioning of the source soil. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America

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

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

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 dosesmore » {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.« less

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. Copyright (c) 2010 SETAC.

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

USGS Publications Warehouse

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

2010-01-01

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.

Quantitative evaluation of hepatic cytochrome P4501A transcript, protein, and catalytic activity in the striped sea bream (Lithognathus mormyrus).

PubMed

Tom, Moshe; Shmul, Merav; Shefer, Edna; Chen, Nir; Slor, Hanoch; Rinkevich, Baruch; Herut, Barak

2003-09-01

Hepatic cytochrome P4501A (CYP1A) expression was partially characterized in the striped sea bream (Lithognathus mormyrus) from the Mediterranean coast of Israel as part of the process of establishing the CYP1A gene as an environmental biomarker. Reverse transcription-competitive polymerase chain reaction, competitive enzyme-linked immunosorbent assay, and ethoxyresorufin O-deethylase (EROD) assay were used for evaluating transcript, protein, and catalytic activity levels, respectively, in absolute units. Highest elucidated transcript, protein, and catalytic activity levels were 0.264 +/- SD 0.084 fmol/microg total RNA, 0.88 +/- 0.52 pmol/microg total protein, and 1.11 +/- 0.52 pmol resorufin/min/microg total protein, respectively, and the lower levels were 0.009 +/- 0.007 fmol/microg total RNA, 0.17 +/- 0.08 pmol/microg total protein, and 0.11 +/- 0.06 pmol resorufin/min/microg total protein, respectively, demonstrating substantial induction potential. All alternate pairs of seven examined field samples, revealing a transcript-level ratio higher than 1.7, also demonstrated a significant difference between their transcript levels, indicating a potential to detect relatively small biomarker changes (1.7-fold) caused by environmental effects. Simultaneous triple measurements of transcript, protein, and catalytic activity were carried out in individuals from two field samples and during a 318-d decay experiment. Fish from the field samples revealed significant alternate bivariate correlation between transcript, protein, and enzymatic activity. Conflicting results were found when analyzing the decay experiment, in which both protein and catalytic activity levels decreased significantly to basal levels, in contrast to no significant change in transcript levels throughout the experiment. No significant difference was observed between males and females regarding the levels of CYP1A transcript, protein, and EROD.

A bleached-kraft mill effluent fraction causing induction of a fish mixed-function oxygenase enzyme

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

Burnison, B.K.; Hodson, P.V.; Nuttley, D.J.

1996-09-01

Pulp mill effluents contain a myriad of chemicals that have the potential to cause deleterious effects on aquatic biota in receiving waters. Some of these chemicals evoke an acute lethal response of exposed biota while others evoke sublethal responses. One such sublethal response is the induction of mixed-function oxygenases (MFO) in fish, specifically the CYP1A1 enzyme ethoxy-resorufin-o-deethylase (EROD). Compounds causing MFO induction include congeners of polychlorinated biphenyls (PCBs), dioxins, furans, and polycyclic aromatic hydrocarbons (PAHs). The authors followed the partitioning of the inducing chemicals in pulp mill effluent fractions by Toxicity Identification Evaluation (TIE), or bioassay-driven chemical analysis. This proceduremore » was eventually modified to a more direct technique involving centrifugation, filtration, cleanup procedures, and C{sub 18} solid-phase adsorption. The extracts from the fractionation of two pulp mill effluents after secondary treatment were tested for EROD-inducing activity in a 4-d rainbow trout bioassay. The methanol extracts of particulates/colloids showed significant inducing capacity in Mill A effluent but not in Mill B effluent. The C{sub 18} methanol extracts induced activity from both effluents, with extracts from Mill A causing the greatest response. The particulate/colloidal extract (Mill A) was used as the source material for chemicals which caused EROD induction. The fraction was purified by solid-phase extraction techniques and reverse-phase high-performance liquid chromatography. The majority of the EROD activity was found in the moderately nonpolar region of the chromatogram (K{sub ow} = 4.6 to 5.1).« less

Polycyclic aromatic hydrocarbon-induced CYP1B1 activity is suppressed by perillyl alcohol in MCF-7 cells

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

Chan, Nelson L.S.; Wang Huan; Wang Yun

2006-06-01

Perillyl alcohol (POH) is a dietary monoterpene with potential applications in chemoprevention and chemotherapy. Although clinical trials are under way, POH's physiological and pharmacological properties are still unclear. In the present study, the effect of POH on polycyclic aromatic hydrocarbon (PAH)-induced genotoxicity, and the related expression were examined in MCF-7 cells. Exposure to environmental toxicant increases the risk of cancer. Many of these compounds are pro-carcinogens and are biotransformed into their ultimate genotoxic structures by xenobiotic metabolizing enzymes. CYP1A1 and 1B1 are enzymes that catalyze the biotransformation of dimethylbenz[a]anthracene (DMBA). Our data revealed that 0.5 {mu}M of POH was effectivemore » in blocking DMBA-DNA binding. Ethoxyresorufin-O-deethylase (EROD) assay indicated that the administration of POH inhibited the DMBA-induced enzyme activity in MCF-7 cells. Enzyme kinetic analysis revealed that POH inhibited CYP1B1 but not CYP1A1 activity. Quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) assay also demonstrated that the monoterpene reduced CYP1B1 mRNA abundance induced by DMBA. The present study illustrated that POH might inhibit and downregulate CYP1B1, which could protect against PAH-induced carcinogenesis.« less

Polycyclic aromatic hydrocarbon-induced CYP1B1 activity is suppressed by perillyl alcohol in MCF-7 cells.

PubMed

Chan, Nelson L S; Wang, Huan; Wang, Yun; Leung, Hau Yi; Leung, Lai K

2006-06-01

Perillyl alcohol (POH) is a dietary monoterpene with potential applications in chemoprevention and chemotherapy. Although clinical trials are under way, POH's physiological and pharmacological properties are still unclear. In the present study, the effect of POH on polycyclic aromatic hydrocarbon (PAH)-induced genotoxicity, and the related expression were examined in MCF-7 cells. Exposure to environmental toxicant increases the risk of cancer. Many of these compounds are pro-carcinogens and are biotransformed into their ultimate genotoxic structures by xenobiotic metabolizing enzymes. CYP1A1 and 1B1 are enzymes that catalyze the biotransformation of dimethylbenz[a]anthracene (DMBA). Our data revealed that 0.5 microM of POH was effective in blocking DMBA-DNA binding. Ethoxyresorufin-O-deethylase (EROD) assay indicated that the administration of POH inhibited the DMBA-induced enzyme activity in MCF-7 cells. Enzyme kinetic analysis revealed that POH inhibited CYP1B1 but not CYP1A1 activity. Quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) assay also demonstrated that the monoterpene reduced CYP1B1 mRNA abundance induced by DMBA. The present study illustrated that POH might inhibit and downregulate CYP1B1, which could protect against PAH-induced carcinogenesis.

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

Experimental Study of Factors Affecting Soil Erodibility

NASA Astrophysics Data System (ADS)

Larionov, G. A.; Bushueva, O. G.; Gorobets, A. V.; Dobrovolskaya, N. G.; Kiryukhina, Z. P.; Krasnov, S. F.; Litvin, L. F.; Maksimova, I. A.; Sudnitsyn, I. I.

2018-03-01

The effect of different factors and preparation conditions of monofraction samples from the arable horizon of leached chernozem on soil erodibility and its relationship with soil tensile strength (STS) has been studied. The exposure of samples at 38°C reduces their erodibility by two orders of magnitude. The drying of samples, on the contrary, increases their erodibility. It has been shown that erodibility decreases during the experiment. It has been found that the inoculation of soil with yeast cultures ( Naganishia albida, Lipomyces tetrasporus) reliably increases the STS value in 1.5-1.9 times. The sterile soil is eroded more intensively than the unsterile soil: at 4.9 and 0.3 g/(m2 s), respectively. The drying of soil followed by wetting to the initial water content (30%) has no significant effect on the STS value in almost all experimental treatments.

Toxicological responses on cytochrome P450 and metabolic transferases in liver of goldfish (Carassius auratus) exposed to lead and paraquat.

PubMed

Xu, Xiaoming; Cui, Zhaojie; Wang, Xinlei; Wang, Xixin; Zhang, Su

2018-04-30

As the producer of reactive oxygen species (ROS), both lead (Pb) and paraquat (PQ) can generate serious oxidative stress in target organs which result in irreversible toxic effects on organisms. They can disturb the normal catalytic activities of many enzymes by means of different toxicity mechanism. The changed responses of enzymes are frequently used as the biomarkers for indicating the relationship between toxicological effects and exposure levels. In this work, goldfish was exposed to a series of test groups containing lead and paraquat in the range of 0.05-10mg/L, respectively. Four hepatic enzyme activities, including 7-ethoxyresorufinO-deethylase (EROD), 7-benzyloxy-4-trifluoromethyl-coumarin-O-debenzyloxylase (BFCOD), glutathione S-transferase (GST) and UDP-glucuronosyltransferase (UGT) were determined after 1, 7, 14, 28 days exposure. The results showed that the activities of EROD and BFCOD in fish were significantly inhibited in response to paraquat at all exposure levels during the whole experiment. Similarly, the inhibitory effects of lead exposure on BFCOD activity were found in our study, while different responses of lead on EROD were observed. There were no significant differences on EROD activity under lower concentrations of lead (less than 0.1mg/L) before 14 days until an obvious increase was occurred for the 0.5mg/L lead treatment group at day 14. Furthermore, lead showed stronger inhibition on GST activity than paraquat when the concentrations of the two toxicants were more than 0.5mg/L. However, the similar dose and time-dependent manners of UGT activity were found under lead and paraquat exposure. Our results indicated that higher exposure levels and longer accumulations caused inhibitory effects on the four enzymes regardless of lead or paraquat stress. In addition, the responses of phase I enzymes were more sensitive than that of phase II enzymes and they may be served as the acceptable biomarkers for evaluating the toxicity effects of both

Tissue distribution of zinc and subtle oxidative stress effects after dietary administration of ZnO nanoparticles to rainbow trout.

PubMed

Connolly, Mona; Fernández, Marta; Conde, Estefanía; Torrent, Fernando; Navas, José M; Fernández-Cruz, María L

2016-05-01

The increasing use of ZnO nanoparticles (ZnO NPs) in different fields has raised concerns about the possible environmental risks associated with these NPs entering aquatic systems. In this study, using a dietary exposure route, we have analysed the tissue distribution and depuration pattern of Zn as well as any associated redox balance disturbances in rainbow trout (Oncorhynchus mykiss) following exposure to ZnO NPs (20-30nm). Fish were fed a diet spiked with ZnO NPs prepared from a dispersion in sunflower oil at doses of 300 or 1000mg ZnO NPs/kg feed for 10days. This uptake phase was followed by a 28days depuration phase in which fish from all groups received untreated feed. While no overt signs of toxicity were observed and no important effects in fish growth (weight and length) or in the hepatosomatic index among groups were recorded, we observed high levels of Zn bioaccumulation in the gills and intestine of exposed fish following exposure to both dose levels. Zn levels were not eliminated during the depuration phase and we have evidenced oxidative stress responses in gills associated with such long term ZnO NPs bioaccumulation and lack of elimination. Furthermore, exposures to higher doses of ZnO NPs (1000mg/kg feed) resulted in Zn distribution to the liver of fish following 10days of exposure. Fish from this exposure group experienced biochemical disturbances associated with oxidative stress in the liver and ethoxy-resorufin-O-deethylase (EROD) activity which may point to the ability of ZnO NPs or its ions to interfere with cytochrome P450 metabolic processes. Copyright © 2016 Elsevier B.V. All rights reserved.

Effects of pentachlorophenol on the quail (Coturnix japonica) liver detoxification pathway.

PubMed

Jiang, Peng; Wang, Jianshe; Sheng, Nan; Wei, Dongbing; Dai, Jiayin

2017-06-01

Pentachlorophenol (PCP), an extensively used pesticide and biocide, is of critical environmental concern due to its toxicity and recalcitrance to degradation. In this study, the effect of PCP on induction of transcription factors, cytochrome P450 (CYP450) genes, and the antioxidative enzyme system were investigated in the quail liver. A total of 60 (4- to 6-week-old) male quails (Coturnix japonica) were administered 0, 0.05, 0.5, and 5 mg/kg/d PCP orally for 42 d. Following exposure, both absolute and relative liver weights were significantly lower than those of the control. Using gas chromatography-mass spectrometry, PCP accumulation was, from highest to lowest, kidney > liver > muscle for all exposure groups. The expressions of CYP1A5, CYP1B1, CYP2C18, nuclear translocator 1 (ARNT1), and aryl hydrocarbon receptor 1 (AHR1) were induced after PCP treatment, and increases were found in the activities of hepatic superoxide dismutase (SOD) and catalase (CAT), and the content of hepatic malondialdehyde (MDA). In addition, exposure to PCP induced an increase in liver 8-hydroxydeoxyguanosine (8-OHdG) and significantly elevated ethoxyresorufin O-deethylase (EROD), methoxyresorufin O-demethylase (MROD), and 7-ethoxycoumarin-O-deethylase (ECOD) activity, but decreased that of glutathione peroxidase (GSH-Px), benzyloxyresorufin O-debenzylase (BROD), pentoxyresorufin O-depentylase (PROD), and erythromycin N-demethylase (END). No significant responses were observed for benzyloxy-trifluoromethyl-coumarin (BFC). The protein level of liver nuclear factor κB (NF-κB) was higher, whereas that of nuclear factor E2-related factor 2 (Nrf2) was lower for exposed quail. These results suggest that PCP affects quail oxidative stress by modulating CYP450 enzymes and nuclear transcription factors. Copyright © 2017 Elsevier Ltd. All rights reserved.

Cessation of oil exposure in harlequin ducks after the Exxon Valdez oil spill: Cytochrome P4501A biomarker evidence.

PubMed

Esler, Daniel; Ballachey, Brenda E; Bowen, Lizabeth; Miles, A Keith; Dickson, Rian D; Henderson, John D

2017-05-01

The authors quantified hepatic hydrocarbon-inducible cytochrome P4501A (CYP1A) expression, as ethoxyresorufin-O-deethylase (EROD) activity, in wintering harlequin ducks (Histrionicus histrionicus) captured in Prince William Sound, Alaska (USA), during 2011, 2013, and 2014 (22-25 yr following the 1989 Exxon Valdez oil spill). Average EROD activity was compared between birds from areas oiled by the spill and those from nearby unoiled areas. The present study replicated studies conducted from 1998 to 2009 demonstrating that harlequin ducks using areas oiled in 1989 had elevated EROD activity, indicative of oil exposure, up to 2 decades post spill. In the present study, it was found that average EROD activity during March 2011 was significantly higher in wintering harlequin ducks captured in oiled areas relative to unoiled areas, which the authors interpret to indicate that harlequin ducks continued to be exposed to residual Exxon Valdez oil up to 22 yr after the original spill. However, the 2011 results also indicated reductions in exposure relative to previous years. Average EROD activity in birds from oiled areas was approximately 2 times that in birds from unoiled areas in 2011, compared with observations from 2005 to 2009, in which EROD activity was 3 to 5 times higher in oiled areas. It was also found that average EROD activity during March 2013 and March 2014 was not elevated in wintering harlequin ducks from oiled areas. The authors interpret these findings to indicate that exposure of harlequin ducks to residual Exxon Valdez oil abated within 24 yr after the original spill. The present study finalizes a timeline of exposure, extending over 2 decades, for a bird species thought to be particularly vulnerable to oil contamination in marine environments. Environ Toxicol Chem 2017;36:1294-1300. Published 2016 Wiley Periodicals Inc. on behalf of SETAC. This article is a US government work and, as such, is in the public domain in the United States of America

EROD activity, chromosomal damage, and oxidative stress in response to contaminants exposure in tree swallow (Tachycineta bicolor) nestlings from Great Lakes Areas of Concern

USGS Publications Warehouse

Custer, Thomas W.; Custer, Christine M.; Dummer, Paul; Bigorgne, Emilie; Oziolor, Elias; Karouna-Renier, Natalie K.; Schultz, Sandra; Erickson, Richard A.; Aagaard, Kevin; Matson, Cole W.

2017-01-01

Tree swallow, Tachycineta bicolor, nestlings were collected from 60 sites in the Great Lakes, which included multiple sites within 27 Areas of Concern (AOCs) and six sites not listed as AOCs from 2010 to 2014. Nestlings, approximately 12 days-of-age, were evaluated for ethoxyresorufin-O-dealkylase (EROD) activity, chromosomal damage, and six measures of oxidative stress. Data on each of these biomarkers were divided into four equal numbered groups from the highest to lowest values and the groups were compared to contaminant concentrations using multivariate analysis. Contaminant concentrations, from the same nestlings, included polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), perfluorinated compounds (PFCs), and 17 elements. Alkylated polycyclic aromatic hydrocarbons (aPAHs) and parent PAHs (pPAHs) were measured in pooled nestling dietary samples. Polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans, and pesticides were measured in sibling eggs. Concentrations of aPAHs, pPAHs, chlordane, dieldrin, heptachlor, and PCBs, in that order, were the major contributors to the significant differences between the lowest and highest EROD activities; PFCs, PBDEs, the remaining pesticides, and all elements were of secondary importance. The four categories of chromosomal damage did not separate out well based on the contaminants measured. Concentrations of aPAHs, pPAHs, heptachlor, PCBs, chlordane, and dieldrin were the major contributors to the significant differences between the lowest and highest activities of two oxidative stress measures, total sulfhydryl (TSH) activity and protein bound sulfhydryl (PBSH) activity. The four categories of thiobarbituric acid reacting substances (TBARS), oxidized glutathione (GSSG), reduced glutathione (GSH), and the ratio of GSSG/GSH did not separate well based on the contaminants measured.

EROD activity, chromosomal damage, and oxidative stress in response to contaminants exposure in tree swallow (Tachycineta bicolor) nestlings from Great Lakes Areas of Concern.

PubMed

Custer, Thomas W; Custer, Christine M; Dummer, Paul M; Bigorgne, Emilie; Oziolor, Elias M; Karouna-Renier, Natalie; Schultz, Sandra; Erickson, Richard A; Aagaard, Kevin; Matson, Cole W

2017-12-01

Tree swallow, Tachycineta bicolor, nestlings were collected from 60 sites in the Great Lakes, which included multiple sites within 27 Areas of Concern (AOCs) and six sites not listed as AOCs from 2010 to 2014. Nestlings, approximately 12 days-of-age, were evaluated for ethoxyresorufin-O-dealkylase (EROD) activity, chromosomal damage, and six measures of oxidative stress. Data on each of these biomarkers were divided into four equal numbered groups from the highest to lowest values and the groups were compared to contaminant concentrations using multivariate analysis. Contaminant concentrations, from the same nestlings, included polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), perfluorinated compounds (PFCs), and 17 elements. Alkylated polycyclic aromatic hydrocarbons (aPAHs) and parent PAHs (pPAHs) were measured in pooled nestling dietary samples. Polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans, and pesticides were measured in sibling eggs. Concentrations of aPAHs, pPAHs, chlordane, dieldrin, heptachlor, and PCBs, in that order, were the major contributors to the significant differences between the lowest and highest EROD activities; PFCs, PBDEs, the remaining pesticides, and all elements were of secondary importance. The four categories of chromosomal damage did not separate out well based on the contaminants measured. Concentrations of aPAHs, pPAHs, heptachlor, PCBs, chlordane, and dieldrin were the major contributors to the significant differences between the lowest and highest activities of two oxidative stress measures, total sulfhydryl (TSH) activity and protein bound sulfhydryl (PBSH) activity. The four categories of thiobarbituric acid reacting substances (TBARS), oxidized glutathione (GSSG), reduced glutathione (GSH), and the ratio of GSSG/GSH did not separate well based on the contaminants measured.

Monitoring of dioxin-like, estrogenic and anti-androgenic activities in sediments of the Bizerta lagoon (Tunisia) by means of in vitro cell-based bioassays: contribution of low concentrations of polynuclear aromatic hydrocarbons (PAHs).

PubMed

Louiz, I; Kinani, S; Gouze, M-E; Ben-Attia, M; Menif, D; Bouchonnet, S; Porcher, J M; Ben-Hassine, O K; Aït-Aïssa, S

2008-09-01

We used an array of in vitro cell-based bioassays to assess dioxin-like, estrogenic and (anti-)androgenic activities in organic extracts of sediments from the Bizerta lagoon, one of the largest Tunisian lagoons subjected to various anthropogenic and industrial pressures. The sediments were sampled both in winter and summer 2006 in 6 stations differently impacted and in one reference station located in the seawards entrance of Ghar el Melh lagoon. Chemical analyses of the 16 priority PAHs showed that the sediments were low to moderately contaminated (2-537 ng/g dry weight). By using the estrogen- (MELN) and androgen-responsive (MDA-kb2) reporter cell lines, significant estrogenic and anti-androgenic activities were detected only in the Menzel Bourguiba (MB) site, the most contaminated site, both in winter and summer. By using 7-ethoxyresorufin-O-deethylase (EROD) induction in the fish PLHC-1 cell line after both 4 and 24 h of cell exposure, dioxin-like activities were detected in all analysed samples. Dioxin-like activities were higher after 4 h exposure, and varied according to the sites and the sampling season. While highly significant correlation was observed between bioassay- and chemical analyses-derived toxic equivalents (TEQs), PAHs accounted for only a small part (up to 4%) of the detected biological activities, suggesting that other readily metabolised EROD-inducing compounds were present. This study argues for the use of short time exposure to assess biological TEQs in low contaminated samples and provides new induction equivalent factors (IEF(4h)) for 16 PAHs in the PLHC-1 cell line. Finally, our results stress the need to further characterise the nature of organic chemical contamination as well as its long-term impacts on aquatic wildlife in the Bizerta lagoon.

Soil erodibility for water erosion: A perspective and Chinese experiences

NASA Astrophysics Data System (ADS)

Wang, Bin; Zheng, Fenli; Römkens, Mathias J. M.; Darboux, Frédéric

2013-04-01

Knowledge of soil erodibility is an essential requirement for erosion prediction, conservation planning, and the assessment of sediment related environmental effects of watershed agricultural practices. This paper reviews the status of soil erodibility evaluations and determinations based on 80 years of upland area erosion research mainly in China and the USA. The review synthesizes the general research progress made by discussing the basic concepts of erodibility and its evaluation, determination, and prediction as well as knowledge of its spatio-temporal variations. The authors found that soil erodibility is often inappropriately or inaccurately applied in describing soil loss caused by different soil erosion component processes and mechanisms. Soil erodibility indicators were related to intrinsic soil properties and exogenic erosional forces, measurements, and calculations. The present review describes major needs including: (1) improved definition of erodibility, (2) modified erodibility determinations in erosion models, especially for specific geographical locations and in the context of different erosion sub-processes, (3) advanced methodologies for quantifying erodibilities of different soil erosion sub-processes, and (4) a better understanding of the mechanism that causes temporal variations in soil erodibility. The review also provides a more rational basis for future research on soil erodibility and supports predictive modeling of soil erosion processes and the development of improved conservation practices.

Xenobiotic metabolism in the fish hepatic cell lines Hepa-E1 and RTH-149, and the gill cell lines RTgill-W1 and G1B: Biomarkers of CYP450 activity and oxidative stress.

PubMed

Franco, Marco E; Sutherland, Grace E; Lavado, Ramon

2018-04-01

The use of fish cell cultures has proven to be an effective tool in the study of environmental and aquatic toxicology. Valuable information can be obtained from comparisons between cell lines from different species and organs. In the present study, specific chemicals were used and biomarkers (e.g. 7-Ethoxyresorufin-O-deethylase (EROD) activity and reactive oxygen species (ROS)) were measured to assess the metabolic capabilities and cytotoxicity of the fish hepatic cell lines Hepa-E1 and RTH-149, and the fish gill cell lines RTgill-W1 and G1B. These cell lines were exposed to β-naphthoflavone (BNF) and benzo[a]pyrene (BaP), the pharmaceutical tamoxifen (TMX), and the organic peroxide tert-butylhydroperoxide (tBHP). Cytotoxicity in gill cell lines was significantly higher than in hepatic cells, with BNF and TMX being the most toxic compounds. CYP1-like associated activity, measured through EROD activity, was only detected in hepatic cells; Hepa-E1 cells showed the highest activity after exposure to both BNF and BaP. Significantly higher levels of CYP3A-like activity were also observed in Hepa-E1 cells exposed to TMX, while gill cell lines presented the lowest levels. Measurements of ROS and antioxidant enzymes indicated that peroxide levels were higher in gill cell lines in general. However, levels of superoxide were significantly higher in RTH-149 cells, where no distinctive increase of superoxide-related antioxidants was observed. The present study demonstrates the importance of selecting adequate cell lines in measuring specific metabolic parameters and provides strong evidence for the fish hepatocarcinoma Hepa-E1 cells to be an excellent alternative in assessing metabolism of xenobiotics, and in expanding the applicability of fish cell lines for in vitro studies. Copyright © 2018 Elsevier Inc. All rights reserved.

7 CFR 12.21 - Identification of highly erodible lands criteria.

Code of Federal Regulations, 2011 CFR

2011-01-01

...) Basis for identification as highly erodible. Soil map units and an erodibility index will be used as the basis for identifying highly erodible land. The erodibility index for a soil is determined by dividing the potential average annual rate of erosion for each soil by its predetermined soil loss tolerance (T...

7 CFR 12.21 - Identification of highly erodible lands criteria.

Code of Federal Regulations, 2012 CFR

2012-01-01

...) Basis for identification as highly erodible. Soil map units and an erodibility index will be used as the basis for identifying highly erodible land. The erodibility index for a soil is determined by dividing the potential average annual rate of erosion for each soil by its predetermined soil loss tolerance (T...

7 CFR 12.21 - Identification of highly erodible lands criteria.

Code of Federal Regulations, 2013 CFR

2013-01-01

...) Basis for identification as highly erodible. Soil map units and an erodibility index will be used as the basis for identifying highly erodible land. The erodibility index for a soil is determined by dividing the potential average annual rate of erosion for each soil by its predetermined soil loss tolerance (T...

7 CFR 12.21 - Identification of highly erodible lands criteria.

Code of Federal Regulations, 2014 CFR

2014-01-01

...) Basis for identification as highly erodible. Soil map units and an erodibility index will be used as the basis for identifying highly erodible land. The erodibility index for a soil is determined by dividing the potential average annual rate of erosion for each soil by its predetermined soil loss tolerance (T...

7 CFR 12.21 - Identification of highly erodible lands criteria.

Code of Federal Regulations, 2010 CFR

2010-01-01

...) Basis for identification as highly erodible. Soil map units and an erodibility index will be used as the basis for identifying highly erodible land. The erodibility index for a soil is determined by dividing the potential average annual rate of erosion for each soil by its predetermined soil loss tolerance (T...

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. (a...

Soil quality changes after topsoil addition to eroded land

USDA-ARS?s Scientific Manuscript database

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...

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, Paul 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).

Are deep-sea organisms dwelling within a submarine canyon more at risk from anthropogenic contamination than those from the adjacent open slope? A case study of Blanes canyon (NW Mediterranean)

NASA Astrophysics Data System (ADS)

Koenig, Samuel; Fernández, Pilar; Company, Joan B.; Huertas, David; Solé, Montserrat

2013-11-01

Due to their geomorphological structure and proximity to the coastline, submarine canyons may act as natural conduit routes for anthropogenic contaminants that are transported from surface waters to the deep-sea. Organisms dwelling in these canyon environments might thus be at risk of experiencing adverse health effects due to higher pollution exposure. To address this question, chemical and biochemical analyses were conducted on two of the most abundant deep-sea fish species in the study area, namely Alepocephalus rostratus and Lepidion lepidion, and the most abundant deep-sea commercial decapod crustacean Aristeus antennatus sampled inside Blanes canyon (BC) and on the adjacent open slope (OS). Persistent organic pollutants (POPs) levels, including polychlorinated biphenyl (PCB), dichlorodiphenyltrichloroethane (DDT) and derivatives, hexachlorocyclohexanes (HCHs) and hexachlorobenzene (HCB) were determined in muscle tissue of selected samples from 900 m and 1500 m depth. Potential effects resulting from contaminant exposure were determined using hepatic biomarkers such as ethoxyresorufin-O-deethylase (EROD), pentoxyresorufin-O-deethylase (PROD), catalase (CAT), carboxylesterase (CbE), glutathione-S-transferase (GST), total glutathione peroxidase (GPX), glutathione reductase (GR) and superoxide-dismutase (SOD) enzyme activities and lipid peroxidation levels (LP). L. lepidion and A. antennatus tissues exhibited higher POP levels inside BC compared to the OS at 900 m depth. These findings were consistent with biomarker data (i.e. enzymatic response to presence of contaminant agents). Elevated xenobiotic-metabolizing (EROD and PROD) and antioxidant enzymes (CAT and GPX) indicated higher contaminant exposure in both species caught within BC. No difference in POP accumulation between sites was observed in L. lepidion at 1500 m depth, nor in biomarker data, suggesting that the pollution gradient was less pronounced at greater depths. This trend was further corroborated

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. Copyright © 2014 The Authors. Published by Elsevier Ltd.. All rights reserved.

Microsomal enzyme activities in beluga whales from the Mackenzie River Delta, Northwest Territories, Canada

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

Lockhart, L.; Metner, D.; Muir, D.

1995-12-31

On two occasions the authors have obtained samples of liver from freshly killed beluga whales harvested by Inuit hunters. The first samples were obtained from whales trapped in the Husky Lakes; with the onset of winter, ice restricted these whales to small breathing holes where they were taken by hunters. They were found to be starving, with body weights about 200 kg less than those expected for whales of their length. Liver mixed-function oxygenase activities, ethoxyresorufin-O-deethylase and aryl hydrocarbon hydroxylase, correlated closely with blubber residues of polychlorinated biphenyls. A second group of whales was taken in the summer hunt inmore » Kugmallit Bay and showed no sign of starvation. The enzyme activities in these whales had weaker statistical relationships to PCB residues. These observations suggested that mobilization of blubber by the starving whales may have released PCBs to act pharmacologically. The authors could not test this hypothesis directly on whales, but an experiment was carried out on laboratory fish to try to examine it. Arctic char were given low dosages of PCB congener 126 and then maintained on diets of full normal ration, half-ration and quarter-ration over a period of 48 weeks, with sub-sampling at intervals. Fish receiving less than maintenance rations responded with decreases in body fat and increases in EROD activities. These laboratory results suggest that correlations between enzymatic activities and PCBs in the starving whales may indeed have been the result of the loss of blubber and concomitant release of PCBs.« less

Biomarkers and bioindicators of the environmental condition using a fish species (Pimelodus maculatus Lacepède, 1803) in a tropical reservoir in Southeastern Brazil.

PubMed

Araújo, F G; Morado, C N; Parente, T T E; Paumgartten, F J R; Gomes, I D

2018-05-01

The Funil Reservoir receives a large amount of xenobiotics from the Paraíba do Sul River (PSR) from large number of industries and municipalities in the watershed. This study aimed to assess environmental quality along the longitudinal profile of the Paraíba do Sul River-Funil Reservoir system, by using biomarkers and bioindicators in a selected fish species. The raised hypothesis is that Funil Reservoir acts as a filter for the xenobiotics of the PSR waters, improving river water quality downstream the dam. Two biomarkers, the ethoxyresorufin-O-deethylase activity (EROD), measured as fluorimetricly in S9 hepatic fraction, and the micronuclei frequency (MN), observed in erythrocytes of the cytoplasm, and three bioindicators, the hepatosomatic index (HSI), gonadosomatic index (GSI) and condition factor (CF) were used in Pimelodus maculatus, a fish species widely distributed in the system. Four zones were searched through a longitudinal gradient: 1, river upstream from the reservoir; 2, upper reservoir; 3, lower reservoir; 4, river downstream of the reservoir. EROD activity and HSI and GSI had significant differences among the zones (P<0.05). The upper reservoir had the lowest EROD activity and HSI, whereas the river downstream of the reservoir had the highest EROD and lowest GSI. The river upstream from the reservoir showed the highest HSI and GSI. It is suggested that the lowest environmental condition occur at the river downstream of the reservoir, where it seems to occur more influence of xenobiotics, which could be associated with hydroelectric plant operation. The hypothesis that Funil reservoir acts as a filter decanting pollution from the Paraíba do Sul River waters was rejected. These results are novel information on this subject for a native fish species and could be useful for future comparisons with other environments.

Soil erodibility variability in laboratory and field rainfall simulations

NASA Astrophysics Data System (ADS)

Szabó, Boglárka; Szabó, Judit; Jakab, Gergely; Centeri, Csaba; Szalai, Zoltán

2017-04-01

Rainfall simulation experiments are the most common way to observe and to model the soil erosion processes in in situ and ex situ circumstances. During modelling soil erosion, one of the most important factors are the annual soil loss and the soil erodibility which represent the effect of soil properties on soil loss and the soil resistance against water erosion. The amount of runoff and soil loss can differ in case of the same soil type, while it's characteristics determine the soil erodibility factor. This leads to uncertainties regarding soil erodibility. Soil loss and soil erodibility were examined with the investigation of the same soil under laboratory and field conditions with rainfall simulators. The comparative measurement was carried out in a laboratory on 0,5 m2, and in the field (Shower Power-02) on 6 m2 plot size where the applied slope angles were 5% and 12% with 30 and 90 mm/h rainfall intensity. The main idea was to examine and compare the soil erodibility and its variability coming from the same soil, but different rainfall simulator type. The applied model was the USLE, nomograph and other equations which concern single rainfall events. The given results show differences between the field and laboratory experiments and between the different calculations. Concerning for the whole rainfall events runoff and soil loss, were significantly higher at the laboratory experiments, which affected the soil erodibility values too. The given differences can originate from the plot size. The main research questions are that: How should we handle the soil erodibility factors and its significant variability? What is the best solution for soil erodibility determination?

Seasonal variations in erodibility and sediment transport potential in a mesotidal channel-flat complex, Willapa Bay, WA

NASA Astrophysics Data System (ADS)

Wiberg, Patricia L.; Law, Brent A.; Wheatcroft, Robert A.; Milligan, Timothy G.; Hill, Paul S.

2013-06-01

Measurements of erodibility, porosity and sediment size were made three times over the course of a year at sites within a muddy, mesotidal flat-channel complex in southern Willapa Bay, WA, to examine spatial and seasonal variations in sediment properties and transport potential. Average critical shear stress profiles, the metric we used for erodibility, were quantified using a power-law fit to cumulative eroded mass vs. shear stress for the flats and channel. Laboratory erosion measurements of deposits made from slurries of flat and channel sediment were used to quantify erodibility over consolidation time scales ranging from 6 to 96h. Erodibility of the tidal flats was consistently low, with spatial variability comparable to seasonal variability despite seasonal changes in biological activity. In contrast, channel-bed erodibility underwent large seasonal variations, with mobile sediment present in the channel thalweg during winter that was absent in the spring and summer, when channel-bed erodibility was low and comparable to that of the tidal flats. Sediment on the northern (left) channel flank was mobile in summer and winter, whereas sediment on the southern flank was not. Seasonal changes in channel-bed erodibility are sufficient to produce order-of-magnitude changes in suspended sediment concentrations during peak tidal flows. Porosity just below the sediment surface was the best predictor of erodibility in our study area.

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.

Dual effects of phloretin on aflatoxin B1 metabolism: activation and detoxification of aflatoxin B1.

PubMed

Gao, Shang Shang; Chen, Xiao Yan; Zhu, Ri Zhe; Choi, Byung-Min; Kim, Sun Jun; Kim, Bok-Ryang

2012-01-01

Typically, chemopreventive agents involve either induction of phase II detoxifying enzymes and/or inhibition of cytochrome P450 enzymes (CYPs) that are required for the activation of procarcinogens. In this study, we investigated the protective effects of phloretin against aflatoxin B1 (AFB1) activation to the ultimate carcinogenic intermediate, AFB(1)-8, 9-epoxide (AFBO), and its subsequent detoxification. Phloretin markedly inhibited formation of the epoxide with human liver microsomes in a dose-dependent manner. Phloretin also inhibited the activities of nifedipine oxidation and ethoxyresorufin O-deethylase (EROD) in human liver microsomes. These data show that phloretin strongly inhibits CYP1A2 and CYP3A4 activities, which are involved in the activation of AFB1. Phloretin increased glutathione S-transferase (GST) activity of alpha mouse liver 12 (AML 12) cells in a dose-dependent manner. GST activity toward AFBO in cell lysates treated with 20 μM phloretin was 23-fold that of untreated control cell lysates. The expression of GSTA3, GSTA4, GSTM1, GSTP1 and GSTT1 was induced by phloretin in a dose-dependent manner in AML 12 cells. GSTP1, GSTM1, and GSTT1 were able to significantly increase the conjugation of AFBO with glutathione. Concurrently, induction of the GST isozyme genes was partially associated with the Nrf2/ARE pathway. Taken together, the results demonstrate that phloretin has a strong chemopreventive effect against AFB1 through its inhibitory effect on CYP1A2, CYP3A4, and its inductive effect on GST activity. Copyright © 2012 International Union of Biochemistry and Molecular Biology, Inc.

Impinging Jets and the Erodibility of Cohesive Sediment

NASA Astrophysics Data System (ADS)

Karamigolbaghi, M.; Bennett, S. J.; Ghaneeizad, S. M.; Atkinson, J. F.

2016-12-01

Defining the erodibility of cohesive sediment remains a critical challenge in Earth surface systems. The primary geomorphic law used in such applications relates erosion rate to an erodibility coefficient and an excess shear stress term. To assess erodibility, an inverse modeling approach can be adopted, wherein a known stress is applied to the cohesive sediment, and the erodibility parameters can be deduced through observation of erosion as a function of time. An impinging jet, as used in the jet erosion test, would appear to be an ideal flow (stress) source for erosion assessment. Recent work, however, has demonstrated that jet hydrodynamics can depart significantly from ideal flow conditions when employed for in situ erosion assessment. Here we will review jet theory and the use of jets for assessing the erodibility of cohesive sediment. Our results show that (1) flow confinement and the generation of secondary circulation can significantly change bed shear stress near and downstream of impingement, (2) the evolving scour hole shape, as conditioned by material characteristics and the erosion process, can significantly alter jet hydrodynamics and bed shear stress magnitudes and distributions near and downstream of impingement, and (3) incidental variations in material characteristics in carefully-executed, long-lived experiments can produce markedly different scour hole shapes and derived erodibility indices. Examples from experimental, numerical, and field observations will be used to illustrate these hydrodynamic and material effects on observed and predicted erosion rates. Because such effects are difficult to anticipate, the uncertainty of in situ cohesive sediment assessments using impinging jets can be quite large.

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.

Potential fate of eroded SOC after erosion

NASA Astrophysics Data System (ADS)

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

2015-04-01

Globally, soils contain more than three times as much carbon as either atmosphere or terrestrial vegetation. Soil erosion moves soil organic carbon (SOC) from the site of soil and SOC formation and to depositional environments. There some SOC might be sequestered. Combined with dynamic replacement at the site of erosion, the effect can significantly influence the carbon cycle. However, the fate of SOC moved by erosion has been subject to an intense controversy. Two opposing views prevail: erosion may contribute to SOC mineralization during transport and thus act as a source for atmospheric CO2; the burial of SOC, on the other hand, can be seen as a sink while dynamic replacement maintains SOC at the eroding site and thus increase the C-stocks in soils and sediments. The debate suffers from a lack of information on the distribution, movement and fate of SOC in terrestrial ecosystems. This study aims to improve our understanding of the transport and subsequent fate of the eroded soil and the associated SOC. The research presented here focused on the SOC content and potential transport distance of erode soil. During a series of simulated rainfall soil eroded on crusted loess soils near Basel, Switzerland, was collected. The sediment was fractionated according to its settling velocity, with classes set to correspond to either a transfer into rivers or a deposition on slopes. The soil mass, SOC concentration and cumulative CO2 emission of each fraction were measured. Our results show that about 50% of the eroded sediment and 60% of the eroded SOC are likely to be deposited on the slopes, even during a high rainfall intensity event. This is 3 times greater than the association of SOC with mineral particles suggests. The CO2 emission of the eroded soil is increased by 40% compared to disturbed bulk soil. This confirms that aggregate breakdown reduces the protection of SOC in aggregates. Both results of this study show that taking (i) the effect of aggregation on SOC

Alteration of cytochrome P450 1 regulation and HSP 70 level in brain of juvenile common carp (Cyprinus carpio) after chronic exposure to tributyltin.

PubMed

Li, Zhi-Hua; Zhong, Li-Qiao; Wu, Yan-Hua; Mu, Wei-Na

2016-02-01

Tributyltin (TBT), a toxic contaminant in aquatic environments, has bio-accumulated in aquatic food webs throughout the world and can be found at toxic levels in some biota. However, the molecular mechanisms and effects of TBT are not fully understood. The aim of the present study was to investigate the effect of long-term exposure of TBT on cytochrome P450 (CYP450) 1 regulation and heat-shock proteins (HSPs) profiling in brain of freshwater teleost. The effects of long-term exposure to TBT on mRNA expression of cytochrome P450 (CYP450) 1 family genes and ethoxyresorufin O-deethylase (EROD) activity in the brain of common carp were evaluated, as well as HSP 70 level. Fish were exposed to sublethal concentrations of TBT (75 ng/L, 0.75 μg/L and 7.5 μg/L) for 15, 30, and 60 days. Based on the results, long-term exposure (more than 15 days) to TBT could lead to obvious physiological-biochemical responses (based on EROD activity, HSP 70 level and CYP450 1 family genes expression). The mRNA expression of CYP450 1 family genes (CYP1A, CYP1B, CYP1C1 and CYP1C2) suggested that CYP1A was to accommodate most EROD activity in fish, but other CYP450 forms also involved in this proceeding. Thus, the measured physiological responses in fish brain could provide useful information to better understand the mechanisms of TBT-induced bio-toxicity and could be used as potential biomarkers for monitoring the TBT pollution in the field.

7 CFR 12.22 - Highly erodible field determination criteria.

Code of Federal Regulations, 2014 CFR

2014-01-01

... percent or more of the total field acreage is identified as soil map units which are highly erodible; or (2) 50 or more acres in such field are identified as soil map units which are highly erodible. (b...

7 CFR 12.22 - Highly erodible field determination criteria.

Code of Federal Regulations, 2013 CFR

2013-01-01

... percent or more of the total field acreage is identified as soil map units which are highly erodible; or (2) 50 or more acres in such field are identified as soil map units which are highly erodible. (b...

7 CFR 12.22 - Highly erodible field determination criteria.

Code of Federal Regulations, 2011 CFR

2011-01-01

... percent or more of the total field acreage is identified as soil map units which are highly erodible; or (2) 50 or more acres in such field are identified as soil map units which are highly erodible. (b...

7 CFR 12.22 - Highly erodible field determination criteria.

Code of Federal Regulations, 2012 CFR

2012-01-01

... percent or more of the total field acreage is identified as soil map units which are highly erodible; or (2) 50 or more acres in such field are identified as soil map units which are highly erodible. (b...

Long-term effects of antibiotics, norfloxacin, and sulfamethoxazole, in a partial life-cycle study with zebrafish (Danio rerio): effects on growth, development, and reproduction.

PubMed

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

2016-09-01

A partial life-cycle study with zebrafish (Danio rerio) was conducted to evaluate the long-term effects of antibiotics, norfloxacin (NOR) and sulfamethoxazole (SMX). A series of bio-endpoints correlated to the growth, development, and reproduction was assessed. The results showed that the body weight and the condition factor were depressed by SMX at 200 μg/L during the growth period. Meanwhile, the activities of metabolic enzyme (ethoxyresorufin O-deethylase, EROD) and antioxidant enzymes (superoxide dismutase, SOD and catalase, CAT) were stimulated in all cases. The consequences of parental exposure to antibiotics for the next generation were also examined. The egg production of parents were depressed by the 200 μg/L NOR and SMX alone or in combination. Similarly, decreased hatching, survival, and enhanced development abnormality of the next generation also occurred after parental exposure to SMX at the highest concentration. The heartbeat however was not altered in all cases. Furthermore, there was no significant difference in the bio-endpoints between the combined and individual treatment in most cases, with the exception of lower EROD activity and egg production in the co-treatment. The results suggest that long-term exposure to NOR and SMX at environmentally relevant concentrations, individually and in a mixture, may not significantly pose a threat to the growth, development, and reproduction of zebrafish, and an adverse effect may be expected at high concentration.

Biomarkers of Contaminant Exposure in Chub (Leuciscus cephalus L.) – Biomonitoring of Major Rivers in the Czech Republic

PubMed Central

Havelkova, Marcela; Blahova, Jana; Kroupova, Hana; Randak, Tomas; Slatinska, Iveta; Leontovycova, Drahomira; Grabic, Roman; Pospisil, Richard; Svobodova, Zdenka

2008-01-01

Biochemical analysis of organisms to assess exposure to environmental contaminants is of great potential use. Biochemical markers, specifically liver enzymes of the first and the second phase of xenobiotic transformation - cytochrome P450 (CYP 450), ethoxyresorufin-O-deethylase (EROD), glutathione-S-transferase (GST) and tripeptide reduced glutathione (GSH) - were used to assess contamination of the aquatic environment at 12 locations near the mouths of major rivers in the Czech Republic. These rivers were the Lužnice, Otava, Sázava, Berounka, Vltava, Labe, Ohře, Svratka, Dyje, Morava and Odra. The indicator species selected was the Chub (Leuciscus cephalus L.). The highest levels of CYP 450 and EROD catalytic activity were found in livers of fish from the Labe (Obříství; (0.32±0.10 nmol mg−1 protein and 1061.38±545.51 pmol min−1 mg−1 protein, respectively). The highest levels of GST catalytic activity and GSH content were found in fish from the Otava (35.39±13.35 nmol min−1 mg−1 protein and 4.29±2.10 nmol GSH mg−1 protein, respectively). They were compared with levels of specific inductors of these biochemical markers in muscle. The results confirmed contamination of some river locations (Labe Obříství, Svratka;. PMID:27879837

Advancing Understanding of Earthquakes by Drilling an Eroding Convergent Margin

NASA Astrophysics Data System (ADS)

von Huene, R.; Vannucchi, P.; Ranero, C. R.

2010-12-01

perhaps geologically than the Nankai margin. The developing Central American countries do not have the resources to contribute to IODP but this should not deter acquiring the scientific insights proposed in CRISP considering the broader scientific benefits. Such benefits include the first sampling and instrumentation of an actively eroding plate interface and drilling near or into an earthquake asperity. Drilling an eroding margin should significantly advance understanding of subduction zone fault mechanisms and help improve assessment of future hazardous earthquakes and tsunamis.

Chemical and toxicological characterizations of hydraulic fracturing flowback and produced water.

PubMed

He, Yuhe; Flynn, Shannon L; Folkerts, Erik J; Zhang, Yifeng; Ruan, Dongliang; Alessi, Daniel S; Martin, Jonathan W; Goss, Greg G

2017-05-01

Hydraulic fracturing (HF) has emerged as a major method of unconventional oil and gas recovery. The toxicity of hydraulic fracturing flowback and produced water (HF-FPW) has not been previously reported and is complicated by the combined complexity of organic and inorganic constituents in HF fluids and deep formation water. In this study, we characterized the solids, salts, and organic signatures in an HF-FPW sample from the Duvernay Formation, Alberta, Canada. Untargeted HPLC-Orbitrap revealed numerous unknown dissolved polar organics. Among the most prominent peaks, a substituted tri-phenyl phosphate was identified which is likely an oxidation product of a common polymer antioxidant. Acute toxicity of zebrafish embryo was attributable to high salinity and organic contaminants in HF-FPW with LC50 values ranging from 0.6% to 3.9%, depending on the HF-FPW fractions and embryo developmental stages. Induction of ethoxyresorufin-O-deethylase (EROD) activity was detected, due in part to polycyclic aromatic hydrocarbons (PAHs), and suspended solids might have a synergistic effect on EROD induction. This study demonstrates that toxicological profiling of real HF-FPW sample presents great challenges for assessing the potential risks and impacts posed by HF-FPW spills. Copyright © 2017 Elsevier Ltd. All rights reserved.

Increased formation of carcinogenic PAH metabolites in fish promoted by nitrite.

PubMed

Shailaja, M S; Rajamanickam, Rani; Wahidulla, Solimabi

2006-09-01

Nitrite (NO(2)(-)), a highly reactive chemical species, accumulates in coastal waters as a result of pollution with nitrogenous waste and/or an imbalance in the bacterial processes of nitrification and denitrification. The present study probed the impact of nitrite (NO(2)(-)) on the metabolism of polycyclic aromatic hydrocarbons (PAHs) in fish. In a laboratory experiment, exposure of euryhaline fish, Oreochromis mossambicus to industrial effluents containing PAHs in the presence of NO(2)(-) enhanced the cytochrome P450-dependent biotransformation activity determined as 7-ethoxyresorufin-O-deethylase (EROD), by nearly 36% compared to the value observed in the absence of NO(2)(-) (50.2 +/- 6.74 pmol resorufin min(-1) g(-1) liver). Fixed wavelength fluorescence measurements in bile revealed maximum enhancement to have occurred in the metabolites of benzo[a]pyrene, a carcinogenic PAH. Lasting, sublethal physiological deterioration was apparent in fish exposed simultaneously to an oil refinery effluent and NO(2)(-), from the unremittingly decreasing liver somatic index, even after the withdrawal of the contaminants.

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.

An early approach for the evaluation of repair processes in fish after exposure to sediment contaminated by an oil spill.

PubMed

Salamanca, Maria J; Jimenez-Tenorio, Natalia; Reguera, Diana F; Morales-Caselles, Carmen; Delvalls, T Angel

2008-12-01

A chronic bioassay was carried out under laboratory conditions using juvenile Solea senegalensis to determine the toxicity of contaminants from an oil spill(Prestige). Also, the repair processes in fish affected by contaminants due to oil exposure were evaluated. Over 30 days individuals were exposed to clean sediment (control) and to sediment contaminated by a mixture of polyaromatic hydrocarbons (PAHs) and other substances. The physicochemical parameters of the tanks (salinity, temperature, pH and dissolved oxygen) were controlled during the exposure period. Clean sediment from the Bay of Cadiz (Spain) was used as negative control and was mixed with fuel oil to prepare the dilution (0.5% w:w dry-weight). After the exposure period, fish were labeled and transferred to "clean tanks" (tanks without sediment) in order to study the recovery and the repair processes in the exposed organisms. A biomarker of exposure (ethoxyresorufin-O-deethylase activity - EROD activity) and a biomarker of effect (histopathology) were analyzed during the exposure and recovery period. After 10, 20 and 30 days of exposure, individuals showed significant induction (P < 0.05) of the EROD activity and also presented diverse histopathological damages. The analysis of both the biomarkers of exposure and effect, after the 5th and 10th day of recovery in the "clean tank", enabled a first evaluation of the repair process of the induced damages due to the fuel oil exposure. After the recovery phase, control individuals showed a more significant decrease (P < 0.05) of the alteration of the measured biomarkers than in the oil-exposed fish. While in the oil-exposed fish the EROD activity showed some recovery, the histopathological damages did hardly improve. According to our results, tissue repair processes probably need longer recovery periods to observe significant improvement of the affected organs. This will be further investigated in the future.

Use of biomarkers in Nile tilapia (Oreochromis niloticus) to assess the impacts of pollution in Bolgoda Lake, an urban water body in Sri Lanka.

PubMed

Pathiratne, A; Chandrasekera, L W H U; Pathiratne, K A S

2009-09-01

The present study reports the first analysis of water pollutants in Sri Lankan waters using a suite of biomarkers in Nile tilapia (Oreochromis niloticus) residing in Bolgoda Lake which receives urban, industrial and domestic wastes from multiple sources. The fish were collected from the lake in the dry period (April 2005) and wet periods (September 2005, October 2006) and the levels of biomarkers viz. hepatic ethoxyresorufin O-deethylase (EROD), glutathione S-transferase (GST), metallothioneins, biliary fluorescent aromatic compounds, brain and muscle cholinesterases (ChE) were compared with those of the laboratory reared control fish and the fish obtained from a less polluted water body, Bathalagoda reservoir (reference site). The results revealed that biomarker levels of the fish collected from the reference site were not significantly different from the controls. Hepatic EROD and GST activities in fish from Bolgoda Lake were induced 4.2-16.6 folds and 1.4-3.3 folds respectively compared with the control fish. Analysis of bile in the lake fish revealed recent uptake of naphthalene, pyrene and benzo(a)pyrene type polycyclic aromatic hydrocarbons (PAHs). The induction of EROD activities in feral fish reflects the exposure of fish to aryl hydrocarbon receptor agonists including PAHs present as pollutants in the Bolgoda Lake. Cholinesterase activity in the fish inhabiting one sampling site of Bolgoda Lake was lower (22-40% inhibition) than the activity measured in the control fish indicating the presence of anticholinesterase pollutants in the area. Hepatic metallothionein levels in the lake fish were higher (1.9-3.2 folds) in comparison to the controls indicating metal exposure. The results support the potential use of these biomarkers in Nile tilapia in assessing pollution in tropical water bodies.

Linking Ah receptor mediated effects of sediments and impacts on fish to key pollutants in the Yangtze Three Gorges Reservoir, China - A comprehensive perspective.

PubMed

Floehr, Tilman; Scholz-Starke, Björn; Xiao, Hongxia; Hercht, Hendrik; Wu, Lingling; Hou, Junli; Schmidt-Posthaus, Heike; Segner, Helmut; Kammann, Ulrike; Yuan, Xingzhong; Roß-Nickoll, Martina; Schäffer, Andreas; Hollert, Henner

2015-12-15

The Three Gorges Reservoir (TGR), created in consequence of the Yangtze River's impoundment by the Three Gorges Dam, faces numerous anthropogenic impacts that challenge its unique ecosystem. Organic pollutants, particularly aryl hydrocarbon receptor (AhR) agonists, have been widely detected in the Yangtze River, but only little research was yet done on AhR-mediated activities. Hence, in order to assess effects of organic pollution, with particular focus on AhR-mediated activities, several sites in the TGR area were examined applying the "triad approach". It combines chemical analysis, in vitro, in vivo and in situ investigations to a holistic assessment. Sediments and the benthic fish species Pelteobagrus vachellii were sampled in 2011/2012, respectively, to identify relevant endpoints. Sediment was tested in vitro with the ethoxyresorufin-O-deethylase (EROD) induction assay, and in vivo with the Fish Embryo Toxicity Test and Sediment Contact Assay with Danio rerio. Activities of phase I (EROD) and phase II (glutathione-S-transferase) biotransformation enzymes, pollutant metabolites and histopathological alterations were studied in situ in P. vachellii. EROD induction was tested in vitro and in situ to evaluate possible relationships. Two sites, near Chongqing and Kaixian city, were identified as regional hot-spots and further investigated in 2013. The sediments induced in the in vitro/in vivo bioassays AhR-mediated activities and embryotoxic/teratogenic effects - particularly on the cardiovascular system. These endpoints could be significantly correlated to each other and respective chemical data. However, particle-bound pollutants showed only low bioavailability. The in situ investigations suggested a rather poor condition of P. vachellii, with histopathological alterations in liver and excretory kidney. Fish from Chongqing city exhibited significant hepatic EROD induction and obvious parasitic infestations. The polycyclic aromatic hydrocarbon (PAH) metabolite 1

Reproductive success, developmental anomalies and environmental contaminants in double-crested cormorants (Phalacrocorax auritus)

USGS Publications Warehouse

Larson, J.M.; Karasov, W.H.; Sileo, L.; Stromborg, K.L.; Hanbidge, B.A.; Giesy, J.P.; Jones, P.D.; Tillitt, D.E.; Verbrugge, D.A.

1996-01-01

To test an association between environmental contaminants and the prevalence of congenital anomalies in colonial waterbirds, we collected representative eggs for chemical analysis from double-crested cormorant nests at colonies in Lake Michigan, Wisconsin, USA, and Lake Winnipegosis, Manitoba, Canada, and periodically revisited the nests to determine the hatching success, survivorship of hatchlings, and number of deformed hatchlings in the remainder of each clutch. Total concentrations of polychlorinated biphenyls (PCBs) in eggs were determined by capillary gas chromatography. The combined activity of planar chlorinated hydrocarbons (PCHs) in the eggs was measured in an in vitro bioassay based on the induction of ethoxyresorufin-O-deethylase (EROD) activity in rat hepatoma cells. The combined EROD induction activity was expressed as 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents (TCDD-EQ). Total concentrations of PCBs and TCDD-EQ were seven to eight times greater in eggs from Lake Michigan (7.8 μg/g and 138 pg/g, respectively) than in those from Lake Winnipegosis (1.0 μg/g and 19 pg/g, respectively). The proportion of eggs hatching at the Lake Michigan colony (59%) was less (p < 0.05) than at Lake Winnipegosis (70%), and the prevalence of hatchlings with deformed bills was greater (p < 0.001) at Lake Michigan (0.79 vs. 0.06%). However, within the Lake Michigan colony, concentrations of PCBs and TCDD-EQ were not correlated with either hatching success or the occurrence of deformities in nestlings.

Assessment of biological effects of pollutants in a hyper eutrophic tropical water body, Lake Beira, Sri Lanka using multiple biomarker responses of resident fish, Nile tilapia (Oreochromis niloticus).

PubMed

Pathiratne, Asoka; Pathiratne, K A S; De Seram, P K C

2010-08-01

Biomarkers measured at the molecular and cellular level in fish have been proposed as sensitive "early warning" tools for biological effect measurements in environmental quality assessments. Lake Beira is a hypertrophic urban water body with a complex mixture of pollutants including polycyclic aromatic hydrocarbons (PAHs) and Microcystins. In this study, a suite of biomarker responses viz. biliary fluorescent aromatic compounds (FACs), hepatic ethoxyresorufin O-deethylase (EROD) and glutathione S-transferase (GST), brain and muscle cholinesterases (ChE), serum sorbitol dehydrogenase (SDH), and liver histology of Oreochromis niloticus, the dominant fish inhabiting this tropical Lake were evaluated to assess the pollution exposure and biological effects. Some fish sampled in the dry periods demonstrated prominent structural abnormalities in the liver and concomitant increase in serum SDH and reduction in hepatic GST activities in comparison to the control fish and the fish sampled in the rainy periods. The resident fish with apparently normal liver demonstrated induction of hepatic EROD and GST activities and increase in biliary FACs irrespective of the sampling period indicating bioavailability of PAHs. Muscle ChE activities of the resident fish were depressed significantly indicating exposure to anticholinesterase substances. The results revealed that fish populations residing in this Lake is under threat due to the pollution stress. Hepatic abnormalities in the fish may be mainly associated with the pollution stress due to recurrent exposure to PAHs and toxigenic Microcystis blooms in the Lake.

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.

Cytochrome P450 1A expression in midwater fishes: Potential effects of chemical contaminants in remote oceanic zones

USGS Publications Warehouse

Stegeman, John J.; Schlezinger, Jennifer J.; Craddock, James E.; Tillitt, Donald E.

2001-01-01

Cytochrome P450 1A (CYP1A) induction is a robust marker for exposure to polynuclear aromatic hydrocarbons and planar halogenated aromatic hydrocarbons that are aryl hydrocarbon receptor agonists. We examined CYP1A expression in mesopelagic fishes from the western North Atlantic. Individuals in 22 species were obtained from slope water and the Sargasso Sea in 1977, 1978, and 1993. Aryl hydrocarbon hydroxylase (AHH), a CYP1A activity, was detected in liver from all species in 1977/78. In some, including Gonostoma elongatum, AHH was inhibited by the CYP1A inhibitor ??-naphthoflavone. CYP1A-dependent ethoxyresorufin O-deethylase (EROD) was detected in liver microsomes of all species in 1993; rates were highest in G. elongatum and Argyropelecus aculeatus. Immunoblot analysis with the CYP1A-specific monoclonal antibody 1-12-3 detected a single microsomal protein band in most 1993 samples; the highest content was in G. elongatum. Immunohistochemical analysis showed CYP1A staining in gill, heart, kidney, and/or liver of several species. Extracts of the 1993 G. elongatum and A. aculeatus, when applied to fish hepatoma cells (PLHC-1) in culture, elicited a significant induction of EROD in those cells. The capacity of the extracts to induce CYP1A correlated with the content of PCBs measured in the same fish (2-4.6 ng/g total body weight). Mesopelagic fish in the western North Atlantic, which experience no direct exposure to surface waters or sediments, are exposed chronically to inducers of CYP1A at levels that appear to be biochemically active in those fish.Cytochrome P450 1A (CYP1A) induction is a robust marker for exposure to polynuclear aromatic hydrocarbons and planar halogenated aromatic hydrocarbons that are awl hydrocarbon receptor agonists. We examined CYP1A expression in mesopelagic fishes from the western North Atlantic. Individuals in 22 species were obtained from slope water and the Sargasso Sea in 1977, 1978, and 1993. Aryl hydrocarbon hydroxylase (AHH), a CYP1A

Morphodynamic modeling of erodible laminar channels.

PubMed

Devauchelle, Olivier; Josserand, Christophe; Lagrée, Pierre-Yves; Zaleski, Stéphane

2007-11-01

A two-dimensional model for the erosion generated by viscous free-surface flows, based on the shallow-water equations and the lubrication approximation, is presented. It has a family of self-similar solutions for straight erodible channels, with an aspect ratio that increases in time. It is also shown, through a simplified stability analysis, that a laminar river can generate various bar instabilities very similar to those observed in natural rivers. This theoretical similarity reflects the meandering and braiding tendencies of laminar rivers indicated by F. Métivier and P. Meunier [J. Hydrol. 27, 22 (2003)]. Finally, we propose a simple scenario for the transition between patterns observed in experimental erodible channels.

In vitro cellular responses in the RTG-2 cell line to complex mixtures of dioxins and dioxin-like PCDDs, PCDFs and PCBs.

PubMed

Babín, María del Mar; Sanz, Paloma; Concejero, Miguel Angel; Martínez, María Angeles; Tarazona, José Vicente

2010-08-01

High-resolution gas chromatography/mass spectrometry (HRGC/MS) is the standard method for analysing dioxin, furan and polybrominated retardants in hazardous waste. Determination of dioxin-like compounds using in vitro bioassays such as ethoxyresorufin-O-deethylase (EROD) is an important tool to evaluate their Ah receptor-mediated toxic effects, because it detects all arylhydrocarbon receptor ligands in a variety of sample matrices. In the present work, we compared RTG-2 cell line EROD bioassay with HRGC/MS for assessing waste samples (liquid and solid) contaminated with polychlorinated dibenzo-p-dioxins and dibenzofurans, polychlorinated biphenyls (dioxin-like PCBs) and other xenobiotics. For liquid samples, HRGC/MS-toxic equivalent (HRGC/MS-TEQ) values ranged from 273.26 to 5.84 ng TEQ l(-1) and correlated well (correlation coefficient 0.99) with values obtained by EROD-TEQ, which ranged from 128 to 2.5 ng TEQ l(-1). For solid samples, HRGC/MS-TEQ values ranged from 3.44 to 0.49 ng TEQ g(-1) and correlated less well than liquid samples (correlation coefficient 0.64) with values obtained by EROD-TEQ ranging from 2.27 to 0.93 ng TEQ g(-1). The overestimation of RTG-2 EROD-TEQ (1.2 +/- 0.92 of values established by HRGC/MS) and the absence of false-negative results may limit analytical costs by eliminating the need for follow-up GC/MS analysis on the negative samples. We suggest that RTG-2 EROD bioassay is an inexpensive means for preliminary dioxin and furan positive screenings of waste samples. (c) 2010 John Wiley & Sons, Ltd.

Tributyltin modulates 3,3',4,4',5-pentachlorobiphenyl (PCB-126)-induced hepatic CYP1A activity in channel catfish, Ictalurus punctatus.

PubMed

Rice, C D; Roszell, L E

1998-10-09

Many harbor estuaries and their tributaries are contaminated with halogenated aromatic hydrocarbons (HAHs) and polycyclic aromatic hydrocarbons (PAHs). Planar congeners of these two classes initiate their toxic effects, including reproductive, developmental, and immunological dysfunction, primarily through the cytosolic arylhydrocabon receptor (Ahr). However, only rarely are aquatic environments contaminated with Ahr-binding contaminants alone. Instead, most are impacted by a variety of pollutants in mixture. Tributyltin (TBT), a common antifouling biocide, is also found in many harbor estuaries and their tributaries. Several reports indicate that TBT inhibits the cytochrome P-4501A system of fish, at least in vitro, and our recent studies with rodents indicate that TBT potentiates PCB-induced CYP1A. However, the effects of TBT on xenobiotic-induced CYP1A activity in aquatic organisms has been virtually unexplored. To this end, channel catfish, Ictalurus punctatus, were exposed to 3,3'4,4',5-pentachlorobiphenyl (PCB-126, PeCB), TBT, or both in combination, with corn oil (CO) serving as the carrier control. Immunoreactive CYP1A protein and ethoxyresorufin O-deethylase (EROD) activity were measured after (1) a single dose of 0.01, 0. 1, or 1 mg/kg of each or both in combination, and (2) 6 injections of 0.017, 1.7, or 17 microg/kg of each (or in combination) given every 3 d over a 16-d period to yield a cumulative dose of 0.01, 0.1, or 1 mg/kg. As expected, PeCB alone, but not TBT, greatly induced these two CYP1A parameters. Low and middle doses of TBT (0.01 and 0.1 mg/kg), but not the high dose, potentiated PeCB-induced activity at these same doses. This effect of TBT was even more pronounced in the repeated exposure study. Furthermore, EROD activity did not always reflect CYP1A protein induction; enzyme activity was inhibited by TBT at doses that potentiated protein induction (0.01 and 0.1 mg/kg). In summary, TBT potentiates PeCB-induced CYP1A in channel catfish at

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

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

Johri, Ashu; Yadav, Sanjay; Dhawan, Alok

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 ofmore » 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.« less

Simulating eroded soil organic carbon with the SWAT-C model

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

Zhang, Xuesong

The soil erosion and associated lateral movement of eroded carbon (C) have been identified as a possible mechanism explaining the elusive terrestrial C sink of ca. 1.7-2.6 PgC yr(-1). Here we evaluated the SWAT-C model for simulating long-term soil erosion and associated eroded C yields. Our method couples the CENTURY carbon cycling processes with a Modified Universal Soil Loss Equation (MUSLE) to estimate C losses associated with soil erosion. The results show that SWAT-C is able to simulate well long-term average eroded C yields, as well as correctly estimate the relative magnitude of eroded C yields by crop rotations. Wemore » also evaluated three methods of calculating C enrichment ratio in mobilized sediments, and found that errors associated with enrichment ratio estimation represent a significant uncertainty in SWAT-C simulations. Furthermore, we discussed limitations and future development directions for SWAT-C to advance C cycling modeling and assessment.« less

Effects of the brominated flame retardants hexabromocyclododecane (HBCDD), and tetrabromobisphenol A (TBBPA), on hepatic enzymes and other biomarkers in juvenile rainbow trout and feral eelpout.

PubMed

Ronisz, D; Finne, E Farmen; Karlsson, H; Förlin, L

2004-08-25

Brominated flame retardants (BFRs) leak out in the environment, including the aquatic one. Despite this, sublethal effects of these chemicals are poorly investigated in fish. In this study, a screening of selected biomarkers in juvenile rainbow trout (Oncorhynchus mykiss) and feral eelpout (Zoarces viviparus) was performed after exposure to hexabromocyclododecane (HBCDD) and tetrabromobisphenol A (TBBPA). Rainbow trout was injected intraperitoneally (i.p.) with HBCDD or TBBPA. Two out of four short-term experiments with HBCDD showed an increase in the activity of catalase. A 40% increase in liver somatic index (LSI) could be observed after 28 days. HBCDD did also seem to have an inhibitory effect on CYP1A's activity (ethoxyresorufin-O-deethylase (EROD)). A putative peroxisome proliferating activity of the compound was investigated without giving a definite answer. HBCDD did not seem to be estrogenic or genotoxic. TBBPA increased the activity of glutathione reductase (GR) after 4, 14 and 28 days in rainbow trout suggesting a possible role of this compound in inducing oxidative stress. The compound did not seem to be estrogenic. TBBPA seemed to compete with the artificial substrate ethoxyresorufin in vitro, during the EROD assay. In eelpout, only one 5 days in vivo experiment was performed. Neither of the compounds gave rise to any effect in this fish. This was the first screening of sublethal effects of the two chemicals in fish, using high doses. Our results indicate that there is a need for further studies of long-term, low-dose effects of these two widely used flame retardants.

Toxicity of analytically cleaned pentabromodiphenylether after prolonged exposure in estuarine European flounder (Platichthys flesus), and partial life-cycle exposure in fresh water zebrafish (Danio rerio).

PubMed

Kuiper, Raoul V; Vethaak, A D; Cantón, Roćio F; Anselmo, Henrique; Dubbeldam, Marco; van den Brandhof, Evert-Jan; Leonards, Pim E G; Wester, Piet W; van den Berg, Martin

2008-09-01

Residues of polybrominated diphenylethers (PBDEs), extensively applied as flame retardants, are widely spread in the aquatic environment and biota. The present study investigates effects of the environmentally relevant lower brominated diphenylethers in two fish species in vivo under controlled laboratory conditions. Euryhaline flounder (Platichthys flesus) and freshwater zebrafish (Danio rerio) were exposed to a range of concentrations of a commercial pentabromodiphenylether mixture, DE-71. Chemical analysis of exposed fish showed a pattern of PBDE congeners that was very similar to that in wild fish. The resulting range included environmentally relevant, as well as higher levels. Animals were investigated histopathologically with emphasis on endocrine and reproductive organs. In zebrafish, hatching of embryos and larval development were assessed. Biochemical parameters were investigated in flounder as markers for suggested dioxin-like activity (ethoxyresorufin-O-deethylase=EROD), and activation of endogenous estrogen synthesis (gonad aromatase activity). Thyroid hormones were analyzed in plasma in both species. Benchmark analysis using internal PBDE concentrations showed a mild dose-dependent decrease of hepatic EROD and ovarian aromatase activities, and plasma thyroxin levels in flounder, and an increase of plasma thyroid hormone levels in zebrafish. These trends did not result in statistically significant differences from control fish, and major histopathological changes were not observed. Reproduction in zebrafish appeared to be the most sensitive parameter with statistically significantly reduced larval survival and non-significant indications for decreased egg production at internal levels that were more than 55 times the highest environmental recordings. The present results indicate limited risk for endocrine or reproductive effects of current environmental PBDE contamination in fish.

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. Copyright © 2014. Published by Elsevier B.V.

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

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

Brunstroem, B.

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 commonmore » 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.« less

Societal Forces That ERODE Creativity

ERIC Educational Resources Information Center

Sternberg, Robert; Kaufman, James C.

2018-01-01

Background/Context: Creativity is an indispensable force in intellectual, social, cultural, and economic development. Yet societal forces conspire to erode it. Educators have despaired for many years over how schools often fail to encourage creativity, but society as a whole is just as guilty. But how do schools and society fail to encourage, or…

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…

Modeling changes in rill erodibility and critical shear stress on native surface roads

Treesearch

Randy B. Foltz; Hakjun Rhee; William J. Elliot

2008-01-01

This study investigated the effect of cumulative overland flow on rill erodibility and critical shear stress on native surface roads in central Idaho. Rill erodibility decreased exponentially with increasing cumulative overland flow depth; however, critical shear stress did not change. The study demonstrated that road erodibility on the studied road changes over the...

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.

Morphology of ductile metals eroded by a jet of spherical particles impinging at normal incidence

NASA Technical Reports Server (NTRS)

Veerabhadra Rao, P.; Young, S. G.; Buckley, D. H.

1983-01-01

Scanning electron microscopy and energy-dispersive X-ray spectroscopy are used, together with surface profile measurements, in the present morphological study of the erosion of an aluminum alloy and copper by the normal impact of spherical glass erodent particles. The morphology of the damage pattern is a manifestation of the flow pattern of erodent particles, and yields insight into the mechanisms that may be active at different stages of erosion. The simultaneous appearance of radial cracks and concentric rings is reported, together with wave crests which contain an accumulation of metallic flakes. A preliminary analysis is advanced to explain the formation of the various damage patterns observed.

Elastic wave generated by granular impact on rough and erodible surfaces

NASA Astrophysics Data System (ADS)

Bachelet, Vincent; Mangeney, Anne; de Rosny, Julien; Toussaint, Renaud; Farin, Maxime

2018-01-01

The elastic waves generated by impactors hitting rough and erodible surfaces are studied. For this purpose, beads of variable materials, diameters, and velocities are dropped on (i) a smooth PMMA plate, (ii) stuck glass beads on the PMMA plate to create roughness, and (iii) the rough plate covered with layers of free particles to investigate erodible beds. The Hertz model validity to describe impacts on a smooth surface is confirmed. For rough and erodible surfaces, an empirical scaling law that relates the elastic energy to the radius Rb and normal velocity Vz of the impactor is deduced from experimental data. In addition, the radiated elastic energy is found to decrease exponentially with respect to the bed thickness. Lastly, we show that the variability of the elastic energy among shocks increases from some percents to 70% between smooth and erodible surfaces. This work is a first step to better quantify seismic emissions of rock impacts in natural environment, in particular on unconsolidated soils.

Soil aggregation, erodibility, and erosion rates in mountain soils (NW Alps, Italy)

NASA Astrophysics Data System (ADS)

Stanchi, S.; Falsone, G.; Bonifacio, E.

2015-04-01

Erosion is a relevant soil degradation factor in mountain agrosilvopastoral ecosystems that can be enhanced by the abandonment of agricultural land and pastures left to natural evolution. The on-site and off-site consequences of soil erosion at the catchment and landscape scale are particularly relevant and may affect settlements at the interface with mountain ecosystems. RUSLE (Revised Universal Soil Loss Equation) estimates of soil erosion consider, among others, the soil erodibility factor (K), which depends on properties involved in structure and aggregation. A relationship between soil erodibility and aggregation should therefore be expected. However, erosion may limit the development of soil structure; hence aggregates should not only be related to erodibility but also partially mirror soil erosion rates. The aim of the research was to evaluate the agreement between aggregate stability and erosion-related variables and to discuss the possible reasons for discrepancies in the two kinds of land use considered (forest and pasture). Topsoil horizons were sampled in a mountain catchment under two vegetation covers (pasture vs. forest) and analyzed for total organic carbon, total extractable carbon, pH, and texture. Soil erodibility was computed, RUSLE erosion rate was estimated, and aggregate stability was determined by wet sieving. Aggregation and RUSLE-related parameters for the two vegetation covers were investigated through statistical tests such as ANOVA, correlation, and regression. Soil erodibility was in agreement with the aggregate stability parameters; i.e., the most erodible soils in terms of K values also displayed weaker aggregation. Despite this general observation, when estimating K from aggregate losses the ANOVA conducted on the regression residuals showed land-use-dependent trends (negative average residuals for forest soils, positive for pastures). Therefore, soil aggregation seemed to mirror the actual topsoil conditions better than soil

Screening of Enzyme Biomarker for Nanotoxicity of Zinc Oxide in OREOCHROMIS MOSSAMBICUS

NASA Astrophysics Data System (ADS)

Subramanian, Periasamy; Bupesh, Giridharan

2011-06-01

Experiments were conducted to determine the effects of Zinc oxide (ZnO) nanoparticles (NPs) on fish models. Oreochromis mossambicus was orally administered with ZnO NPs (50-100 nm) once and its effects at five different concentrations (60 ppm-100 ppm) were observed for 12 days. Enzymatic assays were performed at every three days interval in the vital tissues of liver, gill, muscle and kidney. The defense enzymes, ethoxyresorufin O-deethylase (EROD) and glutathione S transferase (GST) exerted a dose dependent elevation up to 6 days. This hike then declines in higher concentrations and extended duration. Whereas the tissue damaging enzymes, glutamate oxaloacetic transaminase (GOT), glutamate pyruvic transaminase (GPT) and alkaline phosphatase (ALP) as well as the antioxidant enzymes superoxide dismutase (SOD), catalase (CAT) exhibited a dose and duration dependent increase until the end of the experiment. Among these enzymes, the antioxidant enzymes response to ZnO NP toxicity on fish showed notable continuous induction. This study demonstrates that antioxidant enzymes responses in O. mossambicus could be used as a biomarker for the early detection of nanotoxicity.

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

In vivo/in vitro comparison of pharmacokinetics and pharmacodynamics of 3,3',4,4'-tetrachlorobiphenyl (PCB77)

USGS Publications Warehouse

Yu, Kyung O.; Tillitt, Donald E.; Byczkowski, Janusz Z.; Burton, G. Allen; Channel, Stephen R.; Drerup, Joanne M.; Flemming, Carlyle D.; Fisher, Jeffrey W.

1996-01-01

The rat hepatoma cell line, H4IIE, serves as a useful tool to assess potential biological effects such as induction of cytochrome P4501A1 expression. The objectives of this study were twofold: to investigate the kinetic time course and dosimetry of PCB77 in rat hepatoma cells dosed with PCB77 and in liver of rats given ip doses of PCB77, and to comparein vitroandin vivoP4501A1 enzyme induction responses. For the 4-day time–course study, H4IIE cells were exposed with two doses of [14C]PCB77 (0.9 and 3 μg/plate) and harvested at 15 and 30 min, 1, 2, 4, 8, and 12 hr, and 1, 2, 3, and 4 days. PCB77-derived radioactivity was detected in the cells as early as 15 min postdosing. For the dose–response study, the cells were dosed with various concentrations of PCB77 (0.00316–5.37 μg/plate) and harvested on Day 3 since ethoxyresorufinO-deethylase (EROD) activityin vitroreached its maximum on the third day postdosing. Time–course and dose–response studies revealed that only 1–3% of the total delivered dose was found in the cells, with the remainder in the media and adhering to the culture plates. For the dose–response studyin vivo,male Fischer rats were dosed with a single ip injection of various concentrations of PCB77 (0.1–50 mg/kg body wt) and euthanized on Day 3. PCB77-derived radioactivity and EROD inductionin vivowere measured. When EROD activity and PCB77-derived radioactivity in the rat hepatoma cells and in the rat liver were compared on an equivalent weight basis, there was a significant correlation (r2= 0.985) between them. Prior to this study, no information on quantitative dosimetry and EROD activities of PCB77 has been reported to validate thein vitroassay within vivodata.

[Spatiotemporal variation of typical red soil eroded landscape pattern: a case study in Changting County of Fujian Province].

PubMed

Wu, Guo-sheng; Lin, Hui-hua; Zhu, He-jian; Sha, Jin-ming; Dai, Wen-yuan

2011-07-01

Based on the 1988, 2000, and 2007 remote sensing images of a typical red soil eroded region (Changting County, Fujian Province) and the digital elevation model (DEM), the eroded landscape types were worked out, and the changes of the eroded landscape pattern in the region from 1988 to 2007 were analyzed with the spatial mathematics model. In 1988-2007, different eroded landscape types in the region had the characteristics of inter-transfer, mainly manifested in the transfer from seriously eroded to lightly eroded types but still existed small amount of the transference from lightly eroded to seriously eroded types. Little change was observed in the controid of the eroded landscape. In the County, Hetian Town was all along the eroded center. During the study period, the landscape pattern index showed a tendency of low heterogeneity, low fragmentation, and high regularization at landscape level, but an overall improvement and expansion of lightly eroded and easy-to-tackle patches as well as the partial improvement and fragmentation of seriously eroded and difficult-to-tackle patches at patch level.

Textural characteristics and sedimentary environment of sediment at eroded and deposited regions in the severely eroded coastline of Batu Pahat, Malaysia.

PubMed

Wan Mohtar, Wan Hanna Melini; Nawang, Siti Aminah Bassa; Abdul Maulud, Khairul Nizam; Benson, Yannie Anak; Azhary, Wan Ahmad Hafiz Wan Mohamed

2017-11-15

This study investigates the textural characteristics of sediments collected at eroded and deposited areas of highly severed eroded coastline of Batu Pahat, Malaysia. Samples were taken from systematically selected 23 locations along the 67km stretch of coastline and are extended to the fluvial sediments of the main river of Batu Pahat. Grain size distribution analysis was conducted to identify its textural characteristics and associated sedimentary transport behaviours. Sediments obtained along the coastline were fine-grained material with averaged mean size of 7.25 ϕ, poorly sorted, positively skewed and has wide distributions. Samples from eroded and deposition regions displayed no distinctive characteristics and exhibited similar profiles. The high energy condition transported the sediments as suspension, mostly as pelagic and the sediments were deposited as shallow marine and agitated deposits. The fluvial sediments of up to 3km into the river have particularly similar profile of textural characteristics with the neighbouring marine sediments from the river mouth. Profiles were similar with marine sediments about 3km opposite the main current and can go up to 10km along the current of Malacca Straits. Copyright © 2017 Elsevier B.V. All rights reserved.

Estimating eroded soil and predicting further erosion in Daisetsuzan National Park in Hokkaido, Japan

NASA Astrophysics Data System (ADS)

Kobayashi, Yusuke; Watanabe, Teiji

2017-04-01

This study has three objectives: (1) to estimate changes of the eroded volume of mountain trails from 2014 to 2016 by making DSMs, (2) to understand a relationship between the trail erosion and micro-topography, and (3) to predict the volume of soil that can be eroded in future. Trail erosion has been investigated near Mt. Hokkai-dake in Daisetzuzan National Park, Hokkaido, northern Japan, with a drone (UAV) from 2014 to 2016. Seven segments with the soil erosion from starting sites to ending sites were selected to make DSMs and Orthophotographs by Agisoft, which is one of the Structure from Motion (SfM) software. Then, at fourteen points in each of the seven segments were selected to estimate the volume of soil that can be eroded in the future by PANDA2, a soil compaction penetrometer. The eroded volume in the segment with the largest eroded value attained 274.67 m3 for the two-year period although extremely heavy rain hit this area in the 2016 summer. The result obtained by PANDA2 shows that soil more than 100 cm in depth will be potentially eroded at four points in three years to one hundred years.

Health Status of Sand Flathead (Platycephalus bassensis), Inhabiting an Industrialised and Urbanised Embayment, Port Phillip Bay, Victoria as Measured by Biomarkers of Exposure and Effects.

PubMed

Baker, Jarrad K; Long, Sara M; Hassell, Kathryn L; Pettigrove, Vincent J; Gagnon, Marthe M

2016-01-01

Port Phillip Bay, Australia, is a large semi-closed bay with over four million people living in its catchment basin. The Bay receives waters from the Yarra River which drains the city of Melbourne, as well as receiving the discharges of sewage treatment plants and petrochemical and agricultural chemicals. A 1999 study demonstrated that fish inhabiting Port Phillip Bay showed signs of effects related to pollutant exposure despite pollution management practices having been implemented for over a decade. To assess the current health status of the fish inhabiting the Bay, a follow up survey was conducted in 2015. A suite of biomarkers of exposure and effects were measured to determine the health status of Port Phillip Bay sand flathead (Platycephalus bassensis), namely ethoxyresorufin-O-deethylase (EROD) activity, polycyclic aromatic hydrocarbons (PAH) biliary metabolites, carboxylesterase activity (CbE) and DNA damage (8-oxo-dG). The reduction in EROD activity in the present study suggests a decline in the presence of EROD activity-inducing chemicals within the Bay since the 1990s. Fish collected in the most industrialised/urbanised sites did not display higher PAH metabolite levels than those in less developed areas of the Bay. Ratios of PAH biliary metabolite types were used to indicate PAH contaminant origin. Ratios indicated fish collected at Corio Bay and Hobsons Bay were subjected to increased low molecular weight hydrocarbons of petrogenic origin, likely attributed to the close proximity of these sites to oil refineries, compared to PAH biliary metabolites in fish from Geelong Arm and Mordialloc. Quantification of DNA damage indicated a localised effect of exposure to pollutants, with a 10-fold higher DNA damage level in fish sampled from the industrial site of Corio Bay relative to the less developed site of Sorrento. Overall, integration of biomarkers by multivariate analysis indicated that the health of fish collected in industrialised areas was compromised

Health Status of Sand Flathead (Platycephalus bassensis), Inhabiting an Industrialised and Urbanised Embayment, Port Phillip Bay, Victoria as Measured by Biomarkers of Exposure and Effects

PubMed Central

Baker, Jarrad K.; Long, Sara M.; Hassell, Kathryn L.; Pettigrove, Vincent J.

2016-01-01

Port Phillip Bay, Australia, is a large semi-closed bay with over four million people living in its catchment basin. The Bay receives waters from the Yarra River which drains the city of Melbourne, as well as receiving the discharges of sewage treatment plants and petrochemical and agricultural chemicals. A 1999 study demonstrated that fish inhabiting Port Phillip Bay showed signs of effects related to pollutant exposure despite pollution management practices having been implemented for over a decade. To assess the current health status of the fish inhabiting the Bay, a follow up survey was conducted in 2015. A suite of biomarkers of exposure and effects were measured to determine the health status of Port Phillip Bay sand flathead (Platycephalus bassensis), namely ethoxyresorufin-O-deethylase (EROD) activity, polycyclic aromatic hydrocarbons (PAH) biliary metabolites, carboxylesterase activity (CbE) and DNA damage (8-oxo-dG). The reduction in EROD activity in the present study suggests a decline in the presence of EROD activity-inducing chemicals within the Bay since the 1990s. Fish collected in the most industrialised/urbanised sites did not display higher PAH metabolite levels than those in less developed areas of the Bay. Ratios of PAH biliary metabolite types were used to indicate PAH contaminant origin. Ratios indicated fish collected at Corio Bay and Hobsons Bay were subjected to increased low molecular weight hydrocarbons of petrogenic origin, likely attributed to the close proximity of these sites to oil refineries, compared to PAH biliary metabolites in fish from Geelong Arm and Mordialloc. Quantification of DNA damage indicated a localised effect of exposure to pollutants, with a 10-fold higher DNA damage level in fish sampled from the industrial site of Corio Bay relative to the less developed site of Sorrento. Overall, integration of biomarkers by multivariate analysis indicated that the health of fish collected in industrialised areas was compromised

An assessment of the erodibility of Holocene lithounits comprising streambanks in northeastern Kansas, USA

NASA Astrophysics Data System (ADS)

Layzell, Anthony L.; Mandel, Rolfe D.

2014-05-01

Streambanks are the primary source of sediment for watersheds in the Midwestern USA. In much of this region, deposits of fine-grained Holocene alluvium comprising streambanks have been assigned to a single lithostratigraphic unit, the DeForest Formation. This study examines the stratigraphic relationships and measures the erodibility of the different members of the DeForest Formation in three watersheds in northeastern Kansas. Distinct differences in erodibility, measured in terms of critical shear stress (τc) by a submerged jet-test device, were observed between the different members of the DeForest Formation. The most erodible member is the Camp Creek Member (average τc = 1.0 Pa) while the most resistant is the Gunder Member (average τc = 10.4 Pa). Variability in erodibility between and within the members of the DeForest Formation is attributed to the magnitude of post-depositional soil-forming processes, including the presence of buried soils, as well as the inherent natural variability in the different parent materials. A weak positive correlation was found between percent clay and τc. Resistance to erosion by fluid flow was found to be significantly greater where clay contents exceed 28%. Although the Camp Creek Member was found to be the most erodible, it always occurs, stratigraphically, as the uppermost member. Available bankfull stage indicators suggest that bankfull discharges rarely attain elevations sufficient to erode Camp Creek Member deposits. Therefore, other members of the DeForest Formation are able to exert some control on the rate of bank erosion by hydraulic flow. Furthermore, given the observed differences in lithology, soil development and erodibility, the susceptibility to mass wasting processes is also likely to vary between the different members. Therefore, lithostratigraphic and soil-stratigraphic relationships have important implications for streambank erodibility and are crucial for accurately determining areas prone to streambank

Early responses measured in the brachyuran crab Carcinus maenas exposed to carbamazepine and novobiocin: application of a 2-tier approach.

PubMed

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

2013-11-01

One of the main consequences of the constant input of pharmaceuticals to the aquatic environment is that biota might develop unknown chronic effects, thus affecting their health even at low concentrations. The aim of this study is to evaluate the health status of Carcinus maenas employing a 2-tier approach, after 28 days of exposure to carbamazepine (CBZ) and novobiocin (NOV) at 0.1, 1, 10 and 50µgL(-1). Lysosomal membrane stability (LMS) is employed in tier 1. In tier 2 was applied a battery of biomarkers of exposure and effect (ethoxyresorufin O-deethylase (EROD), dibenzyl flourescein dealkylase (DBF), glutathione S-transferase (GST), glutathione peroxidase (GPx), lipid peroxidation (LPO) and DNA adducts) measured in gill, hepatopancreas, muscle and gonad tissues. Results show a dose-dependent effect. LMS in crabs exposed to environmental concentrations of pharmaceuticals was significantly lower compared to controls (p<0.05), indicating their stressed status. EROD activity was induced significantly (p<0.05) in all tissues by NOV (10-50µgL(-1)). DBF activity was induced significantly (p<0.05) in gill and hepatopancreas tissues by CBZ (10-50µgL(-1)). GST activity was activated in all tissues of crabs exposed to the highest concentrations tested (p<0.05). All tissues showed induction of GPX activity after exposure to selected drugs (p<0.05). LPO was activated in gill and hepatopancreas tissues by the pharmaceuticals at 50µgL(-1) (p<0.05). Crabs exposed to NOV (50µgL(-1)) presented DNA damage in gill and hepatopancreas tissues (p<0.05). Environmental concentrations of these pharmaceuticals have a measurable effect on the biomarkers studied. The 2-tier approach applied might be a suitable tool for the assessment of sublethal responses in crabs exposed to pharmaceuticals in the marine environment. Copyright © 2013 Elsevier Inc. All rights reserved.

Aggregate Stability and Erodibility of Purple Soil on Sloping Farmland as affected by different Soil Thickness

NASA Astrophysics Data System (ADS)

Huang, Xinjun; Zhang, Qingwen; Chen, Shanghong; Dong, Yuequn; Xiao, Meijia; Hamed, Lamy Mamdoh Mohamed

2017-04-01

Soil thickness is basic limiting condition for purple soil, not only due to its effect on crop production, but also its effect on soil structure. Steady-state of soil thickness will be achieved over time, as result the soil aggregate which the key factor of soil erodibility can be enhanced as well. However, the effect of soil thickness on aggregates stability and the characteristics of soil erodibility in sloping land have not yet fully understood.A field survey was conducted in hilly area of Sichuan region located in southeast China to study the relationship between soil aggregate stability and soil erodibility on sloping farmland under different four thickness (100cm, 80cm, 60cm, 30cm) of purple soil. Based on two different sieving methods (Dry and Wet sieving), we analyzed soil aggregate stability and its effect on soil erodibility within depth of 0-30cm soil layers. The results indicated that: Water stable aggregate on sloping farmland was ranged between 37.9% to 58.6%, where it increased with increasing the soil thickness. Moreover, fractal dimension calculated from dry-sieving and wet-sieving was 2.06-2.49 and 2.70-2.85 respectively, where it decreased with decreasing the soil thickness. The overall soil erodibility was 0.05-1.00 and a negative significant correlation was found between soil aggregate stability and erodibility(P<0.01). Moreover, farmland with thick soil profile tended to be high in soil erodibility within the top soil layer (0-30cm). The results reveal that soil thickness can affect soil aggregate stability as well as erodibility. As soil thickness increased, the top soil became more stable and less erodible. Keywords：purple soil; soil thickness; soil aggregate；soil erodibility

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.

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

movement and deposition along the flatter model sector. Crosta G. (1992) An example of unusual complex landslide: from a rockfall to a dry granular flow. Geol. Romana, 30, 175-184 Crosta G.B., S. Imposimato, D.G. Roddeman (2006) Continuum numerical modelling of flow-like landslides. Landslides from massive rock slope failure, Evans, S.G., Scarascia Mugnozza, G., Strom, A., Hermanns, R., (eds) NATO Science Series, Earth and Environmental Sciences, 49, 211-232 Crosta, G.B., Imposimato, S., and D.G. Roddeman, (2008a) Approach to numerical modelling of long runout landslides. Hong Kong, GCO, Dec. 2007, Proc Inter. Forum on Landslide Disaster Management, 20 pp. Crosta, G.B., Imposimato, S., and D.G. Roddeman, (2008b) Numerical modelling of entrainment/deposition in rock and debris-avalanches. Engineering Geology, 109, 1-2, 135-145. Crosta, G. B., Imposimato, S., and D. Roddeman (2009) Numerical modeling of 2-D granular step collapse on erodible and nonerodible surface. J. Geophys. Res., 114,F03020. Crosta, G. B., Imposimato, S., D. Roddeman, P. Frattini (2011) On controls of flow-like landslide evolution by an erodible layer. Proceedings of the Second World Landslide Forum - 3-7 October 2011, Rome Dufresne, A., Davies, T., McSaveney, M. (2010) Influence of runout-path material on emplacement of the Round Top rock avalanche, New Zealand. Earth Surf. Proc. Land. 35, 190-201. Hungr O, Evans SG. (2004) Entrainment of debris in rock avalanches; an analysis of a long run-out mechanism. Geological Society of America Bulletin 116(9-10): 1240-1252. Mangeney, A., Roche, O., Hungr, O., Mangold, Faccanoni, G., and Lucas, A. , (2010). Erosion and mobility in granular collapse over sloping beds. J. Geophys. Res. - Earth Surface, 115, F03040

Erodibility of waste (Loess) soils from construction sites under water and wind erosional forces.

PubMed

Tanner, Smadar; Katra, Itzhak; Argaman, Eli; Ben-Hur, Meni

2018-03-01

Excess soils from construction sites (waste soils) become a problem when exposed to soil erosion by water or wind. Understanding waste soil erodibility can contribute to its proper reuse for various surface applications. The general objective of the study was to provide a better understanding of the effects of soil properties on erodibility of waste soils excavated from various depths in a semiarid region under rainfall and wind erosive forces. Soil samples excavated from the topsoil (0-0.3m) and subsoil layers (0.3-0.9 and >1m depths) were subjected to simulated rainfall and wind. Under rainfall erosive forces, the subsoils were more erodible than the topsoil, in contrast to the results obtained under wind erosive forces. Exchangeable sodium percentage was the main factor controlling soil erodibility (K i ) under rainfall, and a significant logarithmic regression line was found between these two parameters. In addition, a significant, linear regression was found between K i and slaking values for the studied soil samples, suggesting that the former can be predicted from the latter. Soil erodibility under wind erosion force was controlled mainly by the dry aggregate characteristics (mean weight diameter and aggregate density): their higher values in the subsoil layers resulted in lower soil erodibility compared to the topsoil. Copyright © 2017 Elsevier B.V. All rights reserved.

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)

The aflatoxin B1 -fumonisin B1 toxicity in BRL-3A hepatocytes is associated to induction of cytochrome P450 activity and arachidonic acid metabolism.

PubMed

Mary, Verónica S; Arias, Silvina L; Otaiza, Santiago N; Velez, Pilar A; Rubinstein, Héctor R; Theumer, Martín G

2017-06-01

Human oral exposure to aflatoxin B 1 (AFB 1 ) and fumonisin B 1 (FB 1 ) is associated with increased hepatocellular carcinoma. Although evidence suggested interactive AFB 1 -FB 1 hepatotoxicity, the underlying mechanisms remain mostly unidentified. This work was aimed at evaluating the possible AFB 1 -FB 1 interplay to induce genetic and cell cycle toxicities in BRL-3A rat hepatocytes, reactive oxygen species (ROS) involvement, and the AFB 1 metabolizing pathways cytochrome P450 (CYP) and arachidonic acid (ArAc) metabolism as ROS contributors. Flow cytometry of stained BRL-3A hepatocytes was used to study the cell cycle (propidium iodide), ROS intracellular production (DCFH-DA, HE, DAF-2 DA), and phospholipase A activity (staining with bis-BODIPY FL C11-PC). The CYP1A activity was assessed by the 7-ethoxyresorufin-O-deethylase (EROD) assay. Despite a 48-h exposure to FB 1 (30 μM) not being genotoxic, the AFB 1 (20 μM)-induced micronucleus frequency was overcome by the AFB 1 -FB 1 mixture (MIX), presumably showing toxin interaction. The mycotoxins blocked G1/S-phase, but only MIX caused cell death. Overall, the oxidative stress led these alterations as the pretreatment with N-acetyl-l-cysteine reduced such toxic effects. While AFB 1 had a major input to the MIX pro-oxidant activity, with CYP and ArAc metabolism being ROS contributors, these pathways were not involved in the FB 1 -elicited weak oxidative stress. The MIX-induced micronucleus frequency in N-acetyl-l-cysteine pretreated cells was greater than that caused by AFB 1 without antioxidants, suggesting enhanced AFB 1 direct genotoxicity probably owing to the higher CYP activity and ArAc metabolism found in MIX. The metabolic pathways modulation by AFB 1 -FB 1 mixtures could raise its hepatocarcinogenic properties. © 2017 Wiley Periodicals, Inc.

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

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

USDA-ARS?s Scientific Manuscript database

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...

Toxicity of sediments from Bahía de Chetumal, México, as assessed by hepatic EROD induction and histology in nile tilapia Oreochromis niloticus.

PubMed

Zapata-Pérez, O; Simá-Alvarez, R; Noreña-Barroso, E; Güemes, J; Gold-Bouchot, G; Ortega, A; Albores-Medina, A

2000-01-01

The effect of environmental pollutants present in sediments obtained from Bahía de Chetumal, a bay on the border between Mexico and Belize, was studied in nile tilapia (Oreochromis niloticus) intraperitoneally injected with sediment extracts from six different sites of the Bay. Sediment samples used for the study contained a variety of organic chemicals such as organochlorine pesticides, polychlorinated biphenyls (PCBs) and polynuclear aromatic hydrocarbons (PAHs). Total cytochrome P-450 and EROD activity were measured in fish liver. Haematological and histological analyses were also carried out. Hepatic P-450 content in treated fish increased from 43 to 240%, and EROD activity from 85 to 160% compared to controls. Extracts from two sampling sites inhibited EROD activity. There were positive significant correlations between P-450 content and the levels of PCBs 44 and 128. EROD activity correlated to HCB, op'-DDE, pp'-DDE, pp'-DDD, mirex and PCB 18 concentrations. Blood examination showed cell degeneration and binucleated leukocytes with abnormal chromatin. Extract treatment also resulted in foci of hyperplasia on the basement of gill lamellae, hypertrophy and oedema in gills and liver necrosis. Control fish showed no abnormalities. The results demonstrate that sediments from Bahía of Chetumal have the potential to cause histopathological, haematological and biochemical alterations in fish. The administration of sediment extracts to fish may serve as a useful test to screen the toxicity of sediments from different areas.

The synergistic effects of insecticidal essential oils and piperonyl butoxide on biotransformational enzyme activities in Aedes aegypti (Diptera: Culicidae).

PubMed

Waliwitiya, Ranil; Nicholson, Russell A; Kennedy, Christopher J; Lowenberger, Carl A

2012-05-01

The biochemical mechanisms underlying the increased toxicity of several plant essential oils (thymol, eugenol, pulegone, terpineol, and citronellal) against fourth instar of Aedes aegypti L. when exposed simultaneously with piperonyl butoxide (PBO) were examined. Whole body biotransformational enzyme activities including cytochrome P450-mediated oxidation (ethoxyresorufin O-dethylase [EROD]), glutathione S-transferase (GST), and beta-esterase activity were measured in control, essential oil-exposed only (single chemical), and essential oil + PBO (10 mg/liter) exposed larvae. At high concentrations, thymol, eugenol, pulegone, and citronellal alone reduced EROD activity by 5-25% 16 h postexposure. Terpineol at 10 mg/liter increased EROD activity by 5 +/- 1.8% over controls. The essential oils alone reduced GST activity by 3-20% but PBO exposure alone did not significantly affect the activity of any of the measured enzymes. All essential oils in combination with PBO reduced EROD activity by 58-76% and reduced GST activity by 3-85% at 16 h postexposure. This study indicates a synergistic interaction between essential oils and PBO in inhibiting the cytochrome P450 and GST detoxification enzymes in Ae. aegypti.

Growth of Planted Yellow-Poplar After Vertical Mulching and Fertilization on Eroded Soils

Treesearch

J.B. Baker; B.G. Blackmon

1976-01-01

Fertilization and vertical mulching improved height growth of yellow-poplars planted on eroded soils. A growing demand for hardwood timber accompanied by a diminishing land base has prompted land managers to consider planting hardwoods on marginal sites such as the eroded soils in the Silty Uplands of Arkansas, Louisiana, and Mississippi. Many of these areas were well...

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

USGS Publications Warehouse

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

1991-01-01

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

Influence of bleaching agents on surface roughness of sound or eroded dental enamel specimens.

PubMed

Azrak, Birgül; Callaway, Angelika; Kurth, Petra; Willershausen, Brita

2010-12-01

The aim of the present in vitro study was to assess the effect of bleaching agents on eroded and sound enamel specimens. Enamel specimens prepared from human permanent anterior teeth were incubated with different bleaching agents containing active ingredients as 7.5 or 13.5% hydrogen peroxide or 35% carbamide peroxide, ranging in pH from 4.9 to 10.8. The effect of the tooth whitening agents on surface roughness was tested for sound enamel surfaces as well as for eroded enamel specimens. To provoke erosive damage, the enamel specimens were incubated for 10 hours with apple juice (pH = 3.4). Afterwards, pretreated and untreated dental slices were incubated with one of the bleaching agents for 10 hours. The surface roughness (R(a)) of all enamel specimens (N = 80) was measured using an optical profilometric device. A descriptive statistical analysis of the R(a) values was performed. The study demonstrated that exposure to an acidic bleaching agent (pH = 4.9) resulted in a higher surface roughness (p = 0.043) than treatment with a high peroxide concentration (pH = 6.15). If the enamel surface was previously exposed to erosive beverages, subsequent bleaching may enhance damage to the dental hard tissue. Bleaching agents with a high concentration of peroxide or an acidic pH can influence the surface roughness of sound or eroded enamel. © 2010, COPYRIGHT THE AUTHORS. JOURNAL COMPILATION © 2010, WILEY PERIODICALS, INC.

Biochemical responses, morphometric changes, genotoxic effects and CYP1A expression in the armored catfish Pterygoplichthys anisitsi after 15 days of exposure to mineral diesel and biodiesel.

PubMed

Arantes Felício, Andréia; Martins Parente, Thiago Estevam; Regina Maschio, Lucilene; Nogueira, Lílian; Rodrigues Venancio, Larissa Paola; de Freitas Rebelo, Mauro; Schlenk, Daniel; de Almeida, Eduardo Alves

2015-05-01

Despite being considered friendlier to the environment, biodiesel fuel can be harmful to aquatic organisms, especially when combined with petroleum diesel fuel. In this work we evaluated the effects of mineral diesel fuel containing increasing concentrations of biodiesel (5% and 20%, namely B5 and B20) and pure biodiesel (B100), at concentrations of 0.001 and 0.01mLL(-1), after 15 days of exposure, in armored catfish (Pterygoplichtys anisitsi). Toxicity tests were also performed to estimate LC50 values (96h) for each compound. Biotransformation enzymes [ethoxyresorufin-O-deethylase (EROD), and glutathione S-transferase (GST)] as well as oxidative stress markers (superoxide dismutase, SOD, catalase, CAT, glutathione peroxidase, GPx, and the level of lipid peroxidation) were measured in liver and gills after treatment. Genotoxic effects were also accessed in erythrocytes using the comet assay and by evaluating the frequency of micronuclei formation. Further, the mRNA of cytochrome P450 1A (CYP1A) was also measured in liver. Mortality was not observed even exposure to concentrations as high as 6.0mLL(-1). EROD and GST activities were increased after B5 and B20 treatments; however, CYP1A mRNA induction was not observed. SOD and CAT activities were decreased, but GPx was significantly higher for all treatments in gills. There were no significant changes in lipid peroxidation, but genotoxicity markers revealed that all treatments increased comet scores. Fuels B5 and B20 increased micronuclei frequency. Our results indicate that despite being less toxic, biodiesel may cause sublethal alterations in fish that may alter long term health. Copyright © 2015 Elsevier Inc. All rights reserved.

Persistence and dioxin-like toxicity of carbazole and chlorocarbazoles in soil.

PubMed

Mumbo, John; Henkelmann, Bernhard; Abdelaziz, Ahmed; Pfister, Gerd; Nguyen, Nghia; Schroll, Reiner; Munch, Jean Charles; Schramm, Karl-Werner

2015-01-01

Halogenated carbazoles have recently been detected in soil and water samples, but their environmental effects and fate are unknown. Eighty-four soil samples obtained from a site with no recorded history of pollution were used to assess the persistence and dioxin-like toxicity of carbazole and chlorocarbazoles in soil under controlled conditions for 15 months. Soil samples were divided into two temperature conditions, 15 and 20 °C, both under fluctuating soil moisture conditions comprising 19 and 44 drying-rewetting cycles, respectively. This was characterized by natural water loss by evaporation and rewetting to -15 kPa. Accelerated solvent extraction (ASE) and cleanup were performed after incubation. Identification and quantification were done using high-resolution gas chromatogram/mass spectrometer (HRGC/MS), while dioxin-like toxicity was determined by ethoxyresorufin-O-deethylase (EROD) induction in H4IIA rat hepatoma cells assay and multidimensional quantitative structure-activity relationships (mQSAR) modelling. Carbazole, 3-chlorocarbazole and 3,6-dichlorocarbazole were detected including trichlorocarbazole not previously reported in soils. Carbazole and 3-chlorocarbazole showed significant dissipation at 15 °C but not at 20 °C incubating conditions indicating that low temperature could be suitable for dissipation of carbazole and chlorocarbazoles. 3,6-Dichlorocarbazole was resistant at both conditions. Trichlorocarbazole however exhibited a tendency to increase in concentration with time. 3-Chlorocarbazole, 3,6-dibromocarbazole and selected soil extracts exhibited EROD activity. Dioxin-like toxicity did not decrease significantly with time, whereas the sum chlorocarbazole toxic equivalence concentrations (∑TEQ) did not contribute significantly to the soil assay dioxin-like toxicity equivalent concentrations (TCDD-EQ). Carbazole and chlorocarbazoles are persistent with the latter also toxic in natural conditions.

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.

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

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

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 lessmore » 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.« less

Prediction of erodibility in Oxisols using iron oxides, soil color and diffuse reflectance spectroscopy

NASA Astrophysics Data System (ADS)

Arantes Camargo, Livia; Marques, José, Jr.

2015-04-01

The prediction of erodibility using indirect methods such as diffuse reflectance spectroscopy could facilitate the characterization of the spatial variability in large areas and optimize implementation of conservation practices. The aim of this study was to evaluate the prediction of interrill erodibility (Ki) and rill erodibility (Kr) by means of iron oxides content and soil color using multiple linear regression and diffuse reflectance spectroscopy (DRS) using regression analysis by least squares partial (PLSR). The soils were collected from three geomorphic surfaces and analyzed for chemical, physical and mineralogical properties, plus scanned in the spectral range from the visible and infrared. Maps of spatial distribution of Ki and Kr were built with the values calculated by the calibrated models that obtained the best accuracy using geostatistics. Interrill-rill erodibility presented negative correlation with iron extracted by dithionite-citrate-bicarbonate, hematite, and chroma, confirming the influence of iron oxides in soil structural stability. Hematite and hue were the attributes that most contributed in calibration models by multiple linear regression for the prediction of Ki (R2 = 0.55) and Kr (R2 = 0.53). The diffuse reflectance spectroscopy via PLSR allowed to predict Interrill-rill erodibility with high accuracy (R2adj = 0.76, 0.81 respectively and RPD> 2.0) in the range of the visible spectrum (380-800 nm) and the characterization of the spatial variability of these attributes by geostatistics.

Assessment of Lemna minor (duckweed) and Corbicula fluminea (freshwater clam) as potential indicators of contaminated aquatic ecosystems: responses to presence of psychoactive drug mixtures.

PubMed

Bourioug, Mohamed; Mazzitelli, Jean-Yves; Marty, Pierre; Budzinsky, Hélène; Aleya, Lotfi; Bonnafé, Elsa; Geret, Florence

2018-04-01

The pharmaceutical products are emerging pollutants continuously released into the environment, because they cannot be effectively removed by the wastewater treatment plants. In recent years, questions have been raised concerning the environmental risks related to these pollutants. The goal of this research was to evaluate the responses in Lemna minor after 7 days and in Corbicula fluminea after differing durations (1, 3, 7, and 19 days) of exposure to the psychoactive drug mixture (valproic acid, citalopram, carbamazepine, cyamemazine, hydroxyzine, oxazepam, norfluoxetine, lorazepam, fluoxetine, and sertraline) in different concentrations (0, 0 + ethanol, drug concentration (DC) 1 = river water concentration, DC2 = effluent concentration, and DC3 = 10× effluent concentration). In this aim, growth parameters of L. minor, gluthathione S-transferase (GSTs), catalase (CAT), ethoxyresorufin-O-deethylase (EROD) and/or gene expressions (pi-gst, cat, cytochrome P450 4 (cyp4), multidrug resistant 1 (mdr1), and superoxide dismutase (sod)) were measured. GST activities increased significantly in L. minor exposed to DC3, but no changes were found in CAT activity. In C. fluminea, EROD activity was induced significantly in both gill and digestive gland tissues after 3 days' exposure to DC3, while a GST increase was observed only in digestive gland tissues, suggesting that these pharmaceuticals induced an oxidative effect. Gene expression analysis revealed transient transcriptomic responses of cyp4, sod, and mdr1 under drug concentrations 2 or 3 and no change of expression for the other genes (cat and pi-gst) or condition (environmental drug concentration) tested. Finally, the data reported in this study represent important ecotoxicological information, confirming that this enzyme family (cyp4, sod, and mdr1) may be considered as a sensible and early indicator of exposure to drugs and emphasizing the involvement of selected genes in detoxification pathways.

Interactive effects of hypoxia and PCB co-exposure on expression of CYP1A and its potential regulators in Atlantic croaker liver.

PubMed

Rahman, Md Saydur; Thomas, Peter

2018-04-01

Although marine and coastal environments which are contaminated with xenobiotic organic compounds often become hypoxic during the summer, the interactive effects of hypoxia and xenobiotic exposure on marine species such as teleost fishes remain poorly understood. The expression and activity of monooxygenase enzyme cytochrome P450-1A (CYP1A) in fishes are upregulated by exposure to polychlorinated biphenyls (PCBs), whereas they are down-regulated during hypoxia exposure. We investigated the interactive effects of hypoxia and PCB co-exposure on hepatic CYP1A expression in Atlantic croaker and on potential regulators of CYP1A. Croaker were exposed to hypoxia (1.7 mg/L dissolved oxygen), 3,3',4,4'-tetrachlorobiphenyl (PCB 77, dose: 2 and 8 µg/g body weight), and Aroclor 1254 (a common PCB mixture, dose: 0.5 and 1 µg/g body weight), alone and in combination for 4 weeks. PCB 77 exposure markedly increased hepatic CYP1A mRNA and protein expression, and ethoxyresorufin-O-deethylase (EROD, an indicator of CYP1A enzyme) activity and increased endothelial nitric oxide synthase (eNOS) protein expression. PCB 77 treatment also increased interleukin-1β (IL-1β, a cytokine) mRNA levels and protein carbonyl (PC, an indicator of reactive oxygen species, ROS) contents. These marked PCB 77- and Aroclor 1254-induced increases in CYP1A mRNA levels and EROD activity were significantly attenuated by co-exposure to hypoxia, whereas the increases in hepatic eNOS protein and IL-1β mRNA expression, and PC contents were augmented by hypoxia co-exposure. The results suggest that biotransformation of organic xenobiotics by CYP1A is reduced in fish during co-exposure to hypoxia and is accompanied by alterations in eNOS, ROS, and IL-1β levels. © 2018 Wiley Periodicals, Inc.

Mammalian cell line-based bioassays for toxicological evaluation of landfill leachate treated by Pseudomonas sp. ISTDF1.

PubMed

Ghosh, Pooja; Das, Mihir Tanay; Thakur, Indu Shekhar

2014-01-01

Landfill leachate has become a serious environmental concern because of the presence of many hazardous compounds which even at trace levels are a threat to human health and environment. Therefore, it is important to assess the toxicity of leachate generated and discharge it conforming to the safety standards. The present work examined the efficiency of an earlier reported Pseudomonas sp. strain ISTDF1 for detoxification of leachate collected from Okhla landfill site (New Delhi, India). GC-MS analysis performed after treatment showed the removal of compounds like alpha-limonene diepoxide, brominated dioxin-2-one, Bisphenol A, nitromusk, phthalate derivative, and nitrobenzene originally found in untreated leachate. ICP-AES analysis for heavy metals also showed reduction in concentrations of Zn, Cd, Cr, Fe, Ni, and Pb bringing them within the limit of safety discharge. Methyl tetrazolium (MTT) assay for cytotoxicity, alkaline comet assay for genotoxicity, and 7-ethoxyresorufin-O-deethylase (EROD) assay for dioxin-like behavior were carried out in human hepato-carcinoma cell line HepG2 to evaluate the toxic potential of treated and untreated leachates. The bacterium reduced toxicity as shown by 2.5-fold reduction of MTT EC50 value, 7-fold reduction in Olive Tail Moment, and 2.8-fold reduction in EROD induction after 240 h of bacterial treatment.

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.

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.

Biomarkers in fish as a measure of the state of marine environment of Kuwait.

PubMed

Beg, M U; Butt, S A; Al-Dufaileej, S; Karam, Q; Al-Sharrah, T K; Saeed, T

2018-05-04

The health of a marine ecosystem can effectively be monitored by studying the levels of biomarkers in a representative species. A change in background level of a biomarker indicates exposure to a specific type of pollutants. It also identifies bioavailability and the organism response to the causative agent among the compounds present in the surrounding water body. Yellowfin seabream (Acanthopagrus latus), a local variety of fish, was examined for parent PAHs in the liver, its metabolites in bile by the GC-MS method as exposure biomarkers and cytochrome P4501A1 by assay of ethoxyresorufin-o-deethylase (EROD) in the liver as an effect biomarker. A comparison was made between fish collected in 2015 with the fish collected in 2005-2006 and stored at - 80 °C in the fish bank. The objective was to examine the extent of changes in the environmental quality of the Kuwait marine area and the status of fish health concerning oil-related pollutants since Arabian Gulf is surrounded by oil-producing countries. Interestingly, insignificant differences between the liver PAH content and EROD activity were observed in fish over the sampling periods. The fish efficiently metabolized PAHs and excreted hydroxy-metabolites in bile. The study suggested that environmental quality of the Kuwait marine area was not deteriorated to any serious extent in the last decade and biomarkers can be used effectively in assessing the thrust of sub-optimal levels of various contaminants present in the marine area on the resident biota.

Maintenance of in vivo induced cytochrome P-450s in hepatocyte monolayers at non freezing temperatures.

PubMed

Evans, Peter J

2015-04-01

Cytochrome P450s (CYPs) induced in rats by 3-methylcholanthrene (3-MC), phenobarbital (PB) and dexamethasone (Dex) were investigated. The inducers had no effect on hepatocyte yield, viability, attachment or spreading on collagen. 3-MC induced ethoxyresorufin deethylase (EROD). Under normothermic conditions the activity fell in culture. However, it was maintained when cells were preserved at 10°C under a gelatin gel. Upon reactivation the activity mirrored that of freshly isolated cells at 37°C. Induced levels were stable for at least 6h , the time to form a confluent monolayer. The investigation was extended to other CYPs by looking at patterns of testosterone metabolism. Phenobarbital had the greatest influence in terms of the quantity and number of metabolites. Culture at 37°C decreased the peaks dramatically within 24 h. All 7 peaks were maintained in the preservation system. Copyright © 2015 Elsevier Inc. All rights reserved.

Stabilization of erodible slopes with geofibers and nontraditional liquid additives.

DOT National Transportation Integrated Search

2013-05-01

Instability of erodible slopes due to extreme climate events and of permafrost slopes due degradation and thawing is a significant : engineering problem for northern transportation infrastructure. Engineers continually look for mitigation alternative...

75 FR 75961 - Notice of Implementation of the Wind Erosion Prediction System for Soil Erodibility System...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-12-07

... Wind Erosion Prediction System for Soil Erodibility System Calculations for the Natural Resources... Erosion Prediction System (WEPS) for soil erodibility system calculations scheduled for implementation for... computer model is a process-based, daily time-step computer model that predicts soil erosion via simulation...

PPARalpha-dependent modulation of hepatic CYP1A by clofibric acid in rats.

PubMed

Shaban, Zein; El-Shazly, Samir; Ishizuka, Mayumi; Kimura, Kazuhiro; Kazusaka, Akio; Fujita, Shoichi

2004-09-01

Fibrates, hypolipidemic drugs, have been reported to suppress the metabolic activities of cytochrome P450 1A1 and 1A2 in rats but the mechanism has not been elucidated. In the present study we tested the hypothesis that the inhibitory effect of fibrates on arylhydrocarbon receptor (AhR) function may be due to their stimulatory effects on PPARalpha. Sudan III (S.III) treatment induced CYP 1A1 and CYP 1A2 protein expression, mRNA and their metabolic activities, methoxyresorufin-O-demethylase (MROD) and ethoxyresorufin-O-deethylase (EROD), in Wistar rats higher than those in the control. Co-treatment of rats with S.III and clofibric acid (CA) caused a 40-50% decrease in the induced levels of CYP1A1 and CYP1A2 protein, mRNA expression and their metabolic activities and reduced AhR protein expression. When we treated HepG2 cells with S.III and/or CA, no suppressive effect on S.III-induced CYP1A1 protein expression due to CA was found. HepG2 cells were transiently transfected with increasing concentrations of PPARalpha mammalian expression vector and exposed to the same treatment. CA co-treatment with S.III decreased AhR protein and S.III-induced CYP1A1 protein expression with increasing dose of PPARalpha transfected into HepG2 cells. Our results demonstrate that the suppressive effect of fibrates on CYP1A is PPARalpha-dependent and suggest that PPARalpha has an inhibitory effect on AhR function.

Long-Term Bond Strength of Two Benzalkonium Chloride-Modified Adhesive Systems to Eroded Dentin

PubMed Central

Lussi, Adrian; Peutzfeldt, Anne

2017-01-01

This study investigated the effect of benzalkonium chloride (BAC) modification of two adhesive systems on long-term bond strength to normal and artificially eroded dentin. A total of 128 extracted human molars were sectioned and the buccal and oral surfaces of each molar were ground until the dentin. One half was left untreated (normal dentin) while the other half underwent artificial erosion. Resin composite was bonded to the buccal or oral surface following treatment with Adper Scotchbond 1XT or OptiBond FL without or with 1% BAC incorporation. Shear bond strength (SBS) was measured after 24 h (100% humidity, 37°C) or 1 year (tap water, 37°C). SBS results were statistically analyzed (α = 0.05). SBS was significantly lower to artificially eroded dentin than to normal dentin (p < 0.001). Storage for 1 year had no effect on SBS to normal dentin but led to a significant decrease in SBS to artificially eroded dentin (p < 0.001). BAC incorporation decreased the 24 h SBS to normal dentin (p = 0.018), increased the 24 h SBS to eroded dentin (p = 0.001), and had no effect on the 1-year SBS for either substrate. Consequently, BAC incorporation did not improve bond durability. PMID:28875148

Estrogenicity and intersex in juvenile rainbow trout (Oncorhynchus mykiss) exposed to Pine/Eucalyptus pulp and paper production effluent in Chile.

PubMed

Chiang, Gustavo; Barra, Ricardo; Díaz-Jaramillo, Mauricio; Rivas, Meyling; Bahamonde, Paulina; Munkittrick, Kelly R

2015-07-01

Pulp and paper mill effluents (PPMEs) have been shown to increase gonad size, cause early maturation, and disrupt hormone functions in native and non-native Chilean fish. In this study, we assessed reproductive (plasma vitellogenin; VTG, gonad development) and metabolic (ethoxyresorufin-O-deethylase activity; EROD) end points, relative liver size (LSI) and condition factor (K) of juvenile female and male rainbow trout exposed to effluents. Unlike previous studies, which have focus either on the specific effects of effluent on fish in laboratory exposures or biotic population statuses downstream of discharge sites, we simultaneously assessed the impacts of PPMES on trout using two approaches: (1) laboratory exposures of tertiary treated PPME produced from processing Eucalyptus globulus or Pinus radiata; and (2) in situ bioassay downstream of the combined discharge of the same pulp mill. Despite an increase in the average gonadosomatic index (GSI) in exposed fish, no statistical differences in gonad size between exposed and unexposed individuals was detected. However, both female and male fish exposed to effluents showed significantly higher concentrations of plasma VTG, so more in fish exposed to Eucalyptus-based effluent when compared to Pinus PPME. In addition, male fish showed intersex characteristics in all exposure assays (Eucaliptus and Pinus) and, despite the low concentration of effluent in the river (<1% [v/v]), similar responses were observed in the caged fish. Finally, EROD activity was induced in both in situ exposures and laboratory assays at the higher PPME concentration (60-85% PPME). This study confirms estrogenic effects in Chilean fish exposed to PPME and the necessity for biological effects monitoring in addition to the assessment of physical-chemical endpoints as required in current government regulations. Copyright © 2015 Elsevier B.V. All rights reserved.

Does Aggregation Affect the Redistribution and Quality of Eroded SOC?

NASA Astrophysics Data System (ADS)

Hu, Yaxian; Kuhn, Nikolaus

2015-04-01

A substantial amount of literature has discussed the impacts of soil erosion on global carbon cycling. However, numerous gaps in our knowledge remain unaddressed, for instance, the biogeochemical fate of displaced SOC during transport being one of them. The transport distance and the quality of eroded SOC are the two major factors that determine its fate. Previous laboratory-based research had demonstrated that the effects of aggregation can potentially shorten the transport distance of eroded SOC. The mineralization potential of SOC also differs in sediment fractions of different likely transport distances. It is therefore essential to examine the transport distance and quality of eroded SOC under field conditions with natural rainfall as the agent of erosion. Soil samples from a silty clay soil from Switzerland and a sandy soil from Denmark, were collected in the field this summer after natural rainfall events. The soil from Switzerland was sampled from a field of maize in St. Ursanne (47°20' N 7°09' E) on August 6th, 2014 after a natural rainfall event. A depositional fan consisting of aggregated sediment was formed outside the lower edge of the field. The sandy soil from Denmark was sampled from a farm in Foulum (56°30' N, 9°35' W) on September 4, 2014, after a series of natural rainfall events. Soil samples were collected at different topographic positions along the two slopes. All the soil samples from the two farms were fractionated by a settling tube. Bulk soil from Switzerland and Denmark was also dispersed by ultrasound. The SOC contents of all bulk soils and associated fractions were determined using a carbon analyzer Leco 612 at 1000°C. The quality of SOC in different settling fractions collected from various topographic positions were also determined by stable isotopes of C and N (13C and 15N). Our results show that 1) the aggregate specific SOC distribution evidently differs from the mineral particle specific SOC distribution, indicating that re

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

Criteria for predicting scour of erodible rock in West Virginia.

DOT National Transportation Integrated Search

2013-09-01

The research project Criteria for Predicting Scour of Erodible Rock in West Virginia (RP-273) was conducted to characterize the hydraulic scour of rock at : 15 selected bridge sites in West Virginia (at least one site in each of WVDOHs ten d...

Effects of tributyltin (TBT) on in vitro hormonal and biotransformation responses in Atlantic salmon (Salmo salar).

PubMed

Mortensen, Anne S; Arukwe, Augustine

2009-01-01

The mechanisms by which the biocide tributyltin (TBT) and its metabolites affect the hormonal and xenobiotic biotransformation pathways in aquatic species are not well understood. In this study hepatocytes isolated from salmon were used to evaluate the mechanistical effects of TBT on fish hormonal and xenobiotic biotransformation pathways. Cells were exposed to 0.01, 0.1, 1, or 5 microM TBT and samples were collected at 0, 12, 24, or 48 h following exposure. Gene expression patterns were evaluated using quantitative polymerase chain reaction (PCR), and cytochrome P-450 (CYP)-mediated enzyme activities were evaluated by ethoxyresorufin, benzyloxyresorufin, and pentoxyresorufin O-deethylase (EROD, BROD, and PROD, respectively) activity assays. Generally, exposure of hepatocytes to 1 microM (at 48 h) and 5 microM TBT (at 12, 24, and 48 h) consistently produced reductions in all mRNA species investigated. TBT produced significant decreases of vitellogen (Vtg) expression at 48 h and modified the expression patterns of estrogen receptors (ERalpha and ERbeta) and androgen receptor-beta (ARbeta) that were dependent on time and TBT concentration. In the xenobiotic biotransformation pathway, TBT produced differential expression patterns that were dependent on exposure time and concentration for all salmonid AhR2 isoforms (AhR2alpha, AhR2beta, AhR2delta, and AhR2gamma). For CYP1A1, CYP3A, AhRR, and Arnt mRNA, TBT produced exposure- and time-specific modulations. Catalytic CYP activities showed that BROD activity increased in an apparent concentration-specific manner in cells exposed to TBT for 12 h. Interestingly, EROD activity showed a TBT concentration-dependent increase at 24 h and PROD at 12 and 48 h of exposure. In general our data show that TBT differentially modulated hormonal and biotransformation responses in the salmon in vitro system. The apparent and consistent decrease of the studied responses with time in 1 and 5 microM exposed hepatocytes suggest a possible

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.

Salt Efflorescence Effects on Soil Surface Erodibility and Dust Emissions

NASA Astrophysics Data System (ADS)

Van Pelt, R. S.; Zhang, G.

2017-12-01

Soluble salts resulting from weathering of geological materials often form surface crusts or efflorescences in areas with shallow saline groundwater. In many cases, the affected areas are susceptible to wind erosion due to their lack of protective vegetation and their flat topography. Fugitive dusts containing soluble salts affect the biogeochemistry of deposition regions and may result in respiratory irritation during transport. We created efflorescent crusts on soil trays by surface evaporation of single salt solutions and bombarded the resultant efflorescences with quartz abrader sand in a laboratory wind tunnel. Four replicate trays containing a Torrifluvent soil affected by one of nine salts commonly found in arid and semiarid streams were tested and the emissions were captured by an aspirated multi-stage deposition and filtering system. We found that in most cases the efflorescent crust reduced the soil surface erodibility but also resulted in the emission of salt rich dust. Two of the salts, sodium thiosulfate and calcium chloride, resulted in increased soil volume and erodibility. However, one of the calcium chloride replicates was tested after an outbreak of humid air caused hygroscopic wetting of the soil and it became indurated upon drying greatly decreasing the erodibility. Although saline affected soils are not used for agricultural production and degradation is not a great concern, the release of salt rich dust is an area of environmental concern and steps to control the dust emissions from affected soils should be developed. Future testing will utilize suites of salts found in streams of arid and semiarid regions.

Natural succession on abandoned cropland effectively decreases the soil erodibility and improves the fungal diversity.

PubMed

Zhang, Chao; Liu, Guobin; Song, Zilin; Qu, Dong; Fang, Linchuan; Deng, Lei

2017-10-01

Changes in plants and soils during natural succession have been evaluated, but little is known about the effects of succession on the activities of soil microbes and their interactions with soil erodibility. We conducted a field study on the Chinese Loess Plateau, typical of this semiarid area, to determine the effect of secondary succession on the stability of soil structure against erosion and on the composition of soil fungal communities. Characteristics of plant, soil, and fungal communities were assessed across a 30-yr chronosequence of grassland developed from abandoned cropland. The diversity and composition of the fungal communities were determined using high-throughput sequencing of the internal transcribed spacer. Six grasslands were selected to represent different successional age classes: 0 (cropland), 5, 10, 15, 20, and 30 yr. Short-term decreases (initial 5 yr) in the amounts of soil organic carbon, total nitrogen, available phosphorus, and fungal biomass and in fungal diversity had returned to original levels (i.e., cropland) within 15 yr and were much higher after continued succession. Abandoning cropland for succession caused the soil erodibility (K) decrease and the aboveground coverage, soil nutrient levels, content of larger (>5 mm) water-stable aggregate, mean aggregate weight diameter, and diversity of the fungal communities improvement including arbuscular mycorrhizas (AMF), ectomycorrhizas (EMF), and saprotrophs. The fungal communities were dominated by Ascomycota, Zygomycota, Basidiomycota, and Glomeromycota during the succession. The successional patterns of the plant and fungal communities were similar, although distinct fungal communities were not observed in the two initial stages, suggesting that fungal succession may develop more slowly than plant succession. Plant root biomass, EMF, and soil organic carbon content accounted for most of the variation of soil erodibility (28.6%, 19.5%, and 11.8%, respectively), indicating their

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.

Assessment of toxic potency of complex mixtures of PAHs from Lincoln Creek, Milwaukee, WI

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

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

1995-12-31

An assay of cytochrome P4501A catalytic activity in PLHC-1 fish hepatoma cells was used to evaluate the toxic potency of dialysates from triolein filled semipermeable polymeric membrane devices (SPMDS) exposed for variable durations and under various flow regimes to water from Lincoln Creek. Toxic potency was expressed as 2,3,7,8 tetrachlorodibenzo-p-dioxin equivalents (TCDD-EQ) calculated from bioassay results. Dose-dependent responses in measured ethoxyresorufin-o-deethylase (EROD) activity of PLHC-1 cells exposed to SPMD dialysates were shown. Toxic potency of dialysates, expressed as bioassay derived TCDD equivalents, increased with duration of SPMD exposure in Lincoln Creek from 2.0 pg/uL for a 2 day exposure tomore » 19.5 pg/uL for a 30 day exposure. This corresponded to an increase in dialysate polycyclic aromatic hydrocarbon (PAH) concentration from 8.82 ug/g after a 2 day exposure to 24.14 ug/g after 30 days. Dialysates from SPMDs exposed to Lincoln Creek stormflow had higher toxic potencies and total PAH concentrations than those exposed to baseflow only, These results suggest that levels of PAH contamination, particularly those associated with stormflow, in Lincoln Creek have potential to accumulate in fish to levels significant enough to elicit a measurable biological response (cytochrome P4501 A induction) at a potency level approaching 0.08% that of TCDD.« less

The potential acute and chronic toxicity of cyfluthrin on the soil model organism, Eisenia fetida.

PubMed

Li, Lingling; Yang, Da; Song, Yufang; Shi, Yi; Huang, Bin; Bitsch, Annette; Yan, Jun

2017-10-01

In this study, the acute (72h and 14 d) and chronic (28 d and 8 weeks) effects of cyfluthrin on earthworms were evaluated across different endpoints, which are mortality, growth, reproduction and enzyme activities. Cyfluthrin was rated as moderately toxic in 72-h filter paper test and low toxic in 14-day soil test. The exposure of earthworms to cyfluthrin-polluted soil for 8 weeks showed that growth of earthworms was inhibited by cyfluthrin, cocoon production and hatching were inhibited by 20-60mg/kg cyfluthrin. Moreover, 28-day soil test on the responses of enzymes associated with antioxidation and detoxification showed that the activities of catalase (CAT) and glutathione S- transferase (GST) were initially increased by cyfluthrin at 5-20mg/kg, but reduced at 30-60mg/kg, peroxidase (POD) was increased by 26-102% by cyfluthrin in the early period, except 5mg/kg on day 7, and ethoxyresorufin-O-deethylase (EROD) was increased by 29-335% by cyfluthrin after 3 days. Cyfluthrin degraded with a half-life of 24.8-34.8 d, showing the inconsistency between the continuous toxic responses of earthworms and degradation of cyfluthrin in soil. The variable responses of these indexes indicated that different level endpoints should be jointly considered for better evaluation of the environmental risk of contaminants in soil. Copyright © 2017 Elsevier Inc. All rights reserved.

Bond strength and interfacial morphology of orthodontic brackets bonded to eroded enamel treated with calcium silicate-sodium phosphate salts or resin infiltration.

PubMed

Costenoble, Aline; Vennat, Elsa; Attal, Jean-Pierre; Dursun, Elisabeth

2016-11-01

 To investigate the shear bond strength (SBS) of orthodontic brackets bonded to eroded enamel treated with preventive approaches and to examine the enamel/bracket interfaces.  Ninety-one brackets were bonded to seven groups of enamel samples: sound; eroded; eroded+treated with calcium silicate-sodium phosphate salts (CSP); eroded+infiltrated by ICON ® ; eroded+infiltrated by ICON ® and brackets bonded with 1-month delay; eroded+infiltrated by an experimental resin; and eroded+infiltrated by an experimental resin and brackets bonded with 1-month delay. For each group, 12 samples were tested in SBS and bond failure was assessed with the adhesive remnant index (ARI); one sample was examined using scanning electron microscopy (SEM).  Samples treated with CSP or infiltration showed no significant differences in SBS values with sound samples. Infiltrated samples followed by a delayed bonding showed lower SBS values. All of the values remained acceptable. The ARI scores were significantly higher for sound enamel, eroded, and treated with CSP groups than for all infiltrated samples. SEM examinations corroborated the findings.  Using CSP or resin infiltration before orthodontic bonding does not jeopardize the bonding quality. The orthodontic bonding should be performed shortly after the resin infiltration.

Using High-Resolution Comparison of Bedrock Properties and Channel Morphology to Empirically Characterize Erodibility in Fluvial Settings

NASA Astrophysics Data System (ADS)

Chilton, K.; Spotila, J. A.

2017-12-01

Bedrock erodibility exerts a primary control on landscape evolution and fluvial morphodynamics, but the relationships between erodibility and the many factors that influence it (rock strength, spacing and orientation of discontinuities, weathering susceptibility, erosive process, etc.) remain poorly defined. This results in oversimplification of erodibility in landscape evolution models, the primary example being the stream power incision model, which groups together factors which may influence erodibility into a single coefficient. There is therefore need to better define how bedrock properties influence erodibility and, in turn, channel form and evolution. This study seeks to deconvolve the relationships between bedrock material properties and erodibility by quantifying empirical relationships between substrate characteristics and bedrock channel morphology (slope, steepness index, width, form) at a high spatial resolution (5-10 m scale) in continuous and mixed alluvial-bedrock channels. We specifically focus on slowly eroding channels with minimal evidence for landscape transience, such that variations in channel morphology are mainly due to bedrock properties. We also use channels cut into sedimentary rock, which exhibit extreme variation (yet predictability and continuity) in discontinuity spacing. Here we present preliminary data comparing the morphology and bedrock properties of 1st through 4th order channels in the tectonically inactive Valley and Ridge province of the Appalachian Mountains, SW Virginia. Field surveys of channel slope, width, substrate, and form consist of 0.5 km long, continuous stream reaches through different intervals of tilted Paleozoic siliciclastic stratigraphy. Some surveys exhibit nearly complete bedrock exposure, whereas others are predominantly mixed, with localized bedrock reaches in high-slope knickzones. We statistically analyze relationships between fluvial morphology and lithology, strength (based on field and laboratory

Soil erodibility for water erosion: A perspective and Chinese experiences

USDA-ARS?s Scientific Manuscript database

Erodibility is a key indicator to evaluate soil’s susceptibility to erosion and crucial for predicting and evaluating soil loss and its environmental effects. This review aims to synthesize almost a century’s worth of research progress on the concept, indicators, and spatio-temporal variations of so...

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.

Mink biomagnification factors for dioxin-like compounds fed Saginaw Bay carp

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

Kubiak, T.J.; Tillitt, D.E.; Heaton, S.N.

1994-12-31

Diets containing 0, 10, 20 and 40% Saginaw Bay carp were fed to ranch mink to assess reproductive effects. All carp diets adversely affected reproduction. The diets and livers of the adult mink at the end of the study were chemically analyzed for planar halogenated hydrocarbons (PHHS) that induce aryl hydrocarbon hydroxylase (AHH)/ethoxyresorufin o-deethylase (EROD). Biomagnification factors (BMFS) from diets to mink livers were calculated. AHH and EROD-active PCB congeners uniformly magnified across diets except for PCB 126, which had higher magnification at lowest carp and control diets. PCB and PCDF congener magnification ranged from incalculable to 60-fold higher andmore » individual PCDDs ranged from incalculable to 165 times the diet. As expected from previous mammalian studies, 2378-TCDD magnified over an order of magnitude more than 2378-TCDF but by 4 to 5-fold less than 23478-PCDF. Based on dioxin equivalents theory and TEFS, PCB 126 ranked first in the liver residues of 2378-TCDD equivalents followed by PCB 105, 23478-PCDF and 2378-TCDD. Magnification factors allow for interpretation of relative exposure risks from certain wild forage species if wild mink liver concentrations are known. Conversely, knowledge of wild mink forage item concentrations allows for calculation of an estimated wild mink liver residue, when the concentration and dietary forage percentage are multiplied by the BMF. Therefore, BMFs can assist in the elucidation of relative risk of a population to these contaminants without necessarily having large numbers of mink samples, especially in habitats such as the Saginaw Bay area where mink and otter populations are presumed to be affected by high PHH contamination.« less

Predicting of soil erosion with regarding to rainfall erosivity and soil erodibility

NASA Astrophysics Data System (ADS)

Suif, Zuliziana; Razak, Mohd Amirun Anis Ab; Ahmad, Nordila

2018-02-01

The soil along the hill and slope are wearing away due to erosion and it can take place due to occurrence of weak and heavy rainfall. The aim of this study is to predict the soil erosion degree in Universiti Pertahanan Nasional Malaysia (UPNM) area focused on two major factor which is soil erodibility and rainfall erosivity. Soil erodibility is the possibilities of soil to detach and carried away during rainfall and runoff. The "ROM" scale was used in this study to determine the degree of soil erodibility, namely low, moderate, high, and very high. As for rainfall erosivity, the erosive power caused by rainfall that cause soil loss. A daily rainfall data collected from January to April was analyzed by using ROSE index classification to identify the potential risk of soil erosion. The result shows that the soil erodibilty are moderate at MTD`s hill, high at behind of block Lestari and Landslide MTD hill, and critical at behind the mess cadet. While, the highest rainfall erosivity was recorded in March and April. Overall, this study would benefit the organization greatly in saving cost in landslide protection as relevant authorities can take early measures repairing the most affected area of soil erosion.

Development of in vivo biotransformation enzyme assays for ecotoxicity screening: In vivo measurement of phases I and II enzyme activities in freshwater planarians.

PubMed

Li, Mei-Hui

2016-08-01

The development of a high-throughput tool is required for screening of environmental pollutants and assessing their impacts on aquatic animals. Freshwater planarians can be used in rapid and sensitive toxicity bioassays. Planarians are known for their remarkable regeneration ability but much less known for their metabolic and xenobiotic biotransformation abilities. In this study, the activities of different phase I and II enzymes were determined in vivo by directly measuring fluorescent enzyme substrate disappearance or fluorescent enzyme metabolite production in planarian culture media. For phase I enzyme activity, O-deethylation activities with alkoxyresorufin could not be detected in planarian culture media. By contrast, O-deethylation activities with alkoxycoumarin were detected in planarian culture media. Increases in 7-ethoxycoumarin O-deethylase (ECOD) activities was only observed in planarians exposed to 1μM, but not 10μM, β-naphthoflavone for 24h. ECOD activity was inhibited in planarians exposed to 10 and 100μM rifampicin or carbamazepine for 24h. For phase II enzyme activity, DT-diaphorase, arylsulfatases, uridine 5'-diphospho (UDP)-glucuronosyltransferase or catechol-O-methyltransferase activity was determined in culture media containing planarians. The results of this study indicate that freshwater planarians are a promising model organism to monitor exposure to environmental pollutants or assess their impacts through the in vivo measurement of phase I and II enzyme activities. Copyright © 2016. Published by Elsevier Inc.

Wind-Eroded Silicate as a Source of Hydrogen Peroxide on Mars

NASA Astrophysics Data System (ADS)

Bak, E. N.; Merrison, J. P.; Jensen, S. K.; Nørnberg, P.; Finster, K.

2014-07-01

Laboratory simulations show that wind-eroded silicate can be a source of hydrogen peroxide. The ubiquitous, fine-grained silicate dust might thus explain the oxidizing properties of the martian soil and affect the preservation of organic compounds.

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

Aryl hydrocarbon receptor function in early vertebrates:Inducibility of cytochrome P450 1A in agnathan and elasmobranch fish

USGS Publications Warehouse

Hahn, Mark E.; Woodin, Bruce R.; Stegeman, John J.; Tillitt, Donald E.

1998-01-01

The mammalian aryl hydrocarbon receptor (AHR) is a ligand-activated transcription factor that controls the expression of cytochrome P450 1A (CYP1A) genes in response to halogenated aromatic hydrocarbons such as 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). The natural ligand and normal physiologic function of this protein are as yet unknown. One approach to understanding AHR function and significance is to determine the evolutionary history of this receptor and of processes such as CYP1A induction that are controlled by the AHR in mammals. In these studies, AHR function was evaluated in representative cartilaginous fish (little skate, Raja erinacea) and jawless fish (sea lamprey, Petromyzon marinus and Atlantic hagfish, Myxine glutinosa), using CYP1A induction as a model AHR-dependent response. Treatment of skate with β-naphthoflavone (BNF) caused an 8-fold increase in hepatic ethoxyresorufin O-deethylase (EROD) activity as well as a 37-fold increase in the content of immunodetectable CYP1A protein. Evidence of CYP1A inducibility was also obtained for another cartilaginous fish, the smooth dogfish Mustelus canis. In contrast, hepatic EROD activity was not detected in untreated lamprey nor in lamprey treated with 3,3′,4,4′-tetrachlorobiphenyl (TCB), a potent AHR agonist in teleosts. A possible CYP1A homolog was detected in lamprey hepatic microsomes by one of three antibodies to teleost CYP1A, but expression of this protein was not altered by TCB treatment. CYP1A protein and catalytic activity were measurable in hagfish, but neither was induced after treatment with TCB. These results suggest that the AHR-CYP1A signal transduction pathway is highly conserved in gnathostomes, but that there may be fundamental differences in AHR signaling or AHR-CYP1A coupling in agnathan fish. Agnathan fish such as hagfish and lamprey may be interesting model species for examining possible ancestral AHR functions not related to CYP1A regulation.

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.

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

USDA-ARS?s Scientific Manuscript database

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...

Effects of vegetation and fecal pellets on the erodibility of cohesive sediments: Ganghwa tidal flat, west coast of Korea.

PubMed

Ha, Ho Kyung; Ha, Hun Jun; Seo, Jun Young; Choi, Sun Min

2018-06-04

Although the Korean tidal flats in the Yellow Sea have been highlighted as a typical macrotidal system, so far, there have been no measurements of the sediment erodibility and critical shear stress for erosion (τ ce ). Using the Gust erosion microcosm system, a series of field experiments has been conducted in the Ganghwa tidal flat to investigate quantitatively the effects of biogenic materials on the erodibility of intertidal cohesive sediments. Four representative sediment cores with different surficial conditions were analyzed to estimate the τ ce and eroded mass. Results show that τ ce of the "free" sediment bed not covered by any biogenic material on the Ganghwa tidal flat was in the range of 0.1-0.2 Pa, whereas the sediment bed partially covered by vegetation (Phragmites communis) or fecal pellets had enhanced τ ce up to 0.45-0.6 Pa. The physical presence of vegetation or fecal pellets contributed to protection of the sediment bed by blocking the turbulent energy. An inverse relationship between the organic matter included in the eroded mass and the applied shear stress was observed. This suggests that the organic matter enriched in a near-bed fluff layer is highly erodible, and the organic matter within the underlying sediment layer becomes depleted and less erodible with depth. Our study underlines the role of biogenic material in stabilizing the benthic sediment bed in the intertidal zone. Copyright © 2018 Elsevier Ltd. All rights reserved.

Generation of Tg(cyp1a:gfp) Transgenic Zebrafish for Development of a Convenient and Sensitive In Vivo Assay for Aryl Hydrocarbon Receptor Activity.

PubMed

Xu, Hongyan; Li, Caixia; Li, Yan; Ng, Grace Hwee Boon; Liu, Chunsheng; Zhang, Xiaoyan; Gong, Zhiyuan

2015-12-01

Both dioxins/dioxin-like compounds and polycyclic aromatic hydrocarbons (PAHs) are persistent organic pollutants and cause multiple adverse health effects on human and wildlife. Cyp1a is the most commonly used biomarker induced by these pollutants through activation of the aryl hydrocarbon receptor (AhR) pathway. Here we generated Tg(cyp1a:gfp) transgenic zebrafish for establishing a convenient in vivo assay for analysing these xenobiotic compounds. The Tg(cyp1a:gfp) larvae at 4 day post-fertilization were tested with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), and GFP induction was observed mainly in the kidney, liver and gut. Similar GFP expression was also induced strongly by two dioxin-like chemicals, co-planar polychlorinated biphenyl (PCB126) and polychlorinated dibenzo-p-furan (PeCDF) and relatively weakly by two PAHs, 3-methylcholanthrene (3-MC) and benzo[a]pyrene (BAP). The lowest observed effective concentration (LOEC) of TCDD was estimated to be ∼1 pM and the EC50 (effective concentration to induce GFP in 50 % of Tg(cyp1a:gfp) larvae) was ∼10 pM. PCB126 and PeCDF had ∼10× lower potencies in GFP induction than TCDD, while the potencies for 3-MC and BAP were at least 1000× lower. The sensitivity of Tg(cyp1a:gfp) larvae to respond TCDD was also favourable compared to that of ethoxyresorufin-O-deethylase (EROD) assay in both zebrafish larvae and adult livers. As GFP-based assay in transgenic zebrafish can be easily accommodated in multi-well dishes, the Tg(cyp1a:gfp) zebrafish should provide not only a valuable biomonitoring tool for aquatic contaminants but also a potential high-throughput chemical screening platform for identification of new AhR agonists.

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.

Abrasion of eroded and sound enamel by a dentifrice containing diamond abrasive particles

PubMed

Wegehaupt, Florian J.; Hoegger, Vanessa G. M.; Attin, Thomas

2017-07-24

Eroded enamel is more susceptible to abrasive wear than sound enamel. New toothpastes utilizing diamond particles as abrasives have been developed. The present study investigated the abrasive wear of eroded enamel by three commercially available toothpastes (one containing diamond particles) and compared it to the respective wear of sound enamel caused by these toothpastes. Seventy-two bovine enamel samples were randomly allocated to six groups (S1–S3 and E1–E3; n=12). Samples were submitted to an abrasive (S1–S3) or erosion plus abrasion (E1–E3) cycling. Per cycle, all samples were brushed (abrasion; 20 brushing stokes) with the following toothpastes: S1/E1: Signal WHITE SYSTEM, S2/E2: elmex KARIESSCHUTZ and S3-E3: Candida WHITE DIAMOND (diamond particles). Groups E1–E3 were additionally eroded with HCl (pH 3.0) for 2 min before each brushing procedure. After 30, 60 and 90 cycles enamel wear was measured by surface profilometry. Within the same toothpaste and same number of cycles, enamel wear due to erosion plus abrasion was significantly higher than due to mere abrasion. After 30, 60 and 90 cycles, no significant difference in the wear in groups S1 and S2 was observed while the wear in group E1 was significantly (p<0.05, ANOVA, Scheffecyc) lower than that in group E2. After 90 cycles, wear in group S3 was about 5 times higher than that in group S2, while wear in group E3 was about 1.3 times higher than that in group E2. As compared to the other two investigated toothpastes, the dentifrice containing diamond particles caused slightly higher abrasive wear of eroded enamel and distinctly higher wear of sound enamel compared to the conventional toothpastes under investigation.

Seasonal change of WEPP erodibility parameters on a fallow plot

Treesearch

D. K. McCool; S. Dun; J. Q. Wu; W. J. Elliot

2011-01-01

In cold regions, frozen soil has a significant influence on runoff and water erosion. Frozen soil can reduce infiltration capacity, and the freeze-thaw processes degrade soil cohesive strength and increase soil erodibility. In the Inland Pacific Northwest of the USA, major erosion events typically occur during winter from low-intensity rain, snowmelt, or both as frozen...

Initial ecosystem restoration in the highly erodible Kisatchie Sandstone Hills

Treesearch

D. Andrew Scott

2014-01-01

Restoration of the unique and diverse habitats of the Kisatchie Sandstone Hills requires the re-introduction of fire to reduce fuel accumulation and promote herbaceous vegetation, but some soils in the area are extremely erodible, and past fires have resulted in high erosion rates. Overstory and understory vegetation, downed woody fuels, and other stand attributes were...

Short-term Morphodynamics of an Eroding Salt Marsh Shoreline in the Delaware Estuary, USA

NASA Astrophysics Data System (ADS)

Fanta, D.; Quirk, T. E.

2017-12-01

Marsh edge morphology can change rapidly through erosional and depositional processes. Along seemingly similar stretches of marsh shoreline, erosion processes and rates can vary dramatically. In the Delaware Estuary, annual rates of edge erosion vary from a few centimeters to several meters across relatively short stretches of shoreline. Differences in erosion processes observed here include areas with and without vegetation growth seaward of the eroding marsh scarp. To better understand the factors that influence changes in marsh edge morphology, we examined wave energy, marsh scarp profile, and vegetation structure in relation to lateral erosion and accretion along two stretches of the Delaware Estuary for two years. Rates of erosion ranged from 0.01 to over 7 m/yr depending on shoreline exposure to waves and location on marsh scarp depth profile. Sediment deposition and accretion were up to an order of magnitude higher 15 cm from the marsh edge than 5 cm from the marsh edge, and were driven by storm events. In some areas, vegetation persisted seaward of eroding marshes where wave activity was dampened by a shallower bathymetric profile. Wave energy, distance from the edge and marsh elevation all contributed to vegetation structure, and therefore sedimentation and accretion dynamics. These results highlight the interactive nature of biophysical processes leading to lateral retreat or potential resilience of marsh edges.

Geomorphology and forest management in New Zealand's erodible steeplands: An overview

NASA Astrophysics Data System (ADS)

Phillips, Chris; Marden, Michael; Basher, Les R.

2018-04-01

In this paper we outline how geomorphological understanding has underpinned forest management in New Zealand's erodible steeplands, where it contributes to current forest management, and suggest where it will be of value in the future. We focus on the highly erodible soft-rock hill country of the East Coast region of North Island, but cover other parts of New Zealand where appropriate. We conclude that forestry will continue to make a significant contribution to New Zealand's economy, but several issues need to be addressed. The most pressing concerns are the incidence of post-harvest, storm-initiated landslides and debris flows arising from steepland forests following timber harvesting. There are three areas where geomorphological information and understanding are required to support the forest industry - development of an improved national erosion susceptibility classification to support a new national standard for plantation forestry; terrain analysis to support improved hazard and risk assessment at detailed operational scales; and understanding of post-harvest shallow landslide-debris flows, including their prediction and management.

Isolated and mixed effects of diuron and its metabolites on biotransformation enzymes and oxidative stress response of Nile tilapia (Oreochromis niloticus).

PubMed

Felício, Andréia Arantes; Freitas, Juliane Silberschmidt; Scarin, Jéssica Bolpeti; de Souza Ondei, Luciana; Teresa, Fabrício Barreto; Schlenk, Daniel; de Almeida, Eduardo Alves

2018-03-01

Diuron is one of the most used herbicide in the world, and its field application has been particularly increased in Brazil due to the expansion of sugarcane crops. Diuron has often been detected in freshwater ecosystems and it can be biodegraded into three main metabolites in the environment, the 3,4-dichloroaniline (DCA), 3,4-dichlorophenylurea (DCPU) and 3,4-dichlorophenyl-N-methylurea (DCPMU). Negative effects under aquatic biota are still not well established for diuron, especially when considering its presence in mixture with its different metabolites. In this study, we evaluated the effects of diuron alone or in combination with its metabolites, DCPMU, DCPU and 3,4-DCA on biochemical stress responses and biotransformation activity of the fish Oreochromis niloticus. Results showed that diuron and its metabolites caused significant but dispersed alterations in oxidative stress markers and biotransformation enzymes, except for ethoxyresorufin-O-deethylase (EROD) activity, that presented a dose-dependent increase after exposure to either diuron or its metabolites. Glutathione S-transferase (GST) activity was significant lower in gills after exposure to diuron metabolites, but not diuron. Diuron, DCPMU and DCA also decreased the multixenobiotic resistance (MXR) activity. Lipid peroxidation levels were increased in gill after exposure to all compounds, indicating that the original compound and diuron metabolites can induce oxidative stress in fish. The integration of all biochemical responses by the Integrated Biomarker Response (IBR) model indicated that all compounds caused significant alterations in O. niloticus, but DCPMU caused the higher alterations in both liver and gill. Our findings imply that diuron and its metabolites may impair the physiological response related to biotransformation and antioxidant activity in fish at field concentrations. Such alterations could interfere with the ability of aquatic animals to adapt to environments contaminated by

Subacute effects of the brominated flame retardants hexabromocyclododecane and tetrabromobisphenol A on hepatic cytochrome P450 levels in rats.

PubMed

Germer, Silke; Piersma, Aldert H; van der Ven, Leo; Kamyschnikow, Andreas; Fery, Yvonne; Schmitz, Hans-Joachim; Schrenk, Dieter

2006-02-01

The brominated flame retardants tetrabromobisphenol A (TBBPA) and hexabromocyclododecane (HBCD) are found in the environment, e.g., in sediments and organisms, in food items, human blood samples and mother's milk. In this study, the effects of both compounds on rat hepatic cytochrome P450 (CYP) levels and activities were investigated. Juvenile/young male and female Wistar rats were treated orally with various doses via the feed (TBBPA) or by gavage (HBCD). After 28 days of treatment the animals were sacrificed and hepatic mRNA and microsomes were isolated. HBCD treatment led to a significant induction of CYP2B1 mRNA, CYP2B1/2B2 protein and 7-pentoxyresorufin O-depentylase (PROD) activity suggesting a phenobarbital-type of induction. Furthermore, a significant increase in CYP3A1/3A3 mRNA, CYP3A1 protein, and luciferin benzylether debenzylase (LBD) activity was found, being more pronounced in females than in males. The effect on CYP3A1/3A3 mRNA was significant in female rats at a daily dose of 3.0mg/kg body weight and above. HBCD exhibited no effects on CYP1A2 mRNA, CYP1A1/1A2 protein, or microsomal 7-ethoxyresorufin O-deethylase (EROD) activity suggesting lack of activation of the aryl hydrocarbon receptor. No significant effects on any of the parameters measured were obtained with TBBPA. Our findings suggest that oral exposure to HBCD induces drug-metabolising enzymes in rats probably via the CAR/PXR signalling pathway. Induction of CYPs and co-regulated enzymes of phase II of drug metabolism may affect homeostasis of endogenous substrates including steroid and thyroid hormones.

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

Genotoxic and enzymatic effects of fluoranthene in microsomes and freshly isolated hepatocytes from sole (Solea solea).

PubMed

Wessel, N; Ménard, D; Pichavant-Rafini, K; Ollivier, H; Le Goff, J; Burgeot, T; Akcha, F

2012-02-01

The fluoranthene (Fluo) is one of the most abundant polycyclic aromatic hydrocarbons (PAHs) in human food and in marine compartments. However, the existing data on its genotoxicity is poor and controversial. The aim of this study was to assess in vitro the potential genotoxicity of Fluo in sole and its possible effect on CYP450 modulation. Freshly isolated hepatocytes were exposed for 24 h to a range of Fluo concentrations from 0.5 to 50 μM in both culture flasks and microplate wells. The ethoxyresorufin-O-deethylase (EROD) activity was measured as an indicator of the activity of the cytochrome P450 1A1 (CYP1A1). The genotoxic effects were evaluated by measuring both DNA strand breaks and DNA adducts by the alkaline comet assay and the postlabeling technique respectively. Calf thymus DNA was also exposed to Fluo in the presence of sole liver microsomes in order to check for Fluo DNA adduct formation. In sole hepatocytes, Fluo was shown to induce a decrease in the EROD activity in a concentration-dependent manner. A significant genotoxic effect was observed in terms of DNA strand breakage from an exposure concentration of 5 μM: despite a concentration-dependent effect was observed, it did not follow a linear dose-response. The response was similar whatever the way of exposure in flasks or in wells. One reproducible adduct was detected in the hepatocytes exposed to the highest concentrations of Fluo. The formation of Fluo adducts was confirmed by the detection of one reproducible adduct following in vitro exposure of calf thymus DNA to 100 and 200 μM of Fluo in the presence of sole microsomes. These results demonstrate the potential of sole hepatocytes to metabolize Fluo in 24 h into reactive species, able to induce genotoxicity by DNA strand breakage and DNA adduct formation. Moreover, a miniaturized cell exposure system was validated for further experiments using fewer amounts of hepatocytes and contaminants, and allowing exposure to PAH metabolites. Copyright �

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

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

Yang, Jie; Zhu, Jinyong; Chan, King Ming, E-mail:

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 ofmore » 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. - Highlights: • BDE-99 is an aryl hydrocarbon receptor (Ahr) agonist in zebrafish liver cell-line ZFL. • BDE-99 induced EROD activity, CYP1A and ugt1ab gene expression, in ZFL. • BDE-99 induced the pregnane X receptor (Pxr) luciferase reporter gene system in ZFL. • BDE-47 did not show any effects in ZFL to induce CYP1A, ugt1ab, and EROD. • BDE-47 and -99 showed no induction of Rxr and Pxr pathways in ZFL cells.« less

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.

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

Effect of water potential and void ratio on erodibility for agricultural soils

USDA-ARS?s Scientific Manuscript database

Soil erodibility has confounded researchers for decades. Difficulties arise with initiation of motion, pore-water status, physical, and perhaps biological, material properties and type of applied energy (i.e. rainfall, runoff, freeze/thaw, wind). Though specific tests have been developed to determin...

The Effect of SnCl2/AmF Pretreatment on Short- and Long-Term Bond Strength to Eroded Dentin

PubMed Central

Zumstein, Katrin; Peutzfeldt, Anne; Lussi, Adrian

2018-01-01

This study investigated the effect of SnCl2/AmF pretreatment on short- and long-term bond strength of resin composite to eroded dentin mediated by two self-etch, MDP-containing adhesive systems. 184 dentin specimens were produced from extracted human molars. Half the specimens (n = 92) were artificially eroded, and half were left untreated. For both substrates, half the specimens were pretreated with SnCl2/AmF, and half were left untreated. The specimens were treated with Clearfil SE Bond or Scotchbond Universal prior to application of resin composite. Microtensile bond strength (μTBS) was measured after 24 h or 1 year. Failure mode was detected and EDX was performed. μTBS results were statistically analyzed (α = 0.05). μTBS was significantly influenced by the dentin substrate (eroded < noneroded dentin) and storage time (24 h > 1 year; p < 0.0001) but not by pretreatment with SnCl2/AmF or adhesive system. The predominant failure mode was adhesive failure at the dentin-adhesive interface. The content of Sn was generally below detection limit. Pretreatment with SnCl2/AmF did not influence short- and long-term bond strength to eroded dentin. Bond strength was reduced after storage for one year, was lower to eroded dentin than to noneroded dentin, and was similar for the two adhesive systems.

Understory Responses to Fertilization to Eroded Kisatchie Soil in Louisiana

Treesearch

Ronald E. Thill; John C. Bellemore

1988-01-01

Responses of native vegetation growing on highly eroded Kisatchie soil to a May 1982 application of 672 kg/ha of 16-30-l 3 fertilizer were monitored on two sites through 1985. Herbage increased from 1,133 kg/ha on control plots to 4,956 kg/ha on fertilized plots by August of the first year. Litter accumulations on treated plots provided excellent soil protection...

Xenobiotic metabolizing enzyme activities in cells used for testing skin sensitization in vitro.

PubMed

Fabian, E; Vogel, D; Blatz, V; Ramirez, T; Kolle, S; Eltze, T; van Ravenzwaay, B; Oesch, F; Landsiedel, R

2013-09-01

For ethical and regulatory reasons, in vitro tests for scoring potential toxicities of cosmetics are essential. A test strategy for investigating potential skin sensitization using two human keratinocytic and two human dendritic cell lines has been developed (Mehling et al. Arch Toxicol 86:1273–1295, 2012). Since prohaptens may be metabolically activated in the skin, information on xenobiotic metabolizing enzyme (XME) activities in these cell lines is of high interest. In this study, XME activity assays, monitoring metabolite or cofactor, showed the following: all three passages of keratinocytic (KeratinoSens® and LuSens) and dendritic (U937 und THP-1) cells displayed N-acetyltransferase 1 (NAT1) activities (about 6–60 nmol/min/mg S9-protein for acetylation of para-aminobenzoic acid). This is relevant since reactive species of many cosmetics are metabolically controlled by cutaneous NAT1. Esterase activities of about 1–4 nmol fluorescein diacetate/min/mg S9-protein were observed in all passages of investigated keratinocytic and about 1 nmol fluorescein diacetate/min/mg S9-protein in dendritic cell lines. This is also of practical relevance since many esters and amides are detoxified and others activated by cutaneous esterases. In both keratinocytic cell lines, activities of aldehyde dehydrogenase (ALDH) were observed (5–17 nmol product/min/mg cytosolic protein). ALDH is relevant for the detoxication of reactive aldehydes. Activities of several other XME were below detection, namely the investigated cytochrome P450-dependent alkylresorufin O-dealkylases 7-ethylresorufin O-deethylase, 7-benzylresorufin O-debenzylase and 7-pentylresorufin O-depentylase (while NADPH cytochrome c reductase activities were much above the limit of quantification), the flavin-containing monooxygenase, the alcohol dehydrogenase as well as the UDP glucuronosyl transferase activities.

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. © 2016 SETAC.

A multi-biomarker approach in scallop Chlamys farreri to assess the impact of contaminants in Qingdao coastal area of China.

PubMed

Guo, Ruiming; Pan, Luqing; Ji, Rongwang

2017-08-01

A multi-biomarker approach was carried out to classify the environmental quality and the adverse effects of contaminants on scallop Chlamys farreri. The scallops were collected from three sampling stations in Qingdao coastal area of China in March, May, August and October of 2015. A suite of environmental factors and biomarkers, including temperature, salinity, pH, the concentrations of polycyclic aromatic hydrocarbons (PAHs), tetrabromobisphenol A (TBBPA) and metals (Cr, Mn, Cu, Zn, Cd, Pb, As) in seawater and soft tissue, mRNA expression of aryl hydrocarbon receptor (AhR) and P-glycoprotein (P-gp), 7-ethoxyresorufin O-deethylase (EROD), glutathione-S-transferase (GST), uridine-diphosphate-glucuronyl-transferase (UGT), sulfotransferase (SULT), metallothionein (MT), Superoxide dismutase (SOD), glutathione peroxidase (GPx), catalase (CAT), lipid peroxidation (LPO) and protein carbonyl (PC) contents and DNA strand breaks, were measured in the gill and digestive gland. The results showed that S2 was the most polluted while S1 was identified the least polluted. Despite the differentiation of pollution levels and environmental parameters the selected biomarkers responded efficiently to contaminants. Principal component analysis (PCA) revealed that EROD for PAHs, AhR for TBBPA, MT for Cr, Pb and Mn, LPO and PC for Zn were the effective biomarkers respectively. This study demonstrated that the application of multi-biomarker approach in conjunction with the traditional analysis of environmental parameters and contaminants provided valuable information in environmental risk assessment. Copyright © 2017 Elsevier Inc. All rights reserved.

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.

Helium in the eroding atmosphere of an exoplanet.

PubMed

Spake, J J; Sing, D K; Evans, T M; Oklopčić, A; Bourrier, V; Kreidberg, L; Rackham, B V; Irwin, J; Ehrenreich, D; Wyttenbach, A; Wakeford, H R; Zhou, Y; Chubb, K L; Nikolov, N; Goyal, J M; Henry, G W; Williamson, M H; Blumenthal, S; Anderson, D R; Hellier, C; Charbonneau, D; Udry, S; Madhusudhan, N

2018-05-01

Helium is the second-most abundant element in the Universe after hydrogen and is one of the main constituents of gas-giant planets in our Solar System. Early theoretical models predicted helium to be among the most readily detectable species in the atmospheres of exoplanets, especially in extended and escaping atmospheres 1 . Searches for helium, however, have hitherto been unsuccessful 2 . Here we report observations of helium on an exoplanet, at a confidence level of 4.5 standard deviations. We measured the near-infrared transmission spectrum of the warm gas giant 3 WASP-107b and identified the narrow absorption feature of excited metastable helium at 10,833 angstroms. The amplitude of the feature, in transit depth, is 0.049 ± 0.011 per cent in a bandpass of 98 angstroms, which is more than five times greater than what could be caused by nominal stellar chromospheric activity. This large absorption signal suggests that WASP-107b has an extended atmosphere that is eroding at a total rate of 10 10 to 3 × 10 11 grams per second (0.1-4 per cent of its total mass per billion years), and may have a comet-like tail of gas shaped by radiation pressure.

Helium in the eroding atmosphere of an exoplanet

NASA Astrophysics Data System (ADS)

Spake, J. J.; Sing, D. K.; Evans, T. M.; Oklopčić, A.; Bourrier, V.; Kreidberg, L.; Rackham, B. V.; Irwin, J.; Ehrenreich, D.; Wyttenbach, A.; Wakeford, H. R.; Zhou, Y.; Chubb, K. L.; Nikolov, N.; Goyal, J. M.; Henry, G. W.; Williamson, M. H.; Blumenthal, S.; Anderson, D. R.; Hellier, C.; Charbonneau, D.; Udry, S.; Madhusudhan, N.

2018-05-01

Helium is the second-most abundant element in the Universe after hydrogen and is one of the main constituents of gas-giant planets in our Solar System. Early theoretical models predicted helium to be among the most readily detectable species in the atmospheres of exoplanets, especially in extended and escaping atmospheres1. Searches for helium, however, have hitherto been unsuccessful2. Here we report observations of helium on an exoplanet, at a confidence level of 4.5 standard deviations. We measured the near-infrared transmission spectrum of the warm gas giant3 WASP-107b and identified the narrow absorption feature of excited metastable helium at 10,833 angstroms. The amplitude of the feature, in transit depth, is 0.049 ± 0.011 per cent in a bandpass of 98 angstroms, which is more than five times greater than what could be caused by nominal stellar chromospheric activity. This large absorption signal suggests that WASP-107b has an extended atmosphere that is eroding at a total rate of 1010 to 3 × 1011 grams per second (0.1-4 per cent of its total mass per billion years), and may have a comet-like tail of gas shaped by radiation pressure.

The role of biomarkers to assess oil-contaminated sediment quality using toxicity tests with clams and crabs.

PubMed

Morales-Caselles, Carmen; Martín-Díaz, María Laura; Riba, Inmaculada; Sarasquete, Carmen; Delvalls, Tomás Angel

2008-06-01

A 28-d bioassay was conducted with two invertebrate species with different feeding habits, the clam Ruditapes philippinarum and the shore crab Carcinus maenas. The purpose of the present study was to assess the quality of sediments affected by oil spills in different areas of the Spanish coast. The organisms were exposed to environmental samples of oil-contaminated sediments during four weeks and, after the experiment, a suite of biomarkers of exposure was measured: The phase one detoxification system was assessed by ethoxyresorufin-O-deethylase (EROD) activity; glutathione-S-transferase (GST) is a phase-two detoxification enzyme but also is implicated in oxidative stress events; glutathione peroxidase (GPX), glutathione reductase (GR), and the ferric reducing ability of plasma (FRAP) assay were analyzed to determine the antioxidant activity of the tissues. The biomarker results were correlated with the chemical compounds bound to sediments (polycyclic aromatic hydrocarbons [PAHs], polychlorinated biphenyls [PCBs], Zn, Cd, Pb, Cu, Ni, Co, V) and a principal component analysis was carried out with the purpose of linking all the variables and to detect those contaminated sediments potentially harmful to the biota. Results showed induction of biomarkers in both invertebrate species and significant differences (p < 0.05; p < 0.01) were established among sediments affected by different spills. The use of the selected biomarkers together with the sediment chemical analysis assesses the bioavailability of contaminants and has proven to be a suitable tool to monitor the environmental quality of sediments affected by oil spills.

Effects on Biotransformation, Oxidative Stress, and Endocrine Disruption in Rainbow Trout (Oncorhynchus mykiss) Exposed to Hydraulic Fracturing Flowback and Produced Water.

PubMed

He, Yuhe; Folkerts, Erik J; Zhang, Yifeng; Martin, Jonathan W; Alessi, Daniel S; Goss, Greg G

2017-01-17

The effects of hydraulic fracturing (HF) flowback and produced water (HF-FPW), a complex saline mixture of injected HF fluids and deep formation water that return to the surface, was examined in rainbow trout (Oncorhynchus mykiss). Exposure to HF-FPWs resulted in significant induction of ethoxyresorufin-O-deethylase (EROD) activity in both liver and gill tissues. Increased lipid peroxidation via oxidative stress was also detected by thiobarbituric acid reactive substances (TBARS) assay. The mRNA expressions of a battery of genes related to biotransformation, oxidative stress, and endocrine disruption were also measured using quantitative real-time polymerase chain reaction (Q-RT-PCR). The increased expression of cyp1a (2.49 ± 0.28-fold), udpgt (2.01 ± 0.31-fold), sod (1.67 ± 0.09-fold), and gpx (1.58 ± 0.10-fold) in raw sample exposure group (7.5%) indicated elevated metabolic enzyme activity, likely through the aryl hydrocarbon receptor pathway, and generation of reactive oxygen species. In addition, the elevated vtg and era2 expression demonstrated endocrine disrupting potential exerted by HF-FPW in rainbow trout. The overall results suggested HF-FPW could cause significant adverse effects on fish, and the organic contents might play the major role in its toxicity. Future studies are needed to help fully determine the toxic mechanism(s) of HF-FPW on freshwater fish, and aid in establishing monitoring, treatment, and remediation protocols for HF-FPW.

Experimental simulation of gravity currents in erodible bed

NASA Astrophysics Data System (ADS)

Bateman, A.; La Roca, M.; Medina, V.

2009-04-01

Gravity currents are commonly met in nature, when a flow of denser fluid moves into a less dense one. A typical example of a gravity current is given by the sea water which flows into the bottom of a river during the summer, in correspondence of the estuary, when the river's discharge attains low values. In this case, dangerous consequences can occur, because of the polluting of the aquifer caused by the salty water. Density currents also occurs in lakes and reservoirs, because of a change in temperature or because a flood, both can produce some environmental impacts that are of interest to the local water Agency of the different countries. Of particular relevance is also the interaction of the gravity current with the movement of the sediments from the bottom of the bed. The international state of the art is particularly concerned with experimental and numerical investigation on gravity currents on fixed and porous bed [1-2-3], while, to the authors' knowledge, the interaction of a gravity current with an erodible bed is still an open field of investigation. In this paper experiments concerning with the propagation of a gravity current over fixed and erodible bed are presented. The experiments, conducted at the laboratory of Hydraulics of the Universitat Politecnica de Catalunya (actually in the Prof. Bateman's blue room), were concerned with a transparent tank 2 m long, 0.2 m wide and 0.3 m deep, partly filled with salty water and partly with fresh water, up to a depth of 0.28 m. The salty water, whose density was in the range 1050erodible bed. In this latter case a homogeneous sand (d50=0.3 mm) was used. The results, concerned with the visualisation of the flow and the measurement of the wave front velocity, were obtained. Also the size and the frequency of the new vortices

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

Yield potential and nitrogen requirements of Miscanthus × giganteus on eroded soil

USDA-ARS?s Scientific Manuscript database

Miscanthus × giganteus yield and fertilizer N requirements have been well studied in Europe and parts of the United States, but few reports have investigated its production on eroded claypan soils economically marginal for grain crops. This study was conducted to evaluate yield potential and fertili...

Investigating the Effect of Compaction Characteristics on the Erodibility of Cohesive Soils Using the JET Method

NASA Astrophysics Data System (ADS)

Asghari Tabrizi, A.; LaRocque, L. A.; Chaudhry, M.; Imran, J.

2013-12-01

Several flood disasters occur every year all over the world, mostly due to levee and dam failure which result in human fatalities as well as devastating economic damages. To model and predict earthen embankment failures for the preparation of emergency action plans and risk assessments, the soil erodibility by flowing water is an essential parameter. The determination of erodibility becomes even more complicated for cohesive soils because of the large number of parameters controlling their erosion behavior (e.g. clay content, plasticity, compaction effort, compaction water content) and the difficulty of estimating these parameters. In this study the effect of the compaction energy and compaction water content on the erodibility of a sandy loam soil was assessed. Soil samples were prepared in a standard diameter compaction mold, 101.6 mm, for three levels of compaction effort and water content (i.e. low, medium, and high) with two replications for each case (18 tests total) and examined using the jet erosion test (JET). Observations from qualitative and statistical analyses of the data are: 1) a wide range of erodibility, from very erodible to very resistant, was produced by changes in the compaction characteristics; 2) for a given compaction energy, the erosion resistance based on the detachment rate coefficient kd tends to become minimum near the optimum compaction water content. On the dry side of optimum compaction water content, kd decreases with steep gradients by increasing the water content, while it increases with a flatter gradient on the wet side; 3) At a given water content, the soil erosion resistance increases with compaction efforts; 4) compaction water content influences soil erosibility more than compaction energy, especially on the dry side of the optimum compaction water content; and 5) for a given compaction effort, the critical shear stress increases with water content up to an optimum water content and then it decreases which is in consistent

Determining Relative Contributions of Eroded Landscape Sediment and Bank Sediment to the Suspended Load of Streams and Wetlands Using 7Be and 210Pbxs

NASA Astrophysics Data System (ADS)

Wilson, C.; Matisoff, G.; Whiting, P.; Kuhnle, R.

2005-12-01

The naturally occurring radionuclides, 7Be and 210Pbxs, have been used individually as tracers of sediment particles throughout watersheds. However, use of the two radionuclides together enables eliciting information regarding the major contributors of fine sediment to the suspended load of a stream or wetland. We report on a study that uses these radionuclides to quantify the relative proportion of eroded surface soils, bank material and resuspended bed sediment in the fine suspended sediment load of the Goodwin Creek, MS, and Old Woman Creek, OH watersheds. The eroded surface soil has a unique radionuclide signature relative to the bed sediments in Old Woman Creek and the bank material along Goodwin Creek that allows for the quantification of the relative proportions of the different sediments in the sediment load. In Old Woman Creek, the different signatures are controlled by the differential decay of the two radionuclides. In Goodwin Creek, the different signatures are due to different erosion processes controlling the sediment delivery to streams, namely sheet erosion and bank collapse. The eroded surface soils will have higher activities of the 7Be and 210Pbxs than bed/bank sediments. The fine suspended sediment, which is a mixture of eroded surface soils and resuspended bed sediment or collapsed bank sediment, will have an intermediate radionuclide signature quantified in terms of the relative proportion from both sediments. A simple two-end member mixing model is used to determine the relative proportions of both sediments to the total fine sediment load.

The StreamCat Dataset: Accumulated Attributes for NHDPlusV2 Catchments (Version 2.1) for the Conterminous United States: Soil Erodibility (KFFACT)

EPA Pesticide Factsheets

This dataset represents the adjusted soil erodibility factor within individual, local NHDPlusV2 catchments and upstream, contributing watersheds. Attributes of the landscape layer were calculated for every local NHDPlusV2 catchment and accumulated to provide watershed-level metrics. (See Supplementary Info for Glossary of Terms) The STATSGO Layer table specifies two soil erodibility factors for each component layer, KFFACT and KFACT. The STATSGO documentation describes KFFACT as a soil erodibility factor which quanitifies the susceptibility of soil particles to detachment and movement by water. This factor is used in the Universal Soil Loss Equation to caluculate soil loss by water. KFACT is described as a soil erodibility factor which is adjusted for the effect of rock fragments. The average value of each of these soil erodibility factors was determined for the top (surface) layer for each map unit of each state.The base-flow index (BFI) grid for the conterminous United States was developed to estimate (1) BFI values for ungaged streams, and (2) ground-water recharge throughout the conterminous United States (see Data Source). Estimates of BFI values at ungaged streams and BFI-based ground-water recharge estimates are useful for interpreting relations between land use and water quality in surface and ground water. The soil erodibility factor was summarized by local catchment and by watershed to produce local catchment-level and watershed-level metri

Effect of erodent particles on the erosion of metal specimens

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

Razzaque, M. Mahbubur, E-mail: mmrazzaque@me.buet.ac.bd; Alam, M. Khorshed; Khan, M. Ishak, E-mail: ishak.buet@gmail.com

2016-07-12

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 aremore » 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.« less

In vivo effects of environmental concentrations of produced water on the reproductive function of polar cod (Boreogadus saida).

PubMed

Geraudie, P; Nahrgang, J; Forget-Leray, J; Minier, C; Camus, L

2014-01-01

Offshore oil and gas drilling processes generate operational discharges such as produced water (PW), a complex mixture of seawater with polycyclic aromatic hydrocarbons (PAH) and alkylphenols (AP). Some of these compounds may interact with the endocrine system of marine organisms and alter reproductive functions. In this study, polar cod were exposed for up to 28 d to a mixture of PAH, alkylated PAH, and AP simulating the composition of North Sea PW, at low and high concentrations (1:2000 and 1:1000 dilution of the original concentrate, respectively). Potential adverse effects of PW on polar cod physiology were investigated through biomarkers of biotransformation (hepatic ethoxyresorufin O-deethylase [EROD] activity and bile PAH metabolites), endocrine disruption (plasma vitellogenin [VTG] levels and sex steroid concentrations), and gonad histology. Plasma sexual steroid levels in fish were not markedly affected by PW exposure, while higher plasma VTG concentrations were measured in females exposed to the high PW treatment for 7 and 28 d. In males exposed to the higher PW concentration, inhibition of spermatogenesis was observed after 28 d in addition to increase of melano-macrophage occurrence in testis. Females exposed to the high PW treatment for 21 d showed a significant increase of atresia incidence. Finally, a significant decrease in oocyte number was observed in high PW exposed female ovaries after 28 d of exposure.

Rock Erodibility as a Dynamic Variable Driven by the Interplay between Erosion and Weathering in Bedrock Channels: Examples from Great Falls, Virginia, USA

NASA Astrophysics Data System (ADS)

Hancock, G. S.; Huettenmoser, J.; Shobe, C. M.; Eppes, M. C.

2016-12-01

Rock erodibility in channels is a primary control on the stresses required to erode bedrock (e.g., Sklar and Dietrich, 2001). Erodibility tends to be treated as a uniform and fixed variable at the scale of channel cross-sections, particularly in models of channel profile evolution. Here we present field data supporting the hypothesis (Hancock et al., 2011) that erodibility is a dynamic variable, driven by the interplay between erosion rate and weathering processes within cross-sections. We hypothesize that rock weathering varies in cross-sections from virtually unweathered in the thalweg, where frequent stripping removes weathered rock, to a degree of weathering determined by the frequency of erosive events higher on the channel margin. We test this hypothesis on three tributaries to the Potomac River underlain by similar bedrock but with varying erosion rates ( 0.01 to 0.8 m/ky). At multiple heights within three cross-sections on three tributaries, we measured compressive strength with a Schmidt hammer, surface roughness with a contour gage, and density and length of visible cracks. Compressive strength decreased with height in all nine cross-sections by 10% to 50%, and surface roughness increased with height in seven cross-sections by 25% - 45%, with the remaining two showing minimal change. Crack density increased with height in the three cross-sections measured. Taken together these data demonstrate increases in weathering intensity, and presumably, rock erodibility, with height. The y-intercept of the relation between height and the three measured variables were nearly identical, suggesting that thalweg erodibility was similar on each channel, as predicted, even though erodibility higher in the cross-section were markedly different. The rate at which the three variables changed with height in each cross-section is strongly related to stream power. Assuming stream power is a reasonable surrogate for erosion rate, this result implies that erosion rate can be a

Ecological risk assessment in a large river-reservoir. 8: Experimental study of the effects of polychlorinated biphenyls on reproductive success in mink

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

Halbrook, R.S.; Aulerich, R.J.; Bursian, S.J.

1999-04-01

As a component of an ecological risk assessment of Poplar Creek (located on the Oak Ridge Reservation [ORR]) and the Clinch River (a large river-reservoir system), fish from Poplar Creek, the Clinch River, and Atlantic Ocean were fed to ranch mink to evaluate reproductive success. Five diets, each composed of 75% fish and 25% normal ranch mink chow, were prepared. Two diets served as reference diets and contained 75% Atlantic Ocean fish or 75% Clinch River fish collected above the ORR. The fish portion of the remaining three diets contained 25, 50, and 75% fish collected from Poplar Creek andmore » 50, 25, and 0% ocean fish, respectively. Five mink groups (eight females and two males each) were each fed one of the prepared diets for 196 days. Polychlorinated biphenyl concentrations were determined in diets and various mink tissues, ethoxyresorufin-O-deethylase (EROD) activity was determined in liver tissue, and reproductive success was evaluated. Concentrations of PCB were greatest in the diet composed of 75% Poplar Creek fish and in tissues from mink fed this diet and their offspring. There was a trend toward decreased adult female and kit weights and reduced mean litter size in mink fed diets containing 75% Poplar Creek fish; however, at 6 weeks of age, kit survival was similar among diet groups. Liver EROD activity significantly increased in adult female mink fed 50 and 75% Poplar Creek fish diets. Estimated dietary concentrations of PCBs were similar to or slightly lower than concentrations associated with adverse effects in experimentally dosed mink. Mercury (Hg) concentrations previously reported in these same mink were below that associated with adverse effects, and there was no indication of additive or synergistic effects from exposure to PCBs plus Hg. It is unlikely that population-level reproductive effects would be observed in mink consuming fish from Poplar Creek on the ORR.« less

Tracing the source of soil organic matter eroded from temperate forest catchments using carbon and nitrogen isotopes

DOE PAGES

McCorkle, Emma P.; Berhe, Asmeret Asefaw; Hunsaker, Carolyn T.; ...

2016-04-29

Here, soil erosion continuously redistributes soil and associated soil organic matter (SOM) on the Earth's surface, with important implications for biogeochemical cycling of essential elements and terrestrial carbon sequestration. Despite the importance of soil erosion, surprisingly few studies have evaluated the sources of eroded carbon (C). We used natural abundance levels of the stable and radioactive isotopes of C ( 13C and 14C) and stable isotope of nitrogen ( 15N) to elucidate the origins of SOM eroded from low-order catchments along the western slopes of the Sierra Nevada of California, USA. Our work was conducted in two relatively undisturbed catchmentsmore » (low elevation = 1800 m, and high elevation = 2300 m) of the Kings River Experimental Watersheds (KREW) in the Sierra National Forest. Sediment captured in basins at the outlet of each gauged watershed were compared to possible source materials, which included: upland surficial organic horizons (i.e., forest floor) and mineral soils (0–0.6 m) from three landform positions (i.e., crest, backslope, and toeslope), stream bank soils (0–0.6 m), and stream-bed materials (0–0.05 m). We found that most of the organic matter (OM) in the captured sediments was composed of O-horizon material that had high C concentrations. Radiocarbon analyses also showed that the captured OM is composed of modern (post-1950) C, with fraction modern values at or above 1.0. Our results suggest that surface (sheet) erosion, as opposed to channeling through established streams and episodic mass wasting events, is likely the largest source of sediment exported out of these minimally disturbed, headwater catchments. The erosional export of sediment with a high concentration of C, especially in the form of relatively undecomposed litter from the O horizon, suggests that a large fraction of the exported C is likely to be decomposed during or after erosion; hence, it is unlikely that soil erosion acts as a significant net sink

Tracing the source of soil organic matter eroded from temperate forest catchments using carbon and nitrogen isotopes

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

McCorkle, Emma P.; Berhe, Asmeret Asefaw; Hunsaker, Carolyn T.

Here, soil erosion continuously redistributes soil and associated soil organic matter (SOM) on the Earth's surface, with important implications for biogeochemical cycling of essential elements and terrestrial carbon sequestration. Despite the importance of soil erosion, surprisingly few studies have evaluated the sources of eroded carbon (C). We used natural abundance levels of the stable and radioactive isotopes of C ( 13C and 14C) and stable isotope of nitrogen ( 15N) to elucidate the origins of SOM eroded from low-order catchments along the western slopes of the Sierra Nevada of California, USA. Our work was conducted in two relatively undisturbed catchmentsmore » (low elevation = 1800 m, and high elevation = 2300 m) of the Kings River Experimental Watersheds (KREW) in the Sierra National Forest. Sediment captured in basins at the outlet of each gauged watershed were compared to possible source materials, which included: upland surficial organic horizons (i.e., forest floor) and mineral soils (0–0.6 m) from three landform positions (i.e., crest, backslope, and toeslope), stream bank soils (0–0.6 m), and stream-bed materials (0–0.05 m). We found that most of the organic matter (OM) in the captured sediments was composed of O-horizon material that had high C concentrations. Radiocarbon analyses also showed that the captured OM is composed of modern (post-1950) C, with fraction modern values at or above 1.0. Our results suggest that surface (sheet) erosion, as opposed to channeling through established streams and episodic mass wasting events, is likely the largest source of sediment exported out of these minimally disturbed, headwater catchments. The erosional export of sediment with a high concentration of C, especially in the form of relatively undecomposed litter from the O horizon, suggests that a large fraction of the exported C is likely to be decomposed during or after erosion; hence, it is unlikely that soil erosion acts as a significant net sink

Effect of surface protection on the permeability of eroded dentin

PubMed Central

Martins, Vivian Leite; da Costa Ramos, Rodrigo Vitoria; Pimenta Lima, Max José; Correia de Araújo, Roberto Paulo; Cavalcanti, Andrea Nóbrega

2018-01-01

Context: Eroded dentin might present the opening of dentinal tubules, increasing permeability, and consequently dentinal hypersensitivity. Aims: This study evaluated the permeability of dentin surfaces exposed to different levels of erosion and methods of surface protection. Materials and Methods: Dentine samples (3 mm × 3 mm × 1 mm) were prepared from bovine incisors (n = 90) and divided into three groups according to the method of controlling erosive challenge: Negative control, topical fluoride application, and glass ionomer sealant. Subsequently, they were randomly divided into three subgroups according to the exposure of simulated gastric acid solution (Demineralization – DES) (5% HCl, pH = 2.2), and remineralization (RE); negative control, 9 and 18 cycles DES-RE. The dentin permeability was measured by assessing the hydraulic conductance (μl/min.cmH2O.cm2). Statistical analysis was performed by two-way ANOVA and Tukey's test. Results and Conclusions: Greater permeability was observed after 18 erosive cycles, followed by exposure to 9 cycles and negative control (P < 0.0001). The application of glass ionomer sealant resulted in a major reduction of the hydraulic conductivity, regardless of the erosive challenge. Control groups and topical fluoride application showed similar results. In conclusion, the severity of erosive challenge contributed to the increase of dentin permeability. Besides, the glass ionomer sealant was the only protection agent that promoted significant effects in dentin permeability. PMID:29628641

The chlorinated AHR ligand 3,3′,4,4′,5-pentachlorobiphenyl (PCB126) promotes reactive oxygen species (ROS) production during embryonic development in the killifish (Fundulus heteroclitus)

USGS Publications Warehouse

Arzuaga, Xabier; Wassenberg, Deena; Giulio, Richard D.; Elskus, Adria

2006-01-01

Exposure to dioxin-like chemicals that activate the aryl hydrocarbon receptor (AHR) can result in increased cellular and tissue production of reactive oxygen species (ROS). Little is known of these effects during early fish development. We used the fish model, Fundulus heteroclitus, to determine if the AHR ligand and pro-oxidant 3,3′,4,4′,5-pentachlorobiphenyl (PCB126) can increase ROS production during killifish development, and to test a novel method for measuring ROS non-invasively in a living organism. The superoxide-sensitive fluorescent dye, dihydroethidium (DHE), was used to detect in ovo ROS production microscopically in developing killifish exposed to PCB126 or vehicle. Both in ovo CYP1A activity (ethoxyresorufin-o-deethylase, EROD) and in ovo ROS were induced by PCB126. In ovo CYP1A activity was inducible by PCB126 concentrations as low as 0.003 nM, with maximal induction occurring at 0.3 nM PCB126. These PCB126 concentrations also significantly increased in ovo ROS production in embryonic liver, ROS being detectable as early as 5 days post-fertilization. These data demonstrate that the pro-oxidant and CYP1A inducer, PCB126, increases both CYP1A activity and ROS production in developing killifish embryos. The superoxide detection assay (SoDA) described in this paper provides a semi-quantitative, easily measured, early indicator of altered ROS production that can be used in conjunction with simultaneous in ovo measurements of CYP1A activity and embryo development to explore functional relationships among biochemical, physiological and developmental responses to AHR ligands.

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.

Predicting the particle size distribution of eroded sediment using artificial neural networks.

PubMed

Lagos-Avid, María Paz; Bonilla, Carlos A

2017-03-01

Water erosion causes soil degradation and nonpoint pollution. Pollutants are primarily transported on the surfaces of fine soil and sediment particles. Several soil loss models and empirical equations have been developed for the size distribution estimation of the sediment leaving the field, including the physically-based models and empirical equations. Usually, physically-based models require a large amount of data, sometimes exceeding the amount of available data in the modeled area. Conversely, empirical equations do not always predict the sediment composition associated with individual events and may require data that are not always available. Therefore, the objective of this study was to develop a model to predict the particle size distribution (PSD) of eroded soil. A total of 41 erosion events from 21 soils were used. These data were compiled from previous studies. Correlation and multiple regression analyses were used to identify the main variables controlling sediment PSD. These variables were the particle size distribution in the soil matrix, the antecedent soil moisture condition, soil erodibility, and hillslope geometry. With these variables, an artificial neural network was calibrated using data from 29 events (r 2 =0.98, 0.97, and 0.86; for sand, silt, and clay in the sediment, respectively) and then validated and tested on 12 events (r 2 =0.74, 0.85, and 0.75; for sand, silt, and clay in the sediment, respectively). The artificial neural network was compared with three empirical models. The network presented better performance in predicting sediment PSD and differentiating rain-runoff events in the same soil. In addition to the quality of the particle distribution estimates, this model requires a small number of easily obtained variables, providing a convenient routine for predicting PSD in eroded sediment in other pollutant transport models. Copyright © 2017 Elsevier B.V. All rights reserved.

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

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

USDA-ARS?s Scientific Manuscript database

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...

Modifications of hepatic drug metabolizing enzyme activities in rats fed baobab seed oil containing cyclopropenoid fatty acids.

PubMed

Andrianaivo-Rafehivola, A A; Siess, M H; Gaydou, E M

1995-05-01

The effects on drug metabolizing enzymes of cyclopropenoid fatty acids present in baobab seed oil were evaluated in rats fed either a diet with baobab seed oil (1.27% cyclopropenoid fatty acids in the diet) or a diet with heated baobab seed oil (0.046% cyclopropenoid fatty acids in the diet). Comparison was made with rats fed a mixture of oils that contained no cyclopropenoid fatty acid. Rats fed baobab oil showed retarded growth. In comparison with the other groups, the relative liver weights were markedly increased whereas cytochrome P-450 content and NADPH cytochrome c reductase and NADH cytochrome c reductase activities were decreased. In rats fed the heated baobab oil the relative liver weight was decreased and the cytochrome P-450 level and reductase activities were increased relative to levels in rats fed the unheated oil. Ethoxycoumarin deethylase, ethoxyresorufin deethylase and pentoxyresorufin depentylase activities, expressed on the basis of cytochrome P-450, were greater in the group fed unheated baobab seed oil. Cytosolic glutathione transferase activity was markedly decreased in rats fed fresh baobab seed oil and heating the oil, which reduced the content of cyclopropenoid fatty acids, led to a considerable increase of this activity. UDP-glucuronyl transferase activities were not modified by the type of oil included in the diet. It is possible that the mechanisms of action of cyclopropenoid fatty acids are related to alterations of membrane lipid composition or microsomal proteins.

Effects of tillage and broiler litter on crop productions in an eroded soil

USDA-ARS?s Scientific Manuscript database

Soils in the southeastern United States, where the climate is subtropical, are severely eroded from intense row crop agriculture many years ago. This study was initiated in 2005 at the Plant Material Center, NRCS, in Coffeeville MS, on an Loring silt loam (fine-silty, mixed, thermic, Glossic Fragiud...

Induced cytochrome P450 1A activity in cichlid fishes from Guandu River and Jacarepaguá Lake, Rio de Janeiro, Brazil.

PubMed

Parente, Thiago E M; De-Oliveira, Ana C A X; Paumgartten, Francisco J R

2008-03-01

The induction of cytochrome P4501A-mediated activity (e.g. ethoxyresorufin-O-deethylation, EROD) has been used as a biomarker for monitoring fish exposure to AhR-receptor ligands such as polycyclic aromatic hydrocarbons (PAH), polychlorinated biphenyls (PCB) and polychlorinated dibenzo-dioxins/furans (PCDD/Fs). In this study we found that hepatic EROD is induced in fish ("Nile tilapia", Oreochromis niloticus and "acará", Geophagus brasiliensis) from the Guandu River (7-17-fold) and Jacarepaguá Lake (7-fold), Rio de Janeiro, Brazil. Since both cichlid fish are consumed by the local population and the Guandu River is the main source of the drinking water supply for the greater Rio de Janeiro metropolitan area, pollution by cytochrome P4501A-inducing chemicals is a cause for concern and should be further investigated in sediments, water and biota. We additionally showed that EROD activity in the fish liver post-mitochondrial supernatant-simpler, cheaper and less time consuming to prepare than the microsomal fraction-is sufficiently sensitive for monitoring purposes.

Biological responses to contaminants in darters (Etheostoma spp.) collected from rural and urban regions of the Grand River, ON, Canada.

PubMed

Diamond, Sam R; Sultana, Tamanna; Servos, Mark R; Metcalfe, Chris D

2016-09-01

Urban and agricultural activities may introduce chemical stressors, including contaminants of emerging concern (CECs) and current use pesticides (CUPs) into riverine systems. The objective of this study was to determine if fish collected from various sites in the Grand River, ON, Canada show biomarkers of exposure to these classes of contaminants, and if the biomarker patterns vary in fish collected from urbanized and agricultural sites. Female rainbow darters (Etheostoma caeruleum) and female fantail darters (Etheostoma flabellare) were collected from the Grand River in June, 2014 for biomarker analysis from two urbanized sites and three agricultural sites. Over the same period of time, Polar Organic Chemical Integrative Samplers (POCIS) were deployed for 2weeks at each site to monitor for the presence of CUPs and CECs. Data on the liver somatic index for darters indicate site-specific differences in this condition factor (p<0.05). Significant differences in the levels of thiobarbituric acid reactive substances (TBARS) in gill tissue (p<0.05) of darters collected from the various sites indicate site-specific differences in oxidative stress. The activities of ethoxyresorufin-O-deethylase (EROD) in the liver tissue of rainbow darters were significantly different between sites (p<0.05), indicating differences in exposure to chemicals that induce or inhibit CYP450 1A metabolic activity. Finally, acetylcholinesterase (AChE) activity in brain tissue was significantly different between rainbow darters collected from rural and urban sites (p<0.05). These data showing different impacts from chemical inputs related to land uses in the watershed may be useful in developing mitigation strategies to reduce impacts on fish and other aquatic organisms in receiving environments. Copyright © 2016. Published by Elsevier Inc.

Effects of acute and chronic exposures of fluoxetine on the Chinese fish, topmouth gudgeon Pseudorasbora parva.

PubMed

Chen, Hongxing; Zeng, Xiangfeng; Mu, Lei; Hou, Liping; Yang, Bin; Zhao, Jianliang; Schlenk, Daniel; Dong, Wu; Xie, Lingtian; Zhang, Qianru

2018-09-30

Fluoxetine is a selective serotonin reuptake inhibitor used as an antidepressant and has been frequently detected in aquatic environments. However, its effects in fish from Asia remain relatively less studied. In this study, the topmouth gudgeon Pseudorasbora parva was exposed to 0, 50, and 200 µg/L of fluoxetine for 4 h and 42 d. The effects of fluoxetine on biometrics were compared to biochemical endpoints indicative of stress in different fish tissues (brain, liver, gills and intestine) following exposures. In fish exposed for 42 d, lipid peroxidation endpoints were enhanced 80% in the liver and gills. Acetylcholinesterase (AChE) activity was increased 40% after exposure to 50 µg/L and 55% at 200 µg/L following 4 h exposure. In contrast AChE was increased 26% (at 50 µg/L) after 42 d of exposures. Enhanced ethoxyresorufin-O-deethylase activity (EROD) was detected only in fish exposed to 50 µg/L of fluoxetine for 4 h. The activity of α-glucosidase (α-Glu) was also induced (at 200 µg/L) after 4 h of exposure. After 4 h of exposure, the activities of proteases in the intestine were generally inhibited at 200 µg/L. Both 4 h and 42 d exposures resulted in an increased hepatosomatic index (HSI) but did not affect the condition factor (CF). Our results demonstrate that fluoxetine significantly altered biochemical endpoints in P. parva after acute exposure and the morphological changes in liver size were not observed until 42 d of exposure. Copyright © 2018. Published by Elsevier Inc.

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.

Eroding market stability by proliferation of financial instruments

NASA Astrophysics Data System (ADS)

Caccioli, F.; Marsili, M.; Vivo, P.

2009-10-01

We contrast Arbitrage Pricing Theory (APT), the theoretical basis for the development of financial instruments, with a dynamical picture of an interacting market, in a simple setting. The proliferation of financial instruments apparently provides more means for risk diversification, making the market more efficient and complete. In the simple market of interacting traders discussed here, the proliferation of financial instruments erodes systemic stability and it drives the market to a critical state characterized by large susceptibility, strong fluctuations and enhanced correlations among risks. This suggests that the hypothesis of APT may not be compatible with a stable market dynamics. In this perspective, market stability acquires the properties of a common good, which suggests that appropriate measures should be introduced in derivative markets, to preserve stability. in here

Erodibility of calcareous soils as influenced by land use and intrinsic soil properties in a semiarid region of central Iran.

PubMed

Ayoubi, Shamsollah; Mokhtari, Javad; Mosaddeghi, Mohammad Reza; Zeraatpisheh, Mojtaba

2018-03-06

The most important properties affecting the soil loss and runoff were investigated, and the effects of land use on the soil properties, together with the erodibility indices in a semiarid zone, central Iran, were evaluated. The locations of 100 positions were acquired by cLHS and 0-5-cm surface soil layer samples were used for laboratory analyses from the Borujen Region, Chaharmahal-Va-Bakhtiari Province, central Iran. To measure in situ runoff and soil erodibility of three different land uses comprising dryland, irrigated farming, and rangeland, a portable rainfall simulator was used. The results showed that the high variations (coefficient of variation, CV) were obtained for electrical conductivity (EC), mean weight diameter (MWD), soil organic carbon (SOC), and soil erodibility indices including runoff volume, soil loss, and sediment concentration (CV ~ 43.6-77.4%). Soil erodibility indices showed positive and significant correlations with bulk density and negative correlations with SOC, MWD, clay content, and soil shear strength in the area under investigation. The values of runoff in the dryland, irrigated farming, and rangeland were found 1.5, 28.9, and 58.7 cm 3 ; soil loss in the dryland, irrigated farming, and rangeland were observed 0.25, 2.96, and 76.8 g; and the amount of sediment concentration in the dryland, irrigated farming, and rangeland were found 0.01, 0.11, and 0.15 g cm -3 . It is suggested that further investigations should be carried out on soil erodibility and the potential of sediment yield in various land uses with varying topography and soil properties in semiarid regions of Iran facing the high risk of soil loss.

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.

Effects of nonylphenol on juveniles and adults in the grey mullet, Liza aurata.

PubMed

Cionna, Cristina; Maradonna, Francesca; Olivotto, Ike; Pizzonia, Gianluca; Carnevali, Oliana

2006-10-01

The aim of this study was to investigate the effects of nonylphenol (NP), an environmental pollutant known to have estrogenic activity, on grey mullets. Juvenile and adult physiology was monitored by the expression of vitellogenin (VTG), which is commonly induced by estrogenic pollutants, and cytochrome P4501A1(CYP1A1) as a first signal of detoxification. The dose-response estrogenic effects of NP (25, 100, 1000 microg/l) on hepatic VTG transcript and plasma protein levels, as well as on CYP1A1 transcription and its associated ethoxyresorufin O-deethylase (EROD) activity, were assessed in juvenile Liza aurata; 17beta-estradiol (E2; 2 microg/l) treatment for 1 week served as positive control. In addition, we investigated VTG and CYP1A1 expression in adult males injected with two NP at 0.25 or 250 mg/kg body weight relative to 0.07 mg/kg of E2 as a positive control. Juvenile exposure to NP failed to induce a measurable VTG response. In the adult fish, NP exerted estrogenic effects only at the highest dose injected. E2 treatment elicited VTG induction only in adults in a time-related manner. In contrast, NP treatment induced a dose-dependent decrease in CYP1A1 response in both juveniles and adults. An inhibitory effect of E2 on CYP1A1 was evident in all treatment groups as well. These data suggest that, in biomonitoring studies, testing the expression of different biomarkers may provide a more realistic picture of the environmental conditions.

Toxicity assessment of individual ingredients of synthetic-based drilling muds (SBMs).

PubMed

Bakhtyar, Sajida; Gagnon, Marthe Monique

2012-09-01

Synthetic-based drilling muds (SBMs) offer excellent technical characteristics while providing improved environmental performance over other drilling muds. The low acute toxicity and high biodegradability of SBMs suggest their discharge at sea would cause minimal impacts on marine ecosystems, however, chronic toxicity testing has demonstrated adverse effects of SBMs on fish health. Sparse environmental monitoring data indicate effects of SBMs on bottom invertebrates. However, no environmental toxicity assessment has been performed on fish attracted to the cutting piles. SBM formulations are mostly composed of synthetic base oils, weighting agents, and drilling additives such as emulsifiers, fluid loss agents, wetting agents, and brine. The present study aimed to evaluate the impact of exposure to individual ingredients of SBMs on fish health. To do so, a suite of biomarkers [ethoxyresorufin-O-deethylase (EROD) activity, biliary metabolites, sorbitol dehydrogenase (SDH) activity, DNA damage, and heat shock protein] have been measured in pink snapper (Pagrus auratus) exposed for 21 days to individual ingredients of SBMs. The primary emulsifier (Emul S50) followed by the fluid loss agent (LSL 50) caused the strongest biochemical responses in fish. The synthetic base oil (Rheosyn) caused the least response in juvenile fish. The results suggest that the impact of Syndrill 80:20 on fish health might be reduced by replacement of the primary emulsifier Emul S50 with an alternative ingredient of less toxicity to aquatic biota. The research provides a basis for improving the environmental performance of SBMs by reducing the environmental risk of their discharge and providing environmental managers with information regarding the potential toxicity of individual ingredients.

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.

Assessing the ecological risk of soil irrigated with wastewater using in vitro cell bioassays.

PubMed

Yu, Guo; Xiao, Ruiyang; Wang, Donghong; Zhou, Jun; Wang, Zijian

2008-12-01

In the most recent research work, the accumulation of toxicants in soil was always assessed through concentration level of the target contaminants. However, assessments based on chemical analysis were limited in numbers and in their unpredictable bioavailability. An alternative assessment could be based on toxicity assessment. It means that a screening bioassay is a necessary tool for identifying and defining contaminants at the sites, which should warrant further attention. In the present study, three in vitro cell bioassays, including the SOS/umu bioassay for genotoxic effects, human estrogen receptor recombinant yeast bioassay for estrogenic effects, and ethoxyresorfin O-deethylase (EROD) with H4IIE rat hepatoma cells bioassay for Ah-receptor agonistic effects, were used for the evaluation of the accumulation of toxicants in soils irrigated with wastewater in the suburb of Beijing, China. The results indicated that there were significant increases of genotoxic, estrogenic, and Ah-receptor agonistic effects in soils irrigated with wastewater, as compared with soils irrigated with groundwater. There was the decreased effect gradient following the increase of the distances from the inlet of the wastewater. It was concluded that wastewater irrigation could cause accumulation of genotoxic, estrogenic, and Ah-receptor agonistic chemicals in soil.

Photorefractive keratectomy (PRK) at 193 nm using an erodible mask: new developments and clinical progress

NASA Astrophysics Data System (ADS)

Gordon, Michael; Seiler, Theo; Carey, Joseph P.; Friedman, Marc D.; Johnsson, N. M. F.; King, Michael C.; Muller, David F.

1993-06-01

This paper reports on our progress using an erodible mask to perform photorefractive keratectomy (PRK) for the correction of myopic astigmatism. We describe modifications to the mask, the mask eye cup and the surgical microscope aimed at simplifying the procedure and improving the ergonomics of the hardware. We report the clinical results of the post-op exam for 20 patients who have undergone PRK for myopic astigmatism under a Phase IIA study. The results compare favorably with an earlier Phase IIA study for performing PRK with a computer-controlled iris. Most important, the clinical data show the absence of any significant corneal haze and no significant decrease in spectacle corrected visual acuity. Although more long term follow-up is needed, the preliminary results support the safety and effectiveness of using an erodible mask to perform PRK for myopic astigmatism.

Synergistic and Antagonistic Mutation Responses of Human MCL-5 Cells to Mixtures of Benzo[a]pyrene and 2-Amino-1-Methyl-6-Phenylimidazo[4,5-b]pyridine: Dose-Related Variation in the Joint Effects of Common Dietary Carcinogens.

PubMed

David, Rhiannon; Ebbels, Timothy; Gooderham, Nigel

2016-01-01

Chemical carcinogens such as benzo[a]pyrene (BaP) and 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) may contribute to the etiology of human diet-associated cancer. Individually, these compounds are genotoxic, but the consequences of exposure to mixtures of these chemicals have not been systematically examined. We determined the mutagenic response to mixtures of BaP and PhIP at concentrations relevant to human exposure (micromolar to subnanomolar). Human MCL-5 cells (metabolically competent) were exposed to BaP or PhIP individually or in mixtures. Mutagenicity was assessed at the thymidine kinase (TK) locus, CYP1A activity was determined by ethoxyresorufin-O-deethylase (EROD) activity and qRT-PCR, and cell cycle was measured by flow cytometry. Mixtures of BaP and PhIP produced dose responses different from those of the individual chemicals; we observed remarkably increased mutant frequency (MF) at lower concentrations of the mixtures (not mutagenic individually), and decreased MF at higher concentrations of the mixtures, than the calculated predicted additive MF of the individual chemicals. EROD activity and CYP1A1 mRNA levels were correlated with TK MF, supporting involvement of the CYP1A family in mutation. Moreover, a cell cycle G2/M phase block was observed at high-dose combinations, consistent with DNA damage sensing and repair. Mixtures of these genotoxic chemicals produced mutation responses that differed from those expected for the additive effects of the individual chemicals. The increase in MF for certain combinations of chemicals at low concentrations that were not genotoxic for the individual chemicals, as well as the nonmonotonic dose response, may be important for understanding the mutagenic potential of food and the etiology of diet-associated cancers. David R, Ebbels T, Gooderham N. 2016. Synergistic and antagonistic mutation responses of human MCL-5 cells to mixtures of benzo[a]pyrene and 2-amino-1-methyl-6-phenylimidazo[4,5-b

Synergistic and Antagonistic Mutation Responses of Human MCL-5 Cells to Mixtures of Benzo[a]pyrene and 2-Amino-1-Methyl-6-Phenylimidazo[4,5-b]pyridine: Dose-Related Variation in the Joint Effects of Common Dietary Carcinogens

PubMed Central

David, Rhiannon; Ebbels, Timothy; Gooderham, Nigel

2015-01-01

Background Chemical carcinogens such as benzo[a]pyrene (BaP) and 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) may contribute to the etiology of human diet-associated cancer. Individually, these compounds are genotoxic, but the consequences of exposure to mixtures of these chemicals have not been systematically examined. Objectives We determined the mutagenic response to mixtures of BaP and PhIP at concentrations relevant to human exposure (micromolar to subnanomolar). Methods Human MCL-5 cells (metabolically competent) were exposed to BaP or PhIP individually or in mixtures. Mutagenicity was assessed at the thymidine kinase (TK) locus, CYP1A activity was determined by ethoxyresorufin-O-deethylase (EROD) activity and qRT-PCR, and cell cycle was measured by flow cytometry. Results Mixtures of BaP and PhIP produced dose responses different from those of the individual chemicals; we observed remarkably increased mutant frequency (MF) at lower concentrations of the mixtures (not mutagenic individually), and decreased MF at higher concentrations of the mixtures, than the calculated predicted additive MF of the individual chemicals. EROD activity and CYP1A1 mRNA levels were correlated with TK MF, supporting involvement of the CYP1A family in mutation. Moreover, a cell cycle G2/M phase block was observed at high-dose combinations, consistent with DNA damage sensing and repair. Conclusions Mixtures of these genotoxic chemicals produced mutation responses that differed from those expected for the additive effects of the individual chemicals. The increase in MF for certain combinations of chemicals at low concentrations that were not genotoxic for the individual chemicals, as well as the nonmonotonic dose response, may be important for understanding the mutagenic potential of food and the etiology of diet-associated cancers. Citation David R, Ebbels T, Gooderham N. 2016. Synergistic and antagonistic mutation responses of human MCL-5 cells to mixtures of benzo

Impact of toothpaste on abrasion of sound and eroded enamel: An in vitro white light interferometer study.

PubMed

Nakamura, Maria; Kitasako, Yuichi; Nakashima, Syozi; Sadr, Alireza; Tagami, Junji

2015-10-01

To evaluate the influence of brushing using toothpastes marketed under different categories on abrasion of sound and eroded enamel in vitro at nanometer scale using a white light interferometer (WLI). Enamel surface of resin-embedded bovine incisors were fine polished with diamond slurry and divided into testing area (approximately 2 mm x 4 mm) and reference area using a nail varnish. The enamel specimens were randomly assigned to 10 groups (n = 10 each); six of which were subjected to erosive challenge. The testing area in these eroded groups was exposed to 10 ml of Coca-Cola for 90 seconds and then rinsed for 10 seconds in deionized water (DW). Enamel specimens, except for those in one eroded group, were brushed by an automatic brushing machine with 120 linear motion strokes in 60 seconds under load of 250 g with/without toothpaste slurry. After the toothbrushing abrasion, each specimen was rinsed for 10 seconds with DW followed by immersion in artificial saliva for 2 hours. Toothpaste slurries were prepared containing one of the four toothpastes used and DW in a ratio of 1:2. The erosion-abrasion cycle was repeated three times. Then, the nail varnish was removed and enamel surface loss (SL) was measured by the WLI. Data were statistically analyzed by one-way ANOVA followed by Bonferroni's correction at significance level of 0.05. For eroded specimens, the mean SL values of groups not brushed and brushed with no toothpaste were not significantly different, but were significantly lower than those of whitening, anti-erosion and anti-caries toothpaste groups (P < 0.001). The whitening toothpaste group showed significantly higher SL than all other groups (P < 0.001). For sound enamel specimens, SL was not measured except for the whitening toothpaste group.

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.

Biomarker responses to environmental contamination in estuaries: A comparative multi-taxa approach.

PubMed

Duarte, Irina A; Reis-Santos, Patrick; França, Susana; Cabral, Henrique; Fonseca, Vanessa F

2017-08-01

Estuaries are highly productive ecosystems subjected to numerous anthropogenic pressures with consequent environmental quality degradation. In this study, multiple biomarker responses [superoxide dismutase (SOD), catalase (CAT), ethoxyresorufin O-deethylase (EROD) and glutathione S-transferase (GST) activities, as well as lipid peroxidation (LPO) and DNA damage (DNAd)] were determined in two fish (Dicentrarchus labrax and Pomatoschistus microps) and four macroinvertebrate species (Carcinus maenas, Crangon crangon, Hediste diversicolor and Scrobicularia plana) from the Ria de Aveiro and Tejo estuaries over distinct months. Two sites per estuarine system were selected based on anthropogenic pressures and magnitude of environmental contamination. Antioxidant enzyme activities in fish species suggested a ubiquitous response to oxidative stress, while biotransformation and effect biomarkers exhibited higher spatial and temporal variation. In invertebrate species, biotransformation enzyme activity was clearly less variable than in fish evidencing lower xenobiotic transformation capability. Overall, largest biomarker responses were found in the most contaminated sites (Tejo), yet species-specific patterns were evident. These should be factored in multi-taxa approaches, considering that the differential functional traits of species, such as habitat use, life-stage, feeding or physiology can influence exposure routes and biomarker responses. The Integrated Biomarker Response index highlighted patterns in biomarker responses which were not immediately evident when analyzing biomarkers individually. Overall, results provided insights into the complexity of species responses to contamination in naturally varying estuarine environments. Ultimately, multi-taxa and multi-biomarker approaches provide a comprehensive and complementary view of ecosystem health, encompassing diverse forms of biological integration and exposure routes, and allow the validation of results among markers

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. Copyright © 2014 Elsevier Ltd. All rights reserved.

Aggregate stability as an indicator of soil erodibility and soil physical quality: review and perspectives

NASA Astrophysics Data System (ADS)

Le Bissonnais, Yves; Chenu, Claire; Darboux, Frédéric; Duval, Odile; Legout, Cédric; Leguédois, Sophie; Gumiere, Silvio

2010-05-01

Aggregate breakdown due to water and rain action may cause surface crusting, slumping, a reduction of infiltration and interrill erosion. Aggregate stability determines the capacity of aggregates to resist the effects of water and rainfall. In this paper, we evaluated and reviewed the relevance of an aggregate stability measurement to characterize soil physical properties as well as to analyse the processes involved in these properties. Stability measurement assesses the sensitivity of soil aggregates to various basic disaggregation mechanisms such as slaking, differential swelling, dispersion and mechanical breakdown. It has been showed that aggregate size distributions of structural stability tests matched the size distributions of eroded aggregates under rainfall simulations and that erosion amount was well predicted using aggregate stability indexes. It means stability tests could be used to estimate both the erodibility and the size fractions that are available for crust formation and erosion processes. Several studies showed that organic matter was one of the main soil properties affecting soil stability. However, it has also been showed that aggregate stability of a given soil could vary within a year or between years. The factors controlling such changes have still to be specified. Aggregate stability appears therefore as a complex property, depending both on permanent soil characteristics and on dynamic factors such as the crusting stage, the climate and the biological activity. Despite, and may be, because of this complexity, aggregate stability seems an integrative and powerful indicator of soil physical quality. Future research efforts should look at the causes of short-term changes of structural stability, in order to fully understand all its aspects.

Predictive model for local scour downstream of hydrokinetic turbines in erodible channels

NASA Astrophysics Data System (ADS)

Musa, Mirko; Heisel, Michael; Guala, Michele

2018-02-01

A modeling framework is derived to predict the scour induced by marine hydrokinetic turbines installed on fluvial or tidal erodible bed surfaces. Following recent advances in bridge scour formulation, the phenomenological theory of turbulence is applied to describe the flow structures that dictate the equilibrium scour depth condition at the turbine base. Using scaling arguments, we link the turbine operating conditions to the flow structures and scour depth through the drag force exerted by the device on the flow. The resulting theoretical model predicts scour depth using dimensionless parameters and considers two potential scenarios depending on the proximity of the turbine rotor to the erodible bed. The model is validated at the laboratory scale with experimental data comprising the two sediment mobility regimes (clear water and live bed), different turbine configurations, hydraulic settings, bed material compositions, and migrating bedform types. The present work provides future developers of flow energy conversion technologies with a physics-based predictive formula for local scour depth beneficial to feasibility studies and anchoring system design. A potential prototype-scale deployment in a large sandy river is also considered with our model to quantify how the expected scour depth varies as a function of the flow discharge and rotor diameter.

Quantifying sediment connectivity in an actively eroding gully complex, Waipaoa catchment, New Zealand

NASA Astrophysics Data System (ADS)

Taylor, Richard J.; Massey, Chris; Fuller, Ian C.; Marden, Mike; Archibald, Garth; Ries, William

2018-04-01

Using a combination of airborne LiDAR (2005) and terrestrial laser scanning (2007, 2008, 2010, 2011), sediment delivery processes and sediment connectivity in an 20-ha gully complex, which significantly contributes to the Waipaoa sediment cascade, are quantified over a 6-year period. The acquisition of terrain data from high-resolution surveys of the whole gully-fan system provides new insights into slope processes and slope-channel linkages operating in the complex. Raw terrain data from the airborne and ground-based laser scans were converted into raster DEMs with a vertical accuracy between surveys of <±0.1 m. Grid elevations in each successive DEM were subtracted from the previous DEM to provide models of change across the gully and fan complex. In these models deposition equates to positive and erosion to negative vertical change. Debris flows, slumping, and erosion by surface runoff (gullying in the conventional sense) generated on average 95,232 m3 of sediment annually, with a standard deviation of ± 20,806 m3. The volumes of debris eroded from those areas dominated by surface erosion processes were higher than in areas dominated by landslide processes. Over the six-year study period, sediment delivery from the source zones to the fan was a factor of 1.4 times larger than the volume of debris exported from the fan into Te Weraroa Stream. The average annual volume of sediment exported to Te Weraroa Stream varies widely from 23,195 to 102,796 m3. Fluctuations in the volume of stored sediment within the fan, rather than external forcing by rainstorms or earthquakes, account for this annual variation. No large rainfall events occurred during the monitoring period; therefore, sediment volumes and transfer processes captured by this study are representative of the background conditions that operate in this geomorphic system.

Airborne laser study quantifies El Niño-induced coastal change

USGS Publications Warehouse

Sallenger, Asbury H.; Krabill, William; Brock, John H.; Swift, Robert; Jansen, Mark; Manizade, Serdar; Richmond, Bruce; Hampton, Monty; Eslinger, David

1999-01-01

Winter storms during the 1997–1998 El Niño caused extensive changes to the beaches and cliffs of the west coast of the United States, a NASA-NOAA-USGS investigation using a scanning airborne laser has found. For example, near Pacifica in central California, the cliff eroded locally as much as 10–13 m landward during the El Niño winter, at least 40 times the long term average erosion rate. However, only several hundred meters away the cliff was stable. This variability in cliff response may be related to differences in local beach changes where an accreting beach protected part of the cliff and an eroding beach exposed another part to attack by waves.

Influence of an arginine-containing toothpaste on bond strength of different adhesive systems to eroded dentin.

PubMed

Bergamin, Ana Cláudia Pietrobom; Bridi, Enrico Coser; Amaral, Flávia Lucisano Botelho; Turssi, Cecília Pedroso; Basting, Roberta Tarkany; Aguiar, Flávio Henrique Baggio; França, Fabiana Mantovani Gomes

2016-01-01

The aim of this study was to evaluate the bond strength of different adhesive systems to eroded dentin following toothbrushing with an arginine-containing toothpaste. Sixty standardized 3 × 3 × 2-mm fragments of root dentin (n = 10) were prepared. After all surfaces except the buccal surfaces were impermeabilized, specimens were subjected to an erosive wear protocol and stored for 24 hours at 37°C. The specimens underwent 1000 toothbrushing cycles with an arginine-containing toothpaste, an arginine-free toothpaste (positive control group), or artificial saliva (negative control group). Following application of a self-etching or an etch-and-rinse adhesive to the buccal surfaces of the specimens, 6-mm-high composite resin blocks were built up in 2-mm increments. After 24 hours' storage in 100% relative humidity, microtensile test specimens with an approximate area of 1 mm² were prepared. The test was performed at a speed of 0.5 mm/min until specimen fracture, and the failure patterns were evaluated using a stereoscopic loupe. Two-way analysis of variance revealed no significant difference between the toothpastes, the adhesive systems, or the interactions between toothpaste and adhesive system in terms of the bond strength to eroded dentin (P > 0.05). The predominant failure pattern was adhesive in all groups. It was concluded that a toothpaste containing arginine did not interfere with the bond between either the self-etching or the etch-and-rinse adhesive system and eroded dentin.

Influence of FGD gypsum on the properties of a highly erodible soil under conservation tillage

USDA-ARS?s Scientific Manuscript database

The performance of conservation tillage practices imposed on highly erodible soils may be improved by the use of amendments with a high solubility rate, and whose dissolution products are translocated at depth in the soil profile faster than normally used agricultural lime and fertilizer products. T...

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

Peat soil properties and erodibility: what factors affect erosion and suspended sediment yields in peat extraction areas?

NASA Astrophysics Data System (ADS)

Tuukkanen, Tapio; Marttila, Hannu; Kløve, Bjørn

2014-05-01

Peatland drainage and peat extraction operations change soil properties and expose bare peat to erosion forces, resulting in increased suspended sediment (SS) loads to downstream water bodies. SS yields from peat extraction areas are known to vary significantly between sites, but the contribution of peat properties and catchment characteristics to this variation is not well understood. In this study, we investigated peat erosion at 20 Finnish peat extraction sites by conducting in situ and laboratory measurements on peat erodibility and associated peat properties (degree of humification, peat type, bulk density, loss on ignition, porosity, moisture content, and shear strength), and by comparing the results with monitored long-term SS concentrations and loads at each catchment outlet. Here, we used a cohesive strength meter (CSM) to measure direct erosion thresholds for undisturbed soil cores collected from each study site. The results suggested that the degree of peat decomposition clearly affects peat erodibility and explains much of the variation in SS concentration between the study sites. According to CSM tests, critical shear stresses for particle entrainment were lowest (on average) in well-decomposed peat samples, while undecomposed, dry and fiber rich peat generally resisted erosion very well. Furthermore, the results indicated that two separate critical shear stresses often exist in moderately decomposed peat. In these cases, the well-decomposed parts of peat samples eroded first at relatively low shear stresses and remaining peat fibers prevented further erosion until a much higher shear stress was reached. In addition to peat soil properties, the study showed that the erosion of mineral subsoil may play a key role in runoff water SS concentration at peat extraction areas with drainage ditches extending into the mineral soil. The interactions between peat properties and peat erodibility found in this study as well as critical shear stress values obtained

Cytochrome P450-inhibitory activity of parabens and phthalates used in consumer products.

PubMed

Ozaki, Hitomi; Sugihara, Kazumi; Watanabe, Yoko; Ohta, Shigeru; Kitamura, Shigeyuki

2016-01-01

The in vitro cytochrome P450 (CYP)-inhibitory effects of 11 parabens and 7 phthalates used in consumer products, as well as their hydrolytic metabolites, were investigated, using rat liver microsomes as an enzyme source. The effects on individual CYP isozymes were evaluated by assaying inhibition of activities towards specific substrates, i.e., ethoxyresorufin O-dealkylase (EROD), methoxyresorufin O-dealkylase (MROD), pentoxyresorufin O-dealkylase (PROD), 7-benzyloxy-4-trifluoromethylcoumarin dealkylase (BFCD), 7-methoxy-4-trifluoromethylcoumarin dealkylase (MFCD) and 7-ethoxy-4-trifluoromethylcoumarin dealkylase (EFCD) activities. These activities were dose-dependently inhibited, most potently by medium-side-chain parabens (C6-9) and phthalates (C4-6), and less potently by shorter- and longer-side-chain esters. The hydrolytic product of parabens, 4-hydroxybenzoic acid, was not inhibitory, while those of phthalates, phthalic acid monoesters, showed lower inhibitory activity than the parent phthalates. Parabens showed relatively potent inhibition of MFCD activity, considered to be mainly due to CYP2C, and phthalates showed relatively potent inhibition of PROD activity, considered to be mainly due to CYP2B.

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.

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.

Lipid reserve dynamics and magnification of persistent organic pollutants in spawning sockeye salmon (Oncorhynchus nerka) from the Fraser River, British Columbia.

PubMed

Kelly, Barry C; Gray, Samantha L; Ikonomou, Michael G; Macdonald, J Steve; Bandiera, Stelvio M; Hrycay, Eugene G

2007-05-01

Pacific sockeye salmon (Oncorhynchus nerka) can travel several hundred kilometers to reach native spawning grounds and fulfill semelparous reproduction. The dramatic changes in lipid reserves during upstream migration can greatly affect internal toxicokinetics of persistent organic pollutants (POPs) such as PCBs, PCDDs, and PCDFs. We measured lipid content changes and contaminant concentrations in tissues (liver, muscle, roe/gonads) and biomarker responses (ethoxyresorufin O-deethylase or EROD activity and CYP1A levels) in two Pacific sockeye salmon stocks sampled at several locations along their spawning migration in the Fraser River, British Columbia. Muscle lipid contents declined significantly with increasing upstream migration distance and corresponded to elevated lipid normalized concentrations of PCBs and PCDD/Fs in spawning sockeye. Post-migration magnification factors (MFs) in spawning sockeye ranged between 3 and 12 and were comparable to model-predicted MFs. sigmaPCBs(150-500 ng x g(-1) lipid), sigmaPCDD/Fs (1-1000 pg x g(-1) lipid) and 2,3,7,8-TCDD toxic equivalent or TEQ levels (0.1-15 pg x g(-1) lipid) in spawning sockeye were relatively low and did not affect hepatic EROD activity/CYP1A induction. Despite a 3-fold magnification, TEQ levels in eggs of spawning Fraser River sockeye did not exceed 0.3 pg x g(-1) wet wt, a threshold level associated with 30% egg mortality in salmonids. PCBs in Fraser River sockeye are comparable to previous levels in Pacific sockeye. In contrast to Pacific sockeye from more remote coastal locations, PCDDs and PCDFs in Fraser River sockeye were generally minor components (<25%) of TEQ levels, compared to dioxin like PCB contributions (>75%). The data suggest that (i) the Fraser River is not a major contamination source of PCBs or PCDD/Fs and (ii) marine contaminant distribution, food-chain dynamics, and ocean-migration pathway are likely important factors controlling levels and patterns of POPs in returning Pacific

Biotransformation, genotoxic, and histopathological effects of environmental contaminants in European eel (Anguilla anguilla L.).

PubMed

Pacheco, Mário; Santos, Maria Ana

2002-11-01

A prolonged toxicity study was carried out in young European eel (Anguilla anguilla L.) to evaluate the effects of environmental contaminants, namely, two individual standard compounds, benzo[a]pyrene (BaP) and dehydroabietic acid (DHAA), and a complex mixture, bleached kraft pulp mill effluent (BKPME). Fish were exposed to BaP (0.22, 0.45, and 0.9 microM) and BKPME (3.12%, 6.25%, and 12.5% (v/v)) for 3, 7, and 30 days and to DHAA (0.07, 0.15, and 0.30 microM) for 3, 7, 30, 90, and 180 days. The biomarkers include biotransformation and genotoxicity indicators, such as total ethoxyresorufin O-deethylase (EROD) activity and frequency of erythrocytic nuclear abnormalities (ENAs), respectively. Hematological dynamics was assessed as frequency of immature erythrocytes (IEs). Histopathological examinations were carried out for the highest concentrations and for 30 days and longer exposures. Total EROD increases significantly only after 180 days of DHAA exposure. However, significant ENA induction was generally observed during exposure to all contaminants tested. Nevertheless, some of the ENA results suggest an altered genotoxic response, which may arise either from short-term exposures to the highest contaminant levels or long-term exposures to the lowest contaminant levels. IE frequency decreased significantly after 30 days of exposure to 0.45 microM BaP and 180 days of exposure to the entire DHAA concentration range. Increased density of pigmented macrophage aggregates in 30-day BaP- and BKPME-exposed fish as well as in 90- and 180-day DHAA-exposed fish confirmed histopathological liver alterations. Bile accumulation in hepatocytes after BaP treatment, cytoplasmic vacuolization and cell atrophy following DHAA exposure, as well as liver loss of parenchymal cells in BKPME-exposed fish, were also detected. Dispersed necrosis and focal inflammation were observed in the livers of all treated groups. Fish exposed to DHAA and BKPME showed skin and gill disruption as well as

Synchronized and sustained release of multiple components in silymarin from erodible glyceryl monostearate matrix system.

PubMed

Lu, Cheng; Lu, Yi; Chen, Jian; Zhang, Wentong; Wu, Wei

2007-05-01

Development of sustained delivery systems for herbal medicines was very difficult because of their complexity in composition. The concept of synchronized release from sustained release systems, which is characterized by release of multiple components in their original ratio that defines a herbal medicine, served as the basis for keeping the original pharmacological activity. In this study, erodible matrix systems based on glyceryl monostearate and polyethylene glycol 6000 or poloxamer 188 were prepared to perform strict control on synchronized release of the five active components of silymarin, i.e. taxifolin, silychrystin, silydianin, isosilybin and silybin. The matrix system was prepared by a melt fusion method. Synchronized release was achieved with high similarity factor f(2) values between each two of the five components. Erosion profiles of the matrix were in good correlation with release profiles of the five components, showing erosion-controlled release mechanisms. Through tuning some of the formulation variables, the system can be adjusted for synchronized and sustained release of silymarin for oral administration. In vitro hemolysis study indicated that the synchronized release samples showed a much better stabilizing effect on erythrocyte membrane.

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

NASA Astrophysics Data System (ADS)

Bravo, Rafael; Becker, Pablo; Ortiz, Pablo

2017-07-01

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.

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.

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.

Changes in physiological responses of an Antarctic fish, the emerald rock cod (Trematomus bernacchii), following exposure to polybrominated diphenyl ethers (PBDEs).

PubMed

Ghosh, Ruma; Lokman, P Mark; Lamare, Miles D; Metcalf, Victoria J; Burritt, David J; Davison, William; Hageman, Kimberly J

2013-03-15

Although polybrominated diphenyl ethers (PBDEs) have the ability to undergo long-range atmospheric transport to remote ecosystems like Antarctica, a recent study found evidence for a local source within the Antarctic. PBDEs from sewage treatment outfalls of McMurdo Station and Scott Base on Ross Island have been attributed to the high concentrations measured in emerald rock cod (Trematomus bernacchii). The potential impact of PBDEs on Antarctic fish physiology is unknown and therefore, the aim of this study was to obtain a greater understanding of physiological responses of emerald rock cod for assessing changes in ecosystem quality. A PBDE mixture (ΣPBDE 8 congeners) was administered fortnightly over 42 days and physiological changes were observed throughout this period and for a further 14 days thereafter. Changes in liver composition, molecular level changes and enzyme activities of selected detoxification-mediated and antioxidant defence markers were measured. Changes in total lipid, lipid peroxide and protein carbonyl concentrations in emerald rock cod liver were consistent with increases in nucleus surface area in the PBDE-treated groups, suggesting alterations in cellular function. Changes in the activities of selected antioxidant enzymes indirectly indicated oxidative stress, possibly resulting in the changes in liver composition. Additionally, glutathione-S-transferase (GST) activity reached its peak faster than that of ethoxyresorufin-O-deethylase (EROD), suggesting that during the early response to PBDE exposures there could be a greater involvement of GST-mediated detoxification. Thus, for at least the species examined here, protein carbonyl and lipid peroxides were useful and informative biomarkers for cellular level responses following PBDE-related exposure. Furthermore, our findings suggest that emerald rock cod exposed to PBDEs develop oxidative stress - a condition with potential consequences for fish growth, health and reproduction. Copyright �

Effects of land conversion from native shrub to pistachio orchard on soil erodibility in an arid region.

PubMed

Yakupoglu, Tugrul; Gundogan, Recep; Dindaroglu, Turgay; Kara, Zekeriya

2017-10-29

Land-use change through degrading natural vegetation for agricultural production adversely affects many of soil properties particularly organic carbon content of soils. The native shrub land and grassland of Gaziantep-Adiyaman plateau that is an important pistachio growing eco-region have been cleared to convert into pistachio orchard for the last 50 to 60 years. In this study, the effects of conversion of natural vegetation into agricultural uses on soil erodibility have been investigated. Soil samples were collected from surface of agricultural fields and adjacent natural vegetation areas, and samples were analyzed for some soil erodibility indices such as dispersion ratio (DR), erosion ratio (ER), structural stability index (SSI), Henin's instability index (I s ), and aggregate size distribution after wet sieving (AggSD). According to the statistical evaluation, these two areas were found as different from each other in terms of erosion indices except for I s index (P < 0.001 for DR and ER or P < 0.01 for SSI). In addition, native shrub land and converted land to agriculture were found different in terms of AggSD in all aggregate size groups. As a contrary to expectations, correlation tests showed that there were no any interaction between soil organic carbon and measured erodibility indices in two areas. In addition, significant relationships were determined between measured variables and soil textural fractions as statistical. These obtaining findings were attributed to changing of textural component distribution and initial aggregate size distribution results from land-use change in the study area. Study results were explained about hierarchical aggregate formation mechanism.

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.

Treatment with thiamine hydrochloride and astaxanthine for the prevention of yolk-sac mortality in Baltic salmon fry (M74 syndrome).

PubMed

Koski, P; Pakarinen, M; Nakari, T; Soivio, A; Hartikainen, K

1999-09-14

Two practical methods are reported for treating feral Baltic salmon with thiamine hydrochloride against M74 syndrome (abnormally high yolk-sac fry mortality of the Baltic salmon). Both bathing of the yolk-sac fry in thiamine hydrochloride (1000 mg l-1, 1 h) and a single intraperitoneal injection given to the female brood fish (100 mg kg-1 fish) during the summer 3 mo before stripping were shown to elevate the whole body total thiamine concentration in the fry. Both treatments were also shown to be effective in preventing mortality due to M74 syndrome. The effect of bathing the yolk-sac fry was shown to be dose-dependent. The results support the view that there is a causal relationship between the thiamine status of the yolk-sac fry and M74 mortality. An intraperitoneal injection of astaxanthine suspension administered to the female brood fish (11 mg kg-1 fish) in the summer 3 mo before stripping elevated the astaxanthine concentration in the eggs but did not affect mortality due to M74 syndrome. An interaction between astaxanthine and thiamine may occur in the developing embryo or yolk-sac fry, however. No association could be demonstrated between the various thiamine hydrochloride treatment practices and hepatic cytochrome P450 dependent 7-ethoxyresorufin-O-deethylase (EROD) activity in the yolk-sac fry. An injection of thiamine hydrochloride into the peritoneal cavity of wild Baltic salmon females could be used to raise thiamine concentrations in their offspring in the rivers. The effect on smolt production in Finnish Baltic salmon rivers needs to be investigated further, however.

Responses of shortfin eel (Anguilla australis) exposed in situ to pulp and paper effluent.

PubMed

van den Heuvel, Michael R; Landman, Michael J; Tremblay, Louis A

2006-10-01

The responses of shortfin eel (Anguilla australis) to discharges from two pulp and paper mills, municipal wastewater, and a geothermal power plant wastewater were examined. Eels were caged at 3 sites along the Tarawera River, North Island, New Zealand, to explore effects of a 3-wk exposure down a contamination gradient (Ref --> D1 --> D2). Most of the observed effects were seen in eels caged at the furthest downstream site (D2), below all the discharge areas. General hematology in eels was unaffected, as measures did not differ markedly at the two downstream sites compared with the reference site. At D2, eels were significantly lighter per unit length (reduced condition factor), although liver and spleen size (LSI and SSI) were unaffected. Significantly elevated circulating sex steroid concentrations (testosterone and estradiol) were measured in D2 eels and increasing sex steroid levels at both sites downstream of the reference site were observed. Significant ethoxyresorufin O-deethylase (EROD) activity induction was seen in D2 eels and bile chemistry showed significant accumulation of pyrene and retene equivalents. However, significantly greater concentrations of total resin acids were found in the bile of eels from the intermediate site (D1), between the two pulp and paper mills. The higher polycyclic aromatic hydrocarbon (PAH) equivalents found in the bile of D2 eels suggest that resin acid neutrals, particularly retene, are responsible for some of the effects observed in eels at the furthest downstream exposure site. Levels of pulp and paper mill extractives in sediment, including the PAH retene, support this conclusion.

The abrasive effect of commercial whitening toothpastes on eroded enamel.

PubMed

Mosquim, Victor; Martines Souza, Beatriz; Foratori Junior, Gerson Aparecido; Wang, Linda; Magalhães, Ana Carolina

2017-06-01

To evaluate the in vitro abrasive effect of commercial whitening toothpastes on eroded bovine enamel samples in respect to erosive tooth wear. 72 bovine crowns were embedded, polished and subjected to the baseline profile analysis. The samples were then protected in 2/3 of the enamel surface and were randomly assigned to six groups (n= 12/group): G1: Oral-B 3D White, G2: Close-up Diamond Attraction Power White, G3: Sorriso Xtreme White 4D, G4: Colgate Luminous White, G5: Crest (conventional toothpaste), G6:erosion only (control). All samples were submitted to an erosive pH cycling (4 x 90 seconds in 0.1% citric acid, pH 2.5, per day) and abrasive challenges (2 x 15 seconds, per day) for 7 days. After the first and the last daily cycles, the samples were subjected to abrasive challenges, using a toothbrushing machine, soft toothbrushes and slurry of the tested toothpastes (1.5 N). Between the challenges, the samples were immersed in artificial saliva. The final profile was obtained and overlaid to the baseline profile for the calculation of the erosive tooth wear (μm). The data were subjected to Kruskal-Wallis/Dunn tests (P< 0.05). G1 promoted the highest enamel wear (3.68±1.06 μm), similarly to G3 (3.17± 0.80 μm) and G4 (3.44± 1.29 μm). G3 and G4 performed similarly between them and compared with G5 (2.35± 1.44 μm). G2 (1.51± 0.95 μm) and G6 (0.85± 0.36 μm) showed the lowest enamel wear, which did not differ between them and from G5. Oral-B 3D White showed the highest abrasive potential while Close-up Diamond Attraction Power White showed the lowest abrasive potential on eroded enamel in vitro. This study showed that some commercial whitening toothpastes, especially those containing pyrophosphate associated with hydrated silica, enhanced enamel erosive wear.

Photospheric magnetic field of an eroded-by-solar-wind coronal mass ejection

NASA Astrophysics Data System (ADS)

Palacios, J.; Cid, C.; Saiz, E.; Guerrero, A.

2017-10-01

We have investigated the case of a coronal mass ejection that was eroded by the fast wind of a coronal hole in the interplanetary medium. When a solar ejection takes place close to a coronal hole, the flux rope magnetic topology of the coronal mass ejection (CME) may become misshapen at 1 AU as a result of the interaction. Detailed analysis of this event reveals erosion of the interplanetary coronal mass ejection (ICME) magnetic field. In this communication, we study the photospheric magnetic roots of the coronal hole and the coronal mass ejection area with HMI/SDO magnetograms to define their magnetic characteristics.

Tracing the source of soil organic matter eroded from temperate forest catchments using carbon and nitrogen isotopes

Treesearch

Emma P. McCorkle; Asmeret Asefaw Berhe; Carolyn T. Hunsaker; Dale W. Johnson; Karis J. McFarlane; Marilyn L. Fogel; Stephen C. Hart

2016-01-01

Soil erosion continuously redistributes soil and associated soil organic matter (SOM) on the Earth's surface, with important implications for biogeochemical cycling of essential elements and terrestrial carbon sequestration. Despite the importance of soil erosion, surprisingly few studies have evaluated the sources of eroded carbon (C). We used natural abundance...

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

Sub ablative Er: YAG laser irradiation on surface roughness of eroded dental enamel.

PubMed

Curylofo-Zotti, Fabiana Almeida; Lepri, Taísa Penazzo; Colucci, Vivian; Turssi, Cecília Pedroso; Corona, Silmara Aparecida Milori

2015-11-01

This study evaluated the effects of Er:YAG laser irradiation applied at varying pulse repetition rate on the surface roughness of eroded enamel. Bovine enamel slabs (n = 10) were embedded in polyester resin, ground, and polished. To erosive challenges, specimens were immersed two times per day in 20mL of concentrated orange juice (pH = 3.84) under agitation, during a two-day period. Specimens were randomly assigned to irradiation with the Er:YAG laser (focused mode, pulse energy of 60 mJ and energy density of 3.79 J/cm(2) ) operating at 1, 2, 3, or 4 Hz. The control group was left nonirradiated. Surface roughness measurements were recorded post erosion-like formation and further erosive episodes by a profilometer and observed through atomic force microscopy (AFM). Analysis of variance revealed that the control group showed the lowest surface roughness, while laser-irradiated substrates did not differ from each other following post erosion-like lesion formation. According to analysis of covariance, at further erosive episodes, the control group demonstrated lower surface roughness (P > 0.05), than any of the irradiated groups (P < 0.05). The pulse repetition rate of the Er:YAG laser did not affect roughness of dental enamel eroded. The AFM images showed that the specimens irradiated by the Er:YAG laser at 1 Hz presented a less rough surface than those irradiated at 2, 3, and 4 Hz. © 2015 Wiley Periodicals, Inc.

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

USDA-ARS?s Scientific Manuscript database

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...

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

Crude cacao Theobroma cacao extract reduces mutagenicity induced by benzo[a]pyrene through inhibition of CYP1A activity in vitro.

PubMed

Ohno, Marumi; Sakamoto, Kentaro Q; Ishizuka, Mayumi; Fujita, Shoichi

2009-08-01

Polyphenols have been shown to have potent antioxidant activity, and therefore, food containing polyphenols is expected to contribute to the prevention of cancer. However, food contains not only polyphenols but also various other constituents. We used the Ames test to investigate the effects of crude extracts of whole cacao products, which are known to be rich in polyphenols, on the mutagenicity of benzo[a]pyrene (B[a]P) in Salmonella typhimurium strain TA 98 and tert-butyl hydroperoxide (t-BuOOH) in S. typhimurium strain TA 102. B[a]P induces mutagenicity by metabolic activation and t-BuOOH induces it by generation of free radicals. While white chocolate did not modulate the numbers of revertant colonies produced by B[a]P treatment, milk chocolate and cacao powder extracts did. On the other hand, surprisingly, none of the cacao products tested affected the number of revertant colonies when t-BuOOH was used as the mutagen. At maximum concentration (13.25 mg cacao powder/ml), the crude cacao powder extract reduced ethoxyresorufin O-deethylase activity to 17.4% of the control, suggesting that whole cacao products inhibit cytochrome P450 (CYP) 1A activity. In conclusion, inhibition of CYP1A activity by cacao products may prevent DNA damage by reducing metabolic activation of carcinogens. Copyright 2009 John Wiley & Sons, Ltd.

Changes in cytochrome P4501A activity during development in common tern chicks fed polychlorinated biphenyls, as measured by the caffeine breath test

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

Feyk, L.A.; Giesy, J.P.; Bosveld, A.T.C.

2000-03-01

Cytochrome P4501A (CYPIA) activity is often used as a biomarker of exposure of wildlife to polyhalogenated diaromatic hydrocarbons and is usually measured ex vivo in liver tissue. A caffeine breath test (CBT) with radiolabeled substrate ({sup 14}C-caffeine) was used to measure in vivo CYP1A activity twice during development in 14 common tern (Sterna hirundo) chicks treated with polyhalogenated diaromatic hydrocarbons. Tern hatchlings were fed fish spiked with 3,3{prime}, 4,4{prime},5-pentachlorobiphenyl (PCB 126) and 2,2{prime},4,4{prime},5,5{prime}-hexachlorobiphenyl (PCB 153) such that the diet contained an average of 23, 99, or 561 pg of 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents per gram of fish for 21 d. Sixteen additionalmore » common tern chicks were similarly dosed with polyhalogenated diaromatic hydrocarbons but were not subjected to the CBT procedure. In weeks 1 and 2, caffeine N-demethylation and ethoxyresorufin-O-deethylation activity on day 21 were elevated in birds that received the greatest PCB dose. There was less constitutive and greater induction of ethoxyresorufin-O-deethylation activity than caffeine N-demethylation. The {sup 14}C-CBT was less invasive than the ethoxyresorufin-O-deethylase assay. Only one morphological parameter differed significantly between CBT subjects and no-CBT subjects fed the same level of PCBs. Bursa weight was significantly less in control CBT subjects than in control no-CBT subjects, but bursa weights did not differ among CBT and no-CBT birds from the two PCB treatment groups. No alterations of survival or growth occurred in CBT subjects compared with no-CBT subjects.« less

Ecotoxicological potential of the biocides terbutryn, octhilinone and methylisothiazolinone: Underestimated risk from biocidal pathways?

PubMed

Kresmann, Simon; Arokia, Arokia Hansel Rajan; Koch, Christoph; Sures, Bernd

2018-06-01

The use of biocides by industry, agriculture and households increased throughout the last two decades. Many new applications with known substances enriched the variety of biocidal pollution sources for the aquatic environment. While agriculture was the major source for a long time, leaching from building facades and preservation of personal care and cleaning products was identified as new sources in the last few years. With the different usage forms of biocidal products the complexity of legislative regulation increased as well. The requirements for risk assessment differ from one law to another and the potential risk of substances under different regulations might be underestimated. Still EC 50 and predicted no-effect concentration (PNEC) values gained from testing with different species are the core of environmental risk assessment, but ecotoxicological data is limited or lacking for many biocides. In this study the biocides widely used in facade coatings and household products terbutryn, octhilinone and methylisothiazolinone were tested with the Daphnia magna acute immobilisation assay, the neutral red uptake assay and the ethoxyresorufin-O-deethylase (EROD) assay, performed with rainbow trout liver (RTL-W1) cells. Further, the MTT assay with the ovarian cell line CHO-9 from Chinese hamster was used as mammalian model. Octhilinone induced the strongest effects with EC 50 values of 156μg/l in the D. magna assay, while terbutryn showed the weakest effects with 8390μg/l and methylisothiazolinone 513μg/l respectively. All other assays showed higher EC 50 values and thus only weak effects. EROD assays did not show any effects. With additional literature and database records PNEC values were calculated: terbutryn reached 0.003μg/l, octhilinone 0.05μg/l and methylisothiazolinone 0.5μg/l. Potential ecotoxicological risks of these biocides are discussed, considering environmental concentrations. Copyright © 2017 Elsevier B.V. All rights reserved.

Binding of methane to activated mineral surfaces - a methane sink on Mars?

NASA Astrophysics Data System (ADS)

Nørnberg, P.; Knak Jensen, S. J.; Skibsted, J.; Jakobsen, H. J.; ten Kate, I. L.; Gunnlaugsson, H. P.; Merrison, J. P.; Finster, K.; Bak, Ebbe; Iversen, J. J.; Kondrup, J. C.

2015-10-01

Tumbling experiments that simulate the wind erosion of quartz grains in an atmosphere of 13 C-enriched methane are reported. The eroded grains are analyzed by 13C and 29 Si solid-state NMR techniques after several months of tumbling. The analysis shows that methane has reacted with the eroded surface to form covalent Si-CH3 bonds, which stay intact for temperatures up to at least 250oC. These findings offer a model for a methane sink that might explain the fast disappearance of methane on Mars.

Developmental triclosan exposure decreases maternal, fetal, and early neonatal thyroxine: a dynamic and kinetic evaluation of a putative mode-of-action.

PubMed

Paul, Katie B; Hedge, Joan M; Bansal, Ruby; Zoeller, R Thomas; Peter, Robert; DeVito, Michael J; Crofton, Kevin M

2012-10-09

This work tests the mode-of-action (MOA) hypothesis that maternal and developmental triclosan (TCS) exposure decreases circulating thyroxine (T4) concentrations via up-regulation of hepatic catabolism and elimination of T4. Time-pregnant Long-Evans rats received TCS po (0-300mg/kg/day) from gestational day (GD) 6 through postnatal day (PND) 21. Serum and liver were collected from dams (GD20, PND22) and offspring (GD20, PND4, PND14, PND21). Serum T4, triiodothyronine (T3), and thyroid-stimulating hormone (TSH) concentrations were measured by radioimmunoassay. Ethoxy-O-deethylase (EROD), pentoxyresorufin-O-depentylase (PROD) and uridine diphosphate glucuronyltransferase (UGT) enzyme activities were measured in liver microsomes. Custom Taqman(®) qPCR arrays were employed to measure hepatic mRNA expression of select cytochrome P450s, UGTs, sulfotransferases, transporters, and thyroid hormone-responsive genes. TCS was quantified by LC/MS/MS in serum and liver. Serum T4 decreased approximately 30% in GD20 dams and fetuses, PND4 pups and PND22 dams (300mg/kg/day). Hepatic PROD activity increased 2-3 fold in PND4 pups and PND22 dams, and UGT activity was 1.5 fold higher in PND22 dams only (300mg/kg/day). Minor up-regulation of Cyp2b and Cyp3a expression in dams was consistent with hypothesized activation of the constitutive androstane and/or pregnane X receptor. T4 reductions of 30% for dams and GD20 and PND4 offspring with concomitant increases in PROD (PND4 neonates and PND22 dams) and UGT activity (PND22 dams) suggest that up-regulated hepatic catabolism may contribute to TCS-induced hypothyroxinemia during development. Serum and liver TCS concentrations demonstrated greater fetal than postnatal internal exposure, consistent with the lack of T4 changes in PND14 and PND21 offspring. These data support the MOA hypothesis that TCS exposure leads to hypothyroxinemia via increased hepatic catabolism; however, the minor effects on thyroid hormone metabolism may reflect the

Development of Surface Eroding Thermocouples in DIII-D

NASA Astrophysics Data System (ADS)

Ren, Jun; Donovan, David; Watkins, Jon; Wang, Huiqian; Rudakov, Dmitry; Murphy, Christopher; Unterberg, Ezekial; Thomas, Dan; Boivin, Rejean

2017-10-01

The Surface Eroding Thermocouple (SETC) is a specialized diagnostic for characterizing the surface temperature evolution with a high temporal resolution ( 1ms) which is especially useful in areas unobservable by line-of-sight diagnostics (e.g. IR cameras). Recently, SETCs were tested in DiMES and successfully acquired temperature signals during strike point sweeps on the lower divertor shelf. We observed that the SETCs have a sub-10 ms time response and is sufficient to resolve ELM heat pulses. Preliminary analysis shows heat fluxes measured by SETCs and IR camera agree within 20%. Comparison of SETCs, calorimeters and Langmuir probe also show good agreement. We plan to implement an array of SETCs embedded in the tiles forming the new DIII-D small angle slot (SAS) divertor. Strategies to improve the SNR of these SETCs through testing in DiMES before the final installation will be discussed. This work was supported by the US Department of Energy under DE-SC0016318 (UTK), DE-AC05-00OR22725 (ORNL), DE-FG02-07ER54917 (UCSD), DE-FC02-04ER54698 (GA), DE-AC04-94AL85000 (SNL).

Photocatalytic activity of nanostructured ZnO-ZrO2 binary oxide using fluorometric method

NASA Astrophysics Data System (ADS)

Ibrahim, M. M.

2015-06-01

Evaluation of the photocatalytic activity of ZnO-ZrO2 nanomaterials using fluorescence based technique has rarely been reported. In the present work, ZnO-ZrO2 mixed oxides coupled with various ZnO dosages (0, 10, 30, 50, 70 wt%) were prepared by impregnation method. These nanomaterials were characterized by studying their structural, surface and optical properties. The photocatalytic activity in term of quantitative determination of the active oxidative species (radOH) produced on the surface of binary oxide was evaluated using fluorescent probe method. The interaction between ZnO and ZrO2 was affected on the photocatalytic efficiency of mixture. The results show that, the addition of ZnO to ZrO2 decreased the electron-hole recombination and increased the rate of radOH radicals formation. 50 wt% ZnO-ZrO2 photocatalyst exhibited much higher photocatalytic activity. The profound effect of binary oxide catalyst was generally considered due to the high surface area, small particle size, high monoclinic phase of ZrO2 content, low band gap and the presence of surface OH groups.

Elevated Temperature Solid Particle Erosion Performance of Plasma-Sprayed Co-based Composite Coatings with Additions of Al2O3 and CeO2

NASA Astrophysics Data System (ADS)

Nithin, H. S.; Desai, Vijay; Ramesh, M. R.

2017-11-01

In this paper, investigation into solid particle erosion behavior of atmospheric plasma-sprayed composite coating of CoCrAlY reinforced with Al2O3 and CeO2 oxides on Superni 76 at elevated temperature of 600 °C is presented. Alumina particles are used as erodent at two impact angles of 30° and 90°. The microstructure, porosity, hardness, toughness and adhesion properties of the as-sprayed coatings are studied. The effects of temperature and phase transformation in the coatings during erosion process are analyzed using XRD and EDS techniques. Optical profilometer is used for accurate elucidation of erosion volume loss. CoCrAlY/CeO2 coating showed better erosion resistance with a volume loss of about 50% of what was observed in case of CoCrAlY/Al2O3/YSZ coating. Lower erosion loss is observed at 90° as compared to 30° impact angle. The erosion mechanism evaluated using SEM micrograph revealed that the coatings experienced ductile fracture exhibiting severe deformation with unusual oxide cracks. Reinforced metal oxides provide shielding effect for erodent impact, enabling better erosion resistance. The oxidation of the coating due to high-temperature exposure reforms erosion process into oxidation-modified erosion process.

Fractality of eroded coastlines of correlated landscapes.

PubMed

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

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.

The impacts of grazing land management on the wind erodibility of the Mulga Lands of western Queensland, Australia

USDA-ARS?s Scientific Manuscript database

An estimated 100 Mt of dust is eroded by wind from the Australian land surface each year. Wind erosion may be widespread across the arid and semi-arid rangelands, with impacts on soil nutrients, carbon and ecosystem services, human health, and climate. The susceptibility of landscapes to wind erosio...

Polycyclic aromatic and aliphatic hydrocarbons in Chukchi Sea biota and sediments and their toxicological response in the Arctic cod, Boreogadus saida

NASA Astrophysics Data System (ADS)

Harvey, H. Rodger; Taylor, Karen A.; Pie, Hannah V.; Mitchelmore, Carys L.

2014-04-01

As part of the Chukchi Sea Offshore Monitoring in Drilling Area-Chemical and Benthos (COMIDA CAB) project, we determined the distribution and concentrations of aliphatic n-alkanes and polycyclic aromatic hydrocarbons (PAHs) in surface sediments (0-1 cm) among 52 sites across the Chukchi Sea and in muscle tissues of the benthic Northern whelk, Neptunea heros, collected opportunistically. In addition, downcore profiles of contaminants were determined at three targeted sites to establish historic patterns. Baseline responses of PAH exposure and its potential toxicological effects were examined in the common Arctic cod, Boreogadus saida, through measures of cytochrome P4501A/ ethoxyresorufin O-deethylase (CYP1A/EROD), glutathione-S-transferase (GST), and Cu/Zn superoxide dismutase (SOD) activity in liver tissue. The total concentration of PAHs in surface sediments throughout the study area, including parent and alkyl-homologs, were very low (<1600 ng g-1 dry wt) except for a single station, where values were 2-20-fold greater than at other baseline sites (2956 ng g-1 dry wt). Alkyl-substituted PAHs were the dominant form in all surface (54-93%) and subsurface sediments (50-81% of the total), with a general decrease in total PAH concentrations observed downcore. In biota, larger Neptunea showed lower total concentrations of PAHs in foot muscles (4.5-10.7 ng g-1 wet wt) compared to smaller animals; yet aliphatic n-alkane (C19-C33) concentrations (0.655-5.20 μg g-1 wet wt) increased in larger organisms with distributions dominated by long-chain (C23-C33) hydrocarbons. In B. saida, CYP1A1, GST, and SOD enzyme levels were comparable to baseline levels previously reported in other pristine systems. Of the three assays, only SOD had a significant correlation between gene expression and enzyme activity.

Multiple biomarker responses in Prochilodus lineatus subjected to short-term in situ exposure to streams from agricultural areas in Southern Brazil.

PubMed

Vieira, Carlos Eduardo Delfino; Costa, Patrícia Gomes; Lunardelli, Bruna; de Oliveira, Luciana Fernandes; Cabrera, Liziara da Costa; Risso, Wagner Ezequiel; Primel, Ednei Gilberto; Meletti, Paulo César; Fillmann, Gilberto; Martinez, Claudia Bueno dos Reis

2016-01-15

In order to assess the quality of streams susceptible to contamination by pesticides we apply biochemical and genotoxic biomarkers in the Neotropical fish Prochilodus lineatus submitted to in situ tests. Fish were caged, for 96 h, in two streams located in areas with intensive use of pesticides, the Apertados (AP) and the Jacutinga (JC), and in a small stream (Godoy stream — GD) found inside a forest fragment adjacent to a State Park. Biochemical parameters, such as biotransformation enzymes 7-ethoxyresorufin-O-deethylase (EROD) and glutathione-S-transferase (GST), non-protein thiols (NPSH), lipoperoxidation (LPO), protein carbonylation (PCO) and acetylcholinesterase (AChE) were evaluated in various fish organs, as well as genotoxic biomarkers (damage to DNA and occurrence of micronuclei and erythrocyte nuclear abnormalities). Samples of water and sediment were collected for analysis of metals (Cu, Cr, Pb, Ni, Mn, Cd and Zn), organochloride pesticides, and triazine and glyphosate herbicides. We observed an increase in liver GST activity in fish at AP and gill GST activity in fish at JC. An increase in liver LPO was also observed in fish exposed to AP and JC. The same animals also exhibited increased DNA damage and erythrocyte nuclear abnormalities (ENAs) compared to the fish kept in GD. A number of compounds showed concentrations higher than the permitted levels, in particular, dichlorodiphenyltrichloroethane (DDT), its metabolites dichlorodiphenyldichloroethylene (DDE) and dichlorodiphenyldichloroethane (DDD), hexachlorocyclohexanes (HCH), heptachloride, diclofluanid and aldrins. These pesticides were detected at higher concentrations in water and sediment samples from AP, followed by JC and GD. The Integrated Biomarker Response Index (IBR) indicated that AP and JC (AP: 21.7 > JC: 18.5 > GD: 12.6) have the worst environmental quality. Integrated biomarker analysis revealed that the alterations observed related well with the levels of environmental contaminants

Exposure to sublethal levels of PCB-126 impacts fuel metabolism and swimming performance in rainbow trout.

PubMed

Bellehumeur, Karyne; Lapointe, Dominique; Cooke, Steven J; Moon, Thomas W

2016-09-01

Polychlorinated biphenyls (PCBs) are recognized physiological stressors to fish which over time may impair individual performance and perhaps fitness by inducing changes that could have population-level consequences. PCB-126 (3,3',4,4',5-pentachlorobiphenyl) accumulates in lipids and can subsequently be released into the bloodstream during periods of high activity that involve the mobilization of stored fuels to meet with increasing energy demands. The goal of this study was to determine if a sublethal exposure to PCB-126 altered the content of tissue energy supplies (carbohydrates, proteins, amino acids, triglycerides) and impaired swimming performance as well as oxygen consumption in rainbow trout (Oncorhynchus mykiss). Trout were injected intraperitoneally with a single Low (100μgkg(-1)) or High (400μgkg(-1)) dose of PCB-126 then swimming performance and metabolic rates from 1 to 9days post-injection were compared to Control (non-dosed) fish. Liver ethoxyresorufin-O-deethylase (EROD) activity was assessed as an indication of PCB-126 intoxication while plasma and white muscle tissue metabolites were analyzed as an index of physiological disturbance. Swimming performance, assessed using two successive modified critical swimming speed (Ucrit) tests, was highest for fish in the High PCB-126 treatment; however, their initial condition factor (K) was also higher, largely due to their greater body mass. Trout in the High and Low PCB-126 treatments exhibited impaired recovery following intense exercise as they swam comparatively poorly when provided a second challenge. PCB-exposed fish exhibited reduced spleen somatic indices as well as muscle glucose and glycogen contents; whereas plasma cortisol and glucose levels were elevated, indicating higher metabolic costs during recovery and muscle restoration. Overall, this research provides insights into the sublethal effects of a toxic organic compound on swimming performance in trout. Copyright © 2016 Elsevier Inc. All

Tumor prevalence and biomarkers of exposure in brown bullhead (Ameiurus nebulosus) from Back River, Furnace Creek, and Tuckahoe River, Maryland.

PubMed

Pinkney, A E; Harshbarger, J C; May, E B; Melancon, M J

2004-05-01

Brown bullheads (Ameiurus nebulosus) were collected from 2 locations near Baltimore, Maryland, Back River and Furnace Creek, and 1 (reference) location, Tuckahoe River, to compare the prevalence of tumors (liver and skin) and visible skin lesions (fin erosion and abnormal barbels). Cytochrome P450 activity measured as ethoxyresorufin-O-deethylase, biliary PAH-like fluorescent metabolites, and fillet contaminant concentrations were determined as indicators of exposure in a randomly selected subset of the fish. There were no significant differences in liver tumor prevalence: Back River = 8% (4/50), Furnace Creek = 0% (0/50), and Tuckahoe River = 2.6% (1/39; p = 0.20, extension of Fisher's exact test). Skin tumor prevalence was as follows: Furnace Creek = 12% (6/50), Back River = 8% (4/50), and Tuckahoe River = 0% (0/39; p = 0.063). In the Back River fish, there was a 40% (20/50) prevalence of fin erosion and a 28% (14/50) prevalence of abnormal (shortened, clubbed, or missing) barbels. Fin erosion was not observed in the other collections, and only 10% (5/50) of the Furnace Creek fish had abnormal barbels (p < 0.001 for both lesions). There were statistically significant differences in mean EROD activity, with levels in Furnace Creek and Back River fish approximately twice that found in Tuckahoe River fish. There were also significant differences in mean benzo(a)pyrene-like bile metabolite concentrations: the lowest mean was in the Tuckahoe River fish, 8 times higher in Furnace Creek fish, and 13 times higher in Back River fish. Of the 3 groups, the Back River bullheads appear to be most adversely affected by contaminant exposure because they had the highest prevalence of liver tumors, fin erosion, and abnormal barbels.

Tumor prevalence and biomarkers of exposure in brown bullhead (Ameiurus nebulosus) from Back River, Furnace Creek, and Tuckahoe River, Maryland

USGS Publications Warehouse

Pinkney, A.E.; Harshbarger, J.C.; May, E.B.; Melancon, M.J.

2004-01-01

Brown bullheads (Ameiurus nebulosus) were collected from 2 locations near Baltimore, Maryland, Back River and Furnace Creek, and 1 (reference) location, Tuckahoe River, to compare the prevalence of tumors (liver and skin) and visible skin lesions (fin erosion and abnormal barbels). Cytochrome P450 activity measured as ethoxyresorufin-O-deethylase, biliary PAH-like fluorescent metabolites, and fillet contaminant concentrations were determined as indicators of exposure in a randomly selected subset of the fish. There were no significant differences in liver tumor prevalence: Back River = 8% (4/50), Furnace Creek = 0% (0/50), and Tuckahoe River = 2.6% (1/39; p = 0.20, extension of Fishers exact test). Skin tumor prevalence was as follows: Furnace Creek = 12% (6/50), Back River = 8% (4/50), and Tuckahoe River = 0% (0/39; p = 0.063). In the Back River fish, there was a 40% (20/50) prevalence of fin erosion and a 28% (14/50) prevalence of abnormal (shortened, clubbed, or missing) barbels. Fin erosion was not observed in the other collections, and only 10% (5/50) of the Furnace Creek fish had abnormal barbels (p < 0.001 for both lesions). There were statistically significant differences in mean EROD activity, with levels in Furnace Creek and Back River fish approximately twice that found in Tuckahoe River fish. There were also significant differences in mean benzo(a)pyrene-like bile metabolite concentrations: the lowest mean was in the Tuckahoe River fish, 8 times higher in Furnace Creek fish, and 13 times higher in Back River fish. Of the 3 groups, the Back River bullheads appear to be most adversely affected by contaminant exposure because they had the highest prevalence of liver tumors, fin erosion, and abnormal barbels.

Glyphosate and AMPA distribution in wind-eroded sediment derived from loess soil.

PubMed

Bento, Célia P M; Goossens, Dirk; Rezaei, Mahrooz; Riksen, Michel; Mol, Hans G J; Ritsema, Coen J; Geissen, Violette

2017-01-01

Glyphosate is one of the most used herbicides in agricultural lands worldwide. Wind-eroded sediment and dust, as an environmental transport pathway of glyphosate and of its main metabolite aminomethylphosphonic acid (AMPA), can result in environmental- and human exposure far beyond the agricultural areas where it has been applied. Therefore, special attention is required to the airborne transport of glyphosate and AMPA. In this study, we investigated the behavior of glyphosate and AMPA in wind-eroded sediment by measuring their content in different size fractions (median diameters between 715 and 8 μm) of a loess soil, during a period of 28 days after glyphosate application. Granulometrical extraction was done using a wind tunnel and a Soil Fine Particle Extractor. Extractions were conducted on days 0, 3, 7, 14, 21 and 28 after glyphosate application. Results indicated that glyphosate and AMPA contents were significantly higher in the finest particle fractions (median diameters between 8 and 18 μm), and lowered significantly with the increase in particle size. However, their content remained constant when aggregates were present in the sample. Glyphosate and AMPA contents correlated positively with clay, organic matter, and silt content. The dissipation of glyphosate over time was very low, which was most probably due to the low soil moisture content of the sediment. Consequently, the formation of AMPA was also very low. The low dissipation of glyphosate in our study indicates that the risk of glyphosate transport in dry sediment to off-target areas by wind can be very high. The highest glyphosate and AMPA contents were found in the smallest soil fractions (PM 10 and less), which are easily inhaled and, therefore, contribute to human exposure. Copyright © 2016 Elsevier Ltd. All rights reserved.

Prenatal administration of the cytochrome P4501A inducer, {Beta}-naphthoflavone (BNF), attenuates hyperoxic lung injury in newborn mice: Implications for bronchopulmonary dysplasia (BPD) in premature infants

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

Couroucli, Xanthi I., E-mail: xanthic@bcm.edu; Liang Yanhong Wei; Jiang Weiwu

Supplemental oxygen contributes to the development of bronchopulmonary dysplasia (BPD) in premature infants. In this investigation, we tested the hypothesis that prenatal treatment of pregnant mice (C57BL/6J) with the cytochrome P450 (CYP)1A1 inducer, ss-napthoflavone (BNF), will lead to attenuation of lung injury in newborns (delivered from these dams) exposed to hyperoxia by mechanisms entailing transplacental induction of hepatic and pulmonary CYP1A enzymes. Pregnant mice were administered the vehicle corn oil (CO) or BNF (40 mg/kg), i.p., once daily for 3 days on gestational days (17-19), and newborns delivered from the mothers were either maintained in room air or exposed tomore » hyperoxia (> 95% O{sub 2}) for 1-5 days. After 3-5 days of hyperoxia, the lungs of CO-treated mice showed neutrophil infiltration, pulmonary edema, and perivascular inflammation. On the other hand, BNF-pretreated neonatal mice showed decreased susceptibility to hyperoxic lung injury. These mice displayed marked induction of ethoxyresorufin O-deethylase (EROD) (CYP1A1) and methoxyresorufin O-demethylase (MROD) (CYP1A2) activities, and levels of the corresponding apoproteins and mRNA levels until PND 3 in liver, while CYP1A1 expression alone was augmented in the lung. Prenatal BNF did not significantly alter gene expression of pulmonary NAD(P)H quinone reductase (NQO1). Hyperoxia for 24-72 h resulted in increased pulmonary levels of the F{sub 2}-isoprostane 8-iso-PGF{sub 2{alpha}}, whose levels were decreased in mice prenatally exposed to BNF. In conclusion, our results suggest that prenatal BNF protects newborns against hyperoxic lung injury, presumably by detoxification of lipid hydroperoxides by CYP1A enzymes, a phenomenon that has implications for prevention of BPD in infants. - Highlights: > Supplemental oxygen is routinely administered to premature infants. > Hyperoxia causes lung injury in experimental animals. > Prenatal treatment of mice with beta-naphthoflavone attenuates

Bond Stability of a Universal Adhesive System to Eroded/Abraded Dentin After Deproteinization.

PubMed

Augusto, M G; Torres, Crg; Pucci, C R; Schlueter, N; Borges, A B

Erosive/abrasive challenges can potentially compromise bonding to dentin. Aiming to improve the quality and stability of bonding to this substrate, this study investigated the combined effect of erosion and toothbrush abrasion on the microtensile bond strength (μTBS) stability to dentin using a universal adhesive system in total and self-etching modes, associated or not associated with deproteinization. Bovine dentin specimens were divided into five groups according to the organic matrix condition (n=20): control (C); erosion (E); erosion + abrasion (EA); erosion + sodium hypochlorite (EH); erosion + abrasion + sodium hypochlorite (EAH). The groups were further divided (n=10) according to the mode of application (total or self-etching) of a universal adhesive. After the bonding procedure, composite blocks were built up, and the samples were cut to obtain sticks for μTBS testing. For each specimen, one-half of the sticks was immediately tested, and the other one-half was tested after artificial aging (5000 thermocycles, 5°C and 55°C). Three-way analysis of variance (α=5%) showed a significant difference for the triple interaction ( p=0.0007). Higher μTBS means were obtained for the EH and EAH groups compared with the E and EA groups. The control group showed immediate μTBS values similar to that of the E and EA groups for both bond strategies. Erosion and erosion/abrasion did not significantly influence the immediate μTBS to dentin. Artificial aging reduced μTBS values for the groups C, E, and EA using the total-etching mode. Deproteinization maintained the bond stability to artificially aged eroded and eroded/abraded dentin.

An in situ investigation into the abrasion of eroded dental hard tissues by a whitening dentifrice.

PubMed

Turssi, C P; Faraoni, J J; Rodrigues, A L; Serra, M C

2004-01-01

This crossover study aimed to investigate abrasion of previously eroded hard dental tissues by a whitening dentifrice compared to a regular dentifrice. After a 3-day lead-in period, 14 volunteers were randomly assigned to use one of the toothpastes while wearing a removable appliance, containing 3 enamel and 3 root dentine slabs on each side. On the first day salivary pellicle was allowed to form. Twice daily for the following 3 days, one side of each appliance was immersed in an acidic carbonated drink ex vivo while the other side remained unexposed. Specimens were then brushed with the allocated dentifrice. After a 3-day washout period, new sets of enamel and dentine slabs were mounted in the appliances and the participants commenced period 2 using the alternative toothpaste. Acid-treated specimens always showed more wear than untreated specimens. The whitening dentifrice did not significantly increase the wear of softened enamel compared with the regular dentifrice. Brushing with the whitening toothpaste led to significantly greater wear of sound enamel and of both eroded and sound dentine than the regular dentifrice. The results suggest that whitening dentifrices may not increase the wear of acid-softened enamel but may have a more deleterious effect on dentine than regular toothpastes.

Field sampling of loose erodible material: A new method to consider the full particle-size range

NASA Astrophysics Data System (ADS)

Klose, Martina; Gill, Thomas E.

2017-04-01

The aerodynamic entrainment of sand and dust is determined by the atmospheric forces exerted onto the soil surface and by the soil-surface condition. If aerodynamic forces are strong enough to generate sand and dust lifting, the entrained sediment amount still critically depends on the supply of loose particles readily available for lifting. This loose erodible material (LEM) is sometimes defined as the thin layer of loose particles on top of a crusted surface. Here, we more generally define LEM as loose particles or particle aggregates available for entrainment, which may or may not overlay a soil crust. Field sampling of LEM is difficult and only few attempts have been made. Motivated by saltation as the most efficient process to generate dust emission, methods have focused on capturing LEM in the sand-size range or on determining the potential of a soil surface to be eroded by aerodynamic forces and particle impacts. Here, our focus is to capture the full particle-size distribution of LEM in situ, including the dust and sand-size range, to investigate the potential and likelihood of dust emission mechanisms (aerodynamic entrainment, saltation bombardment, aggregate disintegration) to occur. A new vacuum method is introduced and its capability to sample LEM without significant alteration of the LEM particle-size distribution is investigated.

Soil Organic Matter recovery on eroding alluvial surfaces on Iceland

NASA Astrophysics Data System (ADS)

Kuhn, N. J.; Würsch, M.; Hunziker, M.; Şórsson, J.

2012-04-01

Soil Erosion has been assessed to have no significant effect on greenhouse gas releases due to the balance between decomposition, burial, and uptake from the atmosphere through photosynthesis by vegetation and subsequent litter decomposition. The validity of the "zero-emission" balance of soil erosion is limited to sites where vegetation growth is not limited by soil degradation. In this study, the recovery of soil organic matter on sites subject to severe erosion and subsequent soil reclamation by the introduction of Lupinus nootkatensis is studied. Preliminary results indicate that the recovery is extremely slow (scale of decades). In particular, an incipient soil development, including the availability of freely available nitrogen, appear to limit the establishment of a closed vegetation cover. These results therefore indicate that in situations where land degradation leads to a complete destruction of the fertile soil layer, the assumption of dynamic replacement of eroded soil Carbon stocks cannot be applied.

In-situ activation of CuO/ZnO/Al.sub.2 O.sub.3 catalysts in the liquid phase

DOEpatents

Brown, Dennis M.; Hsiung, Thomas H.; Rao, Pradip; Roberts, George W.

1989-01-01

The present invention relates to a method of activation of a CuO/ZnO/Al.sub.2 O.sub.3 catalyst slurried in a chemically inert liquid. Successful activation of the catalyst requires the use of a process in which the temperature of the system at any time is not allowed to exceed a certain critical value, which is a function of the specific hydrogen uptake of the catalyst at that same time. This process is especially critical for activating highly concentrated catalyst slurries, typically 25 to 50 wt %. Activation of slurries of CuO/ZnO/Al.sub.2 O.sub.3 catalyst is useful in carrying out the liquid phase methanol or the liquid phase shift reactions.

Assessment of biological effects of chlorinated hydrocarbons in osprey chicks

USGS Publications Warehouse

Elliott, J.E.; Wilson, L.K.; Henny, Charles J.; Trudeau, Suzanne F.; Leighton, Frederick A.; Kennedy, Sean W.; Cheng, Kimberly M.

2001-01-01

Osprey (Pandion haliaetus) eggs were collected during 1995 and 1996 at seven sites along the Fraser and Columbia River systems of British Columbia, Canada, and Washington and Oregon, USA. Fifty-four eggs were placed into a laboratory incubator. Thirty-eight of the hatched chicks were sacrificed within 24 h. Hatching success did not differ among sites and therefore between treatment and reference areas. Residual yolk sacs of eggs collected downstream of the large bleached-kraft pulp mill at Castlegar contained greater mean concentrations of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD, 2,930 ng/kg lipid) compared with reference sites such as the Nechako River, an upper tributary of the Fraser system (33.7 ng/kg). Total polychlorinated biphenyls (PCBs) in yolk sacs were also higher at Castlegar and in samples from the Columbia River downstream of Portland, Oregon, compared with those from the Nechako River. Concentrations of measured chemicals, including TCDD toxic equivalents (TEQs), total PCBs, p,pa??-dichlorodiphenylethylene (p,pa??-DDE), and other organochlorines were not different in eggs that failed to hatch compared with calculated whole-egg values for hatched eggs. There were significant biochemical responses; a hepatic cytochrome P4501A (CYP1A) cross-reactive protein was detected in all samples tested and correlated positively with ethoxyresorufin o-deethylase (EROD) activity and yolk sac concentrations of TEQs and total PCBs. Tissue concentrations of vitamin A compounds varied among sites and correlated positively with yolk sac concentrations of TEQs and PCBs. Morphological, histological, and other physiological parameters, including chick growth, edema, deformities, and hepatic and renal porphyrin concentrations, neither varied among sites nor showed concentration-related effects.

Genotoxic effects of old landfill leachate on HepG2 cells after nitration/ultrafiltration/reverse osmosis membrane treatment process.

PubMed

Cheng, Rong; Zhao, Ling; Yin, Pinghe

2017-12-01

Toxicity assessment of nitration/ultrafiltration/reverse osmosis (nitration/UF/RO) project, which has recently been widely used as an efficient process with applications in practical leachate treatment, was very limited. In the present study, DNA damage of leachates was investigated before and after the nitration/UF/RO process by a battery of assays with human hepatoma cells. Methyletrazolium assay showed a high cytotoxicity of 97.1% after being exposed to the highest concentration of raw leachate for 24 h, and a cytotoxicity of 26% in effluent at a concentration of 30% (v/v). Both comet assay (24 h) and γH2AX flow cytometer assay (3 h) showed increased levels of DNA damage in cells exposed to raw leachate and after nitration/UF-treated leachate followed by a significant increase of 7-ethoxyresorufin-O-deethylase activity. However, the effluent after nitration/UF/RO treatment showed no significant difference compared to negative control for γH2AX flow cytometer assay but slight DNA damage at concentrations of 20% and 30% (v/v) as well as increase of 7-ethoxyresorufin-O-deethylase. Analysis showed that nitration/UF/RO process exhibited high removal of physicochemical indexes and significant reduction of toxic and genotoxic effects of leachate, but still demands an improvement to reduce all possible negative risks to the environment and humans. Copyright © 2017 John Wiley & Sons, Ltd. Copyright © 2017 John Wiley & Sons, Ltd.

Hepatic microsomal monooxygenase activity in black-crowned night herons (BCNHS) from the Chesapeake basin

USGS Publications Warehouse

Melancon, M.J.; Rattner, B.A.; Rice, C.P.; Hines, R.K.; Eisemann, J.

1992-01-01

In a continuation of our studies on the use of hepatic cytochromes P450 as a biomarker for contaminant exposure, BCNH eggs were collected from Baltimore Harbor (BH) (n = 20), Washington National Zoo (WNZ) (n = 13) and Chincoteague National Wildlife Refuge (CNWR) (reference location) (n = 20). Eggs were artificially incubated and sacrificed at pipping. Livers were snap frozen in liquid nitrogen and stored at -80?C until assay. Hepatic microsomes were prepared by differential centrifugation of homogenates and assayed for protein, benzyloxy-resorufin-O-dealkylase, (BROD) ethoxyresorufinO-dealkylase (EROD) and pentoxyresorufin-O-dealkylase (PROD). Monooxygenase assays were run in triplicate using a computer-coupled fluorometric microwell plate scanner. Values for EROD and BROD, but not PROD, from BH and WNZ were significantly greater (approximately double) than those from CNWR. Organochlorine pesticide residues were much higher in carcasses from BH and WNZ as compared to CNWR. Carcasses are presently being analyzed for PCB congeners.

PCBs, liver lesions, and biomarker responses in adult walleye (Stizostedium vitreum vitreum) collected from Green Bay, Wisconsin

USGS Publications Warehouse

Barron, Mace G.; Anderson, Michael J.; Cacela, Dave; Lipton, Joshua; Teh, Swee J.; Hinton, David E.; Zelikoff, Judith T.; Dikkeboom, Audrey L.; Tillitt, Donald E.; Holey, Mark; Denslow, Nancy

2000-01-01

Adult walleye were collected from several locations in the Lower Fox River and Green Bay, Wisconsin (the assessment area) and two relatively uncontaminated reference locations (Lake Winnebago and Patten Lake, Wisconsin) between July and October in 1996 and 1997. Whole body and liver samples collected in 1996 were analyzed for total PCBs, PCB congeners, and liver histological lesions. Follow-up sampling in 1997 included examination of liver histopathology, PCBs in liver samples, measurement of ethoxyresorufin-O-deethylase (EROD) activity, immunological evaluation of kidney and blood samples, measurement of plasma vitellogenin, and examination of tissues for parasites as well as bacterial and viral infections. Mean PCB concentrations in whole body and liver samples were elevated in assessment area walleye (4.6 to 8.6 and 3.6 to 6.4 mg/kg wet weight, respectively) compared to PCB concentrations in reference areas (0.04 mg/kg in walleye fillets from Lake Winnebago). A significant (p < 0.01) elevation was observed in the prevalence (26%) of hepatic preneoplastic foci of cellular alteration (FCA) and neoplasms in 5 to 8 year old walleye collected from the assessment area, compared to reference area fish (6% prevalence). Walleye from the assessment area also contained multiple FCA and hepatic tumors per liver sample, whereas no tumors and a reduced prevalence of FCA were observed in reference area walleye. Both tumors and FCA were more prevalent in female fish than in male fish within the 5 to 8 year age classes. There were no remarkable effects on immunological parameters in assessment area walleye, although hematocrit was elevated and blood monocyte counts were 40% lower than those of reference area fish. The data did not show any clear distinctions in the prevalence of disease between reference and assessment area walleye. EROD activity was similar in assessment area and reference area walleye. Plasma vitellogenin was elevated in female walleye from eastern Green Bay

In situ investigation of the effect of TiF4 and CO2 laser irradiation on the permeability of eroded enamel.

PubMed

Lepri, Taísa Penazzo; Colucci, Vivian; Turssi, Cecília Pedroso; Corona, Silmara Aparecida Milori

2015-06-01

Interest in erosion and its role in tooth wear has increased considerably. Due to the limited contribution of patients in modifying their dietary habits, therapeutic resources aiming to reduce the progression of erosion-like lesions have been discussed. This study sought to evaluate the effect of TiF4 and CO2 laser in controlling the permeability of in situ eroded enamel. Ten volunteers wore an intraoral palatal device containing two enamel slabs, treated with TiF4 gel and TiF4 gel + CO2 or placebo gel and placebo gel + CO2. After the washout period, volunteers were crossed over to the other treatment. During both phases, specimens were submitted to erosive challenges and then evaluated for permeability measured as the percentage of copper ion penetration over the total enamel thickness. Two-way analysis of variance (ANOVA) revealed that there was a significant interaction between the factors under study (p = 0.0002). Tukey's test showed that TiF4 significantly reduced the enamel permeability of eroded enamel specimens, regardless of whether CO2 laser irradiation was performed. It may be concluded that when the placebo gel was applied, CO2 laser was able to reduce enamel permeability; however, when TiF4 was applied, laser irradiation did not imply a reduction in permeability. TiF4 provided a lower permeability of eroded enamel, regardless of whether the CO2 laser was used. Copyright © 2015 Elsevier Ltd. All rights reserved.

Estimating the Amount of Eroded Section in a Partially Exhumed Basin from Geophysical Well Logs: An Example from the North Slope

USGS Publications Warehouse

Burns, W. Matthew; Hayba, Daniel O.; Rowan, Elisabeth L.; Houseknecht, David W.

2007-01-01

The reconstruction of burial and thermal histories of partially exhumed basins requires an estimation of the amount of erosion that has occurred since the time of maximum burial. We have developed a method for estimating eroded thickness by using porosity-depth trends derived from borehole sonic logs of wells in the Colville Basin of northern Alaska. Porosity-depth functions defined from sonic-porosity logs in wells drilled in minimally eroded parts of the basin provide a baseline for comparison with the porosity-depth trends observed in other wells across the basin. Calculated porosities, based on porosity-depth functions, were fitted to the observed data in each well by varying the amount of section assumed to have been eroded from the top of the sedimentary column. The result is an estimate of denudation at the wellsite since the time of maximum sediment accumulation. Alternative methods of estimating exhumation include fission-track analysis and projection of trendlines through vitrinite-reflectance profiles. In the Colville Basin, the methodology described here provides results generally similar to those from fission-track analysis and vitrinite-reflectance profiles, but with greatly improved spatial resolution relative to the published fission-track data and with improved reliability relative to the vitrinite-reflectance data. In addition, the exhumation estimates derived from sonic-porosity logs are independent of the thermal evolution of the basin, allowing these estimates to be used as independent variables in thermal-history modeling.

Manure and tillage use in remediation of eroded land and impacts on soil chemical properties.

PubMed

Mikha, Maysoon M; Benjamin, Joseph G; Vigil, Merle F; Poss, David J

2017-01-01

Soil loss through wind and water erosion is an ongoing problem in semiarid regions. A thin layer of top soil loss over a hectare of cropland could be corresponding to tons of productive soil loss per hectare. The objectives of this study were to evaluate the influence of beef feedlot manure, tillage and legume grass mixtures on changes in soil quality and nutrient components. The study was initiated in 2006 on an eroded site near Akron, Colorado, on a Norka-Colby very-fine sandy loam (fine-silty, mixed, mesic, Aridic, Argiustolls). Tillage treatments were no-tillage, shallow tillage (sweeps operations with V-blade) and deep tillage (DT; moldboard plow operations). In one set of plots, DT was implemented biannually (DT-2); and in another set the DT was done once at the initiation of the experiment in 2006. Amendments consisted of beef manure and urea (46-0-0), N fertilizer. Both amendments were added at low and high rates. A control treatment, with no fertilizer or manure added, was included with no-tillage and shallow tillage only. Six years of manure addition and tillage significantly altered soil chemical properties compared with fertilizer and grass legume mixtures. Across all the tillage treatments, at the 0-30 cm depth, soil pH from 2006 to 2012, was reduced 1.8 fold with high-manure compared with high-fertilizer treatment. Soil EC, Na, and SAR increased by 2.7 fold while soil P increase by 3.5 fold with high-manure treatment compared with low-manure from 2006 to 2012 across all the tillage treatments at the surface 0-30 cm. Soil organic carbon associated with high-manure was 71% higher than low-manure and 230% higher than high-fertilizer treatments in the 0-60 cm depth. Similar patterns were observed with soil total N. Overall, manure amendments greatly improved the soil nutrient status on this eroded site. However, the legume grass mixtures showed little effect on improving soils chemical properties. The micronutrients supplied by manure improved the soil

Manure and tillage use in remediation of eroded land and impacts on soil chemical properties

PubMed Central

Mikha, Maysoon M.; Benjamin, Joseph G.; Vigil, Merle F.; Poss, David J.

2017-01-01

Soil loss through wind and water erosion is an ongoing problem in semiarid regions. A thin layer of top soil loss over a hectare of cropland could be corresponding to tons of productive soil loss per hectare. The objectives of this study were to evaluate the influence of beef feedlot manure, tillage and legume grass mixtures on changes in soil quality and nutrient components. The study was initiated in 2006 on an eroded site near Akron, Colorado, on a Norka-Colby very-fine sandy loam (fine-silty, mixed, mesic, Aridic, Argiustolls). Tillage treatments were no-tillage, shallow tillage (sweeps operations with V-blade) and deep tillage (DT; moldboard plow operations). In one set of plots, DT was implemented biannually (DT-2); and in another set the DT was done once at the initiation of the experiment in 2006. Amendments consisted of beef manure and urea (46-0-0), N fertilizer. Both amendments were added at low and high rates. A control treatment, with no fertilizer or manure added, was included with no-tillage and shallow tillage only. Six years of manure addition and tillage significantly altered soil chemical properties compared with fertilizer and grass legume mixtures. Across all the tillage treatments, at the 0–30 cm depth, soil pH from 2006 to 2012, was reduced 1.8 fold with high-manure compared with high-fertilizer treatment. Soil EC, Na, and SAR increased by 2.7 fold while soil P increase by 3.5 fold with high-manure treatment compared with low-manure from 2006 to 2012 across all the tillage treatments at the surface 0–30 cm. Soil organic carbon associated with high-manure was 71% higher than low-manure and 230% higher than high-fertilizer treatments in the 0–60 cm depth. Similar patterns were observed with soil total N. Overall, manure amendments greatly improved the soil nutrient status on this eroded site. However, the legume grass mixtures showed little effect on improving soils chemical properties. The micronutrients supplied by manure improved the

Constructing MnO{sub 2}/single crystalline ZnO nanorod hybrids with enhanced photocatalytic and antibacterial activity

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

Yu, Weiwei; Liu, Tiangui, E-mail: tianguiliu@gmail.com; Cao, Shiyi

In order to improve the photocatalytic and antibacterial activity of ZnO nanorods, ZnO nanorods decorated with MnO{sub 2} nanoparticles (MnO{sub 2}/ZnO nanorod hybrids) were prepared by using microwave assisted coprecipitation method under the influence of hydrogen peroxide, and the structure, photocatalytic activity and antibacterial property of the products were studied. Experimental results indicated that MnO{sub 2} nanoparticles are decorated on the surface of single crystalline ZnO nanorods. Moreover, the resultant MnO{sub 2}/ZnO nanorod hybrids have been proven to possess good photocatalytic and antibacterial activity, which their degradated efficiency for Rhodamin B (RhB) is twice as the pure ZnO nanorods. Enhancementmore » for photocatalytic and antibacterial activity is mainly attributed to the low band gap energy and excellent electrochemical properties of MnO{sub 2} nanoparticles. - Graphical abstract: The MnO{sub 2}/single crystalline ZnO nanorods hybrids, which MnO{sub 2} nanoparticles are loaded on the surface of ZnO nanorods, were prepared by the step-by-step precipitation method under the assistance of ammonia and hydrogen peroxide. Display Omitted - Highlights: • MnO{sub 2}/ZnO nanorod hybrids were prepared by the step-by-step assembly method. • Single crystalline ZnO nanorods can be decorated by MnO{sub 2} nanoparticles. • MnO{sub 2}/ZnO nanorod hybrids possess good photocatalytic and antibacterial activity. • MnO{sub 2} can improve the photocatalytic activity of ZnO nanorods under visible light.« less

Water activities of NaClO4, Ca(ClO4)2, and Mg(ClO4)2 brines from experimental heat capacities: Water activity >0.6 below 200 K

NASA Astrophysics Data System (ADS)

Toner, J. D.; Catling, D. C.

2016-05-01

Perchlorate salts found on Mars are extremely hygroscopic and form low eutectic temperature aqueous solutions, which could allow liquid water to exist on Mars despite cold and dry conditions. The formation, dynamics, and potential habitability of perchlorate salt solutions can be broadly understood in terms of water activity. Water activity controls condensation and evaporation of water vapor in brines, deliquescence and efflorescence of crystalline salts, and ice formation during freezing. Furthermore, water activity is a basic parameter defining the habitability of aqueous solutions. Despite the importance of water activity, its value in perchlorate solutions has only been measured at 298.15 K and at the freezing point of water. To address this lack of data, we have determined water activities in NaClO4, Ca(ClO4)2, and Mg(ClO4)2 solutions using experimental heat capacities measured by Differential Scanning Calorimetry. Our results include concentrations up to near-saturation and temperatures ranging from 298.15 to 178 K. We find that water activities in NaClO4 solutions increase with decreasing temperature, by as much as 0.25 aw from 298.15 to 178 K. Consequently, aw reaches ∼0.6-0.7 even for concentrations up to 15 molal NaClO4 below 200 K. In contrast, water activities in Ca(ClO4)2 and Mg(ClO4)2 solutions generally decrease with decreasing temperature. The temperature dependence of water activity indicates that low-temperature NaClO4 solutions will evaporate and deliquesce at higher relative humidity, crystallize ice at higher temperature, and potentially be more habitable for life (at least in terms of water activity) compared to solutions at 298.15 K. The opposite effects occur in Ca(ClO4)2 and Mg(ClO4)2 solutions.

Preparation and solar-light photocatalytic activity of TiO2 composites: TiO2/kaolin, TiO2/diatomite, and TiO2/zeolite

NASA Astrophysics Data System (ADS)

Li, Y.; Li, S. G.; Wang, J.; Li, Y.; Ma, C. H.; Zhang, L.

2014-12-01

Three TiO2 loaded composites, TiO2/kaolin, TiO2/diatomite, and TiO2/zeolite, were prepared in order to improve the solar-light photocatalytic activity of TiO2. The results showed that the photocatalytic activity could obviously be enhanced by loading appropriate amount of inorganic mineral materials. Meanwhile, TiO2 content, heat-treatment temperature and heat-treatment time on the photocatalytic activity were reviewed. Otherwise, the effect of solar light irradiation time and dye concentration on the photocatalytic degradation of Acid Red B was investigated. Furthermore, the degradation mechanism and adsorption process were also discussed.

Beluga whale liver microsomal cytochrome P4501A (CYP1A) enzymes

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

Bullock, P.L.; Addison, R.; Lockhart, L.

1995-12-31

Beluga whale (Delphinapterus leucas) liver from the Canadian arctic was analyzed for the presence of CYP1A enzymes, as part of current studies on biomarkers for environmental contamination. CYP1A1-associated 7-ethoxyresorufin O-dealkylase activity (EROD) varied 13 fold among sixteen male whale liver microsomal samples and 31 fold among five females. Similarly, the rate of 7-methoxyresorufin O-dealkylation (MROD) varied 7 fold and 3 fold in microsomal samples from males and females, respectively. Furthermore, 7-pentoxyresorufin O-dealkylase activity (PROD) varied 10 fold in both sexes. None of these enzyme activities were sexually differentiated, and EROD and MROD were inhibited by {alpha}-naphthoflavone. There was very goodmore » correlation between EROD and MROD (r{sup 2} = .894), EROD and PROD (r{sup 2} = .909), but MROD and PROD were not as well correlated (r{sup 2} = 785). On Western immunoblots, a single band was recognized in Beluga whale liver microsomes by a polygonal antibody raised against an oligopeptide related to trout CYP1A1. This antibody also recognized purified rat CYP1A1 (56 kDa) and stained only one band (56 kDa) in liver microsomes isolated from male rats treated with {beta}-naphthoflavone. The interindividual variation in EROD paralleled differences in the amount of whale liver microsomal protein that cross-reacted with the anti-peptide antibody. The results suggest that Beluga whale liver contains at least one CYP1A enzyme which catalyzes the 0-dealkylation of 7-ethoxy, 7-methoxy and 7-pentoxyresorufin and has a molecular weight less than that of rat CYP1A1, but similar to rat CYP1A2 (52 kDa).« less

Origin of Active Oxygen in a Ternary CuO x /Co 3O 4–CeO 2 Catalyst for CO Oxidation

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

Liu, Zhigang; Wu, Zili; Peng, Xihong

2014-11-14

In this paper, we have studied CO oxidation over a ternary CuO x/Co 3O 4-CeO 2 catalyst and employed the techniques of N 2 adsorption/desporption, XRD, TPR, TEM, in situ DRIFTS and QMS (Quadrupole mass spectrometer) to explore the origin of active oxygen. DRIFTS-QMS results with labeled 18O2 indicate that the origin of active oxygens in CuO x/Co 3O 4-CeO 2 obeys a model, called as queue mechanism. Namely gas-phase molecular oxygens are dissociated to atomic oxygens and then incorporate in oxygen vacancies located at the interface of Co 3O 4-CeO 2 to form active crystalline oxygens, and these activemore » oxygens diffuse to the CO-Cu + sites thanks to the oxygen vacancy concentration magnitude and react with the activated CO to form CO 2. This process, obeying a queue rule, provides active oxygens to form CO 2 from gas-phase O 2 via oxygen vacancies and crystalline oxygen at the interface of Co 3O 4-CeO 2.« less

Photocatalytic properties and selective antimicrobial activity of TiO2(Eu)/CuO nanocomposite

NASA Astrophysics Data System (ADS)

Michal, Robert; Dworniczek, Ewa; Caplovicova, Maria; Monfort, Olivier; Lianos, Panagiotis; Caplovic, Lubomir; Plesch, Gustav

2016-05-01

TiO2(Eu)/CuO nanocomposites were prepared by precipitation method. The anatase nanocrystallites with a size of 26 nm exhibited well crystallized and characteristical dipyramidal morphology and {1 0 1} and {0 0 1} faceting. Transmission electron microscopy photographs with atomic resolution showed that the Eu(III) dopants were bounded on surface of titania. In the composites, the CuO nanocrystals exhibiting a monoclinic tenorite structure with a size in the range from 2 to 5 nm were grafted to the surface of titania. The influence of copper(II) oxide led to distinct selectivity in the photocatalytic and antimicrobial properties of the investigated TiO2(Eu)/CuO nanocomposites. While the presence of CuO nanocrystals strongly increased the photocatalytic production of hydrogen by ethanol reforming, it decreased the activity in photoinduced total mineralization of phenol comparing with non-modified TiO2(Eu). In investigated TiO2(Eu)/CuO powders, the photoinduced antimicrobial activity against membranes of Enterococcus species was influenced by the selective binding of CuO to the surface of the microorganism leading to distinct selectivity in their action. The activity against Enterococcus faecalis was higher than against Enterococcus faecium.

Sensitivity Analysis of the USLE Soil Erodibility Factor to Its Determining Parameters

NASA Astrophysics Data System (ADS)

Mitova, Milena; Rousseva, Svetla

2014-05-01

Soil erosion is recognized as one of the most serious soil threats worldwide. Soil erosion prediction is the first step in soil conservation planning. The Universal Soil Loss Equation (USLE) is one of the most widely used models for soil erosion predictions. One of the five USLE predictors is the soil erodibility factor (K-factor), which evaluates the impact of soil characteristics on soil erosion rates. Soil erodibility nomograph defines K-factor depending on soil characteristics, such as: particle size distribution (fractions finer that 0.002 mm and from 0.1 to 0.002 mm), organic matter content, soil structure and soil profile water permeability. Identifying the soil characteristics, which mostly influence the K-factor would give an opportunity to control the soil loss through erosion by controlling the parameters, which reduce the K-factor value. The aim of the report is to present the results of analysis of the relative weight of these soil characteristics in the K-factor values. The relative impact of the soil characteristics on K-factor was studied through a series of statistical analyses of data from the geographic database for soil erosion risk assessments in Bulgaria. Degree of correlation between K-factor values and the parameters that determine it was studied by correlation analysis. The sensitivity of the K-factor was determined by studying the variance of each parameter within the range between minimum and maximum possible values considering average value of the other factors. Normalizing transformation of data sets was applied because of the different dimensions and the orders of variation of the values of the various parameters. The results show that the content of particles finer than 0.002 mm has the most significant relative impact on the soil erodibility, followed by the content of particles with size from 0.1 mm to 0.002 mm, the class of the water permeability of the soil profile, the content of organic matter and the aggregation class. The

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.

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

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

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

Izaurralde, R Cesar C.; Malhi, S. S.; Nyborg, M.

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.more » 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.« less

O 2 Activation by Non-Heme Iron Enzymes

DOE PAGES

Solomon, Edward I.; Goudarzi, Serra; Sutherlin, Kyle D.

2016-10-28

The non-heme Fe enzymes are ubiquitous in nature and perform a wide range of functions involving O 2 activation. These had been difficult to study relative to heme enzymes; however, spectroscopic methods have now been developed that provide significant insight into the correlation of structure with function. This Current Topics article summarizes both the molecular mechanism these enzymes use to control O 2 activation in the presence of cosubstrates and the oxygen intermediates these reactions generate. Three types of O 2 activation are observed. First, non-heme reactivity is shown to be different from heme chemistry where a low-spin Fe III-OOHmore » non-heme intermediate directly reacts with substrate. Also, two subclasses of non-heme Fe enzymes generate high-spin Fe IV=O intermediates that provide both σ and π frontier molecular orbitals that can control selectivity. Lastly, for several subclasses of non-heme Fe enzymes, substrate binding to the Fe II site leads to the one electron reductive activation of O 2 to an Fe III-superoxide capable of H-atom abstraction and electrophilic attack.« less

O 2 Activation by Non-Heme Iron Enzymes

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

Solomon, Edward I.; Goudarzi, Serra; Sutherlin, Kyle D.

The non-heme Fe enzymes are ubiquitous in nature and perform a wide range of functions involving O 2 activation. These had been difficult to study relative to heme enzymes; however, spectroscopic methods have now been developed that provide significant insight into the correlation of structure with function. This Current Topics article summarizes both the molecular mechanism these enzymes use to control O 2 activation in the presence of cosubstrates and the oxygen intermediates these reactions generate. Three types of O 2 activation are observed. First, non-heme reactivity is shown to be different from heme chemistry where a low-spin Fe III-OOHmore » non-heme intermediate directly reacts with substrate. Also, two subclasses of non-heme Fe enzymes generate high-spin Fe IV=O intermediates that provide both σ and π frontier molecular orbitals that can control selectivity. Lastly, for several subclasses of non-heme Fe enzymes, substrate binding to the Fe II site leads to the one electron reductive activation of O 2 to an Fe III-superoxide capable of H-atom abstraction and electrophilic attack.« less

Runoff and erosion from a rapidly eroding pinyon-juniper hillslope

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

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

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 ofmore » 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.« less

Initial Response of Pine Seedlings and Weeds to Dried Sewage Sludge in Rehabilitation of an Eroded Forest Site

Treesearch

Charles R. Berry

1977-01-01

Dried sewage sludge was applied at rates of 0, 17, 34, and 69 metric tons/ha on a badly eroded forest site in the Piedmont region of northeast Georgia. Production of weed bio mass varied directly with amount of sludge applied. Heigh growth for both shortleafand loblolly pine seedlings appeared to be greater on plots receiving 17 metric tons of sludge/ha, bu differences...

Synthesis, optical properties and efficient photocatalytic activity of CdO/ZnO hybrid nanocomposite

NASA Astrophysics Data System (ADS)

Reddy, Ch Venkata; Babu, B.; Shim, Jaesool

2018-01-01

Pure CdO, ZnO and CdO/ZnO hybrid nanocomposite photocatalyst were synthesized using simple co-precipitation technique and studied in detail. The synthesized photocatalysts were characterized using several measurements such as X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), surface analysis (BET), diffuse reflectance UV-vis spectroscopy, X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, FT-IR, TG-DTA and photoluminescence (PL). The XRD results revealed that the hexagonal and cubic crystal structure of CdO and ZnO nanoparticles. The optical response for the composite showed the presence of separate absorption signature for CdO and ZnO in the visible region at about 510 nm and 360 nm respectively. The CdO/ZnO hybrid nanocomposite photocatalyst exhibited enhanced photocatalytic degradation activity compared to pristine CdO and ZnO. The enhanced photocatalytic activity may be due to the higher specific surface area and significantly reduced the electron-hole recombination rate.

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

Fabrication of SnO2-TiO2 core-shell nanopillar-array films for enhanced photocatalytic activity

NASA Astrophysics Data System (ADS)

Cheng, Hsyi-En; Lin, Chun-Yuan; Hsu, Ching-Ming

2017-02-01

Immobilized or deposited thin film TiO2 photocatalysts are suffering from a low photocatalytic activity due to either a low photon absorption efficiency or a high carrier recombination rate. Here we demonstrate that the photocatalytic activity of TiO2 can be effectively improved by the SnO2-TiO2 core-shell nanopillar-array structure which combines the benefits of SnO2/TiO2 heterojunction and high reaction surface area. The SnO2-TiO2 core-shell nanopillar-array films were fabricated using atomic layer deposition and dry etching techniques via barrier-free porous anodic alumina templates. The photocatalytic activity of the prepared films was evaluated by methylene blue (MB) bleaching under 352 nm UV light irradiation. The results show that the photocatalytic activity of TiO2 film was 45% improved by introducing a SnO2 film between TiO2 and ITO glass substrate and was 300% improved by using the SnO2-TiO2 core-shell nanopillar-array structure. The 45% improvement by the SnO2 interlayer is attributed to the SnO2/TiO2 heterojunction which separates the photogenerated electron-hole pairs in TiO2 for MB degradation, and the high photocatalytic activity of the SnO2-TiO2 core-shell nanopillar-array films is attributed to the three dimensional SnO2/TiO2 heterojunction which owns both the carrier separation ability and the high photocatalytic reaction surface area.

Preparation, characterization and photocatalytic activities of TiO2-SrTiO3 composites

NASA Astrophysics Data System (ADS)

Wang, Yan; Zhu, Lianjie; Gao, Fubo; Xie, Hanjie

2017-01-01

Series of TiO2-SrTiO3 composites were synthesized by hydrothermal method, using TiO2 nanotube array as a precursor and Sr(OH)2 as a Sr source material. TiO2-SrTiO3 products with various composition were obtained by simply changing the reaction time. The as-synthesized products were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The optical properties were studied by means of UV-Vis absorption spectroscopy and photoluminescence (PL) spectra. Their photocatalytic activities were assessed by photodegradation of rhodamine B (RhB) solution and the photocatalytic reaction mechanism was discussed. The TiO2-SrTiO3 composites obtained at 2 h exhibits the highest activity for photodegradation of RhB.

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.

Computational multicore on two-layer 1D shallow water equations for erodible dambreak

NASA Astrophysics Data System (ADS)

Simanjuntak, C. A.; Bagustara, B. A. R. H.; Gunawan, P. H.

2018-03-01

The simulation of erodible dambreak using two-layer shallow water equations and SCHR scheme are elaborated in this paper. The results show that the two-layer SWE model in a good agreement with the data experiment which is performed by Louvain-la-Neuve Université Catholique de Louvain. Moreover, the parallel algorithm with multicore architecture are given in the results. The results show that Computer I with processor Intel(R) Core(TM) i5-2500 CPU Quad-Core has the best performance to accelerate the computational time. Moreover, Computer III with processor AMD A6-5200 APU Quad-Core is observed has higher speedup and efficiency. The speedup and efficiency of Computer III with number of grids 3200 are 3.716050530 times and 92.9% respectively.

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

Thermostable photocatalytically active TiO2 anatase nanoparticles

NASA Astrophysics Data System (ADS)

Qi, Fei; Moiseev, Anna; Deubener, Joachim; Weber, Alfred

2011-03-01

Anatase is the low-temperature (300-550 °C) crystalline polymorph of TiO2 and it transforms to rutile upon heating. For applications utilizing the photocatalytic properties of nanoscale anatase at elevated temperatures (over 600 °C) the issue of phase stabilisation is of major interest. In this study, binary TiO2/SiO2 particles were synthesized by a flame aerosol process with TiCl4 and SiCl4 as precursors. The theoretical Si/Ti ratio was varied in the range of 0.7-1.3 mol/mol. The synthesized TiO2/SiO2 samples were heat treated at 900 and 1,000 °C for 3 h to determine the thermostability of anatase. Pyrogenic TiO2 P25 (from Evonik/Degussa, Germany) widely applied as photocatalyst was used as non-thermostabilized reference material for comparison of photocatalytic activity of powders. Both the non-calcinated and calcinated powders were characterized by means of XRD, TEM and BET. Photocatalytic activity was examined with dichloroacetic acid (DCA) chosen as a model compound. It was found that SiO2 stabilized the material retarding the collapse of catalyst surface area during calcination. The weighted anatase content of 85% remains completely unchanged even after calcination at 1,000 °C. The presence of SiO2 layer/bridge as spacer between TiO2 particles freezes the grain growth: the average crystallite size increased negligibly from 17 to 18 nm even during the calcination at 1,000 °C. Due to the stabilizing effect of SiO2 the titania nanoparticles calcinated at 900 and 1,000 °C show significant photocatalytic activity. Furthermore, the increase in photocatalytic activity with calcination temperature indicates that the titania surface becomes more accessible either due to intensified cracking of the SiO2 layer or due to enhanced transport of SiO2 into the necks thus releasing additional titania surface.

Antimicrobial activity of 9-O-acyl- and 9-O-benzoyl-substituted berberrubines.

PubMed

Hong, S W; Kim, S H; Jeun, J A; Lee, S J; Kim, S U; Kim, J H

2000-05-01

In the course of a structure-activity relationship study on berberrubine derivatives, a series of compounds bearing 9-O-acyl-(4-6) and 9-O-benzoyl- (7) substituents was synthesized with the expectation of increasing the antimicrobial activity. One of the berberrubine derivatives, 9-lauroylberberrubine chloride was the most active against Gram-positive bacteria Enterococcus faecalis, Staphylococcus aureus, Staphylococcus epidermidis, Micrococcus luteus, Bacillus subtilis as well as the Gram-negative bacterium Klebsiella pneumoniae in comparison to berberine, the currently used antibiotic in clinic. This result suggested that the presence of lipophilic substituents of certain structures and sizes might be crucial for the optimal antimicrobial activity.

Theoretical Investigation of Methane Hydroxylation over Isoelectronic [FeO]2+- and [MnO]+-Exchanged Zeolites Activated by N2O.

PubMed

Mahyuddin, M Haris; Shiota, Yoshihito; Staykov, Aleksandar; Yoshizawa, Kazunari

2017-09-05

While the most likely structure of the active site in iron-containing zeolites has been recently identified as [FeO] 2+ (Snyder et al. Nature 2016, 536, 317-321), the mechanism for the direct conversion of methane to methanol over this active species is still debatable between the direct-radical-rebound or nonradical (concerted) mechanism. Using density functional theory on periodic systems, we calculated the two reaction mechanisms over two d 4 isoelectronic systems, [FeO] 2+ and [MnO] + zeolites. We found that [FeO] 2+ zeolites favor the direct-radical-rebound mechanism with low CH 4 activation energies, while [MnO] + zeolites prefer the nonradical mechanism with higher CH 4 activation energies. These contrasts, despite their isoelectronic structures, are mainly due to the differences in the metal coordination number and O α (oxo) spin density. Moreover, molecular orbital analyses suggest that the zeolite steric hindrance further degrades the reactivity of [MnO] + zeolites toward methane. Two types of zeolite frameworks, i.e., medium-pore ZSM-5 (MFI framework) and small-pore SSZ-39 (AEI framework) zeolites, were evaluated, but no significant differences in the reactivity were found. The rate-determining reaction step is found to be methanol desorption instead of methane activation. Careful examination of the most stable sites hosting the active species and calculation for N 2 O decomposition over [Fe] 2+ -MFI and -AEI zeolites were also performed.

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

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.

A ternary Cu2O-Cu-CuO nanocomposite: a catalyst with intriguing activity.

PubMed

Sasmal, Anup Kumar; Dutta, Soumen; Pal, Tarasankar

2016-02-21

In this work, the syntheses of Cu2O as well as Cu(0) nanoparticle catalysts are presented. Copper acetate monohydrate produced two distinctly different catalyst particles with varying concentrations of hydrazine hydrate at room temperature without using any surfactant or support. Then both of them were employed separately for 4-nitrophenol reduction in aqueous solution in the presence of sodium borohydride at room temperature. To our surprise, it was noticed that the catalytic activity of Cu2O was much higher than that of the metal Cu(0) nanoparticles. We have confirmed the reason for the exceptionally high catalytic activity of cuprous oxide nanoparticles over other noble metal nanoparticles for 4-nitrophenol reduction. A plausible mechanism has been reported. The unusual activity of Cu2O nanoparticles in the reduction reaction has been observed because of the in situ generated ternary nanocomposite, Cu2O-Cu-CuO, which rapidly relays electrons and acts as a better catalyst. In this ternary composite, highly active in situ generated Cu(0) is proved to be responsible for the hydride transfer reaction. The mechanism of 4-nitrophenol reduction has been established from supporting TEM studies. To further support our proposition, we have prepared a compositionally similar Cu2O-Cu-CuO nanocomposite using Cu2O and sodium borohydride which however displayed lower rate of reduction than that of the in situ produced ternary nanocomposite. The evolution of isolated Cu(0) nanoparticles for 4-nitrophenol reduction from Cu2O under surfactant-free condition has also been taken into consideration. The synthetic procedures of cuprous oxide as well as its catalytic activity in the reduction of 4-nitrophenol are very convenient, fast, cost-effective, and easily operable in aqueous medium and were followed spectrophotometrically. Additionally, the Cu2O-catalyzed 4-nitrophenol reduction methodology was extended further to the reduction of electronically diverse nitroarenes. This

The catalytic role of tungsten electrode material in the plasmachemical activity of a pulsed corona discharge in water

NASA Astrophysics Data System (ADS)

Lukes, Petr; Clupek, Martin; Babicky, Vaclav; Sisrova, Irena; Janda, Vaclav

2011-06-01

The effects of tungsten material used as a high-voltage needle electrode on the production of hydrogen peroxide and the degradation of dimethylsulfoxide (DMSO) caused by a pulsed corona discharge in water were investigated. A reactor of needle-plate electrode geometry was used. The erosion of the tungsten electrodes by the discharge was evaluated. The yields of H2O2 production and the decomposition of DMSO by the discharge, which were obtained using the tungsten electrodes, were compared with those determined for titanium electrodes. The electrode erosion increased significantly with an increase in the solution conductivity. A large fraction (50-70%) of the eroded tungsten electrode material was released into the solution in dissolved form as tungstate WO_4^{2-} ions. A correlation between the amount of eroded tungsten material released into the solution and the chemical effects induced by the discharge was determined. Lower yields of H2O2 and a higher degradation of DMSO by the discharge were obtained using the tungsten electrodes than were determined using titanium electrodes. Tungstate ions were shown to play a dominant role in the decomposition of H2O2, which was produced by the discharge using a tungsten electrode. The higher degradation of DMSO that was determined for tungsten was attributed to the tungstate-catalyzed oxidation of DMSO by H2O2, in addition to the oxidation of DMSO by OH radicals. Such a mechanism was supported by the detection of degradation by-products of DMSO (methanesulfonate, sulfate and dimethyl sulfone). The catalytic role of tungstate ions in the plasmachemical activity of the discharge generated using a tungsten electrode was also demonstrated on a pH-dependent decomposition of H2O2 and DMSO.

The thermodynamic activity of ZnO in silicate melts

NASA Astrophysics Data System (ADS)

Reyes, R. A.; Gaskell, D. R.

1983-12-01

The activity of ZnO in ZnO-SiO2 and CaO-ZnO-SiO2 melts has been measured at 1560 °C using a transpiration technique with CO-CO2 mixtures as the carrier gas. The activities of ZnO in dilute solution in 42 wt pct SiO2-38 wt pct CaO-20 wt pct A12O3 in the range 1400° to 1550 °C and in 62 wt pct SiO2-23.3 wt pct CaO-14.7 wt pct A12O3 at 1550 °C have also been measured. The measured free energies of formation of ZnO-SiO2 melts are significantly more negative than published estimated values and this, together with the behavior observed in the system CaO-Al2O3-SiO2, indicate that ZnO is a relatively basic oxide. The results are discussed in terms of the polymerization model of binary silicate melts and ideal silicate mixing in ternary silicate melts. The behavior of ZnO in dilute solution in CaO-Al2O3-SiO2 melts is discussed in terms of the possibility of the fluxing of ZnO by iron blast furnace slags.

Effect of sulfation on the surface activity of CaO for N2O decomposition

NASA Astrophysics Data System (ADS)

Wu, Lingnan; Hu, Xiaoying; Qin, Wu; Dong, Changqing; Yang, Yongping

2015-12-01

Limestone addition to circulating fluidized bed boilers for sulfur removal affects nitrous oxide (N2O) emission at the same time, but mechanism of how sulfation process influences the surface activity of CaO for N2O decomposition remains unclear. In this paper, we investigated the effect of sulfation on the surface properties and catalytic activity of CaO for N2O decomposition using density functional theory calculations. Sulfation of CaO (1 0 0) surface by the adsorption of a single gaseous SO2 or SO3 molecule forms stable local CaSO3 or CaSO4 on the CaO (1 0 0) surface with strong hybridization between the S atom of SOx and the surface O anion. The formed local CaSO3 increases the barrier energy of N2O decomposition from 0.989 eV (on the CaO (1 0 0) surface) to 1.340 eV, and further sulfation into local CaSO4 remarkably increases the barrier energy to 2.967 eV. Sulfation from CaSO3 into CaSO4 is therefore the crucial step for deactivating the surface activity for N2O decomposition. Completely sulfated CaSO4 (0 0 1) and (0 1 0) surfaces further validate the negligible catalytic ability of CaSO4 for N2O decomposition.

Mechanisms of butylated hydroxytoluene chemoprevention of aflatoxicosis-inhibition of aflatoxin B{sub 1} metabolism

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

Guarisco, John A.; Hall, Jeffery O.; Coulombe, Roger A.

Chemoprevention of toxicoses and/or cancer through the use of nutrients or pharmacologic compounds is the subject of intense study. Among the many compounds examined, food additives such as antioxidants are being considered due to their ability to reduce disease formation by either induction or inhibition of key enzyme systems. One such compound, butylated hydroxytoluene (BHT), has been found to protect against cancer formation caused by exposure to aflatoxin B{sub 1} (AFB{sub 1}) in rodents. We have shown that dietary BHT protects against clinical signs of aflatoxicosis in turkeys, a species that is very susceptible to this mycotoxin. In this study,more » the effect of BHT on AFB{sub 1} metabolism and other cytochrome P450 (CYP)-related enzyme activities in turkey liver microsomes was examined to discern possible mechanisms of BHT-mediated protection against aflatoxicosis. Ethoxyresorufin O-deethylase (EROD), methoxyresorufin O-demethylase (MROD), prototype activities for CYP1A1 and 1A2, respectively, were decreased in the BHT fed (4000 ppm) animals, while oxidation of nifedipine, a prototype activity for CYP3A4, was increased. However, BHT added to microsomal incubations inhibited these CYP activities in a concentration-related manner. Importantly, BHT inhibited conversion of AFB{sub 1} to the reactive intermediate AFB{sub 1}-8,-9-epoxide (AFBO), exhibiting Michaelis-Menton competitive inhibition kinetics (Ki = 0.81 {mu}M). Likewise, microsomes prepared from turkeys fed BHT were significantly less active in AFBO formation compared to those from control birds. When turkeys were fed BHT for up to 40 days, residual BHT was present in liver, breast meat, thigh meat and abdominal fat in concentrations substantially below U.S. FDA guidelines for this antioxidant, but in concentrations greater than the Ki, likely sufficient to inhibit bioactivation of AFB{sub 1}in vivo. BHT-induced hydropic degeneration in the livers of BHT fed animals was significantly greater in

Microbial oxidation of lithospheric organic carbon in rapidly eroding tropical mountain soils

NASA Astrophysics Data System (ADS)

Hemingway, Jordon D.; Hilton, Robert G.; Hovius, Niels; Eglinton, Timothy I.; Haghipour, Negar; Wacker, Lukas; Chen, Meng-Chiang; Galy, Valier V.

2018-04-01

Lithospheric organic carbon (“petrogenic”; OCpetro) is oxidized during exhumation and subsequent erosion of mountain ranges. This process is a considerable source of carbon dioxide (CO2) to the atmosphere over geologic time scales, but the mechanisms that govern oxidation rates in mountain landscapes are poorly constrained. We demonstrate that, on average, 67 ± 11% of the OCpetro initially present in bedrock exhumed from the tropical, rapidly eroding Central Range of Taiwan is oxidized in soils, leading to CO2 emissions of 6.1 to 18.6 metric tons of carbon per square kilometer per year. The molecular and isotopic evolution of bulk OC and lipid biomarkers during soil formation reveals that OCpetro remineralization is microbially mediated. Rapid oxidation in mountain soils drives CO2 emission fluxes that increase with erosion rate, thereby counteracting CO2 drawdown by silicate weathering and biospheric OC burial.

Experimental Study of Acid Treatment Toward Characterization of Structural, Optical, and Morphological Properties of TiO2-SnO2 Composite Thin Film

NASA Astrophysics Data System (ADS)

Fajar, M. N.; Hidayat, R.; Triwikantoro; Endarko

2018-04-01

The TiO2-SnO2 thin film with single and double-layer structure has successfully synthesized on FTO (Fluorine-doped Tin Oxide) substrate using the screen printing technique. The structural, optical, and morphological properties of the film were investigated by XRD, UV-Vis, and SEM, respectively. The results showed that the single and double-layer structure of TiO2-SnO2 thin film has mixed phase with a strong formation of casseritte phase. The acid treatment effect on TiO2-SnO2 thin film decreases the peak intensity of anatase phase formation and thin film’s absorbance values. The morphological study is also revealed that the single layer TiO2-SnO2 thin film had a more porous nature and decreased particle size distribution after acid treatment, while the double-layer TiO2-SnO2 thin film Eroded due to acid treatment.

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.

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

Antibacterial activities of magnesium oxide (MgO) nanoparticles against foodborne pathogens

NASA Astrophysics Data System (ADS)

Jin, Tony; He, Yiping

2011-12-01

The antibacterial activities of magnesium oxide nanoparticles (MgO NP) alone or in combination with other antimicrobials (nisin and ZnO NP) against Escherichia coli O157:H7 and Salmonella Stanley were investigated. The results show that MgO NP have strong bactericidal activity against the pathogens, achieving more than 7 log reductions in bacterial counts. The antibacterial activity of MgO NP increased as the concentrations of MgO increased. A synergistic effect of MgO in combination with nisin was observed as well. However, the addition of ZnO NP to MgO NP did not enhance the antibacterial activity of MgO against both pathogens. Scanning electron microscopy was used to characterize the morphological changes of E. coli O157:H7 before and after antimicrobial treatments. It was revealed that MgO NP treatments distort and damage the cell membrane, resulting in a leakage of intracellular contents and eventually the death of bacterial cells. These results suggest that MgO NP alone or in combination with nisin could potentially be used as an effective antibacterial agent to enhance food safety.

Biomarker analyses in caged and wild fish suggest exposure to pollutants in an urban area with a landfill.

PubMed

Hanson, Niklas; Larsson, Åke

2011-06-01

An unexpectedly high frequency of skeletal deformations in brown trout has previously been observed in the brook Vallkärrabäcken in southern Sweden. Environmental pollutants from storm water and leachate from an old landfill have been suggested as responsible for the observed deformations. Biomarkers in farmed rainbow trout, placed in tanks with water supplied from the brook, were used to investigate if exposure to pollutants may induce toxic responses in fish. Furthermore, biomarkers were also measured in wild brown trout that were caught in the brook. The most important finding was that the hepatic ethoxyresorufin-O-deethylase (EROD) activity was five to seven times higher for rainbow trout and brown trout in exposed areas compared to reference sites (P<0.001). Analyses of bile in rainbow trout showed that the concentration of PAH-metabolites was two to three times higher (P<0.001) in the exposed areas. However, due to their smaller size and the feeding status, only insufficient amounts of bile could be retrieved from the wild brown trout. The study provides evidence for pollution in parts of Vallkärrabäcken. It is therefore possible that the previously observed high frequency of skeletal damage have been caused by pollutants. The methodology with farmed rainbow trout in flow through tanks worked well and provided more information about the occurrence of pollutants in Vallkärrabäcken than the data from brown trout. The main reasons for this were that the size and the feeding status of the fish could be controlled. This allowed a total of 21 biomarkers to be analyzed in farmed rainbow trout compared to only five in wild brown trout. Furthermore, the use of farmed fish eliminates the risk of migration, which may otherwise bias the data when wild fish are used. © 2010 Wiley Periodicals, Inc.

Potentiating effect of graphene nanomaterials on aromatic environmental pollutant-induced cytochrome P450 1A expression in the topminnow fish hepatoma cell line PLHC-1.

PubMed

Lammel, Tobias; Boisseaux, Paul; Navas, José M

2015-09-01

Graphene and its derivatives are an emerging class of carbon nanomaterial with great potential for a broad range of industrial and consumer applications. However, their increasing production and use is expected to result in release of nano-sized graphene platelets into the environment, where they may interact with chemical pollutants modifying their fate and toxic potential. The objective of this study was to assess whether graphene nanoplatelets can act as vector for aromatic environmental pollutants increasing their cellular uptake and associated hazardous effects in vitro. For this purpose, cell cultures of the topminnow fish (Poeciliopsis lucida) hepatoma cell line PLHC-1 were simultaneously (and successively) exposed to graphene nanoplatelets (graphene oxide (GO) or carboxyl graphene (CXYG)) and an aryl hydrocarbon receptor (AhR) agonist (β-naphthoflavone (β-NF), benzo(k)fluoranthene (BkF) or 3,3',4,4',5,5'-hexachlorobiphenyl (PCB169)). Following exposure cytochrome P450 1A (Cyp1A) induction was assessed by measuring cyp1A mRNA expression levels using reverse transcriptase-quantitative polymerase chain reaction (RT-qPCR) and Cyp1A-dependent ethoxyresorufin-O-deethylase (EROD) activity. It was observed that pre- and co-exposure of cells to GO and CXYG nanoplatelets had a potentiating effect on β-NF, BkF, and PCB169-dependent Cyp1A induction suggesting that graphene nanoplatelets increase the effective concentration of AhR agonists by facilitating their passive diffusion into the cells by damaging the cells' plasma membrane and/or by transporting them over the plasma membrane via a Trojan horse-like mechanism. The results demonstrate the existence of combination effects between nanomaterials and environmental pollutants and stress the importance of considering these effects when evaluating their respective hazard. © 2014 Wiley Periodicals, Inc.

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

Photodecolorisation of melanoidins in vinasse with illuminated TiO2-ZnO/activated carbon composite.

PubMed

Otieno, Benton O; Apollo, Seth O; Naidoo, Bobby E; Ochieng, Aoyi

2017-06-07

A hybrid photo-catalyst, TiO 2 -ZnO, was synthesized by immobilizing ZnO on commercial TiO 2 (aeroxide P25). Activated carbon (AC) was subsequently used to support the hybrid, thus forming a TiO 2 -ZnO/AC composite catalyst. Fourier transform infrared (FTIR) analysis and scanning electron microscopy integrated with energy-dispersive X-ray spectroscopy (SEM-EDX) investigations revealed successful catalyst synthesis. Optical properties of the hybrid determined from photoluminescence (PL) and Ultraviolet-visible (UV-vis) spectroscopy confirmed a restrained recombination of electron-hole pairs and reduced energy band gap due to a successful heterojunction formation. The prepared catalysts were used to photodecolorise vinasse in a 12-W UVC batch photoreactor. TiO 2 -ZnO had improved photocatalytic activity compared with TiO 2 and ZnO separately. On supporting the hybrid onto AC, both adsorption and photocatalytic activities were further enhanced with improved overall color removal of 86% from 68%. Photodecolorisation followed the pseudo-first-order reaction model with the rate constant ([Formula: see text]) observed decreasing from 0.0701 to 0.0436 min -1 on increasing the initial concentration from 5,000 to 14,000 ppm. The UV process was found to be 33-fold less energy intensive for color reduction as compared to total organic carbon (TOC) reduction. Formation of nitrates during the photodecolorisation process was attributed to the mineralization of nitrogen heteroatoms in the color-causing melanoidin compounds.

Enhanced visible light photocatalytic activity of sulfated CuO-Bi2O3 photocatalyst

NASA Astrophysics Data System (ADS)

Liu, Xinlu; Zeng, Jun; Zhong, Junbo; Li, Jianzhang

2015-09-01

Sulfate (SO4 2-)-modified CuO-Bi2O3 composite photocatalysts with different loadings of SO4 2- were prepared by a facile pore impregnating method using ammonium persulfate (NH4)2S2O8 solution. The surface parameters, structure, morphology, the response ability to light, the binding energy of Bi 4 f and O 1 s, the hydroxyl content on the surface and the separation rate of photoinduced hole-electron pairs were characterized by Brunauer-Emmett-Teller method, X-ray diffraction, scanning electron microscopy, UV-Vis diffuse reflectance spectroscopy, X-ray photoelectron spectroscopy and surface photovoltage spectroscopy, respectively. The results reveal that sulfating of CuO-Bi2O3 decreases the band gap, increases the hydroxyl content on the surface, the separation rate of photoinduced hole-electron pairs and the adsorption of Rhodamine B on the sulfated photocatalysts. The photocatalytic activity of SO4 2-/CuO-Bi2O3 for decolorization of Rhodamine B aqueous solution was evaluated. The result shows that when the molar ratio of S/Bi is 5 %, SO4 2-/CuO-Bi2O3 exhibits the best photocatalytic activity under visible light irradiation and the possible reason is discussed.

Improvement in LPG sensing response by surface activation of ZnO thick films with Cr2O3

NASA Astrophysics Data System (ADS)

Hastir, Anita; Virpal, Kaur, Jasmeet; Singh, Gurpreet; Kohli, Nipin; Singh, Onkar; Singh, Ravi Chand

2015-05-01

Liquefied Petroleum Gas (LPG) sensing response of pure and Cr2O3 activated ZnO has been investigated in this study. Zinc oxide was synthesized by co-precipitation route and deposited as a thick film on an alumina substrate. The surface of ZnO sensor was activated by chromium oxide on surface oxidation by chromium chloride. The concentration of chromium chloride solution used to activate the ZnO sensor surface has been varied from 0 to 5 %. It is observed that response to LPG has improved as compared to pure ZnO.

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"

Nd2O3-SiO2 nanocomposites: A simple sonochemical preparation, characterization and photocatalytic activity.

PubMed

Zinatloo-Ajabshir, Sahar; Mortazavi-Derazkola, Sobhan; Salavati-Niasari, Masoud

2018-04-01

Nd 2 O 3 -SiO 2 nanocomposites with enhanced photocatalytic activity have been obtained through simple and rapid sonochemical route in presence of putrescine as a new basic agent, for the first time. The influence of the mole ratio of Si:Nd, basic agent and ultrasonic power have been optimized to obtain the best Nd 2 O 3 -SiO 2 nanocomposites on shape, size and photocatalytic activity. The produced Nd 2 O 3 -SiO 2 nanocomposites have been characterized utilizing XRD, EDX, TEM, FT-IR, DRS and FESEM. Application of the as-formed Nd 2 O 3 -SiO 2 nano and bulk structures as photocatalyst with photodegradation of methyl violet contaminant under ultraviolet illumination was compared. Results demonstrated that SiO 2 has remarkable effect on catalytic performance of Nd 2 O 3 photocatalyst for decomposition. By introducing of SiO 2 to Nd 2 O 3 , decomposition efficiency of Nd 2 O 3 toward methyl violet contaminant under ultraviolet illumination was increased. Copyright © 2017 Elsevier B.V. All rights reserved.

Na2O-Al2O3 system: Activity of Na2O in (α + β)- and (β + β)-alumina

NASA Astrophysics Data System (ADS)

Kale, G. M.

1992-12-01

The activity of Na2O in a biphasic mixture of (α + β)-alumina has been measured in the temperature range of 700 to 1100 K using the solid-state galvanic cell: 11663_2007_Article_BF02656462_TeX2GIFE1.gif _{(1:1)}^{Pt,CO_2 + O_2 /Na_2 CO_3 /(α + β ) - alumin a//(Y_2 O_3 )ZrO_2 //In + In_2 O_3 ,Ta,Pt} Similarly, the activity of Na2O in a (β + β’’)-alumina two-phase mixture has been measured between 700 and 1100 K employing the galvanic cell: 11663_2007_Article_BF02656462_TeX2GIFE2.gif _{(1:1)}^{Pt,CO_2 + O_2 /Na_2 CO_3 /(β + β ) - alumin a//(Y_2 O_3 )ZrO_2 //In + In_2 O_3 ,Ta,Pt} The reversible electromotive force (emf ) of both the cells was found to vary linearly with temperature over the entire temperature range of measurement. From the measured reversible emf and auxiliary thermodynamic data for In2O2, Na2O, CO2 and Na2CO3 reported in the literature, the temperature dependence of the logarithm of activity of Na2O in (α + β)-alumina is obtained: 11663_2007_Article_BF02656462_TeX2GIFE3.gif log α _{Na_2 O} (α + β ) = 1.85 - 14,750/T(K)( ± 0.015)(700 ≤slant T ≤slant 1100) For (β + β'’)-alumina, 11663_2007_Article_BF02656462_TeX2GIFE4.gif log α _{Na_2 O} (β + β ) = 3.9 - 13,000/T(K)( ± 0.015)(700 ≤slant T ≤slant 1100)

The effect of ZnO addition on H2O activation over Co/ZrO2 catalysts

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

Davidson, Stephen D.; Sun, Junming; Wang, Yong

The effect of ZnO addition on the dissociation of H2O and subsequent effects on cobalt oxidation state and ethanol reaction pathway were investigated over Co/ZrO2 catalyst during ethanol steam reforming (ESR). Catalyst physical properties were characterized by BET, XRD, and TEM. To characterize the catalysts ability to dissociate H2O, Raman spectroscopy, H2O-TPO, and pulsed H2O oxidation coupled with H2-TPR were used. It was found that the addition of ZnO to cobalt supported on ZrO2 decreased the activity for H2O dissociation, leading to a lower degree of cobalt oxidation. The decreased H2O dissociation was also found to affect the reaction pathway,more » evidenced by a shift in liquid product selectivity away from acetone and towards acetaldehyde.« less

Dioxygen Activation and O–O Bond Formation Reactions by Manganese Corroles

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

Guo, Mian; Lee, Yong-Min; Gupta, Ranjana

Activation of dioxygen (O 2) in enzymatic and biomimetic reactions has been intensively investigated over the past several decades. More recently, O–O bond formation, which is the reverse of the O 2-activation reaction, has been the focus of current research. Herein, we report the O 2-activation and O–O bond formation reactions by manganese corrole complexes. In the O 2-activation reaction, Mn(V)-oxo and Mn(IV)-peroxo intermediates were formed when Mn(III) corroles were exposed to O 2 in the presence of base (e.g., OH –) and hydrogen atom (H atom) donor (e.g., THF or cyclic olefins); the O 2-activation reaction did not occurmore » in the absence of base and H atom donor. Moreover, formation of the Mn(V)-oxo and Mn(IV)-peroxo species was dependent on the amounts of base present in the reaction solution. The role of the base was proposed to lower the oxidation potential of the Mn(III) corroles, thereby facilitating the binding of O 2 and forming a Mn(IV)-superoxo species. The putative Mn(IV)-superoxo species was then converted to the corresponding Mn(IV)-hydroperoxo species by abstracting a H atom from H atom donor, followed by the O–O bond cleavage of the putative Mn(IV)-hydroperoxo species to form a Mn(V)-oxo species. We have also shown that addition of hydroxide ion to the Mn(V)-oxo species afforded the Mn(IV)-peroxo species via O–O bond formation and the resulting Mn(IV)-peroxo species reverted to the Mn(V)-oxo species upon addition of proton, indicating that the O–O bond formation and cleavage reactions between the Mn(V)-oxo and Mn(IV)-peroxo complexes are reversible. The present paper reports the first example of using the same manganese complex in both O 2-activation and O–O bond formation reactions.« less

Dioxygen Activation and O–O Bond Formation Reactions by Manganese Corroles

DOE PAGES

Guo, Mian; Lee, Yong-Min; Gupta, Ranjana; ...

2017-10-22

Activation of dioxygen (O 2) in enzymatic and biomimetic reactions has been intensively investigated over the past several decades. More recently, O–O bond formation, which is the reverse of the O 2-activation reaction, has been the focus of current research. Herein, we report the O 2-activation and O–O bond formation reactions by manganese corrole complexes. In the O 2-activation reaction, Mn(V)-oxo and Mn(IV)-peroxo intermediates were formed when Mn(III) corroles were exposed to O 2 in the presence of base (e.g., OH –) and hydrogen atom (H atom) donor (e.g., THF or cyclic olefins); the O 2-activation reaction did not occurmore » in the absence of base and H atom donor. Moreover, formation of the Mn(V)-oxo and Mn(IV)-peroxo species was dependent on the amounts of base present in the reaction solution. The role of the base was proposed to lower the oxidation potential of the Mn(III) corroles, thereby facilitating the binding of O 2 and forming a Mn(IV)-superoxo species. The putative Mn(IV)-superoxo species was then converted to the corresponding Mn(IV)-hydroperoxo species by abstracting a H atom from H atom donor, followed by the O–O bond cleavage of the putative Mn(IV)-hydroperoxo species to form a Mn(V)-oxo species. We have also shown that addition of hydroxide ion to the Mn(V)-oxo species afforded the Mn(IV)-peroxo species via O–O bond formation and the resulting Mn(IV)-peroxo species reverted to the Mn(V)-oxo species upon addition of proton, indicating that the O–O bond formation and cleavage reactions between the Mn(V)-oxo and Mn(IV)-peroxo complexes are reversible. The present paper reports the first example of using the same manganese complex in both O 2-activation and O–O bond formation reactions.« less

Enhanced the hydrophobic surface and the photo-activity of TiO2-SiO2 composites

NASA Astrophysics Data System (ADS)

Wahyuni, S.; Prasetya, A. T.

2017-02-01

The aim of this research is to develop nanomaterials for coating applications. This research studied the effect of various TiO2-SiO2 composites in acrylic paint to enhance the hydrophobic properties of the substrate. Titanium dioxide containing silica in the range 20-35 mol% has been synthesized using sol-gel route. The XRD’s spectra show that increasing SiO2 content in the composite, decreasing its crystalline properties but increasing the surface area. TiO2-SiO2 composite was dispersed in acrylic paint in 2% composition by weight. The largest contact angle was 70, which produced by the substrate coated with TS-35-modified acrylic paint. This study also investigated the enhanced photo-activity of TiO2-SiO2 modified with poly-aniline. The XRD spectra show that the treatment does not change the crystal structure of TiO2. The photo-activity of the composite was evaluated by degradation of Rhodamine-B with visible light. The best performance of the degradation process was handled by the composite treated with 0.1mL anilines per gram of TiO2-SiO2 composite (TSP-A). On the other side, the contact angle 70 has not shown an excellent hydrophobic activity. However, the AFM spectra showed that nanoroughness has started to form on the surface of acrylic paint modified with TiO2-SiO2 than acrylic alone.

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

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. Copyright © 2014 Elsevier B.V. All rights reserved.

Activity coefficients of NiO and CoO in CaO-Al2O3-SiO2 slag and their application to the recycling of Ni-Co-Fe-based end-of-life superalloys via remelting

NASA Astrophysics Data System (ADS)

Lu, Xin; Miki, Takahiro; Nagasaka, Tetsuya

2017-01-01

To design optimal pyrometallurgical processes for nickel and cobalt recycling, and more particularly for the end-of-life process of Ni-Co-Fe-based end-of-life (EoL) superalloys, knowledge of their activity coefficients in slags is essential. In this study, the activity coefficients of NiO and CoO in CaO-Al2O3-SiO2 slag, a candidate slag used for the EoL superalloy remelting process, were measured using gas/slag/metal equilibrium experiments. These activity coefficients were then used to consider the recycling efficiency of nickel and cobalt by remelting EoL superalloys using CaO-Al2O3-SiO2 slag. The activity coefficients of NiO and CoO in CaO-Al2O3-SiO2 slag both show a positive deviation from Raoult's law, with values that vary from 1 to 5 depending on the change in basicity. The activity coefficients of NiO and CoO peak in the slag with a composition near B = (%CaO)/(%SiO2) = 1, where B is the basicity. We observed that controlling the slag composition at approximately B = 1 effectively reduces the cobalt and nickel oxidation losses and promotes the oxidation removal of iron during the remelting process of EoL superalloys.

Evaluation of Bajo Blanco Sandbar as a Potential Beach Nourishment Borrow Site for Eroding Beaches in Rincon, Puerto Rico

NASA Astrophysics Data System (ADS)

Rojas, C. A.; Canals, M.

2016-02-01

The municipality of Rincón, Puerto Rico is recognized for its world-class surfing beaches. Unfortunately, the coast from Punta Higüero to Punta Cadena in Rincón is experiencing long-term erosion (Thieler 2007), which has caused the destruction of many beachfront homes and hotels and had negative impacts on the local tourism-driven economy. The purpose of this project is to evaluate whether the nearby Bajo Blanco sandbar, located just offshore of these eroded beaches, could be used as a possible beach nourishment borrow site. A high-resolution bathymetric survey of Bajo Blanco sandbar was conducted along with a grain size analysis to compare the grain size distribution of the Bajo Blanco sandbar with the sediment properties of the eroded beaches. It was found that the sediment from Bajo Blanco is finer yet may be suitable as beach fill material for these beaches according to Dean's overfill ratio. Compatibility analysis suggests a total volume of sandbar sediment of approximately 685,555 cubic meters to allow successful beach equilibrium. To evaluate the potential effects of the sand extraction on the nearshore wave climate, numerical simulations were performed using the spectral wave model of the USACE Coastal Modeling System (CMS-Wave). Wave model results for several dredging scenarios suggest that wave energy flux concentrates around the shoal causing an increase in wave height at the northern and southern edges of the shoal. Therefore, conservation of energy leads to a reduction of wave energy flux shoreward of the shoal, causing a shadow of reduced wave height. In addition, the Tres Palmas Marine reserve is located just north of Bajo Blanco sandbar and features some of the healthiest Elkorn Corals in the Caribbean. To avoid excessive sedimentation of these reefs during dredging activities, the Particle Tracking Module (PTM), integrated in the Surface-water Modeling System (SMS), was used to evaluate the Lagrangian particle transport processes along Bajo

Preparation and catalytic activities of LaFeO3 and Fe2O3 for HMX thermal decomposition.

PubMed

Wei, Zhi-Xian; Xu, Yan-Qing; Liu, Hai-Yan; Hu, Chang-Wen

2009-06-15

Perovskite-type LaFeO(3) and alpha-Fe(2)O(3) with high specific surface areas were directly prepared with appropriate stearic acid-nitrates ratios by a novel stearic acid solution combustion method. The obtained powders were characterized by XRD, FT-IR and XPS techniques. The catalytic activities of perovskite-type LaFeO(3) and alpha-Fe(2)O(3) for the thermal decomposition of octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) were investigated by TG and TG-EGA techniques. The experimental results show that the catalytic activity of perovskite-type LaFeO(3) was much higher than that of alpha-Fe(2)O(3) because of higher concentration of surface-adsorbed oxygen (O(ad)) and hydroxyl of LaFeO(3). The study points out a potential way to develop new and more active perovskite-type catalysts for the HMX thermal decomposition.

The properties of ZnO nanofluids and the role of H2O2 in the disinfection activity against Escherichia coli.

PubMed

Zhang, Lingling; Li, Yu; Liu, Xiaoming; Zhao, Lihua; Ding, Yulong; Povey, Malcolm; Cang, Daqiang

2013-08-01

This work investigates the disinfection property of ZnO nanofluids, focusing on H2O2 production and the disinfection activities of ZnO suspensions with different particles/aggregates. The possible disinfection mechanisms of ZnO suspensions are analysed. In this work, a medium mill was used to produce ZnO suspensions with different sizes of particles/aggregates. During the milling process, five ZnO suspension samples (A-E) were produced. X-ray Diffraction (XRD) and Dynamic Light Scattering (DLS) analyses revealed that after milling, the size of ZnO particles/aggregates in the suspensions decreased. Disinfection tests, H2O2 detection assays and fluorescent analyses were used to explore the disinfection activities and mechanism of ZnO suspensions. Disinfection tests results showed that all the produced ZnO suspension exhibited disinfection activity against Escherichia coli. ZnO suspensions with smaller particles/aggregates showed better disinfection activities. The presence of H2O2 in ZnO suspension was analysed. The H2O2 detection assay suggested that there is 1 μM H2O2 in 0.2 g/l ZnO Sample A, while there was no H2O2 present in ZnO Sample E. Though results showed that there was no H2O2 present in ZnO Sample E, Sample E with a size of 93 nm showed the best disinfection activities. Fluorescence tests detected that the interaction between E. coli lipid vesicles and ZnO Sample E was much faster and more efficient. This study firstly demonstrated that ZnO suspensions with different particles/aggregates produced different amount of H2O2. Results suggested that H2O2 is responsible for the disinfection activity of larger ZnO particles/aggregates while the interaction between smaller ZnO particles/aggregates and vesicle lipids is responsible for the disinfection activity of smaller ZnO particles/aggregates. Crown Copyright © 2013. Published by Elsevier Ltd. All rights reserved.

Destructive adsorption of Diazinon pesticide by activated carbon nanofibers containing Al2O3 and MgO nanoparticles.

PubMed

Behnam, Roghaye; Morshed, Mohammad; Tavanai, Hossein; Ghiaci, Mehran

2013-10-01

We report the destructive adsorption of Diazinon pesticide by porous webs of activated carbon nanofibers containing Al2O3 and MgO nanoparticles. The results show that, the presence of Al2O3 and MgO nanoparticles in the activated carbon nanofibers increases the amount of destructively adsorbed Diazinon pesticide by activated carbon nanofibers. Moreover, type, amount, and specific surface area of metal oxide nanoparticles affect the adsorption rate as well as the total destructively adsorbed Diazinon. Liquid chromatography proved the degradation of Diazinon by chemical reaction with Al2O3 and MgO nanoparticles. Liquid chromatography-mass spectrometry showed that the main product of reaction between Diazinon and the metal oxides is 2-isopropyl-6-methyl-4-pyrimidinol with less toxicity than Diazinon.

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.

Enhanced Activity and Durability of Nanosized Pt-SnO2/IrO2/CNTs Catalyst for Methanol Electrooxidation.

PubMed

Wang, Hongjuan; Wang, Xiaohui; Zheng, Jiadao; Peng, Feng; Yu, Hao

2015-05-01

Pt-SnO2/IrO2/CNTs anode catalyst for direct methanol fuel cell was designed and prepared with IrO2/CNTs as support for the subsequent immobilization of Pt and SnO2 at the same time. The structure of the catalysts and their catalytic performance in methanol electrooxidation were investigated and the roles of IrO2 and SnO2 in methanol electrooxidation were discussed as well. Results show that Pt-SnO2/IrO2/CNTs catalyst exhibits the best activity and durability for methanol electrooxidation when compared with Pt/CNTs, Pt/IrO2/CNTs and Pt-SnO2/CNTs. According to the results of electrochemical tests and physicochemical characterizations, the enhancements of Pt-SnO2/IrO2/CNTs were attributed to the special properties of IrO2 and SnO2, in which IrO2 mainly increases the methanol oxidation activity and SnO2 mainly improves the CO oxidation ability and durability. Therefore, Pt-SnO2/IrO2/CNTs exhibits excellent performance for methanol oxidation with higher electrocatalytic activity (I(f) of 1054 A g(Pt(-1)) and powerful anti-poisoning ability (the onset potential for CO oxidation of 0.3 V) and outstanding durability (the sustained time t in CP of 617 s), revealing a suitable anode catalyst for DMFCs.

Synthesis, characterization, and antibacterial activity of N,O-quaternary ammonium chitosan.

PubMed

Xu, Tao; Xin, Meihua; Li, Mingchun; Huang, Huili; Zhou, Shengquan; Liu, Juezhao

2011-11-08

N,N,N-Trimethyl O-(2-hydroxy-3-trimethylammonium propyl) chitosans (TMHTMAPC) with different degrees of O-substitution were synthesized by reacting O-methyl-free N,N,N-trimethyl chitosan (TMC) with 3-chloro-2-hydroxy-propyl trimethyl ammonium chloride (CHPTMAC). The products were characterized by (1)H NMR, FTIR and TGA, and investigated for antibacterial activity against Staphylococcus aureus and Escherichia coli under weakly acidic (pH 5.5) and weakly basic (pH 7.2) conditions. TMHTMAPC exhibited enhanced antibacterial activity compared with TMC, and the activity of TMHTMAPC increased with an increase in the degree of substitution. Divalent cations (Ba(2+) and Ca(2+)) strongly reduced the antibacterial activity of chitosan, O-carboxymethyl chitosan and N,N,N-trimethyl-O-carboxymethyl chitosan, but the repression on the antibacterial activity of TMC and TMHTMAPC was weaker. This indicates that the free amino group on chitosan backbone is the main functional group interacting with divalent cations. The existence of 100 mM Na(+) slightly reduced the antibacterial activity of both chitosan and its derivatives. Copyright © 2011 Elsevier Ltd. All rights reserved.

NeuA sialic acid O-acetylesterase activity modulates O-acetylation of capsular polysaccharide in group B Streptococcus.

PubMed

Lewis, Amanda L; Cao, Hongzhi; Patel, Silpa K; Diaz, Sandra; Ryan, Wesley; Carlin, Aaron F; Thon, Vireak; Lewis, Warren G; Varki, Ajit; Chen, Xi; Nizet, Victor

2007-09-21

Group B Streptococcus (GBS) is a common cause of neonatal sepsis and meningitis. A major GBS virulence determinant is its sialic acid (Sia)-capped capsular polysaccharide. Recently, we discovered the presence and genetic basis of capsular Sia O-acetylation in GBS. We now characterize a GBS Sia O-acetylesterase that modulates the degree of GBS surface O-acetylation. The GBS Sia O-acetylesterase operates cooperatively with the GBS CMP-Sia synthetase, both part of a single polypeptide encoded by the neuA gene. NeuA de-O-acetylation of free 9-O-acetyl-N-acetylneuraminic acid (Neu5,9Ac(2)) was enhanced by CTP and Mg(2+), the substrate and co-factor, respectively, of the N-terminal GBS CMP-Sia synthetase domain. In contrast, the homologous bifunctional NeuA esterase from Escherichia coli K1 did not display cofactor dependence. Further analyses showed that in vitro, GBS NeuA can operate via two alternate enzymatic pathways: de-O-acetylation of Neu5,9Ac(2) followed by CMP activation of Neu5Ac or activation of Neu5,9Ac(2) followed by de-O-acetylation of CMP-Neu5,9Ac(2). Consistent with in vitro esterase assays, genetic deletion of GBS neuA led to accumulation of intracellular O-acetylated Sias, and overexpression of GBS NeuA reduced O-acetylation of Sias on the bacterial surface. Site-directed mutagenesis of conserved asparagine residue 301 abolished esterase activity but preserved CMP-Sia synthetase activity, as evidenced by hyper-O-acetylation of capsular polysaccharide Sias on GBS expressing only the N301A NeuA allele. These studies demonstrate a novel mechanism regulating the extent of capsular Sia O-acetylation in intact bacteria and provide a genetic strategy for manipulating GBS O-acetylation in order to explore the role of this modification in GBS pathogenesis and immunogenicity.

Electrocatalytic activity of LaNiO3 toward H2O2 reduction reaction: Minimization of oxygen evolution

NASA Astrophysics Data System (ADS)

Amirfakhri, Seyed Javad; Meunier, Jean-Luc; Berk, Dimitrios

2014-12-01

The catalytic activity of LaNiO3 toward H2O2 reduction reaction (HPRR), with a potential application in the cathode side of fuel cells, is studied in alkaline, neutral and acidic solutions by rotating disk electrode. The LaNiO3 particles synthesised by citrate-based sol-gel method have sizes between 30 and 70 nm with an active specific surface area of 1.26 ± 0.05 m2 g-1. LaNiO3 shows high catalytic activity toward HPRR in 0.1 M KOH solution with an exchange current density based on the active surface area (j0A) of (7.4 ± 1) × 10-6 A cm-2 which is noticeably higher than the j0A of N-doped graphene. The analysis of kinetic parameters suggests that the direct reduction of H2O2, H2O2 decomposition, O2 reduction and O2 desorption occur through HPRR on this catalyst. In order to control and minimize oxygen evolution from the electrode surface, the effects of catalyst loading, bulk concentration of H2O2, and using a mixture of LaNiO3 and N-doped graphene are studied. Although the mechanism of HPRR is independent of the aforementioned operating conditions, gas evolution decreases by increasing the catalyst loading, decreasing the bulk concentration of H2O2, and addition of N-doped graphene to LaNiO3.

Synthesis, characteristics and antimicrobial activity of ZnO nanoparticles

NASA Astrophysics Data System (ADS)

Janaki, A. Chinnammal; Sailatha, E.; Gunasekaran, S.

2015-06-01

The utilization of various plant resources for the bio synthesis of metallic nano particles is called green technology and it does not utilize any harmful protocols. Present study focuses on the green synthesis of ZnO nano particles by Zinc Carbonate and utilizing the bio-components of powder extract of dry ginger rhizome (Zingiber officinale). The ZnO nano crystallites of average size range of 23-26 nm have been synthesized by rapid, simple and eco friendly method. Zinc oxide nano particles were characterized by using X-ray diffraction (XRD), Scanning Electron Microscope (SEM), Energy Dispersive X-ray spectroscopy (EDX). FTIR spectra confirmed the adsorption of surfactant molecules at the surface of ZnO nanoparticles and the presence of ZnO bonding. Antimicrobial activity of ZnO nano particles was done by well diffusion method against pathogenic organisms like Klebsiella pneumonia, Staphylococcus aureus and Candida albicans and Penicillium notatum. It is observed that the ZnO synthesized in the process has the efficient antimicrobial activity.

Eroding dipoles and vorticity growth for Euler flows in {{{R}}}^{3}: the hairpin geometry as a model for finite-time blowup

NASA Astrophysics Data System (ADS)

Childress, Stephen; Gilbert, Andrew D.

2018-02-01

A theory of an eroding ‘hairpin’ vortex dipole structure in three-dimensions is developed, extending our previous study of an axisymmetric eroding dipole without swirl. The axisymmetric toroidal dipole was found to lead to maximal growth of vorticity, as {t}4/3. The hairpin is here similarly proposed as a model to produce large ‘self-stretching’ of vorticity, with the possibility of finite-time blow-up. We derive a system of partial differential equations of ‘generalized’ form, involving contour averaging of a locally two-dimensional Euler flow. We do not attempt here to solve the system exactly, but point out that non-existence of physically acceptable solutions would most probably be a result of the axial flow. Because of the axial flow the vorticity distribution within the dipole eddies is no longer of the simple Sadovskii type (vorticity constant over a cross-section) obtained in the axisymmetric problem. Thus the solution of the system depends upon the existence of a larger class of propagating two-dimensional dipoles. The hairpin model is obtained by formal asymptotic analysis. As in the axisymmetric problem a local transformation to ‘shrinking’ coordinates is introduced, but now in a self-similar form appropriate to the study of a possible finite-time singularity. We discuss some properties of the model, including a study of the helicity and a first step in iterating toward a solution from the Sadovskii structure. We also present examples of two-dimensional propagating dipoles not previously studied, which have a vorticity profile consistent with our model. Although no rigorous results can be given, and analysis of the system is only partial, the formal calculations are consistent with the possibility of a finite time blowup of vorticity at a point of vanishing circulation of the dipole eddies, but depending upon the existence of the necessary two-dimensional propagating dipole. Our results also suggest that conservation of kinetic energy as

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.

High photocatalytic activity of Fe2O3/TiO2 nanocomposites prepared by photodeposition for degradation of 2,4-dichlorophenoxyacetic acid.

PubMed

Lee, Shu Chin; Lintang, Hendrik O; Yuliati, Leny

2017-01-01

Two series of Fe 2 O 3 /TiO 2 samples were prepared via impregnation and photodeposition methods. The effect of preparation method on the properties and performance of Fe 2 O 3 /TiO 2 for photocatalytic degradation of 2,4-dichlorophenoxyacetic acid (2,4-D) under UV light irradiation was examined. The Fe 2 O 3 /TiO 2 nanocomposites prepared by impregnation showed lower activity than the unmodified TiO 2 , mainly due to lower specific surface area caused by heat treatment. On the other hand, the Fe 2 O 3 /TiO 2 nanocomposites prepared by photodeposition showed higher photocatalytic activity than the unmodified TiO 2 . Three times higher photocatalytic activity was obtained on the best photocatalyst, Fe 2 O 3 (0.5)/TiO 2 . The improved activity of TiO 2 after photodeposition of Fe 2 O 3 was contributed to the formation of a heterojunction between the Fe 2 O 3 and TiO 2 nanoparticles that improved charge transfer and suppressed electron-hole recombination. A further investigation on the role of the active species on Fe 2 O 3 /TiO 2 confirmed that the crucial active species were both holes and superoxide radicals. The Fe 2 O 3 (0.5)/TiO 2 sample also showed good stability and reusability, suggesting its potential for water purification applications.

Synthesis and catalytic activity of electrospun NiO/NiCo2O4 nanotubes for CO and acetaldehyde oxidation

NASA Astrophysics Data System (ADS)

Kim, Il Hee; Lee, Hyerim; Yu, Areum; Jeong, Jae Hwan; Lee, Youngmi; Kim, Myung Hwa; Lee, Chongmok; Dok Kim, Young

2018-04-01

NiO/NiCo2O4 nanotubes with a diameter of approximately 100 nm are synthesized using Ni and Co precursors via electro-spinning and subsequent calcination processes. The tubular structure is confirmed via transmission electron microscopy imaging, whereas the structures and elemental compositions of the nanotubes are determined using x-ray diffraction, energy dispersive x-ray spectroscopy, and x-ray photoelectron spectroscopy. N2 adsorption isotherm data reveal that the surface of the nanotubes consists of micropores, thereby resulting in a significantly higher surface area (˜20 m2 g-1) than expected for a flat-surface structure (<15 m2 g-1). Herein, we present a study of the catalytic activity of our novel NiO/NiCo2O4 nanotubes for CO and acetaldehyde oxidation. The catalytic activity of NiO/NiCo2O4 is superior to Pt below 100 °C for CO oxidation. For acetaldehyde oxidation, the total oxidation activity of NiO/NiCo2O4 for acetaldehyde is comparable with that of Pt. Coexistence of many under-coordinated Co and Ni active sites in our structure is suggested be related to the high catalytic activity. It is suggested that our novel NiO/NiCo2O4 tubular structures with surface microporosity can be of interest for a variety of applications, including the catalytic oxidation of harmful gases.

Synthesis and catalytic activity of electrospun NiO/NiCo2O4 nanotubes for CO and acetaldehyde oxidation.

PubMed

Kim, Il Hee; Lee, Hyerim; Yu, Areum; Jeong, Jae Hwan; Lee, Youngmi; Kim, Myung Hwa; Lee, Chongmok; Kim, Young Dok

2018-04-27

NiO/NiCo 2 O 4 nanotubes with a diameter of approximately 100 nm are synthesized using Ni and Co precursors via electro-spinning and subsequent calcination processes. The tubular structure is confirmed via transmission electron microscopy imaging, whereas the structures and elemental compositions of the nanotubes are determined using x-ray diffraction, energy dispersive x-ray spectroscopy, and x-ray photoelectron spectroscopy. N 2 adsorption isotherm data reveal that the surface of the nanotubes consists of micropores, thereby resulting in a significantly higher surface area (∼20 m 2 g -1 ) than expected for a flat-surface structure (<15 m 2 g -1 ). Herein, we present a study of the catalytic activity of our novel NiO/NiCo 2 O 4 nanotubes for CO and acetaldehyde oxidation. The catalytic activity of NiO/NiCo 2 O 4 is superior to Pt below 100 °C for CO oxidation. For acetaldehyde oxidation, the total oxidation activity of NiO/NiCo 2 O 4 for acetaldehyde is comparable with that of Pt. Coexistence of many under-coordinated Co and Ni active sites in our structure is suggested be related to the high catalytic activity. It is suggested that our novel NiO/NiCo 2 O 4 tubular structures with surface microporosity can be of interest for a variety of applications, including the catalytic oxidation of harmful gases.

Kinetics and equilibrium models for the sorption of tributyltin to nZnO, activated carbon and nZnO/activated carbon composite in artificial seawater.

PubMed

Ayanda, Olushola S; Fatoki, Olalekan S; Adekola, Folahan A; Ximba, Bhekumusa J

2013-07-15

The removal of tributyltin (TBT) from artificial seawater using nZnO, activated carbon and nZnO/activated carbon composite was systematically studied. The equilibrium and kinetics of adsorption were investigated in a batch adsorption system. Equilibrium adsorption data were analyzed using Langmuir, Freundlich, Temkin and Dubinin-Radushkevich (D-R) isotherm models. Pseudo first- and second-order, Elovich, fractional power and intraparticle diffusion models were applied to test the kinetic data. Thermodynamic parameters such as ΔG°, ΔS° and ΔH° were also calculated to understand the mechanisms of adsorption. Optimal conditions for the adsorption of TBT from artificial seawater were then applied to TBT removal from natural seawater. A higher removal efficiency of TBT (>99%) was obtained for the nZnO/activated carbon composite material and for activated carbon but not for nZnO. Copyright © 2013 Elsevier Ltd. All rights reserved.

Microbial oxidation of lithospheric organic carbon in rapidly eroding tropical mountain soils.

PubMed

Hemingway, Jordon D; Hilton, Robert G; Hovius, Niels; Eglinton, Timothy I; Haghipour, Negar; Wacker, Lukas; Chen, Meng-Chiang; Galy, Valier V

2018-04-13

Lithospheric organic carbon ("petrogenic"; OC petro ) is oxidized during exhumation and subsequent erosion of mountain ranges. This process is a considerable source of carbon dioxide (CO 2 ) to the atmosphere over geologic time scales, but the mechanisms that govern oxidation rates in mountain landscapes are poorly constrained. We demonstrate that, on average, 67 ± 11% of the OC petro initially present in bedrock exhumed from the tropical, rapidly eroding Central Range of Taiwan is oxidized in soils, leading to CO 2 emissions of 6.1 to 18.6 metric tons of carbon per square kilometer per year. The molecular and isotopic evolution of bulk OC and lipid biomarkers during soil formation reveals that OC petro remineralization is microbially mediated. Rapid oxidation in mountain soils drives CO 2 emission fluxes that increase with erosion rate, thereby counteracting CO 2 drawdown by silicate weathering and biospheric OC burial. Copyright © 2018 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.

A highly active and stable IrO x/SrIrO 3 catalyst for the oxygen evolution reaction

DOE PAGES

Seitz, Linsey C.; Dickens, Colin F.; Nishio, Kazunori; ...

2016-09-02

Oxygen electrochemistry plays a key role in renewable energy technologies such as fuel cells and electrolyzers, but the slow kinetics of the oxygen evolution reaction (OER) limit the performance and commercialization of such devices. Here we report an iridium oxide/strontium iridium oxide (IrO x/SrIrO 3) catalyst formed during electrochemical testing by strontium leaching from surface layers of thin films of SrIrO 3. This catalyst has demonstrated specific activity at 10 milliamps per square centimeter of oxide catalyst (OER current normalized to catalyst surface area), with only 270 to 290 millivolts of overpotential for 30 hours of continuous testing in acidicmore » electrolyte. Here, density functional theory calculations suggest the formation of highly active surface layers during strontium leaching with IrO 3 or anatase IrO 2 motifs. The IrO x/SrIrO 3 catalyst outperforms known IrO x and ruthenium oxide (RuO x) systems, the only other OER catalysts that have reasonable activity in acidic electrolyte.« less

O-GlcNAc modification of PPAR{gamma} reduces its transcriptional activity

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

Ji, Suena; Park, Sang Yoon; Roth, Juergen

2012-01-27

Highlights: Black-Right-Pointing-Pointer We found that PPAR{gamma} is modified by O-GlcNAc in 3T3-L1 adipocytes. Black-Right-Pointing-Pointer The Thr54 of PPAR{gamma}1 is the major O-GlcNAc site. Black-Right-Pointing-Pointer Transcriptional activity of PPAR{gamma}1 was decreased on treatment with the OGA inhibitor. -- Abstract: The peroxisome proliferator-activated receptor {gamma} (PPAR{gamma}), a member of the nuclear receptor superfamily, is a key regulator of adipogenesis and is important for the homeostasis of the adipose tissue. The {beta}-O-linked N-acetylglucosamine (O-GlcNAc) modification, a posttranslational modification on various nuclear and cytoplasmic proteins, is involved in the regulation of protein function. Here, we report that PPAR{gamma} is modified by O-GlcNAc in 3T3-L1more » adipocytes. Mass spectrometric analysis and mutant studies revealed that the threonine 54 of the N-terminal AF-1 domain of PPAR{gamma} is the major O-GlcNAc site. Transcriptional activity of wild type PPAR{gamma} was decreased 30% by treatment with the specific O-GlcNAcase (OGA) inhibitor, but the T54A mutant of PPAR{gamma} did not respond to inhibitor treatment. In 3T3-L1 cells, an increase in O-GlcNAc modification by OGA inhibitor reduced PPAR{gamma} transcriptional activity and terminal adipocyte differentiation. Our results suggest that the O-GlcNAc state of PPAR{gamma} influences its transcriptional activity and is involved in adipocyte differentiation.« less

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.

Cytotoxicity of the dicarboximide fungicides, vinclozolin and iprodione, in rat hepatoma-derived Fa32 cells.

PubMed

Dierickx, Paul J

2004-10-01

Dicarboximide fungicides are widely used to control various fungal species. Their primary action is not known, due to a lack of knowledge concerning the mechanism of action of the dicarboximide group. The cytotoxicities of vinclozolin and iprodione in rat hepatoma-derived Fa32 cells were investigated. Cytotoxicity was measured by neutral red uptake inhibition after treatment for 24 hours. Iprodione was more toxic than vinclozolin. Vinclozolin was less toxic in glutathione-depleted cells than in control cells. This was also true for iprodione at lower concentrations, but iprodione became more toxic at higher concentrations. Both the fungicides increased the endogenous glutathione content by 20% after 1 hour. After 24 hours, the glutathione content was doubled by vinclozolin, but was not affected by iprodione. No effect on glutathione S-transferase activity or reactive oxygen species formation could be observed. Cytochrome P450-dependent ethoxyresorufin-O-deethylase and pentoxyresorufin-O-depentylase activities were moderately activated by iprodione and strongly activated by vinclozolin. A glutathione-related cytochrome P450-dependent metabolic attack of vinclozolin and iprodione could be responsible for their cytotoxicity in Fa32 cells. Further research is needed to fully elucidate these (or other) mechanisms.

The protective activity of tea against infection by Vibrio cholerae O1.

PubMed

Toda, M; Okubo, S; Ikigai, H; Suzuki, T; Suzuki, Y; Shimamura, T

1991-02-01

Extracts of black tea exhibited bactericidal activity against Vibrio cholerae O1. The tea extract inhibited the haemolysin activity of V. cholerae O1, El Tor and the morphological changes of Chinese hamster ovary cells induced by cholera toxin. Tea extract also reduced fluid accumulation induced by cholera toxin in sealed adult mice and by V. cholerae O1 in ligated intestinal loops of rabbits. These findings suggest that tea has protective activity against V. cholerae O1.

TiO2 film/Cu2O microgrid heterojunction with photocatalytic activity under solar light irradiation.

PubMed

Zhang, Junying; Zhu, Hailing; Zheng, Shukai; Pan, Feng; Wang, Tianmin

2009-10-01

Coupling a narrow-band-gap semiconductor with TiO(2) is an effective method to produce photocatalysts that work under UV-vis light irradiation. Usually photocatalytic coupled-semiconductors exist mainly as powders, and photocatalytic activity is only favored when a small loading amount of narrow-band-gap semiconductor is used. Here we propose a heavy-loading photocatalyst configuration in which 51% of the surface of the TiO(2) film is covered by a Cu(2)O microgrid. The coupled system shows higher photocatalytic activity under solar light irradiation than TiO(2) and Cu(2)O films. This improved performance is due to the efficient charge transfer between the two phases and the similar opportunity each has to be exposed to irradiation and adsorbates.

Reduced cytochrome P4501A activity and recovery from oxidative stress during subchronic benzo[a]pyrene and benzo[e]pyrene treatment of rainbow trout

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

Curtis, Lawrence R., E-mail: larry.curtis@oregonstate.edu; Garzon, Claudia B.; Arkoosh, Mary

2011-07-01

This study assessed the role of aryl hydrocarbon receptor (AHR) affinity, and cytochrome P4501A (CYP1A) protein and activity in polyaromatic hydrocarbon (PAH)-induced oxidative stress. In the 1-100 nM concentration range benzo[a]pyrene (BaP) but not benzo[e]pyrene (BeP) competitively displaced 2 nM [{sup 3}H]2, 3, 7, 8-tetrachloro-dibenzo-p-dioxin from rainbow trout AHR2{alpha}. Based on appearance of fluorescent aromatic compounds in bile over 3, 7, 14, 28 or 50 days of feeding 3 {mu}g of BaP or BeP/g fish/day, rainbow trout liver readily excreted these polyaromatic hydrocarbons (PAHs) and their metabolites at near steady state rates. CYP1A proteins catalyzed more than 98% of ethoxyresorufin-O-deethylasemore » (EROD) activity in rainbow trout hepatic microsomes. EROD activity of hepatic microsomes initially increased and then decreased to control activities after 50 days of feeding both PAHs. Immunohistochemistry of liver confirmed CYP1A protein increased in fish fed both PAHs after 3 days and remained elevated for up to 28 days. Neither BaP nor BeP increased hepatic DNA adduct concentrations at any time up to 50 days of feeding these PAHs. Comet assays of blood cells demonstrated marked DNA damage after 14 days of feeding both PAHs that was not significant after 50 days. There was a strong positive correlation between hepatic EROD activity and DNA damage in blood cells over time for both PAHs. Neither CYP1A protein nor 3-nitrotyrosine (a biomarker for oxidative stress) immunostaining in trunk kidney were significantly altered by BaP or BeP after 3, 7, 14, or 28 days. There was no clear association between AHR2{alpha} affinity and BaP and BeP-induced oxidative stress. - Highlights: > No direct association between aryl hydrocarbon receptor affinity and polyaromatic hydrocarbon induced oxidative stress. > There was a strong correlation between cytochrome P4501A activity and oxidative stress as measured with the comet assay. > There was no correlation between

ZnO/graphite composites and its antibacterial activity at different conditions.

PubMed

Dědková, Kateřina; Janíková, Barbora; Matějová, Kateřina; Čabanová, Kristina; Váňa, Rostislav; Kalup, Aleš; Hundáková, Marianna; Kukutschová, Jana

2015-10-01

The paper reports laboratory preparation, characterization and in vitro evaluation of antibacterial activity of ZnO/graphite nanocomposites. Zinc chloride and sodium carbonate served as precursors for synthesis of zinc oxide, while micromilled and natural graphite were used as the matrix for ZnO nanoparticles anchoring. During the reaction of ZnCl2 with saturated aqueous solution of Na2CO3a new compound is created. During the calcination at the temperature of 500 °C this new precursors decomposes and ZnO nanoparticles are formed. Composites ZnO/graphite with 50 wt.% of ZnO particles were prepared. X-ray powder diffraction and Raman microspectroscopy served as phase-analytical methods. Scanning electron microscopy technique was used for morphology characterization of the prepared samples and EDS mapping for visualization of elemental distribution. A developed modification of the standard microdilution test was used for in vitro evaluation of daylight induced antibacterial activity and antibacterial activity at dark conditions. Common human pathogens served as microorganism for antibacterial assay. Antibacterial activity of ZnO/graphite composites could be based on photocatalytic reaction; however there is a role of Zn(2+) ions on the resulting antibacterial activity which proved the experiments in dark condition. There is synergistic effect between Zn(2+) caused and reactive oxygen species caused antibacterial activity. Copyright © 2015 Elsevier B.V. All rights reserved.

Chemical manipulation of oxygen vacancy and antibacterial activity in ZnO.

PubMed

V, Lakshmi Prasanna; Vijayaraghavan, Rajagopalan

2017-08-01

Pure and doped ZnO (cation and anion doping) compositions have been designed in order to manipulate oxygen vacancy and antibacterial activity of ZnO. In this connection, we have synthesized and characterized micron sized ZnO, N doped micron sized ZnO, nano ZnO, nano Na and La doped ZnO. The intrinsic vacancies in pure ZnO and the vacancies created by N and Na doping in ZnO have been confirmed by X-ray Photoelectron Spectroscopy(XPS) and Photoluminiscence Spectroscopy(PL). Reactive oxygen species (ROS) such as hydroxyl radicals, superoxide radicals and H 2 O 2 responsible for antibacterial activity have been estimated by PL, UV-Vis spectroscopy and KMnO 4 titrations respectively. It was found that nano Na doped ZnO releases highest amount of ROS followed by nano ZnO, micron N doped ZnO while micron ZnO releases the least amount of ROS. The concentration of vacancies follows the same sequence. This illustrates directly the correlation between ROS and oxygen vacancy in well designed pure and doped ZnO. For the first time, material design in terms of cation doping and anion doping to tune oxygen vacancies has been carried out. Interaction energy (E g ), between the bacteria and nanoparticles has been calculated based on Extended Derjaguin-Landau-Verwey-Overbeek (EDLVO) theory and is correlated with antibacterial activity. Copyright © 2017 Elsevier B.V. All rights reserved.

Antibacterial activity of DLC films containing TiO2 nanoparticles.

PubMed

Marciano, F R; Lima-Oliveira, D A; Da-Silva, N S; Diniz, A V; Corat, E J; Trava-Airoldi, V J

2009-12-01

Diamond-like carbon (DLC) films have been the focus of extensive research in recent years due to their potential applications as surface coatings on biomedical devices. Titanium dioxide (TiO2) in the anatase crystalline form is a strong bactericidal agent when exposed to near-UV light. In this work we investigate the bactericidal activity of DLC films containing TiO2 nanoparticles. The films were grown on 316L stainless-steel substrates from a dispersion of TiO2 in hexane using plasma-enhanced chemical vapor deposition. The composition, bonding structure, surface energy, stress, and surface roughness of these films were also evaluated. The antibacterial tests were performed against Escherichia coli (E. coli) and the results were compared to the bacterial adhesion force to the studied surfaces. The presence of TiO2 in DLC bulk was confirmed by Raman spectroscopy. As TiO2 content increased, I(D)/I(G) ratio, hydrogen content, and roughness also increased; the films became more hydrophilic, with higher surface free energy and the interfacial energy of bacteria adhesion decreased. Experimental results show that TiO2 increased DLC bactericidal activity. Pure DLC films were thermodynamically unfavorable to bacterial adhesion. However, the chemical interaction between the E. coli and the studied films increased for the films with higher TiO2 concentration. As TiO2 bactericidal activity starts its action by oxidative damage to the bacteria wall, a decrease in the interfacial energy of bacteria adhesion causes an increase in the chemical interaction between E. coli and the films, which is an additional factor for the increasing bactericidal activity. From these results, DLC with TiO2 nanoparticles can be useful for producing coatings with antibacterial properties.

Toxic responses of cytochrome P450 sub-enzyme activities to heavy metals exposure in soil and correlation with their bioaccumulation in Eisenia fetida.

PubMed

Cao, Xiufeng; Bi, Ran; Song, Yufang

2017-10-01

The dose- and time- dependent responses of cytochrome P450 (CYP) sub-enzyme activities to heavy metals in soil, and the relationships between biomarker responses and metal bioaccumulation in Eisenia fetida were evaluated. Earthworms were exposed to soils spiked with increasing doses of Cd, Cu, Pb or Zn for 21 d. Results demonstrated that EROD and CYP3A4 activities responded significantly with increasing dose and exposure duration. EROD activity significantly (P < 0.05) correlated with CYP3A4 activity exposed to Pb and Cu. The earthworm metal burdens had significant correlation with the total metal concentrations in soil (P < 0.01). The bioaccumulation factor (BAF) decreased with the increasing metal concentration in soil. The order of metal bioavailability to E. fetida was Cd > Zn > Cu > Pb. CYP3A4 activity in Pb-exposed earthworms had a significant correlation with the accumulated metal (P < 0.05). Both EROD and CYP3A4 activities in Cu-exposed worms negatively correlated with BAF (P < 0.05). Based on Discriminant Analysis (DA), CYPs activities were sensitive biomarkers of heavy metals exposure, and we also concluded that different biomarkers with multiple durations could be conducted in the eco-toxicological diagnosis of soil pollution. Copyright © 2017 Elsevier Inc. All rights reserved.

Activity of influenza C virus O-acetylesterase with O-acetyl-containing compounds.

PubMed Central

Garcia-Sastre, A; Villar, E; Manuguerra, J C; Hannoun, C; Cabezas, J A

1991-01-01

Influenza C virus (strain C/Johannesburg/1/66) was grown, harvested, purified and used as source for the enzyme O-acetylesterase (N-acyl-O-acetylneuraminate O-acetylhydrolase; EC 3.1.1.53). This activity was studied and characterized with regard to some new substrates. The pH optimum of the enzyme is around 7.6, its stability at different pH values shows a result similar to that of the pH optimum, and its activity is well maintained in the pH range from 7.0 to 8.5 (all these tests were performed with 4-nitrophenyl acetate as substrate). Remarkable differences were found in the values of both Km and Vmax, with the synthetic substrates 4-nitrophenyl acetate, 2-nitrophenyl acetate, 4-methylumbelliferyl acetate, 1-naphthyl acetate and fluorescein diacetate. The use of 4-nitrophenyl acetate, 4-methylumbelliferyl acetate or 1-naphthyl acetate as substrate seems to be convenient for routine work, but it is better to carry out the measurements in parallel with those on bovine submandibular gland mucin (the latter is a natural and commercially available substrate). It was found that 4-acetoxybenzoic acid, as well as the methyl ester of 2-acetoxybenzoic acid, but not 2-acetoxybenzoic acid itself, are cleaved by this enzyme. Triacetin, di-O-acetyladenosine, tri-O-acetyladenosine, and di-O-acetyl-N-acetyladenosine phosphate, hitherto unreported as substrates for this viral esterase, are hydrolysed at different rates by this enzyme. We conclude that the O-acetylesterase from influenza C virus has a broad specificity towards both synthetic and natural non-sialic acid-containing substrates. Zn2+, Mn2+ and Pb2+ (as their chloride salts), N-acetylneuraminic acid, 4-methyl-umbelliferone and 2-acetoxybenzoic acid (acetylsalicylic acid) did not act as inhibitors. Images Fig. 1. PMID:1991039

C-O and O-H Bond Activation of Methanole by Lanthanum

NASA Astrophysics Data System (ADS)

Silva, Ruchira; Hewage, Dilrukshi; Yang, Dong-Sheng

2012-06-01

The interaction between methanol (CH_3OH) molecules and laser-vaporized La atoms resulted in the cleavage of C-O and O-H bonds and the formation of three major products, LaH_2O_2, LaCH_4O_2 and LaC_2H_6O_2, in a supersonic molecular beam. These products were identified by time-of-flight mass spectrometry, and their electronic spectra were obtained using mass-analyzed threshold ionization (MATI) spectroscopy. From the MATI spectra, adiabatic ionization energies of the three complexes were measured to be 40136 (5), 39366 (5) and 38685 (5) cm-1 for LaH_2O_2, LaCH_4O_2 and LaC_2H_6O_2, respectively. The ionization energies of these complexes decrease as the size of the coordinated organic fragments increases. The most active vibrational transitions of all three complexes were observed to be the M-O stretches in the ionic state. A metal-ligand bending mode with a frequency of 127 cm-1 was also observed for [LaH_2O_2]^+. However, the spectra of the other two complexes were less resolved, due to the existence of a large number of low frequency modes, which could be thermally excited even in the supersonic molecular beams, and of multiple rotational isomers formed by the free rotation of the methyl group in these systems. The electronic transitions responsible for the observed spectra were identified as ^1A_1 (C2v) ← ^2A_1 (C2v) for LaH_2O_2 and ^1A (C_1) ← ^2A (C_1) for LaCH_4O_2 and LaC_2H_6O_2.

ZnO nanostructures with different morphology for enhanced photocatalytic activity

NASA Astrophysics Data System (ADS)

Peter, I. John; Praveen, E.; Vignesh, G.; Nithiananthi, P.

2017-12-01

ZnO nanomaterials of different morphologies have been synthesized and the effect of morphology on Photocatalytic activity on natural dye has been investigated. Crystalline size and lattice strain of the synthesized particles are determined by XRD analysis and Williamson-Hall (W-H) method respectively. All other important physical parameters such as strain, stress and energy density values are also calculated using W-H analysis using different models such as uniform deformation model, uniform deformation stress model and uniform deformation energy density model. A shift in the peak of FTIR spectrum of ZnO is observed due to morphology effects. The SEM analysis reveals that the synthesized ZnO nanoparticles appear as flake, rod and dot. ZnO quantum dot exhibits higher photocatalytic activity comparing to the other morphologies. Larger surface area, high adsorption rate, large charge separation and the slow recombination of electrons/holes in ZnO dots establish dots as favorable morphology for good photocatalysis. Among the three, ZnO quantum dot shows three-times enhancement in the kinetic rate constants of photocatalysis. The results confirm that availability of specific (active) surface area, photocatalytic potential and quantum confinement of photo-induced carriers differ with morphology.

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.

Biomonitoring of Environmental Status and Trends (BEST) Program: Environmental Contaminants and their Effects on Fish in the Mississippi River Basin

USGS Publications Warehouse

Schmitt, Christopher J.

2002-01-01

We collected, examined, and analyzed 1378 fish of 22 species from 47 sites in the Mississippi River basin (MRB) during 1995 and from a reference site in 1996. The sampling sites in the MRB represented National Contaminant Biomonitoring Program (NCBP) stations situated at key points on major rivers and National Water- Quality Assessment Program (NAWQA) stations located on lower-order rivers and streams in the Eastern Iowa Basins (EIB) and Mississippi Embayment (MSE) Study Units. The reference site was the water supply system of the USGS-Leetown Science Center in rural Jefferson County, WV. Common carp (Cyprinus carpio; carp) and black basses (Micropterus spp.; bass), the targeted species, together represented 82% of the fish collected. Each fish was examined in the field for externally and internally visible gross lesions, selected organs were weighed to compute various ponderal and organo-somatic indices, and selected tissues and fluids were obtained and preserved for analysis of biomarkers. Fish health indicators included splenic macrophage aggregates, lysozyme activity, and hispathological analysis of liver, kidney, and other tissues. Reproductive biomarkers included analysis of plasma concentrations of vitellogenin (vtg) and the sex steroid hormones 17-estradiol (E2) and 11-ketotestosterone (11- kt); and the histological determination of percent oocyte atresia (in female fish) and gonadal stage. Hepatic ethoxyresorufin O-deethylase (EROD) activity was also measured. Composite samples of whole fish from each station were grouped by species and gender and analyzed for persistent organochlorine and elemental contaminants and for dioxin-like activity (TCDD-EQ) using the H4IIE rat hepatoma cell bioassay. Organochlorine and inorganic contaminant concentrations in fish were generally low relative to historical levels at most sites, but remained present at concentrations representing threats to piscivorous wildlife in some locations. Toxaphene and DDT (mostly as p

Distinct water activation on polar/non-polar facets of ZnO nanoparticles

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

Zhang, He; Sun, Junming; Liu, Changjun

2015-11-01

ZnO nanoparticles with differing dominant facets were prepared and characterized by a complimentary of techniques such as X-ray diffraction, electron microscopy, temperature programmed desorption of H2O, and Fourier transform infrared spectroscopy analysis of adsorbed D2O. For the first time, water interaction/activation is compared on ZnO polar and non-polar facets. We report that non-polar facets exhibit high activity in water activation, which favors reactions such as ketonization and steam reforming in which dissociated water is involved. The distinct water dissociation on ZnO non-polar facets could be related to its facile formation of oxygen vacancies under realistic reaction conditions.

Electrospinning Fabrication of SrTiO3 Nanofibers and Their Photocatalytic Activity

NASA Astrophysics Data System (ADS)

Xu, Lei; Zhao, Yiping; Wang, Wei; Liu, Hao; Wang, Rui

2018-06-01

SrTiO3 nanofibers were fabricated by an electrospinning process. The phase, microstructure and photocatalytic activity of the obtained SrTiO3 nanofibers were investigated. The XRD patterns and the SEM images suggest that SrTiO3 nanofibers with perovskite phase and rough surface have been fabricated in the current work. The SrTiO3 nanofibers show a high efficiency decomposition of RhB under ultraviolet light irradiation. The high photocatalytic activity of SrTiO3 nanofibers results from the large specific surface area. The large specific surface area provides more surface active sits and makes an easier charge carrier transport. On the basis of the photocatalytic performance of SrTiO3 nanofibers, the possible photocatalysis mechanism was proposed.

Ternary composite of TiO2 nanotubes/Ti plates modified by g-C3N4 and SnO2 with enhanced photocatalytic activity for enhancing antibacterial and photocatalytic activity.

PubMed

Faraji, Masoud; Mohaghegh, Neda; Abedini, Amir

2018-01-01

A series of g-C 3 N 4 -SnO 2 /TiO 2 nanotubes/Ti plates were fabricated via simple dipping of TiO 2 nanotubes/Ti in a solution containing SnCl 2 and g-C 3 N 4 nanosheets and finally annealing of the plates. Synthesized plates were characterized by various techniques. The SEM analysis revealed that the g-C 3 N 4 -SnO 2 nanosheets with high physical stability have been successfully deposited onto the surface of TiO 2 nanotubes/Ti plate. Photocatalytic activity was investigated using two probe chemical reactions: oxidative decomposition of acetic acid and oxidation of 2-propanol under irradiation. Antibacterial activities for Escherichia coli (E. coli) bacteria were also investigated in dark and under UV/Vis illuminations. Detailed characterization and results of photocatalytic and antibacterial activity tests revealed that semiconductor coupling significantly affected the photocatalyst properties synthesized and hence their photocatalytic and antibacterial activities. Modification of TiO 2 nanotubes/Ti plates with g-C 3 N 4 -SnO 2 deposits resulted in enhanced photocatalytic activities in both chemical and microbial systems. The g-C 3 N 4 -SnO 2 /TiO 2 nanotubes/Ti plate exhibited the highest photocatalytic and antibacterial activity, probably due to the heterojunction between g-C 3 N 4 -SnO 2 and TiO 2 nanotubes/Ti in the ternary composite plate and thus lower electron/hole recombination rate. Based on the obtained results, a photocatalytic and an antibacterial mechanism for the degradation of E. coli bacteria and chemical pollutants over g-C 3 N 4 -SnO 2 /TiO 2 nanotubes/Ti plate were proposed and discussed. Copyright © 2017 Elsevier B.V. All rights reserved.

Ionic liquid-assisted photochemical synthesis of ZnO/Ag2O heterostructures with enhanced visible light photocatalytic activity

NASA Astrophysics Data System (ADS)

Zhao, Shuo; Zhang, Yiwei; Zhou, Yuming; Zhang, Chao; Fang, Jiasheng; Sheng, Xiaoli

2017-07-01

ZnO/Ag2O heterostructures have been successfully fabricated using ionic liquids (ILs) as templates by a simple photochemical route. The influence of the type of ionic liquid and synthetic method on the morphology of ZnO, as well as the photocatalytic activity for the degradation of Rhodamine B (RhB), tetracycline (TC) and ciprofloxacin (CIP) under ultraviolet and visible light irradiation was studied. The samples were characterized by XRD, SEM, TEM, PL and UV-vis DRS. The results established that the type of ionic liquid and synthetic method played an important role in the growth of ZnO nanoparticles. And as-fabricated ZnO/Ag2O materials exhibited self-assembled flower-like architecture whose size was about 3 μm. Moreover, as-prepared ZnO/Ag2O exhibited the enhanced photocatalytic activity than ZnO sample, which may be due to the special structure, heterojunction, enhanced adsorption capability of dye, the improved separation rate of photogenerated electron-hole pairs. According to the results of radical trapping experiments, it can be found that •OH and h+ were the main active species for the photocatalytic degradation of RhB. It is valuable to develop this facile route preparing the highly dispersive flower-like ZnO/Ag2O materials, which can be beneficial for environmental protection.

Photocatalytic activity of binary metal oxide nanocomposites of CeO2/CdO nanospheres: Investigation of optical and antimicrobial activity.

PubMed

Magdalane, C Maria; Kaviyarasu, K; Vijaya, J Judith; Siddhardha, Busi; Jeyaraj, B

2016-10-01

We report the synthesis of high quality CeO2-CdO binary metal oxide nanocomposites were synthesized by a simple chemical precipitation and hydrothermal method. Cerium nitrate and cadmium nitrate were used as precursors. Composition, structure and morphology of the nanocomposites were analyzed by X-ray diffraction (XRD) and high resolution transmission electron microscopy (HRTEM). XRD pattern proves that the final product has cubic phase and the particle size diameter of the nanocomposites are 27nm, XRD results also indicated that the crystalline properties of the nanocomposite were improved without affecting the parent lattice, FESEM analysis indicates that the product is composed of spherical particles in clusters. The morphological and optical properties of CeO2-CdO nanosamples were characterized by HRTEM and DRS spectroscopy. The IR results showed high purity of products and indicated that the nanocomposites are made up of CeO2 and CdO bonds. Absorption spectra exhibited an upward shift in characteristic peaks caused by the addition of transition metal oxide, suggesting that crystallinity of both the metal oxide is improved due to specific doping level. TGA plots further confirmed the purity and stability of nanomaterials prepared. Hence the nanocomposite has cubic crystal lattice and form a homogeneous solid structure. From the result, Cd(2+) ions are embedded in the cubic crystal lattice of ceria. The growth rate increases which are ascribed to the cationic doping with a lower valence cation. Ce-Cd binary metal oxide nanocomposites showed antibacterial activity, it showed the better growth inhibition towards p.aeruginosa. Exploit of photodegradation and photocatalytic activity of large scale synthesis of CeO2-CdO binary metal oxide nanocomposites was reported. Copyright © 2016 Elsevier B.V. All rights reserved.

The preparation and photocatalytic activity of CdS/(Cal-Ta2O5-SiO2) composite photocatalyst under visible light

NASA Astrophysics Data System (ADS)

Li, Juxia

2018-02-01

CdS/(Cal-Ta2O5-SiO2) composite photocatalyst has been successfully fabricated via wet chemistry method. Ta2O5-SiO2 with multi-step Ta2O5 deposition on SiO2 has more Ta2O5 on SiO2 to ensure the active sites. Trough multi-step calcination, Ta2O5 can load on SiO2 with uniform and stable, which make it have high photocatalytic activity. The obtained samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), diffuse reflectance ultraviolet-visible spectroscopy (UV-vis) and photoluminescence spectroscopy (PL). Without any co-catalysts, the as-prepared CdS/(Cal-Ta2O5-SiO2) exhibited remarkable photocatalytic activity and recyclability both in the degradation of rhodamine B and in the hydrogen production from water splitting under visible light.

The influence of ZnO-SnO2 nanoparticles and activated carbon on the photocatalytic degradation of toluene using continuous flow mode.

PubMed

Rangkooy, Hossein Ali; Tanha, Fatemeh; Jaafarzadeh, Neamat; Mohammadbeigi, Abolfazl

2017-01-01

The present study examined the gas-phase photocatalytic degradation of toluene using ZnO-SnO 2 nanocomposite supported on activated carbon in a photocatalytic reactor. Toluene was selected as a model pollutant from volatile organic compounds to determine the pathway of photocatalytic degradation and the factors influencing this degradation. The ZnO-SnO 2 nanocomposite was synthesized through co-precipitation method in a ratio of 2:1 and then supported on activated carbon. The immobilization of ZnO-SnO 2 nanocomposite on activated carbon was determined by the surface area and scanning electron micrograph technique proposed by Brunauer, Emmett, and Teller. The laboratory findings showed that the highest efficiency was 40% for photocatalytic degradation of toluene. The results also indicated that ZnO-SnO 2 nano-oxides immobilization on activated carbon had a synergic effect on photocatalytic degradation of toluene. Use of a hybrid photocatalytic system (ZnO/SnO 2 nano coupled oxide) and application of absorbent (activated carbon) may be efficient and effective technique for refinement of toluene from air flow.

The influence of ZnO-SnO2 nanoparticles and activated carbon on the photocatalytic degradation of toluene using continuous flow mode

PubMed Central

Rangkooy, Hossein Ali; Tanha, Fatemeh; Jaafarzadeh, Neamat; Mohammadbeigi, Abolfazl

2017-01-01

The present study examined the gas-phase photocatalytic degradation of toluene using ZnO-SnO2 nanocomposite supported on activated carbon in a photocatalytic reactor. Toluene was selected as a model pollutant from volatile organic compounds to determine the pathway of photocatalytic degradation and the factors influencing this degradation. The ZnO-SnO2 nanocomposite was synthesized through co-precipitation method in a ratio of 2:1 and then supported on activated carbon. The immobilization of ZnO-SnO2 nanocomposite on activated carbon was determined by the surface area and scanning electron micrograph technique proposed by Brunauer, Emmett, and Teller. The laboratory findings showed that the highest efficiency was 40% for photocatalytic degradation of toluene. The results also indicated that ZnO-SnO2 nano-oxides immobilization on activated carbon had a synergic effect on photocatalytic degradation of toluene. Use of a hybrid photocatalytic system (ZnO/SnO2 nano coupled oxide) and application of absorbent (activated carbon) may be efficient and effective technique for refinement of toluene from air flow. PMID:29497487

O-sulfated bacterial polysaccharides with low anticoagulant activity inhibit metastasis.

PubMed

Borgenström, Marjut; Wärri, Anni; Hiilesvuo, Katri; Käkönen, Rami; Käkönen, Sanna; Nissinen, Liisa; Pihlavisto, Marjo; Marjamäki, Anne; Vlodavsky, Israel; Naggi, Annamaria; Torri, Giangiacomo; Casu, Benito; Veromaa, Timo; Salmivirta, Markku; Elenius, Klaus

2007-07-01

Heparin-like polysaccharides possess the capacity to inhibit cancer cell proliferation, angiogenesis, heparanase-mediated cancer cell invasion, and cancer cell adhesion to vascular endothelia via adhesion receptors, such as selectins. The clinical applicability of the antitumor effect of such polysaccharides, however, is compromised by their anticoagulant activity. We have compared the potential of chemically O-sulfated and N,O-sulfated bacterial polysaccharide (capsular polysaccharide from E. COLI K5 [K5PS]) species to inhibit metastasis of mouse B16-BL6 melanoma cells and human MDA-MB-231 breast cancer cells in two in vivo models. We demonstrate that in both settings, O-sulfated K5PS was a potent inhibitor of metastasis. Reducing the molecular weight of the polysaccharide, however, resulted in lower antimetastatic capacity. Furthermore, we show that O-sulfated K5PS efficiently inhibited the invasion of B16-BL6 cells through Matrigel and also inhibited the in vitro activity of heparanase. Moreover, treatment with O-sulfated K5PS lowered the ability of B16-BL6 cells to adhere to endothelial cells, intercellular adhesion molecule-1, and P-selectin, but not to E-selectin. Importantly, O-sulfated K5PSs were largely devoid of anticoagulant activity. These findings indicate that O-sulfated K5PS polysaccharide should be considered as a potential antimetastatic agent.

Synthesis, structural properties and catalytic activity of MgO-SnO2 nanocatalysts

NASA Astrophysics Data System (ADS)

Perveen, Hina; Farrukh, Muhammad Akhyar; Khaleeq-ur-Rahman, Muhammad; Munir, Badar; Tahir, Muhammad Ashraf

2015-01-01

Surfactant controlled synthesis of magnesium oxide-tin oxide (MgO-SnO2) nanocatalysts was carried out via the hydrothermal method. Concentration of sodium dodecyl sulfate (SDS) was varied while all other reaction conditions were kept constant same for this purpose. Furthermore, MgO-SnO2 nanocatalysts were also prepared by changing the precursor's concentration. These precursors are magnesium nitrate Mg(NO3)2 · 6H2O and tin chloride (SnCl4 · 5H2O). The influence of these reaction parameters on the sizes and morphology of the nanocatalysts were studied by using Fourier transform infrared (FTIR) spectroscopy, Scanning electron microscopy-Energy dispersive X-ray (SEM-EDX), Powder X-ray diffraction (XRD), Transmission electron microscopy and Thermo gravimetric analysis (TGA). The catalytic efficiency of MgO-SnO2 was checked against 2,4-dinitrophenylhydrazine (DNPH), which is an explosive compound. The nanocatalysts were found as a good catalyst to degrade the DNPH. Catalytic activity of nanocatalysts was observed up to 19.13% for the degradation DNPH by using UV-spectrophotometer.

Enhanced photoelectrochemical performance and photocatalytic activity of ZnO/TiO2 nanostructures fabricated by an electrostatically modified electrospinning

NASA Astrophysics Data System (ADS)

Ramos, Pierre G.; Flores, Edson; Sánchez, Luis A.; Candal, Roberto J.; Hojamberdiev, Mirabbos; Estrada, Walter; Rodriguez, Juan

2017-12-01

In this work, ZnO/TiO2 nanostructures were fabricated by an electrostatically modified electrospinning technique using zinc acetate and commercially available TiO2-P25, polyvinyl alcohol, and a solvent. The ZnO/TiO2 nanostructures were fabricated on fluorine-doped tin oxide (FTO) glass substrate by electrospinning of aqueous solution containing different amounts of zinc acetate. The TiO2-P25 nanoparticles were immobilized within zinc acetate/PVA nanofibers. The precursor nanofibers obtained were converted into polycrystalline ZnO and ZnO/TiO2 by calcination at 600 °C. The structure and morphology of the obtained nanostructures were characterized by X-ray diffraction and field emission scanning electron microscopy, respectively. It was found that the TiO2-P25 nanoparticles were attached to the ZnO nanostructures, and the mean diameter of the nanoparticles forming the nanostructures ranged from 31 to 52 nm with increasing the amount of zinc acetate. The incident photon-to-current efficiency (IPCE) spectra of the fabricated nanostructures were measured in a three-electrode cell. The photocatalytic activities of ZnO and ZnO/TiO2 nanostructures were evaluated toward the decomposition of methyl orange. The obtained results evidenced that the coupling of TiO2 with ZnO enhanced the IPCE and improved the photocatalytic activity of ZnO. Particularly, the ZnO/TiO2 nanostructures fabricated with a zinc acetate-to-PVA ratio of 2:3 exhibited the highest IPCE and photocatalytic activity.

Fabrication of Fe{sub 3}O{sub 4}@CuO core-shell from MOF based materials and its antibacterial activity

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

Rajabi, S.K.; Sohrabnezhad, Sh., E-mail: sohrabnezhad@guilan.ac.ir; Ghafourian, S.

Magnetic Fe{sub 3}O{sub 4}@CuO nanocomposite with a core/shell structure was successfully synthesized via direct calcinations of magnetic Fe{sub 3}O{sub 4}@HKUST-1 in air atmosphere. The morphology, structure, magnetic and porous properties of the as-synthesized nano composites were characterized by using scanning electron microscope (SEM), transmission electron microscopy (TEM), powder X-ray diffraction (PXRD), and vibration sample magnetometer (VSM). The results showed that the nanocomposite material included a Fe{sub 3}O{sub 4} core and a CuO shell. The Fe{sub 3}O{sub 4}@CuO core-shell can be separated easily from the medium by a small magnet. The antibacterial activity of Fe{sub 3}O{sub 4}-CuO core-shell was investigated againstmore » gram-positive and gram-negative bacteria. A new mechanism was proposed for inactivation of bacteria over the prepared sample. It was demonstrated that the core-shell exhibit recyclable antibacterial activity, acting as an ideal long-acting antibacterial agent. - Graphical abstract: Fe{sub 3}O{sub 4}@CuO core-shell release of copper ions. These Cu{sup 2+} ions were responsible for the exhibited antibacterial activity. - Highlights: • The Fe{sub 3}O{sub 4}@CuO core-shell was prepared by MOF method. • This is the first study of antibacterial activity of core-shell consist of CuO and Fe{sub 3}O{sub 4}. • The core-shell can be reused effectively. • Core-shell was separated from the reaction solution by external magnetic field.« less

Characterization of a heterobimetallic nonheme Fe(III)-O-Cr(III) species formed by O2 activation.

PubMed

Zhou, Ang; Kleespies, Scott T; Van Heuvelen, Katherine M; Que, Lawrence

2015-10-01

We report the generation and spectroscopic characterization of a heterobimetallic [(TMC)Fe(III)-O-Cr(III)(OTf)4] species (1) by bubbling O2 into a mixture of Fe(TMC)(OTf)2 and Cr(OTf)2 in NCCH3. Complex 1 also formed quantitatively by adding Cr(OTf)2 to [Fe(IV)(O)(TMC)(NCCH3)](2+). The proposed O2 activation mechanism involves the trapping of a Cr-O2 adduct by Fe(TMC)(OTf)2.

Characterization of a Heterobimetallic Nonheme Fe(III)-O-Cr(III) Species Formed by O2 Activation

PubMed Central

Zhou, Ang; Kleespies, Scott T.; Van Heuvelen, Katherine M.; Que, Lawrence

2015-01-01

We report the generation and spectroscopic characterization of a heterobimetallic [(TMC)FeIII-O-CrIII(OTf)4] species (1) by O2 bubbling into a mixture of Fe(TMC)(OTf)2 and Cr(OTf)2 in NCCH3. Complex 1 also formed quantitatively by adding Cr(OTf)2 to [FeIV(O)(TMC)(NCCH3)]2+. The proposed O2 activation mechanism involves the trapping by a Cr-O2 adduct by Fe(TMC)(OTf)2. PMID:26265081

Mesoporous Cu2O-CeO2 composite nanospheres with enhanced catalytic activity for 4-nitrophenol reduction

NASA Astrophysics Data System (ADS)

Pang, Juanjuan; Li, Wenting; Cao, Zhenhao; Xu, Jingjing; Li, Xue; Zhang, Xiaokai

2018-05-01

In this paper, mesoporous Cu2O-CeO2 nanospheres were fabricated via a facile, low-temperature solution route in the presence of poly(2-vinylpyridine)-b-poly(ethylene Oxide) (P2VP-b-PEO) block copolymers. The prepared mesoporous Cu2O-CeO2 nanospheres were characterized systematically by scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS) and nitrogen adsorption/desorption. The formation mechanism of mesoporous Cu2O-CeO2 nanospheres was discussed. The results show that the molar ratios of Ce3+/Cu2+ and the reaction time have an important influence on the nanostructure of Cu2O-CeO2 composite spheres. The resultant Cu2O-CeO2 nanospheres exhibit superior catalytic activities in the reduction of 4-nitrophenol to 4-aminophenol by NaBH4. The activity factor (K = k/m) for the Cu2O-CeO2 nanospheres prepared with the molar ratio of Ce3+/Cu2+ of 5/1 is 3006.6 s-1 g-1, which is much higher than reported values. This paper demonstrates a highly controllable approach to the production of mesoporous Cu2O-CeO2 nanospheres, which have potential applications in the areas of catalysis, adsorption, sensors and so on.

Antibacterial photocatalytic activity of different crystalline TiO2 phases in oral multispecies biofilm.

PubMed

Pantaroto, Heloisa N; Ricomini-Filho, Antonio P; Bertolini, Martinna M; Dias da Silva, José Humberto; Azevedo Neto, Nilton F; Sukotjo, Cortino; Rangel, Elidiane C; Barão, Valentim A R

2018-07-01

Titanium dioxide (TiO 2 ) incorporation in biomaterials is a promising technology due to its photocatalytic and antibacterial activities. However, the antibacterial potential of different TiO 2 crystalline structures on a multispecies oral biofilm remains unknown. We hypothesized that the different crystalline TiO 2 phases present different photocatalytic and antibacterial activities. Three crystalline TiO 2 films were deposited by magnetron sputtering on commercially pure titanium (cpTi), in order to obtain four groups: (1) machined cpTi (control); (2) A-TiO 2 (anatase); (3) M-TiO 2 (mixture of anatase and rutile); (4) R-TiO 2 (rutile). The morphology, crystalline phase, chemical composition, hardness, elastic modulus and surface free energy of the surfaces were evaluated. The photocatalytic potential was assessed by methylene blue degradation assay. The antibacterial activity was evaluated on relevant oral bacteria, by using a multispecies biofilm (Streptococcus sanguinis, Actinomyces naeslundii and Fusobacterium nucleatum) formed on the treated titanium surfaces (16.5h) followed by UV-A light exposure (1h) to generate reactive oxygen species production. All TiO 2 films presented around 300nm thickness and improved the hardness and elastic modulus of cpTi surfaces (p<0.05). A-TiO 2 and M-TiO 2 films presented superior photocatalytic activity than R-TiO 2 (p<0.05). M-TiO 2 revealed the greatest antibacterial activity followed by A-TiO 2 (≈99.9% and 99% of bacterial reduction, respectively) (p<0.001 vs. control). R-TiO 2 had no antibacterial activity (p>0.05 vs. control). This study brings new insights on the development of extra oral protocols for the photocatalytic activity of TiO 2 in oral biofilm-associated disease. Anatase and mixture-TiO 2 showed antibacterial activity on this oral bacterial biofilm, being promising surface coatings for dental implant components. Copyright © 2018 The Academy of Dental Materials. All rights reserved.

A Classroom Activity: Tracking El Niño

ERIC Educational Resources Information Center

Ribbe, Joachim

2016-01-01

This paper aims to introduce an activity for teachers to assist in meeting learning outcomes as defined in the earth and environmental science units of the Australian Curriculum. The focus of the classroom tasks is on a global ocean feature referred to as El Niño. This phenomenon is part of the El Niño Southern Oscillation, which is largely…

Fabrication of Fe3O4@CuO core-shell from MOF based materials and its antibacterial activity

NASA Astrophysics Data System (ADS)

Rajabi, S. K.; Sohrabnezhad, Sh.; Ghafourian, S.

2016-12-01

Magnetic Fe3O4@CuO nanocomposite with a core/shell structure was successfully synthesized via direct calcinations of magnetic Fe3O4@HKUST-1 in air atmosphere. The morphology, structure, magnetic and porous properties of the as-synthesized nano composites were characterized by using scanning electron microscope (SEM), transmission electron microscopy (TEM), powder X-ray diffraction (PXRD), and vibration sample magnetometer (VSM). The results showed that the nanocomposite material included a Fe3O4 core and a CuO shell. The Fe3O4@CuO core-shell can be separated easily from the medium by a small magnet. The antibacterial activity of Fe3O4-CuO core-shell was investigated against gram-positive and gram-negative bacteria. A new mechanism was proposed for inactivation of bacteria over the prepared sample. It was demonstrated that the core-shell exhibit recyclable antibacterial activity, acting as an ideal long-acting antibacterial agent.

Precision-Cut Liver Slices of Salmo salar as a tool to investigate the oxidative impact of CYP1A-mediated PCB 126 and 3-methylcholanthrene metabolism.

PubMed

Lemaire, Benjamin; Beck, Michaël; Jaspart, Mélanie; Debier, Cathy; Calderon, Pedro Buc; Thomé, Jean-Pierre; Rees, Jean-François

2011-02-01

Fish isolated cell systems have long been used to predict in vivo toxicity of man-made chemicals. In present study, we tested the suitability of Precision-Cut Liver Slices (PCLS) as an alternative to these models that allows the evaluation of a global tissue response to toxicants, to investigate oxidative stress response to cytochrome P450 1A (CYP1A) induction in fish liver. PCLS of Salmo salar were exposed for 21 h to increasing doses of 3-methylcholanthrene (3-MC) and Polychlorobiphenyl 126 (PCB 126). 3-MC (25 μM) strongly induced CYP1A transcription. In dose-response analysis (25-100 μM), EROD activity was strongly increased at intermediate 3-MC concentrations. We found the counter-intuitive decline of EROD at the highest 3-MC doses to result from reversible competition with ethoxyresorufin. No increases of H(2)O(2) production, antioxidant enzymes activities or oxidative damage to lipids were found with 3-MC treatments. PCLS subjected to PCB 126 (2-200 nM) showed increased contamination levels and a parallel increased CYP1A mRNA synthesis and EROD activity. H(2)O(2) production tended to increase but no oxidative damage to lipids was found. As antioxidant enzymes activities declined at the highest PCB 126 dose, it is suggested that longer incubation periods could be required to generate oxidative stress in PCLS. Copyright © 2010 Elsevier Ltd. All rights reserved.

Increased photocatalytic activity induced by TiO2/Pt/SnO2 heterostructured films

NASA Astrophysics Data System (ADS)

Testoni, Glaucio O.; Amoresi, Rafael A. C.; Lustosa, Glauco M. M. M.; Costa, João P. C.; Nogueira, Marcelo V.; Ruiz, Miguel; Zaghete, Maria A.; Perazolli, Leinig A.

2018-02-01

In this work, a high photocatalytic activity was attained by intercalating a Pt layer between SnO2 and TiO2 semiconductors, which yielded a TiO2/Pt/SnO2 - type heterostructure used in the discoloration of blue methylene (MB) solution. The porous films and platinum layer were obtained by electrophoretic deposition and DC Sputtering, respectively, and were both characterized morphologically and structurally by FE-SEM and XRD. The films with the Pt interlayer were evaluated by photocatalytic activity through exposure to UV light. An increase in efficiency of 22% was obtained for these films compared to those without platinum deposition. Studies on the reutilization of the films pointed out high efficiency and recovery of the photocatalyst, rendering the methodology favorable for the construction of fixed bed photocatalytic reactors. A proposal associated with the mechanism is discussed in this work in terms of the difference in Schottky barrier between the semiconductors and the electrons transfer and trapping cycle. These are fundamental factors for boosting photocatalytic efficiency.

Short-term effects of TiO2, CeO2, and ZnO nanoparticles on metabolic activities and gene expression of Nitrosomonas europaea.

PubMed

Yu, Ran; Fang, Xiaohua; Somasundaran, Ponisseril; Chandran, Kartik

2015-06-01

Nanosized TiO2 (n-TiO2), CeO2 (n-CeO2), and ZnO (n-ZnO) and bulk ZnO were chosen for a 4-h exposure study on a model ammonia oxidizing bacterium, Nitrosomonas europaea. n-ZnO displayed the most serious cytotoxicity while n-TiO2 was the least toxic one. The change of cell morphologies, the retardance of specific oxygen uptake rates and ammonia oxidation rates, and the depression of amoA gene expressions under NP stresses were generally observed when the cell densities and membrane integrities were not significantly impaired yet. The TEM imaging and the synchrotron X-ray fluorescence microscopy of the NPs impacted cells revealed the increase of the corresponding intracellular Ti, Ce or Zn contents and suggested the intracellular NP accumulation. The elevation of intracellular S contents accompanied with higher K contents implied the possible activation of thiol-containing glutathione and thioredoxin production for NP stress alleviation. The NP cytotoxicity was not always a function of NP concentration. The 200 mg L(-1) n-TiO2 or n-CeO2 impacted cells displayed the similar ammonia oxidation activities but higher amoA gene expression levels than the 20 mg L(-1) NPs impacted ones. Such phenomenon further indicated the possible establishment of an anti-toxicity mechanism in N. europaea at the genetic level to redeem the weakened AMO activities along with the NP aggregation effects. Copyright © 2015 Elsevier Ltd. All rights reserved.

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

Transition Metal Ions in Zeolites: Coordination and activation of O2

PubMed Central

Smeets, Pieter J.; Woertink, Julia S.; Sels, Bert F.; Solomon, Edward I.; Schoonheydt, Robert A.

2010-01-01

Zeolites containing transition metal ions (TMI) often show promising activity as heterogeneous catalysts in pollution abatement and selective oxidation reactions. In this paper, two aspects of research on the TMI Cu, Co and Fe in zeolites are discussed: (i) coordination to the lattice and (ii) activated oxygen species. At low loading, TMI preferably occupy exchange sites in six-membered oxygen rings (6MR) where the TMI preferentially coordinate with the oxygen atoms of Al tetrahedra. High TMI loadings result in a variety of TMI species formed at the zeolite surface. Removal of the extra-lattice oxygens during high temperature pretreatments can result in auto-reduction. Oxidation of reduced TMI sites often results in the formation of highly reactive oxygen species. In Cu-ZSM-5, calcination with O2 results in the formation of a species, which was found to be a crucial intermediate in both the direct decomposition of NO and N2O and the selective oxidation of methane into methanol. An activated oxygen species, called α-oxygen, is formed in Fe-ZSM5 and reported to be the active site in the partial oxidation of methane and benzene into methanol and phenol, respectively. However, this reactive α-oxygen can only be formed with N2O, not with O2. O2 activated Co intermediates in Faujasite (FAU) zeolites can selectively oxidize α-pinene and epoxidize styrene. In Co-FAU, CoIII superoxo and peroxo complexes are suggested to be the active cores, whereas in Cu and Fe-ZSM-5 various monomeric and dimeric sites have been proposed, but no consensus has been obtained. Very recently, the active site in Cu-ZSM-5 was identified as a bent [Cu-O-Cu]2+ core (Proc. Natl. Acad. Sci. USA 2009, 106, 18908-18913). Overall, O2 activation depends on the interplay of structural factors such as type of zeolite, size of the channels and cages and chemical factors such as Si/Al ratio and the nature, charge and distribution of the charge balancing cations. The presence of several different TMI sites