Bioremediation of PAHs - Limitations and soultions

Introduction 1.1 Occurrence of polycyclic aromatic hydrocarbons (PAH) in the environment Worldwide industrial and agricultural developments have released a large number of natural and synthetic hazardous compounds into the environment due to careless waste disposal, illegal waste dumping and accidental spills. As a result, there are numerous sites in the world that require cleanup of soils and groundwater. Polycyclic aromatic hydrocarbons (PAHs) are one of the major groups of these contaminants (Da Silva et al., 2003). PAHs constitute a diverse class of organic compounds consisting of two or more aromatic rings with various structural configurations (Prabhu and Phale, 2003). Being a derivative of benzene, PAHs are thermodynamically stable. In addition, these chemicals tend to adhere to particle surfaces, such as soils, because of their low water solubility and strong hydrophobicity, and this results in greater persistence under natural conditions. This persistence coupled with their potential carcinogenicity makes PAHs problematic environmental contaminants (Cerniglia, 1992; Sutherland, 1992). PAHs are widely found in high concentrations at many industrial sites, particularly those associated with petroleum, gas production and wood preserving industries (Wilson and Jones, 1993). 1.2 Remediation technologies Conventional techniques used for the remediation of soil polluted with organic contaminants include excavation of the contaminated soil and disposal to a landfill or capping - containment - of the contaminated areas of a site. These methods have some drawbacks. The first method simply moves the contamination elsewhere and may create significant risks in the excavation, handling and transport of hazardous material. Additionally, it is very difficult and increasingly expensive to find new landfill sites for the final disposal of the material. The cap and containment method is only an interim solution since the contamination remains on site, requiring monitoring and maintenance of the isolation barriers long into the future, with all the associated costs and potential liability. A better approach than these traditional methods is to completely destroy the pollutants, if possible, or transform them into harmless substances. Some technologies that have been used are high-temperature incineration and various types of chemical decomposition (for example, base-catalyzed dechlorination, UV oxidation). However, these methods have significant disadvantages, principally their technological complexity, high cost , and the lack of public acceptance. Bioremediation, on the contrast, is a promising option for the complete removal and destruction of contaminants. 1.3 Bioremediation of PAH contaminated soil & groundwater Bioremediation is the use of living organisms, primarily microorganisms, to degrade or detoxify hazardous wastes into harmless substances such as carbon dioxide, water and cell biomass Most PAHs are biodegradable unter natural conditions (Da Silva et al., 2003; Meysami and Baheri, 2003) and bioremediation for cleanup of PAH wastes has been extensively studied at both laboratory and commercial levels- It has been implemented at a number of contaminated sites, including the cleanup of the Exxon Valdez oil spill in Prince William Sound, Alaska in 1989, the Mega Borg spill off the Texas coast in 1990 and the Burgan Oil Field, Kuwait in 1994 (Purwaningsih, 2002). Different strategies for PAH bioremediation, such as in situ , ex situ or on site bioremediation were developed in recent years. In situ bioremediation is a technique that is applied to soil and groundwater at the site without removing the contaminated soil or groundwater, based on the provision of optimum conditions for microbiological contaminant breakdown.. Ex situ bioremediation of PAHs, on the other hand, is a technique applied to soil and groundwater which has been removed from the site via excavation (soil) or pumping (water). Hazardous contaminants are converted in controlled bioreactors into harmless compounds in an efficient manner. 1.4 Bioavailability of PAH in the subsurface Frequently, PAH contamination in the environment is occurs as contaminants that are sorbed onto soilparticles rather than in phase (NAPL, non aqueous phase liquids). It is known that the biodegradation rate of most PAHs sorbed onto soil is far lower than rates measured in solution cultures of microorganisms with pure solid pollutants (Alexander and Scow, 1989; Hamaker, 1972). It is generally believed that only that fraction of PAHs dissolved in the solution can be metabolized by microorganisms in soil. The amount of contaminant that can be readily taken up and degraded by microorganisms is defined as bioavailability (Bosma et al., 1997; Maier, 2000). Two phenomena have been suggested to cause the low bioavailability of PAHs in soil (Danielsson, 2000). The first one is strong adsorption of the contaminants to the soil constituents which then leads to very slow release rates of contaminants to the aqueous phase. Sorption is often well correlated with soil organic matter content (Means, 1980) and significantly reduces biodegradation (Manilal and Alexander, 1991). The second phenomenon is slow mass transfer of pollutants, such as pore diffusion in the soil aggregates or diffusion in the organic matter in the soil. The complex set of these physical, chemical and biological processes is schematically illustrated in Figure 1. As shown in Figure 1, biodegradation processes are taking place in the soil solution while diffusion processes occur in the narrow pores in and between soil aggregates (Danielsson, 2000). Seemingly contradictory studies can be found in the literature that indicate the rate and final extent of metabolism may be either lower or higher for sorbed PAHs by soil than those for pure PAHs (Van Loosdrecht et al., 1990). These contrasting results demonstrate that the bioavailability of organic contaminants sorbed onto soil is far from being well understood. Besides bioavailability, there are several other factors influencing the rate and extent of biodegradation of PAHs in soil including microbial population characteristics, physical and chemical properties of PAHs and environmental factors (temperature, moisture, pH, degree of contamination). Figure 1: Schematic diagram showing possible rate-limiting processes during bioremediation of hydrophobic organic contaminants in a contaminated soil-water system (not to scale) (Danielsson, 2000). 1.5 Increasing the bioavailability of PAH in soil Attempts to improve the biodegradation of PAHs in soil by increasing their bioavailability include the use of surfactants , solvents or solubility enhancers.. However, introduction of synthetic surfactant may result in the addition of one more pollutant. (Wang and Brusseau, 1993).A study conducted by Mulder et al. showed that the introduction of hydropropyl-ß-cyclodextrin (HPCD), a well-known PAH solubility enhancer, significantly increased the solubilization of PAHs although it did not improve the biodegradation rate of PAHs (Mulder et al., 1998), indicating that further research is required in order to develop a feasible and efficient remediation method. Enhancing the extent of PAHs mass transfer from the soil phase to the liquid might prove an efficient and environmentally low-risk alternative way of addressing the problem of slow PAH biodegradation in soil.

Variable Na(v)1.5 protein expression from the wild-type allele correlates with the penetrance of cardiac conduction disease in the Scn5a(+/-) mouse model

BACKGROUND: Loss-of-function mutations in SCN5A, the gene encoding Na(v)1.5 Na+ channel, are associated with inherited cardiac conduction defects and Brugada syndrome, which both exhibit variable phenotypic penetrance of conduction defects. We investigated the mechanisms of this heterogeneity in a mouse model with heterozygous targeted disruption of Scn5a (Scn5a(+/-) mice) and compared our results to those obtained in patients with loss-of-function mutations in SCN5A. METHODOLOGY/PRINCIPAL FINDINGS: Based on ECG, 10-week-old Scn5a(+/-) mice were divided into 2 subgroups, one displaying severe ventricular conduction defects (QRS interval>18 ms) and one a mild phenotype (QRS< or = 18 ms; QRS in wild-type littermates: 10-18 ms). Phenotypic difference persisted with aging. At 10 weeks, the Na+ channel blocker ajmaline prolonged QRS interval similarly in both groups of Scn5a(+/-) mice. In contrast, in old mice (>53 weeks), ajmaline effect was larger in the severely affected subgroup. These data matched the clinical observations on patients with SCN5A loss-of-function mutations with either severe or mild conduction defects. Ventricular tachycardia developed in 5/10 old severely affected Scn5a(+/-) mice but not in mildly affected ones. Correspondingly, symptomatic SCN5A-mutated Brugada patients had more severe conduction defects than asymptomatic patients. Old severely affected Scn5a(+/-) mice but not mildly affected ones showed extensive cardiac fibrosis. Mildly affected Scn5a(+/-) mice had similar Na(v)1.5 mRNA but higher Na(v)1.5 protein expression, and moderately larger I(Na) current than severely affected Scn5a(+/-) mice. As a consequence, action potential upstroke velocity was more decreased in severely affected Scn5a(+/-) mice than in mildly affected ones. CONCLUSIONS: Scn5a(+/-) mice show similar phenotypic heterogeneity as SCN5A-mutated patients. In Scn5a(+/-) mice, phenotype severity correlates with wild-type Na(v)1.5 protein expression.

The Amplifier - v. 2, no. 11

In this issue...State Board of Education, Helen Allen, Drama Club, Galen Hospital, Lydia's, Butte, Montana, convocation, Marion White Arts Society, Professor William W. Chance

The Amplifier - v. 4, no. 3

In this issue...Geology, Sidney L. Groff, Mineral Collection, cheerleaders, Ski Club, Library, Newman Club, Ed Simonich, Butte Jaycees, Youth Center

The Amplifier - v. 5, no. 8

In this issue...Koehler S. Stout, Spanish, The Anaconda Company, William A. Clark, Butte Chamber of Commerce, Pennsylvania Mine, Glee Club, Metal's Bank, March of Dimes

The Amplifier - v. 6, no. 2

In this issue...Stanley Bosch, homecoming, Naranche Stadium, NROTC, Petroleum Engineering, Magma annual, Platter Chatter, Masonic ballroom, International Club, Kelley Hemmert

The Amplifier - v. 6, no. 11

In this issue...April Fool edition, seismograpgh, Petroleum Engineer, Library display, Anson Ford, Butte postmaster, Dr. Vernon Griffiths, Alumni tickets, ping pong, Magma

Warum Pentose- und nicht Hexose-Nucleinsäuren??. Teil V. (Purin-Purin)-Basenpaarung in der homo-DNS-Reihe: Guanin, Isoguanin, 2,6-Diaminopurin und Xanthin

Why Pentose- and Not Hexose-Nucleic Acids? Purine-Purine Pairing in homo-DNA: Guanine,Isoguanine, 2,6-Diaminopurine, and Xanthine This paper concludes the series of reports in this journal [1–4] on the chemistry of homo-DNA, the constitutionally simplifie dmodel system of hexopyranosyl-(6′ → 4′)-oligonucleotide systems stidued in our laboratory as potentially natural-nucleic-acid alternatives in the context of a chemical aetiology of nucleic-acid structure. The report describes the synthesis and pairing properties of homo-DNA oligonucleotides which contain as nucleobases exclusively purines, and gives, together with part III of the series [3], a survey of what we know today about purine-purine pairingin homo-DNA. In addition, the paper discusses those aspects of the chemistry of homo-DNA which, we think, influence the way how some of the structural features of DNA (and RNA) are to be interpreted on a qualitative level. Purine-purine pairing occurs in the homo-DNA domain in great variety. Most prominent is a novel tridentate Watson-Crick pair between guanine and isoguanine, as well as one between 2,6-diaminopurine and xanthinone, both giving rise to very stable duplexes containing the all-purine strands in antiparallel orientation. For the guanine-isoguanine pair, constitutional assignment is based on temperature-dependent UV and CD spectroscopy of various guanine- and isoguanine-containg duplexes in comparison with duplexes known to be paired in the reverse guanine is replaced by 7-carbauguanine. Isoguanine and 2,6-diaminopurine also have the capability of self-pariring in the reverse-Hoogsteen mode, as previously observed for adenine and guanine [3]. In this type of pairing, the interchangeably. Fig. 36 provides an overall survey of the relative strength of pairing in all possible purine-purine combinations. Watson-Crick pairing of isoguanine with guanine demands the former to participate in its 3H-tautomeric form; hitherto this specific tautomer had not been considered in the pairing chemistry of isoguanine. Whereas (cumulative) purine-purine pairing in DNA (reverse-Hoogsten or Hoogsteen) seems to occur in triplexes and tetrapalexes only, its occurrence in duplexes in a characteristic feature of homo-DNA chemistry. The occurrence of purine-purine Watson-Crick base pairs is probably a consequence of homo-DNA's quasi-linear ladder structure [1][4]. In a double helix, the distance between the two sugar C-atoms, on which a base pair is anchored, is expected to be constrained by the dimensions of the helix; in a linear duplex, however, there would be no restrictions with regard to base-pair length. Homo-DNA's ladder-like model also allows one to recognize one of the reasons why nucleic-acid duplexes prefer to pair in antiparallel, rather than parallel strand orientation: in homo-DNA duplexes, (averaged) backbone and base pair axes are strongly inclined toward one another [4]; the stronger this inclination, the higher the preference for antiparallel strand orientation is expected to be (Fig. 16). In retrospect, homo-DNA turns out to be one of the first artificial oligonucleotide systems (cf. Footnote 65) to demonstrate in a comprehensive way that informational base pairing involving purines and pyrimidines is not a capability unique to ribofuranosyl systems. Stability and helical shape of pairing complexes are not necessary conditions of one another; it is the potential for extensive conformational cooperativity of hte backbone structure with respect to the constellational demands of base pairing and base stacking that determines whether or nor a given type of base-carrying backbone structure is an informational pairing system. From the viewpoint of the chemical aetiology of nucleic-acid structure, which inspired our investigations on hexopyranosyl-(6′ → 4′)-oligonucleotide systems in the first place, the work on homo-DNA is only an extensive model study, because homo-DNA is not to be considered a potential natural-nucleic-acid altenratie. In retrospect, it seems fortunate that the model study was carried out, because without it we could hardly have comprehended the pairing behavior of the proper nucleic-acid alternatives which we have studied later and which will be discussed in Part VI of this series. The English footnotes to Fig. 1–49 provide an extension of this summary.

Na 1 Nachlass Max Horkheimer, 447 - Korrespondenzen mit der UNESCO (p. V 169, 1-164)

UNESCO: Drucksachen und Schriftwechsel, 1957-1965; 4 Briefe mit Beilagen zwischen Prof. Georg Eckert und Max Horkheimer, 1967; 9 Briefe mit Beilagen zwischen R. William Jones (UNESCO) und Max Horkheimer, 1964-1965;

Na 1 Nachlass Max Horkheimer, 493 - Korrespondenzen mit Mitarbeitern (u.a. Gerhard Brand, Ludwig von Friedeburg und Jürgen Habermas) aus dem Institut für Sozialforschung (p. V 193, 1 - 212)

Briefe zwischen Mitarbeitern des Instituts für Sozialforschung und Max Horkheimer, 1964-1973; 13 Briefe und Beilagen zwischen dem Verwaltungsleiter IfS Siegfried Geissler und Max Horkheimer, 1968-1973; 9 Briefe zwischen Klaus Körber (Institut für Sozialforschung) und Max Horkheimer, 1971-1973; 2 Briefe zwischen dem Professor Rudolf Gunzert und Max Horkheimer, 1972; 2 Briefe zwischen Dr. Joachim Bergmann (Institut für Sozialforschung) und Max Horkheimer, 1971; 2 Briefe zwischen dem Professor Gerhard Brandt und Max Horkheimer, 1971; 6 Briefe zwischen Herbert Ludwig (Institut für Sozialforschung) und Max Horkheimer, 1966-1967; 3 Briefe von Max Horkheimer an Professor Franz Böhm, 1966; Briefe zwischen den Mitarbeitern des Instituts für Sozialforschung und Max Horkheimer, 1955-1959; 4 Briefe von Jürgen Habermas an Max Horkheimer, Frankfurt, 1957-1959; 3 Briefe zwischen Christoph Oehler und Max Horkheimer, 1959; 13 Briefe zwischen Ludwig von Friedeburg und Max Horkheimer, 1955-1959; 1 Brief von Werner Wilkening an Max Horkheimer, 1958; 1 Brief von Gerhard Brandt an Max Horkheimer, 1958; 1 Brief von Max Horkheimer an den Dekan Helmut Viebrock, 1958; 2 Briefe von Egon Becker mit Helge Pross und Ludwig Friedeburg an Max Horkheimer, Frankfurt, 1958-1959; 2 Briefe von Helge Pross mit Egon Becker und Ludwig Friedeburg an Max Horkheimer, Frankfurt, 1958-1959; 1 Brief von Dieter Arenz an Max Horkheimer, Frankfurt, 1956; Briefe vom und an das Institut für Sozialforschung (Advisory Board of the Institute of Social Research), 1940-1947; Briefe und Briefentwürfe an und von Mitgliedern des Advisory Board betreffend die Zusendung von Max Horkheimer "Eclipse of Reason" und Karl August Wittvogel/Olga Lang, "Chinese Family and Society"; vom Institut für Sozialforschung, 1946-1947; 1 Brief von Edwin Borchard vom Institut für Sozialforschung, 1947; 1 Brief von Friedrich Pollock an Alfred E. Cohn, Los Angeles, 1947; 1 Brief von Friedrich Pollock an Stephan Duggan, Los Angeles, 1947; 2 Briefe zwischen Lloyd K. Garrison und Friedrich. Pollock, 1947; 1 Brief von Friedrich Pollock an Calvin B. Hoover, Los Angeles, 1947; 1 Brief von Friedrich Pollock an Philip C. Jessup, Los Angeles, 1947; 1 Brief von Friedrich Pollock an Wesley C. Mitchell, Los Angeles, 1947; 1 Brief von Friedrich Pollock an William A. Neilson, Los Angeles, 1947; 1 Brief von Friedrich Pollock an Frederick M. Padelford, Los Angeles, 1947; 1 Brief von Friedrich Pollock an Thorsten Sellin, Los Angeles, 1947; 3 Briefe zwischen John Whyte und Friedrich Pollock, 1947; 2 Briefe zwischen Louis Wirth und Friedrich Pollock, 1947; 1 Brief von Friedrich Pollock an Howard Woolston, Los Angeles, 1947; 1 Brief von George H. Sabine an das Institut für Sozialforschung, Ithaca, New York, 1946; Briefe und Briefentwürfe an und von Mitgliedern des Advisory Board betreffend den Druck eines neuen Briefkopfs des Instituts, 1940; 1 Brief von Leo Löwenthal, Pacific Palisades an Margot von Mendelssohn, 1942; 1 Brief von Leo Löwenthal an Margot von Mendelssohn, Pacific Palisades, 1942; 1 Brief von Max Horkheimer an K. Pilser, 1942; 2 Briefe zwischen Charles A. Beard und Max Horkheimer, 1940; 2 Briefe zwischen Edwin M. Borchard und Max Horkheimer, 1940; 3 Briefe zwischen Henry Sloane Coffin und Max Horkheimer, 1940; 2 Briefe zwischen Morris R. Cohen und Max Horkheimer, 1940; 2 Briefe zwischen Alfred E. Cohn und Max Horkheimer, 1940; 2 Briefe zwischen Stephen Duggan und Max Horkheimer, 1940; 2 Briefe zwischen dem Soziologen Henry Pratt Fairchild und Max Horkheimer, 1940; 2 Briefe zwischen Sidney B. Fay und Max Horkheimer, 1940; 2 Briefe zwischen Lloyd K. Garrison und Max Horkheimer, 1940; 1 Brief von Max Horkheimer an Calvin B. Hoover, 1940; 2 Briefe zwischen Robert M. Hutchins und Max Horkheimer, 1940; 2 Briefe zwischen Philip C. Jessup und Max Horkheimer, 1940; 2 Briefe zwischen Lewis L. Lorwin und Max Horkheimer, 1940; 2 Briefe zwischen Robert S. Lynd und Max Horkheimer, 1940; 2 Briefe zwischen Robert M. MacIver und Max Horkheimer, 1940; 2 Briefe von Max Horkheimer an Charles H. McIlwain, 1940; 2 Briefe zwischen Charles E. Merriam und Max Horkheimer, 1940; 2 Briefe zwischen Wesley C. Mitchell und Max Horkheimer, 1940; 2 Briefe zwischen William A. Nielson und Max Horkheimer, 1940; 5 Briefe zwischen Howard W. Odum und Max Horkheimer, 1940; 3 Briefe zwischen Frederick M. Padelford und Max Horkheimer, 1940; 3 Briefe von Max Horkheimer an Max Radin, 1940; 2 Briefe zwischen George H. Sabine und Max Horkheimer, 1940; 2 Briefe zwischen Thorsten Sellin und Max Horkheimer, 1940; 2 Briefe zwischen James T. Shotwell und Max Horkheimer, 1940; 1 Brief von dem Soziologen Louis Wirth an Franz Neumann, Chicago, 1940; 1 Brief von Louis Wirth an Franz L. Neumann, Chicago, 1940; 3 Briefe zwischen Howard Woolston und Max Horkheimer, 1940;

Evrejskija narodnyja p-sni v Rossii

sobrany i izd. pod red. i s vvedeniem S.M. Ginzburga i P. S. Mareka

Description and chemical composition of ferromanganese encrustations and deposits in the Atlantic Ocean from R/V Atlantis II cruises 20, 42, 60, 85; R/V Chain cruise 35; R/V Knorr cruise 61 and RRS Shackleton cruise 75/1 stations

Chemical and mineralogical compositions of ferromanganese oxide coatings on rocks dredged from the New England Seamounts, the Sierra Leone Rise and the Mid-Atlantic Ridge near the Equator have been determined in an investigation of regional differences in Atlantic ferromanganese deposits. Most encrustations are clearly of hydrogenous origin, consisting mainly of todorokite and delta MnO2, but several recovered from the equatorial fracture zones may be hydrothermal accumulations. Differences in the chemistry of the water column and in growth rates of the ferromanganese coatings may be important in producing this regional contrast in composition. Fine-scale changes in element abundances within the encrustations indicate that the nature of the substrate has little influence on compositional variations.

Manganese nodules recovered by R/V Vityaz expedition

Uranium, radium, thorium and ionium were determined directly on seven concretions from three stations in the Indian Ocean, and on two concretions and a manganese-rich crust from two stations in the Pacific Ocean. The uranium content averages 3 to 5 gamma/g and the thorium content varies only slightly, but the Th/U ratio in the concretions is typically 2 to 5 in the Indian Ocean and 5 to 15.5 in the Pacific. The ionium content ranges from 1.0 x 10-9 to 3.6 10**-9 g/g in concretions from both oceans. Radium is more abundant in specimens from the Pacific Ocean (Ra = 3 - 12.7 x 10**-11 g/g) than from the Indian Ocean (1.5 - 5.2 x 10**-11 g/g). Analyses for Ca, Mn, Fe, Si, Ni, P, and ignition loss are also given. Radioactive equilibria between uranium, ionium, and radium are strongly disturbed throughout the concretions, and the RA/U and lo/U ratios generally exceed equilibrium ratios. Migration of radium from interior layers was established, so that neither determination of the ages of the concretions nor of their rates of growth can be considered reliable. The age of the concretions cannot exceed 800,000 years, and all grew within relatively short periods of time; there may have been "dormant" periods during growth. Estimates of growth rates are calculated from the radium and ionium contents; they show marked discordance.

La concepción pragmática de la verdad. Diálogo entre William James y Bertrand Russell

Fil: Di Berardino, María Aurelia. Universidad Nacional de La Plata. Facultad de Humanidades y Ciencias de la Educación; Argentina.