The MV Rena shipwreck: time-critical scientific response and environmental legacies

ABSTRACT

The sinking of the MV Rena on Astrolabe Reef (Otaiti) in the Bay of Plenty, New Zealand, resulted in the release of oil and ship debris, including dangerous goods carried as cargo. Two key questions of concern to the public and environmental managers were posed immediately: what was the impact of the Rena oil spill and how long would it take for the marine environment to recover? The research that began immediately after the ship grounded provided answers, as documented in this special issue.     

THE HYDROGEOLOGY OF GHANA

SUMMARY

Many hydrological systems exhibit long periods of quiescent behaviour, broken only occasionally by short periods of comparatively intense activity. Clear examples arise in stream run-off measurements and in ground water table observations. The number of measurements recorded can then be considerably reduced by reducing the frequency of recording over the quiescent periods. The paper describes an algorithm whereby this reduction is attained in an optimum manner. When recordings can be accepted directly by a computer, the algorithm simply provides a translation programme Whereby the quality of data may be very considerably reduced. Other applications are, however, discussed.

The problems of Optimum representations is first presented, and choices of norm indicated. Using a particular norm, it is shown that the optimum representation is characterised, under certain limiting conditions, by the property that the second moments of the second derivatives are constant over all optimum intervals. This characterisation is used to construct an iterative difference scheme, whereby a certain truncation error is accepted. Sufficient conditions for stability of the scheme are determined and these incorporated into a computer programme. The programme has been tested on a variety of data with satisfactory results. In conclusion, a further development of the method is indicated.     

Alteration of five organic compounds by glow discharge plasma and UV light under simulated Mars conditions

The Viking missions to Mars failed to detect any organic material in regolith samples. Since then, several removal mechanisms of organic material have been proposed. Two of these proposed methods are removal due to exposure to plasmas created in dust devils and exposure to UV irradiation. The experiments presented here were performed to identify similarities between the two potential removal mechanisms and to identify any compounds produced from these mechanisms that would have been difficult for the Viking instruments to detect. Five organic compounds, phenanthrene, octadecane, octadecanoic acid, decanophenone and benzoic acid, were exposed to a glow discharge plasma created in simulated martian atmospheres as might be present in dust devils, and to UV irradiation similar to that found at the surface of Mars. Glow discharge exposure was carried out in a chamber with 6.9 mbar pressure of a Mars like gas composed mostly of carbon dioxide. The plasma was characterized using emission spectroscopy and found to contain cations and excited neutral species including carbon dioxide, carbon monoxide, and nitrogen. UV irradiation experiments were performed in a Mars chamber which simulates the temperature, pressure, atmospheric composition, and UV fluence rates of equatorial Mars. The non-volatile residues left after each exposure were characterized by mass loss, infrared spectroscopy and high resolution mass spectrometry. Oxidized, higher molecular weight versions of the parent compounds containing carbonyl, hydroxyl and alkenyl functional groups were identified. The presence of these oxidized compounds suggests that searches for organic material in soils on Mars use instrumentation suitable for detection of compounds which contain the above functional groups. Discussions of possible reaction mechanisms are given.     

Cytochrome P-450 isozymes in salmonids determined with antibodies to purified forms of P-450 from rainbow trout

Purification of cytochromes P-450 from liver microsomes of β-naphthoflavone (BNF)-fed rainbow trout yielded three apparently homogeneous forms. The major form (LM_4b)^* appears to be a P-448 type of cytochrome. A minor form (LM_4a), having properties very similar to LM_4b, was also obtained. In addition, a P-450 form (LM₂) was isolated, with properties quite different from LM_4a or LM_4b, including a high rate of aflatoxin B₁ (AFB₁) metabolism (Williams & Buhler, 1983c). Antibodies to all three forms were obtained from rabbits. The IgGs prepared against LM_4a and LM_4b both cross-reacted (forming lines of identity) equally well with both antigens on Ouchterlony plates. Rat P-448 cross-reacted (without lines of identity) with both LM_4a- and LM_4b-IgG. LM_4b-IgG was much more effective than LM_4a-IgG for inhibition of LM_4a or LM_4b reconstituted benzo[a]pyrene (BP) hydroxylase, suggesting that these two antibodies recognize different antigenic sites. The LM₂-IgG did not cross-react with any of the other rat or trout cytochromes P-450 examined. Levels of LM₂ and LM_4b in microsomes from untreated, polychlorinated biphenyl (PCB), phenobarbital (PB) or BNF-treated trout were estimated with an immunological technique involving electrophoresis on SDS-PAGE, followed by transfer to nitrocellulose and staining with either LM ₂ - or LM_4b -IgG. The ratio of in microsomes from PCB- or BNF-treated rainbow trout was much higher than 1, whereas the reverse was true with microsomes from untreated rainbow trout. These results are consistent with previous observations (Vodicnik et al., 1982) that pretreatment with BNF induced the synthesis of a P-448 type cyytochrome, presumably responsible for the great increase in the metabolism and activation of BP seen in these fish. Conversely, pretreatment with PB did not affect the levels of either LM₂ or LM_4b. This specific immunological technique should make it possible to assay the levels of these P-450 and P-448 isozymes in various strains of rainbow trout and other species of fish. In addition, the effect of age, sex, diet and exposure to P-450 and P-448 inducers could be examined and, perhaps, utilized to predict the relative risk of certain populations to pollutants activated by these different isozymes.     

CYP1B1 knockdown does not alter synergistic developmental toxicity of polycyclic aromatic hydrocarbons in zebrafish (Danio rerio)

Polycyclic aromatic hydrocarbons (PAHs) are contaminants increasing in the environment largely due to burning of fossil fuels. Our previous work identified a synergistic toxicity interaction in zebrafish embryos occurring when PAHs that are agonists for the aryl hydrocarbon receptor (AHR) co-occur with PAHs that are CYP1A inhibitors. This toxicity is mediated by the AHR2, and morpholino knockdown of CYP1A exacerbated toxicity. This study tested two hypotheses: (1) in the absence of functional CYP1A, metabolism of PAHs is shunted towards CYP1B1, which has been shown in mammals to produce more reactive metabolites of PAHs; alternatively, (2) CYP1B1 serves a protective role similar to CYP1A. We used a morpholino approach to knockdown CYP1B1 alone and in co-knockdown with CYP1A to determine whether we could alter deformities caused by synergistic toxicity of PAHs. CYP1B1 knockdown was not different from non-injected controls; nor were CYP1B1+CYP1A co-knockdown deformities different from CYP1A knockdown alone. These data suggest that CYP1B1 is not a significant factor in causing synergistic toxicity of PAHs, nor, in contrast to CYP1A, in providing protection.     

Evidence for paleolakes in Erythraea Fossa, Mars: Implications for an ancient hydrological cycle

There is now widespread agreement that the surface of Mars underwent some degree of fluvial modification, but there is not yet full understanding of its surface hydrological cycle and the nature of standing bodies of water, rivers, and precipitation that affected its surface. In this paper we explore Erythraea Fossa (31.5 W, 27.3 S), a graben adjacent to Holden crater, which exhibits strong evidence that it once housed a chain of three lakes, had overland water flow, and was subject to precipitation. The inlet valley, outlet valley, and fan morphologies in the paleolakes are used to qualitatively discern the hydrologic history of the paleolakes; based on topography constraints, the three basins combined once held 56 km³ of water. Depositional features within the basins that change with drainage area and nearby valleys that start near drainage divides indicate that the paleolakes may have been fed by precipitation driven runoff. This suggests the presence of an atmosphere, at least locally, that was capable of supporting a hydrological cycle.