Science, environment and resources in Antarctica

Earlier views regarding the relative insignificance of Antarctic science have been rudely shattered by recent developments. The International Geophysical Year (IGY) of 1957–1958 represented a major turning point for research in Antarctica, even if it is a mistake to believe that no useful scientific work was performed during the pre-IGY period. The IGY provided a sound foundation for the development of Antarctic scientific activity in a wide range of disciplines, including glaciology, atmospheric sciences and medicine. The intrinsic value of research in Antarctica is reinforced by its relevance to an improved understanding of global environmental systems; stratospheric ozone depletion was first identified at Halley base station. Minerals, as yet unproven, have highlighted the conservation problems inherent in the utilization of any Antarctic resources. Marine living resources are at present under threat of over-exploitation in some areas. The 1990s hold the promise for a brighter scientific future for Antarctica, but only as long as the Antarctic Treaty system continues in operation.     

A Review of Some Environmental Issues Affecting Marine Mining

Abstract

This article reviews information recently available from existing marine and coastal mining for responses to environmental issues affecting marine mining at different depths. It is particularly but not exclusively concerned with those issues affecting seabed biodiversity impact and recovery. Much information has been gathered in the past 10 years from shallow mining operations for construction aggregate, diamonds, and gold, from coastal mines discharging tailings to shallow and deep water, and from experimental deep mining tests. The responses to issues identified are summarized in a series of eight tables intended to facilitate site-specific consideration. Since impacts can spread widely in the surface mixing layer SML, and can affect the biologically productive euphotic zone, the main issues considered arise from the depth of mining relative to the SML of the sea. Where mining is below the SML, the issue is whether it is environmentally better to bring the extraction products to the surface vessel for processing (and waste discharge), or to process the extraction products as much as possible on the seabed. Responses to the issues need to be site-specific, and dependent on adequate preoperational environmental impact and recovery prediction. For deep tailings disposal from a surface vessel, there are four important environmental unknowns: (1) the possible growth of “marine snow” (bacterial flocs) utilizing the enormous quantities of fine tailings particles (hundreds or thousands of metric tons per day) as nuclei for growth, (2) the possibility that local keystone plankton and nekton species may migrate diurnally down to and beyond the depth of deep discharge and hence be subjected to tailings impact at depth, (3) the burrow-up capability of deep benthos and their ability to survive high rates of tailings deposition, and (4) the pattern and rate of dispersion of a tailings density current through the deep water column from discharge point to seabed. Actions to obtain relevant information in general and site-specifically are suggested.     

Ocean tides around New Zealand

The distribution of amplitude and phase for eight ocean tidal constituents (M₂, S₂, N₂, K₂, K₁, O₁, P₁, Q₁) is presented as tidal maps for the New Zealand area. The distribution was calculated using a barotropic tidal model driven by TOPEX/ Poseidon data on the outer ocean boundaries. The maps exhibit the known features of the tides in this area such as a complete rotation of the semi‐diurnal tides around New Zealand and the reduced spring‐neap variations on the east coast. They also point out several new features for which there are few or no observations, such as diurnal trapped waves and shelf waves. A comparison of the model results with observations shows that sea level errors are within 0.1 m in amplitude and 10° in phase for the largest constituents at all locations, including sites where the data are of low quality and where the geometry is not adequately resolved. For locations where the geometry is adequately represented and the observations are of high quality, sea level errors are within 0.02 m in amplitude and 7° in phase. These results represent the most accurate and highest resolution calculations of tides and currents yet attained for this area.     

Oral Histories in Meteoritics and Planetary Science – XV: John Wood

Abstract– John Wood ( Fig. 1 ) was trained in Geology at Virginia Tech and M.I.T. To fulfill a minor subject requirement at M.I.T., he studied astronomy at Harvard, taking courses with Fred Whipple and others. Disappointed at how little was known in the 1950s about the origin of the earth, he seized an opportunity to study a set of thin sections of stony meteorites, on the understanding that these might shed light on the topic. This study became his Ph.D. thesis. He recognized that chondrites form a metamorphic sequence, and that idea proved surprisingly hard to sell. After brief service in the Army and a year at Cambridge University, John served for 3 years as a research associate with Ed Anders at the University of Chicago. He then returned to the Smithsonian Astrophysical Observatory in Cambridge, Massachusetts, where he spent the remainder of his career. At Chicago, he investigated the formation of the Widmanstätten structure, and found that the process informs us of the cooling rates of iron meteorites. Back in Cambridge, he collaborated with W. R. Van Schmus on a chondrite classification that incorporates metamorphic grade, and published on metal grains in chondrites, before becoming absorbed by preparations for the return of lunar samples by the Apollo astronauts. His group’s work on Apollo samples helped to establish the character of the lunar crust, and the need for a magma ocean to form it. Wood served as President of the Meteoritical Society in 1971–72 and received the Leonard Medal in 1978.

Figure 1 Open in figure viewer PowerPoint John Wood.     

On-Orbit Degradation of Solar Instruments

We present the lessons learned about the degradation observed in several space solar missions, based on contributions at the Workshop about On-Orbit Degradation of Solar and Space Weather Instruments that took place at the Solar Terrestrial Centre of Excellence (Royal Observatory of Belgium) in Brussels on 3 May 2012. The aim of this workshop was to open discussions related to the degradation observed in Sun-observing instruments exposed to the effects of the space environment. This article summarizes the various lessons learned and offers recommendations to reduce or correct expected degradation with the goal of increasing the useful lifespan of future and ongoing space missions.     

Long-term variations in north-south asymmetry of solar activity

We present a new set of data on relative sunspot number (total, northern hemisphere, and southern hemisphere), taken for the 37-yr period 1947 to 1983; this constitutes a particularly coherent and consistent set of data, taken by the same observer (Hisako Koyama) using the same observing instrument. These data are combined with earlier data (White and Trotter, 1977) on the variation of sunspot areas for both solar hemispheres from 1874 to 1971. The combined data, covering 110 years and 10 solar cycles, are examined for periodicity in solar activity north-south asymmetry. We show that, in general, northern hemisphere activity, displayed as either An/(An + As) or Rn/(Rn + Rs), peaks about two years after sunspot minimum. This peak is greater during even cycles, pointing to a 22-yr periodicity in north-south asymmetry in solar activity, suggesting that the asymmetry is related to the 22-yr solar magnetic cycle. We demonstrate that the largest and most protracted period of northern-hemisphere activity excess in the last 110 years has occurred from 1959 to 1970; we show that there is a strong correlation between northern activity excess and a cosmic-ray density gradient perpendicular to the ecliptic plane, pointing southward, which is evident in cosmic-ray diurnal variation data from the Embudo underground cosmic-ray telescope.