What’s Happening with the Ozone Hole?

Discovered by Schonbein in 1839, ozone (03) is a highly reactive and toxic form of oxygen with a pungent smell. It occurs both naturally and as an atmospheric pollutant at ground level. Ozone is found in low concentrations in the stratospheric layer of the earth's atmosphere, 10 to 50 km above the surface, where it acts to shield the earth from solar UV radiation, between 220 and 320mm (Christie, 2000). Measurements of stratospheric ozone began at Oxford in 1924 where Dobson and Han•ison found seasonal variations in ozone levels. They also found significant variabllity in short term ozone levels, later recognised as being associated with weather patterns and changes in surface air pressure. The units used for measuring ozone concentrations ate known as Dobson units (DU) and represent the amount of ozone in a square centimctle column through the atmosphere. A typical measurement about 300 DU, which means that if you took all the ozone in a vertical column above the instrument down to sea level, it would form a 3mm thick layer. The need for a global network of ozone monitonng stations was soon recognised and with the International Geophysical Year of 1957 - 58 the network expanded to include the first measurements of ozone in Antarctica, from the British Station at Halley Bay on the coast of the Weddell Sea. It was from here that regular ozone monitoring, from the 1960s to the mid 1980s, led to the 1985 report in "Nature"of a 50% spring-time depletion of the ozone layer above Antarctica. In this paper, Farman, Gardiner and Shanklin (1985) linked the reduction in ozone levels to increases in inorganic chlorine and the very low temperatules of the Antarctic stratosphere. The ozone hole had been discovered. Discovered by Schonbein in 1839, ozone (03) is a highly reactive and toxic form of oxygen with a pungent smell. It occurs both naturally and as an atmospheric pollutant at ground level. Ozone is found in low concentrations in the stratospheric layer of the earth's atmosphere, 10 to 50 km above the surface, where it acts to shield the earth from solar UV radiation, between 220 and 320mm (Christie, 2000). Measurements of stratospheric ozone began at Oxford in 1924 where Dobson and Han•ison found seasonal variations in ozone levels. They also found significant variabllity in short term ozone levels, later recognised as being associated with weather patterns and changes in surface air pressure. The units used for measuring ozone concentrations ate known as Dobson units (DU) and represent the amount of ozone in a square centimctle column through the atmosphere. A typical measurement about 300 DU, which means that if you took all the ozone in a vertical column above the instrument down to sea level, it would form a 3mm thick layer. The need for a global network of ozone monitonng stations was soon recognised and with the International Geophysical Year of 1957 - 58 the network expanded to include the first measurements of ozone in Antarctica, from the British Station at Halley Bay on the coast of the Weddell Sea. It was from here that regular ozone monitoring, from the 1960s to the mid 1980s, led to the 1985 report in "Nature"of a 50% spring-time depletion of the ozone layer above Antarctica. In this paper, Farman, Gardiner and Shanklin (1985) linked the reduction in ozone levels to increases in inorganic chlorine and the very low temperatules of the Antarctic stratosphere. The ozone hole had been discovered

The effect of exercise and dietary cholesterol on cholesterol synthesis in the hamster

Physical inactivity and elevated plasma cholesterol are well characterized risk factors for the development of coronary heart disease (CHD). Consequently, manipulation of exercise intensity and dietary cholesterol may favourably alter lipid metabolism to reduce this risk. The present study examined both independent and interactive effects of exercise and dietary cholesterol on in vivo hepatic and intestinal cholesterol synthesis as well as plasma total and high density lipoprotein (HDL) cholesterol levels in hamsters. Male Syrian hamsters were randomized into one of i) low dietary cholesterol (0.03% w/w) sedentary (LC-S), ii) low cholesterol exercise (LC-E), iii) high cholesterol (0.12% w/w) sedentary (HC-S) or iv) high cholesterol exercise (HC-E) groups. Exercised hamsters were trained to run at increasing speeds on a motorized treadmill for 90 minutes daily over a two week period. Animals were subsequently run for 1 week at 70% of VO₂ max for 90 minutes each day. Cholesterol synthesis was determined by measuring the rate of incorporation of into digitonin precipitable sterols in liver and small intestine over 2 hours following IP injection of ³H₂O. Plasma total cholesterol was significantly increased by dietary cholesterol in HC versus LC groups independent of an exercise lowering effect in HC-E animals. HDL cholesterol was also elevated in response to dietary cholesterol in HC groups, however LC-E hamsters had lower plasma HDL cholesterol than any other group through an interaction between exercise and diet. Incorporation of ³H into liver cholesterol was increased in HC-S versus LC animals, whereas exercise lowered hepatic sterol synthesis in HC-E by an exercise and diet interaction. Although exercise did not affect intestinal cholesterol synthesis, dietary cholesterol significantly decreased intestinal cholesterol synthesis in HC when compared with LC groups. Thus both plasma total cholesterol and small intestine responded characteristically to changes in dietary cholesterol levels, in opposition to liver cholesterol synthesis, which showed a compensatory increase to the attenuation of intestinal sterol synthesis. The exercise induced decrease evident in plasma cholesterol levels and hepatic cholesterol synthesis was not, however, observed in the small intestine. Therefore the independent response of liver and small intestine to exercise and dietary cholesterol level in this study indicate important differences in the manner through which these organs regulate whole body cholesterol balance.Land and Food Systems, Faculty ofGraduat

The Study Of A Colloidal Crystal Using Ultra Small-Angle X-Ray-Scattering(USAXS)

USAXS, using the Bonse-Hart twin crystal diffractometer system, has been developed at a synchrotron source for the study of colloidal dispersions and other heterogeneous systems [1]. Many improvements have been made, and the full potential of this newsly enhanced scattering system in both scientific and industrial fields is only just beginning to be realised [2]. One well-characterised commercial colloidal dispersion, a highly monodisperse colloidal latex, has shown some very interesting results using the improved system. At high concentrations some sharp Bragg Peaks have been observed in the scattering profile. The eperimental structure factor for the colloidal latex clearly shows at least five scattering peaks, the positions of which may be used to identify the structure of the ordered colloid. This structure is thought to be randomly close packe

Climate change linked to drought in Southern Madagascar

Southern Madagascar experienced a prolonged drought over the last five years, but whether these conditions are a manifestation of global climate change has been unclear. Here, we document trends beginning as early as 1980 towards a later rainy-season onset across three distinct remotely sensed indicators: precipitation, soil moisture, and vegetation greenness. All three indicators closely covary, particularly over the last decade when satellite observational resolution and accuracy is greatest. Furthermore, observed soil moisture trends early in the rainy season agree with the mean from CMIP6 historical and SSP5-8.5 simulations, but are distinct from pre-industrial control simulations, implicating anthropogenic changes in radiative forcing as the source of the trends. Physically, these models simulate a poleward migration of the mid-latitude jet that leads to a delay in the seasonal steering of storm tracks over Southern Madagascar. Soil moisture trends driven by anthropogenic forcing made the recent drought significantly more likely over 2017–2022 (p < 0.01), and such droughts are expected to become increasingly likely over this century. These results indicate that, although Madagascar has not substantially contributed to global greenhouse gas emissions, farmers in Southern Madagascar will need to adapt to drier conditions early in the rainy season as a consequence of global climate change

Biological nitrogen fixation and biomass production in the understorey vegetation of an organic apple orchard in Canterbury, New Zealand

One of the basic requirements for sustainable management of soils is to ensure that soil fertility is maintained in a productive state and conditions so as to enable the soil to continue to provide viable economic yields with minimum degradation of soil quality and quantity. The practice of supplying nitrogen to fruit trees from biological nitrogen fixation by pasture legumes in the understorey vegetation of orchards is a sustainable means of maintaining soil fertility. Quantitative field measurements of amounts of biological nitrogen fixation and biomass production by three different kinds of understorey vegetation in an organic apple orchard in Canterbury New Zealand was conducted over a period of two years. Results obtained showed that biological nitrogen fixation varied from 118 to 126 kg N ha⁻¹ over the period of two years and herbage production varied from 8 to 12 t ha⁻¹. Nitrogen fixation was significantly correlated with clover dry matter production. Results were affected by seasons and understorey management practices. Implications of these results are discussed with respect to management strategies for enhancing biological nitrogen fixation in organic orchards

Square Peg Round Hole: A Study of Non Governmental Organisations’ Participation in the Antarctic Treaty System

Involvement of both national and international Non-Governmental Organisations (NGOs) in the Antarctic occurred even before there was a formal management regime for this vast region of the south. Their calls for peace and a co-operative approach came amongst claims for sovereignty. In 1958/59 the International Geophysical Year saw a major change in direction for the governance of the continent which led to an agreement, by 12 nations, on the Antarctic Treaty and the consequent development of a unique legal system. Since then, involvement in this system has been primarily limited to nations, with interested organisations at times struggling to have an effective voice. This paper examines the involvement of Non-Governmental Organisations in the govemance of Antarctica, the positive contributions they have made and the problems that have arisen. A new "Advisor" status is recommended to provide a mechanism by which Non Governmental Organisations can be more involved in the Antarctic Treaty System. In addition, governments are encouraged to include national Non-Governmental Organisations in their national Policy formation and delegation processes. This would ensure a more robust regime based on trust and a common interest in the stewardship of this remarkable region. Involvement of both national and international Non-Governmental Organisations (NGOs) in the Antarctic occurred even before there was a formal management regime for this vast region of the south. Their calls for peace and a co-operative approach came amongst claims for sovereignty. In 1958/59 the International Geophysical Year saw a major change in direction for the governance of the continent which led to an agreement, by 12 nations, on the Antarctic Treaty and the consequent development of a unique legal system. Since then, involvement in this system has been primarily limited to nations, with interested organisations at times struggling to have an effective voice. This paper examines the involvement of Non-Governmental Organisations in the govemance of Antarctica, the positive contributions they have made and the problems that have arisen. A new "Advisor" status is recommended to provide a mechanism by which Non Governmental Organisations can be more involved in the Antarctic Treaty System. In addition, governments are encouraged to include national Non-Governmental Organisations in their national Policy formation and delegation processes. This would ensure a more robust regime based on trust and a common interest in the stewardship of this remarkable region