Archive

30 June 1999, Volume 11 Issue 2 Previous Issue    Next Issue
---
Contents


For Selected:

Download Citations EndNote Ris BibTeX

Toggle Thumbnails

Contents

Select

POST DEPOSITIONAL MODIFICATION OF NO - 3 IN SNOW LAYERS AT EAST ANTARCTICA AND AT THE HEADWATER OF URUMCHI RIVER 1999, 11 (2):  4-10.  Abstract ( 1673 )   PDF (421KB) ( 1236 )   Acidic species, such as Nitrate, in polar snow and firn layers are “reversibly” deposited, and are sufficiently volatile to undergo significant post depositional exchange between snow/firn and the atmosphere. Through comparison of the snowpit and snowpack nitrate concentrations from central East Antarctica and the headwater of Urumchi River, we conclude that the nitrate peaks in the uppermost surface snow layers in central Antarctica are not related to an atmospheric signal and must account for post depositional effects. Such effects, however, are not found in the surface snowpack nitrate profiles from the headwater of Urumchi River. Two reasons may account for the post depositional difference. At first, nitrate in the polar snow and firn layers appears to be hydrated ion, which can be taken up by the atmosphere, while at the headwater of Urumqi River mainly as mineral ion, which assembles the behavior of aerosol derived species that are “irreversibly” deposited and do not undergo significant post depositional exchange with the atmosphere. Secondly, the chemical features of the snow and ice on the Antarctica are mainly determined by wet deposition, to the contrary, dry deposition is more significant at the headwater of Urumqi River than that on the East Antarctic Plateau. Related Articles | Metrics

Select

STUDY ON ECOLOGICAL STRUCTURES OF COASTAL LAKES IN ANTARCTIC CONTINENT 1999, 11 (2):  11-22.  Abstract ( 1800 )   PDF (485KB) ( 1513 )   Coastal region at the Antarctic continent,where is under the influences both of ocean and ice sheet,as well as many humen activities,could be considered as a fragile zone in Antarctic ecological environment. Lakes,there are many in the region,present much differences from each other in physical chemical features because of individual evolutionary history in their geographical environments,and suffer from different outside factors such as climite changes and precipitation. Thus,it results in respective biological distribution and ecological structure in lakes. The present paper reports the results from the studies of chemical components,species distributions and community structures,which mainly consisted of plankton in lakes in the Vestfold Hills and the Larsemann Hills,East Antarctica. It is also discussed that the biological diversities and nutrient relationships of these different types of lakes. Therefore,to provide more scientific basis for monitoring of climate changes and environmental protection in Antarctica. Related Articles | Metrics

Select

RESEARCH ON THE STRUCTURE AND RELATIONSHIP OF TERRESTRIAL, FRESHWATER, INTERTIDAL AND SHALLOW SEA ECOSYSTEMS IN FILDES PENINSULA, ANTARCTICA 1999, 11 (2):  23-35.  Abstract ( 1810 )   PDF (289KB) ( 1988 )   In this paper, we synthesized and analysed the structure and the interrelationship of the four ecosytems: terrestrial ecosystem, freshwater ecosystem, intertidal ecosystem, and shallow sea ecosystem in Fildes Peninsula, Antarctica, based on the research results during the past 10 years in this region, and also on the related results in other regions of Antarctica. Through our analysis, the nutrient flow integrates the four ecosystems as a whole. During the process of nutrient flow, the role of animals is very important, for example, sea birds redistribute the nutrient among the four ecosystems through their activity of breeding, feeding etc. The physical impact is also unignorable, for example, the rainfall, runoff, and tidal current bringing the nutrients from one ecosystem to another. Related Articles | Metrics

Select

A STUDY ON CHOLOROPHYLL A CONTENT AND ITS VARIATION IN GREAT WALL BAY,ANTARCTICA DURING THE AUSTRAL SUMMERS FROM 1992 TO 1995 1999, 11 (2):  36-44.  Abstract ( 1782 )   PDF (423KB) ( 1219 )   During three successive austral summers from Dec. to March of 1992/1993,1993/1994 and 1994/1995,investigation was carried out on phytoplanktonic chlorophyll a content in Great Wall Bay,Antarctica.The results showed that among the three summers the concentration of chlorophyll a in the summer of 1992/1993 was the highest with an average value of 3.79 mg/m 3 ,the range of chlorophyll a variation in this year was the largest,too. The year to year variation of average value of chlorophyll a was 3.79 mg/m 3 (1992/1993)>1.80 mg/m 3 (1993/1994)>1.20 mg/m 3 (1994/1995).The variation range of chlorophyll a was 10.10 mg/m 3 (1992/1993)> 6.57 mg/m 3 (1993/1994)> 2.41 mg/m 3 (1994/1995). Compared with chlorophyll a concent in austral summer in other area of Antarctica,the chlorophyll a in Great Wall Bay in the three year was relatively high though it was lower than that of 11.60 mg/m 3 in Jan. 1959 in Gerlache Strait and 56.10 mg/m 3 in Dec. 1961 in McMurdo Sound. The vertical distribution of chlorophyll a in water column was also presented. Related Articles | Metrics

Select

COMPARISONS OF ANTARCTIC METEORITES AND DESERT METEORITES 1999, 11 (2):  45-58.  Abstract ( 1708 )   PDF (390KB) ( 1740 )   Meteorite samples would be better preserved in Antarctic ice sheet and hot arid semi arid region. Up to date, meteorite scientists have searched only about 2500km 2 of blue ice and recovered around 15,000 meteorite specimens. More than 2000 meteorite specimens are recovered in Africa, Sahara desert, Western Australia and Roosevelt County(New Mexico and West Texas) desert regions. Differences between the Antarctic meteorites and desert meteorites have been noted since their preservation and climate conditions are different. antarctic meteorites have long terrestrial age, contamination from Earth is smalll and they show remarkable little weathering, in contrast with Antarctic meteorites, desert meteorites have short terrestrial age, contamination from Earth is serious and weathering degree is large. Major meteorite types and their frequency of Antarctic and desert meteorites are similar with modern fall meteorites. The variations of the flux of meteorite types with time are not observed, but abundances of new and unique meteorite types are higher. According to meteorite source we classified these meteorites as asteroid meteorite and planetary meteorite. The study on new and unique meteorite types are useful for understanding continuous chemical fractionation of early solar nebula and horizonal variation of lunar crust and Martian surface. Related Articles | Metrics

Select

ANTARCTIC PACK ICE SEAL 1999, 11 (2):  59-65.  Abstract ( 1842 )   PDF (303KB) ( 2382 )   As top predators,seals are likely to be sensitive to changes in the dynamics of ecosystems and,in particular,to variations in the flow of photosynthetically fixed carbon to higher levels in the food chain caused by climatic or ecological changes,pack ice seals are excellent indicators of large scale environmental change and,on a smaller scale, variations in seal distribution, abundance and features of their behaviour and physiology in different locations, years and seasons, can provide insights into changes in oceanographic features,pack ice seals could be used as free ranging platforms for oceanographic instruments to record and play(via satellites)data on sea temperature, salinity and ambient light at depth.There is also an urgent need to assess their functional significance in Southern Ocean ecosystems. The questions to be asked concern:the causes and scales of variation in their distribution and abundance;explanations of the greater abundane of crabeater seals;whether there are more Antarcitc seals in relation to primary production than in other regions and if so why;why their life histiory parameters fluctuate in a periodic fashion;why these parmaeters and their observed densities have changed over the past 30 years;how their diets and foraging strategies have adapted to optimize utilization of their food resources whether they have physiological and behavioural adaptations that make them unusually efficient ecologically;how much carbon they transfer to the atmosphere;and whether there are physiological condition of behavioural indices that could be used to appraise the pack ice ecosystem through studies of these seal populations? The APIS programme can be expected to produce information of value to several Antarctic research programmes and inter governmental organizations, These include CEP,CCAS,CCAMLR,(including CEMP),SO GLOBEC,SCOR,SO JGOFS,SCAR GLOCHANT, and IWC.The period of operation of the programms is from the 1995-1996 season through to the 1999-2000 season, with a major logistic effort envisaged for the 1998-1999 season. Related Articles | Metrics

Select

PROGRESS AND APPLICATION PROSPECTS IN THE STUDY ON ANTARCTIC COLD ADAPTED MICROORGANISMS 1999, 11 (2):  66-75.  Abstract ( 2127 )   PDF (445KB) ( 2964 )   For the uniquely geographic and climatic features in Antarctic, there are abundant resources of cold adapted microorganisms, and these microorganisms possess specially genetic and physiological and biochemical properties. Microorganisms act as an important role in the ecosystems in Antarctica, and they possess a considerable potential in basic research and biotechnological application (waste treatment at ambient temperatures, enzymology, food industry, medicine),too. This article briefly describes the general situations of researching in antarctic cold adapted microorganisms and researching achievements (emphasized on microbiological physiology, biochemistry and gene) in recent years, and make further discussion on prospects of these cold adapted microorganisms in application. Related Articles | Metrics

Select

SHORTWAVE FADING CHARACTERS FOR THE CIRCUITS OF MOSCOW AND IRKUTSK TO THE GREAT WALL STATION IN ANTARCTICA 1999, 11 (2):  76-83.  Abstract ( 1857 )   PDF (341KB) ( 1264 )   The two transpolar shortwave time signal circuits,Moscow and Irkutsk to the Great Wall Station in Antarctica, are used to study the fading characters for shortwave long circuit.The ionospheric shortwave channels for the two circuits are rapid fading channels,its signal amplitude fading obeys the Rayleigh distribution essentially and this distribution is independent of time,frequency,distance and geographic location.The fading depth is different for the two circuits. For Moscow to the Great Wall Station circuit,the lower the frequency,the larger the fading depth.But for Irkutsk to the Great Wall Station circuit,there is little relationship between the fading depth and frequency.It seems that the relationship between fading depth and frequency is controlled by the factors such as location,distance etc.The higher the frequency, the higher the fading rate for the two circuits. Related Articles | Metrics