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30 March 1997, Volume 9 Issue 1 Previous Issue    Next Issue
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RESEARCH ON THE SEDIMENTARY ENVIRONMENTAL CHANGES IN ELSON LAGOON AT BARROW AREA, ALASKAN ARCTICA 1997, 9 (1):  3-9.  Abstract ( 2128 )   PDF (538KB) ( 1297 )   Barrow is located in the northeast of Alaskan coastal plain ( 71°20′ N,156°40′W ),which is encircled by the Chukchi Sea in the west and the Beaufort Sea in the north.Thus,it is considered to be a key region for studying the land ocean interaction related to climatic and environmental changes.For the goals,an unfrozen 60 cm deep lake deposit core (AB67) was recovered at the water depth of 2m (2km to the bank of the Elson Lagoon ) by the use of Piston Corer.According to the measurements on 210 Pb of the upper sector ( 0￣20 cm ) and on the grain size of the whole core ,the sedimentary time span of the whole core (60 cm) is estimated to be about 450 years,i.e. 1540￣1990 AD. It can be stratigraphically divided into three sectors. The upper sector (0￣21 cm ) mainly consists of silt and clay ,and the lower sector ( 32￣60 cm ) mainly consists of fine sands and silts with small gravels,while the grain size of middle sector is between that of the two sectors.Grain size data showed that the driving force of sedimentation is stronger in the lower sector and weaker in the upper sector,while the driving force of sedimentation in middle sector is between that in lower and upper sector. The sortification and probability accumulation charts of the deposit samples showed the same trend. Related Articles | Metrics

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ECOLOGICAL STRUCTURE OF NEWLY FORMED SEA ICE IN THE WEDDELL SEA, ANTARCTICA Ⅰ. CHLOROPHYLL A AND NUTRIENTS 1997, 9 (1):  11-19.  Abstract ( 1844 )   PDF (276KB) ( 1313 )   Textural composition, chlorophyll a and nutrients (phosphate, nitrate and silicate) of newly formed sea ice of the Weddell Sea, Antarctica, were analyzed during the period of austral autumn in 1992. Frazil ice, congelation ice and mixture of frazil/congelation ice were main textural composition types, which were formed in related conditions at the sea. The mean concentrations of chlorophyll a and nutrients in the sea ice varied considerably with ice texture. The higher concentration of chlorophyll a occurred mostly in ice floe consisting predominantly or mainly of frazil ice. The concentration of nutrients showed an inverse relationship with frazil ice, being significantly lower than that in the congelation ice. This is due to subsequent microalgae growth using the available nutrients in the sea ice. The data by analysis of the one year old sea ice with higher chlorophyll a correlated to lower nutrients supports the extrapolation as above. Related Articles | Metrics

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DISTRIBUTIONS OF PHYTOPLANKTON,SIZE FRACTIONATED CHLOROPHYLL A AND PRIMARY PRODUCTIVITY IN PRYDZ BAY AND THE ADJACENT AREA DURING AUSTRAL SUMMER 1997, 9 (1):  20-29.  Abstract ( 1743 )   PDF (366KB) ( 1341 )   Size fractionated chlorophyll a , primary productivity, cell abundance, dominant species of phytoplankton and particulate organic carbon were observed in Prydz Bay and the adjacent area during austral summer of 1991/1992 (the 8th CHINARE). The results showed that there were obvious spatial zonation of above parameters in the studied area. Those were high in Zhongshan Bay, Davis Bay, the east surveyed region, and low in the west region of the surveyed area. The highest concentration of total chlorophyll a occurred in Prydz Bay and the adjacent continental shelf off shore (2.05±1.84mg/m 3). The higher productivity [>1000mgC/(m 2.d)] occurred in Zhongshan Bay and Davis Bay. The concentrations of micro (>20μm), nano with picoplankton (<20μm) contributed to total chlorophyll a were 57.3% and 42.7% separately. The contribution of nano with picoplankton was higher to total productivity (47.3%) than that to total chlorophyll a concentration. Related Articles | Metrics

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40 Ar/ 39 Ar AGES AND THEIR GEOLOGICAL SIGNIFICANCE OF THE VOLCANIC ROCKS OF MOUNT BOWLES FORMATION IN LIVINGSTON ISLAND, SOUTH SHETLAND ISLANDS 1997, 9 (1):  30-36.  Abstract ( 1862 )   PDF (430KB) ( 1357 )   The isotopic age of the volcanic rocks of the Mount Bowles Formation (MBF) outcropped on the eastern part of Livingston Island, South Shetland Islands, Antarctica have been remeasured by 40 Ar/ 39 Ar and laser microarea isochron age dating techniques. The results indicate that the isochron ages of 45D andesitic lava and 262 basaltic andesite are (105.62±2.11) Ma and (111.48±2.23)Ma respectively. The two good fit isochron lines give the 40 Ar/ 36 Ar initial ratio of 295.3 and 294.6, which are almost the same as the ratio of atmospheric argon (Neir value=295.5). That images no excess argon in the rocks and the isochron age being the real forming age. The 40 Ar/ 39 Ar plateau age of A9352 aplite is (96.7±1.6) Ma and the calculated isochron age is 96.6Ma, which suggests that the aplite occurred after lava eruption. These new ages further verify that the MBF volcanic rocks were formed during Cretaceous. Therefore, Cretaceous volcanic activity should have created a great impression on the whole Livingston Island and the MBF volcanic rocks, which had been covered by younger overburden, were influenced by the thermal event of Tertiary intrusives. Related Articles | Metrics

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ENVIRONMENTAL MAGNETISM OF MARINE SEDIMENTS FROM ANTARCTICA SINCE 15kaB.P. 1997, 9 (1):  37-45.  Abstract ( 1891 )   PDF (442KB) ( 1435 )   In this paper, environmental magnetism of two marine sediment cores NP95 1 and NG93 1 is systematically studied ( core NP95 1 was collected from Prydz Bay,Eastern Antarctica, and core NG93 1 was sampled from Great Wall Bay, Western Antarctica), and a series of paleoclimatic variations is obtained.Results show that the rock magnetic parameters well correspond to the paleoclimatic variations and sedimentary environmental changes. The NP95 1 well recorded the Heinrich event 1, Younger Dryas cold event and Bolling Allerod warm period, and the Heinrich event 1 occurred at 14.3kaB.P., Younger Dryas occurred at 11.7～10.3kaB.P..The boundary of Pleistocene and Holocene in Antarctica is 10.3 kaB.P.. In Holocene,two warm periods were recorded at about 10kaB.P. and 6.0kaB.P. with a little colder period between them. After 6.0kaB.P., two cores both recorded a cold climatic oscillation. Related Articles | Metrics

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AROMATIC COMPOUNDS IN SURFACE SEDIMENTS FROM BRANSFIELD STRAIT, ANTARCTICA 1997, 9 (1):  46-59.  Abstract ( 1770 )   PDF (451KB) ( 1188 )   The characteristics of components and ring number distribution of fluorescence aromatic compounds were studied by using gaschromatography and three dimension total scanning fluorescence. The aromatic compounds contain homologous series compounds of naphthalene, phenanthrene and fluorene.The amount of phenanthrene series is larger than that of other compounds. The next is fluorene series compounds, of which the dibenzothiophen, alkyl , and dialkyl dibenzothiophen are 24%～61%. The result of three dimension total scanning fluorescence indicates that the emission spectra of samples from Bransfield Strait, Antarctic are 350～450nm, the ratios of T 4/T 0 are 58%～67%, which attributes to the predominance of more than five ring compounds. Related Articles | Metrics

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SPATIO TEMPORAL VARIATIONS OF ENVIRONMENTAL FACTORS IN INTERTIDAL ZONE IN SUMMER IN THE FILDES PENINSULA, ANTARCTICA 1997, 9 (1):  55-59.  Abstract ( 1837 )   PDF (355KB) ( 1144 )   The environmental factors such as water temperature, salinity, nutrient salts (in the forms of PO 4 P, NO 3 N and SiO 3 Si) in the intertidal zone in summer in the Fildes Peninsula, Antarctica are analyzed. For the spatial distribution of water temperature, it is the highest in the high tide area, the next in the mid tide area and the lowest in the low tide area. The length of the time for the exposure of the intertidal zone and air temperature are the main factors influencing the water temperature change. As to the spatial distribution feature of the salinity, it is the lowest in the high tide area, the next in the mid tide area, and the highest in the low tide area.The amount of snowmelt from land infiltrated into the intertidal zone will influence the spatial distribution of salinity in the intertidal zone. The spatial distribution of the nutrients in the intertidal zone in the mid tide area is lower than that in the low tide area. The nutrients in the intertidal zone are mostly not terrigenous. Related Articles | Metrics

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OBSERVATION AND ANALYSES OF GEOMAGNETIC PULSATIONS AT ZHONGSHAN STATION, ANTARCTICA 1997, 9 (1):  60-67.  Abstract ( 1750 )   PDF (188KB) ( 985 )   The data of various geomagnetic pulsations observed at Zhongshan Station from Feb.9,1992 to Feb.9,1993 are analysed in this paper and the excitation mechanisms of pulsations at Antarctic polar cusp are discussed primarily. By the observation and analyses of geomagnetic pulsations at Zhongshan Station, the phenomena of upper atmospheric electromagnetic environment, interaction between solar wind and the magnetosphere etc. at Antarctic polar cusp can be further realized. Related Articles | Metrics

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THE QUALITY ANALYSIS OF FILDES DEFORMATION MONITORING NETWORK 1997, 9 (1):  68-72.  Abstract ( 1885 )   PDF (250KB) ( 1234 )   In this paper the synthetical quality estimate of West Antarctic Fildes deformation monitoring network is studied based upon statistical test theory, and the appreciable error testing, the reliability and the sensitivity of the deformation monitoring network is discussed also. By the processing and analysis for the real surveying date of the network the research results indicate that the network is helpful in monitoring crustal shear movement of Fildes Strait fault. Related Articles | Metrics

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HYDROCHEMICAL PROPERTIES OF LAKES IN LARSEMANN HILL,ANTARCTICA 1997, 9 (1):  73-79.  Abstract ( 1953 )   PDF (276KB) ( 1359 )   This paper presents hydrochemical properties of 13 lakes in Larsemann Hills,Antarctica.Investigations indicate that, in lake water, Na + and Cl - are predominant ions,but no CO 3 2- is present.Hence, all lakes belong to Na + group. The contents of nutrient substance (N, P, SiO 2) in lake water are rather low, whereas, inorganic nitrogen exists mainly in the form of NH 4 + N both in lakes and in snow.And the relatively high concentrations of Na +,Cl - and SO 4 2- , especially those ions in Big Lake,Mochou Lake and Heart Lake,apparently suggest that the precipitation of Larsemann area is dominated by oceanic conditions.The contents of trace elements range from 0.01 to 2.0 μg/l,which are approximately the same as that of hydroesphere in general. Related Articles | Metrics

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THE MEASUREMENTS AND ANALYSES OF OZONE PROFILE DURING THE “OZONE HOLE” PERIOD OVER ZHONGSHAN STATION,ANTARCTICA 1997, 9 (1):  80-84.  Abstract ( 1765 )   PDF (132KB) ( 1306 )   During the springtime Antarctic Ozone Hole,the decrease of total column amount of O 3 is mainly due to the decrease of stratospheric O 3 amount. It is very important to study the atmospheric ozone vertical profile in order to study the formation and development of the Antarctic Ozone Hole. This paper chiefly analyzes the changing of the atmospheric ozone vertical distribution during the 1995 Antarctic Ozone Hole,which is measured by a Brewer Ozone Spectrophotometer and inversed by the Umkehr method.We also compare the ozone vertical distribution before,during and after the Antarctic Ozone Hole,and compare our results with the data of other foreign stations. Here we point out that the decrease of atmospheric ozone over Zhongshan Station during the Antarctic Ozone Hole is chiefly in the lower stratospere(14～25km).This shows that the heterogeneous reaction,which happens on the surface of the polar stratospheric cloud,also chiefly happens at the altitude of 14～25km. Related Articles | Metrics