南极中山站近岸海冰生态学研究 Ⅱ．1992年冰下水柱浮游植物生物量的季节变化及其与环境因子的关系

自１９９２年４月１２日至１２月３０日对中山站附近内拉峡湾冰下水柱中浮游植物生物量以及环境因子的季节变化进行了测定。水中叶绿素ａ含量在０．０３－２１．４０ｍｇ／ｍ３之间波动，在覆冰期间，生物量基本上随深度的增加而下降；５－９月份各层次的生物量普遍低于０．５ｍｇ／ｍ３，８－９月份低于０．１ｍｇ／ｍ３。各层次中以水表含量的季节变化最为明显，成冰后在９月份形成低谷，于１２月中旬紧接着冰底水华的消失而形成单一峰值。生物量中微型浮游植物（＜２０μｍ）的比重在４－９月份的多数层次占有一半以上，１０月份后随着生物量的上升而下降，在水华期水表的比重最低，仅占总量的３．２％。其柱总生物量基本上与冰中生物量处于同一数量级，在冰藻水华期其量值甚至低于冰中生物量。营养盐（μｍｏｌ／Ｌ）的波动范围为ＰＯ４－Ｐ：０．３２－０．７９，ＳｉＯ３－Ｓｉ：２６．４７－６９．９２，ＮＯ３－Ｎ：１．４１－３１．７５，尽管水华期水表营养盐含量降至观测期间的最低点，但仍能满足冰下浮游植物的生长所需。光辐照度由于在冰水界面的量值仅为冰表入射光的不足５．３％至低于１％，成为水中产量最为可能的限制因子。

SEASONAL CHANGES OF CHLOROPHYLL A AND OCEANO GRAPHIC CONDITIONS UNDER FAST ICE OFF ZHONG SHAN STATION,EAST ANTARCTICA IN 1992

The chlorophyll a concentrations and oceanographic conditions under sea ice near Zhongshan Station(69°22′24″S,76°22′40″E) ,east Antarctica was monitored from April 12 to December 30 in 1992.The biomass measured as chlorophyll a were lower than 0.5mg/m 3 during wintertime,and even lower than 0.1mg/m 3 from July to September.The concentrations began to rise during spring and reached its maximum value of 21.40mg/m 3 in mid December in the water surface following the ice algal bloom,and then decreased quickly again.The ratios of nanoplankton(<20μm) biomass to the total phytoplankton biomass were commonly higher than 50% in winter but decreased following the increasing biomass in spring,the ratio in the water shrface was only 3.2% during the phytoplanton bloom. The nutrients were sufficent to support the growth of phytoplankton,but the concentrations decreased apparently during spring,and reached its lowest values of PO 4 P:0.32,SiO 3 Si:26.47,and NO 3 N:1.41(μmol/L) during phytoplankton bloom.The irradiance might be the prodominant factor to limit the phytoplankton biomass in water column under sea ice. Comparison of biomass in water column and sea ice shows that the phytoplankton biomass was less important when the sea surface was covered with sea ice. Because the primary production were mostly distributed in the bottom of ice and the surface water,the role of ice water interface in the ecosystem was very important.