楚科奇海及其海台区粒度分级叶绿素a与初级生产力

The Size-fractionated chlorophyll a concentration and primary productivity in the Chukchi Sea and its northern Chukchi Plateau

2003年夏季中国第二次北极科学考察期间,在楚科奇海及其海台区进行了叶绿素a浓度与初级生产力的现场观测。结果表明,观测海区叶绿素a浓度范围为0.009～30.390μg/dm3。表层浓度为0.050～4.644μg/dm3,平均值为(0.875±0.981)μg/dm3;陆架区次表层和底层的浓度高于表层,海台区深层水的浓度较低,200m层的浓度为(0.015±0.007)μg/dm3。水柱平均叶绿素a浓度区域性特征明显,陆架区高于海台区。R断面进行3趟重复观测,平均叶绿素a浓度分别为(2.564±1.496)μg/dm3,(1.329±0.882)μg/dm3和(0.965±0.623)μg/dm3,浓度呈下降趋势。观测站潜在初级生产力为0.263～4.186mgC/(m.3h),陆架区平均潜在初级生产力((2.305±1.493)mgC/(m.3h))比海台区((0.527±0.374)mgC/(m.3h))高近4倍。平均同化数为(1.22±1.14)mgC/(mgChla.h)。观测区细胞粒径>20μm的小型浮游生物对总叶绿素a浓度和初级生产力的贡献率分别为63.13%和65.16%,细胞粒径2.0～20μm的微型浮游生物和细胞粒径<2.0μm的微微型浮游生物对总叶绿素a和初级生产力的贡献率相差甚小,其对总叶绿素a浓度的贡献率分别为19.18%和17.69%,对总初级生产力的贡献率分别为20.11%和14.73%。

Investigations of chlorophyll a and primary productivity were carried out in the Chukchi Sea and its northern Chukchi Plateau during the 2^nd Chinese National Arctic Research Expedition in the summer of 2003. The results showed that the chlorophyll a concentrations were 0. 009 - 30. 390μg/dm^3 at the surveyed waters; the surface chlorophyll a concentrations were 0. 050-4. 644μg/dm^3 and the average value was （0. 875± 0. 981 ）μg/dm^3 in the surveyed area. In the continental shelf of the Chukchi Sea, the chlorophyll a concentrations at the depths 10m to bottom were higher than that in the surface water, and the concentrations were lower at the depths below 75m in the Chukchi Plateau, with average value of （0.015 ±0. 007 ）μg/dm^3 at the depth of 200m. The chlorophyll a concentrations decreased in 3 sequential samplings on the Section R, with column water average values of （2. 564 ± 1. 496 ）μg/dm^3, （ 1. 329± 0. 882 ） μg/dm^3 and （0. 965± 0. 623 ） μg/d^3, respectively. The potential primary productivity in the Chukehi Sea （ （2. 305 ± 1.493 ） mgC/（ m^3· h ） ） was higher than that in the Chukehi Plateau （ （0. 527 ±0.374） mgC/（m^3·h） ）. The assimilation number of photosynthesis was （1.22± 1.14）mgC/（mgChla. h） in the surveyed stations. The results of the size-fraetionated chlorophyll a and primary productivity showed that mieroplankton accounted for the majority of the total chlorophyll a （63. 13% ） and primary productivity （65. 16% ） in the Chukehi Sea. The contributions of the nanoplankton and pieoplankton to the total chlorophyll a and primary productivity were roughly the same; the average contribution rates for the total chlorophyll a were 19.18% and 17. 69%, respectively; and the average contribution rates for the total primary productivity were 20. 11% and 14. 73 % , respectively.