中文摘要：

利用1999,2003和2008年夏季（7—9月）三次中国北极科学考察数据资料,分析和讨论太平洋入流水营养盐的分布和楚科奇海关键生物地球化学过程对太平洋水化学性质的改造。结果表明,2003和2008年在白令海峡南部64.3°N纬向断面（BS断面）由于水团性质差异显著,营养盐呈西高、东低的分布趋势。2003年BS断面水柱上下分层明显,跃层以上水体营养盐浓度较低,可能是由生物泵作用和河流冲淡水稀释造成的。2008年BS断面东、西两侧水柱上下混合均匀,垂向营养盐浓度基本无变化;在海峡中部由于不同水团密度差异导致营养盐呈楔状分布,上层水体营养盐浓度较低。在BS断面2008年最高值大于2003年,这可能是BS断面西侧受到高营养盐的阿纳德尔流的影响,而在2003年考察BS断面未发现该水体的踪迹。太平洋水进入楚科奇海后由于浮游植物吸收利用和融冰水的稀释作用,沿170°W经向断面（C断面和R断面）的上层水体营养盐浓度明显低于跃层之下水体浓度。跃层之下水体受不同水团和Herald浅滩的影响,营养盐浓度在70°N以北海区浓度明显较高,但是仅从物理输送方面并不能找到太平洋水影响楚科奇海营养盐浓度的变化规律,这可能是有机质分解等化学过程有较大的年际变化。引入反映固氮和脱氮作用的参数N＊,并结合DIN与P和DIN与Si含量比值讨论楚科奇海脱氮作用对太平洋入流水化学性质的改造程度。较低的DIN与P含量比值和偏负的N＊数值表明,太平洋水流经白令海陆架时已经被脱氮作用改造而损失部分无机氮营养盐;进入楚科奇海后在底界面附近发生强烈的脱氮作用而损失更多的生物可利用氮,这将进一步加剧无机氮元素对北冰洋中心海盆浮游植物的限制。

英文摘要：

Nutrients were analyzed for Bering Strait and Chukchi shelf water samples collected during the 1999,2003 and 2008 arctic expedition of China.Concentrations of nutrients are the highest in the west part of the strait and decrease dramatically to the east part in summer.These spatial distributions of nutrients are depend on water masses（mixed layer,halocline waters,the Anadyr Current,the Alaskan coastal Current,Bering Shelf Current and Anadyr River water）,primary production and cyclone.Because of phytoplankton uptake and dilution effect of ice melt water,the concentration of nutrients in the mixed layer（10 m） is lower than the deep layer of the meridian section along 170°W.Below 10 m,nutrients concentrations are higher in the north of 70°N than the southern part of Chukchi Sea because of the Herald shoal and different water mass.Besides physical transport,the variation of organic matter re-mineralization may be another important factor for the nutrients distribution patterns.parameter N＊{N＊=[（c（DIN）-16c（P）＋2.98]×0.87} was applied to discussing the loss of fixed nitrogen to N2 via denitrification or anammox processes.The values of N＊ in the Bering Strait region are less negative than that in waters of Chukchi Sea,suggested that the Pacific inflow transforms fixed nitrogen to N2 on the Bering Sea shelf.From the negative N＊ value and lower concentration ratio of（nitrate plus nitrite plus ammonium） to phosphate in th Chukchi Sea that it is inferre the loss of fixed nitrogen in the water-sediment interface will increase nitrogen limitation to the Arctic Ocean phytoplankton growth.