马里亚纳海沟“挑战者深渊”营养盐的垂直分布特征

2015年12月在马里亚纳海沟"挑战者深渊"进行了定点样品采集,对温度、盐度、溶解氧、pH等环境参数进行了分析,讨论了营养盐的垂直分布特征、各形态营养盐结构特征及影响因素。研究发现,溶解氧在表层具有最大值,在1000 m左右出现极小值,而在8700 m深度具有较高溶解氧值(5.79 mg·L^-1),这可能与富氧水团的存在有关。硝酸盐表层含量较低,在1000和5367 m处出现双峰值。在表层水体中,溶解有机氮、磷是溶解总氮、溶解总磷的主要存在形式,表层以深,溶解无机氮、磷逐渐占据主导地位。磷酸盐表层含量最低,在1000 m处达到最大值,之后随着深度的增加浓度逐渐降低;硅酸盐在表层含量较低,在约4000 m处有最大值161.65μmol·L^-1,在4000 m以深,硅酸盐仍维持较高浓度。结果表明马里亚纳海沟"挑战者深渊"的溶解氧、pH及营养盐的垂直分布特征与大洋环流、海沟形态以及生物活动密切相关。

The Vertical Distribution of Nutrients in the Challenge Deep of the Mariana Trench

Based on the samples collected in the Mariana trench,the authors analyzed the vertical distribution of nutrients,temperature,salinity,dissolved oxygen and pH.Moreover,the structure and influence factor of nutrients were discussed.The results show that the maximum value of dissolved oxygen in Mariana trench was in the surface layer and the minimum value was at 1000 m in depth.However,there was a high dissolved oxygen value(5.79 mg/L^-1)at 8700 m in depth,which may be related to the existence of oxygen-enriched water masses.The nitrate concentration in surface layer was low,and there are two peaks at 1000 and 5367 m.Dissolved organic nitrogen is the main form of dissolved total nitrogen in surface seawater.From surface to bottom,dissolved inorganic nitrogen gradually became the dominant form of dissolved total nitrogen.In terms of vertical distribution,the concentration of phosphate was the lowest at the surface layer.Maximum value was at 1000 m in depth(2.84μmol·L^-1).Below 1000 m in depth,concentration gradually decreased with depth.Silicate was depleted at surface layer.Maximum value(161.65μmol·L^-1)was at approximately 4000 m.At the maximum depth,silicate concentration was still high.The results indicate that the vertical distribution characteristics of dissolved oxygen,pH and nutrients in the Mariana trench are closely related to ocean circulation,trench morphology and biological activities.