New and Regenerated Production in the Southern Ocean: Ross Sea Studies

该研究项目是美国“全球海洋通量联合研究”（JGOFS）南大洋项目的一部分，旨在：(1)更好地了解南大洋有机和无机碳通量，(2)确定调节这些通量的大小和变化的物理、生态和生物地球化学因素和过程，以及(3)将这些通量置于当代全球碳循环的背景下。罗斯海广阔的大陆架的特点是相对较高的生物量和大量的浮游植物在南部春夏繁殖。作为美国JGOFS南大洋碳和生物通量综合调查计划的一部分，该地区已被指定为进行强化过程研究的区域。作为这项工作的一部分，本研究的目的是评估南极洲生产生长季节（春季、夏季、秋季）罗斯海大陆架地区新生产和再生生产的速度。本研究的总体目标是对这一动态系统中浮游生物组合的氮营养进行准确和定量的估计，并了解控制初级生产的幅度和变异性以及来自磷光带（即出口生产）的生物物质垂直通量的因素。将进行一套核心测量，以估计相关空间和时间尺度上的新产量和再生产量。罗斯海的新产量被假设为生态系统发展演变的一个功能，因此受到以下因素的调节：水柱的水动力特性（即冰融化的垂直稳定性）、宏量营养素（铵和尿素）的相互作用以及微量营养素铁的可用性。核心测量包括使用15n示踪技术确定四种氮底物（硝酸盐，亚硝酸盐，铵和尿素）的吸收率；在沿冰缘（边缘冰带）的横断面分布的站点，穿过大陆架、斜坡并进入公海；在7个深度测量，从100%到1%的表面辐照度；在早上，中午和晚上。同位素稀释程度将在氮吸收实验中量化，以更准确地确定吸收速率，并估计微异养氮再生速率。除了核心测量之外，额外的实验将回答有关系统的具体问题，并将改进我们对新生产和再生生产的估计。

95-30732 Bronk This research project is part of the US Joint Global Ocean Flux Study (JGOFS) Southern Ocean Program aimed at (1) a better understanding of the fluxes of carbon, both organic and inorganic, in the Southern Ocean, (2) identifying the physical, ecological and biogeochemical factors and processes which regulate the magnitude and variability of these fluxes, and (3) placing these fluxes into the context of the contemporary global carbon cycle. The broad continental shelf of the Ross Sea is characterized by relatively high biomass with large phytoplankton blooms in the austral spring-summer. This region has been designated as an area for intensive process studies as part of the U.S. JGOFS comprehensive investigative program of carbon and biogenic fluxes in the Southern Ocean. As part of that effort, this study is designed to assess the rates of new and regenerated production in the Ross Sea continental shelf regime during the productive growing season in Antarctica (spring, summer, autumn). The overall objectives of this study are to obtain accurate and quantitative estimates of the nitrogenous nutrition of the planktonic assemblages in this dynamic system, and to understand the factors which control the magnitude and variability of primary production and the vertical flux of biogenic material from the euphotic zone (i.e. export production). A suite of core measurements will be made to estimate new and regenerated production over relevant spatial and temporal scales. New production in the Ross Sea is hypothesized as a function of the evolution of the ecosystems' development and thus regulated by: the hydrodynamic properties of the water column (i.e. vertical stability from ice melt), the interaction of macronutrients (ammonium and urea), and the availability of the micronutrient iron. Core measurements include determining the uptake rates of four nitrogen substrates (nitrate, nitrite, ammonium, and urea) using the 15N-tracer technique; at stations distributed along transects from the ice-edge (marginal ice zone), across the shelf, slope, and into the open ocean; with measurements at seven depths ranging from 100% to 1% of surface irradiance; during morning, mid-day and night. The degree of isotopic dilution will be quantified during nitrogen uptake experiments to more accurately determine rates of uptake, and to estimate rates of microheterotrophic nitrogen regeneration. In addition to the core measurements additional experiments will answer specific questions about the system, and will refine our estimates of new and regenerated production.