In-situ Rates of Gross Primary Production, Respiration, and Net Community Production in the Subtropical N. Pacific

北太平洋副热带地区初级生产力、呼吸和净群落生产力的原位速率

• 批准号: 0525843
• 负责人: Paul Quay
• 金额: $ 47.61万
• 依托单位: University of Washington
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-09-01 至 2009-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0525843&HistoricalAwards=false
• 关键词: situ; Rates; Gross; Primary; Production

ABSTRACTOCE-0525843Rates of primary production, community respiration, and net community production in the ocean are crucial underpinnings to understand the biological pump of carbon from the atmosphere to the deep sea. However, the inherent deficiencies with bottle incubation methods, especially the mismatch between the timescales of bottle incubations and the response of biological communities to changing conditions in the water column, has fueled an ongoing debate whether oligotrophic regions of the ocean are net autotrophic or heterotrophic. Since the in vitro techniques can miss episodes of high productivity, the inherent potential bias in bottle incubation methods is towards heterotrophy. A newly developed method, the oxygen isotope method (OIM) has the advantage of not requiring bottle incubations and thus is not sensitive to the in vitro versus in situ uncertainty inherent to the 14C and O2 bottle incubation methods traditionally used to estimate primary production and net community production in the ocean. Second, the OIM yields rates that integrate over the 10-20 day residence time of O2 in the mixed layer which means that the OIM is much less likely to miss primary production events compared to incubation methods. In this study, a researcher from the University of Washington will use the OIM to improve our understanding of the temporal variability in primary production and net community production, and test the hypothesis of oceanic heterotrophy by estimating monthly rates of in situ gross primary production, community respiration, and net community production off Hawaii at station ALOHA using measurements of the natural abundance of oxygen isotopes and the ratio of dissolved O2/Ar gases. Based on the investigator's initial oxygen isotope and O2/Ar measurements at station ALOHA, in situ gross primary production measured by the oxygen isotope method was on average more than twice the 14C-based estimates of primary production. Annually integrated in situ gross primary production and net community production rates at ALOHA are therefore expected to exceed the in vitro rates of gross primary production and net community production and indicate net autotrophy. If so, this would be positive test of the hypothesis. Along with the OIM measurements, the PI will compare the OIM-based rates of gross primary production and net community production to independent primary production estimates determined from 14C bottle incubations, Fast Repetition Rate Fluorometry measurements, a bio-optical model, a continuous record of surface layer in situ O2 measured by a moored O2 sensor and satellite-based estimates of variability in chlorophyll and primary production to provide a complete intercalibration with extant techniques for primary production measurements. Concerning the broader impacts, the proposed research will improve estimates of the ocean's biological pump, which if it should change in response to global warming, would affect the rate of atmospheric CO2 build-up. The proposed research will add a significant dataset of monthly estimates of primary production and net community production in the subtropical N. Pacific that can be used by the broad oceanographic community and compared to the decade-long dataset of 14C-primary production measured at ALOHA. There will be both undergraduate and graduate student involvement in the project. Equipment infrastructure will be enhanced through the automation of the isotope sample preparation system.

ABSTRACTOCE-0525843海洋中初级生产力、群落呼吸和净群落生产的速率是了解碳从大气到深海的生物泵的重要基础。 然而，瓶子孵化方法的固有缺陷，特别是瓶子孵化的时间尺度与生物群落对水体条件变化的响应之间的不匹配，引发了关于海洋寡营养区域是净自养还是异养的持续争论。 由于体外技术可能会错过高生产力的时期，因此瓶子孵化方法固有的潜在偏差是异养。 氧同位素法 (OIM) 是一种新开发的方法，其优点是不需要瓶培养，因此对传统上用于估计初级产量和净产量的 14C 和 O2 瓶培养方法固有的体外与原位不确定性不敏感。海洋中的社区生产。其次，OIM 的产率综合了 O2 在混合层中 10-20 天的停留时间，这意味着与孵化方法相比，OIM 错过初级生产事件的可能性要小得多。在这项研究中，华盛顿大学的研究人员将使用 OIM 来提高我们对初级生产和净群落生产的时间变异性的理解，并通过估计原地总初级生产、群落净生产的月率来检验海洋异养的假设。使用氧同位素自然丰度和溶解的 O2/Ar 气体比率的测量，在夏威夷附近的 ALOHA 站进行呼吸作用和净群落生产。 根据调查人员在 ALOHA 站的初始氧同位素和 O2/Ar 测量，通过氧同位素方法测量的原位总初级生产力平均是基于 14C 的初级生产力估计值的两倍多。 因此，ALOHA 的年度综合原地总初级生产力和净群落生产力预计将超过体外总初级生产力和净群落生产力，并表明净自养。如果是这样，这将是对假设的积极检验。除了 OIM 测量之外，PI 还将基于 OIM 的总初级生产力和净群落产量与通过 14C 瓶孵化、快速重复率荧光测量、生物光学模型、连续记录确定的独立初级生产力估计值进行比较。通过系留 O2 传感器测量表层原位 O2，并基于卫星对叶绿素和初级生产的变异性进行估计，以提供与初级生产测量的现有技术的完整相互校准。 就更广泛的影响而言，拟议的研究将改进对海洋生物泵的估计，如果海洋生物泵因全球变暖而改变，将影响大气中二氧化碳的积累速度。拟议的研究将添加一个重要的数据集，其中包括北太平洋副热带初级生产和群落净生产的月度估计值，可供广泛的海洋学界使用，并与 ALOHA 测量的长达十年的 14C 初级生产数据集进行比较。本科生和研究生都会参与该项目。通过同位素样品制备系统的自动化，将增强设备基础设施。