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-0525843Rates主要生产，社区呼吸和净社区生产是至关重要的基础，可以理解从大气到深海的碳的生物泵。 然而，瓶中孵化方法的固有缺陷，尤其是瓶孵化的时间尺度与生物群落对水柱中不断变化的状况的反应之间的不匹配，这加剧了持续的辩论，是海洋净自养生的少亲营养区域是否是净自养生的还是多营养的。 由于体外技术可能会错过高生产率的发作，因此瓶中孵化方法中的固有潜在偏差是对异性萎缩的。 一种新开发的方法，氧同位素方法（OIM）具有不需要瓶子孵化的优点，因此对14C和O2瓶孵育方法固有的体外与原位不确定性不敏感，传统上用于估计海洋中的初级生产和净社区生产。其次，OIM产生的速率在混合层中O2的10-20天停留时间内整合，这意味着与孵化方法相比，OIM错过了主要生产事件的可能性要小得多。 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. 基于研究者在Aloha站的初始氧同位素和O2/AR测量值，通过氧同位素方法测量的原位总生产平均是基于14C的初级生产估计值的两倍以上。 因此，预计每年一年的原位主要产量和Aloha的净社区生产率将超过基本生产和净社区生产的体外率，并表明净自身萎缩。如果是这样，这将是对假设的积极检验。与OIM测量一起，PI将比较由14C瓶孵育，快速重复速率荧光测量测量结果确定的独立的原始生产和净社区生产率与独立的主要生产估计值初级生产测量的技术。 关于更广泛的影响，拟议的研究将改善对海洋生物泵的估计，如果应响应全球变暖，它将影响大气二氧化碳的积累速度。拟议的研究将增加一个大量的数据集，包括亚热带N. Pacific的初级生产和净社区生产的每月估计值，该数据可以被广泛的海洋学界使用，并与Aloha测得的14C主要生产的十年数据集相比。该项目将有本科生和研究生参与。通过同位素样品制备系统的自动化，将增强设备基础设施。