Dissolved oxygen of discrete water column samples at selected depths collected aboard Palmer LTER annual cruises off the coast of the Western Antarctic Peninsula, 1993 - 2012.

Oxygen is produced by phytoplankton photosynthesis and consumed by respiration of phytoplankton, zooplankton and bacteria. Oxygen also enters and exits the ocean via physical exchange with the atmosphere. Oxygen concentrations in the surface ocean may be supersaturated by photosynthesis and turbulence enhancing air-sea exchange via bubble injection; or undersaturated due to excess respiration. In cases where exchange with the atmosphere is limited, and/or respiration exceeds photosynthesis, oxygen concentration can be reduced to very low levels (hypoxia) or entirely depleted (anoxia). This is uncommon in cold Antarctic Seas where respiration is depressed and oxygen solubility is enhanced by low temperature. Different water masses have characteristic oxygen concentrations which serve as tracers for diagnosing physical mixing and advection. Dissolved oxygen was analyzed by Winkler Titration (see Methods) in CTD-Rosette bottle samples at all depths sampled until 2012. This measurement was discontinued in 2013. The CTD has duplicate oxygen electrodes that provide continuous vertical profiles of oxygen concentration at all depths on all casts. The vessel also has continuous underway, Optode determination of dissolved oxygen in the surface (ship's intake at 6 meters depth) on all cruises. Finally we now routinely measure net community production by Equilibrator Inlet Mass Spectroscopy (EIMS) on LTER cruises

浮游植物（phytoplankton）通过光合作用产生氧气，而氧气会被浮游植物、浮游动物（zooplankton）与细菌的呼吸作用消耗。此外，氧气还可通过与大气的物理交换过程进入海洋或从海洋逸出。
表层海洋的溶解氧浓度可能因光合作用与湍流作用（后者通过气泡注入增强海-气交换）而过饱和；也可能因呼吸作用过剩而处于不饱和状态。当与大气的交换受到限制，或呼吸作用强度超过光合作用时，溶解氧浓度可降至极低水平（低氧(hypoxia)），甚至完全耗尽（无氧(anoxia)）。这种情况在寒冷的南极海域较为罕见——该海域呼吸作用受到抑制，且低温提升了氧气的溶解度。
不同水团具有特征性的溶解氧浓度，可作为示踪剂用于诊断物理混合与平流输送过程。直至2012年，所有采水深度的CTD-Rosette采水器样品均通过温克勒滴定法（Winkler Titration，参见方法部分）完成了溶解氧测定。该检测项目于2013年终止。
该CTD系统配备冗余溶解氧电极，可在所有观测站位获取全水深的溶解氧浓度连续垂直剖面。该科考船还在所有航次中搭载了连续走航式Optode传感器，对6米船载取水深度处的表层海水溶解氧进行测定。最后，我们目前在长期生态研究（LTER）航次中，常规通过平衡器入口质谱法（Equilibrator Inlet Mass Spectroscopy，EIMS）测定群落净生产力。