Particulate organic carbon : natural radionuclide ratios in zooplankton and their freshly produced fecal pellets from the NW Mediterranean (MedFlux 2005)
Particulate organic carbon : natural radionuclide ratios in zooplankton and their freshly produced fecal pellets from the NW Mediterranean (MedFlux 2005)
复制标题
颗粒有机碳：浮游动物及其新鲜产生的地中海西北部粪便颗粒中的天然放射性核素比率（MedFlux 2005）
DOI：
10.4319/lo.2007.52.3.0966
复制
发表时间：
2007
影响因子：
4.5
通讯作者：
J. Miquel
中科院分区：
文献类型：
--
作者：
Alessia M Rodriguez y Baena;S. Fowler;J. Miquel
为了辨别对颗粒有机碳（POC）：天然放射性核素（RN）比率变异性的控制，以提高基于水体放射性核素的碳通量估计的准确性，对来自不同类群（樽海鞘、磷虾、桡足类、翼足类动物），以及春季从地中海西北部收集的浮游动物新鲜产生的粪便中。浮游动物中 234Th 和 210Po 的 POC:RN 比率分别在 120 和 11,600 之间，以及 89 和 9,200 µmol dpm−1 之间。在粪便颗粒中，234Th 的 POC:RN 比率低 1 到 3 个数量级，210Po 低 3 倍到 30 倍；唯一的例外是常壳体翼足类动物，其颗粒中的 POC：210Po 比率高于其整个身体中的 POC：210Po 比率。 POC: 234Th (p < 0.0006) 的幂关系和 POC: 210Po 的饱和指数方程（POC: 210Po 比率恒定在 70 µm 以上；p < 0.004）最好地描述了 POC:RN 比率随生物体大小的显着增加，这表明观察到的趋势很可能是 234Th 的表面吸附过程和 210Po 的食物链生物累积过程造成的。观察结果进一步支持了这一推论，即对于 >33 µm 尺寸类别，210Po 比活度与表面积：体积比呈负相关，而 234Th 与其呈正相关（分别为 p < 0.004 和 p < 0.001）。 POC:RN 比率在不同物种之间差异很大，并且在粪便颗粒类型之间差异较小，这很可能是由于浮游动物摄食策略的差异造成的。从陷阱样本中部分去除大多数浮游动物“游动者”不太可能混淆 234Th 通量的评估；然而，它可能会对 210Po 通量以及 POC:RN 比率的类似测量产生很大的偏差。
To discern controls on particulate organic carbon (POC) : natural radionuclide (RN) ratio variability in order to enhance the accuracy of water column radionuclide‐based carbon flux estimates, 234Th, 210Po, and POC were analyzed in seven size classes of mixed micro‐ and mesoplankton (1‐1,500‐µm size range), in larger zooplankton from different taxa (salps, euphausiids, copepods, pteropods), and in freshly produced feces from zooplankton collected during spring in the NW Mediterranean. POC:RN ratios in zooplankton ranged between 120 and 11,600 and between 89 and 9,200 µmol dpm−1 for 234Th and 210Po, respectively. In fecal pellets, POC:RN ratios were one to three orders of magnitude lower for 234Th and 3‐fold to 30‐fold lower for 210Po; the only exception was euthecosome pteropods, which had a higher POC: 210Po ratio in their pellets than in their whole bodies. Significant increases in POC:RN ratios with organism size were best described by a power relationship for POC: 234Th (p < 0.0006) and a saturation exponential equation for POC: 210Po (with a constant POC: 210Po ratio above 70 µm; p < 0.004), suggesting that the observed trend most likely results from surface adsorption processes for 234Th and food chain bioaccumulation for 210Po. This inference is further supported by the observation that, for the >33‐µm size classes, 210Po specific activity correlates negatively with the surface : volume ratio, while 234Th correlates positively with it (p < 0.004 and p < 0.001, respectively). POC:RN ratios vary greatly among species and to a lesser extent among fecal pellet types, most probably due to differences in zooplankton feeding strategies. Partial removal of most zooplankton “wimmers” from trap samples would not likely confound assessment of 234Th flux; however, it could considerably bias similar measurements of 210Po flux as well as those of POC:RN ratios.