Bouillon S, Dehairs F
Department of Analytical Chemistry, Free University of Brussels.
Isotopes Environ Health Stud. 2000;36(3):273-84. doi: 10.1080/10256010008036387.
In estuarine ecosystems, large spatial and seasonal variations in delta13C values of primary producers can occur, and knowledge of these variations may be crucial when interpreting stable isotope data of higher trophic levels. Obtaining clean phytoplankton samples for isotope analysis is usually impossible in such systems, and analysis of total suspended matter is not a simple proxy for phytoplankton delta13C variations. Based on a few simple assumptions regarding the C and N content of the two end-members (terrestrial detritus and phytoplankton) and the delta13C of the terrestrial component, we here present a simple model to estimate the phytoplankton delta13C variations using an existing dataset on the delta13C and elemental (C:N) composition of suspended organic matter from an estuarine mangrove ecosystem in southeast India. These variations are related to the monthly rainfall pattern during the sampling period. It is stressed that this method estimates approximate phytoplankton delta13C values, which should not be used in e.g., mixing models. However, we propose that in cases where sufficiently large datasets are available, the described procedure could provide a valuable method to semi-quantitatively estimate the seasonal or spatial variations of the phytoplankton delta13C signal.
在河口生态系统中，初级生产者的δ13C值可能会出现较大的空间和季节变化，而在解释较高营养级的稳定同位素数据时，了解这些变化可能至关重要。在这样的系统中，通常无法获得用于同位素分析的纯净浮游植物样本，并且对总悬浮物的分析并非是浮游植物δ13C变化的简单替代指标。基于关于两个端元（陆地碎屑和浮游植物）的碳和氮含量以及陆地组分的δ13C的一些简单假设，我们在此提出一个简单模型，利用来自印度东南部河口红树林生态系统的悬浮有机物的δ13C和元素（碳：氮）组成的现有数据集来估算浮游植物的δ13C变化。这些变化与采样期间的月降雨模式有关。需要强调的是，该方法估算的是浮游植物δ13C的近似值，例如不应在混合模型中使用。然而，我们建议在有足够大的数据集可用的情况下，所描述的程序可为半定量估算浮游植物δ13C信号的季节或空间变化提供一种有价值的方法。
