Organic Matter Cycling
Organic Matter Cycling
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有机物循环
DOI：
10.1093/oso/9780195160826.003.0017
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发表时间：
2006
期刊：
影响因子：
--
通讯作者：
T. Bianchi
中科院分区：
文献类型：
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作者：
T. Bianchi
本章将讨论控制有机质产生和转化的一般过程，以及一些关键生物元素(如C、N、P、S)的一些相关化学计量变化。化学计量学被定义为化学反应的质量平衡，因为它们与确定的比例定律和质量守恒有关(Sterner和Elser，2002)。例如，如果我们检查浮游植物中C、N和P的平均原子比率，我们会发现大多数海洋物种的比率相对一致，为106：16：1。这可能是自然生态系统中应用化学计量学原理的最好例子，并且源自Alfred C.Redfield(1890-1983)的经典工作(Redfield，1958；Redfield等人，1963)。更具体地说，Redfield比较了海水中溶解营养物的C、N和P的比率与悬浮海洋颗粒物(Seston)(主要是浮游植物)的比率，发现了斜率相等的直线(图8.1；Redfield等人，1963年)。这种关系表明，海洋生物群对决定世界海洋的化学成分至关重要，这显然是将化学海洋学和生物海洋学联系起来的最重要的历史发现之一(Falkowski，2000)。此外，利用改进的分析技术，用最近的数据进一步验证了Redfield比率(Karl等人，1993；Hoppema和Goeyens，1999)。其他工作表明，在淡水和开阔海洋的海洋梯度上存在可预测的红场比偏差(图8.2；唐宁，1997年)。例如，河口的氮磷比通常被证明低于和/或高于预计的红场比，这分别是由于反硝化作用和人为营养丰富过程。向河口系统输入维管植物有机质(如红树林、盐沼、海草)是造成C：N：P偏离Redfield比率的另一个问题。已证明维管植物偏离这一比率的部分原因是，与藻类相比，C和N的含量相对较高，这是因为分别含有更多的结构支持分子(例如纤维素、木质素)和防御抗草食(次要)化合物(例如单宁)(Vitousek等人，1988年)。
In this chapter the general processes involved in controlling production and transformation of organic matter will be discussed as well as some of the associated stoichiometric changes of a few key biological elements (eg, C, N, P, S). Stoichiometry is defined as the mass balance of chemical reactions as they relate to the law of definite proportions and conservation of mass (Sterner and Elser, 2002). For example, if we examine the average atomic ratios of C, N, and P in phytoplankton we see a relatively consistent ratio of 106: 16: 1 in most marine species. This is perhaps the best example of applied stoichiometric principles in natural ecosystems and is derived from the classic work of Alfred C. Redfield (1890–1983)(Redfield, 1958; Redfield et al., 1963). More specifically, Redfield compared the ratios of C, N, and P of dissolved nutrients in marine waters to that of suspended marine particulate matter (seston)(essentially phytoplankton) and found straight lines with equal slopes (figure 8.1; Redfield et al., 1963). This relationship suggested that marine biota were critical in determining the chemistry of the world ocean, clearly one of the most important historical findings linking chemical and biological oceanography (Falkowski, 2000). Moreover, the Redfield ratio has been further validated with recent data using improved analytical techniques (Karl et al., 1993; Hoppema and Goeyens, 1999). Other work has shown that there are predictable deviations from the Redfield ratio across a freshwater to open ocean marine gradient (figure 8.2; Downing, 1997). For example, N-to-P ratios in estuaries have commonly been shown to be lower and/or higher than the predicted Redfield ratio because of denitrification and anthropogenic nutrient enrichment processes, respectively. Inputs of vascular plant organic matter (eg, mangroves, salt marshes, seagrasses) to estuarine systems presents another problem in causing deviations of C: N: P from the Redfield ratio. Vascular plants have been shown to deviate from this ratio in part because of relatively high amounts of C and N compared to algae due to a higher abundance of structural support molecules (eg, cellulose, lignin) and defense antiherbivory (secondary) compounds (eg, tannins), respectively (Vitousek et al., 1988).