Phosphorus Release from Sediments in Aquatic Ecosystems: A Cross-System Study

湖泊沉积物通过保留或释放溶解的磷的能力，在控制磷向水体输送方面发挥了关键作用。在海洋中，只需知道发生了多少分解，就可以相对准确地预测磷的释放。因此，在海洋系统中，分解后的因素(吸附、矿物形成、微生物固定)与分解相比是次要的。另一方面，在淡水中，这些分解后的因素是重要的，使得沉积物中磷的释放更加难以预测。尽管几十年来对淡水中沉积物磷的释放进行了研究，并在实验室中列出了可能影响这种释放的因素，但基本上不知道这些因素中哪些在自然系统中实际上是重要的；因此，预测磷释放的能力有限。科尔、卡拉科和利肯斯建议在非常广泛的地理范围内研究硬水和软水湖泊中磷释放的控制。他们将使用一种直接的、现场的、从海洋学修改而来的地球化学方法，从经验上研究大量湖泊类型的磷释放，并从机械上研究六个湖泊中磷的释放，这些湖泊的磷释放响应截然不同。初步结果表明：1)与标准的湖沼学教义相反，有氧和缺氧条件对系统间沉积物磷释放的巨大自然变化的解释很少；2)这种变化可以用系统中的硫含量来解释。科尔、卡拉科和利肯斯都是非常多产和创新的研究人员，他们提供了一种独特的方法来研究营养通量。这项研究得到了极好的制度支持。研究人员提出了一种可行的机制来解释淡水系统中的磷通量。这项研究中提出的测试应该会带来重要的信息，这些信息将影响水管理政策。

Lake sediments, by their ability to retain or release dissolved phosphorus, play a critical role in controlling p- lading to the water column. In the ocean P release can be predicted relatively accurately simply from a knowledge of how much decomposition occurred. Thus, in marine systems post- decompositional factors (sorption, mineral formation, microbial immobilization) are of minor importance in comparison to decomposition. In freshwaters, on the other hand, these post- decompositional factors are of major importance making sediment P release much more difficult to predict. Despite decades of research on sediment P release in freshwaters, and lists of factors that might influence this release in the laboratory, there is essentially no knowledge as to which of these factors are actually important in natural systems; consequently there is limited ability to predict P release. Cole, Caraco, and Likens propose to investigate the controls of P release in both hard and soft-water lakes over a very broad geographic range. They will use a straightforward, in situ, geochemical approach modified from oceanography, to investigate P release both empirically across a large number and range of lake types, and mechanistically in a of suite six lakes that differ dramatically in their P release responses. Preliminary results suggest that: 1) Contrary to standard limnological dogma, oxic versus anoxic conditions explains very little of the enormous natural variation in sediment P release among systems; 2) this variation is best explained by the sulfur content of the system. Cole, Caraco and Likens are very productive and innovative researchers who have provided a unique way to investigate nutrient fluxes. The Institutional support for this research is excellent. The investigators propose a feasible mechanism to explain phosphorus fluxes in freshwater systems. The tests proposed in this research should lead to important information that will impact water management policies.