The phosphorus (P) concentration c1 in the surface layer of the Baltic proper in winter depends on the land-based P source LPS, and the ocean P source OPS, which are known. It also depends on the internal P source IPS from anoxic bottoms and the sum of internal and external P sinks TPsink, which are estimated in this paper. IPS is parameterized as fs·Aanox, where fs is the specific annual mass flux of P from anoxic sediments and Aanox is the area of anoxic bottoms, and TPsink is parameterized as c1·TRVF, where TRVF is the total removal volume flux. We use a time-dependent P budget model, and 47 years of observational data, and the method of least squares to determine the best estimates of the unknown parameters fs and TRVF. The result is TRVF = 3,000 km3 year−1 and fs = 1.22 tons P km−2 year−1. With these parameter values, the model gives a quite good description of the observed evolution of c1. The observed runaway evolution of c1, with increasing c1 since the 1980s although the land-based supply LPS has been halved, is well-described by the model. It is concluded that the internal P source IPS provides a positive feedback mechanism that has boosted and perpetuated the eutrophication of the Baltic proper and that IPS is the major driver of the Baltic Sea eutrophication since the late 1990s. It is suggested that measures to eliminate IPS should be included in the management strategy to reduce the eutrophication of the Baltic proper.

中文翻译：

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波罗的海的富营养化已被一个主要的内部磷源促进和延续

冬季波罗的海表层磷（P）浓度c1取决于陆源LPS和海洋P源OPS，这两个因素是已知的。它还取决于缺氧底部的内部P源IPS和本文估计的内部和外部P汇TPsink的总和。IPS 参数化为 fs·Aanox，其中 fs 是来自缺氧沉积物的特定年磷质量通量，Aanox 是缺氧底部的面积，TPsink 参数化为 c1·TRVF，其中 TRVF 是总去除体积通量。我们使用时间相关的 P 预算模型，以及 47 年的观测数据，以及最小二乘法来确定未知参数 fs 和 TRVF 的最佳估计值。结果是 TRVF = 3,000 km3 year−1 和 fs = 1.22 吨 P km−2 year−1。有了这些参数值，该模型很好地描述了观察到的 c1 演化。观察到的 c1 失控演变，自 1980 年代以来 c1 增加，尽管陆基供应 LPS 已减半，模型很好地描述了。得出的结论是，内部磷源 IPS 提供了一种正反馈机制，促进和延续了波罗的海本身的富营养化，并且 IPS 是自 1990 年代后期以来波罗的海富营养化的主要驱动因素。建议将消除 IPS 的措施纳入管理战略，以减少波罗的海地区的富营养化。得出的结论是，内部磷源 IPS 提供了一种正反馈机制，促进和延续了波罗的海本身的富营养化，并且 IPS 是自 1990 年代后期以来波罗的海富营养化的主要驱动因素。建议将消除 IPS 的措施纳入管理战略，以减少波罗的海地区的富营养化。得出的结论是，内部磷源 IPS 提供了一种正反馈机制，促进和延续了波罗的海本身的富营养化，并且 IPS 是自 1990 年代后期以来波罗的海富营养化的主要驱动因素。建议将消除 IPS 的措施纳入管理战略，以减少波罗的海地区的富营养化。