< p >海洋不饱和或钠氯。事实上,海洋的化学组成仍然相当恒定数亿年。然而河流和其他来源不断把钠、氯和其他溶解元素和化合物的海洋。这意味着一些过程必须移除组成元素的存在或多或少相同的速度,世界的河流和其他来源供应这些成分。< / p > < p >确实地球的河流给海洋带来更多的钙和碳酸根离子比钠离子和氯离子。溶解的二氧化碳从大气中提供了另一个碳酸根离子的来源。然而海洋确实大大减少钙和碳酸盐岩与供应从河流。这是为什么?< / p > < p >海洋远比是咸供应海洋的河流。这主要是由于蒸发。即便如此,钠和氯只是一小部分在世界海洋的饱和水平。 This is not the case for calcium and carbonate. Carbonates in general have a low saturation level, and amongst common cations, calcium carbonate has a very low saturation level. Calcium carbonate is typically at or near the saturation level in the oceans, and oftentimes above it, particularly near the surface. This makes it very easy for calcium carbonate to come out of solution. Because calcium and carbonate are at or above the saturation level, just about anything can cause calcium carbonate to form. The key "just about anything" process that causes calcium and carbonate to come out of solution is life.
This means that calcium and carbonate have a rather low residence time in the oceans. The processes that remove sodium and chlorine are much, much slower. The slowness by which sodium and chlorine are removed versus the rapidity by which calcium and carbonate are removed are why the oceans are "upside down" compared to rivers with regard to calcium, carbonate, sodium, and chlorine.