Organic matter content, oxygen content, inorganic mineral ion content
The first is the organic matter content. The organic matter content here mainly discusses the biological energy in water, that is, the organic matter content of living organisms. First of all, the organic content of specially made tiny organisms, such as plankton, microorganisms and algae, is generally the starting point of the food chain. Comparatively speaking, the organic content of lake water is higher than that of seawater on average, because seawater has obvious peaks and valleys due to the phenomenon of cluster biological explosion caused by ocean currents, while the water area of upper seawater is larger than that of lake water, with an average of slightly smaller.
Then compare the oxygen content. Generally speaking, the oxygen content of water is determined by photosynthetic organisms. Generally speaking, the amount of dissolved oxygen in water is constant under natural conditions. Therefore, although the contact area between seawater and air is large, the oxygen content of seawater and lake water should be similar. Of course, there are other factors. Because of the cluster explosion of algae and plankton in seawater, there will be a peak-valley oxygen fluctuation curve under the average oxygen content, so the oxygen content of seawater will eventually be greater than that of lake water. In addition, from the common sense, the rapid airflow on the sea surface is conducive to the use of ocean currents to supplement the oxygen content of seawater, so seawater is slightly better in this respect.
Finally, the ion content of inorganic minerals: this is related to the degree of nutrition and needs to be divided into two categories, one is related to elements such as nitrogen, phosphorus and potassium, and the other is trace elements. As we all know, if lakes are eutrophic, it is difficult to clean up pollution. However, the water area of seawater is very large, which can be well adjusted naturally. Therefore, in the content of the first kind of N, P and K elements, lakes are dominant, which is related to the fact that lakes are close to human life and have certain connections with human production and life (most of N, P and K are obtained from the sediments brought by the confluence of rivers and lakes, but there are also many sediments). Seawater is dominated by trace elements, because the seabed can contact more rock formations. (Although some lakes are the same as groundwater, they can contain good trace elements, but they are only individuals and cannot be considered as normal. )
After the above analysis, to sum up, the nutritional level of seawater is higher.