Introduction: Measuring the chemical oxygen demand (COD) is a way of determining the organic matter in water based on its oxidisibility by bichromate. The presence of organic matter in sea water is one of the factors that determines the productivity of the oceans: whether this organic matter will be absorbed directly or must first be transformed into nutritive substances by bacteria. This beneficial action also has its limits. On the one hand, consumption of organic matter remains limited; when it exceeds a certain rate, there is no longer any increase in productivity. On the other hand, the excess organic matter deteriorates by consuming the dissolved oxygen and thus competes with marine life. In extreme cases, this excess can cause the eutrophication of... |