Final answer:
The concentration of dissolved organic matter (DOC) in the open surface ocean is generally greater than that of particulate organic matter (POC), with DOC being a significant component of marine chemistry and affecting the ecosystem's health. Option b is the correct answer.
Step-by-step explanation:
Understanding the differences between dissolved organic matter (DOC) and particulate organic matter (POC) in the open surface ocean is essential for marine biology studies. DOC consists mostly of large molecules of decaying organic matter, which can affect the penetration of sunlight through the water column. On the other hand, POC consists of small organic particles suspended in the water. Generally, much of the organic carbon found in seawater is in the form of DOC, with a very small percentage being POC.
Studies show that the total organic carbon content can range between 0.5 mg/L in deep water to about 1.5 mg/L near the surface. However, despite the low abundance of organic matter in seawater, it plays a significant role in ocean chemistry and life. For instance, DOC and POC can influence the amount of oxygen in the water. The presence of too much decaying organic matter, which is often related to pollutants like sewage, can lead to high biochemical oxygen demand (BOD) and deplete the oxygen necessary for aquatic life. Conversely, an equilibrium in DOC and POC is crucial for maintaining a healthy marine ecosystem.
Given this information, when comparing the concentrations of DOC and POC in the open surface ocean, it is generally agreed that the concentration of dissolved organic matter (DOC) is greater than that of particulate organic matter (POC). Therefore, the correct answer is B. [DOC] is greater than [POC].