Final answer:
Non-conservative nutrients in seawater are those whose ratios do not remain constant due to biological uptake and environmental variability, such as iron, molybdenum, and various other trace elements that are utilized differently by marine organisms.
Step-by-step explanation:
The nutrients in seawater that do not maintain constant ratios to one another and are considered non-conservative are typically the ones utilized by marine organisms and can include elements such as iron, molybdenum, barium, cobalt, copper, lead, nickel, silver, and zinc. Due to biological activities, these nutrients can vary in concentration. For example, phytoplankton blooms can deplete nutrients like nitrogen and phosphorus, causing their ratios to change depending on biological demand and other environmental factors. The cycling of these nutrients is crucial for maintaining the health of marine ecosystems, and processes like ocean upwelling can bring nutrients from the deep sea back to the surface, thus replenishing the supply for phytoplankton and other organisms.
Other examples of such variability can be found in the concentrations of organic matter and the specific case of urea and trimethylamine oxide (TMAO) in the blood of sharks, which is a unique adaptation not reflected in the general composition of seawater. The proportion of essential elements required by marine life forms can differ significantly from their relative abundance in the surrounding sea, further illustrating the non-conservative nature of certain nutrients in the aquatic environment.