Final answer:
Geological processes, sources of water, and temperature are primary factors affecting isotope concentrations in water. These are influenced by the local geology, water sources, and temperature-related changes in solubility. Human activity through pollution and biological activity also play a role.
Step-by-step explanation:
The factors that affect the concentrations of isotopes in water in different geographic areas are primarily geological processes and sources, as well as temperature. Geological processes can include the composition of surrounding rocks and the presence of underwater springs that contribute certain isotopes to the water. The sources of water, such as glacial melt or precipitation, also influence isotopic concentrations. Temperatures influence solubility, with gas solubility decreasing as temperature increases. This is significant because it affects the dissolved oxygen levels in water, which in turn influences aquatic life.
Furthermore, biological activity and pollution can introduce or modify the isotopes present in water. This includes the by-products of living organisms as well as pollutants from human activity, altering the natural isotopic distribution. Other factors such as salinity, current, and tide, which are considered abiotic, can also play a role. Therefore, the most accurate answer is b. Geological processes and sources, complemented by temperature fluctuations and biological influences.