Final answer:
Long term storage of minerals released slowly over time by weathering is known as reservoir in the context of biogeochemical cycles. It represents the long-term storage of minerals in rocks, soil, and deep groundwater.
Step-by-step explanation:
Long term storage of minerals that are released slowly over time by weathering is known as reservoir in the context of biogeochemical cycles. A reservoir is a part of a biogeochemical cycle that holds an element or water for a long period of time. In the case of minerals, such as phosphorus, which can be cycled from land to water through rain and surface runoff, the reservoir represents the long-term storage of these minerals in rocks, soil, and deep groundwater.