The "natural" process is that e.g. oysters grab the co2 and bad stuff from the water, die, sink to the bottom and get covered in sediment. That's where major carbon sinks ended up anyway, to be turned into oil/coal/gas over millions of years.
Smoke detector radiological sources, teflon pans, noble gases and refridgerants, cadmium paints and pigments, dioxins, kepone, BPA, hydrazine, sulfur mustards, medication, depleted uranium. The list goes on.