Formation and evolution of the Solar System depletion period that brought the asteroid belt down close to its present mass is thought to have followed when Jupiter and Saturn entered a temporary 2:1 orbital resonance (see below). The inner Solar System's period of giant impacts probably played a role in the Earth acquiring its current water content (~6 kg) from the early asteroid belt. Water is too volatile to have been present at Earth's formation and must have been subsequently delivered from outer, colder parts of the Solar System. The water was probably delivered by planetary embryos and small planetesimals thrown out of the asteroid belt by
Solid waste policy in the United States to more than 33%. The most recent numbers from the EPA indicate that in 2012 the US municipal solid waste recycle rate was 34.5%. This section describes the common methods of solid waste disposal practiced in United States and worldwide. Some of the main issues associated with waste are open dumping, odor, particulate matter emissions, leachate seepage from landfills, greenhouse gas (GHG) emissions that lead to air pollution, surface and groundwater pollution, food chain contamination, land area depletion, human health impacts, environmental degradation, and negative impacts on plant and animal life. All levels of government - federal, state, and local