slots: sample type specific slots vs describing a property of the sample environment vs describing the sample

[mslarae13]

See

• Schema elements should have descriptions #813
• term total nitrogen concentration (tot_nitro) is water specific, should be general #680
• Duplicate term between Misc: and Soil package? #122

There's many terms that appear to be duplicate though some are specific to the sample vs environment. How should we handle these?

Options given for soils

Option1

• generalize when referring to environment vs the sample
• sample_ph ... environment_ph with some kind of qualifier

Option2

• sample_ph and slots for EACH environment pH
• soil_ph, water_ph

Other thoughts?