The habitat is the specific environment for a species defined by its requirements.
Humic substances are natural organic macromolecules formed during the degradation/decomposition of plant remains in the soil (humus). Sources for the production of humic substances are turf and young lignite (brown coal).
Hydrogeology (Gr. ύδωρ [hydor] - water, γέα [gea] - the Earth, λόγος [logos] - word) is the science of water associated with the Earth's crust. Hydrogeology is a discipline of the geosciences.
The science that deals with water as it occurs in the atmosphere, on the surface of the ground, and underground (definition by USGS; http://capp.water.usgs.gov/GIP/h2o_gloss)