Lithosphere and Hydrosphere – EST supplement 1. Buffering Capacity p. 193– soil’s ability to resist changes in its PH when acidic or alkaline compounds are added to it. (plants adapt between PH of 6-7; conifers prefer more acidic soil.) 2. Permafrost p. 194– is ground whose temperature has been 0° C or lower for at least 2 years. (50% of Canada covered in permafrost; in certain regions, the top layer called active layer thaws for growing then the ground later freezes again). 3. Pollution and Degradation p. 199 – soil depletion = loss of soil fertility, due to for example use of heavy machinery, as well as compaction which prevents rain from penetrating earth. Farmers compensate by adding fertilizer that pollutes lakes, threatening biodiversity. Contamination is the abnormal presence of a harmful substance in an environment. Examples: gas station leaks, metals, sulphur dioxide and nitrogen oxide emissions causing acid rain, which drastically affects ecosystems. 4. Pollution and Degradation p. 211 – threats to hydrosphere: chemicals, warm waters from factories (thermal pollution – which lowers oxygen solubility) 5. Eutrophication p. 212 – pollution comes from identifiable sources called point sources or non-point sources which are spread out over a broad area. Living organisms can degrade some but not all contaminants. Effects of aquatic pollutants depend on their toxicity and concentration, especially affecting stagnant lakes or marshes. Eutrophication =