Table 1.

Generalized properties of sediments and soils (Carr et al. 2003, Bergtold and Traunspurger 2004, Shurin et al. 2006, Zhu et al. 2006, Glud 2008, Grosberg et al. 2012, Hernandez et al. 2014, Knapp et al. 2017).

	Marine sediment	Freshwater sediment	Soil
Composition of top layer	20%–60% solid, 40%–80% liquid	20%–60% solid, 40%–80% liquid	Approximately 50% solid, 25% liquid, 25% gas
Temperature	Limited seasonal fluctuations and latitudinal gradients in subtidal environments (4°C–6°C, 700–1200 m throughout most oceans); intertidal areas can reach temperatures of more than 30°C in summer and below 0°C in winter	Limited seasonal fluctuations and moderate latitudinal gradients (5°C and 8°C at 16 m water depth in temperate lake in Germany, almost constant 14°C at 50 m water depth in tropical lake (Mexico)	Often large diurnal and seasonal fluctuations and latitudinal gradients (from –30°C in the arctic to 40°C in the tropics)
Salinity	Electric conductivity approximately 50 dS per m; typically, 30–40 g NaCl per l; site specific; fairly constant over time	Electric conductivity below 0.56 dS per m in temperate lake (Germany), 13 dS per m in tropical lake (Mexico); site specific; fairly constant over time	Electric conductivity approximately 1–15 dS per m; typically, up to 0.5 g NaCl per l; site specific; variable over time
Typical pH	Narrow range; pH 6.5–8.5; gradients of up to 2 pH units on a subcentimeter scale	Narrow range; pH 6.5–8.5 (temperate and tropical lakes)	Wide range; pH 3.5–9.0
Redox zone	Oxic and suboxic in the approximately 10-cm top layer; vertical oxygen distribution strongly affected by the activity of fauna	Temperate lakes: small oxic and suboxic top layer; tropical lakes: often anoxic hypolimnia, top layer anoxic	Oxic and suboxic in 20–40 cm top layer (depends on soil texture); beneath 40 cm anoxic
Medium	Transport of materials and organisms by convective forces of waves and currents extends the spatial scale of many processes (generally less in freshwater than marine sediments)		Magnitude of the zone of capillary rise dependent on soil texture (shallower in sandy than in clay or peat soils); downward transport of materials and organisms mainly as a result of precipitation

Note: Given the wide variety of sediment and soil habitats, properties listed should not be taken as fixed characteristics for either of the three major habitat types. Abbreviations: °C, degrees Celsius; cm, centimeters; dS, decisiemens; g, grams; l, liters; m, meters, NaCl, sodium chloride.