Soil, anthropogenic black

Glaser, B., Balashov, E., Haumaier, L., Guggenberger, G., and Zech, W. (2000). Black carbon in density fractions of anthropogenic soils of the Brazilian Amazon region. Org. Geochem. 31, 669-678. 

Examples of anthropogenic phosphate minerals are shown in Figure 9.14 (Harris, 2002 University of Florida). Figure 9.14a shows patina of black, poorly crystalline apatite on the surface of an oyster shell located near the bottom of an early American mound, which once served as a refuse pile (about 5,000 YBP). Bones of fish and other animals were discarded in the pile and became the source of phosphorus that precipitated on the nnderlying shell. Note that oyster shells are composed of calcium carbonate, npon which phosphate readily adsorbs and precipitates (scale bar = 5 mm). Figure 9.14b shows vivianite as precipitate on an aggregate from stream sediment near Lake Okeechobee, Florida, collected a short distance downstream from where a dairy barn floor routinely flushed manure. Soils and stream sediments in the area are naturally low in phosphorus (scale bar = 1 mm). 

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