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<br />Ecological Effects <br />TABLE 3. Published Silver Burdens in Terrestrial Organisms <br /> <br />93 <br /> <br />Organism <br /> <br />Ag Content (ppm dry <br />matter unless noted) <br /> <br />Reference <br /> <br />Other Information <br /> <br />.... PLANT <br />I <br /> <br />1: <br /> <br />Yeast <br />Fungi <br /> <br />detected <br /> <br />detected in ash <br />0.15 <br />up to several hundred <br /> <br />Bryophytes <br /> <br />9.0 <br /> <br />Ferns <br /> <br />O.l <br /> <br />0.23 <br /> <br />0-2.0 in ash <br />0.23 (1.0 in ash) <br /> <br />Horsetails <br /> <br />Vascular plants <br /> <br />5.0 <br /> <br />Gymnosperms <br /> <br />0.07 <br />0-1.4 (0-30.0 in ash) <br /> <br />0-.28 (0-3.0 in ash) <br />0.9 <br /> <br />Angiosperms <br /> <br />ANIMAL <br /> <br />Molluscs <br /> <br />0.16-0.8 <br /> <br />Mammals <br /> <br />0.05-0.7 <br /> <br />0.006 <br />0.01 <br />0.005-0.04 <br />concentrations near the <br />limits of detection <br /> <br />Saccharomyces cerevesiae Porter [1946] <br /> <br />Aspergillus niger <br />includes lichens <br />mushrooms <br /> <br />Siu [1951] <br />Bowen [1966] <br />Browning [1961] <br /> <br />Shacklette [1965] <br /> <br />Bowen [1966] <br /> <br />Bowen [1966] <br /> <br />Cannon et al. [1968] <br />Warren and DelavauU <br />[1950] <br /> <br />Shacklette [1965] <br /> <br />in7.9%ofall <br />bryophyte samples <br /> <br />Equisetum sp. <br />Equisetum sp. <br /> <br />in 1.5 % of vascular <br />plants sampled <br /> <br />in grains and cereals <br /> <br />Bowen [1966] <br />Warren and Delavault <br />[1950] <br />Warren and Delavault [1950] <br />Browning [1961] <br /> <br />shell of Unio mancus <br />(land snail) <br /> <br />flesh of Unio mancu.~ Bowen [1966] <br /> <br />Bowen [1966] <br />bones (apatite) Bowen [1966] <br />various soft tissues Bowen [1966] <br />in each of 29 human Tipton and Cook [1963] <br />organs or tissues assayed <br /> <br />Bowen [1966] <br /> <br />~. <br /> <br />there are no plant indicators of silver useful <br />in geobotanical prospecting. Reported silver <br />burdens in plants vary widely (Table 3). <br />Data on silver concentrations in the bodies of <br />terrestrial animals (Table 3) are even scarcer <br />and less reliable than data for plants. There is, <br />however, no evidence that any terrestrial ani- <br />mals are confirmed concentrators of silver. <br />There seems little likelihood that this element <br />will build up through terrestrial food chains to <br />a level that is dangerous to other organisms. <br />Biological concentration in aquatic ecosystems. <br />Many marine organisms definitely concentrate <br />silver and other heavy metals relative to their <br />environment (Table 4). Others, particularly <br />corals, discriminate against silver relative to <br /> <br />I <br />t <br /> <br />such elements as calcium [Veeh and Turekian, <br />1968]. There has never been any indication that <br />marine organisms which concentrate silver suffer <br />in any way as a result. However, silver levels <br />to which marine organisms are well adapted <br />could be harmful to organisms that have evolved <br />in fresh water lacking such ions. <br />Virtually all of the available data for silver <br />concentrating mechanisms in aquatic systems <br />are for marine situations, largely because most <br />such measurements have been made in con- <br />nection with studies of marine geochemistry. <br />Brooks and Rumsby [1965] suggest the follow- <br />ing pathways for concentration of trace ele- <br />ments by marine molluscs: (a) particulate in- <br />gestion of suspended matter; (b) ingestion of <br />