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. . I' I, .' . 3 ( Detection of accumulator species, if present in a seeding impact zone, could be inst.ruIrental with regard to protection and monitoring of animal and ht.lITBIl "food chains". \Vhereas, "sinks" for certain metals exist in some plant species, limited information concerning Ag translocation indicates rather uniform dis- tribution. It v.6uld appear that the layman and envirorunentalist have shown more concern than plant scientists for this issue. Recomne"'1dations In addition to identification of accumulator species, the relationship of uptake to total soil concentrations should be determined more accurately. If p:Jssible, a correlation between plant concentration and some empirical soil test could be established. From a hunan effects standPJint, this is not an issue of concern. Issue 6: Silver Interaction with Other tI.18tals Possible interactions of Ag with other heavy rretals have not been well studied and warrants investigation. Aside from Ag, n1.JI1leFOUS studies have been docu- mented which show that rretal interactions exist which may promote or depress uptake of either or roth of the involved rretals, by plants as an €.-'<:arnple. The complexity of the reactions is further complicated by such factors as soil pH, metal concentration, plant species, etc. This issue is of prime bnpor- tance to the scientist since the implications are subtle and not obvious to the lay public. In like rranner, the presence of silver from nucleating agent complexes nay interact in subtle ways with the movement and detoxification of the agents such as herbicides and pesticides. c RecoITl1l2ndations Basic physiological studies ranging from short-term solution culture to in situ soil studies might elucidate some of these relationships. Issue 7: Agents in Soil and Plants Seeding agents will be de}X)sited on land and will tend to be concentrat.ed in surface soil zones; exceptions include salts deposited in relatively rroist lcxalized environrrents. Plants and microbes may therefore by intirPately expJsed to relatively higher concentrations of seeding agents, The seeding agents can be expected to have little effect if they are not concentrated at higher than unit application levels by biological or physical processes, if they are not transfonned into rrore toxic or available forrns, and if they do not interact synergistically with other materials, (toxins, water stress, etc.). The possibility of concentration (chemical, biological) above background levels has been sh<::>vm, and will require further examination in the near future. The lack of public interest in this issue is likely due to the lack of knowledge ab::>ut, or empathy for plants and microbes and their p:Jssible i.rrpJrtance. Recomrendations studies of biological and physical concentration mechanisms, s~gistic effects, and bio-physical transfonnations of silver should be considered. c: ----- -