Not only was the spatial distri bution well defined, but the lead and 

 arsenic concentrations decreased sharply with depth. Highest amounts were 

 evident in the organic-rich surface horizons, while in the subsoil the 

 values rapidly decreased to background levels. A subsequent study in ten 

 old, heavily contaminated orchards revealed more or less the same patterns. 

 The lead always was associated with the organic material in the surface 

 layer, some orchards having values up to 4400 ug/g (4000 lbs/acre). Arsenic 

 concentrations usually were ? to 4 times less than the lead concentration at 

 the same point, resulting in values up to 1300 ug/g (1?00 lbs/acre''. The 

 maximum peak of arsenic often was below the depth of highest accumulation of 

 lead, indicating that the arsenic may have moved within the soil profile, 

 although prohably not to any great extent. Since arsenic in its behavior is 

 related to phosphorus, i.e. it can be removed by phosphorus applications 

 from the exchange sites on the clay particles, it appears wise to limit 

 applications of phosphorus-containing fertilizers in contaminated orchards 

 to just what is needed for plant-uptake. 



In the survey of the ten old orchards in various parts of Massachusetts 

 a few sites did not show any high values for either lead or arsenic. One 

 possible explanation may be that in some orchards it was customary to let 

 cows or other animals graze. Since the lead-arsenate material is virtually 

 insoluble, a significant portion of the residues adhered to the grass 

 plants and may have been removed by the grazing animals. The presence of 

 old orchards, therefore, does not necessarily mean that one automatically 

 has a contaminated site. The survey also indicated that soils with high 

 clay contents tended to retain arsenic better than sandier soils. 



A common inquiry is, "How do I remove the lead-arsenate or at least 

 bring it to within acceptable limits?" Stripping the entire site of surface 

 soil is impractical, costly and often unnecessary. The best solution to 

 this type of pollution is dilution in the form of plowing, making sure that 

 the plow turns the soil over as much as possible. Vegetable gardening 

 should be discouraged or limited to non-leafy produce, depending on the 

 level of contamination. 



POMOLOGICAL PARAGRAPH 



Wil 1 iam J. Lord 



Lime for Scrubbing CA Storages . Occasionally growers receive lime that is 

 not fresh and it fails to absorb adequately the carbon dioxide in the CA 

 room. It may be completely ineffective or become ineffective after only 2 

 or 3 months. 



D'*y lime for CA rooms should be fresh, high in calcium and have a 

 magnesium content not over 10?^. Specification for good lime for CA rooms 

 would be "fresh hydrate with about ''^-1^1- calcum oxide and only 1-?% magne- 

 sium oxide." 



If a "^0 pound bag of hydrated lime weighs more than 'i5 pounds you can 

 be pretty sure that it is worthless for scrubbing. Another simple test to 

 determine suitability for use in CA rooms is to place 3 tablespoons of the 

 lime into a glass and add 3 tablespoons of water while stirring with a ther- 

 mometer. If the temperature of the water does not increase it means that 



the material is probably useless. If it goes up ^-3 degrees, it is 

 suitable. 



