A I en IK Y OI'KRAIIONS 



107 



AUMIMSIRAI 1U.\ lOR LSI. Willi lool) MSll. ll.BKl AK'l, I!i7i. SOIRC'K MKVF.R i: I 



AI'PLICAIION 



RATES 



MODL t)K 

 ACTION 



COM MEN is" 



0.1 -.").(> ppm 



2-3 pounds/acre 



()..')-2.() ppm 

 1-3 ppm 



0.3-2.0 ppm 



(10-40 pounds/ 



(acre) 

 3-l,T pounds/acre 



Nonsystemic 



Nonsystemic 



Probably 



nonsystemic 

 Systemic 



Systemic 



Limit is one part per million for 

 copper complexes, but 



CuS04-5H20 and basic copper 

 carbonate are exempted from 

 the limit 



Interim limit in potable water is 

 0.01 part per million 



Interim limit in potable water is 

 0.2 part per million 



Upper limits are 12 parts per mil- 

 lion in raw fish and 0.01 part 

 per million in potable water. 



Upper limit in raw- fish and shellf- 

 ish is 1 part per million. 



oxygen capacity: less oxygen dissolves in water at higher temperatures. It 

 has an indirect effect on oxygen circulation: as temperature rises, water be- 

 comes more difficult to mix. If temperatures rise high enough, and the wa- 

 ter is deep enough, the pond may stratify into an upper, warmer, wind- 

 mixed layer and a lower, cooler, poorly circulated layer. In such cases, lit- 

 tle water moves across the thermocline separating the two layers. The 

 upper layer receives, and keeps, most of the new oxygen (chiefly from pho- 

 tosynthesis by phytoplankton); the lower layer receives little new oxygen, 

 and loses it — sometimes completely — to respiration (chiefly by bacteria). 

 Several pond management techniques attempt to overcome the effects such 

 temperature- induced stratification has on the oxygen supply. 



It is easy to see why pond-oxygen problems are more acute in summer 

 than in autumn, winter, and spring. When the water is cool, it can dissolve 

 more oxygen, and it is more easily mixed by wind action to the pond bot- 

 tom. Photosynthesis is less, but so is respiration, and photosynthetic oxy- 

 gen is kept in the pond. 



In contrast, vr-ater circulation is constrained in summer. In the upper 

 layers, especially in stratified ponds, photosynthesis may be so intense that 

 the water becomes supersaturated with oxygen so that much of the gas is 



