IMPACT OF ARSENICALS ON NITRIFICATION 



297 



DAYS 



Fig. 3 Impact of arsenate on Nitrobacter. •, no arsenic; O, 0.1 mg 

 As/liter; D, 1 mg As/liter; ■,10 mg As/liter; A, 100 mg As/liter; and 

 A, 1000 mg As /liter. 



desirable. The agricultural industry prolongs the availability of 

 nitrogen fertilizer by applying N-SERVE [2-chloro, 6-(trichloro- 

 methyl) pyridine], an inhibitor specific for Nitrosoinonas (Campbell 

 and Aleem, 1965). When the oxidation of ammonia to nitrite is 

 inhibited, the nitrogen remains in a relatively immobile form, 

 ammonia, but it is still available for plants. Pesticides such as 

 lindane, Malathion, and Baygon also inhibit nitrification at this first 

 stage (Garretson and San Clemente, 1968). It may also be desirable 

 to control nitrification in streams and lakes because it contributes a 

 significcint oxygen demand in some waters. Theoretically, 4.57 mg of 



