Effects of highly volatile organochlorine solvents on soil nitrogen metabolism and microbial counts

The effects of highly volatile organochlorine solvents (1,1,1- trichloroethane, TCET; trichloroethylene, TCE; and tetrachloroethylene, PCE) on soil nitrogen cycle and microbial counts were investigated using volcanic ash soil with different fertilizations. All the solvents significantly inhibited the activity of the cycle under the sealed conditions with 10 to 50 mg/g (dry soil) solvents added. No significant difference between the solvents, and between fertilization plots, was observed. Nitrate ion was not accumulated, and instead, ammonium ion was highly accumulated in the presence of the solvents. Nitrite ion was partially detected, while l-glutaminase activity was inhibited. The growths of ammonification, nitritation, nitratation and denitrification bacteria, and filamentous fungi were significantly inhibited in the presence of 10 mg/g (dry soil) of the solvents.