ZHANG Yun, ZHANG Sheng, LIU Chang-li , SONG Chao, WANG Xiu-yan, Joseph PANG, WANG Jun-kun

(Institute of Hydrogeology and Environmental Geology, Chinese Academy of Geological Sciences , Zhengding 050803, China)

Abstract: The impact factor of denitrification of vadose zone soil is complex. Currently there is no good method to be applied directly to measuring the denitrification strength. After comparing a variety of relevant methods, this paper chose “to increase the permeability of soil substrate disappearance balance method " as a guide and tried to use the way of applying a certain nitrate liquid manure to the situ permeability soil box of the field，with the simultaneous test of soil organic nitrogen mineralization, microbial retention of inorganic nitrogen，and ammonia volatilization, crop uptake of nitrogen value , etc. and then with the soil net nitrate input, background value, final value and changes in value of ammonia nitrogen involved in calculating equilibrium, solving the value of soil denitrification (“improvement balance method ”for short), so as to make a study on the determination of strength of denitrification for different soil quality, thickness, soil organic matter consumption, permeability soil box or soil column under soil water potential. The results showed that different thickness, soil organic matter consumption, permeability soil box and sandy soil or mild clay column under soil water potential as mentioned above produced a range of 8.07~16.54mg.m-3 and 6.23 ~ 26.4 mg.m-3 of NO3-N removal, compared with the original method of determination of a range of 7.29~11.42mg.m-3 and 5.38 ~ 18.1 mg.m-3's removal to a certain extent increased. This is mainly due to the improved method reflecting complementally the effect of soil organic nitrogen mineralization. It eliminated some deficiencies in the original method, and not only revealed the soil denitrification phenomenon, but also described a more comprehensive picture of environmental factors on soil denitrification consequences. The method is more suitable for protection against the vadose zone soil contamination of groundwater denitrification measured, so as to provide services for agricultural pollution control and protection of groundwater caused by nitrogen leaching.

Key words: groundwater pollution protection; vadose zone soil; denitrification

EARTH AND ENVIRONMENT Vol. 39, No.2, Tot No.283, 2011, Page 263-272