Research on the distributive characteristics in NH 4 N concentration of interstitial water in shrimp pond is presented in this paper. The results show that the NH 4 N concentration in the interstitial water remains an increasing tendency in the process of Penaeus japonicus culture. This mainly relies on the amount of sediment which consists of the organic matter such as the residul and the excrements of shrimp, the fyagments of organisms and the suspending particles of having absorpted NH 4 N in the bottom of pond. As water resource must pass mudlate, the distribution of NH 4 N concentration in the interstitial water is adit of water>centre ditc>outfall of water. The veritical distributions of its concentration is 10 cm layer>5 cm layer>0 cm layer, and the NH 4 N concentrations of each layers tend to be close to that in the middle and later stage of shrimp culture. The NH 4 N concentration show a positive correlation with the contents of COD, and a negative correlation with Eh. The effect of the NH 4 N of the interstitial water on P.paponicus culture and some measures for improving the substrate environment of pond are also discussed here.
