| With the strong development of sea cucumber pond breeding, the aquaculture water pollution becomes a serious problem. Sediments play vital role on pond environment pollution. To understand the rhythms of nitrogen（N） and phosphorus（P） in the sandy and the silty sediments ponds for sea cucumber breeding, the sandy and silty sediments samples in the upper（0～2 cm） and lower（3～5cm） layers near the inlet, middle area and the outlet of sea cucumber breeding pond were collected from March to November in 2011, respectively. The spatial and temporal distribution characteristics of total nitrogen（TN） and total phosphorus（TP） in sandy and silty sediments were investigated. The results showed that TN contents ranged from（0.16±0.05）mg·g-1 to（0.29±0.03）mg·g-1 in sandy sediments, that in silty sediments ranged from（0.13±0.06）mg·g-1 to（0.67±0.09）mg·g-1. TN contents in silty sediment were in an upward trend in overall. The one-way ANOVA showed that there was no significant difference in the TN contents between the sandy and the silty sediments from March to June（P>0.05）, but a significant difference occurred from July to November（P<0.01）. TP contents ranged from（0.02±0.02）mg·g-1 to（0.09±0.07）mg·g-1 in sandy sediment, that in silty sediment ranged from（0.50±0.02）mg·g-1 to（0.72±0.04 ）mg·g-1. In the two sediments, the TP contents decreased first and then increased during the investigating period, reached the lowest in August. TN and TP contents in upper sediment were slightly higher than that in lower sediment, while the difference between the two layers was not significant（P>0.05）. The TN and TP contents were both the lowest in the two sediments near the inlet area. There was no big difference on TN contents in sediments near the middle and the outlet areas. TP contents in the middle area were both higher than that in the outlet area during the early and late investigating period. Moreover, the difference turned out to be bigger in the late investigating period. Comprehensively, the sandy sediment might be more beneficial for healthy and sustainable development of the sea cucumber breeding. The silty sediment could have internal pollution risks because of higher N and P accumulation contents. |
