The Research Of Characteristic In Water-Sediment And Remediation In Intensive Ponds Sediment

Sediment is a very important part of pond ecosystem. Many substance of the water is derived from water-sediment exchange. During cultivation, residual organic matter and oxygen-deprived in the bottom of the pond lead to sediment degradation and harmful bacterial reproduction and threat fish health. Sediment regulation is particularly important for the big breeding density and poor water quality, easy illness of aquaculture pond. The present research was carried on aerating to the sediment and planting lotus root to repair sediment of pond.The main research contents and main results are summarized as follows:1. The total phosphorus (TP) of sediment was composed mainly of inorganic phosphorus (IP), which accounted for87.4%. The concentration of Ca-bound phosphorus (Ca-P) and Fe/Al-bound phosphorus(Fe/Al-P) was accounted for60.4%,22.4%of TP, respectively. NH4+-N was the dominant form of sediment inorganic nitrogen. NH4+-N、NO3--N and PO43--P are tending to decline from the overlying water to the interstitial water, and thus there was the trend of release from the interstitial water to the overlying water. The TN in the sediment were positively correlated with NO3--N and NO2-N in the overlying water, which indicated that organic nitrogen compounds by decomposition pass through the water-sediment interface to overlying water, and was the important way to nutrient released from the sediment. Regression analyses showed that the activity of FDA were positively correlated with the contents of organic matter and the total bacteria in the sediment, which indicated that FDA can represent aquaculture ponds organic pollution and the total bacteria situation.2. The aerating to repair the sediment was studied. The concentration of NH4+-N was40-170mg·kg-1and NO3--N was5-18mg·kg-1. The results showed that the NH4+-N was the dominant form of sediment inorganic nitrogen. The accumulation of TP that aerating pond was0.02mg·kg-1, lower than jet aerator that concentration was0.38g·kg-1. The accumulation of aerating pond TN and LOI are higher than jet aerator, but there is no significant difference. Aerating to the sediment has a significant control function to total phosphorus deposition in sediment of pond.3. Planting lotus root to repair the sediment were studied. The results showed that the concentration of organic matter (0cm-5cm) and (5cm-10cm) were reduced11.45%and19.12%after planting lotus. Growing lotus root zone can promote the consumption of sediment organic matter, and remove total nitrogen and total phosphorous. AWCD of the experimental group and control group were higher than initial value, which indicated that microbial community metabolic activity of planting lotus sediment was higher. Different depth of sediment had different microbial community metabolic activity in the same environment. Metabolic and functional diversity of control group (0cm-5cm) sediment were significantly reduced (P＜0.05), and experimental group sediment were not sifnificant change (P>0.05). Planting lotus can keep higher the functional diversity of the sediment microbial communities.