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| Influence of physical amelioration on the characteristic of sediments and pore waters in Lake Nansi Wetland |
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Abstract Investigation was carried out to evaluate the impact of physical amelioration treatments (fine sand covered and sediment loosened) on the sediments and pore water in Lake Nansi wetland in China. Oxygen micropro?les near sediment-water interface and the vertical distribution of pore-water nutrients (PO43-, NH4+, NO3- and NO2-) in the uppermost sediment were determined. The treatments could effectively improve sediment physical structure (i.e. water content, porosity et al.) and oxygen depth-distribution. The oxic zone thickness at sediment-overlying water interface was significantly widened in fine sand covered and loosened sediments treatments compared with those in-situ sediments treatment(P <0.05), and the oxygen furthermost penetrations were determined in fine-sand covered treatment. The NH4+ and PO43- distribution in the vertical profile exhibited a nearly exponential increase and a NO3- decrease with depth in 10 cm surface sediment, indicating an approximate constant concentration below 10 cm depth. Otherwise, dissolved oxygen sharply deceased with depth at the water-sediment surface and arrived near zero mg/L at the 4 mm depth. All treatments could decrease PO43- concentration in pore water, and the lowest interstitial PO43- concentration was found in slightly loosened sediment treatments (P <0.05). Also, NH4Cl-extractable PO43- and bicarbonate dithionite (BD)-extractable PO43- contents increased significantly in slightly loosened sediment treatment, especially in surface.
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Received: 21 July 2009
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