[Influence of two different species of aquatic plant communities on the concentration of various nitrogen forms in sediment of Lake Taihu].

Le résumé fourni par la source

To investigate the spatial distribution of nitrogen in the sediment from both internal and external sites of Potamogeton malaianus and Limnanthemun nymphoides communities, levels of various forms of nitrogen were quantified in sediment samples collected from Gonghu Bay, the southern region and the intermediate area between East and West mountains of Lake Taihu in June 2012. The results showed that: (1) Within the algae-type region in Gonghu Bay, the contents of organic (Org-N) and total nitrogen (TN) in the internal sediment (0-25 cm) from P. malaianus communities were higher than those of the external sediment, by 38.06% and 25.65%, respectively. (2) In the non-algal region, the contents of TN, Org-N, NH4(+)-N and NO3(-) -N in the internal sediments from P. malaianus communities were lower by 43.29%, 50.78%, 7.09% and 10.86% compared to those in the external sediments; for L. nymphoides communities, the contents of TN, Org-N, NH4(+) -N and NO3(-) -N in the external sediments were lower by 4.65%, 4.63%, 5.01% and 2.76% compared to the internal sediments. These values suggested that the promotion in reducing sedimentary nitrogen was more effective by the P. malaianus community than by the L. nymphoides community. (3) A significant positive correlation (P < 0.05, n = 24) was found between pH and TN within the external sediments and between pH and NO3(-) -N within the internal sediments (P < 0.05, n = 24), while a significant negative correlation (P < 0.05, n = 24) was found between pH and NH4(+)-N of both aquatic plant communities. The redox potential (Eh) was also found to be significantly positively correlated with TN in both the internal and external sediments of P. malaianus communities (GMN, P < 0.01, R = 0.922 8 * *; NMN, P < 0.01, R = 0.827 7 * *; GMW, P < 0.05, R = 0.748 9 *; NMW, P < 0.05, R = 0.663 7 *). It is therefore concluded that the presence of aquatic plant communities could impact the physical and chemical properties of the sediments.

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