菹草(Potamogeton crispus)附着物对水体氮、磷负荷的响应

The impact of periphyton attached on Potamogeton crispus on nitrogen and phosphorus loads in water

通过实验模拟了10组氮、磷负荷对菹草(Potamogeton crispus)生长期和衰亡期茎叶附着物的影响.结果显示:随着水体氮、磷浓度的升高,菹草附着物的叶绿素a(Chl.a)含量、附着有机物量、附着无机物量和附着物总量均增加,在氮、磷浓度最高的T10组(总氮12.0 mg/L,总磷1.0 mg/L),附着物的总量达到高峰,附着物的Chl.a含量为2.005～4.765mg/g(DW),附着有机物的量为29.027～94.886 mg/g(DW),附着无机物的量为176.881～397.750 mg/g(DW),附着物总量为205.909～492.636 mg/g(DW).在菹草的快速生长期、稳定期和衰亡期,附着物的Chl.a含量、附着有机物量、附着无机物量和附着物总量均存在显著差异,均表现为衰亡期>稳定期>快速生长期,且在各营养盐浓度下均存在这一趋势.菹草衰亡期附着物的Chl.a含量、附着有机物量、附着无机物量和附着物总量分别为稳定期的1.046～1.826、1.046～1.638、1.029～1.858和1.106～1.717倍,为快速生长期的2.324～4.059、2.323～3.640、2.101～3.792和2.280～3.584倍.结果表明水体氮、磷负荷的增加促进了菹草茎叶附着物的生长和积累,加速了沉水植物衰亡.

To explore the role of periphyton in nutrient cycle in eutrophic shallow lake, the effect of the periphyton attached on Potamogeton crispus on nitrogen and phosphorus loads was examined in a mesoeosm experiment conducted in controlled greenhouse. A gradient of ten nutrient concentrations （ nitrogen concentrations from 3 to 12 mg/L and phosphorus concentrations from 0. 1 to 1.0 mg/L） was established with NH4 Cl, NANO03, KH2 PO4. The results showed that： The content of periphyton chlorophyll-a （ Chl. a）, organic matter, inorganic matter and total periphyton increased significantly with nitrogen and phosphorus loads increase. The content of periphyton Chl. a, organic matter, inorganic matter and total periphyton reached peak at T10 （TN 12 mg/L, TP 1.0 mg/L） with Chl. a 2. 005 -4. 765 mg/g（DW） periphyton, organic matter 29. 027 -94. 886 rag/g（DW） Potamogeton crispus, inorganic matter 176. 881 -397. 750 mg/g（DW） Potamogeton crispus, and total periphyton 205. 909 -492. 636 rag/g（DW） Potamogeton crispus, respectively. Periphyton Chl. a, organic matter, inorganic matter and total periphyton generally inereased with time. Differences in periphyton Chl. a, organic matter, inorganic matter and total periphyton were significant among growth periods, and showed rapid growth period 〉 stable period 〉 decline period. Moreover, this trend oecurred at all nutrient concentrations. The periphyton Chl. a, organic matter, inorganic matter and total periphyton of decline period were 1. 046 - 1. 826,1. 046 - 1. 638,1. 029 - 1. 858 and 1. 106 - 1. 717 times those of stable period, and were 2. 324 - 4. 059,2. 323 - 3. 640,2. 101 - 3. 792and 2. 280 - 3. 584 times those of rapid growth period. The results above indicated that the periphyton of Potamogeton crispus and its decline were enhanced by elevated nitrogen and phosphorus loads.