冬季水生植物分解过程及其对水质的影响研究

通过室内模拟实验,研究太湖3种常见水生植物芦苇(Phragmites australis)、马来眼子菜(Potamogeton malaianus)和荇菜(Limnanthemun nymphoides)冬季分解过程以及对水质的影响。结果表明:芦苇、马来眼子菜和荇菜的快速分解期为前4 d,在这4 d内干物质分别减少了15.9%、12.9%和38.8%;第4~48 d为缓慢分解期,3种水生植物干物质剩余量差异显著(P<0.01)。分解速率k与植物残体内的C/N显著负相关(P<0.01,n=54),与C/P呈显著负相关(P<0.01,n=54)。实验前4 d,植物组水体p H、DO值迅速下降,之后缓慢上升,总体都表现为对照组>芦苇组>马来眼子菜组>荇菜组;实验初期,植物分解向水体中释放大量N、P营养物质,水体TN、TP分别在第2、4 d达到最大,但是其对水质影响具有时效性,实验后期各组水质均无明显差异。

Decomposition of Aquatic Plants During Winter and Its Influence on Water Quality

In winter large proportion of aquatic plants die, decompose and then release nitrogen and phosphorous nutrients into water, which consequently impacts water quality. An indoor simulation experiment was carried out to study the decomposition process of three aquatic plants including Phragmites australis, Potamogeton malaianus and Limnanthemun nymphoides, typical in Lake Taihu, in winter and the subsequent influence on water quality. Phragmites australis, P. malaianus and L. nymphoides had a fast decomposition rate during the first 4 days but decomposed much slowly from day 5 to day 48 in terms of biomass loss. The dry matter of these three plants respectively decreased by 15.9%, 12.9% and 38.8% in 4 days. Significant differences were observed in the remained dry matter of three plants(P<0.01). The decomposition rate k was significantly negatively correlated with plant C/N and C/P(P<0.01, n=54). The pH and dissolved oxygen(DO) of the water body decreased rapidly during the first 4 days and increased slowly thereafter, and they were generally control > P. australis > P. malaianus > L. nymphoides. Total N levels reached the maximum value at the second day and TP attained the highest value at the fourth day. The influence of decomposition of aquatic plants on water quality was transient as no significant difference was observed in water quality parameters at the end of the experiment.