河流线型对河流自净能力的影响

Influences of the River Linear Forms on River Self-purification Capacity

为研究河流线型对河流自净能力的影响,选取5条具有不同河流线型的河涌进行研究,以弯曲度和分形维数表征河流线型,以TP、NH 3-N、NO 2-N、NO 3-N、COD Cr、TOC、DOC、叶绿素(Chlorophyll)和蓝绿藻藻蓝蛋白(BGA-PC)等9项水质指标沿程削减率表征河流自净能力,并分析各研究河段的悬浮微生物生物量和生物活性,探讨河流线型影响河流自净能力的作用机制。结果表明:多项水质指标沿程削减率随河流线型蜿蜒程度的增加而提升。在直立式浆砌石挡墙河段,河流线型通过提高悬浮微生物生物活性,进而增强河流自净能力,使TP、NH 3-N、NO 3-N、DOC、Chlorophyll和BGA-PC的沿程削减率显著提升;而在格宾石笼挡墙河段,河流线型通过增加悬浮生物生物量和提高生物活性,进而增强河流自净能力,使NO 2-N、COD Cr、TOC和DOC的沿程削减率显著提高。

5 stream segments with different river linear forms were investigated to reveal the influence of the river linear forms on river self-purification capacity. River linear forms were characterized by sinuosity and fractal dimension. Furthermore, along-path reduction rates of 9 water quality indicators including TP, NH3-N, NO2-N, NO3-N, CODer, TOC, DOC, Chlorophyll and Blue-green algae phycocyanin （BGA-PC） were used for characterization of the river self-purification capacity. Suspended microbe biomass and bioactivity was analyzed and mechanism of the influence of river linear forms on the river self-purification capacity was discussed. The results indicated that most of the along-path reduction rates of water quality indicators rose with the meander increase of river linear forms. In the stream segment with the river bank of vertical masonry retaining wall, such river linear form affected the river self-purification capacity by enhancing suspended microbe bioactivity, significantly increasing the along-path reduction rates of TP, NH3-N, NO3-N, DOC, Chlorophyll and BGA-PC. In the stream segment with the river bank of gabion retaining wall, the river linear form affected the river self-purification capacity by increasing suspended microbe biomass and bioactivity, significantly improving the along-path reduction rates of NO2-N, CODe,, TOC and DOC.