Study On The River Meandering Degree Impact On The River Self-purification Capacity

7stream segments which have different river meandering degree were investigated toreveal the relationship between river meandering degree and river self-purification capacity,and understand the different influence of the river meandering degree on the self-purificationcapacity of the river under different revetment form. The river meandering degree wascharacterized by sinuosity (S) and fractal dimensions (DB). In addition, characterization ofriver self-purification capacity was using the suspended microbial biomass、suspendedmicrobial enzyme activities、evolution with distance of inorganic nitrogen content andalong-path reduction rate of water quality indexes, including TP、NH3-N、NO2-N、NO3-N、CODcr、TOC、DOC、Chlorophyll and Blue-green algae phycocyanin (BGA-PC). Samplinganalysis during the dry season and rainy season, quantitative research the influence of theriver meandering degree on the self-purification capacity of the river under the streamsegment which have the vertical masonry retaining wall river bank or the gabion retainingwall river bank. Suspended microbial biomass and enzyme activities were investigated toreveal the mechanism of river meandering degree on river self-purification.The results show that river meandering degree has significant influence on theself-purification capacity of the river which have the vertical masonry retaining wall riverbank. Most of along-path reduction rate of water quality indexes are enhanced with the theincrease meander of river linear form, especially the DOC、BGA-PC and inorganic nitrogenreduction ratio. Those parameters are observed increase in the eastern section of the ModieshaRiver, and decrease in the western section during dry season. In rainy season, DOC reductionratio still increase in the eastern section of the Modiesha River, and decrease in the westernsection. The BGA-PC and inorganic nitrogen reduction ratio are1.60times (P<0.05) and2.39times (P<0.05) of western section to eastern section. The DOC reduction ratio of Yunxi Riverduring the dry season for the western is only1/2.53(P<0.05) of the eastern, while BGA-PCand inorganic nitrogen concentrations increase in the eastern section of the Yunxi River, anddecrease in the western section.DOC、BGA-PC and inorganic nitrogen reduction ratio are alsoobserved increase in the eastern section of the Yunxi River, and decrease in the westernsection during rainy season. The river which has higher degree of meander has higher waterself-purification ability, in the stream segments of Modiesha river and Yunxi river.River meandering degree also makes significant influence on the self-purificationcapacity of the river which have the gabion retaining wall river bank. During dry season, most of along-path reduction rate of water quality indexes are enhanced with the the increasemeander of river linear form, especially the DOC reduction ratio. DOC reduction ratio isobserved increase in the straight section of the Yufeng River, and decrease in the northern andsouthern section of the Nanpai River during rainy season, and that, the DOC reduction ratio is2.47times (P<0.05) of northern to southern section. In the rainy season, NH3-N、NO2-N、CODcr、TOC、DOC and BGA-PC reduction ratio are enhanced with the the increase meanderof river linear form. Within the scope of the river meandering degree, the river segment whichhas higher degree of mender has higher water self-purification ability.The influence of the river meandering degree on the suspended microbial lipidphosphorus content in the stream segment which have the vertical masonry retaining wallriver bank is non-significant, but the suspended microbial FDA hydrolase are enhancedsignificantly with the increase meander of river linear form. In the stream segment which havethe gabion retaining wall river bank, suspended microbial lipid phosphorus and FDAhydrolase activity are enhanced significantly with the the increase meander of river linearform, In the stream segment which have the vertical masonry retaining wall river bank, rivermeandering degree affect river self-purification capacity by enhancing suspended microbebioactivity. On the other hand, in the stream segment which have the gabion retaining wallriver bank, river meandering degree affect river self-purification capacity by increasingsuspended microbe biomass and bioactivity.The along-path reduction rate of water quality indexes、suspended microbial lipidphosphorus content and suspended microbial FDA hydrolase of the river which have thegabion retaining wall river bank during rainy season have significant positive correlation onsinuosity and fractal dimensions. The result further illustrate that river meandering degree hassignificant correlation with the self-purification capacity of the river which have the gabionretaining wall river bank。...