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891.
A New Approach for the Flocculation Mechanism of Chitosan 总被引:2,自引:0,他引:2
A peak III/I ratio (peak) in pyrene-fluorescence spectrum was used to measure the polarity of microenvironment of chitosan adsorbing pyrene molecules. The authors detected the pyrene-fluorescence spectrum of chitosan with different degrees of deacetylation (DD) and determined the relationship between the flocculation of bentonite colloid and the peak of chitosan with a different molecular weight (MW) and DD. It can be concluded that MW rather than DD plays a key role in the flocculation and that bond bridging rather than charge neutralization dominates the flocculation with chitosan from a microenvironmental structure of view. 相似文献
892.
893.
894.
Carl E. Korschgen Gerry A. Jackson Laura F. Muessig Deborah C. Southworth 《Journal of the American Water Resources Association》1987,23(2):221-226
ABSTRACT: Sediment accumulation was evaluated in Lake Onalaska, a 2800-ha backwater impoundment on the Upper Mississippi River. Computer programs were used to process fathometric charts and generate an extensive data set on water depth for the lake. Comparison of 1983 survey data with pre-impoundment (before 1937) data showed that Lake Onalaska had lost less than 10 percent of its original mean depth in the 46 years since impoundment. Previous estimates of sedimentation rates based on Cesium-137 sediment core analysis appear to have been too high. 相似文献
895.
Roy C. Sidle Alan J. Campbell 《Journal of the American Water Resources Association》1985,21(6):909-917
Suspended sediment data from a 154 ha watershed on northeast Chichagof Island, Alaska, were collected over three fall storm seasons from 1980 to 1982. Sediment rating curves for nine pooled storms explained less than 34 percent of the variation in total suspended solids (TSS). Significantly higher concentrations of suspended sediment occurred during the rising limb of storm hydrographs than for similar flows on the falling limb, accounting for hysteresis loops in TSS versus streamflow plots for individual storms. These hysteresis loops were wider during early season storms, indicating that easily transportable fine sediment may have been flushed from the upper portion of channel banks and from behind large organic debris during early season peak flows. Regression relationships (TSS versus Q) developed for the highest stormflows (> 1 m3/s) had steeper slopes than the lower stormflows (< 1 m3/s). Turbidity correlated well (r=0.94) with TSS for all storm-flow data combined. Organic matter constituted an average of 35 percent (by weight) of TSS for all water quality samples. 相似文献
896.
Jerry C. Ritchie J. Roger McHenry 《Journal of the American Water Resources Association》1985,21(1):99-104
ABSTRACT: The determination of sediment accumulation rates is important in understanding how these materials are affecting lakes and reservoirs ecosystems. In this study three methods were used to estimate sediment accumulation rates in the impounded backwater lakes behind Lock and Dam Nos. 8 and 9 on the upper Mississippi River. The three methods were: 1) a “spud” survey, 2) a survey of bottom contours, and 3) the use of fallout cesium-137. The field use of these three methods of determining sediment accumulation and the potential errors and merits involved in each method are discussed. The results from the field study in backwater areas along the upper Mississippi River showed the survey of bottom contour method gave the lowest rate of sediment deposition and the 137Cs method gave the highest rates. Sediment accumulation rates from 0 to 7.8 cm per year were measured in the study area. All three methods are useful and have unique characteristics for determining rates and patterns of sediment accumulation. Thus the choice of a method to be used in a sediment survey is dependent on the type of information needed and the time available. 相似文献
897.
三江平原典型沼泽湿地养分累积与沉积特征 总被引:4,自引:2,他引:2
研究了三江平原两类典型沼泽湿地(毛果苔草沼泽和芦苇沼泽)沉积物剖面有机碳、全氮、全磷和全硫的垂直分布规律,初步分析了三江平原湿地的沉积速率与沉积通量.结果表明,土壤有机碳、全氮、全磷和全硫在垂直方向上具有明显的分层和富聚现象,自上而下,有机碳的含量逐渐降低;全氮含量呈先增加后减少的分布趋势;毛果苔草沼泽全磷含量呈先减少后增加的"V"型分布,芦苇沼泽全磷含量逐渐降低;全硫的分布和有机碳的分布规律一致.相关性分析表明,全氮、全磷和全硫与有机碳之间呈极显著的正相关关系(P<0.01);有机碳与容重之间呈极显著的负相关关系(P<0.01).植被类型是影响沼泽湿地土壤有机碳、全氮、全磷和全硫的空间分布的主要因素之一.应用137Cs、210Pb测定沉积年代,并结合恒定放射性通量(CRS)模式推算年龄的结果表明,三江平原湿地平均沉积速率为0.33 cm·a-1,沉积通量为0.03~0.48 g·(cm2·a)-1,平均为0.29 g·(cm2·a)-1. 相似文献
898.
899.
900.
一株海洋假单胞菌产生物絮凝剂去除赤潮生物的实验研究 总被引:1,自引:0,他引:1
利用一株假单胞菌(Pseudomonas sp.)的发酵液研究了该细菌产絮凝剂对东海原甲藻和裸甲藻的絮凝去除作用.结果表明,该生物絮凝剂可有效絮凝去除实验所选用两种赤潮生物,并且随絮凝剂用量的增加以及作用时间的延长,去除效果逐渐增加至最大然后基本保持恒定.有效絮凝去除赤潮生物的体积浓度为4.0%~10.0%.有效絮凝作用时间为1.5 h左右,絮凝效率与体系的pH值密切相关,pH在8.0左右絮凝效率较高.不同浓度的Ca2+、Mg2+对该絮凝剂絮凝除藻作用有一定的增效作用, Ca2+、Mg2+的最佳助凝离子浓度分别为2.0 mmol/L及4.0 mmol/L. 相似文献