摘要
本文分别采用斯托克斯沉降速率公式和重复深度吸管法计算了2005年4月、5月间在太湖进行的四次静沉降模拟实验中的沉降速度．结果表明：1)太湖水体中悬浮物的沉降属于絮凝沉降．2)水体中悬浮物浓度与沉降时间均呈现出明显的指数衰减规律(R^2＞0．80),悬浮物中无机物含量较高时这种规律更为明显(R^2≥0．99)．3)悬浮物浓较低时,太湖悬浮物的沉降速率与水体中的悬浮物浓度无明显的相关关系；而悬浮物浓度较高时,沉降速率随悬浮物浓度升高而增大．经拟合沉降速度(ω)与悬浮物浓度(C)之间符合Logistic曲线ω=0．021/(1+exp(-0．026(C-166．3))),R^2=0．98,n=54．4),斯托克斯公式可用来粗略估算太湖悬浮物的沉降速率,而重复深度吸管法则适合于较精确地计算太湖悬浮物的沉降速率．但在计算时须注意根据悬浮物的特性,选取其特征沉降速率．本文计算得到的太湖悬浮物的沉降速率范围为0．002 cm/s-0．005 cm/s．
Four experiments were conducted in laboratory for hydrostatic settling behavior of suspended matter in Lake Taihu in April and May, 2005. The settling velocity of suspended matter was calculated by both Stokes equation and McLaughlin method, and the results were further compared. The results showed that settlement of suspended matter in Lake Taihu was flocculation settlement. It also showed that the suspended matter concentration decayed exponentially with time, which was more obvious when the percentage of inorganic suspended matter accounting for total suspended matter was higher （ R^2≥0.99 ）. When the suspended matter concentration was low, no clear relationship was found between settling velocity and suspended matter concentration. But settling velocity obviously rose with the increase of suspended matter concentration while the latter was high. Based on the data of four hydrostatic experiments, it was found that settling velocity （ω） of suspended matter and suspended matter concentration （C） fitted in Logistic Curve ω =0.021/（ 1 ＋ exp（-0.026（ C-166.3））） ,R^2=0.98 , n=54. Comparing two calculation methods, Stokes equation could be used to estimate the settling velocity, but the calculation result was more accurate using Mclaughlin method. The settling velocity of suspended matter estimated in Lake Taihu ranged from 0.002 cm/s to 0.005 cm/s.
出处
《湖泊科学》
EI
CAS
CSCD
北大核心
2006年第5期528-534,共7页
Journal of Lake Sciences
基金
国家自然科学基金项目(40573062)
国家重点基础研究发展计划项目(2002CB412305)联合资助.
关键词
悬浮物
静沉降
沉降速度
太湖
suspended matter
hydrostatic settling
settling velocity
Lake Taihu
