摘要
以沈阳市5条黑臭水体作为研究对象,其中支流I和支流II为重度黑臭,支流III、IV和V为轻度黑臭。运用三维荧光光谱结合平行因子方法对黑臭水体中水溶性有机物(DOM)组分进行了表征,并通过与光谱数据相结合的方法,建立了DOM各组分最大荧光强度(F_(max))与归一化遥感反射率的一元线性回归方程。三维荧光分析结果显示,DOM分为2个类别3种不同组分,分别为类蛋白荧光组分C1(235nm/360nm)、类腐殖质荧光组分C2(220nm/430nm)和C3(255nm/520nm)。水体光谱分析结果表明:在250~800 nm处,有色可溶性有机物吸收系数(a_g)、总悬浮物吸收系数(a_p)曲线均随着波长的增大逐渐减小,空间变化特征明显;在特征波长440 nm处,轻度黑臭水体的有色可溶性有机物吸收系数总体上大于重度黑臭水体,重度黑臭水体总悬浮物吸收系数总体大于轻度黑臭水体。与正常水体相比,在可见光波段,沈阳市黑臭水体遥感反射率普遍较低,出现3个反射峰和1个反射谷。但支流I与其他黑臭水体不同,表面呈白灰色,导致其遥感反射率(R_(rs))呈现与正常水体类似的明显的波峰和波谷,是一类特殊的黑臭水体。线性回归分析表明,由归一化遥感反射率比值R_(688)/R_(555)与DOM组分最大荧光强度所建立的线性模型估算精度最理想。R_(688)/R_(555)与轻度黑臭水体DOM组分F_(max)的拟合程度好于重度黑臭水体。进一步研究表明,R_(688)/R_(555)与色氨酸类物质拟合程度较好,与腐殖质类物质没有明显的线性关系。
In this study, 5 typical black-odorous water bodies in Shenyang city were selected as object, and tributaries I and II were severe black-odorous ones, tributaries III, IV and V were mild black-odorous ones.Excitation-emission matrix(EEM) fluorescence spectroscopy combined with parallel factor analysis(PARAFAC)was employed to analyze the components of dissolved organic matter(DOM). Combining water spectral data, a univariate linear regression equation between the maximum fluorescence intensity(F_(max)) of DOM components and normalized remote sensing reflectance was obtained. The EEM analysis results showed that DOM was decomposed into three components by PARAFAC, including protein-like component C1(235 nm/360 nm), fulviclike component C2(220 nm/430 nm) and humic-like component C3(255 nm/520 nm). Water spectral data showed that the absorbance coefficient(a_g) of colored dissolved organic matter and absorbance coefficient(ap)total suspended matter absorption curves decreased with the increase of wavelength from 250~800 nm, which had an remarkable spatial variation characteristic. At the characteristic wavelength of 440 nm, agvalues of mild black-odorous water bodies were larger than those of severe black-odor water bodies, but apvalues of severe black-odor water bodies were lower than those of mild black-odorous water bodies. Compared with normal water body, the remote sensing reflectance of black and odorous water bodies in Shenyang city was generally lower,with 3 reflection peaks and 1 reflection valley within visible spectrum. However, tributary I was different from others, its surface was white-gray, which results in the obvious peaks and valleys in its remote sensing reflectance(R_(rs)) similar to normal water bodies, it was a special kind of black and odorous water body. The results of linear regression analysis showed that the linear model between the normalized reflectance ratio R_(688)/R_(555) and the maximum fluorescence intensity of DOM components had the best estimation accuracy. The fitting results between R_(688)/R_(555) and F_(max) of mild black and odorous water bodies were better than those of severe black and odorous water bodies. Further studies showed that R_(688)/R_(555) fitted well with tryptophan, but had no obvious linear relationship with humus.
引文
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