He Jun-hua, Cheng Yong-jin, Han Yan-ling, Zhang Hao, Yang Tao
The School of Mathematics and Physics, China University of Geosciences, Wuhan 430074, China.
Guang Pu Xue Yu Guang Pu Fen Xi. 2008 Aug;28(8):1870-4.
A method of spectral analysis, which can simultaneously detect dissolved organic matter (DOM) and chlorophyll a (Chl-a) in natural water, was developed in the present paper with the intention of monitoring water quality fast and quantitatively. Firstly, the total luminescence spectra (TLS) of water sample from East Lake in Wuhan city were measured by the use of laser (532 nm) induced fluorescence (LIF). There were obvious peaks of relative intensity at the wavelength value of 580, 651 and 687 nm in the TLS of the sample, which correspond respectively to spectra of DOM, and the Raman scattering of water and Chl-a in the water. Then the spectral fluorescence signature (SFS) technique was adopted to analyze and distinguish spectral characteristics of DOM and Chl-a in natural water. The calibration curves and function expressions, which indicate the relation between the normalized fluorescence intensities of DOM and Chl-a in water and their concentrations, were obtained respectively under the condition of low concentration(< 40 mg x L(-1))by using normalization of Raman scattering spectrum of water. The curves have a high linearity. When the concentration of the solution with humic acid is large (> 40 mg x L(-1)), the Raman scattering signal is totally absorbed by the molecules of humic acid being on the ground state, so the normalization technique can not be adopted. However the function expression between the concentration of the solution with humic acid and its relative fluorescence peak intensity can be acquired directly with the aid of experiment of fluorescence spectrum. It is concluded that although the expression is non-linearity as a whole, there is a excellent linear relation between the fluorescence intensity and concentration of DOM when the concentration is less than 200 mg x L(-1). The method of measurement based on spectral fluorescence signature technique and the calibration curves gained will have prospects of broad application. It can recognize fast what pollutants are and detect quantitatively their contents in water. It is realizable to monitor the quality of natural water with real time, dynamics and inlarge area.
为了实现对水质的快速定量监测，本文开发了一种能同时检测天然水中溶解有机物（DOM）和叶绿素a（Chl-a）的光谱分析方法。首先，利用激光（532nm）诱导荧光（LIF）测量了武汉市东湖水样的总发光光谱（TLS）。在该样品的TLS中，在波长580、651和687nm处有明显的相对强度峰，它们分别对应DOM光谱、水的拉曼散射以及水中Chl-a的光谱。然后采用光谱荧光特征（SFS）技术分析和区分天然水中DOM和Chl-a的光谱特征。通过对水的拉曼散射光谱进行归一化处理，在低浓度（<40mg·L⁻¹）条件下分别获得了水中DOM和Chl-a的归一化荧光强度与其浓度之间的校准曲线和函数表达式。这些曲线具有很高的线性度。当腐殖酸溶液浓度较大（>40mg·L⁻¹）时，拉曼散射信号被处于基态的腐殖酸分子完全吸收，因此不能采用归一化技术。然而，借助荧光光谱实验可直接获得腐殖酸溶液浓度与其相对荧光峰强度之间的函数表达式。结果表明，虽然该表达式整体上是非线性的，但当浓度小于200mg·L⁻¹时，DOM的荧光强度与浓度之间存在良好的线性关系。基于光谱荧光特征技术的测量方法和所获得的校准曲线具有广阔的应用前景。它能够快速识别水中存在哪些污染物并定量检测其含量。实现对天然水水质的实时、动态和大面积监测是可行的。
