Effects of soils on laser induced fluorescence of BTX contaminated pore waters
Effects of soils on laser induced fluorescence of BTX contaminated pore waters
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DOI：
10.1061/(asce)1090-0241(1999)125:12(1072
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发表时间：
1999-12-01
影响因子：
3.9
通讯作者：
Hemond, HF
中科院分区：
文献类型：
--
作者：
Sinfield, JV;Germaine, JT;Hemond, HF
进行了实验室测试程序，以确定和解释影响土壤和地下水中的新的基于微芯片激光的荧光传感器的性能的基本因素。调查进行了使用一个多功能的实验装置，旨在模拟在原位的激光诱导荧光（LIF）传感器和污染的介质之间的接口，同时提供完整的控制测试条件。尝试隔离土壤性质，如粒度，土壤类型，颜色，矿物学和有机物含量在原位LIF观测的影响。试验结果表明，土壤对孔隙流体荧光寿命的测定或孔隙流体发射波长剖面的一般形式没有可测量的影响。然而，对于一个给定的污染物浓度在孔隙空间中的土壤具有狭窄的粒度分布，土壤粒度的减少伴随着减少所观察到的LIF信号的幅度和可变性。对于含有各种粒度的土壤，土壤中LIF观测主要受土壤中存在的最小颗粒的孔隙空间几何形状的影响。这些趋势被发现是在激光激发能量的直接路径中的土壤试样中的孔隙流体的体积的主要函数。土壤有机质含量和光学特性，如反射率也有潜在的影响，在土壤LIF观测，虽然在次要的基础上。在回顾这些实验结果，这表明土壤性质对荧光观测的相对影响，一个简单的几何模型，捕捉孔隙流体荧光观测土壤的主要影响。
A laboratory testing program was conducted to identify and interpret the fundamental factors affecting the performance of a new microchip-laser based fluorescence sensor in soil and ground water. Investigations were performed using a versatile experimental apparatus designed to simulate the in situ interface between the laser induced fluorescence (LIF) sensor and contaminated media while providing complete control of test conditions. Attempts were made to isolate the effects of soil properties such as grain size, soil type, color, mineralogy, and organic content on in situ LIF observations. Test results indicate that soil has no measurable effect on the determination of pore fluid fluorescence lifetimes or the general form of pore fluid emission wavelength profiles. However, for a given contaminant concentration in the pore space of a soil with a narrow grain size distribution, decreases in soil grain size are accompanied by a decrease in the magnitude and variability of observed LIF signals. For soils containing a wide range of particle sizes, in-soil LIF observations are primarily influenced by pore space geometry in relation to the smallest particles present in the soil. These trends were found to be a primary function of the volume of pore fluid in a soil specimen that is in the direct path of laser excitation energy. Soil organic content and optical characteristics such as reflectivity also have potential influence on in-soil LIF observations, although on a secondary basis. After reviewing these experimental results, which indicate the relative impact of soil properties on fluorescence observations, a simple geometric model is presented that captures the primary effects of soil on pore fluid fluorescence observations.