煤矿区地下水中溶解性有机质荧光特征Ⅰ——含水层之间垂向差异

Fluorescence feature Ⅰ of the dissolved organic matters in the groundwater of mining area—the vertical difference of the aquifers

通过检测有机质含量和三维荧光光谱研究了霍州煤矿区地下水中溶解性有机质的垂向分布特征。结果表明,硝酸盐质量浓度在地表水和第四系水中较高(>37.41 mg/L),而在深部含水层(太灰和奥灰)基本未检出。地表水中TOC(总有机碳)质量浓度和UV254分别大于5.11 mg/L和0.146 cm-1;氧化还原作用下,第四系水中TOC质量浓度和UV254分别减小82.23%和97.96%,而深部含水层中TOC质量浓度也有降低。人类活动污水的大量排放导致地表水中Ⅱ区和Ⅳ区的荧光峰强度异常高,均大于等于8 245 QSU,Ⅲ区的荧光峰强度大于3 419 QSU;进入第四系含水层,Ⅱ区、Ⅲ区和Ⅳ区荧光峰强度均减少至216 QSU以下;太灰水和奥灰水中只Ⅱ区和Ⅳ区出现荧光峰,且荧光峰强度与TOC相关性不大;溶解性有机质(DOM)荧光峰强度与地下水流向呈负相关,同一煤矿区奥灰水中Ⅳ区的荧光峰强度比太灰水高。总体上,分析溶解性有机质含量和荧光特性、硝酸盐含量,可以从垂向上建立霍州矿区各含水层(体)的水化学特征。

We have adopted the method of the three dimensional fluorescent spectroscopy and analyzed the relation of the dissolved organic matter（ DOM） and nitrate concentrations in hoping to grasp the changing regularity of DOM quantitatively in vertical direction. The results of our study show that the concentration of the nitrate tends to be rather high both in the surface water and quaternary water（ 37. 41 mg / L）. However,no content of nitrate has been detected in the deep aquifers,which can probably be attributed to the fact that the nitrate can be fully directed to degrade more thoroughly. On the other hand,in the surface water,the concentration of the total organic carbon（ TOC） and the value of UV254 are greater than 5. 11 mg / L and 0. 146 cm- 1,respectively.That is to say,the concentration of DOM proves to be comparable with that of the rural secondary effluent,which indicates that the water quality of Fenhe River had been to some extent polluted by the industrial production and the human activity. Further study shows that,the concentration of TOC works out at 17. 74% and UV254 value tends to be 2. 04% of those of the surface water in the quaternary water by oxidation-reduction reaction. However,in the deep aquifers（ including the limestone water formulated in Ordovician and Taiyuan）,the concentration of TOC in Taiyuan formation limestone water tend to be 53. 13%-57. 00% of that in the quaternary water,and UV254 tends to be lower than the detection limit. Furthermore,we have found that there exists a good linear correlation between the concentration of TOC and the value of UV254 in the vertical distribution（ R2= 0. 983 2）. The fluorescence intensity（ FI） values of region Ⅱ and region Ⅳ prove to be greater than 8 245 QSU in the surface water due to the discharge of waste water,whereas that（ FI） of region Ⅲ equals 3419-4 189 QSU. After infiltrating into the quaternary aquifer,the fluorescence intensities of region Ⅱ,region Ⅲ and region Ⅳwould be degraded to 215. 1 QSU,187. 4 QSU and 145. 3 QSU,respectively. And we could find the fluorescence peaks of regionⅡ and region Ⅳ in Taiyuan formation limestone water and Ordovician limestone water. The correlation between FI and the concentration of TOC turns out low,but the correlation between FI and direction of groundwater flow proves negative by nature. What is more,FI of region Ⅳ in Ordovician limestone water tends to be greater than that in Taiyuan formulated limestone water from the same coal mine. Thus,it can be seen that the content and fluorescence characteristic features of DOM could be used to determine the groundwater chemical feature of all kinds of aquifers in Huozhou mining area.