煤矿区地下水中溶解性有机质荧光特征Ⅱ——深部含水层分布特征

Fluorescence feature of dissolved organic matters in groundwater of mining area-Ⅱ.Distribution features in the deep aquifers

为研究霍州矿区深部含水层中溶解性有机质地层差异及其迁移转化机理,通过三维荧光光谱(3DEEM)、TOC和硝酸盐质量浓度综合分析了溶解性有机质(DOM)的含量和分布特征。结果表明,深部含水层中溶解性有机质和硝酸盐质量浓度均较低,其中TOC(总有机碳)质量浓度小于0.6 mg/L、NO_3^-N质量浓度小于1.6 mg/L。太灰水和奥灰水中主要出现了Ⅱ区的色氨酸类荧光峰和Ⅳ区的溶解性微生物代谢产物荧光峰,其中色氨酸类荧光峰强度随着地下水流向而逐渐降低,溶解性微生物代谢产物荧光峰强度在李雅庄矿和辛置矿出现了一定异常。生物源指数(BIX)和腐殖化指数(HIX)表明深部含水层中DOM来源于生物或水生细菌,且具有较好的溯源一致性;荧光指数f_(470/520)比f_(450/500)更能说明DOM中腐殖质组分的来源,且f_(470/520)较大(>2.1),表明深部含水层中DOM来源于生物,且腐殖类物质芳香性较弱,含有的苯环结构较少。太灰水中TOC、色氨酸类荧光峰强度和溶解性微生物代谢产物荧光峰强度均与硝酸盐质量浓度呈负相关,且线性拟合的相关度较高;奥灰水中相关性则较差。

The paper is aimed at pursuing the concentration and feature variations of the dissolved organic matters（DOM） with the hydrogeological condition and groundwater flow in all groundwater.In order to identify the composition and distribution of DOM in the deep aquifers of Huozhou mining area,we have made an analysis and exploration of the three dimensional excitation emission matrix（3DEEM）,DOM and nitrate concentrations of our investigation,which indicates that there do not seem to be any obvious difference for pH value（7.0 8.5） in both Taiyuan formation limestone water and Ordovician limestone water.The concentrations of NO3^-- N prove to be 00.4 mg/L and 0.01 1.59 mg/L in Taiyuan formation limestone water and Ordovician limestone water,respectively.What is more,we have found that,whereas the variation regularity of DOM tends to be obviously different in the two aquifers,the TOC displays a decreasing trend with Taiyuan formation limestone water flowing,though TOC indicates an increasing trend next with Ordovician limestone water flowing.Furthermore,the mass concentrations of DOM and nitrate turn out lower（TOC 0.6 mg/L and NO3^-- N 1.6mg/L）.In addition,we have also found that there may exist two fluorescence peaks both in Taiyuan formation limestone water and Ordovician limestone water,including region Ⅱ（i.e.the tryptophan）and region Ⅳ（i.e.the soluble microbial by-product-like）.Talking to the fluorescence intensity（FI） of region Ⅱ,we have found that it grows less in the groundwater flowing direction,while FI values in region Ⅳ in Liyazhuang mine and Xinzhi mine prove to be quite different from other mines.The BIX and HIX test indicates that DOM enjoys a biological or aquatic bacterial origin in the deep aquifers,and the two excitation emission matrix（EEMs） parameters turn out to be well in accord with the origin;f（470/520） is likely to determine the origin of humus better than f（450/500）.The higher value of f（470/520） may also indicate that DOM may enjoy a biological source in the deep aquifers.The aromatic structures of humic-like compounds prove to be slackened,and organic compounds with benzene rings may get decreased.Nevertheless,DOM may not be easy to get reacted with nitrate for the low concentration,with the high negative correlation among nitrate and TOC and FI in Taiyuan formation limestone water,and the lower correlation in Ordovician limestone water.Therefore,it would be possible that the three dimensional excitation emission matrix and DOM concentrations could be used to study the groundwater flow and hydrogeochemical characteristics difference.