| 基于透射光法探讨水流流速对DNAPL运移分布的影响 |
| 摘要点击 1728 全文点击 875 投稿时间：2014-12-10 修订日期：2015-03-16 |
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| 中文关键词 重非水相 饱和多孔介质 透射光法(LTM) DNAPL饱和度 空间矩 地下水流速 |
| 英文关键词 DNAPL saturated porous media light transmission method DNAPL saturation spatial moments water flow velocity |
| 作者 | 单位 | E-mail | | 高燕维 | 南京大学地球科学与工程学院水科学系, 表生地球化学教育部重点实验室, 南京 210023 | gordon.wolf@foxmail.com | | 郑菲 | 南京大学地球科学与工程学院水科学系, 表生地球化学教育部重点实验室, 南京 210023 | | | 施小清 | 南京大学地球科学与工程学院水科学系, 表生地球化学教育部重点实验室, 南京 210023 | | | 孙媛媛 | 南京大学地球科学与工程学院水科学系, 表生地球化学教育部重点实验室, 南京 210023 | | | 徐红霞 | 南京大学地球科学与工程学院水科学系, 表生地球化学教育部重点实验室, 南京 210023 | hxxu@nju.edu.cn | | 吴吉春 | 南京大学地球科学与工程学院水科学系, 表生地球化学教育部重点实验室, 南京 210023 | jcwu@nju.edu.cn |
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| 中文摘要 |
| 重非水相污染物(DNAPL)在地下水中的运移分布受多种因素控制. 选择四氯乙烯(PCE)作为DNAPL的代表,通过二维砂箱实验探究地下水流速对DNAPL运移分布的影响. 采用透射光法(LTM)监测DNAPL在砂箱内的运移行为并定量分析DNAPL的饱和度,进而采用空间矩分析DNAPL污染羽的平均运移行为随时间的变化. 结果表明,透射光法分析得到的DNAPL计算体积与实际注入体积有良好的相关性(R2>0.98),LTM的测量精度较高,可准确反映DNAPL的入渗行为和再分布过程. DNAPL饱和度和污染羽一阶矩(质心)的分析结果表明,流速的增加能够促进DNAPL在水平和垂直方向的运移使得运移路径倾斜,且其对DNAPL垂向入渗的促进作用更为明显; 污染羽二阶矩(展布)的分析结果显示流速的增加还提高了DNAPL在横向和垂向的扩散速度,导致污染区域增大. 实验过程中,DNAPL的饱和度直方图在较小地下水流速下始终呈单峰分布,在较大地下水流速下则逐渐呈双峰分布,且流速越大,两个峰值的间距越大. |
| 英文摘要 |
| The migration and distribution of dense non-aqueous phase liquid (DNAPL) in subsurface are affected by many factors. We selected PCE as the substitute contaminant, and performed several well-controlled two-dimensional sandbox experiments to investigate the effect of flow velocity on DNAPL infiltration and redistribution. Light transmission method (LTM) was used to monitor the transport process of DNAPL in the sandbox and quantitatively measure DNAPL saturation. The spatial moments based on measured DNAPL saturation were used to describe the average spatial behavior of DNAPL plume at various times. Experimental results showed a strong correlation between results obtained by LTM and the known amounts of DNAPL added into the sandbox (R2>0.98). The LTM accurately reflected the infiltration and redistribution processes. The results of DNAPL saturation and first moment (mass center) showed that the increased velocity promoted not only lateral but also vertical migration, leading to an inclined percolation path. Also vertical migration reacted more sensitive to flow velocity. The second moment (spread variance) showed that the increased velocity promoted lateral and vertical spread, increasing the pollution scope. The histogram of DNAPL saturation showed a unimodal distribution at low flow velocity, but showed a bimodal distribution at lager flow velocity, and the distance between two peaks became higher with the increasing flow velocity. |
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