乌达煤田地表汞交换通量研究

Study on surface mercury exchange flux in Wuda Coalfield

地表汞释放被认为是大气汞的主要来源之一。我国拥有世界上总面积最大的煤矿区,但对煤矿区地表汞释放的研究鲜有报道。采用通量箱与RA-915+测汞仪联用法对具煤火发育的乌达煤矿区地表汞交换通量进行了测试。测试结果显示:背景区地表汞交换通量值为4~29ng/(m^2·h),均值为19ng/(m^2·h);无火区地表汞交换通量值为14~62ng/(m^2·h),均值为32ng/(m^2·h);火区地表汞交换通量值为80~318ng/(m^2·h),均值为177ng/(m^2·h)。煤矿区地表汞交换通量值显著高于背景区,并且部分汞可能直接来源于地下煤火,地表汞释放可作为认识地下煤火发育状况的有效途径。通过分析地表汞交换通量与自然条件相关性,发现汞交换通量与光照强度、地表温度存在显著正相关性。矿区白天大气汞含量受地表汞释放影响。

As an important atmospheric mercury source,the mercury emission fluxes from soil has been paid more and more attentions. China has largest area of coalfield in the world,but data of Hg flux from coalfield are serious limited,especially,with coal fire occur.In the study,Hg fluxes in coalfield were measured using the dynamic flux chamber(DFC) method,coupled with a Lumex multifunctional Hg analyzer RA-915+.The results show that the Hg flux in Wuda coalfield range from 4 to 318 ng/(m^2 · h),and the average value in different area were different,such as fire area( b,177 ng/(m^2 · h)),no fire area( c,32 ng/(m^2 · h)),and background value( a,19 ng/(m^2 · h)). Hg emission still continue from underground coal seam,even if there was no phenomenon of coal-fire on soil surface such as no vents,no crack,and no smog.This phenomenon occur in all type areas including coal-fire area,no coal-fire area,and back-filling area,which is universal in Wuda Coalfield.Hg flux may offer a new way to know the oxidative state of the underground coal.The Hg emission flux was found to be positively correlated with soil surface temperature and solar radiation and negatively correlated with relative humidity.The atmosphere Hg content was effected by soil surface emission Hg in Wuda Coalfield in daytime.