2005～2018年北京平原区土壤汞时空特征及其影响因素

为了解北京平原区土壤汞的分布特征及变化规律,采样测定了2005、2015、2018年的土壤汞含量,获取了270条实验测试数据。采用定量与定性分析相结合的方式,阐述了土壤汞的时间和空间变化特征,并对影响土壤汞时空特征的因素进行了探讨。结果表明:北京平原区土壤汞含量整体呈下降趋势,2005～2015年由0.093×10^-6下降至0.064×10^-6,到2018年下降至0.058×10^-6,逐渐接近甚至低于北京市土壤背景值; 土壤汞的块基比为28.2%～29.9%,空间自相关性中等,空间结构受结构性因素和随机性因素的共同影响,在空间分布上呈现出“城区含量高、郊区含量低”的特点; 由于外界输入土壤内部的含汞物质大幅度降低(输入减少),以及土壤中的汞通过排放、转化、吸收等方式不断流失(输出持续),造成2005～2018年土壤汞含量不断下降; 工业生产、人类生活、城市建设历史等人为源加剧了城区土壤汞的富集,反映了随机性因素的影响; 水系流域、土壤质地等自然源造成土壤汞分布的局部性差异,反映了结构性因素的影响。

Tempo-spatial Characteristics of Soil Mercury in Beijing Plain,China from 2005 to 2018 and Their Influence Factors

In order to understand the distribution characteristics and variations of soil mercury in Beijing plain, the contents of soil mercury in 2005, 2015 and 2018 were sampled and measured, and 270 analytical data were obtained. A combination of quantitative and qualitative analysis was used to explore the tempo-spatial variation of soil mercury, and to analyze the influence factors affecting the tempo-spatial characteristics of soil mercury. The results show that the contents of soil mercury in Beijing plain decrease from 0.093×10^-6 in 2005 to 0.064×10^-6 in 2015, and to 0.058×10^-6 in 2018, which is close to or even lower than the soil background value in Beijing; the block-base ratios of soil mercury are 28.2%-29.9%, indicating that the spatial autocorrelation of soil mercury is moderate, and the spatial structure is affected by both structural and random factors; the spatial distribution of soil mercury in Beijing plain is characterized by “high content in urban areas, and low content in suburbs”; the mercury-containing substances imported from the outside into the soil are greatly reduced(input reduces), and the mercury in the soil is continuously lost through discharge, transformation and absorption(output continues), resulting in the continuous decline of the contents of soil mercury from 2005 to 2018; industrial production, human life, urban construction history and other human factors can aggravate the enrichment of mercury in urban soil, reflecting the impact of random factors; natural factors such as drainage basin and soil texture cause local differences in the distribution of soil mercury, reflecting the impact of structural factors.