川中典型丘陵区土壤砷和汞空间变异特征及影响因素分析

Spatial Variability Characteristics and Influencing Factors of Soil Arsenic and Mercury in the Typical Hilly Region of Central Sichuan,China

采集耕层(0～20 cm)土样325个,在ArcGIS9.0平台上运用地统计学方法研究川中典型丘陵区土壤中砷和汞含量的空间变异特征及其主要影响因素。结果表明,研究区土壤砷和汞含量分别为(8.57±0.175)mg.kg-1和(0.078±0.067)mg.kg-1,均未超过国家土壤环境质量一级标准。土壤砷含量在空间上整体呈环状分布,以西北部云绣-赵镇一带和中东部黄家乡-三溪-金龙一带呈现出2个高值中心(>10.5 mg.kg-1),并由这两个中心向北部和东南部两侧逐渐降低。汞含量整体也呈环状分布,但局部出现斑点、块状区域,高值中心(>0.090 mg.kg-1)有4处,分别位于赵镇、西沟、白果及淮口附近,汞含量沿中心区向两侧逐渐递减。影响因素分析表明,土壤砷和汞含量总体呈现出灌溉水田最高,疏林地最低的特点。不同土壤质地间砷、汞含量差异显著,砷含量在粘土(10.09±2.93 mg.kg-1)中最高,汞含量在中壤土(0.112±0.120 mg.kg-1)中最高。此外,土壤pH值与砷、汞含量呈显著负相关关系,而土壤有机质与二者均呈极显著正相关关系。

The heavy metal accumulation in soils has become a potential threat.Understangding spatial variability and influencing factors of soil heavy metals is an important precondition for safety in agricultural production.325 random sampling points in topsoi（l0～20 cm）from the typical hilly region of Central Sichuan were assembled for testing the content of As and Hg,and geostatistical methods were used to analyzed their spatial distribution.The results showed that the average contents of As and Hg were（8.57±0.175）mg.kg-1 and（0.078±0.067）mg.kg-1,respectively.And the contents of heavy mental were lower than the soil threshold levels of the GradeⅠcriteria for the Chinese environmental quality standard.The highest value regions（10.5 mg.kg-1）of As mainly distributed in northwest and middle-eastern area,then reduced gradually towards north and southeast,presenting annular distribution on the whole.While the lowest value regions（6.5 mg.kg-1）located in southeast part of study area.Relatively,the distribution pattern of Hg was more complicated.There were four highest value regions（0.09 mg.kg-1）and mainly distributed in northwest,east and southwest.Taking the highest part as the center,the Hg content decreased towards northwest and southeast.On the other hand,the lowest value regions（0.045 mg.kg-1）were situated in southwest and middle-eastern area.The distribution of soil As and Hg was influenced by land use types,soil texture,soil pH and organic matter（OM）.In different land use types,the content of As and Hg were highest in paddy field and lowest in woodland.The content of As and Hg in soil had significant difference with soil texture.The contenf of As was highest in clay（10.09±2.93 mg.kg-1）and Hg was highest in loam（0.11±0.12 mg.kg-1）.Additonally,the content of As and Hg exhibited significant negative correlation with soil pH and remarkable positive correlation with soil OM.