深圳市土壤砷的背景含量及其影响因素研究

为摸清深圳市土壤砷的背景含量现状，以全市不受或很少受人类活动影响的基本生态控制线区域作为调查范围，布设土壤表层样点450个、土壤典型剖面样点50个，采用多点增量采样法采集表层样品500个、深层样品100个.结果表明，深圳市表层土壤砷的背景含量范围为0.07~202mg/kg，算术平均值为11.3mg/kg，95%分位值为55.9mg/kg，显著高于“七五”深圳土壤环境背景调查结果砷的95%分位值（35.4mg/kg）.不同土类中赤红壤、红壤和黄壤砷背景含量的算术平均值相近，95%分位值的高低顺序为：红壤 > 赤红壤 > 黄壤.不同母质母岩发育的土壤砷背景含量的算术平均值高低顺序为：灰色灰岩 > 砂砾页岩 > 凝灰熔岩 > 变质岩 > 花岗岩 > 片麻岩，95%分位值的高低顺序为：灰色灰岩 > 砂砾页岩 > 凝灰熔岩 > 变质岩 > 片麻岩 > 花岗岩.不同剖面层次砷背景含量的平均值和95%分位值差异较大，高低顺序为：底层 > 中层 > 表层，随着深度增加，砷的背景含量逐渐增加.土壤pH值、砂粒含量与砷背景含量呈显著负相关，黏粒、粉粒含量与砷背景含量呈显著正相关.土壤母质母岩和机械组成是影响深圳市土壤砷背景含量的主要因素.研究结果可为南方典型区域砷的土壤环境背景值研究提供参考与借鉴.

Study of soil background content of arsenic and its impact factors in Shenzhen

In order to find out the soil background content of arsenic in Shenzhen, 450 soil surface sample points and 50 typical soil profile sample points were set up in the area of basic ecological control line which was not or rarely affected by human activities. 500 surface samples and 100 deep samples were collected by multi-point incremental sampling method. The results showed that the background content of arsenic in the surface soil was 0.07~202mg/kg, the arithmetic average value was 11.3mg/kg, and the 95% fraction value was 55.9mg/kg, which was significantly higher than the 95% fraction value (35.4mg/kg) of Shenzhen soil environmental background survey during the seventh five-year plan. The arithmetic average values of background content of arsenic in lateritic red soil, red soil and yellow soil were similar in different soil types, and the order of 95% fraction values were red soil > lateritic red soil > yellow soil. The order of arithmetic average of arsenic in different parent rocks were grey limestone > gravel shale > tuff lava > metamorphic rock > granite > gneiss, and the order of 95% fraction values were grey limestone > gravel shale > tuff lava > metamorphic rock > gneiss > granite. The average and 95% fraction values of arsenic in different section layers were quite different. The order of arsenic content were bottom layer> middle layer > surface layer. With the increase of depth, the soil background content of arsenic gradually increased. Soil pH and sand content were negatively correlated with background content of arsenic, while clay and silt content were positively correlated with background content of arsenic. Soil parent rock and mechanical composition were the main factors that affected the soil background content of arsenic in Shenzhen. The results could be provide reference for the study of soil environmental background value of arsenic in typical regions of South China.