# Risk Assessment and Source Apportionment of Heavy Metals in Soils from Handan City
## 1 Introduction  
Soil security is significant for food safety and public health [1]. With the speedy development of the economy, the emission of pollutants by water, atmospheric deposition, and rain leaching quicklyheavy metal in soil. The Igeo was introduced by [PERSON], and used to identify the metal contamination. Contamination factor (CF) is the ratio of the concentration of a metal in the soil to background levels and PLI is used to assess the pollution degree of heavy metal in the study area. NIPI is useful tool for the comprehensive assessment of the degree of soil pollution. The ecological risk index (RI) considers the synergistic effect of heavy metal concentrations and toxic reactions, and links the ecological effects caused by heavy metal pollution with toxicology [17]. [PERSON] et al. (2019) used several methods, such as CF, Igeo, PLI, NIPI, RI and RAC, to evaluate heavy metal pollution in sediments from reservoirs of the Olt River, which found that As was the most pollution-heavy metal in the Olt River lakes [4]. The health risk of soil heavy metals to the human body is mainly evaluated by the model recommended by EPA [7; 18; 19], including the carcinogenic risk and non-carcinogenic risk of heavy metals, by quantitatively calculating exposure by ingestion, skin contact and inhalation.  
In the natural environment without anthropogenic disturbance, heavy metal contents in soil are at very low levels. However, some heavy metals accumulate in soil due to human inputs [12], such as industrial emissions, coal combustion, mining exploration, vehicle emissions, waste incineration and agriculture activities, etc. [20; 21]. At present, the research on the source of heavy metals mainly includes source identification and source apportionment [8; 22; 23; 24]. Source identification is mainly used to qualitatively determine the source of pollutants, such as correlation analysis, cluster analysis, PCA and other methods [22; 25]. Source apportionment can not only determine the main pollution sources, but also quantify the contribution of pollution sources [10]. At present, the most common source-apportionment methods for heavy metals include the chemical mass balance (CMB) model [26], positive matrix factor (PMF) model [27], UNMIX model [28], the absolute principle-component scores multiple linear regression (APCS-MLR) model [29], etc. The PMF model recommended by EPA can guarantee non-negative factor distribution and contribution and deal with the missing and inaccurate values [12]; therefore, it is extensively used in the quantitative apportionment of pollutant sources [30; 31].  
Handan is a heavy industrial city, known as the \"steel capital\", with developed transportation. Several human activities can cause heavy-metal soil contamination. The contents of seven heavy metals in Handan soil were investigated. Pollution index (PI), Geoaccumulation index (Igeo), Nemerow integrated pollution index (NIPI) and pollution load index (PLI) were applied to assess heavy-metal soil pollution. The ecological risk and health risk was evaluated according to these methods. In addition, SPSS software was used for correlation analysis, cluster analysis and principal component analysis to identify heavy-metal pollution sources, and the PMF model was used to quantitatively analyze pollution sources. This study was significant to grasp the spatial distribution, pollution status, ecological risk, health risk and main pollution sources of heavy metals in Handan city. According to the analysis of pollution sources, effective measures were taken to reduce the level of heavy-metal pollution in soil.