Pollution Characteristics and Source Analysis of Heavy Metals in Soils in Yellow River Cultural Park Based on APCS-MLR and PMF Receptor Model

Abstract

With open spaces and good ecological environments, urban parks have become the first choice for the leisure and entertainment of many people. Therefore, the quality of park soil environments has gradually attracted the extensive attention of scholars. In this study, we take the Yellow River Cultural Park, a typical human disturbance area in the lower reaches of the Yellow River, as the research area to discuss the characteristics and sources of heavy metal pollution in the soil. Thirty-three soil surface samples were collected from the Yellow River Cultural Park, and the contents of seven heavy metals (Cr, Ni, Cu, Zn, Cd, Pb, and As) were determined using an inductively coupled plasma emission spectrometer (ICP-AES) and an inductively coupled plasma mass spectrometer (ICP-MS). The geo-accumulation index and geo-statistics method were used. Meanwhile, the absolute factor analysis-multiple linear regression (APCS-MLR) receptor model and positive matrix factorization (PMF) analysis model were employed to reveal the sources of soil heavy metals. The results showed that the average contents of heavy metals (Cd, Zn, Cu, Pb, and As) in the surface soil of the study area were 4.62, 1.78, 1.41, 1.08, and 1.03 times higher than the background values of soil elements in the tidal soil area of the lower reaches of the Yellow River, respectively. Except for Zn, the contents of other elements were lower than the corresponding values of soil elements in different regions along the Yellow River Basin. Among the seven heavy metal elements, the coefficients of variation of Cd and As were greater than 50%, showing obvious spatial variability. The decreasing trend of the accumulation index of the seven elements was Cd>Zn>Cu>Ni>Pb>As=Cr, and the element Cd belonged to the middle pollution category, which was obviously accumulated in the surface soil. The spatial distribution of heavy metals in the soil differed:the high contents of Cr, Cu, and Ni were distributed in the southwest and northeast, and the high-value areas of Cd and Pb were consistent with the areas of human activity intensity. The high-value areas of Zn and As were located in the center of lacustrine sediments. The combined results of the APCS-MLR and PMF models suggested that the first pollution source of soil heavy metal elements in the Yellow River Cultural Park could have been a natural source, the second pollution source may have been a transportation source, and the third source of pollution was judged as a mixed source. Human activities such as transportation sources and mixed sources were the main sources of heavy metal soil pollution, and Cr, Cu, and Ni were affected by natural factors. The contribution rates of APCS-MLR were 46.67%, 24.11%, 16.12%, and 13.10%, respectively, and the contribution rates of PMF were 35.50%, 35.48%, and 29.02%, respectively. This research can provide a basis for improving the ecological environment quality of the park and improving the health level of the population and can also provide support for the ecological environment risk management and comprehensive management along the Yellow River.