Objective The aim of this study was to elucidate the distribution characteristics, pollution levels, and sources of heavy metals in farmland soils throughout Henan province.

Method Based on bibliometric and field testing methods, a total of 105 sampling points were obtained, corresponding risk screening and control values in the 《Soil Environmental Quality Agricultural Land Soil Pollution Risk Control Standard (Trial)》(GB 15618−2018) as the basis for evaluating heavy metal pollution in agricultural soil. Based on a large amount of literature data, the land accumulation index method, potential ecological risk index method and principal component analysis method were used to study the pollution characteristics, distribution characteristics, ecological risks and main sources of heavy metals in farmland soil in Henan province.

Result The average contents of Pb in western and northern Henan were higher than those of the screening value, while the average contents of Cd in eastern, southern, western, and northern Henan were higher than those of the screening value. The average contents of Cu, Zn, As, Ni, and Cr were all lower than the screening value, except for Ni. They were all higher than the soil background value in Henan Province. The exceeding rates of heavy metals of Pb, Cu, Cd, Zn, As, Ni, and Cr in farmland soil in Henan province are 21.51%, 11.84%, 43.82%, 6.67%, 8.06%, 3.85% and 6.17%, respectively. Key areas such as Jiyuan, Xinxiang, and Jiaozuo needed to be given special attention. From the perspective of geo-accumulation index(I_geo), the average values of Cu, Zn, As, Ni, and Cr belonged to non-pollution, while Cd and Pb had the highest degree of land accumulation pollution, with I_geo mean values of 1.65 (medium pollution) and 0.39 (light to medium pollution), respectively. Of all the heavy metals, Cd had extremely strong potential ecological risks. In different regions, the potential ecological risk level in northern Henan was extremely strong, while the potential ecological risk level in western Henan was strong and required special attention. Heavy metal sources varied across different regions of Henan province. The eastern region of Henan province was dominated by traffic and agricultural-natural mixed sources. The southern Henan region was characterized by natural, agricultural, and industrial sources. The western Henan region was primarily agricultural-natural mixed and industrial sources. The northern Henan region was mainly industrial and agricultural sources. The central Henan region was influenced by industrial-natural mixed and traffic sources.

Conclusion Heavy metal pollution in farmland in Henan is generally controllable, but the sources of heavy metals are relatively complex, and the pollution level in the western and northern regions of Henan is greater than that in other regions, especially the pollution of Cd and Pb, which requires long-term and focused tracking and research. In response to the current situation of soil pollution in farmland in Henan province. It is recommended to adhere to source management, optimize industrial layout, adjust planting structure, and strengthen policy funding for basic research, in order to provide theoretical support for the prevention and control of heavy metal pollution in farmland in Henan province, and will expedite the achievement of environmentally friendly and sustainable agricultural development.