Analysis and pollution evaluation of heavy metal content in soil of the Yellow River Wetland Reserve in Henan

Objective This study aims to assess the contamination levels of six heavy metals, namely arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), mercury (Hg), and lead (Pb), in the soil of the Henan Yellow River Wetland Reserve. It seeks to reveal the spatial distribution and trends of heavy metal pollution, providing a scientific basis for the rational utilization and effective protection of soil. Additionally, it aims to propose targeted management and remediation recommendations to mitigate or prevent soil pollution. Method A total of 706 soil samples were collected in this area in combination with the land use type map. As and Hg were determined by atomic fluorescence spectrometry, and Cr, Cu, Pb and Cd were determined by inductively coupled plasma mass spectrometry. Taking the soil pollution risk screening value of agricultural land (GB15618-2018) as a reference value, the sample data were statistically analyzed, and the Nemerow comprehensive pollution index method combined with ArcGIS technology was used to evaluate the soil environmental quality. Result The comprehensive pollution index of the soil in the Yellow River Wetland Reserve was 0.42, ranging from 0.17 to 2.38, which was safe and not polluted (I grade). Out of 706 sampling locations, 674 remained uncontaminated, while 26 exhibited cleanliness. Although they were in the warning line, they did not exceed the standard, accounting for 3.68% of the total number of sampling points. Five sample points were slightly polluted, accounting for 0.71% of the total sample points, and one sample point was moderately polluted, accounting for 0.14% of the total sample points. It can be seen that there are few agricultural land pollution points in the Yellow River Wetland Reserve, and the soil environment quality is generally good. Conclusion The soil in the Yellow River Wetland Reserve in Henan has a very small amount of mild and moderate pollution, and there is no severe pollution. The cleanliness is currently high.