Abstract
Wetlands serve as significant sinks and sources of heavy metals. In this study, surface soil samples (0–25 cm) were collected from 15 sampling sites across the wetlands on the Ningxia, Henan,and the delta wetlands reaches to investigate the contents, distributions, and ecologic risks of heavy metals such as As and Cd in the wetland sediments in the Yellow River. The results revealed that the wetland soils in the upper and lower reaches were alkalineand more conducive to heavy metal enrichment. There was no significant spatial distribution pattern of the heavy metals across the wetlands in the Yellow River.The contents of the heavy metals decreased with increasing soil depth vertical profile each sampling sites. Geoaccumulation index (Igeo) analysis revealed that heavy metals had a negative Igeo value at each sampling site, expect for the following metals and sampling sites: in the Tianhe Bay wetland, the Igeo values for Cd, Mn, and Ni were 0.71, 0.17, and 0.04, respectively; in the middle reaches, the Igeo value for Cd was 0.28; and in the lower reaches, the Igeo value for Sb in the delta wetlands was 0.21.Pollution load index analysis and enrichment factor (EF) analysis revealed the occurrence of severe Cd contamination in the Ningxia, with an EF of greater than 3, indicating a high degree of anthropogenic impact. There was a strong correlation (correlation coefficient > 0.8) among the various heavy metals in the wetlands in both the Ningxia and delta wetlands, suggesting a common source for these elements.