The Ecological Risks of Heavy Metals in the Estuarine Wetland Ecosystem and Their Impacts on Human Health: A Case from Yellow River Delta National Nature Reserve, China

Nature reserves are integral to sustaining ecological balance, functioning like a precise ecological regulator, where various species depend on and constrain one another to collectively form a stable ecosystem. Nevertheless, in the wake of economic development, pollutants like heavy metal contamination have insidiously emerged, imperceptibly influencing all these processes. To understand the ecological risk of heavy metals in an estuarine nature reserve, this study focused on the Yellow River Delta Nature Reserve (YRDNNR) and analyzed the distribution, potential environmental risks, and possible sources of heavy metals (Mn, Cu, Zn, Cr, As, Cd, Pb) in the surface sediments of this region. The results indicated that YRDNNR was rich in As and Cd, with Cd presenting the most substantial ecological risk. Further analysis suggested that the high levels of As and Cd could be ascribed to agricultural activities. This study also found that agricultural practices have made a significant contribution to the carcinogenic risk and pose certain risks to the natural environment and human health. More in-depth monitoring and testing of As and Cd levels in YRDNNR should be carried out, and measures should be adopted in accordance with their development. Moreover, the systematic regulation of fertilizer and pesticide use, along with enhancements to farmers’ ecological awareness, is of great significance to alleviating pollution hazards. The findings of this study carry significant implications for the ecological conservation of coastal wetlands, serving as a critical alert to the potential proliferation of heavy metal contamination in other areas of the delta.