Ecological risk transmission network and its response characteristic in heavy metal-contaminated soil ecosystem under...

The previous studies still remain limited regarding the transmission mechanism of heavy metal contaminated ecological risk. This study develops an information network analysis-based ecological risk assessment framework (INA-ERA) for As and Ni in soil ecosystem under stringent and lenient environmental constraints. The response characteristic between heavy metal concentration and ecological risk is illustrated by the Long Short-Term Memory (LSTM) multi-objective regression prediction model. Three representative contaminated industrial sites in Cangzhou of Hebei Province in China are given for validating the INA-ERA framework's effectiveness. Results reveal that heavy metals can be categorized into three components according to source apportionment: Factor 1 (Hg 65.4 % and Cd 48.8 %) from industrial production, Factor 2 (Cu 43.1 % and Pb 41.7 %) linked to vehicular emissions, and Factor 3 (As 58.1 % and Ni 42.8 %) influenced by natural-industrial mixed sources. Carcinogenic risk mainly comes from As and Ni especially for children, exceeding the minimum threshold (10^-6) in most areas. Soil microorganisms have a high degree of association with other communities and receive the highest cumulative risk. Its initial risk accounts for 62.50 %, and transmitted risks from other components shares 37.50 %. The integral ecological risk under stringent environmental constraint is 3.49 times higher than that under lenient environmental constraint. The calculated and simulated comprehensive ecological risks indicate a core-periphery distribution pattern, with higher risk concentrated at the center and lower risk towards the edges. Uncertainty in material-energy flows has an insignificant impact on the transmission pathways of ecological risk. However, when the scenario changes from the stringent environmental constraint to the 90 % quantile (from Monte Carlo simulation), the risks of soil microorganisms and carnivores increase by 2.66 % and 21 %, respectively. These findings can offer a scientific basis for identifying contamination sources, analyzing risk transmission processes, and formulating risk management strategies in contaminated sites.