Quantifying the decoupling of pollution magnitude and geochemical signatures in livestock manure: a novel geometric fingerprint approach
摘要
The rapid transition from backyard to industrial livestock production has profoundly altered the geochemical characteristics of agricultural wastes, yet conventional risk assessment frameworks remain predominantly concentration-oriented and lack the capacity to resolve structural imbalances within the heavy metal suite. This study proposes a novel two-dimensional geometric fingerprinting framework to quantify the decoupling between pollution magnitude and structural distortion in livestock manure. A total of 204 manure samples were collected from a representative intensive farming region in the Sichuan Basin, Southwest China. Eight heavy metals and pH were analyzed, and concentrations were dynamically normalized using the pH-dependent thresholds defined in the Ministry of Ecology and Environment of the People’s Republic of China standard GB 15618-2018. Two geometric descriptors were derived from radar projections of risk quotients: the comprehensive risk area (Sarea), representing cumulative pollution magnitude, and the coefficient of variation (CV), quantifying fingerprint distortion. Results revealed a significant expansion of pollution magnitude under industrial farming, accompanied by intensified structural imbalance, primarily driven by excessive Cu and Zn inputs. Principal component analysis further confirmed a clear structural divergence between backyard and industrial systems. Critically, no significant linear correlation was observed between Sarea and CV, demonstrating a stochastic decoupling between total load and geochemical structure. This dual-indicator framework reveals that pollution magnitude does not inherently predict structural distortion, highlighting the inadequacy of single-metric assessments. By integrating dynamic regulatory normalization with geometric topology, the study establishes a structural early warning paradigm for manure management.