Divergent Temporal Changes of Heavy Metals in the Soil Induced by Natural Versus Anthropogenic Forces: A Case Study in the Yangtze River Delta Area, China

Abstract

The contributions of natural versus anthropogenic forces on temporal changes of metals in the soil of the Yangtze River delta region were successfully quantified by combining repeated soil sampling, geostatistics and the modified principal component scores and multiple linear regressions approach. The findings show that soil Hg concentration significantly decreased from 2010 to 2020, and the decrease of Hg content was predominately driven by the geochemical processes, with 48% contribution. The Pb concentration increased by 40%. About 76% of the Pb change was attributed to the strengthened development of Pb battery industry in the south of the Yangtze River delta. The battery industry development also contributed 48% of the change of Cd. The anthropogenic activities involving Cu, Zn or fossil fuel consumption contributed 32-35% of the changes of As, Cu and Zn concentrations in the soil. Steel industries contributed 82% of Cr and 60% and Ni changes, respectively. Though Cu, As, Ni and Cr in the soil exhibited no significant difference between 2010 and 2020, the low proportion of sites with As, Cu, Ni or Cr increased and their spatial pointwise distributions, makes it expected to observe a significant decline in the concentrations of these elements in the coming decades.

Keywords: accumulation, source appointment, repeated sampling, temporal-spatial, Pollution