Effects of land reclamation on distribution of soil properties and heavy metal concentrations, and the associated environmental pollution assessment

Abstract

We used the “space for time substitution” method to test the effects of reclamation history on evolution processes of soil properties and heavy metal concentrations. A total of 129 surface soil samples were collected in a reclamation zone of the Liaohe River Delta, which was divided into three reclaimed zones (1930s, 1960s, and 1990s), marsh, and intertidal flats. Soil metals (Fe, Mn, Cd, Cr, Cu, Ni, Pb, and Zn), soil particle size, pH, salinity, soil organic carbon (SOC), nitrate nitrogen (NO3--N), and available phosphorus (AP) were analyzed. Results obtained from correlation analysis and factor analysis showed that there were significant positive correlations (p<0.01) between the fine particle fractions (clay and silt) and metal concentrations. Using ANOVA, we found that soil erosion and leaching desalination had significant effects on the distributions of soil properties and heavy metal contents in short-term reclamation (1990s zone), and that sustained human activities have played an important role in long-term reclamation (1960s zone). Results of the enrichment factor (EF) and inverse distance weighting (IDW) indicated that Cd pollution had reached high pollution levels, followed by Cr pollution. Taking necessary measures is significant for sustainable utilization and management of coastal resources.