Source Appointment of Heavy Metals in Agricultural Soils of the Jiulong River Basin Based on Positive Matrix Factorization

Abstract

In order to study the source appointment of heavy metals in agricultural soils of the Jiulong River Basin, Fujian Province, China. 71 agricultural soil samples were collected in July 2017. The concentrations of heavy metals in agricultural soils were determined by inductively coupled plasma mass spectrometry (ICP-MS) and atomic fluorescence spectrometry (AFS). Here, we use a positive matrix factorization (PMF) model for the source appointment of heavy metals in the sampled soils. The results showed that most of the heavy metal concentrations in the sampled agricultural soils were higher than soil background concentrations for the Fujian Province. The concentrations of Cd, Zn, Pb, and Cu in some soil samples were greater than the screening value of the Chinese soil pollution risk levels for agricultural land (GB 15618-2018). The spatial distributions of heavy metals showed a moderate variation across three regions of the study area (i.e., the North River watershed, West River watershed, and the estuary area). The highest concentration of Cr, Ni, Cu, Zn, and Cd were found in Longyan City (North River watershed), the highest concentrations of Pb were found in the West River watershed, and the highest concentrations of Co, Hg, and As were found in the estuary area. The non-negative properties of the source component spectrum and source contribution rate (obtained by the PMF model), as well as the significant correlation between the measured and PMF predicted concentrations, indicated that the results of the PMF model were relatively reasonable and can meet research needs. The source apportionment results of the PMF model showed that natural sources, agricultural sources, coal combustion, and industrial sources were the four major potential sources for heavy metals in the sampled agricultural soils, contributing 37.0%, 26.7%, 17.6%, and 18.7%, respectively.