An Approach of Pmf Model Coupled with Stable Isotope Technology to Track Heavy Metals Accumulated in Farmland Soil

Abstract

Source apportionment and precise control of heavy metals in farmland soils are helpful to realize the safe use of agricultural soils and ensure the quality and safety of agricultural products. This study analyzed the concentration and distribution of heavy metals in farmland soils from a typical plain river network area, by collecting cultivated layer, subsoil layer and substratum soil samples. Irrigation water, atmospheric deposition and fertilizers were also collected to explore the input of heavy metals from potential sources. The concentrations of Hg exceeded the standard value, with an exceeding rate of 12.5%. Positive matrix factorization (PMF) and stable isotope technology were used to identify the sources of heavy metals in farmland soils, indicating that heavy metals in farmland soils originated from industrial production (32.0%), natural source (28.2%), agricultural activity (25.8%) and vehicle emission (14.0%). Agricultural activity contributed the most to Hg (51.6%), followed by natural source (20.9%), industrial production (15.4%) and vehicle emission (12.1%). Approximately 79.1% of Hg was affected by external inputs, with agricultural activity contributing 65.2%. These results indicated that the combination of PMF and stable isotope technology is a reliable and promising tool for source apportionment of heavy metals in farmland soils.

Keywords: heavy metals, Farmland soil, source apportionment, receptor model, stable isotope