Li H.; Wu J.; Huang Q.; Lin L.; Yuan B.; Wang Q.; Lu H.; Liu J.; Hong H. and Yan C. 2023. Science of the Total Environment 904.

Coastal sediments act as sinks of sediment organic matter (SOM) and metals because of their special land–sea location and depositional properties. However, there are few reports on the correlation between the sources of organic matter (OM) and associated potential toxic metals (PTMs). In this study, we combined C-N stable isotope analysis and positive matrix factorization to identify the matter and metal sources of OM and glomalin-related soil protein (GRSP) in an estuary under several decades of urbanization. The results of the positive matrix factorization (PMF) reveal a correlation between the sources of total sediment metals and the sources of OM-related metals. The sources of both SOM-bound PTMs and GRSP-bound PTMs are significantly related to the sources of total PTMs. OM sources were elucidated through ¹³C–¹⁵N stable isotopes, and the potential sources of different types of OM differed. In addition, there is a significant correlation between OM-associated PTMs and organic matter sources. Interestingly, the functional groups of SOM were mainly influenced by multiple PTM sources but no OM source, while the functional groups of GRSP were regulated by a single metal source and OM source. This study deepened the understanding of the coupling between PTMs and SOM. The possibility of combined use of positive matrix factorization and ¹³C–¹⁵N stable isotope tracing of metals as well as the sources of each metal fractions has been evaluated, which will provide new insights for the transportation of PTMs.

The metal species with the largest proportion in the sediment is the residual fraction. However, there are also metals max-loading by OM fixed fraction, such as Cd and Mn; or max-loading by sulfide fixed fraction, such as Cu and Pb.