Distribution of heavy metals and the exploration of potential indicators and hyperaccumulators in Jiang'an River, Chengdu, PR China

As a highly toxic contaminant, heavy metals have been proven to be widely distributed in the water and sediments of the global oceans, rivers, and lakes. Due to the functional differences in urban areas, the extent, characteristics, and hazards of heavy metal pollution in rivers are also different. To monitor and eliminate heavy metal pollution in rivers, indicators and hyperaccumulators perform crucial roles. In this study, heavy metal concentrations in the water, sediment, benthic faunae and aquatic plants of the Jiang'an River (which flows through Chengdu city, Sichuan Province, P.R. China) were investigated, followed by heavy metal correlation analysis of different media to identify potential bioindicator and hyperaccumulator. The results demonstrated that, none of the heavy metals were detected in the water. However, the 6 heavy metals in the surface sediments showed dramatic spatial regional differences, with Ni-As, Ni-Pb, Ni-Cr, Cr-Cu and Cr-Zn being highly significantly correlated. Furthermore, heavy metal contents in surface sediments were highly significantly correlated with the enrichment capacity of Eriocheir sinensis, Polypogon fugax, and Setaria viridis, and significantly correlated with Erigeron acer. Moreover, all plants were poorly enriched with Pb, which may be related to the morphology of Pb in the sediments. Besides, Eriocheir sinensis is a potential indicator of Zn and Cr in the sediments, and Erigeron acer is a possible Zn hyperaccumulator. This research confirms that heavy metals migrated in the water–sediment-benthic-plant system. Therefore, this study can provide a theoretical foundation for river monitoring and administration in Chengdu city and Sichuan Province.