Abstract:
The Luxikou goose-head braided channel in middle reaches of the Changjiang River is situated in national nature reserve.In order to identify the spatial distribution and sources of heavy metals in the soil, and to serve the regional ecological environment and species protection, 43 soil samples were collected to analyze the contents and spatial distribution characteristics of heavy metals (As, Cd, Cr, Cu, Hg, Ni, Pb, Zn), including topsoil (0~20 cm) and subsoil (50~200 cm) in Luxikou braided channel before and after flooding.Heavy metal risk was evaluated and the sources were analyzed by principal component analysis and PMF model.The results showed that: ① the ratio of heavy metal elements in surface soil to the background value of Hubei Province followed the order Cd > Cu > Pb > Zn > Hg > Ni > Cr > As, and the concentrations in topsoil were higher than those in subsoils.② On spatial distribution, the soil heavy metal elements in the zone were concentrated in the middle of the head of Zhongzhou and the tail of Xinzhou.The metals were deposited on the surface, and migrated towards the center of the zone.After flooding, heavy metal concentrations near the river channel decreased, while it increased near the center of the zone.③ According to geo-accumulation index and potential ecological risk index, Cd was classified as moderately polluted (The average of
Igeo was 1.26) and at strong potential ecological risk (The average of
Eri was 116.32), Hg was at moderate risk (The average of
Eri was 52.77), while the remaining elements were mostly unpolluted and posed a low potential risk.④ Based on principal component and PMF source analysis, Pb originated from both natural geological background and river transportation with roughly equal contribution, while Hg primarily came from shipping fuel combustion emissions.The others mainly originated from natural geological backgrounds.The soil heavy metals in Luxikou goose-head braided channel mainly come from the natural geological background and waterway transportation, and their contributions accounted for 74.56% and 25.44%, respectively.Supervision of the use and management of fuel oil by vessels in the waterway can be strengthened to further protect regional species and the ecological security of the Changjiang River.