Concentrations, diffusive fluxes and toxicity of heavy metals in pore water of the Fuyang River, Haihe Basin

• Metals in pore water provide important information about their bioavailability.
• Contamination levels of metals were observed in pore water of the Fuyang River.
• Cr, Ni, Cu and As had positive diffusive fluxes from pore water to overlying water.
• There was a potential risk of toxicity from Cu to the aquatic organisms.

While the concentrations of heavy metals in pore water provide important information about their bioavailability, to date few studies have focused on this topic. In this study, pore water in river sediments collected from nine sampling sites (S1–S9) was examined to determine the concentrations, fluxes, and toxicity of heavy metals in the Fuyang River. The results showed that the average concentrations of Cr, Ni, Cu, As, Zn, and Pb in pore water were 17.06, 15.97, 20.93, 19.08, 43.72, and 0.56 μg L−1, respectively; these concentrations varied as the pore water depth increased. The diffusive fluxes of Cr, Ni, Cu, As, Zn, and Pb were in the following range: (−0.37) to 3.17, (−1.37) to 2.63, (−4.61) to 3.44, 0.17–6.02, (−180.26) to 7.51, and (−0.92) to (−0.29) μg (m2 day)−1, respectively. There was a potential risk of toxicity from Cu to aquatic organisms, as indicated by a value of the Interstitial Water Criteria Toxic Units that exceeded 1.0. Values of the Nemeraw Index were 2.06, 0.48, 0.11, 0.20, 1.11, 1.03, 0.99, 0.88, and 0.89 from S1 to S9, respectively. Only S1 was moderately polluted by heavy metals in pore water.