[Distribution and Pollution Assessment of Nutrients and Heavy Metals in Surface Sediments from Shibalianwei Wetland in Hefei, Anhui Province, China].

Shibalianwei is a large constructed wetland formed at the estuary of the Nanfei River adjoining Lake Chaohu. To investigate the distribution and pollution characteristics of nutrients and heavy metals in surface sediments of Shibalianwei Wetland, sediment samples were collected from 72 sites in July 2018. The source of the pollution was analyzed. Our results showed that the average contents of total nitrogen (TN), total phosphorus (TP), and organic matter (OM) in surface sediments of Shibalianwei were 2108.87 mg·kg-1, 1448.82 mg·kg-1, and 86.2 g·kg-1, respectively; in the external water system of the wetland, they were 2305.81 mg·kg-1, 1268.46 mg·kg-1, and 59.9 g·kg-1, respectively. The average contents of heavy metals of Mn, Cr, Cu, Pb, Cd, As, and Hg in Shibalianwei were 462.58, 42.12, 21.69, 18.05, 0.63, 5.67, and 0.059 mg·kg-1, respectively; in the external water bodies, they were 381.61, 36.85, 24.74, 30.70, 2.49, 6.47, and 0.035 mg·kg-1, respectively. In the assessments of nutrient pollution of internal water bodies of Shibalianwei, TN was at mild to moderate pollution levels, TP was at a heavy pollution level, and the comprehensive pollution index (FF) indicated that nutrients in Shibalianwei were at moderate to heavy pollution levels. The assessment results of the organic pollution index (OI) were consistent with the FF. The potential ecological risk assessments of heavy metals showed that both Cd and Hg reached certain ecological risks, which were indicated by RI and Eri. For external water bodies, the nutrient levels were also high and heavy metal pollution was relatively serious, indicating high ecological risks.

[Effects of gravel mulch technology on soil erosion resistance and plant growth of river flinty slope].

Aiming at the technical difficulties such as the stability and water balance in the ecological rehabilitation of river flinty slope, a gravel mulch technology was proposed, with the effects of different gravel mulch treatments on the soil anti-erosion capacity, soil water retention property, and plant growth investigated by anti-erosion and pot experiments. The results showed that mulching with the gravels 1.5-2 cm in size could obviously enhance the soil anti-erosion capacity, soil water retention property and plant biomass, but no obvious differences were observed between the mulch thickness of 5 cm and 8 cm. It was indicated that mulching with the gravels 1.5-2 cm in size and 5 cm in thickness was an effective and economical technology for the ecological rehabilitation of river flinty slope.