Batch experiments were conducted to test the effects of various solution properties, such as pH, temperature, initial concentration and anoxic and aerobic atmosphere, on Cd removal by nanoscale zerovalent iron (nZVI) supported on industrial coal fly ash. Cd (II) could be removed by adsorption on fly ash-nZVI in a very short time (5 min) with high removal rates (greater than 99.9%) over a wide range of concentration (5–100 mg l−1). Cd (II) was physically adsorbed on the surface of fly ash-nZVI. The preparation of fly ash-nZVI can incorporate the use of waste media, making the overall adsorbent more removal efficient and low cost.

This study aimed to determine sediment contamination in the Beidagang Wetland Nature Reserve to describe atmospheric deposition of trace metals. We analyzed Hg, Cd, Pb, TOC, TN, TP, δ13C, and δ15N, and studied their variations in surface sediments and in the vertical profiles of sediment cores collected from the reserve. Evaluation of environmental trace metal contamination using sediment quality guidelines and geochemical background values indicated that the risk of metal pollution in the reserve sediments was relatively low. Concentrations of Hg, Cd, and Pb in the sediments were much lower than concentrations in sediment samples from Bohai Bay and polluted rivers in Tianjin. Enrichment factors indicate that samples are moderately contaminated with Hg, Cd, and Pb; whereas the geo-accumulation index results classify the sediments as uncontaminated to moderately contaminated with Hg, Cd, and Pb. The distribution patterns of trace metal concentrations in the three core samples were uniform. δ13C and δ15N were used to track the sources of TOC and TN in sediments. Results show that TOC mainly originated from the residue and decaying matter of aquatic plants (e.g., algae, reeds, and Typha), while TN was derived from soil N and elevated atmospheric N deposition. Because domestic and industrial waste is not discharged into the Beidagang Wetland Nature Reserve, trace metals found in sediments mainly originate from atmospheric deposition. The results provide baseline data for analysis of trace metal accumulation in Beijing-Tianjin-Hebei, a region subject to atmospheric deposition in northern China.

No abstract

Concentrations, distributions, and potential sources of DDTs and HCHs in seawater, sediments, soils, and atmosphere were collected to review their pollution statuses in the Bohai Sea and its coastal areas. In comparison to various sediment and seawater quality standards, DDTs and HCHs in sediments and seawater were at low levels in the entire Bohai Sea and might not cause adverse biological effects. However, DDTs and HCHs levels in various sea areas were closely associated with local pesticides production and application as well as hydrodynamic. DDTs and HCHs showed an obvious spatial distribution pattern. High levels were found in the Bohai Bay, Haihe River and Yellow River estuary. DDTs and HCHs concentrations in river and estuary sediments were higher than sea sediments and a seaward decreasing trend was observed. Although HCHs and DDTs residues in the Bohai Sea primarily originated from river runoffs (pesticide factory wastewater, historical applications and residues of technical HCH and DDT, etc.), additional sources of lindane and dicofol existed. Runoff from the demolished old pesticide factories might be another source. Further researches are highly recommended on pollution hotpots of DDTs and HCHs and investigate their migration and transformation at sediment-water interface and pollution history from sediment depth profiles.