Sediment samples were collected to a depth of 60 cm along a 350-m sampling belt in a short-term-flooding riparian wetland in the Yellow River Delta of China in three sampling seasons. Contents of heavy metals were determined to investigate their spatial and temporal distributions, sources and ecotoxities. Our results showed that As contents in the top 20 cm sediments increased before decreasing along the sampling belt in summer, whereas they kept stable before increasing in fall and spring. Cd contents increased along the sampling belt in three sampling seasons, whereas Ni and Cr generally exhibited a decreasing tendency. Comparatively, Cu, Pb and Zn consistently increased at the first 50 m distance and then decreased before increasing from the distance of 150 m in summer and fall and increased to the maximum at the distance of 250 m and then showed a decrease in spring. Two “hotspots” of heavy metal accumulation in sediment cores along the belt were observed at the distance from 50 to 100 m in summer and at the distance from 200 to 300 m in spring. Most of sediment samples contained higher heavy metals in excess of threshold effect levels except for Zn and Pb in three sampling seasons and the values of toxic units in more than 30% of sediment samples exceeded 4 in summer. As, Ni and Cr had relatively higher contribution to the values of toxic units compared with other heavy metals in three sampling seasons. Multivariance analysis showed that As and Cd might originate from the same source and Cu, Zn, Cr, Pb and Ni might derive from another similar source. Cd was significantly correlated with salinity (p < 0.01) and pH (p < 0.05). Meanwhile, these heavy metals were also significantly correlated with other properties such as S, Al, TP, SOM and Silt + Clay.

This study was carried out to evaluate the present-day chemical properties of methylmercury in surface sediment in Minamata Bay where a dredging project was completed 28years ago. Present-day sediment from Minamata Bay consists of sandy silt, and the average loss-on-ignition in surface sediment was 7.0±2.3%. The average methylmercury concentrations in the upper sediment layers were significantly higher than those in the lower sediment layers. Currently, the concentrations in sediments in Minamata Bay do not exceed the Japanese regulatory standard value for mercury. The average concentration of methylmercury in Minamata Bay surface sediment was 1.74±1.0ng/g on a dry weight basis (n=107). The methylmercury concentration in Minamata Bay surface sediment was almost 16 times higher than that in surface sediment from Isahaya Bay surface sediment, which was 0.11±0.045ng/g on a dry weight basis (n=5).

Hurricane Sandy made landfall in Barnegat Bay, October, 29, 2012, damaging shorelines and infrastructure. Estuarine sediment chemistry and toxicity were investigated before and after to evaluate potential environmental health impacts and to establish post-event baseline sediment-quality conditions. Trace element concentrations increased throughout Barnegat Bay up to two orders of magnitude, especially north of Barnegat Inlet, consistent with northward redistribution of silt. Loss of organic compounds, clay, and organic carbon is consistent with sediment winnowing and transport through the inlets and sediment transport modeling results. The number of sites exceeding sediment quality guidance levels for trace elements tripled post-Sandy. Sediment toxicity post-Sandy was mostly unaffected relative to pre-Sandy conditions, but at the site with the greatest relative increase for trace elements, survival rate of the test amphipod decreased (indicating degradation). This study would not have been possible without comprehensive baseline data enabling the evaluation of storm-derived changes in sediment quality.

Sediment samples from the ballast water tanks of ships calling at the port of Rijeka in the Northern Adriatic were analysed using X-ray photoelectron spectroscopy (XPS) and secondary ion mass spectroscopy (SIMS) using caesium, argon and oxygen ion beams. The research was carried out in order to determine the sediment composition and relative abundance of the dominant elements. The results indicate that the sediment samples mostly consisted of compounds that originated from the deterioration of tank plates, tank coating residues and ballast operations such as clay, silt, sand and organic materials. No significant heavy metals or highly toxic elements were found. The research revealed some advantages and significant drawbacks of using XPS and SIMS for the routine analysis of sediment composition as a decision supporting tool for ballast water and sediment management.

This study evaluates the present day effects of air pollutants emitted from an iron sintering plant near Wawa (Ontario, Canada) decades ago (1939–1998). During smelting and refining of iron ore, gaseous sulfur-rich emissions and large amounts of metal-containing (iron oxides) particulate materials were released in to the air, and eventually settled onto vegetation and soil cover. We test the feasibility of using magnetic measurements to investigate and quantify the soil pollution resulting from the sintering plant. Surface and subsurface magnetic susceptibility measurements, as well as various magnetic mineral properties, have been collected in a scheme designed to mimic the previously determined pollutant contamination zones. A total of 50 sites were sampled (with a sampling grid of 250 m) within and around the smelter kill zone to the northwest of Wawa. Results were plotted on cross sections perpendicular (X-X′) and parallel (Y-Y′) to the dominant wind direction in order to investigate magnetic properties of the soil samples as a function of both wind direction and distance from the source. Samples located in Rao and LeBlanc’s (The Bryologist 70:141–17, 1967) pollution zones 1 and 2 typically have κ ᵢₙ₋ₛᵢₜᵤ values >120 × 10⁻⁵ SI, while the zone 3 and 4 results are <100 × 10⁻⁵ SI. Magnetic susceptibility enhancements at depths of 5–10 cm were found to be related to the presence of magnetic spherules (fly-ashes) at sites on the wind-parallel Y-Y′ profile in the previously defined kill zone. An estimated minimum migration rate of iron-rich particulates is calculated for coarse sand and silt/clay sites as 0.24 and 0.1 cm/year, respectively.

This paper comes out from the need to provide an improvement in the current oil refinery wastewater treatment plant (WWTP) aiming to generate water for reuse. The wastewater was pretreated and collected in the WWTP after the biological treatment unit (bio-disks) followed by sand filtration. Ozonation (ozone concentration from 3.0–60 mgO₃ L⁻¹), UV (power lamp from 15 to 95 W), H₂O₂ (carbon:H₂O₂ molar ratio of 1:1, 1:2, and 1:4), and two advanced oxidation processes (UV/O₃ and UV/H₂O₂) were investigated aiming to reduce the wastewater organic matter and generate water with suitable characteristics for the reverse osmosis operation and subsequent industrial reuse. Even after the biological and filtration treatments, the oil refinery wastewater still presented an appreciable amount of recalcitrant organic matter (TOC of 12–19 mgC L⁻¹) and silt density index (SDI) higher than 4, which is considered high for subsequent reverse osmosis due to membrane fouling risks. Experiments using non combined processes (O₃, H₂O₂, and UV only) showed a low degree of mineralization after 60 min of reaction, although the pretreatment with ozone had promoted the oxidation of aromatic compounds originally found in the real matrix, which suggests the formation of recalcitrant compounds. When the combined processes were applied, a considerable increase in the TOC removal was observed (max of 95 % for UV/O₃ process, 55 W, 60 mgO₃ L⁻¹), likely due the presence of higher amounts of reactive species, specially hydroxyl radicals, confirming the important role of these species on the photochemical degradation of the wastewater compounds. A zero-order kinetic model was fitted to the experimental data and the rate constant values (k, mgC L⁻¹ h⁻¹) ranged from 4.8 < k UV/O₃ < 11 ([O₃]₀ = 30–60 mg L⁻¹), and 8.6 < k UV/H₂O₂ < 11 (C:H₂O₂ from 1:1 to 1:4). The minimum and maximum electrical energy per order (E EO) required for 60 min of treatment were calculated as 5.4 and 81 Wh L⁻¹, respectively, for UV/O₃ (15 W, 60 mgO₃ L⁻¹) and UV/H₂O₂ (95 W, 1C:1H₂O₂). Good results in terms of water conditioning for reverse osmosis operation were obtained using UV/H₂O₂ process with initial molar ratio of 1 C:2 H₂O₂ (UV lamp 55 W) and 1 C:4 H₂O₂ (UV lamp 95 W), and total organic carbon (TOC) removals of 62 % (SDI₁₅ = 1.8) and 74 % (SDI₁₅ = 2.0) were achieved, respectively, after 60 min. The treated wastewater followed to the reverse osmosis system, which operated with an adequate flux of permeate, was very efficient to remove salt and generate a permeate water with the required quality for industrial reuse.