This study aimed to understand the seasonal and spatial variations of N₂O emissions from newly created littoral marshes in the drawdown area of the Three Gorges Reservoir (TGR), China. We measured N₂O emissions at 10-day intervals during the growing season (early July to late September) in 2008. N₂O emissions were measured with static chambers in four typical vegetation stands. The results showed great spatial variations of N₂O emissions among the four stands. The greatest N₂O emissions (0.052 ± 0.063 mg N₂O m⁻² h⁻¹) were from Scirpus triqueter stand, while the lowest N₂O emissions (0.020 ± 0.020 mg N₂O m⁻² h⁻¹) were from Typha angustifolia stand. To such spatial variations in N₂O emissions, standing water depths and soil water content may be important explaining factors. Besides spatial variations, we also found significant temporal variations of N₂O emissions in this area. The temporal variation of N₂O emissions in the growing season was not found significantly related to any measured factor in the study. However, based on principal component analysis, we consider it partly caused by thermal conditions and the marked temporal variation of the standing water depth in the growing season, which to some degree influenced the process of denitrification and N₂O emissions. These results about TGR enable us to make a more reasonable estimate of N₂O emissions from large dam reservoirs, particularly those with a large drawdown area in the growing season in an agricultural landscape.

The contamination status of rivers and their floodplains with inorganic and organic pollutants in central Russia is poorly known. We investigated the concentrations of inorganic (As, Cd, Cu, Hg, Ni, Pb and Zn) and persistent organic pollutants (hexachlorocyclohexane, PCBs, cyclodienes, DDX and other pesticides) in floodplain soils of the Oka River catchment (Russia). The level of contamination was generally lower than in the Elbe River floodplain but in the same range as in other European river systems such as floodplains of the rivers Rhine, Dřevnice and Yachroma. Only soil samples from the periphery of the city of Ryazan (200 km southeast of Moscow) had a higher anthropogenic enrichment of Cd, Cu and Zn which was comparable to the contaminated Elbe River floodplains. These soils also had the largest concentrations of persistent organic pollutants among all samples from the Oka River catchment. Therefore, the need for large-scale remediation seems to be less urgent than in Central European river catchments and mainly restricted to some “hot spot” areas.

Paleolimnological techniques were utilized to determine whether diatom and scaled chrysophyte assemblages in Daisy, Swan, and Tilton lakes (Sudbury, Ontario) have recovered toward their preimpact conditions as a result of reduced inputs of anthropogenic pollutants (SO ₄ ²⁻ and metals) or whether other environmental stressors have affected recovery trajectories. In addition, geochemical analysis was used to track trends in sedimentary nickel and copper concentrations through time. Preindustrial algal assemblages were primarily dominated by circumneutral to alkaline and pH-indifferent taxa. However, with the onset of open-pit roasting and smelting operations, there was a stratigraphic shift toward acid-tolerant species. With wide-scale smelter emission reductions commencing in the 1970s, scaled chrysophyte assemblages in Swan and Daisy lakes have started to show signs of biological recovery in ∼1984 and ∼1991, respectively. Although the scaled chrysophyte assemblage in Tilton Lake has not recovered toward the predisturbance assemblage, the decline in acidophilic taxa and increase in circumneutral taxa in recently deposited lake sediments indicate that the community is responding to increased lake water pH. Conversely, diatom assemblages within each of the study lakes have not begun to recover, despite well-documented chemical recovery. It is suspected that biological recovery in Sudbury area lakes may be impeded by other environmental stressors such as climate warming. Copper and nickel concentrations in lake sediments increased with the onset of mining activities and subsequently declined with emission controls. However, metal concentrations in lake sediments remain elevated compared to preindustrial concentrations. Together, biological and geochemical evidence demonstrates the clear environmental benefits associated with smelter emission controls.

The present study determines the source of dust particles and investigates their impact on the chemical compositions of plants and soils around a cement factory in Oman within a radius of 10 km of this disturbed ecosystem. A total number of nine samples of the species of plants (Rhazya stricta), nine samples of soils, and nine samples of dust were collected and analyzed for major ions and trace elements including rare earth elements (REEs). Principal component analysis applied to the major and trace element concentrations in the dust indicated the input of at least two sources to the dust in the study area: ophiolites and cement. The REE distribution in the plants and soils revealed that the most available elements to plants originated dominantly from ophiolites rather than from cement. The contribution of cement industry is significant only in the zone located at about 0.500 to 2 km around the cement factory, whereas the contribution of ophiolites increases with distance from the cement factory.

The city of La Plata and its surroundings are a very populated area, which has an important Industrial Pole and intense traffic activity but environmental studies have been rare so far. This article presents and discusses the importance of wind frequencies and velocities for the transport of air pollutants. The study emphasizes the importance of knowing wind patterns on an hourly basis that can be helpful for designing a monitoring network as well as for preventing exposure to pollutants. Correlation between monthly SO₂ concentrations and wind frequencies and velocities are discussed for a particular set of directions NNW-NE that carry pollutants from industrial sources toward populated areas. As a result, averaged wind frequencies have been found to be very important for determining patterns influencing pollutants transport; the influence of averaged velocities has shown low variability (hourly and monthly). Hierarchical cluster analysis applied to wind roses provided a useful approach for analyzing and describing the general daily occurrence of winds.

This study was carried out in order to assess both the deposition of heavy metal and nitrogen in a mountain ecosystem with low levels of metal deposition and its possible interactions with factors such as lithology and topography. For this purpose, samples of Hypnum cupressiforme Hedw. and topsoils were collected in a forest catchment within Bertiz Natural Park, an International Cooperative Programme on Integrated Monitoring site. Trace metals levels in mosses can be considered low compared with values reported elsewhere in Europe, and the dust soil mineral particles seemed to be the main source of these values. Only Cd and Hg presented external inputs, probably with an anthropic origin, for mosses according to the enrichment factor values, whereas historical pollution-related deposition in soils was determined for Pb, Cu, and Ni, attending to their total/extractable ratio.

Biodegradation kinetics of 3-chlorophenol (3-CP) were studied in two identical lab scale sequencing batch reactors (SBR) fed with the compound as the sole energy and carbon source and operated at different filling time (1 h for SBR1 and 2 h for SBR2). High removal efficiency was always obtained in both SBRs in the range of feed concentration of 300-960 mg L⁻¹. Increased feed load to 1,200 mg L⁻¹ 3-CP could also be removed in SBR1 despite the presence of inhibition, whereas determined failure of SBR2. Long filling time and high biomass concentration were shown to have beneficial effect on process kinetics since they allowed to avoid substrate concentration peaks at the end of the fill phase. However, longer filling time (in the present case higher than 1 h) did not allow to select and enrich robust microbial population. The Haldane equation well fitted the kinetic test data measured in the presence of inhibition, i.e., at 960 and 1,200 mg L⁻¹ 3-CP in SBR1.

The main objective of this study was to examine the efficacy and capacity of constructed wetlands for metal removal. Between January 2006 and December 2008, removal of Cr, Cu, Cd, Zn, Pb, B, Ni, As, Fe, Hg, and Mn was measured on a monthly basis at a hierarchical mosaic of artificial ecosystems which has been in operation since 1998. The results showed a great variety of average removal efficiencies, in the range of 55% for chromium and −73% for manganese. Four elements presented negative removal: nickel, iron, arsenic, and manganese. Seasonal removal efficiencies were also studied for each element. Moreover, a correlation assessment among metal removal efficiencies and different parameters of each basin in the hierarchical mosaic of artificial ecosystems was performed. Negative significant correlations were found among Fe, Zn, Cu, Mn, As, Ni, Cd, and Hg removal and the inlet concentrations. In general, the treatment system was not a good system for removal of metals from wastewater as, in relation to other constructed wetlands, the system was not able to provide efficient removal of metals.

An exploratory survey of the mercury content of some common California biomass feedstocks shows that the concentrations are well below EPA toxicity levels with representative feedstock concentrations of 20 ppb for rice straw, 28 ppb for wheat straw, and 32 ppb for whole-tree wood chips. The temporal variability for rice straw (17-20 ppb) is near the analytical uncertainty (∼2 ppb). Saline-irrigated feedstock does not contain greatly higher mercury contents (17-38 ppb) compared to normally irrigated feedstock. Water leaching has likewise no detectable effects on mercury mobility, despite an up to 30% increase in the Hg concentrations attributable to mass losses during leaching. Combustion at temperatures of at least 575°C results in complete volatilization of mercury leaving solid ash and slag residuals with mercury contents at or near the lower limit of detection (5 ppb). The mercury strongly concentrated in fly ash can reach concentrations up to 40 times (<1,166 ppb) the corresponding fuel concentrations.

Cultures of the flagellate Isochrysis galbana were used to carry out the ecotoxicological evaluation of four PAHs [(naphthalene, phenanthrene, pyrene (Pyr) and fluoranthene (Flu)] by monitoring growth rate and the fluorescence variables F ₀, F m, F v and F v/F m, determined with a fast repetition rate fluorometer. The results presented in this investigation showed that F v was a suitable endpoint in acute ecotoxicological tests with marine phytoplankton. The derived effective concentrations followed the known narcotic mechanism of toxicity and showed sensitivity levels comparable to marine invertebrate embryo-larval bioassays. Pyr and Flu showed the lowest EC₁₀, which ranged between 168-279 and 189-697 nM, respectively.