Are breaking waves,bores, surges and jumps the same flow?

The flow structure in the aerated region of the roller generated by breaking waves remains a great challenge to study, with large quantities of entrained air and turbulence interactions making it very difficult to investigate in details. A number of analogies were proposed between breaking waves in deep or shallow water, tidal bores and hydraulic jumps. Many numerical models used to simulate waves in the surf zone do not implicitly simulate the breaking process of the waves, but are required to parameterise the wave-breaking effects, thus relying on experimental data. Analogies are also assumed to quantify the roller dynamics and the energy dissipation. The scope of this paper is to review the different analogies proposed in the literature and to discuss current practices. A thorough survey is offered and a discussion is developed an aimed at improving the use of possible breaking proxies. The most recent data are revisited and scrutinised for the use of most advanced numerical models to educe the surf zone hydrodynamics. In particular, the roller dynamics and geometrical characteristics are discussed. An open discussion is proposed to explore the actual practices and propose perspectives based on the most appropriate analogy, namely the tidal bore.     

Large eddy simulation of flow and scalar transport in a vegetated channel

Predicting flow and mass transport in vegetated regions has a broad range of applications in ecology and engineering practice. This paper presents large eddy simulation (LES) of turbulent flow and scalar transport within a fully developed open-channel with submerged vegetation. To properly represent the scalar transport, an additional diffusivity was introduced within the canopy to account for the contribution of stem wakes, which were not resolved by the LES, to turbulent diffusion. The LES produced good agreement with the velocity and concentration fields measured in a flume experiment. The simulation revealed a secondary flow distributed symmetrically about the channel centerline, which differed significantly from the circulation in a bare channel. The secondary circulation accelerated the vertical spread of the plume both within and above the canopy layer. Quadrant analysis was used to identify the form and shape of canopy-scale turbulent structures within and above the vegetation canopy. Within the canopy, sweep events contributed more to momentum transfer than ejection events, whereas the opposite occurred above the canopy. The coherent structures were similar to those observed in terrestrial canopies, but smaller in scale due to the constraint of the water surface.     

Heavy metals in soils from a typical industrial area in Sichuan,China: spatial distribution,source identification,and ecological risk assessment

Anthropogenic activities could result in increasing concentrations of heavy metals in soil and deteriorating in soil environmental quality. Topsoil samples from a typical industrial area, Shiting River Valley, Sichuan, Southwest China, were collected and determined for the concentrations of Cu, Zn, Cr, Cd, As, and Hg. The mean concentrations of these metals were lower than the national threshold values, but were slightly higher than their corresponding background values, indicating enrichment of these metals in soils in the valley, especially for Cu, Zn, and Hg. The topsoils in this area demonstrated moderate pollution and low potential ecological risk. Principal component analysis coupled with cluster analysis was applied to analyze the data and identified possible sources of these heavy metals; the results showed that soil Cd, Hg, As, Cu, and Zn were predominantly controlled by human activities, whereas Cr was mainly from the parent material. The spatial distribution of the heavy metals varied distinctly and was closely correlated to local anthropogenic activities. Furthermore, the concentrations of heavy metals in the industrial land demonstrated relatively higher levels than those of other land use patterns. Soil metal concentrations decreased with the distance increase from the traffic highway (0–1.0 km) and water system (0–2.0 km). Additionally, soil properties, especially pH and soil organic matter, were found to be important factors in the distribution and composition of metals.     

Concentration,sources and risk assessment of PAHs in bottom sediments

Environmental Science and Pollution Research - The aims of the study were to investigate the concentration, sources and ecological risk of PAHs (polycyclic aromatic hydrocarbons) in bottom...     

The Influence of Landscape Patterns on the Bird Diversity of Four Urban Parks

In our study, we aimed to investigate the influence of landscape patterns on the diversity of birds in four urban parks. The parks are located in a region that has a high value of regional biodiversity and is also highly urbanized (Jundiai, state of São Paulo [SP], in Southeastern Brazil). Using a set of aerial photos, the surrounding landscape was divided into two regions (rings) and corresponding landscape metrics were calculated. The presence of bird species was recorded monthly over a one‐year period and classified according to selected ecological criteria. The land cover of the areas surrounding each park was primarily buildings and residences. Bird diversity was significantly correlated with the presence/proximity of water bodies. We state that the potential of the parks to harbor bird species is not negligible. Managing the area surrounding a park to increase the percentage of forested area and the size of forest fragments is as crucial as managing the core park area, especially for improving its attractiveness for new bird species.     

Can pine needles indicate trends in the air pollution levels at remote sites?

Data from ten years of integrated monitoring were used here to evaluate whether pine needles are a feasible tool for an assessment of long-term trends of the atmospheric contamination. Pine needles collected once a year were compared to high volume air samples collected for 24 h, every 7 days, and passive air samples integrated over 28-day periods. Results showed the same concentration patterns of polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) captured in needles and high volume samples. Passive air samplers were less efficient in sampling the particle-bound compounds. Theoretical air volume equivalent to each needle sample (V_EQ) was calculated as a ratio of the needle concentration over the mean air concentration. Results indicated different equivalent volumes for PAHs and organochlorines, possibly due to the faster degradation rates of PAHs in needles. The most important finding is that in the long term a needle monitoring gives very similar information on temporal trends of the atmospheric pollution as does a high volume air monitoring.     

Occurrence and behaviour of selected hydrophobic alkylphenolic compounds in the Danube River

Six hydrophobic alkylphenolic compounds were investigated for the first time simultaneously in four different matrices in the Danube River. Maximum sediment concentrations were 2.83, 2.10, 0.28, and 0.035 mg kg⁻¹ for nonylphenol, nonylphenol monoethoxylate, nonylphenol diethoxylate and octylphenol. Maximum levels in suspended particulate matter (SPM) were 0.18, 0.12, 0.10, and 0.003 mg kg⁻¹. No correlation between concentrations in SPM and sediments was found. Octylphenol monoethoxylate and octylphenol diethoxylate were recorded only in sediment at one location. In mussels and water only nonylphenol and octylphenol were found. Nonylphenol concentrations in mussels (up to 0.34 mg kg⁻¹) correlate with concentrations found in SPM and indicate a slight bioaccumulation. Concentrations in water were close to the limit of quantification. We assume in situ formation of nonylphenol monoethoxylate and nonylphenol in sediments at some locations. In some cases nonylphenol in sediments exceeded the provisional EU environmental quality standards.     

Microbial transformation of synthetic estrogen 17α-ethinylestradiol

Natural estrogens such as estrone, 17β-estradiol, estriol, and the particularly recalcitrant synthetic estrogen 17α-ethinylestradiol used as oral contraceptive, accumulate in the environment and may give rise to health problems. The processes participating in their removal from soil, wastewater, water-sediments, groundwater-aquifer material, and wastewater or sewage treatment plant effluents may involve the action of bacterial and microbial consortia, and in some cases fungi and algae. This review discusses the different efficiencies of bacterial degradation of 17α-ethinylestradiol under aerobic and anaerobic conditions, the role of sulfate-, nitrate-, and iron-reducing conditions in anaerobic degradation, and the role of sorption. The participation of autotrophic ammonia oxidizing bacteria and heterotrophic bacteria in cometabolic degradation of estrogens, the estrogen-degrading action of ligninolytic fungi and their extracellular enzymes (lignin peroxidase, manganese-dependent peroxidase, versatile peroxidase, laccase), and of algae are discussed in detail.     

Investigation of PCDD/Fs and dl-PCBs in fish from the southern Baltic Sea during the 2002–2006 period

Concentrations of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and dioxin-like polychlorinated biphenyls (dl-PCBs) in the southern Baltic herring (Clupea harengus), sprat (Sprattus sprattus), and salmon (Salmo salar) are reported.The significant interspecies and season-specific differences in PCDD/Fs and dl-PCBs concentrations were observed. The contribution of dl-PCBs to the total toxicity equivalents (TEQs) ranged between 50% and 70%, dependently on fish species. In all samples, concentrations of PCDF were higher in comparison with that of PCDD.The permissible limits of the content of PCDD/Fs and dl-PCBs (8 pg g⁻¹ fresh weight for the sum of PCDD/Fs and dl-PCBs, and 4 pg g⁻¹ fresh weight for the PCDD/Fs) were exceeded mainly in salmon samples (in 80% of salmon samples studied). The elevated levels of PCDD/F and dl-PCB were observed only in two of seventy two herring samples, and in ten of 62 sprat samples.The multiple regression analysis revealed that fish lipid content, and concentration of PCB 153, used simultaneously, might be useful in the prediction of TEQ values of fish samples. These two variables explained more than 80% of total variance. For all fish species studied, the correlation coefficients obtained with the multiple regression analysis were higher than that obtained with the regression analysis involving total TEQ values, and only one independent variable: fish lipid content.     

Degradation of hop bitter acids by fungi

Nine fungal strains related to: Trametes versicolor, Nigrospora oryzae, Inonotus radiatus, Crumenulopsis sororia, Coryneum betulinum, Cryptosporiopsis radicicola, Fusarium equiseti, Rhodotorula glutinis and Candida parapsilosis were tested for their ability to degrade humulones and lupulones. The best results were obtained for T. versicolor culture, in which humulones and lupulones were fully degraded after 4days of incubation in the dark or after 36h in the light. The experiments were performed on a commercial hop extract and on sterilized spent hops.