Nitrogen transformation in two subsurface infiltration systems at pilot scale

Nitrogen removal and transformations were studied in two pilot-scale combinations of a special configuration of a subsurface wastewater infiltration system with vertical flow named symbiotic treatment^®. Both pilot-scale combinations operated in parallel and each one consists of four stages in series, one of them with a vertical distribution of stages and the other one with a horizontal distribution. The main differences between them were the separation between stages (presence (the horizontal distribution)/absence (the vertical distribution) of filtration between steps), the hydraulic load (0.113 m³/m² h and 0.082 m³/m² h for the horizontal and the vertical distribution, respectively) and the depth of the soil filters (1 m each stage in the horizontal distribution whereas the depths in the vertical distribution ranges from 20 cm to 40 cm). Results of both configurations showed elevated dissolved oxygen concentration, and high removal of organic matter and total suspended solids (with mean removal values of 96% for COD for both plants and 90% and 98% for TSS for the vertical and the horizontal distribution, respectively). High total Kjeldahl nitrogen removals were obtained in both configurations (mean removals of 70% and 90% for the vertical and the horizontal distribution, respectively). Whereas the nitrification potential was higher in the configuration with horizontal distribution which includes pumping and filtering between stages and higher depth of the soil filters, both tested configurations showed promise for nitrification of wastewater, ammonia nitrogen was efficiently transformed to nitrate.     

城市高架桥的景观优化途径初探

21世纪以来,中国进入快速城市化进程。市政基础设施之一的城市高架桥作为现代城市演进的必然产物,成为城市景观的重要组成部分,但其在解决城市交通问题的同时,也带来一系列诸如环境污染、景观破坏等城市问题。本文将城市高架桥在景观语境下进行剖析,从高架桥自身形态美化、废弃高架桥的景观利用与再生、拆除高架桥后的生态修复3个方面,结合国内外成功的实践案例,提出了城市高架桥的景观优化途径,并倡导在中国推行城市市政基础设施景观化的基本理念。     

Biology outside the classroom: the SNAB visit/issue report

Pitfall trap sampling of Carabid beetle species on roundabouts in Bracknell, Berkshire, was used to assess the biodiversity of this taxon by its use as an indicator. The aim of the study was to discover the role of traffic islands in the provision of refugia for invertebrate fauna in fragmented urban habitats. Sampling was performed on 15 roundabouts where a total of 24 species were recorded during four trapping periods over a total of 10 days. The resulting asymptotic curves indicated that the total number of species present on all but two of the sites had been represented in the samples taken. There was found to be a positive correlation between the area of the islands and the number of ground beetle species and between the log of the area and the number of individuals found. The log/log relationship between the area of the islands and the number of species was significant. The total abundance of the beetles present was also positively and significantly correlated with roundabout area when both variables were logged. The number of habitats on the islands was positively correlated with the total abundance and species richness. The relationship between species, area and habitat was also positively and significantly correlated. In conclusion, it is obvious that roundabouts of large area with higher numbers of habitat types are greater in Carabid beetle diversity than small, sparsely vegetated roundabouts. Thus, roundabouts can promote the maintenance of biodiversity in fragmented urban habitats.We present this study as an example of a simple method that could be used or easily adapted for educational use, and suggest how some of the perceived problems in its use may be overcome. We discuss how such a study could be useful in illustrating concepts such as biodiversity and species richness, and some of the factors that influence it, as well as demonstrating the level of biodiversity that can be found in urban environments.     

Colonizing potential of Drosophilidae (Insecta,Diptera) in environments with different grades of urbanization

Modern environmental destruction through human action has had a big impact on biological diversity. In the Brazilian Cerrado, the second largest South American biome, more than 60% of the native vegetation has been devastated mainly due to anthropic activities. One of the consequences of these activities is the distinct dispersion patterns of endemic and colonizer species in urban environments. In this report we assess the colonizing potential of drosophilids in environments with different grades of urbanization, defined according to the vegetation cover, edifications and demographic density. We performed 12 monthly collections in the city of Brasília, the capital of Brazil, which is located in the core region of the Cerrado. Although we identified 16 species, 90% of the 22,509 captured specimens were Zaprionus indianus, a species recently introduced in Brazil, and the cosmopolitan D. simulans. We captured all the exotic species that occur in the Biome, with the exception of D. kikkawai, but only 8 from the 25 endemic species that occur in natural sites around Brasília. The abundance of four endemic species (D. nebulosa, D. sturtevanti, D. cardini and D. prosaltans) decreased as the grade of urbanization increased. D. immigrans, an exotic species, showed the opposite pattern. We concluded that most endemic species of Drosophilidae are not able to colonize the new environment represented by the city, and that some species of this family may detect not only environmental alteration, by their presence or absence, but also the grade of environmental disturbance, by their relative abundance.     

Ecological restoration and revegetation works in Korea

Korea established foundations for rapid economic growth and national development within a short period of time, but not without incidental problems of degradation to the natural environment. Problems include destruction of ecosystems and reduction of forest area. Nowadays, environment-friendly construction projects are required in Korea for efficient use and preservation of national land. In an effort to protect natural land four types of restoration and preservation plans have been proposed recently. This paper explores the status and value of these efforts and the problems of re-vegetation works on disturbed land in Korea. Korea still gives insufficient attention to species selection for re-vegetation in terms of ecological soundness. In restoring damaged areas, Korea still uses mainly exotic species. As a result, the Ministry of Construction and Transportation is revising design criteria for road slopes in consideration of climate and topography. The Ministry of Environment revised the Natural Environment Conservation Law and uses natural ecological restoration engineers and natural environment management operators as environment restoration specialists. These engineers and sectors specialize in the area of nature in reviews and ecological restoration works. The first national qualifying examination to select natural ecological restoration engineers and natural environment management operators took place in 2004. In an effort to seek systematic conservation for an eco-network, there have been attempts to designate the Baekdu Daegan, which runs south to north along the Korean Peninsula, and the Demilitarised Zone, which traverses east to west, as ecological axes. Efforts to survey the damaged habitats found in the Baekdu Daegan and to develop a restoration plan after designating restoration areas are being made. Moreover, in 2004, the National Assembly passed an Act on the Protection of the Baekdu Daegan Mountain System which will facilitate the designation of Baekdu Daegan into core and buffer areas and therefore its designation as a protected area. The Seoul Metropolitan Government is planning to increase green space in urban areas. In the case of the Cheonggyecheon stream restoration project, which was initiated as part of efforts to restore urban ecosystems, the removal of existing structures is nearing completion. Once it is finished, a highly diverse urban green corridor biosphere reserve will be created along with rooftop re-vegetation. The Seoul Metropolitan government plans to introduce programs to support rooftop re-vegetation projects. Various options are still under consideration or at a pilot stage, but once these efforts become more visible, they are likely to play a positive role in developing and preserving national land in Korea.     

The Use of Habitat Models in Conservation of Rare and Endangered Leafhopper Species (Hemiptera,Auchenorrhyncha)

For conservation of Auchenorrhyncha species, knowledge of their habitat requirements is essential. However, for most species there is no ‘quantitative’ knowledge that would allow e.g. spatially explicit predictions. Such predictions can be made by habitat models, which quantify the relationship between the environment and the occurrence of species. In two plot-based case studies – the endangered leafhopper Verdanus bensoni in mountainous grasslands and four endangered Auchenorrhyncha in urban brownfields – we used habitat models to quantify the habitat requirements of these five species and to exemplify their use for creating habitat suitability maps. In the first case study, the multivariate model showed that occurrence probabilities of the leafhopper V. bensoni increase with both decreasing nitrogen indicator values and decreasing tree cover. On urban brownfields, successional age was a driving factor for species’ occurrence. Site age largely determines a range of vegetation characteristics, which, in multivariate models, often replaced the variable age. Internal validation showed the robustness of all models. The models allow predictions of habitat quality under different management regimes (e.g. response to fertilization or abandonment for V. bensoni or to different turnover rates on brownfield sites). We discuss the application of habitat models in the conservation of Auchenorrhyncha, especially the use of habitat suitability maps.     

Solar ultraviolet-B and photosynthetically active irradiance in the urban sub-canopy: A survey of influences

Stratospheric ozone loss in mid-latitudes is expected to increase the ultraviolet-B (UVB) radiation at the earth's surface. Impacts of this expected increase will depend on many factors, including the distribution of light in other wavelengths. Measurements of the photosynthetically active radiation (PAR) and UVB irradiance were made under clear skies at an open field and under the canopy of scattered trees in a suburban area in W. Lafayette, Indiana, USA (latitude 40.5°). Results showed that when there was significant sky view, the UVB penetration into sub-canopy spaces differs greatly from that of PAR. The UVBT _canopy (transmittance; irradiance below canopy/irradiance in open) was inversely related to sky view. The UVB irradiance did not vary as greatly between shaded and sunlit areas as did PAR. Analysis of measurements made near a brick wall indicated that the leaf area of a canopy and the brick wall primarily acted to block fractions of the sky radiance and contributed little scattered UVB to the horizontal plant. A model was developed to predict the UVB and PART _canopy based on diffuse fraction, sky view, and porosity of the crown(s) through which the beam is penetrating. The model accounted for the UVB and PART _canopy to within 0.13 and 0.05 root mean squared error (RMSE), respectively. Analysis of the errors due to model assumptions indicated that care must be taken in describing the sky radiance distribution, the porosity of trees, the penetration of diffuse radiation through porous trees, and the location of sky-obstructing trees and buildings.     

Fluctuation and synchronization of adults catches of Diaphorina citri Kuwayama (Hemiptera: Liviidae) in urban backyards and commercial citrus plantations

Studies to determine the population fluctuation of Diaphorina citri, vector of Candidatus Liberibacter sp., have been carried out mainly in commercial plantations, whereas less have focused in urban areas and their synchrony. The objectives of this work were to monitor D. citri adult populations in Murraya paniculata (OJ) in urban areas and in Persian lime (LM) orchards, to estimate the effect of some environmental factors and to evaluate the synchronization between these populations. Sampling was performed from September 2012 to August 2014 in Veracruz, México. Five urban areas and five commercial Persian lime plots close to each other were selected. Adult D. citri catches were made monthly with yellow traps. Vegetative shoots, temperature and relative humidity were measured throughout the sampling period. Adults of Diaphorina citri were captured in all the sampling sites throughout the two-years sampling period and the populations were more abundant in summer. Significant factors affecting trap catches were the presence of new shoots and temperature. Temperature and relative humidity enclosed a comfort zone between 26 and 28?°C and 75 to 85% respectively. Cross-correlation values were positive across hosts within the same locations and between locations, regardless of the distance, thus suggesting a spatial synchronization in trap catches. This spatial relationship represents a risk of infestation between host species because of the potential movement and dispersal.     

Changes in the water-permeability of roots of some trees during drought stress and recovery,as related to problems of growth in urban environment

Summary In relation to problems encountered in the urban environment a study was made of changes in the root's permeability to water of a number of tree species during a drought period, and of water conductivity during recovery. The results suggest than an important reduction of water conductivity occurs as soon as internal water stress builds up. Recovery appears to proceed irregularly. There appear to be differences in response — both as regards extent and speed — among different species.     

Strong differences in Quercus robur-associated ectomycorrhizal fungal communities along a forest-city soil sealing gradient

Ectomycorrhizal fungi (EM) that associate with tree roots in a symbiotic relationship may be crucial in mediating tree health in urban environments, but research on the effects of urbanization on EM communities is very limited so far. Here, we compared EM communities of adult pedunculate oaks (Quercus robur) between urban and forest environments, and assessed the effect of soil sealing around the trees on their EM community composition and EM diversity. We sampled 32 oak individuals across 4 sampling classes (Street, Lane, Park and Forest), and we characterized their EM communities using 454 amplicon pyrosequencing. The EM communities were not nested but they were significantly different between all sampling classes, with a very strong community differentiation between forest and urban trees. There were indications that EM richness declined with increasing sealed soil surface, with a significant effect of sampling class on estimated EM richness and diversity. We also identified indicator EM of the different sampling classes. The most important soil factor affecting EM community composition was pH, followed by plant available phosphorus, total nitrogen content and organic matter. Our results may have important implications when developing EM inocula for managing tree health in urban environments.