磁场对静态纳滤过程的膜通量及CaCO3结晶的影响

使用NF270型和NF型纳滤膜研究了经磁化预处理的钙溶液的静态纳滤过程,并与未经磁化预处理钙溶液的静态纳滤结果相比较.结果表明,当水样中Ca²⁺ 浓度为3.6 mmol/L,硬度等于碱度,初始水样体积为300 mL,体积浓缩倍数为2时,普通溶液的膜通量随滤出液体积呈现单调递减趋势;但处理磁化溶液时,膜通量随滤出液的体积先下降后上升,然后才下降,且平均膜通量比普通溶液的高,表明磁化预处理可以改善纳滤膜的部分操作性能.对膜的扫描电镜分析表明,处理磁化溶液的纳滤膜膜面上生成的晶体相对较多.综合纳滤膜通量和膜面晶体生成量的观察,认为磁场的引入可使膜表面结晶速率增加,致使膜面溶质浓度降低,通量上升,同时因生成的晶体全部留在膜面上,运行一段时间后有效膜面积减少,又导致通量下降.晶体生成量较多的膜,通量却相对较高,这与平常对膜污染的认识相矛盾.通过对结晶过程的理论分析,认为一定程度的结晶对膜操作性能有改善作用.     

Bioavailability and accumulation of trace elements in soils and plants of a highly contaminated estuary (Domingo Rubio tidal channel,SW Spain)

The Domingo Rubio tidal channel (Palos de la Frontera, Huelva, Spain) is an estuary located in the mouth of the Tinto River. The estuary is affected by different sources of pollution (waters of the Tinto River, contaminated with trace elements from the Iberian Pyrite belt, and effluent from the Huelva chemical industrial area). Soil and the most frequent plant species were collected in 2004 and 2006 at six different locations on the estuary. In general, N-Kjedahl, Total Organic Carbon values, salinity and contamination (total trace elements up to 1,000 mg kg⁻¹ As, 6 mg kg⁻¹ Cd, 2,500 mg kg⁻¹ Cu, 1,900 mg kg⁻¹ Pb and 1,300 mg kg⁻¹ Zn) tended to increase downstream of the tidal channel. Soil biochemical properties were not negatively affected either by the high salinity or by trace element contamination. Despite the high values of the trace elements, analysed plant samples showed that Cu was the only metal that could be a serious risk for the food chain.     

Trophic field overlap: A new approach to quantify keystone species

It is a current challenge to better understand the relative importance of species in ecosystems, and the network perspective is able to offer quantitative tools for this. It is plausible to assume, in general, that well-linked species, being key interactors, are also more important for the community. Recently a number of methods have been suggested for quantifying the network position of species in ecological networks (like the topological importance metric, TI). Most of them are based on node centrality indices and it may happen that the two most important species in a food web have very similar interaction structure and they can essentially replace each other if one becomes extinct. For conservation considerations it is a challenge to identify species that are richly connected and, at the same time, have a relatively unique and irreplaceable interaction pattern. We present a new method and illustrate our approach by using the Kuosheng Bay trophic network in Taiwan. The new method is based on the interaction matrix, where the strength of the interaction between nodes i and j depends only on topology. By defining a threshold separating weak and strong interactors, we define the effective range of interactions for each graph node. If the overlaps between pairs of these ranges are quantified, we gain a metric expressing how unique is the interaction pattern of a focal node (TO). The combination of centrality (TI) and uniqueness (TO) is called topological functionality (TF). We compare the nodal importance rank provided by this metric to others based on a variety of centrality measures. The main conclusion is that shrimps seem to have the most unique interaction pattern despite that their structural importance has been underestimated by all conventional centrality indices. Also, our network analysis suggests that fisheries disturb the ecosystem in a more critical network position than the impingement by the local power plant.     

A jellyfish diet for the herbivorous green turtle Chelonia mydas in the temperate SW Atlantic

Feeding ecology of juvenile green turtles (Chelonia mydas) was studied from 2008 to 2011 at Samborombón Bay (35°30′–36°30′S, Argentina), combining data on digestive tract examination and stable isotope analysis through a Bayesian mixing model. We found that animal matter, in particular gelatinous plankton, was consumed in large proportions compared to herbivorous food items such as terrestrial plants and macroalgae. This diet is facilitated by the high abundance of gelatinous plankton in the region, thus confirming the adaptive foraging behaviour of the juveniles according to prey abundance in the SW Atlantic. To our knowledge, this is the first study to employ this combination of techniques and to conclusively demonstrate that animal matter, in particular gelatinous plankton, is important in the diet of the neritic green sea turtles.     

Sources and spatial distribution of polycyclic aromatic hydrocarbons in coastal sediments of the Basque Country (Bay of Biscay)

This contribution characterises the sources and distribution of polycyclic aromatic hydrocarbons (PAHs) in sediments of the Basque coast (Bay of Biscay). Different source characterisation approaches (i.e. GIS assisted-chemometrics, PAH diagnostic ratios and analyses of composition profiles) were used in combination to successfully identify the factors determining the origin and distribution of PAHs. Urban/industrial combustion processes were identified as the main PAH source. However, the analysis of PAH composition patterns and diagnostic ratios identified secondary natural and petrogenic PAH sources on small spatial scales. The median ∑18PAH concentration ranged from 66 μg kg^?1 (d.w.) to 7021 μg kg^?1 (d.w.). The Ibaizabal estuary, which supports most of the anthropogenic pressure in the region (i.e. urban development, industrialisation, commercial and recreational harbours), also showed the highest PAH concentrations. On the shelf, human activities, hydrodynamic conditions and geomorphological features led to spatial differences in the PAH concentrations among sectors: the offshore and west sectors were characterised by higher concentrations, while the lowest values were found in the mid and east sectors. The results enhance the knowledge on PAH-related contamination processes and could be used to support the environmental assessment process required under current European marine legislation.     

Filial cannibalism in a nest-guarding fish: females prefer to spawn in nests with few eggs over many

In fish, fecundity correlates with female body size and egg-tending males often eat small broods. Therefore, small females may prefer to spawn in nests that already contain many eggs, to ensure the brood is as large as possible. In contrast, large females may prefer nests with few eggs, if high egg number or density has a negative effect on egg survival, or if there are drawbacks of spawning last in a nest. To test the hypothesis that female body size affects nest (and male mate) choice, using the sand goby (Pomatoschistus minutus), we allowed small and large females to choose between two males that were matched in size — one guarding a small clutch and the other a large clutch, respectively. We recorded where females spawned (measure of female preference), the combined brood size, male courtship, egg care and nest building. We also quantified the effect of brood size and egg density on egg survival in a separate data set. Although the combined broods did not exceed the small brood sizes that are at risk of being eaten, both small and large females preferred to spawn in nests with smaller clutch sizes. This preference could not be explained by more courtship or male parental effort, nor by reduced survival of larger or denser broods. Instead, our result might be explained by females avoiding the danger of cannibalism of young eggs by males or the risk of reduced egg health associated with being near the nest periphery.     

Analytical solutions of nonlinear and variable-parameter transport equations for verification of numerical solvers

All numerical codes developed to solve the advection–diffusion-reaction (ADR) equation need to be verified before they are moved to the operational phase. In this paper, we initially provide four new one-dimensional analytical solutions designed to help code verification; these solutions are able to handle the challenges of the scalar transport equation including nonlinearity and spatiotemporal variability of the velocity and dispersion coefficient, and of the source term. Then, we present a solution of Burgers’ equation in a novel setup. Proposed solutions satisfy the continuity of mass for the ambient flow, which is a crucial factor for coupled hydrodynamics-transport solvers. By the end of the paper, we solve hypothetical test problems for each of the solutions numerically, and we use the derived analytical solutions for code verification. Finally, we provide assessments of results accuracy based on well-known model skill metrics.     

The evaluation of ecology-based tourism potential in coastal villages in accordance with landscape values and user demands: the Bursa-Mudanya-Kumyaka case

Ecology-based tourism, which is integrated with nature, developed in environmentally conscious areas and enriched by different cultures, has become more important in the direction of extending tourism throughout the year. While the landscape values of the area are important functions for tourism activities to be carried out in natural characteristics, the preferences of the users are also important. Ecology-based tourism, which develops in connection with the concepts of intacteness, the protection-use balance and sustainability, and the demands and expectations of tourists, constitute the basis of our study. For this purpose, the study was carried out in Kumyaka, a small coastal neighborhood (village) of the county of Mudanya in the province Bursa, Turkey with important natural, historical and cultural assets. Fieldwork, field analysis, literature search, interviews with tourists coming to the field, interviews with the day trippers and survey work were conducted in the study. While evaluating the ecology-based tourism potential of the area, the demands and expectations of tourists have been taken into account together with the available area data. According to the results of the survey, tourists are mostly interested in having the most scenic value and quietness when choosing the area. The types of tourism that tourists most wanted to experience in the field were 42.38% culture tourism and 32.32% nature tourism. As a result of tourists’ demands and expectations, the tourism activities to be carried out in accordance with the possibilities of the area were examined and ecology based planning proposals and holistic planning approaches were developed.     

Effects of three biochars on copper immobilization and soil microbial communities in a metal-contaminated soil using a metallophyte and two agricultural plants

Environmental Geochemistry and Health - Biochar (BC) is a porous, carbonaceous material produced by slow pyrolysis of biomass under oxygen-limited conditions. BC production has been attracting...     

Trace element contents in fine particulate matter (PM<Subscript>2.5</Subscript>) in urban school microenvironments near a contaminated beach with mine tailings,Chañaral,Chile

Air quality in schools is an important public health issue because children spend a considerable part of their daily life in classrooms. Particulate size and chemical composition has been associated with negative health effects. We studied levels of trace element concentrations in fine particulate matter (PM_2.5) in indoor versus outdoor school settings from six schools in Chañaral, a coastal city with a beach severely polluted with mine tailings. Concentrations of trace elements were measured on two consecutive days during the summer and winter of 2012 and 2013 and determined using X-ray fluorescence. Source apportionment and element enrichment were measured using principal components analysis and enrichment factors. Trace elements were higher in indoor school spaces, especially in classrooms compared with outdoor environments. The most abundant elements were Na, Cl, S, Ca, Fe, K, Mn, Ti, and Si, associated with earth’s crust. Conversely, an extremely high enrichment factor was determined for Cu, Zn, Ni and Cr; heavy metals associated with systemic and carcinogenic risk effects, whose probably origin sources are industrial and mining activities. These results suggest that the main source of trace elements in PM_2.5 from these school microenvironments is a mixture of dust contaminated with mine tailings and marine aerosols. Policymakers should prioritize environmental management changes to minimize further environmental damage and its direct impact on the health of children exposed.