An individual-based analysis of the dynamics of two coexisting phytoplankton species in the mixed layer

In marine ecosystems ecological and environmental conditions continuously change, possibly supporting the wide range of phytoplankton species coexisting in aquatic environments. Phytoplankton communities are not homogeneously distributed in the water column due to the spatial and temporal variability of turbulent mixing and the concurrent biological response. In this paper an individual-based model (Lagrangian method) simulating the basic physiology of two coexisting phytoplankton species has been developed. The species, sharing the same availability of light and nutrient resource, are characterized by different photo-physiological parameters. The spatial and temporal evolution of turbulent mixing is simulated introducing vertical profiles of measured eddy diffusivity. Three case studies have been examined to analyze the role of environment–individual interactions in determining bloom conditions for both the selected species. The organisms experience recurrent fluctuations of light, temperature, and nutrient concentration gradients, due to the turbulent mixing in the water column, which have significant effects on the growth of the phytoplankton species. In all the numerical experiments, the temporal and spatial variability of different forcings do not support the prevalence of one species over the other over the time scale typical of a phytoplankton bloom.A well mixed water column favours the growth of both the populations while a variable mixing regime limits their growth reducing the photophysiological differences between the species.     

Genotoxicity monitoring of freshwater environments using caged crayfish (Astacus leptodactylus)

Genotoxicity of freshwater pollution was assessed by measuring DNA damage in haemocytes of caged freshwater crayfish Astacus leptodactylus by the means of Comet assay and micronucleus test, integrated with the measurements of physiological (total protein concentration) and immunological (total haemocyte count) haemolymph parameters as biomarkers of undergone stress. Crayfish were collected at the reference site (River Mre?nica) and exposed in cages for 1 week at three polluted sites along the Sava River (Zagreb, Sisak, Krapje). The long term pollution status of these locations was confirmed by chemical analyses of sediments. Statistically significant increase in DNA damage measured by the Comet assay was observed at all three polluted sites comparing to the crayfish from reference site. In addition, native crayfish from the mildly polluted site (Krapje) cage-exposed on another polluted site (Zagreb) showed lower DNA damage than crayfish from the reference site exposed at the same location indicating adaptation and acclimatisation of crayfish to lower levels of pollution. Micronuclei induction showed similar gradient of DNA damage as Comet assay, but did not reach the statistical significance. Observed increase in total haemocyte count and total protein content in crayfish from polluted environments in the Sava River also confirmed stress caused by exposure to pollution. The results of this study have proved the applicability of caging exposure of freshwater crayfish A. leptodactylus in environmental genotoxicity monitoring using Comet assay and micronucleus test.     

Towards the harmonization between National Forest Inventory and Forest Condition Monitoring. Consistency of plot allocation and effect of tree selection methods on sample statistics in Italy

In the frame of a process aiming at harmonizing National Forest Inventory (NFI) and ICP Forests Level I Forest Condition Monitoring (FCM) in Italy, we investigated (a) the long-term consistency between FCM sample points (a subsample of the first NFI, 1985, NFI_1) and recent forest area estimates (after the second NFI, 2005, NFI_2) and (b) the effect of tree selection method (tree-based or plot-based) on sample composition and defoliation statistics. The two investigations were carried out on 261 and 252 FCM sites, respectively. Results show that some individual forest categories (larch and stone pine, Norway spruce, other coniferous, beech, temperate oaks and cork oak forests) are over-represented and others (hornbeam and hophornbeam, other deciduous broadleaved and holm oak forests) are under-represented in the FCM sample. This is probably due to a change in forest cover, which has increased by 1,559,200 ha from 1985 to 2005. In case of shift from a tree-based to a plot-based selection method, 3,130 (46.7 %) of the original 6,703 sample trees will be abandoned, and 1,473 new trees will be selected. The balance between exclusion of former sample trees and inclusion of new ones will be particularly unfavourable for conifers (with only 16.4 % of excluded trees replaced by new ones) and less for deciduous broadleaves (with 63.5 % of excluded trees replaced). The total number of tree species surveyed will not be impacted, while the number of trees per species will, and the resulting (plot-based) sample composition will have a much larger frequency of deciduous broadleaved trees. The newly selected trees have—in general—smaller diameter at breast height (DBH) and defoliation scores. Given the larger rate of turnover, the deciduous broadleaved part of the sample will be more impacted. Our results suggest that both a revision of FCM network to account for forest area change and a plot-based approach to permit statistical inference and avoid bias in the tree sample composition in terms of DBH (and likely age and structure) are desirable in Italy. As the adoption of a plot-based approach will keep a large share of the trees formerly selected, direct tree-by-tree comparison will remain possible, thus limiting the impact on the time series comparability. In addition, the plot-based design will favour the integration with NFI_2.     

PM2.5 exposure as a risk factor for multiple sclerosis. An ecological study with a Bayesian mapping approach

Environmental Science and Pollution Research - Some environmental factors are associated with an increased risk of multiple sclerosis (MS). Air pollution could be a main one. This study was...     

Neuro-fuzzy and neural network systems for air quality control

In order to define efficient air quality plans, Regional Authorities need suitable tools to evaluate both the impact of emission reduction strategies on pollution indexes and the costs of such emission reductions. The air quality control can be formalized as a two-objective nonlinear mathematical problem, integrating source–receptor models and the estimate of emission reduction costs. Both aspects present several complex elements. In particular the source–receptor models cannot be implemented through deterministic modelling systems, that would bring to a computationally unfeasible mathematical problem. In this paper we suggest to identify source–receptor statistical models (neural network and neuro-fuzzy) processing the simulations of a deterministic multi-phase modelling system (GAMES). The methodology has been applied to ozone and PM10 concentrations in Northern Italy. The results show that, despite a large advantage in terms of computational costs, the selected source–receptor models are able to accurately reproduce the simulation of the 3D modelling system.     

PCDD/Fs and dioxin-like PCBs in human milk and estimation of infants' daily intake: a review

This paper reviews the recent scientific literature on PCDDs, PCDFs and dioxin-like PCBs in human milk. All the papers reporting levels of these contaminants in human breast milk published from January 2000 to January 2009 and available on the www.sciencedirect.com web site were identified and included. The aim was (1) to study levels of PCDDs, PCDFs and PCBs in human milk in mothers from different geographical areas and assess infant exposure to these contaminants; (2) to study the effect of variables such as the mother’s age, number of deliveries, dietary and smoking habits and her own nutrition in infancy, and the environment, on levels of the contaminants in breast milk; (3) to study time patterns, and (4) to identify data gaps.     

Fate of para-toluenesulfonamide (p-TSA) in groundwater under anoxic conditions: modelling results from a field site in Berlin (Germany)

This article reports on a field modelling study to investigate the processes controlling the plume evolution of para-toluenesulfonamide (p-TSA) in anoxic groundwater in Berlin, Germany. The organic contaminant p-TSA originates from the industrial production process of plasticisers, pesticides, antiseptics and drugs and is of general environmental concern for urban water management. Previous laboratory studies revealed that p-TSA is degradable under oxic conditions, whereas it appears to behave conservatively in the absence of oxygen (O₂). p-TSA is ubiquitous in the aquatic environment of Berlin and present in high concentrations (up to 38 μg L^?1) in an anoxic aquifer downgradient of a former sewage farm, where groundwater is partly used for drinking water production. To obtain refined knowledge of p-TSA transport and degradation in an aquifer at field scale, measurements of p-TSA were carried out at 11 locations (at different depths) between 2005 and 2010. Comparison of chloride (Cl^?) and p-TSA field data showed that p-TSA has been retarded in the same manner as Cl^?. To verify the transport behaviour under field conditions, a two-dimensional transport model was setup, applying the dual-domain mass transfer approach in the model sector corresponding to an area of high aquifer heterogeneity. The distribution of Cl^? and p-TSA concentrations from the site was reproduced well, confirming that both compounds behave conservatively and are subjected to retardation due to back diffusion from water stagnant zones. Predictive simulations showed that without any remediation measures, the groundwater quality near the drinking water well galleries will be affected by high p-TSA loads for about a hundred years.     

Solar CPC pilot plant photocatalytic degradation of bisphenol A in waters and wastewaters using suspended and supported-TiO2. Influence of photogenerated species

Photocatalytic degradation of bisphenol A (BPA) in waters and wastewaters in the presence of titanium dioxide (TiO₂) was performed under different conditions. Suspensions of the TiO₂ were used to compare the degradation efficiency of BPA (20 mg L^?1) in batch and compound parabolic collector (CPC) reactors. A TiO₂ catalyst supported on glass spheres was prepared (sol–gel method) and used in a CPC solar pilot plant for the photodegradation of BPA (100 μg L^?1). The influence of OH·, O₂ ^·?, and h ⁺ on the BPA degradation were evaluated. The radicals OH· and O₂ ^·? were proved to be the main species involved on BPA photodegradation. Total organic carbon (TOC) and carboxylic acids were determined to evaluate the BPA mineralization during the photodegradation process. Some toxicological effects of BPA and its photoproducts on Eisenia andrei earthworms were evaluated. The results show that the optimal concentration of suspended TiO₂ to degrade BPA in batch or CPC reactors was 0.1 g L^?1. According to biological tests, the BPA LC₅₀ in 24 h for E. andrei was of 1.7?×?10^?2 mg cm^?2. The photocatalytic degradation of BPA mediated by TiO₂ supported on glass spheres suffered strong influence of the water matrix. On real municipal wastewater treatment plant (MWWTP) secondary effluent, 30 % of BPA remains in solution; nevertheless, the method has the enormous advantage since it eliminates the need of catalyst removal step, reducing the cost of treatment.     

Exergy and extended exergy accounting of very large complex systems with an application to the province of Siena, Italy

This paper describes the application of exergy and extended exergy analyses to large complex systems. The system to be analysed is assumed to be at steady state, and the input and output fluxes of matter and energy are expressed in units of exergy. Human societies of any reasonable extent are indeed Very Large Complex Systems and can be represented as interconnected networks of N elementary "components", their Subsystems; the detail of the disaggregation depends on the type and quality of the available data. The structural connectivity of the "model" of the System must correctly describe the interactions of each mass or energy flow with each sector of the society: since it is seldom the case that all of these fluxes are available in detail, some preliminary mass- and energy balances must be completed and constitute in fact a part of the initial assumptions. Exergy accounting converts the total amount of resources inflow into their equivalent exergetic form with the help of a table of "raw exergy data" available in the literature. The quantification of each flow on a homogeneous exergetic basis paves the way to the evaluation of the efficiency of each energy and mass transfer between the N sectors and makes it possible to quantify the irreversible losses and identify their sources. The advantage of the EEA, compared to a classical exergy accounting, is the inclusion in the system balance of the exergetic equivalents of three additional "Production Factors": human Labour, Capital and Environmental Remediation costs. EEA has an additional advantage: it allows for the calculation of the efficiency of the domestic sector (impossible to evaluate with any other energy- or exergy-based method) by considering the working hours as its product. As implied in the title, an application of the method was made to a model of the province of Siena (on a year 2000 database): the results show that the sectors of this Province have values of efficiency close to the Italian average, with the exception of the commercial and energy conversion sectors that are more efficient, in agreement with the rather peculiar socio-economic situation of the Province. The largest inefficiency is found to be in the transportation sector, which has an efficiency lower then 30% in EEA and lower than 10% in classical exergy accounting.     

Heavy precipitation events over the Euro-Mediterranean region in a warmer climate: results from CMIP5 models

Possible changes in the intensity of heavy precipitation events at the end of the twenty-first century over the Euro-Mediterranean region are investigated, using a subset of numerical climate simulations taking part to the fifth phase of the Coupled Model Intercomparison Project (CMIP5). As a measure of the intensity associated with heavy precipitation events, we use the difference between the 99th and the 90th percentiles. Despite a slight tendency to underestimate the observed heavy precipitation intensity during summer and to overestimate it during winter, the considered CMIP5 models well represent the observed patterns of the defined 99th–90th percentile metric during both seasons for the 1997–2005 period over the Euro-Mediterranean region. Over the investigated domain, an increase of the width of the right tail of the precipitation distribution is projected in a warmer climate, even over regions where nearly the entire precipitation distribution becomes dryer. This is the case of the European domain within the 45N–55N belt.