Hg transfer from contaminated soils to plants and animals

Understanding the transfer of mercury (Hg) from soil to crops is crucial due to Hg toxicity and Hg occurrence in terrestrial systems. Previous research has shown that available Hg in soils contributes to plant Hg levels. Plant Hg concentrations are related to soil conditions and plant characteristics. Mechanistic models describing such soil–plant interactions are however difficult to quantify. Here we performed a field study in agricultural, mining and industrial areas in Portugal to evaluate potential food chain risks. The uptake of Hg by Italian ryegrass, ryegrass, orchard grass, collard greens and rye was measured to calculate daily intakes (DI) of Hg for cows and sheep grazing. A total of 136 soil samples and 129 plant samples were analysed. Results show that total Hg concentrations ranged from 0.01 to 98 mg kg⁻¹ in soils; 0.01–5.4 mg kg⁻¹ in shoots and 0.01–42 mg kg⁻¹ in roots. Calculated DI ranged from 0.18 to 132 mg d⁻¹ for cows, and from 0.028 to 23 mg d⁻¹ for sheep. In 27 grassland sites, daily intakes exceeded the acceptable daily intake of both cows and sheep in view of food safety considering Hg in animal kidneys evidencing potential risks to human health. The transfer of Hg from soil to crops was described using empirical Freundlich-type functions. For ryegrass, orchard grass and collard greens, the soil-to-root or soil-to-shoot transfer of Hg appeared to be controlled by the total soil Hg concentration and levels of Al_ox and Fe_ox. Empirical functions allowed us to obtain realistic estimates of Hg levels in crops and can be used as an alternative to mechanistic models when evaluating food chain risks of Hg contamination in agricultural soils.     

Risk assessment of coastal flood in a site of special scientific interest

The Canary Islands have a long coastline with varying levels of exposure to severe sea conditions. Frequent states of alert and emergency in some parts of their coastline are commonly related to the occurrence of extreme wave conditions. Among the phenomena directly driven by the waves when reaching the shore are the wave run-up and overtopping. Both the study of the flood level, including its variability, and the associated risks are key tools in the planning and management of coastal zones. The aim of this research is to examine the probability of occurrence of run-up events capable of exceeding different topographical levels, for estimating the risk level associated with flooding of the different areas in which the Boca Barranco Beach can be divided, in terms of their nature and use. This beach is located on the island of Gran Canaria, Spain, and is part of the site of scientific interest of Jinámar. A large wave dataset is used as input to a high-resolution numerical model for propagating offshore wave conditions to shallow waters in the study area. Furthermore, the morphology of the study area is reproduced by combining different bathymetric databases. Finally, the probability of occurrence of different levels of run-up and the corresponding levels of consequences are assigned, to assess the flood risk in the different areas of the beach, which are presented in a risk map of flooding in the study area.     

Synthesis of grafted natural pozzolan with 3-aminopropyltriethoxysilane: preparation,characterization, and application for removal of Brilliant Green 1 and Reactive Black 5 from aqueous solutions

Environmental Science and Pollution Research - Natural pozzolan is an amorphous silicate-based material of volcanic origin. In this work, the natural pozzolan was modified by using...     

Land cover classification with an expert system approach using Landsat ETM imagery: a case study of Trabzon

The main objective of this study is to generate a knowledge base which is composed of user-defined variables and included raster imagery, vector coverage, spatial models, external programs, and simple scalars and to develop an expert classification using Landsat 7 (ETM+) imagery for land cover classification in a part of Trabzon city. Expert systems allow for the integration of remote-sensed data with other sources of geo-referenced information such as land use data, spatial texture, and digital elevation model to obtain greater classification accuracy. Logical decision rules are used with the various datasets to assign class values for each pixel. Expert system is very suitable for the work of image interpretation as a powerful means of information integration. Landsat ETM data acquired in the year 2000 were initially classified into seven classes for land cover using a maximum likelihood decision rule. An expert system was constructed to perform post-classification sorting of the initial land cover classification using additional spatial datasets such as land use data. The overall accuracy of expert classification was 95.80%. Individual class accuracy ranged from 75% to 100% for each class.     

Modelling feeding flow related shrinkage defects in aluminum castings

The process modelling of shape casting is geometrically complex and computationally very challenging. Besides the three-dimensional complex shapes with multiple domains, the defects of interest to industry arise as a consequence of the interaction amongst a range of phenomena. Conventionally, the key phenomena and defect prediction are modelled through empirical relations applied to the simulation results. Such approaches are neither comprehensive nor reliable. This paper presents a 3-D model that is capable of predicting the formation of shrinkage defects explicitly as a function of the interacting continuum phenomena, i.e. free surface flow, heat transfer, and solidification, in complex three-dimensional geometries which allows to identify the distinction between surface depression, surface connected cavities and internal cavities.The model solves the coupled macroscopic conservation equations for mass, momentum, and energy with a phase change during solidification. In the model, the volume deficit due to solidification can either be compensated by depression of the outside surface or by creating a cavity that initiates either on the surface or in the interior of the casting. The solidification morphology is taken into account by using a parameter, which depends on the fraction solid, in the momentum equation. By using an adapted free surface algorithm, it is suitable to predict surface connected defects: depressed surfaces and caved surfaces. A critical pressure serves as a criterion to open internal shrinkage cavities. The model does not need to search for connected zones to feed shrinkage, but the shrinkage distribution will automatically emerge from the continuity equation.This advanced shrinkage model has experimentally been validated successfully using two Al-Si alloys, a skin freezing eutectic alloy and a mushy freezing hypo-eutectic alloy.     

Environmental benefits of using sewage sludge in the production of ceramic bricks

Environmental Science and Pollution Research - The production of sludge from the sewage treatment plants is increasing as a result of population increase and public policies to improve the...     

Effects of land-use changes on landslides in a landslide-prone area (Ardesen, Rize, NE Turkey)

Various natural hazards such as landslides, avalanches, floods and debris flows can result in enormous property damages and human casualties in Eastern Black Sea region of Turkey. Mountainous topographic character and high frequency of heavy rain are the main factors for landslide occurrence in Ardesen, Rize. For this reason, the main target of the present study is to evaluate the landslide hazards using a sequence of historical aerial photographs in Ardesen (Rize), Turkey, by Photogrammetry and Geographical Information System (GIS). Landslide locations in the study area were identified by interpretation of aerial photographs dated in 1973 and 2002, and by field surveys. In the study, the selected factors conditioning landslides are lithology, slope gradient, slope aspect, vegetation cover, land class, climate, rainfall and proximity to roads. These factors were considered as effective on the occurrence of landslides. The areas under landslide threat were analyzed and mapped considering the landslide conditioning factors. Some of the conditioning factors were investigated and estimated by employing visual interpretation of aerial photos and topographic data. The results showed that the slope, lithology, terrain roughness, proximity to roads, and the cover type played important roles on landslide occurrence. The results also showed that degree of landslides was affected by the number of houses constructed in the region. As a consequence, the method employed in the study provides important benefits for landslide hazard mitigation efforts, because a combination of both photogrammetric techniques and GIS is presented.     

Median lethal concentration of formaldehyde and its genotoxic potential in bullfrog tadpoles (Lithobates catesbeianus)

In order to avoid that contaminated frog farms animals escaping in the environment and become potential vector of emergent diseases, studies with disinfection protocol are strictly necessary. The formaldehyde is one of the compounds tested in fungal disinfection protocols and also used in aquaculture. This study aimed to determine the median lethal concentration (LC_50–96h) of formaldehyde in bullfrog tadpoles and to evaluate the possible genotoxic effects in acute exposition. Accordingly, the animals were exposed to formaldehyde in the concentrations of 6, 9, 12, 15, and 18 mg L^?1, and after 96 h blood samples were drawn for the micronucleus (MN) test. The LC_50–96h was 10.53 mg L^?1, and the MN frequency increased in proportion to the formaldehyde concentrations, with an estimated frequency in the negative control being 1.35 MN/individual. We concluded that formaldehyde is genotoxic to tadpoles of bullfrogs in the tested concentrations, and the choice of this chemical should be contemplated before its use in animals in captivity.     

Energy conservation and CO2 emission reductions due to recycling in Brazil

The present paper aims to make the energy saving potential provided by waste recycling in Brazil evident by pointing out more specifically the benefits regarding climate change mitigation. In this case, based on the energy saved due to the recycling process of an exogenous amount of waste, we have built two scenarios in order to show the potential for indirectly avoiding CO2 emissions in the country as a result of the recycling process. According to the scenario, 1 Mt and 3.5 Mt of CO2, respectively, would be avoided per year due to solid waste recycling. The international context for greenhouse gas emissions reduction, such as the United Nations Framework Convention on Climate Change and its Kyoto Protocol has been taken into account.