Soil fertility dynamics in runoff-capture agriculture, Canary Islands, Spain

In the extremely arid (∼150 mm yr⁻¹) eastern Canary Islands of Lanzarote, Fuerteventura and La Graciosa, agriculture has been sustained for decades by a traditional runoff-capture (RC) farming system known as “gavias”. Although the main goal of these systems is to increase water supply for crops, making unnecessary conventional irrigation, a secondary and equally important factor is that this system allows for sustainable agricultural production without addition of chemical or organic fertilizers. A field study was conducted to assess the impact of long-term agriculture (>50 yr) on soil fertility and to evaluate key factors affecting the nutrient sustainability of RC agricultural production. Soil fertility and nutrient dynamics were studied through chemical characterization of the arable layer (0-25 cm) of RC agricultural plots, adjacent natural soils (control) not affected by runoff and cultivation, and sediments contributed by a series of RC events. Results showed that RC soils have enhanced fertility status, particularly because they are less affected by salinity and sodicity (mean electrical conductivity = 1.8 dS m⁻¹ vs. 51.0 dS m⁻¹ in control soils; mean exchangeable sodium percentage = 11.1% vs. 30.6% in control soils), and have higher water and nutrient holding capacities (mean clay plus silt contents ≈87% vs. 69% in control soils). In general, sediments transported with the runoff and deposited in RC plots (average sediment yield ≈ 46 ton ha⁻¹ yr⁻¹), contain sufficient nutrients to prevent a progressive reduction of essential plant nutrients below natural levels in spite of nutrient uptake and removal by the harvested crop. Average additions of nitrogen, phosphorus and potassium with the runoff sediments were 33.6, 35.3 and 48.8 kg ha⁻¹ yr⁻¹, respectively. Results of this study show how a crop production system can be sustained in the long term by natural hydrological and biogeochemical catchment processes. This system maintains a nutrient balance that is not based on energy-intensive inputs of fertilizers, but is integrated in natural nutrient cycling processes, unlike other tropical farming agroecosystems.     

Sustainability issues in sheet metal forming processes: an overview

Environmental sustainability in manufacturing is nowadays an urgent and remarkable issue and the main concerns are related to more efficient use of materials and energy.In sheet metal forming processes there is still a lack of knowledge in this field mainly due to the need of a proper modelling of sustainability issues and factors to be taken into account. The aim of this paper is mainly to underline the state of the art from a forming point of view about the sustainability contributions offered in any phase of a product life cycle. Actually, a lack in terms of comprehensive contributions is present in the technical literature, thus, the authors try to give a sort of holistic vision aimed to provide basic guidelines in order to help in identifying the possible solutions with regard to all the phases of a forming product life cycle. The main attention was paid to sheet metal forming technologies. The paper gives an overview of the main topics concerning sheet metal forming problems related to energy and resource efficiency with the aim to stress the principal contributions which may derive from such processes to environmental performances of manufacturing.     

Environmental and economic assessment of a greenhouse waste heat exchange

As the economic costs of energy and the negative externalities associated with the combustion of fossil fuels threaten the economic viability of greenhouses in northern climates there is a renewed interest in the use of waste heat. This paper presents a technical and economic methodology to determine the viability of establishing waste heat greenhouses using the waste heat from industrial processes in northern climates. A case study is presented of an exchange between a tomato greenhouse and a flat glass manufacturing plant, which found the waste heat system is significantly more economic to operate than a purely natural gas system.     

Recycling of FRP composites: reusing fine GFRP waste in concrete mixtures

Fibre reinforced polymer (FRP) materials are being increasingly used in several applications, but especially in the construction and transportation industries. The composites industry is now producing a wide range of FRP products that include strengthening strips and sheets, reinforcing bars, structural profiles, sandwich panels, moulded planks and piping. The waste management of FRP materials, in particular those made with thermosetting resins, is a critical issue for the composites industry because these materials cannot be reprocessed. Therefore, most thermosetting FRP waste is presently sent to landfill, in spite of the significant environmental impact caused by disposing of it in this way. Because more and more waste is being produced throughout the life cycle of FRPs, innovative solutions are needed to manage it. This paper first presents a state-of-the-art review of the present alternatives available to manage FRP waste. It then describes an experimental study conducted on the technical feasibility of incorporating the fine waste generated during the manufacturing of glass fibre reinforced polymer (GFRP) composites in concrete mixtures. Tests were carried out to evaluate the fresh-state and hardened-state properties of concrete mixes in which between 0% and 20% of sand was replaced by GFRP fine waste. Although the incorporation of high proportions of GFRP waste was found to worsen concrete performance in terms of both mechanical and durability-related properties, it seems feasible to incorporate low proportions and reuse GFRP fine waste in concrete, particularly in non-structural applications such as architectural concrete or pavement slabs, where good mechanical properties are less important.     

Petroleum hydrocarbon concentrations in eight mollusc species along Tamilnadu coast, Bay of Bengal, India

Eight mollusc species and sediment samples collected from three different stations along Tamilnadu coast, Bay of Bengal, India were analysed for the levels of petroleum hydrocarbons to elucidate the status of the petroleum residues in mollusc meant for human consumption. The concentrations of petroleum hydrocarbons in sediments along Tamilnadu coast varied from 5.04–25.5 g/g dw (dry weight). High concentration of petroleum hydrocarbons in the sediment of Uppanar estuary (25.5 1.45 g/g dw) was perhaps land and marine based anthropogenic sources of this region. The petroleum hydrocarbon residues in eight mollusc species collected from Uppanar, Vellar and Coleroon estuaries varied between 2.44–6.04 g/g ww (wet weight). Although the concentration of petroleum hydrocarbons in sediment of the Uppanar region was markedly higher than the background, the petroleum hydrocarbon residues in mollusc collected from Uppanar estuary did not suggest bioaccumulation. The results signified that industrial growth has affected the aquatic environments and regular monitoring will help to adopt stringent pollution control measures for better management of the aquatic region.     

Applying 3DCE to environmentally responsible manufacturing practices

A review of recent literature in the fields of operations, supply chain, and management indicates there is on-going interest in improving new product development (NPD) performance. Three-dimensional concurrent engineering (3DCE), the simultaneous design of product, process and supply chain have been proposed as a way to improve traditional NPD outcomes, such as reduced time to market, lower costs, and improved customer acceptance. There appears to be a lesser concern associated with the environmental impacts of new products. Environmentally responsible manufacturing (ERM) on new product development focuses on reduced emissions, hazardous materials elimination, and lower product weight without sacrificing functionality. This paper explores the following issue: will employing 3DCE to integrate NPD and ERM yield better benefits than the separate and uncoordinated application of environmental goals and NPD initiatives?     

Building Greater Sustainability in Supply Chains

Challenges companies face and tools they use to identify and reduce their environmental footprints across their supply chains     

Sex-specific temperature dependence of foraging and growth of intertidal snails

Predicting the biological impacts of climate change requires an understanding of how temperature alters organismal physiology and behavior. Given differences in reproductive physiology between sexes, increases in global temperature may be experienced differently by the males and females of a species. This study tested for sex-specific effects of increased air temperature on foraging, growth, and survival of an intertidal snail, Nucella ostrina (San Juan Island, Washington, 48–30′44″N, 123–08′43″W). Snails exhibited periodic peaks in foraging. Subjecting snails to elevated low tide air temperatures did not alter the timing or magnitude of this pattern. Despite similar temporal patterns in foraging, females foraged more than males, even when the risk of thermal stress was high. While males and females appear to have a similar body temperature threshold for optimal growth, females were more likely to cross that threshold resulting in a loss of body mass when exposed to daily increases in air temperature. These results suggest that the consequences of a warming climate in the short term may be different for males and females of N. ostrina, but also imply longer-term costs of reduced reproductive output, abundance, and distribution of this ubiquitous intertidal predator. Generally, this study points to the possible significance of sex-specific responses in an increasingly warm world.     

Implications of geometric plasticity for maximizing photosynthesis in branching corals

Reef-building corals are an example of plastic photosynthetic organisms that occupy environments of high spatiotemporal variations in incident irradiance. Many phototrophs use a range of photoacclimatory mechanisms to optimize light levels reaching the photosynthetic units within the cells. In this study, we set out to determine whether phenotypic plasticity in branching corals across light habitats optimizes potential light utilization and photosynthesis. In order to do this, we mapped incident light levels across coral surfaces in branching corals and measured the photosynthetic capacity across various within-colony surfaces. Based on the field data and modelled frequency distribution of within-colony surface light levels, our results show that branching corals are substantially self-shaded at both 5 and 18 m, and the modal light level for the within-colony surface is 50 μmol photons m^?2 s^?1. Light profiles across different locations showed that the lowest attenuation at both depths was found on the inner surface of the outermost branches, while the most self-shading surface was on the bottom side of these branches. In contrast, vertically extended branches in the central part of the colony showed no differences between the sides of branches. The photosynthetic activity at these coral surfaces confirmed that the outermost branches had the greatest change in sun- and shade-adapted surfaces; the inner surfaces had a 50 % greater relative maximum electron transport rate compared to the outer side of the outermost branches. This was further confirmed by sensitivity analysis, showing that branch position was the most influential parameter in estimating whole-colony relative electron transport rate (rETR). As a whole, shallow colonies have double the photosynthetic capacity compared to deep colonies. In terms of phenotypic plasticity potentially optimizing photosynthetic capacity, we found that at 18 m, the present coral colony morphology increased the whole-colony rETR, while at 5 m, the colony morphology decreased potential light utilization and photosynthetic output. This result of potential energy acquisition being underutilized in shallow, highly lit waters due to the shallow type morphology present may represent a trade-off between optimizing light capture and reducing light damage, as this type morphology can perhaps decrease long-term costs of and effect of photoinhibition. This may be an important strategy as opposed to adopting a type morphology, which results in an overall higher energetic acquisition. Conversely, it could also be that maximizing light utilization and potential photosynthetic output is more important in low-light habitats for Acropora humilis.     

Performance,combustion and emission characteristics of a single-cylinder,four-stroke,direct injection diesel engine operated on a dual-fuel mode using Honge oil methyl ester and producer gas derived from biomass feedstock of different origin

Renewable and alternative fuels have numerous advantages compared with fossil fuels, as they are renewable and biodegradable, and provide food and energy security and foreign exchange savings besides addressing environmental concerns and socio-economic issues. In this context, present work was carried out to investigate the feasibility of alternative and renewable fuels derived from biomass feedstock of different origin for engine applications. The present study was also extended to study the effect of producer gas composition derived from different biomass feedstock on the performance, combustion and emission characteristics of a single-cylinder, four-stroke, direct injection stationary diesel engine operated on a dual-fuel mode using Honge oil methyl ester (HOME) and producer gas induction. The performance of the engine was evaluated with a constant injection timing of 27° before top dead centre, an injection pressure of 205 bar for the diesel–producer gas combination and 230 bar for the HOME–producer gas combination and a compression ratio of 17.5. The results showed that the performance of the dual-fuel engine varies with the composition of the producer gas and depends on the type of biomass feedstock used in the gasifier. Experimental investigations on the dual-fuel engine showed that brake thermal efficiency values for the engine operated using HOME–producer gas derived from babul, neem and honge woods were found to be 17.2, 14.3 and 11.56% respectively, compared to 23.8% for diesel–producer gas operation at 80% load. However, the results showed better engine performance with lower exhaust emission levels for the operation of HOME–producer gas derived from the ordinary or babul wood compared with the operation of that derived from the neem and Honge woods. In view of this, present study reveals that use of alternative and renewable fuels for dual fuel engine can be considered as an immediate solution for the development of rural areas and emergency use in the event of severe diesel fuel shortage.