SciCombinator

Discover the most talked about and latest scientific content & concepts.

Journal: Journal of environmental management

42

Organic farming practices have been promoted as, inter alia, reducing the environmental impacts of agriculture. This meta-analysis systematically analyses published studies that compare environmental impacts of organic and conventional farming in Europe. The results show that organic farming practices generally have positive impacts on the environment per unit of area, but not necessarily per product unit. Organic farms tend to have higher soil organic matter content and lower nutrient losses (nitrogen leaching, nitrous oxide emissions and ammonia emissions) per unit of field area. However, ammonia emissions, nitrogen leaching and nitrous oxide emissions per product unit were higher from organic systems. Organic systems had lower energy requirements, but higher land use, eutrophication potential and acidification potential per product unit. The variation within the results across different studies was wide due to differences in the systems compared and research methods used. The only impacts that were found to differ significantly between the systems were soil organic matter content, nitrogen leaching, nitrous oxide emissions per unit of field area, energy use and land use. Most of the studies that compared biodiversity in organic and conventional farming demonstrated lower environmental impacts from organic farming. The key challenges in conventional farming are to improve soil quality (by versatile crop rotations and additions of organic material), recycle nutrients and enhance and protect biodiversity. In organic farming, the main challenges are to improve the nutrient management and increase yields. In order to reduce the environmental impacts of farming in Europe, research efforts and policies should be targeted to developing farming systems that produce high yields with low negative environmental impacts drawing on techniques from both organic and conventional systems.

Concepts: Agriculture, Soil, Nitrogen, Organic farming, Sustainable agriculture, Humus, Crop rotation, Industrial agriculture

28

The genus Populus, which includes poplars, cottonwoods and aspen trees, represents a huge natural source of fibers with exceptional physical properties. In this study, the oil absorption properties of poplar seed hair fibers obtained from Populus nigra italica when tested with high-density motor oil and diesel fuel are reported. Poplar seed hair fibers are hollow hydrophobic microtubes with an external diameter between 3 and 12μm, an average length of 4±1mm and average tube wall thickness of 400±100nm. The solid skeleton of the hollow fibers consists of lignocellulosic material coated by a hydrophobic waxy coating. The exceptional chemical, physical and microstructural properties of poplar seed hair fibers enable super-absorbent behavior with high absorption capacity for heavy motor oil and diesel fuel. The absorption values of 182-211g heavy oil/g fiber and 55-60g heavy oil/g fiber for packing densities of 0.005g/cm(3) and 0.02g/cm(3), respectively, surpass all known natural absorbents. Thus, poplar seed hair fibers obtained from Populus nigra italica and other trees of the genus Populus are an extremely promising natural source for the production of oil super absorbents.

Concepts: Petroleum, Aspen, Populus, Populus tremula, Trees, Populus alba, Populus tremuloides, Populus grandidentata

28

The 2010 British Petroleum (BP) Deepwater Horizon oil spill highlighted long-standing questions about energy exploration and its social and environmental implications. Sociologists studying environmental disasters have documented the social impacts resulting from these events and dissatisfaction with government and industry responses. In this paper, we use data from a survey conducted during the Gulf of Mexico oil spill to examine how Louisiana and Florida residents' social backgrounds, experiences with the spill, and trust in information sources predict their perceptions of governmental and BP response efforts. We find that direct personal impacts and compensation strongly influence the evaluations of responding organizations. Age and place of residence also predict such assessments. Finally, levels of confidence in television news and BP as sources of information appear to shape Gulf Coast residents' opinions about the work of organizations responding to the Deepwater Horizon disaster.

Concepts: Petroleum, Mexico, Government, Louisiana, Gulf of Mexico, Mississippi River, Gulf Coast of the United States, Galveston, Texas

28

This study was conducted at a centralized wastewater treatment plant that receives discharges from nearly 160 industries. The chemical oxygen demand (COD) was fractionated for two objectives: delineation of the limits of the activated sludge process being used at the plant, and evaluation of the potential environmental impact of the treated effluent. Physico-chemical analyses, respirometric and biodegradation tests, as well as COD fractionation were carried out. Molasses-wastewaters were determined to be the major contribution to the plant. The influent was dark brown in color, with a relatively high content of both organics (2503 mg/L COD) and salts (5459 μS/cm conductivity), but a low biochemical oxygen demand (568 mg/L BOD(5)) and BOD(5)/COD ratio (0.24). The degradability of the organics was limited by the high content of inert soluble COD (S(I)). The COD fractionation pattern was 40-20-40% for S(I), X(I) (inerts) and S(H) (soluble hydrolyzable), respectively. More than 90% BOD(5) removal was obtained, which was sufficient for the plant to meet the national Standards. However, the effluent discharged into the river was intensely colored and polluted (>1000 mg/L COD, >5000 μS/cm), emphasizing the need for legislation regulating COD, color and salinity, and for upgraded treatment methods worldwide for molasses wastewaters.

Concepts: Water pollution, Sewage treatment, Anaerobic digestion, Wastewater, Chemical oxygen demand, Activated sludge, Environmental engineering, Biochemical oxygen demand

28

As a result of the huge economic and environmental destruction from oil spills, studies have been directed at improving and deploying natural sorbents which are not only the least expensive but also the safest means of spill control. This research reviews the limitations and environmental impact of existing cleanup methods. It also justifies the need for concerted research effort on oil spill control using natural and sustainable technology concepts. The article proposes future guidelines for the development of a sustainable cleanup technology. Finally, guidelines for the development of a new technology for the Middle East are proposed, which is the use of an abundant resource-date palm fibers-for such techniques.

Concepts: Petroleum, Natural environment, Middle East, Asia, Environmental science, Exxon Valdez oil spill, Oil spill, Near East

28

This study explores the influence of the chemical composition (SiO(2), CaO, Fe(2)O(3), and Al(2)O(3)) of incinerator bottom ash on its friction angle. Direct shear tests were performed to measure the strength of bottom ash with two distinctly different compositions. Then, an empirical equation was regressed to determine the correlation between each composition and the friction angle. The experimental results showed that the main constituent material of the incinerator bottom ash from general municipal wastes is SiO(2), and the friction angle is 48.04°-52.66°. The bottom ash from incineration plants treating both municipal wastes and general industrial wastes has a high content of iron-aluminum oxides, and its friction angle is 44.60°-52.52°. According to the multivariate regression analysis result, the friction angle of bottom ash of any composition is influenced mainly by the Fe(2)O(3) and Al(2)O(3) contents. This study used the friction angle of the bottom ash from four different incineration plants to validate the empirical equation, and found that the error between actual friction angles and the predicted values was -1.36% to 5.34%. Therefore, the regressed empirical equation in this study can be employed in engineering applications to preliminarily identify the backfill quality of incinerator bottom ash.

Concepts: Regression analysis, Empiricism, Recycling, Incineration, Biodegradable waste, Bottom ash, Incinerator bottom ash

28

It is predicted that the coastal zone will be among the environments worst affected by projected climate change. Projected losses in beach area will negatively impact on coastal infrastructure and continued recreational use of beaches. Beach nourishment practices such as artificial nourishment, replenishment and scraping are increasingly used to combat beach erosion but the extent and scale of projects is poorly documented in large areas of the world. Through a survey of beach managers of Local Government Areas and a comprehensive search of peer reviewed and grey literature, we assessed the extent of nourishment practices in Australia. The study identified 130 beaches in Australia that were subject to nourishment practices between 2001 and 2011. Compared to projects elsewhere, most Australian projects were small in scale but frequent. Exceptions were nine bypass projects which utilised large volumes of sediment. Most artificial nourishment, replenishment and beach scraping occurred in highly urbanised areas and were most frequently initiated in spring during periods favourable to accretion and outside of the summer season of peak beach use. Projects were generally a response to extreme weather events, and utilised sand from the same coastal compartment as the site of erosion. Management was planned on a regional scale by Local Government Authorities, with little monitoring of efficacy or biological impact. As rising sea levels and growing coastal populations continue to put pressure on beaches a more integrated approach to management is required, that documents the extent of projects in a central repository, and mandates physical and biological monitoring to help ensure the engineering is sustainable and effective at meeting goals.

Concepts: Sediment, Weather, Coast, Beach, Sand, Coastal geography, Extreme weather, Beach nourishment

28

The effect of dyeing auxiliaries on UV/H(2)O(2) removal of an indigoid dye, Acid Blue 74 (AB74) from the solution was investigated. The inhibition effect of anions including carbonate, bicarbonate and chloride on the process efficiency was evaluated in terms of color removal and total organic carbon (TOC) abatement. The presence of carbonate, bicarbonate and chloride anions had no considerable effect on the total decolorization time. However, the degradation efficiency of the process was enhanced by bicarbonate anion during the first 80 min of the process. During this period, the formation of active oxygen species such as CO(3)(-),HCO(4)(-)andO(2)(-) that participate in the degradation process of AB74 increases the degradation rate, in spite of the consumption of hydroxyl radicals by these anions. After this period, the overall efficiency was considerably decreased. Adding the chloride had less decreasing effect compared to the bicarbonate. The order of anions as AB74 degradation inhibitor in this study could be concluded as: [Formula: see text] .

Concepts: Oxygen, Carbon dioxide, Acid, Hydrogen, Carbon, Oxide, Ion, Chemical formula

28

Sustainability assessments of coastal beach exploitation are difficult because the identification of appropriate monitoring methodologies and evaluation procedures is still ongoing. In particular, the most suitable procedure for the application of sustainability assessment to coastal beaches remains uncertain. This paper presents a complete sustainability assessment process for coastal beach exploitation based on the analytic hierarchy process (AHP). We developed an assessment framework consisting of 14 indicators derived from the three dimensions of suitability, economic and social value, and ecosystem. We chose a wind power project on a coastal beach of Yancheng as a case study. The results indicated that the wind power farms on the coastal beach were not completely in keeping with sustainable development theory. The construction of the wind power farms had some negative impacts. Therefore, in the design stage, wind turbines should be designed and planned carefully to minimize these negative impacts. In addition, the case study demonstrated that the AHP was capable of addressing the complexities associated with the sustainability of coastal beaches.

Concepts: Assessment, Sustainability, Analytic Hierarchy Process, Renewable energy, Wind power, Wind farm, Wind turbine, Arithmetical hierarchy

28

Water shortages and the drive to recycle is increasing interest in reuse of reclaimed wastewater. Timely and cost-effective ways to detect fecal pollutants prior to reuse increases confidence of residents and neighbors concerned about reuse of reclaimed wastewater. The on-site wastewater treatment and reuse systems (OWTRS) used in this study include a septic tank, peat bioreactor, ClO(2) disinfection and land spray irrigation system. Bacteroides fragilis, Escherichiacoli and Enterococcus spp., were tested with immunomagnetic separation/ATP bioluminescence (IMS/ATP), qPCR and culture-based methods. The results displayed a 2-log reduction in fecal bacteria in the peat bioreactor and a 5-log reduction following chloride dioxide disinfection. The fecal bacteria levels measured by IMS/ATP correlated with qPCR results: HuBac 16S (R(2) = 0.903), Bf-group 16S (R(2) = 0.956), gyrB (R(2) = 0.673), and Ent 23S (R(2) = 0.724). This is the first study in which the newly developed human-specific IMS/ATP and previously developed IMS/ATP were applied for determining OWTRS efficiency. Results of the study revealed that IMS/ATP is a timely and cost-effective way to detect fecal contaminants, and results were validated with qPCR and culture based methods. The new IMS/ATP can also be applied broadly in the detection of human-originated fecal contamination.

Concepts: Bacteria, Gut flora, Sewage treatment, Wastewater, Denitrification, Reclaimed water, Septic tank, Greywater