Soil-plant nitrogen isotope composition and nitrogen cycling after biochar applications

Environmental Science and Pollution Research - Biochar has strong potential to improve nitrogen (N) use efficiency in both agricultural and horticultural systems. Biochar is usually co-applied with...     

Soil carbon and nitrogen dynamics in the first year following herbicide and scalping in a revegetation trial in south-east Queensland,Australia

During revegetation, the maintenance of soil carbon (C) pools and nitrogen (N) availability is considered essential for soil fertility and this study aimed to evaluate contrasting methods of site preparation (herbicide and scalping) with respect to the effects on soil organic matter (SOM) during the critical early establishment phase. Soil total C (TC), total N (TN), hot-water extractable organic C (HWEOC), hot-water extractable total N (HWETN), microbial biomass C and N (MBC and MBN), total inorganic N (TIN) and potentially mineralizable N (PMN) were measured over 53 weeks. MBC and MBN were the only variables affected by herbicide application. Scalping caused an immediate reduction in all variables, and the values remained low without any sign of recovery for the period of the study. The impact of scalping on HWETN and TIN lasted 22 weeks and stabilised afterwards. MBC and MBN were affected by both herbicide and scalping after initial treatment application and remained lower than control during the period of the study but did not decrease over time. While scalping had an inevitable impact on all soil properties that were measured, that impact did not worsen over time, and actually improved plant growth (unpublished data) while reducing site establishment costs. Therefore, it provides a useful alternative for weed control in revegetation projects where it is applied only once at site establishment and where SOM would be expected to recover as canopy closure is obtained and nutrient cycling through litterfall commences.     

Comparison of refrigerated warehouse energy demand with R-717 and R-507 using eQUEST model

Natural refrigerant ammonia R-717 and synthetic azeotropic refrigerant R-507 (a blend containing 50% R-143a and 5% R-125 by weight) are used in a wide range of refrigeration systems especially in low-temperature applications. R-717 and R-507 are ozone friendly refrigerants, which have no Ozone Depletion Potential (ODP). Global Warming Potential (GWP) of R-717 and R-507 is equal to zero and 3300, respectively. The high amount of R-507 GWP demonstrates its negative effect on the Earth’s climate change. In this study, a refrigerated warehouse located in Cincinnati, Ohio was modeled and the total energy demand and Coefficient of Performance (COP) was evaluated by eQUEST using two scenarios. The R-717 and R-507 were used as refrigerant in the first and second scenarios, respectively. The results showed that using R-717 in the refrigeration system leads to a 15% energy saving and a higher COP compared to R-507 in all working conditions. The only exception is that at an evaporating temperature below ?35°C which COP values of both refrigerants are approximately equal.     

Simple Modeling Tool for Reconstructing Source History Using High Resolution Contaminant Profiles From Low‐k Zones

An innovative but simple analytical modeling tool for reconstructing contaminant concentration versus time trends (i.e., “source history”) for a site using high‐resolution contaminant profiles from low permeability (low‐k) zones was developed and tested. Migration of contaminants into low‐k zones via diffusion (and possibly slow advection) produce concentration versus depth profiles that can be used to understand temporal concentration trends at the interface with overlying transmissive zones, including evidence of attenuation over time due to source decay. A simple transport‐based spreadsheet tool for generating source history estimates fit to the profiles was developed and applied to published soil concentration versus depth data from five distinct areas of four different sites contaminated with chlorinated ethenes. Using the root mean square error as an optimization metric, strong fits between measured and model‐predicted soil data were obtained in the majority of cases using site‐specific values for input parameters. In general, significant improvements could not be obtained by varying these parameters. As a result, the source history estimates generated by the tool were similar to those that had already been generated using more intensive analytical or numerical inverse modeling approaches. This included confirmation of constant source histories at locations where dense nonaqueous‐phase liquid was present (or suspected to be present), and declining source histories for locations where source isolation and/or attenuation had occurred. The advantage of the modeling tool described here is that it provides a simpler yet more dynamic method for understanding source behavior over time than existing approaches. ©2015 Wiley Periodicals, Inc.     

Experimental study of rubber tire aggregates effect on compressive and dynamic load-bearing properties of cylindrical concrete specimens

Sustainable development has become a major focus for engineers and planners as part of their collective efforts in finding, developing and integrating environmental-friendly solutions for material recycling and waste management into design and construction of civil engineering infrastructure. In the past three decades, there has been an increase in recycling and application of waste materials into the concrete to decrease costs and improve material properties of the concrete. Significant growth in automobile manufacturing industry and increased rubber tire supply for vehicles suggested the application of waste tire particles as concrete aggregates to minimize the ecological footprint of the rubber tire waste due to its recycling process difficulties. In this paper, the effect of rubber tire particles on compressive and dynamic strength of concrete specimens with different particle percentiles was tested on more than 55 cylindrical specimens. To achieve the optimal mix design properties of rubber tire concrete specimens, both fine and coarse aggregates got replaced by fine and coarse rubber particles. Introduction of rubber tire particles as coarse and fine aggregate reduces the brittleness of the concrete and provides more flexible aggregate bonding which ultimately improves the dynamic resistance of the concrete. It increases the concrete workability and provides environmental-friendly and cost-effective solutions in using recycled materials for concrete construction applications.     

Water pinch analysis for water and wastewater minimization in Tehran oil refinery considering three contaminants

This study aims to find an appropriate way to minimize water utility in the petrochemical and petroleum industries due to high rate of water consumption. For this purpose, Tehran oil refinery has been well studied. In this research, three key contaminants including suspended solid, hardness as well as COD have been considered to analyze the water network. In addition, the potential of water reuse was studied for all methods. These key contaminants once were analyzed separately as a single contaminant and the amount of required freshwater was calculated for them. In this stage, amount of freshwater was reduced to about 60.9 (17%), 203 (59.7%) and 143 m³/h (42.5%) in terms of suspended solids, hardness, and COD, respectively. Water minimization within operations for suspended solids is less than two others. Therefore, this is a limiting contaminant and can be selected as a key contaminant. In the next stage, three contaminants were analyzed two by two based on their mass transfer. Results show that, in the targeting for minimization based on the suspended solids and hardness, the amount of required water is reduced to 142.74 m³/h or 42%. This amount for suspended solids and COD is equal to 86.3 m³/h (26%) and for COD and hardness is 124 m³/h (37%). Analyzing the methods shows that the method based on the double contaminant gives more precise results rather than single contaminant.     

Glyphosate: environmental contamination,toxicity and potential risks to human health via food contamination

Glyphosate has been the most widely used herbicide during the past three decades. The US Environmental Protection Agency (EPA) classifies glyphosate as ‘practically non-toxic and not an irritant’ under the acute toxicity classification system. This classification is based primarily on toxicity data and due to its unique mode of action via a biochemical pathway that only exists in a small number of organisms that utilise the shikimic acid pathway to produce amino acids, most of which are green plants. This classification is supported by the majority of scientific literature on the toxic effects of glyphosate. However, in 2005, the Food and Agriculture Organisation (FAO) reported that glyphosate and its major metabolite, aminomethylphosphonic acid (AMPA), are of potential toxicological concern, mainly as a result of accumulation of residues in the food chain. The FAO further states that the dietary risk of glyphosate and AMPA is unlikely if the maximum daily intake of 1 mg kg^?1 body weight (bw) is not exceeded. Research has now established that glyphosate can persist in the environment, and therefore, assessments of the health risks associated with glyphosate are more complicated than suggested by acute toxicity data that relate primarily to accidental high-rate exposure. We have used recent literature to assess the possible risks associated with the presence of glyphosate residues in food and the environment.     

An integrated multi criteria approach for landfill siting in a conflicting environmental, economical and socio-cultural area

Landfill site selection is a complicated multi criteria land use planning that should convince all related stakeholders with different insights. This paper addresses an integrating approach for landfill siting based on conflicting opinions among environmental, economical and socio-cultural expertise. In order to gain optimized siting decision, the issue was investigated in different viewpoints. At first step based on opinion sampling and questionnaire results of 35 experts familiar with local situations, the national environmental legislations and international practices, 13 constraints and 15 factors were built in hierarchical structure. Factors divided into three environmental, economical and socio-cultural groups. In the next step, the GIS-database was developed based on the designated criteria. In the third stage, the criteria standardization and criteria weighting were accomplished. The relative importance weights of criteria and subcriteria were estimated, respectively, using analytical hierarchy process and rank ordering methods based on different experts opinions. Thereafter, by using simple additive weighting method, the suitability maps for landfill siting in Marvdasht, Iran, was evaluated in environmental, economical and socio-cultural visions. The importance of each group of criteria in its own vision was assigned to be higher than two other groups. In the fourth stage, the final suitability map was obtained after crossing three resulted maps in different visions and reported in five suitability classes for landfill construction. This map indicated that almost 1224 ha of the study area can be considered as best suitable class for landfill siting considering all visions. In the last stage, a comprehensive field visit was performed to verify the selected site obtained from the proposed model. This field inspection has confirmed the proposed integrating approach for the landfill siting.     

Study of Thermal Decomposition Kinetics of Palm Oleic Acid-Based Alkyds and Effect of Oil Length on Thermal Stability

Thermal decomposition kinetics of three palm oleic acid-based alkyds with different oil lengths and having different molecular weights were studied using TGA measurements under non-isothermal conditions. Activation energies were obtained from Kissinger and Ozawa, Flynn and Wall (OFW) methods and subsequently the pre-exponential factor, A, degradation rate constant, k, for all the alkyds were also determined. From kinetic analysis of the thermal decomposition using the OFW method, it was found that degradation of all the alkyds has taken place in more than two stages, corresponding to different mechanisms. As shown from Ozawa and Kissinger methods, the chemical composition of the alkyds influenced the thermal degradation; increasing the phthalic anhydride and glycerol, and decreasing the oleic acid increased the thermal stabilities of the alkyds.