Green Leaf Volatiles in the Atmosphere—Properties, Transformation, and Significance

This review thoroughly covers the research on green leaf volatiles (GLV) in the context of atmospheric chemistry. It briefly takes on the GLV sources, in-plant synthesis, and emission inventory data. The discussion of properties includes GLV solubility in aqueous systems, Henry’s constants, partition coefficients, and UV spectra. The mechanisms of gas-phase reactions of GLV with OH, NO3, and Cl radicals, and O3 are explained and accompanied by a catalog of products identified experimentally. The rate constants of gas-phase reactions are collected in tables with brief descriptions of corresponding experiments. A similar presentation covers the aqueous-phase reactions of GLV. The review of multiphase and heterogeneous transformations of GLV covers the smog-chamber experiments, products identified therein, along with their yields and the yields of secondary organic aerosols (SOA) formed, if any. The components of ambient SOA linked to GLV are briefly presented. This review recognized GLV as atmospheric trace compounds that reside primarily in the gas phase but did not exclude their transformation in atmospheric waters. GLV have a proven potential to be a source of SOA with a global burden of 0.6 to 1 Tg yr−1 (estimated jointly for (Z)-hexen-1-ol, (Z)-3-hexenal, and 2-methyl-3-buten-2-ol), 0.03 Tg yr−1 from switch grass cultivation for biofuels, and 0.05 Tg yr−1 from grass mowing.

Designing a sustainable biofuel supply chain by considering carbon policies: a case study in Iran

Background Carbon emissions and global warming have increased as a result of population growth and greater usage of fossil fuels. Finding a long-term replacement for fossil fuels, such as biofuels, has become a major problem for energy supply management in recent years. Sustainability must be addressed as a key problem in building biofuel supply chains (BSCs), given the pressing need for societies to limit environmental consequences and promote social responsibility of company activities. Various modeling frameworks have been established so far to design a BSC. At the same time, no research exists that examines both the sustainable development paradigm and the influence of various carbon regulatory policies on the strategic and operational decisions made by BSCs. Methods This study develops a multi-objective, multi-period, multi-echelon BSC from switch grass regarding the economic, environmental and social aspects of sustainability. Four carbon policies are taken into account when assessing the environmental aspect: the carbon cap, the carbon tax, the carbon trade, and the carbon offset. To solve the multi-objective model, the fuzzy interactive programming method is used, and the fuzzy best–worst method is used to weight the social objective components. Results An actual case study in Iran is studied to demonstrate the model’s applicability. Under various carbon policies, different network configurations are obtained based on the location of switch grass resources and installed facilities. Biofuel production and transportation activities account for approximately 28% and 51% of total carbon emissions, respectively, according to numerical results. Furthermore, these activities account for roughly 62% of overall expenses. In the suggested case study, implementing the carbon trade policy reduces carbon emissions by more than 30% while increasing total profit by about 27%. In comparison to other policies, the carbon trade policy has a substantial impact on enhancing social considerations. Overall, the carbon trade policy can greatly improve the economic and environmental components of sustainability without significantly decreasing in the social sustainability. Conclusions The proposed model can assist policymakers and governments in simultaneously optimizing BSC profitability, carbon emission reduction, and social concern.

Bipolaris victoriae (Victoria blight of oats).

A disease almost unknown prior to 1944 (Romanko, 1957), Bipolaris victoriae is a potentially destructive disease of oats (it reduced the Iowa oat crop by 32% in 1947) (Anon, 1965) that currently has a limited host range and geographical spread. It has been reported from several continents and associated with several crops, however its status as a pathogen on crops could be questioned in all cases with the exception of oats, timothy grass and switch grass. It is seedborne and thus any trade in seed both for cultivation or for livestock feed is a potential means of spread. The virulence of the fungus is due to the production of a peptide often called a host-specific toxin 'victorin'. The disease has generally been controlled through the use of genetically resistant lines but the resistance gene which confers resistance to victorin actually causes plants to become susceptible to crown rust, caused by Puccinia coronata (Lorang et al., 2007).

Soil depth gradients in microbial growth kinetics under deeply- vs. shallow-rooted plants

Climate-smart land management practices that replace shallow-rooted annual crop systems with deeply-rooted perennial plants can contribute to soil carbon sequestration. However, deep soil carbon accrual may be influenced by active microbial biomass and their capacity to assimilate fresh carbon at depth. Incorporating active microbial biomass, dormancy and growth in models can improve our ability to predict the capacity of soil to store carbon. But, so far, the microbial parameters that are needed for such modeling are poorly constrained, especially in deep soil layers. Here, we investigated whether a change in crop rooting depth affects microbial growth kinetics in deep soils compared to surface soils. We used a lab incubation experiment and growth kinetics model to estimate how microbial parameters vary along 240 cm of soil depth in profiles under shallow- (soy) and deeply-rooted plants (switch grass) 11 years after plant cover conversion. We also assessed resource origin and availability (total organic carbon, 14C, dissolved organic carbon, specific UV absorbance, total nitrogen, total dissolved nitrogen) along the soil profiles to examine associations between soil chemical and biological parameters. Even though root biomass was higher and rooting depth was deeper under switch grass than soy, resource availability and microbial growth parameters were generally similar between vegetation types. Instead, depth significantly influenced soil chemical and biological parameters. For example, resource availability, and total and relative active microbial biomass decreased with soil depth. Decreases in the relative active microbial biomass coincided with increased lag time (response time to external carbon inputs) along the soil profiles. Even at a depth of 210-240 cm, microbial communities were activated to grow by added resources within a day. Maximum specific growth rate decreased to a depth of 90 cm and then remained consistent in deeper layers. Our findings show that > 10 years of vegetation and rooting depth changes may not be long enough to alter microbial growth parameters, and suggest that at least a portion of the microbial community in deep soils can grow rapidly in response to added resources. Our study determined microbial growth parameters that can be used in models to simulate carbon dynamics in deep soil layers.

Bipolaris victoriae (Victoria blight of oats).

A disease almost unknown prior to 1944 (Romanko, 1957), Bipolaris victoriae is a potentially destructive disease of oats (it reduced the Iowa oat crop by 32% in 1947) (Anon, 1965) that currently has a limited host range and geographical spread. It has been reported from several continents and associated with several crops, however its status as a pathogen on crops could be questioned in all cases with the exception of oats, timothy grass and switch grass. It is seedborne and thus any trade in seed both for cultivation or for livestock feed is a potential means of spread. The virulence of the fungus is due to the production of a peptide often called a host-specific toxin 'victorin'. The disease has generally been controlled through the use of genetically resistant lines but the resistance gene which confers resistance to victorin actually causes plants to become susceptible to crown rust, caused by Puccinia coronata (Lorang et al., 2007).

Designing a Sustainable Biofuel Supply Chain by Considering Carbon Policies: A Case Study in Iran

Background: Population growth and increasing the utilization of fossil fuels have increased carbon emissions and the global warming phenomenon with detrimental impacts on the human life and the environment. Therefore, finding a sustainable substitution for fossil fuels becomes a great challenge for all societies from all over the world. Renewable energies such as biofuels are the appropriate alternative to decrease environmental concerns.Methods: This study develops a multi-objective multi-period multi-echelon biofuel supply chain (BSC) from switch grass regarding economic, environmental and social aspects of the sustainability. For considering the environmental aspect, four carbon policies are taken into account; namely the carbon cap, the carbon tax, the carbon trade and the carbon offset. The fuzzy interactive programming method is implemented to solve the multi-objective model and the fuzzy best-worst method (FMWM) is applied for weighting social objective components.Results: To illustrate the applicability of the model, an actual case study in Iran is considered. It is revealed that different solutions are obtained for the location of switch grass resources, preprocessing centers, and bio-refineries under different carbon policies. Numerical results also demonstrate that biofuel production and transportation activities have a great share in carbon emissions and BSC costs. Applying the carbon cap policy in the proposed case study decreases the carbon emission over 14% in comparison to the basic situation. Moreover, implementing the carbon trade policy increases the total BSC profit about 11% in comparison to the basic situation. The carbon offset policy plays a significant role in improving social considerations compared with other policies. Overall, since three aspects of sustainability have appropriate values under the carbon trade policy, it can be concluded that this policy is the most appropriate policy.Conclusions: The proposed model can aid policy makers and governments to optimize the profitability of the BSC, the carbon emission reduction, and the social consideration, simultaneously.

Evaluation of the Influence of Individual Clay Minerals on Biochar Carbon Mineralization in Soils

Although association between mineral and biochar carbon have been speculated in some studies, still there is no direct evidence for the influence of individual clay minerals on the mineralization of biochar carbon in soils. To address this, we conducted an incubation study using monomineralic soils constituted by separately mixing pure minerals, i.e., smectite, kaolinite, and goethite, with a sandy soil. Switch grass biochar (400 °C) was added to the artificial soils and samples were incubated for 90 days at 20 °C in the laboratory. The CO2-C mineralized from the control, and biochar amended soil was captured in NaOH traps and the proportion of C mineralized from biochar was determined using δ13C isotopic analysis. The clay minerals significantly decreased the cumulative total carbon mineralized during the incubation period, whereas biochar had no effect on this. The least amount of total C was mineralized in the presence of goethite and biochar amended soil, where only 0.6% of the native soil organic carbon (SOC) (compared to 4.14% in control) and 2.9% of the biochar-C was mineralized during the 90 days incubation period. Native SOC mineralization was significantly reduced in the presence of biochar and the three minerals. Goethite was most effective in stabilizing both biochar and the native soil organic carbon. The short-term data from this study demonstrate that biochar application in Fe oxide rich soils may be an effective strategy to sequester biochar carbon, as well as to stabilize native soil carbon.