Remote sensing technology and land use analysis in food security assessment

ABSTRACT

Climate change and a rapidly growing human population have put ever greater strains on the global food system. Although the number of food insecure people in the world has reached a record low, changing land use and climate variability will threaten our ability to maintain this progress. Profound changes in the structure of economies around the world have affected agricultural production and how food is delivered to the consumer. This paper explores connections between land use, environmental change and food availability, access, and utilization. Each of these elements of food security has vulnerabilities to changing environmental conditions and land use that can be explored using satellite remote sensing observations. Technology is a key way environmental changes can be quantified and used in food security assessment.     

Modeling heterogeneous ClNO2 formation,chloride availability,and chlorine cycling in Southeast Texas

Nitryl Chloride (ClNO₂) mixing ratios above 1 ppbv have been measured off the coast of Southeast Texas. ClNO₂ formation, the result of heterogeneous N₂O₅ uptake on chloride-containing aerosols, has a significant impact on oxidant formation for the Houston area. This work reports on the modeling of ClNO₂ formation and describes the sensitivity of ClNO₂ formation to key parameters. Model sensitivity analyses found that: (1) Chloride availability limits the formation of nitryl chloride at ground level but not aloft; (2) When excess particulate chloride was assumed to be present at ground level through sea salt, ClNO₂ concentrations increased in some locations by a factor of 13, as compared to cases where sea salt chloride was assumed to be limited; (3) Inland formation of ClNO₂ seems feasible based on chloride availability and could have a large impact on total ClNO₂ formed in the region; and (4) ClNO₂ formation is quite sensitive to the assumed yield of ClNO₂ from N₂O₅ uptake. These results demonstrate that there is a need for further field studies to better understand the geographic extent of ClNO₂ formation and the atmospheric conditions which control partitioning of chloride into the particle phase. In addition, this work examined the role of ClNO₂ in the cycling of chlorine between chloride and reactive chlorine radicals. The modeling indicated that the majority of reactive chlorine in Texas along the Gulf coast is cycled through ClNO₂, demonstrating the importance of including ClNO₂ into photochemical models for this region.     

Assessment of the reproductive capacity of <Emphasis Type="Italic">Pinus sylvestris</Emphasis> trees growing under conditions of chronic exposure to radionuclides of uranium and thorium series

The reproductive capacity of Scots pine (Pinus sylvestris L.) has been estimated in trees from the population growing in an area used to store tailings from uranium ore processing and radium production. Under such conditions, 12- to 15-year-old trees produce seeds of a quality inferior to that in areas with a normal background radiation level. As the weighted absorbed dose rate (at a weighting coefficient of 5) for generative organs increases from 0.002 ± 0.0003 to 0.344 ± 0.059 mGy/day, a proportional increase is observed in the proportion of empty seeds and the frequency of cytogenetic disturbances in the root meristem of seedlings, while the survival rate of seedlings decreases. The minimum absorbed dose rate leading to these changes in the pine population is 0.027 mGy/day, i.e., 12 times as high as the control value.     

Development of an energy discriminate CR-39(®) nuclear track etch dosimeter for Radon-220 gas measurements

An energy discriminate CR-39^® nuclear track etch dosimeter for use in a ²²⁰Rn and ²²²Rn gas monitor has been developed and experimentally assessed. It utilises a thin film of Mylar^® C to attenuate the alpha particle energies to allow only the damage tracks created by the 8.785 MeV alpha particles emitted from ²¹²Po of the ²³²Th decay chain to be registered in the CR-39^® plaque, allowing for the direct measurement of ²²⁰Rn gas concentrations. The dosimeter was developed through a combination of experimental investigations and theoretical simulations using the Monte Carlo ion transport modelling program Stopping and Range of Ions in Materials (SRIM 2008). A film thickness of 54 μm has been shown to attenuate all alpha energies less then 7.7 MeV.     

Role of back diffusion and biodegradation reactions in sustaining an MTBE/TBA plume in alluvial media

A methyl tert-butyl ether (MTBE) / tert-butyl alcohol (TBA) plume originating from a gasoline spill in late 1994 at Vandenberg Air Force Base (VAFB) persisted for over 15 years within 200 feet of the original spill source. The plume persisted until 2010 despite excavation of the tanks and piping within months after the spill and excavations of additional contaminated sediments from the source area in 2007 and 2008. The probable history of MTBE concentrations along the plume centerline at its source was estimated using a wide variety of available information, including published details about the original spill, excavations and monitoring by VAFB consultants, and our own research data. Two-dimensional reactive transport simulations of MTBE along the plume centerline were conducted for a 20-year period following the spill. These analyses suggest that MTBE diffused from the thin anaerobic aquifer into the adjacent anaerobic silts and transformed to TBA in both aquifer and silt layers. The model reproduces the observation that after 2004 TBA was the dominant solute, diffusing back out of the silts into the aquifer and sustaining plume concentrations much longer than would have been the case in the absence of such diffusive exchange. Simulations also suggest that aerobic degradation of MTBE or TBA at the water table in the overlying silt layer significantly affected concentrations of MTBE and TBA by limiting the chemical mass available for back diffusion to the aquifer.     

The impact of EDTA on lead distribution and speciation in the accumulator Sedum alfredii by synchrotron X-ray investigation

The in vivo localization and speciation of lead (Pb) in tissues of the accumulator Sedum alfredii grown in EDTA-Pb and Pb(NO₃)₂ was studied by synchrotron X-ray investigation. The presence of EDTA-Pb in solution resulted in a significant reduction of Pb accumulation in S. alfredii. Lead was preferentially localized in the vascular bundles regardless of treatments but the intensities of Pb were lower in the plants treated with EDTA. Lead was predominantly presented as a Pb-cell wall complex in the plants regardless of its supply form. However, a relatively high proportion of Pb was observed as Pb-EDTA complex when the plant was treated with EDTA-Pb, but as a mixture of Pb₃(PO₄)₂, Pb-malic, and Pb-GSH when cultured with ionic Pb. These results suggest that EDTA does not increase the internal mobility of Pb, although the soluble Pb-EDTA complex could be transported and accumulated within the plants of S. alfredii.     

The internal microstructure and fibrous mineralogy of fly ash from coal-burning power stations

Coal fly ash (CFA) is a significant environmental pollutant that presents a respiratory hazard when airborne. Although previous studies have identified the mineral components of CFA, there is a paucity of information on the structural habits of these minerals. Samples from UK, Polish and Chinese power stations were studied to further our understanding of the factors that affect CFA geochemistry and mineralogy. ICP-MS, FE-SEM/EDX, XRD, and laser diffraction were used to study physicochemical characteristics. Analysis revealed important differences in the elemental compositions and particle size distributions of samples between sites. Microscopy of HF acid-etched CFA revealed the mullite present possesses a fibrous habit; fibres ranged in length between 1 and 10 μm. Respirable particles (<10 μm) were frequently observed to contain fibrous mullite. We propose that the biopersistence of these refractory fibres in the lung environment could be contributing towards chronic lung diseases seen in communities and individuals continually exposed to high levels of CFA.     

Temporal variability in dynamic and colloidal metal fractions determined by high resolution in situ measurements in a UK estuary

In recent environmental legislation, such as the Water Framework Directive in the European Union (WFD, 2000/60/EC), the importance of metal speciation and biological availability is acknowledged, although analytical challenges remain. In this study, the Voltammetric In situ Profiler (VIP) was used for high temporal resolution in situ metal speciation measurements in estuarine waters. This instrument simultaneously determines Cd, Cu and Pb species within a size range (ca. <4 nm) that is highly relevant for uptake by organisms. The colloidal metal fraction can be quantified through a combination of VIP measurements and analyses of total dissolved metal concentrations.VIP systems were deployed over tidal cycles in a seasonal study of metal speciation in the Fal Estuary, southwest England. Total dissolved concentrations were 4.97-315 nM Cu, 0.13-8.53 nM Cd and 0.35-5.75 nM Pb. High proportions of Pb (77 ± 17%) and Cu (60 ± 25%) were present as colloids, which constituted a less important fraction for Cd (37 ± 30%). The study elucidated variations in the potentially toxic metal fraction related to river flow, complexation by organic ligands and exchanges between dissolved and colloidal phases and the sediment. Based on published toxicity data, the bioavailable Cu concentrations (1.7-190 nM) in this estuary are likely to severely compromise the ecosystem structure and functioning with respect to species diversity and recruitment of juveniles. The study illustrates the importance of in situ speciation studies at high resolution in pursuit of a better understanding of metal (bio)geochemistry in dynamic coastal systems.     

Greenhouse gas balance for composting operations

The greenhouse gas (GHG) impact of composting a range of potential feedstocks was evaluated through a review of the existing literature with a focus on methane (CH(4)) avoidance by composting and GHG emissions during composting. The primary carbon credits associated with composting are through CH(4) avoidance when feedstocks are composted instead of landfilled (municipal solid waste and biosolids) or lagooned (animal manures). Methane generation potential is given based on total volatile solids, expected volatile solids destruction, and CH(4) generation from lab and field incubations. For example, a facility that composts an equal mixture of manure, newsprint, and food waste could conserve the equivalent of 3.1 Mg CO(2) per 1 dry Mg of feedstocks composted if feedstocks were diverted from anaerobic storage lagoons and landfills with no gas collection mechanisms. The composting process is a source of GHG emissions from the use of electricity and fossil fuels and through GHG emissions during composting. Greenhouse gas emissions during composting are highest for high-nitrogen materials with high moisture contents. These debits are minimal in comparison to avoidance credits and can be further minimized through the use of higher carbon:nitrogen feedstock mixtures and lower-moisture-content mixtures. Compost end use has the potential to generate carbon credits through avoidance and sequestration of carbon; however, these are highly project specific and need to be quantified on an individual project basis.