Greg Thoma

Invited review: Environmental impacts of dairy processing and products: A review

The objective of this review is to summarize research efforts and case studies to date of the environmental impacts from dairy processing. The pervasiveness of greenhouse gas emission, water use, consumer waste, and other environmental impacts of dairy are described. An outline of the method of choice, the life cycle assessment, for conducting research and deciding appropriate allocation of the impacts is provided. Specific research examples in dairy processing highlight how the representative final product is associated with environmental impacts to air, water, and land. The primary conclusion from the study was the usefulness of life cycle assessment methodology and the need for further research due to limited studies, variable data, and the magnitude of environmental impact.

Regional carbon footprint analysis of dairy feeds for milk production in the USA

PurposeA greenhouse gas emissions analysis (carbon footprint) was conducted for cultivation, harvesting, and production of common dairy feeds used for the production of dairy milk in the USA. The goal was to determine the carbon footprint (grams CO2 equivalents (gCO2e)/kg of dry feed) in the USA on a regional basis, identify key inputs, and make recommendations for emissions reduction.MethodsCommonly used dairy feeds in the USA, such as soybeans, alfalfa, corn, and others, were identified based on a recent literature review and information from dairy farm surveys. The following input data for the cultivation and harvesting of dairy feeds were collected for five US regions: crop production data, energy input, soil amendments, and crop protection chemicals. Life cycle inventory input data were mainly collected from the US Department of Agriculture National Agricultural Statistical Service on a state-by-state basis as well as from state extension services forage crop budget estimates. In addition to consulting other life cycle assessment studies and published articles and reports, this cradle-to-farm gate carbon footprint analysis was conducted using the Ecoinvent™ unit processes in SimaPro version 7.1© (PRé Consultants 2009).ResultsThe final carbon footprint results (gCO2e/kg of dry dairy feed) varied regionally depending on a number of factors such as lime and fertilizer application rates. The average national US carbon footprint results of the main feeds were: corn grain (390), corn silage (200), dried distillers grains with solubles (910 dry mill, 670 wet mill), oats (850), soybeans (390), soybean meal (410), winter wheat (430), alfalfa hay (170), and forage mix (160).Conclusions and recommendationsThe southeast dairy region generally showed a relatively high level of carbon footprint for most feeds, and this is attributable to the higher application rates of both synthetic fertilizers and lime. The highest contributor to carbon footprint for most regions (apart from soybeans and soybean meal) was due to the application of inorganic nitrogen fertilizer. Efficient transfer of knowledge to farmers with regards to fertilizer best management practices such as precision application of farm nutrients may contribute significantly to reducing regional crop carbon footprints.

Economic and Environmental Impact of Rice Blast Pathogen ( Magnaporthe oryzae ) Alleviation in the United States

Rice blast (Magnaporthe oryzae) is a key concern in combating global food insecurity given the disease is responsible for approximately 30% of rice production losses globally—the equivalent of feeding 60 million people. These losses increase the global rice price and reduce consumer welfare and food security. Rice is the staple crop for more than half the world’s population so any reduction in rice blast would have substantial beneficial effects on consumer livelihoods. In 2012, researchers in the US began analyzing the feasibility of creating blast-resistant rice through cisgenic breeding. Correspondingly, our study evaluates the changes in producer, consumer, and environmental welfare, if all the rice produced in the Mid-South of the US were blast resistant through a process like cisgenics, using both international trade and environmental assessment modeling. Our results show that US rice producers would gain 69.34 million dollars annually and increase the rice supply to feed an additional one million consumers globally by eliminating blast from production in the Mid-South. These results suggest that blast alleviation could be even more significant in increasing global food security given that the US is a small rice producer by global standards and likely experiences lower losses from blast than other rice-producing countries because of its ongoing investment in production technology and management. Furthermore, results from our detailed life cycle assessment (LCA) show that producing blast-resistant rice has lower environmental (fossil fuel depletion, ecotoxicity, carcinogenics, eutrophication, acidification, global warming potential, and ozone depletion) impacts per unit of rice than non-blast resistant rice production. Our findings suggest that any reduction in blast via breeding will have significantly positive impacts on reducing global food insecurity through increased supply, as well as decreased price and environmental impacts in production.

A mathematical model of phytoremediation for petroleum contaminated soil: sensitivity analysis.

Phytoremediation is an attractive treatment technology for many contaminated sites due to its cost effectiveness and public acceptance. We present a sensitivity analysis of important parameters from a screening level model for phytoremediation by grass species of weathered petroleum-contaminated sites. The conceptual framework is that root movement through contaminated soil will enhance contaminant biodegradation by providing a local environment more favorable for petroleum degrading microorganisms—the so-called rhizosphere effect. Common questions in phytoremediation are, “What species should be planted?” and “What management practices should be followed?” These choices may affect degradation kinetics, root biomass (and therefore rhizosphere volume), and the root turnover. Important model parameters are the rate constants, rhizosphere volume, and the rate of root turnover. We present a sensitivity analysis with the aim of identifying the most important factors for improving phytoremediation effectiveness. For simulations of the phytoremediation of weathered diesel range organics, our results indicate that annual species, with higher root turnover, are preferred over perennial species with the caveat of equal degradation rate constants, that is, no species-dependent effects. In addition, the results suggest that the management of nonrhizosphere soil could play an important role in the overall effectiveness of phytoremediation. Finally, the effect of increasing root biomass or increasing the rhizosphere thickness is approximately equivalent with respect to the ultimate removal of the contaminants.

A Mathematical Model of Phytoremediation for Petroleum-Contaminated Soil: Model Development

We present a simple model for root length density that combines the generally accepted spatial (exponential decrease with depth) and temporal (sinusoidal) variability of root length. Parameters in this model for root length density can be determined from assumed or measured information regarding the annual biomass turnover, maximum standing biomass, and maximum depth of root penetration. The root length density model, coupled with information regarding the average root lifespan, gives specific root growth and senescence functions that are the forcing functions for the phytoremediation model. We present a screening level mathematical model for phytoremediation that accounts for the growth and senescence of roots in the system. This is an important factor for recalcitrant, immobile compounds found in weathered crude oil contaminated soils. The phytoremediation model is based on variable volume compartments that have individual first-order degradation rate constants; as the roots move through the soil, the soil cycles through the rhizosphere zone, decaying root zone and bulk soil zone. Thus, although the oil is immobile, as the roots penetrate through the soil the oil is brought into contact with the rhizosphere.

What does Life-Cycle Assessment of agricultural products need for more meaningful inclusion of biodiversity?

Decision-makers increasingly use life-cycle assessment (LCA) as a tool to measure the environmental sustainability of products. LCA is of particular importance in globalized agricultural supply chains, which have environmental effects in multiple and spatially dispersed locations. Incorporation of impacts on biodiversity that arise from agricultural production systems into environmental assessment methods is an emerging area of work in LCA, and current approaches have limitations, including the need for (i) improved assessment of impacts to biodiversity associated with agricultural production, (ii) inclusion of new biodiversity indicators (e.g. conservation value, functional diversity, ecosystem services) and (iii) inclusion of previously unaccounted modelling variables that go beyond land-use impacts (e.g. climate change, water and soil quality). Synthesis and applications. Ecological models and understanding can contribute to address the limitations of current life-cycle assessment (LCA) methods in agricultural production systems and to make them more ecologically relevant. This will be necessary to ensure that biodiversity is not neglected in decision-making that relies on LCA.

Integration of Water Resource Models with Fayetteville Shale Decision Support and Information System

Significant issues can arise with the timing, location, and volume of surface water withdrawals associated with hydraulic fracturing of gas shale reservoirs as impacted watersheds may be sensitive, especially in drought years, during low flow periods, or during periods of the year when activities such as irrigation place additional demands on the surface supply of water. Significant energy production and associated water withdrawals may have a cumulative impact to watersheds over the short-term. Hence, hydraulic fracturing based on water withdrawal could potentially create shifts in the timing and magnitude of low or high flow events or change the magnitude of river flow at daily, monthly, seasonal, or yearly time scales. These changes in flow regimes can result in dramatically altered river systems. Currently little is known about the impact of fracturing on stream flow behavior. Within this context the objective of this study is to assess the impact of the hydraulic fracturing on the water balance of the Fayetteville Shale play area and examine the potential impacts of hydraulic fracturing on river flow regime at subbasin scale. This project addressed that need with four unique but integrated research and development efforts: 1) Evaluate the predictive reliability of the Soil and Water Assessment Tool (SWAT) model based at a variety of scales (Task/Section 3.5). The Soil and Water Assessment Tool (SWAT) model was used to simulate the across-scale water balance and the respective impact of hydraulic fracturing. A second hypothetical scenario was designed to assess the current and future impacts of water withdrawals for hydraulic fracturing on the flow regime and on the environmental flow components (EFCs) of the river. The shifting of these components, which present critical elements to water supply and water quality, could influence the ecological dynamics of river systems. For this purpose, we combined the use of SWAT model and Richter et al.’s (1996) methodology to assess the shifting and alteration of the flow regime within the river and streams of the study area. 2) Evaluate the effect of measurable land use changes related to gas development (well-pad placement, access road completion, etc.) on surface water flow in the region (Task/Section 3.7). Results showed that since the upsurge in shale-gas related activities in the Fayetteville Shale Play (between 2006 and 2010), shale-gas related infrastructure in the region have increase by 78%. This change in land-cover in comparison with other land-cover classes such as forest, urban, pasture, agricultural and water indicates the highest rate of change in any land-cover category for the study period. A Soil and Water Assessment Tool (SWAT) flow model of the Little Red River watershed simulated from 2000 to 2009 showed a 10% increase in storm water runoff. A forecast scenario based on the assumption that 2010 land-cover does not see any significant change over the forecast period (2010 to 2020) also showed a 10% increase in storm water runoff. Further analyses showed that this change in the stream-flow regime for the forecast period is attributable to the increase in land-cover as introduced by the shale-gas infrastructure. 3) Upgrade the Fayetteville Shale Information System to include information on watershed status. (Tasks/Sections 2.1 and 2.2). This development occurred early in the project period, and technological improvements in web-map API’s have made it possible to further improve the map. The current sites (http://lingo.cast.uark.edu) is available but is currently being upgraded to a more modern interface and robust mapping engine using funds outside this project. 4) Incorporate the methodologies developed in Tasks/Sections 3.5 and 3.7 into a Spatial Decision Support System for use by regulatory agencies and producers in the play. The resulting system is available at http://fayshale.cast.uark.edu and is under review the Arkansas Natural Resources Commission.

Monitoring Soil Ecosystem Recovery Following Bioremediation of a Terrestrial Crude Oil Spill With and Without a Fertilizer Amendment

The effect of fertilizer as an amendment in the bioremediation of a terrestrial crude oil spill has been investigated in terms of the subsequent recovery of the soil ecosystem following bioremediation. Two different spills in the same area with different initial hydrocarbon concentrations (33,500 mg kg-1 and 4,800 mg kg-1) were compared. At the higher initial hydrocarbon concentration fertilizer addition increased the rate of bioremediation (first-order rate constant of 0.0033 days-1 with fertilizer amendment vs. 0.0020 days-1 without) and resulted in more rapid recovery of soil bacteria (numbers, community structure, diversity) and nematodes (trophic diversity and community structure). The effect of the fertilizer amendment was more significant at the higher initial concentration of crude oil hydrocarbons, presumably due to greater depletion of soil nutrient pools in the absence of the amendment. A second objective of this work was to identify sensitive and cost-effective ecological indicators useful for monitoring the recovery of soil ecosystems impacted by crude oil. Ecological indicators used included: microbial numbers, community structure, and activity as revealed by biomarker analysis (phospholipid fatty acids); nitrogen availability; nematode numbers and community structure (trophic groups and colonizer-persister classes); and ultimately, plant cover and diversity. All ecological indicators investigated were sensitive to disturbances in the soil food web in a hydrocarbon-impacted site. However, nematode community structure analysis offered the greatest sensitivity coupled with low cost and readily available sources for the analysis.

Environmental Sustainability of Fluid Milk Delivery Systems in the United States

Beverage producers in the United States choose packaging based on cost and consumer preference. Monolayer high†density polyethylene (HDPE) and gable†top carton containers have long dominated the U.S. fluid milk market, but pressure for more sustainable packaging is increasing. We present a broad discussion on environmental sustainability of 18 fluid milk containers through life cycle assessment. Because different container types require unique milk processing, distribution, and disposal and incur or avoid milk losses, fluid milk delivery systems (FMDSs) are evaluated, rather than containers in isolation. By assessing FMDSs, a complete measure of containers’ environmental sustainability was obtained. Despite conservative assumptions about milk losses, differences in container size, milk processing, distribution, and container recycling, pair†wise cradle†to†grave comparisons of FMDSs show there are no superior FMDSs. But, 500†to 1,000†milliliter FMDSs are potentially superior to ≥half gallon if they prevent milk losses. Thus, the future of FMDSs in the United States depends on the industrys ability to prevent distribution (12%) and consumption milk losses (20% to 35%). Farm†gate†to†grave comparisons showed that chilled HDPE FMDSs are superior to other plastic and chilled paperboard FMDSs for climate†change impact, but the result is inconclusive for chilled HDPE to ambient (unrefrigerated) paperboard or plastic pouch FMDS comparisons. Plastic pouch FMDSs show potential to reduce nonrenewable fossil energy, but need to be recyclable. Ambient FMDSs are superior to chilled FMDSs for water depletion. Eight†ounce paperboard FMDSs are superior to 8†ounce plastic FMDSs. Thus, alternative FMDSs may improve environmental sustainability of the U.S. postfarm fluid milk supply chain.

Nematodes as Bioindicators of Ecosystem Recovery During Phytoremediation of Crude Oil Contaminated Soil

Restoration of a weathered crude oil contaminated site undergoing phytoremediation was evaluated using nematodes as bioindicators. Samples were collected twice per year equating to spring and fall/winter. Mean annual total abundances ranged from 18–130 in the non-fertilized non-vegetated control (CTR) to 69–728 in tall fescue-ryegrass (FES) to 147–749 (100 g−1) in the fertilized bermudagrass-fescue (BER) treatment. Proportions of plant-parasitic (PP) and free-living (FL) nematodes were significantly impacted by treatment, but not year, with PP nematodes accounting for 27, 59, and 68% of CTR, FES, and BER communities, respectively. There was no significant year by season by treatment or treatment by year effect for total, PP, or FL nematode abundances. Diversity did not increase over time. The BER and FES treatments had more mature communities as indicated by higher plant-parasitic index (PPI) values. Phytoremediation accelerates petroleum degradation and alters the soil habitat which is reflected in the nematode community. However, low numbers and inconsistent presence of persister strategist omnivores and predators, and the lack in improvement over time in treatment effects for total and PP nematode abundances, PP and FL proportions, or PPI indicate the system is being rehabilitated but has not been restored after 69 months of phytoremediation.