Food waste has major consequences for social, nutritional, economic, and environmental issues, and yet the amount of food waste disposed in the U.S. has not been accurately quantified. We introduce the transparent and repeatable methods of meta-analysis and systematic reviewing to determine how much food is discarded in the U.S., and to determine if specific factors drive increased disposal. The aggregate proportion of food waste in U.S. municipal solid waste from 1995 to 2013 was found to be 0.147 (95% CI 0.137-0.157) of total disposed waste, which is lower than that estimated by U.S. Environmental Protection Agency for the same period (0.176). The proportion of food waste increased significantly with time, with the western U.S. region having consistently and significantly higher proportions of food waste than other regions. There were no significant differences in food waste between rural and urban samples, or between commercial/institutional and residential samples. The aggregate disposal rate for food waste was 0.615 pounds (0.279 kg) (95% CI 0.565-0.664) of food waste disposed per person per day, which equates to over 35.5 million tons (32.2 million tonnes) of food waste disposed annually in the U.S.
The primary objective of waste management technologies and policies in the United States is to reduce the harmful environmental impacts of waste, particularly those relating to energy consumption and climate change. Performance indicators are frequently used to evaluate the environmental quality of municipal waste systems, as well as to compare and rank programs relative to each other in terms of environmental performance. However, there currently is no consensus on the best indicator for performing these environmental evaluations. The purpose of this study is to examine the common performance indicators used to assess the environmental benefits of municipal waste systems to determine if there is agreement between them regarding which system performs best environmentally. Focus is placed on how indicator selection influences comparisons between municipal waste management programs and subsequent system rankings. The waste systems of ten municipalities in the state of New York, USA, were evaluated using each common performance indicator and Spearman correlations were calculated to see if there was a significant association between system rank orderings. Analyses showed that rank orders of waste systems differ substantially when different indicators are used. Therefore, comparative system assessments based on indicators should be considered carefully, especially those intended to gauge environmental quality. Insight was also gained into specific factors which may lead to one system achieving higher rankings than another. However, despite the insufficiencies of indicators for comparative quality assessments, they do provide important information for waste managers and they can assist in evaluating internal programmatic performance and progress. To enhance these types of assessments, a framework for scoring indicators based on criteria that evaluate their utility and value for system evaluations was developed. This framework was used to construct an improved model for waste system performance assessments.
The hyporheic zone is the subsurface area below and adjacent to a stream where groundwater mixes with stream water, through vertical, lateral, and longitudinal flows. The hyporheic zone connects the stream to uplands and other terrestrial environments. It is a zone of distinct faunal communities, high biological diversity and ecological complexity, and is the site of chemical processing and transformations of ground-and stream waters. The hyporheic zone is important to the overall ecosystem ecology of the stream, and it can influence stream water chemistry. Flows, reactions, and biota in the hyporheic zone are heterogeneous and patchy, making it difficult to clearly describe the ecotone in a straightforward, general way. Nitrogen processing, especially denitrification, appears to be widespread in the hyporheic zone. The hyporheic zone, as with most aquatic systems, is often impacted by human activities. Stream restorations rarely consider potential effects on the hyporheic zone, but careful project choices can enhance the condition of the hyporheic zone, and so increase uptake of nitrogen by stream-associated environments as partial mitigation of continuing and increasing releases of reactive nitrogen, potentially reaping short-term benefits to estuarine environments that might not be as quickly realized from source control measures.
A B S T R A C TMethane (CH4) is now considered a bridge fuel between present fossil (carbon) economy and desired renewables and this energy molecule is projected to play an important role in the global energy mix well beyond 2035. The atmospheric warming potential of CH4 is 28-36 times, when averaged over a 100-year period, that of carbon dioxide (CO2) and this necessitates a close scrutiny of global CH4 emissions inventory. As the second most abundant greenhouse gas (GHG), the annual global CH4 emissions were 645 million metric tons (MMT), accounting for 14.3% of the global anthropogenic GHG emissions. Of this, five key anthropogenic sources: agriculture, coal, landfills, oil and gas operations and wastewater together emitted 68% of all CH4 emissions. Landfills are ranked as the third highest anthropogenic CH4 emission source, behind agriculture and coal mines, and emissions from the waste sector are expected to reach almost 800 million metric tons CO2 equivalent (MMTCO2e) in 2015.The two largest economies spewed out 42% (14% (US) and 28% (China)) of the world's total greenhouse gas (GHG) emissions; these two countries are also the largest producers of municipal solid waste (MSW). The United States averages 250 MMT of MSW annually, of which about 63% enters landfills. In 2015, there were 2434 landfills in the United States and CH4 from these landfills accounted for 138 MMTCO2e released into the atmosphere and represents 17.7% of all US CH4 emissions. China had 580 landfills and treated 105 MMT of MSW in 2013. Methane produced from landfills contributes about 13% of total CH4 emissions in China. Almost 50% of landfills in China did not install efficient LFG collection and utilization systems to make them manageable so a great deal of CH4 and CO2 are emitted without intervention. Recent data show that globally, 45 billion cubic meters (bcm) of CH4 or 282 million barrels of oil equivalent (boe) was annually released from landfills into the atmosphere. Managing methane emission from landfills is a global challenge, though China lags behind in managed landfills that contribute to adverse health effects on the population. Moreover, the rich organic content of MSW in China indicates that CH4 emissions there may be underestimated. The China unmanaged landfill scenario is further duplicated in developing as well as in least-developed countries.This review starts with a dialog on CH4 emissions and climate change and the chemical changes the CH4 molecule undergoes in the atmosphere (Section 1). Section 2 deals with identification of global CH4 emissions from key sources, particularly anthropogenic, among those are agriculture, coal mines, landfills, oil and gas operations and wastewater. Although each of these sources is descriptive on their own, the focus of Section 3 is on landfills with particular emphasis on the United States and China, two largest producers of waste. The quantitative measurement of CH4 emissions is still uncertain so Section 4 is devoted to various CH4 estimation models, such as United States Environm...
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